JPH0896817A - Battery using ion conductive high polymer compound - Google Patents

Abstract

PURPOSE: To manufacture a battery with high workability in a production process and high performance by constituting an ion conductive polymer compound used as a material of a composite positive electrode, an electrolyte, and a composite negative electrode with an organic compound represented by a specific formula. CONSTITUTION: In a battery comprising a composite positive electrode having an ion conductive polymer compound containing at least one kind of an ion compound [such as LiN(SO2 CF3 )2 ] as a constituting material, an electrolyte made of the ion conductive polymer compound, and a composite negative electrode having the ion conductive polymer compound as a constituting material or a negative electrode using an alkali metal as a main component, the ion conductive polymer compound is constituted with at least one of organic compounds represented by formulas I, II, and III. (R1 -R8 represent hydrogen atom or lower alkyl group having at least one carbon atom, m>=1, n>=0, n/m is 0-5, k>=3, 1>=0, 1/k is 0-5, p1 , p2 , p3 are equal to or larger than 3, q1 , q2 , q3 are equal to or larger than 0, q1 /p1 , q2 /p3 , q3 /p3 are 0-5, p1 +q1 , p2 +q2 , p3 +q3 are equal to or larger than 10).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery using an ion-conducting polymer compound that operates reversibly at ambient temperature, and relates to improvement of electrolyte, positive electrode and negative electrode.

[0002]

2. Description of the Related Art Recently, as microelectronics has been used, as represented by a power source for memory backup of various electronic devices, a battery has been miniaturized in accordance with the storage of the battery in the electronic device and the integration with electronic elements and circuits. There is a demand for batteries that are lighter in weight, thinner, and have a higher energy density. Therefore, as a battery replacing the conventional lead battery and nickel-cadmium battery, a primary battery and a secondary battery using a non-aqueous electrolyte that can be made smaller and lighter have attracted attention, but the cycle characteristics of the electrode active material, Many research institutions are currently studying it in order to further improve the practical physical properties such as self-discharge characteristics.

In such a flow, the present inventors have
In designing batteries that are smaller, lighter, have higher energy density, and have higher reliability, the following problems are separately examined. 1) Problems of Electrode Active Material and Electrode 2) Problems of Electrolyte The present invention has been found as a result of mainly considering the above-mentioned improvement in 2).

The above problem 2) is as follows. That is, as an electrolyte for a battery or an electrochemical device other than a battery that has conventionally used an electrochemical reaction, that is, an electric double layer capacitor, an electrochromic element, etc., a ionic compound is generally dissolved in a liquid electrolyte, particularly an organic electrolyte. Although liquid electrolytes have been used, liquid electrolytes are prone to liquid leakage to the outside of parts, elution of electrode substances, volatilization, etc., so problems such as long-term reliability and scattering of electrolytes in the sealing process, etc. Was a problem.

Therefore, in order to improve the liquid leakage resistance and the long-term storage stability, an ion conductive polymer compound having high ion conductivity has been reported, and further research is being conducted as one of the means for solving the above problems. It is being advanced.

The ion-conducting polymer compounds currently being studied are homopolymer or copolymer linear polymers having ethylene oxide as a basic unit, reticulated cross-linked polymers, comb polymers, etc. For the purpose of increasing the ionic conductivity of the polymer, it has been proposed and practiced to prevent the crystallization by using a crosslinked polymer or a comb polymer. In particular, the ion-conductive polymer compound using the above-mentioned network cross-linked polymer is useful because it has high mechanical strength and good ionic conductivity at low temperatures. Electrochemical cells using the above ion-conductive polymer compounds have been widely described in patent documents and the like, for example, US Pat. No. 4,303,748 (1981) by Armand et al.
And North US Pat. No. 4,589,197 (1986) and Hooper et al. US Pat. No. 4,547,440 (198).
5) etc. One of the characteristics of these cells is that an ion-conductive polymer compound obtained by dissolving an ionic compound in a polymer material having a polyether structure is used.

However, in order to use the above-mentioned ion-conductive polymer compound as an electrolyte for batteries using electrochemical reaction or electrochemical devices other than batteries, high ion conductivity and good mechanical properties (mechanical strength) are used. , And flexibility), but these two characteristics are in conflict. That is, in most of the above-mentioned patent documents, since the ionic conductivity at room temperature or lower is below the practical range, it is the current situation to operate mainly at a raised temperature.

