Preparation method of one-dimensional nano-structure lithium ion conductor material

Abstract

The invention discloses a preparation method of a one-dimensional nano-structure lithium ion conductor material, which is characterized by comprising the following steps: (1) selecting metal salts containing lithium, lanthanum, zirconium, titanium, aluminum, phosphorus and nitrogen elements or nitrates and sulfates thereof as precursor raw materials, and proportioning according to the stoichiometric ratio of a target solid electrolyte; (2) preparing a one-dimensional nano lithium ion conductor; and (3) the prepared one-dimensional nano lithium ion conductor has a continuous linear or fibrous structure and keeps a high length-diameter ratio, the prepared one-dimensional nano lithium ion conductor has the continuous linear structure and the high length-diameter ratio, after the one-dimensional nano lithium ion conductor is uniformly dispersed in a polymer electrolyte precursor, a continuous ion transmission network penetrating through a whole membrane body can be constructed, and the performance of the polymer electrolyte is improved. And the one-dimensional nanostructure has a relatively short ion diffusion path and a large number of continuous ion transmission channels, so that the migration rate of lithium ions in the electrolyte is greatly improved.

Description

Technical Field The present invention relates to the preparation technology of lithium-ion batteries and their key materials, and particularly to a preparation method of one-dimensional nanostructured lithium-ion conductor materials, belonging to the field of new energy materials and energy storage technology. Background Art Semi-solid batteries combine the advantages of solid-state batteries and traditional liquid batteries, capable of providing relatively high ionic conductivity while enhancing battery safety and energy density to a certain extent. However, existing semi-solid polymer electrolytes still have room for improvement in terms of ionic conductivity, mechanical stability, and interfacial compatibility. Currently, commercially promising solid electrolytes are mainly divided into two categories: oxides and nitrides. Among them, oxide-based materials include lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanium oxide (LLTO), and lithium aluminum titanium phosphate oxide (LATP), while nitride-based materials are represented by lithium phosphorus oxynitride (LiPON). At present, these solid electrolyte materials are mostly prepared in the form of nanoparticles and applied in solid-state or semi-solid electrolytes. However, nanoparticles often exhibit a randomly dispersed and easily aggregated state in polymer electrolytes, resulting in poor interfacial contact between particles, forming a discontinuous ion transport network, thereby increasing the interfacial impedance and reducing the overall ionic conductivity. At the same time, it will also affect the mechanical stability and cycling performance of the electrolyte. In contrast, preparing these materials into one-dimensional linear structures can construct continuous and directional ion transport channels in the polymer matrix, shorten the ion diffusion path, and enable the materials to be uniformly dispersed in the matrix, thus significantly improving the ionic conductivity, mechanical strength, and interfacial stability of the semi-solid electrolyte. Currently, the preparation processes for one-dimensional nano lithium-ion conductors are relatively limited, and it is difficult to balance the requirements of easy industrial-scale preparation and high crystallinity, stability, etc. Currently, a patent has been published on a method for improving the performance of polymer electrolytes using nanoparticle lithium lanthanum zirconium oxide (LLZO) additives. For example, Patent CN107978793B (Title: Polymer Electrolyte, Its Preparation Method, and Lithium Metal Battery Comprising the Same) describes a method of incorporating inorganic fillers (such as nanoscale LLZO) into a polymer matrix to enhance the ionic conductivity and mechanical strength of the electrolyte. This patent details the process of preparing such composite polymer electrolytes, including uniformly dispersing LLZO nanoparticles in a polymer solution and then forming an electrolyte membrane through solution casting or other film-forming techniques. However, due to the randomly dispersed state of nanoparticles in the polymer matrix, the interfacial contact between particles is insufficient, the ion transport channels are often discontinuous, and the particles are prone to aggregation, which to a certain extent limits the improvement of the overall ionic conductivity. In view of this, the present invention proposes a process for preparing one-dimensional nano lithium ion conductors through various methods such as the self-template method, the template method, and the basalt fiber drawing method, etc. The obtained materials are uniformly dispersed in the polymer electrolyte precursor solution, and a semi-solid electrolyte is formed after in-situ curing. This method has the advantages of controllability, easy scalability, good dispersibility, etc., and can effectively improve the performance of semi-solid batteries. Summary of the Invention Aiming at the problems in the prior art that most solid electrolytes exist in the form of nanoparticles, are unevenly dispersed and prone to aggregation, resulting in high interfacial impedance, discontinuous ion transport and poor mechanical properties, the present invention provides a method for preparing one-dimensional nano lithium ion conductors suitable for semi-solid batteries, and applies this one-dimensional conductor to polymer electrolytes to construct a continuous ion transport network throughout the membrane body, significantly improving the overall ionic conductivity, reducing the interfacial impedance and enhancing the mechanical toughness and cycle stability of the membrane body. The present invention is not only applicable to traditional lithium lanthanum zirconium oxide (LLZO), but also extended