WO2018100927A1

WO2018100927A1 - Secondary cell and device

Info

Publication number: WO2018100927A1
Application number: PCT/JP2017/038555
Authority: WO
Inventors: 昌史樋口; 徹川合; 優佐々木
Original assignee: 株式会社村田製作所
Priority date: 2016-11-29
Filing date: 2017-10-25
Publication date: 2018-06-07

Abstract

The present invention provides a secondary cell which achieves an even smaller size and greater capacity through efficient use of dead space based on a sealed section on the longest side of the plan-view profile of a conventional secondary cell. The present invention relates to a secondary cell 100A in which an electrode assembly, including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and an electrolyte are sealed inside an outer case, wherein the secondary cell 100A has a shape provided with a notch 8A in plan-view, and the outer case 6 is constituted by a sheet folded back along a longest side 70 of the plan-view profile of the secondary cell 100A.

Description

Secondary battery and device

The present invention relates to a secondary battery and a device.

Conventionally, secondary batteries have been used as power sources for various electronic devices. A secondary battery generally has a structure in which an electrode assembly (electrode body) and an electrolyte are accommodated in an exterior body (case), and further includes an external terminal for achieving electrical connection of the secondary battery. (For example, Patent Document 1).

In recent years, electronic devices are becoming thinner and smaller, and accordingly, demands for thinner and smaller secondary batteries are increasing. The secondary battery is generally used together with a substrate, for example, an electronic circuit substrate such as a printed circuit board, a semiconductor substrate such as a silicon wafer, and a glass substrate such as a display panel. In particular, the protection circuit board is often used in lithium ion secondary batteries for the purpose of preventing overcharge, overdischarge and overcurrent.

For this reason, a technique has been reported in which a notch is provided in a secondary battery and a substrate is arranged there (Patent Document 2). Specifically, as shown in FIG. 10A, for example, the secondary battery 500 has a shape provided with a notch 508, and a seal for holding an electrolyte or the like in the exterior body 506 at the entire peripheral edge of the shape. Parts 509a to 509h. In such a secondary battery 500, generally, as shown in FIG. 10B, the substrate 600 is notched from the peripheral part (

seal part

509a, 509b, 509c) of the secondary battery 500 through a predetermined gap x. It is arranged in the department. The seal portion is formed by heat sealing when the outer package 506 is a flexible pouch made of, for example, a laminate film.

JP2015-518256A JP 2016-506606 A

However, the inventors of the present invention have found that such a secondary battery 500 causes the following new problems. Since the upper part and / or the lower part of the seal part in the thickness direction of the secondary battery 500 is a dead space, the size of the secondary battery is increased due to the presence of the seal part, and the energy density of the secondary battery is lowered. In particular, the formation of a dead space was remarkable in the seal part of the longest side in the outline of the planar view of the secondary battery.

On the other hand, since the gap x between the secondary battery and the substrate also becomes a dead space for the secondary battery, the energy density of the secondary battery is also lowered, which is disadvantageous for downsizing and increasing the capacity of the secondary battery. there were.

The present invention is a secondary battery that achieves further miniaturization and / or high capacity by effectively using a dead space based on the seal part of the longest side in the outline of the shape of the conventional secondary battery in plan view. It is a first object to provide

The present invention reduces the size and / or size by effectively using the dead space based on the seal portion of the longest side in the contour of the planar view shape of the conventional secondary battery and the dead space between the conventional secondary battery and the substrate. A second object is to provide a secondary battery that can sufficiently achieve a higher capacity.

The present invention
An electrode assembly including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and a secondary battery in which an electrolyte is enclosed in an exterior body,
The secondary battery has a shape with a notch in plan view,
The said exterior body is related with the secondary battery comprised from the sheet | seat folded by the longest side in the outline of the planar view shape which the said secondary battery has.

Since the secondary battery of the present invention effectively uses the dead space based on the seal portion of the longest side in the outline of the plan view shape of the conventional secondary battery, it is possible to further reduce the size and / or increase the capacity. Can be achieved. For this reason, the energy density of the secondary battery of the present invention is further improved sufficiently.

The typical top view when the secondary battery which concerns on the 1st embodiment of this invention is seen from the thickness direction is shown. FIG. 1B is a schematic plan view of a device showing an example of a preferable arrangement of the secondary battery and the substrate in FIG. 1A. The typical perspective view of the sheet | seat for demonstrating the usage condition of a sheet | seat when forming the exterior body of the secondary battery of FIG. 1A is shown. The typical top view when the secondary battery which concerns on the 2nd embodiment of this invention is seen from the thickness direction is shown. The typical top view of the device showing an example of the desirable arrangement of the secondary battery and substrate of Drawing 2A is shown. The typical top view when the secondary battery which concerns on the 3rd embodiment of this invention is seen from the thickness direction is shown. The typical top view of the device showing an example of the desirable arrangement of the secondary battery of Drawing 3A and a substrate is shown. The typical top view when the secondary battery which concerns on the 4th embodiment of this invention is seen from the thickness direction is shown. The typical top view of the device showing an example of the desirable arrangement of the secondary battery and substrate of Drawing 4A is shown. The typical top view when the secondary battery which concerns on the 5th embodiment of this invention is seen from the thickness direction is shown. The typical top view of the device showing an example of the desirable arrangement of the secondary battery and substrate of Drawing 5A is shown. The typical top view when the secondary battery which concerns on the 6th embodiment of this invention is seen from the thickness direction is shown. The typical top view of the device showing an example of the desirable arrangement of the secondary battery and substrate of Drawing 6A is shown. The typical top view when the secondary battery which concerns on the 7th embodiment of this invention is seen from the thickness direction is shown. The typical top view of the device showing an example of the desirable arrangement of the secondary battery of Drawing 7A and a substrate is shown. It is a typical sectional view of a device for explaining an example of a structure of a secondary battery. It is a typical sectional view of a device for explaining another example of the structure of a secondary battery. The typical perspective view of the sheet | seat for demonstrating the usage form of a sheet | seat when forming the exterior body of the secondary battery of this invention which has the structure of FIG. 8A is shown. The typical top view when the secondary battery which concerns on a prior art is seen from the thickness direction is shown. FIG. 10B is a schematic plan view of a device representing the arrangement of the secondary battery and the substrate of FIG. 10A.

