JP7154875B2 - Storage element - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminate-type electric storage element in which a power generation element is housed in an exterior body made of a laminate film.

In recent years, extremely thin electronic devices (hereinafter also referred to as devices) with built-in power sources, such as IC cards equipped with a one-time password function and a display, or tags and tokens (one-time password generators), are becoming widespread. In order to realize these devices, it is essential to reduce the size and thickness of the power storage elements (primary batteries, secondary batteries, electric double layer capacitors, etc.) that serve as power sources. As a typical energy storage element suitable for miniaturization and thinning, there is a laminate type energy storage element described in Patent Document 1 below.

FIG. 1A shows the appearance of a laminate-type energy storage element (hereinafter also referred to as an energy storage element 101). Further, FIG. 1B shows an exploded perspective view of the basic structure of the storage element 101. As shown in FIG. As shown in FIG. 1A, the electric storage element 101 has a flat plate-like appearance, and the electrode body 2 is hermetically sealed in a flat bag-like exterior body 12 made of laminate films (13a, 13b). A positive electrode terminal plate 124 and a negative electrode terminal plate 128 (hereinafter collectively referred to as electrode terminal plates) are pulled out from one side (hereinafter also referred to as terminal edge 22) of the rectangular exterior body 12 so as to protrude outward. is

Next, the structure of the storage element 101 will be described with reference to FIG. 1B. In FIG. 1B, some members and parts are hatched so that they can be easily distinguished from other members and parts. As shown in FIG. 1B, the exterior body 12 is composed of two rectangular aluminum laminate films (13a, 13b) facing each other, and a peripheral region 21 indicated by hatching or a dotted frame in the figure is thermocompression bonded. It is formed into a bag-like shape by being welded by a method, and the inside is hermetically sealed. The laminate films (13a, 13b) are made by using a metal foil (FIG. 2A, reference numeral 32) such as aluminum foil or stainless steel foil as a base material, and one or more resin layers are laminated on the front and back sides of the base material 32. . In general, a protective layer (FIG. 2A, reference numeral 33) made of, for example, polyamide resin is provided on the front surface, which is the outer surface of the exterior body 12, and the back surface, which is the inner surface of the exterior body 12, is provided. For example, a heat-sealing layer (FIG. 2A, reference numeral 31) made of a heat-sealable resin such as polypropylene is provided.

The electrode body 2 is sealed inside the exterior body 12 together with an electrolytic solution (not shown). Here, when the direction in which the two laminate films (13a, 13b) face each other is defined as a vertical direction, and the surface with the vertical direction as a normal direction is defined as a horizontal plane, the electrode body 2 includes a sheet-shaped positive electrode 4 and a sheet-shaped positive electrode 4. and the negative electrode 8 are laminated in the vertical direction with the separator 6 interposed therebetween and are pressure-bonded. The positive electrode 4 is formed by disposing a positive electrode material 5 containing a positive electrode active material on one main surface of a positive electrode current collector 3 made of a metal plate or metal foil. The negative electrode 8 is formed by disposing a negative electrode material 9 containing a negative electrode active material on one main surface of a negative electrode current collector 7 made of a metal plate, metal foil, or the like. The positive electrode 4 and the negative electrode 8 are laminated such that the positive electrode material 5 and the negative electrode material 9 face each other with the separator 6 interposed therebetween. One ends of a strip-shaped positive electrode terminal plate 124 and a strip-shaped negative electrode terminal plate 128 are attached to the positive electrode current collector 3 and the negative electrode current collector 7, respectively. The other end sides of the positive electrode terminal plate 124 and the negative electrode terminal plate 128 protrude outward from the terminal edge 22 of the exterior body 12 so as to be parallel to the horizontal plane.

If the power storage element 101 is a lithium primary battery, the positive electrode 4 is obtained by coating the surface of the positive electrode current collector 3 with a slurry-like positive electrode material 5 containing a positive electrode active material such as manganese dioxide. The negative electrode 8 is obtained by press-bonding a foil-shaped or flat plate-shaped lithium metal or lithium alloy to the negative electrode current collector 7 . The following Non-Patent Document 1 describes the features, discharge performance, and the like of a thin manganese dioxide lithium primary battery, which is a laminate-type storage element that is actually sold as a product. In addition, in a power storage element provided as a product, as described in Patent Document 1, the peripheral edge region 21 on the side of the terminal edge 22 is sealed using a lead tab or strip-shaped tab film. Common.

