The development of improved electrochemical energy storage devices depends critically on a detailed understanding of the physical and electrochemical processes at the electrode-electrolyte solid-liquid interface. Recent advances in in situ liquid cell electron microscopy, with its unique ability to provide simultaneous temporally and spatially resolved information as well as electrochemical parameters, enable exploration of the underlying physics of electrochemical reactions at the solid-liquid interface. Here we apply liquid cell electron microscopy to investigate the effect of additives on the morphology of electrochemical deposits. We have examined the deposition of zinc, an attractive anode material for low cost, recyclable batteries. Morphological control of zinc during deposition is required to avoid the formation of dendrites which may short the battery during charging. The inclusion of additives such as Bi in the electrolyte is known to modify the morphology and growth kinetics of Zn. Here, we use a liquid cell with three electrodes and the capability of liquid flow so that we can introduce acidic electrolytes of varying composition. We observe the deposition of Zn under galvanostatic conditions in electrolytes with different concentrations of the Bi additive, as well as changes in the Zn morphology when the additive is first supplied. We will compare these flow cell results to static liquid cell experiments (in a custom built liquid cell, the nanoaquarium) in which we have recorded Zn morphology during galvanostatic deposition, and we will discuss the benefits and pitfalls of flow capabilities in in situ electron microscopy for the study of processes during battery operation.

Cryo-Transmission electron microscopy is regarded as a powerful tool for the investigation of samples in a solution-like state. Due to the rapid freezing of the samples the sample is trapped in a thin ice layer and can be imaged under mild imaging conditions. However, dynamical processes are also trapped in this frozen state and cannot be analyzed easily. There is a growing demand for the in-situ investigation of such events and recently the utilization of specially constructed liquid cells for the investigation of solutions and dynamic processes are frequently use. Because of the expenses as well as because of the rather thick boundaries of such liquid cells, which require the utilization of scanning transmission electron microscopy techniques, we introduce here a simple and straightforward technique for the in-situ observation of nano-objects in liquid environments. Ionic liquids are molten salt-like compounds which virtually have no vapor pressure and remain liquid over a wide range of temperatures. These ionic liquids are known as excellent solvents for many materials and are used in synthesis as well as alternative solvents for nanoparticles, cellulose derivatives, nanoparticles, etc.. They have been also used to study self-organization processes of block copolymers.
Due to the negligible vapor pressure ionic liquids are also compatible with the ultrahigh vacuum requirements of TEM and can be prepared as a free-standing liquid support film in which the visualization of particles or suspended nanostructures can be achieved. This approach permits the study of particle movement, crystal formation in ionic liquids, or the growth of nanoparticles. Additionally, it will be demonstrated that ionic liquids provide useful intrinsic staining properties, which enable the visualization of e.g. core-shell polymer nanostructures, etc. This approach is able to close an important gap in the characterization of nanoparticles and small structures in the solution as it provides the possibility to study individual nano-objects in the solution-like state with high lateral resolution.[1]
[1] U. Mansfeld, S. Hoeppener, U.S. Schubert, Adv. Mater. 2013, 25, 761-765.

Since the inception of the concept of nanobattery with a single nanowire, tremendous progress has been made over the last few years on the direct in-situ TEM observation of structural and chemical evolution of materials related to energy storage. This is especially true for the case of anode materials for lithium ion battery. These in-situ TEM work have helped us to gain some insights on dynamic structural and chemical evolution of electrode materials that cannot be captured before. However, the design of the in-situ cell in the previous work, especially, the operating parameter of the cell during the in-situ testing is still far deviated from a real battery operating condition. Much effort is needed on designing of new cells that enable in-situ TEM study of battery under more realistic conditions. In this presentation, we will review, in retrospective and perspective, the overall progress of in-situ TEM study of battery materials, especially focusing on the challenges that related to anode, cathode, and solid electrolyte interface (SEI) for lithium ions battery and beyond, such as sodium ions and magnesium ions as well.

Battery cycle-life and safety depend critically on the morphological evolution of the electrode-electrolyte interface during charging and discharging. The potentially catastrophic formation of dendrites is one morphological evolution to be avoided. Recent advances in in situ liquid cell electron microscopy allow us to image the evolution of electrochemical deposition and stripping in real time with nanoscale resolution while controlling the current or potential during the process. The information acquired this way permits us to study process physics as a function of process conditions and electrolyte composition to obtain insights into the mechanisms leading to dendrite formation with the aim of devising means to avoid the same. Here we show in situ electron microscopy videos and electrochemical measurements obtained in a test system, the deposition and stripping of copper in an acidified copper sulphate solution. The experiments were carried out using our custom made liquid cell, the nanoaquarium, which is equipped with micropatterned platinum electrodes. These integrated electrodes were connected to a potentiostat to control and record the current and potential as functions of time during galvanostatic deposition. Simultaneously, the interface morphology evolution was imaged at video rate (30 images per second) as a function of current density using a Hitachi H9000 transmission electron microscope operated at 300kV. Correlating the imaging and electrical measurements facilitates synchronization between the morphology and the electrical data. We will describe the interface morphology and growth kinetics as functions of current density and time. We will show how this data can be used to measure the critical current at the transition from uniform growth to dendritic growth, and we characterize the onset of instability in the growth front. We will finally discuss the results within the context of battery cycling.

An understanding of the materials transformation and interfaces in electrochemical processes is critically important for identifying the failure mechanism or improving the lifetime of batteries and other relevant devices. In-situ transmission electron microscopy, which allows for real-time imaging of electrochemical processes in realistic liquid electrolyte environments with high spatial and temporal resolution, has attracted significant attention. Here, we report using an environmental biasing liquid cell operated in a transmission electron microscope to study electrochemical deposition and dissolution of metal dendrites and structural phase transformation during charge cycles in situ. A commercial electrolyte for lithium ion batteries (ethylene carbonate, dimethyl carbonate and LiPF6) was used. Phase transition of gold nanowires due to lithium ion insertion, solid electrolyte interface (SEI) layer formation, deposition and dissolution of lithium dendrites have been observed in real time. The current-voltage curve was recorded simultaneously during the charge cycles. Based on the combined in situ and ex situ studies we discuss novel mechanisms of transformation during charge cycles.
Electron Microscopy (NCEM) of the Lawrence Berkeley National Laboratory, which is supported by the U.S. Department of Energy (DOE) under Contract No. DE-AC02-05CH11231. HZ thanks the funding support from U.S. DOE Office of Science Early Career Research Program.

Although lithiation has been investigated extensively by theoretical simulation over a wide range of different electrode materials, there is a lack of experimental evidence and fundamental understanding on the initiation and evolution of lithiation atomically, which hinders our understanding of the fundamental operation mechanisms in a lithium ion battery. In this talk, using in-situ high resolution TEM, we report that the atomic scale lithiation process of a single SnO2 nanowire anode immersed in an ionic liquid electrolyte. We discovered unexpectedly a multiple-stripe and multiple-reaction-front lithiation mechanism that differs completely from the expected core shell lithiation mechanism. More specifically, the lithiation initiated multiple stripes with width of a few nanometers parallel to the (020) plane traversing the entire wires, serving as multiple reaction fronts for later stages of lithiation. Inside the stripes, we identified a high density of dislocations and enlarged inter-planar spacing caused by lithiation.

