Bare cell, cylindrical cell, and electric device

Abstract

The utility model discloses a kind of bare cell, cylindrical cell and electric equipment, bare cell is formed by the first pole piece, diaphragm and second pole piece of laminated arrangement along winding direction, the first pole piece is formed first lug from one end of the bare cell, the second pole piece is formed second lug from second end of the bare cell, in perpendicular to the direction of winding, the edge of the first lug is equipped with empty foil area, the surface of the first pole piece is equipped with active layer and heat insulation layer in proper order, the heat insulation layer is located between the empty foil area and the active layer;In laminated direction, at least a portion of the heat insulation layer is located between the first lug and the diaphragm.The bare cell of the utility model has the advantages of long service life, high safety performance.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and more specifically, to a bare battery cell, a cylindrical battery cell, and an electrical device. Background Technology

[0002] Currently, the core advantages of large cylindrical batteries lie in the improved charge-discharge performance, optimized safety, and reduced costs achieved through structural innovation and material breakthroughs. Among these, the full-tab structure design is the key to achieving low internal resistance and high-rate charge-discharge performance in large cylindrical cells. Full-tab technology typically requires leaving an uncoated foil area (i.e., tab) at one end of the battery core's electrode. After processing the tab, a laser welding process is used to connect the tab to a metal current collector, which is then connected to the corresponding polarity terminal or casing.

[0003] The negative electrode foil is typically made of copper foil, while the corresponding current collector may be made of copper, iron, or steel, all of which have high melting points. The separator between the positive and negative electrodes is usually composed of polymer materials, which are highly susceptible to shrinkage or even breakage under high temperatures. During the welding process of the negative electrode current collector, the temperature in the welding area is high, and the edge of the separator is close to the tab area, so it is very likely to shrink or even break due to heat.

[0004] Furthermore, the core is typically formed by stacking and winding a negative electrode sheet, a separator, a positive electrode sheet, and another separator. In a full-tab design, both the positive and negative electrode sheets are coated with a layer containing active material continuously on both sides of the foil along the winding direction, while leaving empty foil areas at the edges. During winding, the empty foil areas of the positive and negative electrode sheets are placed at both ends of the core. During the winding process, it is necessary to ensure that the negative electrode coating area completely covers the positive electrode coating area, and that the separators on both sides completely wrap the negative electrode coating area. At the same time, the length of the empty foil areas of the positive and negative electrode sheets exceeds the separator, which facilitates the subsequent welding of the current collector and the empty foil areas (i.e., the tabs).

[0005] After winding, at the negative end of the core, the copper foil and separator are separated by the coatings of the positive and negative electrode active materials. Combined with the stress generated during core winding, the copper foil and separator typically stand upright with a small gap, usually only a few hundred micrometers. Before welding the current collector in subsequent processes, the tabs need to be processed to facilitate welding. This process usually involves compressing or pushing down the tabs, either partially or entirely. During this process, due to the small gap between the copper foil and separator, and the extremely thin and low mechanical strength of the copper foil, contact between the copper foil and separator is very likely. During subsequent welding, because of the excellent thermal conductivity of the copper foil, the heat generated during welding can be conducted to the separator, causing it to shrink due to heat. This leads to localized separator failure, increasing the risk of self-discharge or even internal short circuits.

[0006] Furthermore, the shrinkage of the separator due to heat can cause a decrease in the battery's safety performance, posing a safety risk.

[0007] (1) The shrinkage of the separator will reduce the coating of the positive and negative electrodes, increasing the safety risk of the battery. If the separator shrinks further until it can no longer completely wrap the positive electrode, it will cause a short circuit inside the cell.

[0008] (2) Localized thermal shrinkage of the separator may reduce its strength at that point, increasing the risk of separator rupture after multiple battery cycles, leading to a short circuit within the cell.

[0009] In other words, under the full tab design, during the welding process of the negative tab and the negative current collector or the bottom cover with current collector function, the heat generated by welding is easily conducted to the diaphragm, which causes the diaphragm to shrink locally due to heat, affecting the safety performance of the cell. Utility Model Content

[0010] One objective of this invention is to provide a bare battery cell that can at least solve the technical problem in the prior art where the welding process of the tabs and current collectors easily leads to localized thermal shrinkage of the diaphragm.

[0011] Another objective of this utility model is to provide a cylindrical battery cell.

[0012] Another objective of this utility model is to provide an electrical device.

[0013] To achieve the above objectives, the present invention provides the following technical solution.

