Icosahedral quasicrystalline (Ti1.6V0.4Ni)100−xScx alloys: Synthesis, structure and their application in Ni-MH batteries

• Crystalline disallowed 5-fold symmetry is present in (Ti1.6V0.4Ni)100−xScx alloys.
• Ti-based metastable quasicrystalline alloys can store hydrogen electrochemically.
• A maximum discharge capacity of 270 mA h g−1 can be delivered.
• Advantageous cycle stability and self-discharge property benefit from Sc addition.
• Ti and V dissolution is suppressed by an oxide layer resulting from Sc corrosion.

Thanks to the revolutionary discovery of 5-fold symmetry contributed by Shechtman, quasicrystal is now recognized as another solid-state existing form. As the second largest class of quasicrystals, titanium-based icosahedral quasicrystals are very promising for hydrogen storage applications owing to their inherent abundant interstitial sites and favorable hydrogen-metal chemistry. In this context, (Ti1.6V0.4Ni)100−xScx (x=0.5–6) quaternary icosahedral quasicrystals have been successfully synthesized via arc-melting and subsequent melt-spinning techniques, and then their electrochemical performance toward hydrogen is explored. When the molar ratio of Sc addition is under 1%, a maximum discharge capacity of about 270 mA h g−1 can be delivered. With further increasing Sc amount to 6%, good cycling stability as well as significantly retarded self-discharge rate (capacity retention 94% after 24 h relaxation) is observed. But meanwhile, the discharge capacities fall into 250-240 mA h g−1, and the electrocatalytic activity improvement is highly demanded.

Quasicrystalline Ti–V–Ni–Sc hydrogen storage materials: Sc addition into Ti1.6V0.4Ni alloy forms the icosahedral phase (see picture). With optimal Sc dosage, the anodic cycling stability and self-discharge property are greatly enhanced.Figure optionsDownload as PowerPoint slide