JP2715778B2 - Reversible electrode material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reversible electrode material, a method for producing a reversible electrode using the same, and a lithium battery using the reversible electrode.

[0002]

2. Description of the Related Art Since the discovery of conductive polyacetylene by Shirakawa et al. In 1971, the use of this conductive polymer as an electrode material has been actively studied. When a conductive polymer is used as an electrode material, it can be expected to manufacture a light-weight, high-energy-density battery, a large-area electrochromic device, and an electrochemical device such as a biochemical sensor using microelectrodes. . Since polyacetylene is unstable and impractical as an electrode, other π-electron conjugated conductive polymers have been studied, and polyaniline, polypyro-
Relatively stable polymers such as toluene, polyacene, and polythiophene have been developed, and lithium secondary batteries using these as a positive electrode have been developed. These polymer electrodes take in not only cations but also anions in the electrolyte during the electrode reaction, so that the electrolyte in the battery not only acts as a transfer medium for ions but also participates in the battery reaction.
Therefore, there is a problem that an amount of electrolyte corresponding to the battery capacity is required in the battery, and as a result, the energy density of the battery is reduced. The energy density of such a battery is about 20 to 50 Wh / kg, which is about one half of that of a normal secondary battery such as a nickel cadmium storage battery or a lead storage battery.

[0003] US Patent No. 4,833,048 discloses a disulfide compound as an electrode material which can be expected to have a high energy density. This compound is most simply represented as R-S-S-R (R is an aliphatic or aromatic organic group and S is sulfur). The SS bond is cleaved by electrolytic reduction, and the cation (M ⁺ ) in the electrolytic bath is combined with the ^RS—
-Form a salt represented by M ⁺ . This salt returns to the original RSSR by electrolytic oxidation. The above cation (M ⁺ )
A metal-sulfur secondary battery combining a metal M and a disulfide-based compound for supplying and trapping a metal is proposed in the aforementioned U.S. Patent. In this secondary battery, 150 Wh /
With an energy density of kg or more, an energy density comparable to or higher than that of a normal secondary battery can be expected. U.S. Pat.
No. 048, or J. Electrochem Soc., Vol. 136, p.
2570-2575 (1989) describes introducing a catalyst to a disulfide compound electrode. Although an organometallic compound is disclosed as an electrode catalyst, its effect is not specifically described.

[0004]

A disulfide compound has been proposed as an electrode material capable of achieving a high energy density as described above. The disulfide compound is disclosed in US Pat. No. 4,833,048. J. Electroche
As reported in m. Soc, Vol. 136, No. 9, p. 2570-2575 (1989), the potentials for oxidation and reduction are very far apart.
For example, in the electrolysis of [(C ₂ H ₅ ) ₂ NCSS-] ₂ , the oxidation potential and the reduction potential are separated by 1 volt or more. Therefore, the electron transfer process is extremely slow according to the electrode reaction theory. Therefore, it is difficult to extract a large current suitable for practical use near room temperature, for example, a current of 1 mA / cm ² or more, and a battery having an electrode using such a compound can be used at a high temperature of 100 to 200 ° C. There was a problem of being limited.

The reversible electrode material of the present invention, a method for producing a reversible electrode using the electrode material, and a lithium battery using the reversible electrode solve the above-mentioned conventional problems.

[0006]

The electrode material of the present invention is a combination of a compound having a disulfide group and a conductive polymer, or an electrode material having a conductive polymer having a disulfide group, wherein the electrode material comprises a disulfide group. The SS bond is cleaved by electrolytic reduction to generate a sulfur-metal ion bond or a sulfur-proton bond, and the sulfur-metal ion bond or the sulfur-proton bond forms an SS bond by electrolytic oxidation.

In a preferred embodiment, the electrode material comprises:
It has a combination of a compound having a disulfide group and a conductive polymer, and the compound having a disulfide group has a cleavable disulfide bond in the molecule.

[0008] In a preferred embodiment, the conductive polymer having a disulfide group is obtained by introducing a disulfide group into a π-electron conjugated conductive polymer.

In a preferred embodiment, the conductive polymer having a disulfide group is capable of forming a π-electron conjugated conductive polymer and is obtained by electrolytic polymerization of a monomer having a disulfide group.

The method for producing a reversible electrode according to the present invention comprises a step of dimerizing a compound having a thiol group to obtain a dimer having a disulfide group, and a method of forming a monomer capable of forming a π-electron conjugated conductive polymer. And electrolytically polymerizing on the electrode substrate in the presence of the dimer.

The lithium secondary battery of the present invention has a positive electrode, a solid electrolyte, and a negative electrode, and the positive electrode has a sulfur-lithium ion-bonded lithium thiol bond capable of forming an SS bond of a disulfide group by electrolytic oxidation. Electron conjugated conductive polymer having a rate and a π-electron conjugated conductive polymer as a main component, or a sulfur-lithium ion bond capable of forming an SS bond of a disulfide group by electrolytic oxidation The solid electrolyte is a salt containing lithium, or a composition containing a polymer containing the salt as a main component, and the negative electrode,
It is composed of a composition containing aluminum or an aluminum-containing alloy and carbon as main components.

In a preferred embodiment, the solid electrolyte is mixed with a composition constituting the positive electrode or a composition constituting the negative electrode.

In a preferred embodiment, the solid electrolyte is a polyether obtained by adding at least one selected from the group consisting of ethylene oxide and propylene oxide to a polyamine; a compound having an ion-exchange layered crystal; and LiX. Wherein X is an anion of a strong acid.

[0014]

As described above, by using the electrode material of the present invention, it is not necessary to handle chemically active metallic lithium or its alloy when assembling the battery, and thus it is possible to assemble the lithium secondary battery safely. . Further, in the lithium secondary battery assembled in this way, by storing the battery in a discharged state, there is substantially no metallic lithium in the battery, so that there is no ignition when the battery is destroyed. Further, by using the battery of the present invention, a larger current can be obtained as compared with a conventional battery using metallic lithium or an alloy thereof as a negative electrode.

[0015]

The electrode material of the present invention contains (1) a combination of a compound having a disulfide group and a conductive polymer, or (2) a conductive polymer having a disulfide group.

The compound having a disulfide group used in the first electrode material of the present invention includes a compound represented by the general formula (R (S) _y ) _n disclosed in the above-mentioned US Pat. No. 4,833,048.
There is a compound represented by When this compound is reduced, it can be a reduced form represented by R (S) _y H or R (S) _y M. Here, R is an aliphatic group or an aromatic group, S is sulfur, H is a proton, M is a metal atom, y is an integer of 1 or more,
And n is an integer of 2 or more. For example, as a reduced form of the above compound, 2,5-dimercapto-1, represented by C ₂ N ₂ S (SH) ₂
Examples include 3,4-thiadiazole and s-triazine-2,4,6-trithiol represented by C ₃ H ₃ N ₃ S ₃ .

Compounds having a disulfide group in the molecule and having a configuration in which the cleavage of the SS bond of the disulfide group can reversibly occur in the molecule are also preferably used. , 8-disulfide naphthalene and the like. The compound having a disulfide group and the compound having a group capable of forming a disulfide group (such as a mercapto group) are collectively referred to as a disulfide compound.

As the conductive polymer, a π-electron shared conductive polymer is used, and examples thereof include polymers obtained by polymerizing thiophene, pyrrole, aniline, furan, benzene, and the like. Specifically, polyaniline,
There are polypyrrol, polythiophene, polyacene and the like.
These π-electron sharing conductive polymers cause a highly reversible oxidation-reduction reaction at 0 to ± 1.0 volt with respect to the Ag / AgCl electrode. These polymers can have a porous fibril structure depending on polymerization conditions, can hold a disulfide compound in pores, and can effectively produce a reversible electrode. The conductive polymer doped with an anion such as iodine exhibits excellent properties as a conductive polymer.

In the first electrode material of the present invention, the above-mentioned disulfide compound and conductive polymer are used in combination. These combinations can be performed by a known method such as mixing, impregnation, eutectoid, and recoating. For example,
After forming a fibril layer of a conductive polymer on a stainless steel substrate by electrolytic polymerization, a composite electrode can be obtained by impregnating the fibril layer with a salt of the disulfide compound. Alternatively, the conductive polymer layer may be formed on the surface of the disulfide compound particles by dispersing the disulfide compound particles in a solvent in which the conductive polymer is dissolved and then removing the solvent. Further, a conductive polymer powder obtained by chemical polymerization or electrolytic polymerization and a disulfide compound powder can be mixed.

