A layered polysulfide positive electrode material and its preparation method and application

Abstract

The present invention discloses a layered polysulfide positive electrode material, a preparation method and an application thereof. The chemical formula of the layered polysulfide is Nb3TiP2S 18 Se3, Nb3TiP2S 18 Se3 is obtained by the matrix material Nb4P2S 21 Ti and Se co-doping is performed, where Ti occupies the Nb site and Se occupies the S site. As a positive electrode material, Ti doping can stabilize Nb4P2S 21 The structure of Se doping can improve the conductivity. By mixing Nb or NbS2, Ti, P or P2S5 and S, Se as raw materials, reacting under vacuum and high temperature conditions to obtain Nb3TiP2S with nano-granular morphology. 18 Se3 positive electrode material, compared with the undoped sample Nb4P2S 21 , the prepared Nb3TiP2S 18 Se3 positive electrode material has better electrochemical performance.

Description

Technical Field

[0001] The present invention relates to the technical field of metal-sulfur primary battery positive electrode materials, and in particular to a layered polysulfide positive electrode material, a preparation method and an application thereof. Background Art

[0002] Na-S batteries have attracted widespread attention due to their low cost and high energy density. However, the practical application of Na-S batteries still faces the following challenges: First, the low conductivity and huge volume expansion of the S positive electrode lead to poor rate characteristics and severe capacity decay. Second, the shuttle effect of the discharge product sodium polysulfide (NaPSs) causes a large loss of active materials. To solve the above problems, the most common strategy is to composite S with carbon materials, including porous carbon spheres, micro / porous carbon nanofibers and three-dimensional porous carbon matrices. These materials can improve conductivity and provide large pore volume to accommodate S during charge / discharge. Although carbon materials have large specific surface area and high porosity, it is difficult to effectively inhibit the shuttle effect of NaPSs due to the poor physical adsorption between non-polar carbon and polar NaPSs.

[0003] Compared with physical adsorption, chemical reactions can more effectively anchor polar NaPSs and inhibit their migration between the cathode and cathode during electrochemical cycling. Polar nanostructured materials, including metal nanoparticles, sulfides, oxides, nitrides, and carbide modified hosts, have been shown to effectively bind polar NaPs and catalyze the conversion of NaPSs to Na2S. Among the many S carrier materials, transition metal disulfides (TMDs) have natural advantages due to their stable layered structure and excellent conductivity. However, the current application of TMDs in Na-S batteries is mainly based on composite materials. There are few NaPSs adsorption sites and weak chemical bonding, making it difficult to achieve efficient conversion of the S positive electrode. Therefore, it is crucial to design a single-phase S-based positive electrode material with a stable layered structure and strong NaPSs adsorption. Summary of the Invention

[0004] In view of the above technical problems, the first object of the present invention is to provide a layered polysulfide positive electrode material, the chemical formula of which is Nb3TiP2S 18 Se3, this material has [PS4] / [PSe4] structural elements and [NbS6] / [NbSe6] structural elements. The [PS4] / [PSe4] structural elements have strong PS / P-Se bonds, which can effectively anchor polysulfide NaPSs, thereby preventing capacity loss caused by polysulfide dissolution. The [NbS6] / [NbSe6] structural elements have a stable two-dimensional structure and excellent conductivity, which can effectively buffer the volume expansion caused by the conversion reaction and improve the cycle stability and rate performance.

[0005] The second object of the present invention is to provide a method for preparing a layered polysulfide positive electrode material, wherein Nb or NbS2, Ti, P or P2S5 and S, Se are mixed as raw materials and reacted under vacuum and high temperature conditions to generate layered polysulfide Nb3TiP2S having [PS4] / [PSe4] structural units and [NbS6] / [NbSe6] structural units. 18 Se3, the preparation method is simple.

