Ultrasmall nanocrystalline CeO2 fillers improving the performance of PVDF-based polymer electrolytes for lithium metal batteries

Abstract

PVDF-based polymer electrolytes have been widely studied because of their mechanical strength, easy processing, and excellent thermal/chemical stability. However, pure PVDF faces the challenges of low ionic conductivity and insufficient interface stability with the electrodes. Herein, we propose a facile strategy to fabricate Ce-MOF-derived rod-like nanocrystalline CeO₂ into PVDF-HFP polymer electrolytes for Li metal batteries. The composite polymer electrolytes (CPEs) achieved enhanced ionic conductivity and interfacial stability. Notably, the CPEs with ultrasmall nanocrystalline CeO₂ demonstrated superior Li⁺ transport kinetics (5.04 × 10⁻⁴ S cm⁻¹), lithium dendrite suppression and an extended electrochemical stability window up to 4.6 V. When applied in Li|LiMn_0.6Fe_0.4PO₄ full batteries, the quasi-solid polymer electrolyte system maintained a discharge capacity of 94 mAh g⁻¹ after 100 cycles at 0.5C, delivering good cycling stability and rate capability, and retained 99% capacity after 500 cycles at 1C. This study demonstrates that functional CeO₂ nanocrystals with tailored structures can effectively enhance the performance of PVDF-based polymer electrolytes, providing a promising strategy for the development of solid-state lithium metal batteries.