[0014] According to a first aspect embodiment of the present invention, the bare battery cell is formed by winding a first electrode, a separator, and a second electrode in a winding direction. The first electrode extends from one end of the bare battery cell and forms a first tab, and the second electrode extends from the second end of the bare battery cell and forms a second tab. In a direction perpendicular to the winding direction, the edge of the first tab is provided with a blank foil area. An active layer and a heat insulation layer are sequentially provided on the surface of the first electrode, and the heat insulation layer is located between the blank foil area and the active layer. In the stacking direction, at least a portion of the heat insulation layer is located between the first tab and the separator.

[0015] Optionally, the heat insulation layer is at least one of PVDF coating, PI coating, PAA coating, PBA coating, SBR coating, or CMC coating.

[0016] Optionally, the heat insulation layer contains dyes and / or color powders.

[0017] Optionally, the heat insulation layer contains at least one of boehmite, ceramic powder, titanium dioxide, or hollow glass microspheres.

[0018] Optionally, the active layer and the heat insulation layer have a spacing d1, 0≤d1≤1mm, perpendicular to the winding direction.

[0019] Optionally, in the direction perpendicular to the winding direction, the edge of the heat insulation layer near the empty foil area is flush with the edge of the diaphragm, or extends beyond the edge of the diaphragm, and there is a distance d2 between the edge of the heat insulation layer and the edge of the diaphragm, where 0≤d2≤2mm.

[0020] Optionally, in the stacking direction, the thickness of the insulation layer is h, where 5μm≤h≤50μm.

[0021] Optionally, the first electrode is a negative electrode and the second electrode is a positive electrode.

[0022] A cylindrical battery cell according to a second aspect of the present invention includes: a housing and a bare battery cell, wherein the bare battery cell is located inside the housing, and the bare battery cell is any of the bare battery cells described above.

[0023] The electrical equipment according to the third aspect of the present invention includes any of the cylindrical battery cells described above.

[0024] According to the bare battery cell of this utility model embodiment, the heat insulation layer has a heat insulation effect and can isolate the separator and the first tab, such as isolating the separator and the copper foil, to avoid direct contact between the first tab and the separator during processing, such as at the edge of the copper foil. This not only reduces or even eliminates the heat generated during the welding of the current collector and the tab from damaging the separator, but also reduces the safety risks of the battery cells produced after subsequent production. Furthermore, it can increase the power and spot area of ​​the laser used in the welding process of the current collector and the tab without damaging or with limited damage to the separator, thereby increasing the effective connection area produced by welding and reducing the internal resistance of the battery cells produced after subsequent production.

[0025] Other features and advantages of the present invention will become clear from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present invention and, together with their description, serve to explain the principles of the present invention.

[0027] Figure 1 This is a schematic diagram of the unfolded bare battery cell according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the unfolded bare battery cell according to another embodiment of the present invention;

[0029] Figure 3 This is a partial cross-sectional view of a bare battery cell according to an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the first tab bending to contact the diaphragm according to an embodiment of the present invention.

[0031] Attached icon number

[0032] Bare battery cell 100;

[0033] First electrode plate 10; First electrode tab 11; Empty foil area 12;

[0034] Diaphragm 20;

[0035] Second electrode plate 30; Second electrode tab 31;

[0036] Active layer 40;

[0037] Insulation layer 50. Detailed Implementation

[0038] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0039] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0040] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0041] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0042] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0043] The bare battery cell 100 according to an embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0044] like Figures 1 to 4As shown, the bare battery cell 100 according to an embodiment of this application is formed by winding a first electrode 10, a separator 20, and a second electrode 30 in a winding direction. The first electrode 10 extends from one end of the bare battery cell 100 and forms a first electrode tab 11, and the second electrode 30 extends from the second end of the bare battery cell 100 and forms a second electrode tab 31. In the direction perpendicular to the winding direction, the edge of the first electrode tab 11 is provided with a loose foil area 12. An active layer 40 and a heat insulation layer 50 are sequentially provided on the surface of the first electrode 10. The heat insulation layer 50 is located between the loose foil area 12 and the active layer 40. For ease of explanation, this direction can be defined as the first direction, such as... Figure 1 and Figure 2 As shown; in the stacking direction, at least a portion of the heat insulation layer 50 is located between the first tab 11 and the diaphragm 20. For ease of explanation, this direction can be defined as the second direction, such as... Figure 3 As shown.

