JPH11273743A - Cylindrical nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance energy density of a battery without decreasing a rate of conforming article in insertion of a spirally wound electrode body into a cylindrical battery can. SOLUTION: In a cylindrical nonaqueous electrolyte secondary battery prepared by housing a spirally wound electrode body 15 formed by spirally winding a belt-like negative electrode 1 and a belt-like positive electrode 2 nipping a separator 3 and fixing the winding end part with an adhesive tape 20 in a cylindrical battery can 5 together with a nonaqueous electrolyte, a part (20a) of the adhesive tape 20 is bent and bonded to a negative lead taking out side end part 15a of the spirally wound electrode body 15. When the width of the bent part of the adhesive tape is represented by D, the length is represented by L, the outer diameter of the spirally wound electrode body is represented by R, and the inner diameter of the battery can is represented by C, formulas D<2> /(C<2> -R<2> )<=3 and 0<L/R<=1 are preferable to be satisfied at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spirally wound electrode body comprising a strip-shaped negative electrode and a strip-shaped positive electrode wound spirally with a separator interposed therebetween, and the end of which is fixed with an adhesive tape. And a cylindrical nonaqueous electrolyte secondary battery housed in a cylindrical battery can.

[0002]

2. Description of the Related Art In recent years, remarkable progress in electronic technology has realized reduction in size and weight of electronic devices. with this,
There is a strong demand for batteries as mobile power sources to be smaller, lighter, and have higher energy density.

In response to such demands, conventional lead-acid batteries,
Instead of an aqueous secondary battery such as a nickel-cadmium battery, use a carbon-based material capable of reversibly doping and undoping lithium ions in the negative electrode active material, and use lithium composite oxide as the positive electrode active material. BACKGROUND ART An ionic nonaqueous electrolyte secondary battery has been put to practical use as a secondary battery that exhibits good charge / discharge cycle characteristics at a high energy density.

[0004] Such a non-aqueous electrolyte secondary battery is used as a power source for electronic devices such as notebook personal computers, camcorders, and portable audio devices that consume relatively large power. For this reason, the structure of the non-aqueous electrolyte secondary battery is a spiral electrode body formed by spirally winding a strip-shaped negative electrode and a strip-shaped positive electrode through a separator in order to increase the electrode surface area and improve output characteristics. 15 (see FIG. 4) is housed in a cylindrical battery can. Here, the spiral electrode body 15
A negative electrode lead 11 is provided on the outer peripheral side, and a positive electrode lead 12 is provided on the inner peripheral side.

In such a spiral type electrode body for a cylindrical non-aqueous electrolyte secondary battery, as shown in FIG. 4, the winding end portion is fixed with an adhesive tape 20 so that the electrode body is not loosened. ing. In this case, the adhesive tape 20 is fixed so that the adhesive tape 20 does not protrude to the side end 15a of the spiral electrode body 15.

In the cylindrical non-aqueous electrolyte secondary battery, the spirally wound electrode body 15 fixed as described above is inserted into a cylindrical battery can (not shown) from the side where the negative electrode lead is taken out. Manufactured by injection. In this case, when inserting the spiral electrode body 15 into the cylindrical battery can, in order to prevent insertion failure due to various factors and reduce the non-defective rate of the nonaqueous electrolyte secondary battery, the spiral electrode body 15 is used. A clearance is provided between the battery case 15 and the cylindrical battery can. That is,
The outer diameter of the spiral electrode body 15 is made slightly smaller than the inner diameter of the cylindrical battery can.

[0007]

However, if the above-mentioned clearance is increased in order to increase the yield of non-aqueous electrolyte secondary batteries, the outer diameter of the spiral electrode body 15 must be relatively small. However, as a result, a space that does not contribute to the battery reaction in the cylindrical battery can becomes large, and there is a problem that the energy density of the nonaqueous electrolyte secondary battery decreases.

As described above, when the spiral electrode body is inserted into the cylindrical battery can, it is necessary to increase the above-described clearance to improve the yield rate and to improve the energy density of the battery. It is the present situation that it is wanting.

