JP6715039B2 - Electrochemical cell and method of manufacturing electrochemical cell - Google Patents

Description

The present invention relates to an electrochemical cell and a method for manufacturing an electrochemical cell.

Electrochemical cells such as non-aqueous electrolyte secondary batteries and electric double layer capacitors have a structure in which an electrode body is provided inside an outer container. The electrode body is formed by alternately stacking the positive electrode body and the negative electrode body with the separator interposed therebetween. In addition, a tab is connected to each of the positive electrode body and the negative electrode body. For example, the electrochemical cell described in Patent Document 1 is provided with an electrode body in which a positive electrode plate (positive electrode body) and a negative electrode plate (negative electrode body) are arranged to face each other with a separator interposed therebetween and are wound in this state. There is. Further, in the electrochemical cell described in Patent Document 1, a pair of tabs extends from the end surface of the wound electrode body. In this case, the tab is attached by welding or the like to each of the positive electrode body and the negative electrode body in which at least a part thereof is expanded, and then the tab is wound together with the positive electrode body and the negative electrode body.

JP, 2005-243524, A

However, when the tab is extended from the end face of the wound electrode body, the position of the tab may be changed from the desired position due to the change in tension applied during the winding of the positive electrode body and the negative electrode body and the tolerance of the electrode length. There is a possibility that the distance between the pair of tabs deviates from the design value. Particularly in a miniaturized electrochemical cell, when the tab is the outermost circumference, the position of the tab changes due to a slight change in the tension when the positive electrode body and the negative electrode body are wound or the tolerance of the electrode length. The tab spacing easily deviates from the design value. Therefore, there is a problem in that it is difficult to place the tab at a desired position with respect to the outer container, which makes it difficult to manufacture the electrochemical cell.

Therefore, the present invention provides an electrochemical cell that is easily manufactured and a method for manufacturing the electrochemical cell.

The electrochemical cell of the present invention has a base formed in a concave shape, and includes an outer container having a pair of current collecting pads formed on the inner bottom surface of the base, and an electrode body housed in the outer container. The electrode body includes a positive electrode body having a positive electrode current collector and a negative electrode body having a negative electrode current collector, which are laminated with a separator interposed therebetween, and an electrode body main body part wound around a winding axis. From the edge of the positive electrode current collector in the outermost periphery of the positive electrode body, extending along the direction orthogonal to the axial direction of the winding axis, and a positive electrode tab connected to one of the current collecting pads, From the edge of the negative electrode current collector in the outermost peripheral portion of the negative electrode body, extending along the direction orthogonal to the axial direction, a negative electrode tab connected to the other current collecting pad, It is a feature.

In the present invention, the positive electrode tab extends from the edge of the positive electrode current collector in the outermost peripheral portion of the positive electrode body along the direction orthogonal to the axial direction, and the negative electrode tab of the negative electrode current collector in the outermost peripheral portion of the negative electrode body. It extends from the edge along the direction orthogonal to the axial direction. Therefore, the relative position between the edge of the positive electrode current collector at the outermost peripheral portion of the positive electrode body and the edge of the negative electrode current collector at the outermost peripheral portion of the negative electrode body is determined by the change in tension during winding or the electrode length. It is possible to prevent the relative positions of the positive electrode tab and the negative electrode tab from being displaced in the axial direction even when the relative positions deviate from the desired relative positions in the direction orthogonal to the axial direction. With this, it is possible to prevent the distance between the positive electrode tab and the negative electrode tab from deviating from the designed value, so that the positive electrode tab and the negative electrode tab can be accurately positioned with respect to the pair of current collecting pads of the outer container. Therefore, an electrochemical cell that can be easily manufactured can be provided.

In the above electrochemical cell, it is preferable that the positive electrode tab is integrally formed with the positive electrode current collector, and the negative electrode tab is integrally formed with the negative electrode current collector.

According to the present invention, it is not necessary to use a tab that is a separate member from the current collector, so that the step of connecting the current collector and the tab can be omitted. Therefore, an electrochemical cell that can be easily manufactured can be provided.
Moreover, according to the present invention, it is not necessary to use a tab that is a member separate from the current collector, so that the number of parts can be reduced. Also, when using a tab that is a separate member from the current collector, a minute projection or the like may be formed at the connection between the current collector and the tab due to welding, etc. It is necessary to cover the part with insulating tape to protect the separator. On the other hand, in the present invention, since the tab is formed integrally with the current collector, it is not necessary to attach an insulating tape. Therefore, the number of parts can be reduced. Therefore, a low-cost electrochemical cell can be provided.

