Battery roll core structure and secondary battery

Abstract

The utility model discloses a battery roll core structure and a secondary battery, the battery roll core comprises a first pole piece and a second pole piece, the polarity of the second pole piece is opposite to that of the first pole piece, and the first pole piece comprises a first winding starting section; the second pole piece comprises a second winding starting section; the first winding starting section is arranged in the first direction, the second winding starting section is arranged in the second direction, and the first direction is opposite to the second direction. Compared with the prior art, the battery roll core structure provided by the utility model has the advantages that by changing the winding mode of the innermost ring of the battery roll core, the problem that the pole piece of the innermost ring of the battery roll core is easy to curl is effectively solved, the processing difficulty of the battery roll core is reduced, the thickness of the battery core is reduced, and the volume energy density of a secondary battery is improved.

Description

Technical Field

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

[0002] Secondary batteries generally consist of battery cells, electrolyte, and battery casing. Battery cells can be divided into laminated cells and wound cells. In the field of power lithium batteries, wound cells have certain advantages. Wound cells, as a common cell structure, have advantages such as high production efficiency and stable quality, and are widely used in small, conventional square and cylindrical batteries. However, in the manufacturing process of wound cells, the positive and negative electrodes are wound in the same direction, while the innermost negative electrode often uses a single-sided coating structure. Although this structure simplifies the process to some extent, it also brings a series of technical problems and challenges:

[0003] 1) When the innermost negative electrode of a lithium battery winding cell adopts a single-sided coating structure, due to the non-uniformity of the coating and the special characteristics of the single-sided coating structure, it is easy to cause capacity loss, performance degradation and lithium plating in the battery section.

[0004] 2) Due to the special nature of the single-sided coating structure, the stress on both sides of the current collector is inconsistent, making it easy to curl. During the bonding process of the electrode and the separator, problems such as misalignment and wrinkles are likely to occur, which increases the difficulty of processing and manufacturing, thereby affecting the internal structure and stability of the battery cell.

[0005] 3) Although the single-sided coating structure of the negative electrode simplifies the process to some extent, the performance problems and safety hazards it brings often require additional process steps and quality control measures to compensate for them. This not only increases the complexity of the process but also raises production costs.

[0006] Therefore, in the face of these problems exposed in the practical application of battery windings, researchers urgently need to provide a new technical solution to address these issues. Utility Model Content

[0007] The purpose of this application is to provide a battery core structure that improves the winding method of the innermost ring of the battery core in the prior art, effectively improves the problem of easy bending of the innermost ring electrode of the battery core, and improves the volumetric energy density of the battery core.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A battery core structure, comprising:

[0010] A first electrode and a second electrode with opposite polarity to the first electrode, wherein the first electrode includes a first winding start section; and the second electrode includes a second winding start section.

[0011] The first winding starting segment is arranged along a first direction, and the second winding starting segment is arranged along a second direction, wherein the first direction is opposite to the second direction.

[0012] Preferably, both the first electrode and the second electrode have a double-sided coating structure.

[0013] Preferably, the first electrode further includes a first bending section, the first bending section being connected to the first winding start section along the winding direction, and the second winding start section being disposed inside the first bending section.

[0014] Preferably, the second electrode further includes a second bending section, which is connected to the second winding start section along the winding direction, and the first winding start section is disposed inside the second bending section.

[0015] Preferably, the first bending segment is provided with double-sided protective adhesive, the double-sided protective adhesive is provided with side A and side B opposite to it, and side A is connected to the first bending segment.

[0016] Preferably, the battery core structure further includes a first separator and a second separator, the first separator and the second separator being disposed on two opposite surfaces of the second electrode.

[0017] Preferably, one end of side B is connected to the first diaphragm, and the other end is connected to the second diaphragm;

[0018] Alternatively, the B side is connected to the second diaphragm.

[0019] Preferably, the surface of the first bent section opposite to the double-sided protective adhesive is provided with a groove, and the double-sided protective adhesive is embedded in the groove.

[0020] Preferably, the heat resistance temperature range of the double-sided protective adhesive is ≥150℃.

[0021] This utility model also provides a secondary battery, including the battery core structure described above.

[0022] The beneficial effects of this utility model are as follows: The battery core structure provided in this application effectively improves the problem of easy bending of the innermost electrode sheet of the battery core by changing the winding method of the innermost circle of the battery core, reduces the processing difficulty of the battery core, and at the same time reduces the thickness of the cell and increases the volumetric energy density of the secondary battery. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the battery core structure in one embodiment of this application.

