JPH0935721A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery which excels in a current characteristic and has large capacity and excels in self-discharge and cycle characteristics and protection against corrosion by separating electrically conductive means in two places by a specific distance along a peripheral part of a positive electrode collector layer or a negative electrode collector layer. SOLUTION: Collectors 1, 5 or 9 and a positive electrode comprising a positive electrode active material or collectors 3 or 7 are provided in the periphery of each collector of a negative electrode comprising a negative electrode active material and two pieces of positive electrode terminal parts 1', 5', 9', 1", 5", 9" or negative electrode terminal parts 3', 7', 3", 7" are provided in opposite sides so that both of them exist in the farthest position L. It is preferable that two pieces of positive electrode terminals or a negative electrode terminal part exist in the position separated by 3/4L to L to each other and preferably exist in the farthest position L or in its vicinity, where L means a distance between both of them in the case where two pieces of electrically conductive means exist in the farthest position, respectively.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a secondary battery, particularly a lithium secondary battery.

[0002]

2. Description of the Related Art Recent advances in miniaturization, thinning, and weight reduction of electronic devices have been remarkable, and in the OA field, in particular, the size has been reduced from desktop type to laptop type to notebook type. In addition, the field of new small electronic devices such as electronic notebooks and electronic still cameras has also appeared, and in addition to the miniaturization of conventional hard disks and floppy disks, the development of new memory media, memory cards, is underway. In the wave of miniaturization, thinning, and weight reduction of such electronic devices, high performance is also required for secondary batteries that support such electric power. Under such demands, development of lithium secondary batteries as high energy density batteries replacing lead storage batteries and nickel cadmium batteries has been rapidly advanced. Many proposals have been made for a method of collecting current from a secondary battery. For example, an iron alloy containing molybdenum as a current collector (Japanese Patent Laid-Open No. 59-173962) and titanium or titanium-coated metal (Japanese Patent Laid-Open No. 59). -68
169) has been proposed. Further, since the adhesion between the electrode active material and the current collector is important for increasing current collection efficiency, many studies have been made on current collectors for organic secondary batteries. For example, JP-A-58-11227
No. 1 and JP-A-58-189968 disclose carbon-based current collectors, JP-A-59-112584 discloses metal thin film current collectors, and JP-A-58-115777 and JP-A-58-115777. JP-A-58-1157776 reports a method for adhering a current collector and an active material. The inventors of the present invention have also conducted researches on battery mounting, polymer battery current collection method, and capacity improvement, and have already disclosed Japanese Patent Application No. 62-927.
No. 91 improves the adhesion between the current collector and the polymer active material, Japanese Patent Application No. 63-28923 increases the energy capacity of the battery by providing punched holes in the current collector, and PCT / JP88100373 has a sheet-like shape. We are also making proposals to improve the energy capacity by the electrode mounting method (folding method). As described above, the present inventors have conducted research to improve the energy capacity of a battery by improving the current collecting method from the electrode active material and the mounting method.

The applicant of the present application has previously proposed in Japanese Patent Laid-Open No. 2-78152 that the terminals of the positive electrode and the negative electrode are provided in opposite directions, but this method is also sufficient when current collection from the active material is considered. It cannot be said that such consideration has been given. Such a lithium secondary battery includes LiClO ₄ , LiBF ₄ , L
iAsF ₆ , LiPF ₆ , LiSbF ₆ , LiCF ₃ SO ₃
It is well known that an electrolytic solution in which an electrolyte salt such as is dissolved is used. On the other hand, in recent years, LiN (CF ₃ S
It has been proposed to use an electrolyte solution containing O ₂ ) ₂ or LiC (CF ₃ SO ₂ ) ₃ as an electrolyte in a lithium secondary battery [L. A. Dominey, Fifth Inter
national Seminar on Lithi
um Battery Technology and
Applications, March 4-6,
1 (1991)]. These electrolytes are attracting attention as electrolyte salts having excellent self-discharge, load characteristics, and low-temperature characteristics, including the ability to increase ionic conductivity. However, these salts are corrosive and have the drawback of attacking the metal material of the electrode and the metal material of the container, as well as the self-discharge and cycle characteristics of the composite positive electrode (described later) and carbon negative electrode that we have been developing. In terms of the point, it was a salt that could not obtain preferable characteristics.

