JP2001273901A - Electrode material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a battery of high energy density, provide an electrode material which is able to form an electrode superior in a reversibility, and in addition, provide a highly safe lithium battery using the electrode material. SOLUTION: The electrode material is used comprising characteristics that it has at least two disulphide moieties to form two thiolate groups which are cleaved in a molecule, and that it has a stereoscopic intramolecular configuration unable to take a configuration different from the stereoscopic intramolecular configuration concerning both sulfur atoms of the S-S bond before the cleavage when the S-S bond of the disulphide moieties is cleaved and a sulfur-metal ion bond or a sulfur-proton bond is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrode material for a battery having a disulfide group.

[0002]

2. Description of the Related Art A disulfide compound is disclosed in U.S. Pat.
No. 833,048. Japanese Patent No. 2715778 discloses an electrode material obtained by combining a compound having a disulfide group and a conductive polymer, or an electrode material made of a conductive polymer having a disulfide group, wherein the S- The S bond is cleaved by electrolytic reduction to form a sulfur-metal ion bond or a sulfur-proton bond, and the sulfur-metal ion bond or sulfur-proton bond is formed by electrolytic oxidation.
Electrode materials that form -S bonds are shown, and 1,8-disulfide naphthalene is illustrated. According to this technique, it is possible to solve the problems of the conventional disulfide compound such that a large current cannot be taken out because the potentials of oxidation and reduction are separated, and the cleavage and bonding of the SS bond of the disulfide group are prevented. Since it has a configuration that can occur reversibly in a molecule, reversibility is expected to be improved.

On the other hand, literature Gavrilov, AB; Kovalev, IP;
Skotheim, TAPhysical-Chemical and Electrochemical
Characterization of New Cathode Materials Based o
n Organo-Sulfur Polymers.Proc. 190 ^th ECS Meeting.vo
l.96-17,1996, p.204-212,
It is reported that a capacity of 1000 Wh / kg or more can be obtained by using ly (carbon disulfide) (PCS) as a positive electrode active material.

[0004]

SUMMARY OF THE INVENTION
The theoretical electrochemical capacity of 8-disulfide naphthalene is 28
As low as 2 mAh / g, it is insufficient for use as a battery electrode, and has a problem of lack of practicality. In addition, there has been a problem that 1,8-disulfide naphthalene alone is easily dissolved in an organic electrolyte, and it is difficult to use the lithium battery using the organic electrolyte.

On the other hand, the PCS is a polymer containing a large amount of sulfur atoms, and although it is expected to have a high capacity, it has a structure in which cleavage and bonding hardly occur reversibly in the molecule. In such a case, there is a problem that the capacity is greatly reduced due to the charge / discharge cycle. In addition, in the state where the PCS is cleaved, the solubility in the electrolytic solution is increased, so that when the PCS is used for a battery electrode, the electrode using the PCS dissolves, and problems such as performance degradation and short circuit are likely to occur. There was a problem.

[0006]

According to the present invention, as described in claim 1, there are provided two or more disulfide groups in a molecule which are cleaved to form two thiolate groups. When the SS bond of the disulfide group is cleaved,
When a metal ion bond or a sulfur-proton bond is formed, the intramolecular configuration relating to both sulfur atoms of the SS bond may take a different configuration from the intramolecular configuration relating to both sulfur atoms before the cleavage. An electrode material characterized by having no molecular structure.

[0007] The configuration in which the dissociation of the SS bond of the disulfide group can occur reversibly in the molecule means that the disulfide group forms a heterocyclic ring, and the disulfide group is further cleaved to form a sulfur-metal ion bond. However, it is a configuration in which, when cleaved, two sulfur atoms can always be present at the closest positions.

A more detailed description will be given using a model. For example, in the case of the compound having the structure shown on the left side of (Formula 1), when the compound is cleaved to form a sulfur-metal ion bond, the compound has a rotatable bond axis in the molecule between two benzene rings. It is possible to have a plurality of three-dimensional structures as shown in (A) and (B) shown on the right side of (Equation 1). However, when the three-dimensional structure shown in (B) is taken, it is difficult to form an SS bond again to cyclize and return to the original structure shown on the left side of (Equation 1). That is, the reversibility of cleavage-cyclization is poor.

