Reduction Of Thionyl Chloride Research Articles

The synthesis of porphyrin and metalporphyrins and their improvement to the property of Li/SOCl2 primary battery

5-Hydroxyphenyl-11,15,20-triphenylporphyrin H2Pp(1), and its six corresponding metalloporphyrins MnPp(2), FePp(3), CoPp(4), NiPp(5), CuPp(6), ZnPp(7) were synthesized and characterized. Their improvements to the Li/SOCl2 battery were tested. The results show that the discharge voltages of the battery catalyzed by 1–5 are increased by approximately 20–120 mV except 6 and 7. And the discharge time is lengthened by 26.7–157.6 s for 1, 2, 5 and 7. The maximum initial discharge voltages of battery in the presence of 1–7 are also increased. It shows that the central metal ion influences the charge transfer process during the reduction of thionyl chloride.

Catalytic activity to lithium-thionylchloride battery of different transitional metal carboxylporphyrins

The 5-(4-carboxylatomethoxy)phenyl-10,15,20-triphenyl porphyrin ( H 2 Pp ) and its transition metal complex (MPp, M = Zn 2+, Co 2+, Ni 2+, Cu 2+) were synthesized and characterized by IR, UV-vis, MS and elementary analysis. Electrocatalytic effects associated with the reduction of thionyl chloride in a lithium/thionyl chloride ( Li / SOCl 2) battery containing H 2 Pp and its transition metal complex (MPp, M = Zn 2+, Co 2+, Ni 2+, Cu 2+) are evaluated by the relative energy of the battery and discharge time. The results indicate that the energy of Li / SOCl 2 battery catalyzed by CuPp and ZnPp is 103.7%, 106.3%, respectively, higher than that of Li / SOCl 2 battery in the absence of the porphyrins. The energy of Li / SOCl 2 battery whose electrolyte contains NiPp and CoPp is similar to that of the cell in the absence of these complexes. It shows that the electronic configuration of the central metal ion influences a charge-transfer process during the reduction of thionyl chloride. With the increasing numbers of d electrons of the central metal ion, the catalytic activity of MPps was enhanced. The ZnPp with electronic configuration d10 of central metal ion exhibits relatively high catalytic activity.

Electrocatalytic Performance of Binuclear Co-Mn Phthalocyanine for the Reduction of Thionyl Chloride

We used cyclic voltammetry to study the electrocatalytic behavior of binuclear Co-Mn phthalocyanine to determine whether binuclear phthalocyanine compounds have better electrocatalytic performance for the reduction of thionyl chloride than the mononuclear phthalocyanine compounds, cobalt phthalocyanine and iron phthalocyanine. Experiments were conducted in 1.5 mol·L-1 LiAlCl4/SOCl2 electrolyte solution and kinetic parameters were calculated to assess the electrocatalytic performance of the planar binuclear Co-Mn. Cyclic voltammograms showed that by comparison to the mononuclear cobalt phthalocyanine and iron phthalocyanine, the binuclear Co-Mn phthalocyanine had better catalytic activity for the reduction of thionyl chloride. The binuclear Co-Mn phthalocyanine increases the SOCl2 reduction potential and current by improving the exchange rate constant of SOCl2 reduction and the diffusion coefficient of SOCl2 on a glassy carbon electrode. Constant-current (10 mA) discharge curves of real ER14250-type Li/SOCl2 cells demonstrated that the binuclear Co-Mn phthalocyanine catalyst, which has better electrocatalytic activity than the mononuclear cobalt phthalocyanine and iron phthalocyanine, can increase the mid-point voltage to 0.3 V at low temperature (-30 ℃) and improve the discharge capacity to about 100 mAh at room temperature (25 ℃).

Synthesis, Structure and Characterization of Schiff Base Metal Complexes and Their Electrochemical Properties of Thionyl Chloride Reduction

AbstractA symmetric tetradentate Schiff base ligand bis(3‐methoxysalicylidene)‐o‐phenylenediamine (H2L) was prepared. A series of transition metal complexes with this Schiff base ligand have been synthesized and structurally characterized by IR and elemental analysis. The catalysis for reduction of thionyl chloride was studied by means of constant resistance discharge. The result shows that [Mn(III)LCl(H2O)]CH3OH and [Co(II)HLCl(H2O)] have a good catalytic activity for the reduction of thionyl chloride, which improves the cell voltage, the rate of discharge, and the lifetime of Li/SOCl2 batteries.

