Fiber‐Reinforced Composite Polymer Electrolytes for Solid‐State Lithium Batteries

• Published in: Advanced sustainable systems (Online) 2022-03, Vol.6 (3), p.n/a
• Main Authors: Gao, Longxue, Tang, Bin, Jiang, Haoyang, Xie, Zhaojun, Wei, Jinping, Zhou, Zhen
• Format: Article
• Language: English
• Subjects: composite polymer electrolytes; fiber‐reinforced structures; lithium metal batteries; solid‐state electrolytes
• ISSN: 2366-7486; 2366-7486
• DOI: 10.1002/adsu.202100389

Solid‐state composite polymer electrolytes (CPEs) have attracted much attention due to their flexibility and low interfacial impedance. Researchers have been improving their ionic conductivity at room temperature, ionic transference number, and (electro)chemical stability. Here, a fiber‐reinforced CPE is prepared by infusing polyethylene oxide (PEO) and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) electrolytes onto polyacrylonitrile (PAN) nanofiber networks. The introduction of both inorganic ceramic filler LLZTO and plasticizer succinonitrile (SN) reduces the crystallinity of PEO, increases the solubility of lithium salts, and further improves ionic transport kinetics. The ionic conductivity of CPE is 2.57 × 10−4 S cm−1 at 30 °C and the lithium‐ion transference number is 0.6. Meanwhile, the high content of LLZTO (60 wt.%) brings a better capability to suppress lithium dendrites, and thus lithium symmetrical cells based on this CPE can be stably cycled for up to 500 h. In addition, the PAN fiber network endows CPE with high mechanical strength and high oxidation resistivity, and accordingly an electrochemical stability window as high as 4.7 V. Both LiFePO4/CPE/Li and LiNi1/3Co1/3Mn1/3O2/CPE/Li cells can be operated at 30 °C for 100 cycles. This work provides a promising strategy for the preparation of thin CPEs for solid‐state lithium metal batteries. A fiber‐reinforced composite polymer electrolyte is prepared with high ionic conductivity and lithium‐ion transference number. The synergistic effects of ceramics, plasticizers, and fiber networks and the compatibility of the composite electrolyte with both cathodes and Li metal anodes endow solid‐state Li batteries with high capacity and coulombic efficiency.