LAUSR

Description Efficient, rechargeable Mg and Ca batteries Divalent rechargeable metal batteries such as those based on magnesium and calcium are of interest because of the abundance of these elements and their lower tendency to form dendrites, but practical demonstrations are lacking. Hou et al. used methoxyethyl amine chelants in which the ligands attach to the metal atom in more than one place, modulating the solvation structure of the metal ions to enable a facile charge-transfer reaction (see the Perspective by Zuo and Yin). In full battery cells, these components lead to high efficiency and energy density. Theoretical calculations were used to understand the solvation structures. —MSL Chelating ligands promote fast charge-transfer kinetics for Mg and Ca batteries with substantially lowered overpotentials. Rechargeable magnesium and calcium metal batteries (RMBs and RCBs) are promising alternatives to lithium-ion batteries because of the high crustal abundance and capacity of magnesium and calcium. Yet, they are plagued by sluggish kinetics and parasitic reactions. We found a family of methoxyethyl-amine chelants that greatly promote interfacial charge transfer kinetics and suppress side reactions on both the cathode and metal anode through solvation sheath reorganization, thus enabling stable and highly reversible cycling of the RMB and RCB full cells with energy densities of 412 and 471 watt-hours per kilogram, respectively. This work provides a versatile electrolyte design strategy for divalent metal batteries.