Solid-state electrolyte membrane based on bicontinuous lithium-conducting network and preparation method and application thereof

Abstract

The application provides a solid-state electrolyte membrane based on a bicontinuous lithium-conducting network and a preparation method and application thereof. The solid-state electrolyte membrane comprises a three-dimensional ceramic lithium-conducting network, which is a three-dimensional continuous porous ceramic skeleton; and a crosslinked polymer lithium-conducting network filled in the pores of the three-dimensional ceramic lithium-conducting network, the crosslinked polymer lithium-conducting network containing a lithium salt and a plasticizer; wherein the three-dimensional ceramic lithium-conducting network and the crosslinked polymer lithium-conducting network form a spatially interpenetrating structure through physical interlocking and / or chemical bonding, and the Li+ migration paths of the three-dimensional ceramic lithium-conducting network and the crosslinked polymer lithium-conducting network are continuously through in at least the thickness direction. The application provides a high-strength solid-state electrolyte membrane based on a bicontinuous lithium-conducting network, which significantly improves the mechanical and electrochemical properties through the synergistic effect of the ceramic network and the polymer network, and improves the cycle performance of lithium batteries, and is suitable for large-scale application of high-energy-density solid-state batteries.

Description

Technical Field

[0001] This invention belongs to the field of lithium metal battery technology, specifically relating to a solid electrolyte membrane based on a dual continuous lithium conduction network, its preparation method, and its application. Background Technology

[0002] With the rapid development of electric vehicles, portable electronic devices, and large-scale energy storage systems, high-energy-density battery technology has become a research hotspot in the field of energy storage. Lithium metal batteries (LMBs) are particularly popular due to the ultra-high theoretical capacity (3860 mAh / g) and lowest redox potential (-3.04 V vs. Li) of the lithium metal anode. ＋ Lithium-ion batteries (Li / Li) are considered a core technology for next-generation energy storage systems. However, the inherent defects of traditional liquid electrolytes (LEs)—including flammability, leakage, and uncontrolled lithium dendrite growth—lead to serious safety hazards in batteries, greatly limiting their commercial application. To address this issue, solid-state electrolytes (SSEs) have become an ideal alternative to liquid electrolytes due to their non-flammability, high mechanical strength, and physical suppression of lithium dendrite growth.

[0003] Solid-state electrolytes are mainly divided into inorganic solid-state electrolytes (ISEs) and polymeric solid-state electrolytes (SPEs). ISEs (such as oxide-based LLZO and sulfide-based Li6PS5Cl) possess high ionic conductivity (>1 mS / cm) and ultra-high elastic modulus (>10 GPa), effectively blocking lithium dendrite penetration. However, their rigidity leads to poor interfacial contact with the electrode, and microcracks easily form due to volume changes during cycling, exacerbating the increase in interfacial impedance. On the other hand, SPEs (such as polyethylene oxide (PEO) and polyacrylonitrile (PAN)) benefit from excellent flexibility and interfacial compatibility, promoting lithium dendrite penetration through chain segment movement. ＋ It can be transported, but its room temperature ionic conductivity is generally below 10. -4 The density is low (S / cm) and the mechanical strength is insufficient (usually in the MPa range), making it difficult to suppress the vertical growth of lithium dendrites.

[0004] To balance ion transport and mechanical properties, researchers have proposed the design concept of composite solid electrolytes (CSEs), which involves introducing inorganic fillers (such as LLZO, Al2O3, and TiO2) or constructing a porous framework to reinforce the polymer matrix. However, such composite systems with randomly dispersed fillers suffer from the following bottlenecks: 1) Filler agglomeration obstructs ion transport pathways, especially when the filler content exceeds 15 wt%, resulting in a significant decrease in conductivity; 2) Poor interfacial compatibility between the filler and the polymer easily leads to the formation of Li. ＋ Migration "dead zone"; 3) Isotropic structures cannot directionally regulate Li ＋ The flux is too high, making it difficult to achieve uniform lithium deposition.

[0005] The design strategy based on a three-dimensional continuous porous ceramic framework and polymer composite still faces the following challenges: 1) It is difficult to match the porosity of the ceramic framework with the crosslinking density of the polymer. While excessive porosity is beneficial for ion transport, it sacrifices mechanical strength; 2) Under dynamic stress (such as volume fluctuations caused by lithium deposition / stripping), a single network is difficult to adaptively adjust, leading to local stress concentration and crack propagation. Current technologies have not yet solved the trade-off effect between ion transport and mechanical strength in solid electrolytes, and lack a systematic solution for achieving long-term stable cycling of lithium batteries through electrolyte structure design. Currently, the commercial application of lithium metal batteries (LMBs) is still limited by the inherent defects of traditional electrolytes, such as the flammability of liquid electrolytes and the high interfacial impedance of solid electrolytes. Even when attempting to combine inorganic fillers with polymer matrices, existing solid electrolytes still face core problems such as the imbalance between mechanical and electrochemical performance. Excessive inorganic filler can block ion transport channels, while low filler content cannot provide sufficient mechanical support. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a solid electrolyte membrane based on a dual-continuous lithium-conducting network, its preparation method, and its applications. In this high-strength solid electrolyte based on a dual-continuous lithium-conducting network, the ceramic network provides rigid mechanical support, increasing the electrolyte's elastic modulus, while the polymer network achieves high ionic conductivity at room temperature through the synergistic effect of plasticizers and lithium salts. The ceramic and polymer networks, through synergistic effects, significantly improve the cycle performance of lithium batteries at both mechanical and electrochemical levels. The preparation process of this invention is compatible with roll-to-roll production and is suitable for the large-scale application of high-energy-density solid-state batteries.

