JP7205719B2 - battery - Google Patents

Description

The present invention relates to batteries.

Batteries such as lithium-ion secondary batteries are widely used as portable power sources for personal computers and mobile terminals, or as power sources for driving vehicles such as EVs (electric vehicles), HVs (hybrid vehicles), and PHVs (plug-in hybrid vehicles). there is For example, the secondary battery disclosed in Patent Document 1 has an external terminal to which a busbar (connection member) can be fixed by welding. A constricted portion is provided at a position between the welding surface and the connecting portion of the external terminal of the battery. The width of the narrowed portion is smaller than the maximum width of either the welded portion or the connection portion of the external terminal.

JP 2014-235870 A

In the conventional battery described above, the constricted portion of the external terminal is narrower than the other portions, so the resistance of the constricted portion tends to be high. Therefore, when a current flows through the external terminal, there is a possibility that the temperature is likely to rise in the vicinity of the narrowed portion where the resistance is high. If the temperature of the external terminal rises excessively, it is conceivable that the sealing performance of the sealing member that seals the gap between the members may deteriorate. On the other hand, when the constricted portion is not provided, when an external force is applied to the external terminal, the external force is not absorbed by the constricted portion. As a result, the external force applied to the external terminals may degrade the sealing performance of the sealing member.

SUMMARY OF THE INVENTION A typical object of the present invention is to provide a battery capable of appropriately suppressing deterioration of sealing performance of a gap by a sealing member.

In order to achieve such an object, the battery of one aspect disclosed herein includes a case that houses a power generation element, an external terminal that is arranged outside the case and connected to a bus bar, and a terminal that connects the case and the external terminal. It has a shaft part inserted through a through hole formed in each, and a crimped part connected to the external terminal by being crimped outside the case, and electrically connected to the electrode body inside the case. and an insulating member disposed between the case and the external terminal and including an enclosing portion that protrudes in the axial direction of the shaft portion and surrounds at least a portion of the outer periphery of the external terminal. When viewed from the axial direction of the shaft portion, the width of the external terminal in a direction intersecting the direction connecting the position where the bus bar is connected and the crimped portion is the first region where the crimped portion is located. is larger than the width of the second region between the position where the bus bar is connected and the first region, and the enclosing portion of the insulating member extends around the first region of the external terminal. characterized by being in contact with at least a portion of the

The external terminal of the battery having the above configuration is not provided with a constricted portion that tends to increase the resistance. Therefore, an increase in Joule heat generated when current flows through the external terminals is suppressed. At least a part of the periphery of the first region of the external terminal is in contact with the surrounding portion of the insulating member, thereby increasing the heat transfer path from the external terminal to the insulating member. As a result, the temperature rise of the external terminals is further suppressed. Moreover, even when an external force is applied to the external terminal, the stress concentrates on the boundary between the first region and the second region. Therefore, deterioration of the sealing performance of the gap by the sealing member due to external force is also suppressed. Therefore, deterioration of the sealing performance of the gap by the sealing member is appropriately suppressed.

1 is a vertical cross-sectional view showing the configuration of a battery 1 of this embodiment; FIG. It is a longitudinal cross-sectional view of the vicinity of the negative electrode terminal member 4B. It is a top view of the vicinity of the negative electrode terminal member 4B.

One typical embodiment of the present disclosure will be described in detail below with reference to the drawings. Matters other than those specifically referred to in this specification that are necessary for implementation can be grasped as design matters for those skilled in the art based on the prior art in the relevant field. The present invention can be implemented based on the contents disclosed in this specification and common general technical knowledge in the field. In the drawings below, members and portions having the same function are denoted by the same reference numerals. Also, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relationships.

As used herein, the term “battery” is a general term for power storage devices from which electrical energy can be extracted, and is a concept that includes primary batteries and secondary batteries. "Secondary battery" refers to a general electricity storage device that can be repeatedly charged and discharged, and in addition to so-called storage batteries (that is, chemical batteries) such as lithium ion secondary batteries, nickel hydrogen batteries, and nickel cadmium batteries, electric double layer capacitors, etc. It contains a capacitor (ie a physical battery). Hereinafter, the battery according to the present disclosure will be described in detail by exemplifying a flat prismatic lithium-ion secondary battery, which is a type of battery. However, the batteries according to the present disclosure are not intended to be limited to those described in the following embodiments.

