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X-ray absorption of the effect of plasticizers on ion-pair dissociation in a poly(ethylene oxide)-potassium salt complex

Journal Article · · Journal of the Electrochemical Society; (United States)
DOI:https://doi.org/10.1149/1.2043928· OSTI ID:6558987
; ; ;  [1]; ;  [2];  [3];  [4]
  1. Brookhaven National Lab., Upton, NY (United States)
  2. Moltech Corp., Stony Brook, NY (United States)
  3. Polytechnic Univ., Brooklyn, NY (United States)
  4. Univ. of Kentucky, Lexington, KY (United States)

Polyethylene oxide (PEO)-salt systems are an important new class of electrolytes that are being considered for use in high specific energy rechargeable lithium batteries. Near-edge X-ray absorption fine structure (NEXAFS) spectra, at the potassium K edge, were obtained for a potassium salt in the following systems: (1) a propylene carbonate (PC) solution, (2) a modified carbonate (MC3) solution, and (3) poly(ethylene oxide) (PEO)-potassium salt complexes with either PC or MC3 as a plasticizer. MC3 is a new plasticizer developed in the authors' laboratory which is similar to PC except that, instead of a methyl group, there are three ethylene oxide units attached to the 4-position. By examining the NEXAFS of various potassium salt reference systems, it was found that the white line splitting in the near-edge region was correlated with ion-pairing. The degree of white line splitting was used to study ion-pair dissociation effects of PC and MC3 qualitatively. When used as a solvent, MC3 has a stronger ion-pair dissociation effect compared to PC. When used as a plasticizer in a PEO-potassium salt complex, the enhancement effect on ion-pair dissociation of MC3 is superior to PC. These results were corroborated by Raman spectroscopy which showed that MC3 has a stronger ion-pair dissociation effect than PC.

DOE Contract Number:
AC02-76CH00016
OSTI ID:
6558987
Journal Information:
Journal of the Electrochemical Society; (United States), Journal Name: Journal of the Electrochemical Society; (United States) Vol. 142:1; ISSN JESOAN; ISSN 0013-4651
Country of Publication:
United States
Language:
English