Battery cell and battery

Abstract

This invention relates to the field of secondary battery technology and discloses a battery cell and a battery. The battery cell includes a straight section and a corner section, and includes electrodes and a separator. The battery cell is formed by winding two electrodes and a separator. The electrodes include a current collector and an active material layer. The thickness of the active material layer on a single electrode is M mm. Multiple protrusions are formed on one side surface of the electrode, and at least part of the multiple protrusions are located in the corner section. The area of ​​the protrusions in the corner section is K times the area of ​​the electrode in the corner section. The average spacing between two adjacent layers of electrodes of the same polarity in the corner section is L mm, satisfying 11.0*10 ‑2 ≤K / (M*L)≤2307.7*10 ‑2 The above technical solution can both ensure that the protrusions effectively compensate for the gaps and prevent lithium plating, and also ensure the energy density of the battery.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, specifically to battery cells and batteries. Background Technology

[0002] Currently, wound-type battery cells are widely used in battery products. A battery cell is generally formed by winding electrodes and a separator, and has straight sections and corner sections. The electrode surface is coated with an active material layer to enable the battery's charging and discharging functions. As the battery industry's requirements for energy density continue to increase, the corner sections of the battery cell consistently suffer from poor ion transport efficiency, leading to lithium plating. This results in decreased battery capacity and an increased risk of short circuits, seriously affecting battery safety. Summary of the Invention

[0003] This invention provides a battery cell and a battery to solve the problem of lithium plating caused by poor ion transport efficiency in the corner section of the battery cell.

[0004] In a first aspect, the present invention provides a battery cell comprising a straight section and a corner section. The battery cell includes electrode sheets and a separator disposed between two adjacent electrode sheets. The battery cell is formed by winding two electrode sheets and the separator. Each electrode sheet includes a current collector and an active material layer disposed on at least one surface of the current collector. The thickness of the active material layer on a single electrode sheet is M mm. A plurality of protrusions are formed on one surface of the electrode sheet. At least a portion of the plurality of protrusions is located in the corner section. The area of ​​the protrusions located in the corner section is K times the area of ​​the electrode sheet located in the corner section. The average spacing between two adjacent layers of electrode sheets of the same polarity located in the corner section is L mm, satisfying 11.0*10. -2 ≤K / (M*L)≤2307.7*10 -2 .

[0005] Beneficial effects: By setting protrusions at least partially located in the corner sections on the electrode surface, these protrusions compensate for the gaps between adjacent electrodes in the corner section, effectively reducing the electrode gaps, shortening the ion transport distance in the corner section, improving ion transport efficiency, and thus reducing lithium plating at the corner section. Simultaneously, by comprehensively controlling the area ratio K of the protrusions in the corner section, the thickness ratio M of the active material layer in the electrode, and the average spacing L of the electrode corner section, it is achieved that the ratio meets 11.0*10. -2 ≤K / (M*L)≤2307.7*10 -2 This design ensures that the protrusions can compensate for the gaps and prevent lithium plating, while also taking into account the content of active materials in the electrode and the number of electrode layers, effectively guaranteeing the energy density of the battery and improving the safety of the cell and the energy density of the battery.

[0006] In a second aspect, the present invention also provides a battery comprising: the battery cell described in the first aspect. Attached Figure Description

[0007] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0008] Figure 1 This is a perspective view of a battery according to an embodiment of the present invention; Figure 2 This is an exploded view of the battery according to an embodiment of the present invention; Figure 3 This is a cross-sectional view of the battery cell according to an embodiment of the present invention; Figure 4 This is a cross-sectional view of the electrode sheet according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the electrode sheet in its unfolded state according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the bottom surface of the battery cell according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the cross-section of the battery cell according to an embodiment of the present invention; Figure 8 An X-ray non-destructive scanning image of the corner segment of the battery cell in an embodiment of the present invention.

[0009] Explanation of reference numerals in the attached figures: 100-battery; 10-Cell; 10a-Straight section; 10b-Corner section; 11-Electrode; 111-First electrode; 112-Second electrode; 113-Separator; 11a-Current collector; 11b-Active material layer; 11c-Protrusion; 11d-Recess; 11f-Winding start end; 11e-Winding end; 11g-Arrangement of protrusions; 12-Taper; 20-Shell; 21-Shell body; 22-Cover; 30 - Electrode terminal; X - Length direction; Y - Width direction; Z - Height direction. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] It has been observed that the straight sections of battery cells are typically processed using a hot-pressing process. This process tends to stretch the electrodes towards the corners, increasing the gap between adjacent electrode layers at these corners. This increases the transport distance of ions at the corners, reduces transport efficiency, and makes lithium plating more likely. Lithium plating not only causes battery capacity decay, but the resulting lithium dendrites can also puncture the separator, causing short circuits and negatively impacting battery safety. Furthermore, increasing the content of active materials in the electrodes to improve battery energy density further exacerbates the lithium plating problem at the corners.

[0012] To address the issues of low ion transport efficiency and easy lithium plating at the corners of battery cells, while ensuring battery energy density, this invention provides protrusions, at least partially located at the corners, on the electrode surface. These protrusions compensate for the gaps between adjacent electrodes at the corners, effectively reducing the electrode gaps, shortening the ion transport distance at the corners, and improving ion transport efficiency, thereby reducing lithium plating at the corners. Furthermore, by comprehensively controlling the area ratio of the protrusions in the corners, the thickness ratio of the active material layer in the electrodes, and the average spacing of the electrodes at the corners, this invention ensures the effective gap compensation of the protrusions, preventing lithium plating, while also considering the content of active material and the number of electrode layers, effectively guaranteeing battery energy density and improving both cell safety and battery energy density.

[0013] The battery cell of this application embodiment can be used in various types of batteries, including secondary batteries such as lithium-ion batteries and sodium-ion batteries. The battery cell can be assembled alone or in combination into a battery casing to form a battery cell. Batteries containing the battery cell of this application embodiment can be used in various electrical devices, such as mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc.

[0014] The following is combined Figures 1 to 8 The embodiments of the present invention will be described in detail below.

[0015] According to an embodiment of the present invention, a battery cell 10 is provided. The battery cell 10 includes a straight section 10a and a corner section 10b. The battery cell 10 includes an electrode 11 and a separator 113 disposed between two adjacent electrode 11s. The battery cell 10 is formed by winding two electrode 11s and a separator 113. The electrode 11 includes a current collector 11a and an active material layer 11b disposed on at least one side surface of the current collector 11a. The thickness of the active material layer 11b on a single electrode 11 is M mm. A plurality of protrusions 11c are formed on one side surface of the electrode 11. The plurality of protrusions 11c are at least partially located in the corner section 10b. The ratio of the area of ​​the protrusions 11c located in the corner section 10b to the area of ​​the electrode 11 located in the corner section 10b is K. The average spacing between two adjacent layers of electrode 11 of the same polarity located in the corner section 10b is L mm, satisfying 11.0*10. -2 ≤K / (M*L)≤2307.7*10 -2 .

[0016] In this embodiment of the application, for ease of explanation, X represents the length direction X of the battery 100, Y represents the width direction Y of the battery 100, and Z represents the height direction Z of the battery 100.

[0017] A battery cell is the component in a battery 100 where electrochemical reactions occur; it is the smallest unit in a battery capable of carrying out electrochemical reactions such as charging / discharging.

[0018] Cell 10 is the basic unit in a battery, typically comprising a positive electrode, a negative electrode, and a separator. Lithium-ion cells 10 primarily function by the intercalation and deintercalation of lithium ions between the positive and negative electrodes. In a cuboid cell 10, thin-film structures are wound or stacked into an electrode assembly with a roughly cuboid shape.

[0019] A wound cell 10 is generally a cell made by winding a continuous positive electrode, a negative electrode, and a separator. The separator is located between adjacent positive and negative electrode sheets.

[0020] In this embodiment, the battery cell 10 is a wound battery cell 10, which is made by a winding process from continuous electrode sheets 11 and separator 113. The separator 113 is located between adjacent electrode sheets of different polarities 11. After being wound and formed, it is formed by a pressing process to form a structure with a straight section 10a and a corner section 10b. The battery cell 10 can be assembled individually or in multiple stacks into the casing 20 of the battery 100 to form a single battery cell 100.

[0021] The straight section 10a is a linear structural region formed after the battery cell 10 is wound and pressed together. It is the main body of the battery cell 10. The electrode 11 in this linear structural region is in a straight and extended state without bending. After the straight section 10a of the battery cell 10 is processed by hot pressing, the adjacent electrode 11 layers are tightly bonded together, which can improve the structural compactness and energy density of the battery cell 10.