Alternatively, a compound such as 1,8-disulfide naphthalene having a disulfide group in the molecule and having a configuration in which the SS bond of the disulfide group can be reversibly generated in the molecule. By polymerizing a monomer capable of forming a π-electron sharing conductive polymer in the presence, the electrode material of the present invention can be obtained. For example, when aniline is electrolytically polymerized on an electrode substrate in the presence of 1,8-disulfide naphthalene, a composite film of polyaniline-1,8-disulfide naphthalene is formed. Alternatively, as a further alternative, a compound obtained by dimerizing a compound having a thiol group can be used instead of the compound having a configuration in which the cleavage of the SS bond can reversibly occur in the molecule. For example, a dimer of thiazoline is obtained,
By using instead of 8-disulfide naphthalene, a polyaniline-2-mercapto-2-thiazoline dimer composite film is formed. In any of the above cases, it is preferable to carry out the polymerization under such polymerization conditions that a film having a fibril structure is formed. In these methods, since a compound in which a thiol group is protected is used, the conductive polymer can be prepared without being hindered. In the obtained composite membrane, since the disulfide compound and the conductive polymer form a composite, for example, when this is used as a positive electrode of a reversible battery, the disulfide compound may leak into the electrolyte. Absent.

In the second electrode material of the present invention, a conductive polymer having a disulfide bond is used. Such a conductive polymer having a disulfide bond includes, for example, (1) introducing a disulfide group into a π-electron shared conductive polymer; or (2) forming a π-electron shared conductive polymer. And subjecting the monomer having a disulfide group to electrolytic polymerization. As the π-electron sharing conductive polymer in the first method, the conductive polymer used for the first electrode material or a derivative thereof can be used. For example, a thin film of a polyhalogenated pyrrole is formed on an electrode substrate by electrolytic polymerization of a halogenated pyrrole. At this time, as in the case of the first electrode material, it is preferable to carry out the polymerization under conditions for forming a thin film having a fibril structure. Next, the halogen group is converted to a mercapto group with thiourea or the like. Next, a compound having a mercapto group is reacted with the compound to form a disulfide group. As the compound having a mercapto group, a disulfide compound (reduced type having an SH group) used for the first electrode material, for example, 2,5-dimercapto-1,3,4-thiadiazole is preferably used. Used. The thus formed conductive polymer in the form of a thin film having a disulfide bond can be used as a reversible electrode. As the monomer capable of forming the π-electron sharing conductive polymer in the second method, a monomer (thiophene, pyrrole, etc.) capable of forming the conductive polymer used for the first electrode material may have a disulfide group. Introduced monomers may be utilized. By polymerizing this monomer, a conductive polymer having a disulfide bond can be obtained. For example, a thiophene having a mercapto group is reacted with a dimercapto compound (reduced and having an SH group) used for the first electrode material such as 2,5-dimercapto-1,3,4-thiadiazole. By doing so, a thiophene derivative having a disulfide group is obtained. This is electrolytically polymerized on an electrode substrate to form a conductive polymer film having a disulfide group. It is preferable to carry out the polymerization under conditions that form a film having a fibril structure. The conductive polymer film thus formed functions as a reversible electrode.

When electrolytic reduction is performed when metal ions or protons coexist on the electrode using the electrode material of the present invention, the SS bond of the disulfide group of the electrode material is cleaved, and the sulfur-metal ion bond or sulfur A proton bond is formed. When this is electrolytically oxidized again, the original SS
Return to join. Examples of the metal ion include an alkali metal ion and an alkaline earth metal ion. When the electrode made of the electrode material of the present invention is used as a positive electrode and lithium ions are used as alkali metal ions, an electrode composed of lithium metal or a lithium alloy such as lithium-aluminum is used as an electrode for supplying and capturing lithium ions. And an electrolyte that conducts lithium ions, a battery having a voltage of 3 to 4 volts can be obtained. When a proton and an electrode composed of a metal hydride such as LaNi ₅ are used as a negative electrode as an electrode for supplying and capturing the proton, and an electrolyte that conducts the proton is used, a battery having a voltage of 1 to 2 volts is obtained. Can be

In the combination of the electrode material of the present invention with the disulfide compound and the π-electron shared conductive polymer, the π-electron shared conductive polymer is formed by electrolytic oxidation of the disulfide compound.
It acts as an electrode catalyst during reduction. Even in the case of a π-electron shared conductive polymer having a disulfide group, the π-electron shared structure acts as an electrode catalyst during the electrolytic oxidation and reduction of the disulfide group. In the case of the conventional disulfide compound alone, the potential difference between the oxidation reaction and the reduction reaction is 1 volt or more, but in the case of a combination of a π-electron sharing conductive polymer and a disulfide compound, or a conductive polymer having a disulfide group. Is that the potential difference between the oxidation reaction and the reduction reaction is 0.1 volt or less. A disulfide compound combined with or incorporated in a π-electron conjugated conductive polymer can take out a large current even at room temperature because the electrode reaction is accelerated. When the electric material of the present invention is subjected to electrolytic oxidation, first, a π-electron conjugated conductive polymer (a conjugated polymer portion in a conductive polymer having a disulfide group) is oxidized, and an oxidized form of the polymer is obtained. Is a reduced disulfide compound (in a conductive polymer having a disulfide group, S
The H or S-metal ion bond portion is oxidized and returned to the original reduced form, and an oxidized form of a disulfide compound is formed (a disulfide group is formed). When performing electrolytic reduction,
The conductive polymer is first reduced, and the resulting reduced form reduces the disulfide compound (oxidized form) and returns to the oxidized form, and the disulfide compound becomes a reduced form. The introduction of an electrocatalyst into a disulfide compound electrode is described in the aforementioned US Pat.
No. 33048 or J. Electrochem Soc., Vol. 136,
p.2570-2575 (1989). However, only an organometallic compound is disclosed as an electrode catalyst, and the effect of the electrode catalyst is not specifically shown. As described above, since the π-electron conjugated conductive polymer or the conjugated polymer portion has a function of promoting electron transfer in the oxidation-reduction reaction, it acts as a catalyst in the oxidation-reduction reaction and reduces the activation energy of the reaction. Has the function of reducing. At the same time, it has the effect of increasing the effective reaction area between the electrode and the electrolyte.

In the lithium battery of the present invention, an electrode composed of the above-mentioned electrode material of the present invention is used as a positive electrode, an electrode composed of a composition containing aluminum or an aluminum-containing alloy and carbon as main components is used as a negative electrode, , A solid electrolyte composed of a salt containing lithium or a polymer containing the salt.

As the material of the positive electrode, a combination of a lithium salt of a reduced form of a compound having a disulfide group and a conductive polymer; or an SS bond of the disulfide group is cleaved to form a thiol group, which is converted to a thiol group A conductive polymer having a group having a structure is used. For example, as a lithium salt of a reduced form of a compound having a disulfide group, there is a compound represented by C ₂ N ₂ S (SLi) _{2 represented} by 2,5-
Dimercapto-1,3,4-lithium thiolate, (C
_And diethyl dithiocarbamate represented by ₂ H ₄ ) ₂ C (S) (SLi). The conductive polymer,
It has a group derived from these compounds. In such an electrode material, lithium ions are liberated by electrolytic oxidation to form an SS bond, and conversely, the original S
-Return to Li.

As the carbon material contained in the negative electrode,
There are natural graphite, artificial graphite, amorphous carbon, fibrous carbon, powdered carbon, petroleum pitch-based carbon, and coal-coke-based carbon.
These carbon materials have a diameter or fiber diameter of 0.01 to 1
Particles or fibers having a diameter of 0 micron and a fiber length of several μm to several mm are preferred.

The aluminum or alloy thereof contained in the negative electrode includes Al, Al-Fe, Al-Si, Al-Zn, Al-Li, Al-Zn-S
i and others. The metallic aluminum or its alloy is preferably in the form of flakes obtained by ultra-quenching, or spherical or amorphous powder obtained by mechanical pulverization in air or an inert gas such as nitrogen. The particle size is preferably 1 μm to 100 μm in diameter. The mixing ratio of the carbon material to aluminum or aluminum alloy is 0.01 to 5 parts by weight, preferably 0.1 to 5 parts by weight, per 1 part by weight of aluminum or aluminum alloy.
0.5 to 0.5 parts by weight. When the amount of the carbon material is 0.01 part by weight or less, it is difficult to uniformly disperse the aluminum or aluminum alloy powder (including flakes). For this reason, the carbon material (powder or the like) is aggregated, and the electrical conductivity between the aluminum or aluminum alloy particles becomes poor, and the electrode does not work effectively. Conversely, if it exceeds 5 parts by weight, the aluminum or aluminum alloy powder particles will be thickly covered with the carbon material. Therefore, the contact with the electrolyte is cut off, and the potential becomes unstable or the polarization becomes large.

