JP2019145199A - Cell - Google Patents

Abstract

To provide a cell capable of ensuring high safety, even upon occurrence of an internal short circuit due to sticking of a conductive material such as a nail.SOLUTION: A cell 100 includes an electrode body 10 having a positive electrode 11, a negative electrode 14, and a separator 17 placed between the positive electrode 11 and the negative electrode 14, and an outer can 20 for receiving the electrode body 10, and having the polarity of one of the positive electrode 11 or the negative electrode 14. At the outermost side of the electrode body 10, at least one electrode of a polarity different from that of the outer can 20 is placed. The electrode having the polarity different from that of the outer can 20 and located at the outermost side of the electrode body 10 has a metal foil, and an active material placed at one side of the metal foil, and the active material is not placed at the other side of the metal foil, i.e., a face at a side close to the outer can 20. The cell 100 further includes an insulation sheet 30 placed between the other face of the metal foil of the electrode having the polarity different from that of the outer can 20 and located at the outermost side of the electrode body 10, and the outer can 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a battery having a structure in which an electrode body is housed in an outer can.

  A battery having a structure in which an electrode body having a positive electrode and a negative electrode is housed in an outer can is known.

  Patent Document 1 discloses a battery having a configuration in which a plurality of stacked electrode bodies with a separator sheet interposed between a positive electrode sheet and a negative electrode sheet are accommodated in an outer can, and the opening of the outer can is sealed with a lid member. Yes. In this battery, the positive electrode sheet is electrically connected to the central terminal portion of the lid member, and the negative electrode sheet is electrically connected to the outer can. In order to prevent a short circuit between the outer can and the outermost electrode sheet, the outermost electrode sheet is a negative electrode sheet having the same polarity as the outer can.

JP-A-8-148162

  However, when a conductive material such as a nail is stabbed into the battery described in Patent Document 1, the positive electrode sheet and the negative electrode sheet inside the electrode body are short-circuited through the conductive material, so that a large Joule heat is generated inside the electrode body. However, battery safety becomes a problem.

  The present invention solves the above-described problems, and an object of the present invention is to provide a battery that can ensure high safety even when a conductive material such as a nail is stuck and an internal short circuit occurs.

  The battery of the present invention contains a positive electrode, a negative electrode, and an electrode body having a separator disposed between the positive electrode and the negative electrode, and the electrode body, and has one polarity of the positive electrode and the negative electrode An outer can, and at least one electrode having a polarity different from that of the outer can is disposed on the outermost side of the electrode body, and the outermost side of the electrode body having a polarity different from that of the outer can. The electrode located has a metal foil and an active material disposed on one surface of the metal foil, and the active material is disposed on the other surface of the metal foil, which is a surface closer to the outer can. And further comprising an insulator disposed between the other surface of the metal foil of the electrode located on the outermost side of the electrode body having a polarity different from that of the outer can, and the outer can. It is characterized by that.

  The electrode body is a stacked electrode body in which a plurality of positive electrodes and negative electrodes are alternately stacked via the separator, and an electrode having a polarity different from that of the outer can is disposed on the outermost side in the stacking direction of the stacked electrode body. It is good also as the structure currently made.

  Each of the positive electrode and the negative electrode includes a metal foil and an active material disposed on the metal foil, and the metal foil of the electrode disposed on the outermost side in the stacking direction of the stacked electrode body includes: It is good also as a structure thicker than the metal foil of the electrode arrange | positioned inside the lamination direction rather than metal foil.

  Moreover, the said electrode body is good also as a structure which is the winding electrode body by which the said positive electrode and the said negative electrode which pinched | interposed the said separator were wound.

  According to the present invention, since at least one electrode having a polarity different from that of the outer can is arranged on the outermost side of the electrode body, when a conductive material such as a nail is stuck from the outside at the position where the electrode is arranged First, a short circuit occurs between the electrode and the outer can. Since this short circuit resistance is much smaller than the internal resistance of the battery, Joule heat generated at the short circuit portion can be reduced. In addition, since a short circuit occurs first between the electrode disposed on the outermost side of the electrode body and the outer can and a short circuit current flows, a conductive material is then interposed between the positive electrode and the negative electrode inside the electrode body. Even if a short circuit occurs, a large short circuit current does not flow inside the electrode body, and Joule heat generated inside the electrode body can be reduced. Thereby, high safety can be ensured. Furthermore, the electrode disposed on the outermost side of the electrode body has no active material disposed on the other surface facing the outer can, so that the metal foil of the outermost electrode is disposed between the outer can and the outer can. First, a short circuit occurs. Since a short circuit with the outer can occurs between the metal foil, the short circuit resistance is very small and a short circuit current easily flows.

