Mof-derived lithium aluminum titanium phosphate material, method for preparing the same, composite solid electrolyte material and application thereof

Abstract

This invention provides a MOF-derived lithium aluminum titanium phosphate material, its preparation method, a composite solid electrolyte material, and its applications, relating to the technical field of solid electrolyte materials. The general chemical formula of the MOF-derived lithium aluminum titanium phosphate material is Li. 1+x Al x Ti 2‑x (PO4)3, 0.3≤x≤0.5; its preparation raw materials include titanium sources, including titanium-containing metal-organic framework materials. This invention uses titanium-containing MOFs as dual-functional materials that serve as both titanium sources and self-sacrificing templates. As a precursor, the titanium-containing MOF can simultaneously provide titanium elements and construct a multi-level porous structure in situ during the thermal conversion process. This allows the resulting LATP to not only possess micropores inherent to the crystal itself but also form abundant mesoscale channels, thereby significantly increasing the specific surface area and porosity. This provides numerous surface and near-surface migration sites for lithium ions and constructs a continuous, low-resistance high-speed lithium-ion transport network within the composite electrolyte.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte materials technology, and in particular to a MOF-derived lithium aluminum titanium phosphate material, its preparation method, composite solid electrolyte material and its application. Background Technology

[0002] The key to the development of solid-state lithium batteries lies in the design and optimization of solid-state electrolytes. LATP / polymer composite systems have attracted widespread attention due to the high ionic conductivity of LATP and the good mechanical flexibility and electrode contact of the polymer matrix. NASICON-type LATP, such as Li... 1.5 Al 0.5 Ti 1.5 (PO4)3 has advantages such as room temperature ionic conductivity of about 0.01 mS / cm, good oxidation stability, environmental friendliness, and low cost.

[0003] However, the practical application of all-solid-state batteries still faces multiple challenges. For example, ceramic electrolytes are inherently brittle and prone to cracking, and their solid-solid contact with the electrodes results in high interfacial impedance, typically requiring high-temperature or high-pressure processes to improve the contact, increasing manufacturing costs and complexity. While polymer electrolytes are easy to process and flexible, they exhibit low room-temperature ionic conductivity and a narrow electrochemical stability window. In traditional LATP / polymer composite systems, the poor interfacial compatibility between LATP particles and the polymer matrix, along with discontinuous ion transport paths, limits the improvement of overall conductivity and mechanical properties.

[0004] Current mainstream methods for synthesizing LATP include traditional solid-state reaction methods, sol-gel methods, and their improved versions. Morphology control often employs template methods (such as using polymer microspheres or biological templates), electrospinning, or freeze-drying. However, these ceramic materials are inherently brittle and hard, resulting in poor electrode contact and a tendency to undergo side reactions with lithium metal, limiting their direct application. Therefore, researchers commonly incorporate rigid inorganic fillers such as LATP into flexible polymer matrices like polyethylene oxide (PEO) to balance ion conduction and interfacial contact.

[0005] The common practice is to directly physical blend LATP particles with polymers. This method has significant limitations: when the filler content is high (usually exceeding 10 wt%), the nanoparticles are prone to agglomeration and isolation by the polymer phase, which in turn blocks ion channels and leads to a decrease in overall conductivity.

[0006] To construct continuous ion transport networks, current technologies have shifted towards pre-fabricating three-dimensional interconnected porous ceramic frameworks (such as through cryogenic casting or sacrificial template methods) and then composited with polymers. However, these composite electrolytes based on porous frameworks still face common challenges: the interfacial contact between the inorganic ceramic and organic polymer phases remains inherently weak, resulting in poor compatibility. This makes the internal ion transport pathways insufficiently interconnected, hindering stable operation at high current densities.

[0007] In summary, the existing technology has the following key problems that urgently need to be solved: 1. The contradiction between the effective amount of filler and ion channel blockage: When the amount of rigid inorganic filler (such as LATP) added is increased to improve ionic conductivity, the nanoparticles are prone to uncontrolled aggregation in the polymer matrix. These aggregates are isolated by the polymer phase, thus hindering lithium-ion transport and severely disrupting the continuity of ion channels; 2. Transport bottleneck caused by physical contact at the two-phase interface: Current strategies based on porous ceramic frameworks and polymer fillers are limited by the fact that the inorganic filler and organic substrate are only physically bonded, resulting in poor interfacial compatibility and numerous microscopic defects and contact voids. This leads to a significant increase in resistance for lithium ions crossing the two-phase interface, becoming the main source of internal resistance in the full cell; 3. Challenges in material stability and long-term cycling: Ti in contact with LATP and lithium metal anode 4+ It is easily reduced, forming a high-resistivity layer, which leads to increased polarization and continuous deterioration of cycling performance; 4. Obstacles to the practical application of complex three-dimensional skeleton fabrication processes: Although methods such as freeze drying and sacrificial templates can produce ideal porous ceramic skeletons, these processes are often cumbersome, have harsh conditions (such as ultra-low temperature and high temperature sintering), are costly, and are difficult to precisely control the uniformity and continuity of the structure, which is still far from large-scale production.

[0008] In view of this, the present invention is proposed. Summary of the Invention

[0009] One of the objectives of this invention is to provide a MOF-derived lithium aluminum titanium phosphate material to at least solve one of the technical problems existing in the prior art.

[0010] The second objective of this invention is to provide a method for preparing MOF-derived lithium aluminum titanium phosphate materials.

[0011] The third objective of this invention is to provide a composite solid electrolyte material.

[0012] The fourth objective of this invention is to provide an application of a composite solid electrolyte material in the preparation of quasi-solid-state lithium batteries and / or all-solid-state lithium batteries.

[0013] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a MOF-derived lithium aluminum titanium phosphate material, wherein the general chemical formula of the MOF-derived lithium aluminum titanium phosphate material is Li. 1+x Al x Ti 2-x (PO4)3, 0.3 ≤ x ≤ 0.5; The raw materials for preparing the MOF-derived lithium aluminum titanium phosphate material include a titanium source, which includes titanium-containing metal-organic framework materials.

