JP2013077467A - Electrochemical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical device capable of improving connection reliability.SOLUTION: An electrochemical device includes: a power generation element 20 formed by laminating electrode plates 21 and 25 including active material formation parts 21A and 25A and foil exposure parts 21B and 25B; collectors 30 and 31 having body parts 30A and 31A extending from external terminals 13 and 14 provided on a casing 11 housing the power generation element 20 and a plurality of connection pieces 30B and 31B extended from the body parts 30A and 31A along laminated parts of the foil exposure parts 21B and 25B; and a clip 35, which is a component separate from the collectors 30 and 31, having a pair of clamping piece parts 35A for clamping at least the laminated part of the foil exposure parts 21B and 25B in the thickness direction thereof and an advancing piece part 35B for dividing the laminated part of the foil exposure parts 21B an 25B in the thickness direction thereof and clamping it with the clamping piece parts 35A, and welded to the connection pieces 30B and 31B together with the laminated part of the foil exposure parts 21B and 25B.

Description

  The present invention relates to an electrochemical device.

  Conventionally, an electrochemical device such as a battery or an electric double layer capacitor includes a power generation element in which an active material layer is formed on the surface of a metal foil. For example, as described in Patent Document 1 and Patent Document 2, the electrode plate constituting the power generation element is pressed by a roll press or the like after the active material layer is formed on the metal foil, and has a predetermined thickness. It has been adjusted. And an electric power generation element is obtained by winding in the state which pinched | interposed the separator between the pressed positive electrode plate and negative electrode plate.

  One end of the power generation element in the winding axis direction is provided with an uncoated portion where the active material layer is not formed in the metal foil constituting the positive electrode plate, and the other is the metal foil constituting the negative electrode plate A similar uncoated portion is provided in FIG. A positive electrode current collector is connected to an uncoated portion of the positive electrode plate, and a negative electrode current collector is connected to an uncoated portion of the negative electrode plate. A positive electrode or a negative electrode for inputting / outputting electric power to each current collector The external terminal is connected. The power generation element having such a configuration is manufactured as a battery by being housed in a battery container and filling an electrolyte between the electrodes of the power generation element.

  By the way, the positive electrode current collector and the negative electrode current collector described in Patent Literature 1 and Patent Literature 2 are corrugated plate-like clip portions welded to uncoated portions of the corresponding electrode plates, and substantially in the center of the clip portions. It is comprised from the flat connection piece part located and connected to an external terminal.

JP 2000-223109 A Japanese Patent Laid-Open No. 11-354095

  However, according to such a structure, since the connection piece part connected to an external terminal is not directly welded to the uncoated part of metal foil, there is a concern that the connection reliability is lowered. That is, in Patent Document 1, the connection piece portion further fixed to the external terminal fixed to the battery case and the clip portion welded to the uncoated portion of the electrode plate not fixed to the battery case. For example, even when the same external force is applied, the vibration mode is different, and as a result, stress concentrates on the boundary portion, and there is a possibility that connection reliability may be reduced due to breakage or the like.

  Further, in Patent Document 2, the clip portion and the connection piece portion are welded to the uncoated portion and the external terminal, respectively, and in the current collector that requires high connection reliability with respect to the electrode plate and the external terminal, It is not preferable that there are many welds. Furthermore, in any of the patent documents, the corrugated clip portion is particularly a connecting piece, because a plurality of uncoated portions are sandwiched in the concave portion and pressed and welded from both sides toward the connecting piece portion. The uncoated part located on the outer peripheral side away from the part is strongly pulled toward the connecting piece part side. For this reason, apart from the current collector, there is a concern that the connection reliability may be lowered even if the electrode plate itself is damaged.

  The present invention has been completed based on the above-described circumstances, and an object thereof is to provide an electrochemical device capable of improving connection reliability.