It is sectional drawing which shows the structure of the lithium ion battery in one Embodiment of this invention. It is a figure which shows the equivalent circuit when a conductive material, such as a nail, is stuck in the battery and a short circuit occurs. It is a figure which shows the relationship between the short circuit resistance at the time of a short circuit, and the emitted-heat amount of a short circuit part about the battery of resistance Ri1, and the battery of resistance Ri2. (A) is a figure which shows the time-dependent change of the voltage and temperature of a battery at the time of performing a nail penetration test with respect to the lithium ion battery in the 1st Embodiment of this invention, (b) is the conventional lithium It is a figure which shows the time-dependent change of the voltage and temperature of a battery at the time of performing a nail penetration test with respect to an ion battery. It is sectional drawing which shows the structure of the lithium ion battery in the 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the lithium ion battery in 3rd Embodiment which accommodated the winding electrode body in the armored can.

  Embodiments of the present invention will be described below, and the features of the present invention will be described more specifically. Hereinafter, a lithium ion battery will be described as an example of the battery of the present invention.

[First Embodiment]
FIG. 1 is a cross-sectional view showing a structure of a lithium ion battery 100 according to the first embodiment. The lithium ion battery 100 includes an electrode body 10, an outer can 20 that houses the electrode body 10, and an insulating sheet 30.

  The outer can 20 is made of, for example, a metal such as stainless steel, aluminum, nickel, or iron, and has one polarity of a positive electrode and a negative electrode. The outer can 20 is provided with a terminal 40 having a polarity different from that of itself. In this embodiment, the outer can 20 functions as a negative electrode terminal having a negative polarity, and the terminal 40 is described as a positive electrode terminal. The exterior can 20 which is a negative electrode terminal and the terminal 40 which is a positive electrode terminal are electrically insulated.

  The insulating sheet 30 is coated with an insulating layer on the surface of an insulating plate such as a resin or the like, a porous film, a resin tape such as polyimide, polypropylene or acrylic, or a metal foil such as an aluminum foil, a copper foil, a stainless steel foil or a nickel foil. And a film composed of an insulating ceramic such as alumina and a binder. The insulating sheet 30 may be bonded to the surface of the outer can 20 or the electrode body 10. Further, the insulating sheet 30 may be the same as the separator 17 described later.

In addition to the electrode body 10 and the insulating sheet 30, a nonaqueous electrolyte solution (not shown) is also enclosed in the outer can 20. The nonaqueous electrolytic solution includes a solute and a solvent. As the solute, for example, a Li salt such as LiPF ₆ or LiBF ₄ is preferably used. As the solvent, for example, an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) is preferably used. The electrolyte may be a liquid or a polymer.

  As shown in FIG. 1, the electrode body 10 is a laminated electrode body configured by alternately laminating a plurality of positive electrodes 11 and negative electrodes 14 via separators 17. In this specification, the direction in which the positive electrode 11 and the negative electrode 14 are laminated is referred to as a lamination direction.

  In the positive electrode 11, positive electrode active materials 13 are arranged on both surfaces of a positive electrode current collector 12 made of a metal foil such as aluminum. As the positive electrode active material 13, for example, lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or a material obtained by replacing a part of these transition metals with another metal is used. The positive electrode active material 13 may be used alone or in combination of two or more of the above materials. Such a positive electrode active material 13 is mixed with a binder, a solvent, and the like, applied to the positive electrode current collector 11, dried, and then pressed to apply the positive electrode active material 13 to the surface of the positive electrode current collector 11. It is arranged.

  In the negative electrode 14, negative electrode active materials 16 are disposed on both surfaces of a negative electrode current collector 15 made of a metal foil such as copper. Examples of the negative electrode active material 16 include carbon materials such as graphite (natural graphite, artificial graphite), hard carbon, and soft carbon, oxides such as silicon oxide, tin oxide, indium oxide, zinc oxide, and lithium oxide, Al, Si, A binary, ternary, or higher alloy of a metal such as Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La, and lithium is used. The negative electrode active material 16 may be used alone or in combination of two or more of the above materials. Such a negative electrode active material 16 is mixed with a binder, a solvent, and the like, applied to the negative electrode current collector 15, dried, and then pressed to apply the negative electrode active material 16 to the surface of the negative electrode current collector 15. It is arranged.