The electrolyte of the lithium secondary battery of the present invention is a lithium-conductive solid electrolyte (solid or solid at −20 to 60 ° C.), and the solid electrolyte is a salt containing lithium or a lithium-containing salt. It is composed of a polymer containing salt. As a salt containing lithium, LiI, Li ₃ N-LiI-B ₂ O ₃ , L
iI.H ₂ O, Li-β-Al ₂ O ₃ and the like. Examples of the polymer electrolyte containing these include polyethylene oxide in which the lithium salt is dissolved, and a solid electrolyte membrane made of a polyacrylonitrile film containing propylene carbonate in which LiClO ₄ is dissolved. As described below, when mixing the electrolyte in at least one of the positive electrode and the negative electrode, a polyether obtained by adding ethylene oxide and butylene oxide to the polyamine,
A solid electrolyte composition comprising an ion-exchange compound having a layered crystal and a lithium salt is preferably used. The polyether is added to a polyamine in the presence of an alkali catalyst in the form of 10
It can be obtained by subjecting ethylene oxide and butylene oxide to addition reaction at 0 to 180 ° C. and 1 to 10 atm. As the polyamine which is a constituent component of the polyether, polyethyleneimine, polyalkylenepolyamine, or a derivative thereof can be used. Examples of the polyalkylene polyamine include diethylene triamine, triethylene tetramine, hexamethylene tetramine, dipropylene triamine and the like. The number of moles of ethylene oxide and butylene oxide added is 2 to 150 moles per active hydrogen of the polyamine. The molar ratio of ethylene oxide (EO) and butylene oxide (BO) to be added is 80/20 to 10/90.
(= EO / BO). The polyether thus obtained has an average molecular weight of 1,000 to 5,000,000. The polyether is preferably contained in the solid electrode composition at a ratio of 0.5 to 20% by weight. Examples of the compound having an ion-exchangeable layered crystal structure include montmorillonite, hectorite, saponite, clay minerals including silicates such as smectite, zirconium phosphate, phosphates such as titanium phosphate, vanadic acid, antimonic acid, Tungstic acid; or those modified with an organic cation such as a quaternary ammonium salt or an organic polar compound such as ethylene oxide or butylene oxide. In this solid electrolyte composition, polyether, which is one of the constituent components, has a surfactant activity. Therefore, when the composition is mixed with at least one of the positive electrode and the negative electrode, the polyether acts to uniformly disperse the composition and reduce the polarization.

The lithium secondary battery of the present invention can be usually prepared by the following method. For example, first, the components of the positive electrode, the negative electrode, and the electrolyte are respectively mixed and formed into a film. This is laminated in the order of a positive electrode film, an electrolyte film, and a negative electrode film and pressed to obtain a unit cell. The lithium secondary battery of the present invention can be obtained by attaching a copper foil or a lead wire to the positive electrode and the negative electrode of the unit cell of the laminate as required, and putting them in a case. It is recommended that the battery be prepared by mixing the components of the electrolyte with at least one of the positive electrode and the negative electrode.

When the lithium secondary battery of the present invention is charged, Li is released from the S-Li bond of the positive electrode, and an SS bond is formed. Metal lithium is uniformly deposited on the surface of the negative electrode or inside the negative electrode (when the components of the negative electrode and the components of the electrolyte are mixed). Since lithium is directly precipitated from the electrolyte, it is not mixed with impurities such as oxygen. Therefore,
Concentration of current is unlikely to occur even after repeated charging and discharging,
The internal short circuit of the battery is effectively prevented. Since the lithium metal and the electrolyte generated by charging (electrolysis) are extremely well connected electrically, the polarization can be reduced during discharging and a large current can be taken out. Particularly effective results are obtained when the electrolyte is mixed with the positive electrode and / or the negative electrode as described above. At this time, it is particularly advantageous to use a lithium salt, a polyether and a compound having a layered crystal as the electrolyte.

Incidentally, conventional lithium secondary batteries (3 to 3)
It has a high voltage of 4 volts and a high energy density of 100 Wh / Kg or more). Metallic lithium or a lithium alloy is used for the negative electrode, and titanium disulfide and molybdenum disulfide that can reversibly insert and remove lithium ions are used for the positive electrode. A battery using an inorganic substance such as vanadium oxide or cobalt oxide has been proposed. As the electrolyte, a liquid electrolyte in which a lithium salt such as lithium perchlorate or lithium borofluoride is dissolved in an aprotic organic solvent such as propylene carbonate or dimethoxyethane is exclusively used. The ionic conductivity of this liquid electrolyte is two to three orders of magnitude lower than that of aqueous electrolytes used in nickel cadmium secondary batteries or lead-acid batteries. It is necessary to increase the area and make the separator thinner. For this reason, the positive electrode is usually
It is prepared by processing a composition obtained by mixing a powdery positive electrode active component (such as the above titanium disulfide), a conductive material and a binder into a sheet. Besides processing into a sheet, the electrode area of the positive electrode can also be increased by reducing the particle size of the powder or by using a porous powder. However, the only way to obtain a negative electrode having a large area using a soft metallic material such as lithium metal or a lithium alloy which is difficult to process powder is to process it into a thin foil. The positive electrode processed into a thin sheet and the negative electrode are overlapped via a separator such as a polypropylene nonwoven fabric, spirally wound into a battery container, and an electrolyte is poured to obtain the lithium battery. Since metal lithium is used, all operations must be performed in a dry inert gas.

It is important to assemble a lithium secondary battery that the electrodes in contact with the electrolyte be uniform and uniform over the entire surface. The positive electrode is usually composed of a positive electrode active component, a composition including a conductive material and a binder,
If a chemically stable cathode active material is selected and evenly mixed, a relatively homogeneous material can be obtained. However, for the negative electrode, it is difficult to uniformly and homogeneously process a metal lithium or lithium alloy foil having a thickness of several μm to several tens of μm through a multi-stage rolling process. And difficult to assemble uniformly. Therefore, when charging and discharging the battery, the dissolution and deposition reaction of lithium proceeds unevenly in the negative electrode surface, and the unevenness increases as the charge and discharge cycle is repeated.
Eventually, the current is locally concentrated, and lithium precipitates in a dendritic manner, breaks through the separator and connects to the positive electrode, causing an internal short circuit. When an internal short circuit occurs, a large current flows, the battery generates heat, the vapor pressure of the organic solvent increases, the battery ruptures, lithium metal is exposed to the atmosphere, reacts with water, generates hydrogen, and causes ignition. Extremely dangerous.

On the other hand, the lithium secondary battery of the present invention can be prepared without using metallic lithium or a lithium alloy, and therefore does not require complicated operations and is safe. If the battery is stored in a discharged state when the battery is stored, there is substantially no metallic lithium in the battery in the discharged state, so that even if the battery is destroyed, it does not ignite. When the battery is charged, the metallic lithium is uniformly deposited as described above, so that even if the battery is repeatedly charged and discharged, an internal short circuit hardly occurs and the battery is safe. When powdered, fibrous, or porous aluminum or an alloy thereof is used as the material of the negative electrode, the area of the electrode is increased, so that it is not necessary to process it into a thin sheet or film as in the related art.

Example 1 1M (M = mol / dm ³ ) aniline and 5M Na ₂ SO ₄ were dissolved in a sulfuric acid aqueous solution to obtain a sulfuric acid acidic aqueous solution having a pH of 1.0. In this aqueous solution, the electrode of the saturated calomel reference electrode was electrolyzed at a constant potential of 1.2 to 1.5 volt to form a polyaniline film having a fibril structure and a thickness of about 20 μm on the graphite electrode. The graphite electrode having the polyaniline thin film thus obtained was vacuum-dried at 80 ° C. all day and night, and 2,5-dimercapto-1,3,4-thiadiasol was added to 5 mM L
Ag / Ag in dimethylformamide with 1M iClO ₄ dissolved
Electrolysis was performed at a constant potential of +0.8 volt with respect to the potential of the Cl reference electrode to prepare a composite electrode.

In dimethylformamide in which 1M LiClO ₄ is dissolved, the potential of the Ag / AgCl reference electrode is -0.7 to +0.2 volt.
The electrode was electrolyzed at room temperature by linearly increasing and decreasing the potential at a rate of 50 mV / sec. As a result, a current-voltage characteristic shown by a curve A in FIG. 1 was obtained. Next, as a comparative example, electrolysis was similarly performed using a graphite electrode having no polyaniline thin film. As a result, a current-voltage characteristic shown by a curve B in FIG. 1 was obtained. Further, similar electrolysis was performed using a graphite electrode having only a polyaniline thin film. As a result, a current-voltage characteristic shown by a curve C in FIG. 1 was obtained.

In the curve A, the current peak value corresponding to the oxidation-reduction is calculated from the current peak value of the graphite electrode having only polyaniline and the current peak value of the 2,5-dimercapto-1,3,4-thiadiasol, respectively. Is also big. This allows
It can be seen that a large current can be obtained by using the electrode of the present invention using polyaniline and a disulfide compound. Further, in the curve A, the current peak position corresponding to the oxidation-reduction exists between the current peak position of the graphite electrode having only polyaniline and the current peak position of 2,5-dimercapto-1,3,4-thiadiasol. . Among the current peaks corresponding to the oxidation-reduction of 2,5-dimercapto-1,3,4-thiathiazole, a current peak corresponding to the reduction reaction was obtained particularly at around -0.2 volt (the polyaniline thin film was The current peak position was obtained at around -0.6 volt in the graphite electrode without the electrode (curve C). That is, π
It can be seen that the presence of polyaniline, which is an electron conjugated conductive polymer, promotes the redox of 2,5-dimercapto-1,3,4-thiadiazole. As described above, in the current-voltage characteristic curve B obtained with the graphite electrode having no polyaniline thin film, the oxidation peak and the reduction peak corresponding to the oxidation-reduction of 2,5-dimercapto-1,3,4-thiadiasol are shown. -Potential difference from
Near 0.6volt. As described above, in the graphite electrode having no polyaniline thin film, the oxidation-reduction is quasi-reversible, and the reaction speed is slow. For example, when this electrode is used as the positive electrode of a battery, the voltage difference between charging and discharging is as large as 0.6 volt or more, so that charging and discharging with a large current greatly reduces the efficiency of the battery.

