Battery cell and lithium battery

Abstract

The utility model discloses a battery cell and a lithium battery, the battery cell comprises an anode plate, a cathode plate and a diaphragm arranged between the anode plate and the cathode plate, and the anode plate, the diaphragm and the cathode plate are sequentially stacked and wound to form the battery cell; the cathode plate comprises a pre-rolling part and a rolling part connected with the pre-rolling part, the pre-rolling part is used for wrapping the starting end of the cathode plate so as to isolate the starting end of the cathode plate from the diaphragm, and the rolling part is used for rolling with the anode plate and the diaphragm to form a battery cell. According to the technical scheme, the cathode piece comprises the pre-rolling part and the rolling part connected with the pre-rolling part, the pre-rolling part is used for wrapping the starting end of the cathode piece so that the starting end of the cathode piece can be isolated from the diaphragm, and therefore the situation that burrs at the starting end of the cathode piece pierce the diaphragm, and consequently the anode piece makes direct contact with the cathode piece is avoided; therefore, the safety risk caused by short circuit in the battery cell is reduced, the anti-extrusion capability of the battery cell is enhanced, and the safety of the battery cell is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, and particularly relates to a battery cell and a lithium battery. Background Art

[0002] A lithium battery refers to a lithium-ion battery containing lithium (including metallic lithium, lithium alloy, lithium ions, and lithium polymers) in an electrochemical system. In recent years, due to its many advantages such as long cycle life, good safety performance, and fast charge and discharge, lithium batteries have been widely used in fields such as digital products, electric vehicles, and energy storage systems.

[0003] Currently, in the lithium battery industry, an anode sheet, a cathode sheet, and a separator are generally made into a wound battery cell by winding. The head structure of the existing wound battery cell is usually that the anode sheet is directly inserted into the cathode sheet after pre-winding. The head of the cathode sheet is generally a foil area or a material area, and burrs are likely to be generated at the position where it is inserted into the cathode sheet after cutting. When the wound battery cell is subjected to abnormal conditions such as collision or extrusion, the burrs at the cutting position are likely to pierce the separator, resulting in direct contact between the anode sheet and the cathode sheet inside the battery cell, thus causing internal short circuit of the battery cell and affecting the safe use of the battery cell. Summary of the Utility Model

[0004] The main purpose of the utility model is to propose a battery cell and a lithium battery, aiming to solve the technical problem that the existing battery cell is prone to internal short circuit caused by burrs piercing the separator.

[0005] To achieve the above object, the utility model proposes a battery cell, which includes an anode sheet, a cathode sheet, and a separator disposed between the anode sheet and the cathode sheet. The anode sheet, the separator, and the cathode sheet are stacked and wound in sequence to form the battery cell.

[0006] Wherein, the cathode sheet includes a pre-wound part and a wound part connected to the pre-wound part. The pre-wound part is used to wrap the starting end of the cathode sheet to isolate the starting end of the cathode sheet from the separator, and the wound part is used to wind with the anode sheet and the separator to form the battery cell.

[0007] In some embodiments, the pre-wound part includes a first pre-wound segment and at least one second pre-wound segment connected in sequence along the winding direction. The free end of the first pre-wound segment is the starting end of the cathode sheet, and the at least one second pre-wound segment is connected to the starting segment of the wound part of the cathode sheet. Along the thickness direction of the battery cell, the first pre-wound segment is located between the second pre-wound segment and the starting segment of the wound part.

[0008] In some embodiments, there is one second pre-wound segment. Along the thickness direction of the battery cell, the second pre-wound segment is located between the starting segment of the anode sheet winding and the first pre-wound segment.

[0009] In some embodiments, along the length direction of the cathode sheet, both the upper and lower surfaces of the first pre-rolled section are empty foil structures.

[0010] In some embodiments, along the thickness direction of the battery cell, one side portion of the second pre-rolled section close to the winding starting section of the anode sheet is provided with an active material layer.

[0011] In some embodiments, there are two second pre-rolled sections. Along the thickness direction of the battery cell, one of the second pre-rolled sections is located between the winding starting section of the anode sheet and the first pre-rolled section, and the other second pre-rolled section is located between the first pre-rolled section and the winding starting section of the winding part.

[0012] In some embodiments, there are three second pre-rolled sections. Along the thickness direction of the battery cell, two of the second pre-rolled sections are respectively located between the winding starting section of the anode sheet and the first pre-rolled section, and the other second pre-rolled section is located between the first pre-rolled section and the winding starting section of the winding part.

[0013] In some embodiments, a bent connection section is provided between the pre-rolled part and the winding part, and there is a preset distance from the starting end of the anode sheet to the bent connection section.

[0014] In some embodiments, the preset distance is greater than or equal to 0.2 mm.

[0015] The present utility model also provides a lithium battery, including a housing and the battery cell as described above, and the battery cell is arranged inside the housing.

