Interface chemical bonding microporous copper foil current collector, and preparation method and application thereof

Abstract

The present application relates to an interface chemical bonding microporous copper foil current collector and a preparation method and application thereof. The current collector comprises: a microporous copper foil substrate, which is a calendered copper foil or an electrolytic copper foil, and has a microporous structure thereon; a copper surface anchoring layer, which is composed of a bifunctional organic molecule; wherein the first functional group comprises one or more of sulfydryl -SH or -NH2, for forming a coordination bond or a covalent bond with the copper surface, so that the bifunctional organic molecule is anchored on the surface of the microporous copper foil substrate and the inner wall of the microporous structure; the second functional group comprises one or more of -COOH, -PO4 or -Si(OR)3; a solid electrolyte interface reaction layer, which is composed of a chemical bond network formed by in-situ reaction of the second functional group with surface groups of a solid electrolyte or a precursor thereof; the chemical bond network comprises one or more of a covalent bond, a coordination bond or an ionic bond; wherein the chemical bond network comprises a metal element M, and M is a metal element derived from the solid electrolyte, comprising one or more of Li, La, Zr, Ti or Al.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage materials technology, and in particular to an interfacial chemically bonded microporous copper foil current collector, its preparation method, and its application. Background Technology

[0002] Against the backdrop of the booming development of the new energy industry, the research and development of high-performance energy storage and energy conversion devices has become a crucial driving force for industry progress. As a key energy storage carrier, the performance improvement of lithium-ion batteries directly relates to core requirements such as the driving range of new energy vehicles and the usage time of consumer electronics. However, traditional liquid lithium-ion batteries, due to their use of liquid electrolytes, pose safety hazards such as flammability and leakage, and are gradually becoming unable to meet the application requirements of high energy density and high safety. In contrast, all-solid-state lithium batteries, with their inherently high safety and large energy density potential, are considered an important development direction for next-generation battery technology.

[0003] Copper foil, as a key material for the negative electrode current collector in lithium-ion batteries, is an important carrier for active materials and electron conduction. Its structural characteristics and surface properties have a significant impact on the overall battery performance. Although traditional microporous copper foil can improve the loading of active materials to some extent through its porous structure, its surface chemical activity is low, lacking functional groups that can participate in reactions, making it difficult to form a stable chemical bond with the solid electrolyte. Therefore, after loading the solid electrolyte, the interfacial bonding is weak, easily leading to electrolyte shedding and insufficient interfacial stability, making it difficult to effectively solve the key bottlenecks commonly found in solid-state batteries, such as poor interfacial contact and high interfacial impedance. In addition, existing microporous copper foil preparation technologies mostly focus on the control of pore structure, with insufficient attention to the functional design of the copper foil surface, making it difficult to meet the requirements of in-situ loading of solid electrolytes and the construction of stable interfaces.

[0004] For example, patent publication number CN116207292A discloses a microporous mesh copper foil and a method for in-situ construction of a gradient solid electrolyte interface (SEI). This technology generates an SEI layer on the copper foil surface through electrochemical reduction deposition. The SEI components and the copper foil substrate only exhibit van der Waals forces or mechanical intercalation, without forming stable chemical bonds. This results in insufficient interfacial bonding strength. During battery cycling, due to the volume expansion and contraction of lithium, the SEI layer easily peels off or detaches from the copper foil surface. Simultaneously, the interfacial impedance continuously increases with the number of cycles, affecting the battery's fast-charging performance and cycle life. Furthermore, this technology relies on electrolyte decomposition to generate the SEI, and its composition is mainly determined by the electrolyte formulation and electrochemical conditions, making it difficult to controllably design the interfacial structure as needed, such as introducing specific functional groups or constructing specific chemical bonding structures. When this copper foil is applied to oxide solid electrolyte or sulfide solid electrolyte systems, the lack of active sites on the copper foil surface that can react with the solid electrolyte surface makes it difficult to construct a low-interfacial-impedance and stable chemical bridging structure between the copper foil and the solid electrolyte.

[0005] Therefore, there is an urgent need to develop a microporous copper foil preparation technology that combines surface functionalization characteristics with in-situ loading capacity. By using surface chemical bonding, the copper foil can be given a stronger interfacial bond with the solid electrolyte, while achieving in-situ uniform loading of the solid electrolyte. This will provide an effective technical approach to solve the interface problem of solid-state batteries, reduce interfacial impedance and improve interfacial stability, and provide important technical support for the industrial application of all-solid-state lithium batteries. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing an interfacial chemically bonded microporous copper foil current collector, its preparation method, and its application.

[0007] To achieve the above objectives, in a first aspect, the present invention provides an interfacial chemically bonded microporous copper foil current collector, comprising: The microporous copper foil substrate is a rolled copper foil or an electrolytic copper foil with a thickness of 4-12 μm. The substrate has a microporous structure with a pore size of 5-30 μm, a pore depth of 3-10 μm, and a porosity of 20%-60%. The microporous structure is a through-hole and / or a blind hole. A copper surface anchoring layer, wherein the copper surface anchoring layer is composed of bifunctional organic molecules; the bifunctional organic molecules include a first functional group and a second functional group; wherein the first functional group includes one or more of thiol groups -SH or -NH2, which are used to form coordination bonds or covalent bonds with the copper surface, so that the bifunctional organic molecules are anchored on the surface of the microporous copper foil substrate and the inner wall of the microporous structure; the second functional group includes one or more of -COOH, -PO4 or -Si(OR)3. The solid electrolyte interface reaction layer is composed of a chemical bond network formed by the in-situ reaction between the second functional group and the surface groups of the solid electrolyte; the chemical bond network includes one or more of covalent bonds, coordinate bonds, or ionic bonds; wherein the chemical bond network includes a metal element M, which is a metal element derived from the solid electrolyte, including one or more of Li, La, Zr, Ti, or Al.

[0008] Preferably, the solid electrolyte includes one or more of the following: oxide solid electrolyte, sulfide solid electrolyte, or polymer solid electrolyte; The oxide solid electrolyte undergoes an in-situ reaction with the second functional group silyl group -Si(OR)3 of the bifunctional organic molecule. The silyl group hydrolyzes under water or humidity conditions to generate silanol group Si-OH, which undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a Si-OM covalent bond. The oxide solid electrolyte undergoes an in-situ reaction with the second functional group phosphate group -PO4 of the bifunctional organic molecule, and the phosphate group undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a POM covalent bond; The oxide solid electrolyte undergoes an in-situ reaction with the second functional group -COOH of the difunctional organic molecule. The carboxyl group interacts with the metal atom M on the surface of the oxide solid electrolyte through the lone pair electrons on its oxygen atom to form a coordinate bond. The sulfide solid electrolyte undergoes an in-situ reaction with the second functional group phosphate group -PO4 of the bifunctional organic molecule. The phosphate group reacts with Li2S or sulfur-containing species on the surface of the metal ion polymer solid electrolyte to form an ionic bond network through PS-Li chemical bonding. The sulfide solid electrolyte undergoes an in-situ reaction with the second functional group (carboxyl group -COOH) of the bifunctional organic molecule. The carboxyl group then reacts with lithium sulfide (Li₂S) on the surface of the sulfide solid electrolyte in an acid-base reaction to form -COO. - Li + Interface ionic bonds; The sulfide solid electrolyte undergoes an in-situ reaction with the second functional group silyl group -Si(OR)3 of the difunctional organic molecule. The silyl group hydrolyzes under water or humidity conditions to generate silanol group Si-OH, which then undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH formed on the oxide layer of the sulfide solid electrolyte surface to form a Si-OM covalent bond. The polymer solid electrolyte undergoes an in-situ reaction with the second functional group (carboxyl group -COOH) of the bifunctional organic molecule. Under the action of an initiator or crosslinking agent, the carboxyl group undergoes a ring-opening or condensation reaction with a specific functional group on the polymer electrolyte chain segment to form a covalent crosslinked network structure. The specific functional group includes one or more of epoxy, hydroxyl, or amino groups.

[0009] Preferably, the polymer solid electrolyte contains C=C double bond end groups, and the thiol group -SH in the bifunctional organic molecule also functions as a second functional group; The thiol-SH group undergoes radical addition with the C=C double bond end group in the polymer solid electrolyte through a thiol-alkene click reaction, forming a covalent bond structure of thioether bond -SC- at the interface.

[0010] Preferably, the bifunctional organic molecule includes one or more of the following: 3-mercaptopropionic acid, (3-mercaptopropyl)trialkoxysilane, or dopamine or its derivatives grafted with a phosphorylation reagent to form a bifunctional organic molecule. The oxide solid electrolyte includes lithium lanthanum zirconium oxide (LLZO) or lithium aluminum titanium phosphate (LATP). The sulfide solid electrolyte includes lithium germanium phosphide sulfide LGPS or Li6PS5Cl. The polymer solid electrolyte comprises a polymer matrix and a lithium salt, wherein the polymer matrix comprises a polyethylene oxide (PEO)-acrylate polymer, wherein acrylate groups are attached to one or both ends of the PEO chain, and the lithium salt comprises LiTFSI.

[0011] Secondly, embodiments of the present invention provide a method for preparing the interfacial chemically bonded microporous copper foil current collector described in the first aspect above, comprising: S1. Microporous copper foil pretreatment: The copper foil is laser-drilled or chemically etched to form a microporous array structure. Then, it is sequentially cleaned with organic solvent, acid pickled and deionized water to remove oil and natural oxide layer on the surface. After drying, the pretreated microporous copper foil is obtained. S2. Surface functionalization modification treatment: The pretreated microporous copper foil is immersed in a solution containing bifunctional organic molecules, so that the first functional group of the bifunctional organic molecules forms a coordination bond or covalent bond with the copper surface, thereby forming a copper surface anchoring layer on the surface of the microporous copper foil and the inner wall of the microporous structure. S3. In-situ bonding treatment of solid electrolyte: Based on the system of the solid electrolyte material used, select the corresponding bonding route to make the second functional group of the difunctional organic molecule react in-situ with the surface group of the solid electrolyte to form a solid electrolyte interface reaction layer. The solid electrolyte is then bonded to the surface of the microporous copper foil and the inner wall of the microporous structure through the copper surface anchoring layer to obtain the interfacial chemically bonded microporous copper foil current collector.