[0014] Furthermore, the titanium-containing metal-organic framework material includes MIL-125; The raw materials for preparing the MOF-derived lithium aluminum titanium phosphate material also include lithium source, aluminum source and phosphorus source; Preferably, the lithium source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate; Preferably, the aluminum source includes at least one of aluminum oxide and aluminum hydroxide; Preferably, the phosphorus source includes at least one of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and ammonium phosphate.

[0015] Secondly, the present invention provides a method for preparing MOF-derived lithium aluminum titanium phosphate material, comprising: mixing a lithium source, an aluminum source, a titanium source and a phosphorus source, subjecting the mixture to hydrothermal reaction, spray drying and calcination to obtain the MOF-derived lithium aluminum titanium phosphate material.

[0016] Furthermore, the molar ratio of the lithium source, the aluminum source, the titanium source, and the phosphorus source is 1.3~1.5:0.3~0.5:1.5~1.7:3; Preferably, the mixing process includes: (a) The titanium source is dispersed in anhydrous ethanol to form a suspension with a mass concentration of 5-15 wt%, which is then ultrasonically treated and stirred to obtain solution A; (b) Dissolve the lithium source and the aluminum source in deionized water to form an aqueous solution with a mass concentration of 5-15 wt%, to obtain solution B; (c) Add the solution B dropwise to the solution A, then add the phosphorus source, and stir continuously for at least 2 hours to obtain the precursor sol; Preferably, the hydrothermal reaction temperature is 150℃~200℃, and the reaction time is 30~50h; Preferably, the calcination is a stepped calcination process, in which the temperature is increased to 300℃~500℃ at a rate of less than 5℃ / min and held for 2~5 hours, and then increased to 800℃~1000℃ at a rate of 5℃ / min and held for 1~3 hours.

[0017] Furthermore, the titanium source is a titanium-containing metal-organic framework compound, and its preparation process includes: mixing the metal source and the organic ligand in a solvent, and then subjecting them to a solvothermal reaction, centrifugal washing and vacuum drying in sequence to obtain the titanium-containing metal-organic framework compound. Preferably, the metal source comprises tetraisopropyl titanate; the organic ligand comprises terephthalic acid; Preferably, the solvent includes at least one of N,N-dimethylformamide and methanol; Preferably, the solvothermal reaction is carried out in a reaction vessel lined with polytetrafluoroethylene; the reaction system is heated from room temperature to 120~180℃ at a heating rate of 1~5℃ / min, then pressurized and kept at 120~180℃ for 10~30h, and then naturally cooled to 60~90℃ and depressurized. Preferably, the centrifugal washing uses at least one of methanol, N,N-dimethylformamide and isopropanol; the centrifugal washing speed is 1000~3000 rpm and the time is 5~20 minutes; Preferably, the vacuum drying temperature is 100~150℃ and the time is 8h~20h.

[0018] Thirdly, the present invention provides a composite solid electrolyte material, wherein the raw materials for preparing the composite solid electrolyte material include inorganic ceramic fillers, wherein the inorganic ceramic fillers include the MOF-derived lithium aluminum titanium phosphate material or the MOF-derived lithium aluminum titanium phosphate material prepared by the preparation method described above.

[0019] Furthermore, the raw materials for preparing the composite solid electrolyte material also include a polymer substrate, a lithium salt, and a binder; Preferably, the polymer substrate comprises polyethylene oxide, polypropylene carbonate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, or at least one of the organic polymers obtained by blending, grafting or block reaction of two or more of the above polymers. Preferably, the lithium salt comprises at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium dioxaborate, lithium trifluoromethanesulfonate, lithium perchlorate, and lithium hexafluorophosphate. Preferably, the adhesive comprises a hydroxyl-containing organic adhesive.

[0020] Furthermore, the composite solid electrolyte material is prepared through the following steps: The polymer substrate, inorganic ceramic filler, lithium salt and binder are mixed and then sequentially coated into a film, dried and hot-pressed to obtain the composite solid electrolyte material. Preferably, the organic solvent used in the mixing process includes at least one of N-methylpyrrolidone, acetonitrile, N,N-dimethylformamide, tetrahydrofuran, and phosphate esters; Preferably, the mass ratio of the adhesive to a portion of the organic solvent used in the mixing process is 1:8~10; Preferably, the mass ratio of the polymer substrate to the inorganic ceramic filler is 6:3~5; Preferably, when the lithium salt is lithium bis(trifluoromethanesulfonylimide) and the polymer substrate is polyethylene oxide, the molar ratio of ethylene oxide units to lithium ions in the polyethylene oxide is 15~25:1; Preferably, the amount of binder added is 1% to 3% of the total mass of the polymer substrate and the inorganic ceramic filler; Preferably, the solid content of the mixture of polymer substrate, inorganic ceramic filler, lithium salt and binder is 20 wt% to 30 wt%. Preferably, the wet film thickness of the coating is 200~300 μm; Preferably, the hot pressing treatment is performed at a temperature of 70-90°C, a pressure of 5-15 MPa, and a time of 3-10 minutes.

[0021] Fourthly, the present invention provides the application of a composite solid electrolyte material in the preparation of quasi-solid-state lithium batteries and / or all-solid-state lithium batteries.