[Secondary battery]
The present invention provides a secondary battery. In this specification, the term “secondary battery” refers to a battery that can be repeatedly charged and discharged. The “secondary battery” is not excessively bound by the name, and may include, for example, “electric storage device”.

In the secondary battery of the present invention, an electrode assembly and an electrolyte, which will be described later, are sealed in an exterior body, and a sealing portion (sealing) for holding the electrolyte and the like inside the exterior body is provided at a predetermined peripheral edge in a plan view. Part) is formed. The plan view is a state when the secondary battery is placed and viewed from directly above in the thickness (height) direction, and is in agreement with the plan view. The mounting is, for example, mounting with the surface of the maximum area of the secondary battery as the bottom surface.

Hereinafter, the secondary battery of the present invention will be described in detail with reference to the drawings, but various elements in the drawings are merely schematically and exemplarily shown for understanding of the present invention, and the appearance and size ratio, etc. Can be different from the real thing. The “vertical direction”, “left / right direction”, and “front / back direction” used directly or indirectly in this specification correspond to directions corresponding to the vertical direction, left / right direction, and front / back direction in the drawing, respectively. Unless otherwise specified, the same symbols or symbols indicate the same members or the same meaning.

The secondary battery of the present invention has a notch portion in plan view as shown in FIGS. 1A, 2A, 3A, 4A, 5A, 6A and 7A (hereinafter referred to as FIGS. 1A to 7A). 8 (including 8A, 8B, 8C, 8D, 8E, 8F and 8G). The notch is a part where a part of the cutout is intentionally lost from the initial shape. The initial shape of the secondary battery before the formation of the notch is usually a quadrangular shape (particularly a rectangular shape). The rectangular shape includes so-called rectangles and squares, and is preferably rectangular. The secondary battery before the formation of the notch is a secondary battery when it is assumed that there is no notch. 1A to 7A are schematic plan views of an example of a secondary battery according to the present invention as viewed from the thickness direction.

The boundary line 7 between the secondary battery 100 (including 100A, 100B, 100C, 100D, 100E, 100F, and 100G) and the notch 8 includes one or more straight lines, one or more curves, or a combination thereof. It's okay. For example, in FIG. 1A, the boundary line 7 includes four straight lines. Further, for example, in FIG. 2A and FIG. 3A, the boundary line 7 includes two straight lines. For example, in FIG. 4A, the boundary line 7 includes one straight line. Further, for example, in FIG. 5A, the boundary line 7 includes one straight line and one curved line. For example, in FIG. 6A and FIG. 7A, the boundary line 7 includes one curve. The curve includes an arc-shaped curve, a parabolic curve, any other curve, and a curve in which a plurality of these curves are continuously connected.

The arrangement of the notches 8 included in the secondary battery is not particularly limited as long as it is appropriately selected according to the desired arrangement of the substrate. For example, the notch 8 may be arranged so as to share one or more and two or less sides with the secondary battery before forming the notch, or not to share any one side. From the viewpoint of the balance between the downsizing of the module including the secondary battery and the circuit board and the increase in capacity of the secondary battery, the arrangement of the notch portion 8 is preferably the secondary battery before the notch portion 8 is formed. And one or two, especially two sides are shared.

The arrangement in which the notch 8 shares two sides with the secondary battery before the notch is formed is an arrangement in which the notch 8 has one corner shared with the secondary battery. It means that the notch 8 has a shape including a corner in the secondary battery and is in a corner arrangement. The shape of the notch 8 is not particularly limited. For example, the L-shape shown in FIG. 1A, the quadrangular shape (particularly rectangular shape) shown in FIGS. 2A and 3A, the triangular shape shown in FIG. Examples include a substantially trapezoidal shape shown in 5A and a substantially triangular shape shown in FIG. 7A.

The arrangement in which the cutout portion 8 shares one side with the secondary battery before the cutout portion is formed is an arrangement in which the cutout portion 8 has only one side shared with the secondary battery. It means that the notch 8 has a shape that does not include a corner in the secondary battery and is in an end portion arrangement. The shape of the notch 8 is not particularly limited, and examples thereof include a quadrangular shape (particularly a rectangular shape).