  The present invention includes an active material forming portion in which an active material layer is formed on the surface of a conductive foil, and a foil exposed portion that is located at an edge of the conductive foil and exposes the conductive foil from the active material. A power generation element formed by laminating electrode plates, a casing for housing the power generation element, an external terminal provided in the casing, a main body portion connected to the external terminal, and a laminated portion of the foil exposed portion in the power generation element A plurality of connection pieces extending from the main body portion along the line, a pair of sandwiching piece portions for sandwiching at least a laminated portion of the foil exposed portion in the thickness direction, and the foil exposure And an entry piece portion that divides the laminated portion in the thickness direction and sandwiches the divided laminated portion between the sandwiched piece portion and the connecting piece. The welded together with the laminated portion of the exposed foil portion Characterized in place and a clip separate part from the collector.

  According to such a configuration, connection reliability can be improved. More specifically, first, the current collector connected to the external terminal and the clip that is welded together with the connecting piece while sandwiching the foil exposed portion of the power generation element are separate parts. Compared to the case of the integrated type, there is no risk of stress concentration at the boundary due to the external force acting, and the connection reliability from the external terminal to the power generation element can be improved.

  Subsequently, the connecting piece of the current collector of the present invention is extended along the laminated portion of the foil exposed portion, and the connecting piece and at least the laminated portion of the foil exposed portion sandwiched between the clips are welded at a time. Therefore, the connection reliability is high compared to the conventional case where, for example, the power generation element and current collector, the current collector and external terminal are welded multiple times from the external terminal to the power generation element. Become.

  In addition, the clip of the present invention has an entry piece portion that is inserted so as to divide the laminated portion of the foil exposed portion in the thickness direction, and the foil exposed portion is sandwiched and welded between the sandwiched piece portions. It is. Moreover, the connection piece of the collector connected to the external terminal is a separate part from the clip, and a plurality of connection pieces are provided along the laminated portion of the foil exposed portion. Therefore, compared with the case where the foil exposed portions of the power generation elements located on the same side toward at least one connection piece are gathered together and welded, the connection pieces that are the weld destinations of the foil exposed portion are dispersed in a plurality. In addition, since the clip itself has an entry piece portion that is sandwiched and sandwiched between the foil exposed portions to be laminated, the foil exposed portion is hardly pulled by the current collector and the clip. Therefore, it can suppress that stress is concentrated on the part by being pulled, and the electrode plate itself is damaged or the active material is peeled off. As a result, it is possible to improve the connection reliability between the power generation element and the current collector.

  The clip may be provided for each connection piece. With such a configuration, it is not necessary to provide a large number of entry pieces per clip, which is convenient for manufacturing. Moreover, compared with the case where one clip is welded across a plurality of connection pieces, the degree of freedom is high, and the load (for example, stress concentration) on the foil exposed portion of the power generation element can be reduced.

  Before the welding to the laminated portion of the foil exposed portion, the clip is formed by integrally forming the flat plate-shaped sandwiching piece portion and the entry piece portion having a V-shaped cross section from a metal plate. It is preferable that each of the V-shaped portions is compressed from both sides and is in close contact with each other in a state where the V-shaped portion is welded to the laminated portion of the exposed foil portion.

  According to such a configuration, since the clip and the foil exposed portion of the power generation element sandwiched between the clips are joined without gaps for each clip in the stacking direction of the foil exposed portion, for example, the foil exposed portion is Even a single clip, such as a clip holding piece part and an entry piece part, or an entry piece part and a holding piece part, can withstand vibration and the like as compared to a case where it is divided into a plurality of pieces and connected with a gap. A predetermined strength or more can be ensured.

  ADVANTAGE OF THE INVENTION According to this invention, the electrochemical apparatus which can improve connection reliability can be provided.

1 is an exploded perspective view of a nonaqueous electrolyte secondary battery according to an embodiment of the present invention. Partially enlarged plan view schematically showing a state immediately before the power generating element and the current collector connecting piece are clamped by the clip and welded. Enlarged plan view schematically showing after welding

<Embodiment>
An embodiment of the present invention will be described with reference to FIGS.
The electrochemical apparatus of this embodiment has illustrated the case where it applies to the nonaqueous electrolyte secondary battery 10 (henceforth only battery) mounted, for example in vehicles, such as an electric vehicle and a hybrid vehicle. As shown in FIG. 1, in the battery 10, a flat power generation element 20 is accommodated in a rectangular case 11 (corresponding to a casing), and the case 11 is filled with an electrolytic solution. Hereinafter, the vertical direction in FIG. 1 will be referred to as the vertical direction of the battery 10, and the front side and the back side of the paper will be described as the front side and the rear side, respectively.