Example 2 Aniline was chemically polymerized in an acidic aqueous solution by using cupric borofluoride as an oxidizing agent. As a result, a porous polyaniline powder having an average particle diameter of 0.3 μm and having a fibril structure was obtained.
1 part by weight of this polyaniline powder and 2,5-dimercapto-1,3,4
-1 part by weight of thiazazole powder and 0.1 part by weight of carbon black were mixed with low-density polyethylene (trade name: Exelen V).
L-200, density = 0.9, manufactured by Sumitomo Chemical Co., Ltd.) was mixed in the dissolved toluene. Next, the mixture was applied on a 200-mesh stainless steel net and dried to obtain a sheet-like composite electrode having a thickness of about 100 μm.

The composite electrode was used as a positive electrode, and a propylene carbonate in which 1M LiClO ₄ was dissolved was used as a solid electrolyte membrane.
A solid battery A having a size of 28 × 28 mm was formed by using a polyacrylonitrile film having a thickness of about 70 μm and containing lithium metal as a negative electrode.

The battery was charged at room temperature with a constant voltage of 3.6 volts for 17 hours, and then charged at 1 μA, 10 μA, 100 μA.
A, 500 μA and 1 mA were discharged for 3 seconds each. The current-voltage characteristics were evaluated by recording each battery voltage. The result is shown in curve (a) of FIG. As a comparative example, a sheet-like electrode having a thickness of about 100 μm and containing no polyaniline powder was prepared using the same method. Battery B was configured by using this electrode. The current-voltage characteristics of this battery are shown in curve (b) of FIG. Battery A has a smaller polarization than battery B, and a larger current can be obtained by using battery A.

In these examples, by using an electrode in which a disulfide compound and a π-electron conjugated conductive polymer were combined, it was difficult to use a large current at the time of using a conventional disulfide compound. Electrolysis is possible.
By using this composite electrode as a positive electrode and using metallic lithium as a negative electrode, charging and discharging with a large current can be expected.
A secondary battery having a high energy density can be formed.

In this embodiment, only the battery using the composite electrode is shown. However, by using the composite electrode of the present invention as a counter electrode, a biochemical sensor such as an electrochromic device having a fast coloring / fading speed, a glucose sensor having a fast response speed, and an electrochemical analog memory having a fast writing / reading speed are constituted. You can also.

Example 3 2-pyrrolecarboxylic acid 11
g (0.1 mol) in 200 ml of acetonitrile
After cooling, bromine (16 g, 0.1 mol) was added dropwise to the solution. After stirring this solution for 60 minutes, it was neutralized by adding a 20% aqueous sodium carbonate solution. Ether was added to this solution, and the aqueous layer was extracted with ether. After the extracted ether solution was dried, the ether was removed. As a result, 3,
A mixture of 2-pyrrolecarboxylic acid with 2-substituted bromine and 2-substituted 2-pyrrolecarboxylic acid with 1-substitution was obtained in the 4- and 5-positions. 6 g of this mixture is xylene 20
Dissolved in a mixed solution of 0 ml and 10 ml of ethanolamine.
Heated to reflux for an hour. Then washed with 30% acetic acid aqueous solution,
The organic layer was separated and dried. Xylene was removed from this solution to obtain 3 g of a mixture of 2-substituted bromopyrrole and 1-substituted bromopyrrole. Redissolve this mixture in xylene,
Separation was performed using a silica gel column to obtain 1 g of 3-bromopyrrole.

The thus obtained 3-bromopyrrole was dissolved in an aqueous sulfuric acid solution, and the amount of 3-bromopyrrole was 1 mol / mol.
1 and 5 mol / l of a sulfuric acid acidic aqueous solution having a pH of 1.0 were obtained, respectively. In this aqueous solution, by electrolyzing at a constant potential of 1.2 to 1.5 V with respect to the potential of the saturated calomel reference electrode, a poly-3-
A bromopyrrole film was formed on the graphite electrode. The thus obtained graphite electrode having a poly-3-bromopyrrole thin film was vacuum-dried at 80 ° C. overnight. 1 g (0.01 mol) of this polybromopyrrole was reacted with 0.8 g (0.01 mol) of thiourea to introduce a mercapto group, and further, in the presence of chlorine,
By reacting 1.2 g (0.01 mol) of 5-dimercapto-1,3,4-thiadiazole, an electrode composed of polypyrrole into which disulfide represented by the following formula was introduced was obtained.

[0044]

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The potential was linearly increased and decreased at a rate of 50 mV / sec between -0.7 and +0.2 V with respect to the potential of the Ag / AgCl reference electrode in dimethylformamide in which 1 mol / l of LiClO ₄ was dissolved. The electrodes were electrolyzed at room temperature. As a result, a current-voltage characteristic shown by a curve A in FIG. 3 was obtained.

As a comparative example, the potential of the Ag / AgCl reference electrode was measured using a graphite electrode in dimethylformamide in which 2,5-dimercapto 1,3,4-thiathiazole was dissolved at 0.05 mol / l and LiClO ₄ was dissolved at 0.5 mol / l. Was electrolyzed at a constant potential of + 0.8V. The electrode having no polypyrrole was similarly electrolyzed to obtain a current-voltage characteristic shown by a curve B in FIG. further,
A graphite electrode having only a polypyrrole thin film was prepared, and the same electrolysis was performed using the same, whereby a current-voltage characteristic shown by a curve C in FIG. 3 was obtained. In the curve A, the current peak value corresponding to the oxidation-reduction is larger than the current peak value of the graphite electrode having only polypyrrole and the current peak value of 2,5-dimercapto-1,3,4-thiadiazole. This indicates that a large current can be obtained by using the electrode of the present invention using polypyrrole and a disulfide compound. In the curve A, the current peak value corresponding to the oxidation-reduction exists between the current peak position of the graphite electrode having only polypyrrole and the current peak position of 2,5-dimercapto-1,3,4-thiadiasol. I do. Among the current peaks corresponding to the oxidation-reduction of 2,5-dimercapto-1,3,4-thiadiazole, the current peak position corresponding to the reduction reaction is particularly around -0.2 V (when a graphite electrode having only polypyrrole is used. -0.6V
Is). That is, by using polypyrrole which is a π-electron conjugated conductive polymer in which 2,5-dicarcapto-1,3,4-4 thiadiazole is incorporated, the 2,5-dimercapto-1,
It can be seen that the redox of 3,4-thiadiazole is promoted.

In the current-voltage characteristic curve B obtained from the graphite electrode having no polypyrrole thin film, 2,5-dimercapto-
The potential difference between the oxidation peak and the reduction peak, which corresponds to the redox of 1,3,4-thiadiazole, is near 0.6 V. In such an electrode, the oxidation-reduction is quasi-reversible and the reaction speed is slow. For example, when this electrode is used as the positive electrode of a battery, the voltage difference between charging and discharging is as large as 0.6 V or more, so that charging and discharging with a large current results in a battery with poor charge / discharge efficiency.

In this embodiment, the case where pyrrole is used as a monomer capable of forming a conductive polymer has been described. However, the present invention is not limited to this,
It is needless to say that the same effect can be obtained by using another monomer such as aniline.

As is clear from the above description of the embodiment, in this embodiment, an electrode can be obtained by introducing a disulfide compound into a conductive polymer. By using this electrode, it is possible to perform electrolysis with a large current, which is difficult when an electrode composed of only a conventional disulfide compound is used. By using this electrode as a positive electrode and using lithium metal as a negative electrode, a secondary battery having high energy density, which can be charged and discharged with a large current, can be formed.

By using the electrode of the present invention as a counter electrode,
In addition to the battery, an electrochromic device having a high coloring / fading speed, a biochemical sensor such as a glucose sensor having a fast response speed, an electrochemical analog memory having a fast writing / reading speed, and the like can be obtained.

