Pole piece, battery cell and secondary battery

Abstract

The utility model belongs to the battery technical field, concretely relates to a kind of pole piece, electric core and secondary battery, wherein, the pole piece includes the main body section and tail section connected with each other along the length direction of pole piece;The tail section is equipped with gap part;Along the width direction of pole piece, the tail section has first side and second side;Along the length direction of pole piece, the tail section has third side and fourth side, and the fourth side is located the junction of the tail section with the main body section;The first side and / or the second side recessed setting towards pole piece interior, form the gap part, with one end of fourth side away;And main body section and / or tail section are equipped with metal base layer and active material layer connected to at least one side surface of metal base layer.The utility model can realize and form the hollow state with battery shell, cause pole piece structure not to contact with shell;Therefore it is advantageous to improve the energy density of electric core;And improve stability and security of use.

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] Bluetooth headsets are now widely used in daily life, and steel-cased button cell batteries are favored by manufacturers due to their higher energy density and safer characteristics. However, there are requirements for the radius (R) at the bottom of the casing when installing steel-cased button cells into the headset.

[0003] However, some existing steel-cased button cell designs prevent the electrodes of the bare cell from being bent by the radius of the casing by reducing the overall thickness of the bare cell, thus avoiding internal short circuits. However, this would severely reduce the cell's energy density (ED), and the space within the radius of the casing would be unusable. Utility Model Content

[0004] The purpose of this invention is to provide an electrode that addresses the shortcomings of existing technologies and solves the problem of low energy density in existing technologies.

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

[0006] An electrode includes a main body segment and a tail segment connected to each other along the length direction of the electrode; the tail segment has a notch; along the width direction of the electrode, the tail segment has a first side and a second side; along the length direction of the electrode, the tail segment has a third side and a fourth side, the fourth side being located at the junction of the tail segment and the main body segment; the end of the first side and / or the second side away from the fourth side is recessed toward the interior of the electrode to form the notch; and the main body segment and / or the tail segment have a metal base layer and an active material layer connected to at least one surface of the metal base layer.

[0007] Preferably, there are two notches, with the ends of the first and second sides away from the fourth side inclined in a straight line toward the inside of the electrode to form the notches.

[0008] Preferably, the tail section includes interconnected empty foil segments and connecting segments; the end of the connecting segment away from the empty foil segments is connected to the main body segment;

[0009] Furthermore, in the connecting segment, the projected area of ​​the active material layer toward the metal substrate is smaller than the area of ​​the metal substrate.

[0010] Preferably, in the connecting segment, along the width direction of the electrode, the relationship between the dimension M1 of the active material layer near the third side and the dimension M2 of the active material layer away from the third side satisfies: M2 > M1.

[0011] Preferably, the metal substrate in the empty foil segment and the active material layer in the connecting segment do not overlap in the electrode thickness direction.

[0012] This utility model also discloses a battery cell, including a first electrode, a second electrode, and a separator; the first electrode, the separator, and the second electrode are stacked in sequence and wound to form a wound body, and the notch portion forms an avoidance portion at the edge of the wound body in the length direction; an adhesive body is provided on the outer surface of the wound body in the circumferential direction;

[0013] Wherein, the first electrode and / or the second electrode are the electrodes.

[0014] Preferably, the relationship between the length L2 of the tail section, the length L1 of the main body section, and the diameter D of the winding body satisfies: L1 + L2 = 10 * D * K, where the value of K satisfies: 3.0 ≤ K ≤ 6.0.

[0015] This utility model also discloses a secondary battery, including a casing and the battery cell; the casing has an inner cavity for placement; the casing has an arc-shaped angle on the inner side facing the avoidance portion in the winding body; the notch is located on the inner side of the arc-shaped angle.

[0016] Preferably, the relationship between the radius R of the circle containing the arc angle, the length L2 of the tail segment, and the length L1 of the main segment satisfies: L2 / L1=m*R; where the value of m satisfies: 0<m≤3.5.