When crystalline particles are dispersed in their matrix, such as a solution or vapor, it is readily observed that particles larger than those of average size grow, accompanying the dissolution of smaller particles into the matrix at the same time. This particle coarsening process has generally been referred to as Ostwald ripening. As the physical properties of crystals significantly vary with their ultimate size and shape, observation and appropriate control of their growth and dissolution behavior during the ripening process have been recognized as important issues in crystallization studies over the past several decades. Recent advances in transmission electron microscopy (TEM) enable atomic-scale imaging in Li intercalation compounds for direct visualization of lattice defects, phase transition, and structural evolution (S.-Y. Chung et al., Angew. Chem. Int. Ed.48, 543 (2009); S.-Y. Chung et al., Adv. Mater.23, 1398 (2011)). In particular, a variety of techniques have been utilized for real-time observations in TEM, providing unexpected and new experimental findings (S.-Y. Chung et al., Nature Phys.5, 68 (2009); S.-Y. Chung et al., Nano Lett.12, 3068 (2012)). Using in situ high-resolution electron microscopy (HREM) with a heating specimen holder, in this study we demonstrate, for the first time, the atomic-level evaporation behavior of LiFePO4 crystals in real time at high temperature (S.-Y. Chung et al., J. Am. Chem. Soc. (in press)). Prior to detailed observation of crystal evaporation, we also investigated the growth behavior of atomically flat low-index surfaces. A systematic comparison with image simulations along with density-functional theory calculations demonstrated that the cations evaporate preferentially over the [PO₄]^3- oxyanions, accompanying fast charge transfer from the nearest-neighboring Fe and O. The present study thus shows that our combined technique based on high-temperature HREM and systematic image simulations is a powerful tool to understand the dynamic characteristics of crystal growth and evaporation.

Observation of electrochemical phenomena at nano-scale in an all-solid-state lithium ion battery is important for understanding of the role of interfaces. High resolution transmission electron microscopy (TEM) coupled with electron energy loss spectroscopy (EELS) is ideal to track lithium ion movement with high spatial resolution. Functional thin film battery prepared by sputtering has been sliced by focused ion beams and mounted on commercial grids to produce nano-batteries. First to establish consistent electrical biasing of nano-batteries, an in-situ FIB biasing method was accomplished followed by ex-situ TEM/EELS investigation. After successful in-situ FIB biasing, samples with suitable thickness are biased in-situ in TEM. We will present lithium ion tracking by EELS in the nano-scale batteries ex situ and in situ and correlate with their electrochemical profiles.

Li ion based energy storage devices with high energy density and long-term stability are considered as one of the most suitable candidates applied for consumer electronics and electric vehicles (EV). Nanostructured materials, especially nanowires, have attracted great interests due to a range of advantages in many energy related fields, such as short Li-ion insertion/extraction distance, facile strain relaxation upon electrochemical cycling, enhanced electron transport, and very large surface to volume ratio. Although the electrochemical properties could be improved, the fast capacity fading is still one of the key issues and the intrinsic reasons need be further understood.
To find out the reasons of fast capacity fading, the process was usually studied ex-situ after disassembling the devices. In-situ probing has been increasingly employed in nanotechnology, such as in-situ XRD, NMR or TEM. Here, we reported the single nanowire electrode devices designed as a unique platform for in situ probing the intrinsic reason for electrode capacity fading in Li ion based energy storage devices. In this device, a single vanadium oxide nanowire or single Si/a-Si core/shell nanowire was used as working electrode, and electrical transport of the single nanowire was recorded in situ to detect the evolution of the nanowire during charging and discharging. Along with lithium ion intercalation by shallow discharge, the vanadium oxide nanowire conductance was decreased over 2 orders. The conductance change can be restored to previous scale upon lithium ion deintercalation with shallow charge. However, when the nanowire was deeply discharged, the conductance dropped over 5 orders, indicating that permanent structure change happens when too many lithium ions were intercalated into the vanadium oxide layered structures. Different from vanadium oxide, the conductance of a single Si/a-Si core/shell nanowire monotonously decreased along with the electrochemical test, which agrees with Raman mapping of single Si/a-Si nanowire at different charge/discharge states, indicating permanent structure change after lithium ion insertion and extraction.
We demonstrate that during the electrochemical reaction conductivity of the nanowire electrode decreased, which limits the cycle life of the devices. The intrinsic reason for electrode capacity fading in Li-ion based energy storage devices was concluded, which may push the fundamental limits of the nanowire materials for energy storage applications.

The need for new materials with improved ion transfer properties continues to be one of the main pressing concerns in energy storage materials research. In accompanying this search for optimal materials, appropriate characterization tools to assess key parameters of newly developed materials are required.
This paper will focus on coupling electrochemical impedance spectroscopy (EIS) with fast gravimetric methods (fast quartz crystal microbalance (QCM)) under dynamic regime. This coupling, so called ac-electrogravimetry measures the usual electrochemical impedance, ΔE/ΔI (omega;), and the mass/potential transfer function, Δm/ΔE (omega;), simultaneously.[1-3] The main interests of this coupling are its ability to indicate the contribution of the charged and uncharged species and to separate the anionic, cationic, and free solvent contributions during the electrochemical/chemical processes. These features make the ac-electrogravimetry as an attractive and appropriate tool to investigate transfer/transport phenomena of charged and uncharged species in ion insertion materials.
As a pertinent example, the adaptation of ac-electrogravimetry to evaluate the ion (Li+, Na+hellip;) transfer phenomena in MnO2 based thin films will be discussed. As a functional metal oxide, MnO2 is one of the most attractive inorganic materials because of its physical and (electro)chemical properties, particularly in energy storage.[4] Thin films of MnO2 with Li+ ion intercalated are synthesized by a one-step electrodeposition method and the electrodeposition process is monitored by QCM.[5,6] The resulting LixMnO2 thin films are studied by classical (micro)structural characterization methods. The ion transfer properties (Li+ and Na+ in aqueous and acetonitrile solutions) are investigated by electrochemical quartz crystal microbalance (EQCM) and ac-electrogravimetry. Our primary findings based on the mass/potential transfer function, (Δm/ΔE (omega;)) report that the cations are inserted under their hydrated form and the free solvent molecules participate indirectly in the charge compensation process with different kinetic constants.
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[4]. L. Athoueuml;l, F. Moser, R. Dugas, O. Crosnier, D. Bélanger, T. Brousse, J. Phys. Chem. C 112 (2008) 7270.
[5]. M. Nakayama, T. Kanaya, J.W. Lee, B.N. Popov, Journal of Power Sources 179 (2008) 361.
[6]. N. Cherchour, C.Deslouis, B. Messaoudi, A. Pailleret, Electrochimica Acta 56 (2011) 9746.

