A copper current collector based on snpc-cof modification layer, a preparation method thereof and application in an anode-free lithium metal battery

Abstract

The application provides a copper current collector based on a SnPc-COF modification layer, a preparation method of the copper current collector and application of the copper current collector in an anode-free lithium metal battery, tin phthalocyanine COF (SnPc-COF) is modified to the copper current collector as an artificial modification layer of an anode-free battery current collector to improve lithium deposition and stripping behavior, the thickness of the modification layer is only 2 microns thick, the phthalocyanine polymer skeleton is rich in N atoms, has a strong adsorption effect on lithium ions and can be used as a channel for uniform transmission of lithium ions; meanwhile, Sn 4+ When lithium is deposited, Li-Sn alloy is formed with lithium ions, the nucleation potential of lithium is reduced, and uniform deposition of lithium is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of anode-free battery technology, specifically relating to a copper current collector based on a SnPc-COF modified layer, its preparation method, and its application in anode-free lithium metal batteries. Background Technology

[0002] The rapid development of portable electronics, electric vehicles, and smart grids has greatly driven the demand for high-capacity renewable energy storage systems. However, existing lithium-ion batteries can no longer meet this demand. Lithium metal batteries (LMBs), which use lithium metal as the anode, have attracted much attention due to their ultra-high theoretical specific capacity (3860 mAh / g), and their energy density can be increased by about 50% compared to traditional graphite anodes.

[0003] However, the high reactivity between organic electrolytes and lithium metal limits the practical application of lithium metal anodes, leading to irreversible lithium consumption and excessive electrolyte decomposition. This results in an unfavorable and fragile solid electrolyte interface (SEI), promoting lithium dendrite growth and ultimately causing low coulombic efficiency and shortened cycle life. To compensate for deactivated lithium and achieve better cycle stability, literature reports the use of ultra-thick lithium metal anodes in lithium batteries (LMBs), with lithium content exceeding practical requirements by more than 10 times. However, this results in a significant waste of lithium resources and severely impairs the actual energy density of the LMB, making it unsuitable for practical batteries. In this regard, anode-less LMBs, using lithium-free current collectors, are considered to be the batteries capable of achieving the highest energy density. Anode-less LMBs use copper (Cu) or other non-lithium substrates as the anode, with lithium ions extracted from the cathode material and deposited on the anode during battery charging. However, due to limited lithium sources and substrate incompatibility, anode-less lithium batteries typically form a large number of lithium dendrites and "dead lithium," as well as continuous side reactions with the electrolyte, leading to rapid capacity decay.

[0004] To improve the cycle stability of anode-free lithium batteries, many strategies have been proposed, among which artificial SEI layer interface modification of the current collector is considered one of the most effective. It is well known that lithium deposition on the anode involves three processes: 1) lithium ions penetrate the SEI layer to reach the anode surface; 2) lithium ions are reduced and nucleated on the anode surface; 3) crystal nuclei aggregate and grow. The first two processes are crucial for uniform lithium deposition. However, most current work on anode-free artificial interface layers focuses on only one of these processes. Simply changing the lithium flux does not guarantee a successful nucleation process on the current collector, and the weak adsorption force between the current collector and the nucleus still easily leads to dendrite growth. Simply using alloys to alter the nucleation wettability of lithium metal cannot guarantee uniform lithium flux near the anode, and lithium alloys inevitably come into contact with the electrolyte, forming a fragile SEI layer, which is also detrimental. Therefore, to truly solve the problem of anode-free lithium dendrite formation, focusing on only one process is far from sufficient; it is best to combine two strategies. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing copper current collectors based on SnPc-COF modified layers.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including,

[0009] SnPc-COF and PAN were dissolved in N-methylpyrrolidone at a mass ratio of 3 to 6:1 to obtain a precursor solution with a SnPc-COF concentration of 0.02 to 0.08 mmol / mL.

[0010] After the precursor solution is coated onto the copper foil and then vacuum dried, a copper current collector based on the SnPc-COF modified layer is obtained.

