Direct electrochemical preparation of CeNi sub(5) and La sub()xe sub(1-)xi sub(5) alloys from mixed oxides by SOM process

• Published in: Electrochimica acta Vol. 55; no. 8; pp. 2996 - 3001
• Main Authors: Zhao, Bingjian, Lu, Xionggang, Zhong, Qingdong, Li, Chonghe, Chen, Shuanglin
• Format: Journal Article
• Language: English
• Published: 01.03.2010
• Subjects: Alloys; Chemical composition; Electrolysis; Hydrogen storage; Mixed oxides; Nickel; Pellets; Reduction (electrolytic)
• ISSN: 0013-4686
• DOI: 10.1016/j.electacta.2010.01.008

A novel SOM process was used to prepare CeNi sub(5) and La sub()xe sub(1-)xi sub(5) hydrogen storage alloys directly from their mixed oxides. The electrolytic reduction was carried out in molten CaCl sub(2) system at 1000 degree C. The reduction mechanism was investigated by analyzing the chemical compositions and the phase constitutions of the intermediate products of electrolysis. The results suggested that the reduction of NiO-CeO sub(2) may take place in two steps: first, NiO was reduced into Ni and CeO sub(2) reacted with CaCl sub(2) to form CeOCl, then Ni reacted with CeOCl leading to the formation of CeNi sub(5). It was found that the reduction rate increased while decreasing the pressure load of the mixed oxide pellets. Furthermore, CeNi sub(5) could not be produced if the pressure load was lower than 10 MPa. It was also found that the pellets of NiO-CeO sub(2) could be completely reduced to CeNi sub(5) alloy by the SOM process, which was greatly excelled than FFC process. The successful preparation of La sub()xe sub(1-)xi sub(5) (x = 0-1) alloy reported here suggests that the SOM process may be promising for the industrial application of producing such alloys.