An electrode tab of an electrode, an electrode, and a secondary battery

Abstract

The utility model belongs to the battery technical field, concretely relates to a kind of battery cell pole piece, battery cell and secondary battery;Wherein, the battery cell pole includes current collector and the active material layer connected to the current collector at least one side surface;The active material layer is provided with at least one first recess on the side surface away from the current collector;The inside of the first recess is provided with at least one second recess;The recess direction of the second recess is set from the active material layer towards the direction of the current collector.The utility model can increase infiltration efficiency, and can increase electrolyte storage space, also be conducive to improving corner lithium precipitation effect.

Description

Technical Field

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

[0002] Lithium-ion batteries have been widely used as power batteries. With increasingly fierce market competition, major lithium-ion battery companies are constantly exploring and improving the performance and manufacturing processes of power lithium-ion batteries. As the core component of lithium-ion batteries, the battery cell is typically produced using two methods: stacking and winding. Currently, improving energy density mainly relies on optimizing battery structure, improving positive and negative electrode materials, and applying lithium replenishment technology. Among these, optimizing battery structure plays a crucial role in improving energy density. By changing the shape, size, and connection method of the battery, the volumetric energy density and gravimetric energy density of the battery can be effectively improved.

[0003] Currently, most commercially available lithium-ion batteries adopt a wound structure. However, for wound lithium-ion batteries, lithium deposition is prone to occur at the corners of the negative electrode during cyclic charging and discharging, thus requiring embossing of the cell electrodes. However, some existing embossing structures, while improving the corner lithium deposition problem, suffer from issues such as process breakage and embossing cracks due to the excessive embossing height causing random stress release. Utility Model Content

[0004] The purpose of this utility model is to provide a battery cell electrode sheet that addresses the shortcomings of existing technologies by solving the problem of process breakage and embossing cracks caused by excessive embossing height leading to random stress release.

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

[0006] A battery cell electrode includes a current collector and an active material layer connected to at least one side surface of the current collector; the active material layer has at least one first groove on the side surface away from the current collector; the first groove has at least one second groove inside; the recessed direction of the second groove is arranged from the active material layer toward the current collector.

[0007] Preferably, the second groove has a first inclined side and a second inclined side that are inclined to each other inside in the cross-sectional direction;

[0008] Furthermore, the angle between the first hypotenuse and its horizontal plane, and the angle between the second hypotenuse and its horizontal plane, is α; wherein α satisfies: 70°≤α≤85°.

[0009] Preferably, the depth of the second groove is less than 60 percent of the depth h3 of the first groove.

[0010] Preferably, the cross-section of the first groove is a circular or square embossed groove.

[0011] And / or, the second groove is a dot-shaped body at the opening in the cross-sectional direction; or the second groove is a line-shaped body at the opening in the cross-sectional direction.

[0012] Preferably, the linear body is a linear structure with a semi-circular cross-section or a linear structure with a rectangular cross-section.

[0013] Preferably, the relationship between the depth h1 of the dot-like body and the thickness H0 of the active material layer satisfies: h1 < 40% * H0;

[0014] And / or, the relationship between the depth h2 of the linear body and the thickness H0 of the active material layer satisfies: h2 < 40% * H0.

[0015] Preferably, the relationship between the depth h1 of the point body and the width d1 of the opening of the point body in the cross-sectional direction satisfies: h1=A*d1; where A satisfies: 1.5≤A≤3.0;

[0016] And / or, the relationship between the width d2 of the linear body and the depth h2 of the linear body satisfies: d2:h2=(0.4~2):1.

[0017] Preferably, the relationship between the coverage area S1 of all the second grooves and the surface area S2 of the inner bottom of the first groove satisfies: S1:S2=(0.3~0.4);

[0018] And / or, the relationship between the coverage area S1 of all the second grooves and the area S3 of the opening of the first groove satisfies: S1:S3=(0.5~0.6).

