A Novel Safety Design Strategy to Improve the Safety Performance of LIBs

A double-layer structured cathode has been generated with a layer of lithium iron phosphate (LFP) coated on top of a layer of LiNi x Co y Mn1‑x‑y O2 (NCM). With the double-layer structure, the thermal stability of the cell has been improved significantly. Not only has the heating generation been reduced greatly but also the decomposition temperature of the NCM layer has been shifted to 302 °C, which is higher than that for the cell with a bare NCM cathode. Meantime, the LFP coating layer can also suppress the occurrence of the severe internal short circuits during the nail penetration test. Therefore, the double-layer structure cathode design is an effective way to improve the safety performance of NCM lithium-ion batteries by using a higher thermal stability coating.