Battery cell assembly and battery

Abstract

The utility model discloses a kind of electric core assembly and battery, including roll core unit, the cross section of roll core unit is rectangle, roll core unit includes at least two roll cores, the roll core includes sequentially wound first pole piece, diaphragm, second pole piece, the width of first pole piece corresponding first lug is all same, the width of second pole piece corresponding second lug is all same, and the lug of same polarity is connected in parallel;The number of roll core unit is one or more, when the number of roll core unit is multiple, multiple roll core unit is stacked and is formed after heat pressing electric core assembly.The utility model sets up the cross section of roll core unit as rectangle structure, so that the last formed electric core assembly is rectangle structure, perfectly fills four corners of rectangular shell, almost eliminates all invalid gap, maximally utilizes packaging space, to significantly improve the volumetric energy density of electric core.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, specifically to a cell assembly and a battery. Background Technology

[0002] In the core structure of wound lithium-ion batteries, the electrodes used in the core are usually long sheet-like structures. The longer the electrode, the more active material can be coated on its surface, which can increase the cell capacity. Longer electrodes can also prevent excessive cycle expansion and capacity decay caused by excessive electrode rebound. However, when the electrodes are formed into a core, they are bent after being wound. Along the thickness direction of the core, multiple straight segments are arranged roughly in parallel, and along the width direction of the core, multiple arc segments are arranged concentrically. This traditional structure limits the improvement of battery capacity and energy density, and has the following significant drawbacks: First, the space around the core is wasted: such as... Figure 1 As shown, a conventional wound battery cell includes a positive electrode (first electrode), a negative electrode (second electrode), and a separator. The cell is formed by winding these materials together. When this wound core is placed in a square aluminum-plastic film punch, there are large gaps between the core and the square outer shell. These gaps cannot accommodate active materials, resulting in low volumetric energy density. Second: Reliability bottleneck: Traditional battery cells typically use a single tab lead-out method. If a tab, tab solder joint, or part of the electrode fails during manufacturing or use (such as a micro-short circuit, breakage, lithium plating piercing the separator), it will cause the entire current loop to be interrupted or performance to degrade sharply, leading to the failure of the entire battery cell. This "one-point failure, overall scrap" mode reduces the utilization rate and overall lifespan of the battery cell and increases system costs. To solve this problem, there are two main solutions in the existing technology: one is to directly press and mold a single core into a square shape, but this method is very easy to generate huge stress inside the core, causing the separator to stretch and thin, the electrode powder to fall off or even break, seriously endangering the safety and life of the battery; the other is to use a stacking process, but its production efficiency is far lower than that of winding and the cost is high.

[0003] Therefore, there is an urgent need in this field for an innovative cell structure design that can effectively fill the space around the core with active material while ensuring battery safety and cycle life, thereby improving space utilization and energy density. Utility Model Content

[0004] This utility model addresses the problems in the prior art and aims to solve at least one technical problem. It discloses a battery cell assembly and a battery. The cross-section of the core unit is set to a rectangular structure, so that the final battery cell assembly is a rectangular structure, which perfectly fills the four corners of the rectangular shell, almost eliminating all ineffective gaps, maximizing the use of the packaging space, and thus significantly improving the volumetric energy density of the battery cell.

[0005] This utility model is achieved through the following technical solution: This utility model first provides a battery cell assembly, including a core unit with a rectangular cross-section. The core unit includes at least two cores, each core including a first electrode, a diaphragm, and a second electrode wound sequentially. The widths of the first tabs corresponding to the first electrode are all the same, and the widths of the second tabs corresponding to the second electrode are all the same. Tabs with the same polarity are connected in parallel. The number of core units can be one or more. When the number of core units is multiple, the multiple core units are stacked and hot-pressed to form a battery cell assembly.

[0006] As a further embodiment, the first electrode sheet includes a first double-sided fabric area, a first single-sided fabric area, a first double-sided fabric area, and a first electrode tab. The penultimate fold and half of the second-to-last fold of the first electrode sheet constitute the second double-sided fabric area, the remaining half of the second-to-last fold constitutes the first single-sided fabric area, and the rest of the first electrode sheet constitutes the first double-sided fabric area. The length ratio of the single-sided area to the second double-sided fabric area of ​​the first electrode sheet is 1:3. The second electrode sheet includes a second electrode sheet foil area, a second electrode sheet single fabric area, a second electrode sheet double fabric area, and a second electrode tab. The first fold of the second electrode sheet is the second electrode sheet foil area, the second and third folds of the second electrode sheet are the second electrode sheet single fabric areas, and the remaining part of the second electrode sheet is the second electrode sheet double fabric area. The length ratio of the second electrode sheet foil area to the second electrode sheet single fabric area is 1:2.

