A lithium negative electrode artificial interface layer, a preparation method and application thereof

Abstract

This invention belongs to the field of electrochemical energy storage materials and devices, specifically relating to an artificial interface layer for lithium anodes, its preparation method, and its application. The artificial interface layer for lithium anodes provided by this invention comprises a composite of transition metal nanoparticles and carbon, and a fluoropolymer. It solves the problem in existing technologies where the use of low-ionic-conductivity organic binders in artificial SEI layers leads to slow lithium-ion transport kinetics at the interface, making it difficult to balance high mechanical strength and rapid ion transport. This results in an artificial interface layer with excellent rate performance and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage materials and devices, specifically relating to an artificial interface layer for lithium anodes, its preparation method, and its application. Background Technology

[0002] With the rapid development of portable electronic devices and the electric vehicle industry, the market is placing increasing demands on the energy density of rechargeable batteries. Against this backdrop, lithium metal batteries have gained popularity due to the ultra-high theoretical specific capacity (~3860 mAh·g) of lithium metal anodes. -1 It has extremely low electrochemical potential (~3.04 V vs. SHE) and low density (0.59 g·cm³). -3 Lithium metal anodes are considered a strong candidate for next-generation high-energy-density energy storage systems. However, the commercial application of lithium metal anodes still faces severe challenges. The inherent infinite volume change and uneven lithium deposition behavior of lithium metal batteries during cycling can induce uncontrolled growth of lithium dendrites. This not only punctures the separator and causes safety hazards, but also leads to repeated rupture and reconstruction of the solid electrolyte interface film, continuously consuming electrolyte and active lithium, ultimately resulting in low coulombic efficiency and a sharp decline in cycle life.

[0003] Constructing a high-performance solid-state electrolyte interphase (SEI) film is widely recognized as one of the keys to stabilizing lithium metal anodes. An ideal SEI film should possess at least the following characteristics: (1) excellent chemical and electrochemical stability to suppress the continuous occurrence of side reactions; (2) sufficient mechanical strength to effectively hinder lithium dendrite growth and puncture; and (3) excellent lithium-ion conductivity to ensure low polarization potential and rapid interfacial kinetics. Pre-constructing an artificial SEI layer on the lithium metal surface allows for precise control of its composition and structure, which is an effective way to achieve the above goals. For example, introducing inorganic nanomaterials (such as Al2O3 and ZrO2) can significantly enhance the mechanical modulus of the SEI layer; while introducing lithiophilic components has been shown to guide the uniform nucleation and deposition of lithium.

[0004] Drop-coating is widely used for the preparation of artificial SEI layers due to its low cost, simple process, and ease of integration with existing electrode manufacturing processes. However, the inherent ionic conductivity of the organic polymer binders (such as polyvinylidene fluoride) commonly used in this method is much lower than that of inorganic fast ion conductors, which severely restricts the lithium-ion transport kinetics of the overall interface layer and limits the improvement of battery rate performance and cycle stability. Therefore, developing a novel artificial interface layer that can simultaneously achieve fast ion transport and high mechanical stability is of vital importance for promoting the development of high-performance lithium metal batteries. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an artificial interface layer for lithium anodes, its preparation method and application. The artificial interface layer for lithium anodes provided by the present invention can solve the problem in the prior art that the use of low ionic conductivity organic binders in artificial SEI layers leads to slow interfacial lithium-ion transport dynamics and difficulty in balancing high mechanical strength and fast ion transport, and has excellent rate performance and cycle stability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an artificial interface layer for lithium anodes, comprising a composite of transition metal nanoparticles and carbon and a fluorinated polymer.

[0007] Preferably, the composite of the transition metal nanoparticles and carbon has at least one of the following structures: nanocage structure, hollow structure, porous structure, solid spherical structure, and sheet structure.

[0008] Preferably, the transition metal in the transition metal nanoparticles includes at least one of nickel, cobalt, and iron.

