Jelly roll
Patent Information
- Application Number
- PCT/CN2026/079465
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-25
- Filing Date
- 2026-02-14
- Publication Date
- 2026-09-03
Smart Images
Figure CN2026079465_03092026_PF_FP_ABST
Abstract
Description
Roll core Technical Field
[0001] This invention relates to the field of battery processing technology, and more particularly 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, and a negative electrode, stacked sequentially from the outside to the inside, to create a through hole 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. Because 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] Therefore, there is an urgent need to design a winding core to solve the above problems. Summary of the Invention
[0005] The purpose 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 and improving battery safety.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] The core is formed by winding a positive electrode sheet, a separator, a negative electrode sheet, and a separator together in sequence, so as to form a through hole in the center of the core.
[0008] The positive electrode foil of the aforementioned positive electrode sheet has a positive electrode active material layer and a first blank foil located at the axial end of the aforementioned core, and the first blank foil is joined to the positive electrode current collector at one end of the aforementioned core; the negative electrode foil of the aforementioned negative electrode sheet has a negative electrode active material layer and a second blank foil located at the axial end of the aforementioned core, and the second blank foil is joined to the negative electrode current collector at the other end of the aforementioned core.
[0009] At least the first blank foil is bent toward the center of the core and overlapped to form a flat surface;
[0010] The aforementioned 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 blank foil of the aforementioned negative electrode sheet. The insulating layer at least partially overlaps with the projection of the aforementioned negative electrode active material layer. The insulating layer faces the center of the aforementioned core. The insulating layer is used to prevent the aforementioned first blank foil from piercing the aforementioned diaphragm and communicating with the aforementioned negative electrode sheet.
[0011] 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.
[0012] As an alternative, the negative electrode at the starting end of the winding is wound inward by a predetermined distance L4 more than the positive electrode, where πD≤L1≤πD+L4.
[0013] 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 separator, and L3 is the axial distance between the flat surface and the edge of the negative electrode.
[0014] As an alternative, the aforementioned insulation layer can be insulating tape or an insulating ceramic layer.
[0015] As an alternative, the core is prepared by a flattening method, and the flat surface is a single, flat plane.
[0016] 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.
[0017] As an alternative, the diaphragm with the aforementioned through holes pre-wound has at least two layers.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] The beneficial effects of this invention are as follows:
[0022] 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, the top of the innermost first blank foil abuts against the positioning pin and is inserted into the gap between the positioning pin and the through hole. Its edge punctures the separator and is stuck to the insulating layer. The insulating layer and the negative electrode sheet play a protective role, preventing the first blank foil from contacting the negative electrode sheet and causing a short circuit, thereby improving the safety performance of the battery. Attached Figure Description
[0023] Figure 1 is an exploded view of the flattened core and two current collectors welded together according to an embodiment of the present invention;
[0024] Figure 2 is an exploded view of the flattened core and the welding of two current collectors provided in an embodiment of the present invention;
[0025] Figure 3 is a layered diagram of the inside of the core provided in an embodiment of the present invention;
[0026] Figure 4 is a schematic cross-sectional view of the winding core provided in an embodiment of the present invention;
[0027] Figure 5 is a stacking diagram (back side) of the positive and negative electrode sheets of the core at the winding start end when they are unwound in one embodiment of the present invention.
[0028] Figure 6 is a stacking diagram (front) of the core positive electrode sheet, separator, negative electrode sheet, and separator at the winding start end when they are unwound according to an embodiment of the present invention.
[0029] Figure 7 is a stacking diagram (back side) of the positive and negative electrode sheets of the core at the winding start end when they are unwound in another embodiment of the present invention.
[0030] Figure 8 is a schematic diagram of the partitioning of the flat surface of the core provided in an embodiment of the present invention;
[0031] Figure 9 is a schematic diagram of the working principle of the electric screwdriver provided in an embodiment of the present invention;
[0032] Figure 10 is a schematic diagram of the working principle of the electric vehicle provided in an embodiment of the present invention.
