Electrode sheet, jelly roll, battery and preparation method for jelly roll

Abstract

An electrode sheet, a jelly roll, a battery and a preparation method for the jelly roll, which relate to the technical field of batteries. The electrode sheet comprises a current collector, an active material layer and a reinforcing layer. The current collector comprises a tab and a main body, wherein one side of the tab is connected to the main body; the active material layer is arranged on the main body; and the reinforcing layer is arranged at the end of the tab that is close to the main body.

Description

Pole piece, winding core, battery and winding core preparation method

[0001] This application claims priority to Chinese patent applications with application numbers 202323671291.0 and 202311874122.9 filed with the China Patent Office on December 31, 2023. The entire contents of the above applications are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a pole piece, a winding core, a battery, and a winding core preparation method. Background Art

[0003] In related art, a battery cell includes a housing and a stacked or wound arrangement of a positive electrode sheet, a separator, and a negative electrode sheet. The electrode sheet includes a current collector and an active material layer disposed on the current collector. The current collector includes a material area and a blank area located to one side of the material area. The active material layer is disposed in the material area, while the blank area is not. Typically, the blank area serves as the electrode tab, which includes a tab body and a tab root that connects the tab body to the battery. SUMMARY OF THE INVENTION

[0004] Due to the thin thickness of the current collector, the tabs can easily collapse or fold at the base of the tabs during the winding process, resulting in poor reliability of the tabs. Folding of the tabs also reduces the yield of the core and leads to material waste.

[0005] The present application provides a pole piece, a winding core, a battery and a winding core preparation method, which can improve the problem of poor reliability of the pole piece.

[0006] In a first aspect, the present application provides a pole piece. The pole piece includes a current collector, an active material layer, and a reinforcement layer. The current collector includes a tab and a body, one side of the tab being connected to the body; the active material layer being disposed on the body; and the reinforcement layer being disposed on the end of the tab closest to the body.

[0007] In a second aspect, the present application also provides a winding core, comprising a positive electrode sheet, a separator and a negative electrode sheet stacked and wound, wherein the positive electrode sheet is the aforementioned electrode sheet, or both the positive electrode sheet and the negative electrode sheet are the aforementioned electrode sheets.

[0008] In a third aspect, the present application also provides a battery comprising the aforementioned winding core.

[0009] In a fourth aspect, the present application also provides a winding core preparation method, which includes: obtaining the aforementioned pole piece for winding, or obtaining the aforementioned winding core. Beneficial effects

[0010] In the present application, by providing a reinforcement layer at one end of the tab close to the main body, the thickness of the tab root can be increased, thereby increasing the strength of the tab root, and then effectively preventing the tab from collapsing or folding when the pole piece is wound, thereby ultimately improving the reliability of the pole piece. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG1 is a schematic structural diagram of an embodiment of the present application as viewed from a cut surface of a pole piece;

[0012] Figure 2 is an enlarged view of point A in Figure 1;

[0013] FIG3 is a schematic diagram showing the positions of the strengthening layer on the A side and the strengthening layer on the B side of the pole piece provided in an embodiment of the present application;

[0014] FIG4 is a schematic structural diagram of the A surface of the pole piece provided in an embodiment of the present application;

[0015] FIG5 is a schematic structural diagram of the B side of the pole piece provided in an embodiment of the present application;

[0016] FIG6 is a schematic structural diagram of a strengthening layer provided in an embodiment of the present application;

[0017] FIG7 is a schematic structural diagram of another strengthening layer provided in an embodiment of the present application;

[0018] FIG8 is a schematic structural diagram of a winding core as viewed from a cut surface of a pole piece provided in an embodiment of the present application;

[0019] FIG9 is an enlarged view of point C in FIG8 ;

[0020] FIG10 is a schematic diagram of a first process for preparing a core according to an embodiment of the present application;

[0021] FIG11 is a second schematic diagram of a process for preparing a core according to an embodiment of the present application;

[0022] FIG12 is a third schematic diagram of the process for preparing a roll core provided in an embodiment of the present application.

[0023] Description of reference numerals:

[0024] 001-pole piece;

[0025] 011-current collector; 111-ear; 112-body;

[0026] 012-active material layer; 013-reinforcement layer; 131-first adhesive layer; 132-expansion layer; 134-second adhesive layer; 135-PI layer;

[0027] 002-positive electrode sheet; 003-diaphragm; 004-negative electrode sheet. Modes for Carrying Out the Invention

[0028] Before introducing a pole piece, winding core, battery and winding core preparation method of the present application, the relevant technologies of the present application are first introduced.

[0029] In the related art, since the thickness of the current collector of the electrode is relatively thin, the electrode tabs are easily folded during the winding of the electrode with the electrode tabs and the subsequent processing of the electrode with the electrode tabs to form finished battery cells through multiple steps, thereby reducing the electrode yield and causing waste of materials.

[0030] Based on this, a smoothing plate is usually provided to smooth the electrode to prevent the tab from folding. However, the smoothing plate needs to be placed in different positions for different electrode pieces, which has poor versatility and can easily cause damage such as cracking of the electrode piece.

[0031] As multi-tab and full-tab solutions become increasingly popular, insulating layer coating has become necessary to improve the reliability of the electrode. However, the full-tab solution is limited in the coating process and cannot apply insulating layers of different widths. This limits the insulating layer's ability to protect the electrode and still poses the risk of tab folding.