JP 2018-10751 A

FDK Corporation, "Thin Lithium Primary Battery", [online], [searched on July 23, 2018], Internet <URL: http://www.fdk.co.jp/battery/lithium/lithium_thin.html>

When a conventional storage device is mounted on a circuit board, electrode terminals are soldered to printed wiring such as electrode pads formed on the circuit board. However, conventional storage devices are prone to a problem called "battery floating" when mounted. 2A and 2B are diagrams for explaining "battery floating". 2A is a diagram showing a state in which the storage element 101 is placed on the circuit board C prior to mounting, and FIG. 2B is a diagram showing a state in which the storage element 101 is mounted on the circuit board. be. Further, FIG. 2C shows a diagram for explaining a problem related to "battery floating". 2A, 2B, and 2C are vertical cross sections of the storage element 101 cut along a plane including the vertical direction and the front-back direction when the direction perpendicular to the terminal edge 22 is the front-back direction on a horizontal plane. It is a plan view.

First, "battery floating" will be explained. As shown in FIG. Then, a gap d is formed between the lower surface of the electrode terminal plates (124, 128) drawn out from the terminal edge 22 of the outer package 12 and the upper surface of the electrode pad P formed on the circuit board C. As shown in FIG. That is, the electrode terminals (124, 128) cannot be brought into surface contact with the electrode pads P only by placing the storage element 101 on the circuit board C. FIG. Therefore, when the tip side of the electrode terminal plate (124, 128) is pushed down to bring the electrode terminal (124, 128) into surface contact with the electrode pad P on the circuit board C, for example, as shown in FIG. 2B, In the exterior body 12, the lower edge 50 on the side of the terminal edge 22 in the thick region in which the electrode body 2 is accommodated serves as a fulcrum, and the opposite side of the terminal edge 22 of the storage element 101 floats, causing "battery floating." .

Here, when the exterior body 12 portion of the storage element 101 is pressed against the circuit board C in order to correct the floating state of the battery, the electrode terminals (124, 128) are pulled out from the terminal edge 22 as shown in FIG. 2C. In many cases, the terminal edge 22 of the lower laminate film 13b is used as a fulcrum to bend at the position of the base end where the lower laminate film 13b is formed. Then, when the base ends of the electrode terminal plates (124, 128) are bent, the substrate 32 of the laminate film 13b and the electrode terminals (124, 128) exposed at the terminal edges 22 of the outer package 12 are separated from each other by reference numeral 200 in the figure. , the electrode terminals (124, 128) and the substrate 32 of the laminate film 13b may be electrically connected.

Therefore, it is conceivable to seal the peripheral edge region 21 along the terminal edge 22 using the tab lead or strip-shaped tab film described in Patent Document 1 above. As is well known, a tab lead has a structure in which a part of a metal plate (hereinafter also referred to as a terminal lead) serving as electrode terminal plates (124, 128) is sandwiched between tab films made of a resin having heat-welding and insulating properties. have. Then, if the peripheral edge region 21 is thermally crimped with the terminal edge 22 side of the tab film of the tab lead or the band-like tab film protruding outside the outer package 12, the electrode terminal plates (124, 128) are laminated. Contact of the films (13a, 13b) with the substrate 32 can be suppressed.

However, tab leads are expensive components. In addition, in the case where a band-shaped tab film protrudes from the edge of the terminal for sealing, as described in Patent Document 1, the flexibility of the tab film causes the alignment accuracy between the two laminate films to deteriorate. There is also the problem of not being able to secure Of course, "battery float" also occurs in a storage element whose exterior body is sealed with a tab lead or strip-shaped tab film.

Therefore, the present invention provides a laminate-type electric storage device that can prevent the battery from floating when mounted on a circuit board and the conduction between the base material of the laminate film and the electrode terminal plate without increasing the manufacturing cost. The purpose is to provide an element.

In one aspect of the present invention for achieving the above object, an electrode body formed by stacking a flat positive electrode and a flat negative electrode is housed in a flat bag-shaped exterior body made of a laminate film, A storage element in which electrode terminal plates are connected to the positive electrode and the negative electrode, respectively,
The stacking direction of the positive electrode and the negative electrode is the vertical direction, and the plane with the vertical direction as the normal direction is the horizontal plane,
mounted on an external electronic circuit board having a mounting surface parallel to the horizontal surface and a mounting surface parallel to the horizontal surface and in contact with the lower surface of the exterior body ;
In the electrode terminal plate, a terminal portion is a region that is drawn out in a horizontal outward direction from a predetermined edge of the exterior body,
The terminal portion has a tip portion having a surface parallel to the horizontal surface, which is bent downward with a gap from a predetermined edge of the exterior body, and bent again in a horizontal outward direction. death,
The vertical position of the lower surface of the tip portion is adjusted so as to be the position of the mounting surface when the exterior body is placed on the mounting surface.
It is characterized by

It is also possible to use an electric storage element having only one of the positive electrode and the negative electrode. Further, the power storage element may include a negative electrode made of lithium metal or a lithium alloy, and an irregular-shaped electrolyte housed inside the exterior body.

