Positive electrode lithium-rich composite current collector and method for manufacturing the same

Abstract

The present application relates to a lithium-rich composite current collector and a method for producing the same. [Means] The lithium-rich composite current collector includes a polymer layer, two aluminum plating layers, and two lithium-rich layers. The two aluminum plating layers are provided on both opposing surfaces of the polymer layer, and the two lithium-rich layers are provided on the surfaces of the two aluminum plating layers that are away from the polymer layer. In the above-mentioned embodiment, by providing the aluminum plating layer and the lithium-rich layer on the surface of the polymer layer, the lithium-rich composite current collector has higher strength and elongation, while the presence of the lithium-rich layer can compensate for the consumption of active lithium in the process of forming the SEI film (solid electrolyte interface) in the early stage after the lithium metal enters the battery, thereby improving the content of active lithium in the battery, and not only improving the capacity of the battery but also improving the cycle life of the battery.

Description

[Technical Field]

[0001] This application claims priority over Chinese Patent Application No. 2022104143441, filed on April 20, 2022, and International Application No. PCT / CN2022 / 095425, filed on May 27, 2022, the contents of those applications are incorporated herein by reference in their entirety.

[0002] This application relates to the technology of batteries, and more particularly to a lithium-rich composite current collector for positive electrodes and a method for manufacturing the same. [Background technology]

[0003] A current collector refers to a structure or component for collecting electric current, and in the case of lithium-ion batteries, it mainly refers to metal foil, such as copper foil or aluminum foil. More generally, it may also include tabs. The function of a current collector is primarily to link powdered active material by coating, collect and output the current from the active material, and input electrode current to the active material.

[0004] The positive electrode current collector of a typical non-aqueous secondary battery uses high-purity aluminum foil and is manufactured by the following steps: adding an aluminum ingot to an electrolytic aluminum molten liquid; refining the molten material by blowing a refining agent onto it with pure nitrogen gas or pure argon gas, stirring it thoroughly and uniformly, and then letting it stand; adding aluminum titanium boron threads in the opposite direction to refine the crystal grains; then degassing the aluminum liquid with pure nitrogen gas or pure argon gas in a degassing box; after degassing, filtration and purification of the aluminum liquid with a ceramic foam filter sheet; feeding the purified aluminum liquid into a rolling mill and rolling it to produce billets with a thickness of 5.0 mm to 10.0 mm; and finally cold rolling and annealing the billets to obtain the required thickness of aluminum foil, thus completing the manufacture of the current collector.

[0005] The current collector in the above-described embodiment is made of a single metal material and has a single function. When used inside a battery, it is only used to support the positive electrode and collect current, and cannot provide a wider range of functions. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Therefore, there is a need to provide a composite current collector for use in the positive electrode. For example, to solve the problem that the current collectors in the prior art have only one function, we provide a lithium-rich composite current collector and a method for manufacturing the same. [Means for solving the problem]

[0007] In one embodiment, the present application provides a lithium-rich composite current collector comprising a polymer layer, a metal layer, and a lithium-rich layer, wherein the metal layer is provided on the surface of the polymer layer, and the lithium-rich layer is provided on the surface of the metal layer that is away from the polymer layer.

[0008] Another aspect of the present invention provides a lithium-rich composite current collector for a positive electrode, comprising a polymer layer, two metal layers, and two lithium-rich layers, wherein the two metal layers are provided on opposing surfaces of the polymer layer, and the lithium-rich layers are provided on surfaces of the metal layers that are away from the polymer layer.

[0009] The above-described embodiment provides a lithium-rich composite current collector with higher strength and elongation by providing a metal layer and a lithium-rich layer on the surface of the polymer layer. Furthermore, because of the presence of the lithium-rich layer, the lithium metal, after entering the battery, can compensate for the consumption of active lithium during the formation process of the SEI film (solid electrolyte interface) in the preceding stage, thereby improving the active lithium content in the battery. This not only improves the battery capacity but also extends the battery's cycle life.

[0010] The following will further explain the technical proposal of this application.

[0011] In any embodiment, the metal layer is an aluminum plating layer.