[0032] Based on this, the embodiments of the present application provide a pole piece, a winding core, a battery, and a winding core manufacturing method to solve the problem of poor pole piece reliability. The present application describes the pole piece, the winding core, the battery, and the winding core manufacturing method through the following embodiments.

[0033] Please refer to Figure 1, which is a schematic structural diagram of an embodiment of the present application as viewed from a cut surface of a pole piece 001. The embodiment of the present application provides a pole piece 001 for use in a wound-type core. The pole piece 001 includes a current collector 011, an active material layer 012, and a reinforcement layer 013. The current collector 011 includes a pole tab 111 and a main body 112. One side of the pole tab 111 is connected to the main body 112. The active material layer 012 is disposed on the main body 112. The reinforcement layer 013 is disposed on one end of the pole tab 111 close to the main body 112.

[0034] It is understood that the active material layer 012 covers the main body 112. The tab 111 includes a tab body and a tab root portion connecting the tab body to the main body 112. The strengthening layer 013 is disposed at one end of the tab 111 near the main body 112. It can be disposed only at the tab root portion, or partially at the tab root portion and partially at the tab body 112.

[0035] The strengthening layer 013 is used to strengthen the end of the tab 111 close to the main body 112. The strengthening layer 013 has insulating properties and includes but is not limited to an insulating layer and an adhesive layer.

[0036] In this embodiment, by providing a reinforcement layer 013 at one end of the tab 111 near the main body 112, the thickness of the base of the tab can be increased, thereby increasing the strength of the base of the tab. This effectively prevents the tab from collapsing or folding when the pole piece 001 is wound, ultimately improving the reliability of the pole piece 001. This improves the yield rate of the wound core using the pole piece 001 and controls the manufacturing cost of the wound core.

[0037] In addition, a material with a strength greater than that of the current collector 011 may be selected as the strengthening layer 013 , so that the strengthening layer 013 can improve the strength of the base of the tab with a smaller thickness.

[0038] Please refer to Figure 2, which is an enlarged view of point A in Figure 1. In one embodiment, a winding center is defined, and the pole piece 001 has a surface A facing the winding center and a surface B facing away from the winding center. Both the surface A and the surface B are provided with a strengthening layer 013 and an active material layer 012, as shown in Figures 4 and 5. Figure 4 is a schematic structural diagram of the surface A of the pole piece 001 provided in an embodiment of the present application, and Figure 5 is a schematic structural diagram of the surface B of the pole piece 001 provided in an embodiment of the present application.

[0039] In this embodiment, by providing the strengthening layer 013 on both sides of the tab 111 , both sides of the tab can be strengthened simultaneously, thereby improving the symmetry of the reinforcement on both sides of the tab root and further enhancing reliability.

[0040] 2 , in one embodiment, along the width direction of the electrode 001 , the strengthening layer 013 on side A has a width dimension L1. The strengthening layer 013 on side B has a width dimension L2. The electrode tab 111 has a width dimension H1, satisfying the following conditions: 15% H1 ≤ L1 ≤ 50% H1, and 15% H1 ≤ L2 ≤ 50% H1.

[0041] It is understood that L1 and L2 include but are not limited to 15% H1, 20% H1, 30% H1, 40% H1, 45% H1, and 50% H1. For example, when H1 is 6.5 mm, L1 and L2 include but are not limited to 0.975 mm, 1.3 mm, 1.95 mm, 2.6 mm, 2.925 mm, and 3.25 mm.

[0042] In addition, L1 can be equal to L2 or unequal. When L1 and L2 are equal, they can be aligned or staggered on both sides of the tab. When L1 and L2 are unequal, one end face of the reinforcement layer 013 on side A can be flush with one end face of the reinforcement layer 013 on side B in the width direction of the pole piece 001.

[0043] In this embodiment, by making the above-mentioned limitations on L1 and L2, on the one hand, it can avoid that L1 and L2 are too small to support the tabs; on the other hand, it can avoid that L1 and L2 are too large to be conducive to winding and electrical connection with the busbar.

[0044] In one embodiment, the following conditions are satisfied: L1 < L2, and 30% H1 ≤ L2 ≤ 50% H1.

[0045] Illustratively, 50%L2≤L1≤90%L2.

[0046] It is understood that L1 includes but is not limited to 50% L2, 60% L2, 70% L2, 80% L2, 86% L2, and 90% L2. For example, when L2 is 2.5 mm, L1 includes but is not limited to 1.25 mm, 1.5 mm, 1.75 mm, 2 mm, 2.15 mm, and 2.25 mm.

[0047] Accordingly, in combination with the previous embodiment, 15% H1 ≤ L1 ≤ 45% H1, and 30% H1 ≤ L2 ≤ 50% H1. L1 includes, but is not limited to, 15% H1, 20% H1, 30% H1, 40% H1, and 45% H1. L2 includes, but is not limited to, 30% H1, 36% H1, 38% H1, 40% H1, 45% H1, and 50% H1. For example, when H1 is 6.5mm, L1 includes, but is not limited to, 0.975mm, 1.3mm, 1.95mm, 2.6mm, and 2.925mm, and L2 includes, but is not limited to, 1.95mm, 2.34mm, 2.47mm, 2.6mm, 2.925mm, and 3.25mm.