Then, as a simple method for improving the ionic conductivity, for example, JP-A-59-149601 and JP-A-58-7.
There has been proposed a method of maintaining a solid state by adding an organic solvent (particularly preferably a high dielectric constant organic solvent) to an ion conductive polymer compound, as represented by 5779 and US Pat. No. 4,792,504. However, as a result, the ionic conductivity is certainly improved, but the film strength is significantly reduced. From these facts, in the above-mentioned ion conductive polymer compound, it is important to improve its ion conductivity and mechanical properties.

On the other hand, with respect to the ionic compound used as the ion conductive polymer compound, for example, in the case of Li salt, the following points are problems. That is, a) LiAsF ₆ contains a problem of arsenic and is problematic in terms of environmental protection. b) LiClO ₄ has a problem in over-discharge when used as a battery and in safety after reversal. c) LiCF ₃ SO ₃ has a large problem in terms of polarization characteristics due to ionic conductivity and solubility. d) LiPF ₆ has a problem of generation of hydrogen fluoride when it is stored at high temperature for a long period of time, so it is necessary to improve the high temperature storability. And so on.

Further, in the sheet type battery using the above-mentioned ion-conductive polymer compound, when manganese dioxide is used as the electrode active material of the composite positive electrode, the conventional manganese dioxide-
Similar to the case of the non-aqueous electrolyte battery, problems such as expansion of the battery may occur. That is, when the battery is left as it is after the sheet-shaped battery is manufactured, gas is generated inside the battery to cause an accident such as expansion and rupture, or a problem such as a decrease in battery performance due to an increase in internal resistance of the battery occurs. It was

Further, when the ion conductive polymer compound is used, it is necessary to pay attention to the following problems. i) When using a Li salt other than the above-mentioned LiClO ₄ , the ionic conductivity may fall below the practical range. (Especially in room temperature or below, for example, in the temperature range of 0 ° C. to −20 ° C.) ii) When a Li salt such as LiPF ₆ or LiBF ₄ is used, there is a problem of stability of the Li salt in the ion conductive polymer compound. is there. (In particular, as a method of forming the composite positive electrode, the electrolyte, and the composite negative electrode described above, the problem of stability of Li salt when irradiating with actinic radiation such as ionizing radiation, and the problem of thermal stability) In the battery using the ion conductive polymer compound which the present inventors are studying, it is necessary to select an optimal electrolyte having all of the environmental aspect, the characteristic aspect, and the safety.

From such a way of thinking, Japanese Patent Laid-Open No. 58-
As shown in No. 225045, for example, an ionic compound composed of lithium bis (trifluoromethylsulfonyl) imide or lithium bis (trifluoromethylacetyl) imide has been proposed. These ionic compounds were extremely effective means for solving the above problems a) to d), but had the following problems.

It is the presence of impurities such as NH ₂ SO ₂ CF ₃ , NH ₂ COCF ₃ and NH ₄ SO ₂ CF ₃ contained in the above ionic compounds. These impurities are synthesized as by-products when using the synthesis method of JP-A-58-225045.

For example, when NH ₂ SO ₂ CF ₃ or the like is present in the ion conductive polymer compound, the following problems occur. i) When an alkali metal such as lithium is used for the negative electrode,
NH ₂ SO ₂ CF ₃ reacts with lithium to generate H ₂ gas and the like. ii) When a carbonaceous material is used for the negative electrode and LiCoO ₂ , LiNiO ₂ or the like is used for the positive electrode, NH ₂ SO ₂ CF ₃ reacts with the above electrode active material to form a passive film on the surface of the electrode active material. Cause
This caused a phenomenon such as a significant decrease in battery performance. iii) When forming the above composite positive electrode, composite negative electrode, or electrolyte by irradiation with actinic radiation such as ionizing radiation, NH ₂ S
O ₂ CF ₃ reacts with a polymerizable monomer that forms an ion conductive polymer compound, and as in i) and ii), a passive film is formed on the surface of the electrode active material and H ₂ gas is generated.

Therefore, when the above-mentioned ionic compound such as lithium bis (trifluoromethylsulfonyl) imide is applied to the battery using the ion-conductive polymer compound which the present inventors are investigating, the above-mentioned ionic compound is used. It was necessary to reduce the amount of impurities.

