Flexible self-supported lithium-sulfur battery positive electrode material containing boron-vanadium-tungsten compound and preparation method of flexible self-supported lithium-sulfur battery positive electrode material

Abstract

The invention discloses a flexible self-supported lithium-sulfur battery positive electrode material containing a boron-containing vanadium-tungsten compound and a preparation method of the flexible self-supported lithium-sulfur battery positive electrode material. Flexible carbon cloth (CC) is used as a substrate, and the B-V-WS2 composite material with double doping of negative and positive ions of boron (B) and vanadium (V) is designed. Wherein the three-dimensional sheet structure of the 1T-phase WS2 exposes abundant active sites, so that the conversion efficiency of the polysulfide is further improved; the electronic structure and the catalytic activity of the WS2 are remarkably regulated and controlled by the double-doping advantage of B and V. The co-doping of B and V not only enhances the adsorption capacity of WS2 to polysulfide, but also accelerates the sulfur redox reaction kinetics, thereby effectively inhibiting the shuttle effect and improving the sulfur utilization rate. In addition, B and V doping stabilizes the 1T phase structure and inhibits the 1T phase structure from being converted into a 2H phase with thermodynamic stability in the cycle process, so that the stability of the battery in the cycle process is remarkably improved. By virtue of the advantages, excellent cycling stability and rate capability are realized after the material is applied to the lithium-sulfur battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-sulfur batteries, and particularly relates to a flexible self-supporting lithium-sulfur battery cathode material containing a boron-vanadium-tungsten composite and a preparation method thereof. Background Art

[0002] Electrochemical energy storage devices, especially those with high energy density, are becoming the focus of technology and the market. Among them, lithium-sulfur batteries based on lithium anodes and sulfur cathodes can provide high energy density. Although lithium-sulfur batteries are regarded as excellent alternatives to lithium-ion batteries due to their high theoretical capacity and high energy density, the energy density and cycle stability of actual lithium-sulfur batteries are usually restricted by many factors. Among them, slow sulfur redox kinetics and the shuttle effect of polysulfides are the main obstacles to the development of lithium-sulfur batteries, and these factors will inevitably lead to a decrease in sulfur utilization and cycle stability. To alleviate the above problems, a series of modification strategies can be adopted to explore how to accelerate sulfur redox kinetics, thereby optimizing the electrochemical performance of lithium-sulfur batteries.

[0003] Currently, layered transition metal chalcogenides (such as WS 2 ) as typical two-dimensional (2D) nanomaterials, with their high specific surface area and layered structure conducive to ion transport, can improve the performance of lithium-sulfur batteries to a certain extent. However, WS 2 still has some disadvantages in practical applications: slow sulfur redox kinetics, serious polysulfide shuttle effect, poor cycle stability, and fast capacity decay, etc., which limit its further application in lithium-sulfur batteries (Advanced Engineering Materials 2023, 25(20): 2300542; Advanced Functional Materials 2024, 34(3): 2309437). Therefore, effective modification means are needed to optimize its performance.

[0004] Limitations of existing modification methods: (1) Heterostructure construction: Although heterojunctions can improve electron transport and catalytic activity, their preparation process is complex, and their adsorption and conversion effects on polysulfides are limited, making it difficult to completely solve the shuttle effect problem; (2) Crystal phase regulation: By controlling the crystal phase of WS 2 (such as 1T phase and 2H phase), the conductivity and catalytic activity can be improved, but the effect of single crystal phase regulation is limited. Especially during long-term cycling, the 1T phase is prone to transform into the 2H phase, resulting in performance degradation; (3) Single-element doping: Single-element doping (such as B or V doping) can partially improve WS 2Its electronic structure and catalytic performance, but its scope of action is limited, the ability to adsorb and convert polysulfides is not significantly improved, and the shuttle effect problem remains prominent, as shown in (Small 2023, 19(11): 2206926; Materials Today Chemistry 2024, 42: 102351; Applied Surface Science 2022, 599 154022). Summary of the Invention

[0005] Aiming at the serious shuttle effect of polysulfides and the slow conversion rate of polysulfides during the reaction process of existing lithium-sulfur batteries, which lead to poor cycle stability and fast capacity decay, the purpose of the present invention is to provide a flexible self-supporting lithium-sulfur battery cathode material containing a boron-vanadium-tungsten composite and its preparation method, which can effectively adsorb polysulfides and promote the conversion of polysulfides, and has excellent cycle stability and rate performance.

