Cathode plate, winding battery cell and battery

Abstract

The utility model discloses a cathode plate, a winding battery cell and a battery, and relates to the technical field of new energy batteries. The cathode plate provided by the utility model comprises a current collector and cathode active layers, wherein the cathode active layers are respectively coated on two sides of the current collector; the cathode plate is provided with a plurality of straight sections and a plurality of corner sections, the straight sections and the corner sections are alternately arranged, and each corner section is configured as follows: the cathode active layer on at least one side is provided with at least two liquid storage tanks and at least one liquid guide tank, the volume of the liquid storage tanks is larger than that of the liquid guide tank, and every two adjacent liquid storage tanks are communicated through the liquid guide tank. In the circulation process of the cathode plate, when the electrolyte in one of the liquid storage tanks is consumed or squeezed away, the adjacent liquid storage tanks supplement the electrolyte to the liquid storage tanks with less electrolyte through the liquid guide tanks, so that the situation that lithium is separated out on an interface at a corner area of a winding battery cell in the later circulation period is reduced, and the lithium ion battery cell is prevented from being damaged. And the service life of the lithium ion battery is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of new energy battery technology, and in particular to a cathode sheet, a wound cell and a battery. Background Technology

[0002] Lithium-ion batteries are widely used in various digital products and mobile devices due to their advantages such as high energy density, low self-discharge, wide operating temperature range, and no environmental pollution. A lithium-ion battery typically consists of a casing, a cell, and an electrolyte. The cell is housed in a sealed casing and immersed in the electrolyte, enabling it to undergo an electrochemical reaction to achieve charging and discharging. As a common cell structure, wound cells present significant interface challenges, particularly at corner areas, with continuously increasing charging rates.

[0003] A wound battery cell is formed by tightly bonding a cathode, anode, and separator together through winding. The electrodes at the corners of the wound cell are tightly bonded together. After long-term lithium-ion cycling, the electrolyte on the electrodes is gradually consumed. Simultaneously, the continuous expansion of the electrodes compresses the electrolyte at the corners. Therefore, in the later stages of cycling, abnormalities such as lithium deposition at the corners of the wound cell often occur, affecting the lifespan of the wound lithium-ion battery. Utility Model Content

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a cathode sheet that enables better wetting of the corner sections, thereby reducing lithium deposition at the corner areas of the wound cell during the later stages of cycling, and thus improving the lifespan of the lithium-ion battery.

[0005] This utility model also proposes a wound battery cell having the above-mentioned cathode sheet.

[0006] This utility model also proposes a battery having the above-mentioned wound battery cell.

[0007] The cathode sheet according to a first aspect embodiment of the present invention includes:

[0008] current collector;

[0009] A cathode active layer is coated on both sides of the current collector;

[0010] The cathode sheet has multiple straight sections and multiple corner sections, which are alternately arranged. Each corner section is configured such that at least one side of the cathode active layer has at least two liquid storage tanks and at least one liquid guiding tank. The volume of the liquid storage tanks is greater than the volume of the liquid guiding tanks, and adjacent liquid storage tanks are connected through the liquid guiding tanks.

[0011] The cathode sheet according to the embodiments of this utility model has at least the following beneficial effects:

[0012] When the electrolyte in one of the storage tanks is consumed or squeezed out, the adjacent storage tank replenishes the electrolyte in the tank with less electrolyte through a liquid guide channel. This ensures that the corner section of the cathode sheet maintains good wetting, thereby reducing lithium plating at the corner area during the later stages of cycling and improving the lifespan of the lithium-ion battery. This application uses a combination of storage tanks and liquid guide channels, providing a larger wetting range and better wetting effect. The liquid guide channel allows for electrolyte flow between different areas and reduces the impact on the energy density and structural strength of the cathode sheet. Compared to directly creating an entire groove for electrolyte storage, the cathode sheet of this application has a higher energy density and better structural strength. Furthermore, since both the storage tank and the liquid guide channel are located on the cathode sheet, this solves the problem of insufficient electrolyte at the corner area of ​​the wound cell. The groove also removes some of the cathode active material, indirectly reducing the lithium-ion concentration during cycling and further reducing the risk of lithium plating.

