Flexible ion-conducting membranes with 3D continuous nanohybrid networks for high-performance solid-state metallic lithium batteries

Polyethylene oxide (PEO)-based electrolytes are considered as one of the most promising solid-state elec-trolytes for next-generation lithium batteries with high safety and energy density; however, the draw-backs such as insufficient ion conductance, mechanical strength and electrochemical stability hinder their applications in metallic lithium batteries. To enhance their overall properties, flexible and thin com-posite polymer electrolyte (CPE) membranes with 3D continuous aramid nanofiber (ANF)- Li1.4Al0.4Ti1.6(PO4)3 (LATP) nanoparticle hybrid frameworks are facilely prepared by filling PEO-LiTFSI in the 3D nanohybrid scaffolds via a solution infusion way. The construction of the 3D continuous nanohybrid networks can effectively inhibit the PEO crystallization, facilitate the lithium salt dissociation and meanwhile increase the fast-ion transport in the continuous LATP electrolyte phase, and thus greatly improving the ionic conductivity (-3 times that of the pristine one). With the integration of the 3D con-tinuity and flexibility of the 3D ANF networks and the thermostability of the LATP phase, the CPE mem-branes also show a wider electrochemical window (-5.0 V vs. 4.3 V), higher tensile strength (-4-10 times that of the pristine one) and thermostability, and better lithium dendrite resistance capability. Furthermore, the CPE-based LiFePO4/Li cells exhibit superior cycling stability (133 mAh/g after 100 cycles at 0.3 C) and rate performance (100 mAh/g at 1 C) than the pristine electrolyte-based cell (79 and 29 mAh/g, respectively). This work offers an important CPE design criteria to achieve comprehensively -upgraded solid-state electrolytes for safe and high-energy metal battery applications.(c) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.