Pole piece structure and battery cell

Abstract

The utility model belongs to the technical field of batteries, particularly relates to a pole piece structure and a battery cell, and solves the technical problems that the capacity of the battery cell is reduced and ions are separated out from the edge of a negative pole piece. The pole piece structure comprises a positive pole piece, a negative pole piece and a diaphragm, the positive pole piece and the negative pole piece extend along a first direction and are oppositely arranged along a second direction, and the diaphragm is arranged between the positive pole piece and the negative pole piece. The positive plate comprises a positive current collector, the negative plate comprises a negative current collector, at least one of the positive current collector and the negative current collector comprises a main body region and a thickened region, and the thickened region is located at least one of the two opposite ends of the main body region in the first direction and at least located on the side, adjacent to the diaphragm, of the main body region; the thickness of the edge of the positive current collector and / or the negative current collector is increased, so that the edge layering phenomenon of a positive plate, a diaphragm and a negative plate after hot pressing can be improved, and lithium precipitation at the edge of the negative plate is reduced.

Description

Technical Field

[0001] The embodiments of the utility model relate to the technical field of batteries, and in particular to a pole piece structure and a battery cell. Background Art

[0002] With the rapid development of economy and technology, power batteries are constantly updated. Lithium batteries are widely used in power, energy storage, digital and other fields because of their advantages such as high energy density, low self-discharge, high charging and discharging voltage platform, no memory effect, wide operating temperature range, fast charging and discharging, long cycle life and no environmental pollution.

[0003] The lithium battery includes a battery cell, which includes a shell, an electrolyte, a pole piece structure, a pole ear structure, etc. Among them, the pole piece structure includes a positive pole piece, a negative pole piece, and a separator arranged between the positive pole piece and the negative pole piece. The separator can prevent the positive pole piece and the negative pole piece from short-circuiting. The positive pole piece, the separator and the negative pole piece are wound or stacked in sequence. However, after the battery cell is hot-pressed, the positive pole piece, the separator and the negative pole piece are not well attached, and the distance between the positive pole piece and the negative pole piece is large, which makes the ion migration impedance of the battery cell larger during the charge and discharge process, reduces the capacity of the battery cell, and ions are precipitated at the edge of the negative pole piece. Utility Model Content

[0004] In view of the above problems, the embodiments of the present invention provide a pole piece structure and a battery cell to avoid the capacity of the battery cell being reduced and ions being precipitated at the edge of the negative pole piece.

[0005] The first aspect of the embodiment of the utility model provides a pole piece structure, which includes: a positive pole piece, a negative pole piece, and a separator arranged between the positive pole piece and the negative pole piece, wherein the positive pole piece and the negative pole piece both extend along a first direction and are arranged opposite to each other along a second direction, and the second direction intersects with the first direction;

[0006] The positive electrode sheet includes a positive electrode collector, the negative electrode sheet includes a negative electrode collector, at least one of the positive electrode collector and the negative electrode collector includes a main body region and a thickened region, the thickened region is located at least one of the two opposite ends of the main body region along the first direction, and is at least located on one side of the main body region adjacent to the diaphragm.

[0007] In some possible examples, along the first direction, an end surface of the thickened region is flush with a corresponding end surface of the main body region.

[0008] In some possible examples, along the end surface direction adjacent to the main body region, the thickness of the corresponding thickened region gradually increases.

[0009] In some possible examples, the main region and the thickened region of at least one of the positive electrode current collector and the negative electrode current collector have an arc transition.

[0010] In some possible examples, the radius of the arc is 10-20 mm.

[0011] In some possible examples, the positive electrode current collector and the negative electrode current collector both include a main body region and a thickened region, and along the first direction, the lengths of the thickened region of the positive electrode current collector and the thickened region of the negative electrode current collector are both 10-30 mm;

[0012] Along the second direction, the thickness of the thickened area of ​​the positive electrode current collector is less than or equal to 10 μm, and the thickness of the thickened area of ​​the negative electrode current collector is less than or equal to 5 μm.

