High-modulus inorganic-organic hybrid phase change protection layer for lithium metal negative electrode

Abstract

The invention discloses a high-modulus inorganic-organic hybrid phase change protection layer for a lithium metal negative electrode. The composite material is composed of a lithium-loving inorganic component and a high-modulus organic component, and an inorganic lithium-loving phase is in star-like distribution in an organic polymer matrix. The inorganic component is composed of a lithium-loving inorganic substance (preferably lithium alloy) for rapid lithium ion transmission and a lithium halide (preferably fluoride) with high electron insulation property in a composite structure, and the binding force and the mechanical strength are enhanced through in-situ interface chemical reaction with lithium metal; the organic component is composed of a thermal-response high-elasticity-modulus phase-change high-molecular polymer (preferably a thermal polymerization organic matter), the polymerization degree is increased along with temperature rise, and good flexibility and electrolyte wettability are provided for the protective layer through an in-situ polymerization phase-change reaction. The protective layer is mainly used for the negative electrode of the lithium metal battery, effectively regulates and controls the deposition and stripping uniformity of lithium ions on the surface of lithium metal, remarkably inhibits the growth of lithium metal dendrites, improves the cycling stability and coulombic efficiency of the battery, and enhances the safety of the battery.

Description

Technical Field

[0001] This invention relates to the field of lithium metal battery fabrication, specifically to a method for preparing and applying a lithium metal anode with a high-modulus inorganic-organic hybrid phase change protective layer. Background Technology

[0002] The rapid development of lithium-ion batteries has provided crucial energy support for portable electronic devices, electric vehicles, and other fields. However, with the ever-increasing demand for high-energy-density energy storage devices, the energy density of traditional lithium-ion batteries is gradually becoming insufficient to meet the higher requirements of practical applications. Lithium metal, as a battery anode material, possesses an extremely high theoretical specific capacity (3860 mAh g / g). -1 With its low redox potential (-3.04V vs. SHE), lithium metal batteries have shown great application potential in improving energy density and are widely regarded as one of the most promising new energy storage technologies for the next generation.

[0003] However, lithium metal batteries face numerous severe challenges in practical applications. Among these, the lithium metal anode undergoes side reactions with the electrolyte during cycling, not only consuming large amounts of active material and electrolyte, leading to rapid capacity decay, but also forming an uneven and unstable solid electrolyte interphase (SEI) layer on the lithium metal surface. During charge and discharge, the Li on the anode surface... + The deposition and stripping behavior of lithium metal is not entirely uniform, which leads to preferential deposition of lithium metal anodes at certain sites, resulting in irregular dendrite growth. This puts enormous pressure on the SEI (Sediment Injection Layer), and the inherent brittleness of the spontaneously generated SEI layer causes cracks or even shattering at these sites. Furthermore, the continuously growing lithium dendrites not only reduce the coulombic efficiency and cycle life of the battery, but can also puncture the separator, causing internal short circuits and posing safety hazards (such as fires and explosions), greatly limiting the commercialization of lithium metal batteries.

[0004] Therefore, surface modification of lithium metal anodes to design a more uniform SEI layer in composition and structure, enabling controllable optimization of its performance, can significantly improve the cycle performance and safety of lithium metal batteries. Currently, surface modification strategies for lithium metal anodes mainly focus on electrolyte modification and the design of artificial protective layers. Researchers have improved the SEI layer during cycling by optimizing the electrolyte solvent (Nat. Commun. 2023, 14, 868), modifying lithium salts (Adv. Funct. Mater. 2024, 34, 2416800), and designing additives (Angew. Chem. Int. Ed. 2022, 61, e202210522), thereby enhancing the compatibility between the lithium metal anode and the electrolyte and improving battery performance. However, this approach struggles to precisely control the SEI layer formation process, and the resulting protective layer exhibits heterogeneity in composition and structure, leading to regional differences in its protective effect on the lithium metal surface.

[0005] Designing artificial protective layers for lithium metal anodes has become a promising strategy for energy conservation and modification. Reported artificial protective layers are mainly categorized into inorganic material protective layers and organic polymer material protective layers. Inorganic materials (such as LiF, Li3N, and Al2O2) possess high ionic conductivity and excellent chemical stability, effectively preventing direct contact between the electrolyte and lithium metal and suppressing side reactions. However, the rigidity and brittleness of inorganic materials make them unsuitable for adapting to the significant volume deformation of lithium metal during deposition / stripping, easily leading to cracks or even peeling, thus losing their protective function. Organic polymer materials (such as PEO and PMMA) possess good flexibility and machinability, adapting well to the volume changes of lithium metal, but their ionic conductivity is typically low, and their chemical stability is relatively poor, easily swelling or dissolving in the electrolyte, making it difficult to effectively suppress lithium dendrite growth and side reactions. Therefore, there is an urgent need to develop interfacial protective layers that combine high ionic conductivity, good stability, and excellent flexibility to stabilize lithium metal anodes and achieve long cycle life and high safety performance in lithium metal batteries.

[0006] CN107221649 A discloses an electrode with an organic-inorganic composite protective layer, comprising a substrate and an organic-inorganic composite protective layer coated on the substrate, wherein the organic-inorganic composite protective layer contains LiF particles and organic molecular chains. The preparation method includes: applying a treatment solution to the substrate and reacting a fluorinated organic compound with metallic lithium within the substrate, thereby forming the organic-inorganic composite protective layer on the substrate. The electrode with this organic-inorganic composite protective layer maintains stable lithium battery structure before and after electrochemical cycling, effectively suppresses lithium dendrite growth, improves battery coulombic efficiency, and the preparation method of the composite protective layer is simple, the conditions are controllable, and it is easy to mass-produce. Applied to lithium metal secondary batteries, it improves battery cycle performance. However, the composite protective layer of this patent is only generated by a single reaction of fluorine-containing organic compounds with lithium metal to form a simple composite structure of LiF particles and organic molecular chains. Its ion transport capability and mechanical strength are limited: although the inorganic phase of LiF has electronic insulation, its ion transport capability is poor. At the same time, the dispersion of single particles lacks continuous skeleton support, and cracks are prone to occur when the volume of lithium metal changes drastically, leading to the failure of the protective layer. On the other hand, the organic molecular chains lack thermal response phase change characteristics, and cannot achieve dynamic adjustment of the degree of polymerization through temperature control, making it difficult to meet the requirements of flexibility and rigidity at different cycling stages. Summary of the Invention

[0007] This invention provides a high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes, aiming to solve the problems of poor cycle stability, disordered dendrite growth, and difficulty in ensuring safety of existing lithium metal battery anodes.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] Firstly, this invention provides a high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes. It is constructed on the surface of the lithium metal anode through an "in-situ interfacial chemical reaction-thermal-response in-situ polymerization phase change," forming a hierarchical structure of "inorganic inner layer with star-like distribution and organic outer layer with cross-linked coating." This hierarchical structure is an inorganic-organic hybrid structure, including an inorganic phase exhibiting a star-like distribution in the inner layer of the protective layer and a continuous cross-linked coating of the outer organic phase on the surface. The high-modulus inorganic-organic hybrid phase change protective layer of this invention regulates uniform lithium-ion deposition through synergistic effects, inhibits dendrite growth, and improves battery performance and safety. Existing technologies involve preparing an inorganic layer first, followed by an organic layer; this two-step preparation is detrimental to the adhesion of the protective layer and increases the complexity of the preparation process. In contrast, this invention prepares the inorganic-organic composite layer simultaneously in one step in-situ, ensuring strong adhesion.