[0013] According to some embodiments of the present invention, the liquid storage tanks at the same corner segment are arranged at intervals along the width direction of the cathode sheet, and the liquid guiding channel extends along the width direction of the cathode sheet to connect adjacent liquid storage tanks.

[0014] According to some embodiments of the present invention, along the width direction of the cathode sheet, the outermost edge of the liquid storage tank is spaced apart from the edge of the cathode sheet.

[0015] According to some embodiments of the present invention, a plurality of liquid guiding channels are provided between two adjacent liquid storage tanks. Each liquid guiding channel is spaced apart and arranged side by side along the length direction of the cathode plate, and is respectively connected to the two liquid storage tanks.

[0016] According to some embodiments of the present invention, the two ends of the cathode sheet along its length direction are respectively set as the starting end and the ending end, and the length of the corner segment gradually increases along the direction from the starting end to the ending end, wherein the size of the liquid storage tank along the length direction of the cathode sheet gradually increases.

[0017] According to some embodiments of the present invention, the width of each of the liquid guiding grooves is from 10 μm to 500 μm.

[0018] According to some embodiments of the present invention, the depth of the liquid storage tank is 20% to 80% of the thickness of the cathode active layer.

[0019] A wound battery cell according to a second aspect of the present invention includes: an anode sheet, a diaphragm, and a cathode sheet as described in any one of the above embodiments; wherein the cathode sheet, the diaphragm, and the anode sheet are wound together to form the wound battery cell.

[0020] According to some embodiments of the present invention, the cathode sheet, after being wound, has a relatively inner side facing the center of the wound cell and a relatively outer side away from the center of the wound cell. The corner section of the cathode sheet is configured such that the cathode active layer on the relatively inner side is provided with a liquid storage tank and a liquid guiding tank.

[0021] A battery according to a third aspect of the present invention includes a housing and a wound cell as described in the above embodiments, the wound cell being located within the housing.

[0022] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0024] Figure 1 This is a schematic diagram of the structure of the cathode sheet in an embodiment of the present invention;

[0025] Figure 2 for Figure 1 Enlarged view of region A in the middle;

[0026] Figure 3 for Figure 1 Cross-sectional schematic diagram along the BB direction;

[0027] Figure 4 This is a schematic diagram of the structure of the wound battery cell according to an embodiment of the present invention.

[0028] Figure label:

[0029] Cathode plate 10;

[0030] Current collector 100;

[0031] Cathode active layer 200; straight section 210; corner section 220; liquid storage tank 221; liquid guiding tank 222; Detailed Implementation

[0032] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0033] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0034] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0035] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0036] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0037] Lithium-ion batteries are widely used in various digital products and mobile devices due to their advantages such as high energy density, low self-discharge, wide operating temperature range, and no environmental pollution. A lithium-ion battery typically consists of a casing, a cell, and an electrolyte. The cell is housed in a sealed casing and immersed in the electrolyte, enabling it to undergo an electrochemical reaction to achieve charging and discharging. As a common cell structure, wound cells present significant interface challenges, particularly at corner areas, with continuously increasing charging rates.

[0038] A wound battery cell is formed by tightly bonding a cathode, anode, and separator together through winding. The electrodes at the corners of the wound cell are tightly bonded together. After long-term lithium-ion cycling, the electrolyte on the electrodes is gradually consumed. Simultaneously, the continuous expansion of the electrodes compresses the electrolyte at the corners. Therefore, in the later stages of cycling, abnormalities such as lithium deposition at the corners of the wound cell often occur, affecting the lifespan of the wound lithium-ion battery.

[0039] To solve the above problems, such as Figures 1 to 3 As shown, the first aspect of this application provides a cathode sheet 10, which includes a current collector 100 and a cathode active layer 200. It is understood that the current collector 100 of the cathode sheet 10 is typically made of aluminum foil, or it may be made of other metal foils or composite foils. The cathode active layer 200 is formed by spraying a cathode active material onto the current collector 100. The cathode active layer 200 is coated on both sides of the current collector 100, and after drying and compaction, the cathode sheet 10 is formed.