The arrangement in which the cutout portion 8 does not share any side with the secondary battery before the cutout portion is formed is an arrangement in which the cutout portion 8 does not have any side shared with the secondary battery. Yes, it means that the notch 8 has a shape including neither a corner nor a side in the secondary battery, and is in a central arrangement. The shape of the notch 8 is not particularly limited, and examples thereof include a circular shape and a quadrangular shape (particularly a rectangular shape) shown in FIG. 6A.

The exterior body 6 is composed of a sheet that is folded back at the longest side in the outline of the planar view of the secondary battery 100. That is, the exterior body 6 is configured such that the linear folded portion formed by folding the sheet becomes the longest side in the contour of the planar view of the secondary battery. For example, as shown in FIG. 1C, a sheet corresponding to the upper exterior member 6 a and the lower exterior member 6 b of the exterior body 6, and a linear folded portion formed by folding a continuous sheet is formed. The exterior body 6 is formed by folding back so as to be the longest side 70 in the outline of the secondary battery in plan view. The outline of the planar view shape is a line of the outer edge that forms the outline in the planar view shape of the secondary battery. The longest side in the outline of the plan view shape is a line segment having the longest straight line shape among the lines of the outer edge forming such an outline. If there are two or more longest sides, one longest side may be selected from them. A line segment is a straight line between two points. FIG. 1C is a schematic perspective view of a sheet for explaining how the sheet is used when forming the outer package of the secondary battery in FIG. 1A.

By forming the exterior body by folding the sheet at the longest side in the outline of the planar view of the secondary battery 100 as described above, the seal portion is formed in the longest side portion of the outline of the secondary battery in the planar view shape. It can be avoided. Thereby, formation of the dead space based on the said seal part is avoided. Therefore, the secondary battery can be reduced in size by the dead space, and / or the electrode assembly can be enlarged in the outer package to increase the capacity, and as a result, the secondary battery can be achieved. It is possible to sufficiently improve the energy density. The energy density (Wh / L) of the secondary battery is one parameter indicating the battery performance obtained by dividing the energy capacity (W / h) of the battery by the battery volume (L).

The sheet only needs to be non-permeable so as to prevent permeation of the electrolyte, and is preferably a soft sheet having such non-permeability and flexibility enough to achieve free bending of the sheet, more preferably Is a plastic sheet. As the sheet, any sheet used as a sheet constituting the outer package in the field of secondary batteries can be used. As the soft sheet, for example, any soft sheet used as a sheet constituting a flexible pouch in the field of secondary batteries can be used. The plastic sheet is a sheet having a characteristic that the deformation due to the external force is maintained when the external sheet is applied and then removed. For example, a so-called laminate film can be used. An exterior body composed of a soft sheet or a plastic sheet is called a flexible pouch (soft bag body). In particular, a flexible pouch made of a laminate film can form a seal portion by, for example, heat sealing an overlapped portion of the laminate film. As the laminate film, a film obtained by laminating a metal foil and a polymer film is generally used. Specifically, a film having a three-layer structure including an outer layer polymer film / metal foil / inner layer polymer film is exemplified. The outer layer polymer film is for preventing damage to the metal foil due to permeation and contact of moisture and the like, and polymers such as polyamide and polyester can be suitably used. The metal foil is for preventing the permeation of moisture and gas, and a foil of copper, aluminum, stainless steel or the like can be suitably used. The inner layer polymer film is for protecting the metal foil from the electrolyte accommodated therein, and for melting and sealing at the time of heat sealing, and polyolefin or acid-modified polyolefin can be suitably used. The thickness of the laminate film is not particularly limited, and is preferably 1 μm or more and 1 mm or less, for example.

The secondary battery 100 does not have a seal portion at the peripheral edge adjacent to the longest side 70 among the peripheral edges in the planar view shape of the secondary battery. The peripheral edge adjacent to the longest side 70 has been sealed inside by the folding back of the exterior body 6, so that it is not necessary to form a seal portion. The peripheral edge in the plan view shape of the secondary battery is a peripheral area at the outer peripheral edge in the plan view shape of the secondary battery, for example, 90a to 90h in FIG. 1A and the peripheral edge 91a to FIG. 2A. 91f, peripheral portions 92a to 92f in FIG. 3A, peripheral portions 93a to 93e in FIG. 4A, peripheral portions 94a to 94e in FIG. 5A, peripheral portions 95a to 95e in FIG. 6A, and peripheral portions 96a to 96e in FIG. The peripheral edge adjacent to the longest side 70 is a rectangular peripheral edge including the longest side 70 as one side among the peripheral edges in the planar view shape of the secondary battery. For example, the peripheral edge in FIG. 1A 90g, peripheral edge 91e in FIG. 2A, peripheral edge 92e in FIG. 3A, peripheral edge 93d in FIG. 4A, peripheral edge 94d in FIG. 5A, peripheral edge 95d in FIG. 6A, peripheral edge 96c in FIG. The peripheral edge adjacent to the longest side 70 does not include a region common to the adjacent peripheral edge that is continuous with the peripheral edge. In FIG. 1A to FIG. 7A, since the secondary battery 100 does not have a seal portion at the peripheral edge adjacent to the longest side 70, the peripheral edge is not shown as a hatched area.

