Pole piece, battery cell and secondary battery

Abstract

The utility model belongs to the technical field of batteries, and particularly relates to a pole piece, a battery cell and a secondary battery. Wherein the pole piece comprises a current collector and an active material layer connected to at least one side surface of the current collector; at least one avoiding groove is formed in the active material layer; the avoiding grooves respectively penetrate through the active material layer and the current collector; when the pole piece is in a winding state, the current collector is provided with at least one corner section and at least one straight section which are alternately arranged; and the avoiding grooves are formed in the corner sections. According to the utility model, the problem of low electrolyte retention capacity can be solved, and the cycle performance of the battery is improved.

Description

Technical Field

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

[0002] Lithium-ion batteries are a type of rechargeable battery that primarily relies on the movement of lithium ions between the positive and negative electrodes to function. The chemical properties of the materials in lithium-ion batteries are extremely reactive, which is why they are widely used in various fields. However, these properties also place high demands on the packaging, processing, storage, and environmental conditions of lithium-ion batteries.

[0003] However, during the charging and discharging process of lithium-ion batteries, the electrolyte plays a role in transporting lithium ions between the positive and negative electrodes. However, 3C products are prone to insufficient electrolyte during the cycling process, which affects the battery cycle performance, thereby reducing the energy density of the cell and shortening the battery life. Utility Model Content

[0004] The purpose of this invention is to provide an electrode that addresses the shortcomings of existing technologies and solves the technical problem of insufficient electrolyte during the cycling process.

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

[0006] An electrode includes a current collector and an active material layer connected to at least one surface of the current collector; the electrode has at least one clearance groove; and the clearance groove passes through the active material layer and the current collector respectively.

[0007] When the electrode sheet is wound into a core, the electrode sheet has at least one corner segment and a straight segment that are alternately arranged; and the clearance groove is provided on the corner segment.

[0008] Preferably, at least two clearance grooves are provided along the width direction of the electrode sheet, and they are located at the two corners of the corner segment; and the clearance grooves extend to the edge of the electrode sheet.

[0009] Preferably, the length of the clearance groove along the length direction of the electrode is L2, satisfying: 0.2mm≤L2≤4mm.

[0010] Preferably, the electrode sheet is further provided with at least one liquid collector; the liquid collector is arranged sequentially along the length direction of the electrode sheet; and in the width direction of the electrode sheet, the liquid collector is disposed between the two clearance grooves.

[0011] Preferably, the liquid collector has a recessed structure; the recessed structure is recessed from the surface of the active material layer toward the surface of the liquid collector.

[0012] Preferably, the distance between two adjacent recessed structures is d2, which satisfies: 2mm≤d2≤10mm;

[0013] And / or, the depth of the recessed structure is h1, satisfying: 60μm≤h1≤120μm;

[0014] And / or, the relationship between the depth h1 of the recessed structure and the thickness h2 of the active material layer satisfies: h1 < h2.

[0015] Preferably, the electrode sheet is further provided with an electrode tab groove; the electrode tab groove is disposed through the thickness direction of the active material layer;

[0016] Furthermore, the distance between the tab groove and its adjacent recessed structure is d1, which satisfies: 3≤d1≤5mm.

[0017] This utility model also discloses a battery cell, including a first electrode, 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; an aluminum-plastic film is sleeved on the outer surface of the wound body; the first electrode and the second electrode are the electrodes described above.

[0018] Preferably, the length L of the avoidance groove in the second electrode is... 02 The length L of the avoidance groove in the first electrode 01 The relationship between L satisfies: 01 >L 02 Furthermore, the first electrode is the positive electrode; the second electrode is the negative electrode.

[0019] And / or, an adsorption filling material is provided between the aluminum-plastic film and the clearance groove; wherein, the adsorption filling material is graphene or carbon nanotubes.