[0007] As a further embodiment, the core unit includes a first core and a second core. The first core includes a first electrode sheet, a diaphragm, and a second electrode sheet wound sequentially. The first electrode sheet includes a first double-sided fabric area, a first single-sided fabric area, and a first double-sided fabric area wound sequentially. The first double-sided fabric area of ​​the first electrode sheet is also welded with a first electrode tab. The second electrode sheet includes a second electrode foil area, a second single-sided fabric area, and a second double-sided fabric area wound sequentially. The second double-sided fabric area of ​​the second electrode sheet is also welded with a second electrode tab. The second core includes a third electrode sheet, a core diaphragm, and a fourth electrode sheet wound sequentially. The third electrode sheet includes a third electrode sheet double-sided fabric area and a third electrode tab welded thereon. The fourth electrode sheet includes a fourth electrode sheet foil area, a fourth electrode sheet first single-sided fabric area, a fourth electrode sheet first double-sided fabric area, a fourth electrode sheet second single-sided fabric area, and a fourth electrode sheet second double-sided fabric area wound sequentially, wherein the fourth electrode tab is welded to the fourth electrode sheet first double-sided fabric area.

[0008] As a further embodiment, the core unit includes a first core and a second core that are nested together to form a rectangle after hot pressing, and both the first core and the second core have a U-shaped structure after hot pressing. As a further embodiment, the single-fabric area of ​​the first electrode does not form a joint surface with the second core, the second double-fabric area of ​​the first electrode forms a joint surface with the second core, and the two are separated by a diaphragm; the second single-fabric area of ​​the fourth electrode does not form a joint surface with the first core, the second double-fabric area of ​​the fourth electrode forms a joint surface with the first core, and the two are separated by a diaphragm. As a further option, the thickness of both the first core and the second core is ≤3.5mm; As a further embodiment, the structure of the first core comprises a first arm, a first connecting segment, and a second arm connected vertically in sequence, with a first electrode tab on the second arm and a second electrode tab on the first arm. The length of the first arm is A1, and the thickness is B1; the length of the first connecting segment is A2, and the thickness is B2; the length of the second arm is A3, and the thickness is B3, where A2 = B3. The structure of the second core comprises a third arm, a second connecting segment, and a fourth arm connected vertically in sequence, with a third electrode tab on the fourth arm and a fourth electrode tab on the third arm. The length of the third arm is A4, and the thickness is B4; the length of the second connecting segment is A5, and the thickness is B5; the length of the fourth arm is A6, and the thickness is B6; where B2 = B4, B5 = B1, B6 = A5, and A6 = A3 = A2 + A4 = A5 + A1.

[0009] As a further embodiment, the core unit also includes a diaphragm to prevent short circuits between the two cores. When the outermost layer of the core is not a diaphragm, a diaphragm is inserted between the first core and the second core, and the diaphragm covers at least the mating surface of the first core and the second core.

[0010] As a further option, a positive or negative electrode coating is added to the bonding surface between two adjacent core units, and the positive and negative electrode coatings are separated by a diaphragm.

[0011] As a further embodiment, the core unit includes two first cores and one second core. Both the first core and the second core are U-shaped structures. The two arms of the first core are not equal in length, while the two arms of the second core are equal in length. The second core is located in the middle. There is no positive electrode coating on the joint surface between the two first cores. The outermost positive electrode coating of the first core and the outermost negative electrode coating of the second core are separated by a diaphragm to form a joint surface.

[0012] As a further embodiment, the core unit includes a first core and a second core, both of which are L-shaped. The outermost layer of the first core and the second core is a diaphragm after they are nested together. The outermost positive electrode coating of the first core and the outermost negative electrode coating of the second core form a bonding surface through the diaphragm.

[0013] As a further solution, after the core units are stacked and arranged in a set order, the tabs of the same polarity are welded to form a tab welding area; As a further option, multiple soft tabs of the same polarity are welded together to form a soft tab bundle, and a hard tab is welded onto the soft tab bundle.

[0014] This utility model also provides a battery, including a rectangular casing and the cell assembly encapsulated therein.