Activated carbons with well developed surface area and porosity are very interesting materials especially for electrochemical capacitor (EC) applications. Because of the fact that EC charging/discharging process has strictly electrostatic character, electrochemical double layer capacitors are able to be charged and discharged even in a few seconds. Additionally, to achieve good performance and satisfy high power demands it is necessary to exploit materials characterized with great conductivity and very often with tailored porosity which is responsible for preserving excellent charge propagation. However, the capacitance values reported for these electrodes do not exceed 150-180 F/g. Higher capacitance values can be provided from additional faradaic reactions. Unfortunately, their high price completely eliminates them from commercial using.
Very interesting way to increase capacitance is to use electrode materials (activated carbons) which are electrochemically grafted by using different electrolytes. It means that electrolyte can generate particular functional groups on the surface of carbon electrode which are able to reversible redox reactions. It is a great advantage over pseudocapacitance received directly from the pseudocapacitive electrode material (e.g. transition metal oxides, conducting polymers) where the most limiting factors are slow diffusion and penetration of electrolyte. Electrochemical grafting is also much easier and quicker methods than chemical generation of electroactive groups on the electrode material&’s surface (e.g. during synthesis of electrode material), because this process proceeds in the same assembled system as further electrochemical investigation of its performance.
Three electrode cell investigation revealed changes in behaviour of positive and negative electrode when compared with performance of pure sulphuric acid. The origin of positive electrode capacitance changes from typical electrical double layer to faradaic one after grafting process which is in a great accordance with data obtained from cyclic voltammetry and galvanostatic charging/discharging technique. Apart from electrochemical investigation other techniques were used to confirm if the additional pseudocapacitance really comes from already grafted functional groups on the carbom electrode or directly from redox active electrolyte. For that purpose thermogravimmetric analysis conjugated with mass spectrometer was used and gave very promising results. Investigated electrode after grafting process revealed much higher weight loss than ungrafted one because of significant CO gas evacuation which might be related to decomposition of carbonyl groups. Additionally, Raman spectroscopy was used in order to follow the change in the material functional structure and the results will be discussed.

It is widely believed that hydrogen is an ideal clean and efficient carrier for storage and transport of energy. In this context storage of hydrogen is one of the key challenges in developing hydrogen economy. One of the most attractive ways for hydrogen storage is using magnesium hydride. Magnesium can absorb hydrogen in atomic form and thereby act as hydrogen "sponges". It gives not only an important safety advantage over the gas and liquid but also high hydrogen uptake (7.6 wt %). Hence, magnesium hydride is a safe, volume-efficient method for hydrogen storage. However, the slow reaction kinetics and high thermodynamic stability hinder practical applications of this material. To enhance the kinetics and modify the thermodynamics of hydrogenation, it is essential to study the hydrogenation process on the atomic scale by using transmission electron microscopy (TEM). In this study, we investigated the hydrogenation of magnesium films decorated with palladium particles at room temperature by using environmental TEM. In addition, the vacuum transfer specimen holder was also used in order to minimize the formation of oxide during sample loading. Samples were exposed to hydrogen at the pressure up to 10 mbar in the ETEM. During the hydrogen exposure, we observed of the formation of magnesium hydride successfully. In electron diffraction mode, the formation of two different hydride phases (β-MgH2 and γ-MgH2) was observed. We believe that this experimental observation leads to the fundamental understanding of the reaction mechanism of a hydrogen gas with magnesium.

Oxide materials are known to be active in a variety of redox reactions, making them important for many energy technologies. Unfortunately, the complex interactions between such reactions and the structural/chemical evolution of the oxide surface are not well understood. This has hindered progress in many areas, including solid oxide fuel cells, corrosion, and the development of new heterogeneous catalysts. However, with the advent of high precision growth techniques, epitaxial oxide heterostructures can now be synthesized with controlled strain, orientation, and surface termination, thereby allowing model studies of surface behavior. We examine the reactivity of epitaxial SrCoO3-δ thin films using in situ X-ray studies at the synchrotron, focusing on the kinetics of oxidation and reduction in these materials. Both the dynamics of surface reactions and phase transitions are studied, using both incoherent scattering techniques and x-ray photon correlation spectroscopy. We find that oxidation can be characterized by two distinct time constants, and different mechanisms for the spread of oxygen in this material will be discussed.

Few methods exist for examining SOFC surfaces under conditions that approach the operating conditions of a SOFC. A JEOL environmental scanning microscope with a hot stage permits imaging of samples under vacuum at temperatures up to 1000C. Because of thermal emission, images free of charging artifacts are obtainable on insulating and conducting surfaces without application of conducting coatings. Ni/YSZ anodes exposed to fuel mixtures with low levels of phosphine (PH3) often exhibit new phases on the surface. Previous work suggests that the new phases are nickel phosphides. To confirm this hypothesis, a Ni/YSZ surface with visible micron-size particles was examined at temperatures of 500C to 1000C. The particles melted between 900C and 1000C, while the Ni/YSZ structure exhibited no visible change. This result is consistent with the known lower melting temperatures of nickel phosphides relative to nickel.

Many important material systems in catalysis work at atmospheric or higher gas pressure environments but yet these catalysts are characterized in vacuum in a conventional transmission electron microscope (TEM) or at sub-atmospheric pressures in an environmental TEM. The use of hermetically sealed environmental cells (constructed within the specimen holder) can overcome this pressure gap by containing the gas between electron transparent silicon nitride windows etched in silicon microchips while the gas environment is changed via a gas inlet connected to the outside of the microscope. This in-situ characterization technique is crucially needed to provide mechanistic insights to the structural and chemical changes that occur in real world catalytic reactions.
However, the relationship between the differential pressure of the system and the operating pressure at the sample is not necessarily straightforward. Experimental parameters, such as the spacing between the SiN windows, can affect the resulting flow of gas near the sample. Furthermore, the thin SiN windows are subject to mechanical bowing, such that the spacing between windows varies both spatially across a window and with pressure. Chemical reactions in gaseous environment are influenced by the flow rate of the gas, which depends on both the channel size and the pressure.
Here we present in-situ TEM observations in atmospheric pressure gas at elevated temperatures and high resolution images of different catalytic materials at a range of pressures, where we have used Electron Energy Loss Spectroscopy (EELS) to more accurately determine the pressure in a gas flow stage at the sample. This is done by assessing the electron inelastic mean free path through the gas flow stage for a range of input gas flow rates. The results of this work will enable a greater understanding in morphological changes in catalytic materials as reactions are occurring, which in turn can lead to development of more efficient catalytic materials.

In spite of tremendous progress in recent years in nanowire gas sensorics, very little research has been done on the fundamental understanding of the interplay between surface reactivity and electronic transport in working nanowires devices under realistic operation conditions. Another rarely addressed issue is the electron transport and chemical sensing performance of the nanowire, which is affected by local electroactive inhomogeneities and potential barriers in nanowire such as near surface depletion regions and Schottky contacts. This work is aimed to address the above deficiency via in situ imaging electroactive inhomogeneities and electron transport inside the nanowire as a function of gas environment and temperatures.
In a course of this work, a single nanowire gas sensor was fabricated inside the membrane based-environmental cell equipped with a heater. The nanowire&’s strong temperature dependent conductivity was used as a thermometer of the entire device assembly. It was demonstrated that often the asymmetric Schottky barrier is formed at the nanowire&’s contacts what dominated the transport characteristics of the conducting channel. The nanowire responses to gas (2-propanol) with and without electron beam were analyzed quantitatively via conductometric measurements. The effect of electron beam irradiation as chemical activation mechanism of nanowire sensor has been discussed. EBIC technique was used for the first time to characterize the nanowire sensor during its operation in ambient pressure environment. The modulations of the EBIC resistive contrast were observed as a result of exposure to the analyte. The contrast forming mechanisms were qualitatively addressed in this work.

