Electrochemical Studies of Tetrabutylammonium Electrolytes at Carbon Cathodes in Sulfuryl Chloride Cells

Walker, Charles W.; Binder, Michael; Wade, William L.; Gilman, S.

doi:10.1149/1.2113677

Cited by 2 publications

(1 citation statement)

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“…In SO2C12, LiA1C14 2M electrolyte, when the reduction takes place at a platinum electrode already passivated by LiC1 film due to SO2C12 reduction, no process appears in a second cathodic sweep unless an anodic current is applied to the system so that a potential of 4.4 V is reached. In this step, LiC1 is removed by the A1C13, and Cle is formed in situ (23).…”

Section: Table I Comparison Of the Evolution Ofmentioning

confidence: 99%

The Impedance of the Cathodic Electrode in SO 2Cl2 ‐ Solvate Mixed Electrolytes

Lojou¹,

Messina²,

Chenebault³

et al. 1991

J. Electrochem. Soc.

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Impedance measurements were carried out at a platinum electrode in SQC12-solvate mixed electrolytes. Impedance loci were recorded over a range of frequencies at several surimposed potentials. The results confirm the growth of a passivating film as the reduction proceeds. Great differences for the texture of this film were obtained between SO2C12 electrolyte and SO2C12-solvate mixed electrolytes, and it was possible in some cases to remove the passivating film by applying low anodic potentials to the electrode.Lithium/liquid cathode systems have received considerable interest in recent years for space and military applications due to their high energy and power densities (1). Among these systems, LiA1C14, 3SO2 solvate has been used for secondary Li/SO2 cells (2, 3) or for solid cathode systems (4). A recent work (5), has shown that this electrolyte was also suitable for fundamental studies of the reduction of SO2C12 because of its stability over a large range of potentials. Furthermore, using the solvate provided improvements in discharge characteristics of Li/SO2C12 cells due to the high solvate conductivity over a large range of temperatures (6).The generally accepted mechanism for SO2C12 reduction can be written as follows SO2Cl2 + 2e ---> SO2 + 2C1As solid LiC1 precipitated during discharge (7), many studies have dealt with optimal solutions to the cathode polarization problems (8-10). However, a better understanding of the reaction mechanisms is necessary, especially when LiA1C14, 3SO2 solvate is used as a cosolvent in SO2Cl2, in order to improve the performance of high rate cells.A previous investigation, devoted to SO2C12 reduction in the solvate, emphasized that the reduction was controlled by a diffusion process through a buildup of LiC1 (5). At this time, two hypothesis concerning the rate-determining step of the reduction were proposed (11): (i) either the diffusion of SO2C12 occurred through a dense layer of LiC1, with a value of the diffusion coefficient of 10 10 cm 2 . s-~ (it) or the LiC1 film presented a low porosity and diffusion occurred in the grain boundaries.We supposed the latter was more reasonable since the formation of SO2 during the reduction could promote LiC1 solubility at the electrode/electrolyte interface (12)(13)(14).This paper deals with the formation of the passivating film during SO2C12 reduction at a platinum microelectrode. This growth is followed by the impedance method which enables one to compare the texture of the film formed in both SO2C12, LiA1C14 2M and SO2C12-solvate mixed electrolytes. The possibility of removing the passivating film by applying anodic potentials to the cathodic collector is then examined. Finally, the reoxidation process of SO2C12 in the different electrolytes are compared using an intensiostatic method. Experimental ProcedureElectrolytes.--All experiments were carried out in an argon-filled glove box at a temperature of 20~ * Electrochemical Society Active Member.A solvate of composition 3SO~, LiA1C14, which presents a conductivity of 92.10 -3 ~ ~ 9 ...

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Section: Table I Comparison Of the Evolution Ofmentioning

confidence: 99%