[0015] The features and beneficial effects of this utility model are as follows: (1) The present invention sets the cross-section of the core unit to a rectangular structure, so that the final battery cell assembly is a rectangular structure, which perfectly fills the four corners of the rectangular shell, almost eliminates all invalid gaps, maximizes the use of the packaging space, and thus significantly improves the volumetric energy density of the battery cell.

[0016] (2) This utility model adopts a method of pre-pressing and then combining multiple small cores separately. The small cores are easier to deform, and the internal stress and electrode damage risk are much less than those of directly pressing large cores, which better ensures the cycle life and safety of the battery cell.

[0017] (3) This utility model adopts a multi-tab parallel connection, which greatly reduces the internal resistance of the entire cell and is conducive to improving the rate charge and discharge performance and thermal management performance of the battery. Multiple core units are stacked and connected in parallel, so that if one core unit fails, the entire battery will not be paralyzed instantly, and the system reliability is higher. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The prior art cell structure described in the background art of this utility model; Figure 2 This is a schematic diagram of the structure of the first core as described in an embodiment of the present invention; Figure 3 This is a schematic diagram of the first electrode sheet according to an embodiment of the present utility model; Figure 4 This is a schematic diagram of the second electrode plate according to an embodiment of the present utility model; Figure 5 This is a schematic diagram of the second core as described in an embodiment of the present utility model; Figure 6 This is a schematic diagram of the third electrode plate according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the fourth electrode plate according to an embodiment of the present invention; Figure 8 This is a schematic diagram showing that the first core of the present invention is hot-pressed into a U-shape according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the first electrode plate being hot-pressed into a U-shape according to an embodiment of the present invention; Figure 10 This is a schematic diagram showing that the second electrode sheet of this utility model is hot-pressed into a U-shape according to an embodiment of the present invention; Figure 11 This is a schematic diagram showing that the second core of the present invention is hot-pressed into a U-shape according to an embodiment of the present invention; Figure 12 This is a schematic diagram of the third electrode plate being hot-pressed into a U-shape according to an embodiment of the present invention; Figure 13 This is a schematic diagram showing that the fourth electrode plate of this utility model is hot-pressed into a U-shape according to an embodiment of the present invention; Figure 14 This is a schematic diagram of a core unit according to an embodiment of the present invention where the core is U-shaped; Figure 15 This is a schematic diagram of the polarity coating applied inside the diaphragm of the core unit in an embodiment of the present invention, where the core is U-shaped. Figure 1 ; Figure 16 This is a schematic diagram of the polarity coating applied inside the diaphragm of the core unit in an embodiment of the present invention, where the core is U-shaped. Figure 2 ; Figure 17 This is a schematic diagram of the polarity coating applied inside the diaphragm of the core unit in an embodiment of the present invention, where the core is U-shaped. Figure 3 ; Figure 18 This is a schematic diagram of a core assembly according to an embodiment of the present invention, where the core is U-shaped. Figure 1 ; Figure 19 This is a schematic diagram of a core assembly according to an embodiment of the present invention, where the core is U-shaped. Figure 2 ; Figure 20 This is a schematic diagram of a core unit according to another embodiment of the present invention, where the core is U-shaped; Figure 21 This is a schematic diagram of a core assembly according to another embodiment of the present invention, where the core is U-shaped; Figure 22 This is a schematic diagram of the core unit described in an embodiment of the present invention where the core is L-shaped; Figure 23 This is a schematic diagram of the core assembly described in an embodiment of the present invention where the core is L-shaped. Figure 1 ; Figure 24 This is a schematic diagram of the polarity coating applied inside the diaphragm of the core unit in an embodiment of the present invention where the core is L-shaped. Figure 1 ; Figure 25This is a schematic diagram of the polarity coating applied inside the diaphragm of the core unit in an embodiment of the present invention where the core is L-shaped. Figure 2 ; Figure 26 This is a schematic diagram of the polarity coating applied inside the diaphragm of the core unit in an embodiment of the present invention where the core is L-shaped. Figure 3 ; Figure 27 This is a schematic diagram of the core assembly described in an embodiment of the present invention where the core is L-shaped. Figure 2 ; Figure 28 This is one of the electrode tab connection methods described in an embodiment of the present invention where the core is L-shaped; Figure 29 This is the second connection method for the electrode lugs described in an embodiment of the present invention where the core is L-shaped.