The secondary battery 100 normally has a seal portion at a peripheral edge other than the peripheral edge adjacent to the longest side among the peripheral edges in the planar view shape of the secondary battery. Peripheral parts other than the peripheral part adjacent to the longest side are all peripheral parts other than the peripheral part adjacent to the longest side among the peripheral parts in the plan view shape of the secondary battery. For example, in FIG. 1A Peripheral parts 90a to 90f and 90h, peripheral parts 91a to 91d and 91f in FIG. 2A, peripheral parts 92a to 92d and 92f in FIG. 3A, peripheral parts 93a to 93c and 93e in FIG. 4A, peripheral parts 94a to 94c in FIG. 94e, peripheral portions 95a to 95c and 95e in FIG. 6A, and peripheral portions 96a to 96b and 96d to 96e in FIG. 7A. In FIG. 1A to FIG. 7A, since the peripheral portion has a seal portion, the peripheral portion is shown as a hatched area. Having a seal portion means that sealing inside the exterior body is achieved at a predetermined peripheral edge.

The secondary battery 100 has a line segment connected to the longest side 70 as an outline of the planar view shape of the secondary battery 100. The line segment connected to the longest side 70 is a line segment combined with the longest side 70 in the outline (line) in the planar view shape of the secondary battery 100, and is usually connected to one end of the longest side 70. It is a line segment. Examples of line segments connected to the longest side 70 include, for example,

line segments

71a and 71b in FIG. 1A,

line segments

72a and 72b in FIG. 2A,

line segments

73a and 73b in FIG. 3A, and

line segments

74a and 74b in FIG. 5A,

line segments

75a and 75b in FIG. 6A, and

line segments

77a and 77b in FIG. 7A.

In the secondary battery 100, among the seal portions of the secondary battery 100, the peripheral seal portion adjacent to the line segment connected to the longest side 70 can be bent in the thickness direction of the secondary battery. The peripheral edge portion adjacent to the line segment connected to the longest side 70 is a peripheral edge portion including the above-described line segment connected to the longest side 70 as one side. For example, the

peripheral edge portions

90f and 90h in FIG. ),

Peripheral edges

91d and 91f (shaded area) in FIG. 2A,

peripheral edges

92d and 92f (shaded area) in FIG. 3A,

peripheral edges

93c and 93e (shaded area) in FIG. 4A,

peripheral edges

94c and 94e in FIG. (Shaded area), peripheral edges 95c and 95e (shaded area) in FIG. 6A, and

peripheral edges

96b and 96d (hatched area) in FIG. 7A.

The seal part at the peripheral edge adjacent to the line segment connected to the longest side 70 can be bent in the thickness direction of the secondary battery. The seal part has a linear shape as a whole, and an external terminal described later It means not having 5. By folding the seal part in the thickness direction of the secondary battery, the secondary battery can be reduced in size by the amount of the seal part and / or the electrode assembly can be enlarged in the exterior body to increase the capacity. As a result, the energy density of the secondary battery can be further improved.

The bending direction is not particularly limited as long as the secondary battery can be reduced in size and / or increased in capacity. For example, the bending direction may be either the upward direction or the downward direction in the thickness direction of the secondary battery. The folded seal part may be coupled to a so-called main body part of the secondary battery or may not be coupled. However, the folded seal part is at least partially from the viewpoint of further miniaturization and / or high capacity of the secondary battery by effective utilization of the dead space, by a bonding means such as an adhesive, an adhesive tape, etc. It is preferable to be coupled to the main body.

In the present invention, the secondary battery 100 includes the secondary battery 100 and a cutout portion of the seal portion of the secondary battery from the viewpoint of further downsizing and / or increasing the capacity of the secondary battery by effectively using the dead space. 8 is a substrate 60 (60A, 60B, 60C, 60D, 60E, 60F) at least partly, preferably all of the seal part of the peripheral part adjacent to the boundary line 7 (hereinafter also referred to as “boundary peripheral part”). It is preferable that the first and second end portions overlap with each other. The boundary peripheral edge is a peripheral edge including the boundary line as one side. For example, the peripheral edge 90a to 90d in FIG. 1A, the peripheral edge 91a to 91b in FIG. 2A, the peripheral edge 92a to 92b in FIG. Examples include a peripheral portion 93a in 4A, a peripheral portion 94a in FIG. 5A, a peripheral portion 95a in FIG. 6A, and a peripheral portion 96a in FIG. 7A. The fact that at least a part of the sealing part at the boundary peripheral part overlaps with the end part of the substrate means that at least a part of the sealing part at the peripheral peripheral part of the secondary battery when the secondary battery and the substrate arranged in a plan view are seen through. And the end of the substrate overlap. For example, in FIGS. 1B, 2B, 3B, 4B, 5B, 6B, and 7B (hereinafter referred to as FIGS. 1B to 7B), a part of the seal at the peripheral edge of the secondary battery 100 The end of the substrate 60 overlaps. Thereby, formation of a dead space between a secondary battery and a board | substrate is avoided. Therefore, the secondary battery can be reduced in size by the dead space, and / or the electrode assembly can be enlarged in the outer package to increase the capacity, and as a result, the secondary battery can be achieved. The energy density can be further improved sufficiently. 1B to 7B are schematic plan views of devices showing examples of preferred arrangements of the secondary battery and the substrate of FIGS. 1A to 7A, respectively.

