Force-signal driven real-time lithium plating detection in mechanically constrained LiFePO4 pouch cells

Rapid charging technology aims to improve the charging efficiency and reduce the charging time of lithium-ion batteries (LIBs). However, during rapid charging, an imbalance between lithium-ion insertion and extraction may induce lithium plating, leading to capacity fade, increased internal resistance, and potentially internal short circuits and thermal runaway. Thus, real-time detection of lithium plating is critical for battery safety. Traditional voltage relaxation methods require resting periods, resulting in slow detection and limited sensitivity. In this study, we explore the relationship between internal lithium plating and external expansion force using a three-electrode pouch cell. Experimental results reveal that upon lithium plating, the anode potential drops below 0 V; a distinct inflection appears in the expansion force during constant voltage charging, and a peak emerges in the differential pressure curve during constant current charging. Based on these findings, we introduce a novel real-time lithium plating detection technique, termed Differential Pressure Analysis in the Voltage (DPAV) stage. This method circumvents the need for prolonged resting periods or constant voltage charging data, and it delivers higher detection accuracy compared with conventional voltage relaxation and dP/dQ analyses, offering a practical solution for the rapid charging of LIBs.