[0007] In a first aspect, the present invention provides a solid electrolyte membrane based on a dual continuous lithium-conducting network, comprising a three-dimensional ceramic lithium-conducting network, wherein the three-dimensional ceramic lithium-conducting network is a three-dimensional continuous porous ceramic framework; and a cross-linked polymer lithium-conducting network filling the pores of the three-dimensional ceramic lithium-conducting network, wherein the cross-linked polymer lithium-conducting network contains lithium salt and plasticizer; wherein the three-dimensional ceramic lithium-conducting network and the cross-linked polymer lithium-conducting network form a spatially interpenetrating structure through physical interlocking and / or chemical bonding, and the Li- of the three-dimensional ceramic lithium-conducting network and the cross-linked polymer lithium-conducting network is... + The migration path is continuous at least in the thickness direction. The high-strength solid electrolyte membrane with a dual-continuous lithium-conducting network of the present invention comprises a first network structure of a three-dimensional ceramic lithium-conducting porous network and a second network structure of a cross-linked polymer lithium-conducting network. The two networks form a dual-continuous interpenetrating structure in space. The ceramic network provides rigid mechanical support, increasing the elastic modulus of the electrolyte, while the polymer network achieves high ionic conductivity at room temperature through the synergistic effect of plasticizers and lithium salts. Through the synergistic effect of the ceramic and polymer networks, the electrolyte membrane significantly improves the cycle performance of lithium batteries at both mechanical and electrochemical levels.

[0008] Preferably, the three-dimensional continuous porous ceramic framework has a three-dimensional interconnected pore structure; the porosity of the three-dimensional continuous porous ceramic framework is 30%-80%; for example, 30%, 40%, 50%, 60%, 70%, 75%, 80%, etc., preferably 55%-78%. By optimizing the porosity, the porous matrix possesses both mechanical strength and abundant pores.

[0009] Preferably, the thickness of the three-dimensional continuous porous ceramic framework is 10-300 μm; for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 200 μm, 250 μm, 300 μm, etc., and preferably 135-165 μm.

[0010] Preferably, the pore size distribution range of the three-dimensional continuous porous ceramic framework is 0.1-20 μm; for example, 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, etc., preferably 8-15 μm.

[0011] Preferably, the solid electrolyte membrane has an ionic conductivity of not less than 1.2 mS / cm at room temperature, and more preferably not less than 1.5 mS / cm; for example, 1.5 mS / cm, 1.6 mS / cm, 1.7 mS / cm, 1.8 mS / cm, 1.9 mS / cm, 2.0 mS / cm, 2.5 mS / cm, etc.; more preferably, the solid electrolyte membrane has an ionic conductivity of 1.75-1.85 mS / cm at room temperature, and more preferably 1.8 mS / cm.

[0012] In this invention, the high-strength solid electrolyte membrane based on a dual-continuous lithium-conducting network is composed of a ceramic porous network with a three-dimensional interpenetrating porous structure and a cross-linked polymer network. The ceramic porous network is constructed from a lithium-conducting ceramic material with high elastic modulus, providing stable mechanical support for the electrolyte. The porosity of the ceramic porous network ranges from 30% to 70%, the thickness ranges from 10 to 300 μm, and the pore size distribution ranges from 0.1 to 20 μm. By optimizing and controlling the parameters of the ceramic network, while ensuring a significant improvement in its elastic modulus, a uniform filling space is reserved for the cross-linked polymer network, avoiding problems such as insufficient polymer wetting or structural strength reduction caused by excessively large pores. Simultaneously, the cross-linked polymer lithium-conducting network fills the pores of the ceramic porous network, forming a spatially dual-continuous interpenetrating structure with the ceramic network. The lithium salt in the polymer network is fully dissociated under the action of the plasticizer. Through the synergistic movement of this dual-continuous lithium-conducting network and polymer segments, a continuous and efficient lithium-ion migration channel is constructed. The unique dual-continuous lithium-conducting network design of this invention allows lithium ions to be conducted intrinsically through the ceramic network while simultaneously expanding their migration path with the help of the polymer network. The interaction between these two networks significantly improves the ionic conductivity of the solid electrolyte membrane, reaching 1.2 × 10⁻⁶ at room temperature. -3 The S / cm ratio is above 1.5. Furthermore, the ceramic network and polymer network are tightly bonded together through chemical bonding or physical interlocking, which reduces the interfacial impedance between the two phases, effectively suppresses the growth of lithium dendrites, and ensures the structural stability and electrochemical performance of the solid electrolyte membrane during battery cycling.

[0013] According to some embodiments of the present invention, the porosity of the ceramic lithium-conducting network is controlled in the range of 30%-80%; the pore size distribution of the ceramic lithium-conducting network is controlled in the range of 0.1-20 μm; and the thickness of the ceramic lithium-conducting network is in the range of 10-300 μm. When the ceramic network has both a good pore structure and an elastic modulus on the order of GPa, it has excellent comprehensive performance as a solid electrolyte membrane with the first network structure.

