JP2019091656A - Power storage element and power storage device - Google Patents

Abstract

To provide a power storage element and a power storage device, capable of improving energy density.SOLUTION: A power storage element 1 includes: an exterior body 2 in which an electrode body 7 is housed; and terminals 3, 4 having conduction parts 30, 40, each of which has a cross section of a long circular shape and is insert-molded to the exterior body 2 in a state penetrating through the exterior body 2, and first flat planes 3b, 4b, each of which is provided at one end of the conduction parts 30, 40 and to which a tab 72 and a tab 73 of the electrode body 7 are joined. Since a caulked portion of a conventional terminal and a current collector occupy a space in an internal space of the exterior body 2, the electrode body 7 can be enlarged and energy density is improved.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electricity storage element provided with a terminal provided to an exterior body in a state of penetrating the exterior body, and an electricity storage device provided with the electricity storage element.

  Storage devices such as lithium ion secondary batteries have been used as power supplies for mobile devices such as notebook computers and mobile phones. In recent years, the power supply of EV (electric vehicle), HEV (hybrid electric vehicle), PHEV (plug-in hybrid electric vehicle), etc. is used in a wide range of fields.

  In general, in an electricity storage element, an electrode body formed by laminating or winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween is airtightly housed in an outer package together with an electrolytic solution. The positive electrode terminal and the negative electrode terminal electrically connected to the electrode body are provided on a cover plate or the like of the exterior body.

  Among storage elements, there is known one in which an electrode terminal and a current collector are electrically connected by allowing a terminal to pass through an outer package and an insulator and be crimped to the current collector (for example, Patent Document 1) reference). In this case, the insulator is pressed by the fastening force by caulking, and a certain airtightness is secured.

JP, 2014-72190, A

  When the electrode terminal is crimped in the container, the crimped portion partially occupies the internal space of the container, so the electrode body needs to be made smaller accordingly. In order to improve the energy density of the storage element, a configuration capable of maximizing the size of the electrode body in the container is required.

  An object of the present invention is to provide a storage element and a storage device capable of improving energy density.

  The storage element according to the present invention is provided with an exterior body for housing an electrode body, a conductive portion having an oval cross section and inserted into the exterior body in a state of penetrating the exterior body, and provided at one end of the conductive portion And a terminal having a first flat surface to which the tab of the electrode body is joined.

  A storage device according to the present invention includes the plurality of storage devices described above and a bus bar connecting the adjacent storage devices, and the terminal of each storage device has a second plane at the other end of the conductive portion. The bus bar is joined to the second plane.

  According to the storage element of the present invention, the terminal is integrated with the outer package by insert molding, and the tab is directly joined to the first plane of the conductive portion. Compared to the structure in which one end of the conductive portion is crimped to the current collector, the structure of the terminal is simplified, the terminal can be easily formed, and the terminal can be easily integrated into the outer package. Since the crimped portion of the conventional terminal and the current collector occupy the space in the internal space of the exterior body, the electrode body can be enlarged, and the energy density is improved. The terminal has a wide bonding surface (first plane) at one end of the conductive portion having an oval cross section, and the bonding property of the tab of the electrode body is good.

  According to the power storage device of the present invention, in the terminal, a wide bonding surface (second plane) for bonding the bus bar to the other end of the conductive portion having an oval cross section can be secured, and the bonding property between the terminal and the bus bar is good. It is.

It is a perspective view of the electrical storage element which concerns on 1st embodiment. It is a top view of an electrical storage element. It is a back view of the cover plate of an electrical storage element. It is the IV-IV sectional view taken on the line of FIG. It is an expanded sectional view of FIG. It is a top view showing an electricity storage device which has a plurality of electricity storage elements. It is a perspective view of the electrical storage element which concerns on 2nd embodiment. It is an expanded sectional view of the attachment part of a negative electrode terminal.

(Outline of this embodiment)
The storage element of the present embodiment is provided with an exterior body for accommodating an electrode body, a conductive portion having an oval cross section and insert-molded in the exterior body in a state of penetrating the exterior body, and provided at one end of the conductive portion And a terminal having a first flat surface to which the tab of the electrode body is joined.

