JPH1186833A - Cylindrical secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent short circuits in a battery and to improve safety, quality, and productivity of the battery by providing current collector lugs which are not coated with electrode mix over the entire length of the same side end section of an electrode group, fitting leads to them, and sticking an insulating adhesive tape to cover the entire length of the current collector lugs. SOLUTION: A positive electrode 1 and a negative electrode 4 coated with a positive electrode mix 3 and a negative electrode mix 6 are wound on both faces of a positive electrode current collector 2 and a negative electrode current collector 5 via a wide separator 7 to form an electrode group 11, this is stored in a battery case 20, and an electrolyte is filled. Current collector lugs 2a, 5a which are not coated with electrode mix are provided over the entire length of the same side end sections of the belt-like positive and negative electrodes 1, 4, positive and negative electrode leads 8, 9 are fitted to them, and a positive electrode terminal 14 and a negative electrode terminal 15 are extracted from them in one direction. A insulating adhesive tape 10 is stuck to the current collector lugs 2a, 5a over nearly the entire length so as to cover the end face edge sections of the current collector lugs 2a, 5a from above the lead wires 8, 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to mobile devices such as electric vehicles and electric carts, portable devices such as video cameras and personal computers, backup devices in the event of a power outage, and power storage devices.
And prevention of an internal short circuit between electrodes of a medium / large secondary battery used as a power source for products such as security equipment.

[0002]

2. Description of the Related Art In a conventional cylindrical secondary battery, an electrode group in which a strip-shaped positive electrode and a negative electrode are spirally wound via a separator is housed in a cylindrical battery case, and a positive electrode lead is placed on the lid side of the battery case. The negative electrode lead was welded to the bottom of the battery case. For the purpose of preventing the internal short circuit between the electrodes of the battery, as shown in JP-A-4-301361, at the end of an electrode group in which a strip-shaped positive electrode and a negative electrode are spirally wound via a separator, In some cases, a rubber-like synthetic resin is applied in a state where lead wires from electrodes are projected, and then the synthetic resin is cured to form a resin coating layer.

In order to prevent the generation of lithium dendrite, as disclosed in Japanese Patent Application Laid-Open No. 3-129678, in a battery in which a positive electrode and a lithium negative electrode are wound with a separator interposed, the edge of the lithium negative electrode faces The edge of the positive electrode is coated with an insulating member having the same thickness as the electrode mixture.

[0004]

However, JP-A-4-301361 has a structure in which the entire end face of a spirally wound electrode group is covered with a synthetic resin, and JP-A-3-129678 discloses a spirally wound electrode group. Since both ends of the positive electrode of the spirally wound electrode group are covered with an insulating member having a thickness of the positive electrode mixture, in the electrolyte injection step after insertion into the battery case, the electrode group of the electrolyte from the spirally wound electrode group end face is inserted. There is a problem that penetration into the inside is hindered by the insulating member coated on the end face. Also, JP-A-4-301
In both JP-A-361 and JP-A-3-129678, one electrode terminal is taken out to the lid side of the cylindrical case and the bottom of the can, and the electrode terminal is wound in both directions of the spirally wound electrode group. The structure is such that lead wires of different polarities come out.

Further, in order to achieve a structure in which both electrode terminals are taken out by a plurality of leads in one direction of the spirally wound electrode group, which is the terminal structure of the present invention, there are the following problems. That is, the electrode mixture provided on the same side of the current collector is applied in order to short-circuit due to the contact of the plurality of positive and negative leads and to weld the positive and negative leads to the current collector made of metal foil. Since the current collector ears in a bare state are insulated only by the thin film separator, the separator may be damaged by the current collector edge and a short circuit between the positive and negative electrodes may occur.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to prevent internal short circuit of a battery, improve safety and quality of the battery, and improve productivity. It is to provide a good cylindrical secondary battery.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a current-collecting ear without an electrode mixture at the same side end of a strip-shaped positive electrode and a negative electrode. After connecting a plurality of positive electrode leads and negative electrode leads to the ear part, and attaching an insulating adhesive tape thinner than the electrode mixture to the current collector ear part from above the lead wire, the positive electrode and the negative electrode are separated via a separator. The electrode group was spirally wound. In addition, the positive electrode lead and the negative electrode lead are arranged so as to be substantially aligned in the radial direction from the same end face of the wound electrode group, respectively, and the power generation element composed of the electrode group and the electrolyte is housed in a bottomed cylindrical battery case. Then, insert an insulating distant having a separating plate for insulating and separating the positive electrode lead and the negative electrode lead between the electrode group and the lid, and connect each electrode to each electrode terminal penetrating through the lid with a lead wire,
The battery case is sealed with a lid.

