High-performance zinc-ion batteries cathode material ZnMn2O4 modified by polypyrrole and reduced graphene oxide

Spinel zinc manganate has great prospects due to its advantages of a high voltage platform, non-toxicity, low cost, and abundant resources as a cathode material for ZIBs. However, its inherent poor conductivity and unsatisfactory long-term cyclic stability seriously restrict its commercial applications. Herein, the highly conductive polymer polypyrrole-coated ZnMn2O4 nanoparticles anchored on reduced graphene oxide with strong interfacial interaction (ZMO/rGO-PPy composite) were successfully synthesized. Compared with the pure ZnMn2O4 nanoparticles, ZMO/rGO-PPy composite displays increased conductivity of 3.89 x 103 S m-1 and higher discharge capacity of 269.6 mAh g-1 at 0.2 A g-1, as well as better rate capability and long-term cycling stability (after 900 cycles at a high current density of 1 A g-1 the specific capacity remains at 147.4 mAh g-1, with a capacity retention rate of 88.7%). The excellent performance is attributed to the shortened ion diffusion pathway, improved electrical conductivity and good structure stability. Furthermore, electrochemical analyses reveal that favorable reaction kinetics towards efficient zinc ion storage is achieved in the composite. These results suggest ZMO/rGO-PPy composites could be a competitive cathode material for ZIBs.