Pole piece and battery

Abstract

The utility model relates to the technical field of battery energy, in particular to a pole piece and a battery. The pole piece comprises a current collector, a first active substance layer and a second active substance layer, a first concave part is formed on one surface of the first active substance layer, and a first convex part is formed on the other surface; a second concave part is formed on one surface of the current collector, and a second convex part is formed on the other surface; the first sunken part can store more electrolyte and can increase the contact area between the electrolyte and the first active material layer, and the bulges and the sunken parts formed between the current collector and the first active material layer can increase the infiltration channels of the electrolyte, so that the complete infiltration of the electrolyte is facilitated, and the effect of improving the ion transmission capability is achieved; and meanwhile, the problem of stress concentration in the charging and discharging processes can be solved by the bulges and the recesses formed by the current collector, the cycle performance of the battery is improved, and the service life of the battery can be prolonged.

Description

Technical Field

[0001] The present application relates to the field of battery energy technology, and in particular to a pole piece and a battery. Background Art

[0002] With the rapid development of battery technology, people have put forward higher requirements on battery energy density, fast charging capability and charge and discharge rate. High energy density fast charging lithium battery is also the development trend of consumer batteries.

[0003] At present, when manufacturing some battery cells, the positive electrode sheet, separator and negative electrode sheet are stacked together, and then wound from the head to the tail with the head of the negative electrode sheet as the center. In order to improve the energy density of the battery, the electrode sheet is gradually developing in the direction of high compaction and thick electrode.

[0004] However, in current thick electrode and high-density battery, it is difficult for the electrolyte to completely infiltrate the active material layer of the electrode. After continuous high-rate fast charging, the battery is prone to lithium deposition, which greatly affects the battery's rate, endurance, life and cycle performance. Utility Model Content

[0005] Based on this, the present application provides a pole piece and a battery to solve the lithium plating problem in the related technology and improve the cycle performance and life of the battery.

[0006] In one aspect, the present application provides a pole piece, comprising a current collector, a first active material layer and a second active material layer, wherein the first active material layer and the second active material layer are respectively located on opposite sides of the current collector in a thickness direction;

[0007] A first concave portion is formed on a side of the first active material layer away from the current collector, and a first convex portion is formed on a side of the first active material layer close to the current collector, wherein the first convex portion and the first concave portion are arranged opposite to each other;

[0008] A second recessed portion is formed on one side of the current collector close to the first active material layer, and the second recessed portion and the first protruding portion are arranged oppositely. A second protruding portion is formed on one side of the current collector close to the second active material layer, and the second protruding portion and the second recessed portion are arranged oppositely.

[0009] In a possible implementation manner, a third recessed portion is formed on a surface of the second active material layer close to the current collector, and the third recessed portion and the second protruding portion are arranged opposite to each other.

[0010] In a possible implementation manner, the first protruding portion and the second recessed portion are interlocked with each other, and / or the second protruding portion and the third recessed portion are interlocked with each other.

[0011] In a possible implementation, the aperture of the first recessed portion is D1, the aperture of the second recessed portion is D2, and the aperture of the third recessed portion is D3, and D1, D2, and D3 satisfy: D3≤D2≤D1;

[0012] And / or, D1 satisfies: 1mm≤D1≤5mm;

[0013] And / or, D2 satisfies: 1mm≤D2≤5mm;

[0014] And / or, D3 satisfies: 1mm≤D3≤5mm.

[0015] In a possible implementation, the hole spacing between the first recessed portions is W1, the hole spacing between the second recessed portions is W2, and the hole spacing between the third recessed portions is W3, and W1 satisfies: W1 ≥ 1.2 times D1;

[0016] and / or, W2 satisfies: W2 ≥ 1.2 times D2;

[0017] And / or, W3 satisfies: W3 ≥ 1.2 times D3.

[0018] In a possible implementation, the hole depth of the first recessed portion is L1, the hole depth of the second recessed portion is L2, and the hole depth of the third recessed portion is L3, and L1, L2 and L3 satisfy: L3≤L2≤L1;

[0019] And / or, L1 satisfies: 10um≤L1≤180um;

[0020] And / or, L2 satisfies: 10um≤L2≤180um;

[0021] And / or, L3 satisfies: 10um≤L3≤180um.

[0022] In a possible implementation, the pole piece includes a double-sided area, a single-sided area and an empty foil area, the double-sided area is an area where the first active material layer and the second active material layer exist on both sides of the current collector, the single-sided area is an area where the first active material layer or the second active material layer exists on only one side of the current collector, the empty foil area is an area where only the current collector exists, and the double-sided area is formed with a first recessed portion and a second recessed portion; and / or

[0023] The empty foil area is formed with a second concave portion and a second convex portion.