[0010] In one embodiment of the present invention, the inorganic phase consists of a lithiophilic component and a lithium halide component. The lithiophilic component is uniformly dispersed on the lithium metal surface and distributed in a star-like pattern via an in-situ interfacial chemical reaction. The organic matrix monomers form a continuous and complete organic outer coating structure through an in-situ polymerization phase transition reaction. The lithium metal anode protective layer with an inorganic-organic hybrid hierarchical structure formed by the present invention is formed on the lithium metal surface through a process of "in-situ interfacial chemical reaction-thermal response in-situ polymerization phase transition". This includes the spontaneous in-situ interfacial chemical reaction between halides and lithium metal to generate an inorganic phase of lithiophilic and lithium halide components, which can enhance the interfacial affinity between the protective layer and the lithium metal substrate. The monomers form a continuous and complete organic polymer phase on the lithium metal surface through an in-situ polymerization phase transition reaction. The high-modulus inorganic-organic hybrid phase change protective layer of the present invention, by utilizing the ion conduction ability and electronic insulation properties of the inorganic phase, the good mechanical properties of the organic high-modulus component, and the thermal response characteristics and interface self-adaptive characteristics imparted by the phase change process, can effectively regulate the uniformity of lithium ion deposition and stripping on the lithium metal surface, while significantly suppressing the growth of lithium dendrites and improving the safety of lithium metal batteries.

[0011] As one embodiment of the present invention, the lithiophilic component in the inorganic phase is preferably selected from one of Li-Sn, Li-Sb, Li-Ag, Li-Zn, Li-Mg, Li-Al, and Li-In alloys. Sn, Sb, Ag, Zn, Mg, Al, and In in the above alloys are all typical lithiophilic metals with high binding energies to lithium, which can significantly reduce the nucleation overpotential of lithium. Simultaneously, these metals can undergo in-situ alloying reactions with lithium (e.g., Li reacts with Sn to form Li7Sn2, Li...). 22 Sn5 and other series alloy phases form a strong interface with chemical interactions, rather than a weak interface with physical contact.

[0012] As one embodiment of the present invention, the lithium-loving component in the inorganic phase has a particle size distribution in the range of 1-5 μm and is discretely distributed in the organic matrix in a star-like pattern. The average spacing between the lithium-loving sites is 20-80 μm, forming a fast lithium-ion transport channel.

[0013] In one embodiment of this invention, the lithium halide in the inorganic phase is chosen to be the most common LiF. LiF has a high band gap of 8-15 eV, making it a typical electronic insulator that can effectively block electron migration into the electrolyte, preventing electrons from reacting with lithium ions on the negative electrode surface to form lithium dendrites. Furthermore, LiF's Young's modulus is much higher than that of lithium metal and organic polymers, providing mechanical support in the lithium metal negative electrode protective layer and suppressing dendrite tip growth to a certain extent. In this invention, LiF is generated through an in-situ chemical reaction between fluoride and lithium metal, and its interface bonding with the lithium substrate is a chemical bond rather than physical adsorption, ensuring the adhesion between the protective layer and the lithium metal negative electrode.

[0014] In one embodiment of the present invention, the polymer component in the organic phase is preferably selected from one of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), poly(1,3-dioxocyclopentane) (PDOL), polyacrylonitrile (PAN), and polymethyl methacrylate (PMMA). These polymers exhibit extremely high chemical stability in ether- or carbonate-based electrolytes commonly used in lithium metal batteries. Simultaneously, these polymers can undergo cross-linking reactions through mild, simple thermal initiation curing to form a three-dimensional network structure, significantly improving the flexibility of the protective layer and ensuring its adaptability to lithium metal expansion issues. Furthermore, the decomposition and dissociation of lithium salts provide the organic polymer matrix with certain mechanical properties and lithium-ion transport capabilities.

[0015] As one embodiment of the present invention, the lithium salt in the organic phase is selected from lithium bisfluorosulfonylimide (LiFSI), lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium hexafluorophosphate (LiPF6) or lithium perchlorate (LiClO4).

[0016] In one embodiment of the present invention, the mass percentage of lithium salt in the organic phase is 10%-30%. In the present invention, the organic polymer monomer undergoes an in-situ polymerization phase transition reaction on the surface of the lithium metal anode to form a cross-linked structure with good flexibility and thermal response. The tensile strength of this artificial SEI layer reaches 5-15 MPa, and the elongation at break exceeds 95%.

[0017] In one embodiment of the present invention, the high-modulus inorganic-organic hybrid phase change protective layer for the lithium metal anode has a thickness of 5 μm to 15 μm. The outer organic phase, with continuous cross-linking on its surface, tightly coats the inorganic phase, which exhibits a star-shaped distribution. The lithium-loving component of the inorganic phase has a particle size distribution in the range of 1-5 μm and an average spacing of 20-80 μm, forming a rapid lithium-ion transport channel, which is beneficial for guiding the uniform nucleation and layered growth of lithium ions.

[0018] Secondly, the present invention provides a method for preparing a high-modulus inorganic-organic hybrid phase change protective layer; the lithium-loving inorganic-high-modulus organic composite protective layer with phase change regulation function, namely the high-modulus inorganic-organic hybrid phase change protective layer, is prepared by the steps of "precursor slurry preparation - ultrasonic atomization spraying - composite layer phase change curing".

[0019] As one embodiment of the present invention, the method includes the following steps:

[0020] S1. Preparation of precursor slurry: The inorganic dispersion, which is ultrasonically dispersed in an organic solvent, is mixed with an organic matrix solution containing lithium salt, so that the inorganic nanodots are uniformly dispersed in the mixed solution to obtain the precursor slurry.

[0021] S2, Ultrasonic atomization spraying: In a dry air atmosphere, the precursor slurry is ultrasonically sprayed onto a lithium metal sheet, and the thickness of the spray is controlled by controlling the number of coatings.

[0022] S3. Composite layer phase change curing: The coated lithium metal sheet is heated in steps to allow the solvent to evaporate and the organic monomer to polymerize in sequence, thereby preparing the high modulus inorganic-organic hybrid phase change protective layer.