[0004]

The positive and negative electrodes used in the present invention are a composite of an active material layer on a current collector, and such electrodes are used to form a laminated battery as shown in FIG. , The electrochemical reaction behavior predominates nearer to the terminal. Therefore, the potential (voltage) decreases from the side closer to the terminal. As a result, the actual area where the current can be taken becomes gradually smaller, and when trying to get a constant current value,
The voltage drop is so severe that the power cannot be taken out while leaving a portion where sufficient discharge reaction does not occur. This phenomenon becomes more prominent as a large current is drawn, and for example, in order to increase the capacity of the battery, when the positive and negative electrodes and the separator are folded and stacked as shown in FIG. 2, or when the positive and negative electrodes are simply stacked one by one. That is, as the electrode area increases, the energy efficiency becomes acceleratingly deteriorated. On the other hand, if the positive and negative terminals are arranged on the opposite sides as shown in FIGS. 3 and 4, the electrode reaction will occur relatively uniformly, and the load with a higher energy capacity than that when the terminals are taken from the same end. It is possible to provide a battery with a small voltage drop at the time, but it is not sufficient, and especially when the electrode is long, the electrode reaction is relatively uniform because the terminals are separated, so it is easy to apply the current load. On the other hand, there is a drawback that the battery voltage is easily lowered as a whole. It is considered that this is because it is more difficult for the electrode reaction to occur on the side closer to the center of the electrode, and the battery voltage (electrode potential) decreases while leaving the unreacted portion, and the current cannot be taken out. In view of the above problems, the object of the present invention is to suppress the corrosion of metals when using these salts, and also to provide an electrolyte salt having excellent self-discharge and cycle characteristics in the composite positive electrode of the present invention and the carbon negative electrode. is there.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have adopted a layer structure unit consisting of a positive electrode current collector layer, a positive electrode active material layer, an electrolyte layer, a carbon-based negative electrode active material layer and a negative electrode current collector layer. In a secondary battery configured to have more than one, an electrically conductive means is provided at each of two positions of all the positive electrode current collector layer and the negative electrode current collector layer of the above-mentioned layer structure unit, It is possible to solve the above technical problem by allowing the conductive means to be separated by 3 / 4L to L along the peripheral portion of the positive electrode current collector layer or the negative electrode current collector layer provided with the electrically conductive means. Found and arrived at the present invention. (However, L means the distance between the two electrically conductive means when they are at the most distant positions.) Hereinafter, the configuration of the secondary battery of the present invention will be described with reference to the drawings. This will be specifically described. However, the secondary battery of the present invention is not limited to the one shown in the drawings. In FIG. 5, current collector 1,
Two positive electrode terminal portions 1 ′, 5 ′, 9 ′, 1 ′ around each positive electrode or current collector 3 or 7 composed of the positive electrode active material layer 5 or 9 and negative electrode composed of the negative electrode active material layer. ″,
5 ", 9" or negative electrode terminal portions 3 ', 7', 3 ", 7"
Are provided on the opposite sides so that the two are present at the most distant position L. It is preferable that the two positive electrode terminal portions or the negative electrode terminal portions are present at positions separated from each other by 3 / 4L to L, preferably at the most separated position L or in the vicinity thereof. FIG. 6 shows another embodiment of the present invention. In the layer structure shown in FIG. 5, the one shown in FIG. 6 has two positive electrode terminal portions 1 ′, 5 ′, 9 ′, 1 ″,
5 ", 9" or negative electrode terminal portions 3 ', 7', 3 ", 7"
Is provided at an apex angle instead of the opposite side so that the two are present at the most distant position L.

