CN220856746U - Battery module structure and battery pack - Google Patents

Abstract

The utility model discloses a battery module structure and a battery pack, comprising: the battery cells are sequentially arranged along the thickness direction of the battery cells, each battery cell comprises a first expansion surface and a second expansion surface opposite to the first expansion surface in the arrangement direction of the battery cells, and at least one of the first expansion surface and/or the second expansion surface comprises a flat part and a non-flat part; and the buffer material is arranged between every two adjacent cells along the arrangement direction of the cells, and is positioned at the position where the thickness of the flat part is different from that of the non-flat part, or the density of the buffer material is different from that of the flat part. According to the utility model, the buffer material matched with the surface of the battery cell is adopted, so that the degree of adaptation with the battery cell is improved, the problem of uneven stress among different parts of the battery cell is reduced, and finally, the stress of all points of the battery cell is nearly consistent, thereby improving the safety of the battery cell.

Description

Battery module structure and battery pack

Technical Field

The utility model relates to the technical field of batteries, in particular to a battery module structure and a battery pack.

Background

Lithium ion batteries expand during cycling, and buffer materials are typically used to absorb expansion of the cells during design and manufacture of battery packs and modules. For example, the patent CN209804747U and CN209104207U use buffer materials such as foam to absorb cell expansion. In the practical application process, in order to facilitate production and control, the buffer materials between the battery cells are uniform in thickness and uniform in density.

However, the electrode sheet is thinned because the active material is peeled off when the electrode sheet is coated to prevent concentration of edge stress. Therefore, the thicknesses of different areas of the electrode plate of the battery cell are different, and the surface of the battery cell is uneven. After the buffer material with uniform thickness is stuck on the surface of the battery core, uneven stress at local positions can be necessarily caused. In particular, when there are a large number of stacked cells, the entire module or battery pack may be tapered. When the local stress of the battery cell is uneven, lithium is preferentially separated from the part with too small stress or too large stress, so that the whole cycle of the battery pack is deteriorated.

Disclosure of utility model

In order to overcome at least one of the above-mentioned drawbacks of the prior art, the present utility model provides a battery module structure and a battery pack. The problem of uneven stress of the battery cell when the surface of the battery cell is uneven can be solved, the phenomenon of lithium precipitation is reduced, and the service life and the safety performance of the battery cell are improved.

The utility model adopts the technical proposal for solving the problems that:

A battery module structure, comprising: the battery cells are sequentially arranged along the thickness direction of the battery cells, each battery cell comprises a first expansion surface and a second expansion surface opposite to the first expansion surface in the arrangement direction of the battery cells, and at least one of the first expansion surface and/or the second expansion surface comprises a flat part and a non-flat part; and the buffer material is arranged between every two adjacent cells along the arrangement direction of the cells, and is positioned at the position where the thickness of the flat part is different from that of the non-flat part, or the density of the buffer material is different from that of the flat part.

Through adopting above-mentioned scheme, through adopting the buffer material with electric core surface adaptation, improve the adaptation degree with electric core, reduce the inhomogeneous problem of atress between the different positions of electric core, the atress that makes all points of electric core finally is close unanimously to improve the security of electric core.

Further, in the arrangement direction of the electric cells, end buffer materials are arranged on the outer sides of the two electric cells positioned at the edge, and the surface of one side of the end buffer materials, far away from the electric cells, is a flat plane.

Through adopting above-mentioned scheme, make the whole rectangular structure that is after the electric core is arranged, the phenomenon of slope, protrusion or recess can not appear.

Further, the non-planar portion includes a cell recess and/or a cell protrusion.

Further, the surface of the buffer material, which is contacted with the non-flat part of the battery cell, comprises a first material part correspondingly attached to the concave part of the battery cell and/or a second material part correspondingly attached to the convex part of the battery cell, wherein the thickness of the first material part is greater than the thickness of the flat part of the buffer material and greater than the thickness of the second material part.