[0020] Explanation of reference numerals in the attached figures: 1-First electrode; 11-First electrode, first double-fabric area; 12-First electrode, single-fabric area; 13-First electrode, second double-fabric area; 14-First electrode tab; 15-First arm; 16-First connecting section; 17-Second arm; 2-Second electrode; 21-Second electrode, foil area; 22-Second electrode, single-fabric area; 23-Second electrode, double-fabric area; 24-Second electrode tab; 3-September; 4-Third electrode; 41-Third electrode, double-fabric area; 42-Third electrode tab; 43-First electrode, double-fabric area; 44-Second electrode tab; 5-Separator; 6-Second electrode; 7-Second electrode; 8-Second electrode; 9-Second electrode; 10-Second electrode; 11-First electrode, first double-fabric area; 12-First electrode, single-fabric area; 13-First electrode, second double-fabric area; 14-Second electrode tab; 15-First arm; 16-First connecting section; 17-Second arm; 18-Second arm; 19-Second electrode; 20-Second electrode; 21-Second electrode, foil area; 22-Second electrode, single-fabric area; 23-Second electrode, double-fabric area; 24-Second electrode tab; 19-Second electrode; 20-Second electrode; 20-Second electrode; 21-Second electrode, foil area; 22-Second electrode, single-fabric area; 23-Second electrode; 24-Second electrode tab; 25-Second electrode; 26-Second electrode; 2 Three arms; 44-Second connecting section; 45-Fourth arm; 5-Fourth electrode; 51-Fourth electrode foil area; 52-First single-layer fabric area of ​​the fourth electrode; 53-First double-layer fabric area of ​​the fourth electrode; 54-Second single-layer fabric area of ​​the fourth electrode; 55-Second double-layer fabric area of ​​the fourth electrode; 56-Fourth electrode tab; 6-Core diaphragm; 7-Shell; X-Positive electrode coating; Y-Negative electrode coating; S-Core unit; 8-Soft electrode tab; 9-Soft electrode tab bundle; 10-Hard electrode tab; 101-Soft electrode tab welding area. Detailed Implementation

[0021] To facilitate understanding of this utility model, a more comprehensive description of this utility model will be provided below, along with embodiments of this utility model, but this does not limit the scope of this utility model.

[0022] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0024] like Figure 1 As shown, a conventional battery cell specifically includes a first electrode (e.g., a positive electrode), a second electrode (e.g., a negative electrode), and a separator. The first and second electrodes have opposite polarities, and the separator is located between the first and second electrodes. The battery cell is formed by stacking and winding the first electrode, separator, and second electrode to form a core. Correspondingly, the first electrode has a first tab 14, and the second electrode has a second tab 34. This type of wound battery cell has high production efficiency and high yield; the battery cell can be formed simply by placing the core in an aluminum-plastic film with square perforations. When the core is placed in the square perforations of the aluminum-plastic film, there are huge gaps between the core and the square outer shell. These gaps cannot accommodate active materials, wasting the space capacity and limiting further improvement in the energy density of the battery cell. The conventional approach of directly pressing a large core into a square shape leads to stress concentration, easily damaging the electrode, and is difficult to implement.

[0025] A type of battery cell assembly, such as Figures 2 to 29As shown, the battery cell assembly includes several core units, each with a rectangular cross-section. Multiple core units are stacked and hot-pressed to form a battery cell assembly. Each core unit includes at least two cores, each core comprising a first electrode 1, a separator 2, and a second electrode 3 wound sequentially. The width of the first tab corresponding to the first electrode is R1, and the width of the second tab corresponding to the second electrode is R2. To facilitate subsequent packaging, tabs with the same polarity are connected in parallel using methods such as ultrasonic welding, laser welding, and pressure welding. This parallel connection effectively creates a parallel structure among the multiple cores. If one core fails partially, the entire battery will not instantly fail, resulting in higher system reliability.

[0026] like Figures 2 to 7 As shown, in some embodiments, the core thickness is H1, the width is L1, and the outermost layer of the core is a diaphragm. The first electrode 1 includes a first double-sided fabric area 11, a first single-sided fabric area 12, a second double-sided fabric area 13, and a first electrode tab 14.

[0027] The second electrode 2 includes a second electrode foil area 21, a second electrode single fabric area 22, a second electrode double fabric area 23, and a second electrode tab 24.

[0028] The adjacent first and second electrodes are separated by a diaphragm to avoid short circuits and complete the winding. The diaphragm length is equal to twice the sum of the width L1 of the first core and the thickness H1 of the first core, that is, the diaphragm length = 2(L1 + H1).

