Novel heat storage ionomer binder for thermal management of Li-ion batteries

Abstract

Lithium-ion batteries (LIBs) are promising for power batteries because of their high energy density and working voltage, but the high accident rate caused by the flammable electrolyte and constantly accumulating heat scares consumers and restricts their market. Herein, a novel heat storage ionomer binder (HSIB) with highly efficient heat-storage ability is proposed to function as an internal temperature conditioner, which can effectively store heat and accommodate temperature rise, allowing the battery to function steadily over a wider temperature range while not significantly increasing the weight or volume of the battery. A nail test and thermal simulation demonstrate that HSIB can decrease the temperature rise of the cell by about 30% and reduce the risk of thermal runaway due to the heat storage ability of the polyethylene glycol (PEG) main body. The assembled LiFePO₄ (LFP) cell with HSIB shows lower polarization (ΔV decreased by 25 mV over PVDF) in a CV test owing to fast Li⁺ diffusion pathways constructed by the binder, and extra capacity and higher capacity retention of 14.38% are achieved. Moreover, an LFP cell with HSIB shows good thermal endurance in a designed temperature variation test, suggesting that HSIB offers a novel practical solution for battery safety.