Current collectors, methods of making the same, and applications thereof

Abstract

The application provides a current collector, which comprises a porous base, a lithiumophilic prelithium film layer and a solid electrolyte film layer which are sequentially compounded on the pore wall surface of the porous base, the lithiumophilic prelithium film layer and the solid electrolyte film layer are also sequentially compounded on at least one surface of the porous base, and the solid electrolyte film layer completely fills the pores of the porous base; the lithiumophilic prelithium film layer comprises a lithiumophilic agent, a prelithium agent, an interface inducing agent and a polymer binder. The application also provides a preparation method and application of the current collector. The current collector provided by the application introduces the lithiumophilic prelithium film layer, and adds the lithiumophilic agent and the prelithium agent in the lithiumophilic prelithium film layer, so that the safety of the battery is improved, the energy density and the rate performance of the battery are obviously improved, the battery polarization is reduced, and the cycle life of the battery is prolonged.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to current collectors, their preparation methods, and their applications. Background Technology

[0002] Secondary batteries typically use aluminum and copper foil as current collectors for the positive and negative electrodes, respectively. The negative current collector is more crucial in determining the battery's internal resistance than the positive current collector, thus significantly impacting its lifespan and cycle stability. Conventional aluminum and copper foils can only conduct electrons on their two surfaces, but not lithium. + Therefore, excessively high local current can easily cause lithium dendrite growth, leading to battery failure and making it difficult to meet market demand.

[0003] Porous current collectors can fully utilize their porous structure and high specific surface area to improve the cycle stability and lifespan of lithium-ion batteries, effectively solving the aforementioned problems. However, most porous current collectors currently use direct coating or bonding of solid electrolyte layers, which improves perforation leakage, electronic and ionic conductivity, and battery power performance to some extent. However, since solid electrolytes lack lithium affinity, the active material within the current collector pores experiences excessively high nucleation potentials as interfaces form, causing most metallic lithium to deposit on the surface of the porous current collector, resulting in a decrease in electronic conductivity, which is actually lower than that of conventional current collectors. Furthermore, the ionic conductivity is also affected by the interface, with lithium ions choosing the shortest migration path, leaving the large internal hollow structure unutilized and failing to effectively improve the utilization rate of the active material. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a current collector that can improve the utilization rate of internal pores and strengthen the adhesion of active materials, thereby improving the safety, cycle performance and rate performance of the battery.

[0005] In view of this, this application provides a current collector, comprising a porous substrate, a lithium-affinity pre-lithiated thin film layer and a solid electrolyte thin film layer sequentially bonded to the pore wall surface of the porous substrate, wherein the lithium-affinity pre-lithiated thin film layer and the solid electrolyte thin film layer are also sequentially bonded to at least one surface of the porous substrate, and the solid electrolyte thin film layer completely fills the pores of the porous substrate.

[0006] The lithiophilic pre-lithiation thin film layer includes a lithiophile, a pre-lithiation agent, an interface inducer, and a polymer binder.

[0007] Preferably, in the lithiophilic pre-lithiophilic thin film layer, the lithiophilic agent is selected from one or more of Ag, Ag₂O, ZnO, MnO₂, CaO, MgO, and Au; and / or, the pre-lithiophilic agent is selected from one or more of Li₂NiO₂, Li₂CuO₂, Li₂CoO₂, Li₂O₂, Li₃N, M / Li₂O, metallic lithium, lithium silicide, aqueous solutions of electrolytic lithium salts, and lithium alloys, wherein M is selected from one or more of Fe, Co, Ni, and Mn; and / or, the interface inducer is selected from ZnBr₂, A gBr, MgBr2, MnBr4, ethanol, polyethylene glycol, glycerol, butanediol, tributyl ester, and silicone; and / or, the polymer binder is selected from one or more of polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, alkylated polyethylene oxide, polyvinylpyrrolidone, ethyl acrylate, ethylene-vinyl acetate copolymer, polyvinyl acetate, polycarbonate, cellulose acetate propionate, maleic anhydride or its derivatives, polyacrylonitrile, polysiloxane, gelatin, and starch.

[0008] Preferably, based on the total mass of the lithiophile, the pre-lithiophile, the interface inducer, and the polymer binder, the content of the lithiophile is 1-50%, the content of the pre-lithiophile is 1-25%, the content of the interface inducer is 1-30%, and the content of the polymer binder is 10-60%.

[0009] Preferably, the solid electrolyte thin film layer comprises a solid electrolyte, a conductive agent, and a polymer binder;

[0010] And / or, the general formula of the solid electrolyte is shown in formula (I):

[0011] Li n [A (3-a'-a") A' (a') A″ (a") [B] (2-b'-b") B' (b') B″ (b") ][C' (c') C″ (c") O 12 (Ⅰ);

[0012] Where A, A', and A" represent the dodecahedral positions of the crystal structure.

[0013] A represents one or more trivalent rare earth elements.

[0014] A' represents one or more alkaline earth elements.

[0015] A″ represents one or more alkali metal elements other than Li.

[0016] 0≤a'≤2,0≤a″≤1;

[0017] B, B', and B" represent the octahedral positions in the crystal structure.

[0018] B represents one or more tetravalent elements.

[0019] B' represents one or more pentavalent elements.

[0020] "B" represents one or more hexavalent elements.

[0021] 0≤b', 0≤b" and b'+b″≤2;

[0022] C' and C" represent the tetrahedral positions in the crystal structure.

[0023] C' represents one or more of Al, Ga, and boron.

