Yong Yang Xiamen University
Christian Masquelier Université Picardie Jules Verne
YingShirley Meng University of California San Diego
Atsuo Yamada University of Tokyo
L2: Interfacial Phenomena and In-situ Techniques for Electrochemical Energy Storage and Conversion II
Tuesday PM, April 26, 2011
Room 2008 (Moscone West)
2:30 PM - **L2.1
Microstructures Evolution of Working Alloying Anodes of Li-ion Batteries Revealed by In-situ Transmission X-ray Microscopy.
Nae-Lih Wu 1 Show Abstract
1 Department of Chemical Engineering, National Taiwan University, Taipei Taiwan
Several metals that form alloys with Li are potential anode materials for achieving rechargeable Li-ion batteries of high energy density. However, they all suffer from dramatic microstructural deformation during electrochemical lithiation and de-lithiation, that leads to poor cycle life. Knowledge of the dynamics of such deformation processes is valuable to the development of practical alloying anodes. Previous in-situ techniques are limited to monitoring dimensional variations. In this work, the microstructures evolving within the interior of the Li-alloying anode particles during the electrochemical processes have been revealed with high resolution by transmission X-ray microscopy (TXM). Studies on Sn, SnO, SnSb and Si anode particles will be presented, in accompany with in-situ XRD data.
3:00 PM - **L2.2
In situ Electrochemical Depth-resolved XAFS Study on Interfacial Phenomena between Electrode and Electrolyte for All Solid-state Lithium-ion Battery.
Yoshiharu Uchimoto 1 , Toyoki Okumura 1 , Tomoya Uruga 2 , Hajime Tanida 3 , Koji Amezawa 4 , Yuki Orikasa 3 , Hajime Arai 3 , Zempachi Ogumi 3 Show Abstract
1 Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Kyoto, Japan, 2 , JASRI, Sayo-gun, Hyogo, Japan, 3 Office of Society-Academia Collaboration for Innovation, Kyoto University, Kyoto, Kyoto, Japan, 4 Graduate School of Environmental Studies, Tohoku University, Sendai , Miyagi, Japan
The improvement of the ionic transfer at the interface between solid electrolyte and electrode is crucial for the development of high power solid-state batteries. The possible factors for interfering the ionic transfer at the interface, for example the lattice mismatch, the distribution of the ion concentration with the formation of space-charge layer and the reacted heterogeneous phase etc, has been considered. The in-situ analytical technique to clarify these chemical and physical properties of solid/solid interface is extremely important. For this purpose, we have developed a novel depth-resolved X-ray absorption spectroscopy (XAS) to observe the chemical state and local structure of the internal area of all solid-state lithium-ion battery, which were obtained by the analysis of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), respectively. The LiCoO2 / Li2O-Al2O3-TiO2-P2O5-based glass ceramics (LATP glass, manufactured by OHARA Inc.) multilayer was used as model sample in this presentation. LiCoO2 and LATP glass are one of the candidates of cathode and electrolyte materials for all-solid state lithium- ion batteries, respectively.The LiCoO2 (100 nm) / LATP glass multilayer was prepared by pulsed laser deposition. LATP glass sheet was used as a substrate. XAS measurements of the samples were performed at the beam-line 37XU at SPring-8, JASRI, Japan.When the incident X-ray enters into the sample, the fluorescence X-ray is emitted. The signals detected at lower angles are only from the surface vicinity since the escape fluorescence X-ray is self-absorbed by the sample, while those at higher angles are from deeper area as well as the surface. A PILATUS detector containing a lot of pixel channels can detect 194 different angle signals at the same time, which makes depth resolved XAS possible. The detector with higher number detects the signal at the lower detected angle. The absorption peaks of Co K-edge shows the comparison of the intensity of the fluorescence X-ray on the Co K-edge absorption edges at different pixel channels. These results indicate the depth resolution is 2-3 nm. As the results of analyzing the difference of XANES and EXAFS Co K-edge spectra at each detector, the change of electronic and local structure around the interface compared with LiCoO2 bulk were obtained. In conclusion, we have developed a novel depth-resolved X-ray absorption spectroscopy (XAS) for the clarification of electrochemical property of all solid-state lithium- ion battery.
3:30 PM - L2.3
In Situ Characterization of Ni-Rare-earth-doped Ceria Anodes for Solid-oxide Fuel Cells Using an Environmental Transmission Electron Microscope.
Vaneet Sharma 1 , Peter Crozier 1 , Renu Sharma 2 1 , James Adams 1 Show Abstract
1 School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona, United States, 2 Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland, United States
Rare-earth doped CeO2 is a promising candidate material for intermediate-temperature
(500 °C to 700 °C) solid-oxide fuel-cell (IT-SOFC) anodes. Understanding the nanoscale phenomena and fundamental processes taking place in the anode material under near-reaction conditions is
necessary to enable optimization of the anode. Environmental transmission electron microscope (ETEM) is a powerful tool that allows us to study the dynamical changes in nanostructure and morphology of the
material under redox conditions at high temperature. In this research, interfacial interactions between Ni metal and Pr-doped ceria (PDC) in 0.1 mass fraction (10 wt%) Ni particles-loaded-PDC nanopowder of
composition Ce0.90Pr0.10O2 were studied in situ in the temperature range of 400 °C to 700 °C and under 100 Pa (≈1 Torr) of H2. A preliminary study done on pure
PDC under similar conditions showed a surface disordering phenomenon associated with the reduction of Ce4+ to Ce3+. The oxidation state of Ce was determined by electron energy-loss spectroscopy.
High resolution images acquired at 200 °C in the absence of H2 showed highly continuous lattice fringes in the nanoparticles indicating a high degree of crystallinity. After reduction at 650 °C in H2,
lattice fringes were mostly absent and a disordered structure was clearly seen. Ex situ reduction was performed on the same material at 900 °C in 0.05 volume fraction of H2 in He.
Subsequent examination in the TEM showed similar surface disordering, in agreement with the in situ results. High resolution images acquired during in situ reduction of Ni-PDC showed the formation of a
reduction zone with a similar disordered structure around the Ni/PDC interface at 420 °C. The existence of the Ce3+ state was confirmed by electron energy-loss spectra acquired under reducing conditions in the
vicinity of a Ni particle. The spatial extent of the reduction zone was approximately 10 nm from the metal/ceramic interface. Dissociation of molecular hydrogen to atomic hydrogen at the Ni surface and its subsequent
‘spillover’ at the Ni/PDC interface may be the mechanism for the reduction zone formation. The results from in situ characterization of Ni-(Gd,Pr)-doped ceria will also be presented and compared with Ni-PDC data.
Power density and open circuit voltage measurements in the temperature range 500 °C to 700 °C will be presented from model SOFCs fabricated from the same anode materials. Correlations between nanostructures observed under
in situ reducing conditions and anode performance will be discussed.
3:45 PM - L2.4
On-Chip, In-situ TEM Platforms for the Characterization of Battery Nanomaterials.
Arunkumar Subramanian 1 , John Sullivan 1 , Jianyu Huang 1 , Michael Shaw 1 , Nicholas Hudak 1 , Ganesan Nagasubramanian 1 Show Abstract
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States
We present two chip-based, in-situ transmission electron microscopy (TEM) platforms for characterizing the performance of individual nanomaterials used as electrodes in lithium-ion (Li-ion) batteries. Each platform is based on small micromachined silicon chips that serve three purposes: (1) enable isolation of individual electrode nanoparticles, (2) provide electrical contact to the particle(s), and (3) enable structural characterization inside a TEM during electrochemical polarization of the particle in a Li-ion compatible electrolyte. For particle placement and isolation, we employ dielectrophoretic (DEP) nanoassembly to assemble, or even co-assemble, anode and cathode nanoparticles, including SnO2, MnO2, Si, and LiFePO4 nanowires/particles. These are assembled on to patterned metal electrode pairs that are supported by thin electron-transparent silicon nitride membranes, thus enabling in-situ TEM of structural changes as well as characterization of the electrical conductivity of the particles. Two strategies are used for preparing the electrochemical cells containing liquid electrolytes for use inside the TEM. The first approach relies on an un-sealed single chip platform wherein we use vacuum-compatible ionic-liquids as the ion-conducting electrolytes. The second approach focuses on a two-chip approach where a sealed, ultra-thin (100nm depth) cavity is created to encapsulate conventional carbonate-based electrolytes within the electrochemical cells. In this talk, we will focus on the following aspects: (1) fabrication techniques and results for the single and two-chip platforms, (2) first experimental results from the in-situ TEM operation of the lithium cells based on all-nanowire / nanoparticle electrode constructs, including results from the lithiation of MnO2 and SnO2 nanowires. We anticipate this capability to be a powerful tool for identifying and optimizing electrode materials and coatings to improve battery performance in terms of energy density, rate capability, or cycle life. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE, Office of Basic Energy Sciences user facility. Portions of this work were also supported by a Sandia National Labs LDRD project and the NEES Energy Frontier Research Center, Award Number DESC0001160. Sandia is a multi-program laboratory operated by Sandia Corp., a wholly-owned subsidiary of Lockheed Martin Co., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
4:30 PM - **L2.5
Surface Modification of Cathode and Anode to Improve Life and Safety for Automotive Applications.