Micropatterned CdTe-CdS islands have been prepared through SiO₂ windows to enhance photovoltaic performance by relieving lattice mismatch stress. To efficiently measure their local response down to the nanoscale, a new measurement scheme is presented for mapping PV performance. The specimens are illuminated from below through an inverted optical microscope, during simultaneous scanning from above with a conductive atomic force microscopy (cAFM). Sequences of images are then acquired for a single area, each with incremented DC applied biases. The local I-V response for any given pixel position is then easily determined based on the cAFM contrast (current) at the corresponding location in each distinct image (voltage). Crucially, this provides drift-free photoconduction maps based on the resulting array of I/V spectra, here ranging from 0 to 240 picoSiemens (pS), with spatial resolution of ~5 nm based on 65,536 pixels that would take orders of magnitude longer to acquire using conventional cAFM based methods. The PV performance of continuous and microstructured films will be compared, and related to orientations within the polycrystalline cell based on EBSD results. For the CdTe-CdS films, enhanced photoconductivity is clearly observed for certain grains, and grain boundaries are clearly resolved, confirming the importance of microstructural control and grain boundary conductivity on polycrystalline PV performance.

Here we show that lithiation and delithiation of the electrode materials in lithium-ion batteries can induce significant variations in their properties, including their thermal conductivity and elastic modulus. The varying thermal conductivity electrode mateirals during lithiation and de-lithiation may be important to better understand thermal events in electrochemical energy storage systems, and in addition, may provide new opportunities for active control of thermal conductivity. We present in-situ thermal and elastic measurements of LiCoO2 as a function of lithiation via a time-domain thermoreflectance (TDTR) technique using an electrochemical cell consisting of a Li foil anode, a liquid electrolyte, and a thin film LiCoO2 cathode constructed in such a way to enable direct real time measurement of thermal and elastic properties during electrochemical cycling. The LiCoO2 thin film is deposited by RF sputtering and annealed at 500°C in air. The thermal conductivity of the LiCoO2 is determined by the best fit between calculation and the measured TDTR data. Along with thermal conductivity, the elastic modulus is evaluated by monitoring acoustic signals. We conclude the thermal conductivity decreases from ~6.4 to 4.6 W m-1 K-1 and elastic modulus decreases from 325 to 225 GPa as the cathode is delithiated from Li1.0CoO2 to Li0.6CoO2. Moreover, the thermal conductivity and elastic modulus change is reversible. The dependence of the thermal conductivity on lithiation appears to be related to crystalline phase transformations.

High voltage Ta capacitors have broad applications for energy storage in electric systems, where there are very strict requirements for stability and reliability. In situ stress measurements were employed to provide new insight into failure mechanisms in these materials. In particular, field induced crystallization of the capacitor dielectric at high voltages was investigated in detail. This work demonstrates that different mechanisms produce both tensile and compressive stresses during the operation of these materials. The magnitude of these stresses is large enough to substantially impact observed failure processes. Stresses are generated in the amorphous tantalum oxide (ATO)/Ta system during operation by hydration process, electrophoresis, further oxidization and crystallization. These stresses have been evaluated by in situ stress measurement on a thin film model system. Futhermore, the details and direct evidences of failure process of ATO under high electric field have also been investigated in this report. Stress results are paired with data from techniques including focused ion beam (FIB) lift-out, electron scanning microscopy (SEM), transmission electron microscopy (TEM), selected area diffraction (SAD), Energy-dispersive X-ray spectroscopy (EDS) and high resolution transmission electron microscopy (HRTEM) to explore the details and to provide direct evidence for the failure mechanism. Based on this series of results, the failure mechanism has been reassessed. This will guide the new approaches for improving the stability and reliability of Ta capacitor in future and open a door to study the failure mechanism of other capacitors.
1 School of Engineering, Brown University, Providence, RI 02912, USA.
2 Medtronic Energy and Components Center, 6800 Shingle Creek Parkway, Brooklyn Center, MN 55430, USA.
a suxin81@gmail.com, b mark.viste@medtronic.com, c joachim.hossick-schott@medtronic.com, e brian_sheldon@brown.edu.
* Corresponding author, B.W. Sheldon.

Interfacial reactions on electrical energy storage (EES) materials mediate their stability, durability, and cycleablity. Understanding these reactions in situ is difficult since they occur at the liquid-solid or solid-solid interface of optically absorbing materials that hinder the use of traditional spectroscopic techniques. Furthermore, since some interfaces involve liquids classic vacuum-based analytical methods can only probe reaction products that are stable under vacuum. NR is a neutron scattering technique highly sensitive to morphological and compositional changes occurring across surfaces and interfaces, including buried interfaces. It can be used to study such changes over lengths scales extending 1 nm to hundreds-of-nanometers. Neutrons, by virtue of their nature, are deeply penetrating and therefore ideally suited as a probe to study materials in complicated environments, such as electrochemical cells. Unlike x-rays, neutrons interact with the nuclear potential of constituent elements and are sensitive to light elements like Li and H. Neutrons are also sensitive to isotopic differences allowing for selective contrast variation in the design of experiments. For instance, 6Li and 7Li look very different to neutrons and this difference can be exploited in studying the exchange of Li during cycling to study the diffusion of Li through the solid electrolyte interphase (SEI) layer. We will present results of in situ NR studies of the high voltage thin film cathode material LiMn1.5Ni0.5O4 and a thin film anode material Li4Ti5O12 against a 1.2 molar LiPF6 in 1:1 ethylene carbonate - dimethyl carbonate electrolyte solution.

Safety is a critical issue for rechargeable battery technology. Due to the structure variation and complexity of battery systems, thermal properties of battery components are largely unknown. Here we perform in-situ thermal transport measurement on a micro-fabricated lithium ion battery. We observe highly reversible thermal behaviors of electrode materials during the charging/discharging cycles. The thermal conductivity of electrodes can be regulated by controlling lithium concentration and shows a significant contrast at different phases. This real time observation represents structure evolution during lithiation and delithiation process. The experimental results will help design safer batteries.
This material is partially based upon work supported as part of the “Solid State Solar-Thermal Energy Conversion Center (S3TEC)," 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-SC0001299/DE-FG02-09ER46577.

Capacitors store energy in the form of an electric field. At small scales, the use of 3D structures increasing the effective surface of the capacitor is a potential route for the development of high capacitance components [1]. In addition, there is an interest for low temperature processes to avoid thermal stress damages in more complex structures and to reduce the energy consumption of the fabrication process [2], which is profitable from the economical and environmental point of view.
In this context, electrochemical processes are a potential route for the fabrication of 3D capacitors because anodic porous silicon formation can be used to shape the 3D structure and a dielectric layer can be grown by anodic oxidation of silicon. However, the electrical properties of silicon oxide obtained by anodic oxidation are inferior to those of thermal oxide [2]. To produce anodic silica layers of higher quality, it is first necessary to better understand and control the growth of anodic silica. In this work, we report on the electrochemical formation of anodic silicon oxide, the in-situ characterization of the growing film by different techniques, and the comprehension of the growth mechanism.
The growth of anodic silica films is intimately linked to electrochemical oscillations related to the periodic variation of the electrical or morphological properties of the film [3]. To understand the link between the growth, the silica properties and the oscillations, we monitored the silica film during its electrochemical growth by combined in-situ Optical Stress Sensing (MOSS) and Spectroscopic Ellipsometry (SE), as well as by in-situ Inductive Coupled Plasma Spectrometry (ICP-OES). The high temporal resolutions (0.3 sec for the MOSS and 2 sec for the SE) allow the very precise monitoring of the change of internal stress and morphology of the silica film during the anodic polarization of silicon. ICP provides in-situ information about the film dissolution rate in hydrofluoric acid solutions.
It appears that, depending on the growth regime and the associated oscillatory behavior, some of the thin film properties are either constant or variable with time. From the mechanical point of view, the internal stress is about -325 MPa in the constant regime and varies between -100 MPa and -300 MPa during the growth in the variable regime. We determined the relation between the two growth regimes in order to advance the understanding and control of 3D porous anodic silica formation.
[1] M Nongaillard, F Lallemand, B Allard, Design for manufacturing of 3D capacitors (2010) Microelectronics Journal 41:845-85
[2] K Ohnishi, I Akira, Y Takahashi, S Miyazaki, Growth and characterization of anodic oxidized films in pure water (2002) Jpn J Appl Phys 41:1235-1240
[3] K Schönleber, K Krischer, High-Amplitude versus Low-amplitude current oscillations during the anodic oxidation of p-type silicon in fluoride electrolyte (2012) Chem.Phys.Chem. 13:2989-2996

