JP4889313B2 - Nonaqueous electrolyte secondary battery - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte secondary battery having a flat wound electrode body, and in particular, a flat wound electrode body excellent in cycle characteristics with little increase in internal resistance due to repeated charge / discharge cycles. The present invention relates to a nonaqueous electrolyte secondary battery.

  With the rapid spread of portable electronic devices, the required specifications for the batteries used for them are becoming stricter year by year, and in particular, there are demands for smaller, thinner and higher capacity. Therefore, there is a demand for stable performance with little deterioration due to the charge / discharge cycle. In the field of secondary batteries, lithium ion non-aqueous electrolyte secondary batteries, which have a higher energy density than other batteries, are attracting attention. The proportion of lithium ion non-aqueous electrolyte secondary batteries accounts for a significant increase in the secondary battery market. Is shown.

  By the way, in a device in which this type of nonaqueous electrolyte secondary battery is used, the space for housing the battery is often a square (flat box), and therefore the power generating element is a flat wound electrode body. In many cases, a rectangular nonaqueous electrolyte secondary battery formed by accommodating the flat wound electrode body in a rectangular outer can is used. An example of such a rectangular nonaqueous electrolyte secondary battery will be described with reference to the drawings.

  FIG. 5 is a perspective view showing a conventional non-aqueous electrolyte secondary battery cut in the longitudinal direction. The nonaqueous electrolyte secondary battery 10 accommodates a flat wound electrode body 14 in which a positive electrode plate 11 and a negative electrode plate 12 are wound via a separator 13 in a rectangular battery outer can 15. The battery outer can 15 is sealed with a sealing plate 16. The flat wound electrode body 14 is wound so that the positive electrode plate 11 is exposed at the outermost periphery, and the exposed outermost positive electrode plate 11 is the inner surface of the battery outer can 15 that also serves as a positive electrode terminal. Is in direct contact and is electrically connected. Further, the negative electrode plate 12 is electrically connected to a negative electrode terminal 18 attached to the center of the sealing plate 16 via an insulator 17 by a current collector 19.

  Since the battery outer can 15 is electrically connected to the positive electrode plate 11, in order to prevent a short circuit between the negative electrode plate 12 and the battery outer can 15, the upper end and the sealing end of the flat wound electrode body 14 are sealed. The insulating spacer 20 is inserted between the plate 16 and the negative electrode plate 12 and the battery outer can 15 are electrically insulated. In this rectangular nonaqueous electrolyte secondary battery 10, after the flat wound electrode body 14 is inserted into the battery outer can 15, the sealing plate 16 is laser welded to the opening of the battery outer can 15, and then the electrolytic solution The non-aqueous electrolyte is injected from the injection hole 21 and the electrolyte injection hole 21 is sealed. Such a rectangular non-aqueous electrolyte secondary battery 10 has an excellent effect that there is little wasted space during use, and the battery performance and battery reliability are high.

  In addition, such a flat wound electrode body 14 is normally manufactured by the following manufacturing method as disclosed in, for example, Patent Document 1 below. That is, a positive electrode plate 11 is manufactured by coating a positive electrode active material mixture containing a positive electrode active material on both surfaces of a positive electrode core made of a long and thin sheet-like aluminum foil. A negative electrode plate 12 is produced by coating a negative electrode active material mixture containing a negative electrode active material on both sides of the core, and a microporous polypropylene film or the like is used as the separator 13, and the positive electrode plate 11 and the negative electrode plate 12 are used. Are separated from each other by a separator 13 and wound into a columnar shape or an elliptical shape, and then further crushed to form a flat shape.

  By the way, as the copper foil as the negative electrode current collector, an electrolytic copper foil or a rolled copper foil is generally used. However, the electrolytic copper foil has a high adhesion strength with the negative electrode active material mixture due to rough surface irregularities, but has a problem that the thickness of the copper foil cannot be reduced too much because the strength of the copper foil is weak. On the other hand, since the rolled copper foil has a high strength, the thickness can be reduced. However, since the surface is smooth, there is a problem that the adhesion strength of the negative electrode active material mixture is weak. Therefore, as shown in the following Patent Document 2, there is also known one using a copper foil whose surface is roughened by attaching fine copper particles to the surface of the rolled copper foil by an electrolytic method.

