Functional current collector with double-barrier lithium dendrite function, preparation method, electrode plate and battery

Abstract

The invention discloses a functional current collector with a double-barrier lithium dendrite function, a preparation method of the functional current collector, an electrode plate and a battery, and belongs to the technical field of batteries. The surface of the substrate current collector is provided with a grid structure constructed by insulating separating walls, and the separating walls form a plurality of independent units in a surrounding manner; and a temperature-sensitive high polymer material is integrated in the independent unit. The method has the advantages of remarkably improving the safety of the battery, enhancing the stability of the battery and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and relates to a functional current collector, in particular to a functional current collector with a dual lithium dendrite blocking function and a preparation method, an electrode pole piece and a battery. BACKGROUND

[0002] With the wide application of lithium batteries in electric vehicles, energy storage and other fields, their safety and stability have become key problems to be solved. The growth of lithium dendrites is one of the important factors affecting the performance and safety of lithium batteries. During the charging and discharging process of lithium batteries, lithium metal is deposited unevenly on the surface of the negative electrode, which easily forms lithium dendrites. Lithium dendrites grow continuously and may pierce the separator, causing short circuit between the positive and negative electrodes of the battery, leading to serious safety accidents such as overheating, fire and even explosion of the battery.

[0003] At present, although various solutions have been proposed to address the problem of lithium dendrites, such as optimizing the electrolyte formula and improving the electrode material, these methods still have certain limitations and cannot completely and effectively inhibit the growth and expansion of lithium dendrites. Therefore, it is of great significance to develop a new and efficient lithium dendrite blocking technology to improve the performance and safety of lithium batteries. SUMMARY

[0004] The application provides a functional current collector with a dual lithium dendrite blocking function and a preparation method, an electrode pole piece and a battery to overcome the defects of the prior art.

[0005] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0006] In a first aspect, the application provides a functional current collector with a dual lithium dendrite blocking function, comprising a base current collector; the surface of the base current collector has a grid structure constructed by insulating isolation walls, and the isolation walls enclose a plurality of independent units; a temperature-sensitive polymer material is integrated in the independent units.

[0007] Further, the material of the isolation wall is one of nitrides, metal oxides, silicon-based ceramics and carbon-based ceramics; preferably, the nitride is one of boron nitride and aluminum nitride; preferably, the metal oxide is one of aluminum oxide and zirconium oxide; preferably, the silicon-based ceramic is one of silicon nitride and silicon oxide; and preferably, the carbon-based ceramic is silicon carbide.

[0008] Further, the temperature-sensitive polymer material is one of cross-linked poly(N-isopropylacrylamide) (cross-linked PNIPAM), PNIPAM-co-AAc and other cross-linked poly(N-isopropylacrylamide) copolymer, chitosan-based temperature-sensitive hydrogel, polyacrylamide (PAAm), polyacrylic acid (PAA), polyethylene glycol-polypropylene glycol block copolymer, poly N-vinyl caprolactam (PNVCL), temperature-sensitive polyurethane (TPU), poly(N,N-diethylacrylamide) (PDEA), polyvinyl alcohol (PVA)-based composite, flame retardant wrapping material, conductive-temperature-sensitive composite polymer material such as PTC material, polyethylene oxide-polypropylene oxide block copolymer (PEO-PPO), THFAA copolymer, and thermochromic liquid crystal polymer.

[0009] Further, the grid structure is composed of hexagonal isolation walls, in a honeycomb shape.

[0010] Further, the side length of the independent unit is 20-50 μm, the width of the isolation wall is 0.5-1 μm, and the height of the isolation wall is 1-3 μm.

[0011] Further, the isolation wall is prepared by photolithography-etching method, 3D printing, magnetron sputtering, vacuum evaporation, atomic layer deposition (ALD), or electrochemical method.