[0048] It can be understood that because side A faces the winding center, it is in a compressed state when winding the pole piece 001; side B faces away from the winding center and is in a stretched state when winding the pole piece 001. Therefore, in this embodiment, the width dimension L1 of the reinforcement layer 013 on side A is set to be smaller than the width dimension L2 of the reinforcement layer 013 on side B, so that the connection surface area between side A and reinforcement layer 013 is smaller. This can reduce the obstruction of the reinforcement layer 013 on side A to the bending of the pole piece 001 when winding the pole piece 001, facilitating smooth winding of the pole piece 001.

[0049] Referring to FIG. 2 , in one embodiment, along the thickness direction of the electrode 001 , the strengthening layer 013 on the A side has a thickness dimension D1 , and the strengthening layer 013 on the B side has a thickness dimension D2 , satisfying: D1 > D2 .

[0050] Illustratively, 40%D1≤D2≤80%D1.

[0051] It is understood that D2 includes but is not limited to 40% D1, 50% D1, 60% D1, 70% D1, 75% D1, and 80% D1. For example, when D1 = 0.05 mm, D0 includes but is not limited to 0.02 mm, 0.025 mm, 0.03 mm, 0.035 mm, and 0.04 mm.

[0052] Because L1 is smaller than L2, the support effect of the reinforcement layer 013 on the A side on the tab is weaker than the reinforcement effect of the reinforcement layer 013 on the B side on the tab. Based on this, in this embodiment, by setting the thickness dimension D1 of the reinforcement layer 013 on the A side to be greater than the thickness dimension D2 of the reinforcement layer 013 on the B side, the thickness of the reinforcement layer 013 on the A side can be increased, thereby improving the reinforcement effect of the reinforcement layer 013 on the A side on the tab, and ultimately achieving stable support for the base of the tab by the reinforcement layer 013 on the A side.

[0053] In one embodiment, the electrode 001 is a positive electrode, and the side of the strengthening layer 013 on the A side facing away from the active material layer 012 on the A side is coplanar with the side of the strengthening layer 013 on the B side facing away from the active material layer 012 on the B side, as shown in Figure 3. Figure 3 is a schematic diagram of the positions of the strengthening layer 013 on the A side and the strengthening layer 013 on the B side of the electrode 001 provided in an embodiment of the present application.

[0054] In this embodiment, through the above arrangement, the strengthening layer 013 on the A side 013 and the B side of the pole piece 001 can share a positioning reference, thereby improving the convenience of setting the strengthening layer 013 and further improving the manufacturing efficiency of the pole piece 001.

[0055] Please refer to Figure 3. In one embodiment, on surface A, the strengthening layer 013 is spaced apart from the edge of the main body 112, and the distance between the strengthening layer 013 and the edge of the main body 112 is L4; on surface B, the strengthening layer 013 is spaced apart from the edge of the main body 112, and the distance between the strengthening layer 013 and the edge of the main body 112 is L5, satisfying: L4>L5.

[0056] In this embodiment, through the above-mentioned limitation, the distance between the reinforcement layer 013 on the A side of the pole piece 001 and the edge of the main body 112 is larger than that on the B side, so that the support of the reinforcement layer 013 on the A side for the pole ear on the A side is weaker than the support of the reinforcement layer 013 on the B side for the pole ear on the B side, thereby making it easier to bend the pole ear toward the center of the winding core when winding the pole piece 001, so as to realize the directional bending of the pole ear, which can ultimately facilitate the subsequent connection of the pole ear and the busbar.

[0057] Please refer to FIG. 2 . In one embodiment, along the width direction of the pole piece 001 , the strengthening layer 013 on the A surface has a width dimension L1 , which satisfies: 15% L1 ≤ L4 ≤ 27% L1 .

[0058] Exemplarily, 0.25mm≤L5<L4≤1.5mm, for example, L4=0.7mm, L5=0.5mm; L4=0.5mm, L5=0.3mm; L4=0.38mm, L5=0.2mm.

[0059] In this embodiment, by limiting the distance L4 between the reinforcement layer 013 on the A side and the edge of the main body 112, on the one hand, it can avoid the distance between the reinforcement layer 013 and the edge of the main body 112 being too small, thereby avoiding the active material layer 012 and the reinforcement layer 013 under compression in the A side from interfering with each other due to deformation; on the other hand, it can avoid the distance between the reinforcement layer 013 and the edge of the main body 112 being too large, which can prevent the root of the tab from being strengthened.

[0060] In addition, by limiting the minimum value of L4, the minimum value of the distance between the reinforcement layer 013 on the A side and the edge of the main body 112 can be limited, thereby ensuring that the pole piece has guidance when winding, thereby improving the smoothness of winding.

[0061] 2 , in one embodiment, along the thickness direction of the electrode 001 , the electrode 001 has a thickness dimension D4 at the active material layer 012 , and a thickness dimension D0 at the reinforcement layer 013 , satisfying: 50% D4 ≤ D0 ≤ 90% D4.

[0062] It is understood that in the art, along the thickness direction of the electrode piece 001, the distance between the surface of the active material layer 012 on one side of the current collector 011 and the surface of the active material layer 012 on the other side of the current collector 011 is the thickness dimension D4 of the electrode piece 001 at the active material layer 012. In addition, the distance between the surface of the reinforcement layer 013 on one side of the current collector 011 and the surface of the reinforcement layer 013 on the other side of the current collector 011 is the thickness dimension D0 of the electrode piece 001 at the reinforcement layer 013.

