Operando Temperature Dynamic Investigation of Electric Double‐Layer Capacitors Containing Organic Electrolytes

Abstract Variations in temperature play a substantial role in influencing the electrochemical performance of electric double‐layer capacitors (EDLCs). Lower temperatures limit the charge carriers′ transport properties, diminishing overall cell performance, while higher temperatures enhance transport properties and performance at the expense of material decomposition. Thus, investigating the temperature‐dependent behavior of supercapacitors requires numerous time‐consuming experiments while maintaining specific and consistent testing conditions. Therefore, we present a fast screening technique, named operando temperature dynamic measurements, to investigate EDLC performance under varying temperatures and voltages. The swift nature of this technique minimizes cell aging, allowing the evaluation even at harsh conditions. Utilizing temperature dynamic measurements, EDLCs containing six different organic electrolytes have been compared. Incrementally increasing temperature and cell voltage while performing electrochemical impedance spectroscopy or galvanostatic charge‐discharge measurements, metrics such as capacitance, energy, power, entropy, and enthalpy were determined. Interestingly, different performance evolutions over the temperature range are observed, allowing the identification of optimal operational conditions for each device.