Characteristics and electrochemical performance of cathode material Co-coated LiNiO_2 for Li-ion batteries

摘要

Spherical Ni(OH)_2 powder coated with Co(OH)_2 as raw material was mixed with LiOH to synthesize cathode material for lithium ion battery by using solid-state reaction. After sintered at temperature above 600 deg C, a solid solution with layer structure was formed. The result of XPS shows that it is a concentration gradient material with higher cobalt content at the surface, and the gradient decreases with increasing sintering temperature from 650 to 750 deg C. This new gradient material, called as Co-coated LiMO_2, exhibits excellent electrochemical performances for the cathode of Li-ion batteries in comparison with LiNiO_2 and Co-doping LiNiO_2. The discharge capacity of Co-coated LiNiO_2 is over 180 mA centre dot h/g and capacity decay per cycle is less than 0.07 percent when Co-coated LiNiO_2 consisting of 92 percent nickel and 8 percent cobalt was sintered at the temperatures between 650-670 deg C. Though initial discharge capacity could be increased with higher sintering temperature, the cycle life would be reduced.