Example 4 (1) Synthesis of 1,8-disulfide naphthalene 60 g of 1-aminonaphthalene-8-sulfonic acid (0.27 g)
mol) was mixed with water in a mortar to form a paste. This paste was transferred to a flask, and 200 ml of water and 20 ml of sulfuric acid were added. To this, a solution of 30 g (0.43 mol) of sodium nitrate dissolved in 100 ml of water was added over about 30 minutes while stirring. The temperature of the obtained solution is -10-
The polymerization reaction was carried out for about one and a half hours while maintaining the temperature at 15 ° C. The diazonium salt formed was filtered and the reaction solution was washed with 100 ml of cold water. Then, 200 ml of sodium disulfide solution was added to the salt. The solution was left at room temperature for 3 hours. Hydrochloric acid was added dropwise thereto to adjust the pH to 7.5, and the precipitated sulfur was removed. Thus, 45 g of 8,8'-dithiodi-1-naphthalene sulfate sodium salt was obtained. This salt was put in cold water, and then 30 g (0.14 mol) of phosphorus pentachloride was slowly added to react. The reaction solution was returned to room temperature and left for 30 minutes. The reaction was washed with benzene until the reaction was decolorized, and the filtrate obtained by filtration was concentrated to obtain a solid. This was recrystallized using methanol. Thus, 16 g of naphtho [1,8-c, d] -1,2-dithiol 1,1 dioxide was obtained. 16 g of this compound was reacted for 1 hour in a hydrochloric acid solution containing zinc powder to obtain 10 g of 1,8-disulfide naphthalene. (2) Preparation of composite electrode of 1,8-disulfide naphthalene and polyaniline A solution of 0.5 M Na ₂ SO ₄ (adjusted to pH 1) and aniline 0.1 M was added to the solution of 1,1 obtained in (1). 8-Disulfide naphthalene was added to 10 mmol / l. This solution was applied to the saturated calomel reference electrode at a potential of 1.
By electrolysis at a constant potential of 2 V, a polyaniline-1,8-disulfide naphthalene composite film having a fibril structure and a thickness of about 20 μm was formed on the graphite electrode. (3) the cyclic voltammetry LiClO ₄ in dimethylformamide was dissolved 1M, -0.7~ to the potential of the Ag / AgCl reference electrode
The potential was linearly increased and decreased at a rate of 50 mV / sec between +0.2 V, and the electrode obtained in (2) was electrolyzed at room temperature. As a result, a current-voltage characteristic shown by a curve A in FIG. 4 was obtained. As a comparative example, 1,8-disulfide naphthalene was added at 10 mol / l.
And LiClO ₄ in dimethylformamide in which 0.5 mol / l is dissolved, the potential is linearly increased or decreased at a rate of 50 mV / sec between −0.7 to +0.2 V with respect to the potential of the Ag / AgCl reference electrode, The graphite electrode was electrolyzed. As a result, a current-voltage characteristic shown by a curve B in FIG. 4 was obtained. Further, the same electrolysis was performed on a graphite electrode having only a polyaniline polymer film, and a current-voltage characteristic shown by a curve C in FIG. 4 was obtained.

In the curve A, the current peak value corresponding to the redox is larger than the current peak value of the graphite electrode having only the polyaniline polymer film and the current peak value of 1,8-disulfide naphthalene. This indicates that a large current can be obtained by using the electrode of the present invention using the polyaniline polymer film and the disulfide compound. Further, in the curve A, the current peak position corresponding to the redox exists between the current peak position of the graphite electrode having only the polyaniline polymer film and the current peak position of 1,8-disulfide naphthalene. Of the current peaks corresponding to the oxidation-reduction of 1,8-disulfide naphthalene, the position of the current peak particularly corresponding to the reduction reaction is −
Around 0.2 V (-0.1 in the 1,8-disulfide naphthalene electrode without polyaniline (curve B)).
6V). It can be seen that the redox of 1,8-disulfide naphthalene is promoted by the presence of the thiophene derivative polymer, which is an ion-electron mixed conductor polymer.

As described above, in the current characteristics (curve B) obtained from the graphite electrode having no polyaniline, 1,
The potential difference between the oxidation peak corresponding to the oxidation-reduction of 8-disulfide naphthalene and the reduction peak is close to 0.6V. In such an electrode, oxidation-reduction is quasi-reversible and the reaction speed is slow. For example, when this electrode is used as the positive electrode of a battery, the voltage difference between charge and discharge is as large as 0.6 V or more, so that a battery with a large decrease in efficiency when charged and discharged with a large current can be obtained.

In this embodiment, the case where polyniline is used has been described. However, similar effects can be obtained by using other conductive polymers. In this embodiment, electrolytic polymerization is used as a polymerization method, but a composite film can be formed by ordinary oxidation polymerization. Further, needless to say, the same effect can be obtained even when the polymer film of the present invention is pulverized and mixed with a current collector.

The reversible electrode of this embodiment is used for applications other than batteries, such as an electrochromic device having a high color development / fading speed by using the electrode as a counter electrode, a biochemical sensor such as a glucose sensor having a high response speed, and writing / reading. It is used for high-speed electrochemical analog memories.

As is clear from the above description of the embodiment,
According to the present invention, since a reversible electrode was formed by using a compound having a disulfide bond in the molecule and a conductive polymer, it was difficult with a conventional electrode formed only of a disulfide compound, and a large current was used. Can be electrolyzed. By using this electrode for the positive electrode and using metal lithium for the negative electrode, a secondary battery having high energy density and capable of charging and discharging with a large current can be formed.

Example 5 84 g (1 mol) of thiophene and 100
ml of carbon tetrachloride were mixed and cooled to 0 ° C. In addition, 500
A solution of g (3.1 mol) of bromine in 300 ml of carbon tetrachloride was gradually added. After all of them were mixed, carbon tetrachloride was distilled off, 15 g of sodium hydroxide was added, and the mixture was heated on a steam bath for 4 hours. After the alkali layer was separated and removed from this mixture and the residue was dried, a mixture of mono-, di- and tri-substituted thiophene bromides was obtained by distillation. This mixture was dissolved in xylene, fractionated by using a silica gel column, and 2,2,3-tribromothiophene was added in an amount of 30 g.
Obtained.

The thus obtained 32 g (0.1 mol) of 2,2
2,3-tribromothiophene and 6.5 g (0.2 mol) of zinc metal
The mixture was reacted with 6 g (0.2 mol) of acetic acid to obtain 3-bromothiophene.

8.0 g (0.05 mol) of 3-bromothiophene thus obtained was reacted with 4 g of thiourea in acetonitrile to obtain 2.0 g (0.01 mol) of 3-mercaptothiophene. This 3-mercaptothiophene was dissolved in chlorine in 2,5-dimercapto-1,3,4-thiadiazole 1.2 g (0.01 mol
l) to give thiophene into which disulfide group was introduced.

In propylene carbonate, the thiophene derivative (1 mol / l) thus obtained is used as a monomer, and lithium perchlorate is used as a supporting electrolyte, so that the potential of the saturated calomel reference electrode is 1.2 to 1.5. Electrolysis was performed at a constant potential of V. Thus, a thiophene derivative polymer film having a fibril structure and having a thickness of about 20 μm was formed on the graphite electrode.

In dimethylformamide in which 1M of LiClO ₄ is dissolved, the potential of the Ag / AgCl reference electrode is -0.7 to +0.
The potential was linearly increased and decreased at a rate of 50 mV / sec between 2 V, and the electrode was electrolyzed at room temperature. As a result, a current-voltage characteristic referred to by a curve A in FIG. 5 was obtained. As a comparative example, 2,5-dimercapto 1,3,4-thiathiazole was 0.05 mol / l, and LiClO ₄ was 0.5 mol / l.
l In a dissolved dimethylformamide, constant potential electrolysis was performed at +0.8 V with respect to the potential of the Ag / AgCl reference electrode, and a graphite electrode without polythiophene was similarly electrolyzed. As a result, a current-voltage characteristic shown by a curve B in FIG. 5 was obtained. Further, similarly, a graphite electrode having only a polythiophene thin film was electrolyzed. As a result, a current-voltage characteristic shown by a curve C in FIG. 5 was obtained.

In the curve A, the current peak value corresponding to the oxidation-reduction is smaller than the current peak value of the graphite electrode having only polythiophene and the current peak value of 2,5-dimercapto-1,3,4-thiadiasol. Is also big. This shows that a large current can be obtained by using the electrode of the present invention using polythiophene and a disulfide compound.
Further, in the curve A, the current peak position corresponding to the redox exists between the current peak position of the graphite electrode having only polythiophene and the current peak position of 2,5-dimercapto-1,3,4-thiadiasol. I do. Among the current peaks corresponding to the oxidation-reduction of 2,5-dimercapto-1,3,4-thiaciasol, the current peak position corresponding to the reduction reaction is particularly around -0.2 V (2,5-dimercapto without polythiophene) For a 1,3,4-thiazolazole electrode (curve B) it is -0.6V). It can be seen that the presence of the conductive polymer, polythiophene, promotes the redox of 2,5-dimercapto-1,3,4-thiadiazole.

As described above, in the current-voltage characteristic curve B obtained with the graphite electrode having no polyaniline thin film,
The potential difference between the oxidation peak and the reduction peak corresponding to the redox of 2,5-dimercapto-1,3,4-thiadiazole is close to 0.6 V. In such an electrode, oxidation-reduction is quasi-reversible and the reaction speed is slow. For example, when this electrode is used as the positive electrode of a battery, the charge / discharge voltage difference is as large as 0.6 V or more, so that a battery with poor charge / discharge efficiency when performing charge / discharge with a large current is obtained.