to various solid electrolyte materials such as lithium lanthanum titanium oxide (LLTO), lithium aluminum titanium phosphorus oxide (LATP), and lithium phosphorus oxynitride (LiPON), etc., thus providing technical solutions for semi-solid batteries with a variety of high-performance solid electrolytes. The present invention provides the following technical solutions: A method for preparing a one-dimensional nanostructured lithium ion conductor material, comprising the following steps: (1) Select metal salts or their nitrates and sulfates containing lithium, lanthanum, zirconium, titanium, aluminum, phosphorus, and nitrogen elements as precursor raw materials, and proportion them according to the stoichiometric ratio of the target solid electrolyte; (2) Prepare one-dimensional nano lithium ion conductors through at least one of the following three preparation routes: Precipitation method: a) Dissolve the precursor metal salt in deionized water, and add a surfactant thereto to selectively adsorb on specific crystal planes and induce the formation of one-dimensional fiber or needle-like structures; b) Slowly drop the above solution into an NH4HCO3 solution preheated to 80 °C, stir and react for 30 - 60 minutes, then filter, wash and dry to obtain precursor powder; c) Mix the dried precursor powder with a lithium source, and perform pre-sintering and sintering to form continuous one-dimensional nano lithium ion conductors; Carbon nanotube template-assisted method: a) Perform acid washing or oxidation treatment on carbon nanotubes to increase surface functional groups; b) In a vacuum magnetron sputtering device, use the target solid electrolyte ceramic as the target to deposit a solid electrolyte film on the pretreated carbon nanotubes to form a core-shell structured one-dimensional composite material; c) Anneal the deposited composite material at 800 - 1000 °C to crystallize the deposited film and obtain one-dimensional nano lithium ion conductors with high crystallinity; Basalt - like drawing method: a) The precursor powder containing the target solid - state electrolyte components is melted into a glassy melt at 1200 - 1400 °C; b) In a protective atmosphere, the melt is drawn into continuous fibers with a diameter of 100 - 700 nm by a mechanical drawing device; c) The obtained fibers are annealed at 800 - 1000 °C for 2 - 4 hours to crystallize them and maintain a one - dimensional morphology; (3) The one - dimensional nano - lithium ion conductor obtained through the above steps has a continuous linear or fibrous structure and maintains a high aspect ratio. Preferably, in the steps of the precipitation method: (a) The surfactant is sodium polyacrylate, and its concentration is 1 - 3 wt% of the total solution volume; (b) The precursor solution is slowly dropped into a 0.5 M NH4HCO3 solution at a dropping rate of 0.5 mL per minute, and after stirring and reacting at 80 °C for 40 minutes, a one - dimensional needle - like coprecipitate is obtained; (c) The pre - sintering temperature is 600 - 700 °C, the holding time is 2 hours, the sintering temperature is 800 - 1000 °C, the holding time is 2 - 6 hours, and the heating rate is 2 - 5 °C / min. Preferably, in the steps of the carbon nanotube template - assisted method: (a) The carbon nanotubes are soaked in nitric acid or a mixed acid for no less than 2 hours to increase the surface carboxyl groups; (b) The magnetron sputtering voltage is controlled at about 300 V, the argon gas atmosphere pressure is about 5×10 - 3 torr, and the deposition time is 30 minutes; (c) The annealing temperature is 900 °C, and the holding time is 3 hours to crystallize the solid - state electrolyte film and form a stable one - dimensional structure with the carbon nanotubes. Preferably, in the steps of the basalt - like drawing method: (a) The melting temperature is controlled at 1300 °C - 1305 °C to obtain a glassy melt with good fluidity; (b) A constant drawing rate is adopted during the drawing process, and the fiber diameter is controlled at 100 - 700 nm; (c) The annealing temperature is 900 °C, and the holding time is 3 hours to crystallize the fibers and maintain a uniform one - dimensional morphology. Preferably, for a composite polymer electrolyte membrane, the membrane contains a one - dimensional nano - lithium ion conductor, and the mass content of the one - dimensional nano - lithium ion conductor in the polymer matrix is 0.5 - 5 wt%. Preferably, the polymer matrix is selected from polyvinylpyrrolidone (PVP), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), polyacrylonitrile (PAN), or a solution thereof with N,N-dimethylformamide (DMF) or N-methylpyrrolidone (NMP), and is prepared into a film by processes such as coating, casting, knife coating, ultraviolet curing, or thermal curing. Preferably, the one-dimensional nano lithium ion conductor constructs a continuous ion transport network throughout the film body in the film, thereby significantly improving the ionic conductivity of the film, reducing the interfacial impedance, and enhancing the mechanical toughness of the film body. Preferably, a semi-solid battery, the electrolyte layer of the semi-solid battery adopts a composite polymer electrolyte membrane. Preferably, the one-dimensional nano lithium ion conductor is selected from at least one of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanium oxide (LLTO), lithium aluminum titanium phosphate oxide (LATP), or lithium phosphorus oxynitride (LiPON), and the ionic conductivity and interfacial stability can be further improved by doping elements such as aluminum (Al), tantalum (Ta), niobium (Nb), gallium (Ga), silicon (Si), or boron (B). Beneficial effects: (1) The one-dimensional nano lithium ion conductor prepared by the present invention has a continuous linear structure and a high aspect ratio. After being uniformly dispersed in the polymer electrolyte precursor, it can construct a continuous ion transport network throughout the film body, thereby significantly improving the ionic conductivity. The one-dimensional nano structure has a short ion diffusion path and a large