JP7265710B2 - SECONDARY BATTERY AND METHOD FOR MANUFACTURING SECONDARY BATTERY - Google Patents

Description

TECHNICAL FIELD The present invention relates to a secondary battery such as a lithium ion battery and a method for manufacturing the secondary battery.

Conventionally, as this type of secondary battery, for example, the one disclosed in Patent Document 1 is known. In such a secondary battery, a battery core as a power generation element is placed on a rectangular laminate film as an exterior member, and a rectangular plate-shaped positive electrode terminal and a negative electrode extend side by side so as to form a pair from the battery core and the battery core. The laminate film is folded in half so as to wrap around the base ends of the terminals, and the peripheral edge portions of the laminate film are welded together.

In this case, portions other than the base end portions of the positive electrode terminal and the negative electrode terminal protrude from between the peripheral edge portions of the laminated films that are folded and welded. For this reason, the peripheral edge portions of the laminate film where the positive electrode terminal and the negative electrode terminal protrude are usually welded while being stretched along the contours of the positive electrode terminal and the negative electrode terminal using a jig, thereby ensuring the sealability.

Such a method can ensure the sealability of the peripheral edge portion of the laminate film where the positive electrode terminal and the negative electrode terminal protrude only when the thickness of the positive electrode terminal and the negative electrode terminal is about 0.5 mm or less. This is because if the thickness of the positive electrode terminal and the negative electrode terminal is, for example, several millimeters, the laminate film may be torn when the laminate film is stretched along the contours of the positive electrode terminal and the negative electrode terminal.

Japanese Patent Application Laid-Open No. 2001-102090

However, in order to increase the output of the secondary battery as described above, it is necessary to increase the thickness of each of the positive electrode terminal and the negative electrode terminal to, for example, several millimeters. There is a problem that it becomes impossible to ensure the sealability of the peripheral portion of the laminate film.

The present invention has been made by paying attention to such problems existing in the prior art. It is an object of the present invention to provide a secondary battery and a method for manufacturing the secondary battery that can ensure the sealing performance of the outer package regardless of the thickness of the electrode tabs.

Means for solving the above problems and their effects will be described below.
A secondary battery that solves the above problems includes an electrode laminate in which a plurality of electrode plates are laminated, an electrode tab joined to the electrode laminate, and the electrode laminate and the electrode tab folded in a folded manner. a flexible sheet-like exterior body with a peripheral edge sealed in a loose state, wherein a part of the electrode tab protrudes outside from the exterior body. An insertion portion through which a part of the electrode tab is inserted is formed in the folded portion of the exterior body, and the electrode tab includes a thick portion located in the exterior body and a thick portion adjacent to the thick portion. and a thin portion that is thinner than the thick portion, the thin portion protruding from the insertion portion to the outside of the exterior body, and the thick portion and the thin portion of the electrode tab The gist is that an insertion peripheral portion, which is a portion of the exterior body surrounding the insertion portion, is welded to the stepped surface of.

According to this configuration, since the insertion peripheral portion, which is the portion surrounding the insertion portion of the exterior body, is welded to the stepped surface between the thick portion and the thin portion of the electrode tab, the exterior body can be secured regardless of the thickness of the electrode tab. It is possible to ensure the sealing performance of the body.

A method for manufacturing a secondary battery that solves the above problems includes an electrode laminate in which a plurality of electrode plates are laminated, an electrode tab joined to the electrode laminate, and the electrode laminate and the electrode tab folded back. a flexible sheet-like outer body with a peripheral edge sealed in a wrapped state, wherein a part of the electrode tab is configured to protrude outside from the outer body A method of manufacturing a battery, comprising: forming an insertion portion in the exterior body; and forming a thick portion in an intermediate portion and forming a narrow portion adjacent to the thick portion and narrower than the thick portion at a tip portion. inserting the thin portion of the electrode tab provided in the electrode tab into the insertion portion so as to bring the thick portion into contact with an insertion peripheral portion surrounding the insertion portion of the exterior body; is folded back at the insertion peripheral edge portion, and the electrode laminate and the portion of the electrode tab on the base end side from the thick portion are wrapped by the exterior body, and the thick portion and the narrow portion of the electrode tab are wrapped. and welding and sealing the peripheral edge of the exterior body.

According to this configuration, since the insertion peripheral portion, which is the portion surrounding the insertion portion of the exterior body, is welded to the stepped surface between the thick portion and the thin portion of the electrode tab, the exterior body can be welded regardless of the thickness of the electrode tab. can ensure the sealing performance.

