Patent Application
20250054995
The present disclosure relates to the field of batteries, and specifically relates to an electrode plate and a battery including the electrode plate.
Lithium-ion batteries are currently widely used in fields such as consumer electronics, electric vehicles, and energy storage. Lithium-ion batteries used in consumer electronics products represented by mobile phones are mainly pouch lithium-ion batteries. During a preparation process of a battery, a positive tab and a negative tab are welded respectively on tab welding regions on a positive electrode current collector and a negative electrode current collector as current-conducting devices. In addition, in order to prevent tab burrs from piercing a separator so as not to cause a short circuit between a positive electrode and a negative electrode, an adhesive paper is applied on the tabs for protection. The positive electrode, the separator, and the negative electrode are then wound into a jelly roll. Especially when a width of the battery is narrow (generally ranging from 25 mm to 35 mm), the tab welding region is close to a winding arc region, so that the adhesive paper is located on the winding arc region. This may easily cause the adhesive paper to fold, resulting in poor flatness near the tabs, and further leading to problems of a poor battery interface and lithium deposition.
Therefore, there is a need to find a method to improve a problem of poor battery flatness.
The objective of the present disclosure is to overcome problems of a poor interface and lithium deposition caused by poor flatness near a tab in the prior art, by providing an electrode plate and a battery including the electrode plate. The electrode plate in the present disclosure can fully solve a problem of poor flatness near a tab, and can effectively solve a lithium deposition problem of a lithium-ion battery caused by the poor flatness near the tab.
A first aspect of the present disclosure provides an electrode plate. The electrode plate includes a current collector, a tab, a coating layer, and an adhesive paper; a tab welding region and a paste coating region are disposed on the current collector; the tab is disposed in the tab welding region, and the coating layer is disposed in the paste coating region; the electrode plate is divided into a plurality of planar regions and curved surface regions that are alternately disposed, the curved surface region is located in a winding bending portion, and the tab welding region is located in the planar region; the adhesive paper covers the tab welding region, partially covers a planar region in which the tab welding region is located, crosses over an adjacent curved surface region on one side, and partially covers an adjacent planar region; and a projection of the adhesive paper on the adjacent planar region has a dimension L1 in a length direction of the electrode plate, and 0<L1≤10 mm.
Based on the foregoing technical solutions, the present disclosure has at least the following advantages over the conventional technology.
Firstly, a position of an adhesive paper applied to the electrode plate of the present disclosure crosses over a curved surface region of a winding bending portion, thereby reducing occurrence of the adhesive paper folding when the electrode plate is wound and improving flatness near a tab.
Secondly, a size of the adhesive paper applied to the electrode plate of the present disclosure is moderate, which can completely cover a tab welding region and reduce adverse effects on electrical performance.
An endpoint and any value of the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values shall be understood to include values close to these ranges or values. For a numerical range, one or more new numerical ranges may be obtained in combination with each other between endpoint values of respective ranges, between endpoint values of respective ranges and individual point values, and between individual point values, and these numerical range should be considered as specifically disclosed herein.
Specific implementations of the present disclosure are described below in detail. It should be understood that the specific implementations described herein are merely used for the purposes of illustrating and explaining the present disclosure, rather than limiting the present disclosure.
According to an electrode plate of the specific embodiment of the present disclosure, the electrode plate is exemplarily described below with reference to the accompanying drawings.
A first aspect of the present disclosure provides an electrode plate. As shown in
In the present disclosure, the electrode plate and the separator are assembled by winding to form a battery, and the electrode plate forms a planar region and a curved surface region during the winding process, and the curved surface region is located at a winding bending portion.
In the present disclosure, the term “length direction” has a conventional meaning in the art. The “length direction” of the electrode plate is a direction of a long side of the electrode plate.
