Tracing the Origins of Calendar Aging in Si-Containing Lithium-Ion Batteries

Lithium-ion batteries (LIBs) with silicon/graphite composite (Si/C) anodes are still facing the challenge of unsatisfactory calendar life, and the specific impact of Si on this issue is largely unknown. Herein, the calendar aging behaviors are quantified across scales and explored in a top-down manner. Batteries with 10 wt % Si/C anodes suffer a 4-fold decrease in the overall lifetime and a 4-5-fold increase in irreversible anode loss. Significant parasitic reactions and solid electrolyte interphase growth occur after 72 h of storage with an oxygen increase of 1.3 times on the anode surface and 26 times in the interphase. The micromorphology and component are analyzed in detail, highlighting remarkable Li₂CO₃ precipitation. Finally, the impact on calendar aging is discussed in both external conditions and internal components. Mitigating the electrolyte decomposition caused by active Si will be key to improving the battery's calendar life.