An object of the present invention is to solve the problems of the prior art described above, and it is possible to reduce the non-defective rate when a spiral electrode body is inserted into a cylindrical battery can without lowering the energy density of the battery. The purpose is to improve.

[0010]

The inventor of the present invention has found that, in a spirally wound electrode body in which insertion into a cylindrical battery can fails, the adhesive tape is partially peeled off, and the outermost electrodes and separators are separated from that part. It turned out that the cause was friction or collision between the inner wall of the battery can and the adhesive tape or between the inner wall of the battery can and the outermost periphery of the spiral electrode body. Then, based on the knowledge, the present inventor bends a part of the adhesive tape that fixes the winding end portion of the spiral electrode body to the negative electrode lead extraction side end of the spiral electrode body, and adheres it.
The present inventors have found that the peeling of the pressure-sensitive adhesive tape at the time of inserting the spiral electrode body into the cylindrical battery can can be prevented, and the above-mentioned object can be achieved. Thus, the present invention has been completed.

That is, the present invention provides a spirally wound electrode body in which a strip-shaped negative electrode and a strip-shaped positive electrode are spirally wound with a separator interposed therebetween, and the end of which is fixed using an adhesive tape. A cylindrical non-aqueous electrolyte secondary battery housed in a type battery can, characterized in that a part of the adhesive tape is bent and adhered to the end of the spiral electrode body on the negative electrode lead extraction side. Provided is a non-aqueous electrolyte secondary battery.

In this case, the width of the bent portion of the adhesive tape which is bent and adhered to the end of the spiral electrode body on the negative electrode lead take-out side is D, the length is L, and the outer diameter of the spiral electrode body Where R is the internal diameter of the cylindrical battery can and C is the following equation (1) and (2)

[0013]

D ² / (C ² −R ² ) ≦ 3 (1) It is preferable that 0 <L / R ≦ 1 (2) be satisfied at the same time.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

FIG. 1 is a schematic sectional view of a cylindrical non-aqueous electrolyte secondary battery of the present invention.

In this battery, a band-shaped negative electrode 1 formed by applying a negative electrode mixture to both surfaces of a negative electrode current collector 9 and a band-shaped positive electrode 2 formed by applying a positive electrode mixture to both surfaces of a positive electrode current collector 10 are separated by a separator. The spirally wound electrode body 15 formed by winding through the coil 3 is accommodated in the cylindrical battery can 5 together with the electrolytic solution, and the spirally wound electrode body 15 is formed.
Has a structure in which insulating plates 4 are arranged on both upper and lower surfaces. Further, a negative electrode lead 11 for electrically connecting the band-shaped negative electrode 1 and the cylindrical battery can 5 is led out of the negative electrode current collector 9 and welded to the cylindrical battery can 5, and the band-shaped positive electrode 2 and the battery A positive electrode lead 12 for electrically connecting to the lid 7 is led out of the positive electrode current collector 10 and is welded to the safety valve 8.
Furthermore, by caulking the cylindrical battery can 5 through the insulating sealing gasket 6, the battery lid 7 and the safety valve 8 having a current cutoff mechanism are fixed, and the airtightness inside the battery is maintained.

In this non-aqueous electrolyte secondary battery, as in the prior art, the end of the spiral electrode body 15 is wound with the adhesive tape 2.
Although it is fixed at 0, a part thereof is bent to the negative electrode lead take-out end 15a (see FIG. 2) of the spiral electrode body 15, and the bent portion 20a is adhered.

As described above, the adhesive tape 20 is bent to the negative electrode lead take-out side end 15a of the spiral electrode body 15,
By bonding the bent portion 20a, contact between the tip of the adhesive tape 20 and the inner wall of the cylindrical battery can 5 is avoided, and as a result, the adhesive tape 20 is peeled off by friction with the inner wall of the cylindrical battery can 5 Is less likely to occur, and the operation of inserting the spiral electrode body 15 into the cylindrical battery can 5 becomes smooth. Therefore, even when the clearance between the spiral electrode body 15 and the cylindrical battery can 5 is minimized in order to increase the energy density of the battery, it is possible to prevent the adhesive tape 20 from being partially peeled off. .

