First investigation of indium-based electrode in Mg battery

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.