Synthesis of X₃(PO₄)₂ [X = Ni, Cu, Mn] Nanomaterials as an Efficient Electrode for Energy Storage Applications

In this study, a general and effective phosphorization strategy is demonstrated to enhance the super capacitor performance of Ni, Cu, and Mn transition metals. The composites such as Ni₃(PO₄)₂, Cu₃(PO₄)₂ and Mn₃(PO₄)₂ were achieved by employing hydrothermal method mixing with ethylene glycol. These composite nanostructures were characterized by standard sophisticated techniques such as XRD, RAMAN, FTIR, UV, PL and SEM studies. X-ray diffraction (XRD) studies revealed the monoclinic crystallographic structure of the materials. The optical and vibrational properties of the product are characterized by photoluminescence and FTIR studies. These prepared materials have shown desired electrochemical stability. The above characterization indicates the functional groups and materials nature. The electrochemical properties of synthesized phosphate materials are analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charging and discharging studies (GCD). The Cu₃(PO₄)₂ electrode showed a remarkable specific capacitance of 232.025 F g^-1 at a scan rate of 20 mV/s, which is expected to have a promising electrode for super capacitor applications. The GCD study of synthesized Cu₃(PO₄)₂ nanostructure has also been tested for 1000 cycles at 10 A/g current density to evaluate the cyclic stability of the electrode and retains 94% of initial specific capacitance.