JPH0896840A - Lithium ion secondary battery - Google Patents

Abstract

PURPOSE: To improve stiffness, vibration resistance, and shock.resistance by bundling multiple lug portions of metal materials, pinching them with rod-like metal pieces, and mechanically fastening them. CONSTITUTION: A positive electrode coated with a positive electrode active material mix on a metal material and a negative electrode coated with a negative electrode active material mix on a metal material are laminated in turn across a separator to obtain a unit cell. Lug portions 4', 5 ' of the metal materials of the electrodes of the unit cells are separately bundled and pinched by conductors 8, 11 for the positive electrodes and negative electrodes respectively, and they are fastened by rivets 9, 12. Nonconducting spacers 7 regulating the intervals between the electrodes are inserted into the lug portions 5' of the positive electrode metal materials and the lug portions 4' of the negative electrode metal materials.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium-ion secondary battery, and particularly to a field of large capacity, high energy density, and high maintenance-free demand for electric vehicles, load leveling of electric power, and the like. The present invention relates to a lithium ion secondary battery used in.

[0002]

2. Description of the Related Art In recent years, a lithium ion secondary battery for electronics, which is lightweight and small in size and has a large capacity, has been put into practical use as a power source in response to the downsizing and weight saving of electronic devices. It is used in video cameras, mobile phones, portable personal computers, etc. However, its capacity is large, about 5 to 20 Wh, and many are cylindrical.

On the other hand, electric vehicles are attracting attention from the world due to environmental problems and the need for load leveling of electric power for effectively utilizing night electric power is increasing. Therefore, there is an increasing demand for a secondary battery which has a large capacity, is inexpensive, and is maintenance-free, which is required for these.
However, lead-acid batteries widely used in this field have low energy density, are heavy, and are difficult to use. Further, in terms of maintenance, in addition to the need for water replenishment and the like, the charge / discharge cycle life is as short as about 600 cycles, and as a result, the cost for the battery is high. Nickel in part
Cadmium batteries are also used, but the energy density is not high enough and the cost is higher than lead acid batteries.
Not widely used.

In addition to these, nickel-zinc batteries and sodium-sulfur batteries have also been experimentally used for electric vehicles. However, the former has a short charge / discharge cycle life, and the latter has a high risk. It is contained. The lithium ion secondary battery has a high energy density, is a sealed type, and is maintenance-free, and thus is suitable for these applications, but a large-sized lithium ion secondary battery has not been put into practical use in the past. In order to be used for these purposes, it is necessary to have a capacity of about 1,000 to 5,000 Wh, and it is necessary to make a capacity of 100 times or more that of the conventional one.

Cylindrical type is the mainstream of lithium-ion secondary batteries that have been put into practical use, but the 1,000 to 5,000 Wh class required for electric vehicles, load leveling, etc. is a positive electrode on a metal foil or the like. An assembled battery in which two or more unit cells of 3 to 4 V having a structure in which a positive electrode coated with an active material mixture and a negative electrode coated with a negative electrode active material mixture on a metal foil or the like are alternately laminated with a separator interposed therebetween are connected in series. It becomes the prismatic battery which constitutes.
Such a prismatic lithium ion secondary battery has not yet been put to practical use. Further, conventionally, a large-sized lithium-ion secondary battery having excellent toughness, vibration resistance, and impact resistance, which is suitable for electric vehicles, has not been put into practical use.

[0006]

When a lithium-ion secondary battery is used as a large-capacity secondary battery required for electric vehicles, load leveling, etc., it is first necessary to increase the capacity. . In that case, the lithium ion secondary battery is a so-called prismatic type. This is because each unit cell is composed of several dozen to 100 or more electrodes stacked alternately with a negative electrode and a positive electrode sandwiching a separator. Normally, these unit cells are connected in series to form an assembled battery. .

