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

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 degrees 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. B/N/P co-doped biomass carbons with optimized pore structure and electrical conductivity exhibited supervisor electrochemical performance in supercapacitors and sodium-ion batteries.