[0033] In the picture:
[0034] 10. Roll core;
[0035] 11. Flat surface; 111. Welding area; 1111. Weld line; 112. Groove;
[0036] 13. Positive electrode sheet; 131. Positive electrode active material layer; 132. First blank foil; 14. Negative electrode sheet; 141. Insulating layer; 142. Negative electrode active material layer; 143. Second blank foil; 144. Third blank foil; 15. Separator;
[0037] 16. Positive electrode flat surface; 17. Negative electrode flat surface; 18. Through hole;
[0038] 20. Current collector; 21. Positive current collector; 22. Negative current collector; 30. Winding start end;
[0039] 430. Battery pack; 431. Electric screwdriver; 432. Trigger switch; 433. Motor; 434. Shaft; 435. Motor control unit;
[0040] 600. Hybrid vehicle; 601. Engine; 602. Generator; 603. Electric drive power conversion device; 604a. First drive wheel; 604b. Second drive wheel; 605a. First wheel; 605b. Second wheel; 608. Battery; 609. Vehicle control device; 610. Various sensors; 611. Charging port. Detailed Implementation
[0041] 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 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, and not all of the structures.
[0042] In the description of this invention, 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 invention based on the specific circumstances.
[0043] 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.
[0044] 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 the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.
[0045] Figure 1 shows the structure of a cylindrical battery with all tabs according to an embodiment of the present invention (only the core 10 and two current collectors 20 are shown). Referring to Figure 3, the core 10 is formed by winding a positive electrode 13, a separator 15, a negative electrode 14, and a separator 15 sequentially stacked, 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. As shown in Figure 3, in an optional embodiment, the positive electrode active material layer 131 covers most of the positive electrode foil, and the negative electrode active material layer 142 covers most of the negative electrode foil. In the unfolded state, the positive electrode 13 and the negative electrode 14 form the aforementioned blank foil at both ends in the width direction (i.e., the positions where no active material is coated). As shown in Figure 3, taking the positive electrode sheet 13 as an example, the position on the positive electrode foil where the positive electrode active material layer 131 is not coated forms the first blank foil 132. Similarly, referring to Figure 3, the portion of the negative electrode foil where the negative electrode active material is not coated forms the second blank foil 143. As shown in Figure 3, 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.
[0046] As shown in Figure 3, 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.
[0047] As shown in Figure 1, in an optional embodiment, there is a through hole 18 on the central axis of the core 10. The through hole 18 is used to insert a positioning pin (not shown in the figure). The positioning pin is used for welding the negative electrode current collector 22 and the bottom of the battery casing.
[0048] As shown in Figures 1 and 3, 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 positive blank foil. 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 negative blank foil. The negative current collector 22 can be a metal plate or sheet made of nickel, nickel alloy, copper, or copper alloy monomers or composite materials. A hole is formed 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.
[0049] It is understood that Figures 1 to 8 in this invention are merely schematic diagrams; for example, the actual number of layers in the core 10 is subject to actual conditions. 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.
[0050] 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.
[0051] In an optional embodiment, the separator 15 may 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 may also be a porous membrane coated with ceramic particles, wherein the ceramic is preferably Al2O3 or boehmite; the separator 15 may also be other lithium-ion battery separator materials that are already available in the prior art.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] The preparation methods for forming the flat surface 11 are generally divided into flattening and pressing. The flattening method involves the flattening head of a flattening machine directly contacting the tab. As the flattening head rotates and approaches the tab, it flattens the tab at the end of the wound cell, as shown in Figure 2. The flattening method produces a core with flat surfaces at both ends that are a single, continuous plane. The pressing method (Figure 1), taking the positive electrode flat surface 16 as an example, involves bending and overlapping multiple layers of first blank foil 132 towards the central axis of the core 10 using a pressing device to form the aforementioned flat surface 11. The grooves on the flat surface 11 are achieved by pressing down with pressure ribs. As shown in Figure 1, the positive and negative blank foils are bent into the flat surface 11, with the bending direction from the outer periphery of the core 10 towards the through hole 18. The adjacent blank foils of the positive electrode 13 or negative electrode 14 are bent and overlapped.
