JP2022028968A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a more reliable secondary battery.

SOLUTION: A secondary battery according to an embodiment of the present invention includes an electrode body 3 including a positive electrode plate and a negative electrode plate, an exterior body having an opening and accommodating the electrode body 3, a sealing plate that has a terminal insertion hole and seals the opening, a terminal that penetrates the terminal insertion hole, and a current collector that has a terminal connection hole and is electrically connected to the positive electrode plate or the negative electrode plate, and the terminal is arranged in the terminal connection hole, and the terminal connection hole has a first hole portion and a second hole portion connected to the first hole portion, and the first hole portion is provided on the electrode body side from the second hole portion, the inner dimension of the first hole portion is larger than the inner dimension of the second hole portion, and the terminal has a caulked portion having an outer diameter larger than the inner diameter of the portion having the smallest inner diameter in the terminal connection hole, the caulked portion and the current collector are joined by a solidification portion 70 in which at least one of the caulked portion and the current collector is melted and solidified, and a recess 70a is formed in the solidification portion 70, and in the thickness direction of the current collector, the bottom of the recess 70a is located closer to the electrode body than the second hole portion.

SELECTED DRAWING: Figure 9

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a secondary battery.

Square secondary batteries such as alkaline secondary batteries and non-aqueous electrolyte secondary batteries are used in driving power sources of electric vehicles (EV) and hybrid electric vehicles (HEV, PHEV).

In these square secondary batteries, a battery case is composed of a bottomed cylindrical square exterior body having an opening and a sealing plate for sealing the opening. An electrode body composed of a positive electrode plate, a negative electrode plate and a separator is housed in the battery case together with the electrolytic solution. A positive electrode terminal and a negative electrode terminal are attached to the sealing plate. The positive electrode terminal is electrically connected to the positive electrode plate via the positive electrode current collector, and the negative electrode terminal is electrically connected to the negative electrode plate via the negative electrode current collector.

In such a square secondary battery, it is preferable that the positive electrode terminal and the positive electrode current collector and the negative electrode terminal and the negative electrode current collector are connected by caulking and welding, respectively. For example, Patent Document 1 below discloses a technique of laser welding a caulked portion of a terminal to a current collector.

Japanese Unexamined Patent Publication No. 2011-076867

One object of the present invention is to provide a secondary battery in which the reliability of the connection portion between the terminal and the current collector is further improved.

The uniform secondary battery of the present invention has an electrode body including a positive electrode plate and a negative electrode plate, an exterior body having an opening and accommodating the electrode body, and a sealing plate having a terminal insertion hole and sealing the opening. It has a terminal that penetrates the terminal insertion hole, a terminal connection hole, and a current collector that is electrically connected to the positive electrode plate or the negative electrode plate. The hole has a first hole portion and a second hole portion connected to the first hole portion, the first hole portion is provided on the electrode body side from the second hole portion, and the inner dimension of the first hole portion is The terminal has a caulked portion having an outer diameter larger than the inner diameter of the portion having the smallest inner diameter in the terminal connection hole, which is larger than the inner dimension of the second hole portion, and the caulked portion and the current collector have the caulked portion and the current collector. At least one of the current collectors is joined by a solidified portion that has been melted and solidified, and a recess is formed in the solidified portion. In the thickness direction of the current collector, the bottom of the recess is an electrode from the second hole. Located on the body side.

The terminal connection hole preferably has a tapered portion whose inner diameter gradually increases toward the direction away from the sealing plate.

It is preferable that at least a part of the caulked portion protrudes toward the electrode body side rather than the surface on the electrode body side in the current collector.

It is preferable that the thickness of the portion of the solidified portion located at the bottom of the recess in the thickness direction of the current collector is larger than the thickness of the portion of the solidified portion located on the side wall of the recess in the radial direction of the terminal connection hole.

According to the present invention, it is possible to provide a highly reliable secondary battery.

It is a perspective view of the secondary battery which concerns on embodiment. FIG. 3 is a cross-sectional view taken along the line II-II in FIG. It is a top view of the positive electrode plate which concerns on embodiment. It is a top view of the negative electrode plate which concerns on embodiment. It is a top view of the electrode body element which concerns on embodiment. It is a figure which shows the state which connected the positive electrode tab group to the positive electrode current collector, and connected the negative electrode tab group to the negative electrode current collector. It is a figure which shows the surface of the sealing plate on the electrode body side after the 1st positive electrode current collector and the 1st negative electrode current collector are attached. (A) is a cross-sectional view taken along the short side of the sealing plate in the vicinity of the positive electrode terminal before caulking the positive electrode terminal. (B) is a cross-sectional view taken along the short side of the sealing plate in the vicinity of the positive electrode terminal after caulking the positive electrode terminal. (C) is a cross-sectional view taken along the short side of the sealing plate in the vicinity of the positive electrode terminal after welding the positive electrode terminal and the first positive electrode current collector. (A) is an enlarged view of the vicinity of the crimped portion of the positive electrode terminal in FIG. 8 (b). (B) is an enlarged view of the vicinity of the crimped portion of the positive electrode terminal in FIG. 8 (c). It is a figure which shows the surface of the sealing plate on the electrode body side after attaching the 2nd positive electrode current collector to the 1st positive electrode current collector, and attaching the 2nd negative electrode current collector to the 1st negative electrode current collector. It is sectional drawing along the longitudinal direction of the sealing plate near the negative electrode terminal. 11 is an enlarged view of the vicinity of the connection portion between the first negative electrode current collector and the second negative electrode current collector in FIG. 13A and 13B are perspective views of the sealing plate and the cover member after each component is attached. It is sectional drawing along the short side of the sealing plate near the positive electrode terminal. It is sectional drawing along the longitudinal direction of the sealing plate near the positive electrode terminal.

The configuration of the square secondary battery 20 as the secondary battery according to the embodiment will be described below. The present invention is not limited to the following embodiments.

