Stacked core and lithium ion secondary battery

Abstract

The utility model relates to the technical field of batteries, and discloses a laminated core and a lithium ion secondary battery. The second pole pieces and the first pole pieces are arranged in a stacked mode, the second pole pieces are arranged between every two adjacent layers of first pole pieces, and diaphragms are arranged between the second pole pieces and the first pole pieces; the first pole piece positioned on the outermost layer is provided with a first concave part; the gummed paper comprises a first bonding part and a second bonding part, and the first bonding part is connected with the outer edge of the diaphragm in the third direction; and one side, far away from the second pole piece in the first direction, of the first pole piece on the outermost layer is bonded with the second bonding part. According to the laminated core provided by the utility model, the liquid storage capacity of the single-face area of the first pole piece on the outermost layer can be increased, the infiltration effect can be improved, electrolyte deficiency caused by expansion force on the outermost layer can be avoided, the CB value of the single-face area can be improved, the current density of the single-face area can be reduced, the problem of lithium precipitation in the single-face area can be solved, and the pole pieces can be prevented from being layered or scattered; the battery safety performance is improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a stacked-core lithium-ion secondary battery. Background Technology

[0002] Lithium-ion batteries (LIIBs) are widely used in portable electronic devices, electric vehicles, and energy storage systems due to their high specific energy density, wide temperature range, and long cycle life. From a performance perspective, stacking technology theoretically offers advantages in energy density, cycle life, and rate performance. However, during cycling, the expansion force of the electrodes can cause electrolyte loss in the outermost layer, affecting battery safety and cycle life. Electrode delamination or scattering can also compromise battery safety. Utility Model Content

[0003] In view of this, the present invention provides a stacked cell and lithium-ion secondary battery to solve the problems of poor electrolyte wetting and electrode delamination or scattering in stacked cells.

[0004] In a first aspect, this utility model provides a stacked core, comprising:

[0005] First electrode plate;

[0006] The second electrode is stacked with the first electrode and is disposed between every two adjacent layers of the first electrode. A diaphragm is disposed between the second electrode and the first electrode.

[0007] The outermost first electrode plate has a first recess;

[0008] The adhesive tape includes a first adhesive portion and a second adhesive portion. The first adhesive portion is connected to the outer edge of the diaphragm in a third direction. The first electrode sheet located on the outermost layer is bonded to the second adhesive portion on the side away from the second electrode sheet in a first direction.

[0009] The design of the first concave part of the outermost first electrode can increase the electrolyte storage capacity of the single-sided area of ​​the outermost first electrode and improve the wetting effect, avoid electrolyte loss due to expansion force in the outermost layer, increase the CB value of the single-sided area, reduce the current density of the single-sided area, solve the lithium plating problem in the single-sided area, and at the same time, the design of the adhesive paper can prevent the electrode from delaminating or falling off, and improve the battery safety performance.

[0010] In one optional embodiment, the outermost first electrode includes a first current collector and a first active layer, wherein the first active layer is located on the side of the first current collector facing the second electrode along a first direction;

[0011] Both the first current collector and the first active layer are provided with a first recess, and the orthographic projection of the first recess on the first current collector and the orthographic projection of the first recess on the first active layer at least partially coincide.

[0012] By creating a first recess by forming a hole in the first current collector and the first active layer of the first electrode on the outermost layer, the current density in the single-sided area is reduced, the wetting effect in the single-sided area is improved, poor wetting in the single-sided area is avoided, the amount of electrolyte in the single-sided area is increased, the CB value in the single-sided area is increased, and lithium plating in the single-sided area is avoided.

[0013] In one optional embodiment, the depth of the first recess of the first current collector is less than or equal to the thickness of the first current collector, the thickness of the first current collector is H1, and the value of H1 is in the range of 10μm≤H1≤30μm; the depth of the first recess of the first active layer is less than or equal to the total thickness of the first electrode.

[0014] By creating a through-hole in the first current collector of the outermost first electrode, the current density in the single-sided region of the stacked core can be reduced, and the wetting effect in the single-sided region can be improved, thus avoiding poor wetting in the single-sided region. By creating a non-through-hole in the first current collector of the outermost first electrode, the current density in the single-sided region can be reduced. At the same time, combined with the creation of holes in the first active layer, in addition to the above effects, the CB value in the single-sided region can also be improved, thus avoiding lithium plating in the single-sided region.

[0015] In one optional embodiment, the outermost first electrode sheet has two sets of first recesses on the side facing the second electrode sheet along the first direction. The two sets of first recesses are arranged opposite each other along the second direction. The size of a single set of first recesses along the second direction is P mm, where P satisfies 1 / 15×L1≤P≤1 / 2×L1, where L1 is the size of the first electrode sheet along the second direction, and the unit of L1 is mm.

[0016] By satisfying 1 / 15×L1≤P≤1 / 2×L1, P can not only ensure sufficient electrolyte storage in the single-sided area, guarantee the electrolyte wetting effect, improve the CB value of the single-sided area, effectively reduce the current density of the single-sided area, and solve the lithium plating problem in the single-sided area, but also avoid the loss of active material of the first electrode, ensure the capacity of the cell, and avoid affecting the cycle life of the cell.

[0017] In one alternative embodiment, the first recess includes a plurality of first holes, which are spaced apart on the first electrode along a second direction and / or a third direction.

[0018] The projection of the first pore formed by the first current collector along the first direction is within the projection range of the first pore formed by the first active layer; the area of ​​a single first pore formed by the first current collector is S1μm. 2S1 satisfies 10% × S2 ≤ S1 ≤ 100% × S2, where S2 is the area of ​​a single first pore formed on the first active layer, and the unit of S2 is μm. 2 .

[0019] By satisfying 10%×S2≤S1≤100%×S2, not only can the current density of the single-sided area be effectively reduced and the lithium plating problem in the single-sided area be effectively solved, but also excessive loss of active material during the hole formation process can be avoided and leakage of positive electrode coating material can be prevented.

[0020] In one optional embodiment, the total opening area of ​​the first recess formed by the first current collector is S3 mm. 2 S3 satisfies 1 / 1000×S4≤S3≤1 / 50×S4, where S4 is the total area of ​​the first current collector, and the unit of S4 is mm. 2 .

[0021] By satisfying 1 / 1000×S4≤S3≤1 / 50×S4, not only can sufficient liquid storage space be ensured for the first electrode, but the breakage of the first current collector after rolling can also be avoided, excessive loss of active material during the pore-forming process can be avoided, and battery capacity loss can be reduced.

[0022] In one optional embodiment, the pore size of the first pore formed by the first active layer is D1, where D1 satisfies 50μm≤D1≤1000μm; the pore spacing of the first pore formed by the first active layer is B1, where B1 satisfies 50μm≤B1≤5000μm.

[0023] The aperture of the first hole formed by the first current collector is D2, which satisfies D2≤D1 and 10μmm≤D2≤500μmm; the hole spacing of the first hole formed by the first current collector is B2, which satisfies 50μm≤B2≤20000μm.

[0024] It not only ensures sufficient liquid storage space for the first electrode, but also prevents the first current collector from breaking after rolling, avoids excessive loss of active material during the pore-forming process, reduces battery capacity loss, and effectively reduces the current density of the single-sided area, thus effectively solving the problem of lithium plating in the single-sided area.

[0025] In one alternative embodiment, the first electrode in the inner layer is provided with a second recess.

[0026] By setting a first recess in the first electrode sheet located on the outermost layer, the electrolyte storage capacity and wetting effect of the first electrode sheet on one side are increased, avoiding electrolyte loss due to expansion force in the outermost layer. At the same time, the CB value of the single side area is increased, the current density of the single side area is reduced, and the lithium plating problem in the single side area is solved. Meanwhile, by setting a second recess in the first electrode sheet located on the inner layer, the electrolyte storage capacity and wetting effect of the stacked core can be further increased, the CB value of the local area can be increased, and lithium plating in the local area can be avoided.

