Battery cell and battery module

Abstract

The utility model relates to the technical field of batteries, particularly provides a battery monomer, and aims to solve the technical problem that lithium is separated out due to gaps generated between pole pieces caused by different diameters of two ends of a battery cell and other parts of the battery cell. Therefore, the battery monomer provided by the utility model comprises a shell, the electrode assembly is arranged in the shell; the collector plate assembly is provided with an insulating part, the insulating part comprises a blocking part, and the blocking part is arranged between the electrode assembly and the shell; the thicknesses of the blocking parts are different in the first direction. By arranging the insulating part on the collector plate assembly, the contact between the battery cell and the inner wall of the shell can be avoided, so that the battery cycle diving is prevented, and the serious influence on the performance is prevented; and meanwhile, the extension lengths of the blocking parts are different, so that places with different diameters of the battery cells can be made up, the diameters of the battery cells are kept consistent, and negative effects caused by loose lithium precipitation of the pole pieces due to different diameters of the battery cells are avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and specifically provides a battery monomer and a battery module. Background Art

[0002] Lithium-ion batteries have outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide adaptability, and small self-discharge coefficient. They are one of the most widely used batteries in the world today and an important part of the development of new energy.

[0003] With the continuous upgrading of market demand, cylindrical batteries have developed from 18650 and 21700 to the larger and more energy-dense 4680 series cylindrical batteries. Compared with 18650 and 21700 cylindrical cells, the 4680 cylindrical battery adopts a full-ear design, which effectively shortens the current path, promotes smoother movement of electrons inside the battery, reduces the internal resistance of the cell itself, and significantly reduces Joule heat loss. In addition, cylindrical batteries are made of stainless steel, have higher mechanical strength, and can effectively absorb the pressure caused by the expansion of the negative electrode, so they are more suitable for high-silicon and high-nickel systems.

[0004] However, there is a potential problem in the design of cylindrical batteries. Since the diameters of the two ends of the battery cell are different from those of the rest of the battery cell, there is excess space between the battery cell and the shell during the expansion of the battery cell. After the battery cell circulates and breathes, the pole pieces become loose and gaps form between the pole pieces, leading to lithium deposition. Lithium deposition not only reduces battery performance and significantly shortens cycle life, but also limits the fast charging capacity of the battery and may cause catastrophic consequences such as combustion and explosion. Utility Model Content

[0005] The utility model aims to solve the above technical problem, that is, to solve the technical problem that a gap is generated between pole pieces due to the different diameters between the two ends of a battery cell and other parts of the battery cell, thereby causing lithium deposition.

[0006] In a first aspect, the utility model provides a battery cell, comprising: a shell; an electrode assembly, the electrode assembly is arranged in the shell; a collecting plate assembly, the collecting plate assembly has an insulating member, the insulating member includes a blocking portion, the blocking portion is arranged between the electrode assembly and the shell; along a first direction, the thickness of the blocking portion is different.

[0007] In the above technical solution, an insulating member is provided on the collecting disc assembly, and the insulating member at least partially forms a blocking portion, which is provided between the electrode assembly and the shell. Due to the provision of the insulating member, after the battery cell tilts or expands during long-term operation, the insulating member can prevent the battery cell from contacting the inner wall of the shell, thereby preventing the battery cycle from diving and seriously affecting the performance; at the same time, along the first direction, the thickness of the blocking portion (the extension length in the second direction) is different, which can compensate for the different diameters of the battery cell, so that the diameter of the battery cell remains consistent in the first direction, thereby preventing the different diameters of the battery cell from causing loose lithium deposition on the electrode sheet and producing adverse consequences.

[0008] In some embodiments, along the first direction, the thickness of the barrier portion gradually increases.

[0009] In the above technical solution, since the diameter of the battery cell tends to increase from both ends to the middle in the first direction, the thickness of the blocking portion (the extension length in the second direction) is set to gradually increase, which can adapt well to and compensate for the change in the diameter of the battery cell, thereby ensuring that the diameter of the battery cell remains consistent in the first direction and avoiding loose lithium deposition on the electrode due to different battery cell diameters, which may lead to adverse consequences.

[0010] In some embodiments, the electrode assembly includes a pole piece, the pole piece includes a coating area and a pole ear, the coating area has a base area and a thinning area, the thinning area is close to the end of the pole ear, and the thickness of the thinning area is less than the thickness of the base area.

