Pole piece, roll core and battery

Abstract

The utility model discloses a pole piece, a roll core and a battery, the pole piece comprises a pole piece main body and an active layer arranged on the pole piece main body, and the pole piece is divided into two free sections and a middle section between the two free sections in the length direction; the effective width of at least part of the active layer at the free section is different from the effective width of at least part of the active layer at the middle section; the roll core comprises an anode sheet, a diaphragm and a cathode sheet which are stacked in sequence, the width value of the anode active layer in the middle section is A, the width value of the anode active layer in the free section is B, the width value of the cathode active layer in the middle section is C, the width value of the cathode active layer in the free section is D, d0 = A-C and d = B-D are set, both d0 and d are larger than 0, and the width value of the anode active layer in the free section is A; d of at least part of the free sections is larger than d0; the battery cell mainly solves the technical problem that the anode active layer at the free section of the current battery cell adopting a winding type structure cannot completely cover the cathode active layer.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a pole piece, a winding core and a battery. Background Art

[0002] The cells inside current batteries are divided into stacked structures or wound structures, i.e., wound cores. The stacked cells are stacked in the order of anode, separator, cathode, separator, anode, etc. The wound cells are stacked together with anode, separator, and cathode, which are then wound. The anode is also known as the negative electrode in this field, and the cathode is also known as the positive electrode in this field. The separator plays the role of separating the anode and cathode to prevent the anode and cathode from contacting and causing an internal short circuit in the battery. Moreover, the outer dimensions of the separator are usually designed to be larger than the outer dimensions of the anode and cathode to ensure that the anode and cathode do not contact each other. Specifically, during the charge and discharge process of the cell, ions will pass through the separator under the action of the electrolyte and move between the anode and cathode, that is, the ions will be embedded or de-embedded back and forth on the two electrodes.

[0003] More specifically, the anode active layer in the anode sheet usually adopts an OH (overhang) design. Specifically, the so-called OH design is as follows: Figure 1 As shown, after the anode sheet and the cathode sheet are stacked together through the separator, the anode active layer ( Figure 1 The cathode active layer on the cathode sheet (shown in dark grey) needs to be completely covered. Figure 1 In other words, the anode active layer on the anode sheet will protrude relative to the cathode active layer on the cathode sheet in the width direction, so that the area of ​​the anode active layer on the anode sheet is larger than the area of ​​the cathode active layer on the cathode sheet, so that the anode active layer on the anode sheet completely covers the cathode active layer on the cathode sheet, thereby ensuring that the ions precipitated from the cathode sheet can be embedded in the anode after passing through the diaphragm, and ensuring that the ions precipitated from the cathode sheet will not be scattered to areas outside the anode sheet. At present, the coating area of ​​the anode active layer on the anode sheet is usually designed to be 1.2 times that of the cathode active layer to ensure the safety of the battery cell.

[0004] See also Figure 2When the battery cell adopts a wound structure, there will be two free sections after the battery cell is wound, one of which is wound at the innermost head end, and the other is wound at the outermost end. Due to the existence of a certain degree of freedom in the two free sections, the anode and / or cathode sheets at the two free sections are prone to offset and misalignment (also known as the tail swing problem in this field), especially the end free section. During the actual winding process of the battery cell, the end free section is more likely to cause relative misalignment of the anode and cathode sheets under the action of the winding traction tension, resulting in the end of the anode active layer ( Figure 2 The cathode active layer at the end ( Figure 2 The ions released from the cathode sheet will be scattered to the area outside the anode sheet, which will have a greater impact on the battery cell.

[0005] Therefore, there is a need to improve the existing technology. Utility Model Content

[0006] The utility model provides a pole piece, a winding core and a battery, which mainly solve the technical problem that the anode active layer at the free section of the battery core adopting the winding structure cannot completely cover the cathode active layer.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] A pole piece comprises a pole piece body and an active layer arranged on the pole piece body, wherein the pole piece is divided into two free segments and an intermediate segment between the two free segments in the length direction; the effective width of the active layer in at least part of the free segments is different from the effective width of the active layer in at least part of the intermediate segment.

[0009] In one technical solution, the pole piece body is an anode piece body, the active layer is an anode active layer, and the effective width of the anode active layer at least in part of the free segment is greater than the effective width of the anode active layer at at least in part of the middle segment.

