Modeling of Electrochemical Hydrogen Storage in Metal Hydride Electrodes

Abstract

The recently presented electrochemical kinetic model, describing the electrochemical hydrogen storage in hydride-forming materials, was extended by the description of the solid/electrolyte interface, i.e., the charge-transfer kinetics and electrical double-layer charging. A complete set of equations was derived, describing the equilibrium hydrogen partial pressure, the equilibrium electrode potential, the exchange current density, and the electrical double-layer capacitance as a function of hydrogen content in both solid-solution and two-phase coexistence regions. The model was applied to simulate isotherms of Pd thin films with nominal thicknesses of 200 and 10 nm. The model demonstrates good agreement between the simulation results and experimental data.

Physics of Hydrogen

“…A Pd electrode is electrochemically hydrogenated under galvanostatic conditions at 25°C [85]. Qualitatively, one obtains the same course for the hydrogen activity isotherms as for the hydrogen pressure isotherms in the case of a direct (thermally activated) reaction of the elements (Figure 24.15) [72].…”

“…In a second step the adsorbed H-atoms are incorporated into the metal and diffuse into the bulk metal: The recombination of adsorbed H (Tafel reaction) or the dehydrogenation of water (Heyrovski reaction) leads to the formation of molecular hydrogen [84]. This is regarded as a side reaction: The electrode reaction can be described by Butler-Volmer kinetics [85]. The exchange current density reflects the capability of the utilized material to adsorb and incorporate hydrogen, as well as the kinetics of the side reactions [72].…”

“…16 Equilibrium potential and derived equilibrium hydrogen pressure for the electrochemical hydrogenation of a 200 nm PdH x electrode at 25°C[85].…”

Highly Porous Carbon from Microalga, Chlorella Vulgaris, as an Electrochemical Hydrogen Storage Material

“…1 Among techniques of hydrogen storage, the most encouraging technique is electrochemical hydrogen storage, because this approach could be performed at the ambient temperature and low pressure via a simple apparatus. [2][3][4][5][6][7][8][9][10][11][12][13] It must be emphasized that the adsorption/desorption of hydrogen in electrochemical hydrogen storage takes place in the room temperatures and the ambient pressure that is very different via systems, which operate in cryogenic condition and high pressure.…”

Influence of Different Electrolyte Concentrations on the Performance of an AB2-Type Alloy

“…The global rechargeable battery market is expected to exhibit strong growth in the next years, due to their use in large amount and diversity of portable electronic devices, electric and hybrids vehicles, toys, robots, etc. [1][2][3][4][5][6][7] Nickel-metal hydride (Ni-MH) batteries belongs to this kind of accumulators. Ni-MH batteries have been extensively studied owing to their high capacities, fast charge and discharge capabilities, environment-friendly features and long cycle life.…”