[0011] In a preferred embodiment of the method for preparing copper current collectors based on SnPc-COF modified layers according to the present invention, the coating rotation speed of the precursor liquid is 1000-1500 r / s.

[0012] In a preferred embodiment of the method for preparing copper current collectors based on SnPc-COF modified layers according to the present invention, the vacuum drying temperature is 50-80°C and the drying time is 10-12 hours.

[0013] As a preferred embodiment of the method for preparing the copper current collector based on the SnPc-COF modified layer according to the present invention, the method for preparing the SnPc-COF includes,

[0014] 1,2,4,5-Tetracyanobenzene and tin tetrachloride were dissolved in ethylene glycol at a mass ratio of 2 to 5:1 and ultrasonically mixed until homogeneous. Then, 2 to 6 wt% of a catalyst was added to the mixture and ultrasonic mixing was continued until a milky white solution was formed.

[0015] The milky white solution was placed in a microwave reactor and microwaved to produce a dark green powder. The powder was then washed by reflux using a Soxhlet extractor to obtain SnPc-COF.

[0016] In a preferred embodiment of the method for preparing copper current collectors based on SnPc-COF modified layers according to the present invention, the temperature of the microwave reaction is 160-200℃ and the time is 15-25 min.

[0017] Another object of the present invention is to provide a copper current collector based on a SnPc-COF modified layer.

[0018] Another object of the present invention is to provide an application of a copper current collector based on a SnPc-COF modified layer in the preparation of an anode-free lithium metal battery.

[0019] Another object of the present invention is to provide an anode-free lithium metal battery.

[0020] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including using a copper current collector based on a SnPc-COF modified layer as the anode.

[0021] As a preferred embodiment of the anode-free lithium metal battery of the present invention, the copper current collector based on the SnPc-COF modified layer is pre-plated with lithium.

[0022] As a preferred embodiment of the anode-free lithium metal battery of the present invention, wherein: the anode-free lithium metal battery uses lithium iron phosphate (LiFePO4) as the cathode active material.

[0023] Beneficial effects of this invention:

[0024] This invention modifies copper current collectors with tin phthalocyanine COF (SnPc-COF) as an artificial modification layer for anode-free batteries, improving lithium deposition and stripping behavior. This modified layer is only 2 μm thick. The phthalocyanine polymer backbone is rich in nitrogen atoms, exhibiting strong adsorption with lithium ions and serving as a channel for uniform lithium ion transport. Simultaneously, the Sn in the phthalocyanine... 4+ During lithium deposition, a Li-Sn alloy is formed with lithium ions, which lowers the nucleation potential of lithium and is beneficial for uniform lithium deposition. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0026] Figure 1 The image shows the FT-IR spectrum of SnPc-COF obtained in Example 1 of this invention.

[0027] Figure 2 The image shows the XRD pattern of SnPc-COF obtained in Example 1 of this invention.

[0028] Figure 3 This is a SEM image of the SnPc-COF prepared in Example 1 of the present invention.

[0029] Figure 4 This is a SEM-EDS image of SnPc-COF obtained in Example 1 of the present invention.

[0030] Figure 5 This is a surface SEM image of SP-Cu obtained in Example 1 of the present invention.

[0031] Figure 6 This is a cross-sectional SEM image of SP-Cu obtained in Example 1 of the present invention.

[0032] Figure 7 SEM images of the surface and cross-section of Cu after lithium plating.

[0033] Figure 8 The images show the surface and cross-section SEM images of the SP-Cu after lithium plating obtained in Example 1 of this invention.

[0034] Figure 9 This is a voltage-current cycle curve of the symmetrical battery assembled after pre-lithiation according to the present invention.

[0035] Figure 10 This is a cycle performance diagram of the Li / / Cu half-cell of the present invention.

[0036] Figure 11 This is a cyclic stability diagram of SP-Cu-Li / / Li-SP-Cu of the present invention.

[0037] Figure 12 This is a cycle stability diagram of the SP-Cu-Li / / LFP full cell of the present invention.

