JPH08213021A - Composite electrode containing organic disulfide compound, manufacture thereof, and lithium secondary battery - Google Patents

Abstract

PURPOSE: To provide a composite electrode in which drop in electrode capacity is small even after charging discharging cycles are repeated by integrally supporting a composition containing a specific organic disulfide compound and polyaniline in a copper foil. CONSTITUTION: A composition (example: N-methyl-2-pyrrolidone solution) containing an organic disulfide compound (example: 2,5-dimercapto-1,3,4- thiadiazyl) which generates a S-metal ion (containing a proton) bond by cleavage of S-S bond by electrolytic reduction and regenerates the original S-S bond from the S-metal ion bond by electrolytic oxidation and polyaniline, preferably containing 0.01-10 pts.wt. polyaniline based on 1 pts.wt. organic disulfide compound is applied, for example, to a copper foil, dried, and vacuum-heated for integrally supporting. Or, a composition containing the organic disulfide compound, polyaniline, and metallic copper is integrally supported in a conductive substrate (example: titanium foil).

Description

Detailed Description of the Invention

[0001]

The present invention relates to a composite electrode containing an organic disulfide compound used in electrochemical devices such as batteries, electrochromic display devices, sensors and memories.
The manufacturing method and a lithium secondary battery using a composite electrode as a positive electrode.

[0002]

2. Description of the Related Art Since conductive polyacetylene was discovered in 1971, when conductive polymers were used as electrode materials,
Electroconductive polymer electrodes have been actively studied because they can be expected to be lightweight and high energy density batteries, large-area electrochromic devices, and electrochemical devices such as biochemical sensors using microelectrodes. Since polyacetylene is unstable and poor in practicality as an electrode, other π-electron conjugated conductive polymers have been studied, and relatively stable polymers such as polyaniline, polypyrrole, polyacene, and polythiophene have been developed. A lithium secondary battery used for the positive electrode is being developed. The energy density of these batteries is said to be 40-80 Wh / kg. Recently, an organic disulfide compound has been proposed in US Pat. No. 4,833,048 as an organic material which can be expected to have a higher energy density. This compound is the easiest
M ⁺ - ^over S-R-S ^{chromatography} -M ⁺ and represented by (R is an aliphatic or aromatic organic group, S is sulfur, M ⁺ is a proton or a metal cation). This compound is S-S by electrolytic oxidation.
Through binding bind to each other, M ⁺ - to polymerize at ^over S-R-S-S- R-S-S-R-S ^{chromatography} -M ⁺ form such as. The polymer thus produced returns to the original monomer by electrolytic reduction. A metal-sulfur secondary battery in which a metal M for supplying and capturing a cation (M ⁺ ) and an organic disulfide compound is combined is proposed in the above-mentioned US patent. This battery is 150 Wh / kg
From the above, an energy density comparable to or higher than that of an ordinary secondary battery can be expected.

[0003]

However, such an organic disulfide compound has a problem that the electrode capacity gradually decreases when oxidation-reduction (charge / discharge) is repeated. When an organic disulfide compound is oxidized (charged), a polydisulfide compound having electrical insulation and poor ion conductivity is produced. Polydisulfide compounds have poor solubility in electrolytes. On the other hand, the organic disulfide monomer produced when this polydisulfide compound is converted into a monomer by reduction (discharge) has high solubility in an electrolyte. Therefore, when oxidation-reduction is repeated, the monomerized disulfide is partially dissolved in the electrolyte, and the dissolved monomer is polymerized at a place different from the place originally located in the electrode. Then, the polydisulfide compound which is polymerized and deposited away from the conductive agent such as carbon is isolated from the electron / ion conduction network in the electrode and is not involved in the electrode reaction. When the redox is repeated, the amount of isolated polydisulfide compound increases and the capacity of the battery gradually decreases. In addition, the highly soluble organic disulfide monomer is easy to move and dissipates from the positive electrode into the separator or the electrolyte, and further to the negative electrode side. Therefore, a battery using an electrode containing an organic disulfide compound as a positive electrode has drawbacks of low charge / discharge efficiency and short charge / discharge cycle life.

