Lithium-ion battery high performance cathode electrode based on LiFePO4 and thermal sensitive microspheres with thermal shutdown properties

Abstract

The critical issue of thermal runaway events in lithium-ion batteries (LIBs) is recognized as a primary cause of battery-related accidents. Despite ongoing efforts to enhance LIB safety, challenges persist due to varying chemical compositions, states of charge, and conditions of use across different batteries. To advance battery safety and considering cost and practicality, this research introduces a novel cathode material with thermal shutdown characteristics. Incorporating thermoplastic microspheres into the cathode matrix does not compromise the cathode's structural integrity, but leads to ionic conductivity value reduction, and a consequent reduction of battery performance for the larger microsphere concentrations of 5.0 wt% and 7.5 wt%. On the other hand, the samples demonstrate a thermal shutdown behaviour, triggered by the volumetric expansion of the microspheres, effectively ceasing electrical and ionic conduction, thereby preventing thermal runaway. The cathode with low microsphere concentration, 2.5 wt% of microspheres, outperforms (155 mAh·g−1, at C/8-rate) room temperature battery performance with respect to the conventional cathode and also exhibits thermal shutdown behaviour at 90 °C. The research highlights the potential of integrating expandable microspheres into cathodes for the development of safer batteries, offering a scalable and cost-effective solution compatible with existing battery technologies.