JP2011233408A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery which has improved discharge load characteristics and charge discharge cycle characteristics which normally deteriorate when a sectionally oval shaped electrode body is formed, thereby providing superior reliability against dropping.SOLUTION: A nonaqueous electrolyte secondary battery comprises an electrode body which has wound around it via a separator having micropores a cathode and an anode each consisting of an active material layer formed on a metal foil, the electrode body being accommodated in an outer container. In this battery, the electrode body is oval shaped in cross section, a straight part on one side thereof consisting of the cathode, the separator, and the anode which are stratified in order from the periphery toward the center of winding, a curved part on one side thereof consisting of the cathode, an insulating member to protect the electrode plate, the separator, and the terminal of the anode which are stratified in order, a straight part on the other side thereof consisting of the cathode, the separator, the cathode, the separator, and the anode which are stratified in order, and a curved part on the other side thereof consisting of the terminal of the cathode, the terminal of the separator, the cathode, the separator, and the anode which are stratified in order.

Description

  The present invention relates to a non-aqueous electrolyte secondary battery.

  Non-aqueous electrolyte secondary batteries typified by lithium-ion batteries are characterized by high energy density, so they can be used not only for power supplies for portable devices, but also for power tools and hybrid electric vehicles. I am doing.

  In such a non-aqueous electrolyte secondary battery, a lithium transition metal oxide such as lithium cobaltate, lithium nickelate, or lithium manganate capable of reversibly occluding and releasing lithium ions is used as a positive electrode active material. The positive electrode active material is mixed with a binder, a conductive agent, and the like, applied on an aluminum foil as a positive electrode core, and used as a positive electrode plate.

  On the other hand, as the negative electrode active material, carbonaceous materials such as natural graphite, artificial graphite and coke are used. And a negative electrode active material is mixed with a binder etc., and it apply | coated on the copper foil as a negative electrode core, and is used as a negative electrode plate.

  The positive electrode plate and the negative electrode plate are processed to a predetermined size, wound up through a resin microporous separator such as polyethylene to form an electrode body, and enclosed in an outer container together with an electrolyte.

  Each of the positive electrode plate and the negative electrode plate of the electrode body includes a current collecting tab, and the current collecting tab is connected to an external electrode. As the shape of the current collecting tab, for example, as shown in Patent Document 1 and FIG. 6, an aluminum foil is arranged on the outermost periphery of the electrode body, and a notch is cut out in a U-shape on a part of the aluminum foil. There are things that fold back at the base of the U-shaped and become current collecting tabs. In this case, the electrode body is configured so that the lower layer of the aluminum foil provided with the cutout is also an aluminum foil so that the current collecting tab cut out of the aluminum foil and the negative electrode portion are not short-circuited.

  With the increase in functionality and miniaturization of portable devices found in recent years, batteries as power sources for these devices are required to have higher energy density and safety. As a technique for increasing the energy density, there is a method of increasing the amount of active material charged in the battery. In this method, in order to charge a large amount of active material into the limited internal volume of the outer container, the active material applied to the electrode plate core is compressed to a high density, and the filling density is increased.

  On the other hand, in batteries such as Patent Documents 2 to 4, in order to efficiently store the electrode body in the outer container, the electrode body is molded by applying pressure using a press machine or the like.

  Regarding the safety of the battery, as in Patent Document 5, when the active material application part of the negative electrode and the aluminum foil exposed part of the positive electrode are separated by an insulating member, the damage increases when an internal short circuit occurs in the part. However, a technique for preventing the occurrence of an internal short circuit by this means and improving the safety of the battery is disclosed.

Japanese Patent Laid-Open No. 09-171809 JP 2002-289257 A JP-A-2005-347125 JP 2005-327550 A JP 2004-259625 A

  While the above-described high energy density technique has made it possible to increase the capacity of the battery, there has been a problem in that the discharge characteristics at high loads and the charge / discharge cycle characteristics deteriorated. Moreover, although the safety | security with respect to an internal short circuit improved by the method for improving the above-mentioned safety | security, when the battery was dropped, it turned out that a short circuit still occurs. When the inventors investigated the cause of this, the following became clear.

  That is, regarding the deterioration of the battery characteristics, in order to store the electrode body in the outer container as described above, the electrode body is molded by applying pressure, but when the packing density of the electrode plate is not high, the powder particles Since the electrode plate, which is an assembly of the above, also has flexibility, pressure is absorbed by the electrode plate, so that the pores of the separator are prevented from being excessively crushed by the molding pressure.