In this embodiment, the case where polythiophene is used has been described. However, the present invention is not limited to this, and similar effects can be obtained by using other conductive polymers. Further, needless to say, the same effect can be obtained even if the polymer film of this example is pulverized and mixed with a current collector.

As is clear from the above description of the embodiment,
According to the present invention, a polymer is obtained by polymerizing a monomer obtained by introducing a disulfide compound into a monomer capable of forming a conductive polymer, and the polymer is used as a main component to constitute an electrode. Electrolysis with a large current becomes possible, which was difficult with an electrode composed of only a disulfide compound. By using this electrode as the positive electrode and using metallic lithium as the negative electrode, charging and discharging with a large current is possible.
A secondary battery having a high energy density can be configured.

The reversible electrode of this embodiment is used for applications other than a battery, such as an electrochromic device having a high color development / fading speed, a biochemical sensor such as a glucose sensor having a high response speed, and a writing / reading device by using the electrode as a counter electrode. Used for high-speed electrochemical analog memory.

Example 6 (1) Oxidative polymerization of 2-mercapto-2-thiazoline (preparation of dimer) 60 g (0.5 mol) of 2-mercapto-2-thiazoline was dissolved in 100 ml of dimethyl sulfoxide. Oxygen was blown into the solution, and the solution was allowed to stand at room temperature for one day and night to allow oxidative polymerization. The reaction solution is subjected to preparative thin-layer chromatography,
The desired dimer of 2-mercapto-2-thiazoline was converted to 4
8 g (0.2 mol) were obtained. (2) Preparation of composite electrode of 2-mercapto-2-thiazoline dimer and polyaniline A 2-mercapto-2- solution was added to a solution containing 0.5 M Na ₂ SO ₄ (adjusted to pH = 1) and 0.1 M aniline. The 2-mercapto-2-thiazoline dimer obtained in section (1) of this example was added so that the thiazoline dimer was 10 mmol / l. This solution was applied to the saturated calomel reference electrode at a potential of 1.
By electrolyzing at a constant potential of 2 to 1.5 V, polyaniline-2- having a fibril structure and having a thickness of about 20 μm was obtained.
A mercapto-2-thiazoline dimer composite film was formed on a graphite electrode.

For comparison, 0.5 M Na ₂ SO ₄ (pH =
1) and 0.1 M aniline in a solution containing 2-mercapto-2-thiazoline at 10 mmol / l.
An attempt was made to create an electropolymerized membrane by adding -mercapto-2-thiazoline and electrolyzing at a constant potential of 1.2 to 1.5 V with respect to the potential of the saturated calomel reference electrode, but no composite membrane was created. . (3) Cyclic voltammetry At room temperature, the potential of the Ag / AgCl reference electrode in dimethylformamide in which 1 M of LiClO ₄ was dissolved was −
The polyaniline-2-mercapto-2-thiazoline dimer composite electrode obtained in the item (2) of the present example was obtained by linearly increasing and decreasing the potential at a rate of 50 mV / sec between 0.7 and +0.2 V. Was electrolyzed. As a result, a current-voltage characteristic curve indicated by a curve A in FIG. 1 was obtained. As a comparative example, 2-mercapto-
2-thiazoline 10 mmol / l, LiClO ₄ 0.5 mol
Using a graphite electrode in dissolved dimethylformamide / l, -0.7 to +0.2 with respect to the Ag / AgCl reference electrode.
The potential was linearly increased and decreased at a rate of 50 mV / sec between V and electrolysis was performed. As a result, a current-voltage characteristic curve shown by a curve B in FIG. 6 was obtained. Further, a graphite electrode having only a polyaniline polymer film was electrolyzed by the same method. as a result,
A current-voltage characteristic curve shown by a curve C in FIG. 8 was obtained.

In the curve A, the current peak value corresponding to the oxidation-reduction is larger than the current peak value of the graphite electrode having only the polyaniline polymer film and the current peak value of 2-mercapto-2-thiazoline. This indicates that a large current can be obtained by using the electrode according to the method of the present invention using a polyaniline polymer film and a disulfide compound. Further, in the curve A, the current peak position corresponding to the oxidation-reduction is different from the current peak position of the graphite electrode having only the polyaniline polymer film in 2-mercapto-
It exists between the current peak position of 2-thiazoline. 2
-Among the current peaks corresponding to the oxidation-reduction of mercapto-2-thiazoline, the position of the current peak particularly corresponding to the reduction reaction is around -0.2 V (only the polyaniline polymer film having no 2-mercapto-2-thiazoline is used. (-0.6 V in the graphite electrode (curve B)). It can be seen that the presence of polyaniline promotes the redox of 2-mercapto-2-thiazoline.

In the current-voltage characteristics (curve B) obtained with the graphite electrode having no polymer as described above, the potential difference between the oxidation peak corresponding to the oxidation-reduction of 2-mercapto-2-thiazoline and the reduction peak was found. Near 0.6V. In such an electrode, oxidation-reduction is quasi-reversible and the reaction speed is slow.
For example, when this electrode is used as the positive electrode of a battery, the voltage difference between charge and discharge is as large as 0.6 V or more, so that a battery with a large decrease in efficiency when charged and discharged with a large current can be obtained. (4) Charging / discharging cycle characteristics A battery was prepared with the following configuration. As the working electrode, the polyaniline-2-mercapto-2 obtained in the item (2) of this example was used.
Using a thiazoline dimer composite electrode and L as a reference electrode
i-line was used. A Li foil was used as a counter electrode, and a dimethylformamide solution in which 1 M of LiClO ₄ was dissolved was used as an electrolyte solution. Using this battery, a charging potential of 4.0 V and 15
After charging for 2 hours, final voltage 2.0V, discharge current 0.5mA
A charge / discharge cycle characteristic test was performed under the following conditions. As a result, a charge / discharge cycle characteristic curve shown by a curve A in FIG. 7 was obtained. In FIG. 7, the number of cycles is shown on the horizontal axis, and the discharge capacity after each charge / discharge cycle test when the discharge capacity in the first cycle is 100 is shown on the vertical axis. As a comparative example, a similar battery was constructed using a composite electrode prepared by mixing polyaniline, 2-mercapto-2-thiazoline and polyethylene oxide at a weight ratio of 3: 1: 1 as a working electrode. Using this battery, a charge-discharge cycle characteristic test was performed under the same conditions. As a result, curve B in FIG.
A charge / discharge cycle characteristic curve referred to in Table 1 was obtained.

In the charge / discharge cycle characteristic curve (curve A) of this embodiment, the charge / discharge cycle characteristic is 50% of the initial capacity at 50 cycles, and the charge / discharge cycle characteristic is excellent. On the other hand, in the charge / discharge cycle characteristic curve (curve B) of the comparative example, the charge / discharge efficiency decreases from about 10 cycles.

In this embodiment, the case where polyaniline is used as the conductive polymer has been described. However, similar effects can be obtained by using the other conductive polymers described above. Although the case where electrolytic polymerization is used as the polymerization method has been described, a composite film can be formed using ordinary oxidative polymerization. It is obvious that the same effect can be obtained even if the polymer film of this example is pulverized and mixed with the current collector.

In this example, 2-mercapto-2-thiazoline was used as the compound having a thiol group, but the same reaction can be carried out using another compound having a thiol group. Further, an electrode can be formed using a compound having two or more thiol groups. For example, a copolymer is prepared by oxidatively copolymerizing a compound having a plurality of thiol groups in a molecule and a compound having one thiol group, and apparently a polymer having a protected thiol group (multimer ) Can be prepared and coexist during electrolytic polymerization of a monomer capable of forming a conductive polymer.

As is clear from the above description of the embodiment,
A conventional disulfide compound was used by using an electrode mainly composed of a conductive polymer and a dimer in which a compound having a thiol group was disulfide-bonded between molecules according to the method of the present invention. Electrolysis with a large current, which has been difficult with a reversible electrode, becomes possible. This electrode can be made by electrolytic polymerization or chemical oxidation polymerization. By using this electrode as a positive electrode and using metallic lithium as a negative electrode, a high energy density secondary battery capable of charging and discharging with a large current can be formed.

The electrodes according to the method of this embodiment may be used for applications other than batteries, such as an electrochromic device having a high color developing / fading speed, a biochemical sensor such as a glucose sensor having a high response speed, and a writing / reading device. A high-speed electrochemical analog memory can be obtained.

(Example 7) Polyethyleneimine containing 10 N atoms in the molecule was replaced with ethylene oxide (E
O) and butylene oxide (BO) were added such that the ratio of EO to BO was 30/70. The polyether having an average molecular weight of 180,000 thus obtained was dissolved in acetonitrile to prepare a 20% by weight polyether solution. Further, LiCF ₃ SO ₃ as a lithium salt was dissolved in the polyether solution at a ratio of 10% by weight. The solid content (polyether, LiCF ₃
Γ-zirconium phosphate powder having an average particle size of 15 μm was added so that the total content of SO ₃ and γ-zirconium phosphate was 30% by weight. This solution was stirred and mixed at 40 ° C. for 24 hours to obtain an electrolyte slurry. The electrolyte slurry was applied on a smooth Teflon plate by using a doctor blade. This was dried for 1 hour in a dry argon gas stream at 130 ° C., and further vacuum-dried for 5 hours to obtain an electrolyte sheet having a size of 80 × 80 mm and a thickness of 85 μm.