As shown in FIGS. 1 and 2, the square secondary battery 20 includes a battery case 100 including a bottomed square cylindrical outer body 1 having an opening and a sealing plate 2 for sealing the opening of the square outer body 1. .. The square exterior body 1 and the sealing plate 2 are preferably made of metal, and are preferably made of, for example, aluminum or an aluminum alloy. In the square exterior body 1, an electrode body 3 in which a positive electrode plate and a negative electrode plate are laminated via a separator is housed together with an electrolyte.

A positive electrode tab 40 and a negative electrode tab 50 are provided at the end of the electrode body 3 on the sealing plate 2 side. The positive electrode tab 40 is electrically connected to the positive electrode terminal 7 via the second positive electrode current collector 6b and the first positive electrode current collector 6a. The negative electrode tab 50 is electrically connected to the negative electrode terminal 9 via the second negative electrode current collector 8b and the first negative electrode current collector 8a.

The first positive electrode current collector 6a, the second positive electrode current collector 6b, and the positive electrode terminal 7 are preferably made of metal, more preferably aluminum or an aluminum alloy. An external insulating member 10 made of resin is arranged between the positive electrode terminal 7 and the sealing plate 2. A resin internal insulating member 11 is arranged between the first positive electrode current collector 6a and the second positive electrode current collector 6b and the sealing plate 2.

The first negative electrode current collector 8a, the second negative electrode current collector 8b, and the negative electrode terminal 9 are preferably made of metal, more preferably copper or a copper alloy. Further, it is preferable that the negative electrode terminal 9 has a portion made of aluminum or an aluminum alloy and a portion made of copper or a copper alloy. In this case, it is preferable to connect the portion made of copper or a copper alloy to the first negative electrode current collector 8a so that the portion made of aluminum or an aluminum alloy protrudes to the outside of the sealing plate 2. An external insulating member 12 made of resin is arranged between the negative electrode terminal 9 and the sealing plate 2. A resin internal insulating member 13 is arranged between the first negative electrode current collector 8a and the second negative electrode current collector 8b and the sealing plate 2.

An electrode body holder 14 made of a resin sheet made of resin is arranged between the electrode body 3 and the square exterior body 1. The electrode body holder 14 is preferably formed by bending a resin insulating sheet into a bag shape or a box shape. The sealing plate 2 is provided with an electrolytic solution injection hole 15, and the electrolytic solution injection hole 15 is sealed by a sealing member 16. The sealing plate 2 is provided with a gas discharge valve 17 that breaks when the pressure inside the battery case 100 exceeds a predetermined value and discharges the gas inside the battery case 100 to the outside of the battery case 100. An annular protrusion 2c is provided around the gas discharge valve 17, which is the surface of the sealing plate 2 on the inner side of the battery.

Next, a manufacturing method of the square secondary battery 20 and details of each configuration will be described.

[Positive plate]
FIG. 3 is a plan view of the positive electrode plate 4. The positive electrode plate 4 has a main body portion in which a positive electrode active material mixture layer 4b containing a positive electrode active material is formed on both sides of a rectangular positive electrode core body 4a. The positive electrode core body 4a protrudes from the end side of the main body portion, and the protruding positive electrode core body 4a constitutes the positive electrode tab 40. The positive electrode tab 40 may be a part of the positive electrode core 4a as shown in FIG. 3, or another member may be connected to the positive electrode core 4a to form the positive electrode tab 40. Further, it is preferable that the positive electrode protective layer 4d having an electric resistance larger than the electric resistance of the positive electrode active material mixture layer 4b is provided in the portion of the positive electrode tab 40 adjacent to the positive electrode active material mixture layer 4b. It is preferable to use a metal foil such as an aluminum foil or an aluminum alloy foil as the positive electrode core 4a. It is preferable to use a lithium transition metal composite oxide or the like as the positive electrode active material.

[Negative electrode plate]
FIG. 4 is a plan view of the negative electrode plate 5. The negative electrode plate 5 has a main body portion in which a negative electrode active material mixture layer 5b containing a negative electrode active material is formed on both sides of a rectangular negative electrode core body 5a. The negative electrode core 5a protrudes from the end side of the main body, and the protruding negative electrode core 5a constitutes the negative electrode tab 50. The negative electrode tab 50 may be a part of the negative electrode core 5a as shown in FIG. 4, or another member may be connected to the negative electrode core 5a to form the negative electrode tab 50. It is preferable to use a metal foil such as a copper foil or a copper alloy foil as the negative electrode core 5a. It is preferable to use a carbon material, a silicon material, or the like as the negative electrode active material.

[Making electrode body elements]
Fifty positive electrode plates 4 and 51 negative electrode plates 5 are manufactured by the above method, and these are laminated via a rectangular separator made of polyolefin to form a laminated electrode body element (first electrode body element 3a, The second electrode body element 3b) is manufactured. As shown in FIG. 5, in the laminated electrode body element (first electrode body element 3a, second electrode body element 3b), the positive electrode tab 40 of each positive electrode plate 4 is laminated on one end. The positive electrode tab group (first positive electrode tab group 40a, second positive electrode tab group 40b) and the negative electrode tab group (first negative electrode tab group 50a, second negative electrode tab group 50b) in which the negative electrode tabs 50 of each negative electrode plate 5 are laminated. Have.

Separator is arranged on both outer surfaces of the electrode body element, and each electrode plate and the separator can be fixed in a laminated state by tape or the like. Alternatively, an adhesive layer may be provided on the separator so that the separator and the positive electrode plate 4 and the separator and the negative electrode plate 5 are adhered to each other. The positive electrode plate 4 and the negative electrode plate 5 may be laminated by folding the separator into a zigzag shape.

