Construction of hetero-epitaxial nanostructure at the interface of Li-rich cathode materials to boost the rate capability and cycling performances

Lithium-rich cathode materials are considered to be promising candidate cathode materials for the next-generation Li-ion batteries owing to their high specific capacities and low cost. Nevertheless, they still suffer from undesirable capacity loss and voltage decay during cycling. In this work, we propose a facile strategy to coat lithiated transition metal phosphates on the surface of the Li-rich cathode materials. Strikingly, the coated material demonstrates a hetero-epitaxial nanostructure at the interface between the coating layer and the cathode material. Such a coating layer with a unique interfacial structure could effectively boost the Li+ solid-state diffusion kinetics, protect the cathode material from the corrosion of the electrolyte, and suppress the oxygen loss during the charge-discharge processes. Moreover, the lithiated phosphates coating layer can inhibit the formation of the residual Li compounds upon long-term storage under the ambient atmosphere. Based on the above favorable properties, the lithiated phosphates coated Li-rich cathode material achieves a high rate capability with a discharge capacity of 156 mAh g-1 obtained at 5 C and decent cyclic stability with a capacity retention of 93.4% achieved at 0.5 C after 140 cycles. This study investigates the interfacial engineering of the Li-rich cathode materials via the construction of Li+-conductive lithiated phosphates coating layer with a hetero-epitaxial interfacial nanostructure, which may offer an effective way to further improve the electrochemical performances of Li-rich cathode materials.