number of continuous ion transport channels, enabling the migration rate of lithium ions in the electrolyte to be greatly increased. Compared with traditional nanoparticle additives, it is more uniformly dispersed in the polymer matrix and is not prone to particle aggregation, thus reducing the interfacial impedance during the ion transport process. (2) In the present invention, adding a one-dimensional nano lithium ion conductor can improve the mechanical stability and interfacial compatibility of the polymer electrolyte. As a filler, the one-dimensional nano conductor can form a fibrous skeleton structure, which not only provides continuous ion channels for the electrolyte, but also enhances the mechanical toughness and tear resistance of the film body. A tight interfacial bond is formed between the conductor and the polymer matrix, significantly reducing the interfacial impedance and ion blocking phenomenon caused by interface discontinuity. In addition, due to the unique geometric morphology of the one-dimensional structure, after being dispersed in the polymer, it can effectively inhibit the growth of lithium dendrites, further improving the safety and cycle life of the semi-solid battery. Description of the Drawings Figure 1 is the XRD pattern of one-dimensional lithium lanthanum zirconium oxide nanowires; Figure 2 is the SEM image of one-dimensional lithium lanthanum zirconium oxide nanowires prepared by the precipitation method; Figure 3 is the SEM image of one-dimensional lithium lanthanum zirconium oxide nanowires prepared by the template method; Figure 4SEM image of one-dimensional lithium lanthanum zirconium oxide nanowires prepared by the method imitating basalt wire drawing. Detailed implementation manners In the present invention, the one-dimensional nano lithium ion conductor is in-situ dispersed in the polymer electrolyte, and the composite film formed by curing exhibits excellent performance in terms of ionic conductivity, mechanical strength, thermal stability, etc., and can meet the requirements of high energy density and long cycle life semi-solid batteries. Compared with the existing patent (the method using nano-particle LLZO as an additive in CN107978793B), due to the advantages of orientation and continuity of the one-dimensional nano-structure in the present invention, a more perfect ion transport network can be constructed, thereby comprehensively improving the charge and discharge performance, rate performance and safety of the battery. The molar ratio of the metal salts (including lithium hydroxide (LiOH), La(NO3)3·6H2O and ZrO(NO3)2·2H2O) used in the precursor mixture is 7.7:3.0:1.9, and further preferably 7.7:3.0:1.95, to compensate for the volatilization of lithium during sintering and ensure the uniformity of the precursor components. The present invention adopts three preparation techniques: precipitation method (self-template method), carbon nanotube (carbon nanotube) template-assisted method and the method imitating basalt wire drawing. Each process provides detailed parameters and preferred conditions, which are specifically as follows: Precipitation method (self-template method) When preparing the precursor of the lithium ion conductor, the raw materials include: Lithium source: LiOH, LiNO3, Li2CO3 or Li2SO4; Lanthanum source: La(NO3)3·6H2O or La2(SO4)3·xH2O; Titanium source: Ti(NO3)4, TiO2 suspension (for LLTO) / TiO2 (for LATP) or Ti(SO4)2; Zirconium source: ZrO(NO3)2·2H2O or Zr(SO4)2·nH2O (for LLZO); Phosphorus source: (NH4)2HPO4 or H3PO4 (for LATP); Surfactant: polyvinylpyrrolidone (PVP K30), polyethylene glycol (PEG-400), cetyltrimethylammonium bromide (CTAB), sodium dodecylbenzenesulfonate (SDBS), sodium polyacrylate, ethylene glycol; Nitride precursor: mainly using the combination of LiNO3, Li2SO4 and H3PO4 to form a nitrogen-containing structure by controlling the reaction conditions (for LiPON). (1) Prepare a mixed solution: Weigh the above metal salts, and dissolve them in 100 mL of deionized water according to the molar ratio, such as 3.0:2.0 for LLZO. (2) Adding surfactant: Sodium polyacrylate is added to the mixed solution at a concentration of about 1-3 wt%. PVP is selectively adsorbed on the high-energy crystal planes for crystal nucleation growth (such as the {100} crystal plane in LLZO, and the corresponding high-surface-energy crystal planes in LLTO or LATP) to inhibit the growth in this direction and induce the crystal to extend along other low-energy directions to form one-dimensional fiber or needle-like structures. (3) Co-precipitation reaction: The regulated solution is slowly dropped into a 0.5 M NH4HCO3 solution preheated to 80 °C (the dropping rate is preferably 0.5 mL per minute), and the reaction is carried out for 40 minutes under continuous stirring to obtain co-precipitates with uniform particle size and one-dimensional needle-like morphology. (4) Washing and drying: After filtering the co-precipitates, they are thoroughly washed with pure water and dried at 80 °C for 12 hours to obtain dry precursor powder. (5) Pre-sintering and sintering: After uniformly mixing the precursor powder with an appropriate amount of lithium hydroxide, it is placed in a MgO crucible and pre-sintered at 650 °C for 2 hours (to form an intermediate state and avoid excessive fusion). After ball milling (650 rpm, 5 hours) and tabletting (diameter about 20 mm), it is sintered at 900 °C for 4 hours (heating rate 2 °C / min) to enable the powder to spontaneously form a continuous one-dimensional nano lithium-ion conductor during the sintering process. (6) Preparation of composite polymer electrolyte: The obtained one-dimensional nano-conductor powder is dispersed in a polyvinylpyrrolidone (PVP) / N,N-dimethylformamide (DMF) solution at a ratio of 2 wt%, and ultrasonic treatment is carried out for 30 minutes to ensure uniform dispersion. Then, a composite polymer electrolyte membrane is prepared by coating and ultraviolet curing (or thermal curing) methods. The one-dimensional conductors in the membrane are uniformly distributed to construct a continuous lithium-ion transport network.

