Phosphorus-Doped Carbon Composites with Rich Graphene Derived from Phenol Resin as Supercapacitor Electrode Materials with High Window Potential and Energy Density

Abstract

We reported a simple one-step way for synthesizing phosphorus-doped (P-doped) carbon composites with rich graphene (P-CCG) in this study. We prepared P-CCG in the presence of KCl molten salt at 750°C by using soluble phenolic resole and triphenylphosphine as carbon and phosphorus resources, respectively. Using x-ray photoelectron spectroscopy and elemental mapping, we detected the existence of P while the structure and morphology of P-CCG were analyzed by x-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The morphology of P-CCG displayed that where scattered porous carbons exist, the graphene sheets chiefly constituted the composites. To further inquire into the influence of P doping, the electrochemical properties of P-CCG were tested by using P-CCG as the electrode material of button-type supercapacitors whose aqueous electrolyte was 6 M KOH. The results suggested P-CCG showed great improvements such as higher specific capacitance and strengthened cycling stability after 5000 cycles, compared with undoped carbon composites. The ideal sample, P0.4-CCG, offered outstanding capacitive behavior, including a larger specific capacitance of 277 F g−1, wide voltage window of 1.6 V and, a higher energy density of 26.42 Wh kg−1.