A method for preparing a rare earth metal oxide / polymer electrolyte membrane for a solid-state lithium-sulfur battery

Abstract

The application relates to a preparation method of a rare earth metal oxide / polymer electrolyte film for a solid-state lithium-sulfur battery, and relates to a preparation method of a polymer electrolyte film for improving the performance of a solid-state lithium-sulfur battery. The application mainly solves the safety risks brought by a liquid-state lithium-sulfur battery, the problems of easy dissolution of polysulfides in an electrolyte to cause a shuttle effect and the compatibility of lithium metal and an electrolyte. The method is as follows: one, preparation of a rare earth metal oxide; two, preparation of a rare earth metal oxide / polymer electrolyte precursor slurry; three, preparation of a rare earth metal oxide / polymer electrolyte film; and four, assembly of a solid-state lithium-sulfur battery. In the application, the rare earth metal oxide / polymer electrolyte film is used to obtain higher ionic conductivity, lithium ion migration and higher safety at room temperature, and practical production application is promoted. The application is applied to the field of lithium-sulfur batteries.

Description

Technical Field

[0001] This invention relates to a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. Background Technology

[0002] As one of the best candidate batteries for future energy storage systems, lithium-sulfur batteries have a capacity of 2600 Wh·kg⁻¹. -1 The theoretical specific energy of lithium-sulfur batteries is relatively high. Furthermore, sulfur in lithium-sulfur battery cathode materials has advantages such as being non-toxic, low-cost, and readily available on Earth. However, many problems remain in the commercialization of lithium-sulfur batteries, including the shuttle effect of polysulfides and the poor safety of traditional organic electrolytes. These problems lead to short lifespan and rapid capacity decay in liquid lithium-sulfur batteries, hindering their commercialization.

[0003] Therefore, research on solid-state lithium-sulfur batteries has increased rapidly in the field. Although the performance of solid-state lithium-sulfur batteries still lags far behind that of liquid lithium-sulfur batteries, significant progress has been made through the optimization and adjustment of solid electrolytes. However, solid-state lithium-sulfur batteries still face many challenges, such as the interfacial compatibility between the solid electrolyte and the positive and negative electrodes. Therefore, researchers have developed various solid electrolytes, including inorganic solid electrolytes, polymer electrolytes, and composite solid electrolytes. Among these, polymer electrolytes, replacing traditional organic electrolytes, can fundamentally solve safety issues, and polymer electrolytes exhibit good compatibility with lithium metal. Summary of the Invention

[0004] This invention addresses the issues of poor safety and easy dissolution of polysulfides in traditional organic electrolytes used in lithium-sulfur batteries by proposing a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries.

[0005] A polymer electrolyte was prepared using rare-earth metal oxide nanorods with oxygen vacancies on their surface synthesized from polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) as the polymer matrix. The addition of rare-earth metal oxides significantly reduced the crystallinity of the polymer matrix, increased the content of amorphous regions, and enhanced lithium-ion migration. The oxygen vacancies on the nanorod filler surface provided Lewis acid sites, increasing the degree of lithium salt dissociation and the concentration of free lithium ions in the system. The prepared polymer electrolyte exhibited excellent ionic conductivity, electrochemical stability window, and lithium-ion transference number at room temperature.

[0006] The objective of this invention can be achieved through the following method: a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. The method is characterized by comprising the following steps:

[0007] 1. A method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries, characterized in that the method for preparing the rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries is carried out according to the following steps:

[0008] I. Preparation of Rare Earth Metal Oxides

[0009] Preparation of cerium oxide nanorods: Dissolve 10-30g of sodium hydroxide in 20-40mL of deionized water to prepare a sodium hydroxide solution. Stir evenly at room temperature. Weigh 5-10g of Ce(NO3)3·6H2O and dissolve it in 5mL of deionized water. Stir evenly to obtain a Ce(NO3)3 solution. Add the Ce(NO3)3 solution dropwise to the sodium hydroxide solution. Then transfer the solution to a high-pressure reactor and heat at 100-120℃. After cooling to room temperature, wash the solution repeatedly with deionized water and anhydrous ethanol by centrifugation until the solution is neutral. Then dry the solution in a vacuum drying oven at 50-80℃ for 12-24h to obtain rare earth metal oxide cerium oxide nanorod materials.

[0010] Preparation of lanthanum oxide nanorods: Dissolve 0.07-0.09 g of La(NO3)3·6H2O in 20-40 mL of deionized water and stir until homogeneous at room temperature. Then, add 3-5 mL of ammonia water dropwise. Transfer the mixed solution to a high-pressure reactor and heat at 120-140 °C. After cooling to room temperature, wash repeatedly with deionized water and anhydrous ethanol by centrifugation until the solution is neutral. Dry in a vacuum drying oven at 50-80 °C for 12-24 h to obtain rare earth metal oxide lanthanum oxide nanorod materials.

[0011] Preparation of neodymium oxide nanorods: 1-3 g of Nd(NO3)3·6H2O was dissolved in 20-40 mL of deionized water and stirred at room temperature until completely dissolved. 1-3 mL of ammonia water was dissolved in 2-6 mL of deionized water and mixed evenly. The mixture was then added dropwise to the Nd(NO3)3 solution. The solution was then transferred to a high-pressure reactor and heated at 100-120 °C. After cooling to room temperature, the solution was repeatedly washed by centrifugation with deionized water and anhydrous ethanol until neutral. The solution was then vacuum dried in a vacuum drying oven at 50-80 °C for 12-24 h to obtain neodymium oxide nanorod materials.

[0012] II. Preparation of Rare Earth Metal Oxide / Polymer Electrolyte Slurry

[0013] Weigh 0.2–0.4 g of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and a certain mass of polyoxyethylene-polyoxypropylene-polyoxyethylene (P123), dissolve them in 2–4 mL of N,N-dimethylformamide, stir at room temperature for 10–12 h, then add a certain mass of rare earth metal oxide and 0.2–0.5 mL of N,N-dimethylformamide, stir for 12 h, then add a certain mass of lithium salt and continue stirring to obtain a uniform polymer electrolyte precursor slurry;

[0014] III. Preparation of Rare Earth Metal Oxide / Polymer Electrolytic Membranes

[0015] The polymer electrolyte precursor slurry was cast onto a glass plate using a casting method and then vacuum dried at 100–120°C to obtain a rare earth metal oxide / polymer electrolyte.