  The case 11 is configured as an upwardly open type with an open upper end, and the upper end opening of the case is closed by a rectangular plate-like lid body 12 (not shown). A positive terminal 13 and a negative terminal 14 (corresponding to external terminals) connected to the corresponding current collectors 30 and 31 respectively project from the both sides in the longitudinal direction of the lid 12. The positive electrode terminal 13 and the negative electrode terminal 14 are fastened to the corresponding positive electrode current collector 30 or negative electrode current collector 31 via the lid body 12 and packing (not shown) arranged above and below (inside and outside the case). .

  Each of the current collectors 30 and 31 is a metal plate having a sufficient thickness so as to obtain a large current capacity. The positive electrode current collector 30 is, for example, an aluminum alloy plate, and the negative electrode current collector 31 is, for example, a copper plate. It is formed using an alloy plate. Each of the current collectors 30 and 31 includes a flat plate-like main body portion 30A and 31A arranged along the back surface of the lid body 12, and two each of the main body portions 30A and 31A branched downward from the edge of the main body portion 30A and 31A. Connection portions 30B and 31B (corresponding to connection pieces) are provided. The connection portions 30A and 31B extend downward along the uncoated portions 21B and 25B, which will be described later, and are disposed at positions where the corresponding uncoated portions 21B and 25B are sandwiched from both the front and rear sides.

  The connection portions 30B and 31B of the current collectors 30 and 31 are connected to the welding portions 22 and 26 (corresponding to the welding portions in the laminated portion of the foil exposed portions) of the power generation element 20 by the clip 35. The clip 35 is made of a material having a resistance value equivalent to the material of the current collectors 30 and 31 to be welded and the welded portions 22 and 26 of the power generation element 20. For example, the positive electrode side is made of an aluminum alloy and the negative electrode side is made of a copper alloy. Is desirable.

  The power generation element 20 is configured to be wound in a flat shape with a separator (not shown) sandwiched between a positive electrode plate 21 (corresponding to an electrode plate) and a negative electrode plate 25 (corresponding to an electrode plate). In the unrolled state, each has a strip shape in which the winding direction is the longitudinal direction. The positive electrode plate 21 is positioned on one end side in the width direction with the coating part 21A (corresponding to the active material forming part) in which the positive electrode active material is supported on the surface of the aluminum foil, and the positive electrode active material is not applied to the aluminum foil. Is provided with a strip-shaped uncoated part 21B (corresponding to a foil exposed part). On the other hand, the negative electrode plate 25 has a width direction opposite to the coated portion 25A (corresponding to the active material forming portion) in which the negative electrode active material is supported on the surface of the copper foil and the uncoated portion 21B of the positive electrode plate 21. And an uncoated portion 25B (corresponding to a foil exposed portion) located at one end portion. Similarly, the uncoated portion 25B has a strip shape in which the copper foil is exposed without applying the negative electrode active material.

  A positive electrode or negative electrode active material layer is formed on each coating portion 21A, 25A. This active material layer has a main component as an active material, and additionally contains a binder, a conductive aid and the like. And in the state shifted in the surface direction so that the uncoated portion 25B of the negative electrode plate 25 does not overlap the separator and the positive electrode plate 21 so that the uncoated portion 21B of the positive electrode plate 21 does not overlap the separator and the negative electrode plate 25. It is wound and the electric power generation element 20 as shown in FIG. 1 is obtained.

  That is, the positive electrode side of both ends of the power generation element 20 corresponds to a laminated portion of a foil exposed portion in which only the uncoated portion 21B of the positive electrode plate 21 is laminated and protruded, and the negative electrode side is similarly the negative electrode plate 25. Only the uncoated part 25B corresponds to the laminated part of the exposed foil part which is laminated and protruded. The stacked portions of the uncoated portions 21B and 25B protruding from both sides of the power generation element 20 are superposed in a state of being sandwiched by the clips 35 together with the connection portions 30B and 31B of the corresponding current collectors 30 and 31. Welded portions 22 and 26 to be sonic welded are provided.