[0017] Preferably, an active filler material is provided between the notch and the arc-shaped angle.

[0018] The beneficial effects of this utility model are that, by adding a notch to the tail section, the thickness of the notch at the location of the electrode sheet when it is used in the battery cell is effectively reduced, thereby achieving a hollow state between the notch and the battery casing, so that the electrode sheet structure does not contact the casing; thus avoiding the electrode sheet structure being bent and causing an internal short circuit; therefore, it is beneficial to improve the energy density of the battery cell; and improve the stability and safety of use. Attached Figure Description

[0019] 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.

[0020] Figure 1This is a top view of an electrode sheet according to an embodiment of the present invention;

[0021] Figure 2 This is a front view of an electrode sheet according to an embodiment of the present invention;

[0022] Figure 3 This is a top view of an electrode sheet according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the battery cell in its unfolded state according to an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of the casing of a secondary battery according to an embodiment of the present invention.

[0026] In the diagram: 101-Main body segment; 102-Tail segment; 103-Notch section; 104-Empty foil segment; 105-Connecting segment; 11-Metal base layer; 12-Active material layer; 200-First electrode; 300-Second electrode; 400-Separating membrane; 500-Wound body; 600-Adhesive body; 700-Shell; 701-Curved angle; 702-Placement cavity; A-Width direction. Detailed Implementation

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] like Figure 1 and 2 As shown, in one embodiment of this utility model, the electrode includes a main body segment 101 and a tail segment 102 connected to each other; the tail segment 102 is provided with a notch 103; along the width direction (direction A) of the electrode, the tail segment 102 has a first side 105 and a second side 106; along the length direction (direction B) of the electrode, the tail segment 102 has a third side 108 and a fourth side 109, the fourth side 109 being located at the junction of the tail segment 102 and the main body segment 101; the end of the first side 105 and / or the second side 106 away from the fourth side 109 is recessed toward the interior of the electrode to form the notch 103; and the main body segment 101 and / or the tail segment 102 are provided with a metal base layer 11 and an active material layer 12 connected to at least one side surface of the metal base layer 11.

[0034] The technical solution of this utility model is to add a notch to the tail section to effectively reduce the thickness of the electrode at the location of the notch when it is used in the battery cell, thereby achieving a hollow state between the notch and the battery casing, so that the electrode structure does not contact the casing; thus avoiding the electrode structure being bent and causing internal short circuit; therefore, it is beneficial to improve the ED (energy density) of the battery cell; and improve the stability and safety of use.

[0035] Specifically, in some implementations, such as Figure 1 and 3As shown, there are two notches 103, symmetrically arranged on both sides of the tail section 102. The relationship between the depth N1 of the notch 103 away from the main body section 101 and the depth N2 of the notch 103 away from the main body section 101 satisfies: N1 > N2, to form a (regular or irregular) arc-shaped notch, a straight notch, or a curved notch. Specifically, the notch 103 is formed by a straight incline of the end of the first side 105 and the second side 106 away from the fourth side 109 towards the inside of the electrode, thus forming a straight notch. That is, the inner bottom of the notch 103 has an inclined surface; the depth of the notch 103 corresponding to the position of the inclined surface increases sequentially from the tail section 102 towards the main body section 101, so that the top position forms a hollow state with the battery casing, causing the electrode structure to not contact the casing; thereby avoiding the electrode structure being bent and causing an internal short circuit; thus, it is beneficial to ensure the ED (energy density) of the cell; and improve the stability and safety of use.

