Negative pole piece and secondary battery
By designing the hole structure on the surface of the active layer of the negative electrode sheet, the problem of insufficient capacity and circulation performance of the lithium-ion battery is solved, and higher discharge capacity and circulation performance are achieved, while ensuring the processing quality and safety of the electrode sheet.
Patent Information
- Application Number
- CN202422271383.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-18
- Publication Date
- 2025-08-26
- Estimated Expiration
- 2034-09-18
AI Technical Summary
Traditional negative electrode sheets are difficult to achieve high capacity and good cycle performance in lithium-ion batteries at the same time, especially due to the degradation of battery performance caused by volume expansion during charging and discharging of silicon materials.
A plurality of first holes are opened on the surface of the active layer of the negative electrode sheet. The holes are designed to gradually narrow radially near the direction of the metal current collector, with a depth of 1 μm to 150 μm, a porosity of 10% to 60%. A second hole is provided on the metal current collector, and the holes are designed to improve the electrolyte wetting ability and lithium ion shuttle speed.
Through the hole design, the wetting property of the electrolyte and the shuttle speed of lithium ions are improved, and the diffusion distance is reduced, thereby improving the discharge capacity and cycling performance of the battery, while ensuring the processing quality and safety performance of the electrode sheet.
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Figure CN223273295U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a negative electrode plate and a secondary battery. Background Art
[0002] Lithium-ion batteries offer high energy efficiency and a long lifespan, holding them for broad application prospects. The development of industries such as electric vehicles, consumer electronics, and new energy storage systems is placing higher demands on the performance of lithium-ion batteries. The theoretical gram capacity of silicon anodes is approximately 10 times that of graphite anodes, enabling higher energy density. However, silicon material experiences nearly 300% volume expansion during charge and discharge, significantly impacting the battery's cycle life. This means that conventional anode electrodes make it difficult to achieve both high capacity and cycling performance in lithium-ion batteries. Utility Model Content
[0003] Based on this, it is necessary to provide a negative electrode plate, a secondary battery and an electrical device. The negative electrode plate of the present application can improve the discharge capacity and cycle performance of the battery.
[0004] In a first aspect, the present application provides a negative electrode plate, comprising a metal current collector and an active layer disposed on the surface of the metal current collector; a plurality of first holes are formed on the surface of the active layer away from the metal current collector.
[0005] In some embodiments, the radial width of the first hole gradually narrows in a direction approaching the metal current collector.
[0006] In some embodiments, the first holes have a pore size of 1 μm to 100 μm.
[0007] In some embodiments, the depth of the first holes is 1 μm to 150 μm.
[0008] In some embodiments, the first hole is a blind hole, and the depth of the first hole is 1 / 5 to 4 / 5 of the thickness of the active layer.
[0009] In some embodiments, the distance between two adjacent first holes is 50 μm to 500 μm.
[0010] In some embodiments, the plurality of first holes are distributed in a matrix.
[0011] In some embodiments, the metal current collector is provided with a second hole extending along the thickness direction thereof, the second hole is a blind hole, and the opening of the second hole is arranged toward the active layer.
[0012] In some embodiments, the second holes have a depth of 0.5 μm to 10 μm.
[0013] In some embodiments, the depth of the second hole is less than or equal to 2 / 3 of the thickness of the metal current collector.
[0014] In some embodiments, the porosity of the negative electrode sheet is 10% to 60%.
[0015] In a second aspect, the present application provides a secondary battery comprising the negative electrode sheet described in any one of the above items.
[0016] Due to the presence of the first hole in the active layer of the above-mentioned negative electrode plate, the wettability of the electrolyte and the shuttle speed of lithium ions can be improved, and the diffusion distance of lithium ions can be reduced, thereby improving the discharge capacity and cycle performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 A schematic structural diagram of a negative electrode sheet provided in one embodiment of the present application;
[0018] Figure 2 A schematic structural diagram of a negative electrode sheet provided in another embodiment of the present application;
[0019] Figure 3 This is a SEM image of the negative electrode sheet in Example 8 of the present application;
[0020] Figure 4 This is an SEM image of a single hole in the negative electrode plate in Example 8 of the present application;
[0021] Figure 5 This is an SEM image of the cross section of the negative electrode sheet in Example 8 of the present application.