[0022] The corner section 10b is a bent transition area formed after the battery cell 10 is wound and pressed. It is an arc-shaped connection between two straight sections 10a. It is formed by bending the electrode 11 and the separator 113 during the winding process. The electrode 11 in the corner section 10b is under stress due to bending, which is an area in the battery cell 10 where the gap between adjacent electrode 11 layers is prone to increase.

[0023] The electrode 11 is the core functional component in the cell 10 that realizes the electrochemical reaction. It is divided into positive electrode 11 and negative electrode 11, which are alternately arranged on both sides of the separator 113 and jointly participate in the ion insertion and extraction reaction during the charging and discharging process of the battery 100.

[0024] The positive current collector serves as a substrate and is mainly used to attach the positive active material, thereby collecting the current generated by the positive active material and outputting the current to the outside.

[0025] The positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0026] The negative electrode current collector serves to collect current and acts as a carrier for the negative electrode slurry. The negative electrode slurry (negative electrode active material, conductive agent, binder, etc.) is coated onto the negative electrode current collector. The negative electrode current collector collects electrons from the negative electrode active material and conducts them to the external circuit, realizing the process of converting chemical energy into electrical energy.

[0027] The negative electrode current collector can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium, and can be surface-plated with silver. Composite current collectors may include a polymer substrate and a metal layer. Composite current collectors can be formed by depositing metal materials (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) onto a polymer substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0028] The active material layer 11b is a functional layer coated on the surface of the current collector 11a. It is made by mixing active materials, conductive agents, binders, and other raw materials in a certain proportion to form a slurry, which is then coated on the surface of the current collector 11a and formed by drying and rolling. It is the core part of the battery cell 10 for energy storage. The active material layer 11b of the positive electrode 11 can be made of positive electrode active materials such as lithium phosphate, lithium transition metal oxides, and their modified compounds, combined with conductive agents such as graphite, carbon black, and carbon nanotubes, and binders such as polyvinylidene fluoride and styrene-butadiene rubber. The active material layer 11b of the negative electrode 11 can be made of negative electrode active materials such as graphite, hard carbon, and silicon-carbon composites, combined with conductive agents such as conductive carbon black and carbon nanotubes, and binders such as styrene-butadiene rubber and polyacrylic acid. The active material layer 11b can be coated only on one side of the current collector 11a, or it can be coated on both sides of the current collector 11a.

[0029] Specifically, the positive electrode 11 is one of the core components in the battery 100 that carries the positive electrode active material. During charging, metal ions (e.g., lithium ions) are extracted from the crystal lattice of the positive electrode active material (oxidation reaction), migrate through the electrolyte, and embed into the negative electrode. During discharging, metal ions (e.g., lithium ions in the lithium battery 100) are extracted from the negative electrode and embed into the crystal lattice of the positive electrode active material (reduction reaction), thus realizing the storage and release of lithium ions.

[0030] A positive electrode generally includes a positive current collector and a positive active material layer. The positive active material layer is coated on at least one surface of the positive current collector and includes: a positive active material, a conductive agent, and a binder. The positive active material includes, but is not limited to, at least one of the following: lithium phosphates, lithium transition metal oxides and their respective modified compounds, or other conventional materials that can be used as positive electrode active materials in batteries. These positive active materials can be used alone or in combination. Lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0031] The positive electrode conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene and carbon nanofibers.

[0032] The positive electrode binder includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0033] During the charging process of the battery 100, active ions (such as Li ions) from the positive electrode are embedded in the negative electrode, while electrons from the positive electrode are transferred to the negative electrode through the external circuit to maintain charge balance. During the discharging process, the active ions (such as Li ions) previously embedded in the negative electrode can be released, while electrons from the negative electrode are transferred to the negative electrode through the external circuit to maintain charge balance, thus achieving energy storage and release.

[0034] Materials / Composition: The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The negative electrode active layer includes a negative electrode active material, a conductive agent, a binder, etc.

[0035] The negative electrode active material can be carbon-based materials such as graphite, porous carbon, hard carbon, soft carbon, and mesophase carbon microspheres, or silicon-based materials such as elemental silicon, silicon oxides, silicon-carbon composites, and silicon-nitrogen composites. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0036] The thickness of the active material layer 11b on the single electrode 11 is the single-sided dimension of the active material layer 11b measured along the thickness direction of the current collector 11a, in mm; if it is a double-sided coated structure, the thickness of the active material layer 11b on both sides can be measured separately, and the sum of the thicknesses of the active material layer 11b on both sides is M, such as Figure 4 In the case of M = M1 + M2.

[0037] The diaphragm 113 is an insulating porous structure disposed between two adjacent electrodes 11 of different polarities. It can be made of a material with good ion permeability, mechanical strength, and chemical stability. For example, it can be made of polyolefin materials such as polyethylene and polypropylene, or at least one of glass fiber, non-woven fabric, and polyvinylidene chloride. The surface of the diaphragm 113 can also be coated. The coating can be an inorganic coating and, or an organic coating. The inorganic coating material includes at least one of alumina, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite; the organic coating includes at least one of aramid coating and polyvinylidene chloride (PVDF) coating.

[0038] The protrusion 11c is a protruding structure formed by the outward protrusion of the electrode 11 surface. The protrusion 11c can be in various planar projection shapes such as circular, elliptical, triangular, or polygonal. Multiple protrusions 11c can be arranged in a regular or irregular manner on the surface of the electrode 11, and at least some of the protrusions 11c are located in the corner section 10b region of the cell 10 to compensate for the gap of the electrode 11 in the corner section 10b. The remaining protrusions 11c can also be set in the straight section 10a region of the cell 10 according to the structural requirements of the cell 10.

[0039] The protrusion 11c can be provided only on the positive electrode 11, only on the negative electrode 11, or on both the positive and negative electrode 11. In some embodiments, the protrusion 11c protrudes towards the side closer to the center of the cell 10 or towards the side away from the cell 10. The orientations of the multiple protrusions 11c can be the same or different. Preferably, multiple protrusions 11c are provided on the positive electrode 11, distributed on the straight section 10a and the corner section 10b, and all of the multiple protrusions 11c have the same orientation, protruding towards the side away from the center of the cell 10, that is, towards the outside of the cell 10.

[0040] The method for measuring the ratio K of the area of ​​the protrusion 11c located in corner segment 10b to the area of ​​the electrode 11 located in corner segment 10b is as follows: First, measure and determine the thickness h (in mm) of the battery cell 10 and the width b (in mm) of the electrode 11. Take the electrode 11 located at 1 / 2 of the total number of electrode layers in the corner segment 10b as the measurement object. After removing it from the battery cell 10 without damage, identify its outermost end furthest from the straight segment 10a (i.e., the highest point of the corner arc). Using this outermost end as the center line, take a region of length h / 4 on each side of the center line in the extension direction of the electrode 11 (the unfolded length direction X), for a total length h / 2. The area is used as the standard measurement sample. The sample is scanned and observed using an image measuring instrument or optical microscope. The planar projected area of ​​each individual protrusion 11c within the sample is measured. The area of ​​each individual protrusion 11c is multiplied by the number of protrusions 11c in the sample to obtain the total area S1 of the protrusions 11c. Simultaneously, the overall area of ​​the sample is measured, i.e., b*h / 2. By calculating the ratio of S1 to (b*h / 2), the area ratio of the protrusions 11c is obtained, i.e., K = S1 / (b*h / 2). When the edge of the measurement sample area coincides with a protrusion, if the size of a protrusion falling within the measurement sample area is greater than or equal to 50% of its area, it is counted as a complete protrusion. If the size of a protrusion falling within the measurement sample area is less than 50% of its area, it is not counted.

