Secondary battery monomer roll core structure, secondary battery monomer and energy storage device

Abstract

The utility model relates to the technical field of batteries, and discloses a secondary battery monomer roll core structure, a secondary battery monomer and an energy storage device. The secondary battery monomer roll core structure comprises two or more roll windings which are bundled and fixed; the winding groups are formed by winding materials, and each winding group comprises two winding cores; the material comprises an isolating membrane, a negative pole piece and a positive pole piece in the stacking direction, the material comprises two winding areas and a pole piece interruption area arranged between the two winding areas in the length direction, and the negative pole piece and the positive pole piece are both disconnected in the pole piece interruption area; the two winding cores are respectively formed by winding two winding areas towards a pole piece interruption area, the two winding cores are connected into a whole through an isolating membrane of the pole piece interruption area, the two winding cores of the winding groups are arranged in parallel along a first direction, and the adjacent winding groups are arranged in parallel along a second direction. According to the utility model, at least one of the technical problems of easy wrinkling, non-uniform tension control and poor heat dissipation during winding of the pole piece can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a secondary battery monomer winding core structure, a secondary battery monomer and an energy storage device. Background Art

[0002] Due to the advantages of lithium-ion batteries such as good rate performance, high safety, large capacity, long cycle life, and green environmental protection, they are widely used in many fields such as 3C digital products, power vehicles, and energy storage power stations. With the challenges brought by global climate and energy issues, the demand for electricity in emerging industries has gradually increased, energy storage has gradually penetrated into more scenarios, and long-term energy storage has also received widespread attention.

[0003] Existing large-size batteries are generally made by merging multiple single-wound cores internally, which can increase battery capacity but also has the following technical problems:

[0004] 1. The length of the winding pole piece becomes longer, which is prone to wrinkling and poor tension control;

[0005] 2. Through simple stacking, the battery cells expand greatly, and the uneven stress distribution will affect the cycle life;

[0006] 3. Poor internal heat dissipation will cause heat accumulation and cause safety risks. Utility Model Content

[0007] In view of this, the utility model provides a secondary battery cell winding core structure, a secondary battery cell and an energy storage device to solve at least one of the technical problems of easy wrinkling of pole piece winding, uneven tension control and poor heat dissipation.

[0008] In the first aspect, the utility model provides a secondary battery cell core structure, comprising at least two winding groups; the winding groups are formed by winding materials, and each winding group comprises two cores; the material comprises an isolation membrane, a negative electrode sheet and a positive electrode sheet along the stacking direction, and the material comprises two winding areas and a sheet interruption area arranged between the two winding areas along the length direction, and the negative electrode sheet and the positive electrode sheet are both disconnected in the sheet interruption area; the two cores are respectively formed by winding the two winding areas toward the sheet interruption area, and the two cores are connected as a whole through the isolation membrane in the sheet interruption area, the two cores of the winding group are arranged side by side along the first direction, and the adjacent winding groups are arranged side by side along the second direction.

[0009] Beneficial effects:

[0010] 1. The winding group is wound in both directions to form an integrated double core, and the arrangement direction of the core of one winding group is different from that of the adjacent winding group, which can reduce the stacking thickness, significantly improve the rate, heat dissipation and wetting characteristics, and improve the process production efficiency;

[0011] 2. Due to the bidirectional winding, two winding cores can be wound at the same time, which can improve the winding efficiency;

[0012] 3. The use of bidirectional winding to form a double core can improve the problems of wrinkles and uneven tension control of a single large core to a certain extent, and improve the contact consistency between the pole pieces.

[0013] 4. Compared with the current technical solution of stacking four winding cores along the thickness direction, the utility model reduces the stacking thickness, which can reduce the heat accumulation in the thickness direction, avoid uneven distribution of electrolyte, and improve electrical performance and safety performance.

[0014] 5. The negative electrode and positive electrode of the material are cut and glued in turn in the interruption area of ​​the electrode. There is no double-sided empty foil area or other functional coating area at the end, which can reduce the use of inactive electrode areas and improve energy density. By eliminating the empty foil connection, the problem of serious short circuit failure caused by puncture of the empty foil during the needle puncture process can also be avoided, thereby improving safety performance.

[0015] In an optional embodiment, the two cores are arranged side by side along their width direction, and adjacent winding groups are stacked along the thickness direction of the core; or, the two cores are bent through the pole piece interruption area and stacked along their thickness direction, and adjacent winding groups are arranged side by side along the width direction of the core.