[0063] Wherein, D0 includes but is not limited to 50%D4, 60%D4, 70%D4, 80%D4, and 90%D4. For example, when D4=0.124mm, D0 includes but is not limited to 0.062mm, 0.08mm, 0.09mm, 0.10mm, and 0.116mm.

[0064] In one embodiment, the reinforcement layer 013 includes a first adhesive layer 131 disposed on the tab 111. Specifically, the first adhesive layer 131 is a thermosetting adhesive or a UV curing adhesive or a mixture of a UV curing adhesive and an insulating filler.

[0065] It is understood that a thermosetting adhesive is a thermosetting resin, which can be at least one of phenolic resin, urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin, silicone resin, polyurethane, and polyimide. A UV-curable adhesive is a UV-curable resin. The UV-curable resin can be at least one of epoxy acrylate, polyacrylic acid, polyester acrylate, acrylate containing cyanurate functional groups, and silicone / fluorine photocurable resin. Thermosetting or UV-curable adhesives typically have a faster curing time, allowing the reinforcement layer 013 to cure quickly and bond strongly to the tab. This reduces the waiting time for the glue to cure and improves production efficiency.

[0066] In this embodiment, the use of the aforementioned adhesive can, on the one hand, enhance the support provided by the reinforcement layer 013 to the tab by pre-folding the tab of the electrode sheet 001 during winding and curing the reinforcement layer 013, thereby effectively preventing the tab from collapsing or folding. This improves the yield rate of the wound assembly and controls the manufacturing cost of the wound assembly. Furthermore, the first adhesive layer 131 can be cured quickly, allowing it to quickly cure and strongly bond to the tab. This not only facilitates the connection between the cured layer and the tab, but also reduces the time required for curing the first adhesive layer 131, thereby improving production efficiency.

[0067] Please refer to Figure 6, which is a schematic diagram of the structure of the strengthening layer 013 provided in an embodiment of the present application. In one embodiment, the strengthening layer 013 further includes an expansion layer 132, which is disposed on a side of the first adhesive layer 131 away from the tab 111.

[0068] It can be understood that the expansion layer 132 is an expansion tape.

[0069] In this embodiment, when the battery cell is assembled and liquid is injected, the expansion layer 132 expands to fill the gap at the edge between the positive electrode sheet 002 and the negative electrode sheet 004. This not only insulates the positive electrode sheet 002 and the negative electrode sheet 004, but also tightens the edges of the tab and the separator 003 to form a whole. This increases the vibration resistance of the tab, reduces the shaking amplitude of the tab during impact, and effectively reduces the possibility of internal short circuits caused by external impact, ultimately improving the safety and reliability of the battery.

[0070] Please refer to Figure 7, which is a schematic diagram of the structure of another strengthening layer 013 provided in an embodiment of the present application. In one embodiment, strengthening layer 013 includes a first adhesive layer 131, an expansion layer 132, a second adhesive layer 134, and a PI (polyimide) layer 135, arranged in sequence, along a direction away from the tab. PI layer 135 is disposed on the side of expansion layer 132 facing away from first adhesive layer 131, via second adhesive layer 134. Second adhesive layer 134 includes, but is not limited to, UV-curable resins and acrylic adhesives. Specifically, second adhesive layer 134 is a thermosetting adhesive, a UV-curable adhesive, or a mixture of a UV-curable adhesive and insulating filler.

[0071] In this embodiment, the above configuration can, on the one hand, improve the insulation of the strengthening layer 013, thereby improving reliability; on the other hand, improve the strength of the strengthening layer 013, thereby preventing the strengthening layer 013 from being scratched by burrs at the tab.

[0072] In one embodiment, taking a 4680 cylindrical battery cell and electrode 001 as the positive electrode as an example, the dimensions and values ​​involved are as follows:

[0073] Parameter meaning value / mm L1 Width of A surface strengthening layer 013 2.000 L2 Width of B surface strengthening layer 013 2.500 L3 Width of cut tab 3.000 L4 Spacing between A surface strengthening layer 013 and edge of main body 112 0.45 L5 Spacing between B surface strengthening layer 013 and edge of main body 112 0.300 H1 Width of tab 111 6.5 D1 Thickness of A surface strengthening layer 013 0.050 D2 Thickness of B surface strengthening layer 013 0.035 D3 Thickness of current collector 011 0.012 D4 Thickness of pole piece 001 0.124

[0074] Table 1. Dimensions and values

[0075] In Table 1, the width L3 of the cut tab on the A side = the width H1 of the tab 111 - the width L1 of the strengthening layer 013 on the A side - the distance L4 between the strengthening layer 013 on the A side and the edge of the main body 112; the width L3 of the cut tab on the B side = the width H1 of the tab 111 - the width L2 of the strengthening layer 013 on the B side - the distance L5 between the strengthening layer 013 on the B side and the edge of the main body 112.

[0076] In addition, the width of the cut tab in Table 1 refers to the cutting size of the tab formed by cutting the blank area of ​​the current collector.

