Battery cell and battery

Abstract

The invention provides a battery cell and a battery, and the battery cell comprises a positive plate which comprises a positive current collector and positive active material layers respectively arranged on at least one side of the positive current collector; the negative plate comprises a negative current collector and negative active material layers arranged on two opposite sides of the negative current collector; the diaphragms are positioned between the adjacent positive plates and negative plates; at least one groove group is formed in the side surface, deviating from the negative electrode current collector, of the negative electrode active material layer, the groove group at least comprises a first groove and a second groove, the width of the first groove is greater than that of the second groove, and / or the depth of the first groove is greater than that of the second groove. The lithium ion intercalation and deintercalation rate is improved, and the capacity and the energy density of the battery are further improved.

Description

Technical Field

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

[0002] With the advent of the 5G era and the rapid development of lithium-ion battery technology, people have put forward higher requirements on the energy density, fast charging capability and charge and discharge rate of lithium-ion batteries.

[0003] During the process of conceiving and implementing this application, the applicant discovered that there are at least the following problems: during the charging and discharging process of lithium-ion batteries, due to the large surface compaction of the negative electrode sheet, lithium ions are difficult to embed into and out of the inner active material layer, resulting in a waste of active materials and the inability to fully utilize the negative electrode capacity of the battery.

[0004] The preceding description is intended to provide general background information and does not necessarily constitute prior art. Summary of the Invention

[0005] The present application provides a battery cell and a battery, which improve the rate of lithium ion insertion and extraction, thereby increasing the capacity and energy density of the battery.

[0006] The present application provides a battery cell, comprising:

[0007] A positive electrode sheet, comprising a positive electrode current collector and a positive electrode active material layer respectively arranged on at least one side of the positive electrode current collector;

[0008] A negative electrode sheet, comprising a negative electrode current collector and a negative electrode active material layer disposed on opposite sides of the negative electrode current collector;

[0009] A diaphragm, which is located between adjacent positive and negative electrode sheets;

[0010] At least one groove group is formed on the side of the negative electrode active material layer facing away from the negative electrode current collector, and the groove group includes at least a first groove and a second groove, the width of the first groove is greater than the width of the second groove, and / or the depth of the first groove is greater than the depth of the second groove;

[0011] There are multiple first grooves and multiple second grooves; within a unit area, the number of the first grooves is smaller than the number of the second grooves.

[0012] Through the above-mentioned arrangement, that is, by opening two types of grooves of different depths and widths on the negative electrode active material layer, and within a unit area, the number of the first grooves is smaller than the number of the second grooves, it is helpful to achieve a more balanced electrochemical reaction rate in the negative electrode active material layer, and to provide lithium ions with sufficient and deep enough channels to enter the negative electrode active material layer while meeting the battery safety and capacity. This can improve the utilization rate of the active material, ensure a more uniform distribution of lithium ions, increase the capacity and energy density of the battery, and thus improve the cycle stability of the battery.

[0013] In some optional embodiments, the extending direction of the groove group is parallel to the extending direction of the negative electrode sheet; or,

[0014] There is an angle A between the extension direction of the groove group and the extension direction of the negative electrode sheet, which satisfies: A≤15°. It should be noted that the extension direction of the groove group is consistent with the negative electrode sheet, which reduces the path resistance of ion transmission, improves the conductivity of the battery, and reduces the difficulty and cost of implementation; the existence of the angle can increase the diffusion path length of lithium ions in the negative electrode active material layer, help to improve the diffusion uniformity of lithium ions, reduce the excessive concentration of ions in a certain direction, and thus improve the overall performance of the battery.

[0015] In some optional embodiments, the width W1 of the first groove satisfies: W1 ≥ 5 μm; and / or,

[0016] The width W2 of the second groove satisfies: 0.1 μm≤W2≤5 μm; and / or,

[0017] The difference between the width W1 of the first groove and the width W2 of the second groove satisfies: 0.1 μm≤W1-W2≤30 μm.

[0018] It should be noted that the larger width allows more lithium ions to pass through, thereby improving ion transport efficiency. This helps achieve faster reactions during charging and discharging. The narrower second groove provides a fine ion channel, which helps achieve more uniform ion distribution and reduce local overreaction.

[0019] In some optional embodiments, the depth H1 of the first groove satisfies: 4 μm ≤ H1 ≤ 20 μm; and / or,

[0020] The depth H2 of the second groove satisfies: 0.1 μm ≤ H2 ≤ 4 μm; and / or,

[0021] The difference between the depth H1 of the first groove and the depth H2 of the second groove satisfies:

[0022] 0.1μm≤H1-H2≤20μm.

[0023] It should be noted that the deeper first grooves allow lithium ions to penetrate deeper into the negative electrode active material layer, thereby improving ion transport efficiency. The shallower second grooves provide fine ion channels, enabling more uniform ion distribution and reducing local overreaction.

[0024] In some optional embodiments,

[0025] The number of first grooves L1 per unit area and the width H3 of the negative electrode sheet satisfy the following conditions: L1 / H3mm≥1 / 3(mm -1 ); and / or,

[0026] The number of second grooves L2 per unit area and the width H3 of the negative electrode sheet satisfy the following conditions: L2 / H3mm≥10 / 3(mm -1 ).

[0027] It should be noted that there must be a sufficient number of first grooves across the width of the negative electrode sheet to provide effective lithium ion rapid transmission channels, and a higher second groove density ensures that there are sufficient channels on the negative electrode sheet to achieve uniform ion distribution.

[0028] In some optional embodiments, along the width direction of the negative electrode sheet, the distance W3 between the first groove and the second groove satisfies: 2 μm≤W3≤80 μm; and / or,

[0029] Along the width direction of the negative electrode sheet, the difference between the distance between a first groove and an adjacent second groove and the distance between a first groove and an adjacent first groove is less than 10 μm; and / or,

[0030] Along the width direction of the negative electrode sheet, a difference between a distance between a second groove and an adjacent first groove and a distance between a second groove and an adjacent second groove is less than 10 μm.

[0031] It should be noted that reasonable groove spacing ensures that there are sufficient transmission paths for lithium ions in the negative electrode active material layer, which helps to optimize ion transmission efficiency and reduce ion transmission resistance.

[0032] In some optional embodiments, the negative electrode sheet includes an active layer and a hollow foil area;

[0033] The active layer is provided with a groove group.

