Effect of Sn substitution for Co on microstructure and electrochemical performance of AB5 type La0.7Mg0.3Al0.3Mn0.4Co0.5−xSnxNi3.8 (x =0−0.5) alloys

Authors

Julio Cesar Serafim Casini, University of Wollongong
Zaiping Guo, University of WollongongFollow
Hua-Kun Liu, University of WollongongFollow
Eliner Affonso Ferreira, University of Sao Paulo
Rubens Nunes Faria, University of Sao Paulo
Hidetoshi Takiishi, University of Sao Paulo

RIS ID

98456

Publication Details

Casini, J., Guo, Z., Liu, H. Kun., Ferreira, E., Faria, R. & Takiishi, H. (2015). Effect of Sn substitution for Co on microstructure and electrochemical performance of AB₅ type La_0.7Mg_0.3Al_0.3Mn_0.4Co_{0.5 − x}Sn_xNi_3.8 ( x =0−0.5) alloys. Nonferrous Metals Society of China Transactions, 25 (2), 520-526.

Abstract

The effects of substitution of Sn for Co on the microstructure, hydrogen storage and electrochemical discharge capacity of La_0.7Mg_0.3Al_0.3Mn_0.4Co_{0.5 − x}Sn_xNi_3.8 (x=0, 0.1, 0.2, 0.3 and 0.5) alloys were investigated using X-ray diffraction (XRD), pressure composition isotherm (PCT) and electrochemical discharge cycle. XRD, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) tests showed that all of alloys are mainly composed of LaNi₅ and MgNi₂ phases, but when increasing the content of Sn in alloys, the LaNiSn phase appears and microstructure is refined. The PCT showed that increasing substitution of Sn for Co results in decrease of the maximum hydrogen storage capacity from 1.48% (x=0) to 0.85% (x=0.5). The electrochemical tests indicated that the maximum discharge capacity decreases from 337.1 mA·h/g (x=0) to 239.8 mA·h/g (x=0.5); however, the discharge capacity retention at the 100th cycle increases from 70.2% (x=0) to 78.0% (x=0.5).