Graphene supported nanoporous titania lithium-sulfur battery cathode support material, method of making and lithium-sulfur battery

Abstract

This invention discloses a graphene-supported nanoporous titanium dioxide cathode carrier material for lithium-sulfur batteries, its preparation method, and a lithium-sulfur battery based on this carrier material, belonging to the technical field of nanomaterials. The material uses the triblock copolymer Pluronic F127 as a template agent and glycerol as a confining solvent, and is stirred in an oil bath to construct a titanium dioxide nanoporous structure on pristine graphene. The pore size is mainly distributed at 4.0 nm, effectively increasing the specific surface area of ​​the material while retaining the excellent conductivity of graphene. Benefiting from the strong binding energy between TiO2 and lithium polysulfides, this invention effectively suppresses the dissolution and shuttle effect of lithium polysulfides by in-situ self-assembling ultrathin nanoporous TiO2 on pristine graphene. Simultaneously, the excellent conductivity of graphene accelerates electron transport, thereby improving the discharge specific capacity and cycle performance of the lithium-sulfur battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium-sulfur battery cathode materials, and relates to a lithium-sulfur battery cathode support material, particularly a graphene-supported nanoporous titanium dioxide lithium-sulfur battery cathode support material, its preparation method, and a lithium-sulfur battery. Background Technology

[0002] In recent years, research and development has increasingly focused on lithium-sulfur batteries. Elemental sulfur boasts a theoretical specific capacity of 1675 mAh / g and a theoretical specific energy of 2600 Wh / kg, making it a promising candidate for next-generation high-energy-density rechargeable batteries. Furthermore, sulfur is abundant, environmentally friendly, and inexpensive, offering excellent application prospects. However, several issues limit the practical application of lithium-sulfur batteries. For example, sulfur's insulating properties hinder rapid electrochemical reactions, resulting in sluggish kinetics. The shuttle effect of lithium polysulfides leads to the loss of active material and capacity decay. Therefore, improving the conductivity of the cathode material in lithium-sulfur batteries and limiting the shuttle effect of lithium polysulfides are key to solving these problems.

[0003] The physical confinement effect of the porous structure of carbon materials alone has limited ability to restrict the shuttle effect of lithium polysulfides. However, titanium dioxide (TiO2) exhibits good adsorption properties for lithium polysulfides, effectively limiting the shuttle effect during the charge-discharge process of lithium-sulfur batteries. Nevertheless, TiO2 is a semiconductor material with poor electrical conductivity, exhibiting low electronic and ionic conductivity, which hinders electron and ion transport, reducing battery performance. Furthermore, TiO2 particles tend to agglomerate, which is detrimental to sulfur loading.

[0004] Graphene, a two-dimensional π-π conjugated structure with ultra-high specific surface area and conductivity, can serve as a carrier for TiO2, improving its dispersion and inhibiting aggregation, forming interconnected ultrafast electron conduction pathways, thereby enhancing its adsorption and conductivity for lithium polysulfides. In-situ self-assembly of an ultrathin nanoporous TiO2 layer on pristine graphene effectively increases the material's specific surface area through its mesoporous structure, suppressing the dissolution and shuttle effect of lithium polysulfides. The nanopores promote ion transport and diffusion, while graphene's excellent conductivity accelerates electron transport, thus improving the discharge specific capacity and cycle performance of lithium-sulfur batteries. However, due to graphene's inertness, large and aggregated TiO2 particles often form on its surface. Although graphene oxide or heavily oxidized graphene can be used, the irreversible destruction of the π-π conjugated structure, even under harsh conditions and complex reduction processes, will compromise its performance. Therefore, we propose a method for using graphene-supported nanoporous TiO2 (G@np-TiO2) as a cathode carrier in lithium-sulfur batteries to improve their capacity and cycle performance. Summary of the Invention

[0005] The purpose of this invention is to provide a graphene-supported nanoporous titanium dioxide lithium-sulfur battery cathode carrier material, its preparation method, and a lithium-sulfur battery based on this carrier material. The material prepared by the method of this invention improves the discharge specific capacity and cycle performance of lithium-sulfur batteries.

