Fabrication of g-CN Nanomesh-Anchored Amorphous NiCoPO: Tuned Cycling Life and the Dynamic Behavior of a Hybrid Capacitor.

Developing a novel electrode material with better electrochemical behavior and extended cyclability is a major issue in the field of hybrid capacitors. In this work, we propose a novel strategy for the facile synthesis of nickel-cobalt pyrophosphate nanoparticles anchored on graphitic carbon nitride (NiCoPO/g-CN) via the simple solvothermal method. Field emission scanning electron microscopy and transmission electron microscopy analysis revealed the uniform anchoring of NiCoPO nanocomposite on g-CN nanosheets. Benefitting from the effect of amorphous nature and a conductive matrix of the NiCoPO/g-CN (NP3) composite, the material achieves a specific capacitance of 342 F g at a scan rate of 5 mV s. Impressively, the electrode shows long-term cycling stability with 100% capacitance retention over 5000 cycles. Employing activated carbon as an anode and as-prepared NP3 as a cathode, the assembled asymmetric hybrid cell exhibits high-energy density and exceptional cyclability (specific capacitance retention over 10 000 cycles). The outstanding electrochemical and cyclic stability is attributed to the shortest electron-ion pathway with effective interfacial interaction. The low electronic resistance of the NiCoPO/g-CN nanocomposite is revealed by varying the bias voltage variation in the electrochemical impedance spectroscopy. Our results promise better utilization of the bimetallic pyrophosphate-anchored g-CN matrix as a potential electrode for high-performance energy storage devices.