According to the present invention, it is possible to prevent the battery from floating during mounting on the circuit board and the conduction between the base material of the laminate film and the electrode terminal plate while suppressing an increase in manufacturing cost. is provided.

It is a figure which shows the external appearance of a general lamination-type electrical storage element. FIG. 2 is an exploded perspective view showing the basic structure of the general laminate-type energy storage device. FIG. 4 is a diagram showing a state in which the general laminate-type energy storage device is placed on a circuit board; FIG. 4 is a diagram showing a state of battery floating that occurs when the general laminate type storage element is mounted on a circuit board. FIG. 4 is a diagram showing how electrical continuity occurs between the base material of the laminate film and the electrode terminal plate in the general electric storage device. 1 is a diagram showing the appearance of an electric storage device of the present invention; FIG. FIG. 4 is a diagram showing a state in which the storage device according to the example is mounted on a circuit board;

Embodiments of the invention are described below with reference to the accompanying drawings. In addition, in the following drawings used for explanation, the same reference numerals are given to the same or similar parts, and redundant explanation may be omitted. Also, depending on the drawing, unnecessary reference numerals may be omitted in the description.

=== Structural Problems of Conventional Electrode Terminal Plates ===
As described above, in the electric storage element 101, the battery may float when it is mounted on the substrate, and when the battery float is corrected, the base material 32 of the laminate film 13b and the electrode terminals (124, 128) are electrically connected. There are problems such as In addition, if a band-shaped tab film is used to seal the peripheral region 21 on the side of the terminal edge 22 in order to reduce the manufacturing cost and prevent conduction, the flexibility of the tab film can be used to form the outer package. However, there is a problem that the alignment accuracy between the laminated films cannot be ensured. In order to secure the alignment accuracy while using the tab film, it is conceivable to insert a thermosetting resin tab with little deformation in advance between the laminates. In the electric storage element, if an insulating sheet is interposed between laminate films, it becomes difficult to reduce the thickness of the electric storage element.

Therefore, the present inventor does not insulate between the base material 32 of the laminate film (13a, 13b) exposed to the outside at the terminal edge 22 of the outer package 12 and the electrode terminal plate (124, 128), It was thought that if the so-called battery floating could be prevented, it would be possible to fundamentally prevent the occurrence of conduction between the substrate 32 of the laminate films (13a, 13b) and the electrode terminal plates (124, 128). Based on this idea, the present inventor has made intensive studies on the optimum shape and structure of the electrode terminal plate, and arrived at the present invention.

=== Example ===
<Structure of power storage element>
The basic structure and configuration of the energy storage device according to the embodiment of the present invention are the same as those of the general laminated energy storage device 101 shown in FIGS. 1A and 1B. However, the energy storage element according to the embodiment of the present invention (hereinafter also referred to as energy storage element 1) differs from the general energy storage element 101 shown in FIGS. 1A and 1B in the shape of the electrode terminal plate. Schematically, the electrode terminal plate, which extends horizontally from the terminal edge 22 to the outside of the exterior body 12 with the plane normal to the vertical direction as a horizontal plane, is bent downward, The tip is further bent horizontally to form a crank shape.

FIG. 3 shows the external shape of the electric storage element 1 according to the example of the present invention. Further, FIG. 4 shows the electric storage device 1 mounted on the circuit board C. As shown in FIG. 3 is a perspective view of the storage element 1, and FIG. 4 is a longitudinal sectional view of the storage element 1. FIG. Hereinafter, assuming that the terminal edge 22 of the exterior body 12 is the front side, as shown in FIGS. (24, 28) is bent downward at a position with a predetermined gap (43, 83) between terminal edge 22 and then bent forward again. Then, in the electrode terminal plates (24, 28), portions extending rearward from the tips to the first bending points (hereinafter also referred to as tip portions (41, 81)) are parallel to the horizontal plane. In addition, in the electric storage element 1 according to the example, the electrode terminal plates (24, 28) are bent at an angle of 90° at each bending position. Of course, the downward bending angle of the electrode terminal plates (24, 28) protruding horizontally from the terminal edge 22 of the outer package 12 does not have to be 90 degrees. The downward bending angle is an obtuse angle so that the electrode terminal plates (24, 28) are further away from the terminal edges 22, which are the locations where electrical connection between the laminate films (13a, 13b) and the substrate 32 occurs. It is desirable to

