Pole piece and battery

Abstract

The utility model provides a pole piece and a battery, the pole piece comprises a current collector and an active material layer coated on the surface of the current collector, a double-sided paste coating area is formed by partial section of the pole piece, and the active material layers are coated on the two side surfaces of the current collector in the double-sided paste coating area; the double-sided pasting area in the first direction comprises a first end area, a middle area and a second end area which are arranged in sequence, the active material layer in the first end area is provided with a plurality of first pits, the active material layer in the second end area is provided with a plurality of second pits, and the active material layer in the middle area is provided with a plurality of third pits; wherein the average depth of each first pit is smaller than the average depth of each third pit, and / or the average depth of each second pit is smaller than the average depth of each third pit. By improving the total amount of the electrolyte, the wettability of active substances and the structural strength of the end part of the pole piece, the energy density and the battery performance of the battery are improved.

Description

Technical Field

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

[0002] With the popularization of electric vehicles, portable devices and renewable energy applications, batteries are being used more and more widely in all walks of life, which has also led to higher and higher performance requirements for batteries in terms of energy density, charge and discharge cycle life, stability and safety. Utility Model Content

[0003] In view of this, the embodiments of the present application are dedicated to providing a pole piece, which, by optimizing the pole piece structure, enables the battery made using the pole piece to increase the energy density, enhance the stability and safety, and improve the cycle life, so as to improve the performance of the battery in many aspects.

[0004] The present application provides a pole piece, comprising a current collector and an active material layer coated on the surface of the current collector, wherein a partial section of the pole piece forms a double-sided paste area, and both sides of the current collector in the double-sided paste area are coated with the active material layer; in a first direction, the double-sided paste area comprises a first end area, a middle area, and a second end area arranged in sequence, the active material layer in the first end area is provided with a plurality of first pits, the active material layer in the second end area is provided with a plurality of second pits, and the active material layer in the middle area is provided with a plurality of third pits; wherein,

[0005] The average depth of each of the first pits is smaller than the average depth of each of the third pits, and / or the average depth of each of the second pits is smaller than the average depth of each of the third pits.

[0006] In one possible embodiment, in the direction from the middle zone to the first end zone, the depth of the first pit gradually decreases as gradually moving away from the middle zone, and / or, in the direction from the middle zone to the second end zone, the depth of the second pit gradually decreases as gradually moving away from the middle zone.

[0007] In a possible implementation manner, the depth of the first pit is D1, the depth of the second pit is D2, and the depth of the third pit is D3, wherein 1 μm≤D3-D1≤20 μm, and / or 1 μm≤D3-D2≤20 μm;

[0008] and / or, a dimension of the first end region in the first direction is L1, and 10 mm ≤ L1 ≤ 45 mm or 5 mm ≤ L1 ≤ 40 mm;

[0009] And / or, a dimension of the second end region in the first direction is L2, and 3mm≤L2≤10mm.

[0010] In a possible implementation, in the second direction, the active material layer has a main body region and an edge region arranged in sequence, the thickness of the active material layer in the edge region is less than the thickness of the active material layer in the main body region, the edge region is located on a side of the main body region close to the pole ear, and a plurality of pits are provided in both the main body region and the edge region.

[0011] The depth of the pit in the edge region gradually decreases in a direction approaching the pole ear.

[0012] In one possible implementation, the depth of the pits in the edge area is dthin, the depth of the pits in the main area is dmain, 1μm≤dmain-dthin≤30μm; and / or, the size of the edge area in the second direction is W, and 1mm≤W≤10mm.

[0013] In a possible implementation manner, in the thickness direction, positions on the current collector corresponding to each of the first pits, each of the second pits, and each of the third pits all have recessed portions.

[0014] In a possible implementation manner, a plurality of the recessed portions are formed on both side surfaces of the current collector, and the recessed portions on both side surfaces of the current collector are arranged alternately.

[0015] In a possible implementation manner, the diameter of the recessed portion is R, the diameter of the pit corresponding to the recessed portion is r, and 20%≤r / R≤80%;

[0016] And / or, the depth of the recessed portion is D, the depth of the pit corresponding to the recessed portion is d, and 1%≤d / D≤80%.