Next, the electrolyte slurry 1 having the same composition as above was used.
0.1 part by weight of artificial graphite powder having a degree of graphitization of 48% and an average particle size of 2 μm, 2 parts by weight of 2,5-dimercapto-1,3,4-lithium thiolate and 0. 5 parts by weight were added and mixed to obtain a positive electrode slurry. The polyaniline powder is 1
PH = 1.0 containing ^{M (M = mol / dm 3} ) of aniline and Na ₂ SO ₄ with 5M of
In a sulfuric acid aqueous solution at a constant potential of 1.2 to 1.5 volts with respect to the potential of the saturated calomel reference electrode. This positive electrode slurry was applied on a smooth Teflon plate by using a doctor blade. This was dried for 1 hour in a dry argon stream at 130 ° C., and further vacuum-dried for 5 hours to obtain a 80 ×
A positive electrode sheet composition having a thickness of 80 mm and a thickness of 160 μm was obtained.

Further, 1 part by weight of a metal aluminum powder having an average particle size of 18 μm and a purity of 99.98% and an artificial graphite having a graphitization degree of 48% and an average particle size of 2 μm were added to a polyether solution having the same composition as described above. A mixed powder with 0.1 part by weight of the powder was added so that the solid content became 50%.
The mixture was mixed for 4 hours to obtain a negative electrode slurry. The electrode composition slurry was obtained by mixing the negative electrode slurry and the electrolyte slurry having the same composition in an alumina ball mill for 24 hours so that the solid content ratio was 1: 2. The electrode composition slurry was applied on a smooth Teflon plate by using a doctor blade. This was dried for 1 hour in a dry argon gas stream at 130 ° C., and further vacuum-dried for 5 hours to obtain a size of 80 × 80 mm and a thickness of 18 mm.
A negative electrode sheet of 0 μm was obtained.

A 50 μm-thick carbon sheet formed of a mixture mainly composed of a fluororesin and carbon powder, a positive electrode sheet, an electrolyte sheet, a negative electrode sheet, and a carbon sheet (the same composition as above) are laminated in this order. , Temperature 150
Thermocompression bonding was performed under the conditions of a temperature of 200 ° C. and a pressure of 200 kg / cm ² . This was cut into a size of 28 × 28 mm to obtain a unit cell. Through a 10 μm-thick thermally conductive conductive film mainly composed of synthetic rubber and carbon fiber, a thickness of 30 μ serving also as an electrode lead
m of copper foil was thermally bonded to both sides of the unit cell. Further, the whole unit cell was sealed with a laminated film composed of a polyethylene terephthalate film having a thickness of 38 μm, an aluminum foil having a thickness of 50 μm, and a polyethylene film having a thickness of 50 μm, to obtain a battery A.

Next, for comparison, the battery B was prepared by the following method.
Was prepared. First, in acetonitrile in which 1 mol of LiBF ₄ was dissolved, electrolytic oxidation was performed at a potential of 1.0 V with respect to the potential of the Ag / AgCl electrode to obtain a disulfide compound containing no lithium ion. Battery A was prepared except that this was used in place of 2,5-dimercapto-1,3,4-lithium thiolate and a lithium alloy plate having an aluminum content of 30 atomic% and a thickness of 200 μm was used for the negative electrode. Battery B was obtained in the same manner as described above.

Next, another lithium secondary battery of the present invention was prepared by the following method. 2,5-dimercapto-1,3,4-lithium thiolate powder 1 part by weight, polyaniline powder 0.2 part by weight,
0.1 parts by weight of carbon black, 1 part by weight of LiI-Li ₃ NB ₂ O ₃ (molar ratio = 1: 1: 1) powder, and low-density polyethylene 6
And a toluene solution containing by weight. The polyaniline powder is a porous polyaniline powder having a fibril structure with an average particle diameter of 0.3 μm, which is synthesized by chemically polymerizing aniline by using cupric borofluoride as an oxidizing agent in an acidic aqueous solution. is there. The low-density polyethylene is Exelen VL-200 (trade name; density = 0.9, manufactured by Sumitomo Chemical Co., Ltd.). When the mixture is dried, the content of the low-density polyethylene is 5% by volume.
Was added to be Next, this solution was applied on a 200 mesh nylon net and dried to obtain a positive electrode sheet having a size of 80 × 80 mm and a thickness of about 155 μm.

Next, LiI-Li ₃ NB ₂ O ₃ powder and a 6% by weight toluene solution of low density polyethylene were mixed so that the content of the low density polyethylene when dried was 35% by volume. Next, the solution was applied on a 200-mesh nylon net and dried to a size of 80 × 8.
An electrolyte sheet having a thickness of 0 mm and a thickness of about 90 μm was obtained.

Further, 1 part by weight of metal aluminum powder
0.1 parts by weight of graphite powder and LiI-Li _ThreeN-B_TwoO_ThreePowder 0.
5 parts by weight and the same low-density polyethylene toluene
Low-density polyethylene content
Was mixed so as to be 7.5% by volume. The above metal Al
Minium has an average particle size of 18 μm and a purity of 99.
98% metallic aluminum powder, graphite powder
Is artificial black having a degree of graphitization of 90% and an average particle size of 0.6 μm.
Lead powder was used. Next, apply this solution to a 200 mesh nail
Apply on a lonnet and dry to size 8
A negative electrode sheet having a size of 0 × 80 mm and a thickness of about 190 μm was obtained.
These positive electrode sheet, electrolyte sheet, and negative electrode sheet
Was used to obtain a battery C in the same manner as described above.

Next, for comparison, a battery D was prepared by the following method. First, electrolytic oxidation was performed at a potential of 1.0 V with respect to the potential of the Ag / AgCl electrode in acetonitrile in which 1 mol of LiBF ₄ was dissolved to obtain a disulfide compound containing no lithium ion. This is used in place of 2,5-dimercapto-1,3,4-lithium thiolate, and the anode has an aluminum content of 30 atomic%.
A battery D was obtained in the same manner as in the preparation of the battery C, except that a lithium alloy plate having a thickness of 200 μm was used.

The batteries A and B thus prepared were
After applying a constant voltage of 3.6 volts to the batteries C and D at 65 ° C. for 17 hours, 1 μA, 10 μA, 10
Discharge was performed for 3 seconds at a current of 0 μA, 500 μA, and 1 mA, respectively. The current-voltage characteristics were evaluated by recording the battery voltage at that time. The result is shown in FIG. Comparing the current-voltage characteristics of the batteries A and C with the current-voltage characteristics of the batteries B and D of the comparative example, it can be seen that the former has a smaller voltage drop and a larger current can be obtained.

As is apparent from the above description of the embodiment, in the lithium secondary battery of the present invention, a lithium thiolate compound having a sulfur-lithium ion bond, which forms a sulfur-sulfur bond by electrolytic oxidation, A positive electrode mainly composed of a mixture with an electron conjugated conductive polymer is used, and a composition mainly composed of metallic aluminum or an alloy thereof and a carbon material is used as a negative electrode. Therefore, lithium secondary battery can be safely assembled without handling chemically active metal lithium or its alloy when assembling the battery. In the lithium secondary battery assembled in this manner, by storing the battery in a discharged state, there is substantially no metallic lithium in the battery, and therefore, there is no ignition when the battery is destroyed. Further, by using the lithium battery of the present invention, a larger current can be obtained as compared with a conventional battery using lithium metal or an alloy thereof as a negative electrode.

Example 8 84 g (1 mol) of thiophene and 100
ml of carbon tetrachloride and cooled to 0 ° C. In addition, 5
A solution of 00 g (3.1 mol) of bromine in 300 ml of carbon tetrachloride was slowly added. After all of these were mixed, carbon tetrachloride was distilled off, 15 g of sodium hydroxide was added, and the mixture was heated on a steam bath for 4 hours. The alkali layer was separated and removed from the mixture, and the residue was dried and distilled to obtain 1 residue.
A mixture of substituted, disubstituted and trisubstituted thiophene bromides was obtained. This mixture was dissolved in xylene and fractionated by using a silica gel column to obtain 30 g of 2,2,3-tribromothiophene.

The thus obtained 32 g (0.1 mol) of 2,2,3
-Tribromothiophene and 6.5 g (0.2 mol) of zinc metal and 6 g
(0.2 mol) acetic acid was mixed and reacted to obtain 3-bromothiophene.

To 8.0 g (0.05 mol) of 3-bromothiophene
g of thiourea was added and reacted in acetonitrile to obtain 2 g (0.01 mol) of 3-mercaptothiophene. The 3-mercaptothiophene was reacted with 0.8 g (0.01 mol) of 1-propylmercaptan in chlorine to obtain thiophene into which disulfide was introduced.