[0029] In some embodiments, the core unit includes a first core and a second core nested and welded together. The first core includes a first electrode 1, a second electrode 3, and a diaphragm 2. The second core includes a third electrode 4, a fifth electrode 5, and a core diaphragm 6. Figure 3 This is a schematic diagram of the structure of the first electrode 1 within the first core. The penultimate fold and half of the second-to-last fold (near the penultimate fold) of the first electrode 1 constitute the second double-sided fabric area 13. The outer layer of this area is the positive electrode coating X. In subsequent core nesting, it forms a bonding surface with the second core through the separator 2. The remaining half of the second-to-last fold of the first electrode 1 constitutes the first single-sided fabric area 12. The outer layer of this area is foil. In subsequent core nesting, it does not form a bonding surface with the second core. This single-sided fabric area design not only saves raw materials to avoid waste but also reduces the cell volume, thereby improving space utilization. The remaining portion of the first electrode is the first double-sided fabric area 11. Figure 3 The first electrode tab 14 shown is welded to the first double-sided fabric area 11 of the first electrode sheet. The position of the first electrode tab 14 can be adjusted according to requirements. The length ratio of the single-sided fabric area 12 of the first electrode sheet to the second double-sided fabric area 13 of the first electrode sheet is 1:3.

[0030] Figure 4This is a structural diagram of the second electrode sheet 3 within the first roll core. The first fold of the second electrode sheet 3 is the second electrode sheet foil area 31; the second and third folds are the second electrode sheet single-fabric area 32; and the remaining portions of the second electrode sheet are the second electrode sheet double-fabric area 33. Figure 4 The second electrode tab 34 shown is welded to the double-sided fabric area 33 of the second electrode sheet. The position of the second electrode tab 34 can be adjusted according to requirements. The length ratio of the foil area 31 of the second electrode sheet to the single-sided fabric area 32 of the second electrode sheet is 1:2.

[0031] Figure 5 This is a schematic diagram of the second core structure. The second core has a thickness of H2 and a width of L2. The outermost layer of the second core is the core diaphragm 6.

[0032] The third electrode 4 includes a third electrode double-fabric area 41 and a third electrode tab 42; the fourth electrode 5 includes a fourth electrode foil area 51, a fourth electrode first single-fabric area 52, a fourth electrode first double-fabric area 53, a fourth electrode second single-fabric area 54, a fourth electrode second double-fabric area 55, and a fourth electrode tab 56. Figure 6 This is a schematic diagram of the structure of the third electrode 4 in the second core, wherein the third electrode tab 42 is welded to the double-sided fabric area of ​​the third electrode 4, and the position of the third electrode tab 42 can be adjusted according to the requirements.

[0033] Figure 7 This is a structural diagram of the fourth electrode 5 within the second core. The first fold of the fourth electrode 5 is the fourth electrode foil area 51; the second and third folds of the fourth electrode 5 are the first single-face material area 52; the penultimate fold and half of the penultimate fold (near the penultimate fold) of the fourth electrode 5 are the second double-face material area 54, the outer layer of which is the negative electrode coating Y. In subsequent core nesting, it forms a bonding surface with the first core through a separator; the remaining half of the penultimate fold of the fourth electrode 5 is the second single-face material area 55, the outer layer of which is foil. In subsequent core nesting, it will not form a bonding surface with the first core. Designing this single-face material area not only saves raw materials to avoid waste but also reduces the cell volume, thereby improving space utilization; the remaining fourth electrode portion is the first double-face material area 53; the fourth electrode tab 56 is soldered to the first double-face material area 53, and its position can be adjusted according to requirements. The length ratio of the fourth electrode foil area 51 to the first single-fabric area 52 of the fourth electrode is 1:2, and the length ratio of the second single-fabric area 55 of the fourth electrode to the second double-fabric area 54 of the fourth electrode is 1:3.

[0034] like Figures 8 to 13As shown, in some embodiments, the core unit includes a first core and a second core, both of which are U-shaped and have a thickness h ≤ 3.5 mm. If the core is too thick, it will be difficult to form an approximate rectangle at the two arm ends when it is pressed into a U-shape, and the ends will still have a large arc. After nesting, new gaps will be formed in the assembly, making it impossible to fully utilize the square space to improve energy density.

