Synthesis of LiNi_(0.8)Co_(0.2)O_2 in Air Atmosphere and its Characterization

摘要

The commercialized lithium secondary cells need the electrode materials with high specific capacity, lower pollution and lower price. Certain industrial materials (NiSO_4, CoSO_4, LiOH centre dot H_2O) were used to synthesize Ni_(0.8)Co_(0.2)( OH )_2 of a stratified structure, when various synthesis conditions such as pH, reaction temperature et al. were controlled strictly. After LiOH centre dot H_2O and Ni_(0.8)Co_(0.2)(OH)_2 were calcinated in air atmosphere, LiNi_(0.8)Co_(0.2)O_2 positive electrode materials with good layered crystal structure was obtained. Tests showed that the optimal calcination temperature in air atmosphere was about at 720 deg C and LiNi_(0.8)Co_(0.2)O_2 synthesized in the above conditions had good electrochemical properties and a low cost. The first specific discharge capacity of the material was 186 mAh/g, and the specific discharge capacity was 175 mAh/g after 50 cycles at a 0.2C rate, between 3.0 approx 4.2 V with a discharge deterioration ratio of 0.22 percent each cycle. Tests showed that LiNi_(0.8)Co_(0.2)O_2 positive electrode materials was a promising candidate to replace the commercialized LiCoO_2 for lithium secondary batteries.