Electrocatalytic effects of thionyl chloride reduction by polymeric Schiff base transition metal(II) complexes

Electrocatalytic effects for the reduction of thionyl chloride in LiAlCl 4/SOCl 2 electrolyte solution containing polymeric Schiff base M(II) (M: Ni and Cu) complexes were evaluated by determining kinetic parameters with cyclic voltammetry at a glassy carbon electrode. The charge transfer process during the reduction of thionyl chloride was affected by the concentration of the catalyst. The catalytic effects were demonstrated from both a shift of the reduction potential for the thionyl chloride in a more positive direction and an increase in peak currents. The reduction of thionyl chloride was found to be diffusion-controlled. Catalytic effects are larger in thionyl chloride solutions containing (PVPS)M(II)(SALPR) rather than in those containing (PVPS)M(II)(SALPE). Such results are opposite to those for monomeric Schiff base complexes. Significant improvements in the cell performance were found in terms of both thermodynamics and kinetic parameters for the thionyl chloride reduction. An exchange rate constant, k o, of 1.62×10 −8 cm/s was found at a bare electrode, while larger values of (4.69–8.18)×10 −8 cm/s were observed at the catalyst-supported glassy carbon electrode.

Studies on electrochemical properties of thionyl chloride reduction by Schiff base metal(II) complexes

Electrocatalytic effects associated with the reduction of thionyl chloride in a LiAlCl 4–SOCl 2 electrolyte solution containing Schiff base metal(II) (metal (M): Co, Ni, Cu and Mn) complexes are evaluated by determining the kinetic parameters for the reactions using cyclic voltammetry at a glassy carbon electrode. The charge-transfer process during the reduction of thionyl chloride is affected by the concentration of the catalyst. Catalytic effects are demonstrated from both a shift in the reduction potential for the thionyl chloride in a more positive direction and an increase in peak currents. The reduction of thionyl chloride is diffusion controlled. Catalytic effects are larger for thionyl chloride solutions containing M(II)(1,5-bis(salicylidene imino) pentane) (M(II)(SALPE)) rather than M(II)(1,3-bis(salicylidene imino) propane) (M(II)(SALPR)). Significant improvements in cell performance are found in terms of the both thermodynamics and kinetic parameters for the thionyl chloride reduction. An exchange rate constant, k 0, of 1.89×10 −8 cm s −1 is found at the bare electrode, while larger values of 2.79×10 −8 to 2.09×10 −6 cm s −1 are observed in the case of the catalyst-supported glassy carbon electrode.

Mass transport and kinetic aspects of thionyl chloride reduction at the platinum microelectrode

The mass transport and electrochemical kinetic characteristics during the electrochemical reduction of thionyl chloride were investigated using a platinum microdisk electrode. Diffusion coefficients and standard rate constants were determined from fast scan cyclic voltammetric, chronoamperometric, and pulse voltammetric measurements. Activation energies of the diffusion process, as well as the electron transfer process, have also been determined. The results indicate that in 0.5 M LiAlCl 4/SOCl 2 solutions the activation energies are much higher than those obtained at higher concentrations.

Catalytic effect of transition metal(II)- N, N′-bis(naphthaldehyde)diimines on reduction of thionyl chloride

A series of transition metal(II) complexes, such as 1,2-bis(naphthylideneimino)ethane [M(II)(NAPET)], 1,3-bis(naphthylideneimino)propane [M(II)(NAPPR)], 1,4-bis(naphthylideneimino)butane [M(II)(NAPBU)] and 1,5-bis(naphthylideneimino)pentane [M(II)(NAPPE)] (M=Co, Cu, Ni), are synthesized. Catalytic effects of these complexes for the reduction of thionyl chloride on a glassy carbon electrode are evaluated by determining kinetic parameters with cyclic voltammetry. The charge transfer process during the reduction of thionyl chloride is affected by the concentration of catalysts. Some tetradentate Schiff base M(II) complexes show catalytic activities for the reduction of thionyl chloride. The catalytic effects are demonstrated from a shift of the reduction potential for thionyl chloride towards a more positive direction and an increase in peak current. Significant improvements in the cell performance have been noted in terms of both thermodynamic and kinetic parameters for the thionyl chloride reduction. An exchange rate constant, k o, of 1.24×10 −8 cm/s was observed at a bare electrode, while larger values of 0.23–1.69×10 −7 cm/s were observed at the catalyst-supported glassy carbon electrode. Thermodynamic and kinetic parameters for thionyl chloride reduction are affected by the chelate ring size of ligands in the metal(II)–Schiff base complexes used as a catalyst.

