JP4636920B2 - Battery with spiral electrode - Google Patents

Description

  The present invention relates to a battery of a spiral electrode in which a positive electrode and a negative electrode are wound in a spiral shape with a separator interposed between them and pressed from both sides to be housed in an exterior body with a predetermined thickness.

A battery has been developed in which a laminated body of a positive electrode, a negative electrode, and a separator is wound in a spiral shape and an electrode body having a predetermined thickness is pressed into an outer can (see Patent Document 1).
In this battery, after the electrode body wound in a spiral shape is pressed and processed to a predetermined thickness, when the pressed state is released, the electrode body expands and becomes thick due to the restoring property of the electrode. Furthermore, this electrode body becomes thicker by charging and discharging. That is, the electrode body having this structure has a drawback that it cannot be kept in the pressed thickness and becomes gradually thicker. Increasing battery thickness is never desirable in real-life conditions. This is because the battery has an adverse effect such as expanding the case of the electric device.

In order to prevent the above adverse effects, the battery is required to minimize the shape change in the usage state. In order to maintain the shape of the spiral electrode body, a technique has been developed in which electrodes are bonded and laminated with an adhesive (see Patent Documents 2 and 3).
The electrode bodies described in Patent Documents 2 and 3 have the drawback that the manufacturing process becomes complicated and the manufacturing cost increases because the electrodes are bonded with an adhesive. In addition, since an adhesive layer is provided between the electrodes, there is a disadvantage that the outer shape of the electrode body becomes large.
Furthermore, in order to ensure the adhesion between the core and the active material layer, a technique for identifying Ra (surface arithmetic average roughness) and Rz (surface ten-point average roughness) of the core surface has also been developed. (See Patent Document 4).
JP-A-8-339817 JP 2000-77091 A JP 2001-126769 A JP 2001-356855 A

  Specifying Ra (the arithmetic average roughness of the surface) and Rz (10-point average roughness of the surface) on the surface of the core is effective in improving the adhesive strength between the active material layer and the core. However, the spiral electrode body pressed to a predetermined thickness may be expanded after the electrode body is pressed depending on the technique for improving the adhesive strength between the core body and the active material layer by specifying Ra and Rz on the surface of the core body. In addition, it was not possible to prevent the drawbacks of thickening after charging and discharging.

  As a result of repeating various trials and errors for the purpose of solving the above disadvantages of the conventional spiral electrode body, the present inventor has an extremely simple structure, significantly reduces the swelling after pressing, and further charge / discharge. After that, we succeeded in reliably preventing the harmful effects of swelling. Therefore, an important object of the present invention is to provide a battery of a spiral electrode that has a simple structure and can significantly reduce deformation after pressing.

  The battery of the present invention has the following configuration in order to achieve the above-described object. In the battery of the spiral electrode, the electrode body 10 wound in a spiral shape is pressed in a heated state and processed into a predetermined thickness. The electrode body 10 is laminated so that the positive electrode plate / separator / negative electrode plate are uniformly opposed to each other, and is pressed so that the flat portion 11 is formed. As a result of repeating various experiments, the present inventor has found that the battery of this structure has a core body with respect to the adhesion between the active material portion of the electrode plate and the separator in continuous charge / discharge reactions (cycle, continuous charge). It was found that the separator has poor adhesion. Conventionally, it has been considered that the electrode body can be prevented from swelling due to a charge / discharge cycle by reliably adhering the active material layer of the electrode plate and the separator. However, surprisingly, it was found that the adhesion between the core body and the separator can be improved to prevent the electrode body from swelling due to the charge / discharge cycle, and the present invention has been realized.

  In particular, in a battery of a spiral electrode, when a core body in which an active material layer is not stacked is present at the beginning of the electrode plate at the center of the electrode body, swelling of the electrode body due to charge / discharge increases. This is because, when the electrode body having this structure is heated and pressed, both heat and pressure are hardly transmitted to the central portion of the electrode body, and it is difficult to stably adhere the electrode plate and the separator. For this reason, if the battery is repeatedly charged and discharged to increase the charge / discharge cycle or continuously charged, the core body and the separator are not in close contact with each other, loosening occurs, and the electrode body is deflected. The deflection of the electrode body swells the central part of the battery and creates a distance between the positive electrode and the negative electrode, thereby inhibiting normal charge / discharge reaction. As a countermeasure for solving this drawback, a method of increasing the press pressure of the spiral electrode body to improve the adhesion between the core body and the separator can be considered. However, according to this method, the separator is over-compressed and the porosity is lowered, thereby lowering the performance of the battery such as load characteristics, low-temperature characteristics, and safety.