[0016]

DISCLOSURE OF THE INVENTION The present invention provides a small and lightweight battery using an ion-conductive polymer compound, which is extremely superior to conventional batteries in the following points. That is, 1) There is no concern about leakage of liquid to the outside and long-term reliability and safety are high. In particular, the present invention achieves the above object by suppressing gas generation inside the battery. 2) High performance and high energy density. In particular, the present invention achieves the above object by improving the ion conductivity and mechanical properties of the ion-conductive polymer compound and suppressing the formation of a passive film. 3) It has very high workability. The above object is achieved by effectively using a method of crosslinking an ion-conductive polymer compound by irradiation with ionizing radiation.

[0017]

In order to achieve the above object, the present invention provides a composite positive electrode having as a constituent material an ion-conducting polymer compound containing at least one ionic compound in a dissolved state. A battery comprising an electrolyte composed of the ion conductive polymer compound and a composite negative electrode having the ion conductive polymer compound as a constituent material or a negative electrode mainly composed of an alkali metal, wherein the ion conductive polymer The compound is composed of at least one of the following, and: at least an organic compound represented by the following chemical formula 1 or / and the following chemical formula 2 or / and the following chemical formula 3.

[0018]

[Chemical 1] (R ₁ , R ₂ and R ₃ are hydrogen or a lower alkyl group having 1 or more carbon atoms, m and n are numbers m ≧ 1, n ≧ 0 and n / m = 0 to 5)

[0019]

[Chemical 2] (R ₄ , R ₅ , and R ₆ are hydrogen atoms or lower alkyl groups having 1 or more carbon atoms, k and l are k ≧ 3, l ≧ 0, and 1 / k =
Indicates a number in the range 0 to 5. )

[0020]

[Chemical 3] (R ₇ and R ₈ are hydrogen or a lower alkyl group having 1 or more carbon atoms, and p ₁ , p ₂ , p ₃ , q ₁ , q ₂ and q ₃ are p ₁ ≧ 3, p ₂ ≧ 3 and p _{3 respectively.} ≧ 3, q ₁ ≧ 0, q ₂ ≧
0, q ₃ ≧ 0, q ₁ / p ₁ = number in the range of 0 to 5, q ₂ /
p ₂ = 0-5, q ₃ / p ₃ = 0-5, and p ₁ + q ₁ ≧ 10, p ₂ + q ₂ ≧ 10,
It shows that p ₃ + q ₃ ≧ 10. ): An ionic compound having the formula shown below

[0021]

Embedded image M ⁺ -N (Y—C _n X _{2n + 1} ) ₂ (M is an alkali metal element such as Li or Na, n is 1
The above integers, Y is a SO ₂ group or CO group, X is F
Or represents Cl. ): An organic compound capable of dissolving an ionic compound of: and an ion-conductive polymer compound characterized in that the following chemical formulas 5, 6, and 7 are controlled to 0.2 wt% or less in total. The battery that was.

[0022]

Embedded image NH (Y′—C _{n ′} X _{2n ′ + 1} ) ₂

[0023]

Embedded image NH ₂ (Y′—C _{n ′} X _{2n ′ + 1} )

[0024]

Embedded image NH ₄ (Y′—C _{n ′} X _{2n ′ + 1} ) (n ′ is an integer of 1 or more, Y ′ is an SO ₂ group, or C
Represents an O group. )

Further, as a method for forming the composite positive electrode, the electrolyte and the composite negative electrode, the second invention is to form the electrode and the electrolyte by irradiation with actinic radiation such as ionizing radiation. The above object is achieved by providing an electrode by mixing and an ion-conductive polymer compound.

By controlling the above Chemical Formula 5, Chemical Formula 6, and Chemical Formula 7 in the above ion-conductive polymer compound to a total of 0.2 wt% or less, i) When an alkali metal such as lithium is used for the negative electrode ,
The above Chemical Formulas 5, 6 and 7 react with lithium to reduce the generation of H ₂ gas and the like, and the battery does not swell. ii) When a carbonaceous material is used for the negative electrode and LiCoO ₂ , LiNiO ₂ or the like is used for the positive electrode, the reaction between the above chemical formulas 5, 6, and 7 and the above electrode active material is reduced, so that the surface of the electrode active material is reduced. It does not cause formation of a passive film, and does not cause a problem such as deterioration of battery performance. iii) a polymerizable monomer that forms the above-mentioned chemical formula 5, chemical formula 6 or chemical formula 7 when forming the above composite positive electrode, composite negative electrode and electrolyte by irradiation with actinic radiation such as ionizing radiation. I) because it will not react
Or ii) the formation of a passive film on the surface of the electrode active material,
Less generation of H ₂ gas.