[0019] This utility model also discloses a battery cell, including the aforementioned battery cell electrode.

[0020] This utility model also discloses a secondary battery, including the aforementioned battery cell.

[0021] The beneficial effects of this utility model are as follows: by adding multiple first grooves on the active material layer and adding multiple second grooves inside the first grooves, the specific surface area of ​​the cell electrode is increased, thereby objectively shortening the ion transport distance and extending the electrolyte wetting path. It can also shorten the height of the first grooves to solve the problem of process breakage and embossing cracks caused by the random release of stress due to excessively high embossing height. This increases the wetting efficiency, increases the electrolyte storage space, and also helps to improve the corner lithium plating effect under the same type of embossing structure. Attached Figure Description

[0022] The following will refer to the appendix. Figures 1-6 This section describes the features, advantages, and technical effects of exemplary embodiments of the present invention.

[0023] Figure 1 This is a front view of a battery cell electrode sheet according to an embodiment of the present invention;

[0024] Figure 2 This is a top view of the electrode sheet of a battery cell according to one embodiment of the present utility model;

[0025] Figure 3 This is a front view of the electrode sheet of a battery cell according to one embodiment of the present invention;

[0026] Figure 4 This is a top view of the electrode sheet of another embodiment of the present invention;

[0027] Figure 5 This is a front view of the battery cell electrode sheet according to another embodiment of the present invention;

[0028] Figure 6 This is a coordinate diagram showing the depth values ​​of the first and second grooves of the battery cell electrode sheet according to an embodiment of the present invention.

[0029] In the figure: 1-current collector; 2-active material layer; 3-first groove; 4-second groove; 401-dot-shaped body; 402-line-shaped body; 41-first inclined side; 42-second inclined side. Detailed Implementation

[0030] 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 intended to particularly describe embodiments and not to limit the scope of this 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.

[0031] 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 embodiment description, "multiple" refers to two or more, unless otherwise specifically defined.

[0032] The term 'embodiment' means that a particular feature, structure, or characteristic described exists 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 mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] 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.

[0034] 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 also refer to a mechanical connection or an electrical connection. They can be directly connected or indirectly connected through an intermediate medium, manifesting as internal communication between two components or an 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.

[0035] The following is in conjunction with the appendix Figures 1-6 The present invention will be described in further detail, but this is not intended to limit the scope of the present invention.

[0036] like Figure 1 As shown, in one embodiment of the present invention, the battery cell electrode includes a current collector 1 and an active material layer 2 connected to at least one side surface of the current collector 1; the active material layer 2 has at least one first groove 3 on the side surface away from the current collector 1; the first groove 3 has at least one second groove 4 inside; the recessed direction of the second groove 4 is set from the active material layer 2 toward the current collector 1.

[0037] The technical solution of this utility model adds multiple first grooves to the active material layer, and adds multiple second grooves inside the first grooves, which helps to increase the specific surface area of ​​the cell electrode, thereby objectively shortening the ion transport distance and extending the electrolyte wetting path. It can also shorten the height of the first grooves to solve the problem of process breakage and embossing cracks caused by the random release of stress due to excessive embossing height. This increases the wetting efficiency, increases the electrolyte storage space, and also helps to improve the corner lithium plating effect under the same type of embossing structure.

[0038] Specific surface area refers to the total surface area of ​​a substance per unit mass or unit volume, and its unit is usually m². 2 / g (square meter / gram) or m 2 / cm 3 (square meters per cubic centimeter). It essentially describes the "abundance" of a material's surface; the finer and more porous the surface, the larger its specific surface area.

[0039] Specifically, in some embodiments, the relationship between the coverage area S1 of all the second grooves and the surface area S2 of the inner bottom of the first groove satisfies: S1:S2 = (0.3~0.4); and the relationship between the coverage area S1 of all the second grooves and the area S3 of the opening of the first groove satisfies: S1:S3 = (0.5~0.6). This structure can ensure overall mechanical strength and can ensure improved performance.

