Lithium nickel cobalt oxides synthesized from Li_2CO_3, NiO and Co_3O_4 by the solid-state reaction method

摘要

LiNi_(1-y)Co_yO_2 (y = 0.1, 0.3 and 0.5) are synthesized by a solid-state reaction method at 800 °C and 850 °C from Li_2CO_3, NiO and Co_3O_4 as starting materials. The electrochemical properties of the synthesized LiNi_(1-x)Co_yO_2 are investigated. The synthesized LiNi_(1-x)Co_yO_2 has an α-NaFeO_2 structure with a rhombohedral system (space group;;R3m). Among all of the prepared LiNi_(1-x)Co_yO_2 (y = 0.1, 0.3 and 0.5) samples, LiNi_(0.5)Co_(0.5)O_2 calcined at 800 °C for 40 h has the best cycling performance (capacity fading rate 1.4 mAh/g/cycle) and a relatively large first discharge capacity (147.6 mAh/g). LiNi_(0.5)Co_(0.5)O_2 calcined at 800 °C for 40 h has a large value of I_(003)/I_(104).The low degree of displacement of the nickel and lithium ions in this sample is believed to have led to its relatively large first discharge capacity and best cycling performance.