Photoassisted reduction of thionyl chloride by neodymium, europium, thulium and lutetium diphthalocyanines

Diphthalocyanine complexes of Nd III, EuIII, TmIII and LuIII ( [Pc (−2) Nd IIIPc (−2) ] −, [Pc (−2) EuIIIPc (−2) ] −, [Pc (−2) TmIIIPc (−2) ] − and [Pc (−2) LuIIIPc (−2) ] −, respectively) , undergo one or two-electron oxidation in the presence of thionyl chloride. The oxidation products depend on the concentration of the thionyl chloride. At low concentrations of SOCl2 (<10−4 mol dm−3) one-electron oxidation occurs only upon photolysis, giving the neutral lanthanide diphthalocyanine, Pc (−2) LnPc (−1) , complexes. The Pc (−2) LnPc (−1) species undergo one-electron photooxidation to the [Pc (−1) LnPc (−1) ] + in dichloromethane and in the presence of SOCl2. At large concentrations of SOCl2 (>10−2 mol dm−3) , two electron oxidation of the [Pc (−2) LnPc (−2) ] − species directly to [Pc (−1) LnPc (−1) ] + occurs.

Spectroelectrochemical Studies on the Reduction of Thionyl Chloride

The electrochemical reduction of thionyl chloride in dimethyl sulfoxide and of the thionyl chloride‐lithium tetrachloroaluminate system has been studied using spectroelectrochemical techniques. Results indicate that the reduction mechanism of in the solution is essentially the same as that in DMSO. The key intermediate species in this reduction is shown to be , which is produced upon reduction of by a one‐electron transfer, followed by the dechloridation process. This species then undergoes a series of following reactions to produce the final reduction products, S and , via other intermediates such as and . At very negative potentials, reduction products of S and are shown to be produced.

Electrochemical Reduction of Thionyl Chloride Studied by Cyclic Voltammetry, Chronocoulometry, and Chronoamperometry

Electrochemical reduction of thionyl chloride has been studied at a molybdenum electrode employing cyclic voltammetric, chronocoulometric, and chronoamperometric techniques. The charge transfer process is affected strongly by the film formed on the electrode surface during the reduction. The exchange rate constants, , of the order of 10−6 cm/s were observed at fresh electrodes, whereas much smaller constants of about 10−10 cm/s were observed at film‐covered electrodes. The activation energy at the film‐covered electrode for the electron‐transfer reaction was dependent on whether the measurements were made with the cell temperature increased or decreased. Chronocoulometric results indicate that the film formation takes place at the electrode surface during the electrochemical reduction of thionyl chloride. The thickness of this film estimated to be about 10−5 cm from chronocoulometric and chronoamperometric experiments. Different diffusion behaviors were observed in three different time zones in chronoamperometric experiments.

Influence of macrocyclic compounds on the electrochemical reduction of thionyl chloride at glassy carbon cathodes

The specific features of electrochemical reduction of thionyl chloride were studied on a smooth glassy carbon electrode in the presence of tetraphenylporphyrins (TPP) or tetra( p-methoxyphenyl)porphyrins (TMPP) of copper, manganese, iron, nickel, cobalt and also of metal-free TPP and TMPP. In the presence of metal-free porphyrin and its metallo complexes the potential of the maximum on voltammograms shifts markedly in the positive direction. Introduction into the solution of FeTPP, CoTPP and NiTPP leads to an increase of the maximum current on cyclic voltammograms. The amount of electricity necessary for electrode passivation also changes thereby. This indicates that the role of porphyrins in the SOCl 2 electroreduction is due both to electrocatalytic action and to changing the electrode passivation conditions. With the use of a combination of spectroscopic methods (electron absorption and ESR spectra) it has been found that thionyl chloride interacts chemically with the porphyrins. These chemical interaction products act as catalysts of SOCl 2 electroreduction.

Two-electron oxidation of cobalt phthalocyanines by thionyl chloride. Implications for lithium/thionyl chloride batteries

Abstract : Cyclic voltammetry, DPV and electronic spectroscopy are used to study the reaction between thionyl chloride and cobalt phthalocyanine. SOC12 reacts with (Co(I)Tn Pc(2-)) and Co(II)Tn Pc(2-) to give two-electron oxidized species. Implications for Li/SOC12 batteries are discussed. Thionyl chloride also forms a mono SOC12 adduct with Co(II)TnPc(2-). Driving forces (Delta E values) have been calculated for CoTnPc comproportionation and CoTnPc + SOC12 reactions. Rest potential measurements of a Li/SOC12 cells show that addition of A1C13 stabilizes the LiC1 product as LiA1C14. A catalytic two-electron mechanism is indicated for the reduction of thionyl chloride in a Li/SOC12/(CoTnPc,C) battery. Keywords: Electric batteries; Phthalocyanine; Lithium battery, Thionyl chloride; Two electron oxidation; Aluminum; Cobalt.

