Battery cell and electric equipment

Abstract

The invention provides a battery cell and electric equipment. The battery cell comprises an electrode assembly and an insulating part, the electrode assembly is of a winding structure, in the winding direction of the electrode assembly, a positive pole piece of the electrode assembly is provided with a positive ending end, and a negative pole piece of the electrode assembly is provided with a negative ending section exceeding the positive ending end. The insulating part is arranged on the side, close to the positive electrode ending end, of the negative electrode ending end, and the insulating part and the positive electrode piece are arranged in the winding direction, so that the uniformity of acting force between the electrode assembly and the shell during expansion is improved; the risk that the ring layer, close to the winding center, of the electrode assembly sinks after the electrode assembly is subjected to the acting force of the shell at the corresponding position of the positive ending end after expansion or the degree that the ring layer, close to the winding center, of the electrode assembly sinks after the electrode assembly is subjected to the acting force of the shell at the corresponding position of the positive ending end after expansion is relieved; and the yield of the battery cell and the safety performance of the battery cell are improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell and an electrical device. Background Art

[0002] With the rapid development of new energy technologies, battery cells have been widely used in electronic equipment, electric vehicles, electric two-wheeled vehicles, power tools, etc. As the application of battery cells becomes more and more extensive, higher requirements are placed on the safety of battery cells. Summary of the invention

[0003] The embodiments of the present application provide a battery cell and an electrical device to improve the safety performance of the battery cell.

[0004] In the first aspect, an embodiment of the present application provides a battery cell, comprising an electrode assembly and an insulating member. The electrode assembly is a winding structure, comprising a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator insulates and isolates the positive electrode sheet from the negative electrode sheet, and along the winding direction of the electrode assembly, the positive electrode sheet has a positive electrode tail end, and the negative electrode sheet has a negative electrode tail section that exceeds the positive electrode tail end. The insulating member is disposed on one side of the negative electrode tail section close to the positive electrode tail end, and the insulating member and the positive electrode sheet are arranged along the winding direction.

[0005] In one or more of the above optional embodiments, an insulating member is arranged on one side of the negative electrode tail section near the positive electrode tail end, and the insulating member and the positive electrode sheet are arranged along the winding direction, that is, the insulating member fills the space between the positive electrode tail end and the negative electrode tail end of the negative electrode sheet, and fills the gap on one side of the negative electrode tail section near the positive electrode tail end, thereby improving the uniformity of the force acting on the outer shell when the electrode assembly expands, reducing the risk of the electrode assembly being inwardly sunken at the winding center after the electrode assembly is subjected to the force of the outer shell at the corresponding position of the positive electrode tail end after expansion, or reducing the degree of inwardly sunken at the winding center after the electrode assembly is subjected to the force of the outer shell at the corresponding position of the positive electrode tail end after expansion, thereby reducing the risk of short-circuit failure caused by puncturing the isolation membrane due to the inwardly sunken electrode layer near the winding center during a drop mechanical test or when the battery cell is in a drop condition, thereby improving the yield of the battery cell and the safety performance of the battery cell. In addition, by providing the insulating member, the stress at the contact position between the negative electrode tail section and the positive electrode tail end can be released, thereby reducing the risk of the outermost circle of the negative electrode being broken.

[0006] In some embodiments of the first aspect of the present application, along the winding direction, the positive electrode sheet and the insulating member are spaced apart.

[0007] In one or more of the above optional embodiments, the positive electrode plate and the insulating member are spaced apart along the winding direction, which is beneficial to reducing the risk of overlapping between the insulating member and the positive electrode tail section during the manufacturing process, thereby reducing the risk of increased stress concentration and worsening the risk of inward collapse of the electrode assembly near the winding center due to the overlap between the insulating member and the positive electrode tail section during the manufacturing process, thereby reducing the risk of short-circuit failure caused by puncturing the isolation membrane due to the inward collapse of the electrode assembly near the winding center during a drop mechanical test or when the battery cell is in a drop condition, thereby improving the yield of the battery cell and the safety performance of the battery cell.

[0008] In some embodiments of the first aspect of the present application, along the winding direction, a distance between the positive electrode tail end and the insulating member is L1, and 0.1 mm≤L1≤0.8 mm.

[0009] In one or more of the above optional embodiments, L1≥0.1mm is conducive to reducing the risk of overlapping of the insulating member and the positive electrode tail section during the manufacturing process, thereby reducing the risk of stress concentration due to the overlap of the insulating member and the positive electrode tail section during the manufacturing process, and worsening the risk of the electrode assembly near the winding center. L1≤0.8mm, the spacing between the insulating member and the positive electrode tail end in the winding direction is controlled within a reasonable range, thereby effectively alleviating the stress concentration of the negative electrode sheet at the corresponding position of the positive electrode tail end, and then effectively alleviating the problem of the electrode assembly near the winding The problem of the inward collapse of the coil, thereby reducing the risk of puncturing the separator due to the inward collapse of the electrode assembly near the winding, and improving the yield and safety performance of the battery cell.

[0010] In some embodiments of the first aspect of the present application, 0.2 mm ≤ L1 ≤ 0.6 mm.

[0011] In one or more of the above optional embodiments, L1≥0.2mm is conducive to further reducing the risk of overlapping of the insulating member and the positive electrode tail section during the manufacturing process, thereby further reducing the risk of stress concentration due to the overlap of the insulating member and the positive electrode tail section during the manufacturing process, and worsening the risk of the electrode assembly near the winding center. L1≤0.6mm, the spacing between the insulating member and the positive electrode tail end in the winding direction is controlled within a reasonable range, thereby further effectively alleviating the stress concentration of the negative electrode sheet at the corresponding position of the positive electrode tail end, and then effectively alleviating the problem of the electrode assembly near the winding The layer is sunken, thereby further reducing the risk of puncturing the separator due to the electrode assembly near the winding The layer is sunken, and the yield and safety performance of the battery cell are improved.

[0012] In some embodiments of the first aspect of the present application, along the winding direction, the negative electrode tail section extends beyond an end of the insulating member away from the positive electrode tail end.

[0013] In one or more of the above optional embodiments, along the winding direction, the negative electrode tail section exceeds the end of the insulating member away from the positive electrode tail end, so that the insulating member is located in the space between the positive electrode tail end and the negative electrode tail end of the negative electrode pole piece, and fills in the gap on one side of the negative electrode tail section close to the positive electrode tail end, thereby alleviating the stress concentration at the gap position on one side of the negative electrode tail section close to the positive electrode winding tail end, thereby facilitating the problem of the electrode assembly's coil layer sinking near the winding center, reducing the risk of the separator being punctured due to the coil layer sinking near the winding of the electrode assembly, and improving the yield and safety performance of the battery cell. Along the winding direction, the negative electrode tail section exceeds the end of the insulating member away from the positive electrode tail end, and also avoids the insulating member occupying extra space inside the battery cell and losing energy density.

[0014] In some embodiments of the first aspect of the present application, along the winding direction, the length of the insulating member is L2, the length of the negative electrode tail section is L3, and 0.6≤L2 / L3≤0.95.

