Battery cell, battery and battery module
By optimizing the diaphragm coating and electrode structure, and increasing the electrolyte capacity, the problem of lithium plating during the cycling process of pouch cells was solved, ensuring the normal performance and service life of the cells.
Patent Information
- Application Number
- CN202423152063.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-12-19
- Estimated Expiration
- 2034-12-20
AI Technical Summary
In existing soft-pack cells, lithium ion deintercalation and intercalation during lithium-ion battery cycling cause the electrode sheets to expand and contract, and the electrolyte to be squeezed out, leading to lithium deposition in the later stages of cycling, resulting in capacity loss and swelling, which affects cell performance.
The design incorporates a separator coating that is thicker in the middle and thinner on both sides along its width, and a positive and negative electrode material layer that is thinner in the middle and thicker on both sides. Grooves are provided to match the isolation section, and protrusions are provided at the corners of the electrodes to increase the electrolyte capacity and prevent lithium plating.
By increasing the electrolyte capacity, lithium plating in the cell can be avoided, ensuring the cell's flatness and normal performance, and extending the battery's lifespan.
Smart Images
Figure CN223693304U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to battery technology field especially relates to a kind of battery cell, battery and battery module. BACKGROUND
[0002] With the continuous development of lithium battery technology, the requirement of lithium ion (energy density, cycle life) is also higher and higher. However, due to the poor infiltration of the middle pole piece in the existing soft package battery cell (winding), as the lithium ion battery is cycled, the lithium ion is deintercalated and intercalated in the positive and negative electrodes, and the thickness of the positive and negative pole pieces also expands and shrinks accordingly. The gap between the large surface electrodes of the battery cell will continuously decrease, causing the electrolyte to be continuously squeezed out, resulting in lithium precipitation at the large surface of the battery cell in the later cycle due to the low electrolyte content, and further causing thickness abnormalities in the later cycle of the battery cell, thereby causing capacity loss and swelling and other defects of the battery cell, affecting the normal performance of the battery cell. SUMMARY
[0003] To solve the above technical problems, the utility model provides a kind of battery cell, battery and battery module, guarantee the electrolyte content of battery cell in later cycle, avoid the lithium precipitation of battery cell in later cycle, guarantee the normal performance of battery cell.
[0004] The technical solution adopted by the utility model to solve its technical problems is:
[0005] A battery cell is wound by a positive pole piece, a negative pole piece and a separator disposed between the positive pole piece and the negative pole piece.
[0006] The separator includes a base film and a coating layer coated on the surface of the base film. Along the width direction of the separator, the middle of the coating layer is thick and the two sides are thin.
[0007] The positive pole piece and the negative pole piece each include a foil and a material layer coated on both surfaces of the foil. Along the width direction of the foil, the middle of the material layer is thin and the two sides are thick.
[0008] Preferably, the coating layer includes a connecting part with the same thickness and an isolation part with different thicknesses along its width direction, and the other side of the connecting part is connected to the base film.
[0009] A groove is formed on the material layer, and the groove matches the isolation part.
[0010] Preferably, the sum of the maximum thicknesses of the two isolation parts is T1, and the sum of the thicknesses of the connecting parts on both surfaces of the base film is T2, and they satisfy:
[0011] (T1+T2) / T2=(1.1~10);
[0012] Wherein, 0um < T1 < 20um, 0um < T2 < 20um.
[0013] Preferably, the cross section of the isolation part is trapezoidal, the long base of the trapezoid is connected with the connecting part, and the length of the short base of the trapezoid is L1, the length of the long base of the trapezoid is L2, and L1 = (0.1-0.9) L2.
[0014] Preferably, the width of the negative electrode tab is A, the width of the positive electrode tab is B, and A-B = 1-4mm.
[0015] A-B = 1-4mm, and the value range of A is 20-200mm.
[0016] Preferably, the width of the diaphragm is C, and C-A = 1-4mm.
[0017] Preferably, it comprises a horizontal part and a corner part, and the positive electrode tab or the negative electrode tab is provided with a protrusion on the surface of the area of the corner part.
[0018] Preferably, the height of the protrusion is h, and h is 10-200um.