K. Amine 1 , I. Belharouak 1 , Z. Chen 1 , H. Wu 1 , Z. Zhang 1 , Y. Qin 1 , A. Abouimrane 1 Show Abstract
1 Chemical Sciences and Engineering Division, Argonne National Lab, Argonne, Illinois, United States
In its goal of developing more fuel efficient vehicles, the US Department of Energy in collaboration with the US auto industries are focusing on high-power and high energy lithium-ion batteries to meet the energy storage requirements for HEV and PHEV applications. Under these auspices, Argonne National Laboratory is investigating several different lithium ion chemistries in order to address the calendar life, cost and safety of high power and high energy lithium ion batteries for transportation applications. The surface reactivity between the charged electrode and electrolyte is mainly responsible for the limited calendar and cycle life of lithium batteries. Several surface modification of cathode using metal fluorides and oxides nano-coating at the particle level was carried out in order to suppress these reactivities at the interface that causes high impedance of the cell. Furthermore and in order to prevent reactivities between the charge anode and the electrolyte, several functional additives that polymerize or reduces at the surface of the carbon were used to form a very stable SEI layer leading to a very long cycle life even at high temperature. The characterization of these protective films will be discussed and their effect on the cell performance will be shown.
5:00 PM - L2.6
Use of In-situ TEM Characterization to Probe Electrochemical Processes in Li-ion Batteries.
Raymond Unocic 1 , Leslie Adamczyk 1 , Nancy Dudney 1 , Daan Hein Alsem 2 , Norman Salmon 2 , Karren More 1 Show Abstract
1 Materials Science and Technology, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 2 , Hummingbird Scientific, Lacey, Washington, United States
In electrical energy storage systems, interfaces play an active role in controlling the electrochemical energy conversion process. Of critical importance to the performance and life-cycle of lithium ion batteries is the formation of the solid electrolyte interphase (SEI), which is a passive interfacial, nm-scale film that forms at the electrode/electrolyte (solid/liquid) interface as a result of electrolyte decomposition reactions during electrochemical cycling. Due to the dynamically evolving nature of the SEI, it has proven difficult to design experiments that will reveal details regarding SEI formation mechanisms as well as how its structure and chemistry progress during electrochemical cycling. In-situ electron microscopy provides a viable means to investigate structure-property relationships of energy storage materials under electrochemical conditions such that changes can be studied in real-time and at high temporal and spatial resolution. A newly developed in-situ electrochemical cell TEM holder (Hummingbird Scientific) is being used to demonstrate the ability to investigate the formation of the SEI on the graphite anode during electrochemical cycling experiments within ethylene carbonate and propylene carbonate based organic liquid electrolytes. The unique feature of this device is the capability to wholly containing volatile and corrosive liquid electrolytes while placed into the high vacuum environment of the TEM. This enables the direct imaging of the electrode material, interfaces, and surfaces under electrochemical control through the electrolyte layer. The development and implementation of this unique tool will enable fundamental research related to electrical energy storage systems. Prospects for future in-situ TEM studies on energy storage materials will also be discussed.Research supported by (1) the Office of Vehicle Technologies, Office of Energy Efficiency and Renewable Energy (2) the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the Office of Basic Energy Sciences, U.S. Department of Energy, and (3) ORNL's Shared Research Equipment (SHaRE) User Facility, which is sponsored by the Office of Basic Energy Sciences, U.S. Department of Energy.
5:15 PM - L2.7
Investigation of Phase Transition Delay in LiFePO4/FePO4 upon Charge by Using Synchrotron Techniques.
Xiaojian Wang 1 3 , Cherno Jaye 2 , Bin Zhang 3 , Yongning Zhou 1 , Haiyan Chen 4 , Jianming Bai 5 , Hong Li 3 , Xuejie Huang 3 , Fischer Daniel 2 , Xiao-Qing Yang 1 Show Abstract
1 , Brookhaven National lab., Upton, New York, United States, 3 , Institute of Physics, Chinese Academy of Sciences, Beijing China, 2 , National Institute of Standards and Technology, Gaithersburg, Maryland, United States, 4 , New Jersey Institute of Technology, No, New Jersey, United States, 5 , Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Since the pioneer work of Goodenough’s group , olivine-structured LiFePO4 has been studied intensively as cathode material for lithium ion batteries due to its good safety characteristics and high thermal and chemical stabilities. In-situ XRD shows the lithiation/delithiation mechanism in LiFePO4 is a two-phase transition between LiFePO4 and LiFePO4. However, the details of how the new phase is nucleated and propagated are still being debated. The shrinking-core model was proposed first : during charge, the FePO4/LiFePO4 interface migrates from the surface to the core simultaneously in each particle, accompanied with the increase of lithium-deficient phase of and the decrease of Li-rich phase. It is reversible process for discharge. On the other hand, using electron microscopy, Chen et.,  and Laffont et al., reported their observation of the formation of FePO4 and LiFePO4 domains in platelet-like primary particles (platelet-type model). By X-ray diffraction and high resolution transmission electron microscopy, Delmas et al., observed the co-existence of fully intercalated and fully deintercalated individual particles at certain charged state, and proposed a domino-cascade model . Recent X-ray Photoelectron Spectroscopy results  also revealed a continuous evolution of the Fe3+/Fe2+ ratio at the surface of the particles upon charge, corresponding to the average content of electrochemical reaction. Due to the nature of surface sensitive (analysis depth around 5 nm) and surface only capability, XPS is a great tool to get the structural information at the surface, but unfortunately, not the bulk. In this study, synchrotron radiation techniques including in-situ X-ray diffraction (XRD), in-situ X-ray absorption spectroscopy (XAS) and ex-situ soft XAS provide a detailed picture of the whole extraction process. A delay, not only for crystal structure, but also electronic structure, can be observed: in-situ XRD experiment shows that the appearance of crystallized FePO4 is almost at x=0.35; In-situ XAS experiment also indicates that the electronic structure in Li1-xFePO4 delays to the electrochemical data. By further soft XAS analysis of Fe L-edge XAS data, we attribute the observed phase transition delay during lithium extraction to the slow Li ion diffusion in the bulk part of LiFePO4/FePO4 system. The work was supported by the U.S. Department of Energy, Office of Basic Energy Science, and the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, under the program of Vehicle Technology Program, under Contract Number DEAC02-98CH10886. Xiaojian Wang is supported by the Northeastern Center for Chemical Energy Storage, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract Number DE-SC0001294.
5:30 PM - L2.8
WITHDRAWN 4/26/11 Micro Focus X-ray CT: In-situ Measurement of Electrode Materials for Lithium-ion Batteries.
Jessica Weber 1 , Leonid Lev 1 Show Abstract
1 Global R&D and Planning, General Motors, Warren, Michigan, United States
Non-destruction evaluation (NDE) of lithium-ion batteries for electric vehicles is an essential tool for insuring quality during mass production as well as for examining new electrode/electrolyte system technology. In particular, micro-focus x-ray computed tomography (CT) is used to develop a three-dimensional image of the electrode materials of Li-ion batteries during the aging process. Battery capacity fade and an increase in impedance are two major concerns for the implementation of electric vehicles in the automotive industry. Over the cycle life of the Li-ion battery, capacity fade is associated with complex structural and chemical changes in the electrode material. Micro-focus x-ray CT has been used to evaluate the structural properties of electrode materials of Li-ion batteries in-situ during different cycle numbers and temperatures. Based on these x-ray CT analyses and other supportive NDE techniques (i.e. electrochemical impedance spectroscopy), we present a comprehensive understanding of the material degradation and aging mechanisms of Li-ion batteries.
5:45 PM - L2.9
In Situ Investigation of Electrode Structure under Different Operating Conditions Using Synchrotron High Energy X-ray.
Jian Xie 1 , Yang Ren 2 Show Abstract
1 Mechanical Enginering, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, United States, 2 , Argonne National Laboratory, Argonne, Illinois, United States
The increasing demand in safer and higher performance rechargeable batteries for broad applications has led to global efforts to develop advanced electrode materials, electrolyte components and additives, and other cell components. There is a critical need in understanding key material issues in batteries under realistic conditions and in real time. We will present a recent application of synchrotron high-energy x-ray diffraction (HEXRD) for in-situ nondestructive material characterization of commercial 18650 cells and the structural characterization of advanced battery materials. Our experimental work includes in-situ HEXRD studies of LiFePO4 cathode and MCMB anode materials under different operating conditions. New peaks have been observed for MCMB anode under overcharging condition which is associated with the graphite structural change. The Li plating was also investigated in situ using HEXRD under different conditions in combination with EPR study.IN addition, we will present the material structural change during solid-state synthesis, time-resolved measurements during hybrid pulse characteristic test (HPPC) of a full battery, and in-situ study of Si-Li interaction. Our results provide important interfacial property-structure-performance information for in-depth understanding of advanced energy materials and the safety and performance of batteries.
