Graphene-wrapped hollow ZnMn2O4 microspheres for high-performance cathode materials of aqueous zinc ion batteries

Spinel zinc manganate as a promising cathode material of zinc ion batteries (ZIBs) has received extensive attention owing to its advantages of high voltage platform, high abundance of raw material, low cost, non-toxicity and environmental friendliness. However, its inherent poor electrical conductivity and large volume expansion usually result in a low specific discharge capacity, fast capacity decay and poor cycling stability, which hinder its practical application. To alleviate these problems, graphene-wrapped hollow ZnMn2O4 microspheres (rGO@HM-ZMO) were prepared. The attachment of rGO successfully enhances the electronic conductivity and decreases the charge transfer resistance, and the hollow architecture can effectively alleviate the changes of crystal structure during the repeated Zn2+ insertion/extraction process. The resulting rGO@HM-ZMO electrode exhibits a superior specific discharge capacity of 146.9 mAh g(-1) after 100 cycles at 0.3 A g(-1) and impressive cycling stability which retains a capacity of around 72.7 mAh g(-1) without fading after 650 cycles at a high rate of 1 A g(-1), which are superior to some reported cathode materials of ZIBs. These electrochemical results suggest the rGO@HM-ZMO composite could be a competitive cathode material of ZIBs. (C) 2019 Elsevier Ltd. All rights reserved.