As the electrolyte salt of the lithium battery, one that is soluble in a non-aqueous solvent and exhibits high ionic conductivity is used. Examples of such a cation include an alkali metal ion. Examples of anions include Cl ⁻ , Br ⁻ , I ⁻ , SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF.
_{^{6 -, SbF 6 -, CF}} 3 SO 3 -, (CF 3 SO 2) 2 N - can be exemplified. Among these electrolyte salts, LiN (C) has high ionic conductivity, excellent load characteristics and low temperature characteristics.
It is preferred to use F ₃ SO ₂ ) ₂ . However,
LiN (CF ₃ SO ₂ ) ₂ has a corrosive property, which is remarkable especially when the positive electrode current collector layer is made of aluminum, and it has been found from the study in the present invention that the elution current of aluminum changes when an electric field is applied. ing. As a result of studying to suppress the corrosiveness, it was found that the corrosiveness can be suppressed by adding other electrolyte salt to LiN (CF ₃ SO ₂ ) ₂ . As the electrolyte salt to be added, the addition of an electrolyte salt composed of a combination of the above-mentioned cation and anion was effective, but from the viewpoint of preventing corrosion and matching with the composite positive electrode and composite negative electrode of the present invention, more preferably BF as anion. ₄ ^- surprisingly salt having a combination of alkali metal ions or alkaline earth metal ion or tetraalkylammonium ions other than lithium was found that preferred as and cation have. That is, in a preferred embodiment of the present invention, LiN (CF ₃ SO ₂ ) ₂ as an electrolyte salt and at least 1 represented by the following formula
The use of a mixed electrolyte with the seed electrolyte.

Embedded image M (BF ₄ ) x (I) (R ¹ R ² R ³ R ⁴ ) NBF ₄ (II) (wherein M is an alkali metal or an alkaline earth metal, x
Is 1 or 2, and R ¹ , R ² , R ³ and R ⁴ are the same or different alkyl groups)

T is used as a positive electrode active material of a lithium secondary battery.
iS ₂ , MoS ₂ , CoO ₂ , V ₂ O ₅ , FeS ₂ , Nb
Many examples of transition metal oxides such as S ₂ , ZrS ₂ , and MnO ₂ or transition metal chalcogen compounds, in which an inorganic material is used as an active material, have been studied. Such a material is capable of electrochemically reversibly taking lithium ions in and out of its structure, and the lithium secondary battery has been developed by utilizing this property. Since a lithium secondary battery using such an inorganic material as an active material generally has a high true density of the active material itself, it is easy to construct a battery having a high energy density, and lithium occlusion and release are reduced into the crystal structure of the active material. In the case of the intercalation and deintercalation, there is a feature that a battery having excellent voltage flatness can be easily formed. On the other hand, when more than necessary lithium ions are accumulated in the crystal structure, the crystal structure is destroyed and the function as the active material of the secondary battery is significantly deteriorated. This means that the secondary battery electrode is vulnerable to overdischarge. Recently, in the process of developing a lithium secondary battery using such an inorganic material as an active material, the electrode reaction can be performed by reversibly absorbing and releasing anions as a potential electrode active material of the lithium secondary battery. There was a discovery of conducting polymer that can be done. The conductive polymer is lightweight as an electrode material and has characteristics such as high output density, and also has excellent current collecting properties due to the conductivity, which is a unique property of the material, and exhibits high cycle characteristics even at a discharge depth of 100%. Further, it has characteristics that the inorganic material does not have, such as good moldability as an electrode.