[0013] Carbon nanotube template-assisted method In this process, the raw materials are the same as those in the precipitation method, but carbon nanotubes (carbon nanotubes) are used as one-dimensional templates to achieve directional deposition and a more excellent one-dimensional structure: (1) Template pretreatment: High-quality carbon nanotubes are purchased, treated with concentrated nitric acid to introduce carboxyl groups and other functional groups, increase their hydrophilicity, and are thoroughly washed and dried for standby. (2) Magnetron sputtering deposition: In a vacuum magnetron sputtering device, a target solid electrolyte (such as LLZO, LLTO or LATP) ceramic is used as the target, and a solid electrolyte thin film is deposited on the pretreated carbon nanotube substrate. The preferred sputtering parameters are: voltage about 300 V, argon gas atmosphere pressure about 5×10 -3 torr, deposition time about 30 minutes, to form a core-shell structure one-dimensional composite material. (3) Annealing treatment: The deposited composite material is annealed in nitrogen or an inert atmosphere at 800–1000 °C for 2–4 hours to crystallize the solid electrolyte film and obtain a one-dimensional conductor with high crystallinity. (4) Composite preparation: The one-dimensional composite material is mixed with a polymer precursor solution (such as PVDF-HFP / NMP or PVP / DMF) at a ratio of 2 wt%, and uniformly dispersed through stirring and ultrasonic treatment. A film is formed by casting and thermally cured to construct a composite semi-solid electrolyte with a continuous ion transport network. Preferred conditions: The pickling treatment time of carbon nanotubes is not less than 2 hours; the sputtering parameters are strictly controlled for uniform deposition; the annealing temperature is 900 °C and the holding time is 3 hours; the mass ratio of the composite material to the polymer precursor is 1:50.