[0016] In an optional embodiment, a bracket is provided between adjacent winding groups, and the bracket is provided with a limiting groove, and the groove wall of the limiting groove is suitable for abutting against at least part of the outer peripheral surface of the winding core.

[0017] In an optional embodiment, the groove surface of the limiting groove is an arc surface that matches the arc surface of the winding core.

[0018] In an optional embodiment, at least two limiting grooves are provided, and the area enclosed by the back sides of the groove surfaces of adjacent limiting grooves is a hollow structure.

[0019] In an optional embodiment, the bracket is provided with a plurality of through holes at intervals.

[0020] In an optional embodiment, a filler is provided in the through hole, and the filler includes a lithium supplement material and / or an alkaline material.

[0021] In an optional embodiment, an insulating layer is provided on the surface of the bracket.

[0022] In the second aspect, the utility model also provides a secondary battery cell, including a shell, a secondary battery cell winding core structure of any one of the above technical solutions, and a cover plate assembly. The shell includes a housing cavity with an open end, and the secondary battery cell winding core structure is arranged in the housing cavity of the shell; the top of each winding core of the secondary battery cell winding core structure is provided with a positive electrode ear, and the bottom of the winding core is provided with a negative electrode ear, and the negative electrode ear is electrically connected to the shell; the cover plate assembly is arranged at the open end of the shell, and the secondary battery cell winding core structure is encapsulated in the shell; the cover plate assembly is provided with a positive electrode column, and the positive electrode column is electrically connected to the positive electrode ear.

[0023] Beneficial effects: Since the secondary battery cell includes the secondary battery cell winding core structure, it has the same effects as the secondary battery cell winding core structure, which will not be described in detail herein.

[0024] In a third aspect, the utility model further provides an energy storage device, comprising the secondary battery cell in the above technical solution.

[0025] Beneficial effects: Since the energy storage device includes a secondary battery cell, it has the same effects as the secondary battery cell, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of a secondary battery cell winding core structure according to an embodiment of the utility model;

[0028] Figure 2 A schematic diagram of another secondary battery cell winding core structure according to an embodiment of the utility model;

[0029] Figure 3 The schematic diagram of material arrangement;

[0030] Figure 4 is a structural schematic diagram of a bracket;

[0031] Figure 5 for Figure 4 A top view of the bracket shown;

[0032] Figure 6 is a schematic diagram of a partial structure of another stent;

[0033] Figure 7This is a schematic diagram of the exploded structure of the cover plate, the insulating plate and the bracket in the secondary battery cell of the embodiment of the utility model;

[0034] Figure 8 This is a schematic structural diagram of a secondary battery cell winding core structure connected to a positive electrode tab according to an embodiment of the utility model;

[0035] Fig. 9 It is a structural schematic diagram of a secondary battery cell winding core structure connected to a negative electrode ear according to an embodiment of the utility model.

[0036] Description of reference numerals:

[0037] 1. Winding group; 101. Winding core; 2. Material; 201. Isolation film; 202. Negative electrode sheet; 203. Positive electrode sheet; 204. Winding area; 205. Interruption area in the electrode sheet; 3. Bracket; 301. Limiting groove; 302. Through hole; 303. Filler; 4. Positive electrode ear; 5. Negative electrode ear; 6. Cover plate; 7. Insulating plate; 8. Positive electrode column; 9. Tape. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0039] Affected by the process and heat dissipation, the wound large battery cells are prone to wrinkling and have a low quality rate. The stacking process is inefficient, and with the increase in volume, problems such as liquid retention, infiltration, heat dissipation, and expansion appear. There are certain bottlenecks in increasing the capacity of a single battery cell. The secondary battery cell winding core structure, secondary battery cell, and energy storage device provided by the utility model aim to solve the above technical problems one by one.

[0040] Combine the following Figures 1 to 9 , describing an embodiment of the utility model.

[0041] According to an embodiment of the utility model, on the one hand, a secondary battery cell core structure is provided, comprising at least two winding groups 1; the winding group 1 is formed by winding a material 2, and each winding group 1 comprises two cores 101; the material 2 comprises an isolation film 201, a negative electrode sheet 202 and a positive electrode sheet 203 along the stacking direction, and the material 2 comprises two winding areas 204 and a sheet interruption area 205 arranged between the two winding areas 204 along the length direction, and the negative electrode sheet 202 and the positive electrode sheet 203 are both disconnected in the sheet interruption area 205; the two cores 101 are respectively formed by winding the two winding areas 204 toward the sheet interruption area 205, and the two cores 101 are connected as a whole through the isolation film 201 of the sheet interruption area 205, and the two cores 101 of the winding group 1 are arranged in parallel along the first direction, and the adjacent winding groups 1 are arranged in parallel along the second direction.

