Battery cell and electric equipment

Abstract

The invention provides a battery cell and electric equipment, the battery cell comprises an electrode assembly, the electrode assembly comprises a first pole piece, the first pole piece comprises a first current collector, a first active material layer and an insulating layer, at least one first surface of the first current collector is provided with the first active material layer and the insulating layer along the thickness direction of the first current collector, and the first active material layer and the insulating layer are arranged on the second surface of the first current collector. One part of the first active material layer and one part of the insulating layer are overlapped to form an overlapping region, and the insulating layer is located between the first current collector and the first active material layer in the overlapping region; in the width direction of the first pole piece, the first active material layer comprises a first region which is not overlapped with the insulating layer and is positioned on the first surface, and the insulating layer comprises a second region which is not overlapped with the first active material layer and is positioned on the first surface, so that the connection stability of the insulating layer on the first current collector can be improved; the first active material layer does not have an area covered by the insulating layer, and the first active material layer can exert the capacity, so that the cell has relatively high energy density.

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, the output of battery cells is increasing, so higher requirements are placed on the energy density 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 energy density of the battery cell.

[0004] In a first aspect, an embodiment of the present application provides a battery cell, wherein the battery cell comprises an electrode assembly, wherein the electrode assembly comprises a first pole piece, wherein the first pole piece comprises a first current collector, a first active material layer and an insulating layer, wherein along the thickness direction of the first current collector, at least one first surface of the first current collector is provided with the first active material layer and the insulating layer; wherein, along the thickness direction of the first pole piece, a portion of the first active material layer overlaps with a portion of the insulating layer to form an overlapping area, and within the overlapping area, the insulating layer is located between the first current collector and the first active material layer; along the width direction of the first pole piece, the first active material layer comprises a first area that does not overlap with the insulating layer and is located on the first surface, and the insulating layer comprises a second area that does not overlap with the first active material layer and is located on the first surface, and the overlapping area is located between the first area and the second area.

[0005] In one or more optional embodiments above, a portion of the first active material layer overlaps a portion of the insulating layer in the thickness direction of the first pole piece to form an overlapping area. In the overlapping area, the insulating layer is located between the first current collector and the first active material layer, that is, part of the insulating layer is covered by the first active material layer, which can improve the connection stability of the insulating layer on the first current collector. There is no area of ​​the first active material layer covered by the insulating layer. The first active material layer can exert its capacity, avoiding the waste of the first active material layer due to being covered by the insulating layer, so that the battery cell has a higher energy density. The first active material layer includes a first area that does not overlap with the insulating layer and is located on the first surface, and the insulating layer includes a second area that does not overlap with the first active material layer and is located on the first surface. Along the width direction of the first pole piece, the overlapping area is located between the first area and the second area. In the width direction of the first pole piece, the second area of ​​the insulating layer can cover the empty foil area of ​​the first current collector where the first active material layer is not set, reducing the risk of short circuit of the battery cell after the burr pierces the isolation membrane, and improving the safety performance of the battery cell.

[0006] In some embodiments of the first aspect of the present application, along the width direction of the first pole piece, the width of the overlapping area is W1 mm, the width of the second area is W2 mm, and 0.3≤W1 / (W1+W2)≤0.5.

[0007] In one or more of the above optional embodiments, by W1 / (W1+W2)≥0.3, the width of the insulating layer in the overlapping area along the width direction of the first pole piece is larger, which increases the area covered by the first active material layer of the insulating layer, reduces the risk of the insulating layer falling off, and is beneficial to improving the connection stability of the insulating layer. At the same time, it can also make the area of ​​the first active material layer larger in the overlapping area, which is beneficial for the battery cell to have a higher energy density. By W1 / (W1+W2)≤0.5, the width of the second area of ​​the insulating layer is prevented from being too small, so that the insulating layer can play a good role in reducing the risk of short circuit of the battery cell. Therefore, by 0.3≤W1 / (W1+W2)≤0.5, the connection stability of the insulating member can be improved, and the size of the second area of ​​the insulating layer not covered by the first active material layer in the width direction of the first pole piece can be larger, so that the insulating layer can play a good role in reducing the risk of short circuit of the battery cell.

[0008] In some embodiments of the first aspect of the present application, along the width direction of the first pole piece, the width of the overlapping area is W1 mm, the width of the second area is W2 mm, and 3≤W1+W2≤5.

[0009] In one or more of the above optional embodiments, by W1+W2≥3, the insulating layer has a larger coverage area, which can better reduce the risk of burrs piercing the isolation membrane and causing the battery cell to short-circuit, thereby improving the safety performance of the battery cell. By W1+W2≤5, the influence of the insulating layer on the size of the battery cell can be reduced, thereby reducing the influence of the insulating layer on the energy density of the battery cell. Therefore, by 3≤W1+W2≤5, the safety performance of the battery cell can be improved, and the influence of the insulating layer on the energy density of the battery cell can be reduced, so that the battery cell has a higher energy density.

[0010] In some embodiments of the first aspect of the present application, along the width direction of the first pole piece, the width of the overlapping area is W1 mm, 1≤W1≤2.5.

[0011] In one or more of the above optional embodiments, by setting W1≥1, the width of the overlapping area along the width direction of the first pole piece is larger, which increases the area covered by the first active material layer of the insulating layer, reduces the risk of the insulating layer detaching from the first current collector, and improves the connection stability of the insulating layer. By setting W1≤2.5, the effect of the insulating layer on the size of the battery cell can be reduced, thereby reducing the effect of the insulating layer on the energy density of the battery cell and reducing the effect on the rate of the battery cell. Therefore, by setting 1≤W1≤2.5, the connection stability of the insulating layer can be improved, and the battery cell can have a higher energy density and better rate performance.

[0012] In some embodiments of the first aspect of the present application, the thickness of the insulating layer at any position is greater than or equal to 4 μm and less than or equal to 10 μm.

[0013] In one or more of the above optional embodiments, by making the thickness of the insulating layer at any position greater than or equal to 4μm, the risk of the insulating layer being pierced by burrs and causing a short circuit in the battery cell is reduced, which is beneficial to improving the safety of the battery cell. The thickness of the insulating layer at any position is less than or equal to 10μm, which can reduce the space occupied by the insulating layer inside the battery cell, thereby reducing the influence of the insulating layer on the energy density of the battery cell, so that the battery cell has a higher energy density. Therefore, by making the thickness of the insulating layer at any position greater than or equal to 4μm and less than or equal to 10μm, the safety performance of the battery cell can be improved and the battery cell can have a higher energy density.

[0014] In some embodiments of the first aspect of the present application, the insulating layer includes a third region located in the overlapping region, and a thickness of the third region is less than or equal to a thickness of the second region.

[0015] In one or more of the above optional embodiments, by setting the thickness of the insulating layer in the third zone of the overlapping area to be less than or equal to the thickness of the second zone, the size of the first active material layer protruding from the surface of the first zone of the first active material layer in the overlapping area is smaller, thereby reducing the difference in thickness between the overlapping area and the thickness of other areas of the first electrode sheet, and further reducing the size difference between the area corresponding to the overlapping area and other areas of the electrode assembly, which is beneficial to uniform force on the electrode sheet after expansion of the electrode assembly, thereby reducing the risk of wrinkling, fracture, lithium deposition and other problems in the electrode sheet.

