Improved ionic conductivity and enhancedinterfacial stability of solid polymer electrolytes with porous ferroelectric ceramic nanofibers

Abstract

Solid polymer electrolyte has aroused widespread research interest due to the potential to achieve high-safety and high-energy density lithium metal batteries. However, its practical application has been hampered by low ion conductivity. In this work, we innovatively prepare porous ferroelectric ceramic Bi4Ti3O12 nanofibers (BIT NFs) to construct fast conductive networks of Li+ ions in the poly(ethylene oxide) (PEO)/lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) system to achieve the great improvement of lithium ion conductivity (6.25 × 10−4 S cm−1 at 50 °C). Various electrochemical characterizations and density functional theory (DFT) calculations reveal that the abundant oxygen vacancies possessed by the ferroelectric ceramic nanofibers help the accelerated dissociation of LiTFSI and promote the rapid transfer of free Li+ ions. Notably, thanks to the piezoelectric properties of BIT NFs, the dynamic regulation of the electrolyte/lithium interface is realized. The assembled lithium symmetric cells with the composite electrolyte exhibit excellent cycle stability (without short circuiting after 3000 h at 50 °C), and the all-solid-state LiFePO4||Li cells present a superior cycling performance (remained 118.2 mA h g − 1 after 1000 cycles at 0.2 mA cm−2).