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 is formed by winding a positive pole piece, a diaphragm and a negative pole piece which are stacked, and the outermost circle of pole piece is the positive pole piece; the positive pole piece comprises a double-sided coating area, a single-sided coating area and a double-sided empty foil area which are sequentially arranged from the winding starting end to the winding ending end; the first adhesive tape of the battery cell is attached to one side, which is not provided with the active material layer, of the single-side coating area, and at least part of the first adhesive tape is arranged on a second circle of positive pole piece of the battery cell from outside to inside; in the winding direction, the first gummed paper exceeds the first edge, away from the single-face coating area, of the double-face empty foil area; and the first gummed paper exceeds the second edge and the third edge of the double-sided empty foil area along the winding axis direction. And the capacity of the battery core is less than 3Ah. The possibility of short circuit caused by contact between the edge of the double-sided empty foil area and the negative pole piece is reduced, and the safety of the battery cell is improved; and the first gummed paper does not increase the thickness of the battery cell, so that the energy density of the battery cell can be 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, batteries have been widely used in electronic equipment, electric vehicles, electric two-wheelers, power tools, etc. The requirements for battery quality, safety, and miniaturization are becoming increasingly higher.

[0003] In a wound cell, adhesive tape is usually placed at the head and tail of the wound electrode assembly, which can improve the drop test pass rate of the cell, but will increase the thickness of the cell and affect the energy density of the cell. If the adhesive tape at the head and tail of the electrode assembly is removed, the tail end of the electrode assembly is prone to short circuit, affecting the safety of the cell. Summary of the invention

[0004] The present application provides a battery cell and an electrical device, which can improve the energy density of the battery cell.

[0005] In the first aspect, the present application provides a battery cell, which includes an electrode assembly, which is formed by winding a stacked positive electrode sheet, a separator and a negative electrode sheet, and the outermost electrode sheet of the electrode assembly is a positive electrode sheet; the positive electrode sheet includes a double-sided coating area, a single-sided coating area and a double-sided empty foil area arranged in sequence from the starting end to the ending end of the winding; the battery cell also includes a first adhesive tape, the first adhesive tape is attached to the side of the single-sided coating area where the active material layer is not provided, and the first adhesive tape is at least partially provided on the positive electrode sheet of the second circle of the battery cell from the outside to the inside; along the winding direction, the double-sided empty foil area has a first edge away from the single-sided coating area, and the first adhesive tape exceeds the first edge; along the winding axis direction, the double-sided empty foil area has a second edge and a third edge opposite to each other, and the first adhesive tape exceeds the second edge and the third edge, and the battery cell capacity is less than 3Ah.

[0006] In the above technical scheme, the first adhesive tape is attached to the side of the single-sided coating area where the active material layer is not provided; along the winding direction, the double-sided empty foil area has a first edge away from the single-sided coating area, and the first adhesive tape exceeds the first edge, so that along the winding direction, the first adhesive tape can isolate the first edge of the double-sided empty foil area from the negative electrode sheet, reducing the possibility of short-circuiting between the first edge of the double-sided empty foil area and the negative electrode sheet, thereby improving the safety of the battery cell; along the winding axis direction, the double-sided empty foil area has opposite second and third edges, and the first adhesive tape exceeds the second and third edges, so that along the winding axis direction, the first adhesive tape can isolate the second and third edges of the double-sided empty foil area from the negative electrode sheet, reducing the possibility of short-circuiting between the second and third edges of the double-sided empty foil area and the negative electrode sheet, thereby improving the safety of the battery cell; and the adhesive tape at the head and tail of the middle electrode assembly in the small-capacity battery cell can be eliminated, and the first adhesive tape will not increase the thickness of the battery cell, which can be beneficial to improving the energy density of the battery cell. At the same time, when the capacity of the battery cell is less than 3Ah, because the battery with smaller capacity has lower weight, even if the glue wrapping is cancelled, the possibility of failure when falling is lower.

[0007] In some embodiments of the present application, the first adhesive tape includes a first part and a second part, the first part is attached to the double-sided coating area, and the second part is attached to the single-sided coating area.

[0008] In the above technical scheme, due to the inevitable errors in the preparation process, if the first adhesive tape is entirely set on the single-sided coating area of ​​the positive electrode plate, there may be a gap between the first adhesive tape and the double-sided coating area, resulting in a short circuit between the positive electrode plate and the negative electrode plate. Therefore, by making the first adhesive tape include a first part and a second part, the first part is attached to the double-sided coating area, and the second part is attached to the single-sided coating area, so that the first adhesive tape can cover one end of the single-sided coating area close to the double-sided coating area, thereby reducing the risk of short circuit between the positive electrode plate and the negative electrode plate, thereby improving the safety of the battery cell.

[0009] In some embodiments of the present application, along the winding axis direction, the length of the second part is L1, and the length of the double-sided empty foil area is L2, satisfying L1>L2; along the winding direction, the width of the second part is W1, and the width of the double-sided empty foil area is W2, satisfying W1>W2; observed along the radial direction of the winding, the second part completely covers the double-sided empty foil area.

[0010] In the above technical scheme, the length L1 of the second part and the length L2 of the double-sided empty foil area along the winding axis direction satisfy L1>L2; along the winding direction, the width of the second part is W1, and the width of the double-sided empty foil area is W2, satisfying W1>W2; observed along the radial direction of winding, the second part completely covers the double-sided empty foil area; the second part can cover the double-sided empty foil area along the winding axis direction and along the winding direction. The covering of the double-sided empty foil area here refers to covering the side of the double-sided empty foil area opposite to the second part, thereby reducing the possibility of short circuit between the double-sided empty foil area and the negative electrode sheet, thereby improving the safety of the battery cell.

[0011] In some embodiments of the present application, 0<L1-L2≤10mm.

[0012] In the above technical scheme, when L1-L2 is greater than 0, the second part can cover the double-sided empty foil area along the winding axis direction, thereby reducing the possibility of short circuit between the double-sided empty foil area and the negative electrode sheet, and improving the safety of the battery cell; when L1-L2 is less than or equal to 10mm, the length of the part of the second part that exceeds the positive electrode sheet along the winding axis direction is shorter, which can reduce the possibility of interference between the first adhesive tape and other components of the battery cell, facilitate the part of the second part that exceeds the positive electrode sheet to be attached to the head and / or tail of the electrode assembly, and save the material of the first adhesive tape; therefore, when 0<L1-L2≤10mm, the second part can cover the double-sided empty foil area along the winding axis direction, thereby reducing the possibility of short circuit between the double-sided empty foil area and the negative electrode sheet, and improving the safety of the battery cell, and can reduce the possibility of interference between the first adhesive tape and other components of the battery cell, facilitate the part of the second part that exceeds the positive electrode sheet to be attached to the head and / or tail of the electrode assembly, and save the material of the first adhesive tape.

[0013] In some embodiments of the present application, along the winding direction, the width of the first portion is W3, satisfying 0<W3≤10mm.

