JP6722545B2 - Insulation member and secondary battery - Google Patents

Description

Embodiments of the present invention relate to an insulating member and a secondary battery.

Lithium-ion secondary batteries have high energy density and are expected as power sources for electric vehicles, hybrid vehicles, electric motorcycles, forklifts, and the like. Further, an assembled battery in which a plurality of batteries are connected has been developed in order to obtain a power source having a larger capacity.

The lithium ion secondary battery includes a metal outer can, a wound electrode group housed in the outer can, leads, and a metal lid attached to an opening of the outer can. The lid is, for example, welded to the opening of the outer can. The wound electrode group has a positive electrode current collector tab at one end in the winding axis direction and a negative electrode current collector tab at the other end. The positive electrode lead is joined to the positive electrode collector tab, and the negative electrode lead is joined to the negative electrode collector tab. The lid is provided with a positive electrode terminal and a negative electrode terminal. These terminals are caulked and fixed to the lid via a gasket, for example, and are insulated from the lid and the outer can. The positive and negative electrode leads joined to the current collecting tab are respectively connected to the positive and negative terminals.

If the current collecting tab contacts the outer can of the battery, the outer can may have a high voltage, especially in the case of an assembled battery. Therefore, in order to insulate the outer can from the current collecting tab, a method of insulating the current collecting tab from the outer can by fitting an insulating member into the wound electrode group and covering the current collecting tab and the lead is adopted. Was there. However, when the insulator is fitted into the wound electrode group, it is difficult to cover all of the plurality of collector tabs made of, for example, aluminum foil with the insulator without leakage. However, there is a problem in that it may come into contact with the outer can without being covered by.

JP, 4-322072, A

Therefore, the problem to be solved by the present invention is to provide an insulating member that reliably insulates the current collecting tab and the outer can.

In order to solve the above problems, the insulating member of the present embodiment, a first surface on which the terminal is arranged, a second surface facing the first surface, further the first surface and the A third surface and a fourth surface arranged between the second surface, a fifth surface facing the third surface, and a sixth surface facing the fourth surface, And an insulating sheet that is housed in the outer can such that the winding axis direction is perpendicular to the third surface and the fifth surface, and except for both ends in the winding axis direction. A member for insulating the wound electrode group from the outer can, which is used in a secondary battery having a wound electrode group covered with a wire, and insulates between the wound electrode group and the first surface. A first insulating member, a second insulating member connected to the first insulating member, and insulating between the wound electrode group and the third surface, and connected to the second insulating member, A third insulating member that insulates between the wound electrode group and a predetermined portion of the fourth surface, and a third insulating member that is continuous with the second insulating member, and is provided with the wound electrode group and the predetermined surface of the sixth surface. A fourth insulating member that insulates between the portion and a fifth insulating member that is continuous with the second insulating member and insulates between the wound electrode group and a predetermined portion of the second surface. , A sixth insulating member connected to the first insulating member and insulating between the wound electrode group and the fifth surface, and connected to the sixth insulating member, and the wound electrode group and the A seventh insulating member for insulating between a predetermined portion of the fourth surface and the sixth insulating member, and insulating between the wound electrode group and a predetermined portion of the sixth surface. to the eighth insulating member, continuous with the sixth insulating member, and a ninth insulating member that insulates between the predetermined portion of the wound and the electrode group said second surface, said predetermined The portion is a portion of the outermost surface of the wound electrode group which is not covered with the insulating sheet .

1 is a perspective view of a secondary battery according to an embodiment. FIG. 3 is an exploded perspective view of the secondary battery according to the embodiment. FIG. 3 is a developed perspective view of an electrode group used in the secondary battery according to the embodiment. FIG. 3 is a schematic diagram of a laminated structure of an electrode group used in the secondary battery according to the embodiment. Sectional drawing which looked at the section along the AA line of FIG. 2 from the arrow direction. FIG. 3 is a perspective view of a wound electrode group and an insulator according to the embodiment. FIG. 3 is an exploded perspective view of the secondary battery according to the embodiment.

