基于伪二维电化学-热耦合模型的锂电池热特性研究

锂电池放电过程中的产热受电池内部电化学反应和欧姆效应影响,电池产热由电池化学与动力学决定,而电池动力学依赖于电池运行条件和设计参数。锂电池的六个温度依赖性参数对锂电池的放电过程中的产热速率具有影响,包括固相活性颗粒和电解液中的锂离子扩散系数、反应速率常数、电极开路电压、电解液离子电导率、热力学因子和阳离子迁移数。基于LiFePO_4圆柱形电池建立了伪二维电化学-热耦合模型,研究电池在恒流放电过程中的产热速率,以及正极、隔膜和负极各部分的产热速率和所占比例。结果表明,总产热功率随反应热的波动而变化,其中正极电极层中反应热占比最大,负极电极层中极化产热所占比例高于正极,而隔膜中的产热主要来源自欧姆热。不同对流传热系数条件下,电池的表面温度和内部温度差都不同,因此要合理的采取电池热管理措施。

The Thermal Characteristics Based On Pseudo-two-dimensional Electrochemical-thermal Coupling Model For Lithium-ion Battery

During the discharge process, the heat generation of the lithium battery was affected by the internal electrochemical reaction and the ohmic effect of the battery. The heat generation of the battery was determined by the chemistry and dynamics of the battery, while the battery dynamics depended on the operating conditions and design parameters of the battery. The effects of six temperature-dependent parameters of lithium batteries on the heat production rate during discharge of lithium-ion batteries had been explored, including diffusion coefficients of Li or Li+ in the solid active particles and in the electrolyte, reaction rate constants, open circuit potentials (OCP) of the electrodes, electrolyte ionic conductivities, the product of the thermodynamic factor and the anion transference number. To study the heat generation rates of the battery, positive electrode, separator and negative electrode during constant current discharge, a coupled thermo-electrochemical model for a LiFePO4 cylindrical battery cell had been developed. The results reveal that the total heat generation rates vary with the fluctuation of reaction heat, in which the proportion of reaction heat in the positive electrode is the largest, the proportion of polarized heat in the negative electrode is higher than that of the positive electrode, and the heat production in the separator is mainly derived from ohmic heat. Considering the influence of different convective heat transfer coefficient conditions on the surface temperature and internal temperature.