[0034] It should be noted that such a configuration can provide a sufficiently large area of ​​channels for lithium ions to be deintercalated from the negative electrode active material layer in the negative electrode sheet.

[0035] In some optional embodiments, there is an interface between the hollow foil area and the active layer;

[0036] On the front side of the negative electrode sheet, the distance W4 between the end of the groove group and the junction end satisfies: 0.5 mm ≤ W4 ≤ 6 mm; and / or,

[0037] On the back side of the negative electrode sheet, the distance W5 between the end of the groove group and the junction end satisfies: 0.5 mm ≤ W5 ≤ 6 mm.

[0038] It should be noted that the above-mentioned setting can reduce the risk of electrode cycle breakage and internal short circuit of the battery.

[0039] In some optional embodiments, when the battery cell is a wound core, along the length direction of the negative electrode sheet 120, the distance W6 between the head end of the groove group and the head end of the negative electrode sheet satisfies: 0.5mm≤W6≤6mm.

[0040] It should be noted that, in the actual production process, multiple negative electrode sheets are continuous with each other. To prevent the foil of the previous negative electrode sheet from being scratched, it is necessary to limit the distance between the head end of the groove group and the head end of the negative electrode sheet.

[0041] In some optional embodiments, the width of the negative electrode sheet is greater than the width of the positive electrode sheet;

[0042] In the width direction, the distance W7 between the notch of the groove group located at the top end of the negative electrode sheet and the top edge of the negative electrode sheet satisfies: 0.5 mm≤W7≤5 mm.

[0043] It should be noted that in order to prevent lithium ion deposition due to a lack of an embedded layer during charging and discharging, the battery must be designed to ensure that the width of the negative electrode is greater than that of the positive electrode.

[0044] The present application also provides a battery, comprising the battery cell as described above.

[0045] The present application also provides a battery cell and a battery, wherein the battery cell includes a positive electrode sheet, including a positive electrode current collector and a positive electrode active material layer respectively arranged on at least one side of the positive electrode current collector; a negative electrode sheet, including a negative electrode current collector and a negative electrode active material layer arranged on opposite sides of the negative electrode current collector; a separator, and the separator is located between adjacent positive electrode sheets and negative electrode sheets; at least one groove group is provided on the side of the negative electrode active material layer facing away from the negative electrode current collector, and the groove group includes at least a first groove and a second groove, the width of the first groove is greater than the width of the second groove and / or the depth of the first groove is greater than the depth of the second groove.

[0046] By providing two types of grooves of different depths and widths on the negative electrode active material layer, and with the number of first grooves being smaller than the number of second grooves per unit area, a more balanced electrochemical reaction rate is achieved within the negative electrode active material layer. This allows lithium ions to enter the negative electrode active material layer through sufficient and deep channels while ensuring battery safety and capacity. This improves the utilization rate of the active material, ensures a more uniform distribution of lithium ions, increases the battery's capacity and energy density, and thus improves the battery's cycle stability. Furthermore, by providing fewer first grooves (wider and deeper) within the groove group, a primary rapid transmission channel for lithium ions can be provided. These first grooves can effectively reduce ion transmission resistance and improve the battery's charge and discharge efficiency.

[0047] Due to the large number of second grooves (narrower and shallower), they can provide more uniform ion distribution channels throughout the negative electrode active material layer. This helps reduce local overreaction, lowers the risk of thermal runaway of the battery, and improves the safety and stability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] 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 labor.

[0049] Figure 1 A schematic diagram of the structure of a battery cell provided in an embodiment of the present application;

[0050] Figure 2 A cross-sectional view of a battery cell provided in an embodiment of the present application;

[0051] Figure 3 A cross-sectional view of the negative electrode sheet in the battery cell provided in an embodiment of the present application;

[0052] Figure 4 A schematic diagram of a structure of a groove group in a battery cell provided in an embodiment of the present application;

[0053] Figure 5 A cross-sectional view of the front side of a negative electrode sheet in a battery cell provided in an embodiment of the present application;

[0054] Figure 6 A cross-sectional view of the back side of a negative electrode sheet in a battery cell provided in an embodiment of the present application;

[0055] Figure 7 A cross-sectional view of the negative electrode sheet in the second battery cell provided in an embodiment of the present application;

[0056] Figure 8A schematic diagram of the partial structure of the groove group in the battery cell provided in an embodiment of the present application.

[0057] Description of reference numerals:

[0058] 100-battery cells;

[0059] 110 - positive electrode sheet; 111 - positive electrode current collector; 112 - positive electrode active material layer;

[0060] 120 - negative electrode sheet; 121 - negative electrode current collector; 122 - negative electrode active material layer; 123 - double-sided area; 124 - single-sided area; 125 - empty foil area;

[0061] 130-diaphragm;

[0062] 140 - groove group; 141 - first groove; 142 - second groove. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. All other embodiments obtained are within the scope of protection of this application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0064] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present application.

[0065] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be interpreted broadly. For example, they may refer to fixed connections, detachable connections, or integration; they may refer to direct connections or indirect connections through an intermediate medium; they may refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0066] It should be noted that, in the description of this application, the terms "first," "second," and "third" are used solely to facilitate the description of different components and should not be understood to indicate or imply a sequential relationship, relative importance, or implicitly specify the number of technical features being referred to. Therefore, features specified as "first," "second," or "third" may explicitly or implicitly include at least one of these features.

[0067] At present, during the charging and discharging process of lithium-ion batteries, due to the large surface compaction of the negative electrode sheet, lithium ions are difficult to embed into and out of the inner active material layer, resulting in a waste of active materials and the inability to fully utilize the battery's negative electrode capacity.

[0068] Practice has proven that the existing negative electrode marking process can effectively utilize the negative electrode active material. However, in the actual production process, the existing marking process has the following problems: to ensure the smoothness of the actual production process and control the production process cost, the marking device cannot be modified once the operating parameters are set. This makes the line pits produced by the existing marking technology relatively consistent, and can only generate line pits of equal depth and spacing at the same time. In order to ensure that the active material layer in the inner layer of the negative electrode sheet can participate in the insertion and extraction of lithium ions, it is necessary to ensure that the line pits reach a sufficient depth to provide a deeper channel for lithium ions.