Japanese Patent Laying-Open No. 2004-241182 (paragraphs [0004] to [0005]) Japanese Unexamined Patent Publication No. 2000-200670 (claims, paragraphs [0002] to [0004], [0048] to [0063], FIG. 1)

  However, when a charge-discharge cycle is repeated, a rectangular non-aqueous electrolyte secondary battery that has been used conventionally has a deflection in the wound electrode body due to repeated expansion and contraction of the electrode active material, particularly the negative electrode active material. The battery has been deteriorated by increasing the internal resistance of the rotating electrode body. Conventionally, in order to improve the charge / discharge cycle characteristics of the non-aqueous electrolyte secondary battery, various improvements have been made mainly from a chemical viewpoint, such as a positive electrode active material mixture composition, a negative electrode active material mixture composition, and an electrolyte solution composition. However, a method that effectively suppresses the deflection of the wound electrode body due to the charge / discharge cycle, suppresses an increase in the internal resistance of the battery, and improves the cycle characteristics is known to be satisfactory to date. It was not done.

  Accordingly, the inventors of the present application have repeated various experiments paying attention to the physical properties of the copper foil, which is the negative electrode core, which has a large expansion and contraction of the active material during the charge / discharge cycle. Using a device with a specified amount of warping (sometimes called "convex") and making the winding direction a specific direction dramatically reduces the occurrence of deflection of the flat wound electrode body. It was found that the cycle characteristics of the nonaqueous electrolyte secondary battery were improved, and the present invention was completed.

  That is, the present invention provides a non-aqueous electrolyte secondary battery including a flat wound electrode body that is less likely to bend even when the charge / discharge cycle is repeated and has improved charge / discharge cycle characteristics. For the purpose.

  The above object of the present invention can be achieved by the following configurations. That is, the invention of the nonaqueous electrolyte secondary battery according to claim 1 is a flat shape in which a negative electrode plate having a negative electrode active material mixture provided on a negative electrode core made of copper foil and a positive electrode plate are wound through a separator. In a non-aqueous electrolyte secondary battery having a spirally wound electrode body, a copper foil is cut into a width of 30 cm and a length of 60 cm as a negative electrode core, and warping occurs when left on a horizontal table. A copper foil having an average value (warpage amount) of 5 mm or more on two sides is used, and the winding direction at the time of manufacturing a wound electrode body is wound along the warping direction of the copper foil. .

  In general, there is no method for measuring the amount of warpage that has been standardized over various technical fields. Therefore, in the present invention, the amount of warpage of the copper foil is determined as follows. It is defined and used as “the average value of the amount of warping of two opposing sides where warping has occurred”.

  Examples of the negative electrode active material that can be used in the nonaqueous electrolyte secondary battery of the present invention include natural graphite, artificial graphite, fibrous graphite, coke, mesocarbon microbeads, mesophase pitch-based carbon fiber, polyacrylonitrile-based carbon fiber, and the like. Well-known carbonaceous materials can be used. In particular, a negative electrode active material made of a graphite material has a discharge potential comparable to that of lithium metal or lithium alloy, but has high safety because dendrite does not grow, and further has excellent initial efficiency and potential flatness. It is preferable because it has excellent properties such as good and high density.

Similarly, as the positive active material, lithium transition metal composite oxide represented by LixMO ₂ (wherein M is at least one of Co, Ni, and Mn) capable of reversibly occluding and releasing lithium, That is, LiCoO ₂ , LiNiO ₂ , LiNiyCo _1-y O ₂ (y = 0.01 to 0.99), LiMnO ₂ , LiMn ₂ O ₄ , LiCo _x Mn _y Ni _z O ₂ (x + y + z = 1) and the like. These can be used alone or in combination.

  Furthermore, as the non-aqueous solvent (organic solvent) constituting the non-aqueous electrolyte that can be used in the method for producing the non-aqueous electrolyte secondary battery of the present invention, ethylene carbonate (EC), propylene carbonate, butylene carbonate, cyclopentanone, Sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, 3-methyl-1,3-oxazolidine-2-one, dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), methyl propyl carbonate, Methyl butyl carbonate, ethyl propyl carbonate, ethyl butyl carbonate, dipropyl carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetra Hydrofuran, 1,3-dioxolane, methyl acetate, ethyl acetate, 1,4-dioxane and the like can be mentioned. In the present invention, a mixed solvent such as chain carbonates such as EC and DMC, MEC, and DEC is preferably used from the viewpoint of increasing the charge / discharge efficiency. However, since cyclic carbonates are generally oxidatively decomposed at a high potential, The EC content in the electrolyte is preferably 5% by volume or more and 25% by volume or less.

