A method for preparing a WO3 / NWSPC / CNT composite material
By preparing WO3/NWSPC/CNT composite materials, the problems of conductivity and structural stability of lithium-ion battery anode materials were solved, achieving high specific capacity and good cycle performance, making it suitable for lithium-ion battery anode materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUIYANG (GUIZHOU) NEW ENERGY MATERIALS CO LTD
- Filing Date
- 2024-03-11
- Publication Date
- 2026-07-31
AI Technical Summary
The specific capacity of graphite, an existing lithium-ion battery anode material, is limited and cannot meet the requirements of next-generation electronic devices. Transition metal oxides such as WO3 have problems with poor conductivity and structural instability, which leads to deterioration in cycle capacity and rate performance.
A WO3/NWSPC/CNT composite material was prepared by solvothermal method using carbon nanotubes and water-soluble bitumen combined with WO3. This method provides more active sites and improves conductivity, thereby enhancing the material's cycle stability and electrochemical performance.
The specific capacity and cycle stability of the material were improved, and the electrochemical performance was significantly enhanced. The capacity of pure WO3 increased from 342 mAh/g to 915 mAh/g, and the rate performance was also significantly improved.
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Figure CN118084062B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery manufacturing, and particularly relates to a method for preparing a WO3 / NWSPC / CNT composite material for lithium-ion battery anodes. Background Technology
[0002] With the escalating environmental pollution crisis and the looming depletion of fossil fuels, the development of renewable energy and sustainable energy storage technologies has attracted global attention. In particular, lithium-ion batteries (LIBs), due to their high energy density and coulombic efficiency, low self-discharge characteristics, and ultra-long lifespan, have brought about revolutionary changes and are widely used in hybrid vehicles and various portable devices. Graphite is the most popular anode material in commercial lithium-ion batteries, but its specific capacity is limited (372 mAh g / g). -1 The current technology cannot meet the requirements of next-generation electronic devices. Therefore, it is imperative to develop alternative energy storage materials with larger reversible capacity and higher power density.
[0003] Due to the high theoretical specific capacity of transition metal oxides (500-1000 mAh g⁻¹), -1 Transition metal oxides (TMOs) have been extensively studied as stable and low-cost anode materials for lithium-ion batteries. Among them, tungsten trioxide (WO3) stands out due to its abundant Earth resources, environmental friendliness, diverse crystal phases, and high theoretical capacity (693 mAh g⁻¹). -1 TMOs have become potential candidate materials. However, poor conductivity and structural instability are inherent defects of TMOs, and the insulation and volume changes of pristine WO3 during charge and discharge processes lead to deterioration of cycle capacity and rate performance.
[0004] To address the aforementioned drawbacks, innovative TMOs / carbon composites are currently considered a viable strategy. By combining TMOs with various carbon-based materials (including carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon cloth (CC), graphene, and their derivatives), numerous TMO-based hybrids are prepared. These carbon-based composites improve the conductivity and distribution of nanomaterials, thereby significantly enhancing electrochemical performance. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing a WO3 / NWSPC / CNT composite material, which uses carbon nanotubes, water-soluble asphalt, and WO3 to provide more active sites and defects for lithium-ion storage, effectively improving the specific capacity and cycle stability of the material.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A method for preparing a WO3 / NWSPC / CNT composite material includes the following steps:
[0008] 1) Mix 0.5–2 g of sodium tungstate with 20–50 mL of N-methylpyrrolidone and stir for 20–50 min;
[0009] 2) Add 20-60 mL of concentrated hydrochloric acid with a mass concentration of 30%-38% to the mixed solution in step 1), and continue stirring for 20-50 min; add 0.2-1 g of carbon nanotubes, and then stir for 20-50 min; then add 0.05-0.2 g of urea and 0.3-0.7 g of water-soluble coal tar pitch, and then stir for 0.5-2 h;
[0010] 3) Transfer the mixture obtained in step 2) to a reaction vessel, place the reaction vessel in a forced-air drying oven, and solvothermal react at 150-200℃ for 10-16 hours;
[0011] 4) Remove the mixture from the reactor, wash it with water 3-5 times, acid wash it 3-5 times, and then dry it in a drying oven at 80-100℃ for 10-14 hours;
[0012] 5) Carbonize the dried powder in a tube furnace at 500-800℃ for 2-5 hours under nitrogen atmosphere;
[0013] 6) Collect the carbonized finished product.
