Battery cell assembly and single battery

Abstract

The utility model discloses a battery cell assembly and a single battery. The battery cell assembly comprises a pole piece, a diaphragm and a pole lug, the pole piece comprises a first end and a second end which are opposite; the diaphragms are arranged on two opposite side surfaces of the pole piece; the tab is arranged at the first end and electrically connected with the pole piece, and the tab is arranged between the pole piece and the diaphragm; wherein the area, corresponding to the first end, of the diaphragm is thickened, the thickened area of the diaphragm is opposite to the tab, and the battery cell assembly is used for winding from the first end to the second end. According to the utility model, the diaphragm at the first end is thickened, so that the thickness of the diaphragm is locally increased to achieve the purpose of reinforcing the diaphragm, the thickness of the rest part of the diaphragm is not changed, and the normal winding process of the diaphragm is not influenced; the thickened area of the diaphragm is opposite to the tab, so that the diaphragm area in direct contact with the tab is thickened in the winding process of the battery cell assembly and when the battery cell assembly is pressed, the tab cannot easily pierce the diaphragm, and the short circuit phenomenon is effectively prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of battery cell assemblies, in particular to a battery cell assembly and a single battery cell. Background Art

[0002] In order to reduce the internal resistance of a cylindrical lithium-ion battery, a structure with multiple tabs is often designed. Usually, there is a tab at each end of the negative electrode tab head to increase the current transmission channel and reduce the internal resistance of the battery. Since the winding diameter of the core part is small and the winding curvature of the core part tab is large, when the battery cell is impacted by an external object, such as in a heavy object impact test, the core part tab is squeezed, and the part where the edge contacts the separator is easily cut through the separator, resulting in an internal short circuit between the positive and negative electrodes of the battery and the risk of battery fire and explosion. Summary of the Utility Model

[0003] An object of the utility model is to provide a battery cell assembly and a single battery cell, aiming to solve the technical problem of short circuit of the battery cell assembly.

[0004] To achieve the above object, a solution provided by the utility model is: a battery cell assembly, which includes a pole piece, a separator, and a tab; the pole piece includes opposite first and second ends; the separator is disposed on opposite side surfaces of the pole piece; the tab is disposed at the first end and electrically connected to the pole piece, and the tab is between the pole piece and the separator; wherein, the area of the separator corresponding to the first end is thickened, the thickened area of the separator faces the tab, and the battery cell assembly is used for winding from the first end to the second end.

[0005] Optionally, the separator includes a connected base part and a strengthening part, the strengthening part is located at the first end and disposed on opposite sides of the first end, the thickness of the strengthening part is D1, the thickness of the base part is D2, and 2 ≤ D1 / D2 ≤ 3.

[0006] Optionally, the separator further includes a transition part, the base part and the strengthening part are connected through the transition part, and in the direction from the base part to the strengthening part, the thickness of the transition part gradually increases.

[0007] Optionally, a fillet is provided at the connection between the transition part and the strengthening part; and / or, a fillet is provided at the connection between the transition part and the base part.

[0008] Optionally, the separator has a uniform thickness, and the separator located at the first end is folded.

[0009] Optionally, the number of times the separator is folded is N, and 1 ≤ N ≤ 3.

[0010] Optionally, the battery cell assembly further includes an adhesive layer, and the tab is adhered to the separator through the adhesive layer.

[0011] Optionally, the battery cell assembly further includes a coating layer, and the coating layer is disposed in the area of the separator corresponding to the first end.

[0012] Optionally, the area of the thickened region of the separator is S1, and the area of the tab is S2, where 3 ≤ S1 / S2 ≤ 8.

[0013] To achieve the above object, a solution provided by the present utility model is: a single cell, which includes: a housing and a battery cell assembly as described in any one of the above, and the battery cell assembly is placed in the housing.

[0014] The beneficial effects of the present utility model are as follows:

[0015] The electrode plate includes opposite first and second ends, and the first and second ends are located at the head and tail positions of the electrode plate in the length direction; the separator is disposed on opposite side surfaces of the electrode plate, and the separator is located in the thickness direction of the electrode plate; the tab is disposed at the first end and electrically connected to the electrode plate, the tab is located at the first end of the electrode plate, and the tab is between the electrode plate and the separator. After assembly, the battery cell assembly is wound from the first end to the second end to form a cylindrical shape, and the tab located at the first end is at the center position of the cylinder; wherein, the separator at the first end is thickened to increase the local thickness of the separator to achieve the purpose of strengthening the separator, and the thickened region of the separator is opposite to the tab to prevent the tab from piercing the separator.