[0016] IV. Assembly of Solid-State Lithium-Sulfur Batteries

[0017] The positive electrode composite material of lithium-sulfur battery, conductive agent acetylene black, and binder are mixed in a certain mass ratio and stirred at room temperature for 10-12 hours to obtain a black slurry. The black slurry is coated onto a clean aluminum foil and vacuum dried at 50-80℃ for 12-24 hours to obtain a positive electrode sheet for later use. In an argon-filled glove box, the coin cell is assembled in the following order: positive electrode shell of 2025 coin cell, positive electrode sheet of lithium-sulfur battery, prepared rare earth metal oxide / polymer electrolyte membrane, lithium sheet, nickel foam, and negative electrode shell of 2025 coin cell. After sealing with a sealing machine, the battery assembly is completed, and a solid lithium-sulfur battery is obtained.

[0018] The rare earth metal oxide mentioned in step two is one of cerium oxide nanorods, lanthanum oxide nanorods, or neodymium oxide nanorods.

[0019] Furthermore, the heating times in the high-pressure reactor described in step one are 20–24 h, 13–15 h, and 10–14 h, respectively. The reaction time of the hydrothermal reaction affects the particle size, number of crystal nuclei, and grain refinement of rare earth oxides.

[0020] Furthermore, the mass of the polyoxyethylene-polyoxypropylene-polyoxyethylene mentioned in step two is 0.07 to 0.10 g.

[0021] Furthermore, the mass of the rare earth metal oxide mentioned in step two is 0.01 to 0.02 g.

[0022] Furthermore, the lithium salt mentioned in step two has a mass of 0.2–0.4 g;

[0023] Furthermore, the stirring time after adding a certain mass of lithium salt in step two is 6 to 8 hours.

[0024] Furthermore, the lithium salt added in step two is lithium bis(trifluoromethanesulfonylimide).

[0025] Furthermore, the vacuum drying time in step three is 2 to 4 hours.

[0026] Furthermore, the binder mentioned in step four is a polymer electrolyte precursor slurry.

[0027] Furthermore, the mass ratio of the lithium-sulfur battery cathode composite material, the conductive agent acetylene black, and the binder in step four is 5:2:2 to 5:2:4.

[0028] The gain effect of the present invention:

[0029] First, this invention uses Ce(NO3)3·6H2O, La(NO3)3·6H2O, and Nd(NO3)3·6H2O as raw materials to prepare cerium oxide (CeO2) nanorods, lanthanum oxide (La2O3) nanorods, and neodymium oxide (Nd2O3) nanorods respectively via hydrothermal synthesis. By controlling the hydrothermal reaction time, three nanorod materials with uniform size were synthesized. A certain content of inorganic metal oxide nanoparticles is beneficial for increasing the amorphous region of the polymer matrix, thereby improving the ionic conductivity of the polymer electrolyte; however, when the content of nanoparticles is too high, due to the influence of the surface free energy of the material, the inorganic nanoparticles will agglomerate, leading to a decrease in the ion-conducting performance of the polymer electrolyte. Therefore, compared with nanoparticles, designing uniformly sized nanorod fillers can effectively solve the problem of easy agglomeration of traditional nanoparticles, further improving the ionic conductivity and related electrochemical performance. At the same time, the interconnected rod-like morphology can provide a network for rapid lithium ion transfer.

[0030] Secondly, P123 contains hydrophilic polyethylene oxide (PEO) and hydrophobic polypropylene oxide (PPO), which can form various aggregates in polar media. During dispersion, the aggregation of P123 affects the surface tension of the metal oxide, thus forming nanomaterials with special structures. Due to the above advantages of P123, the addition of polar rare earth metal oxide fillers under the action of P123 results in a spherical stacked morphology, and PVDF-HFP, as the polymer matrix, can connect them together to form a polymer electrolyte membrane. The spherical polymer electrolyte membrane formed by the combination of these three is beneficial to the interfacial contact between the electrode and the electrolyte. Furthermore, the polymer electrolyte membrane contains a large number of interconnected pores. This porous morphology is conducive to the migration of lithium ions in the polymer electrolyte.

[0031] Finally, this invention uses a mixture of lithium-sulfur battery cathode composite material, conductive agent acetylene black (AB), and polymer electrolyte precursor slurry in a 5:2:3 ratio to obtain a solid lithium-sulfur cathode slurry. The black slurry is then coated onto clean aluminum foil and vacuum-dried at 50–80°C for 12–24 hours to obtain a solid lithium-sulfur cathode sheet. A coin cell slicing machine is used to cut the obtained lithium-sulfur battery cathode into 14 mm diameter slices, which are then assembled into a battery with a 15.6 mm anode and a 16 mm polymer electrolyte membrane. This invention features a safe manufacturing process, excellent battery performance, and is suitable for large-scale commercial production. Attached Figure Description

[0032] To more clearly illustrate the modified results of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0033] The rare earth metal oxide / polymer electrolytes are named LiTFSI / CeO2 / P123 / PVDF-HFP, LiTFSI / Nd2O3 / P123 / PVDF-HFP, and LiTFSI / La2O3 / P123 / PVDF-HFP, respectively; the polymer electrolyte membrane without nanorod filler is named LiTFSI / P123 / PVDF-HFP.

[0034] Figure 1 A schematic diagram illustrating the mechanism by which neodymium oxide fillers promote lithium salt dissociation;

[0035] Figure 2 This is a flowchart of the preparation process of polymer electrolytes;

[0036] Figure 3 The image shows the XRD pattern of cerium oxide nanorod filler.

[0037] Figure 4 The image shows the XRD pattern of lanthanum oxide nanorod filler.

[0038] Figure 5 The XRD pattern of neodymium oxide nanorod filler is shown.