[0009] Preferably, the fluoropolymer is polyvinylidene fluoride.

[0010] Preferably, the mass ratio of the transition metal nanoparticle-carbon composite to the fluoropolymer is 1:9 to 8:2.

[0011] Preferably, the thickness of the lithium anode artificial interface layer is 0.5~10μm.

[0012] This invention also provides a method for preparing the artificial interface layer of the lithium anode described in the above technical solution, comprising the following steps: In a protective gas atmosphere, a complex of transition metal nanoparticles and carbon, a fluoropolymer, and a polar organic solvent are mixed and ultrasonicated to obtain a suspension slurry. The suspension slurry is coated onto the substrate surface and dried to obtain an artificial interface layer for the lithium anode.

[0013] The present invention also provides a lithium metal anode, comprising a lithium metal substrate and an artificial interface layer covering at least one surface of the lithium metal substrate; The artificial interface layer is the lithium anode artificial interface layer described in the above technical solution or the lithium anode artificial interface layer prepared by the preparation method described in the above technical solution.

[0014] The present invention also provides the application of the lithium anode artificial interface layer described in the above technical solution, or the lithium anode artificial interface layer prepared by the preparation method described in the above technical solution, or the lithium metal anode described in the above technical solution, in electrochemical devices.

[0015] Preferably, the electrochemical device is a battery; the battery is a lithium metal battery, a lithium-sulfur battery, or a lithium-air battery.

[0016] This invention provides an artificial interface layer for lithium anodes, comprising a composite of transition metal nanoparticles and carbon and a fluorinated polymer.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) By utilizing the catalytic activity of transition metal nanoparticles (such as Ni), low ionic conductivity organic binder-fluorinated polymer is converted in situ into high ionic conductivity inorganic LiF phase, which fundamentally solves the constraint of organic matter on interfacial ion transport and realizes uniform and dense deposition of lithium.

[0018] (2) The physical transport channels provided by the composite (such as nanocage-like Ni / C) work synergistically with the in-situ generated LiF fast ion conductor to jointly construct an ultrafast lithium ion transport interface, which significantly reduces the interface impedance and electrochemical polarization.

[0019] (3) The composite interface layer acts as a physical barrier, which greatly reduces the decomposition of the electrolyte, suppresses side reactions, and extends the battery cycle life.

[0020] (4) Thanks to the above synergistic effect, the artificial interface layer of the present invention brings a breakthrough performance improvement to the lithium metal anode, exhibiting ultra-long cycle life and excellent rate performance in both symmetric cells and full cells. Attached Figure Description

[0021] Figure 1 X-ray diffraction pattern of the nanocage-like Ni / C particles prepared in Example 1; Figure 2 The images are transmission electron microscope (TEM) images of the nanocage-like Ni / C particles prepared in Example 1, where (a) and (b) are the particle morphology of Ni / C under low magnification, (c) is the lattice spacing of Ni / C particles under high magnification, and (d) is the corresponding selected electron diffraction. Figure 3 (a) Nitrogen adsorption-desorption isotherm and (b) corresponding pore size distribution curve of the nanocage-like Ni / C particles prepared in Example 1. Figure 4 Scanning electron microscope (SEM) image of the Ni / C artificial interface layer modified lithium anode prepared in Example 2; Figure 5 Fourier transform infrared spectrum of the Ni / C@Li anode interface layer prepared in Example 2 during the drying process as a function of time; Figure 6 The graph shows a comparison of the cycle performance of the Li‖Li symmetric cells assembled with Ni / C@Li in Example 2, PVDF@Li in Comparative Example 1, and Bare Li anode in Comparative Example 2. Figure 7 The images are SEM images of Ni / C@Li in Example 2 and Bare Li in Comparative Example 2 after cycling, where (a) is a SEM image of the surface of Ni / C@Li negative electrode, (b) is a SEM image of the cross-section of Ni / C@Li negative electrode, (c) is a SEM image of the surface of Bare Li negative electrode, and (d) is a SEM image of the cross-section of Bare Li negative electrode. Figure 8 This is a comparison chart of the long-cycle performance of the full cells assembled with NCM622 cathodes in Example 2 (Ni / C@Li) and Comparative Example 2 (Bare Li). Figure 9 The circuit performance of a pouch cell assembled with a 30 μm Ni / C@thin Li anode and an NCM811 cathode prepared using the method in Example 2 is shown in the figure. Figure 10 The graph shows the cycle performance of a lithium-sulfur pouch cell assembled with a 30μm Ni / C@thin Li anode and a sulfur cathode, prepared using the method in Example 2. Detailed Implementation