Examples of the conductive polymer include polyacetylene (for example, JP-A-56-136489), polypyrrole (for example, 25th Battery Symposium, Abstracts, P25).
61, 1984), polyaniline (for example, 50th Conference of the Electrochemical Society of Japan, Proceedings, P2281, 1984).
Etc. have been reported. The lithium secondary battery has a technical problem of developing a negative electrode in addition to the above-described development of the positive electrode. Conventionally, lithium and lithium aluminum alloys have been used for the negative electrode of lithium secondary batteries.However, lithium has the disadvantage of poor charge / discharge cycle characteristics and the danger of short-circuiting due to dendrites. Although it can be secured to some extent, it has the drawback that it is difficult to make a high-voltage battery because the potential of the material moves in a noble direction and there is no flexibility. For this reason, recently, a lithium secondary battery using a carbon material capable of inserting and extracting lithium as a negative electrode has attracted attention, and research and development have been vigorously conducted. This battery is called a lithium ion battery. The positive electrode active material used in the battery of the present invention is TiS ₂ , MoS ₂ ,
Transition metal oxides such as Co ₂ S ₅ , V ₂ O ₅ , MnO ₂ and CoO ₂ , transition metal chalcogen compounds and complexes thereof with Li (Li complex oxides; LiMnO ₂ , LiMn ₂ O ₄ ,
LiCoO ₂ etc.), a one-dimensional graphitized product which is a thermal polymer of an organic substance, carbon fluoride, graphite, or a conductive polymer having an electrical conductivity of 10 ⁻² S / cm or more, specifically polyaniline, polypyrrole, Polyazulene, polyphenylene, polyacetylene, polyacene,
Polymers such as polyphthalocyanine, poly-3-methylthiophene, polypyridine, and polydiphenylbenzidine, and derivatives thereof can be mentioned, but they show high cycle characteristics even at a discharge depth of 100%, and are comparatively superior to inorganic materials. It is preferable to use a conductive polymer that is resistant to discharge. In addition, since the conductive polymer is a plastic in terms of moldability, it is possible to take advantage of a characteristic that has not been available in the past. Although the conductive polymer has the above advantages, the secondary battery using the conductive polymer as the positive electrode has a low volume energy density due to the low density of the active material. In order to perform a smooth charge / discharge reaction, an excessive amount of electrolyte is necessary for the electrode reaction, and since the change in the electrolyte concentration with the charge / discharge reaction is large, there is a large change in the electrolyte resistance. There is a problem that a liquid is required. This is disadvantageous in improving the energy density.

On the other hand, it is conceivable to use the above-mentioned inorganic chalcogenide compound or inorganic oxide in the positive electrode as an active material having a high volume energy density. However, these are diffusion rates of cations in the electrode due to an electrode reaction accompanying charging and discharging. Is slow, rapid charge / discharge is difficult, and reversibility against over-discharge is poor,
There is a problem that the cycle life is reduced. In addition, since it is difficult to mold the inorganic active material as it is, it is often molded by pressure using a tetrafluoroethylene resin powder or the like as a binder, but in that case, the mechanical strength of the electrode can be said to be sufficient. In addition, with respect to overdischarge, if lithium ions are excessively accumulated, the crystal structure will be destroyed, and the secondary battery will not function. In order to solve such a problem, it is possible to use an organic and inorganic composite active material. In this case, the polymer active material used is required to exhibit high electrical conductivity due to electrochemical doping, and the electrode material is required to have an electrical conductivity of 10 ⁻² S / cm or more. Also, high ionic conductivity is required in terms of diffusivity of ions. These polymer materials have a high electric conductivity to have a current collecting ability, a binding ability as a polymer, and also function as an active material. In addition, since the conductive polymer is insulated at a low potential, even when the composite positive electrode is in an overdischarged state, the conductive polymer is insulated so that unnecessary lithium ions are contained in the inorganic active material contained therein. It prevents accumulation and prevents destruction of the crystal structure of the inorganic active material. As a result, an electrode that is substantially resistant to overdischarge can be formed. The conductive polymer used for the composite positive electrode is a material that has the ability as an active material, does not dissolve in an electrolytic solution, has a binding property between polymer materials, and exhibits conductivity. An inorganic active material is fixed as an agent. At this time, the inorganic active material becomes a form that is entirely covered by the conductive polymer, and as a result, the entire area around the inorganic active material becomes conductive. Examples of such a conductive polymer include redox active materials such as polyacetylene, polypyrrole, polythiophene, polyaniline, and polydiphenylbenzidine. Particularly, a nitrogen-containing compound is particularly effective. These conductive polymer materials are required to have high ionic conductivity in terms of not only conductivity but also diffusion of ions. Among them, polypyrrole, polyaniline and copolymers thereof are preferred because they have a relatively large electric capacity per weight and can be charged and discharged relatively stably in a general-purpose nonaqueous electrolyte. More preferred is polyaniline. The inorganic active material used for the composite positive electrode is preferably one having excellent potential flatness, and specifically, an oxide of a transition metal such as V, Co, Mn, or Ni or a composite oxide of the above transition metal and an alkali metal is used. Examples of the electrode potential stable in the electrolytic solution, voltage flatness,
Taking energy density into consideration, crystalline vanadium oxide is preferable, and vanadium pentoxide is particularly preferable. The reason is that the potential flat portion of the discharge curve of crystalline vanadium pentoxide is relatively close to the electrode potential associated with the insertion and desorption of the anion of the conductive polymer.