[0015] In one or more of the above optional embodiments, L2 / L3≥0.6, effectively alleviating the stress concentration of the negative electrode sheet at the corresponding position of the positive electrode tail end, thereby effectively alleviating the problem of the electrode assembly near the winding center. L2 / L3≤0.95 is conducive to reducing the risk of overlapping between the insulating part and the positive electrode tail section during the manufacturing process, thereby further reducing the risk of stress concentration due to the overlap between the insulating part and the positive electrode tail section during the manufacturing process, and worsening the problem of the electrode assembly near the winding center.

[0016] In some embodiments of the first aspect of the present application, 0.7≤L2 / L3≤0.85.

[0017] In one or more of the above optional embodiments, L2 / L3≥0.7, which further effectively alleviates the stress concentration of the negative electrode sheet at the corresponding position of the positive electrode tail end, thereby effectively alleviating the problem of the electrode assembly near the winding center. L2 / L3≤0.85 is conducive to further reducing the risk of overlapping between the insulating part and the positive electrode tail section during the manufacturing process, thereby further reducing the risk of increasing stress concentration and worsening the problem of the electrode assembly near the winding center due to the overlap between the insulating part and the positive electrode tail section during the manufacturing process.

[0018] In some embodiments of the first aspect of the present application, the thickness of the insulating member is smaller than the thickness of the positive electrode plate at the positive electrode tail end.

[0019] In one or more of the above optional embodiments, the thickness of the insulating part is smaller than the thickness of the positive electrode plate at the positive electrode tail end, which is beneficial to alleviate the stress concentration at the gap position on one side of the negative electrode plate near the positive electrode tail end, and the insulating part will not generate new stress concentration points, effectively improving the problem of the electrode assembly's circle collapse near the winding center, thereby reducing the risk of short-circuit failure caused by puncturing the isolation membrane due to the collapse of the electrode assembly near the winding center during a drop mechanical test or when the battery cell is in a drop condition, thereby improving the yield of the battery cell and the safety performance of the battery cell.

[0020] In some embodiments of the first aspect of the present application, the thickness of the insulating member is H1, the thickness of the positive electrode plate at the positive electrode tail end is H2, and 0.6≤H1 / H2≤0.95.

[0021] In one or more of the above optional embodiments, H1 / H2≥0.6, which is conducive to effectively alleviating the stress concentration in the gap position on one side of the negative electrode tail section close to the positive electrode winding tail end, thereby alleviating the problem of the electrode assembly's circle layer sinking near the winding center; H1 / H2≤0.95, avoids the risk of the thickness of the insulating part exceeding the thickness of the positive electrode sheet in the production process and generating a new stress concentration point, thereby effectively improving the problem of the electrode assembly sinking, thereby reducing the risk of short-circuit failure caused by puncturing the isolation membrane due to the sinking of the electrode assembly during a drop mechanical test or when the battery cell is in a drop condition, thereby improving the yield of the battery cell and the safety performance of the battery cell.

[0022] In some embodiments of the first aspect of the present application, 0.7≤H1 / H2≤0.85.

[0023] In one or more of the above optional embodiments, H1 / H2≥0.7, which is further conducive to effectively alleviating the stress concentration in the gap position on one side of the negative electrode tail section close to the positive electrode winding tail end, thereby further alleviating the problem of the electrode assembly's circle layer sinking near the winding center; H1 / H2≤0.85, further avoiding the risk of the thickness of the insulating part exceeding the thickness of the positive electrode sheet in the production process to generate a new stress concentration point, thereby effectively improving the problem of electrode assembly sinking, thereby reducing the risk of short-circuit failure caused by puncturing the isolation membrane due to the sinking of the electrode assembly during a drop mechanical test or when the battery cell is in a drop condition, thereby improving the yield of the battery cell and the safety performance of the battery cell.

[0024] In some embodiments of the first aspect of the present application, the positive electrode plate includes a negative electrode collector and a negative electrode active material layer, and the negative electrode active material layer is provided on at least one side of the negative electrode collector along the thickness direction of the negative electrode plate; along the extension direction of the winding axis of the electrode assembly, the size of the insulating part is smaller than the size of the negative electrode active material layer.

[0025] In one or more of the above optional embodiments, along the extension direction of the winding axis of the electrode assembly, the size of the insulating member is smaller than the size of the negative electrode active material layer, which can reduce the risk of interference between the insulating member and the negative electrode tab and worsening wetting, and can also avoid the loss of battery cell energy density due to the insulating member being too large in the extension direction of the winding axis of the electrode assembly.

[0026] In some embodiments of the first aspect of the present application, along the extension direction of the winding axis, the negative electrode active material layer exceeds one end of the insulating member, and along the opposite direction of the extension direction of the winding axis, the negative electrode active material layer exceeds the other end of the insulating member.

[0027] In one or more of the above optional embodiments, along the extension direction of the winding axis, the negative electrode active material layer exceeds one end of the insulating member, and along the opposite direction of the extension direction of the winding axis, the negative electrode active material layer exceeds the other end of the insulating member. This not only prevents the insulating member and the negative electrode tab from interfering with each other in the extension direction of the winding axis of the electrode assembly, but also prevents the insulating member from increasing the size of the electrode assembly in the extension direction of the winding axis of the electrode assembly, thereby causing a loss in the energy density of the battery cell.

[0028] In some embodiments of the first aspect of the present application, along the extension direction of the winding axis, the size of the insulating member is W1, the size of the negative electrode active material layer is W2, and 0.8≤W1 / W2≤0.95.

[0029] In one or more of the above optional embodiments, W1 / W2≥0.8, which can effectively alleviate the stress concentration in the gap position on one side of the negative electrode tail section close to the positive electrode winding tail end; W1 / W2≤0.95 can reduce the risk of interference between the insulating parts and the positive electrode ears and worsening wetting, and can also avoid the insulating parts increasing the size of the electrode assembly in the extension direction of the winding axis of the electrode assembly, thereby causing loss of battery cell energy density.

[0030] In some embodiments of the first aspect of the present application, along the thickness direction of the electrode assembly, the negative electrode tailing section is located outside the positive electrode tailing end.

[0031] In one or more of the above optional embodiments, the negative electrode tail section is located outside the positive electrode tail end, which is beneficial for the battery cell to have a higher energy density.

[0032] In some embodiments of the first aspect of the present application, the insulating member is connected to the inner surface of the negative electrode tail section.

[0033] In one or more of the above optional embodiments, the negative electrode tailing section is located on the outside of the positive electrode tailing end, and the insulating part is connected to the inner surface of the negative electrode tailing section, which is convenient for the installation of the insulating part and can also reduce the relative movement of the insulating part and the positive electrode tailing end after the electrode assembly expands, so that the insulating part can always increase the uniformity of the force acting on the outer shell when the electrode assembly expands, reduce the risk of the electrode assembly being sunken due to the force of the outer shell, and reduce the risk of failure due to puncturing the diaphragm due to the sunken electrode assembly during the drop mechanical test and when the battery cell is in a drop condition, thereby improving the yield of the battery cell and the safety performance of the battery cell.