[0023] In one embodiment of the present invention, in S1, the inorganic dispersion is prepared by refining the inorganic powder by ball milling and then ultrasonically dispersing it in an organic solvent with a high saturated vapor pressure.

[0024] As one embodiment of the present invention, the inorganic powder is preferably SnF4, SbF3, AgF, ZnF2, MgF2, AlF3, InF3, BN, or MoS2. The organic solvent with a high saturated vapor pressure (greater than 45 mmHg at 20°C) is preferably diethyl ether, ethylene glycol dimethyl ether, or carbon tetrachloride. The polymer monomer solution is preferably at least one of ethylene oxide, vinylidene fluoride, 1,3-dioxocyclopentane, acrylonitrile, and methyl methacrylate. The lithium salt is selected from lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), or lithium perchlorate (LiClO4); lithium bis(trifluoromethanesulfonyl)imide is preferred. The present invention emphasizes the electronic insulation (LiF) + ionic conductivity (lithium alloy) of the inorganic material + temperature-dependent phase-change organic outer layer (polymer). If other inorganic materials, such as zinc oxide, magnesium oxide, and aluminum oxide, are used, LiF cannot be generated, the electronic insulation of the protective layer cannot be guaranteed, and lithium ions may gain or lose electrons in the protective layer, forming dendrites, which does not conform to the important principle of "lithium ions deposited on the surface of lithium metal".

[0025] In one embodiment of the present invention, when refining the inorganic powder, the ball milling time is controlled to be 1 hour, the ball-to-powder ratio is 5:1-8:1, and the particle size of the inorganic material is controlled within the range of 0.5-2 μm during ball milling. When dispersing the inorganic powder, ultrasonic treatment (40-60 kHz) is performed for 1-3 hours to form an inorganic dispersion with a solid content of 2-10 wt%. When mixing the precursor slurry, stirring is performed at 300-500 rpm for 20-30 minutes to ensure uniform mixing while preventing the precursor slurry from self-polymerizing into a solid state.

[0026] In one embodiment of the present invention, in S1, the organic matrix solution is a 1-2M organic matrix solution prepared by adding lithium salt to a polymer monomer solution.

[0027] In one embodiment of the present invention, in S1, lithium salt (preferably lithium bis(trifluoromethanesulfonyl)imide) is added to a polymer monomer solution (at least one of ethylene oxide, vinylidene fluoride, 1,3-dioxolane, acrylonitrile and methyl methacrylate), and the stirring speed is 300-500 rpm for 1-2 h to form an organic matrix solution with a lithium salt concentration of 1-2 M.

[0028] As one embodiment of the present invention, 1-2 wt% thermal initiator may be added to the organic matrix solution.

[0029] In one embodiment of the present invention, in S1, the inorganic dispersion and the organic matrix solution are mixed at a volume ratio of 1:1 to 1:3. The mixture is stirred at 300-500 rpm for 20-30 minutes to ensure uniform mixing and prevent the precursor slurry from self-polymerizing into a solid state.

[0030] In one embodiment of the present invention, in S2, an ultrasonic spraying device is used in dry air with a dew point of <-30°C. The distance between the nozzle and the substrate is 10-15cm, the coating rate is 2-5mL / min, the table moving speed is 5-10mm / s, and the number of coatings is set to 1-5 times to form a uniform wet film on the lithium metal surface.

[0031] In one embodiment of the present invention, in S3, the coated lithium metal sheet is first kept at 40°C for 1-2 hours to allow the solvent to evaporate; then the temperature is raised to 60-80°C and heated for 2-6 hours to initiate the polymerization reaction of the polymer monomers, so that the organic phase forms a cross-linked network structure; thus, the high modulus inorganic-organic hybrid phase change protective layer is obtained.

[0032] In one embodiment of the present invention, in S3, the step-by-step heating steps are all carried out under argon protection.

[0033] As one embodiment of the present invention, the thickness of the prepared protective layer is controlled between 5-15 μm.

[0034] Thirdly, this invention also provides an application of a high-modulus inorganic-organic hybrid phase change protective layer in lithium metal batteries. This lithium metal anode coated with the protective layer can be directly used as an anode material in lithium metal batteries. The lithium anode protective layer prepared by this invention, when used as the anode of a lithium metal battery, can significantly reduce dendrite growth in the battery anode, lower the risk of internal short circuits and thermal runaway, and greatly improve the safety performance of lithium metal batteries under cyclic use and abuse conditions.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] 1) Synergistic suppression of lithium dendrites: The inorganic lithiophilic components are distributed in a star-like pattern, forming continuous lithium-ion channels, which is conducive to the uniform deposition of lithium ions; the large band gap of LiF improves the electronic insulation of the protective layer and effectively blocks electron conduction; the organic polymer components with thermal response form a three-dimensional network structure, which completely and tightly coats the outer layer of the lithium metal anode, and its high modulus property provides good flexibility for the protective layer. The three components work together to achieve uniform lithium deposition and effectively suppress the growth of lithium dendrites.

[0037] 2) Strong interfacial bonding: Chemical bonding at the interface is achieved through spontaneous in-situ interfacial chemical reactions and in-situ polymerization phase transition reactions. The lithium metal has high interfacial peel strength and strong bonding force with the protective layer on its surface.

[0038] 3) Process compatibility: All preparation steps are carried out at room temperature and pressure, which can be matched with existing roll-to-roll processes and is suitable for large-scale production. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below to highlight other features, objectives and advantages of the present invention:

[0040] Figure 1 This is a high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes;

[0041] Figure 2 This is a cross-sectional SEM image of a lithium metal anode with a PDSF protective layer on its surface.

[0042] Figure 3 SEM image of the artificial PDSF protective layer on the surface of the lithium metal anode;

[0043] Figure 4 A magnified SEM image of the PDSF protective layer on the surface of a lithium metal anode and its elemental distribution.

[0044] Figure 5 Infrared spectra of the organic components of the PDSF protective layer on the surface of the lithium metal anode;

[0045] Figure 6 Long-cycle constant current charge-discharge curves of symmetrical batteries assembled with PDSF-modified lithium metal anodes and unmodified lithium metal anodes;

[0046] Figure 7 A magnified view of the long-cycle constant current charge-discharge curves of a symmetrical battery assembled with a lithium metal anode modified with a PDSF protective layer and an unmodified lithium metal anode.

