Anode strip, battery cell, battery and battery module
By designing alternating thicker bending sections and straight sections on the lithium-ion battery anode sheet, the problem of low battery cycle performance caused by anode sheet expansion was solved, thus improving battery performance.
Patent Information
- Application Number
- CN202422322914.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2025-11-11
- Estimated Expiration
- 2034-09-23
AI Technical Summary
During the charging and discharging process of lithium-ion batteries, the expansion of the anode plate causes stress concentration in the corner area of the cell, which squeezes out the electrolyte, resulting in lithium plating and reducing the battery's cycle performance.
An anode sheet is designed, comprising a bending section and a straight section with a thickness greater than that of a straight section, which are alternately arranged along its length. The bending section is pre-expanded and applied to the corner area of the battery cell to alleviate stress concentration caused by the expansion of the anode sheet.
This reduces the expansion of the anode plate during battery charging and discharging, improves lithium plating at cell corners, and enhances battery cycle performance.
Smart Images
Figure CN223539605U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of lithium battery technology, and in particular to an anode sheet, a cell, a battery, and a battery module. Background Technology
[0002] A lithium-ion battery includes a cell structure, which is formed by winding a positive electrode, a separator, and a negative electrode. The middle region of the cell is a flat region, and the two end regions are corner regions. During the charging and discharging process of a lithium-ion battery, lithium ions migrate from the cathode plate in the cell to the anode plate and embed into the crystal lattice of the anode plate, causing the anode plate to gradually expand.
[0003] However, due to the mutual binding between the electrodes in the corner area of the cell, the expanding anode sheet will continuously squeeze the adjacent separator and cathode sheet, causing stress concentration in the local area of the cell corner area and squeezing out the electrolyte in that area, resulting in the gradual loss of electrolyte in that area, which in turn causes the anode sheet surface to deteriorate and lithium plating to occur, resulting in low cycle performance of the battery. Utility Model Content
[0004] The main purpose of this invention is to propose an anode sheet that aims to solve the problem of low battery cycle performance caused by the deterioration of the anode sheet surface and the occurrence of lithium plating due to anode sheet expansion.
[0005] To achieve the above objectives, this utility model proposes an anode sheet, which includes an electrode body;
[0006] The electrode body has a bending section and a straight section arranged alternately along its length direction. Each bending section is expanded, and the thickness of the bending section is greater than the thickness of the straight section.
[0007] In some embodiments, the thickness expansion rate of the section to be bent is greater than 10%.
[0008] In some embodiments, the section to be bent contains an expansion fluid that causes it to expand.
[0009] In some embodiments, the swelling fluid is deionized water.
[0010] In some embodiments, the droplet size of the deionized water is less than 30 μm.
[0011] In some embodiments, the weight loss rate of the electrode body is less than 0.5%.
[0012] In some embodiments, the radius of the segment to be bent after bending is R, the deviation between the theoretical length of the segment to be bent and the actual length of the segment to be bent is Δ, and the actual length of the segment to be bent is L=π / 2*RΔ.
[0013] This utility model also proposes a battery cell, which includes an anode sheet, a diaphragm, and a cathode sheet that are stacked and wound together, wherein the diaphragm is disposed between the anode sheet and the cathode sheet;
[0014] Wherein, the anode sheet is the anode sheet described above, the battery cell is wound to form a straight area and a corner area, the straight section is located in the straight area, and the section to be bent is located in the corner area.
[0015] This utility model also proposes a battery, including a casing and the aforementioned battery cell, wherein the battery cell is disposed in the casing.
[0016] This utility model also proposes a battery module comprising multiple batteries as described above.
[0017] When the anode sheet provided by this utility model is applied in a battery cell, its straight section corresponds to the straight area of the battery cell, while the section to be bent is relatively bent and corresponds to the corner area of the battery cell. Since the section to be bent has been pre-expanded, its thickness is greater than that of the straight section. Therefore, the degree of expansion of the section to be bent during subsequent charge and discharge cycles will be reduced. This alleviates the phenomenon of local stress concentration in the corner area of the battery cell caused by excessive expansion of the anode sheet, which squeezes out the electrolyte. This improves the lithium plating phenomenon in the corner area and thus improves the cycle performance of the battery. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the structure of the electrode body in one embodiment of the present invention;
[0019] Figure 2 This is a schematic diagram of the battery cell structure in one embodiment of the present invention;
[0020] Explanation of icon numbers:
[0021] label name label name 100 anode plate 110 pole piece body 111 Section to be bent 112 Straight section 120 Expanding fluid 1000 battery cells 200 diaphragm 300 cathode plate P Straight area G Corner area
[0022] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0023] The solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.
[0024] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.
[0025] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.
[0026] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.