The total of the above-mentioned chemical formulas 5, 5, and 7 is 0.2.
The method for controlling the content to be not more than wt% is not particularly limited, but the following method is effective. a) Method using a substance capable of chemisorption; a substance capable of chemisorption (molecular sieves, Al ₂ O ₃ , MgO, Si)
O _2, a column packed with activated carbon, etc.), was added a solution above chemical adsorption substance in the methods and ionic compounds to pass several times a solution of an ionic compound, stirred, and the solution There is a method of repeating the operation of filtering several times. b) A method of synthesizing the above-mentioned imide salt using a high-purity raw material, or a method of optimizing the amount of the raw material during the synthesis. c) A method of chemically reacting the above chemical formulas 5, 6, and 7 to produce a compound that is harmless to the battery reaction. Among the methods a) to c), the method a) or b) is considered to be suitable in view of the problem of the number of steps, the ease of operation, and the like.

Dissolved in the above ion-conducting polymer compound: As the above-mentioned ionic compound, the chemical formula 4 is, for example, LiN (SO ₂ CF ₃ ) ₂ , LiN (COCF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , Li
Examples thereof include, but are not limited to, N (COC ₂ F ₅ ) ₂ , NaN (SO ₂ CF ₃ ) ₂ , NaN (COCF ₃ ) _{2, and the} like. Two or more kinds of these ionic compounds may be used in combination.

Next, in the present invention, the ion conductive polymer compound may contain an organic compound capable of dissolving the ionic compound contained in the ion conductive polymer compound,
By including this kind of substance, the ionic conductivity can be remarkably improved without changing the basic skeleton of the polymer compound. Above: As organic compounds capable of dissolving ionic compounds, cyclic carbonates such as propylene carbonate and ethylene carbonate; cyclic esters such as γ-butyrolactone; tetrahydrofuran or its derivatives, 1,3-dioxane, 1,2-dimethoxyethane ,
Ethers such as methyl diglyme; acetonitrile,
Examples thereof include nitriles such as benzonitrile; dioxolane or a derivative thereof; sulfolane or a derivative thereof alone or a mixture of two or more thereof. However, it is not limited to these. Moreover, the compounding ratio and the compounding method are arbitrary.

The above: The mixing ratio of the ionic compound is 0.0001 to 5.0 mol / liter of the ionic compound with respect to the organic compounds of the above Chemical formulas 1, 2 and 3. It is preferably 0.005 to 2.0 mol / liter. If the amount of the ionic compound used is too large, an excess ionic compound, for example, an inorganic ionic salt, does not dissociate, but merely mixes, resulting in a decrease in ionic conductivity. In addition, the compounding ratio of the ionic compound varies depending on the electrode active material. For example, in a battery using intercalation of a layered compound, it is preferable that the ionic conductivity of the electrolyte is around the maximum, and in a battery using a conductive polymer that utilizes a doping phenomenon as an electrode active material. It is necessary that the ion concentration in the electrolyte can be changed by charging and discharging.

The above: The method of containing the ionic compound is not particularly limited. For example, the organic compound represented by the above chemical formula 1 is dissolved in an organic solvent such as methyl ethyl ketone and uniformly mixed, and then vacuum reduced pressure is applied to the above organic compound. Examples thereof include a method of incorporating the ionic compound in a compound, a method of dissolving the ionic compound in an organic compound capable of dissolving the ionic compound, and then uniformly mixing with the organic compound represented by Chemical formula 1 above.

Further, the ion-conductive polymer compound of the present invention may contain an inorganic compound whose surface is hydrophobized as shown in JP-A-4-245170. The addition of the inorganic compound whose surface is hydrophobized has the following advantages. I) The decrease in ionic conductivity of the ion-conductive polymer compound of the present invention can be suppressed as much as possible. II) Sufficient mechanical strength is obtained in the electrolyte layer, so that a micro short circuit or the like does not occur during battery production.

