JP2003077543A - Flat nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat nonaqueous electrolyte secondary battery having a smaller size, superior heavy load property and higher discharge capacity. SOLUTION: The flat nonaqueous electrolyte secondary battery includes an electrode group consisting of a positive electrode 2, a negative electrode 4 and a separator 3 and a nonaqueous electrolyte in a negative electrode case 5 and a positive electrode case 1 in a sealed state. The electrode group is formed with the positive electrode, the negative electrode and the separator wound, having three or more faces opposed to the positive and negative electrodes in a cross section perpendicular to a flat plane, and a positive electrode constituent material and a negative electrode constituent material are exposed to the outside of the electrode group and connected to the positive electrode case and to the negative electrode case, respectively. The positive and negative electrodes and the separator, wound, are formed with a plurality of continued unit faces using a predetermined shape as one unit. As a result, larger area of the electrodes and the higher discharge capacity are achieved than those of a conventional one having straps wound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat type non-aqueous electrolyte secondary battery, and more particularly to a flat type non-aqueous electrolyte secondary battery having excellent heavy load characteristics and large discharge capacity.

[0002]

2. Description of the Related Art A lithium oxide such as lithium cobalt oxide, lithium nickel oxide, or lithium manganate is used as a positive electrode active material, and a carbonaceous material capable of inserting and extracting lithium into the negative electrode, or a lithium-containing tin oxide or lithium-containing material. A non-aqueous solvent such as propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethoxyethane, or γ-butyl lactone is used as an electrolyte using a lithium-containing oxide such as silicon oxide or lithium titanate. LiClO ₄ , LiPF ₆ , LiBF ₄ , L
_{iCF 3 SO 3, LiN (CF} 3 SO 2) 2, LiN
A lithium ion secondary battery using a non-aqueous electrolyte in which a supporting salt such as (C ₂ F ₅ SO ₂ ) ₂ is dissolved has already been put into practical use and is widely and commonly used as a main power source for mobile phones and notebook PCs. There is.

In recent years, with the miniaturization of the equipment used, it has been required that the secondary battery be further miniaturized, and in response to this, the present inventors have responded to the flat non-aqueous electrolyte secondary battery. The positive and negative electrode facing surfaces (the surface where the positive electrode and the negative electrode face each other via the separator) are at least three or more in a cross section perpendicular to the flat surface, and the total area of the positive and negative electrode facing surfaces is the opening of the insulating gasket. A secondary battery having a larger area has been developed (Japanese Patent Laid-Open Nos. 2001-068160 and 2001-068143).
issue). For example, a positive electrode and a negative electrode may be laminated with a separator to have three or more positive and negative electrode facing surfaces, or a positive electrode and a negative electrode may be wound with a separator to have three or more positive and negative electrode facing surfaces. is there.

In these batteries, conductive positive electrode constituents and negative electrode constituents are exposed in the horizontal direction at the outermost side of the battery group, and these are in direct contact with the positive electrode case and the negative electrode case. Current collection is done. Therefore, as a current collecting structure, like a cylindrical battery, a tab terminal is taken out from the center of the electrode group, and this is complicatedly bent and welded to a safety element, a sealing pin, a battery can, or the like. It has the advantages of low complexity and good workability.

[0005]

The flat type non-aqueous electrolyte secondary battery having three or more positive and negative electrode facing surfaces has a heavy load characteristic as compared with a conventional battery of the same type using a tablet-shaped electrode. Was able to improve dramatically. However, it is undeniable that the battery has a small discharge capacity as compared with the conventional cylindrical or prismatic lithium secondary battery, and thus the discharge capacity is small.

The present invention has been made to solve the above problems, and is intended to increase the discharge capacity to the limit while maintaining the small size, that is, the small size and the excellent heavy load characteristics. It is also an object of the present invention to provide a flat non-aqueous electrolyte secondary battery having a large discharge capacity.

[0007]

In order to increase the capacity of the flat battery, the present inventors have tried to minimize the space occupied by the electrode group and utilize the volume effectively. For example, in the laminated type electrode group proposed in Japanese Patent Laid-Open No. 2001-068160, the current-carrying parts of a plurality of thin electrodes are integrated by welding, and the volume occupied by the current-carrying parts is large, so the space inside the battery is effectively used. Can not. Especially when the total battery height was increased to obtain a battery with a large discharge capacity, it was difficult to effectively use the space inside the battery because the current-carrying part connecting the plurality of electrodes had to be long. .

