JP3632968B2 - Nonaqueous electrolyte secondary battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to improvement of safety.
[0002]
[Prior art]
The nonaqueous electrolyte secondary battery has a feature of being excellent in high energy density, and is suitable for a power source for an electronic device such as a mobile phone, and further for a power source for an electric vehicle.
[0003]
In particular, the electrolyte of the lithium ion secondary battery is not limited as long as it can dissolve a lithium salt, but an organic solvent having a large aprotic dielectric constant is particularly preferable. For example, propylene carbonate, ethylene carbonate, tetrahydrofuran, dimethyl carbonate, acetonitrile and the like. These solvents can be used alone or in combination.
[0004]
In addition, as the electrolyte, for example, lithium salts that generate stable anions such as lithium perchlorate, lithium borofluoride, lithium hexafluoroantimonate, lithium hexafluorophosphate, and the like are used.
[0005]
As the positive electrode active material, lithium composite metal oxides such as lithium manganese oxide (LiMn ₂ O ₄ ), lithium cobalt oxide (LiCoO ₂ ), and lithium nickel oxide (LiNiO ₂ ) can be used. As the negative electrode active material, a carbon material that can be doped or dedoped with lithium is used, and examples thereof include artificial graphite and natural graphite. As the separator, a polyolefin microporous film is generally used. Further, as the battery case and the lid for sealing the battery, stainless steel, aluminum, aluminum alloy, or iron plated with nickel is used.
[0006]
In general, a non-aqueous electrolyte secondary battery is manufactured as follows. That is, a binder is mixed with the above-described positive electrode active material and negative electrode active material, and each paste is applied to a metal foil, rolled, and cut into predetermined dimensions. Next, it winds in the shape of a spiral via separators, such as a separator, and the outermost periphery of the electrode body is stopped with a tape. Alternatively, the lithium metal or alloy rolled into a metal foil or the like and the metal foil coated with the positive electrode mixture paste, dried and rolled are wound in a spiral shape through a separator, and the outermost periphery of the electrode body is wound with tape. Stop. The resulting electrode body is housed in a battery case, injected with an electrolytic solution, and then sealed and fixed with a lid plate for assembly.
[0007]
[Problems to be solved by the invention]
When this type of battery is mounted on a device, the soldering iron or the like may inadvertently touch the battery case and the battery may be heated. In this type of battery, even if the cover plate at the top of the battery is heated somewhat, the electrode body and the cover plate are spaced apart, so that the electrode body is hardly damaged by heat. Moreover, since the insulating plate which insulates an electrode body and a battery case is comprised also in the battery case bottom part, an electrode body is not damaged.
[0008]
However, since the electrode case and the battery case are in direct contact with each other on the battery case side, the electrode body is damaged even when heated for a few seconds, and the separator and other separators are dissolved so that the positive electrode and the negative electrode Will be short-circuited.
[0009]
In addition to the case where the battery is mounted on a device, the above-described problem may occur when the battery is heated even during actual use.
[0010]
Therefore, the present invention provides a non-aqueous electrolyte secondary battery with excellent thermal durability that does not damage the electrode body even if heated on the side of the battery, and also reduces the defective rate generated in the manufacturing process. Objective.
[0011]
[Means for Solving the Problems]
The nonaqueous electrolyte secondary battery according to the present invention is characterized in that the outermost periphery of the spirally wound electrode body (2) is wound with a sheet (6) of polyphenylene sulfide resin, and the polyphenylene sulfide A tape (9) based on polyphenylene sulfide resin is used as an anti-winding adhesive tape for winding the resin sheet (6), and is perpendicular to the winding direction of the polyphenylene sulfide resin sheet (6). It is characterized in that the length of the direction is longer than that of the spiral electrode body, and these are combined.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, since the outermost periphery of the spiral electrode body is wound with the polyphenylene sulfide resin sheet, the electrode body is protected with the polyphenylene sulfide resin sheet even when the battery is heated, and the electrode body is damaged. Absent. In addition, when a tape based on a polyphenylene sulfide resin is used to stop the wound resin sheet, since the tape is not peeled off by heat even if heat is applied to the tape, the porphenylene sulfide wound around the electrode body The sheet will not loosen. The sheet may be fixed by applying an adhesive to the winding end portion of the sheet without using a tape.