[0010] In one of the technical solutions, the length of the single partial free section is L, and L is 0.1m-0.5m.

[0011] In one technical solution, the effective width of the anode active layer at least in part of the free segment is 0.3 mm to 0.7 mm greater than the effective width of the anode active layer at least in part of the middle segment.

[0012] In one of the technical solutions, the difference between the effective width of the anode active layer in the free section and the effective width in the middle section is Δd, and Δd≥0.5L 2 +0.5L+0.2.

[0013] In one technical solution, an insulating layer is provided on the anode sheet body, and the insulating layer and the anode active layer are provided on the same surface of the anode sheet body, and the insulating layer at least covers a portion of the anode active layer in the middle section.

[0014] In one technical solution, the pole piece body is a cathode piece body, the active layer is a cathode active layer, and the effective width of the cathode active layer at least in part of the free segment is smaller than the effective width of the cathode active layer at at least in part of the middle segment.

[0015] In one of the technical solutions, the length of the single partial free section is L, and L is 0.1m-0.5m.

[0016] In one technical solution, the effective width of the cathode active layer at least in part of the free segment is 0.3 mm to 0.7 mm smaller than the effective width of the cathode active layer at least in part of the middle segment.

[0017] In one of the technical solutions, an insulating layer is provided on the cathode sheet body, and the insulating layer and the cathode active layer are provided on the same surface of the cathode sheet body, and the insulating layer at least covers a portion of the cathode active layer at the free segment.

[0018] In one of the technical solutions, a plurality of spaced-apart pole lugs are connected to at least one side of the cathode sheet body in the width direction, and at least a portion of the base of the pole lugs is covered by the insulating layer.

[0019] In one of the technical solutions, the insulating layer also covers at least a portion of the cathode active layer in the middle section. The width of the cathode active layer in the middle section covered by the insulating layer is denoted as E, and the width of the cathode active layer in the free section covered by the insulating layer is denoted as F; F is greater than E.

[0020] In one of the technical solutions, the difference between the effective width of the cathode active layer in the middle section and the effective width of the cathode active layer in the free section is Δd, and Δd≥0.5L 2 +0.5L+0.2.

[0021] The present application also provides a winding core, comprising an anode sheet, a separator and a cathode sheet stacked in sequence, wherein the anode sheet, the separator and the cathode sheet are wound into the winding core, the anode sheet adopts the pole sheet described above, and / or the cathode sheet adopts the pole sheet described above.

[0022] In one of the technical solutions, the effective width value of the anode active layer in the middle section is set to A, the effective width value of the anode active layer at the free section is set to B, the effective width value of the cathode active layer in the middle section is set to C, the effective width value of the cathode active layer at the free section is set to D, d0=AC, d=BD, wherein d0 and d are both greater than 0, and d at at least part of the free section is greater than d0.

[0023] In one of the technical solutions, the d at at least a portion of the outermost circle of the winding core is greater than the d0.

[0024] In one technical solution, A and B are equal, and D is smaller than C.

[0025] In one of the technical solutions, B is greater than A, and C is equal to D.

[0026] In one of the technical solutions, B is greater than A, and D is smaller than C.

[0027] In one of the technical solutions, let the free length of the free segment be L, let △d=d-d0=(BD)-(AC), and △d≥0.5L 2 +0.5L+0.2, where L is 0.1m-0.5m and △d is 0.3mm-0.7mm.

[0028] The present application also provides a battery, comprising a shell and the aforementioned winding core, wherein the winding core is accommodated inside the shell.

[0029] Compared with the prior art, the pole piece provided by the present invention has at least the following beneficial effects:

[0030] This solution designs the effective width of the active layer at the middle section of the electrode to be different from the effective width of the active layer at the free section. For example, when the electrode is an anode electrode, the effective width of the active layer at the free section is greater than the effective width of the active layer at the middle section (that is, the effective width of the anode active layer at the free section is larger than that of the existing design). Or, when the electrode is a cathode electrode, the effective width of the active layer at the free section is smaller than the effective width of the active layer at the middle section (that is, the effective width of the cathode active layer at the free section is smaller than that of the existing design). This ensures that even if the anode electrode or cathode electrode has a certain degree of tail-swinging problem at the free section, the anode active layer at the free section can still completely cover the cathode active layer, thereby improving the stability and safety of the winding core during the charging and discharging process and helping to extend the service life of the winding core, so as to meet the design requirements of high safety and long service life of batteries used in the automotive field. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 A schematic diagram of the structure of a positive electrode sheet (cathode sheet) and a negative electrode sheet (anode sheet) in a winding core provided by the prior art of this application when they are stacked together in an ideal state;