[0016] In some embodiments of the first aspect of the present application, the insulating layer includes a third region located in the overlapping region, the thickness of the third region is T1 μm, the thickness of the first active material layer located in the first region is T2 μm, and 0.1≤T1 / T2≤0.25.

[0017] In one or more of the above optional embodiments, the ratio of the thickness of the insulating layer in the overlapping area to the thickness of the first area of ​​the first active material layer is greater than or equal to 0.1, which facilitates the manufacture of the insulating layer. By making the ratio of the thickness of the insulating layer in the overlapping area to the thickness of the first area of ​​the first active material layer less than or equal to 0.25, the risk of the first active material layer falling off in the overlapping area is reduced, and the problem of the first active material layer protruding out of the first area in the overlapping area can also be alleviated, so that the thickness of the overall structure formed by the first pole piece and the insulating layer is more uniform, and the risk of wrinkles, fractures, lithium precipitation and other problems in the pole piece of the battery cell due to uneven force is reduced. Therefore, by 0.1≤T1 / T2≤0.25, the manufacturing and molding of the electrode assembly is facilitated, and the size of the electrode assembly can also be made more uniform.

[0018] In some embodiments of the first aspect of the present application, the insulating layer includes a substrate and two adhesive layers, along the thickness direction of the substrate, the two adhesive layers are respectively arranged on two opposite surfaces of the substrate, along the width direction of the first pole piece, a part of the adhesive layer and a part of the substrate are located in the overlapping area, and another part of the adhesive layer and another part of the substrate are located in the second area; one of the two adhesive layers connects the substrate and the first current collector, and the other of the two adhesive layers connects the substrate and the first active material layer.

[0019] In one or more optional embodiments above, the insulating layer includes a substrate and two adhesive layers, one of the two adhesive layers connects the substrate and the first current collector, and the other of the two adhesive layers connects the substrate and the first active material layer, so that the substrate and the first active material layer are more conveniently connected to the insulating layer, and the insulating layer is less likely to fall off from the first current collector, and the thickness of the second region is easier to control, so that the thickness of the insulating layer is more uniform. The weight of the insulating layer formed by the substrate and the two adhesive layers is lighter and easier to control, which is beneficial to reducing the influence of the insulating layer on the weight of the battery cell, thereby facilitating the improvement of the energy density of the battery cell.

[0020] In some embodiments of the first aspect of the present application, the thickness of the adhesive layer is T3 μm, the thickness of the substrate is T4 μm, and 0.1≤T3 / T4≤0.25.

[0021] In one or more optional embodiments above, by T3 / T4≥0.1, the adhesive layer has better adhesive properties. T3 / T4≤0.25 avoids the excessive thickness of the adhesive layer causing the thickness of the substrate to be too small, so that the substrate has a larger thickness, and the insulating member has better strength. Therefore, by 0.1≤T3 / T4≤0.25, the adhesive layer has better adhesive properties and the insulating member has better strength.

[0022] In some embodiments of the first aspect of the present application, the insulating layer includes a third region located in the overlapping region, the third region is provided with a plurality of through holes, and along the thickness direction of the insulating layer, the through holes penetrate two opposite sides of the third region.

[0023] In one or more of the above optional embodiments, a plurality of through holes are provided in the third region of the insulating layer located in the overlapping area, and the through holes penetrate the opposite sides of the third region along the thickness direction of the insulating layer. Then, the electrons of the first active material layer located in the overlapping area can reach the first current collector through the through holes, thereby shortening the transmission path of the electrons of the first active material layer in the overlapping area, thereby improving the rate performance and power capacity of the battery cell.

[0024] In some embodiments of the first aspect of the present application, when observed along the thickness direction of the third region, the sum of the areas of all through holes is S1 mm 2 , the area of ​​the third zone is Smm 2 , 0.2≤S1 / S≤0.5.

[0025] In one or more of the above optional embodiments, by S1 / S≥0.2, the total area of ​​all through holes is made larger, reducing the transmission power loss of electrons caused by the insulating layer being arranged between the first active material layer and the first current collector. By S1 / S≤0.5, the problem of reduced connection area between the insulating layer and the first current collector due to the provision of through holes is alleviated, and the risk of detachment of the insulating layer is reduced. Therefore, by 0.2≤S1 / S≤0.5, the transmission path of electrons in the first active material layer in the overlapping area can be shortened, the transmission power loss of electrons caused by the insulating layer being arranged between the first active material layer and the first current collector can be reduced, and the risk of detachment of the insulating layer from the first current collector due to the provision of through holes can be reduced.

[0026] In some embodiments of the first aspect of the present application, the first pole piece also includes a first empty foil area, along the width direction of the first pole piece, the first empty foil area is connected to one end of the first current collector, and protrudes from one end of the second area away from the overlapping area, along the length direction of the first pole piece after it is unfolded, the ratio of the length of the first empty foil area to the length of the first current collector is greater than or equal to 0.5, and less than or equal to 1.

[0027] In one or more of the above optional embodiments, along the length direction of the first pole sheet after unfolding, the ratio of the length of the first empty foil area to the length of the first current collector is greater than or equal to 0.5, and less than or equal to 1, so that the first empty foil area has a larger size in the length direction after the first pole sheet is unfolded, which is beneficial for the first empty foil area to have better current carrying capacity and to improve the charging rate of the battery cell.

[0028] In some embodiments of the first aspect of the present application, along the width direction of the first pole piece, the width of the first empty foil area is L mm, 3≤L≤5.

[0029] In one or more of the above optional embodiments, by L≥3, the first empty foil area is larger in size in the width direction of the first pole piece, which is convenient for connecting the first empty foil area with other structures, and also reduces the risk of squeezing and damaging the insulating layer when the first empty foil area is flattened. L≤5, it is prevented that the size of the first empty foil area in the width direction of the first pole piece is too large, resulting in the size of the first active material layer in the width direction of the first pole piece being too small, which is beneficial for the battery cell to have a higher energy density. Therefore, by 3≤L≤5, it is convenient for the first empty foil area to be connected with other structures, reduces the risk of squeezing and damaging the insulating layer when the first empty foil area is flattened, and is also beneficial for the battery cell to have a higher energy density.

[0030] In some embodiments of the first aspect of the present application, the first pole piece further includes a first pole ear, which is connected to one end of the first current collector along the width direction of the first pole piece and protrudes from one end of the second region away from the overlapping region, and along the length direction of the unfolded first pole piece, the ratio of the size of the first pole ear to the size of the first current collector is less than 0.5; the insulating layer further includes a fourth region, the fourth region is connected to one end of the second region away from the overlapping region, and the fourth region covers a portion of the surface of the first pole ear.

[0031] In one or more of the above optional embodiments, the fourth region of the insulating layer covers a portion of the surface of the first pole ear, which is beneficial to reducing the risk of burrs at the first pole ear piercing the isolation membrane and causing a short circuit in the battery cell, and is beneficial to improving the safety performance of the battery cell.

[0032] In some embodiments of the first aspect of the present application, the insulating layer is an integrally formed structure.

