Nitrogen-doped carbons derived from cotton pulp for improved supercapacitors

Supercapacitors have a rapid charge/discharge rate, long lifespan, high stability, and relatively acceptable cost, showing great potential in energy storage and conversion applications. However, the current cost-effective carbon-based electrodes have limited application owing to their low specific capacitance and unsatisfactory stability. In this regard, we herein prepare nitrogen-doped carbons by carbonizing a mixture of cotton pulp (CCP) and melamine to improve the specific capacitance by integrating pore (mesopore) and surface (oxygen-containing groups) modification with defect engineering via the carbonization process. Furthermore, the structural and morphological features of the resultant nitrogen-doped carbons are confirmed by various characterization techniques. Excitingly, the specific capacitance for nitrogen-doped CCP (CCPN1) with a 1 : 1 weight ratio of CCP and melamine is 642 F g^-1 at a current density of 0.5 A g^-1 in a three-electrode system, surpassing that of the reported carbon analogues and most metal-based materials to date. The stability test suggests that the specific capacitance of CCPN1 is maintained over 150 F g^-1 at a current density of 2 A g^-1 even over 5000 cycles. Therefore, the reported nitrogen-doped carbons from cotton pulp exhibit improved specific capacitance and stability, providing a new cost-effective carbon-based material for application in the energy storage field.

Nickel-cobalt layered double hydroxide nanosheets anchored to the inner wall of wood carbon tracheids by nitrogen-doped atoms for high-performance supercapacitors

In this paper, a novel type of electrode material for high-performance hybrid supercapacitors is designed. The electrode mainly uses nitrogen-doped atoms to anchor the nickel-cobalt layered double hydroxide on the inner wall of wood-derived carbon tracheids from Chinese fir wood scraps. The specific capacity of the composite single electrode is 14.26 mAh cm^-2 at 10 mA cm^-2. The hybrid supercapacitor with a composite electrode cathode and nitrogen-doped wood-derived monolithic carbon materials as the anode has a high specific capacitance of 4.74F cm^-2 at 5 mA cm^-2, and the capacitance retention rate is 93.15% after 8000 charge-discharge cycles. The highest energy density and power density reach 1.48 mWh cm^-2 and 22.40 mW cm^-2, respectively. After doping with nitrogen, the combination with the nickel-cobalt layered double hydroxide is more uniform and stable, and the capacitance and cycling stability are significantly improved.

Konjac glucomannan-derived nitrogen-containing layered microporous carbon for high-performance supercapacitors

Biomass-derived carbon-based materials represent a promising class of candidates for supercapacitors.