Synthesis of La2 Ni1 xCox 7 x 0 05 0 1 0 2 Hydrogen Storage Alloys by the Electro Deoxidation Technique

OpenAlex İngilizce

La 2 (Ni 1-x Co x ) 7 (x = 0.05, 0.1, 0.2) alloys were synthesized directly from sintered mixture of La 2 O 3 + NiO + CoO in the molten CaCl 2 electrolyte by the electro-deoxidation method at 850°C and the electrochemical hydrogen storage characteristics of the synthesized alloys were observed. Sintering (at 1200°C for 3 h) converted the hygroscopic La 2 O 3 (by the reaction with NiO) into the non-hygroscopic LaNiO 3 , La 3 Ni 2 O 6.5 and La 4 Ni 3 O 9 depending on the Co content of the oxide mixture. The X-ray diffraction peaks indicated that La 2 NiO 4 was the main La-Ni-O phase formed as a result of partial reduction or dissociation reaction to initiate the LaNi 5 phase formation. The target La 2 Ni 7 phase formed much later than LaNi 5 phase probably due to the sluggish reduction of LaOCl. It was observed that La 2 (Ni 1-x Co x ) 7 (x = 0.05, 0.1, 0.2) alloys had promising discharge capacities changed between 227 mA h g −1 (La 2 (Ni 0.95 Co 0.05 ) 7 ) and 332 mA h g −1 (La 2 (Ni 0.8 Co 0.2 ) 7 ) depending on the alloy Co content. This work clearly indicated that the electro-deoxidation was very effective method in the synthesis of the hydrogen storage materials.