[0039] Figure 6 SEM image of cerium oxide nanorod filler;

[0040] Figure 7 SEM image of lanthanum oxide nanorod filler;

[0041] Figure 8 SEM image of neodymium oxide nanorod filler;

[0042] Figure 9 SEM image of LiTFSI / P123 / PVDF-HFP polymer electrolyte;

[0043] Figure 10SEM image of LiTFSI / CeO2 / P123 / PVDF-HFP polymer electrolyte;

[0044] Figure 11 SEM image of LiTFSI / La2O3 / P123 / PVDF-HFP polymer electrolyte;

[0045] Figure 12 SEM image of LiTFSI / Nd2O3 / P123 / PVDF-HFP polymer electrolyte;

[0046] Figure 13 XPS spectra of cerium oxide nanorods: (left) Ce 3d; (right) O 1s;

[0047] Figure 14 XPS spectra of lanthanum oxide nanorods: (left) La 3d; (right) O 1s;

[0048] Figure 15 XPS spectra of neodymium oxide nanorods: (left) Nd 3d; (right) O 1s;

[0049] Figure 16 The adsorption energies of cerium oxide, lanthanum oxide, and neodymium oxide for TFSI- anions are shown.

[0050] Figure 17 The single-factor ionic conductivity of LiTFSI / P123 / PVDF-HFP;

[0051] Figure 18 The single-factor ionic conductivity of LiTFSI / CeO2 / P123 / PVDF-HFP;

[0052] Figure 19 The single-factor ionic conductivity of LiTFSI / La2O3 / P123 / PVDF-HFP;

[0053] Figure 20 The single-factor ionic conductivity of LiTFSI / Nd2O3 / P123 / PVDF-HFP;

[0054] Figure 21 Stability window diagram of LiTFSI / CeO2 / P123 / PVDF-HFP polymer electrolyte;

[0055] Figure 22 Stability window diagram of LiTFSI / La2O3 / P123 / PVDF-HFP polymer electrolyte;

[0056] Figure 23 Stability window diagram of LiTFSI / Nd2O3 / P123 / PVDF-HFP polymer electrolyte;

[0057] Figure 24 The polarization curves and impedance spectra before and after polarization of the LiTFSI / P123 / PVDF-HFP polymer electrolyte are shown. Figure 25 Polarization curves and impedance spectra before and after polarization of the LiTFSI / Nd2O3 / P123 / PVDF-HFP polymer electrolyte;

[0058] Figure 26 The constant current polarization curves are for the LiTFSI / P123 / PVDF-HFP and LiTFSI / Nd2O3 / P123 / PVDF-HFP polymer electrolytes;

[0059] Figure 27 The charge-discharge curves of a polymer electrolyte solid-state lithium-sulfur battery are shown. Detailed Implementation

[0060] The following embodiments further illustrate the above-described content of the present invention in detail. However, the subject matter of the present invention is not limited to the following embodiments, and all technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. The table below shows the experimental reagents and equipment.

[0061] Experimental drugs

[0062]

[0063] Experimental equipment

[0064]

[0065]

[0066] Specific Implementation Method 1: The preparation method of a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries according to this embodiment is carried out according to the following steps:

[0067] I. Preparation of Rare Earth Metal Oxides

[0068] Preparation of cerium oxide nanorods: Dissolve 10-30g of sodium hydroxide in 20-40mL of deionized water to prepare a sodium hydroxide solution. Stir evenly at room temperature. Weigh 5-10g of Ce(NO3)3·6H2O and dissolve it in 5mL of deionized water. Stir evenly to obtain a Ce(NO3)3 solution. Add the Ce(NO3)3 solution dropwise to the sodium hydroxide solution. Then transfer the solution to a high-pressure reactor and heat at 100-120℃. After cooling to room temperature, wash the solution repeatedly with deionized water and anhydrous ethanol by centrifugation until the solution is neutral. Then dry the solution in a vacuum drying oven at 50-80℃ for 12-24h to obtain rare earth metal oxide cerium oxide nanorod materials.

[0069] Preparation of lanthanum oxide nanorods: Dissolve 0.07-0.09 g of La(NO3)3·6H2O in 20-40 mL of deionized water and stir until homogeneous at room temperature. Then, add 3-5 mL of ammonia water dropwise. Transfer the mixed solution to a high-pressure reactor and heat at 120-140 °C. After cooling to room temperature, wash repeatedly with deionized water and anhydrous ethanol by centrifugation until the solution is neutral. Dry in a vacuum drying oven at 50-80 °C for 12-24 h to obtain rare earth metal oxide lanthanum oxide nanorod materials.

[0070] Preparation of neodymium oxide nanorods: 1-3 g of Nd(NO3)3·6H2O was dissolved in 20-40 mL of deionized water and stirred at room temperature until completely dissolved. 1-3 mL of ammonia water was dissolved in 2-6 mL of deionized water and mixed evenly. The mixture was then added dropwise to the Nd(NO3)3 solution. The solution was then transferred to a high-pressure reactor and heated at 100-120 °C. After cooling to room temperature, the solution was repeatedly washed by centrifugation with deionized water and anhydrous ethanol until neutral. The solution was then vacuum dried in a vacuum drying oven at 50-80 °C for 12-24 h to obtain neodymium oxide nanorod materials.

[0071] II. Preparation of Rare Earth Metal Oxide / Polymer Electrolyte Slurry

[0072] Weigh 0.2–0.4 g of polyvinylidene fluoride-hexafluoropropylene and a certain mass of polyoxyethylene-polyoxypropylene-polyoxyethylene and dissolve them in 2–4 mL of N,N-dimethylformamide. Stir at room temperature for 10–12 h, then add a certain mass of rare earth metal oxide and 0.2–0.5 mL of N,N-dimethylformamide and stir for 12 h. Then add a certain mass of lithium salt and continue stirring to obtain a uniform polymer electrolyte precursor slurry.

[0073] III. Preparation of Rare Earth Metal Oxide / Polymer Electrolytic Membranes

[0074] The polymer electrolyte precursor slurry was cast onto a glass plate using a casting method and then vacuum dried at 100–120°C to obtain a rare earth metal oxide / polymer electrolyte.

[0075] IV. Assembly of Solid-State Lithium-Sulfur Batteries

[0076] The positive electrode composite material of lithium-sulfur battery, conductive agent acetylene black, and binder are mixed in a certain mass ratio and stirred at room temperature for 10-12 hours to obtain a black slurry. The black slurry is coated onto a clean aluminum foil and vacuum dried at 50-80℃ for 12-24 hours to obtain a positive electrode sheet for later use. In an argon-filled glove box, the coin cell is assembled in the following order: positive electrode shell of 2025 coin cell, positive electrode sheet of lithium-sulfur battery, prepared rare earth metal oxide / polymer electrolyte membrane, lithium sheet, nickel foam, and negative electrode shell of 2025 coin cell. After sealing with a sealing machine, the battery assembly is completed, and a solid lithium-sulfur battery is obtained.