Understanding lithiation process of Si at nanoscale becomes of prime importance to develop next generation Li-ion batteries since the nanostructured Si such as Si nanowires and porous nanostrcutrues were reported to enhance charging rate and avoid mechanical degradation due to the dramatic volume expansion of Si during lithiation. However, affirmative description of Li kinetics in nanostructured Si anode is still very limited. In the present work, we demonstrated in-situ lithiation of diverse Si nanostructures. First, our in-situ lithiation test showed unprecedentedly fast lithiation of a pristine Si nanowire. The measured diffusivity is even faster than any other in-situ lithiation test of Si and matching with the theoretically calculated diffusivity values. The mechanical properties of lithiated Si nanowires were also investigated using in-situ tensile testing, which provides a guidance of new nanostructure design of Si anode. Subsequently, we introduced a new design of nanostructured Si anode on a Polyimide (PI) substrate for future applications of flexible energy storage devices. Unlike other technique to fabricate nanostructure Si anodes, amorphous-Si was deposited directly on the polymer substrate having nano-hair like surface structure. In-situ lithiation tests found that this unique nanostructured Si anode hinders the delamination of an anode component resulting in higher capacity and longer life cycle than that of a-Si on the non- PI substrate or on a typical Cu foil substrate. We also characterized the lihitation behavior of carbon-fiber encapsulated Si nanoparticles which enhance mechanical reliability of Si based anodes during cyclic lithiation.

Lithium-ion batteries are critically important for a wide range of applications, from portable electronics to electric vehicles. However, the high-capacity electrodes in Li-ion batteries, such as Si and Ge, suffer from electrochemically-induced mechanical degradation that causes capacity fading. Drastic improvement of Li-ion batteries is hinged on the fundamental understanding of the physical mechanisms underlying lithiation/delithiation processes. We have developed methods for in-situ electrochemistry within a transmission electron microscope (TEM) to investigate phase transformation and morphological evolution in real-time during battery cycling. This presentation will focus on our recent progress using in-situ high-resolution TEM (HRTEM) to study the lithiation of Si electrodes (Liu et al, Nature Nanotechnology, 7, 749-756, 2012), which cannot be achieved using conventional battery testing techniques. Novel mechanistic information can be revealed by HRTEM, such as how lithium ions react with the crystalline electrodes to cause solid-state amorphization, and how dislocations form and evolve. A comparison was made for Si and Ge, having the same crystal structure, we found that the lithiation of crystalline Si is highly anisotropic but the lithiation of crystalline Ge is almost isotropic. HRTEM imaging of the atomic-scale lithiation processes reveals the root cause of this difference. In addition, this presentation will demonstrate that the synergistic integration of in-situ HRTEM and multiphysics modeling provides a powerful means to advance the fundamental understanding of the lithiation/delithiation mechanisms, shedding new light onto the development of durable electrodes for high performance Li-ion batteries.
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Two-dimensional early transition metal carbides or carbonitrides, MXenes, are promising as a new class of energy storage materials for applications such as anodes in lithium-ion batteries or electrodes in electrochemical capacitors. Their two-dimensional structures, which contain more than one element, can offer comparable or even superior properties, in comparison with graphene, due to tunable compositional variables. To better understand their performance and develop their applications, their stability in air and oxidation behavior need to be investigated. In this research, we characterized oxidation of multilayered Ti3C2 under pure oxygen environment at different pressures, inside transmission electron microscope (TEM) using an environmental TEM holder.
Two-dimensional Ti3C2 particles were transferred onto the bottom chip of the environmental cell and then the temperature was increased to initiate the oxidation process under different oxygen pressures. Real-time observation of structural evolution was captured by high-resolution imaging and diffraction patterns. Formation and growth of anatase nanoparticles, as a result of oxidation, was identified. This study can further reveal the underlying mechanism of MXene oxidation and titanium oxide formation in order to produce hybrid carbide-oxide materials.

The use of patterned electrodes with well-defined geometric features has emerged as a valuable approach for elucidating electrochemical reaction pathways. The methods are hampered, however, by the need to create individual electrode configurations using lengthy microfabrication approaches and subsequently conduct measurements of many different samples to access a range of geometric features. Furthermore, subtle variations in fabrication steps for samples produced in series can lead to sample-to-sample variations that mask trends with the parameters of interest. Here we address these challenges using a parallel fabrication methodology that allows access to hundreds of dimensionally varied electrodes on a single electrolyte substrate in combination with an automated microprobe measurement system that enables rapid acquisition of electrochemical data from each of these electrodes. Example results are presented for solid oxide fuel cell (SOFC) cathode materials. Scaling behavior of both resistance and capacitance with electrode geometry is presented.

Solid oxide fuel cells (SOFCs) are energy conversion devices that rely on nonstoichiometric oxides to convert chemical energy into electrical energy with higher efficiency and lower environmental impact compared to typical combustion processes. Under the operating conditions of fuel cells, which include high temperatures and large oxygen partial pressure gradients across the cell, these materials may undergo changes in lattice parameter due to differences in the level of nonstoichiometry within the material, a phenomenon known as chemical expansion. This chemical expansion can also affect the mechanical properties, such as the Young's elastic modulus E, of these oxides. Pr_xCe_1-xO_2-δ (PCO, where δ represents oxygen vacancy content) is a model SOFC cathode material that displays significant nonstoichiometry in air at high temperatures. The magnitude of E for thin films of PCO is measured at room temperature for several compositions, establishing that Pr-content alone in this mixed ionic-electronic conducting system does not impact E. Through the use of environmentally controlled instrumented indentation at high temperatures relevant to SOFC operation (>500 °C), the effect of nonstoichiometry on the magnitude of E of PCO thin films is measured in situ, and the relative impact of thermal and chemical expansion on E are discussed. The consequences of such stiffness variation with temperature for more durable, portable SOFCs are considered.