Yong Yang Xiamen University
Christian Masquelier Université Picardie Jules Verne
YingShirley Meng University of California San Diego
Atsuo Yamada University of Tokyo
L4: Interfacial Phenomena and In-situ Techniques for Electrochemical Energy Storage and Conversion IV
Wednesday AM, April 27, 2011
Room 2008 (Moscone West)
9:30 AM - **L4.1
Investigation on Electrochemical Stability of the SEI Film on Various Anode Materials for Li-ion Batteries.
Hong Li 1 , Xuejie Huang 1 , Liquan Chen 1 Show Abstract
1 Renewable Energy Laboratory, Institute of Physics, Chinese Academy of Sciences, Beijing China
Forming a solid electrolyte interphase (SEI) on the surface of anode in carbonate-based nonaqueous electrolyte in lithium ion batteries is nearly unavoidable due to the reduction of organic solvents and salts in relatively low potential below 1.2 V vs Li+/Li. The SEI layer is identified as a complicated mixture by many authors, especially D. Aurbach. The components in the SEI film are influenced by the type of electrolyte and electrode material, discharging rate and temperature. The SEI film is regarded as an electronic insulating but Li ion conducting phase. This can explain the termination of the formation reaction of the SEI film. Accordingly, the thickness of the SEI should be less than the electron tunneling length, typically, less than 2 nm. And the SEI film should be stable upon charging (delithiation) in certain voltage range. However, according to wide investigations, it has been found that the SEI film is electrochemically decomposable and the thickness can be as thick as 100 nm. The stability of the SEI film determines the columbic efficiency, internal resistance, cyclic performance and safety. In this report, the thickness, composition, electrochemical stability of the SEI on various anode materials, such as carbon, silicon and transitional metal oxide have been observed by several techniques, such as HRTEM, CV, FTIR, STM, TG-DSC-MS. Possible strategies to form stable SEI film, such as surface coating, forming core/shell structure with stable surface, tuning compositions of the electrolyte, are also introduced. Acknowledgement: This work was supported by NSFC (50730005), CAS (KJCX2-YW-W26)and “973” project (2007CB936501).
10:00 AM - L4.2
Synthesis and Electrochemistry of Monoclinic Li(MnxFe1-x)BO3: A Combined Experimental and Computational Study
Atsuo Yamada 1 , Nobuyuki Iwane 2 , Yu Harada 2 , Shin-ichi Nishimura 1 , Yukinori Koyama 3 , Isao Tanaka 3 Show Abstract
1 , The University of Tokyo, Tokyo Japan, 2 , Tokyo Institute of Technolog, Yokohama Japan, 3 , Kyoto University, Kyoto Japan
The lithium-ion battery is the most advanced energy storage system that has conquered the portable electronics market, but it has been considered unsuitable for large-scale applications such as plug-in hybrid vehicles due to cost, safety, and calendar life issues. Research in materials science is approaching a possible solution to these problems by the combination of abundant Fe as a redox center and covalent (PO4)3- oxyanion units with fixed oxygen, leading to the use of LiFePO4 with olivine-type structure as a cathode material. A high level of stability, safety, significant cost reduction, and huge power generation are now on the verge of being guaranteed. Replacing the (PO4)3- anion to smaller and lighter (BO3)3-, namely LiMBO3 (M = transition metal) compounds, could possibly increase the theoretical capacity by approximately >1.3 × however, such systems have not been thoroughly investigated to date. Here we present the successful solid state synthesis of a complete solid solution of Li(MnxFe1-x)BO3 with monoclinic structure and the optimization processes to maximize its performance as a lithium battery cathode. Details of the intrinsic electrode properties, including the degradation mode, are demonstrated, followed by systematic investigation of the reaction mechanisms by ex situ X-ray diffraction, Mössbauer spectroscopy, X-ray absorption spectroscopy, and ab initio calculations.
10:15 AM - L4.3
In Situ X-ray Absorption and Diffraction Studies of Ni and Fe Substituted Layer Structured Li2MnO3 Based Cathode Material during Electrochemical Cycling.
En-Yuan Hu 1 , Kaliyappan Karthikeyan 2 , Yun-Sung Lee 2 , Kyung-Wan Nam 1 , Xi-Qian Yu 1 , Xiao-Jian Wang 1 , Xiao-Qing Yang 1 Show Abstract
1 Chemistry, Brookhaven National Laboratory, Upton, New York, United States, 2 Applied Chemical Engineering, Chonnam National University, Gwangju Korea (the Republic of)
Li2MnO3-based material in the form of xLi2MnO3●(1-x)LiMO2 solid solution, (M can be Cr, Fe, Co and Ni) not only offers low cost, better thermal stability and safety advantages over conventional cathode materials, but also can reach a capacity which is almost double of that the most widely used cathode material LiCoO2 can deliver[1,2]. Therefore, this new material has received worldwide attention and is considered as one of the candidate cathode materials for the next generation of lithium-ion cells. However, this composite material suffers from problems of difficult preparation and poor cyclability. It was found that the derivative of this material, the iron and nickel doped Li2MnO3 based materials, such as Li1+x(Mn0.4Fe0.2Ni0.4)1-xO2, 0∠x∠0.5, can be made by a simple “mixed hydroxide method” with enhanced electrochemical performance. In order to study the Li insertion/extraction behaviors of this material during charge/discharge cycling, we applied synchrotron-based X-ray techniques, including in-situ X-ray diffraction (XRD) and in-situ X-ray absorption spectroscopy (XAS). The results are presented in this paper.AcknowledgementThe work at Brookhaven National Lab. was supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, under the Vehicle Technology Program, under Contract Number DEAC02-98CH10886. Xiaojian Wang is supported by the Northeastern Center for Chemical Energy Storage, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract Number DE-SC0001294. Thackeray, M. M.; Johnson, C. S. et al., J. Mater. Chem. 15 (2005) 2257. Thackeray, M. M.; Kang, S.H. et al., J. Mater. Chem. 17 (2007) 3112. Tabuchi M.; Nakashima, A. et al., J. Electrochem. Soc. 149 (2002) A509. Karthikeyan, K.; Jo, A. R. et al., 218th ECS meeting in USA, Las Vegas. Abstract number #1083.
10:30 AM - L4.4
Uncovering Li-ion Diffusion near Lithium-ion Battery Cathode Electrolytes Interface at the Nanoscale.
Senli Guo 1 , Thomas Arruda 1 2 , Stephen Jesse 1 2 , Nina Balke 1 , Sergiy Kalnaus 2 , Claus Daniel 2 , Sergei Kalinin 1 2 Show Abstract
1 CNMS, ORNL, Oak Ridge, Tennessee, United States, 2 MSTD, ORNL, Oak Ridge, Tennessee, United States
Lithium ion batteries have become a successful solution for consumer electronics and are promising for applications in hybrid and fully electric vehicles due to their high energy and power densities. Full utilization of their capabilities is however hindered by insufficient understanding of nanoscale processes associated with Li-ion diffusion during intercalation/de-intercalation, including the reversible ones that form part of normal battery operation, and irreversible ones that lead to the capacity feign or failure. While the importance of diffusion-strain coupling in Li-ion battery materials has been realized by the researchers and the AFM technique has been applied to study changes in the surface morphology of battery cathode and anode materials during the battery charging-discharging cycle, development of techniques allowing for mapping of Li-ion diffusion at the nanoscale is still scarce. The Electrochemical Strain Microscopy (ESM) method based on strain-bias coupling was recently developed and allows for studying Li-ion kinetics in battery materials at the nanometer scale, which is of fundamental importance for a better understanding of the irreversible processes. The preliminary results have shown the capability of mapping Li ion diffusion within active electrode material in the air, when the AFM tip changes the Li ion concentration in the small region underneath it by applying local periodic electric bias. In this work, we extend to probe the bias-induced Li-ions diffusion across cathode/electrolyte interface in liquid environments, including model aqueous solutions and Li-conductive electrolytes. In addition, the ESM measurements will be performed at different states of charge of the cathode material, revealing the influence of mechanical degradation on the ionic diffusion.This research at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725, was sponsored by the Vehicle Technologies Program for the Office of Energy Efficiency and Renewable Energy. Part of this research has been conducted at ORNL’s Center for Nanophase Materials Sciences sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. DOE. Dual-beam FIB and electron microscopy were performed at the Shared Research Equipment Collaborative Research Center at ORNL, sponsored by the Scientific User Facilities Division, Office of Basic Energy Science.
10:45 AM - L4.5
Understanding Surfaces and Interface Structures of Transition Metal Oxides.
