MnO2/carbon material cathode for rechargeable aqueous electrolyte-based zinc-ion batteries

Abstract

This research focused on improvement of the electrical conductivity of cathode material by using the MnO2 on carbon material for the rechargeable aqueous electrolyte-based zinc-ion batteries (ZIBs). This study has been divided into two sections. delta-MnO2 with nanoflower structure supported on graphite flake (MNG) was synthesized for cathode material in first section. MNG exhibits a fast insertion/extraction of Zn2+ ions with diffusion scheme and pseudocapacitive behavior. The battery using MNG cathode exhibited a high initial discharge capacity of 235 mA h/g at 200 mA/g specific current density compared to 130 mA h/g which is displayed by the pristine delta-MnO2 cathode at the same specific current density. MNG demonstrated superior electrical conductivity compared to the pristine delta-MnO2. The results obtained pave the way for improving the electrical conductivity of MnO2 by using graphite flake support. In second section, MnO2 heterostructure on multi-walled carbon nanotubes (MNH-CNT) was synthesized for cathode material. Besides, the synthesized MNH-CNT is composed of delta-MnO2 and gamma-MnO2. ZIB using the MNH-CNT cathode delivers a high initial discharge capacity of 236 mA h/g at 400 mA/g, 108 mA h/g at 1600 mA/g and excellent cycling stability. Overall, MNG and MNH-CNT cathode were seen to exhibit superior electrochemical performance. This work presents new opportunities for improving the discharge capacity and cycling stability of aqueous ZIBs.