In particular, when it is used for an electric vehicle or the like, it is required to have a large size and toughness, vibration resistance and impact resistance. For that purpose, the charge / discharge cycle life, toughness, vibration resistance, and impact resistance of the electrodes themselves are required to be high, but the structure of a single cell in which multiple layers of electrodes are stacked also has toughness, vibration resistance, and resistance to shock. It is necessary to devise so that the impact resistance is high. As described above, it is required to increase the size of the lithium ion secondary battery and enhance the toughness, vibration resistance and impact resistance. Therefore, the present inventor has arrived at the present invention by conducting various studies to solve these problems.

[0008]

That is, the gist of the present invention is that a positive electrode in which a positive electrode active material mixture is applied to a metal material and a negative electrode in which a negative electrode active material mixture is applied to a metal material are alternately laminated with a separator interposed therebetween. In a lithium ion secondary battery composed of a single cell having a structure described above, the electrodes are laminated in multiple layers, and the ears of the metal material of the electrodes are separated into a positive electrode and a negative electrode and electrically connected to respective conductors to collect current. In forming the positive electrode and the negative electrode, only one of the ears of the metal material of the positive electrode and the negative electrode is lengthened, and the long ears are sandwiched between the parts coated with the electrode active material mixture, and the positive electrode and the negative electrode are opposite to each other. It is configured so that it goes out to the side, a spacer that regulates the interval between the electrodes is sandwiched between the long ears, the ears of the metal material and the conductor are connected, and a current collector is formed. Characterized by taking out electricity In the lithium ion secondary battery.

The present invention will be described in detail below. First, the constituent elements of the lithium-ion secondary battery in the present invention are at least a negative electrode, a positive electrode, a separator, a non-aqueous electrolyte solution, the negative electrode active material is generally a carbon material capable of intercalation or doping of lithium, The positive electrode active material is a metal oxide compound such as Li _x CoO ₂ that can occlude or intercalate lithium, Li _x
Examples thereof include chalcogenite compounds such as TiS ₂ .

The negative electrode is a negative electrode active material and a binder.
A slurry of [negative electrode mixture] in a solvent is applied to a foil of a metal such as copper, dried, and optionally roll-treated. The positive electrode is obtained by applying a slurry of a positive electrode active material, a binder (binder), and a conductive agent [positive electrode mixture] in a solvent to a metal foil such as aluminum or the like,
It is dried and, if necessary, roll-treated.

As the separator, a thin film of porous synthetic resin, for example, a thin film of polypropylene resin having a thickness of 25 μm, a thin film of polyethylene resin having a thickness of 20 μm, or the like is used, but is not limited to these. is not.
As the non-aqueous electrolyte, a solution obtained by dissolving a lithium salt in an organic solvent is used. The lithium salt is not particularly limited, and examples thereof include LiPF ₆ , LiBF ₄ , LeClO ₄ , and LiAs.
F _6, LiCF ₃ SO _3, and the like. The organic solvent is not particularly limited, for example, carbonates, ethers, ketones, sulfolane compounds, lactones, nitriles, chlorinated hydrocarbons, amines, esters, amides, phosphate ester compounds, etc. Can be used.

Typical examples of these are listed below: propylene carbonate, ethylene carbonate, vinylene carbonate, tetrahydrofuran, 2 methyl tetrahydrofuran, 1,4 dioxane, 4 methyl / 2 pentanone, sulfolane, 3 methyl sulfolane, γ-butyrolactone and dimethoxyethane. , Diethoxyethane, acetonitrile, propionitrile, benzonitrile, butyronitrile, valeronitrile, 1,2 dichloroethane, dimethylformamide, dimethylsulfoxide, trimethyl phosphate, triethyl phosphate and the like and mixed solvents thereof.

As the binder for the negative and positive electrodes, for example, polyvinylidene fluoride, polytetrafluoroethylene, EP
DM (ethylene-propylene-diene terpolymer),
SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluororubber and the like are used, but not limited to these. As the positive electrode conductive agent, fine particles of graphite, carbon black such as acetylene black, fine particles of amorphous carbon such as needle coke,
Etc. are used, but not limited to these.