[0058] 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 likely to press against the positioning pin. Under the action of a large external force, the first blank foil 132 is likely to 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.
[0059] To address the aforementioned issues, this embodiment provides a winding core, as shown in Figures 3, 4, and 5. The negative electrode sheet 14 has an insulating layer 141 at the outer edge of the side away from the blank foil (i.e., the second blank foil 143) of the negative electrode sheet 13 and at the corner of the winding start edge. The insulating layer 141 at least partially overlaps with the projection of the negative electrode active material layer 142. The insulating layer 142 faces the center of the winding core and covers the negative electrode active material layer 142 more than one ring. 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 aforementioned core 10 has an insulating layer 141 on one side of the negative electrode sheet 14 facing the through hole 18. For example, 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 3). Its edge punctures the separator 15 and sticks to the insulating layer 141. The insulating layer 141 plays a protective role, preventing the first blank foil 132 from contacting the negative electrode sheet 14 and causing a short circuit, thereby improving the safety performance of the battery.
[0060] 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.
[0061] Referring to Figures 3 and 4-6, the end closest to the through hole 18 is defined as the winding start end 30. The negative electrode 14 located at the winding start end 30 is wound inward by a predetermined distance L4 more than the positive electrode 13. It can be understood that when the positive electrode 13, the separator 15, the negative electrode 14, and the separator 15 are in the 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 closer to the winding start end 30 of the positive electrode 13. Previously, the starting end 30 of the winding of the separator 15 inside the negative electrode 14 was forward of the starting end 30 of the winding of the negative electrode 14. The starting ends 30 of the winding of the two separators 15 could be flush or staggered. More importantly, in order to ensure that the positive active material layer 131 of the positive electrode 13 falls entirely inside the negative electrode 14 and to ensure that the coverage area of the two reaches the maximum, it is necessary to ensure that the starting end 30 of the winding of the negative electrode 14 is forward of the starting end 30 of the winding of the positive electrode 13.
[0062] 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, referring to 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.
[0063] In a preferred embodiment, L1≤πD+L4. As shown in Figure 4, if the length of the insulating layer 141 is too long, it may extend into the space between the second ring of negative electrode 14 and the first ring of positive electrode 13. This would affect the ion or electron exchange rate between the positive electrode 13 and the negative electrode 14, thus affecting the battery's capacity and interlayer thickness. Therefore, setting L1≤πD+L4 ensures sufficient protection for the innermost negative electrode 14 without affecting the battery's capacity and interlayer thickness.
[0064] In an optional embodiment, as shown in FIG5, the winding start end 30 of the negative electrode active material layer 142 is flush with the winding start end 30 of the negative electrode sheet 14.
[0065] In another embodiment, as shown in FIG7, a third blank foil 144 is provided between the winding start end 30 of the negative electrode 14 and the winding start end 30 of the negative electrode 14, and the width of the third blank foil 144 is L3, where L3 < L1.
[0066] In an optional embodiment, referring to Figures 3 and 5, the insulating layer 141 extends axially from the edge of the negative electrode 14 near the first blank foil 132, with a height of L2, where L2 ≥ W - 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. The bending area is further explained with reference to Figures 3 and 4. Flattening is used as an example only. The flattening situation is similar. The blank foil of the positive electrode extends axially along the core 10. The top of the blank foil of the positive electrode (i.e., the first blank foil 132) is flattened by the pressing tool (part of the first blank foil 132) to form the 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 part is the bending part, and the length of the inward bending of the bending part is W1. It is understandable that, referring to Figure 3, for the innermost first blank foil 132, after the length of W1 is bent, 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.