[0006] To achieve the objectives described in this invention, the following technical solution is adopted:

[0007] A method for preparing graphene-supported nanoporous titanium dioxide G@np-TiO2 lithium-sulfur battery cathode support material includes the following steps:

[0008] (1) Add the triblock copolymer Pluronic F127 to tetrahydrofuran, add acetic acid and hydrochloric acid dropwise to the solution, and then add tetrabutyl titanate dropwise to form a golden yellow solution. Stir evenly and place in an oven to evaporate to obtain titanium dioxide single micelle gel.

[0009] (2) Take the titanium dioxide single micelle gel obtained in step (1), dissolve it in anhydrous ethanol, add tetramethylbenzidine and glycerol, and stir to obtain solution A; disperse graphene in anhydrous ethanol by ultrasonication to obtain solution B, mix solution B and solution A evenly and stir in an oil bath, and wash and dry the product after completion.

[0010] (3) The product obtained in step (2) is calcined at high temperature in an inert gas atmosphere to obtain G@np-TiO2 composite material.

[0011] Further, in step (1), the mass ratio of the triblock copolymer Pluronic F127 to the volume ratio of tetrahydrofuran is 1-2 g: 10-30 mL, the volume fraction of the tetrabutyl titanate is 3-10%, the acetic acid is anhydrous acetic acid, and the hydrochloric acid is concentrated hydrochloric acid; the evaporation temperature of the oven is 30-50 ℃, and the time is 16-48 h.

[0012] Furthermore, in step (2), the graphene is raw graphene and does not require secondary processing. The volume fraction of glycerol in solution A is 20-60%, and the concentration of graphene in solution B is 2-5 mg / mL.

[0013] Furthermore, in step (2), the oil bath temperature is 80-120 ℃, the stirring speed is 300-400 rpm, the time is 3-6 h, the washing solvent is ethanol, and the drying conditions are vacuum drying at 30-60 ℃ for 12-24 h.

[0014] Furthermore, in step (3), the calcination temperature is 350-400 ℃, the heating rate is 2-5 ℃ / min, and the holding time is 2-5 h.

[0015] A graphene-supported nanoporous titanium dioxide lithium-sulfur battery cathode carrier material was prepared using the above method.

[0016] Furthermore, the titanium dioxide is in situ loaded on the graphene surface to form a nanoporous structure with a pore size of 2-10 nm.

[0017] A lithium-sulfur battery is prepared using the above-mentioned graphene-supported nanoporous titanium dioxide lithium-sulfur battery cathode carrier material.

[0018] The beneficial effects of this invention are as follows:

[0019] This invention utilizes the triblock copolymer Pluronic F127 as a template agent and glycerol as a confining solvent to construct a TiO2 nanoporous structure on the surface of pristine graphene. First, titanium dioxide single-micelle gels are prepared by evaporation of tetrahydrofuran. Then, the single micelles and graphene are mixed in an ethanol / glycerol solvent under stirring to initiate the sol-gel process. High-viscosity glycerol is used as a co-solvent because it can induce the self-assembly of single micelles in the spatially confined direction, and simultaneously, by strongly adhering to the titanium single micelles, it slows down the hydrolysis and condensation rates of titanium oligomers. This promotes the high-density, uniform growth of TiO2 on the graphene surface. The mesoporous structure on the surface effectively increases the specific surface area of ​​the material, reduces irregular aggregation of TiO2, and the abundant nanopores promote ion transport and diffusion. Given the good adsorption of lithium polysulfides by the metal oxide TiO2, which suppresses the shuttle effect of lithium polysulfides, and the excellent conductivity of the graphene substrate, electron transport is accelerated. The G@np-TiO2 prepared in this invention serves as a sulfur carrier, thereby improving the discharge specific capacity and cycle performance of lithium-sulfur batteries. Attached Figure Description

[0020] Figure 1 This is an X-ray diffraction pattern of G@np-TiO2 in an embodiment of the present invention.