On the other hand, in the case of the wound electrode group proposed in Japanese Patent Laid-Open No. 2001-068143, it is not necessary to provide the current-carrying portion in a space other than the electrode coated with the active substance layer, and there is room for increasing the capacity. is there. However, since the rectangular electrode is wound to form the electrode group, the shape of the electrode group in the flat plane direction of the battery becomes square. For example, in the case of a circular flat battery, the planar shape of the electrode group is a circular battery case. Alternatively, it is inevitable that the gasket is inscribed in a square or a rectangle, and as a result, a space is formed around the electrode group. It was not possible to make effective use of this space.

As a result of repeated studies focusing on this point, the inventors of the present invention have determined that the shape of the wound electrode is not rectangular, but that the shape conforming to the flat shape of the battery is defined as one unit, and a plurality of such shapes are connected in series. By adopting the different shape, the planar shape of the wound electrode group is adapted to the shape of the battery, and the space inside the battery is effectively used to solve this problem.

That is, according to the present invention, a metal negative electrode case also serving as a negative electrode terminal and a metal positive electrode case also serving as a positive electrode terminal are fitted and sealed via an insulating gasket, and the positive electrode, the separator and the negative electrode are housed therein. A positive electrode constituent member and a negative electrode constituent member that include a group of electrodes and a non-aqueous electrolyte, and the positive and negative electrode facing surfaces of the electrode unit are three or more in a cross section perpendicular to a flat surface, and have conductivity on the outermost side of the electrode group. In the flat non-aqueous electrolyte secondary battery exposed to be connected to the positive electrode case and the negative electrode case, respectively, the electrode group, a positive electrode having a shape in which a plurality of unit surfaces having a predetermined shape as one unit, are connected, a separator And the negative electrode is wound.

The above-mentioned one unit shape is, for example, a polygon such as a hexagon or an octagon, a circle, an ellipse, etc. In the case of a circle or an ellipse, the connecting portion of each unit surface is an arc. It is better to avoid it so that it has at least two edges around it. When such a unit surface having a continuous shape is wound, the shape of the electrode group is similar to that of the battery case and the gasket when the shape of the electrode group is viewed from the upper surface of the flat surface of the battery. As a result, most of the space in the battery can be filled with the electrode constituent material, and the discharge capacity is dramatically increased compared to the conventional case.

For example, comparing the conventional square inscribed in a circle with the polygon of the present invention, the electrode area is 1.3 with the square being 1 for an inscribed regular hexagon and 1.4 for an inscribed regular octagon. In the case of a circle or an ellipse, if the two sides are cut off by a straight line as described above, it becomes about 1.5 or more. The shape of the unit surface is not limited to the above shape, and can be arbitrarily selected according to the shape of a flat battery having a special shape such as an oval shape.

According to the present invention, the discharge capacity can be increased by increasing the area of the horizontal surface of the electrode group in this way, but the following problems occur when the electrodes are wound. That is, due to the difference in circumferential length between the inner circumference and the outer circumference of the electrode due to winding, positional deviation or wrinkles of the positive and negative electrodes and the separator occur in the winding direction of the electrode group, resulting in a semi-short circuit during charging or charging. Problems such as deterioration of discharge cycle characteristics occur.

To solve this problem, the center interval of the connected unit surfaces is made shorter for the inner circumference of the winding and longer for the outer circumference of the winding. By making such a correction in advance, it is possible to prevent the electrode from being bent or displaced due to the difference between the inner and outer circumferences during winding, or the active material layer from falling off.

This is particularly important at the winding peripheral portion of the electrode. Since the battery of the present invention has a structure in which the upper and lower surfaces of the flatly wound electrode group are applied to the battery case to carry out the energization treatment, a slight deviation of the winding end portions of the positive and negative electrodes may result in improper energization or internal short circuit. This is because it will occur. In a conventional battery in which strip-shaped electrodes are wound, the electrode end is protected by a winding tape and insulated from the battery case to prevent some deviation, but in the case of the present invention, the electrode shape is complicated. In addition, since the battery case is spread over the entire shape of the battery case, it is a very important technique to stabilize the position and shape of the winding periphery of the electrode.

