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, Li 4-x Na x Ti 5 O 12 (LNTO)-based composite solid electrolytes (CSEs) were developed to enhance the interface stability and electronic insulation. The CSE is composed of Li 3.88 Na 0.12 Ti 5 O 12 (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|LiFePO 4 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. The Li|LNTO3|LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cell could also operate over 100 cycles at 1 C. This study offers an effective method for preparing commercial CSEs for SSBs. Graphical A low-cost and stable solid-state electrolyte based on Sodium-doped Li 4-x Na x Ti 5 O 12 is prepared by the typical casting method. Due to its excellent interfacial stability with lithium metal anode, the lithium metal battery of Li||LFP at 0.5 current density shows excellent cycling stability (154.5 mAh g −1 for 200 cycles, 97.6 % capacity retention and over 99 %Coulombic efficiency).