A Solid Electrolyte Based on Sodium‐doped Li4‐xNaxTi5O12 with PVDF for Solid State Lithium Metal Battery

Solid-state batteries (SSBs) present a potential pathway for advancing next-generation lithium batteries, characterized by exceptional energy density and enhanced safety performance. Solid-state electrolytes have been extensively researched, yet an affordable option with outstanding electrochemical performance is still lacking. In this work, Li4-xNaxTi5O12 (LNTO)-based composite solid electrolytes (CSEs) were developed to enhance the interface stability and electronic insulation. The CSE is composed of Li3.88Na0.12Ti5O12 (LNTO3) and poly (vinylidene fluoride) (PVDF) with a proportion of 20 wt.% exhibited high ionic conductivity (4.49 × 10-4 S cm-1 at a temperature value equal to 35 °C), high ionic transfer number (equal to 0.72), low activation energy (equal to 0.192 eV), and favorable compatibility with the Li metal anode. The Li|LNTO3|LiFePO4 cell, tested at a 0.5 C current density, demonstrated 154.5 mAh g-1 of outstanding cycling stability for 200 cycles, capacity retention of 97.6% along with a Coulombic efficiency of over 99%) as well as a significant average specific capacity of 127.8 mAh g-1 over 400 cycles at 5 C. This study offers an effective method for preparing commercial CSEs for SSBs.