Single cell and battery pack

Abstract

The application relates to the battery technical field and discloses a single battery and a battery pack. The winding core of the single battery has a radial direction. The winding core is formed by stacking and winding a first pole piece, a first diaphragm, a second pole piece and a second diaphragm; the winding core has multiple groups of through hole groups, each of which comprises multiple through holes; in the radial direction of the winding core, the through holes pass through the second pole piece, and the through holes in each through hole group are distributed on the adjacent multiple turns of the second pole piece, so that each turn of the second pole piece has multiple through holes, and in the radial direction, the adjacent two through holes in the through hole group are oppositely arranged; the second pole piece has a flattening direction in a flattened state, the positioning tolerance of the through holes is p mm; in the flattened state of the second pole piece and in the same turn of the second pole piece, the difference between the distances of any two adjacent through holes in the flattening direction is P mm, and 0<=P<=4p is satisfied. In the above manner, the application can improve the diffusion efficiency and exhaust efficiency of electrolyte.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a single cell and a battery pack. Background Technology

[0002] The full tab process of large cylindrical batteries involves cutting the positive and negative current collectors on both sides of the core into tabs, and then welding the current collectors to the current collector plate or battery casing. This significantly reduces the battery's internal resistance and heat generation, meeting the requirements for high energy density, fast charging, and high power performance.

[0003] Large cylindrical batteries typically use a central through-hole formed after the core is wound as the electrolyte injection channel, meaning the electrolyte is injected into the central through-hole. However, the efficiency of electrolyte diffusion along the radial direction of the core after injection into the central through-hole is low, resulting in low injection efficiency and wetting efficiency. Furthermore, after battery formation or aging, the gas generated at the electrodes in the middle ring of the core is difficult to expel quickly, increasing the risk of core polarization and lithium plating during long-cycle operation. Utility Model Content

[0004] This application provides a single-cell battery and a battery pack that can improve the diffusion efficiency and venting efficiency of the electrolyte.

[0005] This application provides a single-cell battery. The single-cell battery includes a housing. The single-cell battery also includes a core, which has a radial direction and is disposed in the housing. The core is formed by stacking and winding a first electrode, a first separator, a second electrode, and a second separator. The core has multiple sets of through-hole groups, each of which includes multiple through-holes. In the radial direction of the core, the through-holes penetrate the second electrode. Each through-hole in the through-hole group is distributed across multiple adjacent turns of the second electrode, such that each turn of the second electrode has multiple through-holes. In the radial direction, two adjacent through-holes in the through-hole group are positioned opposite each other. The second electrode has a flattening direction in its flattened state, and the positioning tolerance of the through-holes is p mm. In the flattened state of the second electrode and within the same turn of the second electrode, the difference in distance between any two adjacent through-holes in the flattening direction is P mm, satisfying: 0 ≤ P ≤ 4p.

[0006] In one embodiment of this application, when the second electrode is in a flattened state, the distance between two through holes belonging to the same through hole group on the nth and (n+1)th turns of the second electrode in the flattened direction is D. n mm, satisfying: D n+1 -D n =2π(a+b+2s), where the thickness of the first electrode is a mm, the thickness of the second electrode is b mm, the thickness of the first diaphragm is s mm, and the thickness of the second diaphragm is s mm.

[0007] In one embodiment of this application, the through holes in the through-hole group are sequentially numbered in the radial direction of the core, from the inside to the outside, and the total number of through holes in the through-hole group is N; one end of the second electrode is the winding end, and the second electrode is wound around the winding end; when the second electrode is in a flattened state, the distance between each through hole in the through-hole group and the winding end in the flattening direction is L. n mm, where n is 1, 2, 3…N, satisfying: L n = nL1+n(n-1)D / 2.

[0008] In one embodiment of this application, the second electrode includes a second coated portion, a second empty foil portion, and a second electrode tab distributed along the axial direction of the core, and the second empty foil portion has a through hole.

[0009] In one embodiment of this application, the diameter of the through hole is d mm, and the dimension of the second empty foil portion in the axial direction of the core is M mm, satisfying: p≤d≤M.

[0010] In one embodiment of this application, the positioning tolerance p mm of the through hole also satisfies: 0 < p ≤ 0.5.

[0011] In one embodiment of this application, the dimension M mm of the second empty foil portion in the axial direction of the core also satisfies: 0.5≤M≤10.

[0012] In one embodiment of this application, the first electrode includes a first coated portion, a first empty foil portion, and a first electrode tab distributed along the axial direction of the core. The first empty foil portion has a through hole. The second electrode includes a second coated portion, a second empty foil portion, and a second electrode tab distributed along the axial direction of the core. The second empty foil portion has a through hole. The first electrode tab is located at one end of the core along its axial direction, and the second electrode tab is located at the other end of the core along its axial direction. In the radial direction of the core, the end of the first coated portion away from the first empty foil portion is disposed opposite to the second coated portion, and the end of the second coated portion away from the second empty foil portion is disposed opposite to the first coated portion.

[0013] In one embodiment of this application, the center of the core has a central through hole that extends through it along its axial direction; in the radial direction of the core, each through hole in the through hole group is disposed opposite to the central through hole.

[0014] Accordingly, this application also provides a battery pack, including a housing and individual batteries as described in the above embodiments, wherein the individual batteries are disposed in the housing.

