Determining Operating Boundary of Batteries for Enhanced Longevity With Multiscale Stress Modeling

Fast charging of lithium-ion batteries (LIBs) is a fundamental technology for the broad adoption of electric vehicles. However, unrestricted fast-charging approach may accelerate degradation in LIBs, such as the loss of active material caused by mechanical damage. This paper introduces a new multiscale electrochemical-mechanical model for LIBs, capable of accurately predicting their mechanical behavior. Leveraging this model, novel stress-regulated safety current boundaries are proposed for the first time, ensuring the fast charging while safeguarding the expected lifespan of LIBs. The proposed real-time optimization strategy for safety current boundaries can consistently maintain the maximum allowable current without violating the stress limit. Experimental results indicate that the stress-regulated strategy effectively mitigates the loss of active material in anode induced by over-stress during the high-rate charging. Notably, the proposed strategy reduces charging time by 16.8% compared to the standard constant-current charging, without compromising cycling stability.