Silica surface-treated with methyl groups (Japan AE
The surface-hydrophobicized inorganic compound typified by ROSIL AEROSIL R972D) has a surface-hydrophobicized surface and the average primary particle diameter is in the range of 1 μm or less. When it is uniformly mixed with the above, it exhibits an extremely excellent dispersibility and a high thickening effect which are not present in other inorganic compounds, and therefore workability in producing an ion conductive polymer compound thin film is improved.
The surface-hydrophobicized inorganic compound can be dried under reduced pressure at 100 to 300 ° C to remove surface-adsorbed water, if necessary.

Regarding the method for disposing the ion-conductive polymer of the present invention on the surface of the composite positive electrode and the surface of the composite negative electrode, for example, roll coating such as an applicator roll, doctor blade method, screen coating, spin coating, etc. It is desirable to apply a uniform thickness using a means such as a bar coder, but it is not limited thereto. By using these means, it is possible to arrange them on the surface of the composite positive electrode and the surface of the composite negative electrode in any thickness and in any shape.

Further, as the positive electrode active material used in the composite positive electrode of the present invention, the following battery electrode materials can be mentioned. That is, group I metal compounds such as CuO, Cu ₂ O, Ag ₂ O, CuS and CuSO ₄ , group IV metal compounds such as TiS ₂ , SiO ₂ and SnO, V
_{2 O 5, V 6 O 12} , VO X, Nb 2 O 5, Bi 2 O 3, V metal compounds such as _{Sb 2 O 3, Cr0 3,} Cr 2 O 3, MoS 2, WO 3, SeO 2 , etc. VI
Group VII metal compounds such as MnO ₂ and Mn ₂ O ₃
Group VIII metal compounds such as Fe ₂ O ₃ , FeO, Fe ₃ O ₄ , Ni ₂ O ₃ , NiO, CoS ₂ , and CoO, or general formulas Li _X MX ₂ , Li _X
MN _Y X ₂ (M and N are metals of groups I to VIII, X is a chalcogen compound such as oxygen and sulfur), and the like.
For example, a metal compound such as a lithium-cobalt-based composite oxide or a lithium-manganese-based composite oxide, a conductive polymer compound such as polypyrrole, polyaniline, polyparaphenylene, polyacetylene, or a polyacene-based material, a pseudo-graphite structure carbonaceous material Materials and the like, but are not limited to these.

Further, examples of the negative electrode active material used for the composite negative electrode or the alkali metal negative electrode include the following battery electrode materials. That is, as the carbonaceous material such as carbon, those whose analysis results by X-ray diffraction and the like are shown in Table 1 can be used.

[0037]

[Table 1]

Further, carbon powder (average particle diameter of 15 μm or less) or carbon fiber obtained by firing an anisotropic pitch at a temperature of 2000 ° C. or higher is preferable, but it is not limited to these ranges. . Furthermore, lithium metal, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and lithium metal-containing alloys such as wood alloys can be used, but are not limited thereto. is not. These negative electrode active materials can be used alone or in combination of two or more.

When the composite positive electrode is manufactured, several kinds of dispersants and dispersion media are used to obtain a uniform mixed dispersion type coating liquid, or various characteristics of the composite positive electrode (discharge characteristics and charge / discharge cycle characteristics, etc.). It is possible to add a binder for improving Further, it is possible to add a thickener, a bulking agent, an adhesion aid, and the like.

When a binder composed of an organic compound dissolved and / or dispersed in a solvent is used, a binder solution prepared by dissolving the organic compound in a solvent is charged with an electrode active material, the above ion-conductive polymer compound, or the like. A method of using the dispersed material as a coating liquid, or a dispersion liquid of the organic compound and a dispersant for dispersing the organic compound, in which the electrode active material, the ion conductive polymer compound, or the like is dispersed. However, the method is not limited to these.

Examples of the above organic compound include the following. That is, acrylonitrile, methacrylonitrile, vinylidene fluoride, vinyl fluoride,
Examples thereof include polymers such as chloroprene, vinyl pyridine and its derivatives, vinylidene chloride, ethylene, propylene, cyclic dienes (eg, cyclopentadiene, 1,3-cyclohexadiene) and copolymers of the above organic compounds. It is not limited to.

Regarding the method of disposing the composite positive electrode and composite negative electrode of the present invention on the positive electrode current collector and the negative electrode current collector, for example, roll coating such as applicator roll, doctor blade method, spin coating, It is desirable to apply a uniform thickness using a means such as a bar coder, but it is not limited thereto. In addition, when these means are used, it is possible to increase the actual surface area of the electrochemically active substance in contact with the electrolyte layer and the current collector. It can be arranged in any thickness and in any shape.

