Enhanced structurally stable cathodes by surface and grain boundary tailoring of Ni-Rich material with molybdenum trioxide

Abstract

Layered nickel-rich transition metal oxides with high energy density are one of the most promising cathode materials for lithium-ion batteries. However, they generally suffer from rapid capacity decay predominantly resulting from the side reactions at the interface between electrode and electrolyte. The conventional surface modification methods adopted for active materials can only partially alleviate the erosion by the electrolyte, with the remaining challenge being the protection of the primary particles inside the material. Here, we report a coating of MoO3 which not only uniformly covers on the surface of secondary particles but also successfully injects into the grain boundaries of primary particles. The latter provides additional Li+ insertion sites that is expected to improve the Li+ diffusion efficiency and cell rate performance. Owing to the MoO3 coating layer which prevents the active material from the electrolyte corrosion, the interfacial side reactions between the cathode and the electrolyte are significantly suppressed. Benefiting from these advantages, the MoO3 infused LiNi0.8Co0.15Al0.05O2 achieves a capacity retention ratio of 91.1% after 100 cycles at 1C rate. This modification method represents a significant progress and is anticipated to be suitable for the research of high-performance cathode materials.