LAUSR

Abstract Composite solid electrolytes (CSEs) exhibit high ionic conductivity and flexibility due to the intimate interactions between ceramic and polymer matrix, and it is of practical interest to enhance CSEs performance. Herein, a flexible, high ion conductive, and electrochemically stable CSE, consisting of three-dimensional (3D) interconnected Li7La3Zr2O12 (LLZO) framework and poly (ethylene oxide) - LiC2F6NO4S2 (PEO-LiTFSI) polymer, has been successfully prepared using lignosulfonate/cellulose nanofiber (LS-CNF) networks as a bio-template. The 3D porous LS-CNF network effectively promotes the adsorption and dispersion of LLZO precursors, which, upon calcination, leads to the formation of interconnected LLZO framework with homogeneous and small ceramic branches, thus offering multiple ion conductance pathways. The as-prepared CSE shows very high ionic conductivity of 1.37 × 10−4 S cm−1 and a high lithium ion transference number of 0.59 at 30 °C with a wide electrochemical stability window of 5.4 V vs. Li/Li+. The assembled LIBs exhibit a high initial capacity of 134 mAh·g−1 at 0.5C even after 100 cycles. This facile strategy for designing 3D interconnected and durable LLZO frameworks reveals great potential to develop high-performance solid-state electrolytes for the next-generation high energy density LIBs.