In Situ Inducing Spinel/Rock Salt Phases to Stabilize Ni-Rich Cathode via Sucrose Heat Treatment

Abstract

Nickel-rich cathode materials have attracted widespread interest due to their high capacity; however, the structure is prone to degradation and collapse during cycling, resulting in poor stability performance and safety, hindering the development of high-nickel cathode materials. Here, we propose a straightforward method to consume oxygen on the surface of primary particles during the high-temperature calcination process of precursors, inducing the coupled rearrangement of surface cations, resulting in the in situ generation of a nano-sized mixed spinel/rock salt defect phase, which is confirmed by high-angle annular dark-field scanning transmission electron microscopy. LiNi0.8Co0.1Mn0.1O2 modified with mixed phase not only can reduce side reactions with the electrolyte, resulting in fewer by-products such as LiF and Li2CO3, preventing the formation of excessively thick cathode–electrolyte interface layers, but also can avoid irreversible phase transitions and prevents lattice mismatches. As a result, the cycling performance has been improved to some extent, benefiting from structural stability. In addition, the special 3-dimensional structure of the spinel phase allows the material surface to expand ion transport channels and enhance multiplicative performance. Therefore, this study provides a new perspective on the modification of high-nickel materials and extends the application of nickel-rich materials.