The present invention solves such problems and provides a composite electrode which does not impair the high energy density of the organic disulfide compound, maintains high charge / discharge efficiency, and obtains good charge / discharge cycle characteristics. The purpose is to do. Another object of the present invention is to provide a lithium secondary battery using the composite electrode.

[0005]

In the composite electrode of the present invention, the sulfur-sulfur bond is cleaved by electrolytic reduction to generate a sulfur-metal ion (including proton) bond, and the electrolytic oxidation causes the sulfur-metal ion bond to be changed. This is a composition in which an organic disulfide compound that regenerates the original sulfur-sulfur bond and a composition containing polyaniline are supported and integrated on a metallic copper foil. Further, the composite electrode of the present invention is one in which a composition containing an organic disulfide compound, polyaniline and metallic copper is supported and integrated on a conductive substrate.

The method for producing a composite electrode of the present invention is obtained by the first step of dissolving an organic disulfide compound in N-alkyl-2-pyrrolidone, the second step of adding and dissolving polyaniline powder to the obtained solution, and the second step. The third step of applying the obtained solution on a metal copper foil and heating in a vacuum or in an inert gas atmosphere is included. Further, in the method for producing a composite electrode of the present invention, the first step of dissolving the organic disulfide compound in N-alkyl-2-pyrrolidone, the second step of adding and mixing the metal copper powder to the obtained solution, and the metal copper powder are mixed. There is a third step of adding and mixing the polyaniline powder to the solution, and a fourth step of applying the solution in which the polyaniline powder is added and mixed on a conductive substrate and heating in a vacuum or in an inert gas atmosphere. The lithium secondary battery of the present invention comprises a positive electrode, a non-aqueous electrolyte, and a negative electrode which are composed of a composite electrode containing the above organic disulfide compound. Here, the N-alkyl-2-pyrrolidone has the formula R
-NC ₄ H ₆ O (R represents a hydrogen atom or an alkyl group such as a methyl group, an ethyl group, and an n-butyl group).

[0007]

[Function] Copper, which is one of the components of the composite electrode, forms a complex with the polyaniline and the organic disulfide compound by the charge / discharge reaction, and the organic disulfide compound and the complex with the polyaniline are dissolved in the electrolyte, It has the function of preventing dissipation. Therefore, an excellent charge / discharge cycle life can be obtained. Further, the composite electrode of the present invention gives a flatter voltage as compared with the composite electrode containing only polyaniline and an organic disulfide compound. The present inventor considers such an action as follows. When the composite electrode is used as a positive electrode and metallic lithium as a negative electrode, and the positive electrode is charged with a constant current in an electrolyte made of an aprotic organic solvent in which a lithium salt is dissolved, the positive electrode is dissolved at around 3.2 to 3.4 V with respect to metallic lithium. Copper metal having a deposition voltage dissolves as copper cations. With this dissolution reaction,
The N—S bond between the S atom of the organic disulfide compound and the N atom of polyaniline causes oxidation of the organic disulfide compound forming the complex, and the organic disulfide compound is polymerized to form polydisulfide. Next, when this battery is discharged, the polydisulfide forming a complex by N—S bond at the N-position of polyaniline becomes a disulfide monomer anion, and this anion and a copper cation produced by charging and a counter ion or a copper ion. Forming a complex,
Prevents the disulfide monomer from diffusing into the electrolyte and dissipating from the positive electrode. Furthermore, S atoms other than the S atom of the organic disulfide compound bonded to the N atom of polyaniline form a counterion or a copper complex with the copper cation, and the polyaniline, the organic disulfide compound and copper are molecularly connected to each other in the positive electrode. To form a higher-order structure and prevent the complex from dissolving and diffusing into the electrolyte. The formation of this counterion or copper complex also prevents the diffusion of the copper cation itself into the electrolyte,
It prevents the copper cation, which causes self-discharge, from reaching the negative electrode and reacting with metallic lithium. Further, since the counter ion or the copper complex serves as a reaction species of the battery reaction, it gives a flatter voltage as compared with the composite electrode containing only polyaniline and the organic disulfide compound.