By adopting the scheme, the inconsistent stress of the surface of the battery cell is compensated by designing the buffer material with nonuniform thickness, and the buffer material at the position is thinned at the thicker part of the surface of the battery cell; the buffer material at the position is thicker at the thinner position of the surface of the battery cell; and ensuring that all points of the battery cell are stressed nearly uniformly.

The surface of the buffer material, which is contacted with the non-flat part of the battery cell, comprises a first material part correspondingly attached to the concave part of the battery cell and/or a second material part correspondingly attached to the convex part of the battery cell, wherein the density of the first material part is greater than that of the flat part of the buffer material and is greater than that of the second material part.

By adopting the scheme, the non-uniformity of the stress on the surface of the battery cell is improved by designing the buffer material with non-uniform density. The density of the buffer material at the position is reduced at the position where the surface of the battery cell is thicker, and the density of the buffer material is increased at the position where the surface of the battery cell is thinner. And finally, the stress of all points of the battery cell is nearly consistent.

Further, a plurality of spacing units are arranged in the buffer material at intervals, and each spacing unit comprises: the rigid unit is positioned in the center of the buffer material and comprises two opposite supporting surfaces along the arrangement direction of the battery cells; and the elastic unit is connected to the supporting surface of the rigid unit.

By adopting the scheme, the limiting unit can further prevent the non-uniformity of the expansion of the battery cell. When the battery cell circulates, the expansion of the local position is larger, the battery cell shell compresses the buffer material and contacts the limiting unit, the extrusion force of the limiting unit to the battery cell is larger than that of the buffer material, so that the local position of the battery cell cannot be displaced, and the stress is relatively reduced. The rigidity and the extrusion resistance of the elastic unit are superior to those of the buffer material, the elastic unit has a compression resistance effect, and the rigid unit can prevent the local position of the battery cell from being stressed excessively and perform rigid buffer.

Further, the elastic unit comprises a connecting surface abutted with the supporting surface of the rigid unit and a bearing surface opposite to the connecting surface.

Further, the bearing surface area is larger than the connecting surface area.

Further, the width of the elastic unit gradually increases in the direction from the connection surface to the support surface.

Further, in the width direction of the elastic unit, the middle part of the bearing surface of the elastic unit protrudes to the side far away from the connecting surface to form an arc surface.

Through adopting above-mentioned scheme, the elastic element is located the rigid unit both sides, and the bearing of contact with the electric core personally submits certain range, is favorable to carrying out the point contact with the electric core, and the elastic element middle part is the arc, can increase the contact with peripheral buffer material, further reduces the pressure between the electric core.

Further, the rigid unit is hollow inside to form a cavity.

By adopting the scheme, the weight of the whole battery cell module can be reduced, and the light weight concept is realized.

Further, the cavity is filled with a fire extinguishing agent.

By adopting the scheme, when the battery cell is out of control due to lithium precipitation caused by extrusion or uneven stress, the fire extinguishing agent of the rigid material can be sprayed out to play a role in extinguishing fire.

Further, the rigid unit is made of metal aluminum, alloy aluminum or low carbon steel, and the surface of the rigid unit is coated with an insulating layer.

By adopting the scheme, the metal aluminum, the alloy aluminum or the low-carbon steel is a good rigid buffer material, and the insulating layer can prevent the short circuit caused by the contact between the battery cell and the metal.

Further, the elastic unit adopts ABS or PMMA.

By adopting the scheme, the rigidity of ABS, PMMA and the like is larger than that of the buffer material, so that the buffer effect is favorably achieved.

Further, the buffer material adopts foam, EVA, aerogel heat insulation pad, silica gel or polyurethane.

By adopting the scheme, the buffer material is softer, can play an anti-buffering role on the battery cell, and improves the safety of the battery cell.

A battery pack includes a housing and a battery module structure located in the housing.

Through adopting above-mentioned scheme, improve the whole circulation ability of battery package, reduce the lithium risk that draws out that the local atress of electric core is uneven leads to the circulation life and the security performance of battery package can also reduce the maintenance cost of battery package simultaneously, and the suppression effect can also be got up to battery package or module shell fracture that the whole inflation of electric core leads to spacing unit in addition, further guarantees the safety of battery package or module.

