Phase Structure, Electrochemical Properties and Cyclic Characteristic of a Rhombohedral-Type Single-Phase Nd2MgNi9 Hydrogen Storage Alloy. Issue 7 (1st January 2016)

• Record Type: Journal Article
• Authors: Du, Wenkai; Zhang, Lu; Li, Yuan; Zhao, Yumeng; Yang, Shuqin; Liu, Baozhong; Han, Shumin
• Is Part Of: Journal of the Electrochemical Society. Volume 163:Issue 7(2016)
• Page Start: A1474
• Page End: A1483
• Publication Date: 2016-01-01
• Subjects: Electrochemical property -- Hydrogen storage alloy -- Neodymium-magnesium-nickel-based alloy -- Rhombohedral-type structure -- Single phase; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0111608jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : A single-phase PuNi3 -type Nd2 MgNi9 alloy was firstly prepared through induction melting followed by zoning annealing method, and the structural and electrochemical properties of the alloy were studied. Low-angle X-ray diffraction and Rietveld refinement analyses verify that the crystal structure of the Nd2 MgNi9 alloy is the PuNi3 -type super-stacking structure with a space group R -3m. It is found that the Nd2 MgNi9 alloy electrode exhibits excellent electrochemical properties. The discharge capacity of the alloy electrode is 370.6 mAh g −1 and its high rate dischargeability reaches up to 49.6% at a 1440 mA g −1 discharge current density. Especially, the cyclic stability is heightened to 92.1% at the 100 th charge/discharge cycle and retains 79% at the 300 th charge/discharge cycle, which are significantly better than those of the PuNi3 -type La2 MgNi9 alloy. On the basis of the R -3m crystal structure calculation results, we found that the single-phase Nd2 MgNi9 alloy has the smaller volume deformation rate Δ V / V (+1.19%) and lower lattice strain (0.3180(3)%) after hydrogenation/dehydrogenation, resulting in the weaker pulverization degree of the alloy particle and minor oxidization/corrosion of active material.