Current collector, electrode and battery

Abstract

The utility model provides a current collector, an electrode and a battery, the current collector comprises a plurality of mutually wound conductive fibers, the current collector is provided with pores formed among the conductive fibers, and the porosity of the current collector is 30%-60%. According to the current collector, the plurality of conductive fibers are mutually wound to form the current collector, and the gaps exist among the mutually wound conductive fibers, so that the electrolyte can enter the current collector from the side surface of the current collector through the gaps, namely, a new infiltration channel is provided for the electrolyte, and the infiltration effect of the electrolyte on an electrode can be improved; by controlling the porosity of the current collector, sufficient space can be provided for electrolyte infiltration, and the contact surface of the electrolyte and the active material is enlarged, so that the electrical performance of the battery is improved, and the strength of the current collector is ensured.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a current collector, an electrode, and a battery. Background Technology

[0002] Whether it's a power battery or an energy storage battery, the electrodes inside the cell basically use copper or aluminum foil as current collectors. To improve the energy density of the cell, many cell manufacturers have adopted an ultra-thick electrode design to increase the mass of active material per unit area of ​​the current collector. However, this lengthens the ion transport path and increases the conductivity burden on the current collector. In this case, using sheet-like metal foil as the current collector can only play a supporting and conductive role, and it is difficult to solve the problem of insufficient electrolyte wettability of ultra-thick electrodes. Utility Model Content

[0003] The embodiments of this utility model provide a current collector, an electrode, and a battery, which can improve the technical problem of insufficient electrolyte wettability in ultra-thick electrodes.

[0004] In a first aspect, embodiments of the present invention provide a current collector comprising: a plurality of interconnected conductive fiber filaments, the current collector having pores formed between the conductive fiber filaments, the porosity of the current collector being 30%-60%.

[0005] In one embodiment, the diameter of the conductive fiber is 1μm-12μm.

[0006] In one embodiment, the thickness of the current collector is 5 μm-20 μm.

[0007] In one embodiment, the conductive fiber filament is a metal fiber filament.

[0008] In one embodiment, the surface of the conductive fiber is provided with a conductive layer.

[0009] In one embodiment, the conductive layer is a carbon layer.

[0010] Secondly, embodiments of the present invention provide an electrode, comprising the aforementioned current collector and an electrode material layer disposed on the current collector.

[0011] In one embodiment, the electrode material layer includes a first sublayer disposed on the surface of the current collector and a second sublayer embedded in the current collector, wherein the thickness ratio of the first sublayer to the second sublayer is (1-10):1.

[0012] In one embodiment, electrode material layers are provided on both sides of the current collector, and the ratio of the sum of the thicknesses of the second sub-layers on both sides of the current collector to the thickness of the current collector is (0.3-1):1.

[0013] In one embodiment, the thickness of the electrode is L2, the thickness of the current collector is L1, the ratio of L2 to L1 is greater than 18, and the conductive fiber is a metal fiber.

[0014] In one embodiment, the thickness of the electrode is 100μm-300μm.

[0015] Secondly, embodiments of this utility model provide a battery including the electrodes described above.

[0016] The beneficial effects of the embodiments of this utility model are as follows:

[0017] In embodiments of this invention, multiple conductive fibers are intertwined to form a current collector, and there are pores between the intertwined conductive fibers, allowing the electrolyte to enter the current collector from the side through the pores. This provides a new wetting channel for the electrolyte, thereby improving the wetting effect of the electrolyte on the electrode. By controlling the porosity of the current collector, sufficient space can be provided for electrolyte wetting, increasing the contact area between the electrolyte and the active material, thereby improving the electrical performance of the battery while ensuring the strength of the current collector. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a cross-sectional view of the electrode provided in an embodiment of this utility model;

[0020] Figure 2 and Figure 3 This is a schematic diagram of the braided structure of the current collector provided in an embodiment of this utility model.

[0021] Explanation of reference numerals in the attached figures: 1-conductive fiber filament; 2-electrode material layer; first sublayer-21; second sublayer-22. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of the present utility model and are not intended to limit the present utility model. In the present utility model, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0023] Please see Figure 1-3 In a first aspect, embodiments of the present invention provide a current collector comprising: a plurality of interconnected conductive fiber filaments 1, the current collector having pores formed between the conductive fiber filaments 1, and the porosity of the current collector being 30%-60%, for example, 30%, 32%, 35%, 37%, 40%, 42%, 45%, 47%, 50%, 52%, 55%, 57%, 60%, etc.

