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Solubility of Li/sub 2/S in LiF-LiCl-LiBr electrolyte: measurements and calculations

Conference ·
OSTI ID:6458579

High performance lithium-alloy/iron sulfide cells are currently being developed at Argonne National Laboratory and at several industrial firms for electric vehicle propulsion. These cells operate at high temperatures and utilize Li-Al or Li-Si negative electrodes, FeS positive electrodes, and a molten salt electrolyte. In the early work, the molten salt was the LiCl-KCl eutectic (58.2 mol % LiCl-41.8 mol % KCl), but in recent work various electrolyte compositions have been used, i.e., LiCl-rich LiCl--KCl (typically 67 mole % LiCl), LiF-LiCl-KCl, or LiF-LiCl-LiBr (1). The use of these electrolytes requires cell operating temperatures in the range of 703-773 K. As these cells are cycled, it has been shown that, when LiCl-KCl electrolytes were used, local electrolyte compositional changes occurred because of ion transport processes and chemical reactions in the cells. However, despite the temperature or the nature of the electrolyte, iron and lithium sulfide are the final discharge products. Thus, a systematic investigation of the solubility of Li/sub 2/S in a variety of electrolytes containing LiCl as a function of temperature is of technological importance in the development of these cells. We report new solubility measurements of Li/sub 2/S in the LiF-LiCl--LiBr eutectic solution (22 mol %-31 mol %-47 mol %) at 739 and 773 K. The observed increase of Li/sub 2/S solubility as the solvent is changed from LiCl-KCl to LiF-LiCl-LiBr and then to LiF-LiCl is explained in terms of known molten salt theories.

Research Organization:
Argonne National Lab., IL (USA)
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
6458579
Report Number(s):
CONF-830508-9; ON: DE83009592
Country of Publication:
United States
Language:
English