JPH11354111A - Cylindrical nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical nonaqueous electrolyte battery having high safety by preventing a short circuit of the inside of the battery due to a burr of a metal collector of a positive electrode plate. SOLUTION: In this cylindrical nonaqueous electrolyte battery provided with a spiral electrode body composed by winding a band-like negative electrode formed from lithium or lithium alloy and a band-like positive electrode composed by retaining a positive electrode mix by a metal collector interposing a separator, this battery has a structure wherein a non-woven fabric made of resin is arranged on an end in the lengthwise direction of the electrode of the positive electrode 1 and an end in the height direction of the battery, and in this case, at least one resin selected from a group consisting of polyethylene, polypropylene, polyamide 6, polyethylene terephthalate, polybutylene terephthalate and phenylene sulfide is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder provided with a spiral electrode group formed by winding a positive electrode plate using a metal current collector and a negative electrode plate using lithium or a lithium alloy via a separator. The present invention relates to a non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art A non-aqueous electrolyte battery using lithium or a lithium alloy as a negative electrode active material and a non-aqueous electrolyte as an electrolyte has a low potential of about -3 V. Boasts a higher discharge voltage than batteries such as batteries. In particular, a non-aqueous electrolyte battery using manganese dioxide or fluorocarbon as a positive electrode active material is widely known as a 3V battery, and its use is also performed by operating a camera from a backup power supply for a memory of an electronic device. It covers a wide variety of fields from power supply for use, and the shape from coin shape to cylindrical shape is selected according to the intended use.

In general, a cylindrical non-aqueous electrolyte battery contains a group of electrode plates formed by winding a belt-like positive electrode plate and a negative electrode plate disposed in between with a separator in a longitudinal direction in a bottomed cylindrical battery case. Adopt a configuration that The positive electrode plate used for the cylindrical non-aqueous electrolyte battery is a metal current collector using expanded metal or the like cut into a mesh, and a positive electrode mixture comprising a mixture of a positive electrode active material, a conductive agent, and a binder. After being held, it is created by cutting it into a predetermined shape.

[0004] Since the cutting of the positive electrode plate into a predetermined shape is performed by punching, burrs are generated in the cut portion of the metal current collector at the peripheral edge of the positive electrode plate. At the time of battery assembly,
By spirally winding the positive electrode plate and the negative electrode plate, the tip of the burr is exposed on the surface of the positive electrode plate. When the burr breaks through the separator and comes into contact with the negative electrode plate, an internal short circuit occurs and abnormal heat generation may occur. further,
After assembling the battery, when the positive electrode expands or vibrates or falls due to the use of the battery, burrs may break through the separator and come into contact with the negative electrode, causing an internal short circuit as in the case of assembly.

[0005]

Various methods have been proposed to prevent the occurrence of an internal short-circuit caused by burrs on the metal current collector portion as described above. For example, Japanese Unexamined Patent Publication
Japanese Patent No. 20707 discloses a method of forming an inorganic coating film mainly composed of a metal oxide such as zirconia oxide or alumina oxide at an end of a positive electrode plate to prevent short-circuiting due to burrs generated in a metal current collector. Prevention has been proposed. However, in this method, a portion coated with the coating film is formed on the positive electrode active material, so that the positive electrode active material coated on the coating film cannot participate in the reaction, and the reaction area contributing to the battery reaction decreases, and the battery There was a problem that the capacity was reduced.

A method of attaching a tape to an end of a positive electrode plate has also been proposed. However, there is a problem that the reaction area is reduced because the tape covers the positive electrode active material as in the above method, and the battery capacity is reduced.

The present invention solves the above-mentioned problems in the cylindrical non-aqueous electrolyte battery, and prevents internal short circuit of the battery due to burrs generated in the metal current collector portion of the positive electrode plate, thereby improving safety. It is an object of the present invention to provide a cylindrical non-aqueous electrolyte battery that is high and does not decrease battery capacity.

[0008]

In order to achieve the above object, a cylindrical nonaqueous electrolyte battery according to the present invention comprises a strip-shaped negative electrode made of lithium or a lithium alloy and a positive electrode mixture held on a metal current collector. In a non-aqueous electrolyte battery provided with an electrode body obtained by winding a strip-shaped positive electrode plate and a separator through a separator, a nonwoven fabric made of resin is arranged on the peripheral edge of the positive electrode plate and covered. .

