Polymer electrolytes have received much attention in Li-ion battery research because of their unique properties, such as, high ionic conductivity, high mechanical strength including good electrode-electrolyte contact. A major research has been focused on improving the conductivity while retaining the mechanical stability of polymer electrolytes. In this context, ionic liquid-based gel polymer electrolytes are an excellent candidate. A detailed NMR investigation of PMMA-ILs gels electrolytes probing the structure and dynamics of ions was recently reported.[1] The presence of ILs in polymer matrix not only improves the conductivity but also enhances the self-healing capability. In another study, self-healing capability that reduces the dendrite formation at the interface has been discovered, for example, in PVDF-HFP-ILs electrolyte.[2] In this regard, this work reports the possible ways to enhance the ionic conductivity of such polymer electrolyte further by adding Al₂O₃ nanofibers. A series of PVDF-HFP-ILs with 1M LiTFSI in EMIMTFSI at different ratios of Al₂O₃nanofibers were prepared through solution cast technique. The dynamics of ions confined within polymer-Al₂O₃ matrix was explored through Impedence and PFG NMR spectroscopy. The amorphocity and the distribution of Al₂O₃ nanofibers are studied through XRD and SEM-EDX analyses. Lastly, the local structure of ions and their interaction with polymer and Al₂O₃ nanofibers were established through a detailed solid-state NMR analyses detecting ¹H, ²⁷Al, ¹³C, ¹⁹F, ⁷Li nuclei including 2D ¹³C{¹H} HETCOR experiments. A reasonable enhancement in terms of ionic conductivity was observed with the addition of Al₂O₃ nanofibers, which improves the conducting pathways within the polymer network.

[1] M. N. Garaga, N. Jayakody, C. C. Fraenza, B. Itin, and S. Greenbaum, Journal of Molecular Liquids 329, 115454 (2021).

[2] T. Chen, W. Kong, Z. Zhang, L. Wang, Y. Hu, G. Zhu, R. Chen, L. Ma, W. Yan, Y. Wang, J. Liu, and Z. Jin, Nano Energy 54, 17 (2018).