  Now, a total of four clips 35 of this embodiment are used, one for each of the connecting portions 30B, 31B of the current collectors 30, 31 provided two for each electrode. As shown in FIG. 2, the clip 35 has an M-shaped cross section in a state before welding, and a pair of sandwiching piece portions 35 </ b> A sandwiching the welded portions 22 and 26 on both sides thereof, and the entry piece portion 35 </ b> B is The cross-sectional V-shape is located between the pair of sandwiching piece portions 35A so as to be sandwiched between the uncoated portions 21B and 25B which are stacked.

  After welding, as shown in FIG. 3, the cross section of the clip 35 has an E shape. That is, the V-shaped entry pieces 35B are compressed from both sides and are in close contact with each other before welding. And it connects without gap in the lamination direction in the state which especially welded part 22 and 26 of each uncoated part 21B and 25B laminated | stacked with each connection part 30B and 31B for every clip 35 in the compressed state.

The present embodiment is configured as described above, and the operation and effect will be described subsequently.
First, an active material layer is formed by applying or spraying a slurry made of the active material corresponding to the positive electrode or the negative electrode on the surface of the aluminum foil or copper foil constituting the electrode plates 21 and 25 and drying the slurry. Then, in the roll pressing step, each metal foil on which the active material layer is formed is pressed in the thickness direction to form the positive electrode plate 21 and the negative electrode plate 25. The electrode plates 21 and 25 that have finished the roll press process are wound with a separator (not shown) between them, and uncoated portions 21B and 25B of the electrode plates 21 and 25 are arranged at both ends as shown in FIG. It is arranged by laminating each part.

  Subsequently, the current collectors 30 and 31 are connected to the power generation element 20 thus manufactured. In order to connect the current collectors 30 and 31, first, the connection portions 30B and 31B of the current collectors 30 and 31 and the corresponding welded portions 22 and 26 of the uncoated portions 21B and 25B are sandwiched between clips 35. . Specifically, as shown in FIG. 2, first, each uncoated portion 21B, 25B in a laminated state is divided into two for each corresponding connecting portion 30B, 31B, and the clip 35 enters the intermediate portion. The one part 35B is made to enter. At this time, the connecting portions 30B and 31B are entered into the intermediate portion together with the corresponding uncoated portions 21B and 25B so as to be positioned on both front and rear sides of the power generation element 20.

  Then, the welded portions 22 and 26 of the uncoated portions 21B and 25B divided into two are sandwiched between the sandwiching piece portion 35A and the entry piece portion 35B. Subsequently, an anvil is sandwiched between adjacent clips 35, and both ends of the current collectors 30, 31 are sandwiched between horns and pressurized, and ultrasonic welding is performed by applying ultrasonic vibration (see FIG. 3). . At this time, each uncoated part 21B, 25B is divided into two parts for each connection part 30B, 31B, and divided into a total of eight parts and ultrasonically welded to the corresponding clip 35. Therefore, even in the welded portions 22 and 26 farthest from the respective portions 35A and 35B of the clip 35, for example, the conventional uncoated portions are bundled together to bundle the uncoated portions on one electrode side and connect the current collectors. Compared with the case where welding is performed on the part, it is possible to alleviate stress concentration due to pulling, which causes foil breakage and peeling of the active material.

  Finally, the connected power generation element 20 and current collectors 30 and 31 are accommodated in the case 11, and after injecting the electrolyte, the terminals 13 and 14 are projected to the outside by the lid body 12. The battery 10 is completed by closing the upper part.

  As described above, according to the present embodiment, connection reliability can be improved. More specifically, first, the current collectors 30 and 31 connected to the electrode terminals 13 and 14, the connection portions 30 </ b> B and 31 </ b> B of the current collectors 30 and 31, and the uncoated portions 21 </ b> B and 25 </ b> B of the power generation element 20 are sandwiched. Since the clip 35 to be welded is a separate part, there is a risk that stress is concentrated on the boundary portion due to the external force acting as compared with the conventional case where the current collector and the clip are integrated. In addition, the connection reliability from the electrode terminals 13 and 14 to the power generation element 20 can be improved.

