| Lithium-ion battery plays a crucial role in the national new energy vehicle macro strategy as one of the core technologies of new energy vehicles.But thermal runaway of lithium-ion battery and other safety issues are still the key bottlenecks to constraint the development of new energy vehicles.Based on the COMSOL Multiphysics simulation and the experimental study on lithium-ion battery,a thermal model was established for the nail penetration abuse experiment of lithium-ion battery,in order to analyze the heat behavior when the thermal runaway of lithium ion battery occurs under extreme use conditions.The specific work of this paper mainly includes:(1)In order to study on the thermal behavior of lithium-ion battery when thermal runaway is triggered,abuse experiment platform of lithium-ion battery is built under the conditions of high temperature and nail penetration.The experimental results show that: Under the condition of high temperature,when the surface temperature of lithium-ion battery reaches 150℃,the temperature increases by 250.4℃,the maximum temperature of the battery is 395.4℃,the heating rate of the battery is 7.36℃/s;Under the condition of nail penetration,the local temperature rises rapidly in a short period of time near the nail,and surface temperature rise to 400℃,however the battery temperature rises slowly far away from the nail,and the temperature gradient of battery is very large;(2)According to the abuse experiments,the causes of thermal runaway and the heat generation mechanism of lithium-ion battery are studied deeply.Based on the electrochemical-thermal coupling model and combined with the Arrhenius-type equations,using lumped heat capacity,thermal runaway model is built for lithium-ion battery.The model can accurately predict the battery surface temperature distribution,and the content changes of active material.It can also calculate the heat generation when active materials decompose,and explore the thermal behavior of lithium-ion battery thermal runaway;(3)According to the thermal runaway model of lithium-ion battery,the different temperature rising rate,heat source change and the temperature distribution of lithium-ion battery are studied deeply under normal working conditions,high temperature abuse condition and nail penetration abuse condition.The results of the comparative study show that under the abuse condition,the heat generation of the battery is mainly derived from the huge energy released for the decomposition reaction of the internal active material at high temperature,resulting in the occurrence of thermal runaway of lithium battery,while the heat generation is negligible from electrochemical reversible reaction.In order to explore the thermal behavior of lithium-ion battery under different working conditions,the research work of this paper adopts the combination of experiment and simulation,and provides the theoretical basis for the practical application of lithiumion battery. |
