Preparation method of a phosphinyl dysprosium complex composite carbon two-dimensional material and application thereof in lithium-sulfur batteries

Abstract

The application discloses a preparation method of a two-dimensional material of a phosphinyl dysprosium complex composite carbon and application of the two-dimensional material in a lithium-sulfur battery, and a structural formula of the two-dimensional material is CNT@[(dppBO2)DyCl3(mu-dppBO2)DyCl3(dppBO2)] n The two-dimensional material of the rare earth complex composite carbon is prepared by selecting carbon materials and a phosphinyl dysprosium complex, the f orbit of the phosphinyl dysprosium complex can control the electronic transmission path of a catalytic interface, the reaction kinetics is enhanced, and the electronic conductivity of the two-dimensional material is improved. Meanwhile, the two-dimensional material has the advantages of good stability, high catalytic activity, excellent discharge performance and good cycle performance, and can be used as a polysulfide redox material, and has a wide application prospect in the fields of lithium-sulfur batteries, fuel cells, electrochemical sensors and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material preparation, in particular to a preparation method of a phosphinyl dysprosium complex composite carbon two-dimensional material and its application in lithium-sulfur batteries. BACKGROUND

[0002] The redox reaction of polysulfides has important significance in many fields, such as lithium-sulfur batteries, fuel cells, electrochemical sensors, etc. However, the redox reaction kinetics of polysulfides is slow, which seriously restricts the performance of related devices. Therefore, it is of great significance to develop efficient and stable polysulfide redox reaction catalysts. Carbon nanotube two-dimensional materials have excellent electrical conductivity, large specific surface area and rich surface chemical properties, and are ideal catalyst carriers. Rare earth metal complexes, especially dysprosium complexes, have unique electronic structure and coordination ability, and show good catalytic activity in polysulfide redox reactions.

[0003] Lithium-sulfur batteries are considered as the next generation of high-energy energy storage devices due to their high theoretical specific capacity and energy density. However, the "shuttle effect" of polysulfides leads to active material loss and capacity decay, which seriously limits its commercialization. Currently, carbon-based materials such as carbon nanotubes (CNT), graphene, etc. can physically adsorb polysulfides, but lack catalytic activity for redox reactions; transition metal compounds can catalyze the conversion of polysulfides, but have poor electrical conductivity and insufficient stability. Rare earth complexes have potential in multi-electron catalysis due to their unique electronic structure and coordination ability, but the compounding of their one-dimensional chain structure with two-dimensional conductive substrates has not been fully studied. SUMMARY

[0004] In order to overcome the above-mentioned defects and shortcomings in the prior art, the present application provides a preparation method of a phosphinyl dysprosium complex composite carbon two-dimensional material and its application in lithium-sulfur batteries.

[0005] The first object of the present application is to provide a dysprosium complex.

[0006] The second object of the present application is to provide a preparation method of the dysprosium complex.

[0007] The third object of the present application is to provide the application of the dysprosium complex in the preparation of a polysulfide redox catalyst.

[0008] The fourth object of the present application is to provide a composite material.

[0009] The fifth object of the present application is to provide a preparation method of a composite material.

[0010] The sixth object of the present application is to provide a composite material prepared by the above-mentioned preparation method.

[0011] A seventh object of the present application is to provide the use of the above-mentioned composite material in catalyzing the redox of polysulfides.

[0012] An eighth object of the present application is to provide the use of the above-mentioned composite material in preparing lithium-sulfur battery electrode.

[0013] The present application claims the following:

[0014] A dysprosium complex, the structural formula of which is [(dppBO2)DyCl3(μ-dppBO2)DyCl3(dppBO2)] n , wherein dppBO2 is 1,4-butandiylbis(diphenylphosphine oxide);

[0015] The dysprosium complex crystallizes in trigonal system, belongs to R-3 space group, and has the following cell parameters: α = 90°, β = 90°, γ = 120°,

[0016] The preparation method of the above-mentioned dysprosium complex is as follows: an ethanol solution of dppBO2 and DyCl3·6H2O are fully reacted at 130-150°C for 72-74h, and then cooled at a rate lower than 5°C / h.