[0034] In some embodiments of the first aspect of the present application, the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is provided on at least one side of the negative electrode current collector along the thickness direction of the negative electrode plate; the material of the negative electrode active material layer includes silicon element, and in the negative electrode active material layer, the weight percentage of the silicon element is G, 0.5%≤G≤10%.

[0035] In one or more of the above optional embodiments, G≥0.5%, so that the battery cell has a higher energy density, and G≤10%, which is beneficial to further control the cost and expansion of the battery cell.

[0036] In some embodiments of the first aspect of the present application, G≥2%.

[0037] In some embodiments of the first aspect of the present application, along the winding direction, the length of the negative electrode tail section is L3, 3mm≤L3≤10mm.

[0038] In one or more of the above optional embodiments, L3≥3 mm, so that the length of the negative electrode tail section is large enough to reduce the risk of lithium plating, and L3≤10 mm to reduce the waste of active materials.

[0039] In some embodiments of the first aspect of the present application, 5mm≤L3≤8mm.

[0040] In one or more of the above optional embodiments, L3≥5mm, so that the length of the negative electrode tail section is longer, which can further reduce the risk of lithium plating, and L3≤8mm, further reducing the waste of active materials.

[0041] In some embodiments of the first aspect of the present application, the insulating member includes adhesive tape or an insulating coating.

[0042] In one or more of the above optional embodiments, the insulating member includes adhesive tape. The adhesive tape has low cost, good bonding performance, and is convenient to be set in the battery cell. The adhesive tape is soft and convenient to be wound together with the positive electrode sheet, the negative electrode sheet and the isolation film. The risk of warping of the adhesive tape is low.

[0043] In some embodiments of the first aspect of the present application, the battery cell is a cylindrical battery cell.

[0044] In one or more of the above optional embodiments, the battery cell is a cylindrical battery cell, and an insulating member is arranged on one side of the negative electrode tail section of the cylindrical battery cell close to the positive electrode tail end, and the insulating member and the positive electrode sheet are arranged along the winding direction, thereby improving the uniformity of the force acting on the outer shell when the electrode assembly expands, reducing the risk of the electrode assembly being sunken due to the force of the outer shell, or alleviating the degree of the electrode assembly being sunken due to the action of the outer shell after expansion, thereby reducing the risk of short-circuit failure caused by puncturing the isolation membrane due to the sunken electrode assembly during a drop mechanical test or when the battery cell is in a drop condition, thereby improving the yield of the battery cell and the safety performance of the battery cell.

[0045] In a second aspect, an embodiment of the present application provides an electrical device, comprising a battery cell provided by any of the above embodiments.

[0046] In one or more of the above optional embodiments, the battery cell provided in any of the above embodiments has better safety, and the electrical equipment powered by the battery cell has better electrical safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 An exploded diagram of a battery cell provided in some embodiments of the present application;

[0049] Figure 2 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0050] Figure 3 for Figure 2 Sectional view at A1 in the middle;

[0051] Figure 4 A schematic diagram of a positive electrode sheet and a negative electrode sheet after unfolding is provided for some embodiments of the present application;

[0052] Figure 5 A schematic diagram of the negative electrode plate and the insulating member after being matched together provided in some embodiments of the present application.

[0053] Icon: 100-battery cell; 10-casing; 11-shell; 12-cover; 20-electrode assembly; 21-positive electrode sheet; 211-positive current collector; 212-positive active material layer; 213-positive electrode tail end; 214-positive electrode starting end; 22-negative electrode sheet; 221-negative current collector; 222-negative active material layer; 223-negative electrode tail section; 224-negative electrode tail end; 225-negative electrode ear; 23-separation film; 30-insulating member; X-winding direction; X'-length direction of the positive electrode sheet; Y-width direction of the positive electrode sheet; Z-thickness direction of the positive electrode sheet. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0056] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0057] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0058] In the description of the embodiments of the present application, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, or the orientation or positional relationship commonly understood by those skilled in the art, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0059] In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0060] At present, judging from the development of the market situation, the application of battery cells is becoming more and more extensive. Battery cells are widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as electric tools, drones, energy storage equipment and other fields. With the continuous expansion of the application field of battery cells, the market demand is also constantly expanding, and the requirements for battery cell safety are becoming higher and higher.

[0061] The electrode assembly of the battery cell includes a positive electrode sheet and a negative electrode sheet. Along the winding direction of the electrode assembly, the negative electrode sheet extends beyond the positive electrode winding tail end. The size of the electrode assembly at the position corresponding to the positive electrode tail end is larger, and the position of the electrode assembly at the positive electrode tail end is closer to the inner wall of the shell than other positions. After the electrode assembly expands, the position of the electrode assembly corresponding to the positive electrode tail end first abuts against the inner wall of the shell, and the shell exerts a force on the position of the electrode assembly corresponding to the positive electrode tail end, and stress concentration is generated in the electrode assembly at the position corresponding to the positive electrode tail end, which causes serious inward collapse of the circle layer of the electrode assembly near the winding center after the electrode assembly expands, thereby puncturing the isolation membrane due to the inward collapse of the circle layer of the electrode assembly near the winding center, thereby causing short-circuit failure, reducing the safety performance of the battery cell.

[0062] Based on the above considerations, in order to alleviate the problem that the stress concentration at the position corresponding to the positive electrode tail end of the electrode assembly causes the electrode assembly to sink inward near the winding center, thereby causing the battery cell to have lower safety performance, the embodiment of the present application provides a battery cell, the battery cell includes an electrode assembly and an insulating member; the electrode assembly is a winding structure, the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separation film, the separation film insulates and isolates the positive electrode sheet from the negative electrode sheet, along the winding direction of the electrode assembly, the positive electrode sheet has a positive electrode tail end, and the negative electrode sheet has a negative electrode tail section that exceeds the positive electrode tail end; the insulating member is arranged on the side of the negative electrode tail section close to the positive electrode tail end, and the insulating member 30 and the positive electrode sheet are arranged along the winding direction.

[0063] An insulating member is provided on one side of the negative electrode tail section near the positive electrode tail end, and the insulating member and the positive electrode sheet are arranged along the winding direction, that is, the insulating member fills the space between the positive electrode tail end and the negative electrode tail end of the negative electrode sheet, and fills the gap on one side of the negative electrode tail section near the positive electrode tail end, which improves the uniformity of the force acting on the outer shell when the electrode assembly expands, reduces the risk of the electrode assembly near the winding center being sunken after the electrode assembly expands at the corresponding position of the positive electrode tail end, or alleviates the degree of the electrode assembly near the winding center being sunken after the electrode assembly expands at the corresponding position of the positive electrode tail end, thereby reducing the risk of the separator being punctured due to the sunken layer of the electrode assembly near the winding center in the drop mechanical test or the battery cell being in a drop condition, thereby improving the yield of the battery cell and the safety performance of the battery cell. In addition, by providing the insulating member, the stress at the contact position between the negative electrode tail section and the positive electrode tail end can also be released, reducing the risk of the outermost circle of the negative electrode being broken.

