Surface structured interface layer of phase separation porous membranes for

Abstract

A rechargeable lithium metal battery comprises a lithium metal negative electrode, a positive electrode, an electrolyte, a diaphragm and a porous polymer film arranged on the lithium metal negative electrode and used for improving cycle performance, and the porous polymer film comprises a polar functional group so as to capture components of a solid electrolyte interface in the battery cycle process. And retaining the component in the porous structure thereof for reuse in subsequent cycles. The porous polymer film can stabilize the solid electrolyte interface structure and improve the cycle performance, so that the battery still has at least 90% of discharge capacity after 500 charge-discharge cycles at one charge-discharge rate.

Description

Cross-reference to related applications

[0001] This invention claims priority to U.S. Provisional Patent Application No. 63 / 667,834, filed July 5, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of lithium metal anode batteries. More specifically, this invention relates to a technique for improving the cycle performance of lithium metal anodes through a surface-structured interface layer. Background Technology

[0003] Lithium-ion batteries have become an indispensable technology in the field of electrochemical energy storage, and are widely used in portable electronic devices, electric vehicles, and renewable energy systems. Among many battery technologies, lithium metal batteries are considered one of the most promising anode materials for next-generation high-energy-density batteries due to their extremely high theoretical specific capacity and extremely low electrochemical potential.

[0004] However, despite these advantages, lithium metal anodes still face many inherent challenges in practical applications. Especially under high current density or rapid charge / discharge conditions, lithium metal batteries often exhibit poor cycle stability. It is worth noting that this problem becomes even more pronounced under actual areal capacity loads; for example, traditional lithium metal anodes typically begin to fail within 200 cycles, making them unsuitable for practical applications such as electric vehicles or grid-scale energy storage.

[0005] Furthermore, another major problem with lithium metal anodes is the tendency for lithium dendrites to form during repeated lithium deposition and stripping processes. These needle-like lithium dendrites can lead to uneven lithium deposition, increased interfacial impedance, and a heightened risk of internal short circuits, posing serious safety hazards. Simultaneously, the significant volume changes that occur during cycling can also damage the electrode's mechanical properties and its electrical contact with the current collector or separator. In summary, these issues cause rapid capacity decay in the battery, further shortening its cycle life.

[0006] Therefore, the present invention aims to solve the existing problems in the above-mentioned lithium metal anode batteries. Summary of the Invention

[0007] To address the aforementioned issues, this invention proposes a novel surface-structured interface scheme. By setting a three-dimensional porous film on the surface of the lithium metal anode, a uniform lithium-ion flux and homogenized lithium metal deposition are redistributed, thereby achieving uniform lithium metal deposition and stripping and enhancing the cycle performance of subsequent lithium metal batteries.

[0008] According to a first aspect of the present invention, a rechargeable lithium metal battery is provided. More specifically, the rechargeable lithium metal battery comprises: Lithium metal anode; A porous polymer membrane is disposed on the lithium metal anode to improve the cycle performance of the rechargeable lithium metal battery. The porous polymer membrane includes polar functional groups and has the following characteristics: Pores with an average diameter of 100 nanometers to 40 micrometers; Porosity is 50% to 90%; Thickness ranges from 10 micrometers to 100 micrometers; Gurley value below 30 seconds / 100 ml; and Tensile strength ranges from 0.5 MPa to 5 MPa; Diaphragm; Electrolyte; and positive electrode.

[0009] It is worth noting that the battery retains at least 90% of its discharge capacity after 500 charge-discharge cycles at 1x discharge rate.

[0010] According to one embodiment of the present invention, the porous polymer membrane for improving cycle performance captures components that detach or peel off from the solid electrolyte interface (SEI) during battery cycling and retains these components in its porous structure so that they can be reintegrated into the solid electrolyte interface during subsequent charge-discharge cycles, thereby improving the stability of the solid electrolyte interface and improving cycle performance.

[0011] Three-dimensional porous membranes can redistribute local current density and regulate lithium-ion flux to form a uniform lithium deposition beneath the membrane. By providing a space-confined and ionically conductive scaffold structure, the porous membrane can homogenize lithium deposition / stripping and suppress dendrite growth. Furthermore, the mechanical strength and structural elasticity of the three-dimensional porous membrane can accommodate volume changes in lithium metal during cycling, thereby maintaining interfacial integrity and improving the long-term performance of the battery.

[0012] According to one embodiment of the present invention, the porous polymer membrane comprises one or more of the following materials: polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-hexafluoropropylene) copolymer (PVDF-HFP), polyacrylonitrile (PAN) copolymer, polyacrylate copolymer, polystyrene copolymer, polymethyl methacrylate (PMMA) copolymer, polyvinylpyrrolidone (PVP) and its copolymers, polyetherimide (PEI) and its copolymers, polysulfone and its copolymers, polyimide (PI) and its copolymers, polyphenylene sulfide (PPS), polyethersulfone (PES) and its copolymers, polydimethylsiloxane (PDMS) and its copolymers, cellulose acetate (CA) or cellulose.

[0013] According to one embodiment of the present invention, the porous polymer membrane for improving cycle performance further includes one or more of the following additives: carbon nanotubes, vapor-grown carbon fibers, graphene, metal-organic frameworks (MOFs), and conductive polymers.

[0014] According to one embodiment of the present invention, the metal-organic framework material is any one of MOF-808, MOP-17, UiO-66, ZIF-8, ZIF-67 or HKUST-1.

[0015] According to one embodiment of the present invention, the conductive polymer material is any one of polyaniline (PANI), polypyrrole (PPY), polythiophene, or poly(3,4-ethylenedioxythiophene) (PEDOT).

[0016] According to one embodiment of the present invention, the lithium metal anode comprises a lithium metal foil laminated on a copper current collector.

[0017] According to one embodiment of the invention, the thickness of the lithium metal foil is 50 micrometers or less.

[0018] According to one embodiment of the present invention, the positive electrode comprises one or more of the following materials: lithium iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel nickel cobalt aluminum oxide, spinel-type lithium manganese oxide, or spinel-type lithium nickel manganese oxide.

[0019] According to one embodiment of the present invention, the battery further includes a separator disposed between the negative electrode and the positive electrode.

[0020] According to one embodiment of the present invention, the porous polymer membrane for improving cycle performance can promote a uniform distribution of lithium ion flux on the electrode surface and suppress the growth of lithium dendrites during multiple charge-discharge cycles.

[0021] According to one embodiment of the invention, the captured components that have detached or peeled off from the solid electrolyte interface are reintegrated into the solid electrolyte interface during subsequent lithiation / delithiation processes.

