N/O co-doped porous carbon synthesized by lewis acid salt activation for high rate performance supercapacitor

Abstract

Cellulose derivatives are widely used as carbon precursors for porous carbon materials because of their high carbon contents and low cost. Herein, N/O co-doped porous carbon materials were synthesized from sodium carboxymethyl cellulose by one-step carbonization and activation with zinc nitrate hexahydrate, a lewis acid salt, as the chemical foaming agent and activation agent and urea as the nitrogen source. The nitrogen content and oxygen content of the optimized sample reached 7.6 at.% and 12.7 at.%, respectively, and the specific surface area reached 1318 m2 g−1. The doping of nitrogen element increased the specific capacitance by nearly two times. In a three-electrode system, the maximum specific capacitance reached 234 F g−1 at 0.1 A g−1 in 6 M KOH electrolyte. The maximum energy density of symmetric supercapacitor was 15.7 Wh kg−1 at the power density of 497.3 W kg−1. The capacitance retention maintained 90.3 % after 10,000 cycles at 20 A g−1. This work provides a novel method for the preparation of porous carbon materials derived from sodium carboxymethyl cellulose and expands its application in energy storage devices.