<Overall configuration of the battery>
An overall configuration of a battery 1 according to the present disclosure will be described with reference to FIG. A battery 1 illustrated in FIG. 1 is a lithium ion secondary battery, and includes a case 2 , an electrode body (corresponding to a power generation element) 3 , and an electrolyte 35 . The case 2 accommodates the electrode assembly 3 and the electrolytic solution 35 in a hermetically sealed state. The shape of the case 2 in this embodiment is a flat square. The case 2 includes a box-shaped main body 21 having an opening at one end and a plate-like lid member 22 closing the opening of the main body. The main body 21 and the lid member 22 are integrated by welding or the like. As the material of the case 2, for example, a metal material such as aluminum which is lightweight and has good thermal conductivity can be used. As an example, the electrode body 3 in the present embodiment uses a wound electrode body in which a long positive electrode body, a negative electrode body, and a separator are superimposed and wound. As an example, the electrolyte 35 in this embodiment is a non-aqueous electrolyte containing a lithium salt.

The lid member 22 has a rectangular plate shape. A pair of electrode terminal members 4 (a positive electrode terminal member 4A and a negative electrode terminal member 4B) are provided at both ends of the lid member 22 in the longitudinal direction (horizontal direction in FIG. 1). Specifically, a positive electrode terminal member 4A is provided at one longitudinal end (left end in FIG. 1) of the lid member 22, and a negative electrode terminal member 4B is provided at the other longitudinal end (right end in FIG. 1). It is

The positive terminal member 4A includes a positive external terminal (not shown), a positive internal terminal 7A, and a positive collector terminal 8A. A positive external terminal is arranged outside the case 2 . The positive internal terminal 7A is arranged inside the case 2 . Also, the positive electrode internal terminal 7A is connected to the positive electrode external terminal through a first through hole provided in the case 2 . The positive collector terminal 8A is electrically connected to the positive electrode 3A of the electrode body 3 and the positive electrode internal terminal 7A inside the case 2 .

The negative terminal member 4B includes a negative external terminal 6B (see FIG. 2), a negative internal terminal 7B, and a negative collector terminal 8B. The negative external terminal 6B is arranged outside the case 2 . The negative internal terminal 7B is arranged inside the case 2 . Also, the negative internal terminal 7B is connected to the negative external terminal 6B through a first through hole 23B (see FIG. 2) provided in the case 2 . The negative collector terminal 8B is electrically connected to the negative electrode 3B of the electrode assembly 3 and the negative internal terminal 7B inside the case 2 . Each member constituting the positive electrode terminal member 4A and the negative electrode terminal member 4B is appropriately formed of a metal or the like having high conductivity.

<Electrode terminal member>
The structure of the electrode terminal member 4 (the positive electrode terminal member 4A and the negative electrode terminal member 4B) in the battery 1 will be described in detail with reference to FIGS. 2 and 3. FIG. The structures of the positive electrode terminal member 4A and the negative electrode terminal member 4B in the present embodiment are formed in a substantially symmetrical structure with the center in the longitudinal direction of the battery 1 as the center. Therefore, the configuration of the negative electrode terminal member 4B will be described in detail below, and the description of the configuration of the positive electrode terminal member 4A will be omitted.

The negative external terminal 6B is plate-shaped and has a through hole 62B. An insulating member 15B is arranged between the case 2 (the lid member 22 in this embodiment) and the negative electrode external terminal 6B. The insulating member 15B is made of an insulating material. The insulating member 15B includes a flat plate portion 16B and an enclosing portion 18B. A through hole 17B is formed in the flat plate portion 16B. The enclosing portion 18B extends upward (that is, in the axial direction of the shaft portion 75B described later) from the end of the flat plate portion 16B. The surrounding portion 18B surrounds at least a portion of the outer circumference of the negative electrode external terminal 6B (entire circumference in this embodiment). In this embodiment, the insulating member 15B extends in the extending direction of the cover member 22 of the case 2 (horizontal direction in FIGS. 1 to 3). Specifically, the extending direction of the enclosing portion 18B of the insulating member 15B and the extending direction of the cover member 22 of the case 2 are parallel. Therefore, the insulating member 15B does not have a portion near the boundary between the lid member 22 and the main body 21 . Therefore, when the cover member 22 and the main body 21 are connected by welding or the like, the possibility that the insulating member 15B is affected by heat or the like can be reduced.