  However, when the packing density of the electrode plate increases, the flexibility of the electrode plate is lost, and molding pressure is applied to the separator. As a result, it was found that the pores of the separator were excessively crushed, the lithium ion passage was blocked, and the discharge characteristics and charge / discharge cycle characteristics of the battery deteriorated.

  In addition, regarding the safety of dropping the battery, an insulating member is attached to the periphery of the negative electrode terminal on the outer periphery side of the electrode body to prevent a short circuit. The electrode body of the prismatic battery has an oval cross section, and the negative electrode terminal is located at one of two oval curved portions. The curved part of the electrode body is a part that is easily deformed due to a drop impact when the battery is dropped, and the insulating member described above is attached to the vicinity of one curved part where the negative electrode terminal exists. The insulating member also has a role of preventing deformation of the electrode body curved portion due to a drop impact. On the other hand, it has been found that the other curved portion having no deformed negative electrode end does not have an insulating member like the one curved portion, and is easily deformed by a drop impact to cause a short circuit.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a non-aqueous electrolyte secondary battery having high capacity and improving discharge characteristics, charge / discharge cycle characteristics, and safety. It is in.

  In order to solve the above-described problem, the nonaqueous electrolyte secondary battery according to the first aspect of the present invention includes an electrode body in which a positive electrode and a negative electrode are wound via a microporous separator in an outer container. The electrode body has a cross-section of a pair of straight portions including one straight portion and the other straight portion, one end of the one straight portion, and the other An ellipse comprising one curved portion connecting one end of the straight portion, the other curved portion connecting the other end of the one immediately preceding portion and the other end of the other straight portion, the positive electrode, the negative electrode, The separator is wound in the order of the one straight portion, the one curved portion, the other straight portion, and the other curved portion, and the one straight portion is directed from the outer periphery toward the winding center. The positive electrode, the separator, and the negative electrode are sequentially layered, and the one curved portion extends from the outer periphery to the winding center. Thus, the positive electrode, the insulating member that protects the electrode plate, the separator, and the terminal end of the negative electrode sequentially form a layer, and the other straight portion is formed in order of the positive electrode, the separator, the positive electrode, the separator, and the negative electrode from the outer periphery toward the winding center. A layer is formed, and the other curved portion is characterized in that the terminal of the positive electrode, the terminal of the separator, the positive electrode, the separator, and the negative electrode are sequentially formed from the outer periphery toward the winding center.

  Furthermore, the nonaqueous electrolyte secondary battery according to the second aspect of the present invention is the nonaqueous electrolyte secondary battery according to the first aspect, wherein the other straight portion is made of a metal foil from the outer periphery toward the winding center. It is characterized in that layers are formed in the order of a positive electrode, a separator, a positive electrode whose outer peripheral side is a metal foil, a separator, and a negative electrode.

  Furthermore, the nonaqueous electrolyte secondary battery according to the third aspect of the present invention is the nonaqueous electrolyte secondary battery according to the first or second aspect, wherein the end of the other curved separator is the end of the two-layer separator. It is characterized by being.

  Furthermore, the nonaqueous electrolyte secondary battery according to the fourth aspect of the present invention is the nonaqueous electrolyte secondary battery according to any one of the first to third aspects. It is characterized by covering more than half of the music part.

  According to the first aspect of the present invention, the separator in the lower layer on the positive electrode on the outer periphery plays the role of a cushion that absorbs the pressure at the time of molding the electrode body in the other straight line portion of the oval cross section of the electrode body. An excessive pressure is prevented from being applied to the separator located in the center of the electrode body rather than the separator. Therefore, it is possible to increase the battery capacity by setting the electrode to a high packing density, and the micropores of the separator are not easily crushed, a lithium ion path is secured, and the battery characteristics are improved. Furthermore, since the separator having the role of a cushion is extended to the curved portion and terminates at the lower end of the positive electrode on the other straight line portion of the other oval cross section of the electrode body, the separator is deformed by the drop impact. To prevent. Therefore, short circuits due to battery dropping are reduced.

  According to the second aspect of the present invention, when the outer peripheral positive electrode is a metal foil and the outer peripheral side of the lower positive electrode is a metal foil, the metal foil does not absorb the pressing pressure at the time of molding the electrode body. When the separator is arranged as in the configuration of the aspect, the effect is more preferable and preferable.