[0047] Figure 8 In-situ optical microscopy image of the lithium-ion deposition process on an unmodified lithium metal anode;

[0048] Figure 9 In-situ optical microscopy image of the lithium-ion deposition process in a lithium metal anode modified with a PDSF protective layer;

[0049] Figure 10 The specific capacity and coulombic efficiency of a full cell assembled with a PDSF-modified lithium metal anode, an unmodified lithium metal anode, and an NCM811 cathode at 0.5C long-cycle discharge are plotted. Detailed Implementation

[0050] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that the described embodiments are only some, not all, of the embodiments in this application. Those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0051] Example 1

[0052] A high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes, wherein the inorganic and organic components of the composite protective layer are constructed in situ on the lithium metal anode through a phase change process to form a hierarchical structure of "inorganic inner layer star-shaped distribution - organic outer layer cross-linking coating". Figure 1 This is to leverage a synergistic mechanism. The inorganic phase is prepared using SbF3, and the organic phase is prepared using DOL. The specific preparation process is as follows:

[0053] Precursor slurry preparation: SbF3 inorganic powder was refined by ball milling at a ball-to-powder ratio of 5:1 and stirred continuously at 800 rpm for 20 min to obtain powder with a particle size range of 0.5-2 μm. This powder was then dispersed in ethylene glycol dimethyl ether and sonicated for 2 h to form an inorganic dispersion with a solid content of 2 wt%. LiTFSI was added to a DOL solution and stirred at 500 rpm for 2 h to prepare a 1 M organic matrix solution. The inorganic dispersion and organic matrix solution were mixed at a volume ratio of 1:1 and stirred at 300 rpm for 20 min to uniformly disperse the inorganic nanoparticles in the solution, thus obtaining the precursor slurry.

[0054] Ultrasonic atomization spraying: In dry air with a dew point < -30℃, a precursor slurry is coated onto a lithium metal sheet using an ultrasonic spraying process. The distance between the nozzle and the substrate is adjusted to 10cm, the coating rate is 2mL / min, the stage movement speed is 5mm / s, and the coating is repeated 3 times to form a uniform wet film on the lithium metal surface. When the precursor slurry containing SbF3 comes into contact with the lithium metal sheet, SbF3 spontaneously undergoes an in-situ interfacial chemical reaction with the lithium metal (reaction formula: SbF3 + Li → Sb + LiF). The resulting Sb metal and Li metal can rapidly and spontaneously alloy at room temperature, generating in-situ star-shaped distributed Li3Sb lithium-affinity sites. Simultaneously, the obtained LiF is also uniformly distributed on the surface of the protective layer. Figure 4 ).

[0055] Composite layer phase change curing: The ultrasonically sprayed negative electrode sheet is transferred to a glove box and placed on a 40°C heating stage for 1 hour to promote the volatilization of ethylene glycol dimethyl ether (EDGDME); subsequently, the temperature is raised to 60°C and heated for 4 hours to initiate the polymerization reaction of the organic monomers, causing the organic phase to form a cross-linked network structure. The heating process thermally initiates the in-situ polymerization phase change reaction of DOLD small molecules. Figure 5 Organic monomers cross-link through covalent bonds to form a continuous and uniform three-dimensional network structure, which appears as a semi-transparent elastic film. This provides a channel for lithium-ion transport and also buffers the volume changes of the lithium metal anode through the flexibility of the organic polymer. Figure 2 As shown, the thickness of the high-modulus inorganic-organic hybrid phase change protective layer is 5μm-15μm. The outer organic phase, with continuous cross-linking on the surface, tightly coats the inorganic phase, which exhibits a star-shaped distribution. Figure 3 Among them, the inorganic lithium-affinity component has a particle size distribution in the range of 1-5 μm and an average spacing of 20-80 μm, forming a rapid transport channel for lithium ions, which is conducive to guiding the uniform nucleation and layered growth of lithium ions.

[0056] Battery assembly process: CR2025 coin cells were assembled using lithium metal with a protective coating and unmodified lithium metal as the positive and negative electrodes, respectively, with a polypropylene separator and 1M LiTFSI (DOL:DME = 1:1 + 0.1% LiNO3) as the electrolyte. 30 μL of electrolyte was added to each electrode. The assembled symmetrical cells were then placed in a constant temperature room at 25°C for 12 hours and tested on a blue electrode tester at 1 mA / cm². 2 The current density and at 1 mAh / cm 2 The capacity was subjected to constant current charge-discharge testing, and the test results are as follows: Figure 6 , 7As shown, compared to the Li / / Li symmetric cell which short-circuited after 460 hours, the modified symmetric cell can cycle stably for over 1500 hours. Lithium metal with a protective coating and unmodified lithium metal were used as negative electrodes, with a loading of 4.8 mg / cm³. 2 The NCM811 electrode was used as the positive electrode, a polypropylene separator was used, and 1M LiPF6 (EC:DMC:EMC = 1:1:1) was used as the electrolyte. 30 μL of electrolyte was added to both the positive and negative electrodes to assemble a CR2025 coin cell. The assembled cells were placed in a constant temperature room at 25°C for 12 hours, and then subjected to a constant rate charge-discharge test at 0.5C using a blue electrode tester. The test results are as follows. Figure 10 As shown, the modified battery retains >95% of its capacity after 50 cycles.

[0057] Observation of lithium-ion deposition process: Using lithium metal with a protective layer and unmodified lithium metal as positive and negative electrodes respectively, and 1M LiPF6 (EC:DMC:EMC = 1:1:1) as electrolyte, the lithium-ion deposition process and lithium dendrite growth were observed using an in-situ optical microscope. The test results are as follows: Figure 8 , 9 As shown, the modified battery exhibits more uniform lithium-ion deposition and significantly reduced dendrite growth.

[0058] Example 2

[0059] A high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes is disclosed. Both the inorganic and organic components of this composite protective layer are constructed in situ on the lithium metal anode via a phase change process, forming a hierarchical structure of "inorganic inner layer with star-like distribution and organic outer layer with cross-linking coating" to exert a synergistic effect. The inorganic phase is prepared using SbF3, and the organic phase is prepared using DOL. The specific preparation process is as follows:

[0060] Precursor slurry preparation: SbF3 inorganic powder was refined by ball milling at a ball-to-powder ratio of 5:1 and stirred continuously at 800 rpm for 20 min to obtain powder with a particle size range of 0.5-2 μm. This powder was then dispersed in ethylene glycol dimethyl ether and sonicated for 2 h to form an inorganic dispersion with a solid content of 5 wt%. LiTFSI was added to a DOL solution and stirred at 500 rpm for 2 h to prepare a 1 M organic matrix solution. The inorganic dispersion and organic matrix solution were mixed at a volume ratio of 1:1 and stirred at 300 rpm for 20 min to uniformly disperse the inorganic nanoparticles in the solution, thus obtaining the precursor slurry.