[0036] Specifically, in some implementations, such as Figure 1 , 2 As shown in Figure 3, the tail section 102 includes an interconnected empty foil segment 104 and a connecting segment 105; the side of the connecting segment 105 away from the empty foil segment 104 is connected to the main body section 101; and in the connecting segment 105, the projected area of ​​the active material layer 12 toward the metal substrate 11 is smaller than the area of ​​that position in the metal substrate 11; the metal substrate 11 in the empty foil segment 104 and the active material layer 12 in the connecting segment 105 do not overlap in the electrode thickness direction. That is, in the empty foil segment 104, the side surface of the metal substrate 11 is not provided with the active material layer 12. In other words, an assembly gap is provided between one end of the active material layer 12 in the width direction and one end of the metal substrate 11 in the width direction; that is, this structure uses the assembly gap to avoid damage to the active material layer 12 when the metal substrate 11 at the connecting segment 105 deforms, thereby improving the safety and stability of use and ensuring its ED (energy density value). In addition, by providing only a metal base layer 11 (without an active material layer 12) at the empty foil segment 104, the use of the active material layer 12 is reduced, and the ED (energy density value) of its use can be ensured; at the same time, the processing of the notch can be made convenient.

[0037] Specifically, in some implementations, such as Figure 3As shown, in the connecting segment 105, along the width direction of the electrode, the relationship between the dimension M1 of the active material layer 12 near the third side 108 and the dimension M2 of the active material layer 12 away from the third side 108 satisfies: M2 > M1. This structure, by gradually reducing the width of the active material layer 12 in the direction from the connecting segment 105 to the main body segment 101, ensures the usable ED (energy density value); it also facilitates the processing of the notch; furthermore, it facilitates the formation of a hollow state between the top position and the battery casing, resulting in the electrode structure not contacting the casing.

[0038] This utility model also proposes a battery cell, such as Figure 4 and 5 As shown, the battery cell includes a first electrode 200, a second electrode 300, and a separator 400; the first electrode 200, the separator 400, and the second electrode 300 are stacked sequentially and wound to form a wound body 500; a notch 103 forms a clearance portion at the edge of the wound body 500 in the length direction; an adhesive 600 is provided around the outer surface of the wound body 500 in the circumferential direction; wherein, the first electrode 200 and / or the second electrode 300 are electrodes. The specific structure of the electrode is as described in the above embodiments. Since this battery cell 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. The adhesive 600 is green adhesive; the first electrode 200 and the second electrode 300 are both electrodes; and the shapes of the first electrode 200, the second electrode 300, and the separator 400 correspond to each other (are consistent). Furthermore, the first electrode 200 is one type of positive and negative electrode; the second electrode 300 is another type of positive and negative electrode.

[0039] Specifically, in some implementations, such as Figure 1 , 2 As shown in Figure 5, the relationship between the length L2 of the tail section 102, the length L1 of the main body section 101, and the diameter D of the winding body 500 satisfies: L1 + L2 = 10 * D * K, where the value of K satisfies: 3.0 ≤ K ≤ 6.0. It can be selected as L1 + L2 = 10 * D * 4.0. This structure, through appropriate dimensional design of the tail section 102, the main body section 101, and the winding body 500, fully utilizes the space in the R-corner portion of the casing, thereby facilitating the formation of a hollowed-out state between the top position and the battery casing, resulting in the electrode structure not contacting the casing.

[0040] Furthermore, 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 positive current collector includes a positive coating area and a positive electrode tab connected to the positive coating area, 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 negative current collector includes a negative coating area and a negative electrode tab connected to the negative coating area, 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 400 can be made of PP (polypropylene) or PE (polyethylene), etc.

[0041] This utility model also proposes a secondary battery, which includes a battery cell and a casing 700. The battery cell is a wound body 500. The casing 700 has an inner cavity 702. The casing 700 has an arc-shaped angle 701 on the inner side facing the avoidance portion in the wound body 500. A notch 103 is provided on the inner side of the arc-shaped angle 701. 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. Among them, such as Figure 6 As shown, the housing 700 has an inner cavity 702, and an arc-shaped angle 701 is provided at the inner bottom and inner top of the inner cavity 702.