[0019] The end face of one end of the protrusion connected with the positive electrode tab or the negative electrode tab is circular, and the radius R of the end face is 5-500um.
[0020] A battery comprising the above-mentioned battery cell.
[0021] A battery module comprising the above-mentioned battery.
[0022] Compared with the prior art, the combination current collector plate, the battery and the battery module have the beneficial effects that: the coating layer of the diaphragm is arranged to be thick in the middle and thin on both sides along the width direction, thereby increasing the surface area of the coating layer, so that the diaphragm can accommodate more electrolyte, ensuring to provide free electrolyte in the later circulation stage, thereby avoiding lithium precipitation in the middle of the large surface of the battery cell, and further avoiding defects such as large capacity loss and swelling and warping of the battery cell due to insufficient residual electrolyte in the middle of the tab in the later circulation stage, and ensuring the normal performance of the battery cell.
[0023] In addition, the material layer of the positive electrode tab and the negative electrode tab is arranged to be thick in the middle and thin on both sides, so as to match the coating layer of the diaphragm, thereby avoiding unevenness of the battery cell caused by uneven thickness of the diaphragm, and ensuring the flatness of the battery cell. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1 It is a structural schematic view of the battery cell of the utility model.
[0025] Figure 2This is a schematic diagram of the diaphragm structure of this utility model.
[0026] Figure 3 This is a schematic diagram of the structure of the positive electrode sheet of this utility model.
[0027] Figure 4 This is a schematic diagram of the negative electrode sheet of this utility model.
[0028] Figure 5 This is an unfolded diagram of the positive electrode sheet of this utility model.
[0029] Figure 6 This is a side view of the unfolded positive electrode sheet of this utility model.
[0030] Wherein: 1-positive electrode sheet, 11-protrusion, 2-negative electrode sheet, 3-separator, 31-base film, 32-coating layer, 321-connecting part, 322-isolation part, 10-foil, 20-material layer, 201-groove, 100-cell, 101-horizontal part, 102-corner part. Detailed Implementation
[0031] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0032] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit its scope.
[0033] In this application, the appendix Figure 2 The D direction is the width direction of diaphragm 3, and the E direction is the thickness direction of diaphragm 3; with attachment Figure 3 The F direction is the width direction of the positive electrode plate 1, and the G direction is the thickness direction of the positive electrode plate 1; with attachment Figure 4 The H direction is the width direction of the negative electrode 2, and the I direction is the thickness direction of the negative electrode 2.
[0034] like Figures 1-4As shown, the positive electrode sheet 1, the negative electrode sheet 2 and the separator 3 are wound to form the electric core 100, so that the electric core 100 can form the horizontal part 101 (large surface) and the corner part 102. The separator 3 is used to prevent the positive electrode sheet 1 and the negative electrode sheet 2 from directly contacting, and can allow specific ions to pass, so as to achieve better battery performance and higher safety performance. Therefore, the width of the separator 3 is usually 2 wider than that of the negative electrode sheet. At the same time, in order to adapt to the working principle of the lithium ion battery and avoid the lithium precipitation phenomenon during charging, the width of the negative electrode sheet 2 needs to be designed to be greater than that of the positive electrode sheet 1. Specifically, if the width of the negative electrode sheet 2 is A, the width of the positive electrode sheet 1 is B, and the width of the separator 3 is C, the following relationship is satisfied:
[0035] A-B=1-4mm, such as 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, etc.
[0036] C-A=1-4mm, such as 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, etc. The value range of A is 20-200mm, such as 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 91mm, 92mm, 93mm, 94mm, 95mm, 96mm, 97mm, 98mm, 99mm, 100mm, 110mm, 120mm, 130mm, 140mm, 180mm, etc. One specific embodiment: A is 96mm, B is 94mm, and C is 98mm.
[0037] In the present application, the separator 3 includes a base film 31 and a coating layer 32 coated on both surfaces of the base film 31. Along the width direction of the separator 3, the middle part of the coating layer 32 is thick and the two sides are thin. The positive electrode sheet 1 and the negative electrode sheet 2 each include a foil 10 and a material layer 20 coated on both surfaces of the foil 10. Along the width direction of the foil 10, the middle part of the material layer 20 is thin and the two sides are thick, thereby forming a groove 201. The shape of the groove can be completely matched with the coating layer, or can be approximately matched.
