Dual‐Interphase Engineering With Nano‐Alumina and CVD Carbon Enabling High‐Temperature Calendar Aging Mitigation in Silicon‐Oxide Anode

ABSTRACT

The stability of high‐temperature storage in silicon‐based high‐energy lithium‐ion batteries (LIBs) is highly critical in the operation temperature beyond 40°C, typically in tropical and subtropical regions globally. The unexpected stability of high‐temperature storage would lead to severe self‐discharge, which accelerates the decay of remaining capacity, side reaction‐induced electrolyte decomposition, and fire‐hazard risk. To address such issues, a strategy of solid‐state mechanofusion‐chemical vapor deposition (SSM‐CVD) is proposed to construct a dual‐phase nano‐alumina (Al ₂ O ₃ ) and dense carbon on the micron‐sized silicon oxide (SiO) particles (SiO@Al ₂ O ₃ /C), with the purpose of suppressing the self‐discharge behavior induced by charge transfer between graphite (Gr) and SiO in the negative electrode. With the presence of such dual‐phase coating, a stable solid electrolyte interphase has been constructed on both SiO@Al ₂ O ₃ /C and graphite. The electrochemical performance at high‐temperature storage (60°C for 14 days) suggests that the capacity retention reaches 97.81% with a capacity recovery rate of 99.46% in the as‐assembled commercial 18 650 cylindrical cells, which approaches a record‐setting value under the severe high‐temperature storage condition. This work also elucidates high‐temperature failure mechanisms and offers an SSM‐CVD engineering strategy for stabilizing both capacity and safety in silicon‐based high‐energy LIBs.