| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1615459 | Journal of Alloys and Compounds | 2012 | 5 Pages |
The effect of annealing time on the structure and electrochemical properties of La0.72Nd0.08Mg0.2Ni3.4Al0.1 hydrogen storage alloys was investigated. The alloys were annealed at 1173 K for different time, and the results of Rietveld refinement for the XRD data showed that the alloys were composed of Gd2Co7-type, Ce2Ni7-type, Pr5Co19-type, PuNi3-type, LaNi5-type and MgCu4Sn-type phases. Lengthening annealing time obviously promoted the formation of Gd2Co7-type phase which possessed high hydrogen storage capacity, and the largest content of Gd2Co7-type phase was obtained when the alloys were annealed for 20 h. The maximum discharge capacity increased from 365.0 (as-cast) to 389.6 mAh/g (annealed for 20 h), which was ascribed to Gd2Co7-type phase abundance increasing from 35% (as-cast) to a maximum (81.71%, annealed for 20 h). Also, the discharge capacity retention over 180 cycles at charge/discharge current density of 300 mA/g was remarkably heightened from 56.6% (as-cast) to 80.5% (annealed for 20 h). In addition, annealing treatment at 1173 K for 6 h can enhance high rate discharge ability.
► Lengthening annealing time increases discharge capacity and cyclic stability. ► Lengthening annealing time promotes the formation of Gd2Co7-type phase. ► The maximum discharge capacity reaches 389.6 mAh/g. ► The cyclic stability remains 80.5% over 180 cycles.
