Electrical transport behaviour of bio-polymer electrolyte system: Potato starch + ammonium iodide

A new bio-polymer electrolyte system is prepared by mixing NH4I with potato starch. Prepared material is an ionic conductor having ionic transference number (tion) ∼0.95 and ambient electrical conductivity ∼2.4 × 10−4 S/cm. Relation between the conductivity trend, mobile ion concentration factor (K) and mobility factor (μf) with respect to salt concentration and temperature, is established. The optical micrograph of starch + NH4I system indicated typical starch–iodine relationship in acidic medium. In conductivity formulism three different regions for power law exponent (n) having values between 0 < n < 2 is found. The regions are associated with dc conductivity, NCL and superlinear like behaviour. In starch electrolyte, NCL region is obtained at room temperature and low frequency region. Material is humidity immune up to 77% relative humidity and a very small variation with temperature has been found hence results are encouraging for possible use of starch based electrolytes in humidity immune devices.

► System is biodegradable electrolyte.
► System is ambient immune, seems promising for devices showing stable performance.
► NCL occurred at low frequency and room temperature against theoretical prediction.
► Conductivity is explained in terms of K, μf and n/n0.