[0033] Figure 2 A schematic diagram of the structure of a positive electrode sheet (cathode sheet) and a negative electrode sheet (anode sheet) in a winding core provided by the prior art of this application when they are stacked on each other in actual situations and a tail-swinging problem occurs;

[0034] Figure 3 Schematic diagram of the structures of three cathode sheets and two anode sheets provided in the embodiments of the present application;

[0035] Figure 4 A schematic structural diagram of a battery cell provided in an embodiment of the present application;

[0036] Figure 5 A schematic structural diagram of a battery provided in an embodiment of the present application.

[0037] Reference numerals:

[0038] 11. Anode sheet body; 12. Anode active layer; 13. Anode ear; 21. Cathode sheet body; 22. Cathode active layer; 23. Cathode ear; 3. Insulation layer; 4. Outer membrane; 5. Positive outer ear; 6. Negative outer ear; 7. Outer shell; 71. Shell; 72. Top cover; 721. Pole; 8. Cell; 10. Middle section; 20. Free section. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0040] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0041] It should be understood that the terms, "upper", "lower", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0044] The present invention provides a pole piece, which includes a pole piece body and an active layer arranged on the pole piece body. Figure 3 , it can be specifically understood that when the electrode is an anode, the electrode body is the anode body 11, and the corresponding active layer is the anode active layer 12; when the electrode is a cathode, the electrode body is the cathode body 21, and the corresponding active layer is the cathode active layer 22. Figure 3 The light grey portion in the “first anode sheet” and “second anode sheet” represents the anode sheet main body 11. Figure 3 The black portion in the "first anode sheet" and "second anode sheet" represents the anode active layer 12. Figure 3 The light grey portion in the “first cathode sheet”, “second cathode sheet” and “third cathode sheet” represents the cathode sheet main body 21. Figure 3 The black portion in the “first cathode sheet”, “second cathode sheet” and “third cathode sheet” represents the cathode active layer 22 .

[0045] Please refer again Figure 3The electrode sheet is divided into a first segment, a middle segment 10, and a last segment in a sequentially connected manner in the length direction. When the electrode sheet is wound during winding, the first segment is wound at the innermost portion, and the last segment is wound at the outermost portion. Since the first and last segments have a certain degree of freedom after winding, they are prone to tail swinging. Therefore, the first and last segments of the electrode sheet can both be referred to as free segments 20. The two free segments 20 are located at both ends of the middle segment 10 in the length direction. The effective width of the active layer at least in part of the free segments 20 is different from the effective width of the active layer at at least part of the middle segment. Specifically, when the electrode sheet is an anode sheet, the effective width B of the anode active layer 12 at at least part of the free segments 20 is greater than the effective width A of the anode active layer 12 at at least part of the middle segment 10 (i.e., the effective width of the anode active layer 12 at the free segments 20 is greater than that of the existing design); or, when the electrode sheet is a cathode sheet, the effective width D of the cathode active layer 22 at at least part of the free segments 20 is less than the effective width C of the cathode active layer 22 at at least part of the middle segment 10. By changing the effective width of the active layer at the free section 20 by at least one of the two methods described above, even if the anode or cathode sheet exhibits a certain degree of tail-swinging at the free section 20, the anode active layer 12 at the free section 20 can still completely cover the cathode active layer 22, thereby improving the stability and safety of the winding core during the charge and discharge process and facilitating the extension of the winding core's service life, thereby meeting the design requirements for high safety and long service life of batteries used in the automotive field. If the electrode sheet is cut by cutting, the effective width of the active layer is the width of the active layer remaining on the electrode coating area after cutting; if the method of coating a portion of the active layer with an insulating layer 3 (preferably TF8) is used, the effective width of the active layer refers only to the width of the active layer not covered by the insulating layer 3 (preferably TF8), and the active layer covered by the insulating layer 3 (preferably TF8) is not counted as the effective width.