In these cases, carbon such as graphite, carbon black and acetylene black is used if necessary (the carbon here has completely different characteristics from the carbon in the above-mentioned negative electrode active material). ) And a conductive material such as a metal powder or a conductive metal oxide can be mixed in the composite positive electrode and the composite negative electrode to improve electron conduction.

The ionizing radiation described in the claims is γ
Rays, X-rays, electron rays, neutron rays and the like can be mentioned. The method of using these ionizing radiations in cross-linking the ion conductive polymer compound is very efficient. That is,
In addition to the energy efficiency of the ionizing radiation, for example, when forming an electrolyte (an electrolyte that permeates into the electrolyte layer and the composite positive electrode) composed of an ion conductive polymer compound,
Since the degree of cross-linking of the ion-conductive polymer compound can be easily controlled, it becomes possible to prepare an electrochemically optimal electrode and electrolyte by controlling the dose of the ionizing radiation. .

The positive electrode current collector plate is preferably made of aluminum, stainless steel, titanium, copper or the like, and the negative electrode current collector plate is preferably made of stainless steel, iron, nickel or copper, but is not particularly limited thereto. Absent.

[0046]

EXAMPLES The details of the present invention are described below with reference to examples, but the present invention is not limited thereto. (Example 1) FIG. 1 is a sectional view of a sheet-like battery of the present invention. In the figure, 1 is a positive electrode current collector made of stainless steel,
It also serves as the exterior. An electron conductive layer is provided on the surface of the composite positive electrode side. Reference numeral 2 denotes a composite positive electrode, in which manganese dioxide was used as a positive electrode active material, acetylene black was used as a conductive agent, and ethylene-propylene-1,3-cyclohexadiene copolymer was used as a binder. Further, 3 is an electrolyte layer made of the ion conductive polymer compound of the present invention. Four
Is metallic lithium, and 5 is a negative electrode current collector plate made of stainless steel, which also serves as an exterior. No. 6 is a sealing agent made of modified polypropylene.

The sheet-shaped battery of Example 1 has the following a) to
It is formed through the process of e). Note that a), b),
In order to remove impurities in the lithium bis (trifluoromethylsulfonyl) imide in c) and d), lithium bis (trifluoromethylsulfonyl) imide dissolved in acetonitrile was sufficiently dried to obtain Mg.
The procedure of adding O, stirring, and then filtering was repeated 3 times, and then purification was carried out by completely removing acetonitrile. Impurities in the lithium bis (trifluoromethylsulfonyl) imide used in Example 1 were converted to F ¹⁹ -N.
The results of analysis by MR are shown in Table 2.

A) Using manganese dioxide as the positive electrode active material of the battery and acetylene black as the conductive agent, a xylene solution of ethylene-propylene-1,3-cyclohexadiene and the organic compounds of the following chemical formulas 8, 9 and 10 Was used as a composite positive electrode.

[0049]

[Chemical 8]

[0050]

[Chemical 9]

[0051]

[Chemical 10] The method for producing this composite positive electrode is as follows. That is, a mixture of manganese dioxide and acetylene black in a weight ratio of 85:15 and ethylene-propylene-1,3
Xylene solution of cyclohexadiene copolymer (2 wt
% Solution) was mixed with a dry inert gas (dew point-
Inert gas below 60 ° C. Hereinafter, it is abbreviated as an inert gas. )
Mixed in atmosphere at a weight ratio of 2.2: 2 (Mixture A
₁ ).

This mixture A ₁ and the above Chemical Formulas 8, 9 and 1
Organic compound 10 in which 3: 5: 2 organic compound of 0 is mixed
Parts by weight and lithium bis (trifluoromethylsulfonyl) imide 3.4 parts by weight and propylene carbonate 20
The mixture A _{2 is} mixed with a mixture of ₂ parts by weight in an inert gas atmosphere at a weight ratio of 10: 3.
Got

B) The above mixture A ₂ was cast by screen coating on a positive electrode current collector having an electron conductive layer formed on a stainless steel surface. Then, the composite positive electrode was formed by irradiating an electron beam with an accelerating voltage of 250 kV and an electron dose of 8 Mrad in an inert gas atmosphere. The thickness of the composite positive electrode coating formed on the positive electrode current collector is 60 μm.
Met.

