How to improve the energy density of lithium-ion batteries has always been the core content of lithium-ion battery research, especially in the aspect of cathode materials. In order to improve the specific energy, people are "unscrupulous". Therefore, a variety of cathode materials for lithium-ion batteries are emerging one after another, such as lithium rich manganese, ternary materials, etc. The specific capacity of some cathode materials has reached more than 200mAh/g, However, these cathode materials o