[0014] In the above technical solution, due to the unavoidable error of the preparation process, if the first adhesive tape is entirely set on the single-sided coating area of ​​the positive electrode sheet (i.e., W3=0), there may be a gap between the first adhesive tape and the double-sided coating area, resulting in a short circuit between the positive electrode sheet and the negative electrode sheet. Therefore, by making W3 greater than 0, the first part is attached to the double-sided coating area, and the second part is attached to the single-sided coating area, so that the first adhesive tape can cover one end of the single-sided coating area close to the double-sided coating area, thereby reducing the risk of short circuit between the positive electrode sheet and the negative electrode sheet and improving the safety of the battery cell; when W3 is less than or equal to 10 mm, the overlapping area of ​​the first adhesive tape and the double-sided coating area is less than 0. The area is small, the possibility of the first adhesive tape interfering with other components on the double-sided coating area is small, and the influence of the first adhesive tape on the thickness of the battery cell is small, which is beneficial to improving the energy density of the battery cell and can save the material of the first adhesive tape; therefore, when 0<W3≤10mm, the first adhesive tape can cover the end of the single-sided coating area close to the double-sided coating area, thereby reducing the risk of short circuit between the positive electrode plate and the negative electrode plate and improving the safety of the battery cell, and the possibility of the first adhesive tape interfering with other components on the double-sided coating area is small, and the influence of the first adhesive tape on the thickness of the battery cell is small, which is beneficial to improving the energy density of the battery cell and can save the material of the first adhesive tape.

[0015] In some embodiments of the present application, a portion of the double-sided empty foil area is located on one side of the electrode assembly along its thickness direction, and another portion of the double-sided empty foil area is located on one side of the electrode assembly along the first direction; the first direction, the winding axis direction, and the thickness direction of the electrode assembly are perpendicular to each other.

[0016] In the above technical solution, by making a part of the double-sided empty foil area located on one side of the electrode assembly along its thickness direction, and the other part of the double-sided empty foil area located on one side of the electrode assembly along the first direction, after the electrode assembly is wound and formed, the double-sided empty foil area only occupies the space on one side of the electrode assembly along its thickness direction and one side along the first direction, and will not extend to other sides of the electrode assembly, so that the double-sided empty foil area has less effect on the thickness of the electrode assembly, which is beneficial to improving the energy density of the battery cell.

[0017] In some embodiments of the present application, the first adhesive tape includes a base layer and a first adhesive layer, and the first adhesive layer is arranged on a side of the base layer facing the single-sided coating area.

[0018] In the above technical solution, the first adhesive tape includes a base layer and a first adhesive layer, and the first adhesive layer is arranged on the side of the base layer facing the single-sided coating area, so that the first adhesive layer can be bonded to the single-sided coating area, and the connection strength between the first adhesive tape and the single-sided coating area is relatively high. The first adhesive tape is not easy to separate from the single-sided coating area, so as to maintain the insulation between the positive electrode sheet and the negative electrode sheet, thereby improving the safety of the battery cell.

[0019] In some embodiments of the present application, the first adhesive tape includes a second adhesive layer, and the second adhesive layer is arranged on a side of the base layer facing away from the single-sided coating area.

[0020] In the above technical solution, by making the first adhesive tape include a second adhesive layer, the second adhesive layer is arranged on the side of the base layer facing away from the single-sided coated area, so that the second adhesive layer can be bonded to the double-sided empty foil area, thereby playing a role in fixing the double-sided empty foil area, reducing the possibility of displacement of the double-sided empty foil area relative to the single-sided coated area, thereby reducing the possibility of short circuit between the double-sided empty foil area and the negative electrode plate, and improving the safety of the battery cell.

[0021] In some embodiments of the present application, the thickness of the base layer is H1, satisfying 4μm≤H1≤20μm; the thickness of the first adhesive layer is H2, satisfying 2μm≤H2≤10μm; the thickness of the second adhesive layer is H3, satisfying 1μm≤H3≤5μm.

[0022] In the above technical scheme, when H1 is greater than or equal to 4μm, the supporting force of the base layer can be stronger, and the first adhesive tape is not easily deformed, thereby reducing the possibility of short circuit between the positive electrode sheet and the negative electrode sheet due to deformation of the first adhesive tape, thereby improving the safety of the battery cell; when H1 is less than or equal to 20μm, the base layer can have less influence on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell; therefore, when 4μm≤H1≤20μm, the supporting force of the base layer can be stronger, and the first adhesive tape is not easily deformed, thereby reducing the possibility of short circuit between the positive electrode sheet and the negative electrode sheet due to deformation of the first adhesive tape, thereby improving the safety of the battery cell, and the base layer can have less influence on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell.

[0023] When H2 is greater than or equal to 2μm, the adhesion force of the first adhesive layer can be higher, the connection strength between the first adhesive tape and the single-sided coating area can be higher, and the first adhesive tape is not easy to separate from the single-sided coating area to maintain the insulation between the positive electrode sheet and the negative electrode sheet, so that the safety of the battery cell is higher, and the first adhesive tape has a better binding effect on the metal ions in the coating area, reducing the possibility of metal ion precipitation, which is beneficial to extending the service life of the battery cell; when H2 is less than or equal to 10μm, the first adhesive layer can have less effect on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell; therefore, when 2μm≤H2≤10μm, the adhesion force of the first adhesive layer can be higher, the connection strength between the first adhesive tape and the single-sided coating area can be higher, and the first adhesive tape is not easy to separate from the single-sided coating area to maintain the insulation between the positive electrode sheet and the negative electrode sheet, so that the safety of the battery cell is higher, and the first adhesive tape has a better binding effect on the metal ions in the coating area, reducing the possibility of metal ion precipitation, which is beneficial to extending the service life of the battery cell, and the first adhesive layer can have less effect on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell.

[0024] When H3 is greater than or equal to 1μm, the adhesion force of the second adhesive layer can be higher, the connection strength between the first adhesive tape and the double-sided empty foil area can be higher, the possibility of displacement of the double-sided empty foil area relative to the single-sided coated area can be reduced, thereby reducing the possibility of short circuit between the double-sided empty foil area and the negative electrode sheet, which can improve the safety of the battery cell; when H3 is less than or equal to 5μm, the second adhesive layer can have less effect on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell; therefore, when 1μm≤H3≤5μm, the adhesion force of the second adhesive layer can be higher, the connection strength between the first adhesive tape and the double-sided empty foil area can be higher, the possibility of displacement of the double-sided empty foil area relative to the single-sided coated area can be reduced, thereby reducing the possibility of short circuit between the double-sided empty foil area and the negative electrode sheet, which can improve the safety of the battery cell, and the second adhesive layer can have less effect on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell.

[0025] In some embodiments of the present application, the base layer includes polyethylene terephthalate material and / or polyimide material, the first adhesive layer includes polyolefin material and / or rubber material, and the second adhesive layer includes polyolefin material and / or rubber material.

[0026] In the above technical solution, by making the base layer include polyethylene terephthalate material and / or polyimide material, the supporting force of the base layer can be made stronger, and the first adhesive tape is not easy to deform, thereby reducing the possibility of short circuit between the positive electrode plate and the negative electrode plate due to deformation of the first adhesive tape, thereby improving the safety of the battery cell.

