Battery cell structure, secondary battery, and electric device

Abstract

The utility model belongs to battery technical field, concretely relates to a kind of electric core structure, secondary battery and electric equipment, wherein, the electric core structure includes first pole piece and second pole piece and is set to the isolation film between the first pole piece and the second pole piece;And the first pole piece, the isolation film and the second pole piece are sequentially wound settings, to form winding body;At least one corner section and at least one horizontal section are equipped on the winding body;Extrusion part and at least one linking part are equipped in the corner section;One end of the extrusion part and / or one end of the linking part is connected to the horizontal section.The utility model can effectively reduce the width of winding body;And improve the security and stability of use.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, and in particular relates to a cell structure, a secondary battery, and an electrical device. Background Technology

[0002] As market demands for longer battery life in mobile phones increase, customers are placing higher demands on the energy density (ED) of battery cells. Currently, battery cells produced using the winding process have semi-circular arc-shaped areas at both ends after winding and hot pressing, and are then packaged.

[0003] However, in this processing method, the top and bottom of the cell are subjected to heat pressing during the hot pressing process, while the sides are not. During subsequent charge-discharge cycles, the electrode plates expand, and the edges are compressed, preventing stress release. To improve the energy density of the cell, existing market anode materials all incorporate silicon (Si). Since Si has a larger coefficient of thermal expansion than conventional graphite, the expansion and compression of the cell corners after cycling causes the outermost aluminum film at the corners to stretch and potentially break. Therefore, it is necessary to increase the electrode spacing at the corners to allow space for Si expansion. Simultaneously, Si is relatively hard, and the micro-discharge caused by powder shedding at the corners is much greater than with graphite. This means that the K-value problem and short-circuit problem of the silicon anode are more significant, affecting the safety and stability of the cell. Utility Model Content

[0004] The purpose of this utility model is to provide a battery cell structure that addresses the shortcomings of existing technologies and solves the technical problem of low safety in the use of existing technologies.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A battery cell structure includes a first electrode and a second electrode, and a separator disposed between the first electrode and the second electrode; the first electrode, the separator, and the second electrode are sequentially wound to form a wound body; the wound body has at least one corner segment and at least one horizontal segment; the corner segment has a compression portion and at least one connecting portion; one end of the compression portion and / or one end of the connecting portion is connected to the horizontal segment.

[0007] Preferably, the connecting portion includes a first arc-shaped segment; one end of the first arc-shaped segment is connected to one end of the horizontal segment; and the other end of the first arc-shaped segment is connected to one end of the extrusion portion.

[0008] Preferably, the extrusion section includes a straight section; the two ends of the straight section are respectively connected to one side of two different first arc-shaped sections.

[0009] Preferably, the central angle corresponding to the first arc segment is α, and α satisfies: 45°≤α≤80°.

[0010] Preferably, the extrusion section includes an arc segment; the two ends of the arc segment are respectively connected to one end of two different first arc segments to form a concentric curve segment;

[0011] The relationship between the arc circumference of the curve segment, D2, and the thickness of the winding body, D1, satisfies: D2 = (1.5 ~ 2) * D1.

[0012] Preferably, the extrusion section includes at least one second arc-shaped segment and at least one straight segment; the second arc-shaped segment and the straight segment are arranged alternately; the second arc-shaped segment is recessed toward the interior of the winding body; and one end of the second arc-shaped segment and / or one end of the straight segment is connected to the first arc-shaped segment.

[0013] Preferably, the extrusion portion includes a protruding section; the connecting portion includes a recessed section; one end of the protruding section is connected to one end of the recessed section; the other end of the recessed section is connected to one of the horizontal sections; and the other end of the protruding section is connected to another horizontal section.

[0014] Preferably, the relationship between the width L0 of the wound body before extrusion, the width L1 of the wound body after extrusion, and the thickness D1 of the wound body before or after extrusion satisfies: L0-L1<D1*40%.

[0015] This utility model also discloses a secondary battery, including the aforementioned cell structure.

[0016] This utility model also discloses an electrical device, including the aforementioned secondary battery.

[0017] The beneficial effects of this utility model are that, by adding a squeezing part to the corner section at the side end, the corner section of the bare cell is squeezed, so that the squeezing part and the connecting part deform toward the inside of the winding body, thereby reducing the arc area of ​​the corner section and effectively reducing the width of the winding body; thus, it can facilitate the stress release of the winding body during the subsequent charging and discharging process and reduce the occurrence of lithium plating; therefore, it can improve the safety and stability of use. Attached Figure Description

[0018] The following will refer to the appendix. Figures 1-8 This section describes the features, advantages, and technical effects of exemplary embodiments of the present invention.

