High cell-potential and high-rate neutral aqueous supercapacitors using activated biocarbon: In situ electrochemical gas chromatography

Oil palm leaf-derived hierarchical porous carbon for "water-in-salt" based supercapacitors: the effect of anions (Cl- and TFSI-) in superconcentrated conditions

This study investigates the use of a hierarchical porous carbon electrode derived from oil palm leaves in a "water-in-salt" supercapacitor. The impact of anion identity on the electrical performance of the carbon electrode was also explored. The results show that the prepared carbon had a hierarchical porous structure with a high surface area of up to 1840 m2 g-1. When a 20 m LiTFSI electrolyte was used, the carbon electrode had a specific capacitance of 176 F g-1 with a wider potential window of about 2.6 V, whereas the use of a cheaper 20 m LiCl electrolyte showed a higher specific capacitance of 331 F g-1 due to the smaller size of the Cl- anion, which enabled inner capacitance. Therefore, the anion identity has an effect on the electrochemical performance of porous carbon, and this research contributes to the understanding of using "water-in-salt" electrolytes in carbon-based supercapacitors. The study's findings provide insights into developing low-cost, high-performance supercapacitors that can operate in a wider voltage range.

Preparation of phosphorus-doped porous carbon for high performance supercapacitors by one-step carbonization

Biomass-derived porous carbon has received increasing attention as an energy storage device due to its cost-effectiveness, ease of manufacture, environmental friendliness, and sustainability. In this work, phosphorus-doped porous carbon was prepared from biomass sawdust (carbon source) and a small amount of phosphoric acid (P-doping source and gas expanding agent) by one-step carbonization. For comparison, parallel studies without phosphate treatment were performed under the same conditions. Benefiting from the addition of phosphoric acid, the prepared carbon material has higher carbon yield, higher specific area and micropore volume. Due to the heteroatom doping of P in the carbon material, the optimized PC-900 sample not only exhibits high specific capacitances of 292 F g⁻¹ and 169.4 F g⁻¹ at current densities of 0.1 A g⁻¹ and 0.5 A g⁻¹, respectively, but also excellent cycle longevity (98.3% capacitance retention after 5000 cycles) in 1 M H₂SO₄. In addition, the supercapacitor exhibits a high energy density of 10.6 W h kg⁻¹ when the power density is 224.8 W kg⁻¹ at a discharge current density of 0.5 A g⁻¹. This work proposes a sustainable strategy to reuse waste biomass in high-performance and green supercapacitors for advanced energy storage equipment.

P-doped porous carbon can be prepared by one-step carbonization using biomass sawdust impregnated with a small amount of phosphoric acid.