[0077] Correspondingly, an embodiment of the present application also provides a winding core, comprising a positive electrode sheet 002, a separator 003 and a negative electrode sheet 004 that are wound together, wherein the positive electrode sheet 002 is the electrode sheet 001 disclosed in some embodiments of the present application, or the positive electrode sheet 002 and the negative electrode sheet 004 are both the electrode sheet 001 disclosed in some embodiments of the present application.

[0078] It is understood that, based on the battery design, the negative electrode sheet 004 should completely wrap the positive electrode sheet 002. To prevent the tabs of the positive electrode sheet 002 from bending, at least the structure of the positive electrode sheet 002 should be the same as that of the electrode sheet 001 disclosed in some embodiments of this application.

[0079] In this embodiment, by adopting the electrode sheet 001 disclosed in some embodiments of the present application as the positive electrode sheet 002 of the winding core, the thickness of the root of the electrode ear can be increased, thereby increasing the strength of the root of the electrode ear. Furthermore, when the positive electrode sheet 002 is wound, the electrode ear of the positive electrode sheet 002 can be prevented from bending at the root of the electrode ear to avoid the electrode ear from folding, thereby ultimately improving the yield rate of the winding core and controlling the manufacturing cost of the winding core.

[0080] Please refer to Figures 8 and 9. Figure 8 is a schematic structural diagram of a winding core provided by an embodiment of the present application as viewed from a cut surface of the electrode sheet 001, and Figure 9 is an enlarged view of point C in Figure 8. In one embodiment, the winding core has a winding center, and the surface of the positive electrode sheet 002 facing the winding center is surface A. Along the width direction of the positive electrode sheet 002, the strengthening layer 013 on surface A has a first end face facing the active material layer 012 on surface A and a second end face facing away from the active material layer 012 on surface A. With the plane parallel to the winding center as the projection plane and the direction perpendicular to the projection plane as the projection direction, in the projection plane, the orthographic projection of the edge of the negative electrode sheet 004 is located between the orthographic projection of the first end face and the orthographic projection of the second end face.

[0081] In FIG9 , the edge of the negative electrode sheet 004 extends beyond the edge of the main body 112 of the positive electrode sheet 002 by a dimension H3 , and the distance between the first end surface and the edge of the main body 112 of the positive electrode sheet 002 is L4 . Correspondingly, L4 < H3 .

[0082] Exemplarily, L4 is 0.7 mm and H3 is 1 mm.

[0083] In this embodiment, through the above-mentioned limitations, the reinforcing layer 013 can not only protect the tabs of the positive electrode sheet 002 from folding, but also prevent the edge of the negative electrode sheet 004 from being stuck in the gap between the first end face and the edge of the main body 112 of the positive electrode sheet 002, thereby preventing the edge of the negative electrode sheet from being stuck in the gap and causing a short circuit, thereby improving the reliability of the winding core.

[0084] Please refer to FIG. 9 . In one embodiment, in the projection plane, the orthographic projection of the edge of the diaphragm 003 is located between the orthographic projection of the second end surface and the orthographic projection of the edge of the main body 112 of the negative electrode sheet 004 .

[0085] It can be understood that the tabs of the positive electrode sheet 002 and the tabs of the negative electrode sheet 004 are located at the two ends of the winding center, respectively, and the edge of the negative electrode sheet 004 closest to the tabs of the positive electrode sheet 002 is the edge of the main body of the negative electrode sheet 004. Therefore, the distance between the second end surface and the edge of the main body 112 of the negative electrode sheet 004 is arranged opposite to the edge of the separator 003, thereby achieving insulation isolation between the negative electrode sheet 004 and the positive electrode sheet 002.

[0086] The surface of the positive electrode sheet 002 facing away from the winding center is surface B. On surface B, as shown in FIG9 , along the width direction of the positive electrode sheet 002, the distance between the second end surface and the edge of the main body 112 of the positive electrode sheet 002 is equal to the width dimension L2 of the reinforcement layer 013 on surface B + the distance L5 between the reinforcement layer 013 on surface B and the edge of the main body 112 on surface B. Along the width direction of the positive electrode sheet 002, the distance by which the edge of the separator 003 protrudes beyond the edge of the main body 112 of the positive electrode sheet 002 is H2. The orthographic projection of the edge of the separator 003 is between the orthographic projection of the second end surface and the orthographic projection of the edge of the main body 112 of the negative electrode sheet 004. Accordingly, L5 < H2 < L5 + L2.

[0087] Exemplarily, L5 is 0.3 mm, L2 is 2.5 mm, and correspondingly, 0.3 mm < H2 < 2.8 mm, for example, H2 = 2 mm.

[0088] In this embodiment, through the above-mentioned limitations, the edge of the diaphragm 003 is arranged opposite to the reinforcing layer 013, so that in the wound core, the gaps between the tabs of the positive electrode sheet 002, the edge of the diaphragm 003 and the edge of the negative electrode sheet 004 can be filled with the reinforcing layer 013, so that the edges of these three components are integrated, thereby improving the structural stability of the core.