Here, an oval means a shape having no corner, and a shape whose outer periphery is a curve (ellipse) made of a set of points such that the sum of distances from two fixed points on a plane is constant. The shape may be such that the ends of a pair of substantially parallel long sides are connected by a semicircle.
According to the above configuration, the terminal is integrated with the outer package by insert molding, and the tab is directly joined to the first flat surface of the terminal. The structure of the terminal itself and the connection structure of the terminal are simplified as compared with the structure in which one end of the conductive portion is crimped to the current collector. Since the terminal has an oval shape in cross section, the insert moldability is good, and the terminal can be easily integrated into the outer package. With the conductive portion having a cross-sectional shape having no corners, the sealability around the terminals by the insert resin is maintained for a long time. The conductive portion may have an oval shape in cross section only at a portion where the insert resin contacts. It is preferable that the conductive portion has an oval shape in cross section from one end to the other end so that the conductive portion can be easily formed by a punching process described later.
Since the crimped portion of the conventional terminal and the current collector occupy the space in the internal space of the exterior body, the electrode body can be enlarged, and the energy density is improved. The terminal can secure a wide bonding surface at one end (first plane) of the conductive portion having an oval cross section, and the bonding property of the tab of the electrode body is good.
Since the tab is connected directly under the conductive portion, the current path from the tab to the terminal is short. Since the current path is short and the junction between the first plane and the tab is wide, the resistance loss of the current path can be reduced. Therefore, in the storage element, even if a large current flows, it is difficult to melt the current path.

  The terminal includes copper, and a coating may be formed on a portion of the surface of the terminal including the copper in contact with the insert resin, or the portion may be roughened by chemical etching.

  Copper does not have good bondability with the insert resin. According to the above configuration, the film on the surface of the terminal including copper is in contact with the insert resin, or the surface is roughened, so that the bonding between copper and the insert resin is improved, and electrolysis is performed. The liquid is prevented from leaking along the conductive portion and corrosion resistance is good.

  The terminal may be formed of a clad material of copper and aluminum.

  According to the above configuration, when the terminals of the plurality of storage elements are connected by the bus bar and the bus bar is made of aluminum, the weldability between the aluminum portion of the terminal and the bus bar is good and the connection between the terminal and the bus bar is good It is. Laser welding is possible as a welding method.

  A film may be formed on a portion of the surface of the portion formed of copper of the terminal in contact with the insert resin.

  According to the above configuration, a film is formed on a portion of the surface of the terminal containing copper in contact with the insert resin, so the bonding property between the copper and the insert resin is improved, and the electrolytic solution creeps up along the conductive portion. Leakage is prevented and corrosion resistance is good.

  The power storage device of the present embodiment includes the plurality of power storage elements described in any of the above and a bus bar connecting the adjacent power storage elements, and the terminal of each power storage element is connected to the other end of the conductive portion. The bus bar is joined to the second plane.

  According to the above configuration, a wide bonding surface (second plane) for bonding the bus bar to the other end of the conductive portion having an oval cross section can be secured, and the bonding property between the terminal and the bus bar is good.

First Embodiment
Hereinafter, the present invention will be described based on the drawings showing a storage element according to an embodiment. 1 is a perspective view of the storage element 1 according to the first embodiment, FIG. 2 is a plan view of the storage element 1, FIG. 3 is a back view of a lid 22 of the storage element 1, and FIG. 4 is a IV-IV line of FIG. FIG. 5 is an enlarged sectional view of FIG. Hereinafter, although the case where the storage element 1 is a lithium ion secondary battery will be described, the storage element 1 is not limited to a lithium ion secondary battery. FIGS. 1, 2, 4, and 5 also show a bus bar 8 used to connect a plurality of storage elements 1 in series to configure a storage device 10 described later.

  As shown in FIG. 1, the storage element 1 includes a case 2 having a case main body 21 and a cover plate 22, a negative electrode terminal 3, a positive electrode terminal 4, and support portions 5 and 6.