[0012] Preferably, immersing the pretreated microporous copper foil in a solution containing bifunctional organic molecules specifically includes: The pretreated microporous copper foil is immersed in a solution containing bifunctional organic molecules. By using negative pressure-assisted permeation or ultrasonic-assisted wetting, the solution containing bifunctional organic molecules enters the microporous structure and wets the bottom and walls of the microporous structure.

[0013] Preferably, the selection of the appropriate bonding route based on the system using the solid electrolyte material includes: When using an oxide solid electrolyte, the bonding route is selected with (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule; or, the bonding route is selected with 3-mercaptopropionic acid as the bifunctional organic molecule; or, the bonding route is selected with dopamine or its derivative grafted with a phosphorylating agent to form a bifunctional organic molecule. When using a sulfide solid electrolyte, the bonding route is selected with the difunctional organic molecule (3-mercaptopropyl)trialkoxysilane; or, the bonding route is selected with the difunctional organic molecule 3-mercaptopropionic acid; or, the bonding route is selected with the difunctional organic molecule formed by grafting dopamine or its derivatives with a phosphorylation reagent. When using a polymer solid electrolyte, the bonding route with the difunctional organic molecule (3-mercaptopropyl)trialkoxysilane is selected; or, the bonding route with the difunctional organic molecule 3-mercaptopropionic acid is selected.

[0014] Preferably, when using an oxide solid electrolyte, the bonding route using (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule specifically includes: immersing a microporous copper foil in a mixed solution of ethanol and / or water containing (3-mercaptopropyl)triethoxysilane, adjusting the pH of the solution to 4-5 to obtain a surface-functionalized copper foil; preparing a precursor sol for the oxide solid electrolyte, immersing the surface-functionalized copper foil in the precursor sol, soaking it at 25-60°C for 1-24 hours, then performing a pull-coating, followed by evaporation at 150°C to remove the solvent, and then holding it at 300-600°C for 1-4 hours to allow the silanol group Si-OH to undergo a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a Si-OM covalent bond; preferably, the precursor sol also includes a metal alkoxide; When using an oxide solid electrolyte, the bonding route using 3-mercaptopropionic acid as the bifunctional organic molecule specifically includes: immersing a microporous copper foil in an ethanol solution containing 3-mercaptopropionic acid, wherein the concentration of 3-mercaptopropionic acid in the solution is 0.001-0.05 mol / L, to obtain a copper foil with surface functionalization modification; preparing a precursor sol for the oxide solid electrolyte, immersing the surface functionalized copper foil in the precursor sol, soaking it at 25-60℃ for 1-24 hours, then performing a dip-coating process, subsequently evaporating to remove the solvent at 150℃, and then heat-treating at 300-600℃. During this process, the carboxyl group -COOH of the bifunctional organic molecule coordinates with the metal atom M on the surface of the oxide solid electrolyte through the lone pair electrons on its oxygen atom, thereby forming a -COO-M coordination bond at the interface, achieving chemical bonding between the oxide solid electrolyte and the microporous copper foil; When using an oxide solid electrolyte, the bonding route for selecting a bifunctional organic molecule as a grafted dopamine or its derivative with a phosphorylation reagent specifically includes: dissolving dopamine hydrochloride in a Tris buffer solution and adjusting the pH to 8-9; immersing the microporous copper foil in the solution for self-polymerization deposition to form a polydopamine functional layer on the copper surface; subsequently immersing the copper foil in a solution containing a phosphorylation reagent for a grafting reaction, allowing the active sites on the polydopamine molecule to bind with the phosphorylation reagent, forming a bifunctional organic molecule layer containing phosphate group -PO4 on the copper surface; then immersing the copper foil in the oxide solid electrolyte precursor sol and performing dip-coating and heat treatment, causing the phosphate group -PO4 to undergo a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a POM covalent bond; When using a sulfide solid electrolyte, the bonding route using the bifunctional organic molecule 3-mercaptopropionic acid specifically includes: immersing a microporous copper foil in an ethanol solution containing 3-mercaptopropionic acid, wherein the concentration of 3-mercaptopropionic acid in the solution is 0.001-0.05 mol / L, to obtain a surface-functionalized copper foil; preparing a nanoparticle dispersion of the sulfide solid electrolyte Li6PS5Cl or LGPS; immersing the surface-functionalized copper foil in the dispersion; and using vacuum-assisted filling to allow the sulfide solid electrolyte particles to enter the microporous structure; subsequently, hot-pressing treatment is performed at 100-200 MPa pressure and 25-150℃. During this process, the carboxyl group -COOH of the bifunctional organic molecule reacts with the Li2S on the surface of the sulfide solid electrolyte to generate -COO. - Li + Interfacial ionic bonds are formed between the sulfide solid electrolyte and the microporous copper foil, thereby creating an interfacial ionic bond network. When using a sulfide solid electrolyte, the bonding route using (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule specifically includes: immersing a microporous copper foil in a mixed solution of ethanol and / or water containing (3-mercaptopropyl)triethoxysilane, adjusting the pH of the solution to 4-5 to obtain a surface-functionalized copper foil; preparing a nanoparticle dispersion of the sulfide solid electrolyte Li6PS5Cl or LGPS; immersing the surface-functionalized microporous copper foil in the dispersion, and using negative pressure-assisted permeation or vacuum-assisted filling to allow the sulfide solid electrolyte particles to enter the microporous electrolyte. The porous structure is filled inside and covers the surface of the microporous copper foil. Then, hot pressing is performed under a pressure of 100-200 MPa and a temperature of 25-150°C to compact the sulfide solid electrolyte particles in the microporous structure and form a dense contact. During this process, the silyl group of the bifunctional organic molecule, silyl-Si(OR)3, hydrolyzes under water or humidity conditions to generate silanol group Si-OH, which undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH formed on the oxide layer of the sulfide solid electrolyte surface to form a Si-OM covalent bond, thereby forming a stable interfacial chemical bond structure between the microporous copper foil and the sulfide solid electrolyte. When using a sulfide solid electrolyte, the specific bonding route for selecting a difunctional organic molecule as the grafted dopamine or its derivative with a phosphorylation reagent includes: first, dissolving dopamine hydrochloride in a Tris buffer solution and adjusting the pH to 8-9; immersing the microporous copper foil in this solution for self-polymerization deposition to form a polydopamine functional layer on the copper surface; subsequently, immersing the copper foil in a solution containing a phosphorylation reagent for a grafting reaction, allowing the active sites on the polydopamine molecules to bind with the phosphorylation reagent, forming a layer on the copper surface. A bifunctional organic molecular layer containing phosphate group -PO4 is formed. Then, the copper foil is immersed in a nanoparticle dispersion of sulfide solid electrolyte Li6PS5Cl or LGPS, and the sulfide solid electrolyte particles are introduced into the microporous structure by vacuum-assisted filling. Subsequently, hot pressing is performed under a pressure of 100-200MPa and a temperature of 25-150℃. During this process, the phosphate group -PO4 reacts with the sulfur-containing species on the surface of the sulfide solid electrolyte to form PS-Li chemical bonds, thereby constructing a stable interfacial ionic bond network. When using a polymer solid electrolyte, the bonding route using 3-mercaptopropionic acid as the bifunctional organic molecule specifically includes: immersing a microporous copper foil in an ethanol solution containing 3-mercaptopropionic acid, wherein the concentration of 3-mercaptopropionic acid in the solution is 0.001-0.05 mol / L, to obtain a surface-functionalized copper foil; preparing a PEO-based polymer solid electrolyte precursor solution containing reactive end groups, and coating it onto the surface and interior of the microporous structure of the surface-functionalized copper foil, wherein the PEO-based polymer is a PEO-acrylate polymer containing lithium salt LiTFSI; subsequently, an in-situ polymerization reaction is carried out under ultraviolet light or thermal initiation conditions, wherein the carboxyl-COOH group can undergo hydrogen bonding or coordination with the hydroxyl or ether oxygen in the polymer chain segment, thereby forming a chemical bond structure at the interface; When using a polymer solid electrolyte, the bonding route using (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule specifically includes: the thiol-SH group in the bifunctional organic molecule simultaneously functions as the second functional group; immersing a microporous copper foil in a mixed solution of ethanol and / or water containing (3-mercaptopropyl)triethoxysilane, adjusting the pH of the solution to 4-5, to obtain a copper foil with surface functionalization modification; preparing a PEO-based polymer solid electrolyte precursor solution containing reactive end groups, and coating it onto the surface and interior of the microporous structure of the surface-functionalized microporous copper foil, wherein the PEO-based polymer is a PEO-acrylate polymer containing lithium salt LiTFSI; subsequently, an in-situ polymerization reaction is carried out under ultraviolet light or thermal initiation conditions, causing the thiol-SH group in the bifunctional organic molecule to undergo a free radical addition reaction with the C=C double bond of the polymer solid electrolyte chain segment end group, forming a -SC-thioether covalent bond at the interface, thereby constructing a covalent cross-linked interface structure between the polymer solid electrolyte and the microporous copper foil.

[0015] Thirdly, embodiments of the present invention provide a negative electrode, comprising the interfacial chemically bonded microporous copper foil current collector described in the first aspect above.

[0016] Fourthly, embodiments of the present invention provide a solid-state lithium battery, including the negative electrode described in the third aspect above.