In order to meet emerging electrical energy storage challenges, novel devices such as electrochemical double layer capacitors (EDLCs), or supercapacitors, are rapidly attracting interest. They rely on electrosorption of ions by porous carbon electrodes and offer a higher power and a longer cyclic lifetime compared to batteries. Room temperature ionic liquids (RTIL) are gaining increasing interest to further enhance the systems&’ operating voltage windows and charge storage densities. These electrolytes can broaden the operating voltage window and increase the energy density of EDLCs. While they may offer multiple performance advantages, the dynamic processes that govern their mobility in and out of pores, long-range transport, and differential behavior in a neat or solvated state are not thoroughly understood. Our work presents direct measurements of ion dynamics of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm-TFSI) in an operating EDLC with electrodes composed of endohedral nanosized carbide-derived carbons (CDCs) and exohedral onion-like carbons (OLCs) with the use of in situ infrared spectroelectrochemistry. For CDC electrodes, absorbance measurements correlated charging and discharging of EDLCs with RTIL ions (both cations and anions) entering and exiting CDC nanopores. Conversely, for OLC electrodes, ions were observed in close proximity to the OLC surface without any change in the bulk electrolyte concentration during charging and discharging of the EDLC. This provides experimental evidence that charge is stored on the carbon surfaces of OLC EDLCs without long-range ion transport through the bulk electrode, contradicting the traditional wisdom of diffusion-driven ion mobility. Systems of RTIL ions solvated using organic propylene carbonate (PC) solvents showcased ion-dominated mobility in and out of confined porous architectures, excluding PC from the nanopores and corroborating the expected desolvation of electrolyte components in systems with matching ion/pore diameters. The experimental measurements presented here provide deep insights about the molecular level transport of RTIL ions in EDLC electrodes that will impact the design of electrode materials. This in situ technique, which can be applied to a wide range of electrochemical systems, is essential towards understanding ion mobility and selecting the optimal electrode/electrolyte configurations for novel electrical energy storage systems.

This study demonstrates the use of the in-situ spectroscopy for the characterization of spontaneous dehydrogenation reactions and being a tool to investigate possible routes of stabilization and control of thermodynamically unstable species. The corresponding results give crucial parameters helping to properly tune the properties of materials for energy storage applications.
Metathesis and reactive milling are established methods to synthesize new compounds for energy storage materials. In many cases, intermediates and/or products formed are thermodynamically unstable. Their characterization and measurement as a function of time and temperature is a key problem for technologic transfer [1].
We demonstrate the formation of intermediate species, studying one of the most promising materials for hydrogen storage, LiBH₄, and specifically the reaction:
TiCl₃ + 3 LiBH₄ → Ti(BH₄)₃ + 3 LiCl → 3/2 B₂H₆ + 1/2 H₂ + TiH₂ + 3 LiCl
The identification and characterization of Ti(BH₄)₃ is a technical issue because it is extremely reactive in air, spontaneously decomposes within few hours at room temperature and it is volatile. Therefore the combination of different in situ techniques is required. The bulk analysis by Thermal Desorption Spectroscopy and Thermogravimetric Balance gives insight on the thermodynamic properties of the reaction products; the surface analysis by Raman Spectroscopy, Mass Spectroscpy and X-ray Photoelectron Spectroscopy gives insight on the chemical composition; the gas phase analysis by Infra-Red Spectroscopy gives insight on the volatile reaction products [2].
Moreover the formation of unstable intermediate species might catalytically act on the kinetics of the overall reactions and yield to the emission of unwanted side products. To control and exploit new materials for energy storage the complementary results of the presented in situ analyses are necessary.
In addition, the thermodynamycal unstability of the intermediate species is a challenge for in situ spectroscopy because of their short life time: for some reactions these intermediate species have been theoretically predicted but never experimentally shown. To address this challenge, spontaneous release of hydrogen from mixtures of LiBH₄ with AlCl₃ [3], ZnCl₂, CuCl₂ and VCl₂, will be analyzed. A comprehensive bulk, surface and gas phase analysis of the reactions products and eventually formed intermedaite species will be presented, pointing out the route towards the control of spontaneous dehydrogenation reactions and the stabilization of the intermediate species.
References
[1] E. Callini, et al., Dalton Transactions 42, 719 (2013).
[2] A. Borgschulte, et al., J. Phys. Chem. C 115 (34), 17220 (2011).
[3] I. Lindemann, et al., Int. J. of Hydrogen Energy 38, 2790 (2013).

Characterization of catalytic reactions is often hindered by the fact that the behavior the system is mesoscopic, while the materials involved are nanoscale, with features that can span a broad range of temporal and spatial scales and which involve a broad range of competitive interactions. As a result, the description of a catalytic system requires interrogation with a variety of techniques - involving imaging, diffraction and spectroscopy - to describe the dynamic changes in structure that can occur during reactions. Commonly, this is done by simple use of standard techniques, and inference of how the results relate to the working condition of the system. It is, however, preferable that multiple probes are used to characterize physical and electronic structure of the catalyst during reaction, over multiple time and length scales. To date it has not been possible to directly link the observations across these techniques in such a way as to confirm that the data (imaging, diffraction, spectroscopy) is obtained from the system in the exact same “working” state.
Here we report an experimental approach that allows:
#9679; characterization - via x-ray absorption spectroscopy, extended x-ray absorption fine structure, x-ray fluorescence, Raman spectroscopy, transmission electron microscopy, scanning transmission electron microscopy, electron energy loss spectroscopy and energy dispersive electron microscopy - from the same sample,
#9679; characterization at atmospheric pressures in reactive environments, and
#9679; simultaneous, real-time and on-line analysis of the reaction products - i.e. “operando” experimentation

We take advantage of recent developments in sample holders for transmission electron microscopy that allow catalysts to be confined between two, thin nitride membrane supports that are separated by a narrow gap, and that allow continuous flow of liquid or gas through the system. We exploit the simplicity of this system in such a way as to allow utilization in both synchrotron x-ray beamlines and transmission electron microscopes. We have chosen a simple, model catalyst reaction for the demonstration phase of this work, the catalyzed conversion of ethylene to ethane, though the use of Pd/SiO2 and Pt/SiOnot;2 heterogenous catalysts. This reaction occurs at room temperature, thereby greatly simplifying the initial experimentation. We demonstrate the ability to measure reactive products in this system, and demonstrate that the measurements made in each technique are from the same “working” catalytic system. The combination of measurement approaches allows us to directly correlate “ensemble-average” properties (such as can be obtained with x-ray absorption and Raman approaches) with measurements of individual particles, at the atomic scale. Extension to high-temperature experimentation will be reported, thereby demonstrating the extension of this approach to the full class of catalytic systems. We will describe how this technique will be improved with the presence of ‘first light&’ at the new National Synchrotron Light Source - II at Brookhaven National Laboratory, a third generation light source with dedicated beamlines for micro- and nano-fcoused imaging and spectroscopy.

References:#8232;
[1] Research carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. Y.L and A.F.F acknowledge additional support through the Synchrotron Catalysis Consortium, U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-FG02-03ER15476.

The ability to tune the size, composition, shape, and surface properties of nanoparticles is important for achieving high performance of nanocatalysts in energy storage and conversion. The development of this ability requires understanding of the detailed structural evolution in the actual catalyst treatments and catalytic reaction processes. This report describes recent findings of an in-situ high-energy x-ray diffraction (HE-XRD) study of Pt-based binary and ternary alloy nanoparticles in catalytic oxidation reaction of carbon monoxide. Synchrotron x-ray sources were used. An intriguing trend of catalytic activity of the catalysts for CO oxidation was revealed, exhibiting Ternary > Binary > Pt. The HE-XRD coupled to atomic pair distribution function analysis (PDFs) and reverse Monte Carlo simulation were used for the detailed structural characterization. The in-situ HE-XRD/PDFs monitoring of the structural evolution of the nanoalloys in the oxidative - reductive thermochemical treatment revealed an intriguing lattice expansion and shrinking characteristics, which depends on the chemical nature composition of a second or third metal added in the Pt-nanoalloy. The 3D modeling of the data provided useful information for assessing the chemically disordering or ordering or metal-enrichment behavior under different thermochemical conditions.