[0024] It can be understood that by using multiple conductive fiber filaments 1 to form a current collector through intertwining, and with pores existing between the intertwined conductive fiber filaments 1, the electrolyte can enter the current collector from the side through the pores, thus providing a new wetting channel for the electrolyte (see example). Figure 1 The region between the second sublayer 22 allows for better contact between the electrolyte and the active material, improving the electrolyte's wetting effect on the electrode. Simultaneously, the current collector formed by the winding of conductive fiber filament 1 has a high specific surface area, providing more attachment points for the active material, thus increasing the amount of active material adhering to it and the mass of active material per unit area of ​​the current collector, thereby improving the cell's energy density. For the same mass of active material adhering to a unit area of ​​the current collector, the current collector formed by the winding of conductive fiber filament 1 is thinner, thereby shortening the ion transport path and improving the electrode's conductivity. By controlling the porosity of the current collector, sufficient space can be provided for electrolyte wetting, increasing the contact area between the electrolyte and the active material, thereby improving the battery's electrical performance while ensuring the strength of the current collector.

[0025] It is understandable that the porosity of the current collector can be controlled by adjusting the diameter and pore size of the multiple intertwined conductive fibers. Controlling the porosity of the current collector allows the active material to adhere stably to it, while also providing sufficient wetting channels for the electrolyte.

[0026] It is understandable that, compared to the conventionally used metal foil as the current collector, the current collector in this application is formed by the intertwining of conductive fiber filaments 1, with the filaments 1 interlacing with each other. The resulting current collector structure is stable and can also provide stable support for the electrode material layer 2. In addition, the current collector of this structure also has a certain adhesive effect, which can replace the adhesive to firmly bond the current collector to the electrode material layer 2, thereby increasing the proportion of active material in the electrode material layer 2 and thus improving the energy density of the battery.

[0027] It is understood that the current collector of this application is formed by intertwining multiple conductive fiber filaments 1, which can improve the flexibility of the current collector and reduce the probability of electrode breakage caused by long-term bending, thereby improving the performance of the current collector and extending its service life.

[0028] It is understandable that there are multiple pores between the conductive fiber filaments 1, and the size of these pores can be the same or different. The current collector formed by the intertwining of multiple conductive fiber filaments 1 can be approximated as a sheet, and the electrolyte can penetrate into the current collector from two surfaces and four sides. Porosity refers to the percentage of pore volume in a bulk material to the total volume of the material in its natural state. The formula for calculating porosity P is:

[0029]

[0030] Where P is the porosity of the material, in %;

[0031] V0 is the volume of the material in its natural state, or apparent volume, measured in cm³. 3 or m 3 ;

[0032] ρ0 is the bulk density of the material, in g / cm³. 3 or kg / m 3 ;

[0033] V is the absolute dense volume of the material, in cm³. 3 or m 3 ;

[0034] ρ is the material density, with units of g / cm³. 3 or kg / m 3 .

[0035] It is understandable that multiple conductive fiber filaments 1 can form a current collector through weaving or through random winding. As an example, the multiple conductive fiber filaments 1 can be divided into warp and weft threads, and a current collector is formed by the interweaving of the warp and weft threads (e.g., ...). Figure 3 (As shown). Multiple conductive fiber filaments 1 can also be divided into fiber filaments with different orientations, which interweave to form a current collector (e.g., Figure 2 (As shown).

[0036] As an example, the conductive fiber 1 can be formed into a filamentous structure by calendering or spinning, possessing the conductive properties of conventional metal foil current collectors. In one embodiment, the diameter of the conductive fiber 1 is 1μm-12μm, for example, it can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, etc. This allows the current collector to have suitable pore size and porosity while ensuring its strength.

[0037] In one embodiment, the thickness of the current collector is 5μm-20μm, for example, it can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, etc. This makes the current collector easy to process, provides good conductivity, and controls the space it occupies within the battery cell.

[0038] In one embodiment, a conductive layer is provided on the surface of the conductive fiber filament 1.

[0039] It is understood that by providing a conductive layer on the surface of the conductive fiber 1, the conductivity of the conductive fiber 1 can be improved, thereby enhancing the conductivity of the electrode. As an example, the conductive layer can be applied to the surface of the conductive fiber 1 by coating, such as by spraying.

[0040] In one embodiment, the conductive fiber filament 1 is a metal fiber filament.

[0041] It is understandable that metal fibers have better toughness than metal sheets. Therefore, the tensile strength of metal fibers is higher than that of metal sheets, which can improve the tensile strength of the current collector. In addition, metal fibers have the advantages of high specific strength, high specific stiffness, high strength and toughness, and controllable porosity, which can improve the strength, toughness and rigidity of the current collector.