[0017] Preferably, the use amount ratio of dppBO2, ethanol and DyCl3·6H2O is (0.8-1.2) mmol:(3.2-4.8) mL:(0.8-1.2) mmol.

[0018] More preferably, the use amount ratio of dppBO2, ethanol and DyCl3·6H2O is 1 mmol:4 mL:1 mmol.

[0019] More preferably, the reaction temperature is 140°C.

[0020] More preferably, the reaction time is 72h.

[0021] More preferably, the cooling rate is 2°C / h.

[0022] More preferably, the cooling is to 24-26°C.

[0023] The use of the above-mentioned dysprosium complex in preparing polysulfide redox catalyst.

[0024] A composite material, which comprises the above-mentioned dysprosium complex and carbon material, the dysprosium complex being dispersed in the conductive network formed by the carbon material and forming a crosslinked structure.

[0025] The carbon material includes carbon nanotubes, graphite, carbon fibers and graphene.

[0026] A preparation method of a composite material, the preparation method being: after carbon material and dppBO2 are fully mixed with ethanol, DyCl3 6H2O is added, and the mixture is fully reacted at 130-150 DEG C for 72-74 h, and then the temperature is lowered at a rate of less than 5 DEG C / h, and the composite material is obtained.

[0027] The carbon material includes carbon nanotubes, graphite, carbon fibers and graphene.

[0028] Preferably, the carbon material is carbon nanotubes.

[0029] More preferably, the use amount ratio of the carbon nanotubes, dppBO2, ethanol and DyCl3 6H2O is (28-32) mmol:(0.8-1.2) mmol:(3.2-4.8) mL:(0.8-1.2) mmol.

[0030] Further preferably, the use amount ratio of the carbon nanotubes, dppBO2, ethanol and DyCl3 6H2O is 30 mmol:1 mmol:4 mL:1 mmol.

[0031] More preferably, the reaction temperature is 140 DEG C.

[0032] More preferably, the reaction time is 72 h.

[0033] More preferably, the temperature lowering rate is 2 DEG C / h.

[0034] More preferably, the temperature lowering is to 24-26 DEG C.

[0035] The composite material prepared by the preparation method.

[0036] The composite material is applied to catalyze polysulfide redox.

[0037] The composite material is applied to prepare a lithium-sulfur battery electrode.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] The present application discloses a preparation method of a diphosphine oxide dysprosium complex composite carbon two-dimensional material and application of the two-dimensional material in a lithium-sulfur battery. n The present application selects carbon material and diphosphine oxide dysprosium complex [(dppBO2)DyCl3(μ-dppBO2)DyCl3(dppBO2)] nA two-dimensional material composed of a rare earth complex and carbon has been prepared. The f orbitals in the phosphinyl dysprosium complex can regulate the electron transport pathways at the catalytic interface, enhancing reaction kinetics and improving the electronic conductivity of the two-dimensional material. Furthermore, the two-dimensional material of the present invention exhibits advantages such as good stability, high catalytic activity, excellent discharge performance, large specific surface area, abundant active sites, and good cycling performance. It can be used as a polysulfide redox material. Through the synergistic effect of the one-dimensional chain-like rare earth complex and the carbon two-dimensional material, it addresses the problems of slow polysulfide redox kinetics and the shuttle effect. This material has broad application prospects in lithium-sulfur batteries, fuel cells, electrochemical sensors, and other fields.

[0040] In addition, the preparation method of the two-dimensional material composited with the phosphine oxide-based dysprosium complex of the present invention is simple and low-cost. The preparation of composite functional materials with high yield and high crystallinity can be achieved through low-temperature solvent thermal reaction, which meets the requirements of green chemistry and is suitable for large-scale mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Single crystal structure of the phosphine-based dysprosium complex prepared in Example 1; (a) minimum asymmetric unit, (b) unit cell structure, (c) two-dimensional layered stacking of the complex; (d) central dysprosium ion in a hexacoordinate octahedral configuration. H atoms are omitted in all structural diagrams for clarity and simplicity.

[0042] Figure 2 These are infrared spectra of the phosphinyl dysprosium complex prepared in Example 1 and the composite material prepared in Example 2, wherein 1 is the phosphinyl dysprosium complex and 2 is the composite material.

