One-step carbonization of poly(styrene/divinylbenzene) to fabricate N-doped porous carbon for high-performance supercapacitor electrode

Abstract

A one-step carbonization strategy without KOH activation has been developed to fabricate N-doped porous carbon with a large specific surface area of 1520 m² g⁻¹, a relatively high nitrogen content of 6.13 wt%, abundant active sites, partial graphitization, and high conductivity. This exploration is based on poly(styrene/divinylbenzene) (p(St/DVB) foam prepared by high internal phase emulsion (HIPE) and with the loading of urea as the nitrogen source. The carbonization process was subsequently carried out at 800 °C to achieve the synthesis of N-doped porous carbon. The electrochemical properties of N-doped porous carbon were evaluated in 0.5 M H₂SO₄ and 1 M KOH aqueous electrolytes, respectively. In acidic medium, the obtained sample exhibits a high specific capacitance of 276 F g⁻¹ at 1 A g⁻¹ in the potential range of 0–1 V and 70.2% capacitance retention at 20 A g⁻¹. Quite high stability with only 2.2% capacitance loss is confirmed through a 10,000-GCD-cycle at 10 A g⁻¹. In contrast, in a base electrolyte, the N-doped porous carbon also shows excellent energy storage performance with a specific capacitance of 268 F g⁻¹ at 1 A g⁻¹ in the potential range of – 1 to 0 V along with capacitance retention of 67.2% at 20 A g⁻¹. After 10,000 cycles tested at 10 A g^–1, our sample still maintains 94.4% retention of initial capacitance. It is convinced that the microstructures result in excellent electrochemical performance.