[0046] Please refer again Figure 3 Assuming that the free length of a single partial free segment 20 on the anode or cathode sheet (i.e., the first free segment 20 or the last free segment 20) is L, the free length L of the single partial free segment 20 can be specifically understood as the length of the narrowed region of the cathode active layer 22 at the first or last section on the cathode sheet, or the length of the widened region of the anode active layer 12 at the first or last section on the anode sheet. L is generally in the range of 0.1m to 0.5m. Preferably, when the electrode sheet is an anode sheet, (BA) is preferably about 0.3mm-0.7mm, and can be values ​​such as 0.3mm, 0.33mm, 0.35mm, 0.5mm, 0.6mm, or 0.7mm. When the electrode sheet is a cathode sheet, (CD) is preferably about 0.3mm-0.7mm, and can be values ​​such as 0.3mm, 0.33mm, 0.35mm, 0.5mm, 0.6mm, or 0.7mm.

[0047] In one embodiment, the effective width of the anode active layer 12 of the first or last free segment 20 on the anode sheet is 0.3 mm to 0.7 mm larger than the effective width of the anode active layer 12 at at least a portion of the middle segment 10. In one embodiment, the effective width of the anode active layer 12 of the first free segment 20 and the last free segment 20 on the anode sheet is 0.3 mm to 0.7 mm larger than the effective width of the anode active layer 12 at at least a portion of the middle segment 10. In one embodiment, the effective width of the cathode active layer 22 of the first or last free segment 20 on the cathode sheet is 0.3 mm to 0.7 mm smaller than the effective width of the cathode active layer 22 at at least a portion of the middle segment 10. In one embodiment, the effective width of the cathode active layer 22 of the first free segment 20 and the last free segment 20 on the cathode sheet is 0.3 mm to 0.7 mm smaller than the effective width of the cathode active layer 22 at at least a portion of the middle segment 10.

[0048] Please refer again Figure 3 When the electrode is a cathode, an insulating layer 3 may be provided on the cathode body 21. Figure 3 The dark gray portion within the "first cathode sheet," "second cathode sheet," and "third cathode sheet" represents the insulating layer 3. The insulating layer 3 and the cathode active layer 22 are disposed on the same surface of the cathode sheet body 21. The insulating layer 3 covers at least a portion of the side edges of the cathode active layer 22 at the free segment 20, thereby reducing the effective width of the cathode active layer 22 at the free segment 20, such that D is smaller than C. Here, only the cathode active layer 22 at the free segment 20 may be covered. Specifically, the side edges of the cathode active layer 22 at a portion of the free segment 20 may be covered by the insulating layer 3, or the side edges of the cathode active layer 22 at all of the free segment 20 may be covered by the insulating layer 3. The free section 20 and the middle section 10 may also be covered with an insulating layer 3. Specifically, the sides of the cathode active layer 22 of part of the free section 20 and part of the middle section 10 may be covered by the insulating layer 3, or the sides of the cathode active layer 22 of all the free sections 20 and part of the middle section 10 may be covered by the insulating layer 3, or the sides of the cathode active layer 22 of all the free sections 20 and all the middle sections 10 may be covered by the insulating layer 3. However, in the case where both the free section 20 and the middle section 10 are covered with the insulating layer 3, the covered width of the free section 20 is greater than the covered width of the middle section 10. Here, the covered width is in the width direction of the electrode (i.e. Figure 3 The width of the covered portion in the Y direction (in the Y direction). Regardless of the type of coverage, it can be either single-sided coverage in the Y direction or double-sided coverage in the Y direction.