[0035] To facilitate clear viewing of the attached drawings, when the main structure is shown, the specific number of winding layers is not displayed. The structure of the first core consists of a first arm 15, a first connecting segment 16, and a second arm 17 connected vertically in sequence. The first electrode lug is on the second arm 17, and the second electrode lug is on the first arm 15. The length of the first arm is A1, and the thickness is B1; the length of the first connecting segment 16 is A2, and the thickness is B2; the length of the second arm is A3, and the thickness is B3. Where A2 = B3. The structure of the second core consists of a third arm 43, a second connecting segment 44, and a fourth arm 45 connected vertically in sequence. The third electrode lug is on the fourth arm 45, and the fourth electrode lug is on the third arm 43. The length of the third arm 43 is A4, and the thickness is B4; the length of the second connecting segment 44 is A5, and the thickness is B5; the length of the fourth arm 45 is A6, and the thickness is B6. Where B2 = B4, B5 = B1, B6 = A5, and A6 = A3 = A2 + A4 = A5 + A1. The first and second cores are nested together with their openings facing each other to form an approximately rectangular assembly. When nesting, the arms of the two cores should be as parallel as possible, with the first arm of the first core inserted into the gap between the third and fourth arms of the second core, and the third arm of the second core inserted into the gap between the first and second arms of the first core.

[0036] The specific method is as follows: Set the hot pressing and shaping process parameters: Temperature: 80℃ ~ 120℃. The hot pressing temperature should be higher than the glass transition temperature of the diaphragm (such as PE / PP) but much lower than its melting point in order to achieve plastic deformation without melting.

[0037] Pressure: 0.5 MPa ~ 3 MPa. The pressure should be sufficient to deform the core but not enough to damage the active material.

[0038] Time: The pressure holding time is 10s ~ 300s.

[0039] Mold material: Use smooth metal molds or molds covered with flexible pads (such as silicone) to reduce damage to the core surface.

[0040] The first core on the left side of the first electrode sheet second double-sided fabric area starting winding position of the first core is bent 90° counterclockwise, and the first core on the right side is pre-compressed to form the first arm; then the first core after the bending point of the first electrode sheet second double-sided fabric area is bent downward by B2 distances counterclockwise is bent 90°, and this part of the first core is pre-compressed to form the second arm, and the remaining part of the first core is pre-compressed to form the first connecting section 16.

[0041] The second core on the right side of the second single fabric area of ​​the fourth pole sheet of the second core is bent 90° clockwise. This part of the second core is pre-compressed to form the third arm. Then, the second core after the bending point of the second double fabric area of ​​the fourth pole sheet of the second core is moved B5 distance to the left is bent 90° counterclockwise. This part of the second core is pre-compressed to form the fourth arm. The remaining part of the second core is pre-compressed to form the second connecting section 44.

[0042] In some embodiments, if the outermost layer of the cell is not a separator, when the first and second cores are nested, an additional separator sheet needs to be inserted between them. This separator sheet must at least cover the mating surfaces of the first and second cores, completely separating the contact between the second double-sided fabric area of ​​the first electrode sheet of the first core and the second double-sided fabric area of ​​the second electrode sheet of the second core. This prevents short circuits between electrodes of different polarities from contacting each other and ensures that the mating surfaces of both the first and second cores can utilize their capacity. The nesting arrangement should ensure that the mating surfaces between the unit cores fully utilize their capacity; that is, the nesting principle is that the positive electrode coating X on the outer layer of the second double-sided fabric area of ​​the first electrode sheet of the first core and the negative electrode coating Y on the outer layer of the second double-sided fabric area of ​​the fourth electrode sheet of the second core form a mating surface completely separated by a separator.

[0043] like Figures 14 to 19 As shown, after the first and second cores are nested, the thickness of the nested assembly is H3 and the length is L3, where L3=A6=A3 and H3=B1+B3+B4+B6. The outermost layer of the nested assembly is a separator. To fully utilize the docking area between the first and second cores and improve battery capacity, the outer layer of the second double-sided fabric area 13 of the first electrode sheet of the first core and the outer layer of the second double-sided fabric area 54 of the fourth electrode sheet of the second core are designed to form a bonding surface through the separator, as shown. Figure 18 As shown, multiple winding units are stacked and arranged to form a battery cell assembly.

[0044] To fully utilize the bonding surfaces between each core unit and increase battery capacity, positive and negative electrode coatings are added to the bonding surfaces between two adjacent core units in a cell assembly, and the positive and negative electrode coatings are separated by a separator.

