A cylindrical battery and a structure to protect the foil at the end of the winding core from breakage

Abstract

A structure for preventing the foil from breaking at the end of a winding core of a cylindrical battery, characterized in that the structure for preventing the foil from breaking at the end of the winding core consists of a wound positive electrode and a wound negative electrode, wherein a separating membrane is arranged between the positive and the negative electrode; A first insulating layer is provided at the end of the positive electrode; areas for the positive electrode material are provided on both the concave and convex sides of the positive electrode; part of the first insulating layer covers the areas for the positive electrode material on the concave and convex sides at the end of the positive electrode; the starting point of the first insulating layer, which covers the areas for the positive electrode material, is defined as the first pressing point; The end piece of the negative pole has an uncoated film on which an outer pole attachment is arranged; the center point of the outer pole attachment in the circumferential direction is defined as the second pressure point; Between the first and second pressing points there is a predetermined arc length, wherein the angle of the circular angle formed by the predetermined arc length to the center of the winding core is 120° to 240°.

Description

Technical area

[0001] The present description concerns the field of battery technology, in particular a cylindrical battery and a structure for protecting the foil at the end of the winding core from breakage. Technology in the background

[0002] In the manufacture of cylindrical batteries, the positive electrode, separator foil, and negative electrode are formed into a round core during the winding process; however, in practice, the core's roundness is not perfect. The reasons for this are: 1. One or more terminals are welded to the positive and negative electrodes, resulting in a difference in terminal thickness along the diameter; 2. The cathode foil at the end of the cathode section of the core is coated, while the outermost cathode foil is uncoated, leading to a height difference between coated and uncoated areas along the diameter; 3. Stress build-up occurs in the electrode foils during the winding process, resulting in inherently imperfect roundness and unevenness along the diameter.In summary, when a coil core has imperfect roundness, after insertion into the steel housing, the areas of greater thickness in the diameter direction – particularly at the end of the positive electrode at 12' and at the outer connection of the negative electrode at 5' – come into direct contact with the steel housing or have only minimal expansion space. As a result, they are compressed when inserted into the housing or when the coil core expands within the steel housing, as shown in [reference]. Fig. 1 shown.

[0003] Furthermore, metal burrs may be present on the cut edges of the cathode foils after cutting. Since the individual components of the winding cores (cathode foil, separator, anode foil) are in close proximity, these metal burrs in the core area of ​​the cathode foil can puncture the separator during manufacturing or operation of the battery cell module, causing the cathode and anode foils to come into contact and resulting in an internal short circuit. To prevent this phenomenon, an industry-proven measure is to apply adhesive tape to both sides of the positive electrode at the beginning and end. This prevents burrs from puncturing the separator foil after the positive electrode material has been cut, thus reducing the risk of an internal short circuit.

[0004] However, this design causes the winding core to thicken further in the radial direction at the end of the positive electrode due to the adhesive film. As the negative electrode expands during the cell's charging and discharging process, contact can easily occur between the area with the adhesive strip at the end of the positive electrode (i.e., at end 12' of the positive electrode) and the outer negative terminal 5' with the steel casing. This results in radial stress on the empty film area at the end of the negative electrode between these two points, leading to film rupture and negatively impacting the cell's internal resistance and cycle life. Content of the invention

[0005] With reference to Fig. 1 and Fig. 2. The inventors have determined that the main causes of foil breakage at the end of the anode are as follows: 1. Anode materials such as synthetic graphite tend to expand during the charging and discharging process, thereby exerting pressure on the electrode foil; this is the main cause of the change in the diameter of the winding core; 2. The material layer at the end of the positive electrode in the "Vest" structure is approximately 70 µm thick, with a height difference at the bonding point (the adhesive layer is approximately 25 µm to 32 µm thick). At the 12 o'clock position at the end of the positive electrode and at the 5 o'clock position at the outer terminal of the negative electrode, there is slight contact with the steel housing, resulting in radial stress on the negative electrode between these two points. 3. There is a height difference between the adhesive surface at the end of the positive electrode and the material area of ​​the positive electrode itself. The beginning of the adhesive tape pushes the negative electrode slightly outwards at this point, which can lead to breakage of the negative electrode; 4. The outermost layer of the negative electrode on the winding core is constricted by the end tape and the steel housing and cannot transmit the pressure acting upon it outwards. Since the modulus of elasticity of the empty foil area in the outermost layer of the negative electrode is relatively low, fractures easily occur in this area.

[0006] In summary, it can be said that in the area of ​​the negative foil gap between the end 12' of the positive electrode and the outer negative tab 5' there is a risk of foil breakage at the corresponding points of the negative electrode.

