Electrochemical characteristics of LiNi1−xCoxO2 as positive electrode materials for lithium secondary batteries

Abstract Physical properties and electrochemical behavior of LiNi 1− x Co x O 2 (0.1≤ x ≤0.9) were investigated for use as positive electrode material in lithium secondary batteries with long cycle life. LiNi 1− x Co x O 2 are characterized by an α-NaFeO 2 type structure. In a three-electrode test cell, LiNi 0.7 Co 0.3 O 2 showed a large discharge capacity of 159 Ah kg −1 , and good cycle performance, with a discharge capacity deterioration ratio of 0.73% per cycle. In a 2 Wh-class cell, LiNi 0.7 Co 0.3 O 2 exhibited a discharge capacity of 520 mAh, and good cyclability, with a discharge capacity deterioration ratio of 0.026% per cycle. LiNi 0.7 Co 0.3 O 2 is a promising positive electrode material, having the largest discharge capacity and the best cycle performance in the series of LiNi 1− x Co x O 2 compounds.