卷绕式超级电容器封装单元结构对其热行为影响的研究

Study on Thermal Behavior Influences of Spiral Wound Supercapacitors With Package Units Structure

超级电容器在充放电过程中产生的热效应会使其在短时间内温度迅速升高,从而影响其电气性能。影响热生成率最主要的3个因素是结构、材料和运行环境,该文中针对卷绕式超级电容器的结构特点,研究了其封装单元结构对热行为的影响。文中首先建立了超级电容器的电化学模型,通过欧姆定律、电荷守恒、质量守恒、焦耳热生成率对其运行过程进行控制和求解。而后建立了超级电容器的热模型,对其产热、散热过程进行分析。然后在以上基础上实现了电化学–热耦合。为便于研究,定义了极限循环次数的概念,即超级电容器在循环充放电过程中达到温度极限(允许最大温度)343.15K时的循环次数。最后借助有限元法,对不同封装单元结构(包括封装单元数量和单元尺寸)的超级电容器进行循环充放电瞬态求解,研究其所能承受的极限循环充放电次数,为超级电容器单体的优化设计提供了新思路。研究表明,大电流运行环境下,封装单元数量、单元尺寸对温度场的影响很小,综合考虑环境温度时其影响也很小;小电流运行环境下,封装单元数量、单元尺寸对温度场的影响较大,并且随着环境温度的升高,影响也随之增大。

Supercapacitors will generate heat effects in the process of charging and discharging, which will make temperature rise sharply in a short time, thus will affect the electrical performances. There are three main factors affecting supercapacitors＇ heat generation rate, including structure, material and operating condition. In terms of structural characteristics, the influence of the package units＇ structure on its thermal behavior was studied in the paper. An electrochemical model of supercapacitors was established and controlled by ohm＇s law, charge conservation, mass conservation and the joule heat generation rate. Then a thermal model was established, and the coupling of thermology and electrochemistry was achieved. For the convenience of research, the concept of limited cycle numbers was defined, which is the number of cycles when the supercapacitor reaches the limited temperature （allowable maximum temperature） 343.15K during charge and discharge processes in circulation. By using the finite element method, the thermal behavior of supercapacitors with different structures （including： the number of package units and the size of a cell） under cyclic charge and discharge was simulated to study the limited cycle numbers they can bear, which provides a new idea for a supercapacitor＇s optimization design. The simulation results show that the number of package units and the size of cells have little effects on the temperature field under high currents, even considering the ambient temperature. However, they have a great effect when the current is small： as the ambient temperature increases, the effect gets greater.