Yoyo Hinuma 1 , Ying Meng 1 Show Abstract
1 Nanoengineering, University of California, San Diego, La Jolla, California, United States
Understanding the properties at the surface of a material or at the interface between materials provides insights to design and optimize better energy storage and conversion materials. The surface energy affects the shape of particles. LiCoO2 and LiFePO4 are two examples of anisotropic materials with energy applications, namely the active cathode material of Li ion batteries. Thus, knowledge of the surface energy and surface microstructure when the material is cleaved in different orientations is necessary to find methods to optimize processing conditions in these materials. Issues such as the surface-electrolyte interface and degradation of electrodes are interface phenomena that may become bottlenecks in electrode performance, and knowing the root cause of these bottlenecks is critical to improve electrochemical properties. Surface modeling using ab-initio calculations of thin slabs in vacuum is a powerful method to investigate the precise environment of surfaces. Physical properties such as change in lattice parameter or local electronic structure can be obtained from these calculations. However, the surface microstructure, including ordering and charge state of atoms, must be carefully monitored for precise modeling. Surfaces with various interfaces may be calculated as long as interfaces are designed appropriately, creating a powerful tool in understanding the surface in addition to experimental techniques.We will present how different surfaces and interfaces in transition metal oxides with energy applications, for example the spinel / layered structure interface in various orientations, affect the surface energy and relaxation of atoms near the interfaces. Ab-initio calculations based on Hubbard U correction to the generalized gradient approximation (GGA+U) to density functional theory (DFT) will be used.
11:30 AM - L4.6
Scanning Probe Microscope Measurements of Thermodynamically and Kinetically Controlled Transport in Solid Ionic Conductors.
Stephen Jesse 1 , Amit Kumar 1 , Leonard Donovan 1 , Albina Borisevich 1 , Sergei Kalinin 1 Show Abstract
1 , Oak Ridge National Laboratory, Oak Ridge , Tennessee, United States
Scanning probe microscopy opens a universal pathway for probing bias-induced phase transitions and electrochemical transformations in solids on the level of tens of nanometers and often single structural defect such as grain boundaries and isolated dislocations. In these, the SPM tip concentrates an electric field in a nanoscale volume defined by the size of the tip-surface junction, changes the phase state of the material induced by the locally applied field. The changes are determined through the electromechanical response, resonant frequency, or the quality factor of the cantilever. However, the intrinsic aspect of all first order phase transitions is that they are (a) hysteretic and (b) can have a strong kinetic component. Until now, most hysteresis studies, including those involving ferroelectric switching and electrochemical strain mapping, are currently done with little attention to relaxation kinetics. In this work, we demonstrate how the thermodynamically and kinetically controlled processes during ferroelectric switching and oxygen vacancy migration can be differentiated on the basis of relaxation of the signal during hysteresis measurement. Spatially-resolved mapping of the hysteresis loops with simultaneous relaxation measurements have been done using electrochemical strain microscopy (ESM), a scanning probe microscopy based technique that measures ionic transport via local strain. Measurements have been performed on ferroelectric materials including bismuth ferrite (BFO) films as well as ionic electrolyte materials yttrium stabilized zirconia (YSZ) and samarium doped ceria (SDC). Signal decay models have been applied to extract average relaxation coefficients and correlated maps of the relaxation parameters have been obtained. The relaxation studies reveal regions of enhanced activity with increased oxygen ion diffusivity. Thus, the relaxation studies associated with hysteresis can provide us with new insight into whether the process is controlled by thermodynamics or is dominated by kinetics. This research was sponsored by the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy. Part of this research was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Division of Scientific User Facilities, U.S. Department of Energy.
11:45 AM - L4.7
Nanoscale in Situ Characterization of Li-ion Battery Electrochemistry via Scanning Ion Conductance Microscopy.
Albert Lipson 1 , Mark Hersam 1 2 Show Abstract
1 Materials Science and Engineering, Northwestern University, Evanston , Illinois, United States, 2 Chemistry, Northwestern University, Evanston, Illinois, United States
To rationally guide future improvements in Li-ion battery technology, a nanoscale understanding of in situ electrochemical processes as a function of processing and cycling is highly desirable. Towards this end, we employ scanning ion conductance microscopy (SICM) to probe both the nanoscale topography and electrochemistry of Li-ion battery electrodes in the battery electrolyte. To date, SICM has been almost exclusively utilized to study biological systems in aqueous electrolyte, due to its ease of use in liquids and completely non-contact nature . In contrast, here we demonstrate the first use of SICM in non-aqueous electrolytes and in an inert atmosphere, which are requirements for studying Li-ion batteries in situ.In particular a borosilicate pipette pulled to approximately 100 nm outer diameter is filled with the battery electrolyte and a Tin wire is inserted into the pipette. The sample immersed in the electrolyte is lithiated or delithiated by an auxiliary lithium electrode. The pipette is oscillated vertically, which produces an AC current that depends on the tip-sample spacing due to physical occlusion of the pipette opening by the sample. During scanning, a feedback loop adjusts the vertical position of the pipette in an effort to keep this AC current constant, thus achieving nearly constant tip-sample spacing is achieved . The electrochemical current variation across the sample is then measured with ~100 nm spatial resolution by recording the DC current flow through the pipette.In this talk, we will report our initial in situ SICM measurements on Li-ion batteries. The observed nanoscale variations in electrochemical current will be discussed in the context of spatial inhomogeneities in the original electrode material and the evolving solid-electrolyte interface/interphase (SEI).References J. Gorelik, N. N. Ali, et al., Tissue Eng. 2006, 12, 657 A. I. Shevchuk, J. Gorelik, et al., Biophys. J. 2001, 81, 1759.
12:00 PM - L4.8
In Operando Investigation of SOFC Electrodes Using Synchrotron-based Ambient Pressure X-ray Photoelectron Spectroscopy (AP-XPS) in a Novel Two-environment Chamber.
Anthony McDaniel 1 , Farid El Gabaly 1 , William Chueh 1 , Kevin McCarty 1 , Michael Grass 3 , Zhi Liu 3 , Hendrik Bluhm 2 Show Abstract
1 , Sandia National Labs, Livermore, California, United States, 3 Advanced Light Source Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 2 Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Electrochemical technologies will be increasingly used to supply energy to the world withoutcontributing to climate change. These technologies can store and convert energy with unsurpassedefficiencies through, for example, the charging and discharging of batteries or the inter-conversion of electrical and chemical energy via fuel cell and electrolyzer. Perhaps the most important phenomena to understand in electrochemical energy storage/conversion is how electric charge is transferred across interfaces and subsequently stored in material phases and/or double layers. Specific questions include: 1) what chemical species transfer charge, 2) where is charge transferred in the heterogeneous system and 3) which reactions limit rates? Addressing these critical questions is challenging because of the physical complexity of these systems, which consist of a variety of electrified materials undergoing chemical reactions, as well as the difficulties associated with making meaningful in operando observations. For example, traditional diagnostics of electrochemistry, such as impedance spectroscopy, do not directly reveal the chemical information needed to resolve detailed kinetic pathways of surface electrochemistry.We have developed an approach that simultaneously characterizes chemical information and accurately measures the electrical potential landscape in systems with condensed-phase electrolytes. This is accomplished by using a new diagnostic based on synchrotron X-ray spectroscopies that we have been developing at the Advanced Light Source (ALS, LBNL, Berkeley, CA ). Photoelectrons are used as a contact-less probe for the direct measurement of the electric inner potential everywhere in a electrochemical cell operating at near ambient pressure. This information, in addition to space-resolved chemical characterization of the surface species showing changes induced by the application of an electric potential will be discussed. AP-XPS measurements reveal 1) the chemical identity of adsorbates, 2) the chemical state of the active materials and 3) how electric potential is distributed through the functioning materials. This important information is obtained simultaneously with traditional electrical characterization in gas environments of several torr, which is sufficient pressure to generate meaningful electrical current from the gas/surface reactions. We will describe a novel vacuum chamber design that uses a hermetically sealed membrane electrode assembly to fully isolate the gas environment of the anode from that of the cathode.
12:15 PM - L4.9
Nonlinear Coherent Laser Spectroscopy of In Situ SEI Growth.
Prabuddha Mukherjee 1 , Dana Dlott 1 Show Abstract
1 Chemistry, University of Illinmois at Urbana Champaign, Urbana, Illinois, United States
Solid Electrolyte Interphase (SEI) plays an important role in the charging and discharging mechanisms of Lithium Ion Batteries (LIB). In order to study SEI formation in situ, we use a nonlinear coherent infrared spectroscopic technique termed broadband multiplex vibrational sum-frequency generation (SFG) spectroscopy. SFG, being based on the 2nd order polarization, vanishes in (centrosymmetric) electrodes and electrolytes and is thus an interface-specific probe of SEI formation. Our spectroelectrochemical cell permits the acquisition of SFG spectrum during successive charge/discharge cycles and is adaptable to a variety of electrode and electrolyte materials. In our initial studies we used ethylene carbonate (EC) as the nonaqueous electrolyte, a Li cathode and a model anode that was a clean polycrystalline gold surface. We measured the SFG spectra of EC at the Au surface, under open circuit conditions and also during 6 consecutive cyclic voltammograms (CVs). We observed transitions of the SEI in the CH-stretch region and in the carbonyl stretch (~1800 cm-1) region. From our SFG measurements we observed that the SEI CO stretch transition evolved in shape and intensity with increasing number of charge/discharge cycles. This intensity reaches a constant value at the end of the 5th cycle, where the spectral characteristics were quite different from what was observed after the 1st cycle, and quite different from unreacted EC. Data using other materials commonly found in LIBs will, we hope, also be presented.This work was supported by the Center for Electrical Energy Storage - Tailored Interfaces, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-AC02-06CH11357 subcontract 9F-31921.
