Carbonization of bacterial cellulose with structure retention and Nitrogen/Sulfur/Oxygen doping for application in supercapacitors electrode

Abstract

Bacterial cellulose (BC) presents great potential as an economical and sustainable biomass for the preparation of porous carbon electrodes for electrochemical energy storage. However, it is a challenge to maintain the natural structural advantages of BC and regulate the chemistry during the carbonization, significantly hindering the practical application. This study proposes a straightforward and efficient approach to rationally control the carbonization process of BC for improving structure retention and endowing multiple atomic doping, contributing an advanced electrode for supercapacitors. The addition of ammonium sulfate ((NH4)2SO4) is instrumental in promoting the early dehydration carbonization, forming a carbon layer with thermal insulation. This thermal barrier suppresses the volatile organic compound formation, resulting in the inhibition of volume shrinkage and boosted carbon yield. Moreover, the air activation combined with the addition of (NH4)2SO4 contributes to a Nitrogen/Sulfur/Oxygen-doped carbon electrode. The well-maintained hollow structure and diverse chemistry provide sufficient active sites and enhanced ion diffusion, resulting in a specific capacitance of 268.2 F/g at a current of 0.5 A/g and outstanding capacitance retention of 99.46 % after 10,000 cycles at 5 A/g. This work provides a deep insight into the development of cost-effective biomass in developing advanced carbon electrodes for efficient energy storage.