[0013] In some possible examples, there are at least two negative electrode sheets and at least one positive electrode sheet. Along the second direction, the positive electrode sheets and the negative electrode sheets are arranged alternately in sequence, and a separator is arranged between any two adjacent positive electrode sheets and negative electrode sheets.

[0014] In some possible examples, the negative electrode sheets are located at the outermost sides relative to each other along the second direction, and a thickened area is provided on the side of the main areas of the two outermost negative electrode sheets opposite to each other, and the thickened areas are provided on both sides of the main areas of the remaining negative electrode sheets and the positive electrode sheets opposite to each other along the second direction.

[0015] In some possible examples, along the first direction, two ends of the separator protrude from two ends of the negative electrode current collector respectively, and a distance between corresponding ends of the separator and the negative electrode current collector is 1-2 mm;

[0016] And / or, along the third direction, two ends of the separator protrude from two ends of the negative electrode current collector respectively, and the distance between the corresponding ends of the separator and the negative electrode current collector is 1.5-5 mm, and the second direction intersects both the first direction and the second direction;

[0017] and / or, along the first direction, two ends of the negative electrode current collector protrude from two ends of the positive electrode current collector respectively, and a distance between corresponding ends of the negative electrode current collector and the positive electrode current collector is 1.5-3 mm;

[0018] And / or, along the third direction, two ends of the negative electrode current collector protrude from two ends of the positive electrode current collector respectively, and the distance between the corresponding ends of the negative electrode current collector and the positive electrode current collector is 1.25-2 mm, and the third direction intersects both the first direction and the second direction;

[0019] And / or, the positive electrode sheet further includes a positive electrode active material layer at least disposed on a side of the positive electrode collector facing the separator, and the negative electrode sheet further includes a negative electrode active material layer at least disposed on a side of the negative electrode collector facing the separator.

[0020] The pole piece structure of the embodiment of the utility model has at least the following advantages:

[0021] The electrode sheet structure in the embodiment of the utility model includes a positive electrode sheet, a negative electrode sheet and a separator, the positive electrode sheet and the negative electrode sheet both extend along the first direction and are arranged oppositely along the second direction, and the separator is arranged between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode collector, the negative electrode sheet includes a negative electrode collector, and at least one of the positive electrode collector and the negative electrode collector includes a main body area and a thickened area, and the thickened area is located at least one of the two opposite ends of the main body area along the first direction, and is at least located on one side of the main body area adjacent to the separator. By setting the thickened area, the thickness of the edge of the positive electrode collector and / or the negative electrode collector can be increased, so that the thickness of the positive electrode collector and / or the negative electrode collector can be adapted to the surface density of the active material to be coated, so as to improve the flatness of the edge after the positive electrode collector and / or the negative electrode collector is coated with the corresponding active material. In this way, the edge stratification phenomenon of the positive electrode sheet, separator and negative electrode sheet after hot pressing can be improved, and the misalignment phenomenon of the positive electrode sheet and the negative electrode sheet can be improved, the charge transfer impedance of ions during the charging and discharging process can be reduced, and lithium plating at the edge of the negative electrode sheet can be reduced.

[0022] The second aspect of the embodiment of the utility model further provides a battery cell, which includes the above-mentioned electrode structure. The battery cell includes the above-mentioned electrode structure, so it has at least the advantages of high capacity of the battery cell and less ion precipitation at the edge of the negative electrode. The specific effects are referred to above and will not be repeated here.

[0023] In addition to the technical problems solved by the embodiments of the utility model described above, the technical features that constitute the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions, other technical problems that can be solved by the pole piece structure and battery cell provided by the embodiments of the utility model, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail in the specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1It is a schematic diagram of the pole piece structure in the embodiment of the utility model;

[0026] Figure 2 Schematic diagram of the positive electrode current collector in the embodiment of the utility model;

[0027] Figure 3 Schematic diagram of the negative electrode current collector in the embodiment of the present utility model.