[0045] In other words, the bare battery cell 100 according to the embodiments of this application mainly comprises a first electrode 10, a second electrode 30, and a separator 20. First, the first electrode 10, the separator 20, and the second electrode 30 are stacked, and then wound to obtain the bare battery cell 100. The number of first electrode 10, separator 20, and second electrode 30 can be multiple, which will not be elaborated here. One end of the bare battery cell 100 has a first tab 11 extending out, and the other end has a second tab 31 extending out. For example, the upper end of the bare battery cell 100 has a negative tab, and the lower end has a positive tab.

[0046] In this configuration, the edge of the first electrode tab 11 has a hollow foil area 12, perpendicular to the winding direction. For example, after winding, the uppermost end of the first electrode tab 11 has a hollow foil area 12. Furthermore, an active layer 40 is provided on the surface of the first electrode 10; for example, a negative electrode active material is provided on the surface of the negative electrode. A heat insulation layer 50 is also provided on the surface of the first electrode 10, and in the winding direction, the heat insulation layer 50 and the active layer 40 are arranged sequentially, meaning they are not overlapped. Additionally, in the stacking direction of the first electrode 10, the separator 20, and the second electrode 30, at least a portion of the heat insulation layer 50 is located between the first electrode tab 11 and the separator 20. For example, in the direction perpendicular to the winding direction, the active layer 40, the heat insulation layer 50, and the hollow foil area 12 are arranged sequentially.

[0047] During production, while or after the active slurry is coated on the first electrode 10 to obtain the active layer 40, a continuous heat-insulating coating is applied along the edge of the active slurry on the first electrode 10 in the winding direction to form the heat-insulating layer 50.

[0048] In this embodiment, the heat insulation layer 50 has a heat insulation effect, which can isolate the diaphragm 20 and the first tab 11, for example, isolate the diaphragm 20 and the copper foil, to avoid direct contact between the first tab 11 and the diaphragm 20 during the processing of the first tab 11, such as the edge of the copper foil, and prevent the copper foil from conducting heat and burning the diaphragm 20. This can not only reduce or even eliminate the heat generated during the welding of the current collector and the tab from damaging the diaphragm 20, reducing the safety risks of the battery cells produced after subsequent production; but also increase the power and spot area of ​​the laser used in the welding of the current collector and the tab without damaging or with limited damage to the diaphragm 20, increase the effective connection area generated by welding, reduce the internal resistance of the battery cells produced after subsequent production, and improve the processing feasibility of core welding.

[0049] According to one embodiment of this application, the heat insulation layer 50 is at least one of PVDF coating, PI coating, PAA coating, PBA coating, SBR coating, or CMC coating. That is, the heat insulation layer 50 can be a polymer coating, and its material may be one or a combination of several of PVDF, PI, PAA, PBA, and CMC, with a wide range of choices.

[0050] In some specific embodiments of this application, the heat insulation layer 50 is provided with dyes and / or color powders. That is to say, the polymer coating may not have dyes or color powders added or may selectively add dyes or color powders to meet the needs of different products.

[0051] According to one embodiment of this application, the heat insulation layer 50 contains at least one of boehmite, ceramic powder, titanium dioxide, or hollow glass microspheres. That is, the polymer coating may or may not contain fillers such as boehmite, ceramic powder, titanium dioxide, or hollow glass microspheres, which improve the heat insulation effect.

[0052] In some specific embodiments of this application, the active layer 40 and the heat insulation layer 50 have a spacing d1 perpendicular to the winding direction, where 0 ≤ d1 ≤ 1 mm, for example, d1 is 0 mm, 0.2 mm, 0.5 mm, 0.6 mm, 0.8 mm, or 1 mm. When d1 is 0 mm, the active layer 40 and the heat insulation layer 50 are arranged adjacent to each other. That is, the edge of the heat insulation layer 50 away from the empty foil area 12 can contact or have a gap with the edge of the active layer 40. In the stacking direction, the heat insulation layer 50 does not cover the active layer 40 or is mixed with it, i.e., 0 ≤ d1 ≤ 1 mm, for example, the heat insulation layer 50 does not cover the area where the negative electrode active material is located. In this embodiment, 0 ≤ d1 ≤ 1 mm is used, which can be controlled according to the product size and welding position, etc.

