Micro-overcharge driven nonlinear degradation mechanisms: Towards early detection of capacity knee points in lithium-ion batteries

Predicting capacity decay in lithium-ion batteries is challenging, especially with nonlinear degradation patterns. This study introduces a novel approach by investigating the capacity decay characteristics of lithium-ion batteries under prolonged micro-overcharging, revealing distinct peaks in the incremental capacity (IC) curve indicative of accelerated cathode material degradation. Furthermore, we propose the Micro-Overcharge Differential Incremental Capacity (MO-DIC) method, a pioneering technique for predicting the capacity decay knee point. MO-DIC uses the rate of change of normalized peak height in the differential overcharging IC curve as a predictive indicator. Validated with low N/P ratio batteries, MO-DIC forecasts the life inflection point 25 to 36 cycles ahead of capacity fade indicators and approximately 50 cycles before end-of-life. This innovative approach markedly improves battery health status prediction, offering substantial benefits for battery life cycle analysis and proactive maintenance strategy formulation. Future work will refine the MO-DIC method and evaluate its applicability across diverse battery types and operating conditions.