[0040] Specifically, in some implementations, such as Figure 1 and 3 As shown, Figure 1 , 3 As shown in Figure 5, the second groove 4 has a first inclined side 41 and a second inclined side 42 that are inclined to each other and connected in the cross-sectional direction; and the angle between the first inclined side 41 and its horizontal plane and the angle between the second inclined side 42 and its horizontal plane is α; wherein, α satisfies: 70°≤α≤85°; α can be 70°, 72°, 74°, 74.5°, 75°, 76°, 78°, 80°, 85°, etc.; preferably 75°. This structure ensures structural strength by setting a suitable angle α. If α<70°, stress concentration in the second groove 4 will lead to fracture; if α>85°, the sidewall of the second groove 4 will collapse; that is, exceeding the upper and lower limits, both will cause insufficient stability of the etched hole, manifesting as hole collapse. Here, the cross-sectional direction is the vertical plane direction along the height direction of the central axis at the opening of the second groove 4.

[0041] Specifically, in some embodiments, the cross-section of the first groove 3 is a circular or square embossed groove to facilitate production and processing; and it can also increase the electrolyte storage space and improve the lithium plating effect at corners.

[0042] Specifically, in some of these implementations, such as Figure 1 and 2 As shown, the opening of the second groove 4 in the cross-sectional direction is a dot-like body 401. In some embodiments, such as... Figure 2 and 3 As shown, the width d1 of the dot-like structure 401 satisfies: 50nm ≤ d1 ≤ 300nm; d1 can be 50nm, 55nm, 70nm, 80nm, 105nm, 250nm, 260nm, 280nm, 290nm, 300nm, etc.; preferably 80nm. This structure requires a process window width greater than 50nm to avoid easy clogging of the nanostructure (due to the electrolyte solubilized ion diameter of approximately 1nm); and requires a process window width less than 300nm to avoid nano-effect failure (due to the critical size of lithium dendrites being 300nm). Further, as... Figure 3 As shown, the width direction is either left-right or horizontal.

[0043] Specifically, in some implementations, such as Figure 2 and 3 As shown, the relationship between the depth h1 of the point body 401 and the width d1 of the opening of the point body 401 in the cross-sectional direction satisfies: h1 = A*d1; where A satisfies: 1.5 ≤ A ≤ 3.0; that is, h1 = 1.5*d1, h1 = 1.6*d1, h1 = 1.7*d1, h1 = 1.8*d1, h1 = 2.0*d1, h1 = 2.1*d1, h1 = 2.2*d1, h1 = 2.5*d1, h1 = 3.0*d1, etc.; preferably h1 = 2.5*d1. When h1 > 3.0*d1, the structural support is insufficient, which easily leads to hole collapse (sidewall collapse). When h1 < 1.5*d1, electrolyte wetting is difficult and capillary effect cannot be guaranteed. Furthermore, as... Figure 6 As shown, the depth h1 of the dot-shaped body 401 and the depth of the second groove 4 (embossing groove) are respectively taken.

[0044] Specifically, in some implementations, such as Figure 3 As shown, the relationship between the depth h1 of the dot-like body 401 and the thickness H0 of the active material layer 2 satisfies: h1 < 40% * H0. That is, h1 can be 10% * H0, 15% * H0, 18% * H0, 20% * H0, 22% * H0, 28% * H0, 30% * H0, 35% * H0, 40% * H0, etc.; preferably 35% * H0. This structure ensures that the thermal radiation zone does not affect the current collector when h1 is less than 40% * H0, thereby reducing additional risks.

[0045] In some embodiments, the number of dot-like bodies 401 inside the first groove 3 is 9 to 30; the number of first grooves 3 is 9 to 30. This density is related to the silicon expansion rate; the higher the expansion rate, the more dots there are (the more space is reserved, and the smaller the dot spacing). The quantity value is calculated as X * silicon system expansion rate (%), where X is the correlation coefficient, rounded up.