[0064] The battery cell disclosed in the embodiment of the present application can be used in, but not limited to, electric two-wheeled vehicles, electric tools, drones, energy storage devices and other electrical equipment. The battery cell with the working condition of the present application can also be used as a power supply system for electrical equipment, which is conducive to improving the safety performance of the battery cell.

[0065] The present application provides an electric device using a battery cell as a power source, and the electric device may be, but is not limited to, electronic equipment, electric tools, electric vehicles, drones, and energy storage devices. Among them, electronic equipment may include mobile phones, tablets, laptops, etc., electric tools may include electric drills, electric saws, etc., and electric vehicles may include electric cars, electric motorcycles, electric bicycles, etc.

[0066] like Figure 1 , Figure 2 As shown, an embodiment of the present application provides a battery cell 100 , which includes a housing 10 and an electrode assembly 20 ; the electrode assembly 20 is accommodated in the housing 10 .

[0067] The housing 10 forms a storage space. The storage space can be used to store the electrode assembly 20, electrolyte, etc. The housing 10 can be a hard shell 11, for example, the housing 10 is a steel shell or an aluminum shell, forming a steel shell battery cell or an aluminum shell battery cell. The housing 10 can also be formed of a softer material, for example, the housing 10 is an aluminum plastic film or a steel plastic film, forming a soft package battery cell.

[0068] The housing 10 may include a shell 11 and a cover 12 . The shell 11 has an opening at at least one end. The cover 12 is used to cover the opening of the shell 11 , so that the shell 11 and the cover 12 together define a receiving space.

[0069] The electrode assembly 20 includes a positive electrode sheet 21 , a negative electrode sheet 22 and a separator 23 .

[0070] The positive electrode sheet 21 includes a positive current collector 211 and a positive active material layer 212. The positive active material layer 212 is provided on at least one side of the positive current collector 211. For lithium-ion batteries, the material of the positive current collector 211 can be aluminum. The positive active material layer 212 can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide. The positive current collector 211 can be a composite current collector or a non-composite current collector.

[0071] The negative electrode sheet 22 includes a negative electrode current collector 221 and a negative electrode active material layer 222. The negative electrode active material layer 222 is disposed on at least one side of the negative electrode current collector 221. For lithium-ion batteries, the material of the negative electrode current collector 221 can be copper. The negative electrode current collector 221 can be a composite current collector or a non-composite current collector. The negative electrode active material can be a carbon material or a silicon material, etc.

[0072] In some embodiments, the material of the negative electrode active material layer 222 includes silicon. In the negative electrode active material layer 222 , the weight percentage of silicon is G, and 0.5%≤G≤10%.

[0073] By way of example, G may be 0.5%, 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0074] G≥0.5%, so that the battery cell 100 has a higher energy density, and G≤10%, which is beneficial to further control the cost of the battery cell 100 and the expansion degree of the battery cell.

[0075] Further, G≥2%. For example, G may be 2%, 2.5%, 3.5%, 4.5%, 5.5%, 6.5%, 7.5%, 8.5%, 9.5%, 9.9%, etc.

[0076] The weight percentage G of the silicon element can be measured as follows: discharge the battery cell at 0.5C to 2.5V, then disassemble the battery cell, take 12 small discs at the geometric center of the negative electrode plate 22, where the radius of the small disc is 7mm, and use ICP equipment to measure the Si element content. In view of equipment differences and interference from factors such as electrolyte, the final measurement value is the average weight percentage of the Si element in the 12 small discs.

[0077] The separator 23 insulates and separates the positive electrode sheet 21 and the negative electrode sheet 22 to reduce the risk of short circuit of the battery cell 100. The material of the separator 23 may include PP (polypropylene) or PE (polyethylene).

[0078] The electrode assembly 20 is a wound structure. The positive electrode sheet 21, the separator 23, the negative electrode sheet 22 and another separator 23 are stacked in a certain order and then wound to form an electrode assembly with a wound structure; or, the separator 23, the positive electrode sheet 21, another separator 23 and the negative electrode sheet 22 are stacked in a certain order and then wound to form an electrode assembly with a wound structure. The wound electrode assembly 20 can be a flat wound electrode assembly 20 or a cylindrical electrode assembly 20. In the embodiment where the electrode assembly 20 is a cylindrical structure, the battery cell 100 can be a cylindrical battery cell or a cylindrical battery cell. Figure 1 FIG. 4 shows a case where the battery cell 100 is a cylindrical battery cell. Figure 2 , the electrode assembly 20 is shown as a cylindrical structure.

[0079] The positive electrode sheet 21 has a positive electrode tail end 213, and the positive electrode tail end 213 of the positive electrode sheet 21 is the end of the positive electrode sheet 21 that is farthest from the winding center of the electrode assembly 20 along the winding direction X of the electrode assembly 20. Along the winding direction X of the electrode assembly 20, one end of the positive electrode sheet 21 and the positive electrode tail end 213 is the positive electrode starting end 214. The negative electrode sheet 22 exceeds the positive electrode tail end 213 along the winding direction X of the electrode assembly 20, reducing the risk of lithium deposition in the battery cell 100. Specifically, the negative electrode sheet 22 has a negative electrode tail section 223 that exceeds the positive electrode tail end 213. Among them, along the thickness direction Z of the positive electrode sheet, the negative electrode tail section 223 can be located outside the positive electrode tail end 213. Along the thickness direction Z of the positive electrode sheet, the negative electrode tail section 223 is located outside the positive electrode tail end 213, which is beneficial to improve the energy density of the battery cell 100. Of course, in another embodiment, along the thickness direction Z of the positive electrode sheet, the negative electrode tailing section 223 is located inside the positive electrode tailing end 213 . Figure 2 2 shows the situation in which the negative electrode tailing section 223 is located outside the positive electrode tailing end 213 along the thickness direction Z of the positive electrode sheet.

[0080] like Figure 3 , Figure 4 As shown, in some embodiments, along the winding direction X, the length of the negative electrode tailing segment 223 is L3, 3mm≤L3≤10mm.

[0081] L3 is the minimum distance between the negative electrode tail end 224 and the positive electrode tail end 213 along the winding direction X.

[0082] Exemplarily, L3 can be 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, etc.

[0083] L3≥3mm, so that the length of the negative electrode tail section 223 is large enough to reduce the risk of lithium deposition, and L3≤10mm, reducing the waste of active materials.

[0084] Furthermore, 5mm≤L3≤8mm.

[0085] Exemplarily, L3 can be 5mm, 5.2mm, 5.4mm, 5.6mm, 5.8mm, 6.2mm, 6.4mm, 6.6mm, 6.8mm, 7.2mm, 7.4mm, 7.6mm, 7.8mm, 7.9mm, 8mm, etc.

[0086] L3≥3mm, so that the length of the negative electrode tail section 223 is larger, which can further reduce the risk of lithium plating; L3≤8mm, further reducing the waste of active materials.

[0087] like Figure 3 , Figure 4 As shown, in some embodiments, the battery cell 100 further includes an insulating member 30, which is disposed on one side of the negative electrode tail section 223 close to the positive electrode tail end 213, and the insulating member 30 and the positive electrode sheet 21 are arranged along the winding direction X.

