Self-assembly preparation of mesoporous hollow nanospheric manganese dioxide and its application in zinc-air battery

Abstract

In this work, mesoporous manganese dioxide with novel hollow nanospheric structure was prepared by a facile, template-free self-assembly process at room temperature in a short period of time. The product was characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results indicate that the as-prepared material has a special mesoporous hollow nanospheric morphology and a typical composition of γ-MnO2. Polarization curve, chronoamperometry and Tafel plot tests demonstrate that this nanostructured material has high electrocatalytic activity for the reduction of dioxygen compared to commercial electrolytic MnO2 (EMD). Electrochemical impedance spectroscopy that was analyzed by equivalent circuit shows that as-prepared MnO2-catalysted air electrode has a small contact resistance and ohmic resistance, a low value of electrochemical polarization resistance. An all solid-state zinc-air cell has been fabricated with this material as electrocatalyst for oxygen electrode and potassium salt of cross-linked poly(acrylic acid) as an alkaline polymer gel electrolyte. The cell has a better discharge characteristic than that of the cell employing EMD at room temperature.