12:30 PM - L4.10
Thermal Stability Study of Surface Modified Ni-based Cathode Materials Using in situ- XRD, Hard and Soft X-ray Absorption Spectroscopy during Heating.
Kyung-Wan Nam 1 , Xiao-Jian Wang 1 , Xiqian Yu 1 , Enyuan Hu 1 , Sang-Hoon Kim 2 , Seong Min Bak 2 3 , Kyung-Yoon Chung 2 , Byung Won Cho 2 , Xiao-Qing Yang 1 Show Abstract
1 Chemistry Dept, Brookhaven National Lab, Upton, New York, United States, 2 Advanced Battery Center, Energy Division, Korea Institute of Science and Technology, Seoul Korea (the Republic of), 3 Department of Material Science & Engineering, Yonsei University, Seoul Korea (the Republic of)
The research and development of hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV) and electric vehicle (EV) are intensified due to the energy crisis and environmental concerns. Having the highest energy density among all rechargeable batteries, lithium-ion battery is considered as the best candidate among rechargeable batteries for transportation applications. In order to meet the challenging requirements of powering those vehicles, the safety characteristics of lithium-ion battery need to be thoroughly studied and significantly improved. For such studies, the thermal stability is the key issue, especially for using the Ni-based layered cathode materials, which have a merit of high capacity. It was reported that at highly delithiated (i.e., charged) states, the reduction of Ni4+ during heating releases oxygen that can accelerate severe thermal runaway by reacting with the electrolyte and leads to catastrophic failure of the battery. One effective way to improve the thermal stability of Ni-based cathode materials is the surface coating or modifications with thermally stable compounds (e.g., ZrO2, Al2O3, AlF3, etc). However, there is little information available about how the surface modification suppresses the thermal decomposition of charged cathode materials in detail. In this work, we have monitored the electronic and crystal structural changes of the charged nickel based cathode materials (e.g., Li1-xNi0.8Co0.15Al0.05O2 and Li1-xNi1/3Co1/3Mn1/3O2) with and without surface modifications (e.g., ZrO2 and Al2O3 coatings) using synchrotron based in situ- time-resolved X-ray diffraction (TR-XRD), hard and soft X-ray absorption spectroscopy (XAS) techniques during heating. Combination of TR-XRD, hard and soft XAS techniques allow us to distinguish the electronic and crystal structure differences between the bulk and surface of charged cathode materials during heating. The result will provide valuable information for the development of new cathode materials with better thermal stability and the improvement in thermal properties of the materials being used currently by surface modifications. TR-XRD spectra were recorded as a set of circles on a Mar 345-image plate detector in the transmission mode at beamline X7B at National Synchrotron Light Source (NSLS). Soft and hard XAS spectra were measured at beamline U7A and X19A&X18B at NSLS, respectively. ACKNOWLEDGMENTThe work done at Brookhaven National Lab. was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. DOE under Contract No. DE-AC02-98CH10886. The work done at KIST was supported by Global Research Lab. Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (MEST) [grant number: 2010-00351].
12:45 PM - L4.11
In Situ Investigation by Raman Spectroscopy ofProton Exchange Membranes During Fuel Cell Operation.
Anna Martinelli 1 , Nicolas Sergent 2 , Christina Iojoiu 2 Show Abstract
1 Chemical and Biological Engineering, Chalmers University of Technology, Göteborg Sweden, 2 LEPMI, INPG, Saint Martin d'Hères France
The development of polymer electrolytes alternative to the hydrated systems, where the proton transport is primarily assisted by water, is a hot subject in the field of low-temperature fuel cells. Considerable efforts are spent to develop electrolytes based on ionic liquids (ILs), i.e. molecular salts that melt at around room temperature. A straightforward way to exploit ILs in solid-like electrolytes is to swell perfluorinated polymeric membranes [1-3]. The physicochemical properties of these materials are conventionally studied ex situ or post mortem, whereas in situ investigations  are often technically much more complicated and therefore not so extensively performed. In this contribution we present the development of a fuel cell for in situ Raman measurements. In this cell, the two gas chambers are safely separated by a set of air tight gaskets, the in- and out-lets for the gases are exchangeable and an evacuation system for the water produced at the cathode is provided. A thin optical window allows the penetration of the laser light through the polymer electrolyte (between the meshes of the Pt grid electrodes) to record Raman spectra during operation. The electrolyte consists in a neutralized Nafion membrane swelled with a protic ionic liquid, whereas pure H2 and O2 are used at anode and cathode, respectively. Due to a favorable combination of optical properties (such as refractive index and transparency to visible), Nafion membranes can be investigated through the whole thickness (∼180 μm) without a significant loss in signal . This allows to characterize the electrolyte from anode to cathode (or vice versa) under operation, and thus to investigate the dissociation of charged species or the concentration gradients of the liquid phases through the membrane. Our results confirm a certain degree of water diffusion towards the anode, whereas a concentration gradient is observed for the ionic liquid accumulating at the cathode. This is in agreement with results from precedent studies of proton exchange membranes  and proofs the validity of the cell for in situ spectro-electrochemical investigations.References C. Iojoiu, M. Martinez, M. Hanna, Y. Molmeret, L. Cointeaux, J.-C. Leprêtre, N. El Kissi, J. Guindet, P. Judeinstein. Polym. Adv. Techn. 19, 1406-1414 (2008) A. Martinelli, A. Matic, P. Jacobsson, L. Börjesson, A. Fernicola, S. Panero, B. Scrosati, H. Ohno, J. Phys. Chem. B 111 (43), 12462-12467 (2007) A. Martinelli, A. Matic, P. Jacobsson, L. Börjesson, M.A. Navarra, S. Panero, B. Scrosati, J. Electroch. Soc. 154 (8), G183-G187 (2007) H. Matic, A. Lundblad, G. Lindbergh, P. Jacobsson, Electrochemical and Solid-State Letters, 8 (1) A5-A7 (2005) A. Martinelli, N. Sergent, T. Pagnier, Journal of Raman Spectroscopy 2010, in manuscript
L5: Interfacial Phenomena and In-situ Techniques for Electrochemical Energy Storage and Conversion V
Wednesday PM, April 27, 2011
Room 2008 (Moscone West)
2:30 PM - **L5.1
Graphite Structural Degradation in Li-ion Cell Anodes.
Robert Kostecki 1 , Frank McLarnon 1 , Laurence Hardwick 1 , Vijay Sethuraman 1 Show Abstract
1 EETD, LBNL, Berkeley, California, United States
Graphitic anodes exhibit surface structural damage during cycling in Li-ion cells [1,2,3], especially at high charging rates and elevated temperatures. Signatures of this damage appear in the Raman spectra of cycled graphitic anodes as increased intensities of the carbon D-band (~1330 cm-1) with respect to the G-band (~1580 cm-1). This surface damage alters the electrocatalytic properties of the graphite and thereby affects the SEI layer growth and composition, but it does not significantly change the electrochemical properties of graphitic anodes. However, the resulting continuous SEI layer reformation and electrolyte reduction contribute to Li-ion cell performance decline during cycling. In this study we investigate the mechanism of graphite surface structural damage and its effect on anode performance and life. A diagnostic evaluation of model surface-modified anodes is carried out, and implications for Li-ion cell degradation mechanisms are discussed.We found that anode surface disordering occurs primarily at potentials corresponding to low lithium concentrations in graphite (1.0↔0.18 V), compared to potentials at which stage 1&2 LixC compounds are present (0.15↔0.005 V) . Raman mapping of anodes cycled between these limits for 200 cycles at C/5 showed that the ID/IG ratio increased from 0.3 for a fresh electrode to 0.45 for deep cycling and 0.6 for shallow cycling. This result suggests that the initial phase of lithium intercalation into graphite (ca. Li0.05C6) is responsible for most of the damage to the graphite surface structure. The increase of the graphite d-spacing from 3.35 Å to 3.7 Å at the edges of graphene domains leads to a local stress build up, and ultimately C-C bond breakage across the graphene planes. This effect is likely to be intensified at higher cycling rates or elevated temperatures, where more-rapid charge transfer-kinetics result in a steeper lithium concentration gradient between the surface and bulk regions of the graphite particle.REFERENCES1. R. Kostecki and F. McLarnon, J. Power Sources, 119, 550 (2003)2. E. Markevich, G. Salitra, M. D. Levi, and D. Aurbach, J. Power Sources, 146, 146 (2005) 3. L. J. Hardwick, H. Buqa, M. Holzapfel, W. Scheifele, F. Krumeich, and P. Novák, Electrochim. Acta, 52, 4884 (2007)4. L. J. Hardwick, M. Marcinek, L. Beer, J. B. Kerr, and R. Kostecki, J. Electrochem. Soc., 155, A442, (2008)
3:00 PM - **L5.2
XANES and XPS Study on Positive Electrode Materials of Lithium-ion Battery.