[0017] In a possible implementation manner, the thickness of the active material layer in the first end region is less than the thickness of the active material layer in the middle region, and the thickness of the active material layer in the first end region gradually decreases in a direction gradually away from the middle region;

[0018] And / or, the thickness of the active material layer in the second end region is less than the thickness of the active material layer in the middle region, and the thickness of the active material layer in the second end region gradually decreases in a direction gradually away from the middle region.

[0019] An embodiment of the present application further provides a battery, comprising a battery cell, wherein the battery cell comprises a first pole piece, a second pole piece and a diaphragm, and the first pole piece and / or the second pole piece is the pole piece described in any one of the above items.

[0020] In a possible implementation, the battery cell is a wound battery cell;

[0021] And / or, the diaphragm includes a base film and an adhesive layer, the base film is bonded to the surface of the first pole piece and / or the second pole piece through the adhesive layer, and a part of the adhesive layer is embedded in a pit on the active material layer, and the embedding depth is H, and H satisfies: 0<H<2.5μm;

[0022] And / or, the surface of a partial area of ​​the active material layer of the first pole piece and / or the second pole piece has a colloid, the area of ​​the active material layer having the colloid is S1, the total area of ​​the active material layer is S, and 12.5%<S1 / Stotal<95%.

[0023] The pole piece provided in the present application has a plurality of pits arranged on the active material layer in the double-sided paste-coated area of ​​the pole piece, and the average depth of the pits in one or two end areas of the double-sided paste-coated area in the first direction is lower than the average depth of the pits in the middle area. Compared with the prior art, the use of the pole piece to make a battery has the following beneficial effects: first, it can not only increase the specific surface area of ​​the active material layer and improve the contact area between the electrolyte and the active material of the battery, but also increase the rate at which the electrolyte penetrates the active material layer, thereby improving the charge transfer speed and the charge and discharge performance of the battery; second, it can increase the capacity of the electrolyte, which not only improves the energy density of the battery, so that the battery can store more electrical energy at the same volume, but also enables the manufactured battery to have sufficient electrolyte for replenishment during the cycle, thereby ensuring the electrolyte wettability of the battery cell, avoiding insufficient wettability, and improving the phenomenon of lithium plating on the pole piece, thereby improving the safety performance of the battery, extending the cycle life of the battery, and ensuring the discharge capacity of the battery; third, the average depth of the pits in one or two end areas of the double-sided paste area is lower than the average depth of the pits in the middle area, which is consistent with the pit depth of the entire double-sided paste area, which can improve the structural strength of the pole piece end, prevent the end area from curling or wrinkling, and thus improve the smoothness of charge transfer in the end area, and prevent the phenomenon of lithium plating black spots that are easy to appear at the end. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Shown is a first schematic diagram of a pole piece in some embodiments of the present application;

[0025] Figure 2 The figure shows a first cross-sectional schematic diagram of a pole piece in an embodiment of the present application;

[0026] Figure 3 Shown is a second schematic diagram of a pole piece in some embodiments of the present application;

[0027] Figure 4Shown is a third schematic diagram of a pole piece in some embodiments of the present application;

[0028] Figure 5 Shown is a fourth schematic diagram of a pole piece in some embodiments of the present application;

[0029] Figure 6 Shown is a second cross-sectional schematic diagram of a pole piece in some embodiments of the present application;

[0030] Figure 7 Shown is a third cross-sectional schematic diagram of a pole piece in some embodiments of the present application;

[0031] Figure 8 Shown are cross-sectional schematic diagrams of current collectors and active material layers in some embodiments of the present application;

[0032] Fig. 9 Shown is a schematic cross-sectional view of a diaphragm and a pole piece in some embodiments of the present application.

[0033] Figure 1-9 middle:

[0034] 1. Current collector; 11. Recessed portion; 2. Active material layer; 21. Edge region; 3. Diaphragm; 31. Base film; 32. Adhesive layer; 4. Double-sided paste coating region; 41. First end region; 42. Second end region; 43. Middle region. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] Please refer to the attached Figure 1-9 , the embodiment of the present application provides a pole piece, which can be a positive pole piece or a negative pole piece, which is not specifically limited here. The pole piece includes a current collector 1 and an active material layer 2 coated on the surface of the current collector 1. In a first direction (such as Figure 1 In the direction shown in the figure, both sides of the surface of the partial section of the current collector 1 are coated with the active material layer 2, and the partial section of the current collector 1 with the active material layer 2 on both sides of the surface forms the double-sided paste area 4 of the electrode. If only one side of the surface of the partial section of the current collector 1 is coated with the active material layer 2, it can be called a single-sided paste area (such as the attached Figure 2 The first direction may be the length direction of the current collector 1 or the pole piece. For example, when the pole piece is used to make a wound battery cell, the first direction is usually the length direction of the pole piece. The second direction (eg Figure 1 The direction shown in ( ) is usually the width direction of the pole piece.

