Special-shaped pole piece and battery
By creating rectangular through holes on the rectangular positive and negative electrode plates of the lithium-ion battery, the problem of poor electrolyte wetting effect is solved, the energy density and fast charging performance of the battery are improved, and the service life is extended.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-23
- Publication Date
- 2026-04-14
AI Technical Summary
In existing lithium-ion batteries with high energy density designs, the electrolyte wetting effect is poor, resulting in a long lithium-ion transport path and hindering battery performance. This is especially true when the width of the negative electrode is greater than 150mm, which further affects the discharge capacity and service life.
Rectangular positive and negative electrode sheets are used, and rectangular through holes are made on them. The sheets are stacked to form a cell, and the cell is placed in a casing to make an irregularly shaped battery, which improves the wettability of the electrolyte to the electrode sheets and separator.
It improves the wetting effect of the electrolyte, maintains a high energy density, and enhances the battery's fast charging and cycle performance, while reducing interface resistance and extending its service life.
Smart Images
Figure CN224123346U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of lithium-ion battery technology, specifically to an irregularly shaped electrode and a battery. Background Technology
[0002] In existing lithium-ion battery production methods, after assembly and electrolyte filling, batteries need to be left to stand for a period of time before pre-charging. The purpose of this post-filling stand is to allow the electrolyte to fully wet the positive and negative electrode materials and separator within the battery. During the initial pre-charge, lithium ions react with the electrolyte on the surface of the negative electrode material to form an SEI film. The quality of this SEI film formation directly affects the subsequent performance of the lithium-ion battery. The effectiveness of electrolyte wetting directly impacts the quality of the SEI film. If the electrolyte wetting is poor, the ion transport path becomes longer, hindering the shuttle of lithium ions between the positive and negative electrodes. Electrodes not in contact with the electrolyte cannot participate in the battery's electrochemical reaction, leading to increased interfacial resistance and affecting the battery's discharge capacity and lifespan. Furthermore, the current development of power batteries still pursues high energy density, employing higher areal density and compaction density in electrochemical design, resulting in increasingly thicker electrode sheets and larger lengths and widths in cell size design. Generally, the longest part of the negative electrode sheet is considered as the length L, and the shorter direction as the width W. If the width W of the negative electrode sheet is greater than 150mm, and the length-to-width ratio of the negative electrode sheet meets the requirement of 80% ≤ W / L ≤ 100%, then the electrolyte needs a longer time to penetrate from the periphery to the center of the negative electrode sheet, resulting in a poorer wetting effect. This will also lead to more prominent cell failure problems. Therefore, there is an urgent need for a battery with good wetting effect. Utility Model Content
[0003] The purpose of this utility model is to overcome the shortcomings of the prior art and provide an irregularly shaped electrode sheet and battery. The positive and negative electrode sheets are rectangular and rectangular through holes are opened on the positive and negative electrode sheets. The positive and negative electrode sheets are stacked to form a battery cell. The battery cell is placed in the casing to form an irregularly shaped battery. This effectively improves the wettability of the electrolyte to the positive and negative electrode sheets and separator in the core pack. The wettability is good and the energy density can be maintained without significant reduction.
[0004] The purpose of this utility model is achieved through the following technical measures: an irregularly shaped electrode sheet, comprising a positive electrode sheet and a negative electrode sheet, both of which are rectangular electrode sheets. The rectangular width of the negative electrode sheet is greater than or equal to 150 mm and less than or equal to 340 mm, and the ratio of the width to the length of the rectangle is greater than or equal to 0.8. The top of the positive electrode sheet is provided with a positive electrode tab, and the top of the negative electrode sheet is provided with a negative electrode tab. Both the positive and negative electrode sheets are provided with rectangular through holes. The four sides of the rectangular through holes are parallel to the four sides of the rectangular electrode sheets, and the maximum distance between the four sides of the rectangular through holes and the four sides of the rectangular electrode sheets parallel to them is less than or equal to 100 mm.
[0005] In some embodiments, the center point of the rectangular through hole coincides with the center point of the rectangular electrode sheet.
[0006] In some embodiments, the rectangular electrode area of the positive electrode is smaller than that of the rectangular electrode area of the negative electrode.