[0038] Figure 13 This is a comparison of the performance of Li / / Cu half-cells prepared with different SnPc-COF concentrations in the precursor solution in Example 2 of the present invention.

[0039] Figure 14 This is a comparison of the electrochemical performance of Li / / Cu half-cells assembled with Cu current collectors of different modified layers prepared in Example 1 and Comparative Examples 2-4. Detailed Implementation

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0041] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0042] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0043] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.

[0044] In this invention, the current collector is assembled into a half-cell or a full-cell when its performance is tested. Specifically, the assembly of the cell is carried out according to the following method:

[0045] Preparation of cathode electrode sheet:

[0046] 10 wt.% of polyvinylidene fluoride (PVDF) was weighed into a 5 mL sample vial, and NMP was added until the PVDF was completely dissolved into a colorless, transparent, viscous liquid. 80 wt.% of lithium iron phosphate (LiFePO4) (LFP) powder and 10 wt.% of conductive carbon black (Super P) were weighed and thoroughly ground. The mixed powder was then transferred to a glass sample vial containing 5 mL of the colorless, transparent, viscous liquid. After magnetic stirring and dispersion for 12 hours, the slurry was poured onto an aluminum foil current collector. The active material loading was prepared to be approximately 2.5 mg / cm³ by adjusting the doctor blade graduations matched to the MSK-AFA-1 type coating applicator. -2 The electrode sheet was vacuum dried at 80℃ for 1000 min and then cut into circular electrode sheets with a diameter of 12 mm to serve as LFP cathode electrode sheets.

[0047] Assemble the battery:

[0048] Half battery:

[0049] Assembled in a CR2025 coin cell, the coin cell consists of a 14mm diameter lithium foil, a glass fiber separator, 80μL of electrolyte (1M LiTFSI, DOL:DME = 1:1 vol%), and a Cu current collector, thus obtaining a Li / / Cu battery.

[0050] The assembled batteries were left to stand at 60℃ for 10 hours to fully activate them. Then, charge-discharge tests were performed on a battery tester (Land CT2001A), with both charge and discharge current densities at 1 mA cm⁻¹. -2 Discharge for 1 hour, then charge to 0.1V.

[0051] Full battery:

[0052] Pre-plating 5mAh cm⁻¹ onto Cu / Cu current collector -2 The lithium-ion battery was then assembled with an LFP cathode to form a solid-state battery. The battery was cycled at 0.5C in the 2.5–4V range to test the cycle stability of the anode-free battery.

[0053] Example 1

[0054] This embodiment provides a method for preparing SnPc-COF modified copper current collectors, specifically:

[0055] 1) Synthesis of SnPc-COF:

[0056] 0.3563g of 1,2,4,5-tetracyanobenzene (TCBN) and 0.1g of tin tetrachloride were dissolved in 20ml of ethylene glycol and ultrasonically mixed until homogeneous. Then, 0.8ml of catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was added and ultrasonically mixed for 15min until a milky white solution was formed.

[0057] The milky white solution was placed in a microwave reactor and reacted at 180°C for 15 minutes. The resulting dark green powder was then washed by reflux using a Soxhlet extractor for two days to obtain SnPc-COF.

[0058] Figure 1 The FT-IR spectrum of SnPc-COF shows that the original sample was located at 2246.37 cm⁻¹. -1 The disappearance of the cyano peak was followed by the appearance of a peak at 1649.98 cm⁻¹ in the reaction product. -1 The stretching vibration peak of the C=N bond is located at 1316.23 cm⁻¹, the same as that of the CN bond. -1 With 1064.47cm -1 The bending and stretching vibration peaks indicate that tetracyanobenzene has successfully reacted and polymerized to form phthalocyanine COF.

[0059] The structure of SnPc-COF was analyzed by powder X-ray diffraction (PXRD), and the results are as follows: Figure 2 As shown, the XRD pattern shows a distinct small-angle diffraction peak at around 8.42°, which is a characteristic signal of COF, indicating that it has an ordered layered two-dimensional (2D) structure. This is conducive to the formation of vertical lithium-ion transport channels and promotes the efficient short-range transport of lithium ions.