[0015] The beneficial effects of this application are as follows: Unlike existing technologies, this application provides a single-cell battery and a battery pack. The core of the single-cell battery has multiple sets of through-hole groups, each of which includes multiple through-holes. In the radial direction of the core, two adjacent through-holes in the through-hole groups are arranged opposite each other, that is, two adjacent through-holes in the through-hole groups are interconnected. In this way, the electrolyte can diffuse rapidly along the radial direction of the core through the multiple through-holes in the through-hole groups, which can improve the diffusion efficiency of the electrolyte, and is beneficial to improving the liquid injection efficiency and wetting efficiency. Furthermore, the gas inside the core can also be vented through the multiple through-holes in the through-hole groups, which can improve the venting efficiency, reduce the risk of lithium plating, and thus improve the performance of the single-cell battery.

[0016] Furthermore, in the radial direction of the core, each through-hole in the through-hole group is distributed across multiple adjacent turns of the second electrode sheet, resulting in multiple through-holes on each turn of the second electrode sheet. When the second electrode sheet is in a flattened state and within the same turn of the second electrode sheet, the difference in distance between any two adjacent through-holes in the flattened direction is P mm, satisfying: 0 ≤ P ≤ 4p. In other words, the multiple through-hole groups in the core of this application are approximately uniformly spaced in the circumferential direction of the core, which can improve the electrolyte diffusion efficiency and venting efficiency at different locations of the core, further improving the electrolyte injection efficiency and wetting efficiency, and reducing the risk of lithium plating. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of one embodiment of the core of this application;

[0019] Figure 2 yes Figure 1 A schematic diagram of the structure at the other end of the core is shown;

[0020] Figure 3 yes Figure 1 A partial schematic diagram of the cross-sectional structure of the core along the EE direction shown.

[0021] Figure 4 yes Figure 2 A partial schematic diagram of the cross-sectional structure of the core along the FF direction shown;

[0022] Figure 5 This is a schematic diagram of an embodiment of the first electrode sheet in a flattened state according to this application;

[0023] Figure 6This is a schematic diagram of an embodiment of the second electrode sheet in a flattened state according to this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "up," "down," "left," and "right" generally refer to up, down, left, and right in the actual use or working state of the device, specifically the drawing directions in the accompanying drawings.

[0025] In this application, unless otherwise expressly specified and limited, the terms "connected," "linked," "stacked," 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 direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0026] This application provides a single-cell battery and a battery pack, which are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0027] To address the technical problems of low electrolyte diffusion efficiency and venting efficiency in existing wound cores, an embodiment of this application provides a single-cell battery. The single-cell battery includes a casing. It also includes a wound core, which has a radial orientation and is disposed within the casing. The wound core is formed by stacking and winding a first electrode, a first separator, a second electrode, and a second separator. The wound core has multiple sets of through-hole groups, each including multiple through-holes. In the radial direction of the wound core, the through-holes penetrate the second electrode. Each through-hole in a through-hole group is distributed across adjacent turns of the second electrode, such that each turn of the second electrode has multiple through-holes. In the radial direction, adjacent through-holes in a through-hole group are positioned opposite each other. The second electrode has a flattening direction in its flattened state, and the positioning tolerance of the through-holes is p mm. In the flattened state of the second electrode and within the same turn of the second electrode, the difference in distance between any two adjacent through-holes in the flattening direction is P mm, satisfying: 0 ≤ P ≤ 4p. This will be described in detail below.

[0028] Please see Figures 1 to 4 , Figure 1 This is a schematic diagram of the structure of one embodiment of the core of this application. Figure 2 yes Figure 1 The diagram shows the structure of the other end of the core. Figure 3 yes Figure 1 A partial schematic diagram of the cross-sectional structure of the core along the EE direction. Figure 4 yes Figure 2 A partial schematic diagram of the cross-sectional structure of the core along the FF direction.

[0029] The axial direction Z, radial direction X, and circumferential direction C are mutually perpendicular. It should be noted that in all embodiments of this application, the axial direction Z refers to the direction indicated by the arrow in the accompanying drawings; it should be understood that reversing the positive or negative directions of one or more of the axial direction Z, radial direction X, and circumferential direction C will not substantially affect the single cell and battery pack provided in the embodiments of this application, nor will it lead to adverse results such as the inability to achieve the desired technical effect. It should be understood that the axial direction Z is the direction indicated by a straight line perpendicular to the plane of the outer surface of the casing. A cylindrical coordinate system is constructed with a straight line passing through the center of the plane of the outer surface of the shell and parallel to the axial direction Z as the axis (provided that the surface of the core 10 near the end cap should be a circle parallel to and coaxial with the outer surface of the end cap, and therefore can also be regarded as the axis of the core 10). The circumferential direction C refers to the direction of the tangent of the circle with the intersection of the aforementioned axis and the aforementioned plane as the center on the plane perpendicular to the axial direction Z. The radial direction X refers to the direction of the ray in the aforementioned plane starting from the intersection of the aforementioned axis and the aforementioned plane.