[0007] In view of the shortcomings of the prior art, one objective of this description is to provide a cylindrical battery and a foil breakage protection structure for the end of the winding core that effectively reduces the risk of foil breakage at the end of the positive electrode and at the outer negative tab, as well as at the negative electrode between these two points.

[0008] To achieve the aforementioned objective, the present description provides a structure for protection against foil breakage at the end of the winding core of a cylindrical battery, wherein said structure for protection against foil breakage at the end of the winding core consists of a wound positive and a negative electrode foil, wherein a separating membrane is arranged between the positive and the negative electrode foil; wherein a first insulating layer is arranged at the endpoint of the positive electrode foil; wherein both the concave and the convex sides of the positive electrode foil are provided with a positive material region; the first insulating layer partially covers the anode material regions on the concave and the convex sides at the endpoint of the anode foil; the initial region of the first insulating layer, which covers the anode material regions, is defined as the first pressure point;The end piece of the negative electrode has an uncoated foil on which an outer negative electrode tab is arranged; the center point of the outer negative electrode tab in the circumferential direction is defined as the second pressing point; between the first and the second pressing point there is a predetermined arc length, wherein the angle of the center point of this predetermined arc length to the center point of the winding core is 120° to 240°.

[0009] In a preferred embodiment, the angle between the predetermined arc length and the center of the winding core is 150° to 210°.

[0010] In a preferred embodiment, the angle between the predetermined arc length and the center of the winding core is 180°.

[0011] In a preferred embodiment, both the concave and the convex sides of the outer negative electrode tab are provided with a second insulating layer.

[0012] In a preferred embodiment, the film areas on which the concave and convex sides of the outer negative connecting tubes are provided with a second insulating layer are uncoated film areas.

[0013] In a preferred embodiment, the first insulating layer and / or the second insulating layer are insulating adhesive tapes.

[0014] In a preferred embodiment, the insulating tape of the first insulating layer consists of PI, while the insulating tape of the second insulating layer consists of PET.

[0015] In a preferred embodiment, a first foil space is provided at the end section of the positive electrode, wherein the positive electrode region is not arranged on either the concave or the convex side of the first foil space, and wherein the first insulating layer covers at least part of the concave and part of the convex side of the first foil space.

[0016] In a preferred embodiment, a second foil space is provided on the convex side at the end section of the negative electrode, wherein the second foil space is located on the outermost layer of the winding core and covers the area in which the intended arc length is located.

[0017] In a preferred embodiment, the length of the second film space is at least twice the circumference of the outermost layer of the winding core.

[0018] The present invention further relates to a cylindrical battery comprising a structure for preventing foil breakage at the end of the winding core; wherein the structure for preventing foil breakage at the end of the winding core consists of a wound positive electrode and a wound negative electrode, with a separating membrane arranged between the positive and the negative electrode; wherein a first insulating layer is provided at the end section of the positive electrode; wherein a region for the positive electrode material is provided on both the concave and the convex side of the positive electrode; the first insulating layer partially covers the anode material regions on the concave and the convex side at the end region of the anode foil; the initial region of the first insulating layer, which covers the anode material regions, is defined as the first compression point;The end piece of the negative electrode has an uncoated foil on which an outer negative electrode tab is arranged; the center point of the outer negative electrode tab in the circumferential direction is defined as the second pressing point; between the first and the second pressing point there is a predetermined arc length, wherein the angle of the center point of this predetermined arc length to the center point of the winding core is 120° to 240°.

[0019] Advantages:

[0020] The structure presented in this embodiment for preventing foil breakage at the end of the winding core of the cylindrical battery has a predetermined arc length between the end of the positive electrode and the outer negative tab. By limiting the angle between this predetermined arc length and the center of the winding core to between 120° and 240°, the distance between the end of the positive electrode and the outer negative tab can be adjusted, thereby increasing the foil tension that the corresponding areas of the negative electrode (the area without foil at the end of the negative electrode and the area with negative material) can withstand. This avoids the effects of the winding core expansion and the pressure from the steel casing during the charging and discharging process, so that the negative electrode at the end of the positive electrode (i.e.,at the point of the first insulating layer) and the outer negative terminal (including the areas of the negative electrode corresponding to the end of the positive electrode and the outer negative terminal) does not break so easily, i.e. the risk of foil breakage at the end of the positive electrode, at the outer negative terminal and in the areas in between of the negative electrode is effectively reduced.

[0021] With reference to the following explanations and the accompanying drawings, a specific embodiment of the present invention is disclosed in detail, showing how the principle of the present invention can be implemented. It is understood that the scope of the embodiments of the present invention is not thereby limited.