[0011] In the above technical solution, a thinning area is provided on the pole piece to improve the energy density. By thinning the pole piece, the specific surface area of ​​the pole piece can be increased, the energy storage capacity of the battery can be improved, and the power characteristics of the battery can be improved. The thinned pole piece can provide a shorter ion and electron transmission path, accelerate the reaction speed, and improve the output power of the battery.

[0012] In some embodiments, in the first direction, the barrier portion covers the tab and at least a portion of the thinned region.

[0013] In the above technical solution, the blocking portion covers the pole ear and at least a portion of the thinned area, preventing the active material in the pole piece coating area from connecting with the shell, thereby playing an effective insulating role.

[0014] In some embodiments, in the first direction, a length of the blocking portion is less than or equal to a length of the thinned region.

[0015] In the above technical solution, due to the existence of the thinning area of ​​the pole piece, the diameters of the two ends of the battery cell and the middle of the battery cell are different. In order to ensure the consistency of the diameter of the battery cell, a blocking part is set on the insulating part to make up for the diameter difference caused by the thinning area. If the length of the blocking part is set to exceed the length of the thinning area, the battery cell will be squeezed and uneven force will be applied to the battery cell. Therefore, setting the length of the blocking part to be less than or equal to the thinning area can avoid the above problem.

[0016] In some embodiments, the length of the blocking portion in the first direction is greater than or equal to 0.5 mm and less than or equal to 5 mm; and / or the thickness of the blocking portion in the first direction is greater than or equal to 0.1 mm and less than or equal to 0.5 mm.

[0017] In the above technical solution, by setting the length of the blocking part in the first direction to be greater than or equal to 0.5 mm and less than or equal to 5 mm, it is prevented that the electrode assembly and the shell cannot be effectively insulated due to the blocking part being set too small, and the blocking part being set too large, resulting in stress concentration when the pole piece expands; at the same time, the thickness of the blocking part in the first direction is set to be greater than or equal to 0.1 mm and less than or equal to 0.5 mm, because setting the thickness of the blocking part too thin will cause difficulties in manufacturing, and setting it too thick will also cause stress concentration when the pole piece expands and thus lead to lithium deposition.

[0018] In some embodiments, the current collecting plate assembly includes a current collecting plate body, and the insulating member is annular and is disposed around the outer circumference of the current collecting plate body.

[0019] In the above technical solution, by surrounding the insulating part on the outer peripheral side of the current collecting plate body to separate the battery cell and the shell, after the battery cell tilts or expands after working for a long time, the insulating part can prevent the battery cell from contacting the inner wall of the shell, thereby preventing the battery from diving during circulation and seriously affecting the performance. In addition, the insulating part can also play a role in positioning the current collecting plate and the battery cell during the assembly process of the battery, so that the battery cell is centered and prevented from being eccentric. Therefore, after the battery adopts the current collecting plate assembly, the reliability is further improved.

[0020] In some embodiments, the insulating member further includes a connecting portion, which is annular and connected to the periphery of the collecting plate body, and the blocking portion is connected to the connecting portion.

[0021] In some embodiments, the angle between the connecting portion and the blocking portion is greater than or equal to 160 degrees and less than or equal to 180 degrees.

[0022] In the above technical solution, the angle between the connecting part and the blocking part is set to be less than or equal to 180 degrees to ensure that the insulating part is not flush with the shell entry guide surface to prevent interference with the film when the core is assembled with the shell; it is set to be greater than or equal to 160 degrees to prevent the blocking part from shrinking and resetting after the core is entered into the shell.

[0023] In some embodiments, the blocking portion is further provided with a plurality of stress grooves, and the plurality of stress grooves are evenly distributed along the circumference of the blocking portion.

[0024] In the above technical solution, by providing a plurality of stress grooves on the blocking part, it is possible to avoid excessive stress and severe deformation of the blocking part when it shrinks when the blocking part and the battery cell are assembled; the plurality of stress grooves are evenly distributed along the circumference, so that the collecting plate assembly can be evenly stressed without deflection.

[0025] In a second aspect, the utility model further provides a battery module, wherein the battery module comprises a plurality of the above-mentioned battery cells.

[0026] The advantages of the battery module and the above-mentioned battery cell over the prior art are the same, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 It is a partial cross-sectional view of a battery cell provided by an embodiment of the utility model;

[0029] Figure 2 It is a structural schematic diagram of a current collecting plate assembly provided by an embodiment of the utility model;

[0030] Figure 3 It is a cross-sectional view of an electrode provided in an embodiment of the utility model.

