CN220628167U

CN220628167U - Secondary battery and electronic device

Info

Publication number: CN220628167U
Application number: CN202322294374.6U
Authority: CN
Inventors: 车佩佩; 柳金华
Original assignee: Vision Power Technology Hubei Co ltd; Yuanjing Power Technology Ordos Co ltd; Envision Power Technology Jiangsu Co Ltd; Envision Ruitai Power Technology Shanghai Co Ltd
Current assignee: Vision Power Technology Hubei Co ltd; Yuanjing Power Technology Ordos Co ltd; Envision Power Technology Jiangsu Co Ltd; Envision Ruitai Power Technology Shanghai Co Ltd
Priority date: 2023-08-24
Filing date: 2023-08-24
Publication date: 2024-03-19
Anticipated expiration: 2033-08-24

Abstract

The present utility model provides a secondary battery and an electronic device, the secondary battery including: the bare cell comprises a first pole piece, a second pole piece and a diaphragm, wherein the diaphragm is arranged between the first pole piece and the second pole piece; the bare cell comprises a straight region, a first corner region and a second corner region, wherein the first corner region and the second corner region are arranged at two ends of the straight region; and an insulating tape disposed outside the bare cell, the insulating tape at least partially covering the straight region, the first corner region, and the second corner region. The secondary battery and the electronic equipment provided by the utility model can improve full charge wrinkling of the outer ring of the negative electrode, reduce the phenomenon of lithium precipitation and improve the performance of the secondary battery.

Description

Secondary battery and electronic device

Technical Field

The utility model relates to the technical field of secondary batteries, in particular to a secondary battery and electronic equipment.

Background

Along with the development of new energy automobiles, secondary batteries mainly comprising lithium ion batteries are rapidly developed, the lithium ion batteries comprise square shell batteries, soft package batteries and cylindrical batteries, the lithium ion batteries comprise bare cells and structural members for sealing the bare cells, and the lithium ion batteries can be divided into winding bare cells and lamination bare cells according to different molding modes of the bare cells. Among them, the winding speed is high, and thus, the winding is widely used as a molding method of a bare cell. In the winding process, after the positive and negative pole pieces and the diaphragm are wound, the diaphragm and the positive and negative poles are required to be fixed at the tail-end part of the diaphragm, so that the loose bare cell is prevented.

However, the last circle of positive and negative pole pieces and the diaphragm of the wound bare cell are freely wound through the winding machine in a Zhang Lishuai tail mode, when the winding machine is fixed, the winding force of the outer ring corner of the bare cell is small, the problems that the clearance between the diaphragm of the outer ring corner and the pole pieces is overlarge or the negative pole of the outer ring of the bare cell is full-charged and wrinkled and the like are caused, lithium precipitation is easy to cause, and therefore the cycle performance is affected.

Disclosure of Invention

The secondary battery and the electronic equipment provided by the utility model can improve the insulativity of the secondary battery, improve the full charge wrinkling of the outer ring of the negative electrode, reduce the phenomenon of lithium precipitation and improve the performance of the secondary battery.

In order to solve the above technical problems, the present utility model provides a secondary battery, at least comprising:

the bare cell comprises a first pole piece, a second pole piece and a diaphragm, wherein the diaphragm is arranged between the first pole piece and the second pole piece; the bare cell comprises a straight region, a first corner region and a second corner region, wherein the first corner region and the second corner region are arranged at two ends of the straight region; and

and the insulating tape is arranged on the outer side of the bare cell and at least partially covers the straight area, the first corner area and the second corner area.

In an embodiment of the utility model, the insulating tape covers the straight region and/or the insulating tape covers the first corner region.

In an embodiment of the utility model, the ending region of the first pole piece and/or the second pole piece is within the second corner region; and/or the number of the groups of groups,

the insulating tape is integrally arranged.

In one embodiment of the present utility model, the flat region includes a first flat region and a second flat region disposed opposite to each other across the bare cell.

In one embodiment of the utility model, the insulating tape covers the straight region, the first corner region and at least part of the second corner region.

