JP3511966B2 - Cylindrical lithium-ion battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical lithium ion battery, and more particularly to a strip-shaped positive electrode having a positive electrode current collector coated with a positive electrode active material capable of releasing and storing lithium by charging and discharging, and a negative electrode current collector. An electrode winding group in which a strip-shaped negative electrode coated with a negative electrode active material capable of accommodating / releasing lithium by charging / discharging the body is wound around a shaft core through a strip-shaped separator through which lithium ions can pass. And a structure in which the electrode winding group is supported or fixed in the cylindrical battery container, the capacity is 30 Ah or more.
The present invention relates to a cylindrical lithium ion battery.

[0002]

2. Description of the Related Art Lithium ion secondary batteries have attracted attention as a power source for EVs (electric vehicles) because of their advantages of high output and high energy density. The lithium ion secondary battery can be classified into a cylindrical shape and a prismatic shape according to its shape.
Usually, inside a cylindrical battery, both the positive electrode and the negative electrode have a strip shape in which the active material is applied to the metal foil, and the separator is sandwiched so that the positive electrode and the negative electrode do not come into direct contact with each other, and the circumference of the cylindrical axis is surrounded. An electrode winding group having a spirally wound cross section is formed on. Then, the electrode winding group is housed in a cylindrical can or container that serves as a battery container, and after the electrolytic solution is injected, the electrode winding group is sealed and charged for the first time to impart a function as a battery.

Approximate capacity of 30 A suitable for use as a power source for EV
In a high-capacity, high-power lithium ion secondary battery of h or more, both the battery length and the battery diameter are large. When the above-mentioned strip-shaped electrode coated with the active material on the metal foil is thickened by increasing the coating amount of the active material to accommodate a large battery diameter, the active material layer peels off from the metal foil and falls off to form the electrode shape. Can no longer be maintained. Therefore, the diameter of the electrode winding group is increased by increasing the number of windings of the strip-shaped electrode.

On the other hand, in order to obtain a high output battery capable of discharging a large amount of current, for example, in the technique disclosed in Japanese Patent Laid-Open No. 9-92335, a large number of leads are taken out from an electrode and the leads are assembled to form a battery. Proposals have been made to construct a current collecting member that also serves as a terminal in a battery.

[0005]

However, in the electrode winding group having the winding structure as described above, stress is applied to the electrode winding group due to expansion / contraction of the volumes of the positive electrode active material and the negative electrode active material due to charging / discharging. As a result, the tight binding force of the electrode winding group decreases due to repeated charging / discharging, which leads to deterioration of battery characteristics such as charge / discharge capacity. In particular, in the electrode winding group in which the electrode winding group is long and the electrode winding group is wound many times, the deterioration of the battery characteristics becomes more remarkable. In order to prevent this, a device for maintaining a tight binding force of the whole electrode winding group by winding a tight binding member such as an adhesive fixing tape around the electrode winding group has been made.

However, in a cylindrical lithium-ion battery having a relatively large capacity and a high output, the size of the electrode winding group also becomes large, and when the battery falls into an abnormal state such as overcharge, the electrode winding group is discharged from the inside. The generated gas could not be exhausted promptly, and the battery container or the battery can could be cleaved.

In view of the above problems, it is an object of the present invention to provide a cylindrical lithium ion secondary battery having a high capacity and a high output, excellent safety, and a long life.

[0008]

In order to solve the above-mentioned problems, the present invention provides a strip-shaped positive electrode in which a positive electrode current collector is coated with a positive electrode active material capable of releasing and storing lithium by charging and discharging, and a negative electrode collector. Electrode winding in which a strip-shaped negative electrode coated with a negative electrode active material capable of accommodating and discharging lithium by charge and discharge is wound around an axis through a strip-shaped separator through which lithium ions can pass In a cylindrical lithium-ion battery having a capacity of 30 Ah or more, which has a structure in which the electrode winding group is supported or fixed in the cylindrical battery container, the inner diameter of the battery container is 1. 03 times or more, a gap is formed, tension on the outermost periphery of the electrode winding group strength between the battery container over the outer periphery of the electrode winding group
Of 2 × 10 ⁸ Pa or less is wound in three layers or more.