[0014] Preferably, in the raw materials of the crosslinked polymer system, the mass ratio of lithium salt to plasticizer is 13-16:60-70; and / or, the mass ratio of polymer monomer to lithium salt is 15-25:13-16.

[0015] Further preferred, the mass ratio of polymer monomer, lithium salt and plasticizer is 18-22:13-16:63-67, and even more preferred is 19-20:14-15:64-65.

[0016] In some embodiments of the present invention, there are no restrictions on the ceramic material other than its lithium-conducting function. Similarly, there are no particular restrictions on the types of polymer materials, plasticizers, and lithium salts in the polymer crosslinking network; commonly used types in the art can be used. Furthermore, in order to optimize the various properties of the solid electrolyte membrane, the present invention has made the following optimizations to the material.

[0017] Preferably, the polymer monomer is selected from one or more of polyethylene oxide (PEO), polymethyl acrylate (PMA), polymethyl methacrylate (MMA), polyethyl acrylate (EA), polyethylene glycol acrylate (PEGMA), polyethylene glycol diacrylate (PEGDA), and pentaerythritol tetraacrylate (PETEA).

[0018] Preferably, the lithium salt is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium trifluoromethanesulfonyl)imide (LiTFSI), lithium diborate oxalate (LiBOB), lithium poly(fluorosulfonyl)imide (LiDFOB), lithium bis(oxaloate borate) borate (LiODFB), lithium bis(trifluoromethanesulfonyl)imide (LiTFMSI), lithium fluoroborate (LiBF4), lithium azide (LiN3), and lithium fluoromethylborate (LiDFBOP).

[0019] Preferably, the plasticizer is selected from one or more of propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethyl acetate (EA), diethyl terephthalate (DEP), tetrafluoroethylene (TFE), tetrahydrofuran (THF), succinic anionyl (SN), lithium fluoride, lithium chloride, and inorganic oxides, preferably including succinic anionyl (SN); the inorganic oxide includes SiO2 and / or Al2O3.

[0020] This invention addresses the shortcomings of current polymer solid electrolytes (SEEs), which exhibit poor mechanical properties but good electrochemical performance, while inorganic SEEs generally have good mechanical properties but high interfacial impedance. It also addresses the core issue of mechanical-electrochemical performance imbalance in current SEE optimization strategies—methods involving inorganic ceramics and polymer composites—where excessive inorganic filler can block ion transport channels, while low filler content fails to provide sufficient mechanical support. This invention proposes a design concept for a dual-continuous lithium-conducting network SEE membrane. Based on a three-dimensional ceramic lithium-conducting network, the SEE membrane exhibits high elastic modulus and mechanical strength; based on a cross-linked polymer network, the SEE membrane possesses high ion migration efficiency and ionic conductivity. Through a spatially interpenetrating structural design of the ceramic and polymer networks, this invention achieves synergistic optimization of mechanical strength and ion transport, thereby improving the cycle stability of lithium batteries.

[0021] Preferably, the material of the three-dimensional continuous porous ceramic framework includes one or more of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, and oxynitride solid electrolytes.

[0022] Further preferably, the oxide solid electrolyte includes one or more of LLZO, LATP, LLTO, and LLZTO; the sulfide solid electrolyte includes LGPS, Li6PS5Cl, and Li7P3S. 11 One or more of the following: the halide solid electrolyte includes one or more of Li3InCl6, Li3YCl6 and Li6PS5Br; the nitrogen oxide solid electrolyte includes LiPON.

[0023] The high-strength solid electrolyte membrane based on a dual continuous lithium-conducting network provided by this invention has high elastic modulus and mechanical strength according to the ceramic three-dimensional network; and high ion migration efficiency and room-temperature ion conductivity according to the cross-linked polymer network; in particular, through the spatial interpenetration design and synergistic effect of the ceramic network and polymer network, the mechanical strength and ion transport are synergistically optimized, thereby improving the cycle stability of lithium batteries.

[0024] Secondly, the present invention provides a method for preparing a solid electrolyte membrane based on a dual continuous lithium-ion network, comprising:

[0025] 1) Preparation of ceramic lithium-conducting porous network: Ceramic powder and pore-forming agent powder are mixed and pressed into a green body; the pore-forming agent is removed from the green body to obtain a porous green body; the porous green body is sintered under a certain atmosphere to obtain a ceramic lithium-conducting porous network (with a continuous and interconnected three-dimensional porous structure).

[0026] 2) Preparation of cross-linked polymer lithium-conducting network: Mix raw materials including polymer monomers, plasticizers, lithium salts and initiators to obtain in-situ polymerization precursor liquid; inject the in-situ polymerization precursor liquid into the ceramic lithium-conducting porous network for in-situ polymerization.

[0027] In this invention, a two-step method is used to prepare a high-strength solid electrolyte membrane with a dual continuous lithium-conducting network. First, a ceramic lithium-conducting network with a three-dimensional interpenetrating porous structure is prepared. Then, a cross-linked polymer network is prepared in situ. During the preparation of the ceramic lithium-conducting network, a solvent-based etching method and a high-temperature decomposition method are used to remove the pore-forming agent, thereby constructing the three-dimensional interpenetrating porous ceramic lithium-conducting network. The resulting ceramic lithium-conducting porous network possesses a continuous, interconnected three-dimensional pore structure. The cross-linked polymer network is then prepared using an in-situ curing method to form a solid electrolyte membrane with a dual continuous network structure.