[0027] In one optional embodiment, the first electrode in the inner layer includes a second current collector and a second active layer, the second active layer being located on both sides of the second current collector in a first direction; the thickness of the second current collector is H2, and the value of H2 is in the range of 7μm≤H2≤15μm;

[0028] The second active layer is provided with a second recess; the depth of the second recess is less than or equal to the thickness of the second active layer.

[0029] And / or, the second recess includes a second hole, the distance between the second hole and the edge of the first electrode is Q1, Q1 satisfies 100μm≤Q1≤5000μm.

[0030] For the first electrode in the inner layer, a second recess is formed by creating a hole in the second active layer, thereby increasing the liquid storage capacity, increasing the CB value of the hole-forming area, and alleviating local lithium plating; the distance Q1 between the second hole and the edge of the first electrode is reduced by satisfying 100μm≤Q1≤5000μm, thereby reducing burrs during die cutting and effectively alleviating edge lithium plating.

[0031] In one optional embodiment, a plurality of second holes are spaced apart around the edge region of the second active layer; the distance between the second holes and the outer edge of the second active layer is Q2, wherein Q2 satisfies 1000μm≤Q2≤5000μm;

[0032] And / or, the second hole is disposed in the corner region of the second active layer, and the opening area S5 of each corner region satisfies 0.5×S6≤S5≤S6, where S6 is the area of ​​a single corner region, and the units of S5 and S6 are both mm. 2 The side length of a single corner region is a, and the value of a ranges from 1 / 10×L1≤a≤1 / 8×L1. L1 is the dimension of the first pole piece along the second direction. The units of a and L1 are both mm.

[0033] And / or, the second hole is disposed in the central region of the second active layer, and the opening area S7 of the central region satisfies 0.1×S4≤S7≤0.5×S4, where S4 is the total area of ​​the second current collector, and the units of S7 and S4 are both mm. 2 .

[0034] It effectively alleviates the problem of lithium plating at the edge of the first electrode, improves the wetting effect in the corner area of ​​the first electrode, avoids cell capacity loss, improves the wetting effect in the middle of the first electrode, and effectively alleviates black spots in the middle of the electrode.

[0035] In one alternative embodiment, the second electrode is provided with a third recess.

[0036] This improves the lithium intercalation capability of the negative electrode, reduces the lithium intercalation detour, enhances the electrolyte wetting ability, and mitigates the lithium desorption problem.

[0037] In one optional embodiment, the second electrode includes a third current collector and a third active layer, wherein the third active layer is located on both sides of the third current collector in a first direction;

[0038] The third active layer has a third recess; the depth of the third recess in the third active layer is less than or equal to the thickness of the third active layer.

[0039] For the second electrode, a third recess is formed by creating pores in the third active layer, thereby improving the lithium intercalation capability of the negative electrode, reducing the lithium intercalation detour, improving electrolyte wetting, and mitigating the lithium desorption problem.

[0040] In one optional embodiment, the third recess includes a plurality of third holes, and the distance between any third hole and the outer edge of the second electrode is Q3, wherein Q3 satisfies 100μm≤Q1≤5000μm.

[0041] It effectively alleviates the problem of lithium deposition at the edge of the second electrode.

[0042] In one optional embodiment, the third recess includes a plurality of grooves, which are spaced apart along a third direction; the width of the groove is T, which satisfies 20μm≤T≤500μm; the distance between two adjacent grooves is Q4, which satisfies 200μm≤Q4≤3000μm.

[0043] To avoid excessive loss of active material during the pore-forming process, reduce battery capacity loss, and ensure sufficient liquid storage space for the second electrode.

[0044] In one alternative implementation, the areal density of the outermost first electrode is less than or equal to the areal density of the innermost first electrode.

[0045] This reduces the current density of the outermost first electrode, thus solving the problem of lithium deposition on a single side.

[0046] In one optional embodiment, the total bonding area between each first electrode and the second adhesive portion is S8, where S8 satisfies 1 / 10×S4≤S8≤4 / 10×S4, where S4 is the total area of ​​the first current collector, and both S8 and S4 are in mm. 2 .

[0047] This allows the electrode sheets to be fixed with adhesive tape, preventing them from delaminating or falling off and improving battery safety. S8 satisfies 1 / 10×S4≤S8≤4 / 10×S4, which ensures sufficient adhesion to effectively prevent electrode delamination or falling off and improve cell safety, while also avoiding poor electrolyte wetting.

[0048] In one optional embodiment, the bonding width between each first electrode and the second adhesive portion is W1, and the value of W1 is in the range of 4mm≤W1≤20mm; the bonding dimension of the first adhesive portion along the first direction is J, and J satisfies 0.5mm≤J≤2mm.

[0049] It can ensure sufficient adhesion to effectively prevent electrode delamination or scattering, thus improving cell safety, and also avoid poor electrolyte wetting.

[0050] In one alternative embodiment, the adhesive tape includes a first adhesive tape, which is a non-porous adhesive tape.

[0051] The first adhesive tape is pasted on both sides of the first electrode in the third direction. The total adhesive length of the first adhesive tape along the second direction is K1 mm. K1 satisfies 1 / 2×L1≤K1≤4 / 5×L1. L1 is the dimension of the first electrode along the second direction, and the unit of L1 is mm.

[0052] And / or, a first electrode tab extends from one side of the first electrode in the second direction, and a second electrode tab extends from one side of the second electrode in the second direction, with the second electrode tab and the first electrode tab being spaced apart relative to each other along a third direction; a first adhesive tape is pasted on the side of the first electrode in the second direction close to the first electrode tab, and the dimension of the first adhesive tape along the third direction is K2 mm, where K2 satisfies 1 / 2×L2≤K2≤4 / 5×L2, and L2 is the distance between the first electrode tab and the second electrode tab along the third direction, with the unit of L2 being mm;

[0053] And / or, the first adhesive tape is pasted on the side of the first electrode away from the first electrode tab along the second direction, and the dimension of the first adhesive tape along the third direction is K3 mm, K3 satisfies 1 / 2×L3≤K3≤4 / 5×L3, where L3 is the dimension of the first electrode along the third direction, and the unit of L3 is mm.

[0054] By employing a first adhesive tape, the coverage area of ​​the adhesive tape on the stacked core is ensured, thereby ensuring sufficient adhesion, effectively preventing electrode delamination or scattering, improving stacked core stability, and enhancing process yield and safety. At the same time, by setting a first recess on the outermost first electrode, a second recess on the inner first electrode, and / or a third recess on the second electrode, wettability is improved in conjunction with positive or negative electrode pore formation, while mitigating lithium desorption issues.

[0055] In one alternative embodiment, the adhesive tape includes a second adhesive tape, which is a perforated adhesive tape;

[0056] The second adhesive tape is pasted on both sides of the first electrode in the third direction. The total adhesive length of the second adhesive tape along the second direction is K4 mm. K4 satisfies 1 / 2×L1≤K4≤L1, where L1 is the dimension of the first electrode along the second direction, and the unit of L1 is mm.

[0057] And / or, a first electrode tab extends from one side of the first electrode in the second direction, and a second electrode tab extends from one side of the second electrode in the second direction, with the second electrode tab and the first electrode tab being spaced apart relative to each other along a third direction; a second adhesive tape is pasted on the side of the first electrode in the second direction close to the first electrode tab, and the dimension of the second adhesive tape along the third direction is K5 mm, where K5 satisfies 1 / 2×L2≤K5≤4 / 5×L2, and L2 is the distance between the first electrode tab and the second electrode tab along the third direction, with the unit of L2 being mm;

[0058] And / or, the second adhesive tape is pasted on the side of the first electrode away from the first electrode tab along the second direction. The dimension of the second adhesive tape along the third direction is K6 mm. K6 satisfies 1 / 2×L3≤K6≤L3, where L3 is the dimension of the first electrode along the third direction, and the unit of L3 is mm.