C) Lithium metal was used as the negative electrode active material of the battery, and this was pressed onto a negative electrode current collector plate made of stainless steel. Next, in order to form an ion conductive polymer compound layer on the lithium metal, the above chemical formulas 8, 9 and 10 are formed.
28 parts by weight of an organic compound prepared by mixing the organic compound of 4) in a weight ratio of 4: 4: 2, 9.5 parts by weight of lithium bis (trifluoromethylsulfonyl) imide, 54 parts by weight of propylene carbonate, and surface-treated with a methyl group. Silica (AEROSIL R972D from Japan AEROSIL)
A mixture of 8.5 parts by weight and the above metal was cast by screen coating on the lithium metal described above, and the acceleration voltage was 250 kV and the electron dose was 8 Mrad in an inert gas atmosphere.
Was irradiated with an electron beam to cure. The thickness of the electrolyte layer thus obtained was 25 μm.

D) The sheet-shaped battery of Example 1 was prepared by bringing the electrolyte / lithium / negative electrode current collector obtained in c) into contact with the positive electrode current collector / composite positive electrode / electrolyte obtained in b). It was made.

(Comparative Example 1) The same procedure as in Example 1 was carried out except that the purification step was not provided in Example 1. Table 2 shows the results of F ¹⁹ -NMR analysis of impurities in the lithium bis (trifluoromethylsulfonyl) imide used in Comparative Example 1.

The electrode areas of the sheet-shaped batteries of Example 1 and Comparative Example 1 can be variously changed by the manufacturing process. In Example 1 and Comparative Example 1, the electrode area was 100 cm ² . The thing was produced. Table 2 shows the results of F ¹⁹ -NMR analysis of impurities in the lithium bis (trifluoromethylsulfonyl) imide used in Example 1 and Comparative Example 1. In addition, in the present Example 1 and Comparative Example 1, the following impurities were used for the following impurities:
It was not detected from the organic compounds of Chemical formulas 9 and 10.

[0058]

[Table 2]

After the sheet-shaped batteries of Example 1 and Comparative Example 1 were produced, the number of swollen sheet-shaped batteries when left at room temperature for 240 hours was examined. The results are shown in Table 3.

[0060]

[Table 3]

25 ° C. load of these sheet-like batteries 3 kΩ
The initial discharge characteristics after discharge at 60 ° C and the discharge characteristics after storage at 60 ° C for 100 days were investigated. FIG. 2 shows the discharge characteristics immediately after cell preparation (initial discharge characteristics) and the discharge characteristics after storage at 60 ° C. for 100 days. As is clear from FIG. 2, the sheet-shaped battery of Example 1 of the present invention is superior to the sheet-shaped battery of Comparative Example 1 in initial discharge characteristics and discharge characteristics after storage at 60 ° C. for 100 days. Is recognized. The causes of these phenomena are as follows, although the reaction mechanism has not been clarified. That is, i) NH ₂ SO ₂ CF ₃ or the like reacts with lithium to generate H ₂ gas or the like, so that a swollen cell is generated. ii) When forming the above-mentioned composite positive electrode, composite negative electrode, or electrolyte by irradiation with actinic radiation such as ionizing radiation, NH ₂ SO ₂
It reacts with CF ₃ and a polymerizable monomer that forms an ion-conducting polymer compound, resulting in the formation of a passive film on the surface of the electrode active material, which raises the internal impedance of the battery and swells due to generation of H ₂ gas. A cell occurs.

FIG. 3 shows the relationship between the change in internal impedance of the sheet-shaped battery before and after storage at 60 ° C. for 100 days and the total amount of the above-mentioned impurities. I ₀ is the battery internal impedance before storage, I ₁ is the battery internal impedance after storage, and (I ₁ −I ₀ ) / I ₀ × 100 is the increase rate (%) of the battery internal impedance before and after storage.

From these results, it was possible to improve the characteristics of the sheet-shaped battery by controlling the total amount of impurities in the above-mentioned ion-conductive polymer compound to 0.2 wt% or less.

Although not explicitly shown in this embodiment,
Even when an electrode active material such as LiCoO ₂ or LiNiO _{2 is} used for the composite positive electrode and an electrode active material such as a carbonaceous material and the same ion conductive polymer compound as the present invention are used for the composite negative electrode, the above-mentioned high ion conductivity is obtained. Impurities in the molecular compound are 0.
The same effect was obtained by controlling the content to be 2 wt% or less. Also, the use of, for example, lithium bis (trifluoromethylcarbonyl) imide is within the scope of the present invention.