1 is a perspective view of a secondary battery in one embodiment; FIG. The top view of a secondary battery. FIG. 3 is a perspective view of an electrode laminate to which electrode tabs are joined; The top view of an exterior body. FIG. 4 is a perspective view showing an electrode laminate and an exterior body to which electrode tabs are joined; FIG. 4 is a perspective view showing a state in which the electrode laminate to which the electrode tabs are joined is covered with an exterior body. The perspective view which shows the electrode laminated body and exterior body which the electrode tab was joined in the example of a change.

An embodiment of a secondary battery will be described below with reference to the drawings.
As shown in FIGS. 1 and 2, the secondary battery 11 is composed of, for example, a lithium ion battery, and includes a flexible rectangular sheet-like exterior body 12 and a sealed body 12 so as to be wrapped in the exterior body 12 . It has an electrode laminate 13 and an electrolytic solution (not shown) which are stopped, and a pair of electrode tabs 14 partially protruding from the exterior body 12 to the outside.

The electrode laminate 13 is a strip-shaped separator formed by zigzag-folding a rectangular positive electrode plate 15 as an example of an electrode plate and a rectangular negative electrode plate 16 as an example of an electrode plate and alternately repeating mountain folds and valley folds. It is formed by alternately stacking a plurality of layers via 17 . In this case, the positive electrode plate 15 is sandwiched between the opposing surfaces on one side of the separator 17, and the negative electrode plate 16 is sandwiched between the opposing surfaces on the other side.

Some of the plurality of positive electrode plates 15 are laminated and joined so as to be electrically connected to each other in a state of protruding so as to be exposed from one end of the separator 17 , and some of the plurality of negative electrode plates 16 are attached to the separator 17 . They are stacked and joined so as to be electrically connected to each other while protruding so as to be exposed from the other end side. The portion of the plurality of stacked positive electrode plates 15 exposed from the separator 17 and the portion of the plurality of stacked negative electrode plates 16 exposed from the separator 17 were provided with metal electrode tabs 14 having a square prism shape from the center portion to the base end. The parts are joined so that the parts are electrically connected to each other.

A thick portion 18 that is thicker than other portions of each electrode tab 14 is provided at a position closer to the tip than the central portion of each electrode tab 14 . In this case, the thick portion 18 is provided on the electrode tab 14 by welding a square frame-shaped synthetic resin component forming the thick portion 18 . In other words, the electrode tab 14 and the thick portion 18 are separated. A portion of each electrode tab 14 on the distal end side of the thick portion 18 is formed as a thin portion 19 adjacent to the thick portion 18 and thinner than the thick portion 18 . Therefore, a stepped surface 20 is formed between the thick portion 18 and the narrow portion 19 of each electrode tab 14 .

The exterior body 12 is composed of, for example, a flexible laminate film having a three-layer structure in which an aluminum foil is sandwiched between a pair of synthetic resin sheets. The exterior body 12 is folded in two to wrap the electrode laminate 13 and the pair of electrode tabs 14 and is formed into a bag shape by sealing the periphery by welding. A pair of insertion portions 22 are formed in the folded portion 21 of the exterior body 12 so as to correspond to the narrow portions 19 of the pair of electrode tabs 14 . The inserting portion 22 is formed to have a size that allows the thin portion 19 of the electrode tab 14 to pass therethrough but does not allow the thick portion 18 of the electrode tab 14 to pass therethrough. As shown in FIG. 4, the insertion portion 22 of the present embodiment is configured by a cut formed in the exterior body 12 by, for example, a cutting tool.

As shown in FIGS. 1 and 2 , the thin portions 19 of the pair of electrode tabs 14 are inserted into the pair of insertion portions 22 and protrude from the insertion portions 22 to the outside of the exterior body 12 . Since the thick portions 18 of the pair of electrode tabs 14 are not inserted into the pair of insertion portions 22 , they are positioned inside the exterior body 12 .

As shown in FIGS. 2 and 4, portions surrounding the pair of insertion portions 22 in the outer package 12 and corresponding to the stepped surfaces 20 between the thick portion 18 and the thin portion 19 of the pair of electrode tabs 14 are formed. The area of , is the insertion peripheral edge portion 23 . A peripheral edge portion 23 of the outer package 12 is welded to the step surface 20 between the thick portion 18 and the thin portion 19 of the pair of electrode tabs 14 .