[0061] Ultrasonic atomization spraying: In dry air with a dew point < -30℃, a precursor slurry is coated onto a lithium metal sheet using an ultrasonic spraying process. The distance between the nozzle and the substrate is adjusted to 10cm, the coating rate is 2mL / min, the stage movement speed is 5mm / s, and the coating is repeated 3 times to form a uniform wet film on the lithium metal surface. When the precursor slurry containing SbF3 comes into contact with the lithium metal sheet, SbF3 spontaneously undergoes an in-situ interfacial chemical reaction with the lithium metal (reaction formula: SbF3 + Li → Sb + LiF). The resulting Sb metal and Li metal can rapidly and spontaneously alloy at room temperature, generating in-situ star-shaped distributed Li3Sb lithiophilic sites. At the same time, the resulting LiF is also uniformly distributed on the surface of the protective layer.

[0062] Composite layer phase change curing: The ultrasonically sprayed negative electrode sheet is transferred to a glove box and placed on a heating stage at 40°C for 1 hour to promote the volatilization of ethylene glycol dimethyl ether (DME). The temperature is then raised to 60°C and heated for 4 hours to initiate the polymerization reaction of the organic monomers, causing the organic phase to form a cross-linked network structure. The heating process thermally initiates the in-situ polymerization phase change reaction of DME small molecules. The organic monomers cross-link through covalent bonds to form a continuous and uniform three-dimensional network structure, which appears as a semi-transparent elastic film. This provides a channel for lithium-ion transport and also buffers the volume changes of the lithium metal negative electrode through the flexibility of the organic polymer.

[0063] Battery assembly process: CR2025 coin cells were assembled using lithium metal with a protective coating and unmodified lithium metal as the positive and negative electrodes, respectively, with a polypropylene separator and 1M LiTFSI (DOL:DME = 1:1 + 0.1% LiNO3) as the electrolyte. 30 μL of electrolyte was added to each electrode. The assembled symmetrical cells were then placed in a constant temperature room at 25°C for 12 hours and tested on a blue electrode tester at 1 mA / cm². 2 The current density and at 1 mAh / cm 2 Constant current charge-discharge tests were conducted on the modified symmetric battery to determine its capacity. Compared to the Li / / Li symmetric battery, which short-circuited after 460 hours, the modified symmetric battery could cycle stably for over 1350 hours. Lithium metal with a protective coating and unmodified lithium metal were used as negative electrodes, with a loading of 4.8 mg / cm³. 2 The NCM811 electrode was used as the positive electrode, and a polypropylene separator was used. 1M LiPF6 (EC:DMC:EMC = 1:1:1) was used as the electrolyte, with 30 μL of electrolyte added to both the positive and negative electrodes, to assemble CR2025 coin cells. After the assembled cells were placed in a constant temperature room at 25°C for 12 hours, a constant rate charge-discharge test was performed at 0.5C using a blue electrode tester. The modified battery retained >95% of its capacity after 45 cycles.

[0064] Observation of lithium-ion deposition process: Lithium metal with a protective layer and lithium metal without any modification were used as positive and negative electrodes, respectively, and 1M LiPF6 (EC:DMC:EMC=1:1:1) was used as electrolyte. The deposition process of lithium ions and the growth of lithium dendrites were observed by in-situ optical microscope. After modification, the battery deposited lithium ions more uniformly and the dendrite growth was significantly reduced.

[0065] Example 3

[0066] A high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes is disclosed. Both the inorganic and organic components of this composite protective layer are constructed in situ on the lithium metal anode via a phase change process, forming a hierarchical structure of "inorganic inner layer with star-like distribution and organic outer layer with cross-linking coating" to exert a synergistic effect. The inorganic phase is prepared using SbF3, and the organic phase is prepared using DOL. The specific preparation process is as follows:

[0067] Precursor slurry preparation: SbF3 inorganic powder was refined by ball milling at a ball-to-powder ratio of 5:1 and stirred continuously at 800 rpm for 20 min to obtain powder with a particle size range of 0.5-2 μm. This powder was then dispersed in ethylene glycol dimethyl ether and sonicated for 2 h to form an inorganic dispersion with a solid content of 10 wt%. LiTFSI was added to a DOL solution and stirred at 500 rpm for 2 h to prepare a 1 M organic matrix solution. The inorganic dispersion and organic matrix solution were mixed at a volume ratio of 1:1 and stirred at 300 rpm for 20 min to uniformly disperse the inorganic nanoparticles in the solution, thus obtaining the precursor slurry.

[0068] Ultrasonic atomization spraying: In dry air with a dew point < -30℃, a precursor slurry is coated onto a lithium metal sheet using an ultrasonic spraying process. The distance between the nozzle and the substrate is adjusted to 10cm, the coating rate is 2mL / min, the stage movement speed is 5mm / s, and the coating is repeated 3 times to form a uniform wet film on the lithium metal surface. When the precursor slurry containing SbF3 comes into contact with the lithium metal sheet, SbF3 spontaneously undergoes an in-situ interfacial chemical reaction with the lithium metal (reaction formula: SbF3 + Li → Sb + LiF). The resulting Sb metal and Li metal can rapidly and spontaneously alloy at room temperature, generating in-situ star-shaped distributed Li3Sb lithiophilic sites. At the same time, the resulting LiF is also uniformly distributed on the surface of the protective layer.

[0069] Composite layer phase change curing: The ultrasonically sprayed negative electrode sheet is transferred to a glove box and placed on a heating stage at 40°C for 1 hour to promote the volatilization of ethylene glycol dimethyl ether (DME). The temperature is then raised to 60°C and heated for 4 hours to initiate the polymerization reaction of the organic monomers, causing the organic phase to form a cross-linked network structure. The heating process thermally initiates the in-situ polymerization phase change reaction of DME small molecules. The organic monomers cross-link through covalent bonds to form a continuous and uniform three-dimensional network structure, which appears as a semi-transparent elastic film. This provides a channel for lithium-ion transport and also buffers the volume changes of the lithium metal negative electrode through the flexibility of the organic polymer.

[0070] Battery assembly process: CR2025 coin cells were assembled using lithium metal with a protective coating and unmodified lithium metal as the positive and negative electrodes, respectively, with a polypropylene separator and 1M LiTFSI (DOL:DME = 1:1 + 0.1% LiNO3) as the electrolyte. 30 μL of electrolyte was added to each electrode. The assembled symmetrical cells were then placed in a constant temperature room at 25°C for 12 hours and tested on a blue electrode tester at 1 mA / cm². 2 The current density and at 1 mAh / cm 2 Constant current charge-discharge tests were conducted on the modified symmetric battery to determine its capacity. Compared to the Li / / Li symmetric battery, which short-circuited after 460 hours, the modified symmetric battery could cycle stably for over 1000 hours. Lithium metal with a protective coating and unmodified lithium metal were used as negative electrodes, respectively, with a loading of 4.8 mg / cm³. 2 The NCM811 electrode was used as the positive electrode, and a polypropylene separator was used. 1M LiPF6 (EC:DMC:EMC = 1:1:1) was used as the electrolyte, with 30 μL of electrolyte added to both the positive and negative electrodes, to assemble CR2025 coin cells. After the assembled cells were placed in a constant temperature room at 25°C for 12 hours, a constant rate charge-discharge test was performed at 0.5C using a blue electrode tester. The modified battery retained >95% of its capacity after 45 cycles.