  According to the third aspect of the present invention, in the nonaqueous electrolyte secondary battery according to the first or second aspect, since there are two layers of the separator in the lower layer on the outer peripheral positive electrode, the electrode body is molded. Therefore, it is possible to more effectively prevent an excessive pressure from being applied to the separator located in the center of the electrode body than these separators. Therefore, since the electrode has a high packing density, the battery capacity is high, the micropores of the separator are not easily crushed, a lithium ion passage is secured, and the battery characteristics are favorable, which is preferable. In addition, since the two layers of separators, which serve as cushions in the lower layer of the outer peripheral positive electrode in the other straight part having an elliptical cross section of the electrode body, are both extended to the curved portion and terminated, the electrode body due to drop impact Can be effectively prevented. Therefore, the short circuit due to the dropping of the battery is reduced, which is preferable.

  According to the fourth aspect of the present invention, since the end of the separator disposed in the other curved portion covers more than 1/2 of the curved portion, the majority of the curved portion is placed on the separator located in the outer peripheral positive electrode lower layer. This is preferable because the separator is more effectively prevented from being deformed by a drop impact.

It is a longitudinal cross-sectional view of the nonaqueous electrolyte secondary battery which concerns on this invention. 1 is a cross-sectional view of an electrode body of a nonaqueous electrolyte secondary battery according to Example 1. FIG. 4 is a cross-sectional view of an electrode body of a nonaqueous electrolyte secondary battery according to Example 2. FIG. 6 is a cross-sectional view of an electrode body of a nonaqueous electrolyte secondary battery according to Example 3. FIG. It is electrode body sectional drawing of the nonaqueous electrolyte secondary battery which concerns on a comparative example. It is a figure which shows the structure of the battery which produced the positive electrode current collection tab using the outer periphery positive electrode metal foil.

  A mode for carrying out the present invention will be described with reference to the drawings, taking a non-aqueous electrolyte secondary battery as an example. In addition, this invention is not limited to the following form, In the range which does not change the summary, it can change suitably and can implement.

  FIG. 1 is a longitudinal sectional view of a nonaqueous electrolyte secondary battery according to the present invention. 2 to 5 are cross-sectional views of electrode bodies of nonaqueous electrolyte secondary batteries according to Examples 1 to 3 and a comparative example. FIG. 6 is a view showing the structure of the positive electrode current collecting tab.

[Embodiment]
As shown in FIG. 1, the nonaqueous electrolyte secondary battery 10 of the example is made of an aluminum alloy together with an electrolytic solution in which an electrode body 14 in which a positive electrode plate 11 and a negative electrode plate 12 are spirally wound through a separator 13. It is stored in a rectangular bottomed outer container 15. A negative electrode current collecting tab 19 is led out from the negative electrode plate 12 and connected to the negative electrode terminal 18 of the sealing lid 16. As shown in FIG. 6, a portion where the aluminum foil core body of the positive electrode plate 11 is exposed is disposed on the outer periphery of the electrode body, and the positive electrode current collecting tab 20 is disposed. The positive electrode current collecting tab is formed by cutting an aluminum foil core into a U-shape and turning the cut back to form a positive electrode current collecting tab. The positive electrode current collecting tab is sandwiched between gaps between the sealing lid 16 and the opening of the outer container 15 and is laser-welded together with the sealing lid 16 and the outer container 15 opening.

  The method for producing the non-aqueous electrolyte secondary battery is as follows.

<Preparation of positive electrode plate>
95 parts by mass of lithium cobaltate (LiCoO ₂ ) and 5 parts by mass of a carbon material as a conductive agent are mixed, and 95 parts by mass of this mixture and 5 parts by mass of polyvinylidene fluoride as a binder are mixed with N-methyl-2- A positive electrode mixture slurry was prepared by dispersing in pyrrolidone (NMP). This slurry was uniformly applied to both surfaces of an aluminum foil having a thickness of 15 μm by a doctor blade method. At this time, the slurry is not applied to the portion of the electrode body that is to be positioned on the outer peripheral portion, so that the aluminum foil is exposed, and the portion that is to be the positive electrode immediately below the outer peripheral aluminum foil layer is only one side. The slurry was applied. Thereafter, the slurry applied to the aluminum foil was dried by heating to produce a dry electrode plate having an active material layer formed on the aluminum foil. The dried electrode plate was compressed with a roller press and cut into a predetermined size to produce a positive electrode plate 11.