[0041] The method for measuring the average distance between two adjacent layers of electrodes 11 of the same polarity in the corner segment 10b of cell 10 is as follows: X-ray non-destructive imaging is performed on the corner segment of cell 10. The imaging cross-section is parallel to the plane where the electrode 11 of the straight segment 10a is located, obtaining a cross-sectional tomographic image of the electrode layer of the corner segment 10b. Since the separator 113 is non-metallic, it is not displayed in the tomographic image. The prominent bright vertical lines in the image represent the metallic current collector 11a. Adjacent current collector layers correspond to electrodes with opposite polarities. Therefore, two adjacent electrodes 11 of the same polarity are denoted as the two bright vertical lines on the tomographic image separated by one bright vertical line, for example... Figure 8 In the diagram, the red dot indicates the positive electrode. Using the center of the vertical bright line along its thickness as the measurement reference point, the distance between the measurement reference points of the corresponding vertical bright lines of two adjacent layers of electrodes 11 of the same polarity is measured along the non-protruding region of the thickness direction. This distance is taken as the distance between the diameters of these two layers of electrodes 11 of the same polarity. Since the ends of the electrodes often have bends, the vertically extending areas of the electrodes are used as the measurement positions. The straight-line distances between each layer of electrodes 11 of the same polarity are measured separately, and the average value is taken to obtain the average distance L of the corner segment 10b of the electrode 11 of the same polarity, in mm.

[0042] By providing at least a portion of a protrusion 11c on the surface of the electrode 11 located in the corner segment 10b, the protrusion 11c can compensate for the gap between adjacent electrodes 11 in the corner segment 10b, effectively reducing the gap distance between electrode 11 layers, shortening the transport path of active ions such as lithium ions in the corner segment 10b, improving the transport efficiency of ions in the corner segment 10b, reducing the occurrence of lithium plating in the corner segment 10b, reducing the risk of internal short circuit in the battery 100 caused by lithium plating, and improving the safety of use and cycle charge and discharge performance of the cell 10.

[0043] If K / (M*L) is too large, the area ratio of the protrusion 11c will be relatively large, or the thickness of the active material layer 11b and the average spacing of the electrode 11 will be relatively small. In particular, if the ratio K of the area of ​​the protrusion 11c to the area of ​​the electrode in the corner section 10b is relatively large, the excessive protrusion structure will occupy the effective space inside the cell 10 in the corner section, reducing the number of electrode 11 layers that can be arranged within the same thickness in the corner section, reducing the active material in the cell 10, and resulting in low energy density of the cell 10, which cannot meet the high energy density requirements of the battery 100. If M or L is too small, the corner section will not be affected by a large stress, which means that the hot pressing of the straight section 10a is not in place and the gap of the electrode 11 in the straight section 10a is increased. The increase in the gap in the thickness direction of the cell leads to insufficient energy density of the battery. At the same time, the thinner active material layer will further reduce the energy density of the cell 10.

[0044] If K / (M*L) is too small, the area ratio of the protrusion 11c will be relatively small, or the thickness of the active material layer 11b and the average spacing of the electrodes 11 will be relatively large. In particular, a small K ratio results in insufficient physical compensation of the protrusion 11c for the gap between the electrodes 11 in the corner section 10b, failing to effectively reduce the gap. The ion transport distance in the corner section 10b remains large, resulting in low transport efficiency and severe lithium plating. This not only causes capacity decay in the battery 100 but also increases the risk of short circuits in the cell 10. If M or L is too large, excessive hot pressing in the straight section 10a causes the gap between the electrodes 11 in the corner section 10b to widen under stress, resulting in a large ion transport distance in the corner section 10b and exacerbating the lithium plating problem. Simultaneously, a thicker active material layer 11b requires more electrolyte for wetting. If the gap between the electrodes 11 in the straight section 10a is too small, the electrolyte wetting effect will be poor, affecting the safety and cycle performance of the cell 10. Therefore, 11.0*10 -2 ≤K / (M*L)≤2307.7*10 -2 This effectively reduces the risk of lithium plating at the corner section 10b, ensuring the safety and cycle performance of cell 10 while also meeting the energy density requirements of cell 10.

[0045] The thickness Mmm of the aforementioned active material layer 11b ranges from 0.03mm to 0.21mm. For example, it can be 0.03mm, 0.035mm, 0.038mm, 0.1mm, 0.12mm, 0.15mm, 0.2mm, 0.21mm, or any value within the range of any two of these values. When Mmm is less than 0.03mm, the active material layer thickness is small, reducing the energy density of the cell 10; when Mmm is greater than 0.21mm, the thicker active material layer 11b requires more electrolyte for wetting, resulting in poor electrolyte wetting on the electrode and affecting the safety and cycle performance of the cell 10.

[0046] In a battery 100 where the main positive electrode active material is lithium iron phosphate, the thickness of the positive electrode active material ranges from 0.07 mm to 0.21 mm; in a battery 100 where the main positive electrode active material is ternary lithium, the thickness of the positive electrode active material layer ranges from 0.03 mm to 0.150 mm.

[0047] In the battery 100 where the main material of the negative electrode active material is silicon-carbon, the thickness of the negative electrode active material layer ranges from 0.03mm to 0.160mm; in the battery 100 where the main material of the negative electrode active material is graphite, the thickness of the negative electrode active material layer ranges from 0.040mm to 0.2mm.

[0048] The ratio K of the area of ​​the protrusion to the area of ​​the 10b electrode at the corner is in the range of 0.01-0.1, for example, it can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.07, 0.08, 0.09, 0.1, or a value within any two of the above values. When K is less than 0.01, the protrusion 11c fails to adequately compensate for the gap between the electrode 11 in the corner section 10b, thus failing to effectively reduce the gap. The ion transport distance in the corner section 10b remains relatively long, resulting in low transport efficiency and severe lithium plating. This not only causes capacity decay in the battery 100 but also increases the risk of short circuits in the cell 10. When K is greater than 0.1, the excessive protrusion structure occupies the effective space within the corner section of the cell 10, reducing the number of electrode 11 layers that can be arranged within the same thickness in the corner section. This reduces the amount of active material in the cell 10, leading to low energy density and failing to meet the high energy density requirements of the battery 100. The optimal range for the ratio K is 0.03-0.08. When K meets this optimal range, it can further reduce the risk of lithium plating in the corner section 10b while better ensuring the battery's energy density.

[0049] The average spacing Lmm between two adjacent layers of electrodes of the same polarity ranges from 0.10mm to 0.54mm. For example, it can be 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.54mm, or any value within the range of any two of the above values. When Lmm is less than 0.10mm, the corner section is not significantly affected by stress, which means that the hot pressing of the straight section 10a is inadequate and the gap of the electrode 11 in the straight section 10a is increased. The increased gap in the cell thickness direction leads to insufficient battery energy density. When Lmm is greater than 0.54mm, the hot pressing of the straight section 10a is excessive, causing the gap of the electrode 11 in the corner section 10b to expand under stress, resulting in a large ion transport distance in the corner section 10b and exacerbating the lithium plating problem. The preferred range for Lmm is 0.16mm-0.45mm. When Lmm meets the preferred range, the possibility of lithium plating in the battery can be reduced while ensuring the battery energy density.

[0050] Reference Figure 7 L = gap size (0.020mm-0.08mm) + separator thickness (0.07mm-0.12mm) * 2 + positive electrode thickness (0.036mm-0.228mm) + negative electrode thickness (0.034mm-0.212mm).

[0051] The preferred range for K / (M*L) is 44.4*10. -2 -714.3*10 -2 When K / (M*L) meets the above preferred range, it can ensure better energy density of the battery while making the ion transport efficiency of the corner segment 10b higher and reducing the possibility of lithium plating.

[0052] In some embodiments, a protrusion 11c is formed on one side surface of the electrode 11 along its thickness direction, and a recess 11d corresponding to the protrusion 11c is formed on the other side surface of the electrode 11 along its thickness direction.

[0053] When the protrusion 11c is formed on one side of the electrode 11, the other side of the electrode 11 will have a recess 11d formed on it due to the forming process, which matches the position and shape of the protrusion 11c. The protrusion 11c can be formed by processes such as rolling or molding.

[0054] This design simplifies the forming process of the protrusion 11c and allows it to be integrated with the preparation process of the electrode 11, reducing the manufacturing cost of the cell 10. The corresponding protrusion 11c and recess 11d make the stress distribution of the electrode 11 more uniform, avoiding local stress concentration in the electrode 11 caused by protrusion on only one side, reducing the risk of tearing of the electrode 11, and improving the structural stability of the electrode 11.

[0055] In some embodiments, active material layers 11b are provided on both sides of the current collector 11a along its thickness direction.

[0056] The active material layers 11b coated on both sides of the current collector 11a can use the same or different active material formulations. The thickness of the active material layers 11b on both sides can be consistent, or different thicknesses can be set according to the requirements of the battery cell 10.

[0057] The coating process of the double-sided active material layer 11b can be continuous coating or step-by-step coating. After coating, it is dried and rolled to ensure that the bonding force between the double-sided active material layer 11b and the current collector 11a is consistent, and avoid the problem of one-sided peeling or material falling off.