In summary, the battery module structure and the battery pack provided by the utility model have the following technical effects:

1. By arranging buffer materials with different thickness or density between the thinned battery cells, all points of the battery cells are guaranteed to be stressed nearly uniformly, the phenomenon of local lithium precipitation caused by uneven stress is avoided, and the cycle performance of the battery pack is improved;

2. The flatness of the whole module or the battery pack is improved by adopting buffer materials with different thickness or density, so that the problem of shell cracking caused by local extrusion of the battery pack shell is avoided, and the risk of thermal runaway of the battery pack or the module after extrusion is reduced.

Drawings

Fig. 1 is a schematic diagram of an arrangement structure of a battery module according to an embodiment of the present utility model;

FIG. 2 is a schematic diagram of a limiting unit according to an embodiment of the present utility model;

FIG. 3 is a schematic diagram of an explosion structure of a limiting unit according to an embodiment of the present utility model;

Fig. 4 is a schematic structural diagram of a limiting unit with fire extinguishing agent according to an embodiment of the present utility model.

Wherein the reference numerals have the following meanings: 1. a battery cell; 11. a first expansion surface; 12. a second expansion surface; 13. a cell recess; 14. a cell projection; 2. a buffer material; 21. a first material portion; 22. a second material portion; 3. an end buffer material; 31. leveling the plane; 4. a limit unit; 41. a rigid unit; 411. a support surface; 42. an elastic unit; 421. a connection surface; 422. a bearing surface; 43. a cavity; 5. fire extinguishing agent.

Detailed Description

For a better understanding and implementation, the technical solutions of the embodiments of the present utility model will be clearly and completely described and discussed below in conjunction with the accompanying drawings, and it is apparent that what is described herein is only a part, but not all, of the examples of the present utility model, and all other embodiments obtained by those skilled in the art without making any inventive effort based on the embodiments of the present utility model are within the scope of protection of the present utility model.

For the purpose of facilitating an understanding of the embodiments of the present utility model, reference will now be made to the drawings, by way of example, of specific embodiments, and the various embodiments should not be construed to limit the embodiments of the utility model.

In the description of the present utility model, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, only for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the apparatus or elements to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs. The terminology used herein in the description of the utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model.

Referring to fig. 1-4, the utility model discloses a battery module structure, which comprises a plurality of square battery cells 1 and buffer materials 2 clamped between the battery cells 1, wherein the battery cells 1 are sequentially arranged along the thickness direction of the battery cells 1, each battery cell 1 comprises a first expansion surface 11 and a second expansion surface 12 opposite to the first expansion surface 11, and at least one of the first expansion surface 11 and/or the second expansion surface 12 comprises a flat part and a non-flat part; the buffer material 2 is arranged between every two adjacent cells 1 along the arrangement direction of the cells 1, end buffer materials 3 are arranged outside the two cells 1 positioned at the edge, one side surface of each end buffer material 3, far away from the cell 1, is a flat plane 31, the thickness of each buffer material 2 positioned at the flat part is different from that of the other end buffer material, or the density of each buffer material 2 positioned at the flat part is different from that of the other end buffer material, the adaptation degree with the cell 1 is improved by adopting the buffer material 2 adapted to the surface of the cell 1, the problem of uneven stress between different parts of the cell 1 is reduced, and finally the stress of all the points of the cell 1 is nearly consistent, so that the safety of the cell 1 is improved, the whole cell 1 is in a rectangular structure after being arranged through the end buffer materials 3, and the phenomenon of inclination, protrusion or depression cannot occur.

The buffer material 2 includes, but is not limited to, foam, EVA, aerogel heat insulation pad, silica gel or polyurethane, and the buffer material 2 such as foam, EVA, aerogel heat insulation pad, silica gel or polyurethane is soft, so that the buffer material can play an anti-buffering role on the battery cell 1, and the safety of the battery cell 1 is improved.