Furthermore, the present inventors have found that it is preferable to devise an electrode so that when connecting the unit surfaces of the electrodes, a very short strip-shaped intermediate region is provided between adjacent unit surfaces, and this is used as a connecting portion. . That is, as described above, when the center distance between the unit surfaces is made longer toward the outer peripheral side, for example, when the unit surface is a circle, since the circles have the same radius, the width of the connecting portion becomes narrower toward the outer peripheral side. . Therefore, the strength of the unit surface connecting portion on the outer peripheral side is reduced, and this portion is broken due to the stress due to the tension and contraction of the electrode during repeated charge and discharge cycles.

As a measure for improving this, if a strip-shaped connecting portion is provided as described above, this portion is reinforced and the electrode strength is improved. In order to prevent electrode breakage during winding and electrode breakage due to charge / discharge cycles, it is desirable to optimize the width of the connecting part.
It has been found that it is preferable to satisfy (1). B / A ≧ 0.15 (1)

Here, A is the maximum width of the unit surface in the direction perpendicular to the winding direction, and B is the width of the connecting portion in the direction perpendicular to the winding direction. When the B / A value is less than 0.15, the strength of the connecting portion becomes weak, and the electrode breaks when the battery is assembled or the charge / discharge cycle is repeated. Further, it is more preferable to set it in the range of the following formula (2), because it is possible to eliminate the breakage failure of the electrode. B / A ≧ 0.2 (2)

Further, from the viewpoint of taking the discharge capacity as large as possible, the B / A value is preferably within the range of the following formula (3). B / A ≦ 0.7 (3)

When the B / A value is larger than 0.7, the connecting portion hits the gasket, and in order to avoid this, it is necessary to reduce the size of the unit surface to reduce the distance between the unit surfaces. Then, the electrode area is reduced and the discharge capacity is reduced.

When the B / A value is within the range of the following formula (4), the discharge capacity can be increased to the limit, which is preferable. B / A ≦ 0.6 (4)

In the actual production of the battery of the present invention, it is preferable to cut or punch electrodes or separators into a desired shape in advance and then wind the electrodes to form an electrode group, but the productivity is increased. Therefore, cutting or punching may be performed after winding.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) FIG. 1 is a sectional view of a battery of this embodiment in a direction perpendicular to a flat surface, FIG. 2 is a sectional view in a horizontal direction of a flat surface, and a schematic view of a positive electrode plate used. Figure 3 and Figure 3
FIG. 4 shows an enlarged view of the outermost peripheral portion in FIG.

Next, a method for manufacturing the battery of this embodiment will be described. First, with respect to 100 parts by mass of LiCoO ₂ , 5 parts by mass of acetylene black and 5 parts by mass of graphite powder were added as a conductive agent, 5 parts by mass of polyvinylidene fluoride was added as a binder, diluted with N-methylpyrrolidone, and mixed. To obtain a slurry-like positive electrode mixture. Next, this positive electrode mixture was applied on both sides of a 0.02 mm-thick aluminum foil, which is a positive electrode current collector, by the doctor blade method, dried, and then rolled so that the electrode thickness would be 0.12 mm. . Then 17.7 from the edge of one side
The positive electrode mixture coated up to the area of mm was removed to expose the aluminum foil, which was used as a current collector.

The electrode thus obtained was cut into the shape shown in FIG. The detailed shape of this positive electrode plate 2 is a shape in which eight circular circular unit surfaces having a diameter of 18 mm are arranged in eight rows, and the positive electrode mixture is one surface on the outermost unit surface when wound together with the negative electrode and the separator. The removed aluminum foil is exposed to form the positive electrode current collector 2a.

As shown in FIG. 3, when the circular unit surfaces are lined up, the center distance between the unit surfaces is 18.1 mm on the outer peripheral side of the winding (left side in the drawing) and on the winding core side (right side in the drawing). Was set to 15.4 mm, and gradually became shorter toward the core side. The width of the connecting part that connects the unit faces is the narrowest on the outer peripheral side, 6m
m. An enlarged view of this portion is shown in FIG. The total length of the positive electrode plate 2 is 133.7 mm, and the total area of the active substance-containing layer applied is 37.1 cm ^{2 on} both front and back sides.

Next, preparation of the negative electrode mixture will be described. To 100 parts by mass of graphitized mesophase pitch carbon fiber powder, 2.5 parts by mass of styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were added as binders, respectively, diluted with ion-exchanged water and mixed to prepare a slurry negative electrode mixture. I got an agent. This negative electrode mixture is a negative electrode current collector with a thickness of 0.
After coating on both sides of 02mm copper foil and drying, the electrode thickness is 0.12
Then, the negative electrode mixture applied to the portion 17.7 mm from the edge of one surface was removed to expose the copper foil, and the copper foil was exposed to form a current collecting portion, as in the case of the positive electrode.