[0022] This invention provides an artificial interface layer for lithium anodes, comprising a composite of transition metal nanoparticles and carbon and a fluorinated polymer.

[0023] Unless otherwise specified, the present invention does not have special requirements on the source of raw materials used, and commercially available products well known to those skilled in the art can be used.

[0024] As one embodiment, the composite of transition metal nanoparticles and carbon has at least one of the following: nanocage structure, hollow structure, porous structure, solid spherical structure, and sheet structure, with a specific embodiment being a nanocage structure or a hollow structure.

[0025] In one embodiment, the transition metal nanoparticles contain at least one of nickel, cobalt, and iron, with nickel being the most specific in this embodiment.

[0026] As one embodiment, the preparation method of the complex of transition metal nanoparticles and carbon includes the following steps: mixing metal-organic framework material, transition metal salt and organic solvent for loading, and then washing, solid-liquid separation and drying in sequence to obtain nanocage precursor; The nanocage precursor was sintered in a protective gas to obtain a composite of transition metal nanoparticles and carbon.

[0027] As one embodiment, the metal-organic framework material is a ZIF67@ZIF8 template; the preparation method of the ZIF67@ZIF8 template includes the following steps: dissolving 2-methylimidazole, cobalt salt, and zinc salt in methanol, stirring at room temperature, and separating the solid and liquid to obtain the ZIF67@ZIF8 template; the cobalt salt is cobalt nitrate; the zinc salt is zinc nitrate; the mass ratio of 2-methylimidazole, cobalt salt, and zinc salt is 1~3:1~3:1~3, and in a specific embodiment it is 2.364:2.184:2.233; the 2- The mass ratio of methylimidazole to methanol is 1-3 g:120 mL, specifically 2.364 g:120 mL in this embodiment; the stirring speed at room temperature is 100-600 rpm, specifically 300-500 rpm in this embodiment, and the stirring time is 40-50 min, specifically 45 min in this embodiment; the solid-liquid separation is performed by centrifugation; the centrifugation speed is 5000-8000 rpm, specifically 6000 rpm in this embodiment, and the centrifugation time is 30-60 min, specifically 40 min in this embodiment.

[0028] In one embodiment, the transition metal salt includes a nitrate; the organic solvent is ethanol; the mass ratio of the metal-organic framework material to the transition metal salt is 0.1~0.3:0.2~0.5, specifically 0.2:0.45 in this embodiment; the mass ratio of the metal-organic framework material to the volume ratio of the organic solvent is 0.1~0.3g:50mL, specifically 0.2g:50mL in this embodiment; the mixing of the metal-organic framework material, the transition metal salt, and the organic solvent is performed by dispersing the metal-organic framework material in an organic solvent containing the transition metal salt; the loading is carried out under stirring conditions. The stirring rate is 100-600 rpm, specifically 300 rpm in this embodiment, and the time is 50-70 min, specifically 60 min in this embodiment; the washing is rinsing; the washing reagent is an ethanol solution; the solid-liquid separation is centrifugation; the centrifugation temperature is room temperature, the rotation speed is 5000-8000 rpm, specifically 6000 rpm in this embodiment, and the time is 8-15 min, specifically 10 min in this embodiment; the drying temperature is 100-120℃, specifically 120℃ in this embodiment, and the time is 10-14 h, specifically 12 h in this embodiment.