[0088] When the positive electrode sheet 21 and the negative electrode sheet 22 are in the unfolded state, the length direction of the negative electrode sheet 22 is parallel to the length direction of the positive electrode sheet 21, the length direction of the positive electrode sheet 21 corresponds to the winding direction X of the electrode assembly 20, the width direction of the negative electrode sheet 22 is parallel to the width direction Y of the positive electrode sheet, and the width direction Y of the positive electrode sheet corresponds to the extension direction of the winding axis of the electrode assembly 20. When the positive electrode sheet 21 and the negative electrode sheet 22 are in the unfolded state, the length direction of the positive electrode sheet 21, the width direction Y of the positive electrode sheet, and the thickness direction Z of the positive electrode sheet are perpendicular to each other, and the length direction of the negative electrode sheet 22, the width direction of the negative electrode sheet 22, and the thickness direction of the negative electrode sheet 22 are perpendicular to each other.

[0089] The insulating member 30 may be connected to the negative electrode tailing section 223, for example, the insulating member 30 is bonded to the negative electrode tailing section 223. In the embodiment where the negative electrode tailing section 223 is located outside the positive electrode tailing end 213 along the thickness direction Z of the positive electrode sheet, the insulating member 30 may be connected to the inner surface of the negative electrode tailing section 223, so that the insulating member 30 is disposed on the side of the negative electrode tailing section 223 close to the positive electrode tailing end 213. The negative electrode tail section 223 is located on the outside of the positive electrode tail end 213, and the insulating member 30 is connected to the inner surface of the negative electrode tail section 223, which is convenient for the installation of the insulating member 30 and can also reduce the relative movement of the insulating member 30 and the positive electrode tail end 213 after the electrode assembly 20 expands, so that the insulating member 30 can always increase the uniformity of the force acting on the outer shell 10 when the electrode assembly 20 expands, reduce the risk of the electrode assembly 20 being sunken due to the force of the outer shell 10, and reduce the risk of failure caused by puncturing the diaphragm due to the sunken electrode assembly 20 during the drop mechanical test and when the battery cell 100 is in a drop condition, thereby improving the yield of the battery cell 100 and the safety performance of the battery cell 100.

[0090] In an embodiment where the negative electrode tailing segment 223 is located on the inner side of the positive electrode tailing end 213 along the thickness direction Z of the positive electrode plate, the insulating member 30 can be connected to the outer surface of the negative electrode tailing segment 223 so that the insulating member 30 is arranged on the side of the negative electrode tailing segment 223 close to the positive electrode tailing end 213. The negative electrode tailing section 223 is located on the inner side of the positive electrode tailing end 213, and the insulating member 30 is connected to the outer surface of the negative electrode tailing section 223, which is convenient for the installation of the insulating member 30 and can also reduce the relative movement of the insulating member 30 and the positive electrode tailing end 213 after the electrode assembly 20 expands, so that the insulating member 30 can always increase the uniformity of the force acting on the outer shell 10 when the electrode assembly 20 expands, reduce the risk of the electrode assembly 20 being sunken due to the force of the outer shell 10, and reduce the risk of failure caused by puncturing the diaphragm due to the sunken electrode assembly 20 during the drop mechanical test and when the battery cell 100 is in a drop condition, thereby improving the yield of the battery cell 100 and the safety performance of the battery cell 100.

[0091] The inner surface and outer surface of the negative electrode finishing segment 223 are respectively two opposite surfaces of the negative electrode finishing segment 223 in the thickness direction of the negative electrode pole sheet 22, wherein the inner surface of the negative electrode finishing segment 223 is the surface of the negative electrode finishing segment 223 close to the winding axis in the thickness direction of the negative electrode pole sheet 22, and the outer surface of the negative electrode finishing segment 223 is the surface of the negative electrode finishing segment 223 away from the winding axis in the thickness direction of the negative electrode pole sheet 22.

[0092] In other embodiments, the insulating member 30 may be disposed on the separator 23 on a side of the negative electrode tailing section 223 close to the positive electrode tailing end 213 .

[0093] The insulating member 30 and the positive electrode sheet 21 are arranged along the winding direction X, and there is no overlapping portion between the insulating member 30 and the positive electrode sheet 21 in the area corresponding to the positive electrode tail end 213 .

[0094] An insulating member 30 is provided on one side of the negative electrode tail section 223 close to the positive electrode tail end 213, and the insulating member 30 and the positive electrode sheet 21 are arranged along the winding direction X, that is, the insulating member 30 fills the space between the positive electrode tail end 213 and the negative electrode tail end 224 of the negative electrode sheet 22, and fills the gap on one side of the negative electrode tail section 223 close to the positive electrode tail end 213, thereby improving the uniformity of the force acting on the outer shell 10 when the electrode assembly 20 expands, and reducing the pressure exerted by the outer shell 10 on the corresponding position of the positive electrode tail end 213 after the electrode assembly 20 expands. 0, or alleviates the degree to which the circle layer of the electrode assembly 20 near the winding center sinks in after the electrode assembly 20 expands and is acted upon by the outer shell 10 at the corresponding position of the positive electrode tail end 213, thereby reducing the risk of short-circuit failure caused by puncturing the isolation membrane 23 due to the sinking of the circle layer of the electrode assembly 20 near the winding center during a drop mechanical test or when the battery cell 100 is in a drop condition, thereby improving the yield of the battery cell 100 and the safety performance of the battery cell 100.

[0095] In an embodiment where the battery cell 100 is a cylindrical battery cell 100, an insulating member 30 is provided on one side of the negative electrode tail section 223 of the cylindrical battery cell 100 close to the positive electrode tail end 213, and the insulating member 30 and the positive electrode sheet 21 are arranged along the winding direction X, thereby improving the uniformity of the force acting on the outer shell 10 when the electrode assembly 20 expands, reducing the risk of the electrode assembly 20 being sunken due to the force of the outer shell 10, or alleviating the degree of the electrode assembly 20 being sunken due to the action of the outer shell 10 after expansion, thereby reducing the risk of short-circuit failure caused by puncturing the isolation membrane 23 due to the sunken electrode assembly 20 during a drop mechanical test or when the battery cell 100 is in a drop condition, thereby improving the yield of the battery cell 100 and the safety performance of the battery cell 100.

[0096] The drop mechanical test of the battery cell 100 may be performed in the following manner:

[0097] After the lithium-ion battery cells of each embodiment (battery cell 100 provided with insulating member 30) and the comparative example (battery cell 100 without insulating member 30) are charged to 4.2V at 2C constant current, they are charged to 0.05C at constant voltage to reach a fully charged state. Place the fully charged lithium-ion battery cell on the test table, and place a round rod with a diameter of φ15.8±0.1mm and a length of at least 6cm at the center of the wide surface of the lithium-ion battery cell. Wait for the longitudinal axis of the lithium-ion battery cell to be parallel to the surface of the test table and perpendicular to the longitudinal axis of the round rod. Use a 9.1kg heavy hammer to drop vertically and freely from a height of 610mm, and drop it at the intersection of the round rod and the lithium-ion battery.