[0049] Similarly, when the electrode sheet is an anode sheet, an insulating layer 3 may also be provided on the anode sheet body 11. The insulating layer 3 and the anode active layer 12 are provided on the same surface of the anode sheet body 11. The insulating layer 3 covers at least a portion of the anode active layer 12 in the middle section 10, thereby reducing the effective width of the anode active layer 12 in the middle section 10, so that A is smaller than B. Here, only the anode active layer 12 in the middle section 10 may be covered. Specifically, the side edges of the anode active layer 12 in a portion of the middle section 10 may be covered by the insulating layer 3, or the side edges of the anode active layer 12 in the entire middle section 10 may be covered by the insulating layer 3. The free section 20 and the middle section 10 may also be covered with an insulating layer 3. Specifically, the sides of the anode active layer 12 of part of the free section 20 and part of the middle section 10 may be covered by the insulating layer 3. Alternatively, the sides of the anode active layer 12 of all the free sections 20 and part of the middle section 10 may be covered by the insulating layer 3. Alternatively, the sides of the anode active layer 12 of all the free sections 20 and all the middle sections 10 may be covered by the insulating layer 3. However, in the case where both the free section 20 and the middle section 10 are covered with the insulating layer 3, the covered width of the free section 20 is smaller than the covered width of the middle section 10. Here, the covered width is in the width direction of the electrode piece (i.e. Figure 3 The width of the covered portion in the Y direction (in the Y direction). Regardless of the type of coverage, it can be either single-sided coverage in the Y direction or double-sided coverage in the Y direction.

[0050] Among them, the insulating layer 3 is preferably TF8 (a type of thermal conductive silicone grease). The thermal conductivity coefficient of TF8 is 12.5W / mK. TF8 has good heat dissipation performance and can more effectively transfer the heat generated by the core to the outside. In addition, TF8 has good stability and can maintain stable heat dissipation performance in high temperature environments.

[0051] The present invention also provides a winding core, which includes an anode sheet, a diaphragm and a cathode sheet. The anode sheet, the diaphragm and the cathode sheet are wound into the winding core. The diaphragm is used to separate the anode sheet and the cathode sheet to avoid direct contact between the anode sheet and the cathode sheet, which may cause an internal short circuit in the winding core. When the anode sheet and the diaphragm are stacked on each other, the side of the anode sheet coated with the anode active layer 12 needs to face the diaphragm. When the cathode sheet and the diaphragm are stacked on each other, the side of the cathode sheet coated with the cathode active layer 22 needs to face the diaphragm. In order to ensure that the anode active layer 12 can still completely cover the cathode active layer 22 even if a certain tail swing problem occurs, the winding core of this embodiment adopts the above-mentioned structural design for the anode sheet and / or the cathode sheet, that is, Figure 3 As shown, the effective width B of the anode active layer 12 of the anode sheet at the free section 20 is increased, or / and the effective width D of the cathode active layer 22 of the cathode sheet at the free section 20 is reduced.

[0052] Optionally, the cathode sheet body 21 is cut so that the cathode sheet body 21 has a width direction (ie Figure 3 One side of the Y direction is connected with multiple Figure 3 The cathode ears 23 are arranged at intervals in the X direction in the anode sheet body 11, and the anode sheet body 11 is cut so that the anode sheet body 11 is Figure 3 One side of the Y direction is connected with multiple Figure 3 The anode ears 13 are arranged at intervals (in the X direction in the middle). After the anode sheet, separator and cathode sheet are stacked and wound into a wound structure, all cathode ears 23 need to be assembled and welded together to form a positive electrode current collector, and all anode ears 13 also need to be assembled and welded together to form a negative electrode current collector. By providing multiple cathode ears 23 and multiple anode ears 13, the active material inside the roll core can be charged or discharged simultaneously at various positions, giving full play to the charging or discharging performance of the roll core. In another embodiment, the cathode sheet body 21 is cut so that the cathode sheet body 21 is Figure 3 The Y direction in the middle) is connected to both sides along the length direction (i.e. Figure 3 The cathode ears 23 are arranged at intervals in the X direction; the anode sheet body 11 is cut so that the anode sheet body 11 is Figure 3 The Y direction in the middle) is connected to both sides along the length direction (i.e. Figure 3 Anode ears 13 are arranged at intervals (in the X direction).

[0053] Further preferably, the present solution also coats at least part of the root of the cathode ear 23 of the cathode sheet with the above-mentioned insulating layer 3. The insulating layer 3 serves to strengthen the root of the cathode ear 23, thereby preventing the cathode ear 23 of the cathode sheet from being too soft and prone to wrinkling. The insulating layer 3 also serves to prevent burrs on the anode sheet from piercing the cathode sheet, thereby reducing the risk of internal short circuit in the winding core and improving the safety of the winding core.

