Lithium ion battery roll core and battery cell

Abstract

The utility model relates to the technical field of lithium batteries, in particular to a lithium ion battery roll core and a battery cell, the roll core comprises a positive plate, a negative plate and a diaphragm, the positive plate comprises a coated area I and an uncoated area I, and a plurality of notches I are formed in the uncoated area I; the negative plate comprises a coating area II and an uncoated area II, and a plurality of notches II are formed in the uncoated area II; the positive plate, the diaphragm and the negative plate are stacked and wound into a flat shape with a runway-shaped cross section, the uncoated areas I and the uncoated areas II are distributed at different ends, the plurality of notches I are stacked to form two oppositely arranged grooves I, the plurality of notches II are stacked to form two oppositely arranged grooves II, and the uncoated areas I and the uncoated areas II are stacked to form two oppositely arranged grooves II. And the groove I and the groove II are sectors with the same structure and size and are positioned in the middle of the runway-shaped arc-shaped section. The lithium ion battery roll core and the battery cell provided by the utility model are high in energy density, good in safety, long in service life, low in cost and high in production efficiency.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, in particular to a lithium-ion battery core and an electric core. Background Art

[0002] Lithium batteries are an essential part of electric vehicles. They not only determine the driving range and performance of electric vehicles but also directly relate to the environmental protection, energy conservation of electric vehicles and the development direction of the entire industry. As the smallest energy storage unit of a lithium battery, the electric core is the basis of the entire battery system. Multiple electric cores are combined into a battery module through series or parallel connection, and then form a battery pack. The energy density of the electric core determines how much electrical energy the battery can store. An electric core with a high energy density can enable the battery to have a longer driving range and a smaller volume.

[0003] Square lithium batteries are a relatively mainstream type of battery in electric vehicles. Models such as Roewe ERX5, NIO, and Li ONE use this type of battery. It is generally rectangular in shape, with two flat elliptical cores obtained by winding placed side by side along the height direction of the battery. The outer shell is generally an aluminum shell formed by stamping. The positive and negative electrode terminals and the pressure relief valve are all located at the top. The square lithium battery has a relatively high energy density. It can store more electrical energy in the same volume. However, during the manufacturing process of the flat elliptical core, there are problems such as complex tension control and poor alignment, which are not conducive to improving the production efficiency and reducing the manufacturing cost of the battery.

[0004] Therefore, this application is proposed. Content of the Utility Model

[0005] In view of the above-mentioned shortcomings of the prior art, the utility model provides a lithium-ion battery with rapid temperature control.

[0006] To achieve the above purpose, the main technical solutions adopted by the utility model include:

[0007] On the one hand, the utility model proposes a lithium-ion battery core, which includes a positive electrode sheet, a negative electrode sheet and a separator;

[0008] The positive electrode sheet includes a positive current collector and a positive active material layer. A part of the positive current collector is coated with the positive active material to form a coated area Ⅰ, and another part is not coated with the positive active material to form an uncoated area Ⅰ. A plurality of notches Ⅰ are opened on the uncoated area Ⅰ;

[0009] The negative electrode sheet includes a negative current collector and a negative active material layer. A part of the negative current collector is coated with the negative active material to form a coated area Ⅱ, and another part is not coated with the negative active material to form an uncoated area Ⅱ. A plurality of notches Ⅱ are opened on the uncoated area Ⅱ;

[0010] The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound into a flat shape with a runway-shaped cross-section. The uncoated area I and the uncoated area II are distributed at different ends and form the positive electrode tab and the negative electrode tab respectively. A plurality of notches I are stacked to form two oppositely arranged grooves I, and a plurality of notches II are stacked to form two oppositely arranged grooves II. Both the groove I and the groove II are sectors with the same structure and size and are both located in the middle of the arc segment of the runway shape.

[0011] Preferably, the central angle α of the sector satisfies: 10° ≤ α ≤ 180°, for example, α can be 10°, 15°, 20°, 30°, 50°, 100°, 120°, 150°, 180°, etc.; the arc angle radius R1 of the arc segments on both sides of the groove I satisfies: 0 mm < R1 ≤ 100 mm, for example, R1 can be 2 mm, 5 mm, 10 mm, 15 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, etc.