It may be understood that a smaller area of the electrode plate covered by the adhesive paper leads to a larger operation difficulty, and makes it more likely that incomplete coverage occurs that may cause a short circuit between a positive electrode and a negative electrode, thereby reducing safety performance of the battery. In contrast, a larger area of the electrode plate covered by the adhesive paper leads to a smaller operation difficulty, and makes it less likely that incomplete coverage occurs. However, as the area of the electrode plate covered by the adhesive paper increases, energy density of the battery also decreases. Therefore, it is required to minimize reduction in energy density caused by an excessive adhesive paper while ensuring safety performance of the battery.
In an example, 0.1 mm≤L1≤8 mm.
In an example, 0.3 mm≤L1≤5 mm.
In an example, the tab welding region is disposed at a region that does not belong to two ends of the current collector in a length direction. The tab welding region is disposed at a region that does not belong to two ends of the current collector in a length direction, that is, the tab is located in a middle region in the length direction of the current collector. In this case, the electrode plate is a central tabprocess structure (CTP structure).
The inventors of the present disclosure find that when one side surface of the current collector includes two or more coating layers, there is misalignment of the coating layers near the tab welding region, resulting in a difference between a thickness near the tab welding region and a thickness at another location of the electrode plate, further deteriorating flatness near the tab, and causing lithium deposition. The thickness difference region of the coating layers near the tab welding region is controlled, so that the flatness near the tab can be significantly improved, and the problem of lithium deposition in the battery can be improved.
In a specific implementation, as shown in
In another specific implementation, L2≤5 mm.
In another specific implementation, as shown in
In an example, the adhesive paper covers the coating layer adjacent to the tab welding region.
The electrode plate in the present disclosure can effectively ensure that thicknesses of coating layers near the tab welding region are consistent, thereby improving flatness near the tab.
A dimension of the tab welding region in a width direction of the current collector may account for 10% to 50% of a width of the current collector, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%.
In an example, a dimension of the tab welding region in a width direction of the current collector accounts for 15% to 30% of a width of the current collector.
The adhesive paper can not only prevent tab burrs from piercing a separator so as not to cause a short circuit between a positive electrode and a negative electrode, but also can cover the tab welding region to prevent a short circuit caused by contact between the positive electrode and the negative electrode. It may be understood that both the dimension of the adhesive paper in the length direction of the current collector and the dimension of the adhesive paper in the width direction of the current collector can affect safety performance and electrochemical performance of the battery. When the dimension of the adhesive paper in the width direction of the current collector is small, the adhesive paper may not be able to completely cover the tab welding region in the width direction of the current collector during adhesive paper application, which may cause a short circuit between the positive electrode and the negative electrode. When the dimension of the adhesive paper in the width direction of the current collector is large, energy density of the battery may be affected, and the electrochemical performance of the battery is adversely affected. Therefore, it is required to minimize reduction in energy density caused by an excessive adhesive paper while ensuring safety performance of the battery.
In an example, a dimension of the adhesive paper in a width direction of the current collector is less than a width of the current collector.
A dimension of the adhesive paper in a width direction of the current collector may be 1 mm to 10 mm, for example, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm, greater than a dimension of the tab welding region in the width direction of the current collector.
In an example, a dimension of the adhesive paper in a width direction of the current collector is 2 mm to 5 mm greater than a dimension of the tab welding region in the width direction of the current collector.
The adhesive paper may be a conventional adhesive paper in the art, for example, acrylic adhesive paper or rubber adhesive paper.
A thickness of the adhesive paper may range from 4 μm to 20 μm, for example, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm.
In an example, a thickness of the adhesive paper ranges from 6 μm to 12 μm.
A second aspect of the present disclosure provides a battery, and the battery includes the electrode plate according to the first aspect of the present disclosure.
In an example, the electrode plate is a positive electrode plate and/or a negative electrode plate.
Except for the electrode plate, all materials and a preparation method of the battery may be performed in a manner in the art. In this way, flatness can be improved.
The battery further includes a separator and an electrolyte solution.
