Fabrication of binder-free nickel-manganese phosphate battery-type electrode by microwave-assisted hydrothermal technique

A high-performing electrochemical binder-free nickel-manganese phosphate (NMP) battery-type electrode was successfully fabricated by the microwave-assisted hydrothermal method. The NMP was directly deposited on the nickel foam surface without a binder. Design of Experiment (DoE) was used to optimize the synthesis parameters for the NMP electrode that achieved the highest specific capacity at 90 °C, synthesis duration of 5 min, and Ni:Mn precursor ratio of 1:3. A percentage error of less than 10 % between the predicted and experimental specific capacity values was obtained, declaring that the obtained specific capacity of the optimized NMP (Ni-Mn3-P) binder-free electrode was in the 90 % confidence interval. Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy (EDX), X-Ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were utilized to determine the morphology, elemental composition, chemical state, chemical bonding, and crystallinity of the Ni-Mn3-P electrode, respectively. Based on the galvanostatic charge-discharge (GCD) analysis, the Ni-Mn3-P binder-free electrode had a higher specific capacity of 1500.0 C/g at 3 A/g current density compared to single metal phosphate electrodes (Ni-P and Mn-P). Moreover, the Ni-Mn3-P electrode also exhibited the highest capacity retention and lowest charge transfer resistance. These results suggest that the binder-free Ni-Mn3-P electrode is a potential candidate for energy storage devices.