[0012] Further, the base current collector comprises a flexible polymer base film, a metal oxide layer arranged on both sides of the flexible polymer base film, and a metal layer arranged on the side of the metal oxide layer away from the flexible polymer base film; the flexible polymer base film is selected from at least one of PET, PE, PP, PEN, PPTA, PI, PC, PEEK, POM, PPS, PPO, PVC, PA, and PTFE; the metal oxide layer is selected from at least one of aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, nickel oxide, zinc oxide, aluminum nitride, titanium nitride, titanium carbide, zirconium carbide, silicon nitride, silicon carbide, aluminates, trivalent chromium passivation, and hexavalent chromium passivation; the metal layer is aluminum or copper; the thickness of the metal oxide layer is 1-50 nm, preferably 2-20 nm, and more preferably 3-15 nm; and the thickness of the functional current collector is 3-13 μm.

[0013] In a second aspect, the present application further provides a preparation method of the functional current collector with dual lithium dendrite barrier function, comprising the following steps: S1, plasma surface pretreatment of a flexible polymer base film; S2, preparation of a metal oxide layer on the flexible polymer base film; S3, preparation of a metal layer on the metal oxide layer; S4, preparation of an isolation wall on the metal layer to form a grid structure; and S5, integration of a temperature-sensitive polymer material in the independent unit of the grid structure.

[0014] In a third aspect, the present application further provides an electrode tab, comprising the functional current collector with dual barrier function of lithium dendrite and an active material coated on the surface of the functional current collector.

[0015] In a fourth aspect, the present application further provides a battery, comprising the electrode tab.

[0016] The present application has the following beneficial effects:

[0017] I. Significantly improve the safety of the battery: through the physical-chemical dual barrier mechanism, the growth and expansion of lithium dendrites can be more effectively inhibited, the risk of short circuit of the battery is reduced, and the safety of the lithium battery is significantly improved, and the accidents caused by the safety problem of the battery are reduced.

[0018] II. Enhance the stability of the battery: reduce the damage of lithium dendrites to the internal structure and performance of the battery, which helps to maintain the stability of the battery during the charging and discharging cycle, and improves the cycle life and charging and discharging efficiency of the battery.

[0019] III. Integrated temperature-sensitive polymer material, which will change color when the battery is locally overheated, providing an intuitive, convenient and visual means for battery thermal management and state monitoring, which is convenient for timely discovery of abnormal conditions of the battery and taking corresponding measures. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram of the surface structure of the functional current collector with dual barrier function of lithium dendrite. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant embodiments. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0023] In one aspect of the present application, a functional current collector with dual barrier function of lithium dendrite is provided, comprising a base current collector; such as Figure 1As shown, the current collector surface of the base has a grid structure 1 constructed by insulating partition walls, which enclose a plurality of independent units; and a temperature-sensitive polymer material 2 is integrated in the independent units. At normal working temperature, the temperature-sensitive polymer material is in a stable state and does not affect the normal charging and discharging performance of the battery. When local overheating occurs in the battery, the temperature-sensitive polymer material will rapidly expand and occupy more space in the unit.

[0024] The present application realizes physical-chemical dual barrier to lithium dendrites by constructing a special structure on the current collector surface of the base. Specifically, regarding the physical barrier: the insulating partition walls can physically prevent the lithium dendrites from growing and spreading in a large area on the current collector surface of the base and limit the expansion path of the lithium dendrites. Since the partition walls divide the conductive layer into independent units, the lithium dendrites cannot freely diffuse on the current collector surface, which can greatly reduce the risk of short circuit caused by the lithium dendrites piercing the separator. Regarding the chemical barrier: when the temperature-sensitive polymer material expands due to local overheating of the battery, on the one hand, the expanded polymer material can occupy more space in the unit, further hindering the growth of the lithium dendrites and forming an additional physical barrier; on the other hand, the chemical properties of the temperature-sensitive polymer material may change, which can react with the lithium dendrites and inhibit the continuous growth of the lithium dendrites, realizing the chemical barrier effect.

[0025] In some embodiments, the material of the partition wall is one of nitride, metal oxide, silicon-based ceramic, and carbon-based ceramic; preferably, the nitride is one of boron nitride and aluminum nitride; preferably, the metal oxide is one of aluminum oxide and zirconium oxide; preferably, the silicon-based ceramic is one of silicon nitride and silicon oxide; and preferably, the carbon-based ceramic is silicon carbide.