[0040] The cathode plate 10 has multiple straight sections 210 and multiple corner sections 220. After the cathode plate 10, the diaphragm, and the anode plate are wound to form a battery cell, the wound battery cell includes straight regions and corner regions. It should be explained that straight regions refer to areas where the electrode is in a straight line, and corner regions refer to areas where the electrode is in an arc shape. After winding, the straight sections 210 of the cathode plate 10 are located in the straight regions of the wound battery cell, and the corner sections 220 of the cathode plate 10 are located in the corner regions of the wound battery cell. Therefore, based on the straight and corner regions of the wound battery cell, the distribution pattern of the straight sections 210 and corner sections 220 on the cathode plate 10 can be obtained. Figure 1 The diagram shows the structure of the cathode sheet 10 in its unwound state. Straight sections 210 and corner sections 220 are alternately arranged on the cathode sheet 10. The positions of the straight sections 210 and corner sections 220 are determined by calculation when the cathode sheet 10 is not yet wound. It should be noted that there is actually no clear dividing line between the straight sections 210 and the corner sections 220. Figure 1 The dashed lines shown are only used to illustrate the straight section 210 and the corner section 220.

[0041] Among them, such as Figure 1 and Figure 2As shown, the corner section 220 of the cathode plate 10 is configured such that at least one side of the cathode active layer 200 is provided with at least two liquid storage tanks 221 and at least one liquid guiding tank 222, with adjacent liquid storage tanks 221 connected by the liquid guiding tank 222. It should be noted that the volume of the liquid storage tank 221 is larger than the volume of the liquid guiding tank 222. In the illustrated embodiment, the width of the liquid storage tank 221 is much larger than the width of the liquid guiding tank 222. The liquid storage tank 221 can store electrolyte and diffuse the electrolyte into the active material in the surrounding area, facilitating better wetting of the electrode plate. The liquid guiding tank 222 allows the electrolyte to flow between adjacent liquid storage tanks 221. It should be noted that the liquid guiding tank 222 also functions as a liquid storage tank, and the liquid storage capacity of the liquid storage tank 221 is much greater than that of the liquid guiding tank 222.

[0042] Therefore, when the electrolyte in one of the storage tanks 221 is consumed or squeezed out, the adjacent storage tank 221 replenishes the electrolyte in the storage tank 221 with less electrolyte through the liquid guiding channel 222, so that the corner section 220 of the cathode sheet 10 can always obtain a good wetting effect, thereby reducing the occurrence of lithium plating at the interface in the corner area of ​​the wound cell in the later stage of the cycle, and thus improving the life of the lithium-ion battery.

[0043] It should be noted that this application employs a combination of a storage tank 221 and a guiding tank 222, which provides a larger wetting range and better wetting effect. The guiding tank 222 enables the flow of electrolyte between different areas and reduces the impact on the energy density and structural strength of the cathode plate 10. Compared to a solution that directly creates an entire groove for electrolyte storage, the cathode plate 10 of this application achieves higher energy density and better structural strength.

[0044] In addition, it should be noted that the liquid storage tank 221 and the liquid guiding tank 222 of this application are both disposed on the cathode plate 10. While solving the problem of insufficient electrolyte in the corner area of ​​the wound cell, the slotting removes some of the cathode active material, thereby indirectly reducing the concentration of lithium ions during the cycle and further reducing the risk of lithium plating.

[0045] In some embodiments, the liquid storage tanks 221 at the same corner segment 220 are arranged at intervals along the width direction of the cathode plate 10, and the liquid guiding channels 222 extend along the width direction of the cathode plate 10 to connect adjacent liquid storage tanks 221. Figure 1 and Figure 2As shown, three spaced-apart liquid storage tanks 221 are provided at a corner section 220. The liquid storage tanks 221 are spaced apart along the width direction of the cathode plate 10, and adjacent liquid storage tanks 221 are connected by three parallel liquid guiding channels 222. Thus, the liquid storage tanks 221 and liquid guiding channels 222 basically cover the corner section 220 along the width direction of the cathode plate 10, greatly improving the wetting effect of the electrolyte at the corner section 220.

