In-situ Co-precipitated α-MnO2@2-methylimidazole cathode material for high performance zinc ion batteries

Abstract

Zinc ion batteries (ZIBs) are newly emerging and widely attracted energy storage devices owing to its advantages of intrinsic safety and low-cost effectiveness. Herein, we reported a nanorod-like MnO2 cathode material composited with carbon and pyrrolic nitrogen by in-situ co-precipitation method at room temperature, which was used as ZIB cathode to deliver a high specific capacity of 339 mAh g−1 at 100 mA g−1 and a long cycle stability over 2000 cycles at 1000 mA g−1, resulting in the ultrahigh coulombic efficiencies approximate to 100%. The improved performance was attributed to the enhancement of structural stability and more zinc ion insertion sites after introducing the 2-methylimidazole (2-MI) coating layer. The phase transition of α-MnO2 @2-methylimidazole (α-MnO2 @2-MI) and the formation of more porous architecture could be the origin of the continuous capacity increasing in the initial several cycles, which was proved by the results of the ex-situ x-ray diffraction (XRD) and the scanning electronic microscope (SEM). This method can be a more realistic choice for the further commercial applications of low-cost and easily-accessed ZIBs with excellent electrochemical performance.