[0006] A flexible self-supporting lithium-sulfur battery cathode material containing a boron-vanadium-tungsten composite, and the preparation materials of the lithium-sulfur battery cathode material include B-V-WS 2 @CC, elemental sulfur, and the B-V-WS 2 @CC is the composite material after the reaction, and the composite material includes a conductive carbon material substrate carbon cloth and B and V-WS 2 materials grown on the surface of the conductive carbon material substrate.

[0007] Further, the content of elemental sulfur in the B-V-WS 2 @CC / S composite is 10 wt% to 50 wt%.

[0008] Further, the B content in the B-V-WS2@CC composite accounts for 0% to 10% of WS2.

[0009] Further, the V content in the B-V-WS 2 @CC composite accounts for 0% to 10% of WS 2 .

[0010] The present invention also provides a preparation method for the above battery cathode material, which is applied to the above flexible self-supporting lithium-sulfur battery cathode material containing a boron-vanadium-tungsten composite, and includes the following steps: (1) Clean the carbon cloth, acidify the carbon cloth to obtain the final required carbon cloth; (2) Add a tungsten source, a sulfur source, a boron source, and a vanadium source to a solvent and stir vigorously to obtain a mixed solution; (3) Pour the treated carbon cloth obliquely into the mixed solution, and after the reaction, treat it to obtain an intermediate, denoted as B / V-WS 2 @CC; (4) Cut the intermediate and soak it in a solution of sulfur powder dissolved in CS 2 and treat it. Under a protective atmosphere, heat the material for temperature percolation to obtain the cathode material B-V-WS 2 @CC / S of the lithium-sulfur battery.

[0011] Furthermore, in step (1), the size of the carbon cloth is 2 × 4~5 cm 2 , the acid used for acidification treatment is concentrated nitric acid with a concentration of 12 mol L -1 , and the dosage is 40~48 ml; the post-acidification treatment is heating at 90~100 °C for 6~8 h, then continuously performing ultrasonic cleaning three times with deionized water and 99% alcohol, and vacuum drying for 12~15 h.

[0012] Furthermore, in step (2), the tungsten source is sodium tungstate; the sulfur source is thioacetamide; the boron source is boric acid; the vanadium source is ammonium metavanadate, and the molar ratio of the tungsten source, sulfur source, boron source, and vanadium source is 90:518:0.9~9:0.9~9; the solvent is N,N-dimethylformamide (DMF).

[0013] Furthermore, in step (3), the reaction temperature is 200 °C and the reaction time is 20 h; after the reaction, take out the carbon cloth with the grown material, and the treatment operation is to rinse the carbon cloth with deionized water and 99% alcohol, and vacuum dry for 12~15 h to prepare the intermediate B-V-WS 2 @CC composite material.

[0014] Furthermore, in step (4), the protective atmosphere is one of nitrogen, helium, and argon, the heating rate is 2~4 °C / min, and it is maintained at a temperature of 155~180 °C for 11~14 h to obtain B-V-WS 2 @CC / S composite material.

[0015] The present invention also provides a lithium-sulfur battery, and the positive electrode of the lithium-sulfur battery is made of the above-mentioned lithium-sulfur battery positive electrode material.