[0009]

(Equation 1)

On the other hand, a compound having a structure as shown on the left side of (Formula 2) does not have an intramolecular rotation axis even when it is cleaved to form a sulfur-metal ion bond. It cannot have a three-dimensional structure other than the structure shown in. As a result, even in the cleavage state, two sulfur atoms can always be present at the closest positions. That is, the reversibility of the cleavage-cyclization is excellent.

[0011]

(Equation 2)

Also, the above-mentioned document Gavrilov, AB; Kovalle
v, IP; Skotheim, TAPhysical-Chemical and Electroc
chemical Characterization of New Cathode Materials
Based on Organo-Sulfur Polymers.Proc. 190 ^th ECS Mee
In ting. vol. 96-17, 1996, p. 204-212, the structural formulas of various organic sulfur polymer materials are described, but none of them has the disulfide group referred to in the present invention. The disulfide group referred to in the present invention refers to a sulfur-
When a metal ion bond or a sulfur-proton bond is formed, two groups each containing a sulfur atom constituting the above-mentioned SS bond are both thiolate groups.

An explanation will be given by giving an example. The left side of (Equation 3) is
It is an example of the organic sulfur polymer material described in the literature. Assuming that the SS bond of this material has been cleaved to form a sulfur-metal ion bond, as shown on the right side of (Equation 3), 2 containing each sulfur atom constituting the SS bond One group is divided into a thiolate group and a thiocarbonate group. Therefore, the organic sulfur polymer materials described in the above documents are excluded from the scope of the present invention. Thus, when one forms a thiocarbonate group, the double bond of the thiocarbonate group is delocalized between one carbon atom and two sulfur atoms. When such delocalization occurs, as compared with the case where the delocalization does not occur as in the electrode material of the present invention, the cyclization is less likely to occur, and the potential difference between oxidation and reduction increases. It is expected that a problem for the electrode reaction will occur.

[0014]

(Equation 3)

When an electrode using the electrode material of the present invention is subjected to electrolytic reduction in the presence of, for example, lithium ions, the SS bond of the disulfide group of the electrode material is cleaved to form a sulfur-lithium bond. You. When this is electrolytically oxidized again, it cyclizes and returns to the original SS bond. This cleavage-cyclization reaction corresponds to a charge / discharge reaction in the battery. By utilizing this, it can be used as a positive electrode active material or a negative electrode active material of a battery.

For the above-mentioned reasons, in the battery using the electrode material of the present invention, the intramolecular cyclization by oxidation easily proceeds even after ring opening, so that the reversibility of the electrode reaction can be improved.

Furthermore, by having two or more cleavable disulfide groups in the same molecule, it is possible to increase the capacity.

For the electrode material of the present invention, specific examples of compound names include naphtho [1,8-cd: 4,5-c'd '] bis [1,
2] dithiol (tetrathionaphthalene), 2,3-dimethylnaphtho [1,8-cd: 4,5-c'd '] bis [1,2] dithiol, 2,3,
6,7-tetramethylnaphtho [1,8-cd: 4,5-c'd '] bis [1,2]
Dithiol, naphthacene [5,6-cd: 11,12-c'd '] bis [1,
2] dithiol (tetrathiotetracene), anthra [1,1
0-cd: 4,5-c'd '] bis [1,2] dithiol (tetrathioanthracene), 2,3-dimethylanthra [1,9-cd: 4,10-c'd']
Bis [1,2] dithiol, 2,3,7,8-tetramethylanthra
[1,10-cd: 4,5-c'd '] bis [1,2] dithiol, phenanthro [1,10-cd: 8,9-c'd'] bis [1,2] dithiol, etc. No.

The present invention also provides an electrode material using naphtho [1,8-cd: 4,5-c'd '] bis [1,2] dithiol, as described in claim 2. is there.