The ratio of the overlapping area due to the substrate in the seal portion at the peripheral edge of the boundary is usually 50% or more, preferably 60% or more, more preferably 70% or more. The ratio of the overlapping area is a ratio with respect to the total area of the seal portion at the boundary peripheral portion. The area of the common part of the seal part of the boundary peripheral part and the seal part other than the seal part of the boundary peripheral part is included in the area of the seal part of the boundary peripheral part. In addition, the area of the boundary peripheral part 96a of FIG. 7A is taken as the area between curves.

The external terminal 5 usually includes a positive electrode external terminal and a negative electrode external terminal, and is electrically connected to a substrate disposed in the notch. The two external terminals 5 may be independently provided so as to protrude from any seal portion. The two external terminals 5 are shown in FIGS. 1A, 2A, 3A, 4A, 5A, and 6A from the viewpoint of further downsizing and / or increasing the capacity of the secondary battery by effectively using the dead space. Thus, it is preferable to be provided so as to protrude from the seal portion other than the seal portion at the peripheral edge adjacent to the line segment connected to the longest side 70. This is because if the external terminal is provided at the seal portion at the peripheral edge adjacent to the line segment connected to the longest side 70, the seal portion is not normally bent from the viewpoint of sealing performance.

As shown in FIGS. 2A, 3A, 4A, 5A, and 6A, the two external terminals 5 are notched from the sealing portion at the boundary peripheral edge from the viewpoint of reducing the resistance between the secondary battery and the substrate. It is preferable that the projection is provided toward the portion 8. Thereby, since the wiring between a secondary battery and a board | substrate can be shortened, the resistance between a secondary battery and a board | substrate can be reduced, and the heat_generation | fever and electric power loss by wiring resistance can fully be prevented.

The width w1 of the seal portion from which the external terminal 5 protrudes is usually 0.1 × D to 3 × D, particularly 0.2 × D to D, with respect to the thickness (height) D (mm) of the secondary battery. It is. The width w2 of the seal portion other than the seal portion from which the external terminal 5 protrudes is usually 0.05 × D to 2 × D, particularly 0.1 × D to D, with respect to the thickness D (mm) of the secondary battery. It is. From the viewpoint of preventing leakage of the electrolyte, the width w1 and the width w2 preferably satisfy the relationship of w1 ≧ w2, particularly w1> w2, and more preferably satisfy the relationship of 3 × w2 ≧ w1> w2.

The secondary battery 100 (especially the sealing portion at the boundary peripheral edge) and the substrate 60 may or may not be coupled to each other at some or all of their contact portions. From the viewpoint of prevention, they are preferably bonded. The coupling means is not particularly limited, and for example, a coupling means such as an adhesive or an adhesive tape may be used.

In FIG. 1B to FIG. 7B, as shown in FIG. 8A, the overlap between the sealing portion at the boundary edge of the secondary battery 100 and the substrate 60 is such that the end of the substrate 60 is placed on the sealing portion 98 at the boundary periphery. It is achieved by being arranged. The overlap may be achieved by placing the end of the substrate 60 under the seal portion 98. In FIG. 8A, only the upper exterior member 6a constituting the exterior body 6 is a cup molded body having a thickness, but is not limited thereto. For example, both the upper exterior member 6a and the lower exterior member 6b may not have a thickness, or only the lower exterior member 6b may be a cup molded body having a thickness, or According to the thickness (height) of the electrode assembly housed in the secondary battery, as shown in FIG. 8B, both the upper exterior member 6a and the lower exterior member 6b are cup molded bodies having thicknesses. Also good.

8A, when only the upper exterior member 6a constituting the exterior body 6 is a cup molded body having a thickness, the exterior body 6 is configured as follows. For example, as shown in FIG. 9, after performing cup molding only on a portion corresponding to the upper exterior member 6a of the exterior body 6 in one sheet, this one sheet (particularly a soft sheet) is formed by folding. The outer folded body 6 is configured such that the straight folded portion is the longest side 70 in the outline of the secondary battery in plan view.

[Other components of secondary battery]
For example, as shown in FIGS. 8A and 8B, the electrode assembly includes a positive electrode 1, a negative electrode 2, and a separator 3, and the positive electrode 1 and the negative electrode 2 are alternately arranged via the separator 3. The two external terminals are usually connected to an electrode (positive electrode or negative electrode) via a current collecting lead, and as a result, are led out from the seal portion. In these drawings, the electrode assembly has a planar laminated structure in which a plurality of electrode units (electrode constituent layers) including a positive electrode 1, a negative electrode 2, and a separator 3 arranged between the positive electrode 1 and the negative electrode 2 are laminated in a planar shape. have. The structure of the electrode assembly is not limited to a planar laminated structure. For example, an electrode unit (electrode constituent layer) including a positive electrode 1, a negative electrode 2, and a separator 3 disposed between the positive electrode 1 and the negative electrode 2 is wound in a roll shape. You may have a wound structure (jelly roll type). For example, the electrode assembly may have a so-called stack and folding structure in which a positive electrode, a separator, and a negative electrode are stacked on a long film and then folded.