[0016] In the technical solution of the present application, the cathode sheet includes a pre-rolled part and a winding part connected to the pre-rolled part. The pre-rolled part is used to wrap the starting end of the cathode sheet so as to isolate the starting end of the cathode sheet from the separator, thereby avoiding the burrs at the starting end of the cathode sheet from piercing the separator and causing direct contact between the anode sheet and the cathode sheet, and further reducing the safety risk caused by internal short circuit of the battery cell, enhancing the anti-extrusion ability of the battery cell, and improving the safety of the battery cell. Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of an embodiment of the battery cell of the present utility model;

[0018] Figure 2 It is a partial structural diagram of an embodiment of the battery cell of the present utility model.

[0019] Explanation of the Reference Numerals in the Drawings:

[0020]

[0021]

[0022] The realization, functional features and advantages of the present utility model will be further described with reference to the embodiments and the accompanying drawings. Specific embodiments

[0023] The following will clearly and completely describe the solutions in the embodiments of the present utility model 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 of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0024] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present utility model are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0025] It should also be noted that when an element is referred to as "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 "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0026] In addition, the descriptions involving "first", "second", etc. in the present utility model are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, 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 them. When the combination of technical solutions is contradictory 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 utility model.

[0027] Before the battery core is wound, the cathode sheet is usually cut off by a cutting knife. During this process, burrs are likely to be generated at the starting end of the cathode sheet. These burrs are likely to pierce the separator and cause the anode sheet inside the battery core to come into direct contact with the cathode sheet 20, thereby causing a short circuit inside the battery core.

[0028] To avoid the burrs on the cathode sheet from piercing the separator and causing a short circuit inside the battery core, please refer to Figure 1 and Figure 2, an embodiment of the present application provides a battery cell 100, which includes an anode sheet 10, a cathode sheet 20, and a separator 30 disposed between the anode sheet 10 and the cathode sheet 20. The anode sheet 10, the separator 30, and the cathode sheet 20 are stacked and wound in sequence to form the battery cell 100. Among them, the cathode sheet 20 includes a pre-wound portion 21 and a wound portion 22 connected to the pre-wound portion 21. The wound portion 22 is used to wind with the anode sheet 10 and the separator 30 to form the battery cell 100, and the pre-wound portion 21 is used to wrap the starting end 201 of the cathode sheet to isolate the starting end 201 of the cathode sheet from the separator 30.

[0029] When the battery cell 100 is subjected to collision or extrusion, the starting end 201 of the cathode sheet contacts the pre-wound portion 21 of the cathode sheet 20, thereby preventing the burrs at the starting end 201 of the cathode sheet from piercing the separator 30 and causing direct contact between the anode sheet 10 and the cathode sheet 20. Furthermore, it reduces the safety risk caused by internal short circuit of the battery cell 100, enhances the anti-extrusion ability of the battery cell 100, and improves the safety of the battery cell 100.

[0030] In this embodiment, before the battery cell 100 is wound, the anode sheet 10 is inserted into a winding needle for pre-winding. At the same time, the cathode sheet 20 is inserted into another winding needle for pre-winding. After pre-winding, the cathode sheet 20 completely wraps the burrs at the starting end 201 of the cathode sheet inside. Then the winding needle is pulled out, and the pre-wound cathode sheet 20 is inserted into the winding needle of the pre-wound anode sheet 10 for winding.

[0031] In some embodiments, please continue to refer to Figure 2 , the pre-wound portion 21 includes a first pre-wound segment 211 and at least one second pre-wound segment 212 connected in sequence along the winding direction. The free end of the first pre-wound segment 211 is the starting end 201 of the cathode sheet, and at least one second pre-wound segment 212 is connected to the starting segment 101 of the wound portion 22 of the battery cell 100. Along the thickness direction of the battery cell 100, the first pre-wound segment 211 is located between the second pre-wound segment 212 and the starting segment 101 of the wound portion 22.

[0032] In this embodiment, the second pre-wound segment 212 separates the first pre-wound segment 211 from the separator 30, and the free end of the first pre-wound segment 211 is the starting end 201 of the cathode sheet. Therefore, the setting of the second pre-wound segment 212 can reduce the probability that the burrs at the starting end 201 of the cathode sheet pierce the separator 30 and cause direct contact between the anode sheet 10 and the cathode sheet 20, thereby reducing the safety risk caused by short circuit of the battery cell 100.

[0033] As the first embodiment, there is one second pre-wound segment 212. Along the thickness direction of the battery cell 100, the second pre-wound segment 212 is located between the starting segment 101 of the anode sheet 10 and the first pre-wound segment 211. In this embodiment, the number of the second pre-wound segments 212 is the least, and the influence on the thickness of the battery cell 100 is the smallest.

[0034] In some embodiments, along the length direction of the cathode sheet 20, both the upper and lower surfaces of the first pre-rolling section 211 are empty foil structures, which can enhance the mechanical support for the first pre-rolling section 211.