[0046] Furthermore, along the width direction of the cathode plate 10, the edge of the outermost liquid storage tank 221 is spaced apart from the edge of the cathode plate 10. For example... Figure 4 Taking this as an example, the outermost liquid storage tank 221 refers to the two liquid storage tanks 221 at the leftmost and rightmost ends shown in the figure. These two liquid storage tanks 221 do not extend to the edge of the cathode plate 10. The left edge of the leftmost liquid storage tank 221 is spaced apart from the left edge of the cathode plate 10, and the right edge of the rightmost liquid storage tank 221 is spaced apart from the right edge of the cathode plate 10. Thus, the width of the entire area where the liquid storage tanks 221 and the liquid guiding tanks 222 are arranged is smaller than the width of the cathode plate 10, so as to avoid excessive impact on the structural strength of the cathode plate 10.

[0047] Furthermore, in some embodiments (not shown in the figure), the outermost liquid storage tank 221 may also be connected to a flow channel. One end of the flow channel is connected to the outermost liquid storage tank 221, and the other end extends to the edge of the cathode plate 10. This allows the electrolyte outside the cathode plate 10 to flow more easily into the liquid storage tank 221 through the flow channel, so that the cathode plate 10 has a better wetting effect.

[0048] In some embodiments, such as Figure 2 As shown, multiple liquid guiding channels 222 are provided between two adjacent liquid storage tanks 221. Each liquid guiding channel 222 is spaced apart and arranged side by side along the length direction of the cathode plate 10. The two ends of each liquid guiding channel 222 are connected to the two liquid storage tanks 221 respectively. The number of liquid guiding channels 222 can be adjusted according to the dimension of the liquid storage tank 221 along the length direction of the cathode plate 10 (hereinafter referred to as the length dimension of the liquid storage tank 221 for ease of description). If the length dimension of the liquid storage tank 221 is large, the number of liquid guiding channels 222 can be increased appropriately; if the length dimension of the liquid storage tank 221 is small, the number of liquid guiding channels 222 can be decreased appropriately.

[0049] In some embodiments, for ease of description, the two ends of the cathode sheet 10 along its length are respectively designated as the starting end and the ending end. It can be understood that the starting end refers to the end where winding begins when the cathode sheet 10, diaphragm, and anode sheet are wound. After winding, the starting end is located at the center of the wound cell, and correspondingly, the ending end is located at the outer periphery of the wound cell after winding. As the number of winding layers increases, the length of the relatively outer corner segment 220 gradually increases. Therefore, along the direction from the starting end to the ending end of the cathode sheet 10, the length of the corner segment 220 gradually increases. To match the gradually increasing corner segment 220, the length of the liquid storage tank 221 on each corner segment 220 also gradually increases along the direction from the starting end to the ending end. Correspondingly, the number of liquid guiding tanks 222 can also be increased accordingly.

[0050] Alternatively, in other embodiments, for the corner segment 220 with gradually increasing length, multiple sets of liquid storage tanks 221 and liquid guiding tanks 222 can be provided on the same corner segment 220. Each set of liquid storage tanks 221 and liquid guiding tanks 222 is spaced apart along the length direction of the cathode plate 10. Each set of liquid storage tanks 221 and liquid guiding tanks 222 includes at least two liquid storage tanks 221 and at least one liquid guiding tank 222.

[0051] In some embodiments, the width of the liquid guiding groove 222 is in the range of 10 μm to 500 μm, so that the structural strength and energy density of the cathode plate 10 are not excessively affected while the electrolyte flows through it.

[0052] In some embodiments, the depth of the liquid storage tank 221 is 20% to 80% of the thickness of the cathode active layer 200. This provides good liquid storage capacity without excessively affecting the structural strength and energy density of the cathode sheet 10, and prevents the foil from being exposed to avoid corrosion of the current collector 100.

[0053] A second aspect of this application provides a wound battery cell, comprising an anode sheet, a separator, and a cathode sheet 10 as described in any of the above embodiments. The anode sheet, separator, and cathode sheet 10 are wound together to form the wound battery cell. The separator is disposed between the cathode sheet 10 and the anode sheet to separate them and prevent direct contact that could lead to a short circuit. Simultaneously, the separator allows lithium ions to move freely, thereby ensuring normal current transmission within the battery cell.