[0089] In addition, when the strengthening layer 013 includes an expansion layer, the expansion layer can expand when the battery cell is assembled and liquid is injected, thereby filling the gap between the tab of the positive electrode sheet 002 and the edge of the negative electrode sheet 004, thereby squeezing the edge of the separator 002, the edge of the negative electrode sheet 004, and the position where the tab of the positive electrode sheet 002 faces the expansion layer 132 into one. In this way, the positive electrode sheet 002 and the negative electrode sheet 004 are insulated and isolated, and the tab of the positive electrode sheet 002, the edge of the negative electrode sheet 004, and the edge of the separator 003 are pressed together to form a whole, thereby increasing the vibration resistance of the tab, reducing the amplitude of shaking between them during impact, and effectively preventing the possibility of internal short circuits caused by external impacts, ultimately improving the safety and reliability of the battery.

[0090] Accordingly, embodiments of the present application further provide a battery, which includes the winding core disclosed in some embodiments of the present application.

[0091] It is understood that the battery further comprises a battery box and a cell housing disposed within the battery box. The winding core is disposed within the cell housing, and electrolyte is injected into the cell housing.

[0092] In this embodiment, by adopting the winding core disclosed in some embodiments of the present application, the yield rate of the battery is improved, thereby controlling the manufacturing cost of the battery.

[0093] Accordingly, an embodiment of the present application also provides a method for preparing a core, which includes: obtaining the pole piece 001 disclosed in some embodiments of the present application for winding, or obtaining the core disclosed in some embodiments of the present application.

[0094] In this embodiment, by adopting the pole piece 001 or winding core disclosed in some embodiments of the present application, the pole ear 111 of the pole piece 001 can be prevented from collapsing or folding during winding, thereby improving the yield of the winding assembly and controlling the manufacturing cost of the winding assembly.

[0095] In one embodiment, the reinforcement layer 013 includes a first adhesive layer 131 arranged on the pole piece, and the method includes: setting the first adhesive layer 131 on one end of the pole ear 111 of the pole piece 001 close to the main body 112; when winding, pre-folding the pole ear 111 of the pole piece 001, and curing the first adhesive layer 131 on the pre-folded pole ear 111 of the pole piece 001.

[0096] Exemplarily, the first adhesive layer 131 is a thermosetting adhesive or a UV curing adhesive or a mixture of a UV curing adhesive and an insulating filler, wherein the insulating filler may be ceramic powder.

[0097] In this way, the tab of the positive electrode sheet 002 can be bent in a preset direction and shaped, thereby improving the strength of the tab and preventing the tab of the positive electrode sheet 002 from collapsing or folding.

[0098] Among them, when the first adhesive layer 131 is a thermosetting adhesive, the reinforcing layer 013 is cured by heating the reinforcing layer 013; when the first adhesive layer 131 is a UV curing adhesive or a mixture of a UV curing adhesive and an insulating filler, the reinforcing layer 013 is cured by irradiating it with external rays through a UV curing device.

[0099] In one embodiment, before pre-bending the tab 111 of the electrode sheet 001 , the method further includes: baking the strengthening layer 013 .

[0100] In this embodiment, the strengthening layer 013 is baked to be initially solidified, thereby controlling the adhesiveness of the strengthening layer 013 and preventing it from randomly adhering to other components, thereby facilitating smoother preparation of the winding core.

[0101] In one embodiment, the strengthening layer 013 further includes an expansion layer 132 . After the first adhesive layer 131 is disposed on one end of the tab 111 of the electrode 001 close to the main body 112 , the method further includes: disposing the expansion layer 132 on the side of the first adhesive layer 131 away from the tab 111 .

[0102] In this embodiment, by providing the expansion layer 132, when the battery cell is assembled and liquid is injected, the expansion layer expands, thereby filling the gap between the tab of the positive electrode sheet 002 and the edge of the negative electrode sheet 004, thereby squeezing the edge of the separator 002, the edge of the negative electrode sheet 004, and the location where the tab of the positive electrode sheet 002 faces the expansion layer 132 into one. In this way, the positive electrode sheet 002 and the negative electrode sheet 004 are insulated and isolated, and the tab of the positive electrode sheet 002, the edge of the negative electrode sheet 004, and the edge of the separator 003 are pressed together to form a whole. This increases the vibration resistance of the tab, reduces the amplitude of shaking between them during impact, and effectively prevents the possibility of internal short circuits caused by external impacts, ultimately improving the safety and reliability of the battery.

[0103] In one embodiment, the strengthening layer 013 further includes a second viscose layer 134 and a PI layer 135. After the expansion layer 134 is arranged on the side of the first viscose layer 131 away from the tab 111, the method further includes: arranging the second viscose layer 134 on the side of the expansion layer 132 away from the first viscose layer 131; and arranging the PI layer 135 on the side of the second viscose layer 134 away from the expansion layer 132.

[0104] In this embodiment, the above configuration can, on the one hand, improve the insulation of the strengthening layer 013, thereby improving reliability; on the other hand, improve the strength of the strengthening layer 013, thereby preventing the strengthening layer 013 from being scratched by burrs at the tab.

[0105] In one embodiment, the method further includes: preparing and baking a strengthening layer 013; setting the baked strengthening layer 013 on one end of the pole ear 111 of the pole piece 001 close to the main body 112; when winding, pre-folding the pole ear 111 of the pole piece 001, and curing the strengthening layer 013 on the pre-folded pole ear 111.

[0106] The strengthening layer 013 includes a first adhesive layer 131 , an expansion layer 132 , a second adhesive layer 134 and a PI layer 135 stacked in sequence.