For example, the separator includes a base material layer and a separator coating layer applied on both sides of the base material layer; the base material layer includes at least one of a polyethylene film, a polypropylene film, a mixed film of polyethylene and polypropylene (for example a mass ratio of polyethylene to polypropylene is 2:1), or a polyimide film; the separator coating layer includes a ceramic layer and/or an adhesive layer; the ceramic layer includes aluminum oxide and/or boehmite; and the adhesive layer includes polyvinylidene fluoride.
For example, the electrolyte solution includes a combination of ethylene carbonate and dimethyl carbonate (for example a mass ratio of ethylene carbonate to dimethyl carbonate is 2:3) and 0.8 mol/L lithium hexafluorophosphate.
The following describes the present disclosure in detail by using embodiments. The embodiments described in the present disclosure are merely some, but not all of the embodiments of the present disclosure. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts fall within the protection scope of the present disclosure.
In the following examples, unless otherwise specified, all materials used were commercially available analytical reagents.
The following examples were used to describe a battery in the present disclosure.
Preparation of the battery in the present disclosure includes at least the following steps.
Differences between Example 1 to Example 9 in the present disclosure and comparative examples lied in a size and an application location of an adhesive paper, and a dimension of a thickness difference region of a coating layer in a length direction of an electrode plate. Details were shown in Table 1, where “positive electrode plate L2” referred to a dimension of a thickness difference region of a coating layer of a positive electrode plate in a length direction of the electrode plate, and the rest of the data referred to sizes and application locations of adhesive papers on the positive electrode plate and the negative electrode plate.
A difference between Example 10 and Example 1 in the present disclosure lied in that in Example 10, three coating layers were disposed outside a current collector of a positive electrode plate. Details are as follows.
A wound jelly roll was disassembled, and a positive electrode plate, a negative electrode plate, and a separator were separated, and a folding status of a protective adhesive paper in a welding region of the electrode plate was observed.
In a 25±3° C. environment, a battery was charged to 4.45 V at 1.5C, charged at a constant voltage to a cut-off current of 0.05C, and then discharged to 3.0 V at a rate of 0.5C. Charge and discharge steps were repeated 20 times, and then the battery was charged to 4.45 V at 1.5C, and charged at a constant voltage to a cut-off current of 0.05C. Then, in a dry environment with a dew point below −30° C., the battery was dissected, and a lithium deposition status of the battery was determined by observing whether there was lithium deposition on a negative electrode plate and a separator.
1.5C/0.5C charge-discharge cycle: The battery was charged to 4.45 V at 1.5C, charged at a constant voltage to 0.05C, and then discharged to 3.0 V at 0.5C. A capacity of each discharge was recorded. An initial discharge capacity was denoted as C0, a discharge capacity after 500 cycles was C500, and then, a cycling capacity retention rate F=C500/C0.
The test results were recorded in Table 2.
It may be learned from Table 2 that, compared with the comparative examples, the battery in the present disclosure does not have adhesive paper folding at the tab, there is no lithium deposition phenomenon at the tab, and the capacity retention rate after 500 cycles at room temperature is significantly improved. The battery prepared with the electrode plate in the present disclosure can improve lithium deposition caused by poor flatness near the tab while reducing adverse effects on electrical performance.
The foregoing describes in detail a preferred implementation of the present disclosure. However, the present disclosure is not limited thereto. Within the scope of the technical concepts of the present disclosure, various simple variations may be implemented to the technical solutions of the present disclosure, including combinations of technical features in any other suitable manner. These simple variations and combinations shall also be considered as the disclosure of the present disclosure and shall fall within the protection scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202222457608.X | Sep 2022 | CN | national |
The present disclosure is a continuation-in-part of International Application No. PCT/CN2023/103258, filed on Jun. 28, 2023, which claims priority to Chinese Patent Application No.202222457608.X, filed on Sep. 15, 2022. Both of the aforementioned applications are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2023/103258 | Jun 2023 | WO |
| Child | 18923612 | US |