[0006] The third object of the present invention is to provide an application of a layered polysulfide positive electrode material in a battery or a capacitor.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] A layered polysulfide positive electrode material, wherein the chemical formula of the layered polysulfide is Nb3TiP2S 18 Se3, the layered polysulfide microstructure is nano-granular, which can significantly reduce the migration path of sodium ions and provide abundant sodium storage active sites; Nb3TiP2S 18 Se3 is obtained by the matrix material Nb4P2S 21 Ti and Se co-doping is performed, where Ti occupies the Nb site and Se occupies the S site; as a positive electrode material, Ti doping can stabilize Nb4P2S 21 The structure of [PS4] / [PSe4] and Se doping can improve the conductivity. The positive electrode material has [PS4] / [PSe4] structural elements and [NbS6] / [NbSe6] structural elements. The [PS4] / [PSe4] structural elements have strong PS / P-Se bonds and can effectively anchor polysulfides, thereby preventing the capacity loss caused by the dissolution of polysulfides. The [NbS6] / [NbSe6] structural elements have a stable two-dimensional structure and excellent conductivity, which can effectively buffer the volume expansion caused by the conversion reaction and improve the cycle stability and rate performance. Compared with the undoped sample Nb4P2S 21 , the prepared Nb3TiP2S 18 Se3 positive electrode has better electrochemical performance.

[0009] Based on the same inventive concept, the present invention also provides a method for preparing a layered polysulfide positive electrode material, wherein Nb or NbS2, Ti, P or P2S5, and S, Se are selected as raw materials and mixed, and then reacted at 450-650°C in a vacuum to obtain the layered polysulfide positive electrode material. The reaction temperature is preferably 500-600°C, such as 500°C, 550°C, 580°C or 600°C. The pressure of the vacuum is preferably less than 10mPa. The reaction time is preferably 4-24h, and more preferably 4-12h, such as 4h, 6h, 10h or 12h. For sodium electrode materials, the smaller the particle size, the higher the specific surface area, the more active sites exposed by the sample, and the Na + The shorter the transport path, the better the reversible capacity and rate performance. Therefore, the reaction time should be shortened as much as possible to obtain a pure phase in order to obtain a nano-sized sample.

[0010] wherein the molar ratio of Nb, Ti, P, S, and Se is 3:1:2:16-18:3-5; or

[0011] The molar ratio of NbS2, Ti, P, S and Se is 3:1:2:10-12:3-5; or

[0012] The molar ratio of Nb, Ti, P2S5, S and Se is 3:1:1:11-13:3-5; or

[0013] The molar ratio of NbS2, Ti, P2S5, S and Se is 3:1:1:5-7:3-5.

[0014] More preferably, the molar ratio of the elemental Nb, Ti, P, S and Se is 3:1:2:18:4; or

[0015] The molar ratio of NbS2, Ti, P, S and Se is 3:1:2:12:4; or

[0016] The molar ratio of NbS2, Ti, P, S and Se is 3:1:2:11:4; or

[0017] The molar ratio of Nb, Ti, P2S5, S and Se is 3:1:1:13:4; or

[0018] The molar ratio of NbS2, Ti, P2S5, S and Se is 3:1:1:7:4; or

[0019] The molar ratio of NbS2, Ti, P2S5, S and Se is 3:1:1:5:4.

[0020] Preferably, after the raw materials are mixed, they are fully ground to make the raw materials uniformly mixed to obtain a mixed powder.

[0021] Further preferably, considering that the reaction is carried out at high temperature, the mixed powder is encapsulated in a pre-evacuated quartz tube before the reaction. Since the S raw material is converted into S vapor during the high-temperature reaction, the quartz tube may not be able to withstand the S vapor pressure, resulting in rupture of the tube wall and oxidation of the sample. Therefore, the filling ratio of the raw material in the quartz tube is 1 / 7-1 / 6.

[0022] Preferably, after the reaction is completed, the temperature is lowered to room temperature at a rate of 5-10°C / min. A slower rate of cooling is set to ensure uniform distribution of nanoparticles and improve electrochemical activity. According to conventional practice in the art, the room temperature is generally 20-35°C, preferably 20-30°C.

[0023] Preferably, after the reaction is completed and cooled, the reaction product is washed with a solvent, excess sulfur impurities are removed by vacuum filtration, and then dried. The drying temperature is preferably 60-80°C. The drying time is preferably 2-4 hours. The solvent used in the washing process can be CCl4 or CS2.

[0024] Based on the same inventive concept, the present invention also provides an application of a layered polysulfide positive electrode material in a battery or a capacitor, preferably in a lithium-sulfur battery or a sodium-sulfur battery.

