Stress-dependent capacity fade behavior and mechanism of lithium-ion batteries

Understanding the behavior and mechanism of capacity fade in lithium-ion batteries can assist in promoting their wider commercial and industrial applications. We develop an Electrochemical-Thermal-Mechanical coupled Capacity Fade model (ETMCF) for nickel-manganese-cobalt (NMC111)/graphite (C) lithium-ion batteries. The main fade behaviors include SEI formation, lithium plating/stripping, SEI re-formation, and loss of active material. ETMCF model focuses on the influence of stress on capacity fade behaviors, improves the accuracy of predicting battery capacity fade at high charge/discharge rates (C-rates) and a wide temperature domain, and confirms that the stress effect in lithium-ion battery capacity fade is essential and cannot be ignored. We systematically examine the impact of C-rate, operating temperature, and coupling effects on the capacity fade mechanism and discover markedly distinct dominant fade behaviors under various C-rates and temperatures. Moreover, we also construct a phase diagram of the capacity loss ratio and elucidate the dependency of the C-tare, temperature, and capacity loss relationship. This work provides new insights into fast charging strategy and temperature regulation in battery management systems and offers a comprehensive analytical framework for predicting and evaluating battery capacity fade.