[0042] Specifically, in some implementations, such as Figure 1 , 2 As shown in Figure 6, the relationship between the radius R of the circle containing the arc angle 701, the length L2 of the tail segment 102, and the length L1 of the main segment 101 satisfies: L2 / L1=m*R; where the value of m satisfies: 0<m≤3.5. Possible values ​​are L2 / L1=m*0.1; L2 / L1=m*0.2; L2 / L1=m*0.3;

[0043] L2 / L1 = m * 0.4; L2 / L1 = m * 0.5; L2 / L1 = m * 0.6; L2 / L1 = m * 0.7; L2 / L1 = m * 0.8; L2 / L1 = m * 0.9; L2 / L1 = m * 1.4; L2 / L1 = m * 2.5; L2 / L1 = m * 3.3; L2 / L1 = m * 3.5, etc. In other words, m is a control factor, ranging from 0 to 3.5. The larger the radius of the circle containing the corresponding R-angle of the casing, the longer the corresponding L2 region is adjusted accordingly. This facilitates achieving a hollowed-out state between the top position and the battery casing, preventing the electrode structure from contacting the casing.

[0044] Specifically, in some embodiments, (not shown in the figure) an active filler material is provided between the notch 103 and the arc angle 701. The active filler material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. Alternatively, the active filler material can be carbon or silicon, etc. This structure uses an active material to fill the gap in the S region between the notch 103 and the arc angle 701, thereby significantly improving the ED (energy density) of the steel-cased button cell.

[0045] 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.

[0046] The ED of the bare cell is measured to see if it is improved, and the CT is used to determine whether the cell is pressed against the electrode. If so, it is judged as NG / OK.

[0047] Example 1

[0048] Take a housing 700 with a radius of 0.3mm corresponding to the R angle; the housing 700 is a steel-cased button cell with a diameter of 10.9mm and a thickness of 4.8mm, the cathode plate width is 3.1mm and the anode plate width is 3.6mm; the length of L2 is 240mm; the length of L1 is 240mm; and L2 / L1=1; m=3.3.

[0049] Example 2

[0050] Example 2 differs from Example 1 in that: the length of L2 is 280mm; the length of L1 is 200mm; and L2 / L1 = 0.7; m = 2.4.

[0051] Example 3

[0052] Example 3 differs from Example 1 in that: the shell with a radius of 0.4 mm corresponding to the R angle is 700; m = 2.5.

[0053] Example 4

[0054] Example 4 differs from Example 1 in that: the shell with radius 700 corresponding to the R angle is 0.4mm; the length of L2 is 400mm; the length of L1 is 80mm; and L2 / L1 = 0.2; m = 0.5.

[0055] Example 5

[0056] Example 5 differs from Example 1 in that: the shell 700 with a radius of 0.5mm corresponding to the R angle is selected; the length of L2 is 440mm; the length of L1 is 40mm; and L2 / L1 = 0.1; m = 0.2.

[0057] Example 6

[0058] Example 6 differs from Example 1 in that: the shell 700 with a radius of 0.5mm corresponding to the R angle is selected; the length of L2 is 280mm; the length of L1 is 200mm; and L2 / L1=0.7; m=1.4.

[0059] Example 7

[0060] Example 7 differs from Example 1 in that: the shell 700 with a radius of 0.5mm corresponding to the R angle is selected; the length of L2 is 360mm; the length of L1 is 120mm; and L2 / L1 = 0.3; m = 0.7.

[0061] Example 8

[0062] Example 8 differs from Example 1 in that: the shell 700 with a radius of 0.6 mm corresponding to the R angle is selected; the length of L2 is 320 mm; the length of L1 is 160 mm; and L2 / L1 = 0.5; m = 0.8.

[0063] Comparative Example 1

[0064] The difference between Comparative Example 1 and Example 1 is that: the shell 700 with a radius of 0.7 mm corresponding to the R angle is selected; the length of L2 is 320 mm; the length of L1 is 160 mm; and L2 / L1 = 0.5; m = 0.7.