[0038] Based on the above technical features, by setting the coating layer 32 of the separator 3 to be thick in the middle and thin on both sides along the width direction, the surface area of the coating layer 32 is increased, so that the separator 3 can accommodate more electrolyte, ensuring to provide free electrolyte in the later cycle, thereby avoiding lithium precipitation in the middle of the large surface of the electric core, and further avoiding the defects of large capacity loss and swelling and lifting caused by insufficient residual electrolyte in the middle of the electrode sheet in the later cycle of the electric core 100, and ensuring the normal performance of the electric core 100.
[0039] In addition, by setting the thickness of the material layer 20 of the positive electrode sheet 1 and the negative electrode sheet 2 to be thin in the middle and thick on both sides, the coated layer 32 of the separator 3 can be matched, and unevenness of the battery cell 100 caused by uneven thickness of the separator 3 can be avoided, thereby ensuring the flatness of the battery cell 100.
[0040] Please refer to the accompanying drawings Figure 2 In the embodiment, the coated layer 32 includes a connecting portion 321 with the same thickness and an isolation portion 322 with different thicknesses along the width direction thereof, the other side of the connecting portion 321 is connected to the base film 31, and the groove 201 is matched with the isolation portion 322. The cross section of the isolation portion 322 can be arc-shaped or trapezoidal, and the following description is based on the case that the cross section of the isolation portion 322 is trapezoidal.
[0041] In the application, the trapezoid formed by the cross section of the isolation portion 322 can be isosceles trapezoid or non-isosceles trapezoid, and preferably isosceles trapezoid, the long bottom side of which is connected to the connecting portion 321 and has the same width. If the length of the short bottom side of the trapezoid is L1, and the length of the long bottom side of the trapezoid is L2, L1=(0.1-0.9)L2, such as 0.2L2, 0.3L2, 0.4L2, 0.5L2, 0.6L2, 0.7L2, 0.8L2, etc.
[0042] Meanwhile, if the sum of the maximum thicknesses of the two isolation portions 322 is T1, and the sum of the thicknesses of the connecting portions 321 of the base film 31 and the two surfaces of the base film 31 is T2, the following condition is met therebetween:
[0043] (T1+T2) / T2=(1.1-10), such as (T1+T2) / T2=2, 3, 4, 5, 6, 7, 8, 9, etc. Meanwhile, 0um
[0044] Please refer to the accompanying drawings Figure 3 , 4Since the groove 201 matches the isolation part 322, that is, the cross section of the groove 201 is also trapezoidal, and the depth is H, H is T1 / 2. At the same time, the thickness of the positive electrode sheet 1 is 0-300um, such as 10um, 20um, 50um, 80um, 100um, 110um, 120um, 150um, 180um, 200um, 210um, 220um, 250um, 280um, etc. The thickness of the negative electrode sheet 2 is 0-300um, such as 10um, 20um, 50um, 80um, 100um, 110um, 120um, 150um, 180um, 200um, 210um, 220um, 250um, 280um, etc.
[0045] In addition, in the process of continuous expansion and shrinkage of the positive and negative electrode sheets, in addition to the lithium precipitation at the large surface of the battery cell 100 due to the small amount of electrolyte, the spacing between the positive and negative electrode sheets at the corner of the battery cell 100 will also decrease, resulting in abnormal thickness and affecting the performance of the battery cell 100. Therefore, the problem of lithium precipitation at the corner of the battery cell 100 needs to be further solved.
[0046] Please refer to the attached Figure 1 、 5 , 6, in this application, the surface of the area of the corner part 102 of the positive electrode sheet 1 or the negative electrode sheet 2 is provided with a protrusion 11, so that when the bare battery cell is wound, there is a certain gap between the positive and negative electrode sheets and the diaphragm 3 at the corner, which can accommodate more electrolyte, and can provide free electrolyte in the later cycle, thereby avoiding lithium precipitation at the corner. The protrusion 11 can be provided in multiple groups, and each group of the protrusion 11 includes a plurality of protrusion units uniformly distributed along the width direction of the positive electrode sheet 1 or the negative electrode sheet 2, so as to ensure the setting effect of the protrusion 11.