[0059] By employing a second adhesive tape, not only is the coverage area of ​​the adhesive tape on the stacked core ensured, thus guaranteeing sufficient adhesion and effectively preventing electrode delamination or scattering, thereby improving the stability of the stacked core, increasing process yield and safety, but the second adhesive tape is also porous, facilitating electrolyte wetting. Furthermore, by providing a first recess on the outermost first electrode, a second recess on the innermost first electrode, and / or a third recess on the second electrode, wettability is improved in conjunction with positive or negative electrode pore formation, while mitigating lithium desorption issues.

[0060] Secondly, this utility model also provides a lithium-ion secondary battery, including: a packaging shell, and a stacked core as described above; the packaging shell has a receiving cavity, and the stacked core is built into the receiving cavity.

[0061] The lithium-ion secondary battery of the second aspect includes the stacked core of the first aspect, and therefore, the lithium-ion secondary battery of the second aspect includes all the beneficial effects of the stacked core of the first aspect. Attached Figure Description

[0062] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0063] Figure 1 This is a perspective view of the stacked core of this utility model before the adhesive paper is applied;

[0064] Figure 2 This is a perspective view of one of the first pole pieces located in the outermost layer of the stacked core of this utility model;

[0065] Figure 3 This is a perspective view of the outermost first electrode sheet of the stacked core of this utility model;

[0066] Figure 4 This is a front view of the first electrode sheet located on the outermost layer of the stacked core of this utility model;

[0067] Figure 5 This is a front view of the first current collector of the first electrode plate located on the outermost layer of the stacked core of this utility model;

[0068] Figure 6 This is a front view of the first active layer of the first electrode sheet located on the outermost layer of the stacked core of this utility model;

[0069] Figure 7 This is a perspective view of the first electrode plate located in the inner layer of the stacked core of this utility model;

[0070] Figure 8 This is a front view of the first electrode sheet located in the inner layer of the stacked core of this utility model;

[0071] Figure 9 This is a front view of the first type of recess in the first active layer of the first electrode sheet located in the inner layer of the stacked core of this utility model.

[0072] Figure 10 This is a front view of the second type of recess in the first active layer of the first electrode sheet located in the inner layer of the stacked core of this utility model.

[0073] Figure 11 This is a front view of the third type of recess in the first active layer of the first electrode sheet located in the inner layer of the stacked core of this utility model.

[0074] Figure 12 This is a perspective view of the second electrode sheet of the stacked core of this utility model;

[0075] Figure 13 This is a front view of the first type of recessed portion of the second pole piece of the stacked core of this utility model;

[0076] Figure 14 This is a front view of the second type of recessed portion of the second electrode sheet of the stacked core of this utility model;

[0077] Figure 15 This is a perspective view of the stacked core of this utility model after the adhesive paper has been applied.

[0078] Figure 16 This is a front view of the stacked core of this utility model after the first type of adhesive paper has been bonded together;

[0079] Figure 17 This is a front view of the stacked core of this utility model after the second type of first adhesive paper has been bonded.

[0080] Figure 18 This is a front view of the stacked core of this utility model after the third type of first adhesive paper has been bonded together;

[0081] Figure 19 This is a front view of the stacked core of this utility model after the fourth type of first adhesive paper has been bonded.

[0082] Figure 20 This is a front view of the stacked core of this utility model after the first type of second adhesive paper has been bonded together;

[0083] Figure 21 This is a front view of the stacked core of this utility model after the second type of adhesive paper has been bonded.

[0084] Figure 22 This is a front view of the stacked core of this utility model after the third type of second adhesive paper has been bonded.

[0085] Explanation of reference numerals in the attached figures:

[0086] 10. First electrode; 101. First recess; 1011. First hole; 102. Second recess; 1021. Second hole; 11. First current collector; 12. First active layer; 121. Edge region; 122. Corner region; 123. Central region; 13. First tab; 14. Second current collector; 15. Second active layer;

[0087] 20. Second electrode plate; 201. Third recess; 2011. Third hole; 2012. Groove; 21. Third current collector; 22. Third active layer; 23. Second tab;

[0088] 30. Diaphragm;

[0089] 40. Adhesive tape; 401. First adhesive part; 402. Second adhesive part; 41. First adhesive tape; 42. Second adhesive tape. Detailed Implementation

[0090] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0091] In related technologies, due to the special manufacturing process, the aluminum foil thickness of the single-sided area of ​​the stacked battery is thicker than that of the double-sided area, and the single-sided area has only one layer of paste. Therefore, during cycling, the current density of the single-sided area is higher, and the potential of the outermost single-sided area of ​​the positive electrode is lower than that of the double-sided area. The positive electrode is more prone to lithium de-lithiation, and the corresponding negative electrode is more prone to lithium plating. In addition, the stacked battery has the problem of core delamination during the manufacturing process. Therefore, the hot pressing pressure of stacked batteries is generally greater than that of wound batteries. As a result, poor wetting is prone to occur in the middle of the stacked cores, and interface problems are likely to occur.

[0092] To address the problems existing in the aforementioned related technologies, this utility model provides a stacked core and a battery. By creating pores in the single-sided area of ​​the positive electrode, the current density in the single-sided area can be reduced, and the CB value of the single-sided area can be increased, thereby alleviating the lithium plating problem in the single-sided area. The CB value is an indicator used to measure the capacitance provided per unit area in a specific region of a lithium battery. Furthermore, it is combined with other folded local pore-forming techniques on the positive electrode to alleviate the local lithium plating problem. Combined with the pore-forming process on the negative electrode, the lithium intercalation detour of the negative electrode is reduced, and the negative electrode kinetics are improved, further improving the charging capacity and cycle performance of the stacked core and alleviating the lithium plating problem. In addition, by setting the recess and increasing the coverage area of ​​the adhesive tape, the stability and safety of the stacked core can be improved while avoiding the problem of poor wetting.

[0093] The following is combined with Figures 1 to 22 The following describes embodiments of the present invention.

[0094] According to an embodiment of the present invention, in one aspect, a stacked core is provided, comprising:

[0095] First electrode 10;

[0096] The second electrode 20 is stacked with the first electrode 10. Please refer to [link / reference]. Figure 1 As shown, the second electrode 20 is disposed between each two adjacent layers of the first electrode 10, and a diaphragm 30 is disposed between the second electrode 20 and the first electrode 10;

[0097] The outermost first electrode 10 is provided with a first recess 101;

[0098] The adhesive tape 40 includes a first adhesive portion 401 and a second adhesive portion 402. The first adhesive portion 401 is connected to the outer edge of the diaphragm 30 in a third direction. The first electrode 10 located on the outermost layer is bonded to the second adhesive portion 402 on the side away from the second electrode 20 in a first direction.

[0099] It should be noted that the "outermost" electrode in the text refers to the electrode located on the outermost side of the entire laminated structure. The "inner" electrode, located in the laminated structure closest to the packaging shell along the thickness direction of the core, refers to the electrode in the laminated structure that is distinct from the outermost electrode. The first electrode 10 is a positive electrode, and the second electrode 20 is a negative electrode. The first electrode 10, located on the outermost side facing the second electrode 20, forms a first recess 101 through a hole. This first recess 101 can be... Figure 4 The structure shown is as follows. During the battery cell's operating cycle, the expansion force of the electrodes is released outwards, making the outermost interface most prone to interface anomalies. On one hand, the aluminum foil thickness of the outermost positive electrode is higher than other layers, resulting in a higher current density; on the other hand, the outermost layer is prone to electrolyte loss due to expansion force. By providing a first recess 101 on the outermost first electrode 10, the electrolyte storage capacity of the single-sided area of ​​the outermost first electrode 10 is increased, and the wetting effect is improved, preventing electrolyte loss due to expansion force. Simultaneously, the CB value of the single-sided area is increased, and the current density of the single-sided area is reduced, solving the lithium plating problem in the single-sided area. The electrode is fixed with adhesive tape 40, so that the first adhesive portion 401 is bonded to the outer edge of the separator 30, and the side of the outermost first electrode 10 away from the second electrode 20 along the first direction is bonded to the second adhesive portion 402, thereby preventing electrode delamination or scattering and improving battery safety performance.