[0021] Figure 2 This is a transmission electron microscope (TEM) image of G@np-TiO2 in an embodiment of the present invention.

[0022] Figure 3 The nitrogen isotherm adsorption-desorption curves and pore size distribution diagrams of G@np-TiO2 in this embodiment of the invention are shown.

[0023] Figure 4 This is the first charge-discharge curve of G@np-TiO2 / S at a current density of 0.05 C in an embodiment of the present invention.

[0024] Figure 5 The graph shows the cycling performance of G@np-TiO2 / S and acetylene black / sulfur composite cathode materials at a current density of 0.5 C in the embodiments of the present invention. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] Example 1

[0027] The preparation methods of G@np-TiO2 lithium-sulfur battery cathode support material and lithium-sulfur battery are as follows:

[0028] (1) 1.5 g of triblock copolymer Pluronic F127 was added to 30 mL of tetrahydrofuran, acetic acid and hydrochloric acid were added dropwise to the solution, and finally 3 mL of tetrabutyl titanate was added dropwise to form a golden yellow solution. The solution was stirred evenly and placed in an oven at 45 °C for 24 h to evaporate and obtain a yellowish-white titanium dioxide single micelle gel. The acetic acid was anhydrous acetic acid and the hydrochloric acid was concentrated hydrochloric acid.

[0029] (2) Take 1 g of titanium gel obtained in step (1), dissolve it in 5 mL of anhydrous ethanol, add 3 mL of tetramethylbenzidine and 10 mL of glycerol, and stir to obtain solution A; disperse 40 mg of graphene in 10 mL of anhydrous ethanol to obtain solution B, mix it with solution A and stir in an oil bath at 100 °C for 6 h at a stirring speed of 350 rpm. After the oil bath is completed, wash the product with ethanol and place it in a vacuum drying oven at 60 °C for 12 h.

[0030] (3) The product obtained in step (2) was calcined at 400 °C in an argon atmosphere with a heating rate of 2 °C / min and a holding time of 3 h to obtain G@np-TiO2.

[0031] (4) The composite material obtained in step (3) was mixed with sulfur at a mass ratio of 1:4 and milled. The mixture was heated to 155 °C and kept at that temperature for 12 h in a polytetrafluoroethylene reactor. G@np-TiO2 / S was obtained by melt diffusion method.

[0032] (5) G@np-TiO2 / S obtained in step (4) is milled and mixed with conductive carbon black and polyvinylidene fluoride in a mass ratio of 8:1:1. N-methylpyrrolidone is added dropwise to adjust the solid content to 25% to prepare a positive electrode slurry. Then it is coated on an aluminum foil current collector, dried, pressed, and assembled into a CR2032 button cell in a glove box.

[0033] Example 2

[0034] The preparation methods of G@np-TiO2 lithium-sulfur battery cathode support material and lithium-sulfur battery are as follows:

[0035] (1) 1.5 g of triblock copolymer Pluronic F127 was added to 30 mL of tetrahydrofuran, acetic acid and hydrochloric acid were added dropwise to the solution, and finally 3 mL of tetrabutyl titanate was added dropwise to form a golden yellow solution. The solution was stirred evenly and placed in an oven at 45 °C for 24 h to evaporate and obtain a yellowish-white titanium dioxide single micelle gel. The acetic acid was anhydrous acetic acid and the hydrochloric acid was concentrated hydrochloric acid.

[0036] (2) Take 0.1 g of the titanium gel obtained in step (1), dissolve it in 5 mL of anhydrous ethanol, add 3 mL of tetramethylbenzidine and 2 mL of glycerol, and stir to obtain solution A; disperse 20 mg of graphene in 10 mL of anhydrous ethanol to obtain solution B, mix it with solution A and stir in an oil bath at 100 °C for 6 h at a stirring speed of 350 rpm. After the oil bath is completed, wash the product with ethanol and place it in a vacuum drying oven at 60 °C for 12 h.