[0017] The interfacial chemically bonded microporous copper foil current collector provided in this invention constructs a copper surface anchoring layer formed by bifunctional organic molecules on the surface of the microporous copper foil. This allows the first functional group to form coordination or covalent bonds with the copper surface, thereby achieving stable anchoring of the organic molecules on the copper surface and the inner wall of the microporous structure. Simultaneously, the second functional group undergoes an in-situ reaction with the surface groups of the solid electrolyte, constructing a chemical bond network composed of covalent, coordination, or ionic bonds between the copper foil and the solid electrolyte. This achieves chemical bonding between the microporous copper foil and the solid electrolyte, significantly improving the interfacial bonding strength and fundamentally avoiding the interfacial peeling problem caused by volume changes during cycling in traditional physical interfacial bonding. This results in a low-impedance, stable solid-solid interface structure. Meanwhile, this invention provides a controllable design of bifunctional organic molecules, enabling the interfacial reaction to be matched to different types of solid electrolytes. For example, it allows interfacial reactions with oxide, sulfide, or polymer solid electrolytes via Si-OM, POM covalent bonds, coordination bonds, or ionic bonds, thereby achieving controllable construction of the interfacial structure. This allows the microporous copper foil to be adapted to various solid electrolyte materials, improving the versatility and interfacial stability of the material system. Furthermore, this invention utilizes the three-dimensional pore structure of the microporous copper foil and uniformly functionalizes the inner wall of the microporous structure with bifunctional molecules, forming stable interfacial reaction sites on both the copper foil surface and inside the micropores. This achieves uniform loading and interfacial bonding of the solid electrolyte within the microporous structure, fully leveraging the high specific surface area advantage of the microporous structure. During charging and discharging, it induces uniform lithium deposition and stripping in three-dimensional space, reducing local current density, effectively suppressing the generation and growth of lithium dendrites, and improving the cycle stability and safety of the battery. Attached Figure Description

[0018] Figure 1 A flowchart illustrating the preparation method of the interfacial chemically bonded microporous copper foil current collector provided in this embodiment of the invention. Detailed Implementation

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0020] This invention provides an interfacial chemically bonded microporous copper foil current collector and its preparation method.

[0021] The interfacial chemically bonded microporous copper foil current collector proposed in this invention comprises: The microporous copper foil substrate is a rolled copper foil or an electrolytic copper foil with a thickness of 4-12 μm. The substrate has a microporous structure with a pore size of 5-30 μm, a pore depth of 3-10 μm, and a porosity of 20%-60%. The microporous structure is a through-hole and / or a blind hole. A copper surface anchoring layer, wherein the copper surface anchoring layer is composed of bifunctional organic molecules; the bifunctional organic molecules include a first functional group and a second functional group; wherein the first functional group includes one or more of thiol groups -SH or -NH2, which are used to form coordination bonds or covalent bonds with the copper surface, so that the bifunctional organic molecules are anchored on the surface of the microporous copper foil substrate and the inner wall of the microporous structure; the second functional group includes one or more of -COOH, -PO4 or -Si(OR)3. The solid electrolyte interface reaction layer is composed of a chemical bond network formed by the in-situ reaction between the second functional group and the surface groups of the solid electrolyte; the chemical bond network includes one or more of covalent bonds, coordinate bonds, or ionic bonds; wherein the chemical bond network includes a metal element M, which is a metal element derived from the solid electrolyte, including one or more of Li, La, Zr, Ti, or Al.

[0022] Solid electrolytes can include one or more of the following: oxide solid electrolytes, sulfide solid electrolytes, or polymer solid electrolytes. In practical applications, the selected bifunctional organic molecule can be determined according to the specific type of solid electrolyte used in conjunction with the copper foil substrate.

[0023] The binding mechanism between the first functional group and Cu is as follows: The thiol group undergoes chemisorption with unsaturated metal sites on the copper surface via the S atom, forming a Cu-S coordination covalent bond. When the -SH group of an organic molecule comes into contact with the copper surface, its SH bond dissociates: R SH→R S +H + The lone pair electrons of the sulfur atom interact with the unsaturated d orbitals on the copper surface: R S +Cu→Cu S R forms Cu–S bonds.

[0024] The amino group primarily binds to copper through coordination. The nitrogen atom has a lone pair of electrons: NH₂. This lone pair can be donated to unoccupied orbitals on the copper surface, forming Cu←NH₂. In other words, an N→Cu coordination bond is formed between the lone pair of electrons on the N atom and the metal site on the copper surface.

[0025] The binding mechanism between the second functional group and the solid electrolyte is as follows: The second functional group of the bifunctional organic molecule, silyl group -Si(OR)3, undergoes an in-situ reaction with the oxide solid electrolyte. The silyl group hydrolyzes under water or humidity conditions to generate silanol group Si-OH, which undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a Si-OM covalent bond. The second functional group of the bifunctional organic molecule, the phosphate group -PO4, reacts in situ with the oxide solid electrolyte. The phosphate group undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a POM covalent bond. The second functional group of the bifunctional organic molecule, the carboxyl group -COOH, undergoes an in-situ reaction with the oxide solid electrolyte. The carboxyl group interacts with the metal atom M on the surface of the oxide solid electrolyte through the lone pair electrons on its oxygen atom, forming a coordinate bond. The sulfide solid electrolyte reacts in situ with the second functional group of the bifunctional organic molecule, phosphate group -PO4, and the phosphate group reacts with Li2S or sulfur-containing species on the surface of the metal ion polymer solid electrolyte to form an ionic bond network through PS-Li chemical bonding. The second functional group, the carboxyl group (-COOH), of the bifunctional organic molecule undergoes an in-situ reaction with the sulfide solid electrolyte. The carboxyl group then reacts with lithium sulfide (Li₂S) on the surface of the sulfide solid electrolyte in an acid-base reaction, forming -COO. - Li + Interface ionic bonds; The second functional group of the bifunctional organic molecule, silyl group -Si(OR)3, undergoes an in-situ reaction with the sulfide solid electrolyte. The silyl group hydrolyzes under water or humidity conditions to generate silanol group Si-OH, which then undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH formed on the oxide layer of the sulfide solid electrolyte surface to form a Si-OM covalent bond. The second functional group of the bifunctional organic molecule, the carboxyl group -COOH, reacts in situ with the polymer solid electrolyte. Under the action of an initiator or crosslinking agent, the carboxyl group undergoes ring-opening or condensation reactions with specific functional groups on the polymer electrolyte chain segment to form a covalent crosslinked network structure. The specific functional groups include one or more of epoxy, hydroxyl, or amino groups.

[0026] Furthermore, in the case of polymer solid electrolytes containing C=C double bond end groups, such as polyethylene oxide (PEO)-acrylate polymers, the thiol-SH in the bifunctional organic molecule can also be used as a second functional group; the thiol-SH and the C=C double bond end groups in the polymer solid electrolyte undergo free radical addition through a thiol-alkene click reaction to form a covalent bond structure of thioether bond -SC- at the interface.

[0027] In specific embodiments of the present invention, the bifunctional organic molecules used include: 3-mercaptopropionic acid, (3-mercaptopropyl)trialkoxysilane, or dopamine or its derivatives grafted with a phosphorylation reagent to form a bifunctional organic molecule; the oxide solid electrolyte includes lithium lanthanum zirconium oxide (LLZO) or lithium aluminum titanium phosphate (LATP); the sulfide solid electrolyte includes lithium germanium phosphorus sulfide (LGPS) or Li6PS5Cl; the polymer solid electrolyte includes a polymer matrix and a lithium salt, wherein the polymer matrix is ​​a polyethylene oxide (PEO)-acrylate polymer, wherein the acrylate groups are attached to one or both ends of the PEO chain, and the lithium salt includes LiTFSI.

[0028] It is understood that the above are merely specific examples provided to illustrate the technical solution of the present invention. However, the present invention is not limited to the specific types mentioned above. As long as the organic molecule simultaneously contains a first functional group capable of bonding with the copper surface and a second functional group capable of bonding with the solid electrolyte surface, and is able to construct an interface anchoring structure between the copper surface and the solid electrolyte, it falls within the protection scope of the technical solution of the present invention.

[0029] The interfacial chemically bonded microporous copper foil current collector proposed in this invention can be obtained by the following preparation method. Figure 1 The method for preparing the interfacial chemically bonded microporous copper foil current collector provided in this embodiment of the invention mainly includes the following steps: Step 110: Microporous copper foil pretreatment: The copper foil is laser-drilled or chemically etched to form a microporous array structure. Then, it is sequentially cleaned with organic solvent, acid pickled and deionized water to remove oil and the natural oxide layer on the surface. After drying, the pretreated microporous copper foil is obtained.

[0030] Specifically, copper foil is laser-drilled or chemically etched to form a microporous array structure, with pore size controlled at 5–30 μm, pore depth at 3–10 μm, and porosity at approximately 20%–60%. After forming the microporous array, the copper foil is sequentially immersed in organic solvents for ultrasonic cleaning: first in acetone for 10–20 minutes, then in anhydrous ethanol for 10–20 minutes, to thoroughly remove oil and processing residues from the pore walls and surface. Subsequently, the copper foil is immersed in 3–10 wt% dilute hydrochloric acid for ultrasonic treatment for 5–10 minutes to remove the natural oxide layer and impurity deposits on the surface. After cleaning, it is rinsed 3–5 times with deionized water, approximately 1–2 minutes each time, to ensure that acid pickling residues are fully removed. Finally, the copper foil is placed in a vacuum drying oven at 50–70°C for 1–3 hours until the copper foil surface is completely dry, clean, and free of oxide layer, thus obtaining the pretreated microporous copper foil for subsequent surface functionalization.

[0031] Step 120: Surface functionalization modification treatment: Immerse the pretreated microporous copper foil in a solution containing bifunctional organic molecules, so that the first functional group of the bifunctional organic molecules forms a coordination bond or covalent bond with the copper surface, thereby forming a copper surface anchoring layer on the surface of the microporous copper foil and the inner wall of the microporous structure.

[0032] Specifically, the pretreated microporous copper foil is immersed in a solution containing bifunctional organic molecules. By using negative pressure-assisted osmosis or ultrasonic-assisted wetting, the solution containing bifunctional organic molecules enters the microporous structure and wets the bottom and walls of the microporous structure.

[0033] The specific choice of solution containing bifunctional organic molecules depends on the system of solid electrolyte material used in the next step. This will be explained in detail in the next step.

[0034] The present invention employs negative pressure-assisted functionalization in the preparation process, which can achieve uniform modification of the bottom and walls of micropores, resulting in uniform lithium deposition in the deep part of the micropores, giving full play to the specific surface area advantage of the three-dimensional current collector, and improving the rate performance of the electrode material.

