Design of nickel-cobalt bimetallic phosphide and carbon composite from Ni-Co-PBA and polyphosphazene for high-performance asymmetric supercapacitors

Multi-component modulation and precise structure control have always been effective means to develop advanced supercapacitor electrodes. In this study, a composite of nickel‑cobalt bimetallic phosphide and carbon (PBA@PZS-700) with high surface area (121.3 m² g⁻¹) and rich porosity was facilely fabricated using Ni-Co-PBA nanocube as template by in situ polymerization of tetraethylenepentamine and N/P-rich hexachlorocyclotriphosphazene on the template surface and subsequent one-step calcination at 700 °C. The PBA@PZS-700 could act as a favorable electrode for rechargeable supercapacitor with outstanding specific capacitance (1976 F g⁻¹ or 790.4 C g⁻¹ at 1 A g⁻¹), super rate response (68.6 % retention at 20 A g⁻¹), and good cycling stability (capacitance retention rate of 70.8 % over 5000 cycles at 10 A g⁻¹). Moreover, it was combined with commercial activated carbon to construct a high-performance asymmetric supercapacitor (PBA@PZS-700//AC), which could store energy up to 51.8 Wh kg⁻¹ at the power density of 1019.08 W kg⁻¹ and has a stable longevity (over 10,000 cycles).