Facile fabrication of multiwalled carbon nanotube/α-MnOOH coaxial nanocable films by electrophoretic deposition for supercapacitors

Multiwalled carbon nanotube (MWCNT)/α-MnOOH coaxial nanocable (MMCNC) films are successfully fabricated by a simple and low-cost electrophoretic deposition (EPD) process. The as-prepared MMCNC films exhibit three-dimensional (3D) nanoporous network structure. A possible mechanism is proposed to explain the formation of the MMCNC films. Electrochemical test results show that the films exhibit superior capacitive behaviors and cycle stability in 0.1 M Na ₂SO₄ aqueous solution. The thickness, mass loading and capacitive performance of the MMCNC films can be easily and continuously tuned by varying the deposition time. A relatively high mass specific capacitance of 327 F g^-1 is obtained from the films with relatively low mass loading of 0.05 mg cm^-2, while, a relatively high areal capacitance of 0.2 F cm^-2 is achieved when the mass loading was increased to 1.38 mg cm^-2. The superior capacitive performances can be attributed to the unique structure advantages of the MMCNC films. On one hand, the one-dimensional (1D) coaxial nanocable structure works, with MWCNT core serving as high electronic conductive frame and α-MnOOH sheath providing high pseudocapacitance. On the other hand, the 3D nanoporous network structure can facilitate fast ions transportation.