[0016] The beneficial effects of the present invention are as follows: The present invention proposes a synergistic modification strategy of co-doping B and V combined with 1T-phase WS 2 . By hydrothermal method, 1T-phase WS with a three-dimensional flaky structure is grown on a flexible carbon cloth 2 , and the dual doping of B and V cations and anions is introduced, significantly improving the cycling performance of WS 2 in the lithium-sulfur battery. The specific advantages are: (1) The co-doping of B and V cations and anions not only synergistically enhances WS 2Its conductivity and catalytic activity also inhibit the transformation to the thermodynamically stable 2H phase during cycling by stabilizing the 1T phase structure, thus significantly improving the cycling stability and capacity retention rate; (2) As the core preparation process, the hydrothermal method can efficiently synthesize three-dimensional flaky 1T-phase WS 2 under mild conditions. Its process is simple and easy to scale up. Meanwhile, by precisely regulating the morphology and crystal phase, more active sites of WS 2 are exposed to improve the catalytic performance; (3) This method combines a flexible carbon cloth substrate, which not only provides excellent conductivity and mechanical support but also sufficient space for high sulfur loading, effectively preventing the damage of the electrode sheet. Through the synergistic effect of B and V co-doping and 1T-phase WS 2 , this material exhibits high sulfur utilization rate, significantly inhibited shuttle effect, and excellent cycling stability in lithium-sulfur batteries, providing an innovative solution to solve the bottleneck problems of traditional lithium-sulfur batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 X-ray diffraction patterns of 1.5%-B-V-WS 2 @CC prepared in Example 1 and V-WS 2 @CC prepared in Comparative Example 2, B-WS 2 @CC prepared in Comparative Example 3, and WS 2 @CC prepared in Comparative Example 1, and the X-ray diffraction standard card of 2H-WS 2 .

[0018] Figure 2 Relaxation, folding, twisting, and rolling test diagrams of 1.5%-B-V-WS 2 @CC / S in Example 1.

[0019] Figure 3 Rate performance diagrams of 1.5%-B-V-WS 2 @CC / S prepared in Example 1, WS 2 @CC / S prepared in Comparative Example 1, V-WS 2 @CC / S prepared in Comparative Example 2, and B-WS 2 @CC / S prepared in Comparative Example 3.

[0020] Figure 4 Cycling performance diagram of 1.5%-B-V-WS 2 @CC / S with high sulfur loading prepared in Example 1.

[0021] Figure 5 Cycling performance diagrams of 1.5%-B-V-WS 2 @CC / S prepared in Example 1 and 3%-B-V-WS 2@CC / S, 5%-B-V-WS prepared in Example 3 2 Cycling performance graph of @CC / S at a current density of 1C.

[0022] Figure 6 1.5%-B-V-WS prepared in Example 1 2 @CC / S and WS prepared in Comparative Example 1 2 Raman graph of @CC.

[0023] Figure 7 1.5%-B-V-WS prepared in Example 1 2 , WS prepared in Comparative Example 1 2 , V-WS prepared in Comparative Example 2 2 , B-WS prepared in Comparative Example 3 2 CV curve graph of the symmetric battery. Detailed implementation method

[0024] The present invention will be further described in detail below through examples, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following examples.

[0025] Example 1 (1) Clean the carbon cloth (CC). First, cut a piece with a size of 2 × 4~5 cm 2 , and the acid used for acidification treatment is 12 mol / L -1 concentrated nitric acid, and the dosage is 40~48 ml; the post-acidification treatment is heating at 90~100 °C for 6~8 h, then continuously performing ultrasonic cleaning three times with deionized water and 99% alcohol, and vacuum drying for 12~15 h.

[0026] (2) Dissolve 0.48 g of sodium tungstate (Na 2 WO 4 ·2H 2 O), 0.0015 g of boric acid (H 3 BO 3 ), 0.003 g of ammonium metavanadate (NH 4 VO 3 ) and 0.63 g of thioacetamide (TAA) in 36 ml of N,N-dimethylformamide (DMF) solution, stir strongly for 1 h and then pour it into a 60 ml polytetrafluoroethylene inner liner. Incline the carbon cloth and place it in the above mixed solution, and heat at 200 °C for 20 h. After the reaction, take out the carbon cloth with the material grown on it, rinse the carbon cloth with deionized water and 99% alcohol, and vacuum dry for 12 h to prepare 1.5%-B-V-WS 2 @CC composite material.