Preferably, the material of the resin forming the nonwoven fabric is at least one resin material selected from the group consisting of polyethylene, polypropylene, polyamide 6, polyethylene terephthalate, polybutylene terephthalate, and polyphenylene sulfide.

In addition, the method of coating the end of the positive electrode with a nonwoven fabric made of a resin is as follows. The raw resin of the nonwoven fabric in a heated and melted state is applied to the longitudinal end of the belt-shaped positive plate and the end in the battery height direction. The coating is performed simultaneously with the formation of the nonwoven fabric on the electrode plate by blowing out the filaments with a high-speed and high-temperature air flow. By applying this coating method from both sides of the belt-shaped positive electrode plate, the entire peripheral edge of the positive electrode plate is coated.

With this configuration, the burr generated at the cut portion of the metal current collector of the positive electrode plate can be covered with a resin nonwoven fabric to prevent an internal short circuit from occurring, and this nonwoven fabric inhibits a discharge reaction. Since it is made of a material that does not have any adverse effect on the discharge reaction, the battery capacity is not reduced because it does not adversely affect the discharge reaction.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below for the sake of understanding.

According to the first aspect of the present invention, a strip-shaped negative electrode made of lithium or a lithium alloy and a strip-shaped positive electrode plate in which a positive electrode mixture is held on a metal current collector are used as a separator made of a resin non-woven fabric. The negative electrode and the spirally wound electrode group wound in the longitudinal direction of the positive electrode, in a cylindrical nonaqueous electrolyte battery housed in a bottomed cylindrical battery can,
It is characterized in that the peripheral edge of the positive electrode is covered with a nonwoven fabric using a resin forming the separator.

According to a second aspect of the present invention, a strip-shaped negative electrode made of lithium or a lithium alloy and a strip-shaped positive plate in which a positive electrode mixture is held on a metal current collector are arranged via a separator. A cylindrical nonaqueous electrolyte battery in which a spiral electrode group wound in the longitudinal direction of the positive electrode is housed in a bottomed cylindrical battery can, and the peripheral edge of the positive electrode is formed of polyethylene, polypropylene, polyamide 6, It is characterized in that it is covered with a non-woven fabric using at least one resin selected from polyethylene terephthalate, polybutylene terephthalate and polyphenylene sulfide.

With this configuration, even when burrs are formed on the metal current collector when forming the belt-like positive electrode plate, the burrs formed are covered with a nonwoven fabric made of resin, and the burrs are separated by the separator. Does not penetrate. Therefore, the occurrence of an internal short circuit can be prevented, and a highly safe cylindrical nonaqueous electrolyte battery can be provided.

The resin materials selected from the group consisting of polyethylene, polypropylene, polyamide 6, polyethylene terephthalate, polybutylene terephthalate, and polyphenylene sulfide are all less affected by the non-aqueous solvent used in the electrolytic solution. Even if a nonwoven fabric is arranged on the positive electrode plate because it does not inhibit the reaction, it does not inhibit the battery reaction in the active material in the positive electrode mixture,
There is no adverse effect on battery characteristics such as a decrease in discharge capacity.

Further, the portion where the nonwoven fabric made of resin is disposed has a larger thickness of the electrode plate than other portions of the electrode plate, but does not affect the binding rate of the battery. It is preferable that the portion covered with the nonwoven fabric is formed within about 5 mm from the end of both ends in the longitudinal direction of the electrode of the positive electrode plate and both ends in the height direction of the battery.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the nonaqueous electrolyte battery according to the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 shows a positive electrode plate 1 in a cylindrical nonaqueous electrolyte battery according to the present invention. A fluorinated graphite as a positive electrode active material, a conductive agent and a binder were mixed in a weight ratio of 100: 1.
The mixture was mixed at a ratio of 0: 4 to prepare a positive electrode mixture. The obtained positive electrode mixture was pressure-bonded to a metal current collector with a roller and formed into a sheet. The positive electrode mixture was held by the metal current collector, and cut into a certain size. In addition, a mixture exfoliated portion was provided at the center of the strip-shaped positive electrode plate.

On one surface of the obtained electrode plate, a heated and melted polypropylene is blown into a thread shape by a high-speed and high-temperature air flow to each of a longitudinal end portion of the electrode plate and an end portion of the battery in a height direction. To form Subsequently, by forming a coating portion also on the other surface, the peripheral edge of the positive electrode plate was coated with a nonwoven fabric. Thereafter, the positive electrode current collecting lead plate 1b was welded to the mixture separation portion, and an insulating tape was stuck to the separated portion and the surface of the lead plate 1b to produce the positive electrode plate 1.

