winding core

Abstract

The utility model belongs to battery processing technical field discloses a kind of roll core.The most inner circle's negative pole foil is close to the side of through hole without coating negative pole active material layer and forms single-sided empty foil area, negative pole piece has insulating layer on the outer edge of the side far from second blank foil and the corner position of winding start edge, the projection of insulating layer and single-sided empty foil area at least partially coincides and does not cover negative pole active material layer, insulating layer is towards the center of roll core, and cover negative pole active material layer more than one circle, insulating layer is used to prevent first blank foil puncture diaphragm and negative pole piece communication.The above-mentioned roll core, can avoid positive pole piece blank foil penetration diaphragm and negative pole piece contact, to avoid short circuit condition to occur further, simultaneously can improve the internal space utilization of roll core, improve the capacity density of roll core.

Description

Technical Field

[0001] This utility model relates to the field of battery processing technology, and in particular to a winding core. Background Technology

[0002] The all-tab cylindrical battery has attracted much attention due to its significantly improved overcurrent capability, reduced heat generation, and breakthrough in overcoming the limitations of cylindrical batteries. Leveling is a key process in the manufacturing of cylindrical all-tab batteries. During high-rate discharge, the internal resistance of the battery becomes a problem due to the large current flowing through it. Cylindrical batteries currently employ an all-tab design to reduce this internal resistance.

[0003] A cylindrical battery with multiple tabs consists of a core and two current collectors. The core is formed by winding a positive electrode, a separator, a negative electrode, and a separator together, stacked from the outside to the inside. A through hole is formed in the center of the core. The two ends of the core need to be flattened and then welded to the two current collectors. During the flattening process, a positioning pin is inserted into the through hole. After the blank foil on the top of the positive electrode is flattened, the blank foil of the positive electrode closer to the inside is prone to pressing against the positioning pin. Under a large external force, the blank foil of the positive electrode can easily extend into the through hole through the gap between the positioning pin and the wall of the through hole. There is a certain probability that the edge of the blank foil of the positive electrode will pierce the innermost separator and come into contact with the negative electrode, causing a short circuit and triggering a safety problem.

[0004] Furthermore, since the innermost ring of negative electrode sheet facing the through hole is a dead zone as the negative electrode active material layer does not participate in the chemical reaction, this layer thickness is completely wasted, resulting in a decrease in core capacity. Therefore, the existing design still has room for further improvement.

[0005] However, if the innermost ring of the negative electrode sheet facing the center of the core is left uncoated, resulting in an empty foil at the innermost ring of the negative electrode sheet, another problem arises. Since there is an active material layer on one side of the convex surface of the foil at the beginning of the negative electrode sheet, while the concave side is empty foil, the difference in tension between the two sides will cause the beginning of the negative electrode sheet to curl after being rolled by the roller press. This excessive inward curling of the innermost layer of the core will also affect the quality of the core.

[0006] Therefore, there is an urgent need to design a winding core to solve the above problems. Utility Model Content

[0007] One objective of this invention is to provide a core that prevents the blank foil of the positive electrode from penetrating the separator and contacting the negative electrode, thereby preventing short circuits. At the same time, it can improve the utilization of the internal space of the core and increase the capacity density of the core.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] The wound core is formed by winding together a positive electrode sheet, a separator, a negative electrode sheet, and a separator in sequence, with a through hole formed in the center of the wound core.

[0010] The positive electrode foil of the above-mentioned positive electrode sheet has a positive electrode active material layer and a first blank foil located at the axial end of the above-mentioned core; the negative electrode foil of the above-mentioned negative electrode sheet has a negative electrode active material layer and a second blank foil located at the axial end of the above-mentioned core.

[0011] At least the first blank foil is bent toward the center of the core and overlapped to form a flat surface;

[0012] The innermost ring of the negative electrode foil near the through hole is not coated with the negative electrode active material layer, forming a one-sided empty foil area. The negative electrode sheet has an insulating layer at the outer edge and corner position of the winding start edge on the side away from the second blank foil. The insulating layer at least partially overlaps with the projection of the one-sided empty foil area and does not cover the negative electrode active material layer. The insulating layer faces the center of the winding core. The insulating layer is used to prevent the first blank foil from piercing the diaphragm and communicating with the negative electrode sheet.

[0013] The length of the insulating layer extending from the starting end of the winding of the negative electrode sheet to the extension direction of the negative electrode sheet is L1, and the diameter of the inner circumference of the negative electrode sheet is D, where L1≥πD.

[0014] As an alternative, the negative electrode sheet located at the starting end of the winding and the starting end of the negative electrode active material layer on the inner side are spaced L4 apart in the circumferential direction, where πD≤L1≤πD+L4.

[0015] As an alternative, the insulating layer extends axially from the edge of the negative electrode near the first blank foil, with a height of L2, where L2 ≥ W1 - W2 - L3, forming a bending area on the outermost side of the first blank foil. W1 is the bending width of the bending area, W2 is the distance between the innermost positive electrode and the innermost diaphragm, and L3 is the axial distance between the flat surface and the edge of the negative electrode.

[0016] As an alternative, the aforementioned insulation layer can be insulating tape or an insulating ceramic layer.

[0017] As an alternative, the core is prepared by a flattening method, and the flat surface is a single, flat plane.