[0022] Furthermore, the quasi-solid-state lithium battery and / or all-solid-state lithium battery also includes a cathode material, which includes at least one of nickel-cobalt-manganese ternary materials, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and nickel-cobalt-aluminum ternary materials.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The MOF-derived lithium aluminum titanium phosphate (LATP) material provided by this invention utilizes titanium-containing MOFs as a dual-functional material serving as both a titanium source and a self-sacrificing template, enabling precise control over the microstructure and pore structure of LATP. Simultaneously, this invention fully leverages the intrinsic properties of MOF materials, such as their highly ordered metal-organic coordination network, abundant nanopores, and large specific surface area, achieving atomic-level uniform mixing and spatial confinement of aluminum and titanium ions at the molecular scale. This lays the structural foundation for the subsequent generation of NASICON-structured LATP with uniform composition and controllable microstructure. Compared to conventional inorganic or organic titanium sources, titanium-containing MOFs, as precursors, can simultaneously provide titanium elements and construct multi-level porous structures in situ during thermal conversion. This results in LATP possessing not only micropores inherent to the crystal itself but also abundant mesoscale channels, which is beneficial for increasing specific surface area and porosity. This provides numerous surface and near-surface migration sites for lithium ions and constructs a continuous, low-resistance, high-speed lithium-ion transport network within the composite electrolyte. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a TEM image of the LATP-MOF provided in Embodiment 1 of the present invention; Figure 2 The AC impedance diagrams of electrolytes in different embodiments and comparative examples are shown at room temperature. Figure 3 Linear voltammetric scans of electrolytes from different embodiments and comparative examples at room temperature. Detailed Implementation

[0026] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The first aspect of this invention provides a MOF-derived lithium aluminum titanium phosphate material, wherein the general chemical formula of the MOF-derived lithium aluminum titanium phosphate material is Li. 1+x Al x Ti 2-x (PO4)3, 0.3≤x≤0.5; the raw materials for preparing the MOF-derived lithium aluminum titanium phosphate material include a titanium source, which includes titanium-containing metal-organic framework materials.

[0029] The titanium-containing metal-organic framework material includes MOF-type titanium source MIL-125 with a specific morphology (standard molecular formula of MIL-125: C). 48 H 28 O 36 Ti8, as a dual-functional material that combines titanium source and self-sacrificing template, enables precise control of the microstructure and pore structure of LATP.

[0030] This invention differs from the traditional solid-phase or sol-gel method for synthesizing LATP powder. It proposes to use metal-organic framework (MOF) materials, especially MIL-125 constructed with carboxylic acid ligands, as a precursor and structural template to derive and prepare LATP with special structures.

[0031] Furthermore, this invention not only synthesizes LATP with a specific structure but also achieves in-situ control of the surface chemical properties of the LATP filler. LATP derived from MOF may retain specific functional groups or possess higher surface energy, which significantly enhances its physical adsorption and chemical affinity with polymer matrices such as polyethylene oxide (PEO). This enhanced interfacial interaction effectively suppresses phase separation between the inorganic filler and the polymer, reduces interfacial defects, and thus constructs a stable and compact solid-solid interface within the composite electrolyte, significantly reducing interfacial ion transport resistance.

[0032] The raw materials for preparing the MOF-derived lithium aluminum titanium phosphate material also include lithium source, aluminum source and phosphorus source.

[0033] The lithium source includes at least one of carbonate (lithium carbonate Li2CO3), hydroxide (lithium hydroxide LiOH·H2O), and nitrate (lithium nitrate LiNO3).

[0034] The aluminum source includes at least one of aluminum oxide (Al2O3) and aluminum hydroxide (Al(OH)3).

[0035] The phosphorus source includes at least one of phosphoric acid (H3PO4), ammonium dihydrogen phosphate (NH4H2PO4), diammonium hydrogen phosphate ((NH4)2HPO4), and ammonium phosphate ((NH4)3PO4).

[0036] A second aspect of this invention provides a method for preparing MOF-derived lithium aluminum titanium phosphate material, comprising: mixing a lithium source, an aluminum source, a titanium source, and a phosphorus source, followed by hydrothermal reaction, spray drying, and calcination to obtain the MOF-derived lithium aluminum titanium phosphate material. Specifically, MIL-125 powder is used as a titanium source and structural template, and is uniformly mixed with a lithium source, an aluminum source, and a phosphorus source in a specific molar ratio, followed by hydrothermal reaction, spray drying, and step-by-step calcination to finally obtain LATP powder LATP-MOF with a specific structure.

[0037] This invention prepares hierarchical LATP powder that inherits some of the porous characteristics of MOF while possessing a NASICON crystal structure by precisely controlling the thermal conversion process of MOF precursors. This material not only has micropores inherent in the crystal itself but also forms abundant mesoscale channels. The fundamental advantage of this unique hierarchical porous structure lies in increasing the specific surface area and porosity of LATP, providing numerous surface and near-surface migration sites for lithium ions, and constructing a continuous three-dimensional ion transport network within the composite electrolyte.

[0038] In some preferred embodiments, the molar ratio of the lithium source, the aluminum source, the titanium source, and the phosphorus source is 1.3~1.5:0.3~0.5:1.5~1.7:3; wherein "1.3~1.5" can be, for example, 1.3, 1.4, 1.5, etc.; "0.3~0.5" can be, for example, 0.3, 0.4, 0.5, etc.; and "1.5~1.7" can be, for example, 1.5, 1.6, 1.7, etc. It should be noted that the molar ratio of the lithium source, aluminum source, titanium source, and phosphorus source refers to the molar ratio of lithium (Li), aluminum (Al), titanium (Ti), and phosphorus (P) provided by each raw material.

[0039] Preferably, 10 wt% of lithium source needs to be added as lithium supplementation agent based on the molar ratio.

[0040] In some preferred embodiments, the specific process of mixing the lithium source, aluminum source, titanium source, and phosphorus source includes: (a) First, add titanium source to anhydrous ethanol, control the solution concentration at 5 wt%~15 wt%, and dissolve it into a suspension by ultrasonic stirring (solution A).

[0041] (b) The lithium and aluminum sources are dissolved in deionized water, and the solution concentration is controlled at 5 wt% to 15 wt% (solution B).

[0042] (c) Add solution B dropwise to solution A, then slowly add phosphorus source, and stir continuously for 2 hours to obtain precursor sol.

[0043] Preferably, the temperature of the hydrothermal reaction is 150℃~200℃, for example, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, etc., and the reaction time is 30~50h, for example, 30h, 40h, 50h, etc.