[0027] By making the first adhesive layer include polyolefin material and / or rubber material, the adhesion force of the first adhesive layer can be made higher, the connection strength between the first adhesive tape and the single-sided coating area can be made higher, and the first adhesive tape is not easy to separate from the single-sided coating area, so as to maintain the insulation between the positive electrode plate and the negative electrode plate, so that the safety of the battery cell is higher; and the first adhesive layer has strong corrosion resistance, which can reduce the risk of short circuit between the positive electrode plate and the negative electrode plate after the first adhesive layer is corroded by the electrolyte, thereby further improving the safety of the battery cell.

[0028] By making the second adhesive layer include polyolefin material and / or rubber material, the adhesion force of the second adhesive layer can be made higher, the connection strength between the first adhesive tape and the double-sided empty foil area can be made higher, and the possibility of displacement of the double-sided empty foil area relative to the single-sided coated area can be reduced, thereby reducing the possibility of short circuit between the double-sided empty foil area and the negative electrode plate, which can improve the safety of the battery cell; and the second adhesive layer has strong corrosion resistance, which can reduce the risk of short circuit between the positive electrode plate and the negative electrode plate after the second adhesive layer is corroded by the electrolyte, thereby further improving the safety of the battery cell.

[0029] In some embodiments of the present application, the battery cell includes a second adhesive tape, which is used to fix the winding tail end of the positive electrode sheet; the battery cell includes a positive electrode tab and a third adhesive tape, the positive electrode tab is connected to the positive electrode sheet, a portion of the third adhesive tape is attached to the positive electrode tab, and another portion is attached to the positive electrode sheet, and along the thickness direction of the electrode assembly, the projection of the second adhesive tape does not overlap with the projection of the third adhesive tape; the battery cell includes a negative electrode tab and a fourth adhesive tape, the negative electrode tab is connected to the negative electrode sheet, a portion of the fourth adhesive tape is attached to the negative electrode tab, and another portion is attached to the negative electrode sheet, and along the thickness direction of the electrode assembly, the projection of the second adhesive tape does not overlap with the projection of the fourth adhesive tape.

[0030] In the above technical scheme, by making the battery cell include a second adhesive tape, the second adhesive tape is used to fix the winding tail end of the positive electrode sheet, which can further reduce the possibility of displacement of the double-sided empty foil area of ​​the positive electrode sheet relative to the single-sided coated area, thereby reducing the possibility of short circuit between the double-sided empty foil area and the negative electrode sheet, and improving the safety of the battery cell; by making a part of the third adhesive tape attached to the positive electrode ear and the other part attached to the positive electrode sheet, along the thickness direction of the electrode assembly, the projection of the second adhesive tape does not overlap with the projection of the third adhesive tape; a part of the fourth adhesive tape is attached to the negative electrode ear and the other part is attached to the negative electrode sheet, along the thickness direction of the electrode assembly, the projection of the second adhesive tape does not overlap with the projection of the fourth adhesive tape, so that in the thickness direction of the electrode assembly, the thickness of the second adhesive tape does not overlap with the thickness of the third adhesive tape and the thickness of the fourth adhesive tape, which is beneficial to reducing the thickness of the battery cell and improving the energy density of the battery cell.

[0031] In some embodiments of the present application, the battery cell includes a fifth adhesive tape, which is attached to a side of the double-sided empty foil area facing the winding center of the electrode assembly.

[0032] In the above technical solution, by making the battery cell also include the fifth adhesive tape, the fifth adhesive tape is attached to the side of the double-sided empty foil area facing the winding center of the electrode assembly, so that the fifth adhesive tape can play the role of insulating the double-sided empty foil area and the negative electrode plate, thereby reducing the possibility of short circuit between the positive electrode plate and the negative electrode plate, and improving the safety of the battery cell.

[0033] In some embodiments of the present application, the first adhesive tape is at least partially disposed on the negative electrode plate of the second circle from the outside to the inside of the battery cell.

[0034] In the above technical solution, the first adhesive tape is attached to the negative electrode plate of the second circle from the outside to the inside of the battery cell; along the winding direction, the first adhesive tape exceeds the first edge, so that along the winding direction, the first adhesive tape can isolate the first edge of the double-sided empty foil area from the negative electrode plate, thereby reducing the possibility of short circuit between the first edge of the double-sided empty foil area and the negative electrode plate, thereby improving the safety of the battery cell.

[0035] In a second aspect, the present application provides an electrical device, comprising a battery cell as described above, wherein the battery cell is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 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 also be obtained based on these drawings.

[0037] Figure 1 A schematic cross-sectional view of an electrode assembly of a battery cell provided in some embodiments of the present application;

[0038] Figure 2 A schematic diagram of the structure of a positive electrode sheet of a battery cell after unfolding provided in some embodiments of the present application;

[0039] Figure 3 A schematic structural diagram of an electrode assembly of a battery cell provided in some embodiments of the present application from one perspective;

[0040] Figure 4 A schematic diagram of the structure of the first adhesive tape of the battery cell provided in some embodiments of the present application.

[0041] Icons: 10-battery cell; 100-electrode assembly; 110-positive electrode plate; 111-double-sided coating area; 112-single-sided coating area; 113-double-sided empty foil area; 120-diaphragm; 130-negative electrode plate; 210-first adhesive tape; 211-first part; 212-second part; 210a-base layer; 210b-first adhesive layer; 210c-second adhesive layer; 220-second adhesive tape; 230-third adhesive tape; 240-fourth adhesive tape; 250-fifth adhesive tape; 310-positive electrode tab; 320-negative electrode tab; X-winding axis direction; Y-first direction; Z-thickness direction of the electrode assembly. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly 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. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of this application.

[0043] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0044] The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0045] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0046] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0047] With the development of the new energy industry, batteries are gradually developing in the direction of high energy density and high power density. At present, in the wound structure battery cells, adhesive tape is set on the head (the end of the battery cell with the positive and negative pole ears) and the tail (the end corresponding to the head along the length direction of the battery cell) of the electrode assembly after winding to improve the drop test pass rate of the battery cell. However, some usage scenarios have low or even no requirements for the drop test pass rate of the battery cell. The adhesive tape on the head and tail of the electrode assembly will become a redundant design, and will increase the thickness of the battery cell, affecting the energy density of the battery cell. However, if the adhesive tape on the head and tail of the electrode assembly is directly removed, the winding tail end of the outermost pole piece of the electrode assembly is prone to displacement, resulting in short circuit between the two pole pieces with opposite polarities, affecting the safety of the battery cell.

[0048] In order to improve the energy density of a battery cell, the present application provides a battery cell, which includes an electrode assembly, which is formed by winding a stacked positive electrode sheet, a separator and a negative electrode sheet, and the outermost electrode sheet of the electrode assembly is a positive electrode sheet; the positive electrode sheet includes a double-sided coating area, a single-sided coating area and a double-sided empty foil area arranged in sequence from the starting end to the ending end of the winding; the battery cell also includes a first adhesive tape, which is attached to a side of the single-sided coating area where an active material layer is not provided; along the winding direction, the double-sided empty foil area has a first edge away from the single-sided coating area, and the first adhesive tape exceeds the first edge; along the winding axis direction, the double-sided empty foil area has a second edge and a third edge opposite to each other, and the first adhesive tape exceeds the second edge and the third edge.