[0029] In one embodiment, the sintering equipment is a tube furnace; the protective gas is argon; the sintering temperature is 650~800℃, specifically 700℃ in this embodiment, and the holding time is 1~3h, specifically 2h in this embodiment; after sintering, the process further includes: natural cooling to room temperature.

[0030] In one embodiment, the fluoropolymer is polyvinylidene fluoride; the mass ratio of the transition metal nanoparticles and carbon composite to the fluoropolymer is 1:9 to 8:2, and in a specific embodiment it is 8:2.

[0031] In one implementation, the thickness of the lithium anode artificial interface layer is 0.5~10μm, and in a specific embodiment it is 1~5μm.

[0032] In this invention, transition metal nanoparticles can catalyze the breaking of CF bonds in fluoropolymers, thereby generating a LiF-rich fast ion transport interface in situ on the surface of the lithium metal anode.

[0033] This invention also provides a method for preparing the artificial interface layer of the lithium anode described in the above technical solution, comprising the following steps: In a protective gas atmosphere, a complex of transition metal nanoparticles and carbon, a fluoropolymer, and a polar organic solvent are mixed and ultrasonicated to obtain a suspension slurry. The suspension slurry is coated onto the substrate surface and dried to obtain an artificial interface layer for the lithium anode.

[0034] In one embodiment, the protective gas is argon, specifically a glove box filled with argon, wherein the water and oxygen contents are both less than 0.1 ppm; the polar organic solvent is N-methylpyrrolidone; the mass ratio of the fluoropolymer to the volume of the polar organic solvent is (2~20.0) mg:1.0 mL, specifically 10.0 mg:1.0 mL in this embodiment; the ultrasonication time is ≥5 h, specifically 6 h in this embodiment; the coating is drop coating; the drying temperature is 70~90℃, specifically 80℃ in this embodiment, and the drying time is 30~60 min, specifically 40 min in this embodiment.

[0035] The present invention also provides a lithium metal anode, comprising a lithium metal substrate and an artificial interface layer covering at least one surface of the lithium metal substrate; The artificial interface layer is the lithium anode artificial interface layer described in the above technical solution or the lithium anode artificial interface layer prepared by the preparation method described in the above technical solution.

[0036] In one embodiment, the lithium metal substrate is a commercial lithium foil; the preparation method of the lithium metal anode is the same as the preparation method of the lithium anode artificial interface layer, except that the substrate used is replaced with a lithium metal substrate, which will not be described in detail here.

[0037] The artificial interface layer for lithium anodes provided by this invention, when coated onto the surface of lithium metal, can utilize the catalytic breaking effect of transition metals (such as Ni) on the CF bonds in fluorinated polymers to generate a fast-ion conductor phase rich in lithium fluoride in situ at the interface, thereby constructing a high-speed lithium-ion transport channel. The artificial interface layer of this invention can effectively accelerate lithium-ion desolvation, homogenize lithium-ion flux, reduce lithium nucleation overpotential, and inhibit lithium dendrite growth, significantly improving the cycle stability of lithium metal batteries. When applied to lithium symmetric batteries, it can achieve a cycle stability of 5 mA·cm⁻¹. -2 / 5mAh·cm -2 It can withstand stable cycling for more than 1600 hours; the full cell assembled with NCM622 cathode still maintains excellent capacity retention after 800 cycles at 0.5C rate.

[0038] The present invention also provides the application of the lithium anode artificial interface layer described in the above technical solution, or the lithium metal anode described in the above technical solution, or the lithium metal anode described in the above technical solution in electrochemical devices.

[0039] In one embodiment, the electrochemical device is a battery; the battery is a lithium metal battery, a lithium-sulfur battery, or a lithium-air battery.