[0098] Judgment standard: If there is no fire or explosion, the drop mechanical test has passed.

[0099] Twenty lithium-ion cells were tested for each embodiment or comparative example, and the qualified rate of the drop mechanical test = the number of passed cells / 20.

[0100] The degree of indentation of the coil layer of the electrode assembly 20 of the battery cell 100 close to the winding axis can be tested as follows:

[0101] The lithium-ion cells in each embodiment (cell 100 with insulating member 30) and the comparative example (cell 100 without insulating member 30) were subjected to charge and discharge cycle test in a 25°C constant temperature box, with a charge and discharge voltage range of 2.5V to 4.2V, charged to 4.2V at 2C constant current, then charged to 0.05C at 4.2V constant voltage and left to stand for 5 minutes, and then discharged to 2.5V at 6C constant current, and the above charge and discharge process was repeated for 600 cycles. After the cell 100 was fully charged, a CT scan was performed to measure the degree of indentation. Among them, the degree of indentation is: in the indentation area, the distance between the most protruding position of the innermost circle of the electrode assembly 20 in the direction close to the winding center and the circle layer closest to the winding axis without indentation is measured 5 times and the average value is taken.

[0102] The insulating member 30 may be made of a variety of materials, for example, the insulating member 30 is a ceramic coating, a rubber coating, etc. In some embodiments, the insulating member 30 includes adhesive tape. The adhesive tape has low cost, good bonding performance, and is convenient to be set in the battery cell 100. The adhesive tape is soft and convenient to be wound together with the positive electrode sheet, the negative electrode sheet, and the separator 23, and the risk of warping of the adhesive tape is low.

[0103] like Figure 3 , Figure 4 As shown, in some embodiments, along the winding direction X, the positive electrode sheet 21 and the insulating member 30 are spaced apart.

[0104] It can be understood that, along the winding direction X, the positive electrode tail end 213 and the insulating member 30 are spaced apart. Along the winding direction X, there is a distance between the positive electrode tail end 213 and the insulating member 30 .

[0105] Along the winding direction X, the positive electrode sheet 21 and the insulating member 30 are spaced apart, which is beneficial to reducing the risk of overlapping between the insulating member 30 and the positive electrode tail section during the manufacturing process, thereby reducing the risk of stress concentration caused by the overlap between the insulating member 30 and the positive electrode tail section during the manufacturing process, and worsening the risk of the electrode assembly 20 being sunken in near the winding center, thereby reducing the risk of puncturing the isolation membrane 23 and causing short-circuit failure due to the sunken circle of the electrode assembly 20 near the winding center during a drop mechanical test or when the battery cell 100 is in a drop condition, thereby improving the yield of the battery cell 100 and the safety performance of the battery cell 100.

[0106] like Figure 3 , Figure 4 As shown, in some embodiments, along the winding direction X, the distance between the positive electrode tail end 213 and the insulating member 30 is L1, and 0.1 mm≤L1≤0.8 mm.

[0107] Illustratively, L1 may be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, etc.

[0108] 0.1mm≤L1 is conducive to reducing the risk of overlapping of the insulating member 30 and the positive electrode tail section during the manufacturing process, thereby reducing the risk of stress concentration due to the overlap of the insulating member 30 and the positive electrode tail section during the manufacturing process, and worsening the risk of the electrode assembly 20 near the winding center being sunken. L1≤0.8mm, the spacing between the insulating member 30 and the positive electrode tail end 213 in the winding direction X is controlled within a reasonable range, thereby effectively alleviating the stress concentration of the negative electrode sheet 22 at the corresponding position of the positive electrode tail end 213, and further effectively alleviating the problem of the electrode assembly 20 near the winding. The problem of the sunken layer of the electrode assembly 20 is reduced, thereby reducing the risk of puncturing the separator 23 due to the sunken layer of the electrode assembly 20 near the winding, and improving the yield and safety performance of the battery cell 100.

[0109] Furthermore, 0.2mm≤L1≤0.6mm.

[0110] Illustratively, L1 may be 0.2 mm, 0.23 mm, 0.26 mm, 0.28 mm, 0.32 mm, 0.36 mm, 0.38 mm, 0.42 mm, 0.46 mm, 0.48 mm, 0.52 mm, 0.56 mm, 0.58 mm, 0.6 mm, etc.

[0111] L1≥0.2mm is conducive to further reducing the risk of overlapping of the insulating member 30 and the positive electrode tail section during the manufacturing process, thereby further reducing the risk of stress concentration due to the overlap of the insulating member 30 and the positive electrode tail section during the manufacturing process, and worsening the risk of the electrode assembly 20 near the winding center being sunken. L1≤0.6mm, the spacing between the insulating member 30 and the positive electrode tail end 213 in the winding direction X is controlled within a reasonable range, thereby further effectively alleviating the stress concentration of the negative electrode sheet 22 at the corresponding position of the positive electrode tail end 213, and further effectively alleviating the problem of the electrode assembly 20 near the winding. The problem of the sunken layer, thereby further reducing the risk of puncturing the separator 23 due to the sunken layer of the electrode assembly 20 near the winding, improves the yield and safety performance of the battery cell 100.

[0112] like Figure 3 , Figure 3As shown, in some embodiments, along the winding direction X, the negative electrode tailing segment 223 extends beyond an end of the insulating member 30 away from the positive electrode tailing end 213 .

[0113] Along the winding direction X, the size of the negative electrode end segment 223 is smaller than the size of the insulating member 30. Along the winding direction X, the end of the insulating member 30 close to the positive electrode end 213 can be flush with the end of the negative electrode end segment 223 closest to the positive electrode end 213. Along the opposite direction of the winding direction X, the negative electrode end segment 223 can exceed the end of the insulating member 30 closest to the positive electrode end 213.

[0114] Along the winding direction X, the negative electrode end section 223 exceeds the end of the insulating member 30 away from the positive electrode end end 213, so that the insulating member 30 is located in the space between the positive electrode end end 213 and the negative electrode end end 224 of the negative electrode sheet 22, and fills in the gap on one side of the negative electrode end section 223 close to the positive electrode end end 213, thereby alleviating the stress concentration at the gap position on one side of the negative electrode end section 223 close to the positive electrode winding end end, thereby facilitating the problem of the electrode assembly 20 being sunken in the coil near the winding center, reducing the risk of the separator 23 being punctured due to the sunken coil of the electrode assembly 20 near the winding, and improving the yield and safety performance of the battery cell 100. Along the winding direction X, the negative electrode end section 223 exceeds the end of the insulating member 30 away from the positive electrode end end 213, and also avoids the insulating member 30 occupying extra space inside the battery cell 100 and losing energy density.

[0115] Of course, in other embodiments, along the winding direction X, the end of the negative electrode tailing segment 223 away from the positive electrode tailing end 213 may be flush with the positive electrode tailing end 213 .

[0116] like Figure 3 , Figure 4 As shown, in some embodiments, along the winding direction X, the length of the insulating member 30 is L2, the length of the negative electrode tailing segment 223 is L3, and 0.6≤L2 / L3≤0.95.