[0024] In a possible implementation manner, the third recessed portion is formed in the double-sided region; and / or the second active material layer in the single-sided region.

[0025] In a possible implementation, the first recessed portion, the first protruding portion, the second recessed portion, the second protruding portion and the third recessed portion are respectively distributed in an orderly array on the pole piece; and / or

[0026] The first recessed portion, the first protruding portion, the second recessed portion, the second protruding portion and the third recessed portion are respectively distributed on the entire surface or the edge of the pole piece.

[0027] On the other hand, the present application provides a battery, including a battery casing and a battery cell, the battery cell including the above-mentioned pole piece, and the battery cell is located in the battery casing.

[0028] The pole piece and battery provided by the present application have a first recessed portion that can store more electrolyte, and the contact area between the electrolyte and the first active material layer can also be increased through the first recessed portion. The electrolyte can infiltrate the interior of the first active material layer through the first recessed portion, and the protrusions and recesses formed between the current collector and the first active material layer can increase the infiltration channel of the electrolyte, which is convenient for complete infiltration of the electrolyte, thereby achieving the effect of improving the ion transmission capacity, thereby reducing the problem of lithium precipitation in the pole piece during the charging and discharging process of the battery. At the same time, the protrusions and recesses formed by the current collector can effectively disperse the stress on the current collector or the active material layer during the charging and discharging process, avoid stress concentration, reduce damage caused by volume changes during the charging and discharging process, improve the battery cycle performance, and at the same time increase the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 One of the structural schematic diagrams of the pole piece provided in the embodiment of the present application;

[0031] Figure 2 for Figure 1 A schematic cross-sectional view of the pole piece shown;

[0032] Figure 3 The second schematic diagram of the structure of the pole piece provided in the embodiment of the present application;

[0033] Figure 4 for Figure 3 A schematic cross-sectional view of the pole piece shown;

[0034] Figure 5 A schematic diagram of the structure of the first active material layer of the electrode provided in an embodiment of the present application;

[0035] Figure 6 for Figure 5 An enlarged structural schematic diagram of the first active material layer is shown;

[0036] Figure 7A schematic diagram of the structure of the current collector of the pole piece provided in an embodiment of the present application;

[0037] Figure 8 for Figure 7 An enlarged structural schematic diagram of the current collector shown;

[0038] Fig. 9 A schematic diagram of the structure of the second active material layer of the electrode provided in an embodiment of the present application;

[0039] Fig.10 for Fig. 9 An enlarged structural schematic diagram of the second active material layer is shown;

[0040] Fig.11 A schematic diagram of processing a pole piece provided in an embodiment of the present application;

[0041] Fig.12 One of the structural schematic diagrams of orderly printing on the electrode provided in the embodiment of the present application;

[0042] Fig.13 This is the second structural schematic diagram of the orderly printing on the electrode provided in the embodiment of the present application.

[0043] Description of reference numerals:

[0044] 100-pole piece; 10-current collector; 11-second recessed portion; 12-second protruding portion; 13-second flat portion; 20-first active material layer; 21-first recessed portion; 22-first protruding portion; 23-first flat portion; 30-second active material layer; 31-third recessed portion; 32-third flat portion; 40-double-sided area; 50-single-sided area; 60-empty foil area; 200-embossing roller; 300-fixing roller. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiment of the present application will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals throughout represent the same or similar parts or parts with the same or similar functions. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. The embodiments of the present application are described in detail below in conjunction with the drawings.

[0046] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0047] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are orientations or positional relationships based on the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0048] The terms "first", "second" and "third" (if any) in the specification and claims of this application and the above drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0049] In addition, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or display comprising a series of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such process, method, product, or display.

[0050] In the prior art, when the electrolyte infiltrates into the interior of the active material layer, the electrolyte infiltrates from the side of the active material layer away from the current collector to the side of the active material layer close to the current collector through the gaps between the particles in the active material layer. However, with the rapid development of batteries, people have higher and higher requirements for their rate, safety, life, and battery life. The pole piece is gradually developing in the direction of high compaction and thick electrodes, that is, the thickness of the active material layer on the pole piece is thicker and the compaction degree of the active material layer is higher. It is difficult for the electrolyte to completely infiltrate the active material layer of the pole piece. After continuous high-rate fast charging, the battery is prone to lithium precipitation, which greatly affects the battery's rate, battery life, life and cycle performance.