[0019] Figure 1 This is a schematic diagram of the battery cell structure according to an embodiment of the present invention;

[0020] Figure 2 This is a partially enlarged view of the battery cell structure according to an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the extrusion state of the battery cell structure according to an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of the battery cell structure before extrusion according to an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the battery cell structure according to another embodiment of the present invention;

[0024] Figure 6 This is a schematic diagram of the battery cell structure according to another embodiment of the present invention;

[0025] Figure 7 This is a schematic diagram of the battery cell structure according to another embodiment of the present invention;

[0026] Figure 8 This is a schematic diagram of the battery cell structure according to one embodiment of the present invention.

[0027] In the diagram: 100 - separator membrane; 200 - first electrode; 300 - second electrode; 400 - winding body; 401 - horizontal section; 402 - corner section; 410 - extrusion section; 411 - straight section; 412 - raised section; 413 - arc section; 414 - second arc section; 415 - straight section; 420 - connecting section; 421 - first arc section; 422 - recessed section; 403 - first gap; 404 - second gap; 51 - upper pressure plate; 52 - lower pressure plate; 53 - hot-pressing push block. Detailed Implementation

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0029] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0030] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or multiple situations existing alone. In addition, the character " / " in this document generally indicates that the related objects before and after are in an "or" relationship.

[0032] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0033] The following is in conjunction with the appendix Figures 1 to 8 The present invention will be described in further detail, but this is not intended to limit the scope of the present invention.

[0034] like Figure 1 As shown, in one embodiment of this utility model, the battery cell structure includes a first electrode 200 and a second electrode 300, and a separator 100 disposed between the first electrode 200 and the second electrode 300; the first electrode 200, the separator 100, and the second electrode 300 are sequentially wound to form a wound body 400; the wound body 400 is provided with at least one corner segment 402 and at least one horizontal segment 401; the corner segment 402 is provided with a pressing part 410 and at least one connecting part 420; one end of the pressing part 410 and / or one end of the connecting part 420 is connected to the horizontal segment 401.

[0035] The technical solution of this utility model adds a squeezing part to the corner section at the side end to perform a squeezing operation on the corner section of the bare battery cell. This causes the squeezing part and the connecting part to deform towards the inside of the winding body, thereby reducing the arc area of ​​the corner section and effectively reducing the width of the winding body. This, in turn, facilitates stress release of the winding body during subsequent charging and discharging processes, reducing the occurrence of lithium plating. Therefore, it can improve the safety and stability of use.

[0036] In other words, the side extrusion section 410 is hot-pressed to reduce the arc at the corner, that is, the first gap 403 and the second gap 404 between the electrode layers inside the corner area are increased. After the cell expands cyclically, the problem of cathode breakage at the outer corner (this breakage is caused by the expansion and extrusion in the corner area) is solved. At the same time, since many K-value problems are caused by powder shedding due to creases at the corner, this process can alleviate the powder shedding caused by excessive extrusion at the corner.

[0037] Specifically, in some embodiments, the first electrode 200 can be either a positive electrode or a negative electrode; the second electrode 300 can be either a positive electrode or a negative electrode. The positive electrode includes a positive current collector and a positive active material layer, the positive active material layer being coated on the surface of the positive current collector; the material of the positive current collector can be aluminum, and the positive active material layer includes a positive active material, such as lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode includes a negative current collector and a negative active material layer, the negative active material layer being coated on the surface of the negative current collector; the material of the negative current collector can be copper, and the negative active material layer includes a negative active material, such as carbon or silicon. The separator 100 can be made of PP (polypropylene) or PE (polyethylene), etc.

[0038] Specifically, in some implementations, such as Figure 1 and 2 As shown in Figures 7 and 8, the connecting portion 420 includes two outwardly protruding first arc-shaped segments 421; one end of one first arc-shaped segment 421 is connected to one end of one horizontal segment 401; the other end of one first arc-shaped segment 421 is connected to one end of the extrusion portion 410; one end of the other first arc-shaped segment 421 is connected to one end of another horizontal segment 401; and the other end of the other first arc-shaped segment 421 is connected to the other end of the extrusion portion 410. This structure, through the arc-shaped connecting protrusion of the first arc-shaped segment 421, can effectively adjust the deformation direction outward, thereby reducing excessive extrusion deformation of the non-extrusion portion inside the wound body 400, which would affect its normal use; thus improving its safety and stability in use.