  The electrode disposed on the outermost side of the electrode body 10 in the stacking direction is an electrode having a polarity different from that of the outer can 20. In this embodiment, since the outer can 20 functions as a negative electrode terminal, the electrode arranged on the outermost side of the electrode body 10 is a positive electrode.

  In the positive electrode 11 x disposed on the outermost side of the electrode body 10, the positive electrode active material 13 is disposed only on one surface (one surface) of the positive electrode current collector 12. Specifically, the positive electrode active material 13 is disposed on the adjacent negative electrode 14 side surface (one surface) of both surfaces of the positive electrode current collector 12 of the positive electrode 11x, and the surface facing the outer can 20, that is, The positive electrode active material 13 is not disposed on the surface near the outer can 20 (the other surface). In addition, the thickness of the positive electrode current collector 12 of the positive electrode 11x is the same as the thickness of the positive electrode current collector 12 of the other positive electrode 11.

  All the positive electrode current collectors 12 are connected to terminals 40 that are positive electrode terminals via lead wires 18. In addition, all the negative electrode current collectors 15 are connected to an outer can 20 that is a negative electrode terminal via a lead wire 19. The negative electrode current collector 15 may be directly connected to the outer can 20 or may be electrically connected via another negative electrode terminal.

  As the separator 17, a sheet-like material is used, and for example, it is constituted by a microporous thin film made of polypropylene having excellent insulating properties. Since the separator 17 is made of a microporous thin film, lithium ions permeate the separator 17.

  In addition, the separator 17 is not limited to a sheet-like thing, The bag-like form which can accommodate the positive electrode 11 or the negative electrode 14 separately may be sufficient, and a ninety-nine fold form may be sufficient as it. It may be a winding form. The surface of the separator 17 may be covered with an inorganic particle coat layer, an adhesive layer, or the like. Moreover, the surface of the separator 17 may have adhesiveness. The separator 17 may be a single layer film made of one kind of material, or may be a composite film or a multilayer film made of one kind or two or more kinds of materials.

  The insulating sheet 30, which is an insulator, is disposed between the electrode body 10 and the outer can 20, and is disposed between the positive electrode 11 x disposed on the outermost side of the electrode body 10 and the outer can 20. More specifically, the insulating sheet 30 is disposed between the positive electrode 11x and the outer can 20 in the stacking direction. The insulating sheet 30 electrically insulates the positive electrode 11x disposed on the outermost side of the electrode body 10 and the outer can 20 that is a negative electrode terminal.

  Here, consider the case where a short circuit occurs when a conductive material such as a nail is stuck from the outside of the battery.

  FIG. 2 is a diagram showing an equivalent circuit in the case where a short circuit occurs due to a conductive material such as a nail stuck in the battery. In FIG. 2, the voltage of the battery before the short circuit is E, the current flowing at the time of the short circuit is I, the internal resistance of the battery is Ri, and the short circuit resistance is Rs. However, Ri is a resistance value measured under the condition of 25 ° C. converted into a resistance value at the temperature at the time of short circuit. Further, the heat generation amount of the battery is Wi, and the heat generation amount at the short-circuit portion is Ws.

  FIG. 3 is a diagram showing the relationship between the short-circuit resistance Rs at the time of short-circuit and the heat generation amount Ws of the short-circuit portion for the battery having the internal resistance Ri1 and the battery having the internal resistance Ri2 larger than Ri1. The amount of heat generation Ws of the short circuit portion becomes maximum when the internal resistance Ri of the battery is equal to the short circuit resistance Rs. In FIG. 3, the position where the internal resistance Ri of the battery becomes equal to the short-circuit resistance Rs is indicated by a broken line.

