Direct Electrolysis Process of Hydrogen absorbing alloy films from Molten Salts and Film Characterization

氢吸收。HAA合金由元素A （La、Mg、Ca、Ti等）和元素B （Ni、Fe、Cu等）组成。A元素通常是非常活跃的金属，在熔盐中电沉积在基底B上，并相互扩散制成具有吸氢性能的金属间化合物。这种生产HAA的工艺具有直接从活性元素A和膜型资源中生产的优势。采用氯化物镀液在镍基体上电沉积镧。在衬底上形成的相取决于电解条件，如温度、电流密度、电解时间等。通过控制电解条件，可以得到HAA薄膜LaNi_5。用电化学方法在碱性溶液中测定了HAA薄膜的充放电性能。在1023 K下，在0.1 Acm^<-2>的电流密度下，在0.4 ks的时间内，Ni衬底上形成了25 μm的LaNi_5层。该膜对氢气的吸附/解吸性能优于商品LaNi5钢锭。在充放电过程中，Ni衬底抑制了表面HAA薄膜的脆化。另一方面，La和Co在Ni片上共电沉积得到LaNi_<5-x>Co_x （X<1%）层。Co的加入也改善了循环性能。

Hydrogen absorbing. alloy, HAA, consists of element A (La, Mg, Ca, Ti, etc) and element B (Ni, Fe, Cu, etc). The elements A, which are generally very active metals, were electrodeposited on substrate B in molten salts and diffused each other to make intermetallic compounds with hydrogen absorbing property. This process for HAA production has an advantage to produce directly from resources of active element A and film type.Lanthanum was electrodeposited on nickel substrate in chloride bath. The phase formed on the substrate depends on electrolysis conditions such as temperature, current density, electrolysis duration, etc. The HAA film, LaNi_5, can be obtained by controlling the electrolysis condition. The charge-discharge property for the HAA films were estimated electrochemically in an alkaline solution at ambient temperature. In La electrolysis, LaNi_5 layer with 25 μm formed on Ni substrate during 0.4 ks under the current density of 0.1 Acm^<-2> at 1023 K.This film showed better cyclic charge-discharge property for hydrogen adsorption/disorption than commercial LaNi5 ingot. The Ni substrate inhibited the embrittlement of HAA film on the surface during charge-discharge test. On the other hand, co-electrodeposition of La and Co on Ni sheet gave LaNi_<5-x>Co_x (X<1%) layer. This Co addition also improved cyclic property.