Study of solid alkaline electrolyte under high temperatures and its application in electrochemical capacitors for AC line-filtering

Abstract

Abstract An ultra-high rate solid-state electrochemical capacitor (EC) is studied for 60\u202fHz AC line-filtering applications. The combination of vertically-oriented graphene nanosheet electrodes and a hydroxide ion-conducting tetraethylammonium hydroxide-polyacrylamide polymer electrolyte enabled an interdigitated planar EC with capacitive behaviour at rates up to 1000\u202fV\u202fs−1 and a response time of less than 1\u202fms. This performance level was maintained for over 3 weeks without capacitor packaging. The EC responded capacitively at 120\u202fHz\u202fat a temperature of 120\u202f°C, demonstrating outstanding high-temperature resiliency. Thermal and chemical characterizations of the polymer electrolyte revealed that electrochemical changes caused by high-temperature are reversible. Two competing factors were identified that govern solid-state capacitor performance at elevated temperatures.