Among the compounds listed above, naphtho [1,8-cd: 4,5-c'd '] bis [1,2] dithiol has an electrochemical capacity as high as 425 mAh / g. Is about 1.5 times the value of 1,8-disulfide naphthalene. Furthermore, since sulfur is directly bonded to the rigid planar molecular skeleton, in the state where the ring is opened to form a sulfur-lithium bond,
The two sulfur atoms are always located close to each other and can easily return to the original sulfur-sulfur bond when electrolytic oxidation is performed again, thereby improving the cycle characteristics. Naft [1,8-c
The molecular structural formula of d: 4,5-c'd '] bis [1,2] dithiol is shown in (Formula 4).

[0021]

(Equation 4)

Further, naphtho [1,8-cd: 4,5-c'd '] bis
[1,2] dithiol is preferable because it has a lower solubility in an organic electrolyte than 1,8-disulfide naphthalene, and the electrode material is less likely to elute into the electrolyte. Therefore, the electrode material of the present invention can be used alone, and Japanese Patent 27
As described in US Pat. No. 15,778, there is no need to use in combination with a conductive polymer.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is not limited by the following description.

When the electrode material of the present invention is used as a positive electrode active material, a material generally used for a negative electrode for a lithium battery can be used as a negative electrode active material. For example, lithium-containing alloys such as lithium metal, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and wood alloys, and the following carbon materials may be mentioned. For example, 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.
Particles or fibers having a fiber length of from 10 μm to 10 μm and a fiber length of from several μm to several mm are preferred. In particular, the above carbon material is analyzed by X-ray diffraction or the like; Lattice spacing (d ₀₀₂ ) 0.333 to 0.350 nm Size of crystallite in a-axis direction La 20 nm or more Size of crystallite in c-axis direction Lc 20 nm or more True density; 2.00 to 2.25 g / cm ³ of graphite is preferable because of high capacity. However, it is not limited to these ranges.

Further, the carbon material may be modified by adding a metal oxide such as tin oxide or silicon oxide, or by adding phosphorus or boron. Also, by using graphite in combination with lithium metal, lithium-containing alloy, etc., or by electrochemical reduction in advance,
It is also possible to insert lithium in advance into the carbonaceous material used in the present invention.

When the electrode material of the present invention is used as a negative electrode active material, a material generally used for a positive electrode for a lithium battery can be used as a positive electrode active material. For example, materials such as lithium-containing transition metal oxides and phosphates that exhibit a discharge voltage of 3 V or more with respect to lithium are preferably used.
In particular, a material that can obtain a discharge potential of 4 V or more is more preferable because a high battery voltage can be obtained and the energy density is improved. As the lithium-containing transition metal oxide, for example,
General formulas Li _y Co _1-x M _x O ₂ , Li _y Mn _2-x M _X O ₄ ｛M
Are metals of groups I to VIII (eg, Li, Ca, Cr,
One or more elements such as Ni, Fe, and Co), and the x value indicating the replacement amount of the different element is effective up to the maximum amount that can be replaced, but preferably 0 ≦ x ≦ 1 from the viewpoint of discharge capacity.
It is. As the y value indicating the amount of lithium, a maximum amount capable of reversibly using lithium is effective, but preferably 0 <y ≦ 2 from the viewpoint of discharge capacity. ｝, But is not limited thereto.

The lithium-containing transition metal oxide is
Other active materials can be further mixed and used. example
For example, CuO, Cu_TwoO, Ag_TwoO, CuS, CuSO_Four
Group I metal compounds such as TiS_Two , SiO_Two, SnO
Which group IV metal compound, V_Two O _Five , V₆ O₁₂, VO_x, N
b_TwoO_Five , Bi_TwoO_Three , Sb_TwoO_ThreeGroup V metal compounds such as
Object, CrO_Three , Cr_TwoO_Three, MoO_Three , MoS_Two, WO_Three
 , SeO_TwoGroup VI metal compounds such as MnO_Two, Mn_TwoO_Three
Group VII metal compounds such as Fe_TwoO_Three, FeO, Fe_ThreeO_Four
 , FePO_Four, Ni_TwoO_Three, NiO, CoO_Three, CoO
Any group VIII metal compound and the like can be mentioned. In addition, disul
Fido, polypyrrole, polyaniline, polyparaphenyl
Conductivity of materials such as len, polyacetylene, and polyacene
Using polymer compound, pseudo-graphite structure carbonaceous material, etc.
However, the present invention is not limited to these.