[0046] Specifically, in other implementations, such as Figure 1 and 4 As shown, the opening of the second groove 4 in the cross-sectional direction is a linear body 402; further, the linear body 402 is a linear structure with a semi-circular cross-section or a linear structure with a rectangular cross-section. In some embodiments, such as... Figure 4 and 5As shown, the width d2 of the opening in the cross-sectional direction of the linear body 402 satisfies: 50nm ≤ d2 ≤ 300nm; d2 can be 50nm, 55nm, 70nm, 80nm, 105nm, 250nm, 260nm, 280nm, 290nm, 300nm, etc.; preferably 80nm. This structure requires a process window width greater than 50nm to avoid easy clogging of the nanostructure (due to the electrolyte solubilized ion diameter of about 1nm); and requires a process window width less than 300nm to avoid nano-effect failure (due to the critical size of lithium dendrites being 300nm). Further, as... Figure 3 As shown, the width direction is either left-right or horizontal.

[0047] In some implementation methods, such as Figure 5 As shown, the relationship between the depth h2 of the linear body 402 and the thickness H0 of the active material layer 2 satisfies: h2 < 40% * H0. That is, h2 can be 10% * H0, 15% * H0, 18% * H0, 20% * H0, 22% * H0, 28% * H0, 30% * H0, 35% * H0, 40% * H0, etc.; preferably 35% * H0. This structure, by ensuring h2 is below 40% H0, prevents the thermal radiation zone from affecting the current collector, thereby reducing additional risks. Furthermore, as... Figure 6 As shown, the depth h2 of the linear body 402 and the depth of the second groove 4 (embossing groove) are respectively determined.

[0048] Specifically, in some implementations, such as Figure 5 As shown, the relationship between the width d2 of the opening in the cross-sectional direction of the linear body 402 and the depth h2 of the linear body 402 satisfies: d2:h2=(0.4~2):1. This structure can ensure the overall mechanical strength and also ensure the improvement effect.

[0049] Specifically, in some embodiments, the depth of the second groove 4 is less than 60% of the depth h3 of the first groove 3. Wherein, when the second groove 4 is a dot-shaped body 402, the relationship between the depth h3 of the first groove and the depth h2 of the dot-shaped body 401 satisfies: h1 < 60% * h3. This structure ensures the stability of the overall structure and also ensures improved performance.

[0050] The number of linear bodies 402 inside the first groove 3 is 9 to 30; the number of first grooves 3 is 9 to 30. This density is related to the silicon expansion rate; the higher the expansion rate, the more dots (the more space is reserved, and the smaller the dot spacing). The quantity value = X * silicon system expansion rate (%); X is the correlation coefficient, rounded up. Furthermore, the linear bodies 402 use a zigzag structure with a limited angle of 1° to 80°; or the linear bodies 402 use a dovetail shape (to resist shear force and prevent strip breakage and fragmentation), and the use of a straight line shape is strictly prohibited (as it easily leads to crack propagation).

[0051] Table 1 Correspondence between Embossing Height and Etching Depth

[0052]

[0053]

[0054] Table 2 embossing point range limitation

[0055]

[0056] The fabrication scheme for the battery cell electrode:

[0057] Path 1 (two-step method): After the battery cell electrode sheet is embossed by a embossing roller and a rubber roller to form a circular / square second groove, a laser is used to perform dot-shaped laser etching in the groove to form a composite nanostructure of the second groove 3 and the second groove 4.

[0058] Path 2 (one-step method): When making the embossing roller for the battery cell electrode sheet, the sphere radius / cube edge defines a multi-level protrusion structure (small protrusions superimposed on large protrusions) and is formed in one step with the rubber roller, forming a composite nanostructure of the second groove 3 and the second groove 4 at the extrusion point.

