Reductive Electron Redistribution Enables Ultrafast Charging Magnesium Batteries

Abstract

Solvation sheath rearrangement is recognized as a key strategy for modifying electrolytes to enhance the kinetics of magnesium batteries. However, its fundamental mechanism diverges significantly from that in Li-ion batteries and remains inadequately understood. Here, we elucidate the principle that solvation tuning essentially determines the distribution of reductive electrons, accumulation of which on ether molecules directly lead to the challenging reorganization and severe solvent decomposition. To address this, a series of organic monoamine salts are designed as additives to capture and stabilize the reductive electrons in the solvation sheath, and the screening guidelines are also proposed to promote the kinetics and reversibility of Mg plating/stripping. Accordingly, we demonstrate a Mg pouch cell with ultrahigh power density (50 C, 13 mA cm^-2 , 16.02 kW kg^-1 based on cathode), far surpassing all previous research. This work offers new insights into solvation tuning strategy that are crucial in designing high power density Mg batteries.