It is preferable that the size of the separator in a plan view is the same as that of the negative electrode plate 5 or larger than that of the negative electrode plate 5. The positive electrode plate 4 or the negative electrode plate 5 may be arranged between the two separators, and the peripheral edge of the separator may be heat-welded, and then the positive electrode plate 4 and the negative electrode plate 5 may be laminated. It is also possible to wind the band-shaped positive electrode plate and the band-shaped negative electrode plate via the band-shaped separator to form a wound electrode body element.

[Current collector and tab connection]
Two electrode body elements are produced by the above-mentioned method, and are referred to as a first electrode body element 3a and a second electrode body element 3b, respectively. The first electrode body element 3a and the second electrode body element 3b may have exactly the same configuration or may have different configurations. Here, the plurality of positive electrode tabs 40 of the first electrode body element 3a constitute the first positive electrode tab group 40a. A plurality of negative electrode tabs 50 of the first electrode body element 3a constitute the first negative electrode tab group 50a. A plurality of positive electrode tabs 40 of the second electrode body element 3b constitute the second positive electrode tab group 40b. A plurality of negative electrode tabs 50 of the second electrode body element 3b constitute the second negative electrode tab group 50b.

In FIG. 6, the first positive electrode tab group 40a and the second positive electrode tab group 40b are connected to the second positive electrode current collector 6b, and the first negative electrode tab group 50a and the second negative electrode tab group 50b are connected to the second negative electrode current collector 8b. It is a figure which shows the state which connected. A second positive electrode current collector 6b and a second negative electrode current collector 8b are arranged between the first electrode body element 3a and the second electrode body element 3b. Then, the first positive electrode tab group 40a and the second positive electrode tab group 40b are arranged on the second positive electrode current collector 6b. The first negative electrode tab group 50a and the second negative electrode tab group 50b are arranged on the second negative electrode current collector 8b. The first positive electrode tab group 40a and the second positive electrode tab group 40b are each welded and connected to the second positive electrode current collector 6b to form a welded portion 60. The first negative electrode tab group 50a and the second negative electrode tab group 50b are each welded and connected to the second negative electrode current collector 8b to form a welded portion 61. The welding method is preferably ultrasonic welding or resistance welding. It can also be connected by laser welding. In the positive electrode current collector 6, a current collector opening 6e is provided at a position facing the electrolytic solution injection hole 15.

The second positive electrode current collector 6b is provided with an opening 6c. The opening 6c is provided inside the thin portion 6d. The second negative electrode current collector 8b is provided with an opening 8c. The opening 8c is provided inside the thin portion 8d.

[Attachment of each part to the sealing plate]
The external insulating member 10 is arranged on the outer surface side of the battery around the positive electrode terminal insertion hole 2a of the sealing plate 2. The internal insulating member 11 and the first positive electrode current collector 6a are arranged on the inner surface side of the battery around the positive electrode terminal insertion hole 2a of the sealing plate 2. Then, from the outside of the battery, the positive electrode terminal 7 is provided with a through hole of the external insulating member 10, a positive electrode terminal insertion hole 2a of the sealing plate 2, a through hole of the internal insulating member 11, and a terminal connection hole of the first positive electrode current collector 6a. The tip of the positive electrode terminal 7 is crimped onto the first positive electrode current collector 6a. As a result, the positive electrode terminal 7 and the first positive electrode current collector 6a are fixed to the sealing plate 2. It is preferable that the crimped portion of the positive electrode terminal 7 and the first positive electrode current collector 6a are welded and connected.

The external insulating member 12 is arranged on the outer surface side of the battery around the negative electrode terminal insertion hole 2b of the sealing plate 2. The internal insulating member 13 and the first negative electrode current collector 8a are arranged on the inner surface side of the battery around the negative electrode terminal insertion hole 2b of the sealing plate 2. Then, from the outside of the battery, the negative electrode terminal 9 is inserted into the through hole of the external insulating member 12, the negative electrode terminal insertion hole 2b of the sealing plate 2, the through hole of the internal insulating member 13, and the terminal connection hole of the first negative electrode current collector 8a. The tip of the negative electrode terminal 9 is caulked onto the first negative electrode current collector 8a. As a result, the negative electrode terminal 9 and the first negative electrode current collector 8a are fixed to the sealing plate 2. It is preferable that the crimped portion of the negative electrode terminal 9 and the first negative electrode current collector 8a are welded and connected.

FIG. 7 shows a positive electrode terminal 7, an external insulating member 10, an internal insulating member 11, a first positive electrode current collector 6a, a negative electrode terminal 9, an external insulating member 12, an internal insulating member 13, and a first negative electrode current collector. It is a figure which shows the surface of the sealing plate 2 on the inner surface side of a battery after the body 8a is attached. The internal insulating member 11 on the positive electrode side has a base portion 11a arranged along the sealing plate 2. A pair of second wall portions 11b protruding from the base portion 11a toward the electrode body 3 are provided at both ends of the base portion 11a in the lateral direction of the sealing plate 2. A pair of first wall portions 11c protruding from the base portion 11a toward the electrode body 3 are provided at both ends of the base portion 11a in the lateral direction of the sealing plate 2. On the outer peripheral edge of the base portion 11a of the inner side insulating member 11, an outer peripheral rib 11d is provided at a position where the second wall portion 11b and the first wall portion 11c are not provided. As shown in FIG. 7, the first positive electrode current collector 6a and the positive electrode terminal 7 are connected between the pair of first wall portions 11c.

A current collector projection 6x is provided on the surface of the first positive electrode current collector 6a on the electrode body 3 side. The shape of the collector protrusion 6x in a plan view is preferably a shape having a longitudinal direction and a lateral direction, such as a rectangular shape, an elliptical shape, or a track shape.

The internal insulating member 13 on the negative electrode side has a base portion 13a arranged along the sealing plate 2. A pair of third wall portions 13b protruding from the base portion 13a toward the electrode body 3 are provided at both ends of the base portion 13a in the lateral direction of the sealing plate 2. On the outer peripheral edge of the base portion 13a of the inner side insulating member 13, an outer peripheral rib 13c is provided at a position where the third wall portion 13b is not provided.

