LaNi_5系合金のプロチウム吸蔵特性および電気化学特性に及ぼす化学的エッチングの影響 Effect of Chemical Etching on Protium Absorbing Properties and Electrochemical Characteristics of LaNi_5 Alloys
When hydrogen storage alloy is used as a negative electrode of nickel-metal hydride batteries, protium absorbing properties at a negative electrode is different from those at a gas phase because of the formation of oxide layers and a nickel-rich layer on the surface of the alloy due to charge and discharge. This paper investigates the effect of surface chemical etching on protium absorbing properties and electrochemical characteristics of LaNi<SUB>5</SUB> alloys. Dilute HCI solution under 1% was used as etchants for the formation of a nickel-rich layer which works as a protection surface of the alloy against the KOH electrolyte. Protium absorbing properties of annealed LaNi<SUB>5</SUB> samples which were etched shortly with 0.2N HCl or 0.02N HCl were better protium storage capacity than those of unetched annealed LaNi<SUB>5</SUB> samples. Electrochemical characteristics of annealed LaNi<SUB>5</SUB> samples which were etched for 60min with 0.02N HCl were better cycle stability than those of unetched annealed LaNi<SUB>5</SUB> samples.
粉体および粉末冶金 46(2), 131-137, 1999-02-15
Japan Society of Powder and Powder Metallurgy