Electrodes metal-hydride

Flanagan and Oates [1] have extensively reviewed the thermodynamics of intermet-allic hydrides also recommended are the classic work of Libowitz [2] and the com- 

It is essentially a phase diagram which consists of a family of isotherms that relate the equilibrium pressure of hydrogen to the H content of the metal. Initially the isotherm ascends steeply as hydrogen dissolves in the metal to form a solid solution, which by convention is designated as the a phase. At low concentrations the behaviour is ideal and the isotherm obeys Sievert s Law, i.e., 

Thermodynamic quantities for a system may be determined from the van t Hoff equation Eq.(3), which defines the equilibrium constant, K, in terms of the reaction enthalpy, AH and the temperature, T. 

The enthalpy of the phase conversion can be determined from Eq.(6) by plotting the log of the absorption or desorption plateau pressure, Ppiaieau against the reciprocal temperature as indicated in Fig. 2. When the solubility of hydrogen in the metal (or) phase is small, then A// A//,-, where A//f is essentially the enthalpy of forma 

Many metals and alloys reversibly absorb large quantities of hydrogen to form metal hydride (MH) phases, and for many years the focus of MH research was 

Handbook of Battery Materials, Second Edition. Edited by Claus Daniel and Jurgen O. Besenhard. 

Under ideal conditions the activity of a solid may be taken as unity and the fugacity as the pressure, then Equation 9.3 may be rewritten as 

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H. Ogawa, M. Ikoma, H. Kawano, and I. Matsumoto, "Metal Hydride Electrode for High Energy Density Sealed Nickel—Metal Hydride Battery," Proceedings of the 16th International Power Sources Conference, UK, 1988. 

There are few systematic guidelines which can be used to predict the properties of AB2 metal hydride electrodes. Alloy formulation is primarily an empirical process where the composition is designed to provide a bulk hydride-forming phase (or phases) which form, in situ, a corrosion— resistance surface of semipassivating oxide (hydroxide) layers. Lattice expansion is usually reduced relative to the ABS hydrides because of a lower VH. Pressure-composition isotherms of complex AB2 electrode materials indicate nonideal behaviour. 

Zheng G., Popov B.N. and White R. E. Application of Porous Electrode Theory on Metal-Hydride Electrodes in Alkaline Solution. J. Electrochem Soc. 1996 143 435-41. 

Wasz, M.L., R.B. Schwarz, S. Srinivasan, and M.P.S. Kumar, Sn-substituted LaNi5 alloys for metal hydride electrodes, Mater. Res. Soc. Symp. Proc., 393, 237-242,1995. 

Governed by Laplace s Equation Metal Hydride Electrodes 27... 

Fig. 6.11 Six-cell nickel-meial hydride batiery. 1. positive cap, connected to the nickel oxide electrode 2, can, connected to metal hydride electrode and serving as negative terminal 3. separator 4. cathode 5, anode 6. plastic battery case which contains interconnected cells and electronic management system. (By permission of Duracell.)...

Keywords hydrogen absorption, composite alloys, metal hydride electrodes, hydrogen spillover... 

The common assumption is that the electrochemical performance of metal hydride electrodes is strongly influenced by the additions to hydride forming alloy,... 

Vaivars G., Kleperis J., Mlynarek G., Wojcik G., Zavaliy I. (1999) The ac Impedance Behaviour of the Ti4Ni20y and Ti3.5Zr0.5Ni2Oy Type Metal Hydride Electrodes, Ionic s 5, 3-4, 292-298. 

Lundqvist A. (1998) The Metal Hydride Electrode and the Nickel Metal Hydride Battery, Licentiate thesis... 

INVESTIGATION OF A NOVEL METAL HYDRIDE ELECTRODE FOR Ni-MH BATTERIES... 

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