[0024] "C" represents one or more of Si and Ge.

[0025] 0≤c'≤0.5 and 0≤c″≤0.4

[0026] n = 7 + a' + 2a″ - b' - 2b″ - 3c' - 4c″ and 4.5 ≤ n ≤ 7.5;

[0027] And / or, the conductive agent is selected from one or more of carbon nanotubes, carbon fibers, graphene, conductive carbon black, and conductive graphite; and / or, the polymer binder is selected from one or more of polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, alkylated polyethylene oxide, polyvinylpyrrolidone, ethyl acrylate, ethylene-vinyl acetate copolymer, polyvinyl acetate, polycarbonate, cellulose acetate propionate, maleic anhydride or its derivatives, polyacrylonitrile, polysiloxane, gelatin, and starch;

[0028] And / or, based on the total mass of the solid electrolyte, the conductive agent, and the polymer binder, the content of the solid electrolyte is 3-90%, the content of the conductive agent is 0-80%, and the content of the polymer binder is 0-50%.

[0029] Preferably, the porous substrate is selected from porous aluminum foil or porous copper foil, the thickness of the porous substrate is 2 to 1500 μm, and the pore size is 0.1 to 24 μm; the thickness of the lithiophilic pre-lithiated film layer is 0.01 to 10 μm, and the thickness of the solid electrolyte film layer is 0.1 to 35 μm.

[0030] This application also provides a method for preparing a current collector, comprising the following steps:

[0031] A) Mix the lithiophile, pre-lithiophile, interface inducer and polymer binder to obtain the first suspension;

[0032] B) Using the first suspension, a pre-lithophile thin film layer is prepared on the pore wall surface and at least one surface of the porous substrate;

[0033] C) Prepare a solid electrolyte film layer on the surface of the pre-lithiophilic thin film layer, and make the solid electrolyte film layer completely fill the pores of the porous substrate.

[0034] Preferably, in step B), the preparation method specifically includes:

[0035] The first suspension is coated on the surface of the pore wall and at least one surface of the porous substrate; or, the porous substrate is immersed in the first suspension and then taken out and heat-treated.

[0036] In step C), the preparation method is specifically as follows:

[0037] A second suspension is obtained by mixing a solid electrolyte, a conductive agent, a polymer binder, and a solvent.

[0038] The second suspension is coated onto the surface of the current collector obtained in step B); or the current collector obtained in step B) is immersed in the second suspension.

[0039] The porous matrix was prepared by hydrogen template method.

[0040] This application also provides an electrode, comprising a current collector and an active material layer composited on the surface of the current collector, wherein the current collector is the current collector described above or the current collector prepared by the preparation method described above.

[0041] Preferably, the electrode is a positive electrode, and the active material of the active material layer is a ternary positive electrode material; the electrode is a negative electrode, and the active material of the active material layer is a silicon-based material.

[0042] This application also provides a lithium-ion battery, including a positive electrode, a separator, and a negative electrode, characterized in that the positive electrode or the negative electrode is the electrode described above.

[0043] This application provides a current collector comprising a porous current collector, a lithiophilic pre-lithiation film layer and a solid electrolyte film layer sequentially laminated to the pore wall surface of the porous substrate, wherein the lithiophilic pre-lithiation film layer and the solid electrolyte film layer are also sequentially laminated to at least one surface of the porous substrate, and the solid electrolyte film layer completely fills the pores of the porous substrate; further, the lithiophilic pre-lithiation film layer comprises a lithiophilic agent, a pre-lithiation agent, an interface inducer, and a polymer binder; the interface inducer in the lithiophilic pre-lithiation film layer of the current collector provided in this application has a strong affinity and / or bonding ability with the porous current collector substrate. The introduction of lithiophiles and pre-lithiophiles onto the substrate surface improves porosity utilization and induces uniform distribution of metallic lithium inside and outside the current collector pores. This effectively reduces the local current density of the electrode and the excessively high nucleation potential within the pores, resulting in uniform current distribution. Simultaneously, it provides abundant nucleation potential, inducing uniform lithium deposition and stabilizing and inhibiting lithium dendrite growth. Furthermore, the solid electrolyte film layer completely fills the pores of the porous substrate, greatly improving the porosity utilization of the current collector. This enhances battery safety, significantly improves energy density and rate performance, reduces battery polarization, and extends battery cycle life.

[0044] Furthermore, the solid electrolyte and conductive agent are simultaneously introduced into the solid electrolyte film layer composited on the surface of the lithium-loving pre-lithiate film layer. While ensuring that the electrode surface has high lithium-ion interconnection characteristics, it also has high electronic conductivity, which further stabilizes and improves the rate and cycle performance of the battery. Attached Figure Description

[0045] Figure 1 This is a cross-sectional view of the current collector of the present invention;

[0046] Figure 2 This is a cross-sectional view of the electrode sheet of the present invention;

[0047] Figure 1 In the diagram, 1 represents the porous substrate, 2 represents the lithium-loving pre-lithiated thin film layer, and 3 represents the solid electrolyte thin film layer.