[0100] Furthermore, holes can be created through machining or laser processing.

[0101] In some embodiments, see Figure 2 and Figure 3 As shown, the outermost first electrode 10 includes a first current collector 11 and a first active layer 12, with the first active layer 12 located on the side of the first current collector 11 facing the second electrode 20 along a first direction;

[0102] Both the first current collector 11 and the first active layer 12 are provided with a first recess 101, and the orthographic projection of the first recess 101 on the first current collector 11 and the orthographic projection of the first recess 101 on the first active layer 12 at least partially overlap.

[0103] It should be noted that the side of the outermost first electrode 10 away from the second electrode 20 along the first direction does not contain the first active layer 12. For the outermost first electrode 10, the first current collector 11 and the first active layer 12 can be perforated simultaneously to form the first recess 101; alternatively, the first current collector 11 can be perforated in advance, and then the first active layer 12 can be coated on the perforated first current collector 11 to form the first active layer 12, and finally the first active layer 12 can be perforated to form the first recess 101. The perforation of the first active layer 12 can be performed before or after rolling.

[0104] By creating a first recess 101 through pores in the first current collector 11 and the first active layer 12 of the outermost first electrode 10, the current density in the single-sided area is reduced, the wetting effect in the single-sided area is improved, poor wetting in the single-sided area is avoided, the amount of electrolyte in the single-sided area is increased, the CB value in the single-sided area is increased, and lithium plating in the single-sided area is avoided.

[0105] In some embodiments, the depth of the first recess 101 of the first current collector 11 is less than or equal to the thickness of the first current collector 11, the thickness of the first current collector 11 is H1, and the value of H1 is in the range of 10μm≤H1≤30μm; the depth of the first recess 101 of the first active layer 12 is less than or equal to the total thickness of the first electrode 10.

[0106] It should be noted that for the outermost first electrode 10, the first recess 101 can penetrate the first current collector 11, that is, the pore depth of the first current collector 11 is equal to the thickness of the first current collector 11; the first recess 101 may not penetrate the first current collector 11, that is, the pore depth of the first current collector 11 is less than the thickness of the first current collector 11. The thickness H1 of the first current collector 11 of the outermost first electrode 10 is in the range of 10μm≤H1≤30μm. For example, H1 can be 10μm, 15μm, 20μm, 26μm or 30μm. Preferably, the value range of H1 is 15μm≤H1≤20μm.

[0107] By creating a through-hole first recess 101 on the first current collector 11 of the outermost first electrode 10, the current density of the single-sided region of the stacked core can be reduced, and the wetting effect of the single-sided region can be improved, thus avoiding poor wetting of the single-sided region. By creating a non-through-hole first recess 101 on the first current collector 11 of the outermost first electrode 10, the current density of the single-sided region can be reduced. At the same time, in conjunction with the pore formation of the first active layer 12, while achieving the above effects, the CB value of the single-sided region can also be improved, thus avoiding lithium plating in the single-sided region.

[0108] In some embodiments, see Figure 4 As shown, the outermost first electrode 10 is provided with two sets of first recesses 101 on the side facing the second electrode 20 along the first direction. The two sets of first recesses 101 are arranged opposite each other along the second direction. The size of a single set of first recesses 101 along the second direction is P mm, where P satisfies 1 / 15×L1≤P≤1 / 2×L1, where L1 is the size of the first electrode 10 along the second direction, and the unit of L1 is mm.

[0109] It should be noted that, Figure 4The recessed structure of the first electrode 10 located on the outermost layer is shown. The dimension of a single first recess 101 along the second direction is P mm. If P is too small, it is easy to cause insufficient electrolyte storage in the single-sided area, insignificant electrolyte wetting effect, and excessive current density in the single-sided area. Therefore, P needs to satisfy P≥1 / 15×L1. If P is too large, it is easy to cause excessive pores in the single-sided area, which can easily lead to loss of active material in the first electrode 10, reduce the capacity of the cell, and shorten the cycle life of the cell. Therefore, P also needs to satisfy P≤1 / 2×L1.

[0110] By creating two sets of first recesses 101 on the side of the outermost first electrode 10 facing the second electrode 20 along the first direction, the electrolyte storage capacity of the outermost first electrode 10 is increased and the wetting effect is improved. This avoids electrolyte loss due to expansion force in the outermost layer, while also increasing the CB value of the single-sided area, reducing the current density of the single-sided area, and solving the lithium plating problem in the single-sided area. The dimension P of a single set of first recesses 101 along the second direction satisfies 1 / 15×L1≤P≤1 / 2×L1, where L1 is the dimension of the first electrode 10 along the second direction. This not only ensures sufficient electrolyte storage capacity in the single-sided area, ensuring the electrolyte wetting effect, increasing the CB value of the single-sided area, effectively reducing the current density of the single-sided area, and solving the lithium plating problem in the single-sided area, but also prevents the loss of active material from the first electrode 10, ensuring the capacity of the battery cell and avoiding affecting the cycle life of the battery cell.

[0111] Preferably, P further satisfies 1 / 10×L1≤P≤1 / 4×L1.

[0112] In some embodiments, see Figure 4 As shown, the first recess 101 includes a plurality of first holes 1011, which are spaced apart on the first electrode 10 along the second direction and / or the third direction.

[0113] For the outermost first electrode 10, the projection of the first hole 1011 formed by the first current collector 11 along the first direction is all within the projection range of the first hole 1011 formed by the first active layer 12; the area of ​​a single first hole 1011 formed by the first current collector 11 is S1μm. 2 S1 satisfies 10% × S2 ≤ S1 ≤ 100% × S2, where S2 is the area of ​​a single first pore 1011 formed on the first active layer 12, and the unit of S2 is μm. 2 .

[0114] It should be noted that if the area S1 of the single first hole 1011 formed by the first current collector 11 is too small, the current density in the single-sided area cannot be effectively reduced, making it difficult to effectively solve the lithium plating problem in the single-sided area. Therefore, the area S1 of the single first hole 1011 formed by the first current collector 11 must satisfy S1≥10%×S2, where S2 is the area of ​​the single first hole 1011 formed on the first active layer 12. If the area S1 of the single first hole 1011 formed by the first current collector 11 is too large, it will not only easily lead to excessive loss of active material during the hole formation process, but also easily cause leakage of positive electrode coating material. Therefore, the area S1 of the single first hole 1011 formed by the first current collector 11 must also satisfy S1≤100%×S2.

[0115] The area S1 of a single first hole 1011 formed by the first current collector 11 satisfies 10%×S2≤S1≤100%×S2, where S2 is the area of ​​a single first hole 1011 formed on the first active layer 12. This not only effectively reduces the current density in the single-sided area and effectively solves the problem of lithium plating in the single-sided area, but also avoids excessive loss of active material during the hole formation process and prevents leakage of positive electrode coating material.

[0116] Preferably, S1 further satisfies 20%×S2≤S1≤80%×S2, where S2 is the area of ​​a single first pore 1011 formed on the first active layer 12.

[0117] In some embodiments, the total opening area of ​​the first recess 101 formed by the first current collector 11 is S3 mm. 2 S3 satisfies 1 / 1000×S4≤S3≤1 / 50×S4, where S4 is the total area of ​​the first current collector 11, and the unit of S4 is mm. 2 .

[0118] It should be noted that if the total open area S3 of the first recess 101 formed by the first current collector 11 is too small, it may lead to insufficient liquid storage space of the first electrode 10 and insufficient lithium ion transport path and diffusion rate. Therefore, S3 needs to satisfy S3≥1 / 1000×S4. If the total open area S3 of the first recess 101 formed by the first current collector 11 is too large, since the hole is formed before rolling, it may cause the first current collector 11 to break after rolling. If the first current collector 11 and the first active layer 12 are formed together, it may lead to excessive loss of active material during the hole formation process, resulting in excessive loss of battery capacity. Therefore, S3 also needs to satisfy S3≤1 / 50×S4, where S4 is the total area of ​​the first current collector 11.