[0014] Basalt-like fiber drawing method This process uses a basalt-like natural fiber drawing method to convert precursor powder into continuous fibers to achieve a one-dimensional nanostructure. (1) Preparation of precursor powder: The precursor powder containing the target solid electrolyte components (such as LLZO, LLTO or LATP) is prepared by the co-precipitation method, and 10% excess lithium salt is added and dried at 80 °C for 12 hours. (2) Melting and fiber drawing: The dried powder is placed in a high-temperature resistant crucible and heated to 1200–1400 °C in a high-temperature furnace to form a glassy melt; the melt is drawn into continuous fibers by a mechanical fiber drawing device in a protective atmosphere, and the fiber diameter is controlled between 100 and 700 nm. (3) Annealing treatment: The drawn fibers are placed in air or an inert gas and annealed at 800–1000 °C for 2–4 hours to crystallize them into a stable solid electrolyte phase and maintain a uniform one-dimensional morphology. (4) Composite preparation: The annealed fibrous conductor is dispersed in a polyvinylpyrrolidone (PVP) / DMF solution at a ratio of 2 wt%, and after sufficient stirring and ultrasonic treatment, a film is formed by casting or blade coating and cured by ultraviolet or thermal treatment to obtain a composite polymer electrolyte film. Preferred conditions: The melting temperature is controlled at 1300 °C; a constant drawing rate is used during fiber drawing to ensure uniform fibers; the annealing temperature is 900 °C and the holding time is 3 hours.

