Method for synthesizing niobium-tungsten oxide heterojunction material through two-time solvothermal method and application of niobium-tungsten oxide heterojunction material in lithium ion battery
Synthesis of niobium tungsten oxide heterojunction material through two solvent thermal methods has solved the problems of poor conductivity and poor cycle stability of traditional graphite negative electrode materials, achieved high conductivity and good cycle stability of the material, and is suitable for high-power lithium-ion batteries.
Patent Information
- Application Number
- CN202411831058.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-12
- Publication Date
- 2025-03-18
AI Technical Summary
Traditional graphite negative electrode materials are prone to form lithium dendrites during rapid charging and discharging, resulting in irreversible loss of lithium and battery safety problems. They are poor in conductivity and poor cycle stability.
Two-solubilized niobium tungsten oxide heterojunction material was synthesized by two-solubilization method. By adjusting the interphase potential of the material, the energy level barrier is reduced, the Li+ embedding and disengagement rate is improved, and the conductivity and cyclic stability of the material are improved.
It significantly improves the conductivity and rate performance of niobium tungsten oxide materials, can withstand a greater real current density, promotes the rapid deintercalation of lithium ions, and improves the cycling stability and high power performance of lithium ion batteries.
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Figure CN119637939A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of secondary lithium ion batteries, and specifically relates to a method for synthesizing niobium tungsten oxide heterojunction materials by a double solvothermal method and an application thereof in lithium ion batteries. Background Art
[0002] As an important component of new energy storage devices, lithium-ion batteries have been widely used in military and civilian energy storage appliances due to their advantages such as high energy density, high battery voltage, wide operating temperature range, and long storage life. Traditional graphite negative electrode materials cannot get rid of the dilemma of slow kinetics under high power. At the same time, their lithium insertion potential is low (0.2V), and lithium dendrites are easily formed during rapid charging and discharging, causing irreversible loss of lithium and causing battery safety issues. Therefore, it is urgent to develop a Li-ion battery that can perform rapid charging and discharging. + A new type of negative electrode material with high intercalation and deintercalation properties, low temperature resistance, high energy density and long cycle life.
[0003] Niobium tungsten oxide negative electrode material has a high theoretical capacity and good rate performance, and has ideal electrochemical properties. It is a wide temperature range, high safety lithium-ion battery negative electrode material. It has received widespread attention in recent years and is suitable for a variety of special application scenarios. However, its low electrical conductivity leads to poor conductivity, and its cycle stability is poor in a small current charge and discharge environment. The construction of heterojunction structure has always been considered one of the most effective strategies to improve the kinetic performance of lithium-ion battery negative electrodes. The construction of heterojunction structure can effectively reduce the interphase potential between electrodes, improve the conductivity of the negative electrode of lithium-ion batteries, and thus improve the electrochemical performance of the negative electrode. Summary of the invention
[0004] The purpose of the present invention is to effectively regulate the interphase potential to reduce the energy level barrier, so as to accelerate the ion and electron transmission rate and improve the discharge capacity. A method for synthesizing niobium tungsten oxide heterojunction material by two solvothermal methods and its application in lithium ion batteries are provided. The synthesized niobium tungsten oxide heterojunction material can be used as a negative electrode material for lithium ion batteries. By regulating the interphase potential of the material, the energy level barrier is reduced, and the Li + The embedding and extraction rates in the crystal structure show electrochemical properties such as high capacity and high stability. In addition, the niobium tungsten oxide precursor and heterojunction are synthesized by two solvothermal methods respectively. Different precursors can be regulated in the process, and then a variety of different heterojunction structures can be synthesized for complex scenarios.