[0048] Figure 2 In the diagram, 1 represents the porous substrate, 2 represents the lithium-loving pre-lithiated thin film layer, 3 represents the solid electrolyte thin film layer, and 4 represents the active material layer. Detailed Implementation

[0049] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0050] To improve the structural utilization rate of porous current collectors and ultimately enhance the overall performance of lithium-ion batteries, this application provides a current collector comprising a porous current collector. A composite layer is defined on the surface and pore walls of the porous current collector, and a lithiophilic agent and a pre-lithiophilic agent are introduced. This allows for full utilization of the current collector's porosity, ultimately improving the safety, energy density, and rate performance of the lithium-ion battery, as well as extending its cycle life. Specifically, an embodiment of this invention discloses a current collector, the cross-sectional view of which is shown below. Figure 1 As shown, 1 is a porous substrate, 2 is a lithium-affinity pre-lithiated thin film layer, and 3 is a solid electrolyte thin film layer. Specifically, the current collector includes a porous substrate, a lithium-affinity pre-lithiated thin film layer and a solid electrolyte thin film layer sequentially composited on the pore wall surface of the porous substrate, the lithium-affinity pre-lithiated thin film layer and the solid electrolyte thin film layer are also sequentially composited on at least one surface of the porous substrate, and the solid electrolyte thin film layer completely fills the pores of the porous substrate.

[0051] The lithiophilic pre-lithiation thin film layer includes a lithiophile, a pre-lithiation agent, an interface inducer, and a polymer binder.

[0052] In the current collector provided in this application, the porous substrate can be specifically selected from porous aluminum foil or porous copper foil, preferably prepared by a hydrogen template method. Specifically, during the electrochemical deposition process of the aluminum foil or copper foil, tiny hydrogen bubbles are precipitated at the cathode, serving as a dynamic template. The hydrogen bubbles aggregate on the metal surface to form pores, and metal ions can only be deposited in the gaps between the bubble templates, resulting in a porous structure. Porous current collectors with different pore sizes are prepared by optimizing the concentration of the electroplating solution, the electroplating time, and the amount of surfactant added. The porous substrate prepared by the hydrogen template method in this application has a thickness of 2–1500 μm and a pore size of 0.1–24 μm; specifically, the thickness of the porous substrate is 10–1000 μm and the pore size is 1–20 μm. The porous substrate in this application has uniform pore size, uniform distribution, and high porosity.

[0053] The porous substrate has a lithium-philic pre-lithiation film layer laminated to the pore wall surface, and the lithium-philic pre-lithiation film layer is laminated to at least one surface of the porous substrate; that is, the lithium-philic pre-lithiation film layer is laminated to the pore wall surface and the upper surface of the porous substrate, or the lithium-philic pre-lithiation film layer is laminated to the pore wall surface and the lower surface of the porous substrate, or the lithium-philic pre-lithiation film layer is laminated to the pore wall surface, the upper surface and the lower surface of the porous substrate; and the lithium-philic pre-lithiation film layer does not completely fill the pores of the porous substrate. The thickness of the lithium-philic pre-lithiation film layer is 0.01 to 10 μm, specifically, the thickness of the lithium-philic pre-lithiation film layer is 0.5 to 5 μm. The lithium-philic pre-lithiation film layer improves the utilization rate of the huge hollow structure inside the porous substrate.

[0054] The aforementioned lithiophilic pre-lithiation thin film layer comprises a lithiophile, a pre-lithiation agent, an interface inducer, and a polymer binder. The lithiophile and the pre-lithiation agent are core functional materials. The lithiophile increases the lithiophilic potential within the pores, allowing more lithium to be attracted and filled into the current collector pores during battery charging and discharging, thus increasing pore utilization. The pre-lithiation agent is used for lithium replenishment. The interface inducer improves the contact interface between the lithiophile, the pre-lithiation agent, and the porous substrate. The polymer binder has polymerization and bonding effects to bond the aforementioned materials to the surface of the porous substrate.

[0055] Specifically, the lithiophile is selected from one or more of Ag, Ag₂O, ZnO, MnO₂, CaO, MgO, and Au. In a specific embodiment, the lithiophile is selected from ZnO. The pre-lithiophile is selected from one or more of Li₂NiO₂, Li₂CuO₂, Li₂CoO₂, Li₂O₂, Li₃N, M / Li₂O, metallic lithium, lithium silicide, aqueous solutions of electrolytic lithium salts, and lithium alloys. M is selected from one or more of Fe, Co, Ni, and Mn. M / Li₂O represents a mixture of M and Li₂O. In a specific embodiment, the pre-lithiophile is selected from Li₂NiO₂ or lithium silicide.

[0056] The interface inducer is selected from one or more of ZnBr2, AgBr, MgBr2, MnBr4, ethanol, polyethylene glycol, glycerol, butanediol, tributyl ester, and silica gel. Specifically, the interface inducer is selected from one or more combinations of ZnBr2, AgBr, MgBr2, MnBr4, ethanol, polyethylene glycol, glycerol, butanediol, tributyl ester, and silica gel. For example, the interface inducer can be a combination of bromide and alcohol / ester compound: ZnBr2, AgBr, MgBr2, MnBr4, etc. A combination of at least one of r4 and at least one of ethanol, polyethylene glycol, glycerol, butanediol, and tributyl ester, or a combination of an alcohol / ester compound and silica gel: at least one of ethanol, polyethylene glycol, glycerol, butanediol, tributyl ester, and silica gel, or a bromide alone: ​​at least one of ZnBr2, AgBr, MgBr2, and MnBr4; in specific embodiments, the interface inducer is selected from a combination of polyethylene glycol and silica gel, MgBr2, butanediol, or a combination of MgBr2 and butanediol.

[0057] The polymer binder is selected from one or more of polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, alkylated polyethylene oxide, polyvinylpyrrolidone, ethyl polyacrylate, ethylene-vinyl acetate copolymer, polyvinyl acetate, polycarbonate, cellulose acetate propionate, maleic anhydride or its derivatives, polyacrylonitrile, polysiloxane, gelatin and starch; in a specific embodiment, the polymer binder is selected from polyvinylidene fluoride.