[0007] In some embodiments, the area of the rectangular through hole on the positive electrode is greater than the area of the rectangular through hole on the negative electrode.
[0008] In some embodiments, the edge of the rectangular through hole in the width direction is parallel to the edge of the rectangular electrode in the width direction.
[0009] An irregularly shaped battery includes a casing, and a battery cell is disposed inside the casing. The battery cell includes multiple separators stacked together and multiple positive and negative electrode plates. The separators are stacked between the positive and negative electrode plates. The separators are rectangular separators with rectangular through holes. The shape of the casing matches the shape of the battery cell.
[0010] In some embodiments, the area of the separator is larger than the area of the rectangular electrode of the negative electrode, and the area of the rectangular through hole on the separator is smaller than the area of the rectangular through hole on the negative electrode.
[0011] In some embodiments, the plurality of diaphragms are independent of each other, or the plurality of diaphragms are connected sequentially.
[0012] In some embodiments, when the positive electrode and the negative electrode are stacked, the positive electrode tab and the negative electrode tab are spaced apart at the top of the cell.
[0013] Compared with the prior art, the beneficial effects of this utility model are as follows: This utility model uses rectangular positive and negative electrode sheets, opens rectangular through holes on the positive and negative electrode sheets, stacks the positive and negative electrode sheets to form a battery cell, and places the battery cell in the casing to form an irregularly shaped battery. This effectively improves the wettability of the electrolyte to the positive and negative electrode sheets and the separator in the core pack. Moreover, compared with rectangular batteries of the same size without rectangular through holes, this utility model can still maintain a high energy density.
[0014] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the negative electrode.
[0016] Figure 2 This is a schematic diagram of the positive electrode structure.
[0017] Figure 3 This is a schematic diagram of the battery structure in Example 1.
[0018] Figure 4 This is a schematic diagram of the battery structure in Comparative Example 1.
[0019] Among them, 1. positive electrode tab, 2. negative electrode tab, 3. rectangular through hole, 4. shell. Detailed Implementation
[0020] like Figures 1 to 4 As shown, an irregularly shaped electrode includes a positive electrode and a negative electrode, both of which are rectangular. The rectangular width W of the negative electrode satisfies 150 ≤ W ≤ 340 mm, and the ratio of the width W to the length L satisfies W / L ≥ 0.8. The positive electrode has a positive tab 1 at its top, and the negative electrode has a negative tab 2 at its top. Both the positive and negative electrodes have rectangular through holes 3. Specifically, when the positive and negative electrodes are stacked, the positions of the rectangular through holes 3 on the positive and negative electrodes correspond. The four edges of the rectangular through hole 3 are parallel to the four edges of the rectangular electrode, and the maximum value D of the distance D from the four edges of the rectangular through hole 3 to the four edges of the rectangular electrode it is parallel to is less than or equal to 100 mm.
[0021] In some embodiments, the center point of the rectangular through-hole 3 coincides with the center point of the rectangular electrode. That is, the rectangular through-hole 3 is located at the center of the rectangular electrode. In the electrode width W direction, the distance between the two edges of the rectangular through-hole 3 and the two edges of the rectangular electrode in the W direction is equal. In the electrode length L direction, the distance between the two edges of the rectangular through-hole 3 and the two edges of the rectangular electrode in the L direction is also equal. The rectangular through-hole 3 being located at the center of the electrode facilitates uniform wetting of the electrode by the electrolyte, resulting in more uniform current flow during charging and discharging, thus making the interface performance of the entire battery more uniform.
[0022] In some embodiments, the rectangular electrode area of the positive electrode is smaller than that of the rectangular electrode of the negative electrode. Specifically, the outer perimeter of the positive electrode is smaller than that of the negative electrode, that is, the length L and width W of the positive electrode are smaller than the length L and width W of the negative electrode, so that when the positive and negative electrodes are stacked, the periphery of the negative electrode can protrude beyond the periphery of the positive electrode. The specific dimensional differences in length L and width W between the positive and negative electrodes can be set according to conventional dimensional differences known to those skilled in the art. For example, the dimensional differences between the length L and width W of the negative electrode and those of the positive electrode are both 4 mm.