[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:
[0006] A method for synthesizing niobium tungsten oxide heterojunction materials by a two-step solvothermal method, the method comprising:
[0007] Step 1: uniformly mix the niobium source and the tungsten source, and disperse and dissolve them in anhydrous ethanol;
[0008] Step 2: transferring the mixed solution in step 1 into a Teflon autoclave, reacting at a certain temperature and time, centrifuging, washing, and drying to obtain a niobium tungsten oxide precursor;
[0009] Step 3, uniformly mixing the niobium tungsten oxide precursor and the transition metal ion compound in an organic solvent to obtain a mixed suspension;
[0010] Step 4: transfer the mixed suspension in step 3 to a Teflon high-pressure reactor, react at a certain temperature and time, centrifuge, wash, and dry to obtain a niobium tungsten oxide heterojunction precursor; then, transfer to a tubular furnace for calcination to obtain a niobium tungsten oxide heterojunction.
[0011] Furthermore, in step 1, the niobium source is one of niobium pentachloride, niobium oxalate, niobium powder, and niobium carbide; and the tungsten source is tungsten hexachloride.
[0012] Furthermore, in step 1, the molar ratio of the niobium source to the tungsten source is 9 to 16:3 to 8, preferably, the molar ratio of the niobium source to the tungsten source is 14:3 (Nb 14 W3O 44 )、16:5(Nb 16 W5W 55 )、9:8(Nb 18 W 16 O 93 ).
[0013] Furthermore, in step 1, the niobium source and the tungsten source are dispersed and dissolved in the anhydrous ethanol by magnetic stirring, and the mixing time is 12-15 hours.
[0014] Furthermore, in step 2, the reaction temperature is 180-200° C. and the reaction time is 12-24 hours.
[0015] Furthermore, in step 3, the transition metal ion compound includes NbCl5, C 15 H 21 One of O6V, MoCl5, tin chloride, stannous chloride, ferric chloride or ferrous chloride;
[0016] Furthermore, in step three, the molar ratio of the niobium tungsten oxide precursor to the transition metal ion compound is 0.5-1:1-2; and the organic solvent includes anhydrous ethanol, ethylene glycol or isopropanol.
[0017] Furthermore, in step 4, the reaction temperature is 180-200° C. and the reaction time is 12-24 hours.
[0018] Furthermore, in step 4, the calcination temperature is 800° C., the holding time is 8 hours, and the heating rate is 5° C. / min.
[0019] The niobium tungsten oxide heterojunction material synthesized by the above method is used as a negative electrode material in a lithium ion battery. The niobium tungsten oxide heterojunction is used as a negative electrode material and is dispersed in a solvent according to a certain mass ratio with a conductive agent and a binder to obtain a negative electrode slurry. The slurry is coated on a negative electrode current collector, dried, rolled, and punched to obtain a negative electrode sheet, and then a button battery is assembled; the binder is polyvinylidene fluoride (PVDF), the conductive agent is acetylene black, and the solvent is N-methylpyrrolidone (NMP). The mass ratio of negative electrode active material: conductive agent: binder is 80%:10%:10%.
[0020] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, the heterojunction of niobium tungsten oxide is prepared by the secondary solvothermal method, and the heterostructure reduces the interphase potential of niobium tungsten oxide, improves the conductivity of the material, and greatly improves the rate performance. The complex heterostructure can withstand a larger real current density and is conducive to the rapid deintercalation of lithium ions. The preparation method is conducive to the high-power niobium tungsten oxide negative electrode in the field of lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 Schematic diagram of XRD of the prepared niobium tungsten oxide heterojunction.
[0022] Figure 2 Schematic diagram of the microstructure of the prepared niobium tungsten oxide heterojunction.
[0023] Figure 3 This is the discharge curve of the prepared niobium tungsten oxide heterojunction at 0.2C.
[0024] Figure 4 This is the rate performance diagram of the prepared niobium tungsten oxide heterojunction.
[0025] Figure 5 This is the discharge curve of the prepared niobium tungsten oxide heterojunction at 10C.
