Biomass-derived B/N/P co-doped porous carbons as bifunctional materials for supercapacitors and sodium-ion batteries

Abstract

Porous carbon materials as one of the most promising electrodes for energy storage and conversion devices have attracted considerable attention because of their large specific surface area, well-developed pore structure, excellent electrical conductivity and low cost. However, the traditional production of porous carbon is often accompanied by complex synthesis conditions, environmental pollution and large energy consumption. Herein, a new type of B/N/P co-doped porous carbon (OPBNP) was prepared using a simple hydrothermal doping method combined with a low-temperature carbonization–activation process using orange peel (OP) as the precursor, and boric acid and diammonium phosphate as co-dopant. The carefully regulated elemental doping and low carbonization temperature (600 °C) endow the prepared OPBNP material with a high specific surface area (1774.8 m² g⁻¹), microporous-dominated hierarchical structure, larger graphite interlayer spacing (0.392 nm), and more defects. The combination of structurally strategic design and multi-atom doping promotes fast charging and long-lasting stability. As electrodes in supercapacitors (SCs), the OPBNP delivers a superior specific capacitance of 289 F g⁻¹ at 5 A g⁻¹ with 93.6% capacitance retention after 10 000 cycles. Besides, the assembled OPBNP//OPBNP symmetric supercapacitor could reach a high energy density of 8.9 W h kg⁻¹ at a power density of 499.7 W kg⁻¹. Furthermore, as anodes for sodium ion batteries (SIBs), OPBNP exhibits a high reversible capacity of 292.3 mA h g⁻¹ after 100 cycles at 0.1 A g⁻¹ and an excellent cycling performance of 206.6 mA h g⁻¹ after 1000 cycles at 1 A g⁻¹. The B/N/P co-doped porous carbon has the characteristics of low cost, simple preparation and excellent properties, making it a great potential electrode for advanced supercapacitors and sodium ion batteries.