Polypyrrole-Coated Manganese Dioxide Nanowires and Multi-Walled Carbon Nanotubes as High-Performance Electrodes for Zinc-Ion Batteries

Abstract

Free-standing films based on MnO2@multi-walled carbon nanotubes (MWCNTs)@Polypyrrole (PPy) have been fabricated for aqueous zinc-ion batteries. A simple hydrothermal method was adopted to synthesize ß-MnO2 nanowires. PPy coated the ß-MnO2 nanowires@MWCNTs composite by an in-situ polymerization process. Free-standing films of ß-MnO2@MWCNTs@PPy composite were prepared by a convenient vacuum-assisted filtration. A zinc-ion battery is fabricated with a zinc foil anode and a ß-MnO2@MWCNTs@PPy composite cathode. The Zn//ß-MnO2@ MWCNTs@PPy system in ZnSO4@MnSO4 aqueous electrolyte exhibits high electrochemical performances, such as an initial capacity of 258.5 mAh g-1 at 0.2 A g-1, and about 74.6% retention after 100 cycles with near 100% Coulombic efficiency. The strategy of conductive polymer coating makes the technology of rechargeable zinc-ion batteries (ZIBs) very promising and provides opportunities of organic-inorganic composite materials for energy storage applications.