Fabrication of porous polyaniline/MWCNTs coated Co9S8 composite for electrochemical hydrogen storage application.

Mechanical alloying is used to obtain the Co 9 S 8 hydrogen storage material. The porous polyaniline (PPANI) with sea urchin-like morphology is synthesized via a facile saturated solution synthetic route. The porous polyaniline/multi-walled carbon nanotubes (PPANI/MWCNTs) composite is prepared by a solution-assisted self-assembly route. In order to improve the electrochemical performance of Co 9 S 8 , composites of Co 9 S 8 doped with PPANI, MWCNTs and PPANI/MWCNTs are fabricated by ball-milling. As the negative electrodes of Ni-MH batteries, the electrochemical properties of samples are measured utilizing a three-electrode system with the LAND CT2001A tester. Eventually, the composites exhibit superior discharge capacities than original Co 9 S 8 material. Moreover, PPANI/MWCNTs coated Co 9 S 8 electrode shows preferable discharge capacity compared with single MWCNTs or PPANI modified Co 9 S 8. The Co 9 S 8 + PPANI/MWCNTs electrode obtains a maximum discharge capacity of 689.2 mAh/g. In addition, the better high-rate dischargeability, enhanced corrosion resistance and preferable kinetic performance are also obtained for Co 9 S 8 + PPANI/MWCNTs. The improved electrochemical activity and kinetic properties of Co 9 S 8 are attributed to the synergistic effect between PPANI and MWCNTS species, which may further accelerate the hydrogen transmission and promote the charge transfer during the charge/discharge process. [Display omitted] • The PPANI/MWCNTs composite is prepared by a solution-assisted self-assembly route. • Co 9 S 8 material doped with porous PPANI/MWCNTs is synthesized by ball milling. • The discharge capacity, cycling stability and HRD of composite electrodes are enhanced. • The hydrogen diffusion was accelerated due to synergistic effect of PPANI and MWCNTs. [ABSTRACT FROM AUTHOR]