Influence of nitrogen and sulfur co-doped activated carbon used as electrode material in EmiFSI ionic liquid toward high-energy supercapacitors

Abstract

Porous carbon materials used as electrode materials could benefit from heteroatom co-doping to enhance their electrochemical properties. A one-step carbonization/co-doping procedure was developed to produce a nitrogen and sulfur (NS) co-doped activated carbon material from mangosteen shells (MS). Mangosteen is a tropical fruit globally well spread and cultivated in at least three continents and its shells represent an excellent porous carbon precursor. The amount of the doping agent (thiourea) was examined in relation to the morphological, structural, textural, and electrochemical performances of the material. The characterization results revealed that the 0.25 NS-doped MS AC electrode material was optimal and displayed a BET-specific surface area of 2308 m2 g−1. As measured by three-electrode configurations, this sample showed higher electrochemical performances than the non-doped MS AC with a specific capacity of 60.0 mAh g−1 at 0.5 A g−1. An increase in voltage (3.6 V) was observed in a symmetric supercapacitor using the doped material compared to the non-doped (2.8 V) in the same ionic liquid electrolyte. Further, the device demonstrated a specific capacity of 111.3 mAh g−1, a remarkable specific energy of 41.3 Wh kg−1 at 0.5 A g−1, and specific power of 7333.5 W kg−1 at 5 A g−1. These results pave the way for developing highly porous carbon materials with improved surface chemistry. The material can be used in different applications, including supercapacitors, batteries, and electrocatalysis at a reduced cost.