[0030] It should be understood that the concepts of axial direction Z, radial direction X, and circumferential direction C are introduced in all embodiments of this application merely for the convenience of describing spatial positional relationships and should not be construed as limiting the scope of the embodiments of this application. Therefore, the fact that axial direction Z, radial direction X, and circumferential direction C are mutually perpendicular can be reasonably interpreted, based on the actual technical scenario, as a nearly perpendicular directional relationship between each pair of axial direction Z, radial direction X, and circumferential direction C, for example, the included angle between each pair of axial direction Z, radial direction X, and circumferential direction C is in the range of 85°-95°... As long as the technical solution conforms to the spirit of this application or achieves the technical effect described in this application, it can be considered to fall within the scope defined by the appended claims. In the various embodiments of this application, the flattening direction T and the axis Z are introduced merely for the convenience of describing spatial positional relationships and should not be construed as limiting the scope of the embodiments of this application. Therefore, the pairwise perpendicular relationship between the flattening direction T and the axis Z can be interpreted, depending on the actual technical scenario, as the flattening direction T and the axis Z respectively representing three mutually perpendicular directions in three-dimensional space, or reasonably interpreted as a nearly perpendicular directional relationship between the flattening direction T and the axis Z, for example, the included angle between the flattening direction T and the axis Z is in the range of 85°-95°... As long as the technical solution can conform to the spirit of this application or achieve the technical effect described in this application, it can be considered to fall within the scope defined by the appended claims.

[0031] In one embodiment, the battery pack includes a housing and multiple individual battery cells disposed within the housing. Individual battery cells include, but are not limited to, lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and this disclosure does not limit the specific types. The battery pack provides power to an electrical device. The electrical device can be a mobile phone, portable device, laptop computer, electric vehicle, electric car, ship, spacecraft, electric toy, or power tool, etc. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.

[0032] Specifically, the single-cell battery includes a casing and a core 10, with the core 10 disposed within the casing. The core 10 is formed by stacking and winding electrode sheets 11 and separators 12, specifically by stacking and winding a first electrode sheet 111, a first separator 121, a second electrode sheet 112, and a second separator 122. The first electrode sheet 111 can be a positive electrode sheet, and the second electrode sheet 112 can be a negative electrode sheet, or the first electrode sheet 111 can be a negative electrode sheet, and the second electrode sheet 112 can be a positive electrode sheet. This application uses the example of the first electrode sheet 111 being a positive electrode sheet and the second electrode sheet 112 being a negative electrode sheet for illustrative purposes only and should not be construed as limiting the scope of protection of this application.

[0033] The core 10 of the present application embodiment will be described below.

[0034] Please refer to the following: Figure 5 and Figure 6 , Figure 5 This is a schematic diagram of an embodiment of the first electrode in a flattened state. Figure 6 This is a schematic diagram of an embodiment of the second electrode sheet in a flattened state according to this application.

[0035] In one embodiment, the winding core 10 has a radial direction X. The winding core 10 has multiple sets of through-hole groups 20, each through-hole group 20 including multiple through holes 21. Figure 2 As shown, Figure 2 The location of the through-holes 21 is shown. The through-holes 21 penetrate the second electrode 112 along the radial direction X of the core 10. Two adjacent through-holes 21 in the through-hole group 20 are positioned opposite each other, meaning they are interconnected. This allows the electrolyte to diffuse rapidly along the radial direction X of the core 10 through the multiple through-holes 21 in the through-hole group 20. This significantly improves the electrolyte diffusion efficiency, particularly for cylindrical batteries where the injection hole is directly opposite the central axis of the core 10, thus enhancing injection and wetting efficiency. Furthermore, gases inside the core 10 can be vented through the multiple through-holes 21 in the through-hole group 20, improving venting efficiency, reducing the risk of lithium plating, and ultimately improving the safety, production efficiency, and yield of individual cells.

[0036] Specifically, the core 10 has a central through hole 16 extending along its axial direction Z in its middle portion, which is used for injecting electrolyte. In the radial direction X of the core 10, each through hole 21 in the through hole group 20 is positioned opposite to the central through hole 16, meaning that each through hole 21 in the through hole group 20 is interconnected with the central through hole 16. Thus, the electrolyte injected into the central through hole 16 can rapidly diffuse along the radial direction X of the core 10 through the multiple through holes 21 in the through hole group 20, improving the electrolyte diffusion efficiency and thus enhancing the injection and wetting efficiency.

[0037] In one embodiment, such as Figure 6 As shown, in the radial direction X of the core 10, each through hole 21 in the through hole group 20 is distributed in adjacent multiple turns of the second electrode 112, such that each turn of the second electrode 112 has multiple through holes 21. The second electrode 112 has a flattening direction T in the flattened state, and the positioning tolerance of the through holes 21 is p mm. When the second electrode 112 is in the flattened state and in the same turn of the second electrode 112, the difference in distance between any two adjacent through holes 21 in the flattening direction T is P mm, satisfying: 0≤P≤4p. In other words, the multiple through hole groups 20 of the core 10 of this application are approximately uniformly spaced in the circumferential direction C of the core 10, which can improve the electrolyte diffusion efficiency and venting efficiency at different positions of the core 10, further improve the liquid injection efficiency and wetting efficiency, and help reduce the risk of lithium plating.

[0038] It should be noted that in this embodiment, when the second electrode 112 is in a flattened state and within the same coil of the second electrode 112, the theoretical difference in distance between any two adjacent through holes 21 in the flattening direction T is 0 mm. This ensures that the multiple sets of through holes 20 of the core 10 are distributed as evenly as possible along the circumferential direction C of the core 10. Since the through holes 21 have a positioning tolerance p mm, the difference in distance P mm between any two adjacent through holes 21 in the flattening direction T within the same coil of the second electrode 112, when the second electrode 112 is in a flattened state, satisfies: 0 ≤ P ≤ 4p. This ensures that the multiple sets of through holes 20 of the core 10 are approximately evenly distributed along the circumferential direction C of the core 10, which can improve the electrolyte diffusion efficiency and venting efficiency at different positions of the core 10, further improving the liquid injection efficiency and wetting efficiency, and reducing the risk of lithium plating. Furthermore, the positioning tolerance p mm of the through holes 21 also satisfies: 0 < p ≤ 0.5, which depends on the positioning accuracy of the drilling equipment.