[0028] Description of reference numerals:

[0029] 10- positive electrode;

[0030] 11- positive electrode current collector;

[0031] 12- positive electrode active material layer;

[0032] 20- negative electrode sheet;

[0033] 21- negative electrode current collector;

[0034] 22- negative electrode active material layer;

[0035] 30 - diaphragm;

[0036] 40-main area;

[0037] 50-thickening area;

[0038] 60-Arc. DETAILED DESCRIPTION

[0039] In the related art, there are problems of reduced capacity of the battery cell and ion precipitation at the edge of the negative electrode sheet. The inventors have found that the reason is that in order to prevent the bulging of the edge after coating the active material, there is a thinning area of ​​active material at the edge of the positive electrode sheet and / or the negative electrode sheet, and the thinning area is chamfered. When the battery cell is hot-pressed, the thinning area is thinner and the pressure it is subjected to is weaker. The bonding effect of the positive electrode sheet, the diaphragm and the negative electrode sheet in this area is poor, and the positive electrode sheet, the diaphragm and the negative electrode sheet are not well attached, resulting in a large distance between the positive electrode sheet and the negative electrode sheet. The ion (such as lithium ion) migration impedance of the battery cell is large during the charge and discharge process, thereby reducing the capacity of the battery cell and precipitating ions at the edge of the negative electrode sheet.

[0040] In view of this, the embodiment of the utility model provides a pole piece structure, by setting a thickened area in the main area of ​​at least one of the positive current collector and the negative current collector, the thickened area is located at least one of the two ends of the main area opposite to each other along the first direction, and at least located on the side of the main area adjacent to the diaphragm, the thickness of the edge of the positive current collector and / or the negative current collector can be increased, so that the thickness of the positive current collector and / or the negative current collector can be adapted to the surface density of the active material to be coated, so as to improve the flatness of the edge of the positive current collector and / or the negative current collector after the corresponding active material is coated. In this way, the edge stratification phenomenon of the positive electrode sheet, the diaphragm and the negative electrode sheet after hot pressing can be improved, and the dislocation phenomenon of the positive electrode sheet and the negative electrode sheet can be improved, the charge transfer impedance of ions during the charging and discharging process can be reduced, and the lithium deposition at the edge of the negative electrode sheet can be reduced.

[0041] In order to make the above-mentioned purposes, features and advantages of the embodiments of the utility model more obvious and easy to understand, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the utility model.

[0042] See also Figures 1 to 3 The embodiment of the utility model provides a battery cell, which can be a soft-pack battery cell or a metal shell battery cell. The battery cell can be a cube, such as a cube or a cuboid; the battery cell can also be a cylinder, such as a cylinder or an elliptical cylinder.

[0043] The battery cell includes a shell, an electrolyte and a pole piece structure disposed in the shell, and a pole ear structure extending out of the shell. The shell provides support and protection for the structure inside it and facilitates the grouping of the battery cells. The electrolyte can transfer ions during the charging and discharging process of the battery cell, so that the battery cell can work normally. The pole ear structure is connected to the pole piece structure, and the pole ear structure includes a positive pole ear and a negative pole ear.

[0044] The electrode structure includes a positive electrode 10, a negative electrode 20, and a separator 30 disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10 and the negative electrode 20 extend along a first direction and are disposed opposite to each other along a second direction. The second direction intersects with the first direction, for example, is perpendicular to the first direction. The first direction is a length direction, such as Figure 1 The second direction is the thickness direction, as shown in Figure 1 The X direction shown in .

[0045] The positive electrode sheet 10 is electrically connected to the positive electrode ear, and the negative electrode sheet 20 is electrically connected to the negative electrode ear. The total number of positive electrode sheets 10 and negative electrode sheets 20 is not limited. Exemplarily, there are at least two negative electrode sheets 20 and at least one positive electrode sheet 10. All positive electrode sheets 10 and all negative electrode sheets 20 can be arranged alternately in sequence along the second direction to increase the energy density of the battery cell. A separator 30 is arranged between any adjacent positive electrode sheets 10 and negative electrode sheets 20, and the separator 30 can also be arranged on the outside of the positive electrode sheet 10 / negative electrode sheet 20.

