Solubility of Lithium Salts Formed on the Lithium-Ion Battery Negative Electrode Surface in Organic Solvents
Year: 2009
Type: article
Abstract: The solubility of lithium salts in dimethyl carbonate ͑DMC͒ found in solid electrolyte interface ͑SEI͒ films was determined.The salt-DMC solutions evaporated, and the salts were transferred into water for ion conductivity measurements.The salts examined included lithium carbonate ͑Li 2 CO 3 ͒, lithium oxalate ͓͑LiCO 2 ͒ 2 ͔, lithium fluoride ͑LiF͒, lithium hydroxide ͑LiOH͒, lithium methyl carbonate ͑LiOCO 2 CH 3 ͒, and lithium ethyl carbonate ͑LiOCO 2 C 2 H 5 ͒.The salt molarity in DMC ranged from 9.6 ϫ 10 -4 mol L -1 ͑LiOCO 2 CH 3 ͒ to 9 ϫ 10 -5 mol L -1 ͑Li 2 CO 3 ͒ in the order of LiOCO 2 CH 3 Ͼ LiOCO 2 C 2 H 5 Ͼ LiOH Ͼ LiF Ͼ ͑LiCO 2 ͒ 2 Ͼ Li 2 CO 3 .X-ray photoelectron spectroscopy measurements on SEI films on the surface of the negative electrode taken from a commercial battery after soaking in DMC for 1 h suggested that the films can dissolve.Separately, the heat of dissolution of the salts was calculated from computer simulations for the same salts, including lithium oxide ͑Li 2 O͒, lithium methoxide ͑LiOCH 3 ͒, and dilithium ethylene glycol dicarbonate ͓͑CH 2 OCO 2 Li͒ 2 :LiEDC͔ in both DMC and ethylene carbonate ͑EC͒.The results from the computer simulations suggested that the order in which the salt was likely to dissolve in both DMC and EC was LiEDCThis order agreed with the experiment in DMC within the experimental error.Both experiment and computer simulations showed that the organic salts are more likely to dissolve in DMC than the inorganic salts.The calculations also predicted that the salts dissolve more likely in EC than in DMC in general.Moreover, the results from the study were used to discuss the capacity fading mechanism during the storage of lithium-ion batteries.
DOI: 10.1149/1.3239850
Institutions: BIOVIA, General Motors (United States), University of Michigan
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
Funder: University of Michigan
OpenAlex ID: W1976095671