In the above electrochemical cell, it is preferable that the positive electrode body is formed in a smaller area than the negative electrode body, and the separator covers the positive electrode body.

According to the present invention, contact between the positive electrode body and the negative electrode body can be prevented by the separator having the minimum area. Therefore, a low-cost electrochemical cell can be provided.

The method for producing an electrochemical cell of the present invention is the method for producing an electrochemical cell described above, wherein a winding step of winding the positive electrode body and the negative electrode body in a laminated state through the separator, After performing the winding step, at least one of the positive electrode tab and the negative electrode tab is cut to adjust the length thereof , and a tab adjusting step of aligning the positions of the positive electrode tab and the negative electrode tab. , Are provided.

According to the present invention, even when the relative position of the positive electrode tab and the negative electrode tab in the direction orthogonal to the axial direction in the winding step deviates from the desired relative position, and the positions of the tip portions of the positive electrode tab and the negative electrode tab become uneven. By adjusting the lengths of the positive electrode tab and the negative electrode tab in the tab adjusting step, the positions of the tip portions of the positive electrode tab and the negative electrode tab can be aligned. This makes it possible to accurately position the positive electrode tab and the negative electrode tab with respect to the pair of current collecting pads of the outer container. Therefore, the electrochemical cell can be easily manufactured.

According to the present invention, the relative position between the edge of the positive electrode current collector at the outermost peripheral portion of the positive electrode body and the edge of the negative electrode current collector at the outermost peripheral portion of the negative electrode body is a change in tension during winding. Even when the positive electrode tab and the negative electrode tab are displaced from the desired relative position in the direction orthogonal to the axial direction due to the tolerance of the electrode length or the electrode length, the axial relative positions of the positive electrode tab and the negative electrode tab can be prevented from being displaced. With this, it is possible to prevent the distance between the positive electrode tab and the negative electrode tab from deviating from the designed value, so that the positive electrode tab and the negative electrode tab can be accurately positioned with respect to the pair of current collecting pads of the outer container. Therefore, an electrochemical cell that can be easily manufactured can be provided.

It is a perspective view of the battery of an embodiment. FIG. 2 is a partial cross-sectional view taken along the line II-II in FIG. 1. It is a perspective view of the electrode body of an embodiment. It is a top view in the expanded state of the electrode body of an embodiment. It is an exploded perspective view of the electrode body of an embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, a lithium ion secondary battery (hereinafter, simply referred to as “battery”), which is a type of non-aqueous electrolyte secondary battery, will be described as an example of the electrochemical cell.

FIG. 1 is a perspective view of the battery of the embodiment. FIG. 2 is a partial cross-sectional view taken along the line II-II of FIG.
As shown in FIGS. 1 and 2, the battery 1 includes an outer container 2, and an electrode body 10 housed in the outer container 2 together with a nonaqueous electrolyte such as an electrolytic solution.

The outer container 2 includes a base 3 formed in a concave shape, a seal ring 4 provided on an open end surface of the base 3, a lid 5 that is superposed on the seal ring 4, and hermetically seals the inside of the base 3. Is equipped with. On the inner bottom surface of the base 3, a pair of current collecting pads 6 are arranged in parallel in accordance with the positions of a positive electrode tab 21 and a negative electrode tab 22 described later. Each current collection pad 6 is connected to each of a pair of external electrodes 8 formed on the outer surface of the base 3 via each of a pair of connection electrodes 7 filled in a through hole penetrating the bottom of the base 3. There is.

FIG. 3 is a perspective view of the electrode body of the embodiment. FIG. 4 is a plan view of the electrode body of the embodiment in a developed state. FIG. 5 is an exploded perspective view of the electrode body of the embodiment.
As shown in FIGS. 3 to 5, the electrode body 10 is formed in a columnar shape. The electrode body 10 includes an electrode body main body portion 11, a positive electrode tab 21, and a negative electrode tab 22. The electrode body main body portion 11 includes a positive electrode body 12, a negative electrode body 13, and a separator 14, and is wound around the winding axis P in a state where the positive electrode body 12 and the negative electrode body 13 are laminated with the separator 14 interposed therebetween. It has been turned.