The method for forming the electrode material of the present invention includes, for example, roller coating such as an applicator roll, screen coating, a doctor blade method,
It is desirable to apply it to the current collector with an arbitrary thickness and an arbitrary shape by using a means such as spin coating or a bar coder, but it is not limited thereto.
When these means are used, it is possible to increase the actual surface area of the electrochemically active substance that comes into contact with the electrolyte layer and the current collector.

In the electrode material of the present invention, a conductive agent, a binder, a filler and the like can be added to the electrode mixture as needed.

The conductive agent may be any electronic conductive material that does not adversely affect battery performance. Normal,
Natural graphite (flaky graphite, flaky graphite, earthy graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon whisker, carbon fiber and metal (copper, nickel, aluminum, silver, gold, etc.) powder, A conductive material such as a metal fiber, a conductive ceramic material, or a conductive polymer can be included as one type or a mixture thereof. Among these, acetylene black is desirable from the viewpoint of conductivity and coatability. The addition amount is 1 to 50
% By weight, particularly preferably 2 to 30% by weight. These mixing methods are physical mixing, and ideally, uniform mixing. Therefore, V-type mixer, S
A powder mixer such as a mold mixer, a grinder, a ball mill, and a planetary ball mill can be mixed in a dry or wet manner.

Examples of the binder include tetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluoro rubber, and carboxymethyl cellulose. And the like, a thermoplastic resin, a polymer having rubber elasticity, a polysaccharide and the like can be used as one kind or as a mixture of two or more kinds. Further, it is desirable that a binder having a functional group that reacts with lithium, such as a polysaccharide, be deactivated by, for example, methylation.
The addition amount is preferably 1 to 50% by weight, particularly preferably 2 to 30% by weight.

The filler may be any material as long as it does not adversely affect battery performance. Usually, olefin polymers such as polypropylene and polyethylene, aerosil, zeolite, glass, carbon and the like are used. The addition amount of the filler is preferably 0 to 30% by weight.

It is also possible to add chalcogen elements such as sulfur, selenium and tellurium to the electrode material of the present invention. The chalcogen element is added to the SS bond of the disulfide group of the electrode material, and the electrochemical capacity is further increased. The addition amount of the chalcogen element is preferably 30% by weight or less based on the electrode material of the present invention.

As the positive electrode current collector and the negative electrode current collector, any electronic conductor may be used as long as it does not adversely affect the constructed battery. For example, as the positive electrode current collector, aluminum, titanium, stainless steel, nickel, calcined carbon,
In addition to conductive polymers, conductive glass, etc., adhesion, conductivity,
For the purpose of improving oxidation resistance, a material obtained by treating the surface of aluminum, copper, or the like with carbon, nickel, titanium, silver, or the like can be used. As the negative electrode current collector, copper, nickel,
Iron, stainless steel, titanium, aluminum, calcined carbon,
In addition to conductive polymers, conductive glasses, Al-Cd alloys, etc., for the purpose of improving adhesiveness, conductivity, and oxidation resistance, copper and other surfaces treated with carbon, nickel, titanium, silver, etc. Can be used. These materials can be oxidized on the surface. As these shapes, in addition to the foil shape, a film shape, a sheet shape, a net shape, a punched or expanded material, a lath body, a porous body, a foamed body, a formed body of a fiber group, and the like are used. The thickness is not particularly limited, but a thickness of 1 to 500 μm is used.
Among these current collectors, the positive electrode is an aluminum foil having excellent oxidation resistance, and the negative electrode is stable in a reduction field, and has excellent electrical conductivity, and is inexpensive copper foil, nickel foil, iron foil, And alloy foils containing some of them. Further, it is desirable that the foil having a rough surface roughness of 0.2 μmRa or more, which has excellent adhesion between the electrochemically active material layer and the current collector, is used. Electrolytic foils are excellent for obtaining such a rough surface.