In this case, when the wide adhesive tape 20 is used, the adhesive area between the adhesive tape 20 and the spiral electrode body 15 is increased, and the fixing strength capable of resisting the loosening of the spiral electrode body 15 is maintained. However, if the width D of the bent portion of the adhesive tape 20 is too large, wrinkles of the adhesive tape 20 caused by the bending become large, and the spiral electrode body 15
It is difficult to secure a sufficient clearance between the battery case 5 and the cylindrical battery can 5. Therefore, as shown in FIGS. 1 and 2, the outer diameter of the spiral electrode body 15 is R, and the inner diameter of the cylindrical battery can 5 is C.
When the width of the bent portion 20a of the adhesive tape 20 is D and the length is L, the relationship is experimentally expressed by the following equations (1) and (2).

[0020]

Equation 3] ^{D 2 / (C 2 -R 2} ) ≦ 3 (1) 0 < it is preferable to satisfy L / R ≦ 1 and (2) simultaneously.

The decrease in the clearance due to the wrinkles of the adhesive tape 20 is caused by the bent portion 2 of the adhesive tape 20.
It depends not only on the width D of Oa but also on the thickness of the adhesive tape 20. Therefore, if the thickness of the adhesive tape 20 is reduced, the decrease in clearance can be reduced, the outer diameter R of the spiral electrode 15 can be increased while maintaining a high yield rate, and the battery capacity can be increased. Also, by using a tape having a lower bending strength as the adhesive tape 20, the wrinkles generated in the adhesive tape 20 are folded into the insertion and holding of the spiral electrode body 15 into the cylindrical battery can 5, thereby reducing the clearance. Can be reduced, and the battery capacity can be increased.

Adhesive tape 20 usable in the present invention
Can be a tape in which an adhesive is applied on a supporting substrate, and the supporting substrate and the adhesive have sufficient physical and chemical stability to an organic solvent used for an electrolytic solution. Further, one having sufficient adhesive strength to the separator 3 located on the outermost periphery of the spiral electrode body 15 is used. For example, examples of the support substrate include a polyethylene tape substrate, a polypropylene tape substrate, a polyvinyl chloride tape substrate, a polyester tape substrate, a polyimide tape substrate, and a fluororesin tape substrate. Further, as the pressure-sensitive adhesive, a silicon-based pressure-sensitive adhesive can be preferably mentioned.

The shape of the adhesive tape 20 is generally rectangular as shown in FIG. 2, but as shown in FIG.
A cut may be made along a line that bisects the tape width, for example, to form two bent portions 20a. In this case, each bent portion 20a
To the end 15a of the spiral electrode body 15 on the side where the negative electrode lead is taken out.
May be bent toward the center of the sheet and bonded.

The cylindrical non-aqueous electrolyte secondary battery of the present invention is different from the conventional spiral-type electrode body except that the winding end of the spiral-type electrode body is fixed with an adhesive tape as described above. The same configuration as the non-aqueous electrolyte secondary battery can be provided.

For example, the negative electrode active material of the cylindrical non-aqueous electrolyte secondary battery of the present invention includes an alkali metal, an alkali metal alloy, and a carbon which can be doped / dedoped with an alkali metal ion such as lithium during charge / discharge reaction. Materials, organic polymer materials, metal oxides, metal sulfides, transition metal nitrides containing lithium, and the like can be used. For example, lithium, lithium-aluminum alloy, graphite, pyrolytic carbons, cokes (petroleum coke, pitch coke, lime coke, etc.), carbon black (acetylene black, etc.), glassy carbon, fired organic polymer material (organic Polymer material fired at an appropriate temperature of 500 ° C. or more in an inert gas stream or vacuum), carbon fiber, polyacetylene, polyparaphenylene, MoO ₂ , TiS ₂ , LiC
o _0.5 N or the like can be used. In addition, these materials can be used alone or as a composite or a mixture.