In addition, as a solute of a nonaqueous electrolyte that can be used in the method for producing a nonaqueous electrolyte secondary battery of the present invention, a lithium salt generally used as a solute in a nonaqueous electrolyte secondary battery can be used. Such lithium salts include LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiAsF ₆ , LiClO ₄ , Li ₂ B ₁₀ Cl ₁₀ , Li ₂ B ₁₂ Cl ₁₂ , and mixtures thereof Illustrated. Among these, LiPF ₆ (lithium hexafluorophosphate) is preferably used. The amount of solute dissolved in the non-aqueous solvent is preferably 0.5 to 2.0 mol / L.

  The invention according to claim 2 is characterized in that, in the nonaqueous electrolyte secondary battery according to claim 1, an electrolytic copper foil is used as the copper foil.

  Moreover, the invention which concerns on Claim 3 was manufactured using the cathode for electrolytic copper foil manufacture in which the surface was grind | polished and roughened as said electrolytic copper foil in the nonaqueous electrolyte secondary battery of Claim 2. It is characterized by using things.

  According to a fourth aspect of the present invention, in the nonaqueous electrolyte secondary battery according to the third aspect, the cathode for producing the electrolytic copper foil is roughened by using an abrasive having a particle size of # 2000 or less and # 500 or more. It is characterized by being made.

  The invention according to claim 5 is the nonaqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the copper foil wound in a roll shape is 40 ° C. or more and 60 ° C. or less as the copper foil. Thus, a material aged from 24 hours to 100 hours is used.

  By providing the above configuration, the present invention has the following excellent effects. That is, according to the invention of claim 1, since the stress generated by repeating the charge / discharge cycle is suppressed by the warp of the copper foil, the amount of deflection of the negative electrode plate is reduced even when the charge / discharge cycle is repeated, A nonaqueous electrolyte secondary battery having good cycle characteristics can be obtained. Further, since it is only necessary to give a certain amount of warpage to the copper foil, a nonaqueous electrolyte secondary battery with improved charge / discharge cycle characteristics can be easily obtained. If the amount of warpage is less than 5 mm, the degree of flexure of the flat wound electrode body when the charge / discharge cycle is repeated cannot be suppressed, and the cycle characteristics deteriorate. The upper limit of the warpage amount is naturally determined by the copper foil manufacturing method, and it is better that the warpage amount is larger, but there is no critical limit.

  According to the second aspect of the invention, the electrolytic copper foil is generally rotated at a constant speed by supplying a sulfuric acid-copper sulfate aqueous solution between a cylindrical cathode drum that rotates at a constant speed and an anode facing it. Since it is manufactured by depositing copper on the cathode surface and then peeling off, the resulting copper foil warps in the opposite direction to the cathode drum. Therefore, a copper foil having a predetermined warpage amount can be easily obtained.

  According to the invention of claim 3, when the copper foil produced using the electrolytic copper foil production cathode whose surface has been polished and roughened has high adhesion strength with the cathode, Thus, a large force is required, and as a result, a copper foil having a large amount of warpage can be obtained.

  According to the invention of claim 4, the cathode for producing electrolytic copper foil is roughened by polishing with an abrasive having a particle size of # 2000 or less and # 500 or more, that is, an abrasive having a particle size that is somewhat large. Therefore, an electrolytic copper foil having a warp amount of 5 mm or more can be easily obtained. If the abrasive particle size exceeds # 2000, the surface of the cathode for producing electrolytic copper foil is too smooth and the amount of warpage cannot be easily increased to 5 mm or more, and the abrasive particle size is less than # 500. If it is, the surface of the cathode for producing an electrolytic copper foil becomes too rough, the force necessary to peel off the obtained electrolytic copper foil becomes too large, and the copper foil is easily cut off.