[0035] In some embodiments, along the thickness direction of the battery cell 100, on one side of the second pre-rolling section 212 close to the winding starting section 101 of the anode sheet 10, an active material layer is provided.

[0036] As a second embodiment, two second pre-rolling sections 212 are provided. Along the thickness direction of the battery cell 100, one of the second pre-rolling sections 212 is located between the winding starting section 101 of the anode sheet 10 and the first pre-rolling section 211, and the other second pre-rolling section 212 is located between the first pre-rolling section 211 and the winding starting section 101 of the winding part 22.

[0037] As a third embodiment, three second pre-rolling sections 212 are provided. Along the thickness direction of the battery cell 100, two of the second pre-rolling sections 212 are respectively located between the winding starting section 101 of the anode sheet 10 and the first pre-rolling section 211, and the other second pre-rolling section 212 is located between the first pre-rolling section 211 and the winding starting section 101 of the winding part 22.

[0038] In this embodiment, two second pre-rolling sections 212 are provided between the first pre-rolling section 211 and the winding starting section 101 of the anode sheet 10, which increases the thickness of the pre-rolling part 21 covering the starting end 201 of the cathode sheet, thereby further reducing the probability that the burr at the starting end 201 of the cathode sheet pierces the separator 30 and causes direct contact between the anode sheet 10 and the cathode sheet 20.

[0039] In some embodiments, a bent connecting section 23 is provided between the pre-rolling part 21 and the winding part 22. There is a preset distance D from the starting end 102 of the anode sheet to the bent connecting section 23, and the preset distance D is greater than or equal to 0.2 mm.

[0040] The present utility model also provides a lithium battery, including a housing and the battery cell 100 as described above, and the battery cell 100 is disposed in the housing. Since all the technical solutions of all the embodiments of the above battery cell 100 are adopted, the lithium battery of the present utility model at least has all the technical effects brought by the technical solutions of the above embodiments of the battery cell 100, which will not be elaborated herein one by one.

[0041] The above embodiments of the present utility model are merely examples for clearly illustrating the present utility model, rather than limitations on the implementation manners of the present utility model. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present utility model still fall within the protection scope of the present utility model.

Claims

1. A battery cell, characterized in that: The battery cell comprises an anode sheet, a cathode sheet and a separator disposed between the anode sheet and the cathode sheet, wherein the anode sheet, the separator and the cathode sheet are sequentially stacked and wound to form the battery cell; Among them, the cathode sheet includes a pre-rolled part and a winding part connected to the pre-rolled part, the pre-rolled part is used to cover the starting end of the cathode sheet to isolate the starting end of the cathode sheet from the diaphragm, and the winding part is used to be wound with the anode sheet and the diaphragm to form the battery cell.

2. The battery cell according to claim 1, characterized in that: The pre-rolled portion includes a first pre-rolled segment and at least one second pre-rolled segment connected in sequence along the winding direction, the free end of the first pre-rolled segment is the starting end of the cathode sheet, and the at least one second pre-rolled segment is connected to the winding starting segment of the winding portion, and along the thickness direction of the battery cell, the first pre-rolled segment is located between the second pre-rolled segment and the winding starting segment of the winding portion.

3. The battery cell according to claim 2, characterized in that: The second pre-rolling section is provided with one, and along the thickness direction of the battery cell, the second pre-rolling section is located between the winding start section of the anode sheet and the first pre-rolling section.

4. The battery cell according to claim 3, characterized in that: Along the length direction of the cathode sheet, both upper and lower surfaces of the first pre-rolled section are hollow foil structures.

5. The battery cell according to claim 4, characterized in that: Along the thickness direction of the battery cell, an active material layer is provided on a side portion of the second pre-rolled section close to the winding start section of the anode sheet.

6. The battery cell according to claim 2, characterized in that: There are two second pre-rolled sections. Along the thickness direction of the battery cell, one of the second pre-rolled sections is located between the winding start section of the anode sheet and the first pre-rolled section, and the other second pre-rolled section is located between the first pre-rolled section and the winding start section of the winding part.

7. The battery cell according to claim 2, characterized in that: There are three second pre-roll segments, along the thickness direction of the battery cell, two of which are located between the winding start segment of the anode sheet and the first pre-roll segment, and another second pre-roll segment is located between the first pre-roll segment and the winding start segment of the winding part.

8. The battery cell according to any one of claims 1 to 7, characterized in that: A bending connection section is provided between the pre-rolling part and the winding part, and a preset distance exists between the starting end of the anode sheet and the bending connection section.

9. The battery cell according to claim 8, characterized in that: The preset distance is greater than or equal to 0.2 mm.

10. A lithium battery, characterized in that: The invention comprises a shell and a battery cell as claimed in any one of claims 1 to 9, wherein the battery cell is arranged in the shell.

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