[0058] The current collector 11a has active material layers 11b on both sides, which can increase the active material content per unit area of ​​the electrode 11 and effectively improve the energy density of the cell 10. The active materials on both sides make the ion insertion and extraction of the electrode 11 more uniform during the charging and discharging process, reducing the risk of deformation and cracking of the electrode 11 due to excessive reaction on one side.

[0059] In some embodiments, the protrusion height Hmm of the protrusion 11c protruding from one side surface of the electrode 11 ranges from 0.002mm to 0.07mm.

[0060] The protrusion height of the protrusion 11c is the maximum height of the protrusion 11c protruding from the normal surface of the electrode 11. For example, Hmm can be 0.002mm, 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, etc., or a value within the range of any two of the above values.

[0061] The heights of the protrusions 11c on the electrode 11 of the corner segment 10b can be the same or different. For example, the height of the protrusions 11c on the outer side of the corner segment 10b can be larger, and the height of the protrusions 11c on the inner side of the corner segment 10b can be smaller, to accommodate the gap differences at different positions of the corner segment 10b. For example, the protrusions 11c on the corner segment 10b of the positive electrode 11 all have approximately the same protrusion height, and the protrusions 11c are linearly distributed along the extension direction of the electrode 11.

[0062] If the protrusion height is too large, it will excessively occupy the internal space of the cell 10, resulting in a reduction in the number of electrode layers 11 that can be arranged within the same thickness, thus lowering the energy density of the cell 10. Furthermore, an excessively high protrusion 11c is prone to being squeezed during cell assembly and use, leading to material loss, breakage, or even puncture of the separator 113, causing a short circuit in the cell 10. If the protrusion height is too small, it cannot effectively compensate for the gaps between the electrode layers 11 in the corner section 10b, preventing a significant reduction in ion transport distance and leaving the lithium plating problem in the corner section 10b unresolved. Therefore, by controlling the protrusion height within the range of 0.002mm to 0.07mm, it is possible to effectively compensate for the gaps between the electrode layers 11, improving ion transport efficiency, while avoiding a decrease in energy density due to improper protrusion height. Simultaneously, a suitable protrusion height also ensures the structural stability of the protrusion 11c, reducing the occurrence of material loss and breakage.

[0063] In some embodiments, the protrusion direction of the plurality of protrusions 11c is all toward the same side of the electrode 11 along its thickness direction.

[0064] All protrusions 11c protrude in the same direction, either towards the side closer to the center of the cell 10 or towards the side away from the center of the cell 10.

[0065] All protrusions 11c protrude towards the same side, which enables more uniform adhesion between adjacent electrode sheets 11, improves the compensation effect of the protrusions 11c on the gaps between electrode sheets 11, and makes the stress distribution of electrode sheets 11 more uniform, reducing local stress concentration caused by inconsistent protrusion directions, thereby improving the structural stability of electrode sheets 11. In addition, the consistent protrusion direction of the protrusions 11c facilitates standardized production, reduces the difficulty of process control, and improves the production efficiency of battery cell 10. If the protrusion directions of multiple protrusions 11c are different, with some facing the inside of battery cell 10 and some facing the outside of battery cell 10, it will lead to uneven distribution of contact gaps between adjacent electrode sheets 11, and some protrusions 11c may even collide with each other, further widening the gaps between electrode sheets 11, failing to effectively compensate for the gaps, and may also cause deformation and material loss of electrode sheets 11 due to mutual compression of protrusions 11c.

[0066] In some embodiments, the protrusion direction of the plurality of protrusions 11c is towards the side of the electrode 11 away from the center of the cell 10 along its thickness direction. That is, the protrusions 11c protrude outward from the cell 10, that is, protrude towards the housing 20.

[0067] The protrusion 11c protrudes outward toward the cell 10, which can make the protrusion 11c fit more tightly with the adjacent electrode 11 by utilizing the expansion force of the cell 10, further improving the gap filling effect and reducing lithium plating. It can also allow the protrusion 11c to absorb the expansion stress of the cell 10, relieve the squeezing force when the cell 10 expands, and reduce the risk of the electrode 11 tearing.

[0068] In some embodiments, a plurality of protrusions 11c are arranged at intervals, and the interval between two adjacent protrusions 11c ranges from 1.2mm to 5mm. For example, Dmm can be 1.2mm, 2mm, 3mm, 4mm, 5mm, etc., or a value within the range of any two of the above values.

[0069] The spacing between adjacent protrusions 11c is the straight-line distance between the centers of the two protrusions 11c. The protrusions 11c can be arranged in a matrix, linear, or arc pattern, etc.

[0070] If the spacing is too small, the protrusions 11c will be too dense, leading to a high risk of cracking and material shedding in the active material layer 11b of the electrode 11. If the spacing is too large, the protrusions 11c will be too sparse, failing to compensate for the gaps in the corner section 10b of the electrode 11, resulting in low ion transport efficiency and severe lithium plating. Therefore, by controlling the spacing within the range of 1.2mm to 5mm, the protrusions 11c are reasonably distributed on the surface of the electrode 11, achieving both the compensation effect for the gaps in the corner section 10b of the electrode 11 and improving ion transport efficiency, while avoiding the risk of cracking and material shedding caused by excessive density of the protrusions 11c.

[0071] In some embodiments, along the width direction Y of the electrode 11, the electrode 11 includes two opposing edges, at least one edge being spaced apart from the nearest protrusion 11c.

[0072] The width direction of electrode 11 is perpendicular to the extension direction of electrode 11. The two edges of electrode 11 are the two ends in the width direction, which are prone to material loss and cracking during winding and pressing.

[0073] The protrusions 11c are spaced apart from the edge of the electrode 11, such that all protrusions 11c are located within a certain area inside the edge of the electrode 11. One edge of the electrode 11 is spaced apart from the protrusion 11c, or both edges are spaced apart from the protrusion 11c.

[0074] The protrusion 11c is spaced apart from the edge of the electrode 11 to avoid the edge area of ​​the electrode 11 where material is easily dropped, thus preventing material dropping and falling off, and also ensuring the stability of the protrusion 11c structure.

[0075] In some embodiments, along the width direction of the electrode 11, the distance Gmm between the edge of the electrode 11 and the nearest protrusion 11c ranges from 0.002mm to 0.07mm. For example, Gmm can be 0.002mm, 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, or a value within the range of any two of the above values.

[0076] The distance Gmm between the edge of the electrode 11 and the nearest protrusion 11c is the vertical distance from the edge of the electrode 11 to the edge of the nearest protrusion 11c.

[0077] If the spacing Gmm is too small, the protrusion 11c will be too close to the edge area of ​​the electrode 11 where material is easily lost, posing a risk of material loss or detachment in the edge area. If the spacing Gmm is too large, the number of protrusions 11c on the inner side of the electrode 11 edge will decrease, affecting the compensation effect on the gap of the electrode 11 in the corner section 10b. Therefore, by controlling the spacing Gmm within the range of 0.002mm to 0.07mm, the structural stability of the protrusions 11c and the edge of the electrode 11 can be ensured, reducing the risk of material loss, cracking, and detachment. At the same time, a sufficient number of protrusions 11c can be ensured to achieve the compensation effect on the gap of the electrode 11 in the corner section 10b, thereby improving ion transport efficiency and reducing the risk of lithium plating.

[0078] In some embodiments, a plurality of protrusions 11c form a plurality of protrusion rows 11g distributed along the length direction X of the electrode 11. Each protrusion row 11g includes a plurality of protrusions 11c arranged linearly, wherein the angle between the arrangement direction of the plurality of protrusions 11c in each protrusion row 11g and the length direction of the electrode 11 is α°, and 15° < α° < 75°.

[0079] The length direction of the electrode 11 is the extension direction of the electrode 11, which is the direction of the wire travel when the cell 10 is wound. Multiple rows of protrusions 11g can be distributed along the length direction of the electrode 11 at equal or unequal intervals. Multiple protrusions 11c in each row of protrusions 11g are arranged linearly, and different rows of protrusions 11g can use the same or different included angles.

[0080] The protrusions 11g are arranged at an acute angle to the length of the electrode 11. Compared with the vertical arrangement along the length or width Y direction, more protrusions 11c can be set in the same area of ​​the electrode 11, increasing the distribution density of the protrusions 11c and better compensating for the gap of the electrode 11 in the corner section 10b, thus reducing the risk of lithium plating. At the same time, the oblique arrangement allows the stress of the electrode 11 during the winding and bending process to be dispersed along the arrangement direction of the protrusions 11g, avoiding stress concentration in local areas and reducing the risk of tearing or bending of the electrode 11.