Further, according to the method for producing a composite electrode of the present invention, the addition of polyaniline for increasing the viscosity of the solution is carried out after the organic disulfide compound is dissolved or after the metal copper powder is further added. A solution in which polyaniline is uniformly and highly dissolved in N-alkyl-2-pyrrolidone, or a solution in which an organic disulfide compound and polyaniline are uniformly and highly dissolved in N-alkyl-2-pyrrolidone and metal copper powder is uniformly dispersed Obtainable. Since the solution prepared in this way is applied to the metal copper foil or the conductive substrate, a high density and uniform pinhole-free composite electrode film can be obtained. Furthermore, since the complex of the disulfide compound and polyaniline and the metal copper foil or the metal copper powder are chemically and strongly bonded to each other via the counter ion or the copper complex, stable charge / discharge characteristics can be obtained.

[0009]

Examples As the disulfide compound used in the present invention, the general formula (R shown in US Pat. No. 4,833,048) can be used.
A compound represented by (S) _y ) _n (wherein R is an aliphatic group or an aromatic group, S is sulfur, y is an integer of 1 or more, and n is an integer of 2 or more) can be used. . HSCH ₂ CH ₂
Dithioglycol represented by SH, C ₂ N ₂ S (SH) ₂
2,5-dimercapto-1,3,4-thiadiazyl represented by, s-triazine-2,4,6-trithiol represented by C ₃ H ₃ N ₃ S ₃ , and 7 represented by C ₆ H ₆ N ₄ S _3.
-Methyl-2,6,8 over tri-mercaptopurine, or C ₄ H ₆ N ₄ S 4,5- diamino 2,6 over dimercaptopyrimidine like represented by ₂ is used. In each case, a commercially available product can be used as it is. Further, these organic disulfide compounds are chemically polymerized using an oxidizing agent such as iodine, potassium ferricyanide, or hydrogen peroxide,
Alternatively, a polymer containing a dimer or tetramer of an organic disulfide compound polymerized by the electrolytic oxidation method can be used.

As the polyaniline used in the present invention, those obtained by polymerizing aniline or a derivative thereof by a chemical polymerization method or an electrolytic polymerization method are used. In particular,
Dedoped polyaniline is preferable because it effectively traps the organic disulfide monomer. The degree of reduction (RDI) of polyaniline is the electron absorption spectrum of a solution of polyaniline dissolved in N-methyl-2-pyrrolidone in a trace amount, and the intensity (I ₃₄₀ ) of the absorption peak due to the para-substituted benzene structure appearing on the short wavelength side around 340 nm. , 6
By the ratio with the intensity (I ₆₄₀ ) of the absorption peak due to the quinonediimine structure appearing on the long wavelength side near 40 nm, R
It is represented by DI = I ₆₄₀ / I ₃₄₀ . Polyaniline having an RDI of 0.5 or less is preferably used. The degree of dedoping of polyaniline is represented by conductivity. Conductivity is ^10-5
Polyaniline of S / cm or less is preferably used.

As the N-alkyl-2-pyrrolidone used in the production method of the present invention, commercially available reagents can be used as they are, or those whose water content is reduced to 20 ppm or less by a zeolite adsorbent can be used. Pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone,
N-butyl-2-pyrrolidone or the like can be used.
The metallic copper foil or metallic copper used in the present invention may be pure copper or a copper alloy containing a metal other than copper. In the case of foil, the thickness is preferably 0.1 μm to 100 μm.
In the case of powdery or fibrous metallic copper or copper alloy, those having a particle diameter, a fiber diameter and a fiber length of 100 angstrom to 10 μm are preferable. Further, a clad material in which a copper foil is laminated with a metal foil such as titanium, aluminum or stainless steel, or a metal foil such as copper-plated titanium, aluminum or stainless steel may be used. Copper foil and clad material are
It is also possible to use a flat or uneven surface having a plurality of regular or irregular through holes. Further, a material in which the surface of particles of synthetic resin such as acrylic resin is coated with copper or copper alloy may be used. The ratio of the organic disulfide compound and the polyaniline is 0.06 parts by weight of polyaniline to 1 part by weight of the organic disulfide compound.
1 to 10 parts by weight is preferable. The proportion of metallic copper is preferably 0.01 to 10 parts by weight based on 1 part by weight of the total amount of the organic disulfide compound and polyaniline.

