Enhanced Interfacial kinetics and Fast Na+ Conduction of Hybrid Solid Polymer Electrolytes for All-Solid-State Batteries

Abstract All-solid-state batteries suffer from drastic interfacial reactions between the solid electrolyte and electrode, which restricts the performance of the full cell. Herein, a hybrid solid polymer electrolyte with high ionic conductivity and stability has been fabricated by in-situ polymerization of poly(ethylene glycol) diacrylate (PEGDA) on glass fiber matrix, followed by polyethylene glycol (PEG) infiltration. Such hybrid electrolyte, namely GF@PEGDA@PEG (GFPP), is featured with an interconnecting ionic conducting network and demonstrates high ionic conductivities of 0.8 × 10−4 S cm−1 at 20°C and 4.5 × 10−3 S cm−1 at 60°C. The ex-situ Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR) of Na/GFPP/Na symmetrical battery proves the excellent stability of GFPP. Furthermore, in-situ Electrochemical Impedance Spectroscopy (EIS) analysis and in-situ Raman spectra confirm the enhanced interfacial dynamics achieved by GFPP, being conducive to the intercalation/ deintercalation of Na+. Meanwhile, the optical microscope and X-ray photoelectron spectroscopy (XPS) demonstrate the formation of a stable SEI film and limited interfacial side reaction by the incorporation of GFPP. Full sodium metal batteries based on GFPP have been assembled and demonstrated satisfactory electrochemical performance. After being tested for 1100 cycles at a rate of 0.3C, the Coulombic efficiency of Na3V2(PO4)3 (NVP) /GFPP/Na full cell remains at almost 99%, with a capacity retention of 91.4%.