Enhanced Cycling Stability of Amorphous MgNi-Based Alloy Electrodes through Corrosion Prevention by Incorporating Al 2 (SO 4) 3 ·18H 2 O into the Electrolyte.

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 Mg_0.45Ti_0.05Ni_0.50 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 Mg_0.45Ti_0.05Ni_0.50 alloy anode during charge/discharge cycling instead of Mg(OH)₂, effectively preventing further corrosion and improving its cycle life. The Mg_0.45Ti_0.05Ni_0.50 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. [ABSTRACT FROM AUTHOR]