[0046] In some possible examples, the number of positive electrode sheets 10 and negative electrode sheets 20 differs by one, such as Figure 1 As shown, there are three negative electrode sheets 20 and two positive electrode sheets 10. Along the second direction, the three negative electrode sheets 20 and the two positive electrode sheets 10 are arranged alternately in sequence. The separator 30 is arranged between the adjacent positive electrode sheets 10 and negative electrode sheets 20, and is also located on the side of the negative electrode sheets 20 that are away from each other. Along the second direction, the separator, the negative electrode sheet 20, the separator, the positive electrode sheet 10, the separator 30, the negative electrode sheet 20, and the separator 30 are arranged in sequence.

[0047] See also Figure 1 and Figure 2 The positive electrode sheet 10 includes a positive electrode current collector 11, which can be a metal foil. For example, the positive electrode current collector 11 is stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, titanium, etc. treated with silver surface. The positive electrode current collector 11 can also be a composite current collector, which is formed by forming a metal material on a polymer material substrate. The metal material can be aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc. The polymer material substrate can be polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.

[0048] The positive electrode sheet 10 further includes a positive electrode active material layer 12 disposed at least on one side of the positive electrode current collector 11 facing the separator 30. The positive electrode active material layer 12 includes a positive electrode main material region opposite to the main region 40 of the positive electrode current collector 11, and a positive electrode thinning material region corresponding to the thickened region 50 of the positive electrode current collector 11. In this way, the material surface density of the positive electrode active material layer 12 and the thickness of the positive electrode current collector 11 are inversely proportional, so that the total thickness of the positive electrode current collector 11 after coating the positive electrode active material layer 12 is consistent or close, that is, the thickness of the positive electrode sheet 10 is consistent or close along the first direction.

[0049] The material of the positive electrode active material layer 12 can be lithium-containing phosphate, lithium transition metal oxide and their respective modified compounds. Exemplarily, the material of the positive electrode active material layer 12 is at least one of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0050] The negative electrode sheet 20 includes a negative electrode current collector 21, which can be a metal foil, for example, the negative electrode current collector 21 is stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, titanium, etc. with silver surface treatment. The negative electrode current collector 21 can also be a foam metal, for example, the negative electrode current collector 21 is foam nickel, foam copper, foam aluminum or foam alloy. The negative electrode current collector 21 can also be a composite current collector, which is formed by forming a metal material on a polymer material substrate. The metal material can be copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc., and the polymer material substrate can be polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.

[0051] The negative electrode sheet 20 also includes a negative electrode active material layer 22 disposed at least on one side of the negative electrode current collector 21 facing the separator 30, and the negative electrode active material layer 22 includes a negative electrode main material area opposite to the main area 40 of the negative electrode current collector 21, and a negative electrode thinning material area corresponding to the thickening area 50 of the negative electrode current collector 21. In this way, the material surface density of the negative electrode active material layer 22 and the thickness of the negative electrode current collector 21 can be inversely proportional, so that the total thickness of the negative electrode current collector 21 after coating the negative electrode active material layer 22 is consistent or close, that is, the thickness of the negative electrode sheet 20 is consistent or close along the first direction. The material of the negative electrode active material layer 22 can be artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, etc.

[0052] In some possible examples, along the first direction, two ends of the separator 30 protrude from two ends of the negative electrode current collector 21, and the distance between the corresponding ends of the separator 30 and the negative electrode current collector 21 is 1-2 mm. Figure 1 As shown, the upper end of the separator 30 exceeds the upper end of the negative electrode current collector 21 by 1-2 mm, and the lower end of the separator 30 exceeds the lower end of the negative electrode current collector 21 by 1-2 mm.

[0053] In some possible examples, along the third direction, both ends of the separator 30 protrude from both ends of the negative electrode current collector 21, and the distance between the corresponding ends of the separator 30 and the negative electrode current collector 21 is 1.5-5 mm, and the second direction intersects both the first direction and the second direction, for example, is perpendicular. Figure 1 As shown, the third direction is a direction perpendicular to the paper surface, along which one end of the separator 30 extends beyond the corresponding end of the negative electrode current collector 21 by 1.5-5 mm, and the other end of the separator 30 extends beyond the corresponding end of the negative electrode current collector 21 by 1.5-5 mm.