[0119] The total opening area S3 of the first recess 101 formed by the first current collector 11 satisfies 1 / 1000×S4≤S3≤1 / 50×S4, where S4 is the total area of ​​the first current collector 11. This not only ensures sufficient liquid storage space for the first electrode 10, increases the transport path and diffusion rate of lithium ions, and improves the lithium deposition phenomenon of the electrode, but also avoids the breakage of the first current collector 11 after rolling, avoids excessive loss of active material during the hole formation process, and reduces battery capacity loss.

[0120] In some embodiments, see Figure 6 As shown, the pore size of the first pore 1011 formed by the first active layer 12 is D1, which satisfies 50μm≤D1≤1000μm. For example, D1 can take the value of 50μm, 500μm, 800μm or 1000μm; the pore spacing of the first pore 1011 formed by the first active layer 12 is B1, which satisfies 50μm≤B1≤5000μm. For example, B1 can take the value of 50μm, 500μm, 1000μm or 5000μm.

[0121] Please see Figure 5 As shown, the aperture of the first hole 1011 formed by the first current collector 11 is D2, which satisfies D2≤D1 and 10μmm≤D2≤500μmm. For example, D2 can take the value of 10μmm, 50μmm, 100μmm or 500μmm. The hole spacing of the first hole 1011 formed by the first current collector 11 is B2, which satisfies 50μm≤B2≤20000μm. For example, B2 can take the value of 50μm, 100μmm, 1000μmm, 10000μm or 20000μm.

[0122] It should be noted that for the first active layer 12, when the pore spacing is constant, if the pore size of the first pore 1011 is too large, it is easy to cause excessive loss of active material during the pore formation process, resulting in excessive battery capacity loss. Therefore, D1 must satisfy D1≤1000μm. If the pore size of the first pore 1011 is too small, it is easy to cause the liquid storage space of the first electrode 10 to be too small. Therefore, D1 must satisfy D1≥50μm. For the first active layer 12, when the pore size is constant, if the pore spacing of the first pore 1011 is too small, it is easy to cause the first pores 1011 to be set too densely, which is easy to cause excessive loss of active material during the pore formation process, resulting in excessive battery capacity loss. Therefore, B1 must satisfy B1≥50μm. If the pore spacing of the first pore 1011 is too large, it is easy to cause the liquid storage space of the first electrode 10 to be too small. Therefore, B1 must satisfy B1≤1000μm.

[0123] For the first current collector 11, when the hole spacing is constant, if the diameter of the first hole 1011 is too large, it may cause the first current collector 11 to break after rolling. Therefore, D2 needs to satisfy D2≤500μmm. If the diameter of the first hole 1011 is too small, the current density in the single-sided area cannot be effectively reduced, making it difficult to effectively solve the problem of lithium deposition in the single-sided area. Therefore, D2 needs to satisfy D2≥10μmm. For the first current collector 11, when the hole diameter is constant, if the hole spacing of the first hole 1011 is too small, it is easy to cause the first current collector 11 to break. Therefore, B2 needs to satisfy B2≥50μm. If the hole spacing of the first hole 1011 is too large, the current density in the single-sided area cannot be effectively reduced, making it difficult to effectively solve the problem of lithium deposition in the single-sided area. Therefore, B2 needs to satisfy B2≤20000μm.

[0124] This configuration not only ensures sufficient liquid storage space for the first electrode 10, but also prevents the first current collector 11 from breaking after rolling, avoids excessive loss of active material during the pore-forming process, reduces battery capacity loss, and effectively reduces the current density in the single-sided area, thus effectively solving the problem of lithium plating in the single-sided area.

[0125] In some embodiments, the first electrode 10 located in the inner layer is provided with a second recess 102.

[0126] By providing a first recess 101 on the outermost first electrode 10, the electrolyte storage capacity and wetting effect of the outermost first electrode 10 are increased, preventing electrolyte loss due to expansion force in the outermost layer. At the same time, the CB value of the single-sided area is increased, the current density of the single-sided area is reduced, and the lithium plating problem in the single-sided area is solved. Meanwhile, by providing a second recess 102 on the inner first electrode 10, the electrolyte storage capacity and wetting effect of the stacked core can be further increased, the CB value of the local area can be increased, and lithium plating in the local area can be avoided.

[0127] In some embodiments, see Figure 7 As shown, the first electrode 10 located in the inner layer includes a second current collector 14 and a second active layer 15. The second active layer 15 is located on both sides of the second current collector 14 in a first direction. The thickness of the second current collector 14 is H2, and the value of H2 is in the range of 7μm≤H2≤15μm. For example, H2 can be 7μm, 9μm, 13μm or 15μm.

[0128] The second active layer 15 is provided with a second recess 102, the depth of the second recess 102 being less than or equal to the thickness of the second active layer 15.

[0129] And / or, please see Figure 8As shown, the second recess 102 includes a plurality of second holes 1021. The distance between any second hole 1021 and the edge of the first electrode 10 is Q1, and Q1 satisfies 100μm≤Q1≤5000μm, thereby avoiding cutting the second hole 1021 exactly when the first electrode 10 is die-cut, and preventing burrs or powder from falling off the first electrode 10.

[0130] It should be noted that, since the thickness of the second current collector 14 located in the inner layer of the first electrode 10 is relatively thin, no holes are formed on the second current collector 14 located in the inner layer of the first electrode 10. After the second active layer 15 is coated to form the second active layer 15, holes are formed only in the second active layer 15 to form the second recess 102, so as to avoid the second current collector 14 from breaking. The holes in the second active layer 15 can be formed before rolling or after rolling.

[0131] For the first electrode 10 of the inner layer, a second recess 102 is formed by creating pores in the second active layer 15, thereby increasing the liquid storage capacity, increasing the CB value of the pore-forming area, and alleviating local lithium plating.

[0132] Preferably, the value of H2 is in the range of 8μm≤H2≤10μm.

[0133] It should be noted that if the distance Q1 between any second hole 1021 and the edge of the first electrode 10 is too small, the burrs will be large during die cutting and the edge lithium deposition will be severe. Therefore, Q1 must satisfy Q1≥100μm; if Q1 is too large, it will not effectively alleviate the edge lithium deposition. Therefore, Q1 must satisfy Q1≤5000μm.

[0134] In some embodiments, see Figure 9 As shown, a plurality of second holes 1021 are spaced around the edge region 121 of the second active layer 15; the distance between the second hole 1021 and the outer edge of the second active layer 15 is Q2, which satisfies 1000μm≤Q2≤5000μm. For example, Q2 can take the value of 1000μm, 2500μm, 4000μm or 5000μm. This can reduce burrs during die cutting and effectively alleviate edge lithium plating.

[0135] And / or, please see Figure 10 As shown, the second hole 1021 is disposed in the corner region 122 of the second active layer 15. The opening area S5 of each corner region 122 satisfies 0.5×S6≤S5≤S6, where S6 is the area of ​​a single corner region 122, and the units of S5 and S6 are both mm. 2 S6 = a × a, where the value of a ranges from 1 / 10 × L1 ≤ a ≤ 1 / 8 × L1, and L1 is the dimension of the first electrode 10 along the second direction. The units of a and L1 are both mm. This can alleviate lithium plating at the corner and avoid cell capacity loss.

[0136] And / or, please see Figure 11 As shown, the second hole 1021 is disposed in the central region 123 of the second active layer 15. The opening area S7 of the central region 123 satisfies 0.1×S4≤S7≤0.5×S4, where S4 is the total area of ​​the second current collector 14, and the units of S7 and S4 are both mm. 2 This can alleviate the black spots in the middle and avoid causing a loss of cell capacity.