[0043] Figure 3 These are Raman spectra of the phosphinyl dysprosium complex prepared in Example 1 and the composite material prepared in Example 2, wherein 1 is the phosphinyl dysprosium complex and 2 is the composite material.

[0044] Figure 4 These are thermogravimetric curves of the phosphinyl dysprosium complex prepared in Example 1 and the composite material prepared in Example 2, wherein 1 is the phosphinyl dysprosium complex and 2 is the composite material.

[0045] Figure 5 These are the X-ray powder diffraction patterns of the phosphinyl dysprosium complex prepared in Example 1 and the composite material prepared in Example 2, where 1synthesized is the diffraction spectrum of the phosphinyl complex obtained based on single crystal testing, 2synthesized is the diffraction spectrum of the composite material obtained based on single crystal testing, and 1simulated is the theoretical diffraction spectrum of the phosphinyl complex simulated based on single crystal testing.

[0046] Figure 6Scanning electron microscope images of the phosphinyl dysprosium complex prepared in Example 1 and the composite material prepared in Example 2; (a): phosphinyl dysprosium complex magnified 20000 times, (b): phosphinyl dysprosium complex magnified 50000 times, (c): composite material magnified 20000 times, (d): composite material magnified 110000 times.

[0047] Figure 7 Transmission electron microscope images of the phosphinyl dysprosium complex prepared in Example 1 and the composite material prepared in Example 2; (a): transmission electron microscope image of the phosphinyl dysprosium complex, (b): energy dispersive spectroscopy image of the phosphinyl dysprosium complex in the plane scanning mode; (c): transmission electron microscope image of the composite material, (d): energy dispersive spectroscopy image of the composite material in the plane scanning mode.

[0048] Figure 8 X-ray photoelectron spectrograms of the phosphinyl dysprosium complex prepared in Example 1 and the composite material prepared in Example 2; (a): phosphinyl dysprosium complex, (b): composite material.

[0049] Figure 9 is a comparison of discharge capacity of pure carbon nanotubes and the composite material prepared in Example 2 at different currents.

[0050] Figure 10 is a long cycle performance diagram of electrodes of pure carbon nanotubes and the composite material prepared in Example 2 at 0.5C current. DETAILED DESCRIPTION

[0051] The present application will be further described in conjunction with specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field.

[0052] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0053] The structural formula of dppBO2 used in the examples is shown in formula (I), wherein n = 4, which is dppBO2 in Chinese invention patent CN118745199A.

[0054]

[0055] Preparation of phosphinyl dysprosium complex in Example 1

[0056] Take 0.0568g dppBO2 in a polytetrafluoroethylene reactor, add 4mL ethanol, stir for 10min at 25℃, then add 0.0545g DyCl3·6H2O, continue to stir for 10min, then carry out solvothermal reaction. The reaction conditions are as follows: 5h to 140℃, then constant temperature reaction for 72h, then decrease to 25℃ at a rate of 2℃ / h to obtain colorless block crystal, which is phosphinyl dysprosium complex [(dppBO2)DyCl3(μ-dppBO2)DyCl3(dppBO2)] n .

[0057] Preparation of composite material of example 2

[0058] Take 25mg carbon nanotubes and 0.0568g dppBO2 in a polytetrafluoroethylene reactor, add 4mL ethanol, stir for 10min at 25℃, then add 0.0545g DyCl3·6H2O, continue to stir for 10min, then carry out solvothermal reaction. The reaction conditions are as follows: 5h to 140℃, then constant temperature reaction for 72h, then decrease to 25℃ at a rate of 2℃ / h to obtain colorless block crystal, which is composite material CNT@[(dppBO2)DyCl3(μ-dppBO2)DyCl3(dppBO2)] n .

[0059] Crystal structure determination and characterization of example 3

[0060] I. Experimental method

[0061] Select the size of 0.095*0.093*0.072mm 3 colorless block single crystal product (prepared in example 1) for structure test, use Japan science XtaLAB Synergy R, DW system, HyPix single crystal X-ray diffractometer to diffract at 298.15K temperature, graphite monochromator monochromatized CuKα ray as incident light source to collect diffraction data and process. All calculations use SHELXS-2014 and SHELXL-2014 programs.

