Ionic Conductivity Thermogravimetry Measurements of Starch-Based Polymeric Electrolytes

Natural polymers are a very interesting matrix to obtain solid polymeric electrolytes (SPE). The principal advantage comes from their particularly interesting biodegradation properties due to the natural origin and also very low cost and good physical and chemical properties. These polymers contain heteroatoms in their structure and for this reason can interact with protons or lithium ions leading to the ionic conduction. Among different natural polymers, starch-based SPEs show good opto-electrochemical characteristics and can be applied to electrochemical devices. This work presents the results of starch and starch derivatives-based electrolytes, which were characterized by impedance spectroscopy and thermal analysis. The ionic conductivity results obtained for these SPEs varied from 10−6 S/cm to 10−4 S/cm at room temperature, depending on the sample, and increased following Arrhenius model. The samples showed good stability up to 200°C evidenced by thermal analysis (TGA). Good conductivity results combined with transparency and good adhesion to the electrodes have shown that starch-based SPEs are very promising materials to be used as solid electrolytes in electrochromic devices.