Laminated cell structure

Abstract

The utility model discloses a kind of laminated cell structures, including shell and bare cell, the shell inside is provided with gas storage area and packaging area, the bare cell is packaged in the packaging area;The bare cell includes diaphragm, multiple positive pole piece and multiple negative pole piece, the bare cell has thickness direction, multiple the positive pole piece and multiple the negative pole piece are alternately stacked along the thickness direction;The diaphragm is continuous folding structure, including multiple main body portion and multiple turnover portion which are alternately arranged, adjacent the positive pole piece and the negative pole piece are separated by the main body portion, one end of adjacent the main body portion is connected by the turnover portion, the gas storage area is located one side of the packaging area.The utility model is helpful to bare cell internal gas discharge, improve battery cycle life and safety.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a stacked cell structure. Background Technology

[0002] With the development of new energy technologies, lithium-ion batteries have been widely used in power, energy storage, and digital fields. There are two main processing methods for bare lithium-ion battery cells: winding and stacking. Among these, Z-type stacking technology is more widely used. It improves the energy density and structural stability of the battery through a unique stacking method, ensuring long cycle life and high reliability.

[0003] In a bare cell fabricated using Z-shaped laminations, the separator rotates on both sides of the bare cell, and each rotation causes the separator to wrap around the electrode. Utility Model Content

[0004] In Z-shaped stacked bare cells, the separator rotates on both sides of the bare cell. When this technology is used in pouch cells, one side of the bare cell corresponds to the gas pocket of the pouch battery. During final sealing and evacuation, the gas between the electrodes and the separator is blocked by the separator at the rotation point, making evacuation difficult and preventing the gas between the electrodes and the separator from being completely discharged. This leads to lithium plating during subsequent charge and discharge processes, affecting the battery's cycle life and posing a risk of thermal runaway. To overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a stacked cell structure that facilitates the discharge of gas inside the bare cell, improving the battery's cycle life and safety.

[0005] The objective of this utility model is achieved through the following technical solution:

[0006] A stacked battery cell structure includes a casing and a bare battery cell. The casing contains a gas storage area and a packaging area, and the bare battery cell is packaged within the packaging area. The bare battery cell includes a separator, multiple positive electrode plates, and multiple negative electrode plates. The bare battery cell has a thickness direction, and the multiple positive electrode plates and multiple negative electrode plates are stacked alternately along the thickness direction. The separator is a continuously folded structure, including multiple alternating main body portions and multiple folded portions. Adjacent positive electrode plates and negative electrode plates are separated by the main body portions, and one end of adjacent main body portions is connected by the folded portions. The gas storage area is located on one side of the packaging area, and an exhaust structure is provided on the folded portion near the gas storage area. When the battery cell structure is subjected to final sealing and gas extraction, the exhaust structure is used to discharge the gas inside the bare battery cell into the gas storage area.

[0007] In one embodiment, the bare cell has a width direction, and the venting structure is a plurality of vent holes arranged in a single row along the width direction, the vent holes penetrating the diaphragm located in the folded portion.

[0008] In one embodiment, the folding portion includes an axis of symmetry, and the center point of each of the exhaust holes is located on the axis of symmetry.

[0009] In one embodiment, the bare cell has a width direction, and the venting structure consists of multiple rows of vent holes arranged along the width direction, the vent holes penetrating the diaphragm located in the folded portion.

[0010] In one embodiment, the exhaust holes of the exhaust structure are in an even-numbered row, and the folded portion includes an axis of symmetry, with the even-numbered rows of exhaust holes symmetrically distributed about the axis of symmetry.

[0011] In one embodiment, the exhaust holes of the exhaust structure are in an odd number of columns, the folded portion includes an axis of symmetry, the center point of the exhaust holes in the central column is located on the axis of symmetry, and the exhaust holes in the remaining columns are symmetrically distributed with respect to the axis of symmetry.

[0012] In one embodiment, the distance between two adjacent exhaust holes along the width direction is L1, where 1mm ≤ L1 ≤ 20mm.

[0013] In one embodiment, the vent hole includes a circular hole, an elliptical hole, or a polygonal hole; when the vent hole is a circular hole, its diameter is D, 0.5mm≤D≤5mm.

[0014] In one embodiment, the diaphragm has a continuous Z-shaped fold structure.

[0015] In one embodiment, the outer casing is an aluminum-plastic film.

[0016] The beneficial effects of this utility model are as follows: by setting an exhaust structure at the folded part of the separator, the gas between the electrode and the separator is no longer blocked by the separator during the final sealing and gas extraction of the battery cell. It can be discharged to the outside of the bare battery cell through the exhaust structure, which has a good degassing effect, avoids gas remaining in the battery cell, and improves the battery cycle life and safety. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the stacked battery cell structure according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of bare battery cell stacking;

[0020] Figure 3 This is a schematic diagram of the structure of a bare battery cell before the separator is folded, according to one embodiment.

