Dischargeability Of Alloy Electrodes Research Articles

Effect of Li on structure and electrochemical hydrogen storage properties of Ti55V10Ni35 quasicrystal alloy

The Ti55V10Ni35 quasicrystal ribbons are synthesized by arc melting and subsequent melt-spinning technique and then Li atoms are infiltrated into this quasicrystal material by the way of electroosmosis. X-ray diffraction results indicate that the pristine quasicrystal Ti55V10Ni35 mainly consists of the icosahedral quasicrystal (I-phase), V-based solid solution phase with BBC structure and face centered cubic (FCC) phase with Ti2Ni-type structure. After infiltrating some amount of Li atoms into Ti55V10Ni35 quasicrystal lattice voids at different electroosmosis current density (A/mg) of 0.3, 0.6 and 0.9 respectively, phase structure investigations show that the main phase structures do not change greatly except for the additional lithium phase, which demonstrates that Li does not destroy the phase structure of Ti55V10Ni35 quasicrystal. Ti55V10Ni35 alloy shows the best discharge capacity is 219.8 mAh g−1 at a current density of 30 mA g−1. The negative electrode made by Ti55V10Ni35–Li quasicrystal alloys (Li atoms are infiltrated into Ti55V10Ni35 quasicrystal alloy at different the electroosmosis current density (A/mg) of 0.3, 0.6 and 0.9 has a maximum discharge capacity of 257.7 mAh g−1, 301.8 mAh g−1 and 238.7 mAh g−1 at a discharge current density of 30 mA g−1, respectively. And the high rate discharge ability of alloy electrodes is higher than that of Ti55V10Ni35 quasicrystal alloy at 240 mA g−1. The Effect of Li on structure of Ti55V10Ni35 quasicrystal has been discussed by measuring the place, mass ratio and chemical state that Li infiltrated into quasicrystal Ti55V10Ni35 lattice. In addition, the electrochemical reaction kinetics of Ti55V10Ni35–Li quasicrystal alloy electrodes is also studied by measuring both the electrochemical impedance spectroscopy and hydrogen diffusion coefficient.

A study on structure and electrochemical properties of (La, Ce, Pr, Nd)2MgNi9 hydrogen storage electrode alloys

Abstract (La, Ce, Pr, Nd) 2 MgNi 9 hydrogen storage alloys were prepared through induction melting followed by a long annealing treatment. The structure and electrochemical properties of annealed alloys have been investigated by orthogonal design experiments. Both the individual effects of each substituting element and their interaction in alloys were studied systemically. It has been shown that the structure of main phase in alloys belongs to PuNi 3 -type with a space group R -3 m . Substituting rare-earth elements have a significant effect on both the phase structure of alloys and microstructure. The anisotropic change in the crystal structure of alloys can cause the acceleration of pulverization of alloy particles and result in the deterioration of the cyclic stability of alloy electrodes. Misch metals can raise the plateau pressure of hydrogen absorption/desorption. The discharge capacity of alloy ranges from 342.97 to 380.68 mAh g −1 depending on the sort and content of substituting elements. Both cerium and neodymium can obviously reduce the discharge capacity of alloy electrodes. When compared to the La 2 MgNi 9 alloy electrode, mish metals can significantly improve the high rate dischargeability of alloy electrodes. The improvement of the kinetic characteristic of alloy electrodes mainly results from the increase of the hydrogen diffusion rate in alloy bulk.