[0059] During the test, the battery cell electrode sheet is pressed by embossing roller and rubber roller to form a second groove 4, so that the second groove 4 and its first inclined side 41 and second inclined side 42 are respectively at an angle α with the horizontal plane where they are located; the value of α is shown in the experimental table below. Then the battery cell electrode sheet is wound to form a corresponding battery cell structure; thereby detecting whether the appearance of the battery cell structure has collapsed holes.

[0060] Experimental Table 1

[0061]

[0062]

[0063] In summary, this structure ensures structural strength by setting an appropriate included angle α. If α < 70°, stress concentration occurs in the second groove 4, leading to fracture; if α > 85°, the sidewall of the second groove 4 collapses. Both exceeding the upper and lower limits result in insufficient stability of the etched hole, manifesting as hole collapse.

[0064] This utility model also proposes a battery cell, which includes a positive electrode plate and a negative electrode plate, and a separator connecting the positive electrode plate and the negative electrode plate; the positive electrode plate and / or the negative electrode plate are the aforementioned battery cell electrode plates, and the specific structure of the battery cell refers to the above embodiments. Since this 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.

[0065] The positive electrode includes a positive current collector and a positive active material layer, with the active material layer coated on the surface of the current collector. The current collector can be made of aluminum, and the active material layer includes the active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer, with the active material layer coated on the surface of the current collector. The current collector can be made of copper, and the active material layer includes the active material, which can be carbon or silicon, etc. The separator can be made of PP (polypropylene) or PE (polyethylene), etc.

[0066] This utility model also proposes a secondary battery, which includes a battery cell. The specific structure of the battery cell 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.

[0067] A rechargeable battery, also known as a secondary battery or accumulator battery, 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.

[0068] 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.

[0069] 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 electrode, characterized in that: The device includes a current collector and an active material layer connected to at least one side surface of the current collector; the active material layer has at least one first groove on the side surface away from the current collector; the first groove has at least one second groove inside; the recessed direction of the second groove is set from the active material layer toward the current collector.

2. The cell electrode sheet according to claim 1, characterized in that: The second groove has a first inclined side and a second inclined side that are inclined to each other inside in the cross-sectional direction; Furthermore, the angle between the first hypotenuse and its horizontal plane, and the angle between the second hypotenuse and its horizontal plane, is α; wherein α satisfies: 70°≤α≤85°.

3. The cell electrode sheet according to claim 1, characterized in that: The depth of the second groove is less than 60 percent of the depth h3 of the first groove.

4. The cell electrode sheet according to claim 1, characterized in that: The cross-section of the first groove is a circular or square embossed groove; And / or, the second groove is a dot-shaped body at the opening in the cross-sectional direction; or the second groove is a line-shaped body at the opening in the cross-sectional direction.

5. The cell electrode sheet according to claim 4, characterized in that: The linear body is a linear structure with a semi-circular cross-section or a linear structure with a rectangular cross-section.

6. The cell electrode sheet according to claim 4, characterized in that: The relationship between the depth h1 of the dot-like body and the thickness H0 of the active material layer satisfies: h1 < 40% * H0; And / or, the relationship between the depth h2 of the linear body and the thickness H0 of the active material layer satisfies: h2 < 40% * H0.

7. The cell electrode sheet according to claim 4 or 5, characterized in that: The relationship between the depth h1 of the point-like body and the width d1 of the opening of the point-like body in the cross-sectional direction satisfies: h1=A*d1; where A satisfies: 1.5≤A≤3.0; And / or, the relationship between the width d2 of the linear body and the depth h2 of the linear body satisfies: d2:h2=(0.4~2):

1.

8. The cell electrode sheet according to claim 1, characterized in that: The relationship between the coverage area S1 of all the second grooves and the surface area S2 of the inner bottom of the first groove is satisfied as follows: S1:S2=(0.3~0.4); And / or, the relationship between the coverage area S1 of all the second grooves and the area S3 of the opening of the first groove satisfies: S1:S3=(0.5~0.6).

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

10. A secondary battery, characterized in that: Includes the battery cell as described in claim 9.

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