A current collector projection 8x is provided on the surface of the first negative electrode current collector 8a on the electrode body 3 side. The shape of the collector protrusion 8x in a plan view is preferably a shape having a longitudinal direction and a lateral direction, such as a rectangular shape, an elliptical shape, or a track shape.

[Connection between terminal and current collector]
Details of the connection method between the positive electrode terminal 7 and the first positive electrode current collector 6a, the connection method between the negative electrode terminal 9 and the first negative electrode current collector 8a, and the connection method between the negative electrode terminal 9 and the first negative electrode current collector 8a are taken as examples. explain. The positive electrode terminal 7 and the first positive electrode current collector 6a can also be connected by the same method as the connection between the negative electrode terminal 9 and the first negative electrode current collector 8a.

As shown in FIG. 8A, the insertion portion 9b provided in the flange portion 9a of the negative electrode terminal 9 is inserted into the terminal connection hole 8y provided in the first negative electrode current collector 8a. The terminal connection hole 8y has a tapered portion 8z whose inner diameter gradually increases toward the end portion on the side farther from the sealing plate 2. The insertion portion 9b is inserted into the terminal connection hole 8y from the sealing plate 2 side. The negative electrode terminal 9 preferably has a first metal portion 9x made of a first metal and a second metal portion 9y made of a second metal different from the first metal. Aluminum or an aluminum alloy is preferable as the first metal. Copper or a copper alloy is preferable as the second metal. A layer made of a third metal may be provided between the first metal portion 9x and the second metal portion 9y. Nickel or the like is preferable as the third metal.

Next, as shown in FIG. 8B, the tip of the insertion portion 9b of the negative electrode terminal 9 is deformed so as to expand the diameter to form the caulking portion 9c. As a result, the region on the tip end side of the insertion portion 9b is caulked on the first negative electrode current collector 8a. The caulked portion 9c is caulked on the tapered portion 8z. Then, a gap 95 is formed between the tapered portion 8z and the insertion portion 9b. The caulked portion 9c has an outer diameter larger than the inner diameter of the portion having the smallest inner diameter in the terminal connection hole 8y. A part of the caulked portion 9c protrudes from the surface 8a1 on the side far from the sealing plate 2 in the first negative electrode current collector 8a in the direction away from the sealing plate 2. Further, it is preferable that the tip concave portion 9d is formed on the tip surface of the insertion portion 9b. When the tip recess 9d is formed on the tip surface of the insertion portion 9b, the caulking portion 9c is formed more stably. Next, by irradiating the gap 95 with an energy ray such as a laser, the caulked portion 9c and the tapered portion 8z of the first negative electrode current collector 8a are melted. Then, the melted portion solidifies, and as shown in FIG. 8 (c), the solidified portion 70 is formed. The negative electrode terminal 9 and the first negative electrode current collector 8a are joined by the solidifying portion 70. The molten metal constituting the negative electrode terminal 9 to the first negative electrode current collector 8a flows into the gap 95 and solidifies. A recess 70a is formed in the solidifying portion 70.

By connecting the negative electrode terminal 9 and the first negative electrode current collector 8a by the above method, a highly reliable square secondary battery 20 in which the negative electrode terminal 9 and the first negative electrode current collector 8a are more firmly connected is obtained. .. Further, the molten metal flows into the gap 95 generated between the caulked portion 9c of the negative electrode terminal 9 and the tapered portion 8z of the first negative electrode current collector 8a, and the recess 70a is formed in the solidified portion 70 where the molten metal is solidified. By doing so, it is possible to suppress the occurrence of overlap, which is a welding defect. Further, since it is possible to effectively suppress the shape of the solidified portion 70 from being raised, the square secondary battery 20 has a higher reliability and the solidified portion 70 is less likely to be damaged.

The bottom of the recess 70a is closer to the sealing plate 2 side than the surface 8a1 (upper surface of the first negative electrode current collector 8a in FIG. 9B) on the side far from the sealing plate 2 in the first negative electrode current collector 8a (FIG. 9 (FIG. 9). It is located below) in b). This makes it difficult for overlap, which is a welding defect, to occur during welding. Therefore, it is possible to effectively prevent a part of the solidifying portion 70 from being chipped and dropped, causing a short circuit. In addition, the solidified portion 70 is less likely to be damaged.

The negative electrode terminal so that the caulked portion 9c of the negative electrode terminal 9 projects in the direction away from the sealing plate 2 (upper in FIG. 8B) than the surface 8a1 on the side farther from the sealing plate 2 in the first negative electrode current collector 8a. The amount of melting of the negative electrode terminal 9 (volume of the melted portion) that melts by caulking 9 is the amount of melting of the first negative electrode current collector 8a that melts by irradiation of the energy ray (volume of the melted portion). ) It is preferable to make it larger. As a result, the molten metal easily enters the gap 95, and the negative electrode terminal 9 and the first negative electrode current collector 8a are more firmly connected.

The bottom portion and the side wall portion constituting the recess 70a are solidified portions 70 in which the metal melted by irradiation with energy rays is solidified. The thickness of the first negative electrode current collector 8a of the portion 70x located at the bottom of the recess 70a in the solidifying portion 70 in the thickness direction (vertical direction in FIG. 9B) is located on the side wall of the recess 70a in the solidifying portion 70. It is preferably larger than the thickness of the terminal connection hole 8y of the portion 70y in the radial direction (left-right direction in FIG. 9B). With such a configuration, the negative electrode terminal 9 and the first negative electrode current collector 8a are connected in a more preferable state. In addition, the solidified portion 70 is less likely to be damaged.

In the thickness direction of the sealing plate 2, it is preferable that the portion of the negative electrode terminal 9 farthest from the sealing plate 2 is not melted by irradiation with energy rays. As a result, the structure is such that the manufacturing apparatus, the jig, or other parts are unlikely to come into contact with the solidifying portion 70.

