Improving the Electrochemical Performance of Pouch Cell Electric Double‐Layer Capacitors by Integrating Graphene Nanoplates into Activated Carbon

Abstract

Herein, activated carbon (AC) is composited with multiple weight ratios of graphene nanoplates through a facile and scalable technique, including sonicating and vacuum mixing in a slurry to fabricate pouch cell electric double‐layer capacitors (EDLCs). Among the fabricated devices, the EDLC made of 2 wt% graphene/AC composite demonstrated the best electrochemical performance by enhancing the specific capacitance of AC EDLC from 27.3 to 39.3 F g −1 at 0.05 A g −1 current density. Moreover, the addition of graphene to AC leads to a more ideal capacitive behavior, reduction of charge transfer resistance ( R ct ) of the AC EDLC from 2.04 Ω to below 0.05 Ω, and the decrease of the ohmic drop at a current density of 2 A g −1 from 18.7% to 5.7%. 2 wt% graphene was considered as the optimum amount to be added to AC to increase the specific capacitance on average by 40% and improve the capacitance retention to 97% after 1000 cycles at 1 A g −1 . Furthermore, the fabricated EDLC based on the optimum ratio of graphene to AC possessed satisfactory energy densities of 13.7 and 8.3 Wh kg −1 at 50 and 2000 W kg −1 power densities, respectively.