[0069] However, the deep pits in the prior art will lead to excessive loss of negative electrode active materials, which in turn will cause greater loss of battery capacity.

[0070] In addition, due to the problem of process tolerance, in order to prevent the overlap of the wire pits, which will cause excessive loss of active materials in local areas, or even scratch the metal current collector, which will have a significant impact on battery performance and safety, the spacing between the wire pits in the existing technology is relatively wide, which means that in the same area, the wire pits occupy a smaller area, the lithium ion embedding channels are reduced, and the uniformity of the lithium ion embedding channels is reduced. A large number of lithium ions cannot pass through the wire pits to enter the inner layer active materials because they are far away from the wire pits. There is still a large amount of inner layer active materials that cannot participate in the lithium ion embedding and extraction process, resulting in capacity loss.

[0071] In order to overcome the defects in the prior art, the battery cell and battery provided in the present application, by opening two grooves of different depths and widths on the negative electrode active material layer, help to achieve a more balanced electrochemical reaction rate in the negative electrode active material layer, and can provide lithium ions with sufficient and deep enough channels to enter the negative electrode active material layer while meeting the battery safety and capacity. It can improve the utilization rate of the active material, ensure a more uniform distribution of lithium ions, increase the capacity and energy density of the battery, and thus improve the cycle stability of the battery.

[0072] The contents of this application will be described in detail below with reference to the accompanying drawings so that those skilled in the art can understand the contents of this application more clearly and in detail.

[0073] Figure 1 This is a schematic diagram of the structure of the battery cell provided in the embodiment of the present application. Figure 2 A cross-sectional view of a battery cell provided in an embodiment of the present application. Figure 3 This is a cross-sectional view of the negative electrode sheet in the battery cell provided in an embodiment of the present application.

[0074] like Figures 1 to 3 As shown, an embodiment of the present application provides a battery cell 100, including:

[0075] The positive electrode sheet 110 includes a positive electrode current collector 111 and a positive electrode active material layer 112 disposed on at least one side of the positive electrode current collector 111;

[0076] The negative electrode sheet 120 includes a negative electrode current collector 121 and negative electrode active material layers 122 disposed on opposite sides of the negative electrode current collector 121;

[0077] The separator 130 is located between the adjacent positive electrode sheet 110 and the negative electrode sheet 120;

[0078] At least one groove group 140 is defined on the side of the negative active material layer 122 facing away from the negative current collector 121. The groove group 140 includes at least a first groove 141 and a second groove 142. The width of the first groove 141 is greater than the width of the second groove 142, and / or the depth of the first groove 141 is greater than the depth of the second groove 142. There are multiple first grooves 141 and multiple second grooves 142. Within a unit area, the number of first grooves 141 is less than the number of second grooves 142.

[0079] It should be noted that there need to be enough groove groups 140 on the surface of the negative electrode sheet 120 for lithium ions to enter the inner layer of active material. In order to prevent excessive loss of active material, the number of lines of the second grooves 142 per unit area must be greater than the number of lines of the first grooves 141, which can increase the uniformity of the lithium ion channels.

[0080] In some embodiments, the first groove 141 and the second groove 142 in the embodiment of the present application need to meet different widths and depths respectively.

[0081] It should be noted that, herein, within a unit area refers to selecting a sample area of ​​100 μm*100 μm in the negative electrode sheet 120 , or 1 mm*1 mm in the negative electrode sheet 120 .

[0082] It should be noted that by providing fewer first grooves 141 (wider and deeper) in the groove group 140, a main rapid transmission channel for lithium ions can be provided. These first grooves 141 can effectively reduce ion transmission resistance and improve the charge and discharge efficiency of the battery.

[0083] Since there are a large number of second grooves 142 (narrower and shallower), they can provide more uniform ion distribution channels throughout the negative electrode active material layer 122. This helps reduce local overreaction, lowers the risk of thermal runaway of the battery, and improves the safety and stability of the battery.

[0084] Through the above-mentioned setting, that is, by opening two grooves of different depths and widths on the negative electrode active material layer 122, it is helpful to achieve a more balanced electrochemical reaction rate in the negative electrode active material layer 122, and to provide lithium ions with sufficient and deep enough channels to enter the negative electrode active material layer 122 while meeting the battery safety and capacity. This can improve the utilization rate of the active material, ensure a more uniform distribution of lithium ions, increase the capacity and energy density of the battery, and thus improve the cycle stability of the battery.

[0085] Specifically, the first groove 141 with a wider width and a deeper depth allows lithium ions to pass through the negative electrode active material layer 122 relatively easily and be deintercalated in the inner active material of the negative electrode sheet 120. If the first groove 141 is used alone, it will cause excessive loss of the negative electrode active material layer 122. Therefore, adding the second groove 142 with a narrower width and a shallower depth also provides a new channel for lithium ions to enter the inner active material, thereby improving the uniformity of lithium ions being deintercalated from the negative electrode active material layer 122, improving the transmission efficiency of lithium ions, and reducing the internal resistance of the battery.

[0086] It should be noted that the relevant structure will be described in detail below.

[0087] It should be noted that the positive electrode sheet 110 , the separator 130 and the negative electrode sheet 120 are stacked together in sequence and then wound from the starting end to the ending end to form a roll core structure of the lithium-ion battery.

[0088] The positive electrode sheet 110 is located at the outermost side of the core structure. Of course, the positive electrode sheet 110, the separator 130 and the negative electrode sheet 120 are stacked in sequence to form a flat battery cell 100 structure. The specific electrodes can be referred to above.

[0089] It should be noted that the preparation of the positive electrode sheet 110 is as follows: lithium cobalt oxide, a conductive agent (a mixture of conductive carbon black and carbon nanotubes), and PVDF are placed in NMP at a mass ratio of 97.60:1.35:1.05, and stirred evenly to obtain a positive electrode slurry; the positive electrode slurry is evenly coated on the front and back sides of an aluminum foil, with a coating surface density of 0.01704 g / cm2; and the positive electrode sheet 110 is obtained by drying and rolling.

[0090] Preparation of the negative electrode sheet 120: Silicon-carbon composite material, conductive carbon black, styrene-butadiene rubber, and sodium carboxymethyl cellulose are placed in deionized water in a mass ratio of 97.2:0.5:1.3:1, wherein the silicon-carbon composite material is mixed with the above slurry and stirred evenly to obtain a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode collector 121, and then dried, rolled, and slit in sequence to obtain the negative electrode sheet 120 after sheeting.

