Electrochemical properties of Mg₃MnNi₂-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 (R_ct).