[0033] In one or more of the above optional embodiments, the insulating layer is an integrally formed structure, which facilitates the manufacture of the insulating layer and also makes the insulating layer have higher strength.

[0034] In some embodiments of the first aspect of the present application, the insulating layer is adhesive tape or an insulating coating.

[0035] In one or more optional embodiments above, the insulating layer is adhesive tape, which has low cost, good adhesive properties and is convenient to be arranged in the battery cell. The adhesive tape is soft and can be easily wound together with the first pole piece, the second pole piece and the isolation film when the electrode assembly is a winding structure, and the risk of warping of the adhesive tape is low. The insulating layer is an insulating coating, which is convenient for the insulating layer to be arranged on the first pole piece.

[0036] In some embodiments of the first aspect of the present application, the battery cell also includes a second pole piece, the polarities of the first pole piece and the second pole piece are opposite, the second pole piece includes a second active material layer, and along the width direction of the first pole piece, the second active material layer exceeds the overlapping area close to one end of the second area.

[0037] In one or more of the above optional embodiments, along the width direction of the first pole piece, the second active material layer exceeds the overlapping area close to one end of the second area, and the risk of the burrs at the first pole ear piercing the isolation membrane and contacting the second pole piece to cause a short circuit is low. The insulating layer acts as a separator between the first pole ear and the second pole piece, thereby reducing the risk of short circuit in the battery cell.

[0038] In some embodiments of the first aspect of the present application, the first pole piece is a positive pole piece.

[0039] In one or more of the above optional embodiments, the first pole piece is the positive pole piece, and the second pole piece is the negative pole piece. The insulating layer is arranged on the positive pole piece. The insulating layer can play a role of separation and insulation between the positive pole piece and the negative pole piece, thereby reducing the risk of burrs at the pole ear of the negative pole piece piercing the isolation membrane and the insulating layer and causing a short circuit in the battery cell, thereby improving the safety performance of the battery cell.

[0040] In a second aspect, an embodiment of the present application further provides an electrical device, the electrical device comprising a battery cell provided by any of the above embodiments.

[0041] In one or more of the above optional embodiments, the battery cell provided in any of the above embodiments has higher energy density and safety performance, which is beneficial to improving the power reliability of the electrical equipment powered by the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] 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.

[0043] Figure 1 An exploded diagram of a battery cell provided in some embodiments of the present application;

[0044] Figure 2 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0045] Figure 3 A view of a first pole piece in an unfolded state along its thickness direction provided in some embodiments of the present application;

[0046] Figure 4 A view of a first pole piece in an unfolded state along its length direction provided in some embodiments of the present application;

[0047] Figure 5 A view of a first pole piece in an unfolded state along its length direction provided in some other embodiments of the present application;

[0048] Figure 6 A view of a first pole piece in an unfolded state along its length direction provided in some other embodiments of the present application;

[0049] Figure 7 A view of a first pole piece in an unfolded state along its thickness direction provided in some further embodiments of the present application;

[0050] Figure 8 A view of a first pole piece in an unfolded state along its length direction provided in some further embodiments of the present application;

[0051] Fig. 9 A view of a first pole piece in an unfolded state along its thickness direction provided in some other embodiments of the present application;

[0052] Fig.10 A view of a first pole piece in an unfolded state along its thickness direction provided in still other embodiments of the present application;

[0053] Fig.11 A view of a first pole piece in an unfolded state along its length direction provided in still other embodiments of the present application;

[0054] Fig.12 A view along the length direction of the first pole piece provided in some embodiments of the present application of a first pole piece, a second pole piece, and an isolation film after being stacked and not wound.

[0055] Icon: 100-battery cell; 10-shell; 11-shell; 12-cover; 20-electrode assembly; 21-first pole piece; 211-first current collector; 2111-first surface; 212-first active material layer; 2121-first zone; 2122-fifth zone; 213-insulating layer; 2131-second zone; 2132-third zone; 2133-substrate; 2134-adhesive layer; 2135-through hole; 2136-fourth zone; 214-first pole ear; 215-first empty foil zone; 22-second pole piece; 221-second current collector; 222-second active material layer; 223-second pole ear; 23-isolating film; X-thickness direction of the first pole piece; Y-width direction of the first pole piece; Z-length direction of the first pole piece; Q-overlapping zone. DETAILED DESCRIPTION

[0056] 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.

[0057] 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 claimed for protection, but merely represents selected embodiments of the present application. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0058] 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.

[0059] 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.

[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.

[0061] The electrode assembly of the battery cell includes two polarity opposite polarity pole pieces. In order to improve the safety performance of the battery cell, in the width direction of the pole piece, at least one of the two pole pieces is provided with an insulating layer near the pole ear to reduce the risk of the battery cell short circuit caused by burrs generated when the two pole pieces with opposite polarity form the pole ear and pierce the isolation film, thereby improving the safety performance of the battery cell. Along the width direction of the pole piece, part of the insulating layer covers part of the active material layer of the pole piece, and another part of the insulating layer covers the empty foil area of ​​the pole piece. The active material in the area covered by the insulating layer cannot exert its capacity, resulting in waste of active materials and reduced energy density of the battery cell. In addition, the insulating layer covering the active material layer of the pole piece may also make the insulating layer easy to fall off, and the stability is poor.

[0062] Based on the above considerations, in order to improve the energy density of the battery cell and the stability of the insulating layer, an embodiment of the present application provides a battery cell, which includes an electrode assembly, the electrode assembly includes a first pole piece, the first pole piece includes a first current collector, a first active material layer and an insulating layer, and along the thickness direction of the first current collector, at least one first surface of the first current collector is provided with the first active material layer and the insulating layer; wherein, along the thickness direction of the first pole piece, a portion of the first active material layer overlaps with a portion of the insulating layer to form an overlapping area, and within the overlapping area, the insulating layer is located between the first current collector and the first active material layer; along the width direction of the first pole piece, the first active material layer includes a first area that does not overlap with the insulating layer and is located on the first surface, the insulating layer includes a second area that does not overlap with the first active material layer and is located on the first surface, and the overlapping area is located between the first area and the second area.

[0063] By overlapping a part of the first active material layer with a part of the insulating layer in the thickness direction of the first pole piece to form an overlapping area, in the overlapping area, the insulating layer is located between the first current collector and the first active material layer, that is, part of the insulating layer is covered by the first active material layer, which can improve the connection stability of the insulating layer on the first current collector, and there is no area of ​​the first active material layer covered by the insulating layer. The first active material layer can exert its capacity, avoiding the waste of the first active material layer due to being covered by the insulating layer, so that the battery cell has a higher energy density. The first active material layer includes a first area that does not overlap with the insulating layer and is located on the first surface, and the insulating layer includes a second area that does not overlap with the first active material layer and is located on the first surface. Along the width direction of the first pole piece, the overlapping area is located between the first area and the second area. In the width direction of the first pole piece, the second area of ​​the insulating layer can cover the empty foil area of ​​the first current collector where the first active material layer is not set, reducing the risk of short circuit of the battery cell after the burr pierces the isolation membrane, and improving the safety performance of the battery cell.