Particularly preferred materials for the negative electrode active material are those having a (002) plane spacing of at least 3.7 ° and a true specific gravity of 1.0.
A carbonaceous material which is less than 70 g / cm ³ and does not have an exothermic peak at 700 ° C. or more in differential thermal analysis in an air stream.

Examples of such a carbonaceous material include a carbonaceous material obtained by carbonizing an organic material by a method such as firing. As the organic material as a starting material for carbonization, furfuryl alcohol or furfural made of a homopolymer or copolymer of furfural is preferable. Specifically, a copolymer consisting of furfural and phenol, a copolymer consisting of furfuryl alcohol and dimethylol urea, a copolymer consisting of furfuryl alcohol and formaldehyde, a copolymer consisting of furfuryl alcohol and furfural, and furfural and ketones And the like.

As a negative electrode active material, a functional group containing oxygen is contained in a petroleum pitch having a hydrogen / carbon element ratio of 0.6 to 0.8.
A carbonaceous material obtained by firing a material (precursor) introduced so as to have an oxygen content of 10 to 20% by weight can also be preferably used.

Further, when carbonizing the above-mentioned furan resin or petroleum pitch, a phosphorus compound or a boron compound is added to use a carbonaceous material having a large amount of lithium that can be doped and undoped. be able to.

As the positive electrode active material of the cylindrical nonaqueous electrolyte secondary battery of the present invention, Li _x MO ₂ (M represents one or more transition metals, preferably at least one of Co or Ni,
0.05 ≦ x ≦ 1.10.). Specifically, Li
_{x CoO 2, Li x NiO 2} , Li x Ni y Co 1-y O 2 ( however, 0.05 ≦ x ≦ 1.10,0 <y <1) is a composite oxide represented by like preferably.

These composite oxides can be obtained, for example, by mixing carbonates such as lithium, cobalt, nickel and the like according to the composition, and calcining the mixture in a temperature range of 600 to 1000 ° C. in an atmosphere containing oxygen. The starting materials are not limited to carbonates, and can be synthesized from hydroxides and oxides.

The separator 3 interposed between the strip-shaped negative electrode 1 and the strip-shaped positive electrode 2 is preferably a microporous polypropylene film.

As the electrolytic solution of the cylindrical nonaqueous electrolyte secondary battery of the present invention, a solution in which an electrolyte such as a lithium salt is dissolved in an organic solvent can be used. Here, the organic solvent is not particularly limited, but, for example, propylene carbonate, ethylene carbonate, diethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyllactone, tetrahydrofuran,
A single solvent or a mixed solvent of two or more such as 1,3-dioxolan, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile and the like can be used.

As the electrolyte, any of conventionally known electrolytes can be used, and LiClO ₄ , LiAsF ₆ , LiPF
₆ , LiBF ₄ , Li (C ₆ H ₅ ) ₄ , LiCl, LiB
r, CH ₃ SO ₃ Li, CF ₃ SO ₃ Li and the like.

Other components of the non-aqueous electrolyte secondary battery of the present invention, such as a cylindrical battery can, a negative electrode or a positive electrode current collector, a battery cover, and a gasket, are the same as those of a conventional non-aqueous electrolyte secondary battery. Configuration.

The non-aqueous electrolyte secondary battery of the present invention is, for example,
It can be manufactured as described below.

First, a strip-shaped negative electrode, a separator, a strip-shaped positive electrode,
And four layers in the order of the separator. At this time, the strip-shaped positive electrode is arranged such that the longer surface of the portion coated with the positive electrode mixture faces the strip-shaped negative electrode with the separator interposed therebetween. The laminated body is wound many times in a spiral shape along the length direction such that the end of the side where the positive electrode mixture is applied to both sides of the band-shaped positive electrode is started and the band-shaped positive electrode is outside the band-shaped negative electrode. Thus, a spiral electrode body is manufactured. Then, an adhesive tape is applied to the end of the spiral electrode body. At this time, a part of the adhesive tape is bent and bonded to the end of the spiral electrode body on the negative electrode lead extraction side.