As a solvent for making the negative electrode mixture of the negative electrode and the positive electrode mixture of the positive electrode into a slurry, an organic solvent capable of dissolving the binder is usually used. For example, N-methylpyrrolidone, dimethylformamide, dimethylacenamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, NN dimethylaminopropylamine, ethylene oxide, tetrahydrofuran, etc. are used, but not limited to these. .

Further, a negative electrode mixture and a positive electrode mixture are slurried by adding a dispersant, a thickener, etc. to water, or SBR.
In some cases, the electrode active material or the like is slurried with a latex such as the above and applied to a metal foil or the like to manufacture an electrode. The negative electrode active material is a carbon material capable of intercalating or doping with lithium, and the carbon material is not particularly limited, and examples thereof include graphite and coal-based coke, petroleum-based coke, carbide of coal-based pitch, and carbide of petroleum-based pitch. Carbides such as needle coke, pitch coke, phenol resin and crystalline cellulose, and the like, and carbon materials obtained by partially graphitizing these, furnace black, acetylene black, pitch-based carbon fiber, and the like.

The positive electrode active material occludes or intercalates lithium.
Metal oxide compounds that can be curated, chalcogena
Ito-based compounds and the like, but are not particularly limited, for example,
Li _xCoO₂, Li_xMnO₂, Li_xMn₂O_Four,
Li_xV₂O_Five, Li_xTiS₂Etc. are used. Negative electrode
The current collector materials are copper, nickel, and stainless steel.
Steel, nickel-plated steel, etc. are used for the positive electrode current collector.
Materials are aluminum, stainless steel, nickel
Plated steel, etc. are used, but are not limited to these
Not of.

The lithium-ion secondary battery in the present invention comprises a single battery in which a positive electrode in which a positive electrode active material mixture is applied to a metal material and a negative electrode in which a negative electrode active material mixture is applied to a metal material are alternately laminated with a separator interposed therebetween. Become. This stacking can be selected according to the purpose, but in order to increase the size of the battery, it is necessary to stack ten or more electrodes, and in some cases, 100 or more multilayers.

As a metal material for applying the active material mixture for the positive electrode or the negative electrode, a thin material such as a metal foil, a metal plate, a metal perforated plate, or a wire net is suitable. In the present invention, when forming the current collector by separating the positive electrode and the negative electrode and electrically connecting the ear portion, which is the portion of the metal material to which the electrode active material mixture is not applied, to the electric conductor. , The ears of the positive and negative metal materials are lengthened on one side only,
The long ears are configured so that the positive electrode and the negative electrode come out on the opposite side by sandwiching the electrode active material mixture-applied part, and the long ears are sandwiched by spacers that regulate the distance between the electrodes. It is configured to connect the ears of metallic material to the conductor to form a current collector and to extract electricity through the conductor.

In this case, the ears of the metal material of the positive electrode and the negative electrode are each made longer, and the long ears are sandwiched between the portions coated with the electrode active material mixture to form the positive electrode and the negative electrode. It is configured so as to appear on the opposite side, and a spacer that regulates the distance between the electrodes is sandwiched between the long ears, and the ears of the metal material are connected to this conductor. Here, in the present invention, the long ears are configured such that the positive electrode and the negative electrode are on the opposite sides of the electrode active material mixture-applied part, and the long ears are provided between the electrodes. Insert a spacer that regulates the space. With such a configuration, both sides of the electrode active material mixture-coated portion of the multilayered electrodes sandwiching the separator can be securely sandwiched, and furthermore, the interval between the electrodes can be regulated and securely fixed. Therefore, a unit cell having a suitable structure can be obtained.

Due to this structure, suitable for upsizing, toughness,
It is possible to obtain a lithium ion secondary battery having high vibration resistance and high impact resistance. In addition, the conductor is often a conductive metal piece. For example, a plurality of metal ear pieces are bundled, and two rod-shaped metal pieces are used to separate the metal ear pieces. By sandwiching and mechanically tightening these,
When forming a current collector, instead of tightening mechanically
When welding the ends of the two rod-shaped metal pieces and the metal material ears, use a conductive spacer and mechanically tighten this part, and use this tightening metal as a conductor and a current collector. There are various forms such as when forming. Also, a conductive carbon material can be used as the material of the conductor.