[0049] In a battery cell of this structure, the first adhesive tape is attached to the side of the single-sided coated area where the active material layer is not provided; along the winding direction, the double-sided empty foil area has a first edge away from the single-sided coated area, and the first adhesive tape exceeds the first edge, so that along the winding direction, the first adhesive tape can isolate the first edge of the double-sided empty foil area from the negative electrode sheet, reducing the possibility of the first edge of the double-sided empty foil area contacting and short-circuiting with the negative electrode sheet, thereby improving the safety of the battery cell; along the winding axis direction, the double-sided empty foil area has opposite second and third edges, and the first adhesive tape exceeds the second and third edges, so that along the winding axis direction, the first adhesive tape can isolate the second and third edges of the double-sided empty foil area from the negative electrode sheet, reducing the possibility of the second and third edges of the double-sided empty foil area contacting and short-circuiting with the negative electrode sheet, thereby improving the safety of the battery cell; and since the adhesive tapes at the head and tail of the electrode assembly are eliminated and the first adhesive tape does not increase the thickness of the battery cell, it can be beneficial to improve the energy density of the battery cell.

[0050] The battery cell provided in the embodiment of the present application can be a secondary battery or a primary battery, for example, a lithium ion battery, a sodium ion battery or a magnesium ion battery, etc., which is not limited in the embodiment of the present application. The battery cell can be cylindrical, flat, rectangular or other shapes, etc., which is not limited in the embodiment of the present application.

[0051] The embodiments of the present application provide an electrical device that uses a battery cell as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, and the like.

[0052] See also Figures 1 to 3 , Figure 1 A schematic cross-sectional view of an electrode assembly of a battery cell provided in some embodiments of the present application; Figure 2 A schematic diagram of the structure of a positive electrode sheet of a battery cell after unfolding provided in some embodiments of the present application; Figure 3 A schematic structural diagram of an electrode assembly of a battery cell provided in some embodiments of the present application from one perspective.

[0053] In some embodiments, the battery cell includes a shell, an electrode assembly 100 and an electrolyte, and the shell is used to contain the electrode assembly 100 and the electrolyte. The electrode assembly 100 is composed of a positive electrode sheet 110, a negative electrode sheet 130 and a separator 120. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet 110 and the negative electrode sheet 130 to work. The positive electrode sheet 110 includes a positive electrode collector and a positive electrode active material layer, and the positive electrode active material layer is coated on the surface of the positive electrode collector. The part of the positive electrode collector that is not coated with the positive electrode active material layer is used as a positive electrode ear 310 to realize the input or output of electric energy of the positive electrode sheet 110 through the positive electrode ear 310. The positive electrode ear and the positive electrode collector can also be set separately and then connected as one, such as the positive electrode ear and the positive electrode collector are connected as one by welding connection, conductive glue connection, etc. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary material or lithium manganese oxide. The negative electrode plate 130 includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode current collector, and the part of the negative electrode current collector not coated with the negative electrode active material layer serves as a negative electrode tab 320, so as to realize the input or output of electric energy of the negative electrode plate 130 through the negative electrode tab 320. The negative electrode tab and the negative electrode current collector can also be separately arranged and then connected as a whole, for example, the negative electrode tab and the negative electrode current collector are connected as a whole by welding connection, conductive adhesive connection, etc. The material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon material or silicon material, etc. The material of the diaphragm 120 can be polypropylene (PP) or polyethylene (PE), etc. The electrolyte can include an organic solvent, an electrolyte lithium salt, etc.

[0054] The embodiment of the present application provides a battery cell, and the battery cell capacity is less than 3Ah. The battery cell includes an electrode assembly 100, and the electrode assembly 100 is wound by stacking a positive electrode sheet 110, a separator 120, and a negative electrode sheet 130, and the outermost electrode sheet of the electrode assembly 100 is the positive electrode sheet 110. The positive electrode sheet 110 includes a double-sided coating area 111, a single-sided coating area 112, and a double-sided empty foil area 113 arranged in sequence from the starting end to the end of the winding. The battery cell also includes a first adhesive tape 210, which is attached to the side of the single-sided coating area 112 where the active material layer is not provided, and is at least partially provided on the positive electrode sheet 110 of the second circle from the outside to the inside of the battery cell. Along the winding direction, the double-sided empty foil area 113 has a first edge 1131 away from the single-sided coating area 112, and the first adhesive tape 210 exceeds the first edge 1131. Along the winding axis direction X, the double-sided empty foil area 113 has opposite second edges 1132 and third edges 1133, and the first adhesive tape 210 exceeds the second edge 1132 and the third edge 1133. The second circle of positive electrode sheets 110 from the outside to the inside refers to the positive electrode sheets 110 adjacent to the outermost circle of sheets. When the cell capacity is less than 3Ah, the battery with a smaller capacity has a lower weight, so the possibility of failure when falling is lower.

[0055] In some embodiments, the positive electrode sheet 110 includes a positive current collector 110a, a first positive active material layer 110b, and a second positive active material layer 110c, wherein the first positive active material layer 110b and the second positive active material layer 110c are respectively disposed on both sides of the positive current collector 110a along its thickness direction. The double-sided coating area 111 is an area where both sides of the positive current collector 110a along its thickness direction are coated with positive active material layers, that is, an area where both sides of the positive current collector 110a along its thickness direction are covered by the first positive active material layer 110b and the second positive active material layer 110c. The single-sided coating area 112 is an area where one side of the positive current collector 110a along its thickness direction is coated with a positive active material layer, that is, an area where one side of the positive current collector 110a along its thickness direction is covered by the first positive active material layer 110b, and the other side is not covered by the second positive active material layer 110c. The double-sided empty foil area 113 is an area where the positive electrode current collector 110a is not coated with the positive electrode active material layer on both sides along its thickness direction, that is, an area where both sides of the positive electrode current collector 110a are not covered by the first positive electrode active material layer 110b and the second positive electrode active material layer 110c along its thickness direction.

[0056] By making the first adhesive tape 210 attached to the side of the single-sided coated area 112 where the active material layer is not provided; along the winding direction, the double-sided empty foil area 113 has a first edge 1131 away from the single-sided coated area 112, and the first adhesive tape 210 exceeds the first edge 1131, so that along the winding direction, the first adhesive tape 210 can isolate the first edge 1131 of the double-sided empty foil area 113 from the negative electrode sheet 130, reducing the possibility of short circuit between the first edge 1131 of the double-sided empty foil area 113 and the negative electrode sheet 130, thereby improving the safety of the battery cell; by making the double-sided empty foil area 113 have a second edge 1131 opposite to the first edge 1131 of the double-sided empty foil area 113 along the winding axis direction X. 1132 and the third edge 1133, the first adhesive tape 210 exceeds the second edge 1132 and the third edge 1133, so that along the winding axis direction X, the first adhesive tape 210 can isolate the second edge 1132 and the third edge 1133 of the double-sided empty foil area 113 from the negative electrode plate 130, reducing the possibility of short circuit between the second edge 1132 and the third edge 1133 of the double-sided empty foil area 113 and the negative electrode plate 130, thereby improving the safety of the battery cell; and since the adhesive tape at the head and tail of the electrode assembly 100 is eliminated and the first adhesive tape 210 does not increase the thickness of the battery cell, it can be beneficial to improve the energy density of the battery cell.