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

[0021] The beneficial effect of this utility model is that, by providing at least one clearance groove on the electrode sheet, and the clearance groove corresponding to the corner of the electrode sheet in the winding state, the clearance groove can effectively increase the contact area between the corner segment and the cell body formed therein and the electrolyte, thereby facilitating the wetting between the electrolyte and the electrode sheet, thus solving the problem of low electrolyte retention and improving the battery cycle performance. 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 schematic diagram of the structure of an electrode sheet according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure of an electrode sheet according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of an electrode sheet according to an embodiment of the present invention;

[0026] Figure 4 This is a cross-sectional view of the AA section of an electrode sheet according to an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the disassembled assembly of a battery cell according to an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention.

[0029] In the diagram: 11-Current collector; 12-Active material layer; 121-Electrode groove; 101-Corner section; 102-Straight section; 2-Avoidance groove; 3-Current collector; 31-Recessed structure; 100-First electrode; 200-Second electrode; 300-Separating membrane; 400-Aluminum-plastic film; 500-Wound body; 600-Adsorption filling material. 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 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.

[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 description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0032] 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.

[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 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.

[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 this utility model, the electrode sheet includes a current collector 11 and an active material layer 12 disposed on at least one side surface of the current collector 11; the electrode sheet is provided with at least one clearance groove 2; and the clearance groove 2 penetrates the active material layer 12 and the current collector 11 respectively; when the electrode sheet is wound into a core, the electrode sheet has at least one corner segment 101 and a straight segment 102 arranged alternately; and the clearance groove 2 is disposed on the corner segment 101. The current collector 11 can be a positive current collector and / or a negative current collector. Further, both the positive and negative current collectors are provided with clearance grooves 2.

[0037] The technical solution of this utility model is to provide at least one clearance groove on the electrode sheet, and the clearance groove corresponds to the corner of the electrode sheet in the winding state. The clearance groove can effectively increase the contact area between the corner section and the cell body formed therein and the electrolyte, thereby facilitating the wetting between the electrolyte and the electrode sheet, thus solving the problem of low electrolyte retention and improving the battery cycle performance.

[0038] Specifically, in some implementations, such as Figure 1 and 2 As shown, multiple clearance grooves 2 are provided along the width direction (0Y axis direction) of the electrode sheet, and are located at the two corners of the corner segment 101; and the clearance grooves 2 extend to the edge of the electrode sheet. Wherein, as Figure 1As shown, two clearance grooves 2 are provided in the width direction of the current collector 11, and are symmetrically arranged at the upper and lower corners of the corner segment 101. The clearance grooves 2 penetrate the active material layer 12 and the current collector 11 in the thickness direction, and extend to the edges of the current collector 11 and the active material layer 12 in the width direction. In other words, by cutting off the upper and lower sides of the corner segment of the wound electrode to form clearance grooves 2, sufficient space is provided at the four corners of the wound cell, reducing corner cracking during cycling, thereby improving assembly stability and safety. It also solves the problem of electrolyte retention and improves battery cycle performance.

[0039] Specifically, in some implementations, such as Figure 1 As shown, along the length of the electrode, the length of the clearance groove 2 is L2, satisfying: 0.2mm ≤ L2 ≤ 4mm. That is, the clearance groove 2 can be rectangular, square, or semi-circular; specifically, when the clearance groove 2 is semi-circular, its diameter is 0.1mm to 2mm. When the clearance groove 2 is rectangular, its length and width are 0.1mm to 2mm respectively. When the clearance groove 2 is square, its side length is 0.1mm to 2mm. This structure, with its appropriately sized clearance groove 2, ensures the amount of electrolyte stored, as well as the overall structural stability and safety during use.