[0021] Figure 4 yes Figure 3 A schematic diagram of the folded diaphragm structure;

[0022] Figure 5 This is a schematic diagram of the structure of a bare battery cell before the separator is folded, according to another embodiment.

[0023] Figure 6 yes Figure 5 A schematic diagram of the folded diaphragm structure;

[0024] Figure 7 This is a schematic diagram of the structure of a bare battery cell before the separator is folded, according to another embodiment.

[0025] Figure 8 yes Figure 7 A schematic diagram of the folded diaphragm structure;

[0026] In the diagram: 1. Outer casing; 11. Gas storage area; 12. Encapsulation area; 2. Bare cell; 21. Separator; 211. Main body; 212. Folding part; 213. Vent hole; 22. Positive electrode plate; 23. Negative electrode plate; 24. Positive electrode tab; 25. Negative electrode tab. Detailed Implementation

[0027] The specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of this utility model. Based on the description of this utility model, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this utility model.

[0028] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0029] The terms “upper,” “lower,” “left,” “right,” “front,” “back,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of description and simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0030] The terms “first,” “second,” “third,” etc., are used merely to distinguish elements with similar properties, not to indicate or imply relative importance or a specific order.

[0031] The terms “include,” “comprising,” or any other variation thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0032] This utility model provides a stacked cell structure, such as Figure 1 and Figure 2 As shown, the device includes a housing 1 and a bare cell 2. The housing 1 has a gas storage area 11 and a packaging area 12 inside, and the bare cell 2 is packaged in the packaging area 12. The bare cell 2 includes a separator 21, multiple positive electrode plates 22 and multiple negative electrode plates 23. The bare cell 2 has a thickness direction T, and the multiple positive electrode plates 22 and multiple negative electrode plates 23 are stacked alternately along the thickness direction T. The separator 21 has a continuous folded structure, including multiple alternating main body parts 211 and multiple folded parts 212. Adjacent positive electrode plates 22 and negative electrode plates 23 are separated by the main body parts 211. One end of adjacent main body parts 211 is connected by the folded parts 212, and the other end is an open structure. The folded parts 212 and the open structure are alternately arranged along the thickness direction T. The gas storage area 11 is located on one side of the packaging area 12. An exhaust structure is provided on the folded parts 212 near the gas storage area 11. When the cell structure is sealed and evacuated, the exhaust structure is used to discharge the gas in the bare cell 2 into the gas storage area 11.

[0033] In this embodiment, the continuous folding structure design of the diaphragm 21 isolates the positive and negative electrode plates to prevent short circuits. The folded part 212 integrates an exhaust structure, which facilitates the discharge of gas inside the bare cell 2 into the gas storage area 11 (gas bag) when the cell structure is finally sealed and evacuated, thus avoiding gas residue inside the cell and improving battery cycle life and safety.

[0034] Specifically, during the final sealing and evacuation process (e.g., piercing the gas storage area 11 with a dagger), the gas between the electrode and the separator is discharged to the gas storage area 11 through the venting structure on the folded part 212, reducing the evacuation resistance and allowing the gas between the electrode and the separator to be completely discharged. After evacuation, heat sealing is performed at the connection between the encapsulation area 12 and the gas storage area 11, and then the gas storage area 11 is removed, leaving the encapsulation area 12 intact. The bare cell 2 also includes a positive electrode tab 24 connected to the positive electrode 22 and a negative electrode tab 25 connected to the negative electrode 23. Both the positive electrode tab 24 and the negative electrode tab 25 are exposed outside the outer casing 1 to lead the current to the outside, realizing the charging and discharging function of the battery.

[0035] As one implementation method, such as Figure 3 and Figure 4 As shown, the bare cell 2 has a width direction W, and the venting structure consists of multiple vent holes 213 arranged in a single row along the width direction W. The vent holes 213 penetrate the diaphragm 21 located in the folded portion 212. In this embodiment, the single row of vent holes 213 is evenly distributed along the width direction W, which can evenly discharge gas within the width range of the bare cell 2, avoiding local gas accumulation. At the same time, the single row layout simplifies the processing difficulty of the venting structure and reduces manufacturing costs.

[0036] As one implementation method, such as Figure 3 and Figure 4 As shown, the folding portion 212 includes a symmetry axis A, and the center point of each vent 213 is located on the symmetry axis A. In this embodiment, the vent 213 are aligned along the center of the symmetry axis A of the folding portion 212. When the diaphragm 21 is folded along the symmetry axis A, the single row of vent 213 folds in half and corresponds to each other, ensuring that the single row of vent 213 is always unobstructed, improving venting efficiency while reducing stress concentration inside the cell and enhancing structural stability.

