Battery cell and lithium ion battery

Abstract

The utility model discloses a battery cell and a lithium ion 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; a straight part and a bent part are formed in each winding ring formed by winding the anode plate, the cathode plate and the diaphragm; wherein the cathode piece comprises a thinned section and an equal-thickness section, the thinned section and the equal-thickness section are alternately connected in the winding direction of the cathode piece, the thickness of the thinned section is smaller than that of the equal-thickness section, the thinned section in each winding ring is located in the bent part of the corresponding winding ring, and the equal-thickness section in each winding ring is located in the straight part of the corresponding winding ring. Therefore, a gap is formed between the thinned section of the cathode piece and the anode piece when the cathode piece and the anode piece are wound, so that excessive extrusion of the cathode piece and the anode piece can be relieved, the storage of electrolyte is facilitated, and the probability of lithium precipitation of the bending part of the battery cell in the subsequent charging and discharging circulation process is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium ion batteries, in particular to a battery core and a lithium ion battery. Background Art

[0002] Lithium-ion batteries refer to lithium-ion batteries that contain lithium (including metallic lithium, lithium alloys, lithium ions, and lithium polymers) in their electrochemical systems. In recent years, lithium-ion batteries have been widely used in digital products, electric vehicles, energy storage systems, and other fields due to their many advantages such as long cycle life, good safety performance, and rapid charging and discharging.

[0003] Currently, in the lithium battery industry, anode sheets, cathode sheets, and separators are typically wound together to form wound cells. These cells have corners and non-corner areas. During the electrolysis process, excessive compressive stress on the anode and cathode sheets can cause the electrolyte to be over-extruded in these corners, leading to changes in the electrolyte's physical form, such as precipitation and leakage. This results in lower lithium ion conductivity in these corners than in non-corner areas, making lithium deposition more likely at these corners. This can lead to defects such as excessive cell thickness and cycling failure. Utility Model Content

[0004] The main purpose of the utility model is to provide a battery cell and a lithium-ion battery, aiming to solve the problem that the corner areas of the existing battery cells are easily over-extruded and thus lithium deposition occurs.

[0005] To achieve the above objectives, the present invention provides, on one hand, a battery cell, comprising 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 stacked and wound in sequence to form the battery cell, and each winding of the anode sheet, the cathode sheet, and the separator has a straight portion and a curved portion;

[0006] In which, the cathode sheet includes a thinned section and a constant thickness section, the thinned section and the constant thickness section are alternately connected along the winding direction of the cathode sheet, the thickness of the thinned section is less than the thickness of the constant thickness section, the thinned section in each winding circle is located in the curved portion of the corresponding winding circle, and the constant thickness section in each winding circle is located in the straight portion of the corresponding winding circle.

[0007] In some embodiments, the length of the thinned section is less than or equal to the arc length of the corresponding curved portion.

[0008] In some embodiments, the lengths of the thinned sections in different winding turns increase as the number of winding turns increases.

[0009] In some embodiments, the width of the thinned section is less than or equal to the width of the cathode sheet; and / or,

[0010] The width of the equal thickness section is less than or equal to the width of the cathode sheet.

[0011] In some embodiments, the ratio of the thickness of the thinned section to the thickness of the constant thickness section is greater than or equal to 80% and less than or equal to 95%.

[0012] In some embodiments, two curved portions are formed in each of the winding coils, and at least one of the two curved portions is provided with the thinned section.

[0013] In some embodiments, one thinned section is provided in each of the curved portions, and the two thinned sections have the same length and / or width and / or thickness.

[0014] In some embodiments, the cathode sheet includes an active coating and a current collector, wherein the active coating is coated on at least one surface of the current collector;

[0015] Wherein, the active coating includes the thinned sections and the equal-thickness sections that are alternately connected.

[0016] In some embodiments, the active coating is coated on two opposite surfaces of the current collector.

