Customization nanoscale interfacial solvation structure for low-temperature lithium metal batteries†

Abstract

Regulating the nanoscale interfacial solvation structure involving ion coordination in the electric double layer is of significant importance for the construction of a stable and rapid ion-transport solid–electrolyte interface for revolutionary lithium metal batteries (LMBs) operated under low-temperature serving conditions. Herein, an efficient strategy involving the use of PMETAC polymer brushes to regulate the nanoscale interfacial solvation structure is proposed, which is universal to different electrolyte chemistries and operating temperatures. Combined attenuated total reflection analysis and theoretical simulations revealed the unique interfacial solvation structure and the underlying synergistic mechanism. Owing to the electrostatic interaction between the quaternary amino nitrogen of the polymer brushes and electrolyte anions, as well as the unique steric hindrance effect originating from the polymer brushes, solvent molecules were excluded from the first inner solvation shell and more anions entered the electric double layer to participate in Li-ion coordination, thus prompting the formation of a stable inorganic-rich SEI with favorable ion transport. With the unique nanoscale interfacial solvation structure, the assembled LMBs achieved stable operation at room temperature for over 1.7 years and at a low temperature of −20 °C. More excitingly, the strategy could support the industrial manufacturing of Ah-level anode-free Li metal pouch cells. This work reveals the importance of regulating the nanoscale interfacial solvation structure, promoting the realistic applications of high-energy LMBs for operation under various service conditions.