[0067] As shown in Figure 3, the first blank foil 132 and the second blank foil 143 are discussed separately for positive and negative electrodes due to their different flattening structures. The first blank foil 132 can be divided into a vertical region and a bending region L+W, where the width of the vertical region is L and the width of the bending region is W. 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. The entire first blank foil 132 is L+W. Generally, since the physical stiffness requirements of L5 and L6 are much greater than those of the W section, in actual coil 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, preventing excessive interference with the negative electrode 14.
[0068] Through long-term practical exploration by technicians, it has been found that when L5 / L6 < 0.2, it cannot effectively protect the negative electrode 14 and also affects the alignment accuracy of the winding (this part often considers using adhesive coating). When L5 / L6 > 2, the battery energy density will be affected, and the battery capacity will decrease by about 2.5%-5%. In an optional embodiment, 0.2 ≤ L5 / L6 ≤ 2 is used. This setting can simultaneously protect the negative electrode 14, ensure the alignment accuracy of the winding, and prevent the battery energy density from being affected.
[0069] 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.
[0070] It should be noted that in actual products, the vertical section L and the bending section can be directly connected, or a smooth transition can be achieved through a transition structure. In this invention, a direct connection is used.
[0071] In an optional embodiment, the insulating layer 141 is an insulating tape, meaning that the insulating layer 141 is directly adhered to one side of the negative electrode, which is more convenient to operate. The insulating tape is preferably PI tape, or other existing insulating tapes.
[0072] 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.
[0073] In another optional embodiment, as shown in Figures 3 and 4, the innermost separator 15 can be provided with 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 the present invention, the innermost separator 15 can be a single layer, or even without a separator, to prevent internal short circuits in the battery. However, to achieve a double protection effect, the separator of the present invention is provided with two or more layers. At the very least, the insulating layer 141 of the present invention can effectively reduce the number of separator layers required.
[0074] In an optional embodiment, as shown in FIG8, when the core is prepared by a flattening method, grooves 112 are formed on the flat surface 11. The grooves 112 are radially spaced along the inner and outer peripheries of the core on the flat surface 11, dividing the flat surface 11 into several independent welding areas 111. This allows for the absorption of material from wrinkles generated during the inward stacking and pressing of multiple layers of first blank foil 132 or multiple layers of second blank foil 143, thereby reducing the flatness of the flat surface 11 and improving the welding stability with the current collector 20.
[0075] The flatness of the flat surface 11 is obtained by referring to Figure 8. As shown in Figure 8, in the experiment, a 3D profilometer is used to test the flatness of the flat surface 11 of the core 10. The plane to be measured is selected, the machine identifies the highest and lowest points of the selected area, and automatically calculates the difference between the high and low points, which is the flatness.
[0076] The formula for calculating flatness is as follows:
[0077] F = H1 - H2;
[0078] Wherein, F represents the flatness of the test area of the flat surface 11 of the core 10, H1 represents the height of the highest point of the test area of the flat surface 11 of the core 10, and H2 represents the height of the lowest point of the test area of the flat surface 11 of the core 10. The shaded area in Figure 6 represents the eight overall planar areas measured. In a specific embodiment, the flatness measured by the present invention is the flatness of the entire end face of the battery cell (including the eight welding areas).
[0079] For example, the shaded area in Figure 8 represents the eight welded areas 111 that were measured. The welded 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 welded area 111 individually.
[0080] In an optional embodiment, as shown in FIG8, the number M of grooves 112 can generally be either a symmetrical number or a number that can evenly divide 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 models, the number M in this optional embodiment can be selected as 6 or 8.
[0081] In an optional embodiment, as shown in FIG8, the grooves 112 can be evenly arranged across the entire circumferential area on the flat surface 11, with equal intervals between them. This ensures the uniformity of the overall strength and hardness of the flat surface 11 and 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 not excluded that certain areas may not have grooves 112 arranged, 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.
[0082] In an optional embodiment, as shown in FIG8, 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 regions, which are used for welding with the current collector 20. These fan-shaped regions are referred to as welding regions 111. These welding regions 111 can be identical fan-shaped regions, 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 regions 111 by eight slots 112 spaced at the same angle of 45°.
