All-Solid-State Li-metal Batteries: Role of Blending PTFE in PEO with LiTFSI Salt as Composite Electrolyte with Enhanced Thermal Stability
Enhancing the ionic conductivity and thermal stability of solid electrolytes is crucial for the development of all-solid-state batteries. Here, we report PTFE (Polytetrafluoroethylene) as an additive to improve the ionic conductivity and thermal stability of PEO (Polyethylene Oxide) based electrolyte. The EIS measurements for composite electrolytes with different ratios of PEO and PTFE confirm the enhancement in the ionic conductivity at both room temperature as well as 60°C. For the EIS of electrolytes at room temperature, PEO100 showed the lowest ion-conductivity (2.254 × 10-08 S/cm); while electrolytes adding PTFE gave higher ion-conductivity (6.61958 × 10-08 S/cm). The charge-discharge measurement confirms that adding PTFE has improved capacity from 139 mAh/g to 163 mAh/g and cyclic stability. Furthermore, the composite electrolyte showed enhanced thermal stability as heat generation during the temperature increment is decreased to half for PTFE blended PEO composite electrolyte as compared to PEO. Our results show that the PEO-PTFE composite has the potential to use as solid electrolyte in Li batteries.