[0137] It should be noted that if the distance Q2 between the second hole 1021 and the outer edge of the second active layer 15 in the edge region 121 of the first electrode 10 in the inner layer is too small, the burrs during die cutting will be relatively large, and the edge lithium plating will be severe. Therefore, Q2 needs to satisfy Q2≥1000μm; if Q2 is too large, the effect of alleviating edge lithium plating will not be obvious. Therefore, Q2 needs to satisfy Q2≤5000μm. In the corner regions 122 of the first electrode 10 in the inner layer, if the opening area S5 of each corner region 122 is too small, the wetting effect of the corner region 122 will not be obvious. Therefore, S5 needs to satisfy S5≥0.5×S6; if S5 is too large, it will easily cause cell capacity loss. Therefore, S5 needs to satisfy S5≤S6. In the central region 123 of the first electrode 10 in the inner layer, if the opening area S7 of the central region 123 is too small, it will easily lead to an insignificant wetting effect in the middle of the electrode and will not be able to effectively alleviate the black spots in the middle of the electrode. Therefore, S7 needs to satisfy S7≥0.1×S4. If the opening area S7 of the central region 123 is too large, it will easily cause a loss of cell capacity. Therefore, S7 needs to satisfy 0.5×S4, where S4 is the total area of ​​the second current collector 14.

[0138] In some embodiments, see Figure 13 and Figure 14 As shown, the second electrode 20 is provided with a third recess 201, thereby improving the lithium intercalation capability of the negative electrode, reducing the lithium intercalation detour, improving the electrolyte wetting capability, and mitigating the lithium desorption problem.

[0139] In some embodiments, see Figure 12 As shown, the second electrode 20 includes a third current collector 21 and a third active layer 22, with the third active layer 22 located on both sides of the third current collector 21 in a first direction;

[0140] The third active layer 22 is provided with a third recess 201 to prevent the third current collector 21 from breaking; the depth of the third recess 201 of the third active layer 22 is less than or equal to the thickness of the third active layer 22.

[0141] For the second electrode 20, a third recess 201 is formed by creating pores in the third active layer 22, thereby improving the lithium intercalation capability of the negative electrode, reducing the lithium intercalation detour, improving electrolyte wetting, and mitigating the lithium desorption problem.

[0142] In some embodiments, see Figure 13 As shown, the third recess 201 includes a plurality of third holes 2011. The distance between any third hole 2011 and the outer edge of the second electrode 20 is Q3, which satisfies 100μm≤Q3≤5000μm. For example, Q3 can take the values ​​of 100μm, 1000μm, 4000μm or 5000μm.

[0143] It should be noted that if the distance Q3 between any third hole 2011 and the outer edge of the second electrode 20 is too small, the burrs will be large during die cutting and the edge lithium plating will be severe. Therefore, Q3 must satisfy Q3≥100μm; if Q3 is too large, it will not effectively alleviate the edge lithium plating. Therefore, Q3 must satisfy Q3≤5000μm.

[0144] Preferably, the value range of Q3 can be further 500μm≤Q1≤2000μm.

[0145] In some embodiments, see Figure 14 As shown, the third recess 201 includes a plurality of grooves 2012, which are spaced apart along a third direction; the width of the groove 2012 is T, which satisfies 20μm≤T≤500μm. For example, T can take the value of 20μm, 100μm, 400μm or 500μm; the distance between two adjacent grooves 2012 is Q4, which satisfies 200μm≤Q4≤3000μm. For example, Q4 can take the value of 200μm, 500μm, 1000μm or 3000μm.

[0146] It should be noted that, for the third active layer 22, when the spacing of the grooves 2012 is constant, if the width T of the grooves 2012 is too large, it is easy to cause excessive loss of active material during the pore formation process, resulting in excessive battery capacity loss. Therefore, T needs to satisfy T≤500μm; if T is too small, it is easy to cause the liquid storage space of the second electrode 20 to be too small. Therefore, T needs to satisfy T≥20μm. For the third active layer 22, when the width of the grooves 2012 is constant, if the spacing of the grooves 2012 is too small, it is easy to cause excessive loss of active material during the pore formation process, resulting in excessive battery capacity loss. Therefore, Q4 needs to satisfy Q4≥200μm; if the spacing of the grooves 2012 is too large, it is easy to cause the liquid storage space of the second electrode 20 to be too small. Therefore, Q4 needs to satisfy Q4≤3000μm.

[0147] Furthermore, the depth of the groove 2012 is less than or equal to the thickness of the third active layer 22.

[0148] Preferably, T satisfies 50μm≤T≤200μm, and Q4 satisfies 500μm≤Q4≤2000μm.

[0149] In some embodiments, the areal density of the outermost first electrode 10 is less than or equal to the areal density of the inner first electrode 10, thereby reducing the current density of the outermost first electrode 10 and solving the problem of lithium deposition on one side.

[0150] In some embodiments, see Figure 15 As shown, the total bonding area between each first electrode 10 and the second adhesive portion 402 is S8, where S8 satisfies 1 / 10×S4≤S8≤4 / 10×S4, and S4 is the total area of ​​the first current collector 11. The units of S8 and S4 are both mm. 2 .

[0151] It should be noted that if the total bonding area S8 between each first electrode 10 and the second bonding part 402 is too small, the bonding force may be too weak, and the electrode may not be able to effectively prevent delamination or scattering. Therefore, S8 needs to satisfy S8≥1 / 10×S4, where S4 is the total area of ​​the first current collector 11. If S8 is too large, it may cause poor electrolyte wetting. Therefore, S8 needs to satisfy S8≤4 / 10×S4.

[0152] Furthermore, the adhesive tape 40 can be made of biaxially oriented polypropylene film, high-temperature resistant polyester film, or polyimide film; the adhesive can be acrylate adhesive or rubber adhesive.

[0153] In some embodiments, see Figure 15 As shown, the bonding width between each first electrode 10 and the second bonding part 402 is W1, and the value of W1 is in the range of 4mm≤W1≤20mm. For example, W1 can be 4mm, 10mm, 15mm or 20mm. The bonding dimension of the first bonding part 401 along the first direction is J, and J satisfies 0.5mm≤J≤2mm. For example, J can be 0.5mm, 1mm or 2mm. This ensures sufficient bonding force, effectively prevents electrode delamination or scattering, improves cell safety, and avoids poor electrolyte wetting.

[0154] In some embodiments, the adhesive tape 40 includes a first adhesive tape 41, wherein the first adhesive tape 41 is... Figures 16-19 The non-porous adhesive tape shown;

[0155] Please see Figure 16 As shown, the first adhesive tape 41 is pasted on both sides of the third direction of the first electrode 10. The total bonding length of the first adhesive tape 41 along the second direction is K1 mm. K1 satisfies 1 / 2×L1≤K1≤4 / 5×L1. L1 is the dimension of the first electrode 10 along the second direction, and the unit of L1 is mm.

[0156] And / or, a first electrode tab 13 extends from one side of the first electrode 10 in the second direction, and a second electrode tab 23 extends from one side of the second electrode 20 in the second direction. The second electrode tab 23 and the first electrode tab 13 are spaced apart from each other in the third direction. A first adhesive tape 41 is pasted on the side of the first electrode 10 in the second direction close to the first electrode tab 13. The size of the first adhesive tape 41 in the third direction is K2mm. K2 satisfies 1 / 2×L2≤K2≤4 / 5×L2. L2 is the distance between the first electrode tab 13 and the second electrode tab 23 in the third direction. The unit of L2 is mm.

[0157] And / or, the first adhesive tape 41 is pasted on the side of the first electrode 10 away from the first electrode tab 13 along the second direction. The dimension of the first adhesive tape 41 along the third direction is K3 mm. K3 satisfies 1 / 2×L3≤K3≤4 / 5×L3. L3 is the dimension of the first electrode 10 along the third direction. The unit of L3 is mm.

[0158] By employing the first adhesive tape 41, the adhesive tape 40 ensures a sufficient covering area on the stacked core, thereby ensuring sufficient adhesion, effectively preventing electrode delamination or scattering, improving stacked core stability, and enhancing process yield and safety. Simultaneously, by providing a first recess 101 on the outermost first electrode 10, a second recess 102 on the inner first electrode 10, and / or a third recess 201 on the second electrode 20, wettability is improved in conjunction with positive or negative electrode pore formation, while mitigating lithium desorption issues.