[0025] Further preferably, the energy density of the solid-state battery made of the positive electrode made of the layered polysulfide positive electrode material is 500-1000Wh kg -1 , power density is 2000-4000Wkg -1 .

[0026] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0027] The layered polysulfide positive electrode material Nb3TiP2S provided by the present invention 18 Se3 is obtained by the matrix material Nb4P2S 21 Ti and Se co-doping is performed, where Ti occupies the Nb site and Se occupies the S site. As a positive electrode material, Ti doping can stabilize Nb4P2S 21 The electrode material of the present invention has a structure of [PS4] / [PSe4] and [NbS6] / [NbSe6], and Se doping can improve conductivity. The [PS4] / [PSe4] structural unit has a strong PS bond, which can effectively anchor polysulfides, thereby preventing capacity loss caused by polysulfide dissolution. The [NbS6] / [NbS6] structural unit has a stable two-dimensional structure and excellent conductivity, which can effectively buffer the volume expansion caused by the conversion reaction, thereby improving cycle stability and rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Nb3TiP2S prepared in Example 1 of the present invention 18 SEM image of Se3 sample;

[0029] Figure 2 Nb3TiP2S prepared in Example 1 of the present invention 18 Powder XRD pattern of Se3 sample;

[0030] Figure 3 Nb3TiP2S prepared in Example 1 of the present invention 18 Cyclic voltammetry curve of Se3 sample;

[0031] Figure 4 Nb3TiP2S prepared in Example 1 of the present invention 18 Se3 and Nb4P2S 21 The constant current charge-discharge cycle performance of the samples as solid-state battery positive electrodes, of which 4a is at 1C (200mAh g -1 ) is the charge-discharge cycle performance at a constant current density, and 4b is the charge-discharge cycle performance at different current densities;

[0032] Figure 5 Nb3TiP2S prepared in Example 1 of the present invention 18 Comparison of the solid-state battery power density of Se3 cathode and SC composite cathode in the literature;

[0033] Figure 6 Nb3TiP2S prepared in Example 2 of the present invention 18 Powder XRD diffraction pattern of Se3 sample;

[0034] Figure 7 Nb3TiP2S prepared in Example 3 of the present invention 18 Powder XRD diffraction pattern of Se3 sample;

[0035] Figure 8 Nb3TiP2S prepared in Example 4 of the present invention 18 Powder XRD diffraction pattern of Se3 sample;

[0036] Figure 9 The Nb3TiP2S prepared in Example 5 of the present invention 18 Powder XRD diffraction pattern of Se3 sample;

[0037] Figure 10 Nb3TiP2S prepared in Example 6 of the present invention 18 Powder XRD diffraction pattern of Se3 sample;

[0038] Figure 11 Nb3TiP2S prepared in Example 7 of the present invention 18 Powder XRD diffraction pattern of Se3 sample;

[0039] Figure 12 Nb3TiP2S prepared in Example 8 of the present invention 18 Powder XRD diffraction pattern of Se3 sample;

[0040] Figure 13 Nb3TiP2S prepared in Example 9 of the present invention 18 Powder XRD diffraction pattern of Se3 sample;

[0041] Figure 14 Nb3TiP2S prepared in Example 10 of the present invention 18 Powder XRD diffraction pattern of Se3 sample. DETAILED DESCRIPTION

[0042] The present invention aims to solve the problems of poor conductivity, large volume expansion and polysulfide shuttling of the S cathode in current Na-S batteries. By designing a dual-functional structure, the [PS4] / [PSe4] structural unit is combined with layered transition metal sulfides NbS2 / NbSe2 to prepare a new layered polysulfide cathode Nb3TiP2S 18 Se3, which is combined with Nb4P2S 21 Has a similar structure, where Ti occupies the Nb site and Se occupies the S site. As a cathode material, Ti doping can stabilize Nb4P2S 21 The structure of [PS4] / [PSe4] and [NbS6] / [NbSe6] structures are improved by Se doping, and the [PS4] / [PSe4] structural elements have strong PS bonds, which can effectively anchor polysulfides, thereby preventing capacity loss caused by polysulfide dissolution. The [NbS6] / [NbS6] structural elements have a stable two-dimensional structure and excellent conductivity, which can effectively buffer the volume expansion caused by the conversion reaction, improving cycle stability and rate performance. It can be used not only in Na-S batteries, but also in other batteries and capacitors, such as lithium-sulfur batteries, supercapacitors, and ion capacitors.