[0035] Step 130: In-situ bonding treatment of solid electrolyte: Based on the system of the solid electrolyte material used, select the corresponding bonding route to make the second functional group of the bifunctional organic molecule react in-situ with the surface group of the solid electrolyte to form a solid electrolyte interface reaction layer. The solid electrolyte is then bonded to the surface of the microporous copper foil and the inner wall of the microporous structure through the copper surface anchoring layer to obtain the interfacial chemically bonded microporous copper foil current collector.

[0036] Specifically, when using an oxide solid electrolyte, the bonding route is selected with (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule; or, the bonding route is selected with 3-mercaptopropionic acid as the bifunctional organic molecule; or, the bonding route is selected with dopamine or its derivative grafted with a phosphorylating agent to form a bifunctional organic molecule.

[0037] Specifically, when using an oxide solid electrolyte, the bonding route using (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule includes: immersing a microporous copper foil in a mixed solution of ethanol and / or water containing (3-mercaptopropyl)triethoxysilane, adjusting the pH of the solution to 4-5 to obtain a surface-functionalized copper foil; preparing a precursor sol for the oxide solid electrolyte, immersing the surface-functionalized copper foil in the precursor sol, soaking it at 25-60℃ for 1-24 hours, then performing a pull-coating, followed by evaporation at 150℃ to remove the solvent, and then holding it at 300-600℃ for 1-4 hours to allow the silanol group Si-OH to undergo a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a Si-OM covalent bond; preferably, the precursor sol also includes a metal alkoxide.

[0038] When using an oxide solid electrolyte, the bonding route using 3-mercaptopropionic acid as the bifunctional organic molecule specifically includes: immersing a microporous copper foil in an ethanol solution containing 3-mercaptopropionic acid, wherein the concentration of 3-mercaptopropionic acid in the solution is 0.001-0.05 mol / L, to obtain a copper foil with surface functionalization modification; preparing a precursor sol for the oxide solid electrolyte, immersing the surface functionalized copper foil in the precursor sol, soaking it at 25-60℃ for 1-24 hours, then performing a dip-coating process, subsequently evaporating to remove the solvent at 150℃, and then heat-treating at 300-600℃. During this process, the carboxyl group -COOH of the bifunctional organic molecule coordinates with the metal atom M on the surface of the oxide solid electrolyte through the lone pair electrons on its oxygen atom, thereby forming a -COO-M coordination bond at the interface, achieving chemical bonding between the oxide solid electrolyte and the microporous copper foil.

[0039] When using an oxide solid electrolyte, the bonding route for selecting a bifunctional organic molecule as a grafted dopamine or its derivative with a phosphorylation reagent specifically includes: dissolving dopamine hydrochloride in a Tris buffer solution and adjusting the pH to 8-9; immersing the microporous copper foil in the solution for self-polymerization deposition to form a polydopamine functional layer on the copper surface; subsequently immersing the copper foil in a solution containing a phosphorylation reagent for a grafting reaction, allowing the active sites on the polydopamine molecule to bind with the phosphorylation reagent, forming a bifunctional organic molecule layer containing phosphate group -PO4 on the copper surface; then immersing the copper foil in the oxide solid electrolyte precursor sol and performing dip-coating and heat treatment, causing the phosphate group -PO4 to undergo a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a POM covalent bond.

[0040] When using a sulfide solid electrolyte, the bonding route is selected with the difunctional organic molecule as (3-mercaptopropyl)trialkoxysilane; or, the bonding route is selected with the difunctional organic molecule as 3-mercaptopropionic acid; or, the bonding route is selected with the difunctional organic molecule formed by grafting dopamine or its derivatives with a phosphorylating agent.

[0041] Specifically, when using a sulfide solid electrolyte, the bonding route using the bifunctional organic molecule 3-mercaptopropionic acid includes: immersing a microporous copper foil in an ethanol solution containing 3-mercaptopropionic acid at a concentration of 0.001-0.05 mol / L to obtain a surface-functionalized copper foil; preparing a nanoparticle dispersion of the sulfide solid electrolyte Li6PS5Cl or LGPS; immersing the surface-functionalized copper foil in the dispersion; and using vacuum-assisted filling to allow the sulfide solid electrolyte particles to enter the microporous structure; subsequently, hot-pressing treatment at 100-200 MPa and 25-150°C; during this process, the carboxyl group -COOH of the bifunctional organic molecule reacts with the Li2S on the surface of the sulfide solid electrolyte to generate -COO. - Li + Interfacial ionic bonds are formed, thereby creating an interfacial ionic bond network between the sulfide solid electrolyte and the microporous copper foil.

[0042] When using a sulfide solid electrolyte, the bonding route using (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule specifically includes: immersing a microporous copper foil in a mixed solution of ethanol and / or water containing (3-mercaptopropyl)triethoxysilane, adjusting the pH of the solution to 4-5 to obtain a surface-functionalized copper foil; preparing a nanoparticle dispersion of the sulfide solid electrolyte Li6PS5Cl or LGPS; immersing the surface-functionalized microporous copper foil in the dispersion, and using negative pressure-assisted permeation or vacuum-assisted filling to allow the sulfide solid electrolyte particles to enter the microporous electrolyte. The porous structure is filled and covers the surface of the microporous copper foil. Then, hot pressing is performed under a pressure of 100-200 MPa and a temperature of 25-150°C to compact the sulfide solid electrolyte particles in the microporous structure and form a dense contact. During this process, the silyl group of the bifunctional organic molecule, silane-Si(OR)3, hydrolyzes under water or humidity conditions to generate silanol group Si-OH, which undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH formed on the oxide layer of the sulfide solid electrolyte surface to form a Si-OM covalent bond, thereby forming a stable interfacial chemical bond structure between the microporous copper foil and the sulfide solid electrolyte.

[0043] When using a sulfide solid electrolyte, the specific bonding route for selecting a difunctional organic molecule as the grafted dopamine or its derivative with a phosphorylation reagent includes: first, dissolving dopamine hydrochloride in a Tris buffer solution and adjusting the pH to 8-9; immersing the microporous copper foil in this solution for self-polymerization deposition to form a polydopamine functional layer on the copper surface; subsequently, immersing the copper foil in a solution containing a phosphorylation reagent for a grafting reaction, allowing the active sites on the polydopamine molecules to bind with the phosphorylation reagent, forming a layer on the copper surface. A bifunctional organic molecular layer containing phosphate group -PO4 is formed. Then, the copper foil is immersed in a nanoparticle dispersion of sulfide solid electrolyte Li6PS5Cl or LGPS, and the sulfide solid electrolyte particles are introduced into the microporous structure by vacuum-assisted filling. Subsequently, hot pressing is performed under a pressure of 100-200MPa and a temperature of 25-150℃. During this process, the phosphate group -PO4 reacts with the sulfur-containing species on the surface of the sulfide solid electrolyte to form PS-Li chemical bonds, thereby constructing a stable interfacial ionic bond network.

[0044] When using a polymer solid electrolyte, the bonding route with the difunctional organic molecule (3-mercaptopropyl)trialkoxysilane is selected; or, the bonding route with the difunctional organic molecule 3-mercaptopropionic acid is selected.

[0045] Specifically, when using a polymer solid electrolyte, the bonding route using 3-mercaptopropionic acid as the bifunctional organic molecule includes: immersing a microporous copper foil in an ethanol solution containing 3-mercaptopropionic acid, wherein the concentration of 3-mercaptopropionic acid in the solution is 0.001-0.05 mol / L, to obtain a surface-functionalized copper foil; preparing a PEO-based polymer solid electrolyte precursor solution containing reactive end groups, and coating it onto the surface and interior of the microporous structure of the surface-functionalized copper foil, wherein the PEO-based polymer is a PEO-acrylate polymer containing lithium salt LiTFSI; subsequently, an in-situ polymerization reaction is carried out under ultraviolet light or thermal initiation conditions, wherein the carboxyl-COOH group can undergo hydrogen bonding or coordination with the hydroxyl or ether oxygen in the polymer chain segment, thereby forming a chemical bond structure at the interface.

[0046] When using a polymer solid electrolyte, the bonding route using (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule specifically includes: the thiol-SH group in the bifunctional organic molecule simultaneously functions as the second functional group; immersing a microporous copper foil in a mixed solution of ethanol and / or water containing (3-mercaptopropyl)triethoxysilane, adjusting the pH of the solution to 4-5, to obtain a copper foil with surface functionalization modification; preparing a PEO-based polymer solid electrolyte precursor solution containing reactive end groups, and coating it onto the surface and interior of the microporous structure of the surface-functionalized microporous copper foil, wherein the PEO-based polymer is a PEO-acrylate polymer containing lithium salt LiTFSI; subsequently, an in-situ polymerization reaction is carried out under ultraviolet light or thermal initiation conditions, causing the thiol-SH group in the bifunctional organic molecule to undergo a free radical addition reaction with the C=C double bond of the polymer solid electrolyte chain segment end group, forming a -SC-thioether covalent bond at the interface, thereby constructing a covalent cross-linked interface structure between the polymer solid electrolyte and the microporous copper foil.

[0047] This invention achieves atomic-level interfacial connection between copper foil and solid electrolyte by constructing a bifunctional organic molecule anchoring layer on the surface of microporous copper foil and forming a chemically bonded interfacial reaction layer with the solid electrolyte. This significantly improves upon the shortcomings of traditional physical interfacial bonding and achieves significant technical advancements in the following aspects.

[0048] Compared to existing technologies where the SEI layer and copper foil rely solely on physical adsorption (peel strength <0.1 N / cm), this invention achieves a peel strength >5 N / cm (180° peel test) by forming a stable anchoring interface through Cu-S or N→Cu chemical bonds, resulting in a significant improvement in interfacial bonding strength. This is because the bond energy of the chemical bonds (Cu–S approximately 274 kJ / mol) is much higher than that of van der Waals forces (<10 kJ / mol), ensuring that the interface does not peel off under high volumetric strain conditions. Simultaneously, due to the enhanced adhesion of the solid electrolyte, the interfacial chemically bonded microporous copper foil current collector structure of this invention can be applied in ultra-thin solid electrolytes ≤10 μm. This invention can achieve an ultra-thin solid electrolyte layer ≤10 μm without peel risk, increasing the battery's energy density by approximately 15%-25%.