[0022] Description of Reference Numerals
[0023] 10. Metal current collector; 20. Active layer; 30. First hole; 40. Second hole. DETAILED DESCRIPTION
[0024] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.
[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0026] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.
[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.
[0028] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.
[0029] Reference Figure 1 As shown, an embodiment of the present application provides a negative electrode plate, including a metal current collector 10 and an active layer 20 disposed on the surface of the metal current collector 10; a first hole 30 is opened on the surface of the active layer 20 away from the metal current collector 10.
[0030] The presence of the first holes 30 in the active layer 20 of the negative electrode sheet improves electrolyte wettability and lithium ion shuttle speed, reduces the diffusion distance of lithium ions, and thus improves the discharge capacity and cycle performance of the battery. It should be noted that the first holes 30 can be all through holes, all blind holes, or some through holes and some blind holes.
[0031] In some embodiments, the radial width of the first hole 30 gradually narrows as it approaches the metal current collector 10 .
[0032] In some embodiments, the first holes 30 have a diameter of 1 μm to 100 μm.
[0033] It is understood that the pore size of the first hole 30 refers to the maximum radial width of the first hole 30. Optionally, the pore size of the first hole 30 is 30 μm to 70 μm. Further, optionally, the pore size of the first hole 30 is 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, or 70 μm. Alternatively, the pore size of the first hole 30 may be within a range between any two of the aforementioned pore sizes.
[0034] In some embodiments, the depth of the first hole 30 is 1 μm to 150 μm.
[0035] It is understood that when the first hole 30 is a blind hole, the depth of the first hole 30 refers to the length from its opening to its bottom end. When the first hole 30 is a through hole, the depth of the first hole 30 is the length of the through hole. Optionally, the depth of the first hole 30 is 1μm, 2μm, 5μm, 10μm, 15μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, or 150μm. Alternatively, the depth of the first hole 30 may be within a range between any two of the above depths.
[0036] In some embodiments, the first hole 30 is a blind hole, and the depth of the first hole 30 is 1 / 5 to 4 / 5 of the thickness of the active layer 20 .
[0037] Optionally, the depth of the first hole 30 is 1 / 5, 1.2 / 5, 1.5 / 5, 1.8 / 5, 2 / 5, 2.2 / 5, 2.5 / 5, 2.8 / 5, 3 / 5, 3.2 / 5, 3.5 / 5, 3.8 / 5, or 4 / 5 of the thickness of the active layer 20. Alternatively, the ratio of the depth of the first hole 30 to the thickness of the active layer 20 may be within a range between any two of the above ratios.
[0038] It should be noted that, theoretically, the deeper the depth of the holes in the active layer 20 and the larger the pore size, the more conducive it is to the infiltration of the electrolyte, thereby improving the discharge capacity and cycle performance of the battery. It is understandable that the pore size and depth here refer to the average pore size and average depth of all the first holes 30. However, drilling too deep or the pore size is too large may cause severe squeezing of the powder inside the electrode, causing the powder in local areas to become loose and the adhesion to decrease, resulting in powder loss of the electrode, thereby affecting the subsequent processing and safety performance of the negative electrode, and further affecting the performance of the battery. Therefore, within the range of the depth and pore size of the above-mentioned first hole 30, while achieving better discharge capacity and cycle performance, it can also ensure the processing quality and safety performance of the negative electrode.
[0039] In some embodiments, the distance between two adjacent first holes 30 is 50 μm to 500 μm.
[0040] Optionally, the distance between two adjacent first holes 30 is 200 μm to 400 μm. Further, optionally, the distance between two adjacent first holes 30 is 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, 320 μm, 340 μm, 360 μm, 380 μm, or 400 μm. Alternatively, the distance between two adjacent first holes 30 may be within a range between any two of the above distances.
[0041] In some embodiments, the plurality of first holes 30 are distributed in a matrix. It is understood that the plurality of first holes 30 being distributed in a matrix means that the plurality of first holes 30 can be distributed in rows and columns or in concentric circles.
[0042] Reference Figure 2 As shown, in some embodiments, the metal current collector 10 is provided with a second hole 40 extending along the thickness direction thereof. The second hole 40 is a blind hole, and the opening of the second hole 40 is arranged toward the active layer 20 .
[0043] In some embodiments, the depth of the second hole 40 is 0.5 μm to 10 μm.