[0054] It should be noted that, in the above example, the size of the separator 30 relative to the negative electrode current collector 21 along the first direction, and the size of the separator 30 relative to the negative electrode current collector 21 along the third direction, are determined according to the size of the negative electrode sheet 20 (for example, the negative electrode current collector 21), the degree of shrinkage of the separator 30 and the manufacturing level.

[0055] In some possible examples, along the first direction, two ends of the negative electrode current collector 21 protrude from two ends of the positive electrode current collector 11, and the distance between the corresponding ends of the negative electrode current collector 21 and the positive electrode current collector 11 is 1.25-2 mm. Figure 1 As shown, the upper end of the negative electrode current collector 21 exceeds the upper end of the positive electrode current collector 11 by 1.25-2 mm, and the lower end of the negative electrode current collector 21 exceeds the lower end of the positive electrode current collector 11 by 1.25-2 mm.

[0056] In some possible examples, along the third direction, the two ends of the negative electrode current collector 21 protrude from the two ends of the positive electrode current collector 11, and the distance between the corresponding ends of the negative electrode current collector 21 and the positive electrode current collector 11 is 1.5-3 mm, and the third direction intersects with both the first direction and the second direction, for example, perpendicularly. Figure 1 As shown, the third direction is a direction perpendicular to the paper surface, along which one end of the negative electrode current collector 21 extends beyond the corresponding end of the positive electrode current collector 11 by 1.5-3 mm, and the other end of the negative electrode current collector 21 extends beyond the corresponding end of the positive electrode current collector 11 by 1.5-3 mm.

[0057] It should be noted that in the above example, the size of the negative electrode collector 21 relative to the positive electrode collector 11 along the first direction, and the size of the negative electrode collector 21 relative to the positive electrode collector 11 along the third direction, are determined according to the size of the positive electrode sheet 10 (for example, the positive electrode collector 11), the size of the negative electrode sheet 20 (for example, the negative electrode collector 21), the cutting and lamination levels, etc.

[0058] Continue reading Figures 1 to 3 , at least one of the positive current collector 11 and the negative current collector 21 includes a main region 40 and a thickened region 50, the thickened region 50 is located at least one of the two ends of the main region 40 opposite to each other along the first direction, and is at least located on one side of the main region 40 adjacent to the separator 30. Exemplarily, both the positive current collector 11 and the negative current collector 21 include a main region 40 and a thickened region 50. The thickened region 50 of the positive current collector 11 is correspondingly arranged in the main region 40 of the positive current collector 11, and the thickened region 50 of the negative current collector 21 is correspondingly arranged in the main region 40 of the negative current collector 21. In this way, the thickness of the edge of the positive electrode sheet 10 increases, and the thickness of the edge of the negative electrode sheet 20 also increases.

[0059] By setting the thickened area 50, the thickness of the edge of the positive current collector 11 and / or the negative current collector 21 can be increased, so that the thickness of the positive current collector 11 and / or the negative current collector 21 can be adapted to the surface density of the active material to be coated, so as to improve the flatness of the edge after the positive current collector 11 and / or the negative current collector 21 is coated with the corresponding active material. In this way, the edge stratification phenomenon of the positive electrode sheet 10, the separator 30 and the negative electrode sheet 20 after hot pressing can be improved, and the misalignment phenomenon of the positive electrode sheet 10 and the negative electrode sheet 20 can be improved, the charge transfer impedance of ions during the charging and discharging process can be reduced, and the lithium precipitation at the edge of the negative electrode sheet 20 can be reduced. In addition, the thickened area 50 is set at the end of the main area 40, which can also improve the electrochemical properties of the material at the edge of the battery cell, reduce the probability of environmental foreign matter entering during the trial production of the electrode structure, and increase the cycle performance and safety factor of the battery cell.