[0039] Specifically, in some of its implementations, such as Figure 1 and 2As shown, the extrusion section 410 includes a straight section 411; the two ends of the straight section 411 are respectively connected to one end of two different first arc-shaped sections 421. This structure forms the straight section 411 by hot-pressing the corner section of the winding body 400 through the planar contact surface of the hot-pressing pusher 53; thereby improving the convenience of hot-pressing operation and reducing excessive extrusion deformation of the winding body 400 by non-extrusion parts, which would affect its normal use; thus improving its safety and stability in use. That is, heating the outermost layers of the winding body 400 (45℃~95℃) can release stress in advance and reduce rebound. In some embodiments, such as Figure 2 As shown, when the extrusion section 410 is a straight section 411, the central angle corresponding to the first arc-shaped section 421 is α, and α satisfies: 45°≤α≤80°. This structure, through the straight section 411 on the side and the small arc with a central angle of 45°~80°, allows the battery cell to expand towards the area of ​​the first arc-shaped section 421 on the side, thereby accelerating the shaping speed.

[0040] Specifically, in some other implementations, such as Figure 1 and 7 As shown, the extrusion section 410 includes an arc segment 413; the two ends of the arc segment 413 are respectively connected to one end of two different first arc segments 421 to form a concentric curve segment; the relationship between the arc circumference D2 of this curve segment and the thickness D1 of the wound body 400 satisfies: D2=(1.5~2)*D1. Since the upper and lower sides of the wound body 400 are limited by pressure plates during side hot pressing, full coverage hot pressing in the thickness (height) direction is achieved, and the deformation only exists in the arc area; without any change in thickness (height). This structure, through the reasonable matching of the diameter of the curve segment and the thickness of the wound body 400, ensures that the area corresponding to the corner segment is subjected to more uniform force, and has better safety performance such as lithium plating at the corner, while also reducing the width; thereby improving the safety and stability of use.

[0041] Specifically, in some of its implementations, such as Figure 1 and 8 As shown, the extrusion section 410 includes at least one second arcuate segment 414 and at least one straight segment 415; the second arcuate segment 414 and the straight segment 415 are arranged alternately; the second arcuate segment 414 is recessed towards the interior of the wound body 400; and one end of the second arcuate segment 414 and / or one end of the straight segment 415 are connected to the first arcuate segment. This structure, through the extrusion of the straight segment 415 and the buffering effect of the recess of the second arcuate segment 414, can reduce the extrusion deformation of the first arcuate segment 421, thereby effectively reducing the width value while effectively controlling the thickness of the wound body 400; thus improving the safety and stability of use. In some embodiments, such as... Figure 8As shown, the length d1 of the straight segment 415 satisfies: 1mm ≤ d1 ≤ 7mm. d1 can be 1mm, 2mm, 3mm, 4mm, 6mm, 7mm, etc.; preferably 5mm. The depth d2 of the second arc segment 414 satisfies: 60μm ≤ d2 ≤ 200μm. d2 can be 60μm, 70μm, 80μm, 90μm, 100μm, 150μm, 160μm, 165μm, 190μm, 200μm, etc.; preferably 150μm. This structure achieves the longest possible circumference of the bare cell side arc by forming (uniform) regular spot imprints on the side of the cell, and a larger gap between layers at the edge corners, resulting in better lithium plating effect at corners.

[0042] Specifically, in some implementations, such as Figure 1 , 5 As shown in Figure 6, the extrusion portion 410 includes a protruding section 412; the connecting portion 420 includes a recessed section 422; one end of the protruding section 412 is connected to one end of the recessed section 422; the other end of the recessed section 422 is connected to one horizontal section 401; the other end of the protruding section 412 is connected to another horizontal section 401. The protruding section 412 can be an irregular protrusion, etc.; the recessed section 422 can be an irregular concave block, etc. Further, as... Figure 5 As shown, in some other embodiments, the recessed section 422 is disposed above the protruding section 412 to form a shape that is convex at the bottom and concave at the top, thereby reducing the width of the battery cell. Further, as... Figure 6 As shown, in other embodiments, the recessed section 422 is disposed below the protruding section 412 to form a convex-concave shape, thereby reducing the width of the battery cell.

[0043] Specifically, in some implementations, such as Figure 1 and 4 As shown, the relationship between the width L0 of the wound body 400 before extrusion, the width L1 of the wound body 400 after extrusion, and the thickness D1 of the wound body 400 before or after extrusion satisfies: D1*4% < L0-L1 < D1*40%. When the reduction in extrusion width is greater than or equal to 40% of the cell thickness, the cell exhibits electrode wrinkling and deformation, and the cell thickness increases, thus affecting the safety and stability of use.

[0044] Example 1

[0045] Use bare battery cells with a thickness of 5.0mm and a width of 62.9mm, such as... Figure 3As shown, the upper pressure plate 51 and the lower pressure plate 52 are used to limit and press the upper and lower surfaces of the bare cell to prevent its height from deforming beyond the standard range; then the two hot pressing push blocks 53 perform hot pressing from the left and right sides of the bare cell to promote a width reduction of 0.5mm; thus forming a width reduction / cell thickness = 0.1.