[0022] According to a second aspect of the present invention, a method for preparing the above-described lithium metal battery is provided. Specifically, the method includes the following steps: A porous polymer membrane for improving cycle performance was formed by phase separation and then dried. The porous polymer film was laminated onto a lithium metal anode; and A lithium metal battery is formed by assembling a negative electrode, a positive electrode, a separator, and an electrolyte.

[0023] According to one embodiment of the present invention, the phase separation method includes: depositing a polymer solution onto a substrate to form a polymer film, and then immersing the film in a bath containing a polymer solvent and a polymer non-solvent.

[0024] According to one embodiment of the invention, the concentration of the polymer solution ranges from 5% to 30%.

[0025] According to one embodiment of the present invention, the polymer solvent is selected from one or more of the following: acetone, chloroform, tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO).

[0026] According to one embodiment of the present invention, the polymer nonsolvent is selected from one or more of deionized water, ethanol, methanol, glycerol, butanol, hexanol, or octanol.

[0027] According to one embodiment of the invention, the thickness of the wet coating of the polymer solution on the substrate is 50 to 300 micrometers.

[0028] According to one embodiment of the present invention, the deposition temperature range for forming the porous polymer film that improves cycle performance is 25°C to 80°C.

[0029] According to one embodiment of the present invention, the substrate with the deposited polymer film is exposed at room temperature for 5 to 60 minutes before immersion in the bath liquid.

[0030] According to one embodiment of the invention, the soaking time is from 1 hour to 24 hours.

[0031] According to one embodiment of the present invention, the substrate is a glass sheet, a polyethylene terephthalate (PET) film, a polyethylene (PE) film, a polypropylene (PP) film, or a polytetrafluoroethylene (PTFE) film. Attached Figure Description

[0032] Referring to the accompanying drawings, embodiments of the present invention will be described in more detail below, wherein:

[0033] Figure 1 This demonstrates the randomness and non-uniformity of lithium-ion deposition and stripping processes in existing lithium metal anodes.

[0034] Figure 2A-2B The overall flow of a method according to an embodiment of the present invention is shown, wherein Figure 2A The process of preparing a porous polymer membrane by phase separation is shown in Figure 2, and the process of laminating the porous polymer membrane onto a lithium foil, for example, onto a current collector such as a copper current collector.

[0035] Figure 3A lithium metal anode with the porous membrane of the present invention on its surface is demonstrated to guide stable cycling behavior;

[0036] Figure 4 Experimental results show the thickness of porous membranes after phase separation and drying.

[0037] Figure 5 The results of the Greuley value test for different porous membranes are presented.

[0038] Figure 6A and Figure 6B This image shows a scanning electron microscope (SEM) image of the DW5 porous membrane, in which... Figure 6A For surface images, and Figure 6B This is the bottom image;

[0039] Figures 7A to 7E The properties of porous membranes doped with cellulose additives are demonstrated, among which... Figure 7A This is a surface scanning electron microscope image. Figure 7B This is a bottom scanning electron microscope image. Figure 7C The image is a cross-sectional scanning electron microscope image. Figure 7D The discharge capacity of lithium metal batteries using cellulose-doped modified porous membranes is shown, and Figure 7E Demonstrates its coulomb efficiency (CE);

[0040] Figures 8A to 8D The properties of porous membranes doped with carbon nanotubes (CNTs) are demonstrated, among which... Figure 8A This is a surface scanning electron microscope image. Figure 8B This is a bottom scanning electron microscope image. Figure 8C This demonstrates the discharge capacity of lithium metal batteries using carbon nanotube-modified porous membranes, and Figure 8D Demonstrates its coulomb efficiency;

[0041] Figures 9A to 9D The properties of porous membranes doped with graphene additives are demonstrated, among which... Figure 9A This is a surface scanning electron microscope image. Figure 9B This is a bottom scanning electron microscope image. Figure 9C The discharge capacity of lithium metal batteries using graphene-modified porous membranes, and Figure 9D This demonstrates its coulomb efficiency;

[0042] Figure 10A and Figure 10B The tensile test results of the porous membrane are shown, among which... Figure 10A Demonstrating the mechanical strength of different samples, and Figure 10B The mechanical strength of DW5 samples with different additives is demonstrated;

[0043] Figure 11The cycling performance of lithium metal coin cells is compared with that of pure lithium anodes and cells with anodes having DW1, DW5 and DW9 porous membranes, which are prepared from room temperature solutions.

[0044] Figure 12 The results of the cycle performance comparison of lithium metal coin cells are presented, comparing pure lithium anode with anodes with DW2, DW4, DW6 and DW8 porous membranes, wherein the DW2, DW4, DW6 and DW8 porous membranes are prepared from a solution at 60°C.

[0045] Figure 13 The image shows a cross-sectional optical image of a lithium metal battery using a pure lithium metal anode in operation, revealing the porous structure formed by lithium deposition.

[0046] Figure 14 A cross-sectional optical image of a lithium metal battery with a lithium metal anode using a DW5 porous film is shown in operation, revealing a dense and bulky lithium deposition structure.

[0047] Figure 15 Demonstrates the discharge capacity and coulombic efficiency of a pouch cell using a lithium anode with a porous membrane.

[0048] Figure 16A and Figure 16B The results of X-ray photoelectron spectroscopy (XPS) analysis of the battery samples after lithium stripping are presented, in which... Figure 16A The results are for a pure copper foil sample. Figure 16B Results were obtained using copper foil samples coated with a DW5 porous membrane;

[0049] Figure 17A and Figure 17B The O1s spectra of the battery sample after lithium stripping are shown, in which... Figure 17A The results are for a pure copper foil sample. Figure 17B Results were obtained using copper foil samples coated with a DW5 porous membrane;

[0050] Figure 18A and Figure 18B The N1s spectrum of the battery sample after lithium stripping is shown, in which... Figure 18A The results are for a pure copper foil sample. Figure 18B Results were obtained using copper foil samples coated with a DW5 porous membrane;

[0051] Figure 19A and Figure 19B The S2p spectra of the battery sample after lithium stripping are shown, in which... Figure 19A The results are for a pure copper foil sample. Figure 19B Results were obtained using copper foil samples coated with a DW5 porous film; and

[0052] Figure 20 The data results of porosimetry analysis using mercury intrusion porosimetry are presented. Detailed Implementation

[0053] In the following description, lithium metal batteries with porous polymer membranes that enhance cycle performance are listed as preferred embodiments. It will be apparent to those skilled in the art that modifications, including additions and / or substitutions, can be made without departing from the scope and spirit of the invention. Specific details may be omitted below to avoid obscuring the invention; however, this document is prepared to enable those skilled in the art to practice the techniques disclosed herein without excessive experimentation.