Hereinafter, embodiments will be described with reference to the drawings. As an example of the non-aqueous electrolyte secondary battery, a closed type rectangular non-aqueous electrolyte secondary battery 20 is shown in FIGS. 1 and 2. The rectangular nonaqueous electrolyte secondary battery 20 includes an outer can 1, a flat wound electrode group 2, a positive electrode lead 3, a negative electrode lead 4, an insulator 40, a positive electrode terminal 6, and a negative electrode terminal 7.

The outer can 1 includes a first surface 61 on which terminals are arranged and a second surface 62 facing the first surface.
And a third surface 63 and a fourth surface 6 arranged between the first surface and the second surface.
4, a fifth surface 65 facing the third surface, and a sixth surface 66 facing the fourth surface. The outer can 1 is formed of a metal such as aluminum, an aluminum alloy, iron, or stainless. The wound electrode group 2 is inserted from the first surface 61 of the outer can 1 and is housed in the outer can 1 so as to extend in a direction perpendicular to the winding axis.

The wound electrode group 2 has a positive electrode current collecting tab 8a at one end and a negative electrode current collecting tab 9a at the other end.
FIG. 3 shows a developed view of the wound electrode group 2, and FIG. 4 shows a laminated structure of the wound electrode group 2. The positive electrode 8 includes a strip-shaped positive electrode current collector 8c made of, for example, a metal foil, and a positive electrode active material layer 8b formed on one surface or both surfaces thereof. The positive electrode active material layer 8b is formed on the strip-shaped positive electrode current collector 8c such that a region (non-coated portion) of a constant width remains on one end side along the longitudinal direction thereof. This non-coated portion is the positive electrode current collector 8c.
Is an exposed portion, and becomes the positive electrode current collecting tab 8a. Similarly, the negative electrode 9 also includes a strip-shaped negative electrode current collector 9c made of, for example, a metal foil, and a negative electrode active material layer 9b formed on one surface or both surfaces thereof. The negative electrode active material layer 9b is formed on the strip-shaped negative electrode current collector 9c such that a region (non-coated portion) having a constant width remains on the other end side (the side opposite to one end of the positive electrode 8) along the longitudinal direction thereof. .. This non-coated portion is a portion where the negative electrode current collector 9c is exposed and becomes the negative electrode current collector tab 9a.

The positive electrode 8 and the negative electrode 9 are alternately stacked with the strip-shaped separators 10a and 10b. At this time,
The positive electrode current collecting tab 8a is formed on one end side in the winding axis direction, and the negative electrode current collecting tab 9a is formed on the other end side. The separator 10 a stacked under the positive electrode 8 has one end along the longitudinal direction of the positive electrode 8 a.
It is arranged so as to be located inside the end portion on the positive electrode current collector tab side. As a result, the positive electrode current collector tab 8a projects from the positive electrode active material layer 8b, the negative electrode active material layer 9b, and the separator 10a that form the wound electrode group 2. Further, the separator 10a is arranged such that the other end along the longitudinal direction is located outside the other end of the positive electrode 8. The separator 10b sandwiched between the positive electrode 8 and the negative electrode 9 is arranged such that one end along the longitudinal direction thereof is located inside the end of the negative electrode 9 on the negative electrode current collecting tab side. As a result, the negative electrode current collecting tab 9a projects from the positive electrode active material layer 8b, the negative electrode active material layer 9b, and the separator 10b that form the wound electrode group 2. Also, the separator 1
0b is arranged such that the other end along the longitudinal direction thereof is located outside the other end of the negative electrode 9.

The stacked separator 10a, positive electrode 8, separator 10b, and negative electrode 9 are wound, and then
By pressing, the flat wound electrode group 2 is formed.

As shown in FIG. 2, the wound electrode group 2 is wound with an insulating tape 30.
The insulating tape 30 covers an area other than the current collecting tab on the outermost periphery of the wound electrode group 2 to make the area insulative. The number of windings of the insulating tape 30 may be one or more.

