Pole group connecting structure of laminated lithium battery

Abstract

The utility model discloses a pole group connecting structure of a laminated lithium battery. A positive electrode part and a negative electrode part of the lithium battery are positioned at two ends in the long axis direction of a cell. In the pole group connecting structure, a first pole group and a second pole group have the same polarity, are led out from the same end in the long axis direction of the same battery cell, are spaced in the thickness direction of the battery cell and have overlapped projections; the connecting part is positioned between the two pole groups and is assembled with the two pole groups into an electrically conductive whole; and the flat plate part and the connecting part are assembled into a whole in an electric conduction manner or are integrally arranged with the connecting part. The pole group connecting structure is suitable for large-capacity thick battery cells, is convenient to weld, and can improve the yield of lithium batteries.

Description

Technical Field

[0001] The utility model belongs to the field of lithium ion battery structures, and in particular relates to a pole group connection structure of a large-capacity laminated lithium battery cell. Background Art

[0002] Blade cells, that is, thin-sheet stacked lithium battery cells, facilitate thermal management of lithium batteries.

[0003] The positive and negative pole ears of large-capacity blade batteries are usually located at opposite ends of the long axis. They are stacked with at least 100 layers of pole pieces and ears. They are too thick to be welded, which affects the battery yield and limits the continued improvement of the battery capacity. There is a solution that divides the pole piece and ears at the same end into two groups of equal number to form two pole groups separated in width and with half the thickness. The above pole groups are interconnected with adapters of the same sex, and the adapters are then connected to the poles or cover plates of the battery.

[0004] Patent CN116598723A / 2023 discloses a method for welding the pole ear (i.e., pole group) and the pole column, which uses a vacuum chamber to eliminate the gap between the pole piece and the pole ear, and performs laser welding in the thickness direction of the battery cell. Utility Model Content

[0005] The technical problem to be solved by the utility model is how to improve the pole group connection structure of a laminated lithium battery cell to reduce the cell capacity limitation.

[0006] The utility model discloses a pole group connection structure of a laminated lithium battery.

[0007] The pole group connection structure includes:

[0008] A first pole group and a second pole group have the same polarity, are led out from the same end of the long axis direction of the same battery cell without bending, are spaced from each other in the thickness direction of the battery cell, and their projections overlap each other;

[0009] One or two connecting parts are inserted into the gap between the first pole group and the second pole group, and are assembled with the first pole group and the second pole group to form an electrically conductive whole; and

[0010] A flat plate portion is assembled with the connecting portion through a side surface to be electrically connected as a whole, or is formed integrally with the connecting portion.

[0011] In some embodiments of the present application, it can be selected that there is only one connecting portion, which is projected into a U-shape in the width direction of the battery cell, with the opening facing the battery cell, and the two end faces are respectively connected to the first pole group and the second pole group.

[0012] In some embodiments of the present application, it can be selected that there is only one connecting portion, which is projected as a rectangle in the width direction of the battery cell and respectively connects the first pole group and the second pole group to two opposite end faces.

[0013] In some embodiments of the present application, it can be selected that the connecting parts have two plate-shaped connecting parts, and the outer sides facing away from each other are respectively connected to the first pole group and the second pole group.

[0014] In some embodiments of the present application, the connecting portion may be optionally welded, riveted or bolted to the flat plate portion.

[0015] In some embodiments of the present application, the connecting portion may be welded, riveted or bolted to the first pole group and the second pole group, respectively.

[0016] In some embodiments of the present application, it can be selected that the first electrode group and the second electrode group are configured as the negative electrode of the battery cell.

[0017] Furthermore, the flat plate portion is configured as a negative electrode cover plate of a lithium battery.

[0018] By implementing the technical solution of the utility model, the following beneficial effects can be obtained.

[0019] The utility model discloses a pole group connection structure of a laminated lithium battery. The positive pole part and the negative pole part of the lithium battery are located at the two ends of the long axis direction of the battery cell. In the pole group connection structure, the first pole group and the second pole group: have the same polarity, are led out from the same end of the long axis direction of the same battery cell, are spaced in the thickness direction of the battery cell and their projections overlap; the connection part is located between the two pole groups and is assembled with the two to form an electrically conductive whole; the flat plate part: is assembled with the connection part to form an electrically conductive whole, or is arranged with the connection part. The pole group connection structure is suitable for large-capacity thick batteries, is easy to weld, and can improve the yield rate of lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The following drawings should be used in conjunction with the detailed description.

[0021] The attached drawings are all projections in the width direction of the battery cell.

[0022] Figure 1 is a schematic diagram of the electrode group connection structure in the first embodiment;

[0023] Figure 1a yes Figure 1 A schematic diagram of an assembly of the connecting portion and the flat plate portion shown;

[0024] Figure 2 and Figure 3 They are respectively schematic diagrams of assemblies of the connecting portion and the flat plate portion in other embodiments;

[0025] Figure 4 is a cross-sectional view of a negative electrode cover plate in another embodiment;

[0026] Figure 5 is a schematic diagram of a pole group connection structure in another embodiment;

[0027] Figure 1 and Figure 5 In the figure, the horizontal double arrow line L represents the length direction of the battery cell, and the vertical double arrow line H represents the thickness direction of the battery cell. DETAILED DESCRIPTION

[0028] The embodiments are described below with reference to the accompanying drawings.