[0039] Furthermore, in this embodiment of the application, both the first electrode 111 and the second electrode 112 are provided with through holes 21. Of course, in other embodiments of this application, only the first electrode 111 or only the second electrode 112 may be provided with through holes 21, depending on the position of the liquid injection hole of the single cell, the lead-out direction and method of the positive electrode tab and the negative electrode tab.

[0040] The first electrode 111 of the present application embodiment will be described below.

[0041] In one embodiment, the first electrode 111 is provided with multiple sets of through-hole groups 20, each through-hole group 20 including multiple through holes 21. For example... Figure 1 As shown, Figure 1The location of the through-holes 21 is shown. The through-holes 21 penetrate the first electrode 111 along the radial direction X of the core 10. Two adjacent through-holes 21 in the through-hole group 20 are positioned opposite each other, meaning they are interconnected. This allows the electrolyte to diffuse rapidly along the radial direction X of the core 10 through the multiple through-holes 21 in the through-hole group 20, improving the electrolyte diffusion efficiency and thus enhancing the injection and wetting efficiency. Furthermore, the gas inside the core 10 can be vented through the multiple through-holes 21 in the through-hole group 20, improving venting efficiency and reducing the risk of lithium plating. This, in turn, improves the performance of the individual cells, increasing their production efficiency and yield.

[0042] Specifically, the core 10 has a central through hole 16 extending along its axial direction Z in its middle portion, which is used for injecting electrolyte. In the radial direction X of the core 10, each through hole 21 in the through hole group 20 is positioned opposite to the central through hole 16, meaning that each through hole 21 in the through hole group 20 is interconnected with the central through hole 16. Thus, the electrolyte injected into the central through hole 16 can rapidly diffuse along the radial direction X of the core 10 through the multiple through holes 21 in the through hole group 20, improving the electrolyte diffusion efficiency and thus enhancing the injection and wetting efficiency.

[0043] In one embodiment, such as Figure 5 As shown, in the radial direction X of the core 10, each through hole 21 in the through hole group 20 is distributed in adjacent multiple turns of the first electrode 111, such that each turn of the first electrode 111 has multiple through holes 21. The first electrode 111 has a flattening direction T in the flattened state, and the positioning tolerance of the through holes 21 is p mm. When the first electrode 111 is in the flattened state and in the same turn of the first electrode 111, the difference in distance between any two adjacent through holes 21 in the flattening direction T is P mm, satisfying: 0≤P≤4p. In other words, the multiple through hole groups 20 of the core 10 of this application are approximately uniformly distributed in the circumferential direction C of the core 10, which can improve the electrolyte diffusion efficiency and venting efficiency at different positions of the core 10, further improve the liquid injection efficiency and wetting efficiency, and help reduce the risk of lithium plating.

[0044] It should be noted that in this embodiment, when the first electrode 111 is in a flattened state and within the same coil of the first electrode 111, the theoretical difference in distance between any two adjacent through holes 21 in the flattening direction T is 0 mm. This ensures that the multiple sets of through holes 20 of the core 10 are distributed as evenly as possible along the circumferential direction C of the core 10. Since the through holes 21 have a positioning tolerance p mm, the difference in distance P mm between any two adjacent through holes 21 in the flattening direction T within the same coil of the first electrode 111 satisfies: 0 ≤ P ≤ 4p. This ensures that the multiple sets of through holes 20 of the core 10 are distributed approximately evenly along the circumferential direction C of the core 10, which can improve the electrolyte diffusion efficiency and venting efficiency at different positions of the core 10, further improving the liquid injection efficiency and wetting efficiency, and reducing the risk of lithium plating.

[0045] In one embodiment, when the first electrode 111 is in a flattened state, the distance between two through holes 21 belonging to the same through hole group 20 on the nth and (n+1)th turns of the second electrode 112 in the flattening direction T is D. n mm, satisfying: D n+1 -D n = 2π(a+b+2s), where the thickness of the first electrode 111 is a mm, the thickness of the second electrode 112 is b mm, and the thickness of the diaphragm 12 (i.e., the first diaphragm 121 and the second diaphragm 122) is s mm. In this way, after the first electrode 111 is wound, two adjacent through holes 21 belonging to the same through hole group 20 can be arranged opposite each other in the radial X direction of the core 10, that is, the two adjacent through holes 21 can be interconnected in the radial X direction of the core 10, so that the electrolyte can diffuse rapidly along the radial X direction of the core 10 through the multiple through holes 21 in the through hole group 20, which can improve the diffusion efficiency of the electrolyte, which is beneficial to improving the injection efficiency and wetting efficiency. In addition, the gas inside the core 10 can also be vented through the multiple through holes 21 in the through hole group 20, which can improve the venting efficiency. Especially in the multi-turn first electrode 111 formed by winding, the gas at the first electrode 111 in the middle turn can also be vented through the multiple through holes 21 in the through hole group 20, which can improve the venting efficiency.