As shown in FIG. 5, the positive electrode body 12 has a sheet-shaped positive electrode current collector 15 and a positive electrode 16 coated on both surfaces of the positive electrode current collector 15.
The positive electrode current collector 15 is formed of a metal foil in a long rectangular shape. As a material for forming the positive electrode current collector 15, for example, aluminum or aluminum alloy can be used. The positive electrode current collector 15 has, for example, a length of 30 to 100 mm, a width of 2 to 10 mm, and a thickness of about 8 to 15 μm. The positive electrode current collector 15 is arranged such that its lateral direction coincides with the axial direction of the winding axis P (see FIG. 3) (hereinafter, simply referred to as “axial direction”).

The positive electrode 16 is formed of a positive electrode active material, a conductive auxiliary agent, and a binder. The positive electrode active material is a composite oxide containing lithium and a transition metal, such as lithium cobalt oxide, lithium titanate, or lithium manganate. The positive electrode 16 is coated on substantially the entire surfaces of both surfaces of the positive electrode current collector 15.

The negative electrode body 13 includes a sheet-shaped negative electrode current collector 18 and a negative electrode 19 coated on both surfaces of the negative electrode current collector 18.
The negative electrode current collector 18 is formed of a metal foil in a long rectangular shape. As a material for forming the negative electrode current collector 18, for example, copper, a copper alloy, nickel, stainless steel, or the like can be used. The length and width of the negative electrode current collector 18 are slightly larger than those of the positive electrode current collector 15 so that the positive electrode body 12 has a smaller area than the negative electrode body 13. The negative electrode current collector 18 is arranged so that its lateral direction coincides with the axial direction.

The negative electrode 19 is formed of a negative electrode active material, a conductive auxiliary agent, and a binder. The negative electrode active material is, for example, silicon oxide, graphite, hard carbon, lithium titanate, LiAl, or the like. The negative electrode 19 is coated on substantially the entire surfaces of both surfaces of the negative electrode current collector 18.

The separator 14 is formed in a long rectangular sheet shape. The separator 14 has a property of allowing lithium ions to pass therethrough, and is formed of, for example, a polyolefin resin porous film, a glass non-woven fabric, a resin non-woven fabric, or the like. The separator 14 has a length that is at least twice the length of the negative electrode current collector 18 and a width that is at least the width of the negative electrode current collector 18. The separator 14 is bent at an intermediate portion in the longitudinal direction and is arranged so as to sandwich the entire positive electrode body 12. At this time, the bent portion of the separator 14 is arranged at a position where it does not interfere with the positive electrode tab 21 described later. Further, the separator 14 is arranged so as to overlap the entire negative electrode body 13 (see FIG. 4 ).

The positive electrode tab 21 is formed integrally with the positive electrode current collector 15. The positive electrode tab 21 extends from one end portion in the axial direction of the edge 15a of the positive electrode current collector 15 in the outermost peripheral portion of the wound positive electrode body 12 in a direction orthogonal to the axial direction. The positive electrode tab 21 has, for example, a length in the extending direction of 2 to 5 mm and a width of about 1 to 5 mm. The positive electrode tab 21 is connected to one current collecting pad 6 of the outer container 2 by ultrasonic welding or the like (see FIG. 2).

The negative electrode tab 22 is formed integrally with the negative electrode current collector 18. The negative electrode tab 22 extends along the direction orthogonal to the axial direction from the other end portion in the axial direction of the edge 18a of the negative electrode current collector 18 in the outermost peripheral portion of the wound negative electrode body 13. .. The negative electrode tab 22 is formed to have the same size as the positive electrode tab 21. As shown in FIG. 4, the negative electrode tab 22 is separated from the positive electrode tab 21 in the axial direction. The negative electrode tab 22 is connected to the other current collecting pad 6 of the outer container 2 by ultrasonic welding or the like (see FIG. 2).

Hereinafter, a method for manufacturing the battery 1 will be described. In addition, please refer to FIG. 1 to FIG. 5 for the reference numerals of the respective components of the battery 1 in the following description.
The method for manufacturing the battery 1 includes a winding step, a tab adjusting step, a tab connecting step, and a sealing step.
First, the winding step is performed. In the winding step, the positive electrode body 12 and the negative electrode body 13 are wound in a state of being laminated via the separator 14 (state shown in FIG. 4). At this time, the positive electrode body 12 and the negative electrode body 13 are arranged so that the end portion of the positive electrode body 12 to which the positive electrode tab 21 is not connected and the end portion of the negative electrode body 13 to which the negative electrode tab 22 is not connected are winding centers. Stack. As a result, the electrode body main body 11 is formed, and the tabs 21 and 22 extend from the electrode body main body 11 to form the electrode body 10.

