镍钴铝三元锂电池容量“跳水”机理研究  

Research on Capacity Plunge Mechanisms of NCA/Graphite Lithium-ion Batteries

作　　者：杨小龙[1] 罗卫 樵燊 高晓琳 YANG Xiaolong;LUO Wei;QIAO Shen;GAO Xiaolin(State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,Hunan University,Changsha 410082,China)

机构地区：[1]湖南大学汽车车身先进设计制造国家重点实验室,湖南长沙410082

出　　处：《湖南大学学报（自然科学版）》2023年第6期171-179,共9页Journal of Hunan University:Natural Sciences

基　　金：国家自然科学基金资助项目(51775179);汽车仿真与控制国家重点实验室基金项目(20201210)。

摘　　要：对一款商用镍钴铝(LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2),NCA)/石墨锂电池进行固定节点老化实验,结合差分电压分析方法和电化学阻抗谱分析方法辨识出全生命周期内的老化模式,通过观察微观形貌对老化机理进行验证.分析结果表明,该锂电池容量衰减过程存在2个阶段:第1阶段容量衰减较慢,该阶段的老化模式主要以负极活性材料损失和锂离子损失为主;第2阶段容量衰减剧烈,这是由于负极表面发生了析锂,直接消耗大量可循环锂造成锂离子损失增加,之后金属锂与电解液反应形成钝化层,增加电极在脱嵌锂过程中的机械应力,使得电极活性材料损失增加.析锂副反应造成了容量“跳水”现象,后续钝化层的形成导致的活性材料损失加剧和析锂副反应的持续发生则是老化第2阶段容量快速衰减的原因.In this study,the aging mechanism of commercial LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)/Graphite lithium-ion batteries at fixed nodes was studied experimentally,and the degradation modes in the whole life cycle were identified by differential voltage analysis method and electrochemical impedance spectroscopy analysis method,and verified by microscopic morphology observation.The results show that the capacity degradation of these lithium-ion batteries has two stages.In the first stage,the capacity degradation is slow,and the degradation modes in this stage are mainly composed of loss of anode active material and loss of lithium ions.In the second stage,the capacity degradation is sharp due to the lithium plating on the surface of the anode,which consumes a large number of recycled lithium ions directly,so the loss of lithium ions increases.The metallic lithium then reacts with the electrolyte and forms a dense covering layer,which increases the mechanical stress of the electrode in the process during the Li+intercalation/deintercalation processes,and makes the loss of electrode active material increase.Generally speaking,the lithium plating causes the capacity plunge phenomenon,the formation of the passivation layer aggravates the loss of active material,and the continuous lithium plating causes drastic capacity decay in the second stage of aging.

关 键 词：锂离子电池 衰退 石墨 容量跳水 老化机理 

分 类 号：TM912.9[电气工程—电力电子与电力传动]