[0027] (3) Dissolve 0.2 g of sulfur powder in 5 ml of CS 2 solution. Cut the carbon cloth (2 × 4~5 cm 2 ) treated in step (2) into circular electrodes with a diameter of 10 mm. Then immerse the electrodes in the sulfur-containing CS 2 solution for 10 minutes and dry at 45 °C for 12 hours. Heat the electrodes in vacuum at 155 °C for 12 hours to obtain a 1.5%-B-V-WS -2 @CC / S cathode material with a sulfur loading of about 2 mg cm 2 .

[0028] Example 2 (1) Clean the carbon cloth (CC). First, cut it into a size of 2 × 4~5 cm 2 . The acid used for acidification treatment is concentrated nitric acid with a concentration of 12 mol L -1 , and the dosage is 40~48 ml. The post-acidification treatment is to heat at 90~100 °C for 6~8 h, then perform ultrasonic cleaning three times successively with deionized water and 99% alcohol, and vacuum dry for 12~15 h.

[0029] (2) Dissolve 0.48 g of sodium tungstate (Na 2 WO 4 ·2H 2 O), 0.003 g of boric acid (H 3 BO 3 ), 0.006 g of ammonium metavanadate (NH 4 VO 3 ) and 0.63 g of thioacetamide (TAA) in 36 ml of N,N-dimethylformamide (DMF) solution. After strong stirring for 1 h, pour it into a 60 ml polytetrafluoroethylene inner liner. Place the carbon cloth obliquely into the above mixed solution and heat at 200 °C for 20 h. After the reaction, take out the carbon cloth with the material grown on it, rinse the carbon cloth with deionized water and 99% alcohol, and vacuum dry for 12 h to prepare a 3%-B / V-WS 2 @CC composite material.

[0030] (3) Dissolve 0.2 g of sulfur powder in 5 ml of CS 2 solution. Cut the carbon cloth (2 × 4~5 cm 2 ) treated in step (2) into circular electrodes with a diameter of 10 mm. Then immerse the electrodes in the sulfur-containing CS 2 solution for 10 minutes and dry at 45 °C for 12 hours. Heat the electrodes in vacuum at 155 °C for 12 hours to obtain a 3%-B-V-WS with a sulfur loading of about 2 mg cm -2 @CC2 @CC / S positive electrode material.

[0031] Example 3 (1) Clean the carbon cloth (CC). First, cut a piece with a size of 2 × 4 - 5 cm 2 , and the acid used for acidification treatment is concentrated nitric acid with a concentration of 12 mol / L -1 , and the dosage is 40 - 48 ml; the post-acidification treatment is to heat at 90 - 100 °C for 6 - 8 h, then perform ultrasonic cleaning three times continuously with deionized water and 99% alcohol, and vacuum dry for 12 - 15 h.

[0032] (2) Dissolve 0.48 g of sodium tungstate (Na 2 WO 4 ·2H 2 O), 0.005 g of boric acid (H 3 BO 3 ), 0.01 g of ammonium metavanadate (NH 4 VO 3 ) and 0.63 g of thioacetamide (TAA) in 36 ml of N,N-dimethylformamide (DMF) solution, stir strongly for 1 h and then pour it into a 60 ml polytetrafluoroethylene inner liner. Place the carbon cloth obliquely into the above mixed solution and heat at 200 °C for 20 h. After the reaction, take out the carbon cloth with the grown material, rinse the carbon cloth with deionized water and 99% alcohol, and vacuum dry for 12 h to prepare a 5%-B / V-WS 2 @CC composite material.

[0033] (3) Dissolve 0.2 g of sulfur powder in 5 ml of CS 2 solution. Cut the 2 × 4 - 5 cm 2 carbon cloth treated in step (2) into circular pole pieces with a diameter of 10 mm. Then immerse the pole pieces in the CS 2 solution containing sulfur for 10 minutes and dry at 45 °C for 12 hours. Heat the pole pieces in vacuum at 155 °C for 12 hours to obtain a 5%-B-V-WS -2 @CC / S positive electrode material with a sulfur loading of about 2 mg / cm 2 .

