Formation mechanism and removal strategy of residual lithium compounds on nickel-rich cathode materials

Lithium-ion batteries employ Ni-rich layered oxides as cathodes because they have a high specific capacity and are relatively inexpensive. Despite this, materials have poor air storage stability because of their high sensitivity to air, and it is easy for lithium compounds to accumulate on their surfaces. As a result, surface residual lithium compounds Ni-rich cathode materials will reduce their comprehensive properties, complicate the subsequent electrode manufacturing process, and severely limit their practical application. Hence, the study of surface removal of residual lithium compounds has great practical significance. A summary of the sources of surface residual lithium compounds of Ni-rich cathode materials is presented hereof, along with an evaluation of the adverse effects those compounds have on materials, and an analysis of feasible solutions to reduce or eliminate these compounds. Finally, a future research direction is discussed for eliminating residual lithium compounds.