[0046] Example 2

[0047] The difference between Example 2 and Example 1 is that the width reduction is 1.0 mm; and the width reduction / cell thickness = 0.2.

[0048] Example 3

[0049] The difference between Example 3 and Example 1 is that the width reduction is 1.5 mm; and the width reduction / cell thickness = 0.3.

[0050] Comparative Example 1

[0051] The difference between Example 4 and Example 1 is that the width reduction is 0.2 mm; and the width reduction / cell thickness = 0.04.

[0052] Comparative Example 2

[0053] The difference between Comparative Example 2 and Example 1 is that the width reduction is 2.0 mm; and the width reduction / cell thickness = 0.4.

[0054] Comparative Example 3

[0055] The difference between Comparative Example 4 and Example 1 is that the width reduction is 2.4 mm; and the width reduction / cell thickness = 0.48.

[0056] Table 1 - Relationship between cell width reduction and cell deformation

[0057]

[0058]

[0059] Conclusion: Taking a cell thickness of 5.0mm and a cell width of 62.9mm as an example, if the cell thickness * 4% < the extrusion width reduction < the cell thickness * 40%, that is, when the extrusion width reduction is less than 2.0mm, the cell will not deform and can be used normally. When the width reduction is ≥ 2.0mm, the cell will begin to deform, wrinkle, etc., which will affect normal use.

[0060] This utility model also proposes a secondary battery, which includes a cell structure. The specific structure of the cell structure is as described in the above embodiments. Since this secondary battery adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0061] A rechargeable battery, also known as a secondary battery or accumulator, is a battery that can be recharged after being discharged, allowing the active materials to be reactivated and reused. Utilizing the reversibility of chemical reactions, a new battery can be constructed; that is, after a chemical reaction converts into electrical energy, the electrical energy can be used to repair the chemical system, and then the chemical reaction can be converted back into electrical energy. Therefore, it is called a secondary battery (rechargeable battery). The main types of rechargeable batteries on the market include nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid (or lead-acid) batteries, lithium-ion batteries, and polymer lithium-ion batteries.

[0062] The present invention also proposes an electrical device, which includes a secondary battery. The specific structure of the secondary battery is as described in the above embodiments. Since the present electrical device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0063] The electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose special limitations on the above-mentioned electrical equipment.

[0064] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0065] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, this utility model is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on this utility model are within the protection scope of this utility model. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on this utility model.

Claims

1. A battery cell structure, characterized in that: The device includes a first electrode and a second electrode, and a separator disposed between the first electrode and the second electrode; the first electrode, the separator, and the second electrode are sequentially wound to form a wound body; the wound body has at least one corner segment and at least one horizontal segment; the corner segment has a compression portion and at least one connecting portion; one end of the compression portion and / or one end of the connecting portion is connected to the horizontal segment.

2. The cell structure according to claim 1, characterized in that: The connecting portion includes a first arc-shaped segment; one end of the first arc-shaped segment is connected to one end of the horizontal segment; the other end of the first arc-shaped segment is connected to one end of the extrusion portion.

3. The cell structure according to claim 2, characterized in that: The extrusion section includes a straight section; the two ends of the straight section are respectively connected to one side of two different first arc-shaped sections.

4. The cell structure according to claim 3, characterized in that: The central angle corresponding to the first arc segment is α, and α satisfies: 45°≤α≤80°.

5. The cell structure according to claim 2, characterized in that: The extrusion section includes an arc segment; the two ends of the arc segment are respectively connected to one end of two different first arc segments to form a concentric curve segment. The relationship between the arc circumference of the curve segment, D2, and the thickness of the winding body, D1, satisfies: D2 = (1.5 ~ 2) * D1.

6. The cell structure according to claim 2, characterized in that: The extrusion section includes at least one second arc-shaped segment and at least one straight segment; the second arc-shaped segment and the straight segment are arranged alternately; the second arc-shaped segment is recessed toward the interior of the winding body; and one end of the second arc-shaped segment and / or one end of the straight segment is connected to the first arc-shaped segment.

7. The cell structure according to claim 1, characterized in that: The extrusion section includes a protruding section; the connecting section includes a recessed section; one end of the protruding section is connected to one end of the recessed section; the other end of the recessed section is connected to one of the horizontal sections; and the other end of the protruding section is connected to another of the horizontal sections.

8. The cell structure according to any one of claims 1 to 7, characterized in that: The relationship between the width L0 of the wound body before extrusion, the width L1 of the wound body after extrusion, and the thickness D1 of the wound body before or after extrusion satisfies: D1*4% < L0-L1 < D1*40%.

9. A secondary battery, characterized in that: Includes the cell structure described in any one of claims 1 to 8.

10. An electrical appliance, characterized in that: Includes the secondary battery as described in claim 9.

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