[0015] The solid electrolytes involved in the present invention not only include the one-dimensional nano-conductors prepared by the above precipitation method, self-template method, carbon nanotube template-assisted method and basalt-like fiber drawing method, but also cover four materials: lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanium oxide (LLTO), lithium aluminum titanium phosphate oxide (LATP) and lithium phosphorus oxynitride (LiPON). The raw materials of each material may include nitrates or sulfates, and their properties can be optimized by appropriate doping. Specifically as follows: Lithium lanthanum zirconium oxide (LLZO): The main raw materials include lithium hydroxide (LiOH), lanthanum nitrate (La(NO3)3·6H2O), zirconium nitrate (ZrO(NO3)2·2H2O) or the corresponding sulfates (such as Li2SO4, La2(SO4)3, Zr(SO4)2). Commonly used doping elements are aluminum (Al), tantalum (Ta), niobium (Nb), and gallium (Ga) to improve the ionic conductivity and stability of the material. Lithium lanthanum titanium oxide (LLTO): The main raw materials include lithium hydroxide (LiOH), lanthanum nitrate (La(NO3)3·6H2O), titanium tetranitrate (Ti(NO3)4) or titanium dioxide (TiO2) suspension, or the corresponding sulfates (such as Li2SO4, La2(SO4)3, Ti(SO4)2). Commonly used doping elements are aluminum (Al), strontium (Sr), calcium (Ca), and magnesium (Mg) to improve the structure and electrochemical properties of the material. Lithium aluminum titanium phosphate (LATP): The main raw materials include lithium hydroxide (LiOH), aluminum nitrate (Al(NO3)3·9H2O), titanium tetranitrate (Ti(NO3)4), ammonium dihydrogen phosphate ((NH4)2HPO4), or the corresponding sulfates (such as Li2SO4, Al2(SO4)3, Ti(SO4)2). Commonly used doping elements are silicon (Si), zirconium (Zr), niobium (Nb), and gallium (Ga) to enhance the ionic conductivity and chemical stability of the material. Lithium phosphorus oxynitride (LiPON): The main raw materials include lithium hydroxide (LiOH), phosphoric acid (H3PO4) and an appropriate amount of oxidant, and nitrogen is introduced during the sol or sputtering process. Commonly used doping elements are silicon (Si), aluminum (Al), boron (B), and sulfur (S) to optimize the electrochemical properties and interface stability of the material. In the present invention, in the coprecipitation step, the precursor mixed solution is slowly dropped into the NH4HCO3 solution preheated to 80 °C, and the stirring time is controlled within 30 - 60 minutes, more preferably 40 minutes, to obtain precipitates with uniform particle size. In the present invention, the heat treatment and sintering process of the precursor adopt the following process parameters: the pre-sintering temperature is 600 - 700 °C, and the holding time is 2 hours; the rotation speed during ball milling is 650 rpm and the time is 5 hours; the sintering temperature is controlled at 800 - 1000 °C, the holding time is 2 - 6 hours, and the heating rate is 2 - 5 °C / min, more preferably the sintering temperature is 900 °C, the holding time is 4 hours, and the heating rate is 2 °C / min to ensure the stable crystal phase, fine grains and continuous one-dimensional structure of the one-dimensional nano lithium ion conductor. In the present invention, when the one-dimensional nano lithium-ion conductor is used as a polymer electrolyte additive, it is mixed with a polymer precursor solution (such as a solution formed by dissolving polyvinylpyrrolidone or polyacrylonitrile in N,N-dimethylformamide) at a mass ratio of 1:(1-3) wt%, more preferably 1:2 wt%, and ultrasonic or ball milling treatment is carried out to ensure its uniform dispersion. After in-situ curing, a continuous ion transport network is formed in the polymer matrix, thereby significantly improving the overall ionic conductivity and interfacial stability of the polymer electrolyte. Example 1: Preparation of one-dimensional nano lithium-ion conductor by self-template method and in-situ curing in polymer electrolyte (1) Prepare a mixed solution: Weigh La(NO3)3·6H2O, Y(NO3)3·6H2O and ZrO(NO3)2·2H2O and dissolve them in 100 mL of deionized water according to a molar ratio of 3.0:0.06:1.95. (2) Add an appropriate amount of surfactant, sodium polyacrylate, with a concentration of about 1-3 wt% of the total solution amount, to adsorb on specific crystal planes during crystal nucleus growth, inhibit the growth in this direction, promote the relatively preferential growth of other crystal planes, and induce a one-dimensional fiber or needle-like structure. (3) Slowly drop the mixed solution into a 0.5 M NH4HCO3 solution preheated to 80 °C (0.5 mL is dropped per minute), and react for 40 minutes under stirring conditions to form a uniform one-dimensional needle-like coprecipitate. (4) After filtration and washing with pure water, dry it at 80 °C for 12 hours to obtain a dry precursor powder. (5) Mix the precursor powder evenly with an appropriate amount of lithium hydroxide (and additionally add 10% excess lithium salt to compensate for lithium loss during high-temperature sintering), put it into a MgO crucible for pre-sintering: set the temperature to 650 °C and hold for 2 hours (low-temperature pre-sintering first forms an intermediate state to avoid excessive fusion of needle-like precursors). (6) Ball mill the pre-sintered product (650 rpm, 5 hours) to refine the particle size, press it into tablets (about 20 mm in diameter), and then sinter it at 900 °C for 4 hours (heating rate 2 °C / min), so that the powder spontaneously forms a continuous one-dimensional nanorod or nanofiber structure with a diameter of about 20 nanometers and a length of about 100 nanometers during sintering. (7) Disperse the prepared one-dimensional nano lithium-ion conductor powder in a polyvinylpyrrolidone (PVP) solution at a ratio of 2 wt%, and the solvent is N,N-dimethylformamide (DMF). Use ultrasonic treatment for 30 minutes to ensure the uniform dispersion of the conductor in the solution; coat the mixed solution on a pre-treated substrate, and obtain an integrated composite polymer electrolyte membrane through ultraviolet curing (or thermal curing). The one-dimensional nano conductor in the membrane is uniformly distributed, forming a continuous ion transport network. Example 2: Preparation of One-Dimensional Nano Lithium Ion Conductor by Template-Assisted Method and Its Application in Polymer Electrolyte (1) Acidify the pre-purchased carbon nanotubes (carbon nanotubes) (e.g., soak in nitric acid) to increase the surface functional group content and hydrophilicity, then wash thoroughly and dry for later use. (2) In a vacuum magnetron sputtering device, use LLZO ceramic as the target and deposit an LLZO thin film on the pretreated carbon nanotube substrate. Control the sputtering parameters: sputtering voltage 300V, atmosphere argon (pressure about 5×10-3 torr), deposition time 30 minutes, so that the LLZO thin film uniformly covers the surface of the carbon nanotubes, and the deposition thickness is about 20 nanometers, forming a core-shell structured one-dimensional composite material. (3) Heat-treat the deposited composite material appropriately to maintain the composite of carbon nanotubes and LLZO. Perform annealing treatment, anneal in a nitrogen atmosphere at 800–1000 °C for 2–4 hours to promote the crystallization of the LLZO thin film and obtain a one-dimensional nano lithium ion conductor with high crystallinity, a diameter of about 20 nanometers, and a length of about 20 micrometers. (4) Mix the one-dimensional composite material prepared by the template-assisted method with the polymer electrolyte precursor solution (e.g., PVDF-HFP / NMP solution), and the mixing ratio is that the composite material accounts for 1–5 wt% of the polymer matrix, preferably 2 wt%. After achieving uniform dispersion by stirring and ultrasonic treatment, use the casting method to form a film, and dry it by heat treatment to form a composite semi-solid electrolyte with continuous one-dimensional ion channels. Example 3: Preparation of One-Dimensional Nano Lithium Ion Conductor by Imitating Basalt Drawing Method and Its Application in Polymer Electrolyte (1) Mix the dried precursor powder prepared by the co-precipitation method (after supplementing an excessive lithium source) evenly and place it in a high-temperature resistant crucible. (2) Heat the precursor powder in a high-temperature furnace to 1200–1400 °C until it reaches the molten state and transforms into a glassy melt. (3) Use a mechanical drawing device to draw the molten precursor into continuous fibers in a protective atmosphere, and control the fiber diameter between 100 and 700 nm. Place the drawn fibers in air or inert gas and anneal at 800–1000 °C for 2–4 hours to crystallize them into a stable garnet structure and ensure uniform one-dimensional morphology. (4) Mix the annealed fibrous LLZO nanomaterial with the polymer precursor solution (e.g., polyvinylpyrrolidone / DMF solution) at 2 wt%, and achieve uniform dispersion through sufficient stirring and ultrasonic treatment; form a film from the mixed solution by casting or scraping, and cure it by ultraviolet or heat treatment to finally obtain a composite semi-solid electrolyte with one-dimensional nano LLZO with a diameter of about 50 nanometers and a length of about 500 nanometers uniformly distributed in the polymer matrix. Comparative Example: Preparation of Nano-LLZO Composite Polymer Electrolyte (1) Mix LLZO nanoparticles with a polymer precursor solution (such as polyvinylpyrrolidone / DMF solution) at 2 wt%, and achieve uniform dispersion through sufficient stirring and ultrasonic treatment; form a film from the mixed solution by casting or blade coating, and cure it by ultraviolet or heat treatment to finally obtain a composite semi-solid electrolyte with one-dimensional nano-LLZO uniformly distributed in the polymer matrix. Preparation process Capacity retention rate at 25℃ / 1C / 200 weeks <![CDATA[Ionic conductivity s / cm, 10 -4 > Example 1 Self-template method 94.3％ 9.36 Example 2 Template-assisted method 95.1％ 10.18 Example 3 Imitation basalt wire drawing method 94.5％ 8.24 Comparative example Nano-LLZO 90.2％ 7.4 In summary, the one-dimensional nano lithium ion conductor prepared by the present invention has a continuous linear structure and a high aspect ratio. After being uniformly dispersed in the polymer electrolyte precursor, it can construct a continuous ion transport network throughout the film body, thereby significantly improving the ionic conductivity. The one-dimensional nano structure has a short ion diffusion path and a large number of continuous ion transport channels, which greatly increases the migration rate of lithium ions in the electrolyte. Compared with traditional nanoparticle additives, it is more uniformly dispersed in the polymer matrix and is not prone to particle aggregation, thus reducing the interfacial impedance during ion transport.