[0060] Among them, the thickened area 50 is located at one end of the main area 40, or the thickened area 50 is located at both ends of the main area 40, that is, along the first direction, the thickened area 50 is adjacent to the end of the main area 40 and staggered with the center of the main area 40. Specifically, the thickened area 50 of the positive current collector 11 is arranged at both ends or one end of the main area 40 of the positive current collector 11, and / or the thickened area 50 of the negative current collector 21 is arranged at both ends or one end of the main area 40 of the negative current collector 21. Along the third direction, the two ends of the thickened area 50 are respectively aligned with the two ends of the main area 40 where it is located, that is, the width of the thickened area 50 and the corresponding main area 40 are equal.

[0061] The thickened area 50 is arranged at one or both ends of the main body area 40, which can be determined according to the connection mode between the pole piece structure and the pole ear structure. Exemplarily, when both opposite ends of the pole piece structure along the first direction are connected to the pole ear structure, both opposite ends of the main body area 40 along the first direction are provided with thickened areas 50. When one of the two opposite ends of the pole piece structure along the first direction is connected to the pole ear structure, one of the two opposite ends of the main body area 40 along the first direction is provided with a thickened area 50, and the thickened area 50 is adjacent to the pole ear structure.

[0062] In the example where both the positive current collector 11 and the negative current collector 21 include the main region 40 and the thickened region 50, along the first direction, the length of the thickened region 50 of the positive current collector 11 and the thickened region 50 of the negative current collector 21 are both 10-30 mm. Along the second direction, the thickness of the thickened region 50 of the positive current collector 11 is less than or equal to 10 μm, and the thickness of the thickened region 50 of the negative current collector 21 is less than or equal to 5 μm.

[0063] In some possible examples, along the end surface direction adjacent to the main body region 40, the thickness of the corresponding thickened region 50 gradually increases. Figure 2As shown, the thickness of the thickened region 50 gradually increases along the direction from the center of the main region 40 to the end of the main region 40, that is, the thickness of the positive electrode current collector 11 gradually increases along the edge direction adjacent to the positive electrode current collector 11. The thickened region 50 may be sloped, with the thin end of the thickened region 50 adjacent to the center of the main region 40 and the thick end of the thickened region 50 adjacent to the end of the main region 40.

[0064] Along the first direction, the end face of the thickened area 50 is flush with the corresponding end face of the main area 40, wherein the end face of the thickened area 50 and the corresponding end face of the main area 40 refer to the end faces of the thickened area 50 and the main area 40 that are located on the same side and adjacent to each other. For example, the thickened area 50 is located at the upper end of the main area 40, and the upper end face of the thickened area 50 corresponds to the upper end face of the main area 40; the thickened area 50 is located at the lower end of the main area 40, and the lower end face of the thickened area 50 corresponds to the lower end face of the main area 40.

[0065] For example, Figure 2 and Figure 3 As shown, thickened areas 50 are provided at both the upper and lower ends of the main area 40. The upper end surface of the thickened area 50 located at the upper end of the main area 40 is aligned with the upper end surface of the main area 40, and the lower end surface of the thickened area 50 located at the lower end of the main area 40 is aligned with the lower end surface of the main area 40.

[0066] In some possible examples, the thickness of the main region 40 may be 10-15 μm, and the thickened region 50 is related to its location. Among them, along the second direction, the thickness of the thickened region 50 of the positive current collector 11 is less than or equal to 10 μm. The thickness of the thickened region 50 of the positive current collector 11 is adjusted according to the solid content, viscosity and coating surface density of the positive active material layer 12. The thickness of the thickened region 50 of the negative current collector 21 is less than or equal to 5 μm, and the thickness of the thickened region 50 of the positive and negative current collectors 21 is adjusted according to the solid content, viscosity and coating surface density of the negative active material layer 22.

[0067] Continue reading Figure 2 and Figure 3 The arc 60 transitions between the main area 40 and the thickened area 50 of at least one of the positive current collector 11 and the negative current collector 21, and the radius of the arc 60 is 10-20 mm. In this way, the smoothness of the positive current collector 11 and / or the negative current collector 21 can be improved, the sharp edges can be reduced, and the manufacturing is convenient.