[0022] Features described and / or illustrated in relation to one embodiment may be used in the same or similar way in one or more other embodiments, combined with features of other embodiments, or used in place of features of other embodiments.

[0023] It should be noted that the term “includes / contains”, as used in the present description, denotes the presence of features, parts, steps or components, but does not exclude the presence or addition of one or more other features, parts, steps or components. Description of the attached drawings

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings necessary for describing the embodiments or the prior art are briefly presented below. It goes without saying that the drawings described below represent only some embodiments of the present invention; a person skilled in the art can easily develop further embodiments based on these drawings. Fig. Figure 1 shows a schematic representation of the winding core structure of a cylindrical battery according to the state of the art; Fig. Figure 2 shows a schematic representation of the winding core structure of another cylindrical battery according to the prior art; Fig.Figure 3 shows a schematic representation of the structure of a foil breakage protection device at the end of the winding core of a cylindrical battery according to the present invention; Fig. Figure 4 shows a schematic representation of the unfolded structure of the winding core from the vicinity of the first pressing point to the vicinity of the second pressing point. Fig. 3; Fig. Figure 5 shows a schematic representation of the change in internal resistance value after 100 cycles in the cell cycle test when the angle between the first and second pressing points and the center of the winding core is 240°; Fig. Figure 6 shows a schematic representation of the change in the internal resistance value during a cycle test of the cell over 100 cycles when the angle between the first and second pressing points and the center of the winding core is 204°; Fig. 7 and Fig.Figure 8 shows schematic representations of the winding core structure when the angle between the first and second pressing points and the center of the winding core is 150° or 210°, respectively.

[0025] Description of the attached markings: In the prior art: 12', end section of the positive electrode; 5', outer connection of the negative electrode;

[0026] In the present application: 1, positive electrode; 11, material area of ​​the positive electrode; 12, end section of the positive electrode; 13, aluminum foil; 2, negative electrode; 21, material area of ​​the negative electrode; 22, second foil clearance; 23, copper foil; 4, first insulating layer; 5, outer negative tab; 6, second insulating layer; 7, separator; A, first pressure point; B, second pressure point; F1, foil tensile force; F2, expansion force. Detailed description

[0027] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the embodiments of the present invention are clearly and completely described below with reference to the accompanying drawings. It is understood that the described embodiments represent only a portion of the embodiments of the present invention and do not encompass all embodiments. All further embodiments that a person skilled in the art in this field arrives at based on the embodiments of the present invention without any inventive effort should fall within the scope of protection of the present invention.

[0028] It should be noted that when an element is described as "arranged on another element," it may be directly attached to another element or located in the center of another element. When an element is described as "connected to another element," it may be directly connected to another element or simultaneously located in the center of another element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this description are for illustrative purposes only and do not represent any single embodiment.

[0029] Unless otherwise defined, all technical and scientific terms used in this description have the same meaning as they would normally be understood by a person skilled in the art in the field of the present invention. The terms used in this description of the present invention serve only to describe specific embodiments and are not intended to limit the invention. The term "and / or" used in this description includes any and all combinations of one or more of the elements listed.

[0030] With reference to the Fig. 1 and Fig. 2 is in Fig. 1 the negative electrode of the winding core structure broke near the end section 12' of the positive electrode, while in Fig.2. The negative electrode of the winding core structure is broken between the end section 12' of the positive electrode and the outer negative tab 5'. Simultaneously, we have established in the prior art that the negative foil can also break between the end point 12' of the positive electrode and the outer negative tab 5' (including the end point 12' of the positive electrode and the outer negative tab 5' itself). This confirms that the break essentially occurs along the predetermined arc length L between the first pressure point A and the second pressure point B. Since this section of the negative electrode foil exceeds the maximum elongation limit of the foil under radial expansion and compression, it breaks.

[0031] To solve the fraction problem described above, see the Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig.8: The present embodiment of the application provides a structure for preventing breakage of the foil at the end of the winding core of a cylindrical battery, wherein this structure consists of a wound positive electrode 1 and a wound negative electrode 2, between which a separating membrane 7 is arranged. The separating membrane 7 may comprise a first separating membrane and a second separating membrane. The first separating membrane is located between the convex side of the positive electrode 1 and the concave side of the negative electrode 2, while the second separating membrane is located between the concave side of the positive electrode 1 and the convex side of the negative electrode 2. It should be noted that in the present application, the “concave side” refers to the side facing the center, while the “convex side” refers to the side facing away from the center.