[0037] As one implementation method, such as Figures 5 to 8 As shown, the bare cell 2 has a width direction W, and the venting structure consists of multiple rows of vent holes 213 arranged along the width direction W. The vent holes 213 penetrate the diaphragm 21 located in the folded portion 212. In this embodiment, the arrangement of multiple rows of vent holes 213 expands the coverage of the gas emission path, which can meet the large gas production requirements of high-energy-density cells. The parallel venting of multiple rows improves the overall venting efficiency, avoids venting failure caused by blockage of a single path, and enhances the reliability of the cell during cyclic charging and discharging.

[0038] As one implementation method, such as Figure 5 and Figure 6As shown, the exhaust holes 213 of the exhaust structure are arranged in an even-numbered row. The folded portion 212 includes a symmetry axis A. The even-numbered rows of exhaust holes 213 are symmetrically distributed with respect to the symmetry axis A, and the positions of the mutually symmetrical exhaust holes 213 are mirror images of each other. In this embodiment, the number of rows of exhaust holes 213 on both sides of the symmetry axis A is equal, and the hole spacing of the corresponding rows is the same. When the diaphragm 21 is folded along the symmetry axis A, the symmetrical layout of the even-numbered rows makes the exhaust holes 213 form mirror paths on both sides of the folded portion 212. That is, the exhaust holes 213 on one side of the symmetry axis A correspond to the exhaust holes 213 on the other side of the folded diaphragm 21, ensuring that the exhaust holes 213 are always unobstructed after folding. At the same time, gas is discharged from both sides of the bare cell 2, balancing the gas pressure on both sides of the cell, reducing cell deformation or local bulging of the outer casing 1 caused by uneven exhaust, and improving the uniformity of the cell appearance and safety. The device can be configured with two rows of exhaust holes 213, one row on each side of the axis of symmetry A. The two rows of exhaust holes 213 are symmetrically distributed with the axis of symmetry A as the reference, and the positions of the two rows of exhaust holes 213 are mirror images of each other.

[0039] As one implementation method, such as Figure 7 and Figure 8 As shown, the exhaust holes 213 of the exhaust structure are arranged in an odd number of rows. The folded portion 212 includes a symmetry axis A. The center points of the exhaust holes 213 in the central row are all located on the symmetry axis A, meaning that the center line of the exhaust holes 213 in the central row coincides with the symmetry axis A. The exhaust holes 213 in the remaining rows are symmetrically distributed with respect to the symmetry axis A, and the positions of the two symmetrical rows of exhaust holes 213 correspond to each other. In this embodiment, except for the central row, the number of rows of exhaust holes 213 is even. They extend to both sides with the central row as the reference, ensuring efficient exhaust in the central area and achieving uniform gas diffusion through the symmetrical positions on both sides. This is suitable for scenarios with a large cell width, and can take into account the exhaust needs of the central and edge areas, avoiding the risk of local overheating caused by gas stagnation at the edges. Specifically, three rows of exhaust holes 213 can be provided. The center points of the exhaust holes 213 in the central row are all located on the symmetry axis A. One row is provided on each side of the symmetry axis A, and the two rows of exhaust holes 213 are symmetrically distributed with respect to the symmetry axis A, and the positions of the two symmetrical rows of exhaust holes 213 correspond to each other.

[0040] As one implementation method, such as Figure 3 As shown, along the width direction W, the distance between two adjacent vent holes 213 is L1, where 1mm ≤ L1 ≤ 20mm, preferably 5mm ≤ L1 ≤ 10mm. In this embodiment, the spacing between the vent holes 213 is limited to a reasonable range, which avoids both a decrease in the strength of the diaphragm 21 or interference at the hole positions due to excessively small spacing, and a blind zone for venting due to excessively large spacing. By optimizing the hole spacing, the number of vent holes 213 can be maximized while ensuring the structural strength of the diaphragm 21, thus achieving a balance between venting efficiency and mechanical performance.

[0041] In one embodiment, the vent 213 includes a circular hole (such as...). Figure 3 The vent hole 213 can be circular (as shown), with an elliptical or polygonal shape. When the vent hole 213 is circular, its diameter is D, where 0.5mm ≤ D ≤ 5mm, preferably 1mm ≤ D ≤ 2mm. Circular holes have a mature manufacturing process, low edge stress concentration, and are less likely to cause tearing of the diaphragm 21. Elliptical holes can optimize the venting path along the gas flow direction. Polygonal holes (such as square holes) are easy to arrange in an array to increase venting density. Limiting the diameter range of circular holes prevents both excessively small venting holes that could hinder venting and excessively large venting holes that could weaken the diaphragm 21's isolation effect on the positive and negative electrodes, ensuring compatibility between safety and functionality.

[0042] In one implementation, the diaphragm 21 has a continuous Z-shaped folded structure, which forms a stable zigzag support between the positive and negative electrodes.