[0060] The morphology, size, and elemental distribution of SnPc-COF were investigated using SEM, such as... Figure 3 As shown, SnPc-COF exhibits irregular solid particles overall, and the synthesized solid particles are relatively uniform in size, around 1 μm.

[0061] Next, EDS elemental analysis was performed on SnPc-COF, from... Figure 4 The mapping diagram shows that Sn and N elements are evenly distributed, which proves the synthesis of SnPc-COF.

[0062] 2) Preparation of SnPc-COF@Cu (SP-Cu):

[0063] 20 mg SnPc-COF and polyacrylonitrile (PAN) were dissolved in 1 ml of N-methylpyrrolidone at a mass ratio of 4:1 and mixed evenly to prepare a precursor solution with a SnPc-COF concentration of 0.04 mmol / mL.

[0064] Using a spin coater, the precursor solution was coated onto copper foil at a speed of 1500 r / s. The coated copper foil was then placed in a vacuum oven and dried at 80°C for 12 h to obtain SnPc-COF@Cu.

[0065] Figure 5 Here is a surface SEM image of SP-Cu, from Figure 5As can be seen, the original brownish-red copper foil surface is covered with green phthalocyanine. Local magnification observation of the modified copper foil surface using SEM reveals that the copper foil surface is covered by a coating, with SnPc-COF encapsulated within PAN, uniformly covering the copper foil surface. Cutting and observing the cross-section of the SP-Cu reveals the following results: Figure 6 As shown, Figure 6 The SEM image clearly shows a 2μm thick coating on the copper surface, which proves the successful coating of the modification layer.

[0066] Comparative Example 1

[0067] This comparative example uses bare copper (without any modifications) as a reference.

[0068] The SnPc-COF@Cu from Example 1 and bare copper from Comparative Example 1 were assembled into half-cells and full-cells for performance testing. Before the test, 5mAh cm⁻¹ was deposited on bare Cu and SnPc-COF@Cu, respectively. -2 The surface and cross-sectional morphology of the lithium deposits were observed using SEM to illustrate the lithium deposition. The results are as follows: Figure 7 , Figure 8 As shown, from Figure 7 The planar SEM images show that lithium on bare Cu is in a loose, banded formation, indicating that the adsorption energy between Cu and lithium is low. Therefore, lithium cannot be uniformly and densely deposited on copper, often leading to dendrite formation or even dead lithium deposits. In contrast, lithium on SnPc-COF@Cu is densely deposited on copper with almost no voids. Figure 8 The image also shows that lithium is deposited beneath the coating, indicating that lithium ions are redeposited through the modification layer. The coating is crucial for the uniform transport and deposition of lithium ions. Comparing the lithium layer thickness on SnPc-COF@Cu and bare Cu, the lithium deposited on SnPc-COF@Cu is thinner and denser, demonstrating that the successful modification of the copper foil with the SP-COF coating improves the poor compatibility between the copper foil and lithium.

[0069] Figure 9 The CV curves reveal the kinetics of Li deposition / dissolution on Cu, showing a significant increase in the current response of the SnPc-COF@Cu electrode, exhibiting rapid charge transfer and reversible reaction kinetics. Therefore, the presence of the SnPc-COF@Cu coating can lead to rapid and uniform charge transfer, which will promote the uniform deposition of lithium ions on copper.

[0070] The Li / / Cu half-cell was assembled for performance testing. Generally, anode-less batteries experience rapid coulombic efficiency degradation due to their limited lithium source. Figure 10It was found that the coulombic efficiency of bare copper indeed decays rapidly, only achieving stable cycling for about 20 cycles, and dropping to near zero in less than 50 cycles. This is because copper has poor wettability for lithium, easily forming dendrites and dead lithium during lithium deposition and stripping. Furthermore, the deposited lithium readily reacts with the electrolyte, consuming a large amount of electrolyte. However, using the modified SP-Cu current collector, stable cycling for over 400 cycles was achieved, with coulombic efficiencies consistently above 99%. This indicates that the SP-COF coating significantly improves lithium deposition and stripping.