[0081] In some embodiments, the orthographic projection shape of the protrusion 11c along the thickness direction of the electrode 11 is circular.

[0082] The circular protrusions 11c at different locations can have the same or different diameters. For example, the area with a larger gap in the corner section 10b (such as the electrode 11 near the outer side of the cell 10) uses a large-diameter circular protrusion 11c, while the area with a smaller gap (such as the electrode 11 near the inner side of the cell 10) uses a small-diameter circular protrusion 11c.

[0083] Compared to triangular or polygonal protrusions 11c with sharp angles, the circular protrusion 11c has no sharp corners on its surface, resulting in a more uniform stress distribution. During the winding, pressing, and charge-discharge cycles of the cell 10, it avoids scratching the separator 113, which could cause damage to the separator 113, thus improving the structural stability of the protrusion 11c and the separator 113. At the same time, the circular protrusion 11c makes surface contact with the adjacent electrode 11, resulting in a more uniform contact area and a better compensation effect for the gaps between the electrode 11, making ion transport smoother and further reducing lithium plating.

[0084] In some embodiments, the electrode 11 located in the straight section 10a is at least partially provided with a protrusion 11c.

[0085] The protrusions 11c of the straight section 10a can be provided in a local area of ​​the straight section 10a or in the entire area of ​​the straight section 10a. For example, the protrusions 11c can be provided only in the transition area between the straight section 10a and the corner section 10b, or the protrusions 11c can be provided evenly throughout the entire straight section 10a.

[0086] The protrusions 11c of the straight section 10a and the protrusions 11c of the corner section 10b can have the same or different shapes, sizes, and arrangements.

[0087] Although the straight section 10a of the battery cell 10 has undergone hot-pressing treatment, there may still be tiny gaps in some areas, especially in the transition area between the straight section 10a and the corner section 10b, where the gaps are prone to increase due to the stretching effect of the corner section 10b. Protrusions 11c in the straight section 10a can effectively compensate for these tiny gaps, reducing or avoiding the risk of lithium plating in the straight section 10a. Simultaneously, the protrusions 11c in the straight section 10a can also absorb expansion stress during the charging and discharging expansion of the battery cell 10, alleviating the overall expansion of the battery cell 10, preventing the electrode 11 from tearing, and improving the structural stability of the battery cell 10.

[0088] In some embodiments, the protrusion height of the protrusion 11c located in the straight section 10a is less than the protrusion height of the protrusion 11c located in the corner section 10b.

[0089] If the protrusion height of the raised portion 11c in the straight section 10a is the same as that of the raised portion 11c in the corner section 10b, it may cause excessive compression between the electrode sheets 11 in the straight section 10a. This will not only affect the wetting effect of the electrolyte on the electrode sheets 11, but may also cause damage and material loss to the active material layer 11b of the electrode sheets 11 in the straight section 10a, affecting the cycle performance of the cell 10. By making the protrusion height of the raised portion 11c in the straight section 10a smaller than that of the raised portion 11c in the corner section 10b, the gap in the corner section 10b can be effectively compensated, the problem of material loss and damage in the straight section 10a can be avoided, the electrolyte wetting effect can be improved, and the cycle performance of the battery 100 can be improved.

[0090] In some embodiments, the electrode 11 includes a first electrode 111 and a second electrode 112 with opposite polarities, and one of the first electrode 111 and the second electrode 112 is provided with a protrusion 11c.

[0091] The first electrode 111 can be a positive electrode 11, and the second electrode 112 can be a negative electrode 11, or the first electrode 111 can be a negative electrode 11, and the second electrode 112 can be a positive electrode 11.

[0092] By providing a protrusion 11c on only one type of electrode 11 while keeping the other electrode 11 flat, the protrusion 11c fits tightly against the flat electrode 11 surface, maximizing the gap-compensating effect without excessively occupying the internal space of the cell 10. This helps increase the number of electrode layers and improves the energy density of the cell 10. If protrusions 11c are provided on both the positive and negative electrodes 11, the protrusions 11c inside the cell 10 may come into contact with each other, such as protrusions against protrusions or recesses against recesses. This could increase the local gaps between the electrodes 11, posing a risk of local lithium plating, and would also occupy too much internal space of the cell 10, reducing the energy density of the cell 10.

[0093] In some embodiments, the first electrode 111 is provided with a protrusion 11c, and the first electrode 111 is a positive electrode 11.

[0094] The protrusion 11c is provided only on the positive electrode 11, while the negative electrode 11 keeps its surface flat. The protrusion 11c on the positive electrode 11 can be provided on the corner section 10b, or it can be provided on both the corner section 10b and the straight section 10a at the same time.

[0095] Since the positive electrode 11 has a higher structural strength than the negative electrode 11, the active material layer 11b and the current collector 11a have a stronger bonding force. Only the protrusion 11c is set on the positive electrode 11, which can effectively compensate for the gap between the electrode 11, reduce lithium plating, and reduce the risk of material loss.

[0096] In some embodiments, along the length direction X of the electrode 11, the protrusion 11c is spaced apart from the winding start end 11f and / or winding end 11e of the electrode 11, with the winding start end 11f being closer to the center of the cell 10 than the winding end 11e.

[0097] The first winding end 11f of the electrode 11 is the first end wound when the cell 10 is wound, and it is close to the center area of ​​the cell 10. The last winding end 11e is the last end wound, and it is close to the outer area of ​​the cell 10.

[0098] The protrusion 11c may be spaced apart from the winding start end 11f, spaced apart from the winding end end 11e, or spaced apart from both the winding start end 11f and the winding end end 11e simultaneously. For example, the protrusion 11c on the positive electrode sheet 11 is spaced apart from both the winding start end 11f and the winding end end 11e, and the distance between the protrusion 11c and the winding start end 11f is greater than the distance between the protrusion 11c and the winding end end 11e.

[0099] The winding start end 11f and winding end 11e of the electrode 11 are stress concentration areas during the winding process of the battery cell 10. The winding start end 11f is close to the center of the battery cell 10, has a large winding curvature, and has highly concentrated stress. The winding end 11e may need to be connected to the electrode tab 12 of the battery cell 10, which requires high structural stability. The latter may need to be secured with adhesive tape. The protrusion 11c is spaced apart from the winding start end 11f and / or the winding end 11e, which allows the protrusion 11c to avoid the stress concentration area, ensuring the structural stability of the protrusion 11c and the beginning and end of the electrode 11, and reducing the risk of the electrode 11 tearing and the protrusion 11c falling off.

[0100] In some embodiments, starting from the winding beginning 11f of the electrode 11, the electrode 11 is wound multiple times, with at least N1 turns without protrusions 11c, where N1≤10.

[0101] N1 can be any integer from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, preferably N is 3-7.

[0102] The first few turns of the winding start 11f of the battery cell 10 are close to the central region of the battery cell 10, with small winding curvature, high stress concentration, and small gaps between the electrode sheets 11, requiring almost no gap compensation. The absence of protrusions 11c in the first N1 turns allows the electrode sheets 11 in the central region of the battery cell 10 to remain flat, reducing stress concentration and improving the structural stability of the electrode sheets 11. Simultaneously, the protrusions 11c are introduced starting from the N+1th turn, effectively compensating for gaps in the non-central region of the battery cell 10 and reducing the risk of lithium plating.

[0103] In some embodiments, starting from the winding beginning 11f of the electrode 11, the electrode 11 is wound multiple times, and no protrusion 11c is provided for the last N2 turns, where N2≤10.

[0104] N2 can be any integer from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, with N2 preferably being 3-7.

[0105] The second to last N2 turns of the electrode 11 are located on the outer side of the electrode 11 closest to the cell 10 and the cell housing 20. This area is prone to material loss due to pressure from the housing 20 during cell 10 assembly (installation) and charge / discharge expansion. The absence of protrusions 11c on the second to last N2 turns ensures the electrode 11 remains flat on the outer side of the cell 10, preventing material loss due to pressure from the housing 20 during installation and charge / discharge expansion. Furthermore, the protrusions 11c on the turns preceding the second to last N2 turns effectively compensate for gaps in the main areas of the electrode 11, reducing the risk of lithium plating.

[0106] In some embodiments, when the thickness of the cell 10 is greater than or equal to 20 mm, the area of ​​the protrusion 11c located in the corner segment 10b is 0.03 to 0.1 times the area of ​​the electrode 11 located in the corner segment 10b.

