锂离子电池电极安全添加剂

Safety-enhancing electrode additives for Li-ion batteries

分别以α-Al_2O_3和Li_2TiO_3作为锂离子电池正极和负极中的安全添加剂,提出了安全添加剂的作用模型,系统比较了有无安全添加剂的两组电池的电化学性能和安全性能。电化学性能测试结果表明,安全添加剂的加入会很小幅度降低锂离子电池的能量密度;电池的倍率性能不受影响,其在5 C放电倍率时容量保持率达到82.3%(以1 C为基准);电池的预期循环寿命达2409次(按照80%DOD计算),相比对比组电池的896次预算寿命大幅增加。安全性能测试结果表明,添加了安全添加剂的电池能够通过严苛的穿刺测试、重物撞击测试和外短路测试等安全测试,安全添加剂的存在可以有效避免电池内部局部热点的产生,使不可控的内部短路转变为可控的低倍率放电,显著提高电池的安全性能,在商业化方面展示出良好的应用前景。

Using α-Al_2O_3 and Li_2TiO_3 as safety additives in the positive and negative electrodes of Li-ion battery respectively,a mechanism model of safety additives has been proposed,and the effects of these two additives on the electrochemical performances and safety performances were investigated systematically.The electrochemical performance test results showed that energy density of Li-ion battery will reduce slightly as a result of safety additive;meanwhile,the rate performance is not affected.82.3% capacity retention at 5C discharge rateis obtained and the battery’s cycle life is expected to reach 2409 times（calculated as 80% DOD）compared with 896 times of the control battery.The safety performance test results showed that the battery with electrode safety additives could pass strict safety tests such as punch test,shock test and external short circuit test.The presence of safety additives could avoid the occurrence of local hot spots inside the battery effectively and turn the uncontrollable internal short circuit into controllable low rate discharge,which improves the battery’s safety significantly,demonstrating a good application prospects in commercialization.