The conductive substrate used in the manufacturing method of the present invention includes a porous carbon film made of carbon black and fluororesin, a metal foil such as titanium, aluminum or stainless steel, a conductive polymer film such as polyaniline or polypyrrole. A film, or a metal foil or carbon film coated or covered with a conductive polymer film can be used. As the metal cation M + when the organic disulfide is reduced to form a salt, a copper cation can be used in addition to the alkali metal cation and the alkaline earth metal cation described in the above-mentioned US Patent. A conductive agent may be added to the composite electrode of the present invention for the purpose of further increasing the conductivity. Such conductive agents include graphite powder, graphite fibers, carbon powder or fibers such as acetylene black powder, and conductive polymers such as polypyrrole and polythiophene other than polyaniline. In particular, the polypyrrole represented by the following formula (1), which is soluble in N-alkyl-2-pyrrolidone and is used in the production method of the present invention, is preferable because it can enhance the film-forming property of the composite electrode and obtain good conductivity.

[0013]

Embedded image

(In the formula, R is an alkyl group, and n is a number indicating the degree of polymerization. For example, R = C ₄ H ₉ and C ₂ H ₅ and C ₄ H ₉ : C
₂ H ₅ = 1: 2, is n = 200 to 1,000. )

The composite electrode of the present invention comprises a metal cation M ⁺
You may add the electrolyte containing. As such an electrolyte, a solid or semi-solid polymer electrolyte in which the organic disulfide monomer is less likely to diffuse and move is preferable. LiClO ₄ , LiCF _{3 on} polyethylene oxide
LiClO ₄ , Li in a polymer solid electrolyte in which a lithium salt such as SO ₃ or LiN (CF ₃ SO ₂ ) ₂ is dissolved, or in a non-aqueous solvent such as propylene carbonate or ethylene carbonate.
CF ₃ SO ₃ , LiBF ₄ , LiPF ₆ , LiN (CF ₃ S
A semi-solid polymer electrolyte obtained by gelling an electrolytic solution in which a lithium salt such as O ₂ ) ₂ is dissolved with a polymer such as polyacrylonitrile, polyvinylidene fluoride, or polyacrylic acid is effectively used. A liquid electrolyte in which the lithium salt of N-alkyl-2-pyrrolidone is dissolved in about 1 M may be added. Furthermore, an organic polymer binder such as polyvinylpyrrolidone, polyvinyl alcohol, or polyvinyl pyridine may be added to the composite electrode of the present invention for the purpose of enhancing film forming properties and obtaining high film strength.

[Example 1] 2,5-dimercapto-1,
N-methyl-2-pyrrolidone (hereinafter NMP) was added to 2.0 g of 3,4-thiadiazyl (hereinafter referred to as DMcT) powder.
It was dissolved in 7.0 g. Then, Nitto Denko polyaniline (trade name Anirido) dedoped in an alkaline solution, the conductivity obtained by reduction with hydrazine is 10 ^{@ 8} S
/ Cm, 1.0g of dedoped reduced polyaniline powder having an RDI value of 0.26 was added to the above solution and dissolved to obtain a blue-green viscous DMcT-polyaniline (hereinafter referred to as PAn) -NMP solution. . This solution should have a gap of 15
After coating on a metal copper foil having a thickness of 10 μm with an applicator having a thickness of 0 μm, it is heated in an argon gas stream at 80 ° C. for 15 minutes, and further vacuum heated at 80 ° C. for 60 minutes to form a composite electrode having a thickness of 35 μm Got The obtained composite electrode was cut into a 2 × 2 cm square. This is referred to as composite electrode A.

[Comparative Example 1] Instead of the metal copper foil, a thickness of 10 was obtained.
A composite electrode A ′ having a thickness of 35 μm was obtained in the same manner as in Example 1 except that a titanium foil having a thickness of μm was used.

