超化学计量比Ti-Zr-V-Mn-Cr-Ni贮氢电极合金相结构及电化学性能研究

研究了超化学计量比对钛基贮氢合金相结构及电化学性能的影响。XRD及EDS分析表明，超化学计量比贮氢合金（Ti0.8Zr0.2)(V0.533Mn0.107Cr0.16Ni0.2)x(x=2,3,4,5,6)均主要由六方结构的C14型Laves相和体心立方结构的钒基固溶体相构成。随着x值的增大，两相的晶胞参数及晶胞体积均减小。电化学性能测试表明，当x的值在2－5范围内时，随着x值的增大，合金的最大放电容量、放电电位、高倍率放电性能（HRD）、循环稳定性、交换电流密度I0以及极限电流密度IL均提高。但继续增大x值后，除放电电位、高倍率放电性能和循环稳定性继续有所提高外，最大放电容量、交换电流密度I0以及极限电流密度IL均减小。此外，随着化学计量比的增大，合金电极的活化渐趋困难。

INVESTIGATION ON THE STRUCTURE AND ELEC TROCHEMICAL PROPERTIES OF SUPER-STOICH IOMETRIC Ti-Zr-V-Mn-Cr-Ni HYDROGEN STORAGE ELECTRODE ALLOYS

The structure and electrochemical properties of the super-stoichiometric Ti-based hydrogen storage alloys (Ti0.8Zr0.2)(V0.533Mn0.107Cr0.16Ni0.2)x (x=2, 3, 4, 5, 6) have been studied. It is found by XRD and EDS analysis that these alloys all mainly consist of two phases: a C14 type Laves phase with hexagonal structure and a V-based solid solution phase with bcc structure. The lattice parameters and unit cell volumes of the two phases all decrease with increasing x. The electrochemical studies show that the maximum discharge capacity, the discharge potential, the high rate dischargeability (HRD), the cyclic stability, the exchange current density Io and the limiting current density IL of the alloys all increase with increasing x from 2 to 5. When x reaches 6, the discharge potential, HRD and cyclic stability are still increasing proportionately, while the maximum discharge capacity, I0 and IL all decrease. Furthermore, the alloy electrodes become more difficult to be activated for the higher stoichiometric alloys.