A metal can made of iron, stainless steel, aluminum or the like can be used as an outer package of a battery using the electrode material of the present invention. From the viewpoint of weight energy density, a metal foil and a resin film are used. A laminated metal resin composite film is preferred. Examples of metal foils include aluminum, iron, nickel, copper, SUS, titanium, gold, silver, etc.
Any foil may be used as long as it has no pinhole, but a lightweight and inexpensive aluminum foil is preferred. Further, a resin film having excellent piercing strength such as a polyethylene terephthalate film or a nylon film on the outer surface, and a resin film having a thermoplastic and fusible film such as a polyethylene film or a nylon film on the inner surface is also preferably used. . From the viewpoint of solvent resistance, the opening of such a resin film is desirably sealed with a thermoplastic resin.

As a separator of a battery using the electrode material of the present invention, a microporous membrane or nonwoven fabric of a polyolefin, polyester, polyacrylonitrile, polyphenylene sulfide, polyimide, or fluororesin type can be used. . Among them, it is preferable to treat the microporous membrane having poor wettability with a surfactant or the like.

The porosity of the separator is preferably 98% by volume or less from the viewpoint of strength. Further, the porosity is preferably 20% by volume or more from the viewpoint of charge and discharge characteristics.

In the battery using the electrode material of the present invention,
As the ionic compound used for the decomposition, for example, LiC
10_Four, LiBF_Four, LiAsF₆, LiPF₆, LiC
F_ThreeSO_Three, LiCF_ThreeCO_Two, LiSCN, LiBr, L
iI, Li_TwoSO_Four, Li_TwoB_TenCl_Ten, NaClO_Four, N
aI, NaSCN, NaBr, KClO_Four, KSCN,
Inorganic ion containing one kind of Li, Na or K such as
Salt, LiN (CF_ThreeSO_Two) _Two, LiN (C_TwoF_FiveS
O_Two)_Two, (CH_Three)_FourNBF_Four, (CH_Three)_FourNBr, (C
_TwoH_Five)_FourNCLO_Four, (C_Two H_Five)_Four NI, (C_Three H₇)_Four
NBr, (n-C_FourH₉)_FourNCLO_Four, (N-C_FourH₉)_Four
NI, (C_Two H_Five)_FourN-maleate, (C_TwoH_Five)_Four
N-benzoate, (C_TwoH_Five)_FourN-phtala
quaternary ammonium salts such as te, stearyl sulfonic acid
Lithium, lithium octyl sulfonate, dodecylben
Examples include organic ionic salts such as lithium zensulfonate
It is.

The ionic compound can be used by dissolving it in an organic solvent or the like. Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, chloroethylene carbonate, and vinylene carbonate; cyclic esters such as γ-butyrolactone and γ-valerolactone; dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. Chain esters such as methyl acetate and methyl butyrate; ethers such as tetrahydrofuran or derivatives thereof, 1,3-dioxane, 1,2-dimethoxyethane and methyldiglyme; nitriles such as acetonitrile and benzonitrile It is also possible to add dioxane or its derivative; sulfolane, sultone or its derivative alone or a mixture of two or more thereof. However, it is not limited to these. By adding such an organic solvent, battery characteristics such as cycle characteristics and stability can be improved.

The above-mentioned electrolytic solution may be injected after the separator of the present invention is sandwiched between the electrodes and laminated or rolled up. As the liquid injection method, it is possible to inject liquid at normal pressure, but a vacuum impregnation method or a pressure impregnation method may be used.