In one embodiment of the present utility model, the portion of the second corner region covered by the insulating tape includes a first arc-shaped region and a second arc-shaped region;

the first arc-shaped region is an arc-shaped region formed by the second corner region covered by the insulating tape and contacted with the end point of the first straight region, and the second arc-shaped region is an arc-shaped region formed by the second corner region covered by the insulating tape and contacted with the end point of the second straight region.

In an embodiment of the present utility model, the central angle of the area where the first arc-shaped area is located is 3 ° to 80 °, and/or the central angle of the area where the second arc-shaped area is located is 3 ° to 80 °.

In an embodiment of the utility model, the secondary battery further includes a housing or an aluminum-plastic film, the housing is an aluminum housing, the housing and the aluminum-plastic film are provided with a containing cavity, and the bare cell is arranged in the containing cavity.

In an embodiment of the present utility model, the insulating tape is one of high temperature resistant adhesive paper, polyacrylate pressure sensitive adhesive paper, organic silicon pressure sensitive adhesive paper, rubber pressure sensitive adhesive paper or polyvinylidene fluoride adhesive tape.

The application also provides electronic equipment comprising a plurality of secondary batteries.

In summary, the utility model provides a secondary battery and an electronic device, which can reduce the gap between the diaphragm of the outer ring and the pole piece, improve the problem of full charge wrinkling of the outer ring of the negative electrode, and improve the performance of the secondary battery. The insulating tape wrapped in the annular way can improve the insulativity of the bare cell and improve the safety performance of the cell. The insulating tape covers the flat area, so that the flatness of the flat area of the bare cell can be ensured, and meanwhile, the gap between the first pole piece and the second pole piece in the corner area of the outermost coil is reduced, and lithium precipitation is prevented, so that the cycle performance of the secondary battery is improved. The rubberizing of first arc district and second arc district can reduce later stage turning clearance, prevents to separate out lithium, improves the security performance of secondary cell. The insulating tape reserves the breach in the second corner district of first pole piece and second pole piece, can be used for the extension of secondary cell at width direction, and prevents at the secondary cell cycle later stage, because of the insulating tape disconnection that the electricity core inflation leads to, can prevent that the stress from concentrating in the corner district, further prevent that the lithium phenomenon from taking place, improve secondary cell security performance.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic perspective view of a secondary battery according to an embodiment.

Fig. 2 is a schematic view of a secondary battery in an embodiment.

Fig. 3 is a schematic illustration of the ending regions of the first pole piece and the second pole piece in different embodiments.

Fig. 4 is a cross-sectional view of a bare cell in an embodiment.

Fig. 5 is a cross-sectional view of a bare cell in another embodiment.

Marking:

10. bare cell: 101. a first pole piece; 102. a second pole piece; 103. a diaphragm; 104. an insulating tape; 20. a housing; 21. a first pole; 22. a second post; 23. an explosion-proof valve.

Detailed Description

Other advantages and effects of the present utility model will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present utility model with reference to specific examples. The utility model may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present utility model.

It should be understood that the present utility model may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the utility model to those skilled in the art.

In the present utility model, it should be noted that, as terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., appear, the indicated orientation or positional relationship is based on that shown in the drawings, only for convenience of description and simplification of the description, and does not indicate or imply that the indicated apparatus or element must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, as used herein, are used for descriptive and distinguishing purposes only and are not to be construed as indicating or implying a relative importance.

The present utility model provides an electronic device comprising at least one secondary battery for providing electrical energy. The electronic device may be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. In an embodiment of the utility model, the vehicle may be a fuel oil vehicle, a fuel gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid electric vehicle or an extended range vehicle. Spacecraft include airplanes, rockets, space planes, spacecraft, and the like, and electric toys include fixed or mobile electric toys, including, for example, game consoles, electric car toys, electric ship toys, electric airplane toys, and the like. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railroad power tools, including, for example, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete shakers, and electric planers, among others. The embodiment of the application does not limit the electric device in particular.