[0117] For example, L2 / L3 can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, etc.

[0118] L2 / L3≥0.6, effectively alleviates the stress concentration of the negative electrode sheet 22 at the corresponding position of the positive electrode tail end 213, thereby effectively alleviating the problem of the electrode assembly 20 being sunken in the coil near the winding center. L2 / L3≤0.95 is conducive to reducing the risk of the insulating member 30 overlapping with the positive electrode tail section during the manufacturing process, thereby further reducing the risk of stress concentration due to the overlap of the insulating member 30 with the positive electrode tail section during the manufacturing process, and worsening the risk of the electrode assembly 20 being sunken in the coil near the winding center.

[0119] Furthermore, 0.7≤L2 / L3≤0.85.

[0120] For example, L2 / L3 can be 0.7, 0.71, 0.72, 0.73, 0.74, 0.76, 0.77, 0.78, 0.79, 0.81, 0.82, 0.83, 0.84, 0.85, etc.

[0121] L2 / L3≥0.7, further effectively alleviates the stress concentration of the negative electrode sheet 22 at the corresponding position of the positive electrode tail end 213, thereby effectively alleviating the problem of the electrode assembly 20 being sunken in the coil near the winding center. L2 / L3≤0.85 is conducive to further reducing the risk of the insulating member 30 overlapping with the positive electrode tail section during the manufacturing process, thereby further reducing the risk of stress concentration due to the overlap of the insulating member 30 with the positive electrode tail section during the manufacturing process, and worsening the risk of the electrode assembly 20 being sunken in the coil near the winding center.

[0122] The thickness of the insulating member 30 may be less than, equal to, or greater than the thickness of the positive electrode sheet 21 at the positive electrode winding end.

[0123] like Figure 3 , Figure 4 As shown, in some embodiments, the thickness of the insulating member 30 is less than the thickness of the positive electrode sheet 21 at the positive electrode tail end 213 .

[0124] In the embodiment where the negative electrode tail section 223 is located on the outside of the positive electrode tail end 213 along the thickness direction Z of the positive electrode plate, the positive electrode collector 211 may be provided with active material layers on both sides of its thickness direction, and the thickness of the positive electrode plate 21 at the positive electrode tail end 213 is the sum of the thickness of the positive electrode collector 211 and the thickness of the two positive electrode active material layers 212.

[0125] In the embodiment where the negative electrode tail section 223 is located on the inner side of the positive electrode tail end 213 along the thickness direction Z of the positive electrode sheet, the positive electrode current collector 211 of the positive electrode sheet 21 at the positive electrode tail end 213 may be provided with a positive electrode active material layer 212 only on one side facing the winding axis, then the thickness of the positive electrode sheet 21 at the positive electrode tail end 213 is the sum of the thickness of the positive electrode current collector 211 and the thickness of one positive electrode active material layer 212.

[0126] like Figure 3 , Figure 4 As shown, the thickness of the insulating member 30 is H1, and the thickness of the positive electrode sheet 21 at the positive electrode tail end 213 is H2, and H1<H2.

[0127] The thickness of the insulating part 30 is smaller than the thickness of the positive electrode sheet 21 at the positive electrode tail end 213, which is beneficial to alleviate the stress concentration in the gap position of the negative electrode sheet 22 on one side near the positive electrode tail end 213, and the insulating part 30 will not generate a new stress concentration point, which effectively improves the problem of the circle collapse of the electrode assembly 20 near the winding center, thereby reducing the risk of short-circuit failure caused by puncturing the isolation membrane 23 due to the collapse of the circle of the electrode assembly 20 near the winding center during a drop mechanical test or when the battery cell 100 is in a drop condition, thereby improving the yield of the battery cell 100 and the safety performance of the battery cell 100.

[0128] like Figure 3 , Figure 4 As shown, in some embodiments, the thickness of the insulating member 30 is H1, the thickness of the positive electrode plate 21 at the positive electrode tail end 213 is H2, and 0.6≤H1 / H2≤0.95.

[0129] Illustratively, H1 / H2 may be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, etc.

[0130] H1 / H2≥0.6 is conducive to effectively alleviating the stress concentration at the gap position on one side of the negative electrode tail section 223 close to the positive electrode winding tail end, thereby alleviating the problem of the electrode assembly 20 being sunken in near the winding center; H1 / H2≤0.95 avoids the risk of the thickness of the insulating part 30 exceeding the thickness of the positive electrode plate 21 during the production process to generate a new stress concentration point, thereby effectively improving the problem of the electrode assembly 20 being sunken in, thereby reducing the risk of the isolation membrane 23 being punctured due to the sunken electrode assembly 20 during the drop mechanical test or when the battery cell 100 is in a drop condition, thereby improving the yield of the battery cell 100 and the safety performance of the battery cell 100.

[0131] Further, 0.7≤H1 / H2≤0.85.

[0132] Illustratively, H1 / H2 may be 0.7, 0.71, 0.72, 0.73, 0.74, 0.76, 0.77, 0.78, 0.79, 0.81, 0.82, 0.83, 0.84, 0.85, etc.

[0133] H1 / H2≥0.7, which is further conducive to effectively alleviating the stress concentration in the gap position on one side of the negative electrode tail section 223 close to the positive electrode winding tail end, thereby further alleviating the problem of the electrode assembly 20 being sunken in near the winding center; H1 / H2≤0.85, further avoiding the risk of the thickness of the insulating part 30 exceeding the thickness of the positive electrode plate 21 in the production process and generating a new stress concentration point, thereby effectively improving the problem of the electrode assembly 20 being sunken in, thereby reducing the risk of the isolation membrane 23 being punctured due to the sunken electrode assembly 20 during the drop mechanical test or when the battery cell 100 is in a drop condition, thereby causing a short circuit failure, thereby improving the yield of the battery cell 100 and the safety performance of the battery cell 100.

[0134] like Figure 5 As shown, in some embodiments, along the extension direction of the winding axis of the electrode assembly 20 , the size of the insulating member 30 is smaller than the size of the negative electrode active material layer 222 .

[0135] After the positive electrode sheet 21 is unfolded, the extension direction of the winding axis of the electrode assembly 20 corresponds to the width direction of the negative electrode sheet 22 .

[0136] Along the extension direction of the winding axis of the electrode assembly 20, one end of the insulating member 30 may be flush with one end of the negative electrode active material layer 222, and the negative electrode active material layer 222 may extend beyond the other end of the insulating member 30. For example, along the extension direction of the winding axis of the electrode assembly 20, one end of the negative electrode active material layer 222 away from the negative electrode tab 225 is flush with one end of the insulating member 30 away from the negative electrode tab 225, and one end of the negative electrode active material layer 222 close to the negative electrode tab 225 is closer to the negative electrode tab 225 than one end of the insulating member 30 close to the negative electrode tab 225, that is, the negative electrode active material layer 222 extends beyond one end of the insulating member 30 close to the negative electrode tab 225.

[0137] Of course, along the extension direction of the winding axis of the electrode assembly 20 , the negative active material layer 222 may exceed opposite ends of the insulating member 30 .