[0024] Wherein: 1. First electrode; 11. First winding start section; 12. First bending section; 2. Second electrode; 21. Second winding start section; 22. Second bending section; 3. First diaphragm; 4. Second diaphragm; 5. Double-sided protective adhesive. Detailed Implementation

[0025] To make the technical solution and advantages of this utility model clearer, the technical solution of this application will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail with reference to specific embodiments, but this is not intended to limit the present invention.

[0029] According to a first aspect of the present invention, a battery core structure is provided, comprising:

[0030] A first electrode 1 and a second electrode 2 with opposite polarity to the first electrode 1, the first electrode 1 including a first winding start section 11; the second electrode 2 including a second winding start section 21;

[0031] The first winding starting segment 11 is arranged along a first direction, and the second winding starting segment 21 is arranged along a second direction, with the first direction being opposite to the second direction. This application effectively improves the problem of easy bending of the innermost electrode sheet of the battery core by changing the winding method of the innermost ring of the battery core, reduces the processing difficulty of the battery core, and at the same time reduces the cell thickness and improves the volumetric energy density of the secondary battery.

[0032] In one embodiment of this application, both the first electrode 1 and the second electrode 2 are double-sided coated structures.

[0033] Both the first electrode 1 and the second electrode 2 have a double-sided coating structure, which has the following advantages:

[0034] 1) Double-sided coating fully utilizes both sides of the electrode, increasing the coating area of ​​active material and thus improving battery capacity and energy density. Compared to the existing technology where the innermost electrode of the battery core has a single-sided coating, double-sided coating can more effectively utilize the electrode material, improving the overall performance of the battery. Double-sided coating also makes electron transfer between the positive and negative electrodes more uniform and efficient during charging and discharging, helping to reduce internal resistance, improve charging and discharging efficiency, and thus extend battery life.

[0035] 2) In terms of battery electrode preparation, compared with electrodes with alternating single-sided and double-sided coatings, double-sided coated electrodes do not require multiple coating and drying operations, thus saving time and cost, helping to reduce errors and defect rates in the preparation process, and improving battery quality and stability.

[0036] 3) During the cell winding process, the double-sided coated electrode structure can reduce the misalignment and wrinkling of the battery electrode during the winding or stacking process, thereby reducing the risk of internal short circuit and helping to improve the safety and reliability of the battery.

[0037] In one embodiment of this application, the first electrode 1 further includes a first bending segment 12, which is connected to the first winding start segment 11 along the winding direction. A second winding start segment 21 is disposed inside the first bending segment 12. The second winding start segment 21 is close to the inside of the first bending segment 12, which can provide a corresponding active material layer for the active material layer of the first winding start segment 11 to carry out subsequent electrode reactions and improve the energy density of the battery.

[0038] In one embodiment of this application, the second electrode 2 further includes a second bending segment 22, which is connected to the second winding start segment 21 along the winding direction. A first winding start segment 11 is disposed inside the second bending segment 22. The first winding start segment 11 being disposed inside the second bending segment 22 provides a corresponding active material layer for the active material layer of the second winding start segment 21 to perform subsequent electrode reactions, thereby improving the energy density of the battery.

[0039] In one embodiment of this application, a double-sided protective adhesive 5 is provided on the first bending segment 12. The double-sided protective adhesive 5 is provided with side A and side B opposite to it, and side A is connected to the first bending segment 12.

[0040] In one embodiment of this application, the battery core structure further includes a first separator 3 and a second separator 4, the first separator 3 and the second separator 4 being disposed on two opposite surfaces of the second electrode 2, respectively.

[0041] In one embodiment according to this application, one end of side B is connected to the first diaphragm 3, and the other end is connected to the second diaphragm 4;

[0042] Alternatively, the B-side can be connected to the second diaphragm 4. When the first diaphragm 3 and the second diaphragm 4 are respectively connected to both ends of the B-side of the double-sided protective adhesive 5, the starting ends of the first diaphragm 3 and the second diaphragm 4 are flush with the starting position of the second electrode 2. Double-sided adhesive is applied to the diaphragm at the starting position of the second electrode 2 to fix the two layers of diaphragms to cover the second electrode, which can effectively prevent the diaphragms from wrinkling and shrinking. When only the second diaphragm 4 is connected to the B-side of the double-sided protective adhesive 5, the starting ends of the first diaphragm 3 and the second diaphragm 4 are not flush with the starting position of the second electrode 2. The parts of the first diaphragm 3 and the second diaphragm 4 that are longer than the second electrode 2 are wound in the innermost circle. This method is more commonly used because when the first diaphragm 3 and the second diaphragm 4 are longer, on the one hand, it is easier to process and manufacture, and existing equipment can be adapted with minimal modifications; on the other hand, it can increase the safety performance of the battery cell. Since the inner circle diaphragm is long enough, the positive and negative electrodes will not directly connect and short-circuit due to the diaphragm shrinking during the cyclic expansion of the battery cell.