[0026] In some embodiments, the temperature-sensitive polymer material is one of cross-linked poly(N-isopropylacrylamide) (cross-linked PNIPAM), cross-linked poly(N-isopropylacrylamide) copolymer such as PNIPAM-co-AAc, chitosan-based temperature-sensitive hydrogel, polyacrylamide (PAAm), polyacrylic acid (PAA), polyethylene glycol-polypropylene glycol block copolymer, poly N-vinyl caprolactam (PNVCL), temperature-sensitive polyurethane (TPU), poly(N,N-diethylacrylamide) (PDEA), polyvinyl alcohol (PVA)-based composite, flame retardant wrapping material, conductive-temperature-sensitive composite polymer material such as PTC material, polyethylene oxide-polypropylene oxide block copolymer (PEO-PPO), THFAA copolymer, and thermochromic liquid crystal polymer.

[0027] In some embodiments, the grid structure is composed of hexagonal partition walls and has a honeycomb shape.

[0028] In some embodiments, the length of the side of the independent unit is 20-50 μm, the width of the isolation wall is 0.5-1 μm, and the height of the isolation wall is 1-3 μm.

[0029] In some embodiments, the isolation wall is prepared by photolithography-etching, 3D printing, magnetron sputtering, vacuum evaporation, atomic layer deposition (ALD) or electrochemical method.

[0030] In some embodiments, the base current collector comprises a flexible high polymer base film, metal oxide layers arranged on both sides of the flexible high polymer base film, and a metal layer arranged on the side of the metal oxide layer away from the flexible high polymer base film; the flexible high polymer base film is selected from at least one of PET, PE, PP, PEN, PPTA, PI, PC, PEEK, POM, PPS, PPO, PVC, PA, PTFE; the metal oxide layer is selected from at least one of aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, nickel oxide, zinc oxide, aluminum nitride, titanium nitride, titanium carbide, zirconium carbide, silicon nitride, silicon carbide, aluminum chromate, trivalent chromium passivation, hexavalent chromium passivation; the metal layer is aluminum or copper; the thickness of the metal oxide layer is 1-50 nm, preferably 2-20 nm, and more preferably 3-15 nm; the thickness of the functional current collector is 3-13 μm.

[0031] Another aspect of the present application also provides a preparation method of the functional current collector with the dual barrier function against lithium dendrites, comprising the following steps: S1, plasma surface pretreatment of a flexible high polymer base film; S2, preparation of a metal oxide layer on the flexible high polymer base film; S3, preparation of a metal layer on the metal oxide layer; S4, preparation of an isolation wall on the metal layer to form a grid structure; and S5, integration of a temperature-sensitive polymer material in the independent unit of the grid structure.

[0032] In S2, the metal oxide layer can be prepared by vacuum evaporation coating; in S3, the metal layer can be prepared by vacuum evaporation coating; and in S5, the temperature-sensitive polymer material can be filled in the independent unit by coating.

[0033] Another aspect of the present application also provides an electrode tab comprising the functional current collector with the dual barrier function against lithium dendrites and an active material coated on the surface of the functional current collector.

[0034] Another aspect of the present application also provides a battery comprising the electrode tab.

[0035] The application will be further described in detail in connection with specific examples and comparative examples. The experimental parameters not written in the following specific examples are preferably referred to the guidance given in the present application document, and can also be referred to the experimental manual in the art or other experimental methods known in the art, or the experimental conditions recommended by the manufacturer. It can be understood that the instruments and raw materials used in the following examples are more specific, and in other specific examples, they can not be limited thereto; the weight of the related components mentioned in the examples of the present application specification can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of each component, therefore, as long as the content of the related components according to the examples of the present application specification is enlarged or reduced in proportion, it is within the scope disclosed in the examples of the present application specification.

[0036] Example 1

[0037] The present embodiment provides a functional current collector with dual lithium dendrite barrier function, and the preparation method comprises the following steps:

[0038] S1, select a PET film with a thickness of 6 μm as a base film, place it in the winding system of the vacuum evaporation equipment, pass the base film in the correct direction, then vacuumize the evaporation chamber to ≤9.0×10 -1 Pa. Open the Ar ion source and the winding system switch respectively, and perform plasma surface pretreatment on the base film, wherein the Ar ion source flow rate is set to 100 sccm.

