A composite based on Fe substituted TiVNi alloy: Synthesis, structure and electrochemical hydrogen storage property

The TiV(1-x)NiFex (x = 0, 0.1, 0.2, 0.3 and 0.4) alloy ribbons are synthesized by arc-melting and subsequent melt-spinning techniques. The structure of the alloys is characterized by XRD. The electrochemical properties including the maximum discharge capacity, cyclic stability and the high rate dischargeability, etc. are tested. The results show that the structure of all TiVNi alloy mainly consists of the icosahedral quasicrystal (I-phase), Ti2Ni-type face centered cubic (FCC) phase and body centered cubic (BCC) solid solution phase. After adding some amount of Fe to TiVNi alloys, for TiV0.9NiFe0.1 (x = 0.1) alloy, the XRD pattern is characterized by the FCC and the BCC phase, while the structure of TiV1-xNiFex alloys (x = 0.2, 0.3 and 0.4) consists of the BCC solid solution phase alloy. The maximum discharge capacity of the alloy electrodes increases firstly and then decreases with increasing x, the same as the high-rate dischargeability. The optimal value of C-240/C-30 is 84.2%, corresponding to x being 0.2 and the discharge current density is 240 mA/g. In addition, the electrochemical reaction kinetics of the alloy electrodes is also studied by electrochemical impedance spectroscopy and hydrogen diffusion coefficient (D). (C0 2012 Elsevier Ltd. All rights reserved.