[0054] Lithium metal batteries exhibit various degradation mechanisms at both the positive and negative electrodes, resulting in poor cycle performance. Cycle performance refers to a battery's ability to maintain its capacity, efficiency, and structural integrity after multiple charge-discharge cycles. Poor cycle performance leads to gradual capacity decay, increased internal resistance, and reduced reliability, ultimately shortening the battery's lifespan.

[0055] The main degradation mechanisms include structural instability, the generation of side reactions, and the accumulation of mechanical stress. For the anode, one of the most serious problems is the formation of a solid electrolyte interface layer, primarily generated by the reaction between lithium metal and the electrolyte. While the initial solid electrolyte interface helps suppress the continuous decomposition of the electrolyte, its uncontrolled growth gradually consumes active lithium and electrolyte. Furthermore, due to the volume changes that occur at the lithium anode during charging and discharging, the solid electrolyte interface layer continuously cracks and regenerates, further accelerating the consumption of lithium and electrolyte, leading to capacity decay and increased internal resistance. Typically, the solid electrolyte interface layer consists of inorganic components (such as lithium carbonate and lithium fluoride) and organic compounds formed from electrolyte decomposition.

[0056] Thickening and instability of the solid electrolyte interface layer lead to increased internal resistance, reduced overall energy efficiency, and increased heat generation. This heat further exacerbates the degradation process, creating a vicious cycle. These problems, such as capacity loss, increased impedance, and poor thermal stability, collectively impair battery performance. To address these issues, current research largely focuses on developing advanced electrode materials, more stable electrolytes, protective interface coatings, and optimized battery management strategies.

[0057] In addition, another major factor affecting battery cycle performance is the unstable deposition and stripping of lithium metal, especially under charge-discharge conditions at 1x discharge rate. As shown in the prior art (see...). Figure 1Uneven lithium deposition can easily lead to the formation of dendritic structures, resulting in an uneven and non-uniform lithium metal layer. These irregular depositions are usually caused by localized current density peaks or surface defects. During repeated charge and discharge cycles, uncontrolled deposition can lead to high surface area lithium (HSAL) phenomena, while the stripping process can form isolated "dead lithium," both of which reduce coulombic efficiency and usable capacity. The accumulation of dead lithium not only wastes active lithium but also accelerates battery performance degradation. Furthermore, uncontrolled lithium dendrite growth can puncture the separator, causing internal short circuits and posing serious safety hazards.

[0058] According to a first aspect of the present invention, a lithium metal battery with significantly improved cycle performance is provided. This battery solves long-standing problems of lithium metal anodes, such as poor cycle stability, lithium dendrite formation, and mechanical degradation during charge and discharge processes, by providing a specially designed porous polymer film on the surface of the lithium metal anode.

[0059] The lithium metal battery of the present invention includes a lithium metal anode, a cathode, an electrolyte, a separator, and a porous polymer membrane disposed on the surface of the lithium metal anode to enhance cycle performance. This porous polymer significantly improves battery performance. More specifically, the membrane has a porosity of 50% to 90%, which not only effectively promotes lithium-ion transport but also provides good mechanical integrity. Notably, the membrane has pores with an average pore size of 100 nanometers to 40 micrometers and a thickness of 10 to 100 micrometers, ensuring sufficient strength to act as a mechanical barrier while also adhering to the lithium metal surface. Furthermore, the membrane has a Gare value below 30 seconds / 100 ml, indicating excellent gas permeability due to its open porous structure. The tensile strength of the membrane is between 0.5 and 5 MPa, enabling it to provide resistance to lithium dendrite formation while accommodating volume changes in the lithium metal anode during cycling.

[0060] It is worth noting that the porous polymer membrane contains polar functional groups, which enhance its affinity for lithium ions, thereby promoting a uniform distribution of lithium ions on the electrode surface. This uniformity of ion flux helps suppress the formation of lithium dendrite structures, thus improving the cycle stability of the battery.

[0061] Furthermore, this porous polymer membrane can effectively capture degradation products and debris from the solid electrolyte interface, which might otherwise lose electrochemical activity during repeated cycles. Since typical solid electrolyte interfaces are usually porous, granular, or brittle, their structure is easily damaged during the repeated expansion and contraction of the lithium metal anode, leading to the detachment of solid electrolyte interface components from the electrode surface, reducing the interface's protective effect and functional degradation. The porous polymer membrane of this invention not only physically adsorbs and retains these detached or degraded solid electrolyte interface components but also provides mechanical support, allowing these components to be reintegrated into the solid electrolyte interface during subsequent cycles. Through this mechanism, the porous polymer membrane can effectively promote the regeneration of the solid electrolyte interface, stabilize the electrode interface, and effectively mitigate irreversible lithium loss and dendrite formation, which are major challenges limiting the cycle performance of lithium metal batteries.

[0062] Through this integrated design, the lithium metal battery of the present invention can still retain at least 90% of its initial discharge capacity after at least 500 charge-discharge cycles at 1x discharge rate, meeting the practical performance indicators of high-performance rechargeable lithium batteries.

[0063] The polymer matrix used in this porous polymer membrane can be selected from one or more of the following materials: polyvinylidene fluoride (PVDF), PVDF-HFP copolymer, polyacrylonitrile (PAN) copolymer, polyacrylate copolymer, polystyrene copolymer, polymethyl methacrylate (PMMA) copolymer, polyvinylpyrrolidone (PVP) and its copolymers, polyethyleneimine (PEI) and its copolymers, polysulfones and their copolymers, polyimide (PI) and its copolymers, polyphenylene sulfide (PPS), polyethersulfone (PES) and its copolymers, polydimethylsiloxane (PDMS) and its copolymers, cellulose acetate (CA), or cellulose. These materials achieve a balance between mechanical flexibility, thermal stability, and electrochemical compatibility with the lithium metal anode and electrolyte environment.

[0064] To promote uniform lithium-ion deposition, additives can be added to the porous polymer film. These additives facilitate the formation of a more ordered porous structure during phase separation preparation. These additives can include carbon nanotubes (CNTs), vapor-grown carbon fibers, graphene, metal-organic frameworks (MOFs), and conductive polymers. MOFs such as MOF-808, MOP-17, UiO-66, ZIF-8, ZIF-67, or HKUST-1 can provide a high specific surface area framework structure for ion migration and mechanical support. Conductive polymers such as polyaniline (PANI), polypyrrole (PPY), polythiophene, or poly(3,4-ethylenedioxythiophene) (PEDOT) enhance the electrical conduction pathways in the porous network and improve interfacial stability.

