Abstract
Micrometric indium powder was investigated for the first time as active material for Mg battery negative electrodes using Mg-organohaloaluminate electrolyte. Indium electrochemically alloys with Mg to form the intermetallic compound MgIn. The alloying reaction is highly reversible. At low cycling rate, a high capacity of 425 mAh g− 1 is achieved, with the lowest alloying potential ever reported vs. Mg. The investigation of the electrochemical mechanism by operando x-ray diffraction confirmed a biphasic transition from In to MgIn in agreement with the Mg–In phase diagram, and without any intermediate amorphization process. High and stable capacity is observed by cycling at low rates, whereas rate-capability tests evidenced a rapid fading upon high current densities. Micrometric intermetallic MgIn directly synthesized by high-energy ball milling was also investigated and exhibited similar electrochemical behavior. These results confirm the interest of p-block elements as possible negative electrode materials for Mg batteries.