[0107] In this embodiment, the strengthening layer 013 is prepared and then disposed on the tab 111 of the electrode 001 , so that the strengthening layer 013 and the active material can be separately manufactured and coated on the current collector 011 , thereby improving the manufacturing efficiency of the electrode 011 .

[0108] Based on the above embodiments, the preparation of the winding core is described in detail as follows.

[0109] 1. When the reinforcement layer 013 includes a first adhesive layer 131, and the first adhesive layer 131 is a mixture of a UV-curable adhesive and an insulating filler, as shown in FIG10, FIG10 is a schematic diagram of a process for preparing a winding core according to an embodiment of the present application. The winding core preparation method includes:

[0110] S100, preparing glue: mixing a UV curable adhesive and an insulating filler to prepare glue;

[0111] S200, preparing the positive electrode sheet 002: obtaining the electrode body, applying glue to the base of the electrode tab of the electrode body, and drying the glue to form a strengthening layer 013, i.e., a first adhesive layer 131. It will be understood that when the strengthening layer 013 only has the first adhesive layer 131, drying the strengthening layer 013 is equivalent to drying the first adhesive layer 131.

[0112] S300 , forming a winding core: winding the positive electrode sheet 002 , and pre-folding the tab of the positive electrode sheet 002 during winding, and curing the reinforcing layer 013 on the tab of the pre-folded positive electrode sheet 002 through a UV curing device.

[0113] 2. When the reinforcement layer 013 includes a first adhesive layer 131 and an expansion layer 132, and the first adhesive layer 131 is a mixture of a UV-curable adhesive and an insulating filler, as shown in FIG11 , FIG11 is a second schematic flow diagram of a core preparation process provided in an embodiment of the present application. The core preparation method includes:

[0114] S100, preparing glue: mixing a UV curable adhesive and an insulating filler to prepare glue;

[0115] S200, preparing the positive electrode sheet 002: obtaining the electrode body, applying glue to the base of the electrode tab of the electrode body, and drying the glue to form a first adhesive layer 131;

[0116] S300, disposing the expansion layer 132 on the first adhesive layer 131 to form a strengthening layer 013;

[0117] S400 , forming a winding core: winding the positive electrode sheet 002 , and pre-folding the tab of the positive electrode sheet 002 during winding, and curing the reinforcing layer 013 on the tab of the pre-folded positive electrode sheet 002 through a UV curing device.

[0118] 3. When the reinforcement layer 013 includes a first adhesive layer 131, an expansion layer 132, a second adhesive layer 134, and a PI layer 135, and the first adhesive layer 131 is a mixture of a UV-curable adhesive and an insulating filler, as shown in FIG12, FIG12 is a schematic diagram of a third process for preparing a winding core according to an embodiment of the present application. The winding core preparation method includes:

[0119] S100, preparing the adhesive tape: coating both surfaces of the expansion layer 132 with a mixture of a UV curable adhesive and an insulating filler to form a first adhesive layer 131 and a second adhesive layer 134, respectively; then disposing a PI layer 135 on the side of the second adhesive layer 134 facing away from the expansion layer 132; and then baking the second adhesive layer 135 to obtain a strengthening layer 013;

[0120] S200, preparing the positive electrode sheet 002: obtaining the electrode body, and placing the strengthening layer 013 on the base of the electrode ear of the electrode body;

[0121] S300 , forming a winding core: winding the positive electrode sheet 002 , and pre-folding the tab of the positive electrode sheet 002 during winding, and curing the reinforcing layer 013 on the tab of the pre-folded positive electrode sheet 002 through a UV curing device.

Claims

1. A pole piece (001), comprising: A current collector (011), comprising a tab (111) and a body (112), one side of the tab (111) being connected to the body (112); An active material layer (012), disposed on the body (112); A reinforcement layer (013), disposed at one end of the tab (111) close to the body (112).

2. The electrode tab (001) according to claim 1, wherein, Defining a winding center, the pole piece (001) having an A side facing the winding center and a B side facing away from the winding center; both the A side and the B side are provided with the reinforcement layer (013) and the active material layer (012).

3. The electrode sheet (001) according to claim 2, wherein, Along the width direction of the pole piece (001), the reinforcement layer (013) on the A side has a width dimension L1, the reinforcement layer (013) on the B side has a width dimension L2, and the tab (111) has a width dimension H1, satisfying: 15%H1 ≤ L1 ≤ 50%H1, 15%H1 ≤ L2 ≤ 50%H1.

4. The electrode tab (001) according to claim 3, wherein, L1 < L2.

5. The electrode sheet (001) according to claim 4, wherein, 50%L2 ≤ L1 ≤ 90%L2.

6. The electrode sheet (001) according to claim 5, wherein, 15%H1 ≤ L1 ≤ 45%H1.

7. The electrode sheet (001) according to any one of claims 4-6, wherein, Along the thickness direction of the pole piece (001), the reinforcement layer (013) on the A side has a thickness dimension D1, the reinforcement layer (013) on the B side has a thickness dimension D2, satisfying: D1 > D2.

8. The electrode sheet (001) according to any one of claims 4-7, wherein, The pole piece (001) is a positive electrode piece (002), and 30%H1 ≤ L2 ≤ 50%H1.