[0012] In any embodiment, the aluminum content of the aluminum plating layer is 99.8% or more.

[0013] In any embodiment, the thickness of the lithium-rich composite current collector is 3 micrometers to 30 micrometers, of which the thickness of the polymer layer is 1 micrometer to 25 micrometers, the thickness of the metal layer is 0.3 micrometers to 3.0 micrometers, and the thickness of the lithium-rich layer is 0.5 micrometers to 2 micrometers.

[0014] In any embodiment, the peeling force between the metal layer and the polymer layer is 2 N / m or more.

[0015] In any embodiment, the polymer layer comprises a polymer film made of at least one selected from polyethylene, polypropylene, PET, and PPS.

[0016] In any embodiment, the lithium-rich layer comprises PVDF and carbon-coated lithium.

[0017] In one embodiment, the PVDF is made into a homopolymer structure.

[0018] In one embodiment, the carbon-coated lithium comprises lithium and a carbon material that completely coats the lithium.

[0019] In one embodiment, the carbon material in the carbon-coated lithium includes at least one of the following: carbon nanotubes, carbene (SP), isotropic spherical artificial graphite (KS-6), graphene, and vapor-grown carbon fiber (VGCF).

[0020] In any embodiment, the carbon-coated lithium is prepared by jet-milling pure lithium with an inert gas to obtain lithium powder with a particle size D50 of 0.5 to 1.0 μm, putting the lithium powder and carbon powder into a reaction kettle, stirring under vacuum for coating to obtain a carbon-coated lithium mixed powder, and sintering the carbon-coated lithium mixed powder under a vacuum environment to obtain carbon-coated lithium.

[0021] In any embodiment, the polymer layer has a puncture strength of 100 gf or more, a stretching strength MD of 200 MPa or more, a stretching strength TD of 200 MPa or more, an elongation rate MD of 30% or more, and an elongation rate TD of 30% or more.

[0022] As a second aspect, the present application is a method for manufacturing a lithium-rich composite current collector for manufacturing the lithium-rich composite current collector according to any one of the above-described embodiments, including depositing a metal on both opposite surfaces of the polymer layer by a vacuum coating apparatus to form the metal layer, and applying the carbon-coated lithium slurry to the surfaces of the two aluminum-plated layers away from the polymer layer to form the lithium-rich layer and obtain a lithium-rich composite current collector.

[0023] Hereinafter, the technical solution of the present application will be further described.

[0024] In any embodiment, the method includes preparing carbon-coated lithium particles, dissolving PVDF in an organic solvent, stirring for 60 to 100 min under a vacuum state to obtain a mixed solvent, and adding the carbon-coated lithium particles to the mixed solvent, stirring for 100 to 150 min under a vacuum state to obtain a carbon-coated lithium slurry.

[0025] In any embodiment, the method is A step of jet-pulverizing pure lithium with an inert gas to obtain lithium powder with a particle size D50 of 0.5 to 1.0 μm. The steps include: placing the lithium powder and carbon powder into a reaction vessel, vacuum stirring to coat them, and obtaining a carbon-coated lithium mixed powder; The process includes the step of sintering the carbon-coated lithium mixed powder in a vacuum environment to obtain carbon-coated lithium particles. [Brief explanation of the drawing]

[0026] The drawings, which constitute part of this application, are used to provide a further understanding of this application, and the exemplary embodiments and descriptions thereof are for interpretive purposes only and do not unduly limit this application.

[0027] To more clearly explain the technical concept in the embodiments of this application, the drawings necessary for use in the embodiments are briefly described below. Of course, the drawings in the following description are only a few embodiments of this application, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without any creative effort.