[0034] Comparative Example 1 (1) Clean the carbon cloth (CC). First, cut a piece with a size of 2 × 4 - 5 cm 2 , and the acid used for acidification treatment is concentrated nitric acid with a concentration of 12 mol / L -1 , and the dosage is 40 - 48 ml; the post-acidification treatment is to heat at 90 - 100 °C for 6 - 8 h, then perform ultrasonic cleaning three times continuously with deionized water and 99% alcohol, and vacuum dry for 12 - 15 h.

[0035] (2) Dissolve 0.495 g of sodium tungstate (Na 2 WO 4 ·2H 2 O) and 0.63 g of thioacetamide (TAA) in 36 ml of N,N-dimethylformamide (DMF) solution. After vigorously stirring for 1 h, pour it into a 60 ml polytetrafluoroethylene liner. Incline the treated CC and place it into the above mixed solution, and heat at 200 °C for 20 h. After the reaction, take out the carbon cloth with the material grown on it, rinse the carbon cloth with deionized water and 99% alcohol, and dry it in vacuum for 12 h to prepare the WS 2 @CC composite material.

[0036] (3) Dissolve 0.2 g of sulfur powder in 5 ml of CS 2 solution. Cut the carbon cloth of 2 × 4~5 cm 2 treated in step (2) into circular electrodes with a diameter of 10 mm. Then immerse the electrodes in the CS 2 solution containing sulfur for 10 minutes, and dry at 45 °C for 12 hours. Heat the electrodes in vacuum at 155 °C for 12 hours to obtain the WS -2 @CC / S cathode material with a sulfur loading of about 2 mg cm 2 .

[0037] Comparative Example 2 (1) Clean the carbon cloth (CC). First, cut it into a size of 2 × 4~5 cm 2 . The acid used for acidification treatment is 12 mol L -1 concentrated nitric acid, and the dosage is 40~48 ml; the post-acidification treatment is heating at 90~100 °C for 6~8 h, then perform ultrasonic cleaning three times continuously with deionized water and 99% alcohol, and dry in vacuum for 12~15 h.

[0038] (2) Dissolve 0.48 g of sodium tungstate (Na 2 WO 4 ·2H 2 O), 0.63 g of thioacetamide (TAA) and 0.003 g of ammonium metavanadate (NH 4 VO 3 ) in 36 ml of N,N-dimethylformamide (DMF) solution. After vigorously stirring for 1 h, pour it into a 60 ml polytetrafluoroethylene liner. Incline the treated CC and place it into the above mixed solution, and heat at 200 °C for 20 h. After the reaction, take out the carbon cloth with the material grown on it, rinse the carbon cloth with deionized water and 99% alcohol, and dry it in vacuum for 12 h to prepare the V-WS 2 @CC composite material.

[0039] (3) Dissolve 0.2 g of sulfur powder in 5 ml of CS 2 solution. Cut the carbon cloth (2 × 4 - 5 cm) processed in step (2) into circular electrodes with a diameter of 10 mm. Then immerse the electrodes in the sulfur-containing CS 2 solution for 10 minutes and dry at 45 °C for 12 hours. Heat the electrodes in vacuum at 155 °C for 12 hours to obtain a V-WS 2 @CC / S cathode material with a sulfur loading of about 2 mg cm -2 2

[0040] Comparative Example 3 (1) Clean the carbon cloth (CC). First, cut a piece with dimensions of 2 × 4 - 5 cm 2 , and the acid used for acidification treatment is 12 mol / L -1 concentrated nitric acid, with a dosage of 40 - 48 ml; the post-acidification treatment is heating at 90 - 100 °C for 6 - 8 h, then performing ultrasonic cleaning three times successively with deionized water and 99% alcohol, and vacuum drying for 12 - 15 h.

