Scaling laws for heat generation and temperature oscillations in EDLCs under galvanostatic cycling

Abstract

This study provides a framework for developing design rules and thermal management strategies for electric double layer capacitors (EDLCs). First, it presents a scaling analysis of a physical model previously derived from first principles for coupled electrodiffusion and thermal transport in electric double layer capacitors. The model rigorously accounts for irreversible (Joule heating) and reversible heat generation rates arising from electric double layer formation in binary and symmetric electrolytes. Scaling simplified the problem from twelve independent design parameters to seven meaningful dimensionless similarity parameters governing the spatiotemporal evolution of the electric potential, ion concentrations, heat generation rates, and temperature in the electrolyte. Then, similarity behavior was observed and scaling laws were developed for the total irreversible and reversible heat generated during a charging step and for the maximum temperature oscillations in EDLCs under galvanostatic cycling of planar electrodes using detailed numerical simulations.