[0058] In the lithiophilic pre-lithiation film layer, based on the total mass of the lithiophilic agent, the pre-lithiation agent, the interface inducer, and the polymer binder, the content of the lithiophilic agent is 1-50%, the content of the pre-lithiation agent is 1-25%, the content of the interface inducer is 1-30%, and the content of the polymer binder is 10-60%; specifically, the content of the lithiophilic agent is 5-45%, the content of the pre-lithiation agent is 6-20%, the content of the interface inducer is 5-20%, and the content of the polymer binder is 15-50%.

[0059] The current collector provided in this application further includes a solid electrolyte film layer, which is laminated to the surface of the lithiophilic pre-lithiophilic film layer, and the solid electrolyte film layer completely fills the pores of the porous substrate. Based on the lithiophilic pre-lithiophilic film layer, the lithiophilic pre-lithiophilic film layer and the solid electrolyte film layer are sequentially laminated to the pore wall surfaces of the porous substrate. On the surface of the porous substrate, the lithiophilic pre-lithiophilic film layer and the solid electrolyte film layer are sequentially laminated to the upper surface, or the lithiophilic pre-lithiophilic film layer and the solid electrolyte film layer are sequentially laminated to the lower surface, or both the upper and lower surfaces are sequentially laminated to the lithiophilic pre-lithiophilic film layer and the solid electrolyte film layer, with the lithiophilic pre-lithiophilic film layer directly laminated to the pore wall surfaces. The thickness of the solid electrolyte film layer is 0.1–35 μm, specifically, the thickness of the solid electrolyte film layer is 1–10 μm. In a specific embodiment, the thickness of the solid electrolyte film layer is greater than the thickness of the lithiophilic pre-lithiophilic film layer.

[0060] In the solid electrolyte thin film layer, the general formula of the solid electrolyte is as shown in formula (Ⅰ):

[0061] Li n [A (3-a'-a") A' (a') A″ (a") [B] (2-b'-b") B' (b') B″ (b") ][C' (c') C″ (c") O 12 (Ⅰ);

[0062] Where A, A', and A" represent the dodecahedral positions of the crystal structure.

[0063] A represents one or more trivalent rare earth elements.

[0064] A' represents one or more alkaline earth elements.

[0065] A″ represents one or more alkali metal elements other than Li.

[0066] 0≤a'≤2,0≤a″≤1;

[0067] B, B', and B" represent the octahedral positions in the crystal structure.

[0068] B represents one or more tetravalent elements.

[0069] B' represents one or more pentavalent elements.

[0070] "B" represents one or more hexavalent elements.

[0071] 0≤b', 0≤b" and b'+b″≤2;

[0072] C' and C" represent the tetrahedral positions in the crystal structure.

[0073] C' represents one or more of Al, Ga, and boron.

[0074] "C" represents one or more of Si and Ge.

[0075] 0≤c'≤0.5 and 0≤c″≤0.4

[0076] n = 7 + a' + 2a″ - b' - 2b″ - 3c' - 4c″ and 4.5 ≤ n ≤ 7.5.

[0077] Specifically, the solid electrolyte is selected from LLZTO, LLTO, and LLZO. In a specific embodiment, the solid electrolyte is selected from LLZTO. The conductive agent is selected from one or more of carbon nanotubes, carbon fibers, graphene, conductive carbon black, and conductive graphite. In a specific embodiment, the conductive agent is selected from conductive carbon black. The polymer binder is selected from one or more of polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, alkylated polyethylene oxide, polyvinylpyrrolidone, ethyl polyacrylate, ethylene-vinyl acetate copolymer, polyvinyl acetate, polycarbonate, cellulose acetate propionate, maleic anhydride or its derivatives, polyacrylonitrile, polysiloxane, gelatin, and starch. In a specific embodiment, the polymer binder is selected from polyvinylidene fluoride.

[0078] In the solid electrolyte film, based on the total mass of the solid electrolyte, conductive agent, and polymer binder, the content of the solid electrolyte is 3-90%, the content of the conductive agent is 0-80%, and the content of the polymer binder is 0-50%; specifically, the content of the solid electrolyte is 20-80%, the content of the conductive agent is 20-60%, and the content of the polymer binder is 10-40%.

[0079] This application also provides a method for preparing a current collector, comprising the following steps:

[0080] A) Mix the lithiophile, pre-lithiophile, interface inducer and polymer binder to obtain the first suspension;

[0081] B) Using the first suspension, a pre-lithophile thin film layer is prepared on the pore wall surface and at least one surface of the porous substrate;

[0082] C) Prepare a solid electrolyte film layer on the surface of the pre-lithiophilic thin film layer, and make the solid electrolyte film layer completely fill the pores of the porous substrate.

[0083] In the current collector preparation process, this application first mixes a lithiophile, a pre-lithiophile, an interface inducer, and a polymer binder to obtain a first suspension. The mixing method is performed in accordance with methods well known to those skilled in the art, and this application has no particular limitations on this. Before the above mixing, the lithiophile, pre-lithiophile, and interface inducer are preferentially pretreated respectively. Specifically, they are dried at 60°C, then ground and passed through a 200-mesh sieve to obtain a powder with uniform particle size for later use, so as to make the suspension more uniform and the mixing effect better. A small amount of water and N-methylpyrrolidone (NMP) are added to the polymer binder during the adhesive application process.

