A cylindrical lithium-ion battery

Abstract

The present application provides a cylindrical lithium-ion battery, which includes a housing, a negative current collector plate, a wound core, a positive current collector plate and a cap. The housing includes an open inner cavity, and the negative current collector plate, the wound core and the positive current collector plate are disposed in the inner cavity. The cap is disposed on the opening to seal the inner cavity. The wound core is formed by winding and flattening a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence. The length and area parameters of the positive tab area or the negative tab area in the positive electrode sheet and the negative electrode sheet are controlled within a reasonable range to reduce problems such as tab exposure, tab folding, separator scalding and welding explosion points that occur during the flattening and welding process of the wound core.

Description

Technical Field

[0001] This application relates to the technical field of secondary batteries, and more particularly to a cylindrical lithium-ion battery. Background Art

[0002] In related technologies, according to the encapsulation form, lithium-ion batteries can be divided into three forms: square, cylindrical, and soft-pack. Among them, cylindrical lithium-ion batteries have gradually become a research hotspot due to their good consistency, high production efficiency, and strong heat dissipation ability at the system level. Cylindrical batteries are usually encapsulated with a cylindrical steel shell. The bare battery core is made by a winding process to form a cylindrical winding core. During winding, the electrode sheets, separator, and electrode sheets are arranged in sequence and then wound. The two electrode sheets each have a tab area at opposite ends. After winding, tabs are formed at opposite ends along the height direction of the winding core. Then, the tabs at opposite ends are flattened to obtain a flattened layer, and the current collector plate is welded to the flattened layer to lead out the electrodes of the winding core. In the process of welding the current collector plate and the flattened layer of the winding core, problems such as welding burns to the separator, welding explosion points, tab exposure, and tab folding sometimes occur. Summary of the Invention

[0003] Embodiments of this application provide a cylindrical lithium-ion battery to at least solve the technical problems such as welding burns to the separator, welding explosion points, tab exposure, and tab folding in the flattening of the winding core of existing cylindrical lithium-ion batteries.

[0004] An embodiment of the first aspect of this application provides a cylindrical lithium-ion battery, including: a housing, a negative current collector plate, a winding core, a positive current collector plate, and a cap. The housing includes an open inner cavity. The negative current collector plate, the winding core, and the positive current collector plate are disposed in the inner cavity. The cap is disposed on the opening to close the inner cavity;

[0005] The core is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet arranged in sequence and then flattening them. The positive electrode sheet includes a positive current collector, a positive electrode material, and a ceramic material. The positive current collector includes a positive material region and a positive non-material region extending from the positive material region. The positive material region is coated with the positive electrode material. The positive non-material region includes a ceramic region and a bendable positive tab region. The ceramic region is coated with the ceramic material. The positive tab region is not coated with the positive electrode material and the ceramic material. The positive tab region is used to form a positive flattened layer after flattening. The ceramic region is located between the positive material region and the positive tab region. Along the width direction of the positive electrode sheet, the width of the positive electrode sheet is L1, the width of the positive tab region is L2, and the width of the ceramic region is L3. 3% ≤ L2 / L1 ≤ 13%, 1% ≤ L3 / L1 ≤ 10%. The area of the positive material region is S1, and the area of the positive non-material region is S2. 1% ≤ S2 / (S1 + S2) ≤ 15%. The negative electrode sheet includes a negative current collector and a negative electrode material. The negative current collector includes a negative material region and a bendable negative tab region extending from the negative material region. The negative material region is coated with the negative electrode material. The negative tab region is not coated with the negative electrode material. The negative tab region is used to form a negative flattened layer after flattening. Along the width direction of the negative electrode sheet, the width of the negative electrode sheet is L4, and the width of the negative tab region is L5. 2% ≤ L5 / L4 ≤ 15%. The area of the negative material region is S3, and the area of the negative tab region is S4. 1% ≤ S4 / (S3 + S4) ≤ 15%. The core includes a positive end and a negative end that are opposite to each other in the height direction of the cylindrical lithium-ion battery. The positive tab region is located at the positive end, and the negative tab region is located at the negative end. The cap is connected to the positive end of the core through the positive current collector disk, and the housing is connected to the negative end of the core through the negative current collector disk.

[0006] The cylindrical lithium-ion battery according to the embodiment of the present application has at least the following beneficial effects:

[0007] In the cylindrical lithium-ion battery according to the embodiment of the present application, by defining the relevant parameters between the material region and the non-material region in the electrode sheet, the thickness of the flattened layer in the core is controlled, thereby reducing problems such as separator scalding, welding explosion points, tab exposure, and tab folding.

[0008] In a possible implementation manner, along the direction from the negative end to the positive end, the length by which the separator extends beyond the positive material region is L6, and the length by which the negative material region extends beyond the positive material region is L7. (L2 + L3) > L6, (L2 + L3) > L7.

[0009] In a possible implementation, along the direction from the positive extreme to the negative extreme, the length by which the separator extends beyond the negative electrode material region is L8, and L5 > L8.

[0010] In a possible implementation, along the direction from the negative extreme to the positive extreme, the length by which the positive electrode tab region extends beyond the separator is L9, where 1 mm ≤ L9 ≤ 6 mm. Along the direction from the positive extreme to the negative extreme, the length by which the negative electrode tab region extends beyond the separator is L10, where 1 mm ≤ L10 ≤ 6 mm. By controlling the lengths of L9 and L10, it helps to balance the safety of the battery and the manufacturing material cost.