[0013]
Since this polyphenylene sulfide resin has a heat-resistant temperature of 155 ° C. and a melting point of 287 ° C., heat is not directly transferred to the electrode body even when the battery is heated, as compared with polypropylene and polyethylene. Short circuit can be prevented well.
[0014]
In addition, by making the width of this resin sheet longer than the width of the electrode body, it goes without saying that the above-mentioned effect is obtained, but when the electrode body is housed in the battery case, the upper and lower portions of the electrode body are almost always damaged. At the same time, it plays the role of a guide to store it so that it will not be damaged. In addition, since the upper surface of the electrode body is not partially covered by this sheet only by winding the electrode body on the peripheral wall, the gas generated by the initial charging unique to the nonaqueous electrolyte battery can be reliably ensured from between the electrode plates. Since it can escape, the generation | occurrence | production of the lithium dendrite resulting from the gas accumulation between electrode plates can be prevented.
[0015]
Further, even when the electrolytic solution is injected after the electrode body is stored in the battery case, the upper surface of the electrode body is completely exposed, so that the injection can be performed uniformly without decreasing the injection speed.
[0016]
From the above, it is possible to provide a non-aqueous electrolyte secondary battery excellent in thermal durability and to reduce the defective rate generated in the manufacturing process.
[0017]
In the present invention, the present invention is not limited to a lithium ion secondary battery, and the structure thereof is a combination of a spiral electrode body of a positive electrode, a negative electrode, and a separator and a nonaqueous electrolytic solution, or a positive electrode, a negative electrode, and an organic solid electrolyte. A combination of a spiral electrode body and a non-aqueous electrolyte may be used.
[0018]
【Example】
[Example 1]
The present invention will be described in detail below based on preferred embodiments.
[0019]
1 is an external view of the positive electrode 3, and FIG. 2 is an external view of the negative electrode 4.
[0020]
The positive electrode body 3 was produced as follows. That is, a thickness of 0. On both surfaces of a 02 mm aluminum foil, 85 parts by weight of lithium cobaltate, 7 parts by weight of graphite as a conductive agent, and 8 parts by weight of polytetrafluoroethylene as a binder were applied as a paste, dried, and rolled. This was made into the dimension of width 54mm, thickness 0.188mm, and length 540mm, and the positive electrode lead 7 made from aluminum was attached to the edge part of this aluminum foil with the ultrasonic welding machine.
[0021]
The negative electrode body 4 was manufactured as follows. That is, a thickness of 0. 90 parts by weight of natural graphite capable of doping and undoping lithium and 10 parts by weight of polyvinylidene fluoride as a binder were mixed on both sides of a 01 mm copper foil, applied in a paste form, dried and rolled. This was made into the dimension of width 56mm, thickness 0.160mm, and length 490mm, and the negative electrode lead 8 made from nickel was attached to the edge part of this copper foil with the ultrasonic welding machine.
[0022]
The electrode body 2 was manufactured as follows. That is, after the positive electrode 3 and the negative electrode 4 were dried in vacuum at 120 ° C. for 10 hours, they were spirally wound through the separator 5 to obtain a width of 60 mm, a length of 60 mm, and a thickness of 0. The sheet was wound with a sheet 6 of 05 mm polyphenylene sulfide resin. And it wound around with the adhesive tape 9 which used polyphenylene sulfide resin as the base material, and produced the electrode body 2. FIG. The separator 5 was a polyethylene resin microporous membrane having a width of 58 mm and a thickness of 0.025 mm.
[0023]
FIG. 4 is a schematic cross-sectional view of a cylindrical lithium ion secondary battery 1 according to the present invention having a diameter of 18 mm, a height of 65 mm, and a battery capacity of 1000 mAh, assembled using the electrode body 2.
[0024]
The lithium ion secondary battery 1 was manufactured as follows. That is, the electrode body 2 was inserted into the battery case 10, and the positive electrode lead 7 and the negative electrode lead 8 were attached to the lid plate 11 and the bottom of the battery case 10 with a welding machine. And after pouring electrolyte solution, it sealed and fixed with the cover board 11 through the insulating packing 12. FIG. This is an example battery.
[0025]
As the electrolytic solution, a solution obtained by dissolving lithium hexafluorophosphate at a ratio of 1 mol / l in a mixed solvent of ethylene carbonate and diethyl carbonate was used.
[0026]
[Comparative Example 1]
The positive electrode 3 and the negative electrode 4 were spirally wound through a separator 5 and wound with a polyimide resin adhesive tape to assemble a battery in the same manner as in the example. However, it differs in that the outermost periphery is not wound with a polyphenylene sulfide resin sheet.
