Functional current collector with optimized base layer, preparation method of functional current collector, pole piece and battery

Abstract

The invention discloses a functional current collector for optimizing a bottom layer, a preparation method of the functional current collector, a pole piece and a battery. The functional current collector comprises a high-molecular base membrane layer, a recrystallization bottom layer on the outer side of the high-molecular base membrane layer and a metal layer on the outer side of the recrystallization bottom layer, and the recrystallization base layer is composed of a recrystallization product of a metal oxide. Lattice defects are repaired through recrystallization, a compact and continuous crystal net is formed, the metal deposition behavior can be optimized through the recrystallization base layer, the compact crystal structure of the recrystallization base layer forms a physical barrier layer, electrolyte permeation can be effectively inhibited, corrosion of corrosive ions to a base film can be effectively blocked, an electron transmission path is optimized by constructing the recrystallization base layer, and the service life of the base film is prolonged. And local current concentration is avoided. The comprehensive performance of the current collector is improved through dual effects of interface stability and process adaptability.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a functional current collector with an optimized base layer, a preparation method thereof, a pole piece and a battery. Background Art

[0002] As the core carrier of electron transport in the positive and negative electrode materials of lithium-ion batteries, current collectors are a crucial component of the battery structure. Composite current collectors, employing a "metal-polymer-metal" sandwich structure, demonstrate significant potential for improving battery safety and energy density due to their unique structural advantages. Current composite aluminum current collector preparation processes primarily utilize polymer film substrates, depositing nanoscale metal oxide and metal coatings through techniques such as vacuum evaporation or magnetron sputtering.

[0003] The performance advantages of the composite current collector material itself have been experimentally verified, but due to the limitations of equipment precision and process maturity, there are still several technical bottlenecks. Specifically, the metal oxide layer formed by vacuum evaporation and magnetron sputtering processes often exhibits problems such as insufficient crystallinity and microstructural defects, which complicates the surface morphology of the coating. This structural characteristic weakens the interfacial bonding strength between the metal layer and the polymer base film, and at the same time leads to a decrease in the adhesion between different coatings. In the battery working environment, such bonding defects will significantly reduce the material's resistance to electrolyte corrosion and cause interfacial peeling between the metal coating and the base film. Metal delamination not only directly destroys the conductive network of the current collector, causing a significant attenuation of the conductivity of the electrode material, but also aggravates the increase in the internal resistance of the battery, ultimately posing a safety hazard. Summary of the Invention

[0004] The purpose of the present invention is to provide a functional current collector with an optimized bottom layer, a preparation method thereof, a pole piece and a battery, and to solve the above-mentioned problems by improving the performance of the functional current collector.

[0005] To achieve the above object, the technical solution provided by the present invention is:

[0006] The first aspect of the present application provides a functional current collector with an optimized primer layer, comprising a polymer base film layer, a recrystallized primer layer outside the polymer base film layer, and a metal layer outside the recrystallized primer layer;

[0007] The composition of the recrystallization primer layer is the recrystallization product of metal oxide.

[0008] The second aspect of the present application provides a method for preparing a functional current collector with an optimized bottom layer, comprising the following steps:

[0009] S1: preparing a metal oxide layer on the surface of the polymer base film layer;

[0010] S2: Recrystallizing the metal oxide layer using an oxidant to form a recrystallized base layer on the surface of the polymer base film layer;

[0011] S3: preparing a metal layer on the surface of the recrystallized base layer.

[0012] To optimize the above technical solutions, specific measures taken also include:

[0013] Furthermore, the metal oxide layer is prepared by physical vapor deposition, chemical vapor deposition or in-situ forming.

[0014] Furthermore, the thickness of the metal oxide layer is 2 to 20 nm.

[0015] Furthermore, the oxidant is selected from at least one of sodium periodate, potassium periodate, potassium permanganate, potassium dichromate, potassium chlorate, hydrogen peroxide, trivalent cobalt salt, and oxoacid salt.