[0011] In a possible implementation, 3.5 mm ≤ L9 ≤ 4.5 mm, 3.5 mm ≤ L10 ≤ 4.5 mm. The height of the positive electrode flattening layer is H1, and the height of the positive electrode flattening layer is the length from the outermost extension of the positive extreme along the width direction of the positive electrode sheet to the ceramic region. The height of the negative electrode flattening layer is H2, and the height of the negative electrode flattening layer is the length from the outermost extension of the negative extreme along the width direction of the negative electrode sheet to the negative electrode material region, H1 = 472.2 - 293×L9 + 92.96×L9 2 +M1, H2 = 472.2 - 293×L10 + 92.96×L10 2 +M1, -0.15 mm ≤ M1 ≤ 0.15 mm. This helps to guide those skilled in the art when engaged in R & D work to quickly obtain the parameters of L9 and L10 in the electrode sheet according to the requirements of the thickness of the flattening layer, thereby improving the R & D efficiency.

[0012] In a possible implementation, the thickness of the positive electrode current collector is D1, and the thickness of the negative electrode current collector is D2, where 0.004 mm ≤ D1 ≤ 0.013 mm, 0.004 mm ≤ D2 ≤ 0.013 mm. The height of the positive electrode flattening layer is H1, and the height of the positive electrode flattening layer is the length from the outermost extension of the positive extreme along the width direction of the positive electrode sheet to the ceramic region. The height of the negative electrode flattening layer is H2, and the height of the negative electrode flattening layer is the length from the outermost extension of the negative extreme along the width direction of the positive electrode sheet to the negative electrode material region, -0.15 mm ≤ M2 ≤ 0.15 mm. This helps to guide those skilled in the art when engaged in R & D work to quickly obtain the thickness parameters of the positive electrode current collector or the negative electrode current collector according to the requirements of the thickness of the flattening layer, thereby improving the R & D efficiency.

[0013] In a possible implementation, the positive tab area extends along the length direction of the positive electrode sheet, and the negative tab area extends along the length direction of the negative electrode sheet. Designing both in the full-tab manner helps to achieve a flattened layer with low internal resistance after flattening, improve the overcurrent capacity of the current, reduce heat generation, increase the battery energy utilization efficiency, and enhance the safety of battery use.

[0014] In a possible implementation, the winding core includes a starting end for starting winding and an end opposite to the starting end. At the starting end, along the length direction of the positive electrode sheet, the length by which the positive electrode material area exceeds the positive tab area is N1, and the length by which the negative electrode material area exceeds the negative tab area is N2, where 60 mm ≤ N1 ≤ 140 mm and 40 mm ≤ N2 ≤ 100 mm; at the end, along the length direction of the positive electrode sheet, the length by which the positive electrode material area exceeds the positive tab area is N3, and the length by which the negative electrode material area exceeds the negative tab area is N4, where 40 mm ≤ N3 ≤ 100 mm and 30 mm ≤ N4 ≤ 90 mm. By designing the cutting length, it helps to balance the overcurrent capacity of the battery and reduce tab flanging.

[0015] In a possible implementation, the height of the winding core is H3, and the height of the cylindrical lithium-ion battery is H4, where 90% ≤ H3 / H4 ≤ 98% and 65 mm ≤ H3 ≤ 160 mm. Setting the range of H3 / H4 at 90% - 98% helps to balance the welding effect between the flattened layer and the current collector plate and the unit volume energy density of the cylindrical lithium-ion battery.

[0016] In a possible implementation, the thickness of the positive current collector plate is D3, and the thickness of the negative current collector plate is D4, where 0.1 mm ≤ D3 ≤ 1 mm and 0.1 mm ≤ D4 ≤ 1 mm. The height of the positive flattened layer is H1, and the height of the positive flattened layer is the length from the outermost extension of the positive end to the ceramic area along the width direction of the positive electrode sheet. The height of the negative flattened layer is H2, and the height of the negative flattened layer is the length from the outermost extension of the negative end to the negative electrode material area along the width direction of the positive electrode sheet. H1 = -0.1175 + 3.55×D3 - 5×D2 2 + M3, H2 = -0.1175 + 3.55×D4 - 5×D2 2 + M3, where -0.15 mm ≤ M3 ≤ 0.15 mm. This helps to guide those skilled in the art to quickly obtain the thickness parameters of the positive current collector plate or the negative current collector plate according to the requirements of the thickness of the flattened layer during the R & D work, thereby improving the R & D efficiency.