The positive electrode 1 is composed of at least a positive electrode material layer and a positive electrode current collector (foil), and it is sufficient that the positive electrode material layer is provided on at least one surface of the positive electrode current collector. For example, in the positive electrode 1, a positive electrode material layer may be provided on both surfaces of the positive electrode current collector, or a positive electrode material layer may be provided on one surface of the positive electrode current collector. The positive electrode 1 preferable from the viewpoint of further increasing the capacity of the secondary battery is provided with a positive electrode material layer on both surfaces of the positive electrode current collector. The positive electrode material layer contains a positive electrode active material.

The negative electrode 2 is composed of at least a negative electrode material layer and a negative electrode current collector (foil), and it is sufficient that the negative electrode material layer is provided on at least one surface of the negative electrode current collector. For example, in the negative electrode 2, the negative electrode material layer may be provided on both surfaces of the negative electrode current collector, or the negative electrode material layer may be provided on one surface of the negative electrode current collector. From the viewpoint of further increasing the capacity of the secondary battery, the negative electrode 2 is preferably provided with a negative electrode material layer on both surfaces of the negative electrode current collector. The negative electrode material layer contains a negative electrode active material.

The positive electrode active material included in the positive electrode material layer and the negative electrode active material included in the negative electrode material layer are materials directly involved in the transfer of electrons in the secondary battery, and are the main materials of the positive and negative electrodes that are responsible for charge / discharge, that is, the battery reaction. is there. More specifically, ions are brought into the electrolyte due to the “positive electrode active material included in the positive electrode material layer” and the “negative electrode active material included in the negative electrode material layer”, and the ions are interposed between the positive electrode and the negative electrode. Then, the electrons are transferred and the electrons are delivered and charged and discharged. As will be described later, the positive electrode material layer and the negative electrode material layer are particularly preferably layers capable of occluding and releasing lithium ions. That is, a secondary battery in which lithium ions move between the positive electrode and the negative electrode through the electrolyte to charge and discharge the battery is preferable. When lithium ions are involved in charging / discharging, the secondary battery according to this embodiment corresponds to a so-called “lithium ion battery”.

The positive electrode active material of the positive electrode material layer is made of, for example, a granular material, and a binder (also referred to as a “binder”) is included in the positive electrode material layer for sufficient contact between the particles and shape retention. preferable. Furthermore, it is also preferable that a conductive additive is included in the positive electrode material layer in order to facilitate the transmission of electrons that promote the battery reaction. Similarly, the negative electrode active material of the negative electrode material layer is made of, for example, a granular material, and it is preferable that a binder is included for sufficient contact and shape retention between the particles, and smooth transmission of electrons that promote the battery reaction. In order to do so, a conductive aid may be included in the negative electrode material layer. Thus, because of the form in which a plurality of components are contained, the positive electrode material layer and the negative electrode material layer can also be referred to as “positive electrode composite material layer” and “negative electrode composite material layer”, respectively.

The positive electrode active material is preferably a material that contributes to occlusion and release of lithium ions. From this point of view, the positive electrode active material is preferably, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material is preferably a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese, and iron. That is, in the positive electrode material layer of the secondary battery according to this embodiment, such a lithium transition metal composite oxide is preferably included as a positive electrode active material. For example, the positive electrode active material may be lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or a part of those transition metals replaced with another metal. Although such a positive electrode active material may be included as a single species, two or more types may be included in combination. In a more preferred embodiment, the positive electrode active material contained in the positive electrode material layer is lithium cobalt oxide.

The binder that can be included in the positive electrode material layer is not particularly limited, but includes polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, and Mention may be made of at least one selected from the group consisting of polytetrafluoroethylene and the like. The conductive auxiliary agent that can be included in the positive electrode material layer is not particularly limited, but carbon black such as thermal black, furnace black, channel black, ketjen black, and acetylene black, graphite, carbon nanotube, and vapor phase growth. Examples thereof include at least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives. In a more preferred aspect, the binder of the positive electrode material layer is polyvinylidene fluoride, and in another more preferred aspect, the conductive additive of the positive electrode material layer is carbon black. In a more preferred embodiment, the binder and conductive additive of the positive electrode material layer are a combination of polyvinylidene fluoride and carbon black.

The negative electrode active material is preferably a material that contributes to occlusion and release of lithium ions. From this point of view, the negative electrode active material is preferably, for example, various carbon materials, oxides, or lithium alloys.

Examples of various carbon materials of the negative electrode active material include graphite (natural graphite, artificial graphite), hard carbon, soft carbon, diamond-like carbon, and the like. In particular, graphite is preferable in that it has high electron conductivity and excellent adhesion to the negative electrode current collector. Examples of the oxide of the negative electrode active material include at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, lithium oxide, and the like. The lithium alloy of the negative electrode active material may be any metal that can be alloyed with lithium. For example, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, It may be a binary, ternary or higher alloy of a metal such as La and lithium. Such an oxide is preferably amorphous in its structural form. This is because deterioration due to non-uniformity such as crystal grain boundaries or defects is less likely to be caused. In a more preferred embodiment, the negative electrode active material of the negative electrode material layer is artificial graphite.

