Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10567379 | Journal of Power Sources | 2005 | 6 Pages |
Abstract
Two hydrophobic ionic liquids (room temperature molten salts) based on 1-butyl-3-methylimidazolium cation (BMI+), BMI+PF6â and BMI+Tf2Nâ, were used in developing a highly efficient lithium anode system for lithium/seawater batteries. The lithium anode system was composed of lithium metal/ionic liquid/Celgard membrane. Both BMI+PF6âand BMI+Tf2Nâ maintained high apparent anodic efficiency (up to 100%) under potentiostatic polarization (at +0.5Â V versus open-circuit potential (OCP)) in a 3% NaCl solution. Eventually, traces of water contaminated the ionic liquid and a bilayer film (LiH and LiOH) on the lithium surface was formed, decreasing the rate of lithium anodic reaction and hence the discharge current density. BMI+Tf2Nâ prevented traces of water from reaching the lithium metal surface longer than BMI+PF6â (60Â h versus 7Â h). However, BMI+PF6â was better than BMI+Tf2Nâ in keeping a constant current density (â¼0.2Â mAÂ cmâ2) before the traces of water contaminated the lithium surface due to the non-reactivity of BMI+PF6â with the lithium metal that kept the bare lithium surface. During the discharge process, BMI+PF6â and BMI+Tf2Nâ acted as ion transport media of Li+, Clâ, OHâ and H2O, but did not react with them because of the excellent chemical stability, high conductivity, and high hydrophobicity of these two ionic liquids. Both BMI+PF6â and BMI+Tf2Nâ gels were tentative approaches used to delay the traces of water coming in contact with the lithium surface.
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Authors
Yancheng Zhang, Mirna Urquidi-Macdonald,