Example 2 2.0 g of DMcT powder was added to NM
It was dissolved in 7.0 g of P. Then, Nitto Denko polyaniline (trade name Anirido) the conductivity obtained is reduced with dedoped with hydrazine in an alkaline solution is 10 ^{@ 8} S / cm,
1.0 g of dedoped reduced polyaniline powder having an RDI value of 0.30 was added to and dissolved in the above solution, and 9.7 g of NMP was further added to obtain a blue-green DMcT-PAn-NMP solution. Further, a solution prepared by dissolving 0.5 g of the soluble polypyrrole represented by the above formula (1) in 5.0 g of NMP was added to obtain a viscous DMcT-PAn-PPy-NMP solution. 1.0% of acetylene black powder was added to this solution.
g was added and uniformly mixed to obtain a black ink. This black ink was applied onto a metal copper foil having a thickness of 30 μm with an applicator having a gap of 250 μm, and then heated at 80 ° C. for 15 minutes in an argon gas stream, and further,
It was vacuum-heated at 80 ° C. for 60 minutes to obtain a composite electrode having a thickness of 55 μ. The obtained composite electrode was cut into a 2 × 2 cm square. This is referred to as composite electrode B.

[Comparative Example 2] Instead of the metallic copper foil, a thickness of 30
A composite electrode B ′ having a thickness of 55 μm was obtained in the same manner as in Example 2 except that a titanium foil having a thickness of μm was used.

[Example 3] 2.0 g of DMcT powder was added to NM
It was dissolved in 7.0 g of P. Then, Nitto Denko polyaniline (trade name Anirido) the conductivity obtained is reduced with dedoped with hydrazine in an alkaline solution is 10 ^{@ 8} S / cm,
1.0 g of dedoped reduced polyaniline powder having an RDI value of 0.25 was dissolved in the above solution, and NMP was added to 9.7.
g to obtain a blue-green DMcT-PAn-NMP solution. Further, a solution of 0.5 g of polyvinylpyrrolidone having an average molecular weight of 25,000 dissolved in 5.0 g of NMP was added to obtain a viscous DMcT-PAn-PVP-NMP solution. 1.0% of acetylene black powder was added to this solution.
g was added and uniformly mixed to obtain a black ink. This black ink was applied onto a metal copper foil having a thickness of 30 μm with an applicator having a gap of 250 μm, and then heated at 80 ° C. for 15 minutes in an argon gas stream, and further,
It was vacuum-heated at 80 ° C. for 60 minutes to obtain a composite electrode having a thickness of 55 μm. The obtained composite electrode was cut into a 2 × 2 cm square.
This is referred to as a composite electrode C.

[Comparative Example 3] Instead of the metallic copper foil, a thickness of 30
A composite electrode C ′ having a thickness of 55 μm was obtained in the same manner as in Example 3 except that the titanium foil of μ was used.

[Example 4] s-triazine-2,4,6
-1.5 g of trithiol (hereinafter referred to as TTA) powder was dissolved in 7.0 g of NMP. Then, Nitto Denko polyaniline (trade name Anirido) the conductivity obtained is reduced with dedoped with hydrazine in an alkaline solution is 10 ^{@ 8} S / c
m, 1.0 g of dedoped reduced polyaniline powder having an RDI value of 0.18 was dissolved in the above solution, and NMP was added to 9.
7 g was added to obtain a blue-green TTA-PAn-NMP solution. Furthermore, 0.5 of the soluble polypyrrole represented by the formula (1) is used.
The solution which melt | dissolved g in 5.0 g of NMP was added, and the viscous TTA-PAn-PPy-NMP solution was obtained. 1.0 g of acetylene black powder was added to this solution and uniformly mixed to obtain a black ink. This black ink is applied with an applicator with a gap of 250 μm to a thickness of 30 μm.
After being coated on the metal copper foil of No. 1, heated at 80 ° C. for 15 minutes in an argon gas stream, and further vacuum-heated at 80 ° C. for 60 minutes, a composite electrode having a thickness of 58 μ was obtained. The obtained composite electrode was cut into a 2 × 2 cm square to obtain a composite electrode D.

