The electrochemical charge-discharge properties of ZrCrNi hydrogen storage alloys
1995; Elsevier BV; Volume: 231; Issue: 1-2 Linguagem: Inglês
10.1016/0925-8388(95)01730-5
ISSN1873-4669
AutoresYongquan Lei, Yang Xiaoguang, Jing Wu, Qidong Wang,
Tópico(s)Fuel Cells and Related Materials
ResumoZr(CrxNi1−x)2(0.15 ⩽ x ⩽ 0.65) alloys were prepared by arc melting in an argon atmosphere. Through X-ray diffraction, the main crystal structure of the alloys was found to change from Laves phase cubic C15 to hexagonal C14 as the CrtoNi ratio increased, and lattice parameters and hydrogen absorption capacities were mainly determined by the Cr content. The alloy Zr(Cr0.35Ni0.65)2, which was mainly of C15 Laves phase structure, was found to have maximum electrochemical discharge capacity of 305 mA h g−1 at 298 K. The activation behaviors of ZrCrNi-based hydride electrodes were also studied. Fine alloy powders, especially those pulverized by cycling in hydrogen gas and where the electrodes were pre-treated with HF-H2O2 solution, were highly activated. As both Zr and Cr have a high resistance against alkaline solution, it is reasonable for ZrCrNi alloy electrodes to have durable cycle lives. The chemical valence states and composition of electrode surfaces were also analyzed with X-ray photoelectron spectroscopy before and after charge-discharge cycling. An obvious variation in the Zr 3d5/2 peak position before and after cycling was detected. The discrepancy is ascribed to the chemical environment differences of Zr atom in primordial and activated surface layers.
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