[0017] On the other hand, the present invention provides a lithium-ion battery, comprising a housing, an electrolyte, and the battery core described above, wherein the battery core is disposed in the housing, and the electrolyte is filled in the housing.

[0018] The battery cell provided in the present application is configured such that the cathode sheet is divided into a thinned section and an equal-thickness section, with a thickness difference between the thinned section and the equal-thickness section, and the thinned section in each winding coil is located within the curved portion of the corresponding winding coil, and the equal-thickness section is located within the straight portion of the corresponding winding coil. In this way, when the cathode sheet and the anode sheet are wound, there is a gap between the cathode sheet and the anode sheet, thereby avoiding excessive squeezing of the cathode sheet and the anode sheet, which is beneficial to the storage of the electrolyte and reduces the probability of lithium deposition in the curved portion of the battery cell during subsequent charge and discharge cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural diagram of an embodiment of a battery cell of the present utility model;

[0020] Figure 2 This is a partial structural diagram of an embodiment of a battery cell of the present utility model;

[0021] Figure 3 This is a partial structural diagram of an embodiment of a battery cell of the present invention.

[0022] Description of Figure Numbers:

[0023] Label name Label name 1 cathode sheet 2 diaphragm 3 Anode 11 current collector 12 Active coating 101 Straight part 102 Bend 121 Thinning section 122 Equal thickness segment 4 Winding ring 100 battery cells DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the schemes in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0026] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element.

[0027] In addition, the descriptions of "first," "second," etc. in this utility model are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this utility model.

[0028] During the charging process of lithium-ion batteries, lithium ions will be deintercalated from the cathode and embedded in the anode; however, when some abnormal situations occur, such as insufficient space for lithium embedding in the anode, too much resistance for lithium ions to embed in the negative electrode, or lithium ions are deintercalated from the cathode too quickly but cannot be embedded in the anode in equal amounts, the lithium ions that cannot be embedded in the anode can only gain electrons on the surface of the anode, thereby forming silvery-white metallic lithium. This is commonly known as lithium plating.

[0029] Currently, in the lithium battery industry, anode sheets, cathode sheets, and separators are generally wound together to form wound cells. These cells have corner and non-corner areas. During the charge-discharge cycle, if excessive compressive stress is applied to the anode and cathode sheets, the electrolyte may be over-extruded in the corners, causing changes in the electrolyte's physical form, such as precipitation and leakage. This results in the electrolyte capacity in the corners being lower than in the non-corner areas. The separator and anode sheet are prone to poor contact at the corners, preventing lithium ions from reaching the anode sheet, resulting in lithium deposition. This can lead to defects such as excessive cell thickness and cycle throttling, and may even cause combustion or explosion.

[0030] To solve the above problems, please refer to Figure 1 The present invention provides a battery cell 100, comprising an anode sheet 3, a cathode sheet 1, and a separator 2 disposed between the anode sheet 3 and the cathode sheet 1. The anode sheet 3, the separator 2, and the cathode sheet 1 are stacked and wound in sequence to form the battery cell 100, and each winding coil 4 of the anode sheet 3, the cathode sheet 1, and the separator 2 forms a straight portion 101 and a curved portion 102. The cathode sheet 1 includes a thinned section 121 and a uniform thickness section 122, which are alternately connected along the winding direction of the cathode sheet 1. The thickness of the thinned section 121 is less than that of the uniform thickness section 122. The thinned section 121 in each winding coil 4 is located within the curved portion 102 of the corresponding winding coil 4, and the uniform thickness section 122 in each winding coil 4 is located within the straight portion 101 of the corresponding winding coil 4.

[0031] In this embodiment, a thinning section 121 is provided at the bend 102, that is, the portion of the cathode sheet 1 corresponding to the bend 102 is thinned to form the thinned section 121, and there is a thickness difference between the thinned section 121 and the equal-thickness section 122. In this way, after the thinned cathode sheet 1 and the anode sheet 3 are wound, the gap between the portion of the cathode sheet 1 located in the bend 102 and the anode sheet 3 is increased, which is beneficial to the storage of the electrolyte during the subsequent packaging of the battery cell 200, and reduces the probability of lithium deposition in the bend 102 during the subsequent charge and discharge cycles of the battery cell 100.

