Next Generation Materials for Rechargeable Batteries: Molten Salt-Mediated Growth and Gas-Phase Surface Treatments
Abstract: Molten salts electrolytes enable electrodeposition of high-performance lithium and sodium battery cathodes at temperatures around 3000C as well as the concurrent electro-dissolution of used cathodes and electrodeposition of new cathodes. Via electrodeposition, we have grown thick and dense LiCoO2, NaCoO2, LiMn2O4, and other related LTMO cathodes which provide near-theoretical capacities, good rate performances and long cycle lives. Via control of the electrodeposition parameters, including the molten salt electrolyte chemistry, deterministic synthesis of textured thick (>10 µm) films of with iso-oriented crystalline domains having controlled size dispersity and interfaces is demonstrated. When cycled, the properly oriented electrodes exhibit good capacity retention and good rate performance, even at high loadings while electrodes with randomly oriented crystalline domains fail quickly. Since the electrodeposited cathodes are ~95% dense, binder-free and conductive-additive free, they provide a 1.25x to 1.5x increase in the electrode level volumetric energy density compared to conventional slurry cathodes. The controlled surface area and surface crystallographic presentation makes these electrodes particularly amenable to gas-phase surface treatments which enhance high voltage operation. Finally, we show that these nearly single crystal cathodes enable fabrication of solid-state batteries which operate under very low stack pressures at room temperature.
Bio: Prof. Paul V. Braun is the Director of the Materials Research Laboratory, the Grainger Distinguished Chair in Engineering, and Professor of Materials Science and Engineering, Chemistry, Mechanical Sciences and Engineering, and Chemical and Biomolecular Engineering at the University of Illinois Urbana-Champaign. Prof. Braun received his B.S. degree with distinction from Cornell University, and his Ph.D. in Materials Science and Engineering from the University of Illinois. Following a postdoctoral appointment at Bell Labs, Lucent Technologies, Prof. Braun joined the faculty of the University of Illinois. Prof. Braun is a Fellow of the Materials Research Society, AAAS, the National Academy of Inventors, and the American Academy of Arts and Sciences.