[0046] In one embodiment, the through holes 21 in the through hole group 20 are sequentially numbered in the radial direction X of the core 10, from the inside of the core 10 towards the outside, and the total number of through holes 21 in the through hole group 20 is N. One end of the first electrode 111 is a winding end (i.e., the first winding end 113), and the first electrode 111 is wound around the first winding end 113. When the first electrode 111 is in a flattened state, the distance between each through hole 21 in the through hole group 20 and the first winding end 113 in the flattening direction T is L. n mm, where n is 1, 2, 3…N, satisfying: L n=nL1+n(n-1)D / 2. In this way, after the first electrode 111 is wound, two adjacent through holes 21 belonging to the same through hole group 20 can be arranged opposite each other in the radial X direction of the core 10, that is, the two adjacent through holes 21 can be interconnected in the radial X direction of the core 10, so that the electrolyte can diffuse rapidly along the radial X direction of the core 10 through the multiple through holes 21 in the through hole group 20, which can improve the diffusion efficiency of the electrolyte, which is beneficial to improving the injection efficiency and wetting efficiency. In addition, the gas inside the core 10 can also be vented through the multiple through holes 21 in the through hole group 20, which can improve the venting efficiency.

[0047] In one embodiment, the first electrode 111 includes a first coated portion 131, a first empty foil portion 141, and a first tab 151 distributed along the axial direction Z of the core 10. A through hole 21 is formed in the first empty foil portion 141. The first coated portion 131 is the part of the first electrode 111 coated with active material and ceramic material, and the first empty foil portion 141 is the part between the first coated portion 131 and the first tab 151 that is not coated with active material and ceramic material. In this way, this embodiment not only facilitates the processing of the through hole 21 on the first electrode 111, but also avoids the risks of affecting the cycle performance of the first electrode 111 and causing short circuits due to the through hole 21 being located in the first coated portion 131.

[0048] In one embodiment, the diameter of the through hole 21 is d mm, and the dimension of the first empty foil portion 141 in the axial Z direction of the core 10 is M mm, satisfying: p ≤ d ≤ M. Optionally, the dimension M of the first empty foil portion 141 in the axial Z direction of the core 10 is... mm also satisfies: 0.5 ≤ M ≤ 10, for example, M can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, Any value from 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0.

[0049] In this embodiment, the through hole 21 is circular in shape. By reasonably setting the diameter of the through hole 21, it is possible not only to ensure that the through hole 21 can be set in the first empty foil portion 141, but also to ensure that after the first electrode sheet 111 is wound, two adjacent through holes 21 belonging to the same through hole group 20 can be arranged opposite each other in the radial X direction of the core 10. That is, the two adjacent through holes 21 can be interconnected in the radial X direction of the core 10, so that the electrolyte can diffuse rapidly along the radial X direction of the core 10 through the multiple through holes 21 in the through hole group 20, which can improve the diffusion efficiency of the electrolyte and is beneficial to improve the injection efficiency and wetting efficiency. In addition, the gas inside the core 10 can also be vented through the multiple through holes 21 in the through hole group 20, which can improve the venting efficiency.

[0050] Of course, in other embodiments of this application, the shape of the through hole 21 can be rectangular, trapezoidal, etc., and is not limited here.

[0051] The second electrode 112 of the present application embodiment will be described below.

[0052] In one embodiment, such as Figure 6 As shown, when the second electrode 112 is in a flattened state, the distance between two through holes 21 belonging to the same through hole group 20 on the nth and (n+1)th turns of the second electrode 112 in the flattening direction T is D. n mm, satisfying: D n+1 -D n = 2π(a+b+2s), where the thickness of the first electrode 111 is a mm, the thickness of the second electrode 112 is b mm, and the thickness of the diaphragm 12 (i.e., the first diaphragm 121 and the second diaphragm 122) is s mm. In this way, after the second electrode 112 is wound, two adjacent through holes 21 belonging to the same through hole group 20 can be arranged opposite each other in the radial direction X of the core 10, meaning that the two adjacent through holes 21 can communicate with each other in the radial direction X of the core 10. This allows the electrolyte to diffuse rapidly along the radial direction X of the core 10 through multiple through holes 21 in the through hole group 20, improving the electrolyte diffusion efficiency and thus improving the injection and wetting efficiency. Furthermore, the gas inside the core 10 can also be vented through multiple through holes 21 in the through hole group 20, improving venting efficiency. Especially in the multi-turn second electrode 112 formed by winding, the gas at the middle turn of the second electrode 112 can also be vented through multiple through holes 21 in the through hole group 20, further improving venting efficiency.

[0053] In one embodiment, the through holes 21 in the through hole group 20 are sequentially numbered in the radial direction X of the core 10, from the inside of the core 10 towards the outside, and the total number of through holes 21 in the through hole group 20 is N. One end of the second pole piece 112 is a winding end (i.e., the second winding end 114), and the second pole piece 112 is wound around the second winding end 114. When the second pole piece 112 is in a flattened state, the distance between each through hole 21 in the through hole group 20 and the second winding end 114 in the flattening direction T is L. n mm, where n is 1, 2, 3…N, satisfying: L n =nL1+n(n-1)D / 2. In this way, after the second electrode 112 is wound, two adjacent through holes 21 belonging to the same through hole group 20 can be arranged opposite each other in the radial X direction of the core 10, that is, the two adjacent through holes 21 can be interconnected in the radial X direction of the core 10, so that the electrolyte can diffuse rapidly along the radial X direction of the core 10 through the multiple through holes 21 in the through hole group 20, which can improve the diffusion efficiency of the electrolyte, which is beneficial to improving the injection efficiency and wetting efficiency. In addition, the gas inside the core 10 can also be vented through the multiple through holes 21 in the through hole group 20, which can improve the venting efficiency.