[0017] In a possible implementation manner, along the radial direction of the core, an included angle θ is formed between the hypotenuse of the outermost positive electrode tab area where the positive electrode flattening layer is formed and the radius of the core, and 20° ≤ θ ≤ 90°. Description of the Drawings

[0018] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 is a schematic cross-sectional view of a cylindrical lithium-ion battery provided by an embodiment of the present application;

[0020] Figure 2 is a schematic structural view of a core of a cylindrical lithium-ion battery provided by an embodiment of the present application;

[0021] Figure 3 is a side view of a core of a cylindrical lithium-ion battery when stacked before winding provided by an embodiment of the present application;

[0022] Figure 4 is a schematic view of a positive electrode tab of a cylindrical lithium-ion battery before winding provided by an embodiment of the present application;

[0023] Figure 5 is a schematic view of a negative electrode tab of a cylindrical lithium-ion battery before winding provided by an embodiment of the present application;

[0024] Figure 6 is Figure 5 a partial schematic view at A in;

[0025] Figure 7 is a schematic cross-sectional view of a core of a cylindrical lithium-ion battery provided by an embodiment of the present application;

[0026] Figure 8 is a schematic cross-sectional view of a positive electrode current collector of a cylindrical lithium-ion battery provided by an embodiment of the present application;

[0027] Figure 9 is a schematic cross-sectional view of a negative electrode current collector of a cylindrical lithium-ion battery provided by an embodiment of the present application.

[0028] Reference Signs:

[0029] 100 - Outer Shell;

[0030] 200 - Negative Electrode Current Collector;

[0031] 300 - Core, 310 - Positive electrode sheet, 311 - Positive current collector, 3111 - Positive material area, 3112 - Positive non - material area, 3112a - Ceramic area, 3112b - Positive tab area, 3113 - Positive flattened layer, 3114 - Starting end, 3115 - Ending end, 312 - Positive electrode material, 313 - Ceramic material, 320 - Separator, 330 - Negative electrode sheet, 331 - Negative current collector, 3311 - Negative material area, 3312 - Negative tab area, 3313 - Negative flattened layer, 332 - Negative electrode material, 340 - Positive terminal, 350 - Negative terminal, 360 - Central hole;

[0032] 400 - Positive current - collecting disk;

[0033] 500 - Cap. Detailed implementation mode

[0034] The embodiments of the present implementation mode are described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present implementation mode and should not be construed as a limitation to the present implementation mode.

[0035] In the description of the present implementation mode, it should be understood that for the orientation description, such as the upper, lower, front, rear, left, right, etc., the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings. It is only for the convenience of describing the present implementation mode and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present implementation mode.

[0036] In the description of the present implementation mode, the meaning of "several" is one or more, the meaning of "multiple" is two or more, "greater than", "less than", "exceeding", etc. are understood as not including the present number, and "above", "below", "within", etc. are understood as including the present number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0037] In the description of the present implementation mode, unless otherwise clearly defined, words such as "set", "installed", "connected", etc. should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meanings of the above words in the present implementation mode in combination with the specific content of the technical solution.

[0038] In the related art, a cylindrical lithium-ion battery includes a housing, a negative current collector plate, a wound core, a positive current collector plate, and a cap. The housing includes an open inner cavity, and the negative current collector plate, the wound core, and the positive current collector plate are disposed in the inner cavity. The cap is disposed on the opening to close the inner cavity. The production of the wound core includes winding and flattening processes. The production materials of the wound core include a positive electrode sheet, a separator, and a negative electrode sheet. Both the positive electrode sheet and the negative electrode sheet are generally rectangular. Along the width direction of the electrode sheet, there are a material area and a non-material area extending from the material area. Both the material area and the non-material area extend along the length direction of the electrode sheet. The material area is coated with electrode material, the positive electrode sheet is coated with positive electrode material, and the negative electrode sheet is coated with negative electrode material. The non-material area is not coated with electrode material. The positive electrode sheet, the separator, and the negative electrode sheet are arranged in sequence, and the long sides of the positive electrode sheet and the negative electrode sheet are arranged correspondingly. Among them, the non-material area of the positive electrode sheet is arranged opposite to the non-material area of the negative electrode sheet, that is, along the width direction of the electrode sheet, the non-material area of the positive electrode sheet is located at one end, and the non-material area of the negative electrode sheet is located at the other end. The non-material areas of the two electrode sheets are arranged oppositely. After the arrangement is completed, one wide side of the electrode sheet is used as the starting end, and the arranged two electrode sheets and the separator are wound along the length direction of the electrode sheet to form a cylinder. The opposite ends of the cylinder along its height direction respectively correspond to the non-material area of the positive electrode sheet and the non-material area of the negative electrode sheet. The non-material area can also be called a tab. After the winding is completed, a flattening process is carried out. The non-material areas at both ends of the cylinder are flattened to form a flattened layer. After the current collector plate is welded to the flattened layer, the positive and negative electrodes of the wound core are led out. The current collector plate and the flattened layer play a role in current overcurrent during the subsequent use of the battery. Therefore, the welding effect between the current collector plate and the flattened layer will affect the subsequent use effect of the battery.

[0039] During the flattening process of the production of the wound core, sometimes the tabs are exposed or the tabs are folded. The tabs extend along the height direction of the wound core before flattening. During flattening, the tabs are flattened towards the axis direction of the wound core. Under normal circumstances, the tabs do not exceed the outer edge of the cylinder in the radial direction of the wound core. If they exceed the outer edge, it is called tab exposure at this time. Since the size specifications of cylindrical lithium-ion batteries have been relatively established in the industry, the diameter of the battery housing is fixed. At the same time, in order to improve the energy density of the battery, the diameter of the wound core is increased as much as possible. Therefore, once the tabs are exposed outside the outer edge of the wound core or the tabs are folded, the wound core after winding and flattening cannot be normally inserted into the battery housing due to the obstruction of the exposed tabs. During the welding process of the current collector plate to the flattened layer, sometimes problems such as separator scalding and welding explosion points occur.