As an electrolyte for a battery using the electrode material of the present invention, a solid lithium ion conductive solid electrolyte at a temperature of -20 to 60 ° C. can be used. The solid electrolyte is a polyethylene oxide derivative obtained by dissolving the ionic compound or a polymer containing at least the derivative, a polypropylene oxide derivative or a polymer containing at least the derivative, polyphosphazene or the derivative, a polymer containing an ion dissociating group, Phosphoric acid ester polymer derivatives, polyvinyl pyridine derivatives, bisphenol A derivatives, polyacrylonitrile, polyvinylidene fluoride, polymer matrix materials (gel electrolytes) containing a non-aqueous electrolyte in fluororubber, etc., and inorganic solid electrolytes What consists of an ion conductive compound can be used.

[0042]

EXAMPLES (Synthesis of Naphtho [1,8-cd: 4,5-c'd '] bis [1,2] dithiol (TTN)) Naphtho [1,8-cd: 4,5-c'd '] Screw [1,2]
Dithiol (hereinafter referred to as "TTN") was synthesized in four steps using 1,5-naphthalenediamine as a starting material.

First step: 1,5-bistosylaminonaphthale
Synthesis of 1,2- naphthalenediamine (23 g, 150 mmol) in pyridine (240 ml)
And added with 62.91 g (330 mmol) of tosyl chloride,
And stirred under reflux. After confirming complete dissolution,
After refluxing for 30 minutes, the mixture was allowed to cool, and the reaction was stopped by adding 2 ml of concentrated sulfuric acid and water, followed by filtration. The collected material was washed with water, ethanol and chloroform in this order to obtain 1,5-bistosylaminonaphthalene (2NHTs-NP).

Second stage: 1,5-dibromo-4,8-bis (toshi
Synthesis of l-amino ) naphthalene (2Br-2NHTs-NP) 1,5 -bistosylaminonaphthalene (2NHTs-NP) 46.66
g (100 mmol) was added to 400 ml of acetic acid and stirred at 70-80 ° C.
Further, a mixed solution of 11.2 ml (110 mmol) of bromine and 180 ml of acetic acid was slowly dropped, and the mixture was stirred for 30 minutes after the drop. After standing to cool, the reaction was stopped with water, filtered, and the collected matter was filtered with water, ethanol,
Washing was performed in the order of chloroform. Further, the collected matter was washed with hot chloroform, and the filtrate was concentrated and washed with chloroform to obtain 1,5-dibromo-4,8-bis (tosylamino) naphthalene (2Br-2NHTs-NP).

Third stage: 1,5-dibromo-4,8-diiodona
Synthesis of phthalene (2Br-2I-NP) 15.6 g (25 mmol) of 1,5-dibromo-4,8-bis (tosylamino) naphthalene (2Br-2NHTs-NP) was dissolved in 60 ml of concentrated sulfuric acid, and the solution was dissolved in a salt ice bath. 5.87 g sodium nitrite while cooling
(85 mmol) in 20 ml of water was slowly added dropwise. After stirring until the gas disappears, potassium iodide 2.
An aqueous solution in which 4 g (150 mmol) was dissolved in 20 ml of water was slowly dropped. After stirring for 1 hour as it is,
Stirred for hours. Next, after heating at 70 ° C for 30 minutes, let it cool down,
Cooled in a salt ice bath. The reaction was slowly stopped with an aqueous solution in which 100 g of sodium hydroxide was dissolved, extracted with chloroform, and filtered with celite. After liquid separation, the aqueous layer was separated twice with chloroform, and the oil layer was washed with a 10% aqueous sodium hydroxide solution, 5% hydrochloric acid, a saturated aqueous solution of sodium bicarbonate, and a saturated aqueous solution of sodium chloride in that order.
It was dried over sodium sulfate and distilled under reduced pressure. Silica gel column chromatography (Hexane)
It was obtained as a mixture of 1,5-dibromo-4,8-diiodonaphthalene (2Br-2I-NP) and impurities at a ratio of 2: 1.