[0159] In some embodiments, the adhesive tape 40 includes a second adhesive tape 42, wherein the second adhesive tape 42 is... Figures 20-22 The perforated adhesive tape shown;

[0160] Please see Figure 20 As shown, the second adhesive tape 42 is pasted on both sides of the third direction of the first electrode 10. The total bonding length of the second adhesive tape 42 along the second direction is K4 mm. K4 satisfies 1 / 2×L1≤K4≤L1, where L1 is the dimension of the first electrode 10 along the second direction, and the unit of L1 is mm.

[0161] And / or, a first electrode tab 13 extends from one side of the first electrode 10 in the second direction, and a second electrode tab 23 extends from one side of the second electrode 20 in the second direction. The second electrode tab 23 and the first electrode tab 13 are spaced apart from each other in the third direction. A second adhesive tape 42 is pasted on the side of the first electrode 10 in the second direction close to the first electrode tab 13. The size of the second adhesive tape 42 in the third direction is K5mm. K5 satisfies 1 / 2×L2≤K5≤4 / 5×L2. L2 is the distance between the first electrode tab 13 and the second electrode tab 23 in the third direction. The unit of L2 is mm.

[0162] And / or, the second adhesive tape 42 is pasted on the side of the first electrode 10 away from the first electrode tab 13 along the second direction. The dimension of the second adhesive tape 42 along the third direction is K6 mm. K6 satisfies 1 / 2×L3≤K6≤L3. L3 is the dimension of the first electrode 10 along the third direction. The unit of L3 is mm.

[0163] By employing the second adhesive tape 42, not only is the coverage area of ​​the adhesive tape 40 on the stacked core ensured, thereby ensuring sufficient adhesion and effectively preventing electrode delamination or scattering, thus improving the stability of the stacked core, process yield, and safety, but the second adhesive tape 42 is also a porous adhesive tape, which facilitates electrolyte wetting. At the same time, by providing a first recess 101 on the outermost first electrode 10, a second recess 102 on the inner first electrode 10, and / or a third recess 201 on the second electrode 20, wettability is improved in conjunction with positive or negative electrode pore formation, while mitigating lithium desorption issues.

[0164] According to an embodiment of the present invention, another aspect provides a lithium-ion secondary battery, comprising: a packaging shell, and a stacked core as described above, wherein the packaging shell has a receiving cavity, and the stacked core is housed within the receiving cavity.

[0165] The lithium-ion secondary battery in this embodiment includes the above-described stacked core, and therefore, the lithium-ion secondary battery in this embodiment includes all the beneficial effects of the above-described stacked core.

[0166] Referring to Table 1 below, the following test examples verify the stacking stability and single-sided lithium deposition problem of the secondary battery provided by the embodiments of this utility model. The secondary battery uses the first adhesive paper 41.

[0167] Table 1

[0168]

[0169] It should be noted that when the values ​​of P, K1, K2, or K3 are higher than the upper limit, it will affect the process yield and efficiency, so it will no longer be verified through specific experiments.

[0170] As shown in Table 1, P can solve the single-sided lithium plating problem and ensure the cell capacity by satisfying 1 / 15×L1≤P≤1 / 2×L1.

[0171] As shown in Table 1, the secondary battery uses the first adhesive paper 41, K1 satisfies 1 / 2×L1≤K1≤4 / 5×L1, and / or K2 satisfies 1 / 2×L2≤K2≤4 / 5×L2, and / or K3 satisfies 1 / 2×L3≤K3≤4 / 5×L3, which can effectively prevent electrode delamination and improve the stability of the stacked core.

[0172] Referring to Table 2 below, the following test examples verify the stacking stability of the secondary battery provided by the embodiments of this utility model, wherein the secondary battery uses the second adhesive paper 42.

[0173] Table 2

[0174] Serial Number <![CDATA[L1 / mm]]> <![CDATA[L2 / mm]]> <![CDATA[L3 / mm]]> <![CDATA[K4 / mm]]> <![CDATA[K5 / mm]]> <![CDATA[K6 / mm]]> <![CDATA[S4 / mm 2 ]]> Is the core layered? Example 4 78 20 61 60 13 46 4758 No layering Example 5 78 20 61 60 13 46 4758 No layering Example 6 78 20 61 60 13 46 4758 No layering Comparative Example 4 78 20 61 60 13 46 4758 No layering Comparative Example 5 78 20 61 60 13 46 4758 No layering Comparative Example 6 78 20 61 25 6 22 4758 Layering

[0175] It should be noted that when the values ​​of K4, K5, or K6 are higher than the upper limit, it will affect the process yield and efficiency, so it will no longer be verified through specific experiments.

[0176] As shown in Table 2, the secondary battery uses the second adhesive paper 42. K4 satisfies 1 / 2×L1≤K4≤L1, and / or K5 satisfies 1 / 2×L2≤K5≤4 / 5×L2, and / or K6 satisfies 1 / 2×L3≤K6≤L3, which can effectively prevent electrode delamination and improve the stability of the stacked core.

[0177] Referring to Table 3 below, the following sets of test examples verify the lithium plating problem and battery capacity of the secondary battery provided by the embodiments of this utility model.

[0178] Table 3

[0179]

[0180] It should be noted that when the values ​​of S3, S5, or S7 are higher than the upper limit, it will affect the process yield and efficiency, so it will no longer be verified through specific experiments.

[0181] As shown in Table 3, S3, by satisfying 1 / 1000×S4≤S3≤1 / 50×S4, can improve the lithium plating phenomenon on the electrode and reduce the cell capacity loss. S5, by satisfying 0.5×S6≤S5≤S6, where S6=a×a, and the value of a is in the range of 1 / 10×L1≤a≤1 / 8×L1, can alleviate corner lithium plating and reduce the cell capacity loss. S7, by satisfying 0.1×S4≤S7≤0.5×S4, can alleviate the central black spot and reduce the cell capacity loss.

[0182] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A core stack, characterized in that The application relates to a battery electrode plate, which comprises: a first electrode plate (10); a second electrode plate (20) arranged in layers with the first electrode plate (10), the second electrode plate (20) being arranged between every two adjacent layers of the first electrode plate (10), and a diaphragm (30) being arranged between the second electrode plate (20) and the first electrode plate (10); the first electrode plate (10) on the outermost layer is provided with a first recess (101); a gummed paper (40) comprising a first adhesive part (401) and a second adhesive part (402), the first adhesive part (401) being connected with the outer edge of the diaphragm (30) in the third direction, and the side of the first electrode plate (10) on the outermost layer away from the second electrode plate (20) in the first direction being adhered to the second adhesive part (402).

2. The laminated core of claim 1, wherein The first electrode plate (10) on the outermost layer comprises a first current collector (11) and a first active layer (12), the first active layer (12) being arranged on the side of the first current collector (11) facing the second electrode plate (20) in the first direction; the first current collector (11) and the first active layer (12) are both provided with the first recess (101), and the orthographic projection of the first recess (101) on the first current collector (11) at least partially overlaps the orthographic projection of the first recess (101) on the first active layer (12).

3. The laminated core of claim 2 wherein, The depth of the first recess (101) of the first current collector (11) is less than or equal to the thickness of the first current collector (11), the thickness of the first current collector (11) being H1, and the value range of H1 is 10 mu m <= H1 <= 30 mu m; the depth of the first recess (101) of the first active layer (12) is less than or equal to the total thickness of the first electrode plate (10).

4. The laminated core of claim 2 wherein, The side of the first electrode plate (10) on the outermost layer facing the second electrode plate (20) in the first direction is provided with two groups of first recesses (101), the two groups of first recesses (101) being oppositely arranged in the second direction, the size of a single group of first recesses (101) in the second direction being P mm, and P satisfies 1 / 15*L1 <= P <= 1 / 2*L1, wherein L1 is the size of the first electrode plate (10) in the second direction, and the unit of L1 is mm.

