Direct and low energy electrolytic co-reduction of mixed oxides to zirconium-based multi-phase hydrogen storage alloys in molten salts
Direct and low energy electrolytic co-reduction of mixed oxides to zirconium-based multi-phase hydrogen storage alloys in molten salts
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DOI：
10.1039/b820560d
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发表时间：
2009-04
影响因子：
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通讯作者：
Junjun Peng;Yong Zhu;Dihua Wang;Xianbo Jin;G. Chen;G. Chen
中科院分区：
文献类型：
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作者：
Junjun Peng;Yong Zhu;Dihua Wang;Xianbo Jin;G. Chen;G. Chen
在900 °C和低于3.2V的电解槽电压下，以混合氧化物为前驱体，采用电解法直接合成了Zr基AB 2型贮氢合金。该过程类似于固态氧化物直接转化为金属，目标合金ZrCr 2，ZrCr 0.7Ni 1.3和Zr 0.5Ti 0.5V 0.5Cr 0.2Ni 1.3，在电解过程中原位形成，而不经过任何熔化步骤。电解能耗可低至9.59 kWh（kg-HSA）−1，金属回收率通常高于90%。电解产物作为具有指定组成和晶体结构（例如C14和C15 Laves相）的粉末容易地获得。更重要的是，这些Zr基电解HSA粉末由结节状微粒组成，这对于制造具有微孔的电极以促进电解质的进出是非常理想的。所制备的电解HSA粉末的恒电流放电-充电测试导致与文献中报道的通过例如电弧熔化单个金属制备的相同HSA相比类似或更高的储氢容量（高达280 mAh g-1）。特别地，电解Zr基HSAs的独特之处在于它们的高初始容量，而无需任何活化预处理，并且它们还表现出高度令人满意的放电倍率性能，当放电电流从50增加到600 mA g-1时，容量损失小于20%。
Direct synthesis of Zr-based AB2-type hydrogen storage alloys (HSAs) from mixed oxide precursors has been achieved by electrolysis in molten CaCl2 at 900 °C and a cell voltage below 3.2 V. The process resembled direct oxide-to-metal conversion in solid state, and the target alloys, namely ZrCr2, ZrCr0.7Ni1.3 and Zr0.5Ti0.5V0.5Cr0.2Ni1.3, were formed in situ during electrolysis without going through any melting step. Electrolysis energy consumption could be as low as 9.59 kWh (kg-HSA)−1 and the metal recovery yield was generally higher than 90%. The electrolytic products were readily obtained as powders with the designated compositions and crystal structures (e.g. the C14 and C15 Laves phases). More importantly, these Zr-based electrolytic HSA powders were composed of nodular micro-particles which are very desirable for fabrication of electrodes with micro-porosity to facilitate electrolyte ex- and ingression. Galvanostatic discharge-charge tests of the as-prepared electrolytic HSA powders resulted in similar or higher hydrogen storage capacities (up to 280 mAh g−1) in comparison with the same HSAs prepared by e.g. arc-melting the individual metals as reported in literature. Particularly, the electrolytic Zr-based HSAs were unique for their high initial capacities without any pre-treatment for activation, and they also exhibited highly satisfactory discharge rate capability with less than 20% capacity loss when the discharge current increased from 50 to 600 mA g−1.