In the present invention, the electrode winding group is supported or fixed in the cylindrical battery container. The inner diameter of the battery container is 1.03 times or more the diameter of the electrode winding group, and the outer circumference of the electrode winding group
A gap is formed between the battery containers. Gas generated inside the electrode winding group when the battery is abnormal is guided to the upper part of the battery through this gap. If a binding member such as a tape that enhances the binding force is arranged around the electrode winding group of the cylindrical lithium-ion battery having such a structure, gas leakage will be deteriorated when the battery is abnormal. On the other hand, when a one-layer or two-layer separator is arranged on the outermost periphery of the electrode winding group without arranging the binding member, the electrode winding group has a reduced binding force, which reduces charge / discharge capacity and cycle life. Invite. Therefore, in the present invention,
By winding three or more layers of the separator around the outermost periphery of the electrode winding group without arranging the binding member, smooth gas release can be achieved at the time of battery abnormality, and reduction in charge / discharge capacity caused by reduction in binding force and It was decided to prevent the cycle life from decreasing. Also, the tensile strength of the separator is 2 × 10 ⁸ Pa
By doing the following, the power discharged to the outside of the battery when the battery is abnormal
The amount of pond contents is reduced and safety is improved. According to the present invention, in a cylindrical lithium ion battery having a capacity of 30 Ah or more, gas that is rapidly generated inside the electrode winding group when the battery is abnormal can be quickly guided to the upper portion of the battery, and at the same time, Since the binding force can be maintained, safety can be ensured in a high capacity / high output battery with a large size of the electrode winding group.
A long cycle life can be secured.

[0010] In this case, a lithium-manganese complex oxide in the positive electrode active material, and / or, if so use an amorphous carbon in the negative electrode active material, to moderate the behavior of the battery during battery abnormality Therefore, the safety can be further enhanced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described with reference to the drawings.
An embodiment applied to a V-mounting cylindrical lithium-ion battery will be described.

<Production of positive electrode plate> Lithium cobalt oxide (L
87 parts by weight of iCoO ₂ ) powder or lithium manganate (LiMn ₂ O ₄ ) powder that is a lithium manganese mixed oxide, and scaly graphite (average particle size: 20 μm) as a conductive agent.
8.7 parts by weight and 4.3 parts by weight of polyvinylidene fluoride (PVdF) as a binder were mixed, to which N-methyl-2-pyrrolidone (NMP) as a dispersion solvent was added and kneaded into a slurry. It was applied to both surfaces of an aluminum foil (positive electrode current collector) having a thickness of 20 μm. At this time, an uncoated portion having a width of 50 mm was left on one side edge in the lengthwise direction of the positive electrode plate. Then, it was dried, pressed and cut to obtain a strip-shaped positive electrode plate having a width of 300 mm, a predetermined length described later and a predetermined thickness of the positive electrode active material mixture application portion. Porosity of the positive electrode active material mixture layer is 35 ± 2%
And A notch was made in the uncoated portion of the positive electrode plate, and the remaining notch was used as a lead piece. In addition, adjacent lead pieces were spaced at 20 mm, and the width of the lead pieces was 10 mm.

<Production of Negative Electrode Plate> MCM manufactured by Osaka Gas Chemicals Co., Ltd. (hereinafter referred to as Osaka Gas Chemicals), which is a graphitic carbon capable of accommodating and releasing lithium by charging and discharging.
Carbtron P manufactured by Kureha Chemical Industry Co., Ltd. (hereinafter referred to as Kureha Chemical Co., Ltd.), which is B (trade name) powder or amorphous carbon.
(Brand name) To 92 parts by weight of powder, 8 parts by weight of polyvinylidene fluoride as a binder was added, and N-methyl-2-pyrrolidone as a dispersion solvent was added to the mixture, and the kneaded slurry was mixed with rolled copper having a thickness of 10 μm. It was applied to both sides of the foil (negative electrode current collector).
At this time, an uncoated portion having a width of 50 mm was left on one side edge in the lengthwise direction of the negative electrode plate. After that, dry, press, cut and width 3
A strip-shaped negative electrode plate having a length of 05 mm, which will be described later, and a predetermined thickness of the negative electrode active material coating portion was obtained. The porosities of the negative electrode active material layers were all 35 ± 2%. A notch was made in the uncoated portion of the negative electrode plate in the same manner as the positive electrode plate, and the remaining notch was used as a lead piece. In addition, the adjacent lead pieces are spaced by 20 mm,
The width of the lead piece was 10 mm.