In the case of forming a current collector by bundling a plurality of metal material ears, sandwiching the metal material ears with two rod-shaped metal pieces, and mechanically tightening these, As a method for securely tightening, caulking with a rivet is preferable, but a method for tightening with a bolt nut, a method for tightening with a clamp or the like is also used. In order to more firmly connect the conductor and the ear portion of the metal material, it is preferable to weld the end portion of the ear portion of the metal material sandwiched between the conductor and the conductor.

As a welding method, TIG welding, high frequency welding or ultrasonic welding is suitable. Mechanical tightening and welding can be used together to connect the conductor and the ear portion of the metal material. Using a conductive spacer, mechanically tighten this part, use this tightening metal as a conductor,
When forming the current collector, as a method of mechanically tightening, a method of tightening with a bolt nut, a method of tightening from the outside of the ear portion of the electrode with a clamp or the like is used.

In the present invention, in order to make the unit cell have a solid structure, in order to keep the positive electrode and the negative electrode alternately sandwiching the separator, in order to keep the intervals between the positive electrode and the positive electrode and between the negative electrode and the negative electrode constant, It is possible to stack by sandwiching the spacer, and the electrode layers of the unit cell can be clamped from the outside. The spacer may use a non-conductive material or a conductive material.

For example, by bundling a plurality of metal material ears, and sandwiching the metal material ears by two rod-shaped metal pieces,
When mechanically tightening these to form a current collector, bundle a plurality of metal material ears, sandwich the metal material ears with two rod-shaped metal pieces, and sandwich with a conductor. When welding the end of the ear portion of the metallic material to the conductor, a conductive material may be used, but it is preferable to use a non-conductive material.

In manufacturing the lithium ion secondary battery of the present invention, when a spacer is sandwiched between electrodes,
The following methods are effective for increasing the productivity. (I) A metal foil or the like of the positive electrode and the negative electrode, to which a spacer is attached in advance with an adhesive, is used. By doing so, by performing the work of laminating the positive electrode, the separator, the negative electrode, the separator, and the positive electrode in this order,
Since the unit cell in which the spacer is sandwiched is completed, the work of sandwiching the spacer is omitted, and the productivity of the manufacturing process of the lithium ion secondary battery is significantly improved.

If a conductive spacer is used, it is necessary to use a conductive adhesive. (Ii) As the spacer, an elongated spacer that matches the length of the electrode in the lengthwise direction is used. By doing so, the number of operations for sandwiching the small spacer is reduced, and the workability is also improved.

[0027]

[Example 1]

(Negative electrode) Coal-based needle coke is crushed to obtain an average particle size of 1
90 parts of 0 μm was added to polyvinylidene fluoride 10
Part is dissolved in 150 parts of N-methylpyrrolidone to form a negative electrode mixture slurry, which is applied to both sides of a copper foil having a thickness of 40 μm, dried to evaporate the solvent, and roll-treated to form a negative electrode. The size of the negative electrode mixture application part is 10c across
m, length 18 cm, and thickness 150 μm on each side. The copper foil doesn't take much ears up and down, but to the left and right, 25m to the left
It is designed so that the negative electrode mixture is applied while leaving a 3 mm ear on the right side. It should be noted that the electrodes constituting the end portions of the unit cells are those in which the negative electrode mixture is applied to only one surface.