[0051] After repeated thinking and verification, the inventor found that if grooves are pressed out on the pole piece by embossing, and protrusions and depressions are formed between the layers of the pole piece, the grooves on the surface of the pole piece can store more electrolyte, and the contact area between the electrolyte and the active material layer can be increased through the grooves. The electrolyte can infiltrate the inside of the active material layer through the grooves, and the protrusions and depressions formed between the layers can increase the infiltration channel of the electrolyte, which is convenient for the complete infiltration of the electrolyte, and the electrolyte stored in the grooves of the empty foil area can flow to the head and tail parts, and then replenish into the inside of the pole piece. By setting the shape and spacing of the embossing, the area of ​​the groove wall is increased, and it is further convenient for the electrolyte to infiltrate the inside of the active material layer, so as to achieve the effect of improving the ion transmission capacity, thereby reducing the problem of lithium precipitation of the pole piece during the battery charging and discharging process. At the same time, the protrusions and depressions formed by the current collector can effectively disperse the stress on the current collector or the active material layer during the charging and discharging process, avoid stress concentration, reduce the damage caused by volume change during the charging and discharging process, improve the battery cycle performance, and at the same time, increase the service life of the battery.

[0052] In view of this, the utility model provides a pole piece, including a current collector, a first active material layer and a second active material layer, the first active material layer and the second active material layer are respectively located on opposite sides of the current collector in the thickness direction, a first recessed portion is formed on a side of the first active material layer away from the current collector, a first protruding portion is formed on a side of the first active material layer close to the current collector, and the first protruding portion and the first recessed portion are arranged oppositely; a second recessed portion is formed on a side of the current collector close to the first active material layer, the second recessed portion and the first protruding portion are arranged oppositely, a second protruding portion is formed on a side of the current collector close to the second active material layer, and the second protruding portion and the second recessed portion are arranged oppositely.

[0053] The first recessed portion can store more electrolyte, and the contact area between the electrolyte and the first active material layer can be increased through the first recessed portion. The electrolyte can infiltrate the interior of the first active material layer through the first recessed portion, and the protrusions and depressions formed between the current collector and the first active material layer can increase the infiltration channel of the electrolyte, which is convenient for the complete infiltration of the electrolyte. By embossing, the first recessed portion, the first protrusion, the second recessed portion, the second protrusion and the third recessed portion can be obtained. By setting the shape and spacing of the embossing, the area of ​​the groove wall is increased, which further facilitates the electrolyte to infiltrate the interior of the active material layer, so as to achieve the effect of improving the ion transmission capacity, thereby reducing the problem of lithium precipitation of the pole piece during the battery charging and discharging process. At the same time, the protrusions and depressions formed by the current collector can effectively disperse the stress on the current collector or the active material layer during the charging and discharging process, avoid stress concentration, reduce the damage caused by volume change during the charging and discharging process, improve the battery cycle performance, and at the same time, increase the service life of the battery.

[0054] The content of the utility model will be described in detail below with reference to the accompanying drawings so that those skilled in the art can understand the content of the utility model more clearly and in detail.

[0055] Figure 1 This is one of the schematic diagrams of the structure of the pole piece provided in the embodiment of the present application. Figure 2 for Figure 1 The cross-sectional diagram of the pole piece shown, Figure 3 The second schematic diagram of the structure of the pole piece provided in the embodiment of the present application is as follows: Figure 4 for Figure 3 The cross-sectional diagram of the pole piece shown, Figure 5 A schematic diagram of the structure of the first active material layer of the electrode provided in an embodiment of the present application, Figure 6 for Figure 5 The enlarged structural diagram of the first active material layer is shown in FIG. Figure 7 A schematic diagram of the structure of the current collector of the pole piece provided in the embodiment of the present application, Figure 8 for Figure 7 The enlarged structural diagram of the current collector is shown in FIG. Fig. 9 A schematic diagram of the structure of the second active material layer of the electrode provided in an embodiment of the present application, Fig.10 for Fig. 9 The enlarged structural diagram of the second active material layer is shown in FIG. Fig.11 A schematic diagram of processing a pole piece provided in an embodiment of the present application, Fig.12 This is one of the schematic diagrams of the structure of orderly printing on the electrode provided in the embodiment of the present application, Fig.13 This is the second structural schematic diagram of the orderly printing on the electrode provided in the embodiment of the present application.

[0056] like Figures 1 to 4 As shown, an embodiment of the present application provides a pole piece 100 , including a current collector 10 and a first active material layer 20 and a second active material layer 30 respectively located on both sides of the current collector 10 in a thickness direction.

[0057] Specifically, the electrode sheet 100 is used for manufacturing a battery cell, and the battery cell is obtained by winding a positive electrode sheet, a separator, and a negative electrode sheet stacked on each other.