[0032] The uniform thickness section 122 is located in the straight portion 101 and primarily carries lithium ion transport. Maintaining a certain thickness facilitates uniform current distribution and efficient lithium ion transport. This design increases the proportion of active material in the battery cell 100 without sacrificing significant structural integrity or current transmission capacity, thereby improving the energy density of the battery cell 100.

[0033] The beneficial effects of providing the thinned section 121 on the curved portion 102 and the uniform thickness section 122 on the straight portion 101 are as follows:

[0034] Before winding the battery cell 100, the curved portion 102 of the cathode sheet 1 is thinned to form a thinned section 121. This increases the gap between the cathode sheet 1 and the anode sheet 3 during winding, facilitating electrolyte storage and alleviating compressive stress to a certain extent, thereby preventing the risk of lithium deposition or performance degradation caused by excessive stress. Furthermore, the uniform thickness section 122 provides stable support for the straight portion 101, contributing to the overall structural stability of the battery cell 100.

[0035] In some embodiments, the anode sheet 3, the separator 2 and the cathode sheet 1 are stacked in sequence to form a multilayer structure. This stacking method ensures good contact between each layer, which is beneficial to the transmission of lithium ions. The battery cell 100 with a laminated structure is wound up to form the main body of the wound battery cell. In the winding structure of the battery cell 100, a new winding coil 4 is formed for each winding. Among these winding coils 4, the part directly facing the central axis of the battery cell 100 is a straight portion 101, which is relatively flat and is beneficial to the linear transmission of lithium ions. As the winding proceeds, curved portions 102 are gradually formed on both sides of the battery cell 100.

[0036] In the prior art, in addition to the excessive squeezing of the gap between the cathode sheet 1 and the anode sheet 3 in the curved portion 102 which may cause lithium deposition in the battery cell 100, the mismatch in the ratio of the capacity of the anode sheet 3 to the capacity of the cathode sheet 1 (CB value) may also cause lithium deposition in the battery cell 100.

[0037] In the curved portion 102 of the wound battery cell, the anode sheet 3 in the inner circle is slightly smaller than the cathode sheet 1 in the outer circle, that is, the active material of the anode sheet 3 in the inner circle is less than the active material of the cathode sheet 1 in the outer circle. This phenomenon leads to a mismatch in the CB values of the cathode sheet 1 and the anode sheet 3 in the curved portion 102, which makes lithium deposition prone, so it is necessary to compensate for the curvature loss.

[0038] To solve the above problems, please refer to Figure 2 The cathode sheet 1 includes an active coating 12 and a current collector 11. The active coating 12 is applied to at least one surface of the current collector 11 and includes alternating thinned sections 121 and uniformly thickened sections 122. Specifically, the portion of the active coating 12 located within the curved portion 102 is thinned to form the thinned sections 121. This reduces the amount of active material in the cathode sheet 1 within the curved portion 102, thereby matching the CB value and reducing the probability of lithium deposition in the battery cell 100.

[0039] In this embodiment, active coating 12 is a layer or layers of material coated on the surface of current collector 11, containing active substances capable of participating in electrochemical reactions. Active coating 12 can be applied solely to one surface of current collector 11 or symmetrically to both surfaces of current collector 11. The specific application depends on actual needs and is not limited herein.

[0040] As a preferred embodiment of the present application, the active coating 12 is applied to two opposite surfaces of the current collector 11. Figure 2 Coating the active coating 12 on both sides of the current collector 11 can increase the active material inside the battery cell 100 and improve the energy density.

