Conductivity And Thermal Analysis Studies Of Solid Polymeric Electrolytes Based On Plasticized Hydroxyethyl Cellulose
by Gilmara Machado, Robert Prud''homme, Agnieszka Pawlicka Transparent film samples of hydroxyethyl cellulose (HEC) based on solid polymeric electrolytes (SPE) were prepared by the plasticization of HEC with
glycerol and addition of lithium perchlorate salt. SPEs with different quantities of glycerol and LiClO4 were studied by electrochemical impedance spectroscopy (EIS), Dynamic Mechanical Thermal Analysis (DMTA), TGA (Thermogravimetric Analysis) and DSC (Differential Scanning Calorimetry). The ionic
Conductivity measurements revealed that the sample containing
/=8 and 48% of glycerol showed the conductivity value of almost 10-4 S/cm at room temperature. The TGA analysis of electrolytes with high plastizant and salt concentrations showed 25% weight loss after heating to 130 oC, which can be related to the liberation of absorbed water. Finally, DMTA measurements showed changes attributed to the glass transition (Tg) evidenced by the decrease in the elastic modulus value and peaks in the tandelta curves. These results demonstrated that HEC is a good material to be used as a matrix for new solid polymeric electrolytes.
The production, stocking and distribution of energy are some of the main interests of industry and modern society. The development of new solid materials to be used as solid polymeric electrolytes offers an opportunity to create new systems of energy generation and storage that can revolutionize many industrial areas. Solid polymeric electrolytes represent a promising alternative to liquid electrolytes and inorganic crystals, which are used in batteries, sensors and electrochromic devices <1-3>. Ionic conductivity is usually associated with liquids, but it can also occur in the solid state as ceramics, nanocomposite, polymers or gels. Solid polymeric electrolytes consist of a salt dissolved in a Polymer matrix (in this case the plasticized HEC) forming an ion-conducting solid solution. However, for this application, the polymer has to possess certain properties, such as amorphous character, oxygen molecules in its structure, low glass transition temperature, electrochemical and dimensional stability, mechanical resistance and the possibility of forming relatively thin films or pellets <4-7>.
http://www.e-polymers.org
e-Polymers 2007, no. 115
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