JPH06150909A - Manufacture of polymer electrode - Google Patents

Abstract

PURPOSE:To provide an electrode generating a less extent of capacity deterioration due to charging and discharging processes by mixing a solution containing dissolved disulfide compound monomer with a conductive material, and then polymerizing the monomer in the mixture. CONSTITUTION:A solution containing a dissolved disulfide compound monomer is evenly mixed with a conductive material. Iodine or an oxidant such as potassium ferricyanide is added to a dispersion solution so prepared, thereby polymerizing the disulfide compound monomer. Then, a resulting deposit is washed, filtrated and dried, thereby manufacturing a polymer electrode comprising the composite material of the polymer of the disulfide compound and the conductive material. In this case, the disulfide compound monomer may be oxidized and polymerized by electrolyzing the dispersion solution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polymer electrode used in electrochemical devices such as batteries, electric double layer capacitors and electrochromic display devices. More specifically, the sulfur-sulfur bond is cleaved by electrolytic reduction to form a sulfur-metal ion (including proton) bond, and the sulfur-metal ion bond is replaced by the original sulfur-
The present invention relates to a method for producing a polymer electrode containing an organic sulfur compound that regenerates a sulfur bond (hereinafter referred to as a disulfide compound) as a main component.

[0002]

2. Description of the Related Art Disulfide compounds are known as organic materials which can be expected to have high energy density, and are disclosed in US Pat. No. 4,833,048.
No. proposed for disulfide. The simplest is R-
It is represented as S-S-R (R is an aliphatic or aromatic organic group, and S is sulfur). The S—S bond is cleaved (depolymerized) by electrolytic reduction, and R—S ⁻ · with the cation (M ⁺ ) in the electrolytic bath.
This produces a salt represented by M ⁺ . This salt returns to the original R-S-S-R by electrolytic oxidation (polymerization). A metal-sulfur secondary battery in which a metal M that supplies and captures a cation (M ⁺ ) and a disulfide compound is combined is proposed in the above-mentioned US patent. This metal-sulfur secondary battery has 1
Energy density of 50Wh / Kg or more, which is comparable to or higher than that of ordinary secondary batteries, can be expected.

[0003]

DISCLOSURE OF THE INVENTION Since the disulfide compound itself is poor in electronic conductivity, when it is used for an electrode of a battery or the like, the inventors of US Pat. No. 4,833,048 have proposed J. Elec.
trochem.Soc, Vol.137, No.4, p.1191 to 1192 (1990) and
J. Electrochem. Soc, Vol.138, No.7, 1896-1901 (1991)
As reported in (1), a disulfide monomer or a prepolymerized disulfide compound polymer is impregnated in carbon felt or is mixed with a conductive material such as carbon black. However, when a battery is formed by using a liquid or an electrolyte containing a liquid as the electrolyte by simply impregnating the conductive material with the disulfide compound or simply mixing, the retention of the disulfide compound in the electrode is insufficient and the battery is charged. There is a problem that the disulfide compound flows out from the electrode during repeated polymerization and depolymerization of the disulfide compound with discharge, and the battery capacity deteriorates.
Further, when a polymer solid electrolyte such as polyethylene oxide in which a lithium salt is dissolved is used, the conductive material and the disulfide compound are not uniformly dispersed, and when polymerization and depolymerization are repeated, the nonuniformity is further increased and the conductive material There is a problem in that a lump of a disulfide compound that is not electrically connected to and cannot be charged and discharged is generated in the electrode and the battery capacity is deteriorated.

The present invention solves such problems, and an object of the present invention is to provide a method for producing an electrode containing a disulfide compound as a main component, which causes little capacity deterioration during battery charge / discharge.

[0005]

In order to achieve the above object, in the method for producing a polymer electrode of the present invention, a sulfur-sulfur bond is cleaved by electrolytic reduction to form a sulfur-metal ion (including a proton) bond. In the method for producing a polymer electrode using an organic sulfur compound monomer whose sulfur-metal ion bond regenerates the original sulfur-sulfur bond by electrolytic oxidation as a raw material component, the organic sulfur compound monomer is dissolved in an organic solvent to obtain a product. After mixing the solution and the conductive substance, the monomer in the mixture is polymerized.

In the above structure, the conductive substance is preferably a conductive polymer powder. Further, in the above structure, the conductive substance is preferably polyaniline powder.

Further, in the above structure, the conductive substance is preferably a composite of a fluororesin and a carbon material.

[0008]

According to the above-mentioned constitution of the present invention, the organic sulfur compound monomer whose sulfur-metal ionic bond regenerates the original sulfur-sulfur bond by electrolytic oxidation is dissolved in an organic solvent, and the solution and conductivity By mixing the substance with the substance and then polymerizing the monomer in the mixture, it is possible to produce an electrode containing a disulfide compound as a main component, which causes less capacity deterioration during battery charge and discharge. That is, the disulfide compound monomer is uniformly mixed with the conductive substance in a state of being dissolved in the solution, and then polymerized, so that an electrode in a state where the polymer of the disulfide compound and the conductive substance are uniformly mixed and dispersed is obtained. be able to. When a battery using such an electrode is charged and discharged, the electrical connection between the conductive substance and the disulfide compound is maintained well, and the deterioration of the battery capacity is reduced.