[0012] On the basis that the positive electrode tab and the negative electrode tab have the same structure and size, preferably, the depth of the groove I is the same as the height of the positive electrode tab.

[0013] Preferably, the areas of the positive electrode tab and the negative electrode tab located in the arc segment can be partially cut or fully cut to form an earless area.

[0014] On the other hand, the present invention proposes a lithium-ion battery cell, including the above-mentioned core.

[0015] Preferably, the longitudinal cross-section of the mandrel has a runway-shaped structure, and the arc angle radius R2 and the radian β of the arc segment of the runway-shaped structure satisfy: 0 < R2 ≤ 100 mm, 10° ≤ β ≤ 180°.

[0016] Preferably, the length L2, height H2, and thickness T2 of the mandrel satisfy: 10 mm ≤ L2 ≤ 2000 mm, 10 mm ≤ H2 ≤ 200 mm, 3 mm ≤ T2 ≤ 200 mm.

[0017] Preferably, positioning holes are provided in the middle of the left and right ends of the mandrel, and the radius R3 of the positioning holes satisfies 1 mm ≤ R3 ≤ 100 mm, for example, R3 can be 1 mm, 2 mm, 5 mm, 10 mm, 15 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, etc.

[0018] Preferably, the length L1, height H1, and thickness T1 of the battery cell satisfy: 10 mm ≤ L1 ≤ 2000 mm, 10 mm ≤ H1 ≤ 200 mm, 10 mm ≤ T1 ≤ 200 mm.

[0019] Preferably, the height of the positive electrode tab and the negative electrode tab is 3-30 mm.

[0020] Compared with the prior art, the present utility model has at least the following beneficial effects:

[0021] (1) The runway-shaped core design combines a long core with a thick electrode sheet, reducing the proportion of non-active substances such as current collectors and structural components, improving the energy density, and reducing the material cost;

[0022] (2) A pair of grooves oppositely arranged at each end of the core helps to maximize the elimination of stress generated by tab folding, can significantly reduce the difficulty of tension control during core production, improve the alignment, and is of great significance for improving the core production process. In addition, it can also improve the performance of lithium batteries, enhance the safety of lithium batteries, and extend the life of lithium batteries;

[0023] (3) The design structure of the full-tab core significantly enhances the overcurrent capacity, helps to improve the power and energy density, enhances the charge and discharge performance, and ensures the safety of lithium batteries;

[0024] (4) The obtained battery cell can meet the system integration requirements, helps to build a battery PACK, and improves the overall energy density of the battery PACK. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings 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.

[0026] Figure 1 It is a three-dimensional structure schematic diagram of the core proposed by the present utility model;

[0027] Figure 2 is Figure 1 the top view of;

[0028] Figure 3 is Figure 1 the structure schematic diagram of the positive electrode sheet in;

[0029] Figure 4 is Figure 1 the structure schematic diagram of the negative electrode sheet in;

[0030] Figure 5 It is a three-dimensional structure schematic of the battery cell proposed by the present utility model Figure 1 ;

[0031] Figure 6 is Figure 5 the top view of;

[0032] Figure 7 Schematic diagram of the three-dimensional structure of the battery cell proposed by the present utility model Figure 2 ;

[0033] Figure 8 is Figure 5 Schematic diagram of the three-dimensional structure of the central core rod;

[0034] Figure 9 is Figure 8 left view of

[0035] In the figure: 1, positive electrode sheet; 11, coating area I; 12, uncoated area I; 121, notch I; 2, negative electrode sheet; 21, coating area II; 22, uncoated area II; 221, notch II; 3, groove I; 4, core rod; 41, positioning hole; A, inner side of the tab; B, outside of the tab; C, tab area. Specific embodiments

[0036] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a 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 those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0037] It should be noted that: the components or structures not described in detail below all adopt the conventional technical means in the art.

