Ionic conduction in PEO-PAN blend polymer electrolytes

Polymer electrolyte films consisting of polyethylene oxide (PEG), polyacryl onitrile (PAN), LiClO4 and a mixture of ethylene carbonate (EC) and gamma-b utyrolactone (BL) were examined in order to obtain the best compromise betw een high conductivity, homogeneity, dimensional and electrochemical stabili ty. Measurements of electrical conductivity, differential scanning calorime try and linear sweep voltammetry have been carried out for films of (50-x)P EO-xPAN-7LiClO(4)-43EC/BL and (50-x)PEO-xPAN-12LiClO(4)-38EC/BL with x=10, 20, 30, 40 and 50. When the EO/AN ratio is lower, the PEG-rich crystalline domains are nearly absent. The PEG-PAN blend film is more likely to be a ge l-electrolyte than a plasticized PEG-salt electrolyte. The Li+ ions in thes e films seem to migrate primarily through the solvent domains as in the gel electrolytes. The highest room temperature conductivity of 1.2 x 10(-3) S cm(-1) is found for a film of 10PEO-40PAN-12LiClO(4)-38EC/BL. The beneficia l effects of PEO blending with PAN-based electrolytes are in comparable ion ic conductivity, better dimensional stability and wider electrochemical sta bility. (C) 2000 Elsevier Science Ltd. All rights reserved.