[0018] As an alternative, the core is prepared by a flattening method, and the flat surface also has grooves. The grooves are arranged radially and spaced along the inner and outer circumferences of the core on the flat surface, and the flat surface is divided into several independent welding areas by the grooves.

[0019] As an alternative, the diaphragm pre-wound with the aforementioned through-hole has at least two layers.

[0020] As an alternative, at the end furthest from the second blank foil, the edge of the negative electrode active material layer is flush with the edge of the negative electrode sheet.

[0021] As an alternative, the starting end of the winding of the negative electrode sheet is flush with the starting end of the winding of the negative electrode active material layer.

[0022] As an alternative, a third blank foil is provided between the winding start end of the negative electrode sheet and the winding start end of the negative electrode active material layer, and the width of the third blank foil is L3, where L3 < L1.

[0023] The beneficial effects of this utility model are as follows:

[0024] This invention provides a core in which an insulating layer is provided on the side of the negative electrode sheet facing the through hole. For example, after the top of the innermost blank foil abuts against the positioning pin, it is inserted into the gap between the positioning pin and the through hole. Its edge punctures the separator and then attaches to the insulating layer. The insulating layer acts as a protective layer, preventing the first blank foil from contacting the negative electrode sheet and causing a short circuit, thereby improving battery safety. Furthermore, by eliminating the innermost negative electrode active material layer of the innermost negative electrode sheet, the capacity inside the core is maximized, while simultaneously avoiding negative electrode... The waste of the active material layer coating, and the setting of an insulating layer in the single-sided empty foil area, solves the rolling tension problem generated in the single-sided empty foil area and solves the problem of inward curling. The setting of the insulating layer can effectively suppress this curling. Technically, this adhesive layer can be considered to replace the physical support role of the original negative electrode active material layer in terms of physical rigidity. In summary, the core of this embodiment can maximize its own capacity, and the negative electrode sheet will not curl. At the same time, it can prevent the positive electrode sheet from entering the through hole and contacting the innermost negative electrode sheet to cause a short circuit. Attached Figure Description

[0025] Figure 1 This is an exploded view of the flattened core and two current collectors welded together according to an embodiment of this utility model;

[0026] Figure 2 This is an exploded view of the flattened core and two current collectors welded together according to an embodiment of this utility model;

[0027] Figure 3 This is a layered diagram of the internal structure of the core provided in this embodiment of the utility model;

[0028] Figure 4 This is a schematic cross-section of the winding core provided in this embodiment of the utility model. Figure 1 ;

[0029] Figure 5 This is a schematic cross-section of the winding core provided in this embodiment of the utility model. Figure 2 ;

[0030] Figure 6 This is a stacking diagram (back side) of the positive and negative electrode sheets of the winding core at the starting end of winding when they are unwound in one embodiment of this utility model;

[0031] Figure 7 This is a stacking diagram (front view) of the positive electrode sheet, separator, negative electrode sheet, and separator at the starting end of winding when they are unfolded according to the embodiment of this utility model.

[0032] Figure 8 This is a schematic diagram of the partitioning of the flat surface of the core provided in this embodiment of the utility model;

[0033] Figure 9 This is a schematic diagram of the working principle of the electric screwdriver provided in this embodiment of the utility model;

[0034] Figure 10 This is a schematic diagram of the working principle of an electric vehicle provided in an embodiment of this utility model.

[0035] In the picture:

[0036] 10. Roll core;

[0037] 11. Flat surface; 111. Welding area; 1111. Weld line; 112. Groove;

[0038] 13. Positive electrode sheet; 131. Positive active material layer; 132. First blank foil; 133. Positive foil; 14. Negative electrode sheet; 141. Insulating layer; 142. Negative active material layer; 143. Second blank foil; 144. Third blank foil; 145. Negative foil; 146. Single-sided empty foil area; 15. Separator;

[0039] 16. Positive electrode flat surface; 17. Negative electrode flat surface; 18. Through hole;

[0040] 20. Current collector; 21. Positive current collector; 22. Negative current collector; 30. Winding start end;

[0041] 430. Battery pack; 431. Electric screwdriver; 432. Trigger switch; 433. Motor; 434. Shaft; 435. Motor control unit;

[0042] 600. Hybrid vehicle; 601. Engine; 602. Generator; 603. Electric drive power conversion device; 6041. First drive wheel; 6042. Second drive wheel; 6051. First wheel; 6052. Second wheel; 608. Battery; 609. Vehicle control device; 610. Various sensors; 611. Charging port. Detailed Implementation

[0043] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0044] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0045] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0046] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0047] Figure 1 The structure of a full-tab cylindrical battery according to one embodiment of the present invention (only the winding core 10 and two current collectors 20 are shown), see also Figure 3The core 10 is formed by winding together a positive electrode sheet 13, a separator 15, a negative electrode sheet 14, and a separator 15 in sequence, forming a cylindrical shape. The core 10 in this invention also has a battery casing, which is a cylindrical metal casing, preferably a steel or aluminum casing (casing not shown). The cylindrical battery assembled from the cells in this invention can be any type of cylindrical battery, preferably a 21700 or 18650 model cylindrical battery. Figure 3 As shown, in an optional embodiment, the positive electrode active material layer 131 covers most of the positive electrode foil 133, and the negative electrode active material layer 142 covers most of the negative electrode foil 145. In the unfolded state, blank foils are formed at both ends of the positive electrode sheet 13 and the negative electrode sheet 14 in the width direction (i.e., the positions where no active material is coated). Figure 3 As shown, taking the positive electrode sheet 13 as an example, a first blank foil 132 is formed at the position on the positive electrode foil 133 where the positive electrode active material layer 131 is not coated. Of course, see also... Figure 3 The portion of the negative electrode foil not coated with the negative electrode active material layer 142 forms a second blank foil 143. For example... Figure 3 As shown, when the core 10 is wound, the positive electrode active material layer 131 and the negative electrode active material layer 142 are staggered in the axial direction so that the first blank foil 132 and the second blank foil 143 are wound in opposite directions to form the core 10, and the upper and lower end faces are flattened into flat surfaces 11.

