Microstructure and electrochemical characteristics of Ti0.17Zr0.08V0.34Nb0.01Cr0.1Ni0.3 hydride alloy

Microstructure and electrochemical properties of Ti0.17Zr0.08V0.34Nb0.01Cr0.1Ni0.3 hydride alloy have been investigated by using XRD, SEM-EDS, ICP and EIS measurements. The result of XRD analysis shows that the alloy is mainly composed of V-based solid solution phase with body-centered-cubic (bcc) structure and C14 Laves phase with hexagonal structure. V-based solid solution phase is dendrite embeds mainly in the matrix of C14 Laves phase. and the distribution of the component elements in the two phases has a mirror relationship. The maximum discharge capacity of Ti0.17Zr0.08V0.34Nb0.01Cr0.1Ni0.3 hydride alloy has reached 337.0 mAh(.)g(-1) with good cycle stability. The alloy electrode has a higher discharge capacity within a wide temperature region from 303 K to 343 K. and the discharge capacity is 327.9 mAh(.)g(-1) at 343 K. ICP analyses indicate that the dissolution of V and Zr to KOH solution is rather seriously. The result of electrochemical impedance spectrometry (EIS) indicates that the charge transfer resistance (R-T) increases with increasing cycle number and the exchange current density (I-0) decreases with increasing cycle number. The increase of R-T and the dissolution of V and Zr element are perhaps main factors affecting the discharge capacity.