In the outer can 1, the first surface 61 on which the terminals are arranged is hermetically fixed to the third surface 63, the fourth surface 64, the fifth surface 65, and the sixth surface 66 by welding, for example. Has been done. The positive electrode terminal 6 and the negative electrode terminal 7 are caulked and fixed to the first surface 61 via insulating gaskets 14 and 15, respectively. The positive electrode terminal 6 and the negative electrode terminal 7 respectively project from the back surface of the first surface 61 toward the inside of the outer can 1. The positive electrode terminal 6 and the negative electrode terminal 7 may be fixed by a hermetic seal using glass in addition to the caulking and fixing with the insulating gaskets 14 and 15 (not shown). Further, the first surface 61 is provided with an inlet 28 for injecting an electrolytic solution and a gas exhaust valve 29 for exhausting gas generated in the secondary battery.

An insulator 40 is provided on the inner side of the outer can 1 with respect to the first surface 61. Insulator 4
Details of 0 will be described later.

The positive electrode lead 3 has a connection plate 3a electrically connected to the positive electrode terminal 6, a through hole 3b opened in the connection plate 3a, and a bifurcated branch from the connection plate 3a. First and second holding strips 3c which are holding portions extending in a direction perpendicular to the
3d and. The connection plate 3a contacts the back surface of the first surface 61 via the insulator 40 at the location of the positive electrode terminal 6, and the positive electrode terminal 6 protruding from the back surface of the first surface 61 caulks and fixes the through hole 3b. ..

The first and second sandwiching strips 3c and 3d of the positive electrode lead 3 sandwich the positive electrode current collector tab 8a from the direction perpendicular to the winding axis, and the first and second sandwiching strips 3c and 3d and the positive electrode current collector tab 3a. 8a
And are joined by welding, for example.

Similarly, the negative electrode lead 4 includes a connection plate 4a, which is a connection portion connected to the negative electrode terminal 7,
A through hole 4b opened in the connection plate 4a, and first and second holding portions which are bifurcated from the connection plate 4a and which extend to the winding electrode group 2 in a direction perpendicular to the winding axis. Holding strips 4c and 4d. The connection plate 4a is in contact with the back surface of the first surface 61 via the insulator 40 at the position of the negative electrode terminal 7 and the through hole 4 is formed in the negative electrode terminal 7 protruding from the back surface.
Clamp and fix b.

The first and second holding strips 4c and 4d of the negative electrode lead 4 sandwich the negative electrode current collecting tab 9a from a direction perpendicular to the winding axis, and the first and second holding strips 4c and 4d and the negative electrode current collecting tab 4a. 9a
And are joined by welding, for example.

The above welding may be performed by a method such as resistance welding or ultrasonic welding.

The positive and negative leads having the above structure can evenly dispose the first and second sandwiching strips with respect to the current collecting tab. In addition, since there are two sandwiching strips (first and second), the collecting distance is shortened. Thereby, the current collection balance can be improved and the current collection efficiency can be improved. Further, in the lead provided with such first and second sandwiching strips, since it is difficult for heat to concentrate at the joint between the current collecting tab and the first and second sandwiching strips and itself, a large current is applied. Even in this case, good electric characteristics can be maintained.

The positive and negative electrode current collecting tabs and the positive and negative electrode leads may be joined together with the current collecting tabs partially fixed by a fixing member as shown in FIG. That is, the positive electrode current collecting tab 8a is fixed by the fixing member 11, and the negative electrode current collecting tab 9a is also fixed by the fixing member 12.

The positive and negative electrode fixing members are symmetrically arranged when fixing the positive and negative electrode current collecting tabs, but have the same shape. Therefore, the fixing member 12 for fixing the negative electrode current collecting tab 9a is taken as an example in FIG.
Will be described in detail. Since the negative electrode current collecting tab 9a is wound, the negative electrode current collecting tab 9a is formed of a hollow elliptical bundle in which a plurality of current collecting tabs are stacked. The fixing member 12 includes U-shaped first and second holding portions 12a and 12b which are respectively fitted and bundled in two locations in the vicinity of the center of the negative electrode current collecting tab 9a, which are opposed to each other in the minor axis direction of the hollow oblong shape. It has a flat connecting portion 12c that connects the first and second holding portions 12a and 2b inside the ellipse formed by the negative electrode current collecting tab 9a. The negative electrode current collecting tab 9a is joined to the first and second holding portions 12a and 12b by, for example, welding.