[0091] Battery Preparation: The separator 130 of this application uses a substrate + ceramic + glue-coated separator 130. The electrolyte includes lithium salt LiPF6 and a solvent. The solvent includes ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC), wherein the molar ratio of the three is DEC:EC:EMC = 1:1:1. The above-cut positive electrode sheet 110, separator 130, and negative electrode sheet 120 are stacked in sequence and wound into a wound-type battery cell 100. After packaging, liquid injection, formation, and secondary sealing, the battery cell 100 is produced.

[0092] In some embodiments, the current collector includes but is not limited to foils made of metal materials such as gold, silver, copper, iron, tin, zinc, lead, nickel, aluminum, tungsten, molybdenum, tantalum, niobium, titanium, steel and stainless steel, nickel-based and cobalt-based alloys, and the foil thickness is between 1 μm and 30 μm.

[0093] Non-metallic current collectors include, but are not limited to, conductive foils with a thickness of 1 μm to 30 μm, made from a polymer film substrate made of PP, PET, PE, PA, or PI, and plated with a conductive material such as gold, silver, copper, iron, tin, zinc, lead, nickel, aluminum, tungsten, molybdenum, tantalum, niobium, titanium, or carbon. In some optional embodiments, the battery is a laminated battery, comprising a laminated cell 100, which includes a stacked positive electrode sheet 110, a negative electrode sheet 120, and a separator 130.

[0094] It should be noted that the number of positive electrode sheets 110 is at least three, and the positive electrode sheets 110 include two single-sided positive electrode sheets 110 located on the outermost sides of the battery cell 100 and a double-sided positive electrode sheet 110 located between the two single-sided positive electrode sheets 110. The single-sided positive electrode sheet 110 includes a positive electrode current collector 111 and a positive electrode active material layer 112 arranged on one side surface of the positive electrode current collector 111. The double-sided positive electrode sheet 110 includes a positive electrode current collector 111 and positive electrode active material layers 112 respectively arranged on the opposite side surfaces of the positive electrode current collector 111.

[0095] There are at least two negative electrode sheets 120 , and the negative electrode sheet 120 is located between two adjacent positive electrode sheets 110 ; the separator 130 is located between the positive electrode sheet 110 and the negative electrode sheet 120 .

[0096] It should be noted that the first groove 141 and the second groove 142 are formed on the surface of the negative electrode sheet 120 by physical grinding.

[0097] Among them, the specific implementation method of "physical grinding" is to make the negative electrode sheet 120 pass through the surface of a sand roller with a certain roughness during movement, adjust the speed of the sand roller to form a differential speed between the negative electrode sheet 120 and the sand roller, and use the rough sand roller to grind off the negative electrode active material in the surface negative electrode active material layer 122.

[0098] The effect of physical polishing is that unevenly distributed first grooves 141 and second grooves 142 appear on the surface of the negative electrode sheet 120. It should be noted that the width of the first groove 141 is wider than the width of the second groove 142, and the depth of the first groove 141 is deeper than the depth of the second groove 142. The wider first groove 141 is relatively deeper, allowing lithium ions to pass through the negative electrode active material layer 122 relatively easily and be deintercalated in the active material layer inside the negative electrode sheet 120.

[0099] The second groove 142 is narrow in width and shallow in depth. If only the second groove 142 is present, the resistance to lithium ion insertion and extraction in the negative electrode active material layer 122 during charge and discharge is still relatively large. The electron migration speed is faster than the lithium ion migration speed, and lithium ions accumulate on the surface of the negative electrode sheet 120, resulting in an increase in the internal resistance of the battery and a decrease in the battery charge and discharge performance.

[0100] Therefore, the combination of the first groove 141 and the second groove 142 can provide sufficient and deep channels for lithium ions to enter the inner negative electrode active material layer 122 while meeting the requirements of battery safety and capacity, thereby improving battery performance.

[0101] In some optional embodiments, the extending direction of the groove group 140 is parallel to the extending direction of the negative electrode sheet 120; or,

[0102] An angle is formed between the extending direction of the groove group 140 and the extending direction of the negative electrode sheet 120 .

[0103] It should be noted that the extension direction of the negative electrode sheet 120 here is the length direction of the negative electrode sheet 120 , that is, the extension direction of the groove group 140 is the length direction of the groove group 140 , wherein the extension direction of the groove group 140 is the same as the length direction of the negative electrode sheet 120 .

[0104] It should be noted that the extension direction of the groove group 140 is consistent with the negative electrode sheet 120, which reduces the path resistance of ion transmission, improves the conductivity of the battery, and reduces the difficulty and cost of implementation; the existence of the angle can increase the diffusion path length of lithium ions in the negative electrode active material layer 122, helps to improve the diffusion uniformity of lithium ions, reduce the excessive concentration of ions in a certain direction, and thus improve the overall performance of the battery.

[0105] The extending direction of the groove set 140 here refers to the extending direction of the first groove 141 and the second groove 142 .

[0106] It should be noted that because the direction of the groove group 140 is not completely consistent with the direction of the negative electrode sheet 120, the current distribution is more uniform. This can reduce the problem of excessive local current density, reduce the risk of overheating and local excessive reaction, and improve the safety and stability of the battery.

[0107] In some embodiments, the groove set 140 is aligned with the negative electrode sheet 120 to better maintain the mechanical integrity of the negative electrode sheet 120. This can reduce structural weaknesses introduced by the grooves, thereby improving the overall mechanical strength and durability of the battery.

[0108] In summary, this design can improve the battery's charge and discharge efficiency and cycle life, and enhance the battery's performance at high-rate discharge.

[0109] Figure 4 This is a schematic diagram of the structure of the groove group in the battery cell provided in the embodiment of the present application. Figure 3 and Figure 4 As shown, in some optional embodiments, the angle A between the extension direction of the groove group 140 and the extension direction of the negative electrode sheet 120 satisfies: A≤15°.

[0110] It should be noted that the extending direction of the groove group 140 here is the length direction of the groove group 140 , that is, there is an angle A between the length direction of the groove group 140 and the length direction of the negative electrode sheet 120 .