  Here, in the lithium ion battery 100 in this embodiment, first, a short circuit occurs between the positive electrode 11x disposed on the outermost side of the electrode body 10 and the outer can 20, so that the short circuit resistance Rs is within the battery. It becomes much smaller than the resistance Ri. Therefore, Joule heat generated at the short-circuit portion between the positive electrode 11x and the outer can 20 can be reduced. In addition, since a short circuit occurs first between the positive electrode 11x arranged on the outermost side of the electrode body 10 and the outer can 20 and a short circuit current flows, the positive electrode 11 and the negative electrode 14 inside the electrode body 10 are thereafter Even if a short circuit occurs between the electrodes, a large short-circuit current does not flow inside the electrode body 10, and Joule heat generated inside the electrode body 10 can be reduced. Furthermore, the positive electrode 11x disposed on the outermost side of the electrode body 10 does not have the positive electrode active material 13 disposed on the other surface facing the outer can 20, and thus the positive electrode collection of the positive electrode 11x disposed on the outermost side. First, a short circuit occurs between the electric body 12 and the outer can 20. Since a short circuit with the outer can 20 occurs between the positive electrode current collector 12 and the short circuit resistance, the short circuit current is easy to flow.

  Changes in the voltage and temperature of the battery over time when a nail penetration test in which a nail is inserted from the outside of the lithium ion battery 100 in this embodiment were examined. For comparison, a nail penetration test was also conducted on a conventional lithium ion battery in which an electrode having the same polarity as that of the outer can is arranged on the outermost side of the electrode body.

  FIG. 4 (a) is a diagram showing changes over time in battery voltage and temperature when a nail penetration test is performed on the lithium ion battery 100 in this embodiment. FIG. 4B is a graph showing changes in battery voltage and temperature over time when a nail penetration test is performed on a conventional lithium ion battery. In either case, a nail was stabbed at a timing of 10 (sec). FIGS. 4A and 4B also show the environmental temperature when the nail penetration test is performed.

  As shown in FIG. 4 (b), when a test for inserting a nail into a conventional lithium ion battery was performed, the polarity of the outer can and the electrode arranged on the outermost side of the electrode body is the same. No short circuit occurs, and the positive electrode and the negative electrode inside the electrode body are short-circuited. For this reason, the temperature of the battery rose to nearly 500 ° C., and ignition occurred inside the battery.

  On the other hand, in the lithium ion battery 100 in this embodiment, since a short circuit occurs between the positive electrode 11x disposed on the outermost side of the electrode body 10 and the outer can 20, a large current flows at the short circuit part, As shown to 4 (a), the voltage of a battery falls at a stretch. Thereby, the emitted-heat amount when the short circuit generate | occur | produces between the positive electrode 11 and the negative electrode 14 inside the electrode body 10 can be suppressed. Therefore, the temperature of the battery did not exceed 100 ° C. after the nail was pierced, and neither ignition nor smoke was generated.

[Second Embodiment]
In the lithium ion battery 100 according to the first embodiment, the thickness of the positive electrode current collector 12 of the positive electrode 11x arranged on the outermost side of the electrode body 10 is equal to the thickness of the positive electrode current collector 12 of the other positive electrode 11. It was the same. In the lithium ion battery 100 </ b> A according to the second embodiment, the thickness of the positive electrode current collector 12 a of the positive electrode 11 x disposed on the outermost side of the electrode body 10 is larger than the thickness of the positive electrode current collector 12 of the other positive electrode 11. It is also thickened.

  FIG. 5 is a cross-sectional view showing the structure of the lithium ion battery 100A in the second embodiment. Of the configuration of the lithium ion battery 100A shown in FIG. 5, the same components as those of the lithium ion battery 100 shown in FIG.

  In the positive electrode 11x disposed on the outermost side of the electrode body 10 in the stacking direction, the positive electrode active material 13 is disposed only on one surface (one surface) of the positive electrode current collector 12a. Specifically, the positive electrode active material 13 is disposed only on the adjacent negative electrode 14 side surface (one surface) of both surfaces of the positive electrode current collector 12a, and the surface facing the outer can 20 (the other surface). ) Is not provided with the positive electrode active material 13.

  The thickness of the positive electrode current collector 12a in the stacking direction is greater than the thickness of the positive electrode current collector 12 of the positive electrode 11 disposed on the inner side in the stacking direction than the positive electrode current collector 12a. For example, the thickness of the positive electrode current collector 12 disposed on the inner side in the stacking direction than the positive electrode current collector 12a is 5 μm to 12 μm, and the thickness of the positive electrode current collector 12a is 15 μm to 50 μm.

When the resistivity of the current collector made of metal foil is ρ, the length is L, and the cross-sectional area is S, the resistance R of the current collector is expressed by the following equation (1).
R = ρ · L / S (1)

  When the thickness of the current collector is increased, the cross-sectional area S is increased, so that the resistance R of the current collector is decreased as is apparent from the equation (1).

