November 29-December 4, 2015 | Boston
Meeting Chairs: T. John Balk, Ram Devanathan, George G. Malliaras, Larry A. Nagahara, Luisa Torsi
We have developed transformational, and intrinsically safe, all-solid-state Li-ion batteries (SSLiBs), by incorporating high conductivity garnet-type solid Li-ion electrolytes into tailored tri-layer microstructures, by low-cost solid oxide fuel cell (SOFC) fabrication techniques to form electrode supported dense thin-film (~10mu;m) solid-state electrolytes. The microstrucurally tailored porous garnet scaffold support increases electrode/electrolyte interfacial area, overcoming the high impedance typical of planar geometry SSLiBs resulting in an area specific resistance (ASR) of only ~2 Omega;cm-2 at room temperature. The unique garnet scaffold/electrolyte/scaffold structure further allows for charge/discharge of the Li-metal anode and cathode scaffolds by pore-filling, thus providing high depth of discharge ability without mechanical cycling fatigue seen with typical electrodes. Moreover, these scalable multilayer ceramic fabrication techniques, without need for dry rooms or vacuum equipment, provide for dramatically reduced manufacturing cost.Fabrication of supported dense thin-film garnet electrolytes, their ability to cycle Li-metal at high current densities with no dendrite formation, and results for Li-metal anode/garnet-electrolyte based batteries with a number of different cathode chemistries will be presented.
Safe Li-ion battery is critical for success of electric vehicle, and the electrolytes are one of the most important component for the safety of the Li-ion batteries. In this talk, we summarize the research progress of our group on all-solid-state Li-ion batteries and aqueous Li-ion batteries. In all-solid-state Li-ion battery, we report a novel concept of a single-material all-solid-state lithium-ion battery, wherein a single Li10GeP2S12 serves as an electrolyte, an anode, and a cathode, to eliminate the highly resistive interface between the electrodes and electrolyte. The realization of the single-Li10GeP2S12 battery is based on the fact that the Li-S and Ge-S components in Li10GeP2S12 could act as the active centers for lithiation/delithiation as a cathode and an anode, respectively, when electronically-conductive carbon is mixed, while pure Li10GeP2S12 can be used as an electrolyte. This unique concept of a single-material lithium-ion battery can be extended to other solid-state battery systems, providing a new direction for high-power, high-energy, long-cycling solid-state batteries. For aqueous Li-ion battery, we report a new aqueous electrolyte, whose electrochemical stability window was expanded to ~3.0 V. A full Li-ion battery of 2.0 V was demonstrated to cycle over 1000 times in this electrolyte, with nearly 100% Coulombic efficiency at both low (0.15 C) and high (4.5 C) rates.
Over the last decade, Li-ion batteries have begun to dominate several energy storage markets due to the many inherent advantages of Li-ion chemistry. More recently, a new approach to Li-ion battery technology has been investigated—utilizing solid-state electrolytes made of lithium garnet-type ceramics. (e.g. Li7La3Zr2O12 or LLZ) These materials are inherently non-flammable and contain no toxic or reactive fluorine. Importantly, garnet materials like LLZ are electrochemically stable to Li metal (enabling higher energy density batteries), and are also thermally stable and mechanically strong. The main areas challenging the development of all-solid-state Li-ion batteries, however, have been low ionic conductivity and high interfacial impedance due, in part, to poor solid-solid contact. The ionic conductivity of garnet materials has been steadily increasing as new compositions/dopants are discovered and sintering conditions are optimized. However, if a method existed which could provide precise control over the microstructure, both of the issues could be resolved. First, the thickness of the electrolyte separating the two electrodes could be reduced to the order of tens of microns, such that the overall resistance of the bulk electrolyte would become negligible. Secondly, by tailoring the architecture of the contact surface of the electrolyte with the electrode, the interfacial impedance could be similarly reduced.With the recent growth and maturation of 3D printing, such precise control over microstructure is now possible, both for scientific and technical applications. Using a 3D printer armed with devices such as a UV lamp for photopolymer spot curing and a laser for laser sintering, not only can the microstructure of the solid electrolyte be adequately controlled, but the interface with the anode and cathode can be modified as well. This presents a distinctive way of quickly fabricating unique, ordered architectures to address the impedance issues described above. Using a 3D printer, thin solid-state batteries have been printed using different microstructures/architectures for each component to explore the effect of each on battery properties. For example, the aspect ratio has been found to significantly impact the performance metrics. Additionally, using characterization tools such as electrochemical impedance spectroscopy, Raman spectroscopy, and SEM, bulk properties and interfacial effects can be investigated with a high degree of accuracy. In this way, both macro and microscopic spatial variations of structure and composition will be probed.