[0040] Since the above problems involve the flattening process, the welding process, and the core itself, after careful research, the applicant found that the design of the core itself has a great direct relationship with causing the above problems. Among them, through experimental research, it is found that the thickness of the flattening layer has a direct relationship with the occurrence of the above problems. When the thickness of the flattening layer is too thick, during the flattening process, the internal extrusion deformation of the tab is serious, and the tab is easily extruded along the radial direction of the core under the action of the flattening force, resulting in the exposure or folding of the tab. When the flattening layer is too thin, during the welding process, the current collector plate is welded to the outer surface of the flattening layer, and the welding heat is transferred from the outer surface in the direction away from the outer surface. At this time, the flattening layer is very thin, and the heat is quickly transferred to the material area adjacent to the flattening layer, where the material area contains the thin film. At this time, the heat will scald the thin film, resulting in battery scrapping. If the welding time is reduced, there may be a problem that the current collector plate and the flattening layer are not welded sufficiently. There is also a problem of welding explosion points when the flattening layer is too thin. Welding explosion points refer to the situation where some parts are not welded in place. When the tabs are wound, the tabs corresponding to the starting end are pressed by the subsequent tabs, showing a stepped shape. The stacked area of multiple tabs is thicker. If the number of stacked layers is not enough, during welding, the thinner area sometimes has a phenomenon of welding through, that is, explosion points. After welding through, the contact between the current collector plate and the flattening layer is not sufficient, resulting in a poor overcurrent effect of the current and a significant temperature rise at the connection between the current collector plate and the flattening layer.

[0041] In view of the above situation, this application aims to control the thickness of the flattening layer after flattening in order to reduce the probability of the above problems occurring. During the research process, the applicant found that controlling the length of the non-material area (tab area) to be flattened in the width direction of the electrode sheet can effectively control the thickness of the flattening layer.

[0042] This application provides a cylindrical lithium-ion battery. Please refer to Figures 1 to 9, comprising a housing 100, a negative current collector plate 200, a wound core 300, a positive current collector plate 400 and a cap 500. The housing 100 includes an open inner cavity. The negative current collector plate 200, the wound core 300 and the positive current collector plate 400 are disposed in the inner cavity, and the cap 500 is covered on the opening to close the inner cavity. The wound core 300 is formed by winding and then flattening a positive electrode sheet 310, a separator 320 and a negative electrode sheet 330 arranged in sequence. The positive electrode sheet 310 includes a positive current collector 311, a positive electrode material 312 and a ceramic material 313. The positive current collector 311 includes a positive material region 3111 and a positive non-material region 3112 extending from the positive material region 3111. The positive material region 3111 is coated with the positive electrode material 312. The positive non-material region 3112 includes a ceramic region 3112a and a bendable positive tab region 3112b. The ceramic region 3112a is coated with the ceramic material 313. The positive tab region 3112b is not coated with the positive electrode material 312 and the ceramic material 313. The positive tab region 3112b is used to form a positive flattened layer 3113 after flattening. The ceramic region 3112a is located between the positive material region 3111 and the positive tab region 3112b. Along the width direction of the positive electrode sheet 310, the width of the positive electrode sheet 310 is L1, the width of the positive tab region 3112b is L2, and the width of the ceramic region 3112a is L3, 3% ≤ L2 / L1 ≤ 13%, 1% ≤ L3 / L1 ≤ 10%. What L2 / L1 affects is the length L2 of the positive tab region 3112b. If L2 / L1 is too small, the positive tab region 3112b is too short, and the thickness of the positive flattened layer 3113 after flattening is too thin, which is not conducive to welding the positive flattened layer 3113 to the positive current collector plate 400. If L2 / L1 is too large, the positive tab region 3112b is too long, and the thickness of the positive flattened layer 3113 after flattening is too thick, which will cause material waste when the overcurrent can be satisfied, and the too thick positive flattened layer 3113 will slow down the electrolyte injection and infiltration speed. It can be understood that due to the flattening process of the wound core 300, the widths such as L1 and L2 refer to the width after unfolding the flattened layer of the wound core 300, or the length of the electrode sheet before winding. The same applies to the subsequent parameters related to length.

[0043] As an embodiment, the area of the positive material region 3111 is S1, and the area of the positive non-material region 3112 is S2, 1% ≤ S2 / (S1 + S2) ≤ 15%. If S2 / (S1 + S2) is too small, it means that the positive non-material region 3112 is too small, which is not conducive to the manufacturing process and the tab flattening and forming. If S2 / (S1 + S2) is too large, it means that the positive non-material region 3112 is too large, wasting materials and increasing the risk of roller breakage.