<Production of Battery> The above-prepared strip-shaped positive electrode plate and negative electrode plate were wound with a polyethylene separator having a thickness of 40 μm and a width of 310 mm so as not to directly contact the both electrode plates. At this time, the separator on the outermost periphery of the wound group (electrode wound group) had three or more layers. Also, the lead pieces of the positive electrode plate and the negative electrode plate (see reference numeral 9 in FIG. 1).
Were located on opposite end surfaces of the winding group, respectively. The shaft center serving as the winding center is made of a resin having an electrically insulating property such as polypropylene in which glass fibers are dispersed and mixed as a filler, and has a diameter of 14 m.
m is a hollow tube having an inner diameter of 8 mm. The winding group diameter is the positive electrode plate,
The lengths of the negative electrode plate and the separator and the thicknesses of the positive electrode plate and the negative electrode plate were adjusted to 63 ± 0.5 mm. In addition, a strip-shaped positive electrode plate and a negative electrode plate are wound 40 times or more in the winding group.

As shown in FIG. 1, the lead pieces 9 led out from the positive electrode plate are deformed, and all of them are integrally projected from the periphery of the pole (the positive electrode external terminal 1) substantially on the extension line of the shaft core 11. After gathering and contacting with the peripheral surface of the collar portion 7, the lead piece 9 and the peripheral surface of the collar portion 7 are ultrasonically welded, and the lead piece 9 is connected and fixed to the peripheral surface of the collar portion 7. Further, the connection operation between the negative electrode external terminal 1 ′ and the lead piece 9 led out from the negative electrode plate was performed in the same manner as the connection operation between the positive electrode external terminal 1 and the lead piece 9 led out from the positive electrode plate.

After that, an insulating coating 8 was applied to the entire circumference of the flange 7 of the positive electrode external terminal 1 and the negative electrode external terminal 1 '. The insulating coating 8 also applied to the entire outer peripheral surface of the winding group 6. For the insulating coating 8, a pressure sensitive adhesive tape was used in which the base material was polypropylene and one side of which was coated with a pressure sensitive adhesive made of hexamethacrylate. This adhesive tape was wound at least once over the circumference of the collar 7 and the outer circumference of the winding group 6 to form the insulating coating 8. The battery container 5 has an outer diameter of 67 mm and an inner diameter of 66 mm. The inner diameter 66 mm of the battery container 5 of the present embodiment is about 1.05 times the average diameter 63 mm of the winding group 6.

The thickness of the portion made of alumina that contacts the back surface of the disk-shaped battery lid 4 is 2 mm, the inner diameter is 16 mm, and the outer diameter is 25.
As shown in FIG. 1, the second ceramic washer 3 ′ having a size of 2 mm was fitted in the pole column whose tip constitutes the positive electrode external terminal 1 and the pole column whose tip constituted the negative electrode external terminal 1 ′.
Also made of alumina, thickness 2mm, inner diameter 16mm, outer diameter 2
The 8 mm flat plate-shaped first ceramic washer 3 was placed on the battery lid 4, and the positive electrode external terminal 1 and the negative electrode external terminal 1 ′ were respectively passed through the first ceramic washer 3. After that, the peripheral end surface of the battery lid 4 was fitted into the opening of the battery container 5, and the entire contact portions of both were laser-welded. At this time, the positive electrode external terminal 1,
The negative electrode external terminal 1 ′ penetrates a hole formed at the center of the battery lid 4 and projects to the outside of the battery lid 4. Then, as shown in FIG. 1, the first ceramic washer 3 and the metal washer 14 that was smoother than the bottom surface of the metal nut 2 were fitted in this order to the positive electrode external terminal 1 and the negative electrode external terminal 1 ′, respectively. The battery lid 4 is provided with a cleaving valve 10 that cleaves in response to an increase in the internal pressure of the battery. The cleavage pressure of the cleavage valve 10 was 1.3 × 10 ^{6 to} 1.8 × 10 ⁶ Pa.