According to the present invention, even in a cylindrical battery in which the positive and negative electrode terminals are provided in one direction, the edges of the current collector ears between the positive and negative electrodes are covered with the insulating adhesive tape,
Also, since the positive and negative electrode lead wires are reliably insulated by the insulating-destination separating plate, a short circuit between the positive and negative electrodes inside the battery can be prevented. Furthermore, since the end surface of the wound electrode group is not blocked by the insulating adhesive tape, the electrolyte easily penetrates into the positive / negative electrode mixture application portion even in the electrolyte injection step, and the productivity is good.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a cylindrical secondary battery according to the present invention will be described below with reference to the drawings, taking a lithium ion secondary battery as an example. FIG. 1 is a structural vertical sectional view showing one embodiment of a cylindrical secondary battery of the present invention, FIG. 2 is a perspective view of a wound electrode group of FIG. 1, and FIG. 3 is a perspective view of an insulating distant. In FIG. 1, reference numeral 1 denotes a positive electrode, and a positive electrode mixture 3 (for example, as an active material) using an inorganic lithium intercalation / deintercalation material as a positive electrode active material on both surfaces of a positive electrode current collector 2 made of a strip-shaped aluminum foil. LiMn ₂ O ₄ ,
As a conductive material such as LiCoO ₂ and LiNiO ₂ , carbon,
(Polyvinylidene fluoride mixed and adjusted as a binder) is applied and pressed and held.

A positive electrode mixture 3 is provided at one end of the positive electrode current collector 2.
Positive electrode current collector ears 2a as they are without applying aluminum foil
Is over the entire length. Reference numeral 4 denotes a negative electrode, and a negative electrode mixture 6 (for example, graphite as an active material, a graphite material, a lithium-intercalation / de-intercalation carbon material) formed on both surfaces of a negative electrode current collector 5 made of a strip-shaped copper foil. (Adhesion of polyvinylidene fluoride mixed and adjusted) is applied and pressed and held.

The negative-electrode current collector 5 also has a negative-electrode current-collector ear 5a on the same side as the positive-electrode current-collector ear 2a, which is not coated with the negative-electrode mixture 6 and remains in the form of a copper foil base. . The ears of the current collector are coated with the mixture containing the active material from the beginning, or after the mixture is pressed after applying the mixture, the solvent mixture is added to the electrode mixture to be removed.
-Preparation by impregnating with methylpyrrolidone or the like to remove the applied active material mixture. Reference numeral 7 denotes a separator made of a microporous thin film or a nonwoven fabric of a thermoplastic resin such as polyethylene or polypropylene. When the temperature of the polyethylene film rises, the shutdown start temperature at which the microporous closes due to the melting of the film itself is about 1 °.
30 ° C., and the shutdown initiation temperature of the polypropylene film is about 150 ° C. In other words, when the temperature of the battery rises due to an abnormal state such as an internal short circuit or an external short circuit,
The thermoplastic resin of the separator melts, causing microporous or non-woven fabric to be clogged, and shuts off the movement of ions between the positive and negative electrodes to cut off the battery current and protect the battery.

The positive electrode 1 and the negative electrode 4 are spirally wound in a state where they face each other with the separator 7 interposed therebetween, thereby forming an electrode group 11. In this case, the separator 7 is composed of the positive electrode 1 and the negative electrode 4
The separator 7 is wound a few times at the winding core and the end of the winding by the separator 7 alone to provide insulation between the positive electrode and the negative electrode and around the electrode group. The electrode group 11 is immersed in an electrolytic solution (not shown) to become a power generating element.

