Engineering Ion Conduction Nanodomain Spacing and Interface Environment for Ultrastable All-Solid-State Lithium Metal Batteries

Abstract

Block copolymer electrolytes are of great interest due to the combination merits of ion conduction and mechanical strength. However, there lacks a comprehensive understanding on the role of nanodomain spacing in ion-dipole coordinating environment and interface environment. Herein, the lithium salts with varied binding energy are chosen to tune nanodomain spacing in Polyether-block-Polyamide (PEO-PA) polymer. Spectra characterizations in combination with molecular dynamic simulations systematically demonstrate adding LiFSI salts with lower binding energy contributes to forming larger PEO nanodomain spacing and clarifies the relationship between nanodomain spacing and ion-dipole coordinating environment as well as interface environment. The larger PEO nanodomain spacing in LiFSI doping PEO-PA electrolytes (AEOF) creates a loosely Li+-EO group coordinating environment and improves pristine interface contact. In addition, the formation of solid-electrolyte interphase rich in LiF and Li3N enhances interfacial stability. Therefore, the ionic conductivity of AEOF electrolytes is significantly improved. Furthermore, the Li||AEOF||Li cells exhibit extraordinary cycling life over 10000 h (416 days) at 0.1 mA cm−2 with a capacity of 0.1 mAh cm−2. This study provides a new insight into the ion-dipole coordinating environment and interface environment, which benefits the theory-guided design of all-solid-state polymer electrolytes.