(Positive electrode) 1 mol of lithium carbonate and 2 mol of cobalt carbonate were mixed and pulverized in a ball mill, heat-treated in air at 850 ° C. for 5 hours, mixed and pulverized again in a ball mill, and further 850 ° C. in air for 5 hours. Heat-treated with 9
An aluminum foil having a thickness of 80 μm was prepared by adding 5 parts of acetylene black as a conductive agent to 0 part and mixing the mixture with 5 parts of polyvinylidene fluoride dissolved in 150 parts of N-methylpyrrolidone to prepare a positive electrode mixture slurry. Is coated on both surfaces, dried to evaporate the solvent and roll-processed to prepare a positive electrode. The size of the applied portion of the positive electrode mixture was 10 cm in width, 18 cm in length, and 145 μm in thickness. The aluminum foil doesn't take much ears up and down, but 25m to the right on the left and right
It is designed so that the negative electrode mixture is applied while leaving a 3 mm left ear. It should be noted that the electrodes forming the end portion of the unit cell are those in which the positive electrode mixture is applied to only one surface.

(Assembly of Unit Cell) The above-mentioned negative electrode and positive electrode are alternately laminated to sandwich a porous polypropylene sheet having a thickness of 35 μm as a separator to assemble a unit cell. At this time, the electrodes on both ends are prepared by applying the electrode mixture only on one surface. Non-conductive spacers are sandwiched between the negative electrodes on the left negative electrode ears, and non-conductive spacers are also sandwiched on the right positive electrode ears between the positive electrodes. The spacer is sandwiched in three places in the vertical direction on the negative electrode side and the positive electrode side. In this case, in order to improve the workability, a layer in which a non-conductive spacer is adhered to the ear portion of the electrode is used and laminated.

Next, about 15 sheets of end portions of the copper foil of the negative electrode are bundled (the drawing shows an example in which three sheets are bundled), and these are formed by two elongated copper plates (conductors). The end of the end of the ear portion of the copper foil and the two elongated copper plates are welded by TIG welding from the end of the end. Similarly, about 15 end portions of the aluminum foil of the positive electrode are bundled and sandwiched between two elongated aluminum plates (electric conductors),
The tip of the end of the ear portion of the aluminum foil and the two thin strips made of aluminum are welded by TIG welding from the side of the tip of this end. For each single cell, a negative electrode and a positive electrode each having 6 sets (the drawing shows an example of 4 sets) of metal foil and a conductor are welded together. A metal rod is welded to this conductor, and the negative electrode and the positive electrode are separated and connected separately (in parallel). In this way, the negative electrode and the positive electrode are separately connected to form a current collector.

The unit cells are fastened in the stacking direction with a non-conductive frame. In this way, a large-capacity unit cell of a lithium ion secondary battery that is tough and has excellent vibration resistance and impact resistance can be manufactured. 9 electrodes of the above size
By stacking 0 pairs and half (the electrodes on both ends are half because the electrode mixture is applied on only one side), a single cell having a charge / discharge capacity of about 625 Wh is obtained.

The terminals for extracting electricity from the unit cells are metal rods welded to the above-mentioned conductors. In this case, for each unit cell, there are 6 negative electrodes and 6 positive electrodes, respectively. (Shown)), and these are projected from the upper lid of the battery container, and 6 pieces are connected in parallel on the upper lid. 1 to 3 show a cell of the lithium ion secondary battery thus obtained.

FIG. 1 is a plan view of the unit cell (cross section taken along line AA 'in FIG. 3).
5'is divided into four groups and bundled, and the positive electrode and the negative electrode are separately sandwiched between the conductors 8 and 11 and fastened with rivets 9 and 12. 10 and 13 are metal foil ears 4 ',
5'and the conductors 8 and 11 are welded. Conductors 8 and 11
The electrode and the metal foil of the electrode are integrated to form a current collector.

Reference numeral 1 denotes an electrode active material mixture coating portion, and 7 is a portion sandwiching a spacer. FIG. 2 shows an enlarged view of the X part of FIG. That is, it shows the joint between the negative electrode conductor of the negative electrode and the negative electrode metal foil. The positive electrode has the same structure. In this figure,
3 shows a structure in which three negative electrode ears 4'are bundled, sandwiched by conductors 8 and tightened by rivets 9. Reference numeral 10 indicates a welded portion in which the negative electrode ear portion 4'and the conductor 8 are welded.