[0054] In other embodiments, the anode sheet body 11 and the cathode sheet body 21 may not have pole ears, that is, the anode sheet body 11 and the cathode sheet body 21 may be square rectangular structures, and the external positive ear can be connected to the cathode sheet body 21 at multiple positions in the length direction through multiple connecting sheets, and the external negative ear can also be connected to the anode sheet body 11 at multiple positions in the length direction through multiple connecting sheets. In this case, the active material in the core can be charged or discharged at each position at the same time to give full play to the charging or discharging performance of the core.

[0055] like Figure 3As shown, let the effective width of the anode active layer 12 in the middle section 10 be A, let the effective width of the anode active layer 12 in the free section 20 be B, let the effective width of the cathode active layer 22 in the middle section 10 be C, let the effective width of the cathode active layer 22 in the free section 20 be D, let d0 = AC, let d = BD, where d0 and d are both greater than 0, and d is greater than d0 at at least part of the free section 20. Specifically, when designing the winding core, for the middle section 10 of the winding core, the conventional design of d0 can be followed. For example, conventionally, A is designed to be 1.2 times C. However, for the free section 20 of the winding core, the present solution designs the d value to be greater than d0. This ensures that even if the anode or cathode sheet in the free section 20 has a certain degree of tail swinging problem, the anode active layer 12 in the free section 20 can still completely cover the cathode active layer 22, thereby improving the stability and safety of the winding core during the charging and discharging process and facilitating the extension of the winding core's service life, thereby meeting the design requirements of high safety and long service life for battery applications in the automotive field. It should be noted that here not the entire free segment may be set to d, it may be a free segment 20, that is, one of the first free segment 20 and the tail free segment 20, or a part of one of them. Optionally, the free segment 20 here includes the tail segment of the outermost circle of the pole piece, and at least part of the tail segment of the outermost circle of the winding core, d is greater than d0.

[0056] In this embodiment, preferably, both free segments 20 of the winding core are designed to have d greater than d0. In other embodiments, either the first free segment 20 or the last free segment 20 of the winding core may be designed to have d greater than d0.

[0057] Please refer again Figure 3 In order to achieve d greater than d0, this embodiment provides the following three technical solutions:

[0058] The first technical solution: Set A, B, C, and D to constant values. A and B can be equal, and D is designed to be smaller than C, so that d is greater than d0. That is, the winding core of this solution is equivalent to using Figure 3 The "second anode sheet" and "second cathode sheet" in the above scheme are equivalent to the winding core of the above scheme. Figure 3 The "second anode sheet" and "third cathode sheet" in the invention;

[0059] The second technical solution: A, B, C, and D are all set to constant values, B is designed to be greater than A, and C is designed to be equal to D, so that d is greater than d0. That is, the winding core of this solution is equivalent to using Figure 3 The "first anode sheet" and "first cathode sheet" in the invention;

[0060] The third technical solution: A, B, C, and D are all set to constant values, B is designed to be greater than A, and D is designed to be less than C, so that d is greater than d0. That is, the winding core of this solution is equivalent to using Figure 3 The "first anode sheet" and "second cathode sheet" in the scheme are equivalent to the winding core of the scheme. Figure 3 The "first type of anode sheet" and the "third type of cathode sheet" in.

[0061] Depend on Figure 3 As can be seen from the figure, both the "second cathode sheet" and the "third cathode sheet" are designed with D smaller than C. To achieve D smaller than C, this embodiment provides the following two manufacturing methods:

[0062] Manufacturing method 1: At the free section 20, the cathode active layer 22 can be cut along the Y direction so that the remaining effective coating width of the cathode active layer 22 is reduced from the original C value to the D value, thereby forming Figure 3 The structure of the "second cathode sheet" shown;

[0063] Manufacturing method 2: By increasing the coating width of the insulating layer 3 at the free section 20, the insulating layer 3 covers a small portion of the surface of the cathode active layer 22, so that the remaining effective coating width of the cathode active layer 22 is reduced from the original C value to the D value, thereby forming Figure 3 The structure of the "third cathode sheet" is shown.

[0064] The second manufacturing method of the above section is further explained. As can be seen from the above, in this embodiment, a plurality of cathode ears 23 arranged at intervals are preferably connected to at least one side in the width direction of the cathode sheet main body 21, and the above-mentioned insulating layer 3 is provided at the root of the cathode ear 23. The width of the insulating layer 3 covering the cathode active layer 22 in the middle section 10 is set to E (E is greater than or equal to 0), and the width of the insulating layer 3 covering the cathode active layer 22 in the free section 20 is set to F. At least in one free section 20, F is greater than E, thereby achieving the purpose of D being less than C. If this cathode sheet and Figure 3 If the "second type of anode sheet" is used in combination, then F = E + d. Since the winding core of this embodiment preferably has two free sections 20 with D smaller than C, the winding core of this embodiment adopts a design in which F is greater than E at both free sections 20.