[0044] Preferably, the calcination is a stepped calcination process, in which the temperature is increased to 300℃~500℃ at a rate of less than 5℃ / min and held for 2~5 hours, and then increased to 800℃~1000℃ at a rate of 5℃ / min and held for 1~3 hours.

[0045] In some preferred embodiments, the titanium source is a titanium-containing metal-organic framework compound, MIL-125, which is synthesized via a hydrothermal method using tetraisopropyl titanate and terephthalic acid as the metal source and organic ligand, respectively. The specific preparation process includes: The titanium-containing metal-organic framework compound is obtained by mixing the metal source and organic ligand in a solvent, followed by stirring, solvothermal reaction, cooling, centrifugal washing and vacuum drying.

[0046] Preferably, the solvent includes at least one of N,N-dimethylformamide (DMF) and methanol.

[0047] Preferably, the above raw materials are mixed at room temperature. To prevent hydrolysis, tetraisopropyl titanate is added dropwise in a mixed solvent composed of phthalic acid, N,N-dimethylformamide, and methanol during high-speed stirring.

[0048] Preferably, the solvothermal reaction is carried out in a reaction vessel lined with polytetrafluoroethylene; the reaction system is heated from room temperature to 120~180℃ at a heating rate of 1~5℃ / min, then pressurized and kept at 120~180℃ for 10~30h, and then naturally cooled to 60~90℃ to release the pressure.

[0049] Preferably, the centrifugal washing uses at least one of methanol, N,N-dimethylformamide and isopropanol; the centrifugal washing includes: centrifuging at 1000 rpm to 3000 rpm for 5 to 20 minutes, and centrifuging three or more times until all impurities are washed away.

[0050] The vacuum drying temperature is 100~150℃, for example, 100℃, 125℃, 150℃, etc., and the time is 8h~20h, for example, 8h, 14h, 20h, etc.

[0051] Thirdly, the present invention provides a composite solid electrolyte material, wherein the raw materials for preparing the composite solid electrolyte material include inorganic ceramic fillers, wherein the inorganic ceramic fillers include the MOF-derived lithium aluminum titanium phosphate material or the MOF-derived lithium aluminum titanium phosphate material prepared by the preparation method described above.

[0052] The composite solid-state electrolyte material provided by this invention achieves synergistic optimization of ionic conductivity, interfacial stability, and mechanical properties. Its unique morphology and high specific surface area provide a highway-like ion transport channel; the enhanced interfacial bonding ensures the long-term stability of the transport network. This invention simultaneously solves technical problems such as high ionic conductivity, high critical current density, and compatibility with lithium metal anodes, providing a solution for the development of high-performance, high-safety quasi-solid-state / all-solid-state lithium batteries.

[0053] In some preferred embodiments, the raw materials for preparing the composite solid electrolyte material also include a polymer substrate, a lithium salt, and a binder.

[0054] Preferably, the polymer substrate comprises at least one of polyethers (such as polyethylene oxide PEO), polyesters (such as polypropylene carbonate PPC, polyvinyl carbonate PEC), fluoropolymers (polyvinylidene fluoride PVDF and its copolymer PVDF-HFP), and other types (polyacrylonitrile PAN, polymethyl methacrylate PMMA), or at least one of organic polymers obtained by blending, grafting, or block reaction of two or more of the above polymers.

[0055] Preferably, the lithium salt includes at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium dioxaborate, lithium trifluoromethanesulfonate, lithium perchlorate, and lithium hexafluorophosphate.

[0056] Preferably, the binder comprises a hydroxyl-containing organic binder. Specifically, high-content LATP particles have high surface energy and limited affinity for polymer chains, making them prone to interfacial defects. Commonly, in-situ composites, hot-pressing films, or the introduction of chemical / dynamic cross-linking networks or the design of three-dimensional support frameworks are used to construct continuous and stable polymer structures. This invention utilizes an oily binder ZN-004 (commercially available model) with -OH end groups, which is strongly adsorbed onto the surface of LATP particles through hydrogen bonding and other interactions.

[0057] More preferably, the adhesive is a derivative adhesive obtained by polar solvation modification of the applicant's independently developed solution-type ceramic diaphragm adhesive ZN-004 (commercially available model). The mass ratio of ZN-004 to N-methylpyrrolidone (NMP) is 1:8~10, for example, it can be 1:8, 1:9, 1:10, etc.

[0058] In some preferred embodiments, the composite solid electrolyte material is prepared by the following steps: A slurry is prepared by mixing a polymer substrate, an inorganic ceramic filler, a lithium salt, and a binder. The slurry is then sequentially coated with a film, dried, and hot-pressed to obtain the composite solid electrolyte material.

[0059] The mass ratio of the polymer substrate to the inorganic ceramic filler is 6:3~5, preferably 6:4. The amount of lithium salt LiTFSI satisfies the ratio of ethylene oxide (EO) units to lithium ions (Li) in PEO. + The molar ratio (EO:Li) of the binder is 15-25:1. The amount of binder ZN-004 added is 1%-3% of the total mass of PEO and LATP solids. The solid content of the slurry is adjusted to between 20 wt% and 30 wt%. The organic solvent used in the mixing process includes at least one of N-methylpyrrolidone (NMP), acetonitrile, N,N-dimethylformamide, tetrahydrofuran, and phosphate esters.

[0060] The wet film thickness of the coated film is 200-300 μm. The drying process includes drying at 60°C under vacuum for 24 hours. The hot-pressing conditions are 80°C and 5-15 MPa for 3-10 minutes.

