Electrochemical Utilization of Metal Hydrides

Bittner, H. F.; Badcock, C. C.

doi:10.1149/1.2119925

Cited by 100 publications

(24 citation statements)

References 11 publications

(28 reference statements)

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“…For practical electrochemical devices, metal hydrides are sought with the following properties: high capacity to store hydrogen, low hydrogen equilibrium pressure, high rates of absorption and desorption, long cycle life, low cost, light weight, and corrosion resistance.1 Although some of these properties have been achieved by the optimization of alloy composition for stability and hydrogen reversibility, challenges remain in the form of capacity decay and corrosion resistance for the development of an efficient NiOOH-metal hydride (Ni-MH) cell. 2 Capacity decay arises because of alloy pulverization and subsequent oxidation of the hydride surface during repeated charge-discharge cycles. During cycling of the electrodes, precipitates of metals are produced at the surface by segregation and decomposition3'4 of active material.…”

Section: Infroductionmentioning

confidence: 99%

Studies on Electroless Cobalt Coatings for Microencapsulation of Hydrogen Storage Alloys

Haran

Popov

White

1998

J. Electrochem. Soc.

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LaNi4 275n,24 alloy was microencapsulated with cobalt by electroless deposition from an alkaline hypophosphite bath. Discharge curves of the encapsulated alloy indicate an additional contribution to the capacity arising from the cobalt on the surface. Studies on cobalt thin films reveal the presence of adsorbed hydrogen in cobalt. The amount of hydrogen adsorbed was observed to increase with time of cathodic polarization and to reach a maximum. Polarization techniques have been used to characterize the cobalt-plated alloy as a function of state of charge. The equilibrium potential of the microencapsulated electrode at low hydrogen concentration is determined by the potential of the cobalt coating on the surface. InfroductionNickel hydride batteries (MH) with reversible hydrogen storage alloys have recently attracted great attention. For Recently, we studied the shape evolution of copper bumps with photoresist angles.9This investigation discusses the cavity shapes and the current distributions for deep cavities. The role of convection and diffusion within the cavities is discussed. The current distributions at diffusion limited overpotentials were calculated by the numerical fluid dynamics computations.

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Section: Infroductionmentioning

confidence: 99%

Studies on Electroless Cobalt Coatings for Microencapsulation of Hydrogen Storage Alloys

Haran

Popov

White

1998

J. Electrochem. Soc.

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“…2 that higher A1 content of the alloy produces higher specific capacity. The low specific capacity of the LaNi, electrode at ambient pressure is mainly due to its inherent nature, which would require a hizh hydrogen pressure to achieve a higher x value [4]. The effect of higher AI concentrations on the cell performance improvement can be partly explained by the lowered hydrogen equilibrium pressure requirement of the Alcontaining alloys [5].…”

Section: Resultsmentioning

confidence: 99%

Electrochemical and In Situ Neutron Diffraction Investigations of La‐Ni‐Al‐H Alloys

Redey

Jansen

et al. 1997

J. Electrochem. Soc.

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The submitted manuscript has been authored by e wntractor of the US. Government under rmbed No. W-31-109ENG-38. Accordingly, me U. S. oovemment retains a nonercluslve, rcyaay. baa Wnse to publish or reprodwe the pubhhed form of this wntribulion, or allow others to do so, tor u. s. Govemmem purposes. May 5-1 0,1996To be presented at the Spring Meeting of The Electrochemical Society, Inc., Los Angeles, California May [5][6][7][8][9][10]1996 'Illinois Institute of Technology DISCLAIMERPortions of this document may be illegible in electronic image products. Images are produced from the best available original document. ELECTROCHEMICAL AND IN SITU NEUTRON DIFFRACTION INVESTIGATIONS OF La-Ni-A1-H ALLOYS IntroductionThe nickel/metal hydride (Ni/MH) battery is a strong contender to replace the nickekadmium battery because of its superior performance, low impedance, and absence of toxic cadmium. However. the present NiMH battery is limited by hydrogen management problems associated with chargddischarge operation and self-discharge of the battery and by long-term capacity loss due to corrosion of the MH electrode. Rare earth metal-based alloys such as M i , , preferably with the partial substitution of lanthanum or nickel by a small amount of other metal elements, seem to be promising MH materials to improve the stability and capacity of the MH electrodes. However, the role of alloying components is not yet clearly understood. Therefore, a combination of electrochemical and neutron diffraction techniques has been designed to investigate metal hydrides. This combination of the surface and bulk investigation techniques provides a unique tool to study the properties of the alloy electrodes in situ with respect to composition, atomic structure, and phase change [ 1-31. In this work, several AI-substituted LaNi, alloys were investigated with respect to their specific capacity (measured by mAh/La and symbolized by x in LaNi,$l,,H,), impedance, and cycling stability. In addition to the extensive electrochemical investigations, in situ neutron diffraction measurements were performed to characterize the electrochemically induced phase transformation and structure change during charge and discharge of the metal hydride electrodes. ExperimentalThe following simple cell reaction permits simple cell construction.The electrochemical testing was carried out in a threeelectrode cell consisting of a commercial NiO(0H) positive electrode. a Hg/HgO reference electrode with electrolyte bridge and Luggin capillw. a metal-hydride electrode. and I 5 9 KOH electrolyte. Teflon mesh separator was used between the working and counter electrodes. The alloy powder (Rhone-Poulenc, -400 mesh size) was mixed with 5 8 carbon (Shawinigan Black) conducting additive and I O 9 DuPont Teflon 30 suspension and pressed onto an expanded nickel mesh to form I-mm-thick electrodes.To investigate the electrochemical performance of the metal hydride electrode. plane-parallel or jelly-roll electrode combinations were used to ensure uniform current density. The f...

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“…A PSS is obtained by assuming that at a particular time, for a particular value of the shrinking core radius, x c , the concentration profiles 3 Assumed Substituting this solution into Eq. 13 followed by integration yields [32] which is plotted in Fig.…”

Section: Pseudosteady-state Solution (Pss)mentioning

confidence: 99%

“…Metal hydride particles are used to make negative electrodes [1][2][3] in nickel/metal hydride batteries. The performance of these electrodes is affected by both the kinetics of the processes occurring at the metalelectrolyte interface and the hydrogen diffusion within the bulk of the metal alloy particle.…”

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confidence: 99%