[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 formed by the pole piece having the working conditions of the present application can also be used as the power supply system of the electrical equipment.

[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 2As shown, the 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, such as 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, such as an aluminum-plastic film or a steel-plastic film, forming a soft-pack 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] like Figure 2 As shown, the electrode assembly 20 includes a first electrode sheet 21 , a second electrode sheet 22 and a separation membrane 23 .

[0070] The first pole piece 21 and the second pole piece 22 have opposite polarities, that is, one of the first pole piece 21 and the second pole piece 22 is a positive pole piece, and the other of the first pole piece 21 and the second pole piece 22 is a negative pole piece.

[0071] The first pole piece 21 includes a first current collector 211 and a first active material layer 212. Along the thickness direction of the first current collector 211, the first current collector 211 has two opposite first surfaces 2111, and at least one of the two first surfaces 2111 is provided with a first active material layer 212. In the embodiment where the first pole piece 21 is a positive pole piece, the first current collector 211 is a positive current collector, and the first active material layer 212 is a positive active material layer. A positive active material layer is provided on at least one side of the positive current collector. For lithium-ion batteries, the material of the positive current collector may be aluminum. The positive active material layer may be lithium cobalt oxide, lithium iron phosphate, lithium iron manganese phosphate, ternary material (such as NCM) or lithium manganate, etc. The positive current collector may be a composite current collector or a non-composite current collector.

[0072] In the embodiment where the first electrode sheet 21 is a negative electrode sheet, the first current collector 211 is a negative electrode current collector, and the first active material layer 212 is a negative electrode active material layer. A negative electrode active material layer is provided on at least one side of the negative electrode current collector. For lithium-ion batteries, the material of the negative electrode current collector may be copper. The negative electrode current collector may be a composite current collector or a non-composite current collector. The negative electrode active material may be a carbon material or a silicon material, etc.

[0073] The separator 23 insulates and separates the positive electrode sheet and the negative electrode sheet 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).

[0074] The electrode assembly 20 may be a laminated structure or a wound structure.

[0075] In the embodiment where the electrode assembly 20 is a laminated structure, the first electrode sheet 21 , the isolation membrane 23 , and the second electrode sheet 22 are laminated one or more times in a certain order.

[0076] In the embodiment in which the electrode assembly 20 is a wound structure, the first electrode sheet 21, the separator 23, the second electrode sheet 22 and the other separator 23 are stacked in a certain order and then wound to form the electrode assembly 20 of the wound structure; or, the separator 23, the first electrode sheet 21, the other separator 23 and the second electrode sheet 22 are stacked in a certain order and then wound to form the electrode assembly 20 of the wound structure. The wound electrode assembly 20 can be a flat wound electrode assembly 20 or a cylindrical electrode assembly 20. In the embodiment in which the electrode assembly 20 is a cylindrical structure, the battery cell 100 can be a cylindrical battery cell 100 or a columnar battery cell 100. Figure 1 FIG. 4 shows a case where the battery cell 100 is a cylindrical battery cell 100. Figure 2 , the electrode assembly 20 is shown as a wound structure and a cylindrical structure.

[0077] like Figure 3 , Figure 4 As shown, the first electrode sheet 21 further includes an insulating layer 213 , and at least one first surface 2111 of the first current collector 211 is provided with a first active material layer 212 and an insulating layer 213 .

[0078] Among them, only one of the two first surfaces 2111 may be provided with the first active material layer 212 and the insulating layer 213 . Alternatively, both first surfaces 2111 may be provided with the first active material layer 212 and the insulating layer 213 . Figure 3 and Figure 4 2 shows a case where the first active material layer 212 is provided on both first surfaces 2111 .

[0079] Along the thickness direction X of the first pole piece, a portion of the first active material layer 212 overlaps with a portion of the insulating layer 213 to form an overlapping region Q. In the overlapping region Q, the insulating layer 213 is located between the first current collector 211 and the first active material layer 212. Along the width direction Y of the first pole piece, the first active material layer 212 includes a first region 2121 that does not overlap with the insulating layer 213 and is located on the first surface 2111. The insulating layer 213 includes a second region 2131 that does not overlap with the first active material layer 212 and is located on the first surface 2111. The overlapping region Q is located between the first region 2121 and the second region 2131.

[0080] An overlapping region Q is formed by overlapping a portion of the first active material layer 212 with a portion of the insulating layer 213 in the thickness direction X of the first electrode sheet. In the overlapping region Q, the insulating layer 213 is located between the first current collector 211 and the first active material layer 212, that is, a portion of the insulating layer 213 is covered by the first active material layer 212, which can improve the connection stability of the insulating layer 213 on the first current collector 211. There is no area of ​​the first active material layer 212 covered by the insulating layer 213, and the first active material layer 212 can exert its capacity, thereby avoiding the waste of the first active material layer 212 due to being covered by the insulating layer 213, so that the battery cell 100 has a higher energy density. The first active material layer 212 includes a first area 2121 that does not overlap with the insulating layer 213 and is located on the first surface 2111. The insulating layer 213 includes a second area 2131 that does not overlap with the first active material layer 212 and is located on the first surface 2111. Along the width direction Y of the first pole piece, the overlapping area Q is located between the first area 2121 and the second area 2131. In the width direction Y of the first pole piece, the second area 2131 of the insulating layer 213 can cover the empty foil area of ​​the first current collector 211 where the first active material layer 212 is not set, thereby reducing the risk of short circuit of the battery cell 100 after the burrs pierce the isolation membrane 23, thereby improving the safety performance of the battery cell 100.

[0081] It should be noted that the thickness direction X of the first pole piece is parallel to the thickness direction of the first current collector 211. When the first pole piece 21 is in the unfolded state, the width direction Y of the first pole piece is perpendicular to the thickness direction X of the first pole piece. When the first pole piece 21 is in the wound state, the width direction Y of the first pole piece is parallel to the extension direction of the winding axis.

[0082] The first region 2121 of the first active material layer 212 is directly disposed on the first surface 2111 and covers a portion of the first surface 2111. Along the width direction Y of the first electrode sheet, one end of the first region 2121 away from the overlapping region Q is flush with the edge of the first surface 2111.

[0083] The second region 2131 of the insulating layer 213 is directly disposed on the first surface 2111 and covers a portion of the first surface 2111. Along the width direction Y of the first electrode sheet, one end of the second region 2131 away from the overlapping region Q is flush with the edge of the first surface 2111.

[0084] The insulating layer 213 includes a third region 2132 located in the overlapping region Q. The third region 2132 is directly disposed on the first surface 2111. Along the width direction Y of the first electrode sheet, one end of the third region 2132 away from the first region 2121 is connected to the second region 2131.

[0085] The first active material layer 212 includes a fifth region 2122 located in the overlapping region Q. The fifth region 2122 is directly disposed on the surface of the third region 2132 away from the first surface 2111. Along the width direction Y of the first electrode sheet, one end of the fifth region 2122 away from the second region 2131 is connected to the first region 2121.

[0086] In some embodiments, the insulating layer 213 may be an integrally formed structure, for example, the insulating layer 213 is a coating formed by coating, the insulating layer 213 is an integrally formed adhesive tape, etc. The insulating layer 213 is an integrally formed structure, which facilitates the manufacturing of the insulating layer 213 and also makes the insulating layer 213 have a higher strength.

