Recent advance into understanding electro-chemo-mechanical behavior of lithium ion batteries by electron microscopy

Abstract The amount and kinetics of intercalation and extraction of electrons and ions in electrodes is critical for high-performance Li-ion batteries (LIBs), which are rather complicated involving tight interactions of both electrochemistry and mechanics. These coupled electro-chemo-mechanical behaviors could substantially influence the number and kinetics of transferred ions and electrons and ultimately affect the performance of the entire battery system. Furthermore, the emerged surface/interface coating–engineered electrodes in both cathode and anode materials can significantly regulate the performance of batteries, while the underlying mechanism should urgently be unveiled. With the capability of resolving the structure and chemistry, advanced electron microscopy is an ideal technique for directly visualizing the interplay between electrochemistry and mechanics in both neat and modified electrode materials at atomic-to-bulk scale. This review first summaries recent progress in electron microscopy regarding electro-chemo-mechanical behaviors of both anode and cathode materials, which includes techniques of in situ/ex situ (scanning) transmission electron microscopy and scanning electron microscopy. In addition, as a comparison, the electron microscopy of how surface/interface coatings regulated electrodes is further represented. Finally, the major challenges and opportunities of electron microcopy techniques are outlined for rechargeable ion batteries. An in-depth understanding of the electrochemistry-mechanics interaction in electrodes could describe the full mechanism that governs the Li-storage performance and then provide fundamental guidelines for target-oriented LIB design and optimization.