[0037] Among them, in the double-sided pasting area 4, there are multiple pits on the active material layer 2 on one side surface of the current collector 1, or there are multiple pits on the active material layer 2 on both sides of the current collector 1. It can also be said that there are multiple pits on the active material layer 2 in the double-sided pasting area 4, and the multiple pits are located on one side surface of the current collector 1 or distributed on both sides of the current collector 1. Specifically, the double-sided pasting area 4 is divided into a first end area 41, a middle area 43 and a second end area 42 in sequence along the first direction, or it can be said that the first end area 41, the middle area 43 and the second end area 42 are arranged in sequence along the first direction. The pits on the active material layer 2 in the first end area 41 are recorded as first pits; the pits on the active material layer 2 in the second end area 42 are recorded as second pits; the pits on the active material layer 2 in the middle area 43 are recorded as third pits.

[0038] At the same time, in the present application, the average depth of each first pit in the first end area 41 is less than the average depth of each third pit in the middle area 43, and / or the average depth of each second pit in the second end area 42 is less than the average depth of each third pit in the middle area 43. Then, the pole piece provided by the present application is not only provided with a plurality of pits on the active material layer 2 of the double-sided paste area 4 of the pole piece, but also the average depth of the pits in one or two end areas of the double-sided paste area 4 in the second direction is lower than the average depth of the pits in the middle area 43. On the basis of also providing pits in the end area, reducing the depth of the pits in this section, compared with the same depth of the pits in the entire double-sided paste area, can improve the structural strength of the end section of the pole piece, and on the basis of providing pits to improve the current collection performance such as charge transfer, the structural strength of the pole piece end is improved as much as possible to prevent the end area from wrinkling or bending, and prevent the occurrence of undesirable phenomena such as lithium deposition due to wrinkling or bending of the end area.

[0039] Then, using the electrode provided by the present application to manufacture a battery has the following beneficial effects compared to the prior art: first, a plurality of pits are arranged on the surface of the electrode, which can not only increase the specific surface area of ​​the active material layer 2 and improve the contact area between the electrolyte and the active material of the battery, but also increase the rate at which the electrolyte penetrates the active material layer 2, thereby improving the charge transfer speed and the charge and discharge performance of the battery; second, the capacity of the electrolyte can be increased, which not only improves the energy density of the battery, so that the battery can store more electrical energy at the same volume, but also ensures that the manufactured battery has sufficient electrolyte to be replenished during the recycling process, thereby ensuring the electrolyte wettability of the battery cell and avoiding infiltration. The invention can improve the lithium deposition phenomenon of the electrode, enhance the safety performance of the battery, prolong the cycle life of the battery, and ensure the discharge capacity of the battery; on the third aspect, the average depth of the pits in one or two end areas of the double-sided pasted area 4 is lower than the average depth of the pits in the middle area 43, which is consistent with the depth of the pits in the entire double-sided pasted area. The structural strength of the end section of the electrode can be improved. On the basis of setting the pits to improve the current collection performance such as charge transfer, the structural strength of the end of the electrode can be improved as much as possible to prevent the end section from wrinkling or bending, which may easily lead to adverse problems such as lithium deposition, thereby improving the smoothness of charge transfer in the end area and preventing the black spots of lithium deposition that are easy to appear at the end.