[0058] Exemplarily, the electrode 100 may be a positive electrode or a negative electrode, which is not limited here. When the electrode 100 is a positive electrode, aluminum foil may be used as a current collector, and when the electrode 100 is a negative electrode, copper foil may be used as a current collector.

[0059] The first active material layer 20 is provided with a first recessed portion 21 and a first protruding portion 22. The current collector 10 is provided with a second recessed portion 11 and a second protruding portion 12. The second active material layer 30 is provided with a third recessed portion 31.

[0060] Specifically, a first recessed portion 21 is formed on a surface of the first active material layer 20 away from the current collector 10. A first protruding portion 22 is formed on a surface of the first active material layer 20 close to the current collector 10. The first protruding portion 22 and the first recessed portion 21 are arranged opposite to each other. A second recessed portion 11 is formed on a surface of the current collector 10 close to the first active material layer 20. The second recessed portion 11 and the first protruding portion 22 are arranged opposite to each other. A second protruding portion 12 is formed on a surface of the current collector 10 close to the second active material layer 30. The second protruding portion 12 and the second recessed portion 11 are arranged opposite to each other. A third recessed portion 31 is formed on a surface of the second active material layer 30 close to the current collector 10. The third recessed portion 31 and the second protruding portion 12 are arranged opposite to each other.

[0061] In a possible implementation, the first recessed portion 21, the first protruding portion 22, the second recessed portion 11, the second protruding portion 12 and the third recessed portion 31 are obtained by embossing on the pole piece 100, so that the first protruding portion 22 and the second recessed portion 11 are interlocked with each other, and the second protruding portion 12 and the third recessed portion 31 are interlocked with each other.

[0062] In some embodiments, Figure 2 and Figure 4 As shown, the pole piece 100 includes a double-sided area 40, a single-sided area 50 and an empty foil area 60. The double-sided area 40 is an area where the first active material layer 20 and the second active material layer 30 exist on both sides of the current collector 10. The single-sided area 50 is an area where the first active material layer 20 or the second active material layer 30 exists on only one side of the current collector 10. The empty foil area 60 is an area where only the current collector 10 exists. Among them, in the length direction of the pole piece 100, the length of the current collector 10 is the longest, and the lengths of the first active material layer 20 and the second active material layer 30 are different, so that the double-sided area 40, the single-sided area 50 and the empty foil area 60 are formed on the pole piece 100.

[0063] Specifically, at the head of the pole piece 100 , the current collector 10 , the first active material layer 20 and the second active material layer 30 are aligned, thereby forming a structure in which the double-sided area 40 , the single-sided area 50 and the empty foil area 60 are connected in sequence, and the pole piece 100 ends with the empty foil area 60 .

[0064] The double-sided area 40 is formed with a first recessed portion 21 and a corresponding first protruding portion 22 , a second recessed portion 11 , a second protruding portion 12 and a third recessed portion 31 .

[0065] In some embodiments, in the single-sided area 50 and the empty foil area 60, a second recessed portion 11 is also formed on the side of the current collector 10 close to the first active material layer 20. A second protruding portion 12 is also formed on the side of the current collector 10 close to the second active material layer 30, opposite to the second recessed portion 11. A third recessed portion 31 is also formed on the side of the second active material layer 30 close to the current collector 10, opposite to the second protruding portion 12.

[0066] The second recessed portion 11 formed in the single-sided area 50 and the empty foil area 60 can also store electrolyte, and the electrolyte can flow to the head and tail parts in the battery cell, and then replenish into the interior of the electrode 100 to increase the wetting of the first active material layer 20 and the second active material layer 30 .

[0067] The first recessed portion 21 and the second recessed portion 11 formed on the double-sided area 40, the single-sided area 50 and the empty foil area 60 can enhance the liquid storage capacity of the electrode 100, increase the amount of electrolyte absorbed and stored per unit area of ​​the electrode 100, enhance the lithium ion power performance, and reduce the lithium plating problem of the battery electrode.

[0068] The second protrusions 12 and the second depressions 11 formed on the current collector 10 can effectively disperse the stress on the current collector 10, the first active material layer 20 or the second active material layer 30 during the charge and discharge process, avoid stress concentration, and reduce damage caused by volume changes during the charge and discharge process.

[0069] like Figure 5 and Figure 6 As shown, on the first active material layer 20 , first flat portions 23 are formed between the first recessed portions 21 .

[0070] The thickness of the first active material layer 20 is H1, and H1 satisfies: 10 um≤H1≤100 um.