Next, the nut 2 is screwed to the positive electrode external terminal 1 and the negative electrode external terminal 1 ', respectively, and the battery lid 4 is fitted with the second ceramic washer 3', the first ceramic washer 3 and the metal washer 14 together. It was fixed by tightening between the portion 7 and the nut 2. The tightening torque value at this time is 5N
・ M. The metal washer 14 did not rotate until the tightening work was completed. In this state, the power generation element inside the battery container 5 is shielded from the outside air by the compression of the rubber (EPDM) O-ring 16 interposed between the back surface of the battery lid 4 and the collar portion 7.

After that, a predetermined amount of electrolytic solution is injected into the battery container 5 through the liquid injection port 15 provided in the battery lid 4, and then the liquid injection port 1
Cylindrical lithium ion battery 20 by sealing 5
Was completed.

The electrolytic solution contains ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:
Lithium hexafluorophosphate (LiP
A solution obtained by dissolving 1 mol / liter of F ₆ ) was used. It should be noted that the cylindrical lithium ion battery 20 is not provided with a current cutoff mechanism that cuts off current in accordance with an increase in the internal pressure of the battery container 5.

Next, an example of the cylindrical lithium ion battery 20 manufactured according to this embodiment will be described. First, the positive electrode plate and the negative electrode plate of the example were manufactured as follows.

<Positive Electrode Plate> [Positive Electrode Plate C-1] A positive electrode active material is made of cell seed C-10 (trade name) manufactured by Nippon Chemical Industry Co., Ltd. A positive electrode plate including an electric body having an electrode thickness of 195 μm and a length of 636 cm was produced (hereinafter, this positive electrode plate is referred to as positive electrode plate C-1). The bulk density of the positive electrode active material mixture layer at this time is 2.
It was set to 77 g / cm ³ . [Cathode C-2] Nihon Kagaku Cell Seed C is used as the cathode active material.
Using -10 as a lithium cobalt oxide, a positive electrode plate including a positive electrode current collector and having an electrode thickness of 199 μm and a length of 629 cm was produced (hereinafter, this positive electrode plate is referred to as positive electrode plate C-2). The bulk density of the positive electrode active material mixture layer at this time is 2.
It was set to 77 g / cm ³ . [Positive electrode plate M-1] The positive electrode active material is lithium manganate manufactured by Mitsui Metal Co., Ltd. (hereinafter referred to as Mitsui Metal Co., Ltd.),
Electrode thickness including positive electrode current collector 240 μm, length 620c
m positive electrode plate was produced (hereinafter, this positive electrode plate is referred to as positive electrode plate M-
1 ). The bulk density of the positive electrode active material mixture layer at this time was 2.61 g / cm ³ . [Positive electrode plate M-2] The positive electrode active material is lithium manganate manufactured by Mitsui Metals, and the electrode thickness including the positive electrode current collector is 243 μm.
A positive electrode plate having a length of m and a length of 618 cm was produced (hereinafter, this positive electrode plate is referred to as a positive electrode plate M-2). The bulk density of the positive electrode active material mixture layer at this time was 2.61 g / cm ³ .