The case 2 (in this embodiment, the lid member 22 of the case 2) is provided with a through hole 23B through which the negative electrode internal terminal 7B is inserted. The negative internal terminal 7B includes a support portion 71B, a shaft portion 75B, and a caulking portion 76B. The support portion 71B has a substantially plate-like plate surface. The shaft portion 75B is columnar (columnar in this embodiment) and extends vertically (upward in FIG. 2) from the plate surface of the support portion 71B. The cross section of the shaft portion 75B is smaller than the plate surface of the support portion 71B. The shaft portion 75B is inserted through the through hole 23B in the case 2 and the through hole 62B in the negative external terminal 6B. The crimped portion 76B is connected to the negative external terminal 6B by crimping the tip portion (upper end portion in FIG. 2) of the shaft portion 75B.

In addition, when the strength of the material of the negative electrode internal terminal 7B is higher than the strength of the material of the negative electrode external terminal 6B, the tip portion of the shaft portion 75B is crimped so that the negative electrode external terminal 6B around the crimped portion 76B (through hole 62B) is crimped. is pushed wide. Therefore, as an example, the negative electrode external terminal 6B extending with substantially the same width is prepared, and the tip portion of the shaft portion 75B is crimped to widen the width of the negative electrode external terminal 6B around the crimped portion 76B (through hole 62B). good too. As another example, a negative external terminal 6B having a wide width around the crimped portion 76B (through hole 62B) may be prepared in advance.

A seal member 9B is arranged between the negative electrode internal terminal 7B and the inner surface 25B of the case 2 (the lid member 22 in this embodiment). The seal member 9B is made of an insulating material. Further, the seal member 9B may be made of a material (such as resin) having elasticity and electrolyte resistance. The sealing member 9B insulates between the negative internal terminal 7B and the case 2 . Moreover, the sealing member 9B seals between the negative electrode internal terminal 7B and the inner surface 25B of the case 2 by being in close contact with the negative electrode internal terminal 7B and the inner surface 25B of the case 2 . In addition, the inner surface 25B of the case 2 is the surface facing the inside of the case 2 (the lower surface of the lid member 22 in FIG. 2).

The seal member 9B includes a base portion 91B, a through hole 92B, and a tubular portion 93B. The base portion 91B is formed in a substantially flat plate shape. Note that the base portion 91B may be deformed by being compressed between the negative electrode internal terminal 7B and the inner surface of the case 2 . The through-hole 92B penetrates through a substantially central portion of the base portion 91B in the thickness direction (vertical direction in FIG. 2). The tubular portion 93B is a tubular (cylindrical in this embodiment) portion that protrudes outward (upward in FIG. 2) of the case 2 from the periphery of the through hole 92B. The tubular portion 93B is fitted into the through hole 23B provided in the lid member 22 .

A bus bar 10 can be arranged on the external terminals 6 (positive external terminal 6A and negative external terminal 6B). For example, an assembled battery can be configured by connecting a plurality of batteries 1 via bus bars 10 . A method for connecting the bus bar 10 to the external terminal 6 can be selected as appropriate. For example, the busbar 10 may be arranged on the external terminal 6 and fixed to the external terminal 6 by welding. For example, the electrode terminal member 4 may be provided with a bolt, and the bus bar 10 may be provided with a through hole. In this case, the bolts of the electrode terminal members 4 may be inserted through the through holes of the busbars 10 so that the busbars 10 are arranged on the external terminals 6 . The busbar 10 may be fixed to the external terminal 6 by fastening a nut to a bolt inserted through the through hole of the busbar 10 .