[0065] Assuming △d=d-d0, the free length L of the free section 20 and the tail swing of the anode or cathode sheet are deduced and calculated. It is found that in order to ensure that the anode active layer 12 at the free section 20 can completely cover the cathode active layer 22, △d and L conform to the quadratic function △d=0.5L 2 +0.5L+0.2, then when △d≥0.5L 2+0.5L+0.2 ensures that the anode active layer 12 at the free segment 20 can completely cover the cathode active layer 22. In other words, as long as the free length L of the free segment 20 is determined, the minimum value of Δd can be determined, thereby confirming the size of the anode active layer 12 widening or the cathode active layer 22 narrowing in the free segment 20. The following table shows three experimental data.

[0066] Serial number Free section length L / m Pole piece tail swing s / mm Width of the active layer widened / narrowed in the free section △d / mm 1 0.2 0.25-0.37 0.3 2 0.3 0.33-0.46 0.4 3 0.4 0.42-0.65 0.5

[0067] Please refer again Figure 3 Since the first free section 20 on the left is wound at the innermost part, its free length L is relatively short. Therefore, in this embodiment, the active layers corresponding to the small sections L of the first two pole ears are preferably modified (widening the anode active layer 12 and narrowing the cathode active layer 22). Since the last free section 20 on the right is wound at the outermost part, its free length L is relatively long. Therefore, in this embodiment, the active layers corresponding to the small sections L of the last three pole ears are preferably modified (widening the anode active layer 12 and narrowing the cathode active layer 22). Among them, L is preferably between 0.1m and 0.5m. According to Δd=0.5L 2 According to the relationship of L + 0.5L + 0.2, the width dimension Δd of the corresponding active layer in the free section 20 falls within the range of 0.3 mm to 0.7 mm.

[0068] like Figure 3 As shown, when A and B are equal, △d is actually the difference between (CD), then (CD) ≥ 0.5L 2 +0.5L+0.2, (CD) specifically 0.3-0.7mm.

[0069] like Figure 3 As shown, when C and D are equal, in fact, △d is the difference between (BA), then (BA) ≥ 0.5L 2 +0.5L+0.2, (BA) specifically is 0.3-0.7mm.

[0070] See also Figure 4 This embodiment also provides a battery cell monomer, which includes an outer film 4 (currently mostly aluminum-plastic film), a positive external pole tab 5, a negative external pole tab 6 and the above-mentioned winding core, wherein the positive external pole tab 5 is connected to the cathode sheet main body 21 through multiple cathode tabs 23, and the negative external pole tab 6 is connected to the anode sheet main body 11 through multiple anode tabs 13. The outer film 4 wraps the winding core and is sealed with the positive external pole tab 5 and the negative external pole tab 6 respectively through hot melt adhesive. The positive external pole tab 5 and the negative external pole tab 6 are both exposed relative to the outer film. When the positive external pole tab 5 and the negative external pole tab 6 are conductive, the winding core can be charged or discharged.

[0071] See also Figure 5 This embodiment also provides a battery, which includes a shell 7 and the above-mentioned battery cell 8. The shell 7 usually includes a shell 71 and a top cover 72. At least one battery cell 8 is accommodated in the shell 71. Two poles 721 are usually provided on the top cover 72, one of which is used to connect to the positive external pole ear 5, and the other pole 721 is used to connect to the negative external pole ear 6, so that the positive and negative electrodes inside the winding core are led outward through the poles 721.

[0072] The above is merely a preferred embodiment of the present invention and only specifically describes the technical principles of the present invention. These descriptions are intended only to explain the principles of the present invention and should not be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention, as well as other specific embodiments of the present invention that can be imagined by those skilled in the art without inventive effort, shall be included within the scope of protection of the present invention.

