Porous NiCoP@P–C hybrid as efficient positive electrodes for high-performance supercapacitors

Abstract Electrode materials with excellent capacitance performance remain on urgent need for energy storage devices. In this study, we successfully fabricated porous P-doped carbon-supported NiCoP nanoparticles (NiCoP@P–C) by chelating sodium alginate with Ni2+ and Co2+ ions and subsequently performing a high-temperature calcination process. The carbonization process involved phosphating the metal ions to form bimetallic NiCoP nanoparticles and doping the P element into the carbon framework. The as-prepared material integrated the merits of metal phosphide (high theoretical specific capacitance), bimetal (excellent electrochemical conductivity), and porous structure (rapid ion transportation). The sample consequently exhibited outstanding electrochemical properties with an ultrahigh specific capacitance of 920 F g−1 (0.5 A g−1) and a high cycle stability of 84% over 5000 cycles with a small mass loading of 3.6 mg cm−2. Moreover, an asymmetric supercapacitor assembled with NiCoP@P–C-500 as the positive electrode and activated carbon as the negative electrode delivered a maximum energy density of 57.8 W h kg−1 at a power density of 522 W kg−1.