Electrode properties and microstructures of MnO2 nanosheet thin films as cathodes for electrochemical capacitors

► Thin films of MnO2 nanosheets (NS) were prepared by electrophoretic deposition. ► Small-NS films had a heterogeneous microstructure with numerous pores. ► Small-NS films exhibited better electrochemical properties than large-NS films. ► The better electrochemical properties resulted from the fast ion diffusion. ► Heterogeneous microstructure was found to contribute to the good electrode properties.