[0037] (3) The product obtained in step (2) was calcined at 400 °C in an argon atmosphere with a heating rate of 2 °C / min and a holding time of 3 h to obtain G@np-TiO2.

[0038] (4) The composite material obtained in step (3) was mixed with sulfur at a mass ratio of 1:3 and milled. The mixture was heated to 155 °C and kept at that temperature for 12 h in a polytetrafluoroethylene reactor. G@np-TiO2 / S was obtained by melt diffusion method.

[0039] (5) G@np-TiO2 / S obtained in step (4) is milled and mixed with conductive carbon black and polyvinylidene fluoride in a mass ratio of 8:1:1. N-methylpyrrolidone is added dropwise to adjust the solid content to 25% to prepare a positive electrode slurry. Then it is coated on an aluminum foil current collector, dried, pressed, and assembled into a CR2032 button cell in a glove box.

[0040] Example 3

[0041] The preparation methods of G@np-TiO2 lithium-sulfur battery cathode support material and lithium-sulfur battery are as follows:

[0042] (1) 1.5 g of triblock copolymer Pluronic F127 was added to 30 mL of tetrahydrofuran, acetic acid and hydrochloric acid were added dropwise to the solution, and finally 3 mL of tetrabutyl titanate was added dropwise to form a golden yellow solution. The solution was stirred evenly and placed in an oven at 45 °C for 24 h to evaporate and obtain a yellowish-white titanium dioxide single micelle gel. The acetic acid was anhydrous acetic acid and the hydrochloric acid was concentrated hydrochloric acid.

[0043] (2) Take 0.5 g of the titanium gel obtained in step (1), dissolve it in 5 mL of anhydrous ethanol, add 3 mL of tetramethylbenzidine and 5 mL of glycerol, and stir to obtain solution A; disperse 30 mg of graphene in 10 mL of anhydrous ethanol to obtain solution B, mix it with solution A and stir in an oil bath at 100 °C for 6 h at a stirring speed of 350 rpm. After the oil bath is completed, wash the product with ethanol and place it in a vacuum drying oven at 60 °C for 12 h.

[0044] (3) The product obtained in step (2) was calcined at 400 °C in an argon atmosphere with a heating rate of 2 °C / min and a holding time of 3 h to obtain G@np-TiO2.

[0045] (4) The composite material obtained in step (3) was mixed with sulfur at a mass ratio of 1:3 and milled. The mixture was heated to 155 °C and kept at that temperature for 12 h in a polytetrafluoroethylene reactor. G@np-TiO2 / S was obtained by melt diffusion method.

[0046] (5) G@np-TiO2 / S obtained in step (4) is milled and mixed with conductive carbon black and polyvinylidene fluoride in a mass ratio of 8:1:1. N-methylpyrrolidone is added dropwise to adjust the solid content to 25% to prepare a positive electrode slurry. Then it is coated on an aluminum foil current collector, dried, pressed, and assembled into a CR2032 button cell in a glove box.

[0047] Example 4

[0048] The preparation methods of G@np-TiO2 lithium-sulfur battery cathode support material and lithium-sulfur battery are as follows:

[0049] (1) 1.5 g of triblock copolymer Pluronic F127 was added to 30 mL of tetrahydrofuran, acetic acid and hydrochloric acid were added dropwise to the solution, and finally 3 mL of tetrabutyl titanate was added dropwise to form a golden yellow solution. The solution was stirred evenly and placed in an oven at 50 °C for 16 h to evaporate and obtain a yellowish-white titanium dioxide single micelle gel. The acetic acid was anhydrous acetic acid and the hydrochloric acid was concentrated hydrochloric acid.

