Lithiation Induced Stresses and Interfacial Phenomena in Li Ion Battery Electrodes
Brian Sheldon (Brown University), Anton Tokranov (Brown University), Ravi Kumar (Brown University), Xingcheng Xiao (General Motors), Peng Lu (General Motors), Yue Qi (General Motors R&D), Mark Verbrugge (General Motors)
Lithium ion batteries: When Chemistry meets Mechanics
Mon 2:40 - 4:00
Salomon 003
Lithiation and delithiation processes in Li ion battery electrodes lead to volume changes that can induce significant stresses. In these materials, interfacial stability is critical for long cycle life. However, it is often difficult to investigate interface mechanisms directly in complex electrode microstructures that consist of powdered active components, conductive filler, and binders. Thin films provide an opportunity to investigate fundamental processes more directly. To accomplish this, we have employed in situ stress measurements, conventional in situ electrochemical measurements, and ex situ surface characterization with TEM, XPS, and SIMS. Research efforts on two general problems will be presented. The first uses patterned Si films as a model composite system, to study the response of bimaterial interfaces during Li cycling. An important finding from this work is that interfaces can be engineered to accommodate large volume changes in the Si during Li insertion and removal. Another area of interest is the solid-electrolyte interphase (SEI) layer, where we have recently shown that substantial near-surface stresses occur during SEI formation on graphitic carbon anodes. These results suggest that stresses can be engineered during SEI formation, to enhance the stability of these critical passivation layers.