[0107] The thickness of the cell 10 is the dimension along the pressing direction of the cell 10. The greater the thickness of the cell 10, the more layers of electrode 11 there are in the corner section 10b, and the larger the gap generated by the hot pressing and stretching of the electrode 11 is. A higher proportion of the area of ​​the protrusion 11c is required to effectively compensate for the gap. Increasing the lower limit of K can increase the distribution density of the protrusion 11c, effectively compensate for the large gap in the corner section 10b of the thick cell 10, shorten the ion transport distance, improve the ion transport efficiency, effectively reduce the risk of lithium plating, and ensure the safety of the thick cell 10 in use. At the same time, when the cell 10 expands during charging and discharging, the protrusion 11c can better absorb the expansion stress, improving the structural stability of the thick cell 10.

[0108] In some embodiments, when the length of the straight section 10a accounts for less than or equal to 85% of the total length of the cell 10, the thickness Mmm of the active material layer 11b on the single electrode 11 ranges from 0.07mm to 0.210mm.

[0109] The total length of the cell 10 is the overall dimension of the cell 10 along the straight section 10a. The smaller the proportion of the length of the straight section 10a, the larger the proportion of the corner section 10b of the cell 10, the higher the overall bending degree of the cell 10, the lower the ion transport efficiency of the corner section 10b, and the greater the difficulty of the electrolyte wetting the electrode 11.

[0110] This design avoids excessive thickness of the active material layer 11b, which would lead to insufficient wetting of the electrode 11 by the electrolyte, excessive ion transport distance, and lithium plating problem at the corner section 10b.

[0111] In some embodiments, the thickness M mm of the active material layer 11b on the monolithic electrode 11 ranges from 0.03 mm to 0.21 mm; and / or, the average spacing L mm between two adjacent layers of electrodes 11 of the same polarity located in the corner segment 10b ranges from 0.104 mm to 0.544 mm.

[0112] If M is too large, it will reduce the wetting efficiency of the electrolyte on the electrode 11, prolong the ion transport distance, exacerbate the lithium plating problem at the corner section 10b, and also reduce the structural strength of the electrode 11. If M is too small, it will reduce the amount of active material loaded on the electrode 11, resulting in a significant decrease in the energy density of the cell 10. Therefore, by controlling M within the range of 0.03mm-0.210mm, it is possible to ensure the energy density of the cell 10, improve the wetting efficiency of the electrolyte, shorten the ion transport distance, reduce the risk of lithium plating, and at the same time ensure the structural strength of the electrode 11.

[0113] If L is too large, the gap between the electrode 11 in the corner section 10b will be too large, resulting in an excessively long ion transport distance, low transport efficiency, and severe lithium plating. If L is too small, the hot-pressing process of the straight section 10a of the cell 10 will be inadequate, increasing the gap between the electrode 11 in the straight section 10a and reducing the energy density of the cell 10. Therefore, by controlling L within the range of 0.104mm-0.544mm, the hot-pressing effect of the straight section 10a of the cell 10 can be guaranteed, improving the structural compactness and energy density of the cell 10, while avoiding an excessively large gap between the electrode 11 in the corner section 10b, thus improving ion transport efficiency and reducing the risk of lithium plating.

[0114] In some embodiments, the area of ​​a single protrusion 11c ranges from 0.07 mm. 2 ~0.79mm 2 ; and / or, the area of ​​the protrusion 11c located in the corner segment 10b is in the range of 0.01-0.1 of the area of ​​the electrode 11 located in the corner segment 10b. For example, the area of ​​a single protrusion 11c may be 0.07 mm². 2 0.1mm 2 0.2mm 2 0.3mm 2 0.4mm 2 0.5mm 2 0.6mm 2 0.7mm 2 0.79mm 2 Values ​​equal to or within the range of any two of the above values.

[0115] The area of ​​a single protrusion 11c is the planar projection area of ​​the single protrusion 11c along the thickness direction of the electrode 11.

[0116] If the area of ​​a single protrusion 11c is too large, it will cause localized stress concentration in the electrode 11, easily leading to material loss and cracking. It will also occupy too much internal space in the cell 10, affecting the number of electrode layers. If the area of ​​a single protrusion 11c is too small, it cannot effectively compensate for the gaps between the electrode 11, resulting in poor gap compensation. Therefore, by controlling the area of ​​a single protrusion 11c to be within 0.07 mm... 2 ~0.79mm 2 Within this range, it can effectively compensate for the gaps in the electrode 11, while avoiding stress concentration and space occupation problems caused by excessive area, thus ensuring the structural stability of the electrode 11 and the energy density of the cell 10.

[0117] If K is too large, it will reduce the number of electrode layers 11 for the same thickness of battery 100, thus reducing the energy density of cell 10. If K is too small, the protrusion 11c will not be able to adequately compensate for the gaps, resulting in severe lithium plating. Therefore, by controlling K within the range of 0.01-0.1, it is possible to ensure that the protrusion 11c effectively compensates for the gaps in the corner section 10b, reducing the risk of lithium plating, while also avoiding a decrease in the energy density of cell 10 due to excessive K. This balances the safety and energy density of cell 10.

[0118] In some embodiments, a battery 100 is provided, including a housing 20 and a battery cell 10 disposed within the housing 20, wherein the battery cell 10 is the battery cell 10 in any of the above embodiments.

[0119] A housing is a component used to provide a space to house electrode assemblies and other parts and isolate them from the outside environment. Housing 20 generally includes a body with an opening at at least one end and a receiving cavity. The opening of housing 20 can be closed by a cover to seal and isolate the internal environment of the battery cell 100 from the external environment.

[0120] The materials used for the outer casing include, but are not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, and aluminum-plastic film. The materials used for the cover include, but are not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, and aluminum-plastic film.

[0121] The casing 20 may be filled with an electrolyte, which may consist of a solvent, an electrolyte salt, and additives. The solvent may be a carbonate, the electrolyte salt may be a lithium salt, and the additive may be vinylene carbonate. The electrolyte provides an ion transport medium for the electrochemical reaction of the cell 10. In some embodiments, the battery 100 adopts an aluminum alloy hard casing 20, and one or more (e.g., two) wound cells 10 are disposed inside the casing 20. The casing 20 is filled with a carbonate electrolyte. The positive electrode 11 of the cell 10 is connected to the positive electrode post of the casing 20, and the negative electrode 11 is connected to the negative electrode post of the casing 20.

[0122] In some embodiments, the housing 20 may include a housing body 21 and a cover 22. The housing body 21 may have an opening on one side, and the cover 22 covers the opening on one side of the housing body 21 and is welded to the housing 20. The housing body 21 may have openings on both sides, with a cover 22 covering each opening. In some embodiments, the cover 22 is provided with electrode terminals 30 that are electrically connected to the tabs 12. The tabs 12 may be directly connected to the electrode terminals 30 or connected via an adapter. The electrode terminals 30 may be divided into positive terminals and negative terminals. The positive terminal is electrically connected to the positive tab 12, and the negative terminal is electrically connected to the negative tab 12, such as by welding, conductive adhesive bonding, or other methods to achieve the electrical connection.

[0123] The tab is located on one side of the positive / negative current collector 11a and is separately / integrated with the current collector. It is electrically connected to the current collector to conduct current through the corresponding current collector. The tab is made of a metal material with good conductivity (such as copper, aluminum, copper or nickel).

[0124] Electrode terminals are used to electrically connect electrode assemblies located inside the housing to external devices (adjacent batteries or other electrical equipment) located outside the housing. The battery can discharge to external devices through the cell output terminals (tabs) and the external device output terminals (terminal assembly). An external power source can charge the battery through the terminal assembly and the tabs. The terminal assembly can be directly electrically connected to the cell tabs, or it can be electrically connected to the tabs through metal adapters.

[0125] Electrode terminals include, but are not limited to, metals such as copper, aluminum, aluminum alloy, and copper-aluminum alloy.

[0126] Because the cell 10 effectively reduces the risk of lithium plating at the corner section 10b by setting the protrusion 11c and adjusting the K / (M*L) parameter, it improves the safety and cycle performance of the cell 10. Therefore, the overall cycle life of the battery 100 is longer and the safety is higher, which can effectively avoid safety accidents such as short circuits and fires caused by lithium plating. At the same time, while ensuring safety, the cell 10 also takes into account high energy density. Therefore, the energy density of the battery 100 can also be effectively guaranteed to meet the power supply needs of various electrical devices.