[0061] To address the contradiction between the effective amount of filler added and the blockage of ion channels, as well as the transport bottleneck caused by the physical contact between the two phases in existing technologies, this invention first employs a MOF derivatization method to construct high specific surface area LATP. Specifically, LATP particles prepared by traditional solid-state methods or sol-gel methods are typically dense, have low specific surface area, and are prone to aggregation. This invention innovatively uses a titanium-based MOF (MIL-125) as a precursor. MIL-125 possesses regular channels constructed from [TiO6] octahedra and organic ligands, and exhibits an ultra-high specific surface area. Using it as a titanium source and template, during the hydrothermal reaction, the MOF framework partially dissociates, releasing atomically dispersed Ti. 4+ It can react with Li in solution + Al 3+ PO4 3- This process achieves homogeneous mixing at the molecular scale and in-situ formation of reaction precursors. In the subsequent calcination process, a low-temperature range of 300℃–500℃ allows for the slow, orderly decomposition of the organic framework, forming abundant mesopores. A high-temperature range of 800℃–1000℃, under air conditions, ensures that titanium retains its +4 valence and completes NASICON crystallization, ultimately yielding LATP, which inherits the characteristics of MOFs. This structure possesses two core advantages: firstly, its extremely high specific surface area provides a vast number of lithium-ion surface migration sites; secondly, its abundant internal channels reduce the resistance to ion transport within the particles. This lays the foundation for the subsequent construction of efficient ion channels.

[0062] Furthermore, by leveraging the unique structure of LATP to strengthen the inorganic-organic interface bonding and construct a continuous ion transport network, specifically: in the preparation of the composite electrolyte, the high surface energy and rich surface structure of LATP enable stronger physical adsorption and entanglement with PEO polymer segments and ZN-004 binder molecules, effectively inhibiting filler agglomeration and achieving uniform dispersion at the nanoscale. PEO segments can partially embed into the surface pores of LATP, forming an interpenetrating structure, thereby constructing a robust and compact rigid-flexible interface. This strong interfacial bonding not only enhances the mechanical integrity of the membrane, but more importantly, it significantly reduces the energy barrier for lithium ions crossing the LATP-PEO interface. The LATP particles themselves constitute a continuous lithium-ion fast channel framework, while the uniformly coated PEO-LiTFSI phase acts as a bridge connecting these frameworks, achieving high room-temperature ionic conductivity (>10). -4 The key is (S / cm).

[0063] Furthermore, this invention optimizes the composite ratio and process to achieve a performance balance. Specifically, the preferred mass ratio of polymer substrate to inorganic ceramic filler is 6:4. At this ratio, the PEO matrix is ​​sufficient to fully wet and encapsulate the LATP particles, forming a strong interface and ensuring the flexibility of the membrane. Simultaneously, the LATP filler content is sufficient to construct a fully permeable ion-conducting network. If the ratio is too low, the network will be incomplete, and the conductivity will decrease; if the ratio is too high, the polymer phase will be insufficient, leading to incomplete interface encapsulation, poor film formation, and deteriorated interfacial contact. In addition, the stepwise drying process (preliminary drying under normal pressure followed by thorough vacuum drying) combined with subsequent hot pressing can effectively and slowly remove the solvent NMP, preventing macroscopic defects or stress cracking in the membrane caused by rapid solvent evaporation. Furthermore, hot pressing further eliminates micropores, increases density, and enhances the interfacial contact between the electrolyte and the electrode.

[0064] Therefore, this invention avoids the aggregation of LATP particles, thereby constructing a continuous, low-resistance high-speed lithium-ion transport network within the composite system. At the same time, it improves the interfacial affinity between the LATP filler surface and the PEO polymer segments, achieving a tighter and more stable solid-solid contact, thereby significantly reducing the interfacial ion transport energy barrier.

[0065] To address the challenges of material stability and long-term cycling in existing technologies, the microstructure and surface state of LATP are controlled to improve ion conductivity and enhance the chemical and electrochemical compatibility of the composite electrolyte (especially its inorganic phase) with the electrodes, particularly the lithium metal anode, thereby ensuring the long-term cycling stability of the battery.

[0066] In summary, this invention solves the problems of low room temperature ionic conductivity, high interfacial impedance, and difficulty in achieving both mechanical and electrochemical performance in existing LATP / polymer composite solid electrolytes due to poor dispersion of inorganic fillers, weak interfacial contact between phases, and discontinuous ion transport networks. Furthermore, by innovating the synthesis method of LATP fillers from the material source and optimizing the composite process, the overall performance of the electrolyte is systematically improved.

[0067] Fourthly, the present invention provides the application of a composite solid electrolyte material in the preparation of quasi-solid-state lithium batteries and / or all-solid-state lithium batteries.

[0068] In some preferred embodiments, the quasi-solid-state lithium battery and / or all-solid-state lithium battery further includes a cathode material, which includes at least one of nickel-cobalt-manganese ternary materials, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and nickel-cobalt-aluminum ternary materials.

[0069] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0070] Example 1 This embodiment improves a composite solid electrolyte material, the preparation process of which is as follows: (1) Synthesis of MIL-125: 3.52 g of terephthalic acid was dissolved in a mixed solvent consisting of 50 mL of N,N-dimethylformamide (DMF) and methanol (volume ratio 9:1). 2.24 mL of tetraisopropyl titanate was added, and after stirring for 1 hour, the mixture was transferred to a 100 mL polytetrafluoroethylene-lined high-pressure reactor. The reaction vessel and the mixed solution inside were heated from room temperature to 150 °C at a heating rate of 1-5 °C / min. The reaction was then maintained at 150 °C for 24 hours. After natural cooling to 90 °C and depressurization, the resulting white precipitate was washed three times by centrifugation with DMF and methanol, centrifuged at 2000 rpm for 15 min, and then vacuum dried at 120 °C for 12 hours to obtain white powder MIL-125 powder.