[0042] As an example, the conductive fiber 1 can be formed into a filamentous metal by means of calendering or spinning, and it has the conductive properties of conventional metal foil current collectors. The metal fiber 1 includes at least one of copper fiber 1, aluminum fiber 1, and nickel fiber 1. For example, when the current collector is used as the positive electrode, the conductive fiber 1 can be made of aluminum fiber 1; when the current collector is used as the negative electrode, the negative electrode can be made of one or more of copper fiber 1, aluminum fiber 1, and nickel fiber 1.

[0043] In one embodiment, the conductive layer is a carbon layer. As an example, the carbon layer includes at least one of graphene, carbon nanotubes, carbon fibers, carbon black, and metallic conductive carbon. Among them, metallic conductive carbon is a conductive material composed of metal particles and carbon materials, and has high conductivity.

[0044] Secondly, embodiments of the present invention provide an electrode, comprising the aforementioned current collector and an electrode material layer 2 disposed on the current collector.

[0045] It is understood that by using the above-mentioned current collector, the wettability of the electrolyte to the electrode can be improved, making it easier for the electrode material layer 2 on the electrode to be fully wetted by the electrolyte, thereby increasing the mass of active material per unit area of ​​the electrode and improving the conductivity of the electrode.

[0046] As an example, the electrode can be either a positive electrode or a negative electrode.

[0047] When the electrode is a positive electrode, the electrode material layer 2 on the surface of the positive electrode includes a positive active material, a dispersant, and a conductive agent. The specific ratio of the positive active material, dispersant, and conductive agent can be set as needed. The electrode material layer 2 can be formed by wet coating. Specifically, the positive active material, dispersant, and conductive agent are mixed in a solvent in a certain ratio, then coated onto at least one surface of the current collector, and dried to obtain the positive electrode. The electrode material layer 2 can also be prepared by dry method. Specifically, the positive active material, dispersant, and conductive agent are directly mixed uniformly in powder form, and then deposited onto at least one surface of the current collector to obtain the positive electrode. The positive active material is a commonly used positive active material in lithium-ion batteries, including but not limited to chemical formulas such as Li. x Ni h Co y M z O 2-d N d (where 0.95≤x≤1.2, h>0, y≥0, z≥0, and h+y+z=1, 0≤d≤1, M is selected from one or more combinations of Mn and Al, and N is selected from one or more combinations of F, P, and S) The positive electrode active material may also be, but is not limited to, LiCoO2, LiNiO2, LiVO2, LiCrO2, LiMn2O4, LiCoMnO4, Li2NiMn3O8, LiNi 0.5 Mn 1.5The cathode active material can be one or more of the following: O4, LiCoPO4, LiMnPO4, LiFePO4, LiNiPO4, LiCoFSO4, CuS2, FeS2, MoS2, NiS, TiS2, etc. The positive electrode active material can also be modified. Methods for modifying the positive electrode active material are known to those skilled in the art. For example, coating, doping, etc., can be used to modify the positive electrode active material. The materials used for modification can be one or more of the following, including but not limited to Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce, W, etc. The positive electrode active material can also be at least one of sodium transition metal oxides, sodium polyanionic compounds, and sodium Prussian blue analogues. The sodium-based cathode active material is at least one of sodium transition metal oxides, sodium polyanionic compounds, and sodium Prussian blue analogues; wherein, sodium transition metal oxides include NaCoO2, NaFeO2, NaNiO2, NaNiFeMnO2, NaCuFeMnO2, NaNi... 0.5 Mn 0.5 Any of the following: O2; any of the following: sodium polyanionic compounds: Na3V2(PO4)3, NaFePO4, Na2Fe2(SO4)3, Na2Fe2P2O7; any of the following: sodium Prussian blue analogues: NaFeFe(CN)6, Na2CoFe(CN)6, Na2NiFe(CN)6.

[0048] When the electrode is a negative electrode, the electrode material layer 2 on the surface of the negative electrode includes a negative electrode active material, a dispersant, and a conductive agent. The specific ratio of the negative electrode active material, dispersant, and conductive agent can be set as needed. The electrode material layer 2 can be formed by wet coating. Specifically, the negative electrode active material, dispersant, and conductive agent are mixed in a solvent in a certain ratio, then coated on at least one surface of the current collector, and dried to obtain the negative electrode. The electrode material layer 2 can also be prepared by dry method. Specifically, the negative electrode active material, dispersant, and conductive agent are directly mixed uniformly in powder form, and then deposited on at least one surface of the current collector to obtain the negative electrode. The negative electrode active material is a commonly used negative electrode active material in lithium-ion batteries, including but not limited to one or more of graphite, soft carbon, hard carbon, carbon fiber 12, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate, or other metals that can form alloys with lithium. The graphite may be selected from one or more of artificial graphite, natural graphite, and modified graphite; the silicon-based material may be selected from one or more of elemental silicon, silicon oxide, silicon-carbon composite, and silicon alloy; and the tin-based material may be selected from one or more of elemental tin, tin oxide, and tin alloy.