[0016] Preferably, the reaction of using an oxidant for recrystallization is specifically:

[0017] The metal oxide layer is oxidized by using an oxidant solution, and then heated and baked at 80 to 120° C. to form a recrystallized base layer.

[0018] Furthermore, the oxidizing of the metal oxide layer using the oxidant solution is carried out by any one of coating, spraying, electrophoresis or flow coating.

[0019] Furthermore, the metal oxide primer layer is selected from any one of nickel oxide, aluminum oxide, and silicon oxide.

[0020] The third aspect of the present application provides a pole piece comprising the above-mentioned functional current collector.

[0021] A fourth aspect of the present application provides a battery comprising the above-mentioned electrode.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention forms a recrystallization base layer between the polymer base film layer and the metal layer by performing a recrystallization treatment on the metal oxide layer of the functional current collector. The recrystallization base layer is used to improve the bonding strength between the metal layer and the polymer base film layer and between the metal layers, thereby reducing problems such as discontinuity and localized shedding of the metal layer caused by poor bonding between the metal layer and the polymer base film layer, thereby improving the electrolyte corrosion resistance of the functional current collector.

[0024] The present invention repairs lattice defects through recrystallization to form a dense and continuous crystal network, thereby achieving chemical bonding strengthening at the organic-inorganic interface; the recrystallization base layer of the present invention can optimize metal deposition behavior, and its dense crystal structure forms a physical barrier layer, which can effectively inhibit electrolyte penetration and block the erosion of corrosive ions on the base film; the recrystallization base layer of the present invention also significantly optimizes the electron transmission path by eliminating the amorphous interface phase, thereby avoiding local current concentration.

[0025] Thus, the structural-functional synergy of the present invention achieves a systematic improvement in the mechanical strength, interface stability and corrosion resistance of the current collector. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : Schematic diagram of the structure of the functional current collector with optimized bottom layer of the present invention.

[0027] In the figure: 1-polymer base film layer, 2-recrystallization base layer, 3-metal layer. DETAILED DESCRIPTION

[0028] The above contents of the present invention are further described in detail below in the form of specific implementation methods, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments. All technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0029] The experimental methods used in the following examples are conventional methods unless otherwise specified, and the reagents, methods and equipment used are conventional reagents, methods and equipment in the art unless otherwise specified.

[0030] For the sake of simplicity, this document only specifically discloses some numerical values ​​and optional ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range. Similarly, any upper limit can be combined with any other upper limit to form an unspecified range; the optional items in the optional range can also be combined arbitrarily.

[0031] Unless otherwise specified, the terms used in this application have the commonly known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art.

[0032] The present invention provides a functional current collector with an optimized bottom layer, such as Figure 1 As shown, it includes a polymer base film layer 1, a recrystallization base layer 2 outside the polymer base film layer, and a metal layer 3 outside the recrystallization base layer;

[0033] The recrystallized base layer 2 is composed of a recrystallized product of a metal oxide.

[0034] The present invention also provides a method for preparing a functional current collector with an optimized bottom layer, comprising the following steps:

[0035] S1: preparing a metal oxide layer on the surface of the polymer base film layer;

[0036] S2: Recrystallizing the metal oxide layer using an oxidant to form a recrystallized base layer on the surface of the polymer base film layer;

[0037] S3: preparing a metal layer on the surface of the recrystallized base layer.

[0038] This invention enhances the material's electrical conductivity through recrystallization using an oxidizing agent. This process also forms stable chemical bonds with oxygen-containing functional groups in the polymer base film, significantly increasing the interfacial bonding strength between the substrate and the base coat. Furthermore, the optimized base coat structure strengthens the anchoring of subsequent metal ions at the interface, increasing the inter-coating bonding strength in a stepwise manner, ultimately achieving a systematic enhancement of overall interface stability.