[0023] In some embodiments, the area of the rectangular through-hole 3 on the positive electrode sheet is larger than the area of the rectangular through-hole 3 on the negative electrode sheet. Specifically, the outer perimeter of the rectangular through-hole 3 on the positive electrode sheet is larger than the outer perimeter of the rectangular through-hole 3 on the negative electrode sheet, that is, the length L and width W of the rectangular through-hole 3 on the positive electrode sheet are larger than the length L and width W of the rectangular through-hole 3 on the negative electrode sheet. This allows the periphery of the rectangular through-hole 3 on the negative electrode sheet to protrude beyond the periphery of the rectangular through-hole 3 on the positive electrode sheet when the positive and negative electrode sheets are stacked, thereby enabling the negative electrode sheet to completely cover the positive electrode sheet. The specific size difference can be set according to the size difference between positive and negative electrode sheets well known to those skilled in the art, or the size difference of the rectangular through-hole can be set to the same value as the size difference between the positive and negative electrode sheets. For example, the size difference of the length L and width W of the positive and negative electrode sheets, as well as the size difference of the length L and width W of the rectangular through-hole 3 on the positive and negative electrode sheets, can both be set to 4 mm.
[0024] In some embodiments, the edge of the rectangular through-hole 3 in the width W direction is parallel to the edge of the rectangular electrode in the width W direction, and the edge of the rectangular through-hole 3 in the length L direction is parallel to the edge of the rectangular electrode in the length L direction. The width W of the rectangular through-hole 3 corresponds to the width W of the rectangular electrode, and the length L of the rectangular through-hole 3 corresponds to the length L of the rectangular electrode. This minimizes the distance D between the parallel edges of the rectangular through-hole 3 and the edges of the rectangular electrode, thereby facilitating the wetting of the electrode by the electrolyte.
[0025] An irregularly shaped battery includes a casing 4, within which a battery cell is disposed. The battery cell includes multiple stacked separators and multiple positive and negative electrode plates. The separators are stacked between the positive and negative electrode plates, separating them. The separators are rectangular and have rectangular through-holes 3. The positions of the rectangular through-holes 3 on the separators correspond to the positions of the rectangular through-holes 3 on the positive and negative electrode plates. The shape of the casing 4 matches the shape of the battery cell. When the battery cell is assembled into a battery within the casing 4, the battery has a rectangular through-hole 3 at its center.
[0026] In some embodiments, the area of the separator is larger than the area of the rectangular electrode of the negative electrode, and the area of the rectangular through-hole 3 on the separator is smaller than the area of the rectangular through-hole 3 on the negative electrode. When the positive electrode and the negative electrode are stacked, the periphery of the separator may protrude beyond the periphery of the negative electrode, and the periphery of the rectangular through-hole 3 on the separator may protrude beyond the periphery of the rectangular through-hole 3 on the negative electrode. The specific dimensional differences between the length L and width W of the negative electrode and the separator can be set according to conventional dimensional differences known to those skilled in the art. The specific dimensional differences between the rectangular through-hole 3 on the separator and the rectangular through-hole 3 on the negative electrode can be set according to the dimensional differences between the separator and the negative electrode known to those skilled in the art, or the dimensional difference of the rectangular through-hole 3 can be set to the same value as the dimensional difference between the separator and the negative electrode.
[0027] In some embodiments, the multiple separators are independent of each other, or the multiple separators are connected sequentially. In the battery cell, the separators can be stacked with the positive and negative electrode plates in a single sheet form, and the stacking is done one sheet at a time, or multiple separators can be connected together, and the stacking is done in a Z-shaped fold.
[0028] In some embodiments, when the positive electrode and the negative electrode are stacked, the positive electrode tab 1 and the negative electrode tab 2 are spaced apart at the top of the cell.
[0029] Example 1
[0030] The coated and rolled negative electrode sheet is cut into rectangular electrode sheets with a length L of 236 mm and a width W of 200 mm. The top of the rectangular electrode sheet has a negative electrode lug 2. A rectangular through hole 3 with a length L of 36 mm and a width W of 16 mm is punched in the center of the rectangular electrode sheet. In the width W direction, the distance D from the two sides of the rectangular through hole 3 to the two sides of the rectangular electrode sheet is 92 mm. In the length L direction, the distance D from the two sides of the rectangular through hole 3 to the two sides of the rectangular electrode sheet is 100 mm.