[0071] The aperture of the first recessed portion 21 is D1, and D1 satisfies: 1 mm ≤ D1 ≤ 5 mm.

[0072] In some embodiments, due to the difference in thickness of the double-sided area 40, the single-sided area 50 and the empty foil area 60, there will be a difference in the aperture D1 of the first recessed portion 21 in the double-sided area 40 and the single-sided area 50 during embossing. The difference in aperture D1 in each area is controlled within the range of 0.8 to 1.2 times.

[0073] The hole depth of the first recessed portion 21 is L1, and L1 satisfies: 10 um≤L1≤180 um.

[0074] In some embodiments, due to the difference in thickness of the double-sided area 40, the single-sided area 50 and the empty foil area 60, there will be a difference in the hole depth L1 of the first recessed portion 21 in the double-sided area 40 and the single-sided area 50 during embossing. The difference in the hole depth L1 in each area is controlled within the range of 0.8 to 1.2 times.

[0075] The hole spacing between the first recessed portions 21 is divided into a transverse spacing and a longitudinal spacing, and the transverse spacing and the longitudinal spacing may be equal or unequal.

[0076] The hole spacing between the first recessed portions 21 is W1, and W1 satisfies: W1 ≥ 1.2 times D1.

[0077] Optimizing the hole spacing design between the first recesses 21 can improve the thermal management capability of the battery, because a larger hole spacing can promote more effective heat transfer and dispersion, reduce heat accumulation in the battery under high-power operation or abnormal conditions, thereby improving the safety and stability of the battery. In addition, a larger hole spacing can also reduce the stress caused by the volume change of the electrode material during the charge and discharge process, reduce the fatigue and damage of the battery material, and extend the life of the battery.

[0078] like Figure 7 and Figure 8 As shown, on the current collector 10 , second flat portions 13 are formed between the second recessed portions 11 .

[0079] The thickness of the current collector 10 is H2, and H2 satisfies: 5um≤H2≤100um.

[0080] In some embodiments, H1 and H2 satisfy: H2≤H1.

[0081] The aperture of the second recessed portion 11 is D2, and D2 satisfies: 1 mm ≤ D2 ≤ 5 mm, and D2 ≤ D1.

[0082] In some embodiments, due to the difference in thickness of the double-sided area 40, the single-sided area 50 and the empty foil area 60, the aperture D2 of the second recessed portion 11 in each area will be different during embossing, and the difference in aperture D2 in each area is controlled within the range of 0.8 to 1.2 times.

[0083] The first recessed portion 21 of the first active material layer 20 has a larger pore size, allowing the electrolyte to penetrate into the first active material layer 20 more easily, thereby increasing the contact area between the active layer and the electrolyte; at the same time, the pore size of the first recessed portion 21 of the first active material layer 20 is larger than the pore size of the second recessed portion 11 of the current collector 10, which can reduce the diffusion resistance of lithium ions inside the first active material layer 20, thereby improving the charge and discharge efficiency of the battery, and helping to accelerate the diffusion rate of lithium ions between electrodes.

[0084] The second recessed portion 11 has a hole depth of L2, where L2 satisfies 10 um≤L2≤180 um, and L2≤L1.

[0085] In some embodiments, due to the difference in thickness of the double-sided area 40, the single-sided area 50 and the empty foil area 60, the hole depth L2 of the second recessed portion 11 in each area will be different during embossing, and the difference in the hole depth L2 in each area is controlled within the range of 0.8 to 1.2 times.

[0086] The first recessed portion 21 is made deeper, which can effectively remove the portion with higher compaction density in the first active material layer 20, thereby improving the infiltration efficiency of the electrolyte; while there is no active material on the current collector 10, and the depth of the second recessed portion 11 on the current collector 10 is smaller, which can ensure the anti-expansion stress effect of the current collector 10 and prevent the current collector 10 from having a broken belt problem.

[0087] The hole spacing between the second recessed portions 11 is divided into a transverse spacing and a longitudinal spacing, and the transverse spacing and the longitudinal spacing may be equal or unequal.

[0088] The hole spacing of the second recessed portion 11 is W2, and W2 satisfies: W2 ≥ 1.2 times D2.

[0089] Optimizing the hole spacing design between the second recesses 11 can improve the thermal management capability of the battery, because a larger hole spacing can promote more effective heat transfer and dispersion, reduce heat accumulation in the battery during high-power operation or abnormal conditions, thereby improving the safety and stability of the battery. In addition, a larger hole spacing can also reduce the stress caused by the volume change of the electrode material during the charge and discharge process, reduce the fatigue and damage of the battery material, and extend the life of the battery.