[0039] This technology effectively addresses defects such as missed plating and pinholes in metal layer preparation processes, such as vacuum evaporation, while significantly suppressing metal layer shedding, cracking, and discontinuity in the functional current collector when exposed to electrolytes. By achieving these dual improvements in interface stability and process adaptability, this solution enables the current collector's comprehensive performance to meet the stringent requirements for high-reliability materials in the new energy sector.

[0040] The present invention constructs a functional recrystallization transition layer between the polymer base film and the metal layer through an oxidant-induced recrystallization process, which can achieve multi-scale interface regulation and structural optimization:

[0041] During the recrystallization process, the oxidant first acts as a lattice activator to intervene in the phase transition of the metal oxide layer. By releasing reactive oxygen species, it promotes the dissociation and recombination of aluminum-oxygen bonds, driving the transformation of the amorphous or low-crystallinity oxide into a highly ordered crystalline structure. This reconstruction process effectively repairs lattice defects, forming a dense and continuous crystalline network whose grain orientation forms a topological match with the surface morphology of the polymer substrate, enhancing the interfacial anchoring ability through a mechanical interlocking effect. Simultaneously, the reconstructed crystal surface exposes a large number of unsaturated oxygen atoms and metal active sites, which chemically adsorb with the polar functional groups of the polymer substrate and form a stable hydrogen bond network through an oxidant-induced hydroxylation reaction, achieving chemical bonding strengthening at the organic-inorganic interface.

[0042] The structural characteristics of the recrystallized base layer further optimize the metal deposition behavior. Its regularly arranged crystal planes provide an epitaxial growth template for metal atoms, significantly reducing the lattice mismatch stress of the heterogeneous interface. The metal atoms form strong covalent bonds with the oxygen vacancies in the oxide lattice, fundamentally solving the problem of insufficient bonding caused by physical adhesion in traditional coatings. This strengthened interface can effectively inhibit the penetration of electrolytes. Its dense crystal structure forms a physical barrier layer, blocking the corrosion of corrosive ions on the base film. At the same time, the high crystallinity surface reduces the density of electrochemically active sites, inhibiting the oxidation and dissolution of the metal layer through the passivation effect. Under dynamic working conditions, the gradient design of the expansion coefficient difference gives the transition layer a stress buffering function, which can absorb the volume deformation energy during the electrode cycle and prevent the expansion of metal layer cracks caused by interface fatigue.

[0043] From the perspective of electrochemical performance, the recrystallized layer also significantly optimizes the electron transmission path by eliminating the amorphous interface phase. Its three-dimensional connected crystal structure reduces the Schottky barrier at the contact interface and promotes carrier tunneling conduction; the anisotropic conductive properties guide the metal layer to form a uniform deposition morphology, avoiding dendrite growth caused by local current concentration.

[0044] This structural-functional synergy ultimately achieves a systematic improvement in the mechanical strength, interface stability, and corrosion resistance of the current collector, providing a solution for the long-term cycle reliability of high-energy-density batteries.

[0045] In some preferred embodiments, the metal oxide layer is prepared by physical vapor deposition or chemical vapor deposition.

[0046] Specifically, the physical vapor deposition method is preferably vacuum evaporation or magnetron sputtering; the chemical vapor deposition method is preferably atmospheric pressure chemical vapor deposition or plasma enhanced chemical vapor deposition; the present invention can also adopt other optional methods, such as an in-situ forming method of forming a metal oxide passivation layer in situ on the surface of the metal layer.

[0047] The metal layer of the present invention can be prepared by commonly used methods such as vacuum evaporation and magnetron sputtering.

[0048] The polymer base film layer in the present invention can be selected from at least one of PET (polyethylene terephthalate), PE (polyethylene), PP (polypropylene), PEN (polyethylene naphthalate), PPTA (para-aromatic polyamide), PI (polyimide), PC (polycarbonate), PEEK (polyetheretherketone), POM (polyoxymethylene), PPS (polyphenylene sulfide), PPO (polyphenylene oxide), PVC (polyvinyl chloride), PA (polyamide) or PTFE (polytetrafluoroethylene), preferably PET (polyethylene terephthalate).

