Fabrication of high-energy hybrid capacitors by using carbon-sulfur composite as promising cathodes

The full realization of the high energy density concept in current hybrid capacitors is still a challenge due to the huge difference in specific capacity and reaction kinetics of the commonly used cathode and anode materials. Herein, for the first time, the carbon-sulfur composite is proposed as the high-capacity cathode for hybrid capacitors to achieve a high energy density. The as-prepared carbon-sulfur composite delivers a high specific capacity of 212.2 mAh g(-1) (424.4 F g(-1)) at 4 A g(-1), which is much higher than that of the pure carbon cathode. Additionally, the kinetics gap between cathode and anode is narrowed by using carbon-sulfur composite as the cathode. As a result, the carbon-sulfur composite based hybrid capacitor delivers a high energy density of 258.4 Wh kg(-1) at 995 W kg(-1). Even at high power density of 17350 W kg(-1), the energy density can still remain 125.3 Wh kg(-1). This study provides an alternative approach for designing hybrid capacitors with both high energy and power density by using carbon-sulfur composite as the cathode, and also paves a way to extend the application of sulfur to a new field for taking its advantages of high-capacity, environmental friendliness, low-cost.