[0054] In such Figure 4In the wound cell shown, it can be understood that after the cathode sheet 10 is wound, it has a relatively inner side facing the center of the wound cell and a relatively outer side away from the center of the wound cell. From the relatively inner side to the relatively outer side, the arc diameter of the corner region of the wound cell gradually increases. Taking any corner region of the cathode sheet 10 as an example, its inner side has an anode sheet with a smaller arc diameter. The cathode active layer 200 on the relatively inner side of the cathode sheet 10 reacts with the anode sheet on the inner side of the cathode sheet 10. Therefore, the area of ​​the cathode active layer 200 is often larger than the area of ​​the anode active layer. When the number of lithium ions deposited on the cathode exceeds the number of lithium insertion sites on the anode, lithium plating problems are likely to occur. The outer side has an anode sheet with a larger arc diameter. The cathode active layer 200 on the relatively outer side of the cathode sheet 10 reacts with the anode sheet on the outer side of the cathode sheet 10. The area of ​​the cathode active layer 200 is smaller than the area of ​​the anode active layer. The redundancy of the lithium insertion sites on the anode makes lithium plating reactions less likely.

[0055] Therefore, the liquid storage tank 221 and the liquid guiding tank 222 can be set on the relatively inner cathode active layer 200. On the one hand, this reduces the number of lithium ions on the relatively inner cathode active layer 200, thereby reducing the probability of lithium plating problems. On the other hand, it can reduce the impact of slotting on the cathode active layer 200 on the battery energy density.

[0056] A third aspect of this application also proposes a battery comprising a casing and a wound cell as described in the above embodiments. The wound cell is disposed within the casing, and the casing is filled with electrolyte. It is understood that this battery can be a pouch battery or a steel-cased battery, and can be applied in fields such as 3C digital products, home appliances, and new energy vehicles. Since the battery of this embodiment includes the wound cell of any of the above embodiments, the battery of this embodiment has the beneficial effects of the above embodiments, which will not be repeated here.

[0057] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A cathode plate, characterized in that, include: current collector; A cathode active layer is coated on both sides of the current collector; The cathode sheet has multiple straight sections and multiple corner sections, which are alternately arranged. Each corner section is configured such that at least one side of the cathode active layer has at least two liquid storage tanks and at least one liquid guiding tank. The volume of the liquid storage tanks is greater than the volume of the liquid guiding tanks, and adjacent liquid storage tanks are connected through the liquid guiding tanks.

2. The cathode sheet according to claim 1, characterized in that, The liquid storage tanks at the same corner segment are arranged at intervals along the width direction of the cathode plate, and the liquid guiding channel extends along the width direction of the cathode plate to connect the adjacent liquid storage tanks.

3. The cathode sheet according to claim 2, characterized in that, Along the width direction of the cathode sheet, the outermost edge of the liquid storage tank is spaced apart from the edge of the cathode sheet.

4. The cathode sheet according to claim 1, characterized in that, Multiple liquid guiding channels are provided between two adjacent liquid storage tanks. Each liquid guiding channel is spaced apart and arranged side by side along the length of the cathode plate, and is connected to the two liquid storage tanks respectively.

5. The cathode sheet according to claim 1, characterized in that, The two ends of the cathode sheet along its length are respectively designated as the starting end and the ending end. The length of the corner segment gradually increases along the direction from the starting end to the ending end, wherein the dimension of the liquid storage tank gradually increases along the length of the cathode sheet.

6. The cathode sheet according to claim 1, characterized in that, The width of each of the described liquid guiding grooves ranges from 10 μm to 500 μm.

7. The cathode sheet according to claim 1, characterized in that, The depth of the storage tank is 20% to 80% of the thickness of the cathode active layer.

8. A wound battery cell, characterized in that, include: The cathode plate as described in any one of claims 1 to 7; Diaphragm; Anode plate; The cathode sheet, the diaphragm, and the anode sheet are wound together to form the wound battery cell.

9. The wound battery cell according to claim 8, characterized in that, After being wound, the cathode sheet has a relatively inner side facing the center of the wound cell and a relatively outer side away from the center of the wound cell. The corner section of the cathode sheet is configured such that the cathode active layer on the relatively inner side is provided with a liquid storage tank and a liquid guiding tank.

10. A battery, characterized in that, include: case; The wound cell as described in claim 8 or 9, wherein the wound cell is located within the housing.

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