Next, the spirally wound electrode body thus manufactured is housed in a cylindrical battery can. At this time, insulating plates are provided on both upper and lower surfaces of the spiral electrode body. Further, a negative electrode lead for electrically connecting the belt-shaped negative electrode and the cylindrical battery can is led out from the negative electrode current collector and welded to the cylindrical battery can.

Next, after injecting the electrolytic solution into the cylindrical battery can, a positive electrode lead for electrically connecting the belt-shaped positive electrode and the battery lid is led out from the positive electrode current collector and welded to the safety valve.
Then, the safety valve having the current cutoff mechanism and the battery lid are fixed by caulking the spirally wound electrode body and the cylindrical battery can containing the electrolyte through an insulating sealing gasket. Thus, a cylindrical non-aqueous electrolyte secondary battery can be manufactured.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to FIGS.

Example 1 (Preparation of strip-shaped negative electrode) Using a petroleum pitch as a starting material,
After oxygen cross-linking, 1000 g
C. to obtain a carbonaceous material having properties similar to glassy carbon. A carbon material powder having an average particle size of 20 μm obtained by pulverizing the carbonaceous material was used as a negative electrode active material. X-ray diffraction measurement of this material showed that the (002) plane spacing was 3.8 °. The true specific gravity measured by the Pycnometer method was 1.54 g / cm ³ .

90 parts by weight of the negative electrode active material thus obtained and 10 parts by weight of vinylidene fluoride resin as a binder were mixed to prepare a negative electrode mixture. This negative electrode mixture was dispersed using N-methylpyrrolidone as a solvent to form a slurry (paste). A strip-shaped copper foil having a thickness of 15 μm was used as the negative electrode current collector, a negative electrode mixture slurry was applied to both surfaces of the current collector, and the solvent was removed by drying. The thickness of the mixture after molding is 80 on both sides.
μm, the width of the electrode is 54.5 mm, and the length is 52
0 mm.

(Preparation of Stripped Positive Electrode) 0.5 mol of lithium carbonate and 1 mol of cobalt carbonate were mixed, baked in air at 900 ° C. for 5 hours, and then pulverized.
5 μm LiCoO ₂ powder was used as a positive electrode active material.
X-ray diffraction measurement was performed on the obtained material.
The peak coincided well with the LiCoO ₂ peak registered in the PDS film. A positive electrode mixture is prepared by mixing 91 parts by weight of a mixture of 95 parts by weight of the positive electrode active material and 5 parts by weight of lithium carbonate powder, 6 parts by weight of graphite as a conductive agent, and 3 parts by weight of vinylidene fluoride resin as a binder. And N-
Slurry (paste) dispersed in methylpyrrolidone
I made it.

Next, the obtained positive electrode mixture slurry was applied to one surface of a 20 μm-thick strip-shaped aluminum foil serving as a positive electrode current collector, having a length of 470 mm, dried, and then applied to the back surface thereof. And the coating start position were matched, and the positive electrode mixture slurry was applied in a length of 444 mm. This is dried, compression molded, and has a width of 53.5 mm, the length of the portion coated with the positive electrode mixture on both surfaces is 444 mm, the length of the portion coated with the positive electrode mixture on one surface is 26 mm, and the thickness of the mixture. Is 8 on both sides
A belt-shaped positive electrode 2 of 0 μm was produced.

As described above, when the positive electrode mixture is applied to the positive electrode current collector, the energy density of the nonaqueous electrolyte secondary battery can be improved by providing the uncoated portion. This is because, as shown in JP-A-5-234620, by providing a band-shaped positive electrode with an uncoated material, the amount of the negative electrode active material that does not contribute to the battery reaction inside the battery can be reduced, and the inside of the battery can can be reduced. This is because the volume can be effectively used.

(Preparation of Electrolyte Solution) In a mixed solvent of equal volumes of propylene carbonate and diethyl carbonate, Li
A solution in which PF ₆ was dissolved at a rate of 1 mol / dm ³ was prepared as an electrolyte.