[0084] This application then utilizes the first suspension to prepare a pre-lithophile thin film layer on the pore wall surface and at least one surface of the porous substrate; the specific preparation method is as follows:

[0085] The first suspension is coated on the surface of the pore wall of the porous matrix and at least one surface;

[0086] Alternatively, the porous matrix can be immersed in the first suspension and then removed and heat-treated.

[0087] The specific method of coating described above is carried out in accordance with the methods known to those skilled in the art, and there are no particular limitations in this application.

[0088] According to the present invention, a solid electrolyte film layer is finally prepared on the surface of the pre-lithiophilic thin film layer, and then subjected to heat treatment to ensure that the solid electrolyte film layer completely fills the pores of the porous substrate. The specific preparation process is as follows:

[0089] A second suspension is obtained by mixing a solid electrolyte, a conductive agent, a polymer binder, and a solvent.

[0090] The second suspension is coated onto the surface of the current collector obtained in step B);

[0091] Alternatively, the current collector obtained in step B) can be immersed in the second suspension.

[0092] In the above steps, the solvent in the second suspension is specifically N-methylpyrrolidone (NMP). The coating method is performed in a manner well known to those skilled in the art, and this application does not impose any particular limitations on it.

[0093] This application also provides an electrode sheet, which includes a current collector and an active material layer composited on the surface of the current collector, wherein the current collector is the current collector described in the above-described scheme; a cross-sectional view of the electrode sheet is shown below. Figure 2 As shown, 1 is a porous substrate, 2 is a lithiophilic pre-lithiated thin film layer, 3 is a solid electrolyte thin film layer, and 4 is an active material layer.

[0094] The aforementioned electrode can be either a positive or negative electrode. When the electrode is a positive electrode, the active material of the active material layer is a ternary positive electrode material, specifically selected from nickel-cobalt-manganese ternary materials, and more specifically LiNi. 0.8 Co 0.1 Mn 0.1 O2; when the electrode is a negative electrode, the active material of the active material layer is selected from silicon-based materials, specifically silicon-carbon negative electrode materials.

[0095] In this application, the active material layer is laminated onto the surface of the current collector in a manner known to those skilled in the art, and this application does not impose any particular limitations on this.

[0096] This application also provides a lithium-ion battery, including a positive electrode, a separator, and a negative electrode, wherein the positive electrode or the negative electrode is the electrode described in the above-described scheme.

[0097] To further understand the present invention, the current collector, its preparation method and its application are described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0098] The method for preparing a current collector includes the following steps:

[0099] 1) A porous current collector matrix was prepared using the hydrogen template method. By controlling process parameters such as H2SO4 concentration, CuSO4 concentration, current density, electroplating time, and surfactant addition in the electrodeposition solution, the pore size and thickness of the three-dimensional porous current collector were adjusted to meet the required dimensions.

[0100] 2) Pre-treat the lithiophile, pre-lithiophile, and interface inducer separately to obtain granular powder or solution of a certain fineness for later use. Mix the pre-treated lithiophile, pre-lithiophile, and interface inducer with the polymer binder in a certain mass ratio, stir evenly, and then prepare a suspension.

[0101] 3) Coat the surface of the current collector substrate obtained in step 1) with the suspension obtained in step 2), heat treat it and set it aside for later use to obtain a lithiophilic pre-lithiated thin film layer;

[0102] 4) Mix the solid electrolyte particles, conductive agent and polymer binder according to the specified ratio, dissolve them in a solvent, stir evenly, and then prepare a suspension.

[0103] 5) The current collector obtained in step 3) is coated a second time using the current collector obtained in step 4) to obtain a current collector with a solid electrolyte film layer on the surface.

[0104] The current collector was prepared using the above method, with specific parameters and conditions as described in the following examples and comparative examples:

[0105] Example 1 - Positive Electrode

[0106] A lithiumophilic pre-lithiophilic film layer was coated on a 10 μm thick porous aluminum foil (prepared by hydrogen template method). The lithiumophilic pre-lithiophilic film layer consisted of: 45% ZnO, 15% Li2NiO2, 20% polyethylene glycol + silicone (1:1) and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was a double-layer coating. After heat treatment, a second LLZTO film was coated, which consisted of 35% LLZTO, 33% conductive carbon and 32% polyvinylidene fluoride. The coating thickness on one side was 2 μm, and it was a double-sided coating. The total thickness was 10 + 0.5 + 0.5 + 2 + 2 = 15 μm.

[0107] Example 2 - Positive Electrode

[0108] A lithiumophilic pre-lithiophilic film layer was coated on a 10 μm thick porous aluminum foil (prepared by hydrogen template method). The lithiumophilic pre-lithiophilic film layer included: 50% ZnO, 15% Li2NiO2, 15% polyethylene glycol + silicone (1:1) and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was double-coated. After heat treatment, a second LLZTO film was coated, which included 35% LLZTO, 35% conductive carbon and 30% polyvinylidene fluoride. The coating thickness on one side was 2 μm, and it was double-coated. The total thickness was 10 + 0.5 + 0.5 + 2 + 2 = 15 μm.

[0109] Example 3 - Positive Electrode

[0110] A lithiophilic pre-lithiophilic film layer was coated on a 10 μm thick porous aluminum foil (prepared by hydrogen template method). The lithiophilic pre-lithiophilic film layer included: 45% ZnO, 15% Li2NiO2, 20% polyethylene glycol + silicone (1:1) and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was a single-layer coating. After heat treatment, a second LLZTO film was coated, which included 35% LLZTO, 33% conductive carbon and 32% polyvinylidene fluoride. The coating thickness was 2 μm on one side and it was double-sided coated. The total thickness was 10 + 0.5 + 2 + 2 = 14.5 μm.