The energy ray may be a continuous oscillation type or a pulse type. The recess 70a is preferably formed in an annular shape when viewed from the thickness direction of the sealing plate 2 (direction perpendicular to the sealing plate 2).

[Connection between the 1st current collector and the 2nd current collector]
FIG. 10 shows the electrode body 3 side of the sealing plate 2 after the second positive electrode current collector 6b is attached to the first positive electrode current collector 6a and the second negative electrode current collector 8b is attached to the first negative electrode current collector 8a. It is a figure which shows the surface of. The second positive electrode current collector 6b to which the first positive electrode tab group 40a and the second positive electrode tab group 40b are connected is arranged on the base portion 11a of the internal insulating member 11. Further, a part of the second positive electrode current collector 6b is arranged on the first positive electrode current collector 6a. The thin portion 6d of the second positive electrode current collector 6b is welded and connected to the first positive electrode current collector 6a to form the welded portion 62. The welded portion 62 is formed at a position away from the opening 6c. It is preferable to form the welded portion 62 by irradiating the welded portion 62 with an energy ray such as a laser.

The second negative electrode current collector 8b to which the first negative electrode tab group 50a and the second negative electrode tab group 50b are connected is arranged on the base portion 13a of the internal insulating member 13. Further, a part of the second negative electrode current collector 8b is arranged on the first negative electrode current collector 8a. The thin portion 8d of the second negative electrode current collector 8b is welded and connected to the first negative electrode current collector 8a to form the welded portion 63. The welded portion 63 is formed at a position away from the opening 8c. It is preferable to form the welded portion 63 by irradiating the welded portion 63 with an energy ray such as a laser.

The method of connecting the first positive electrode current collector 6a and the second positive electrode current collector 6b, the connection method of the first negative electrode current collector 8a and the second negative electrode current collector 8b, the first negative electrode current collector 8a and the second negative electrode The connection method of the current collector 8b will be described as an example.

FIG. 11 is a cross-sectional view taken along the longitudinal direction of the sealing plate 2 in the vicinity of the negative electrode terminal 9. The second negative electrode current collector 8b is a current collector to which the tab connection portion 8b1 to which the negative electrode tab 50 (first negative electrode tab group 50a, second negative electrode tab group 50b) is connected and the first negative electrode current collector 8a are connected. It has a body connection portion 8b2. A step portion 8b3 is provided between the tab connection portion 8b1 and the current collector connection portion 8b2. The tab connection portion 8b1 is arranged on the base portion 13a of the internal insulating member 13. The current collector connecting portion 8b2 is arranged on the first negative electrode current collector 8a. The thin-walled portion 8d provided in the current collector connecting portion 8b2 is welded to the first negative electrode current collector 8a. When welding the first negative electrode current collector 8a and the second negative electrode current collector 8b, the opening 8c is used between the thin portion 8d of the first negative electrode current collector 8a and the second negative electrode current collector 8b. Make sure there are no gaps. Alternatively, it is confirmed that the gap generated between the thin-walled portion 8d of the first negative electrode current collector 8a and the second negative electrode current collector 8b is equal to or less than a certain value by using the opening 8c. As a result, the first negative electrode current collector 8a and the second negative electrode current collector 8b can be stably welded. It is preferable to confirm the presence or absence of a gap or the size of the gap by using the reflection of light.

It is preferable to irradiate the energy beam at a position away from the opening 8c so that the welded portion 63 is formed at a position away from the opening 8c. Compared with the case where the welded portion 63 is formed at the edge of the opening 8c, a stronger welded portion 63 can be stably formed.

The base portion 13a of the internal insulating member 13 is provided with an insulating member recess 13x. The insulating member recess 13x is arranged so as to face the back surface of the surface to which the second negative electrode current collector 8b is welded in the first negative electrode current collector 8a. As a result, it is possible to prevent the internal insulating member 13 from being damaged by the heat generated when the first negative electrode current collector 8a and the second negative electrode current collector 8b are welded.

A current collector protrusion 8x is provided in a portion of the first negative electrode current collector 8a that is not covered by the second negative electrode current collector 8b. As a result, when the first negative electrode current collector 8a is connected to the negative electrode terminal 9 and assembled to the sealing plate 2, it is possible to reliably prevent the first negative electrode current collector 8a from being assembled in the wrong direction. The current collector projection 8x preferably has an asymmetrical shape in a plan view. The current collector projection 8x preferably has a shape in a plan view having a longitudinal direction and a lateral direction. It should be noted that a plurality of current collector protrusions 8x may be provided. For example, a plurality of current collector protrusions 8x having a perfect circular shape or a square view in a plan view may be provided. The second negative electrode current collector 8b is arranged on a flat surface in the first negative electrode current collector 8a.

[Cover member]
13A and 13B are perspective views of the vicinity of the positive electrode terminal 7 after the second positive electrode current collector 6b is connected to the first positive electrode current collector 6a. In FIGS. 13A and 13B, the first positive electrode tab group 40a and the second positive electrode tab group 40b connected to the second positive electrode current collector 6b are not shown. FIG. 14 is a cross-sectional view taken along the short side of the sealing plate 2 in the vicinity of the positive electrode terminal 7 in a state where the cover member 80 is connected to the internal insulating member 11.
The resin cover member 80 is connected to the internal insulating member 11, and the cover member 80 is arranged between the first positive electrode current collector 6a and the electrode body 3. As a result, even if the electrode body 3 moves to the sealing plate 2, it is possible to prevent the electrode body 3 from coming into contact with the first positive electrode current collector 6a or the sealing plate 2. By making the cover member 80 and the internal insulating member 11 separate parts, a secondary battery that is easier to manufacture can be obtained.