[0040] In one embodiment, the electrolyte in the lithium metal battery comprises a solvent and a lithium salt; the solvent is a mixed solvent of 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME), or a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC); the lithium salt comprises LiTFSI and LiNO3, or LiPF6. In this embodiment, the electrolyte in the lithium metal battery is a mixed solvent of DOL and DME containing 1.0 M LiTFSI and 0.2 M LiNO3, or a mixed solvent of EC and DEC containing 1.0 M LiPF6; the positive electrode in the lithium metal battery comprises LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622) or LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811).

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1 The specific steps for preparing nanocage-like Ni / C particles are as follows: (1) Dissolve 2.364 g 2-methylimidazole, 2.184 g cobalt nitrate hexahydrate and 2.233 g zinc nitrate hexahydrate in 120 mL methanol, stir at 300 rpm for 45 min at room temperature, and obtain ZIF67@ZIF8 template by centrifugation at 6000 rpm for 40 min; (2) Disperse 0.2g of the above ZIF67@ZIF8 template in 50mL of ethanol solution containing 0.45g of nickel nitrate hexahydrate, stir at 300rpm for 60min, then wash with ethanol solution, centrifuge at 6000rpm for 10min, and dry at 120℃ for 12h to obtain nanocage precursor; (3) The dried nanocage precursor was transferred to a tube furnace and heated to 700°C at a heating rate of 2°C / min under an argon atmosphere. The temperature was maintained at this temperature for 2 hours and then naturally cooled to room temperature. The resulting black powder product was the nanocage-shaped Ni / C particles.

[0043] Example 2 The construction of the Ni / C artificial interface layer and the preparation of the Ni / C@Li anode are detailed in the following steps: (1) In a glove box filled with argon (water and oxygen content are both below 0.1 ppm), weigh 40.0 mg of the nanocage-shaped Ni / C particles prepared in Example 1 and 10.0 mg of polyvinylidene fluoride powder (mass ratio 8:2), add them to 1.0 mL of N-methylpyrrolidone solvent, and sonicate the mixture for 6 h to form a uniform and stable suspension slurry. (2) Using a pipette, 50.0 μL of the above slurry was drawn and uniformly dropped onto the surface of a commercial lithium foil. Then, the coated lithium foil was dried at 80 °C for 40 min to completely remove the NMP solvent, and a lithium anode modified with a Ni / C artificial interface layer was obtained, denoted as Ni / C@Li.

[0044] Comparative Example 1 To prepare a lithium anode containing only a PVDF protective layer, 10.0 mg of PVDF powder was weighed and dissolved in 1.0 mL of NMP solvent to form a homogeneous solution. The subsequent coating and drying steps were the same as in Example 2, and the resulting anode was denoted as PVDF@Li.

[0045] Comparative Example 2 For comparison, we used commercially available lithium foil that had not undergone any treatment, denoted as Bare Li.

[0046] Performance testing (1) Figure 1 The image shows the X-ray diffraction pattern of the nanocage-like Ni / C particles prepared in Example 1. It can be seen that the prepared Ni / C material is composed of graphitic carbon and metallic nickel.

[0047] (2) Figure 2 The images show transmission electron microscopy (TEM) images of the nanocage-like Ni / C particles prepared in Example 1. (a) and (b) show the particle morphology of Ni / C under low magnification, (c) shows the lattice spacing of Ni / C particles under high magnification, and (d) shows the corresponding selected electron diffraction. It can be seen that the Ni / C particles are nanocage-like with a diameter of about 500 nm. The outer shell of the nanocage is composed of graphite carbon and uniformly distributed metallic Ni nanoparticles.

[0048] (3) Figure 3 The figures show (a) the nitrogen adsorption-desorption isotherm and (b) the corresponding pore size distribution curve of the nanocage-like Ni / C particles prepared in Example 1. As can be seen from the figures, the pore size of the Ni / C material is approximately 3.9 nm, and its specific surface area is as high as 99.26 m². 2 / g, can be Li + Fast transmission provides ample bandwidth.