  In the present invention, in order to eliminate this drawback, the separator lamination surface 17 of the core body 4 directly laminated on the separator 3 is roughened, and the surface roughness pitch (Sm) is roughened to 50 μm or less. ing. However, in this specification, the “surface roughness pitch (Sm)” is a value measured according to “JIS B 0601-1994” using a stylus roughness meter with a stylus tip radius of 2 μm. To do. The surface roughness pitch (Sm) of the separator laminate surface 17 subjected to the roughening treatment is specified to be 50 μm or less. When the surface roughness pitch is larger than 50 μm, the adhesion between the core body and the separator is lowered, and the charge / discharge reaction is performed. This is because the shape of the electrode body cannot be stabilized and swells.

  The separator laminated surface 17 that has been roughened in this manner has a large bite area with the separator 3 in the pressing process of the electrode body 10 and is difficult to shift. For this reason, the adhesion degree of the separator lamination surface 17 of the core body 4 and the separator 3 is improved. Therefore, the electrode body 10 can be maintained in a stable shape without increasing the press pressure of the electrode body 10. This is effective not only in the electrode body 10 in which the separator laminated surface 17 is provided on both surfaces of the core body 4, but also in the electrode body in which the separator laminated surface is provided on one surface of the core body. This is because the adhesion between the separator laminate surface of the core and the separator is improved.

  In the battery according to claim 2 of the present invention, the separator laminated surface 17 is provided on the core body 4 of the electrode plate 1 laminated at the winding center portion of the electrode body 10, and the separator 3 is directly attached to the separator laminated surface 17. Laminated.

  In the battery according to claim 3 of the present invention, the separator 4 is directly laminated on the separator lamination surfaces 17 on both surfaces of the electrode plate 1 with both surfaces of the core body 4 as separator lamination surfaces 17.

  The battery according to claim 4 of the present invention is a lithium ion secondary battery, in which the core body 4 having the separator laminated surface 17 is made of metal foil, and the separator 3 is made of a microporous film made of plastic. Furthermore, in the battery according to claim 5 of the present invention, the electrode plate 1 having the separator lamination surface 17 is used as the negative electrode of the lithium ion secondary battery, and the metal foil is used as the copper foil.

  Further, in the battery according to claim 6 of the present invention, the lead 15 is connected to the separator lamination surface 17 of the core body 4.

  The spiral electrode battery according to the present invention has a simple structure and can significantly reduce deformation after pressing. The battery of the spiral electrode of the present invention is formed by pressing an electrode body obtained by laminating and winding a separator between a positive electrode plate and a negative electrode plate so that a flat portion is formed on the electrode plate. The separator plate is provided on the flat portion of the electrode plate so that the surface of the core is in direct contact with the separator. The surface roughness pitch (Sm) of the separator plate is roughened to 50 μm or less. This is because it is processed. Since the battery having this structure is laminated by pressing the separator directly on the surface of the separator lamination surface of the electrode plate roughened to a surface roughness pitch (Sm) of 50 μm or less, the degree of adhesion between the electrode plate and the separator As a result, the deformation of the electrode body after pressing can be remarkably reduced, and the amount of swelling of the battery thickness that occurs during cycle charge / discharge and continuous charge of the battery can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below exemplify spiral electrode batteries for embodying the technical idea of the present invention, and the present invention does not specify the following batteries.

  Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving problems” sections. It is added to the members. However, the members shown in the claims are not limited to the members in the embodiments.