The above-mentioned electrolytic solution is composed of LiPF ₆ , LiBF ₄ , L
A solution in which a lithium salt such as iClO ₄ or LiAsF _{6 is} dissolved as an electrolyte in an organic solvent (single or a mixture of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, etc.) is used.

Reference numeral 20 denotes a battery case made of stainless steel, nickel-plated iron, nickel-plated copper, or aluminum. The power generating element including the electrode group 11 and the electrolyte is housed in a bottomed cylindrical container, and the lid 21 is covered. The opening of the battery case 20 is sealed by welding or the like. The lid 21 is preferably made of the same material as the battery case because it is welded to the battery case. Insulating plates 13a and 13b are provided on the container bottom 20a and the lid 21 side in the battery case 20 in order to maintain electrical insulation between the battery charging section and the battery case 20 and the lid 21.

Reference numeral 8 denotes a strip-shaped aluminum material positive electrode lead, which is connected to the positive electrode current collector ear 2a of the positive electrode 1 and the aluminum material positive electrode terminal 14 by welding or the like. Reference numeral 9 denotes a strip-shaped nickel or copper negative electrode lead, which is connected to the negative electrode current collector ear 5a of the negative electrode 4 and a nickel or copper negative electrode terminal 15 by welding or the like. It should be noted that a single positive electrode lead 8 and a negative electrode lead 9 cannot provide a sufficient current capacity for a medium or large battery, so that a plurality of lead wires must be connected.

In order to output a plurality of positive and negative lead wires in the same direction, the positive electrode lead 8 and the negative electrode lead 9 are wound so that they do not come into contact with each other. It is desirable that a plurality of leads be arranged. In other words, the one-row arrangement of the lead wires allows the positive electrode lead 8 and the negative electrode lead 9 to be separately separated and bundled, and also facilitates the work from the viewpoint of the connection processing to the terminals and the insulation between the positive and negative electrodes.

Reference numeral 10 denotes an insulating pressure-sensitive adhesive tape, which is made of an electrolytic solution-resistant resin material such as polyethylene, polypropylene, polyimide, and polyphenylene sulfide. The insulating adhesive tape 10 covers substantially the entire lengths of the positive electrode current collector ears 2a and the negative electrode current collector ears 5a so as to cover the edge edges of the current collector ears 2a and 5a from above the positive electrode lead 8 and the negative electrode lead 9, respectively. It is pasted over.

Accordingly, it is possible to prevent the thin film separator from being damaged due to burrs and edges on the end faces of the exposed current collector ears of the aluminum foil or the copper foil, resulting in insulation failure and to prevent the lead and the current collector from being damaged. It has the function of reinforcing the mechanical bonding strength with the body. FIG. 4 shows an example in which the insulating adhesive tape 10 is applied over substantially the entire length so as to cover the edges of the current collector ears from both surfaces of the current collector ears 2a and 5a of the positive electrode and the negative electrode. Is an example in which an insulating adhesive tape 10 is attached to one of the current collector ears of the positive electrode and the negative electrode from both sides.

In any of these embodiments, at least one or more insulating adhesive tape 10 is used to insulate and protect between the positive and negative electrode current collector ears 2a and 5a. The thickness of the insulating pressure-sensitive adhesive tape 10 is made smaller than the thickness of the mixture 3, 6 of each electrode applied and pressed on the current collectors of the positive electrode and the negative electrode. Thereby, the spirally wound outer diameter of the electrode group 11 is set to the positive electrode 1, the negative electrode 4,
It is determined only by the thickness of the separator 7, and can be wound tightly without a gap between the positive electrode and the negative electrode, and a battery with stable performance can be obtained. In the subsequent electrolyte injection step, since the current collector ears, which are the cylindrical end faces of the electrode group 11, are thinner than the electrode mixture application section, the electrolyte passes through the gaps between the electrode group 11 end faces and the electrode mixture application section. Easy to penetrate.