[0028] Preferably, the ceramic powder comprises one or more of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, and oxynitride solid electrolytes; preferably, the oxide solid electrolyte comprises one or more of LLZO, LATP, LLTO, and LLZTO, with LLZO or LATP being the most preferred; the sulfide solid electrolyte comprises LGPS, Li6PS5Cl, and Li7P3S 11 One or more of the following: the halide solid electrolyte includes one or more of LiFSI, Li3InCl6, Li3YCl6, and Li6PS5Br; the nitrogen oxide solid electrolyte includes LiPON.

[0029] More preferably, the particle size of the ceramic powder is 100nm-10μm; for example, 100nm, 200nm, 300nm, 500nm, 1μm, 3μm, 5μm, 8μm, 10μm, etc.

[0030] Preferably, the pore-forming agent powder comprises one or more of polymer particles, natural biomass materials, calcium carbonate (CaCO3), magnesium carbonate (MgCO3), ammonium hydroxide (NH4OH), ammonium chloride (NH4Cl), and sodium chloride (NaCl); preferably, the polymer particles comprise one or more of polystyrene (PS), polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), polyurethane (PU), and polymethyl methacrylate; the natural biomass materials comprise one or more of cellulose, lignin, starch, wood flour, and rosin powder.

[0031] More preferably, the particle size of the pore-forming agent powder is 0.1~20μm; for example, 0.1μm, 1μm, 3μm, 5μm, 8μm, 10μm, 12μm, 15μm, 20μm, etc.

[0032] Preferably, the mass ratio of the ceramic powder to the pore-forming agent powder is 1:5-1:0.3, more preferably 2:1-3:1, such as 2:1, 7:3, 8:3, 3:1, etc.; preferably, the parameters of the pressing molding include: temperature of 25-80 ℃, pressure of 3-15 MPa, and holding time of 30-300s.

[0033] Preferably, the method for removing the pore-forming agent is stencil solvent etching and / or high-temperature decomposition; preferably, the solvent used for stencil solvent etching is selected from one or more of aqueous acidic solutions, aqueous alkaline solutions, aqueous neutral solutions, pure water, and organic solutions; the temperature of the high-temperature decomposition is 200-700 ℃, and the gas atmosphere of the high-temperature decomposition is selected from one or more of air, argon, hydrogen, nitrogen, and water vapor.

[0034] In this invention, when the template solvent etching method is selected, the solvent can be one or more of the following: aqueous acidic solutions such as sulfuric acid and hydrochloric acid; aqueous alkaline solutions such as sodium hydroxide solution and potassium hydroxide solution; aqueous neutral solutions such as sodium chloride solution and potassium chloride solution; pure water (such as deionized water); and organic solutions such as ethanol and acetone. When the high-temperature decomposition method is selected, the temperature range is 200-700 ℃; the gas atmosphere is one or a mixture of air, argon, hydrogen, nitrogen, and water vapor.

[0035] Preferably, the sintering temperature of the porous blank is 750-1300 ℃, more preferably 1000-1200 ℃; the sintering atmosphere of the porous blank is selected from one or more of air, argon, hydrogen, nitrogen and water vapor.

[0036] In this invention, depending on the selected ceramic material, the sintering temperature range of the porous green body is 750-1300 ℃, and the sintering atmosphere is one or a mixture of several of the following: air, argon, hydrogen, nitrogen and water vapor.

[0037] Preferably, the polymer monomer is selected from one or more of polyethylene oxide (PEO), polymethyl acrylate (PMA), polymethyl methacrylate (MMA), polyethyl acrylate (EA), polyethylene glycol acrylate (PEGMA), polyethylene glycol diacrylate (PEGDA), and pentaerythritol tetraacrylate (PETEA).

[0038] Preferably, the lithium salt is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bisfluorosulfonylimide (LiFSI), lithium trifluoromethanesulfonylimide (LiTFSI), lithium diborate oxalate (LiBOB), lithium polyfluorosulfonylimide (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiODFB), lithium bis(trifluoromethanesulfonyl)imide (LiTFMSI), lithium fluoroborate (LiBF4), lithium azide (LiN3), and lithium fluoromethylborate (LiDFBOP), preferably LiTFSI, LiFSI, or LiTFMSI.

[0039] Preferably, the plasticizer is selected from one or more of propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethyl acetate (EA), diethyl terephthalate (DEP), tetrafluoroethylene (TFE), tetrahydrofuran (THF), succinic anionyl nitrile (SN), lithium fluoride, lithium chloride, and inorganic oxides. Preferably, the inorganic oxides include SiO2 and / or Al2O3.

[0040] Preferably, the mass ratio of lithium salt to plasticizer is 13-16:50-70; the mass ratio of polymer monomer to lithium salt is 15-25:13-16; more preferably, the mass ratio of polymer monomer, lithium salt, and plasticizer is 18-22:13-16:63-67, and more preferably 20-21:15:64-65; for example, 20:15:65, 20:14:64, 20:14:66, 20:16:65, 20:16:64, 20:16:66, etc. This invention further optimizes the ratio of polymer monomer, lithium salt, and plasticizer in the polymer network based on the ceramic lithium-conducting porous network, significantly improving the ionic conductivity of the solid electrolyte at room temperature, while also enhancing the interaction between the polymer network and the ceramic network, thus improving the overall mechanical properties and interfacial stability.