Next, a method for manufacturing the secondary battery 11 will be described.
When manufacturing the secondary battery 11, first, as shown in FIG. Join. Subsequently, a square frame-shaped synthetic resin component forming the thick portion 18 is temporarily fitted to the intermediate portion (portion between the tip portion and the central portion) of each electrode tab 14 . Subsequently, as shown in FIG. 4 , cuts are made at positions corresponding to the respective electrode tabs 14 in the folded portion 21 of the exterior body 12 to form insertion portions 22 respectively.

Subsequently, as shown in FIGS. 5 and 6, the thin portions 19 of the two electrode tabs 14 are inserted into the two insertion portions 22 of the outer casing 12, respectively, and the thick portions 18 of the two electrode tabs 14 are inserted. The step surface 20 between the (square frame-shaped synthetic resin part) and the thin portion 19 is brought into contact with the two insertion peripheral edge portions 23 of the exterior body 12 . Subsequently, the outer casing 12 is folded back at the two insertion peripheral edge portions 23 positioned at the folded portion 21, and the outer casing 12 wraps the electrode laminate 13 and the two electrode tabs 14 from the thick portion 18 to the base end side. .

Subsequently, the two insertion peripheral edge portions 23 of the exterior body 12 are heated and welded to the stepped surfaces 20 between the thick portion 18 and the thin portion 19 of the two electrode tabs 14, and at the same time, the two thick portions 18 ( A rectangular frame-shaped synthetic resin part) is heated and welded to the two electrode tabs 14 respectively. In this case, the insertion peripheral portion 23 and the thick portion 18 (square frame-shaped synthetic resin component) are simultaneously heated by an electric heating tool such as a soldering iron.

Subsequently, the periphery of the exterior body 12 is welded and sealed. At this time, an unwelded portion is left in a part of the peripheral edge of the exterior body 12, and after injecting an electrolytic solution (not shown) into the exterior body 12 from the unwelded portion, the welding is performed. Weld the missing parts. Thereby, the secondary battery 11 shown in FIG. 1 is completed.

According to the embodiment detailed above, the following effects are exhibited.
(1) In the secondary battery 11 , an inserting portion 22 through which a portion of the electrode tab 14 is inserted is formed in the folded portion 21 of the exterior body 12 , and the electrode tab 14 is positioned inside the exterior body 12 . and a thin portion 19 narrower than the thick portion 18 adjacent to the thick portion 18 . A peripheral edge portion 23 through which the exterior body 12 is inserted is welded to the stepped surface 20 between the thick portion 18 and the thin portion 19 of the electrode tab 14 . According to this configuration, since the insertion peripheral edge portion 23 located at the folded portion 21 of the outer package 12 is welded to the stepped surface 20 between the thick portion 18 and the thin portion 19 of the electrode tab 14 , the electrode tab 14 is The sealing performance of the exterior body 12 can be ensured regardless of the thickness.

(2) In the secondary battery 11 , the insertion portion 22 is configured by a cut formed in the exterior body 12 . Normally, if the insertion portion 22 is configured by a through hole, scraps having the same shape as the through hole are produced when the insertion portion is formed in the exterior body 12 . In this respect, according to this configuration, since the insertion portion 22 is formed by a cut, even if the insertion portion 22 is formed in the exterior body 12, it is possible to prevent waste from being generated. In other words, the insertion portion 22 can be formed in the exterior body 12 without producing waste.

(3) The manufacturing method of the secondary battery 11 includes forming the insertion portion 22 in the outer package 12, and having the thick portion 18 in the middle portion and being adjacent to the thick portion 18 and thinner than the thick portion 18. The thin portion 19 of the electrode tab 14 having the thin portion 19 at the tip is inserted into the insertion portion 22 to bring the thick portion 18 into contact with the insertion peripheral portion 23 located at the folded portion 21 of the exterior body 12 . , the outer package 12 is folded back at the insertion peripheral edge portion 23 , and the electrode laminate 13 and the portion of the electrode tab 14 on the proximal end side from the thick portion 18 are wrapped by the outer package 12 , and the thick portion of the electrode tab 14 welding the insertion peripheral edge portion 23 to the stepped surface 20 between 18 and the narrow portion 19; and sealing the peripheral edge portion of the exterior body 12 by welding. According to this configuration, the insertion peripheral edge portion 23 of the outer package 12 is welded to the stepped surface 20 between the thick portion 18 and the thin portion 19 of the electrode tab 14 , so that regardless of the thickness of the electrode tab 14 , the outer package can be 12 sealability can be ensured.