<Preparation of negative electrode plate>
Graphite as a negative electrode active material, styrene butadiene rubber as a binder, and carboxymethyl cellulose as a viscosity modifier were mixed at 95: 2: 3 (mass ratio), and the mixture was dispersed in water to prepare a slurry. This slurry was uniformly applied to both sides of a 10 μm thick copper foil by a doctor blade method. At this time, the slurry was not applied to the portion where the current collecting tab 19 is to be attached, and the copper foil was exposed. Then, the slurry apply | coated to copper foil was heat-dried, and the dry electrode plate in which the active material layer was formed on copper foil was produced. The dried electrode plate was compressed with a roller press and cut into a predetermined size, and then a current collecting tab 19 was attached to prepare the negative electrode plate 12.

<Production of electrode body>
The positive electrode plate 11, the negative electrode plate 12, and the separator 13 made of a polyethylene microporous film are wound into a cylindrical shape using a winder so that the positive electrode plate 11 and the negative electrode plate 12 are insulated by the separator 13, and then An electrode body was fabricated by molding so that the cross section was an oval shape. At this time, as shown in FIG. 2, one linear portion 101 having an elliptical cross section of the electrode body forms layers in order of the positive electrode, the separator, and the negative electrode from the outer periphery, and one curved portion 102 is formed from the outer periphery to the positive electrode and polypropylene. Insulating member 23 made of polypropylene tape coated with an adhesive on the sheet, a layer is formed in the order of the separator and the end of the negative electrode, and the other straight portion 103 is in order of the positive electrode, the separator, the end of the separator, the positive electrode, the separator, and the negative electrode The other curved portion 104 is wound so that the other curved portion 104 is structured in order of the positive electrode termination, the separator termination, the positive electrode, the separator, and the negative electrode from the outer periphery, and the positive electrode termination and the separator in the other curved portion The end was fixed with an end fixing tape 25 made of polypropylene tape, and the electrode body was fabricated by using a press machine so that the cross section was an oval. At this time, a U-shaped cut was made in the positive electrode aluminum foil on the outer periphery of the other straight portion, and the positive electrode current collecting tab 20 was produced in which the cut was raised on the sealing lid side, and a part on the sealing lid side of the electrode body A positive current collector tab protective tape 24 made of propylene tape was affixed to the tape. (The positive electrode current collecting tab 20 is not shown in FIG. 2) Note that the end of the separator in the other curved portion covers about 1/2 of the curved portion, and the end of the separator in the other straight portion is approximately the straight portion. It was arranged to cover 3/4.

<Preparation of electrolyte>
In a non-aqueous solvent in which ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate were mixed at a volume ratio of 20:50:30 (25 ° C., 1 atm), 0.9 mol / liter of lithium hexafluorophosphate as an electrolyte salt was added. 1 liter was dissolved.

<Battery assembly>
The sealing lid 16 having the negative electrode terminal 18 and the insulating spacer 22 is welded to the negative electrode current collecting tab 19 led out from the negative electrode plate of the electrode body, and the electrode body is accommodated in the outer container 15 to open and seal the outer container 15. The lid 16 was mated with the lid 16. The positive electrode current collecting tab 20 was sandwiched between the opening of the outer container 15 and the sealing lid 16 when they were mated. And the opening part of the exterior container 15 and the sealing part of the sealing lid 16 were laser-welded with the positive electrode current collection tab. Then, a predetermined amount of the electrolytic solution was injected from the liquid injection hole 21 and sealed with a liquid injection stopper (not shown). Thus, a square having a height of 43 mm, a width of 34 mm, a thickness of 4.3 mm and a design capacity of 750 mAh. A non-aqueous electrolyte secondary battery was produced.

Example 1
The nonaqueous electrolyte secondary battery of Example 1 was produced as described above.

(Example 2)
In the above embodiment, as shown in FIG. 3, the other straight line portion 103 is implemented in the same manner as in the above embodiment except that the positive electrode, the terminal end of the separator, the separator, the positive electrode, the separator, and the negative electrode are formed in this order from the outer periphery. The nonaqueous electrolyte secondary battery of Example 2 was produced. In addition, the end of the separator in the other curved portion was arranged so as to cover about 1/2 of the curved portion, and the end of the separator placed on the other straight portion was arranged so as to cover about 3/4 of the straight portion.

(Example 3)
In the above embodiment, as shown in FIG. 4, the other straight portion 103 forms layers in order of the positive electrode, the separator, the separator, the positive electrode, the separator, and the negative electrode from the outer periphery, and the other curved portion 104 extends from the outer periphery to the positive electrode termination, A nonaqueous electrolyte secondary battery of Example 3 was produced in the same manner as in the above embodiment except that the layers were formed in the order of the end of the separator, the end of the separator, the positive electrode, the separator, and the negative electrode. In addition, the terminal end of the separator in the other curved portion was arranged so as to cover about 1/2 of the curved portion.

