N/O co-doped litchi peel derived porous carbon materials for supercapacitors

Abstract

Biomass-derived porous carbon materials, enriched with heteroatom doping, particularly nitrogen and oxygen, have garnered significant attention as promising candidates for supercapacitor electrodes. By utilizing litchi peel, a byproduct of the widely cultivated fruit, as a precursor, we successfully synthesized a series of N/O co-doped porous carbon materials (NO-LPC-y). Notably, NO-LPC-1 exhibits a remarkable specific surface area of 996.05 m² g⁻¹ and a substantial microporosity percentage of 50.94 %. The high content of nitrogen (6.3 %) and oxygen (18.01 %) synergistically enhances the wettability and capacitance properties of the material. In a 6 M KOH three-electrode system, NO-LPC-1 demonstrated a specific capacitance of 320.0 F g⁻¹, accompanied by an impressive capacitance retention of 74.66 %. Furthermore, symmetric supercapacitors constructed with NO-LPC-1 achieved notable energy densities ranging from 8.63 (250 Wh·kg⁻¹/6 M KOH) to 15.36 Wh·kg⁻¹ (400.1 W kg⁻¹/1 M Na₂SO₄) in various electrolytes while displaying remarkable cycling stability, retaining 96.9 % of their initial capacitance after 12,000 charge/discharge cycles. This study validates the efficacy of our method in enhancing the electrochemical properties of biomass-derived porous carbon electrodes, thereby advancing the development of high-performance supercapacitors.