[0027] This utility model embodiment provides an anode sheet 100, referring to... Figure 1 The anode sheet 100 includes an electrode body 110, which has a bending section 111 and a straight section 112 arranged alternately along its length. Each bending section 111 is expanded, and the thickness of the bending section 111 is greater than the thickness of the straight section 112. The bending section 111 and the straight section 112 are integrally formed to form the electrode body 110. Before applying the electrode body 110 to the battery cell 1000, the bending section 111 is expanded so that its thickness is greater than the thickness of the straight section 112. Then, the electrode body 110 is applied to the battery cell 1000. At this time, the electrode body 110 is wound, the straight section 112 is arranged in a straight line, and the bending section 111 is bent.
[0028] When the anode sheet 100 provided by this utility model is applied in the battery cell 1000, its straight section 112 corresponds to the straight region P of the battery cell 1000, while the section to be bent 111 is relatively bent and corresponds to the corner region G of the battery cell 1000. Since the section to be bent 111 has been pre-expanded, the thickness of the section to be bent 111 is greater than the thickness of the straight section 112. Therefore, the degree of expansion of the section to be bent 111 during subsequent charge and discharge cycles will be reduced, which alleviates the phenomenon that the battery cell 1000 is squeezed out of electrolyte due to local stress concentration in the corner region G caused by excessive expansion of the anode sheet 100. This improves the lithium plating phenomenon in the corner region G and thus improves the cycle performance of the battery.
[0029] In some embodiments, the thickness expansion rate of the bending segment 111 is greater than 10%. The thickness of the bending segment 111 after rolling is D1, and the thickness of the bending segment 111 after expansion is D2. The thickness expansion rate D of the bending segment 111 satisfies D = (D2 - D1) / D1. Given a fixed thickness of the bending segment 111 after rolling, a larger thickness expansion rate means a larger thickness D2 after expansion, resulting in less expansion of the anode plate 100 during subsequent battery charge-discharge cycles. When the thickness expansion rate of the bending segment 111 is greater than 10%, it can better alleviate the phenomenon of localized stress concentration at the corner of the cell 1000 caused by the expansion of the anode plate 100, which leads to electrolyte displacement, thereby improving lithium plating in the corner area.
[0030] In some embodiments, the section to be bent 111 contains an expansion liquid 120 that causes it to expand. The expansion liquid 120 is a liquid capable of expanding the section to be bent 111. Before the anode sheet 100 is wound, the expansion liquid 120 is sprayed onto at least one of the two opposing surfaces of the section to be bent 111, causing it to expand. Optionally, the expansion liquid 120 is sprayed onto only one of the two opposing surfaces of the section to be bent 111; or, the expansion liquid 120 is sprayed onto both opposing surfaces of the section to be bent 111. Optionally, the expansion liquid 120 is an electrolyte in a battery, which can cause a chemical reaction in the anode sheet 100, thereby causing the anode sheet 100 to expand; or, the expansion liquid 120 is an organic solvent, which can dissolve components in the anode sheet 100, thereby causing the anode sheet 100 to expand loosely. Examples of organic solvents include acetonitrile and dimethyl carbonate.
[0031] Reference Figure 1In some embodiments, the expansion fluid 120 is deionized water. Deionized water refers to a liquid from which almost all ions have been removed. Because deionized water contains virtually no impurities or ions, it can effectively penetrate from the surface of the section to be bent 111 to its interior, causing the section to absorb water and expand. Furthermore, deionized water is relatively pure, effectively preventing adverse chemical reactions with the anode plate 100 and ensuring the overall structural stability of the anode plate 100.
[0032] In some embodiments, the droplet size of deionized water is less than 30 μm. That is, the droplet size of deionized water can be set within the range of less than 30 μm, for example, the droplet size of deionized water is 0 μm, 15 μm, or 30 μm. The droplet size of deionized water affects the performance of the anode plate 100. If the droplet size of deionized water is too large, for example, greater than 30 μm, the deionized water will dissolve the adhesive on the surface of the anode plate 100, causing uneven spots on the surface of the anode plate 100. When this anode plate 100 is used in a battery, poor contact is likely to occur, resulting in low battery conductivity. Specifically, the droplet size of deionized water can be set with reference to the density of the anode plate 100. For example, when the density of the anode plate 100 is high, the droplet size of deionized water can be set to 0 μm; when the density of the anode plate 100 is medium, the droplet size of deionized water can be set to 15 μm; and when the density of the anode plate 100 is low, the droplet size of deionized water can be set to 30 μm. The above data is illustrative only and is not restrictive.