Hironori Kobayashi 1 , Masahiro Shikano 1 , Hironobu Hori 1 , Hiroyuki Kageyama 1 , Yuuki Takenaka 2 , Yoshinori Arachi 2 , Kuniaki Tatsumi 1 Show Abstract
1 , AIST, Ikeda, Osaka Japan, 2 , Kansai Univ., Suita, Osaka Japan
Lithium-ion battery (LIB) is key technology on the application for Plug-in Hybrid Vehicle (PHEV) and Electric Vehicle (EV). Therefore there has been a lot of research on positive electrode materials, negative electrode materials, and electrolytes etc... Of these components, most attention was paid to the positive electrode materials in order to improve the battery performance of power output and energy density largely. Recently, we focused on the surface structure of the positive electrode materials and investigated the change in the surface structure during long cycles and initial Li de-intercalated process using both X-ray absorption near-edge structure (XANES) and X-ray photoemission spectroscopic (XPS) technique. The O K-edge XANES analysis, measured at the beamlines of BL27SU (SPring-8) and BL4B (UVSOR), is effective method to detect the NiO-like cubic phase and Li2CO3 and can obtain both information on the surface and bulk structures using the total electron yield (TEY) and fluorescence yield (FY) mode. XPS and high-resolution hard x-ray photoemission spectroscopic (HX-PES) studies are also effective method to detect Li2CO3, hydrocarbons, ROCO2Li, polycarbonate-type compounds and LiF on the surface of the positive electrode materials. In addition, HX-PES, measured at the beamline of BL47XU (SPring-8), can detect the depth-profile of the positive electrode materials without sputtering. In this paper, we will talk about two topics and show that the combination of XANES and XPS technique is a powerful method for investigating the surface structure at the positive electrode materials. One topic is to investigate positive electrode materials after cycle testing of high-power Li-ion battery cells and the relationship between power fade and the surface state of the positive electrode materials will be discussed. Second topic is to investigate Li de-intercalation mechanism in the Mn-rich layered oxides with high capacity and the relationship between capacity and the surface state of the positive electrode materials will be discussed. Finally, we are grateful to the New Energy and Industrial Technology Development Organization (NEDO) because part of this work was carried out in the “the Li-EAD project of NEDO in Japan.
3:30 PM - L5.3
Electrochemical Lithiation of Cubic Modification of Tin (α-Sn).
Alexander Kraytsberg 1 , Yair Ein-Eli 1 Show Abstract
1 Materials Engineering, Technion-Israel Institute of Technology, Haifa Israel
The behavior of cubic allotropic modification of tin (α-Sn) toward lithium electrochemical intercalation/de-intercalation is reported. The cycling stability of α-Sn electrode is superior as compared with cycling stability of tetragonal allotropic modification of tin (β-Sn). SEM study reveals that, unlike β-Sn, α-Sn crystal grains preserve the integrity in course of lithiation/de-lithiation cycles. Significant potentials shift in the charge/discharge stages in α-Sn electrode, with reference to β-Sn-electrode, is demonstrated. The potential shift is discussed in terms of different elastic energy changes in course of lithium intercalation process for β-Sn and α-Sn crystal grains.
3:45 PM - L5.4
Understanding the Electronic Properties of Electrode Materials by Photon in Photon out Spectroscopy.
Jonathan Lee 1 , Tony van Buuren 1 , Trevor Willey 1 , Jeff Dahn 2 Show Abstract
1 , LLNL, Livermore, California, United States, 2 , Dalhousie University, Halifax, Nova Scotia, Canada
In situ characterization of the evolution in electronic structure of electrode materials during repeated charge-discharge cycling is fundamentally important for more fully understanding the processes of charge storage and degradation, which, in turn, is essential for the development of new electrical energy storage (EES) materials with tailored properties and improved performance. X-ray spectroscopies provide ideal tools with which to obtain enhanced insight into the origins of electrode behavior in EES systems due to their capabilities for direct, element specific, characterization of the electronic densities of states. To date, in situ studies of EES materials have primarily focused on hard x-ray experiments due to the challenges associated with UHV compatibility and high photon attenuation of cells for soft x-ray measurements. Nonetheless, the use of soft x-ray spectroscopies to EES systems is vital since they provide complementary information that cannot be obtained via hard x-ray studies. We report the development of a cell for in situ soft x-ray emission spectroscopy and x-ray absorption spectroscopy studies of EES materials and will discuss experiments focused upon the x-ray spectroscopy characterization of a series of novel electrode materials for application in rechargeable Li-ion batteries. Prepared by LLNL under Contract DE-AC52-07NA27344.
4:30 PM - **L5.5
Combined First-principles and Experimental Study on the Polyanion Compound Cathode for Lithium Rechargeable Batteries.
K. Kang 1 Show Abstract
1 Department of Materials Science and Engineering and KAIST Institute for Eco-Energy and Nanocentury, KAIST, KAIST, Daejeon Korea (the Republic of)
The in-depth study of the multi-component effect on the structural and electrochemical properties of olivine cathodes is conducted using state-of-the-art first-principles calculations and experiments. The distribution of multiple transition metals in olivine structure alters local crystal structure and electronic structure, affecting its kinetic and thermodynamic properties. We find that local structure change, such as the reduced Jahn-Teller effect of Mn, significantly enhances both Li mobility and electron (polaron) conductivity when the redox Mn element neighbors Fe or Co. The unexpected one-phase Li insertion/extraction reaction of the multi-component olivine cathode is explained with respect to the multiple interactions of M/Li or M/Vacancy (M=transition metals). The redox potential of each transition metal also could shift as a result of charge redistribution and the relative energy change from the multiple M/Li interactions. Implications of multi-component olivine as a useful strategy for tailoring the electrochemical properties of olivine compounds are discussed for designing better-performing Li rechargeable batteries.
5:00 PM - L5.6
Interfacial Properties and Confinement Effects of Alkali Halide Brines in Carbon Nanopores.
Matthew Wander 1 , Kevin Shuford 1 Show Abstract
1 Chemistry, Drexel University, Philadelphia, Pennsylvania, United States
We are studying the properties of aqueous alkali halide brines in contact with charged and uncharged porous carbon electrodes using classical molecular dynamics simulations. These simulations provide an atomic scale description of capacitance and transport within different environments. Simulations were performed at zero electric potential and with atomic charges on the carbon consistent with the expected charging of experimental systems at 1V. Porous carbon electrodes are modelled as slit pores or nanotubes. Electrolytes were selected from within two atomic groups of elements, the alkali metals and the halides, allowing us to look at size specific trends. Overall, these systems show promise as high-capacity, high-power electrical energy storage devices. We observe enhancement of ion motion in the direction of the pore but very slow movement in the perpendicular directions. Ion diffusion decreases rapidly with decreasing poor size. In all but the smallest pores, the ions are fully hydrated. We observe increased ion pairing for the smallest pore sizes and at the higher concentrations. There is strong evidence of differential capacitance at all size scales, concentrations, and ion types, indicating that a certain amount of energy storage is contained within the organization of the ions over the entire voltage range.
5:15 PM - L5.7
Porous Sn-based Electrode/electrolyte Systems for Li-ion Batteries.
Lynn Trahey 1 , John Vaughey 1 , Michael Slater 1 , Michael Thackeray 1 Show Abstract
1 Chemical Sciences and Engineering Division, Argonne National Lab, Argonne , Illinois, United States
The first generation of Li-ion batteries for electric vehicles will be similar to those used in consumer electronics in that they will rely on graphitic carbon anodes paired with lithium metal oxide cathodes in an organic carbonate based electrolyte. Significant reductions in the battery volume, an important variable in transportation systems, can be made if the graphitic carbon electrodes are replaced by high volumetric capacity tin-based materials. A considerable obstacle to this replacement is the crystallographic volume expansion upon tin lithiation (to ~Li4Sn) that causes particle breakage resulting in short battery cycle life. This study is aimed at understanding and overcoming the shortfalls of tin anodes. We initially investigate the conformal deposition of tin onto highly porous copper current collectors, with the rationale that three-dimensional space for tin expansion will reduce particle loss. Establishing the optimum thickness of tin on copper, a compromise between capacity and cycle life, is sought and will be determined based on electrochemical cycling versus lithium using a 1.2 M LiPF6 in 3:7 wt. % ethylene carbonate / ethyl methyl carbonate electrolyte. Since tin anodes offer entirely different chemical interphases compared to graphite, new electrolyte systems and surface stabilization layers will be evaluated in order to establish a suitable electrode/electrolyte pair. Characterization tools include AC impedance spectroscopy, electrochemical cycling, and electrochemical quartz crystal microbalance used for gaining insight into the mass gain and viscoelastic properties of the solid electrolyte interphase (SEI) on tin. The irreversible capacity loss due to Li-ion trapping upon SEI formation is a large concern due to the high surface area of the proposed porous tin anodes, and can hopefully be addressed by creating the proper electrode/electrolyte interface.