  The spiral electrode battery shown in FIG. 1 is a prismatic battery, in which an electrode body 10 and an electrolytic solution are placed in an exterior body 20 which is a rectangular exterior can and the opening is sealed with a sealing plate 21. The electrode body 10 is obtained by laminating and winding a positive electrode plate 1A and a negative electrode plate 1B with a separator 3 interposed therebetween. In the following examples, a spiral electrode battery is described in detail as a lithium ion secondary battery. However, the present invention does not specify a battery as a lithium ion secondary battery, and may be a secondary battery such as a nonaqueous electrolyte secondary battery or an alkaline battery.

  As shown in the sectional view of FIG. 2, the battery electrode plate 1 has an active material layer 5 laminated on the surface of a core body 4. The core body 4 is a metal foil. The electrode body 10 having the core body 4 as a metal foil can reduce the electric resistance of the electrode plate 1. The metal foil of the core body 4 is an aluminum foil or a copper foil. In the lithium ion secondary battery, the core body 4 of the positive electrode plate 1A is made of aluminum foil, and the core body 4 of the negative electrode plate 1B is made of copper foil.

  The electrode plate 1 is provided with an active material layer 5 by applying an active material paste to the surface of the core body 4 and drying it. The active material layer 5 is not provided on the entire surface of both surfaces of the core body 4 but provided on the opposing surfaces of the positive electrode and the negative electrode.

  The electrode body 10 shown in the figure has the innermost peripheral electrode plate 16 as a negative electrode and the outermost peripheral electrode plate 6 as a positive electrode. The innermost peripheral electrode plate 16 which is a negative electrode is a copper foil, and the lead 15 is connected to the winding start portion. The winding start portion connecting the leads 15 is the flat portion 11 of the core body 4. The core body 4 of the electrode body 10 shown in the figure does not have the active material layer 5 on both surfaces of the winding start portion, but has a separator laminated surface 17 in which both surfaces are in direct contact with the separator 3. In this electrode body 10, both surfaces of the winding start portion of the core body 4 are the separator lamination surface 17, but one surface of the winding start portion can be the separator lamination surface.

  The copper foil which is the core body 4 is making the separator 3 contact the separator lamination surface 17 directly without passing through the active material layer 5. It is important for the separator laminated surface 17 of the core body 4 to improve the degree of adhesion with the separator 3 in a pressing process described later. After pressing, the degree of adhesion between the winding start portion of the core body 4 and the separator 3 can be improved, so that deformation of the electrode body 10 that occurs during cycle charge / discharge or continuous charge of the battery can be suppressed, and further, the amount of swelling of the battery thickness can be reduced. It is. In particular, since the winding start portion of the core body 4 is in the center of the electrode body 10, heat and pressure when the electrode body 10 is hot-pressed are smaller than those of the outer portion, and the separator body 3 is stably adhered to the separator body 3. It is difficult. If the battery is charged and discharged in a state where the adhesion between the core body 4 and the separator 3 is not sufficient, the winding start portion of the core body 4 and the separator 3 are not adhered, loosening occurs, and the shape of the electrode body 10 is stable. It becomes a shape that does not. The deflection of the electrode body 10 increases the thickness of the battery and becomes a factor that inhibits a normal charge / discharge reaction.

  The separator lamination surface 17 at the winding start portion of the core body 4 is roughened so that the surface roughness pitch (Sm) is 50 μm or less in order to improve the adhesion with the separator 3 and eliminate the above-described adverse effects. is doing. The reason why the surface roughness pitch (Sm) of the separator lamination surface 17 is specified to be 50 μm or less is that if it is larger than this, the amount of expansion of the pressed electrode body 10 becomes large.

  For example, a core electrode body having a separator lamination surface having a surface roughness pitch (Sm) of 60 μm has a thickness of 50 μm to 100 μm after one hour of pressing, and further has a surface roughness pitch (Sm ) Is 70 μm, the core electrode body has an expansion amount of 80 μm to 150 μm after 1 hour of pressing, and the core body of which the surface roughness pitch (Sm) is 80 μm is 1 hour after pressing. The amount of swelling is as extremely large as 100 μm to 200 μm. On the other hand, the electrode body 10 of the core body 4 in which the surface roughness pitch (Sm) of the separator lamination surface 17 is roughened to 50 μm can have an extremely small expansion amount after 20 hours of pressing, 20 μm to 50 μm. The electrode body 10 of the core body 4 having a surface roughness pitch (Sm) of 40 μm can be extremely reduced until the amount of expansion after 1 hour of pressing is almost negligible at 20 μm or less.

