La_(2-x)Sm_(x)Mg_(16)Ni(x=0.1~0.4)+100%Ni+5%石墨烯复合储氢合金电化学性能

Electrochemical performance of La_(2-x)Sm_(x)Mg_(16)Ni(x=0.1-0.4)+100%Ni+5%graphene composite hydrogen storage alloys

通过真空感应熔炼炉冶炼La_(2-x)Sm_(x)Mg_(16)Ni(x=0.1~0.4)合金。将Ni粉、石墨烯和La_(2-x)Sm_(x)Mg_(16)Ni(x=0.1~0.4)合金粉球磨10 h制备出La_(2-x)Sm_(x)Mg_(16)Ni(x=0.1~0.4)+100%(质量分数)Ni+5%(质量分数)石墨烯的复合储氢合金。对复合储氢合金进行XRD分析及电化学性能测试。研究元素取代、添加催化剂和机械球磨多元改性对储氢合金相结构和电化学性能的影响。实验结果表明La_(2-x)Sm_(x)Mg_(16)Ni(x=0.1~0.4)+100%(质量分数)Ni+5%(质量分数)石墨烯复合储氢合金组成相为Ni,La_(2)Mg_(17)和La_(2)Ni_(3)相。多元改性后的储氢合金都具有良好的活化性能,第一次充放电就达到了最大放电比容量。Sm的取代量x=0.3时,La_(1.7)Sm_(0.3)Mg_(16)Ni+100%(质量分数)Ni+5%(质量分数)石墨烯的复合储氢合金放电比容量最大为88.7 mAh/g;循环稳定性最好S_(50)=73.63%。随着Sm元素取代量增加,复合储氢合金电极的高倍率放电HRD、极限电流密度IL和氢扩散系数D都呈先增大后减小的趋势,当Sm的取代量x=0.3时,其值达到最大分别为:HRD_(1500)=28.55%,I_(L)=1754 mA/g,D=1.86×10^(-10) cm^(2)。

The La_(2-x)Sm_(x)Mg_(16)Ni(x=0.1~0.4)alloys are smelted through a vacuum induction melting furnace.Ni powder,graphene and La_(2-x)Sm_(x)Mg_(16)Ni(x=0.1~0.4)alloy powder were ball milled for 10 h to prepare La_(2-x)Sm_(x)Mg_(16)Ni(x=0.1~0.4)+100 wt%Ni+5 wt%graphene composite hydrogen storage alloys.XRD analysis and electrochemical performance test of the composite hydrogen storage alloy.The effects of element substitution,addition of catalysts,and mechanical ball-milling multiple modifications on the phase structure and electrochemical performance of hydrogen storage alloys are studied.The experimental results showed that La_(2-x)Sm_(x)Mg_(16)Ni(x=0.1~0.4)+100 wt%Ni+5 wt%graphene composite hydrogen storage alloys were composed of Ni,La_(2)Mg_(17),and La_(2)Ni_(3) phases.The hydrogen storage alloys after multi-element modification had good activation properties,and the maximum discharge specific capacity were reached at the first charge and discharge.When the substitution amount of Sm _(x)=0.3,the maximum discharge specific capacity of the composite hydrogen storage alloy of La_(1.7)Sm_(0.3)Mg_(16)Ni+100 wt%Ni+5 wt%graphene was 88.7 mAh/g.The best cycle stability was S50=73.63%.With the increase of Sm element substitution,the high-rate discharge HRD,limiting current density IL,and hydrogen diffusion coefficient D of the composite hydrogen storage alloy electrode increased at first and then decreased.When the substitution amount of Sm x=0.3,the maximum values were:HRD_(1500)=28.55%,I_(L)=1754 mA/g,D=1.86×10^(-10) cm^(2).