In-situ X-ray Absorption Fine Structure (XAFS) combined with Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) experiments will be carried out to determine the structural changes of gold on ceria (Au/CeO2) catalyst under “transient” conditions for the water-gas shift (WGS) reaction. The oxidation of gold (Au(0),Au(I) or Au(III)) will be traced by XANES (Au L-III edge, 11.9 KeV) under fluorescence mode. The chemical bonding between Au and CO (e.g. Au0-CO or Au+-CO) on the oxide surface will be monitored by DRIFTS. The time-scale for each technique will be less than 3-4 min for XAFS and less than 1 min for DRIFTS, respectively. The simultaneous XAFS/DRIFTS measurements will provide the fingerprints on gold chemistry. The related “transient” conditions, realized by the use of multi-position switching valve, will build the relationship between the eletronic structure of low-concentration (1 at.%) active metal and the surface interaction with reacting molecules. Meanwhile, the gold catalysts under "transient" conditions will be governed by the chemical reaction only, instead of the diffusion process (mass transfer limination) under "steady-state" conditions. The tested gold catalyst is highly homogenous and well dispersed on the related oxide matrix, which guarantees the specific measuring areas by XAFS (below the surface of sample powders) and DRIFTS (the surface of sample powders) stand for the whole tested catalysts. Therefore, we are expecting that the current combined surface (DRIFTS) and bulk (XAFS) characterizations can be used to give a full scheme on the water-gas shift reaction mechanism in gold-ceria system.

The characterization methods available at today&’s synchrotron light sources are ideally suited to unravel the complexity of a practical working catalyst. This will be illustrated using examples from our work using a combination of synchrotron techniques including: X-ray micro- and nano-tomography, and in situ XAFS combined with density functional theory (DFT) and DFT/MD calculations. The use of in situ XAFS is a powerful catalyst characterization technique as it provides detailed element-specific atomic-level structural and chemical information of the active catalyst. Often this information cannot be obtained by any other method. We have developed and implemented the appropriate equipment to allow these in situ studies to be performed. This equipment ranges from a plug flow reactor that operates at high pressure, to equipment that allows rapid collection of XAFS data from multiple samples simultaneously. Examples of our recent work will be presented. Each example will highlight a different aspect of the use of in situ XAFS in an industrial research environment. These examples will include mirco- and nano-characterization of an FCC catalyst, in situ sulfidation of experimental hydroprocessing catalysts, the use of ligand XAFS as a quick screening method, and operando XAFS of rhenium-based catalysts.

There exists a current necessity in real time in situ (photo-) electron spectroscopy and microscopy under ambient pressure to study the processes taking place at solid-liquid-gas interfaces relevant to energy harvesting/storage, sensing, biomedical applications and etc. To address these needs, advanced differentially pumped electron optics for the electron energy analyzer has been implemented more than a decade ago. In our work, we propose to use quasi-2D materials such as graphene and its derivatives to design electron transparent but molecularly impenetrable windows, which separate UHV environment of the analyser(s) from the sample immersed in gas or liquid environment under ambient pressure. Based on unique combination of graphene&’s electron transparency, mechanical strength and its gas impermeability coupled with well developed graphene transfer protocols, we demonstrate the capability to perform XPS and electron microscopy studies of the processes taking place at liquid-solid interface through graphene-based membranes. In addition, we report on the development and tests of the sample platform that is compatible with standard XPS setups and does not require microsroscopy to probe liquid samples.

Soft-landed, size and composition selected subnanometer Ag clusters are active for the selective partial oxidation of propylene at relatively low temperatures. Activity and selectivity for the creation of propylene oxide vs. acrolein is found to be size and support dependent, determined through the investigation of three cluster sizes between 3 and 20 atoms and three supports (Al2O3, TiO2, and ZnO). Temperature programmed reactivity (TPRx) was performed with in situ synchrotron X-ray characterization, Grazing Incidence Small Angle X-ray Scattering (GISAXS) and X-ray Absorption Spectroscopy (XAS), to determine structural morphology and oxidation state during catalytic activity. The oxidation state of the Agn clusters (XAS) varies significantly due to size and support, the largest clusters exhibit entirely different oxidation state due to the support on which they have been soft-landed. At higher temperatures, changes in size and assembly are observed through GISAXS with marked dependence on support. The aggregates show distinct properties and activity due to being formed from different cluster building blocks and on different supports. Utilizing the presented method of catalyst synthesis and in situ characterization, it is feasible to investigate single active sites without the convolution that occurs in many studies from a range of particles sizes and active sites being present as well as study the aggregates that form at higher temperature and present unique reactivity.
References:
1) Y. Lei, F. Mehmood, S. Lee, J. P. Greeley, B. Lee, S. Seifert, R. E. Winans, J. W. Elam, R. J. Meyer, P. C. Redfern, et al., Science 328, 224-228 (2010)
2) S. Lee, B. Lee, S. Seifert, S. Vajda and R. E. Winans, Nucl. Instr. and Meth. A, 649. 200-203 (2011)
3) L. M. Molina, S. Lee, K. Sell, G. Barcaro, A. Fortunelli, B. Lee, S. Seifert, R. E. Winans, J. W. Elam, M. J. Pellin, et al., Catal. Today 160, 116-130 (2011)
4) S. Vajda, S. Lee, K. Sell, I. Barke, A. Kleibert, V. von Oeynhausen, K.-H. Meiwes-Broer, A. F. Rodriguez, J. W. Elam, M. J. Pellin, et al., J. Chem. Phys. 131, 121104 (2009)

Chemical, solar, and electrochemical energy conversion processes rely on a variety of materials functionalities which include catalysis, light harvesting and charge/mass transfer. Exposing materials to combinations of gas or liquid environments, photon fluxes and electrical biasing may result in surface restructuring, localized or interfacial phase changes or even complete phase transformation. Advances in in situ environmental transmission electron microscopy (ETEM) allow materials to be observed under a wide range of energy relevant stimuli including temperature, gas and liquid environments, light and electrochemical bias. Coupling these in situ approaches with aberration correction and monochromation promises to revolutionize our ability to characterize the local structure and electronic bonding of materials in their working state. Moreover simultaneous measurement of structure and function leads to the so-called operando techniques which attempt to strongly correlate functionality with the active structures.
We are developing a variety of in situ and operando techniques on FEI Tecnai and Titan ETEM platforms targeted at elucidating structure-property relations for materials relevant to catalysis, photocatalysis and solid oxide fuel cell applications. We have recently employed electron energy-loss spectroscopy and mass spectrometry to detect gas phase catalytic products directly inside the ETEM while performing atomic resolution image [1]. This provides an operando approach to catalyst characterization in which catalyst structure can be directly correlated with in situ measurements of catalytic activity. By installing a light source in the ETEM we have been able to investigate changes taking place in photocatalysts during vapor phase water splitting [2, 3]. We are currently extending this approach using liquid cells. A recently delivered NION UltraSTEM has delivered energy resolution below 20 meV in electron energy-loss spectroscopy. This provides additional capability to probe electronic structure including bandgap mapping, surface plasmon resonances and adsorbate structures.
[1] Chenna S., and P.A. Crozier, (2012) ACS Catalysis 2: 2395-2402.
[2] Miller, B. K., Crozier, P. A. (2013), Microscopy and Microanalysis, 19 461-469.
[3] Zhang, L. X., Miller, B. K., Crozier, P. A. (2013), Nano Letter, 13 679-684.
[3] The support from the National Science Foundation (NSF-CBET 1134464), US Department of Energy (DE-SC0004954) and the use of TEMs at the John M. Cowley Center for High Resolution Microscopy at Arizona State University are gratefully acknowledged.

