Silver nitrate doped chitosan acetate films and electrochemical cell performance

Chitosan acetate-silver nitrate (AgNO3) complexes were prepared in thin film form by the solution cast technique. The electrical conductivity σ of the films was measured by impedance spectroscopy. The plot of σ vs. dopant content indicates that σ increases with increasing dopant content up to a dopant amount of 0.25 g where σ reaches a maximum. The plot of In σT vs. 103/T (278 K ⩽ T ⩽ 313 K) for each film sample seems to obey the Arrhenius rule. Here σ is the electrical conductivity and T is temperature in Kelvin. From these plots the activation energy, EA was obtained and the graph of activation energy versus dopant content was plotted. From these plots the increase in σ can be explained in terms of the decrease in EA. The shape of the Cole-Cole plots seem to imply that the transport mechanism of Ag+ ions occurs by way of diffusion. The film with the highest ionic conductivity of 2.6 × 10−5 S cm−1 was used to fabricate Ag/AgNO3 — chitosan/I2 electrochemical cells. The average open circuit voltage of these cells is 0.672 V justifying the material to be an Ag+ ion conductor. By the electromotive force method, the ionic transference number of the film is 0.98 implying the low electronic conductivity of the material and its suitability as an electrolyte for electrochemical cell fabrication. Characteristics of such cells are presented and discussed.