动力电池老化诱发热失控机理仿真

Simulation study on the mechanism and process of thermal runaway induced by aging of lithium-ion batteries

近年来,新能源汽车热失控燃烧起火的事故屡见报道,既危及消费者的生命财产安全,又影响了大众对电动汽车的信任与接受度,给新能源汽车市场的推广普及造成严重阻碍。为了从根本上为热失控防治提供有效指导,本文首先依托电池的传热传质,建立了电化学-老化-热失控-热耦合模型。接着,利用有限元软件以三元锂软包电池为对象建立了仿真模型并进行了初步验证。最后,针对以循环次数为表征的电池老化致内短路热失控问题,本文在深入其机理研究的同时,建立仿真模型探究了不同老化程度对电池温升的影响,并设计了“到达副反应阈值温度的快慢”这一无量纲风险指数β,得出了热失控发生的临界风险指数,有助于日常使用过程中热失控的预测与防治。

Recently,the thermal runaway combustion of new energy vehicles has been reported frequently,which not only endangers the safety of consumers’lives and property but also affects the public’s trust and acceptance of electric vehicles,causing severe obstacles to the promotion and popularization of the new energy vehicle market.This study first established an electrochemical-aging-thermal runaway-thermal coupling model based on the heat and mass transfer of the battery to fundamentally provide effective guidance for the prevention and control of thermal runaway.Then,the finite element software was used to establish a simulation model for the ternary lithium soft-packed battery and conduct a preliminary verification.Finally,aiming at the thermal runaway problem of internal short circuits caused by battery aging characterized by cycle times,this paper establishes a simulation model to explore the influence of different aging degrees on the temperature rise of the battery and designs the dimensionless risk index β of“the speed of reaching the threshold temperature of the side reaction”and obtains the critical risk index of thermal runaway,which is helpful for the prediction and prevention of thermal runaway in daily use.