[0031] List of reference numerals:

[0032] 1. Shell; 2. Electrode assembly; 21. Pole piece; 211. Base area; 212. Thinning area; 213. Ear area; 214. Coating area; 3. Collector plate assembly; 31. Insulator; 311. Blocking part; 312. Connecting part; 32. Collector plate body; 4. Stress groove. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0034] It should be noted that in the description of the present invention, the terms "inside", "outside", "top", "bottom" and other terms indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", and "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0035] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "setting" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0037] In the prior art, in order to solve the insulation between the battery cell and the shell, a plastic part is sleeved on the outer peripheral side of the current collecting disk, and the plastic part is arranged between the battery cell and the shell. The inventor found that due to the different diameters of the two ends of the winding core and the middle winding core, gaps were found between the pole pieces after the battery cell cycle, resulting in excess space between the battery cell and the shell, looseness between the wound multi-layer pole pieces and gaps between the pole piece layers. The existence of the gap will cause lithium deposition on the pole piece, which not only reduces the performance of the battery and greatly shortens the cycle life, but also limits the fast charging capacity of the battery, and may cause catastrophic consequences such as combustion and explosion. At the same time, if the plastic part arranged between the battery cell and the shell is not optimized, it will not only fail to solve the problem of lithium deposition, but also produce local stress, which will further cause more serious lithium deposition. Based on this, the inventor provides a battery cell that can solve the above-mentioned technical problems. The specific embodiments of the battery cell of the utility model are described in detail below in conjunction with the accompanying drawings.

[0038] Please refer to Figures 1 to 3 , Figures 1 to 3 This is a schematic structural diagram of a battery cell, a current collecting plate assembly 3 and a pole piece 21 provided in an embodiment of the utility model.

[0039] In the present invention, the battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries or magnesium-ion batteries, etc., and the embodiments of the present invention are not limited to this. The battery cells may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present invention are not limited to this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present invention are not limited to this. The following takes a cylindrical battery cell as an example to describe the solution of this embodiment:

[0040] The cylindrical battery cell includes a shell 1; an electrode assembly 2, the electrode assembly 2 is arranged in the shell 1, and the electrode assembly 2 is composed of a positive electrode sheet 21, a negative electrode sheet 21 and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet 21 and the negative electrode sheet 21 to work. The material of the separator is not limited, for example, it can be polypropylene or polyethylene. The current collecting plate assembly 3 is generally arranged between the electrode assembly 2 and the shell 1 to introduce or lead out the current. The current collecting plate assembly 3 includes an insulating member 31 and a current collecting plate body 32. In this embodiment, the current collecting plate body 32 is formed into a disc-shaped structure, and the insulating member 31 is formed into a circular ring-shaped structure and is sleeved on the outer peripheral side of the current collecting plate body 32. At least a portion of the insulating member 31 forms a blocking portion 311, which is arranged between the electrode assembly 2 and the shell 1 and is used to prevent contact and conduction between the electrode assembly 2 and the shell 1. In the first direction (that is, Figure 2 In the X direction in FIG. 1 , the thickness of the blocking portion 311 is different, that is, the blocking portion 311 in the second direction (that is, Figure 2 The extension lengths of the blocking portion 311 in the Y direction in the prior art are different. Compared with the solution in which the blocking portion 311 is set to have the same extension length in the second direction, the utility model sets different extension lengths of the blocking portion 311, so that the radius of the battery cell remains consistent in the second direction. The different extension lengths include both different lengths of various parts and some being the same and some being different, which is not limited in the embodiments of the utility model; further, the radius of the battery cell usually tends to be small at both ends and large in the middle. In this embodiment, the extension length of the blocking portion 311 in the second direction gradually increases along the first direction, so as to better adapt to the change in the radius of the battery cell.