[0049] (4) Figure 4 The image shows a scanning electron microscope (SEM) image of the lithium anode modified with the Ni / C artificial interface layer prepared in Example 2. It can be seen that the Ni / C particles are densely and uniformly packed on the lithium metal surface, and the thickness of the artificial interface layer is about 3.4 μm.

[0050] (5) Analysis of interfacial layer composition and catalytic process The chemical evolution of the Ni / C@Li anode interface layer prepared in Example 2 during the drying process was monitored using Fourier transform infrared spectroscopy (FTIR). Figure 5 As shown.

[0051] from Figure 5 As can be seen from this, the spectrum located at 1400 cm⁻¹ -1 and 1180cm -1 The characteristic peaks at 3680 cm⁻¹ are attributed to the bending and stretching vibrations of the CF bond, respectively. -1 The strong peak at this point corresponds to the symmetric stretching vibration of LiF. With prolonged drying time, the intensity of the CF bond characteristic peak gradually weakens, while the intensity of the LiF characteristic peak simultaneously increases. This trend directly confirms that Ni nanoparticles can effectively catalyze the breaking of CF bonds in PVDF, thereby reacting with metallic lithium to generate LiF. This result strongly supports the regulatory mechanism proposed in this invention for "converting low-ionic-conductivity organic polymers into high-ionic-conductivity inorganic phases."

[0052] (6) Electrochemical performance of symmetrical cells The Ni / C@Li from Example 2, the PVDF@Li from Comparative Example 1, and the Bare Li from Comparative Example 2 were assembled into a symmetrical cell (using 1.0 M LiTFSI-DOL / DME + 0.2 M LiNO3 as the electrolyte), and the results were tested as follows. Figure 6 As shown.

[0053] from Figure 6 It can be seen that the Ni / C@Li symmetric cell at 5 mA·cm -2 / 5mAh·cm -2 Under suitable conditions, the electrode can cycle stably for over 1600 hours with stable overpotential. In contrast, PVDF@Li and Bare Li batteries exhibited significantly increased voltage polarization and even failure after only 100 hours and 300 hours, respectively. This indicates that the Ni / C artificial interface layer can effectively regulate lithium deposition behavior, endowing the electrode with excellent cycle stability.

[0054] Deposition 3mAh·cm -2 Lithium (deposition capacity of 3 mAh·cm) -2 After lithium was added, the electrode morphology was analyzed, and the results are as follows: Figure 7 As shown, (a) is a SEM image of the surface of the Ni / C@Li anode, (b) is a SEM image of the cross-section of the Ni / C@Li anode, (c) is a SEM image of the surface of the BareLi anode, and (d) is a SEM image of the cross-section of the BareLi anode.

[0055] like Figure 7 As shown in (a) and (b), the Ni / C@Li anode surface is smooth and dense, with no dendrite formation, and the deposition layer thickness is approximately 16.8 μm; while the Bare Li anode surface exhibits numerous cracks and fibrous dendrites, with a deposition layer thickness reaching 31.1 μm. Figure 7 (c) and (d)). This result visually demonstrates that the Ni / C interface layer can achieve uniform and dense lithium deposition, effectively suppressing lithium dendrite growth.

[0056] (7) Full battery cycle performance The Ni / C@Li anode from Example 2 and the Bare Li anode from Comparative Example 2 were respectively subjected to LiNi. 0.6 Co 0.2 Mn 0.2 A full cell was assembled using O2 (NCM622) as the positive electrode and 1.0 M LiPF6-EC / DEC as the electrolyte. Tests were conducted within a voltage range of 2.8–4.3 V. The results are as follows: Figure 8 As shown.

[0057] from Figure 8 It can be seen that at a 0.5C rate, the Ni / C@Li||NCM622 full cell still maintains 123.8 mAh·g after 800 cycles.-1 The specific capacity of the battery is as high as 75.9%, while the capacity of the Bare Li||NCM622 battery decreases to 30.5mAh·g. -1 The capacity retention rate was only 18.7%. This indicates that the interface layer of the present invention also has a significant performance improvement effect in the full battery system.