[Comparative Example 4] Instead of the metal copper foil, a thickness of 30 was used.
A composite electrode D ′ having a thickness of 58 μm was obtained in the same manner as in Example 3 except that μ titanium foil was used.

[Example 5] 2.0 g of DMcT was added to NMP
It was dissolved in 7.0 g. 0.5 g of metallic copper powder having an average particle size of 1 μm was added to this solution to obtain a slightly reddish ink. Then, Nitto Denko polyaniline (trade name Anirido) the conductivity obtained is reduced with dedoped with hydrazine in an alkaline solution is 10 ^{@ 8} S / cm, RDI value 0.
1.0 g of 28 dedoped reduced polyaniline powder was added and dissolved. This ink was applied onto a titanium foil having a thickness of 10 μm using an applicator with a gap of 150 μm,
After heating at 80 ° C. for 15 minutes in an argon gas stream, heat treatment was performed at 80 ° C. for 60 minutes under a reduced pressure of 1 cmHg to obtain a composite electrode having a thickness of 35 μm. The obtained electrode was cut into a 2 × 2 cm square to obtain a composite electrode E.

[Comparative Example 5] A composite electrode E'having a thickness of 35 µm was obtained in the same manner as in Example 5 except that an ink containing no metallic copper powder was used in the DMcT-PAn-NMP solution.

Example 6 2.0 g of DMcT powder was added to NM
It was dissolved in 7.0 g of P. Furthermore, 9.7 g of NMP was added to obtain a blue-green DMcT-NMP solution. To this solution, 0.5 g of acetylene black powder and metallic copper powder having an average particle size of 1 μm were added and uniformly mixed. Then, Nitto Denko polyaniline (trade name Anirido) the conductivity obtained is reduced with dedoped with hydrazine in an alkaline solution is 10 ^{@ 8} S / cm, de-doped reduced polyaniline powder 1 of RDI value of 0.25 Dissolve 0.0 g, and 0.5 g of polyvinylpyrrolidone having an average molecular weight of 25,000.
Was added to 2.5 g of NMP to obtain a black ink. This black ink was applied on a titanium foil having a thickness of 30 μm with an applicator having a gap of 250 μm, and then heated at 80 ° C. for 15 minutes in an argon gas stream, and further heated at 80 ° C. for 60 minutes under vacuum. , Thickness 5
A composite electrode of 0 μm was obtained. 2 x 2c of the obtained composite electrode
A composite electrode F was obtained by cutting into m squares.

[Comparative Example 6] DMcT-PAn-PVP-
A composite electrode F ′ having a thickness of 50 μm was obtained in the same manner as in Example 6 except that an ink containing no metallic copper powder was used in the NMP solution.
I got

Evaluation of Electrode Performance Examples 1, 2, 3, 4, 5, 6, Comparative Examples 1, 2, 3,
Electrodes A, B, C, D, E, F, A ′ obtained in 4, 5, 6
B ', C', D ', E', F'is the positive electrode, thickness 0.3 mm
Of the lithium metal as a negative electrode and a gel electrolyte having a thickness of 0.6 mm as a separator layer, the flat batteries A, B, C, D, E,
F, A ', B', C ', D', E ', F'was constructed.
The gel electrolyte is a gel of 20.7 g of a propylene carbonate / ethylene carbonate (1: 1 volume ratio) solution in which 1 M LiBF ₄ was dissolved and which was gelled with 3.0 g of polyacrylonitrile. These batteries were repeatedly charged and discharged at a constant current of 0.2 mA at 20 ° C. in the range of 4.65 to 2.0 V, and the discharge capacity (Q, unit: mAh) in each charge / discharge cycle was measured. The discharge cycle characteristics were evaluated. The results are shown in Table 1. In addition, the battery A,
Charge / discharge No. 5 for A ', batteries B, B', batteries E, E '
The discharge voltage at the cycle is shown in FIGS. 1, 2 and 3, respectively.