Furthermore, the electrode body 10 of the core body 4 having the surface roughness pitch (Sm) of the separator laminated surface 17 roughened to 50 μm or less can remarkably reduce the rate of increase in thickness after repeated charge / discharge cycles. The amount of change in thickness after the charge / discharge cycle varies with the surface roughness pitch (Sm). For example, when the thickness in the charge / discharge cycle of the electrode body of the core body having a surface roughness pitch (Sm) of the separator stack surface of 60 μm is measured as a reference, it is as follows.
The following shows the change in thickness with respect to the surface roughness pitch (Sm) of the separator laminate surface after 1 hour of pressing.
80 .mu.m ..... thicker from 150 to 200 .mu.m.
70 μm …… The amount of thickening is 50 μm or less.
60 μm ………… This is the reference value.
50 μm …… .. 50 μm to 150 μm thinner.
40 μm ............ 200 μm to 350 μm thinner.

  From the above, the electrode body 10 in which the surface roughness pitch (Sm) of the separator lamination surface 17 of the core body 4 is 50 μm or less is 50 μm compared to the electrode body in which the surface roughness pitch (Sm) is 60 μm. It is as thin as ˜350 μm. In other words, the rate of thickening after the charge / discharge cycle can be significantly reduced.

  Although this invention specifies the surface roughness pitch (Sm) of the separator lamination surface 17 to 50 micrometers or less, it does not specify the method of roughening. This is because the separator laminated surface 17 can be made to have a surface roughness pitch (Sm) of 50 μm or less by a roughening process that has already been developed, and by any roughening process that will be developed in the future.

  For example, when using an electrolytic metal foil manufactured by a method of growing a metal foil by plating on the surface of the drum, the surface roughness of the drum on which the electrolytic metal foil is deposited is adjusted, and a specific surface is formed on the drum surface. A metal foil roughened to a roughness pitch (Sm) can be produced. This roughening treatment can reduce the surface roughness pitch (Sm) of the drum and reduce the surface roughness pitch (Sm) of the separator stack surface 17. This method can control the surface roughness pitch (Sm) of the surface in contact with the drum.

  Furthermore, the separator laminated surface 17 of the core body 4 is made to have a specific surface roughness pitch (Sm) even by a roughening process such as sandblasting in which fine particles are sprayed onto the surface of the core body 4 with air. It can be roughened. In the roughening treatment by sandblasting, the surface roughness pitch (Sm) is controlled by the particle size of the particles to be injected. This is because the average particle diameter of the particles can be reduced to reduce the surface roughness pitch (Sm). The roughening treatment by sandblasting can roughen the surface roughness pitch (Sm) of the separator laminated surface 17 provided on both surfaces of the core body 4. The core 4 of the electrolytic metal foil has a surface roughness pitch (Sm) of the contact surface with the drum roughened by the surface roughness of the drum, and a surface roughness pitch ( Sm) can be prepared to control the surface roughness pitch (Sm) of the separator laminate surface 17 provided on both sides.

  The positive electrode plate 1 </ b> A is provided with a positive electrode active material layer 5 on the surface of an aluminum foil that is a core body 4. In this electrode plate 1, the active material layer 5 is not provided on the outermost peripheral electrode plate 6, which is the winding end portion of the terminal portion. The end edge of the winding end portion of the core body 4 without the active material layer 5 is located at the curved corner portion 12 as shown in FIG. The positive electrode core 4 is provided with a folded piece 9 by cutting a part of the flat portion 11 on which the active material layer 5 is not provided. The folded piece 9 of the core body 4 is used as a lead for connecting the positive electrode plate 1 </ b> A to the exterior body 20. The electrode body 10 can electrically connect the positive electrode plate 1 </ b> A to the exterior body 20 stably in a low resistance state via the folded piece 9 of the core body 4. The flat portion 11 of the electrode plate 1 on which the folded piece 9 is provided is a core body 4 on which the active material layer 5 is not provided. For this reason, the folded piece 9 can connect the core body 4 directly to the exterior body 20 in a low-resistance state without using the active material layer 5. The electrode body 10 having the folded piece 9 is pressed to a predetermined thickness after the electrode body 10 wound in a spiral shape is bent, and the folded piece 9 is bent 180 degrees to be in a state where it can be used for a lead. When the spiral electrode body 10 is pressed, the folded piece 9 of the core body 4 is in the plane portion 11. The electrode body 10 can press the flat portion 11 of the outermost peripheral electrode plate 6 with the folded piece 9 into a flat shape with a uniform pressing force. As shown in FIG. 1, the folded piece 9 is sandwiched between the exterior body 20 and the sealing plate 21 and welded to the exterior body 20 and the sealing plate 21.