[0016] By thickening the separator at the first end, the thickness of the separator is locally enhanced, and the thickness of the remaining part of the separator remains unchanged, so as not to affect the normal winding process of the separator. The thickened region of the separator is opposite to the tab, so that during the winding process of the battery cell assembly and when the battery cell assembly is under pressure, the separator directly contacted by the tab is thickened, so the tab will not easily pierce the separator, thus effectively preventing the occurrence of short-circuit phenomena. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0018] Figure 1 is a schematic structural diagram of the first embodiment of the battery cell assembly provided by the embodiment of the present utility model;

[0019] Figure 2 is a schematic structural diagram of the second embodiment of the battery cell assembly provided by the embodiment of the present utility model;

[0020] Figure 3 is a schematic structural diagram of the third embodiment of the battery cell assembly provided by the embodiment of the present utility model;

[0021] Figure 4It is a schematic structural diagram of the battery cell assembly provided by the embodiment of the present utility model in a wound state;

[0022] Figure 5 It is a schematic structural diagram of the fourth embodiment of the battery cell assembly provided by the embodiment of the present utility model.

[0023] Explanation of the reference numerals in the drawings:

[0024] Pole piece 10, first end 12, second end 14, separator 20, base portion 21, reinforcing portion 22

[0025] Transition portion 23, rounded corner 24, tab 30, adhesive layer 40, coating layer 50. Detailed implementation manners

[0026] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

[0027] Please refer to Figures 1 to 4 as shown in Figure 1 It is a schematic structural diagram of the first embodiment of the battery cell assembly provided by the embodiment of the present utility model, Figure 2 It is a schematic structural diagram of the second embodiment of the battery cell assembly provided by the embodiment of the present utility model, Figure 3 It is a schematic structural diagram of the third embodiment of the battery cell assembly provided by the embodiment of the present utility model, Figure 4 It is a schematic structural diagram of the battery cell assembly provided by the embodiment of the present utility model in a wound state.

[0028] The present utility model provides a battery cell assembly, which includes a pole piece 10, a tab 30 and a separator 20. The tab 30 is disposed on the pole piece 10 and electrically connected to the pole piece 10. The pole piece 10 is divided into a positive pole piece 10 and a negative pole piece 10. A positive tab 30 is disposed on the positive pole piece 10, and a negative tab 30 is disposed on the negative pole piece 10. The separator 20 is disposed on both side surfaces of the pole piece 10. The separator 20 is mainly used to separate the positive pole piece 10 and the negative pole piece 10 to prevent the positive pole piece 10 and the negative pole piece 10 from directly contacting and causing a short circuit. During the manufacturing process, the positive pole piece 10, the separator 20, and the negative pole piece 10 are stacked in sequence and wound into a shape along a fixed direction.

[0029] The electrode tab 10 includes opposite first end 12 and second end 14, and the first end 12 and the second end 14 are located at the head and tail parts of the electrode tab 10 in the length direction; the separator 20 is disposed on opposite side surfaces of the electrode tab 10, and the separator 20 is located in the thickness direction of the electrode tab 10; the tab 30 is disposed at the first end 12 and electrically connected to the electrode tab 10, the tab 30 is located at the head end of the electrode tab 10, and the tab 30 is between the electrode tab 10 and the separator 20. After assembly, the battery cell assembly is wound from the first end 12 to the second end 14 to form a cylindrical shape, and the tab 30 located at the first end 12 is at the center position of the cylinder; wherein, the area of the separator 20 corresponding to the first end 12 is thickened to increase the local thickness so as to achieve the purpose of strengthening the separator 20. The thickened area of the separator 20 faces the tab 30 to prevent the tab 30 from piercing the separator 20.

[0030] In this embodiment, by thickening the separator 20 located at the first end 12, the strength of the separator 20 is locally enhanced, and the thickness of the rest of the separator 20 remains unchanged, so as not to affect the normal winding process of the separator 20. The thickened area of the separator 20 faces the tab 30, so that during the winding process of the battery cell assembly and when the battery cell assembly is under pressure, the separator 20 directly contacted by the tab 30 is thickened, so the tab 30 will not easily pierce the separator 20, thus effectively preventing the occurrence of short circuit.

[0031] Please refer to Figure 1 , Figure 1 The local thickening is achieved by setting the separator 20 to have different thicknesses. The separator 20 includes a connected base part 21 and a strengthening part 22. The strengthening part 22 is located at the first end 12 and is disposed on opposite two side surfaces of the first end 12. The base part 21 is located outside the first end 12. The separator 20 has an uneven thickness, that is, the thicknesses at different positions of the separator 20 are different. The strengthening part 22 and the base part 21 have their respective thicknesses. The thickness of the strengthening part 22 is D1, and the thickness of the base part 21 is D2, and 2 ≤ D1 / D2 ≤ 3. D1 / D2 can be 2, 2.2, 2.5, 2.8, 3, etc. The thickness of the strengthening part 22 is between 2 times and 3 times the thickness of the base part 21. Within this range, the thickness of the strengthening part 22 and the base part 21 of the separator 20 is just right, that is, it will not increase the winding difficulty of the battery cell assembly at the base part 21, and the tab 30 will not pierce the separator 20 at the position of the strengthening part 22. Therefore, both the manufacturing cost of the separator 20 and the manufacturing difficulty of the battery cell assembly are balanced. In addition, the difference in thickness between the strengthening part 22 and the base part 21 is just right, avoiding the risk of large step difference and causing unevenness or even breakage of the separator 20 during the winding process.

