PVDF-HFP/LiTFSI based composite solid state electrolyte with different micromorphology of Li6.25Ga0.25La3Zr2O12 doping

Solid electrolytes are safer alternatives to liquid electrolytes. Adding Ga to lithium lanthanum zirconium oxide (LLZO) garnet-like solid-state electrolytes effectively improves their performance. The properties of solid-state electrolytes prepared using the two mainstream methods, namely, electrospinning and sol-gel, vary and directly affect the electrochemical performance of assembled batteries. In this study, we prepared Li 6.25 Ga 0.25 La 3 Zr 2 O 12 (Ga-LLZO) nanoparticles and nanofibers using the sol-gel and electrospinning methods, respectively. The battery was also assembled with composite film consisting of the poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer substrate within Ga-LLZO ceramic fillers. The electrolyte of the battery prepared by Ga-LLZO nanofibers has better conductivity. We fabricated a Li|10 wt% Ga-LLZO nanofiber/PVDF-HFP/60 wt% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)|LiFePO 4 button battery using the optimal concentration. The device demonstrated a stable cycle lasting up to 700 h, a Coulombic efficiency of 98%, a capacity retention rate of 96.5%, and an electrochemical window up to 5 V vs Li/Li + at room temperature. Over time, a suitable contact interface generated a positive feedback loop. The ionic conductivity was 1.1 × 10 −4 S·cm −1 . The newly prepared electrolyte films aid the fabrication of future solid electrolytes.