[0041] Please continue to refer to Figure 2 In order to reduce the extrusion stress of the curved portion 102 of the cathode sheet 1, the active coating 12 of the cathode sheet 1 is locally thinned by laser cleaning before winding, thereby reducing the thickness of the active coating 12 of the cathode sheet 1 located in the curved portion 102, reducing the mechanical stress caused by bending, and helping to prevent cracks and breakage. At the same time, the active material content of the cathode sheet 1 in the curved portion 102 is reduced, matching the CB value of the anode sheet 3 and the cathode sheet 1 in the curved portion 102, and further reducing the probability of lithium deposition in the curved portion 102 of the battery cell 100 during the charge and discharge cycle.

[0042] Corresponding to the straight portion 101 of the cathode sheet 1, the active coating 12 is not thinned to maintain a uniform thickness, forming a uniform thickness section 122. The uniform thickness section 122 ensures that sufficient active material participates in the electrochemical reaction, thereby maintaining the capacity and energy density of the battery.

[0043] In some embodiments, the length of the thinned section 121 is less than or equal to the arc length of the corresponding curved portion 102 .

[0044] Please refer to Figure 3 The length of the thinned section 121 of the present invention is equal to the arc length of the corresponding bent portion 102, and the thinned portion of the active coating 12 will not exceed the actual shape of the bent portion 102, avoiding unnecessary material waste. At the same time, this design also avoids the thinned section 121 being too short, which would cause the local bent portion 102 of the cathode sheet 1 to produce excessive stress concentration due to the active coating 12 being too thick, thereby improving the flexibility and durability of the cathode sheet 1.

[0045] In some embodiments, the lengths of the thinned sections 121 in different windings 4 increase as the number of windings 4 increases.

[0046] Please refer to Figure 1In a wound battery, as the battery is wound layer by layer from the inside to the outside, the bending radius of each layer of the winding coil 4 will gradually increase. In order to keep the thinned section 121 filling the entire curved portion 102 as much as possible to reduce the probability of lithium plating during the charge and discharge cycle of the battery cell 100, the length of the thinned section 121 also needs to be adjusted accordingly. Therefore, in this embodiment, as the number of layers of the winding coil 4 increases, the length of the thinned section 121 also increases accordingly, which helps to increase the gap between the outer cathode sheet 1 and the anode sheet 3, relieve the extrusion stress, and match the CB value of the anode sheet 3 and the cathode sheet 1. In addition, the volume change that may occur in the battery during the charge and discharge process is also taken into account. As lithium ions are inserted and deintercalated, the volume of the cathode sheet 1 will change. The increase in the length of the thinned section 121 provides a certain buffer space for this volume change, which helps to reduce the mechanical stress and damage to the cathode sheet 1 caused by the volume change.

[0047] In some embodiments, the width of the thinned section 121 is less than or equal to the width of the cathode sheet 1 .

[0048] It can be understood that the width of the thinned section 121 of the present invention can be less than the width of the cathode sheet 1, or can be equal to the width of the cathode sheet 1. In one possible embodiment, the width of the thinned section 121 is equal to the width of the cathode sheet 1, which can relieve the extrusion stress on the cathode 1 and the anode sheet 3 when the battery cell 100 is wound, while retaining more active material, ensuring the overall energy density and performance of the battery cell 100. Moreover, in the curved portion 102 of the cathode sheet 1, the active coating 12 is thinned throughout the entire width, ensuring that the cathode sheet 1 maintains good flexibility throughout the entire width when bent, avoiding cracks or fractures caused by local stress concentration. At the same time, since the thinned width of the thinned section 121 is consistent with the width of the cathode sheet 1, the production process is simplified, and no additional width adjustment of the active coating 12 is required.

[0049] In some embodiments, the width of the uniform thickness section 122 is less than or equal to the width of the cathode sheet 1 .

[0050] It can be understood that the width of the equal-thickness section 122 of the present invention can be smaller than the width of the cathode sheet 1 , or can be equal to the width of the cathode sheet 1 .

[0051] In this embodiment, in the straight portion 101 of the cathode sheet 1, the width of the uniform thickness section 122 is equal to the width of the cathode sheet 1. Similarly, the uniform thickness section 122 having the same width as the cathode sheet 1 simplifies the production process and improves production efficiency.