Reference numeral 12 denotes a cylindrical insulating destant.
A separating plate 12a for insulating and separating the positive electrode lead 8 and the negative electrode lead 9 is provided in the cylinder between the electrode group 11 and the lid 21 to secure an independent space for accommodating each electrode lead wire, and the electrode group 11 is It keeps it from moving inside. Therefore, the plurality of positive electrode leads 8 and negative electrode leads 9 are separated from each other by the separation plate 12a, and the insulation is maintained without contact.

The positive terminal 14 and the negative terminal 15 are
And a hermetic seal 1 that is electrically insulated and hermetically sealed by interposing a glass or plastic layer.
The portion which is fixed through through the terminal case and comes out of the terminal case becomes an electric connection portion with the outside. Explosion-proof hole 21 provided in lid 21
a is sealed with an explosion-proof valve 18 made of a metal plate or a thin-film metal plate having a weak point such as a notch.
When the internal pressure of the battery 1 becomes high due to an abnormal temperature rise, the battery 1 is opened, and the battery case 20 is prevented from exploding.

Next, a method of assembling the cylindrical secondary battery according to the present invention will be described. First, the strip-shaped positive electrode 1 and negative electrode 4 having current collector ears on one side are spirally wound through the separator 7 with the current collector ears in the same direction.
At this time, the necessary number of positive electrode leads 8 are attached to the positive electrode current collector ears 2a and the negative electrode leads 9 are attached to the negative electrode current collector ears 5a by spot welding or ultrasonic welding, respectively. The insulating adhesive tape 1 is applied to the positive electrode current collector ear 2a and the negative electrode current collector ear 5a from above the negative electrode lead 9.
The positive and negative electrodes are wound while affixing 0 so that the edge of the current collector ear end is covered.

At this time, the number of lead wires to be attached is increased or decreased depending on the battery capacity. The welding position of the lead wire to the electrode is calculated by correcting the thickness and winding diameter of both the electrode and the separator while spirally winding the positive electrode 1, the negative electrode 4, and the separator 7, and then sequentially determining the welding position of the lead wire and welding. As a result, the rows of the positive electrode lead 8 and the negative electrode lead 9 can be arranged substantially in a row in the radial direction in the state of the wound electrode group.

As described above, the strip-shaped lead wires 8, 9 are welded to the current collector ears 2a, 5a, which do not affect the winding diameter, so that the lead wires 8, 9 are arranged in a line. The electrode group 1 is insulated and protected by the tape 10 and is reinforced and fixed.
The positive / negative electrode mixture of the electrodes 3 and 6 should not be disturbed.
To fit within the thickness of

As described above, the positive electrode 1 and the negative electrode 4 are wound through the separator 7 while adding the positive electrode lead 8, the negative electrode lead 9 and the insulating adhesive tape 10. create. Therefore, the application of the insulating adhesive tape is performed simultaneously with the electrode winding step, so that the productivity is good.

Next, the insulating plate 13a, the electrode group 11, and the insulating distant 12 are placed in this order from the bottom 20a side of the bottomed cylindrical container, and the positive electrode lead 8 and the negative electrode lead 9 are bundled and put together. On the other hand, the insulating plate 13b is placed on the back side of the lid 21 of the battery, and the positive electrode lead 8 and the negative electrode lead 9 are welded to the positive terminal 14 and the negative terminal 15 of the lid 21. When joining these leads and welding to terminals, if the leads are joined to the current collector with insulating adhesive tape and are not reinforced by attaching to the current collector, a current collector made of thin aluminum foil or copper foil must be used. There is a risk of breakage at the lead wire weld.

Next, an electrolytic solution is injected from the opening of the battery case 20, and the cover 21 is put on the battery case 20 to cover the battery case 2.
The battery assembly is completed by sealing the opening of No. 0 and the lid 21 by welding. However, in order for the battery to be in a chargeable state, it is necessary to allow the electrolyte to completely penetrate the positive and negative electrode mixture. In the case of the present invention, the thickness of the insulating adhesive tape attached to the current collector ears is thinner than the thickness of the positive and negative electrode mixture, so there is a gap at the end face of the wound electrode group, and it is tightly wound. The electrolyte solution easily enters the positive and negative electrode mixture portions, and the standing time after the electrolyte solution injection step can be shortened, so that the productivity can be greatly improved.

