JP2017152284A - Bag-shaped separator and nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a box-shaped separator in which the joining strength between two separators is high and the separators are difficult to be peeled off even during manufacturing and use of a non-electrolyte secondary battery even when heat resistant layers are disposed on surfaces of the separators which face each other out of the surfaces of the separators.SOLUTION: In a bag-shaped separator 60 having two separators 50, each of the separators 50 includes a resin layer 52 containing polyolefin resin and a heat-resistant layer 54 containing inorganic particles, heat resistant layers 54 are arranged at least on the surfaces of two separators 50 on a side where the two separators 50 face each other, a plurality of joining portions 62 for joining the two separators 50 and a plurality of non-joining portions 64 adjacent to the joining portions 62 are provided at the outer peripheral portion of the bag-like separator 60, and the length L2 of the non-joint portions 64 is shorter than the length L1 of the joint portions 62.SELECTED DRAWING: Figure 3

Description

  The present disclosure relates to a bag-shaped separator and a non-aqueous electrolyte secondary battery.

  A lithium ion battery including a plurality of positive electrodes, negative electrodes, and separators each including a stacked electrode body in which positive electrodes and negative electrodes are alternately stacked via separators is widely known. In a lithium ion battery, the negative electrode is formed larger than the positive electrode in order to ensure smooth movement of lithium ions between the positive and negative electrodes.

  Patent Document 1 discloses a stacked secondary battery in which a positive electrode and a negative electrode are stacked opposite to each other with a separator between them. At least one of the positive electrode and the negative electrode is covered with a bag-shaped separator, and the separator is a positive electrode or a negative electrode. A multilayer secondary battery is described which is joined by a fusion joint provided intermittently around the periphery and has a peripheral fusion part on a part of the outer periphery of the separator.

Japanese Patent No. 5586044

  By the way, in order to prevent the resin constituting the separator from being melted by heat generated by charging / discharging or the like, a separator having a heat-resistant layer on the surface facing the positive electrode is manufactured. When producing a bag-shaped separator that covers the positive electrode using such a separator, the two separators are overlapped so that the heat-resistant layer is disposed on the surface of the separator that faces the two separators. Adapted. However, when two separators have heat-resistant layers arranged on the surfaces facing each other, when the two separators are fused from the direction perpendicular to the surface, the separators are joined together to sandwich the heat-resistant layer between them. The strength becomes insufficient, and the separator may be peeled off when the battery is manufactured or used.

  The bag-shaped separator according to the present disclosure is a bag-shaped separator including two separators, and each of the separators includes a resin layer including a polyolefin resin and a heat-resistant layer including inorganic particles. Two separators are disposed at least on the surfaces facing each other, a plurality of joints joining the two separators to the outer periphery of the bag-like separator, and a plurality adjacent to the joints The length of the non-joining portion is shorter than the length of the joining portion.

  A non-aqueous electrolyte secondary battery according to the present disclosure is a non-aqueous electrolyte secondary battery including a plurality of positive electrodes, negative electrodes, and a plurality of the above-mentioned bag-shaped separators, and the positive electrode is sandwiched between two separators. The positive electrode and the negative electrode held by the bag-like separator are alternately laminated.

  According to the bag-shaped separator according to the present disclosure, the bonding strength between the separators is high even when the heat-resistant layer is disposed on the surface of the separator on the side where the two separators face each other. It is possible to provide a bag-like separator that is difficult to peel off even during manufacture and use.

It is a perspective view which shows the external appearance of the nonaqueous electrolyte secondary battery which is an example of embodiment. It is a schematic diagram which shows the electrode body which is an example of embodiment. It is a front view of the bag-shaped parameter which is an example of embodiment. It is a side view of the bag-shaped parameter which is an example of embodiment. It is the sectional view on the AA line in FIG. It is a front view of the bag-shaped parameter which is another example of embodiment.