Referring to fig. 1 to 4, in an embodiment of the present utility model, a secondary battery is provided including a case 20, a post and an explosion-proof valve 23 disposed at one end of the case 20, and a bare cell 10 disposed in the case, the bare cell 10 being electrically connected to the post on the case 20. The bare cell 10 comprises a first pole piece 101, a second pole piece 102 and a diaphragm 103, wherein the diaphragm 103 is arranged between the first pole piece 101 and the second pole piece 102, and the three are wound to form the bare cell 10. The bare cell 10 includes a flat region a, a first corner region B and a second corner region, the first corner region B and the second corner region are disposed at both ends of the flat region a, the insulating tape 104 is disposed outside the bare cell 10, and the insulating tape 104 at least partially covers the flat region a, the first corner region B and the second corner region. In the description of this application, covering means that the insulating tape is entirely covered over the described area, and partially covered is until the insulating tape is incompletely covered over the described area where there is a bare area where no insulating tape is provided.

Referring to fig. 1 to 2, in an embodiment of the present utility model, the shape of the housing 20 is, for example, a circle, a square, a rectangle with rounded corners, or the like, and is, for example, matched with the shape of the bare cell 10. Wherein, one end of the housing 20 is sealed, and the other end is provided with an opening, and the housing 20 forms a receiving cavity to receive the bare cell 10. In the present utility model, the case 20 is a rigid case such as an aluminum case or a steel case. In another embodiment of the present utility model, in the secondary battery, for example, an aluminum plastic film is used instead of the case 20, the aluminum plastic film is formed with a receiving cavity, and the bare cell 20 is disposed in the receiving cavity.

Referring to fig. 1 to 2, in an embodiment of the present utility model, the pole includes a first pole 21 and a second pole 22, and the first pole 21, the second pole 22 and the explosion-proof valve 23 are disposed on the same side of the housing 20. Specifically, after the bare cell is placed in the casing 20, an electrolyte is injected, the casing is sealed, and the first pole 21, the second pole 22 and the explosion-proof valve 23 are disposed at the sealed end. The polarities of the first pole 21 and the second pole 22 are opposite, the first pole 21 and the second pole 22 are respectively positive pole or negative pole, and the utility model is not limited to the specific corresponding polarity types of the first pole 21 and the second pole 22. The first pole 21 is electrically connected with the pole lug with the same polarity on the bare cell 10, and the second pole 22 is electrically connected with the pole lug with the same polarity on the bare cell 10 so as to lead out the voltage of the secondary battery. By providing the first and second poles 21 and 22 on the same side of the case 20, the space utilization within the case 10 can be improved while simplifying the secondary batteries, facilitating connection of a plurality of secondary batteries in the battery module.

Referring to fig. 1 to 2, in an embodiment of the present utility model, the explosion-proof valve 23 is disposed between the first pole 21 and the second pole 22, and is disposed at a middle position of the first pole 21 and the second pole 22, and has a predetermined distance from the first pole 21 and the second pole 22, i.e. the explosion-proof valve is not in contact with the first pole 21 and the second pole 22. The explosion-proof valve 23 can open the ventilation function when the secondary battery works normally, so that the air flow inside and outside the secondary battery can circulate, the particles can not circulate, when the thermal runaway of the secondary battery occurs, the pressure difference inside and outside the secondary battery reaches the explosion-proof preset value, the explosion-proof valve is opened, and the gas and the solid can be discharged from the inside of the secondary battery to the outside of the secondary battery through the explosion-proof valve, so that the safety performance of the secondary battery is improved.

Referring to fig. 1 to 3, in an embodiment of the present utility model, a first electrode 101, a second electrode 102 and a separator 103 in a bare cell 10 are wound in the same direction. Wherein the diaphragm 103 is located between the first pole piece 101 and the second pole piece 102, isolating the wound first pole piece 101 from the second pole piece 102. The polarities of the first pole piece 101 and the second pole piece 102 are opposite, the first pole piece 101 and the second pole piece 102 are respectively positive pole pieces or negative pole pieces, and the utility model is not limited to the types of pole pieces specifically corresponding to the first pole piece 101 and the second pole piece 102. In the present embodiment, at least one side of the first and second electrode sheets 101 and 102 is coated with an active material layer, and for example, both sides are coated with an active material layer to improve the capacity performance of the secondary battery.