[0065] Furthermore, more ordered porous structures can be prepared through various additional methods, as ordered porous polymer films are an ideal choice for high-capacity lithium metal batteries because they promote uniform lithium-ion deposition. These methods include, for example, using a template to guide the formation of the polymer structure, thereby producing an ordered structure. In some embodiments, a polymer solution can be cast onto a template surface, wherein the template can be a hard template (e.g., hard spheres) or a soft template (e.g., forming micelle structures with surfactants to guide phase separation and form an ordered porous structure).

[0066] During membrane fabrication, external conditions such as applying a temperature gradient, controlling the solvent evaporation rate, applying an electric or magnetic field, and introducing directional flow can promote the formation of an ordered pore structure. These external factors can guide the aggregation of pores, thereby forming a channel-like structure.

[0067] Phase transformation technology can also be used to generate more ordered structures by controlling the diffusion rates of solvents and non-solvents.

[0068] In addition, porous polymer membranes can be prepared using block copolymer materials. When one of the polymers in the copolymer is selectively removed, an ordered nanoporous structure membrane can be formed by self-assembly.

[0069] The lithium metal anode typically comprises a lithium foil laminated onto a copper current collector, which provides structural support and conductivity. In some embodiments, to improve energy density and reduce material usage, the thickness of the lithium foil can be less than or equal to 50 micrometers. Additionally, the cathode can be made from common lithium-ion battery cathode materials, such as lithium iron phosphate (LiFePO4), lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (NCM), lithium nickel nickel cobalt aluminum oxide (NCA), spinel-type lithium manganese oxide, or spinel-type lithium nickel manganese oxide.

[0070] A separator is placed between the negative and positive electrodes to prevent internal short circuits while also allowing ion transport. Although the separator and electrolyte configuration can follow existing standards, the porous polymer film on the lithium metal surface is the core innovation of the battery system of this invention.

[0071] During lithium deposition and stripping, this porous polymer film, which enhances cycling performance, promotes a more uniform and stable electrochemical environment at the electrode interface. The film suppresses lithium dendrite nucleation and growth by regulating local lithium-ion flux and inhibiting the formation of current hotspots. Simultaneously, the three-dimensional polar functional porous structure on the film can adapt to the volume changes of the lithium metal electrode during cycling, thereby improving interface stability and mechanical toughness.

[0072] It is noteworthy that this porous polymer membrane can capture detached or displaced solid electrolyte interface components and reintegrate them into the solid electrolyte interface structure during subsequent lithiation / delithiation cycles.

[0073] The lithium metal battery of this invention represents a significant breakthrough in the field of high-performance rechargeable battery technology by incorporating a porous polymer membrane with high porosity and polarity on the surface of the lithium metal anode. This incorporation significantly improves the battery's cycle life, safety, and energy efficiency, thereby enabling wider commercial applications of lithium metal batteries in portable electronic devices, electric vehicles, and grid energy storage systems.

[0074] According to a second aspect of the present invention, a method for preparing the above-described lithium metal battery with enhanced cycle performance is provided. The method first prepares a porous polymer membrane using phase separation technology, followed by drying to solidify its structure; after preparation, it is then laminated onto the surface of a lithium metal anode; subsequently, the anode, a cathode, a separator, and an electrolyte are assembled into a lithium metal battery.

[0075] like Figure 2A As shown, a porous polymer membrane is formed via phase separation. Figure 2B As shown, the porous polymer film is laminated onto a lithium foil (or alternatively, onto a current collector such as a copper current collector). Phase separation provides polar functional groups and ordered porous channels to guide lithium ion deposition into a uniform lithium metal deposition structure. Phase separation involves separating the polymer into two phases: a polymer-rich phase and a polymer-poor phase, thereby forming a porous structure.

[0076] In a preferred embodiment, the porous polymer membrane is prepared by a non-solvent-induced phase separation (NIPS) method. This method includes: first, preparing a polymer solution and depositing it onto a pre-selected substrate surface, the coating method including casting, blade coating, or other similar coating methods; subsequently, immersing the substrate with the deposited polymer solution into a phase separation bath, the bath solution being a mixture of a polymer solvent and a polymer non-solvent. This immersion process induces phase separation, thereby forming a porous structure on the membrane.

[0077] In this process, the mass concentration of the polymer solution is typically 5% to 30%, and its viscosity and porosity after film formation can be adjusted according to the required performance. The choice of solvent used to dissolve the polymer is crucial for effective film formation and porosity control. Suitable solvents include, but are not limited to: acetone, chloroform, tetrahydrofuran (THF), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), or dimethyl sulfoxide (DMSO). These solvents can effectively dissolve the selected polymer and have good miscibility with the selected non-solvent.

[0078] On the other hand, the non-solvent can induce phase separation during the soaking process. Suitable non-solvents include deionized water, ethanol, methanol, glycerol, butanol, hexanol, or octanol, etc. The choice of these non-solvents depends on their miscibility with the polymer but their miscibility with the solvent, which promotes the controlled deposition of the polymer matrix and forms a uniform porous structure.

[0079] Many parameters can be optimized during membrane fabrication. For example, the wet film thickness of the polymer solution deposited on the substrate surface is typically 50 to 300 micrometers; a thicker wet film results in larger pore sizes or more interconnected pores. The deposition temperature of the polymer solution is between 25°C and 80°C, which significantly affects the solvent evaporation rate and the initial membrane morphology. Before immersion in a solvent-free bath, the deposited membrane can be allowed to stand or partially dry at room temperature or a higher temperature for 5 to 60 minutes; this pre-drying time affects membrane formation and the final porous structure. Immersion time in the solvent-free bath can range from 1 hour to 24 hours to ensure adequate phase separation and complete solvent replacement.

[0080] Phase separation begins as solvent and non-solvent substitutes in the polymer membrane. As the non-solvent replaces the solvent, the polymer precipitates from the membrane, creating regions of high polymer concentration (polymer-rich phase) and low polymer concentration (polymer-poor phase). The polymer-poor phase forms a porous structure upon drying, while the polymer-rich phase solidifies to form the membrane matrix. The final porosity can be controlled by adjusting the soaking time; longer soaking times contribute to structures with higher porosity.

[0081] The substrate for polymer solution deposition plays a crucial role in the adhesion and release properties of the film. Suitable substrates can be rigid or flexible materials, such as glass sheets, polyethylene terephthalate (PET) films, polyethylene (PE) films, polypropylene (PP) films, or polytetrafluoroethylene (PTFE) films. The choice of substrate depends on the subsequent film transfer method and the required thermal or mechanical properties during lamination.

