Influence of Humidity on Ionic Conductivity Measurements of Solid Polymeric Electrolytes Obtained from Plasticized Starch
Denise Rodrigues and Agnieszka Pawlicka
Solid ionic conductors are key material to develop all-solid components devices such as batteries, capacitors and sensors. Among many types of solid electrolytes solid polymeric ones were proposed based on polysaccharides like cellulose derivatives and starch. These polymers can be modified by a plasticization process with glycerol and after the addition of LiClO4 they can be obtained in a transparent film form that shows excellent conductivity values. However the humidity is a serious problem for these materials, as it can promote an increase in crystallinity and a decrease in the conductivity values. In order to observe the conductivity behavior as a function of the relative humidity, the samples of amylopectin rich starch plasticized with 30% of glycerol and containing LiClO4 with concentration [O]/[Li] = 11 and 14 were prepared. The samples were stocked in small boxes with relative humidity of 22, 33, 43, 55, 75 and 84% for several hours. These films were characterized by electrochemical impedance measurements and weight changes.