B/N-Codoped Porous Carbons as Metal-Free and Binder-Free Electrode Material for Supercapacitors

A facile, cost-effective, and eco-friendly approach for the synthesis of B/N-codoped porous carbon materials has been developed for metal-free and binder-free supercapacitors. A set of samples, CPFD-B/N-5, CPFD-B/N-10, and CPFD-B/N-15 have been synthesized by carbonization of a phloroglucinol-formaldehyde-dopamine (PFD) polymer and tetraethyl orthosilicate (TEOS). Boric acid has been used to introduce different amounts of boron and an undoped sample, CPFD-N, has been synthesized for comparison. The CPFD materials function as binder-free electrodes and display excellent electrochemical behavior. The optimization of boron as a heteroatom with a rational distribution of pores enables CPFD-B/N-10 electrode to achieve a high capacitance of 962 F/g at a current density of 1 A/g in 1 M H₂SO₄ electrolyte. It demonstrates excellent rate capability and exceptional cycling stability, retaining over 120% of its capacitance after 5000 cycles at a current density of 30 A/g. It has a specific energy density of 108.22 Wh/kg and a power output of 450.00 W/kg at 1 A/g, effectively bridging the gap between supercapacitors and batteries. A solid-state symmetric supercapacitor made from the material achieves a capacitance of 622 F/g at a current density of 1 A/g, Coulombic efficiency of 89% after 1,500 cycles and powers a 3 V LED bulb.