The first and second holding strips 4c and 4d of the negative electrode lead 4 sandwich the negative electrode current collecting tab 9a to which the fixing member 12 is attached. Thereby, as shown in FIG. 5, the first holding strip 4c
Comes into contact with the outer surface of the first holding portion 12a, and the second holding strip 4d and the second holding portion 12 are brought into contact with each other.
The outer surface of b contacts. At these contact points, the first and second holding strips 4c,
4d and the 1st, 2nd holding parts 12a and 12b are joined by welding, for example.

The above welding may be performed by a method such as resistance welding or ultrasonic welding.

The fixing member 12 is formed of a conductive material such as metal. Therefore, the negative electrode 9 of the wound electrode group 2 is electrically connected to the negative electrode lead 4 through the fixing member 12, and further electrically connected to the negative electrode terminal 7 of the first surface 61 through the negative electrode lead 4.

By using such a fixing member, the thickness of the current collecting tab portion of the wound electrode group 2 can be reduced, and a space for arranging the leads in the outer can can be secured. Since it is not necessary to newly provide a space for leads, the energy density of the battery 20 can be improved.

The fixing member may have a shape having only the independent U-shaped first holding portion and/or the second holding portion and no connecting portion. The first holding portion and the second holding portion may be independently fixed to the negative electrode current collecting tab 9a.

The structure of the fixing member 11 and the fixing form of the positive electrode current collecting tab 8a by the fixing member 11 are the same as those of the fixing member 12 and the negative electrode current collecting tab 9a described above. The fixing member 11 has U-shaped holding portions 11a and 11b and a flat connecting portion 11c.

Subsequently, with respect to the insulator 40 which is the main characteristic part of this embodiment, FIG. 2, FIG. 6 and FIG.
Will be explained.

Note that only the wound electrode group 2 and the insulator 40 are shown in FIG.

As shown in these figures, the insulator 40 is connected to the first insulating member 41 sandwiched between the first surface 61 and the wound electrode group 2, and the first insulating member 41, and Winding electrode group 2 in outer can 1
A second insulating member 42 sandwiched between a first side surface that is perpendicular to the winding axis direction of, and a winding electrode group connected to the second insulating member 42 and in the outer can 1. The second insulating member 43 sandwiched between the second side surface parallel to the winding axis direction of the second winding member 2 and the second insulating member 42, and the winding electrode of the outer can 1. A fourth insulating member 44 sandwiched between a third side surface parallel to the winding axis direction of the group 2 and a second insulating member 42 and a bottom surface of the outer can 1. A fifth insulating member 45 sandwiched between them, and a second side surface that is connected to the first insulating member 41 and that is perpendicular to the winding axis direction of the wound electrode group 2 of the outer can 1. A sixth insulating member 46 sandwiched between the second insulating member 46 and a second side surface which is connected to the sixth insulating member 46 and is parallel to the winding axis direction of the winding electrode group 2 of the outer can 1. The third insulating member 47 sandwiched between the third insulating member 47 and the sixth insulating member 46 and parallel to the winding axis direction of the winding electrode group 2 of the outer can 1. An eighth insulating member 48 sandwiched between the side surface and a side surface, and a ninth insulating member 49 connected to the sixth insulating member 46 and sandwiched between the outer surface and the bottom surface of the outer can.

In the free state before the battery is assembled, the insulator 40 is the first insulating member 41 of the insulator 40.
And the second insulating member 42, the third insulating member 43, the fourth insulating member 44, and the sixth insulating member 4
6, the seventh insulating member 47, the fifth insulating member 45, and the ninth insulating member 49 are substantially coplanar.

