Preparation of porous carbons from waste sugar residue for high performance electric double-layer capacitor

Abstract

Waste sugar solution is harmful to the environment and abundant in organic waste, and waste sugar residue (WSR) was obtained by drying waste sugar solution. In order to efficiently solve this issue and created values, activated carbon was prepared by WSR with KOH as activation agent. Carbonization temperature, activation temperature, activation ratio and activation time were investigated, based on the effects of preparation conditions on the electrochemical performance of activated carbon. The electrode material shows superior electrochemical performance, especially when the activated carbon was prepared at the carbonization temperature of 600°C, activation temperature of 700°C, activation ratio of 3:1 (KOH:char) and activation time of 2.5h. It possesses the optimal electrochemical performance with a specific capacitance of 273.31Fg−1 and a specific surface area of 1953m2g−1. In order to determine the electrochemical stability of activated carbon electrodes, the cycle lifetime was performed at a current density of 1.5Ag−1. After 5000cycles, the capacitance retention rate of 90.1% could be obtained. Additionally, the energy density was relatively high at 1.5Ag−1 (up to 5.09Whkg−1). This study provides a value-added approach for WSR treatment and a potential feedstock for low cost-high performance activated carbons for electric double-layer capacitor.