Cu粉和Ni粉添加剂对V_(20)Ti_(30)Cr_(50)贮氢合金电化学性能的影响

Influence of Cu and Ni additives on the electrochemical performance of V_(20)Ti_(30)Cr_(50) BCC hydrogen storage alloy

采取手工混合和混合加烧结的方法,研究了Cu粉和Ni粉添加剂对V20Ti30Cr50贮氢合金电化学性能的影响。结果表明:烧结前,添加铜粉的V20Ti30Cr50合金的电极具有较高的放电容量,其最大放电容量为342.7mAh/g,但放电平台电压较低,仅为-0.4V(相对于Hg/HgO电极),而添加镍粉的合金电极的最大放电容量仅为73.4mAh/g,没有明显的放电平台;烧结后,添加铜粉的电极由于表面Cu4Ti3化合物的生成,电极的放电容量降低到30mAh/g,放电平台电压仍仅为-0.4V,而烧结的添加镍粉的电极合金与镍粉表面结合紧密,同时有TiNi第二相的生成,增加了合金电极表面的电催化活性,合金的放电平台电压提高到-0.8V,并且最大放电容量显著增加到209mAh/g。

The electrochemical performances of V20Ti30Cr50 alloy manually mixed or manually mixed and then sintered with Cu or Ni powders were investigated. It was found that V20Ti30Cr50 alloy electrode manually mixed with Cu powder showed a discharge capacity of 342.7mAh/g, while its discharge plateau potential was as low as -0.4V/（vs Hg/HgO）. The electrode manually mixed with Ni powder had a discharge capacity of 73.4mAh/g, and didn＇t show any flat region in the discharge curve. After manually mixed and then sintered with Cu powder, the discharge capacity of V20Ti30Cr50 alloy electrode decreased to 30mAh/g because of the formation of Cu4Ti3 compounds, and the discharge plateau potential was the same as before. The discharge capacity of V20Ti30Cr50 alloy electrode manually mixed and then sintered with Ni powder increased to 209mAh/g and its discharge plateau potential increased to -0.8V. It is contributed to a tight contact between the surfaces of the alloy and the Ni powders and a formation of the catalyzing second phase TiNi during sintering.