  As described above, when two separators are fused in a direction perpendicular to the surface in order to produce a bag-shaped separator that covers the positive electrode using a separator having a heat-resistant layer on the surface, the bonding strength between the separators is poor due to the heat-resistant layer. May be sufficient. For example, in the conventional bag-shaped separator non-aqueous electrolyte secondary battery described in Patent Document 1, two separators are fused from a direction perpendicular to the surface, and intermittent fusion-bonded portions having sufficient strength. However, since the fusion-bonded portion is provided at a portion where the surface of the separator contacts, there is a possibility that sufficient bonding strength cannot be obtained when the separator includes a release layer. Although the fusion of the outer periphery is also described, the fusion part only describes the use for preventing the misalignment between the electrodes and the separators. Furthermore, since the fused part is fused partly or entirely on the side surface, the non-aqueous electrolyte permeability is remarkably low, and separation such as peeling and cutting (hereinafter, referred to as “separation”) is performed even at one place of the fused part. If these are included and referred to as “peeling”), it may propagate from the peeled portion and peel off all the fused portions.

  The inventor has improved the bonding strength even when the bag-shaped separator according to the present disclosure has a heat-resistant layer disposed on the surface of the separator on the side where two separators face each other, Capability to produce a bag-like separator that is difficult to peel off during battery manufacture and use, good non-aqueous electrolyte permeability, and bonding strength between separators even if part of the joint is peeled off It was found that the decrease in the amount was suppressed.

  Hereinafter, an example of an embodiment of the present disclosure will be described in detail. Note that the bag-shaped separator and the nonaqueous electrolyte secondary battery according to the present disclosure are not limited to the embodiments described below. Since the drawings referred to in the description of the embodiments are schematically described, the dimensional ratios of the components drawn in the drawings should be determined in consideration of the following description. Further, in this specification, “substantially” means “substantially the same” as an example, and it is intended to include not only completely the same but also what is recognized as substantially the same.

[Nonaqueous electrolyte secondary battery]
FIG. 1 is a perspective view of a nonaqueous electrolyte secondary battery 10 which is an example of an embodiment. As illustrated in FIG. 1, the nonaqueous electrolyte secondary battery 10 includes an exterior body 11 and a power generation element accommodated in the exterior body 11. A suitable example of the nonaqueous electrolyte secondary battery 10 is a lithium ion battery. The power generation element includes a laminated electrode body 20 and a non-aqueous electrolyte (not shown). The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The nonaqueous electrolyte is not limited to a liquid electrolyte, and may be a solid electrolyte. The electrolyte salt is preferably a lithium salt.

  1 to 5, the z-axis is defined in the stacking direction of the electrode body 20, and the x-axis is defined in the direction along the side where the positive electrode terminal 15 and the negative electrode terminal 16 of the exterior body 11 are provided, The y axis is defined in a direction orthogonal to each of the x axis and the z axis.

  The exterior body 11 is composed of, for example, two laminated films. For each laminate film, it is preferable to use a film in which a resin layer is formed on both surfaces of a metal layer, and the resin layers in contact with each other are preferably made of a resin that can be thermocompression bonded. The metal layer is a thin film layer of aluminum, for example, and has a function of preventing permeation of moisture and the like. The exterior body that houses the power generation element is not limited to the exterior body 11 made of a laminate film, and may be, for example, a metal exterior can.

  The exterior body 11 includes a housing portion 13 that houses the power generation element, and a sealing portion 14 that is formed around the housing portion 13. One laminate film constituting the exterior body 11 is formed into a cup shape, and a flat, substantially rectangular parallelepiped housing portion 13 is formed on the film. The accommodating portion 13 is formed by drawing one laminate film so as to be convex on the opposite side to the other laminate film disposed opposite to the accommodation portion 13. The sealing portion 14 is formed by thermocompression bonding between the end portions of each laminate film, and seals the internal space of the housing portion 13 in which the power generation element is housed.

  The nonaqueous electrolyte secondary battery 10 includes a pair of electrode terminals (a positive electrode terminal 15 and a negative electrode terminal 16) drawn from the outer package 11. The positive electrode terminal 15 and the negative electrode terminal 16 are drawn from one end in the longitudinal direction of the exterior body 11. Each of the positive electrode terminal 15 and the negative electrode terminal 16 is a substantially flat plate-like body, and is bonded to each laminate film at the sealing portion 14, and passes through the sealing portion 14 and between each film to the outside of the exterior body 11. Pulled out.