[0127] In some embodiments, the battery 100 includes at least two stacked cells 10, with the straight sections 10a of the at least two cells 10 arranged opposite each other. When the thickness W mm of the battery 100 is greater than or equal to 40 mm, 44.4*10 -2 ≤K / (M*L)≤2307.7*10 -2 .

[0128] The flat section 10a of the cell 10 is its large surface. The arrangement of the large surfaces can maximize the use of the internal space of the battery 100 casing 20 and improve the overall energy density of the battery 100.

[0129] The number of cells 10 can be set to 2, 3, 4, etc., depending on the capacity requirements of the battery 100. The stacked cells 10 are electrically connected through conductive connectors, and can be connected in series, parallel or mixed.

[0130] The thickness W of the battery 100 is the dimension along the stacking direction of the cells 10. The greater the thickness of the battery 100, the more cells 10 are stacked, and the larger the overall gap between the electrode plates 11 is. Therefore, the range of / (M*L) needs to be further limited.

[0131] This design effectively compensates for the overall gaps between the stacked cells 10, reduces the risk of lithium plating, ensures the safety of the thick battery 100, and also takes into account the overall energy density of the battery 100 to meet the power supply needs of various high-capacity electrical devices. In addition, the limitation of this parameter range also allows the stacked cells 10 to better absorb the overall expansion stress during charging and discharging, thereby improving the structural stability and cycle performance of the thick battery 100.

[0132] Measurement methods for dimensions, area, etc. Use measuring instruments such as micrometers or calipers to measure parameters such as length, width, distance, and thickness. The area is calculated from the measured parameters such as length, width, distance, and thickness.

[0133] The method for measuring the thickness M of the active material layer 11b on a single electrode 11 is as follows: Remove the electrode from the battery and take at least 10 measurement points along the electrode's extension direction, with a distance of at least 20 mm between adjacent measurement points. Measure the thickness of the electrode at each point and take the average value as the electrode thickness M1. Then, at each measurement point, scrape off the active material layer from the electrode surface (if the current collector has an active material layer coated on one or both sides, scrape off all active material layers), leaving the current collector foil in the electrode. Measure the thickness of the current collector foil and take the average value as the current collector thickness M2. The thickness M of the active material layer 11b on a single electrode 11 is M = M1 - M2.

[0134] Battery manufacturing (1) Preparation of the positive electrode: The prepared positive electrode active material, conductive agent (e.g., acetylene black), and binder (e.g., PVDF) are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector foil, air-dried at room temperature, transferred to an oven for further drying, and then rolled to obtain a positive electrode sheet.

[0135] Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98): (4~1): (4~1).

[0136] (2) Preparation of negative electrode: The negative electrode active material, conductive agent (e.g., acetylene black), thickener (e.g., carboxymethyl cellulose (CMC)), and binder (e.g., styrene-butadiene rubber (SBR)) are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, the negative electrode sheet is obtained by rolling.

[0137] Specifically, the ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0138] (3) Processing of the protruding part of the electrode: The positive and / or negative electrode sheets after roll forming are subjected to secondary roll forming. During the secondary roll forming, the electrode sheets are sandwiched between a first roller and a second roller. The surface of the first roller is provided with a rubber layer, and the surface of the second roller is provided with a protrusion (protrusion height 0.1-0.5mm) to cooperate with the first roller. During the secondary roll forming, the protrusion is formed on the surface of the electrode sheet. The depth and size of the protrusion are controlled by controlling the pressure of the second roller (pressure range 0.01MPa to 0.3MPa).

[0139] (4) Preparation of electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0140] (5) Preparation of the diaphragm: Polyethylene film is selected as the diaphragm.

[0141] (6) Preparation of lithium-ion batteries: The positive electrode, separator, and negative electrode are stacked in sequence and wound to form a bare cell. The bare cell is then placed in a prismatic battery casing. The battery is dried, injected with electrolyte, and then packaged, allowed to stand, formed, and calibrated to obtain a lithium-ion battery.

[0142] In the selection of materials for the battery, this application may also select other materials, not limited to the materials limited by the above preparation method. The positive electrode active material may be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt and manganese, and lithium manganese iron phosphate; the negative electrode active material may be selected from one or more negative electrode active main materials, such as artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0143] The conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene, and carbon nanofibers.

[0144] The adhesive includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0145] The solvent can be deionized water, NMP (N-methylpyrrolidone), alcohol, ether, ketone or other types of pyrrolidone, etc.

[0146] The positive electrode current collector foil can be a metal foil or a composite current collector. For example, as a metal foil, it can be made of stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0147] The negative electrode current collector foil can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium, and can be surface-plated with silver. Composite current collectors may include a polymer base layer and a metal layer. Composite current collectors can be formed by forming metal materials (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on a polymer base material (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0148] The testing method is as follows: Test Method 1: Battery Capacity Retention Rate (used to measure lithium plating on the electrodes) Following the battery preparation method described above, 50 batteries were prepared for each embodiment and comparative example, with all other test conditions remaining consistent. The batteries were placed in a fixture and a force of 3000 N was applied. The batteries were placed at room temperature (20°C) until thermal equilibrium was reached. They were then charged at a constant current of 0.33 C to the upper limit voltage, and then charged at a constant voltage of 0.33 C until the current dropped to 0.05 C. After standing for 30 minutes, the batteries were discharged at a constant current of 0.33 C to the lower limit voltage. This process was repeated three times to obtain the third discharge capacity Q1, which was taken as the fixed capacity of the battery.

[0149] The battery is then charged at room temperature with a constant current of 0.33C to the upper limit voltage, and then charged with a constant voltage of 0.33C until the current drops to 0.05C. After resting for 30 minutes, the battery is discharged with a constant current of 0.33C to the lower limit voltage. This constitutes one cycle. After n cycles, the battery discharge capacity Qn of the nth cycle is recorded. The battery capacity retention rate is calculated using the formula "Battery capacity retention rate = Qn / Q1 * 100%". The number of cycles n when the capacity retention rate first falls below 80% is recorded as the number of cycles for that battery. If a short circuit occurs during the cycle, the number of cycles in which the short circuit occurs is recorded as the number of cycles n for that battery. The average number of cycles n of 50 batteries from the same embodiment or comparative example is taken to obtain n0 as the average number of cycles for that group of batteries. If n0 is less than 1200, it is considered unqualified; if n0 is greater than or equal to 1200 and less than 1400, it is considered qualified; and if n0 is greater than or equal to 1400, it is considered good.

[0150] For different systems, the upper and lower voltage limits of a single battery need to be adjusted accordingly: Lithium iron phosphate (LFP) - upper limit voltage 3.65V, lower limit voltage 2.5V; Nickel-cobalt-manganese ternary NCM - upper limit voltage 4.25V, lower limit voltage 2.5V; Lithium manganese iron phosphate (LFMP) - upper limit voltage 4.25V, lower limit voltage 2.5V; Lithium nickel manganese oxide - upper limit voltage 4.8V, lower limit voltage 3.5V.

[0151] In this test, the active material for the positive electrode of the battery was selected from a nickel-cobalt-manganese ternary LiNi alloy. 0.6 Co 0.2 Mn 0.2 Taking O2 as an example, the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; the negative electrode active material is selected from artificial graphite, and the ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2.

[0152] Test Method 2: Battery Mass Energy Density Following the battery fabrication method described above, corresponding batteries were fabricated for each embodiment and comparative example. The casing dimensions of each battery were identical, the cell dimensions corresponded to the casing dimensions, and other structures within the batteries were completely identical. A reference battery was then fabricated, with dimensions identical to those of the embodiments and comparative examples, but without protrusions on the electrodes.

[0153] Use an electronic scale to measure the mass of each battery, denoted as W, in kg.

[0154] Place the battery at room temperature (20°C) until it reaches thermal equilibrium. Then charge it to the upper limit voltage with a constant current of 0.33C. Then charge it to the lower limit voltage with a constant voltage of 0.33C until the current drops to 0.05C. After standing for 30 minutes, discharge the battery to the lower limit voltage with a constant current of 0.33C. Repeat the above steps for a total of 3 charge and discharge cycles. The discharge capacity Q1 of the third charge and discharge cycle is obtained and is taken as the constant capacity V of the battery, in Ah.

