Research Progress on the Safety of LIBs Separators

Over the years, the electrification of transport has forced improvements in energy storage batteries. Lithium-ion batteries (LIBs) are widely used in aerospace, smart devices, electronic communications, and transport because of their high capacity, good cyclability, and environmental friendliness. However, battery safety is a massive issue in people's daily lives. LIBs occasionally suffer from spontaneous combustion and explosion. This is mainly caused by short circuits within the battery. The diaphragm, as the material separating the positive and negative electrodes, prevents the positive and negative electrodes from coming into direct contact, thus avoiding short circuits. The performance of the diaphragm determines the safety of LIBs. Therefore, this paper first introduces the causes of the thermal runaway of lithium-ion batteries and its relationship with diaphragms. Then, this paper presents the essential characteristics and types of high-safety diaphragms. Finally, this paper also summarises the physical and chemical modification methods of diaphragm materials in LIBs. This will help improve the safety of lithium-ion batteries, increase the electrification of transportation, and eliminate concerns about using LIBs.