The case 2 is made of, for example, a metal such as aluminum, an aluminum alloy, stainless steel, or a synthetic resin. The case 2 has a rectangular parallelepiped shape, and accommodates an electrode body 7 and an electrolytic solution (not shown) described later. In the present embodiment, the cover plate 22 is disposed to face upward in FIG. 1 with respect to the installation surface (not shown) of the storage element 1. However, the lid plate 22 may be disposed to face laterally in FIG. .
The cover plate 22 has through holes 22a and 22b at both ends as shown in FIG.

  As shown in FIGS. 4 and 5, the negative electrode terminal 3 has a columnar shape whose cross section is oval. The negative electrode terminal 3 has a columnar conductive portion 30 penetrating the through hole 22a, an oval second plane (upper surface in FIG. 4) 3a, and an oval first plane (lower surface in FIG. 4) 3b. The second plane 3 a and the first plane 3 b are parallel to the lid plate 22.

The negative electrode terminal 3 is formed of copper, and a film 31 is formed on the side surface of the conductive portion 30 using a compound such as triazine thiol. The compound should just improve the bondability of copper and insert resin, and can prevent the leak which electrolyte solution creeps up along the electroconductive part 30. FIG. The film 31 can be omitted if the bonding property between the copper and the insert resin is good. In addition, instead of forming the film 31 on the side surface, the side surface may be roughened by chemical etching.
The negative electrode terminal 3 is insert-molded on the cover plate 22 in a state where the conductive portion 30 penetrates the through hole 22 a. That is, the negative electrode terminal 3 is provided on the cover plate 22 in a state of being supported by the support portion 5 formed of the insert resin.

The support portion 5 has a surrounding portion 51, a first contact portion 52, and a second contact portion 53. The surrounding portion 51 surrounds the side surface of the conductive portion 30. The first contact portion 52 is provided on the outer periphery of the surrounding portion 51, has a rectangular peripheral portion, and contacts the outer surface of the lid plate 22. The connecting portion 52a between the surrounding portion 51 and the first contact portion 52 is tapered. The second contact portion 53 is provided on the outer periphery of the surrounding portion 51, has a rectangular peripheral portion, and contacts the inner surface of the lid plate 22.
The shape of the peripheral portion of the first contact portion 52 and the second contact portion 53 is not limited to the rectangular shape, and may be another polygon or a circle.

As shown in FIG. 4, the positive electrode terminal 4 has a columnar shape whose cross section is oval. The positive electrode terminal 4 has a columnar conductive portion 40 penetrating the through hole 22b, an oval second flat surface 4a, and an oval first flat surface 4b. Unlike the negative electrode terminal 3, the positive electrode terminal 4 is made of aluminum and has a good bonding property with the insert resin, so no coating is formed on the side surface of the conductive portion 40.
The positive electrode terminal 4 is insert-molded on the cover plate 22 in a state where the conductive portion 40 penetrates the through hole 22 b. That is, the positive electrode terminal 4 is provided on the cover plate 22 in a state of being supported by the support portion 6 formed of the insert resin.

The support portion 6 has a surrounding portion 61, a first contact portion 62, and a second contact portion 63. The surrounding portion 61 surrounds the side surface of the conductive portion 40. The first contact portion 62 is provided on the outer periphery of the surrounding portion 61, has a rectangular peripheral edge, and contacts the outer surface of the lid plate 22. The connecting portion 62 a between the surrounding portion 61 and the first contact portion 62 has a tapered shape. The second contact portion 63 is provided on the outer periphery of the surrounding portion 61, has a rectangular peripheral portion, and contacts the inner surface of the lid plate 22.
The shape of the peripheral portion of the first contact portion 62 and the second contact portion 63 is not limited to the rectangular shape, and may be another polygon or a circle.

As shown in FIG. 4, in the electrode body 7, a plurality of positive electrode plates and negative electrode plates are alternately stacked via a separator to form a rectangular parallelepiped main body 71, and a negative electrode extending from the main body 71 toward the lid plate 22 It has a tab 72 and a positive electrode tab 73.
The electrode body 7 may be obtained by laminating a positive electrode plate and a negative electrode plate with a separator interposed therebetween and winding it in a flat shape.