<Negative Electrode Plate> [Negative Electrode Plate B-1] MCMB manufactured by Osaka Gas Chemicals was used as the graphitic carbon, and the electrode thickness 17 including the negative electrode current collector was used.
A negative electrode plate having a size of 3 μm and a length of 654 cm was produced (hereinafter, this negative electrode plate is referred to as negative electrode plate B-1). The bulk density of the negative electrode active material mixture layer at this time was 1.35 g / cm ³ . [Negative Electrode Plate B-2] MCMB manufactured by Osaka Gas Chemicals was used as the graphitic carbon, and the electrode thickness 14 including the negative electrode current collector was 14
A negative electrode plate having a size of 1 μm and a length of 638 cm was produced (hereinafter, this negative electrode plate is referred to as negative electrode plate B-2). The bulk density of the negative electrode active material mixture layer at this time was 1.35 g / cm ³ . [Negative Electrode Plate P-1] As amorphous carbon, a carbon nanotube P manufactured by Kureha Chemical was used, and an electrode thickness including a negative electrode current collector was 175 μm.
A negative electrode plate having a length of m and a length of 647 cm was produced (hereinafter, this negative electrode plate is referred to as negative electrode plate P-1). The bulk density of the negative electrode active material mixture layer at this time was 0.98 g / cm ³ . [Negative Electrode Plate P-2] Carbotron P manufactured by Kureha Chemical Co., Ltd. was used as the amorphous carbon, and the electrode thickness including the negative electrode current collector was 140 μm.
A negative electrode plate having a length of m and a length of 636 cm was produced (hereinafter, this negative electrode plate is referred to as negative electrode plate P-2). The bulk density of the negative electrode active material mixture layer at this time was 0.98 g / cm ³ .

<Structure> The battery specifications of each embodiment will be described below. In each of the examples, an acrylic adhesive tape was used to fix the shaft core 11 and the separator.

Example 1 As shown in Table 1 below, a positive electrode plate M-2 and a negative electrode plate P-2 were combined to obtain a tensile strength of 1.8 × 10 ⁸ Pa (N / m ² ) in the longitudinal direction. Using a strip-shaped separator, as shown in FIG. 2, the positive electrode plate 31 and the negative electrode plate 3
A battery 20 was manufactured by winding the separator 33 between the first and second electrodes via a separator 33 to form the outermost separator 33 of the winding group 6 in three layers.

[0026]

[Table 1]

Example 2 As shown in Table 1, the positive electrode plate M
-2, the negative electrode plate P-2 is combined, a strip-shaped separator having a tensile strength of 1.8 × 10 ⁸ Pa in the length direction is used, and as shown in FIG. 3, a separator is provided between the positive electrode plate 31 and the negative electrode plate 32. The battery 20 was wound with 33 layers, and the outermost separator 33 of the winding group 6 was made into five layers to prepare a battery 20. (Example 3) As shown in Table 1, a positive electrode plate C-1 and a negative electrode plate
A battery 20 was produced in the same manner as in Example 1 described above except that B-1 was combined. (Example 4) As shown in Table 1, a battery 20 was produced in the same manner as in Example 1 except that the positive electrode plate M-1 and the negative electrode plate B-2 were combined. (Example 5) As shown in Table 1, a battery 20 was produced in the same manner as in Example 1 except that the positive electrode plate C-2 and the negative electrode plate P-1 were combined. (Example 6) As shown in Table 1, a battery 20 was produced in the same manner as in Example 1 except that the positive electrode plate C-1 and the negative electrode plate B-1 were combined. (Example 7) As shown in Table 1, a positive electrode plate M-2 and a negative electrode plate P-2 were combined, and the tensile strength in the length direction was 2.2 ×.
Using a strip-shaped separator of 10 ⁸ Pa, as shown in FIG. 2, the positive electrode plate 31 and the negative electrode plate 32 are wound with a separator 33 interposed therebetween, and the outermost separator 33 of the winding group 6 is set to 3 pieces.
A layered battery 20 was prepared.

<Structure of Comparative Example> Further, in order to compare with the above example, a cylindrical lithium ion battery of the following comparative example was also produced.

