Research on the thermal runaway of lithium-ion batteries based on an electrochemical-thermal-mechanical coupling model
To improve the safety performance of lithium-ion batteries and reduce safety accidents caused by thermal runaway,the causes of battery temperature rise are analyzed and their temperature is effectively reduced.According to the interaction between concentration,potential and heat,and temperature in electrochemical reactions,an accurate electrochemical-thermal-mechanical coupling model is established.Fluent was used to simulate the real-time temperature distribution of single cells and battery packs,and the influence of the proportion of heat production rates of ohmic heat,the heat of polarization,and electrochemical reaction heat on the uneven temperature distribution of single cells and normal distribution of battery pack temperature was analyzed by Fluent,and the reasons for temperature aggregation in battery packs were explored.To prevent thermal runaway in the battery pack,the position distribution of single cells in the battery pack was optimized,the influence of heat exchange area and flow rate on its heat dissipation was discussed,and the heat dissipation of different heat transfer media was compared.The research results indicate that under low and relatively high-temperature environments,the proportion of heat generated by ohmic heat,polarization heat,and electrochemical reaction heat is different,but the highest temperature of heat generation does not reach the critical temperature of 420 K for the decomposition reaction between electrode materials and electrolyte;In a high-temperature environment,the battery temperature continues to rise close to the critical temperature,leading to a trend of thermal runaway.The convective heat transfer coefficient has a significant impact on it.The temperature of the gapless battery pack is high and unevenly distributed,and the overall temperature of the battery pack with a gap of 10 mm and 20 mm is reduced by 1.1％and 1.8％respectively compared with the gap of 0,and the heat dissipation of the latter is about 1.64 times that of the former.When the gap is 10 mm,the copper plate and aluminum plate are used as the heat transfer medium,which is 2.0％and 1.6％lower than the gapless battery pack,respectively.
safety engineeringelectrochemical-thermal-mechanical couplinggap battery packconvective heat transfer coefficientthermal runaway
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