[0041] Preferably, the initiator includes diisophorone peroxide (BPO), benzoyl peroxide (BP), or azobisisobutyronitrile (AIBN), and the initiator accounts for 0.1%-1% of the mass of the polymer monomer.

[0042] Further preferably, the raw materials for the cross-linked polymer lithium-conducting network also include optional functional additives. For example, adding fluorocarbonate (FEC) generates a LiF-rich CEI on the surface of the positive electrode particles and a LiF-rich SEI on the surface of the negative electrode, improving the stability of the battery electrolyte-electrode interface, thereby improving the battery cycle performance and safety performance.

[0043] Thirdly, the present invention provides the application of the solid electrolyte membrane based on the dual continuous lithium conduction network or the solid electrolyte membrane based on the dual continuous lithium conduction network obtained by the above preparation method in solid lithium-ion batteries, preferably in improving the cycle stability of lithium battery interfaces.

[0044] The beneficial effects of this invention are at least as follows: The dual-continuous lithium-conducting network solid electrolyte membrane provided by this invention achieves an innovative synergy of electrochemical and mechanical properties through the spatial interpenetration design of the ceramic framework and polymer network. The ceramic network provides an ultra-high elastic modulus in the GPa range and mechanically inhibits lithium dendrite penetration, significantly improving battery safety; the polymer network achieves high room-temperature ionic conductivity by optimizing the ratio of polymer monomers, lithium salts, and plasticizers. This invention provides a novel solution for the commercialization of high-energy-density, long-cycle-life lithium metal batteries that combines safety, performance, and cost advantages. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 SEM images of the interface morphology of (a) porous ceramic framework and (b) solid electrolyte membrane after in-situ polymerization provided in Embodiment 1 of the present invention.

[0047] Figure 2 (a) puncture resistance and (b) ionic conductivity as a function of temperature of the solid electrolyte membrane with dual continuous lithium-ion network provided in Embodiment 1 of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0049] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0050] Unless otherwise specified, the techniques or conditions described in the literature of this invention shall apply, or the product instructions shall be followed. Devices, instruments, reagents, etc., whose manufacturers are not specified, are all conventional products that can be purchased from legitimate channels. All experimental reagents and raw materials involved are commercially available, and all reagents are analytical grade products.

[0051] Example 1

[0052] This embodiment provides a high-strength solid electrolyte with a dual continuous lithium-conducting network, which is a three-dimensional interpenetrating structure of a ceramic lithium-conducting network and a cross-linked polymer network. The preparation steps are as follows:

[0053] LLZO powder (2 μm in diameter, ceramic network host material) and PMMA microspheres (10 μm in particle size, pore-forming agent) were mixed and ground at a mass ratio of 7:3 for 1 hour to obtain a uniformly mixed powder. The powder was placed in a 16 mm diameter hydraulic mold and held at 10 MPa for 5 minutes to obtain a tightly compacted solid green body. The solid green body was placed in a muffle furnace and heated to 450 °C at a rate of 10 °C / min in air atmosphere, and held for 2 hours to decompose the PMMA polymer particles, thereby obtaining a porous green body. The temperature was further increased to 1100 °C at a rate of 5 °C / min and held for 1 hour to obtain a three-dimensional porous ceramic framework.

[0054] PEGDA (molecular weight 650) was used as a monomer, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as a lithium salt, and succinic anhydride (SN) as a plasticizer, and they were premixed uniformly at a mass ratio of 20:15:65. 0.5% (by mass) of azobisisobutyronitrile (AIBN) was added to the above mixture, and the mixture was stirred again to obtain the polymerization precursor solution.

[0055] A precursor solution was injected between the positive and negative electrodes of the battery into a ceramic porous framework to fully wet the porous framework. The framework was then heated to 70 °C and held for 4 hours to allow the PEGDA monomer to solidify in situ, thus obtaining a solid electrolyte.

[0056] like Figures 1-2As shown, following the above preparation process, the obtained ceramic porous framework possesses lithium conductivity and a three-dimensional interconnected pore structure. The ceramic porous framework has a porosity of 75%, a pore size of 10 μm, a thickness of 150 μm, and an elastic modulus of 4.1 GPa. The solid electrolyte has a thickness of 155 μm, an ionic conductivity of 1.8 mS / cm at room temperature (25 ℃), and an electrochemical window of 4.9 V. The lithium-symmetric battery showed no short-circuit phenomenon after 1000 h of cycling. When matched with a high-nickel cathode, after 200 cycles at 0.5 C, the capacity retention rate was 85%, and the coulombic efficiency remained at 100%. When matched with a lithium iron phosphate cathode, after 500 cycles at 1 C, the capacity retention rate was 90%, and the coulombic efficiency remained at 100%.