[0090] like Fig. 9 and Fig.10 As shown, on the second active material layer 30 , third flat portions 32 are formed between the third recessed portions 31 .

[0091] The thickness of the second active material layer 30 is H3, and H3 satisfies: 10 um≤H3≤100 um.

[0092] In some embodiments, H2 and H3 satisfy: H2≤H3.

[0093] The aperture of the third recessed portion 31 is D3, and D3 satisfies: 1 mm≤D3≤5 mm, and D3≤D2.

[0094] In some embodiments, due to the difference in thickness between the double-sided area 40, the single-sided area 50 and the empty foil area 60, there will be a difference in the aperture D3 of the third recessed portion 31 in the double-sided area 40 and the single-sided area 50 during embossing. The difference in aperture D3 in each area is controlled within the range of 0.8 to 1.2 times.

[0095] The hole depth of the third recessed portion 31 is L3, and L3 satisfies: 10 um≤L3≤180 um, and L3≤L2.

[0096] In some embodiments, due to the difference in thickness between the double-sided area 40, the single-sided area 50 and the empty foil area 60, there will be a difference in the hole depth L3 of the third recessed portion 31 in the double-sided area 40 and the single-sided area 50 during embossing. The difference in the hole depth L3 in each area is controlled within the range of 0.8 to 1.2 times.

[0097] The hole spacing between the third recessed portions 31 is divided into a transverse spacing and a longitudinal spacing, and the transverse spacing and the longitudinal spacing may be equal or unequal.

[0098] The hole spacing of the third recessed portion 31 is W3, and W3 satisfies: W3 ≥ 1.2 times D3.

[0099] Optimizing the hole spacing design between the third recesses 31 can improve the thermal management capability of the battery, because a larger hole spacing can promote more effective heat transfer and dispersion, reduce heat accumulation in the battery under high-power operation or abnormal conditions, thereby improving the safety and stability of the battery. In addition, a larger hole spacing can also reduce the stress caused by the volume change of the electrode material during the charge and discharge process, reduce the fatigue and damage of the battery material, and extend the life of the battery.

[0100] like Fig.11 As shown, in a possible implementation, the pole piece 100 is manufactured by embossing. By embossing, a concave structure can be formed on at least one side of the pole piece 100, and the manufacturing process is convenient.

[0101] Specifically, an embossing roller 200 and a fixed roller 300 with embossing are provided, and the pole piece 100 is placed between the embossing roller 200 and the fixed roller 300, and pressure is applied to the embossing roller 200. The embossing roller 200 rotates to move the pole piece 100 from one side of the embossing roller 200 to the other side of the embossing roller 200, thereby rolling out a concave structure on the pole piece 100. The first concave portion 21, the first convex portion 22, the second concave portion 11, the second convex portion 12, and the third concave portion 31 are embossed patterns obtained after the embossing process is performed on the pole piece 100.

[0102] Among them, a concave structure is formed on the side facing the embossing roller 200: a first concave portion 21, a second concave portion 11 and a third concave portion 31, and a convex structure is formed on the side facing the fixed roller 300: a first convex portion 22 and a second convex portion 12, and the structure of the side where the second active material layer 30 contacts the fixed roller 300 remains unchanged.

[0103] In one possible implementation, the embossing pattern is circular, thereby forming a circular recessed structure on the surface of the electrode 100. In other implementations, the embossing pattern may also be square, diamond, elliptical, teardrop-shaped, etc., as long as it is possible to form a first recessed portion 21 and a first protruding portion 22 on the first active material layer 20, a second recessed portion 11 and a second protruding portion 12 on the current collector 10, and a third recessed portion 31 on the second active material layer 30.

[0104] Preferably, the embossing pattern should be such that the pole piece does not have any sharp corners or sharp edges, and the pressure on the embossing roller 200 is appropriate to prevent the embossing roller 200 from piercing the pole piece 100 or causing the pole piece 100 to lose powder during embossing, thereby affecting safety and capacity.

[0105] By setting the shape and spacing of the embossing, the area of ​​the groove wall in the recessed structure can be increased, further facilitating the electrolyte to infiltrate the interior of the active material layer, thereby achieving the effect of improving the ion transmission capacity.

[0106] In some embodiments, the embossing pattern of the embossing process may be an ordered array distribution or a disordered distribution.

[0107] Preferably, the embossing process adopts an orderly array distribution, and the first recessed portion 21, the first protruding portion 22, the second recessed portion 11, the second protruding portion 12 and the third recessed portion 31 are orderly arrayed on the electrode 100. The recessed structure on the prepared electrode 100 is evenly distributed, which can improve the distribution of electrolyte storage on the electrode 100 and improve the active material infiltration of each area on the electrode 100.

