Electrochemical properties of Mg 3 MnNi 2 - x % polymethyl methacrylate-multiwalled carbon nanotubes (PMMA-MWCNTs) ( x = 25, 50, 75, 100)

In this work, we report a novel core–shell-like structure of uniform coating PMMA-MWCNTs composite film on the surface of the Mg3MnNi2 alloy particles prepared by hydriding combustion synthesis. The structures and electrochemical performances of Mg3MnNi2 alloy with different PMMA-MWCNTs coating content have been studied in detail. Results show that the PMMA-MWCNTs composite film has no effect on the phase composition of Mg3MnNi2 alloy and the composite film has been successfully coated on the surface of Mg3MnNi2 alloy with a thickness of about 30 nm. In addition, MWCNTs are dispersed in the PMMA layer successfully, improving the electrochemical catalytic activity and working as a conductive path and a hydrogen diffusion channel as well. It is found that the coating of proper amount of PMMA-MWCNTs film can enhance obviously the cycling stability of the alloy electrode. The Mg3MnNi2-75% PMMA-MWCNTs sample exhibits the best overall electrochemical properties, with the best cycling stability, the optimal high-rate dischargeability, the maximum exchange current density and the minimum charge-transfer resistance (Rct).