[0111] Example 4 - Positive Electrode

[0112] A lithium-philic pre-lithiated film layer was coated on a 10 μm thick porous aluminum foil (prepared by dealloying method). The lithium-philic pre-lithiated film layer consisted of: 45% ZnO, 15% Li2NiO2, 20% polyethylene glycol + silicone (1:1) and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was a double-layer coating. After heat treatment, a second LLZTO film was coated, consisting of 35% LLZTO, 33% conductive carbon and 32% polyvinylidene fluoride. The coating thickness on one side was 2 μm, and it was a double-sided coating with a total thickness of 10 + 0.5 + 0.5 + 2 + 2 = 15 μm.

[0113] Example 5 - Positive Electrode

[0114] A lithiumophilic pre-lithiophilic film layer was coated on a 10 μm thick porous aluminum foil (prepared by hydrogen template method). The lithiumophilic pre-lithiophilic film layer consisted of 45% ZnO, 15% Li2NiO2, 20% MgBr2, and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was a double-layer coating. After heat treatment, a second LLZTO film layer was coated, consisting of 35% LLZTO, 33% conductive carbon, and 32% polyvinylidene fluoride. The coating thickness on one side was 2 μm, and it was a double-sided coating with a total thickness of 10 + 0.5 + 0.5 + 2 + 2 = 15 μm.

[0115] Example 6 - Positive Electrode

[0116] A lithiumophilic pre-lithiophilic film layer was coated on a 10 μm thick porous aluminum foil (prepared by hydrogen template method). The lithiumophilic pre-lithiophilic film layer included: ZnO 45%, Li2NiO2 15%, butanediol 20%, and polyvinylidene fluoride 20%. The coating thickness was 0.5 μm, and it was a double-layer coating. After heat treatment, a second LLZTO film layer was coated, which included LLZTO 35%, conductive carbon 33%, and polyvinylidene fluoride 32%. The coating thickness on one side was 2 μm, and it was a double-sided coating. The total thickness was 10 + 0.5 + 0.5 + 2 + 2 = 15 μm.

[0117] Example 7 - Positive Electrode

[0118] A lithiumophilic pre-lithiophilic film layer was coated on a 10 μm thick porous aluminum foil (prepared by hydrogen template method). The lithiumophilic pre-lithiophilic film layer included: 45% ZnO, 15% Li2NiO2, 20% MgBr2 + butanediol (1:1), and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was a double-layer coating. After heat treatment, a second LLZTO film was coated, which contained 35% LLZTO, 33% conductive carbon, and 32% polyvinylidene fluoride. The coating thickness on one side was 2 μm, and it was a double-sided coating with a total thickness of 10 + 0.5 + 0.5 + 2 + 2 = 15 μm.

[0119] Example 8 - Negative Electrode

[0120] A lithiumophilic pre-lithiophilic film layer was coated on a 4.5 μm thick porous copper foil (prepared by hydrogen template method). The lithiumophilic pre-lithiophilic film layer included: 45% ZnO, 15% lithium silicide powder, 20% polyethylene glycol + silica gel (1:1), and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was coated on both sides. After heat treatment, an LLZTO film was coated, which contained 35% LLZTO, 33% conductive carbon, and 32% polyvinylidene fluoride. The coating thickness was 2 μm on one side, and it was coated on both sides. The total thickness was 4.5 + 0.5 + 0.5 + 2 + 2 = 9.5 μm.

[0121] Example 9 - Negative Electrode

[0122] 1) A lithiumophilic pre-lithiated film layer was coated on a porous copper foil (prepared by hydrogen template method) with a thickness of 4.5 μm. The lithiumophilic pre-lithiated film layer included: 50% ZnO, 15% lithium silicide powder, 15% polyethylene glycol + silica gel (1:1), and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was coated on both sides. After heat treatment, an LLZTO film was coated, which included 35% LLZTO, 35% conductive carbon, and 30% polyvinylidene fluoride. The coating thickness was 2 μm on one side, and it was coated on both sides. The total thickness was 4.5 + 0.5 + 0.5 + 2 + 2 = 9.5 μm.

[0123] Example 10 - Negative Electrode

[0124] A lithiumophilic pre-lithiophilic film layer was coated on a porous copper foil (prepared by hydrogen template method) with a thickness of 4.5 μm. The lithiumophilic pre-lithiophilic film layer included: 45% ZnO, 15% lithium silicide powder, 20% polyethylene glycol + silicone (1:1) and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm and it was coated on one side only. After heat treatment, an LLZTO film was coated, which contained 35% LLZTO, 33% conductive carbon and 32% polyvinylidene fluoride. The coating thickness was 2 μm on one side only and it was coated on both sides. The total thickness was 4.5 + 0.5 + 2 + 2 = 9 μm.

[0125] Example 11 - Negative Electrode

[0126] A lithium-philic pre-lithiated film layer was coated on a porous copper foil (prepared by dealloying) with a thickness of 4.5 μm. The lithium-philic pre-lithiated film layer included: 45% ZnO, 15% lithium silicide powder, 20% polyethylene glycol + silica gel (1:1), and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was coated on both sides. After heat treatment, an LLZTO film was coated, which included 35% LLZTO, 33% conductive carbon, and 32% polyvinylidene fluoride. The coating thickness was 2 μm on one side, and it was coated on both sides. The total thickness was 4.5 + 0.5 + 0.5 + 2 + 2 = 9.5 μm.