[0054] In one embodiment, the second electrode 112 includes a second coated portion 132, a second empty foil portion 142, and a second tab 152 distributed along the axial direction Z of the core 10. A through hole 21 is formed in the second empty foil portion 142. The second coated portion 132 is the part of the second electrode 112 coated with active material and ceramic material, and the second empty foil portion 142 is the part between the second coated portion 132 and the second tab 152 that is not coated with active material and ceramic material. In this way, this embodiment not only facilitates the processing of the through hole 21 on the second electrode 112, but also avoids the risks of affecting the cycle performance of the second electrode 112 and causing short circuits due to the through hole 21 being located in the second coated portion 132.

[0055] In one embodiment, the diameter of the through hole 21 is d mm, and the dimension of the second empty foil portion 142 in the axial Z direction of the core 10 is M mm, satisfying: p ≤ d ≤ M. Optionally, the dimension M of the second empty foil portion 142 in the axial Z direction of the core 10 is... mm also satisfies: 0.5 ≤ M ≤ 10, for example, M can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, Any value from 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0.

[0056] In this embodiment, the through hole 21 is circular in shape. By reasonably setting the diameter of the through hole 21, it is possible not only to ensure that the through hole 21 can be set in the second empty foil portion 142, but also to ensure that after the second electrode sheet 112 is wound, two adjacent through holes 21 belonging to the same through hole group 20 can be arranged opposite each other in the radial X direction of the core 10. That is, the two adjacent through holes 21 can be interconnected in the radial X direction of the core 10, so that the electrolyte can diffuse rapidly along the radial X direction of the core 10 through the multiple through holes 21 in the through hole group 20, which can improve the diffusion efficiency of the electrolyte and is beneficial to improve the injection efficiency and wetting efficiency. In addition, the gas inside the core 10 can also be vented through the multiple through holes 21 in the through hole group 20, which can improve the venting efficiency.

[0057] Of course, in other embodiments of this application, the shape of the through hole 21 can be rectangular, trapezoidal, etc., and is not limited here.

[0058] In one embodiment, the core 10 may adopt a double-sided tab design, with the positive tab at one end along its axial direction Z and the negative tab at the other end. Specifically, the first tab 151 of the first electrode 111 and the second tab 152 of the second electrode 112 are respectively located at both ends of the core 10 along its axial direction Z, and both the first empty foil portion 141 and the second empty foil portion 142 are provided with through holes 21.

[0059] like Figure 3 and Figure 4 As shown, in the radial direction X of the core 10, the end of the first coating portion 131 away from the first empty foil portion 141 is disposed opposite to the second coating portion 132, and the end of the second coating portion 132 away from the second empty foil portion 142 is disposed opposite to the first coating portion 131. In other words, in this embodiment, the first coating portion 131 of the first electrode 111 does not block the second empty foil portion 142 of the second electrode 112, that is, the first coating portion 131 of the first electrode 111 does not block the through holes 21 on the second empty foil portion 142, which can avoid affecting the diffusion and venting of the electrolyte through the multiple through holes 21 in the through hole group 20; similarly, in this embodiment, the second coating portion 132 of the second electrode 112 does not block the first empty foil portion 141 of the first electrode 111, that is, the second coating portion 132 of the second electrode 112 does not block the through holes 21 on the first empty foil portion 141, which can avoid affecting the diffusion and venting of the electrolyte through the multiple through holes 21 in the through hole group 20.

[0060] In summary, this application provides a single-cell battery and a battery pack. The core of the single-cell battery has multiple sets of through-hole groups, each of which includes multiple through-holes. In the radial direction of the core, adjacent through-holes in each through-hole group are arranged opposite to each other, meaning they are interconnected. This allows the electrolyte to diffuse rapidly along the radial direction of the core through the multiple through-holes in the through-hole groups, improving electrolyte diffusion efficiency and thus improving injection and wetting efficiency. Furthermore, gases inside the core can be vented through the multiple through-holes in the through-hole groups, improving venting efficiency and reducing the risk of lithium plating, thereby improving the performance of the single-cell battery.

[0061] Furthermore, in the radial direction of the core, each through-hole in the through-hole group is distributed across multiple adjacent turns of the second electrode sheet, resulting in multiple through-holes on each turn of the second electrode sheet. When the second electrode sheet is in a flattened state and within the same turn of the second electrode sheet, the difference in distance between any two adjacent through-holes in the flattened direction is P mm, satisfying: 0 ≤ P ≤ 4p. In other words, the multiple through-hole groups in the core of this application are approximately uniformly spaced in the circumferential direction of the core, which can improve the electrolyte diffusion efficiency and venting efficiency at different locations of the core, further improving the electrolyte injection efficiency and wetting efficiency, and reducing the risk of lithium plating.

[0062] To better understand the technical solution of this application, the following explanation uses a lithium-ion battery as an example.

[0063] This test example provides a method for preparing a lithium-ion battery, the specific process of which is as follows:

[0064] 1. Preparation of positive electrode sheet

[0065] The positive electrode active material, conductive agent, and binder are mixed according to the mass ratio, and then a solvent is added for further mixing. The mixture is stirred under vacuum until the system becomes homogeneous, thus obtaining a positive electrode slurry. The positive electrode slurry is then uniformly coated on both sides of the positive electrode current collector, and then transferred to an oven for drying. After rolling, slitting, and cutting, the positive electrode sheet is obtained.