[0014] The method for preparing water-soluble coal tar pitch includes the following steps:
[0015] 1) Use medium-temperature coal tar pitch powder with a particle size of less than 0.3 mm as raw material for later use;
[0016] 2) Prepare a mixed acid solution by taking 50-80 mL of H2SO4 and 20-50 mL of HNO3. Add 5-10 g of medium-temperature coal tar pitch powder to the mixed acid solution in small amounts several times. React at a constant temperature of 40-50℃ for 5-7 hours.
[0017] 3) After the reaction is complete, pour the solution into 500-800 mL of deionized water to terminate the reaction;
[0018] 4) Heat filter or centrifuge the filter cake until it is neutral, then mix the filter cake with 400-800 ml of NaOH solution until the pH is above 11, stir at 80-100℃ for 1-2 hours to fully dissolve it, filter and collect the filtrate;
[0019] Adjust the pH to below 3 with HCl until a precipitate forms. Centrifuge again and wash with deionized water until no Cl is visible. - exist;
[0020] 5) Finally, dry at a constant temperature of 80-100℃ for 12-14 hours to obtain water-soluble asphalt.
[0021] The volume ratio of H2SO4 to HNO3 in the mixed acid solution is 7:3.
[0022] The concentration of NaOH mentioned in step 4) is 1-2 mol / L.
[0023] The concentration of HCl mentioned in step 4) is 1 mol / L.
[0024] Compared with the prior art, the beneficial effects of the present invention are:
[0025] This invention utilizes sodium tungstate as the tungsten precursor and successfully prepares a WO3 / NWSPC / CNT composite material by combining carbon nanotubes, water-soluble coal tar pitch, and WO3 through a one-step solvothermal process. The synergistic effect of these three components improves the material's conductivity and structural stability, thereby enhancing its electrochemical performance. The material was applied to lithium-ion anode materials, and its electrochemical performance was evaluated. Electrochemical data showed that WO3 alone had a capacity of only 342 mAh / g at a current density of 0.1 A / g, while after being combined with the two carbon nanotubes, the capacity increased to 915 mAh / g after 100 cycles. This demonstrates that introducing two carbon nanotubes to combine with WO3 significantly improves its electrochemical performance. Attached Figure Description
[0026] Figure 1 This is a flowchart of the preparation process of WO3 / NWSPC / CNT composite material.
[0027] Figure 2 This is the XRD pattern of the WO3 / NWSPC / CNT composite material.
[0028] Figure 3 This is a SEM image of the WO3 / NWSPC / CNT composite material.
[0029] Figure 4 This is a nitrogen adsorption-desorption curve of the WO3 / NWSPC / CNT composite material.
[0030] Figure 5 This is a pore size distribution diagram of the WO3 / NWSPC / CNT composite material.
[0031] Figure 6 This is a graph showing the cycling performance of the WO3 / NWSPC / CNT composite material at a current density of 100 mA / g.
[0032] Figure 7 The middle section shows the rate performance of the WO3 / NWSPC / CNT composite material at current densities ranging from 100 mA / g to 5000 mA / g. Detailed Implementation
[0033] The present invention will now be described in detail with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.
[0034] See Figure 1 A method for preparing a WO3 / NWSPC / CNT composite material includes the following steps:
[0035] 1) Mix 0.5–2 g of sodium tungstate with 20–50 mL of N-methylpyrrolidone and stir for 20–50 min;
[0036] 2) Add 20-60 mL of concentrated hydrochloric acid with a mass concentration of 30%-38% to the mixed solution in step 1), and continue stirring for 20-50 min; add 0.2-1 g of carbon nanotubes, and then stir for 20-50 min; then add 0.05-0.2 g of urea and 0.3-0.7 g of water-soluble coal tar pitch, and then stir for 0.5-2 h;
[0037] 3) Transfer the mixture obtained in step 2) to a reaction vessel, place the reaction vessel in a forced-air drying oven, and perform a solvothermal reaction (water or ethylene glycol) at 150-200℃ for 10-16 hours;
[0038] 4) Remove the mixture from the reactor, wash it with water 3-5 times, acid wash it 3-5 times, and then dry it in a drying oven at 80-100℃ for 10-14 hours;
[0039] 5) Carbonize the dried powder in a tube furnace at 500-800℃ for 2-5 hours under nitrogen atmosphere;
[0040] 6) Collect the carbonized finished product.