  Moreover, according to the invention which concerns on Claim 5, even if it is copper foil with small curvature amount, the copper foil wound by roll shape is 40 to 60 degreeC, 24 to 100 hours aged. Thus, it is possible to easily obtain a copper foil having a warp amount of 5 mm or more. If the temperature during aging is less than 40 ° C, it takes more than 100 hours to make the warpage amount 5 mm or more, and if the temperature during aging exceeds 60 ° C, it becomes an annealed state and the amount of warpage. Is not preferable because it decreases.

  Hereinafter, the best mode for carrying out the present invention will be described in detail using examples and comparative examples. The configuration of the nonaqueous electrolyte secondary battery used in this example and the comparative example is substantially the same as that of the conventional nonaqueous electrolyte secondary battery shown in FIG. 1, so refer to the drawings as necessary. I will explain it. However, the examples shown below illustrate an example of a rectangular non-aqueous electrolyte secondary battery as a non-aqueous electrolyte secondary battery for embodying the technical idea of the present invention. The present invention is not intended to be specified by way of example, and the present invention can be equally applied to various modifications without departing from the technical concept shown in the claims.

  First, a specific method for manufacturing a nonaqueous electrolyte secondary battery common to Examples and Comparative Examples and a method for measuring various characteristics will be described with reference to FIG. In addition, FIG. 1 is a perspective view for demonstrating the measuring method of the curvature amount of copper foil.

[Copper foil manufacturing method]
A cylindrical cathode drum that has a cylindrical cathode drum surface roughened with an abrasive having a particle size of # 1000 in a commonly used electrolytic copper foil manufacturing apparatus and rotates at a constant speed according to a steady method, and A sulfuric acid-copper sulfate aqueous solution was supplied between the anodes facing each other, copper was extracted onto a cathode drum which was a hidden surface rotating while energized, and the electrolytic copper foil was peeled off and wound into a roll. Three types of electrolytic copper foils (A1, A2, B1) having different warpage amounts were obtained by changing the tension applied to the copper foil at the time of peeling of the electrolytic copper foil in three ways. Subsequently, the three types of copper foils wound up in this roll shape were both aged at 40 ° C. for 48 hours. The thickness of the obtained copper foil was 10 μm for all three types.

[Measurement method of warpage]
As shown in FIG. 1, each of the three types of copper foil wound up in a roll shape is cut out so that the width W is 30 cm and the length L is 60 cm. It was. These three types of copper foil samples for measuring the amount of warpage warped in one direction immediately after cutting. Next, the three types of cut copper foil samples for measuring the amount of warpage were placed on a flat table so that the direction in which the copper foil warps was up. The surface in the warped direction corresponds to the surface that is not in contact with the cathode roll during the production of the electrolytic copper foil. Then, for each sample, the heights H1 to H4 of the four sides are measured separately from the surface of the table at room temperature, and the average value ((H1 + H3) / 2 or (H2 + H4) of the heights of the two opposing sides where warpage occurs. ) / 2) was determined as the amount of warpage H of the copper foil sample. The warpage amounts H of these three types of samples were H = 3 mm (sample B1), H = 5 mm (sample A1), and H = 11 mm (sample A2), respectively.

[Production of negative electrode]
Dispersed graphite powder in water, added carboxymethylcellulose (CMC) as a thickener, dispersed styrene butadiene rubber (SBR) dispersion (solid content 48%) as water in water This was added to make a slurry. In this case, the negative electrode was prepared so that the mass composition ratio after drying was graphite: SBR: CMC = 100: 3: 2. This slurry was applied to both sides of the above three types of copper foils by the doctor blade method and vacuum-dried at 110 ° C. for 2 hours to form a negative electrode active material mixture layer having a thickness of 100 μm on both sides of the copper foils. Three types of formed negative electrode plates 12 were produced.

[Electrolyte and separator]
As the nonaqueous electrolytic solution, a solution obtained by dissolving LiPF _{6 in} a mixed solvent of EC and DEC in a volume ratio of 50:50 so as to be 1 mol / L was used. As the separator 13, a microporous film made of polypropylene was used.