Estimation of Electrode Kinetic Parameters of the Lithium/Thionyl Chloride Cell Using a Mathematical Model

A one‐dimensional mathematical model for the lithium/thionyl chloride primary cell is used in conjunction with a parameter estimation technique, in order to estimate the electrode kinetic parameters of this electrochemical system. The electrode kinetic parameters include the anodic transfer coefficient and exchange current density of the lithium oxidation, and ; the cathodic transfer coefficient and the effective exchange current density of the thionyl chloride reduction, and , and a morphology parameter, ξ. The parameter estimation is performed on simulated data first in order to gain confidence in the method. Data reported in the literature for a high‐rate discharge of an experimental lithium/thionyl chloride cell is used for an analysis.

The kinetics of the reduction of thionyl chloride

The rate, reaction mechanisms, and the catalysis of the electrochemical reduction of thionyl chloride from anhydrous media, are discussed. Voltammetric measurements at stationary plane and rotated disc electrodes, using glassy carbon, graphite, or metal electrodes, have been made using thionyl chloride alone or at high dilution in supporting electrolytes. Porous carbon electrodes have been used to study stoichiometry and to determine how electrolyte concentration affects capacity. Chemical analysis of cells after partial or complete discharge has established that without catalysis, the products are sulfur, sulfur dioxide, and lithium chloride. In both acid and neutral electrolytes, the reduction behaves as though it were diffusion controlled, whether the cathodes are porous carbon electrodes or rotated disc electrodes. The mechanism of the reduction likely involves several electrochemical and chemical steps, proceeding through unstable and metastable intermediates. The reduction is irreversible because the species initially produced rapidly decomposes. On decomposition, one of the intermediates produces thionyl chloride. The overpotential at either porous or nonporous electrodes can be lowered, and the capacity of porous electrodes increased, by high surface area carbons or by the use of catalysts. It is not known whether catalysts change the overall discharge stoichiometry. In basic electrolytes, the first step in the reduction on a carbon surface appears to be first order with respect to the concentration of chloride ion and to involve only one electron. The species produced by the initial reduction is stabilized by chloride ion. As the chloride ion concentration is lowered, the initial reduction begins to involve more than one electron.

Macrokinetic study of thionyl chloride reduction on porous carbon electrodes

Macrokinetic study of thionyl chloride reduction on porous carbon electrodes

Studies of the reduction of thionyl chloride in dimethyl formamide using microdisc electrodes

The reduction of thionyl chloride (SOCl 2) in dimethyl formamide (DMF) was studied using Pt microdisc electrodes. The total number of electrons involved in this reduction was calculated from the experimental limiting current plateau on the steady-state polarization curves and found to be two. A Tafel plot with a slope very close to 120 mV/decade was also obtained from the steady-state polarization curve of reduction. By analysing the Tafel plot, it is clear that the transfer of the first electron in SOCl 2 reduction is totally irreversible, with α very close to 0.5. Cyclic voltammograms demonstrated that the transfer of the second electron is comparatively rapid, and a product of the two-electron reduction of thionyl chloride, probably sulphur, could be reduced further, to some extent.

Investigation of SOCl2 Reduction by Cyclic Voltammetry and AC Impedance Measurements

Cyclic voltammetry and ac impedance measurements, covering the range 10−3–104 Hz, were employed to investigate the reduction of thionyl chloride on glassy carbon surfaces and to determine the associated elementary processes. The quasi‐exchange current density of the electroreduction of is and becomes larger in the presence of dissolved chlorine. Also, in the presence of , the rest potential shifts to more positive values. At low overpotentials, the reduction of is kinetically controlled. However, as the overpotentials are increased, a transition to mass‐transport control occurs, even before the onset of passivation at +2.7V. The rate of mass transport is governed by the thickness and quality of the film.

The Mechanisms of Thionyl Chloride Reduction at Solid Electrodes

An experimental technique has been devised which allows in situ sampling of electrolyte from a functioning cell, followed by rapid FTIR analysis for soluble reaction products. Disulfur monoxide is observed as an intermediate discharge product. The half‐life of is estimated to be about 20 min. The presence of is consistent with sulfur chemistry, as well as the accepted stoichiometry of the battery system. A possible safety hazard for low temperature discharges of cells is identified.

On the Mechanism of Thionyl Chloride Reduction

not Available.