[0049] In some embodiments, the thickness of the metal oxide layer is 2 to 20 nm, preferably 3 to 15 nm.

[0050] The thickness of the polymer base film layer and the metal layer can be defined by the thickness of a conventional functional current collector, such as 2 to 10 μm for the polymer base film layer and 1 to 8 μm for the metal layer.

[0051] In some embodiments, the oxidizing agent is selected from, but not limited to, at least one of sodium periodate, potassium periodate, potassium permanganate, potassium dichromate, potassium chlorate, hydrogen peroxide, trivalent cobalt salts, and oxoacid salts.

[0052] In some embodiments, the reaction of using an oxidant for recrystallization is specifically:

[0053] The metal oxide layer is oxidized by using an oxidant solution, and then heated and baked at 80 to 120° C. to form a recrystallized base layer.

[0054] The metal oxide layer is oxidized using an oxidant solution by any one of coating, spraying, electrophoresis or flow coating.

[0055] The oxidant solution of the present invention adopts a high-concentration solution, and those skilled in the art can prepare and select it according to the strength and solubility of each oxidant.

[0056] In some embodiments, the metal oxide primer layer is selected from any one of nickel oxide, aluminum oxide, and silicon oxide.

[0057] The functional current collector in the present invention is preferably an aluminum functional current collector.

[0058] The present invention also provides a pole piece comprising the above-mentioned functional current collector.

[0059] The present invention also provides a battery comprising the above-mentioned electrode piece.

[0060] The technical solution of the present invention is further described in detail below with reference to specific embodiments:

[0061] Example 1

[0062] A high-performance aluminum functional current collector is prepared, and the specific steps are as follows:

[0063] (1) A 7 nm thick nickel oxide was prepared on a 6 μm thick PET base film by magnetron sputtering to obtain a first intermediate material; the magnetron sputtering parameters were: argon gas flow rate: 800 sccm, power: 15 kW;

[0064] (2) The first intermediate material is treated by solution coating with a sodium periodate solution having a concentration of 2.0 mol / L, with a winding speed of 200 m / min and a solution flow rate of 1 L / min; the film roll after coating is then heated and baked in a 100°C heating and baking device to obtain a second intermediate material.

[0065] (3) A 2 μm thick metal aluminum layer is prepared on the surface of the second intermediate material prepared in step (2) by vacuum evaporation to obtain an aluminum functional current collector, wherein the wire feeding rate is 350 mm / min and the winding speed is 13 m / min.

[0066] Example 2

[0067] The solution of this embodiment is basically the same as that of embodiment 1, except that in step (1), a magnetron sputtering method is used to prepare 7 nm thick aluminum oxide.

[0068] Example 3

[0069] The solution of this embodiment is basically the same as that of Example 1, except that in step (1), a vacuum evaporation method is used to prepare 7 nm thick aluminum oxide.

[0070] Example 4

[0071] The scheme of this embodiment is basically the same as that of Example 1, except that: step (2) uses 0.015 mol / L potassium periodate solution.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that the preparation of the aluminum functional current collector is not subjected to the bottom layer recrystallization treatment, that is, step (2) is not included, and the rest is the same as Example 1.

[0074] Comparative Example 2

[0075] The difference between this comparative example and Example 3 is that the preparation of the aluminum functional current collector is not subjected to the bottom layer recrystallization treatment, that is, step (2) is not included, and the rest is the same as Example 3.

[0076] The present application carried out multiple tests according to the conditions of the above embodiments and comparative examples, and then carried out experimental measurements, and took the average of the measurement results under the conditions of the embodiments and comparative examples. The results are shown in Table 1.