[0038] As Figures 1-9 collectively shown:

[0039] On the one hand, the present utility model proposes a lithium-ion battery core, including a positive electrode sheet 1, a negative electrode sheet 2 and a separator; the positive electrode sheet 1 includes a positive electrode current collector and a positive electrode active material layer, a part of the positive electrode current collector is coated with the positive electrode active material to form a coating area I 11, and another part is not coated with the positive electrode active material to form an uncoated area I 12. A plurality of notches I 121 are provided on the uncoated area I 12; the negative electrode sheet 2 includes a negative electrode current collector and a negative electrode active material layer, a part of the negative electrode current collector is coated with the negative electrode active material to form a coating area II 21, and another part is not coated with the negative electrode active material to form an uncoated area II 22. A plurality of notches II 221 are provided on the uncoated area II 22; the positive electrode sheet 1, the separator, and the negative electrode sheet 2 are stacked and wound into a flat shape with a runway-shaped cross section. The uncoated area I 12 and the uncoated area II 22 are distributed at different ends and respectively form a positive electrode tab and a negative electrode tab. After a plurality of notches I 121 are stacked, two relatively arranged grooves I 3 are formed. After a plurality of notches II 221 are stacked, two relatively arranged grooves II are formed. The groove I 3 and the groove II are both sectors with the same structure and size and are both located in the middle of the arc section of the runway shape.

[0040] The provision of the first groove 3 has at least the following functions: (1) It can effectively eliminate the stress generated during the folding of the tab, which not only helps to reduce the defective rate on the production line caused by tab folding problems, improve production efficiency and product quality, but also has a positive impact on enhancing battery performance, improving battery safety, and extending battery life. (2) When injecting the electrolyte, the positive electrode sheet 1 and the negative electrode sheet 2 can quickly penetrate and absorb the electrolyte through the two relatively arranged first grooves 3 and the two relatively arranged second grooves, improving the speed, consistency, and uniformity of the penetration and absorption of the electrolyte by the positive electrode sheet 1 and the negative electrode sheet 2, shortening the injection time, increasing the cycle life of the lithium battery, and improving the production capacity of the lithium battery.

[0041] Compared with the prior art, a pair of relatively arranged grooves at each end of the core of the present utility model helps to maximize the elimination of the stress generated by tab folding, solves the problems of complex tension regulation and poor alignment during the production of the core in the prior art, helps to improve the battery production efficiency, and is of great significance for improving the battery production process, enhancing the performance of the lithium battery, improving the safety of the lithium battery, and extending the life of the lithium battery. In addition, through the racetrack-shaped core design, the combination of the long core and the thick electrode tab reduces the proportion of inactive substances such as current collectors and structural components, increases the energy density, and reduces the material cost.

[0042] As a preferred technical solution, in another embodiment of the present utility model, the central angle α of the sector satisfies: 10° ≤ α ≤ 180°, and the arc angle radius R1 of the arc segments on both sides of the first groove 3 satisfies: 0 mm < R1 ≤ 100 mm.

[0043] As a preferred technical solution, in another embodiment of the present utility model, the depth of the first groove 3 is the same as the height of the positive tab.

[0044] Under the above technical parameters, the provision of the first groove 3 can not only improve the electrolyte penetration speed and improve the wettability of the positive and negative electrode sheets, but also does not significantly affect the conductivity of the positive electrode part and the negative electrode part.

[0045] It should be noted that: The preparation method of the battery core of the lithium battery proposed by the present utility model is the same as that of the prior art. First, the groove specifications are designed, and then the dimensions, shapes, and positions of the corresponding notches are designed according to the groove specifications. Then, the uncoated areas of the positive electrode sheet and the negative electrode sheet are laser die-cut. After that, the positive electrode sheet, the negative electrode sheet, and the separator are stacked and wound around the outer periphery of the mandrel so that the notches are sequentially stacked to form the corresponding grooves. Finally, the two ends of the wound core are flattened or kneaded.

[0046] As a preferred technical solution, in another embodiment of the present utility model, the area of the positive tab and the negative tab located in the arc segment is cut to form a tabless area.

[0047] As shown Figure 2 in the figure: That is, the red-frame part is the tab area C that must be retained. The arc segments on both sides of the groove I3 can be partially or completely cut.