(Manufacture of spiral electrode body) A microporous polypropylene film having a thickness of 25 μm and a width of 58 mm was used as the separator 3 interposed between the strip-shaped negative electrode 1 and the strip-shaped positive electrode 2 thus manufactured. Four layers of the band-shaped negative electrode 1, the separator 3, the band-shaped positive electrode 2, and the separator 3 were laminated in this order. At this time, the strip-shaped positive electrode 2 was disposed such that the longer surface of the mixture-applied portion faced the strip-shaped negative electrode 1 with the separator 3 interposed therebetween. Then, a number of the laminates are spirally wound along the length direction such that the end of the side where the mixture is applied to both sides of the band-shaped positive electrode 2 is started and the band-shaped positive electrode 2 is located outside the band-shaped negative electrode 1. Wound.

Next, an adhesive tape in which a silicone-based adhesive was applied to a 25 μm-thick polyester film support was cut into a width of 4.9 mm and a length of 45.5 mm. And the bent portion 20a of the adhesive tape was stuck to the negative electrode lead take-out side end 15a of the spiral electrode body so that the length L of the bent portion was 5.5 mm. Thereby, the spiral electrode body 15 (with an outer diameter of 1) having a structure as shown in FIG.
6.5 mm).

(Assembly of Battery) As shown in FIG. 1, the spirally wound electrode body 15 manufactured as described above was housed in a nickel-plated iron cylindrical battery can 5 having an inner diameter C of 17.2 mm. Insulating plates 4 are provided on the upper and lower surfaces of the spiral electrode body 15, and a nickel negative electrode lead 11 is drawn out of the negative electrode current collector 9 to electrically connect the strip-shaped negative electrode 1 and the cylindrical battery can 5. And welded to the cylindrical battery can 5.

After injecting the above-mentioned electrolytic solution into the cylindrical battery can 5, an aluminum positive electrode lead 12 for electrically connecting the belt-shaped positive electrode 2 and the battery cover 7 is connected to the positive electrode current collector 1.
0 and was welded to the safety valve 8. Then, the spiral-wound electrode body 15 and the cylindrical battery can 5 containing the electrolytic solution are caulked through an insulating sealing gasket 6 coated with asphalt on the surface to thereby provide a safety valve 8 having a current interruption mechanism and a battery lid 7. Was fixed. Thus, a cylindrical nonaqueous electrolyte secondary battery having a diameter of 17.9 mm and a height of 64 mm as shown in FIG. 1 was produced.

Example 2 The length of the strip-shaped negative electrode 1 was 540 mm,
The length of each of the strip-shaped negative electrodes 1 and 2 was increased by setting the length of the portion where the positive electrode mixture was applied to both surfaces of 461 mm to obtain a spiral electrode body having an outer diameter of 16.6 mm according to the operation of Example 1. Produced.

An adhesive tape 2 using the obtained spiral electrode body and fixing the outermost end of the spiral electrode body to the winding end.
A non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1, except that the width of the zero and the width D of the bent portion 20a were 4.5 mm.

Example 3 Example 2 was the same as Example 2 except that the length of the adhesive tape 20 for fixing the outermost end portion of the spirally wound electrode body was 51.1 mm, and the length L of the bent portion 20a was 11.1 mm. A non-aqueous electrolyte secondary battery was manufactured in the same manner.

Example 4 Example 2 was the same as Example 2 except that the length of the adhesive tape 20 for fixing the outermost end portion of the spirally wound electrode body was 56.6 mm and the length L of the bent portion 20a was 16.6 mm. A non-aqueous electrolyte secondary battery was manufactured in the same manner.

Example 5 The same procedure as in Example 2 was repeated except that the width of the adhesive tape 20 for fixing the outermost end portion of the spirally wound electrode body and the width D of the bent portion 20a were 6.4 mm. An electrolyte secondary battery was manufactured.

Example 6 The same procedure as in Example 2 was carried out except that the width of the adhesive tape 20 for fixing the outermost end of the spiral electrode body and the width D of the bent portion 20a were 7.8 mm. An electrolyte secondary battery was manufactured.