[0028] [Figure 1] This is a schematic diagram of the structure of a positive electrode lithium-rich composite current collector shown in one embodiment of the present invention. [Figure 2] Figure 1 is a schematic diagram of the structure of carbon-coated lithium particles in the lithium-rich layer. [Figure 3] This is a flowchart of a method for manufacturing a positive electrode lithium-rich composite current collector as shown in one embodiment of the present invention. [Explanation of symbols]

[0029] 100: Positive electrode lithium-rich composite current collector; 110: Polymer layer; 120: Metal layer; 130: Lithium-rich layer. [Modes for carrying out the invention]

[0030] To make the above-mentioned objectives, features, and advantages of the present application easier to understand, specific embodiments of the present application will be described in detail below with reference to the drawings. Many specific details are included in the following description to ensure a thorough understanding of the present application. However, the present application is not limited by the specific embodiments disclosed below, as it can be implemented in ways different from those described herein, and similar improvements can be made by those skilled in the art without departing from the intent of the present application.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art. Terms used herein are solely for the purpose of describing specific embodiments and are not intended to limit the application. The terms “including,” “having,” and any variations thereof used in the description of the specification, claims, and drawings herein are intended to cover non-exclusive inclusion.

[0032] In the description of embodiments of this application, the term "and / or" merely indicates a relationship to describe related objects, and there may be three types of relationships. For example, A and / or B indicates three situations: A existing alone, A and B existing simultaneously, or B existing alone. Also, the letter " / " in this specification usually indicates that the preceding and following related objects are in an "or" relationship.

[0033] In the description of this application, the directions and positional relationships indicated by terms such as "center," "vertical direction," "horizontal direction," "length," "width," "thickness," "top," "bottom," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," "axial direction," "radial direction," and "circumferential direction" are based on the directions and positional relationships shown in the drawings and are merely used to simplify and easily explain the description of this application. It should be understood that the devices or elements mentioned do not indicate or suggest that they have a specific direction or must be configured and operated from a specific direction. Therefore, it should be understood that this does not limit the present application.

[0034] Furthermore, the terms “first” and “second” are for descriptive purposes only and should not be understood as implicitly indicating the number of technical features shown that indicate or suggest relative importance. Thus, features limited to “first” and “second” may explicitly or implicitly include at least one such feature. In this description, “multiple” means at least two, for example, two, three, etc., unless otherwise specified.

[0035] In this description, the terms “attachment,” “connection,” “linking,” and “fixing” should be understood broadly unless otherwise explicitly defined or limited. For example, a connection may be fixed, detachable, or integrated; a connection may be mechanical; an electrical connection; a direct connection may be indirectly connected via an intermediate medium; or it may be an internal communication between two parts or an interaction between two parts. A person skilled in the art will understand the specific meaning of these terms in this description depending on the specific circumstances.

[0036] In this application, unless otherwise explicitly specified or limited, the presence of a first feature "above" or "below" a second feature may be in direct contact with the second feature, or it may be in indirect contact with the second feature via an intermediate mediator. Furthermore, the presence of a first feature "above," "above," and "on the top surface" of a second feature may be directly above and diagonally above the second feature, or simply indicate that the horizontal height of the first feature is greater than that of the second feature. The presence of a first feature "below," "below," and "on the bottom surface" of a second feature may be directly below and diagonally below the second feature, or simply indicate that the horizontal height of the first feature is lower than that of the second feature.

[0037] When an element is described as being "fixed" or "mounted" to another element, that element may be directly on the other element, or there may be an intervening element between them. When an element is considered to be "connected" to another element, that element may be directly connected to the other element, or there may be an intervening element between them simultaneously. The terms "vertical," "horizontal," "up," "down," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent only one embodiment.

[0038] The following describes preferred embodiments of the present invention, with reference to the drawings.

[0039] Figure 1 shows a lithium-rich composite current collector 100 according to one embodiment of the present invention, comprising a polymer layer 110, two metal layers 120, and two lithium-rich layers 130, wherein the two metal layers 120 are provided on opposite surfaces of the polymer layer 110, and the two lithium-rich layers 130 are provided on surfaces of the two aluminum plating layers 120 that are away from the polymer layer 110.

[0040] Lithium-ion batteries are a type of secondary battery (rechargeable battery) that primarily operates through the movement of lithium ions between the positive and negative electrodes. During the charging and discharging process, Li + It moves back and forth between the two electrodes, absorbing and releasing. During charging, Li+ During discharge, lithium is released from the positive electrode and absorbed into the negative electrode by the electrolyte, resulting in a lithium-rich state at the negative electrode. The reverse occurs during discharge.