A carbonaceous material is used as the negative electrode material used in the battery of the present invention. Examples of the carbonaceous negative electrode active material include graphite, pitch coke, synthetic polymer, and a sintered body of natural polymer. In the present invention, synthetic polymer such as phenol and polyimide, or natural polymer is used.
Conductivity obtained by firing an insulating or semiconducting carbon body, coal, pitch, synthetic polymer or natural polymer obtained by firing in a reducing atmosphere at 800 to 1300 ° C. in a reducing atmosphere at 800 to 1300 ° C. Carbon body,
2000 for coke, pitch, synthetic polymer, natural polymer
What is obtained by firing in a reducing atmosphere at a temperature of ℃ or more, and a graphite-based carbon body such as natural graphite is used, but a carbon body is preferable. Among them, mesophase pitch and coke are fired in a reducing atmosphere of 2,500 ° C or more. The resulting carbon body has excellent potential flatness and has favorable electrode characteristics. As the positive electrode current collector used in the present invention, for example, stainless steel, gold, platinum, nickel,
Examples thereof include metal sheets such as aluminum, molybdenum, and titanium, metal foils, metal nets, punching metals, expanded metals, and nets and non-woven fabrics made of metal-plated fibers, metal vapor-deposited wires, metal-containing synthetic fibers, and the like. Of these, aluminum and stainless steel are particularly preferable in consideration of electrical conductivity, chemical stability, electrochemical stability, economic efficiency and workability. Aluminum is more preferable because of its lightness and electrochemical stability. Further, the surfaces of the positive electrode current collector layer and the negative electrode current collector layer used in the present invention are preferably roughened. By roughening, the contact area of the active material layer is increased, and the adhesion is also improved, which has the effect of lowering the impedance of the battery. Further, in the production of an electrode using a coating solution, it is possible to greatly improve the adhesion between the active material and the current collector by subjecting it to a surface roughening treatment. Examples of the surface roughening treatment include polishing with an emery paper, blasting, and chemical or electrochemical etching, whereby the current collector can be roughened. In particular, in the case of stainless steel, blast processing is preferable, and in the case of aluminum, etched aluminum is preferable. Since aluminum is a soft metal, an effective surface roughening cannot be performed by blasting, and aluminum itself is deformed.
On the other hand, the etching treatment can effectively roughen the surface in the order of micrometer without deforming the aluminum or greatly reducing the strength thereof, and is the most preferable method for roughening the aluminum.