[0049] The initial interface resistance of this invention is only 4-8 Ω·cm 2 It remains <12Ω·cm after 500 cycles. 2 Compared to the initial 15-25 Ω·cm of existing technology 2 After 100 cycles, the Ω·cm value is 50-80. 2 The significant increase in [the specific characteristic] results in a substantial reduction in interfacial impedance and stable cycling performance, with a reduction exceeding 70%. This is because chemical bonding eliminates interfacial porosity, provides continuous lithium-ion transport channels, and maintains interfacial composition stability without the accumulation of side reactions.

[0050] This invention forms a multi-layer integrated structure of copper foil, anchoring layer, interface reaction layer, and solid electrolyte body, which has conformal coverage characteristics in micron-level three-dimensional channels, and can take into account high energy density, low impedance and interface stability, providing key technical support for the industrialization of all-solid-state batteries.

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0052] Example 1 In this embodiment, a rolled copper foil substrate is used, and 3-mercaptopropionic acid (MPA) is used to achieve surface functionalization. The oxide solid electrolyte LLZO is bonded in situ through a sol-gel process.

[0053] 1. Material preparation Copper foil: Rolled copper foil, 8μm thick, 99.9% pure; Micropore fabrication: Ultraviolet laser drilling was used to prepare blind hole structures with a diameter of 15μm, a depth of 8μm, a spacing of 25μm, and a porosity of approximately 28%.

[0054] Functionalizing reagent: 3-mercaptopropionic acid (MPA, Sigma-Aldrich, 99% purity) was prepared into a 10 mM MPA@ethanol solution, and the pH was adjusted to 5.0 with dilute hydrochloric acid to obtain a mixed solution of functionalizing reagent.

[0055] Solid electrolyte precursor sol: LLZO sol was prepared by dissolving lithium acetate, lanthanum nitrate, and zirconium propoxide in ethylene glycol monomethyl ether at a stoichiometric ratio (Li:La:Zr = 7.7:3:2, with 10% lithium in excess to compensate for high-temperature volatilization loss). Acetylacetone was added as a complexing agent (molar ratio to metal ions 1:1), and the mixture was stirred for 1 hour to ensure thorough mixing. Subsequently, deionized water (molar ratio of water to metal ions 5:1) was added to promote the hydrolysis reaction, and the mixture was stirred for another 2 hours to obtain a pale yellow transparent LLZO precursor sol with a concentration of 0.3 mol / L.

[0056] 2. Preparation process Step 1: Pretreatment of microporous copper foil The microporous copper foil was cut into 5cm×5cm sizes and ultrasonically cleaned in acetone and anhydrous ethanol for 15 minutes in sequence to thoroughly remove oil stains. Then it was immersed in 5wt% dilute hydrochloric acid and ultrasonically cleaned for 5 minutes to remove the surface oxide layer. After rinsing with deionized water 3 times and blowing dry with nitrogen, it was placed in a vacuum drying oven at 60℃ for 2 hours to ensure that the copper foil surface was clean and free of oxidation.

[0057] Step 2: Surface functionalization modification Preparation of functionalization reagents: Pretreated copper foil was immersed in the solution and placed in a negative pressure chamber where a vacuum of -0.08 MPa was applied for 10 minutes. The vacuum was then released to allow the solution to fully fill the micropores. This process was repeated three times to ensure uniform modification of the pore bottom. Subsequently, the foil was soaked at 25°C and atmospheric pressure for 12 hours to anchor the bifunctional molecules. After removal, the foil was ultrasonically cleaned three times with anhydrous ethanol to remove unbound physically adsorbed molecules, and then dried with nitrogen.

[0058] Step 3: In-situ bonding and characterization of LLZO The functionalized copper foil was immersed in LLZO precursor sol and coated three times at a pulling speed of 2 mm / s. After drying at 80℃ for 30 min to remove the solvent, it was then heat-treated according to a programmed temperature increase: increasing to 150℃ at 2℃ / min and holding for 1 h, then increasing to 600℃ at 5℃ / min and holding for 2 h to complete the crystallization and in-situ bonding reaction, forming a solid electrolyte interface reaction layer. The functional groups and modification effects were verified using X-ray photoelectron spectroscopy (XPS), contact angle measurement, and energy dispersive spectroscopy (EDS line scan). The bonding mechanism was further verified using Fourier transform infrared spectroscopy (FTIR) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Specific characterization results and process parameters are shown in Table 1 below. Table 1 Step 4: Battery Assembly and Performance Testing The prepared integrated electrode was cut into φ12mm discs as working electrodes, lithium sheet was used as counter electrode, Whatman GF / D was used as separator, and the separator was wetted only with 1M LiTFSI in 1,3-dioxolane / ethylene glycol dimethyl ether (DOL / DME) electrolyte to assemble CR2032 coin cells.

[0059] Comparative Example 1: Unfunctionalized microporous copper foil directly coated with LLZ.

[0060] Comparative Example 2: Gradient SEI copper foil coated with LLZO was prepared using the existing technology CN116207292A. On the pretreated copper foil surface, a 5-10 nm Li2O-rich underlayer was first deposited at room temperature by magnetron sputtering. Then, the temperature was raised to 60°C to co-deposit Li and LLZO to form a 20-50 nm mixed middle layer. Finally, a 10-20 nm Li3N-rich surface layer was formed by deep nitriding at 150-200°C for 10-30 minutes. The gradient was then completed by annealing at 80-120°C for 1-2 hours.

[0061] The core performance test results of Example 1, Comparative Example 1, and Comparative Example 2 are shown in Table 2 below: Table 2 As can be seen, the interfacial chemically bonded microporous copper foil of Example 1 significantly improved the interfacial bonding force, reduced the impedance, enhanced the cycling stability, and achieved a high capacity retention rate, which is significantly better than the comparative example.

[0062] Example 2 This embodiment uses a rolled copper foil substrate and (3-mercaptopropyl)triethoxysilane (MPTES) for surface functionalization, adapted to the oxide solid electrolyte LATP.

[0063] 1. Material preparation Copper foil: Rolled copper foil, 8μm thick, 99.9% pure; Micropore fabrication: Ultraviolet laser drilling was used to prepare blind hole structures with a diameter of 15μm, a depth of 8μm, a spacing of 25μm, and a porosity of approximately 28%.

[0064] Functionalizing reagent: (3-mercaptopropyl)triethoxysilane (MPTES), prepared as (3-mercaptopropyl)triethoxysilane (MPTES):ethanol:water = 5:90:5 (volume ratio), pH adjusted to 4.5 with glacial acetic acid.

[0065] Solid electrolyte LATP precursor sol: LATP sol was prepared by dissolving tetrabutyl titanate, aluminum nitrate, and lithium acetate in ethylene glycol methyl ether at a stoichiometric ratio (Li:Al:Ti:P = 1.3:0.3:1.7:3), adding triethyl phosphate as a phosphorus source, and stirring for 2 hours to obtain a transparent sol with a concentration of 0.5 mol / L.

[0066] 2. Preparation process Step 1: Pretreatment of microporous copper foil is the same as in Example 1.

[0067] Step 2: Surface functionalization modification Prepare functionalizing reagents. Immerse the pretreated copper foil in the solution and soak at 40℃ for 6 hours. Use negative pressure to assist in the permeation to ensure uniform micropore modification.

[0068] Step 3: LATP in situ bonding and characterization Using LATP (Li 1.3 Al 0.3 Ti 1.7 (PO4)3) The precursor sol was used to coat the functionalized copper foil by immersion in the sol-gel method, and crystallization and bonding were achieved by heat treatment at 500℃. The active hydroxyl groups on the LATP surface are mainly located at Ti sites. Therefore, the main bonding mechanism is that the -Si-OH generated by the hydrolysis of MPTES condenses with the Ti-OH on the LATP surface to form Si-O-Ti covalent bonds.

[0069] Step 4: Battery Assembly and Performance Testing The button cells were assembled according to the method in Example 1, and the test results are shown in Table 3 below: Table 3 Example 3 This embodiment uses a rolled copper foil substrate and employs dopamine hydrochloride combined with a phosphorylation reagent to achieve surface functionalization, adapting to the oxide solid electrolyte LATP.

[0070] 1. Material preparation Copper foil: Rolled copper foil, 8μm thick, 99.9% pure; Micropore fabrication: Ultraviolet laser drilling was used to prepare blind hole structures with a diameter of 15μm, a depth of 8μm, a spacing of 25μm, and a porosity of approximately 28%.

[0071] Functionalizing reagents: dopamine hydrochloride (PDA) + phosphorylation reagent (POCl3). PDA was prepared as 2 mg / mL dopamine Tris buffer (pH 8.5), and POCl3 was prepared as 10 mM POCl3@acetonitrile solution.

[0072] Solid electrolyte precursor: LATP sol, tetrabutyl titanate, aluminum nitrate and lithium acetate were dissolved in ethylene glycol methyl ether in a stoichiometric ratio (Li:Al:Ti:P = 1.3:0.3:1.7:3), and triethyl phosphate was added as a phosphorus source. After stirring for 2 hours, a transparent sol with a concentration of 0.5 mol / L was obtained.

[0073] 2. Preparation process Step 1: Pretreatment of microporous copper foil is the same as in Example 1.

[0074] Step 2: Surface functionalization modification Preparation of functionalization reagents. The pretreated copper foil was immersed in 2 mg / mL dopamine Tris buffer (pH 8.5) for 6 h to form a polydopamine anchoring layer. After removal, it was rinsed with deionized water and dried under nitrogen. Then it was immersed in 10 mM POCl3@acetonitrile solution and reacted at 40 °C for 4 h to complete phosphorylation and introduce the -PO4 functional group. After removal, it was rinsed with acetonitrile and dried under nitrogen.

[0075] Step 3: LATP in situ bonding and characterization Functionalized copper foil was immersed in LATP (Li 1.3 Al 0.3 Ti 1.7 (PO4)3) precursor sol was coated three times at a pulling speed of 1 mm / s; the solvent was removed by drying at 120℃ for 30 min, and then the temperature was increased to 400℃ at 2℃ / min and kept for 1 h to complete the LATP crystallization and in-situ bonding reaction, forming a solid electrolyte interface reaction layer with PO-Al / PO-Ti covalent bonds on the copper foil surface.