  That is, the resistance of the positive electrode current collector 12a can be reduced by increasing the thickness of the positive electrode current collector 12a disposed on the outermost side. Thereby, when a conductive material such as a nail is stabbed from the outside of the lithium ion battery 100A, the short-circuit resistance between the positive electrode 11x first short-circuited and the outer can 20 can be further reduced.

  As shown in FIG. 3, when the short-circuit resistance is smaller than the internal resistance of the battery, the Joule heat generated at the short-circuit portion decreases as the short-circuit resistance decreases. Therefore, in the lithium ion battery 100A in the second embodiment, when a conductive material such as a nail is stabbed, the positive electrode 11x and the outer can 20 that are short-circuited first are compared with the lithium ion battery 100 in the first embodiment. Joule heat generated between the two can be further reduced.

  Similarly to the first embodiment, a short circuit occurs first between the positive electrode 11x disposed on the outermost side of the electrode body 10 and the outer can 20 and a short circuit current flows. Even if a short circuit occurs between the positive electrode 11 and the negative electrode 14 through the conductive material, a large short-circuit current does not flow inside the electrode body 10, and the Joule heat generated inside the electrode body 10 can be reduced. it can.

  Further, by making the thickness of the positive electrode current collector 12b arranged on the outermost side thicker than the thickness of the other positive electrode current collector 12 arranged on the inner side in the stacking direction of the electrode body 10, the electrode body 10 It is possible to suppress the occurrence of warpage in the positive electrode 11b in which the positive electrode active material 13 is disposed only on one side during the formation of the film. Thereby, the lamination property of the electrode at the time of formation of the electrode body 10 can be improved.

[Third Embodiment]
In 1st and 2nd embodiment, the electrode body 10 accommodated in the armored can 20 was a laminated electrode body. In 3rd Embodiment, the electrode body accommodated in an armored can is the winding electrode body by which the positive electrode and negative electrode which pinched | interposed the separator were wound.

  FIG. 6 is a cross-sectional view showing a structure of a lithium ion battery 100B in the third embodiment having a configuration in which the wound electrode body 10b is housed in the outer can 20. The wound electrode body 10b is configured by winding a positive electrode 11b and a negative electrode 14b sandwiching a separator 17b therebetween in a spiral shape. The positive electrode 11b is formed by coating a positive electrode active material on both surfaces of a positive electrode current collector made of a metal foil such as aluminum, and the negative electrode 14b is made of a negative electrode current collector made of a metal foil such as copper. It is formed by coating a negative electrode active material on both sides. In FIG. 6, the positive electrode active material and the negative electrode active material are omitted.

  Further, FIG. 6 shows a configuration in which the winding end surface (the surface in which the winding state is understood) of the wound electrode body 10b is stored without matching the surface on which the terminal 40 of the outer can 20 is formed. The form is not limited to this. It is also possible to store the wound end face of the wound electrode body 10b so as to coincide with the face on which the terminal 40 of the outer can 20 is formed. In this case, the terminal 40 and the electrode body 10 are electrically connected by a separate connection lead.

  Also in this embodiment, the outer can 20 is a negative electrode terminal and the terminal 40 is a positive electrode terminal. Therefore, the positive electrode 11 b is electrically connected to the terminal 40, and the negative electrode 14 b is electrically connected to the outer can 20.

  Similar to the first and second embodiments, the electrode located on the outermost side of the wound electrode body 10 b is an electrode having a polarity different from that of the outer can 20. Therefore, the electrode located on the outermost side of the wound electrode body 10b is the positive electrode 11b. An insulating sheet 30 is disposed between the electrode 11b, which is an electrode located on the outermost side of the wound electrode body 10b, and the outer can 20.

  Also in the lithium ion battery 100B in the third embodiment, when a conductive material such as a nail is stabbed from the outside, the positive electrode 11b and the outer can 20 that are located on the outermost side of the wound electrode body 10 are interposed through the conductive material. First, a short circuit occurs first, so that, similarly to the first and second embodiments, Joule heat generated inside the wound electrode body 10b can be reduced, and high safety can be ensured. .

  Here, in the first and second embodiments described above, it has been described that the two electrodes arranged on the outermost side of the electrode body 10 in the stacking direction are electrodes having polarities different from those of the outer can 20. However, only one of the two electrodes arranged on the outermost side of the electrode body 10 in the stacking direction may be an electrode having a polarity different from that of the outer can 20. For example, when the battery according to the present invention is housed in an electronic device and used, only the electrode close to the outside of the electronic device out of the two electrodes arranged on the outermost side of the electrode body in the stacking direction is packaged. The electrode can have a polarity different from that of the can. Also in this case, when a conductive material such as a nail is stabbed from the outside of the electronic device, Joule heat generated inside the battery can be reduced, and high safety can be ensured.

