Viscosity and conductance studies in ethylene carbonate at 40°C

Abstract

Viscometric measurements of numerous electrolytes in ethylene carbonate (EC) at 40°C are reported. B-coefficients, obtained by the Jones-Dole equation, are compared with those relative to other dipolar aprotic solvents. Conductometric measurements in EC for some salts are also reported, so that these, together with the viscometric data, permit a more complete analysis of ions o lvent interaction,We are systematically studying the transport properties of electrolytes in dipolar aprotic solvents to obtain information on the behaviour of ions in this class of solvents. We have previously reported viscometric measurements in sulpholane (TMS)' and hexamethylphosphotriamide (HMPT).' In the present paper we have extended our studies to ethylene carbonate (EC). This solvent possesses a higher dielectric constant than water and a high dipolar moment (E = 90.36 and p = 4.87 D It has been used as solvent because it possesses these properties to realize high energy nonaqueous batteries? Information in the literature on solute-solvent interactions in EC has been obtained through measurements of osmotic coefficients and activity and conductometric measurem e n t~.~ In order to be able to compare the behaviour of a wider variety of ions in EC, both viscometric and further conductometric measurements have been carried out in this solvent.at 40°C) and is slightly structured.4* EXPERIMENTAL EC was distilled three times under reduced pressure. The method of salt purification, ihe apparatus and the method used for measuring viscosities, densities and conductances of solutions have already been described.' * The density, viscosity and specific conductance of EC at 40°C were : 1.320 99+ 0.000 04 g ~m -~, (1.925+0.002)x Viscosity and density measurements were carried out at 40+_ O.Ol"C, the conductonietric ones at 40.000+ 0.002"C.The viscometer was calibrated with water and aqueous solutions of sucrose (Fisher certified ACS) by means of the equation : kg m-l s-l and 1 x lo-' S cm-', respectively.where q is the absolute viscosity, p is the density and t is the flow time of the calibrating solution. The values of the characteristic viscometer constants K and L are 0.004 742xThe conductance cell was of the Erlenmeyer type as described by Dagget, Bair and Kraus. m2 s -~ and 2.315 x m2, respectively.Its constant was determined at 25°C by measuring the conductance of aqueous potassium chloride solutions, as suggested by Ying-Chech Chiu and FUOSS." The cell constant was 0.216 54+0.000 02 cm-1. Previous experience l 1 indicates that the cell constant does not significantly change between 25 and 40°C.The viscosity of the solutions was calculated by eqn (1).

What is the fundamental ion-specific series for anions and cations? Ion specificity in standard partial molar volumes of electrolytes and electrostriction in water and non-aqueous solvents

“…Data from the CRC Handbook of Chemistry and Physics, 64 except for: b Easteal and Woolf; 65 c Easteal and Woolf; 66 d Marcus and Hefter; 67 e Chernyak; 68 f Petrella and Sacco; 69 g Naejus et al ; 70 h Barthel et al . 71 …”

Conductivity and Viscosity of PC-DEC and PC-EC Solutions of LiBF[sub 4]

“…[6][7][8]11,[20][21][22] Accordingly, the Bjerrum critical distance for univalent ions exhibited a near independence on but a strong dependency on w, rising steadily as fell with the change of w, indicating a corresponding change in ion association. 3,4,6,7,9,11,20,21,[23][24][25] Furthermore, the of (LiPF 6 ) m -PC 1Ϫw DEC w and (LiPF 6 ) m -PC 1Ϫw EC w solutions rose with m and fell with w of DEC but rose with w of EC, and the of (LiPF 6 ) m -PC 1Ϫw DEC w peaked in both m and w thus forming a dome in the mw coordinates, but the of (LiPF 6 ) m -PC 1Ϫw EC w peaked only in m thus forming an arch. 3,4,6,7,9,11,20,21,[23][24][25] Furthermore, the of (LiPF 6 ) m -PC 1Ϫw DEC w and (LiPF 6 ) m -PC 1Ϫw EC w solutions rose with m and fell with w of DEC but rose with w of EC, and the of (LiPF 6 ) m -PC 1Ϫw DEC w peaked in both m and w thus forming a dome in the mw coordinates, but the of (LiPF 6 ) m -PC 1Ϫw EC w peaked only in m thus forming an arch.…”

Conductivity and Viscosity of PC-DEC and PC-EC Solutions of LiBOB

“…This equation is also plotted as a T g surface in the mw-coordinates as the insert in the figure, describing a simple surface slanting down from the high-corner of high m and w toward the low-corner of low m and w. It is thus clear that the addition of LiBOB in PC 1Ϫw EC w solvent continuously raised of the resulting solution, a phenomenon observed in many Journal of The Electrochemical Society, 152 ͑1͒ A132-A140 ͑2005͒ A134 other electrolytes. 1,6,9,13,[22][23][24] It also appears that the rise of T g due to the addition of salt was independent of that due to the change of solvent composition, which is most clearly seen in the absence of a cross-product term in the fitting function of Eq. 1.…”

“…4 The of the solvents has been estimated by measuring their glass transition temperature T g , and found to fall steadily with w in PC 1Ϫw DEC w but rise in PC 1Ϫw EC w 4 ͑ of DEC, PC, and EC at 40°C: 0.622, 1.91, and 1.93 mPa s 12,18 ͒, as would normally be expected between similar liquids. 4,6,8,9,11,13,19,[22][23][24] Furthermore, the of (LiPF 6 ) m -PC 1Ϫw DEC w , (LiPF 6 ) m -PC 1Ϫw EC w , (LiBF 4 ) m -PC 1Ϫw DEC w , and (LiBF 4 ) m -PC 1Ϫw EC w solutions has been found to rise with m and fall with w of DEC but rise with w of EC.…”

“…4 The of the solvents has been estimated by measuring their glass transition temperature T g , and found to fall steadily with w in PC 1Ϫw DEC w but rise in PC 1Ϫw EC w 4 ͑ of DEC, PC, and EC at 40°C: 0.622, 1.91, and 1.93 mPa s 12,18 ͒, as would normally be expected between similar liquids. 4,6,8,9,11,13,19,[22][23][24] Furthermore, the of (LiPF 6 ) m -PC 1Ϫw DEC w , (LiPF 6 ) m -PC 1Ϫw EC w , (LiBF 4 ) m -PC 1Ϫw DEC w , and (LiBF 4 ) m -PC 1Ϫw EC w solutions has been found to rise with m and fall with w of DEC but rise with w of EC.1,2 has been found to peak in both m and w for (LiPF 6 ) m -PC 1Ϫw DEC w and (LiBF 4 ) m -PC 1Ϫw DEC w thus forming a dome in the mw-coordinates but only in m for (LiPF 6 ) m -PC 1Ϫw EC w and (LiBF 4 ) m -PC 1Ϫw EC w thus forming an arch.1,2 As is lowered, these surfaces lower their heights and shift their positions in the direction of low .1,2,5 This series of investigation was continued with the work to be presented here, in which (LiBOB) m -PC 1Ϫw DEC w and (LiBOB) m -PC 1Ϫw EC w solutions were studied for their and . The choice for these materials was a result of the strong interest in and the wide use of these three lithium salts * Electrochemical Society Active Member.…”