[0062] Respectively, the phosphinyl dysprosium complex prepared in example 1 and the composite material prepared in example 2 are tested by infrared spectrum, Raman spectrum, thermogravimetric analysis, scanning electron microscope and transmission electron microscope, and the phosphinyl dysprosium complex and the composite material are placed in air for 3 months and then tested by X-ray powder diffraction.

[0063] II. Experimental results

[0064] Single crystal structure analysis shows that the phosphine-based dysprosium complex prepared in Example 1 (referred to as Complex 1 in Table 1) belongs to the trigonal crystal system, the space group is R-3, and the unit cell parameters are: α=90°, β=90°, γ=120°, The crystallographic data are shown in Table 1.

[0065] Table 1 Crystallographic data and refinement results of phosphine-based dysprosium complexes

[0066]

[0067]

[0068] Depend on Figure 1 From (a) to (d) in Example 1, it can be seen that the asymmetric unit of the phosphine-based dysprosium complex prepared in Example 1 includes a Dy III , half of the phosphine ligand and a coordinated chloride ion, with no external crystallization solvent. The central metal ion dysprosium ion forms a hexacoordinated octahedral geometry (O h ), because the three oxygen atoms come from different phosphine ligands, they extend in the plane to form a two-dimensional layered structure. The closest Dy-Dy distance within the molecule is The CShM value of the central Dy(III) ion calculated using Shape software is 0.93697 (Table 2). The average Dy-O and Dy-Cl bond lengths are and Because of symmetry, the three Dy-O and three Dy-Cl bond lengths are equal.

[0069] Table 2 CShM values ​​of the central Dy(III) ion in phosphinyl dysprosium complex (complex 1)

[0070]

[0071] *HP-6 = hexagon, PPY-6 = pentagonal pyramid, OC-6 = octahedron, TPR-6 = triangular prism, JPPY-6 = Johnson pentagonal pyramid J2.

[0072] The infrared spectra of the phosphine-based dysprosium complex prepared in Example 1 and the composite material prepared in Example 2 are shown in FIG. Figure 2 As shown. Figure 2 It can be seen that the phosphine-based dysprosium complex has a peak at 1597 cm -1 Obvious characteristic peaks of benzene ring can be observed at 900~650cm -1The out-of-plane deformation vibration of C-H on the aromatic ring appears in the region. Compared with the phosphine oxide ligand, the absorption peaks of some functional groups of the phosphine oxide dysprosium complex and the composite material are obviously red-shifted, and the intensity is also changed to a certain extent, which indicates that the organic ligand 1,4-butyl bis(diphenyl phosphine oxide) participates in the coordination.

[0073] The Raman spectra of the phosphine oxide dysprosium complex prepared in Example 1 and the composite material prepared in Example 2 are shown in Figure 3 From Figure 3 , it can be seen that the composite material has a disorder peak (D peak) at 1341 cm -1 in the medium frequency region under the excitation wavelength of 532 nm, which is a disorder peak of the boundary vibration mode of the disordered hexagonal Brillouin zone, and is derived from the stretching vibration of C-C bond and C=C double bond, and is a typical Raman peak in carbon materials such as carbon nanotubes and graphene. -1 An obvious G peak appears, which is caused by the vibration of sp 2 carbon atom in the carbon nanotube, and reflects the graphitization characteristics of the carbon nanotube. The 2D peak appears at about 2686 cm -1 , which is caused by the van der Waals force between the carbon nanotube layers, and is obviously blue-shifted compared with the pure carbon tube, which indicates that the phosphine oxide dysprosium complex has an effect on the carbon nanotube. For the phosphine oxide dysprosium complex, a single peak caused by the double bond of the aromatic hydrocarbon molecule can be observed at 1587 cm -1 , and the absorption peak of the low-frequency C-H appears at 3060 cm -1 , which is obviously blue-shifted compared with the ligand, indicating that the intermolecular interaction is enhanced after the formation of the phosphine oxide dysprosium complex.

