Over‐Lithiation Regulation of Silicon‐Based Anodes for High‐Energy Lithium‐Ion Batteries

Abstract Mitigating the growth of dendritic lithium (Li) metal on silicon (Si) anodes has become a crucial task for the pursuit of long‐term cycling stability of high energy density Si‐based lithium‐ion batteries (LIBs) under fast charging or other specific conditions. While it is widely known that Li metal plating on Si‐based anodes may introduce inferior cycling stability and cause safety concerns, the evolution of the anode/material structure and electrochemical performance with Li metal plating remains largely unexplored. A comprehensive quantitative investigation of the hybrid Li storage mechanism, combining the Li alloying/dealloying mechanism and plating/stripping mechanism, has been conducted to explore the effect of Li plating on Si‐based anodes. The findings reveal that Li plating/stripping accounts for the decay of the overall Coulombic efficiency and cycling stability of the hybrid Li storage mechanism. Furthermore, alloying reactions occurring below 0 V encourage the formation of crystalline Li 15 Si 4 , which subsequently exacerbates voltage hysteresis. The performance decay is amplified as the ratio of Li plating/stripping capacity increases, or in other words, as the over‐lithiation level rises, thereby posing a threat to the battery‘s cycling stability. These results provide valuable insights into the design of advanced Si‐based electrodes for high energy density LIBs.