[0057] In some embodiments, the first adhesive tape 210 is at least partially disposed on the negative electrode plate 130 of the second circle from the outside to the inside of the battery cell.

[0058] By attaching the first adhesive tape 210 to the negative electrode sheet 130 of the second circle from the outside to the inside of the battery cell; along the winding direction, the first adhesive tape 210 exceeds the first edge, so that along the winding direction, the first adhesive tape 210 can isolate the first edge of the double-sided empty foil area 113 from the negative electrode sheet 130, reducing the possibility of short circuit between the first edge of the double-sided empty foil area 113 and the negative electrode sheet 130, thereby improving the safety of the battery cell. In some embodiments, the first adhesive tape 210 includes a first portion 211 and a second portion 212, the first portion 211 is attached to the double-sided coating area 111, and the second portion 212 is attached to the single-sided coating area 112.

[0059] Due to the inevitable errors in the preparation process, if the first adhesive tape 210 is entirely set on the single-sided coating area 112 of the positive electrode plate 110, there may be a gap between the first adhesive tape 210 and the double-sided coating area 111, resulting in a short circuit between the positive electrode plate 110 and the negative electrode plate 130. Therefore, by making the first adhesive tape 210 include a first part 211 and a second part 212, the first part 211 is attached to the double-sided coating area 111, and the second part 212 is attached to the single-sided coating area 112, so that the first adhesive tape 210 can cover the end of the single-sided coating area 112 close to the double-sided coating area 111, thereby reducing the risk of short circuit between the positive electrode plate 110 and the negative electrode plate 130, thereby improving the safety of the battery cell.

[0060] In some embodiments, along the winding axis direction X, the length of the second portion 212 is L1, and the length of the double-sided empty foil area 113 is L2, satisfying L1>L2. For example, L1 can be 1.1*L2, 1.2*L2, or 1.5*L2, etc. Along the winding direction, the width of the second portion 212 is W1, and the width of the double-sided empty foil area 113 is W2, satisfying W1>W2. For example, W1 can be 1.1*W2, 1.2*W2, or 1.5*W2, etc. Observed along the radial direction of winding, the second portion 212 completely covers the double-sided empty foil area 113.

[0061] By making the length L1 of the second part 212 and the length L2 of the double-sided empty foil area 113 along the winding axis direction X satisfy L1>L2; along the winding direction, the width of the second part 212 is W1, and the width of the double-sided empty foil area 113 is W2, satisfying W1>W2; observed along the radial direction of winding, the second part 212 completely covers the double-sided empty foil area 113; so that along the winding axis direction X and along the winding direction, the second part 212 can cover the double-sided empty foil area 113, and the covering of the double-sided empty foil area 113 mentioned here refers to covering the side of the double-sided empty foil area 113 opposite to the second part 212, thereby reducing the possibility of short circuit between the double-sided empty foil area 113 and the negative electrode sheet 130, thereby improving the safety of the battery cell.

[0062] In some embodiments, 0<L1-L2≤10mm. For example, L1-L2 can be 1mm, 5mm or 10mm.

[0063] When L1-L2 is greater than 0, the second portion 212 can cover the double-sided empty foil area 113 along the winding axis direction X, thereby reducing the possibility of short circuit between the double-sided empty foil area 113 and the negative electrode sheet 130, and improving the safety of the battery cell; when L1-L2 is less than or equal to 10 mm, the length of the portion of the second portion 212 that exceeds the positive electrode sheet 110 along the winding axis direction X is shorter, which can reduce the possibility of interference between the first adhesive tape 210 and other components of the battery cell, and facilitate the portion of the second portion 212 that exceeds the positive electrode sheet 110 to be attached to the head and / or tail, and can save the material of the first adhesive tape 210; therefore, when 0<L1-L2≤10mm, the second part 212 can cover the double-sided empty foil area 113 along the winding axis direction X, thereby reducing the possibility of short circuit between the double-sided empty foil area 113 and the negative electrode sheet 130, thereby improving the safety of the battery cell, and can reduce the possibility of interference between the first adhesive tape 210 and other components of the battery cell, so that the part of the second part 212 exceeding the positive electrode sheet 110 is attached to the head and / or tail of the electrode assembly 100, and can save the material of the first adhesive tape 210.

[0064] In some embodiments, along the winding direction, the width of the first portion 211 is W3, satisfying 0<W3≤10 mm. For example, W3 may be 1 mm, 6 mm, or 10 mm.

[0065] Since the error of the preparation process is inevitable, if the first adhesive tape 210 is set entirely on the single-sided coating area 112 of the positive electrode sheet 110 (i.e., W3=0), there may be a gap between the first adhesive tape 210 and the double-sided coating area 111, resulting in a short circuit between the positive electrode sheet 110 and the negative electrode sheet 130. Therefore, by making W3 greater than 0, the first part 211 is attached to the double-sided coating area 111, and the second part 212 is attached to the single-sided coating area 112, so that the first adhesive tape 210 can cover the end of the single-sided coating area 112 close to the double-sided coating area 111, thereby reducing the risk of short circuit between the positive electrode sheet 110 and the negative electrode sheet 130, and improving the safety of the battery cell; when W3 is less than or equal to 10mm, the gap between the first adhesive tape 210 and the double-sided coating area 111 is greater than 0, so that the gap between the first adhesive tape 210 and the double-sided coating area 111 is less ... The overlapping area is small, and the possibility of the first adhesive tape 210 interfering with other components on the double-sided coating area 111 is small. The first adhesive tape 210 has little effect on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell and can save the material of the first adhesive tape 210; therefore, when 0<W3≤10mm, the first adhesive tape 210 can cover the end of the single-sided coating area 112 close to the double-sided coating area 111, thereby reducing the risk of short circuit between the positive electrode plate 110 and the negative electrode plate 130 and improving the safety of the battery cell, and the first adhesive tape 210 can be less likely to interfere with other components on the double-sided coating area 111, and the first adhesive tape 210 has little effect on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell and can save the material of the first adhesive tape 210.

[0066] In some embodiments, a portion of the double-sided empty foil area 113 is located on one side of the electrode assembly 100 along its thickness direction Z, and another portion of the double-sided empty foil area 113 is located on one side of the electrode assembly 100 along the first direction Y.

[0067] In some embodiments, the first direction Y, the winding axis direction X, and the thickness direction Z of the electrode assembly are perpendicular to each other.

[0068] By making a portion of the double-sided empty foil area 113 located on one side of the electrode assembly 100 along its thickness direction, and the other portion of the double-sided empty foil area 113 located on one side of the electrode assembly 100 along the first direction Y, after the electrode assembly 100 is wound and formed, the double-sided empty foil area 113 only occupies the space on one side of the electrode assembly 100 along its thickness direction and one side along the first direction Y, and will not extend to other sides of the electrode assembly 100, so that the double-sided empty foil area 113 has less effect on the thickness of the electrode assembly 100, which is beneficial to improving the energy density of the battery cell.