The positive electrode plate is obtained by forming a positive electrode active material layer on both sides of a positive electrode substrate foil which is a plate-like (sheet-like) or long strip-like metal foil made of aluminum, an aluminum alloy or the like. The negative electrode plate is obtained by forming a negative electrode active material layer on both sides of a negative electrode substrate foil that is a plate-like (sheet-like) or long strip-like metal foil made of copper, copper alloy or the like.
As the positive electrode active material used in the positive electrode active material layer or the negative electrode active material used in the negative electrode active material layer, known materials can be used appropriately as long as the positive electrode active material or the negative electrode active material can occlude and release lithium ions. .

Examples of positive electrode active materials include polyanion compounds such as LiMPO ₄ , LiM ₂ SiO ₄ , LiMBO ₃ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), titanium Use of lithium transition metal oxides such as lithium oxide, spinel compounds such as lithium manganate, LiMO ₂ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.) Can.

As the negative electrode active material, for example, lithium metal, lithium alloy (lithium-aluminum, lithium-silicon, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium such as wood alloy, etc.) Other than these, alloys capable of storing and releasing lithium, carbon materials (eg, graphite, non-graphitizable carbon, graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), metal oxides, lithium metal oxides (Li ₄₎ Ti ₅ O ₁₂ etc.), polyphosphoric acid compounds etc. may be mentioned.

  The separator is formed of a sheet-like or film-like material to which the electrolytic solution infiltrates. Examples of the material for forming the separator include woven fabric, non-woven fabric, and porous and sheet-like to film-like resin. The separator separates the positive electrode plate and the negative electrode plate, and holds the electrolytic solution between the positive electrode plate and the negative electrode plate.

  The copper or copper alloy negative electrode tab 72 is joined to the first flat surface 3 b of the copper negative electrode terminal 3 by ultrasonic welding. The positive electrode tab 73 made of aluminum or aluminum alloy is joined to the first flat surface 4b of the positive electrode terminal 4 made of aluminum by ultrasonic welding. The method of joining the negative electrode tab 72 and the first flat surface 3b and the method of joining the positive electrode tab 73 and the first flat surface 4b are not limited to ultrasonic welding, and may be laser welding or resistance welding.

Hereinafter, a method of manufacturing the storage element 1 will be described.
First, the negative electrode terminal 3 and the positive electrode terminal 4 are formed by punching (trimming or punching).
A film 31 is formed on the surface of the side surface of the conductive portion 30 of the negative electrode terminal 3.
The negative electrode terminal 3 is disposed in the mold in a state where the negative electrode terminal 3 penetrates the through hole 22 a of the lid plate 22. The mold used here is configured such that the synthetic resin flows in the shape of the support portion 5. As a synthetic resin, PPS (polyphenylene sulfide resin) which added glass fiber, PP (polypropylene resin), etc. are mentioned, for example.
The support 5 is formed by injection molding a synthetic resin with this mold, and the negative electrode terminal 3 is supported by the lid plate 22.
The positive electrode terminal 4 is also insert-molded on the cover plate 22 simultaneously with the negative electrode terminal 3.
The negative electrode tab 72 is joined to the first flat surface 3 b of the negative electrode terminal 3 by ultrasonic welding, and the positive electrode tab 73 is joined to the first flat surface 4 b of the positive electrode terminal 4 by ultrasonic welding.
With the electrode body 7 housed in the case body 21, the lid plate 22 is joined to the peripheral edge of the opening of the case body 21 by laser welding.
An electrolytic solution is injected from a liquid injection hole (not shown) provided in the lid plate 22 and the liquid injection hole is closed by a plug, whereby the storage element 1 is obtained.

  FIGS. 1, 2, 4, and 5 show a state in which the bus bar 8 is joined to the second flat surface 3 a of the negative electrode terminal 3 by resistance welding. The second flat surface 3 a is oval, can secure a wide bonding surface for bonding the bus bar 8, and has a good bonding property between the bus bar 8 and the negative electrode terminal 3. The method of joining the bus bar 8 and the second flat surface 3a is not limited to resistance welding, and may be laser welding or ultrasonic welding.