[Production of positive electrode]
As a positive electrode active material mixture, 85 parts by mass of lithium cobaltate (LiCoO ₂ ), 5 parts by mass of graphite powder as a conductive agent, and 5 parts by mass of carbon black were sufficiently mixed. Thereafter, a vinylidene fluoride polymer as a binder dissolved in N-methyl-2-pyrrolidone (NMP) is mixed to a solid content of 5 parts by mass to prepare a positive electrode active material mixture slurry. did. The obtained positive electrode active material mixture slurry was applied to both surfaces of a positive electrode current collector (aluminum foil or aluminum alloy foil) having a thickness of 15 μm by the doctor blade method, and a positive electrode active material mixture layer was applied to both surfaces of the positive electrode current collector. Formed. Subsequently, after drying, the positive electrode plate 11 was produced by rolling with a roller press until a predetermined thickness was obtained.

[Production of battery]
Then, using the positive electrode plate 11 and the negative electrode plate 12 prepared as described above, the separator 13 is disposed between the positive electrode plate 11 and the negative electrode plate 12, and the positive electrode plate 11 and the negative electrode plate 12 are insulated from each other by the separator 13. A cylindrical wound electrode body was produced by spirally winding around a cylindrical winding core. Next, the winding core is taken out from this cylindrical wound electrode body, and the cylindrical wound electrode body is crushed with a press machine and molded into a flat shape so that it can be inserted into the rectangular battery outer can 15. Three types of prismatic nonaqueous electrolyte secondary batteries corresponding to the type of the plate 12 were produced. That is, the battery using the copper foil sample B1 as the core of the negative electrode plate is referred to as the battery b1 of Comparative Example 1, the battery using the copper foil sample A1 is referred to as the battery a1 of Example 1, and the battery using the copper foil sample A2 Was designated as battery a2 of Example 2. The design capacity of these three types of batteries is all 1000 mAh.

  Next, a charge / discharge cycle test was performed on the above three types of batteries b1, a1, and a2 under the following charge / discharge conditions. All charge / discharge cycle tests were conducted in a thermostatic chamber maintained at 25 ° C. First, each battery is charged at a constant current of 1 It (1 C) = 1000 mA, and after the battery voltage reaches 4.2 V, the current value becomes 1/50 It = 20 mA at a constant voltage of 4.2 V. The battery was charged and then discharged at a constant current of 1 It until the battery voltage reached 2.75 V, and the discharge capacity at this time was determined as the initial capacity.

Charging / discharging cycle characteristics were measured for each battery whose initial capacity was measured until the battery voltage reached 4.2 V at a constant current of 1 It until the current value became 1/50 It at a constant voltage of 4.2 V. The battery was charged and then discharged at a constant current of 1 It until the battery voltage reached 2.75 V as one cycle, and repeated until 500 cycles were reached to determine the discharge capacity in each cycle. And about each battery, the capacity | capacitance residual rate (%) after each cycle in 25 degreeC was calculated | required based on the following formulas. The results are shown in the graph of FIG. Further, the remaining capacity rate after 500 cycles for the above three types of batteries b1, a1, and a2 was determined and shown together with the amount of warpage in Table 1.
Capacity remaining rate (%) = (discharge capacity after each cycle / initial capacity) × 100

  From the measurement results of the number of cycles and the capacity remaining rate shown in FIG. 2 for the three types of batteries b1, a1, and a2, the following can be understood. That is, until about 200 cycles, there is substantially no difference in the change tendency of the capacity remaining rate between the three types of batteries b1, a1, and a2, but when the cycle exceeds 300 cycles, the capacity remaining rate of the battery b1 of the comparative example is implemented. It decreases more rapidly than the remaining capacity of the batteries a1 and a2 of Examples 1 and 2. On the other hand, the change tendency of the capacity remaining rate between the battery a1 of the example 1 and the battery a2 of the example 2 is substantially the same, but the battery a2 of the example 2 is slightly implemented when the cycle is nearly 500 cycles. The capacity remaining rate is larger than that of the battery a1 of Example 1. As shown in Table 1, the measurement result of the capacity remaining rate after 500 cycles was 58.5% for the battery b1 of Comparative Example 1, whereas it was 74.0% for the battery a1 of Example 1. In the battery a2 of Example 2, a result of 74.2% was obtained.