[0041] By employing a lightweight polymer material for the polymer layer 110, the weight of the lithium-rich composite current collector 100 is lower than that of a pure metal current collector.

[0042] The metal layer 120 is an aluminum plating layer. The aluminum plating layer is provided on the surface of the polymer layer 110, and the strength of the polymer layer 110 can be improved by utilizing the physical properties of the metal.

[0043] The lithium-rich layer 130 contains lithium and is used to supplement the consumption of active lithium during the formation process of the SEI film (solid electrolyte interface) in the preceding stage. The lithium-rich layer 130 is not limited in terms of the amount of lithium it contains. Within a certain range, the higher the lithium content, the greater the supplementation of active lithium consumed in the preceding stage within the battery, and the higher the active lithium content in the battery. In the case of the lithium-rich layer 130, "lithium-rich" means that, unlike in the conventional technology where active lithium in the battery is consumed during the formation process of the SEI film and is not supplemented, in this embodiment, the active lithium in the battery is supplemented, resulting in a higher lithium content in the battery in this embodiment than in the lithium content in conventional batteries.

[0044] In the above-described embodiment, by providing a metal layer 120 and a lithium-rich layer 130 on the surface of the polymer layer 110, the lithium-rich composite current collector 100 has higher strength and elongation, while the presence of the lithium-rich layer 130 allows the lithium metal to supplement the consumption of active lithium during the formation process of the SEI film in the earlier stage after it enters the battery, thereby improving the active lithium content in the battery, which not only improves the battery capacity but also improves the battery's cycle life.

[0045] According to some embodiments of the present invention, preferably, the thickness of the lithium-rich composite current collector 100 is 3 micrometers (μm) to 30 micrometers, of which the thickness of the polymer layer 110 is 1 micrometer to 25 micrometers, the thickness of the metal layer 120 is 0.3 micrometers to 3.0 micrometers, and the thickness of the lithium-rich layer 130 is 0.5 micrometers to 2 micrometers. The lithium-rich composite current collector 100, being thinner than a pure metal current collector, allows more space within the battery to be allocated to the active material.

[0046] According to certain embodiments of the present application, preferably, the peel force between the metal layer 120 and the polymer layer 110 is 2 N / m or more. The peel force refers to the maximum force required when the bonded material is peeled off from the contact surface per unit width. It reflects the adhesive strength of the material.

[0047] By having a peeling force of 2 N / m or more between the metal layer 120 and the polymer layer 110, it is possible to reduce the likelihood of the short-circuit point between the metal layer 120 and the polymer layer 110 cracking or peeling due to the force.

[0048] According to some embodiments of the present application, preferably, the polymer layer 110 includes a polymer film made of at least one selected from polyethylene, polypropylene, PET (polyethylene terephthalate), and PPS (polyphenylene sulfide). The polymer layer 110 may include one or more of the above-mentioned types, and any combination of the above-mentioned polymer materials falls within the scope included in the present application.

[0049] According to some embodiments of the present application, preferably, the aluminum content of the aluminum plating layer is 99.8% or more.

[0050] Referring to Figure 2, according to some embodiments of the present application, the lithium-rich layer 130 preferably contains PVDF (polyvinylidene fluoride) and carbon-coated lithium. In this layer, the PVDF has a homopolymer structure. As shown in Figure 2, the structure of the carbon-coated lithium has a lithium metal core, with a large amount of carbon coating the outside of the lithium metal. The carbon material in the carbon-coated lithium includes at least one of carbon nanotubes, SP, KS-6, SO, graphene, and VGCF. The carbon material in the carbon-coated lithium may include one or more of the above-mentioned materials, and all combinations of the above-mentioned carbon materials fall within the scope of the present application.

[0051] PVDF has good dielectric and piezoelectric properties. Carbon is always used as a conductive material in batteries, and the carbon material in the lithium-rich layer 130 can improve the electron transport capability of the lithium-rich composite current collector 100. The lithium metal in the lithium-rich layer 130, after entering the battery, can supplement the consumption of active lithium during the formation process of the SEI film in the earlier stages, thereby increasing the active lithium content in the battery, which can improve not only the battery capacity but also the battery cycle life.

