A review on doping/coating of nickel-rich cathode materials for lithium-ion batteries

Nowadays, lithium-ion batteries (LIBs) are widely applied in many fields, in order to reduce the material cost, increase volumetric/gravimetric energy density, raise safety performance and so on, nickel-rich cathode materials have gained much attention. Besides the technique for preparation of precursors and corresponding cathode materials, bulk doping and surface coating are very important to strengthen the performance of nickel-rich cathode materials. However, the intrinsic mechanism of doping and coating for cathode materials is not fully understood, further extensive and intensive investigation is needed. In this article, the varieties of doping and coating are reviewed, and research status, recent progresses and their underlying mechanism are presented. The paper suggests that combination of coating and doping at the same time is crucial to effectively improve the internal and external structure as well as electrochemical performance of nickel-rich cathode materials. Moreover, the present problems and challenges to nickel-rich cathode materials are put forward, the issues of safety and capacity fade of nickel-rich cathode materials are urgently need to resolve, which are closely related to the interface damage, volumetric change, lattice internal strain and gas release during cycling process.