  The separator 3 is a microporous film made of plastic such as polypropylene. However, the separator 3 can be any separator that insulates the positive electrode and the negative electrode and allows the electrolyte and ions to pass therethrough. Therefore, although the nonwoven fabric which gathered the plastic fiber three-dimensionally and pressed into the sheet form can also be used for the separator 3, a microporous film is preferable when the adhesiveness with the core is taken into consideration.

  The electrode body 10 wound in a spiral shape is pressed so as to be sandwiched while being heated by pressing plates arranged in parallel with each other in a planar shape from both sides, and the opposing surfaces are formed into flat portions 11 parallel to each other. Process. The separator 3 is between the electrode plates 1 and insulates the electrode plates 1 stacked adjacent to each other. In the illustrated electrode assembly 10, the width of the separator 3 is wider than that of the electrode plate 1. The electrode body 10 can be reliably insulated by the separator 3 even if the winding position of the electrode plate 1 is slightly shifted.

  The electrode body 10 having a separator 3 stacked between a positive electrode plate 1A and a negative electrode plate 1B and wound in a spiral shape is pressed into a state in which a part of the electrode plate 1 is a flat portion 11. The pressed electrode plate 1 is in a state where both sides of the flat portion 11 to be laminated in parallel are connected to the curved corner portion 12. The flat portion 11 of the electrode plate 1 is laminated in parallel with the separator 3 interposed therebetween. The separator lamination surface 17 laminated in direct contact with the separator 3 is subjected to a roughening treatment so that the surface roughness pitch (Sm) is 50 μm or less. The separator lamination surface 17 is in close contact with the separator 3. The active material layer 5 is brought into close contact with the separator 3 on the surface of the electrode plate 1 that is not the separator lamination surface. Since the active material layer 5 has fine irregularities on the surface, the active material layer 5 has excellent adhesion to the separator 3.

  As shown in FIGS. 1 to 3, the electrode body 10 obtained by pressing a spirally wound material from both sides to have a predetermined thickness has the electrode plate 1 in the direction from the flat surface portion 11 to the curved corner portion 12. The structure is wound continuously. In the pressing process, the electrode body 10 is pressed from both sides so that the leading edge of the winding start portion and the terminal edge of the winding end portion are arranged in the curved corner portion 12. This is because the pressing force at the time of pressing is uniformly applied to the entire surface, and the flat portion 11 of the electrode plate 1 is processed into a predetermined thickness while being held flat. When the leading edge of the winding start part of the electrode plate and the terminal edge of the winding end part are in the middle of the flat part of the electrode body, the electrode plate is stepped at the flat part along the boundary line of the leading edge or terminal edge of the electrode plate. This is because it is pressed into a certain shape.

A spiral electrode square battery, which is a lithium ion secondary battery, is manufactured as follows.
[Preparation of positive electrode slurry]
As a positive electrode active material, LiCoO ₂ powder having an average particle diameter of 5 μm and artificial graphite powder as a positive electrode conductive agent are mixed at a mass ratio of 9: 1 to prepare a positive electrode mixture. This positive electrode mixture and a binder solution prepared by dissolving 5% by mass of polyvinylidene fluoride in N-methyl-2-pyrrolidone (NMP) are kneaded at a solid content mass ratio of 95: 5 to obtain a slurry for producing a positive electrode plate. To prepare.