[0045] When multiple core units are stacked, in order to improve battery capacity, the joint surfaces between the cores are fully utilized, such as... Figures 15 to 17As shown, depending on the actual stacking arrangement, the inner layer of the separator located in the first and second cores is coated with either a positive or negative electrode coating. The separator can be located at the top, bottom, or middle. Figure 19 As shown, multiple winding units are stacked and arranged to form a battery cell assembly.

[0046] like Figure 20 and Figure 21 As shown, in some embodiments, the core unit includes two first cores and one second core, and the second core has an axisymmetric structure, meaning the two arms are of equal length. Furthermore, the bonding surface between the two first cores has no positive electrode coating, and the outermost positive electrode coating of the first core and the outermost negative electrode coating of the second core form a bonding surface separated by a separator. Figure 21 As shown, multiple winding units are stacked and arranged to form a battery cell assembly.

[0047] like Figures 22 to 27 As shown, in some embodiments, the core unit includes a first core and a second core, and both cores are L-shaped. The outermost layer of the first core and the second core is a diaphragm after they are nested together. The outermost positive electrode coating of the first core and the outermost negative electrode coating of the second core form a bonding surface through the diaphragm.

[0048] like Figure 23 As shown, multiple winding units are stacked and arranged to form a battery cell assembly.

[0049] To fully utilize the bonding surfaces between individual cell units and increase battery capacity, a positive or negative electrode coating can be added to the bonding surfaces of each cell unit, depending on the actual situation. The positive and negative electrode coatings are separated by a separator. For example... Figure 27 As shown, multiple winding units are stacked and arranged to form a battery cell assembly.

[0050] For ease of understanding, in all the figures of this application, the positive electrode coating is X, the negative electrode coating is Y, and the core unit is S.

[0051] A battery includes a housing 7 and the cell assembly encapsulated therein.

[0052] The housing 7 is an aluminum-plastic film, which encapsulates the battery cell assembly inside a square aluminum-plastic film housing.

[0053] like Figure 28 and Figure 29 As shown, all the tabs of the winding cores are connected in parallel. In one embodiment, The core units are stacked and arranged in a certain way. First, the soft electrode tab 8 is bent and pre-welded to form the soft electrode tab bundle 9, and then the soft electrode tab bundle 9 is welded to the hard electrode tab 10.

[0054] In another embodiment, the core is stacked and arranged in a certain way, so that the hard tabs are not used for parallel connection of the tabs. The soft tabs are directly bent and welded to form the soft tab welding area 101.

[0055] Experimental data I. Experimental Group: Two cores, each 2.0 mm thick and 80 mm wide, are placed in a U-shaped mold and hot-pressed for 8 seconds at 100°C and 2.5 MPa to form a U-shape. An 82 mm wide insulating diaphragm is inserted between the two U-shaped cores, and then they are nested with their openings facing each other. Finally, all the positive tabs are welded in parallel using an ultrasonic welder. After encapsulation, baking, and electrolyte injection, a battery cell is formed with a thickness of 8 mm, a width of 42 mm, and a length of 59 mm.

[0056] II: Control Group A core with a thickness of 8mm, a width of 42mm, and a length of 59mm is taken, and after being hot-pressed and shaped, it is formed into a battery cell through processes such as encapsulation, baking, and liquid injection.

[0057]

[0058] The experimental data shows that the experimental group weighed more than the control group, indicating that the experimental group contained more active substances in the same space, and its volume was increased by 2.68% under the premise of the same injection volume as the control group.

[0059] In summary, the structure of this application results in extremely high space utilization and improved energy density of the battery: Through the ingenious "U-shaped nesting" design, the final composite cell perfectly fills the four corners of the square casing, virtually eliminating all ineffective gaps and maximizing the use of packaging space, thereby significantly improving the volumetric energy density of the cell. The structure of this application is superior, with lower internal stress: it employs a method of pre-pressing and then combining multiple small cores separately. Small cores are more easily deformed, and the resulting internal stress and electrode damage risk are far less than directly pressing large cores, better ensuring the cycle life and safety of the cell. The multiple cores essentially constitute a parallel structure. If one core fails partially, it will not cause the entire battery to fail instantly, resulting in higher system reliability. Improved rate charge / discharge performance and thermal management performance: Due to the use of multi-tab parallel connection, the internal resistance of the entire cell is significantly reduced, which is beneficial to improving the battery's rate charge / discharge performance and thermal management performance.