[0032] It should be noted that the structure provided in the present embodiment of the invention for preventing foil breakage at the end of the winding core of the cylindrical battery is formed by winding the positive electrode 1, the first separating foil, the negative electrode 2, and the second separating foil with a winding needle. The incoming end is the end that is wound first by the winding needle, i.e., the end closest to the center; the outgoing end is the end that is wound last by the winding needle, i.e., the end furthest from the center.

[0033] In this embodiment, a first insulating layer 4 is provided at the end section 12 of the positive electrode 1 to prevent metal burrs in the core of the positive electrode 1 from penetrating the membrane 7 and thereby causing an internal short circuit between the positive electrode 1 and the negative electrode 2. Both the concave and convex sides of the positive electrode 1 are provided with a positive electrode material region 11. A portion of the first insulating layer 4 must cover the anode material regions 11 on the concave and convex sides of the end section 12 of the anode foil 1. The starting point of the first insulating layer 4 that covers the anode material regions 11 is defined as the first pressure point A. At the first pressure point A, there is a sudden change in thickness because the first insulating layer 4 is located outside the anode material regions 11.At the end region of the negative electrode 2, there is uncoated foil material (the uncoated foil material corresponds to the second empty foil zone 22 described below, i.e., the copper foil 23, and is located near the outer circumference of the winding core), on which an outer negative tab 5 is provided. The point in the middle of the circumference of the outer negative tab 5 is defined as the second pressure point B. At the second pressure point B, due to the arrangement of the outer negative electrode tab 5 on the second foil space 22, there is a sudden change in thickness.

[0034] In this embodiment, the area between the first pressing point A and the second pressing point B has a predetermined arc length L, wherein the angle of the central angle opposite the predetermined arc length L is 120° to 240°. As in Fig.Figure 3 shows that the angle between the predetermined arc length L and the center of the winding core is defined as α (referred to in the present invention as the “central angle α”), wherein the central angle α has a value of 120° to 240° (including 120° and 240°).

[0035] In one embodiment, the end piece of the negative electrode 2 is located on the outermost layer of the winding core, so that the second pressing point B is also located on the outermost layer of the winding core. The end piece 12 of the positive electrode 1 is located on the second outermost layer of the winding core, so that the first pressing point A is also located on the second outermost layer of the winding core. Overall, this results in a structure in which the negative electrode surrounds the positive electrode.

[0036] The structure provided in this embodiment for preventing foil breakage at the end of the winding core of the cylindrical battery has a predetermined arc length L between the first pressing point A and the second pressing point B. By limiting the angle of the circle diameter opposite this predetermined arc length L to 120° to 240°, the length L between the first pressing point A and the second pressing point B can be adjusted to increase the foil tension F1, which the corresponding position of the anode foil 2 (the empty foil area at the end of the anode foil 2 and the anode material area 21) must withstand. As shown in Fig.As shown in Figure 3, the two points (the first pressure point A and the second pressure point B) are fixed. After the battery cell cycle, it expands repeatedly; this expansion force F2 acts radially and causes a change in the film tension F1 (strain rate of the film) at the outermost layer of the anode film 2 until the film tears upon reaching its maximum. The longer the film section between the first pressure point A and the second pressure point B, the greater the film tensile stress F1 it can withstand (the greater its total elongation length).

[0037] Therefore, the foil breakage protection design at the rear end of the winding core prevents the anode 2 from being affected by the expansion of the winding core and the pressure of the steel casing during the charging and discharging process, thus making the anode 2 less susceptible to breakage between the first pressure point A and the second pressure point B (including the anode 2 at the corresponding points at the first pressure point A and the second pressure point B). That is, the risk of foil breakage of the anode foil 2 at the first pressure point A, at the second pressure point B, and between these two points can be effectively reduced, thereby lowering the breakage rate of the anode foil 2 at the corresponding points from 10% to 2% or less.

[0038] In this embodiment, the positive electrode 1 comprises an aluminum foil 13, wherein two layers of the positive electrode material 11 are arranged on the concave and convex sides of the aluminum foil 13, respectively. A first foil cavity is provided at the end section 12 of the positive electrode 1 (aluminum foil 13), wherein no area of ​​the positive electrode material 11 is present on either the concave or the convex side of the first foil cavity. The first insulating layer 4 covers at least a portion of the concave and a portion of the convex side of the first foil cavity to prevent metal burrs in the core of the anode plate 1 from penetrating the separator foil 7 and thereby causing an internal short circuit between the anode plate 1 and the cathode plate 2. Preferably, the first insulating layer 4 completely covers both the concave and the convex sides of the first foil cavity.The end of the first insulating layer 4 is flush with the end of the aluminum foil 13.