Claims

1. A pole piece, characterized in that: The invention comprises a pole piece body and an active layer arranged on the pole piece body, wherein the pole piece is divided into two free segments and an intermediate segment between the two free segments in the length direction; the effective width of the active layer at least in part of the free segments is different from the effective width of the active layer at at least in part of the intermediate segment.

2. The pole piece according to claim 1, characterized in that The pole piece body is an anode piece body, the active layer is an anode active layer, and the effective width of the anode active layer in at least part of the free segment is greater than the effective width of the anode active layer in at least part of the middle segment.

3. The pole piece according to claim 2, characterized in that: Assume that the length of the free section of a single portion is L, and L is 0.1m-0.5m.

4. The pole piece according to claim 2, characterized in that: The effective width of the anode active layer at least in part of the free segment is 0.3 mm to 0.7 mm greater than the effective width of the anode active layer at least in part of the middle segment.

5. The pole piece according to claim 3, characterized in that: Assume that the difference between the effective width of the anode active layer in the free section and the effective width in the middle section is Δd, and Δd≥0.5L 2 +0.5L+0.

2.

6. The pole piece according to any one of claims 2 to 5, characterized in that: An insulating layer is provided on the anode sheet main body, and the insulating layer and the anode active layer are provided on the same surface of the anode sheet main body, and the insulating layer at least covers a portion of the anode active layer in the middle section.

7. The pole piece according to claim 1, characterized in that: The pole piece body is a cathode piece body, the active layer is a cathode active layer, and the effective width of the cathode active layer in at least part of the free segment is smaller than the effective width of the cathode active layer in at least part of the middle segment.

8. The pole piece according to claim 7, characterized in that: Assume that the length of the free section of a single portion is L, and L is 0.1m-0.5m.

9. The pole piece according to claim 7, characterized in that: The effective width of the cathode active layer at least in part of the free segment is 0.3 mm to 0.7 mm smaller than the effective width of the cathode active layer at least in part of the middle segment.

10. The pole piece according to any one of claims 7 to 9, characterized in that: An insulating layer is provided on the cathode sheet body, and the insulating layer and the cathode active layer are provided on the same surface of the cathode sheet body, and the insulating layer at least covers a portion of the cathode active layer at the free section.

11. The pole piece according to claim 10, characterized in that: A plurality of spaced-apart electrode lugs are connected to at least one side of the cathode sheet body in the width direction, and at least a portion of the base of the electrode lugs is covered by the insulating layer.

12. The pole piece according to claim 11, characterized in that: The insulating layer also covers at least a portion of the cathode active layer in the middle section. The width of the cathode active layer in the middle section covered by the insulating layer is denoted as E, and the width of the cathode active layer in the free section covered by the insulating layer is denoted as F; F is greater than E.

13. The pole piece according to claim 8, characterized in that: Assume that the difference between the effective width of the cathode active layer in the middle section and the effective width of the cathode active layer in the free section is CD=△d, where △d≥0.5L 2 +0.5L+0.

2.

14. A winding core comprising an anode sheet, a separator and a cathode sheet stacked in sequence, wherein the anode sheet, the separator and the cathode sheet are wound into the winding core, characterized in that: The anode plate adopts the pole plate according to any one of claims 2 to 6, and / or the cathode plate adopts the pole plate according to any one of claims 7 to 13.

15. The winding core according to claim 14, wherein: Assume that the effective width value of the anode active layer in the middle segment is A, the effective width value of the anode active layer at the free segment is B, the effective width value of the cathode active layer in the middle segment is C, the effective width value of the cathode active layer at the free segment is D, d0=AC, d=BD, where d0 and d are both greater than 0, and d at at least part of the free segment is greater than d0.

16. The winding core according to claim 15, wherein: At least part of the outermost circle of the winding core, the d is greater than the d0.

17. The winding core according to any one of claims 15 or 16, characterized in that: A and B are equal, and D is smaller than C.

18. The winding core according to any one of claims 15 or 16, characterized in that B is greater than A, and C is equal to D.

19. The winding core according to any one of claims 15 or 16, characterized in that B is larger than A, and D is smaller than C.

20. The winding core according to any one of claims 15 or 16, wherein △d=d-d0=(BD)-(AC), △d is 0.3mm-0.7mm.

21. A battery, characterized in that: The invention comprises a shell and a winding core according to any one of claims 14 to 20, wherein the winding core is accommodated inside the shell.

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