[0050] (2) Take 1.5 g of titanium gel obtained in step (1), dissolve it in 5 mL of anhydrous ethanol, add 3 mL of tetramethylbenzidine and 10 mL of glycerol, and stir to obtain solution A; disperse 50 mg of graphene in 10 mL of anhydrous ethanol to obtain solution B, mix it with solution A and stir in an oil bath at 80 °C for 6 h at a stirring speed of 400 rpm. After the oil bath is completed, wash the product with ethanol and place it in a vacuum drying oven at 60 °C for 12 h.

[0051] (3) The product obtained in step (2) was calcined at 350 °C in an argon atmosphere with a heating rate of 2 °C / min and a holding time of 4 h to obtain G@np-TiO2.

[0052] (4) The composite material obtained in step (3) was mixed with sulfur at a mass ratio of 1:4 and milled. The mixture was heated to 155 °C and kept at that temperature for 12 h in a polytetrafluoroethylene reactor. G@np-TiO2 / S was obtained by melt diffusion method.

[0053] (5) G@np-TiO2 / S obtained in step (4) is milled and mixed with conductive carbon black and polyvinylidene fluoride in a mass ratio of 8:1:1. N-methylpyrrolidone is added dropwise to adjust the solid content to 25% to prepare a positive electrode slurry. Then it is coated on an aluminum foil current collector, dried, pressed, and assembled into a CR2032 button cell in a glove box.

[0054] Example 5

[0055] The preparation methods of G@np-TiO2 lithium-sulfur battery cathode support material and lithium-sulfur battery are as follows:

[0056] (1) 1.5 g of triblock copolymer Pluronic F127 was added to 30 mL of tetrahydrofuran, acetic acid and hydrochloric acid were added dropwise to the solution, and finally 3 mL of tetrabutyl titanate was added dropwise to form a golden yellow solution. The solution was stirred evenly and placed in an oven at 50 °C for 16 h to evaporate and obtain a yellowish-white titanium dioxide single micelle gel. The acetic acid was anhydrous acetic acid and the hydrochloric acid was concentrated hydrochloric acid.

[0057] (2) Take 2 g of the titanium gel obtained in step (1), dissolve it in 5 mL of anhydrous ethanol, add 3 mL of tetramethylbenzidine and 10 mL of glycerol, and stir to obtain solution A; disperse 50 mg of graphene in 10 mL of anhydrous ethanol to obtain solution B, mix and stir with solution A, and stir in an oil bath at 120 °C for 4 h at a stirring speed of 300 rpm. After the oil bath is completed, wash the product with ethanol and place it in a vacuum drying oven at 60 °C for 12 h.

[0058] (3) The product obtained in step (2) was calcined at 350 °C in an argon atmosphere with a heating rate of 2 °C / min and a holding time of 4 h to obtain G@np-TiO2.

[0059] (4) The composite material obtained in step (3) was mixed with sulfur at a mass ratio of 1:4 and milled. The mixture was heated to 155 °C and kept at that temperature for 12 h in a polytetrafluoroethylene reactor. G@np-TiO2 / S was obtained by melt diffusion method.

[0060] (5) G@np-TiO2 / S obtained in step (4) is milled and mixed with conductive carbon black and polyvinylidene fluoride in a mass ratio of 8:1:1. N-methylpyrrolidone is added dropwise to adjust the solid content to 25% to prepare a positive electrode slurry. Then it is coated on an aluminum foil current collector, dried, pressed, and assembled into a CR2032 button cell in a glove box.

[0061] Example 6

[0062] The preparation methods of G@np-TiO2 lithium-sulfur battery cathode support material and lithium-sulfur battery are as follows:

[0063] (1) 1.5 g of triblock copolymer Pluronic F127 was added to 30 mL of tetrahydrofuran, acetic acid and hydrochloric acid were added dropwise to the solution, and finally 3 mL of tetrabutyl titanate was added dropwise to form a golden yellow solution. The solution was stirred evenly and placed in an oven at 50 °C for 16 h to evaporate and obtain a yellowish-white titanium dioxide single micelle gel. The acetic acid was anhydrous acetic acid and the hydrochloric acid was concentrated hydrochloric acid.