Comparative Example 1 As shown in Table 1, the positive electrode plate M
-2, the negative electrode plate P-2 is combined, a strip-shaped separator having a tensile strength of 1.8 × 10 ⁸ Pa in the length direction is used, and as shown in FIG. 4, a separator is provided between the positive electrode plate 31 and the negative electrode plate 32. It winds through 33, the separator 33 of the outermost periphery of the winding group 6 is made into one layer, and further 50 micrometers in thickness is provided in the outer periphery.
A battery in which a polypropylene adhesive tape 34 having a width of 280 mm was wound was produced. The adhesive of the tape is an acrylic adhesive. (Comparative Example 2) As shown in Table 1, a positive electrode plate M-2 and a negative electrode plate P-2 were combined and the tensile strength in the length direction was 1.8 ×.
Using a strip-shaped separator of 10 ⁸ Pa, as shown in FIG. 5, the separator 33 is wound between the positive electrode plate 31 and the negative electrode plate 32 with the separator 33 interposed therebetween.
A layered battery was prepared. (Comparative Example 3) As shown in Table 1, a positive electrode plate M-2 and a negative electrode plate P-2 were combined and the tensile strength in the length direction was 1.8 ×.
Using a strip-shaped separator of 10 ⁸ Pa, as shown in FIG. 6, the positive electrode plate 31 and the negative electrode plate 32 are wound with a separator 33 in between, and the outermost peripheral separator 33 of the winding group 6 is set to 1
A layered battery was prepared.

<Test / Evaluation> [Test] Next, with respect to each of the batteries of Examples and Comparative Examples produced as described above, a constant voltage of 4.2 V at 25 ± 3 ° C.
After charging with a current limit (upper limit) of 30 A for 5 hours, the battery was discharged under the conditions of a constant current of 30 A and an end voltage of 2.5 V, and the initial discharge capacity was measured.

Thereafter, the battery temperature is heated to 60 ± 3 ° C., and at an environmental temperature of 60 ± 3 ° C., a constant voltage of 4.2 V, a current limit (upper limit) 60 A, charging for 3 hours, 0.5 hour After rest, discharge under the condition of 60A constant current, final voltage 2.5V,
Repeated charging / discharging cycle of 0.5 hour, 200
The discharge capacity at the time of the cycle was measured, and the discharge capacity retention ratio with respect to the initial discharge capacity was obtained.

For each of the batteries produced, 25 ± 3
Percentage of battery weight before overcharging by measuring the battery weight after the so-called overcharge test, in which the battery is continuously charged at a constant current of 30 A at ° C, and after cleaving the cleavage valve 10 and blowing out internal gas. I asked. If the phenomenon at the time of overcharging is not gentle, the contents (for example, active material powder etc.) are also ejected to the outside of the battery at the same time as the gas, so the weight of the battery after the occurrence of the phenomenon becomes light. Furthermore, the appearance of the battery after the occurrence of the phenomenon was visually observed.

[Test Results] Table 2 below shows the test results of these series of tests.

[0034]

[Table 2]

[Evaluation] As shown in Tables 1 and 2, as in the batteries of Comparative Examples 2 and 3, the outermost peripheral separator 3 was used.
It can be seen that in a battery in which 3 is less than 3 layers, the discharge capacity retention ratio, in other words, the cycle life is greatly reduced, as compared with each battery of Examples having 3 or more layers. Further, in the battery of Comparative Example 1 in which the separator 33 was one layer and the adhesive tape was wrapped around the outer periphery thereof, the discharge capacity retention ratio was comparable to the batteries of the Examples, but as a result of the overcharge test, the battery weight was 57%. It can be seen that the safety is lowered because of the large decrease and the swelling of the container on the appearance of the battery. Therefore, in order to satisfy both cycle life and safety, it is understood that the outermost peripheral separator 33 of the winding group 6 needs to have three or more layers.

When the tensile strength of the separator 33 exceeds 2 × 10 ⁸ Pa as in the battery of Example 7, the discharge capacity retention ratio is comparable to that of the other Examples, but the battery after overcharging is not affected. A slight decrease in weight was observed. Therefore,
It can be seen that the tensile strength of the separator 33 is preferably 2 × 10 ⁸ Pa or less in order to further enhance safety.

