Supercapacitors are a possible alternative to batteries. They charge and discharge a lot quicker, but have not reached comparable capacities yet. The energy density of a supercapacitor depends on its capacity and operating voltage. The capacity can be improved by changing the electrode materials, while stable electrolytes are needed for high operating voltages.
Guofu Ma, Ziqiang Lei, Northwest Normal University, Lanzhou, China, and colleagues have developed an asymmetric supercapacitor based on NiSe@MoSe2 nanosheet arrays and nitrogen-doped carbon nanosheets as the respective materials for the two electrodes. To synthesize the NiSe@MoSe2 nanosheets, the team combined selenium powder, hydrazine hydrate, and sodium molybdate with nickel foam using a hydrothermal process. The nitrogen-doped carbon nanosheets were prepared from the mesocarp (the white parts) of pomelo fruits. The mesocarp was treated with urea and calcium chloride in ethanol and then carbonized at 800 °C.
The team combined the two electrodes with a separator and current collectors to form a supercapacitor device, using a KOH solution as the electrolyte. The device shows a high energy density (32.6 Wh kg−1 at a power density of 415 W kg−1), as well as good cycling stability. The team attributes the good performance to the formation of ultrathin non-aggregated MoSe2 nanosheets with sufficient space for electrolyte diffusion and the porous structure and high nitrogen doping of the carbon nanosheets. According to the researchers, the electrode materials are promising for high-performance energy storage applications.
- High-Performance Asymmetric Supercapacitor Designed with a Novel NiSe@MoSe2 Nanosheet Array and Nitrogen-Doped Carbon Nanosheet,
Hui Peng, Jiezi Zhou, Kanjun Sun, Guofu Ma, Zhiguo Zhang, Enke Feng, Ziqiang Lei,
ACS Sustainable Chem. Eng. 2017.