[0111] It should be noted that an angle of less than or equal to 15 degrees allows lithium ions to have slightly different paths in the negative electrode active material layer 122, which increases the diffusion path of the ions to a certain extent and improves the uniform distribution of the ions without significantly weakening the structural integrity of the negative electrode sheet 120.

[0112] The small angle design maintains a roughly consistent current flow direction while slightly adjusting the current path, resulting in more uniform current distribution. This helps reduce local hot spots and excessive current density, improving battery safety and lifespan.

[0113] In addition, by setting an angle less than or equal to 15 degrees, the wire groove has only some points on the edge of the length direction of the pole piece, rather than the entire line, so that in the subsequent cutting process, the cutter will not cut the entire wire groove, thereby avoiding the problem of edge powder falling due to insufficient stress in the wire groove when the wire groove covers the edge during the cutting process.

[0114] By optimizing the ion transport path and current distribution, the battery's charge and discharge efficiency and cycle life are improved. The small angle design improves the overall performance of the battery without significantly increasing manufacturing complexity.

[0115] In addition, the groove group 140 is not completely continuous in the extension direction of the negative electrode sheet 120 , which can ensure the uniformity of lithium ion insertion into the negative electrode active material layer 122 while further reducing the loss of active materials in the negative electrode active material layer 122 .

[0116] Figure 5 This is a cross-sectional view of the front side of a negative electrode sheet in a battery cell provided in an embodiment of the present application. Figure 6 This is a cross-sectional view of the back of a negative electrode sheet in a battery cell provided in an embodiment of the present application. Figure 7 This is a cross-sectional view of the negative electrode sheet in the second battery cell provided in an embodiment of the present application.

[0117] like Figures 5 to 7 As shown, in some optional embodiments, the width W1 of the first groove 141 satisfies: W1 ≥ 5 μm; and / or,

[0118] The width W2 of the second groove 142 satisfies: 0.1 μm≤W2≤5 μm; and / or,

[0119] The difference between the width W1 of the first groove 141 and the width W2 of the second groove 142 satisfies: 0.1 μm≤W1-W2≤30 μm.

[0120] It should be noted that the larger width allows more lithium ions to pass through, thereby improving ion transport efficiency. This helps achieve faster reactions during the charge and discharge process. The narrower second groove 142 provides a fine ion channel, which helps achieve more uniform ion distribution and reduce local overreaction.

[0121] The wider first groove 141 helps to reduce the internal resistance of the battery and improve the power density and overall efficiency of the battery.

[0122] In addition, the narrower second groove 142 reduces excessive removal of the negative electrode active material, maintaining the integrity of the material and the capacity of the battery.

[0123] The first groove 141 should be wide enough to allow a large area of ​​lithium ions to be embedded into the inner active material. In contrast, the second groove 142 needs to be less than a certain width, otherwise the second electrode active material will still lose too much.

[0124] The width difference between the first groove 141 and the second groove 142 can achieve an optimal balance between ion transmission efficiency and negative electrode material integrity. When W1-W2 falls within the above range, the first groove 141 and the second groove 142 on the electrode surface can fully play their respective roles, providing lithium ions with sufficient and deep channels to penetrate into the inner active material layer.

[0125] Table 1: W1-W2 and battery performance of various examples and comparative examples

[0126]

[0127] It should be noted that ES-Rct represents the difficulty for lithium ions to enter the negative electrode sheet 120 and combine with the negative electrode active material. A larger value indicates a greater difficulty.

[0128] The 600T cycle capacity retention rate represents the capacity decay of the battery after repeated cycles, with larger values ​​indicating less decay. The 600T cycle expansion rate represents the volume expansion of the battery after repeated cycles. Larger volume expansion can easily rupture the membrane shell, leading to leakage and other safety hazards. Therefore, smaller values ​​indicate a safer battery after long-term use.

[0129] Therefore, as shown in Table 1, in Examples 1-0 to 1-3, the ES-Rct values ​​are small, which indicates that it is relatively easy for lithium ions to enter the interior of the negative electrode sheet 120 and combine with the negative electrode active material, the 600T cycle capacity retention rate is good, and the 600T cycle expansion value is small, indicating that the battery safety is high, and all of them are slightly lithium-deposited.

[0130] In contrast, in comparative examples 1-4, the width of the first groove 141 is too large, or no groove is provided on the negative electrode sheet 120 of comparative example 1-5, and the ES-Rct value is large, which indicates that it is difficult for lithium ions to enter the interior of the negative electrode sheet 120 and combine with the negative electrode active material. The 600T cycle capacity retention rate is poor, and the 600T cycle expansion value is large, indicating that the battery safety is poor and lithium plating is serious.

[0131] Figure 8 A schematic diagram of the partial structure of the groove group in the battery cell provided in an embodiment of the present application.

[0132] like Figure 8 As shown, in some optional embodiments, the depth H1 of the first groove 141 satisfies: 4 μm≤H1≤20 μm.

[0133] In some optional embodiments, the depth H2 of the second groove 142 satisfies: 0.1 μm≤H2≤4 μm.

[0134] In some optional embodiments, the difference between the depth H1 of the first groove 141 and the depth H2 of the second groove 142 satisfies: 0.1 μm≤H1-H2≤20 μm.

[0135] It should be noted that the deeper first grooves 141 allow lithium ions to penetrate deeper into the negative electrode active material layer 122, thereby improving ion transport efficiency. The shallower second grooves 142 provide fine ion channels, enabling more uniform ion distribution and reducing local overreaction.

[0136] The greater depth of the deeper first groove 141 provides a larger surface area, which helps to improve the capacity and charge and discharge rate of the battery.

[0137] The shallower second groove 142 design reduces excessive removal of the negative electrode active material, thereby maintaining the structural integrity of the material and the capacity of the battery.

[0138] Specifically, to ensure that lithium ions can penetrate into the inner active material through the first groove 141 and be deintercalated, the first groove 141 needs to have a certain depth. At the same time, to ensure that the loss of active material in the negative electrode sheet 120 is not too large, the depth of the second groove 142 needs to be subject to certain restrictions.

[0139] Table 2: H1 and H2 and battery performance of various examples and comparative examples

[0140]

[0141] As shown in Table 2, Examples 2-0 to 2-2 meet the design ranges of H1 and H2, and have small ES-Rct values, indicating that lithium ions have low difficulty in entering the negative electrode sheet 120 and combining with the negative electrode active material. The 600T cycle capacity retention rate is good, and the 600T cycle expansion value is small, indicating that the battery is relatively safe, and all of them have slight lithium plating.