(4) In the manufacturing method of the secondary battery 11, when the electrode tab 14 and the thick portion 18 are separate bodies as in the above embodiment, the thick portion 18 and the thin portion 19 of the electrode tab 14 The electrode tab 14 and the thick portion 18 are welded at the same time as the insertion peripheral portion 23 is welded to the stepped surface 20 of . According to this configuration, welding between the stepped surface 20 of the thick portion 18 and thin portion 19 of the electrode tab 14 and the insertion peripheral portion 23 and welding between the electrode tab 14 and the thick portion 18 are performed simultaneously. Therefore, the secondary battery 11 can be manufactured efficiently.

(Change example)
The above embodiment can be implemented with the following modifications. Moreover, the above embodiments and the following modified examples can be implemented in combination with each other within a technically consistent range.

- As shown in FIG. 7, the electrode tab 14 may be cylindrical and the thick portion 18 may be circular frame-shaped. In this case, the insertion portion 22 of the exterior body 12 is preferably formed by radial cuts.

- You may comprise the insertion part 22 with a through-hole.
- The thick portion 18 may be formed integrally with the electrode tab 14 . In this case, in the manufacturing method of the secondary battery 11 of the above embodiment, the step of heating the two thick portions 18 (square frame-shaped synthetic resin parts) and welding them to the two electrode tabs 14 respectively is omitted. Furthermore, in this case, the electrode tab 14 including the thick portion 18 may be entirely made of metal.

The thick portion 18 may be provided on the electrode tab 14 by insert-molding a square frame-shaped synthetic resin component in advance, or may be provided on the electrode tab 14 by tightly fitting a square frame-shaped synthetic resin component in advance. may be set to

- The secondary battery 11 may be a secondary battery other than a lithium ion battery.

DESCRIPTION OF SYMBOLS 11... Secondary battery 12... Exterior body 13... Electrode laminated body 14... Electrode tab 15... Positive electrode plate as an example of an electrode plate 16... Negative plate as an example of an electrode plate 18... Thick part 19... Narrow part 20... Step surface 21... Folded part 22... Insertion part 23... Insertion peripheral part

Claims (4)

an electrode laminate in which a plurality of electrode plates are laminated;
an electrode tab joined to the electrode laminate;
a flexible sheet-like exterior body in which the electrode laminate and the electrode tabs are wrapped in a folded state and whose peripheral edge is sealed;
with
A secondary battery configured such that a portion of the electrode tab protrudes outward from the exterior body,
An insertion portion through which a part of the electrode tab is inserted is formed in the folded portion of the exterior body,
The electrode tab has a thick portion positioned within the outer package and a thin portion adjacent to the thick portion and narrower than the thick portion,
The thin portion protrudes from the insertion portion to the outside of the exterior body,
A secondary battery according to claim 1, wherein a peripheral insertion edge portion of the exterior body, which is a portion surrounding the insertion portion, is welded to a stepped surface between the thick portion and the thin portion of the electrode tab. 2. The secondary battery according to claim 1, wherein the insertion portion is formed by a cut formed in the exterior body. an electrode laminate in which a plurality of electrode plates are laminated;
an electrode tab joined to the electrode laminate;
a flexible sheet-like exterior body in which the electrode laminate and the electrode tabs are wrapped in a folded state and whose peripheral edge is sealed;
with
A method for manufacturing a secondary battery in which a part of the electrode tab protrudes outward from the exterior body,
forming an insertion portion in the exterior body;
The thin portion of the electrode tab having a thick portion in the middle portion and a narrow portion adjacent to the thick portion and narrower than the thick portion at the distal end portion is inserted into the insertion portion. bringing the thick portion into contact with an insertion peripheral edge portion that is a portion surrounding the insertion portion of the exterior body;
folding back the outer package at the insertion peripheral edge portion, and wrapping the electrode laminate and the electrode tab from the thick portion to the base end side with the outer package;
welding the insertion peripheral portion to a stepped surface between the thick portion and the thin portion of the electrode tab;
fusing and sealing the periphery of the exterior body;
A method for manufacturing a secondary battery, comprising: When the electrode tab and the thick portion are separate members, the insertion peripheral portion is welded to the stepped surface between the thick portion and the thin portion of the electrode tab, and the electrode tab is welded at the same time. 4. The method of manufacturing a secondary battery according to claim 3, wherein the thick portion is welded to the thick portion.

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