[0077] The rare earth metal oxide mentioned in step two is one of cerium oxide nanorods, lanthanum oxide nanorods, or neodymium oxide nanorods.

[0078] First, this invention uses Ce(NO3)3·6H2O, La(NO3)3·6H2O, and Nd(NO3)3·6H2O as raw materials to prepare cerium oxide, lanthanum oxide, and neodymium oxide nanorods via hydrothermal synthesis. By controlling the hydrothermal reaction time, three nanorod materials with uniform size were synthesized. A certain content of inorganic metal oxide nanoparticles is beneficial for increasing the amorphous region of the polymer matrix, thereby improving the ionic conductivity of the polymer electrolyte; however, when the nanoparticle content is too high, due to the influence of the material surface free energy, the inorganic nanoparticles will agglomerate, leading to a decrease in the ion-conducting performance of the polymer electrolyte. Therefore, compared with nanoparticles, designing uniformly sized nanorod fillers can effectively solve the problem of easy agglomeration of traditional nanoparticles, further improving ionic conductivity and related electrochemical performance. At the same time, the interconnected rod-like morphology can provide a network for rapid lithium ion transfer.

[0079] Secondly, P123 contains hydrophilic polyethylene oxide (PEO) and hydrophobic polypropylene oxide (PPO), which can form various aggregates in polar media. During dispersion, the aggregation of P123 affects the surface tension of the metal oxide, thus forming nanomaterials with special structures. Due to the above advantages of P123, the addition of polar rare earth metal oxide fillers under the action of P123 results in a spherical stacked morphology, and PVDF-HFP, as the polymer matrix, can connect them together to form a polymer electrolyte membrane. The spherical polymer electrolyte membrane formed by the combination of these three is beneficial to the interfacial contact between the electrode and the electrolyte. Furthermore, the polymer electrolyte membrane contains a large number of interconnected pores. This porous morphology is conducive to the migration of lithium ions in the polymer electrolyte.

[0080] Finally, this invention uses a mixture of lithium-sulfur battery cathode composite material, conductive agent acetylene black (AB), and polymer electrolyte precursor slurry in a 5:2:3 ratio to obtain a solid lithium-sulfur cathode slurry. The black slurry is then coated onto clean aluminum foil and vacuum-dried at 50–80°C for 12–24 hours to obtain a solid lithium-sulfur cathode sheet. A coin cell slicing machine is used to cut the obtained lithium-sulfur battery cathode into 14 mm diameter slices, which are then assembled into a battery with a 15.6 mm diameter anode and a 16 mm diameter polymer electrolyte membrane. This invention features a safe manufacturing process, excellent battery performance, and is suitable for large-scale commercial production.

[0081] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the heating times in the high-pressure reactor described in step one are 20–24 h, 13–15 h, and 10–14 h, respectively. The reaction time of the hydrothermal reaction affects the particle size and number of crystal nuclei of rare earth oxides, thus refining the grain size. Everything else is the same as in Specific Implementation Method One.

[0082] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the mass of the polyoxyethylene-polyoxypropylene-polyoxyethylene mentioned in step two is 0.07–0.10 g. Everything else is the same as in Specific Implementation Method One or Two.

[0083] Specific Implementation Method Four: This implementation method differs from one of Specific Implementation Methods One to Three in that the mass of the rare earth metal oxide mentioned in step two is 0.01 to 0.02 g. Everything else is the same as in one of Specific Implementation Methods One to Three.

[0084] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the mass of the lithium salt mentioned in step two is 0.2–0.4 g. Everything else is the same as in Specific Implementation Methods One to Four.

[0085] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the time for adding a certain mass of lithium salt and continuing stirring is 6 to 8 hours. Everything else is the same as in Specific Implementation Methods One to Five.

[0086] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the lithium salt added in step two is lithium bis(trifluoromethanesulfonyl)imide. Everything else is the same as in Specific Implementation Methods One to Six.

[0087] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the vacuum drying time in step three is 2 to 4 hours. Everything else is the same as in Specific Implementation Methods One to Seven.

[0088] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the binder mentioned in step four is a polymer electrolyte precursor slurry. Everything else is the same as in Specific Implementation Methods One to Eight.

[0089] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the mass ratio of the lithium-sulfur battery cathode composite material, conductive agent acetylene black, and binder described in step four is 5:2:2 to 5:2:4. Everything else is the same as in Specific Implementation Methods One to Nine.

[0090] Example 1

[0091] The beneficial effects of the present invention were verified through the following experiments:

[0092] The preparation method of a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries in this experiment is carried out according to the following steps:

[0093] I. Preparation of Rare Earth Metal Oxides

[0094] Preparation of cerium oxide nanorods: 19.6 g of sodium hydroxide was dissolved in 35 mL of deionized water to prepare a sodium hydroxide solution. The solution was stirred evenly at room temperature. 6.95 g of Ce(NO3)3·6H2O was weighed and dissolved in 5 mL of deionized water. The solution was stirred evenly to obtain a Ce(NO3)3 solution. The Ce(NO3)3 solution was added dropwise to the sodium hydroxide solution. The solution was then transferred to a high-pressure reactor and heated at 120 °C for 24 h. After cooling to room temperature, the solution was repeatedly washed by centrifugation with deionized water and anhydrous ethanol until it was neutral. The solution was then vacuum dried at 60 °C for 24 h in a vacuum drying oven to obtain rare earth metal oxide cerium oxide nanorod materials.

[0095] Preparation of lanthanum oxide nanorods: 0.086 g of La(NO3)3·6H2O was dissolved in 20 mL of deionized water and stirred evenly at room temperature. Then, 3 mL of ammonia water was added dropwise. The mixed solution was transferred to a high-pressure reactor and heated at 140 °C for 15 h. After cooling to room temperature, the solution was repeatedly washed by centrifugation with deionized water and anhydrous ethanol until the solution was neutral. The solution was then vacuum dried at 60 °C for 24 h in a vacuum drying oven to obtain rare earth metal oxide lanthanum oxide nanorods.

