18650高容量锂离子电池研制

Study of high-capacity 18650 Li-ion battery

采用高镍材料作为电池正极制作了18650型圆柱锂离子电池（0.5C放电标称容量为2 800mAh）,并对该材料扣式电池与18650锂离子电池性能进行了测试。结果显示：高镍材料扣式电池首次充放电效率为88.7%;Li氧化覆盖整个氧化峰范围（3.7~5.0V）,同时4.25V时Ni 2＋/Ni 4＋电对氧化,5.0V处为Co3＋/Co4＋的氧化,并且反应开始时优先发生Ni的氧化,随着电位增大,发生Co的氧化。高镍材料18650锂离子电池0.5C、1.0C、2.0C放电容量分别是0.2C时的99.89%、99.26%、97.38%,能够满足电池对于快充快放的使用要求;电池0.5C充电1C放电20周、100周、200周、450周对应容量保持率分别为98.40%、94.74%、87.62%、82.22%。低倍率（0.5C）时,常规结构18650电池与本实验结构电池的散热效果相当,随着放电倍率增大,两种结构散热效果温度差值也增大。

18650cylindrical Li-ion battery was made with nickel-rich composite material as cathode in this paper.And the battery＇s nominal capacity was 2 800 mAh at 0.5C.The performance of nickel-rich composite button cell and 18650 type full battery was tested.The testing results showed that,the first charge/discharge rate of the composite materials of cobalt/nickel/manganese was 88.7%,and Li oxidation covered the oxidation peak from 3.7Vto 5.0V,and the oxidation of Ni 2＋to Ni 4＋at 4.25 V,while Co3＋oxidized to Co4＋at 5.0V,Ni oxidation preferentially occurred at the beginning of the reaction.With the increasing of potential,the Co3＋subsequently oxidized.For the nickel-rich composite 18650 type full battery,the discharge of 0.5C,1.0C,2.0Crate contrasting to 0.2Cwas 99.89%,99.26%,97.38%,respectively.And it can meet the requirements of fast charge/discharge.The capacity retention rate of 18650 type full battery after（0.5Ccharge/1Cdischarge）20cycles,100 cycles,200cycles,475 cycles,was98.40%,94.74%,87.62%,82.22%,respectively.At low discharge rate,there was no marked difference between the traditional structure 18650 battery and the tested nickel-rich battery.And with the increasing of the discharge rate,the temperature difference of two structure battery increased.