[0029] In this specification, unless otherwise specified, one embodiment, some embodiments and other embodiments are used to distinguish different embodiments and do not refer to all embodiments; the accompanying drawings are schematic diagrams, not scale drawings; the directions / positions indicated by top, bottom, center, edge, inside, outside, far, near, vertical, horizontal, up, down, front, back, left, right, etc., based on the observation angle of the accompanying drawings, cannot be understood as the components / devices are located in specific positions and facing specific directions; ordinal words such as first, second, third, etc., do not have a sequential meaning when used to distinguish components / devices with the same function / name.

[0030] Please note that in the following embodiments, "length / width / height" refers to the length / width / thickness dimensions of the battery cell 100, and "pole group" refers to the assembly of the pole ear portions of the positive electrode sheet or negative electrode sheet of a group of stacked units of the same battery cell.

[0031] Embodiment 1

[0032] Disclosed are a pole group connection structure of a laminated lithium battery and a battery cell 100 having the pole group connection structure.

[0033] The laminated lithium battery is an important type of automotive power battery or energy storage battery, which includes multiple battery cells (also known as core packs). The laminated body inside the battery cell is insulated and arranged in an aluminum shell. The laminated unit consists of a positive electrode sheet, a separator and a negative electrode sheet. The ear parts of all positive and negative electrode sheets are insulated and led out of the aluminum shell from the opposite ends of the long axis direction, overlapping each other to form a positive electrode group and a negative electrode group. The electrode group connects the positive electrode column and the negative electrode cover plate exposed on the surface of the lithium battery, or other forms of electrode components.

[0034] The above-mentioned positive electrode group, positive electrode column and / or corresponding cover plate are called the positive electrode part of the lithium battery.

[0035] The negative electrode group, negative electrode column and / or corresponding cover plate are called the negative electrode part of the lithium battery.

[0036] In order to achieve a higher battery charge and discharge rate, when increasing the capacity of a single cell, the safety and reliability of the electrode group connection structure must be ensured.

[0037] Please refer to Figure 1 , the pole group connection structure of Embodiment 1 includes a first pole group 111, a second pole group 112, a connection part 211, and a flat part 220.

[0038] Please note that the following plate-shaped or block-shaped connection part 211 may habitually continue to be called a "connection tab" in the lithium battery industry.

[0039] Figure 1 It schematically shows one end in the long axis direction of the battery cell 100. The stacked body inside the battery cell 100 includes at least 100 stacked units. Each stacked unit is composed of a positive electrode sheet, a separator, and a negative electrode sheet. The stacked units are divided into the following two groups: the first group of stacked units 101 and the second group of stacked units 102.

[0040] The pole ear part of the negative electrode sheet of the first group of stacked units 101 is led out of the aluminum shell at the Figure 1 shown end to form the first pole group 111. The pole ear part of the negative electrode sheet of the second group of stacked units 101 is led out of the aluminum shell at the Figure 1 shown end to form the second pole group 112. The first pole group 111 and the second pole group 112 are spaced apart from each other. After assembly, they have no bending and their projections coincide in the thickness direction of the battery cell.

[0041] That is, the first pole group 111 and the second pole group 112: they have the same polarity (collectively serving as the negative electrode of the battery cell 100), they are led out without bending from the same end in the long axis direction of the same battery cell 100, and they are spaced apart from each other and their projections coincide with each other in the thickness direction of the battery cell 100.

[0042] The connection part 211 projects as a C-shaped (or U-shaped) in the width direction of the battery cell 100, with its opening facing the battery cell 100. It is inserted into the gap between the first pole group 111 and the second pole group 112 and welded to the first pole group 111 and the second pole group 112 to form an electrically conductive whole.

[0043] Please refer to Figure 1 and Figure 1a , one arm 2111 of the connection part 211 is welded to the inside of the first pole group 111. The other arm 2112 of the connection part 211 is welded to the inside of the second pole group 112. The bottom 2113 of the connection part 211 is welded to the side of the flat part 220 facing the battery cell 100.

[0044] The connecting portion 211 is welded to the flat plate portion 220 in advance, and then welded to the two pole groups 211 and 212 by the method disclosed in paragraphs 54 to 73 of the patent CN116598723A / 2023 specification. Specifically, the connecting portion 211 is inserted to space the two pole groups 111 and 112 from each other, and then the gap between the pole piece and the pole ear is eliminated in the vacuum chamber, thereby compressing the thickness of the two pole groups 111 and 112, and the laser penetrates the two pole groups 111 and 112 in the normal direction of the negative pole piece and the pole ear.

[0045] The two electrode groups 111 and 112 must be neatly shaped. The two electrode groups 111 and 112 can be trimmed before welding to make the width equal to the width of the connecting portion 211, but longer; the ear portion of each negative electrode sheet can also be separately configured in advance to make the overall shape of the electrode groups consistent after welding.