[0069] See also Figure 4 , Figure 4 A schematic diagram of the structure of the first adhesive tape of the battery cell provided in some embodiments of the present application.

[0070] In some embodiments, the first adhesive tape 210 includes a base layer 210 a and a first adhesive layer 210 b , and the first adhesive layer 210 b is disposed on a side of the base layer 210 a facing the single-sided coating area 112 .

[0071] By making the first adhesive tape 210 include a base layer 210a and a first adhesive layer 210b, the first adhesive layer 210b is arranged on the side of the base layer 210a facing the single-sided coating area 112, so that the first adhesive layer 210b can be bonded to the single-sided coating area 112, the connection strength between the first adhesive tape 210 and the single-sided coating area 112 is relatively high, and the first adhesive tape 210 is not easy to separate from the single-sided coating area 112, so as to maintain the insulation between the positive electrode plate 110 and the negative electrode plate 130, so that the safety of the battery cell is relatively high.

[0072] In some embodiments, the first adhesive tape 210 includes a second adhesive layer 210 c , and the second adhesive layer 210 c is disposed on a side of the base layer 210 a that is away from the single-sided coating area 112 .

[0073] By making the first adhesive tape 210 include the second adhesive layer 210c, the second adhesive layer 210c is arranged on the side of the base layer 210a facing away from the single-sided coated area 112, so that the second adhesive layer 210c can be bonded to the double-sided empty foil area 113, thereby fixing the double-sided empty foil area 113, reducing the possibility of displacement of the double-sided empty foil area 113 relative to the single-sided coated area 112, thereby reducing the possibility of short circuit between the double-sided empty foil area 113 and the negative electrode plate 130, and improving the safety of the battery cell.

[0074] In other embodiments, the first adhesive tape 210 may include only one adhesive layer, one side of the adhesive layer is bonded to the single-sided coated area 112, and the other side is bonded to the double-sided empty foil area 113, which can make the thickness of the first adhesive tape 210 smaller and help improve the energy density of the battery cell.

[0075] In some embodiments, the thickness of the base layer 210 a is H1, which satisfies 4 μm≤H1≤20 μm. For example, H1 may be 4 μm, 12 μm, or 20 μm.

[0076] When H1 is greater than or equal to 4μm, the supporting force of the base layer 210a is stronger, and the first adhesive tape 210 is not easily deformed, thereby reducing the possibility of short circuit between the positive electrode sheet 110 and the negative electrode sheet 130 due to deformation of the first adhesive tape 210, thereby improving the safety of the battery cell; when H1 is less than or equal to 20μm, the base layer 210a can have less influence on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell; therefore, when 4μm≤H1≤20μm, the supporting force of the base layer 210a is stronger, and the first adhesive tape 210 is not easily deformed, thereby reducing the possibility of short circuit between the positive electrode sheet 110 and the negative electrode sheet 130 due to deformation of the first adhesive tape 210, thereby improving the safety of the battery cell, and the base layer 210a can have less influence on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell.

[0077] In some embodiments, the thickness of the first adhesive layer 210 b is H2, which satisfies 2 μm≤H2≤10 μm. For example, H2 may be 2 μm, 6 μm, or 10 μm.

[0078] When H2 is greater than or equal to 2 μm, the first adhesive layer 210b can have a higher adhesive force, the connection strength between the first adhesive tape 210 and the single-sided coating area 112 is higher, and the first adhesive tape 210 is not easy to separate from the single-sided coating area 112, so as to maintain the insulation between the positive electrode plate 110 and the negative electrode plate 130, so that the safety of the battery cell is higher, and the first adhesive tape 210 has a better binding effect on the metal ions in the coating area, reducing the possibility of metal ion precipitation, which is beneficial to prolonging the service life of the battery cell; when H2 is less than or equal to 10 μm, the first adhesive layer 210b can have a smaller effect on the thickness of the battery cell, which is beneficial to improving the energy efficiency of the battery cell. density; therefore, when 2μm≤H2≤10μm, the adhesion of the first adhesive layer 210b can be higher, the connection strength between the first adhesive tape 210 and the single-sided coating area 112 can be higher, and the first adhesive tape 210 is not easy to separate from the single-sided coating area 112 to maintain the insulation of the positive electrode plate 110 and the negative electrode plate 130, so that the safety of the battery cell is higher, and the first adhesive tape 210 has a better binding effect on the metal ions in the coating area, reducing the possibility of metal ion precipitation, which is beneficial to extending the service life of the battery cell, and the first adhesive layer 210b can have less effect on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell.

[0079] In some embodiments, the thickness of the second adhesive layer 210 c is H3, which satisfies 1 μm≤H3≤5 μm. For example, H3 may be 1 μm, 3 μm, or 5 μm.

[0080] When H3 is greater than or equal to 1 μm, the bonding force of the second adhesive layer 210c is high, the connection strength between the first adhesive tape 210 and the double-sided empty foil area 113 is high, and the possibility of displacement of the double-sided empty foil area 113 relative to the single-sided coated area 112 is reduced, thereby reducing the possibility of short circuit between the double-sided empty foil area 113 and the negative electrode sheet 130, which can improve the safety of the battery cell; when H3 is less than or equal to 5 μm, the second adhesive layer 210c has little effect on the thickness of the battery cell, which is beneficial to improving the energy efficiency of the battery cell. quantity density; therefore, when 1μm≤H3≤5μm, the adhesion force of the second adhesive layer 210c can be made higher, the connection strength between the first adhesive tape 210 and the double-sided empty foil area 113 is higher, and the possibility of displacement of the double-sided empty foil area 113 relative to the single-sided coated area 112 is reduced, thereby reducing the possibility of short circuit between the double-sided empty foil area 113 and the negative electrode plate 130, which can improve the safety of the battery cell, and the second adhesive layer 210c can have less effect on the thickness of the battery cell, which is beneficial to improving the energy density of the battery cell.

[0081] In some embodiments, the base layer 210a includes a polyethylene terephthalate material and / or a polyimide material.

[0082] By making the base layer 210a include polyethylene terephthalate material and / or polyimide material, the base layer 210a can have a stronger supporting force and the first adhesive tape 210 is not easily deformed, thereby reducing the possibility of short circuit between the positive electrode plate 110 and the negative electrode plate 130 due to deformation of the first adhesive tape 210, thereby improving the safety of the battery cell.

[0083] In some embodiments, the first adhesive layer 210b includes a polyolefin material and / or a rubber material.

[0084] By making the first adhesive layer 210b include polyolefin material and / or rubber material, the adhesion force of the first adhesive layer 210b can be higher, the connection strength between the first adhesive tape 210 and the single-sided coating area 112 can be higher, and the first adhesive tape 210 is not easy to separate from the single-sided coating area 112, so as to maintain the insulation between the positive electrode plate 110 and the negative electrode plate 130, so that the safety of the battery cell is higher; and the first adhesive layer 210b has strong corrosion resistance, which can reduce the risk of short circuit between the positive electrode plate 110 and the negative electrode plate 130 after the first adhesive layer 210b is corroded by the electrolyte, thereby further improving the safety of the battery cell.