[0127] Comparative Example 1 - Positive Electrode

[0128] An LLZTO film is coated on a porous aluminum foil with a thickness of 10 μm, containing 35% LLZTO, 33% conductive carbon, and 32% polyvinylidene fluoride. The coating thickness is 2 μm on one side and double-sided, with a total thickness of 10 + 2 + 2 = 14 μm.

[0129] Comparative Example 2 - Positive Electrode

[0130] An LLZTO film is coated on a 10μm thick ordinary aluminum foil, containing 35% LLZTO, 33% conductive carbon, and 32% polyvinylidene fluoride. The coating thickness is 2μm on one side and double-sided, with a total thickness of 10+2+2=14μm.

[0131] Comparative Example 3 - Negative Electrode

[0132] An LLZTO film was coated on a porous copper foil (prepared by hydrogen template method) with a thickness of 4.5 μm, wherein LLZTO 35%, conductive carbon 33%, and polyvinylidene fluoride 32% were used. The coating thickness was 2 μm on one side and double-sided coating, with a total thickness of 4.5 + 2 + 2 = 8.5 μm.

[0133] Comparative Example 4 - Negative Electrode

[0134] An LLZTO film was coated on a 4.5 μm thick ordinary copper foil (prepared by hydrogen template method), containing 35% LLZTO, 33% conductive carbon, and 32% polyvinylidene fluoride. The coating thickness was 2 μm on one side and double-sided, with a total thickness of 4.5 + 2 + 2 = 8.5 μm.

[0135] Comparative Example 5 - Negative Electrode

[0136] A lithium-philic pre-lithiophilic film layer was applied to a porous copper foil (prepared by hydrogen template method) with a thickness of 4.5 μm. The lithium-philic pre-lithiophilic film layer included: 60% ZnO, 0% lithium silicide powder, 20% polyethylene glycol + silica gel (1:1), and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was coated on both sides. After heat treatment, an LLZTO film was coated, which contained 35% LLZTO, 33% conductive carbon, and 32% polyvinylidene fluoride. The coating thickness was 2 μm on one side, and it was coated on both sides. The total thickness was 4.5 + 0.5 + 0.5 + 2 + 2 = 9.5 μm.

[0137] Comparative Example 6 - Negative Electrode

[0138] A lithium-philic pre-lithiophilic film layer was applied to a porous copper foil (prepared by hydrogen template method) with a thickness of 4.5 μm. The lithium-philic pre-lithiophilic film layer included: 0% ZnO, 60% lithium silicide powder, 20% polyethylene glycol + silica gel (1:1), and 20% polyvinylidene fluoride. The coating thickness was 0.5 μm, and it was coated on both sides. After heat treatment, an LLZTO film was coated, which contained 35% LLZTO, 33% conductive carbon, and 32% polyvinylidene fluoride. The coating thickness was 2 μm on one side, and it was coated on both sides. The total thickness was 4.5 + 0.5 + 0.5 + 2 + 2 = 9.5 μm.

[0139] Comparative Example 7 - Negative Electrode

[0140] A lithium-philic pre-lithiated film layer was applied to a porous copper foil (prepared by hydrogen template method) with a thickness of 4.5 μm. The lithium-philic pre-lithiated film layer included: 45% ZnO, 15% lithium silicide powder, 0% polyethylene glycol + silica gel (1:1), and 40% polyvinylidene fluoride. The coating thickness was 0.5 μm, and the film was coated on both sides. After heat treatment, an LLZTO film was coated, which contained 35% LLZTO, 33% conductive carbon, and 32% polyvinylidene fluoride. The coating thickness was 2 μm on one side, and the film was coated on both sides. The total thickness was 4.5 + 0.5 + 0.5 + 2 + 2 = 9.5 μm.

[0141] The current collector prepared above is used to prepare the positive electrode (the positive electrode active material is LiNi). 0.8 Co 0.1 Mn 0.1 O2), the corresponding negative electrode is a conventional silicon-carbon negative electrode sheet, which is wound to form a battery, and the battery performance is compared and evaluated; or the current collector prepared above is used to prepare a negative electrode sheet (the negative electrode active material is silicon-carbon negative electrode material), and the corresponding positive electrode is a conventional positive electrode sheet (the positive electrode active material is LiNi). 0.8 Co 0.1 Mn 0.1 O2), wound into batteries, and the battery performance was compared and evaluated. Specific data are shown in Table 1.

[0142] Table 1 Performance data of batteries prepared in the examples and comparative examples

[0143]

[0144]

[0145] As can be seen from the performance results of the above embodiments and comparative examples in Table 1, the current collector provided by this application improves the pore utilization rate and active material utilization rate and improves the lithium dendrite condition at the interface by introducing a lithiophilic pre-lithiophilic thin film layer and by selecting lithiophilic agents and pre-lithiophilic agents in the lithiophilic pre-lithiophilic thin film layer, thereby improving the battery safety, capacity retention rate and cycle life to a certain extent.