[0087] The insulating layer 213 can have various structural forms, for example, Figure 4 As shown, the insulating layer 213 is an insulating coating, that is, the insulating layer 213 is an insulating coating formed on the first current collector 211 by coating slurry. The insulating layer 213 is an insulating coating, which facilitates the insulating layer 213 to be disposed on the first pole piece 21 .

[0088] In other embodiments, the insulating layer 213 may be adhesive tape. The insulating layer 213 is adhesive tape, which has low cost, good adhesive properties, and is convenient to be set in the battery cell 100. The adhesive tape is soft and can be easily wound together with the first pole piece 21, the second pole piece 22, and the isolation film 23 when the electrode assembly 20 is a winding structure. The risk of warping of the adhesive tape is low. The insulating layer 213 is an insulating coating, which facilitates the insulating layer 213 to be set on the first pole piece 21.

[0089] In an embodiment where the insulating layer 213 is adhesive tape, the insulating layer 213 may include a substrate 2133 and two adhesive layers 2134. Along the thickness direction of the substrate 2133, the two adhesive layers 2134 are respectively arranged on two opposite surfaces of the substrate 2133. Along the width direction Y of the first pole piece, a portion of the adhesive layer 2134 and a portion of the substrate 2133 are located in the overlapping area Q, and another portion of the adhesive layer 2134 and another portion of the substrate 2133 are located in the second area 2131; one of the two adhesive layers 2134 connects the substrate 2133 and the first current collector 211, and the other of the two adhesive layers 2134 connects the substrate 2133 and the first active material layer 212.

[0090] When the first pole piece 21 is in the unfolded state, the thickness direction of the substrate 2133 , the thickness direction X of the first pole piece, and the thickness direction of the first current collector 211 are parallel.

[0091] The substrate 2133 is the skeleton of the insulating layer 213 and has an important influence on the strength of the insulating layer 213 .

[0092] The adhesive layer 2134 is a structure that plays a connecting role in the insulating layer 213. The material of the adhesive layer 2134 includes one or more of acrylic glue, isooctyl acrylate, butyl methacrylate, isooctyl acrylate, octyl methacrylate, methyl methacrylate, and butyl acrylate.

[0093] like Figure 5 As shown, the insulating layer 213 includes a substrate 2133 and two adhesive layers 2134, one of the two adhesive layers 2134 connects the substrate 2133 and the first current collector 211, and the other of the two adhesive layers 2134 connects the substrate 2133 and the first active material layer 212, so that the substrate 2133 and the first active material layer 212 are more conveniently connected to the insulating layer 213, and the insulating layer 213 is less likely to fall off from the first current collector 211, and the thickness of the second area 2131 is easier to control, so that the thickness of the insulating layer 213 is more uniform. The weight of the insulating layer 213 formed by the substrate 2133 and the two adhesive layers 2134 is lighter and easier to control, which is conducive to reducing the influence of the insulating layer 213 on the weight of the battery cell 100, thereby facilitating the improvement of the energy density of the battery cell 100.

[0094] like Figure 5 As shown, in some embodiments, the thickness of the adhesive layer 2134 is T3 μm, the thickness of the substrate 2133 is T4 μm, and 0.1≤T3 / T4≤0.25.

[0095] The thickness T3 of the adhesive layer 2134 is the dimension of the adhesive layer 2134 along the thickness direction X of the first pole piece, and is also the distance between two opposite surfaces of the adhesive layer 2134 in the thickness direction X of the first pole piece. The thickness T4 of the substrate 2133 is the dimension of the substrate 2133 along the thickness direction X of the first pole piece, and is also the distance between two opposite surfaces of the substrate 2133 in the thickness direction X of the first pole piece.

[0096] Illustratively, T3 / T4 may be 0.1, 0.12, 0.13, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.25, etc.

[0097] By setting T3 / T4≥0.1, the adhesive layer 2134 has better adhesive properties. By setting T3 / T4≤0.25, the thickness of the adhesive layer 2134 is prevented from being too large, which causes the thickness of the substrate 2133 to be too small, so that the substrate 2133 has a larger thickness, and the insulating member has better strength. Therefore, by setting 0.1≤T3 / T4≤0.25, the adhesive layer 2134 has better adhesive properties, and the insulating member also has better strength.

[0098] In some embodiments, the insulating layer 213 may be of uniform thickness, that is, the thickness of any position of the insulating layer 213 is the same, which facilitates the manufacturing and molding of the insulating layer 213 .

[0099] In some other embodiments, the insulating layer 213 may be a non-uniform thickness structure, that is, the insulating layer 213 has at least two locations with different thicknesses.

[0100] For example, Figure 6 As shown, in some embodiments, the thickness of the third region 2132 of the insulating layer 213 is less than the thickness of the second region 2131. Specifically, the thickness of the third region 2132 is T1 μm, the thickness of the second region 2131 is T'1 μm, and T1<T'1. In other embodiments, the insulating layer 213 with different thicknesses as above is also disposed on the other surface of the first current collector 211.

[0101] By setting the thickness of the third area 2132 of the insulating layer 213 in the overlapping area Q to be smaller than the thickness of the second area 2131, the size of the first active material layer 212 protruding from the surface of the first area 2121 of the first active material layer 212 in the overlapping area Q is smaller, thereby reducing the difference in thickness between the overlapping area Q and the thickness of other areas of the first electrode sheet 21, and further reducing the size difference between the area of ​​the electrode assembly 20 corresponding to the overlapping area Q and other areas of the electrode assembly 20, which is beneficial to uniform force on the electrode sheet after the electrode assembly 20 expands, thereby reducing the risk of wrinkles, fractures, lithium deposition and other problems on the electrode sheet.

[0102] The thickness of the insulating layer 213 may be the same as the thickness of the first active material layer 212 , that is, the thickness of any position of the insulating layer 213 is the same as the thickness of any position of the first active material layer 212 .

[0103] Of course, the thickness of the insulating layer 213 and the thickness of the first active material layer 212 may also be different, that is, the thickness of at least a portion of the insulating layer 213 is different from the thickness of at least a portion of the first active material layer 212 .

[0104] It should be noted that the thickness of the insulating layer 213 is the distance between the two opposite surfaces of the insulating layer 213 in the thickness direction X of the first pole piece. In the embodiment where the insulating layer 213 includes a substrate 2133 and two adhesive layers 2134, the two opposite surfaces of the insulating layer 213 in the thickness direction X of the first pole piece are respectively the surfaces of the two adhesive layers 2134 facing away from the substrate 2133. The thickness of the first active material layer 212 is the distance between the two opposite surfaces of the first active material layer 212 in the thickness direction X of the first pole piece, that is, the distance between the surface facing the first current collector 211 and the surface facing away from the current collector in the thickness direction X of the first pole piece.

[0105] For example, Figure 4 As shown, in some embodiments, the thickness of the third region 2132 is T1 μm, the thickness of the first active material layer 212 located in the first region 2121 is T2 μm, and 0.1≤T1 / T2≤0.25.