[0096] Preparation of neodymium oxide nanorods: 1.753 g of Nd(NO3)3·6H2O was dissolved in 20 mL of deionized water and stirred at room temperature until completely dissolved. 1 mL of ammonia water was dissolved in 5 mL of deionized water and mixed evenly. The mixture was then added dropwise to the Nd(NO3)3 solution. The solution was then transferred to a high-pressure reactor and heated at 120 °C for 12 h. After cooling to room temperature, the solution was repeatedly washed by centrifugation with deionized water and anhydrous ethanol until neutral. The solution was then vacuum dried at 60 °C for 24 h in a vacuum drying oven to obtain neodymium oxide nanorods.

[0097] II. Preparation of Rare Earth Metal Oxide / Polymer Electrolyte Precursor Slurry

[0098] Weigh 0.4 g of polyvinylidene fluoride-hexafluoropropylene and 0.08 g of polyoxyethylene-polyoxypropylene-polyoxyethylene and dissolve them in 3 mL of N,N-dimethylformamide. After stirring at room temperature for 12 h, add 0.02 g of rare earth metal oxide and 0.5 mL of N,N-dimethylformamide and stir for 12 h. Then add a certain mass of lithium salt and continue stirring for 6 h to obtain a uniform polymer electrolyte precursor slurry.

[0099] III. Preparation of Rare Earth Metal Oxide / Polymer Electrolytic Membranes

[0100] Polymer slurry was cast onto a glass plate using a casting method. After vacuum drying at 100°C for 2 hours, neodymium oxide / polymer electrolyte was obtained. Under the same conditions, neodymium oxide nanorods were replaced with cerium oxide nanorods and lanthanum oxide nanorods to prepare cerium oxide / polymer electrolyte and lanthanum oxide / polymer electrolyte membrane, respectively.

[0101] IV. Assembly of Solid-State Lithium-Sulfur Batteries

[0102] The positive electrode composite material of lithium-sulfur battery, conductive agent acetylene black (AB), and polymer electrolyte precursor slurry were mixed in a mass ratio of 5:2:3 and stirred at room temperature for 12 hours to obtain a black slurry. The black slurry was coated onto a clean aluminum foil and vacuum dried at 60°C for 24 hours to obtain a positive electrode sheet for later use. In an argon-filled glove box, a coin cell was assembled in the following order: positive electrode shell of 2025 coin cell, positive electrode sheet of lithium-sulfur battery, prepared rare earth metal oxide / polymer electrolyte membrane, lithium sheet, nickel foam, and negative electrode shell of 2025 coin cell. The assembly of the battery was completed by sealing with a sealing machine to obtain a solid lithium-sulfur battery for subsequent electrochemical performance testing.

[0103] The rare earth metal oxide / polymer electrolytes are named LiTFSI / Nd2O3 / P123 / PVDF-HFP, LiTFSI / CeO2 / P123 / PVDF-HFP, and LiTFSI / La2O3 / P123 / PVDF-HFP, respectively; the polymer electrolyte membrane without nanorod filler is named LiTFSI / P123 / PVDF-HFP.

[0104] Comparative Example 1

[0105] The difference between this comparative example and the previous example is that rare earth metal nanorod fillers are not added in step two; the other steps are the same as in Example 1, resulting in a LiTFSI / P123 / PVDF-HFP polymer electrolyte membrane. Figure 9As shown, the obtained LiTFSI / P123 / PVDF-HFP polymer electrolyte membrane has partially non-uniform pore sizes on its surface. (The last sentence appears to be incomplete and possibly refers to a different topic.) Figure 24 , Figure 25 As shown, by comparing the lithium-ion transference number of the polymer electrolyte before and after the addition of neodymium oxide, it can be seen that the polymer electrolyte without metal nanorod fillers has a lower lithium-ion transference number. Figure 27 As shown, the initial discharge specific capacity of the LiTFSI / P123 / PVDF-HFP solid-state lithium-sulfur battery at 0.1C is 600.4 mAh g. -1 .

[0106] Performance characterization was performed on the above comparative examples and embodiments.

[0107] 1) X-ray diffraction analysis (XRD). The phase composition of the material was determined using XRD. This paper uses the X'Pert PRO measuring instrument from Malvern Panaco (Netherlands), with a scanning range of 10-90° and a scanning speed of 5°·min. -1 Sample preparation: Place the powder sample or thin film sample evenly in the groove of the glass slide, and then insert the glass slide into the retaining seat of the XRD tester.

[0108] 2) Scanning Electron Microscopy (SEM). SEM was used to observe the morphology of the cathode material, electrolyte membrane, and cycled lithium sheet. A FEI Sirion 200 scanning electron microscope (SEM) was used, with an accelerating voltage of 0.2–30 kV and a resolution of 20 kV. Sample preparation: Dried powder samples, thin film samples, or lithium sheet samples were adhered to an aluminum sample holder using conductive adhesive. Gold was then sprayed onto the sample holder, with each gold spraying session lasting 10 seconds and an interval of 60 seconds, for a total of 10 sprays.

[0109] 3) X-ray photoelectron spectroscopy (XPS). XPS was used to analyze the elemental composition and valence state of the samples. A Thermo Scientific ESCALAB 250Xi instrument was used for the tests. The results were charge-corrected to the C1s standard peak of 285.0 eV and data were fitted using XPSPEAK41. Sample preparation: The powder samples and polymer electrolyte membranes were dried before testing.

[0110] 4) Constant Current Charge-Discharge Test. The assembled batteries were tested using the Blue Battery Testing System (CT2001A) and the Newwell Battery Testing System (CT4008T). The constant current charge-discharge test involves charging and discharging the assembled batteries under a constant current and a specific voltage range. Simultaneously, multiple parameters are recorded and analyzed, including current, voltage, time, capacity, rate performance, voltage plateau, coulombic efficiency, and differential capacity curves. Specific capacity is measured in mAh·g.-1

[0111] 5) Theoretical Calculations. Density functional theory (DFT) based on first principles was used. The binding energy was calculated using the CASTEP module. The exchange-correlated functional was chosen based on the generalized gradient approximation of the Perdew-Burke-Ernzerhof (GGA-PBE) functional.

[0112] Figure 1 This diagram illustrates the mechanism by which neodymium oxide promotes lithium salt dissociation in a method for preparing a rare-earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. Figure 1 It is known that the oxygen vacancies on the surface of the nanofiller have the function of promoting the dissociation of lithium salt, which can promote the rapid dissociation of lithium salt, increase the concentration of free lithium ions, and thus form a continuous lithium ion fast conductive network in the polymer matrix near the nanorods.