As shown in FIG. 3, when viewed from the axial direction (that is, from above in FIG. 2) of the shaft portion 75B (see FIG. 2) of the negative electrode internal terminal 7B, the region where the crimped portion 76B is located in the negative electrode external terminal 6B is A first region R1 is defined as a second region R2. In this case, the width of the negative external terminal 6B in the direction intersecting the direction connecting the position where the bus bar 10 is connected and the crimped portion 76B (that is, the vertical direction in FIG. 3) is noted. In the negative external terminal 6B of this embodiment, the width W1 of the first region R1 is larger than the width W2 of the second region R2. Therefore, the negative external terminal 6B does not have a constricted portion that may increase the resistance. Therefore, Joule heat is less likely to occur when current flows through the negative electrode external terminal 6B. Therefore, heat generation of the negative electrode external terminal 6B can be suppressed. Also, when an external force is applied to the negative external terminal 6B (for example, when the bus bar 10 is fixed to the negative external terminal 6B, etc.), stress concentrates on the boundary between the first region R1 and the second region R2. As a result, the negative external terminal 6B is deformed at the boundary, so that impact and vibration can be absorbed appropriately. In this manner, the load applied to the sealing member 9B can be reduced by appropriately absorbing impact and vibration while reducing heat generation of the negative external terminal 6B. This can reduce the deterioration of the sealing performance of the seal member 9B.

The enclosing portion 18B of the insulating member 15B contacts at least part of the circumference of the first region R1 of the negative electrode external terminal 6B. In the present embodiment, the widthwise end of the first region R1 contacts the enclosing portion 18B. This increases heat transfer paths. Therefore, heat generation around the caulked portion 76B of the negative electrode external terminal 6B can be further reduced.

As described above, the structures of the positive terminal member 4A and the negative terminal member 4B are substantially symmetrical with respect to the center in the longitudinal direction of the battery 1 . Therefore, by configuring the positive electrode terminal member 4A with the same structure as the negative electrode terminal member 4B, the same function and effect as those of the negative electrode terminal member 4B can be obtained.

The technology disclosed in the above embodiment is merely an example. Therefore, it is also possible to modify the techniques exemplified in the above embodiments. As described above, in this embodiment, the insulating member 15B extends in the extension direction of the lid member 22 of the case 2 . Specifically, the extending direction of the enclosing portion 18B of the insulating member 15B and the extending direction of the cover member 22 of the case 2 are parallel. However, the insulating member 15B does not have to extend in the extending direction of the cover member 22 of the case 2 . The direction in which the enclosing portion 18B of the insulating member 15B extends and the direction in which the lid member 22 of the case 2 extends may not be parallel.

1 Battery 2 Case 3 Electrode body 4 Electrode terminal member 4A Positive electrode terminal member 4B Negative electrode terminal member 6B Negative electrode external terminal 7B Negative electrode internal terminal 9B Seal member 10 Bus bar 15B Insulating member 18B Surrounding portion 23B Through hole 62B Through hole 75B Shaft portion 76B Crimp portion R1 first region R2 second region

Claims (2)

a case housing the power generation element;
an external terminal arranged outside the case and directly connected to a bus bar;
and a crimped portion connected to the external terminal by being crimped outside the case. an internal terminal electrically connected to the electrode body;
an insulating member provided between the case and the external terminal, the insulating member including an enclosing portion that protrudes in the axial direction of the shaft portion and encloses at least a portion of the outer periphery of the external terminal;
with
The external terminal has a flat plate shape extending along the case, and in a first direction connecting a position where the bus bar is directly connected and the crimped portion,
a region to which the bus bar is directly connected;
a first region where the crimped portion is located;
a second region provided between the region to which the bus bar is directly connected and the first region and extending with a predetermined width along the first direction;
has
When viewed from the axial direction of the shaft portion, the width of the first region of the external terminal is greater than the width of the second region in a second direction that intersects with the first direction. big,
The first region of the external terminal has both ends in the second direction in contact with the enclosing portion of the insulating member, while the region of the external terminal to which the bus bar is directly connected has the end in the second direction. is spaced apart from the enclosing portion of the insulating member;
battery. The busbar is joined to the external terminal by welding,
A battery according to claim 1 .

Images