Further, press, sputtering, suspension,
Thin electrodes can be made by a variety of methods such as coating, which allows the actual surface area of the active material in contact with the electrolyte layer and the current collector to be increased.

Although the above examples and various other descriptions relate primarily to the use of lithium, the use of other alkali metals such as sodium is also within the scope of the invention.

[0067]

As is clear from the above description, the total amount of impurities in the above ion-conductive polymer compound is 0.2 w.
By controlling the concentration to be not more than t%, compared with the ion-conductive polymer compound using the conventional ionic compound, three of ion conductivity, mechanical properties and chemical stability satisfy the practicality at the same time. became. Therefore, the following objectives were achieved. 1) There is no concern about leakage of liquid to the outside and high long-term reliability and safety. 2) It has very high workability. 3) High performance and high energy density. From these, the workability of the battery manufacturing process and the performance of the battery can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a sheet-shaped battery of Example 1 of the present invention.

FIG. 2 shows the initial discharge characteristics and the discharge characteristics of the sheet-shaped batteries of Example 1 and Comparative Example 1 after storage at 60 ° C. for 100 days.

FIG. 3 is a graph showing the relationship between the change in internal impedance of the sheet-shaped battery before and after storage at 60 ° C. for 100 days and the total amount of impurities described above.

[Explanation of symbols]

 1 Positive Electrode Current Collector 2 Composite Positive Electrode 3 Electrolyte 4 Metal Lithium 5 Negative Electrode Current Collector 6 Sealing Material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C08F 299/02 MRS H01M 10/40 A

Claims (1)

[Claims] 1. A composite positive electrode having, as a constituent material, an ion conductive polymer compound containing at least one ionic compound in a dissolved state, an electrolyte comprising the ion conductive polymer compound, and the ion conductive material. A battery comprising a composite negative electrode having a conductive polymer compound as a constituent material or a negative electrode mainly composed of an alkali metal, wherein the ion conductive polymer compound is composed of at least one of the following: ,: At least an organic compound represented by the following chemical formula 1 or / and the following chemical formula 2 or / and the following chemical formula 3 (R ₁ , R ₂ and R ₃ are hydrogen atoms or lower alkyl groups having 1 or more carbon atoms, m and n are m ≧ 1, n ≧ 0, n / m =
Indicates a number in the range 0 to 5. ) (R ₄ , R ₅ , and R ₆ are hydrogen atoms or lower alkyl groups having 1 or more carbon atoms, k and l are k ≧ 3, l ≧ 0, and 1 / k =
Indicates a number in the range 0 to 5. ) [Chemical 3] (R ₇ and R ₈ are hydrogen atoms or lower alkyl groups having 1 or more carbon atoms, and p ₁ , q ₁ , p ₂ , q ₂ , p ₃ and q ₃ are p ₁ ≧ 3, p ₂ ≧ 3 and p, respectively. ₃ ≧ 3, q ₁ ≧ 0, q ₂
≧ 0, q ₃ ≧ 0, q ₁ / p ₁ = number in the range of 0 to 5, q ₂
/ P _{2 is} a number in the range of 0 to 5, q ₃ / p ₃ is a number in the range of 0 to 5, and p ₁ + q ₁ ≧ 10, p ₂ + q ₂ ≧ 1
0, p ₃ + q ₃ ≧ 10. ): An ionic compound represented by the following formula: M ⁺ -N (Y-C _n X _{2n + 1} ) ₂ (M is an alkali metal element such as Li or Na, n is 1)
The above integers, Y is a SO ₂ group or CO group, X is F
Or represents Cl. ): An organic compound capable of dissolving the ionic compound of: and an ion-conductive polymer compound characterized in that the following chemical formulas 5, 6, and 7 are controlled to 0.2 wt% or less in total. The battery that was. Embedded image _{NH (Y'-C n 'X} 2n' + 1) 2 embedded image _{NH 2 (Y'-C n '} X 2n' + 1) embedded image NH ₄ (Y'-C _{n '} X _{2n' + 1} ) (n 'is an integer of 1 or more, Y'is a SO ₂ group, or C
Represents an O group. )