Li_0.35La_0.55TiO₃ Nanofibers Enhanced Poly(vinylidene fluoride)-Based Composite Polymer Electrolytes for...

Using polymer electrolytes with relatively high mechanical strength, enhanced safety, and excellent flexibility to replace the conventional liquid electrolytes is an effective strategy to curb the Li-dendrite growth in Li-metal batteries (LMBs). However, low ionic conductivity, unsatisfactory thermal stability, and narrow electrochemical window still hinder their applications. Here, we fabricate Li_0.35La_0.55TiO₃ (LLTO) nanofiber-enabled poly(vinylidene fluoride) (PVDF)-based composite polymer electrolytes (CPEs) with enhanced mechanical property and wide electrochemical window. The results show that 15 wt % of LLTO nanofibers synergize with PVDF, giving a flexible electrolyte membrane with significantly improved performance, such as high ionic conductivity (5.3 × 10^-4 S cm^-1), wide electrochemical window (5.1 V), high mechanical strength (stress 9.5 MPa, strain 341%), and good thermal stability (thermal degradation 410 °C). In addition, an all-solid-state Li-metal battery of sandwich-type LiFePO₄/PVDF-CPE (15 wt % of LLTO)/Li delivers satisfactory cycling stability and outstanding rate performance. A reversible capacity of 121 mA h g^-1 is delivered at 1 C after 100 cycles. This work exemplifies that the introduction of LLTO nanofibers can improve the electrochemical performances of PVDF-based CPEs used as electrolytes for all-solid-state LMBs.