[0048] like Figure 3 As shown, the core 10 is housed in the battery casing while immersed in electrolyte. The first blank foil 132 can be a metal foil made of aluminum or aluminum alloy, and the second blank foil 143 can be a metal foil made of copper or copper alloy.

[0049] like Figure 1 As shown, in an optional embodiment, there is a through hole 18 on the central axis of the core 10, and a positioning pin (not shown in the figure) is inserted into the through hole 18. The positioning pin is used for welding the negative current collector 22 and the bottom of the battery casing.

[0050] like Figure 1 and Figure 3As shown, in an optional embodiment, the current collector 20 is divided into a positive current collector 21 and a negative current collector 22. The positive current collector 21 is welded to the flat surface 11 formed by the first blank foil 132. The positive current collector 21 can be a metal plate or sheet made of aluminum, aluminum alloy monomers, or composite materials. The negative current collector 22 is welded to the flat surface 11 formed by the second blank foil 143. The negative current collector 22 can be a metal plate or sheet made of nickel, nickel alloy, copper, copper alloy monomers, or composite materials. A hole is provided near the center of the positive current collector 21, and the position of the hole corresponds to the position of the through hole 18. The negative current collector 22 can be a single circular current collector or a circular current collector with a circular protrusion in the center. The center of the current collector 20 at the negative end is further welded to the bottom of the battery casing by an externally inserted positioning pin.

[0051] It is understandable that in this utility model Figures 1 to 8 These are merely schematic diagrams; the actual number of layers in the core 10 may vary. In an optional embodiment, the positive electrode active material layer 131 comprises any one or more positive electrode materials capable of lithium insertion and extraction. The positive electrode active material layer 131 may further comprise any one or more other materials such as a positive electrode binder and a positive electrode conductive agent. The positive electrode material can be lithium iron phosphate, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, or other existing lithium-ion battery positive electrode materials.

[0052] In an optional embodiment, the negative electrode material can be a carbon material, such as artificial graphite and natural graphite, or a graphite-based composite negative electrode material doped with a certain amount of silicon oxide or silicon carbon, as well as other existing lithium-ion battery negative electrode materials.

[0053] In an optional embodiment, the separator 15 can be a single-layer PP, single-layer PE, double-layer PP / PE, double-layer PP / PP, or triple-layer PP / PE / PP separator; the separator 15 can also be a porous membrane coated with ceramic particles, wherein the ceramic is preferably Al2O3 or boehmite; the separator 15 can also be other lithium-ion battery separator materials that are already available in the prior art.

[0054] In an optional embodiment, the electrolyte comprises a solvent and an electrolyte salt. In addition, the electrolyte may further comprise one or more of other materials, such as additives.

[0055] In an optional embodiment, the aforementioned solvent comprises any one or more non-aqueous solvents such as organic solvents. The non-aqueous solvent electrolyte is a so-called non-aqueous electrolyte, and the non-aqueous solvent may be, for example, cyclic carbonates, chain carbonates, lactones, chain carboxylic esters, nitriles (mononitriles), etc.

[0056] In an optional embodiment, the aforementioned electrolyte salt may comprise one or more of salts such as lithium salts. Alternatively, the electrolyte salt may also comprise salts other than lithium salts. These salts other than lithium salts may be, for example, light metal salts other than lithium.

[0057] In one embodiment, the battery casing is a metal casing, which can be a steel casing, an aluminum casing, or more preferably a steel casing.

[0058] In an optional embodiment, the aforementioned lithium salt is, for example, lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium tetraphenylborate (LiB(C6H5)4), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethanesulfonate (LiCF3SO3), lithium tetrachloroaluminate (LiAlCl4), lithium hexafluorosilicate (Li2SF6), lithium chloride (LiCl), and lithium bromide (LiBr). The aforementioned lithium salt can be any one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate; more preferably, it includes lithium hexafluorophosphate. The content of the electrolyte salt is not particularly limited, but preferably it is 0.3 mol / kg to 3 mol / kg relative to the solvent.

[0059] The preparation methods for forming the flat surface 11 are generally divided into flattening or pressing. The flattening method involves the flattening head of the flattening machine directly contacting the tab, and then, as the flattening head rotates and approaches the tab, it will roll and flatten the tab at the end of the wound cell 10. Figure 2 As shown, the core 10 prepared by the flattening method has flat surfaces at both ends that are a single, continuous plane. Flattening method ( Figure 1 Taking the positive electrode flat surface 16 as an example, the flat surface 11 is formed by bending and overlapping multiple layers of first blank foil 132 toward the central axis of the core 10 using a flattening device. The grooves 112 on the flat surface 11 are achieved by pressing down with pressure ribs. Figure 1 As shown, the first blank foil 132 and the second blank foil 143 are bent into a flat surface 11, with the bending direction from the outer periphery of the core 10 toward the through hole 18, and the adjacent blank foils of the positive electrode 13 or the negative electrode 14 are bent to overlap each other.