[0082] After phase separation and drying to remove all non-solvents, the resulting porous polymer film can be laminated onto a thin lithium metal foil (e.g., a lithium metal foil with a thickness of approximately 50 micrometers or less); alternatively, the lithium metal foil can also be laminated onto a current collector (e.g., copper foil). The resulting porous polymer film possesses a high surface energy on the lithium metal anode surface, promoting lithium-ion nucleation, uniformly distributing lithium-ion flux, and suppressing volume expansion during battery cycling. The resulting high porosity structure provides a surface energy greater than approximately 100 μm. 2 Specific surface area per g, such as Figure 3 As shown.

[0083] Examples of polymers used for polymer phase separation and their corresponding phase separation solvents are as follows:

[0084] 1. Polyvinylidene fluoride Compatible solvents: dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, and tetrahydrofuran

[0085] 2. Polysulfone (PSF) Compatible solvents: N-methylpyrrolidone, dimethylacetamide, dimethylformamide, tetrahydrofuran, and dichloromethane (DCM).

[0086] 3. Polyethersulfone compatible solvents: N-methylpyrrolidone, dimethylacetamide, dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide

[0087] 4. Polyacrylonitrile Compatible solvents: dimethyl sulfoxide, dimethylformamide, and dimethylacetamide

[0088] 5. Polymethyl methacrylate Compatible solvents: tetrahydrofuran, acetone, chloroform, and dichloromethane

[0089] 6. Polyimide Compatible solvents: N-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, and tetrahydrofuran

[0090] 7. Cellulose acetate compatible solvents: acetone, dimethylformamide, tetrahydrofuran, dichloromethane, and methanol (used as co-solvents)

[0091] 8. Polyvinyl alcohol (PVA) Compatible solvents: water (under heating conditions) and dimethyl sulfoxide (as a co-solvent for water).

[0092] 9. Polystyrene Compatible solvents: toluene, chloroform, dichloromethane, tetrahydrofuran, and benzene

[0093] 10. Polyethylene oxide (PEO) Compatible solvents: water, ethanol, methanol, and acetonitrile

[0094] 11. Polylactic-co-glycolic acid copolymer (PLGA) Compatible solvents: dichloromethane, chloroform, and acetone

[0095] 12. Polycaprolactone (PCL) Compatible solvents: chloroform, dichloromethane, tetrahydrofuran, and acetone

[0096] 13. Polyethyleneimine Compatible solvents: N-methylpyrrolidone, dimethyl sulfoxide, and dimethylacetamide

[0097] 14. Compatible solvents for polyethylene terephthalate: dichloroacetic acid, a mixture of phenol / 1,1,2,2-tetrachloroethane, and benzyl alcohol (under heating conditions).

[0098] Example

[0099] Example 1: Preparation of porous polymer membranes with enhanced cycling performance

[0100] Table 1 lists the composition formulations used in the examples to prepare porous polymer membranes with enhanced cycling performance. The polymer used was a vinylidene fluoride-hexafluoropropylene copolymer. The solvent used to dissolve the polymer was a mixture of 90% N,N-dimethylformamide and 10% water. Water was used as the non-solvent for polymer phase separation. The wet polymer membrane was coated using a doctor blade method. After the coated wet membrane was allowed to stand in air for 30 minutes, it was immersed in water for phase separation, and then dried in a vacuum drying oven at 60°C for 24 hours. Variable parameters in the experiments included: the mass percentage of polymer in the solution, the dissolution temperature of the polymer solution, the type of substrate used to coat the polymer membrane, and the wet coating thickness and drying conditions before phase separation. Through these experiments, the relevant parameter conditions for forming phase-separated porous membrane structures (sample numbers: DW1, DW2, DW4, DW5, DW6, DW8, and DW9) and the parameter conditions for not forming porous membranes (sample numbers: DW3, DW7, and DW10) were determined.

[0101] Table 1

[0102] Example 2: Characteristics and morphology of porous polymer membranes with enhanced cycle performance

[0103] Figure 4 The final thicknesses of various porous polymer membranes prepared using a phase separation method are shown. The thicknesses of the obtained membrane samples range from approximately 36 micrometers to 44 micrometers, with the final thickness primarily influenced by the initial wet coating thickness. The results demonstrate that adjusting the wet coating thickness can proportionally change the final membrane thickness, thus allowing for the adjustment of membrane structural properties according to specific requirements.

[0104] Figure 5This section presents the Graley values ​​of several porous polymer membrane samples. The Graley value is a standard indicator for evaluating the permeability of porous membranes, defined as the time (in seconds) required for 100 ml of air to pass through the membrane at a specific pressure. Therefore, a lower Graley value indicates better membrane permeability; conversely, a higher Graley value indicates greater resistance to gas flow. Furthermore, membrane permeability is also affected by various structural parameters, including pore size, pore size distribution, and the tortuosity of the pore network. Among the tested samples, DW1 and DW9 have the highest Graley values, indicating the worst permeability; while the DW6 membrane has the lowest Graley value, exhibiting the best permeability, indicating its good porous structure, which is beneficial for the transport of liquids and ions.

[0105] Figure 6A and Figure 6B Scanning electron microscope images of the porous polymer membrane sample DW5 are provided. Figure 6A It shows its surface morphology, while Figure 6B The bottom morphology is shown. The surface has a porous structure, resembling a dense, bulky lithium deposit. Therefore, this surface directly contacts the lithium metal foil during battery assembly, achieving better adhesion and guiding lithium deposition. In contrast, the bottom exhibits a more uniform pore size distribution and relatively smaller pore dimensions, which is beneficial for electrolyte regulation and transport. Therefore, when the bottom faces the separator, it can regulate ion flow from the positive electrode, thus supporting uniform lithium deposition. Through this dual-functional design, the larger pores on the surface can effectively accommodate and induce dense lithium growth, while the bottom facilitates uniform ion conduction on the electrolyte side. In summary, the membrane structure promotes uniform lithium deposition, inhibits lithium dendrite growth, and improves battery cycle stability.

[0106] Furthermore, the effects of various additives on the structure and morphology of the porous polymer membrane were further evaluated. In one embodiment, cellulose nanofibers were introduced as an additive into the polymer slurry at a weight percentage of 0.85%. The modified slurry was then used to prepare a porous membrane with a thickness of approximately 40 micrometers using the same film-forming method as DW5 described above. Comparative analysis showed that the addition of cellulose significantly altered the membrane structure. Figure 7A and Figure 7B The surface and bottom both exhibit small, irregularly shaped pores. This structural difference is likely due to localized interactions between the cellulose fibers and the polymer matrix during phase separation. Figure 7C The cross-sectional images further confirmed its porous structure, which showed significantly thickened pore walls, indicating that cellulose has a certain structural reinforcing effect.

