Self-supported electrodes made of LaNi4.25Al0.15Co0.5V0.1LaNi4.25Al0.15Co0.5V0.1 and Ag or Ni for hydrogenation

Shih, Ren-Jai; Su, Yu; Perng, Tsong‐Pyng

doi:10.1016/j.ijhydene.2006.01.004

Cited by 5 publications

(6 citation statements)

References 9 publications

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“…The cutoff potential was 0.9 V. The discharge capacity from this curve is 246 mAh, equal to a capacity of 512 mAh/g AB 5 , which is smaller than the capacity of the positive electrode. According to previous data, 12,14 the theoretical capacity of this pellet from the P-C-T curve is 340 mAh/g AB 5 . Therefore, this metal hydride pellet could be charged with hydrogen gas that was then used for discharge in this system.…”

Section: Resultssupporting

confidence: 66%

“…From the previous study, 13,14 it is known that both the number and size of the microholes in the pellet Ag/AB 5 = 10 are smaller than those in the pellet Ni/AB 5 = 25. The initial porosities are 3-5% and 15-18%, and the volume expansions after hydrogenation are approximately 8 and 5% for the Ag/AB 5 = 10 and Ni/AB 5 = 25 pellets, respectively.…”

Section: Resultsmentioning

confidence: 95%

“…This is much larger than the theoretical capacity of this pellet, 302 mAh/g, based on the previous P-C-T data. 12,14 At the end of this part of discharge, the positive electrode had almost run out of its capacity. A new positive electrode was replaced, and the discharge ensued immediately until the positive electrode ran out of its capacity again.…”

Section: Resultsmentioning

confidence: 98%

“…Previously, it has been reported that by careful control of the mixing ratio and sinter condition, ZrMn 0.6 V 0.2 Co 0.1 Ni 1.2 ͑AB 2 -type alloy͒ [9][10][11] and LaNi 4.25 Al 0.15 Co 0.5 V 0.1 ͑AB 5 -type alloy͒ 12 could form pellets with Ag or Ni that would maintain the integrity during repeated gas-phase and electrochemical hydriding and dehydriding. 13,14 Such pellet electrodes might have a potential application for charging in the gas phase and discharging in electrolyte. In this work, a nickel-MH battery was assembled to evaluate the performance of such a H 2 -rechargeable metal hydride electrode.…”

mentioning

confidence: 99%

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Hydrogen Gas-Rechargeable Metal Hydride Electrode for Ni-MH Battery

Shih

Perng

2005

J. Electrochem. Soc.

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Some nonbreakable pellets made of an AB 5 alloy and metallic powder Ag or Ni were used as the anode in a Ni-MH battery such that the anode could be charged in hydrogen gas and discharged in electrolyte. The performance is influenced by the alloy properties, electrode porosity, hydrogen pressure, discharge current, electrolyte polarization, and contamination in the system. For the pellet Ag/AB 5 = 10, continuous discharge can proceed but only for a limited time. The lower porosity of the pellet may be the main problem. For the pellet Ni/AB 5 = 25, it can be discharged unlimitedly at a constant hydrogen pressure of 20 atm. When discharged with a fixed amount of hydrogen gas, the adsorbed hydrogen is immediately discharged on the surface rather than being absorbed into the bulk, and the discharge capacity comes mostly from the gaseous hydrogen rather than from the hydrogen already dissolved in the bulk of alloy. Therefore, the pellet acts more like a catalyst for hydrogen dissociation than as an absorbent. Furthermore, a minimum of ϳ7 atm of hydrogen pressure is required for the system to operate properly. It is suggested that, in order for such a system to operate better under the wet condition, a higher hydrogen gas pressure be maintained to accelerate the hydrogenation rate and more porous pellets be used for faster reaction kinetics.

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Section: Resultssupporting

confidence: 66%

Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 98%

mentioning

confidence: 99%

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Hydrogen Gas-Rechargeable Metal Hydride Electrode for Ni-MH Battery

Shih

Perng

2005

J. Electrochem. Soc.

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“…[4][5][6][7][8] In previous studies, a nickel-MH battery has been assembled to evaluate the performance of a H 2 -rechargeable metal hydride battery where a nonbreakable pellet made of a AB 2 -or AB 5 -type metal hydride and Ag or Ni powder was used. [9][10][11] The metal hydride could be continuously charged by high-pressure hydrogen gas and discharged in liquid electrolyte. For the pellet Ni/AB 5 = 25, continuous discharge could be performed at a current density of 20 mA/g under a constant hydrogen pressure of 20 atm, but some side reactions may block hydrogen consumption from hydrogen gas when hydrogen gas pressure is below 7 atm.…”

mentioning

confidence: 99%

Hydrogen Gas-Rechargeable Metal Hydride Electrode for Ni-MH Battery (II)

Shih

Perng

2007

J. Electrochem. Soc.

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The present study is a follow-up of a previous work on hydrogen gas-rechargeable metal hydride ͑MH͒ electrode for Ni-MH battery. The hydrogen pressure drop in a NiOOH/H 2 battery during hydrogen absorption and electrochemical discharge was monitored. It was seen that hydrogen was simultaneously absorbed by the MH pellet electrode during discharge at higher pressures, and that the pellet released some hydrogen from the bulk when discharged at lower pressures. Electrochemical impedance spectroscopic analysis showed that the charge transfer step at the MH anode was influenced by the magnitude of hydrogen pressure. The higher hydrogen pressure resulted in a smaller semicircle and therefore a smaller charge transfer impedance.

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