Secondary battery, battery pack, and electronic device
By setting a recessed structure on the positive electrode sheet and negative electrode sheet of the secondary battery, the difficulty and expansion of the electrolyte infiltration are solved, better electrolyte infiltration and stress release are achieved, and the service life of the battery is extended.
Patent Information
- Application Number
- CN202421082735.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-16
- Publication Date
- 2025-03-28
- Estimated Expiration
- 2034-05-16
AI Technical Summary
Existing secondary batteries have difficulties in electrolyte infiltration and are prone to expand later in the cycle, resulting in concentrated circle stress in the pole sheet and large polarization.
A recessed structure is provided on at least one of the positive electrode sheet and the negative electrode sheet to help the electrolyte soak better and release stress, avoid stress concentration.
Through the design of the recessed structure, the infiltration of the electrolyte is improved, the expansion of the secondary battery is alleviated, stress concentration is reduced, and the service life of the battery is improved.
Smart Images
Figure CN222690727U_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the utility model relate to a secondary battery, a battery pack and an electronic device. Background Art
[0002] In the field of new energy power batteries, secondary batteries refer to rechargeable batteries, also called renewable batteries or storage batteries. Unlike primary batteries, secondary batteries can be charged and discharged multiple times through reverse charging for reuse. Secondary batteries generally include electrode assemblies, housings, cover plates, etc. Cylindrical batteries refer to cylindrical rolled core batteries, which include housings and electrode assemblies. The electrode assemblies include positive electrode sheets, negative electrode sheets, and separators located between the positive electrode sheets and the negative electrode sheets. These positive electrode sheets, negative electrode sheets, and separators are stacked on each other and wound into electrode assemblies, which are then encapsulated in housings. Utility Model Content
[0003] In view of the problems existing in the related art, the purpose of the present invention is to provide a secondary battery, a battery pack and an electronic device, so as to at least improve the electrolyte infiltration of the secondary battery and alleviate the expansion of the secondary battery.
[0004] To achieve the above-mentioned objectives, the utility model provides a secondary battery, comprising: a positive electrode sheet, a first separator, a negative electrode sheet and a second separator, which are stacked in sequence and wound to form an electrode assembly, and the surface of the active material layer of at least one of the positive electrode sheet and the negative electrode sheet facing and / or facing away from the other includes at least one recessed structure toward the inside of the active material layer.
[0005] In some embodiments, at least one recessed structure is located in the middle circle portion of the positive electrode sheet and / or the negative electrode sheet. Both the positive electrode sheet and the negative electrode sheet have a sheet length along the winding direction and a starting edge located at the innermost circle of the winding. Along the direction extending from the starting edge to the outer circle, the middle circle portion of the positive electrode sheet and the negative electrode sheet is 1 / 4 to 2 / 3 of the length of the electrode sheet.
[0006] In some embodiments, the at least one recessed structure has a recessed depth of 0.5 μm to 5 μm.
[0007] In some embodiments, when viewed in a direction perpendicular to the surface of the active material layer, at least one of the recessed structures is in a dot shape, a straight line shape, or a curved stripe shape.
[0008] In some embodiments, the spacings between the multiple recessed structures on the positive electrode sheet or the negative electrode sheet are the same or substantially the same.
[0009] In some embodiments, at least one recessed structure is a laser cleaning mark.
[0010] In some embodiments, the secondary battery is a cylindrical battery, and the ratio of the height to the diameter is in the range of 1.7-3.3.
[0011] In some embodiments, the negative electrode plate includes at least one recessed structure, and the positive electrode plate does not include a recessed structure.
[0012] An embodiment of the present application further provides a battery pack, comprising any one of the secondary batteries described above.
[0013] An embodiment of the present application further provides an electronic device, comprising at least one of the secondary battery and the battery pack described above.
[0014] The beneficial technical effects of the utility model are:
[0015] The embodiments of the present application provide a recessed structure on at least one of the positive electrode sheet and the negative electrode sheet, which helps the electrolyte to better infiltrate the positive electrode sheet and the negative electrode sheet, and the recessed structure can release the stress on the positive electrode sheet and / or the negative electrode sheet, avoiding stress concentration and alleviating the expansion of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0017] Figure 1 A schematic diagram showing a case where the electronic device according to an embodiment of the present application is a vehicle.
