熔炼掺杂对AB_5型贮氢合金的结构和性能影响

Structure and properties of melting-doped AB_5 hydrogen storage alloys

为了探索一种新的掺杂方式对AB5型贮氢合金性能的影响,采用熔炼掺杂方法,研究了掺杂适量TiMn1.5合金(掺杂量为4%、8%的TiMn1.5)对成分为La0.7Ni2.65Co0.75Mn0.1的AB5型贮氢合金的结构及性能影响。XRD测试结果证实:掺杂后合金的主相仍为LaNi5相,生成了少量(NiCo)3Ti相。(NiCo)3Ti相的出现对贮氢合金的气态和电化学贮氢性能都有不同程度的降低。合金电极的动力学测试结果表明(线性扫描法和交流阻抗法):在0.5～2.5C的放电电流密度,掺杂前后的合金电极的反应速率均由电极表面电荷转移速率决定,掺杂4%TiMn1.5的合金样品电极的高倍率放电性能有一定的改善。在3C放电电流密度以上,电极反应速率均由氢扩散速率来控制,随着TiMn1.5的掺杂的增加,其合金电极的高倍率性能降低。

To Search the affection of a new way doping on ABs-type hydrogen storage alloys, La0.7 Ni2.65 Coo. 7s Mn0.1 （AB5 type） hydrogen storage alloys, melting-clopped with TiMnl.s alloy （4 %, 8 %）, have been investigated to illus- trate the effects of doping on its structure and properties. XRD analysis indicated that the dopped alloy samples con- sist of a main LaNis phase and small （NiCo）3 Ti phase, the formation of （NiCo）3 Ti phase will result in the decrease of hydrogenation and high-rate dischargeabilities. Further analysis of electrode kinetics were measured by linear po- larization and Electrochemical impedance spectroscopy （EIS）, the results presented that the electrode reaction was determined by charge-transfer reaction, and the electrode melting-dolaped with 4 % TiMnl. 5 alloy, shown better high- rate dischargeabilities, when discharged at the rate from 0.5 to 2.5 C. While, the electrode reaction was determined by hydrogen-diffusion reaction, and the high-rate disehargeabilities have been decreased with the increase of TiMn1.5 content, when discharged at the rate from 3.0 to 4.0 C.