PVDF Coated Li₇La₃Zr₂O₁₂ Scaffold for Semi-Solid-State Electrolyte

Semi-solid batteries integrate a synergy of benefits from both liquid and solid electrolytes, which mitigates the risk of flammability and fire hazard from sole reliance on liquid electrolytes. Moreover, they demonstrate lower interfacial resistance compared to solid electrolytes alone. In this study, we utilize the high-ionic-conducting Li₃La₂Zr₇O₁₂ (LLZO) (10^-3 to 10^-4 S/cm) as the stable oxide solid electrolyte and electrochemically stable PVDF as a polymer matrix absorbing liquid electrolyte to synthesize an ionic-conducting and electrochemically stable scaffold for semi-solid batteries. To address the alkalization of the solvent by Li₂CO₃ on the LLZO surface inducing the gelation of PVDF when mixing LLZO powder and PVDF binder, we fabricate the free-standing LLZO scaffold with LLZO powder and EVA binder first, followed by coating PVDF on the surface of LLZO scaffold. As a result, our PVDF-coated LLZO scaffold shows the high thermal stability, enduring temperatures over 200°C onto the hotplate. In addition, a Li//NCM811 half-cell assembled using LLZO@PVDF combined with a liquid electrolyte records the reversible capacity of 200mAh g^-1 at 0.5C without voltage drop during charging-discharging cycles. Notably, our LLZO@PVDF scaffold can be easily fabricated without the process for removing Li₂CO₃ on the surface of LLZO, which will open a new avenue for the development of semi-solid-state batteries.