[0041] A method for preparing water-soluble asphalt includes the following steps:
[0042] 1) The medium-temperature coal tar pitch is crushed and sieved (particle size 0.2-0.3 mm) and used as raw material for later use.
[0043] 2) Prepare a mixed acid solution (volume ratio 7:3) by mixing 50-80 mL of H2SO4 and 20-50 mL of HNO3 in a three-necked flask. Then, add 5-10 g of sieved coal tar pitch to the mixed acid solution in small amounts several times. Set the water bath temperature (oxidation temperature) to 40-50℃ and react at this temperature for 5-7 hours.
[0044] 3) After the reaction is complete, pour the solution into 500-800 mL of deionized water to terminate the reaction.
[0045] 4) Heat filter or centrifuge to separate the filter cake until neutral. Then mix the filter cake with 1-2 mol / L NaOH solution (400-800 ml) until the pH is greater than 11. Stir at 80-100℃ for 1-2 hours until fully dissolved. After centrifugation, filter and collect the filtrate. Then use 1 mol / L... -1 Adjust the pH to less than 3 with HCl until a precipitate forms. Centrifuge again and wash with deionized water until no Cl is visible. - exist.
[0046] 5) Finally, dry at a constant temperature of 80-100℃ for 12-14 hours to obtain water-soluble asphalt.
[0047] Example 1:
[0048] See Figure 1 The preparation of the composite material WO3 / NWSPC / CNT-0.3 includes the following steps:
[0049] 1) Add 0.5-1g of sodium tungstate to a beaker containing 40-50mL of N-methylpyrrolidone and stir for 20-50min.
[0050] 2) Add 20-30 mL of 30%-38% concentrated hydrochloric acid to the beaker and continue stirring for 20-50 minutes.
[0051] 3) Continue to add 0.3g of carbon nanotubes (CNTs), and then stir for 20-50 minutes.
[0052] 4) Continue to add 0.05-0.1g of urea and 0.5-0.7g of water-soluble coal tar pitch (WSP), and then stir for 0.5-2 hours.
[0053] 5) Transfer the mixture in the beaker to the reaction vessel, place the reaction vessel in a forced-air drying oven, and solvothermal react at 150-200℃ for 10-16 hours.
[0054] 6) Remove the mixture from the reactor, wash it with water 3 to 5 times, acid wash it 3 to 5 times, and then dry it in a drying oven at 80 to 100°C for 10 to 14 hours.
[0055] 7) Carbonize the dried powder in a tube furnace at 500-800℃ for 2-5 hours under nitrogen conditions.
[0056] 8) Collect the carbonized sample and name it WO3 / NWSPC / CNT-0.3.
[0057] Example 2
[0058] The preparation of the composite material WO3 / NWSPC / CNT-0.5 includes the following steps, see [link to details]. Figure 1 :
[0059] 1) Add 1-2g of sodium tungstate to a beaker containing 40-50mL of N-methylpyrrolidone and stir for 20-50min.
[0060] 2) Add 20-30 mL of 30-38% concentrated hydrochloric acid to the beaker and continue stirring for 20-50 minutes.
[0061] 3) Continue to add 0.5g of carbon nanotubes (CNTs), and then stir for 20-50 minutes.
[0062] 4) Continue to add 0.05-0.1g of urea and 0.5-0.7g of water-soluble coal tar pitch (WSP), and then stir for 0.5-2 hours.
[0063] 5) Transfer the mixture in the beaker to the reaction vessel, place the reaction vessel in a forced-air drying oven, and solvothermal react at 150-200℃ for 10-16 hours.
[0064] 6) Remove the mixture from the reactor, wash it with water 3 to 5 times, acid wash it 3 to 5 times, and then dry it in a drying oven at 80 to 100°C for 10 to 14 hours.
[0065] 7) Carbonize the dried powder in a tube furnace at 500-800℃ for 2-5 hours under nitrogen conditions.
[0066] 8) Collect the carbonized sample and name it WO3 / NWSPC / CNT-0.5.
[0067] Example 3
[0068] The preparation of the composite material WO3 / NWSPC / CNT-0.7 includes the following steps, see [link to details]. Figure 1 :
[0069] 1) Add 0.5-1g of sodium tungstate to a beaker containing 40-50mL of N-methylpyrrolidone and stir for 20-50min.
[0070] 2) Add 20-40 mL of 30-38% concentrated hydrochloric acid to the beaker and continue stirring for 20-50 minutes.