FIG. 6 is a plan view showing a power storage device 10 having a plurality of power storage elements 1.
The storage device 10 is configured such that the storage element 1 is disposed so that the disposition of the negative electrode terminal 3 and the positive electrode terminal 4 in the front-rear direction (vertical direction in FIG. 6) is alternately reversed. Instead of the case 11, the holding member may hold the plurality of storage elements 1.
The negative electrode terminal 3 and the positive electrode terminal 4 of the adjacent storage elements 1 are connected by the bus bar 8, and the plurality of storage elements 1 are electrically connected in series. Similar to the negative electrode terminal 3, the bus bar 8 is joined to the second flat surface 4 a of the positive electrode terminal 4 by resistance welding. The method of joining the bus bar 8 and the second flat surface 4a is not limited to resistance welding, and may be laser welding.
Although FIG. 6 illustrates the case where the storage element 1 is arranged so that the negative electrode terminal 3 and the positive electrode terminal 4 face upward, the present invention is not limited to this. The negative electrode terminal 3 and the positive electrode terminal 4 are sideways The storage elements 1 may be arranged to face each other.

According to the present embodiment, since the negative electrode terminal 3 and the positive electrode terminal 4 are pillars in which the second flat surfaces 3a and 4a and the first flat surfaces 3b and 4b are oblong, the shape is simple and can be easily formed by punching. It is formed.
Unlike the structure in which the cover plate is penetrated and the conductive portion of the terminal is intervened by two insulators and caulked to the current collector in the case main body, the negative electrode terminal 3 and the positive electrode terminal 4 are covered by insert molding It is integrated into the plate 22. Since the negative electrode terminal 3 and the positive electrode terminal 4 have an oval shape in cross section, the insert moldability is good. The connection structure of the negative electrode terminal 3 and the positive electrode terminal 4 is simplified, so that the negative electrode terminal 3 and the positive electrode terminal 4 can be easily integrated with the lid plate 22 easily.

  Since the caulking part conventionally occupies in the internal space of the case main body, the electrode body 7 can be enlarged, and the energy density is improved. The negative electrode terminal 3 has a wide bonding surface (first flat surface 3b) at one end of the conductive portion 30 having an oval cross section, and the bonding property between the negative electrode terminal 3 and the negative electrode tab 72 is good. The bondability between the positive electrode terminal 4 and the positive electrode tab 73 is also good.

  Since the negative electrode tab 72 is connected directly below the conductive portion 30, the current path from the negative electrode tab 72 to the negative electrode terminal 3 is short. Since the current path is short and the joint surface between the first flat surface 3b and the negative electrode tab 72 is wide, the resistance loss of the current path can be reduced. Also in the positive electrode terminal 4, the resistance loss of the current path can be similarly reduced. Therefore, in the storage element 1, even if a large current flows, it is difficult to melt the current path.

  In the power storage device 10 of the present embodiment, a wide bonding surface (second flat surfaces 3a and 4a) for bonding the bus bar 8 to the other end of the conductive portion 30 having an oval cross section and the other end of the conductive portion 40 can be secured. 3. The bondability between the positive electrode terminal 4 and the bus bar 8 is good.

Second Embodiment
FIG. 7 is a perspective view of the storage element 13 according to the second embodiment, and FIG. 8 is an enlarged cross-sectional view of a portion where the negative electrode terminal 9 is attached. In FIG. 7 and FIG. 8, the same parts as in FIG. 1, FIG. 4 and FIG.
As shown in FIG. 7, the storage element 13 includes a case 2 having a case body 21 and a cover plate 22, a negative electrode terminal 9, a positive electrode terminal 4, and support portions 5 and 6.

