Influence of precursor phase on the structure and electrochemical properties of Li(Ni0.6Mn0.2Co0.2)O2 cathode materials

LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode materials are prepared via sintering the mixtures of (Ni0.6Mn0.2Co0.2)(OH)2 precursor and LiOH. The effects of the β-(Ni0.6Mn0.2Co0.2)(OH)2 content in hydroxide precursor on the structure and electrochemical performance of NCM622 cathode materials are investigated. Among three kinds of cathodes, the cathode material sintered from β-(Ni0.6Mn0.2Co0.2)(OH)2 phase precursor exhibits the excellent layered structure with the highest c/a value. Furthermore, it displays the excellent hexagonal ordering with the lowest ratio of I(006+102)/I(101). With increasing the β-(Ni0.6Mn0.2Co0.2)(OH)2 phase content in precursors, the discharge capacity of NCM622 samples first increases, and then decreases. The cathode material sintered from the mixed phase of α-(Ni0.6Mn0.2Co0.2)(OH)2 and β-(Ni0.6Mn0.2Co0.2)(OH)2 shows the highest discharge capacity of 192.1mAh/g and best rate performance, and then is the best recommendation for a high-power cathode. While the cathode material sintered from single β-(Ni0.6Mn0.2Co0.2)(OH)2 phase shows the best cycle stability and the capacity retention of 91.7% after 100 cycles, and then is the best recommendation for a long-life cathode.