[0044] Optionally, the depth of the second hole 40 is 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm or 10 μm. Alternatively, the depth of the second hole 40 may be within a range between any two of the above depths.
[0045] In some embodiments, the depth of the second holes 40 is less than or equal to ⅔ of the thickness of the metal current collector 10 .
[0046] Optionally, the ratio of the depth of the second hole 40 to the thickness of the metal current collector 10 is 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2, or 2 / 3. Alternatively, the ratio of the depth of the second hole 40 to the thickness of the metal current collector 10 may also be within a range between any two of the above ratios.
[0047] In some embodiments, the porosity of the negative electrode sheet is 10% to 60%.
[0048] Optionally, the porosity of the negative electrode sheet is 25% to 50%. Further, optionally, the porosity of the negative electrode sheet is 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, or 50%. Alternatively, the porosity of the negative electrode sheet may be within a range between any two of the above porosities.
[0049] In some embodiments, the first hole 30 and / or the second hole 40 are prepared by laser drilling.
[0050] In some embodiments, the material of the active layer 20 includes an active material, a conductive agent, a binder, and a dispersant.
[0051] In some embodiments, the active material includes a silicon material, a tin material, and a graphite material.
[0052] In some embodiments, the silicon material includes at least one of pre-lithiated silicon, pre-lithiated silicon-oxygen, silicon nanoparticles, silicon alloys, and silicon-oxygen composite materials.
[0053] In some embodiments, the graphite material includes at least one of natural graphite, artificial graphite, soft carbon, and hard carbon.
[0054] In some embodiments, the conductive agent includes at least one of conductive carbon black SP, multi-walled carbon nanotubes, single-walled carbon nanotubes, graphene, acetylene black, and Ketjen black.
[0055] In some embodiments, the binder includes at least one of styrene-butadiene rubber, sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, and polyacrylic acid resin.
[0056] In some embodiments, the dispersant includes at least one of polyvinyl pyrrolidone, N-methyl pyrrolidone, and carboxymethyl cellulose.
[0057] In some embodiments, the mass ratio of the active material, the conductive agent, the dispersant, and the binder is (80-95):(0.5-2.5):(0-2.5):(2-10).
[0058] Another embodiment of the present application provides a secondary battery, comprising any one of the above-mentioned negative electrode sheets.
[0059] The following are specific embodiments
[0060] Comparative Example 1
[0061] Preparation method of negative electrode sheet:
[0062] Silicon flakes are made from solar cell silicon waste. The active material is then mixed with carbon black powder, CNTs, sodium carboxymethyl cellulose, and styrene-butadiene rubber (SBR) and stirred to create a negative electrode slurry. The active material content is 85%, the carbon black content is 4%, the CNT content is 3.5%, the dispersant sodium carboxymethyl cellulose content is 2.5%, and the SBR content is 5%. The negative electrode slurry is applied to both sides of copper foil to form a negative electrode sheet, which is then rolled to a compaction density of 1.2 mg / cm3. 2 .
[0063] Example 1
[0064] The negative electrode sheet prepared in Comparative Example 1 was used to perform matrix drilling on the two active layers 20 , with the hole spacing controlled to be 200 μm, the hole diameter controlled to be 50 μm, and the drilling depth to be 30 μm.
[0065] Example 2
[0066] The only difference between Example 2 and Example 1 is that the drilling depth is 50 μm.
[0067] Example 3
[0068] The only difference between Example 3 and Example 1 is that the drilling depth is 80 μm.
[0069] Example 4
[0070] The negative electrode sheet prepared in Comparative Example 1 was taken, and matrix holes were punched in the two active layers 20 , with the hole spacing controlled to be 200 μm, the punching depth controlled to be 50 μm, and the hole diameter controlled to be 20 μm.
[0071] Example 5
[0072] The only difference between Example 5 and Example 4 is that the pore size is controlled to be 80 μm.
[0073] Example 6
[0074] The negative electrode sheet prepared in Comparative Example 1 was used to perform matrix punching on the two active layers 20 , with the punching depth controlled to be 50 μm, the hole diameter controlled to be 50 μm, and the hole spacing of the punching being 50 μm.
[0075] Example 7
[0076] The only difference between Example 7 and Example 6 is that the hole pitch of the punched holes is 400 μm.