[0071] Observation of lithium-ion deposition process: Lithium metal with a protective layer and lithium metal without any modification were used as positive and negative electrodes, respectively, and 1M LiPF6 (EC:DMC:EMC=1:1:1) was used as electrolyte. The deposition process of lithium ions and the growth of lithium dendrites were observed by in-situ optical microscope. After modification, the battery deposited lithium ions more uniformly and the dendrite growth was significantly reduced.

[0072] Example 4

[0073] A high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes is disclosed. Both the inorganic and organic components of this composite protective layer are constructed in situ on the lithium metal anode via a phase change process, forming a hierarchical structure of "inorganic inner layer with star-like distribution and organic outer layer with cross-linking coating" to exert a synergistic effect. The inorganic phase is prepared using SbF3, and the organic phase is prepared using DOL. The specific preparation process is as follows:

[0074] Precursor slurry preparation: SbF3 inorganic powder was refined by ball milling at a ball-to-powder ratio of 5:1 and stirred continuously at 800 rpm for 20 min to obtain powder with a particle size range of 0.5-2 μm. This powder was then dispersed in ethylene glycol dimethyl ether and sonicated for 2 h to form an inorganic dispersion with a solid content of 2 wt%. LiTFSI was added to a DOL solution and stirred at 500 rpm for 2 h to prepare a 1 M organic matrix solution. The inorganic dispersion and organic matrix solution were mixed at a volume ratio of 1:1 and stirred at 300 rpm for 20 min to uniformly disperse the inorganic nanoparticles in the solution, thus obtaining the precursor slurry.

[0075] Ultrasonic atomization spraying: In dry air with a dew point < -30℃, a precursor slurry is coated onto a lithium metal sheet using an ultrasonic spraying process. The distance between the nozzle and the substrate is adjusted to 10cm, the coating rate is 2mL / min, the stage movement speed is 5mm / s, and the coating is repeated 5 times to form a uniform wet film on the lithium metal surface. When the precursor slurry containing SbF3 comes into contact with the lithium metal sheet, SbF3 spontaneously undergoes an in-situ interfacial chemical reaction with the lithium metal (reaction formula: SbF3 + Li → Sb + LiF). The resulting Sb metal and Li metal can rapidly and spontaneously alloy at room temperature, generating in-situ star-shaped distributed Li3Sb lithiophilic sites. At the same time, the resulting LiF is also uniformly distributed on the surface of the protective layer.

[0076] Composite layer phase change curing: The ultrasonically sprayed negative electrode sheet is transferred to a glove box and placed on a heating stage at 40°C for 1 hour to promote the volatilization of ethylene glycol dimethyl ether (DME). The temperature is then raised to 60°C and heated for 6 hours to initiate the polymerization reaction of the organic monomers, causing the organic phase to form a cross-linked network structure. The heating process thermally initiates the in-situ polymerization phase change reaction of DME small molecules. The organic monomers cross-link through covalent bonds to form a continuous and uniform three-dimensional network structure, which appears as a semi-transparent elastic film. This provides a channel for lithium-ion transport and also buffers the volume changes of the lithium metal negative electrode through the flexibility of the organic polymer.

[0077] Battery assembly process: CR2025 coin cells were assembled using lithium metal with a protective coating and unmodified lithium metal as the positive and negative electrodes, respectively, with a polypropylene separator and 1M LiTFSI (DOL:DME = 1:1 + 0.1% LiNO3) as the electrolyte. 30 μL of electrolyte was added to each electrode. The assembled symmetrical cells were then placed in a constant temperature room at 25°C for 12 hours and tested on a blue electrode tester at 1 mA / cm². 2 The current density and at 1 mAh / cm 2 Constant current charge-discharge tests were conducted on the modified symmetric battery to determine its capacity. Compared to the Li / / Li symmetric battery, which short-circuited after 460 hours, the modified symmetric battery could cycle stably for over 1400 hours. Lithium metal with a protective coating and unmodified lithium metal were used as negative electrodes, respectively, with a loading of 4.8 mg / cm³. 2 The NCM811 electrode was used as the positive electrode, and a polypropylene separator was used. 1M LiPF6 (EC:DMC:EMC = 1:1:1) was used as the electrolyte, with 30 μL of electrolyte added to both the positive and negative electrodes, to assemble CR2025 coin cells. After the assembled cells were placed in a constant temperature room at 25°C for 12 hours, a constant rate charge-discharge test was performed at 0.5C using a blue electrode tester. The modified battery retained >95% of its capacity after 50 cycles.

[0078] Observation of lithium-ion deposition process: Lithium metal with a protective layer and lithium metal without any modification were used as positive and negative electrodes, respectively, and 1M LiPF6 (EC:DMC:EMC=1:1:1) was used as electrolyte. The deposition process of lithium ions and the growth of lithium dendrites were observed by in-situ optical microscope. After modification, the battery deposited lithium ions more uniformly and the dendrite growth was significantly reduced.

[0079] Example 5

[0080] A high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes is disclosed. Both the inorganic and organic components of this composite protective layer are constructed in situ on the lithium metal anode via a phase change process, forming a hierarchical structure of "inorganic inner layer with star-like distribution and organic outer layer with cross-linking coating" to exert a synergistic effect. The inorganic phase is prepared using SnF4, and the organic phase is prepared using DOL. The specific preparation process is as follows:

[0081] Precursor slurry preparation: SnF4 inorganic powder was refined by ball milling at a ball-to-powder ratio of 6:1 and stirred continuously at 800 rpm for 20 min to obtain powder with a particle size range of 0.5-2 μm. This powder was then dispersed in ethylene glycol dimethyl ether and sonicated for 2 h to form an inorganic dispersion with a solid content of 2 wt%. LiTFSI was added to a DOL solution and stirred at 500 rpm for 2 h to prepare a 1 M organic matrix solution. The inorganic dispersion and organic matrix solution were mixed at a volume ratio of 1:1 and stirred at 300 rpm for 20 min to uniformly disperse the inorganic nanoparticles in the solution, thus obtaining the precursor slurry.

[0082] Ultrasonic atomization spraying: In dry air with a dew point < -30℃, a precursor slurry is coated onto a lithium metal sheet using an ultrasonic spraying process. The distance between the nozzle and the substrate is adjusted to 10cm, the coating rate is 2mL / min, the stage movement speed is 5mm / s, and the coating is repeated 5 times to form a uniform wet film on the lithium metal surface. When the precursor slurry containing SnF4 comes into contact with the lithium metal sheet, SnF4 and lithium metal spontaneously undergo an in-situ interfacial chemical reaction (reaction formula: SnF4 + Li → Sn + LiF). The resulting Sn metal and Li metal can rapidly and spontaneously alloy at room temperature, generating in-situ star-shaped distributed Li-Sn alloy lithiophilic sites. At the same time, the resulting LiF is also uniformly distributed on the surface of the protective layer.