[0041] (2) Dissolve 0.48 g of sodium tungstate (Na 2 WO 4 ·2H 2 O), 0.63 g of thioacetamide (TAA), and 0.0015 g of boric acid (H 3 BO 3 ) in 36 ml of N,N-dimethylformamide (DMF) solution. After strong stirring for 1 h, pour it into a 60 ml polytetrafluoroethylene liner. Incline the treated CC and place it into the above mixed solution, and heat at 200 °C for 20 h. After the reaction, take out the carbon cloth with the material grown on it, rinse the carbon cloth with deionized water and 99% alcohol, and vacuum dry for 12 h to prepare a B-WS 2 @CC composite material.

[0042] (3) Dissolve 0.2 g of sulfur powder in 5 ml of CS 2 solution. Cut the carbon cloth (2 × 4 - 5 cm) processed in step (2) into circular electrodes with a diameter of 10 mm. Then immerse the electrodes in the sulfur-containing CS 2 solution for 10 minutes and dry at 45 °C for 12 hours. Heat the electrodes in vacuum at 155 °C for 12 hours to obtain a B-WS 2 @CC / S cathode material with a sulfur loading of about 2 mg cm -2 2 ​​​​

[0043] The cathode materials prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, 3 were made into cathode electrode sheets, and then lithium sheets were used as the anode to assemble a lithium-sulfur battery.

[0044] The cathode materials prepared in Example 1 and Comparative Examples 1, 2, 3 were made into electrode sheets, and then the carbon cloth electrode sheet without sulfur infiltration was placed in an oven and dried at 50 °C for 12 h. The carbon cloth electrode sheet was directly used as the working electrode and the counter electrode to assemble a symmetric battery.

[0045] Figure 1 It shows that the shift of the (002) characteristic peak clearly indicates the formation of the 1T phase. On the matrix of WS 2 , the XRD peaks shifted slightly and no other impurity peaks appeared, proving the successful incorporation of B and V.

[0046] Figure 2 It shows that when the material is relaxed again, it still maintains good integrity and no deformation occurs, indicating that the material grown on the carbon cloth has good mechanical stability.

[0047] Figure 3 It shows that the battery of 1.5%-B-V-WS 2 @CC / S still has the highest discharge capacity (1081.62 mAh g -1 ) after 100 cycles, and the electrochemical cycling performance of this material is excellent.

[0048] Figure 4 It shows that for 1.5%-B-V-WS 2 @CC / S with a sulfur loading of 5.0 mg cm -2 , when the current density is 0.1 C, its initial areal capacity is as high as 6.01 mAh cm -2 , and the areal capacity is still 4.64 mAh cm -2 after 100 cycles, indicating that 1.5%-B-V-WS 2 @CC is a good high-sulfur-loading cathode material for lithium-sulfur batteries.

[0049] Figure 5 It shows that 1.5%-B-V-WS 2 @CC / S has more excellent cycling performance among the materials prepared with different doping ratios.

[0050] Figure 6 Raman spectroscopy tests show that at 353 and 418 cm -1 , due to the in-plane E 1 2g and A 1 g vibration modes of WS 2 characteristic peaks, indicating the 2H phase WS2 Formation. After the co-doping of B and V, the Raman active modes located in the low-frequency region J 1 (131 cm -1 ) and J 2 (188 cm -1 ) can be observed, indicating the stable formation of the 1T phase WS 2 . By comparing the Raman spectra before and after doping, it can be observed that the peaks of J 1 and J 2 symbolizing the 1T phase are significantly enhanced, proving that the doping of B and V is beneficial to promoting the stable formation of more 1T-WS 2 .

[0051] Figure 7 shows that the reduction peak corresponds to the conversion of S 8 to LiPSs, and then further reduction to Li 2 S / Li 2 S 2 , while the oxidation peak represents the decomposition of Li 2 S into soluble LiPSs. The smaller spacing between the oxidation and reduction peaks of the symmetric cell indicates the rapid and reversible conversion of LiPSs. It can be seen that compared with Comparative Examples 1, 2, and 3, the 1.5%-B-V-WS 2 prepared in Example 1 has a higher peak current and a smaller oxidation-reduction peak potential, indicating its strong catalytic ability for the conversion of polysulfides.