[0044] As an implementation manner, the negative electrode sheet 330 includes a negative current collector 331 and a negative electrode material 332. The negative current collector 331 includes a negative electrode material region 3311 and a bendable negative electrode tab region 3312 extending from the negative electrode material region 3311. The negative electrode material region 3311 is coated with the negative electrode material 332, and the negative electrode tab region 3312 is not coated with the negative electrode material 332. The negative electrode tab region 3312 is used to form a flattened negative electrode layer 3313 after being flattened. Along the width direction of the negative electrode sheet 330, the width of the negative electrode sheet 330 is L4, and the width of the negative electrode tab region 3312 is L5, where 2% ≤ L5 / L4 ≤ 15%. L5 / L4 affects the width L4 of the negative electrode tab region 3312 (the part for flattening) of the negative electrode sheet 330. If L5 / L4 is too small, the negative electrode tab region 3312 is too short, and the thickness of the flattened negative electrode layer 3313 after flattening is too thin, which is not conducive to welding the flattened negative electrode layer 3313 to the negative current collector plate 200. If L5 / L4 is too large, the negative electrode tab region 3312 is too long, and the thickness of the flattened negative electrode layer 3313 after flattening is too thick, which will cause material waste when the overcurrent can be satisfied, and the too thick flattened negative electrode layer 3313 will slow down the electrolyte infiltration speed. As an implementation manner, the lengths of the positive electrode sheet 310 and the negative electrode sheet 330 are 1300 mm to 1600 mm.

[0045] As an implementation manner, the area of the negative electrode material region 3311 is S3, and the area of the negative electrode tab region 3312 is S4, where 1% ≤ S4 / (S3 + S4) ≤ 15%. If S4 / (S3 + S4) is too small, it means that the negative electrode tab region 3312 is too small, which is not conducive to the manufacturing process and the forming of the flattened tab. If S4 / (S3 + S4) is too large, it means that the negative electrode tab region 3312 is too large, wasting materials and increasing the risk of rolling belt breakage.

[0046] As an implementation manner, the winding core 300 includes a positive extreme end 340 and a negative extreme end 350 that are opposite to each other along the height direction of the cylindrical lithium-ion battery. The positive electrode tab region 3112b is located at the positive extreme end 340, and the negative electrode tab region 3312 is located at the negative extreme end 350. The cap 500 is connected to the positive extreme end 340 of the winding core 300 through the positive current collector plate 400, and the housing 100 is connected to the negative extreme end 350 of the winding core 300 through the negative current collector plate 200.

[0047] As an implementation manner, the positive electrode end 340 of the core 300 is electrically connected to the cap 500 through the positive electrode current collector plate 400. The cap 500 leads out the positive electrode of the core 300, and the cap 500 is the positive electrode of the battery. The outer shell 100 of the battery is a steel outer shell 100. The negative electrode end 350 of the core 300 is electrically connected to the outer shell 100 through the negative electrode current collector plate 200, that is, the steel outer shell 100 serves as the negative electrode of the battery. It can be understood that the outer shell 100 can also be made of other conductive materials that do not react with the battery electrolyte.

[0048] As an implementation manner, the positive electrode material area 3111, the ceramic area 3112a, and the positive electrode tab area 3112b of the positive electrode current collector 311 all extend along the length direction of the positive electrode plate 310. As an implementation manner, the ceramic area is coated with a ceramic material 313, and the ceramic material 313 is composed of one or more inorganic material particles such as silicon dioxide, titanium dioxide, zirconium dioxide, zinc oxide, iron sesquioxide, aluminum sesquioxide, manganese dioxide, magnesium oxide, boehmite, gypsum, talc, and calcite. Using the above inorganic material particles to make the ceramic material 313 has good thermal stability and can still play an electrical insulation role in a high-temperature environment; at the same time, it can provide mechanical support for the positive electrode active material coating and enhance the structural stability.

[0049] As an implementation manner, along the direction from the negative electrode end 350 to the positive electrode end 340, the length by which the separator 320 extends beyond the positive electrode material area 3111 is L6, and the length by which the negative electrode material area 3311 extends beyond the positive electrode material area 3111 is L7. (L2 + L3) > L6, (L2 + L3) > L7, so that the separator 320 insulates the positive electrode current collector 311 from the negative electrode current collector 331, and at the same time can prevent the burrs of the positive electrode current collector 311 and the negative electrode current collector 331 from piercing the separator 320.

[0050] As an implementation manner, along the direction from the positive electrode end 340 to the negative electrode end 350, the length by which the separator 320 extends beyond the negative electrode material area 3311 is L8, and L5 > L8. When the tab areas (including the positive electrode tab area 3112b and the negative electrode tab area 3312) are flattened into a flattened layer, the separator 320 is prevented from being kneaded into the flattened layer to avoid damaging the separator 320.

[0051] As an implementation manner, in the direction from the negative electrode end 350 to the positive electrode end 340, the length by which the positive electrode tab region 3112b extends beyond the separator 320 is L9, where 1 mm ≤ L9 ≤ 6 mm. In the direction from the positive electrode end 340 to the negative electrode end 350, the length by which the negative electrode tab region 3312 extends beyond the separator 320 is L10, where 1 mm ≤ L10 ≤ 6 mm. If L9 and L10 are too short, it is difficult to achieve the flattening during the flattening process, and the thickness of the flattened layer (including the positive electrode flattened layer 3113 and the negative electrode flattened layer 3313) is relatively thin, there is a risk of welding through and scalding the separator 320 when welding to the current collector plate, and there is almost no process window. At the same time, the positive electrode tab region 3112b or the negative electrode tab region 3312 after flattening is not in a straightened state, which will cause displacement during the use of the battery, have a shunting effect on the current, increase the heat generation, and generate an electrostatic effect, thus affecting the stability and safety of the battery charge and discharge cycle. If L9 and L10 are too long, it will cause the flattened layer to be too thick, increase the material cost of the electrode sheet, and reduce the effect of electrolyte injection and infiltration. By controlling the lengths of L9 and L10, it helps to balance the safety of the battery and the manufacturing material cost.