Referring to fig. 3 to 4, in an embodiment of the present utility model, in a bare cell 10, a separator 103, a first electrode sheet 101, a separator 103, and a second electrode sheet 102 are sequentially stacked in this order, and then wound around the same direction, thereby obtaining the bare cell 10. Wherein, the lengths of the first pole piece 101 and the second pole piece 102 are equal, and the first pole piece 101 and the second pole piece 102 are staggered and laminated at a winding starting position. The length of the diaphragm 103 is greater than the lengths of the first pole piece 101 and the second pole piece 102, and in the winding start position, the length of the diaphragm 103 is greater than the lengths of the first pole piece 101 and the second pole piece 102, and in the winding end position, the length of the diaphragm 103 is greater than the lengths of the first pole piece 101 and the second pole piece 102, so that the first pole piece 101 and the second pole piece 102 are ensured not to contact each other, and short circuits are avoided. In the present utility model, the specific lengths of the first electrode sheet 101, the second electrode sheet 102 and the separator 103 are not limited, and are determined according to the size of the wound bare cell 10.

Referring to fig. 1 to 4, in an embodiment of the utility model, a positive electrode tab or a negative electrode tab (not shown) is disposed on each of the first electrode tab 101 and the second electrode tab 102. In an embodiment of the present utility model, when the first pole piece 101 is, for example, a positive pole piece, a plurality of positive pole tabs are disposed on the first pole piece 101 at intervals, and after the first pole piece 101 is wound, the positive pole tabs are located at the same position so as to be connected with the first pole piece 21 or the second pole piece 22 with the same polarity, and the corresponding second pole piece 102 is a negative pole piece correspondingly, and is provided with a negative pole tab.

Referring to fig. 3 to 4, in an embodiment of the present utility model, the bare cell 10 is, for example, square or rounded rectangle, and is, for example, rounded rectangle, and the ending sections of the first pole piece 101 and the second pole piece 102 are, for example, rounded ends. Wherein, two flat regions of the bare cell 10 with large surfaces opposite to each other are defined as a flat region A, and connection regions at two ends of the flat region A are defined as corner regions. The flat area A comprises a first flat area A1 and a second flat area A2, the first flat area A1 and the second flat area A2 are oppositely arranged, the corner area comprises a first corner area B and a second corner area, and the first corner area B and the second corner area are respectively positioned at two ends of the flat area A so as to connect the first flat area A1 and the second flat area A2. In the winding process, the ending region of the first pole piece 101 and/or the second pole piece 102 is, for example, in the second corner region, that is, by arranging the ending end of the pole piece in the second corner region, the extrusion of the pole piece can be reduced relative to the ending region to the flat region, and the increase of the distance between the pole pieces can be prevented, so that the lithium precipitation phenomenon is reduced.

Referring to fig. 3 to 5, in an embodiment of the present utility model, the insulating tape 104 covers at least the flat region a, the first corner region B and the second corner region. In one embodiment of the present utility model, the insulating tape 104 covers, for example, the first straight region A1, a portion of the first corner region B, and a portion of the second corner region. In another embodiment of the present utility model, the insulating tape 104 covers, for example, the first straight region A1, the first corner region B, and a portion of the second corner region. In another embodiment of the present utility model, the insulating tape 104 covers, for example, the first straight region A1, the first corner region B, a portion of the second straight region A2, and a portion of the second corner region. In another embodiment of the present utility model, the insulating tape 104 covers, for example, the first straight region A1, the first corner region B, the second straight region A2, and a portion of the second corner region. That is, in the present utility model, the insulating tape 104 covers at least one side flat region, and part of corner regions at both ends of the flat region.