[0071] 3) Continue to add 0.7g of carbon nanotubes (CNTs), and then stir for 20-50 minutes.
[0072] 4) Continue to add 0.05-0.1g of urea and 0.5-0.7g of water-soluble coal tar pitch (WSP), and then stir for 0.5-2 hours.
[0073] 5) Transfer the mixture in the beaker to the reaction vessel, place the reaction vessel in a forced-air drying oven, and solvothermal react at 150-200℃ for 10-16 hours.
[0074] 6) Remove the mixture from the reactor, wash it with water 3 to 5 times, acid wash it 3 to 5 times, and then dry it in a drying oven at 80 to 100°C for 10 to 14 hours.
[0075] 7) Carbonize the dried powder in a tube furnace at 500-800℃ for 2-5 hours under nitrogen conditions.
[0076] 8) Collect the carbonized sample and name it WO3 / NWSPC / CNT-0.7.
[0077] Depend on Figure 2 It is known that the XRD pattern of pure WO3 samples shows prominent sharp peaks, indicating that the synthesized material sample has good crystallinity. All diffraction peaks in the XRD pattern of the WO3 sample match well with the monoclinic phase (JCPDS: 98-000-6556), proving that the prepared pure WO3 has a monoclinic crystal structure. However, while keeping other experimental parameters constant, the diffraction peaks of WO3 in the WO3 / NWSPC / CNT composite material are completely different from the monoclinic structure as the carbon nanotube content increases. These diffraction peaks conform to the typical hexagonal structure of WO3 (JCPDS: 98-001-3851). Here, the carbon nanotube content plays an important role in adjusting the crystal phase. When the carbon nanotube content is zero or low, the prepared WO3 has a monoclinic phase structure; when the carbon nanotube content increases to an appropriate level, the prepared WO3 exhibits a hexagonal phase crystal structure.
[0078] Depend on Figure 3 As can be seen, the pure WO3 sample exhibits a layered, flower-like structure composed of nanosheets. High-magnification SEM images show that these nanosheets each have sharp edges. This morphological feature corresponds to a monoclinic phase structure. Furthermore, the WO3 sample in the WO3 / NWSPC / CNT composite material displays a nanorod-like morphology. This morphology conforms to a hexagonal structure. The SEM analysis results are consistent with the XRD results. Notably, the morphological transformation from nanosheets to nanorods is attributed to the amount of carbon nanotubes. Therefore, we observe that the carbon nanotube content not only controls the crystalline phase but also modulates the morphology.
[0079] Depend on Figure 4It can be seen that the three-dimensional porous structure inherited from the dual-carbon structure was evaluated by analyzing the N2 adsorption / desorption isotherms of the WO3 / NWSPC / CNT composite material. According to the IUPAC definition, both the dual-carbon and WO3 / NWSPC / CNT composite materials exhibit Type IV isotherm characteristics, indicating the presence of a mesoporous structure. Within the relative pressure range of 0.2–1.0, the WO3 / NWSPC / CNT composite material exhibits a more pronounced Type H3 hysteresis loop, indicating the presence of a porous structure in the dual-carbon structure. The specific surface areas of WO3, NWSPC / CNT, WO3 / NWSPC / CNT-0.3, WO3 / NWSPC / CNT-0.5, and WO3 / NWSPC / CNT-0.7 are 5.302 m². 2 / g, 110.107m 2 / g, 149.537m 2 / g, 156.262m 2 / g, 176.139m 2 / g. The increase in the specific surface area of the composite material comes from two factors: the high specific surface area of the two-carbon phase and the fact that the specific surface area of the hexagonal WO3 nanorods is larger than that of the monoclinic phase WO3. This can be explained by the one-dimensional morphology.
[0080] The pore sizes of each sample measured by the DFT method are as follows: Figure 5 As shown, the total pore volumes of WO3, NWSPC / CNT, WO3 / NWSPC / CNT-0.3, WO3 / NWSPC / CNT-0.5, and WO3 / NWSPC / CNT-0.7 are 0.0221 cm³. 3 / g, 0.2667cm 3 / g, 0.3259cm 3 / g, 0.4702cm 3 / g and 0.4633cm 3 / g. The composite material WO3 / NWSPC / CNT has a larger specific surface area than the pure monoclinic phase WO3, which can provide more electrochemical reaction sites for the effective transport of electrolyte ions, indicating that its reactivity can be improved.