[0042] Specifically, the parallel arrangement direction of the two winding cores 101 of the winding group 1 is different from the parallel arrangement direction of the adjacent winding group 1, that is, the winding core 101 and the winding group 1 are arranged in two directions, so that the thickness of the secondary battery cell winding core structure can be dispersed. In some embodiments, the first direction can be along the thickness direction of the winding core 101, such as Figure 2 As shown in the Y direction, the second direction may be along the width direction of the winding core 101, such as Figure 2 The X direction is shown.

[0043] The winding group 1 of the utility model is wound by a material 2, and the material 2 is provided with two winding areas 204 and a pole piece interruption area 205 located in the middle, and the two winding areas 204 can be wound from the two ends of the material 2 to the pole piece interruption area 205, thereby obtaining two winding cores 101. Since the pole piece interruption area 205 of the material 2 is only interrupted by the positive pole piece 203 and the negative pole piece 202, the isolation film 201 is still in a connected state, and therefore, the two winding cores 101 of a winding group 1 are connected as a whole through the isolation film 201.

[0044] The utility model has the following beneficial effects:

[0045] 1. The winding group 1 is wound in both directions to form two integrated winding cores 101, and the arrangement direction of the winding core 101 of one winding group 1 is different from that of the adjacent winding group 1, which can reduce the stacking thickness, significantly improve the magnification, heat dissipation and wetting characteristics, and improve the process production efficiency;

[0046] 2. Due to the bidirectional winding, the winding of two winding cores 101 can be completed at the same time, which can improve the winding efficiency;

[0047] 3. The two winding cores 101 are formed by bidirectional winding, which can improve the wrinkles and uneven tension control of a single large winding core 101 to a certain extent and improve the contact consistency between the pole pieces.

[0048] 4. Compared with the current technical solution of stacking four winding cores 101 along the thickness direction, the present invention reduces the stacking thickness, thereby reducing heat accumulation in the thickness direction, avoiding uneven distribution of electrolyte, and improving electrical performance and safety performance.

[0049] 5. The negative electrode sheet 202 and the positive electrode sheet 203 of the material 2 are cut and glued in turn in the electrode sheet interruption area 205, and there is no double-sided empty foil area or other functional coating area at the end, which can reduce the use of inactive electrode areas and improve energy density. By eliminating the empty foil connection, the problem of serious short circuit failure caused by puncture of the empty foil during the needle puncture process can also be avoided, thereby improving safety performance.

[0050] In one embodiment, Figure 1 As shown, two winding cores 101 are arranged side by side along the width direction thereof, and adjacent winding groups 1 are stacked along the thickness direction of the winding cores 101. The two winding cores 101 located at the top are one winding group 1, and the two winding cores 101 located at the bottom are another winding group 1.

[0051] Specifically, in some embodiments, the end surface of the winding core 101 is approximately elliptical, and the width direction of the winding core 101 refers to the direction in which the major axis of the ellipse extends. Figure 2 The thickness direction of the core 101 refers to the direction in which the minor axis of the ellipse extends. Figure 2 It is represented by the direction shown by Y.

[0052] In one embodiment, Figure 2 As shown, two winding cores 101 are bent through the pole piece interruption area 205 and stacked along the thickness direction thereof, and adjacent winding groups 1 are arranged side by side along the width direction of the winding core 101 .

[0053] The above two arrangements can both achieve the above effects.

[0054] In one embodiment, a bracket 3 is provided between adjacent winding groups 1 , and the bracket 3 is provided with a limiting groove 301 , and a groove wall of the limiting groove 301 is suitable for abutting against at least a portion of the outer circumference of the winding core 101 .

[0055] By placing the bracket 3 between adjacent winding groups 1, the limiting groove 301 of the bracket 3 can abut against the outer peripheral surface of the core 101, which can improve the problem of poor consistency of the electrode interface contact in the arc area at the corner of the core 101. The bracket 3 can exert certain constraints during the expansion process in the later stage of the cycle to avoid local failure of the arc area and cause degradation of the battery cell performance.

[0056] In some embodiments, one battery includes four winding cores 101 , and accordingly, the bracket 3 includes four limiting grooves 301 .

[0057] Specifically, the bracket 3 can be a separate structure. Of course, in order to improve the structural stability, the bracket 3 can also be integrated on the cover assembly. Specifically, the bracket 3 and the insulating plate 7 in the cover assembly are integrated into one.