Yong Yang Xiamen University
Christian Masquelier Université Picardie Jules Verne
YingShirley Meng University of California San Diego
Atsuo Yamada University of Tokyo
L7: Interfacial Phenomena and In-situ Techniques for Electrochemical Energy Storage and Conversion VII
Thursday PM, April 28, 2011
Room 2008 (Moscone West)
2:30 PM - **L7.1
In Situ Observation of the Electrochemical Lithiation of a Single SnO2 Nanowire Electrode.
Jianyu Huang 1 , Li Zhong 2 , Chong Min Wang 3 , John Sullivan 1 , Wu Xu 3 , Li Qiang Zhang 2 , Scott Mao 2 , Nicholas Hudak 1 , Xiao Hua Liu 1 , Arunkumar Subramanian 1 , Hong You Fan 1 , Liang Qi 4 , Akihiro Kushima 4 , Ju Li 4 Show Abstract
1 Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 3 , Pacific Northwest National Laboratory, Richland, Washington, United States, 4 Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
We report the creation of a nanoscale electrochemical device inside a transmission electron microscope – consisting of a single SnO2 nanowire anode, an ionic liquid electrolyte and a bulk LiCoO2 cathode – and the in-situ observation of the lithiation of the SnO2 nanowire during electrochemical charging. Upon charging, a reaction front propagated progressively along the nanowire, causing the nanowire to swell, elongate, and spiral. The reaction front is a “Medusa zone” containing a high density of mobile dislocations, which are continuously nucleated and absorbed at the moving front. This dislocation cloud indicates large in-plane misfit stresses and is a structural precursor to electrochemically-driven solid-state amorphization. Because lithiation-induced volume expansion, plasticity and pulverization of electrode materials are the major mechanical effects that plague the performance and lifetime of high capacity anodes in lithium-ion batteries, our observations provide important mechanistic insight for the design of advanced batteries. (Science, accepted)
3:00 PM - **L7.2
Factors Affecting Cyclic Durability of All-solid-state Lithium Polymer Batteries Using Poly(ethylene oxide)-based Solid Polymer Electrolytes.
Masanobu Nakayama 1 Show Abstract
1 Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya Japan
Electrochemical properties and performances of all-solid-state Lithium polymer batteries using standard PEO-based solid polymer electrolytes are reported and discussed. The assembled cell showed stable charge-discharge cycles (> 150 cycles) at 30 deg.C, due to desirable solid electrolyte interface (SEI) film formation at the SPE | cathode interface. However, sudden capacity fading for prolonged electrochemical cycles was indicated by accelerated aging test at higher current density (1 C) and temperature conditions (60 deg.C). Two sequential factors affecting the capacity fading are proposed through the studies of in situ 19F-NMR imaging, real-time monitoring of the total cell thickness, and electrochemical measurements such as AC impedance. One factor is degradation of the cathode sheet or cathode composite assembly, owing to cyclic volumetric change. The second factor is Li salt decomposition resulted in the electrolysis at cathode | electrolyte interface due to enhanced local polarization.
3:30 PM - L7.3
Electrochemical and Interfacial Studies of High Voltage Spinel and Mixed Oxide Positive Electrodes for Li-ion Batteries.
Surendra Martha 1 , Jagjit Nanda 1 , Wallace Porter 1 , Nancy Dudney 1 Show Abstract
1 Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
High energy positive electrodes are critical for increasing the overall energy density of Li-ion batteries . Recent developments have focused on high capacity cathodes by using Lithia rich compounds and 5V spinel (LiMn1.5Ni0.5O4) compositions [2-3]. For practical applications these batteries needs to be cycled around 5 V, which is close to the electrochemical stability window of most commonly used electrolytes (LiPF6 in EC-DMC). Further, there can be additional decomposition or degradation on the surface of the active materials that can be detrimental to their long term cycle life. In this work we shall compare the electrochemical stability (rate capabilities, cycleability) of the high capacity and high voltage positive electrodes in two and three electrode coin cell configurations using the standard LiPF6 in EC-DMC electrolytes and additives. This shall be followed by ex-situ characterization of the electrode surfaces maintained at different state of charge (SoC) using micro-Raman and X-ray Diffraction. Additionally, thermal stability of these materials (at different SoCs) would be analyzed using Differential Scanning Calorimetry in presence of electrolytes. AcknowledgementThis work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy.References1.S. K. Martha, J. Grinblat, O. Haik, E. Zinigrad, T. Drezen, J. H. Miners, I. Exnar, A. Kay, B. Markovsky, and D. Aurbach, Angew. Chem. Int. Ed., 2009, 48, 8559 –8563.2.S.-H. Kang, V. G. Pol, I. Belharouak, and M. M. Thackeray, J. Electrochem. Soc., 2010, 157, A267-A271.3. J. Liu, B. Reeja-Jayan and A. Manthiram, J. Phys. Chem. C, 2010, 114, 9528–9533.
3:45 PM - L7.4
The Effect of Film Thickness on Water Uptake and Interfacial Hydration in Ultrathin Polyelectrolyte Membranes.
Steven DeCaluwe 1 , Joseph Dura 1 , Andrew Baker 2 1 , Pavan Bhargava 3 1 , Charles Majkrzak 1 Show Abstract
1 , NIST Center for Neutron Research, Gaithersburg, Maryland, United States, 2 , University of Delaware, Newark, Delaware, United States, 3 , University of Maryland, College Park, Maryland, United States
One key challenge currently delaying the commercialization of Polymer Electrolyte Membrane Fuel Cells (PEMFCs) as a cost-effective and reliable technology for a range of applications is the management of membrane hydration across a variety of working conditions. While much effort has focused on the bulk structure, hydration, and transport properties of Nafion membranes, these properties likely have little relevance to the behavior of Nafion in the three-phase boundary regions of membrane-electrode assemblies (MEAs) in operating PEMFCs. Within the catalyst layers of MEAs, the electrolyte interfaces with several key materials, such as metal catalysts, carbon supports, and gaseous reactants. Not only do such interfaces significantly impact the polyelectrolyte properties in dimensionally confined catalyst layers, but they are also the site of key fuel cell losses and degradation mechanisms [1-3]. Characterizing and controlling the behavior of Nafion in these interfacial regions is thus necessary for efficient, reliable PEMFC operation.Here, we use Neutron Reflectometry (NR) to study hydration in Nafion films with varying thickness. NR is inherently sensitive to water structures in Nafion, and the thin-film geometry approximates the morphology of Nafion in PEMFC MEAs. Previous results from our group have identified multi-lamellar structures at the interface with SiO2 surfaces . The lamellae hydration level oscillates between water-rich and water-free, but the amplitude decays away from the support interface, converging to a bulk-like Nafion layer. This presentation will discuss the total water uptake and changes in lamellae for film thicknesses ranging from 6 to 220 nm, at 30 °C with a relative humidity of 90%. Results show three different regions of behavior as a function of film thickness. For films below 10 nm, the film consists entirely of lamellae. For film thicknesses between 10 and 50 nm, an outer bulk-like layer forms more than 10 nm from the SiO2 interface with a water volume fraction of approximately 15%. For thicknesses above 50 nm, the bulk layer water content increases to approximately 25%. While the thickness and hydration of the lamellae are fairly constant with increasing film thickness below 50 nm, the water content of the lamellar region increases sharply for films thicker than 50 nm. The implications of these results for fuel cell technology will be discussed, both in terms of fabrication and control strategies, and for the accurate simulation of Nafion in operating PEMFC MEAs, where the behavior of the polyelectrolyte is strongly influenced by interfacial phenomena.1. Siroma, Z. et al. Journal of Power Sources 189, (2009).2. Meng, H. & Wang, C. Y. J. Electrochem. Soc. 152, (2005).3. Sethuraman, V. A., Weidner, J. W., Haug, A. T., Pemberton, M. & Protsailo, L. V. Electrochim Acta 54, (2009).4. Dura, J. A., Murthi, V. S., Hartman, M., Satija, S. K. & Majkrzak, C. F. Macromolecules 42, (2009).
4:30 PM - L7.5
In Situ Look at Soluble Polysulphide Species in Lithium Sulphur Batteries.