[0039] Specifically, the first pressure point A is located at the position where the first insulating layer 4 is arranged. The first pressure point A and the starting point of the first insulating layer 4 can preferably be flush or substantially flush, with the distance between the two points preferably not exceeding 1 mm.

[0040] As in Fig. As shown in Figure 4, the concave and convex sides of the outer negative pole tab 5 are preferably each provided with a second insulating layer 6 to protect the outer negative pole tab 5. The film areas provided with the second insulating layer 6 are uncoated film areas.

[0041] In one embodiment, the first insulating layer 4 and the second insulating layer 6 can consist of different or the same materials.

[0042] In one embodiment, the first insulating layer 4 and / or the second insulating layer 6 of the present invention can consist of insulating tape. The insulating tape for the positive electrode or the insulating tape for the negative electrode of the present invention can be made of the same or different materials. Specifically, an insulating tape made of PI (polyimide) is selected for the first insulating layer 4. For the second insulating layer 6, an insulating tape made of PET (polyethylene terephthalate) is selected.

[0043] As in the Fig. 3 and Fig.As shown in Figure 4, the negative electrode 2 comprises a copper foil 23 and a region 21 made of negative electrode material, located on the concave and convex sides of the copper foil 23. A second hollow foil region 22 is arranged on the convex side at the end of the negative electrode 2, located on the outermost layer of the winding core and covering the area containing the predetermined arc length L.

[0044] In one embodiment, the length of the second hollow foil section 22 is more than twice the circumference of the outermost layer of the winding core; that is, the length of the hollow foil of the outermost layer exceeds one turn, thereby saving anode layer material while simultaneously maximizing the cell capacity. The end of the second hollow foil section 22 extends beyond the outer anode 5, providing it with some protection. That is, the outer anode 5 is connected to the anode foil 2 of the outermost layer of the winding core.

[0045] In a specific embodiment, the thickness of the cathode foil 1 (consisting of two layers of cathode material area 11 and one layer of aluminum foil 13) is 153 micrometers, with the thickness of the aluminum foil 13 being 15 micrometers. The thickness of the single-layer first insulating layer 4 is 32 micrometers. Since at the first pressure point A two layers of the first insulating layer 4 cover the cathode material area 11, the total thickness is 153 + 32 × 2 = 217 micrometers, i.e., the thickness at the first pressure point A has increased by 64 micrometers compared to the anode plate 1, while the total thickness of the empty foil area of ​​the aluminum foil 13 (i.e., the first empty foil area) is only 15 + 32 × 2 = 79 micrometers, even when two layers of the first insulating layer 4 are applied.At the same time, another sudden difference in thickness arises at this point in relation to the area of ​​the negative foil at the rear end 12 of the positive electrode 1 (near the outer negative tab 5).

[0046] In one embodiment, the length over which the two layers of the first insulating layer 4 (concave and convex side) partially cover the anode material area 11 along the winding length is 2 micrometers each.

[0047] In one embodiment, the length of the empty foil area of ​​the aluminium foil 13 of the anode plate 1 (i.e. the length of the first empty foil area) along the winding length is 6 micrometers.

[0048] In one embodiment, the thickness of the negative electrode 2 (consisting of two layers of a negative electrode material 21 and one layer of copper foil 23) is 159 micrometers, with the thickness of the copper foil 23 being 8 micrometers. The thickness of the second insulating layer 6 is 35 micrometers, and the thickness of the outer negative electrode tab 5 is 100 micrometers. It can be noted that the total thickness at the second pressing point B is 8 + 100 + 35 × 2 = 178 micrometers. The 178 micrometers represent a steep increase compared to the thickness of the copper foil 23 at the adjacent point (8 micrometers).

[0049] As described above, large expansion forces act on the first pressure point A and the second pressure point B, as well as the area between these two points, during the cell's charge and discharge cycles when the winding core expands. Compared to the outermost foil area of ​​the anode plate 2 between the first pressure point A and the second pressure point B, the first pressure point A and the second pressure point B come into strong contact with the steel casing first, resulting in high pressure. Subsequently, an expansion force F2 originating from the winding core acts on the outermost foil of the negative electrode 2 between the first and second pressure points, leading to an increase in the tensile force F1 acting on this foil section. If this tensile force F1 exceeds the tensile force threshold of the foil, a foil rupture occurs.