[0058] In one embodiment, the groove surface of the limiting groove 301 is an arc surface adapted to the arc surface of the winding core 101 .

[0059] Since the corner of the winding core 101 is an arc surface, the groove surface of the limiting groove 301 is set to be an arc surface to adapt thereto, thereby further improving the problem of poor contact consistency of the pole piece interface in the arc area at the corner of the winding core 101 .

[0060] In one embodiment, at least two limiting grooves 301 are provided, and the area enclosed by the back sides of the groove surfaces of adjacent limiting grooves 301 is a hollow structure.

[0061] Specifically, in one embodiment, the bracket 3 is provided with four limiting grooves 301, and the back sides of the groove surfaces of the four adjacent limiting grooves 301 form a diamond-shaped area, which is set as a hollow structure, which can reserve enough space to accommodate the electrolyte and also play a role in weight reduction.

[0062] In one embodiment, the bracket 3 is provided with a plurality of through holes 302 at intervals.

[0063] A plurality of through holes 302 are provided on the bracket 3, that is, the bracket 3 is made into a porous structure, which is convenient for the migration of electrolyte solvent molecules and ions. The material of the bracket 3 can be one of porous polyurethane, polyimide resin, rubber, mica sheet, asbestos, ceramic, and ion sieve, and its function is to be close to the arc area, impose certain stress constraints on the arc area, make the pole piece contact in this area more uniform, inhibit disordered expansion in the later stage of the cycle, and improve the battery performance.

[0064] In one embodiment, a filler 303 is disposed in the through hole 302 , and the filler 303 includes a lithium supplement material and / or an alkaline material.

[0065] By setting the filler 303 in the through hole 302, the filler 303 can be a lithium supplement material, so that it can be used as a lithium source to supplement the battery cycle life during the cycle. The inside of the through hole 302 of the bracket 3 can be filled with active lithium supplement material by physical or chemical adsorption, etc. The active lithium supplement is lithium oxide, lithium peroxide, lithium hydroxide, lithium nitride, lithium sulfide, lithium fluoride, etc. When the concentration of electrolyte lithium salt is low in the late cycle, lithium ions or lithium supplement material escape from the porous structure and dissolve in the electrolyte as a supplementary lithium source, thereby improving the battery cell cycle performance.

[0066] The filler 303 may also be other special materials, such as alkaline materials, which can absorb the side reaction products generated during the abnormal process of the battery cell to prevent the continuous decomposition of the active components of the electrode and cause battery failure. Specifically, the alkaline materials include sodium hydroxide, sodium carbonate, sodium bicarbonate, aluminum hydroxide, aluminum oxide, zinc oxide or magnesium oxide, which can achieve the effects of dehydration, deacidification and degassing, and improve the cycle and storage performance of lithium-ion batteries.

[0067] In one embodiment, an insulating layer is provided on the surface of the bracket 3 .

[0068] Specifically, an insulating heat-insulating layer may be coated on the surface of the bracket 3 . The insulating heat-insulating layer is made of insulating heat-insulating materials, including but not limited to ceramics. By providing the insulating heat-insulating layer on the surface of the bracket 3 , safety and stability can be improved.

[0069] In one embodiment, the two ends of the material 2 are the starting ends of the winding area 204, and the end close to the pole piece interruption area 205 is the ending end. In the two winding areas 204, the ending end of the positive pole piece 203 is a single-sided structure, and the rest are double-sided structures. The starting end of the negative pole piece 202 is a single-sided structure, and the rest are double-sided structures.

[0070] Specifically, the two winding groups can be attached and fixed by using adhesive tape 9 to fix the two winding groups.

[0071] In one embodiment, adjacent winding groups 1 can be adhered and fixed as one with adhesive tape 9 .

[0072] According to an embodiment of the utility model, in the second aspect, a secondary battery cell is also provided, comprising a shell, a secondary battery cell winding core structure of any one of the above technical solutions, and a cover plate assembly. The shell comprises a receiving cavity with an open end, and the secondary battery cell winding core structure is arranged in the receiving cavity of the shell; each winding core 101 of the secondary battery cell winding core structure is provided with a positive pole ear 4 at the top, and a negative pole ear 5 at the bottom of the winding core 101, and the negative pole ear 5 is electrically connected to the shell; the cover plate assembly is arranged at the open end of the shell, and the secondary battery cell winding core structure is encapsulated in the shell; the cover plate assembly is provided with a positive pole column 8, and the positive pole column 8 is electrically connected to the positive pole ear 4.

