Dielectric relaxations and ion transport study of NaCMC:NaNO₃ solid polymer electrolyte films

Na⁺ ion-conducting solid polymer electrolyte (SPE) of sodium salt of carboxymethyl cellulose (NaCMC) doped with sodium nitrate (NaNO₃) was developed by solution casting method. FTIR technique confirmed the formation of hydrogen bonding between NO3−anion and functional groups of NaCMC. XRD study revealed the low degree of crystallinity that reduced upon doping. Impedance spectroscopy was adapted in order to analyze the conductivity and dielectric relaxation phenomena of the polymer-salt complex. FTIR deconvolution technique was employed to understand the factor that influences the ionic conductivity in SPE; concentration of mobile ions and ionic mobility both play a vital role. Ion transference number has been found out to be > 0.97 for all samples indicating that the conducting species are primarily ions. The highest ionic conductivity of ̴ 3 × 10⁻³ Scm⁻¹ with the mechanical strength of 30.12 MPa was achieved for a host containing 30 wt.% NaNO₃ at ambient temperature.