以单质元素粉末为原料,采用1500℃高温反应合成不同成分的钒硼化物粉末,并以制备粉末为活性物质,Ni为导电剂,NH4HCO3为造孔剂,采用粉末冶金工艺制备了多孔V-xB/Ni型(x=2/3～2)负极电极片,探讨不同物相钒硼化物作为空气电池电极活性物质的高容量输出性能.结果表明,当原料粉末中V∶B原子比为1∶1、1∶2时,可分别制得具有单一物相的VB和VB2化合物粉末,当V∶B=3∶2时,合成产物包含V3B2和少量VB相,当V∶B=2∶3时,合成产物为V2B3、V3B4和少量VB2三相混合.制备的V-xB/Ni型电极的孔隙率为60.25～61.75％,放电容量为6129～7901 mAh,比容量为2724～3511 mAh/g.V-xB/Ni型电极的放电性能随着B含量的增加明显提升,所制备V-2B/Ni型电极的放电性能最优,其比容量为3512 mAh/g,库伦效率为86.5％,能量密度达到2504Wh/kg.
Vanadium boride compound powders with different compositions were prepared by reactive synthesis at 1500℃ from elemental powders.Then,with the obtained powders as active materials,Ni powder as conductive agent and NH4HCO3 as space-holder,the porous anodes of V-xB/Ni (x=2/3～2) were fabricated by powder metallurgy (PM),respectively.The effects of V-xB compounds with different phases on the discharge performance of the assembled air batteries were studied.The results show that the single-phased VB2 powder can be obtained from the raw powder with the atomic ratio of V∶B=1∶2,and so does the VB powder.As for atomic ratio of V∶B=3∶2,the synthesized powder consists of V3B2 and a small amount of VB,while the ratio of V∶B=2∶3 yields the phase composition of V2B3,V3B4 and minor VB2.The prepared V-xB/Ni anodes with porosity of 60.25％-61.75％ exhibit good discharge performance,and their capacity can reach the range of 6129-7901 mAh while specific capacity is 2724-3511 mAh/g.With the increase of B content,the discharge performance of V-xB/Ni anodes shows a significant improvement.In comparison,the porous V-2B/Ni anode possesses the superior discharge properties with discharge capacity of 3512 mAh/g,coulombic efficiency of 86.5％ and specific energy of 2504 Wh/kg.
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