Mass‐Transport Properties of Lithium Surface Layers Formed in Sulfolane‐Based Electrolytes

Abstract

q ABSTRACTThe kinetic and morphological properties of the surface layers formed on lithium electrode in different sulfolanebased electrolytes have been investigated. Application of the impedance theory of the dilute binary electrolyte has allowed a determination of characteristic parameters of the surface layers, such as their cationic transference numbers, salt diffusion coefficients, and ionic concentrations. The values obtained for these parameters have demonstrated that the surface layers behave similarly to their parent liquid electrolytes but with much lower ionic concentrations. In addition, this study has shown that satisfactory cycling performances can be obtained when the values of the characteristic parameters of the layers are close to those of the parent electrolytes. Supplementary tests based on the evaluation of the layer conductivity, the Warburg constant, and the limiting current density, have been proposed for the selection of appropriate organic electrolytes and cycling procedures to be used in secondary lithium batteries.Cycling efficiency measurements.---To avoid excessive cycling durations, the lithium cylinders were rep]aced by

Nonaqueous Electrolytes with Advances in Solvents

“…Since lone-pair electrons on the sulfur atoms are easy to oxidize (low IP), there are no recent uses for use in batteries. Sulfolane (TMS) is the most studied sulfur-containing organic solvent for lithium [ 150 ] and lithium-ion [ 151 ] cells. Since sulfolane is a solid at room temperature, like EC, it is often mixed with low-viscosity solvents to make electrolyte solutions.…”

Accurate Characterization of Ion Transport Properties in Binary Symmetric Electrolytes Using In Situ NMR Imaging and Inverse Modeling

“…There exist several approaches to measuring transference numbers, such as Hittorf’s, moving boundary, electromotive force, galvanostatic polarization, electrophoretic nuclear magnetic resonance (ENMR), and electrical ac impedance methods . While each approach has advantages and disadvantages, the various methods often yield rather different results at salt concentrations of practical interest. , The most common cause for such discrepancies is the extensive ion association existing at high salt concentrations.…”

Impedance of the Li Electrode in Li / Li x MnO2 Accumulators at Open‐Circuit Voltage

“…6 Several authors have shown that all the electrolytes appropriate for application in Li accumulators can be decomposed at the very negative potential of the Li. According to Koch, 17 THF and 2MeTHF decomposition can involve three competing reactions Reduction: Li + THF ---> [THF] -Li + -~ ring-opening products [3] Metallation: LiH + THF --+ [THF] -Li § -~ ring opening products [4] Proton abstraction: B-H + 2Li ---> Li*B + LiH, Li+B + THF ---> B -H + [THF] , Li § ring opening products [5] A decomposition scheme of the PC and EC by Li recently was proposed by Aurbach et al 18 Li § + e -+ [PC]Li § + Li § + e --> Li2CO3 + H2C-CH-CH3 [6] EC + Li + + e -+ [EC]Li + + Li § + e --> Li2CO3 + H3C-CH3 [7] Additionally, LiAsF~ also can be reduced on the Li surface LiAsF6 + 2Li --> AsF3 + 3LiF [8] AsF3 also can be involved in reactions with some of the products of the initial reactions 4-7.…”