[0043] The following is a detailed description of a layered polysulfide cathode material, a preparation method, and an application of the present invention, with reference to the accompanying drawings and specific examples. The advantages and features of the present invention will become more apparent from the following description.

[0044] Example 1

[0045] Nb3TiP2S 18Solid phase synthesis of Se3 cathode materials:

[0046] Weigh each element according to the molar ratio of Nb:Ti:P:S:Se of 3:1:2:18:4, control the total mass to 1.074g, grind it thoroughly to mix it evenly, and obtain a mixed powder. The mixed powder is encapsulated in a pre-vacuumed quartz tube (filling ratio is 1 / 6), reacted in a muffle furnace at 600℃ for 12 hours, and then cooled to room temperature at a rate of 5℃ / min to obtain a sample. The sample is taken out, crushed, washed with CS2, and dried to obtain the Nb3TiP2S 18 Se3 positive electrode material. Figure 1 SEM shows that the prepared Nb3TiP2S 18 Se3 has a nanoparticle morphology. Figure 2 The powder XRD pattern shows that the obtained Nb3TiP2S 18 Se 31 The peak shape is completely consistent with the standard peak, and no obvious impurities appear.

[0047] The obtained Nb3TiP2S 18 Se3 sample is made into sodium battery positive electrode: Nb3TiP2S 18 Se3 sample, conductive carbon SP, and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 8:1:1. An appropriate amount of N-methylpyrrolidone (NMP) or deionized water was added and stirred at room temperature for 12 hours to uniformly disperse the active material. The prepared slurry was evenly applied to the current collector using a 200-micron film applicator and dried in a vacuum oven set at 100°C for 8 hours to prepare a sodium positive electrode sheet.

[0048] The button cell uses a Na sheet as the counter electrode and is assembled in an argon atmosphere glove box with a water content of less than 0.5 ppm and an oxygen content of less than 0.5 ppm. After the battery is left to rest for 8 hours, the electrochemical performance test is performed on a blue electric test system with a voltage range of 1-3 V (Vs.Na / Na + ).

[0049] Nb3TiP2S 18 Electrochemical properties of Se3 cathode materials: Figure 3-Figure 4 Nb3TiP2S 18 Se3 cathode material at 0.1mV s -1 The CV curves at a scan rate of 1.95V and the constant current charge-discharge cycle at 1C. There are three pairs of redox peaks in the voltage range of 1-3V, 1.95 / 2.17V corresponding to S 2- / S - The redox reaction of Nb is 1.56 / 1.72V and 1.12 / 1.53V.5+ / Nb 4+ Redox reaction of Nb3TiP2S 18 The Se3 cathode exhibits excellent cycling stability in a PDOL-based solid electrolyte, maintaining 300 mAh g after 150 cycles at 1C. -1 The specific capacity corresponds to 500Wh kg -1 Energy density. 21 After 150 cycles, it can only maintain about 90mAh g -1 At the same time, Nb3TiP2S 18 The solid-state battery with Se3 as the positive electrode can still maintain 129mAh g under 10C conditions. -1 The specific capacity corresponds to 2100Wkg -1 power density.

[0050] See Figure 5 , comparing the power density of this embodiment with the power density of solid-state batteries with positive electrodes made by combining S with other materials, the power density of the positive electrode of this embodiment is much higher than the battery power density of other electrodes. It should be noted that: in order to address the two major challenges currently faced by Na-S batteries, researchers often use S and other materials to make electrodes. The power density of the battery made of the following researchers' positive electrode materials is compared with the power density of this embodiment. Figure 5 ; Figure 5 The numbers #1-#5 in the figure correspond to the materials prepared in references 1-5, respectively.