[0083] Composite layer phase change curing: The ultrasonically sprayed negative electrode sheet is transferred to a glove box and placed on a heating stage at 40°C for 1 hour to promote the volatilization of ethylene glycol dimethyl ether (DME). The temperature is then raised to 60°C and heated for 4 hours to initiate the polymerization reaction of the organic monomers, causing the organic phase to form a cross-linked network structure. The heating process thermally initiates the in-situ polymerization phase change reaction of DME small molecules. The organic monomers cross-link through covalent bonds to form a continuous and uniform three-dimensional network structure, which appears as a semi-transparent elastic film. This provides a channel for lithium-ion transport and also buffers the volume changes of the lithium metal negative electrode through the flexibility of the organic polymer.

[0084] Battery assembly process: CR2025 coin cells were assembled using lithium metal with a protective coating and unmodified lithium metal as the positive and negative electrodes, respectively, with a polypropylene separator and 1M LiTFSI (DOL:DME = 1:1 + 0.1% LiNO3) as the electrolyte. 30 μL of electrolyte was added to each electrode. The assembled symmetrical cells were then placed in a constant temperature room at 25°C for 12 hours and tested on a blue electrode tester at 1 mA / cm². 2 The current density and at 1 mAh / cm 2Constant current charge-discharge tests were conducted on the modified symmetric battery to determine its capacity. Compared to the Li / / Li symmetric battery, which short-circuited after 460 hours, the modified symmetric battery could cycle stably for over 1000 hours. Lithium metal with a protective coating and unmodified lithium metal were used as negative electrodes, respectively, with a loading of 4.8 mg / cm³. 2 The NCM811 electrode was used as the positive electrode, and a polypropylene separator was employed. A 1M LiPF6 (EC:DMC:EMC = 1:1:1) electrolyte was used, with 30 μL of electrolyte added to both the positive and negative electrodes. A CR2025 coin cell was assembled. After the assembled cells were placed in a constant temperature room at 25°C for 12 hours, a constant rate charge-discharge test was conducted at 0.5C using a blue electrode tester. The modified battery retained >95% of its capacity after 44 cycles.

[0085] Observation of lithium-ion deposition process: Lithium metal with a protective layer and lithium metal without any modification were used as positive and negative electrodes, respectively, and 1M LiPF6 (EC:DMC:EMC=1:1:1) was used as electrolyte. The deposition process of lithium ions and the growth of lithium dendrites were observed by in-situ optical microscope. After modification, the battery deposited lithium ions more uniformly and the dendrite growth was significantly reduced.

[0086] Example 6

[0087] A high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes is disclosed. Both the inorganic and organic components of this composite protective layer are constructed in situ on the lithium metal anode via a phase change process, forming a hierarchical structure of "inorganic inner layer with star-like distribution and organic outer layer with cross-linking coating" to exert a synergistic effect. The inorganic phase is prepared using SbF3, and the organic phase is prepared using MMA. The specific preparation process is as follows:

[0088] Precursor slurry preparation: SbF3 inorganic powder was refined by ball milling at a ball-to-powder ratio of 5:1 and stirred continuously at 800 rpm for 20 min to obtain powder with a particle size ranging from 0.5 to 2 μm. This powder was then dispersed in ethylene glycol dimethyl ether and sonicated for 2 h to form an inorganic dispersion with a solid content of 2 wt%. LiTFSI was added to an MMA solution and stirred at 500 rpm for 2 h to prepare a 1 M organic matrix solution. Simultaneously, 1 wt% AIBN was added as a thermal initiator. The inorganic dispersion and organic matrix solution were mixed at a volume ratio of 1:1 and stirred at 300 rpm for 20 min to uniformly disperse the inorganic nanoparticles in the solution, thus obtaining the precursor slurry.

[0089] Ultrasonic atomization spraying: In dry air with a dew point < -30℃, a precursor slurry is coated onto a lithium metal sheet using an ultrasonic spraying process. The distance between the nozzle and the substrate is adjusted to 10cm, the coating rate is 2mL / min, the stage movement speed is 5mm / s, and the coating is repeated 3 times to form a uniform wet film on the lithium metal surface. When the precursor slurry containing SbF3 comes into contact with the lithium metal sheet, SbF3 spontaneously undergoes an in-situ interfacial chemical reaction with the lithium metal (reaction formula: SbF3 + Li → Sb + LiF). The resulting Sb metal and Li metal can rapidly and spontaneously alloy at room temperature, generating in-situ star-shaped distributed Li3Sb lithiophilic sites. At the same time, the resulting LiF is also uniformly distributed on the surface of the protective layer.

[0090] Composite layer phase change curing: The ultrasonically sprayed negative electrode sheet is transferred to a glove box and placed on a heating stage at 40°C for 1 hour to promote the volatilization of ethylene glycol dimethyl ether; then the temperature is raised to 70°C and heated for 6 hours to initiate the polymerization reaction of organic monomers, causing the organic phase to form a cross-linked network structure. During the heating process, AIBN decomposes, which can smoothly release free radicals and initiate the in-situ polymerization phase change reaction of MMA small molecules. The organic monomers cross-link through covalent bonds to form a continuous and uniform three-dimensional network structure, which appears as a semi-transparent elastic film. This provides a channel for lithium-ion transport and can also buffer the volume change of the lithium metal negative electrode through the flexibility of the organic polymer.

[0091] Battery assembly process: CR2025 coin cells were assembled using lithium metal with a protective coating and unmodified lithium metal as the positive and negative electrodes, respectively, with a polypropylene separator and 1M LiTFSI (DOL:DME = 1:1 + 0.1% LiNO3) as the electrolyte. 30 μL of electrolyte was added to each electrode. The assembled symmetrical cells were then placed in a constant temperature room at 25°C for 12 hours and tested on a blue electrode tester at 1 mA / cm². 2 The current density and at 1 mAh / cm 2 Constant current charge-discharge tests were conducted on the modified symmetric battery to determine its capacity. Compared to the Li / / Li symmetric battery, which short-circuited after 460 hours, the modified symmetric battery could cycle stably for over 1200 hours. Lithium metal with a protective coating and unmodified lithium metal were used as negative electrodes, with a loading of 4.8 mg / cm³. 2 The NCM811 electrode was used as the positive electrode, and a polypropylene separator was used. 1M LiPF6 (EC:DMC:EMC = 1:1:1) was used as the electrolyte, with 30 μL of electrolyte added to both the positive and negative electrodes, to assemble CR2025 coin cells. After the assembled cells were placed in a constant temperature room at 25°C for 12 hours, a constant rate charge-discharge test was performed at 0.5C using a blue electrode tester. The modified battery retained >95% of its capacity after 45 cycles.

