Enhancing structure and cycling stability of Ni-rich layered oxide cathodes at elevated temperatures via dual-function surface modification

High-nickel single-crystal layered oxide material has become the most promising cathode material for electric vehicle power battery due to its high energy density. However, this material still suffers from structural degradation during cycling and especially the severe interfacial reactions at elevated temperatures that exacerbate irreversible capacity loss. Here, a simple strategy was used to construct a dual-function Li1.5Al0.5Ge1.5P3O12 (LAGP) protective layer on the surface of the high-nickel single-crystal (SC) cathode material, leading to [email protected] material. The strong Al–O bonding effectively inhibits the release of lattice oxygen (O) at elevated temperatures, which is supported by the positive formation energy of O vacancy from first-principal calculations. Besides, theoretical calculations demonstrate that the appropriate amount of Al doping accelerates the electron and Li+ transport, and thus reduces the kinetic barriers. In addition, the LAGP protective layer alleviates the stress accumulation during cycling and effectively reduces the erosion of materials from the electrolyte decomposition at elevated temperatures. The obtained [email protected] cathode material demonstrates much enhanced cycling stability even at high voltage (4.6 V) and elevated temperature (55 °C), with a high capacity retention of 91.3% after 100 cycles. This work reports a simple dual-function coating strategy that simultaneously stabilizes the structure and interface of the single-crystal cathode material, which can be applied to design other cathode materials.