[0051] Reference 1 - Yuxun Ren et al., “Sodium-Sulfur Batteries Enabled by a Protected Inorganic / Organic Hybrid Solid Electrolyte,” ACS Energy Lett. 2021, 6, 345-353;

[0052] Reference 2 - Tao An et al., “Material and Interfacial Modification toward aStable Room-Temperature Solid-State Na-S Battery,” ACS Appl. mater. Interfaces 2020, 12, 20563-20569;

[0053] Reference 3 - Xiulin Fan et al., “High-Performance All-Solid-State Na-S Batteries Enabled by Casting-Annealing Technology,” ACS Nano 2018, 12, 3360-3368;

[0054] Reference 4 - Xingwen Yu et al., “Sodium-Sulfur Batteries with a Polymer-Coated NASICON-type Sodium-Ion Solid Electrolyte,” Matter 1, 439-451, August 7, 2019;

[0055] Reference 5 - Dong Zhou et al., “A Stable Quasi-Solid-State Sodium–Sulfur Battery,” Angew. Chem. Int. Ed. 2018, 57, 10168–10172.

[0056] Example 2

[0057] Nb3TiP2S 18 Solid phase synthesis of Se3 cathode materials:

[0058] Weigh each element according to the molar ratio of Nb:Ti:P:S:Se=3:1:2:18:4, control the total mass to 1.170g, grind it thoroughly to mix it evenly, and obtain a mixed powder. The mixed powder is encapsulated in a pre-vacuumed quartz tube (filling ratio is 1 / 6), reacted in a muffle furnace at 500℃ for 6 hours, and then cooled to room temperature at a rate of 5K / min to obtain a sample. After the sample is taken out and crushed, it is washed with CCl4 and dried to obtain the Nb4P2S 21 Positive electrode material. Powder XRD pattern (see Figure 6 ) It can be seen that the obtained Nb3TiP2S 18 The peak shape of Se3 is completely consistent with the standard peak, and no obvious impurities appear. 18 The electrochemical performance of Se3 positive electrode material is similar to that of Example 1.

[0059] Example 3

[0060] Nb3TiP2S 18 Solid phase synthesis of Se3 cathode materials:

[0061] Weigh each drug in a molar ratio of NbS2:Ti:P:S:Se=3:1:2:12:4, control the total mass to 1.170g, grind it thoroughly to mix it evenly, and obtain a mixed powder. The mixed powder is encapsulated in a pre-vacuumed quartz tube (filling ratio is 1 / 6), reacted in a muffle furnace at 550℃ for 12 hours, and then cooled to room temperature at a rate of 5K / min to obtain a sample. The sample is taken out, crushed, washed with CS2, and dried to obtain the Nb4P2S 21 Positive electrode material. Powder XRD (see Figure 7 ) comparison shows that Nb3TiP2S 18 The peak shape of Se3 is completely consistent with the standard peak, and no obvious impurities appear. 18 The electrochemical performance of Se3 positive electrode material is similar to that of Example 1.

[0062] Example 4

[0063] Nb3TiP2S 18 Solid phase synthesis of Se3 cathode materials:

[0064] Weigh each drug in a molar ratio of NbS2:Ti:P:S:Se=3:1:2:12:4, control the total mass to 1.074g, grind it thoroughly to mix it evenly, and obtain a mixed powder. The mixed powder is encapsulated in a pre-vacuumed quartz tube (filling ratio is 1 / 6), reacted in a muffle furnace at 500℃ for 6 hours, and then cooled to room temperature at a rate of 10K / min to obtain a sample. The sample is taken out, crushed, washed with CCl4, and dried to obtain the Nb3TiP2S 18 Se3 positive electrode material. Powder XRD spectrum (see Figure 8 ) comparison shows that Nb3TiP2S 18 The peak shape of Se3 is completely consistent with the standard peak, and no obvious impurities appear. 18 The electrochemical performance of Se3 positive electrode material is similar to that of Example 1.

[0065] Example 5

[0066] Nb3TiP2S 18 Solid phase synthesis of Se3 cathode materials:

[0067] The drugs were weighed according to the molar ratio of Nb:Ti:P2S5:S:Se=3:1:1:13:4, and the total mass was controlled to be 1.074g. The mixed powder was fully ground to mix uniformly to obtain a mixed powder. The mixed powder was encapsulated in a pre-vacuumed quartz tube (filling ratio of 1 / 7), reacted in a muffle furnace at 500°C for 12 hours, and then cooled to room temperature at a rate of 5K / min to obtain a sample. The sample was taken out, crushed, washed with CS2, and dried to obtain the Nb3TiP2S 18 Se3 positive electrode material. Powder XRD spectrum (see Figure 9 ) comparison shows that Nb3TiP2S 18 The peak shape of Se3 is completely consistent with the standard peak, and no obvious impurities appear. 18 The electrochemical performance of Se3 positive electrode material is similar to that of Example 1.