[Electrode body]
In FIG. 2, the schematic diagram of the electrode body 20 which is an example of this embodiment is shown. The electrode body 20 includes a plurality of positive electrodes 30, negative electrodes 40, and bag-shaped separators 60, and each of the positive electrodes 30 is held inside the bag-shaped separator 60 so as to be sandwiched between two separators 50. As shown in FIG. 2, the stacked electrode body 20 has a configuration in which positive electrodes 30 and negative electrodes 40 held in a bag-shaped separator 60 are alternately stacked. In FIG. 2, the positive electrode 30 is indicated by a virtual line.

  In the electrode body 20, the number of the positive electrodes 30 and the negative electrodes 40 is not particularly limited, and can be, for example, about 10 or more and 70 or less. In order to ensure smooth movement of lithium ions between the electrodes, the negative electrode 40 is preferably formed larger than the positive electrode 30. Moreover, it is preferable that the area | region in which the positive mix layer of the positive electrode 30 was formed is arrange | positioned facing the area | region in which the negative mix layer of the negative electrode 40 was formed at least.

  The electrode body 20 includes a plurality of positive leads 32 connected to the positive electrodes 30 and a plurality of negative leads 42 connected to the negative electrodes 40. In the present embodiment, the positive electrode lead 32 is formed by projecting a part of the positive electrode current collector constituting the positive electrode 30, and the negative electrode lead 42 is formed by projecting a part of the negative electrode current collector constituting the negative electrode 40. Is formed. The positive electrode 30 and the positive electrode terminal 15 are electrically connected by overlapping a plurality of positive electrode leads 32 and welding them to the positive electrode terminal 15. Further, the plurality of negative electrode leads 42 are overlapped with each other and welded to the negative electrode terminal 16, whereby the negative electrode 40 and the negative electrode terminal 16 are electrically connected.

  The electrode body 20 is produced by laminating the bag-shaped separator 60 holding the positive electrode 30 and the negative electrode 40. Thereby, the stacked electrode body 20 in which the positive electrode 30 and the negative electrode 40 are arranged via the separator 50 is manufactured.

[Positive electrode]
The positive electrode 30 includes, for example, a positive electrode current collector and a positive electrode mixture layer formed on the current collector. As the positive electrode current collector, a metal foil that is stable in the potential range of the positive electrode such as aluminum, a film in which the metal is disposed on the surface layer, or the like can be used. The positive electrode mixture layer preferably contains a conductive material and a binder in addition to the positive electrode active material. The positive electrode mixture layer is preferably formed on both surfaces of the positive electrode current collector. As the positive electrode active material, for example, a lithium-containing composite oxide is used. Examples of suitable composite oxides include Ni-Co-Mn-based and Ni-Co-Al-based lithium-containing composite oxides.

  The positive electrode mixture layer formed on the positive electrode 30 has, for example, a rectangular shape. The positive electrode lead 32 has a shape protruding from one end of one side of the region where the positive electrode mixture layer is formed. The positive electrode lead 32 is a portion where the surface of the positive electrode current collector is exposed, and is thereby electrically connected to the positive electrode terminal 15. It is preferable to provide a protective layer having a higher electrical resistance than the insulating layer or the positive electrode core at the root portion where the positive electrode lead 32 and the region where the positive electrode mixture layer is formed.

  The thickness of the positive electrode 30 is not particularly limited, but is preferably 60 μm or more and 80 μm or less. For example, the positive electrode 30 is formed by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive material, a binder, etc. on a long positive electrode current collector, rolling the coating film, and collecting a positive electrode mixture layer. After being formed on both sides of the body, it can be manufactured by cutting it into the dimensions of each positive electrode 30 and positive electrode lead 32. The positive electrode mixture slurry is not applied to the portion that becomes the positive electrode lead 32 on the positive electrode current collector.