[0066] 2. Preparation of negative electrode sheet

[0067] The negative electrode active material, conductive agent, thickener, and binder are mixed according to a mass ratio, and then a solvent is added for further mixing. The mixture is stirred under vacuum until the system becomes homogeneous, yielding a negative electrode slurry. This slurry is then uniformly coated on both sides of the negative electrode current collector, transferred to an oven for drying, and subsequently rolled, slit, and cut to obtain the negative electrode sheet. Multiple through holes 21 are punched into the negative electrode sheet to form a through hole group 20. Each through hole 21 in the through hole group 20 is distributed across multiple adjacent rings of the negative electrode sheet, resulting in multiple through holes 21 on each ring. The negative electrode sheet has a flattening direction T when flattened, and the positioning tolerance of the through holes 21 is p mm. When the negative electrode sheet is flattened and within the same ring, the difference in distance between any two adjacent through holes 21 in the flattening direction T is P mm, satisfying: 0 ≤ P ≤ 4p. Some negative electrode sheets still use the traditional method and do not have through hole groups 20.

[0068] 3. Preparation of electrolyte

[0069] An organic solvent is obtained by mixing multiple solvents in a certain mass ratio, and then an electrolyte is added and mixed evenly to prepare an electrolyte solution.

[0070] 4. Preparation of the diaphragm

[0071] PP film is used as the separator.

[0072] 5. Preparation of lithium-ion batteries

[0073] After drying, the negative and positive electrode sheets prepared by the above steps are used together with the separator to prepare a wound electrode assembly using a winding machine. The different posts on the end caps of the positive and negative electrode tabs are directly welded together, and the welded electrode assembly with the top cap is placed into an aluminum shell for encapsulation. After filling with electrolyte and forming and fixing the volume, a lithium-ion battery is obtained. Using a stopwatch or the timer built into the electrolyte injection system, record the time taken for a single cell in an embodiment where multiple through holes 21 are punched into the negative electrode to form a through hole group 20. Each through hole 21 in the through hole group 20 is distributed in adjacent rings of negative electrode sheets, so that each ring of negative electrode sheet has multiple through holes 21. The negative electrode sheet has a flattening direction T when it is flattened. The positioning tolerance of the through hole 21 is p mm. When the negative electrode sheet is flattened and in the same ring of negative electrode sheets, the difference in distance between any two adjacent through holes 21 in the flattening direction T is P mm. For a single cell in an embodiment where 0≤P≤4p, the time taken for the electrolyte injection is S from the insertion of the electrolyte injection plug into the electrolyte injection hole to the completion of electrolyte injection (see Table 1 Test Examples 1-29 for details). Then, record the electrolyte injection time of the comparative single cell provided by the conventional scheme (see Table 1 Test Examples 30 and 31 for details).

[0074] The lithium-ion batteries in each test case were prepared according to the above-mentioned preparation method. The structural dimensions and performance test data of each test case are shown in Table 1 and Table 2.

[0075] The lithium-ion single cells prepared in the above test examples were subjected to performance testing. The specific test methods are as follows:

[0076] The single-cell battery testing system used for performance testing must support constant current charging and discharging, constant voltage charging, and data recording. The system has a constant temperature chamber to control the ambient temperature at 25±1℃. Multimeters (calibrated for voltage / current), data cables, insulating clamps, micrometers, vernier calipers, etc. are used to measure various data.

[0077] Before measurement, the lithium-ion cells need to be pretreated. The steps include:

[0078] 1) Initial activation: Perform 1-2 complete charge-discharge cycles at a low charge-discharge rate (e.g., 0.2C) to bring the lithium-ion single cell to a stable state.

[0079] 2) Let it stand for 10-30 minutes after each charge and discharge cycle to ensure that polarization is eliminated.

[0080] Before conducting a charge / discharge rate test, a suitable charge / discharge rate should be selected. For battery life testing, a 2C rate can be used.

[0081] The testing process for lithium-ion single-cell batteries includes:

[0082] 1) During the charging phase, constant current charging is performed first, followed by constant voltage charging: first, constant current charging is performed at the standard rate (e.g., 0.5C) until the cutoff voltage (e.g., 4.2V), then the constant voltage mode is switched and the charging stops when the current drops to the cutoff current (e.g., 0.05C).

[0083] 2) Set a preset time for standing, for example, 10 minutes.

[0084] 3) Discharge stage: The discharge stage is carried out in the form of constant current discharge, such as constant current discharge at the target rate (e.g., 1C) until the cutoff voltage (e.g., 2.5V or 3.0V, depending on the material).

[0085] 4) Let it stand for the preset time again, for example, 10 minutes.

[0086] 5) Repeated test: Charge and discharge test at the battery life test rate of 2C, repeated 1200 times.

[0087] Finally, data were recorded and analyzed for key parameters such as discharge capacity, charging capacity, and surface temperature of individual cells. The ratio of the discharge capacity after 1200 cycles of 2C charge and discharge to the rated capacity (the capacity obtained by testing at 0.2C charge and discharge) was determined. The ratio of the discharge capacity to the rated capacity is the remaining percentage of the individual cell capacity.