[0106] That is, the thickness of the third region 2132 of the insulating layer 213 is different from the thickness of the first active material layer 212 in the first region 2121 , and the thickness of the third region 2132 is smaller than the thickness of the first active material layer 212 in the first region 2121 .

[0107] In the embodiment where the insulating layer 213 includes a substrate 2133 and two adhesive layers 2134 , the thickness T1 of the third region 2132 may be the sum of the thickness T4 of the substrate 2133 and the thickness T3 of the two adhesive layers 2134 , ie, T1 = T4 + 2T3 .

[0108] Illustratively, T1 / T2 may be 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, etc.

[0109] By setting the ratio of the thickness of the insulating layer 213 in the overlapping region Q to the thickness of the first region 2121 of the first active material layer 212 to be greater than or equal to 0.1, the manufacturing of the insulating layer 213 is facilitated. By setting the ratio of the thickness of the insulating layer 213 in the overlapping region Q to the thickness of the first region 2121 of the first active material layer 212 to be less than or equal to 0.25, the risk of the first active material layer 212 falling off in the overlapping region Q is reduced, and the problem of the first active material layer 212 in the overlapping region Q protruding from the first region 2121 is also alleviated, so that the thickness of the overall structure formed by the first pole piece 21 and the insulating layer 213 is more uniform, and the risk of wrinkles, fractures, lithium precipitation, etc. of the pole piece of the battery cell 100 due to uneven force is reduced. Therefore, by setting 0.1≤T1 / T2≤0.25, the manufacturing and molding of the electrode assembly 20 is facilitated, and the size of the electrode assembly 20 can also be made more uniform.

[0110] In some embodiments, the thickness of the insulating layer 213 at any position is greater than or equal to 4 μm and less than or equal to 10 μm.

[0111] Exemplarily, 4 μm ≤ T1 ≤ 10 μm.

[0112] For example, the thickness of the insulating layer 213 at any position may be 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, etc.

[0113] By making the thickness of the insulating layer 213 at any position greater than or equal to 4 μm, the risk of the insulating layer 213 being pierced by burrs and causing the battery cell 100 to short-circuit is reduced, which is conducive to improving the safety of the battery cell 100. The thickness of the insulating layer 213 at any position is less than or equal to 10 μm, which can reduce the space occupied by the insulating layer 213 inside the battery cell 100, thereby reducing the influence of the insulating layer 213 on the energy density of the battery cell 100, so that the battery cell 100 has a higher energy density. Therefore, by making the thickness of the insulating layer 213 at any position greater than or equal to 4 μm and less than or equal to 10 μm, the safety performance of the battery cell 100 can be improved, and the battery cell 100 can have a higher energy density.

[0114] like Figure 3 , Figure 4 As shown, in some embodiments, along the width direction Y of the first pole piece, the width of the overlapping region Q is W1 mm, the width of the second region 2131 is W2 mm, and 0.3≤W1 / (W1+W2)≤0.5.

[0115] Along the width direction Y of the first electrode sheet, the width W1 of the overlapping region Q is also the width of the third region 2132 and the width of the fifth region 2122 of the first active material layer 212. W1+W2 is the sum of the width of the third region 2132 and the width of the second region 2131 along the width direction Y of the first electrode sheet.

[0116] Along the width direction Y of the first electrode sheet, the width W1 of the overlapping region Q is also the width of the fifth region 2122 of the first active material layer 212 .

[0117] For example, W1 / (W1+W2) can be 0.3, 0.32, 0.35, 0.37, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, etc.

[0118] By W1 / (W1+W2)≥0.3, the width of the insulating layer 213 in the overlapping area Q along the width direction Y of the first pole piece is larger, which increases the area of ​​the insulating layer 213 covered by the first active material layer 212, reduces the risk of the insulating layer 213 falling off, and is conducive to improving the connection stability of the insulating layer 213. At the same time, the area of ​​the first active material layer 212 in the overlapping area Q can be larger, which is conducive to the battery 100 having a higher energy density. By W1 / (W1+W2)≤0.5, the width of the second area 2131 of the insulating layer 213 is prevented from being too small, so that the insulating layer 213 can play a good role in reducing the risk of short circuit of the battery 100. Therefore, by 0.3≤W1 / (W1+W2)≤0.5, the connection stability of the insulating member can be improved, and the size of the second area 2131 of the insulating layer 213 not covered by the first active material layer 212 in the width direction Y of the first pole piece can be larger, so that the insulating layer 213 can play a good role in reducing the risk of short circuit of the battery 100.

[0119] In some embodiments, along the width direction Y of the first pole piece, the width of the overlapping region Q is W1 mm, the width of the second region 2131 is W2 mm, and 3≤W1+W2≤5.

[0120] For example, W1+W2 can be 3, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, etc.

[0121] By setting W1+W2≥3, the insulating layer 213 has a larger coverage area, which can better reduce the risk of burrs piercing the isolation film 23 and causing the battery cell 100 to short-circuit, thereby improving the safety performance of the battery cell 100. By setting W1+W2≤5, the influence of the insulating layer 213 on the size of the battery cell 100 can be reduced, thereby reducing the influence of the insulating layer 213 on the energy density of the battery cell 100. Therefore, by setting 3≤W1+W2≤5, the safety performance of the battery cell 100 can be improved, and the influence of the insulating layer 213 on the energy density of the battery cell 100 can be reduced, so that the battery cell 100 has a higher energy density.

[0122] In some embodiments, along the width direction Y of the first pole piece, the width of the overlapping region Q is W1 mm, 1≤W1≤2.5.

[0123] For example, W1 can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, etc. By W1≥1, the width of the overlapping area Q along the width direction Y of the first pole piece is larger, the area of ​​the insulating layer 213 covered by the first active material layer 212 is increased, the risk of the insulating layer 213 being separated from the first current collector 211 is reduced, and the connection stability of the insulating layer 213 is improved. By W1≤2.5, the influence of the insulating layer 213 on the size of the battery cell 100 can be reduced, thereby reducing the influence of the insulating layer 213 on the energy density of the battery cell 100 and reducing the influence on the rate of the battery cell 100. Therefore, by 1≤W1≤2.5, the connection stability of the insulating layer 213 can be improved, and the battery cell 100 can have a higher energy density and better rate performance.

[0124] like Figure 7 , Figure 8 As shown, in some embodiments, the third region 2132 located in the overlapping region Q is provided with a plurality of through holes 2135 , and along the thickness direction of the insulating layer 213 , the through holes 2135 penetrate two opposite sides of the third region 2132 .

[0125] When the first pole piece 21 is in the unfolded state, the thickness direction of the insulating layer 213 is parallel to the thickness direction X of the first pole piece.

[0126] The area of ​​the first surface 2111 corresponding to the through hole 2135 is not covered by the insulating layer 213 .

[0127] The first active material layer 212 may be partially contained in the through hole 2135 and connected to the first surface 2111. The shape of the through hole 2135 is not limited in the present application, for example, the through hole 2135 may be a circular hole, a triangular hole, a rectangular hole, and the like.