[0071] Pre-lithiation of SP-Cu current collector / bare copper followed by assembly into a full cell (symmetric cell) Li / / SP-Cu Figure 11 The test results of SPCu-Li / / Li-SP-Cu symmetric cells show that the symmetric cells assembled with SP-Cu current collectors can cycle stably for more than 2000 hours, indicating good stability during lithium deposition and stripping.

[0072] Figure 12 The capacity of the anode-less full cell assembled with bare Cu foil decays rapidly, decreasing quickly in the first 50 cycles and approaching zero by the 100th cycle. In contrast, the full cell assembled with SP-Cu current collector maintains a stable capacity curve after 170 cycles, retaining over 85% of its capacity. This indicates that the modified SP-Cu current collector significantly improves the lithium compatibility of Cu foil, making long-term stable cycling of anode-less batteries possible.

[0073] Example 2

[0074] The difference between this embodiment and Embodiment 1 is that the concentration of the precursor solution in step 2) is adjusted. Specifically, the concentration of SnPc-COF in the precursor solution is adjusted to 0.02, 0.04, 0.06, and 0.08 mmol / mL, respectively.

[0075] The remaining steps were the same as in Example 1, and copper current collectors with different concentrations of modified layers were obtained in this comparative example. These were then assembled into Li / / Cu half-cells, and their electrochemical performance was compared. The results are as follows: Figure 13 As shown.

[0076] from Figure 13It can be seen that when the SnPc-COF precursor concentration is 0.02 mmol / mL, the Li / / Cu battery can cycle stably for about 175 cycles. When the SnPc-COF concentration is increased to 0.04 mmol / mL, the battery stability is further improved, and it can cycle stably for more than 270 cycles. However, further increasing the concentration leads to a decrease in battery stability. The Li / / Cu half-cells prepared with precursor concentrations of 0.06 mmol / mL and 0.08 mmol / mL can only cycle for about 100 and 50 cycles, respectively. This proves that the modification layer on the Cu foil should not be too thick, otherwise its conductivity will deteriorate, thus affecting the battery performance.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 1 is that only Sn is used. 4+ Modification of Cu current collectors, specifically:

[0079] Tin tetrachloride was dissolved in N-methylpyrrolidone and mixed thoroughly to prepare a precursor solution with a concentration of 0.04 mmol / mL;

[0080] The precursor solution was coated onto copper foil using a spin coater at 1500 rpm. The coated copper foil was then dried in a vacuum oven at 80°C for 12 hours to obtain Sn. 4+ -Cu.

[0081] Comparative Example 3

[0082] The difference between this comparative example and Example 1 is that only the Cu current collector is modified with phthalocyanine COF. Specifically:

[0083] 1,2,4,5-Tetracyanobenzene (TCBN) was dissolved in N-methylpyrrolidone and mixed thoroughly to prepare a precursor solution with a concentration of 0.04 mmol / mL;

[0084] Using a spin coater, the precursor solution was coated onto copper foil at a speed of 1500 r / s. The coated copper foil was then placed in a vacuum oven and dried at 80°C for 12 h to obtain Pc-Cu.

[0085] Comparative Example 4

[0086] The difference between this comparative example and Example 1 is that only the Cu current collector modified with PAN is used. Specifically:

[0087] Polyacrylonitrile (PAN) was dissolved in N-methylpyrrolidone and mixed thoroughly to prepare a precursor solution with a concentration of 0.04 mmol / mL;

[0088] Using a spin coater, the precursor solution was coated onto copper foil at a speed of 1500 r / s. The coated copper foil was then placed in a vacuum oven and dried at 80°C for 12 h to obtain PAN-Cu.