[0108] like Fig.12 and Fig.13 Shown are two preferred embossing patterns distributed in orderly arrays on the pole pieces provided in this application.

[0109] In one possible implementation, a concave structure is formed on the entire surface of the pole piece 100 by an embossing process, that is, the first concave portion 21, the first protruding portion 22, the second concave portion 11, the second protruding portion 12 and the third concave portion 31 are distributed on the entire surface of the pole piece 100, but it is not limited thereto. In other implementations, embossing can also be performed only on the edge or other designated areas of the pole piece 100, that is, a concave structure is formed on the edge or other designated areas of the pole piece 100, that is, the first concave portion 21, the first protruding portion 22, the second concave portion 11, the second protruding portion 12 and the third concave portion 31 are distributed on the edge or other designated areas of the pole piece 100, as long as the embossing process can be used to improve the liquid storage function of the pole piece 100 and prevent the lithium precipitation problem in the corresponding area.

[0110] The pole piece 100 provided in the embodiment of the present application includes a current collector 10 and a first active material layer 20 and a second active material layer 30 respectively located on both sides of the current collector 10 in the thickness direction. A first recessed portion 21 is formed on a side of the first active material layer 20 away from the current collector 10, and a first protruding portion 22 is formed on a side of the first active material layer 20 close to the current collector 10 relative to the first recessed portion 21; a second recessed portion 11 is formed on a side of the current collector 10 close to the first active material layer 20 relative to the first protruding portion 22, and a second protruding portion 12 is formed on a side of the current collector 10 close to the second active material layer 30 relative to the second recessed portion 11.

[0111] The first recessed portion 21 can store more electrolyte, and the contact area between the electrolyte and the first active material layer 20 can also be increased through the first recessed portion 21. The electrolyte can infiltrate into the interior of the first active material layer 20 through the first recessed portion 21, and the first protrusion 22, the second recessed portion 11, the second protrusion 12 and the third recessed portion 31 formed between the current collector 10 and the first active material layer 20 can increase the infiltration channel of the electrolyte, which is convenient for complete infiltration of the electrolyte, so as to achieve the effect of improving the ion transmission capacity, thereby reducing the problem of lithium precipitation of the electrode during the charging and discharging process of the battery. The second protrusion 12 and the second recessed portion 11 formed by the current collector 10 can effectively disperse the stress on the current collector 10 or the active material layer during the charging and discharging process, avoid stress concentration, reduce the damage caused by volume change during the charging and discharging process, improve the battery cycle performance, and at the same time increase the service life of the battery.

[0112] In addition, the embodiment of the present application further provides a battery, including a battery housing and a battery cell, wherein the battery cell is made by a pole piece 100, and the battery cell is located in the battery housing.

[0113] The battery is not limited to lithium batteries, and in the future this technology may be applied to sodium batteries, etc. In the present application, lithium-ion batteries are preferred.

[0114] The specific structure, working principle and function of the electrode 100 have been described in detail in the above embodiments and will not be repeated here. It should be noted that the preparation process of the lithium-ion battery is as follows:

[0115] Step 1: Preparation of positive electrode sheet: prepare positive electrode active layer slurry, apply positive electrode active material slurry on the surface of current collector 10, and obtain electrode sheet 100 after baking and rolling by embossing roller 200. A certain position of electrode sheet 100 has a first electrode ear groove of fixed size. The positive electrode ear is welded in the first electrode ear groove by laser or ultrasonic welding. First electrode ear tape is pasted on both sides of the electrode sheet at the groove position, and second electrode ear tape is pasted on the image negative electrode sheet. The image of the first electrode ear tape completely covers the second electrode ear tape.

[0116] Step 2: Preparation of negative electrode sheet: prepare negative electrode active layer slurry, apply it on carbon-coated copper foil, and obtain negative electrode sheet after baking and rolling. A certain position of the negative electrode sheet has a second pole ear groove with a fixed size. The negative pole ear is welded in the second pole ear groove by laser or ultrasonic welding, and the second pole ear adhesive tape is pasted on both sides of the slotted pole sheet, and the first pole ear adhesive tape is pasted on the image positive electrode sheet, and the image of the first pole ear adhesive tape completely covers the second pole ear adhesive tape;

[0117] Step 3: The positive and negative electrode sheets are cut, sliced ​​and wound with the separator to obtain a winding core;

[0118] Step 4: After packaging, baking, liquid injection, formation, secondary sealing, sorting and OCV (open circuit voltage) testing, a lithium-ion battery is obtained.

