Accession Number:

ADA339928

Title:

Surface Chemistry and Electrochemistry at Electrode-Ionic Liquid Interfaces

Descriptive Note:

Final rept. 15 Apr 96-31 Jul 97

Corporate Author:

COVALENT ASSOCIATES INC WOBURN MA

Personal Author(s):

Report Date:

1997-08-25

Pagination or Media Count:

15.0

Abstract:

The overall project goal was to understand and optimize electrode processes in nonflammable ionic liquid electrolytes for application in safe, reliable batteries. For anode development, the nucleation-growth mechanisms and the formation of the solid electrolyte interfaces during lithium and sodium electrodepositions were evaluated. while sodium exhibited classic instantaneous nucleation-growth behavior, lithium electrodeposition consisted of two sequential nucleation-growth steps and was consistent with the substrate electrode surface being heterogeneous towards lithium nucleation. Also, impedance studies confirmed the formation of a solid electrolyte interface at both lithium and sodium electrodeposits however, the interface at sodium was approximately ten times more resistive than the lithium interface. For cathode development, spin- coated vanadium oxide xerogel films were prepared using sequential casting techniques and were seen, using scanning electron microscopy, to possess a layered structure with thin sheets running parallel to the casting surface. Finally, novel ionic liquid-polymer gel electrolytes, composed of a perfluoroanion ionic liquid and a polyvinylidene fluoride hexafluoropropylene, copolymer were developed and characterized during this project. The ionic conductivities of these nonvolatile, nonflammable solid-state electrolytes were measured from room-temperature to 100 deg C and found to increase from Ca. 1 mS cm to Ca. 13 mScm over this temperature range.

Subject Categories:

  • Inorganic Chemistry
  • Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE