镍钴锰三元锂离子电池不同电压下浮充失效机理及热安全研究  

Study on the failure mechanism and thermal safety of nickelcobalt-manganese ternary lithium-ion cells after float-charging at different voltages

作　　者：汤旭旭 许铤 储德韧 TANG Xuxu;XU Ting;CHU Deren(Shanghai Research Institute of Chemical Industry Co.Ltd.,2Shanghai Research Institute Chemical Industry Testing Co.Ltd.,3Laboratory for Quality Control and Technical Evaluation of Industrial Products(Cell),Ministry of Industry and Information Technology,Shanghai 200062,China)

机构地区：[1]上海化工研究院有限公司 [2]上海化工院检测有限公司 [3]工信部工业(电池)产品质量控制和技术评价实验室,上海200062

出　　处：《储能科学与技术》2024年第6期2044-2053,共10页Energy Storage Science and Technology

基　　金：上海市科委项目(23DZ2200800);上海市国资委项目(2021012)。

摘　　要：三元锂离子电池由于优异的电化学性能在储能领域得到广泛应用。本研究采用商用18650型镍钴锰酸锂/石墨体系电池作为实验对象,分别在4.2 V、4.4 V和4.6 V的电压下进行浮充实验。通过对新鲜电池及不同电压工况下浮充电池的容量测试、容量增量分析、阻抗测试以及拆解电池后电极材料的XRD、XPS和SEM表征,研究NCM电池浮充失效机理;通过新鲜电池及不同电压工况下浮充失效电池的ARC测试,研究浮充对NCM电池热安全性影响。实验结果表明,浮充电压越高,电池老化速度越快,4.6 V浮充下电池的平均容量衰减速率达1.166%/d。高电压浮充加剧了电池内部电解液与电极之间的界面反应,导致SEI膜增厚,阻抗增加;高电压浮充也导致了正极集流体的腐蚀,使得Al析出并沉积到负极,造成电池容量进一步衰减;浮充后电池自加热起始温度(T_(onset))明显降低,电池热安全性降低。本工作基于NCM电池浮充过程分析、浮充失效材料表征及热失控实验研究,将为了解浮充对锂离子电池的性能和热安全性影响提供理论依据和技术指导。Ternary lithium-ion cells,recognized for their superior electrochemical properties,are extensively utilized in the energy storage sector.This research uses commercial 18650 lithium nickel-cobalt-manganese(NCM)/graphite cells as experimental samples to explore the effects of float-charging at 4.2,4.4,and 4.6 V.We conducted a series of analyses including capacity tests,incremental capacity analysis,and impedance tests,complemented by X-ray diffractometry(XRD),X-ray photoelectron spectroscopy(XPS),and scanning electron microscopy(SEM)of electrode materials from disassembled cells.The influence of float-charging on thermal safety of NCM cells was studied through the accelerating rate calorimeter(ARC)test.Our findings indicate that higher float-charging voltages accelerate cell aging,with an average capacity loss rate of 1.166%/day at 4.6 V.Float-charging at elevated voltages intensifies the interface reactions between the electrolyte and electrode,resulting in a thicker solid electrolyte interface(SEI)film and a substantial increase in impedance.Furthermore,it induces corrosion of the positive collector,leading to aluminum precipitation and deposition at the negative electrode,which further accelerates the capacity attenuation.The onset temperature of self-heating(T_(onset))of the cells is reduced after float-charging,indicating a decrease in thermal safety.Through float charging process analysis,failure material characterization,and thermal runaway experiments,this study provides theoretical insights and technical guidance on the impacts of float-charging on the electronic and thermal safety performance of lithium-ion cells.

关 键 词：锂离子电池 浮充 热失控 失效机理 热安全性 

分 类 号：TM911.3[电气工程—电力电子与电力传动]