Graphene based Supercapacitors with Improved Specific Capacitance and Fast Charging Time at High Current Density

TL;DR

This paper demonstrates graphene-based supercapacitors with high specific capacitance, energy density, and rapid charging/discharging capabilities at high current densities, suitable for high power applications.

Contribution

It introduces a modified synthesis method for graphene that enhances porosity and electrical performance, leading to superior supercapacitor characteristics compared to existing technologies.

Findings

Discharge capacitance of 195 F/g at 2.5 A/g

Energy density of 83.4 Wh/kg achieved

Maintains 98% performance after 10,000 cycles

Abstract

Graphene is a promising material for energy storage, especially for high performance supercapacitors. For real time high power applications, it is critical to have high specific capacitance with fast charging time at high current density. Using a modified Hummer's method and tip sonication for graphene synthesis, here we show graphene-based supercapacitors with high stability and significantly-improved electrical double layer capacitance and energy density with fast charging and discharging time at a high current density, due to enhanced ionic electrolyte accessibility in deeper regions. The discharge capacitance and energy density values, 195 Fg-1 and 83.4 Whkg-1, are achieved at a current density of 2.5 Ag-1. The time required to discharge 64.18 Whkg-1 at 5 A/g is around 25 sec. At 7.5 Ag-1 current density, the cell can deliver a specific capacitance of about 137 Fg-1 and maintain 98 % of its initial value after 10,000 cycles, suggesting that the stable performance of supercapacitors at high current rates is suitable for fast charging-discharging applications. We attribute this superior performance to the highly porous nature of graphene prepared with minimum restacking due to crimple nature wrinkles and the improved current collecting method.