[0060] It should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A battery cell assembly, characterized in that: The battery includes a core unit with a rectangular cross-section. Each core unit includes at least two cores, each core comprising a first electrode, a diaphragm, and a second electrode wound sequentially. The widths of the first tabs corresponding to the first electrode are all the same, and the widths of the second tabs corresponding to the second electrode are all the same. Tabs with the same polarity are connected in parallel. The number of core units can be one or more. When the number of core units is multiple, the multiple core units are stacked and hot-pressed to form a battery cell assembly.

2. A cell assembly according to claim 1, characterized in that: The core unit includes a first core and a second core. The first core includes a first electrode sheet, a diaphragm, and a second electrode sheet. The first electrode sheet includes a first double-sided fabric area, a first single-sided fabric area, and a first double-sided fabric area, which are sequentially wound. A first electrode tab is welded to the first double-sided fabric area. The second electrode sheet includes a second electrode foil area, a second single-sided fabric area, and a second double-sided fabric area, which are sequentially wound. A second electrode tab is welded to the second double-sided fabric area. The second core includes a third electrode sheet, a core diaphragm, and a fourth electrode sheet. The third electrode sheet includes a third electrode sheet double-sided fabric area and a third electrode tab welded thereon. The fourth electrode sheet includes a fourth electrode sheet foil area, a fourth electrode sheet first single-sided fabric area, a fourth electrode sheet first double-sided fabric area, and a fourth electrode sheet second double-sided fabric area, which are sequentially wound together. The fourth electrode tab is welded to the first double-sided fabric area of ​​the fourth electrode sheet.

3. A cell assembly according to claim 2, characterized in that: The core unit includes a first core and a second core that are nested together to form a rectangle after hot pressing. Both the first core and the second core are U-shaped structures after hot pressing. After hot pressing, the single-fabric area of ​​the first electrode will not form a joint surface with the second core, while the second double-fabric area of ​​the first electrode will form a joint surface with the second core, and the two are separated by a diaphragm. The second single-fabric area of ​​the fourth electrode will not form a joint surface with the first core, while the second double-fabric area of ​​the fourth electrode will form a joint surface with the first core, and the two are separated by a diaphragm.

4. A cell assembly according to claim 3, characterized in that: The structure of the first core consists of a first arm, a first connecting segment, and a second arm connected vertically in sequence. The first electrode tab is on the second arm, and the second electrode tab is on the first arm. The length of the first arm is A1, and the thickness is B1. The length of the first connecting segment is A2, and the thickness is B2. The length of the second arm is A3, and the thickness is B3, where A2 = B3.

5. A cell assembly according to claim 3, characterized in that: The structure of the second core consists of a third arm, a second connecting segment, and a fourth arm connected vertically in sequence. The third electrode lug is on the fourth arm, and the fourth electrode lug is on the third arm. The length of the third arm is A4, and the thickness is B4. The length of the second connecting segment is A5, and the thickness is B5. The length of the fourth arm is A6, and the thickness is B6. Wherein, B2=B4, B5=B1, B6=A5, and A6=A3=A2+A4=A5+A1.

6. A cell assembly according to claim 3, characterized in that: A positive or negative electrode coating is added to the bonding surface between two adjacent core units, and the positive and negative electrode coatings are separated by a diaphragm.

7. A cell assembly according to claim 3, characterized in that: The core unit includes two first cores and one second core. Both the first core and the second core are U-shaped structures. The two arms of the first core are not equal in length, while the two arms of the second core are equal in length. The second core is located in the middle. There is no positive electrode coating on the joint surface between the two first cores. The outermost positive electrode coating of the first core and the outermost negative electrode coating of the second core are separated by a diaphragm to form a joint surface.

8. A cell assembly according to claim 3, characterized in that: The core unit includes a first core and a second core, both of which are L-shaped. The outermost layer of the first core and the second core is a diaphragm after they are nested together. The outermost positive electrode coating of the first core and the outermost negative electrode coating of the second core form a bonding surface through the diaphragm.

9. A cell assembly according to claim 1, characterized in that: After the core units are stacked and arranged in a set order, the tabs of the same polarity are welded together to form a tab welding area.

10. A cell assembly according to claim 9, characterized in that: Multiple soft tabs of the same polarity are welded together to form a soft tab bundle, and a hard tab is welded onto the soft tab bundle.

11. A battery comprising the cell assembly according to any one of claims 1-10, characterized in that: The battery cell assembly includes a rectangular housing and the cell assembly encapsulated within it.

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