[0064] (2) Take 3 g of the titanium gel obtained in step (1), dissolve it in 5 mL of anhydrous ethanol, add 3 mL of tetramethylbenzidine and 10 mL of glycerol, and stir to obtain solution A; disperse 50 mg of graphene in 10 mL of anhydrous ethanol to obtain solution B, mix and stir with solution A, and stir in an oil bath at 120 °C for 4 h at a stirring speed of 300 rpm. After the oil bath is completed, wash the product with ethanol and place it in a vacuum drying oven at 60 °C for 12 h.

[0065] (3) The product obtained in step (2) was calcined at 350 °C in an argon atmosphere with a heating rate of 2 °C / min and a holding time of 4 h to obtain G@np-TiO2.

[0066] (4) The composite material obtained in step (3) was mixed with sulfur at a mass ratio of 1:4 and milled. The mixture was heated to 155 °C and kept at that temperature for 12 h in a polytetrafluoroethylene reactor. G@np-TiO2 / S was obtained by melt diffusion method.

[0067] (5) G@np-TiO2 / S obtained in step (4) is milled and mixed with conductive carbon black and polyvinylidene fluoride in a mass ratio of 8:1:1. N-methylpyrrolidone is added dropwise to adjust the solid content to 25% to prepare a positive electrode slurry. Then it is coated on an aluminum foil current collector, dried, pressed, and assembled into a CR2032 button cell in a glove box.

[0068] Comparative Example 1

[0069] A commercial lithium-sulfur battery cathode material and a method for preparing a lithium-sulfur battery are as follows:

[0070] Commercial carbon material acetylene black was mixed with sulfur at a mass ratio of 1:4 and milled. The mixture was then heated to 155 °C and held for 12 h in a polytetrafluoroethylene reactor to obtain an acetylene black / sulfur composite material via melt diffusion. The composite material was milled and mixed with conductive carbon black and polyvinylidene fluoride at a mass ratio of 8:1:1. N-methylpyrrolidone was added dropwise to adjust the solid content to 25% to prepare a positive electrode slurry. This slurry was then coated onto an aluminum foil current collector, dried, pressed, and assembled into a CR2032 coin cell in a glove box. This preparation method is consistent with the positive electrode material preparation method in the examples, except that commercial carbon material acetylene black was used as the positive electrode material.

[0071] Figure 1 The X-ray diffraction pattern of G@np-TiO2 in Example 1 is shown below. Comparison with the standard diffraction pattern of TiO2 shows that after high-temperature calcination, the crystal form of TiO2 in G@np-TiO2 is anatase. The diffraction peaks at 2θ of 25.3°, 38.0°, 48.2°, 54.2°, 62.6°, 69.0° and 75.2° correspond to the (1 0 1), (0 0 4), (2 0 0), (1 0 5), (2 0 4), (1 1 6) and (2 1 5) crystal planes of TiO2, respectively.

[0072] Figure 2 The image shown is a transmission electron microscope (TEM) image of G@np-TiO2 from Example 1. It can be seen that nanoporous TiO2 was successfully loaded onto graphene. The nanopores are uniformly distributed across the entire surface and have a very high density. The pore size is relatively uniform and concentrated at 4.0 nm.

[0073] Figure 3 The nitrogen isotherm adsorption-desorption curve of the graphene-supported titanium dioxide composite material in Example 1 shows that the material belongs to the type IV isotherm and has a hysteresis loop under high relative pressure, indicating that the material has a mesoporous structure with pore size mainly distributed around 4.0 nm.

[0074] Figure 4 The first charge-discharge curve of G@np-TiO2 / S in Example 1 at room temperature and a current density of 0.05 C is shown. The first discharge plateau is around 2.35 V. This process involves the reaction of elemental sulfur with lithium to form long-chain lithium polysulfides, and the transition of long-chain lithium polysulfides to short-chain lithium polysulfides corresponds to the second discharge plateau at 2.10 V. Its discharge specific capacity reaches 1340 mAh·g. -1 The active substance sulfur was well utilized.