[0031] The positive electrode sheet is cut using the same method. The rectangular length L of the positive electrode sheet is 232 mm and the width W is 196 mm. The length L of the rectangular through hole 3 is 40 mm and the width W is 20 mm. In the width W direction, the distance D from the two sides of the rectangular through hole 3 to the edge of the rectangular electrode sheet is 88 mm. In the length L direction, the distance D from the two sides of the rectangular through hole 3 to the edge of the rectangular electrode sheet is 96 mm.
[0032] A single-piece diaphragm is cut, with a rectangular length L of 240 mm and a width W of 204 mm. The rectangular through-hole 3 has a length L of 32 mm and a width W of 12 mm. In the width W direction, the distance D from both sides of the rectangular through-hole 3 to the edge of the rectangular electrode is 96 mm. In the length L direction, the distance D from both sides of the rectangular through-hole 3 to the edge of the rectangular electrode is 104 mm.
[0033] The aforementioned positive electrode, negative electrode, and separator are stacked to form a battery cell, which is then assembled into a pouch battery. It should be noted that this disclosure does not specifically limit the preparation method of the pouch battery; those skilled in the art can perform electrode coating, rolling, cutting, stacking, welding, encapsulation, baking, electrolyte injection, and formation using well-known methods. During encapsulation, the aluminum-plastic film can be perforated according to the shape of the battery cell with rectangular through-holes to form an aluminum-plastic film shell with corresponding rectangular through-hole cavities. The battery cell is then installed into the aluminum-plastic film shell 4 for encapsulation. The first encapsulation includes a top seal, side seal, and bottom seal on the outside of the core package, while the second encapsulation involves sealing the rectangular through-hole 3 structure of the core package.
[0034] Example 2
[0035] The soft-pack battery was obtained using the same method as in Example 1, except that the rectangular through hole 3 in the negative electrode was not located at the center of the rectangular electrode. In the length L direction, the distances D from the two sides of the rectangular through hole 3 to the edge of the rectangular electrode were 150 mm and 50 mm, respectively.
[0036] In the positive electrode, the rectangular through hole 3 is not located at the center of the rectangular electrode. In the length L direction, the distances D from the two sides of the rectangular through hole 3 to the edge of the rectangular electrode are 146mm and 46mm, respectively.
[0037] In the diaphragm, the rectangular through hole 3 is not located at the center of the rectangular electrode. In the length L direction, the distances D from the two sides of the rectangular through hole 3 to the edge of the rectangular electrode are 154 mm and 54 mm, respectively.
[0038] Example 3
[0039] The soft-pack battery was obtained using the same method as in Example 1, except that the rectangular through hole 3 in the negative electrode was not located at the center of the rectangular electrode. In the width W direction, the distances D from the two sides of the rectangular through hole 3 to the edge of the rectangular electrode were 74 mm and 110 mm, respectively.
[0040] In the positive electrode, the rectangular through hole 3 is not located at the center of the rectangular electrode. In the width W direction, the distances D from the two sides of the rectangular through hole 3 to the edge of the rectangular electrode are 70mm and 106mm, respectively.
[0041] In the diaphragm, the rectangular through hole 3 is not located at the center of the rectangular electrode. In the width W direction, the distances D from the two sides of the rectangular through hole 3 to the edge of the rectangular electrode are 78 mm and 114 mm, respectively.
[0042] Comparative Example 1
[0043] The soft-pack battery was obtained using the same method as in Example 1, except that no rectangular through holes were provided on the negative electrode, positive electrode, and separator.
[0044] After the soft-pack batteries provided in Examples 1-3 and Comparative Example 1 were capacity-graded and then fully charged at 2C, they were disassembled and subjected to 200 cycles of 1.5C / 1.5C fast charging. The test results are shown in Table 1.