[0052] The carbon-coated lithium comprises lithium and a carbon material that completely coats the lithium. In the process of manufacturing the lithium-rich positive electrode current collector, the carbon material prevents contact between lithium and oxygen gas, thereby improving safety. Furthermore, pre-lithification of the carbon-coated lithium material provides better stability and safety.

[0053] When a lithium battery is first charged, the positive electrode is at a high potential, and the lithium in the carbon-coated lithium loses electrons to form lithium ions. These electrons then move towards the negative electrode after passing through the carbon layer and the current collector. The lithium ions are released from the carbon layer and enter the electrolyte, thereby improving the initial charge capacity of the lithium battery. After the lithium is released, the carbon material, being conductive, can reduce the interfacial resistance between the current collector and the positive electrode active material.

[0054] The carbon-coated lithium is A step of jet-pulverizing pure lithium with an inert gas to obtain lithium powder with a particle size D50 of 0.5 to 1.0 μm. The steps include: placing the lithium powder and carbon powder into a reaction vessel, vacuum stirring to coat them, and obtaining a carbon-coated lithium mixed powder; It is prepared by sintering the carbon-coated lithium mixed powder in a vacuum environment to obtain carbon-coated lithium.

[0055] By preparing carbon-coated lithium using the steps described above, the carbon material can be completely coated with metallic lithium.

[0056] According to some embodiments of the present application, preferably, the polymer layer 110 has a puncture strength of 100 gf or more, a tensile strength MD (Machine Direction) of 200 MPa or more, a transverse strength TD (Transverse Direction) of 200 MPa or more, an elongation MD of 30% or more, and an elongation TD of 30% or more.

[0057] Puncture strength is an important indicator of a separator, and the strength of the separator is determined by the force applied when an ejector pin penetrates the separator. Tension strength is the critical value at which a material transitions from uniform plastic deformation to localized concentrated plastic deformation, and is also the maximum load capacity of the material under static stretching conditions. Elongation is the percentage ratio of the total deformation ΔL of the gauge length section after stretching fracture of the sample to the original gauge length L: δ = ΔL / L × 100%.

[0058] In the above embodiment, since the positive electrode lithium-rich composite current collector 100 has an aluminum plating layer 120 on the surface of the polymer layer 110, the positive electrode lithium-rich composite current collector 100 has higher strength and elongation, with a puncture strength of 50 gf or more, a tensile strength MD of 150 MPa or more, a tensile strength TD of 150 MPa or more, an elongation MD of 10% or more, and an elongation TD of 10% or more. Furthermore, because of the presence of the lithium-rich layer 130, the electron transport capability of the composite current collector can be improved by carbon, increasing the active lithium content in the battery, and the upper and lower sheet resistances of the lithium-rich composite current collector 100 are both 50 mΩ or less. (Sheet resistance is block resistance, referring to the resistance from side to side of a square thin-film conductive material.)

[0059] This application provides a method for manufacturing a lithium-rich composite current collector 100 for producing a lithium-rich composite current collector 100 in any one of the embodiments described above, and includes the following steps: S01: Metal layers 120 are formed by depositing metal onto both opposing surfaces of the polymer layer 110. The metal layers 120 can be deposited onto the surface of the polymer layer 110 using a vacuum deposition apparatus, which may be a magnetron sputtering apparatus or a vacuum deposition apparatus. S03: A carbon-coated lithium slurry is applied to the surfaces of the two aluminum plating layers 120 that are away from the polymer layer 110 to form a lithium-rich layer 130 and obtain a lithium-rich composite current collector 100.

[0060] In this process, the metal is preferably high-purity aluminum, and the high-purity aluminum may be a high-purity aluminum ingot. The high-purity aluminum ingot is plated onto the surface of the polymer layer 110 using a vacuum deposition apparatus, and deposited onto both the upper and lower layers of the polymer thin film, respectively.

[0061] The deposition process parameters are: unwinding tension of 5-30N, winding tension of 5-25N, deposition speed exceeding 10m / min, evaporation temperature exceeding 600°C, and vacuum level of 8×10⁻⁶. -2It is less than Pa.