[0018] Figure 2 A perspective view of a secondary battery according to an embodiment of the present application is shown.
[0019] Figure 3 A cross-sectional view of a secondary battery according to an embodiment of the present application is shown.
[0020] Figure 4 A perspective view of a secondary battery according to an embodiment of the present application is shown.
[0021] Figure 5 and Figures 7 to 11 A front view of an unfolded positive electrode sheet or a negative electrode sheet is shown.
[0022] Figure 6 A bottom view of an unfolded positive electrode sheet or a negative electrode sheet is shown. DETAILED DESCRIPTION
[0023] In order to better understand the spirit of the embodiments of the present application, some preferred embodiments of the present application are further described below.
[0024] The embodiments of the present application will be described in detail below. In the full text of the present application specification, the same or similar components and components with the same or similar functions are represented by similar reference numerals. The embodiments of the accompanying drawings described herein are illustrative, graphical, and are used to provide a basic understanding of the present application. The embodiments of the present application should not be interpreted as limiting the present application.
[0025] As used herein, the terms "substantially," "substantially," "essentially," and "about" are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms may refer to instances where the event or circumstance occurred precisely as well as instances where the event or circumstance occurred very approximately.
[0026] In this specification, unless otherwise specified or limited, relative terms such as "central", "longitudinal", "lateral", "front", "rear", "right", "left", "inner", "outer", "lower", "higher", "horizontal", "vertical", "above", "below", "above", "below", "top", "bottom" and their derivative terms (such as "horizontally", "downwardly", "upwardly", etc.) should be interpreted as referring to the directions described in the discussion or depicted in the drawings. These relative terms are only used for convenience of description and do not require that the present application be constructed or operated in a specific direction.
[0027] For convenience of description, “first”, “second”, “third”, etc. may be used herein to distinguish different components in one figure or a series of figures. “First”, “second”, “third”, etc. are not intended to describe the corresponding components.
[0028] It is difficult for the electrolyte of current secondary batteries to infiltrate the pole piece, and the pole piece will expand in the later stage of the secondary battery cycle, so the stress is concentrated at the middle circle of the pole piece and the polarization is large.
[0029] For the convenience of description, the following embodiments are described by taking the electronic device as a vehicle 1000 as an example.
[0030] See also Figure 1 The vehicle 1000 is provided with a battery pack 1002 inside, and the battery pack 1002 can be provided at the bottom, head, or tail of the vehicle body 1001. The battery pack 1002 can be used for powering the vehicle 1000, for example, the battery pack 1002 can be used as an operating power source for the vehicle 1000.
[0031] Figure 21 shows a perspective view of a secondary battery 100 according to an embodiment of the present application, Figure 3 1 shows a cross-sectional view of a secondary battery 100 according to an embodiment of the present application, Figure 4 The electrode assembly 120 according to an embodiment of the present application is shown. The electrode assembly 120 is mainly formed by winding or stacking a positive electrode sheet 10 and a negative electrode sheet 12, and a separator is usually provided between the positive electrode sheet 10 and the negative electrode sheet 12. The positive electrode sheet 10 includes a positive current collector and a positive active material layer, and the positive active material layer is coated on the surface of the positive current collector; the positive current collector includes a positive electrode coating area and a positive electrode ear connected to the positive electrode coating area, the positive electrode coating area is coated with the positive electrode active material layer, and the positive electrode ear is not coated with the positive electrode active material layer. The negative electrode sheet 12 includes a negative electrode collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode collector; the negative electrode collector includes a negative electrode coating area and a negative electrode ear connected to the negative electrode coating area, the negative electrode coating area is coated with the negative electrode active material layer, and the negative electrode ear is not coated with the negative electrode active material layer. Taking lithium-ion batteries as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material layer includes the positive electrode active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide. The material of the negative electrode current collector can be copper, and the negative electrode active material layer includes the negative electrode active material, which can be carbon or silicon. The material of the diaphragm can be PP or PE. In order to protect and insulate the electrode assembly 120, an insulating film can also be coated on the outside of the electrode assembly 120, and the insulating film can be synthesized from PP, PE, PET, PVC or other high molecular polymer materials.