[0065] Comparative Example 2

[0066] The difference between Comparative Example 2 and Example 1 is that: the shell 700 with a radius of 0.8 mm corresponding to the R angle is selected; the length of L2 is 320 mm; the length of L1 is 160 mm; and L2 / L1 = 0.5; m = 0.6.

[0067] Comparative Example 3

[0068] The difference between Comparative Example 3 and Example 1 is that: the shell 700 with a radius of 0.8 mm corresponding to the R angle is selected; the length of L2 is 480 mm; the length of L1 is 0 mm; and L2 / L1 = 0; m = 0.

[0069] ED value and CT scan data table

[0070]

[0071]

[0072] In summary, the radius of the circle corresponding to the R-angle of the casing is in the range of 0.3mm to 0.6mm, and the larger the value, the longer the corresponding L2 region is adjusted accordingly, so that 0 < m ≤ 3.5. This can create a gap between the corner of the cell and the R-angle of the casing, avoiding the phenomenon of the electrode plates at the upper and lower corners of the cell being bent by the casing and causing internal short circuits. At the same time, it can also ensure energy density and improve the stability and safety of use.

[0073] 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.

[0074] 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. An electrode sheet, characterized in that: The electrode comprises a main body segment and a tail segment connected to each other along the length of the electrode; the tail segment has a notch; along the width of the electrode, the tail segment has a first side and a second side; along the length of the electrode, the tail segment has a third side and a fourth side, the fourth side being located at the junction of the tail segment and the main body segment; the end of the first side and / or the second side away from the fourth side is recessed toward the interior of the electrode to form the notch; and the main body segment and / or the tail segment are provided with a metal base layer and an active material layer connected to at least one surface of the metal base layer.

2. The electrode sheet according to claim 1, characterized in that: The notch is provided in two parts, with the ends of the first and second sides away from the fourth side inclined in a straight line toward the inside of the electrode to form the notch.

3. The electrode sheet according to claim 1, characterized in that: The tail section includes interconnected empty foil segments and connecting segments; the end of the connecting segment away from the empty foil segments is connected to the main body segment; Furthermore, in the connecting segment, the projected area of ​​the active material layer toward the metal substrate is smaller than the area of ​​the metal substrate.

4. The electrode sheet according to claim 3, characterized in that: In the connecting segment, along the width direction of the electrode, the relationship between the dimension M1 of the active material layer near the third side and the dimension M2 of the active material layer away from the third side satisfies: M2 > M1.

5. The electrode sheet according to claim 3, characterized in that: The metal substrate in the empty foil segment and the active material layer in the connecting segment do not overlap in the electrode thickness direction.

6. A battery cell, characterized in that: It includes a first electrode, a second electrode, and a separator; the first electrode, the separator, and the second electrode are stacked in sequence and wound to form a wound body, and the notch portion forms a clearance portion at the edge of the wound body in the length direction; an adhesive is provided on the outer surface of the wound body in the circumferential direction; Wherein, the first electrode and / or the second electrode are any one of the electrode sheets of claims 1 to 5 above.

7. The battery cell according to claim 6, characterized in that: The relationship between the length L2 of the tail section, the length L1 of the main body section, and the diameter D of the winding body satisfies: L1 + L2 = 10 * D * K, where the value of K satisfies: 3.0 ≤ K ≤ 6.

0.

8. A secondary battery, characterized in that: The device includes a housing and the battery cell as described in claim 6 or 7; the housing has an inner cavity for placement; the housing has an arc-shaped angle on the inner side facing the avoidance portion in the winding body; the notch is located on the inner side of the arc-shaped angle.

9. The secondary battery according to claim 8, characterized in that: The relationship between the radius R of the circle containing the arc angle, the length L2 of the tail segment, and the length L1 of the main segment satisfies: L2 / L1=m*R; where the value of m satisfies: 0<m≤3.

5.

10. The secondary battery according to claim 8, characterized in that: An active filler material is provided between the notch and the arc-shaped angle.

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