In one embodiment, the non-flat portion includes a cell concave portion 13 and/or a cell convex portion 14, the surface of the buffer material 2, which is in contact with the non-flat portion of the cell 1, includes a first material portion 21 corresponding to and attached to the cell concave portion 13 and/or a second material portion 22 corresponding to and attached to the cell convex portion 14, where the thickness of the first material portion 21 > the thickness of the flat portion of the buffer material 2 > the thickness of the second material portion 22, and the buffer material 2 at the position is thinned at the position where the surface of the cell 1 is thicker by designing the buffer material 2 with uneven thickness to compensate for the non-uniformity of the stress on the surface of the cell 1; the buffer material 2 at the position of the thinner surface of the battery cell 1 is thicker; ensuring that all points of the battery cell 1 are stressed nearly uniformly.

In one embodiment, the non-flat part comprises a cell concave part 13 and/or a cell convex part 14, and the surface of the buffer material 2, which is in contact with the non-flat part of the cell 1, comprises a first material part 21 which is correspondingly attached to the cell concave part 13 and/or a second material part 22 which is correspondingly attached to the cell convex part 14, wherein the density of the first material part 21 is greater than the density of the flat part of the buffer material 2 > the density of the second material part 22, and the non-uniformity of the surface stress of the cell 1 is improved by designing the buffer material 2 with non-uniform density. The density of the buffer material 2 at this position is reduced at a thicker surface of the cell 1, and the density of the buffer material 2 is increased at this position at a thinner surface of the cell 1. Eventually, the stress of all points of the battery cell 1 is nearly uniform.

In order to better enhance the compression resistance of the cushioning material 2, in some embodiments, a plurality of limiting units 4 are arranged in the cushioning material 2 at intervals, the limiting units 4 comprise rigid units 41 and elastic units 42, in the thickness direction of the cushioning material 2, the limiting units 4 wrap the rigid units 41 by adopting two elastic units 42 to form a sandwich structure in a hamburger shape, the rigid units 41 are positioned in the center of the cushioning material 2, and two opposite supporting surfaces 411 are arranged along the arrangement direction of the battery cells 1; the elastic unit 42 is connected to the supporting surface 411 of the rigid unit 41, and the limiting unit 4 can further prevent the cell 1 from expanding unevenly. When the battery cell 1 circulates, the expansion of the local position is larger, the shell of the battery cell 1 compresses the buffer material 2 and contacts the limiting unit 4, the extrusion force of the limiting unit 4 to the battery cell 1 is larger than that of the buffer material 2, so that the local position of the battery cell 1 cannot be displaced, and the stress is relatively reduced. The rigidity and the anti-extrusion capability of the elastic unit 42 are better than those of the buffer material 2, so as to play a role in compression resistance, the rigid unit 41 can prevent the local position of the battery cell 1 from being stressed excessively, and rigid buffering is performed, and it should be noted that the elastic unit 42 and the rigid unit 41 include, but are not limited to, adhesive connection, and the embodiment is not limited specifically.

Further, the elastic unit 42 includes a connection surface 421 abutting against the support surface 411 of the rigid unit 41 and a bearing surface 422 opposite to the connection surface 421, the area of the bearing surface 422 is larger than that of the connection surface 421, the width of the elastic unit 42 gradually increases in the direction from the connection surface 421 to the bearing surface 422, in the width direction of the elastic unit 42, the middle part of the bearing surface 422 of the elastic unit 42 protrudes to the side far away from the connection surface 421 to form an arc surface, so that the elastic unit 42 presents an axe shape in the cross-section structure, the elastic unit 42 is located at two sides of the rigid unit 41, the bearing surface 422 contacting the battery core 1 presents a certain amplitude, which is favorable for point contact with the battery core 1, the middle part of the elastic unit 42 presents an arc shape, which can increase contact with the peripheral buffer material 2, and further reduce pressure between the battery cores 1.