Step 4: Naphtho [1,8-cd: 4,5-c'd '] bis
Synthesis of [1,2] dithiol (TTN) Under an argon atmosphere, 0.36 g (15.84 mmo ) of solid sodium
15 ml of dry toluene was poured into l), and the mixture was refluxed and stirred at 120 ° C. until the mixture became fine granules. The mixture was allowed to cool to room temperature with vigorous stirring, toluene was removed, washed with pentane two to three times, and pentane was removed under reduced pressure. Inject 15 ml of dry dimethylformaldehyde (DMF) and add 0.47 g (14.4 ml) of sulfur
Was added and stirred at 100 ° C. until a yellow solution was obtained. 1,5
1.3 g of a mixture of -dibromo-4,8-diiodonaphthalene (2Br-2I-NP) and impurities at a ratio of 2: 1 and dry dimethylformaldehyde (DMF) (25 ml) were injected, and the mixture was stirred for 18 hours. After cooling, the reaction was stopped with water and 10% hydrochloric acid, extracted with chloroform, filtered through celite, and washed with hot chloroform. The filtrate was washed sequentially with 10% hydrochloric acid, an aqueous solution of sodium hydrogen carbonate and saturated saline, dried over sodium sulfate and distilled under reduced pressure. The target product was isolated by silica gel column chromatography (Hexane), and recrystallized from chloroform to obtain naphtho [1,8-cd: 4,5-c'd '] bis [1,2] dithiol (TTN). .

(Preparation of TTN Electrode) Naphtho [1,8-cd: 4,5-c'd '] bis [1,2] dithiol (TTN) 34 m
g and 10 mg of acetylene black were kneaded in an agate mortar, 283 mg of an N-methylpyrrolidone solution in which 12% by weight of polyvinylidene fluoride was dissolved, and further kneaded. Next, about 2 ml of N-methylpyrrolidone was added to form a paste. The paste-like substance was applied on an aluminum foil and heated to about 80 ° C. to remove N-methylpyrrolidone, thereby obtaining a TTN electrode.

(Preparation of Electrolyte / Separator) As the electrolyte / separator 3, an ion conductive compound supported on a nonwoven fabric was used. The manufacturing method of the electrolyte / separator 3 is as follows. That is, in order to support the ion conductive compound layer on a polyethylene nonwoven fabric, 10% by weight of acrylate-modified polyethylene glycol, 6% by weight of lithium tetrafluoroborate, and 30% by weight of ethylene carbonate
Was cast on both surfaces of the nonwoven fabric, and cured by irradiating an electron beam with an electron dose of 80 kGy in an inert gas atmosphere to obtain an electrolyte / separator 3. The thickness of the electrolyte / separator 3 thus obtained was 30 μm.

(Battery 1 of the Invention) A negative electrode 4 was obtained by pressing lithium on a nickel plate. The positive electrode 2 was used as the TTN electrode. The negative electrode 4 and the positive electrode 2 have terminals 7, 7 respectively.
Was attached. The negative electrode 4 and the electrolyte / separator 3
Then, the positive electrode 2 was laminated in this order, and the battery 1 of the present invention was produced using a metal resin composite film as the exterior material 6. FIG. 1 shows a perspective plan view and FIG. 2 shows a cross-sectional view of the battery 1 of the present invention.

The obtained Battery 1 of the present invention was subjected to cyclic voltammetry (CV) measurement. The upper and lower limits of the scanning potential were set to +1.5 to +3.5 V, and five cycles of linear scanning were performed at a speed of 10 mV / sec. Figure 3 shows the measurement results.
Shown in

The battery 1 of the present invention was subjected to a constant current discharge at a current of 0.1 mA and a cut-off voltage of 1.5 V.
A, constant-current charging with a final voltage of 3.5 V was performed. As a result, the charge / discharge characteristics shown in FIG. 4 were obtained.

(Battery 2 of the Invention) The TTN electrode was connected to the negative electrode 4
Next, a lithium secondary battery using lithium cobalt oxide as the lithium-containing transition metal oxide for the positive electrode 2 was produced.

After 34 mg of lithium cobaltate and 34 mg of acetylene black were kneaded in an agate mortar, 283 mg of an N-methylpyrrolidone solution in which 12% by weight of polyfukkavinylidene was dissolved was added and kneaded. Next, N
-About 2 ml of methylpyrrolidone was added to form a paste. The obtained paste-like substance was applied on an aluminum foil, and heated at about 80 ° C. to remove N-methylpyrrolidone, whereby a positive electrode 2 was obtained. On the other hand, the TTN electrode was used for the negative electrode 4. The battery 2 of the present invention was assembled in the same manner as the battery 1 of the present invention.

