Microstructure and electrochemical hydrogen storage characteristics of La0.67Mg0.33−xCaxNi2.75Co0.25 (x = 0–0.15) electrode alloys

✍ Scribed by Zhenwei Dong; Yaoming Wu; Liqun Ma; Lidong Wang; Xiaodong Shen; Limin Wang

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 651 KB
• Volume: 36
• Category: Article
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2010.12.008

✦ Synopsis

The microstructure and electrochemical hydrogen storage characteristics of La 0.67 Mg 0.33Àx Ca x Ni 2.75 Co 0.25 (x ¼ 0, 0.05, 0.10 and 0.15) alloys are investigated. The results show that all alloys mainly consist of (La, Mg)Ni 3 and LaNi 5 phases, besides a small amount of (La, Mg) 2 Ni 7 phase.

The cycle stability (S 80 ) after 80 charge/discharge cycles of all alloy electrodes first increases from 60.1% (x ¼ 0) to 64.2% (x ¼ 0.05), then decreases to 45.9% (x ¼ 0.15). The high rate dischargeability of all alloy electrodes first increases from 52.6% (x ¼ 0) to 61.4% (x ¼ 0.10), then decreases to 57.2% (x ¼ 0.15). Moreover, the charge-transfer resistance (R ct ) first decreases from 168.2 mU (x ¼ 0) to 125.7 mU (x ¼ 0.10), then increases to 136.6 mU (x ¼ 0.15). All the results indicate that the substitution of Mg with a certain amount of Ca can improve the overall electrochemical characteristics.