The positive electrode tab 40 and the positive electrode terminal 7 can be connected by the first positive electrode current collector 6a and the second positive electrode current collector 6b. In this case, in the thickness direction of the sealing plate 2, the portion of the cover member 80 closest to the electrode body 3 becomes the electrode body 3 of the positive electrode terminal 7, the first positive electrode current collector 6a, and the second positive electrode current collector 6b. It is preferable that the electrode body 3 is arranged closer to the electrode body 3 side than the near portion.

It should be noted that the positive electrode tab 40 and the positive electrode terminal 7 can be connected only by the first positive electrode current collector without using the second positive electrode current collector. In this case, in the thickness direction of the sealing plate 2, the portion of the cover member 80 closest to the electrode body 3 is closer to the electrode body 3 than the portion of the positive electrode terminal 7 and the first positive electrode current collector that is closest to the electrode body 3. It is preferable that they are arranged in close positions.

After connecting the second positive electrode current collector 6b to the first positive electrode current collector 6a, the resin cover member 80 is connected to the internal insulating member 11. After connecting the second positive electrode current collector 6b to which the first positive electrode tab group 40a and the second positive electrode tab group 40b are connected to the first positive electrode current collector 6a, the first electrode body element 3a and the second positive electrode current collector 6b are connected. It is preferable to connect the cover member 80 to the internal insulating member 11 before assembling the second electrode body element 3b into one.

The cover member 80 has a cover portion 80a arranged so as to face the first positive electrode current collector 6a. The cover portion 80a is arranged between the first positive electrode current collector 6a and the electrode body 3. The cover portion 80a is preferably arranged so as to face the connection portion between the first positive electrode current collector 6a and the second positive electrode current collector 6b. The cover member 80 has a pair of cover connecting portions 80b extending from the cover portion 80a toward the sealing plate 2. The cover connecting portion 80b is connected to the internal insulating member 11. It is preferable that the first wall portion 11c of the internal insulating member 11 extends to the electrode body 3 side from the surface of the first positive electrode current collector 6a on the electrode body 3 side. Then, it is preferable to connect the cover connecting portion 80b to the portion of the first wall portion 11c located on the electrode body 3 side with respect to the surface of the first positive electrode current collector 6a on the electrode body 3 side. A connection opening 11e can be provided in the first wall portion 11c of the internal insulating member 11. Then, the cover connecting portion 80b has a vertical wall 80b1 extending from the cover portion 80a toward the sealing plate 2 and a connecting protrusion 80b2 provided on the side surface of the vertical wall 80b1. Then, by fitting the connecting protrusion 80b2 of the cover connecting portion 80b into the connecting opening 11e of the first wall portion 11c, the cover member 80 can be connected to the internal insulating member 11. A connection opening may be provided in the cover connection portion 80b, and a connection protrusion provided in the first wall portion 11c of the internal insulating member 11 may be fitted in the connection opening.

It is preferable that the first wall portion 11c is provided at both ends of the sealing plate 2 in the lateral insulating member 11 in the lateral insulating member 11. It is preferable that the cover connecting portions 80b are provided at both ends of the sealing plate 2 in the lateral direction in the cover member 80. Then, it is preferable to connect the facing cover connecting portion 80b and the first wall portion 11c, respectively. As a result, the internal insulating member 11 and the cover member 80 are more stably connected.

It is preferable that a gap is formed between the first positive electrode current collector 6a and the cover portion 80a in the thickness direction of the sealing plate 2. With such a configuration, the cover portion 80a can be deformed so as to bend when the electrode body 3 comes into contact with the cover portion 80a, and the impact can be mitigated. In the thickness direction of the sealing plate 2, the distance between the first positive electrode current collector 6a and the cover member 80 is preferably 1 mm or more, and more preferably 3 mm or more. It is more preferable that the cover portion 80a is provided with a root opening 80c at the root of the cover connecting portion 80b. As a result, the impact can be mitigated more effectively.

It is preferable that a gap is provided between the cover portion 80a and the positive electrode terminal 7 in the thickness direction of the sealing plate 2, and the cover portion 80a and the positive electrode terminal 7 are not in contact with each other. As a result, it is possible to effectively prevent a load from being applied to the connection portion between the positive electrode terminal 7 and the first positive electrode current collector 6a.

As shown in FIG. 15, the second positive electrode current collector 6b has a tab connection portion 6b1 to which the positive electrode tab 40 is connected and a current collector connection portion 6b2 to which the first positive electrode current collector 6a is connected. A step portion 6b3 is provided between the tab connection portion 6b1 and the current collector connection portion 6b2. In the thickness direction of the sealing plate 2, the distance between the sealing plate 2 and the current collector connecting portion 6b2 is larger than the distance between the sealing plate 2 and the tab connecting portion 6b1. In the thickness direction of the sealing plate 2, the cover portion 80a is preferably located closer to the electrode body 3 than the current collector connecting portion 6b2. This results in a secondary battery having a higher volumetric energy density and being easier to manufacture. The positive electrode terminal 7 has a flange portion 7a, an insertion portion 7b, and a caulking portion 7c. The inner insulating member 11 is provided with an insulating member recess 11x.

The cover portion 80a is provided with a support portion 80d that projects from the cover portion 80a toward the first positive electrode current collector 6a. The support portion 80d is preferably arranged between the pair of cover connection portions 80b. A plurality of support portions 80d may be provided. It is preferable that the tip of the support portion 80d is in contact with the first positive electrode current collector 6a. Alternatively, a small gap may be formed between the tip of the support portion 80d and the first positive electrode current collector 6a. For example, the gap formed between the tip of the support portion 80d and the first positive electrode current collector 6a (the distance between the tip of the support portion 80d and the first positive electrode current collector 6a in the thickness direction of the sealing plate 2) is It is preferably 3 mm or less, preferably 1 mm or less, and more preferably 0.5 mm or less. When the cover portion 80a is bent, the tip of the support portion 80d can be brought into contact with the first positive electrode current collector 6a. Since the support portion 80d is formed, it is possible to prevent the cover member 80 from being damaged.