[0050] However, as the length of the outermost foil section of the negative electrode 2 between the first pressure point A and the second pressure point B increases, its tensile strength threshold also rises. In practical experiments, this is demonstrated by the fact that the failure rate of the foil decreases rapidly as soon as this length L reaches a certain value, i.e., as soon as the central angle α reaches a certain value.

[0051] It is understandable that at a central angle α > 180°, the film actually under pressure shifts to the other side of the film shown in the accompanying drawing, i.e., to the outermost film of the negative electrode 2 on the side corresponding to the central angle α. In the present invention, it was found that the shorter film section is more strongly affected. Therefore, for analysis, the shorter film from the outermost ring of the negative electrode 2 between the first pressure point A and the second pressure point B can simply be used, since the difference between the two is not significant.

[0052] In one embodiment, the cell can be designed such that the length L of the cell foil between the first squish point A and the second squish point B is fixed, with the diameter of the battery being D; by increasing L, the central angle α can be increased, where α = 360° × L / πD.

[0053] As shown in Table 1 below, in a specific embodiment 6 L = 32 µm and the battery diameter is 18 µm; in this embodiment a battery of type 18650 is used, resulting in α = 204°.

[0054] In one embodiment, the convex surface of the outermost negative electrode foil 2 consists entirely of hollow foil (i.e., the second hollow foil region 22), i.e., the entire convex surface of the negative electrode foil in contact with the steel housing consists of hollow foil, and no separating membrane 7 is provided between it and the steel housing; this arrangement can serve as a current conductor for the negative electrode.

[0055] In the present invention, theoretically α = 180° is most effective; in this case, the first pressure point A and the second pressure point B are on a line, and the films on the left and right sides are in essentially equivalent positions.

[0056] In one embodiment, the first pressure point A is located at the rear end of the anode material area 11. The reason that the rear end of the anode aluminum foil 13 was not chosen is that the rear end of the anode material area 11, especially after the application of double-layer insulating tape, is more prone to breakage.

[0057] In one embodiment, the second pressure point B is located in the middle of the outer anode tab 5. This choice serves to simplify the calculation and is also more scientifically sound.

[0058] In one embodiment, the convex side of the outermost negative electrode foil 2 consists entirely of a hollow foil (i.e., the second hollow foil region 22), with this part of the hollow foil being largely in direct contact with the metal casing of the battery. This can be understood as follows: Since the cylindrical side walls of the metal casing of the battery are directly connected to its base (the negative terminal) (formed from a single piece), this part of the casing is in direct contact with the metal casing of the battery and thus supports the current conduction of the negative electrode.Should the outermost negative electrode foil break—for example, the problem of the present invention is that the negative electrode foil breaks between the end of the positive electrode foil and the outer negative electrode tab (where the outer foil can also tear at the end of the positive electrode foil and at the outer negative electrode tab)—the outer negative tab 5 loses its ability to conduct electricity, so that the task of negative current conduction is completely taken over by the inner negative tab (if present) and the remaining outer foils of the negative electrode (the untorn parts). While the remaining outer foils of the negative electrode (the untorn parts) do possess some electrical conductivity, it is not very strong.Therefore, the problem of the anode foil breaking between the first pressing point A and the second pressing point B manifests itself directly in an increase in the cell's internal resistance, which differs significantly from a normal battery and ultimately leads to battery failure, so that the intended performance requirements cannot be met.

[0059] In order to verify the advantageous effect of the foil breakage protection design at the end of the coil according to this application, cyclic foil breakage tests were carried out with different embodiments; the test results are shown in Table 1 below. Table 1: Comparison of the results of the cyclic film breakage tests for different designs Number: Angle α (°) of the circular angle opposite the given arc length between the first and second pressing point and directed towards the center of the winding core Foil breakage rate after 250 revolutions Design 1: 120 1% Execution type 2: 150 0% Design 3: 170 0% Design 4: 180 0% Execution 5: 200 0% Design 6: 204 0% Design 7: 210 0% Design 8: 240 2% Comparison example 1: 90 6% Comparison example 2: 260 10%

[0060] For each of the scenarios mentioned above, 100 batteries were tested to determine the film breakage rate under realistic conditions. As shown in Table 1 and Fig. As shown in Figure 2, the film breakage rate is 6% at an angle α of 90°; as shown in Table 2, it is 10% at an angle α of 260°. This shows that an angle α that is too large or too small is undesirable.

[0061] Referring to embodiment 1 and embodiment 8, the film breakage rate is 1% at an α of 120° and 2% at an α of 240° (as in Fig. Figure 5 shows the internal resistance in milliohms on the Y-axis and the number of batteries on the X-axis. This demonstrates that the film breakage rate has decreased significantly.