[0040] In some embodiments, in the direction from the middle region 43 to the first end region 41, that is, in the first direction and in a direction gradually away from the middle region 43, the depth of the first pits arranged along this direction gradually decreases as the distance from the middle region 43 gradually increases; that is, the farther away from the middle region 43 and closer to the edge of the pole piece in the first direction, the smaller the depth of the first pit. Figure 2 As shown, the depths of the first pits arranged along the direction from the first end area 41 to the middle area 43 are recorded as d1, d2, d3, d4..., then, d1<d2<d3<... In this way, the depths of the first pits in the first end area 41 are gradually changing instead of being in a disorderly state of varying depths, which is conducive to manufacturing, and the closer to the edge of the pole piece, the shallower the pit, the stronger the structural strength of the pole piece, thereby improving the phenomenon that the end of the pole piece is easily wrinkled or bent.

[0041] In some embodiments, in the direction from the middle region 43 to the second end region 42, that is, along the first direction and along the direction gradually away from the middle region 43, the depth of the second pits arranged along this direction gradually decreases as they gradually move away from the middle region 43. That is, the farther away from the middle region 43 and closer to the edge of the pole piece in the first direction, the smaller the depth of the second pit. Figure 2As shown, the depths of the second pits arranged along the direction from the second end area 42 to the middle area 43 are recorded as dn, d(n-1), d(n-2), d(n-3)..., then, dn<d(n-1)<d(n-2)<... In this way, the depths of the second pits in the second end area 42 are gradually changing instead of being in a disorderly state of varying depths, which is conducive to manufacturing, and the closer to the edge of the pole piece, the shallower the pit, the stronger the structural strength of the pole piece, which improves the wrinkling or bending phenomenon of the end of the pole piece, thereby improving the relative stability between the end of the pole piece and the diaphragm 3, and also improving the lithium deposition black spot phenomenon.

[0042] From the above, it can be seen that in the double-sided paste area 4, the depth of the pit in the middle area 43 is greater than the depth of the pit in the two end areas. While effectively increasing the liquid retention amount and helping to improve the cycle life of the battery, the greater depth of the middle pit can effectively improve the heat dissipation effect of the middle area, prevent heat accumulation in the middle area, and facilitate battery heat dissipation.

[0043] The size of the first end region 41 and the second end region 42 in the first direction is smaller than the size of the middle region 43 in the first direction, and refers to the partial section of the double-sided paste region 4 close to the edge of the pole piece in the first direction. In some embodiments, the first end region 41 and the second end region 42 may be thinning sections corresponding to the thinning of the thickness of the active material layer 2 in the first direction. For example, the thickness of the active material layer 2 in the first end region 41 is smaller than the thickness of the active material layer 2 in the middle region 43, and the thickness of the active material layer 2 in the first end region 41 gradually decreases in the direction gradually away from the middle region 43. The thickness of the active material layer 2 in the second end region 42 is smaller than the thickness of the active material layer 2 in the middle region 43, and the thickness of the active material layer 2 in the second end region 42 gradually decreases in the direction gradually away from the middle region 43.

[0044] The size of the first end region 41 in the first direction is L1. In some specific embodiments, when the pole piece is used to make a wound battery cell, or is a pole piece of a wound battery cell, 10mm≤L1≤45mm, or 5mm≤L1≤40mm; for example, 5mm, 8mm, 10mm, 12mm, 15mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 32mm, 35mm, 38mm, 40mm, 42mm, 45mm. If the size of L1 is too large, it will affect the total amount of the active material layer 2, and affect the energy density, charge and discharge performance, total charge and discharge performance of the battery. If L1 is too small, the effect of setting the pit is affected, and the beneficial effects described in the above embodiments will be weakened. Of course, in some other embodiments, the size L1 of the first end region 41 can also be a value less than 5mm or greater than 40mm.

[0045] Similarly, the size of the second end region 42 in the first direction is L2. In some specific embodiments, when the pole piece is used to make a wound battery cell, or is a pole piece of a wound battery cell, 3mm≤L2≤10mm, for example, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm. If the size of L2 is too large, it will affect the total amount of the active material layer 2, and affect the energy density, charge and discharge performance, total charge and discharge performance of the battery. If L2 is too small, the effect of setting the pit is affected, and the beneficial effects described in the above embodiments will be weakened. Of course, in some other embodiments, the size L2 of the second end region 42 can also be a value less than 3mm or greater than 10mm.