[0045] Table 1: Comparison of Test Results
[0046]
[0047]
[0048] As shown in Table 1, the energy density of the battery in Example 1 is 253 Wh / kg, which is only 2 Wh / kg lower than that of Comparative Example 1. After the cells of Example 1 were produced, they were fully charged and disassembled to examine the electrolyte wetting. Accelerated degradation of the interface was compared using a high-rate method to assess the uniformity of the fully charged interface. Disassembly of the 2C fully charged cells revealed that the cell interface of the battery provided in Example 1 was a uniform golden yellow, with uniform lithium intercalation during charging, indicating good electrolyte wetting. In contrast, the 2C interface of the cell provided in Comparative Example 1 was only golden yellow around the edges, with a noticeable dark area in the center. The entire interface was uneven, with a color difference between the center and the edges. Therefore, Comparative Example 1 showed good wetting only around the edges, with poor electrolyte wetting in the center. Further 2C / 2C cycling tests were conducted on the two cell types. After 200 cycles, the cells were fully charged and disassembled. It was found that the cell interface in Example 1 remained golden yellow, with good electrolyte wetting and a uniform interface. In contrast, the cell interface in Comparative Example 1 only showed a golden yellow color around the edges, with a noticeable white lithium plating area appearing in the center, covering more than 50% of the entire electrode, indicating performance degradation. Compared to Example 1, after 200 cycles of fast-charging cycling tests, Examples 2 and 3 also showed white lithium plating areas in the center of the 150mm long negative electrode section in Example 2 and the 110mm wide negative electrode section in Example 3, indicating performance degradation as well. This demonstrates that incorporating interconnected rectangular through-holes 3 in the positive electrode, negative electrode, separator, and aluminum-plastic film of the battery pack effectively improves electrolyte wetting, thereby enhancing fast-charging and cycle performance. Furthermore, positioning the rectangular through-holes 3 at the geometric center results in better current uniformity during charging and discharging, leading to improved battery interface properties.
[0049] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.
[0050] Furthermore, in the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0051] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0052] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0053] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.
Claims
1. An irregularly shaped electrode sheet, characterized in that: The device includes a positive electrode and a negative electrode, both of which are rectangular. The width of the negative electrode is greater than or equal to 150 mm and less than or equal to 340 mm, and the ratio of the width to the length of the rectangle is greater than or equal to 0.
8. The positive electrode has a positive tab at its top, and the negative electrode has a negative tab at its top. Both the positive and negative electrodes have rectangular through holes, and the four sides of the rectangular through holes are parallel to the four sides of the rectangular electrode. The maximum distance between the four sides of the rectangular through holes and the four sides of the rectangular electrode parallel to them is less than or equal to 100 mm.
2. The irregularly shaped electrode sheet according to claim 1, characterized in that: The center point of the rectangular through hole coincides with the center point of the rectangular electrode sheet.
3. The irregularly shaped electrode sheet according to claim 1, characterized in that: The rectangular electrode area of the positive electrode is smaller than that of the rectangular electrode area of the negative electrode.
4. The irregularly shaped electrode sheet according to claim 3, characterized in that: The area of the rectangular through hole on the positive electrode is greater than the area of the rectangular through hole on the negative electrode.
5. The irregularly shaped electrode sheet according to claim 1, characterized in that: The edge of the rectangular through hole in the width direction is parallel to the edge of the rectangular electrode in the width direction.
6. An irregularly shaped battery, characterized in that: The device includes a housing, and a battery cell is disposed inside the housing. The battery cell includes multiple overlapping separators and multiple positive and negative electrode plates as described in any one of claims 1-5. The separators are stacked between the positive and negative electrode plates. The separators are rectangular separators and have rectangular through holes. The shape of the housing matches the shape of the battery cell.
7. The irregularly shaped battery according to claim 6, characterized in that: The area of the separator is larger than the area of the rectangular electrode of the negative electrode, and the area of the rectangular through hole on the separator is smaller than the area of the rectangular through hole on the negative electrode.
8. The irregularly shaped battery according to claim 6, characterized in that: The multiple diaphragms are independent of each other, or the multiple diaphragms are connected in sequence.
9. The irregularly shaped battery according to claim 6, characterized in that: When the positive and negative electrode plates are stacked, the positive and negative electrode tabs are spaced apart at the top of the cell.