  Subsequently, the connection portions 30B and 31B of the current collectors 30 and 31 of the present embodiment are extended at both front and rear ends along the laminated portion of the uncoated portions 21B and 25B. 31B and the laminated portion of the uncoated portions 21B and 25B are sandwiched between clips 35 and welded at a time, so that, for example, conventional power generation elements and current collectors, current collectors and external terminals, etc. Compared to the case where welding is performed a plurality of times from the terminal to the power generation element, the connection reliability is increased.

  In addition, the clip 35 of the present embodiment has an entry piece portion 35B into which the laminated portion of the uncoated portions 21B and 25B is divided so as to be divided in the thickness direction, and is not coated with the sandwiching piece portion 35A. It is the structure which clamps and welds the process parts 21B and 25B and the connection parts 30B and 31B of the collectors 30 and 31. FIG. Further, the connection portions 30B and 31B of the current collectors 30 and 31 connected to the electrode terminals 13 and 14 are separate parts from the clip 35, and a plurality of connection portions 30B and 31B are provided along the laminated portion of the uncoated portions 21B and 25B. ing.

  Therefore, compared with the case where the uncoated portions of the power generation elements located on the same side toward one connection portion are gathered and welded, the connection portion which is the welding destination of the uncoated portions 21B and 25B 30B and 31B are dispersed in pairs for each electrode, and the clip 35 itself has an uncoated portion 21B and 25B for laminating and sandwiching the uncoated portions 21B and 25B. Becomes difficult to be pulled by the current collectors 30 and 31 and the clip 35. Therefore, it can suppress that stress concentrates on the part by being pulled, and the electrode plates 21 and 25 themselves are damaged or the active material layer is peeled off. As a result, it is possible to improve connection reliability between the power generation element 20 and the current collectors 30 and 31.

  In addition, since the clip 35 is provided for each of the connection portions 30B and 31B of the current collectors 30 and 31, there is no need to provide a large number of entry pieces 35B per clip 35, which is convenient for manufacturing. Moreover, compared with the case where one clip is welded across a plurality of connection portions, the degree of freedom is high, and the load (for example, stress concentration) near the uncoated portions 21B and 25B of the power generation element 20 is also increased. It can be reduced.

  Further, the clip 35, the connection portions 30B and 31B of the current collectors 30 and 31 sandwiched therebetween, and the uncoated portions 21B and 25B of the power generation element 20 are clipped in the stacking direction of the uncoated portions 21B and 25B. For example, even if the uncoated part is a single clip such as a clip holding piece part and an entry piece part, an entry piece part and a holding piece part, etc. Compared to the case where the connection is divided into a plurality of portions with a gap, it is possible to ensure a predetermined strength or more that can withstand vibrations.

  Moreover, if the clip 35 illustrated in this embodiment is used, a horn is provided at both ends of the uncoated portions 21B and 25B of the electrode plates 21 and 25, and an anvil is provided between the sandwiching pieces 35A of the adjacent clips 35. By installing, ultrasonic welding can be performed, and the configuration of the present embodiment can be easily applied to the conventional configuration.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the above-described embodiment, one clip 35 is provided for each connection portion 30B, 31B of the current collectors 30, 31, but the present invention is not limited to this, and one clip is provided for a plurality of connection portions. Individual clips may be provided. For example, one clip may be arranged for each current collector.

  (2) In the above-described embodiment, the connection portions 30B and 31B of the current collectors 30 and 31 are sandwiched between the sandwiching piece portions 35A of the clip 35 together with the welded portions 22 and 26 of the uncoated portions 21B and 25B. However, the present invention is not limited to this. Only the uncoated part (the welded part) is sandwiched between clips, and the connection part is placed outside the clip, so that the uncoated part of the power generation element, the clip, and the current collector You may weld the connection part of a body at once.

  (3) In the above-described embodiment, the clip 35 is constituted by the pair of sandwiching piece portions 35A and the entry piece portion 35B positioned between the sandwiching piece portions 35A so as to be connected. However, the configuration of one clip may include a plurality of, for example, three sandwiching piece portions, and an entry piece portion is arranged between them, and the sandwiching piece portions are not a pair, but two or more pairs. It may consist of multiple pairs. Moreover, the structure which clamps an uncoated part between the clip parts of an adjacent clip by combining several clips of the structure which has one clip part may be sufficient.