Further, the tip portions (41, 81) are vertically positioned so as to be in surface contact with the electrode pads P on the circuit board. That is, only by placing the storage element 1 on the circuit board C, the lower surfaces of the tip portions (41, 81) of the electrode terminal plates (24, 28) come into surface contact with the upper surfaces of the electrode pads P on the circuit board C. . As a result, when the power storage element 1 is mounted on the circuit board C, floating does not occur. As a result, it becomes unnecessary to press the lower end surface of the storage element 1 against the upper end surface of the circuit board. In addition, in the electric storage device 1 according to the example, the electrode terminal plates (24, 28) are bent downward at a position apart from the terminal edge 22 of the exterior body 12, so that the electrode terminal plates (24, 28) and the laminate The base material 32 of the film 13b does not contact. That is, in the storage device 1, in principle, electrical continuity does not occur between the substrate 32 of the laminate film 13b and the electrode terminal plates (24, 28).

As a procedure for manufacturing the storage element 1, first, the conventional storage element 101 shown in FIG. 1A is manufactured, and then the electrode terminal plates (24, 28) are formed into a crank shape by well-known press working. Of course, crank-shaped electrode terminal plates ( 24 , 28 ) prepared in advance may be attached to the electrode body 2 .

=== Performance Evaluation ===
First, in order to evaluate the effect of preventing battery floating in the energy storage element 1 according to the embodiment of the present invention, the energy storage element 1 according to the embodiment shown in FIG. 3 and the conventional energy storage element 101 shown in FIG. An electric storage device corresponding to 1 was produced as a sample. Specifically, a thin manganese dioxide lithium primary battery described as CF042722U in the above non-patent document was used as a sample corresponding to the conventional storage element 101 (hereinafter also referred to as a sample of a comparative example), and the electrode terminal plate (24, 28), a thin manganese dioxide lithium primary battery having the same structure, configuration, and size as CF042722U except that the shape of 28) was changed to a crank shape was used as a sample corresponding to the storage element 1 according to the example (hereinafter also referred to as the sample of the example). ). Also, 30 individuals were prepared for each of the sample of the example and the sample of the comparative example. Then, all individual samples were mounted on a predetermined circuit board C, and the presence or absence of battery floating was examined. Regarding the presence or absence of battery float, when the edge opposite to the terminal edge 22 was floated from the upper surface of the circuit board C by 5 mm or more, it was determined as "battery float".

Table 1 below shows the state of occurrence of battery floating in each sample.

表１に示したように、比較例のサンプルにおいては、３０個の個体の全てにおいて電池浮きが発生し、実施例のサンプルにおいては、全ての個体において電池浮きが発生しなかった。

As shown in Table 1, battery floating occurred in all 30 individual samples of the comparative example, and battery floating did not occur in all the individual samples of the example.

Next, regarding the sample of the comparative example, the possibility of occurrence of conduction between the base material 32 of the laminate films (13a, 13b) and the electrode terminal plates (124, 128) when correcting the battery floating was examined. Here, 30 individual pieces were prepared separately from the individual pieces used for evaluating the battery floating, and the electrode terminal plates (124, 128) of each individual piece were bent downward by 90° at the position of the proximal end. . Then, the resistance value between the electrode terminal plates (124, 128) and the substrate 32 of the laminate film 13b was measured while the electrode terminal plates (124, 128) were bent. The resistance value was measured by applying a probe to the laminate film 13b and applying a DC voltage of 5.0 V between the laminate film 13b and the electrode terminal plates (124, 128). Regarding the presence or absence of electrical continuity between the substrate 32 of the laminate film (13a, 13b) and the electrode terminal plates (124, 128), the substrate 32 of the laminate film 13b and either the positive or negative electrode terminal plate (124, 128) If the resistance value between the two was 100 MΩ or less, it was determined that conduction had occurred. Then, as a result of measuring the resistance value of each individual, 28 of the 30 individuals showed continuity between the substrate 32 of the laminate films (13a, 13b) and the electrode terminal plates (124, 128). had occurred. That is, in the conventional electric storage device 101, when a battery float occurs during mounting, when the lower surface of the outer package 12 is brought into contact with the upper surface of the circuit board C in an attempt to correct the battery float, the electrode terminal plate ( 124, 128) are bent at the position of the terminal edge 22, there is a high possibility that electrical continuity will occur with the substrate 32 of the laminate films (13a, 13b).

As described above, the electric storage device 1 according to the embodiment can prevent the battery from floating when mounted on the circuit board. Moreover, as described above, in principle, no electrical connection occurs between the base material 32 of the laminate films (13a, 13b) and the electrode terminal plates (24, 28).

