An electroless copper plating method for Ti, Zr-based hydrogen storage alloys

An acidic electroless copper plating method using HF has been developed and applied to the hydrogen storage alloy: Zr0.5Ti0.45V0.54Ni0.87Cr0.15Co0.21Mn0.24. It is shown that the copper plating mechanism is an ion-exchange process between alloy elements and copper ions. The resulting copper coating is metallic. The coated copper layer significantly improved activation properties of the alloy electrode for a Ni–MH secondary battery. Anodic polarization curves and SEM micrographs showed that the reason for this improvement is due to the dissolution of a surface oxide film by HF during the copper plating. This coating method was also successfully applied to eight other Zr(Ti) alloy powders with different compositions. It can be concluded that this electroless copper plating method can be widely applied to Ti(Zr)-based hydrogen storage alloys of various compositions which had been regarded to be difficult to coat by conventional electroless copper plating methods.