[0077] Example 8
[0078] Preparation method of negative electrode sheet:
[0079] Spherical silicon-carbon material is prepared by vapor-phase deposition of nanosilicon powder. This active material is then mixed with carbon black powder, CNTs, sodium carboxymethyl cellulose, and styrene-butadiene rubber, and stirred to form a negative electrode slurry. The active material content is 90%, the carbon black content is 2.5%, the CNT content is 2%, the dispersant sodium carboxymethyl cellulose content is 1%, and the styrene-butadiene rubber content is 4.5%. The negative electrode slurry is coated on both sides of copper foil to form a negative electrode sheet, which is then rolled to a compaction density of 1.2 mg / cm3. 2 .
[0080] The two active layers 20 of the negative electrode are punched, the punching depth is controlled to be 50 μm, the hole diameter is controlled to be 80 μm, and the punching spacing is controlled to be 200 μm. Figures 3-5 As shown in the SEM images, laser drilling can achieve precise location and speed drilling on the surface of the active layer 20, forming a uniform and orderly array of micropores on the negative electrode sheet. Furthermore, there is no noticeable loss or loosening of active material around or within the holes, demonstrating the high operability of this drilling method and its applicability in actual production.
[0081] The specific parameters and liquid absorption of the negative electrode sheets in Examples 1 to 7 and Comparative Example 1 are shown in Table 1 below:
[0082] Table 1
[0083]
[0084] The negative electrode sheets in Examples 1 to 7 and Comparative Example 1 were used to prepare button batteries and soft-pack batteries, respectively. The performance of the prepared batteries was tested. The test results are shown in Table 2 below:
[0085] Table 2
[0086]
[0087] As can be seen from Tables 1 and 2 above, as the drilling depth and the drilling hole diameter increase, the amount of liquid absorbed by the negative electrode sheet, the discharge capacity of the battery, the first efficiency, and the cycle performance all increase accordingly. Theoretically, the deeper the depth of the holes in the active layer 20 and the larger the pore diameter, the more conducive it is to the infiltration of the electrolyte, thereby improving the discharge capacity and cycle performance of the battery. However, drilling too deep or the pore diameter is too large may cause severe squeezing of the powder inside the electrode sheet, causing the powder in local areas to become loose and the adhesion to decrease, resulting in powder loss of the electrode sheet, thereby affecting the subsequent processing and safety performance of the negative electrode sheet, and further affecting the performance of the battery. Therefore, within the range of the depth and pore diameter of the above-mentioned first hole 30, while achieving better discharge capacity and cycle performance, it can also ensure the processing quality and safety performance of the negative electrode sheet.
[0088] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0089] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the appended claims, and the specification and drawings may be used to interpret the claims.
Claims
1. A negative electrode plate, characterized in that: The invention comprises a metal current collector and an active layer arranged on the surface of the metal current collector; a plurality of first holes are opened on the surface of the active layer away from the metal current collector.
2. The negative electrode sheet according to claim 1, characterized in that: The radial width of the first hole gradually narrows in a direction gradually approaching the metal current collector.
3. The negative electrode sheet according to claim 1, characterized in that: The pore size of the first hole is 1 μm to 100 μm; and / or, The depth of the first hole is 1 μm to 150 μm.
4. The negative electrode sheet according to claim 1, characterized in that: The first hole is a blind hole, and the depth of the first hole is 1 / 5 to 4 / 5 of the thickness of the active layer.
5. The negative electrode sheet according to claim 1, characterized in that: The distance between two adjacent first holes is 50 μm to 500 μm.
6. The negative electrode sheet according to claim 1, characterized in that: The first holes are distributed in a matrix.
7. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The metal current collector is provided with a second hole extending along the thickness direction thereof, the second hole is a blind hole, and the opening of the second hole is arranged toward the active layer.
8. The negative electrode sheet according to claim 7, characterized in that: The depth of the second hole is 0.5 μm to 10 μm; and / or, The depth of the second hole is less than or equal to 2 / 3 of the thickness of the metal current collector.
9. The negative electrode sheet according to any one of claims 1 to 5 and 8, characterized in that: The porosity of the negative electrode plate is 10% to 60%.
10. A secondary battery, characterized in that: The negative electrode sheet comprises the negative electrode sheet according to any one of claims 1 to 9.