Alloys to Replace Mg Anodes in Efficient and Practical Mg-Ion/Sulfur Batteries

The development of rechargeable Mg/S batteries is driven by the design of reliable electrolytes. To date, they seem not suitable for industrial transfer as they are either corrosive or necessitate a complex formulation. The innovative strategy reported here, which replaces magnesium by Mg alloys at the negative electrode, enables employing facile electrolyte formulations as well as proposes an easier electrode-shaping process. As a proof-of-concept, Mg3Bi2/S cells were evaluated with simple Mg(TFSI)2/DME electrolyte. Electrochemical mechanisms including Mg3Bi2 dealloying and sulfur magnesiation were probed by X-ray diffraction and X-ray photoelectron spectrocsopy, respectively. In addition, very promising cycling performance at elevated current density is obtained. These preliminary findings pave the way for additional improvements toward further practical applications.