[0085] In some embodiments, the second adhesive layer 210c includes a polyolefin material and / or a rubber material.

[0086] By making the second adhesive layer 210c include polyolefin material and / or rubber material, the adhesive force of the second adhesive layer 210c can be made higher, and the connection strength between the first adhesive tape 210 and the double-sided empty foil area 113 can be made higher, thereby reducing the possibility of displacement of the double-sided empty foil area 113 relative to the single-sided coated area 112, thereby reducing the possibility of short circuit between the double-sided empty foil area 113 and the negative electrode plate 130, thereby improving the safety of the battery cell; and the second adhesive layer 210c has strong corrosion resistance, which can reduce the risk of short circuit between the positive electrode plate 110 and the negative electrode plate 130 after the second adhesive layer 210c is corroded by the electrolyte, thereby further improving the safety of the battery cell.

[0087] In some embodiments, the battery cell includes a second adhesive tape 220 , and the second adhesive tape 220 is used to fix the winding end of the positive electrode sheet 110 .

[0088] By making the battery cell include the second adhesive tape 220, the second adhesive tape 220 is used to fix the winding tail end of the positive electrode plate 110, which can further reduce the possibility of displacement of the double-sided empty foil area 113 of the positive electrode plate 110 relative to the single-sided coated area 112, thereby reducing the possibility of short circuit between the double-sided empty foil area 113 and the negative electrode plate 130, thereby improving the safety of the battery cell.

[0089] In some embodiments, the winding end of the positive electrode sheet 110 can also be achieved by using the first adhesive tape 210 including two adhesive layers, that is, the second adhesive tape 220 can be eliminated, which can further reduce the thickness of the electrode assembly 100 and improve the energy density of the battery cell.

[0090] In some embodiments, the battery cell includes a positive electrode tab 310 and a third tape 230, the positive electrode tab 310 is connected to the positive electrode plate 110, a portion of the third tape 230 is attached to the positive electrode tab 310, and the other portion is attached to the positive electrode plate 110, along the thickness direction Z of the electrode assembly, the projection of the second tape 220 does not overlap with the projection of the third tape 230.

[0091] By making a part of the third tape 230 attached to the positive electrode ear 310 and the other part attached to the positive electrode plate 110, along the thickness direction Z of the electrode assembly, the projection of the second tape 220 and the projection of the third tape 230 do not overlap, so that in the thickness direction Z of the electrode assembly, the thickness of the second tape 220 and the thickness of the third tape 230 will not overlap, which is beneficial to reducing the thickness of the battery cell and improving the energy density of the battery cell.

[0092] In some embodiments, the battery cell includes a negative electrode tab 320 and a fourth tape 240, the negative electrode tab 320 is connected to the negative electrode plate 130, a portion of the fourth tape 240 is attached to the negative electrode tab 320, and the other portion is attached to the negative electrode plate 130, along the thickness direction Z of the electrode assembly, the projection of the second tape 220 does not overlap with the projection of the fourth tape 240.

[0093] By making a part of the fourth tape 240 attached to the negative electrode tab 320 and the other part attached to the negative electrode plate 130, along the thickness direction Z of the electrode assembly, the projection of the second tape 220 and the projection of the fourth tape 240 do not overlap, so that in the thickness direction Z of the electrode assembly, the thickness of the second tape 220 and the thickness of the fourth tape 240 will not overlap, which is beneficial to reducing the thickness of the battery cell and improving the energy density of the battery cell.

[0094] In some embodiments, the positive electrode tab 310 and the positive electrode sheet 110 may be integrally formed, or connected by welding, bonding, etc. The negative electrode tab 320 and the negative electrode sheet 130 may be integrally formed, or connected by welding, bonding, etc.

[0095] In some embodiments, the battery cell further includes a fifth adhesive tape 250 , which is attached to a side of the double-sided empty foil area 113 facing the winding center of the electrode assembly.

[0096] By making the battery cell also include the fifth adhesive tape 250, the fifth adhesive tape 250 is attached to the side of the double-sided empty foil area 113 facing the winding center of the electrode assembly, so that the fifth adhesive tape 250 can play an insulating role between the double-sided empty foil area 113 and the negative electrode plate 130, thereby reducing the possibility of short circuit between the positive electrode plate 110 and the negative electrode plate 130, and improving the safety of the battery cell.

[0097] In some embodiments, a portion of the fifth adhesive tape 250 is attached to the double-sided empty foil area 113 , and another portion is attached to a side of the single-sided coating area 112 where the active material layer is disposed.

[0098] Due to the inevitable errors in the preparation process, if the fifth tape 250 is entirely set in the double-sided empty foil area 113, there may be a gap between the fifth tape 250 and the active material layer of the single-sided coated area 112, resulting in a short circuit between the positive electrode sheet 110 and the negative electrode sheet 130. Therefore, by making a part of the fifth tape 250 attached to the double-sided empty foil area 113 and the other part attached to the side of the single-sided coated area 112 where the active material layer is provided, the fifth tape 250 can cover the end of the double-sided empty foil area 113 close to the single-sided coated area 112, thereby reducing the risk of short circuit between the positive electrode sheet 110 and the negative electrode sheet 130, thereby improving the safety of the battery cell.

[0099] Referring to Table 1, Comparative Example X in Table 1 is a solution in which adhesive tape is provided at the head and tail of the electrode assembly after winding. W1 is the width of the second portion of the first adhesive tape, W2 is the width of the double-sided empty foil area, L1 is the length of the second portion of the first adhesive tape, L2 is the length of the double-sided empty foil area, and W3 is the width of the first portion of the first adhesive tape.

[0100] Comparative Example X is the structure mentioned in the background technology without eliminating the head and tail adhesive tapes.

[0101] The test method for the energy density of the battery cell is:

[0102] (1) Place the battery in an environment of 25℃±2℃.

[0103] (2) Charge the cell to 4.5V at 1C constant current, then charge to 0.05C at constant voltage.

[0104] (3) Discharge the cell to 3.0V at a constant current of 0.2C.

[0105] (4) Repeat steps 2-3 three times and take the last capacity as the cell capacity.

[0106] (5) Battery cell energy density = battery cell capacity * discharge platform / battery cell volume.

[0107] Table 1 Energy density, drop pass rate and package leakage ratio of battery cells

[0108]

[0109] The test method for drop pass rate is:

[0110] (1) Place the battery in an environment of 25℃±2℃.

[0111] (2) Charge the cell to 4.5V at 1C constant current, then charge to 0.05C at constant voltage.

[0112] (3) Drop the battery cell from a height of 1.5 m, with each of the six surfaces facing downward once and each of the four corners facing downward once, onto a marble floor for a total of 10 rounds of testing. The order of the drops is front-back-bottom-top-left-right-upper left corner-upper right corner-lower left corner-lower right corner.

[0113] (4) Judgment criteria: No fire, explosion, smoke, or leakage, and the voltage drop of the battery cell compared to the initial state is less than 100mV.