[0060] Regardless of whether the flat surface 11 is formed by kneading or pressing, during the leveling process, after the blank foil at the top of the positive electrode 13 is leveled, the first blank foil 132, which is closer to the inside, is prone to pressing against the positioning pin. Under a large external force, the first blank foil 132 can easily extend into the through hole 18 through the gap between the positioning pin and the wall of the through hole 18. There is a certain probability that the edge of the first blank foil 132 will pierce the innermost diaphragm 15 and come into contact with the negative electrode 14, causing a short circuit and triggering a safety problem. In addition, since the innermost ring of negative electrode 14 facing the through hole 18 does not participate in the chemical reaction and is considered a dead zone, the thickness of this layer is completely wasted, resulting in a decrease in the capacity of the core 10. Therefore, the existing design still has room for further improvement.

[0061] However, if the innermost ring of negative electrode sheet 14 facing the center of the core 10 is left uncoated, resulting in an empty foil at the innermost ring of the negative electrode sheet 14, another problem arises. Since there is an active material layer on one side of the convex surface of the foil at the beginning end of the negative electrode sheet 14, while the concave side is empty foil, the difference in tension on the two sides will cause the beginning end of the negative electrode sheet 14 to curl after being rolled by the roller press. This excessive inward curling of the innermost layer of the core 10 will also affect the quality of the core 10.

[0062] To address the aforementioned problems, this embodiment provides a core 10, such as... Figures 3-6 As shown, the innermost negative electrode foil 145 near the through hole 18 is not coated with the negative electrode active material layer 142, forming a one-sided empty foil area 146. The negative electrode sheet 14 has an insulating layer 141 at the outer edge and corner of the winding start edge on the side away from the second blank foil 143. The insulating layer 141 at least partially overlaps with the projection of the one-sided empty foil area 146 and partially covers the negative electrode active material layer 142. The insulating layer 141 faces the center of the core 10 and covers the negative electrode active material layer 142 more than one circle. The insulating layer 141 is used to prevent the first blank foil 132 from piercing the diaphragm 15 and communicating with the negative electrode sheet 14. The core 10, by providing the insulating layer 141 on the side of the negative electrode sheet 14 facing the through hole 18, such as when the top of the innermost first blank foil 132 abuts against the positioning pin and is inserted into the gap between the positioning pin and the through hole 18 (see...). Figure 3The separator 15 is punctured at its edge and then stuck to the insulating layer 141. The insulating layer 141 acts as a protective layer, preventing the first blank foil 132 from contacting the negative electrode 14 and causing a short circuit, thereby improving the battery's safety performance. On the other hand, by removing the innermost negative electrode active material layer 142 on the innermost negative electrode 14, the capacity inside the core 10 is maximized, while avoiding waste from coating the negative electrode active material layer 142. Meanwhile, the insulating layer 141 is placed in the single-sided blank foil area 146, solving the problem of… The rolling tension problem generated by the single-sided empty foil area 146 is solved, and the inward curling problem is solved. The setting of the insulating layer 141 can effectively suppress this curling. Technically, this adhesive layer can be considered to replace the physical support function of the original negative electrode active material layer 142 in terms of physical rigidity. In summary, the core 10 of this embodiment can maximize its own capacity, and the negative electrode sheet 14 will not curl. At the same time, it can prevent the positive electrode sheet 13 from entering the through hole 18 and contacting the innermost negative electrode sheet 14 to cause a short circuit.

[0063] In this embodiment, as Figure 6 As shown, the negative electrode active material layer 142 and the insulating layer 141 are adjacent to each other. In another embodiment, as... Figure 4 As shown, the negative electrode active material layer 142 and the insulating layer 141 have a certain distance in the extension direction of the core 10 when it is unfolded, which is not limited here.

[0064] In this case, at the end furthest from the second blank foil 143, the edge of the negative electrode active material layer 142 is flush with the edge of the negative electrode sheet 14.

[0065] See Figures 4-6 As shown, the end closest to the through hole 18 is defined as the winding start end 30. The negative electrode sheet 14 located at the winding start end 30 and the start end of the inner negative electrode active material layer 142 are spaced L4 apart in the circumferential direction, πD≤L1≤πD+L4. Thus, it can be ensured that the insulating layer 141 and the start end of the inner negative electrode active material layer 142 do not contact each other. Optionally, when the positive electrode 13, separator 15, negative electrode 14, and separator 15 are in a flattened state, the winding start end 30 is not flush. The winding start end 30 of the separator 15 inside the negative electrode 14 is forward of the winding start end 30 of the positive electrode 13, and the winding start end 30 of the separator 15 inside the negative electrode 14 is forward of the winding start end 30 of the negative electrode 14. The winding start ends 30 of the two separators 15 can be flush or staggered. More importantly, in order to ensure that the positive active material layer 131 of the positive electrode 13 falls entirely within the negative electrode 14 and to ensure that the coverage area of ​​both reaches the maximum, it is necessary to ensure that the winding start end 30 of the negative electrode 14 is forward of the winding start end 30 of the positive electrode 13.