The electrode thus obtained has a circular unit surface with a diameter of 18.5 mm, and the connecting width between the unit surfaces is greater than that of the positive electrode.
It was widened by 0.5 mm, and was otherwise cut out in the same manner as in the case of the positive electrode to obtain a negative electrode plate 4. The reason why the area of the negative electrode plate is made slightly larger than the area of the positive electrode plate is to prevent the deposition of metallic lithium during charging and to obtain good charge / discharge cycle characteristics.

Next, a separator made of a polyethylene microporous film having a thickness of 25 μm was cut into a shape corresponding to the length of two electrodes. Also in this separator, the unit surface distance of the winding outer peripheral portion is long, and the unit surface distance of the winding core portion is short. In addition,
In order to prevent an internal short circuit, the diameter of the unit surface of the separator was set to 20 mm, and the connection width was made wider by 2 mm than that of the positive electrode plate, which was one size larger than that of the negative electrode plate.

A flat wound electrode group was produced using the positive and negative electrode plates and the separator thus obtained. First, the center portion of the separator 3 was aligned with the end of the positive electrode plate 2 on the winding core side and folded back, and the positive electrode plate 2 was wrapped in the separator 3. Then, the negative electrode plate 4 is arranged so that the unit surfaces on the winding core side overlap each other.
And were wound in a flat shape while stacking these, and the ends of the positive and negative electrode plates were fixed with a winding tape 7 in which an adhesive was applied to polypropylene, to obtain an electrode group. At this time, it is wound so that both the positive and negative electrode current collectors are exposed at the outermost periphery.

After the manufactured electrode group was dried at 85 ° C. for 12 hours, it was placed so that the negative electrode current collector was in contact with the negative electrode metal case 5 having a 0.1 mm thick stainless net 8 welded to the bottom surface, and ethylene carbonate and γ were added. -Butyl lactone was mixed in a volume ratio of 1: 2, and LiBF was used as a supporting salt in a solvent.
A non-aqueous electrolyte prepared by dissolving ₄ in a ratio of 1.5 mol / l was injected. Further, an aluminum net 9 was welded to the bottom surface of a positive electrode case 1 made of stainless steel whose inner surface was covered with aluminum. After fitting upside down, the negative electrode case 5 was pressed in a direction perpendicular to the flat surface of the battery, While crimping the electrode group inside the battery, the positive electrode case 1 is caulked, and the thickness is 3 mm and the diameter is 24.
A 5 mm flat non-aqueous electrolyte secondary battery was produced.

Example 2 A positive electrode plate having a regular octagonal unit surface shown in FIG. 6 was used. This is diameter 18
It has a shape in which regular octagons inscribed in a circle of mm are connected, and the center interval of the connected unit surfaces is the same as that in the first embodiment. The total coated area of the active substance-containing layer of this positive electrode plate is 34.3 cm ² on both front and back surfaces.

Similarly, a negative electrode having a shape in which a regular octagon inscribed in a circle having a diameter of 18.5 mm is connected, and a separator having a shape in which a regular octagon inscribed in a circle having a diameter of 20 mm are connected are prepared. A flat non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1. FIG. 5 shows a sectional view of this battery in a direction horizontal to the flat surface.

(Comparative Example 1) The electrode plate was not in the continuous shape of the unit surface as in each of the above-mentioned Examples, but in the strip shape as in the conventional case. That is, as shown in FIG.
12.5 mm, length 101.9 mm, strip-shaped electrode with active substance-containing layer removed portion (positive electrode current collector 2a) length of 13.8 mm, total coated area of active substance-containing layer is 23.8 cm ² on both front and back sides A plate was used as the positive electrode plate 2, and similarly, a strip-shaped negative electrode plate 4 having an electrode width of 13 mm and a strip-shaped separator 3 having a width of 15 mm were used to wind these into an electrode group. A battery was produced in the same manner as in Example 1 except for the above. FIG. 7 shows a sectional view of the battery of Comparative Example 1 in the direction perpendicular to the flat surface, and FIG. 8 shows a sectional view in the direction horizontal to the flat surface.

