Electrochemical characteristics of LiNiO2 and LiCoO2 as a positive material for lithium secondary batteries

The discharge characteristics of lithium nickel oxides have been improved by investigating their synthesizing conditions, such as their raw materials and heat-treating conditions. Lithium hydroxide (LiOH) and nickel hydroxide (Ni(OH)2) were found to be appropriate raw materials, and 750 °C in oxygen atmosphere was the most suitable heat-treating condition. Lithium nickel oxide synthesized under these suitable conditions showed a greater discharge capacity of more than 190 mAh/g than that of lithium cobalt oxide. The existence of lithium carbonate (Li2CO3) was detected, by the Fourier-transform infrared spectroscopy method, in lithium nickel oxide heat-treated in air. This suggests that the existence of Li2CO3 adversely affected the discharge characteristics of lithium nickel oxides.