The binder that can be included in the negative electrode material layer is not particularly limited, but is at least one selected from the group consisting of styrene butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resin, and polyamideimide resin. Can be mentioned. In a more preferred embodiment, the binder contained in the negative electrode material layer is styrene butadiene rubber. The conductive aid that can be included in the negative electrode material layer is not particularly limited, but carbon black such as thermal black, furnace black, channel black, ketjen black, and acetylene black, graphite, carbon nanotube, and vapor phase growth. Examples thereof include at least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives. In addition, the component resulting from the thickener component (for example, carboxymethylcellulose) used at the time of battery manufacture may be contained in the negative electrode material layer.

In a more preferred embodiment, the negative electrode active material and the binder in the negative electrode material layer are a combination of artificial graphite and styrene butadiene rubber.

The positive electrode current collector and the negative electrode current collector used for the positive electrode and the negative electrode are members that contribute to collecting and supplying electrons generated in the active material due to the battery reaction. Such a current collector may be a sheet-like metal member and may have a porous or perforated form. For example, the current collector may be a metal foil, a punching metal, a net or an expanded metal. The positive electrode current collector used for the positive electrode is preferably made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel, nickel and the like, and may be, for example, an aluminum foil. On the other hand, the negative electrode current collector used for the negative electrode is preferably made of a metal foil containing at least one selected from the group consisting of copper, stainless steel, nickel and the like, and may be, for example, a copper foil.

The separator 3 is a member provided from the viewpoints of preventing a short circuit due to contact between the positive and negative electrodes and holding the electrolyte. In other words, the separator can be said to be a member that allows ions to pass while preventing electronic contact between the positive electrode and the negative electrode. Preferably, the separator is a porous or microporous insulating member and has a film form due to its small thickness. Although only illustrative, a polyolefin microporous film may be used as the separator. In this regard, the microporous membrane used as the separator may include, for example, only polyethylene (PE) or only polypropylene (PP) as the polyolefin. Furthermore, the separator may be a laminate composed of “a microporous membrane made of PE” and “a microporous membrane made of PP”. The surface of the separator may be covered with an inorganic particle coat layer and / or an adhesive layer. The surface of the separator may have adhesiveness.

Electrolyte helps the movement of metal ions released from the electrodes (positive and negative electrodes). The electrolyte may be a “non-aqueous” electrolyte, such as an organic electrolyte and an organic solvent, or may be a “aqueous” electrolyte containing water. The secondary battery of the present invention is preferably a non-aqueous electrolyte secondary battery in which an electrolyte containing a “non-aqueous” solvent and a solute is used as an electrolyte. The electrolyte may have a form such as liquid or gel (in the present specification, “liquid” non-aqueous electrolyte is also referred to as “non-aqueous electrolyte solution”).

As a specific non-aqueous electrolyte solvent, a solvent containing at least carbonate is preferable. Such carbonates may be cyclic carbonates and / or chain carbonates. Although not particularly limited, examples of the cyclic carbonates include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), and vinylene carbonate (VC). be able to. Examples of the chain carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dipropyl carbonate (DPC). In one preferred embodiment of the present invention, a combination of cyclic carbonates and chain carbonates is used as the non-aqueous electrolyte, for example, a mixture of ethylene carbonate and diethyl carbonate.
As specific nonaqueous electrolyte solutes, for example, Li salts such as LiPF ₆ and LiBF ₄ are preferably used.

As the current collecting lead, any current collecting lead used in the field of secondary batteries can be used. Such a current collecting lead may be made of a material capable of achieving electron movement, and is usually made of a conductive material such as aluminum, nickel, iron, copper, and stainless steel. The form of the current collecting lead is not particularly limited, and may be, for example, a linear shape or a plate shape.

As the external terminal 5, any external terminal used in the field of secondary batteries can be used. Such an external terminal may be made of a material capable of achieving electron movement, and is usually made of a conductive material such as aluminum, nickel, iron, copper, and stainless steel. The form of the external terminal 5 is not particularly limited, and is usually plate-shaped. The external terminal 5 may be electrically and directly connected to the substrate 60, or may be electrically and indirectly connected to the substrate 60 through another device. The current collecting lead can also be used as an external terminal.

[substrate]
The substrate 60 may be a so-called rigid substrate or a flexible substrate. A rigid substrate is preferred. This is because when a rigid substrate is used, formation of a dead space and damage to the secondary battery due to the substrate are likely to be a problem, and even when a rigid substrate is used in the present invention, such a problem can be sufficiently avoided. . As the rigid substrate, any rigid substrate used in the field of substrates used with secondary batteries can be used, and examples thereof include a glass / epoxy resin substrate.

Examples of the substrate include an electronic circuit substrate such as a printed circuit board, a semiconductor substrate such as a silicon wafer, and a glass substrate such as a display panel.

When the board is a so-called protection circuit board for preventing overcharge, overdischarge and overcurrent of the secondary battery, a secondary battery pack is constituted by the protection circuit board and the secondary battery.

