Quinary icosahedral quasicrystalline Ti–V–Ni–Mn–Cr alloy: A novel anode material for Ni-MH rechargeable batteries

The substitution of manganese and chromium for 6 at.% nickel in Ti1.6V0.4Ni leads the rapid quenching synthesis of quinary icosahedral phase (i-phase) evidenced by the observations of 2-, 3- and 5-fold symmetries. As negative electrode in Ni-MH battery, the quinary Ti–V–Ni–Mn–Cr i-phase can deliver a maximum discharge capacity of 278 mAh g−1 at 30 mA g−1, larger than that of Ti1.6V0.4Ni master alloy anode owing to Mn and/or Cr doping. After a preliminary test of 30 consecutive cycles the cycling capacity retention rate (CR%) is 80%. The strong chemisorption of hydrogen shown in cyclic voltammetric (CV) response indicates that the electrocatalytic activity improvement for the i-phase negative electrode is highly demanded.

The discovery of quinary Ti–V–Ni–Mn–Cr icosahedral quasicrystalline phase is evidenced by the detection of crystallographically disallowed 5-fold SAED pattern. As a negative electrode material in Ni-MH battery, a maximum discharge capacity up to 278 mAh g−1 can be delivered, and a capacity retention rate after 30 cycles of charge–discharge is kept at 80%.Figure optionsDownload as PowerPoint slideHighlights
► Ti–V–Ni–Mn–Cr quinary quasicrystalline alloys as hydrogen storage materials.
► Forbidden 5-fold symmetry with anisotropic diffraction spots of an icosahedron.
► Nickel-enriched Ni4Ti3 phase serves as electrocatalytic active sites.
► Higher discharge capacity 278 mAh g–1 than that of Ti-V-Ni profits from Mn addition.
► Cr slows down dissolution rate of active constituents V and Mn at the expense of HRD.