The batteries of Example 1, Example 2 and Comparative Example 1 produced as described above were initially charged for 48 hours at a constant current and a constant voltage of 4.2 V and 5 mA. After that, discharge was carried out at a constant current of 50 mA to 3.0 V to obtain the discharge capacity.
This is shown in Table 1. Further, the improvement ratio (%) was obtained by comparing the discharge capacities of Example 1 and Example 2 with the discharge capacity of Comparative Example 1. The results are also shown in Table 1.

[0036]

[Table 1]

As shown in Table 1, the batteries of Example 1 and the battery of Example 2 had significantly larger discharge capacities than the battery of Comparative Example 1, and the use of electrodes having a shape in which unit faces were connected to each other It can be seen that the discharge capacity is greatly improved.

Next, the connecting widths of the unit surfaces were variously changed and the influence thereof was examined. (Examples 3 to 8) Using a positive electrode plate having a shape in which circular unit surfaces are connected, the connecting width (B) of the connecting portion of the unit surface which is the outer side when wound is 2.0 mm as shown in Table 2. From 15.0m
It was changed to m. The width of the unit surface (A) is 18.0m
m. As in Example 1, the negative electrode plate and the separator were made one size larger than the positive electrode plate. A flat non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 except for the above. In addition,
In the batteries of Examples 6 to 8, in order to prevent the connecting portion of the electrode and the separator from coming into contact with the gasket, the positive electrode plate unit surface center distance of the outer peripheral portion was set as shown in Table 2. Also,
The unit surface center distance between the negative electrode plate and the separator was also changed according to the positive electrode plate.

The discharge capacities of the batteries of Examples 3 to 8 produced as described above were determined by the method described above. The obtained discharge capacity and the improvement rate of the discharge capacity with respect to Comparative Example 1 are shown in Table 2.
Shown in.

[0040]

[Table 2]

As shown in Table 2, Examples 1, 3 to 8
Battery has a larger discharge capacity than the battery of Comparative Example 1,
In particular, the battery having a ratio B / A of the maximum width A of the unit surface to the width B of the connecting portion of 0.7 or less was excellent in discharge capacity, and was more excellent when the ratio B / A was 0.6 or less.

Next, 100 batteries of each of Example 1 and Examples 3 to 8 were produced and initially charged for 48 hours at a constant current and a constant voltage of 4.2V and 5 mA. Next, a charge / discharge cycle test was performed in which the battery was discharged to a constant current of 50 mA to 3.0 V and then charged to a constant current and constant voltage of 4.2 V and 50 mA for 3 hours. The test was carried out up to 200 cycles, but during the test, some batteries were found to have a sharp decrease in charge / discharge capacity. As a result of disassembling and examining the battery after 200 cycles, the battery with reduced charge / discharge capacity had electrode breakage at the connecting portion on the outer peripheral side of the electrode, and electrical continuity with the center of the wound electrode was lost.

Table 2 shows the rate of occurrence of electrode breakage defects. The battery of Example 3 having a B / A value of less than 0.15 had a high defect occurrence rate of 8%, and the B / A value of exceeding 0.15.
The number of defective batteries was as small as 3%. B / A value is 0.
When it was 2 or more, no defects occurred at all as seen in the batteries of Example 1 and Examples 5-8.

In each of the above embodiments, the flat non-aqueous electrolyte secondary battery using the non-aqueous solvent as the non-aqueous electrolyte has been described.
It is also applicable to a polymer secondary battery using a polymer electrolyte as a non-aqueous electrolyte and a solid electrolyte secondary battery using a solid electrolyte. It is also possible to use a polymer thin film or a solid electrolyte membrane instead of the resin separator. Further, regarding the battery shape, the coin-shaped battery which is sealed by crimping the positive electrode case has been described, but it may be one which is crimped by the negative electrode case, and the shape is not limited to the coin shape, and a part of the R shape is used. It may be a flat shape having a special shape such as an oval shape or an oval shape.

In the above embodiments, lithium cobalt oxide was used as the positive electrode acting substance and carbonaceous material was used as the negative electrode acting substance, but the present invention is not limited to these.
It is also applicable to batteries using other positive and negative electrode acting substances.

[0046]

As described above, according to the present invention, as a result of further improvements made to the flat type non-aqueous electrolyte secondary battery which has been improved so far, the battery size is very small and the discharge capacity is large, and It is possible to provide a flat non-aqueous electrolyte secondary battery having excellent cycle characteristics.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a battery of Example 1 in a direction perpendicular to a flat surface.

