Enhanced Cycling Stability of Amorphous MgNi-Based Alloy Electrodes through Corrosion Prevention by Incorporating Al2(SO4)3·18H2O into the Electrolyte

• Published in: Metals (Basel ) 2024-10, Vol.14 (10), p.1142
• Main Authors: Li, Jiabao, Cai, Yang, Huang, Jianling, Zhao, Shiqian, Cheng, Deliang
• Format: Article
• Language: English
• Subjects: Alloys; Aluminum sulfate; Amorphous alloys; Amorphous materials; Anodes; corrosion; Corrosion potential; Corrosion prevention; cycle life; Cycles; Discharge; Electric vehicles; Electrode materials; Electrodes; Electrolytes; Hydrogen storage; Magnesium base alloys; Metal hydrides; Mg-based alloys; Ni-MH battery; Reproducibility; Stability
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met14101142

Mg-based alloy anodes suffer from severe corrosion in alkaline electrolytes, which substantially impedes their cycle life and thereby limits their suitability as anode materials for nickel–metal hydride (Ni-MH) batteries. This work modifies the conventional 6 M KOH electrolyte by adding 0.1 M Al2(SO4)3·18H2O. The electrochemical hydrogen storage properties of Mg0.45Ti0.05Ni0.50 alloy in this electrolyte and its microstructural evolution during cycling are studied. In the 6 M KOH + 0.1 M Al2(SO4)3·18H2O electrolyte, a protective layer consisting of Mg2Al(OH)7 is formed on the surface of the Mg0.45Ti0.05Ni0.50 alloy anode during charge/discharge cycling instead of Mg(OH)2, effectively preventing further corrosion and improving its cycle life. The Mg0.45Ti0.05Ni0.50 alloy anode delivers a maximum discharge capacity of 479.0 mAh g−1 and maintains 318.4 mAh g−1 after 30 cycles in the 6 M KOH + 0.1 M Al2(SO4)3·18H2O electrolyte, which is significantly superior to that achieved in the 6 M KOH electrolyte (471.1 mAh g−1 and 201.8 mAh g−1, respectively). This work provides a new strategy for improving the cycle stability of Mg-based alloy anodes.