[0027]
This battery is referred to as a comparative battery.
[0028]
[Experiment]
Using 10 example batteries and 5 comparative example batteries, the tip of the soldering iron heated to 250 ° C. was brought into contact with the center of the battery case side for 10 seconds, and the state of breakage of the electrodes was examined. As for the damage status, the terminal voltage of the battery was measured to confirm the presence or absence of a short circuit. For safety reasons, the battery is 2. After discharging to 7V, it was used for the experiment.
[0029]
As a result, in the example battery, the terminal voltage of the battery was not changed by 10 before and after the soldering iron was brought into contact with the battery case. In the comparative example battery, after the soldering iron was brought into contact, all the battery terminal voltages were 5 0. It became 3V. When the battery was disassembled, the separator was melted by heat, and the positive electrode body and the negative electrode body were in contact with each other and short-circuited. In the present invention, the shape of the battery is not limited to a cylindrical shape, and may be a square shape or the like. In addition, the cross-sectional shape horizontal to the winding axis of the spiral electrode body is not limited to a circle, and may be an ellipse, an ellipse, a flat ellipse, or the like.
[0030]
【The invention's effect】
The nonaqueous electrolyte secondary battery according to the present invention is characterized in that the outermost periphery of the spirally wound electrode body (2) is wound with a sheet (6) of polyphenylene sulfide resin, and the polyphenylene sulfide A tape (9) based on polyphenylene sulfide resin is used as an anti-winding adhesive tape for winding the resin sheet (6), and is perpendicular to the winding direction of the polyphenylene sulfide resin sheet (6). It is characterized in that the length of the direction is longer than that of the spiral electrode body, and is characterized by combining these.
[0031]
According to the present invention, since the electrode body is protected by the polyphenylene sulfide resin sheet even when the battery case is heated, the electrode body is not damaged, and the battery can be prevented from being short-circuited. In addition, the winding of the wound polyphenylene sulfide resin sheet uses a tape based on polyphenylene sulfide resin, so that even if heat is applied to the tape, the tape is not melted or shrunk by heat. The porphenylene sulfide resin sheet that is wound is not loosened.
[0032]
And, when the electrode body is inserted into the battery case, the electrode body hits the battery case opening conventionally and the electrode body may be damaged. In the case of the present invention, the outermost periphery of the electrode body is a polyphenylene sulfide resin. Since it is protected by the sheet, the electrode body can be prevented from being damaged.
[0033]
In addition, in a battery of a power source for an electric vehicle or the like, for example, the capacity is 100 Ah class, the battery size is 67 mm in diameter, and the length is 410 mm. 5-0. 8mm. Therefore, when the electrode body is inserted into the battery case, depending on the battery, a large clearance occurs between the electrode body and the battery case, the electrode body moves in the battery case, and the electrode body may be damaged. By adjusting the winding length of the polyphenylene sulfide resin sheet, the clearance between the battery case and the electrode body can be eliminated, and the electrode body can be reliably fixed.
[0034]
From the above, the industrial value of the present invention is extremely large.
[0035]
[Explanation of drawings]
[0036]
FIG. 1 is an external view of a positive electrode body.
[0037]
FIG. 2 is an external view of a negative electrode body.
[0038]
FIG. 3 is an external view of an electrode body according to an example.
[0039]
FIG. 4 is a schematic cross-sectional view of a cylindrical lithium ion secondary battery according to one embodiment of the present invention.
[0040]
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylindrical lithium ion secondary battery 2 Electrode body 3 Positive electrode 4 Negative electrode 5 Separator 6 Polyphenylene sulfide resin sheet 7 Positive electrode lead 8 Negative electrode lead 9 Polyphenylene sulfide resin adhesive tape 10 Battery case 11 Cover plate 12 Insulation packing 13 Can upper insulating plate 14 Can Bottom insulation plate 15 Ultrasonic welding location

Claims (2)

A nonaqueous electrolyte secondary battery, characterized in that the outermost periphery of the spirally wound electrode body (2) is wound with a sheet (6) of polyphenylene sulfide resin. The nonaqueous electrolyte secondary battery according to claim 1, wherein a tape (9) based on a polyphenylene sulfide resin is used as an anti-winding adhesive tape for winding the polyphenylene sulfide resin sheet (6) .

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