[0074] The thermogravimetric diagrams of the phosphine oxide dysprosium complex prepared in Example 1 and the composite material prepared in Example 2 are shown in Figure 4 From Figure 4 , it can be seen that the thermal stability of the phosphine oxide dysprosium complex and the composite material is very high, and the weight loss and structural destruction decomposition phenomenon begin to appear above 350 DEG C.

[0075] The X-ray powder diffraction test results of the phosphine oxide dysprosium complex prepared in Example 1 and the composite material prepared in Example 2 after being placed in air for 3 months are shown in Figure 5 From Figure 5 , it can be seen that the peak position, peak shape and peak intensity of the test peak obtained after single crystal test and the simulation peak are basically consistent, which indicates that the phosphine oxide dysprosium complex and the composite material have good stability, can be stored in air for a long time, and have good crystallinity.

[0076] The scanning electron microscope images of the phosphine oxide dysprosium complex prepared in Example 1 and the composite material prepared in Example 2 are shown in Figure 6The TEM and EDS images of the phosphinyl dysprosium complex prepared in Example 1 and the composite prepared in Example 2 are shown in (a) and (b) of FIG. 1, and the photoelectron spectrum is shown in (a) and (b) of FIG. 2, and the element content is shown in Table 3. It can be seen from FIG. 1 and Table 3 that the phosphinyl dysprosium complex has a layered structure, and the composite has a cross-linked structure, and the layered complex is dispersed in the carbon nanotubes. Figure 6 The TEM and EDS images of the phosphinyl dysprosium complex prepared in Example 1 and the composite prepared in Example 2 are shown in (a) and (b) of FIG. 1, and the photoelectron spectrum is shown in (a) and (b) of FIG. 2, and the element content is shown in Table 3. It can be seen from FIG. 1 and Table 3 that the phosphinyl dysprosium complex has a layered structure, and the composite has a cross-linked structure, and the layered complex is dispersed in the carbon nanotubes.

[0077] The TEM and EDS images of the phosphinyl dysprosium complex prepared in Example 1 and the composite prepared in Example 2 are shown in (a) and (b) of FIG. 1, and the photoelectron spectrum is shown in (a) and (b) of FIG. 2, and the element content is shown in Table 3. It can be seen from FIG. 1 and Table 3 that the phosphinyl dysprosium complex has a layered structure, and the composite has a cross-linked structure, and the layered complex is dispersed in the carbon nanotubes. Figure 7 The TEM and EDS images of the phosphinyl dysprosium complex prepared in Example 1 and the composite prepared in Example 2 are shown in (a) and (b) of FIG. 1, and the photoelectron spectrum is shown in (a) and (b) of FIG. 2, and the element content is shown in Table 3. It can be seen from FIG. 1 and Table 3 that the phosphinyl dysprosium complex has a layered structure, and the composite has a cross-linked structure, and the layered complex is dispersed in the carbon nanotubes. Figure 8 The TEM and EDS images of the phosphinyl dysprosium complex prepared in Example 1 and the composite prepared in Example 2 are shown in (a) and (b) of FIG. 1, and the photoelectron spectrum is shown in (a) and (b) of FIG. 2, and the element content is shown in Table 3. It can be seen from FIG. 1 and Table 3 that the phosphinyl dysprosium complex has a layered structure, and the composite has a cross-linked structure, and the layered complex is dispersed in the carbon nanotubes. Figure 8 The TEM and EDS images of the phosphinyl dysprosium complex prepared in Example 1 and the composite prepared in Example 2 are shown in (a) and (b) of FIG. 1, and the photoelectron spectrum is shown in (a) and (b) of FIG. 2, and the element content is shown in Table 3. It can be seen from FIG. 1 and Table 3 that the phosphinyl dysprosium complex has a layered structure, and the composite has a cross-linked structure, and the layered complex is dispersed in the carbon nanotubes.

[0078] Table 3 Element content

[0079]

[0080]

[0081] Comparative Example 1

[0082] I. Experimental method

[0083] The dysprosium complex was synthesized according to the method of Example 1, except that the reaction temperature was adjusted to be below 130°C.

[0084] II. Experimental results

[0085] The product was a powdery solid, and the complex crystals were not crystallized.

[0086] Comparative Example 2

[0087] I. Experimental method

[0088] The dysprosium complex was synthesized according to the method of Example 1, except that the constant temperature reaction time was set to be less than 72h.