[0028]

As described above, according to the present invention, a plurality of positive electrode leads and negative electrode leads are welded to the current collector ears on the same side end of the strip-shaped positive electrode and negative electrode where the electrode mixture is not applied. Then, an insulating adhesive tape of an electrolytic solution-resistant material was attached so as to cover the edge of the end face of the current collector ear, and the positive electrode and the negative electrode were wound through a separator to form an electrode group. Therefore, it is possible to prevent the separator from being damaged by the edge of the current collector ear, and to prevent a short circuit between the positive and negative electrodes,
By reinforcing the connection between the lead wire and the current collector, the lead wire can have strength enough to withstand handling in the work process.

The positive electrode lead and the negative electrode lead are arranged in a line in the radial direction from the same end face of the spirally wound electrode group, respectively, are pulled out, are connected to the positive electrode terminal and the negative electrode terminal, and are insulated from the positive electrode lead and the negative electrode lead. Was provided between the electrode group and the battery lid having the electrode terminals. Therefore, a short circuit between the positive and negative lead wires can be prevented.

Further, since the thickness of the insulating adhesive tape is made smaller than the thickness of the positive and negative electrode mixture, the impregnation with the electrolyte becomes easy, and the winding adhesion of the positive and negative electrode electrode mixture application portions is improved. Battery performance is improved. Furthermore, the winding diameter at the time of winding the electrode group is stable, the accuracy of the correction calculation of the welding position of the lead wire to the electrode while winding is accurate, and the leads can be arranged substantially in a line in the wound state.

[Brief description of the drawings]

FIG. 1 is a structural sectional view showing one embodiment of a cylindrical secondary battery of the present invention.

FIG. 2 is a perspective view of the electrode group of FIG.

FIG. 3 is a perspective view of the insulating detent of FIG. 1;

FIG. 4 is a sectional view showing another embodiment of the electrode group of the cylindrical secondary battery of the present invention.

FIG. 5 is a sectional view showing still another embodiment of the electrode group of the cylindrical secondary battery of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Positive electrode, 2 ... Positive electrode current collector, 2a ... Positive electrode current collector ear part, 3
... Positive electrode mixture, 4 ... Negative electrode, 5 ... Negative electrode current collector, 5a ... Negative electrode current collector ear, 6 ... Negative electrode mixture, 7 ... Separator, 8 ... Positive electrode lead, 9 ... Negative electrode lead, 10 ... Insulating adhesive tape , 11 ...
Electrode group, 12: insulating destant, 12a: separating plate, 13
a, 13b: insulating plate, 14: positive terminal, 15: negative terminal, 17: hermetic seal, 18: explosion-proof valve, 20:
Battery case, 20a: bottom of container, 21: lid, 21a: explosion-proof hole.

Continued on the front page (72) Inventor Toyooka Okawa 800, Tomita, Odai-machi, Ohira-machi, Shimotsuga-gun, Tochigi Prefecture Inside the Cooling Division, Hitachi, Ltd. Within the business division

Claims (1)

[Claims] 1. A belt-shaped thermoplastic resin wider than the width of the positive electrode and the negative electrode between the positive electrode and the negative electrode formed by applying and pressing a positive electrode mixture and a negative electrode mixture on both surfaces of a positive electrode current collector and a negative electrode current collector. In a cylindrical secondary battery in which a group of electrodes wound through a separator made of a microporous thin film is housed in a bottomed cylindrical battery case, and positive and negative electrode terminals are taken out in one direction, the same band-shaped positive electrode and negative electrode are used. After providing the current collector ears that do not apply the electrode mixture over the entire length of the side end, and after electrically attaching a plurality of positive electrode leads and negative electrode leads to the ears,
A cylindrical secondary battery, wherein an insulating adhesive tape is attached to the current collector ears over substantially the entire length so as to cover the edge of the end surface of the current collector ears from above the lead wire.