Referring to fig. 3 to 5, in an embodiment of the present utility model, an insulating tape 104 is used to cover, for example, the first flat area A1, the first corner area B, the second flat area A2, and a part of the second corner area. Wherein a portion of the second corner region covered by the insulating tape 104 is connected to the first straight region A1, and an arc region formed by the second corner region covered by the insulating tape 104 in contact with an end point of the first straight region A1 is defined as a first arc region C. A portion of the second corner region covered by the insulating tape 104 is connected to the second straight region A2, and an arc region formed by the second corner region covered by the insulating tape 104 in contact with the end point of the second straight region A2 is defined as a second arc region D, and the first arc region C and the second arc region D are disposed at a spacing. In an embodiment of the present utility model, the central angle of the area where the first arc-shaped area C is located is, for example, 3 ° -80 °, and the central angle of the area where the second arc-shaped area D is located is, for example, 3 ° -80 °. The central angles of the areas where the first arc-shaped area C and the second arc-shaped area D are located can be equal or unequal.

Referring to fig. 3 to fig. 4, in the process of covering the bare cell 10 of the insulating tape 104, the insulating tape 104 is sequentially coated on the second arc-shaped region D, the second straight region A2, the first corner region B, the first straight region A1 and the first arc-shaped region C, i.e. the first arc-shaped region C is the ending region of the insulating tape 104, for example, from the second arc-shaped region D. In other embodiments, the insulating tape 104 may also cover the first arc-shaped region C, the first flat region A1, the first corner region B, the second flat region A2 and the second arc-shaped region D sequentially from the first arc-shaped region C as a starting and ending region. I.e., the starting area and direction of the insulating tape 104 is not limited after the winding of the pole piece is completed.

Referring to fig. 3 to 5, in an embodiment of the present utility model, an insulating tape 104 is wrapped on the outer side of the bare cell 10 in a ring shape and covers at least a flat area on one side and a part of corner areas on both sides, so that on one hand, the insulation of the bare cell can be improved, and on the other hand, the safety performance of the cell can be improved, and on the other hand, the first pole piece 101, the second pole piece 102 and the diaphragm 103 of the battery can be effectively fixed. Meanwhile, the flatness of the flat area A of the bare cell 10 is ensured, and meanwhile, the gap between the first pole piece 101 and the second pole piece 102 in the corner area of the winding outermost ring is reduced, namely, the gap between the first pole piece 101 and the second pole piece 102 in the first corner area B and the second corner area is reduced, and lithium precipitation is prevented, so that the cycle performance of the secondary battery is improved. And after the secondary battery circulates, the corners are extruded, the gaps of the first arc-shaped area C and the second arc-shaped area D are increased, the insulating strips on the first arc-shaped area C and the second arc-shaped area D can reduce the corner gaps at the later stage, lithium precipitation is prevented, and the safety performance of the secondary battery is improved.

Referring to fig. 3 to 5, in an embodiment of the present utility model, an insulating tape 104 partially covers the outside of the bare cell 10, for example, in the ending region of the first pole piece 101 and the second pole piece 102, a reserved gap exists in the insulating tape 104, for example, in the second corner region, the first arc region C and the second arc region D covered by the insulating tape 104 are not adjacent, i.e., no insulating tape 104 is disposed in the region between the first arc region C and the second arc region D, so as to reduce the gap between the first pole piece 101 and the second pole piece 102 at the outermost corner, and prevent lithium precipitation. Meanwhile, after the insulating tape 104 is arranged, when the hot pressing process is performed again, the width of the bare cell can be increased, a reserved gap of the insulating tape 104 is used for extending the secondary battery in the width direction, the bare cell is expanded in the later cycle, the ductility of the insulating tape 104 is poor, the reserved gap can prevent stress from being concentrated at the corner, and the phenomenon of lithium precipitation is further prevented. In this embodiment, the length of the insulating tape 104 can be accurately controlled by the winding machine to ensure that the insulating tape 104 is wrapped in a ring shape and a gap is reserved.

