Facile synthesis of highly flexible sodium ion conducting polyvinyl alcohol (PVA)-polyethylene glycol (PEG) blend incorporating reduced graphene-oxide (rGO) composites for electrochemical devices application

Blend polymer composite electrolyte (BPCE) films consisting of Polyvinyl alcohol (PVA)-Polyethylene glycol (PEG) with Sodium nitrate (NaNO₃) and different weight percent of reduced graphene-oxide (rGO) were prepared by standard solution cast technique. The structural properties were analysed by the X-ray diffraction of the nanocomposite shows the uniform distribution of rGO in the polymer matrix and confirms the amorphous nature of the polymer blend composite films. FTIR studies clearly shows the confirmation of strong interaction between polymer, rGO (nanofillers) and Na-ion. The chemical bond formation spectrum or structure is analyzed by Raman spectroscopy to understand the chemical variation of the polymer composite, which confirm the presence of rGO in the composites. Thermal analysis DSC / TGA results show that the amount of rGO in the blend polymer matrix has a significantly improved the thermal stability of blend polymer composite films. The surface morphology of the as prepared films was analysed by field emission scanning electron microscope. The electrical properties of as prepared films show the highest ionic conductivity σ ∼ 10^–6 S cm⁻¹ in 30 wt.% based BPCE films (at 323 K). The dielectric properties of blend polymer composites films were measured over a wide frequency range of 10^–1 to 10⁷ Hz at two different temperatures, which illustrates the increment in a.c conductivity and dielectric permittivity of blend polymer composite films by adding the rGO contents. The performance of the electrochemical stability window was found up to (∼ 4.15 V vs.Na⁺/Na) and ionic transference numbers found ∼ 0.91 at room temperature. Ion transport mechanism is the key parameter and reveals better ion transportation in electrolytes during electrochemical analysis.