Improvement of manganese dioxide cathode by molybdenum doping in highly acidic electrolyte

Abstract

To address the increased demand for rechargeable batteries such as Li-ion, the market must introduce an alternative to Li-ion technology. Rechargeable Zn-MnO2 battery technology is one feasible option, yet it has struggled to dominate the market due to low cathode cyclic stability and potential. To look into this problem, the characteristics of the cathode material were altered in this work through Mo-doping and modification of the resulting material morphology. KMnO4 was used as a precursor in the hydrothermal synthesis of the active material, which was produced at 120 °C for 12 or 24 h with Mo doping at varied concentrations. The phase composition and morphology of the produced samples were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Moreover, the electrochemical characteristics were determined using a galvanostat. It was found that the synthesised powders consist of α-MnO2 and δ-MnO2 crystalline phases and the phase does not change after cyclic voltammetry (CV) measurements. In addition, the distribution of doped Mo before and after CV measurements was even throughout the sample surface. Furthermore, the addition of up to 2.5 mol% Mo to MnO2 increases the specific capacity of the cathode in a highly acidic (pH = 1.5) electrolyte, in addition, improved capacity retention for faster discharge rates is observed by increasing Mo doping up to 5 mol%.