Overcharging Characteristics of High‐Power LiFePO ₄ Battery

Against the high‐power application backdrop of lithium‐ion batteries (LIBs), issues like severe temperature rise from rapid high‐current discharge (triggering safety concerns) and energy density loss due to excessive high‐power enhancement lead to distinct material systems/manufacturing processes between high‐power and conventional LIBs. This investigation analyzed aging and thermal runaway (TR) behaviors of high‐power lithium iron phosphate (LFP) batteries under overcharge. At 1C discharge, mild initial overcharge minimally affected internal resistance/capacity but accelerated high‐rate discharge capacity fading; increased overcharge intensified capacity degradation and voltage drop, with aging initially dominated by lithium‐ion loss. Disassembling 1C constant‐current overcharged batteries and analyzing voltage curves identified five reaction stages: overcharge lag, stable delithiation, electrolyte oxidative decomposition, LiFePO 4 /electrolyte depletion, and short‐circuit. TR involved stage‐specific voltage/temperature variations (high peaks) without ignition/explosion. These confirm high‐power LFP batteries’ overcharge tolerance, supporting prospects in integrated energy storage systems (IESS).