[0089] II. Experimental results

[0090] The product was a powdery solid precipitate or very small crystals, and could not be subjected to structure determination.

[0091] Comparative Example 3

[0092] I. Experimental method

[0093] The dysprosium complex was synthesized according to the method of Example 1, except that the cooling rate was set to 5°C / min or more.

[0094] II. Experimental Results

[0095] The product was a powdery solid, and the complex crystals were not crystallized.

[0096] Comparative Example 4

[0097] I. Experimental Methods

[0098] The dysprosium complex was synthesized according to the method of Example 1, except that ethanol was replaced with methanol, acetonitrile, or water.

[0099] II. Experimental Results

[0100] The product was a powdery solid precipitate or microcrystalline, and structural determination was not possible.

[0101] Comparative Example 5

[0102] I. Experimental Methods

[0103] The dysprosium complex was synthesized according to the method of Example 1, except that the reaction temperature was adjusted to 150°C or more.

[0104] II. Experimental Results

[0105] The crystal growth rate was too fast, and the product was an amorphous powdery solid precipitate with large and uneven particles, and structural determination was not possible.

[0106] Comparative Example 6

[0107] I. Experimental Methods

[0108] The composite material was synthesized according to the method of Example 2, except that the reaction temperature was adjusted to 130°C or less.

[0109] II. Experimental Results

[0110] The product was a black-doped white powdery solid with large and uneven particles.

[0111] Comparative Example 7

[0112] I. Experimental Methods

[0113] The composite material was synthesized according to the method of Example 2, except that the reaction time was set to less than 72 h.

[0114] II. Experimental Results

[0115] The product was a black-doped white microcrystalline powdery solid with large and uneven particles.

[0116] Comparative Example 8

[0117] I. Experimental method

[0118] The composite material was synthesized according to the method of Example 2, except that the cooling rate was set to 5℃ / min or above.

[0119] II. Experimental results

[0120] The product was a black-doped white microcrystalline powder solid, with large and uneven particles.

[0121] Comparative Example 9

[0122] I. Experimental method

[0123] The composite material was synthesized according to the method of Example 2, except that ethanol was replaced by methanol, acetonitrile or water.

[0124] II. Experimental results

[0125] The product was a black-doped white powder solid without crystallinity.

[0126] Comparative Example 10

[0127] I. Experimental method

[0128] The composite material was synthesized according to the method of Example 2, except that the reaction temperature was adjusted to 150℃ or above.

[0129] II. Experimental results

[0130] The crystal growth rate was too fast to form defects, and the product was a black amorphous powder solid precipitate, with large and uneven particles.

[0131] As can be seen by comparing Examples 1-2 and Comparative Examples 1-10, the preparation of the phosphinyl dysprosium complex and composite material of the present application requires a solvothermal reaction at a reaction temperature of 130-150℃ for 72h using ethanol as the solvent, and the cooling rate should be slow, so that the final product can be crystallized with a suitable solubility, thereby obtaining the target product with excellent quality and high purity.

[0132] Electrochemical test of Example 4

[0133] Preparation of sulfur-carbon composite material: 0.09g of the composite material CNT@[(dppBO2)DyCl3(μ-dppBO2)DyCl3(dppBO2)] prepared in Example 2 was taken and mixed with 0.21g of commercial sublimed sulfur by grinding for 50min, and then placed in a reaction kettle and heated at 155℃ for 12h to obtain a sulfur-carbon composite material. n As a sulfur carrier, after being mixed and ground with 0.21g of commercial sublimed sulfur for 50min, it was placed in a reaction kettle and heated at 155℃ for 12h to obtain a sulfur-carbon composite material.

[0134] Electrode preparation: 0.21 g of sulfur-carbon composite material, 0.06 g of conductive carbon black and 0.03 g of polyvinylidene fluoride (PVDF) were prepared into a uniform slurry by 12 h magnetic stirring in N-methyl pyrrolidone (NMP). The prepared slurry was evenly coated on an aluminum foil and transferred to a 50℃ vacuum drying oven to dry the solvent, thereby obtaining an electrode.