The cover portion 80a may be provided with a wall-shaped portion extending in the longitudinal direction of the sealing plate 2, a wall-shaped portion extending in the lateral direction of the sealing plate 2, a columnar portion, or the like, and these may be used as the supporting portion 80d. can.

In the thickness direction of the sealing plate 2, the surface of the cover portion 80a on the electrode body 3 side is closer to the electrode body 3 than the portion of the first positive electrode current collector 6a and the second positive electrode current collector 6b that is closest to the electrode body 3. It is preferable to arrange it on the side. As a result, even if the electrode body 3 moves to the sealing plate 2, the electrode body 3 first contacts the cover portion 80a, so that the electrode body 3 comes into contact with the first positive electrode current collector 6a and the second positive electrode collection. Contact with the electric body 6b can be suppressed.

The first positive electrode current collector 6a preferably has a current collector projection 6x on the surface on the electrode body 3 side. The end of the current collector protrusion 6x on the electrode body 3 side is arranged closer to the electrode body 3 than the end of the positive electrode terminal 7 on the electrode body 3 side, and the current collector protrusion 6x is the cover portion 80a. It is preferable to face each other. As a result, even when the electrode body 3 is in contact with the cover portion 80a, it is possible to effectively suppress the load from being applied to the connection portion between the positive electrode terminal 7 and the first positive electrode current collector 6a.

The cover member 80 may be arranged on at least one of the first positive electrode current collector 6a side and the first negative electrode current collector 8a side. The cover member 80 may be arranged between the first positive electrode current collector 6a and the electrode body 3, and the cover member may not be arranged between the first negative electrode current collector 8a and the electrode body 3.

The internal insulating member 11 has a liquid injection opening 11f at a position facing the electrolytic liquid injection hole 15 provided in the sealing plate 2. A cylindrical portion 11g extending toward the electrode body 3 is provided around the liquid injection opening 11f. In the thickness direction of the sealing plate 2, the cover portion 80a is preferably located closer to the electrode body 3 than the end portion of the tubular portion 11g on the electrode body 3 side. As a result, when the electrode body 3 moves to the sealing plate 2 side, it comes into contact with the surface of the cover portion 80a on the electrode body 3 side before the tubular portion 11g, so that a load is locally applied to the electrode body 3. Can be suppressed.

[Preparation of electrode body]
The first positive electrode tab group 40a, the second positive electrode tab group 40b, and the second positive electrode tab group 40b so that the upper surface of the first electrode body element 3a and the upper surface of the second electrode body element 3b in FIG. 10 are in direct contact with each other via other members. The 1 negative electrode tab group 50a and the 2nd negative electrode tab group 50b are curved. As a result, the first electrode body element 3a and the second electrode body element 3b are combined into one electrode body 3. It is preferable that the first electrode body element 3a and the second electrode body element 3b are put together by tape or the like. Alternatively, it is preferable that the first electrode body element 3a and the second electrode body element 3b are arranged in a box-shaped or bag-shaped electrode body holder 14 and put together.

The outer surface of the curved first positive electrode tab group 40a faces the inner surface of one of the pair of second wall portions 11b, and the outer surface of the curved second positive electrode tab group 40b faces the inner surface of one of the pair of second wall portions 11b. It is preferable to face the other inner surface. The outer surface of the curved first negative electrode tab group 50a faces the inner surface of one of the pair of third wall portions 13b, and the outer surface of the curved second negative electrode tab group 50b faces the inner surface of one of the pair of third wall portions 13b. It is preferable to face the other inner surface of the.

The electrode body 3 wrapped in the electrode body holder 14 made of a resin sheet formed into a box shape or a bag shape is inserted into the square exterior body 1. Then, the sealing plate 2 and the square exterior body 1 are welded, and the opening of the square exterior body 1 is sealed by the sealing plate 2. Then, the electrolytic solution is injected into the square exterior body 1 through the electrolytic solution injection hole 15 provided in the sealing plate 2. After that, the electrolytic solution injection hole 15 is sealed with a sealing member such as a blind rivet.

When viewed from a direction perpendicular to the side wall having a larger area of the square exterior body 1, the electrode body holder 14 and the second wall portion 11b overlap each other, and the electrode body holder 14 and the third wall portion 13b overlap each other. Is preferable. This makes it possible to more reliably prevent the first positive electrode tab group 40a, the second positive electrode tab group 40b, the first negative electrode tab group 50a, or the second negative electrode tab group 50b from coming into contact with the square exterior body 1.

In the square secondary battery 20 according to the above-described embodiment, the positive electrode tab group (first positive electrode tab group 40a, second positive electrode tab group 40b) and the negative electrode tab group (first positive electrode tab group 40b) are located at the end of the electrode body 3 on the sealing plate 2 side. The negative electrode tab group 50a and the second negative electrode tab group 50b) are arranged respectively. The positive electrode tab group is connected to the surface of the second positive electrode current collector 6b arranged along the sealing plate 2 in a curved state on the electrode body 3 side. Further, the negative electrode tab group is connected to the surface of the second negative electrode current collector 8b arranged along the sealing plate 2 in a curved state on the electrode body 3 side. With such a configuration, the secondary battery has a higher volumetric energy density.

<Others>
In the above-described embodiment, an example in which the electrode body 3 is composed of two electrode body elements is shown, but the present invention is not limited thereto. The electrode body 3 may be composed of three or more electrode body elements. The electrode body element is not limited to the laminated electrode body, and may be a wound type electrode body in which a band-shaped positive electrode plate and a band-shaped negative electrode plate are wound via a band-shaped separator. Further, the electrode body 3 may be one laminated electrode body. Further, the electrode body 3 may be one winding type electrode body in which a band-shaped positive electrode plate and a band-shaped negative electrode plate are wound via a band-shaped separator.

The cover member 80 is preferably made of resin. For example, it is preferably made of polypropylene (PP), polyethylene (PE), polyphenylene sulfide (PPS), or the like.