[0092] Observation of lithium-ion deposition process: Lithium metal with a protective layer and lithium metal without any modification were used as positive and negative electrodes, respectively, and 1M LiPF6 (EC:DMC:EMC=1:1:1) was used as electrolyte. The deposition process of lithium ions and the growth of lithium dendrites were observed by in-situ optical microscope. After modification, the battery deposited lithium ions more uniformly and the dendrite growth was significantly reduced.

[0093] In summary, the high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes of the present invention comprises a lithiophilic inorganic component and a high-modulus organic component, with the inorganic lithiophilic phase exhibiting a star-shaped distribution within the organic polymer matrix. The inorganic component is composed of a lithiophilic inorganic component (preferably a lithium alloy) with rapid lithium-ion transport and a lithium halide component (preferably a fluoride) with high electronic insulation, forming a composite structure. Through in-situ interfacial chemical reaction with lithium metal, it effectively enhances the bonding force with the lithium metal anode and the mechanical strength of the protective layer. The organic component is composed of a thermally responsive, high-elasticity modulus phase change polymer (preferably a thermally polymerized organic compound). The degree of polymerization of the organic component increases with increasing temperature, providing good flexibility and electrolyte wettability to the protective layer through in-situ polymerization phase change reaction. The high-modulus inorganic-organic hybrid phase change protective layer is mainly used for lithium metal battery anodes, effectively controlling the uniformity of lithium-ion deposition and stripping on the lithium metal surface, significantly inhibiting lithium metal dendrite growth, improving battery cycle stability and coulombic efficiency, and enhancing battery safety.

[0094] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A high-modulus inorganic-organic hybrid phase change protective layer for lithium metal anodes, characterized in that, The lithium metal anode is constructed on the surface of the lithium metal anode through "in-situ interfacial chemical reaction-thermal response in-situ polymerization phase transition" by lithium-philic inorganic components and high-modulus organic components, forming a hierarchical structure of "inorganic inner layer star distribution-organic outer layer cross-linking coating".

2. The high-modulus inorganic-organic hybrid phase transition protective layer according to claim 1, characterized in that, The inorganic phase consists of a lithiophilic component and a lithium halide component; the lithiophilic component is uniformly dispersed on the lithium metal surface through in-situ interfacial chemical reaction and is distributed in a star-like pattern; the organic polymer monomers form a continuous and complete organic outer coating structure through in-situ polymerization phase transition reaction.

3. The high-modulus inorganic-organic hybrid phase transition protective layer according to claim 1, characterized in that, The lithiophilic component in the inorganic phase includes at least one of Li-Sn, Li-Sb, Li-Ag, Li-Zn, Li-Mg, Li-Al, Li-In, Li3N, and Li2S. The lithiophilic component has a particle size distribution in the range of 1-5 μm and is distributed in a star-like discrete manner in the organic matrix. The average spacing between the lithiophilic sites is 20-80 μm, forming a fast lithium ion transport channel.

4. The high-modulus inorganic-organic hybrid phase transition protective layer according to claim 1, characterized in that, The polymer component in the organic phase is selected from polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), poly(1,3-dioxocyclopentane) (PDOL), polyacrylonitrile (PAN), or polymethyl methacrylate (PMMA); the lithium salt is selected from lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), or lithium perchlorate (LiClO4); the mass percentage of the lithium salt in the organic phase is 10%-30%.

5. A method for preparing a high-modulus inorganic-organic hybrid phase change protective layer according to claim 1, characterized in that, The high-modulus inorganic-organic hybrid phase change protective layer is prepared through the steps of "precursor slurry preparation - ultrasonic atomization spraying - composite layer phase change curing".

6. The preparation method according to claim 5, characterized in that, The method includes the following steps: S1. Preparation of precursor slurry: The inorganic dispersion, which is ultrasonically dispersed in an organic solvent, is mixed with an organic matrix solution containing lithium salt, so that the inorganic nanodots are uniformly dispersed in the mixed solution to obtain the precursor slurry. S2, Ultrasonic atomization spraying: In a dry air atmosphere, the precursor slurry is ultrasonically sprayed onto a lithium metal sheet, and the thickness of the spray is controlled by controlling the number of coatings. S3, Composite layer phase change curing: The lithium metal sheet coated in S2 is subjected to a stepwise heating process to allow the solvent to evaporate and the organic monomer to polymerize in sequence, thereby preparing the high modulus inorganic-organic hybrid phase change protective layer.

7. The preparation method according to claim 6, characterized in that, In S1, the inorganic dispersion is prepared by refining the inorganic powder through ball milling and then ultrasonically dispersing it in an organic solvent with a high saturated vapor pressure; the organic matrix solution is a 1-2M organic matrix solution prepared by adding lithium salt to the polymer monomer solution.

8. The preparation method according to claim 7, characterized in that, Includes at least one of the following technical features: A1. The inorganic powder is selected from at least one of SnF4, SbF3, AgF, ZnF2, MgF2, AlF3, InF3, BN, and MoS2; A2. The organic solvent with a high saturated vapor pressure is selected from at least one of diethyl ether, ethylene glycol dimethyl ether, and carbon tetrachloride; A3. The polymer monomer is selected from at least one of ethylene oxide, vinylidene fluoride, 1,3-dioxolane, acrylonitrile and methyl methacrylate; A4. The lithium salt is selected from lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6) or lithium perchlorate (LiClO4); A5. The solid content of the inorganic dispersion is 2-10 wt%. A6. Inorganic dispersions and organic matrix solutions are mixed at a volume ratio of 1:1 to 1:

3.

9. The preparation method according to claim 6, characterized in that, In S2, in dry air with a dew point < -30℃, an ultrasonic spraying device is used, the distance between the nozzle and the substrate is 10-15cm, the coating rate is 2-5mL / min, the table moving speed is 5-10mm / s, and the number of coatings is set to 1-5 times. And / or, in S3, the coated lithium metal sheet is first kept at 40°C for 1-2 hours to allow the solvent to evaporate; then the temperature is raised to 60-80°C and heated for 2-6 hours to initiate the polymerization reaction of the polymer monomers, so that the organic phase forms a cross-linked network structure. And / or, the thickness of the prepared protective layer is controlled within 5-15 μm.

10. The use of the high-modulus inorganic-organic hybrid phase transition protective layer according to any one of claims 1-5, or the high-modulus inorganic-organic hybrid phase transition protective layer prepared by the method according to any one of claims 6-9, characterized in that, The lithium metal anode covered by the protective layer is used as an anode material in lithium metal batteries.

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