[0057] Example 2

[0058] This embodiment provides a high-strength solid electrolyte with a dual continuous lithium-conducting network, which is a three-dimensional interpenetrating structure of a ceramic lithium-conducting network and a cross-linked polymer network. The preparation steps are as follows:

[0059] LATP nanoparticles (500 nm diameter, ceramic network host material) and NaCl powder (10 μm particle size, pore-forming agent) were mixed and ground at a mass ratio of 7.5:2.5 for 1 h to obtain a homogeneous powder. The powder was placed in a 16 mm diameter hydraulic mold and held at 8 MPa for 10 min to obtain a tightly compacted solid green body. The solid green body was immersed in deionized water for 1 h to allow the NaCl powder to fully dissolve in the water, thus obtaining a porous green body. The porous green body was placed in a muffle furnace and heated from room temperature to 850 °C at a rate of 5 °C / min, and held for 2 h to obtain a three-dimensional porous ceramic framework.

[0060] PEGMA (molecular weight 130) was used as a monomer, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as a lithium salt, and succinic anhydride (SN) as a plasticizer, and they were premixed uniformly at a mass ratio of 20:15:65. 0.5% (by mass) of azobisisobutyronitrile (AIBN) was added to the above mixture, and the mixture was stirred again to obtain the polymerization precursor solution.

[0061] A precursor solution was injected between the positive and negative electrodes of the battery into a ceramic porous framework to fully wet the porous framework. The framework was then heated to 70 °C and held for 4 h to allow the PEGDA monomer to solidify in situ, thus obtaining a solid electrolyte.

[0062] Following the above preparation process, the obtained ceramic porous framework possesses lithium conductivity and a three-dimensional interconnected pore structure. The ceramic porous framework has a porosity of 80%, a pore size of 10 μm, a thickness of 100 μm, and an elastic modulus of 3.5 GPa. The solid electrolyte has a thickness of 103 μm, an ionic conductivity of 1.5 mS / cm at room temperature (25℃), and an electrochemical window of 4.9 V. The lithium symmetric battery showed no short circuit after 800 h of cycling. When matched with a high-nickel cathode, after 200 cycles at 0.5C, the capacity retention rate was 87%, and the coulombic efficiency remained at 100%. When matched with a lithium iron phosphate cathode, after 500 cycles at 1C, the capacity retention rate was 92%, and the coulombic efficiency remained at 100%.

[0063] Example 3

[0064] The method was the same as in Example 1, except that the mass ratio of polymer monomer, lithium salt, and plasticizer was changed to 10:15:75. Following the above preparation process, the solid electrolyte exhibited an ionic conductivity of 1.9 mS / cm and an electrochemical window of 5V. When matched with a high-nickel cathode, after 200 cycles at 0.5C, the capacity retention was 85%, and the coulombic efficiency remained at 82%. When matched with a lithium iron phosphate cathode, after 400 cycles at 1C, the capacity retention was 62%, and the coulombic efficiency remained at 85%.

[0065] Example 4

[0066] The same method as in Example 1 was used, except that the lithium salt was replaced with LiFSI. Following the above preparation process, the solid electrolyte exhibited an ionic conductivity of 2.1 mS / cm and an electrochemical window of 4.6 V. When matched with a high-nickel cathode, after 200 cycles at 0.5C, the capacity retention was 88%, and the coulombic efficiency remained at 98%. When matched with a lithium iron phosphate cathode, after 500 cycles at 1C, the capacity retention was 80%, and the coulombic efficiency remained at 99%.

[0067] Example 5

[0068] The same method as in Example 1 was used, except that the mass ratio of ceramic powder to pore-forming agent powder was changed to 5:5. Following the above preparation process, the resulting porous ceramic framework had an elastic modulus of 6.2 GPa, an ionic conductivity of 1.3 mS / cm, and an electrochemical window of 5.1 V. When matched with a high-nickel cathode, after 200 cycles at 0.5C, the capacity retention was 52%, and the coulombic efficiency remained at 85%. When matched with a lithium iron phosphate cathode, after 200 cycles at 1C, the capacity retention was 60%, and the coulombic efficiency was 90%.

[0069] Example 6

[0070] The method was the same as in Example 1, except that a functional additive, fluorocarbonate (FEC), was added to the in-situ polymer precursor solution. The mass ratio of polymer monomer, lithium salt, plasticizer, and FEC was changed to 20:15:55:10. Following the above preparation process, the solid electrolyte exhibited an ionic conductivity of 1.9 mS / cm and an electrochemical window of 5.0 V. When matched with a high-nickel cathode, after 200 cycles at 0.5C, the capacity retention was 92%, and the coulombic efficiency remained at 100%. When matched with a lithium iron phosphate cathode, after 500 cycles at 1C, the capacity retention was 90%, and the coulombic efficiency remained at 99%.

[0071] Comparative Example 1

[0072] This comparative example provides a high-strength solid electrolyte composed solely of ceramic materials. The preparation steps are as follows: LLZO powder (particle size 2 μm) is dry-pressed (pressure 30 MPa, holding pressure for 20 min), and directly sintered at 1100℃ for 4 h to obtain dense ceramic sheets (porosity < 5%).

[0073] Following the above preparation process, the resulting composite electrolyte has a thickness of 100 μm, an ionic conductivity of 0.1 mS / cm at room temperature (25℃), and an electrochemical window of 5.0 V. The lithium symmetric battery exhibits a short circuit after 100 h of cycling. When matched with a high-nickel cathode, the capacity retention rate is 56% and the coulombic efficiency is 94% after 50 cycles at 0.5C. When matched with a lithium iron phosphate cathode, the capacity retention rate is 60% and the coulombic efficiency is 94% after 80 cycles at 1C.

