Electrochemical performances of Mg₄₅M₅Co₅₀ (M=Pd, Zr) ternary hydrogen storage electrodes

In order to improve the discharge capacity and cyclic life of Mg–Co-based alloy, ternary Mg₄₅M₅Co₅₀ (M=Pd, Zr) alloys were synthesized via mechanical alloying. TEM analysis demonstrates that these alloys all possess body-centered cubic (BCC) phase in nano-crystalline. Electrochemical experiments show that Mg₄₅Zr₅Co₅₀ electrode exhibits the highest capacity (425 mA·h/g) among the Mg₄₅M₅Co₅₀ (M=Mg, Pd, Zr) alloys. And Mg₄₅Pd₅Co₅₀ electrode lifts not only the initial discharge capacity (379 mA·h/g), but also the discharge kinetics, e.g., exchange current density and hydrogen diffusion ability from that of Mg₅₀Co₅₀. It could be concluded that the electrochemical performances were enhanced by substituting Zr and Pd for Mg in Mg–Co-based alloy.