Rezan Demir Cakan 1 3 , Robert Dominko 2 3 , Michel Armand 1 3 , Mathieu Morcrette 1 3 , Jean-Marie Tarascon 1 3 Show Abstract
1 , LRCS, University of Picardie Jules Verne , Amiens France, 3 , ALISTORE-ERI, Amiens France, 2 , National Institute of Chemistry, Ljubljana Slovenia
Sustainability has become an unavoidable issue in all major planning and undertakings for the future use of energy. In the field of rechargeable batteries, lithium-sulphur (Li-S) attracted main interest not only its low cost and environmentally benign but also higher energy density requirements. Although Li-S batteries posses high theoretical specific energy (2600 Wh/kg or 2800 Wh/l), the practical use encounter serious problems i) poor cyclability owing to the insulating nature of sulphur itself as well as its polysulphide species and complete reaction solid product (Li2S) ii) low active material utilization due to the soluble polysulphides which form as an intermediate during the battery operation. Generally, low intrinsic conductivity can be overcome by maintaining active material in an intimate contact with an electron conductive matrix. However, the main problem of the soluble polysulphides formation in the electrolyte still remains and has yet to be effectively solved in spite of the numerous attempts aiming to modify electrolyte formulation via additives or using polymer rather than liquid-type electrolytes. To fully combat such an issue, we must develop a fundamental understanding on the nature of the polysulfide species, formed as a function of sulphur reduction state in various electrolytes, in order to find better solvents, additives or salts. To conduct such a study we embarked in an in situ monitoring of the polysulphide formation by cyclic voltammetry measurements. This measurement is based on using modified 4-electrode Swagelok cell as an in situ analytical tool. Besides the standard Swagelok configuration, the 4-electrode cell has two additional perpendicular electrodes (wires) placed between the two separators. Soluble polysulphides in the electrolyte are reduced on the nickel wire and the cumulative charge of cathodic peak in the potential range between 2.25 V and 1.5 V versus platinum is used for the quantitative analysis. In a perfect agreement with the literature, the soluble species are generated at the high voltage plateau (2.4-2.3 V vs. Li) whereas less soluble species are formed at the lower plateau (2.0 V vs. Li). We conduct a survey of different electrolyte systems as well as different electrode architecture considering many parameters (temperature, time, etc.) in order to highlight the best configuration for the next generation Li-S batteries. As a whole, we show that this in situ analytical cell can be a powerful tool to enable faster and more reliable determination of the impact of additives, solvents, electrolyte salts and different composite architectures on the electrochemical behaviour of lithium sulphur battery for consequently long term operation.
4:45 PM - L7.6
In-situ Structural Characterizations of Electrocatalysis in Li Air Battery Using X-rays.
Naba Karan 1 , Mahalingam Balasubramanian 1 , Yang Ren 1 , Lynn Trahey 2 , Michael Thackeray 2 Show Abstract
1 X ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States, 2 Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois, United States
Li-air batteries, which have a significantly higher theoretical energy density than current Li-ion batteries, are being touted as the next generation of electrochemical energy storage systems. It is now an almost general consensus that successful Li-air battery action requires active electrocatalyst components, especially during charge. To this effect several groups are involved in discovering the most promising electrocatalyst for rechargeable Li-air battery action. At present, the reduction/oxidation reaction pathway at the air electrode including the role of the catalyst is poorly understood. Understanding the local structural changes around the active sites in an electrocatalyst during working battery conditions is crucial for understanding the reaction mechanisms involved, which is expected to pave the way for synthesis of newer electrocatalysts with superior properties. In order to gain useful information on the local structural evolution in electrocatalysts during Li-air battery working conditions we have employed x-ray absorption spectroscopic (XAS) experiments. XAS is an ideal method for the study of electrochemical systems, due to the penetrating ability of hard x-rays, which allows in-situ characterization in a suitably designed cell or reactor. An important advantage of XAS is the element specific nature of the technique, which permits investigation of the local structure of a particular constituent element in a composite catalyst sample to help understand the intermediates involved in the course of the air electrode reaction during electrochemical cycling of a Li-air battery. Our initial electrochemical studies showed that acid treated Li2MnO3 is a promising electrocatalyst with relatively low voltage hysteresis (between charge and discharge) for a Li-air battery. We have performed in-situ XAS experiments on Li-air battery with acid treated Li2MnO3 electrocatalysts using a specially designed electrochemical system suitable for simultaneous electrochemical and XAS measurements. The preliminary XAS data obtained is encouraging. A detailed analysis of the observed local structural evolution of the parent “electrocatalyst” in relation to the possible intermediates during the electrochemistry will be presented.
5:00 PM - L7.7
In Situ Study of Degradation Phenomena of SOFC Model Cathodes (LSM/LSCrM) on Yttria Stabilized Zirconia (YSZ).
Juergen Janek 1 , Anne-Katrin Huber 1 , Mareike Falk 1 , Marcus Rohnke 1 , Bjoern Luerssen 1 Show Abstract
1 Institute of Physical Chemistry, Justus-Liebig-University, Giessen Germany
Perovskite-type (La,Sr)MnO3 and YSZ are widely used as cathode and electrolyte materials in SOFCs (solid oxide fuel cells), and may be considered as a model-type electrode. Despite of intensive studies there still exist a number of open questions. These include morphological changes such as degradation or delamination and a change of the local composition (e.g. decomposition, segregation) and/or redox state under electrochemical polarization, and thereby, a variation of the electrochemical behaviour of the cell (e.g. activation under cathodic polarization, long-term stability). We studied the surface changes of operating LSM/YSZ electrodes in situ under various oxygen pumping conditions at approximately 500 °C and different oxygen partial pressures by XPS (x-ray photoelectron spectroscopy), SIMS (secondary ion mass spectrometry) and HREM (high resolution scanning electron microscopy). Electrochemical characterization in parallel was performed in order to correlate both electrical properties and spectroscopic results. In all three cases we designed electrochemical cells such that the spectroscopic/microscopic techniques can be directly applied. And we designed a geometrical well defined cathode model system via PLD (pulsed laser deposition) which was morphologically characterized by HREM and structurally via XRD. In situ SIMS and locally resolved XPS and SPEM measurements during heat treatment under UHV conditions show the decomposition of the LSM/YSZ electrode even without polarization. Manganese and strontium diffuse onto the YSZ surface and accumulate at the LSM surface and at the three phase boundary between electrolyte, electrode and gas phase. By applying an electrical potential, either cathodic or anodic, immediately diffusion processes take place. Under cathodic polarization strontium diffuses onto the electrolyte whereas manganese diffuses into the bulk of the LSM electrode. After applying an anodic potential a reversible diffusion of strontium and manganese appears.Morphological changes which appear under electrochemical polarization were studied with ex and in situ HREM measurements. Under anodic polarization formation of bubbles and the delamination of the surface could be examined and thereby a variation of the three phase boundary.
5:15 PM - L7.8
Layered Sodium Transition Metal Oxide Cathodes for Advanced Rechargeable Sodium-based Batteries.
Michael Slater 1 , Donghan Kim 1 , Sun-Ho Kang 1 , Shawn Rood 1 , Christopher Johnson 1 Show Abstract
1 Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois, United States
Ambient-temperature sodium batteries represent an attractive alternative to lithium-based battery chemistry due to the ubiquity of sodium and its associated lower cost. However, to enable this chemistry one must discover and develop new cathodes that have high performance and stability. We have recently synthesized new cathode materials for advanced sodium batteries based on layered sodium transition metal oxides. As electrodes, these materials operate by a single phase Na insertion-extraction process accompanied by negligible crystallographic volume change during cycling as determined by state-of-charge dependent powder diffraction experiments. Elemental analysis data indicate that approximately half of the sodium is removed from the parent structure upon charging, resulting in a specific capacity of ~ 100 mAh/g. While the plating problems of the Na metal in the non-aqueous electrolyte create coulombic inefficiencies during charge and limitations in long-term cycling, it was found that the discharge capacity for the cathode is highly reversible and stable. The electrochemical reaction mechanism of sodium intercalation was investigated using spectroscopic and electrochemical characterization tools. These new materials are an exciting step towards the development of practical sodium-ion batteries.
5:30 PM - L7.9
Three-dimensional Molecular Ion Transport in Ordered Polyelectrolyte Membranes.
Christy Landes 1 Show Abstract
1 Department of Chemistry, Rice University, Houston, Texas, United States
The ability to sequester and transfer charge and matter via functionally responsive materials requires a detailed understanding of mechanisms driving transport within these materials. Functional polymers possessing specific chemistry and morphology play a key role in the future charge storage applications. One challenge is an incomplete description of transport, especially within charged and crowded interfacial regions. Here, we use single-molecule fluorescence spectroscopy to reveal 3-dimensional details of mechanisms underpinning ion transport in an ordered polyelectrolyte polymer-brush. Resolving fluorescence emission over three discrete polarization angles allows reporting the extent to which these materials impart 3-dimensional orientation to charged guest molecules diffusing in the film. We report a global orientation parameter for the films, track coherent dipole angle progressions over time, and identify a unique transport mechanism: translational diffusion under restricted orientation.