Rapid preparation of high-performance Mg2Sn thermoelectric materials and their unique role in metal-air batteries

Abstract

Magnesium-air batteries hold potential applications due to their high energy density and environmental friendliness. However, the formation of passivation films and the suboptimal standard electrode potential have been primary scientific challenges hindering the rapid advancement of magnesium-air batteries. This study develops Mg2Sn anode materials and conceptualizes a mechanism leveraging their superior thermoelectric properties to enhance the open-circuit voltage and inhibit the formation of passivation films. By employing a self-designed magnesium saturation temperature smelting method, high-performance n-type and p-type Mg2Sn thermoelectric materials are synthesized rapidly in the air. Notably, the n-type thermoelectric material exhibits a peak power factor of up to 4.83 mW m−1 K−2 and a thermoelectric figure of merit (ZT) exceeding 1. A unique Mg2Sn-air battery is engineered to utilize thermoelectric effects for modulating the built-in electric field. This design not only compensates for the open-circuit voltage but also harnesses the Seebeck electromotive force generated by Mg2Sn to suppress the formation of passivation films on the anode surface, giving the high thermoelectric performance Mg2Sn, which tends to deliquesce in air, a unique application prospect. It elucidates a pathway for utilizing thermoelectric effects to synergistically enhance the electrochemical performance of metal-air batteries.