[0043] In one implementation, the outer casing 1 is an aluminum-plastic film; the aluminum-plastic film combines the barrier properties of the aluminum layer to prevent moisture intrusion and gas leakage with the flexibility of the plastic layer, which can adapt to the expansion and contraction during the charging and discharging process of the battery cell, avoiding the rigid compression of the metal outer casing 1 that could damage the internal structure of the battery cell; at the same time, the aluminum-plastic film is lightweight, which helps to reduce the overall weight of the battery cell and increase the energy density.

[0044] As one implementation method, such as Figure 5 As shown, before the diaphragm 21 is folded, the distance from the vent hole 213 to the negative electrode 23 on the side closest to the encapsulation area 12 is L2, and the distance from the vent hole 213 to the negative electrode 23 on the side farthest from the encapsulation area 12 is L3; L2 ranges from 0.3mm to 3mm, preferably from 0.5mm to 1mm; L3 ranges from 0.8mm to 8mm, preferably from 1.5mm to 4mm.

[0045] This invention arranges vent holes 213 on the folded portion 212 of the separator 21 of the bare cell 2 adjacent to the gas storage area 11 (gas bag), so that when the stacked cell structure is sealed and evacuated, the gas between the electrode and the separator 21 is no longer blocked by the separator 21, and is discharged to the outside of the bare cell 2 through the vent holes 213; the degassing effect is good, avoiding gas residue in the bare cell 2, and improving the cycle life and safety of the battery.

[0046] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content without departing from the scope of the technical solution of the present utility model. These are equivalent embodiments with equivalent changes. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the technical solution of the present utility model shall still fall within the protection scope of the technical solution of the present utility model.

Claims

1. A stacked battery cell structure, characterized in that, The device includes a housing (1) and a bare cell (2). The housing (1) has an internal gas storage area (11) and an encapsulation area (12). The bare cell (2) is encapsulated in the encapsulation area (12). The bare cell (2) includes a separator (21), multiple positive electrode plates (22), and multiple negative electrode plates (23). The bare cell (2) has a thickness direction (T). The multiple positive electrode plates (22) and the multiple negative electrode plates (23) are stacked alternately along the thickness direction (T). The separator (21) has a continuously folded structure and includes multiple alternating main body portions (21). 1) and multiple folding portions (212), adjacent positive electrode plates (22) and negative electrode plates (23) are separated by the main body portion (211), one end of adjacent main body portions (211) is connected by the folding portion (212), the gas storage area (11) is located on one side of the encapsulation area (12), and an exhaust structure is provided on the folding portion (212) near the gas storage area (11). When the cell structure is sealed and evacuated, the exhaust structure is used to discharge the gas in the bare cell (2) into the gas storage area (11).

2. The stacked cell structure as described in claim 1, characterized in that, The bare cell (2) has a width direction (W), and the exhaust structure is a plurality of exhaust holes (213) arranged in a single row along the width direction (W), and the exhaust holes (213) penetrate the diaphragm (21) located in the folded portion (212).

3. The stacked cell structure as described in claim 2, characterized in that, The folding section (212) includes an axis of symmetry (A), and the center point of each of the exhaust holes (213) is located on the axis of symmetry (A).

4. The stacked cell structure as described in claim 1, characterized in that, The bare cell (2) has a width direction (W), and the exhaust structure consists of multiple rows of exhaust holes (213) arranged along the width direction (W), with the exhaust holes (213) penetrating the diaphragm (21) located in the folded portion (212).

5. The stacked cell structure as described in claim 4, characterized in that, The exhaust holes (213) of the exhaust structure are in an even number of rows, and the folded part (212) includes an axis of symmetry (A). The exhaust holes (213) in the even number of rows are symmetrically distributed with respect to the axis of symmetry (A).

6. The stacked cell structure as described in claim 4, characterized in that, The exhaust holes (213) of the exhaust structure are in an odd number of rows. The folded part (212) includes an axis of symmetry (A). The center point of the exhaust holes (213) in the central row is located on the axis of symmetry (A). The exhaust holes (213) in the remaining rows are symmetrically distributed with respect to the axis of symmetry (A).

7. The stacked cell structure as described in claim 2 or 4, characterized in that, Along the width direction (W), the distance between two adjacent exhaust holes (213) is L1, where 1mm≤L1≤20mm.

8. The stacked cell structure as described in claim 2 or 4, characterized in that, The exhaust hole (213) includes a circular hole, an elliptical hole, or a polygonal hole; when the exhaust hole (213) is a circular hole, its diameter is D, 0.5mm≤D≤5mm.

9. The stacked cell structure as described in claim 1, characterized in that, The diaphragm (21) has a continuous Z-shaped fold structure.

10. The stacked cell structure as described in claim 1, characterized in that, The outer shell (1) is an aluminum-plastic film.

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