Converting renewable saccharides to heteroatom doped porous carbons as supercapacitor electrodes

Abstract

Supercapacitors have a high-power throughput and large cycle life, so designing a suitable electrode material is crucial. Saccharide-derived carbons have been explored as sustainable anodes for supercapacitor applications. Mono- and polysaccharides were analyzed with pre-treatment of precursors and activation to understand the critical roles of heteroatom(s) in the precursors and the functionalized architecture in the charge storage mechanism. Acid-base synergistic pre-treatment/activation resulted in an almost 10-fold enhancement in the surface area with multifaceted pore distribution, rendering enhanced charge storage. A dual effect of heteroatom functionalization and activation of saccharide precursors resulted in a high gravimetric capacitance of 172 F/g at 1 A/g in a symmetric two-electrode configuration of chitin polysaccharide samples with a power density of 5000 W/kg at 3.5 W h/kg. It showed capacity retention of up to 100% for over 10,000 cycles. The results widen the current understanding of the electrochemical behaviour of carbons using chemically treated modifications at precursor levels. It unravels the impacts of hierarchical pore size distribution achieved by pre-treatment resulting in higher energy/power density and cycling stability.