[0062] Therefore, in one embodiment, α lies between 120° and 240°. The film breakage rate has already been reduced to a range of 2%.

[0063] Referring to embodiments 2 to 7, the film breakage rate at α from 150° to 210° (α = 150°, 170°, 180°, 200°, 204°, 210°) is already 0%, and no film breaks were observed in a test with 100 cells. Therefore, the advantageous value of the angle α, which corresponds to the predetermined arc length L relative to the center of the winding core, is preferably 150° to 210°.

[0064] As in Fig. 6 shown (the Y-axis in Fig. Figure 6 shows the internal resistance in milliohms, the x-axis the number of cells. The data in embodiment 6 (with a center angle α of 204°) show that no anomalies in the internal resistance were detected, indicating that no cells with foil breakage are present. Furthermore, Figure 6 shows that no anomalies in the internal resistance were detected, indicating that no cells with foil breakage are present. Fig. 6. that the resistance values ​​of the cells are more stable and uniform. Compared to Fig. 5 show the resistance values ​​of the cells in Fig.6 not only has the rate of foil breakage decreased further to almost 0%, but also the internal resistance of the batteries is more stable, proving that this structural improvement further increases the overall stability of the cell design.

[0065] Fig. 7 and Fig. Figure 8 shows two further specific embodiments, namely embodiment 9 and embodiment 10. It can be seen that the central angle α in Fig. 7 approximately 150° and in Fig. 8 is approximately 210°. The tests show that no film breaks occurred, and the film breakage rate was further verified by tests on 100 cells, with the results being 0% in each case.

[0066] Therefore, in a preferred embodiment, α is 150° to 210°; in this range we have found that the film breakage rate is practically 0%, and in the experiments hardly any film breaks caused by this problem could be detected, leading to a remarkable result.

[0067] In the optimal embodiment, the angle α between the predetermined arc length L and the center of the coil core is 180°. In this case, the first pressing point A and the second pressing point B are exactly opposite each other, thus minimizing the risk of foil breakage of the negative electrode 2. That is, the optimal value for α is 180°, which corresponds to the theoretically optimal value.

[0068] The structure described in this application for protection against film tears at the end of the winding core can be used in various fields, including portable electronic devices, electric vehicles, power tools, drones and energy storage systems.

[0069] Based on the same concept, this embodiment of the invention also provides a cylindrical battery comprising: a structure to prevent the foil from breaking at the rear end of the winding core, as described in one of the embodiments mentioned above.

[0070] It should be noted that the steel housing, the current-dissipating plate, and other parts of the cylindrical battery provided in this embodiment can be manufactured using any suitable, already known design. To present the technical solution provided in this embodiment clearly and concisely, the aforementioned parts will not be discussed further here. However, it is understood that this does not limit the scope of this embodiment.

[0071] In this embodiment, the embodiment of the cylindrical battery corresponds to the embodiment of the shatterproof foil structure at the end of the winding core; it can solve the technical problems solved by the embodiment of the shatterproof foil structure at the end of the winding core and achieves the corresponding technical effects of the embodiment of the shatterproof foil structure at the end of the winding core; the details are not discussed in this application.

[0072] It should be noted that the terms "first," "second," etc., used in this manual serve only to describe and distinguish similar objects; there is no chronological order between them, and they are not to be understood as an indication or suggestion of relative importance. Unless otherwise stated, "several" in this manual means two or more.

[0073] All numerical values ​​mentioned in this text include all values ​​between the lower and upper limits, increasing in increments of one unit, with a minimum interval of two units between each lower and each higher value. For example, when it is stated that the value of a component quantity or a process variable (e.g., temperature, pressure, time, etc.) is between 1 and 90, preferably between 20 and 80, and more preferably between 30 and 70, this is to clarify that values ​​such as 15 to 85, 22 to 68, 43 to 51, and 30 to 32 are also expressly included in this description. For values ​​less than 1, one unit is defined as 0.0001, 0.001, 0.01, or 0.1. These are merely examples for clarification; it can be assumed that all possible combinations of values ​​between the minimum and maximum values ​​are similarly expressly included in this description.

[0074] Unless otherwise specified, all ranges include the endpoints as well as all numbers between the endpoints. The terms "about" or "approximately" used in connection with a range refer to the two endpoints of the range. Therefore, "about 20 to 30" is intended to cover the range "about 20 to about 30" and includes at least the specified endpoints.