[Preparation of positive electrode plate]
This slurry is applied to the aluminum foil (foil thickness: 15 μm) as the positive electrode core 4 using a doctor blade. The coating mass is 500 g / m ² (single-side coating 250 g / m ² , excluding current collector) as the mass after drying of the double-side coated part. After coating, the electrode plate is dried and pressed and compressed to produce an electrode plate having an active material packing density of 3.7 g / cc. Thereafter, the electrode plate is cut to fit the battery width and vacuum dried at 150 ° C. for 2 hours to obtain a positive electrode plate 1A.

[Production of negative electrode plate]
A flake shaped natural graphite (d ₀₀₂ value: 0.3356 nm, Lc value: 100 nm, average particle size: 20 μm) and a styrene-butadiene rubber (SBR) dispersion (solid content: 48%) were dispersed in water. Then, carboxymethyl cellulose (CMC) as a thickener is added to prepare a slurry. In addition, it prepares so that the solid content mass composition ratio after drying of this negative electrode may become graphite: SBR: CMC = 100: 3: 2. It apply | coats on both surfaces of copper foil (foil thickness: 10 micrometers) as a negative electrode collector so that it may become 200 g / m < ² > (single-sided application | coating 100g / m < ² >, collector is excluded) by mass after drying. Then, the electrode plate is dried and pressed and compressed to produce an electrode plate having an active material packing density of 1.7 g / cc. Thereafter, the electrode plate is cut to fit the battery width and vacuum dried at 110 ° C. for 2 hours to obtain a negative electrode plate 1B.

In the electrode body 10, the negative electrode plate 1 </ b> B is disposed at the center of the electrode body 10 as the innermost peripheral electrode plate 16. The winding start portion of the negative electrode has the flat portion 11 as the separator lamination surface 17 and the lead 15 is connected thereto. In the electrode body 10 shown in the cross-sectional view of FIG. 2, the winding start portion of the negative electrode plate 1 </ b> B is folded back with the U pole, and the opposing surface of the flat portion 11 is used as the separator lamination surface 17. The electrode body 10 shown in the figure has a separator separator surface 17 sandwiched between the separators 3. The separator lamination surface 17 is roughened so that the surface roughness pitch (Sm) has the following value.
Example 1... Surface roughness pitch (Sm) is 50 μm
Example 2 Surface roughness pitch (Sm) is 40 μm
Example 3 Surface roughness pitch (Sm) is 30 μm

[Electrolyte and separator]
As the non-aqueous electrolyte, a solution obtained by dissolving 1 mol / liter of LiPF ₆ in a mixed solvent of 50/50 volume ratio of ethylene carbonate (EC) and diethyl carbonate (DEC) is used. As the separator 3, a microporous film made of polypropylene is used.

[Production of electrode body]
After the positive electrode plate 1A and the negative electrode plate 1B obtained as described above and the separator 3 are wound in a spiral shape, the press surface is heated to 50 ° C. and applied with a surface pressure of 78 N / cm ^2. Press molding. The electrode body 10 manufactured in this state has a thickness of 4 mm, a vertical width that is the width of the separator 3 is 48 mm, and a horizontal width is 32 mm. In addition, the width | variety of the electrode plate 1 is narrower than the separator 3, and is 44 mm.

[Production of battery]
The above electrode body 10 is inserted into an outer can as the outer body 20 to obtain a square battery. The outer package 20 is a metal case made of aluminum or aluminum alloy whose inner shape is slightly larger than the outer shape of the electrode body 10. The exterior body 20 in which the electrode body 10 is inserted is closed by welding a sealing plate 21 to the opening. Thereafter, the electrolytic solution is injected into the exterior body 20 from the injection port provided in the sealing plate 21, and then the injection port is hermetically sealed.
Through the above steps, a square battery having a thickness of 5 mm, a width of 34 mm, and a height of 50 mm (design capacity: 1000 mAh) is manufactured.

Comparative example

  In order to demonstrate the excellent characteristics of the battery of the example, a square battery of a comparative example is prototyped. The battery of the comparative example is the same as the example except that the surface roughness pitch (Sm) of the separator laminate surface of the negative electrode plate is 60 μm (Comparative Example 1), 70 μm (Comparative Example 2), and 80 μm (Comparative Example 3). Produced in the same way.

