【摘要】 采用XRD的Rietveld全谱拟合技术以及利用储氢合金吸氢量与其体积膨胀成线形关系的原理,研究了Ti-V基贮氢电极合金的电化学吸放氢机理.结果表明,铸态合金Ti0.8Zr0.2V1.867Mn0.373Cr0.56Ni0.7由C14型Laves相和V基固溶体相构成.在充电过程中,充电时间由3.33增至120 min时,Laves相的晶胞体积膨胀率ΔV/V分别由0.301％增加到2.719％,而V基同溶体相的ΔV/V由0.011％增至1.685％.在放电过程中,放电时间从0 min增加到165 min时,Layes相的ΔV/V从14.542％降到8.119％;而V基固溶体相的△V/V从8.117％减小到6.248％.说明电化学吸氢时,氢首先被Laves相吸收,然后再扩散进入V基固溶体;电化学放氢时, V基固溶体中的氢首先扩散进入Laves相然后再释放.因此,该合金中,Laves相既是吸氢相又是催化相,提高合金中V基固溶体相的利用率,从而使Ti-V基贮氢合金具有较好的综合电化学性能.更多还原

【Abstract】 The electrochemical hydrogenation and dehydrogenation mechanisms of a multiphase Ti-V base alloy Ti0.8Zr0.2V1.86/Mn0.373Cr0.56Ni0.7 have been studied by XRD Rietveld analyses, based on the linear relationship between the volume expansion and charging capacity. The results show that the as-cast alloy is composed of a C14 Laves phase with hexagonal structure and a V base solid solution phase with bcc structure. During electrochemical charging, the unit cell volume expansion (ΔV/V) of the Laves phase is from 0.301% to 2.719% and for the bcc phase from 0.011% to 1.685% for the charging durations from 3.33 min to 120 min, respectively. During electrochemical discharging (ΔV/V) of the Laves phase decreases from 14.542% to 8.119% and for the bcc phase from 8.117% to 6.248% for the discharging durations from 0 min to 165 min, respectively. Therefore, during electrochemical charging, the Laves phase was hydrogenated from very beginning of the charging process. The bcc phase could obtain hydrogen only from its neighboring Laves phase. The electrochemical discharging mechanism is similar to that of charging. In conclusion, C14 Laves phase and V base solid solution phase are the hydrogen storage phases with high hydrogen storage capacities in the alloy Ti0.8Zr0.2V1.867Mn0.373Cr0.56Ni0.7; C14 Laves phase also works as an electrochemical catalyst for the V base solid solution phase, which enhances the use of V base solid solution phase to make electrochemical properties of Ti-V base multiphase hydrogen storage electrode alloys preferable.更多还原