Electrochemical double layer capacitor electro-thermal modelling

Abstract

Highlights An electro-thermal model is created which is valid from (-)40 → (+)60℃  A peudo-3D thermal model is developed to determine spatial temperature variation  Electrical equivalent circuit model retains physical meaning  Differing rates of heat generation are defined for the individual cell constituents  The temperature gradient between the core of the cell and surface is defined AbstractAn electro-thermal model is generated to predict the internal temperature of an Electrochemical Double-Layer Capacitor (EDLC) undergoing high current charging/discharging. The model is capable of predicting the electrical and thermal behaviour of a cell over a wide range of operating conditions. Spiral symmetry is used to reduce the heat generation and transfer model from 3D to a pseudo-3D, which runs faster without losing fidelity. Unlike existing models, each element in the developed model retains physical meaning and the electrical model is coupled with a high-fidelity thermal model including material geometries, thermal properties and air gaps. Unequal entropy is calculated using first principles, included in the model and compared to experimental data, and shown to be valid. More entropic heat is generated at the positive electrode than the negative in a typical EDLC, and there is little spatial variation of heat generation rate within the jelly-roll. The heat-transfer model predicts temperature variations within a cell; this study examines these variations for multiple conditions. Whilst undergoing high current charging (2 seconds, 400A, 650F cell), a temperature gradient in excess of 3.5℃ can be generated between the positive terminal and the jelly-roll. The time dependent spatial temperature distribution within a cell is explored.

Experimental analysis of Hybridised Energy Storage Systems for automotive applications

“…The HESS shows a weaker dependence upon temperature, with the system using I3kF capacitors exhibiting a usable SoC range that is 36% smaller by capacity at 10℃ than at 40℃. At lower temperatures battery resistance increases significantly, whereas the SC resistance remains relatively constant, [60]. Consequently, the ratio of the relative resistance of the battery to the SCs increases, leading to a reduction of the battery current contribution to system current.…”

“…Additionally, given the smaller ratio of SC to battery cells, each SC cell will operate at a higher voltage for the SC bank and battery module voltage to match. The consequence of the SCs operating at a higher voltage is that they will exhibit a higher capacitance, as capacitance is a strong function of operating voltage, [60]. Therefore, smaller capacity SC cells are required in a module than in a lab scale test.…”

A General Parameter Identification Procedure Used for the Comparative Study of Supercapacitors Models

“…Electrochemical models consist of a set of partial differential-algebraic equations with many parameters. The estimation of the electrochemical model is very accurate [10]. However, the simulation of these models consumes many resources.…”

Online supercapacitor health monitoring using a balancing circuit

“…Due to their high energy and power density, supercapacitors [1], also known as ultracapacitors [2], or electrochemical double-layer capacitors (EDLC) [3][4] [5], are nowadays becoming a popular new generation of storage systems for high-power applications [6] [7].…”