[0075] All disclosed articles and reference materials, including patent applications and publications, are hereby incorporated by reference for various purposes. The term "essentially consisting of...", used to describe a combination, is intended to include the identified elements, constituents, components, or steps, as well as other elements, constituents, components, or steps that do not substantially affect the fundamental novel features of that combination. The use of the terms "contains" or "comprises" here to describe the combination of elements, constituents, components, or steps also refers to embodiments that consist essentially of these elements, constituents, components, or steps. The use of the term "may" here is intended to clarify that any described features encompassed by "may" are optional.

[0076] Multiple elements, parts, components, or steps can be provided by a single integrated element, part, component, or step. Alternatively, a single integrated element, part, component, or step can be subdivided into multiple separate elements, parts, components, or conclusions. The use of the terms "a" or "an" to describe elements, parts, components, or steps is not intended to exclude other elements, parts, components, or steps.

[0077] It is understood that the foregoing description serves for illustration purposes and does not constitute a limitation. After reading the foregoing description, numerous embodiments and applications beyond the examples given will be obvious to the person skilled in the art. The scope of the present teaching should therefore not be determined on the basis of the foregoing description, but rather on the basis of the attached claims and the full scope of the equivalents of those claims. For the sake of completeness, all publications and references, including published patent applications and publications, are incorporated into this description by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims does not constitute a waiver of such subject matter and should not be interpreted as the inventor not considering such subject matter to be part of the disclosed subject matter of the invention.

Claims

A structure for preventing foil breakage at the end of a winding core of a cylindrical battery, characterized in that the structure for preventing foil breakage at the end of the winding core consists of a wound positive electrode and a wound negative electrode, wherein a separating membrane is arranged between the positive and the negative electrode; a first insulating layer is provided at the end of the positive electrode; areas for the positive electrode material are provided on both the concave and convex sides of the positive electrode; a portion of the first insulating layer covers the areas for the positive electrode material on the concave and convex sides at the end of the positive electrode; the starting point of the first insulating layer, which covers the areas for the positive electrode material, is defined as the first pressure point;The end piece of the negative pole has an uncoated film on which an outer pole attachment is arranged; the center point of the outer pole attachment in the circumferential direction is defined as the second pressing point; between the first and the second pressing point there is a predetermined arc length, wherein the angle of the circular angle that the predetermined arc length forms with the center of the winding core is 120° to 240°. A structure for preventing the film from breaking at the end of a winding core according to claim 1, characterized in that the angle of the circular angle formed by the predetermined arc length to the center of the winding core is 150° to 210°. A structure for preventing the film from breaking at the end of a winding core according to claim 2, characterized in that the angle between the predetermined arc length and the center of the coil is 180°. A structure for preventing the breakage of the film at the end of a winding core according to claim 1, characterized in that both the concave and the convex side of the outer negative connecting tab is provided with a second insulating layer. A structure for preventing the breakage of the film at the end of a winding core according to claim 4, characterized in that the first insulating layer and / or the second insulating layer consists of insulating tape. A structure for preventing breakage of the film at the end of a winding core according to claim 5, characterized in that the insulating tape of the first insulating layer consists of PI and the insulating tape of the second insulating layer consists of PET. A structure for preventing the foil from breaking at the end of a winding core according to claim 1, characterized in that a first foil space is provided at the end section of the positive electrode, wherein the positive electrode area is not arranged on either the concave or the convex side of the first foil space, and wherein the first insulating layer covers at least a part of the concave and a part of the convex side of the first foil space. A structure for preventing the breakage of the film at the end of a winding core according to claim 1, characterized in that a second film clearance is provided on the convex side of the end section of the negative electrode, wherein the second film clearance is located on the outermost layer of the winding roll and covers the area in which the intended arc length is located. A structure for preventing the film from breaking at the end of a winding core according to claim 8, characterized in that the length of the second film clearance is greater than the circumference of the outermost layer of the winding core. A cylindrical battery, characterized in that it comprises a structure for preventing breakage at the end of the winding core; wherein the structure for preventing breakage at the end of the winding core consists of a wound positive electrode and a wound negative electrode, with a separating membrane arranged between the positive and the negative electrode; wherein a first insulating layer is arranged at the end section of the positive electrode; wherein an area for the positive electrode material is provided on both the concave and the convex side of the positive electrode; the first insulating layer partially covers the anode material areas on the concave and the convex side at the end section of the anode foil; the starting point of the first insulating layer covering the anode material areas is defined as the first pressing point;The end piece of the negative electrode has an uncoated foil on which an outer negative electrode tab is arranged; the center point of the outer negative electrode tab in the circumferential direction is defined as the second pressing point; between the first and the second pressing point there is a predetermined arc length, the angle of the center point of this arc to the center point of the winding core being 120° to 240°.

Images