[0046] The depth of the first pit is less than the depth of the third pit. The depth of the first pit is recorded as D1, the depth of the second pit is recorded as D2, and the depth of the third pit is recorded as D3. In some preferred embodiments, 1μm≤D3-D1≤20μm, that is, the depth difference between the third pit and the first pit is between 1 micron and 20 microns, for example, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm. The difference between the pit depth in the first end area 41 and the pit depth in the middle area is greater than 1 micron, which is beneficial to improving the uniformity of current distribution in different areas of the electrode and improving the performance and cycle life of the battery; and the difference cannot exceed 20μm, which can prevent the volume of active materials in different areas of the electrode from being too different, and is also beneficial to improving the uniformity of current distribution in different areas of the electrode, and can also prevent affecting the total amount of active materials on the electrode.

[0047] Similarly, in some preferred embodiments, 1μm≤D3-D2≤20μm, that is, the depth difference between the third pit and the second pit is between 1 μm and 20 μm, for example, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm. The difference between the pit depth in the second end region 42 and the pit depth in the middle region is greater than 1 μm, which is beneficial to improve the uniformity of current distribution in different regions of the pole piece and improve the performance and cycle life of the battery; and the difference cannot exceed 20μm, which can prevent the volume of active materials in different regions of the pole piece from being too different, which is also beneficial to improve the uniformity of current distribution in different regions of the pole piece and prevent the total amount of active materials on the pole piece from being affected.

[0048] The pole piece can be a multi-ear pole piece, such as Figure 4 and Figure 5As shown, a plurality of pole tabs are arranged on one side of the second direction of the current collector 1, and the plurality of pole tabs are arranged along the first direction. The current collector 1 and the pole tabs are an integrated structure, and the multi-pole tab pole sheet can be used to manufacture a multi-pole tab wound battery cell. Alternatively, the pole sheet can be a conventional pole tab structure, such as a single-pole tab pole sheet, and a pole tab is arranged on one side of the second direction of the current collector 1, and the single-pole tab pole sheet can be used to manufacture a conventional wound battery cell.

[0049] In the second direction, the active material layer 2 has a main body region and an edge region 21. The thickness of the active material layer 2 in the edge region 21 is less than that in the main body region. In other words, the thickness of the active material layer 2 in the edge region 21 is less than that in the main body region. The edge region 21 is located on the side of the main body region close to the pole ear. Figure 5 As shown, the edge region 21 is closer to the electrode tab than the main region. The thickness of the active material layer 2 in the edge region 21 gradually decreases in the direction close to the electrode tab.

[0050] A plurality of pits are arranged in the main area and the edge area 21, and the depth of the pits in the edge area 21 gradually decreases as it approaches the tab. Figure 6 As shown, the depths of the pits arranged along the direction from the pole ear to the main area are recorded as d1, d2, d3, d4... Then, d1<d2<d3<.... As the thickness of the active material layer 2 in the edge area 21 gradually decreases, the depth of the pits is also gradually reduced in this direction, which can avoid the risk of short circuit due to the exposure of the current collector 1.

[0051] The size of the edge area 21 in the second direction is W. In some specific embodiments, 1 mm≤W≤10 mm, for example, it can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm.

[0052] like Figure 7 As shown, the depth of the pit in the main area is dmain, and the depth of the pit in the edge area 21 is dthin. The relationship between dmain and dthin satisfies: 1μm≤dmain-dthin≤30μm. Considering that the thickness of the active material layer 2 in the edge area 21 is relatively thin, the difference in the depth of the pits in the main area and the edge area 21 is greater than 1 micron but not more than 30 microns. While adding electrolyte in the edge area 21, more active materials can be retained in the edge area 21, thereby improving the energy density of the battery while ensuring the wettability of the electrolyte.

[0053] like Figure 8As shown, in the thickness direction, the positions on the current collector 1 corresponding to each first pit, each second pit and each third pit all have a recessed portion 11, and the recessed portion 11 protrudes from the other side surface of the current collector 1 and forms a bulge on the other side surface of the current collector 1. That is, a part of the current collector 1 is recessed from one side to the other side in the thickness direction and protrudes from the other side surface to form a bulge on the other side. Such a configuration expands the surface area of ​​the current collector 1, can increase the current collection area, help improve the current conductivity between the electrode and the current collector 1, reduce resistance, and thus improve the conductivity and performance of the battery; at the same time, it can also release the stress on the current collector 1 during the bending process, which helps to slow down the shedding or damage of the active material layer 2.