[0083] Optionally, as shown in Figure 8, the welding area 111 and the corresponding position of the current collector 20 are welded together by a welding line 1111. The welding line 1111 is a straight spiral weld, which is simple in shape and convenient for welding. It should be noted that, since the flatness of the surface obtained by the present invention is high, the choice of welding line is not limited to a straight spiral weld; any existing welding line can be used.
[0084] In an optional embodiment, as shown in FIG8, a plurality of 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 shown in FIG8, the number of welding lines 1111 and grooves 112 is set to eight. In other embodiments, it is understood that the present invention does not require welding of all welding areas 111, 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., without limitation.
[0085] This embodiment also provides a fully tabbed cylindrical battery, including the aforementioned wound core 10 and two current collectors 20, wherein the two current collectors 20 and two flat surfaces 11 are correspondingly arranged and connected by welding. By employing the aforementioned wound core 10, this fully tabbed cylindrical battery can reduce the probability of short circuits and improve the battery's safety performance.
[0086] 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.
[0087] 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.
[0088] Referring to FIG9, an example of an electric tool, such as an electric screwdriver, to which the present invention can be applied is briefly described. The electric screwdriver 431 houses a motor 433, such as a DC motor, within its main body. 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.
[0089] 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 battery pack 430 can be a battery pack 300. 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 members. 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.
[0090] 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.
[0091] 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.
[0092] 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.
[0093] Referring to FIG10, an example of applying the present invention to an energy storage system for electric vehicles will be described. FIG10 schematically shows an example of the structure of a hybrid vehicle employing a series hybrid system to which the present invention is applied. 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.
[0094] The hybrid vehicle 600 includes an engine 601, a generator 602, an electric drive power conversion device 603, a first drive wheel 604a, a second drive wheel 604b, a first wheel 605a, a second wheel 605b, a battery 608, a vehicle control device 609, various sensors 610, and a charging port 611. The battery pack 300 of the present invention is used in the battery 608.
[0095] 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 604a and the second drive wheel 604b. 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 device 609. These sensors 610 include speed sensors, acceleration sensors, engine speed sensors, etc.
[0096] 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.
[0097] 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.
[0098] 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.
[0099] 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.
[0100] 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 and runs on a motor. However, the present invention can also be effectively applied to parallel hybrid vehicles that use both the output of the engine and the motor 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 the motor. Furthermore, the present invention can also be effectively applied to so-called electric vehicles that do not use an engine and run solely on the drive motor.
[0101] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. 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 the present invention should be included within the scope of protection of the claims of the present invention.
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, wherein, 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; 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; At least the first blank foil (132) is bent toward the center of the core and overlapped to form a flat surface (11); The negative electrode (14) has an insulating layer (141) at the outer edge of the side away from the blank foil of the negative electrode (13) and at the corner position of the starting edge of the winding. The insulating layer (141) at least partially overlaps with the projection of the negative electrode active material layer (142). The insulating layer (142) faces the center of the winding 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 (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 is D, L1≥πD; 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).
2. The winding core according to claim 1, wherein, The negative electrode (14) located at the winding start end (30) is wound inward by a predetermined distance L4 more than the positive electrode (13), where πD≤L1≤πD+L4.
3. The winding core according to claim 1, wherein, The insulating layer (141) is an insulating tape or an insulating ceramic layer.
4. The core according to any one of claims 1-3, wherein, The core is prepared by a flattening method, and the flat surface (11) is a single plane.
5. The core according to any one of claims 1-3, wherein, 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).
6. The core according to any one of claims 1-3, wherein, The diaphragm (15) pre-wound in the through hole (18) has at least two layers.
7. The core according to any one of claims 1-3, wherein, 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).
8. The core according to any one of claims 1-3, wherein, 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).
9. The core according to any one of claims 1-3, wherein, 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.