Enhanced electrochemical performance of Ni-rich cathode material by N-doped LiAlO2 surface modification for lithium-ion batteries

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LiNi0.6Co0.2Mn0.2O2 (NCM) cathodes are regarded as prospective cathodes for high-performance Lithium ion batteries due to its low costs and high energy density. Nevertheless, poor electrochemical performance severely hinders its further commercial applications. In this study, an effective surface modification strategy to fabricate N-doped LiAlO2 was coated on the surface of LiNi0.6Co0.2Mn0.2O2, and electrochemical performance are greatly enhanced. The nitrogen (N)-doped LiAlO2 (LAO) coated LiNi0.6Co0.2Mn0.2O2 not only exhibit best cycling performance with capacity retention of 87 % after 450 cycles at 1 C (210 mA g−1) under voltage range of 2.7-4.5 V, but also approaches 167 and 154 mAh g−1 at 5 C and 10 C, respectively. The N-doped LiAlO2 surface modified LiNi0.6Co0.2Mn0.2O2 not only suppresses the occurrence of surface side reaction, structural degradation and intergranular cracks, but also remove residual lithium from the LiNi0.6Co0.2Mn0.2O2 surface. Most importantly, in constructed this N-doped LiAlO2 layer, the LiAlO2 with the similar layered structure as LiNi0.6Co0.2Mn0.2O2 can tightly immobilize on the LiNi0.6Co0.2Mn0.2O2 surface, and the N-doping could induce the formation of oxygen vacancies and Al-N bond on surface of the LiAlO2 as well as enlarge interslab distance for the migrating Li+ in the LiAlO2 lattices. These finding not only promoted the commercial application of Ni-rich material, but also provided a new idea for other layered structure cathode.