[0032] Please refer to Figure 5 , Figure 5This is a schematic structural diagram of the fourth embodiment of the battery cell assembly provided by the embodiments of the present utility model. The difference between the fourth embodiment and the first embodiment is that the separator 20 further includes a transition portion 23, and the base portion 21 and the reinforcing portion 22 are connected through the transition portion 23. In the direction from the base portion 21 to the reinforcing portion 22, the thickness of the transition portion 23 gradually increases. The thickness at the connection position between the transition portion 23 and the reinforcing portion 22 can be the same as the thickness of the reinforcing portion 22, and the thickness at the connection position between the transition portion 23 and the base portion 21 can be the same as the thickness of the base portion 21. The transition portion 23 smoothly connects the base portion 21 and the reinforcing portion 22, effectively avoiding the situation that the separator 20 breaks during the bending process and the unevenness of the separator 20 during the winding process caused by the large step difference between the base portion 21 and the reinforcing portion 22.

[0033] Furthermore, a chamfer can be provided at the connection between the transition portion 23 and the reinforcing portion 22. The chamfer is an arc structure, which can replace the sharp corner structure at the connection between the transition portion 23 and the reinforcing portion 22. On the one hand, it can reduce the damage to the separator 20 caused by the sharp corner, and on the other hand, it can also make the transition between the transition portion 23 and the reinforcing portion 22 smooth, thereby reducing the risk of the separator 20 being broken during the winding process. The size of the chamfer is based on the smooth transition between the transition portion 23 and the reinforcing portion 22.

[0034] A chamfer is provided at the connection between the transition portion 23 and the base portion 21. The chamfer is an arc structure, which can replace the sharp corner structure at the connection between the transition portion 23 and the base portion 21. On the one hand, it can reduce the damage to the separator 20 caused by the sharp corner, and on the other hand, it can also make the transition between the transition portion 23 and the base portion 21 smooth, thereby reducing the risk of the separator 20 being broken during the winding process. The size of the chamfer is based on the smooth transition between the transition portion 23 and the base portion 21.

[0035] In one embodiment, the battery cell assembly further includes an adhesive layer 40, and the tab 30 is bonded to the separator 20 through the adhesive layer 40. The adhesive layer 40 has adhesiveness, so it has a certain fixing effect. The adhesive layer 40 can ensure that even if the battery cell assembly shakes, the tab 30 and the reinforcing portion 22 of the separator 20 can always be connected together, and the tab 30 and the reinforcing portion 22 maintain the initial relative mounting position. The adhesive layer 40 also has a thickness, so it has a certain strength and can resist a certain degree of puncture pressure of the tab 30 to reduce the puncture pressure transmitted to the reinforcing portion 22, thereby further strengthening the blocking strength near the tab 30.

[0036] Please refer to Figure 2 , Figure 2It is a way to achieve local thickening by folding the separator 20 to form different thicknesses. Compared with the first embodiment, the biggest difference in the second embodiment is that the thickness of the separator 20 in this embodiment is uniformly unchanged. In this embodiment, the separator 20 is thickened at the first end 12 by folding the separator 20. Specifically, the separator 20 is folded and stacked together along the thickness direction of the separator 20. Each time the separator 20 is folded, it is stacked once, and the thickness is correspondingly increased by the thickness of one separator 20. The advantage of this embodiment is that it does not change the thickness of the separator 20 itself. Only the separator 20 with a standard thickness needs to be purchased. The separator 20 at the first end 12 is folded a preset number of times before winding. Therefore, not only can the procurement cost be reduced, but also the separator 20 materials of other products can be shared.

[0037] According to the actual strength requirements, the number of folds is N, 1 ≤ N ≤ 3. It can be folded once, twice, or three times. The more times it is folded, the greater the thickness of the separator 20 at the first end 12, but it will also cause the thickness imbalance between the separator 20 at the first end 12 and the remaining separators 20. During the winding process, the overall separator 20 is not balanced enough. Within the range of 1 to 3 times mentioned above, both the strength requirements of the separator 20 at the first end 12 and the flatness of the separator 20 during the winding process can be ensured.