5. The core according to claim 4, wherein The first recess (101) comprises a plurality of first holes (1011), and the plurality of first holes (1011) are arranged at intervals in the second direction and / or the third direction on the first electrode plate (10); The projections of the first holes (1011) formed by the first current collector (11) along the first direction are all located within the projection range of the first holes (1011) formed by the first active layer (12); the area of a single first hole (1011) formed by the first current collector (11) is S1 μm 2 , and S1 satisfies 10% × S2 ≤ S1 ≤ 100% × S2, wherein S2 is the area of a single first hole (1011) formed on the first active layer (12), and the unit of S2 is μm 2 .

6. The core according to claim 5, wherein The total open area of the first recess (101) formed by the first current collector (11) is S3 mm 2 S3 satisfies 1 / 1000×S4≤S3≤1 / 50×S4, where S4 is the total area of the first current collector (11), and the unit of S4 is mm 2 .

7. The laminated core of claim 5 wherein, The aperture of the first hole (1011) formed by the first active layer (12) is D1, and D1 satisfies 50 mu m <= D1 <= 1000 mu m; the hole spacing of the first hole (1011) formed by the first active layer (12) is B1, and B1 satisfies 50 mu m <= B1 <= 5000 mu m; The aperture of the first hole (1011) formed by the first current collector (11) is D2, and D2 satisfies D2 <= D1 and 10 mu mm <= D2 <= 500 mu mm; the hole spacing of the first hole (1011) formed by the first current collector (11) is B2, and B2 satisfies 50 mu m <= B2 <= 20000 mu m.

8. The laminated core of claim 1 wherein, The first pole piece (10) located in the inner layer is provided with a second recess (102).

9. The laminated core of claim 8, wherein The first pole piece (10) located in the inner layer comprises a second current collector (14) and a second active layer (15), and the second active layer (15) is located on both sides of the first direction of the second current collector (14); the thickness of the second current collector (14) is H2, and H2 satisfies 7μm≤H2≤15μm. The second active layer (15) is provided with the second recess (102), and the depth of the second recess (102) is less than or equal to the thickness of the second active layer (15). And / or, the second recess (102) comprises a second hole (1021), and the distance between the second hole (1021) and the edge of the first pole piece (10) is Q1, Q1 satisfies 100μm≤Q1≤5000μm.

10. The laminated core of claim 9, wherein A plurality of second holes (1021) are arranged at intervals around the edge area (121) of the second active layer (15); the distance between the second hole (1021) and the outer edge of the second active layer (15) is Q2, Q2 satisfies 1000μm≤Q2≤5000μm. And / or, the second hole (1021) is arranged at a corner area (122) of the second active layer (15), the opening area S5 of each corner area (122) satisfies 0.5×S6≤S5≤S6, S6 is the area of a single corner area (122), and the units of S5 and S6 are both mm 2 The length of a single corner area (122) is a, and the value range of a is 1 / 10×L1≤a≤1 / 8×L1, L1 is the size of the first pole piece (10) in the second direction, and the units of a and L1 are both mm. And / or, the second hole (1021) is arranged in a center region (123) of the second active layer (15), an open area S7 of the center region (123) satisfies 0.1xS4≤S7≤0.5xS4, S4 is a total area of the second current collector (14), units of S7 and S4 are both mm 2 .

11. The laminated core of any of claims 1-10, wherein, The second pole piece (20) is provided with a third recess (201).

12. The laminated core of claim 11, wherein, The second pole piece (20) comprises a third current collector (21) and a third active layer (22), and the third active layer (22) is located on both sides of the first direction of the third current collector (21). The third active layer (22) is provided with the third recess (201); and the depth of the third recess (201) is less than or equal to the thickness of the third active layer (22).

13. The laminated core of claim 12, wherein, The third recess (201) comprises a plurality of third holes (2011), and the distance between any one of the third holes (2011) and the outer edge of the second pole piece (20) is Q3, Q3 satisfies 100μm≤Q3≤5000μm.

14. The laminated core of claim 12 wherein, The third recess (201) comprises a plurality of grooves (2012), and a plurality of the grooves (2012) are arranged at intervals along the third direction; the width of the groove (2012) is T, T satisfies 20μm≤T≤500μm; the distance between adjacent two grooves (2012) is Q4, Q4 satisfies 200μm≤Q4≤3000μm.

15. The core according to claim 2, wherein The areal density of the first pole piece (10) located in the outermost layer is less than or equal to the areal density of the first pole piece (10) located in the inner layer.

16. The core according to claim 15, wherein The total bonding area between each of the first pole pieces (10) and the second bonding portion (402) is S8, S8 satisfies 1 / 10×S4≤S8≤4 / 10×S4, wherein S4 is the total area of the first current collector (11), and the units of S8 and S4 are both mm 2 .

17. The laminated core of claim 16 wherein, The bonding width between each of the first pole pieces (10) and the second bonding part (402) is W1, and W1 satisfies 4mm≤W1≤20mm; and the bonding size of the first bonding part (401) along the first direction is J, J satisfies 0.5mm≤J≤2mm.

18. The core according to claim 17, wherein, The adhesive paper (40) comprises a first adhesive paper (41), and the first adhesive paper (41) is a non-porous adhesive paper. The first adhesive tape (41) is attached to both sides of the first tab (10) in the third direction, and the total length of the first adhesive tape (41) in the second direction is K1 mm, K1 satisfies 1 / 2*L1≤K1≤4 / 5*L1, L1 is the size of the first tab (10) in the second direction, and the unit of L1 is mm; And / or, the first tab (10) extends a first lug (13) on one side in the second direction, the second tab (20) extends a second lug (23) on one side in the second direction, and the second lug (23) is arranged opposite to the first lug (13) in the third direction; the first adhesive tape (41) is attached to one side of the first tab (10) close to the first lug (13) in the second direction, and the size of the first adhesive tape (41) in the third direction is K2 mm, K2 satisfies 1 / 2*L2≤K2≤4 / 5*L2, L2 is the distance between the first lug (13) and the second lug (23) in the third direction, and the unit of L2 is mm; And / or, the first adhesive tape (41) is attached to one side of the first tab (10) away from the first lug (13) in the second direction, and the size of the first adhesive tape (41) in the third direction is K3 mm, K3 satisfies 1 / 2*L3≤K3≤4 / 5*L3, L3 is the size of the first tab (10) in the third direction, and the unit of L3 is mm.

19. The core according to claim 17, wherein The adhesive tape (40) comprises a second adhesive tape (42), and the second adhesive tape (42) is a perforated adhesive tape; The second adhesive tape (42) is attached to both sides of the first tab (10) in the third direction, and the total length of the second adhesive tape (42) in the second direction is K4 mm, K4 satisfies 1 / 2*L1≤K4≤L1, L1 is the size of the first tab (10) in the second direction, and the unit of L1 is mm; And / or, the first tab (10) extends a first lug (13) on one side in the second direction, the second tab (20) extends a second lug (23) on one side in the second direction, and the second lug (23) is arranged opposite to the first lug (13) in the third direction; the second adhesive tape (42) is attached to one side of the first tab (10) close to the first lug (13) in the second direction, and the size of the second adhesive tape (42) in the third direction is K5 mm, K5 satisfies 1 / 2*L2≤K5≤4 / 5*L2, L2 is the distance between the first lug (13) and the second lug (23) in the third direction, and the unit of L2 is mm; And / or, the second adhesive tape (42) is attached to one side of the first tab (10) away from the first lug (13) in the second direction, and the size of the second adhesive tape (42) in the third direction is K6 mm, K6 satisfies 1 / 2*L3≤K6≤L3, L3 is the size of the first tab (10) in the third direction, and the unit of L3 is mm.

20. A lithium-ion secondary battery, characterized by comprising: Comprise: A packaging shell, and the core stack of any one of claims 1 to 19; A packaging shell, and the core stack of any one of claims 1 to 19; The packaging case has a housing cavity, and the core is built in the housing cavity.

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