Abstract AB2 alloys have been extensively studied as Ni-MH battery anodes. In the hydriding process, hydrogen diffusion inside the crystal lattice is the determining step, so a comparison between gas phase and electrochemical environment was carried out. As concern, we have found structural changes as a consequence of hydriding in terms of segregation of different stable phases and variations in unit cell parameters in each alloy. Maximum hydrogen storage capacity and hydrogen molar volume for studied alloys were evaluated by PCT curves at different temperatures. Resulting values were compared with electrochemical PCT (ECT plots). Results obtained for both methods were similar, with a hydrogen molar volume value close to 30 cm3 mol−1 being higher for AB2M0 in accordance with the reported capacity values. Diffusion time constants were determined from GITT, achieved data were similar to previously reported by EIS and HRD. AB2M1 alloy showed the best kinetic behavior, depicting a time constant value an order of magnitude lower than AB2M0. This fact could be attributed to the diffusion coefficient and/or the hydrogen diffusion length mean path. No significant differences in thermodynamic parameters were observed between both alloys, therefore, the diffusion coefficients should be similar. Thus, differences in time diffusion constants were attributed to dissimilar mean lattice diffusion paths associated with changes in crystalline structures as a result of the hydriding process.

中文翻译：

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AB2 氢化物合金中的储氢：扩散过程分析

摘要 AB2 合金作为镍氢电池负极已被广泛研究。在氢化过程中，晶格内部的氢扩散是决定性步骤，因此进行了气相和电化学环境的比较。值得关注的是，我们已经发现，在每种合金中不同稳定相的分离和晶胞参数变化方面，由于氢化而导致结构变化。通过不同温度下的 PCT 曲线评估了所研究合金的最大储氢容量和氢摩尔体积。将所得值与电化学 PCT（ECT 图）进行比较。两种方法获得的结果相似，根据报告的容量值，AB2​​M0 的氢摩尔体积值接近 30 cm3 mol-1 更高。扩散时间常数由 GITT 确定，获得的数据与之前由 EIS 和 HRD 报告的数据相似。AB2M1 合金表现出最好的动力学行为，其时间常数值比 AB2M0 低一个数量级。这一事实可归因于扩散系数和/或氢扩散长度平均路径。两种合金之间没有观察到热力学参数的显着差异，因此，扩散系数应该相似。因此，时间扩散常数的差异归因于与作为氢化过程的结果的晶体结构变化相关的不同平均晶格扩散路径。描绘了一个比 AB2M0 低一个数量级的时间常数值。这一事实可归因于扩散系数和/或氢扩散长度平均路径。两种合金之间没有观察到热力学参数的显着差异，因此，扩散系数应该相似。因此，时间扩散常数的差异归因于与作为氢化过程的结果的晶体结构变化相关的不同平均晶格扩散路径。描绘了一个比 AB2M0 低一个数量级的时间常数值。这一事实可归因于扩散系数和/或氢扩散长度平均路径。两种合金之间没有观察到热力学参数的显着差异，因此，扩散系数应该相似。因此，时间扩散常数的差异归因于与作为氢化过程的结果的晶体结构变化相关的不同平均晶格扩散路径。