Theoretical Study of Polyvinylidene Halides (PVDX) as Solid Polymer Electrolytes with LiClO4
Sylwia Kozdraa *, Michiko Atsumib
a Łukasiewicz Research Network - Institute of Microelectronics and Photonics: Al. Lotników 32/46, Warszawa 02-668, Poland, *Sylwia.Kozdra@imif.lukasiewicz.gov.pl, +48 22 6395803
b Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, Box 1033, N-0315, Norway
Methods such as Density Function Theory (DFT) can be successfully applied to studying polymers and their composites. Polyvinylidene halides (PVDX, X = F, Cl, Br, I) have gained attention as potential materials for solid polymer electrolytes, particularly for energy storage applications due to the presence of atoms with increasing electronegativity. Understanding the interactions between polymer chains and lithium salts, such as lithium perchlorate (LiClO4), is crucial for optimizing their ion conduction properties and reactivity.
Models reflecting the structure of a composite composed of different varieties of polyhalides with the addition of LiClO4 were optimized and characterized using DFT methods. The stability and reactivity of PVDX composites were analyzed and compared. Cluster models for both PVDX-α and PVDX-β were investigated, considering geometry, electrostatic potentials, electron density, Gibbs free energy difference, and the HOMO-LUMO gap. Structural modifications, including changes in the energetic gap, geometric distortions, and reactivity, were observed upon interaction with LiClO4. Theoretical results were compared with experimental data, particularly FTIR spectra, which showed that the crystalline form of PVDF significantly influences the ionic conductivity and functionality of polymer electrolytes. The analysis revealed that PVDF-β and PVDC-β exhibited favorable dissociation of LiClO4 due to weaker interactions with lithium ions in the β form. Additionally, a decrease in the HOMO-LUMO gap with increasing atomic number of halogens suggests easier electronic transitions in heavier halogens [1].
Calculated data provided valuable insights into the conductive properties of solid polymer electrolytes, particularly in the PVDF and PVDC-β forms, highlighting their potential for energy storage applications.
[1] Kozdra, S.; Atsumi, M.; Solid polymer electrolytes with LiClO4 – Theoretical study of polyvinylidene halides, Materials Today Communications, 39, 2024, 109019. DOI: 10.1016/j.mtcomm.2024.109019.