The insulator 40 has an insulating property such as polypropylene and is made of a material that does not dissolve in the non-aqueous electrolyte.

Further, for example, a V-shaped groove 50 is provided at the boundary between the insulator 40, the first insulating member 41, and the second insulating member 42. Further, the groove 50 is provided at all boundary parts of the insulator 40, such as a boundary part between the first insulating member 41 and the sixth insulating member 46, a boundary part between the second insulating member 42 and the second side wall insulating part 43, and the like. A groove 50 is provided. The groove 50 has a triangular cross section, for example, and has a structure that can be bent along the groove 50 relatively easily.

According to the above embodiment, the battery can be assembled in the following procedure.

First, as shown in FIG. 2, the wound electrode group 2, the positive electrode lead 3 and the insulator 40 are kept in the free state.
The negative electrode lead 4, the insulator 40, the first surface 61, the positive electrode terminal 6, the negative electrode terminal 7, and the like are assembled.

Next, as shown in FIG. 6, of the insulator 40, a first insulating member 41 and a second insulating member 42.
And the boundary portion between the first insulating member 41 and the sixth insulating member 46 are bent 90 degrees, the second insulating member 42 is brought close to the positive electrode current collecting tab 8a, and the sixth insulating member 46 is removed. Negative electrode current collection tab 9
Approach a.

Then, the boundary between the second insulating member 42 and the third insulating member 43, the boundary between the second insulating member 42 and the fourth insulating member 44, the second insulating member 42 and the fifth insulating member The border with 45,
A boundary portion between the sixth insulating member 46 and the seventh insulating member 47, a boundary portion between the sixth insulating member 46 and the eighth insulating member 48, a sixth insulating member 46 and a ninth insulating member 49, and Boundary parts of each are bent 90 degrees. By doing so, as shown in FIG.
The positive electrode current collecting tab 8a and the negative electrode current collecting tab 9a are covered.

After that, the insulator 40, the wound electrode group 2 and the like are inserted into the outer can 1 in such a state, and finally the first surface 61 and the outer can 1 are airtightly fixed by laser welding or the like.

As described above, the second insulating member 42 of the insulator 40 is brought closer to the positive electrode current collecting tab 8a, and the sixth insulating member 46 is brought closer to the negative electrode current collecting tab 9a, respectively, and then the third insulating member 43, The fourth insulating member 44, the fifth insulating member 45, the seventh insulating member 47, the eighth insulating member 48, and the ninth insulating member 49 are combined into a wound electrode group 2, particularly a wound electrode group 2. Move closer to the power tab. Therefore, it is possible to surely cover all the current collecting tabs with the insulating member.

Further, as described above, the insulator 40 brings the other insulating parts close to the wound electrode group 2 while the second insulating member 42 and the sixth insulating member 46 are brought close to the current collecting tab. Increasing the length of the third insulating member 43, the fourth insulating member 44, the fifth insulating member 45, the seventh insulating member 47, the eighth insulating member 48, and the ninth insulating member 49 in the longitudinal direction. However, the current collecting tab can be reliably covered with the insulating member. Therefore, not only the current collecting tab but also at least a part of the insulating tape 30 covering the wound electrode group 2 can be covered with the insulating member, and the position of the insulator is displaced due to vibration or the like, and the current collecting tab is It is possible to avoid the situation of contact with the outer can.

Further, the insulator 40 does not have a structure in which it is fitted and fixed in the wound electrode group 2 but is insulated by being brought close to the wound electrode group 2, so that the structure of the insulator 40 is not complicated. Molding is also relatively easy.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions can be made without departing from the scope of the invention.
It can be replaced and changed. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and the gist of the invention.