9. The electrode sheet (001) according to any one of claims 4-8, wherein, The side of the reinforcement layer (013) on the A side facing away from the active material layer (012) on the A side is coplanar with the side of the reinforcement layer (013) on the B side facing away from the active material layer (012) on the B side.

10. The electrode sheet (001) according to any one of claims 2-9, wherein, In the A side, the reinforcement layer (013) is spaced from the edge of the body (112), and the distance between the reinforcement layer (013) and the edge of the body (112) is L4; in the B side, the reinforcement layer (013) is spaced from the edge of the body (112), and the distance between the reinforcement layer (013) and the edge of the body (112) is L5, satisfying: L4 > L5.

11. The electrode tab (001) according to claim 10, wherein, Along the width direction of the pole piece (001), the reinforcement layer (013) on the A side has a width dimension L1, satisfying: 15%L1 ≤ L4 ≤ 27%L1.

12. The electrode sheet (001) according to claim 11, wherein, 0.25mm ≤ L5 < L4 ≤ 1.5mm.

13. The electrode sheet (001) according to any one of claims 1-12, wherein, Along the thickness direction of the pole piece (001), the pole piece (001) has a thickness dimension D4 at the active material layer (012), and the pole piece (001) has a thickness dimension D0 at the reinforcement layer (013), satisfying: 50%D4 ≤ D0 ≤ 90%D4.

14. The electrode sheet (001) according to any one of claims 1-13, wherein, The reinforcement layer (013) includes a first adhesive layer (131) disposed on the tab (111).

15. The electrode sheet (001) according to claim 14, wherein, The reinforcement layer (013) further includes an expansion layer (132), and the expansion layer (132) is disposed on the side of the first adhesive layer (131) facing away from the tab (111).

16. The electrode sheet (001) according to claim 15, wherein, The reinforcing layer (013) further includes a second adhesive layer (134) and a PI layer (135). The PI layer (135) is disposed on a side of the expansion layer (132) facing away from the first adhesive layer (131) through the second adhesive layer (134).

17. The electrode sheet (001) according to claim 16, wherein, The first adhesive layer (131) and / or the second adhesive layer (134) is a thermosetting binder or a UV-curable binder or a mixture of a UV-curable binder and an insulating filler.

18. A core, comprising a wound positive electrode sheet (002), a separator (003) and a negative electrode sheet (004), wherein, The positive electrode sheet (002) is the electrode sheet (001) described in any one of claims 1-17, or both the positive electrode sheet (002) and the negative electrode sheet (004) are the electrode sheets (001) described in any one of claims 1-17.

19. The core according to claim 18, wherein, Define the winding center. The surface of the positive electrode sheet (002) facing the winding center is the A surface. Along the width direction of the positive electrode sheet (002), the reinforcing layer (013) of the A surface has a first end face facing the active material layer (012) of the A surface and a second end face facing away from the active material layer (012) of the A surface; with a plane parallel to the winding center as the projection plane and a direction perpendicular to the projection plane as the projection direction, in the projection plane, the positive projection of the edge of the main body (112) of the negative electrode sheet (004) is located between the positive projection of the first end face and the positive projection of the second end face.

20. The core according to claim 19, wherein, In the projection plane, the positive projection of the edge of the separator (003) is located between the positive projection of the second end face and the positive projection of the edge of the main body (112) of the negative electrode sheet (004).

21. A battery, comprising a wound core as described in any one of claims 18-20.

22. A method for preparing a core, comprising: Obtain the electrode sheet (001) described in any one of claims 1-17 for winding, or obtain a wound core as described in any one of claims 18-20.

23. The method for preparing a core according to claim 22, wherein, The reinforcing layer (013) includes a first adhesive layer (131), and the method includes: Before winding the electrode sheet (001), dispose the first adhesive layer (131) at an end of the tab (111) of the electrode sheet (001) close to the main body (112); during winding, pre-fold the tab (111) of the electrode sheet (001), and cure the first adhesive layer (131) on the pre-folded tab (111) of the electrode sheet (001).

24. The method for preparing a core according to claim 23, before pre-folding the tab (111) of the electrode sheet (001), the method further includes: Bake the reinforcing layer (013).

25. According to the method for preparing a wound core as described in claim 23 or 24, the reinforcing layer (013) further includes an expansion layer (132). After disposing the first adhesive layer (131) at an end of the tab (111) of the electrode sheet (001) close to the main body (112), the method further includes: Dispose the expansion layer (132) on a side of the first adhesive layer (131) facing away from the tab (111).

26. The method for preparing a core according to claim 25, wherein the reinforcing layer (013) further comprises a second adhesive layer (134) and a PI layer (135). After the expansion layer (132) is disposed on a side of the first adhesive layer (131) away from the tab (111), the method further comprises: Disposing the second adhesive layer (134) on a side of the expansion layer (132) away from the first adhesive layer (131); Disposing the PI layer (135) on a side of the second adhesive layer (134) away from the expansion layer (132).

27. The method for preparing a core according to any one of claims 22-26, the method further comprises: Preparing and baking the reinforcing layer (013); Disposing the baked reinforcing layer (013) at an end of the tab (111) of the electrode sheet (001) close to the main body (112); During winding, pre-folding the tab (111) of the electrode sheet (001), and performing a curing treatment on the reinforcing layer (013) on the pre-folded tab (111).

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