[0076] Step 4: Battery Assembly and Performance Testing The button cells were assembled according to the method in Example 1, and the test results are shown in Table 4 below: Table 4 Example 4 This embodiment uses a rolled copper foil substrate and 3-mercaptopropionic acid to achieve surface functionalization, and is adapted to the sulfide solid electrolyte Li6PS5Cl.

[0077] 1. Material preparation Copper foil: Rolled copper foil, 8μm thick, 99.9% pure; Micropore fabrication: Ultraviolet laser drilling was used to prepare blind hole structures with a diameter of 15μm, a depth of 8μm, a spacing of 25μm, and a porosity of approximately 28%.

[0078] Functionalizing reagent: 3-mercaptopropionic acid (MPA, Sigma-Aldrich, 99% purity) was prepared into a 10 mM MPA@ethanol solution, and the pH was adjusted to 5.0 with dilute hydrochloric acid to obtain a mixed solution of functionalizing reagent.

[0079] The sulfide solid electrolyte, Li6PS5Cl, was prepared into nanoparticles by high-energy ball milling and dispersed in anhydrous acetonitrile at a concentration of 10 mg / mL.

[0080] 2. Preparation process Step 1: Pretreatment of microporous copper foil is the same as in Example 1.

[0081] Step 2: Surface functionalization modification The pretreated microporous copper foil was immersed in a 0.01 mol / L ethanol solution of 3-mercaptopropionic acid and soaked at 40°C for 4 hours. This allowed 3-mercaptopropionic acid molecules to be anchored to the copper surface through the chemical adsorption of their thiol groups (-SH), forming a self-assembled monolayer. After removal, the foil was rinsed with anhydrous ethanol to remove excess molecules from the physical adsorption and then dried with nitrogen.

[0082] Step 3: In-situ bonding and forming of the Li6PS5Cl electrolyte layer The functionalized copper foil was immersed in a Li6PS5Cl nanoparticle dispersion and allowed to stand for 10 minutes before being removed. Vacuum-assisted filling was then performed, with the pressure evacuated to -0.1 MPa and maintained for 15 minutes to ensure thorough wetting and filling of the micropores. Subsequently, hot-pressing was carried out under an argon atmosphere, with the pressure controlled at 150 MPa and the temperature at 80℃, and the temperature and pressure maintained for 30 minutes. During this process, the carboxyl group (-COOH) at the terminal of the 3-mercaptopropionic acid molecule reacts with the Li2S enriched on the surface of the Li6PS5Cl particles in an acid-base reaction, generating -COO-Li. + Interfacial ionic bonds. Due to the unique sulfogermanium sulfide structure and Cl-doped surface defects of Li6PS5Cl, its surface is rich in reactive Li2S sites, thus forming a continuous and dense three-dimensional interfacial ionic bond network that firmly anchors the electrolyte layer to the copper foil surface.

[0083] Step 4: Battery Assembly and Performance Testing The button cells were assembled according to the method in Example 1, and the test results are shown in Table 5 below: Table 5 Example 5 This embodiment uses a rolled copper foil substrate and (3-mercaptopropyl)triethoxysilane (MPTES) for surface functionalization, adapted to the sulfide solid electrolyte LGPS (Li 10 GeP2S 12 ).

[0084] 1. Material preparation Copper foil: Rolled copper foil, 8μm thick, 99.9% pure; Micropore fabrication: Ultraviolet laser drilling was used to prepare blind hole structures with a diameter of 15μm, a depth of 8μm, a spacing of 25μm, and a porosity of approximately 28%.

[0085] Functionalizing reagent: (3-mercaptopropyl)triethoxysilane (MPTES), prepared as a 2% (v / v) MPTES@ethanol / water mixed solution (ethanol:water volume ratio = 95:5), pH adjusted to 4-5 with glacial acetic acid, and hydrolyzed and activated for 30 minutes for later use.

[0086] Sulfide solid electrolyte: LGPS (Li 10 GeP2S 12 Nanoparticles were prepared by high-energy ball milling and dispersed in anhydrous acetonitrile at a concentration of 10 mg / mL.

[0087] 2. Preparation process Step 1: Pretreatment of microporous copper foil is the same as in Example 1.

[0088] Step 2: Surface functionalization modification The pretreated microporous copper foil was immersed in a hydrolyzed and activated MPTES solution at 40°C for 2 hours. This allowed MPTES molecules to be anchored to the copper foil surface through the chemical adsorption of thiol groups (-SH). Simultaneously, the silanol groups (Si-OH) generated from the hydrolysis of silane groups (-Si(OCH2CH3)3) partially condensed to form a flexible siloxane network. After removal, the foil was rinsed with anhydrous ethanol to remove excess physically adsorbed molecules, and then vacuum dried at 80°C for 30 minutes to solidify the interface layer.

[0089] Step 3: In-situ bonding and shaping of the LGPS electrolyte layer The functionalized copper foil was immersed in a dispersion of LGPS nanoparticles and allowed to stand for 10 minutes before being removed. Vacuum-assisted filling was then performed, with the pressure evacuated to -0.1 MPa and maintained for 15 minutes to ensure the dispersion fully wetted and filled the micropores. Subsequently, a hot-pressing process was conducted under an argon atmosphere, with the pressure controlled at 150 MPa and the temperature at 80°C, and the temperature and pressure maintained for 30 minutes. During this process, the silanol groups (Si-OH) at the ends of the MPTES molecules undergo a dehydration condensation reaction with the metal hydroxyl groups (mainly P-OH and a small amount of Ge-OH) formed by trace oxidation on the surface of the LGPS particles, generating Si-OP and a small amount of Si-O-Ge covalent bonds.

[0090] Step 4: Battery Assembly and Performance Testing The button cells were assembled according to the method in Example 1, and the test results are shown in Table 6 below: Table 6 Example 6 This embodiment uses a rolled copper foil substrate and employs dopamine hydrochloride combined with a phosphorylation reagent to achieve surface functionalization, and is adapted to the sulfide solid electrolyte Li6PS5Cl.

[0091] 1. Material preparation Copper foil: Rolled copper foil, 8μm thick, 99.9% pure; Micropore fabrication: Ultraviolet laser drilling was used to prepare blind hole structures with a diameter of 15μm, a depth of 8μm, a spacing of 25μm, and a porosity of approximately 28%.

[0092] Functionalizing reagents: dopamine hydrochloride (PDA) + phosphorylation reagent (POCl3). PDA was prepared as 2 mg / mL dopamine Tris buffer (pH 8.5), and POCl3 was prepared as 10 mM POCl3@acetonitrile solution.

[0093] 2. Preparation process Step 1: Pretreatment of microporous copper foil is the same as in Example 1.

[0094] Step 2: Surface functionalization modification Preparation of functionalization reagents. The pretreated copper foil was immersed in 2 mg / mL dopamine Tris buffer (pH 8.5) for 6 h to form a polydopamine anchoring layer. After removal, it was rinsed with deionized water and dried under nitrogen. Then it was immersed in 10 mM POCl3@acetonitrile solution and reacted at 40 °C for 6 h to complete phosphorylation and introduce the -PO4 functional group. After removal, it was rinsed with acetonitrile and dried under nitrogen.

[0095] Step 3: In-situ bonding and characterization of Li6PS5Cl To prepare a dispersion of Li6PS5Cl nanoparticles, functionalized copper foil was immersed in the dispersion and then vacuum-assisted filling was performed, followed by cold pressing at 150 MPa. The bonding mechanism is that phosphate groups form PS-Li ionic bonds with Li2S on the sulfide surface.

[0096] Step 4: Battery Assembly and Performance Testing The button cells were assembled according to the method in Example 1, and the test results are shown in Table 7 below: Table 7 Example 7 In this embodiment, a rolled copper foil substrate is used, and 3-mercaptopropionic acid (MPA) is used as a bifunctional organic molecule to achieve surface functionalization, which is adapted to PEO-based polymer solid electrolyte.

[0097] 1. Material preparation Copper foil: Rolled copper foil, 8μm thick, 99.9% pure; Micropore fabrication: Ultraviolet laser drilling was used to prepare blind hole structures with a diameter of 15μm, a depth of 8μm, a spacing of 25μm, and a porosity of approximately 28%.

[0098] Functionalizing reagent: 3-mercaptopropionic acid (MPA, Sigma-Aldrich, 99% purity) was prepared into a 10 mM MPA@ethanol solution, and the pH was adjusted to 5.0 with dilute hydrochloric acid to obtain a mixed solution of functionalizing reagent.

[0099] Polymer solid electrolyte precursor: PEO-acrylate copolymer as matrix (number average molecular weight Mn=200000, acrylate unit molar fraction 15%) was dissolved in anhydrous acetonitrile, lithium bis(trifluoromethanesulfonylimide) (LiTFSI) was added as lithium salt (20 wt%), and photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173, mass fraction 0.5%) was added. The mixture was stirred until homogeneous to obtain a homogeneous precursor solution with a concentration of 30 wt%.

[0100] 2. Preparation process Step 1: Pretreatment of microporous copper foil is the same as in Example 1.

[0101] Step 2: Surface functionalization modification Pretreated microporous copper foil was immersed in a 0.01 mol / L ethanol solution of 3-mercaptopropionic acid at 40°C for 4 hours. This allowed 3-mercaptopropionic acid molecules to be anchored to the copper foil surface via chemisorption of their thiol groups (-SH), forming a self-assembled monolayer. After immersion, the foil was rinsed with anhydrous ethanol to remove excess physically adsorbed molecules and dried with nitrogen. The exposed carboxyl groups (-COOH) on the copper foil surface at this point serve as active sites for subsequent polymer interactions.