[0128] By setting a plurality of through holes 2135 in the third region 2132 of the insulating layer 213 located in the overlapping region Q, and the through holes 2135 penetrate the opposite sides of the third region 2132 along the thickness direction of the insulating layer 213, the electrons in the first active material layer 212 located in the overlapping region Q can reach the first current collector 211 through the through holes 2135, thereby shortening the transmission path of the electrons in the first active material layer 212 in the overlapping region Q, thereby improving the rate performance and power capacity of the battery cell 100.

[0129] In some embodiments, when viewed along the thickness direction of the third region 2132, the sum of the areas of the through holes 2135 is S1 mm. 2 , the area of ​​the third zone 2132 is Smm 2 , 0.2≤S1 / S≤0.5.

[0130] Illustratively, S1 / S may be 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.34, 0.36, 0.38, 0.4, 0.42, 0.44, 0.46, 0.48, 0.5, etc.

[0131] By setting S1 / S≥0.2, the total area of ​​all through holes 2135 is made larger, reducing the transmission power loss of electrons caused by the insulating layer 213 being set between the first active material layer 212 and the first current collector 211. By setting S1 / S≤0.5, the problem of reducing the connection area between the insulating layer 213 and the first current collector 211 due to the setting of the through holes 2135 is alleviated, and the risk of the insulating layer 213 being separated is reduced. Therefore, by setting 0.2≤S1 / S≤0.5, the transmission path of the electrons of the first active material layer 212 in the overlapping area Q can be shortened, the transmission power loss of the electrons caused by the insulating layer 213 being set between the first active material layer 212 and the first current collector 211 can be reduced, and the risk of the insulating layer 213 being separated from the first current collector 211 due to the setting of the through holes 2135 can also be reduced.

[0132] like Figure 3 , Figure 4 As shown, in some embodiments, the first pole piece 21 further includes a first pole ear 214 , which is connected to one end of the first current collector 211 along the width direction Y of the first pole piece and protrudes from one end of the second region 2131 away from the overlapping region Q.

[0133] In some embodiments, along the length direction of the first electrode sheet 21 after it is unfolded, the ratio of the size of the first electrode tab 214 to the size of the first current collector 211 is less than 0.5. Figure 3 As shown, when the first pole piece 21 is in the unfolded state, along the length direction Z of the first pole piece, the size of the first pole ear 214 is H1, and the size of the first current collector 211 is H, then H1 / H<0.5.

[0134] The first pole tab 214 may be a split pole tab, that is, the first pole tab 214 is formed by die-cutting a foil. In the case where the first pole tab 214 is a split pole tab, the first pole tab 214 may be one or more. In the embodiment where there are multiple first pole tabs 214, the multiple first pole tabs 214 are spaced apart along the length direction Z of the first pole piece. Figure 3 2 shows a situation where the first pole piece 21 is provided with a plurality of first pole tabs 214 .

[0135] In the embodiment where the first electrode tab 214 is a split electrode tab, the connecting end surface of the first electrode tab 214 and the first current collector 211 is coplanar with an end surface of the second region 2131 facing away from the overlapping region Q.

[0136] like Fig. 9 As shown, in some embodiments, the insulating layer 213 further includes a fourth region 2136 , which is connected to an end of the second region 2131 away from the overlapping region Q, and covers a portion of the surface of the first electrode 214 .

[0137] The second region 2131 , the third region 2132 , and the fourth region 2136 may be integrally formed.

[0138] The fourth region 2136 of the insulating layer 213 covers a portion of the surface of the first pole ear 214 , which helps to reduce the risk of burrs at the first pole ear 214 piercing the isolation film 23 and causing a short circuit in the battery cell 100 , and helps to improve the safety performance of the battery cell 100 .

[0139] In other embodiments, Fig.10 , Fig.11 As shown, the first electrode sheet 21 also includes a first empty foil area 215. Along the width direction Y of the first electrode sheet, the first empty foil area 215 is connected to one end of the first current collector 211 and protrudes from the end of the second area 2131 away from the overlapping area Q. Along the length direction of the unfolded first electrode sheet 21, the ratio of the length of the first empty foil area 215 to the length of the first current collector 211 is greater than or equal to 0.5 and less than or equal to 1.

[0140] When the first pole piece 21 is in the unfolded state, along the direction of the first pole piece 21, the size of the first empty foil area 215 is H1, and the size of the first current collector 211 is H, then 0.5≤H1 / H≤1. The first empty foil area 215 forms the first pole lug 214 of the first pole piece 21. This type of pole lug is a full pole lug structure, and the first empty foil area 215 will be flattened before being electrically connected to other structures.

[0141] Along the length direction of the first pole piece 21 after it is unfolded, the ratio of the length of the first empty foil area 215 to the length of the first current collector 211 is greater than or equal to 0.5, and less than or equal to 1, so that the first empty foil area 215 has a larger size in the length direction after the first pole piece 21 is unfolded, which is beneficial for the first empty foil area 215 to have better current carrying capacity and is beneficial for improving the charging rate of the battery cell 100.

[0142] like Fig.10 , Fig.11 As shown, in some embodiments, along the width direction Y of the first pole piece, the width of the first empty foil area 215 is L mm, 3≤L≤5.

[0143] L is the distance between the end of the second region 2131 away from the overlapping region Q and the end of the first empty foil region 215 farthest from the second region 2131 along the width direction Y of the first electrode sheet.

[0144] L can be 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, etc.

[0145] When L≥3, the first empty foil area 215 has a larger size in the width direction Y of the first electrode sheet, which facilitates the connection of the first empty foil area 215 with other structures, and also reduces the risk of squeezing and damaging the insulating layer 213 when the first empty foil area 215 is flattened. When L≤5, it is prevented that the first empty foil area 215 is too large in the width direction Y of the first electrode sheet, resulting in the first active material layer 212 being too small in the width direction Y of the first electrode sheet, which is beneficial for the battery cell 100 to have a higher energy density. Therefore, when 3≤L≤5, it is convenient to connect the first empty foil area 215 with other structures, reduce the risk of squeezing and damaging the insulating layer 213 when the first empty foil area 215 is flattened, and also helps the battery cell 100 to have a higher energy density.

[0146] like Fig.12 As shown, in some embodiments, the second electrode sheet 22 includes a second current collector 221 and a second active material layer 222. Along the thickness direction of the second electrode sheet 22, at least one surface of the second current collector 221 is provided with the second active material layer 222. Along the width direction of the second electrode sheet 22, both ends of the second active material layer 222 are respectively flush with both ends of the second current collector 221. Along the width direction Y of the first electrode sheet, the second active material layer 222 exceeds the overlap region Q and is close to one end of the second region 2131.

[0147] Specifically, the second electrode sheet 22 may be a negative electrode sheet, and the first electrode sheet 21 may be a positive electrode sheet. In order to reduce the risk of lithium deposition, along the width direction Y of the first electrode sheet, the second active material layer 222 exceeds both ends of the first active material layer 212 .

[0148] If the first pole piece 21 is a positive pole piece, the second pole piece 22 is a negative pole piece, and the insulating layer 213 is arranged on the positive pole piece. The insulating layer 213 can play a role of separation and insulation between the positive pole piece and the negative pole piece, thereby reducing the risk of burrs at the pole ear of the negative pole piece piercing the isolation membrane 23 and the insulating layer 213 and causing a short circuit in the battery cell 100, thereby improving the safety performance of the battery cell 100.

