基于高镍三元材料锂离子动力电池在循环前后的热特性分析

Thermal Characteristic Analysis of Lithium Ion Power Battery Based on High Nickel Ternary Material before and after Cycle

为明确循环后高比能Li[Ni0.7Co0.15Mn0.15]O2/graphite锂离子动力电池的温度特性及产热机制。研究了循环前后电池的倍率放电性能和温度特性,并对比分析了循环前后影响电池产热的关键因素,即可逆反应热（熵热系数）和不可逆阻抗热（过电压）的变化。结果表明：与循环前电池的放电性能相比,循环后的电池放电容量和放电电压下降,放电初期电压下降显著,倍率放电性能变差;放电过程中温度的增加明显高于循环前电池,且温度的升高主要是放电初始阶段温度的升高;对比循环前后电池表面温度分布发现,放电初期循环前电池表面温度正极较高,循环后电池表面温度负极较高,放电结束时均为中心区域温度最高;电池的温度变化源于电池的可逆反应热和不可逆阻抗热,循环前后电池的可逆反应热变化不大,循环后电池在放电过程中温度显著增加的主要原因是由于放电初始阶段不可逆阻抗热的显著增大所造成的。

In order to investigate the temperature characteristic and heat generation mechanism of Li[ Ni0.7 Co0.15 Mn0. 15 ] O2/graphite lithium ion power battery after cycle, the battery performance and temperature evolution of rate disetlarge before and after cycle was studied, and key effect factors of heat generation of battery before and after cycle were analyzed, namely reversible heat （ entropic heat coefficient） and irreversible heat （ ovetwoltage）. Results showed that the discharge capacity and discharge vohage of the battery after cycle were less than that of the battery before cycle, the discharge voltage dropped significantly in the initial stage, the discharge performance of the battery after cycle became poor, meanwhile the temperature increment was much higher than that of the battery before cycle during discharge, and the temperature increment was mainly influenced by the initial stage of temperature increment during discharge. By comparing the surface temperature distribution of the battery before and alter cycle, at the beginning of discharge, the temperature of the battery before cycle was higher nero＂ positive electrode, while that of the battery after cycle was higher near negative electrode ; at the end d discharge, the highest temperature was all in the central region of the battery before and after cycle. The temperature increment of battery originated fi＇om reversible heat and irreversible heat, the reversible heat of the battery before and after cycle changed little. The significant temperature increase of battery after cycle was mainly caused by the significant increase of irreversible heat at the initial stage of discharge.