Next, a tab adjusting step is performed if necessary.
Here, in the winding step described above, when the positive electrode body 12 and the negative electrode body 13 are wound, the relative positions of the edges at the outermost peripheral portions of the positive electrode body 12 and the negative electrode body 13 due to changes in tension during winding and the like. May deviate from the desired relative position in the direction orthogonal to the axial direction. As a result, the positions of the tips of the tabs 21 and 22 are displaced in the direction orthogonal to the axial direction. In this case, the tab adjusting step is performed.
In the tab adjusting step, at least one of the positive electrode tab 21 and the negative electrode tab 22 is cut, and the lengths of the tabs 21 and 22 are adjusted so that the positions of the tip portions of the tabs 21 and 22 are aligned. ..

Next, a tab connecting step is performed. In the tab connecting step, the tabs 21 and 22 are connected to the current collecting pad 6 of the outer container 2 whose inside of the base 3 is opened by ultrasonic welding or the like.

Next, a sealing process is performed. In the sealing step, the electrode body 10 is housed in the outer container 2. More specifically, first, the electrode body 10 in which the tabs 21 and 22 are connected to the collector pad 6 is housed inside the base 3. At this time, a nonaqueous electrolyte such as an electrolytic solution is filled inside the base 3 together with the electrode body 10. Then, the lid 5 is overlapped on the base 3 with the seal ring 4 interposed therebetween, the lid 5 is joined to the seal ring 4 by welding or the like, and the inside of the base 3 is hermetically sealed.
With the above, the manufacture of the battery 1 is completed.

Thus, in the present embodiment, the electrode body 10 includes the positive electrode tab 21 extending from the end edge 15a of the positive electrode current collector 15 in the outermost peripheral portion of the positive electrode body 12 along the direction orthogonal to the axial direction. The negative electrode tab 22 extends along the direction orthogonal to the axial direction from the end edge 18a of the negative electrode current collector 18 at the outermost peripheral portion of the negative electrode body 13.
According to this configuration, the relative position between the edge 15a of the positive electrode current collector 15 at the outermost peripheral portion of the positive electrode body 12 and the edge 18a of the negative electrode current collector 18 at the outermost peripheral portion of the negative electrode body 13 is Even if the tabs 21 and 22 deviate from a desired relative position in the direction orthogonal to the axial direction due to a change in tension during rotation or a tolerance of the electrode length, it is possible to prevent the tabs 21 and 22 from deviating from each other in the axial relative position. As a result, it is possible to prevent the distance between the tabs 21 and 22 from deviating from the design value, so that it is possible to accurately position the tabs 21 and 22 with respect to the pair of current collecting pads 6 of the outer container 2. Therefore, the battery 1 that can be easily manufactured can be provided.

By the way, when the tabs 21 and 22 are connected to the collector pad 6 of the outer container 2, a force is applied to the tabs 21 and 22. Here, in the case of the configuration in which each tab extends from the end face that faces the axial direction of the electrode body as in the prior art, when a force is applied to each tab, the wound positive electrode body and negative electrode body pass through each tab. There is a possibility that the electrode body main body may be collapsed from the wound state by being pulled along the axial direction and pulled out from the end surface of the electrode body.
In the present embodiment, since the tabs 21 and 22 extend along the direction orthogonal to the axial direction, even if a force is applied to the tabs 21 and 22, the positive electrode body 12 and the negative electrode body 13 have the tabs 21 and 22, respectively. It is not pulled through 22 along the axial direction. Therefore, the electrode body 11 can be prevented from collapsing during manufacturing, and the high quality battery 1 can be provided.

Further, since the positive electrode tab 21 is integrally formed with the positive electrode current collector 15 and the negative electrode tab 22 is integrally formed with the negative electrode current collector 18, a tab which is a member different from each current collector 15, 18 is used. There is no need. This can reduce the step of connecting the current collectors 15 and 18 to the tabs 21 and 22. Therefore, the battery 1 that can be easily manufactured can be provided.