[0033] In some embodiments, the weight loss rate of the electrode body 110 is less than 0.5%. As described above regarding the anode sheet 100, the section to be bent 111 can absorb the expansion liquid 120 sprayed on the surface of the section to be bent 111, thereby causing expansion. After the section to be bent 111 of the anode sheet 100 expands by absorbing the expansion liquid 120, the overall mass of the anode sheet 100 is m1. After baking the anode sheet 100 in an environment at 80°C for five minutes, the overall mass of the anode sheet 100 is m2. The weight loss rate m of the anode sheet 100 satisfies m = (m1 - m2) / m1. The weight loss rate of the anode sheet 100 reflects the degree to which the bending section 111 absorbs the expansion liquid 120. When the bending section 111 of the anode sheet 100 absorbs too much expansion liquid 120, the expansion liquid 120 will dissolve most of the adhesive on the surface of the bending section 111, reducing the bonding ability of the bending section 111. This results in poor bonding of the various parts of the bending section 111, and after baking the anode sheet 100 at 80°C for five minutes, the bending section 111 will show powder shedding. In addition, if the bending section 111 of the anode sheet 100 absorbs too much expansion liquid 120, the baking time will also be longer, reducing the drying efficiency. In this embodiment, the weight loss rate of the anode sheet 100 is less than 0.5%. Under these conditions, the anode sheet 100 will not shed powder due to excessive absorption of expansion liquid 120, nor will it be difficult to dry, resulting in high drying efficiency.
[0034] In some embodiments, the radius of the bent segment 111 after bending is R, and the deviation between the theoretical length and the actual length of the bent segment 111 is Δ. The actual length of the bent segment 111 satisfies L = π / 2 * RΔ. When the anode sheet 100 is applied to the battery cell 1000, it needs to be wound. When the anode sheet 100 is wound evenly, the theoretical length of the bent segment 111 satisfies L = π / 2 * R. However, in actual operation, the anode sheet 100 may be wound unevenly, such as one layer being wound too tightly or too loosely, causing a deviation between the actual length and the theoretical length of the bent segment 111. After the anode sheet 100 is wound and applied to the battery cell 1000, the length of the bent segment 111 is measured. If the actual length of the bent segment 111 does not match the theoretical length, the length of the bent segment 111 needs to be adjusted. The adjusted actual length L satisfies L = π / 2 * RΔ.
[0035] Reference Figure 2This utility model embodiment also proposes a battery cell 1000, which includes an anode sheet 100, a diaphragm 200, and a cathode sheet 300 that are stacked and wound around each other. The diaphragm 200 is disposed between the anode sheet 100 and the cathode sheet 300. The anode sheet 100 is the anode sheet 100 described above. The battery cell 1000 is wound to form a straight region P and a corner region G. The straight section 112 is located in the straight region P, and the section to be bent 111 is located in the corner region G. Since this battery cell 1000 adopts all the technical solutions of all the above embodiments, it has at least all the technical effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.
[0036] This utility model embodiment also proposes a battery, which includes a casing and a battery cell 1000 as described in the foregoing embodiments, wherein the battery cell 1000 is disposed in the casing. Since this battery adopts all the technical solutions of all the above embodiments, it possesses at least all the technical effects brought about by the technical solutions of the above embodiments, and will not be elaborated further here.
[0037] This utility model embodiment also proposes a battery module, which includes a plurality of the aforementioned batteries. Since this battery module adopts all the technical solutions of all the above embodiments, it possesses at least all the technical effects brought about by the technical solutions of the above embodiments, and will not be elaborated further here.
[0038] The above description is only a part or preferred embodiment of this utility model. Neither the text nor the drawings should limit the scope of protection of this utility model. All equivalent structural transformations made using the content of this utility model specification and drawings under the overall concept of this utility model, or direct / indirect applications in other related technical fields, are included within the scope of protection of this utility model.
Claims
1. An anode sheet, characterized in that, Including the electrode body; The electrode body has a bending section and a straight section arranged alternately along its length direction. Each bending section is expanded, and the thickness of the bending section is greater than the thickness of the straight section. The section to be bent contains an expansion liquid that causes it to expand; the expansion liquid is deionized water.
2. The anode plate according to claim 1, characterized in that, The thickness expansion rate of the section to be bent is greater than 10%.
3. The anode plate according to claim 1, characterized in that, The droplet size of the deionized water is less than 30 μm.
4. The anode plate according to claim 1, characterized in that, The weight loss rate of the electrode body is less than 0.5%.
5. The anode plate according to claim 1, characterized in that, The radius of the segment to be bent after bending is R, the deviation between the theoretical length of the segment to be bent and the actual length of the segment to be bent is Δ, and the actual length of the segment to be bent is L=π / 2*RΔ.
6. A battery cell, characterized in that, It includes an anode sheet, a diaphragm, and a cathode sheet that are stacked and wound around each other, wherein the diaphragm is disposed between the anode sheet and the cathode sheet; Wherein, the anode sheet is the anode sheet as described in any one of claims 1-5, the battery cell is wound to form a straight area and a corner area, the straight section is located in the straight area, and the section to be bent is located in the corner area.
7. A battery, characterized in that, It includes a housing and a battery cell as described in claim 6, wherein the battery cell is disposed in the housing.
8. A battery module, characterized in that, It includes multiple batteries as described in claim 7.