[0107] When this cellulose-modified porous membrane is combined with lithium metal and paired with a lithium iron phosphate cathode for charge-discharge testing under 1C / 1C conditions, its initial capacity retention and capacity decay curves (e.g.) are observed. Figure 7D and Figure 7E As shown, the results are similar to those of a battery using a DW5 membrane, indicating that the addition of cellulose does not significantly affect its electrochemical kinetic performance, nor does it hinder lithium transport during cycling.

[0108] Another additive option was carbon nanotubes. 4.25% by weight of carbon nanotubes were added to the polymer slurry, and a porous membrane with a thickness of approximately 40 micrometers was prepared using the same film-forming method as the DW5 membrane. Structural evaluation showed that the addition of carbon nanotubes improved the surface area of ​​the porous membrane ( Figure 8A It exhibits a large number of irregularly sized pores, but its internal pore structure is basically the same as that of the DW5 porous membrane. However, its bottom ( Figure 8B The pore size of the carbon nanotubes is significantly reduced, which is presumably due to the surface tension effect of the carbon nanotubes affecting the kinetics of the phase separation process.

[0109] When carbon nanotube-modified porous membranes are combined with lithium metal and paired with lithium iron phosphate cathodes for charge-discharge testing at 1C / 1C, their initial capacity retention is comparable to that of the unmodified DW5 porous membrane. However, during continuous cycling, the carbon nanotube-modified membrane exhibits accelerated capacity decay and eventually premature failure (see [link to relevant documentation]). Figure 8C and Figure 8D The performance degradation is primarily due to the high electrical conductivity of carbon nanotubes, which causes lithium to preferentially deposit on the outer surface of the porous membrane rather than being uniformly deposited within its internal pores. This surface lithium deposition layer leads to the formation of isolated lithium clusters, commonly known as "dead lithium," which not only increases electrolyte consumption but also increases the risk of internal short circuits, thereby compromising long-term cycling stability.

[0110] Graphene was also evaluated as an additive in the preparation of porous membranes. A polymer slurry containing 1% by weight of graphene was used to form a porous membrane with a thickness of approximately 40 micrometers using the DW5 preparation method. The introduction of graphene also caused significant changes in the morphology of the porous membrane. Figure 9A and Figure 9B As shown, the surface and bottom pore structures of the graphene-containing porous membrane are generally similar to those of the DW5 porous membrane, but the pore size is more non-uniform and heterogeneous. This may be due to the surface tension effect brought about by the graphene sheets, which changes the local thermodynamic and kinetic conditions during the phase separation process.

[0111] When assembled with lithium metal and paired with a lithium iron phosphate cathode under 1C / 1C cycling conditions, the initial capacity retention of the graphene-modified porous membrane was comparable to that of the unmodified DW5 porous membrane (see...). Figure 9C and Figure 9D This similar cycling behavior may be due to the limited dispersion of graphene in the system, which prevents the formation of a continuous conductive network. As a result, the key bulk properties of the porous membrane (such as ionic conductivity, pore structure, and pore tortuosity) remain essentially unchanged compared to the DW5 porous membrane, thus failing to bring about a significant enhancement or deterioration in electrochemical performance.

[0112] like Figure 10A and Figure 10B As shown, the mechanical strength of porous polymer films is influenced by both polymer concentration and specific membrane fabrication parameters. Porous membranes prepared with higher concentrations of vinylidene fluoride-hexafluoropropylene copolymers (such as DW4 and DW8) exhibit superior mechanical integrity due to their higher polymer content and thus lower porosity. Furthermore, increasing the temperature of the polymer slurry during membrane preparation also contributes to improved membrane mechanical strength, possibly related to increased polymer chain entanglement and tighter intermolecular packing. In contrast, polyethylene-based membrane samples exhibit lower mechanical strength because the strong hydrophobicity of polyethylene facilitates pore formation during phase separation, resulting in more porous membranes with lower mechanical strength.

[0113] Among the tested samples, the DW5 porous membrane exhibited the highest porosity, which is beneficial for more uniform lithium deposition within the internal channels. However, this high porosity is also associated with relatively low mechanical strength. To address this issue, reinforcing additives can be introduced to enhance the mechanical properties of the porous membrane. Results show that this approach can improve structural strength while maintaining a high porosity structure, thereby optimizing the balance between porosity and mechanical properties.

[0114] In addition, such as Figure 20 As shown, the porosimetry results further indicate that the pore size of the DW5 porous membrane ranges from approximately 100 nanometers to 40 micrometers.

[0115] Example 3: Lithium metal battery performance with porous polymer membranes that enhance cycle performance

[0116] To evaluate the practical application effect of porous polymer membranes that enhance cycle performance in lithium metal anodes, button cells were further fabricated for comparative testing. In each button cell, lithium iron phosphate was used as the cathode material, with an areal capacity of approximately 3.1 mAh / cm². 2 This meets the industrial requirements for high-capacity positive electrodes. The separator used is a standard polyolefin-based membrane (Celgard 2400). As a control group without a porous membrane, the negative electrode uses a commercially available lithium-copper composite tape, which includes a 50μm thick lithium layer laminated on a copper current collector.

[0117] In the experimental group, the porous polymer membrane was placed directly on the lithium metal surface, with its surface having a large open pore structure facing the lithium metal and its bottom surface having a fine, uniform pore structure facing the separator. In all batteries, the electrolyte used was a 3M lithium bis(fluorosulfonyl)imide (LiFSI) solution in dimethoxyethane (DME), with 40 μL of electrolyte added to each button cell.

[0118] Figure 11 This study compares the cycling performance of lithium anodes with different porous membranes (including DW1, DW5, and DW9) with pure lithium anodes in button cells. All porous membranes were prepared from polymer solutions at room temperature. The results clearly show that the introduction of porous membranes significantly improves battery cycling performance. Unmodified pure lithium anodes exhibit capacity decay and fail after approximately 100 cycles, while lithium anodes modified with porous membranes significantly extend battery life. The DW5 sample demonstrates the best performance, retaining over 90% of its initial discharge capacity after more than 500 cycles at 1x charge-discharge rate. Notably, the DW5 sample also has the lowest Gare value among all tested samples, indicating optimal permeability, which is closely related to its excellent cycle stability. These results demonstrate that a lower Gare value—i.e., an open and effective porous structure—contributes to improved battery life.

