Critical Ingredients Revitalize Magnesium-Metal Batteries: Rationality and Challenges

Multivalent-metal batteries hold tremendous promise in solving safety and sustainability problems encountered by common lithium-ion batteries, but the lack of ideal electrolyte solutions restricts their large-scale adoption. Tuning electrolyte structures with functional ingredients, especially amines/methoxy-based amines and phosphates, can revitalize multivalent-metal anodes and high-voltage cathodes in conventional electrolytes, unlocking their full potential. However, a rational and clear understanding of the implications of these ingredients, notwithstanding critically important to commercially available electrolyte design, has not been widely accepted. This concise perspective aims to provide timely analysis and discussion on ingredients' functionalities of solvation shell speciation, interphase evolution, and consequently metal plating/stripping kinetics acceleration. In addition to prevailing coordination interactions, fresh understandings of intermolecular ionization/association and unique interphase formation are underscored by the close relationship between electrolyte chemistries and weakly passivated interphase properties. The existing understandings and proposed outlooks are expected to promote the next breakthroughs for rechargeable multivalent-metal batteries.