[0054] In a preferred embodiment, the active material layer 2 on both side surfaces of the current collector 1 in the double-sided pasted area 4 has pits, both side surfaces of the current collector 1 have recessed portions 11, and the recessed portions 11 on both side surfaces are arranged alternately, so both side surfaces of the current collector 1 have recessed portions 11 and protrusions.

[0055] The diameter of the concave portion 11 on the current collector 1 is denoted as R, and the diameter of the pit (actually the first pit, the second pit, or the third pit) on the active material layer 2 opposite to the concave portion 11 is denoted as r, and R and r satisfy 20%≤r / R≤80%. It should be noted that, if Figure 8 As shown, the diameter of the recessed portion 11 refers to the maximum size of the recessed portion 11 in the first direction, and the diameter of the pit refers to the maximum size of the pit in the first direction. The diameter ratio of the recessed portion 11 on the current collector 1 and the pit on the active material layer 2 cannot differ too much, so as to maximize the diameter of the pit on the active material layer 2, effectively increase the effective contact area between the active material layer 2 and the electrolyte, enhance the battery performance, and ensure the structural strength of the current collector 1 to prevent the current collector 1 from breaking.

[0056] The depth of the concave portion 11 on the current collector 1 is recorded as D, and the depth of the pit on the active material layer 2 corresponding to the concave portion 11 is recorded as d, and d and D satisfy 1%≤d / D≤80%. The depth ratio of the concave portion 11 on the current collector 1 and the pit on the active material layer 2 cannot differ too much, so as to maximize the depth of the pit on the active material layer 2, effectively increase the effective contact area between the active material layer 2 and the electrolyte, enhance the battery performance, and ensure the structural strength of the current collector 1 to prevent the current collector 1 from breaking.

[0057] An embodiment of the present application also provides a battery, which includes a battery cell, and the battery cell includes a first pole piece, a second pole piece and a diaphragm 3. The first pole piece and / or the second pole piece are the pole pieces described in the above embodiments. The battery has the beneficial effects of the pole pieces in the above embodiments.

[0058] The cell may be a wound cell.

[0059] In some embodiments, the diaphragm 3 includes a base film 31 and an adhesive layer 32. The base film 31 is bonded to the surface of the first electrode sheet and / or the second electrode sheet through the adhesive layer 32, that is, the base film 31 has an adhesive layer 32 on one side or both sides in the thickness direction, and the base film 31 is bonded to one or both of the positive and negative electrode sheets through the adhesive layer 32. When the base film 31 is bonded to the electrode sheet having a pit on the active material layer 2, since the adhesive layer 32 is bonded to the active material layer 2, in some embodiments, such as Fig. 9 As shown, the adhesive layer 32 is partially embedded in the pit on the active material layer 2, and the embedding depth is H, and H satisfies: 0<H<2.5μm. Such a setting can ensure that the base film 31 is firmly bonded to the surface of the pole piece, effectively preventing the base film 31 and the pole piece from being relatively displaced to cause safety problems such as short circuit. At the same time, the embedding depth of the adhesive layer 32 is limited to no more than 2.5 microns to prevent the adhesive layer 32 from being too thick to affect the energy density of the battery and the charge and discharge capacity of the battery.

[0060] The surface of a part of the active material layer 2 of the first pole piece and / or the second pole piece has a colloid, which can be a separate colloid or formed by a part of the colloid of the adhesive layer 32 of the diaphragm 3. The area of ​​the active material layer 2 having the colloid is S1, the total area of ​​the active material layer 2 is S, and 12.5%<S1 / Stotal<95%. The colloid is present on the pole piece surface and the area ratio of the colloid is limited, which can ensure that the base film 31 and the pole piece can be firmly bonded to prevent the base film 31 and the pole piece from having a low peeling force.

[0061] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0062] The components and devices involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the drawings. As will be appreciated by those skilled in the art, these components and devices can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, meaning "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The word "such as" used here refers to the phrase "such as but not limited to", and can be used interchangeably with it.

[0063] It should also be noted that in the device and apparatus of the present application, each component can be decomposed and / or reassembled, and such decomposition and / or reassembly should be regarded as an equivalent solution of the present application.