When the batteries a1 and a2 of Examples 1 and 2 after the elapse of 500 cycles and the battery b1 of the comparative example were cut in the lateral direction, the states of the outermost positive electrode plate 11 and negative electrode plate 12 were examined. In the case of batteries a1 and a2 of 2 and 2, as shown in FIG. 3, the battery b1 of the comparative example was as shown in FIG. That is, in the batteries a1 and a2 of Examples 1 and 2, the positive electrode plate 11 and the negative electrode plate 12 were not substantially deformed, whereas in the battery b1 of the comparative example, the negative electrode plate 12 had a lateral end. Deflection occurred at the point X near the part. Configuration of the battery b1 of Comparative Example 1 and battery a1 and a2 of Example 1 and 2 are not differences in the negative electrode active material mixture layer 12 ₂ structure provided on both surfaces of the negative electrode substrate 12 _1, a negative electrode because there is warpage only the difference of the copper foil used as the core body 12 ₁ of the plate 12, the difference in the effect of the battery b1 of Comparative example 1 and battery a1 and a2 of examples 1 and 2 of the negative electrode plate 12 it is clear that is caused by warpage of the difference of the copper foil used as the core body 12 _1. Therefore, in the present invention, if the amount of warpage H measured by the measuring method as shown in FIG. 1 is 5 mm or more and the winding direction at the time of manufacturing the wound electrode body is specified, it is shown in FIG. It can be seen that such a deflection does not occur and good charge / discharge cycle characteristics can be obtained.

  As described above, according to the embodiment of the present invention, a copper foil having a certain amount of warpage is used, and the copper foil is wound in the warping direction during the production of a flat wound electrode body. By repeating the charge / discharge cycle, even if the negative electrode active material repeatedly expands and contracts, it can suppress deflection due to the stress remaining in the copper foil, and has a long-life nonaqueous electrolyte with excellent charge / discharge cycle characteristics. A secondary battery can be obtained.

It is a perspective view which shows the curvature amount measuring method of the copper foil of a negative electrode core. 4 is a graph showing the relationship between the number of cycles and the capacity remaining rate of the nonaqueous electrolyte secondary batteries manufactured in Examples 1 and 2 and Comparative Example 1. It is a cross-sectional view after 500 cycles of the nonaqueous electrolyte secondary battery of Examples 1 and 2. It is a cross-sectional view after 500 cycles of the nonaqueous electrolyte secondary battery of a comparative example. It is a perspective view which cuts the square nonaqueous electrolyte secondary battery produced conventionally from the lengthwise direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Nonaqueous electrolyte secondary battery 11 Positive electrode plate 12 Negative electrode plate 12 ₁ Negative electrode core (copper foil)
12 ₂ Negative electrode active material mixture layer 13 Separator 14 Flat wound electrode body 15 Rectangular battery outer can 16 Sealing plate 17 Insulator 18 Negative electrode terminal 19 Current collector 20 Insulating spacer 21 Electrolyte injection hole

Claims (5)

In a nonaqueous electrolyte secondary battery having a flat wound electrode body in which a negative electrode plate having a negative electrode active material mixture layer provided on a negative electrode core body made of copper foil and a positive electrode plate are wound through a separator,
As the negative electrode core, the copper foil was cut into a width of 30 cm and a length of 60 cm, and the average value of the warping amounts of the two opposing sides where the warpage occurred when left on a horizontal table (hereinafter referred to as “warping amount”). The non-aqueous electrolyte secondary battery is characterized in that a copper foil of 5 mm or more is used and the winding direction at the time of manufacturing the wound electrode body is wound along the warping direction of the copper foil.   The nonaqueous electrolyte secondary battery according to claim 1, wherein an electrolytic copper foil is used as the copper foil.   The non-aqueous electrolyte secondary battery according to claim 2, wherein the electrolytic copper foil is manufactured using a cathode for manufacturing an electrolytic copper foil whose surface is roughened by polishing.   4. The nonaqueous electrolyte secondary battery according to claim 3, wherein the cathode for producing an electrolytic copper foil is roughened with an abrasive having a particle size of # 2000 or less and # 500 or more. The copper foil wound up in a roll shape is used at 40 ° C or more and 60 ° C or less for 24 hours or more and 100 hours or less, and the copper foil is used according to any one of claims 1 to 4. The nonaqueous electrolyte secondary battery as described.

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