Claims

1. A method for preparing a one-dimensional nanostructured lithium ion conductor material, characterized in that: The following steps are involved: (1) Selecting metal salts containing lithium, lanthanum, zirconium, titanium, aluminum, phosphorus, and nitrogen or their nitrates and sulfates as precursor raw materials, and proportioning them according to the stoichiometric ratio of the target solid electrolyte; (2) preparing a one-dimensional nanolithium ion conductor by at least one of the following three preparation routes: Precipitation method: a) dissolving the precursor metal salt in deionized water, and adding a surfactant (one or any combination of polyvinyl pyrrolidone (PVP K30), polyethylene glycol (PEG-400), cetyl ammonium bromide (CTAB), sodium dodecylbenzene sulfonate (SDBS), sodium polyacrylate, ethylene glycol, etc.) thereto to selectively adsorb on a specific crystal plane and induce the formation of a one-dimensional fiber or needle-like structure; b) slowly adding the above solution dropwise to a NH4HCO3 solution preheated to 80°C, stirring and reacting for 30 to 60 minutes, then filtering, washing and drying to obtain a precursor powder; c) mixing the dried precursor powder with a lithium source, pre-sintering and sintering to form a continuous one-dimensional nano lithium ion conductor; Carbon nanotube template-assisted method: a) acid washing or oxidation treatment of the carbon nanotubes to increase surface functional groups; b) in a vacuum magnetron sputtering device, using a target solid electrolyte ceramic as a target material, depositing a solid electrolyte film on the pretreated carbon nanotubes to form a one-dimensional composite material with a core-shell structure; c) annealing the deposited composite material at 800-1000° C. to crystallize the deposited film to obtain a one-dimensional nano lithium ion conductor with high crystallinity; Imitation basalt wire drawing method: a) melting a precursor powder containing a target solid electrolyte component into a glassy melt at 1200-1400° C.; b) drawing the melt into continuous fibers with a diameter of 100 to 700 nm using a mechanical drawing device in a protective atmosphere; c) annealing the obtained fiber at 800-1000° C. for 2-4 hours to crystallize the fiber and maintain a one-dimensional morphology; (3) The one-dimensional nano lithium ion conductor obtained by the above steps has a continuous linear or fibrous structure and maintains a high aspect ratio.

2. The method for preparing the one-dimensional nanostructured lithium ion conductor material according to claim 1, characterized in that: In the steps of the precipitation method: (a) the surfactant is sodium polyacrylate, and its concentration is 1 to 3 wt% of the total solution; (b) slowly adding the precursor solution to a 0.5 M NH4HCO3 solution at a dropping rate of 0.5 mL per minute, and stirring the reaction at 80° C. for 40 minutes to obtain a one-dimensional needle-shaped coprecipitate; (c) The pre-sintering temperature is 600-700°C, the holding time is 2 hours, the sintering temperature is 800-1000°C, the holding time is 2-6 hours, and the heating rate is 2-5°C / min.

3. The method for preparing the one-dimensional nanostructured lithium ion conductor material according to claim 1, characterized in that: The steps of the carbon nanotube template-assisted method are: (a) the carbon nanotubes are immersed in nitric acid or mixed acid for not less than 2 hours to increase the surface carboxyl groups; (b) The magnetron sputtering voltage was controlled at about 300 V, the argon atmosphere pressure was about 5×10-3 torr, and the deposition time was 30 minutes; (c) The annealing temperature is 900°C and kept for 3 hours to allow the solid electrolyte film to crystallize and form a stable one-dimensional structure with the carbon nanotubes.

4. The method for preparing the one-dimensional nanostructured lithium ion conductor material according to claim 1, characterized in that: In the steps of the basalt-like wire drawing method: (a) The melting temperature is controlled at 1300°C-1305°C to obtain a glassy melt with good fluidity; (b) A constant drawing rate is used during the drawing process, and the fiber diameter is controlled within the range of 100 to 700 nm; (c) The annealing temperature is 900 °C and kept for 3 hours to allow the fibers to crystallize and maintain a uniform one-dimensional morphology.

5. A composite polymer electrolyte membrane, characterized in that The film contains a one-dimensional nano lithium ion conductor, and the mass content of the one-dimensional nano lithium ion conductor in the polymer matrix is ​​0.5-5wt%.

6. A composite polymer electrolyte membrane according to claim 5, characterized in that: The polymer matrix is ​​selected from polyvinyl pyrrolidone (PVP), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), polyacrylonitrile (PAN) or a solution thereof with N,N-dimethylformamide (DMF) or N-methylpyrrolidone (NMP), and is prepared into a film by coating, casting, doctor blading, UV curing or thermal curing processes.

7. A composite polymer electrolyte membrane according to claim 5 or 6, characterized in that: The one-dimensional nanolithium ion conductor constructs a continuous ion transport network throughout the membrane, thereby significantly improving the ionic conductivity of the membrane, reducing the interfacial impedance and enhancing the mechanical toughness of the membrane.

8. A semi-solid battery, characterized in that: The electrolyte layer of the semi-solid battery adopts a composite polymer electrolyte membrane.

9. A semi-solid battery according to claim 8, characterized in that: The one-dimensional nano lithium ion conductor is selected from at least one of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanium oxide (LLTO), lithium aluminum titanium phosphorus oxide (LATP) or lithium phosphorus oxynitride (LiPON), and the ion conductivity and interface stability can be further improved by doping elements such as aluminum (Al), tantalum (Ta), niobium (Nb), gallium (Ga), silicon (Si) or boron (B).

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