[0046] The flat plate portion 220 is configured as a negative electrode cover of the lithium battery. One side surface of the flat plate portion 220 is perpendicular to the length direction of all the cells 100 of the lithium battery and is welded with the plurality of connecting portions 211 to form an electrically conductive whole.

[0047] The structure of the positive electrode of the lithium battery is similar to the structure of the negative electrode described above, and will not be described in detail.

[0048] The technical advantages of the above-mentioned electrode group connection structure are: 1) the capacity of the battery cell 100 is not limited, the width of the two electrode groups 111 and 112 is not limited, the connecting part 211 can be a block, and the flat plate part 220 can be a thick plate, which is suitable for large-capacity battery cells; 2) it is conducive to improving the yield rate, the two electrode groups 111 and 112 are not bent, the thickness is controllable, and the width can be close to the width of the battery cell 100. Regardless of welding, riveting or bolt assembly, the structural stability and reliable conductivity can be guaranteed.

[0049] See also Figure 2 In other embodiments, a connecting portion 213 is used to replace the connecting portion 211. The connecting portion 213 is projected into a rectangular shape in the width direction of the battery cell 100, and the first electrode group 211 and the second electrode group 212 are welded to two opposite end surfaces.

[0050] See also Figure 3 In other embodiments, two connecting parts 215 are used to replace the connecting part 211. The two connecting parts 215 are in the form of thick plates parallel to each other, and the first pole group 211 and the second pole group 212 are welded to the opposite outer sides thereof.

[0051] See also Figure 4In another embodiment, two connecting parts 215' are used to replace the connecting part 211. The two connecting parts 215' and the flat part 220' are integrally formed into the negative electrode cover 200. The two connecting parts 215' of the negative electrode cover 200 are parallel to each other, and the outer sides of the two opposite sides are respectively welded with the first electrode group 211 and the second electrode group 212.

[0052] See also Figure 5 In another embodiment, the battery cell 100' is thicker and its stacking units are divided into 4 groups. Figure 5 A connection portion 211 is welded between the pole ear portions of the two upper stacked units to form the upper two pole groups 121, and then Figure 5 Another connecting portion 211 is welded between the pole lugs of the two stacked units in the middle and lower parts to form the two lower pole groups 121, and finally the flat plate portion 220 is assembled. Please note that the opening of the connecting portion 211 faces away from the battery cell 100' to facilitate the welding operation.

[0053] In other embodiments, the connecting portion 220 and the flat plate portion 211 may be assembled by riveting or bolting, and the connecting portion 220 and the first electrode group 111 and the second electrode group 112 may be assembled by riveting or bolting.

[0054] In other embodiments, the positive electrode portion of the lithium battery has the following differences compared to the negative electrode portion of the first embodiment: its flat plate portion 220 is used to weld the positive electrode column, and the positive electrode column passes through and / or is welded to the positive electrode cover plate.

[0055] The above embodiments, application examples and technical analysis are intended to introduce the technical concept and features of the utility model so that those skilled in the art can implement the technical solution of the utility model, and do not constitute any limitation on the protection scope of the utility model. Simple changes and equivalent transformations to the above embodiments are within the protection scope of the utility model.

Claims

1. A pole group connection structure of a laminated lithium battery, characterized in that include: A first pole group and a second pole group have the same polarity, are led out from the same end of the long axis direction of the same battery cell without bending, are spaced from each other in the thickness direction of the battery cell, and their projections overlap each other; One or two connecting parts are inserted into the gap between the first pole group and the second pole group, and are assembled with the first pole group and the second pole group to form an electrically conductive whole; and A flat plate portion is assembled with the connecting portion through a side surface to be electrically connected as a whole, or is formed integrally with the connecting portion.

2. The pole group connection structure according to claim 1, characterized in that: There is only one connecting portion, which is projected into a U-shape in the width direction of the battery cell, with the opening facing the battery cell, and the two end faces are respectively connected to the first pole group and the second pole group.

3. The pole group connection structure according to claim 1, characterized in that: There is only one connecting portion, which is projected into a rectangle in the width direction of the battery cell, and is respectively connected to the first pole group and the second pole group on two opposite end faces.

4. The pole group connection structure according to claim 1, characterized in that: There are two connecting parts in the form of plates parallel to each other, and the outer sides facing away from each other are respectively connected to the first pole group and the second pole group.

5. The pole group connection structure according to claim 1, characterized in that: The connecting portion is welded, riveted or bolted to the flat plate portion.

6. The pole group connection structure according to claim 1, characterized in that: The connecting portion is respectively welded, riveted or bolted to the first pole group and the second pole group.

7. The pole group connection structure according to claim 1, characterized in that: The first electrode group and the second electrode group are configured as negative electrodes of the battery cell.

8. The pole group connection structure according to claim 7, characterized in that: The flat plate portion is configured as a negative electrode cover plate of a lithium battery.

9. The electrode group connection structure according to claim 1, characterized in that: The first electrode group and the second electrode group are configured as the positive electrode of the battery cell.

10. The pole group connection structure according to claim 9, characterized in that: The flat plate portion is used for welding the positive electrode column of the lithium battery, or is configured as a positive electrode cover plate of the lithium battery.

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