[0066] The insulating layer 141 extends from the winding start end 30 of the negative electrode 14 in the direction of extension of the negative electrode 14. The length of the insulating layer 141 is L1, and the diameter of the through hole 18 is D, where L1 ≥ πD. That is, see [reference needed]. Figure 4 If L1 < πD, the insulating layer 141 does not form a complete circle of protection around the positioning pin, and there is a gap at the beginning and end. The first blank foil 132 may still pass through the diaphragm 15 through the gap and short-circuit with the negative electrode 14. Therefore, L1 ≥ πD is set to ensure that the protective area of ​​the insulating layer 141 is sufficient.

[0067] In a preferred embodiment, the starting end of the positive electrode 13 is positioned further back than the starting end of the inner negative electrode active material layer 142, as shown in the following figure. Figure 4 and Figure 5 In other words, the insulating layer 141 neither contacts the inner negative electrode active material layer 142 nor extends into the positive electrode 13, and will not affect the coverage area between the positive electrode 13 and the negative electrode 14. The starting end is at the rear, which ensures sufficient protection for the innermost negative electrode 14 without affecting the battery's capacity and interlayer thickness.

[0068] In an alternative embodiment, such as Figure 6 As shown, the starting end 30 of the negative electrode active material layer 142 is flush with the starting end 30 of the negative electrode sheet 14.

[0069] In an alternative embodiment, see Figure 3 and Figure 6 The insulating layer 141 extends axially from the edge of the negative electrode 14 near the first blank foil 132, and has a height of L2, where L2 ≥ W1 - W2 - L3. A bending region is formed on the outermost side of the first blank foil 132, where W1 is the bending width of the bending region, W2 is the distance between the innermost positive electrode 13 and the innermost separator 15, and L3 is the axial distance between the flat surface 11 and the edge of the negative electrode 14. Figures 3-5 To further explain the bending area, let's take flattening as an example only. The flattening process is similar. The blank foil of the positive electrode foil 133 extends axially along the core 10. A pressing fixture flattens the top of the blank foil of the positive electrode foil 133 (i.e., the first blank foil 132) to form a positive electrode flat surface 16 (the flat surface 11 at the other end of the core 10 is the negative electrode flat surface 17). The flattened portion is the bending portion, and the inward bending length of the bending portion is W1. It is understood that, see also... Figure 3For the innermost first blank foil 132, after bending the length of W1, the length of W2 is first cut off to the length that may be squeezed between the positioning pin and the side wall of the through hole 18. The remaining length is then cut down to a distance of L3 to reach the negative electrode 14. Considering the most extreme case, the farthest position that can be reached by this length going straight down is the lowest position of the insulating layer 141. If the bottom edge of the insulating layer 141 is higher than this position, the edge of the first blank foil 132 may pierce the diaphragm 15 inward and the insulating layer 141 may not be able to block it. Therefore, L2 is set to be greater than or equal to W1-W2-L3 to ensure that the first blank foil 132 and the negative electrode 14 are completely blocked in the axial direction of the core 10.

[0070] Among them, such as Figure 3 As shown, the first blank foil 132 and the second blank foil 143 are discussed separately for positive and negative electrodes due to the different flattening structures. The first blank foil 132 can be divided into a vertical region and a bending region L+W1, where the width of the vertical region is L and the width of the bending region is W1. Due to the design of the electrode structure, the negative electrode 14 will be larger than the positive electrode 13 in the width direction, and the entire negative electrode 14 will cover the positive electrode 13. Therefore, in the electrode width direction (i.e., the length direction of the core 10), the vertical region L can be further divided into an outer vertical region L5 and an inner vertical region L6, where L = L5 + L6, and the entire first blank foil 132 is L+W1. Generally, since the physical stiffness requirements of L5 and L6 are much greater than those of W1, in actual winding design, L6 is coated with ceramic slurry or insulating adhesive to increase its stiffness and resist bending. Simultaneously, its insulating coating effectively alleviates the internal shortness of the positive electrode 13 and negative electrode 14. For L5, depending on the needs, most or all of L5 is also coated with ceramic slurry or insulating adhesive to increase its stiffness and resist bending. The coatings on L5 and L6 are continuous coatings, and both can be made of the same material and coated simultaneously. This can be understood as the vertical region L having stronger physical stiffness than the bending region, ensuring that the vertical region L maintains a generally vertical orientation during flattening and preventing excessive interference with the negative electrode 14.

[0071] Through long-term practical exploration by technicians, it has been found that when L5 / L6 < 0.2, the ratio is too small and cannot effectively protect the negative electrode 14, while also affecting the alignment accuracy of the winding (this part often considers using adhesive coating). When L5 / L6 > 2, the ratio is too large, which affects the battery energy density, reducing the battery capacity by approximately 2.5%-5%. In an optional embodiment, a ratio of 0.2 ≤ L5 / L6 ≤ 2 is used. This setting achieves the effect of simultaneously protecting the negative electrode 14, ensuring the alignment accuracy of the winding, and preventing the battery energy density from being affected.