[0029]

[Table 1]

As is clear from the above results, the composite electrodes A, B of Examples 1, 2, 3, 4, 5, 6 according to the present invention,
The batteries using C, D, E, and F have lower discharge capacities during charge / discharge cycles than the batteries using the corresponding composite electrodes A'B'C'D'E'F 'of comparative examples. small. Further, the discharge voltage of the battery using the composite electrode of the example is 3.5 to 10 times that of the battery using the composite electrode of the comparative example.
It provides a relatively flat voltage between 2.5V.

[0031]

As described above, according to the present invention, it is possible to obtain a composite electrode having a small capacity reduction even if oxidation-reduction is repeated. When this composite electrode is used for the positive electrode, it is possible to obtain a high energy density secondary battery in which the dissipation of the positive electrode active material from the positive electrode during charging / discharging is reduced and the decrease in discharge capacity during charging / discharging is small. Moreover, a flat discharge voltage can be obtained. Although only the battery using the electrode composition was shown in the examples, by using the composite electrode of the present invention as a counter electrode in addition to the battery, an electrochromic device having a fast coloring / fading speed, a glucose sensor having a fast response speed, etc. Can be obtained, and an electrochemical analog memory with high writing / reading speed can be constructed.

[Brief description of drawings]

FIG. 1 is a diagram showing a discharge voltage of a lithium secondary battery using a composite electrode A of Example 1 of the present invention and a composite electrode A ′ of Comparative Example 1 as positive electrodes.

FIG. 2 is a diagram showing a discharge voltage of a lithium secondary battery using a composite electrode B of Example 2 and a composite electrode B ′ of Comparative Example 2 as positive electrodes.

FIG. 3 is a diagram showing a discharge voltage of a lithium secondary battery using a composite electrode E of Example 5 and a composite electrode E ′ of Comparative Example 5 as positive electrodes.

Claims (5)

[Claims] 1. A sulfur-sulfur bond is cleaved by electrolytic reduction to form a sulfur-metal ion (including proton) bond,
A composite electrode containing an organic disulfide compound characterized in that a composition containing polyaniline and an organic disulfide compound whose sulfur-metal ionic bond regenerates the original sulfur-sulfur bond by electrolytic oxidation are integrated on a metal copper foil. . 2. The electrolytic reduction reduces the sulfur-sulfur bond to form a sulfur-metal ion (including proton) bond,
Contains an organic disulfide compound characterized in that a sulfur-metal ionic bond regenerates the original sulfur-sulfur bond by electrolytic oxidation and a composition containing polyaniline and metallic copper is supported and integrated on a conductive substrate. A composite electrode. 3. The sulfur-sulfur bond is cleaved by electrolytic reduction to form a sulfur-metal ion (including proton) bond,
The first step of dissolving an organic disulfide compound whose sulfur-metal ion bond regenerates the original sulfur-sulfur bond by electrolytic oxidation in N-alkyl-2-pyrrolidone, the second step of adding and dissolving polyaniline powder in the resulting solution, A method for producing a composite electrode containing an organic disulfide compound, which comprises a third step of applying the solution obtained in the two steps onto a metal copper foil and heating it in a vacuum or in an inert gas atmosphere. 4. The sulfur-sulfur bond is cleaved by electrolytic reduction to form a sulfur-metal ion (including proton) bond,
A first step of dissolving an organic disulfide compound whose sulfur-metal ionic bond regenerates the original sulfur-sulfur bond by electrolytic oxidation in N-alkyl-2-pyrrolidone, a second step of adding and mixing metallic copper powder to the resulting solution, Third step of adding and mixing the polyaniline powder to the solution in which the metal copper powder is mixed, coating the solution in which the polyaniline powder is added and mixed on a conductive substrate, and heating in a vacuum or in an inert gas atmosphere A method for producing a composite electrode containing an organic disulfide compound, which comprises steps. 5. A lithium secondary battery comprising a positive electrode comprising a composite electrode containing the organic disulfide compound according to claim 1 or 2, a non-aqueous electrolyte, and a negative electrode.