[0048] In addition, for the tab area C, it can be formed by completely retaining the uncoated area I12, i.e., the blank foil. The full tab helps to enhance the overcurrent capacity, improve the power density, rate performance, and ensure safety. It can also be formed by laser-partially cutting the edge of the blank foil into multiple single tabs in a serrated or trapezoidal shape. Moreover, for the convenience of winding, the height of the single tab gradually increases from small to large; in order to avoid potential interference and short-circuit risks, there is no tab on the inner side A of the tab close to the mandrel 4; for optimizing the tab layout and connection, improving the connection efficiency, and avoiding occlusion, the outside B of the tab is stepped. The stepped design can also reduce the internal resistance, avoid short circuits, disperse heat, increase the battery capacity, and is convenient for processing and reducing the scrap rate.

[0049] On the other hand, the present utility model provides a lithium-ion battery cell core, including the above-mentioned lithium-ion battery winding core.

[0050] As a preferred technical solution, in another embodiment of the present utility model, the longitudinal section of the mandrel 4 has a runway-shaped structure, and the arc radius R2 and radian β of the arc segment of the runway-shaped structure satisfy: 0 < R2 ≤ 100 mm, 10° ≤ β ≤ 180°.

[0051] As a preferred technical solution, in another embodiment of the present utility model, the length L2, height H2, and thickness T2 of the mandrel 4 satisfy: 10 mm ≤ L2 ≤ 2000 mm, 10 mm ≤ H2 ≤ 200 mm, 3 mm ≤ T2 ≤ 200 mm.

[0052] The mandrel 4 plays a supporting and guiding role during the winding process of the winding core. When the mandrel 4 meets the above requirements, combined with the design of the notch I121 and notch II221, the tension during the winding of the positive and negative electrode plates and the separator is easy to control, the combination between the positive and negative electrode plates and the separator is tight, the flatness of the battery cell is high, and the yield and performance stability of the battery cell are high.

[0053] As a preferred technical solution, in another embodiment of the present utility model, positioning holes 41 are provided in the middle of the left and right ends of the mandrel 4, and the radius R3 of the positioning holes 41 satisfies 1 mm ≤ R3 ≤ 100 mm.

[0054] The positioning holes 41 are mainly provided to ensure the stability and safety of the battery cell during the manufacturing process. They can not only ensure the accurate position of the mandrel 4 during the winding process, prevent the mandrel 4 from shifting or rotating during the winding process, so as to ensure that the positive and negative electrode sheets and the separator can be tightly wound together in a predetermined manner, but also help to control the consistency of the size and shape of the battery cell, reduce the performance fluctuations of the battery cell caused by the minor differences in the manufacturing process, and also facilitate the assembly and detection of the battery cell.

[0055] As a preferred technical solution, in another embodiment of the present utility model, the length L1, height H1, and thickness T1 of the battery cell satisfy: 10 mm ≤ L1 ≤ 2000 mm, 10 mm ≤ H1 ≤ 200 mm, 10 mm ≤ T1 ≤ 200 mm.

[0056] For a battery cell that meets the above specification requirements, whether in terms of weight, thermal management, or safety performance, it can meet the system integration requirements, contribute to the construction of the battery PACK, and improve the overall energy density of the battery PACK.

[0057] As a preferred technical solution, in another embodiment of the present utility model, the heights of the positive electrode tab and the negative electrode tab are 3 - 30 mm.

[0058] The tab height has a significant impact on the performance and safety of the battery cell. For example, if the tab height is too high, it may cause the current flow path in the tab to become longer, increasing both the resistance and affecting heat dissipation, and also increasing costs; if the tab height is too low, it may cause the connection between the tab and other components to be not firm enough, easily loosening or even falling off, and the insecure connection will also indirectly increase the internal resistance of the battery and limit the current, resulting in the battery not being able to meet the requirements during high-rate charge and discharge. In this application, for the racetrack-shaped flat battery cell with length L1, height H1, and thickness T1 satisfying: 10 mm ≤ L1 ≤ 2000 mm, 10 mm ≤ H1 ≤ 200 mm, 10 mm ≤ T1 ≤ 200 mm, under this condition, the heights of the positive electrode tab and the negative electrode tab are preferably 3 - 30 mm.