[0052] As an implementation manner, L9 and L10 are further preferably 3.5 mm ≤ L9 ≤ 4.5 mm, 3.5 mm ≤ L10 ≤ 4.5 mm.

[0053] As an implementation manner, the height of the positive electrode flattened layer 3113 is H1, and the height of the positive electrode flattened layer 3113 is the length from the outermost extension of the positive electrode end 340 to the ceramic region 3112a in the width direction of the positive electrode sheet 310. The height of the negative electrode flattened layer 3313 is H2, and the height of the negative electrode flattened layer 3313 is the length from the outermost extension of the negative electrode end 350 to the negative electrode material region 3311 in the width direction of the negative electrode sheet 330. H1 = 472.2 - 293×L9 + 92.96×L9 2 + M1, H2 = 472.2 - 293×L10 + 92.96×L10 2 + M1, -0.15 mm ≤ M1 ≤ 0.15 mm. It has been previously described that controlling the thickness of the flattened layer is important for the flattening process and the welding process, and the thickness of the flattened layer is controlled by changing the parameters of the electrode sheet. This implementation manner proposes a mathematical relationship between the thickness of the flattened layer and the relevant parameters of the electrode sheet, which can guide those skilled in the art to quickly obtain the parameters of L9 and L10 in the electrode sheet according to the required thickness of the flattened layer when engaged in R & D work, thereby improving the R & D efficiency. In the formula, the length units of H1, H2, L9, and L10 are all mm.

[0054] As an implementation manner, the thickness of the positive current collector 311 is D1, and the thickness of the negative current collector 331 is D2, where 0.004 mm ≤ D1 ≤ 0.013 mm and 0.004 mm ≤ D2 ≤ 0.013 mm. The height of the positive flattening layer 3113 is H1, and the height of the positive flattening layer 3113 is the length from the outermost extension of the positive electrode end 340 to the ceramic region 3112a along the width direction of the positive electrode sheet 310. The height of the negative flattening layer 3313 is H2, and the height of the negative flattening layer 3313 is the length from the outermost extension of the negative electrode end 350 to the negative electrode material region 3311 along the width direction of the positive electrode sheet 310. -0.15 mm ≤ M2 ≤ 0.15 mm. In the formula, the length units of H1, H2, D1, and D2 are all mm. This implementation manner presents a mathematical relationship between the thicknesses of the positive current collector 311 and the negative current collector 331 and the thickness of the flattening layer, which can guide those skilled in the art to quickly obtain the thickness parameters of the positive current collector 311 or the negative current collector 331 according to the requirements of the thickness of the flattening layer during the R & D work, thereby improving the R & D efficiency.

[0055] As an implementation manner, the positive tab region 3112b extends along the length direction of the positive electrode sheet 310, and the negative tab region 3312 extends along the length direction of the negative electrode sheet 330. Both the positive tab region 3112b and the negative tab region 3312 are tabs. Designing both of them in the form of full tabs helps to achieve a flattening layer with low internal resistance after flattening, improve the overcurrent capacity of the current, reduce heat generation, improve the battery energy utilization efficiency, and enhance the safety of battery use.

[0056] As an implementation manner, the core 300 includes a starting end 3114 for starting winding and an end 3115 opposite to the starting end 3114. At the starting end 3114, along the length direction of the positive electrode sheet 310, the length by which the positive electrode material region 3111 extends beyond the positive electrode tab region 3112b is N1, and the length by which the negative electrode material region 3311 extends beyond the negative electrode tab region 3312 is N2, where 60 mm ≤ N1 ≤ 140 mm and 40 mm ≤ N2 ≤ 100 mm; at the end 3115, along the length direction of the positive electrode sheet 310, the length by which the positive electrode material region 3111 extends beyond the positive electrode tab region 3112b is N3, and the length by which the negative electrode material region 3311 extends beyond the negative electrode tab region 3312 is N4, where 40 mm ≤ N3 ≤ 100 mm and 30 mm ≤ N4 ≤ 90 mm. After the positive electrode sheet 310 and the negative electrode sheet 330 are coated with electrode materials, their shapes are generally rectangular, and a part of the positive electrode tab region 3112b of the positive electrode sheet 310 and the negative electrode tab region 3312 of the negative electrode sheet 330 are cut. After cutting, winding is started, and the winding is carried out with the wide side (compared with the long side) of the electrode sheet as the axis, and this wide side is the starting end 3114. After winding into the core 300, a central hole 360 along the axial direction of the core 300 is formed in the central part of the core 300. The starting end 3114 is located at the central hole 360 of the core 300, and the end 3115 is located on the outer surface of the core 300. The purpose of cutting is to control the stacking number of the flattened layers and the appearance defects of the flattened layers, and at the same time control the internal resistance. When cutting, if the cutting length of the end 3115 is too long, the thickness of the outer circle of the flattened layer will be too low, the internal resistance of the battery will increase, and the battery performance will be affected; if the cutting length of the end 3115 is too short, the thickness of the outer circle of the flattened layer will be too high, resulting in the outer turning or folding of the electrode tabs. If the cutting length of the starting end 3114 is too long, the thickness of the inner circle of the flattened layer will be too low, the internal resistance of the battery will increase, and the battery performance will be affected; if the cutting length of the starting end 3114 is too small, the central hole 360 will be blocked, the thickness of the inner circle of the flattened layer will be large, and problems such as slow injection efficiency will occur. By designing the cutting length, it helps to balance the overcurrent capacity of the battery and reduce the flanging.