Moreover, according to the present embodiment, it is not necessary to use a tab that is a separate member from the current collectors 15 and 18, so that the number of parts can be reduced.
In addition, when using a tab that is a member different from each current collector 15 and 18, a minute projection or the like may be formed at the connection portion between the current collector and the tab due to welding or the like. It is necessary to protect the separator 14 by covering the connecting portion with the tab with an insulating tape. On the other hand, in the present embodiment, since the tabs 21 and 22 are integrally formed with the current collectors 15 and 18, it is not necessary to attach the insulating tape. Therefore, the number of parts can be reduced.
Therefore, the low cost battery 1 can be provided.

Further, since the positive electrode body 12 is formed in a smaller area than the negative electrode body 13, and the separator 14 covers the positive electrode body 12, the contact between the positive electrode body 12 and the negative electrode body 13 is made by the separator 14 having the minimum area. Can be prevented. Therefore, the low cost battery 1 can be provided.

In addition, the method for manufacturing the battery 1 of the present embodiment includes a tab adjusting step of cutting the tip of at least one of the positive electrode tab 21 and the negative electrode tab 22 to adjust the length after the winding step.
According to this method, even when the relative positions of the tabs 21 and 22 in the direction orthogonal to the axial direction deviate from the desired relative positions in the winding step, and the positions of the tip portions of the tabs 21 and 22 become uneven. By adjusting the lengths of the tabs 21 and 22 in the tab adjusting step, the positions of the tip portions of the tabs 21 and 22 can be aligned. This allows the tabs 21 and 22 to be accurately positioned with respect to the pair of current collecting pads 6 of the outer container 2. Therefore, the battery 1 can be easily manufactured.

The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, in the above-described embodiment, as an example of the electrochemical cell, the non-aqueous electrolyte secondary battery has been described as an example, but the present invention is not limited to this case, and the configuration described above for the electric double layer capacitor, the primary battery, or the like is used. Can be applied.

Further, in the above-described embodiment, the tabs 21 and 22 are formed integrally with the current collectors 15 and 18, but the present invention is not limited to this, and the tabs are members separate from the current collectors 15 and 18. It may be. Even with this configuration, the above-described effects can be obtained. That is, each tab can be accurately positioned with respect to the pair of current collecting pads 6 of the outer container 2, a battery that can be easily manufactured can be provided, and collapse of the electrode body main body during manufacturing can be prevented. We can provide quality batteries.

Further, in the above embodiment, the separator 14 is arranged so as to overlap the entire negative electrode body 13, but the present invention is not limited to this, and the separator may cover at least the entire positive electrode body 12. As a result, the area of the separator can be further reduced, and the member cost can be reduced.

In addition, it is possible to appropriately replace the constituent elements in the above-described embodiments with known constituent elements without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1... Battery (electrochemical cell) 2... Exterior container 6... Current collecting pad 10... Electrode body 11... Electrode body 12... Positive electrode body 13... Negative electrode body 14... Separator 15... Positive electrode current collector 15a... Positive electrode current collector Edge 18 of the negative electrode current collector 18a... Edge of the negative electrode current collector 21... Positive electrode tab 22... Negative electrode tab P... Winding shaft

Claims (4)

An outer container having a base formed in a concave shape, and a pair of current collecting pads formed on the inner bottom surface of the base ,
An electrode body housed in the outer container,
The electrode body is
A positive electrode body having a positive electrode current collector, and a negative electrode body having a negative electrode current collector in a state of being laminated via a separator, an electrode body main body wound around a winding axis,
From the edge of the positive electrode current collector in the outermost peripheral portion of the positive electrode body, extending along the direction orthogonal to the axial direction of the winding shaft, a positive electrode tab connected to one of the current collecting pads,
From the edge of the negative electrode current collector in the outermost peripheral portion of the negative electrode body, extending along the direction orthogonal to the axial direction, and a negative electrode tab connected to the other current collecting pad. And an electrochemical cell. The positive electrode tab is integrally formed with the positive electrode current collector,
The negative electrode tab is integrally formed with the negative electrode current collector,
The electrochemical cell according to claim 1, wherein: The positive electrode body is formed in a smaller area than the negative electrode body,
The separator covers the positive electrode body,
The electrochemical cell according to claim 1 or 2, characterized in that. A method for manufacturing an electrochemical cell according to any one of claims 1 to 3, comprising:
A winding step of winding the positive electrode body and the negative electrode body in a laminated state through the separator,
After performing the winding step, a tab adjusting step of cutting at least one tip end portion of the positive electrode tab and the negative electrode tab to adjust the length, and aligning the tip end portions of the positive electrode tab and the negative electrode tab. When,
A method for manufacturing an electrochemical cell, comprising:

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