Flexible bidirectional pulse charging regulation achieving long-life lithium-ion batteries

Abstract

Typical application scenarios, such as vehicle to grid (V2G) and frequency regulation, have imposed significant long-life demands on lithium-ion batteries. Herein, we propose an advanced battery life-extension method employing bidirectional pulse charging (BPC) strategy. Unlike traditional constant current charging methods, BPC strategy not only achieves comparable charging speeds but also facilitates V2G frequency regulation simultaneously. It significantly enhances battery cycle ampere-hour throughput and demonstrates remarkable life extension capabilities. For this interesting conclusion, adopting model identification and postmortem characterization to reveal the life regulation mechanism of BPC: it mitigates battery capacity loss attributed to loss of lithium-ion inventory (LLI) in graphite anodes by intermittently regulating the overall battery voltage and anode potential using a negative charging current. Then, from the perspective of internal side reaction, the life extension mechanism is further revealed as inhibition of solid electrolyte interphase (SEI) and lithium dendrite growth by regulating voltage with a bidirectional pulse current, and a semi-empirical life degradation model combining SEI and lithium dendrite growth is developed for BPC scenarios health management, the model parameters are identified by genetic algorithm with the life simulation exhibiting an accuracy exceeding 99%. This finding indicates that under typical rate conditions, adaptable BPC strategies can extend the service life of LFP battery by approximately 123%. Consequently, the developed advanced BPC strategy offers innovative perspectives and insights for the development of long-life battery applications in the future.