Reference numeral 2 is a layer of the negative electrode active material mixture, 4 is a negative electrode metal foil, and 4'is a selvage portion of the negative electrode metal foil, which constitute a negative electrode. Reference numeral 3 is a layer of the positive electrode active material mixture, 5 is a negative electrode metal foil, and 5'is an edge portion of the negative electrode metal foil, which constitute a positive electrode. A separator 6 is sandwiched between the negative electrode and the positive electrode. A spacer 7 is sandwiched between the ears 4'of the negative electrode metal foil.

FIG. 3 is a front view of the unit cell. Reference numeral 1 is an electrode active material mixture application portion, and 6 is a separator. Numeral 7 is a spacer, which is the metal foil portion of the electrode 4 ', 5'
Is sandwiched between conductors 8 and 11 and tightened with rivets 9 and 12. Reference numerals 10 and 13 denote welded portions in which the electrode ear portions 4'and 5'and the conductors 8 and 11 are welded. 15 and 17 are negative electrodes,
It is a unit cell terminal of the positive electrode. Electricity is transmitted from the electrode active material mixture to the metal foil, the conductor and the unit cell terminal, and is taken out from the unit cell.

(Assembly of assembled battery) The above-mentioned four unit cells are placed in a polypropylene container having a partition wall, an electrolytic solution is injected, and the upper lid is closed. At this time, the terminal of the negative electrode and the terminal of the positive electrode of each unit cell penetrated through the upper lid and protruded above the container. Six negative terminals (two drawings are shown in the drawing) and six positive terminals for a total of 4 cells per cell
Eight terminals are protruding. The terminal is sealed with an appropriate sealant at the penetrating portion of the upper lid to seal the container. Connect the terminals of each cell in series to connect the terminals (connector)
Connect with and attach the cover.

The positive and negative terminals of the whole assembled battery are brought out of the battery from the side of the battery case. In addition, air or a refrigerant is sent from the outside to the room having the terminal of the unit cell to dissipate the heat generated inside the battery. As the electrolytic solution, a solution prepared by dissolving 1 mol / L of lithium hexafluorophosphate salt in a mixed solvent of propylene carbonate and dimethoxyethane 1: 1 is used.

The charge / discharge capacity of this lithium-ion secondary battery is 2500 Wh, the battery voltage is 14 V, and the energy density is 100 Wh / kg. The assembled battery of the lithium ion secondary battery thus obtained is shown in FIGS. Figure 4
Is a front view (BB 'cross section of FIG. 5), FIG. 5 is a plan view (CC' cross section of FIG. 4), and FIG. 6 is a side view (DD 'cross section of FIG. 5).

Reference numeral 21 indicates a unit cell body. An assembled battery container body 2 having an assembled battery partition wall 25 in which four unit cells are connected in series.
It is housed in the battery pack 2 and separated from the outside by the battery pack cover 23. 15
Indicates a negative electrode unit cell terminal, and 17 indicates a positive electrode unit cell terminal. Adjacent unit cells are set in different + -directions. The middle is connected by the unit battery terminal connecting rod 14, both ends are connected to the assembled battery negative electrode terminal 18 and the assembled battery positive electrode terminal 19, and electricity is taken out of the assembled battery container body.

The heat generated inside the unit cell is transferred to the unit cell terminal chamber by the unit cell terminals of the positive electrode and the negative electrode, and is removed by the refrigerant flowing in this chamber. Reference numeral 24 is a cover of the single cell terminal chamber, 26 is an inlet of the refrigerant, and 27 is an outlet of the refrigerant. Reference numeral 31 is a liquid surface of the electrolytic solution.

[0042]

EFFECTS OF THE INVENTION According to the present invention, a lithium ion secondary battery suitable for upsizing can be obtained.

[Brief description of drawings]

FIG. 1 shows a plan view of an example of a unit cell according to the present invention.

FIG. 2 is an enlarged view of a portion X in FIG.

FIG. 3 is a front view of an example of a unit cell according to the present invention.