[0058] (8) Performance of pouch batteries To assess its practical application potential, a pouch cell was further assembled.

[0059] NCM811 pouch cell: 30μm thin lithium anode (Ni / C@thin Li) prepared using the method in Example 2 and high-loading LiNi 0.8 Co 0.1 Mn 0.1 Using O2 (NCM811) as the positive electrode, a 0.3Ah multilayer pouch cell was fabricated. Cycle performance test results are as follows: Figure 9 As shown.

[0060] from Figure 9 It can be seen that the battery at 20 mA·g -1 After cycling for more than 20 cycles at current density, the coulombic efficiency is close to 100%, demonstrating good operational stability.

[0061] (9) Lithium-sulfur pouch cell: A pouch cell assembled with a 30μm thin lithium anode (Ni / C@thin Li) and a sulfur cathode prepared using the method in Example 2. The cycle performance test results are as follows: Figure 10 As shown.

[0062] from Figure 10 It can be seen that after 120 cycles at a 0.1C rate, it still maintains 561.7 mAh·g. -1 The discharge capacity and coulombic efficiency of 94.9% indicate that this interface layer can effectively protect the lithium anode in lithium-sulfur batteries.

[0063] In summary, this invention successfully achieved a dendrite-free, highly stable lithium metal anode by constructing an artificial interface layer composed of transition metal / carbon composite particles and a fluoropolymer, utilizing the catalytic effect of the transition metal to generate a stable LiF-rich structure in situ on the lithium anode surface. System performance testing results show that this interface layer exhibits excellent electrochemical performance and practical application prospects in symmetric cells, full cells, and pouch cells, providing an effective technical path for the development of high-energy-density lithium metal batteries.

[0064] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An artificial interface layer for a lithium anode, characterized in that, This includes complexes of transition metal nanoparticles and carbon, as well as fluoropolymers.

2. The lithium anode artificial interface layer according to claim 1, characterized in that, The composite of transition metal nanoparticles and carbon has at least one of the following structures: nanocage structure, hollow structure, porous structure, solid spherical structure, and sheet structure.

3. The lithium anode artificial interface layer according to claim 1, characterized in that, The transition metal nanoparticles contain at least one of nickel, cobalt, and iron.

4. The lithium anode artificial interface layer according to claim 1, characterized in that, The fluoropolymer is polyvinylidene fluoride.

5. The lithium anode artificial interface layer according to claim 1, 2, or 4, characterized in that, The mass ratio of the transition metal nanoparticle-carbon composite to the fluoropolymer is 1:9 to 8:

2.

6. The lithium anode artificial interface layer according to claim 1, characterized in that, The thickness of the artificial interface layer of the lithium anode is 0.5~10μm.

7. The method for preparing the artificial interface layer of the lithium anode according to any one of claims 1 to 6, characterized in that, Includes the following steps: In a protective gas atmosphere, a complex of transition metal nanoparticles and carbon, a fluoropolymer, and a polar organic solvent are mixed and ultrasonicated to obtain a suspension slurry. The suspension slurry is coated onto the substrate surface and dried to obtain an artificial interface layer for the lithium anode.

8. A lithium metal anode, characterized in that, It includes a lithium metal substrate and an artificial interface layer covering at least one surface of the lithium metal substrate; The artificial interface layer is the lithium anode artificial interface layer according to any one of claims 1 to 6 or the lithium anode artificial interface layer prepared by the preparation method according to claim 7.

9. The application of the lithium anode artificial interface layer according to any one of claims 1 to 6, or the lithium anode artificial interface layer prepared by the preparation method of claim 7, or the lithium metal anode according to claim 8, in electrochemical devices.

10. The application according to claim 9, characterized in that, The electrochemical device is a battery; the battery is a lithium metal battery, a lithium-sulfur battery, or a lithium-air battery.

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