An organic non-aqueous polar solvent is used as the electrolytic solution used in the present invention, and an organic non-aqueous polar solvent which is aprotic and has a high dielectric constant is preferable. Specific examples thereof include, but are not limited to, propylene carbonate, ethylene carbonate, γ-butyl lactone, dimethyl sulfoxide, dimethylformamide, dimethoxyethane, dimethoxycarbonate, and diethoxycarbonate. The organic non-aqueous polar solvent may be used alone or in combination of two or more. The electrolyte concentration cannot be unconditionally specified because it varies depending on the positive electrode used, the electrolyte and the type of the organic non-aqueous polar solvent, etc., but is usually in the range of 0.1 to 10 mol / liter. Examples of the solid electrolyte used in the present invention include AgCl in an inorganic system,
Metal halides such as AgBr, AgI, LiI, R
Examples thereof include bAg ₄ I ₅ and RbAg ₄ I ₄ CN ionic conductors. Also, in organic systems, polyethylene oxide,
Polypropylene oxide, polyvinylidene fluoride, polyacrylonitrile, etc. are used as a polymer matrix to dissolve the electrolyte salt, or crosslinked products of these, ion-dissociating groups such as low molecular weight polyethylene oxide, polyethyleneimine and crown ether are used as the polymer main chain. Examples include grafted polymer solid electrolytes. Alternatively, a gelled polymer solid electrolyte having a structure in which the high molecular weight polymer contains the electrolytic solution is used. The gelled polymer solid electrolyte is a solid electrolyte that is obtained by adding a polymerizable compound to an ordinary electrolytic solution and polymerizing the compound by heat or light. More specifically, WO91 / 14294
The ones described are used. Acrylate as a polymerizable compound (eg methoxydiethyl glycol methacrylate, methoxydiethylene glycol diacrylate)
A system compound is polymerized using a polymerization disclosing agent such as benzoyl peroxide, azobisisobutyronitrile, methylbenzoyl formate, and benzoin isopropyl ether to solidify the electrolytic solution. Among such solid electrolytes, it is preferable to use a gel polymer solid electrolyte from the viewpoint of ionic conductivity and flexibility. The electrolyte salt used for the gelled solid electrolyte is not particularly limited, but is dissolved in a non-aqueous solvent,
Those exhibiting high ionic conductivity are used. Examples of such a cation include an alkali metal ion. As the anion, Cl ⁻ , Br ⁻ ,
I ⁻ , SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ ,
Examples include CF ₃ SO ₃ ⁻ and (CF ₃ SO ₂ ) ₂ N ⁻ . A mixed electrolyte composed of LiN (CF ₃ SO ₂ ) ₂ and a salt of tetrafluoroborate represented by the above formulas (I) and / or (II) is preferable. Although an organic non-aqueous polar solvent is used as the electrolytic solution, an organic non-aqueous polar solvent that is aprotic and has a high dielectric constant is preferable. Specific examples thereof include propylene carbonate, γ-butyl lactone, dimethyl sulfoxide, dimethylformamide, ethylene carbonate, dimethoxyethane, dimethyl carbonate, diethyl carbonate and the like. The organic non-aqueous polar solvent may be used alone or in combination of two or more. Preferred is a mixed solvent of two or more kinds of propylene carbonate, ethylene carbonate and dimethyl carbonate. The concentration of the electrolyte varies depending on the type of the positive electrode, the electrolyte and the organic non-aqueous polar solvent to be used, and cannot be unconditionally specified. However, it is usually preferable to be in the range of 0.1 to 10 mol / l. A separator can also be used in the battery of the present invention. As the separator, it is preferable to use a separator that has a low resistance to the movement of ions of the electrolyte solution and is excellent in retaining the solution. Examples of such a separator include a glass fiber, a filter, a non-woven fabric filter made of polymer fibers such as polyester, Teflon, polyflon, and polypropylene, and a non-woven fabric filter made by mixing glass fibers and these polymer fibers.

[0012]

【Example】

Example 1 Using a stainless steel sheet 4 × 7.5 cm (polymerized part) having a through hole of 0.9 mmφ that had been subjected to a blast treatment of 20 μm as a reaction electrode in a 3 M HBF ₄ aqueous solution containing aniline, at 3 mA / cm ² Polymerized on both sides. The terminal was arranged at the same position as the positive electrode in FIG. The stainless polyaniline electrode was washed with running water and then washed with 0.2 N sulfuric acid at -0.4
The potential was applied up to V vs SCE to perform sufficient dedoping operation. This was reduced with a 20% hydrazine aqueous solution, washed and dried to obtain a polyaniline electrode (thickness 660 μm). Further, two positive electrodes in which polyaniline was polymerized on only one surface were produced by the same method. A total of three prepared positive electrodes except the terminal portion were fixed by covering the entire active material layer by forming a polypropylene pore filter into a cylindrical shape.
Then 7 of propylene carbonate and dimethoxyethane
LiN (CF ₃ SO ₂ ) ₂ was added to the 1/3 (volume ratio) mixed solution.
97M, NaBF ₄ 0.03M dissolved electrolyte 8
4.9%, ethoxydiethylene glycol acrylate 14.77%, trimethylolpropane triacrylate 0.23%, benzoin isopropyl ether 0.1
The polyaniline was thoroughly impregnated with the solution mixed at a ratio of 100%, and the solution was irradiated with light from a high-pressure mercury lamp. The electrolyte was solidified, and the liquid did not exude even when pressure was applied. These were used as positive electrode members. Blast-treated stainless steel (SUS304) consisting of 47.4 parts by weight of carbon obtained by firing coke at 2500 ° C., 5.2 parts by weight of polyvinylidene fluoride, and 47.4 parts by weight of n-methylpyrrolidone. It was applied onto a current collector and dried at 80 ° C. to form a 20 μm-thick negative electrode active material layer (4 × 7.5 cm) on both sides. After inserting lithium ions into carbon, the mixed solution was permeated and irradiated with a high pressure mercury lamp to completely solidify the electrolytic solution. Two sheets of this were produced and used as a negative electrode member. A positive electrode member and a negative electrode member are laminated so as to have a layer structure as shown in FIG. 5, and 1 ′, 5 ′, 9 ′ and 1 ″, 5 ″, 9 ″ and 3 ′, 7 ′ and 3 ″, 7 ″ are stacked. A battery was completed by sealing the entire laminated body under reduced pressure with a heat-sealing film containing an aluminum core material when conducting a charge and discharge test on this secondary battery. The initial capacity was 45 mAh.
(20 mA discharge) and 40 mAh (60 mA discharge), self-discharge was 8.5% / month, and the cycle until the capacity became 2/3 was 305 times.

