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.

One-Step Synthesis of Monodispersed Mesoporous Carbon Nanospheres for High-Performance Flexible Quasi-Solid-State Micro-Supercapacitors

Cost-effective synthesis of carbon nanospheres with a desirable mesoporous network for diversified energy storage applications remains a challenge. Herein, a direct templating strategy is developed to fabricate monodispersed N-doped mesoporous carbon nanospheres (NMCSs) with an average particle size of 100 nm, a pore diameter of 4 nm, and a specific area of 1093 m² g^-1 . Hexadecyl trimethyl ammonium bromide and tetraethyl orthosilicate not only play key roles in the evolution of mesopores but also guide the assembly of phenolic resins to generate carbon nanospheres. Benefiting from the high surface area and optimum mesopore structure, NMCSs deliver a large specific capacitance up to 433 F g^-1 in 1 m H₂ SO₄ . The NMCS electrodes-based symmetric sandwich supercapacitor has an output voltage of 1.4 V in polyvinyl alcohol/H₂ SO₄ gel electrolyte and delivers an energy density of 10.9 Wh kg^-1 at a power density of 14014.5 W kg^-1 . Notably, NMCSs can be directly applied through the mask-assisted casting technique by a doctor blade to fabricate micro-supercapacitors. The micro-supercapacitors exhibit excellent mechanical flexibility, long-term stability, and reliable power output.

Biomass-Derived Porous Carbon Materials for Supercapacitor

The fast consumption of fossil energy accompanied by the ever-worsening environment urge the development of a clean and novel energy storage system. As one of the most promising candidates, the supercapacitor owns unique advantages, and numerous electrodes materials have been exploited. Hence, biomass-derived porous carbon materials (BDPCs), at low cost, abundant and sustainable, with adjustable dimension, superb electrical conductivity, satisfactory specific surface area (SSA) and superior electrochemical stability have been attracting intense attention and highly trusted to be a capable candidate for supercapacitors. This review will highlight the recent lab-scale methods for preparing BDPCs, and analyze their effects on BDPCs' microstructure, electrical conductivity, chemical composition and electrochemical properties. Future research trends in this field also will be provided.

Hydrophilic “bridge” tannins for stabilizing the metal selenides onto activated carbon for binder-free and ultralong-life asymmetric supercapacitors

Tannin-doped activated carbon by employing tannin as the structure coupling bridge between the two components could effectively tune the electronic structural states and result in strong coupling effects with NiCo₂Se₄.