[0074] Comparative Example 2

[0075] This comparative example provides a ceramic particle-reinforced cross-linked polymer electrolyte that does not form a continuous ceramic lithium-conducting network. The preparation steps are as follows: LATP particles (25 wt%) are mixed uniformly with PEGDA, LiTFSI, and SN (20:15:65) using strong magnetic stirring. 0.5% by weight of azobisisobutyronitrile (AIBN) is added to the above mixture, and the mixture is stirred again to obtain a polymerization precursor solution. A PE separator is sandwiched between the positive and negative electrodes of the battery, and the precursor solution is injected and allowed to stand for 1 hour to fully wet the PE separator. The mixture is then heated to 70 °C and held for 4 hours to allow the PEGDA monomers to solidify in situ, resulting in a ceramic particle-reinforced solid electrolyte.

[0076] Following the above preparation process, the resulting composite electrolyte has a thickness of 20 μm, an ionic conductivity of 0.2 mS / cm at room temperature (25℃), and an electrochemical window of 4.7 V. The lithium symmetric battery experienced a short circuit after 250 h of cycling. When matched with a high-nickel cathode, the battery failed due to a short circuit after 100 cycles at 0.5C. When matched with a lithium iron phosphate cathode, the capacity retention was 55% and the coulombic efficiency was 90% after 300 cycles at 1C.

[0077] Comparative Example 3

[0078] This comparative example provides a gel polymer electrolyte with high ionic conductivity, containing only a polymer phase and no ceramic phase. The preparation steps are as follows: PEGDA, LiTFSI, SN, and FEC (20:15:55:10) are mixed uniformly by strong magnetic stirring. 0.5% (by mass) of azobisisobutyronitrile (AIBN) is added to the above mixture, and the mixture is stirred again to obtain a polymerization precursor solution. A PE separator is sandwiched between the positive and negative electrodes of the battery, and the precursor solution is injected and allowed to stand for 1 hour to fully wet the PE separator. The mixture is then heated to 70 °C and held for 4 hours to allow the PEGDA monomer to solidify in situ, resulting in the gel polymer electrolyte.

[0079] Following the above preparation process, the resulting composite electrolyte has a thickness of 20 μm, an ionic conductivity of 2.5 mS / cm at room temperature (25℃), and an electrochemical window of 4.6 V. The lithium symmetric battery experienced a short circuit after 200 h of cycling. When matched with a high-nickel cathode, the battery failed due to a short circuit after 300 cycles at 0.5C. When matched with a lithium iron phosphate cathode, the capacity retention was 75% and the coulombic efficiency was 95% after 500 cycles at 1C.

[0080] Comparative Example 4

[0081] This comparative example provides an electrolyte with a ceramic-polymer layered structure, where the ceramic and polymer phases do not have a three-dimensional interpenetrating structure. The preparation steps are as follows: LLZO powder (particle size 300 μm) is dry-pressed (pressure 30 MPa, holding pressure for 20 min) and directly sintered at 1100℃ for 4 h to obtain a dense ceramic sheet with a thickness of 150 μm (porosity < 5%). PEGDA, LiTFSI, and SN (20:15:65) are mixed uniformly using strong magnetic stirring. 0.5% by mass of azobisisobutyronitrile (AIBN) is added to the above mixture, and the mixture is stirred again to obtain a polymerization precursor solution. The ceramic sheet is sandwiched between the positive and negative electrodes of the battery, and the precursor solution is injected at the interface between the ceramic sheet and the positive and negative electrodes. The mixture is allowed to stand for 1 h to allow the precursor solution to fully wet the ceramic sheet. The mixture is heated to 70 ℃ and held for 4 h to allow the PEGDA monomer to solidify in situ, resulting in a ceramic-polymer layered electrolyte.

[0082] Following the above preparation process, the resulting composite electrolyte has a thickness of 170 μm, an ionic conductivity of 0.1 mS / cm at room temperature (25℃), and an electrochemical window of 4.6 V. The lithium symmetric battery experienced a short circuit after 400 h of cycling. When matched with a high-nickel cathode at room temperature, the battery failed after about 50 cycles at 0.5C. When matched with a lithium iron phosphate cathode, the capacity retention was 45% and the coulombic efficiency was 60% after 50 cycles at 1C.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solid-state electrolyte membrane based on a bicontinuous lithium-conducting network, characterized in that, It includes a three-dimensional ceramic lithium-conducting network, which is a three-dimensional continuous porous ceramic framework with a three-dimensional interconnected pore structure. And a cross-linked polymer lithium-conducting network filling the pores of the three-dimensional ceramic lithium-conducting network, the cross-linked polymer lithium-conducting network containing lithium salt and plasticizer; The three-dimensional continuous porous ceramic framework has a porosity of 55%-78%, a pore size distribution range of 8-15 μm, and a thickness of 135-165 μm. The elastic modulus of the three-dimensional ceramic lithium-conducting network is on the order of GPa. The three-dimensional ceramic lithium-conducting network and the cross-linked polymer lithium-conducting network form a spatially interpenetrating structure through physical interlocking and chemical bonding. The Li-... + The migration path is continuous at least in the thickness direction, and the ionic conductivity of the solid electrolyte at room temperature is not less than 1.7 mS / cm; in the raw materials of the cross-linked polymer system, the mass ratio of lithium salt to plasticizer is 13-16:50-70; and the mass ratio of polymer monomer to lithium salt is 15-25:13-16.

