Molten salt induces starch-based carbon aerogels with microsurface wrinkles for high-performance supercapacitors

Abstract

Biomass carbon aerogels are widely used as electrode materials for supercapacitors due to high specific surface area, excellent conductivity, low cost, and environmental friendliness. However, the electrochemical performance of biomass carbon aerogels decrease significantly at high power. Herein, starch-based carbon aerogels with microsurface wrinkles are designed in this study. Starch hydrogels are rapidly prepared by using the property that KOH/KCl can gelatinize starch at room temperature. During high-temperature carbonization, the molten salt that is formed by KOH and KCl gives the starch-based aerogels (KCA-KCl) a porous structures with a high specific surface area (2014 m²/g) and microsurface wrinkles. The porous structures and the microsurface wrinkles enables the material to maintain good electrochemical performance at both low and high power. When it is used as electrode material for supercapacitors, the specific capacitance of KCA-KCl is 246.0 F/g at a current density of 1.0 A/g and the capacitance retention of 10 A/g for KCA-KCl is 77.9 % in three electrode system. In two electrode system, KCA-KCl exhibited an energy density of 14.72 Wh/kg at a power density of 0.5 kW/kg and the specific capacitance can maintain 96.33 % after 10,000 cycles. This study provides a feasible strategy to prepare high-performance electrode materials for supercapacitors.