[0142] In Comparative Examples 2-3 and 2-4, the ES-Rct values ​​are large, which indicates that it is difficult for lithium ions to enter the negative electrode sheet 120 and combine with the negative electrode active material. The 600T cycle capacity retention rate is poor, and the 600T cycle expansion value is large, indicating that the battery safety is poor and lithium plating is serious.

[0143] like Figure 5 and Figure 6 As shown, in some optional embodiments, within a unit area, the number L1 of the first grooves 141 and the sheet width H3 of the negative electrode sheet 120 satisfy: L1 / H3 mm ≥ 1 / 3 (mm -1 ).

[0144] It should be noted that there is at least one first groove 141 every 3 mm of the negative electrode sheet 120 extending in the width direction of the sheet.

[0145] In some optional embodiments, within a unit area, the number L2 of the second grooves 142 and the width H3 of the negative electrode sheet 120 satisfy the following relationship: L2 / H3mm≥10 / 3(mm -1 ).

[0146] It should be noted that there are at least 10 second grooves 142 for every 3 mm of extension in the width direction of the negative electrode sheet 120 .

[0147] The sheet material here refers to the electrode sheet, which is a distinct rectangle. The width refers to the wide side of the rectangle. Explained through the electrode tab, the width edge can be understood as the location of the tab. It should be noted that a sufficient number of first grooves 141 are ensured across the width of the negative electrode sheet 120 to provide effective channels for rapid lithium ion transport. A high density of second grooves 142 ensures sufficient channels across the negative electrode sheet 120 for uniform ion distribution.

[0148] It should be noted that the reasons for the analysis are as follows: the first groove 141 with a relatively wide width is relatively deep, so that lithium ions can pass through it relatively easily through the negative electrode active material layer 122 and be deintercalated in the inner active material of the negative electrode sheet 120. However, precisely because the first groove 141 is wide and deep, the dense distribution will lead to excessive loss of active materials in the negative electrode sheet 120, and the loose distribution will make many lithium ions far away from the first groove 141 unable to pass through the first groove 141 into the inner active material for deintercalation, resulting in poor reaction uniformity.

[0149] The densely distributed second grooves 142 provide new channels for lithium ions to enter the inner layer of active material, improving the uniformity of lithium ion intercalation and deintercalation from the active material of the negative electrode sheet 120. Moreover, since the second grooves 142 are narrow, even if densely distributed, there will not be excessive loss of active material. However, the width of the second grooves 142 is narrow and the depth is shallow. When there are only the second grooves 142, the resistance to lithium ion intercalation and deintercalation in the active material of the negative electrode sheet 120 during charging and discharging is still large. The electron migration speed is faster than the lithium ion migration speed, and the lithium ions accumulate on the surface of the negative electrode sheet 120, resulting in an increase in the internal resistance of the battery and a decrease in the battery charging and discharging performance.

[0150] Continue to refer Figures 5 to 7 In some optional embodiments, along the width direction of the negative electrode sheet 120 , a distance W3 between the first groove 141 and the second groove 142 satisfies: 2 μm≤W3≤80 μm.

[0151] The extending direction of the first groove 141 and the extending direction of the second groove 142 are the length direction of the negative electrode sheet 120 , and the extending direction of the first groove 141 and the extending direction of the second groove 142 are the same.

[0152] Among them, when the extension direction of the first groove 141 and the extension direction of the second groove 142 have an angle with the length direction of the negative electrode sheet 120, the first groove 141 and the second groove 142 at this time can be understood as oblique grooves, wherein the oblique grooves are separated by the distance between the first groove 141 and the second groove 142 in the width direction of the negative electrode sheet 120, and the spacing takes the maximum value of this distance.

[0153] In some optional embodiments, along the width direction of the negative electrode sheet 120 , a difference between a distance between a first groove 141 and an adjacent second groove 142 and a distance between a first groove 141 and an adjacent first groove 141 is less than 10 μm.

[0154] In some optional embodiments, along the width direction of the negative electrode sheet 120 , a difference between a distance between a second groove 142 and an adjacent first groove 141 and a distance between a second groove 142 and an adjacent second groove 142 is less than 10 μm.

[0155] That is to say, in the above embodiment, along the width direction of the negative electrode sheet 120, the distance between the first groove 141 and the adjacent second groove 142, the distance between the first groove 141 and the adjacent first groove 141, the distance between the second groove 142 and the adjacent first groove 141, and the distance between the second groove 142 and the adjacent second groove 142 are similar, thereby further improving the uniformity of the wire groove.

[0156] It should be noted that reasonable groove spacing ensures that lithium ions have sufficient transmission paths in the negative electrode active material layer 122, which helps to optimize ion transmission efficiency and reduce ion transmission resistance.

[0157] It should be noted that the analysis reasons are as follows: in order to ensure that lithium ions in a large area have channels to enter the inner layer active material, in addition to the sufficient number of groove groups 140, the distribution between the first groove 141 and the second groove 142 also needs to be uniform to a certain extent, that is, the distance between the first groove 141 and the second groove 142 should not be too large.

[0158] The center-to-center distance between adjacent first grooves 141 and second grooves 142 is defined as the distance W3 between the first grooves 141 and second grooves 142. When the first grooves 141 and second grooves 142 are parallel, a perpendicular line drawn from a point on the center axis of the first groove 141 to the center axis of the adjacent second groove 142 must meet the following criteria.

[0159] Table 3: W3 and battery performance of various examples and comparative examples

[0160]

[0161] As shown in Table 3, W3 in Examples 3-0 to 3-2 is between 2 μm and 80 μm, which helps to optimize the ion transmission efficiency and reduce the resistance to ion transmission. It is less difficult for lithium ions to enter the negative electrode sheet 120 and combine with the negative electrode active material. The 600T cycle capacity retention rate is good and the 600T cycle expansion value is small, indicating that the battery safety is high and all of them have slight lithium plating.

[0162] In some optional embodiments, the negative electrode sheet 120 includes an active layer and a hollow foil area 125 , and the active layer is provided with a groove group 140 .

[0163] The active layer may include a double-sided area 123 and a single-sided area 124 .