[0009]

EXAMPLES The present invention will be described in more detail with reference to the following examples. In the manufacturing method of the present invention, the electrode is manufactured by mixing the solution in which the disulfide compound monomer is dissolved with the conductive substance, and then polymerizing the disulfide compound monomer in the mixture. The disulfide compound monomer used in the present invention includes dithioglycol (ethanedithiol), 2,5-dimercapto-1,3,4-
Thiadiazole, thiocyanuric acid (s-triazine-
2,4,6-trithiol), thiourea and the like are used. Solvents for dissolving these disulfide compound monomers include alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone,
Ethers such as ethyl ether, alkaline water, or a mixture thereof is used. Before dissolving the disulfide compound monomer, it is desirable to neutralize the disulfide compound monomer with lithium hydroxide in advance or at the same time. As the conductive material, acetylene black, carbon materials such as artificial graphite and natural graphite, polyaniline,
Conductive polymer materials such as polypyrrole and polythiophene are used. As the conductive substance, a composite of the above conductive substances with each other, or the above conductive substance and a polyolefin such as polypropylene or polybutene, a fluororesin such as polytetrafluoroethylene, or a synthetic rubber or the like is synthesized. A composite material with a resin material can also be used. In particular, a conductive polymer material having flexibility, and among them, polyaniline having a fibril structure or a porous structure and capable of effectively dispersing and holding a disulfide compound is preferable. Furthermore, the conductive material that is a composite of acetylene black and polytetrafluoroethylene has conductivity and flexibility, and when the electrode material that is composited with a disulfide compound is molded for use in the electrode of an actual battery, It is particularly preferable because it gives the molded article good shape retention. The disulfide compound monomer can be polymerized by a chemical polymerization method using an oxidizing agent such as iodine, potassium ferricyanide, hydrogen peroxide or the like, or by an electrolytic oxidation method.

Specific embodiments will be described below. Example 1 5 gr of 2,5-dimercapto-1,3,4-thiadiazole (hereinafter referred to as DMcT) was used as a dibasic acid D.
100 ml of acetone-water (1: 1 volume) mixed solvent in which an equivalent amount of lithium hydroxide necessary for neutralizing McT was dissolved
In addition, it was neutralized and dissolved. In the obtained solution, polyaniline powder (electrical resistance = 1.6 s / cm, 25 ° C., average particle size =
6 μm) 7.5 gr were added, and the rotation speed was 1 with a homogenizer.
A dispersion was prepared by uniformly dispersing at 000 rpm. next,
DMcT was added to 100 ml of the same acetone-water mixed solvent.
An oxidant solution was prepared by dissolving an equivalent amount of iodine necessary to oxidize the above compound and the same molar number of lithium iodide as iodine. Rotation speed of the dispersion liquid prepared above is 1000 rpm with a homogenizer.
The oxidant solution was added dropwise over 2 hours while stirring with D.
The McT monomer was polymerized. After the dropping, the mixture was allowed to stand for a whole day and night, the supernatant was discarded, the precipitate was washed with 200 ml of acetone, the precipitate was washed with 200 ml of pure water three times, and finally with acetone again, and then filtered.
Vacuum dry (1 mmHg) at 60 ° C for 17 hours and DMcT
Electrode powder A in which polymer and polyaniline powder are composited
Got

Comparative Example 1 DMcT (5 gr) was neutralized and dissolved by adding 100 ml of an acetone-water (1: 1 volume) mixed solvent in which an equivalent amount of lithium hydroxide necessary for neutralizing the dibasic acid DMcT was dissolved. The same oxidizing agent solution as in Example 1 was added dropwise to the obtained solution to polymerize the DMcT monomer. After standing overnight, the precipitate was washed with acetone, pure water, and acetone in this order, and then vacuum dried to obtain 4.92 gr of a pale yellow powder of a DMcT monomer polymer. For 1 part by weight of this powder,
Electrode powder B was obtained by mixing 1.5 parts by weight of the same polyaniline powder as used in Example 1 in an alumina mortar.