[0043] In one embodiment of this application, a groove is provided on the surface of the first bent section 12 opposite to the double-sided protective adhesive 5, and the double-sided protective adhesive 5 is embedded in the groove. The double-sided protective adhesive 5 is embedded in the groove, which fixes the separator while achieving the effect of not increasing the thickness of the battery cell.

[0044] In one embodiment of this application, the heat resistance temperature range of the double-sided protective adhesive 5 is ≥150°C.

[0045] According to a second aspect of this application, a secondary battery is also provided, including the battery core structure described above.

[0046] According to a third aspect of this application, an electrical device is also provided, including the aforementioned secondary battery.

[0047] The electrical device can be a vehicle, mobile phone, portable device, laptop, ship, spacecraft, electric toy, or power tool. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles. Spacecraft include airplanes, rockets, space shuttles, and spacecraft. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. This application does not impose any special limitations on the above-mentioned electrical devices.

[0048] The present application will be further described below through specific embodiments. The following specific embodiments are only used to more clearly illustrate the technical solution of the present application, and should not be used to limit the scope of protection of the present application.

[0049] Example 1

[0050] The positive electrode sheet with a double-sided coating, the negative electrode sheet with a double-sided coating, the first separator, and the second separator are stacked in sequence and wound to obtain an electrode assembly. The electrode assembly is then placed in a packaging shell, electrolyte is injected into the packaging shell, and the shell is sealed to obtain a lithium-ion battery. The starting section of the winding of the positive electrode sheet is arranged along a first direction, and the starting section of the winding of the negative electrode sheet is arranged along a second direction, with the first and second directions being opposite.

[0051] Comparative Example 1

[0052] The positive electrode, separator, and negative electrode are stacked in sequence and wound to obtain an electrode assembly. The electrode assembly is then placed in a packaging shell, electrolyte is injected into the shell, and the assembly is sealed to obtain a lithium-ion battery. The positive and negative electrode sheets are wound in the same direction at the beginning, and the innermost negative electrode of the battery core has a single-sided coating structure.

[0053] Performance testing:

[0054] The lithium-ion batteries of Example 1 and Comparative Example 1 were tested for volumetric energy density, and the test results are shown in Table 1.

[0055] Table 1

[0056]

[0057] As can be seen from the test results in Table 1, the volumetric energy density of the lithium-ion battery in Example 1 is higher than that in Comparative Example 1. This indicates that the present invention improves the winding method of the innermost ring of the battery core in the prior art, effectively improves the problem of easy bending of the innermost ring electrode of the battery core, and improves the volumetric energy density of the battery core.

[0058] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, this utility model is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on this utility model are within the protection scope of this utility model. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on this utility model.

Claims

1. A battery core structure, characterized in that, include: A first electrode and a second electrode with opposite polarity to the first electrode, wherein the first electrode includes a first winding start section; The second electrode includes a second winding starting section; The first winding starting segment is arranged along a first direction, and the second winding starting segment is arranged along a second direction, wherein the first direction is opposite to the second direction.

2. The battery core structure according to claim 1, characterized in that, Both the first electrode and the second electrode have a double-sided coating structure.

3. The battery core structure according to claim 1, characterized in that, The first electrode further includes a first bending section, which is connected to the first winding start section along the winding direction, and the second winding start section is disposed inside the first bending section.

4. The battery core structure according to claim 1, characterized in that, The second electrode also includes a second bending section, which is connected to the second winding start section along the winding direction, and the first winding start section is disposed inside the second bending section.

5. The battery core structure according to claim 3, characterized in that, The first bending section is provided with double-sided protective adhesive, which has an A side and a B side opposite to it, and the A side is connected to the first bending section.

6. The battery core structure according to claim 5, characterized in that, The battery core structure also includes a first separator and a second separator, which are respectively disposed on two opposite surfaces of the second electrode.

7. The battery core structure according to claim 6, characterized in that, One end of side B is connected to the first diaphragm, and the other end is connected to the second diaphragm; Alternatively, the B side is connected to the second diaphragm.

8. The battery core structure according to claim 5, characterized in that, The first bent section has a groove on the surface opposite to the double-sided protective adhesive, and the double-sided protective adhesive is embedded in the groove.

9. The battery core structure according to claim 5, characterized in that, The heat resistance temperature range of the double-sided protective adhesive is ≥150℃.

10. A secondary battery, characterized in that: Includes the battery core structure as described in any one of claims 1 to 9.

Images