[0068] Example 6

[0069] Nb3TiP2S 18 Solid phase synthesis of Se3 cathode materials:

[0070] The drugs were weighed according to the molar ratio of NbS2:Ti:P2S5:S:Se=3:1:1:7:4, and the total mass was controlled to be 1.074g. The mixed powder was fully ground to mix uniformly to obtain a mixed powder. The mixed powder was encapsulated in a pre-vacuumed quartz tube (filling ratio of 1 / 7), reacted in a muffle furnace at 500℃ for 12 hours, and then cooled to room temperature at a rate of 5K / min to obtain a sample. The sample was taken out, crushed, washed with CCl4, and dried to obtain the Nb3TiP2S 18 Se3 positive electrode material. Powder XRD spectrum (see Figure 10 ) comparison shows that Nb3TiP2S 18 The peak shape of Se3 is completely consistent with the standard peak, and no obvious impurities appear. 18 The electrochemical performance of Se3 positive electrode material is similar to that of Example 1.

[0071] Example 7

[0072] Nb3TiP2S 18 Solid phase synthesis of Se3 cathode materials:

[0073] The drugs were weighed according to the molar ratio of NbS2:Ti:P2S5:S:Se=3:1:1:5:4, and the total mass was controlled to be 1.074g. The mixed powder was fully ground to mix uniformly to obtain a mixed powder. The mixed powder was encapsulated in a pre-vacuumed quartz tube (filling ratio of 1 / 7), reacted in a muffle furnace at 600°C for 6 hours, and then cooled to room temperature at a rate of 5K / min to obtain a sample. The sample was taken out, crushed, washed with CS2, and dried to obtain the Nb3TiP2S 18 Se3 positive electrode material. Powder XRD spectrum (see Figure 11 ) comparison shows that Nb3TiP2S 18 The peak shape of Se3 is completely consistent with the standard peak, and no obvious impurities appear. 18 The electrochemical performance of Se3 positive electrode material is similar to that of Example 1.

[0074] Example 8

[0075] Nb3TiP2S 18 Solid phase synthesis of Se3 cathode materials:

[0076] The drugs were weighed according to the molar ratio of Nb:Ti:P2S5:S:Se=3:1:1:13:4, and the total mass was controlled to be 1.074g. The mixed powder was fully ground to mix uniformly to obtain a mixed powder. The mixed powder was encapsulated in a pre-vacuumed quartz tube (filling ratio of 1 / 7), reacted in a muffle furnace at 550°C for 10 hours, and then cooled to room temperature at a rate of 5K / min to obtain a sample. The sample was taken out, crushed, washed with CS2, and dried to obtain the Nb3TiP2S 18 Se3 positive electrode material. Powder XRD spectrum (see Figure 12 ) comparison shows that Nb3TiP2S 18 The peak shape of Se3 is completely consistent with the standard peak, and no obvious impurities appear. 18 The electrochemical performance of Se3 positive electrode material is similar to that of Example 1.

[0077] Example 9

[0078] Nb3TiP2S 18 Solid phase synthesis of Se3 cathode materials:

[0079] The drugs were weighed according to the molar ratio of NbS2:Ti:P:S:Se=3:1:2:11:4, and the total mass was controlled to be 1.074g. The mixed powder was evenly mixed by high-energy ball milling to obtain a mixed powder. The mixed powder was encapsulated in a pre-vacuumed quartz tube (filling ratio of 1 / 6), reacted in a muffle furnace at 580°C for 6 hours, and then cooled to room temperature at a rate of 10K / min to obtain a sample. The sample was taken out, crushed, washed with CS2, and dried to obtain the Nb3TiP2S 18 Se3 positive electrode material. Powder XRD spectrum (see Figure 13 ) comparison shows that Nb3TiP2S 18 The peak shape of Se3 is completely consistent with the standard peak, and no obvious impurities appear. 21 The electrochemical performance of the positive electrode material is similar to that of Example 1.