[Negative electrode]
The negative electrode 40 includes, for example, a negative electrode current collector and a negative electrode mixture layer formed on the current collector. As the negative electrode current collector, a metal foil that is stable in the potential range of a negative electrode such as copper, a film in which the metal is disposed on the surface layer, or the like can be used. The negative electrode mixture layer preferably contains a binder in addition to the negative electrode active material. The negative electrode mixture layer is preferably formed on both surfaces of the negative electrode current collector. The negative electrode active material is not particularly limited as long as it can reversibly occlude and release lithium ions, for example, carbon materials such as natural graphite and artificial graphite, metals such as Si and Sn, and metals that form an alloy with lithium, and Further, alloys of these metals and composite oxides can be used.

  The negative electrode 40 has the same shape as the positive electrode 30, but the dimensions of the negative electrode 40 are larger than the dimensions of the positive electrode 30 as described above. The negative electrode mixture layer formed on the negative electrode 40 has, for example, a rectangular shape. The negative electrode lead 42 is an end portion on one side of the region where the negative electrode mixture layer is formed, and has a shape protruding from the end portion on the side different from the positive electrode lead 32. The negative electrode lead 42 is a portion where the surface of the negative electrode current collector is exposed, and is thereby electrically connected to the negative electrode terminal 16.

  The thickness of the negative electrode 40 is not particularly limited, but is preferably 60 μm or more and 100 μm or less. The negative electrode 40 is formed by applying a negative electrode mixture slurry containing a negative electrode active material, a binder, etc. on a long negative electrode current collector, rolling the coating film, and forming negative electrode mixture layers on both sides of the current collector Then, it can be manufactured by cutting the negative electrode 40 and the negative electrode lead 42 into dimensions. Note that the negative electrode mixture slurry is not applied to the portion that becomes the negative electrode lead 42 on the negative electrode current collector.

[Bag separator]
3 and 4 are a front view and a side view (partial) showing a bag-like separator 60 holding the positive electrode 30 as an example of the present embodiment. 5 is a cross-sectional view taken along line AA in FIG. The bag-like separator 60 includes two separators 50 and has a shape formed by joining the two separators 50 by a plurality of joining portions 62, for example, a flat bag type or an envelope type. As described above, the bag-shaped separator 60 can be held inside the bag-shaped separator 60 such that the positive electrode 30 is sandwiched between the two separators 50. Thereby, compared with the case where the positive electrode 30 and the negative electrode 40 are simply laminated via the separator 50, the positive electrode 30, the negative electrode 40, or the separator 50 has a misalignment (in the xy plane in FIG. 2). Even if it moves, the short circuit between the positive electrode 30 and the negative electrode 40 can be prevented.

  The separator 50 includes a resin layer 52 containing a polyolefin resin and a heat-resistant layer 54 containing inorganic particles, and the heat-resistant layer 54 is at least a surface of the separator 50 on the side where the two separators 50 face each other. In other words, it is arranged on the surface that comes into contact with the positive electrode 30 in the bag-shaped separator 60. The separator 50 may include a heat resistant layer 54 on the surface opposite to the side where the two separators 50 face each other.

  The bag-shaped separator 60 has a plurality of joining portions 62 joining the two separators 50 and a plurality of non-joining portions 64 adjacent to the joining portion 62 on the outer peripheral portion. In this specification, the “outer peripheral portion” means the outer periphery of the separator surface, that is, the outermost region. For example, in the bag-shaped separator 60 shown in FIG. 3, the outer peripheral portion is a region composed of four sides along the x-axis and the y-axis in the rectangular separator 50 shown in FIG. 3. As shown in FIG. 3, an opening 66 is provided on the outer peripheral portion of the bag-like separator 60 in a region where the positive electrode lead 32 protrudes when holding the positive electrode 30.

  As shown in FIG. 4, each of the joining portions 62 extends in a direction along the outer periphery of the bag-like separator 60 (for example, the y-axis direction for the joining portion 62 shown in FIG. 4) with a length L <b> 1. . The plurality of joining portions 62 are provided at intervals L2 along the outer periphery of the bag-like separator 60.