The obtained battery 2 of the present invention was supplied with a current of 0.1
After performing constant-current charging at a current of mA and a final voltage of 2.5 V, constant-current discharging at a current of 0.1 mA and a final voltage of 0.5 V was performed.
FIG. 7 shows a charge / discharge curve at the fifth cycle.

(Comparative Battery) A comparative battery was prepared in the same manner as in Example 1 except that 1,8-disulfide naphthalene (hereinafter referred to as "DTNP") was used as the electrode material instead of TTN. Cyclic voltammetry measurement was performed under the same conditions as in Example 1. FIG. 5 shows the results. A charge / discharge test was performed under the same conditions as in Example 1. As a result, the charge / discharge characteristics shown in FIG. 6 were obtained. Here, the charge curve is so small that it overlaps with the discharge curve in the figure and cannot be discriminated.

When the results of cyclic voltammetry of the battery 1 of the present invention and the comparative battery were compared, peaks of oxidation and reduction were obtained at similar potentials, but TTN, which is the electrode material of the present invention, showed reversibility. It turns out that it is excellent. This is presumably because TTN has lower solubility in the electrolytic solution than DTNP and has improved reversibility.

The results of the charge / discharge test show that the battery 1 of the present invention using TTN has a large discharge capacity and a large charge capacity. On the other hand, in the comparative battery using DTNP,
Charging was almost impossible. This is considered to be because almost all of DTNP, which is an electrode material, was eluted into the electrolytic solution by the discharge. Further, the magnitude of the charge / discharge capacity reflects the fact that the electrode material of the present invention has two disulfide groups in the molecule, and it is understood that the electrode material is excellent as an electrode material.

As is clear from FIG. 7, the electrode material of the present invention can be used as a negative electrode active material.
That is, a lithium secondary battery that does not use lithium metal can be manufactured. It is preferable to use a material having an average potential of about 5 V with respect to the lithium potential as the positive electrode active material because a higher battery voltage can be obtained.

[0059]

As described above, by using the electrode material of the present invention, an electrode having a high capacity and excellent cycle characteristics can be obtained. If the electrode of the present invention is used for the negative electrode and a lithium-containing transition metal oxide is used for the positive electrode, it is not necessary to handle chemically active lithium metal or an alloy thereof at the time of battery assembly, so that the battery assembly operation is safe. Further, in the lithium secondary battery assembled in this manner, there is no fear that the battery will be ignited when the battery is destroyed.

[Brief description of the drawings]

FIG. 1 is a perspective plan view of a battery of the present invention.

FIG. 2 is a cross-sectional view of a portion A of the battery of the present invention.

FIG. 3 is a current-voltage characteristic diagram of the battery 1 of the present invention.

FIG. 4 is a charge / discharge characteristic diagram of the battery 1 of the present invention.

FIG. 5 is a current-voltage characteristic diagram of a comparative battery.

FIG. 6 is a charge / discharge characteristic diagram of a comparative battery.

FIG. 7 is a charge / discharge characteristic diagram of the battery 2 of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 positive electrode current collector 2 positive electrode 3 electrolyte / separator 4 negative electrode 5 negative electrode current collector 6 exterior material 7 terminal

Claims (2)

[Claims] 1. A molecule having two or more disulfide groups which are cleaved to form two thiolate groups in a molecule, and wherein an SS bond of the disulfide group is cleaved to form a sulfur-metal ion bond or sulfur- Having a molecular structure in which the intramolecular configuration of both sulfur atoms of the SS bond when forming a proton bond cannot take a different configuration from the intramolecular configuration of both sulfur atoms before the cleavage. An electrode material characterized by the following: 2. An electrode material having naphtho [1,8-cd: 4,5-c'd '] bis [1,2] dithiol.