Unexpected stable cycling performance at low temperatures of Li-ion batteries with Si/C anodes

The durability of lithium-ion batteries (LiBs) is a crucial factor for advancing market applications. Although remarkable progress is achieved in cycling stability at ambient temperatures, the rapid capacity decay at low temperatures (LT) limits their utilization in extreme conditions. This study reveals that LiBs with silicon/graphite (Si/C) anodes exhibit superior LT performance compared to conventional graphite-based anodes. The electrochemical analysis demonstrates that Si improves the LT kinetic performance. In addition, the higher potential plateau of Si thermodynamically prevents the anode from easily reaching the lithium (Li) plating potential. The pronounced expansion of Si and the corresponding thicker solid electrolyte interphase (SEI) at the LT are demonstrated by various characterization techniques, especially the X-ray photoelectron spectroscopy depth profiling analyses. Li plating is confirmed as the main degradation factor at LT rather than Si swelling. Instead, the addition of Si effectively inhibits anode Li plating, contributing to outstanding LT cycling stability. Furthermore, guidance on the Si/C hybrid strategy is provided through simulations. This study provides a valuable strategy for improving LiB performance at LTs, and promotes the application in extreme conditions, such as in space and the deep sea.