[0135] The prepared electrode was used as a positive electrode, and metal lithium was used as a negative electrode; LiNO3 and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were dissolved in a solution mixed by 1,3-dioxolane and ethylene glycol dimethyl ether at a volume ratio of 1:1 as an electrolyte, so that the mass fraction of LiNO3 in the electrolyte was 2%, and the concentration of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was 1 mol / L; a commercial Celegard 2400 polymer porous film was used as a separator, and a button cell was assembled in an inert atmosphere glove box.

[0136] Through a blue cell test system, the charge-discharge capacity of the sulfur-carbon composite material under different currents (0.2, 0.5, 1.0, 2.0C) and the cycle stability under a 0.5C current were tested by changing the input current value in a voltage range of 1.7-2.8V.

[0137] II. Experimental results

[0138] Compared with pure carbon nanotubes as a sulfur carrier material, the composite material prepared in Example 2 as a sulfur carrier can significantly improve the rate performance ( Figure 9 ) and cycle stability ( Figure 10 ). The capacity retention rate of pure carbon nanotubes is less than 30% after 350 cycles, while the capacity retention rate of the composite material after being combined with the phosphinyl dysprosium complex is increased by more than 2 times, and is more than 60%. Compared with pure carbon nanotubes, the current is increased from 0.2C to 2.0C, and the capacity is reduced from 800 mAh / g to about 350 mAh / g. The capacity of the composite material prepared in Example 2 is as high as 900 mAh / g when the current is 0.2C, and the capacity is 550 mAh / g when the current is increased to 2.0C, with a retention rate of 55%.

[0139] Overall, based on the above test results, it can be known that the composite material prepared in the application is a carbon nanotube composite two-dimensional dysprosium complex composite material, which has good stability and high catalytic activity, and can be used as a battery catalytic material. In terms of preparation method, the raw materials of the application are rich in selection, simple and easy to operate, and high yield and high crystallinity samples can be prepared by low-temperature solvothermal method, which meets the development needs of green chemistry. The dysprosium complex composite carbon nanomaterial has high application value in the field of new energy materials.

[0140] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A dysprosium complex, characterized in that, The structure formula of the dysprosium complex is [(dppBO2)DyCl3(μ-dppBO2)DyCl3(dppBO2)] n wherein dppBO2 is 1,4-butandiylbis(diphenylphosphine oxide); The dysprosium complex crystallizes in trigonal system, belongs to R-3 space group, and has a unit cell parameter of: α = 90°, β = 90°, γ = 120°, 2. The process for the preparation of the dysprosium complex as claimed in claim 1, wherein, The ethanol solution of dppB02 and DyCl36H2O are fully reacted at 130-150℃ for 72-74h, and then cooled at a rate of less than 5℃ / h to obtain the product.

3. The production method according to claim 2, characterized by, The use amount ratio of dppB02, ethanol and DyCl36H2O is (0.8-1.2)mmol:(3.2-4.8)mL:(0.8-1.2)mmol.

4. The use of the dysprosium complex of claim 1 in the preparation of polysulfide redox catalysts.

5. A composite material, characterized by, The composite material comprises the dysprosium complex of claim 1 and carbon material, and the dysprosium complex is dispersed in the conductive network formed by the carbon material and forms a crosslinked structure. The carbon material comprises carbon nanotubes, graphite, carbon fibers and graphene.

6. A method of producing a composite material, characterized by, The carbon material and dppB02 are fully mixed with ethanol, and then DyCl36H2O is added and fully reacted at 130-150℃ for 72-74h, and then cooled at a rate of less than 5℃ / h to obtain the product. The carbon material comprises carbon nanotubes, graphite, carbon fibers and graphene.

7. The preparation method according to claim 6, characterized in that The use amount ratio of the carbon material, dppB02, ethanol and DyCl36H2O is (28-32)mmol:(0.8-1.2)mmol:(3.2-4.8)mL:(0.8-1.2)mmol.

8. The composite material prepared by the preparation method of any one of claims 6-7.

9. The use of the composite material of claim 5 and / or the composite material of claim 8 in catalyzing polysulfide redox.

10. The use of the composite material of claim 5 and / or the composite material of claim 8 in the preparation of lithium-sulfur battery electrodes.

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