Polypyrrole-Modified NH₄NiPO₄·H₂O Nanoplate Arrays on Ni Foam for Efficient Electrode in Electrochemical Capacitors

The growth of active materials on Ni foam was proved to be an effective strategy to enhance redox reactions for electrochemical capacitors. But for NH₄NiPO₄·H₂O materials, a uniform nanostructure on Ni foam has not been achieved. Here, the NH₄NiPO₄·H₂O nanoplate arrays on Ni foam are fabricated by a facile solvothermal method. To further promote the transitions of current carries and benefit the electrochemical reactions, the surfaces of NH₄NiPO₄·H₂O nanoplate arrays were modified by a thin layer of polypyrrole through an in situ chemical polymerization method. The polypyrrole-modified NH₄NiPO₄·H₂O nanoplate arrays on Ni foam showed much enhanced specific capacitance in comparison with the bare NH₄NiPO₄·H₂O nanoplate arrays. When employing polypyrrole-modified NH₄NiPO₄·H₂O/Ni foam as a positive electrode and activated carbon as a negative electrode to assemble the asymmetric supercapacitor cells, favorable capacitance and cycling ability were achieved. Such a fabrication provides a feasible method to construct efficient electrodes for sustainable electrochemical energy storage.