储能模组失效分析及结构优化研究

Failure analysis and structure optimization of energy storage module

目前行业内通过对锂电池模组循环特性的研究,确定影响模组循环性能的主要因素是模组膨胀力。经研究,发现了储能模组循环衰减特性的失效机理,并且通过改善储能模组结构能够大幅度减小模组膨胀力的增大和延长模组的循环寿命。首先,从失效机理上准确识别因果关系和相关关系;其次,提供一种电芯间泡棉尺寸及粘接位置的确定方法,从而优化储能模组结构设计。最后,以磷酸铁锂280 Ah电芯1并8串(1P8S)储能模组为研究对象,堆叠1并8串(1P8S)常规储能模组1-1、1并8串(1P8S)优化储能模组2-1进行对比实验。通过在环境温度25℃,循环制式为阶梯充电/0.5 C (140 A)放电的条件下进行模组循环测试。结果表明,优化储能模组2-1在充电末端的平均压差降低了24%,在放电末端的平均压差降低了37.7%;优化储能模组2-1在充电末端的平均温差降低了约5℃,在放电末端的平均温差降低了约6℃。且优化储能模组2-1的容量保持率曲线亦优于常规储能模组1-1。

According to the current industry research on the cycle characteristics of lithium battery modules,it has been determined that the main factor affecting the cycle performance of energy storage modules is the module expansion force.Through this study,the failure mechanism of the cycle attenuation characteristic of the energy storage module is identified.By improving the optimal design of the module structure,the increase in module expansion force can be greatly reduced,and the cycle life of the modules can be extended.Firstly,the causal and correlational relationships are accurately identified from the failure mechanism.Subsequently,a method is proposed to determine the foam size and bonding position between cells,enabling the optimization of the structural design of energy storage modules.Finally,a 1P8S energy storage module that uses a lithium iron phosphate 280 Ah cell was selected as the research object.A conventional energy storage module 1-1 was compared with an optimized energy storage module 2-1,both using the same 1P8S stack.The module cycle test was conducted under ambient temperature conditions of 25 ℃,employing a step charge of 0.5 C(140 A) discharge.The results show that the optimized energy storage module 2-1 exhibits improved performance in pressure and temperature differences at the end of charge and discharge compared to the conventional energy storage module 1-1.Specifically,the average pressure difference at the charging and discharging ends of the optimized energy storage module 2-1 is reduced by 24% and 37.7%,respectively.The average temperature difference of the optimized energy storage module 2-1 is reduced by about 5 ℃ and 6 ℃ at the charging and discharging ends,respectively.The capacity retention curve of the optimized energy storage module 2-1 is better than that of the conventional energy storage module 1-1.