[0038] In one embodiment, the battery cell assembly further includes an adhesive layer 40. The tab 30 is bonded to the separator 20 through the adhesive layer 40. The adhesive layer 40 has adhesiveness, so it has a certain fixing effect. The adhesive layer 40 can ensure that even if the battery cell assembly shakes, the tab 30 and the stacked separators 20 can always be connected together. The tab 30 and the stacked separators 20 maintain the initial relative installation positions, and the stacked separators 20 will not return to their original state due to their own elasticity. The adhesive layer 40 also has a thickness, so it has a certain strength and can resist a certain degree of puncture pressure of the tab 30 to reduce the puncture pressure transmitted to the stacked separators 20, thereby further strengthening the blocking strength near the tab 30.

[0039] Please refer to Figure 3 , Figure 3 It is a way to achieve local thickening by folding the separator 20 to form different thicknesses. Compared with the second embodiment, the biggest difference in the third embodiment is that in this embodiment, a coating layer 50 is provided on the separator 20 to form different thicknesses to achieve local thickening. The battery cell assembly further includes a coating layer 50. The coating layer 50 is provided in the area of the separator 20 corresponding to the first end 12. The coating layer 50 is provided on at least one side of the first end 12 and can be located on one side or on two opposite sides. Figure 3The coating layer 50 shown is located on two opposite sides of the separator 20. The coating layer 50 can be a material with a greater hardness than the separator 20, such as a plastic sheet or a metal sheet. In this way, for the same thickness, the coating layer 50 has a greater hardness than the separator 20 and is thus less likely to be punctured. The coating layer 50 can also be a UV glue. After being coated on the separator 20 and solidifying, a hard layer will be formed on the separator 20. The advantage of this embodiment compared with the first embodiment is that without changing the thickness of the separator 20 itself, only a separator 20 with a standard thickness needs to be purchased. The coating layer 50 is provided on the separator 20 at the first end 12 before winding. Therefore, not only can the procurement cost be reduced, but also the separator 20 materials of other products can be shared.

[0040] Further, the area of the thickened region of the separator 20 is S1, and the area of the tab 30 is S2. 3 ≤ S1 / S2 ≤ 8. S1 / S2 can be 3, 4, 5, 6, 7, 8, etc. The area S1 is 3 to 8 times the area S2. Within this range, the thickened region of the separator 20 can completely cover the tab 30. Additionally, it can also prevent the tab 30 from moving beyond the thickened region of the separator 20.

[0041] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If this specific posture changes, then the directional indication will also change accordingly.

[0042] It also should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or it can also be indirectly connected to the other element through an intermediate element.

[0043] In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of such features. Additionally, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0044] The above are only the preferred embodiments of the present utility model, and do not limit the patent scope of the present utility model accordingly. Any equivalent structural transformation made under the inventive concept of the present utility model by using the content of the specification and drawings of the present utility model, or any direct / indirect application in other related technical fields shall be included within the patent protection scope of the present utility model.

Claims

1. A battery cell assembly, characterized in that, Comprising: A pole piece, including opposite first and second ends; A separator, disposed on opposite side surfaces of the pole piece; And A tab, disposed at the first end and electrically connected to the pole piece, the tab being between the pole piece and the separator; Wherein, a region of the separator corresponding to the first end is thickened, the thickened region of the separator faces the tab, and the cell assembly is configured to be wound from the first end towards the second end.

2. The cell assembly according to claim 1, wherein The separator includes a connected base portion and a reinforcing portion, the reinforcing portion is disposed on opposite sides of the first end at the first end, the thickness of the reinforcing portion is D1, the thickness of the base portion is D2, and 2 ≤ D1 / D2 ≤ 3.

3. The battery cell assembly according to claim 2, wherein, The separator further includes a transition portion, the base portion and the reinforcing portion are connected by the transition portion, and in the direction from the base portion to the reinforcing portion, the thickness of the transition portion gradually increases.

4. The cell assembly according to claim 3, wherein, A fillet is provided at the connection between the transition portion and the reinforcing portion; and / or, a fillet is provided at the connection between the transition portion and the base portion.

5. The cell assembly according to claim 1, wherein The separator has a uniform thickness, and the separator at the first end is folded.

6. The cell assembly according to claim 5, wherein The number of times the separator is folded is N, and 1 ≤ N ≤ 3.

7. The battery cell assembly according to any one of claims 1 to 6, characterized in that, The cell assembly further includes an adhesive layer, and the tab is adhered to the separator through the adhesive layer.

8. The battery cell assembly according to claim 1, wherein The cell assembly further includes a coating layer, and the coating layer is disposed on the region of the separator corresponding to the first end.

9. The cell assembly according to claim 1, characterized in that, The area of the thickened region of the separator is S1, the area of the tab is S2, and 3 ≤ S1 / S2 ≤ 8.

10. A single cell, characterized in that, The single cell includes: a housing and the cell assembly according to any one of claims 1 to 9, and the cell assembly is placed in the housing.

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