Activated Carbon Utilization from Corn Derivatives for High-Energy-Density Flexible Supercapacitors

Abstract

Porous activated carbons from four types of corn derivatives (husk, fiber, grain, and cob) are compared for the first time regarding their structural, morphological, and electrochemical characteristics for application as electrode materials in flexible supercapacitors. Benefiting from its hierarchical porous structure, appropriate amount of N and O functional groups, large specific surface area (1804 m 2 g –1 ), and high degree of graphitization, the activated carbon from corn grains displayed the best electrochemical performance as an electrode material for supercapacitor applications; when tested in a three-electrode configuration, it had a high specific capacitance (411 F g –1 at 1.0 A g –1 ) and an excellent rate capacity (85.7% capacitance retention at 30 A g –1 ) in an aqueous 6 M KOH electrolyte. The high specific surface area and high degree of graphitization of the activated carbon from corn grains (AC grain) played crucial roles in its excellent energy storage performance. Most importantly, the flexible supercapacitor that was assembled with slot-die coated AC grain electrodes and a hydroxyethyl cellulose (HEC)/KOH biopolymer electrolyte delivered an outstanding electrochemical performance with an energy density of 31.1 Wh kg –1 at 215 W kg –1 and ultrahigh cyclic stability (91.3% capacitance retention after 10 000 cycles at a current density of 5 A g –1 ). Also, the assembled flexible supercapacitor maintained an energy density of 20.03 Wh kg –1 even under a high power density of 28.01 kW kg –1 . These findings conclude that the porous carbon material obtained from corn grains has enormous potential as a high-performance electrode material for supercapacitors.

Optimization of Water Hyacinth Stem-Based Oxygen-Functionalized Activated Carbon for Enhanced Supercapacitors

“…Since the 0.2 numerical value is a standard value in Design-Expert 10 (File Version 10.0.7.0) software, from this validation, it is found that the model is adequate for the optimization of three operational parameters. Using the same electrolytes with 6 M KOH, similar work was done by other biomass-based AC, such as chestnut AC, 37 purple corncob AC, 38 (husk, fiber, grain, and cob), 39 Metaplexis japonica-based AC. 40 3.4.…”

Biomass Activated Carbon Composites and Their Potential in Supercapacitor Applications: Current Trends and Future Perspectives

“…Due to their huge SSA, outstanding conductivity, excellent electrochemical and mechanical durability, carbonaceous materials like carbon nanotubes and graphene are the preferred electroactive materials for EDLCs. , However, because they use fossil fuels as their primary precursors, these materials are not the best options, from a sustainability point of view. Hence, activated carbons from natural biomass sources have garnered a lot of attention in recent years, because of their abundant natural availability, low cost, nontoxic nature, and renewability, as opposed to fossil fuels. − Furthermore, biomass activated carbon possess unique features, such as tunable surface chemistry, an interconnected porous framework, and abundant functional groups, which contributes to the excellent electrical conductivity and enhanced charge storage ability. − Researcher interest is currently being drawn by a variety of biomass materials, including corn stalks, , hazelnut shells, pine cones, , orange peels, , tree bark, , and others. Biomass-activated carbon possesses significantly enhanced SSA and porosity after physical or chemical activation processes, which might make it easier for the charges to move across layers of the porous carbon structure.…”