[0113] Figure 2 This is a flowchart illustrating the preparation process of the polymer electrolyte in a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. As shown in the diagram, the rare earth metal oxide / polymer electrolyte membrane is obtained through a casting method.

[0114] Figure 3 The image shows the XRD pattern of cerium oxide nanorod filler in a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. For cerium oxide, 2θ = 28.56°, 33.08°, 47.55°, 56.45° and 76.70° correspond to the (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (3 3 1) crystal planes of cerium oxide, respectively.

[0115] Figure 4 The image shows the XRD pattern of lanthanum oxide nanorod filler used in a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. Figure 4 It can be seen that 26.07°, 29.96°, 39.57°, 46.03° and 52.12° correspond to the (1 0 0), (1 0 1), (1 0 2), (1 1 0) and (1 1 2) crystal planes of lanthanum oxide, respectively.

[0116] Figure 5 The image shows the XRD pattern of neodymium oxide nanorod filler used in a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. Figure 5 As can be seen from the XRD results, 2θ = 27.86°, 40.41°, 46.37°, and 55.01° correspond to the (0 1 1), (0 1 2), (1 1 0), and (1 1 2) crystal planes of neodymium oxide, respectively. The XRD results confirm that the material was successfully prepared.

[0117] Figure 6 This is a SEM image of cerium oxide nanofiller used in a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. The image shows that the synthesized cerium oxide is a uniformly sized nanorod material.

[0118] Figure 7 The image shows a SEM image of lanthanum oxide nanofiller, which is used in a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. As can be seen from the image, the synthesized lanthanum oxide is a nanorod material with uniform size.

[0119] Figure 8 This image shows a SEM image of neodymium oxide nanofiller used in a method for preparing a rare-earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. The image reveals that the synthesized neodymium oxide is a uniformly sized nanorod material. A certain content of inorganic metal oxide nanoparticles is beneficial for increasing the amorphous region of the polymer matrix, thereby improving the ionic conductivity of the polymer electrolyte. However, when the nanoparticle content is too high, due to the influence of the material's surface free energy, the inorganic nanoparticles will aggregate, leading to a sharp decrease in the ionic conductivity of the polymer electrolyte. Therefore, compared with nanoparticles, designing uniformly sized nanorod fillers can effectively solve the problem of easy aggregation of traditional nanoparticles, further improving ionic conductivity and related electrochemical performance. Simultaneously, the interconnected rod-like morphology can provide a network for rapid lithium-ion transfer.

[0120] Figure 9 This is a SEM image of a LiTFSI / P123 / PVDF-HFP polymer electrolyte, which is a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. Under the action of polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer, the polymer electrolyte exhibits a spherical particle stacking morphology. This morphology is beneficial to improving the interfacial contact between the electrode and the electrolyte. The polyvinylidene fluoride-hexafluoropropylene matrix connects the stacked spheres to form a polymer electrolyte membrane with partially non-uniform pore size on the surface.

[0121] Figure 10 LiTFSI / CeO2 / P123 / PVDF-HFP is a method for preparing rare earth metal oxide / polymer electrolyte membranes for solid-state lithium-sulfur batteries. SEM images of the polymer electrolyte show that with the addition of cerium oxide nanofiller, the degree of deposition on the membrane surface increases and the overall pore size decreases.

[0122] Figure 11 The image shows a SEM image of a LiTFSI / La2O3 / P123 / PVDF-HFP polymer electrolyte, which is a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. It can be seen that with the addition of lanthanum oxide nanofiller, the membrane surface becomes denser and the pore size decreases.

[0123] Figure 12 SEM images of a LiTFSI / Nd₂O₃ / P₁₂₃ / PVDF-HFP polymer electrolyte membrane prepared using a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries show an increase in pores on the surface of the LiTFSI / Nd₂O₃ / P₁₂₃ / PVDF-HFP polymer electrolyte membrane, and are related to... Figure 10 , Figure 11 Compared to LiTFSI / Nd2O3 / P123 / PVDF-HFP polymer electrolyte membranes, the surface distribution is more uniform.

[0124] Figure 13 XPS spectra of cerium oxide nanorods (left) Ce 3d; (right) O 1s, representing a method for preparing rare earth metal oxide / polymer electrolyte membranes for solid-state lithium-sulfur batteries. As shown in the figure, Ce 3d... 3 / 2 and Ce3d 5 / 2 The binding energies are 898.85 eV and 880.45 eV, respectively. Among them, O... L (529.3~530.5eV) is lattice oxygen; O V (530.5~531.7eV) represents oxygen adsorbed at oxygen vacancies; the oxidation states of metal cations and the oxygen vacancy concentrations of the corresponding materials were compared and analyzed. The oxygen vacancies on the surface of the nanofiller promote the dissociation of lithium salts, accelerating their rapid dissociation and increasing the concentration of free lithium ions, thereby forming a continuous, rapidly conductive lithium-ion network in the polymer matrix near the nanorods.

[0125] The formula for calculating the concentration of oxygen vacancies is: The calculated oxygen vacancy concentration of cerium oxide is 16.2%.

[0126] Figure 14 XPS spectra of lanthanum oxide nanorods (left) La 3d; (right) O 1s, representing a method for preparing rare-earth metal oxide / polymer electrolyte membranes for solid-state lithium-sulfur batteries. As shown in the figure, La 3d... 3 / 2 and La 3d 5 / 2 The binding energies are 851.45 eV and 834.55 eV, respectively. The calculated oxygen vacancy concentration of lanthanum oxide is 42.6%.

[0127] Figure 15 XPS spectra of neodymium oxide nanorods for a method of preparing rare earth metal oxide / polymer electrolyte membranes for solid-state lithium-sulfur batteries: (left) Nd 3d; (right) O 1s; As shown in the figure, Nd 3d 3 / 2 and Nd3d 5 / 2The binding energies are 1005.6 eV and 982.3 eV, respectively. The calculated oxygen vacancy concentration of neodymium oxide is 59.8%. Compared with cerium oxide and lanthanum oxide fillers, neodymium oxide material has the highest oxygen vacancy concentration.