[0119] The electrolyte is a commercially available conventional electrolyte, and the lithium salt therein is LiFP6.

[0120] In the battery provided in the embodiment of the present application, the first recessed portion 21 can store more electrolyte, and the contact area between the electrolyte and the first active material layer 20 can also be increased through the first recessed portion 21. The electrolyte can infiltrate the interior of the first active material layer 20 through the first recessed portion 21, and the first protrusion 22, the second recessed portion 11, the second protrusion 12 and the third recessed portion 31 formed between the current collector 10 and the first active material layer 20 can increase the infiltration channel of the electrolyte, which is convenient for complete infiltration of the electrolyte, so as to achieve the effect of improving the ion transmission capacity, thereby reducing the problem of lithium precipitation of the electrode during the charging and discharging process of the battery. The second protrusion 12 and the second recessed portion 11 formed by the current collector 10 can effectively disperse the stress on the current collector 10 or the active material layer during the charging and discharging process, avoid stress concentration, reduce the damage caused by volume change during the charging and discharging process, improve the battery cycle performance, and at the same time increase the service life of the battery.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A pole piece, characterized in that: It includes a current collector, a first active material layer and a second active material layer, wherein the first active material layer and the second active material layer are respectively located on two opposite sides of the current collector in a thickness direction; A first concave portion is formed on a side of the first active material layer away from the current collector, and a first convex portion is formed on a side of the first active material layer close to the current collector, wherein the first convex portion and the first concave portion are arranged opposite to each other; A second recessed portion is formed on one side of the current collector close to the first active material layer, and the second recessed portion and the first protruding portion are arranged oppositely. A second protruding portion is formed on one side of the current collector close to the second active material layer, and the second protruding portion and the second recessed portion are arranged oppositely.

2. The pole piece according to claim 1, characterized in that: A third recessed portion is formed on a surface of the second active material layer close to the current collector, and the third recessed portion and the second protruding portion are arranged opposite to each other.

3. The pole piece according to claim 2, characterized in that: The first protruding portion and the second recessed portion are interlocked with each other, and / or the second protruding portion and the third recessed portion are interlocked with each other.

4. The pole piece according to claim 2, characterized in that: The aperture of the first recessed portion is D1, the aperture of the second recessed portion is D2, and the aperture of the third recessed portion is D3, and D1, D2 and D3 satisfy: D3≤D2≤D1; And / or, D1 satisfies: 1mm≤D1≤5mm; And / or, D2 satisfies: 1mm≤D2≤5mm; And / or, D3 satisfies: 1mm≤D3≤5mm.

5. The pole piece according to claim 4, characterized in that: The hole spacing between the first recessed parts is W1, the hole spacing between the second recessed parts is W2, and the hole spacing between the third recessed parts is W3, and W1 satisfies: W1 ≥ 1.2 times D1; and / or, W2 satisfies: W2 ≥ 1.2 times D2; And / or, W3 satisfies: W3 ≥ 1.2 times D3.

6. The pole piece according to claim 2, characterized in that: The hole depth of the first recessed portion is L1, the hole depth of the second recessed portion is L2, and the hole depth of the third recessed portion is L3, and L1, L2 and L3 satisfy: L3≤L2≤L1; And / or, L1 satisfies: 10um≤L1≤180um; And / or, L2 satisfies: 10um≤L2≤180um; And / or, L3 satisfies: 10um≤L3≤180um.

7. The pole piece according to any one of claims 2 to 6, characterized in that: The pole piece includes a double-sided area, a single-sided area and an empty foil area, the double-sided area is an area where the first active material layer and the second active material layer exist on both sides of the current collector, the single-sided area is an area where the first active material layer or the second active material layer exists on only one side of the current collector, the empty foil area is an area where only the current collector exists, and the first recessed portion and the second recessed portion are formed in the double-sided area; and / or The hollow foil area is formed with the second concave portion and the second convex portion.

8. The pole piece according to claim 7, characterized in that: The third recessed portion is formed in the double-sided region; and / or the second active material layer in the single-sided region.

9. The pole piece according to any one of claims 2 to 6, characterized in that: The first recessed portion, the first protruding portion, the second recessed portion, the second protruding portion and the third recessed portion are respectively distributed in an orderly array on the pole piece; and / or The first recessed portion, the first protruding portion, the second recessed portion, the second protruding portion and the third recessed portion are respectively distributed on the entire surface or edge of the pole piece.

10. A battery, characterized in that: It comprises a battery casing and a battery cell, wherein the battery cell comprises a pole piece as claimed in any one of claims 1 to 9, and the battery cell is located in the battery casing.

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