Stress-Regulated Protocols for Fast Charging and Long Cycle Life in Lithium-Ion Batteries: Modeling and Experiments

To accelerate charging without rapid degradation, fast charging protocols that regulate stress are theoretically and experimentally investigated. In the stress-regulated protocol, the diffusion-induced stress within the active particle rapidly reaches a critical value in the early stage of charging and maintains that value throughout the charging process. To resolve the issue of the theoretically infinite current at the beginning of the stress-regulated protocol, a modified method that contains an initial constant-current stage followed by a stress-regulated stage is proposed. The key parameters are identified from the governing equation and can be easily obtained via constant-current charging tests. The modeling and experimental results collectively suggest that the proposed protocol considerably shortens the charging process (10%–20% compared with the referenced constant-current protocol) without sacrificing cycling stability and capacity utilization. The proposed protocol appears superior to other fast charging protocols (including high-rate constant-current charging, boost charging, and exponential current charging) in achieving a balance of charging speed and cycling performance.