[0039] S2, prepare a metal aluminum oxide layer on the above-mentioned base film by vacuum evaporation coating method, open the oxygen source switch, set the oxygen flow rate to 1000 sccm, maintain the aluminum wire feeding amount at 50 mm / min, and the winding speed at 550 m / min, to prepare the metal aluminum oxide layer.

[0040] S3, evaporate a metal aluminum layer on the above-mentioned metal aluminum oxide layer by vacuum evaporation coating method, wherein the aluminum wire feeding amount is maintained at 400 mm / min, and the winding speed is 250 m / min.

[0041] S4, use a pre-designed hexagonal grid pattern mask, deposit an insulating material by magnetron sputtering method to prepare a hexagonal isolation wall, wherein the insulating material is selected from a silicon nitride target material with a purity of ≥99.99%, the argon flow rate is 80 sccm, the nitrogen flow rate is 20 sccm, and the power is 15 kw.

[0042] S5, dissolve polyacrylamide (PAAm) in water to prepare a solution with a concentration of 10 wt%, use a coating machine for coating, the doctor blade pressure is 0.1 MPa, the coating speed is 200 m / min, and the functional current collector with dual lithium dendrite barrier function is rewound at room temperature.

[0043] Example 2

[0044] The method is basically the same as in Example 1, except that: in S4, silicon carbide is used as the insulating material; and in S5, cross-linked poly(N-isopropylacrylamide) (cross-linked PNIPAM) is used as the temperature-sensitive polymer material.

[0045] Example 3

[0046] The method is basically the same as in Example 1, except that: in S4, the insulating material is alumina; and in S5, the temperature-sensitive polymer material is PNIPAM-co-AAc.

[0047] Example 4

[0048] The method is basically the same as in Example 1, except that: in S4, the insulating material is silicon dioxide; in S5, the temperature-sensitive polymer material is chitosan-based thermosensitive hydrogel.

[0049] Comparative Example 1

[0050] It is basically the same as Example 1, except that the preparation method does not include S5.

[0051] Comparative Example 2

[0052] It is basically the same as Example 1, except that the preparation method does not include S4.

[0053] Comparative Example 3

[0054] It is basically the same as Example 1, except that the preparation method does not include S4 and S5.

[0055] The current collectors prepared in each embodiment and comparative example were tested.

[0056] Battery assembly: For the positive electrode, the current collector used is the current collector prepared in each embodiment and comparative example, and the positive electrode material is 8-series ternary lithium material; for the negative electrode, artificial graphite material is used; for the electrolyte, conventional ternary electrolyte is used, manufactured by Jiangxi Jinhui Lithium Battery Materials Co., Ltd., with the composition of EC / EMC / DMC / LiPF6 and additives.

[0057] Needle penetration test: The equipment uses a benchtop hand press (hydraulic pump with a maximum pressure of 4000 kg, a stroke of 120 mm, and a stroke extension rod of 250 mm), and the steel nail specifications are ( A needle penetration testing machine (100mm long) is used. The battery was punctured with steel nails at a speed of 1 mm / s. Simultaneously, an infrared thermal imager was used to monitor the battery surface temperature; the results are shown in Table 1.

[0058] Table 1 Performance Test Results

[0059] Temperature / °C Example 1 134 Example 2 145 Example 3 152 Example 4 142 Comparative Example 1 177 Comparative Example 2 168 Comparative Example 3 195

[0060] From Table 1, compared with Examples 1-4, Comparative Example 1 only constructed an insulation grid structure on the surface of the base current collector, without integrating the temperature-sensitive polymer material, Comparative Example 2 did not construct an insulation grid structure on the surface of the base current collector, only integrated the temperature-sensitive polymer material, and Comparative Example 3 neither constructed an insulation grid structure nor integrated the temperature-sensitive polymer material, and the needle test results showed that the safety performance and stability thereof were poor. Compared with Comparative Examples 1-3, the functional current collectors prepared in each of the Examples of the present application all had good safety performance and stability, and by constructing the insulation grid structure and integrating the temperature-sensitive polymer material, the lithium dendrites could be effectively blocked.