[0052] The above is only the preferred specific embodiment of the present invention and is not used to limit the protection scope of the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are all included in the protection scope of the present invention.

Claims

1. A flexible self-supporting lithium-sulfur battery positive electrode material containing a boron-vanadium-tungsten composite, characterized in that: The preparation materials of the lithium-sulfur battery positive electrode material include BV-WS2@CC and elemental sulfur. The BV-WS2@CC is a composite material after the reaction. The composite material includes a conductive carbon material base carbon cloth and a BV-WS2 material grown on the surface of the conductive carbon material base.

2. The flexible self-supporting lithium-sulfur battery positive electrode material containing boron, vanadium and tungsten composite according to claim 1, characterized in that: In the BV-WS2@CC complex, B accounts for 1%~10% of WS2.

3. The flexible self-supporting lithium-sulfur battery positive electrode material containing boron, vanadium and tungsten composite according to claim 1, characterized in that: In the BV-WS2@CC complex, V accounts for 1%~10% of WS2.

4. The flexible self-supporting lithium-sulfur battery positive electrode material containing boron, vanadium and tungsten according to claim 1, characterized in that: The content of elemental sulfur is 10wt% to 50wt%.

5. A method for preparing a positive electrode material for a battery, applied to the flexible self-supporting positive electrode material for a lithium-sulfur battery containing a boron-vanadium-tungsten composite as claimed in claim 1, characterized in that: The following steps are involved: (1) cleaning the carbon cloth and acidifying the carbon cloth to obtain the final desired carbon cloth; (2) adding a tungsten source, a sulfur source, a boron source, and a vanadium source into a solvent and vigorously stirring to obtain a mixed solution; (3) pouring the treated carbon cloth into the mixed solution at an angle, and performing post-reaction treatment to obtain B and V co-doped tungsten disulfide loaded on the carbon cloth (BV-WS2@CC); (4) The intermediate is cut, immersed in a solution of sulfur powder dissolved in CS2 and treated to obtain an initial electrode sheet. Under a protective atmosphere, the electrode sheet is heated and sulfurized to obtain a lithium-sulfur battery positive electrode material BV-WS2@CC / S.

6. The method for preparing a flexible self-supporting lithium-sulfur battery positive electrode material containing a boron-vanadium-tungsten composite according to claim 5, characterized in that: In step (1), the size of the carbon cloth is 2 × 4~5 cm 2 The acid used for the acidification treatment was 12 mol L -1 The amount of concentrated nitric acid used is 40-48 ml; the post-acidification treatment is heating at 90-100°C for 6-8 h, then ultrasonic cleaning is performed three times in succession with deionized water and 99% alcohol, and vacuum drying is performed for 12-15 h.

7. The method for preparing a flexible self-supporting lithium-sulfur battery positive electrode material containing a boron-vanadium-tungsten composite according to claim 5, characterized in that: In step (2), the tungsten source is sodium tungstate; the sulfur source is thioacetamide; the boron source is boric acid; the vanadium source is ammonium metavanadate, and the molar ratio of the tungsten source, the sulfur source, the boron source, and the vanadium source is 90:518:0.9~9:0.9~9; and the solvent is N,N-dimethylformamide (DMF).

8. The method for preparing a flexible self-supporting lithium-sulfur battery positive electrode material containing a boron-vanadium-tungsten composite according to claim 5, characterized in that: In step (3), the reaction temperature is 200° C. and the reaction time is 20 h. After the reaction, the carbon cloth with the material is taken out, and the treatment operation is to rinse the carbon cloth with deionized water and 99% alcohol, and vacuum dry it for 12 to 15 h to prepare the intermediate BV-WS2@CC composite material.

9. The method for preparing a flexible self-supporting lithium-sulfur battery positive electrode material containing a boron-vanadium-tungsten composite according to claim 5, characterized in that: In step (4), the protective atmosphere is one of nitrogen, helium, and argon, the heating rate is 2 to 4°C / min, and the temperature is maintained at 155 to 180°C for 11 to 14 h to obtain a BV-WS2@CC / S composite material.

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