KOH Chemical-Activated Porous Carbon Sponges for Monolithic Supercapacitor Electrodes

Abstract

Developing monolithic electrodes with high capacitor performance remains a challenge in energy storage field. KOH is applied to chemically activated commercial melamine sponges, and it can prepare monolithic N-/O-doped carbon sponge (NOCS) electrodes. The graphitization degree, heteroatom content, and pore size distribution can be regulated by adjusting the KOH/melamine sponge mass ratio. The optimal electrode demonstrates specific capacitances of 440 F g–1 at 1.0 mV s–1 and 273 F g–1 at 0.5 A g–1, and the capacitance retention remains 85.0% after 10,000 charging–discharging cycles at 10 A g–1. The charge storage mechanism in NOCSs is systematically studied by separating the capacitive effect (pseudo-capacitance) from the diffusion-controlled contribution (electrical double-layer capacitance). Moreover, the capacitance performances of NOCSs in a polyvinyl alcohol/KOH electrolyte are also investigated by assembling all-solid-state supercapacitors, which can output an energy density of 5.61 W h kg–1 at 250 W kg–1 and power three light-emitting diodes with different colors.

Ultrahigh‐areal‐capacitance aqueous supercapacitors enabled by soft biomass‐derived porous carbon membrane

“…As the total amount of the heteroatoms in PECM electrodes decreases with pyrolysis temperature, this result indicates that the extra PC contribution is stem from the doping effect of heteroatoms within PECM electrodes. 43 This also reveals that the use of soft biomass such as PE with natural multi-heteroatoms is an effective carbon precursor to prepare heteroatom-doped carbon membrane with superior capacitive performance. Notably, the PECM-800-based SC can deliver a high energy density of 0.16 mWh cm À2 at a power density of 4.02 mW cm À2 in the potential window of 0 to 1.0 V (Figure 5H).…”

Ultrafast Porous Carbon Activation Promises High‐Energy Density Supercapacitors

“…The microporous and mesoporous structure is formed by pyrolysis of carbonates (after KOH activation) and biomass-derived porous carbons by HTS process, which generates CO, CO 2 , H 2 O, and other gases. [41,42] The molten mixture can expand and form continuous pore structure due to gas escaping. High specific surface area and narrow pore size distribution facilitate charge storage and ion transfer when APCs are used as electrode materials.…”

Development of Uniform Porous Carbons From Polycarbazole Phthalonitriles as Durable CO2 Adsorbent and Supercapacitor Electrodes

“…Moreover, GCD experiments were carried out to validate the capacitive characteristics of the investigated polymers at various current densities (1, 2, 3, 5, 10, and 20 A g −1 ), as shown in Figure 9 ( Jing et al, 2021 ). In harmony with the CV results, the polymeric electrodes displayed triangular charge–discharge plots with a small bend, demonstrating a combination of EDLC and pseudocapacitive performance induced by Faradic electrochemical redox processes.…”