Referring to fig. 2 to 5, in an embodiment of the present utility model, the insulating tapes 104 are integrally disposed, and the thickness of the insulating tapes 104 is, for example, 10 μm-50 μm, and is, for example, 16 μm, 22 μm, or 30 μm, and the thickness of the insulating tapes 104 in different regions is equal. The insulating tape 104 is, for example, one of high temperature resistant adhesive paper, polyacrylate pressure sensitive adhesive paper, silicone pressure sensitive adhesive paper, rubber pressure sensitive adhesive paper, polyvinylidene fluoride adhesive tape, or the like. Through the annular wrapped insulating tape 104, the distance between the bare cell 10 and the shell 20 can be reduced, the group margin of the secondary battery is improved, namely the ratio of available space of the shell is improved, the full charge wrinkling of the outer ring cathode of the bare cell caused by low group margin is prevented, the lithium precipitation risk caused by the wrinkling part in the circulation process is reduced, and the circulation performance of the secondary battery is improved.

The secondary battery is applied to the electronic equipment, and the electronic equipment comprises all the technical schemes of the secondary battery, so that the secondary battery has at least all the beneficial effects brought by the technical schemes of the related secondary battery, and the detailed description is omitted.

In summary, the utility model provides a secondary battery and an electronic device, which can reduce the gap between the outer ring diaphragm and the pole piece, improve the problem of full charge wrinkling of the outer ring of the negative electrode and improve the performance of the secondary battery by arranging the annular insulating tape outside the bare cell. The annular package can promote the insulativity of naked electric core, improves the security performance of secondary cell. The insulating tape covers the flat area, so that the flatness of the flat area of the bare cell can be ensured, and meanwhile, the gap between the first pole piece and the second pole piece in the corner area of the outermost coil is reduced, and lithium precipitation is prevented, so that the cycle performance of the secondary battery is improved. After the secondary battery circulates, the corners are extruded, the pole piece gaps of the first arc-shaped area and the second arc-shaped area are increased, the glue sticking of the first arc-shaped area and the second arc-shaped area can reduce the corner gaps in the later period, lithium precipitation is prevented, and the safety performance of the secondary battery is improved. The insulating tape is arranged at the second corner area of the covering part and used for extending the secondary battery in the width direction, and the insulating tape is prevented from being disconnected at the later period of secondary battery circulation due to the expansion of the bare cell, so that the stress is prevented from being concentrated at the corner, the phenomenon of lithium precipitation is further prevented, and the safety performance of the secondary battery is improved.

The foregoing description is only illustrative of the preferred embodiments of the present application and the technical principles employed, and it should be understood by those skilled in the art that the scope of the utility model in question is not limited to the specific combination of features described above, but encompasses other technical solutions which may be formed by any combination of features described above or their equivalents without departing from the inventive concept, such as the features described above and the features disclosed in the present application (but not limited to) having similar functions being interchanged.

Other technical features besides those described in the specification are known to those skilled in the art, and are not described herein in detail to highlight the innovative features of the present utility model.

Claims

1. A secondary battery, characterized by comprising:

2. The secondary battery according to claim 1, wherein the insulating tape covers the flat region and/or the insulating tape covers the first corner region.

3. The secondary battery according to claim 1, wherein the ending region of the first pole piece and/or the second pole piece is within the second corner region; and/or the number of the groups of groups,

the insulating tape is integrally arranged.

4. The secondary battery according to claim 1, wherein the flat region includes a first flat region and a second flat region disposed opposite to each other across the bare cell.

5. The secondary battery according to claim 4, wherein the insulating tape covers the straight region, the first corner region, and at least part of the second corner region.

6. The secondary battery according to claim 5, wherein the portion of the second corner region covered by the insulating tape includes a first arc-shaped region and a second arc-shaped region;

7. The secondary battery according to claim 6, wherein the central angle of the region in which the first arc-shaped region is located is 3 ° -80 °, and/or the central angle of the region in which the second arc-shaped region is located is 3 ° -80 °.

8. The secondary battery according to claim 1, further comprising a case or an aluminum plastic film, the case being an aluminum case, the case and the aluminum plastic film being provided with a housing cavity, the bare cell being disposed in the housing cavity.

9. The secondary battery according to claim 1, wherein the insulating tape is one of high temperature resistant adhesive paper, polyacrylate pressure sensitive adhesive paper, silicone pressure sensitive adhesive paper, rubber pressure sensitive adhesive paper, or polyvinylidene fluoride tape.

10. An electronic device comprising a plurality of secondary batteries according to any one of claims 1 to 9.