FIG. 4 shows a front view of an example of an assembled battery according to the present invention.

5 is a plan view showing a CC ′ cross section of FIG. 4. FIG.

6 is a side view showing a DD ′ cross section of FIG. 5. FIG.

[Explanation of symbols]

 1 Electrode Active Material Mixture Application Section 2 Negative Electrode Active Material Mixture Layer 3 Positive Electrode Active Material Mixture Layer 4 Negative Metal Foil 5 Positive Metal Foil 4 ′ Negative Metal Foil Ear Part 5 ′ Positive Metal Foil Ear Part 6 Separator 7 Spacer 8 Negative Electrode Conductor 9 Negative Electrode Tightening Rivet 10 Negative Electrode Welding Part 11 Positive Electrode Conductor 12 Positive Electrode Tightening Rivet 13 Positive Electrode Welding Part 14 Single Battery Terminal Connecting Rod 15 Negative Single Battery Terminal 17 Positive Electrode Single Battery Terminal 18 Assembly Battery Negative Terminal 19 Battery positive terminal 21 Battery unit body 22 Battery container body 23 Battery container lid 24 Battery terminal compartment cover 25 Battery partition 26 Refrigerant inlet 27 Refrigerant outlet 31 Electrolyte liquid level

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Minor Inoue 1 Fukuda-cho, Joetsu City, Niigata Prefecture Naoetsu Plant, Mitsubishi Kasei Co., Ltd. (72) Tomiichi Koyama 1 Fukuda-cho, Joetsu City, Niigata Mitsubishi Kasei Co., Ltd. in the factory

Claims (9)

[Claims] 1. A lithium ion secondary battery comprising a unit cell having a structure in which a positive electrode in which a positive electrode active material mixture is applied to a metal material and a negative electrode in which a negative electrode active material mixture is applied to a metal material are alternately laminated with a separator interposed therebetween. In forming the current collector by stacking the electrodes in multiple layers and separating the ears of the metal material of the electrode into the positive electrode and the negative electrode and electrically connecting them to the conductors respectively, to form the current collector of the positive electrode and the negative electrode. Only one of the long ears is made long, and the long ears are configured so that the positive electrode and the negative electrode come out on the opposite side by sandwiching the electrode active material mixture application part. A lithium-ion secondary battery characterized in that a spacer that regulates the distance between electrodes is sandwiched between the parts, the ears of the metal material are connected to a conductor to form a current collector, and electricity is taken out through this conductor. . 2. The ears of metal material of the positive electrode and the negative electrode are
2. The lithium-ion secondary battery according to claim 1, wherein the positive electrode and the negative electrode are separated, a plurality of the positive electrodes and the negative electrode are bundled and sandwiched by the conductors, and the conductors are mechanically tightened to form a current collector. 3. The lithium ion secondary battery according to claim 2, wherein the mechanical tightening is performed by caulking a rivet. 4. The ears of metal material of the positive electrode and the negative electrode are
The lithium according to claim 1 or 2, wherein the positive electrode and the negative electrode are separated, and a plurality of the positive electrodes and the negative electrodes are bundled, sandwiched between the conductors, and the ear portion of the electrode is welded to the conductor to form a current collector. Ion secondary battery. 5. The lithium ion secondary battery according to claim 4, wherein welding of the end portion of the ear portion of the electrode and the conductor is performed by TIG welding, high frequency welding or ultrasonic welding. 6. A spacer made of a conductive material is used as the spacer, and the spacer portion is mechanically tightened,
The lithium ion secondary battery according to claim 1, wherein a current collector is formed by using this portion as a conductor. 7. The lithium ion secondary battery according to claim 2, wherein the spacer is made of a non-conductive material. 8. The lithium ion secondary battery according to claim 1, wherein the spacer is made of a metal material and is previously bonded to the ear portion. 9. The lithium ion secondary battery according to claim 6, wherein the spacer is made of a metal material and is previously bonded to the ear portion with a conductive adhesive.