[0128] Figure 16 This diagram shows the adsorption energies of cerium oxide, lanthanum oxide, and neodymium oxide for TFSI- anions in a method for preparing rare earth metal oxide / polymer electrolyte membranes for solid-state lithium-sulfur batteries. To further verify the relative adsorption strengths of cerium oxide, lanthanum oxide, and neodymium oxide for TFSI- anions, the adsorption energies for TFSI- anions by these three materials were simulated and calculated. The adsorption energies for TFSI- anions by the three materials were -3.11 eV, -4.26 eV, and -11.62 eV, respectively. Neodymium oxide exhibited the strongest adsorption capacity for TFSI- anions, thus accelerating the dissociation of lithium salts more rapidly, increasing the concentration of free lithium ions, and consequently improving the lithium-ion conductivity of the polymer electrolyte.

[0129] Figure 17 The figure shows the single-factor ionic conductivity of LiTFSI / P123 / PVDF-HFP, a method for preparing rare-earth metal oxide / polymer electrolyte membranes for solid-state lithium-sulfur batteries. As can be seen from the figure, the ionic conductivity reaches its highest value of 6.09 × 10⁻⁶ when the mass ratio of polyvinylidene fluoride-hexafluoropropylene and polyoxyethylene-polyoxypropylene-polyoxyethylene is 10:2. -4 S·cm -1 .

[0130] Figure 18 The figure shows the single-factor ionic conductivity of LiTFSI / CeO2 / P123 / PVDF-HFP, a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries, prepared using a method that utilizes rare earth metal oxides / polymers. As can be seen from the figure, the ionic conductivity of the LiTFSI / CeO2 / P123 / PVDF-HFP polymer electrolyte reaches its highest value of 4.80 × 10⁻⁶ when the mass ratio of polyvinylidene fluoride-hexafluoropropylene and cerium oxide is 10:0.2. -4 S·cm -1 .

[0131] Figure 19 The figure shows the single-factor ionic conductivity of LiTFSI / La₂O₃ / P₁₂₃ / PVDF-HFP, a rare-earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. As can be seen from the figure, the ionic conductivity of the LiTFSI / La₂O₃ / P₁₂₃ / PVDF-HFP polymer electrolyte reaches its highest value of 3.88 × 10⁻⁵ when the mass ratio of polyvinylidene fluoride-hexafluoropropylene and lanthanum oxide is 10:0.5. -4 S·cm -1 .

[0132] Figure 20 The figure shows the single-factor ionic conductivity of LiTFSI / Nd₂O₃ / P₁₂₃ / PVDF-HFP polymer electrolyte membrane, prepared by a method for preparing rare earth metal oxide / polymer electrolyte membranes for solid-state lithium-sulfur batteries. As can be seen from the figure, the ionic conductivity of the LiTFSI / Nd₂O₃ / P₁₂₃ / PVDF-HFP polymer electrolyte reaches its highest value of 6.09 × 10⁻⁶ when the mass ratio of polyvinylidene fluoride-hexafluoropropylene and neodymium oxide is 10:0.5. -4 S·cm -1 .

[0133] Figure 21 This image shows the stability window of the LiTFSI / CeO2 / P123 / PVDF-HFP polymer electrolyte, a method for preparing rare earth metal oxide / polymer electrolyte membranes for solid-state lithium-sulfur batteries. When the mass ratio of PVDF-HFP to CeO2 is 10:0.2, the stability window of the LiTFSI / CeO2 / P123 / PVDF-HFP membrane is 4.01V.

[0134] Figure 22 This image shows the stability window of the LiTFSI / La2O3 / P123 / PVDF-HFP polymer electrolyte, a method for preparing rare earth metal oxide / polymer electrolyte membranes for solid-state lithium-sulfur batteries. When the mass ratio of PVDF-HFP to La2O3 is 10:0.5, the stability window of the LiTFSI / La2O3 / P123 / PVDF-HFP membrane is 4.25V.

[0135] Figure 23 This image shows the stability window of a LiTFSI / Nd₂O₃ / P₁₂₃ / PVDF-HFP polymer electrolyte membrane, prepared using a rare-earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. When the mass ratio of PVDF-HFP to Nd₂O₃ is 10:0.5, the stability window of the LiTFSI / Nd₂O₃ / P₁₂₃ / PVDF-HFP membrane is 4.33V; this relatively wide window allows for the assembly of solid-state lithium batteries using various cathode materials.

[0136] Figure 24 Polarization curves and impedance spectra before and after polarization of a LiTFSI / P123 / PVDF-HFP polymer electrolyte, prepared using a rare-earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries, are presented. According to formula t... Li+ =I ss (ΔV-I0R0) / I0(ΔV-I ss R ss The lithium-ion transference number of the LiTFSI / P123 / PVDF-HFP electrolyte was calculated to be 0.26.

[0137] Figure 25 Polarization curves and impedance spectra before and after polarization of a LiTFSI / Nd₂O₃ / P₁₂₃ / PVDF-HFP polymer electrolyte membrane prepared by a method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries. According to formula t Li+ =I ss (ΔV-I0R0) / I0(ΔV-I ss R ss The lithium-ion transference number of the LiTFSI / Nd2O3 / P123 / PVDF-HFP electrolyte was calculated to be 0.48.

[0138] Figure 26 The constant current polarization curves of LiTFSI / P123 / PVDF-HFP and LiTFSI / Nd2O3 / P123 / PVDF-HFP polymer electrolytes are shown in the figure, illustrating a method for preparing rare earth metal oxide / polymer electrolyte membranes for solid-state lithium-sulfur batteries. The figure shows the current density at 0.1 mA·cm⁻¹. -2 Constant current polarization tests were performed on the polymer electrolyte. As cycling progressed, the polarization voltage of the LiTFSI / P123 / PVDF-HFP curve fluctuated significantly. After adding Nd2O3 to the polymer electrolyte, the polarization voltage of the curve tended to stabilize and decrease.

[0139] Figure 27 The figure shows the charge-discharge curves of a polymer electrolyte solid-state lithium-sulfur battery prepared using a rare-earth metal oxide / polymer electrolyte membrane as an example of a solid-state lithium-sulfur battery preparation method. As shown, at 0.1C, the initial discharge specific capacities of the LiTFSI / P123 / PVDF-HFP battery and the LiTFSI / Nd2O3 / P123 / PVDF-HFP battery are 600.4 mAh·g, respectively. -1 and 940.8mAh·g -1 After 100 charge-discharge cycles, the discharge specific capacity was 151.9 mAh·g. -1 and 231.3 mAh·g -1 .