Example 7 The same procedure as in Example 2 was repeated except that the width of the adhesive tape 20 for fixing the outermost end of the spiral electrode body and the width D of the bent portion 20a were 9.0 mm. An electrolyte secondary battery was manufactured.

Embodiment 8 The width of the adhesive tape 20 for fixing the outermost end portion of the outermost periphery of the spiral electrode body is set to 9.0 mm, and the bent portion 20a is cut along a line bisecting the tape width as shown in FIG. The adhesive tape 20 is formed with two bent portions 20a each having a width of 4.5 mm.
A non-aqueous electrolyte secondary battery was fabricated in the same manner as in Example 2, except that the electrode a was bent toward the center of the end portion 15a on the negative electrode lead take-out side of the spiral electrode body and bonded.

Comparative Example 1 The length of the adhesive tape 20 for fixing the end of the outermost periphery of the spiral electrode body is 40 mm, and the length L of the bent portion 20a is 0.
mm, that is, the same method as that of Example 1 was adopted except that one end in the length direction of the tape was aligned with the end 15a on the negative electrode lead extraction side of the spiral electrode body without providing a bent portion as shown in FIG. .

Comparative Example 2 The length of the adhesive tape 20 for fixing the end of the outermost periphery of the spiral electrode body was 40 mm, and the length L of the bent portion 20a was 0.
mm, that is, the same method as that of Example 2 was adopted except that one end in the length direction of the tape was aligned with the end 15a on the negative electrode lead take-out side of the spiral electrode body without providing a bent portion as shown in FIG. .

(Evaluation) 1000 batteries were prepared for each of the examples and comparative examples, and the upper limit voltage of the batteries was set to 4. except for defective products in the step of inserting the spiral electrode body 15 into the cylindrical battery can 5. After charging for 7 hours at a constant current of 1 A at 2 V, 40
A charge / discharge cycle of discharging to 2.75 V at a constant current of 0 mA was repeated.

The outer diameter R of the spiral electrode body 15 and the spiral electrode body 15 of the nonaqueous electrolyte secondary battery in each of the examples and comparative examples.
Bent portion 2 of adhesive tape 20 for fixing the end of winding
Width D of 0a, length ^{L, D 2 / (C 2} -R 2) values, L / R
Value, average value of the discharge capacity at the 10th cycle, and the battery 10
Table 1 shows the number of defective products due to improper insertion of the spiral electrode body in 00 pieces.
Shown in

[0063]

[Table 1] R value Tape width D value L value D ² / (C ² -R ² ) L / R Average discharge Number of defective products (mm) (mm) (mm) (mm) Capacity (mAh) (this) Example 1 16.5 4.9 4.9 5.5 1.0 0.33 1520 0 Example 2 16.6 4.5 4.5 5.5 1.0 0.33 1578 2 Example 3 16.6 4.5 4.5 11.1 1.0 0.67 1578 2 Example 4 16.6 4.5 4.5 16.6 1.0 1.00 1578 2 Example 5 16.6 6.4 6.4 5.5 2.0 0.33 1578 1 Example Example 6 16.6 7.8 7.8 5.5 3.0 0.33 1578 3 Example 7 16.6 9.0 9.0 5.5 4.0 0.33 1578 15 Example 8 16.6 9.0 4.5 5.5 1.0 0.33 1578 0 Comparative example 1 16.5 4.9-0.0-0.00 1520 5 Comparative example 2 16.6 4.5-0.0 -0.00 1578 32

As shown in Table 1, the battery of Comparative Example 2 has a larger discharge capacity than the battery of Comparative Example 1, but also has a larger number of defective products. Observation of the spirally wound electrode body in which the insertion failure occurred in Comparative Examples 1 and 2 revealed that the pressure-sensitive adhesive tape was partially peeled off, and the outermost electrode and the separator were partially turned up from that part. This is because the outer diameter R of the spiral electrode body is increased, the clearance between the inner wall of the cylindrical battery can is reduced, and the inner wall of the battery can and the adhesive tape, or the inner wall of the battery can and the outermost periphery of the spiral electrode body are reduced. It is considered that the friction and collision of the tire became easy to occur.