Example 2 A stainless steel positive electrode current collector which was blasted with a coating solution consisting of 9.9 parts by weight of polyaniline, 23.1 parts by weight of crystalline V ₂ O _{5 and} 67 parts by weight of n-methylpyrrolidone. A thickness of 120 applied to the body and dried at 120 ° C
A positive electrode active material having a thickness of μm (both sides) and 60 μm (one side) was formed. The negative electrode active material layer was 60 μm (both sides). A battery was produced in the same manner as in Example 1 except for this. Initial capacity of secondary battery is 60mAh (30mA discharge) and 55mA
h (90 mA discharge), self-discharge is 6.3% / month,
The cycle was 371 times.

Example 3 A battery was manufactured in the same manner as in Example 2 except that the terminal portion was arranged as shown in FIG. The initial capacity of the secondary battery is 61 mAh (30
mA discharge) and 60 mAh (90 mA discharge).

Comparative Example 1 A battery was manufactured in the same manner as in Example 2 except that the terminal portions were 1 ', 5', 9'and 3 ', 7'in FIG. Initial capacity of secondary battery is 60mAh (30mA discharge) and 40mA
It was h (90 mA discharge).

Comparative Example 2 A battery was manufactured in the same manner as in Example 2 except that the terminal portion was changed as shown in FIG. The initial capacity of the secondary battery is 60 mAh (30 mA
Discharge) and 51 mAh (90 mA discharge).

Comparative Example 3 A battery was prepared in the same manner except that the electrolyte salt used in Example 1 was 2M LiBF ₄ . The initial capacity of the secondary battery is 40.5m
It was Ah (30 mA discharge), self-discharge was 11% / month, and the cycle was 245 times.

Example 4 A battery was prepared in the same manner as in Example 2 except that etched aluminum was used as the positive electrode current collector layer. The initial capacity of the secondary battery is 61.5 mAh and self-discharge is 8.0% /
The cycle was 315 times a month.

Comparative Example 4 A battery was prepared in the same manner as in Example 4 except that 2M concentration of LiN (CF ₃ SO ₂ ) ₂ was used as the electrolyte salt. The initial capacity of the secondary battery was 60.5 mAh, but the cycle 20
After the turn, there was only 16 mAh, and it was found that dissolution of aluminum occurred when disassembling.

Example 5 A battery was prepared in the same manner as in Example 2 except that 1.98M LiN (CF ₃ SO ₂ ) ₂ and 0.02M KBF ₄ were used as the electrolyte salt. The initial capacity of the secondary battery is 59.5m
Ah, self-discharge is 7.1% / month, cycle is 36
It was once.