[0057] As an implementation manner, the short sides of the remaining positive electrode tab region 3112b and the negative electrode tab region 3312 after cutting form an acute angle α with the length direction of the electrode sheet, so that the electrode sheet is not easily wrinkled during winding, and the flattened layer after flattening is more uniform.

[0058] As an implementation manner, the height of the core 300 is H3, the height of the cylindrical lithium-ion battery is H4, 90% ≤ H3 / H4 ≤ 98%, and 65 mm ≤ H3 ≤ 160 mm. To ensure the capacity of the cylindrical lithium-ion battery, the height of the material area of the electrode sheet is generally determined. If the thickness of the flattening layer is increased, the total height of the winding will increase, so that the total height of the cylindrical lithium-ion battery will increase after the core 300 is installed in the outer shell 100 of the cylindrical lithium-ion battery. After assembling the cylindrical lithium-ion batteries into a battery pack, the energy density per unit volume of the battery pack will be reduced. Designing H3 / H4 to be 90% - 98% helps to balance the welding effect between the flattening layer and the current collector plate and the energy density per unit volume of the cylindrical lithium-ion battery.

[0059] As an implementation manner, the thickness of the positive current collector plate 400 is D3, the thickness of the negative current collector plate 200 is D4, 0.1 mm ≤ D3 ≤ 1 mm, 0.1 mm ≤ D4 ≤ 1 mm. The height of the positive flattening layer 3113 is H1, and the height of the positive flattening layer 3113 is the length from the outermost extension of the positive electrode end 340 to the ceramic area 3112a along the width direction of the positive electrode sheet 310. The height of the negative flattening layer 3313 is H2, and the height of the negative flattening layer 3313 is the length from the outermost extension of the negative electrode end 350 to the negative electrode material area 3311 along the width direction of the positive electrode sheet 310. H1 = -0.1175 + 3.55×D3 - 5×D3 2 + M3, H2 = -0.1175 + 3.55×D4 - 5×D4 2 + M3, -0.15 mm ≤ M3 ≤ 0.15 mm. If the thickness of the current collector plate is too small, first, the manufacturing difficulty of the current collector plate itself is too high, and second, it is easy to deform during the welding process between the current collector plate and the flattening layer, and it is not firmly combined with the core 300 after welding. If the thickness of the current collector plate is too large, the internal space is reduced and the manufacturing cost is increased. Specifically, the thickness of the current collector plate refers to the thickness of the part in contact with the core 300 during welding. This implementation manner proposes a mathematical relationship between the thicknesses of the positive current collector plate 400 and the negative current collector plate 200 and the thickness of the flattening layer, which can guide those skilled in the art to quickly obtain the thickness parameters of the positive current collector plate 400 or the negative current collector plate 200 according to the requirements of the thickness of the flattening layer during the R & D work, thereby improving the R & D efficiency.

[0060] As an implementation manner, in the positive flattening layer 3113, along the radial direction of the core 300, an included angle θ is formed between the hypotenuse of the positive tab area 3112b located at the outermost extension of the positive flattening layer 3113 and the radius of the core 300, 20° ≤ θ ≤ 90°, to ensure that the positive flattening layer 3113 has sufficient thickness to improve the current-carrying capacity of the positive flattening layer. Similarly, the included angle θ is also provided in the negative flattening layer 3313.

[0061] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this implementation. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0062] Although the embodiments of this implementation have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of this implementation, and the scope of this implementation is defined by the claims and their equivalents.

Claims

1. A cylindrical lithium-ion battery, characterized in that: include: A shell, a negative electrode current collecting disc, a winding core, a positive electrode current collecting disc and a cap, wherein the shell comprises an open inner cavity, the negative electrode current collecting disc, the winding core and the positive electrode current collecting disc are arranged in the inner cavity, and the cap is arranged on the opening to close the inner cavity; The winding core is formed by winding and flattening a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence, the positive electrode sheet comprises a positive current collector, a positive electrode material and a ceramic material, the positive current collector comprises a positive electrode material area and a positive electrode non-material area extending from the positive electrode material area, the positive electrode material area is coated with the positive electrode material, the positive electrode non-material area comprises a ceramic area and a bendable positive electrode tab area, the ceramic area is coated with the ceramic material, and the positive electrode tab area is not coated with the positive electrode material and the ceramic material, The positive electrode tab area is used to form a positive electrode flattened layer after flattening. The ceramic area is located between the positive electrode material area and the positive electrode tab area. Along the width direction of the positive electrode sheet, the width of the positive electrode sheet is L1, the width of the positive electrode tab area is L2, and the width of the ceramic area is L3. 3%≤L2 / L1≤13%, 1%≤L3 / L1≤10%. The area of ​​the positive electrode material area is S1, and the area of ​​the positive electrode non-material area is S2. 1%≤S2 / (S1+S 2)≤15%, the negative electrode sheet comprises a negative electrode current collector and a negative electrode material, the negative electrode current collector comprises a negative electrode material region and a bendable negative electrode tab region extending from the negative electrode material region, the negative electrode material region is coated with the negative electrode material, the negative electrode tab region is not coated with the negative electrode material, the negative electrode tab region is used to form a negative electrode flattening layer after flattening, along the width direction of the negative electrode sheet, the width of the negative electrode sheet is L4, the width of the negative electrode tab region is L5, 2%≤L5 / L 4≤15%, the area of ​​the negative electrode material area is S3, the area of ​​the negative electrode tab area is S4, 1%≤S4 / (S3+S4)≤15%, the winding core comprises a positive terminal and a negative terminal relative to each other in the height direction of the cylindrical lithium-ion battery, the positive electrode tab area is located at the positive terminal, the negative electrode tab area is located at the negative terminal, the cap is connected to the positive terminal of the winding core through the positive current collecting disk, and the outer shell is connected to the negative terminal of the winding core through the negative current collecting disk.