[0073] Because the secondary battery cell includes the secondary battery cell winding core structure, it has the same effect as the secondary battery cell winding core structure, and will not be described in detail here.

[0074] Specifically, the positive electrode ears 4 are welded in pairs through adapters to form a whole and are connected to a pole.

[0075] In this embodiment, two winding groups 1 are included. Since each winding group 1 includes two winding cores 101, a secondary battery cell winding core structure includes four winding cores 101. Along the thickness direction of the secondary battery cell structure, two adjacent positive electrode ears 4 are electrically connected in pairs, and then connected to the pole of the cover plate assembly.

[0076] Specifically, the cover plate assembly includes a cover plate 6 body and an insulating plate 7. The cover plate assembly is provided with two poles. The positive pole ears 4 are connected in pairs through a switching plate and then pass through the insulating plate 7 to be electrically connected to the poles at corresponding positions.

[0077] The scheme of providing two positive poles 8 and negatively charging the shell can increase the current density and uniformity and improve the rate performance.

[0078] According to an embodiment of the present utility model, in a third aspect, an energy storage device is also provided, comprising the secondary battery cell in the above technical solution.

[0079] Since the energy storage device includes a secondary battery cell and has the same effect as the secondary battery cell, it will not be described in detail here.

[0080] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A secondary battery cell winding core structure, characterized in that: It comprises at least two winding groups (1), wherein the winding groups (1) are arranged in parallel or in a stacked manner; The winding group (1) is formed by winding a material (2), and each of the winding groups (1) comprises two winding cores (101); The material (2) comprises a separator (201), a negative electrode sheet (202) and a positive electrode sheet (203) along the stacking direction; the material (2) comprises two winding regions (204) and a sheet interruption region (205) disposed between the two winding regions (204) along the length direction; the negative electrode sheet (202) and the positive electrode sheet (203) are both disconnected at the sheet interruption region (205); The two winding cores (101) are respectively formed by winding the two winding areas (204) toward the pole piece interruption area (205), and the two winding cores (101) are connected as a whole via the isolation film (201) of the pole piece interruption area (205); The two winding cores (101) of the winding group (1) are arranged in parallel along a first direction, and the adjacent winding groups (1) are arranged in parallel along a second direction.

2. The secondary battery cell winding core structure according to claim 1, characterized in that: The two winding cores (101) are arranged side by side along the width direction thereof, and the adjacent winding groups (1) are stacked along the thickness direction of the winding cores (101); Alternatively, the two winding cores (101) are bent through the pole piece interruption area (205) and stacked along the thickness direction thereof, and the adjacent winding groups (1) are arranged side by side along the width direction of the winding core (101).

3. The secondary battery cell winding core structure according to claim 1 or 2, characterized in that: A bracket (3) is provided between adjacent winding groups (1), and the bracket (3) is provided with a limiting groove (301), and the groove wall of the limiting groove (301) is suitable for abutting against at least part of the outer peripheral surface of the winding core (101).

4. The secondary battery cell winding core structure according to claim 3, characterized in that: The groove surface of the limiting groove (301) is an arc surface adapted to the arc surface of the winding core (101).

5. The secondary battery cell winding core structure according to claim 4, characterized in that: At least two limiting grooves (301) are provided, and the area enclosed by the back sides of the groove surfaces of adjacent limiting grooves (301) is a hollow structure.

6. The secondary battery cell winding core structure according to claim 3, characterized in that: The bracket (3) is provided with a plurality of through holes (302) at intervals.

7. The secondary battery cell winding core structure according to claim 6, characterized in that: A filler (303) is provided in the through hole (302), and the filler (303) includes a lithium supplement material and / or an alkaline material.

8. The secondary battery cell winding core structure according to claim 3, characterized in that: The surface of the bracket (3) is provided with an insulating and heat-insulating layer.

9. A secondary battery cell, characterized in that: include: a housing, the housing comprising a receiving cavity having an open end; The secondary battery cell winding core structure according to any one of claims 1 to 8, wherein the secondary battery cell winding core structure is arranged in the accommodating cavity of the shell; each winding core (101) of the secondary battery cell winding core structure is provided with a positive electrode ear (4) at the top, and a negative electrode ear (5) at the bottom of the winding core (101), and the negative electrode ear (5) is electrically connected to the shell; A cover plate assembly is arranged at the open end of the shell to encapsulate the secondary battery cell core structure in the shell; the cover plate assembly is provided with a positive electrode column (8), and the positive electrode column (8) is electrically connected to the positive electrode ear (4).

10. An energy storage device, characterized in that: The secondary battery cell according to claim 9 is included.

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