Cu粉和Ni粉添加剂对V20Ti30Cr50贮氢合金电化学性能的影响

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.

Influence of Cu and Ni additives on the electrochemical performance of V20Ti30Cr50 BCC hydrogen storage alloy

The electrochemical performances of V_(20)Ti_(30)Cr_(50) alloy manually mixed or manually mixed and then sintered with Cu or Ni powders were investigated.It was found that V_(20)Ti_(30)Cr_(50) 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 V_(20)Ti_(30)Cr_(50) alloy electrode decreased to 30mAh/g because of the formation of Cu_4Ti_3 compounds,and the discharge plateau potential was the same as before.The discharge capacity of V_(20)Ti_(30)Cr_(50) 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.