On the other hand, in Example 1, there was no defective product, and in Examples 2 to 6, the number of defective products was 1 to 3 even though R was increased to 16.6 mm. Very few compared to 2. This is because contact between the tape end and the inner wall of the battery can is avoided by bending the adhesive tape to the end of the spiral electrode body where the negative electrode lead is taken out,
As a result, it is considered that the pressure-sensitive adhesive tape was less likely to peel off due to friction with the inner wall of the battery can, and the insertion step became smooth.

Since there is almost no difference in the number of defective products in Examples 2 to 6, 0 <L / R ≦ 1 and D ² / (C ² -R
² ) It can be said that the effect of the present invention does not change in the range of ≦ 3.

However, in Example 7 in which the adhesive tape was bent and bonded in the same manner, the number of defective products increased to 15. This is presumably because the width D of the bent portion of the pressure-sensitive adhesive tape was too large, the wrinkles of the pressure-sensitive adhesive tape caused by the bending became large, and the clearance between the spiral electrode body and the inner wall of the cylindrical battery can was reduced. In Example 8, an adhesive tape having the same width as that of Example 7 was used. However, since the bent portion was divided so that the width D satisfied D ² / (C ² −R ² ) ≦ 3, the adhesive tape was Example 1
It is considered that the number was about the same as 6, and the number of defective products was suppressed to zero.

Further, by using a wide adhesive tape, the adhesive area between the tape and the spiral electrode body is increased, and the fixing strength against loosening of the spiral electrode body can be increased. Therefore, in order to obtain a high yield rate and a high capacity, as in Example 8, the width of the adhesive tape is widened so as to obtain a sufficient fixing strength, and the bent portion has a width D of D ² / (C ² −
It can be seen that it is desirable to divide the image into a plurality of pieces so as to satisfy R ² ) ≦ 3.

[0069]

According to the cylindrical non-aqueous electrolyte secondary battery of the present invention, the energy density of the battery can be improved without lowering the yield rate when the spiral electrode body is inserted into the cylindrical battery can. be able to.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cylindrical non-aqueous electrolyte secondary battery of the present invention.

FIG. 2 is a schematic perspective view of a spiral electrode body used in the cylindrical nonaqueous electrolyte secondary battery of the present invention.

FIG. 3 is an explanatory diagram of a shape of an adhesive tape for fixing a spiral electrode body.

FIG. 4 is a schematic perspective view of a spiral electrode body used in a conventional cylindrical nonaqueous electrolyte secondary battery.

[Explanation of symbols]

1 ... Strip negative electrode, 2 ... Strip positive electrode, 3 ... Separator,
4 ... insulating plate, 5 ... cylindrical battery can 6 ... gasket, 7
... battery lid, 8 ... safety valve, 9 ... negative electrode current collector, 10 ... positive electrode current collector, 11 ... negative electrode lead, 12 ... positive electrode lead,
15: spiral electrode body 20: adhesive tape

Claims (2)

[Claims] 1. A spirally wound electrode body in which a strip-shaped negative electrode and a strip-shaped positive electrode are spirally wound with a separator interposed therebetween, and an end portion of which is fixed using an adhesive tape, together with a non-aqueous electrolyte in a cylindrical battery can. A cylindrical non-aqueous electrolyte secondary battery, wherein a part of the pressure-sensitive adhesive tape is bent and adhered to the end of the spiral electrode body on the side where the negative electrode lead is taken out. Rechargeable battery. 2. The width of the bent portion of the adhesive tape which is bent and adhered to the end of the spiral electrode body on the negative electrode lead extraction side is D, the length is L, and the outer diameter of the spiral electrode body is R, when the inner diameter of the battery can is C, the following equations (1) and (2): D ² / (C ² −R ² ) ≦ 3 (1) 0 <L / R ≦ 1 (2) The cylindrical non-aqueous electrolyte secondary battery according to claim 1, wherein