DESCRIPTION OF SYMBOLS 1... Outer can, 2... Winding electrode group, 3... Positive electrode lead, 3a... Connection plate, 3b... Through hole, 3
c...first sandwiching strip, 3d...second sandwiching strip, 4...negative electrode lead, 4a...connection plate, 4b...through hole, 4c...first sandwiching strip, 4d...second sandwiching strip,
6... Positive electrode terminal, 7... Negative electrode terminal, 8a... Positive electrode current collecting tab, 8b... Positive electrode active material layer, 8c... Positive electrode current collector, 9a... Negative electrode current collecting tab, 9b... Negative electrode active material layer, 9c... Negative electrode current collecting Body, 10... Separator, 11, 12... Fixing member, 12a, 12b... 1st, 2nd holding part, 14, 15... Insulation gasket, 20... Battery, 30... Insulation tape, 40... Insulator, 41... One insulating member, 42...
2nd insulating member, 43... 3rd insulating member, 44... 4th insulating member, 45... 5th insulating member, 46... 6th insulating member, 47... 7th insulating member, 48... 8th Insulating member, 49... Ninth insulating member, 61... First surface, 62... Second surface, 63... Third surface, 64... Fourth surface, 65...
Fifth side, 66... Sixth side

Claims (2)

A first surface on which the terminals are arranged, a second surface facing the first surface, and a third surface and a third surface arranged between the first surface and the second surface. An outer can comprising a fourth surface, a fifth surface facing the third surface, and a sixth surface facing the fourth surface, and a winding axis direction of the outer can. Used for a secondary battery having a wound electrode group that is housed so as to be perpendicular to the third surface and the fifth surface and is covered with an insulating sheet except for both ends in the winding axis direction. ,
In a member for insulating the wound electrode group from the outer can,
A first insulating member for insulating between the wound electrode group and the first surface,
A second insulating member connected to the first insulating member and insulating between the wound electrode group and the third surface,
A third insulating member connected to the second insulating member and insulating between the wound electrode group and a predetermined portion of the fourth surface,
A fourth insulating member connected to the second insulating member and insulating between the wound electrode group and a predetermined portion of the sixth surface,
A fifth insulating member that is continuous with the second insulating member and insulates between the wound electrode group and a predetermined portion of the second surface,
A sixth insulating member that is continuous with the first insulating member and insulates between the wound electrode group and the fifth surface,
A seventh insulating member connected to the sixth insulating member and insulating between the wound electrode group and a predetermined portion of the fourth surface,
An eighth insulating member connected to the sixth insulating member and insulating between the wound electrode group and a predetermined portion of the sixth surface,
A ninth insulating member that is continuous with the sixth insulating member and insulates between the wound electrode group and a predetermined portion of the second surface,
Equipped with
The predetermined part is an insulating member which is a part of the outermost surface of the wound electrode group which is not covered with the insulating sheet . A first surface on which the terminals are arranged, a second surface facing the first surface, and a third surface and a third surface arranged between the first surface and the second surface. An outer can comprising a fourth surface, a fifth surface facing the third surface, and a sixth surface facing the fourth surface, and a winding axis direction of the outer can. A secondary battery that is housed so as to be perpendicular to the third surface and the fifth surface, and has a wound electrode group that is covered with an insulating sheet except for both ends in the winding axis direction. ,
A first insulating member for insulating between the wound electrode group and the first surface,
A second insulating member connected to the first insulating member and insulating between the wound electrode group and the third surface,
A third insulating member connected to the second insulating member for insulating between the wound electrode group and a predetermined portion of the fourth surface,
A fourth insulating member connected to the second insulating member for insulating between the wound electrode group and a predetermined portion of the sixth surface,
A fifth insulating member connected to the second insulating member for insulating between the wound electrode group and a predetermined portion of the second surface,
A sixth insulating member connected to the first insulating member for insulating between the wound electrode group and the fifth surface,
A seventh insulating member connected to the sixth insulating member for insulating between the wound electrode group and a predetermined part of the fourth surface,
An eighth insulating member connected to the sixth insulating member for insulating between the wound electrode group and a predetermined portion of the sixth surface,
A ninth insulating member connected to the sixth insulating member for insulating between the wound electrode group and a predetermined portion of the second surface,
Equipped with
The predetermined portion is not covered with the insulating sheet on the outermost surface of the wound electrode group.
The second part is the secondary battery.

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