[0080] Example 10

[0081] Nb3TiP2S 18 Solid phase synthesis of Se3 cathode materials:

[0082] The drugs were weighed according to the molar ratio of NbS2:Ti:P2S5:S:Se=3:1:1:7:4, and the total mass was controlled to be 1.074g. The mixed powder was evenly mixed by high-energy ball milling to obtain a mixed powder. The mixed powder was encapsulated in a pre-vacuumed quartz tube (filling ratio of 1 / 6), reacted in a muffle furnace at 500°C for 4 hours, and then cooled to room temperature at a rate of 5K / min to obtain a sample. The sample was taken out, crushed, washed with CCl4, and dried to obtain the Nb3TiP2S 18 Se3 positive electrode material. Powder XRD spectrum (see Figure 14 ) comparison shows that Nb3TiP2S 18 The peak shape of Se3 is completely consistent with the standard peak, and no obvious impurities appear. 18 The electrochemical performance of the Se3 positive electrode material can be similar to that of Example 1.

[0083] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the scope of protection of the present invention.

Claims

1. A layered polysulfide positive electrode material, characterized in that: The chemical formula of the layered polysulfide is Nb3TiP2S 18 Se3, Nb3TiP2S 18 Se3 is obtained by the matrix material Nb4P2S 21 The cathode material is obtained by co-doping Ti and Se, wherein Ti occupies the Nb position and Se occupies the S position. The cathode material has [PS4] / [PSe4] structural elements and [NbS6] / [NbSe6] structural elements. The [PS4] / [PSe4] structural elements have strong PS / P-Se bonds and can anchor polysulfides.

2. A method for preparing a layered polysulfide positive electrode material according to claim 1, characterized in that: Nb or NbS2, Ti, P or P2S5, S and Se are selected as raw materials, mixed, and reacted at 450-650° C. in a vacuum to obtain the layered polysulfide positive electrode material; wherein the molar ratio of Nb, Ti, P, S, and Se is 3:1:2:16-18:3-5; or The molar ratio of NbS2, Ti, P, S and Se is 3:1:2:10-12:3-5; or The molar ratio of Nb, Ti, P2S5, S and Se is 3:1:1:11-13:3-5; or The molar ratio of NbS2, Ti, P2S5, S and Se is 3:1:1:5-7:3-5.

3. The method for preparing a layered polysulfide positive electrode material according to claim 2, wherein: The molar ratio of Nb, Ti, P, S and Se is 3:1:2:18:4; or The molar ratio of NbS2, Ti, P, S and Se is 3:1:2:12:4; or The molar ratio of NbS2, Ti, P, S and Se is 3:1:2:11:4; or The molar ratio of Nb, Ti, P2S5, S and Se is 3:1:1:13:4; or The molar ratio of NbS2, Ti, P2S5, S and Se is 3:1:1:7:4; or The molar ratio of NbS2, Ti, P2S5, S and Se is 3:1:1:5:

4.

4. The method for preparing a layered polysulfide positive electrode material according to claim 2, wherein: Before the reaction, the raw materials are packaged in a pre-vacuumed quartz tube, and the filling ratio of the raw materials in the quartz tube is 1 / 7-1 / 6.

5. The method for preparing a layered polysulfide positive electrode material according to claim 2, wherein: The vacuum pressure is less than 10 mPa; And / or, the reaction time is 4-24 hours.

6. The method for preparing a layered polysulfide positive electrode material according to claim 2, wherein: After the reaction was completed, the temperature was lowered to room temperature at a rate of 5-10°C / min.

7. The method for preparing a layered polysulfide positive electrode material according to claim 2, wherein: After the reaction is completed and cooled, the reaction product is washed with a solvent, excess S impurities are removed by vacuum filtration, and then dried; Wherein, the drying temperature is 60-80° C.; and the drying time is 2-4 hours.

8. Use of the layered polysulfide positive electrode material according to claim 1 in a battery or a capacitor.

9. Use of the layered polysulfide cathode material according to claim 8 in a battery or capacitor, characterized in that: The energy density of the solid-state battery made of the positive electrode made of the layered polysulfide positive electrode material is 500-1000 Wh kg -1 , power density is 2000~4000 Wkg -1 .

10. Use of the layered polysulfide positive electrode material according to claim 8 in a battery or a capacitor, characterized in that: The battery is a lithium-sulfur battery or a sodium-sulfur battery.

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