A scientific study of current collectors for Mg batteries in Mg(AlCl ₂EtBu)₂/THF electrolyte

The electrochemical behavior and stability of several current collectors (copper, nickel, stainless steel 316L, aluminum, titanium) potentially employed in magnesium batteries with non-aqueous Mg(AlCl₂EtBu)₂/THF electrolyte have been investigated in both three-electrode electrochemical cell and coin cell configurations. Linear sweep voltammetry and coin cell charge/discharge measurements indicate that copper, widely used in the literature as a current collector in this electrolyte, is not stable and undergoes pitting corrosion above ̃1.8 V. Cyclic voltammetry shows that copper undergoes electrochemical oxidation and reduction in the electrolyte, which was further confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) analyses. Among the current collectors studied, nickel shows excellent electrochemical stability up to ̃2.2 V and high efficiency for magnesium deposition and dissolution processes in the electrolyte, indicating that it is a strong candidate as both cathode and anode current collectors in magnesium batteries.