(Comparative example)
In the above embodiment, as shown in FIG. 5, the other straight portion 103 is formed in the order of the positive electrode, the end of the separator, the end of the separator, the positive electrode, the separator, and the negative electrode from the outer periphery, and the other curved portion 104 is the outer periphery. A non-aqueous electrolyte secondary battery of a comparative example was fabricated in the same manner as in the above embodiment except that the layers were formed in the order of positive electrode termination, positive electrode, separator, and negative electrode. The end of the separator was disposed so as to cover about 3/4 of the other straight line portion.

<Discharge load characteristic test>
The prepared nonaqueous electrolyte secondary battery is charged at 25 ° C. with a constant current of 1 It (750 mA) until the battery voltage reaches 4.2 V, and further charged at 4.2 V with a constant voltage until 0.02 It (15 mA). Went. Then, constant current discharge was performed until it became 2.75V with a 1 It constant current at 25 degreeC, the discharge capacity at that time was measured, and it was set as the discharge capacity of the 1st cycle. Further, charging was performed at 25 ° C. with a constant current of 1 It until the battery voltage reached 4.2 V, and constant voltage charging was performed until it reached 0.02 It at 4.2 V. And constant current discharge was performed until it became 2.75V with the constant current of 3 It (2250mA) at 25 degreeC, the discharge capacity at that time was measured, and it was set as the discharge capacity of the 2nd cycle.
And the discharge load characteristic was computed like the following formula | equation.
Discharge load characteristics (%) = (discharge capacity at the second cycle) / (discharge capacity at the first cycle) × 100

<Charge / discharge cycle characteristics>
The produced non-aqueous electrolyte secondary battery was charged to 4.2 V with a constant current of 1 It at 25 ° C., and further subjected to constant voltage charging until it reached 0.02 It at 4.2 V. Next, constant current discharge was performed at 25 ° C. with a constant current of 1 It to 2.75 V, and the discharge capacity was measured. Moreover, the thickness of the battery was measured using a vernier caliper after the discharge was completed. This charge and discharge was defined as one cycle and repeated 300 cycles. The battery thickness was measured in the state where the discharge at the 300th cycle was completed. Then, as the charge / discharge cycle characteristics, the capacity retention rate after 300 cycles and the amount of expansion of the battery were calculated as in the following equations.
Residual capacity ratio (%) = (discharge capacity at the 300th cycle) / (discharge capacity at the first cycle) × 100
Expansion amount (%) = (Battery thickness after 300 cycles) / (Battery thickness at the first cycle) × 100

<Drop test>
Each of the nonaqueous electrolyte secondary batteries of Examples 1 to 3 and Comparative Example was charged to 4.2 V at a constant current of 1 It at 25 ° C., and further charged at a constant voltage until it became 1/50 It at 4.2 V. Went. Next, constant current discharge was performed at 25 ° C. to 2.75 V at a constant current of 1 It. The battery after discharge was measured for battery voltage and dropped vertically from a height of 2.0 m onto a concrete floor with the sealing lid facing downward. The battery voltage was measured each time the battery was dropped, and the battery was repeatedly dropped until the battery voltage decreased (that is, until a short circuit occurred inside the battery), and the number of times the battery voltage decreased was recorded.

  Table 1 shows the test results of the above Examples and Comparative Examples.

  When Examples 1 to 3 in which the end of the separator is an ellipse-shaped curved portion of the electrode body and a comparative example in which the end of the separator is not in the curved portion but only in the straight portion are compared, Examples 1 to 3 are more discharged. It can be seen that both the load characteristics and the charge / discharge cycle characteristics are excellent, and the amount of battery expansion after the charge / discharge cycles is small. Furthermore, in the drop test, it can be seen that in Examples 1 to 3, the battery voltage drops more times than in the comparative example, and a short circuit is less likely to occur inside the battery.

  This is considered as follows. That is, in the comparative example, the separator is terminated at a straight portion having an oval cross section of the electrode body, and a portion that forms a layer with the positive electrode, the positive electrode, the separator, and the negative electrode is generated from the outer periphery. When a pressing pressure at the time of molding the electrode body is applied to this portion, the pressure is also applied to the separator inside the electrode body, and the micropores of the separator are crushed. When the micropores of the separator are crushed, the flow of lithium ions performed through the micropores is hindered, resulting in resistance. For this reason, discharge load characteristics and charge / discharge cycle characteristics are deteriorated.