  The non-joining part 64 is an area adjacent to the joining part 62 and thus not formed with the joining part 62, and has a length L2 in the direction along the outer periphery of the bag-like separator 60 (y-axis direction in FIG. 4). Have In the bag-like separator 60 of the present embodiment, the length L2 of the non-joining portion 64 is shorter than the length L1 of the joining portion 62.

  As shown in FIG. 5, the bag-like separator 60 of the present embodiment has a structure in which two separators 50 are joined beyond the heat-resistant layer 54 at the outer peripheral portion by providing a plurality of joining portions 62 at the outer peripheral portion. It has. Therefore, it is possible to provide the joint portion 62 that joins the two separators 50 without interposing the heat-resistant layer 54 therebetween, and it is possible to avoid a decrease in joint strength due to the heat-resistant layer 54.

  Moreover, since the bag-like separator 60 of the present embodiment is provided with a plurality of non-joining portions 64 having a length L2 shorter than the length L1 of the joining portion 62 adjacent to the joining portion 62, the nonaqueous electrolyte permeates. In addition, the positive electrode active material desorbed from the positive electrode 30 can be prevented from moving to the vicinity of the negative electrode 40 and inducing a short circuit.

  Furthermore, the bag-like separator 60 of the present embodiment includes a plurality of joint portions 62 and a plurality of non-joint portions 64, so that even if a part of the joint portion 62 is peeled off for some reason, the joint portion Since the non-joining portion 64 is adjacent to 62, peeling does not propagate to the other joining portion 62 beyond the non-joining portion 64 on both sides. Therefore, even if a part of the joining part 62 is peeled off, most of the joining parts 62 that join the two separators 50 maintain the joining strength, so that the joining strength between the two separators does not decrease. Or at least minimally.

  Hereinafter, an example of the manufacturing method of the bag-like separator 60 according to the present embodiment will be described. The heat-resistant layer 54 is formed on at least one surface of the belt-shaped resin film to be the resin layer 52 by the above-described method or the like to manufacture the belt-shaped separator 50. The manufactured two strip-shaped separators 50 are arranged so that the heat-resistant layers 54 face each other, and the two strip-shaped separators 50 are overlapped. The two overlapped strip-shaped separators 50 are cut according to a predetermined outer dimension. The bag-like separator 60 is formed by forming the joint 62 using the joining means on the outer periphery of the two separated separators 50 while cutting the two strip-shaped separators 50 or after cutting. Can be manufactured.

  As a joining means for forming the joining portion 62, for example, a heating fusion means for applying a heated fusion means to the outer peripheral portion of the separator 50, or an ultrasonic fusion means for fusing the resin layer 52 of the separator 50 by ultrasonic waves. And an adhesive applying means for applying an adhesive to the outer peripheral portion of the separator 50.

  In the conventional method of manufacturing a bag-shaped separator by thermally cutting two strip-shaped separators 50, the resin is melted by applying the heat-fusing means from the direction perpendicular to the surface (the z-axis direction in FIG. 3). While cutting. Therefore, the conventional method by thermal cutting cannot be applied to the manufacture of the bag-shaped separator 60 of the present embodiment having the heat-resistant layer 54 on the opposing surfaces of the two separators 50. For example, when manufacturing the bag-shaped separator 60 which concerns on this embodiment using the strip | belt-shaped separator 50 whose x-axis direction shown in FIG. 3 is a longitudinal direction, after cutting the said 2 strip | belt-shaped separator 50, Otherwise, the joint 62 cannot be formed on a surface (hereinafter also referred to as “side surface”) extending along the y-axis in the outer peripheral portion. From these viewpoints, in the manufacturing method of the bag-like separator 60 according to the present embodiment, the joining means is provided in a direction parallel to the surface of the separator 50 and perpendicular to the outer periphery (for example, the x direction in FIG. 4). Preferably, a plurality of joints 62 are formed by application.