[0114] The test method for package leakage rate is:

[0115] (1) In an environment of 25℃±2℃, place the electrode assembly between two layers of 100um aluminum-plastic film to form a sandwich structure.

[0116] (2) Place the sandwich structure as a whole in the upper and lower 200±5℃ hot pressing heads, and heat press with a force of 120±10kg for 15±0.1s to complete the packaging of the three sides.

[0117] (3) Inject 10 g of electrolyte from the non-packaged side of the cell that has completed three-side packaging.

[0118] (4) Place the unpackaged side in the upper and lower 200±5℃ hot pressing heads and complete the packaging with a force of 120±10kg for 15±0.1s.

[0119] (5) Place the packaged battery cell in a 60°C environment for 48 hours and visually inspect the sealed area for any electrolyte leakage.

[0120] According to Table 1, the following conclusions can be drawn:

[0121] 1. Referring to Comparative Example X and Examples 1-10, the energy density of the battery cell in the solution without removing the head and tail tapes is lower.

[0122] 2. Referring to Comparative Examples 1-4 and Examples 1-10, W1 is greater than W2, indicating that the width direction of the adhesive tape exceeds the edge of the double-sided empty foil area, L1-L2 is greater than 0, and the length direction of the surface adhesive tape exceeds the trailing edge of the double-sided empty foil area. When the adhesive tape does not exceed the double-sided empty foil area in the length direction or the width direction, the drop pass rate is low.

[0123] 3. Refer to Comparative Examples 3-4, Examples 1 and 3-5. As L1-L2 increases, the drop pass rate of the battery cell will increase, which is beneficial to improving the reliability of the battery cell, but the packaging leakage ratio will increase, affecting the safety of the battery cell. When L1-L2≤0, the drop pass rate of the battery cell is low, affecting the reliability of the battery cell. When L1-L2>10mm, the first adhesive tape may extend into the sealing area of ​​the packaging bag of the battery cell, resulting in a high packaging leakage ratio of the battery cell, affecting the safety of the battery cell. When 0<L1-L2≤10mm, both the drop pass rate of the battery cell can be made higher and the packaging leakage ratio of the battery cell can be made lower.

[0124] 4. See Examples 1, 6-10. As W3 increases, the energy density of the battery cell will decrease, affecting the battery cell's endurance. When W3=0, although the energy density of the battery cell is high, there is a risk of short circuit, and the battery cell's drop pass rate is low. When W3>10mm, the energy density of the battery cell is low, affecting the battery cell's endurance. When 0<W3≤10mm, the battery cell's energy density is high and the battery cell's drop pass rate is high.

[0125] An embodiment of the present application provides an electrical device, comprising a battery cell according to any of the above solutions, and the battery cell is used to provide electrical energy to the electrical device.

[0126] The electrical device may be any of the aforementioned devices or systems that use the battery cells.

[0127] 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.

[0128] 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 variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, characterized in that: The electrode assembly comprises an electrode assembly, wherein the electrode assembly is formed by winding a stacked positive electrode sheet, a separator and a negative electrode sheet, and the outermost electrode sheet of the electrode assembly is the positive electrode sheet; The positive electrode sheet comprises a double-sided coating area, a single-sided coating area and a double-sided empty foil area which are arranged in sequence from the winding starting end to the winding ending end; The battery cell further comprises a first adhesive tape, which is attached to a side of the single-sided coating area where no active material layer is provided, and is at least partially provided on the positive electrode sheet of the second circle from the outside to the inside of the battery cell; Along the winding direction, the double-sided empty foil area has a first edge away from the single-sided coated area, and the first adhesive tape exceeds the first edge; Along the winding axis direction, the double-sided empty foil area has a second edge and a third edge opposite to each other, the first adhesive tape exceeds the second edge and the third edge, and the battery cell capacity is less than 3Ah.

2. The battery cell according to claim 1, characterized in that: The first adhesive tape includes a first part and a second part, the first part is attached to the double-sided coating area, and the second part is attached to the single-sided coating area.

3. The battery cell according to claim 2, characterized in that: Along the winding axis direction, the length of the second portion is L1, and the length of the double-sided empty foil area is L2, satisfying L1>L2; Along the winding direction, the width of the second portion is W1, and the width of the double-sided empty foil area is W2, satisfying W1>W2; Observed along the radial direction of the winding, the second portion completely covers the double-sided empty foil area.

4. The battery cell according to claim 3, characterized in that: 0<L1-L2≤10mm.

5. The battery cell according to claim 2, characterized in that: Along the winding direction, the width of the first portion is W3, satisfying 0<W3≤10mm.

6. The battery cell according to claim 1, characterized in that: A portion of the double-sided empty foil area is located on one side of the electrode assembly along the thickness direction thereof, and another portion of the double-sided empty foil area is located on one side of the electrode assembly along the first direction; The first direction, the winding axis direction, and the thickness direction of the electrode assembly are perpendicular to each other.

7. The battery cell according to claim 1, characterized in that: The first adhesive tape includes a base layer and a first adhesive layer, and the first adhesive layer is arranged on a side of the base layer facing the single-sided coating area.

8. The battery cell according to claim 7, characterized in that: The first adhesive tape includes a second adhesive layer, and the second adhesive layer is arranged on a side of the base layer facing away from the single-sided coating area.

9. The battery cell according to claim 8, characterized in that: The thickness of the base layer is H1, which satisfies 4μm≤H1≤20μm; the thickness of the first adhesive layer is H2, which satisfies 2μm≤H2≤10μm; and the thickness of the second adhesive layer is H3, which satisfies 1μm≤H3≤5μm.

10. The battery cell according to claim 8, characterized in that: The base layer includes polyethylene terephthalate material and / or polyimide material, the first adhesive layer includes polyolefin material and / or rubber material, and the second adhesive layer includes polyolefin material and / or rubber material.

11. The battery cell according to claim 1, characterized in that: The battery cell includes a second adhesive tape, and the second adhesive tape is used to fix the winding end of the positive electrode plate; The battery cell comprises a positive electrode tab and a third adhesive tape, wherein the positive electrode tab is connected to the positive electrode plate, a portion of the third adhesive tape is attached to the positive electrode tab, and another portion of the third adhesive tape is attached to the positive electrode plate, and along the thickness direction of the electrode assembly, a projection of the second adhesive tape does not overlap with a projection of the third adhesive tape; The battery cell includes a negative electrode tab and a fourth tape, the negative electrode tab is connected to the negative electrode plate, a portion of the fourth tape is attached to the negative electrode tab, and another portion is attached to the negative electrode plate, and along the thickness direction of the electrode assembly, the projection of the second tape does not overlap with the projection of the fourth tape.

12. The battery cell according to claim 1, characterized in that: The battery core includes a fifth adhesive tape, and the fifth adhesive tape is attached to a side of the double-sided empty foil area facing the winding center of the electrode assembly.

13. The battery cell according to any one of claims 1 to 12, characterized in that: The first adhesive tape is at least partially disposed on the negative electrode sheet of the second circle from the outside to the inside of the battery cell.

14. An electrical device, characterized in that: The invention comprises a battery cell as described in any one of claims 1 to 13, wherein the battery cell is used to provide electrical energy.

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