Fast, safe and low energy consumption charging for lithium-ion batteries via dynamic safety boundaries and adaptive SOC control

The widespread adoption of electric vehicles necessitates lithium-ion batteries capable of fast charging, yet this process inherently faces the risk of heat generation and lithium plating. Considering the common fast charging scenarios around room temperature and practical implementation feasibility, this study introduces an offline multi-stage charging optimization framework. This framework is based on an enhanced electrochemical-thermal coupling model, and the solid-phase diffusion coefficient for both electrodes varies with state of charge (SOC). Leveraging the high rates adaptability and precise dynamic lithium plating current boundary tracking at the negative electrode enabled by this high accuracy model, three systematic charging solutions are developed and thoroughly analyzed. There are two charging strategies based on uniform SOC intervals, corresponding to the fixed safety boundaries without critical charging current update and dynamic safety boundaries with critical charging current update, as well as a charging protocol with nonuniform SOC intervals based on energy consumption. Compared with using traditional fixed safety boundaries, the dynamic boundary strategy maintains negative electrode potential above 10 mV throughout charging to guarantee safety. Further, the energy-adaptive SOC interval division approach extra curtails energy consumption by 1.03% and mitigates power fluctuations, which can deliver substantial cumulative benefits when scaled to the massive electric vehicle market. For low temperature conditions, the batteries can be preheated to specific temperatures before applying the proposed strategy. This framework offers valuable insights into the design of next-generation charging protocols for lithium-ion batteries that are fast, safe, and economically viable.