[0164] At least one of the double-sided area 123 and the single-sided area 124 is provided with a groove set 140 .

[0165] It should be noted that such a configuration can provide a sufficiently large area of ​​channels for lithium ions to be intercalated and deintercalated into the negative electrode active material layer 122 in the negative electrode sheet 120 .

[0166] It should be noted that the double-sided area 123 refers to the area where the paste is applied on both the front and back sides of the negative electrode sheet 120, that is, the negative electrode active material layer 122 is applied on both the front and back sides of the negative electrode current collector 121. The single-sided area 124 refers to the area where the paste is applied on the front side but not on the back side, that is, the negative electrode active material layer 122 is applied on the front side but not on the back side of the negative electrode current collector 121. The blank foil area 125 refers to the area where the paste is not applied on both the front and back sides.

[0167] The reasons for the analysis are as follows: In order to provide a sufficiently large area for lithium ions to have a channel for deintercalation with the active material in the inner layer of the second electrode sheet, the groove group 140 does not avoid the single-sided area 124. Therefore, the lithium ions on the surface of the positive electrode sheet 110 opposite to the single-sided area 124 have a corresponding channel to enter the inner layer of the negative electrode sheet 120.

[0168] If groove groups 140 are formed at the interface between the negative electrode active material layer 122 and the negative electrode current collector 121, the interface will become more fragile, and the expansion stress generated during battery cycling will greatly increase the risk of fracture. In addition, if groove groups 140 are formed on the surface of the negative electrode current collector 121 (foil), peeled dust may still adhere to the foil surface and fall off from the surface after the battery is manufactured, piercing the separator 130 and causing a battery short circuit. Therefore, to reduce the risk of electrode breakage during cycling and internal battery short circuits, the groove groups 140 must be located away from the empty foil area 125.

[0169] In some optional embodiments, there is a boundary end between the empty foil area 125 and the active layer, that is, there is a boundary end between the empty foil area 125 and the single-sided area 124;

[0170] When on the front side of the negative electrode sheet 120 , the distance W4 between the end of the groove group 140 and the junction end satisfies: 0.5 mm ≤ W4 ≤ 6 mm; and / or,

[0171] When on the back side of the negative electrode sheet 120 , the distance W5 between the end of the groove group 140 and the boundary end satisfies: 0.5 mm≤W5≤6 mm.

[0172] It should be noted that the above-mentioned setting can reduce the risk of electrode cycle breakage and internal short circuit of the battery.

[0173] In addition, by setting an appropriate distance between W4 and W5 , the electrochemical reaction interference between the end and the boundary end of the groove group 140 is reduced, thereby ensuring the functional independence of each area.

[0174] In some optional embodiments, when the battery cell 100 is a wound core, along the length direction of the negative electrode sheet 120 , the distance W6 between the head end of the groove group 140 and the head end of the negative electrode sheet 120 satisfies: 0.5 mm ≤ W6 ≤ 6 mm.

[0175] It should be noted that, in the actual production process, the plurality of negative electrode sheets 120 are continuous with each other. To prevent the foil of the previous negative electrode sheet 120 from being scratched, it is necessary to limit the distance between the head end of the groove group 140 and the head end of the negative electrode sheet 120 .

[0176] It should be noted that if the distance W6 between the head end of the groove group 140 and the head end of the negative electrode sheet 120 is greater than 6 mm, it means that the setting area of ​​the first groove 141 and the second groove 142 in the groove group 140 is reduced, thereby reducing the channel for lithium ions to enter the inner active material layer.

[0177] In some optional embodiments, the width of the negative electrode sheet 120 is greater than the width of the positive electrode sheet 110;

[0178] A distance W7 between the notch of the groove group 140 located at the top of the negative electrode sheet 120 and the top edge of the negative electrode sheet 120 satisfies: 0.5 mm≤W7≤5 mm.

[0179] It should be noted that in order to prevent lithium ion deposition due to lack of an intercalation layer during charge and discharge, the width of the negative electrode sheet 120 must be greater than that of the positive electrode sheet 110 during battery design.

[0180] It should be noted that the groove group 140 should completely cover the positive electrode sheet 110 along the length of the negative electrode sheet 120, with the head extending at least 3 mm beyond the head of the positive electrode sheet 110 and the tail extending at least 3 mm beyond the tail of the positive electrode sheet 110. This advantage ensures that lithium ions can be deintercalated and deintercalated within the negative electrode active material layer 122 through the groove group 140 during charging and discharging. Furthermore, the groove group 140 in the area not covered by the positive electrode sheet 110 can guide the electrolyte to the area covered by the positive electrode sheet 110 through capillary action, which helps to improve the electrolyte retention of the battery cell 100.

[0181] The groove group 140 can completely cover the positive electrode sheet 110 in the width direction of the negative electrode sheet 120 and can also be completely covered by the positive electrode sheet 110. It is preferred to ensure that the distance between the groove group 140 and the edge of the negative electrode sheet 120 in the width direction of the negative electrode sheet 120 meets W7 (to ensure that the edge of the electrode sheet is not cut). In addition, when the groove group 140 is produced, the negative electrode active material layer 122 on the surface needs to be peeled off and it cannot be completely cleaned. Therefore, there are some residues on the surface of the negative electrode sheet 120 in the area beyond the positive electrode sheet 110. Once this residue, that is, the uncleaned active material, falls off in the final finished battery, it is possible to directly contact the active material on the surface of the positive electrode sheet 110, causing a micro-short circuit, so that the battery will still discharge rapidly when not in use, which impairs the battery performance. Therefore, in order to avoid this situation, the top of the top groove group 140 is between 0.5mm and 5mm from the top of the second electrode sheet.

[0182] Table 4: W4 and battery performance of various embodiments and comparative examples

[0183]

[0184] As shown in Table 4, when the distance W4 between the end and the junction of the groove group 140 is between 0.5 mm and 6 mm, the electrochemical reaction interference between the end and the junction of the groove group 140 is reduced, the functional independence of each area is ensured, the difficulty for lithium ions to enter the negative electrode sheet 120 and combine with the negative electrode active material is relatively low, the 600T cycle capacity retention rate is good, and the 600T cycle expansion value is small, indicating that the battery is relatively safe and lithium plating is slight.