[0102] Step 3: In-situ polymerization and interfacial bonding of the polymer electrolyte layer The functionalized copper foil was placed flat on a coating stage, and a PEO-acrylate precursor solution was uniformly coated onto the copper foil surface using a doctor blade, with the coating thickness controlled at 50 μm. Vacuum-assisted filling was employed, with the pressure evacuated to -0.1 MPa and maintained for 10 minutes to ensure the precursor solution fully wetted and filled the micropores. Subsequently, ultraviolet light irradiation (wavelength 365 nm, light intensity 20 mW / cm², irradiation time 10 minutes) was performed under a nitrogen atmosphere to initiate the C=C double bond crosslinking polymerization of the acrylate units. During this process, the carboxyl group (-COOH) at the end of the MPA molecule forms hydrogen bonds with the ether oxygen (COC) in the PEO chain segment, and simultaneously interacts with the Li dissociated from the lithium salt. + Coordination occurs, forming ion-dipole interactions, thereby creating a multi-layered physically cross-linked interfacial network structure between the polymer electrolyte and the copper foil. After UV polymerization, the sample is dried in a vacuum drying oven at 60°C for 12 hours to remove residual solvent.

[0103] Step 4: Pre-storage lithium treatment: Lithium metal was filled into the micropores and electrolyte surface by hot pressing at 120℃ and 150MPa for 5 minutes.

[0104] The button cells were assembled according to the method in Example 1, and the test results are shown in Table 8 below: Table 8 Example 8 This embodiment uses thiol-functionalized microporous copper foil as the core substrate. By preparing a PEO-based polymer containing reactive acrylate end groups, in-situ bonding of thiol groups and carbon-carbon double bonds is achieved through ultraviolet light-initiated polymerization.

[0105] 1. Material preparation Copper foil: Rolled copper foil, 8μm thick, 99.9% pure; Micropore fabrication: Ultraviolet laser drilling was used to prepare blind hole structures with a diameter of 15μm, a depth of 8μm, a spacing of 25μm, and a porosity of approximately 28%.

[0106] Functionalizing reagent: (3-mercaptopropyl)triethoxysilane (MPTES), prepared by mixing MPTES, ethanol and water in a volume ratio of 8:87:5, and adjusting the pH to 4.5 with glacial acetic acid.

[0107] Polymer solid electrolyte precursor: The preparation method is the same as in Example 7.

[0108] 2. Preparation process Step 1: Pretreatment of microporous copper foil is the same as in Example 1.

[0109] Step 2: Surface functionalization modification Prepare functionalization reagents. Immerse pretreated copper foil in the reagents, sonicate for 10 min, soak at 40℃ for 8 h, wash with anhydrous ethanol and dry to complete thiol anchoring.

[0110] Step 3: Polymer coating and polymerization: A PEO-acrylate precursor containing 20% ​​LiTFSI (30wt% solids content, anhydrous acetonitrile as solvent) was slit-coated onto a functionalized copper foil (15μm thick). The coating was then subjected to 365nm UV light at 30mW / cm². 2 Expose under light intensity for 60 seconds to achieve in-situ bonding of thioether bonds, and then vacuum dry at 40℃ for 12 hours.

[0111] Step 4: Pre-storage lithium treatment: Lithium metal was filled into the micropores and electrolyte surface by hot pressing at 120℃ and 150MPa for 5 minutes.

[0112] Comparative Example 3 Comparative Example 3 was prepared by applying unfunctionalized copper foil with conventional PEO physical coating.

[0113] 1. Material preparation Copper foil: Rolled copper foil, 8μm thick, 99.9% pure; Micropore fabrication: Ultraviolet laser drilling was used to prepare blind hole structures with a diameter of 15μm, a depth of 8μm, a spacing of 25μm, and a porosity of approximately 28%.

[0114] Polymer system: PEO-based polymer with acrylate end groups (PEO-acrylate copolymer) + LiTFSI.

[0115] 2. Preparation process Step 1: Pretreatment of microporous copper foil is the same as in Example 1.

[0116] Step 2: Polymer coating and polymerization: A PEO-acrylate precursor containing 20% ​​LiTFSI (30wt% solids content, anhydrous acetonitrile as solvent) was slit-coated onto an unfunctionalized copper foil (15μm thick).

[0117] Step 3: Battery Assembly and Performance Testing The button cells of Example 8 and Comparative Example 3 were assembled according to the method of Example 1, and the test results are shown in Table 5 below: Table 9 This invention covers three typical solid-state electrolyte systems: oxides, sulfides, and polymers. Through various surface functionalization strategies and in-situ bonding processes, a stable chemical bonding interface is constructed between the microporous copper foil and the solid-state electrolyte, achieving integrated manufacturing. Test results show that compared with traditional physical bonding methods, this structure exhibits significant advantages in interfacial bonding strength, interfacial impedance, and cycle stability. It effectively reduces interfacial impedance and improves interfacial stability, thereby enhancing the overall electrochemical performance of solid-state batteries and demonstrating promising application prospects in the field of all-solid-state lithium batteries.

[0118] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A microporous copper foil current collector with interfacial chemical bonding, characterized in that, The current collector includes: The microporous copper foil substrate is a rolled copper foil or an electrolytic copper foil with a thickness of 4-12 μm. The substrate has a microporous structure with a pore size of 5-30 μm, a pore depth of 3-10 μm, and a porosity of 20%-60%. The microporous structure is a through-hole and / or a blind hole. A copper surface anchoring layer, wherein the copper surface anchoring layer is composed of bifunctional organic molecules; the bifunctional organic molecules include a first functional group and a second functional group; wherein the first functional group includes one or more of thiol groups -SH or -NH2, which are used to form coordination bonds or covalent bonds with the copper surface, so that the bifunctional organic molecules are anchored on the surface of the microporous copper foil substrate and the inner wall of the microporous structure; the second functional group includes one or more of -COOH, -PO4 or -Si(OR)3. The solid electrolyte interface reaction layer is composed of a chemical bond network formed by the in-situ reaction between the second functional group and the surface groups of the solid electrolyte or its precursor; the chemical bond network includes one or more of covalent bonds, coordinate bonds or ionic bonds; wherein the chemical bond network includes a metal element M, which is a metal element derived from the solid electrolyte, including one or more of Li, La, Zr, Ti or Al.

2. The interfacial chemically bonded microporous copper foil current collector according to claim 1, characterized in that, The solid electrolyte includes one or more of the following: oxide solid electrolyte, sulfide solid electrolyte, or polymer solid electrolyte; The precursor of the oxide solid electrolyte undergoes an in-situ reaction with the second functional group of the bifunctional organic molecule, silyl-Si(OR)3. The silyl group hydrolyzes under water or humidity conditions to generate silanol group Si-OH, which undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a Si-OM covalent bond. The precursor of the oxide solid electrolyte undergoes an in-situ reaction with the second functional group phosphate group -PO4 of the bifunctional organic molecule, and the phosphate group undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a POM covalent bond; The precursor of the oxide solid electrolyte undergoes an in-situ reaction with the second functional group -COOH of the difunctional organic molecule. The carboxyl group interacts with the metal atom M on the surface of the oxide solid electrolyte through the lone pair electrons on its oxygen atom to form a coordinate bond. The sulfide solid electrolyte undergoes an in-situ reaction with the second functional group phosphate group -PO4 of the bifunctional organic molecule. The phosphate group reacts with Li2S or sulfur-containing species on the surface of the metal ion polymer solid electrolyte to form an ionic bond network through PS-Li chemical bonding. The sulfide solid electrolyte undergoes an in-situ reaction with the second functional group (carboxyl group -COOH) of the bifunctional organic molecule. The carboxyl group then reacts with lithium sulfide (Li₂S) on the surface of the sulfide solid electrolyte in an acid-base reaction to form -COO. - Li + Interface ionic bonds; The sulfide solid electrolyte undergoes an in-situ reaction with the second functional group silyl group -Si(OR)3 of the difunctional organic molecule. The silyl group hydrolyzes under water or humidity conditions to generate silanol group Si-OH, which then undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH formed on the oxide layer of the sulfide solid electrolyte surface to form a Si-OM covalent bond. The precursor of the polymer solid electrolyte undergoes an in-situ reaction with the second functional group (carboxyl group -COOH) of the bifunctional organic molecule. Under the action of an initiator or crosslinking agent, the carboxyl group undergoes a ring-opening or condensation reaction with a specific functional group on the polymer electrolyte chain segment to form a covalent crosslinked network structure. The specific functional group includes one or more of epoxy, hydroxyl, or amino groups.

3. The interfacial chemically bonded microporous copper foil current collector according to claim 2, characterized in that, The polymer solid electrolyte contains C=C double bond end groups, and the thiol group -SH in the bifunctional organic molecule also serves as the second functional group; The thiol-SH group undergoes radical addition with the C=C double bond end group in the precursor of the polymer solid electrolyte via a thiol-alkene click reaction, forming a covalent bond structure of thioether bond -SC- at the interface.

4. The interfacial chemically bonded microporous copper foil current collector according to claim 2, characterized in that, The bifunctional organic molecule includes one or more of the following: 3-mercaptopropionic acid, (3-mercaptopropyl)trialkoxysilane, or dopamine or its derivatives grafted with a phosphorylating agent to form a bifunctional organic molecule. The oxide solid electrolyte includes lithium lanthanum zirconium oxide (LLZO) or lithium aluminum titanium phosphate (LATP). The sulfide solid electrolyte includes lithium germanium phosphide sulfide LGPS or Li6PS5Cl. The polymer solid electrolyte comprises a polymer matrix and a lithium salt, wherein the polymer matrix comprises a polyethylene oxide (PEO)-acrylate polymer, wherein acrylate groups are attached to one or both ends of the PEO chain, and the lithium salt comprises LiTFSI.

5. A method for preparing the interfacial chemically bonded microporous copper foil current collector according to any one of claims 1-4, characterized in that, The preparation method includes: S1. Microporous copper foil pretreatment: The copper foil is laser-drilled or chemically etched to form a microporous array structure. Then, it is sequentially cleaned with organic solvent, acid pickled and deionized water to remove oil and natural oxide layer on the surface. After drying, the pretreated microporous copper foil is obtained. S2. Surface functionalization modification treatment: The pretreated microporous copper foil is immersed in a solution containing bifunctional organic molecules, so that the first functional group of the bifunctional organic molecules forms a coordination bond or covalent bond with the copper surface, thereby forming a copper surface anchoring layer on the surface of the microporous copper foil and the inner wall of the microporous structure. S3. In-situ bonding treatment of solid electrolyte: Based on the system of the solid electrolyte material used, select the corresponding bonding route, so that the second functional group of the difunctional organic molecule reacts in situ with the surface groups of the solid electrolyte or its precursor to form a solid electrolyte interface reaction layer, and the solid electrolyte is bonded to the surface of the microporous copper foil and the inner wall of the microporous structure through the copper surface anchoring layer to obtain the interfacial chemically bonded microporous copper foil current collector.