Example 6 A battery was prepared in the same manner as in Example 2 except that 1.98M LiN (CF ₃ SO ₂ ) ₂ and 0.02M tetrabutylammonium tetrafluoroborate (C ₄ H ₉ ) ₄ NBF ₄ were used as electrolyte salts. Was produced. The initial capacity of the secondary battery is 62
mAh, self-discharge is 6.8% / month, cycle is 3
It was 81 times.

[0022]

According to the present invention, it is possible to provide a lithium secondary battery having excellent current characteristics and high capacity, and excellent self-discharge, cycle characteristics, and corrosion resistance.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an arrangement of electrodes, separators and electrode terminals of a known secondary battery.

FIG. 2 is a diagram showing an arrangement of electrodes, separators and electrode terminals of an example of a known secondary battery when electrodes and separators are folded and laminated.

FIG. 3 is a diagram showing an example of the arrangement of electrodes, separators and electrode terminals of the secondary battery of the present invention.

FIG. 4 is a diagram showing an arrangement of a secondary battery in which one positive and negative electrode terminal is arranged on opposite sides of a positive electrode and a negative electrode current collector, respectively.

5 is a diagram showing an arrangement of electrodes, separators and electrode terminals of the secondary battery of Example 1. FIG.

FIG. 6 is a diagram showing the arrangement of electrodes, separators, and electrode terminals of the secondary battery of Example 3.

7 is a diagram showing the arrangement of electrodes, separators, and electrode terminals of the secondary battery of Comparative Example 2. FIG.

[Explanation of symbols]

 A positive electrode B positive electrode terminal portion C separator layer D negative electrode E negative electrode terminal portion 1 current collector + positive electrode active material layer 1 ′ positive electrode terminal portion 1 ″ positive electrode terminal portion 2 separator layer 3 current collector + negative electrode active material layer 3 ′ negative electrode terminal Part 3 ″ negative electrode terminal part 4 separator layer 5 current collector + positive electrode active material layer 5 ′ positive electrode terminal part 5 ″ positive electrode terminal part 6 separator layer 7 current collector + negative electrode active material layer 7 ′ negative electrode terminal part 7 ″ negative electrode terminal part 8 Separator layer 9 Current collector + positive electrode active material layer 9 ′ Positive electrode terminal portion 9 ″ Positive electrode terminal portion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuo Katagiri 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Hiroyuki Iechi 1-3-6 Nakamagome, Ota-ku, Tokyo In stock company Ricoh (72) Inventor Yoshitaka Hayashi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh company (72) Inventor Tomohiro Inoue 1-3-6 Nakamagome, Tokyo Ota-ku Ricoh company (72) Inventor Toshiyuki Kabata 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd.

Claims (5)

[Claims] 1. A secondary battery comprising two or more layer structure units each comprising a positive electrode current collector layer, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer and a negative electrode current collector layer. , All of the positive electrode current collector layer and the negative electrode current collector layer of the layer structure unit are provided with an electrically conducting means, and the two electrically conducting means are provided with the electrically conducting means. A secondary battery, which is present at a distance of 3/4 L to L along a peripheral portion of the positive electrode current collector layer or the negative electrode current collector layer. (However, L means the distance between the two electrically conductive means when the two electrically conductive means are present at the most distant positions.) 2. The secondary battery according to claim 1, wherein the negative electrode active material layer is a carbon-based negative electrode active material layer. 3. The secondary battery according to claim 1, wherein the positive electrode current collector layer and the negative electrode current collector layer have a quadrangular shape, and the two electrically conductive means have a quadrangular vertical angle or opposite sides. Secondary battery installed in. 4. The secondary battery according to claim 1, 2 or 3, wherein LiN (CF ₃ S) is used as the electrolyte of the electrolyte layer.
A secondary battery using a mixed electrolyte of O ₂ ) ₂ and at least one tetrafluoroborate salt represented by the following formula (I) and / or (II). Embedded image M (BF ₄ ) x (I) (R ¹ R ² R ³ R ⁴ ) NBF ₄ (II) (wherein M is an alkali metal or alkaline earth metal, x
Is 1 or 2, and R ¹ , R ² , R ³ and R ⁴ are the same or different alkyl groups) 5. The secondary battery according to claim 1, 2, 3 or 4, wherein the positive electrode current collector is etched aluminum.