[0077] Test method:

[0078] 1. Electrolyte immersion test: Cut 6*8cm samples and seal them with aluminum-plastic film. In a glove box, inject 10ml of iron-lithium / ternary electrolyte into each bag of samples. Then use a sealing machine to seal the samples and place them in the glove box for 3 days. After 3 days, take out the samples, soak them in ethanol in a fume hood to clean off the surface electrolyte, and then perform a coating peel strength test on the samples.

[0079] 2. The peeling strength of the coating is measured by an electronic peeling strength tester (model BLD-200H): Cut a 120×50mm sample, stick the sample on a steel plate with 3M double-sided tape, roll it, and then stick 3M transparent tape on the sample. After rolling again, place the sample on the fixture of the electronic peeling strength tester to test the sample bonding strength value.

[0080] 3. The number of pinholes is measured by a flaw detector: Cut a 1×1m sample and place it on the detection surface of the flaw detector. Ensure that the sample is opaque around it, turn off the indoor lights, observe from a height of about 0.5 meters, and count the visible pinholes on the sample.

[0081] Table 1 Measurement results of various embodiments and comparative examples

[0082]

[0083] By comparing Examples 1 to 4, it can be seen that the base layers prepared by different process methods can be effectively optimized by oxidant recrystallization, and comparable effects can be achieved by using different oxidants. This solution can also be achieved for base layers made of either nickel oxide or aluminum oxide.

[0084] By comparing Example 1 and Comparative Examples 1 and 2, it can be seen that compared with the ordinary oxide base layer in the prior art that is not oxidized and recrystallized, the solution of the present application can significantly and evenly improve the plating peeling force and the plating peeling force after electrolyte immersion, and greatly reduce the number of pinholes, almost achieving no pinholes, thereby significantly improving the overall performance of the current collector.

[0085] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modification, equivalent replacement and improvement made by any technician familiar with the profession to the above embodiment without departing from the scope of the technical solution of the present invention and based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A functional current collector with an optimized bottom layer, characterized in that: It includes a polymer base film layer, a recrystallization primer layer outside the polymer base film layer, and a metal layer outside the recrystallization primer layer; The composition of the recrystallization primer layer is the recrystallization product of metal oxide.

2. A method for preparing a functional current collector with an optimized bottom layer, characterized in that: The following steps are involved: S1: preparing a metal oxide layer on the surface of the polymer base film layer; S2: Recrystallizing the metal oxide layer using an oxidant to form a recrystallized base layer on the surface of the polymer base film layer; S3: preparing a metal layer on the surface of the recrystallized base layer.

3. The method for preparing a functional current collector with an optimized bottom layer according to claim 2, wherein: The metal oxide layer is prepared by physical vapor deposition, chemical vapor deposition or in-situ forming.

4. The method for preparing a functional current collector with an optimized bottom layer according to claim 2, wherein: The thickness of the metal oxide layer is 2 to 20 nm.

5. The method for preparing a functional current collector with an optimized bottom layer according to claim 2, wherein: The oxidant is selected from at least one of sodium periodate, potassium periodate, potassium permanganate, potassium dichromate, potassium chlorate, hydrogen peroxide, trivalent cobalt salt, and oxoacid salt.

6. The method for preparing a functional current collector with an optimized bottom layer according to claim 2, wherein: The reaction of using an oxidant for recrystallization treatment is specifically: The metal oxide layer is oxidized by using an oxidant solution, and then heated and baked at 80 to 120° C. to form a recrystallized base layer.

7. The method for preparing a functional current collector with an optimized bottom layer according to claim 6, wherein: The metal oxide layer is oxidized by using the oxidant solution by any one of coating, spraying, electrophoresis or flow coating.

8. The method for preparing a functional current collector with an optimized bottom layer according to claim 2, wherein: The metal oxide base layer is selected from any one of nickel oxide, aluminum oxide and silicon oxide.

9. A pole piece, characterized in that: A functional current collector comprising the optimized bottom layer prepared by the method according to claim 1 or any one of claims 2 to 8.

10. A battery, characterized in that: Comprising the pole piece according to claim 9.

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