[0146] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0147] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A current collector, comprising a porous substrate, a lithium-affinity pre-lithiated thin film layer and a solid electrolyte thin film layer sequentially bonded to the pore wall surface of the porous substrate, wherein the lithium-affinity pre-lithiated thin film layer and the solid electrolyte thin film layer are further sequentially bonded to at least one surface of the porous substrate, and the solid electrolyte thin film layer completely fills the pores of the porous substrate; The lithiophilic pre-lithiation thin film layer includes a lithiophile, a pre-lithiation agent, an interface inducer, and a polymer binder; In the lithium-affinity pre-lithiation thin film layer, the lithium-affinity agent is selected from one or more of Ag, Ag₂O, ZnO, MnO₂, CaO, MgO, and Au; the pre-lithiation agent is selected from one or more of Li₂NiO₂, Li₂CuO₂, Li₂CoO₂, Li₂O₂, Li₃N, M / Li₂O, metallic lithium, lithium silicide, aqueous solutions of electrolytic lithium salts, and lithium alloys. M is selected from one or more of Fe, Co, Ni, and Mn; the interface inducing agent is selected from one or more of ZnBr2, AgBr, MgBr2, MnBr4, ethanol, polyethylene glycol, glycerol, butanediol, tributyl ester, and silicone; the polymer binder is selected from one or more of polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, alkylated polyethylene oxide, polyvinylpyrrolidone, ethyl acrylate, ethylene-vinyl acetate copolymer, polyvinyl acetate, polycarbonate, cellulose acetate propionate, maleic anhydride or its derivatives, polyacrylonitrile, polysiloxane, gelatin, and starch; The solid electrolyte thin film layer includes a solid electrolyte, a conductive agent, and a polymer binder; The general formula of the solid electrolyte is shown in formula (Ⅰ): Li n [A (3-a'-a") and (a') A″ (a") ][B (2-b'-b") B' (b') B″ (b") ][C' (c') C″ (c") ] Oh 12 (Ⅰ); Where A, A', and A" represent the dodecahedral positions of the crystal structure. A represents one or more trivalent rare earth elements. A' represents one or more alkaline earth elements. A″ represents one or more alkali metal elements other than Li. 0≤a'≤2,0≤a″≤1; B, B', and B" represent the octahedral positions in the crystal structure. B represents one or more tetravalent elements. B' represents one or more pentavalent elements. "B" represents one or more hexavalent elements. 0≤b', 0≤b" and b'+b″≤2; C' and C" represent the tetrahedral positions in the crystal structure. C' represents one or more of Al, Ga, and boron. "C" represents one or more of Si and Ge. 0≤c'≤0.5 and 0≤c″≤0.4 n = 7 + a' + 2a″ - b' - 2b″ - 3c' - 4c″ and 4.5 ≤ n ≤ 7.

5.

2. The current collector according to claim 1, characterized in that, Based on the total mass of the lithiophile, the pre-lithiophile, the interface inducer, and the polymer binder, the content of the lithiophile is 1-50%, the content of the pre-lithiophile is 1-25%, the content of the interface inducer is 1-30%, and the content of the polymer binder is 10-60%.

3. The current collector according to claim 1, characterized in that, The conductive agent is selected from one or more of carbon nanotubes, carbon fibers, graphene, conductive carbon black, and conductive graphite; the polymer binder is selected from one or more of polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, alkylated polyethylene oxide, polyvinylpyrrolidone, ethyl acrylate, ethylene-vinyl acetate copolymer, polyvinyl acetate, polycarbonate, cellulose acetate propionate, maleic anhydride or its derivatives, polyacrylonitrile, polysiloxane, gelatin, and starch. Based on the total mass of the solid electrolyte, the conductive agent, and the polymer binder, the content of the solid electrolyte is 3-90%, the content of the conductive agent is 0-80%, and the content of the polymer binder is 0-50%.

4. The current collector according to claim 1, characterized in that, The porous substrate is selected from porous aluminum foil or porous copper foil, the thickness of the porous substrate is 2~1500μm, and the pore size is 0.1~24μm; the thickness of the lithiophilic pre-lithiated film layer is 0.01~10μm, and the thickness of the solid electrolyte film layer is 0.1~35μm.

5. The method for preparing the current collector according to any one of claims 1 to 4, comprising the following steps: A) Mix the lithiophile, pre-lithiophile, interface inducer and polymer binder to obtain the first suspension; B) Using the first suspension, a pre-lithophile thin film layer is prepared on the pore wall surface and at least one surface of the porous substrate; C) Prepare a solid electrolyte film layer on the surface of the pre-lithiophilic thin film layer, and make the solid electrolyte film layer completely fill the pores of the porous substrate.

6. The preparation method according to claim 5, characterized in that, In step B), the preparation method is specifically as follows: The first suspension is coated on the surface of the pore wall and at least one surface of the porous substrate; or, the porous substrate is immersed in the first suspension and then taken out and heat-treated. In step C), the preparation method is specifically as follows: A second suspension is obtained by mixing a solid electrolyte, a conductive agent, a polymer binder, and a solvent. The second suspension is coated onto the surface of the current collector obtained in step B); or the current collector obtained in step B) is immersed in the second suspension. The porous matrix was prepared by hydrogen template method.

7. An electrode comprising a current collector and an active material layer composited on the surface of the current collector, wherein the current collector is the current collector according to any one of claims 1 to 4 or the current collector prepared by the preparation method according to any one of claims 5 to 6.

8. The electrode sheet according to claim 7, characterized in that, The electrode is a positive electrode, and the active material of the active material layer is a ternary positive electrode material; the electrode is a negative electrode, and the active material of the active material layer is a silicon-based material.

9. A lithium-ion battery, comprising a positive electrode, a separator, and a negative electrode, characterized in that, The positive electrode or the negative electrode is the electrode as described in any one of claims 7 to 8.

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