Self-supported electrodes made of [formula omitted] and Ag or Ni for hydrogenation

Abstract

An AB 5 - type hydrogen storage alloy, LaNi 4.25 Al 0.15 Co 0.5 V 0.1 , was mixed with Ag flakes or Ni powder, pressed, and sintered to fabricate a durable pellet that would maintain its integrity during repeated gas phase or electrochemical hydriding and dehydriding. The molar compositions Ag / AB 5 ⩾ 10 and Ni / AB 5 ⩾ 25 could meet this requirement. After sintering, the alloy in the pellet Ag / AB 5 = 10 maintains the original phases, but a second phase appears in the pellet Ni / AB 5 = 25 . The volume expansions of these two pellets after hydrogenation are 5–8%. The number and size of microholes in the pellet Ni / AB 5 = 25 are larger than those in the pellet Ag / AB 5 = 10 , presumably due to different shapes of Ni powder and Ag flakes. The difference in the shape of the metallic binders also affects the discharge capacity. It is concluded that by careful control of the mixing ratio and sintering condition, the electrodes will have a potential application for charging in the gas phase and discharging in electrolyte.