  (4) In the embodiment described above, the clip 35 has a form in which a flat plate having a uniform thickness is bent by a press or the like, but the thickness of the clip is not necessarily constant. For example, when the stress applied to the part due to the foil exposed part being pulled is extremely high, the distance to the nearest entry piece in each foil exposed part is shortened by increasing the thickness of the entry piece. Thus, it is possible to provide a configuration in which stress is not easily applied to each foil exposed portion. Thereby, it becomes possible to further suppress the foil breakage in the exposed foil portion and the separation of the active material in the active material forming portion connected thereto.

  (5) In the above-described embodiment, the battery 10 is illustrated as including one power generation element 20, but is not limited thereto, and the number of power generation elements may be two or three or more. Good. Moreover, when a power generation element consists of two or more, those connection forms may be parallel connection and may be series connection.

  (6) In the above-described embodiment, the power generation element 20 is illustrated as being wound in a flat shape, but is not limited thereto, and the wound shape may be other shapes such as a cylindrical shape, for example. Instead of winding, a positive electrode plate and a negative electrode plate may be laminated in plural layers with a separator interposed therebetween.

  (7) In the above-described embodiment, the nonaqueous electrolyte secondary battery 10 is exemplified as the electrochemical device. However, the present invention is not limited to this. For example, an aqueous electrolyte secondary battery may be used, or a battery using other electrolytes. There may be. Moreover, the capacitor accompanying an electrochemical phenomenon like a lithium ion capacitor may be sufficient.

  (8) In the above-described embodiment, not all of the above-described advantages and effects lead to the essential constituent elements of the present invention, and the present invention can be freely designed to realize each of the above-described advantages and effects. It is sufficient to provide a degree and realize at least one advantage or effect.

10: non-aqueous electrolyte secondary battery (electrochemical device), 11: case (casing), 12: lid, 13: positive electrode terminal (external terminal), 14: negative electrode terminal (external terminal), 20: power generation element, 21 : Positive electrode plate (electrode plate), 21A, 25A: coated portion (active material forming portion), 21B, 25B: uncoated portion (foil exposed portion), 22, 26: welded portion, 25: negative electrode plate (electrode plate) ), 30: positive electrode current collector (current collector), 30A, 31A: body portion, 30B, 31B: connection portion (connection piece), 31: negative electrode current collector (current collector), 35: clip, 35A: Nipping piece, 35B: entry piece

Claims (5)

Laminating an electrode plate comprising: an active material forming part having an active material layer formed on the surface of the conductive foil; and a foil exposed part that is located at an edge of the conductive foil and exposes the conductive foil from the active material Power generation element
A casing for housing the power generation element;
An external terminal provided on the casing;
A current collector having a main body portion connected to the external terminal, and a plurality of connection pieces extending from the main body portion along a laminated portion of the foil exposed portion in the power generation element;
A sandwiching piece portion that sandwiches at least the laminated portion of the foil exposed portion in the thickness direction; and a portion that is divided into the laminated portion of the foil exposed portion to divide the laminated portion in the thickness direction; A clip that is a separate part from the current collector that is welded together with the laminated portion of the foil exposed portion with respect to the connection piece, and an entry piece portion that sandwiches the divided laminated portion therebetween.
An electrochemical device comprising:   The electrochemical device according to claim 1, wherein the clip is provided for each connection piece.   Before the welding to the laminated portion of the foil exposed portion, the clip is formed by integrally forming the flat plate-shaped sandwiching piece portion and the entry piece portion having a V-shaped cross section from a metal plate. 2 or 3, wherein each piece of the V-shaped portion is compressed from both sides and is in close contact with each other when welded to the laminated portion of the foil exposed portion. The electrochemical device according to claim 2.   The electrochemical device according to any one of claims 1 to 3, wherein the sandwiching pieces are paired.   The electrochemical device according to any one of claims 1 to 4, wherein the connection piece is sandwiched by the clip from both sides in the thickness direction together with the laminated portion of the exposed foil portion. .

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