[0089] The Cu current collectors with different modified layers prepared in Comparative Examples 2-4 were assembled into Li / / Cu half-cells, and their electrochemical performance was measured. The results are as follows: Figure 14 As shown, bare copper (Bare Cu) without any modification layer can only cycle stably for about 20 cycles, and its coulombic efficiency drops rapidly after 40 cycles. Copper foil modified only with tin ions and metal-free phthalocyanine (COF) shows a slight improvement in performance, with its coulombic efficiency remaining stable at around 98% before 80 cycles, after which it becomes extremely unstable. PAN-modified copper foil can only cycle stably for 180 cycles. Copper foil modified with tin phthalocyanine and the binder PAN exhibits the best performance, capable of cycling stably for over 400 cycles.

[0090] Therefore, it can be concluded that having only one of the metals or polymers in the modification layer is insufficient. Metal ions alone will result in an unstable alloy that reacts with the solution at the interface, forming a fragile SEI layer. Polymer coatings alone can only prevent direct contact with the solution and accelerate lithium-ion transport, but they cannot regulate nucleation behavior, resulting in uneven lithium-ion deposition on copper. Only the synergistic effect of both metal ions and polymers can achieve the best results.

[0091] In summary, this invention modifies copper current collectors with tin phthalocyanine COF (SnPc-COF) as an artificial modification layer for anode-free batteries, improving lithium deposition and stripping behavior. This modification layer is only 2 μm thick. The phthalocyanine polymer backbone is rich in nitrogen atoms, exhibiting strong adsorption with lithium ions and serving as a channel for uniform lithium ion transport; simultaneously, the Sn atoms in the phthalocyanine... 4+ During lithium deposition, a Li-Sn alloy is formed with lithium ions, which lowers the nucleation potential of lithium and is beneficial for uniform lithium deposition.

[0092] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a copper current collector based on a SnPc-COF modified layer, characterized in that: include, SnPc-COF and PAN were dissolved in N-methylpyrrolidone at a mass ratio of 3 to 6:1 to obtain a precursor solution with a SnPc-COF concentration of 0.04 mmol / mL. After the precursor solution is coated onto the copper foil and then vacuum dried, a copper current collector based on the SnPc-COF modified layer is obtained, wherein the thickness of the SnPc-COF modified layer is 2μm.

2. The method for preparing a copper current collector based on a SnPc-COF modified layer as described in claim 1, characterized in that: The coating rotation speed of the precursor liquid is 1000~1500 r / s.

3. The method for preparing a copper current collector based on a SnPc-COF modified layer as described in claim 1, characterized in that: The vacuum drying temperature is 50~80 ℃, and the drying time is 10~12 h.

4. The method for preparing a copper current collector based on a SnPc-COF modified layer as described in claim 1, characterized in that: The preparation method of SnPc-COF includes, 1,2,4,5-Tetracyanobenzene and tin tetrachloride were dissolved in ethylene glycol at a mass ratio of 2 to 5:1 and ultrasonically mixed until homogeneous. Then, 2 to 6 wt% of a catalyst was added to the mixture and ultrasonic mixing was continued until a milky white solution was formed. The milky white solution was placed in a microwave reactor and microwaved to produce a dark green powder. The powder was then washed by reflux using a Soxhlet extractor to obtain SnPc-COF.

5. The method for preparing a copper current collector based on a SnPc-COF modified layer as described in claim 4, characterized in that: The microwave reaction is carried out at a temperature of 160~200℃ for 15~25 minutes.

6. The copper current collector based on the SnPc-COF modified layer prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the copper current collector based on the SnPc-COF modified layer as described in claim 6 in the preparation of anode-free lithium metal batteries.

8. An anode-free lithium metal battery, characterized in that: The copper current collector based on the SnPc-COF modified layer as described in claim 6 is used as the anode.

9. The anode-free lithium metal battery as described in claim 8, characterized in that: The copper current collector based on the SnPc-COF modified layer is subjected to pre-lithium plating treatment.

10. The anode-free lithium metal battery as described in claim 8, characterized in that: The anode-free lithium metal battery uses lithium iron phosphate (LiFePO4) as the cathode active material.

Images