  In each embodiment described above, the outer can 20 is a negative electrode terminal and the terminal 40 is a positive electrode terminal. However, the outer can 20 may be a positive electrode terminal and the terminal 40 may be a negative electrode terminal. In that case, the electrode arranged on the outermost side of the electrode body 10 is a negative electrode.

  In the above-described embodiment, the lithium ion battery has been described as an example, but a battery other than the lithium ion battery may be used.

  According to the battery of the present invention, since at least one electrode having a polarity different from that of the outer can is disposed on the outermost side of the electrode body, a conductive material such as a nail is externally provided at the position where the electrode is disposed. When stabbed, a short circuit first occurs between the electrode and the outer can. Since this short circuit resistance is much smaller than the internal resistance of the battery, Joule heat generated at the short circuit portion can be reduced. In addition, since a short circuit occurs first between the electrode disposed on the outermost side of the electrode body and the outer can and a short circuit current flows, a conductive material is then interposed between the positive electrode and the negative electrode inside the electrode body. Even if a short circuit occurs, a large short circuit current does not flow inside the electrode body, and Joule heat generated inside the electrode body can be reduced. Thereby, high safety can be ensured.

  The electrode body is a laminated electrode body in which a plurality of positive electrodes and negative electrodes are alternately laminated via separators, and an electrode having a polarity different from that of the outer can is disposed on the outermost side in the laminating direction of the laminated electrode body. Thus, even if a conductive material such as a nail is pierced from either of the two outer sides in the stacking direction, Joule heat generated inside the electrode body can be reduced, and high safety can be ensured. it can.

  Each of the positive electrode and the negative electrode has a metal foil and an active material disposed on the metal foil, and the metal foil of the electrode disposed on the outermost side in the stacking direction of the stacked electrode body is more than the metal foil. By making the structure thicker than the metal foil of the electrode arranged on the inner side in the stacking direction, the resistance of the metal foil of the electrode arranged on the outermost side can be reduced. As a result, the short-circuit resistance between the outermost electrode and the outer can that is short-circuited first can be further reduced, and the Joule heat generated at the short-circuit portion can be reduced.

  Further, even when the electrode body is a wound electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, a joule generated inside the electrode body when a conductive material such as a nail is stabbed from the outside. Heat can be reduced and high safety can be ensured.

  The present invention is not limited to the above-described embodiment in other points, and various applications and modifications can be made within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10, 10b Electrode body 11, 11b Positive electrode 11x Positive electrode 12, 12a arrange | positioned on the outermost side Positive electrode collector 13 Positive electrode active material 14 Negative electrode 15 Negative electrode collector 16 Negative electrode active material 17 Separator 20 Outer can 30 Insulation sheet 40 Terminal 100, 100A, 100B lithium ion battery

Claims (4)

An electrode body having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode;
An outer can that houses the electrode body and has one polarity of the positive electrode and the negative electrode;
With
At least one electrode having a polarity different from that of the outer can is disposed on the outermost side of the electrode body,
The electrode that has a polarity different from that of the outer can and is positioned on the outermost side of the electrode body includes a metal foil and an active material disposed on one surface of the metal foil, on the side close to the outer can No active material is disposed on the other surface of the metal foil that is a surface,
An insulator disposed between the outer can and the other surface of the metal foil of the electrode having the polarity different from that of the outer can and positioned on the outermost side of the electrode body;
A battery characterized by that. The electrode body is a laminated electrode body in which a plurality of the positive electrodes and the negative electrodes are alternately laminated via the separator,
On the outermost side in the stacking direction of the stacked electrode body, an electrode having a polarity different from that of the outer can is disposed,
The battery according to claim 1. Each of the positive electrode and the negative electrode has a metal foil and an active material disposed on the metal foil,
The metal foil of the electrode arranged on the outermost side in the lamination direction of the laminated electrode body is thicker than the metal foil of the electrode arranged on the inner side in the lamination direction than the metal foil,
The battery according to claim 2. The electrode body is a wound electrode body in which the positive electrode and the negative electrode sandwiched between the separators are wound.
The battery according to claim 1.

Images