  The bag-like separator 60 according to the present embodiment has two sheets by fusing the resin layer 52 of the separator 50 to form the joint portion 62 using the heat fusion means or the ultrasonic fusion means. It is preferable to include a plurality of joint portions 62 that are joined to each of the resin layers 52 in the separator 50 and are made of a polyolefin resin contained in the resin layer 52. Since such a joining portion 62 has the same composition as each of the resin layers 52 and has an integral inseparable structure without joining boundaries with the respective resin layers 52, the joining strength is further improved and is difficult to peel off. A bag-like separator 60 is obtained. In addition, since the lengths L1 and L2 and the arrangement of each of the plurality of joint portions 62 and the plurality of non-joint portions 64 can be easily adjusted, the joint portion 62 may be formed by the heating and melting means. preferable.

  When manufacturing the bag-shaped separator 60, before and after the step of stacking the two strip-shaped separators 50 before forming the joint portion 62, the separately manufactured positive electrode 30 is interposed between the heat-resistant layers 54 facing each other. It is preferable to arrange in advance. This is because the second joining step for joining the openings formed for putting the positive electrode 30 in the bag-like separator 60 can be omitted, and all the joining parts 62 can be formed in one joining step.

  The length L1 of the joint portion 62 and the length L2 of the non-joint portion 64 are not particularly limited as long as the length L2 is shorter than the length L1, but for example, the length of the plurality of joint portions 62 L1 is preferably 2 mm or more and 15 mm or less, and the length L2 of the plurality of non-joining portions 64 is preferably 0.1 mm or more and 3 mm or less. When the length L1 of the joined portion 62 and the length L2 of the non-joined portion 64 are in the above ranges, the detached positive electrode active material is moved to the vicinity of the negative electrode 40 while maintaining the electrolyte permeability. Further suppression can be achieved.

  The fact that the non-joining portions 64 are arranged at substantially equal intervals along the outer periphery of the bag-like separator 60, that is, that the lengths L1 of the joining portions 62 are substantially the same, is caused by thermal contraction of the separator 50. It is preferable from the viewpoint of suppressing. The non-joining portions 64 are arranged at substantially equal intervals, for example, the interval (length L1) between adjacent non-joining portions 64 is included in the range of 90% to 110% with respect to the average. There are cases.

  The structure of the separator 50 will be described. The polyolefin resin contained in the resin layer 52 is not particularly limited, but preferably has a glass transition temperature of 100 ° C. or higher from the viewpoint of thermoplasticity suitable for forming the joint portion 62 by heat fusion, For example, polyethylene, polypropylene and the like are preferable. The resin layer 52 may include a material other than the polyolefin resin, and may include, for example, cellulose. The resin layer 52 preferably has a polyolefin resin as a main component (for example, 20% by mass or more based on the total amount of the resin layer 52), and is particularly preferably composed of a polyolefin resin.

  As the resin layer 52, a porous sheet having ion permeability and insulating properties is used. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. The resin layer 52 may be a laminate, for example, a laminate including a polyethylene layer and a polypropylene layer.

  The inorganic particles contained in the heat-resistant layer 54 are, for example, particles composed of inorganic compounds such as oxides, carbides, nitrides, borides, and phosphate compounds containing metal elements such as Ti, Al, Si, and Mg. Is mentioned. The heat-resistant layer 54 may be substantially composed of inorganic particles. The heat-resistant layer 54 can be formed by, for example, applying a slurry containing inorganic compound particles to the surface of the resin layer 52.

  Although the thickness of the separator 50 is not specifically limited, Preferably it is 10 micrometers or more and 30 micrometers or less, More preferably, they are 10 micrometers or more and 18 micrometers or less. The thickness of the resin layer 52 and the thickness of the heat-resistant layer 54 are not particularly limited. For example, the resin layer 52 is preferably 8 μm to 16 μm and the heat-resistant layer 54 is preferably 2 μm to 6 μm.

  The outer dimensions of the bag-shaped separator 60 (the lengths of the four sides in the x-axis direction and the y-axis direction in FIG. 3) are preferably the same as the outer dimensions of the negative electrode 40. This is because, when the electrode body 20 is manufactured, when the plurality of positive electrodes 30 and the plurality of negative electrodes 40 are stacked, it is easy to arrange them in a predetermined position on the xy plane (so-called positioning).