[Thickening amount of electrode body after 1 hour of heating press]
As described above, 20 electrode bodies are manufactured in each of the examples and the comparative examples, and the expansion amount of the thickness of the electrode bodies is measured as follows.
Example 1 ... 20 µm to 50 µm
Example 2 ............ 0 μm to 20 μm
Example 3 ............ 0 μm to 20 μm
Comparative Example 1 ... 50 μm to 100 μm
Comparative Example 2 ... 80 to 150 [mu] m
Comparative Example 3 ... 100m to 200m

  From the above measurement results, it is clear that the electrode body 10 of the example of the present invention can have a very small expansion amount of 0 to 50 μm after 1 hour of hot pressing. On the other hand, the amount of swelling of the electrode body of the comparative example is extremely large, 50 μm to 200 μm.

[Battery thickness after charge / discharge cycle]
When the batteries of the example and the comparative example were subjected to 500 cycles of charge / discharge cycles by repeating full charge and complete discharge, the change in the thickness of the outer can was measured as a relative value based on the battery of the comparative example 1. It becomes as follows.
Example 1 ......- 50 μm to −150 μm
Example 2..., −200 μm to −350 μm
Example 3 ............- 200 μm to −350 μm
Comparative Example 2 ... 0 μm to +50 μm
Comparative Example 3 ......... + 150 μm to +200 μm

  From the above measurement results, in the battery of the example, the thickness of the outer can in the charge / discharge cycle is 50 μm to 350 μm thinner than that of Comparative Example 1. In contrast, the battery of Comparative Example 3 in which the surface roughness pitch (Sm) of the separator stack surface is 80 μm is 150 μm to 200 μm thicker than the battery of Comparative Example 1.

It is a partial cross section perspective view of the battery of the spiral electrode concerning one Example of this invention. FIG. 2 is an enlarged horizontal sectional view showing a central part of an electrode body of the battery shown in FIG. 1. It is a perspective view of the electrode body of the battery shown in FIG.

Explanation of symbols

1 ... Electrode plate 1A ... Electrode plate of positive electrode
DESCRIPTION OF SYMBOLS 1B ... Electrode plate of negative electrode 3 ... Separator 4 ... Core body 5 ... Active material layer 6 ... Outermost peripheral electrode plate 9 ... Folded piece 10 ... Electrode body 11 ... Planar part 12 ... Curved corner part 15 ... Lead 16 ... Innermost peripheral electrode Plate 17 ... Separator lamination surface 20 ... Exterior body 21 ... Sealing plate

Claims (6)

An electrode body (10) in which a positive electrode plate (1A) and a negative electrode plate (1B) are stacked and sandwiched with a separator (3) sandwiched between them makes a flat portion (11) on the electrode plate (1). A battery of spiral electrodes that is pressed into a housing (20),
The flat portion (11) of the electrode plate (1) has a separator lamination surface (17) in which the surface of the core (4) is in direct contact with the separator (3), and the separator of the electrode plate (1) The surface roughness pitch (Sm) of the laminated surface (17) is roughened to 50 μm or less, and the separator (3) is pressed directly on the surface of the separator laminated surface (17) and laminated directly. A battery with a spiral electrode.   The spiral type according to claim 1, wherein the core body (4) of the electrode plate (1) has a separator lamination surface (17) directly laminated on the separator (3) at the winding center portion of the electrode body (10). Electrode battery.   The battery of a spiral electrode according to claim 1, wherein both surfaces of the core body (4) of the electrode plate (1) are separator lamination surfaces (17).   2. The battery according to claim 1, wherein the battery is a lithium ion secondary battery, the core (4) of the electrode plate (1) having the separator lamination surface (17) is a metal foil, and the separator (3) is a plastic microporous film. A spiral electrode battery as described.   The battery of a spiral electrode according to claim 4, wherein the electrode plate (1) having the separator lamination surface (17) is a negative electrode of a lithium ion secondary battery, and the metal foil is a copper foil. The spiral electrode battery according to claim 1, wherein a lead (15) is connected to the separator lamination surface (17) of the electrode plate (1).

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