[0059] In summary, the present utility model combines a long core with a thick electrode tab through a runway-shaped core design, reducing the proportion of inactive substances such as current collectors and structural components, improving the energy density, and reducing the material cost. A pair of grooves oppositely arranged at each end of the core helps to maximize the elimination of stress generated by ear folding, significantly reducing the difficulty of tension control during core production, improving the alignment, and being of great significance for improving the core production process. In addition, it can also improve the performance of lithium batteries, enhance the safety of lithium batteries, and extend the service life of lithium batteries. The design structure of the full ear significantly enhances the overcurrent capacity, helps to improve the power and energy density, enhances the charge and discharge performance, and ensures the safety of lithium batteries. The obtained lithium-ion battery cell can meet the system integration requirements, helps to construct a battery PACK, and improves the overall energy density of the battery PACK.

[0060] Although the embodiments of the present utility model have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present utility model. Those of ordinary skill in the art can make changes, modifications, substitutions, and deformations to the above embodiments within the scope of the present utility model. In addition, without contradiction, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples.

Claims

1. A lithium-ion battery core, characterized in that: It comprises a positive electrode sheet (1), a negative electrode sheet (2) and a separator; The positive electrode sheet (1) comprises a positive electrode current collector and a positive electrode active material layer, wherein a portion of the positive electrode current collector is coated with a positive electrode active material to form a coated region I (11), and another portion is not coated with a positive electrode active material to form an uncoated region I (12), and a plurality of notches I (121) are provided on the uncoated region I (12); The negative electrode sheet (2) comprises a negative electrode current collector and a negative electrode active material layer, wherein a portion of the negative electrode current collector is coated with the negative electrode active material to form a coated area II (21), and another portion is not coated with the negative electrode active material to form an uncoated area II (22), and a plurality of notches II (221) are provided on the uncoated area II (22); The positive electrode sheet (1), the separator, and the negative electrode sheet (2) are stacked and wound into a flat shape with a runway-shaped cross section. The uncoated area I (12) and the uncoated area II (22) are arranged at opposite ends and form a positive electrode ear and a negative electrode ear respectively. A plurality of notches I (121) are stacked to form two oppositely arranged grooves I (3). A plurality of notches II (221) are stacked to form two oppositely arranged grooves II. The grooves I (3) and II are both fan-shaped with the same structure and size and are both located in the middle of the arc segment of the runway shape.

2. The lithium-ion battery roll core according to claim 1, characterized in that: The central angle α of the sector satisfies: 10°≤α≤180°, and the arc radius R1 of the arc segments on both sides of the groove I (3) satisfies: 0mm<R1≤100mm.

3. The lithium-ion battery roll core according to claim 1, characterized in that: The depth of the groove I (3) is the same as the height of the positive electrode tab.

4. The lithium-ion battery roll core according to any one of claims 1 to 3, characterized in that: The area where the positive electrode tab and the negative electrode tab are located in the arc segment can be partially or completely cut to form a tab-free area.

5. A lithium-ion battery cell, characterized in that: The invention comprises a lithium-ion battery roll core as claimed in claim 1.

6. The lithium-ion battery cell according to claim 5, characterized in that: The longitudinal cross section of the core rod (4) is a racetrack-shaped structure, and the arc angle radius R2 and the arc angle β of the arc segment of the racetrack-shaped structure satisfy the following conditions: 0<R2≤100mm, 10°≤β≤180°.

7. The lithium-ion battery cell according to claim 5, characterized in that: The length L2, height H2 and thickness T2 of the core rod (4) satisfy the following conditions: 10 mm ≤ L2 ≤ 2000 mm, 10 mm ≤ H2 ≤ 200 mm, and 3 mm ≤ T2 ≤ 200 mm.

8. The lithium-ion battery cell according to claim 5, characterized in that: Positioning holes (41) are provided in the middle of the left and right ends of the core rod (4), and the radius R3 of the positioning hole (41) satisfies 1mm≤R3≤100mm.

9. The lithium-ion battery cell according to claim 5, characterized in that: The length L1, height H1 and thickness T1 of the battery core satisfy: 10mm≤L1≤2000mm, 10mm≤H1≤200mm, 10mm≤T1≤200mm.

10. The lithium-ion battery cell according to claim 9, characterized in that: The height of the positive electrode tab and the negative electrode tab is 3-30 mm.

Images