[0155] The mass energy density of a battery is calculated as: constant capacity V / battery mass W. The mass energy density of the reference battery is denoted as W0, and the mass energy densities of the batteries in each embodiment and comparative example are denoted as Wn. When Wn / W0 is greater than or equal to 0.95, the battery mass energy density is considered good; when Wn / W0 is greater than or equal to 0.92 and less than 0.95, the battery mass energy density is considered acceptable; when Wn / W0 is less than 0.92, the battery mass energy density is considered unacceptable.

[0156] For different systems, the upper and lower voltage limits of a single battery need to be adjusted accordingly: Lithium iron phosphate (LFP) - upper limit voltage 3.65V, lower limit voltage 2.5V; Nickel cobalt manganese ternary NCM - upper limit voltage 4.25V, lower limit voltage 2.5V; Lithium manganese iron phosphate (LFMP) - upper limit voltage 4.25V, lower limit voltage 2.5V; Lithium nickel manganese oxide - upper limit voltage 4.8V, lower limit voltage 3.5V.

[0157] In this test, the active material for the positive electrode of the battery was selected from a nickel-cobalt-manganese ternary LiNi alloy. 0.6 Co 0.2 Mn 0.2 Taking O2 as an example, the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; the negative electrode active material is selected from artificial graphite, and the ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2.

[0158] The differences between the various embodiments and comparative examples are shown in the table below.

[0159] The example table is as follows:

[0160] As shown in the table above, the K / (M*L) values ​​for Examples 1 to 17 are all around 11.0*10. -2 Up to 2307.7*10 -2 Within the specified range, the battery capacity retention rate and the battery mass energy density all reached the acceptable or good level; however, the K / (M*L) values ​​of Comparative Examples 1 to 4 all exceeded the above range, the battery mass energy density of Comparative Examples 1 and 2 were unacceptable, and the battery capacity retention rate of Comparative Examples 3 and 4 were unacceptable.

[0161] Therefore, it can be seen that by comprehensively controlling the area ratio K of the protrusion in the corner section of the electrode, the thickness M of the active material layer in the electrode, and the average spacing L between two adjacent layers of electrodes of the same polarity in the corner section, the three factors can be made to satisfy 11.0*10. -2 ≤K / (M*L)≤2307.7*10 -2 This design ensures that the protrusions effectively compensate for the gaps in the corner sections, shortening the ion transport distance, improving ion transport efficiency, avoiding or reducing lithium plating, and ensuring battery safety and cycle performance; it also takes into account the battery's energy density.

[0162] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, The battery cell (10) includes a straight section (10a) and a corner section (10b). The cell (10) is formed by winding two electrodes (11) with opposite polarities and a separator (113). The separator (113) is located between the two electrodes (11). Each electrode (11) includes a current collector (11a) and an active material layer (11b) disposed on at least one surface of the current collector (11a). The thickness of the active material layer (11b) on a single electrode (11) is M mm. The electrode (11) has a plurality of protrusions (11c) formed on one side surface. At least part of each of the protrusions (11c) is located in the corner segment (10b). The area of ​​the protrusions (11c) in the corner segment (10b) is equal to the area of ​​the electrode (11) in the corner segment (10b) by a ratio of K. The average spacing between two adjacent layers of electrodes (11) of the same polarity in the corner segment (10b) is L mm, satisfying 11.0*10. -2 ≤K / (M*L)≤2307.7*10 -2 .

2. The battery cell according to claim 1, characterized in that, The electrode (11) has a protrusion (11c) on one side surface along its thickness direction, and a recess (11d) corresponding to the protrusion (11c) is formed on the other side surface along its thickness direction.

3. The battery cell according to claim 2, characterized in that, The current collector (11a) has active material layers (11b) on both sides of its thickness direction.

4. The battery cell according to claim 1, characterized in that, The protrusion direction of the plurality of protrusions (11c) is all toward the same side of the electrode (11) along its thickness direction.

5. The battery cell according to claim 4, characterized in that, The protrusion direction of the plurality of protrusions (11c) is towards the side of the electrode (11) away from the center of the cell (10) along its thickness direction.

6. The battery cell according to claim 1, characterized in that, The multiple protrusions (11c) are arranged at intervals, and the interval Dmm between two adjacent protrusions (11c) ranges from 1.2mm to 5mm.

7. The battery cell according to any one of claims 1-6, characterized in that, The protrusion height Hmm of the protrusion (11c) protruding from one side surface of the electrode (11) ranges from 0.002mm to 0.07mm.

8. The battery cell according to any one of claims 1-6, characterized in that, Along the width direction of the electrode (11), the electrode (11) includes two opposing edges, at least one of the edges being spaced apart from the nearest protrusion (11c).

9. The battery cell according to claim 8, characterized in that, Along the width direction of the electrode (11), the distance Gmm between the edge of the electrode (11) and the nearest protrusion (11c) ranges from 0.002mm to 0.07mm.

10. The battery cell according to any one of claims 1-6, characterized in that, The plurality of protrusions (11c) form a plurality of protrusion rows (11g) distributed along the length direction of the electrode (11), each of the protrusion rows (11g) including a plurality of protrusions (11c) arranged linearly, wherein the angle between the arrangement direction of the plurality of protrusions (11c) in each of the protrusion rows (11g) and the length direction of the electrode (11) is α°, 15°<α°<75°.

11. The battery cell according to any one of claims 1-6, characterized in that, The protrusion (11c) has a circular shape when projected along the thickness direction of the electrode (11).

12. The battery cell according to any one of claims 1-6, characterized in that, The electrode (11) located in the straight section (10a) is at least partially provided with the protrusion (11c).

13. The battery cell according to claim 12, characterized in that, The protrusion height of the protrusion (11c) located in the straight section (10a) is less than the protrusion height of the protrusion (11c) located in the corner section (10b).

14. The battery cell according to any one of claims 1-6, characterized in that, The electrode (11) includes a first electrode (111) and a second electrode (112) with opposite polarities, and one of the first electrode (111) and the second electrode (112) is provided with the protrusion (11c).

15. The battery cell according to claim 14, characterized in that, The first electrode (111) is provided with the protrusion (11c), and the first electrode (111) is a positive electrode (11).

16. The battery cell according to any one of claims 1-6, characterized in that, Along the length direction of the electrode (11), the protrusion (11c) is spaced apart from the winding start end (11f) and / or winding end end (11e) of the electrode (11), and the winding start end (11f) is closer to the center of the cell (10) than the winding end end (11e).

17. The battery cell according to claim 16, characterized in that, The electrode (11) is wound multiple times, and from the first winding end (11f) of the electrode (11), at least N1 turns are without the protrusion (11c), where N1≤10.

18. The battery cell according to claim 16, characterized in that, The electrode (11) is wound multiple times. Starting from the first winding end (11f) of the electrode (11), the protrusion (11c) is not provided for the next N2 turns, where N2≤10.

19. The battery cell according to any one of claims 1-6, characterized in that, When the thickness of the cell (10) is greater than or equal to 20 mm, the ratio of the area of ​​the protrusion (11c) located in the corner segment (10b) to the area of ​​the electrode (11) located in the corner segment (10b) is in the range of 0.03 to 0.

1.

20. The battery cell according to any one of claims 1-6, characterized in that, When the length of the straight section (10a) is less than or equal to 85% of the total length of the cell (10), the thickness Mmm of the active material layer (11b) on a single electrode (11) ranges from 0.07mm to 0.21mm.

21. The battery cell according to any one of claims 1-6, characterized in that, The thickness Mmm of the active material layer (11b) on the single electrode (11) ranges from 0.03mm to 0.21mm; and / or, The average spacing Lmm between two adjacent layers of the same polarity electrode (11) located in the corner segment (10b) ranges from 0.104mm to 0.544mm.

22. The battery cell according to any one of claims 1-6, characterized in that, The area of ​​a single protrusion (11c) ranges from 0.07 mm. 2 ~0.79mm 2 ; and / or, The area of ​​the protrusion (11c) located in the corner segment (10b) is in the range of 0.01-0.1 as a percentage of the area of ​​the electrode (11) located in the corner segment (10b).

23. A battery, characterized in that, include: The housing (20) and the battery cell (10) disposed within the housing (20), wherein the battery cell (10) is the battery cell (10) as described in any one of claims 1-22.

24. The battery according to claim 23, characterized in that, The battery (100) includes at least two stacked cells (10), with the straight sections (10a) of the at least two cells (10) arranged opposite each other. When the thickness W mm of the battery (100) is greater than or equal to 40 mm, 44.4*10 -2 ≤K / (M*L)≤2307.7*10 -2 .

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