[0071] (2) LATP preparation: Weigh the raw materials according to the molar ratio of MIL-125:Al(NO3)3·9H2O:H3PO4:LiOH·H2O = 1.7:2.4:24:10.4 (x=0.3). Add 10wt% of lithium source as a lithium supplement to the molar ratio. Disperse 5.6515 g of MIL-125 in 40 mL of anhydrous ethanol and ultrasonically stir to form a suspension (solution A). Dissolve 1.0206 g of LiOH·H2O and 1.9141 g of Al(NO3)3·9H2O in 20 mL of deionized water (solution B). Add solution B dropwise to solution A, then slowly add 5.0000 g of H3PO4, stirring continuously for 2 hours to obtain the precursor sol. Transfer it to a high-pressure reactor and react at 180℃ for 48 hours. After cooling, the product was spray-dried, and the resulting powder was subjected to programmed calcination in air: the temperature was increased to 500℃ at 3℃ / min and held for 3 hours, and then increased to 900℃ at 5℃ / min and held for 2 hours. After natural cooling, it was ground to obtain LATP powder (denoted as LATP-MOF).

[0072] (3) Preparation of composite electrolyte membrane: PEO (Mw=600000) and LATP-MOF were weighed at a mass ratio of 6:4. LiTFSI was added, and the EO:Li ratio was controlled to be 16:1. ZN-004 binder (prepared as a solution with ZN-004:NMP=1:9) was added at 2% of the total solid mass. An appropriate amount of NMP was added, and the mixture was mixed by planetary mixer and ball milled for 5 hours to adjust the solid content of the slurry to 25wt%. The slurry was coated onto a template with a wet film thickness of 250 μm. It was then dried in a vacuum oven at 60℃ for 24 hours. Finally, it was hot-pressed at 80℃ and 10MPa for 5 minutes to obtain a self-supporting composite solid electrolyte membrane, denoted as CPE-MOF.

[0073] Transmission electron microscopy (TEM) was performed on the LATP-MOF prepared in Example 1, as follows: Figure 1 As shown in the TEM image of Example 1, the obtained material exhibits a highly regular hexahedral morphology with uniform size. This morphological feature is directly inherited from the crystal habit of its precursor MIL-125, indicating that the MOF derivation synthesis route of this invention successfully achieves topological transformation and morphological preservation from an organic-inorganic hybrid framework to a pure inorganic NASICON phase. This regular geometric shape is beneficial for the uniform dispersion and close packing of the material in the subsequent composite process.

[0074] Example 2 This embodiment provides a composite solid electrolyte material, which differs from Embodiment 1 in that the mass ratio of PEO to LATP-MOF is adjusted to 6:3.

[0075] Example 3 This embodiment provides a composite solid electrolyte material, which differs from Embodiment 1 in that the mass ratio of PEO to LATP-MOF is adjusted to 6:5.

[0076] Example 4 This embodiment provides a composite solid electrolyte material, which differs from Embodiment 1 in that: in step (2), the molar ratio is: The raw materials were weighed according to the ratio of MIL-125:Al(NO3)3·9H2O:H3PO4:LiOH·H2O = 1.6:3.2:24:11.2 (x=0.4). An additional 10 wt% lithium source was added as a lithium supplement based on the molar ratio. 5.3191 g of MIL-125 was dispersed in 40 mL of anhydrous ethanol and ultrasonically stirred to form a suspension (solution A). 1.0991 g of LiOH·H2O and 2.5522 g of Al(NO3)3·9H2O were dissolved in 20 mL of deionized water (solution B). Solution B was added dropwise to solution A, followed by slow addition of 5.0000 g of H3PO4, with continuous stirring for 2 hours to obtain the precursor sol. This was transferred to a high-pressure reactor and reacted at 150°C for 50 hours. After cooling, the product was spray-dried, and the resulting powder was subjected to programmed calcination in air: the temperature was increased to 400℃ at 3℃ / min and held for 2 hours, then increased to 800℃ at 5℃ / min and held for 3 hours. After natural cooling, it was ground to obtain LATP powder.

[0077] Example 5 This embodiment provides a composite solid electrolyte material, which differs from Embodiment 1 in that: In step (2), according to the molar ratio: Weigh the raw materials according to the ratio of MIL-125:Al(NO3)3·9H2O:H3PO4:LiOH·H2O = 1.5:4:24:12 (x=0.5), where 10wt% of the lithium source is added as a lithium supplement based on the molar ratio. Disperse 4.9866 g of MIL-125 in 40 mL of anhydrous ethanol and ultrasonically stir to form a suspension (solution A). Dissolve 1.1776 g of LiOH·H2O and 3.1902 g of Al(NO3)3·9H2O in 20 mL of deionized water (solution B). Add solution B dropwise to solution A, then slowly add 5.0000 g of H3PO4 and stir continuously for 2 hours to obtain the precursor sol. Transfer it to a high-pressure reactor and react at 150℃ for 50 hours. After cooling, the product was spray-dried, and the resulting powder was subjected to programmed calcination in air: the temperature was increased to 400℃ at 3℃ / min and held for 2 hours, then increased to 800℃ at 5℃ / min and held for 3 hours. After natural cooling, it was ground to obtain LATP powder.

[0078] Example 6 This embodiment provides a composite solid electrolyte material, which differs from Embodiment 1 in that the electrolyte membrane slurry formulation is adjusted and ZN-004 is not added.

[0079] Comparative Example 1 This comparative example provides a composite solid electrolyte material, LATP / PEO electrolyte prepared by solid-phase method. The only difference from Example 1 is step (2): MIL-125 is not used, and commercial titanium dioxide (P25, TiO2) powder with an equal molar amount of titanium is used instead of MIL-125. The lithium source is lithium carbonate (Li2CO3), the aluminum source is alumina (Al2O3), and the phosphorus source is ammonium dihydrogen phosphate (NH4H2PO4). The molar ratio of lithium (Li), aluminum (Al), titanium (Ti), and phosphorus (P) provided by each raw material remains unchanged. Zirconia balls with a particle size of 0.5 mm are used as the ball milling medium during the ball milling process. The ball-to-material ratio is 10:1, isopropanol is used as the dispersion solvent, and the ball milling time is 6 hours. After ball milling, the powder is dried under vacuum at 120°C for 10 h, and then dried, ground, and dispersed. The remaining calcination steps are the same as in Example 1, and the obtained LATP powder is denoted as LATP-S. Then, the composite electrolyte membrane is prepared according to the same step (3) as in Example 1.