Further, among the batteries of the examples, the battery using lithium manganate was more preferable than the battery using lithium cobalt oxide as the positive electrode active material, and the battery using graphite carbon as the negative electrode active material. It can be seen that the battery using amorphous carbon has a smaller decrease in battery weight after overcharging (the battery behaves more gently when the battery is abnormal) and is more safe than the battery using amorphous carbon. The batteries of Examples 1 and 2 in which lithium manganate was used as the positive electrode active material and amorphous carbon was used as the negative electrode active material were
It can be seen that the battery weight decreases the least after overcharging, and the safety is excellent.

As described above, the cylindrical lithium-ion battery 20 of this embodiment has high capacity and high output,
Since it is excellent in safety and has a long life, it is particularly suitable as a power source for EV.

In the present embodiment, the large-sized secondary battery for EV mounting is exemplified, but it goes without saying that the battery is not limited in application and size as long as the battery has a substantial capacity of 30 Ah or more. . Further, the present invention can be applied to a cylindrical lithium ion battery having a structure in which a battery upper lid is closed by caulking in a bottomed cylindrical container (can).

Further, in the present embodiment, the cylindrical lithium ion battery having no current cutoff mechanism has been exemplified.
The present invention may be applied to a battery provided with a current interruption mechanism. By doing so, the internal pressure reduction mechanism such as the mechanical decompression valve 10 operates even if the electric current interruption mechanism does not operate at the time of an abnormality such as a vehicle collision accident, thus ensuring higher safety of the on-vehicle battery. To be done.

Further, in the present embodiment, the insulating coating 8 uses the adhesive tape in which the base material is polypropylene and the adhesive agent of hexamethacrylate is applied to one surface thereof.
The present invention is not limited to this. For example, a base material is a polyolefin such as polyimide or polyethylene, and one side or both sides thereof is coated with an acrylic pressure sensitive adhesive such as hexamethacrylate or butyl acrylate, or a pressure sensitive adhesive is applied. A tape or the like made of a non-polyolefin or polyimide can be preferably used.

Further, in this embodiment, lithium cobalt oxide or lithium manganate is used for the positive electrode of the lithium ion battery, graphitic carbon or amorphous carbon is used for the negative electrode, and the volume ratio of ethylene carbonate, dimethyl carbonate, and diethyl carbonate is used for the electrolytic solution. A mixture of 1: 1: 1 lithium hexafluorophosphate dissolved in 1 mol / liter was used.
The method for producing the battery of the present invention is not particularly limited, and any of the commonly used binders, negative electrode active materials, and non-aqueous electrolytes can be used. In order to ensure the safety in a high-capacity, high-output battery for EV applications, it is necessary to use lithium manganese compound oxide rather than lithium-cobalt compound oxide or lithium-nickel compound oxide as the positive electrode active material. It is more preferable to use lithium manganate, which is a substance.

Although polyvinylidene fluoride is used as the binder in this embodiment, the electrode active material binder for lithium ion batteries may be made of Teflon, polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene / Butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latex,
Acrylonitrile, vinyl fluoride, vinylidene fluoride,
Polymers such as propylene fluoride and chloroprene fluoride and mixtures thereof may be used.

Further, as a positive electrode active material for a lithium secondary battery other than those shown in this embodiment, a lithium manganese compound oxide is a material into which lithium can be inserted / released and in which a sufficient amount of lithium has been inserted in advance. However, lithium manganate having a spinel structure or a material in which a part of manganese or lithium in the crystal is replaced or doped with an element other than these may be used. Further, even when an active material in which the atomic ratio of lithium to manganese deviates from the stoichiometric ratio is used, the same effect as this embodiment can be obtained.

Furthermore, the use of the present invention is not limited even if a negative electrode active material for lithium ion batteries other than those shown in this embodiment is used. For example, natural graphite, various artificial graphite materials, carbonaceous materials such as coke, and the like may be used, and the particle shape thereof is not particularly limited, such as scaly, spherical, fibrous, and lumpy. .

As the electrolytic solution, a general lithium salt may be used as an electrolyte and an electrolytic solution obtained by dissolving this in an organic solvent may be used. The lithium salt and the organic solvent are not particularly limited. For example, as the electrolyte, LiCl
O ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB
_{(C 6 H 5) 4,} CH 3 SO 3 Li, CF 3 SO 3 Li
Etc. and mixtures thereof can be used.

