Crystallographic and Electrochemical Hydrogen Storage Performances of La0.75Ce0.25Ni3.80Mn0.90Cu0.30(Fe0.43B0.57)x (x = 00.20) Alloys

• Published in: International journal of electrochemical science 2014-09, Vol.9 (9), p.4913-4924
• Main Authors: Shang, Xianguang, Lu, Shan, Peng, Xianyun, Fan, Yanping, Zhang, Baoqing, Zhang, Zhi, Liu, Baozhong
• Format: Article
• Language: English
• Subjects: Electrochemical hydrogen storage performances; Electrochemical properties; Microstructures; Nickel/metal hydride battery; X-ray diffraction
• ISSN: 1452-3981; 1452-3981
• DOI: 10.1016/S1452-3981(23)08141-5

Herein, a hyper-stoichiometry Fe0.43B0.57 addition was used to improve the electrochemical hydrogen storage characteristics of Co-free high-Mn alloy. Microstructures and electrochemical performances of La0.75Ce0.25Ni3.80Mn0.90Cu0.30(Fe0.43B0.57)x (x = 0-0.20) alloys are investigated. X-ray diffraction and backscattered electron results indicate that the pristine alloy is LaNi5 phase, while the alloys containing Fe0.43B0.57 consist of LaNi5 matrix phase and La3Ni13B2 secondary phase. The relative abundance of La3Ni13B2 phase increases, and the a, c and V of LaNi5 phase decrease with increasing x value. Maximum discharge capacity of the alloy electrodes monotonically decreases from 329.1 mAh/g (x = 0) to 314.7 mAh/g (x = 0.20). High-rate dischargeability of the alloy electrodes first increases with increasing x from 0 to 0.10, and then decreases until x increases to 0.20. Cycling capacity retention rate at the 100th cycle increases from 51.1% (x = 0) to 72.2% (x = 0.20) with increasing x value, which is ascribed to the improvement in pulverization resistance. It is demonstrated that the addition of Fe0.43B0.57 is an effective approach to improve the comprehensive electrochemical performances of Cofree high-Mn alloy electrodes.