[0080] Comparative Example 2 This comparative example provides a composite solid electrolyte material, using isopropyl titanate as the titanium source to prepare LATP / PEO electrolyte. The difference from Example 1 is only in step (2): MIL-125 is not used; tetraisopropyl titanate with an equal molar amount of titanium is used as the titanium source, aluminum nitrate (Al(NO3)3·9H2O) as the aluminum source, phosphoric acid (H3PO4) as the phosphorus source, and lithium hydroxide (LiOH·H2O) as the lithium source. The raw materials are weighed according to the elemental molar ratio of lithium source:aluminum source:titanium source:phosphorus source = 1.3:0.3:1.7:3. Among them, 10wt% of lithium source is added as a lithium supplement based on the molar ratio. First, tetraisopropyl titanate is added to anhydrous ethanol, and the solution concentration is controlled at 10wt%. It is dissolved into a suspension by high-speed stirring at 30°C (solution A). LiOH·H2O and Al(NO3)3·9H2O are dissolved in deionized water, and the solution concentration is controlled at 10wt% (solution B). Solution B was added dropwise to solution A, followed by slow addition of H3PO4, and the mixture was stirred continuously for 2 hours to obtain a precursor sol. This sol was then transferred to a high-pressure reactor and reacted at 120°C for 48 hours. After natural cooling, the product was spray-dried to obtain a white powder. The remaining calcination steps were the same as in Example 1, and the resulting LATP powder was designated LATP-H. Subsequently, a composite electrolyte membrane was prepared following the same steps (3) as in Example 1.

[0081] Test Example 1 The electrolyte membranes prepared in step (3) of each embodiment and comparative example were cut into circular pieces with a diameter of 9 mm, assembled into stainless steel blocking batteries, and subjected to AC impedance testing at room temperature on an electrochemical workstation. The test range was 0.1 Hz to 100,000 Hz. The ionic conductivity test results at room temperature are shown in Table 1 and Figure 2 As shown.

[0082] Table 1

[0083] As shown in Table 1, the ionic conductivity of Examples 1-5 is significantly higher than that of all comparative examples, indicating that the LATP-MOF prepared using MIL-125 as the titanium source and combined with a hydrothermal-step calcination process achieves optimal ion transport performance in PEO-based composite electrolytes. Comparative Example 1 (using commercial TiO2 instead of MIL-125) and Comparative Example 2 (using tetraisopropyl titanate as the titanium source), although using the same composite process and ratio, exhibit significantly lower electrolyte conductivity, demonstrating that the molecular-level structural characteristics of the titanium source have a decisive influence on the conductivity of the final LATP active phase.

[0084] Based on this, adjusting the ratio of lithium, aluminum, titanium, and phosphorus sources, as well as the mass ratio of PEO / LATP-MOF, can further improve the performance of the composite electrolyte. The conductivity of Examples 1-5 is consistently better than that of the comparative examples, indicating that the effective working window is between 6:3 and 6:5 for the mass ratio of PEO to LATP-MOF and 0.3≤x≤0.5. Among them, the conductivity of Example 1 is higher than that of the other examples. The mass ratio of PEO to LATP-MOF of 6:4 is the best balance point between ion pathway continuity and membrane processing stability based on the characteristics of MOF-derived fillers.

[0085] Furthermore, the conductivity of Example 6 decreased significantly because no ZN-004 binder was added, indicating that the ZN-004 binder plays a key role in inhibiting filler agglomeration, achieving uniform dispersion, and constructing a stable solid-solid interface.

[0086] Test Example 2 The electrolyte membranes prepared in each example and comparative example were cut into 9 mm diameter discs and assembled into Li|electrolyte|stainless steel blocking batteries in an argon glove box (H2O, O2 < 0.1 ppm). Linear sweep voltammetry (LSV) tests were performed at 25 °C using an electrochemical workstation at a scan rate of 5 mV / s. The oxidation voltage test results are shown in Table 2 and... Figure 3 As shown.

[0087] Table 2

[0088] As shown in Table 2, the oxidation voltages of Examples 1-6 are all no less than 5.7 V, and no less than those of Comparative Examples 1-2. Among them, the oxidation voltages of Examples 1-5 are all stably within the range of 5.8-6.2 V. This indicates that within the range of 0.3≤x≤0.5 defined in this scheme and with a specific PEO / LATP-MOF mass ratio (6:3-6:5), MOF-derived LATP materials can effectively improve the electrochemical stability window of the composite electrolyte.

[0089] Furthermore, even in Example 6 without the addition of ZN-004 binder, the oxidation voltage remained at 5.7 V, which was the same as Comparative Example 1 but significantly higher than Comparative Example 2. This indicates that the introduction of LATP-MOF material itself can broaden the electrolyte electrochemical stability window.

[0090] Test Example 3 The solid electrolyte membranes, positive electrodes, and lithium metal anodes prepared in each embodiment and comparative example were assembled into a full cell (CR2032 type). Constant current charge-discharge tests were performed at 25°C using a Blue Battery testing system. The test voltage range was 3.0~4.3 V (vs. Li). + / Li), cyclically performed at a 0.5C rate, and the discharge specific capacity and coulombic efficiency were recorded for each cycle.

[0091] Table 3

[0092] As shown in Table 3, after 200 cycles, the capacity retention of Examples 1-6 using LATP-MOF was superior to that of the comparative example, indicating that the introduction of LATP-MOF material is a key foundation for achieving long-term cycling stability. While Examples 2-6 also showed better cycling retention than the comparative example, their performance was slightly lower than that of Example 1. This suggests that, under specific ratios of lithium, aluminum, titanium, and phosphorus sources, the PEO / LATP-MOF mass ratio, and the synergistic effect of ZN-004, it is possible to simultaneously maintain high capacity retention and high coulombic efficiency.

