Temperature–responsive coating endowing LiNi0.8Co0.1Mn0.1O2 cathode materials with improved cycling stability and overheating self-protection function

The critical challenges of the commercial application of Ni–rich layered LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode materials for lithium ion batteries are their poor cycling stability and terrible safety. The safety concerns are mainly caused by the thermal runway of the battery started from the battery overheating. Here, we report a temperature–sensitive reversible switching material that is coated on NCM811 cathode materials surface, which simultaneously endows NCM811 cathode materials with improved cycling stability and overheating self-protection function. This coating layer could isolate the bulk cathode materials from the electrolyte, alleviate the structure destroy and suppress the side reactions on the cathode-electrolyte interface, thus enhancing the cyclability of NCM811 cathode materials. Besides, the coating layer endows the every active NCM811 particle with overheating self-protection function, which can block off the electrons transfer between NCM811 and neighboring particles under the overheating conditions and thus switch off battery reactions, preventing the battery from further generating heat and avoiding the occurrence of thermal runaway. Furthermore, NCM811 with this coating layer after switched off is able to resume their normal function. This work attempts to resolve these two critical problems of the application of NCM811 cathode materials, providing a new opportunity for the large-scale commercialization of it.