High surface area porous carbon derived from chitosan: CH3COOH/(NH4)2HPO4 dual-assisted hydrothermal carbonization synthesis and its application in supercapacitor

The properties of electrode materials like porous carbon are significant for energy storage devices like supercapacitors. In this work, CH3COOH/(NH4)2HPO4 dual-assisted hydrothermal carbonization (DA-HTC) is used to prepare chitosan derived porous carbon. The effects of addition sequence and ratio of the two additives on hydrochar and porous carbon were studied systematically. It is found that the DA-HTC can further improve the carbonization degree and change surface state of the hydrochar, leading to optimized KOH activation. Compared with traditional HTC or single additive assisted HTC, improved specific area (3423 m2/g) and electrochemical performance were achieved when 11 mL acetic acid and 2 g (NH4)2HPO4 were added in a stepwise manner (CPCAc1PS). In a three-electrode system, the specific capacitance of CPC-Ac1PS reached 419.6 F g-1 at 0.5 A g-1. Retention rate of 95 % was achieved after 15,000 charge and discharge cycles at10 A g-1. Herein, the results and discoveries may provide a significant example for further rational design of multi-additive assisted hydrothermal systems and better structural tuning of biomass molecules derived porous carbon.