Claims

1. A method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries, characterized in that... A method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries is carried out according to the following steps: I. Preparation of Rare Earth Metal Oxides Preparation of cerium oxide nanorods: Dissolve 10-30 g of sodium hydroxide in 20-40 mL of deionized water to prepare a sodium hydroxide solution. Stir evenly at room temperature. Weigh 5-10 g of Ce(NO3)3·6H2O and dissolve it in 5 mL of deionized water. Stir evenly to obtain a Ce(NO3)3 solution. Add the Ce(NO3)3 solution dropwise to the sodium hydroxide solution. Then transfer the solution to a high-pressure reactor and heat at 100-120 °C. After cooling to room temperature, wash the solution repeatedly with deionized water and anhydrous ethanol by centrifugation until the solution is neutral. Then dry the solution in a vacuum drying oven at 50-80 °C for 12-24 h to obtain rare earth metal oxide cerium oxide nanorod materials. Preparation of lanthanum oxide nanorods: Dissolve 0.07-0.09 g of La(NO3)3·6H2O in 20-40 mL of deionized water and stir until homogeneous at room temperature. Then, add 3-5 mL of ammonia water dropwise. Transfer the mixed solution to a high-pressure reactor and heat at 120-140 °C. After cooling to room temperature, wash repeatedly with deionized water and anhydrous ethanol by centrifugation until the solution is neutral. Dry in a vacuum drying oven at 50-80 °C for 12-24 h to obtain rare earth metal oxide lanthanum oxide nanorod materials. Preparation of neodymium oxide nanorods: 1-3 g of Nd(NO3)3·6H2O was dissolved in 20-40 mL of deionized water and stirred at room temperature until completely dissolved. 1-3 mL of ammonia was dissolved in 2-6 mL of deionized water and mixed evenly. The mixture was then added dropwise to the Nd(NO3)3 solution. The solution was then transferred to a high-pressure reactor and heated at 100-120 °C. After cooling to room temperature, the solution was repeatedly washed by centrifugation with deionized water and anhydrous ethanol until neutral. The solution was then vacuum dried in a vacuum drying oven at 50-80 °C for 12-24 h to obtain neodymium oxide nanorod materials. II. Preparation of Rare Earth Metal Oxide / Polymer Electrolyte Precursor Slurry Weigh 0.2-0.4 g of polyvinylidene fluoride-hexafluoropropylene and a certain mass of polyoxyethylene-polyoxypropylene-polyoxyethylene and dissolve them in 2-4 mL of N,N-dimethylformamide. Stir at room temperature for 10-12 h, then add a certain mass of rare earth metal oxide and 0.2-0.5 mL of N,N-dimethylformamide, stir for 12 h, then add a certain mass of lithium salt and continue stirring to obtain a uniform polymer electrolyte precursor slurry. III. Preparation of Rare Earth Metal Oxide / Polymer Electrolytic Membranes The polymer electrolyte precursor slurry was cast onto a glass plate using a casting method and then vacuum dried at 100~120 ℃ to obtain rare earth metal oxide / polymer electrolyte. IV. Assembly of Solid-State Lithium-Sulfur Batteries The positive electrode composite material of lithium-sulfur battery, conductive agent acetylene black, and binder are mixed in a certain mass ratio and stirred at room temperature for 10-12 h to obtain a black slurry. The black slurry is coated onto a clean aluminum foil and vacuum dried at 50-80 ℃ for 12-24 h to obtain a positive electrode sheet for later use. In an argon-filled glove box, the coin cell is assembled in the following order: positive electrode shell of 2025 coin cell, positive electrode sheet of lithium-sulfur battery, prepared rare earth metal oxide / polymer electrolyte membrane, lithium sheet, nickel foam, and negative electrode shell of 2025 coin cell. After sealing with a sealing machine, the battery assembly is completed, and a solid lithium-sulfur battery is obtained. The rare earth metal oxide mentioned in step two is one of cerium oxide nanorods, lanthanum oxide nanorods, or neodymium oxide nanorods.

2. The method for preparing a rare earth metal oxide / polymer electrolyte membrane for a solid-state lithium-sulfur battery according to claim 1, characterized in that... The heating times in the high-pressure reactor mentioned in step one are 20~24 h, 13~15 h and 10~14 h respectively. The reaction time of the hydrothermal reaction affects the particle size and number of crystal nuclei of rare earth oxides, thus refining the grains.

3. The method for preparing a rare earth metal oxide / polymer electrolyte membrane for solid-state lithium-sulfur batteries according to claim 1, characterized in that... The mass of the polyoxyethylene-polyoxypropylene-polyoxyethylene mentioned in step two is 0.07~0.10 g.

4. The method for preparing a rare earth metal oxide / polymer electrolyte membrane for a solid-state lithium-sulfur battery according to claim 1, characterized in that... The mass of the rare earth metal oxide mentioned in step two is 0.01~0.02 g.

5. The method for preparing a rare earth metal oxide / polymer electrolyte membrane for a solid-state lithium-sulfur battery according to claim 1, characterized in that... The mass of the lithium salt mentioned in step two is 0.2~0.4 g.

6. The method for preparing a rare earth metal oxide / polymer electrolyte membrane for a solid-state lithium-sulfur battery according to claim 1, characterized in that... The stirring time after adding a certain mass of lithium salt in step two is 6-8 hours.

7. The method for preparing a rare earth metal oxide / polymer electrolyte membrane for a solid-state lithium-sulfur battery according to claim 1, characterized in that... The lithium salt added in step two is lithium bis(trifluoromethanesulfonylimide).

8. The method for preparing a rare earth metal oxide / polymer electrolyte membrane for a solid-state lithium-sulfur battery according to claim 1, characterized in that... The vacuum drying time mentioned in step three is 2-4 hours.

9. The method for preparing a rare earth metal oxide / polymer electrolyte membrane for a solid-state lithium-sulfur battery according to claim 1, characterized in that... The binder mentioned in step four is a polymer electrolyte precursor slurry.

10. The method for preparing a rare earth metal oxide / polymer electrolyte membrane for a solid-state lithium-sulfur battery according to claim 1, characterized in that... The mass ratio of the lithium-sulfur battery cathode composite material, conductive agent acetylene black, and binder mentioned in step four is 5:2:2 to 5:2:4.

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