[0052] In some embodiments, the ratio of the thickness of the skived section 121 to the thickness of the uniform thickness section 122 is greater than or equal to 80% and less than or equal to 95%. In this embodiment, by setting the ratio of the thickness of the skived section 121 to the thickness of the uniform thickness section 122 to be greater than or equal to 80%, the skived section 121 is prevented from being too thin, thereby retaining a certain amount of active material without excessively sacrificing the battery's capacity and energy density. Furthermore, the skived section 121 is prevented from being too thick, which would result in a large thickness difference between the skived section 121 and the uniform thickness section 122 and would thus generate a large compressive stress between the anode sheet and the skived section 121.

[0053] For example, the thickness of the uniform thickness section 122 of the battery cell 100 provided by the present invention is 100 μm. Before winding, the active coating 12 of the cathode sheet 1 is laser thinned to form a thinned section 121. The thickness of the thinned section 121 is between 80 μm and 90 μm, meaning that the active coating 12 is thinned by 10 μm to 20 μm. For example, the active coating 12 can be thinned by 10 μm, 15 μm, or 20 μm, depending on actual needs and not limited by the present invention.

[0054] As a preferred embodiment of the present invention, the thickness of the thinned section 121 is 90 μm. It can be understood that laser thinning the active coating 12 by 10 μm can, to a certain extent, increase the gap between the cathode sheet 1 and the anode sheet 3 at the curved portion 102, which is beneficial for electrolyte storage, thereby reducing the probability of lithium deposition in the battery cell 100. Furthermore, while matching the CB value, the active coating 12 of the cathode sheet 1 in the curved portion 102 is not excessively thinned, resulting in a significant reduction in the active material content of the cathode sheet 1 and affecting the energy density of the battery cell 100.

[0055] In some embodiments, in the same curved portion 102 , the lengths, widths, and thicknesses of the two thinned sections 121 of the active coating 12 are equal.

[0056] It can be understood that in the same curved portion 102 of the current collector 11, whether it is the active coating 12 on the upper surface or the active coating 12 on the lower surface, the length, width and thickness of their thinned sections 121 are equal. The length of the thinned section 121 along the bending direction of the current collector 11 is equal in the two active coatings 12. This ensures that the flexibility of the two coatings at the same position is consistent during the bending process. The size of the thinned section 121 in the direction perpendicular to the surface of the current collector 11 (i.e., the width direction) is also equal in the two active coatings 12, which ensures the uniformity of the thinned section 121 in the width direction and avoids stress concentration caused by inconsistent width. The thickness of the thinned section 121 is also equal in the two active coatings 12, which means that the amount of material reduced by the thinning part is the same in the two coatings, thereby maintaining the symmetry of the thinned section 121 in the thickness direction.

[0057] In some embodiments, two bent portions 102 are formed in each winding coil 4 , and at least one of the two bent portions 102 is provided with a thinned section 121 .

[0058] When the cathode sheet 1 is wound into a circular shape or a multi-layer flat shape, a plurality of winding coils 4 are formed. Figure 1 In each winding coil 4, two opposing curved portions 102 are formed due to the curvature of the current collector 11. At least one of the two curved portions 102 is provided with a thinned section 121. These thinned sections 121 are used to increase the gap between the cathode sheet 1 and the anode sheet 2 in the curved portion 102 to better store the electrolyte, and to reduce the active material of the cathode sheet 1 in the curved portion 102 to match the CB value of the anode sheet 3 and the cathode sheet 1, thereby improving the performance of the battery cell 100 while reducing the probability of lithium plating.

[0059] In some embodiments, in order to further optimize the extrusion stress of the curved portion 102 , a thinned section 121 is provided in each curved portion 102 , and the two thinned sections 121 have the same length and / or width and / or thickness.