[0062] When applying a carbon-coated lithium slurry to the surface of the two aluminum plating layers 120 away from the polymer layer 110, the application can be carried out in an environment with a humidity of less than 1%.

[0063] In some embodiments, in S03, a carbon-coated lithium slurry is applied to the surfaces of the two metal layers 120 away from the polymer layer 110 to form a lithium-rich layer 130, after which the positive electrode lithium-rich composite current collector 100 is obtained by further division, winding, and vacuum packaging.

[0064] According to some embodiments of the present invention, preferably, the step S02 further includes preparing a carbon-coated lithium slurry, the step S02 comprising preparing carbon-coated lithium particles in S021, dissolving PVDF in an organic solvent and stirring under vacuum for 60 to 100 minutes to obtain a mixed solvent in S022, and adding the carbon-coated lithium particles to the mixed solvent and stirring under vacuum for 100 to 150 minutes to obtain a carbon-coated lithium slurry in S023.

[0065] In steps S022 and S023, high-speed stirring can be employed during stirring, with a stirring speed of 500 r / min or more. Preferably, the stirring speed is 1000 r / min.

[0066] In some embodiments, the organic solvent can be NMP (N-methylpyrrolidone) or DMAC (dimethylacetamide). In this embodiment, NMP is used as an example of the organic solvent. The mass ratio of the slurry is carbon-coated lithium:PVDF:NMP = 1:(0.01~0.015):(10~15).

[0067] NMP (N-methylpyrrolidone) is an organic compound with the chemical formula C5H9NO. It is a colorless to pale yellow transparent liquid with a slight ammonia odor. It is soluble in water in any ratio, dissolves in various organic solvents such as ethers, acetone and esters, halogenated hydrocarbons, and aromatic hydrocarbons, and can be completely mixed with almost all solvents.

[0068] According to certain embodiments of the present application, step S021 for preparing carbon-coated lithium particles preferably includes the following steps: S0211: Pure lithium is jet-pulverized with an inert gas to obtain lithium powder with a particle size D50 of 0.5 to 1.0 μm. S0212: The lithium powder and carbon powder are added to a reaction vessel and coated by vacuum stirring to obtain a carbon-coated lithium mixed powder. S0213: The carbon-coated lithium mixed powder is sintered in a vacuum environment to obtain carbon-coated lithium particles.

[0069] In step S0212, the stirring is performed at high speed, with a stirring speed of 500 r / min or more. Preferably, the stirring speed is 1000 r / min.

[0070] D50 is the particle size at which the cumulative particle size distribution percentage of a single sample reaches 50%. Its physical meaning is that 50% of the particles are larger than D50, and 50% are smaller. D50 is also called the median diameter.

[0071] In some embodiments, after obtaining carbon-coated lithium particles by sintering the carbon-coated lithium mixed powder in a vacuum environment in S0213, vacuum-sealed packaging may be performed to store the carbon-coated lithium particles.

[0072] According to the above embodiment, an 8-micrometer positive electrode lithium-rich composite current collector 100 can be manufactured by the following process (referred to as Example 1).

[0073] 1. A polymer thin film with a thickness of 4 micrometers and a 99.9% high-purity aluminum ingot were selected, and the polymer thin film and the high-purity aluminum ingot were respectively put into a vacuum coating equipment. The process adopted a vacuum evaporation process. The high-purity aluminum ingot was used to electroplate aluminum onto the polymer thin film by a vacuum evaporation device, and a thickness of 1 micrometer was evaporated on both the upper and lower layers of the polymer thin film. Among them, the evaporation process parameters were: unwind tension 8N, wind-up tension 6N, evaporation speed 80m / min, evaporation temperature 680°C, and vacuum degree 6×10 -2 Pa.