[0072] For the negative electrode, its structure is basically the same as that of the positive electrode. The main difference is that on the positive electrode side, the negative electrode sheet 14 is wider than the positive electrode sheet 13, while on the negative electrode side, this structure does not exist, and the entire negative electrode protrudes beyond the positive electrode sheet 13. Of course, the blank foil on the negative electrode side can also be divided into an L+W form (not shown in the figure), but L does not need to be further divided into L5 and L6. For the L part on the negative electrode side, we can also choose to coat it with ceramic slurry or insulating adhesive to increase the rigidity of L. However, considering that the L part of the negative electrode itself can meet the rigidity requirements of flattening, it is not necessary to coat it with ceramic slurry or insulating adhesive. The core reason is that the negative electrode side does not need to consider the problem of internal shorting caused by the contact between the negative electrode sheet 14 and the positive electrode. Therefore, the ceramic slurry or insulating adhesive coating on the negative electrode side is optional and can be selected according to actual needs.

[0073] It should be noted that in actual products, the vertical section L and the bending section can be directly connected, or they can be smoothly transitioned through a transition structure. In this invention, a direct connection is used.

[0074] In an optional embodiment, the insulating layer 141 is an insulating tape, meaning that the insulating layer 141 is directly adhered to the inner side of the negative electrode sheet 14 (specifically, the negative electrode active material layer 142), which is more convenient to operate. The insulating tape preferably used in this invention is PI tape, as well as other existing insulating tapes.

[0075] In an optional embodiment, the insulating layer 141 is formed by coating an insulating ceramic layer, which is not limited herein. The insulating ceramic layer is preferably a mixed coating of Al2O3 / boehmite and PVDF, or other existing insulating ceramic layers.

[0076] In another alternative embodiment, such as Figures 3-5 As shown, the innermost separator 15 can be provided in at least two layers, which can further increase the insulation thickness and improve the puncture resistance. In principle, due to the presence of the insulating layer 141 of this invention, the innermost separator 15 can be a single layer, or even no separator 15 can be provided, all of which can prevent internal short circuits in the battery. However, in order to achieve a double protection effect, the separator 15 of this invention is provided in two or more layers. At the very least, the insulating layer 141 of this invention can effectively reduce the number of separator 15 layers required.

[0077] In an optional embodiment, such as Figure 8As shown, when the core is prepared by a flattening method, grooves 112 are formed on the flat surface 11. The grooves 112 are arranged radially and spaced along the inner and outer circumferences of the core on the flat surface 11, dividing the flat surface 11 into several independent welding areas 111. The grooves 112 can absorb the folds generated when the multiple layers of first blank foil 132 or multiple layers of second blank foil 143 are stacked and pressed inward, thereby reducing the flatness of the flat surface 11 and improving the welding stability with the current collector 20.

[0078] Combination Figure 8 The method for obtaining the flatness of flat surface 11 is explained, such as... Figure 8 As shown, in the experiment, a 3D profilometer was used to test the flatness of the flat surface 11 of the core 10. The plane to be measured was selected, and the machine identified the highest and lowest points of the selected area and automatically calculated the difference between the high and low points, i.e., the flatness.

[0079] The formula for calculating flatness is as follows:

[0080] F = H1 - H2;

[0081] Where F is the flatness of the test area of ​​the flat surface 11 of the core 10, H1 is the height of the highest point of the test area of ​​the flat surface 11 of the core 10, and H2 is the height of the lowest point of the test area of ​​the flat surface 11 of the core 10. Figure 7 The shaded area represents the eight overall planar regions measured. In one specific embodiment, the flatness measured by this invention is the flatness of the entire cell end face (including the eight welding areas).

[0082] For example, Figure 8 The shaded area represents the eight welding areas 111 that were measured. The welding areas 111 are used to weld with the corresponding current collectors 20. Those skilled in the art can measure the flatness of the entire flat surface 11 as needed, or measure the flatness of each welding area 111 individually.

[0083] In an alternative embodiment, such as Figure 8 As shown, the number M of grooves 112 can generally be either symmetrical or capable of evenly dividing the circumference. Generally, the number of M should be greater than or equal to 4. M can be selected as 4, 5, 6, 8, 9, 10, 12, etc. All point values ​​or ranges greater than or equal to 4 and less than or equal to 12 are within the protection scope of this optional embodiment. Specifically, based on the size of commonly used core 10, the number M in this optional embodiment can be selected as 6 or 8.

[0084] In an alternative embodiment, such as Figure 8As shown, the grooves 112 can be evenly distributed across the entire circumference of the flat surface 11, with equal intervals between them. This ensures the uniformity of the overall strength and hardness of the flat surface 11, as well as its overall flatness, guaranteeing a stable welding effect between the flat surface 11 and the current collector 20. Of course, in other optional embodiments, it is possible that certain areas may not have grooves 112, or that the grooves 112 may be arranged in a non-uniformly spaced manner. All different arrangements of the grooves 112 are within the protection scope of this application.

[0085] In an alternative embodiment, such as Figure 8 As shown, the arrangement of the slots 112 should extend from the inner periphery to the outer periphery of the core 10 and penetrate the entire core 10. This design divides the flat surface 11 into several independent fan-shaped areas, which are used for welding with the current collector 20. These fan-shaped areas are referred to as welding areas 111. These welding areas 111 can be identical fan-shaped areas, which are independent and not connected to each other. For example, in this embodiment, a preferred solution is to divide the area into eight equal-area, fan-shaped welding areas 111 by eight slots 112 spaced at the same angle of 45°.

