α-MnO2 film was conveniently synthesized on the three-dimensional (3D) Ni foam via a simple, low cost, safe and practical chemical bath deposition at room temperature. The obtained film was characterized by X-ray diffraction, scanning electron microscopy, infrared spectroscopy, thermogravimetric-differential scanning calorimetry analysis and electrochemical workstation. Results showed that the as-synthesized film had an amorphous nature and double 3D porous structure with the 3D Ni foam, and the prepared film electrode exhibited the excellent power capability and large special capacitance with a maximum capacitance of 500.5 F g− 1. This simple synthetic approach may provide a convenient route for the preparation of double 3D MnO2 film with high surface area and capacitance on a large scale.