[0060] In the same winding coil 4, the lengths, widths, and thicknesses of the two thinned sections 121 within the curved portion 102 on opposite sides may be different or the same. To maintain the consistency of the battery cell 100 and simplify the production process, they are equal in length, width, and thickness, ensuring uniformity and stability of the cathode sheet 1 during the winding process.

[0061] If the active coating 12 is applied to two opposite surfaces of the current collector 11 as described above, there are two curved portions 102 within the same winding coil 4, namely, the outer and inner curved portions, and at least one of the two curved portions 102 is provided with a thinned section 121. In one possible embodiment, the thinned section 121 is provided only on the inner curved portion 102 of the winding coil 4. When the battery cell 100 is wound, the gap between the cathode sheet 1 and the anode sheet 3 at the curved portion 102 is increased to a certain extent, and more active material is retained, thereby improving the energy density of the battery cell 100.

[0062] In another possible implementation, please refer to Figure 3 Both the inner and outer curved portions 102 of the winding coil 4 are provided with a skived section 121. These skived sections 121 increase the gap between the cathode sheet 1 and the anode sheet 3, further alleviating the compressive stress generated during bending and optimizing the overall battery performance. They are equal in length, width, and thickness. This consistent design simplifies the production process and ensures uniformity and stability of the cathode sheet 1 during the winding process.

[0063] The present invention also provides a lithium-ion battery comprising a housing and the aforementioned battery cell 100. The battery cell 100 is disposed within the housing and filled with electrolyte. A thinned section 121 is provided on the curved portion 102 of the cathode sheet 1 of the battery cell 100. This prevents excessive compression of the cathode sheet 1 and the anode sheet 3 during winding of the battery cell 100, leaving a gap to store more electrolyte, thereby reducing the probability of lithium deposition during the charge and discharge cycles of the battery cell 100.

[0064] Since the lithium-ion battery adopts all the technical solutions of all the embodiments of the battery cell 100, the lithium-ion battery of the present invention also has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described one by one here.

[0065] The above description is only part or preferred embodiments of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. All equivalent structural transformations made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.

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 stacked and wound in sequence to form the battery cell, and each winding of the anode sheet, the cathode sheet, and the separator has a straight portion and a curved portion; In which, the cathode sheet includes a thinned section and a constant thickness section, the thinned section and the constant thickness section are alternately connected along the winding direction of the cathode sheet, the thickness of the thinned section is less than the thickness of the constant thickness section, the thinned section in each winding circle is located in the curved portion of the corresponding winding circle, and the constant thickness section in each winding circle is located in the straight portion of the corresponding winding circle.

2. The battery cell according to claim 1, characterized in that The length of the thinned section is less than or equal to the arc length of the corresponding curved portion.

3. The battery cell according to claim 2, characterized in that The lengths of the thinned sections in different winding turns increase as the number of winding turns increases.

4. The battery cell according to claim 1, characterized in that The width of the thinned section is less than or equal to the width of the cathode sheet; and / or, The width of the equal thickness section is less than or equal to the width of the cathode sheet.

5. The battery cell according to claim 1, characterized in that The ratio of the thickness of the thinned section to the thickness of the equal-thickness section is greater than or equal to 80% and less than or equal to 95%.

6. The battery cell according to claim 1, characterized in that Two bent portions are formed in each winding coil, and at least one of the two bent portions is provided with the thinned section.

7. The battery cell according to claim 6, characterized in that A thinned section is provided in each of the curved portions, and the two thinned sections have the same length and / or width and / or thickness.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The cathode sheet includes an active coating and a current collector, wherein the active coating is coated on at least one surface of the current collector; Wherein, the active coating includes the thinned sections and the equal-thickness sections that are alternately connected.

9. The battery cell according to claim 8, characterized in that The active coating is coated on two opposite surfaces of the current collector.

10. A lithium ion battery, characterized in that: The invention comprises a shell, an electrolyte and the battery core according to any one of claims 1 to 9, wherein the battery core is arranged in the shell and the electrolyte is filled in the shell.

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