三元锂离子电池的容量跳水机理研究

Research on capacity diving mechanism of ternary lithium-ionbatteries

层状LiNi_(x)Co_(y)Mn_(z)O_(2)三元正极材料因在能量密度、生产成本和环保方面的综合优势,已成为高性能锂离子电池研究的热点。随着新能源汽车市场高速发展,三元电池装机量占比逐年升高。然而在日常使用过程中,电池会出现容量快速下降的现象,为新能源汽车带来安全隐患。为了研究引起电池发生容量跳水的机理,针对某款车用Li(Ni_(1/3)Co_(1/3)Mn_(1/3))O2三元电池,研究其加速循环老化后的电池循环特性、胀气气体分析、内部材料物相结构特征,综合得出电池容量跳水机理:电池正极颗粒破裂是导致单体电池性能衰退的主要原因,颗粒破裂后金属元素发生溶解,与电解液发生副反应,加速电解液消耗,消耗殆尽时,电池出现容量跳水。

Layered LiNi_(x)Co_(y)Mn_(z)O_(2) ternary cathode materials have attracted intensive research e ff orts for highperformance lithium-ion batteries,because of their combined advantages with respect to energy density,production cost and environmental friendliness.With the rapid development of new energy vehicle market,the proportion of installed capacity of ternary battery is increasing year by year.However,in the process of daily use,the battery capacity will decline rapidly,which will bring security risks for new energy vehicles.In order to study the mechanism of battery capacity diving,this paper studied the cycle characteristics,gas composition and phase structure characteristics of internal materials of a Li(Ni_(1/3)Co_(1/3)Mn_(1/3))O2 ternary battery after accelerated cycle aging.The breakdown of the cathode particles is the main reason that leads to the deterioration of the performance of the single cell.After the breakdown of the particles,the metal elements dissolve and react with the electrolyte to accelerate the consumption of the electrolyte.When the consumption is exhausted,the capacity of the battery capacity dives.