铁磁杂质对锂离子电池自放电和电化学性能的影响

Effect of iron impurity on self-discharge and electrochemical properties of lithium ion batteries

锂离子电池自放电反应不可避免,其存在不仅导致电池本身容量的减少,还严重影响电池的配组及循环寿命。影响自放电的因素有微粉,毛刺,磁性异物等,其中以磁性金属杂质影响最大。本文通过添加不同量的纳米铁微粉,研究对三元正极材料的影响。实验结果表明,55℃高温存储7天后,磁性杂质含量为100 ppm的正极材料制成的电池,自放电率为添加量为50 ppm铁微粉的正极材料制成的电池的2倍。单质铁等磁性杂质会提高成品电池的自放电率。循环实验结果表明纯净的三元正极材料(磁性物质<100 ppb)在1 C下循环450周后,剩余容量保持在97%,比含铁杂质的好。

Self-discharge reaction of lithium-ion battery is inevitable,it leads to the reduction of the capacity,but also seriously affects the cycle life.The factors that affected self-discharge reaction are micro powder,burr,magnetic materials and so on.Among them,the magnetic metal impurity has the greatest influence.In this paper,the effect of adding different amounts of nano-iron powder on cathode materials was studied.After stored at 55℃for 7 days,the self-discharge rate of the battery with 100 ppm of magnetic impurity is twice that of the battery with 50 ppm of iron powder.Magnetic impurities can increase the self-discharge rate of the battery.Cycling experiments showed that the residual capacity of pure cathode material(magnetic material<100 ppb)remained at 97%after 450 cycling at 1 C,which was better than others.