Example 2 5 gr of transparent liquid dithioglycol (referred to as DTG)
Was added to 100 ml of an ethanol-water (1: 1 volume ratio) mixed solvent in which an equivalent amount of lithium hydroxide necessary for neutralizing the dibasic acid DTG was dissolved to neutralize and dissolve. To the obtained aqueous solution, 7.5 gr of the same polyaniline powder as used in Example 1 was added, and the number of revolutions was 100 with a homogenizer.
A dispersion was prepared by uniformly dispersing at 0 rpm. Next, an oxidant solution was prepared by dissolving an equivalent amount of iodine necessary for oxidizing DTG and lithium iodide in the same mole number as iodine in 100 ml of the same ethanol-water mixed solvent. The oxidant solution was added dropwise over 2 hours while stirring the dispersion liquid prepared above with a homogenizer at a rotation speed of 1000 rpm.
The monomer was polymerized. After the dropping, the mixture was allowed to stand for a whole day and night, the supernatant was discarded, the precipitate was washed with 200 ml of acetone, the precipitate was washed with 200 ml of pure water three times, and finally with acetone again, and then filtered. ℃
After vacuum drying (1 mmHg) for 17 hours, an electrode powder C in which the DTG polymer and the polyaniline powder were composited was obtained.

Comparative Example 2 DTG (5 gr) was neutralized and dissolved by adding 100 ml of an acetone-water (1: 1 volume ratio) mixed solvent in which an equivalent amount of lithium hydroxide necessary for neutralizing the dibasic acid DTG was dissolved. . The same oxidizing agent solution as in Example 1 was added dropwise to the obtained solution to polymerize the DTG monomer. After standing overnight, the precipitate was washed with acetone, pure water, and acetone in this order, and then vacuum dried to obtain 4.98 gr of a white powder of a polymer of DTG monomer. Electrode powder D was obtained by mixing 1 part by weight of this powder with 1.5 parts by weight of the same polyaniline powder as used in Example 2 in an alumina mortar.

Evaluation of Battery Performance Electrode powders A and C obtained in Examples 1 and 2 and Comparative Example 1
Using the electrode powders B and D obtained in 2 as the positive electrode active material,
Using a metal lithium having a thickness of 0.3 mm as a negative electrode, 3.0 g of polyacrylonitrile was gelled with 20.7 g of a propylene carbonate / ethylene carbonate (1: 1 volume ratio) solution in which 1 M of LiBF ⁴ was dissolved to a thickness of 0.6 mm. , A battery having a diameter of 13 mm is formed, and a constant current value of 0.27 mA is applied to the battery.
A charge / discharge test was performed within a range of 2.50 V to evaluate the battery characteristics of each electrode powder. 1, 5, 10, 20, 3
It was evaluated by the discharge capacity after 0 cycle. The positive electrode was prepared by mixing 2.5 parts by weight of each electrode powder and 2.5 parts by weight of a gel electrolyte and molding the mixture into a sheet having a thickness of 0.17 mm.
A disc punched out with a diameter of 13 mm was used. The weight of all the electrodes was 20 mg. The test results are shown in Table 1.

[0015]

[Table 1]

As is clear from the above results, in the batteries using the electrode powders A and C of Examples 1 and 2 produced by the method according to the present invention, 77% of the capacity at the first cycle was obtained even after 30 cycles of charging and discharging. , 74%, while the batteries using the electrode powders B and D of Comparative Examples 1 and 2 manufactured by the conventional method only hold the discharge capacities of 40% and 38%.

As described above, according to this example, the solution in which the disulfide compound monomer is dissolved and the conductive substance are uniformly mixed, and then the resulting dispersion solution is added with an oxidizing agent such as iodine or potassium ferricyanide. The precipitate obtained by polymerizing the disulfide compound monomer by adding is washed, filtered and dried to produce a polymer electrode composed of a composite of a polymer of the disulfide compound and a conductive substance. The disulfide compound monomer may be oxidatively polymerized by electrolyzing the dispersion solution. As a result, it is possible to obtain an electrode with little capacity deterioration during battery charging and discharging.

[0018]

According to the production method of the present invention, the disulfide compound monomer is homogeneously mixed with the conductive substance in a state of being dissolved in a solution, and then polymerized, so that the disulfide compound polymer and the conductive substance are mixed. It is possible to obtain an electrode in a state of being uniformly mixed and dispersed. Then, when a battery using such an electrode is charged / discharged, the electrical connection between the conductive substance and the disulfide compound is maintained well, and the deterioration of the battery capacity is reduced.

Claims (4)

[Claims] 1. A sulfur-sulfur bond is cleaved by electrolytic reduction to form a sulfur-metal ion (including proton) bond, and a sulfur-metal ion bond is converted to the original sulfur-
In a method for producing a polymer electrode using an organic sulfur compound monomer that regenerates a sulfur bond as a raw material component, the organic sulfur compound monomer is dissolved in an organic solvent, and the obtained solution is mixed with a conductive substance, and then in a mixture. A method for producing a polymer electrode, which comprises polymerizing the above monomer. 2. The method for producing a polymer electrode according to claim 1, wherein the conductive substance is a conductive polymer powder. 3. The method for producing a polymer electrode according to claim 1, wherein the conductive substance is polyaniline powder. 4. The method for producing a polymer electrode according to claim 1, wherein the conductive substance is a composite of a fluororesin and a carbon material.