===Other Examples===
The description of the above embodiments is intended to facilitate understanding of the present invention, and does not limit the technical scope of the present invention. The present invention can be modified and improved without departing from the spirit of the above embodiments, and the present invention includes equivalents thereof.

In the energy storage device 1 according to the embodiment of the present invention, a flat positive electrode 4 and a flat negative electrode 8 are stacked vertically in a flat bag-shaped exterior body 12 made of laminated films (13a, 13b). The storage element 1 is not limited to a lithium primary battery as long as the storage element 1 accommodates a different electrode body 2 . Of course, the storage device 1 according to the embodiment may be a secondary battery or an electric double layer capacitor. A power storage element having a polymer electrolyte instead of the electrolytic solution may be used. Alternatively, it may be a battery such as an all-solid-state battery that does not include an electrolytic solution and a separator 6 .

The electrode body 2 is stacked vertically so that a plurality of sets of unit cells are connected in series, with a configuration in which one positive electrode 4 and one negative electrode 8 face each other via a separator 6 as one unit cell. may have been Then, the electrode body 2 composed of a plurality of series-connected unit cells may be housed in one exterior body 12 . However, the power supply for extremely thin electronic devices, such as IC cards, whose thickness is specified by the standard, usually has a "single-layer type" electrode, which is provided with one positive electrode 4 and one negative electrode 8, as in the above embodiment. is used. The floating battery becomes a bigger problem when it is incorporated into a thin electronic device. Therefore, when the present invention is applied to a single-layer laminate type electric storage device, a more remarkable effect can be obtained.

In the electric storage device 1 according to the above example, the electrode terminal plates (24, 28) were bent before being incorporated into the electronic device. However, when the storage device 1 is not intended for a specific electronic device but is incorporated into various electronic devices, the mounting state of the storage device 1 differs depending on the electronic device to be incorporated. In other words, the bent state of the electrode terminal plates (24, 28) differs depending on the electronic device in which it is incorporated. Therefore, the bent positions of the electrode terminal plates (24, 28) and the vertical positions of the tip portions (41, 81) may be adjusted immediately before the storage device 1 is shipped or assembled into an electronic device. As a result, the conventional power storage element 101 and the power storage element 1 according to the embodiment can be mixed and manufactured on the same production line, and the cost required for inventory control can be reduced.

In the electric storage device 1 according to the above embodiment, the thickness of the electrode pads P formed by the printed wiring is extremely thin. , the position of the upper surface of the circuit board C (hereinafter also referred to as the mounting surface). Of course, even if the mounting surface is arranged below or above the lower surface of the outer package 12, the electrode terminal plates (24, 28) are bent as appropriate so that the electrode terminal plate (24 , 28) should be aligned with the mounting surface.

1,101 power storage element, 2 electrode body, 3 positive electrode current collector, 4 positive electrode,
5 positive electrode material, 6 separator, 7 negative electrode current collector, 8 negative electrode, 9 negative electrode material, 12 exterior body, 13a, 13b laminate film, 21 peripheral region,
22 terminal edge, 24, 124 positive terminal plate, 28, 128 negative terminal plate,
31 heat seal layer of laminate film,
32 laminate film substrate (metal foil),
33 protective layer of laminate film, 41, 81 tip of electrode terminal plate,

Claims (3)

An electrode body in which a flat positive electrode and a flat negative electrode are laminated is housed in a flat bag-shaped exterior body made of a laminate film, and an electrode terminal plate is connected to each of the positive electrode and the negative electrode. A power storage element that is
The stacking direction of the positive electrode and the negative electrode is the vertical direction, and the plane with the vertical direction as the normal direction is the horizontal plane,
mounted on an external electronic circuit board having a mounting surface parallel to the horizontal surface and a mounting surface parallel to the horizontal surface and in contact with the lower surface of the exterior body ;
In the electrode terminal plate, a terminal portion is a region that is drawn out in a horizontal outward direction from a predetermined edge of the exterior body,
The terminal portion has a tip portion having a surface parallel to the horizontal surface, which is bent downward with a gap from a predetermined edge of the exterior body, and bent again in a horizontal outward direction. death,
The vertical position of the lower surface of the tip portion is adjusted so as to be the position of the mounting surface when the exterior body is placed on the mounting surface.
A power storage device characterized by: 2. The storage element according to claim 1, comprising only one of said positive electrode and said negative electrode. 3. The electric storage element according to claim 1, further comprising a negative electrode made of lithium metal or a lithium alloy, and an irregular-shaped electrolyte housed inside said exterior body.

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