[0138] Along the extension direction of the winding axis of the electrode assembly 20, the size of the insulating part 30 is smaller than the size of the negative electrode active material layer 222, which can reduce the risk of interference between the insulating part 30 and the negative electrode tab 225 and worsening wetting, and can also avoid the insulating part 30 being too large in the extension direction of the winding axis of the electrode assembly 20, resulting in a loss of energy density of the battery cell 100.

[0139] Please continue to refer to Figure 5 In some embodiments, the negative electrode active material layer 222 extends beyond one end of the insulating member 30 along the extension direction of the winding axis, and the negative electrode active material layer 222 extends beyond the other end of the insulating member 30 in the opposite direction of the extension direction of the winding axis.

[0140] It can be understood that, along the extension direction of the winding axis of the electrode assembly 20, the negative electrode active material layer 222 can exceed the opposite ends of the insulating member 30. In other words, in the extension direction of the winding axis of the electrode assembly 20, the end of the negative electrode active material layer 222 away from the negative electrode tab 225 is farther away from the negative electrode tab 225 than the end of the insulating member 30 away from the negative electrode tab 225, and the end of the negative electrode active material layer 222 close to the negative electrode tab 225 is closer to the negative electrode tab 225 than the end of the insulating member 30 close to the negative electrode tab 225.

[0141] Along the extension direction of the winding axis, the negative electrode active material layer 222 exceeds one end of the insulating member 30, and along the opposite direction of the extension direction of the winding axis, the negative electrode active material layer 222 exceeds the other end of the insulating member 30. This not only prevents the insulating member 30 and the negative electrode tab 225 from interfering with each other in the extension direction of the winding axis of the electrode assembly 20, but also prevents the insulating member 30 from increasing the size of the electrode assembly 20 in the extension direction of the winding axis of the electrode assembly 20, thereby causing a loss in energy density of the battery cell 100.

[0142] like Figure 5 As shown, in some embodiments, along the extension direction of the winding axis, the size of the insulating member 30 is W1, the size of the negative electrode active material layer 222 is W2, and 0.8≤W1 / W2≤0.95.

[0143] Illustratively, W1 / W2 may be 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, etc.

[0144] W1 / W2≥0.8, which can effectively alleviate the stress concentration in the gap position on one side of the negative electrode tail section 223 close to the positive electrode winding tail end; W1 / W2≤0.95, which can reduce the risk of interference between the insulating part 30 and the positive electrode ear and worsening wetting, and can also avoid the insulating part 30 increasing the size of the electrode assembly 20 in the extension direction of the winding axis of the electrode assembly 20, thereby causing energy density loss of the battery cell 100.

[0145] When it is necessary to explain, the measurement of any dimension in the embodiments of the present application, that is, the measurement of L1, L2, L3, H1, H2, W1, and W2, can be performed as follows:

[0146] After fully discharging the battery cell 100 to 2.5V at a discharge current of 0.2C, use a soft ruler with an accuracy of 0.1mm to measure the characteristic quantity, and measure 5 times to get the average value.

[0147] An embodiment of the present application further provides an electrical device, and the electrical device includes the battery cell 100 provided in any of the above embodiments.

[0148] The battery cell 100 provided in any of the above embodiments has good safety, and the electrical equipment powered by the battery cell 100 has good electrical safety.

[0149] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes.

Claims

1. A battery cell, characterized in that: include: An electrode assembly with a winding structure, the electrode assembly comprising a positive electrode sheet, a negative electrode sheet and a separator, the separator is used to insulate and separate the positive electrode sheet from the negative electrode sheet, along the winding direction of the electrode assembly, the positive electrode sheet has a positive electrode tail end, and the negative electrode sheet has a negative electrode tail section that exceeds the positive electrode tail end; The insulating member is arranged on one side of the negative electrode tail section close to the positive electrode tail end, and the insulating member and the positive electrode sheet are arranged along the winding direction.

2. The battery cell according to claim 1, characterized in that: Along the winding direction, the positive electrode sheet and the insulating member are spaced apart.

3. The battery cell according to claim 2, characterized in that: Along the winding direction, the distance between the positive electrode tail end and the insulating member is L1, 0.1mm≤L1≤0.8mm.

4. The battery cell according to claim 3, characterized in that: 0.2mm≤L1≤0.6mm.

5. The battery cell according to claim 1, characterized in that: Along the winding direction, the negative electrode tail section exceeds an end of the insulating member away from the positive electrode tail end.

6. The battery cell according to claim 1, characterized in that: Along the winding direction, the length of the insulating member is L2, the length of the negative electrode tail section is L3, and 0.6≤L2 / L3≤0.

95.

7. The battery cell according to claim 6, characterized in that: 0.7≤L2 / L3≤0.

85.

8. The battery cell according to claim 1, characterized in that: The thickness of the insulating member is smaller than the thickness of the positive electrode plate at the positive electrode tail end.

9. The battery cell according to claim 8, characterized in that: The thickness of the insulating member is H1, the thickness of the positive electrode plate at the positive electrode tail end is H2, and 0.6≤H1 / H2≤0.

95.

10. The battery cell according to claim 9, characterized in that: 0.7≤H1 / H2≤0.

85.

11. The battery cell according to claim 1, characterized in that: The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer, and along the thickness direction of the negative electrode plate, the negative electrode active material layer is disposed on at least one side of the negative electrode current collector; Along the extension direction of the winding axis of the electrode assembly, the size of the insulating member is smaller than the size of the negative electrode active material layer.

12. The battery cell according to claim 11, characterized in that: The negative electrode active material layer exceeds one end of the insulating member along the extension direction of the winding axis, and the negative electrode active material layer exceeds the other end of the insulating member along the opposite direction of the extension direction of the winding axis.

13. The battery cell according to claim 11, characterized in that: Along the extension direction of the winding axis, the size of the insulating member is W1, the size of the negative electrode active material layer is W2, and 0.8≤W1 / W2≤0.

95.

14. The battery cell according to claim 1, characterized in that: Along the thickness direction of the electrode assembly, the negative electrode tail section is located outside the positive electrode tail end.

15. The battery cell according to claim 14, characterized in that: The insulating member is connected to the inner surface of the negative electrode tail section.

16. The battery cell according to claim 1, characterized in that: The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer, and along the thickness direction of the negative electrode plate, the negative electrode active material layer is disposed on at least one side of the negative electrode current collector; The material of the negative electrode active material layer includes silicon element. In the negative electrode active material layer, the weight percentage of the silicon element is G, and 0.5%≤G≤10%.

17. The battery cell according to claim 16, characterized in that: 2％≤G。 18. The battery cell according to claim 1, characterized in that: Along the winding direction, the length of the negative electrode tail section is L3, 3mm≤L3≤10mm.

19. The battery cell according to claim 18, characterized in that: 5mm≤L3≤8mm.

20. The battery cell according to claim 1, characterized in that: The insulating member includes adhesive tape or insulating coating.

21. The battery cell according to claim 1, characterized in that: The battery cell is a cylindrical battery cell.

22. An electrical equipment, characterized in that: Comprising a battery cell according to any one of claims 1-21.

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