[0074] 2. Preparation of carbon-coated lithium particles: First, pure lithium was jet milled into lithium powder with a particle size D50 of 0.6μm with an inert gas. The lithium powder was coated with carbon powder in a reaction kettle under a vacuum environment (vacuum degree 6×10 -2 Pa) by high-speed stirring. The particle size after coating was 0.8 micrometers. After the coating was completed, it was sintered in a vacuum environment (vacuum degree 6×10 -2 Pa), and the vacuum degree was 6×10 -2 Pa. After the sintering was completed, vacuum sealing packaging was carried out.

[0075] 3. Preparation of carbon-coated lithium slurry: First, PVDF was dissolved in an organic solvent and stirred at high speed for 80 min under a vacuum state (vacuum degree 6×10 -2 Pa). The prepared carbon-coated lithium particles were added and stirred at high speed for 120 min under a vacuum state (vacuum degree 6×10 -2 Pa). The mass ratio of the slurry was carbon-coated lithium:PVDF:NMP = 1:0.012:10.

[0076] 4. The prepared carbon-coated lithium slurry was applied in an environment with a humidity of less than 1%.

[0077] 5. After the coating was completed, splitting, winding, and vacuum packaging were carried out.

[0078] For comparison, a conventional 8-micrometer aluminum foil positive electrode current collector is manufactured using the following steps (referred to as Comparative Example 1).

[0079] 1. The electrolytic aluminum molten material was fed into a smelting furnace, and aluminum ingots equivalent to 30% of the total weight of the electrolytic aluminum molten material were added, controlling the molten material temperature to 770°C. The mass percentages of each element in the molten material were adjusted to be Si: 0.15%, Fe: 0.48%, Cu: 0.13%, Mn: 1.3%, Ti: 0.03%, with the remainder being Al.

[0080] The molten material was refined by spraying a refining agent onto it with pure nitrogen gas or pure argon gas, and thoroughly and uniformly stirred for 9 minutes. After that, it was left to stand for 20 minutes to remove the dross from the surface of the aluminum molten material, and then placed in a standing furnace where the temperature inside the furnace was controlled to 755°C.

[0081] The aluminum liquid in the static furnace was fed into a trough, and aluminum-titanium-boron filaments were added in the opposite direction to refine the crystal grain. Subsequently, the aluminum liquid was degassed in a degassing box with pure nitrogen gas or pure argon gas. After degassing, the aluminum liquid was filtered and purified using a ceramic foam filter sheet.

[0082] 2. The purified aluminum liquid was fed into a rolling mill and cast and rolled to produce a billet with a thickness of 4.0 mm.

[0083] 3. The billet obtained in step a is cold-rolled to a thickness of 4.0 mm, and then homogenized annealing is performed at a temperature of 470°C for a duration of 25 hours.

[0084] 4. After the homogenized annealed billet is cold-rolled to a thickness of 0.5 mm, it is recrystallized and annealed at a temperature of 300°C for a duration of 15 hours.

[0085] 5. The recrystallized, annealed billet was rolled into 8-micrometer aluminum foil.

[0086] The table below shows a comparison between the 8-micrometer composite current collector manufactured in Example 1 and the 8-micrometer conventional aluminum foil positive electrode current collector manufactured in Comparative Example 1.

[0087] [Table 1]

[0088] In comparison, the tensile strength and ductility of the positive electrode lithium-rich composite current collector 100 according to the present invention were significantly improved compared to the conventional technology, for current collectors of similar thickness. On the other hand, after the positive electrode lithium-rich composite current collector 100 according to the present invention was manufactured as a lithium battery, the initial cycle efficiency of the lithium battery improved by 5%, and the battery cycle life improved from the conventional 1200 cycles to 1500 cycles.

[0089] Finally, the embodiments described above are merely illustrative and not limiting to the technical proposals of this application. Despite the detailed description of this application with reference to the embodiments described above, those skilled in the art will understand that the technical proposals described in the embodiments described above can still be modified, or some or all of the technical features therein can be substituted equally, and such modifications or substitutions should not deviate the essence of the corresponding technical proposals from the scope of the technical proposals in the embodiments of this application, and should remain within the scope of the claims and description of this application. In particular, unless there is a structural conflict, the technical features referred to in each embodiment can be combined in any form. This application is not limited to the specific embodiments disclosed herein, but includes all technical proposals that fall within the scope of the claims.