Using the obtained positive electrode plate, a cylindrical non-aqueous electrolyte battery shown in FIG. 4 was prepared. In FIG. 4, reference numeral 2 denotes a negative electrode plate, and in this embodiment, lithium metal was used. Reference numeral 3 denotes an outer can, which is formed in a bottomed cylindrical shape. Reference numeral 4 denotes a separator made of a nonwoven fabric of polypropylene. This nonwoven fabric was formed in a bag shape, and after enclosing the positive electrode plate, the opening edge of the separator was thermally welded. The positive electrode plate in Example 1 has its peripheral edge covered with a nonwoven fabric made of the same resin as the separator.

The negative electrode plate 2 cut into a predetermined size made of lithium metal is pressed on both sides to a separator 4. The positive electrode plate 1 and the negative electrode plate 2 accommodated in the bag-shaped separator 4 were spirally wound to obtain a group of electrode plates, which were housed in a 2 / 3A-sized outer can 4. The electrolyte used was a solution in which lithium borofluoride was dissolved at 1 mol / l in γ-butyrolactone.

(Example 2) The peripheral edge of the positive electrode plate 1 in Example 1 was covered with a non-woven fabric made of polyethylene.
In other respects, a battery having the same configuration as the battery in Example 1 was prepared.

(Example 3) The peripheral edge of the positive electrode plate 1 in Example 1 was covered with a nonwoven fabric made of polyamide 6,
In other respects, a battery having the same configuration as the battery in Example 1 was prepared.

Example 4 A battery having the same structure as the battery in Example 1 except that the peripheral edge of the positive electrode plate 1 in Example 1 was covered with a nonwoven fabric made of polyethylene terephthalate. .

Comparative Example 1 A positive electrode plate 10 to which a tape was attached was prepared by replacing the peripheral edge of the positive electrode plate in Example 1 with a nonwoven fabric. This is shown in FIG. With respect to the positive electrode plate coated with the positive electrode mixture and punched into a predetermined shape, a tape 10a made of polypropylene was attached to a portion located on the outermost periphery of the positive electrode plate when the electrode plate group was formed. The other configuration is the same as that of the battery in Example 1, and the positive electrode current collecting lead plate 10b is welded to the mixture release portion provided at the center of the positive electrode plate, and an insulating tape is attached to the separated portion and the surface of the lead plate. Thus, a positive electrode plate 10 was produced. Using this positive electrode plate 10, a cylindrical battery was produced in the same manner as in Example 1.

(Comparative Example 2) Further, a belt-shaped positive electrode plate before disposing a nonwoven fabric at the end of the positive electrode plate of the positive electrode plate 1 was prepared.
The positive electrode current collecting lead plate 30b was welded to the mixture release portion provided at the center of the positive electrode plate, and an insulating tape was attached to the separated portion and the surface of the lead plate to produce the positive electrode plate 30. This positive electrode plate 30
Is shown in FIG. Thereafter, a battery was manufactured in the same manner as in Example 1.

With respect to the obtained batteries of each of the examples and the comparative examples, a drop test after discharging was performed. In this test, after discharging to about 50% of the nominal capacity, the open circuit voltage was measured, and then a drop test was performed. In the drop test, the sample was dropped on concrete 10 times from a point having a height of about 5 m. After this drop test, the open circuit voltage was measured again. At this time, a battery whose open-circuit voltage after the drop test was 0.1 V or more lower than that before the test was defined as a low-voltage battery. Table 1 shows the rate of occurrence of voltage drop when the drop test after discharge was performed in each of the examples and the comparative examples. During discharge, the positive electrode expands due to the discharge, the distance to the negative electrode becomes shorter, and the probability of an internal short circuit increases as compared to an undischarged battery.

[0029]

[Table 1]

As shown in (Table 1), in each of Examples 1 to 4, a battery using an electrode in which a nonwoven fabric made of resin was disposed at the cut portion of the positive electrode plate, and a tape on the strip-shaped positive electrode plate of Comparative Example 1 were used. The battery using the attached electrode has no voltage drop. On the other hand, in Comparative Example 2 in which the electrode at the end of the positive electrode plate was not subjected to the burring countermeasure, a voltage drop occurred.