[0081] Electrochemical tests were performed on the CR2032 coin cell material, see [link to relevant documentation]. Figure 6 The cycling performance graph of the WO3 / NWSPC / CNT composite material shows that the reversible capacity of WO3 after 100 cycles is 342 mAh / g, indicating that the WO3 precursor does not exhibit excellent electrochemical performance when used as a lithium-ion battery anode material. After dual-carbon composite formation, the capacity of WO3 / NWSPC / CNT-0.5 after 100 cycles increases to 915 mAh / g. This demonstrates that introducing dual carbons to composite WO3 significantly improves its electrochemical performance.
[0082] from Figure 7 As can be seen, the capacity of WO3 is almost zero under high current density, indicating that the rate performance of this sample is poor. This may be because WO3 has undergone a relatively serious volume expansion phenomenon, which not only prolongs the diffusion path of lithium ions, but also hinders the wetting of the electrolyte, thus limiting the material's capacity. The WO3 / NWSPC / CNT-0.5 sample exhibited lithium storage capacities of 661.4 mAh / g, 563.7 mAh / g, 427.9 mAh / g, 326.8 mAh / g, 245.9 mAh / g, and 109.0 mAh / g after 10 cycles at current densities of 100 mA / g, 200 mA / g, 500 mA / g, 1000 mA / g, 2000 mA / g, and 5000 mA / g, respectively. Even when the current density was returned to 100 mA / g, it still retained a lithium storage capacity of 697.0 mAh / g. Furthermore, at the same current density, the capacity of WO3 / NWSPC / CNT-0.5 was significantly higher than that of other samples, indicating that WO3 / NWSPC / CNT-0.5 possesses the optimal lithium storage performance.
Claims
1. A method for preparing a WO3 / NWSPC / CNT composite material, characterized in that, Includes the following steps: 1) Mix 0.5–2 g of sodium tungstate with 20–50 mL of N-methylpyrrolidone and stir for 20–50 min; 2) Add 20-60 mL of concentrated hydrochloric acid with a mass concentration of 30%-38% to the mixed solution in step 1), and continue stirring for 20-50 min; add 0.2-1 g of carbon nanotubes, and then stir for 20-50 min; then add 0.05-0.2 g of urea and 0.3-0.7 g of water-soluble coal tar pitch, and then stir for 0.5-2 h; 3) Transfer the mixture obtained in step 2) to a reaction vessel, place the reaction vessel in a forced-air drying oven, and solvothermal react at 150-200℃ for 10-16 hours; 4) Remove the mixture from the reactor, wash it with water 3-5 times, acid wash it 3-5 times, and then dry it in a drying oven at 80-100℃ for 10-14 hours; 5) Carbonize the dried powder in a tube furnace at 500-800℃ for 2-5 hours under nitrogen atmosphere; 6) Collect the carbonized finished product.
2. The method for preparing a WO3 / NWSPC / CNT composite material according to claim 1, characterized in that, The method for preparing water-soluble coal tar pitch includes the following steps: 1) Use medium-temperature coal tar pitch powder with a particle size of less than 0.3 mm as raw material for later use; 2) Prepare a mixed acid solution by taking 50-80 mL of H2SO4 and 20-50 mL of HNO3. Add 5-10 g of medium-temperature coal tar pitch powder to the mixed acid solution in small amounts several times. React at a constant temperature of 40-50℃ for 5-7 hours. 3) After the reaction is complete, pour the solution into 500-800 mL of deionized water to terminate the reaction; 4) Heat filter or centrifuge the filter cake until it is neutral, then mix the filter cake with 400-800 ml of NaOH solution until the pH is above 11, stir at 80-100℃ for 1-2 hours to fully dissolve it, filter and collect the filtrate; Again use HCl to adjust PH to 3 or below, at this time there is precipitate, centrifugal separation again, use deionized water to wash until no Cl - there is; 5) Finally, dry at a constant temperature of 80-100℃ for 12-14 hours to obtain water-soluble asphalt.
3. The method for preparing a WO3 / NWSPC / CNT composite material according to claim 2, characterized in that, The volume ratio of H2SO4 to HNO3 in the mixed acid solution is 7:
3.
4. The method for preparing a WO3 / NWSPC / CNT composite material according to claim 2, characterized in that, The concentration of NaOH mentioned in step 4) is 1-2 mol / L.
5. The method for preparing a WO3 / NWSPC / CNT composite material according to claim 2, characterized in that, The concentration of HCl mentioned in step 4) is 1 mol / L.