As the energy ray used for welding, a laser, an electron beam, or the like can be used.

In the square secondary battery 20 according to the above-described embodiment, an example is shown in which the positive electrode collector that electrically connects the positive electrode terminal and the positive electrode tab is composed of two parts, but the positive electrode current collector is used as one component. May be good. In the square secondary battery 20 according to the above-described embodiment, an example is shown in which the negative electrode current collector that electrically connects the negative electrode terminal and the negative electrode tab is composed of two parts, but the negative electrode current collector is used as one component. May be good. Further, a current cutoff mechanism may be provided in the conductive path between the positive electrode terminal and the positive electrode plate or the conductive path between the negative electrode terminal and the negative electrode plate.

Known materials can be used for the positive electrode plate, the negative electrode plate, the separator, the electrolyte and the like. The battery system of the secondary battery of the present invention is not limited. For example, it can be a non-aqueous electrolyte secondary battery such as a lithium ion battery. Further, the shape of the secondary battery of the present invention is not limited to a specific shape.

20 ... Square secondary battery 1 ... Square exterior body 2 ... Seal plate 2a ... Positive electrode terminal insertion hole
2b ... Negative electrode terminal insertion hole 2c ... Circular protrusion 100 ... Battery case 3 ... Electrode body 3a ... First electrode body element 3b ... Second electrode body element 4 ... Positive electrode plate 4a ... Positive electrode core 4b ... Positive electrode active material mixture layer 4d ... Positive electrode protective layer 40 ... Positive electrode tab 40a ... First positive electrode tab group 40b ... Second positive electrode tab group 5 ... Negative electrode plate 5a ... Negative electrode core 5b ... Negative electrode active material mixture layer 50 ... Negative electrode tab 50a ... First negative electrode tab group 50b ... Second negative electrode tab group 6a ...・ First positive electrode current collector 6x ・ ・ ・ Current collector protrusion 6b ・ ・ ・ Second positive electrode current collector 6b1 ・ ・ ・ Tab connection part 6b2 ・ ・ ・ Current collector connection part 6b3 ・ ・ ・ Step part 6c ・ ・・ Opening 6d ・ ・ ・ Thin-walled part 6e ・ ・ ・ Current collector opening 7 ・ ・ ・ Positive electrode terminal 7a ・ ・ ・ Flange part 7b ・ ・ ・ Insertion part 7c ・ ・ ・ Caulking part 8a ・ ・ ・ First negative electrode current collection Body 8x ・ ・ ・ Current collector protrusion 8y ・ ・ ・ Terminal connection hole 8z ・ ・ ・ Tapered part 8b ・ ・ ・ Second negative electrode current collector 8b1 ・ ・ ・ Tab connection part 8b2 ・ ・ ・ Current collector connection part 8b3 ・・ ・ Step part 8c ・ ・ ・ Opening part 8d ・ ・ ・ Thin wall part 9 ・ ・ ・ Negative electrode terminal 9a ・ ・ ・ Flange part 9b ・ ・ ・ Insertion part 9c ・ ・ ・ Caulking part 9d ・ ・ ・ Tip concave part 9x ・ ・ ・1st metal part 9y ・ ・ ・ 2nd metal part 95 ・ ・ ・ Gap 70 ・ ・ ・ Coagulation part 70a ・ ・ ・ Recessed part 10 ・ ・ ・ External side insulating member 11 ・ ・ ・ Internal side insulating member 11a ・ ・ ・ Base part 11b ... 2nd wall part 11c ... 1st wall part 11d ... Outer peripheral rib 11e ... Connection opening 11f ... Liquid injection opening 11g ... Cylindrical part 11x ... Insulation member recess 12 ... External insulation member 13 ... Internal insulation member 13a ... Base 13b ... Third wall 13c ... Outer rib 13x ... Insulation member recess 14 ... Electrode holder 15 ... Electrodeole injection hole 16 ... Sealing member 17 ... Gas discharge valve 60, 61, 62, 63 ... Welding part 80 ... Cover member 80a ... Cover part 80b ...・ Cover connection part 80b1 ・ ・ ・ Vertical wall 80b2 ・ ・ ・ Connection protrusion 80c ・ ・ ・ Root opening 80d ・ ・ ・ Support part

Claims (4)

An electrode body including a positive electrode plate and a negative electrode plate,
An exterior body having an opening and accommodating the electrode body,
A sealing plate having a terminal insertion hole and sealing the opening,
A terminal that penetrates the terminal insertion hole and
A current collector having a terminal connection hole and electrically connected to the positive electrode plate or the negative electrode plate,
It is a secondary battery with
The terminal is arranged in the terminal connection hole and
The terminal connection hole has a first hole portion and a second hole portion connected to the first hole portion.
The first hole portion is provided on the electrode body side from the second hole portion.
The inner dimension of the first hole portion is larger than the inner dimension of the second hole portion.
The terminal has a caulked portion having an outer diameter larger than the inner diameter of the portion having the smallest inner diameter in the terminal connection hole.
The crimped portion and the current collector are joined by a solidified portion in which at least one of the crimped portion and the current collector is melted and solidified.
A recess is formed in the solidified portion, and a recess is formed in the solidified portion.
A secondary battery in which the bottom of the recess is located closer to the electrode body than the second hole in the thickness direction of the current collector. The secondary battery according to claim 1, wherein the terminal connection hole has a tapered portion whose inner diameter gradually increases toward a direction away from the sealing plate. The secondary battery according to claim 1 or 2, wherein at least a part of the caulked portion projects toward the electrode body side from the surface of the current collector on the electrode body side. The thickness of the portion of the solidified portion located at the bottom of the recess in the thickness direction of the current collector is larger than the thickness of the portion of the solidified portion located on the side wall of the recess in the radial direction of the terminal connection hole. The secondary battery according to any one of claims 1 to 3.

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