[0119] Figure 12 The battery cycle performance test results for porous membrane samples (including DW2, DW4, DW6, and DW8) prepared from a polymer solution at 60°C are presented. The results show that, except for DW2, all other porous membrane groups outperform the pure lithium anode control group. Although the Graley values ​​of the samples are similar, samples DW6 and DW8 again exhibit excellent cycle stability, supporting stable cycling for over 500 cycles; in contrast, DW4 shows significant performance degradation after approximately 200 cycles, while DW2 shows almost no improvement in cycle performance. Therefore, even though all samples have similar Graley values, the battery performance still varies, indicating that other factors, such as the substrate, can also significantly affect performance. Notably, DW5 ( Figure 11 As shown in the figure, both DW6 and DW8 used polyethylene film as the substrate for the coating, indicating that this substrate helps improve the morphology of the porous film and its interfacial compatibility with lithium metal. These results highlight the importance of substrate selection in the preparation of porous films.

[0120] To further investigate the influence of porous membranes on lithium deposition morphology, in-situ visualization analysis was performed using the Lasertec ECCS electrochemical confocal system to detect the effect of the presence or absence of a DW5 porous membrane on lithium metal deposition.

[0121] Figure 13The image shows a comparison of a button cell battery using a pure lithium anode before and after charging. The battery structure includes a copper current collector coated with lithium foil, a separator (Celgard 2400), and an aluminum foil coated with NCM811 cathode material. During charging, lithium ions are reduced and deposited on the lithium metal surface, forming a new lithium deposition layer. The deposited lithium exhibits a porous, layered structure composed of fine particles. This structure is typically loose and unstable, easily leading to reduced coulombic efficiency, increased "dead lithium" formation, and shortened cycle life.

[0122] In comparison, Figure 14 This is the result of a similar experiment conducted after introducing a DW5 porous film between the lithium metal surface and the separator. With this configuration, the deposited lithium layer exhibits a dense and continuous morphology, similar to the structural characteristics of the underlying lithium metal. This uniform and dense deposition helps suppress lithium dendrite formation and reduce interfacial impedance, thereby improving cycle stability. Figure 14 The visualization evidence provided further confirms that the DW5 porous membrane can effectively induce more favorable lithium deposition and confirms the performance advantages observed in previous electrochemical cycling performance tests.

[0123] Furthermore, to evaluate the cycle performance of the lithium metal anode under conditions closer to real-world applications, a pouch cell was fabricated for testing. In this test, a DW5 porous membrane was composited with a 50 μm thick lithium metal foil and used as the anode in a single-layer pouch cell, and compared with a control pouch cell using a pure lithium metal anode. Both cells used an areal capacity of 3.2 mAh / cm². 2 The lithium iron phosphate cathode has a charge / discharge voltage range set at 2.5V to 3.8V, and a charge / discharge rate of 1C. For example... Figure 15 As shown, the control group (pure lithium anode) experienced a sharp decline in coulombic efficiency after approximately 300 cycles, indicating a micro-short circuit and ultimately battery failure. In contrast, the experimental group of pouch cells with the DW5 porous membrane exhibited significantly improved cycle stability, maintaining high coulombic efficiency and stability even after more than 400 cycles. These results demonstrate that the DW5 porous membrane helps induce uniform lithium deposition and suppresses the formation of structures prone to short circuits, such as lithium dendrites, thereby effectively improving battery safety and lifespan.

[0124] After the aforementioned pouch cell with a pure lithium anode failed, it was disassembled and analyzed. After drying the battery, it was observed that the electrolyte was completely depleted. Inspection of the ceramic coating of the separator revealed numerous black spots on its surface, some of which were difficult to peel off, indicating lithium dendrites penetrating the separator, leading to overcharging and reduced coulombic efficiency. Furthermore, a dense and thick lithium deposit was found on the polymer coating, with some lithium infiltrating the separator structure. Simultaneously, the lithium metal on the anode side was almost completely depleted, and the remaining lithium layer exhibited a loose structure and extremely poor adhesion, making it prone to peeling off during processing. These observations indicate that the pouch cell experienced severe lithium dendrite formation, electrolyte depletion, and lithium loss during cycling, which combined to cause battery performance degradation and eventual failure.

[0125] In contrast, disassembly and analysis of the pouch cell with a lithium anode featuring the DW5 porous membrane revealed improved structural integrity and electrochemical performance. Although the electrolyte was completely depleted after drying, only a few inconspicuous black spots were observed on the ceramic coating of the separator, and lithium deposition on the polymer coating was significantly less than in the pure lithium control group. Furthermore, the DW5 porous membrane remained intact on the anode surface, and uniform lithium deposition was visible to the naked eye, indicating that the membrane effectively guides uniform lithium deposition during cycling. After removing the separator, only a very small amount of lithium residue was found on the copper current collector surface. These results demonstrate that the porous membrane helps improve lithium utilization efficiency, reduce irreversible lithium loss, and significantly inhibit lithium dendrite formation, thereby extending battery life and enhancing safety.

[0126] Example 4: Performance of porous polymer membranes for improving cycle performance in capturing solid electrolyte interfacial components

[0127] To evaluate the ability of porous polymer membranes to capture solid electrolyte interfacial components during cycling and reuse them in subsequent cycles, thereby improving cycling performance, the following comparative experiments were conducted.

[0128] Firstly, in the full battery configuration, pure copper foil is used as the negative electrode, with an area capacity of 3.2mAh / cm². 2 The positive electrode was used, and lithium deposition and stripping were performed using 3M lithium bis(fluorosulfonyl)imide in dimethoxyethane electrolyte. The process was repeated 10 times, ending with lithium stripping. At this point, only residual solid electrolyte interface components remained on the copper foil surface, which were then analyzed by X-ray photoelectron spectroscopy (XPS). Figure 16A ( ), as a reference for comparison.

[0129] In the test group, a DW5 porous polymer film was deposited on the surface of a copper foil and subjected to the same lithium deposition / stripping procedure. After the final stripping cycle, the porous film was carefully removed, leaving the uncaptured residue on the copper foil surface, which was then subjected to X-ray photoelectron spectroscopy analysis. Figure 16B By comparing the X-ray photoelectron spectra of this sample with those of the control sample, it can be seen that the porous membrane captured and removed the solid electrolyte interface material during the cycling process.