[0068] Exemplarily, the connection between the main area 40 of the positive current collector 11 and the thickened area 50 of the positive current collector 11 is a transition of an arc 60, that is, the thin end of the thickened area 50 of the positive current collector 11 and the connection of the main area 40 of the positive current collector 11 are transitioned by an arc 60, and the radius of the arc 60 is 10-20 mm. The connection between the main area 40 and the thickened area 50 of the negative current collector 21 is a transition of an arc 60, that is, the thin end of the thickened area 50 of the negative current collector 21 and the connection of the main area 40 of the negative current collector 21 are transitioned by an arc 60, and the radius of the arc 60 is 10-20 mm.

[0069] Continue reading Figure 1 , the thickened area 50 is at least located on one side of the main area 40 adjacent to the diaphragm 30, wherein when the main area 40 has a diaphragm 30 on one side, the thickened area 50 is located on the side of the main area 40 adjacent to the diaphragm 30, and when the main area 40 has diaphragms 30 on both sides, the thickened area 50 is provided on both sides of the main area 40. Figure 1 As shown, a thickened area 50 is provided on the left and right sides of each main body area 40 .

[0070] In some possible examples, there are at least two negative electrode sheets 20, and there is at least one positive electrode sheet 10. The negative electrode sheets 20 are located at the outermost sides opposite to each other along the second direction. The sides of the main regions 40 of the two outermost negative electrode sheets 20 opposite to each other are provided with a thickened region 50, and the two sides of the main regions 40 of the remaining negative electrode sheets 20 and the positive electrode sheets 10 opposite to each other along the second direction are provided with a thickened region 50. The surfaces of the two outermost negative electrode sheets 20 facing away from each other (i.e., the outer surfaces) do not correspond to the positive electrode sheet 10, and the surfaces of the two negative electrode sheets 20 facing away from each other do not need to be provided with a thickened region 50, and the remaining negative electrode sheets 20 and the positive electrode sheets 10 are provided with a thickened region 50 on both sides.

[0071] It can be understood that when there are two negative electrode sheets 20, the surfaces of the main regions 40 of the two negative electrode sheets 20 facing each other are respectively provided with thickened regions 50, and the surfaces on both sides of the main region 40 of the positive electrode sheet 10 between the two negative electrode sheets 20 are respectively provided with thickened regions 50. When there are three or more negative electrode sheets 20, the surfaces of the main regions 40 of the two outermost negative electrode sheets 20 facing each other are respectively provided with thickened regions 50, the surfaces on both sides of the main regions 40 of the remaining negative electrode sheets 20 are respectively provided with thickened regions 50, and the surfaces on both sides of the main region 40 of each positive electrode sheet 10 are respectively provided with thickened regions 50.

[0072] In summary, the electrode sheet structure of the embodiment of the utility model includes a positive electrode sheet 10, a negative electrode sheet 20 and a separator 30, the positive electrode sheet 10 and the negative electrode sheet 20 are both extended along the first direction and arranged oppositely along the second direction, and the separator 30 is arranged between the positive electrode sheet 10 and the negative electrode sheet 20. The positive electrode sheet 10 includes a positive electrode collector 11, the negative electrode sheet 20 includes a negative electrode collector 21, at least one of the positive electrode collector 11 and the negative electrode collector 21 includes a main body area 40 and a thickening area 50, and the thickening area 50 is located at least one of the two opposite ends of the main body area 40 along the first direction, and at least located on one side of the main body area 40 adjacent to the separator 30. By providing the thickened area 50, the thickness of the edge of the positive electrode collector 11 and / or the negative electrode collector 21 can be increased, so that the thickness of the positive electrode collector 11 and / or the negative electrode collector 21 can be adapted to the surface density of the active material to be coated, so as to improve the flatness of the edge after the positive electrode collector 11 and / or the negative electrode collector 21 is coated with the corresponding active material. In this way, the edge stratification phenomenon of the positive electrode sheet 10, the separator 30 and the negative electrode sheet 20 after hot pressing can be improved, and the misalignment phenomenon of the positive electrode sheet 10 and the negative electrode sheet 20 can be improved, the charge transfer impedance of ions during the charging and discharging process can be reduced, and the lithium deposition at the edge of the negative electrode sheet 20 can be reduced.