  On the other hand, in Examples 1 to 3, at least one separator in the lower layer of the positive electrode on the outer periphery of the electrode body is terminated with a curved portion having an elliptical cross section of the electrode body, and at least 1 is disposed on the lower layer of the outer peripheral positive electrode over the entire straight portion. A layer separator is present. This separator absorbs the pressure of the press applied at the time of electrode body shaping | molding, and relieve | moderates that the separator inside an electrode body receives a pressure. Therefore, the separator micropores are not easily crushed, and good battery characteristics are maintained.

  Further, in Examples 1 to 3 in the drop test, in the curved portion that is susceptible to deformation, since there is at least one separator in the lower layer of the outer peripheral positive electrode, the separator is deformed by dropping at the curved portion. Suppress and prevent short circuit. On the other hand, in the comparative example, since there is no separator in the lower layer of the outer peripheral positive electrode, it is considered that deformation due to dropping is not suppressed and a short circuit is likely to occur.

  In addition, in Examples 1 and 2 in which only one separator is terminated at the curved portion of the electrode body cross section ellipse in the lower layer of the positive electrode on the outer periphery of the electrode body, and the two layers of separator are curved with the electrode body cross section oval shape. Comparing with Example 3 terminated at the part, it can be seen that Example 3 has better discharge load characteristics and charge / discharge cycle characteristics, and the occurrence of short circuit is suppressed even in a drop test. This is because the two-layer separator of the ellipse linear section and the curved section of the electrode body can absorb the press pressure at the time of molding the electrode body more efficiently than the one-layer separator, and the deformation due to dropping is more effective. It is thought that it can be suppressed.

(extra content)
In the above embodiment, the end of the separator covers about 1/2 of the curved portion. However, if the end of the separator is disposed so as to cover 1/4 or more of the curved portion, the effect of the present invention is exhibited. Preferably, the end of the separator is disposed so as to cover the curved portion, more preferably 1/3 or more, more preferably 1/2 or more, and even more preferably 3/4 or more.

  According to the present invention, a non-aqueous electrolyte secondary battery having excellent discharge load characteristics, charge / discharge cycle characteristics, and drop reliability can be provided, and therefore, industrial applicability is great.

DESCRIPTION OF SYMBOLS 10 Nonaqueous electrolyte secondary battery 11 Positive electrode plate 12 Negative electrode plate 13 Separator 14 Electrode body 15 Exterior container 16 Sealing lid 20 Positive electrode current collection tab 23 Insulating member 24 Protective tape 25 Termination fixing tape 101 One linear part 102 One curved part 103 The other straight part 104 The other curved part

Claims (4)

A positive electrode in which an active material layer is formed on a metal foil, and a negative electrode are nonaqueous electrolyte secondary batteries in which an electrode body wound through a separator having micropores is housed in an outer container,
The electrode body has a cross-section that connects a pair of linear portions including one linear portion and the other linear portion, and one curved portion connecting one end of the one linear portion and one end of the other linear portion. The other end of the one immediately preceding portion and the other curved portion connecting the other end of the other straight portion, and the positive electrode, the negative electrode, and the separator are the one straight portion, the one straight portion, It is wound in the order of the curved portion, the other straight portion, and the other curved portion,
The one straight line portion is composed of a positive electrode, a separator, and a negative electrode in order from the outer periphery toward the winding center,
From the outer periphery toward the winding center, the one curved portion has a positive electrode, an insulating member that protects the electrode plate, a separator, and a terminal end of the negative electrode in order,
The other straight line portion has a positive electrode, a separator, a positive electrode, a separator, and a negative electrode in order from the outer periphery toward the winding center,
The other curved portion is characterized in that the end of the positive electrode, the end of the separator, the positive electrode, the separator, and the negative electrode are sequentially layered from the outer periphery toward the winding center.
Non-aqueous electrolyte secondary battery.   The said other straight part makes a layer in order of the positive electrode which consists of metal foil, a separator, the positive electrode which is metal foil on the outer peripheral side, a separator, and a negative electrode toward the winding center from the outer periphery. Non-aqueous electrolyte secondary battery.   3. The nonaqueous electrolyte secondary battery according to claim 1, wherein an end of the separator of the other curved portion is an end of the two-layer separator. 4. The non-aqueous electrolyte secondary battery according to claim 1, wherein a terminal end of the separator disposed in the other curved portion covers 1/2 or more of the curved portion. 5.