[0130] Further, the study specifically targets the solid electrolyte interface components derived from the decomposition of lithium bis(fluorosulfonyl)imide, primarily including compounds containing elements such as fluorine, oxygen, nitrogen, and sulfur. In the F1s spectrum ( Figures 16A-16B The copper foil sample covered by the DW5 film showed a stronger signal, possibly due to the residual vinylidene fluoride-hexafluoropropylene copolymer polymer in the DW5 film; however, in O1s ( Figures 17A-17B ), N 1s( Figures 18A-18B ) and S 2p( Figures 19A-19B In the spectrum—these signals reflect the decomposition products of lithium bis(fluorosulfonyl)imide—they are abundant in the control copper foil sample, while the copper foil surface covered with a porous membrane has almost no detectable content of the above components.

[0131] The difference in results indicates that the porous membrane effectively captured and removed a large amount of solid electrolyte interface material during cycling. Therefore, these components were stripped off along with the porous membrane before X-ray photoelectron spectroscopy analysis, and no longer remained on the copper foil surface. This further verifies that the porous polymer membrane has the ability to capture solid electrolyte interface intermediates, thereby helping to improve cycling stability and reduce irreversible capacity loss.

[0132] As used herein, the terms “approximately,” “substantially,” “essentially,” and “about” are used to describe and explain a small variation. When used in conjunction with an event or situation, the term can refer to the exact occurrence of the event or situation, or approximately the occurrence of the event or situation. The term “about,” as used herein, regarding a given value or range, typically refers to a range of v10%, v5%, v1%, or v0.5% of the given value or interval, which can be understood herein as ranging from one endpoint to another or between two endpoints. Unless otherwise stated, all ranges disclosed in this disclosure include endpoints. When referring to the same numerical value or characteristic, the term may refer to a value within ±10%, ±5%, ±1%, or ±0.5% of the average of the values. Furthermore, unless explicitly stated otherwise, the term “a” as used herein should be understood to include one or more.

[0133] The above description is provided for the purpose of illustrating and describing the invention, and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to those skilled in the art.

[0134] The above embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling other skilled in the art to understand the various embodiments of the invention and the various modifications suitable for the intended particular use.

Claims

1. A rechargeable lithium metal battery, characterized in that, include: Lithium metal anode; A porous polymer membrane is disposed on the lithium metal anode to improve the cycle performance of the rechargeable lithium metal battery, wherein the porous polymer membrane includes polar functional groups and has the following characteristics: Pores with an average diameter of 100 nanometers to 40 micrometers; Porosity is 50% to 90%; Thickness ranges from 10 micrometers to 100 micrometers; A Grylls value below 30 seconds / 100 ml; and Tensile strength ranges from 0.5 MPa to 5 MPa; Diaphragm; Electrolyte; as well as positive electrode; The porous polymer membrane captures components that detach or peel off from the solid electrolyte interface during battery cycling, retains the components in its porous structure, and reintegrates the components into the solid electrolyte interface during subsequent charge-discharge cycles, thereby improving the stability of the solid electrolyte interface and improving cycle performance. The battery retains at least 90% of its discharge capacity after 500 charge-discharge cycles at a discharge rate of 1.

2. The rechargeable lithium metal battery according to claim 1, wherein the porous polymer membrane comprises one or more of the following materials: polyvinylidene fluoride, poly(vinylidene fluoride-hexafluoropropylene) copolymer, polyacrylonitrile copolymer, polyacrylate copolymer, polystyrene copolymer, polymethyl methacrylate copolymer, polyvinylpyrrolidone and its copolymers, polyetherimide and its copolymers, polysulfone and its copolymers, polyimide and its copolymers, polyphenylene sulfide, polyethersulfone and its copolymers, polydimethylsiloxane and its copolymers, cellulose acetate or cellulose.

3. The rechargeable lithium metal battery according to claim 2, wherein the porous polymer membrane further comprises one or more of the following additives: carbon nanotubes, vapor-grown carbon fibers, graphene, metal-organic framework materials, and conductive polymer materials.

4. The rechargeable lithium metal battery according to claim 3, wherein the metal-organic framework material is selected from MOF-808, MOP-17, UiO-66, ZIF-8, ZIF-67 or HKUST-1.

5. The rechargeable lithium metal battery according to claim 3, wherein the conductive polymer material is selected from polyaniline, polypyrrole, polythiophene or poly(3,4-ethylenedioxythiophene).

6. The rechargeable lithium metal battery according to claim 1, wherein the lithium metal negative electrode comprises a lithium metal foil laminated on a copper current collector.

7. The rechargeable lithium metal battery of claim 6, wherein the thickness of the lithium metal foil is 50 micrometers or less.

8. The rechargeable lithium metal battery according to claim 1, wherein the positive electrode comprises one or more of the following materials: lithium iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel nickel cobalt aluminum oxide, spinel-type lithium manganese oxide, or spinel-type lithium nickel manganese oxide.

9. The rechargeable lithium metal battery according to claim 1, wherein the rechargeable lithium metal battery further comprises a separator disposed between the negative electrode and the positive electrode.

10. The rechargeable lithium metal battery according to claim 1, wherein the porous polymer membrane promotes uniform distribution of lithium ion flux on the electrode surface and suppresses the formation of lithium dendrites during the cyclic charge-discharge process.

11. The rechargeable lithium metal battery of claim 1, wherein the components captured and detached from the solid electrolyte interface are reintegrated into the solid electrolyte interface during subsequent lithiation / delithiation processes.

12. A method for preparing a rechargeable lithium metal battery according to claim 1, characterized in that, include: A porous polymer membrane for improving cycle performance was formed by phase separation and then dried. The porous polymer film is laminated onto a lithium metal anode; as well as The lithium metal anode, cathode, separator, and electrolyte are assembled to form a lithium metal battery.

13. The method of claim 12, wherein the phase separation method comprises: A polymer solution is deposited onto a substrate to form a polymer film, which is then immersed in a bath containing both polymer solvent and polymer non-solvent.

14. The method of claim 13, wherein the concentration of the polymer solution ranges from 5% to 30%.

15. The method of claim 13, wherein the polymer solvent is selected from one or more of the following: acetone, chloroform, tetrahydrofuran, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide; and the polymer non-solvent is selected from one or more of deionized water, ethanol, methanol, glycerol, butanol, hexanol, or octanol.

16. The method of claim 13, wherein the polymer solution forms a wet coating of 50 to 300 micrometers on the substrate.

17. The method of claim 13, wherein the deposition temperature range for forming the porous polymer film is 25°C to 80°C.

18. The method of claim 13, wherein the substrate on which the polymer film is deposited is exposed at room temperature for 5 to 60 minutes before immersion in the bath solution.

19. The method of claim 12, wherein the immersion time is from 1 hour to 24 hours.

20. The method according to claim 12, wherein the substrate is a glass sheet, a polyethylene terephthalate film, a polyethylene film, a polypropylene film, or a polytetrafluoroethylene film.

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