Ternary heteroatom (B, P, N) doped graphene for high-performance supercapacitors

Batteries and supercapacitors have become essential energy storage solutions, valued for their compact design, lightweight nature, and rapid energy delivery. However, traditional carbon-based supercapacitors are hindered by low energy density and limited charge storage capacity. To overcome these limitations, efforts have focused on tailoring carbon materials through heteroatom doping. In this work boron, phosphorous and nitrogen ternary codoped graphene (BPNG) samples were synthesized. FESEM, Raman and XPS analysis confirmed the morphology, structural integrity and bonding environment of the synthesized samples. The incorporation of 1.08 at%, 0.34 at% and 6.94 at% of B, P, and N, respectively for the optimized BPNG sample was confirmed by XPS analysis. This sample demonstrated outstanding properties with a specific capacitance of 450.86 F g^-1, significantly surpassing dual-doped (e.g., B, N-doped: 129.93 F g^-1 and B, P-doped: 155.65 F g^-1) and single-doped variants (B-doped: 152.5 F g^-1, P-doped: 211.6 F g^-1, N-doped: 98.25 F g^-1). The synergistic interaction among the three dopants significantly enhances the overall electrochemical performance: boron improves charge mobility, phosphorus contributes pseudocapacitive behavior, and nitrogen increases surface activity and wettability. A symmetric supercapacitor device, assembled using optimized BPNG delivered a high capacitance of 130.02 F g^-1, an energy density of 23.4 Wh kg^-1, and a power density of 692.31 W kg^-1 under standard slow charge-discharge conditions. The device also retained over 84.62% capacitance after 5000 cycles, demonstrating excellent cycling stability. The stable cycling and high energy-power outputs reveal its promising potential to be used in next-generation energy-storage technologies.