The thiophene derivative (1 mol / l) thus obtained was used as a monomer to form propylene carbonate.
In this case, by using lithium perchlorate as a supporting electrolyte, the potential of the saturated calomel reference electrode is 1.
Electrolysis was performed at a constant potential of 2 to 1.5 volts. As a result, a conductive polymer containing a lithium thiolate group was obtained.

Next, an electrolyte sheet having the same composition and the same size as that of the battery A of Example 7 was prepared.

Next, the electrolyte slurry (battery A of Example 7)
1 part by weight, 0.1 part by weight of artificial graphite powder having a degree of graphitization of 48% and an average particle size of 2 μm, and a conductive material containing the above-mentioned lithium thiolate group. And 2 parts by weight of a conductive polymer to obtain a positive electrode slurry. The positive electrode slurry was applied on a smooth Teflon plate by using a doctor blade. This was dried for 1 hour in a dry argon stream at 130 ° C., and further dried for 5 hours.
By vacuum drying for hours, the size is 80x80mm,
A positive electrode sheet having a thickness of 160 μm was obtained.

Next, a negative electrode sheet having the same composition and the same size as that of the battery A of Example 7 was prepared.

Using the above-mentioned positive electrode sheet, electrolyte sheet and negative electrode sheet, a battery A of this example was prepared in the same manner as in the preparation of the battery A of Example 7.

Next, for comparison, a battery B was prepared by the following method. First, in acetonitrile in which 1 mol of LiBF4 was dissolved, electrolytic oxidation was performed at a potential of 1.0 V with respect to the potential of the Ag / AgCl electrode to obtain a disulfide compound containing no lithium ion. The above battery A was used except that this was used in place of the above-mentioned conductive polymer containing a lithium thiolate group, and a lithium alloy plate having a thickness of 200 μm and an aluminum content of 30 atomic% was used for the negative electrode. Battery B was obtained in the same manner as in the preparation.

Next, another lithium secondary battery of the present invention was prepared by the following method. The thiophene derivative having a disulfide group synthesized above was chemically polymerized by using cupric borofluoride as an oxidizing agent in an acidic aqueous solution.
As a result, a porous thiophene derivative polymer having an average particle diameter of 0.3 μm and having a fibril structure was synthesized. 0.2 parts by weight of a polymer powder of this thiophene derivative, 0.1 parts by weight of carbon black, and LiI-Li ₃ NB ₂ O ₃
(Molar ratio = 1: 1: 1) 1 part by weight of powder and a toluene solution containing 6% by weight of low-density polyethylene were mixed. The low-density polyethylene was Exelen VL-200 (trade name; density = 0.9, manufactured by Sumitomo Chemical Co., Ltd.), and was added so that the content of the low-density polyethylene was 5% by volume when the mixture was dried. Next, by applying this solution on a 200 mesh nylon net and drying it,
A positive electrode sheet having a size of 80 × 80 mm and a thickness of about 155 μm was obtained.

Next, the same electrolyte sheet and negative electrode sheet as used in preparing the battery C of Example 7 were prepared. Using these positive electrode sheet, electrolyte sheet, and negative electrode sheet, a battery C of this example was produced in the same manner as described above.

Next, for comparison, the battery D was prepared by the following method.
Was prepared. First, in acetonitrile in which 1 mol of LiBF4 was dissolved, electrolytic oxidation was performed at a potential of 1.0 V with respect to the potential of the Ag / AgCl electrode to obtain a disulfide compound containing no lithium ion. A battery C was prepared except that this was used in place of the conductive polymer containing a lithium thiolate group, and that a 200 μm thick lithium alloy plate having an aluminum content of 30 atomic% was used for the negative electrode. Battery D was produced in the same manner as in the above.

The batteries A and B thus prepared were
After applying a constant voltage of 3.6 volts to the batteries C and D at 65 ° C. for 17 hours, 1 μA, 10 μA,
Discharge was performed for 3 seconds at a current of 100 μA, 500 μA and 1 mA, respectively. The current-voltage characteristics were evaluated by recording the battery voltage. FIG. 9 shows the result. In the present example, comparing the current-voltage characteristics of the batteries A and C with the current-voltage characteristics of the batteries B and D of the comparative example, it can be seen that the former has a smaller voltage drop and a larger current can be obtained. .

[0100]

As described above, by using the electrode material of the present invention, it is not necessary to handle chemically active metallic lithium or its alloy at the time of assembling the battery, so that the battery assembling operation is safe. Further, in the lithium secondary battery assembled in this manner, no ignition occurs when the battery is destroyed.

Further, by using the battery of the present invention, a larger current can be taken out as compared with a conventional battery using lithium metal or its alloy as a negative electrode.

[Brief description of the drawings]

FIG. 1 is a current-voltage characteristic diagram of a reversible electrode using an electrode material according to a first embodiment of the present invention and a conventional electrode.

FIG. 2 is a current-voltage characteristic diagram of a battery using a reversible electrode using an electrode material according to a second embodiment of the present invention and a battery using a conventional electrode as a positive electrode.

FIG. 3 is a diagram showing current-voltage characteristics of a reversible electrode using an electrode material according to a third embodiment of the present invention and a conventional electrode.

FIG. 4 is a diagram showing current-voltage characteristics of a reversible electrode using the electrode material of a fourth embodiment of the present invention and a conventional electrode.

FIG. 5 is a current-voltage characteristic diagram of a reversible electrode using the electrode material according to a fifth embodiment of the present invention and a conventional electrode.

FIG. 6 is a diagram showing current-voltage characteristics of a reversible electrode using the electrode material according to a sixth embodiment of the present invention and a conventional electrode.

FIG. 7 is a diagram showing charge / discharge cycle characteristics of a reversible electrode using the electrode material according to the sixth embodiment of the present invention and a conventional electrode.

FIG. 8 is a diagram showing current-voltage characteristics of a lithium battery according to a seventh embodiment of the present invention and a conventional lithium battery.

FIG. 9 is a current-voltage characteristic diagram of a lithium battery according to an eighth embodiment of the present invention and a conventional lithium battery.

 ──────────────────────────────────────────────────続 き Continued on front page (31) Priority claim number Japanese Patent Application No. Hei 3-44734 (32) Priority date Hei 3 (1991) March 11 (33) Priority claim country Japan (JP) (31) Priority Claim No. Japanese Patent Application No. 3-137415 (32) Priority Date Hei 10 (1991) June 10 (33) Priority Claiming Country Japan (JP) (31) Priority Claim No. Japanese Patent Application No. 3-145856 (32) Priority Hihei 3 (1991) June 18, (33) Priority Country Japan (JP) (72) Inventor Yoshiko Sato 1006 Ojidoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Kenichi Takeyama No. 1006, Kadoma, Kadoma, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Noboru Koyama, No. 1006, Kadoma, Kadoma, Osaka Prefecture 1006 Matsushita Electric Industrial Co., Ltd.

Claims (8)

(57) [Claims] An electrode material comprising a combination of a compound having a disulfide group and a conductive polymer, or an electrode material having a conductive polymer having a disulfide group, wherein the SS bond of the disulfide group is cleaved by electrolytic reduction. An electrode material which forms a sulfur-metal ion bond or a sulfur-proton bond, wherein the sulfur-metal ion bond or the sulfur-proton bond forms an SS bond by electrolytic oxidation. 2. The electrode material according to claim 1, comprising a combination of a compound having a disulfide group and a conductive polymer, wherein the compound having a disulfide group has a cleavable disulfide group in the molecule. Electrode material. 3. The conductive polymer having a disulfide group,
2. The electrode material according to claim 1, wherein the electrode material is obtained by introducing a disulfide group into a π-electron conjugated conductive polymer. 4. The conductive polymer having a disulfide group,
2. The electrode material according to claim 1, wherein the electrode material is capable of forming a π-electron conjugated conductive polymer and is obtained by electrolytic polymerization of a monomer having a disulfide group. 5. A step of dimerizing a compound having a thiol group to obtain a dimer having a disulfide group, and a step of forming a monomer capable of forming a π-electron conjugated conductive polymer in the presence of the dimer. A method for producing a reversible electrode, comprising a step of performing electrolytic polymerization on an electrode substrate. 6. A positive electrode, a solid electrolyte, and a negative electrode, wherein the positive electrode mainly comprises a lithium thiolate having a sulfur-lithium ion bond capable of forming a disulfide bond by electrolytic oxidation and a π-electron conjugated conductive polymer. A composition containing a π-electron conjugated conductive polymer having a sulfur-lithium ion bond capable of forming a disulfide bond by electrolytic oxidation as a main component, wherein the solid electrolyte contains lithium. Or a lithium secondary battery, wherein the negative electrode is composed of a composition mainly composed of aluminum or an aluminum-containing alloy and carbon. battery. 7. The lithium secondary battery according to claim 6, wherein the electrolyte is mixed with a composition constituting a positive electrode or a composition constituting a negative electrode. 8. A polyether 3 obtained by adding at least one member selected from the group consisting of ethylene oxide and propylene oxide to a polyamine as a solid electrolyte.
And a lithium salt represented by LiX (where X is an anion of a strong acid), and a lithium secondary battery according to claim 6.