The electrochemical hydrogen storage performances of MgxCo100–x (x = 40, 45, 50, 55, 60, 63) body-centered cubic alloys and their Pd-doped system. (12th January 2016)

• Record Type: Journal Article
• Authors: Zhang, Yao; Zhan, Leyu; Zhuang, Xiangyang; Zhu, Yunfeng; Qu, Yi; Chen, Jian; Guo, Xinli; Wan, Neng; Li, Liquan
• Is Part Of: International journal of hydrogen energy. Volume 41:Number 2(2016)
• Page Start: 1089
• Page End: 1097
• Publication Date: 2016-01-12
• Subjects: BCC phase -- Mg–Co alloy -- Additional Pd -- Cyclic stability -- Kinetics -- Corrosion resistance; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2015.10.040
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: In this work, a serial of Mg–Co binary alloys with body-centered cubic (BCC) phase were prepared for anode materials of Ni-MH hydrogen storage battery system. TEM/SAED analyses on binary Mg–Co alloys demonstrated that their grains were all in nano-size (∼5 nm) with BCC structure. Electrochemical tests found that, with increase of the concentration of Mg in alloys, theoretical charge–discharge capacities would increase accordingly, discharge kinetics (exchange current densities and hydrogen diffusion abilities) were improved as well. However, the tested capacity will attain a maximum value (325 mAh g −1 ) at the point of Mg55 Co45 and deteriorate subsequently with continuous increase of Mg content, which was possibly due to the optimized lattice parameter value and Mg corrosion. The increase of Co concentration in the binary alloys effectively inhibited the corrosion of the electrodes. On the basis of Mg–Co binary alloys, the Pd-doped ternary alloys with BCC structure were also prepared by means of ball milling. These alloys possess greatly enhanced discharge capacities (280–500 mAh g −1 ) from binary ones. It shows that with increase of the Mg content, the discharge capacities of Mg–Co–Pd ternary alloys will increase monotonously. The additional Pd also improved cycle stabilities, kinetics, and corrosion potentials of the alloys, which was beneficial to improving the properties of Mg–Co hydrogen storage electrodes. Highlights: Binary Mgx Co100–x alloys (x = 40, 45, 50, 55, 60, 63) with BCC structure can reversibly charge–discharge in Ni-MH battery system. With the increase of Mg content in the alloys, electrodes discharge kinetics will be increased accordingly. The Pd-doped ternary alloys drastically increase the discharge capacities (280–500 mAh g −1 ) from binary ones. The additional Pd improves cycle stabilities, kinetics, and corrosion resistances of the alloys.