[0053] According to one embodiment of this application, in the direction perpendicular to the winding direction, the edge of the heat insulation layer 50 near the empty foil area 12 is flush with or extends beyond the edge of the separator 20. The edge of the heat insulation layer 50 and the edge of the separator 20 have a distance d2, where 0 ≤ d2 ≤ 2 mm. For example, d2 can be 0 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, or 2 mm. In other words, the edge of the heat insulation layer 50 away from the active layer 40 is flush with or extends beyond the separator 20 after winding, i.e., 0 ≤ d2 ≤ 2 mm. This can be adjusted according to the welding position and welding process to ensure the heat insulation effect.

[0054] In some specific embodiments of this application, the thickness of the heat insulation layer 50 in the stacking direction is h, where 5μm≤h≤50μm, for example, h is 5μm, 10μm, 15μm, 20μm, 30μm, 40μm or 50μm, etc. By using the heat insulation layer 50 with the above thickness h, the lifespan and performance of the separator 20 can be guaranteed without affecting the battery capacity and size.

[0055] According to one embodiment of this application, the first tab 11 is a negative tab and the second tab 31 is a positive tab. For example, a heat-insulating coating can be provided on the negative electrode sheet to isolate the copper foil and the diaphragm 20, so that the heat influence on the diaphragm 20 during the welding process of the current collector and the tab can be effectively reduced, thus ensuring the integrity of the diaphragm 20.

[0056] This application also discloses a cylindrical battery cell, including: a housing and a bare battery cell 100, wherein the bare battery cell 100 is located inside the housing, and the bare battery cell 100 is the bare battery cell 100 according to any of the above embodiments. Since the cylindrical battery cell of the embodiments of this application includes the bare battery cell 100 of any of the above embodiments, and the bare battery cell 100 has advantages such as a long service life of the separator 20, the cylindrical battery cell of the embodiments of this application also has the same advantages, which will not be elaborated here.

[0057] This application also discloses an electrical device including a cylindrical battery cell from any of the above embodiments. The electrical device of this application has advantages such as low safety performance.

[0058] In summary, the bare cell 100 according to the embodiments of this application is formed by winding a first electrode 10, a separator 20 and a second electrode 30 in a winding direction. The surface of the first electrode 10 is sequentially provided with an active layer 40 and a heat insulation layer 50. The heat insulation layer 50 is located between the empty foil area 12 and the active layer 40. By using the heat insulation layer 50, direct contact between the electrode tab and the separator 20 can be avoided during the processing of the electrode tab, and the heat generated during the welding of the current collector and the electrode tab can be reduced to reduce the damage to the separator 20 caused by heat.

[0059] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A bare cell, characterized by, The bare battery cell is formed by winding a first electrode, a separator, and a second electrode in a stacked manner along a winding direction. The first electrode extends from one end of the bare battery cell and forms a first tab, and the second electrode extends from the second end of the bare battery cell and forms a second tab. In the direction perpendicular to the winding, the edge of the first tab has a hollow foil area. An active layer and a heat insulation layer are sequentially provided on the surface of the first electrode, and the heat insulation layer is located between the hollow foil area and the active layer. In the stacking direction, at least a portion of the heat insulation layer is located between the first tab and the separator.

2. The bare cell of claim 1, wherein, The heat insulation layer is at least one of PVDF coating, PI coating, PAA coating, PBA coating, SBR coating or CMC coating.

3. The bare cell of claim 1, wherein, The insulation layer contains dyes and / or color powders.

4. The bare cell of claim 1, wherein, The heat insulation layer contains at least one of boehmite, ceramic powder, titanium dioxide, or hollow glass microspheres.

5. The bare cell of claim 1, wherein, The active layer and the heat insulation layer have a spacing d1, 0≤d1≤1mm, perpendicular to the winding direction.

6. The bare cell of claim 1, wherein, Perpendicular to the winding direction, the edge of the heat insulation layer near the empty foil area is flush with or extends beyond the edge of the diaphragm, and there is a distance d2 between the edge of the heat insulation layer and the edge of the diaphragm, where 0 ≤ d2 ≤ 2 mm.

7. The bare cell of claim 1, wherein, In the stacking direction, the thickness of the insulation layer is h, where 5μm≤h≤50μm.

8. The bare cell of claim 1, wherein, The first electrode is the negative electrode, and the second electrode is the positive electrode.

9. A cylindrical cell characterized by, include: A housing and a bare battery cell, wherein the bare battery cell is located within the housing and is a bare battery cell according to any one of claims 1-8.

10. An electric device, characterized by Including the cylindrical battery cell as described in claim 9.

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