Multiphysics Approach to Modeling Supercapacitors for Improving Performance

Supercapacitors are a strong candidate for high-power applications such as electric/hybrid vehicles and electronic devices due to their high power densities and high efficiency particularly at low temperatures. In these applications, supercapacitors are used as energy-storage devices with capability of providing the peak-power requirement. They are subject to heavy duty cycling conditions which result in significant heat generation inside the supercapacitors. Therefore, thermal management is a key issue concerning lifetime and performance of supercapacitors. Accurate modeling of temperature field inside supercapacitors is essential for designing an appropriate cooling system, meeting the safety and reliability requirements of power systems. The objective of this paper is to study the transient and spatial temperature distribution in supercapacitors, in which a supercapacitor product with prismatic structure, based on the activated carbon and organic electrolyte technology, was chosen for modeling. A multi-dimensional thermal and electrochemical coupled model was developed by a commercial software COMSOL. In this approach, the 3D energy equation was coupled with a 1D electrochemical model via the heat generation and temperature-dependent physicochemical properties, including diffusion coefficient and ionic conductivity of electrolyte ions. Location-dependent convection and radiation boundary conditions were applied to reflect different heat dissipation phenomena of all surfaces. This model is capable of predicting electrochemical performance and temperature distribution for different involved parameters. The results of this model can also be used to determine the optimum thermal management system for various supercapacitor applications.