[0040] Specifically, in some implementations, such as Figure 1 and 2 As shown, the electrode also has at least one liquid collector 3; the liquid collector 3 is arranged sequentially along the length direction (0X axis direction) of the electrode; and the liquid collector 3 is disposed between two clearance grooves 2 in the width direction (0Y axis direction) of the electrode. That is, liquid accumulation treatment is performed on the electrode to further increase the electrolyte retention and thus improve the cycle performance of the battery. In this case, the current collector 11 is a positive electrode current collector (cathode current collector); the current collector 11 may not be a negative electrode current collector (anode current collector) or the current collector 11 may be a negative electrode current collector (anode current collector).

[0041] Specifically, in some implementations, such as Figure 2 and 3 As shown, the current collector 3 is a recessed structure 31; the recessed structure 31 is recessed from the surface of the active material layer 12 toward the surface of the current collector 11. That is, the surface of the active material layer 12 between the clearance grooves 2 on the upper and lower sides of the same corner segment is embossed to form the recessed structure 31, which can further increase the electrolyte retention and thus improve the cycle performance of the battery.

[0042] Specifically, in some implementations, such as Figure 3 and 4As shown, the distance between two adjacent recessed structures 31 is d2, satisfying: 2 mm ≤ d2 ≤ 10 mm; the depth of the recessed structure 31 is h1, satisfying: 60 μm ≤ h1 ≤ 120 μm; and the relationship between the depth h1 of the recessed structure 31 and the thickness h2 of the active material layer 12 satisfies: h1 < h2. That is to say, the recessed structures 31 with appropriate spacing differences and appropriate depths can ensure the storage amount of the electrolyte, and can also ensure the overall structural stability and guarantee the safety of use.

[0043] Specifically, in some embodiments, as Figure 3 shown, a tab groove 121 is further provided on the electrode sheet; the tab groove 121 is arranged through the thickness direction (OZ axis direction) of the active material layer 12; and the distance between the tab groove 121 and its adjacent recessed structure 31 is d1, satisfying: 3 ≤ d1 ≤ 5 mm. That is to say, the position of the recessed structure 31 bypasses the tab groove 121 to avoid affecting the use of the tab structure; thus, the storage amount of the electrolyte can be ensured, and the overall structural stability can also be ensured, guaranteeing the safety of use.

[0044] The present utility model further provides an electric core, as Figure 5 and 6 shown, the electric core includes a first electrode sheet 100, a second electrode sheet 200, and a separator 300 disposed between the first electrode sheet 100 and the second electrode sheet 200; the first electrode sheet 100, the separator 300, and the second electrode sheet 200 are wound in sequence to form a wound body 500; an aluminum-plastic film 400 is sleeved on the outer surface of the wound body 500; the first electrode sheet 100 and / the second electrode sheet 200 are electrode sheets. The specific structure of the electrode sheet refers to the above embodiments. Since this electric core adopts all the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated herein one by one. Among them, the first electrode sheet 100 is a positive electrode sheet (cathode sheet); the second electrode sheet 200 is a negative electrode sheet (anode sheet).

[0045] Specifically, in some embodiments, as Figure 6 shown, an adsorption and filling material 600 is provided between the aluminum-plastic film 400 and the avoidance groove 2. Among them, the adsorption and filling material 600 can be graphene, carbon nanotubes, etc. This structure dots graphene, carbon nanotubes and other porous materials at the four corners of the aluminum-plastic film during the top-sealing process, so as to release the electrolyte after the electrolyte is exhausted and improve the cycle performance.

[0046] Specifically, in some embodiments, as Figure 5As shown, the relationship between the width D1 of the first electrode 100, the width D2 of the second electrode 200, and the width D3 of the separator 300 satisfies: D2-D1 = (1.0mm~1.6mm); preferably 1.1mm. D3-D2 = (2.0mm~2.6mm), preferably 2.3mm.

[0047] Specifically, in some implementations, such as Figure 5 As shown, the length L of the clearance groove 2 in the second electrode 200 02 The length L of the avoidance groove 2 in the first electrode 100 01 The relationship between L satisfies: 01 >L 02 In other words, the radius of the anode cut-off clearance groove 2 (semicircle) is smaller than the radius of the cathode cut-off clearance groove 2 (semicircle), which ensures the electrolyte storage capacity, overall structural stability, and safety of use.