The secondary battery according to the present invention can be used in various fields where power storage is assumed. The secondary battery according to the present invention, particularly the non-aqueous electrolyte secondary battery, is merely an example, and the electric / information / communication field (for example, a mobile phone, a smart phone, a smart watch, a laptop computer) in which a mobile device is used. , Digital cameras, activity meters, arm computers, electronic paper, and other mobile devices), home / small industrial applications (eg, power tools, golf carts, home / nursing / industrial robots), large industrial applications (For example, forklifts, elevators, bay harbor cranes), transportation systems (for example, hybrid vehicles, electric cars, buses, trains, electric assist bicycles, electric motorcycles, etc.), power system applications (for example, various power generation, Fields such as road conditioners, smart grids, and general home storage systems , As well as, it is possible to use IoT field, space and deep sea applications (for example, spacecraft, areas such as submersible research vessel) and the like.

1: Positive electrode 2: Negative electrode 3: Separator 5: External terminal 6: Exterior body 6a: Upper exterior member 6b: Lower exterior member 7: Boundary line between secondary battery (peripheral region) and notch 8: 8A: B : 8C: 8D: 8E: 8F: 8G: Notch 60: 60A: 60B: 60C: 60D: 60E: 60F: 60G: Substrate 70: Longest side 71a: 71b: 72a: 72b: 73a: 73b: 74a: 74b : 75a: 75b: 76a: 76b: 77a: 77b: Line segment connected to the longest side 90a to 90h: 91a to 91f: 92a to 92f: 93a to 93e: 94a to 94e: 95a to 95e: 96a to 96e: Peripheral portion 100: 100A: 100B: 100C: 100D: 100E: 100F: 100G: Secondary battery

Claims

An electrode assembly including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and a secondary battery in which an electrolyte is enclosed in an exterior body,
The secondary battery has a shape with a notch in plan view,
The said exterior body is a secondary battery comprised from the sheet | seat folded by the longest side in the outline of the planar view shape which the said secondary battery has.
The secondary battery according to claim 1, wherein the exterior body is composed of a single soft sheet.
The secondary battery according to claim 1 or 2, wherein the soft sheet is a plastic sheet.
The secondary battery according to any one of claims 1 to 3, wherein the outer package is a flexible pouch.
The secondary battery according to any one of claims 1 to 4, wherein the longest side has a linear shape.
The secondary battery according to any one of claims 1 to 5, wherein the secondary battery does not have a seal portion at a peripheral edge adjacent to the longest side among peripheral edges in a planar view shape of the secondary battery. battery.
The secondary battery according to any one of claims 1 to 6, wherein the secondary battery has a seal portion at a peripheral edge other than the peripheral edge adjacent to the longest side among the peripheral edges in a planar view shape of the secondary battery. Secondary battery.
8. The secondary battery according to claim 7, wherein a seal part at a peripheral edge adjacent to a line segment connected to the longest side among the seal parts can be bent in a thickness direction of the secondary battery. Secondary battery.
The secondary battery further includes two external terminals,
The secondary battery according to claim 7 or 8, wherein the two external terminals are provided so as to protrude from the seal portion.
The secondary battery according to claim 9, wherein the two external terminals are provided so as to protrude from a seal portion other than a seal portion at a peripheral edge adjacent to a line segment connected to the longest side among the seal portions. .
The two external terminals are provided so as to protrude from a seal portion at a peripheral edge adjacent to a boundary line between the secondary battery and the notch portion of the seal portion toward the notch portion. Item 11. The secondary battery according to Item 9 or 10.
The secondary battery according to any one of claims 9 to 11, wherein the two external terminals are electrically connected to a substrate disposed in the notch.
The secondary battery according to claim 12, wherein the substrate is a rigid substrate or a flexible substrate.
The secondary battery according to claim 12 or 13, wherein the substrate is a protective circuit substrate.
The secondary battery is arranged such that at least a part of the seal part at the peripheral edge adjacent to the boundary line between the secondary battery and the notch part overlaps the end part of the substrate. The secondary battery according to any one of claims 7 to 14.
The secondary battery according to claim 15, wherein a ratio of an overlapping area by the substrate in a seal portion at a peripheral edge adjacent to the boundary line is 50% or more.
The secondary battery according to any one of claims 1 to 16, wherein a boundary line between the secondary battery and the notch includes one or more straight lines, one or more curves, or a combination thereof.
The secondary battery before forming the notch has a rectangular shape,
The secondary battery according to any one of claims 1 to 17, wherein the cutout portion is arranged to share two sides with the secondary battery before the cutout portion is formed.
The electrode assembly has a planar stacked structure in which a plurality of electrode units including the positive electrode, the negative electrode, and the separator are stacked in a planar shape, or the electrode unit including the positive electrode, the negative electrode, and the separator is rolled. The secondary battery according to any one of claims 1 to 18, which has a wound structure.
The secondary battery according to any one of claims 1 to 19, wherein the positive electrode and the negative electrode have a layer capable of inserting and extracting lithium ions.
A device comprising: the secondary battery according to any one of claims 1 to 20; and a substrate disposed in the notch.
The substrate is a protective circuit substrate;
The device according to claim 21, wherein the device is a secondary battery pack.
The device according to claim 21 or 22, wherein the device is a mobile device.