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Phase-structural transformations in a metal hydride battery anode La1.5Nd0.5MgNi9 alloy and its electrochemical performanceстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 19 декабря 2017 г.
- Авторы: Volodin A.A., Wan C., Denys R.V., Tsirlina G.A., Tarasov B.P., Fichtner M., Ulmer U., Yu Y., Nwakwuo C.C., Yartys V.A.
- Журнал: International Journal of Hydrogen Energy
- Том: 41
- Номер: 23
- Год издания: 2016
- Издательство: Pergamon Press Ltd.
- Местоположение издательства: United Kingdom
- Первая страница: 9954
- Последняя страница: 9967
- DOI: 10.1016/j.ijhydene.2016.01.089
- Аннотация: This work was aimed at in situ studies of the phase-structural transformations in an Mg- and Nd-modified LaNi 3 intermetallic having a bulk composition La 1.5 Nd 0.5 MgNi 9 , as related to its performance as battery anode material in the Ni-Metal Hydride batteries. The interactions in the La 1.5 Nd 0.5 MgNi 9 system were studied by in situ neutron diffraction in a temperature range 300–1248 K. Two alternative processes of preparation of the alloy were studied: (a) Synthesis from a mixture of the powders La 0.75 Nd 0.25 Ni 5 + La 0.75 Nd 0.25 MgNi 4 ; and (b) annealing of the alloy prepared by induction melting. Various transformations take place in the samples on heating, leading to the formation of four new phases, all with the stacking structures of the intermetallic alloys having three variable ratios (RE + Mg)/Ni, 1:3, 2:7 and 5:19. Further to (La 0.75 Nd 0.25 ) 2 MgNi 9 with a rhombohedral PuNi 3 type, there were formed (La 0.75 Nd 0.25 ) 3 MgNi 14 with a rhombohedral Gd 2 Co 7 structure and two polymorphic modifications of (La 0.75 Nd 0.25 ) 4 MgNi 19 compound, a high temperature hexagonal Pr 5 Co 19 type and a low temperature rhombohedral Ce 5 Co 19 type. In every case the unit cell parameters showed shrinking as compared to the La-based analogues. Nd substitution for La in La 2 MgNi 9 promotes the formation of a more homogeneous alloy, with a predominant formation of the target AB 3 intermetallic. Properly homogenized La 1.5 Nd 0.5 MgNi 9 alloy shows a more flat and longer plateau, both in the course of hydrogen absorption–desorption and under electrochemical charge–discharge. An apparent hydrogen diffusion coefficient in alloy bulk appears to be higher as compared to Nd-free alloy, contributing to a better reversibility under a high-rate operation at high discharge current densities, while maintaining a good cycle stability.
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