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

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 (Al₂O₃) and dense carbon on the micron-sized silicon oxide (SiO) particles (SiO@Al₂O₃/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@Al₂O₃/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.