2. The solid-state electrolyte film of claim 1, wherein, The polymer monomer is selected from one or more of polyethylene oxide, polymethyl acrylate, polymethyl methacrylate, polyethyl acrylate, polyethylene glycol acrylate, polyethylene glycol diacrylate, and pentaerythritol tetraacrylate. And / or, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonylimide, lithium diborate oxalate, lithium polyfluorosulfonylimide, lithium bis(trifluoromethanesulfonyl)imide, lithium fluoroborate, lithium azide, and lithium fluoromethylborate. And / or, the plasticizer is selected from one or more of propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl acetate, diethyl terephthalate, tetrafluoroethylene, tetrahydrofuran, succinic acid, lithium fluoride, lithium chloride, and inorganic oxides; the inorganic oxides include SiO2 and / or Al2O3.

3. The method of producing a solid-state electrolyte membrane based on a bicontinuous lithium-conducting network according to claim 1 or 2, characterized in that, include: 1) Preparation of ceramic lithium-conducting porous network: ceramic powder and pore-forming agent powder are mixed and pressed into a green body; the pore-forming agent is removed from the green body to obtain a porous green body; the porous green body is sintered under a certain atmosphere to obtain a ceramic lithium-conducting porous network. 2) Preparation of cross-linked polymer lithium-conducting network: Mix raw materials including polymer monomers, plasticizers, lithium salts and initiators to obtain in-situ polymerization precursor liquid; inject the in-situ polymerization precursor liquid into the ceramic lithium-conducting porous network for in-situ polymerization.

4. The production method according to claim 3, characterized by, The ceramic powder includes one or more of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, and nitrogen oxide solid electrolytes; and / or, the pore-forming agent powder includes one or more of polymer particles, natural biomass materials, calcium carbonate, magnesium carbonate, ammonium hydroxide, ammonium chloride, and sodium chloride.

5. The preparation method according to claim 4, characterized in that, The oxide solid state electrolyte includes one or more of LLZO, LATP, LLTO, and LLZTO; the sulfide solid state electrolyte includes one or more of LGPS, Li6PS5Cl, and Li7P3S 11 The halide solid state electrolyte includes one or more of LiFSI, Li3InCl6, Li3YCl6, and Li6PS5Br; the oxynitride solid state electrolyte includes LiPON; the polymeric particulate includes one or more of polystyrene, polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene, polyurethane, polymethyl methacrylate; the natural biomass material includes one or more of cellulose, lignin, starch, wood flour, and rosin powder.

6. The preparation method according to claim 5, characterized in that, The mass ratio of the ceramic powder to the pore-forming agent powder is 1:5 to 1:0.3; And / or, the parameters for the compression molding include: temperature of 25-80 ℃, pressure of 3-15 MPa, and holding time of 30-300 s.

7. The preparation method according to claim 3, characterized in that, The method for removing the pore-forming agent is stencil solvent etching and / or high-temperature decomposition; the solvent used for stencil solvent etching is selected from one or more of aqueous acidic solutions, aqueous alkaline solutions, aqueous neutral solutions, pure water, and organic solutions; the temperature of the high-temperature decomposition is 200-700 ℃, and the gas atmosphere of the high-temperature decomposition is selected from one or more of air, argon, hydrogen, nitrogen, and water vapor. And / or, the sintering temperature of the porous preform is 750-1300 ℃; the sintering atmosphere of the porous preform is selected from one or more of air, argon, hydrogen, nitrogen and water vapor.

8. The method of any one of claims 3-7, wherein, The polymer monomer is selected from one or more of polyethylene oxide, polymethyl acrylate, polymethyl methacrylate, polyethyl acrylate, polyethylene glycol acrylate, polyethylene glycol diacrylate, and pentaerythritol tetraacrylate. And / or, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonylimide, lithium diborate oxalate, lithium polyfluorosulfonylimide, lithium bis(trifluoromethanesulfonyl)imide, lithium fluoroborate, lithium azide, and lithium fluoromethylborate. And / or, the plasticizer is selected from one or more of propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl acetate, diethyl terephthalate, tetrafluoroethylene, tetrahydrofuran, succinic acid, lithium fluoride, lithium chloride and inorganic oxides, wherein the inorganic oxides include SiO2 and / or Al2O3. And / or, the mass ratio of the lithium salt to the plasticizer is 13-16:50-70; the mass ratio of the polymer monomer to the lithium salt is 15-25:13-16; And / or, the initiator includes diisophorone peroxide, benzoyl peroxide, or azobisisobutyronitrile, and the initiator accounts for 0.1%-1% of the mass of the polymer monomer.

9. The production method according to claim 8, characterized by, The mass ratio of the polymer monomer, lithium salt and plasticizer is 18-22:13-16:63-67.

10. The application of the solid electrolyte membrane based on a dual continuous lithium conduction network as described in claim 1 or 2, or the solid electrolyte membrane based on a dual continuous lithium conduction network obtained by the preparation method described in any one of claims 3-9, in a solid-state lithium-ion battery.

11. Use according to claim 10, characterized in that, Applications in improving the interfacial cycle stability of lithium batteries.

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