FIG. 2 is a sectional view of the battery of Example 1 in a direction horizontal to a flat surface.

3 is a top view of the positive electrode plate used in the battery of Example 1. FIG.

FIG. 4 is an enlarged view of the outermost peripheral portion of the positive electrode plate used in the battery of Example 1.

FIG. 5 is a cross-sectional view of the battery of Example 2 in a direction horizontal to the flat surface.

6 is a top view of the positive electrode plate used in the battery of Example 2. FIG.

7 is a cross-sectional view of the battery of Comparative Example 1 in a direction perpendicular to the flat surface.

8 is a cross-sectional view of the battery of Comparative Example 1 in a direction horizontal to the flat surface.

9 is a top view of the positive electrode plate used in the battery of Comparative Example 1. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Positive electrode case, 2 ... Positive electrode plate, 2a ... Positive electrode current collecting part, 2b
... Positive electrode active substance-containing layer coating part, 3 ... Separator, 4 ... Negative electrode plate, 4a ... Negative electrode current collecting part, 4b ... Negative electrode active substance containing layer coating part, 5 ... Negative electrode case, 6 ... Insulating gasket, 7 ... Winding Stopping tape, 8 ... Stainless steel net, 9 ... Aluminum net, 10 ... Electrode group.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuichi Kikuma             3-4-10 Minami-Shinagawa, Shinagawa-ku, Tokyo Toshiba             Battery Co., Ltd. F-term (reference) 5H011 AA03 CC06 GG02 JJ02                 5H022 AA09 AA18 BB01 CC08 CC21                       EE01 EE04                 5H029 AJ03 AJ05 AK03 AL03 AL06                       AM02 AM03 AM05 AM07 BJ03                       BJ14 CJ07 DJ02 DJ03 DJ05                       EJ04 EJ12 HJ04                 5H050 AA07 AA08 BA17 CA08 CA09                       CB03 CB07 EA10 EA23 EA24                       FA05 GA09 HA04

Claims (8)

[Claims] 1. A metal negative electrode case which also serves as a negative electrode terminal and a metal positive electrode case which also serves as a positive electrode terminal are fitted and sealed with an insulating gasket interposed therebetween, and an electrode group including a positive electrode, a separator and a negative electrode therein. And a non-aqueous electrolyte are included, and the positive and negative electrode facing surfaces of the electrode group are three or more in a cross section perpendicular to the flat surface, and the positive electrode constituent material and the negative electrode constituent material having conductivity are exposed on the outermost side of the electrode group. In the flat nonaqueous electrolyte secondary battery connected to the positive electrode case and the negative electrode case, respectively, the electrode group includes a positive electrode, a separator, and a negative electrode having a shape in which a plurality of unit surfaces each having a predetermined shape as one unit are connected. A flat non-aqueous electrolyte secondary battery, which is configured by being wound. 2. A unit surface having a predetermined shape as one unit,
The flat non-aqueous electrolyte secondary battery according to claim 1, wherein the flat non-aqueous electrolyte secondary battery is a circle, an ellipse, or a polygon, and a connecting portion between the unit surfaces is linear. 3. The flat non-aqueous electrolyte secondary battery according to claim 1, wherein the unit surfaces are connected to each other by a belt-shaped connecting portion. 4. The flat type according to claim 1, wherein the unit surfaces are connected such that the center-to-center distance between the connected unit surfaces is shorter on the core side when wound than on the outer peripheral side. Non-aqueous electrolyte secondary battery. 5. The maximum unit surface width A in the direction perpendicular to the winding direction is defined by the unit surface located on the outer circumference of the electrode and its connecting portion.
The flat type non-aqueous electrolyte secondary battery according to claim 1, wherein B and A have a relationship of B / A ≧ 0.15. 6. The flat non-aqueous electrolyte secondary battery according to claim 5, which has a relationship of B / A ≧ 0.2. 7. The maximum unit surface width A in the direction perpendicular to the winding direction is defined by the unit surface located on the outer circumference of the electrode and its connecting portion.
The width B of the connecting portion has a relationship of B / A ≦ 0.7.
The flat non-aqueous electrolyte secondary battery described. 8. The flat non-aqueous electrolyte secondary battery according to claim 7, which has a relationship of B / A ≦ 0.6.