[0093] 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 or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A MOF-derived lithium aluminum titanium phosphate material, characterized in that, The general chemical formula of the MOF-derived lithium aluminum titanium phosphate material is Li. 1+x Al x Ti 2-x (PO4)3, 0.3 ≤ x ≤ 0.5; The raw materials for preparing the MOF-derived lithium aluminum titanium phosphate material include a titanium source, which includes titanium-containing metal-organic framework materials.

2. The MOF-derived lithium aluminum titanium phosphate material according to claim 1, characterized in that, The titanium-containing metal-organic framework material includes MIL-125; The raw materials for preparing the MOF-derived lithium aluminum titanium phosphate material also include lithium source, aluminum source and phosphorus source; The lithium source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate. The aluminum source includes at least one of aluminum oxide and aluminum hydroxide; The phosphorus source includes at least one of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and ammonium phosphate.

3. The method for preparing MOF-derived lithium aluminum titanium phosphate material as described in claim 1 or 2, characterized in that, include: The MOF-derived lithium aluminum titanium phosphate material is obtained by mixing lithium, aluminum, titanium and phosphorus sources, followed by hydrothermal reaction, spray drying and calcination.

4. The preparation method according to claim 3, characterized in that, The molar ratio of the lithium source, the aluminum source, the titanium source, and the phosphorus source is 1.3~1.5:0.3~0.5:1.5~1.7:3; The mixing process includes: (a) The titanium source is dispersed in anhydrous ethanol to form a suspension with a mass concentration of 5-15 wt%, which is then ultrasonically treated and stirred to obtain solution A; (b) Dissolve the lithium source and the aluminum source in deionized water to form an aqueous solution with a mass concentration of 5-15 wt%, to obtain solution B; (c) Add the solution B dropwise to the solution A, then add the phosphorus source, and stir continuously for at least 2 hours to obtain the precursor sol; The hydrothermal reaction temperature is 150℃~200℃, and the reaction time is 30~50h; The calcination is a stepped calcination process, which involves raising the temperature to 300℃~500℃ at a rate of less than 5℃ / min and holding it for 2~5 hours, then raising the temperature to 800℃~1000℃ at a rate of 5℃ / min and holding it for 1~3 hours.

5. The preparation method according to claim 3, characterized in that, The titanium source is a titanium-containing metal-organic framework compound, and its preparation process includes: mixing the metal source and organic ligand in a solvent, and then subjecting them to a solvothermal reaction, centrifugal washing and vacuum drying to obtain the titanium-containing metal-organic framework compound. The metal source includes tetraisopropyl titanate; the organic ligand includes terephthalic acid. The solvent includes at least one of N,N-dimethylformamide and methanol; The solvothermal reaction is carried out in a reaction vessel lined with polytetrafluoroethylene; the reaction system is heated from room temperature to 120~180℃ at a heating rate of 1~5℃ / min, and then pressurized and kept at 120~180℃ for 10~30h, and then naturally cooled to 60~90℃ to release the pressure. The centrifugal washing process uses at least one of methanol, N,N-dimethylformamide, and isopropanol; the centrifugal washing speed is 1000~3000 rpm, and the time is 5~20 minutes. The vacuum drying temperature is 100~150℃, and the time is 8h~20h.

6. A composite solid electrolyte material, characterized in that, The raw materials for preparing the composite solid electrolyte material include inorganic ceramic fillers, which include the MOF-derived lithium aluminum titanium phosphate material as described in claim 1 or 2, or the MOF-derived lithium aluminum titanium phosphate material prepared by any one of the preparation methods described in claims 3 to 5.

7. The composite solid electrolyte material according to claim 6, characterized in that, The raw materials for preparing the composite solid electrolyte material also include a polymer substrate, a lithium salt, and a binder; The polymer substrate includes polyethylene oxide, polypropylene carbonate, polyvinylidene carbonate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, or at least one of the organic polymers obtained by blending, grafting or block reaction of two or more of the above polymers. The lithium salt includes at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium dioxaborate, lithium trifluoromethanesulfonate, lithium perchlorate, and lithium hexafluorophosphate. The adhesive includes hydroxyl-containing organic adhesives.

8. The composite solid electrolyte material according to claim 7, characterized in that, The composite solid electrolyte material is prepared through the following steps: The polymer substrate, inorganic ceramic filler, lithium salt and binder are mixed and then sequentially coated into a film, dried and hot-pressed to obtain the composite solid electrolyte material. The organic solvents used in the mixing process include at least one of N-methylpyrrolidone, acetonitrile, N,N-dimethylformamide, tetrahydrofuran, and phosphate esters; The mass ratio of the binder to a portion of the organic solvent used in the mixing process is 1:8~10; The mass ratio of the polymer substrate to the inorganic ceramic filler is 6:3~5; When the lithium salt is lithium bis(trifluoromethanesulfonylimide) and the polymer substrate is polyethylene oxide, the molar ratio of ethylene oxide units to lithium ions in the polyethylene oxide is 15~25:

1. The amount of the binder added is 1% to 3% of the total mass of the polymer substrate and the inorganic ceramic filler; The solid content of the mixed slurry of polymer matrix, inorganic ceramic filler, lithium salt and binder is 20 wt%~30 wt%; The wet film thickness of the coating is 200~300 μm; The hot pressing process is performed at a temperature of 70-90°C, a pressure of 5-15 MPa, and a time of 3-10 minutes.

9. The application of the composite solid electrolyte material as described in any one of claims 6 to 8 in the preparation of quasi-solid-state lithium batteries and / or all-solid-state lithium batteries.

10. The application according to claim 9, characterized in that, The quasi-solid-state lithium battery and / or all-solid-state lithium battery further includes a cathode material, which includes at least one of nickel-cobalt-manganese ternary materials, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and nickel-cobalt-aluminum ternary materials.

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