[0047] In the embodiment, the height of the protrusion 11 is h, and h is 10-200 um, such as 20 um, 30 um, 40 um, 50 um, 60 um, 70 um, 80 um, 90 um, 100 um, 110 um, 120 um, 130 um, 140 um, 150 um, 160 um, 170 um, 180 um, 190 um, etc. The end surface of the end of the protrusion 11 connected to the positive electrode tab 1 or the negative electrode tab 2 is circular, and the radius R of the end surface is 5-500 um, such as 10 um, 50 um, 100 um, 150 um, 200 um, 250 um, 300 um, 350 um, 400 um, 450 um, etc. The protrusion 11 is made by embossing process, that is, one surface of the tab is formed with the protrusion 11, and the other surface is recessed towards the protrusion 11 and formed with a circular hole, and the radius of the circular hole is also R.
[0048] In some embodiments, the protrusion 11 can be arranged on the positive electrode tab 1 or the negative electrode tab 2, or arranged on both, but in the actual production, since the foil material of the negative electrode tab 2 is copper foil, the hardness is relatively large, and the protrusion 11 is made by embossing process, and cracks may occur when the copper foil is embossed. The foil material of the positive electrode tab 1 is generally aluminum foil, and the hardness is relatively low, so the protrusion 11 is generally arranged on the positive electrode tab 1.
[0049] To solve the above technical problems, the application further provides a battery module comprising a battery, and the battery comprises the battery cell 100 described above. The battery module can effectively ensure the electrolyte content of the battery cell 100 in the later stage of the cycle, avoid lithium precipitation of the battery cell 100 in the later stage of the cycle, ensure the normal performance of the battery cell 100, and thus ensure the normal performance of the battery module.
[0050] The above description is only preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and replacements can be made, and these improvements and replacements should also be considered as the protection scope of the present application.
Claims
1. An electric cell, characterized by: It is wound by positive electrode sheet, negative electrode sheet and separator arranged between the positive electrode sheet and the negative electrode sheet; The separator includes a base film and a coating layer coated on the surface of the base film, and the coating layer is thicker in the middle and thinner on both sides along the width direction of the separator; The positive electrode sheet and the negative electrode sheet each include a foil and a material layer coated on both surfaces of the foil, and the material layer is thinner in the middle and thicker on both sides along the width direction of the foil.
2. The cell of claim 1, wherein: The coating layer includes a connecting part with the same thickness and an isolation part with different thicknesses along the width direction, and the other side of the connecting part is connected to the base film; The material layer is formed with a groove, and the groove matches the isolation part.
3. The cell of claim 2, wherein: The sum of the maximum thicknesses of the two isolation parts is T1, and the sum of the thicknesses of the connecting parts on both surfaces of the base film is T2, and they satisfy: (T1+T2) / T2=(1.1-10); Wherein, 0um 4. The cell of claim 2, wherein: The cross section of the isolation part is trapezoidal, the long base of the trapezoid is connected to the connecting part, and the length of the short base of the trapezoid is L1, and the length of the long base of the trapezoid is L2, L1=(0.1-0.9)L2.
5. The cell of claim 1, wherein: The width of the negative electrode sheet is A, and the width of the positive electrode sheet is B, and they satisfy: A-B=1-4mm, and the value range of A is 20-200mm.
6. The cell of claim 5, wherein: The width of the separator is C, and C-A=1-4mm.
7. The cell of any one of claims 1-6, wherein: It includes a horizontal part and a corner part, and the surface of the area of the corner part where the positive electrode sheet or the negative electrode sheet is located is provided with a protrusion.
8. The cell of claim 7, wherein: The height of the protrusion is h, h is 10-200um; The end face of one end of the protrusion connected to the positive electrode sheet or the negative electrode sheet is circular, and the radius R of the end face is 5-500um.
9. A battery, characterized by: It includes the battery cell as claimed in any one of claims 1-8.
10. A battery module, characterized by It includes the battery as claimed in claim 9.