[0088] The lithium-ion batteries prepared in the above test examples were subjected to performance testing. The specific testing methods are as follows:

[0089] Table 1. Parameters and test results for test examples 1-31

[0090]

[0091] The individual cells used in Test Examples 1-29 are all individual cells provided in this application, while the individual cells used in Test Examples 30 and 31 are individual cells of conventional schemes. As can be seen from the above test examples, the single-cell battery provided in each embodiment of this application has a longer service life and a shorter liquid injection time. This is due to the fact that the core 10 has multiple sets of through-hole groups 20, each of which includes multiple through holes 21. In the radial direction X of the core 10, the through holes 21 penetrate the second electrode 112. Each through hole 21 in the through-hole group 20 is distributed in adjacent multiple turns of the second electrode 112, so that each turn of the second electrode 112 has multiple through holes 21. In the radial direction X, two adjacent through holes 21 in the through-hole group 20 are arranged opposite each other. The second electrode 112 has a flattening direction T in the flattened state, and the positioning tolerance of the through hole 21 is p mm. In the flattened state of the second electrode 112 and in the same turn of the second electrode 112, the difference in distance between any two adjacent through holes 21 in the flattening direction T is P mm, which satisfies: 0≤P≤4p. In this way, multiple sets of through holes 20 are approximately evenly spaced on the circumferential C of the core 10, which improves the electrolyte diffusion efficiency and venting efficiency at different positions of the core 10, thereby improving the liquid injection efficiency and wetting efficiency, and reducing the risk of lithium plating.

[0092] The single-cell battery and battery pack provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A single-cell battery, characterized in that, include: case; as well as A core (10) having a radial (X) orientation is disposed within the housing; The core (10) is formed by stacking and winding a first electrode (111), a first diaphragm (121), a second electrode (112), and a second diaphragm (122); the core (10) has multiple sets of through-hole groups (20), each of the through-hole groups (20) includes multiple through-holes (21); in the radial direction (X) of the core (10), the through-holes (21) penetrate the second electrode (112), and each of the through-holes (21) in the through-hole group (20) is distributed on adjacent multiple turns of the second electrode (112), so that each turn of the second electrode (112) has multiple through-holes (21), and in the radial direction (X), two adjacent through-holes (21) in the through-hole group (20) are arranged opposite to each other; The second electrode (112) has a flattening direction (T) in the flattened state, and the positioning tolerance of the through hole (21) is p mm; when the second electrode (112) is in the flattened state and in the same circle of the second electrode (112), the difference in distance between any two adjacent through holes (21) in the flattening direction (T) is P mm, which satisfies: 0≤P≤4p.

2. The single-cell battery according to claim 1, characterized in that, With the second electrode plate (112) in a flattened state, the distance between two through holes (21) belonging to the same through hole group (20) on the second electrode plate (112) of the nth and (n+1)th turns in the flattening direction (T) is D. n mm, satisfying: D n+1 -D n =2π(a+b+2s), wherein the thickness of the first electrode (111) is a mm, the thickness of the second electrode (112) is b mm, the thickness of the first diaphragm (121) is s mm, and the thickness of the second diaphragm (122) is s mm.

3. The single-cell battery according to claim 2, characterized in that, On the radial (X) direction of the core (10), each of the through holes (21) in the through hole group (20) is sequentially numbered in the direction from the inside of the core (10) to the outside, and the total number of the through holes (21) in the through hole group (20) is N; one end of the second pole piece (112) is a winding end (114), and the second pole piece (112) is wound around the winding end (114); When the second electrode (112) is in a flattened state, the distance between each through hole (21) in the through hole group (20) and the winding end (114) in the flattening direction (T) is L. n mm, where n is 1, 2, 3…N, satisfying: L n = nL1+n(n-1)D / 2.

4. The single-cell battery according to claim 1, characterized in that, The second electrode (112) includes a second coating portion (132), a second empty foil portion (142), and a second electrode tab (152) distributed along the axial direction (Z) of the core (10), and the second empty foil portion (142) is provided with the through hole (21).

5. The single-cell battery according to claim 4, characterized in that, The diameter of the through hole (21) is d mm, and the dimension of the second empty foil portion (142) in the axial (Z) direction of the core (10) is M mm, satisfying: p≤d≤M.

6. The single-cell battery according to claim 1 or 5, characterized in that, The positioning tolerance p mm of the through hole (21) also satisfies: 0 < p ≤ 0.

5.

7. The single-cell battery according to claim 5, characterized in that, The second empty foil portion (142) has a dimension M mm in the axial (Z) direction of the core (10) that also satisfies: 0.5 ≤ M ≤ 10.

8. The single-cell battery according to claim 1, characterized in that, The first electrode (111) includes a first coating portion (131), a first empty foil portion (141), and a first electrode tab (151) distributed along the axial direction (Z) of the core (10). The first empty foil portion (141) has the through hole (21). The second electrode (112) includes a second coating portion (132), a second empty foil portion (142), and a second electrode tab (152) distributed along the axial direction (Z) of the core (10). The second empty foil portion (142) has the through hole (21). Wherein, the first tab (151) is located at one end of the core (10) in its axial direction (Z), and the second tab (152) is located at the other end of the core (10) in its axial direction (Z); in the radial direction (X) of the core (10), the end of the first coating portion (131) away from the first empty foil portion (141) is disposed opposite to the second coating portion (132), and the end of the second coating portion (132) away from the second empty foil portion (142) is disposed opposite to the first coating portion (131).

9. The single-cell battery according to claim 1, characterized in that, The core (10) has a central through hole (16) that extends through it along its axial direction (Z); in the radial direction (X) of the core (10), each of the through holes (21) in the through hole group (20) is arranged opposite to the central through hole (16).

10. A battery pack, characterized in that, It includes a housing and a single battery cell as described in any one of claims 1 to 9, wherein the single battery cell is disposed in the housing.

Images