锂离子电池电极微结构的分形建模及热-化耦合  

Fractal modeling and thermal chemical coupling of electrode microstructure of lithium battery

作　　者：汪振毅 张赛[1] 胡世旺 WANG Zhenyi;ZHANG Sai;HU Shiwang(Faculty of Mechanical and Electrical Engineering,Kunming University of Science and Technology,Kunming 650500,Yunnan,China)

机构地区：[1]昆明理工大学机电工程学院,云南昆明650500

出　　处：《储能科学与技术》2022年第11期3574-3582,共9页Energy Storage Science and Technology

基　　金：昆明理工大学省级项目(KKSY201601011);云南省科技厅青年基金项目(KKSQ201701008)。

摘　　要：锂离子电池电极是决定电池性能优劣的关键因素,在多孔电极理论基础上引入分形理论,重构电极的微结构,考虑结构参数以及温度对有效扩散系数的影响,推导出锂离子在固、液相中有效扩散系数的理论模型,对其影响因素进行分析;建立热-化耦合模型,分析热模型与电化学模型之间的关系;模拟放电过程,探究不同固、液相有效扩散系数对放电性能的影响。结果表明,液相中锂离子的有效扩散系数随面积分形维数、孔隙度以及温度增大而增大,随迂曲分形维数增大而减小;固相有效扩散系数随面积分形维数增大而减小;在相对高倍率放电的情况下,改变负极颗粒粒径大小及分布,使得电极微观结构发生变化,从而使锂离子在固、液相中有效扩散系数发生变化,进一步影响了电池的最大放电容量。本工作为锂离子电池电极的制造提供了基础理论参考。The electrode of a lithium ion battery is the crucial factor in determining the performance of the battery.According to the porous electrode theory,fractal theory is introduced to reconstruct the microstructure of the electrode.The theoretical model of the effective diffusion coefficient of lithium-ion in solid and liquid phases is deduced,and its influencing factors are analyzed,taking into account the impact of structural characteristics and temperature on the effective diffusion coefficient.The relationship between the thermal and electrochemical models is established,and the thermal chemical coupling model is examined.The discharge process is simulated to explore the effects of different solid and liquid effective diffusion coefficients on the discharge performance.The results demonstrate that the effective diffusion coefficient of lithium-ion in the liquid phase increases with the increasing porosity,temperature,and area fractal dimension while decreasing with increasing tortuous fractal dimension.The solid diffusion coefficient decreases with the increase in area fractal dimension.In the case of comparatively high rate discharge,altering the particle size and distribution of the negative electrode changes the microstructure of the electrode so that the effective diffusion coefficient of lithium-ion in the solid and liquid phases changes,which further influences the maximum discharge capacity of the battery.This result provides basic theoretical knowledge for manufacturing lithium-ion battery electrodes.

关 键 词：锂离子电池 分形理论 电极微结构 有效扩散系数 颗粒粒径 

分 类 号：TM911.3[电气工程—电力电子与电力传动]