  As described above, the joining portion 62 is preferably formed by fusing the resin layer 52 of the separator 50. In this case, the joining portion 62 has the same composition as the resin layer 52 and is composed of a polyolefin resin such as polyethylene or polypropylene. Is done.

  The joint portion 62 may be formed by bonding the outer peripheral portions of the two separators 50 using an adhesive. As an adhesive in that case, for example, an adhesive mainly composed of a resin can be used. As the resin used for the adhesive, from the viewpoint of adhesiveness to the resin layer 52, bondability with the resin layer 52 when solidified, and excellent electrolyte resistance, olefinic resins such as polyethylene and polypropylene, and Fluorine resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF) are preferred.

  Another example of this embodiment will be described with reference to FIG. As shown in FIG. 6, the bag-like separator 60 may have uneven portions formed along the outer periphery on the side surface (two sides extending in the y-axis direction in FIG. 6) of the bag-like separator 60. Good. The bag-like separator 60 according to the present embodiment can suppress the displacement of the positive electrode 30 (movement in the xy plane in FIG. 2) to some extent by providing a plurality of joining portions 62 on the outer peripheral portion, but the bag having an uneven portion on the side surface. Since the function which suppresses the shift | offset | difference of the positive electrode 30 can be improved more, the shape separator 60 is preferable. Moreover, when the bag-shaped separator 60 has a concavo-convex portion on the side surface, the portion close to the positive electrode 30 that becomes the concave portion of the concavo-convex portion is not bonded from the viewpoint of preventing peeling and the function of suppressing the displacement of the positive electrode 30. The portion 64 is preferable.

  The bag-shaped separator 60 having the uneven portions on the side surface has, for example, a cutting means for cutting the two strip-shaped separators 50 and a joining means for forming a plurality of joining portions 62 in a desired uneven portion shape. It can be manufactured in the same manner as the manufacturing method of the bag-like separator 60 shown in FIG. 3 except that the shape is appropriately changed to the combined shape.

  DESCRIPTION OF SYMBOLS 10 Nonaqueous electrolyte secondary battery, 11 exterior body, 13 accommodating part, 14 sealing part, 15 positive electrode terminal, 16 negative electrode terminal, 20 electrode body, 30 positive electrode, 32 positive electrode lead, 40 negative electrode, 42 negative electrode lead, 50 separator, 52 resin layer, 54 heat-resistant layer, 60 bag-shaped separator, 62 bonded portion, 64 non-bonded portion, 66 opening.

Claims (7)

A bag-shaped separator comprising two separators,
Each of the separators includes a resin layer containing a polyolefin resin, and a heat-resistant layer containing inorganic particles,
The heat-resistant layer is disposed at least on the surface of the separator on the side where the two separators face each other,
A plurality of joints joining two separators to the outer periphery of the bag-shaped separator, and a plurality of non-joining parts adjacent to the joints;
The length of the said non-joining part is a bag-shaped separator shorter than the length of the said joining part.   The bag-like separator according to claim 1, wherein the joining portion is joined to each of the resin layers in the two separators and is configured by the polyolefin resin contained in the resin layer.   The length of the said junction part is 2 mm or more and 15 mm or less, and the length of the said non-joining part is 0.1 mm or more and 3 mm or less, The bag shape as described in any one of Claims 1-3. Separator.   The said bag-shaped separator is a bag-shaped separator as described in any one of Claims 1-3 which has the uneven | corrugated | grooved part currently formed along the outer periphery in the side surface of the said bag-shaped separator.   The bag-shaped separator according to claim 4, wherein the concave portion of the concave and convex portion is the non-joined portion.   The bag-like separator according to any one of claims 1 to 5, wherein the non-joining portions are arranged at substantially equal intervals along an outer periphery of the bag-like separator. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a plurality of bag-shaped separators according to any one of claims 1 to 6,
The positive electrode is held by the bag-like separator so as to be sandwiched between the two separators,
A nonaqueous electrolyte secondary battery in which the positive electrode and the negative electrode held by the bag-like separator are alternately laminated.