The Effect of Polyvinyl Chloride and Fe on Film Growth and Voltage Delay in SOCl2 Electrolytes

Boyd, Jean W.

doi:10.1149/1.2100402

Cited by 20 publications

(14 citation statements)

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“…Boyd 25 examined the LiCl film by SEM. He found that the film is composed of two layers: A thin layer of small crystals of 2000-5000 nm size (about 10 x bigger than found by Peled and Yamin 4 ) on top of the Li surface and a thicker layer of large crystals on top of them.…”

Section: Literature Surveymentioning

confidence: 99%

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Properties and Structure of the LiCl-films on Lithium Anodes in Liquid Cathodes

Mogensen

Hennesø²

2016

ACSi

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Lithium anodes passivated by LiCl layers in different types of liquid cathodes (catholytes) based on LiAlCl 4 in SOCl 2 or SO 2 have been studied by means of impedance spectroscopy. The impedance spectra have been fitted with two equivalent circuits using a nonlinear least squares fit program. Information about the ionic conductivity and the structure of the layers has been extracted. A new physical description, which is able to explain the circuit parameters, is proposed. It assumes that the LiCl-layer contains a large number of narrow tunnels and cracks filled with liquid catholyte. It is explained why such tunnels probably are formed, and for a typical case it is shown that tunnels associated with most of the LiCl grain boundaries of the fine crystalline layer near the Li surface are requested in order to explain the impedance response. The LiCl production rate and through this, the growth rate of the LiCl-layer, is limited by the electron conductivity of the layer. Micro-calorimetry data parallel with impedance spectra are used for determination of the electron conductivity of the LiCl-layer.

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Section: Literature Surveymentioning

confidence: 99%

“…Based on a number of SEM studies 1,4,12,25,26 the porosity of the secondary layer is estimated to be no more than a few percent, say max 5% and more probably around 1%. This makes it very difficult to accept that it should not contribute to the electrical response.…”

Section: Literature Surveymentioning

confidence: 99%

Properties and Structure of the LiCl-films on Lithium Anodes in Liquid Cathodes

Mogensen

Hennesø²

2016

ACSi

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“…The rate of secondary film growth strongly depends on temperature, 20 electrolyte concentration, 14,20 and on the type of electrolyte additives. 15,21,22 For a 1.5 M LiAlCl 4 solution without additives and at ambient temperature, one finds on average the following values of the secondary-film thickness 3,7,8,15 : about 1 m after 1 day, 10 m after 1 month, and 20 m after 1 year of storage.Obviously, a significant degree of understanding the passivation processes in the Li/SOCl 2 system has been achieved. A careful survey of the mentioned measurements and models reveals, however, that some basic questions have remained open.…”

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Time Evolution of the Impedance Response of a Passive Film: A Simple Application to the Li / SOCl2 system

Gaberšček

Pejovnik

1999

J. Electrochem. Soc.

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In the 1970s and the beginning of the 1980s the passive film formed on lithium in SOCl 2 -based solutions was a subject of numerous investigations, primarily because it was regarded as a cause of the so-called voltage-delay phenomenon, which, at that time, was a major drawback of the Li/SOCl 2 batteries. To many researchers, however, the system remained interesting even after the voltage-delay problem had been solved (by different electrolyte additives and/or modifications). The persisting interest in this particular lithium system can be explained by several facts: (i) in this system the lithium passive film has a simple composition (basically LiCl), (ii) the electrochemical properties (e.g., the impedance response) of this film have been considered simple to model, (iii) the film electrochemical properties show big and hence easy-to-measure variation with storage time, and (iv) during investigation of the "voltage-delay phenomenon," a huge amount of data using many different techniques were gathered, many of which have remained unexplained or even in direct contradiction. The present paper is an attempt to clarify several of these inconsistencies, particularly those concerning the impedance spectroscopy and related measurements of the passive film.The techniques used to study the spontaneous nucleation and growth of the passive film under consideration have been the potential sweep and step (or pulse) experiments, 1-5 impedance spectroscopy measurements, 6-11 microcalorimetry, 9,12 scanning electron microscopy (SEM), 7,10,13-15 measurements of weight gain of a Li electrode during storage in the electrolyte, 16 and the isotope method. 8 With regard to the kinetics of the initial coverage of the lithium surface with a passive film, most authors have given qualitative estimations such as, "Immediately 4,8,17 after its contact with the electrolyte, the Li surface is covered with a thin passivating film." A more quantitative result was obtained by Hedges et al. 2 who, in microelectrode studies of the Li/Li ϩ couple, found that "a period on open circuit of 100 s is long enough for the formation of a film of thickness sufficient to inhibit corrosion..." (In that experiment 1.7 M solution of LiAlCl 4 in SOCl 2 was used.) Even more specific results were obtained by Moshtev et al., 3 who found it possible to determine the moment when the lithium surface was 100% covered with a thin protective film using the galvanostatic pulse technique. Although not explicitly given in Ref. 3, one may recalculate from Fig. 2 and 3 of that paper that the coverage was completed about 30-40 min after lithium had been exposed to the electrolyte. At that moment the calculated average film thickness was 3.2 nm. Moshtev et al. 3 also reported that after the Li surface had been covered, the dense primary film grew thicker with storage time to reach a thickness of about 10-30 nm within a period of 6 h. Similar results were obtained by Holleck and Brady, 4 who reported that the primary film reached a thickness of 30 nm within 1-20 h after the ex...

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“…[5][6][7][8][9][10][11][12] This surface layer is responsible for a voltage delay effect, which results in a cell voltage drop during the initial discharge. [13][14][15][16][17] Improvements in the performance of the Li/SOC12 cell have been sought by the use of interhalogen compounds as additives. Kreh] and Liang, 18 Liang et al, 19 and Murphy et al 2o reported that addition of BrC1 to the Li/SOC12 resulted in a higher open-circuit voltage, higher capacity, better low temperature discharge performance, and some improved safety features.…”

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Impedance Spectroscopy as a Nondestructive Health Interrogation Tool for Lithium‐BCX Cells

Popov¹,

Zhang²,

Darcy

et al. 1993

J. Electrochem. Soc.

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The objective of this investigation was to study the growth of thick passivating layers on the Li anode in Li/BCX false(normalLi/SOCl2+normalBrClfalse) cells which were stored for a period of 3 years. Impedance spectroscopy and equivalent circuit models were used to determine characterizing parameters for these cells. The equivalent circuit used for virgin cells includes a faradic contribution and diffusion of the electroactive species. The equivalent circuit for batteries stored 1 or 2 years includes the impedance of a metal/passive film interface, the resistance of the film, and the impedance of the passivating film/electrolyte interface. The equivalent circuit used for batteries stored for 3 years accounts for cathodic contributions in the overall impedance spectrum.

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The Effect of Polyvinyl Chloride and Fe on Film Growth and Voltage Delay in SOCl2 Electrolytes

Cited by 20 publications

References 1 publication

Properties and Structure of the LiCl-films on Lithium Anodes in Liquid Cathodes

Properties and Structure of the LiCl-films on Lithium Anodes in Liquid Cathodes

Time Evolution of the Impedance Response of a Passive Film: A Simple Application to the Li / SOCl2 system

Impedance Spectroscopy as a Nondestructive Health Interrogation Tool for Lithium‐BCX Cells

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