[0032] In an example of the secondary battery of the utility model, the electrode assembly 120 is sealed and installed in the housing 200. Along the height direction of the secondary battery 100, the electrode assembly 120 is arranged between the end wall 111 and the rolling groove 113, and the rolling groove 113 can limit the axial movement of the electrode assembly 120 between the end wall 111 and the rolling groove 113. The electrode assembly 120 is respectively provided with a first pole ear and a second pole ear at both ends of the height direction (i.e., the Y-axis direction) of the secondary battery 100, and the polarities of the first pole ear and the second pole ear are opposite, wherein the first pole ear faces the opening side, and the first pole ear is a negative pole ear. It should be noted that in other embodiments, the first pole ear can also be a positive pole ear, and the second pole ear can be a negative pole ear.
[0033] The embodiment of the present application provides a secondary battery 100, which includes a positive electrode sheet 10, a first separator, a negative electrode sheet 12, and a second separator, which are sequentially stacked and wound to form an electrode assembly 120. Figure 5 and Figures 7 to 11 The front view of the unfolded positive electrode sheet 10 or negative electrode sheet 12 (observed perpendicularly to the active material layer surface S1, S2) is shown. Figure 6The bottom view of the unfolded positive electrode sheet 10 or negative electrode sheet 12 is shown [observed parallel to the active material layer surface S1, S2 and parallel to the width direction of the electrode sheet (Y-axis direction)], and the active material layer surface S1, S2 facing and / or facing away from the other of at least one of the positive electrode sheet 10 and the negative electrode sheet 12 includes at least one recessed structure 20 facing the inside of the active material layer. The positive electrode sheet 10 and the negative electrode sheet 12 both include a current collector and an active material layer located on both sides of the current collector. The at least one recessed structure 20 exists in the active material layer on at least one side of the current collector of at least one of the positive electrode sheet 10 and the negative electrode sheet 12. The thickness of the active material layer at the location of the recessed structure 20 is different from the thickness of the active material layer at other locations, and the area where the recessed structure 20 is located constitutes a thinning area of the electrode sheet. The secondary battery 100 also includes an electrolyte, and the electrolyte infiltrates the positive electrode sheet 10, the negative electrode sheet 12, and the first separator and the second separator. The embodiment of the present application provides a recessed structure 20 on at least one of the positive electrode sheet 10 and the negative electrode sheet 12, which helps the electrolyte to better infiltrate the positive electrode sheet 10 and the negative electrode sheet 12, and the recessed structure 20 can release the stress on the positive electrode sheet 10 and / or the negative electrode sheet 12. In particular, for cylindrical batteries, the stress is more concentrated. Therefore, the recessed setting avoids stress concentration and alleviates the expansion of the secondary battery 100.
[0034] In some preferred embodiments, the negative electrode sheet 12 includes at least one recessed structure 20. In some embodiments, the positive electrode sheet 10 does not include the recessed structure 20. That is, the recessed structure 20 is preferably located on the negative electrode sheet 12, because the negative electrode sheet 12 is wound outside the positive electrode sheet 10, and if the secondary battery 100 expands, the stress on the negative electrode sheet 12 is greater than that on the positive electrode sheet 10.
[0035] In some embodiments, at least one recessed structure 20 is located in the middle circle portion of the positive electrode sheet 10 and / or the negative electrode sheet 12, and the positive electrode sheet 10 and the negative electrode sheet 12 both have a sheet length L along the winding direction, and a starting edge 40 (winding starting position) located at the innermost circle of the winding, and along the direction extending from the starting edge 40 to the outer circle, the middle circle portion of the positive electrode sheet 10 and the negative electrode sheet 12 is 1 / 4 to 2 / 3 of the sheet length L (see Figures 2 to 6 Due to the presence of the recessed structure 20, the thickness of at least one of the positive electrode sheet 10 and the negative electrode sheet 12 at the middle circle position is intermittently different, and the recessed structure 20 can release the stress at the middle circle position of the electrode sheet where stress concentration is prone to occur.
[0036] In some embodiments, the recess depth of at least one recess structure 20 [along the thickness direction of the pole piece (ie, Z-axis direction)] is 0.5 μm to 5 μm, and there is a corresponding ratio between the recess depth of the recess structure 20 and the thickness of the active material layer.