[0149] In this embodiment, the second active material layer 222 exceeds one end of the overlapping region Q close to the second region 2131, that is, the second active material layer 222 exceeds one end of the first active material layer 212 close to the second region 2131. Therefore, the second active material layer 222 exceeds one end of the overlapping region Q close to the second region 2131, which can reduce the risk of lithium deposition. Along the width direction Y of the first pole piece, the second active material layer 222 exceeds one end of the overlapping region Q close to the second region 2131, and the risk of the burr at the first pole ear 214 piercing the isolation film 23 and contacting the second pole piece 22 to cause a short circuit is low, and the insulating layer 213 acts as a separator between the first pole ear 214 and the second pole piece 22, thereby reducing the risk of short circuit of the battery cell 100.

[0150] like Fig.12 As shown, in some embodiments, when viewed along the thickness direction X of the first electrode sheet, the projection of one end of the second active material layer 222 along the width direction Y of the first electrode sheet is located on the insulating layer 213. According to different lengths of the second active material layer 222 beyond the overlapping region Q and close to the second region 2131, when viewed along the thickness direction X of the first electrode sheet, the projection of one end of the second active material layer 222 along the width direction Y of the first electrode sheet may be located in the second region 2131 of the insulating layer 213, or in the fourth region 2136 of the insulating layer 213.

[0151] In some embodiments, the second pole piece 22 further includes a second pole ear 223, which is connected to the second current collector 221 and protrudes from one end of the second current collector 221 along the width direction of the second pole piece 22. The second pole ear 223 protrudes from one end of the second active material layer 222 close to the second region 2131. Observing along the thickness direction X of the first pole piece, the projection of one end of the second active material layer 222 along the width direction Y of the first pole piece is located on the insulating layer 213, which can reduce the risk of the burr at the first pole ear 214 piercing the isolation film 23 and contacting the second pole piece 22 to cause a short circuit, and can also reduce the risk of the burr at the second pole ear 223 piercing the isolation film 23 and contacting the first pole piece 21 to cause a short circuit, thereby improving the safety performance of the battery cell 100.

[0152] 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.

[0153] The battery cell 100 provided in any of the above embodiments has high energy density and safety performance, which is beneficial to improving the power reliability of the electrical equipment powered by the battery cell 100 .

[0154] 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, comprising a first pole piece, wherein the first pole piece comprises a first current collector, a first active material layer and an insulating layer, and along a thickness direction of the first current collector, at least one first surface of the first current collector is provided with the first active material layer and the insulating layer; Wherein, along the thickness direction of the first electrode sheet, a portion of the first active material layer overlaps with a portion of the insulating layer to form an overlapping region, and in the overlapping region, the insulating layer is located between the first current collector and the first active material layer; Along the width direction of the first pole piece, the first active material layer includes a first area that does not overlap with the insulating layer and is located on the first surface, the insulating layer includes a second area that does not overlap with the first active material layer and is located on the first surface, and the overlapping area is located between the first area and the second area.

2. The battery cell according to claim 1, characterized in that: Along the width direction of the first pole piece, the width of the overlapping area is W1 mm, the width of the second area is W2 mm, and 0.3≤W1 / (W1+W2)≤0.

5.

3. The battery cell according to claim 1 or 2, characterized in that: Along the width direction of the first pole piece, the width of the overlapping area is W1 mm, the width of the second area is W2 mm, and 3≤W1+W2≤5.

4. The battery cell according to any one of claims 1 to 3, characterized in that: Along the width direction of the first pole piece, the width of the overlapping area is W1 mm, 1≤W1≤2.

5.

5. The battery cell according to any one of claims 1 to 4, characterized in that: The thickness of the insulating layer at any position is greater than or equal to 4 μm and less than or equal to 10 μm.

6. The battery cell according to any one of claims 1 to 5, characterized in that: The insulating layer includes a third region located in the overlapping region, and a thickness of the third region is less than or equal to a thickness of the second region.

7. The battery cell according to any one of claims 1 to 6, characterized in that: The insulating layer includes a third region located in the overlapping region, the thickness of the third region is T1 μm, the thickness of the first active material layer located in the first region is T2 μm, and 0.1≤T1 / T2≤0.

25.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The insulating layer includes a substrate and two adhesive layers, and along the thickness direction of the substrate, the two adhesive layers are respectively arranged on two opposite surfaces of the substrate, and along the width direction of the first pole piece, a part of the adhesive layer and a part of the substrate are located in the overlapping area, and another part of the adhesive layer and another part of the substrate are located in the second area; One of the two adhesive layers connects the substrate and the first current collector, and the other of the two adhesive layers connects the substrate and the first active material layer.

9. The battery cell according to claim 8, characterized in that: The thickness of the adhesive layer is T3 μm, the thickness of the substrate is T4 μm, and 0.1≤T3 / T4≤0.

25.

10. The battery cell according to any one of claims 1 to 9, characterized in that: The insulating layer includes a third region located in the overlapping region. The third region is provided with a plurality of through holes. Along the thickness direction of the insulating layer, the through holes penetrate two opposite sides of the third region.

11. The battery cell according to claim 10, characterized in that: Observed along the thickness direction of the third zone, the sum of the areas of all through holes is S1mm 2 , the area of ​​the third zone is Smm 2 , 0.2≤S1 / S≤0.

5.

12. The battery cell according to any one of claims 1 to 11, characterized in that: The first pole piece also includes a first empty foil area. Along the width direction of the first pole piece, the first empty foil area is connected to one end of the first current collector and protrudes from one end of the second area away from the overlapping area. Along the length direction of the unfolded first pole piece, the ratio of the length of the first empty foil area to the length of the first current collector is greater than or equal to 0.5 and less than or equal to 1.

13. The battery cell according to claim 12, characterized in that: Along the width direction of the first pole piece, the width of the first empty foil area is L mm, 3≤L≤5.

14. The battery cell according to any one of claims 1 to 11, characterized in that: The first pole piece further comprises a first pole ear, which is connected to one end of the first current collector along the width direction of the first pole piece and protrudes from one end of the second region away from the overlapping region, and along the length direction of the first pole piece after being unfolded, the ratio of the size of the first pole ear to the size of the first current collector is less than 0.5; The insulating layer further includes a fourth region, the fourth region is connected to an end of the second region away from the overlapping region, and the fourth region covers a portion of the surface of the first electrode tab.

15. The battery cell according to any one of claims 1 to 14, characterized in that: The insulating layer is an integrally formed structure.

16. The battery cell according to any one of claims 1 to 7, characterized in that: The insulating layer is adhesive tape or insulating coating.

17. The battery cell according to any one of claims 1 to 16, characterized in that: The battery cell also includes a second pole piece. The first pole piece and the second pole piece have opposite polarities. The second pole piece includes a second active material layer. Along the width direction of the first pole piece, the second active material layer exceeds the overlapping area and is close to one end of the second area.

18. The battery cell according to any one of claims 1 to 17, characterized in that: Therefore, the first electrode is the positive electrode.

19. An electrical equipment, characterized in that: Comprising a battery cell according to any one of claims 1-18.

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