2. The cylindrical lithium-ion battery according to claim 1, characterized in that: Along the direction from the negative terminal to the positive terminal, the length of the diaphragm exceeding the positive electrode material area is L6, and the length of the negative electrode material area exceeding the positive electrode material area is L7, (L2+L3)>L6, (L2+L3)>L7.

3. The cylindrical lithium-ion battery according to claim 1, characterized in that: Along the direction from the positive terminal to the negative terminal, the length of the separator beyond the negative electrode material region is L8, and L5>L8.

4. The cylindrical lithium-ion battery according to claim 1, characterized in that: Along the direction from the negative terminal to the positive terminal, the width of the positive electrode tab area beyond the diaphragm is L9, 1mm≤L9≤6mm, and along the direction from the positive terminal to the negative terminal, the width of the negative electrode tab area beyond the diaphragm is L10, 1mm≤L10≤6mm.

5. The cylindrical lithium-ion battery according to claim 4, characterized in that: 3.5mm≤L9≤4.5mm, 3.5mm≤L10≤4.5mm, the height of the positive electrode flattening layer is H1, the height of the positive electrode flattening layer is the length from the outermost extension of the positive terminal to the ceramic area along the width direction of the positive electrode sheet, the height of the negative electrode flattening layer is H2, the height of the negative electrode flattening layer is the length from the outermost extension of the negative terminal to the negative electrode material area along the width direction of the negative electrode sheet, H1=472.2-293×L9+92.96×L9 2 +M1, H2=472.2-293×L10+92.96×l10 2 +M1,-0.15mm≤M1≤0.15mm.

6. The cylindrical lithium-ion battery according to claim 1, characterized in that: The thickness of the positive electrode current collector is D1, the thickness of the negative electrode current collector is D2, 0.004mm≤D1≤0.013mm, 0.004mm≤D2≤0.013mm, the height of the positive electrode flattening layer is H1, the height of the positive electrode flattening layer is the length from the outermost extension of the positive terminal to the ceramic area along the width direction of the positive electrode sheet, the height of the negative electrode flattening layer is H2, the height of the negative electrode flattening layer is the length from the outermost extension of the negative terminal to the negative electrode material area along the width direction of the negative electrode sheet, 7. The cylindrical lithium-ion battery according to claim 1, characterized in that: The positive electrode tab region extends along the length direction of the positive electrode sheet, and the negative electrode tab region extends along the length direction of the negative electrode sheet.

8. The cylindrical lithium-ion battery according to claim 1, characterized in that: The winding core includes a starting end for starting winding and an end opposite to the starting end, wherein at the starting end, along the length direction of the positive electrode sheet, the length of the positive electrode material area beyond the positive electrode tab area is N1, and the length of the negative electrode material area beyond the negative electrode tab area is N2, 60mm≤N1≤140mm, 40mm≤N2≤100mm; at the end, along the length direction of the positive electrode sheet, the length of the positive electrode material area beyond the positive electrode tab area is N3, and the length of the negative electrode material area beyond the negative electrode tab area is N4, 40mm≤N3≤100mm, 30mm≤N4≤90mm.

9. The cylindrical lithium-ion battery according to claim 1, characterized in that: The height of the winding core is H3, the height of the cylindrical lithium-ion battery is H4, 90%≤H3 / H4≤98%, 65mm≤H3≤160mm.

10. The cylindrical lithium-ion battery according to claim 1, characterized in that: The thickness of the positive electrode collector disk is D3, the thickness of the negative electrode collector disk is D4, 0.1mm≤D3≤1mm, 0.1mm≤D4≤1mm, the height of the positive electrode flattening layer is H1, the height of the positive electrode flattening layer is the length from the outermost extension of the positive terminal to the ceramic area along the width direction of the positive electrode sheet, the height of the negative electrode flattening layer is H2, the height of the negative electrode flattening layer is the length from the outermost extension of the negative terminal to the negative electrode material area along the width direction of the positive electrode sheet, H1=-0.1175+3.55×D3-5×D3 2 +M3, H2=-0.1175+3.55×D4-5×D4 2 +M3, -0.15mm≤M3≤0.15mm.

11. The cylindrical lithium-ion battery according to claim 1, wherein in the positive electrode flattening layer, along the radial direction of the winding core, the hypotenuse of the positive electrode tab region located at the outermost extension of the positive electrode flattening layer forms an angle θ with the radius of the winding core, 20°≤θ≤90°.

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