[0064] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0065] It should be understood that the qualifiers "first", "second" and "third" used in the description of the embodiments of the present application are only used to clearly explain the technical solutions and cannot be used to limit the scope of protection of the present application.

[0066] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

[0067] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A pole piece, characterized in that: It includes a current collector and an active material layer coated on the surface of the current collector, a partial section of the pole piece forms a double-sided paste area, and both sides of the current collector in the double-sided paste area are coated with the active material layer; in the first direction, the double-sided paste area includes a first end area, a middle area, and a second end area arranged in sequence, the active material layer in the first end area is provided with a plurality of first pits, the active material layer in the second end area is provided with a plurality of second pits, and the active material layer in the middle area is provided with a plurality of third pits; wherein, The average depth of each of the first pits is smaller than the average depth of each of the third pits, and / or the average depth of each of the second pits is smaller than the average depth of each of the third pits.

2. The pole piece according to claim 1, characterized in that: In the direction from the middle zone to the first end zone, the depth of the first pit gradually decreases as gradually moving away from the middle zone, and / or, in the direction from the middle zone to the second end zone, the depth of the second pit gradually decreases as gradually moving away from the middle zone.

3. The pole piece according to claim 1, characterized in that: The depth of the first pit is D1, the depth of the second pit is D2, and the depth of the third pit is D3, wherein 1 μm≤D3-D1≤20 μm, and / or 1 μm≤D3-D2≤20 μm; and / or, a dimension of the first end region in the first direction is L1, and 10 mm ≤ L1 ≤ 45 mm or 5 mm ≤ L1 ≤ 40 mm; And / or, a dimension of the second end region in the first direction is L2, and 3mm≤L2≤10mm.

4. The pole piece according to any one of claims 1 to 3, characterized in that: In the second direction, the active material layer has a main body region and an edge region arranged in sequence, the thickness of the active material layer in the edge region is less than the thickness of the active material layer in the main body region, the edge region is located on a side of the main body region close to the pole ear, and a plurality of pits are provided in both the main body region and the edge region. The depth of the pit in the edge region gradually decreases in a direction approaching the pole ear.

5. The pole piece according to claim 4, characterized in that: The depth of the pit in the edge region is dthin, the depth of the pit in the main region is dmain, 1μm≤dmain-dthin≤30μm; And / or, a size of the edge area in the second direction is W, and 1mm≤W≤10mm.

6. The pole piece according to claim 1, characterized in that: In the thickness direction, positions on the current collector corresponding to each of the first pits, each of the second pits, and each of the third pits have recessed portions.

7. The pole piece according to claim 6, characterized in that: A plurality of the recessed portions are formed on both side surfaces of the current collector, and the recessed portions on both side surfaces of the current collector are arranged alternately.

8. The pole piece according to claim 6, characterized in that: The diameter of the recessed portion is R, the diameter of the pit corresponding to the recessed portion is r, and 20%≤r / R≤80%; And / or, the depth of the recessed portion is D, the depth of the pit corresponding to the recessed portion is d, and 1%≤d / D≤80%.

9. The pole piece according to claim 1, characterized in that: The thickness of the active material layer in the first end region is smaller than the thickness of the active material layer in the middle region, and the thickness of the active material layer in the first end region gradually decreases in a direction gradually away from the middle region; And / or, the thickness of the active material layer in the second end region is less than the thickness of the active material layer in the middle region, and the thickness of the active material layer in the second end region gradually decreases in a direction gradually away from the middle region.

10. A battery, characterized in that: The invention comprises a battery cell, wherein the battery cell comprises a first pole piece, a second pole piece and a diaphragm, and the first pole piece and / or the second pole piece are the pole pieces according to any one of claims 1 to 9.

11. The battery according to claim 10, characterized in that The battery cell is a wound battery cell; And / or, the diaphragm includes a base film and an adhesive layer, the base film is bonded to the surface of the first pole piece and / or the second pole piece through the adhesive layer, and a part of the adhesive layer is embedded in a pit on the active material layer, and the embedding depth is H, and H satisfies: 0<H<2.5μm; And / or, the surface of a partial area of ​​the active material layer of the first pole piece and / or the second pole piece has a colloid, the area of ​​the active material layer having the colloid is S1, the total area of ​​the active material layer is S, and 12.5%<S1 / Stotal<95%.

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