Recent progress made in transmission electron microscopy is beneficial for the study of heterogeneous catalysts used in energy and environmental technologies. Advancements in electron optics have made transmission electron microscopy of catalysts available with atomic resolution and sensitivity, and parallel developments in gas cells enable in situ observations of catalysts during the exposure to reactive gas environments of up to atmospheric pressure levels and several hundred degrees Celsius. It is desirable to take advantage of such emerging instrumentation and imaging methodologies to uncover the dynamic behavior of heterogeneous catalysts and to improve the understanding of structure-sensitive catalytic functionality. In this presentation, I will outline work that exploits transmission electron microscopy to monitor catalysts in situ and discuss how such dynamical observations can be used to elucidate the role of gas-surface interactions on the working catalyst, e.g. (1-8).
1. C.F. Kisielowski et al, Angew. Chemie Int. Ed. 49, 2708 (2010).
2. L.P. Hansen, Q.M. Ramasse et al. Angew. Chemie. Int. Ed. 50, 10153 (2011).
3. J.R. Jinschek, S. Helveg, Micron 43, 1156 (2012).
4. J.F. Creemer et al, Ultramicroscopy 108, 993 (2008).
5. S.B. Vendelbo et al, Ultramicroscopy, in press (2013).
6. S.B Simonsen et al, J.Am.Chem.Soc. 132, 7968 (2010); J. Catal. 281, 147 (2011).
7. S. Saadi et al, J.Phys Chem. C 114, 11221 (2010).
8. Z. Peng et al. J. Catal. 286, 22 (2012).

Silver thin films are used as a functional layer in many applications such as low-emissivity and solar control coatings on glass for insulating windows, as well as transparent conducting electrodes for OLEDs and PV. For these applications, the conductivity of the film is critical; it is linked to the crystallinity and the grain size of silver layers which thickness ranges from 5 to 15nm. Such coatings often undergo thermal treatments up to 700°C aimed at toughening the glass substrate or improving the coating itself by promoting grain growth and curing point defects. This treatment can however dramatically damage the silver layer by inducing the formation of defects in the layer, such as holes or silver domes, decreasing both conductivity and light transmission of the coatings.
Because of the extreme thinness of the films (less than 15 nm), the investigation of these phenomena requires in situ imaging at the nanoscale. In this study, grain growth and defects formation were observed in 15 nm-thick Ag films encapsulated with zinc oxide and silicon nitride using Transmission Electron Microscopy with in-situ heating from ambient temperature to 600°C. Significant grain growth was found to occur only from 400°C, and from 500°C holes in the silver layer started to form and grow, as well as thick silver domes formed by dewetting. Irradiation by the electron beam was also found to cause grain growth.

Atomic level understanding of metal surfaces under environmental conditions is critical for developing a structure-property relationship in a range of scientific disciplines, including materials science, catalysis or solid-state physics to name few examples. In this work, we will present atomic-level in-situ TEM observations of oxidation of Pd nanoparticles supported by model and high-surface-area substrates. The in-situ Transmission Electron Microscopy observations were performed with environmental FEI Titan 80-300 equipped with a CEOS Cs -image corrector operated at 80kV and 300kV. The imaging was performed in the presence of reactive gases of up to ~10 mbar, and the samples were heated with MEMS based AduroTM Protochips heating holder. The presentation will focus on the atomic-scale analysis of PdOx formation on Pd-nanoparticles (5-15nm in size) at temperatures 400-500 °C. We will discuss the mechanism of oxide formation and the structural nature of well-defined surface oxide. The detected surface oxide phase PdOx will be placed into perspective with the known Pd oxides. Lastly, we will discuss the electron beam effect and present examples where high dose electron beam is observed to cause structural transformation. This research is part of the Chemical Imaging Initiative at Pacific Northwest National Laboratory. The work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE&’s Office of Biological and Environmental Research and located at PNNL.

Lithium-ion batteries (LIBs) have been used as power sources for mobile devices such as cell phones and mobile PCs because of their large energy densities. In order to enhance LIB performance, it is very important to understand the electrode/electrolyte interface reactions because these reactions greatly affect the cyclability and power density of LIB. However, the mechanisms of such interface reactions have not yet been fully understood due to the difficulty of their direct observation for the reactions at nanoscale. Our group has directly observed the interface reactions of a thin-film model electrode of LiCoO2 by in-situ total-reflection fluorescence X-ray absorption spectroscopy (in-situ TRF-XAS) [1-3].
LiFePO4 shows higher cyclability in terms of capacity during the charge/discharge process than LiCoO2. A higher degree of reversibility of the electronic states at the surface of LiFePO4 is expected during the charge/discharge process. In this work, we have investigated the reversibility of the surface of a LiFePO4 thin-film electrode by using in-situ TRF-XAS.
Cyclic voltammogram of the LiFePO4 thin-film shows a couple of anodic and cathodic peaks, which are characteristic of LiFePO4, were observed at 3.47 and 3.37 V, respectively. During the charge/discharge process, in-situ TRF-XAS were measured by setting the sample angle (0.13°) to detect fluorescence X-ray from the surface region (about 3 nm). After electrolyte, the Fe-K edge XANES spectrum of LiFePO4 did not shift. This result indicates that the surface does not react with the electrolyte. In the case of LiCoO2, Co3+ on the surface is reduced by electrolyte soaking. The difference between the surface XANES spectra of LiFePO4 and LiCoO2 indicates that LiFePO4 surface is more stable than LiCoO2 surface in a reduction atmosphere. In the charge process, the Fe-K edge XANES spectra of LiFePO4 surface exhibited a shift towards higher energy region thereby indicating that the Fe in the LiFePO4 surface was oxidized. When the discharge was proceeded, the XANES spectra shifted towards the lower energy region thereby indicating that the Fe in the LiFePO4 surface was reduced. The XANES spectra before and after the charge/discharge process were well reversed ; this reversal was not observed for LiCoO2. This result indicates that the surface of LiFePO4 is more stable than LiCoO2.
References
1) D. Takamatsu, Y. Koyama, Y. Orikasa, S. Mori, T. Nakatsutsumi, T. Hirano, H. Tanida, H. Arai, Y. Uchimoto, Z. Ogumi, Angew. Chem. Int. Ed., 2012, 51, 11597 - 11601
2) D. Takamatsu, S. Mori, Y. Orikasa, T. Nakatsutsumi, Y. Koyama, H. Tanida, H. Arai, Y. Uchimoto, Z. Ogumi, J. Electrochem. Soc., 2013, 160, A3054 - A3060
3) D. Takamatsu, T. Nakatsutsumi, S. Mori, Y. Orikasa, M. Mogi, H. Yamashige, K. Sato, T. Fujimoto, Y. Takamashi, H. Murayama, M. Oishi, H. Tanida, T. Uruga, H