As the non-aqueous electrolyte organic solvent other than this embodiment, propylene carbonate, ethylene carbonate, ethylmethyl carbonate, vinylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone is used. , Tetrahydrofuran,
1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile, etc. or these 2
A mixed solvent of more than one kind can be used, and the mixing ratio is not limited.

[0048]

As described above, according to the present invention,
For cylindrical lithium-ion batteries with a capacity of 30 Ah or more
The gas generated suddenly inside the electrode winding group when the battery is abnormal can be quickly guided from the gap formed on the outer periphery of the electrode winding group to the upper direction of the battery, and the tight binding force of the electrode winding group can be provided. it is possible to hold the at large high capacity, high output battery sizes electrode winding group, the co-if it is possible to ensure safety, it is possible to ensure a long cycle life, the effect of Obtainable.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an EV mounting cylindrical lithium-ion battery according to an embodiment to which the present invention is applicable.

FIG. 2 is a cross-sectional view of a wound group of a cylindrical lithium ion battery of an example, showing a structure in which three layers of separators are wound around the outermost circumference of the wound group.

FIG. 3 is a cross-sectional view of a winding group of a cylindrical lithium-ion battery of another example, in which the separator has 5 separators at the outermost periphery of the winding group.
It is a figure which shows the structure wound by layers.

FIG. 4 is a cross-sectional view of a winding group of a cylindrical lithium ion battery of a comparative example, showing a structure in which one layer of a separator is wound around the outermost circumference of the winding group and further a tape is wound around the winding group. is there.

FIG. 5 is a cross-sectional view of a winding group of a cylindrical lithium-ion battery of another comparative example, in which two separators are provided on the outermost periphery of the winding group.
It is a figure which shows the structure wound by layers.

FIG. 6 is a cross-sectional view of a winding group of a cylindrical lithium-ion battery of another comparative example, in which a separator is placed at the outermost periphery of the winding group.
It is a figure which shows the structure wound by layers.

[Explanation of symbols]

5 battery container 6 winding group (electrode winding group) 7 collar part 9 lead pieces 10 Cleavage valve 11 shaft core 20 Cylindrical lithium-ion battery 31 Positive plate 32 negative plate 33 separator

─────────────────────────────────────────────────── ─── Continuation of front page (72) Kensuke Hironaka 2-8-7 Nihonbashihonmachi, Chuo-ku, Tokyo Shin-Kobe Electric Machinery Co., Ltd. (56) Reference JP-A-11-224693 (JP, A) JP-A 5-74495 (JP, A) JP 9-266010 (JP, A) JP 2000-306324 (JP, A) JP 2001-35537 (JP, A) JP 9-283178 (JP, A) JP-A-11-260419 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 10/40 H01M 2/14-2/18 H01M 4/02-4/04 H01M 4 / 38-4/62

Claims (3)

(57) [Claims] 1. A strip-shaped positive electrode in which a positive electrode current collector is coated with a positive electrode active material capable of releasing / accommodating lithium by charging / discharging, and a negative electrode active material capable of accommodating / releasing lithium in a negative electrode current collector by charging / discharging. The strip-shaped negative electrode coated with, comprises an electrode winding group wound around the axis through a strip-shaped separator capable of passing lithium ions, the electrode winding group in the cylindrical battery container In a cylindrical lithium ion battery having a supported or fixed structure and a capacity of 30 Ah or more, the inner diameter of the battery container is 1.03 times or more the diameter of the electrode winding group, and A gap is formed between the battery container and the electrode winding group, and the tensile strength is
A cylindrical lithium-ion battery, characterized in that the separator of 2 × 10 ⁸ Pa or less is wound in three layers or more. 2. The cylindrical lithium ion battery according to claim 1, wherein the positive electrode active material is a lithium manganese composite oxide. Wherein the negative electrode active material, a cylindrical lithium ion battery according to claim 1 or claim 2, wherein the amorphous carbon.