[0048] Specifically, in some implementations, such as Figure 1 and 6 As shown, along the length of the winding body 500, the distance L1 between the center points of two adjacent clearance grooves 2 and the width L3 of the winding body 500 satisfy the following relationship: L3-1mm≤L1≤L3+1mm. Preferably, L3=L1. Furthermore, the first electrode 100 is a positive electrode, and the second electrode 200 is a negative electrode. That is, the distance L1 between the center points of two adjacent clearance grooves 2 is equal to the width L3 of the winding body 500, thereby ensuring the electrolyte storage capacity, overall structural stability, and safety during use.

[0049] 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 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, 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 a negative active material, such as carbon or silicon. The separator 300 can be made of PP (polypropylene) or PE (polyethylene), etc.

[0050] 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.

[0051] A rechargeable battery, also known as a secondary battery or accumulator battery, is a battery that can be recharged after discharge to reactivate its active materials and continue to be used. 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.

[0052] 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.

[0053] 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 pole piece characterized by: The electrode piece comprises a current collector and an active material layer arranged on at least one side surface of the current collector; the electrode piece is provided with at least one avoiding groove; and the avoiding groove penetrates the active material layer and the current collector respectively; When the electrode piece is wound into a core, the electrode piece has at least one corner segment and a straight segment arranged alternately; and the avoiding groove is arranged on the corner segment.

2. The pole piece of claim 1, wherein: Along the width direction of the electrode piece, the number of the avoiding grooves is at least two, and the avoiding grooves are arranged at two corner positions of the corner segment; and the avoiding grooves extend to the edge position of the electrode piece.

3. The pole piece of claim 1, wherein: Along the length direction of the electrode piece, the length of the avoiding groove is L2, and 0.2mm≤L2≤4mm is satisfied.

4. The pole piece according to any one of claims 1 to 3, characterized in that: The electrode piece is further provided with at least one liquid collector; the liquid collectors are arranged in sequence along the length direction of the electrode piece; and in the width direction of the electrode piece, the liquid collectors are arranged between two avoiding grooves.

5. The pole piece of claim 4, wherein: The liquid collector is a recess structure; the recess structure is arranged in a recessed manner from the surface of the active material layer to the surface of the current collector.

6. The pole piece of claim 5, wherein: The distance between two adjacent recess structures is d2, and 2mm≤d2≤10mm is satisfied; And / or, the depth of the recess structure is h1, and 60μm≤h1≤120μm is satisfied; And / or, the relationship between the depth h1 of the recess structure and the thickness h2 of the active material layer satisfies h1 7. The pole piece of claim 5, wherein: The electrode piece is further provided with a tab groove; the tab groove is arranged in the thickness direction of the active material layer; And the distance between the tab groove and the adjacent recess structure is d1, and 3mm≤d1≤5mm is satisfied.

8. An electric cell characterized by: The electrode piece comprises a first electrode piece, a second electrode piece and a separation film arranged between the first electrode piece and the second electrode piece; the first electrode piece, the separation film and the second electrode piece are wound in sequence to form a winding body; the outer surface of the winding body is sleeved with an aluminum plastic film; the first electrode piece and the second electrode piece are the electrode piece according to any one of claims 1 to 7.

9. The cell of claim 8, wherein: a length L of the avoidance groove in the second tab 02 a length L of the avoidance groove in the second tab 01 satisfies: L 01 > L 02 ; and the first tab is a positive tab; the second tab is a negative tab; And / or, the aluminum plastic film and the avoiding groove are provided with an adsorbing filling material; wherein the adsorbing filling material is graphene or carbon nanotube.

10. A secondary battery characterized by comprising: The battery cell comprises the battery cell according to claim 8 or 9.

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