  As shown in FIG. 8, the negative electrode terminal 9 is in the form of a column having an oval cross section, and is made of a clad material in which dissimilar metals are bonded. The negative electrode terminal 9 is formed of copper and has a columnar shape, and the first conductive portion 91 through which the through hole 22 a is inserted, and the second conductive portion 92 formed of aluminum and having a columnar shape and joined to the first conductive portion 91. , A second plane 9a, and a first plane 9b. As an example of thickness, the case where the thickness of the 1st conductive part 91 is 3 mm and the thickness of the 2nd conductive part 92 is 3 mm is mentioned.

  A film 93 is formed on the side surface of the first conductive portion 91 using a compound such as triazine thiol. The compound should just improve the bondability of copper and insert resin, and can prevent the leak which electrolyte solution creeps along the 1st conductive part 91. As shown in FIG. The coating 93 can be omitted if the bonding between the copper and the insert resin is good.

Similar to the negative electrode terminal 3 of the first embodiment, the negative electrode terminal 9 is integrated with the cover plate 22 in a state of being supported by the support portion 5 formed of the insert resin.
The positive electrode terminal 4 has a configuration similar to that of the positive electrode terminal 4 of the first embodiment, and is integrated with the lid plate 22 in a state of being supported by the support portion 6 formed of the insert resin.

One end of a bus bar 14 made of aluminum is joined to the second plane 9 a of the end of the second conductive portion 92 made of aluminum of the negative electrode terminal 9 by laser welding. Since all of them are made of aluminum, the bondability between the second conductive portion 92 and the bus bar 14 is good.
One end of a bus bar 14 made of aluminum is joined to the second flat surface 4a of the end of the conductive portion 40 of the positive electrode terminal 4 made of aluminum by laser welding (not shown). Since all of them are made of aluminum, the bondability between the conductive portion 40 and the bus bar 14 is good.
Since the bonding property between the negative electrode terminal 3 and the positive electrode terminal 4 and the bus bar 14 is good, the plurality of storage elements 1 can be connected favorably to constitute a storage device.
The welding method is not limited to laser welding, and resistance welding may be used.

The present invention is not limited to the contents of the embodiments described above, and various modifications can be made within the scope of the claims. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.
Although the case where the storage element 1 is a lithium ion secondary battery is described in the first embodiment and the second embodiment, the storage element 1 is not limited to a lithium ion secondary battery. The storage element 1 may be another secondary battery such as a nickel hydrogen battery, a primary battery, or an electrochemical cell such as a capacitor. Also, the present invention is not limited to the case where the negative electrode terminal 3 or the positive electrode terminal 4 is provided on the cover plate 22, and the negative electrode terminal 3 or the positive electrode terminal 4 may be provided on the side plate of the case 2.

1, 13 storage element 2 case 21 case main body 22 cover plate 3, 9 negative electrode terminal 30, 40 conductive portion 31, 93 coating 91 first conductive portion 92 second conductive portion 3 a, 4 a, 9 a second flat surface 3 b, 4 b, 9 b First plane 4 positive electrode terminal 5 support portion 51, 61 surrounding portion 52, 62 first contact portion 53, 63 second contact portion 6 support portion 7 electrode body 71 main body 72 negative electrode tab 73 positive electrode tab 8, 14 bus bar 10 storage apparatus

Claims (5)

An exterior body for housing the electrode body,
A terminal having a conductive portion which has an oval cross section and is insert-molded in the outer package in a state of penetrating the outer package, and a first flat surface provided at one end of the conductive section and to which a tab of the electrode assembly is joined And a storage element. The terminal comprises copper and
The storage element according to claim 1, wherein a coating is formed on a portion of the surface of the terminal including the copper in contact with the insert resin, or the portion is roughened by chemical etching.   The storage element according to claim 1, wherein the terminal is formed of a clad material of copper and aluminum.   The storage element according to claim 3, wherein a film is formed on a portion of the surface of the portion formed of copper of the terminal in contact with the insert resin. A plurality of storage elements according to any one of claims 1 to 4;
And a bus bar connecting adjacent ones of the storage elements;
The storage device, wherein the terminal of each storage element has a second flat surface at the other end of the conductive portion, and the bus bar is joined to the second flat surface.

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