In the above embodiment, the rigid unit 41 includes, but is not limited to, metal aluminum, alloy aluminum or low carbon steel, and the surface of the rigid unit 41 is coated with an insulating layer, wherein the metal aluminum, alloy aluminum or low carbon steel is a good rigid buffer material 2, and the insulating layer can prevent the short circuit caused by the contact between the battery cell 1 and the metal. The elastic unit 42 includes, but is not limited to, ABS or PMMA, which have a relatively high rigidity with respect to the cushioning material 2, and thus are advantageous for cushioning. Because the heavy material of the rigid unit 41 affects the overall weight of the battery pack, in some embodiments, the hollow cavity 43 is formed inside the rigid unit 41, so that the weight of the overall battery cell 1 module can be reduced, and the light weight concept can be realized.

In some embodiments, to further prevent the battery cell 1 from fire in thermal runaway, the cavity 43 inside the rigid unit 41 is filled with the fire extinguishing agent 5, and when the battery cell 1 is in thermal runaway caused by lithium precipitation due to extrusion or uneven stress, the fire extinguishing agent 5 of the rigid material can be sprayed out to play a role in extinguishing fire.

The utility model also relates to a battery pack, which comprises a shell and a battery module structure positioned in the shell, so that the overall circulation capacity of the battery pack can be improved, and the lithium precipitation risk caused by uneven local stress of the battery core 1 can be reduced, thereby the cycle life and the safety performance of the battery pack can be reduced, and meanwhile, the maintenance cost of the battery pack can be reduced, in addition, the limit unit 4 can also inhibit the rupture of the battery pack or the module shell caused by the overall expansion of the battery core 1, and the safety of the battery pack or the module can be further ensured.

According to the utility model, control experiments are carried out according to different buffer materials 2, wherein the five groups of materials are adopted, the first group adopts common buffer materials 2, the second group adopts buffer materials 2 with nonuniform thickness, and the buffer materials 2 do not contain a limiting unit 4; the third group adopts buffer materials 2 with nonuniform thickness, and the buffer materials 2 comprise limiting units 4; the fourth group adopts a buffer material 2 with non-uniform density, and the buffer material 2 does not contain a limiting unit 4; the fifth group adopts a buffer material 2 with non-uniform density, the buffer material 2 comprises a limiting unit 4, the five groups of buffer materials 2 are respectively arranged in five battery packs to carry out the cyclic charge and discharge test of the batteries, and the test results are as follows:

According to the table, the third group and the fourth group have more circulation times and the expansion rate of the battery cell 1 is lower, so that the battery cell 1 can be restrained by adopting the buffer material 2 with uneven thickness or the buffer material 2 with uneven density, and meanwhile, the expansion of the battery cell 1 can be restrained by adding the limiting unit 4, and the circulation is increased.

According to the utility model, the fire resistance test is carried out by adopting different buffer materials 2 to form a control experiment, and the first group adopts common buffer materials 2; the second group adopts buffer materials 2 with nonuniform thickness and comprises a common limiting unit 4; the second group adopts buffer materials 2 with nonuniform thickness and comprises a limit unit 4 with fire extinguishing agent 5; five sets of buffer materials 2 were respectively set in five battery packs for thermal runaway test, and the temperature in the battery packs at the time of thermal runaway test was as follows:

According to the table, the temperature of the battery pack can be effectively reduced by the aid of the limiting unit 4, explosion is prevented, the temperature of the battery pack can be reduced to the greatest extent by the aid of the limiting unit 4 with the fire extinguishing agent 5, phenomena such as fire and explosion cannot occur, and safety of the battery pack is greatly improved.

In summary, the battery module structure and the battery pack provided by the utility model have the following technical effects:

1. By arranging the buffer materials 2 with different thickness or density between the thinned battery cells 1, all points of the battery cells 1 are guaranteed to be stressed nearly uniformly, the phenomenon of local lithium precipitation caused by uneven stress is avoided, and the cycle performance of the battery pack is improved;

2. The flatness of the whole module or the battery pack is improved by adopting the buffer material 2 with different thickness or density, so that the problem of shell rupture caused by local extrusion of the battery pack shell is avoided, and the risk of thermal runaway of the battery pack or the module after extrusion is reduced.