[0185] The battery cell provided in the embodiment of the present application includes a positive electrode sheet, including a positive electrode current collector and a positive electrode active material layer respectively arranged on at least one side of the positive electrode current collector; a negative electrode sheet, including a negative electrode current collector and a negative electrode active material layer arranged on opposite sides of the negative electrode current collector; a separator, and the separator is located between adjacent positive electrode sheets and negative electrode sheets; at least one groove group is provided on the side of the negative electrode active material layer facing away from the negative electrode current collector, and the groove group includes a first groove and a second groove, the width of the first groove is greater than the width of the second groove, and the depth of the first groove is greater than the depth of the second groove.

[0186] By opening two grooves of different depths and widths on the negative electrode active material layer, it is helpful to achieve a more balanced electrochemical reaction rate in the negative electrode active material layer. Under the premise of meeting the safety and capacity of the battery, lithium ions can have sufficient and deep enough channels to enter the negative electrode active material layer, which can improve the utilization rate of the active material, ensure a more uniform distribution of lithium ions, increase the capacity and energy density of the battery, and thus improve the cycle stability of the battery.

[0187] In addition, an embodiment of the present application further provides a battery, including a battery cell 100 .

[0188] The specific structure, working principle and function of the battery cell 100 have been described in detail in the aforementioned embodiments and will not be repeated here.

[0189] The battery provided in the embodiment of the present application, by providing two grooves of different depths and widths on the negative electrode active material layer, helps to achieve a more balanced electrochemical reaction rate in the negative electrode active material layer. It can provide lithium ions with sufficient and deep channels to enter the negative electrode active material layer while meeting the battery safety and capacity requirements, thereby improving the utilization rate of the active material, ensuring a more uniform distribution of lithium ions, and increasing the capacity and energy density of the battery, thereby improving the cycle stability of the battery.

[0190] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above 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 invention.

Claims

1. A battery cell (100), characterized in that: include: A positive electrode sheet (110) comprising a positive electrode current collector (111) and a positive electrode active material layer (112) respectively arranged on at least one side of the positive electrode current collector (111); A negative electrode sheet (120) comprising a negative electrode current collector (121) and negative electrode active material layers (122) disposed on opposite sides of the negative electrode current collector (121); a separator (130), the separator (130) being located between the adjacent positive electrode sheet (110) and the adjacent negative electrode sheet (120); At least one groove group (140) is provided on the side of the negative electrode active material layer (122) facing away from the negative electrode current collector (121), and the groove group (140) comprises at least a first groove (141) and a second groove (142); The width of the first groove (141) is greater than the width of the second groove (142), and / or the depth of the first groove (141) is greater than the depth of the second groove (142); The first groove (141) and the second groove (142) are both plural; within a unit area, the number of the first grooves (141) is smaller than the number of the second grooves (142).

2. The battery cell (100) according to claim 1, characterized in that The extending direction of the groove group (140) is parallel to the extending direction of the negative electrode sheet (120); or, An included angle A is formed between the extending direction of the groove group (140) and the extending direction of the negative electrode sheet (120), satisfying the following condition: A≤15°.

3. The battery cell (100) according to claim 1 or 2, characterized in that: The width W1 of the first groove (141) satisfies: W1 ≥ 5 μm; and / or, The width W2 of the second groove (142) satisfies: 0.1 μm≤W2≤5 μm; and / or, The difference between the width W1 of the first groove (141) and the width W2 of the second groove (142) satisfies: 0.1 μm≤W1-W2≤30 μm.

4. The battery cell (100) according to claim 1 or 2, characterized in that: The depth H1 of the first groove (141) satisfies: 4 μm ≤ H1 ≤ 20 μm; and / or, The depth H2 of the second groove (142) satisfies: 0.1 μm≤H2≤4 μm; and / or, The difference between the depth H1 of the first groove (141) and the depth H2 of the second groove (142) satisfies: 0.1 μm≤H1-H2≤20 μm.

5. The battery cell (100) according to claim 4, characterized in that: Within a unit area, the number L1 of the first grooves (141) and the sheet width H3 of the negative electrode sheet (120) satisfy the following: L1 / H3mm≥1 / 3(mm -1 ); and / or, Within a unit area, the number L2 of the second grooves (142) and the sheet width H3 of the negative electrode sheet (120) satisfy the following relationship: L2 / H3mm≥10 / 3(mm -1 ).

6. The battery cell (100) according to claim 1 or 2, characterized in that: Along the width direction of the negative electrode sheet (120), the distance W3 between the first groove (141) and the second groove (142) satisfies: 2 μm≤W3≤80 μm; and / or, Along the width direction of the negative electrode sheet (120), the difference between the distance between the first groove (141) and the adjacent second groove (142) and the distance between the first groove (141) and the adjacent first groove (141) is less than 10 μm; and / or, Along the width direction of the negative electrode sheet (120), the difference between the distance between the second groove (142) and the adjacent first groove (141) and the distance between the second groove (142) and the adjacent second groove (142) is less than 10 μm.

7. The battery cell (100) according to claim 1 or 2, characterized in that: The negative electrode sheet (120) includes an active layer and a hollow foil area (125); The active layer is provided with the groove group (140); a boundary end is provided between the empty foil area (125) and the active layer; On the front side of the negative electrode sheet (120), the distance W4 between the end of the groove group (140) and the junction end satisfies: 0.5 mm ≤ W4 ≤ 6 mm; and / or, When on the back side of the negative electrode sheet (120), the distance W5 between the end of the groove group (140) and the junction end satisfies: 0.5 mm ≤ W5 ≤ 6 mm.

8. The battery cell (100) according to claim 1 or 2, characterized in that: When the battery cell (100) is a winding core, along the length direction of the negative electrode sheet (120), a distance W6 between the head end of the groove group (140) and the head end of the negative electrode sheet (120) satisfies the following relationship: 0.5 mm ≤ W6 ≤ 6 mm.

9. The battery cell (100) according to claim 1 or 2, characterized in that: The width of the negative electrode sheet (120) is greater than the width of the positive electrode sheet (110); In the width direction, a distance W7 between the notch of the groove group (140) located at the top of the negative electrode sheet (120) and the top edge of the negative electrode sheet (120) satisfies the following: 0.5 mm ≤ W7 ≤ 5 mm.

10. A battery, characterized in that: Comprising the battery cell (100) according to any one of claims 1 to 9.

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