[0086] Optionally, such as Figure 8 As shown, the welding area 111 and the corresponding position of the current collector 20 are welded by a welding line 1111. The welding line 1111 is a straight spiral welding line, which is simple in shape and convenient for welding. It should be noted that, since the flat surface obtained by this utility model has high flatness, the choice of welding line is not limited to a straight spiral welding line; any existing welding line can be used.

[0087] In an alternative embodiment, such as Figure 8 As shown, several welding lines 1111 are radially distributed around the center of the core 10. This arrangement improves the uniformity of welding between the flat surface 11 and the corresponding current collector 20. In this embodiment, as... Figure 8 As shown, the number of welding lines 1111 and grooves 112 is set to eight. In other embodiments, it can be understood that the present invention does not require all welding areas 111 to be welded, and the number of welding lines 1111 can be less than the number of welding areas 111, and can be 3, 4, 5, 6 or 7, etc., which are not limited here.

[0088] This winding core is used in a multi-tab cylindrical battery, which includes the aforementioned winding core 10 and two current collectors 20. The two current collectors 20 and two flat surfaces 11 are correspondingly arranged and connected by welding. By using the aforementioned winding core 10, this multi-tab cylindrical battery can reduce the probability of short circuits and improve the battery's safety performance.

[0089] Optionally, the all-tab cylindrical battery provided in this embodiment can be applied to an electrical device, which includes the all-tab cylindrical battery and an electrical component. The all-tab cylindrical battery is used to supply power to the electrical component. By using the all-tab cylindrical battery, the electrical device improves its electrical safety.

[0090] In one optional embodiment, the electrical component may be an electronic device. Examples include notebook computers, smartphones, tablets, PDAs (portable information terminals), mobile phones, wearable devices, cordless handsets, camcorders, digital cameras, e-books, electronic dictionaries, music players, radios, headphones, game consoles, navigation systems, memory cards, pacemakers, hearing aids, power tools, electric shavers, refrigerators, air conditioners, televisions, stereos, water heaters, microwave ovens, dishwashers, washing machines, dryers, lighting equipment, toys, medical devices, robots, load conditioners, signal controllers, etc.

[0091] Reference Figure 9 This section briefly describes an example of an electric tool, such as an electric screwdriver, to which this invention can be applied. The electric screwdriver 431 houses a motor 433, such as a DC motor, within its main body. The rotation of the motor 433 is transmitted to a shaft 434, which screws the screw into the workpiece. A user-operated trigger switch 432 is provided on the electric screwdriver 431.

[0092] The lower frame of the handle of the electric screwdriver 431 houses a battery pack 430 (which may consist of multiple omni-tab cylindrical batteries) and a motor control unit 435. The motor control unit 435 controls the motor 433. Other parts of the electric screwdriver 431 besides the motor 433 can also be controlled by the motor control unit 435. Although not shown, the battery pack 430 and the electric screwdriver 431 are engaged by their respective engaging components. As described later, both the battery pack 430 and the motor control unit 435 are equipped with microcomputers. Battery power is supplied to the motor control unit 435 from the battery pack 430, and information about the battery pack 430 is communicated between the microcomputers of both units.

[0093] The battery pack 430 is removable from, for example, the electric screwdriver 431. The battery pack 430 may also be built into the electric screwdriver 431. The battery pack 430 is installed in a charging device during charging. It should be noted that, when the battery pack 430 is installed in the electric screwdriver 431, a portion of the battery pack 430 may protrude from the exterior of the electric screwdriver 431, allowing the user to visually identify the exposed portion. For example, an LED may be installed on the exposed portion of the battery pack 430, allowing the user to confirm the LED's illumination and deactivation.

[0094] The motor control unit 435 controls, for example, the rotation, stopping, and rotation direction of the motor 433. Furthermore, it cuts off the power supply to the load in case of over-discharge. A trigger switch 432 is inserted between the motor 433 and the motor control unit 435. When the user presses the trigger switch 432, the motor 433 is powered and rotates. When the user returns the trigger switch 432 to its original position, the rotation of the motor 433 stops.

[0095] In one optional embodiment, the electrical component may be an electric vehicle. Examples of electric vehicles include railway vehicles, golf carts, electric trolleys, and electric vehicles (including hybrid vehicles), which can be used as a power source for their propulsion or as an auxiliary power source. Examples of energy storage devices include power storage devices for buildings such as residences or for power generation equipment.

[0096] Reference Figure 10 This section describes an example of applying this invention to an energy storage system for electric vehicles. Figure 10 This diagram schematically illustrates an example of the structure of a hybrid vehicle employing the series hybrid system of this invention. A series hybrid system is a vehicle that uses electricity generated by a generator driven by an engine or electricity temporarily stored in a battery to drive the vehicle.

[0097] The hybrid vehicle 600 includes an engine 601, a generator 602, an electric drive power conversion device 603, a first drive wheel 6041, a second drive wheel 6042, a first wheel 6051, a second wheel 6052, a battery 608, a vehicle control device 609, various sensors 610, and a charging port 611. The battery pack 430 of this invention is used in the battery 608.

