Room temperature inorganic ``quasi-molten salts`` as alkali-metal electrolytes
- Arizona State Univ., Tempe, AZ (United States). Dept. of Chemistry
Room temperature inorganic liquids of high ionic conductivity have been prepared by reacting Lewis acid AlCl with sulfonyl chlorides. The mechanism is not clear at this time since a crystal structure study of the 1:1 complex with CH{sub 3}SO{sub 2}Cl (T{sub m} = 30 C) is not consistent with a simple chloride transfer to create AlClO{sub 4}{sup {minus}} anions. The liquid is in a state somewhere between ionic and molecular. A new term quasi-molten salt is adopted to describe this state. A comparably conducting liquid can be made using BCL{sub 3} in place of AlCl{sub 3}. Unlike their organic counterparts based on ammonium cations (e.g., pyridinium or imidazolium) which reduce in the presence of alkali metals, this inorganic class of cation shows great stability against electrochemical reduction (ca. {minus}1.0 V vs. Li{sup +}/Li), with the useful consequence that reversible lithium and sodium metal deposition/stripping can be supported. The electrochemical window for these quasi-salts with AlCl{sub 3} ranges up to 5.0 V, and their room temperature conductivities exceed 10{sup {minus}4} S/cm. They dissolve lithium and sodium tetrachloroaluminates up to mole fraction {approximately} 0.6 at 100 C and intermediate compositions are permanently stable at ambient. The resultant lithium or sodium salt solutions exhibit electrochemical windows of 4.5--5.0 V vs. Li{sup +}/Li or Na{sup +}/Na and show room temperature conductivities of 10{sup {minus}3.0}--10{sup {minus}2.5} S/cm. In preliminary charge/discharge tests, the cell Li/``quasi-ionic liquid electrolyte``/Li{sub 1+x}Mn{sub 2}O{sub 4} showed a discharge capacity of ca. 110 mAh/(g of cathode) and sustained 80% of the initial capacity after 60 cycles, indicating that these quasi-molten salt-based electrolytes are promising candidates for alkali-metal batteries.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-89ER45398
- OSTI ID:
- 428164
- Journal Information:
- Journal of the Electrochemical Society, Vol. 143, Issue 11; Other Information: PBD: Nov 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Electrochemical study of new room temperature, molten salt electrolytes. DE FG 02-97ER14798 Final report
Spectroscopic and electrochemical studies of europium(III) chloride in aluminum chloride-1-methyl-3-ethylimidazolium chloride room temperature molten salts