氧含量对V_(2-x)Ti_(0.5)Cr_(0.5)NiO_x(x=0~0.35)贮氢合金组织结构和电化学性能的影响(英文)

Influence of Oxygen Content on Microstructure and Electrochemical Properties of V_(2-x)Ti_(0.5)Cr_(0.5)NiO_(x) (x=0~0.35) Hydrogen Storage Alloys

为了提高V基固溶体贮氢合金的充放电循环稳定性能,研究了O含量对V2-xTi0.5Cr0.5NiO x（x=0~0.35）合金的组织结构和电化学性能的影响。组织结构分析表明,当没有添加O时,合金主要由bcc结构的V基固溶体相和TiNi相组成,随着O含量的增加,合金中出现了Ti4Ni2O新相。电化学测试表明,随着O含量的增加合金电极的最大放电容量有所降低,从x=0时的366.8 mAh/g降低到x=0.35时的225.3 mAh/g,而较少氧含量时,合金电极的循环稳定性能明显得到了改善,从x=0时的69.9%增大到x=0.2时的83.7%,而后又降低到76.9%（x=0.35）。电化学动力学分析结果表明,合金的高倍率放电性能,交换电流密度和氢的扩散系数均随着O含量的增加先增加而后减小。

To improve the charge-discharge cycle stability of V-based hydrogen storage alloys, the different contents of oxygen（O）element were introduced into the V2Ti0.5Cr0.5Ni alloy, and the structures and electrochemical properties of the V2-x Ti0.5Cr0.5NiO x（x=0~0.35） alloys were investigated. The structural investigations show that the alloys with lower O content mainly consist of a V-based solid solution phase with a bcc structure and a Ti Ni-based secondary phase, while a new phase Ti4Ni2 O is observed for the alloys with higher O content. With increasing of O content, the maximum discharge capacity for the V2-xT i0.5Cr0.5NiO x（x =0~0.35）alloy electrodes decreases from 366.8 mA h/g（x=0） to 225.3 mA h/g（x=0.35）, while the cycle stability of the alloy electrodes first increases from 69.9%（x=0） to 83.7%（x=0.2） and then decreases to 76.9%（x=0.35）. Moreover, the high rate discharge ability, the exchange current density and the hydrogen diffusion coefficient of the alloys first increase and then decrease with increasing of O content.