Gaseous and electrochemical properties of Laves type Ti-Zr alloys with enhanced H storage capacity and advanced performance as metal hydride battery anodes

Ika Dewi Wijayanti^1,2,3, Roman Denys¹, Suwarno³, M.V. Lototsky⁴, Volodymyr Yartys¹

¹ Institute for Energy Technology, Kjeller, Norway; ² Norwegian University of Science and Technology, Trondheim, Norway; ³ Sepuluh Nopember Institute of Technology, Indonesia; ⁴ University of the Western Cape, South Africa

AB_2-xLa_0.03 Laves type alloys (A=Ti_0.15Zr_0.85; B=Mn_0.64–0.69V_0.11–0.119Fe_0.11–0.119Ni_{1.097–1.184}; x = 0, 0.05 and 0.1) were prepared by arc melting and annealed resulting in their homogenization. The variation of chemical composition of the alloys by changing the ratio between A (Ti+Zr) and B (Mn+V+Fe+Ni) components has been studied to optimize hydrogen storage and electrochemical behaviors as anodes of the metal hydride batteries. The studies involved probing of the phase-structural composition by X Ray diffraction and neutron scattering, together with studies of the microstructural state, hydrogen absorption–desorption and thermodynamic characteristics in gas–solid reactions, and in the electrochemical charge-discharge and impedance spectroscopy tests. Furthermore, Rapid Solidification has been applied to study an interrelation between the nanostructuring achieved during their melt casting and their performance as H storage and battery anode materials.

The annealed alloys were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and XRD, which concluded that the main C15 FCC Laves type AB₂ compound co-exists with a minor C14 hexagonal Laves phase. The gaseous capacity and electrochemical performances were found to be closely related to the stoichiometry changes of the alloys. High discharge capacities approaching 500 mAh∙g^─1 were achieved for the annealed AB_1.95 alloy. Moreover, studies of hydrogen diffusion showed that annealing enhances the hydrogen diffusion rates allowing advanced performance at high discharge current densities. This has been related to a higher content of C15 Laves compound which allows to reach a higher H mobility in contrast with higher storage capacity observed for the C14 Laves type polymorph.

Results of the work were published in the following publications [1,2].

1. Ika Dewi Wijayanti, Live Mølmen, Roman V. Denys, Jean Nei, Stephane Gorsse, Kwo Young, Matylda N. Guzik, and Volodymyr Yartys.The electrochemical performance of melt-spun C14-Laves type Ti-Zr-based alloy.// International Journal of Hydrogen Energy. In press (March 2019).  https://doi.org/10.1016/j.ijhygene.2019.02.093
2. Alexei A. Volodin, Roman V. Denys, ChuBin Wan, Ika Dewi Wijayanti, Suwarno, Boris P. Tarasov, Vladimir E. Antonov and Volodymyr A. Yartys. Study of Hydrogen Storage and Electrochemical Properties of the AB₂-type Ti₁₅Zr_0.85La_0.03Ni_1.2Mn_0.7V_0.12Fe_0.12 alloy.// Journal of Alloys and Compounds. Published online 8 March 2019.