[0075] Figure 5The graphene / titanium dioxide / sulfur composite material of Example 1 and the acetylene black / sulfur composite material of Comparative Example 1 were tested for cycling performance at room temperature and a current density of 0.5 C. The graphene / titanium dioxide / sulfur composite material exhibited an initial discharge specific capacity of 827 mAh·g. -1 After 100 cycles, the discharge specific capacity is 758.7 mAh·g. -1 The capacity retention rate reached 91.74%, and the capacity decay per cycle was 0.083%. Compared with the acetylene black / sulfur composite material, its initial discharge specific capacity was only 610.8 mAh·g. -1 Compared with the reported TiO2-based cathode materials, G@np-TiO2 / S effectively improves the discharge specific capacity of lithium-sulfur batteries while ensuring cycle performance.

[0076] The above preferred embodiments are merely technical solutions of the present invention and should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make changes in form and detail, but these changes should not deviate from the scope defined by the claims of the present invention.

Claims

1. A method for preparing graphene-supported nanoporous titanium dioxide lithium-sulfur battery cathode carrier material, characterized in that, Includes the following steps: (1) Add the triblock copolymer Pluronic F127 to tetrahydrofuran, add acetic acid and hydrochloric acid dropwise to the solution, and then add tetrabutyl titanate dropwise to form a golden yellow solution. Stir evenly and place in an oven to evaporate to obtain titanium dioxide single micelle gel. (2) Take the titanium dioxide single micelle gel obtained in step (1), dissolve it in anhydrous ethanol, add tetramethylbenzidine and glycerol, and stir to obtain solution A; Graphene was ultrasonically dispersed in anhydrous ethanol to obtain solution B. Solution B was then uniformly mixed with solution A and stirred in an oil bath. After completion, the product was washed and dried. (3) The product obtained in step (2) is calcined at high temperature in an inert gas atmosphere to obtain graphene-supported nanoporous titanium dioxide lithium-sulfur battery cathode carrier material. In step (1), the mass ratio of the triblock copolymer Pluronic F127 to the volume ratio of tetrahydrofuran is 1-2 g: 10-30 mL, the volume fraction of the tetrabutyl titanate is 3-10%, the acetic acid is anhydrous acetic acid, and the hydrochloric acid is concentrated hydrochloric acid; the evaporation temperature of the oven is 30-50 ℃, and the time is 16-48 h. In step (2), the graphene is raw graphene and does not require secondary processing. The volume fraction of glycerol in solution A is 20-60%, and the concentration of graphene in solution B is 2-5 mg / mL. In step (3), the calcination temperature is 350-400 ℃, the heating rate is 2-5 ℃ / min, and the holding time is 2-5h.

2. The method for preparing the graphene-supported nanoporous titanium dioxide lithium-sulfur battery cathode carrier material according to claim 1, characterized in that, In step (2), the temperature of the oil bath is 80-120 ℃, the stirring speed is 300-400 rpm, the time is 3-6 h, the washing solvent is ethanol, and the drying conditions are vacuum drying at 30-60 ℃ for 12-24 h.

3. A graphene-supported nanoporous titanium dioxide lithium-sulfur battery cathode carrier material, characterized in that, It is prepared by the preparation method according to any one of claims 1-2.

4. The graphene-supported nanoporous titanium dioxide lithium-sulfur battery cathode carrier material according to claim 3, characterized in that, The titanium dioxide is in situ loaded on the graphene surface to form a nanoporous structure with a pore size of 2-10 nm.

5. A lithium-sulfur battery, characterized in that, It is prepared using the graphene-supported nanoporous titanium dioxide lithium-sulfur battery cathode carrier material as described in any one of claims 3 or 4.

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