The Critical Role of Functionalised Filler in Li‐Polymer Composite Electrolyte: Ionic Conductivity and Dielectric Relaxation Behavior Study

Abstract

Herein, an alternative structural design approach for a polymer composite electrolyte based on a PVDF host and a PVPfunctionalised LATP ceramic filler has been proposed. The results demonstrate that the PVP-coated surface filler interacts with the PVDF host, enhancing the polar properties of the polymer matrix and promoting Li-salt dissociation. Similarly, residual DMF solvent contributes to the dissociation of LiTFSI, forming a complex with a locally high concentration of Li+ and ionic liquid properties. Furthermore, the PCE containing 10wt% PVP-LATP filler exhibits maximum ionic conductivity (1.8×10−4Scm−1 at 30°C). However, increasing the filler loading decreases the ionic conductivity due to the inhomogeneous dispersion of the filler particles. The maximum ionic conductivity correlates with the minimum relaxation time (τtanδ) at 30°C. This supports the idea that the functionalised filler enhances the flexibility of the polymer chain's segmental mobility, thereby facilitating ion hopping in the host matrix. Finally, the ac frequency-dependent conductivity analysis of the PCE membranes shows that the conduction mechanism follows the correlated barrier hopping (CBH) model.