[0041] See also Figure 3, the electrode assembly 2 includes a pole piece 21. Taking the positive pole piece 21 as an example, the positive pole piece 21 of the utility model includes a positive current collector and a positive active material layer. The positive active material layer is directly or indirectly coated on the positive current collector. The positive current collector not coated with the positive active material layer protrudes from the positive current collector coated with the positive active material layer. The positive current collector not coated with the positive active material layer serves as a pole ear 213; the area coated with the positive active material layer is a coating area 214. The pole piece 21 is provided with a substrate area 211, a thinning area 212 and a pole ear 213. In the first direction, the blocking portion covers the pole ear 213 and at least part of the thinning area 212, and the thickness of the thinning area 212 in the second direction is less than the thickness of the substrate area 211 in the second direction. In this embodiment, in the first direction, the end of the blocking portion 311 covers the pole ear 213 and at least part of the thinning area 212, preventing the active material coating area 214 of the pole piece 21 from contacting the shell 1, and playing an insulating role. Furthermore, in the first direction, the length of the blocking portion 311 is less than or equal to the length of the thinning area 212. Due to the existence of the thinning area 212 of the pole piece 21, the radius of the area of ​​the battery cell in the first direction where the thinning area 212 is located is smaller than the radius of other areas of the battery cell. Setting the length of the blocking portion 311 to be less than or equal to the length of the thinning area 212 can avoid the blocking portion 311 being too long and squeezing the pole piece 21, resulting in stress concentration and lithium deposition. Furthermore, in this embodiment, the length of the blocking portion 311 is greater than or equal to 0.5 mm and less than or equal to 5 mm. Preferably, the length of the blocking portion 311 is set to 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm; the thickness of the blocking portion 311 is set to 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm. See. Figure 2 The insulating member 31 of this embodiment also includes a connecting portion 312, which is formed into a ring extending in the first direction and the second direction, and is sleeved on the outer circumference of the collector body 32. The blocking portion 311 is connected to the connecting portion 312, and the connecting portion 312 extends in the first direction. Preferably, the blocking portion 311 and the connecting portion 312 are integrally formed, and the overall structure of the insulating member 31 is simple and easy to assemble. In this embodiment, the angle between the blocking portion 311 and the connecting portion 312 is greater than or equal to 160 degrees and less than or equal to 180 degrees. Furthermore, the blocking portion 311 is also provided with a plurality of stress grooves 4 along the circumferential direction. When the insulating member 31 is sleeved on the collector body 32 and installed on the battery, the interaction between the blocking portion 311 and the shell 1 will cause a certain degree of deformation. In order to ensure the reliability of assembly, the setting of the stress groove 4 can effectively absorb the deformation stress during the process. Furthermore, the plurality of stress grooves 4 are evenly distributed along the circumference of the blocking portion 311 , so that the current collecting plate assembly 3 is evenly stressed in all directions, thereby ensuring the flatness of the current collecting plate body 32 .

[0042] The utility model also provides a battery module having a plurality of battery cells. The beneficial effects of the battery module are the same as the advantages of the battery cells in this embodiment over the prior art, and will not be described in detail here.

[0043] So far, the technical solution of the utility model has been described in conjunction with the preferred embodiments shown in the accompanying drawings, but it is easy for those skilled in the art to understand that the protection scope of the utility model is obviously not limited to these specific embodiments. Without departing from the principle of the utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the utility model.

Claims

1. A battery cell, characterized in that: include: case; an electrode assembly, wherein the electrode assembly is disposed in the housing; The collecting plate assembly comprises an insulating member, wherein the insulating member comprises a blocking portion, the blocking portion is arranged between the electrode assembly and the shell, and the thickness of the blocking portion is different along a first direction.

2. The battery cell according to claim 1, characterized in that: Along the first direction, the thickness of the blocking portion gradually increases.

3. The battery cell according to claim 2, characterized in that: The electrode assembly includes a pole piece, which includes a coating area and a pole ear. The coating area has a base area and a thinning area. The thinning area is close to the end of the pole ear, and the thickness of the thinning area is less than the thickness of the base area.

4. The battery cell according to claim 3, characterized in that: The blocking portion covers the tab and at least a portion of the thinned area.

5. The battery cell according to claim 4, characterized in that: In the first direction, the length of the blocking portion is less than or equal to the length of the thinned area.

6. The battery cell according to claim 1, characterized in that: The length of the blocking portion in the first direction is greater than or equal to 0.5 mm and less than or equal to 5 mm; and / or the thickness of the blocking portion in the first direction is greater than or equal to 0.1 mm and less than or equal to 0.5 mm.

7. The battery cell according to claim 1, characterized in that: The current collecting plate assembly comprises a current collecting plate body, and the insulating member is annular and is disposed around the outer circumference of the current collecting plate body.

8. The battery cell according to claim 7, characterized in that: The insulating member further includes a connecting portion, which is annular and connected to the periphery of the collecting plate body, and the blocking portion is connected to the connecting portion.

9. The battery cell according to claim 8, characterized in that: An included angle between the connecting portion and the blocking portion is greater than or equal to 160 degrees and less than or equal to 180 degrees.

10. The battery cell according to claim 8, characterized in that: The blocking portion is further provided with a plurality of stress grooves, and the plurality of stress grooves are evenly distributed along the circumference of the blocking portion.

11. A battery module, characterized in that: include: A plurality of battery cells as claimed in any one of claims 1 to 10.

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