From the results of this test, it was found that the strip-shaped positive electrode plate used in each of the examples had a non-woven fabric made of resin at the longitudinal end of the electrode and the height end of the battery, so that the metal collection of the positive electrode was possible. Even when burrs of the electric body occurred, it was possible to prevent an internal short circuit that breaks through the separator and comes into contact with the negative electrode, and a highly safe cylindrical non-aqueous electrolyte battery was obtained. .

Next, Example 1, Comparative Example 1 and Comparative Example 2
Of the non-aqueous electrolyte battery was discharged at a constant resistance of 1 kΩ in a 20 ° C. atmosphere, and the discharge capacity was measured. The result is shown in FIG.

As a result, the battery capacity of Example 1 and Comparative Example Battery 2 was not reduced as compared with Comparative Example Battery 1.
It is considered that the reaction area of Comparative Example 1 was reduced because the tape was stuck on the positive electrode active material. Therefore, in Example 1, even if the nonwoven fabric made of resin was disposed at the cut portion of the positive electrode plate, there was no effect of inhibiting the discharge reaction of the battery.

In this example, good results were obtained even when the material of the resin nonwoven fabric was at least one selected from the group consisting of polyethylene, polyamide 6, polyethylene terephthalate, polybutylene terephthalate, and polyphenylene sulfide. I have.

The method of disposing the resin-made non-woven fabric at the end of the strip-shaped electrode plate is not limited to the above-described method, and the resin-made non-woven fabric is disposed at the end of the strip-shaped electrode plate. , Good results have been obtained.

[0036]

According to the present invention, the end portions in the longitudinal direction of the electrode of the strip-shaped positive electrode in which the positive electrode mixture is held on the metal current collector and the end portion in the height direction of the battery are made of polyethylene, polypropylene or polyamide. 6. Although polyethylene terephthalate is used, polybutylene terephthalate or polyphenylene sulfide may be used. By disposing a non-woven fabric combining at least one resin selected from the group of these resins, even if burrs are generated at the end of the belt-shaped positive electrode plate, the burrs are covered with a non-woven fabric made of resin. It is possible to prevent a short circuit inside the battery caused by the burr of the current collector piercing the separator and coming into contact with the negative electrode, thereby providing a highly safe battery. Further, the resin nonwoven fabric is made of a material that does not inhibit the discharge reaction of the battery, and a cylindrical non-aqueous electrolyte battery that does not adversely affect the discharge reaction and does not reduce the discharge capacity is obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a front view of a positive electrode plate according to an embodiment of the present invention.

FIG. 2 is a front view of a positive electrode plate in Comparative Example 1.

FIG. 3 is a front view of a positive electrode plate in Comparative Example 2.

FIG. 4 is a cross-sectional view of a cylindrical nonaqueous electrolyte battery according to the present embodiment and a comparative example.

FIG. 5 is a discharge curve diagram in Example 1, Comparative Example 1 and Comparative Example 2.

[Description of Signs] 1 positive electrode plate 2 negative electrode plate 2 3 outer can 4 separator

Claims (2)

[Claims] 1. A strip-shaped negative electrode made of lithium or a lithium alloy, and a strip-shaped positive plate in which a positive electrode mixture is held on a metal current collector are disposed via a separator made of a nonwoven fabric made of resin. A cylindrical nonaqueous electrolyte battery in which a spiral electrode group wound in the longitudinal direction of a positive electrode is housed in a bottomed cylindrical battery can, wherein a peripheral edge of the positive electrode forms a resin forming the separator. A cylindrical non-aqueous electrolyte battery characterized by being coated with a nonwoven fabric made of a non-aqueous electrolyte. 2. A strip-shaped negative electrode made of lithium or a lithium alloy and a strip-shaped positive plate in which a positive electrode mixture is held on a metal current collector are arranged via a separator, and wound in the longitudinal direction of the negative electrode and the positive electrode. A cylindrical non-aqueous electrolyte battery in which a spirally wound electrode plate group is accommodated in a bottomed cylindrical battery can, wherein a peripheral edge of the positive electrode is formed of polyethylene, polypropylene, polyamide 6, polyethylene terephthalate, polybutylene. A cylindrical nonaqueous electrolyte battery characterized by being coated with a nonwoven fabric using at least one resin selected from terephthalate and polyphenylene sulfide.