Cycle performance of LiCoxNi1−xO2/graphite–coke hybrid carbon systems for long-life lithium secondary batteries

In our previous work, we found that the LiCoO2/graphite–coke hybrid carbon system had less initial discharge capacity but better cycle performance than the LiCoO2/pure graphite system, which is the most commonly used lithium secondary battery system. In this report, we examine the effects of a better graphite–coke hybrid carbon mixing ratio for long-life use. We have found that the feature of the curve of the carbon negative electrode material influences the feature of the discharge curve of the battery, and graphite–coke hybrid carbons with a mixing ratio of 4/1 enable better cycle performance. We compared the initial discharge characteristics and cycle performance of batteries with LiCoxNi1−xO2/graphite–coke hybrid carbon systems with those of a LiCoxNi1−xO2/pure graphite system for x = 0.3 and 0.7. Moreover, we examined the cycle performance of 10-Wh class cells using some of these systems under load-levelling imitation conditions.