Enhanced Performance of Nano γ-MnO2/Mesocarbon Microbeads Composite as Electrocatalyst for Solid State Zinc-Air Cells.

Abstract

Nanostructured γ-MnO₂/MCMB (mesocarbon microbeads) composite
has been prepared as electrocatalyst for application in solid-state zincair
cell. Scan electronic microscopy and X-ray diffraction show that the
MnO₂ uniformly covers on the surface of MCMB with the typical γ-MnO₂
composition. The electrocatalytic activity of the composite for oxygen
electrode was examined by cathode polarization curve, chronoamperometry
and electrochemical impedance spectroscopy (EIS). Results indicate
that the electrocatalytic activity for oxygen reduction of the composite
is better than that of single γ-MnO₂.  All solid-state zinc-air cell fabricated
using this electrocatalyst exhibits good discharge performance.  An energy
density of 320 wh kg^-1 was obtained with a power density of 27.4 w kg^-1
at discharge current of 10 mA cm^-2. The  γ-MnO₂/MCMB composite
has potential application in zinc-air cells.