Ion-ion interactions and lithium stability in a crosslinked PEO containinglithium salts

The electrochemical properties of a solid polymer electrolyte prepared by c hemical crosslinking of PEO 2000 and containing LiAsF6 or LiCF3SO3 were inv estigated for electrochemical window, lithium stability and lithium/ electr olyte interface stability. FTIR spectroscopy of the salt anion (AsF6- and C F3SO3-) was also used to determine the nature and the extent of ion pairing and ion aggregation in these crosslinked electrolytes. The lithium corrosi on appears as a diffusion limited process as the coulombic efficiency of a lithium deposit decreases with the square root of the contact time of lithi um with the crosslinked PEO. Impedance parameters are consistent with an in crease of the passivating layer upon storage. Their values strongly differ with the salt anion. (C) 1998 Elsevier Science Ltd. All rights reserved.