Dual‐Solvent Li‐Ion Solvation Enables High‐Performance Li‐Metal Batteries

• DOI: 10.1002/adma.202008619
• Publication Date: 2021-05-10T06:01:01Z
• Authors: Hansen Wang; Zhiao Yu; Xian Kong; William Huang; Zewen Zhang; David G. Mackanic; Xinyi Huang; Jian Qin; Zhenan Bao; Yi Cui
• Keywords: Dimethoxyethane

Abstract Novel electrolyte designs to further enhance the lithium (Li) metal battery cyclability are highly desirable. Here, fluorinated 1,6‐dimethoxyhexane (FDMH) is designed and synthesized as solvent molecule promote stability with its prolonged –CF 2 – backbone. Meanwhile, 1,2‐dimethoxyethane used a co‐solvent enable higher ionic conductivity much reduced interfacial resistance. Combining dual‐solvent system 1 m bis(fluorosulfonyl)imide (LiFSI), high Li‐metal Coulombic efficiency (99.5%) oxidative (6 V) achieved. Using this electrolyte, 20 µ Li||NMC batteries able retain ≈ 80% capacity after 250 cycles Cu||NMC anode‐free pouch cells last 120 75% retention under 2.1 L mAh −1 lean conditions. Such performances attributed anion‐derived solid‐electrolyte interphase, originating from coordination of Li‐ions stable FDMH multiple anions in their solvation environments. This work demonstrates new design strategy that enables high‐performance multisolvent Li‐ion rationally optimized molecular structure ratio.