[0037] See also Figure 2 , Figure 4 , Figure 6 and Figure 7 In some embodiments, when viewed along a direction perpendicular to the active material layer surfaces S1 and S2, at least one recessed structure 20 is in a linear shape, which is more conducive to the infiltration of the electrolyte.
[0038] In some embodiments, when viewed along a direction perpendicular to the main surfaces S1 and S2 , at least one recessed structure 20 is in a dot shape, and the recessed structures 20 in the dot shape are more evenly distributed.
[0039] See also Figure 5 and Figure 8 In some embodiments, when viewed in a direction perpendicular to the main surfaces S1 and S2, at least one recessed structure 20 is in the shape of a curved stripe, which is more conducive to releasing stress on the pole piece.
[0040] In some embodiments, the spacing between the multiple recessed structures 20 on the positive electrode sheet 10 or the negative electrode sheet 12 may be the same (eg Figures 2 to 5 , Figure 7 and Figure 8 The embodiment shown) or substantially the same (e.g. Figure 6 The embodiment shown), wherein substantially the same means that the difference values are within a range of 10%.
[0041] In some embodiments, at least one recessed structure 20 is a laser cleaning trace. Figures 2 to 6 In the embodiment, laser cleaning starts from the 1 / 4L position and ends at the 2 / 3L position.
[0042] In some embodiments, the secondary battery 100 is a 4680 cylindrical battery, and the height (eg Figure 3 As shown, the ratio of the distance from the end wall 111 to the cover plate 130 to the diameter (outer diameter) is in the range of 1.7-3.3, for example, the height is 80 mm and the diameter is 46 mm; another example is the height is 15 mm and the diameter is 46 mm. In some embodiments, the secondary battery 100 is a 4680 cylindrical battery.
[0043] See also Figure 2 , Figures 4 to 6 In some embodiments, the recessed structure 20 extends through the entire width of the active material layer of the positive electrode sheet 10 and / or the negative electrode sheet 12. Figure 7 and Figure 8 In some embodiments, the recessed structure 20 runs through the entire length of the active material layer of the positive electrode sheet 10 and / or the negative electrode sheet 12 .
[0044] The embodiment of the present application further provides a battery pack 1002 including any one of the secondary batteries 100 described above.
[0045] The embodiment of the present application further provides an electronic device 1000 , comprising at least one of the secondary battery 100 and the battery pack 1002 described above.
[0046] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.
Claims
1. A secondary battery, characterized in that: include: The positive electrode sheet, the first separator, the negative electrode sheet and the second separator are stacked in sequence and then wound to form an electrode assembly. The surface of the active material layer of at least one of the positive electrode sheet and the negative electrode sheet facing and / or facing away from the other includes at least one recessed structure toward the inside of the active material layer.
2. The secondary battery according to claim 1, characterized in that: The at least one recessed structure is located in the middle circle portion of the positive electrode sheet and / or the negative electrode sheet. Both the positive electrode sheet and the negative electrode sheet have a sheet length along the winding direction and a starting edge located at the innermost circle of the winding. Along the direction extending from the starting edge to the outer circle, the middle circle portion of the positive electrode sheet and the negative electrode sheet is 1 / 4 to 2 / 3 of the length of the electrode sheet.
3. The secondary battery according to claim 1, characterized in that: The at least one recessed structure has a recessed depth of 0.5 μm to 5 μm.
4. The secondary battery according to claim 1, characterized in that: Along a direction perpendicular to the surface of the active material layer, the at least one concave structure is in a dot shape, a straight line shape, or a curved stripe shape.
5. The secondary battery according to claim 1 or 4, characterized in that: The spacings between the multiple recessed structures on the positive electrode sheet or the negative electrode sheet are the same or substantially the same.
6. The secondary battery according to claim 1, characterized in that: The at least one recessed structure is a laser cleaning trace.
7. The secondary battery according to claim 1, characterized in that: The secondary battery is a cylindrical battery, and the ratio of its height to its diameter is in the range of 1.7-3.
3.
8. The secondary battery according to claim 1, characterized in that: The negative electrode plate includes the at least one recessed structure, and the positive electrode plate does not include the recessed structure.
9. A battery pack, characterized in that: A secondary battery comprising any one of claims 1 to 8.
10. An electronic device, characterized in that: The invention comprises at least one of the secondary battery according to any one of claims 1 to 8 and the battery pack according to claim 9.