圆柱26700锂离子电池电化学及热特性

Electrochemical and thermal behavior of 26700 cylindrical lithium ion battery

本文以磷酸铁锂/石墨体系26700圆柱锂离子电池为研究对象,通过使用伪二维电化学热模型进行建模,分别模拟0.5C以及1C两种不同倍率的充电策略。结果表明:模型输出结果与电池测试结果基本吻合,且在0.5C和1C恒流充电条件下,电池绝热温升实测数据与模型模拟结果基本一致。在1C充电过程中,负极因极化产生的不可逆热为主要热源,随着充电电流增加,负极过电位同步增加;而正极因锂脱嵌产生熵变,反应为吸热过程,在充电2500~3000 s期间,吸热热功率与放热热功率持平,电池温度曲线呈现平台形态。

In this paper,the electrochemical and thermal behaviors of the LiFePO_(4)/graphite system 26700 cylindrical lithium ion battery were investigated based on pseudo-two-dimensional electrochemical-thermal coupling model.By using this model,the charging processes of LiFePO_(4)/graphite system under two charging strategies with different rates of 0.5C and 1C were simulated,respectively.The results show that the model output results are basically consistent with the battery cell test results.At the same time,under 0.5C and 1C constant current charging conditions,the measured data of the adiabatic temperature rise of the cell is basically consistent with the model simulation results.During the 1C charging process,the irreversible heat generated by the polarization of the negative electrode is the main heat source.As the charging current increases,the negative electrode overpotential increases simultaneously,while the positive electrode changes due to the entropy of lithium deintercalation,and the reaction is an endothermic reaction.In the charging period of 2500−3000 s,the endothermic heat power is the same as the exothermic heat power,and the cell temperature curve appears to be a platform shape.