6. The preparation method according to claim 5, characterized in that, The step of immersing the pretreated microporous copper foil in a solution containing bifunctional organic molecules specifically includes: The pretreated microporous copper foil is immersed in a solution containing bifunctional organic molecules. By using negative pressure-assisted permeation or ultrasonic-assisted wetting, the solution containing bifunctional organic molecules enters the microporous structure and wets the bottom and walls of the microporous structure.

7. The preparation method according to claim 5, characterized in that, The selection of the appropriate bonding route based on the system using the solid electrolyte material includes: When using an oxide solid electrolyte, the bonding route is selected with (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule; or, the bonding route is selected with 3-mercaptopropionic acid as the bifunctional organic molecule; or, the bonding route is selected with dopamine or its derivative grafted with a phosphorylating agent to form a bifunctional organic molecule. When using a sulfide solid electrolyte, the bonding route is selected with the difunctional organic molecule (3-mercaptopropyl)trialkoxysilane; or, the bonding route is selected with the difunctional organic molecule 3-mercaptopropionic acid; or, the bonding route is selected with the difunctional organic molecule formed by grafting dopamine or its derivatives with a phosphorylation reagent. When using a polymer solid electrolyte, the bonding route with the difunctional organic molecule (3-mercaptopropyl)trialkoxysilane is selected; or, the bonding route with the difunctional organic molecule 3-mercaptopropionic acid is selected.

8. The preparation method according to claim 5, characterized in that, When using an oxide solid electrolyte, the bonding route using (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule specifically includes: immersing a microporous copper foil in a mixed solution of ethanol and / or water containing (3-mercaptopropyl)triethoxysilane, adjusting the pH of the solution to 4-5 to obtain a surface-functionalized copper foil; preparing a precursor sol for the oxide solid electrolyte, immersing the surface-functionalized copper foil in the precursor sol, soaking at 25-60℃ for 1-24 hours, followed by dip-coating, then evaporating at 150℃ to remove the solvent, and then holding at 300-600℃ for 1-4 hours to allow the silanol group Si-OH to undergo a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a Si-OM covalent bond; preferably, the precursor sol also includes a metal alkoxide. When using an oxide solid electrolyte, the bonding route using 3-mercaptopropionic acid as the bifunctional organic molecule specifically includes: immersing a microporous copper foil in an ethanol solution containing 3-mercaptopropionic acid, wherein the concentration of 3-mercaptopropionic acid in the solution is 0.001-0.05 mol / L, to obtain a copper foil with surface functionalization modification; preparing a precursor sol for the oxide solid electrolyte, immersing the surface functionalized copper foil in the precursor sol, soaking it at 25-60℃ for 1-24 hours, then performing a dip-coating process, subsequently evaporating to remove the solvent at 150℃, and then heat-treating at 300-600℃. During this process, the carboxyl group -COOH of the bifunctional organic molecule coordinates with the metal atom M on the surface of the oxide solid electrolyte through the lone pair electrons on its oxygen atom, thereby forming a -COO-M coordination bond at the interface, achieving chemical bonding between the oxide solid electrolyte and the microporous copper foil; When using an oxide solid electrolyte, the bonding route for selecting a bifunctional organic molecule as a grafted dopamine or its derivative with a phosphorylation reagent specifically includes: dissolving dopamine hydrochloride in a Tris buffer solution and adjusting the pH to 8-9; immersing the microporous copper foil in the solution for self-polymerization deposition to form a polydopamine functional layer on the copper surface; subsequently immersing the copper foil in a solution containing a phosphorylation reagent for a grafting reaction, allowing the active sites on the polydopamine molecule to bind with the phosphorylation reagent, forming a bifunctional organic molecule layer containing phosphate group -PO4 on the copper surface; then immersing the copper foil in the oxide solid electrolyte precursor sol and performing dip-coating and heat treatment, causing the phosphate group -PO4 to undergo a dehydration condensation reaction with the metal hydroxyl group M-OH on the surface of the oxide solid electrolyte to form a POM covalent bond; When using a sulfide solid electrolyte, the bonding route using the bifunctional organic molecule 3-mercaptopropionic acid specifically includes: immersing a microporous copper foil in an ethanol solution containing 3-mercaptopropionic acid, wherein the concentration of 3-mercaptopropionic acid in the solution is 0.001-0.05 mol / L, to obtain a surface-functionalized copper foil; preparing a nanoparticle dispersion of the sulfide solid electrolyte Li6PS5Cl or LGPS; immersing the surface-functionalized copper foil in the dispersion; and using vacuum-assisted filling to allow the sulfide solid electrolyte particles to enter the microporous structure; subsequently, hot-pressing treatment is performed at 100-200 MPa pressure and 25-150℃. During this process, the carboxyl group -COOH of the bifunctional organic molecule reacts with the Li2S on the surface of the sulfide solid electrolyte to generate -COO. - Li + Interfacial ionic bonds are formed between the sulfide solid electrolyte and the microporous copper foil, thereby creating an interfacial ionic bond network. When using a sulfide solid electrolyte, the bonding route using (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule specifically includes: immersing a microporous copper foil in a mixed solution of ethanol and / or water containing (3-mercaptopropyl)triethoxysilane, adjusting the pH of the solution to 4-5 to obtain a surface-functionalized copper foil; preparing a nanoparticle dispersion of the sulfide solid electrolyte Li6PS5Cl or LGPS; immersing the surface-functionalized microporous copper foil in the dispersion, and using negative pressure-assisted permeation or vacuum-assisted filling to allow the sulfide solid electrolyte particles to enter the microporous electrolyte. The porous structure is filled inside and covers the surface of the microporous copper foil. Then, hot pressing is performed under a pressure of 100-200 MPa and a temperature of 25-150°C to compact the sulfide solid electrolyte particles in the microporous structure and form a dense contact. During this process, the silyl group of the bifunctional organic molecule, silyl-Si(OR)3, hydrolyzes under water or humidity conditions to generate silanol group Si-OH, which undergoes a dehydration condensation reaction with the metal hydroxyl group M-OH formed on the oxide layer of the sulfide solid electrolyte surface to form a Si-OM covalent bond, thereby forming a stable interfacial chemical bond structure between the microporous copper foil and the sulfide solid electrolyte. When using a sulfide solid electrolyte, the specific bonding route for selecting a difunctional organic molecule as the grafted dopamine or its derivative with a phosphorylation reagent includes: first, dissolving dopamine hydrochloride in a Tris buffer solution and adjusting the pH to 8-9; immersing the microporous copper foil in this solution for self-polymerization deposition to form a polydopamine functional layer on the copper surface; subsequently, immersing the copper foil in a solution containing a phosphorylation reagent for a grafting reaction, allowing the active sites on the polydopamine molecules to bind with the phosphorylation reagent, forming a layer on the copper surface. A bifunctional organic molecular layer containing phosphate group -PO4 is formed. Then, the copper foil is immersed in a nanoparticle dispersion of sulfide solid electrolyte Li6PS5Cl or LGPS, and the sulfide solid electrolyte particles are introduced into the microporous structure by vacuum-assisted filling. Subsequently, hot pressing is performed under a pressure of 100-200MPa and a temperature of 25-150℃. During this process, the phosphate group -PO4 reacts with the sulfur-containing species on the surface of the sulfide solid electrolyte to form PS-Li chemical bonds, thereby constructing a stable interfacial ionic bond network. When using a polymer solid electrolyte, the bonding route using 3-mercaptopropionic acid as the bifunctional organic molecule specifically includes: immersing a microporous copper foil in an ethanol solution containing 3-mercaptopropionic acid, wherein the concentration of 3-mercaptopropionic acid in the solution is 0.001-0.05 mol / L, to obtain a surface-functionalized copper foil; preparing a PEO-based polymer solid electrolyte precursor solution containing reactive end groups, and coating it onto the surface and interior of the microporous structure of the surface-functionalized copper foil, wherein the PEO-based polymer is a PEO-acrylate polymer containing lithium salt LiTFSI; subsequently, an in-situ polymerization reaction is carried out under ultraviolet light or thermal initiation conditions, wherein the carboxyl-COOH group can undergo hydrogen bonding or coordination with the hydroxyl or ether oxygen in the polymer chain segment, thereby forming a chemical bond structure at the interface; When using a polymer solid electrolyte, the bonding route using (3-mercaptopropyl)trialkoxysilane as the bifunctional organic molecule specifically includes: the thiol-SH group in the bifunctional organic molecule simultaneously functions as the second functional group; immersing a microporous copper foil in a mixed solution of ethanol and / or water containing (3-mercaptopropyl)triethoxysilane, adjusting the pH of the solution to 4-5, to obtain a copper foil with surface functionalization modification; preparing a PEO-based polymer solid electrolyte precursor solution containing reactive end groups, and coating it onto the surface and interior of the microporous structure of the surface-functionalized microporous copper foil, wherein the PEO-based polymer is a PEO-acrylate polymer containing lithium salt LiTFSI; subsequently, an in-situ polymerization reaction is carried out under ultraviolet light or thermal initiation conditions, causing the thiol-SH group in the bifunctional organic molecule to undergo a free radical addition reaction with the C=C double bond of the polymer solid electrolyte chain segment end group, forming a -SC-thioether covalent bond at the interface, thereby constructing a covalent cross-linked interface structure between the polymer solid electrolyte and the microporous copper foil.

9. A negative electrode, characterized in that, The negative electrode comprises the interfacial chemically bonded microporous copper foil current collector as described in any one of claims 1-4.

10. A solid-state lithium battery, characterized in that, The solid-state lithium battery includes the negative electrode described in claim 9.

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