[0049] In one embodiment, the electrode material layer 2 includes a first sub-layer 21 disposed on the surface of the current collector and a second sub-layer 22 embedded in the current collector. The thickness ratio of the first sub-layer 21 and the second sub-layer 22 is (1-10):1, for example, it can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.

[0050] It is understandable that, since the current collector is formed by multiple conductive fiber filaments 1 intertwined, and there are pores between the conductive fiber filaments 1, when the electrode material layer 2 is placed on the current collector, part of the electrode slurry used to prepare the electrode material layer 2 can penetrate into the current collector through the pores between the conductive fiber filaments 1 and solidify to form a second sub-layer 22 embedded in the current collector. Part of the electrode slurry adheres to the surface of the current collector and solidifies to form a first sub-layer 21 located on the surface of the current collector. The electrode material of the second sub-layer 22 embedded in the current collector can fully contact the current collector, thereby shortening the ion transport path and improving the conductivity of the electrode. The thicker the first sub-layer 21, the lower the conductivity of the electrode and the longer the mass transport channel. The electrode material layer 2 includes electrode materials, such as positive electrode active materials or negative electrode active materials.

[0051] In one embodiment, electrode material layers 2 are provided on both sides of the current collector, and the ratio of the sum of the thicknesses of the second sub-layers 22 on both sides of the current collector to the thickness of the current collector is (0-0.7):1, for example, it can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, etc.

[0052] It is understandable that the ratio of the sum of the thicknesses of the second sub-layers 22 on both sides of the current collector to the thickness of the current collector can be controlled. Figure 1 The size of the region between the second sublayer 22 controls the conductivity of the electrode.

[0053] In one embodiment, the thickness of the electrode is L2, the thickness of the current collector is L1, the ratio of L2 to L1 is greater than 18, and the conductive fiber filament 1 is a metal fiber filament.

[0054] It is understandable that metal fibers possess advantages such as high specific strength, high specific stiffness, high strength and toughness, and controllable porosity, thereby enhancing the strength, toughness, and rigidity of the current collector. By using metal fibers as the conductive fiber filament 1, the diameter of the conductive fiber filament 1 can be reduced while ensuring the strength, toughness, and rigidity of the current collector. This can increase the ion transfer rate and the specific surface area of ​​the current collector. Simultaneously, since the electrode material can be embedded between the metal fibers, the total thickness of the current collector can be increased, allowing the current collector to carry more electrode material, thereby improving the energy density of the electrode.

[0055] In one embodiment, the thickness of the electrode is 100μm-300μm, for example, it can be 100μm, 120μm, 140μm, 160μm, 180μm, 200μm, 220μm, 240μm, 260μm, 280μm, 300μm, etc.

[0056] Secondly, embodiments of this utility model provide a battery including the electrodes described above.

[0057] The embodiments of this utility model have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A current collector, characterized in that, The current collector comprises: a plurality of mutually intertwined conductive fiber filaments, the current collector having pores formed between the conductive fiber filaments, the porosity of the current collector being 30%-60%.

2. The current collector of claim 1, wherein The diameter of the conductive fiber filaments is 1 μm-12 μm.

3. The current collector of claim 1, wherein The thickness of the current collector is 5 μm-20 μm.

4. The current collector of claim 1, wherein The conductive fiber filaments are metal fiber filaments.

5. The current collector of claim 1, wherein The surface of the conductive fiber filaments is provided with a conductive layer.

6. The current collector of claim 5, wherein The conductive layer is a carbon layer.

7. An electrode characterized by, The electrode comprises the current collector as claimed in any one of claims 1-6 and an electrode material layer provided on the current collector.

8. The electrode of claim 7, wherein The electrode material layer comprises a first sublayer provided on the surface of the current collector and a second sublayer embedded in the current collector, the thickness ratio of the first sublayer to the second sublayer being (1-10):

1.

9. The electrode of claim 8, wherein Both sides of the current collector are provided with the electrode material layer, the sum of the thicknesses of the second sublayers on both sides of the current collector to the thickness of the current collector being (0.3-1):

1.

10. The electrode of claim 7, wherein The thickness of the electrode is L2, the thickness of the current collector is L1, the ratio of L2 to L1 is greater than 18, and the conductive fiber filaments are metal fiber filaments.

11. The electrode of claim 7, wherein The thickness of the electrode is 100 μm-300 μm.

12. A battery, characterized by The electrode comprises the electrode as claimed in any one of claims 7-11.

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