Self-tracking, solvent-free low-dimensional polymer electrolyte blends with lithium salts

• Published in: Journal of power sources Vol. 97; pp. 641 - 643
• Main Authors: Zheng, Y., Chia, F., Ungar, G., Wright, P.V.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 01.07.2001; Elsevier Sequoia
• Subjects: Applied sciences; dc conductivity; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Lithium electrodes; Low-dimensional; Polymer blends; Polymer electrolytes; Self-tracking; Lithium electrodes; Self-tracking; Polymer blends; dc conductivity; Polymer electrolytes; Low-dimensional; Alkali metal Compounds; Ionic conductivity; Polymer solid electrolyte; Secondary cell; Electric batteries; Ethylene oxide polymer; Electrochemical properties; Lithium perchlorates; Organic electrolyte storage battery; Electrochemical polarization; Solid electrolyte storage battery; Furan derivative polymer
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/S0378-7753(01)00747-9

Solvent-free polymer electrolyte blends of the amphiphilic polyethoxide ( I) and the polytetrahydrofuran copolymer ( II) with LiClO 4 or LiClO 4/LiBF 4 mixture have been prepared. In II A is either CH 2 ( IIC1) or CH 2C(CH 2)CH 2 ( IID4), dc measurements using Li electrodes on the cells (Li | I/ II-Li salt | Li) demonstrate a ‘self-tracking’ process over ca. 24 h during which time conductivities increase from ca. 10 −6 to 10 −3 S cm −1 at 25 and 30°C. The dc results are supported by ac impedance measurements using indium tin oxide (ITO) electrodes in which the complexes undergo transitions at ca. 90°C to give a conductivity after cooling of 6×10 −4 S cm −1 at 20°C with low temperature dependence. Structural analysis and molecular dynamics modelling indicate that the cations occupy unimpeded helices of I and anions are located in the interhelical spaces. Mechanisms of ‘tracking’ involving shear-induced orientation of polymer I by polymer II and the redistribution of ions between I and II following imposition of the field are proposed.