Study of Optical, Thermal, Electrical, and Impedance Properties of Li₄Ti₅O₁₂-Based PEO/SA Biopolymer Blend Electrolytes for Lithium-Ion Batteries

Nanocomposites composed of polyethylene oxide (PEO) and sodium alginate (SA), containing varying contents of lithium titanium oxide nanoparticles (Li 4 Ti 5 O 12 NPs), were synthesized by solution casting technique. Li 4 Ti 5 O 12 was incorporated into PEO/SA blend and is a valuable biopolymer for its biocompatibility, solubility and eco-friendliness. Structural analysis via X-ray diffraction spectroscopy revealed a decrease in the crystallinity of PEO/SA matrix with increasing nanoparticle content. Complementary Fourier transform infrared analysis verified the presence of strong molecular interactions between Li 4 Ti 5 O 12 and the blend chains. Scanning electron microscopy verified a uniform dispersion of Li 4 Ti 5 O 12 within PEO/SA blend, contributing to the improved properties of the electrolytes, while optical analysis showed a decrease in the bandgap energy, indicating enhanced light absorption and improved suitability for applications in nanodielectric devices. The thermal stability of PEO/SA/Li 4 Ti 5 O 12 electrolyte samples was improved as shown by thermogravimetric analysis. Furthermore, a significant improvement in the ionic conductivity of the filled samples was observed, attributed to the reduced bulk resistance and improved charge transport pathways. Dielectric studies further showed improved dielectric permittivity and reduced dielectric losses for filled samples, enhancing the material’s charge storage capability. These findings highlight the potential of PEO/SA/Li 4 Ti 5 O 12 biopolymer electrolytes for advanced applications in nanodielectric devices and lithium-ions batteries.