Solid polymer electrolytes (SPEs) possess an inherent safety advantage over traditional liquid carbonate electrolytes, and can be incorporated into an effective solid-state battery at physiological temperature for use in implantable devices. In this work, we report on our progress towards the goal of the development of a solid-state battery utilizing a SPE. The electrochemical properties of a SPE using a poly(ethylene oxide) (PEO) polymer matrix in the presence of tri-ethyl sulfonium bis(trifluorosulfonyl) imide (S2TFSI) ionic liquid (IL) and lithium TFSI with appreciable ionic conductivity ~ 1 mS/cm at physiological temperature are presented. These homogenous, mechanically robust films were fabricated via a hot-pressing method and incorporated into lithium metal/SPE/lithium cobalt oxide or lithium iron phosphate pouch cells where the cycling performance and rate capability were assessed. The cells were disassembled post-mortem and the SPE/cathode interface was examined using a dual FIB-SEM system whereby FIB was used to expose fresh SPE/cathode interface and SEM was used for imaging and elemental composition analysis.
Lithium-ion batteries (LIBs) are one of the most widely used energy storage devices in modern society, and they are playing important roles in the rapidly developing markets of pure/hybrid electric vehicles and other large-scale energy storage systems. Current LIBs utilize flammable liquid electrolytes, which have brought potential risks, especially for large-scale applications. Moreover, additional problems emerge when moving to advanced systems beyond conventional LIBs, such as lithium-sulfur and lithium-air batteries, where the use of metallic lithium as anode would cause dendrite formation and raise safety concerns regarding short circuit. Solid electrolytes have been considered as feasible solutions to the safety issues of liquid ones.Continuous efforts have been devoted in the past few decades to search new materials for solid electrolytes, which mainly include ceramic-based and polymer-based electrolytes. In this work, a novel class of solid electrolytes with biomimetic ionic channels will be discussed, providing a new direction towards high-performance and robust LIBs.
Thermo-electrochemical cells with aqueous electrolyte that convert low-grade heat (<130 degree Centigrade) directly into electrical energy, has attracted considerable attentions as an alternative strategy to thermal energy harvesting. However, innately poor electrical conductivity of aqueous ferro/ferricyanide electrolyte is one of critical factors to limit the efficiency of thermal-electrochemical cells. In order to enhance electrical conductivity and diffusivity of the electrolyte, applying nanoparticles into the electrolyte which is called electrolyte-based nanofluids can be one of promising ways for the augmentation of mass transport in the electrolyte through the combined effect of percolation behavior and convection. The presence of nanoparticles in electrolyte is seldom studied due to intrinsic instability of nanofluids, especially, in electrolyte with high ionic strength. Moreover, the collocation of base fluids and nanoparticles are strictly restricted by both chemical and physical properties for a stable nanoparticles suspension. Here we report a practicable approach fabricating γ-alumina nanofluid-based ferro/ferricyanide electrolyte equipped with enhanced electrical conductivity and feasible stability by introducing stirred nano-bead milling in conjunction with ultrasonication. Sodium dodecyl sulfate is introduced to stabilize alumina nanoparticles in ferro/ferricyanide electrolyte by constructing steric barriers. 0.2M alumina nanofluid-based ferro/ferricyanide electrolyte holds an ionic concentration 20-fold higher than previous work in the literature, providing practical significance to develop nanofluid-based electrolyte for thermo-electrochemical cells. Based on electrical conductivity and rotating disk electrode studies, the diffusivity of alumina nanofluid-based electrolyte at a nanoparticle mass fraction of 0.25% shows a mutative response to convection, revealing a critical deviation from homogeneous standard ferro/ferricyanide electrolyte at high angular velocities. We decipher this conspicuous increase of the limiting current as a result of both percolation behavior and convection under shear flow. Additionally, alumina nanofluid-based electrolyte i