[0073] The various embodiments or implementation methods in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referenced to each other.

[0074] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred system or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0075] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A pole piece structure, characterized in that: include: A positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet, wherein the positive electrode sheet and the negative electrode sheet both extend along a first direction and are disposed opposite to each other along a second direction, and the second direction intersects the first direction; The positive electrode sheet includes a positive electrode collector, the negative electrode sheet includes a negative electrode collector, at least one of the positive electrode collector and the negative electrode collector includes a main body region and a thickened region, the thickened region is located at least one of the two opposite ends of the main body region along the first direction, and is at least located on one side of the main body region adjacent to the diaphragm.

2. The pole piece structure according to claim 1, characterized in that: Along the first direction, an end surface of the thickened area is flush with a corresponding end surface of the main body area.

3. The pole piece structure according to claim 1, characterized in that: Along the end surface direction adjacent to the main body area, the thickness of the corresponding thickened area gradually increases.

4. The pole piece structure according to claim 1, characterized in that: The main area and the thickened area of ​​at least one of the positive electrode current collector and the negative electrode current collector have an arc transition.

5. The pole piece structure according to claim 4, characterized in that: The radius of the arc is 10-20 mm.

6. The pole piece structure according to any one of claims 1 to 5, characterized in that: The positive electrode current collector and the negative electrode current collector both include a main body region and a thickened region, and along the first direction, the lengths of the thickened region of the positive electrode current collector and the thickened region of the negative electrode current collector are both 10-30 mm; Along the second direction, the thickness of the thickened area of ​​the positive electrode current collector is less than or equal to 10 μm, and the thickness of the thickened area of ​​the negative electrode current collector is less than or equal to 5 μm.

7. The pole piece structure according to any one of claims 1 to 5, characterized in that: There are at least two negative electrode sheets and at least one positive electrode sheet. Along the second direction, the positive electrode sheets and the negative electrode sheets are arranged alternately in sequence, and a separator is arranged between any two adjacent positive electrode sheets and negative electrode sheets.

8. The pole piece structure according to claim 7, characterized in that: The negative electrode sheets are located at the outermost sides relative to each other along the second direction, and a thickened area is provided on the side of the main areas of the two outermost negative electrode sheets opposite to each other, and the thickened areas are provided on both sides of the main areas of the remaining negative electrode sheets and the positive electrode sheets opposite to each other along the second direction.

9. The pole piece structure according to any one of claims 1 to 5, characterized in that: Along the first direction, two ends of the separator protrude from two ends of the negative electrode current collector respectively, and the distance between the corresponding ends of the separator and the negative electrode current collector is 1-2 mm; And / or, along the third direction, two ends of the separator protrude from two ends of the negative electrode current collector respectively, and the distance between the corresponding ends of the separator and the negative electrode current collector is 1.5-5 mm, and the second direction intersects both the first direction and the second direction; and / or, along the first direction, two ends of the negative electrode current collector protrude from two ends of the positive electrode current collector respectively, and a distance between corresponding ends of the negative electrode current collector and the positive electrode current collector is 1.5-3 mm; And / or, along the third direction, two ends of the negative electrode current collector protrude from two ends of the positive electrode current collector respectively, and the distance between the corresponding ends of the negative electrode current collector and the positive electrode current collector is 1.25-2 mm, and the third direction intersects both the first direction and the second direction; And / or, the positive electrode sheet further includes a positive electrode active material layer at least disposed on a side of the positive electrode collector facing the separator, and the negative electrode sheet further includes a negative electrode active material layer at least disposed on a side of the negative electrode collector facing the separator.

10. A battery cell, characterized in that: Comprising the pole piece structure as described in any one of claims 1-9.

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