[0098] The hybrid vehicle 600 operates using an electric drive power conversion device 603 as its power source. One example of the electric drive power conversion device 603 is a motor. Powered by the battery 608, the electric drive power conversion device 603 transmits its rotational force to the first drive wheel 6041 and the second drive wheel 6042. It should be noted that the electric drive power conversion device 603 can be used with either an AC motor or a DC motor by employing DC-AC or AC-DC conversion where necessary. Various sensors 610 control the engine speed or the opening of a throttle valve (not shown) via the vehicle control unit 609. These sensors 610 include speed sensors, acceleration sensors, engine speed sensors, etc.

[0099] The rotational force of the engine 601 is transmitted to the generator 602, through which the electricity generated by the generator 602 can be stored in the battery 608.

[0100] When the hybrid vehicle 600 is decelerated by a braking mechanism (not shown), the resistance during deceleration is applied as a rotational force to the electric drive force conversion device 603, and the regenerative power generated by the electric drive force conversion device 603 through this rotational force is stored in the battery 608.

[0101] The battery 608 can also receive power from the external power source by connecting to the external power source of the hybrid vehicle 600, and store the received power by using the charging port 611 as an input port.

[0102] Although not illustrated, the device could also include an information processing unit for vehicle control based on information related to the secondary battery. Examples of such an information processing unit include one that displays the remaining battery level based on information related to the remaining battery level.

[0103] It should be noted that the above description uses a series hybrid vehicle as an example, which uses electricity generated by a generator driven by an engine or electricity temporarily stored in a battery to run on a motor. However, this invention can also be effectively applied to parallel hybrid vehicles that use both the engine and motor outputs as drive sources and appropriately switch between three modes: running on the engine alone, running on the motor alone, and running on both the engine and motor. Furthermore, this invention can also be effectively applied to so-called electric vehicles that do not use an engine and run solely on the drive motor.

[0104] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A wound core, wherein the wound core is formed by winding together a positive electrode sheet (13), a separator (15), a negative electrode sheet (14), and a separator (15) stacked sequentially, and a through hole (18) is formed in the center of the wound core, characterized in that: The positive electrode sheet (13) has a positive electrode active material layer (131) and a first blank foil (132) located at the axial end of the core on the positive electrode foil (133); the negative electrode sheet (14) has a negative electrode active material layer (142) and a second blank foil (143) located at the axial end of the core on the negative electrode foil (145); At least the first blank foil (132) is bent toward the center of the core and overlapped to form a flat surface (11); The innermost negative electrode foil (145) near the through hole (18) is not coated with the negative electrode active material layer (142), forming a one-sided empty foil area (146). The negative electrode sheet (14) has an insulating layer (141) at the outer edge and the corner position of the starting edge of the winding on the side away from the second blank foil (143). The insulating layer (141) at least partially overlaps with the projection of the one-sided empty foil area (146) and does not cover the negative electrode active material layer (142). The insulating layer (141) faces the center of the core. The insulating layer (141) is used to prevent the first blank foil (132) from piercing the diaphragm (15) and communicating with the negative electrode sheet (14). The length of the insulating layer (141) extending from the winding start end (30) of the negative electrode (14) to the extension direction of the negative electrode (14) is L1, and the diameter of the inner circumference of the negative electrode (14) is D, where L1≥πD.

2. The winding core according to claim 1, characterized in that, The negative electrode sheet (14) located at the winding start end (30) and the start end of the negative electrode active material layer (142) on the inner side are spaced L4 in the circumferential direction, where πD≤L1≤πD+L4.

3. The winding core according to claim 1, characterized in that, The insulating layer (141) extends axially from the edge of the negative electrode (14) near the first blank foil (132) and has a height of L2, where L2 ≥ W1-W2-L3. A bending area is formed on the outermost side of the first blank foil (132), where W1 is the bending width of the bending area, W2 is the distance between the innermost positive electrode (13) and the innermost separator (15), and L3 is the axial distance between the flat surface (11) and the edge of the negative electrode (14).

4. The winding core according to claim 1, characterized in that, The insulating layer (141) is an insulating tape or an insulating ceramic layer.

5. The winding core according to any one of claims 1-4, characterized in that, The core is prepared by a flattening method, and the flat surface (11) is a single plane.

6. The winding core according to any one of claims 1-4, characterized in that, The core is prepared by a flattening method, and the flat surface (11) also has grooves (112). The grooves (112) are arranged radially along the inner and outer peripheries of the core on the flat surface (11). The flat surface (11) is divided into several independent welding areas (111) by the grooves (112).

7. The winding core according to any one of claims 1-4, characterized in that, The diaphragm (15) pre-wound by the through hole (18) has at least two layers.

8. The winding core according to any one of claims 1-4, characterized in that, At the end furthest from the second blank foil (143), the edge of the negative electrode active material layer (142) is flush with the edge of the negative electrode sheet (14).

9. The winding core according to any one of claims 1-4, characterized in that, The starting end (30) of the negative electrode sheet (14) is flush with the starting end (30) of the negative electrode active material layer (142).

10. The winding core according to any one of claims 1-4, characterized in that, There is also a third blank foil (144) between the winding start end (30) of the negative electrode sheet (14) and the winding start end (30) of the negative electrode active material layer (142), and the width of the third blank foil (144) is L3, where L3 < L1.

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