The technical means disclosed by the scheme of the utility model is not limited to the technical means disclosed by the embodiment, and also comprises the technical scheme formed by any combination of the technical features. It should be noted that modifications and adaptations to the utility model may occur to one skilled in the art without departing from the principles of the present utility model and are intended to be within the scope of the present utility model.

Claims (16)

1. A battery module structure, comprising:

The battery cells (1) are sequentially arranged along the thickness direction of the battery cells (1), each battery cell (1) comprises a first expansion surface (11) and a second expansion surface (12) opposite to the first expansion surface (11), and at least one of the first expansion surfaces (11) and/or the second expansion surfaces (12) comprises a flat part and a non-flat part;

The buffer material (2), the buffer material (2) is arranged between every two adjacent electric cores (1) along the arrangement direction of the electric cores (1), the thickness of the buffer material (2) positioned at the flat part is different from the thickness of the non-flat part, or the density of the buffer material (2) positioned at the flat part is different from the density of the non-flat part.

2. The battery module structure according to claim 1, wherein end buffer materials (3) are arranged on the outer sides of two battery cells (1) positioned at the edge in the arrangement direction of the battery cells (1), and the surface of one side of the end buffer materials (3) away from the battery cells (1) is a flat plane (31).

3. A battery module structure according to claim 1 or 2, characterized in that the non-flat part comprises a cell recess (13) and/or a cell protrusion (14).

4. A battery module structure according to claim 3, wherein the surface of the buffer material (2) contacting the non-flat portion of the battery cell (1) comprises a first material portion (21) corresponding to the concave portion (13) of the battery cell and/or a second material portion (22) corresponding to the convex portion (14) of the battery cell, wherein the thickness of the first material portion (21) is greater than the thickness of the flat portion of the buffer material (2) is greater than the thickness of the second material portion (22).

5. A battery module structure according to claim 3, characterized in that the surface of the buffer material (2) contacting the non-flat part of the battery cell (1) comprises a first material part (21) corresponding to the concave part (13) of the battery cell and/or a second material part (22) corresponding to the convex part (14) of the battery cell, wherein the density of the first material part (21) is greater than the density of the flat part of the buffer material (2) > the density of the second material part (22).

6. The battery module structure according to claim 4 or 5, wherein a plurality of limiting units (4) are arranged in the buffer material (2) at intervals, and the limiting units (4) comprise:

The rigid unit (41) is positioned in the center of the buffer material (2), and comprises two opposite supporting surfaces (411) along the arrangement direction of the battery cells (1);

-an elastic unit (42), said elastic unit (42) being connected to a supporting surface (411) of said rigid unit (41).

7. The battery module structure according to claim 6, wherein the elastic unit (42) includes a connection surface (421) abutting against the support surface (411) of the rigid unit (41) and a receiving surface (422) opposite to the connection surface (421).

8. The battery module structure according to claim 7, wherein the support surface (422) has an area larger than that of the connection surface (421).

9. The battery module structure according to claim 7, wherein the width of the elastic unit (42) is gradually increased in the direction from the connection surface (421) to the support surface (422).

10. The battery module structure according to claim 7, wherein the middle portion of the support surface (422) of the elastic unit (42) protrudes to a side away from the connection surface (421) in the width direction of the elastic unit (42) to form an arc surface.

11. A battery module structure according to any one of claims 7-10, wherein the rigid unit (41) is internally hollow to form a cavity (43).

12. The battery module structure according to claim 11, wherein the cavity (43) is filled with a fire extinguishing agent (5).

13. The battery module structure according to claim 11, wherein the rigid unit (41) is made of metal aluminum, alloy aluminum or low carbon steel, and the surface of the rigid unit (41) is coated with an insulating layer.

14. The battery module structure according to claim 11, wherein the elastic unit (42) is ABS or PMMA.

15. The battery module structure according to claim 11, wherein the buffer material (2) is foam, EVA, aerogel insulation mat, silica gel or polyurethane.

16. A battery pack comprising a case and a battery module structure according to any one of claims 1 to 15 in the case.