[0061] The technical features of the above-described embodiments can be combined in any manner, and to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present disclosure.

[0062] The above-described embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims, and the description can be used to explain the content of the claims.

Claims

1. A functional current collector with dual barrier function for lithium dendrite, comprising a base current collector, characterized in that: the surface of the base current collector has a grid structure constructed by insulating partition walls, and the partition walls enclose a plurality of independent units; and a temperature-sensitive polymer material is integrated in the independent units. 2.The functional current collector with dual barrier function for lithium dendrite according to claim 1, characterized in that: the material of the partition wall is one of nitride, metal oxide, silicon-based ceramic, and carbon-based ceramic; preferably, the nitride is one of boron nitride and aluminum nitride; preferably, the metal oxide is one of aluminum oxide and zirconium oxide; preferably, the silicon-based ceramic is one of silicon nitride and silicon oxide; and preferably, the carbon-based ceramic is silicon carbide. 3.The functional current collector with dual barrier function for lithium dendrite according to claim 1, characterized in that: the temperature-sensitive polymer material is one of cross-linked poly (N-isopropyl acrylamide), cross-linked poly (N-isopropyl acrylamide) copolymer, chitosan-based temperature-sensitive hydrogel, polyacrylamide, polyacrylic acid, polyethylene glycol-polypropylene glycol block copolymer, poly N-vinyl caprolactam, temperature-sensitive polyurethane, poly (N, N-diethyl acrylamide), polyvinyl alcohol-based composite, flame retardant wrapping material, conductive-temperature-sensitive composite polymer material, polyethylene oxide-polypropylene oxide block copolymer, THFAA copolymer, and thermochromic liquid crystal polymer. 4.The functional current collector with dual barrier function for lithium dendrite according to claim 1, characterized in that: the grid structure is composed of hexagonal partition walls and has a honeycomb shape. 5.The functional current collector with dual barrier function for lithium dendrite according to claim 1, characterized in that: the length of the side of the independent unit is 20-50 μm, the width of the partition wall is 0.5-1 μm, and the height of the partition wall is 1-3 μm. 6.The functional current collector with dual barrier function for lithium dendrite according to claim 1, characterized in that: the partition wall is prepared by photolithography-etching method, 3D printing, magnetron sputtering, vacuum evaporation, atomic layer deposition (ALD), or electrochemical method. 7.The functional current collector with dual barrier function for lithium dendrite according to claim 1, characterized in that: the base current collector comprises a flexible polymer-based film, a metal oxide layer arranged on both sides of the flexible polymer-based film, and a metal layer arranged on the side of the metal oxide layer away from the flexible polymer-based film; the flexible polymer-based film is selected from at least one of PET, PE, PP, PEN, PPTA, PI, PC, PEEK, POM, PPS, PPO, PVC, PA, and PTFE; the metal oxide layer is selected from at least one of aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, nickel oxide, zinc oxide, aluminum nitride, titanium nitride, titanium carbide, zirconium carbide, silicon nitride, silicon carbide, aluminates, trivalent chromium passivation, and hexavalent chromium passivation; the metal layer is aluminum or copper; the thickness of the metal oxide layer is 1-50 nm; and the thickness of the functional current collector is 3-13 μm. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8. The method for preparing the functional current collector with dual barrier function for lithium dendrite according to any one of claims 1-7, characterized in that it comprises the following steps: S1, plasma surface pretreatment of a flexible high polymer base film; S2, preparation of a metal oxide layer on the flexible high polymer base film; S3, preparation of a metal layer on the metal oxide layer; S4, preparation of a partition wall on the metal layer to form a grid structure; S5, integration of a temperature-sensitive high polymer material in the independent units of the grid structure. The active material coated on the surface of the functional current collector according to any one of claims 1-7.

9. An electrode, characterized by: The electrode sheet according to claim 9.

10. A battery, characterized by: ​

Images