Claims

1. It comprises a polymer layer, a metal layer, and a lithium-rich layer. The metal layers are each provided on the surface of the polymer layer, and the lithium-rich layers are each provided on the surface of the metal layer that is separated from the polymer layer. The lithium-rich layer comprises polyvinylidene fluoride PVDF and carbon-coated lithium. Among them, PVDF forms a homopolymer structure, The carbon-coated lithium comprises lithium and a carbon material that completely coats the lithium. The carbon material in the carbon-coated lithium includes at least one of the following: carbon nanotubes, carbene SP, isotropic spherical artificial graphite KS-6, graphene, and vapor-grown carbon fiber VGCF. A lithium-rich composite current collector for positive electrodes, characterized by the following features.

2. The aforementioned metal layer is an aluminum plating layer. The lithium-rich composite current collector according to feature 1.

3. The aluminum content of the aforementioned aluminum plating layer is 99.8% or more. The lithium-rich composite current collector according to feature 2.

4. The thickness of the lithium-rich composite current collector is 3 micrometers to 30 micrometers, The thickness of the polymer layer is 1 micrometer to 25 micrometers, The thickness of the metal layer is 0.3 micrometers to 3.0 micrometers, The lithium-rich layer has a thickness of 0.5 micrometers to 2 micrometers, and includes at least one of these terms. The lithium-rich composite current collector according to feature 1.

5. The peeling force between the metal layer and the polymer layer is 2 N / m or more. The lithium-rich composite current collector according to feature 1.

6. The polymer layer includes a polymer film made up of at least one selected from polyethylene, polypropylene, polyethylene terephthalate (PET), and polyphenylene sulfide (PPS). The lithium-rich composite current collector according to feature 1.

7. The polymer layer is The puncture strength must be 100 gf or more, The tensile strength MD is 200 MPa or more, The tensile strength TD is 200 MPa or more, The growth rate MD is 30% or more, The growth rate TD is 30% or more, and includes at least one of the following: The lithium-rich composite current collector according to feature 1.

8. A method for manufacturing a lithium-rich composite current collector according to any one of claims 1 to 7, The steps include: depositing metal onto both opposing surfaces of the polymer layer to form the metal layer; The process includes the step of applying a carbon-coated lithium slurry to the surfaces of the two metal layers that are separated from the polymer layer, thereby forming the lithium-rich layer and obtaining a lithium-rich composite current collector. A method for manufacturing a lithium-rich composite current collector, characterized by the above.

9. moreover, The preparation of carbon-coated lithium particles, Dissolve PVDF in an organic solvent, stir under vacuum for 60-100 minutes to obtain a mixed solvent. The process includes adding the carbon-coated lithium particles to the mixed solvent and stirring under vacuum for 100 to 150 minutes to obtain a carbon-coated lithium slurry. A method for manufacturing a lithium-rich composite current collector according to feature 8.

10. moreover, A step of jet-pulverizing pure lithium with an inert gas to obtain lithium powder with a particle size D50 of 0.5 to 1.0 μm. The steps include: placing the lithium powder and carbon powder into a reaction vessel, vacuum stirring to coat them, and obtaining a carbon-coated lithium mixed powder; The step includes sintering the carbon-coated lithium mixed powder in a vacuum environment to obtain carbon-coated lithium particles, A method for manufacturing a lithium-rich composite current collector according to feature 9.

11. It comprises a polymer layer, two metal layers, and two lithium-rich layers. The two metal layers are provided on opposite surfaces of the polymer layer, and the two lithium-rich layers are provided on the surfaces of the two metal layers that are away from the polymer layer. The lithium-rich layer comprises polyvinylidene fluoride PVDF and carbon-coated lithium. Among them, PVDF forms a homopolymer structure, The carbon-coated lithium comprises lithium and a carbon material that completely coats the lithium. The carbon material in the carbon-coated lithium includes at least one of the following: carbon nanotubes, carbene SP, isotropic spherical artificial graphite KS-6, graphene, and vapor-grown carbon fiber VGCF. A positive electrode lithium-rich composite current collector characterized by the above.

Images