Isothermal calorimeter for measurements of time-dependent heat generation rate in individual supercapacitor electrodes

Researchers used gSKIN® Heat Flux Sensors to measure the time-dependent heat generation rate in individual carbon electrode electric double layer capacitors (EDLC) under various conditions. They designed, fabricated, and validated a calorimeter with two gSKIN® connected to a data acquisition system, two identical and cold plates fed with a circulating coolant, and an electrochemical test section connected to a potentiostat/galvanostat system. The results of this study can be used to validate existing thermal models, to develop thermal management strategies, and to gain insight into physicochemical phenomena taking place during operation.

The research has been published in the Journal of Power Sources.

Isothermal calorimeter for measurements of time-dependent heat generation rate in individual supercapacitor electrodes

Authors: Obaidallah Munteshari, Jonathan Lau, Atindra Krishnan, Bruce Dunn, Laurent Pilon

Journal of Power Sources, Vol. 374, 15 January 2018, Pages 257–268, https://doi.org/10.1016/j.jpowsour.2017.11.012

Abstract: Heat generation in electric double layer capacitors (EDLCs) may lead to temperature rise and reduce their lifetime and performance. This study aims to measure the time-dependent heat generation rate in individual carbon electrode of EDLCs under various charging conditions. First, the design, fabrication, and validation of an isothermal calorimeter are presented. The calorimeter consisted of two thermoelectric heat flux sensors connected to a data acquisition system, two identical and cold plates fed with a circulating coolant, and an electrochemical test section connected to a potentiostat/galvanostat system. The EDLC cells consisted of two identical activated carbon electrodes and a separator immersed in an electrolyte. Measurements were performed on three cells with different electrolytes under galvanostatic cycling for different current density and polarity. The measured time-averaged irreversible heat generation rate was in excellent agreement with predictions for Joule heating. The reversible heat generation rate in the positive electrode was exothermic during charging and endothermic during discharging. By contrast, the negative electrode featured both exothermic and endothermic heat generation during both charging and discharging. The results of this study can be used to validate existing thermal models, to develop thermal management strategies, and to gain insight into physicochemical phenomena taking place during operation.

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