[0026] Figure 6 The cyclic performance diagram of the prepared niobium tungsten oxide heterojunction at 0.5C in different embodiments. DETAILED DESCRIPTION
[0027] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention that does not depart from the concept and scope of the technical solution of the present invention should be included in the protection scope of the present invention.
[0028] The preparation method of the present invention prepares a niobium tungsten oxide heterostructure negative electrode by a secondary solvothermal method. The heterostructure is prepared by the secondary solvothermal method, and a variety of different types of heterojunctions can be constructed, which is conducive to adapting to applications in different environments. The constructed heterostructure reduces the energy level barrier of niobium tungsten oxide and improves the electronic conductivity of the material, greatly improving the rate performance. The preparation method can be used in the field of high-power niobium tungsten oxide-based lithium-ion batteries.
[0029] Example 1
[0030] A two-step solvothermal method for synthesizing niobium-tungsten-based heterojunction electrodes for lithium-ion batteries comprises the following methods:
[0031] First heat of dissolution: 16 mmol of niobium pentachloride and 5 mmol of tungsten hexachloride in a molar ratio are uniformly dissolved in 50 mL of anhydrous ethanol, and magnetic stirring is performed for 12 hours to fully mix the mixture. The solution is then transferred to a Teflon autoclave, and reacted for 12 hours at a temperature of 180°C to generate a niobium tungsten oxide precursor, which is then centrifuged, washed, and dried to obtain a niobium tungsten oxide precursor.
[0032] Second solvent thermal: 8 mmol of niobium pentachloride and the obtained precursor were uniformly mixed and dissolved in 50 mL of anhydrous ethanol, and magnetically stirred for 12 hours to fully mix them. The solution was then transferred to a Teflon autoclave and reacted at 180°C for 12 hours to generate a niobium tungsten oxide heterojunction precursor, which was then transferred to a tubular furnace and calcined at 800°C for 8 hours in an air atmosphere at a heating rate of 5°C / min to obtain a niobium tungsten oxide heterojunction material, which was used in lithium-ion batteries to promote the insertion and extraction of lithium ions during the charge and discharge process and improve the cycle stability of lithium-ion batteries. The XRD and SEM images of the material are shown in the figure below. Figure 1 and Figure 2 As shown, obvious characteristic peaks of the two substances can be seen, proving the synthesis of the material, and the main morphology is a rod-like structure with good crystallinity.
[0033] The niobium tungsten oxide heterojunction material prepared above was used to assemble a lithium ion half-cell and test the electrochemical performance. The charge and discharge curves at 0.2C are shown in Figure 2. Figure 3 As shown in Figure 2, the heterostructured niobium tungsten oxide has a significantly higher discharge capacity. Figure 4 As shown, at 100C ultra-high rate niobium tungsten oxide heterojunction still has 86mAhg -1 The discharge capacity is much higher than that of niobium tungsten oxide (31 mAhg -1 ). Long cycle at 10C Figure 5 As shown, the capacity retention rate of the niobium tungsten oxide heterojunction after 250 cycles at a high rate of 10C is 96.6%, which is better than that of niobium tungsten oxide.
[0034] Example 2
[0035] The difference between this embodiment and embodiment 1 is that the molar ratio of the niobium source to the tungsten source in the first solvent thermal treatment is 14:3.
[0036] Example 3
[0037] The difference between this embodiment and embodiment 1 is that the molar ratio of the niobium source to the tungsten source in the first solvent thermal treatment is 9:8.
[0038] Example 4
[0039] The difference between this embodiment and embodiment 1 is that in the second solvent thermal treatment, a corresponding proportion of C 15 H 21 O6V replaces niobium pentachloride.
[0040] Example 5
[0041] The difference between this embodiment and embodiment 1 is that in the second solvothermal treatment, niobium pentachloride is replaced by MoCl5 in a corresponding proportion.
[0042] Example 6
[0043] The difference between this embodiment and embodiment 1 is that in the second solvent thermal treatment, niobium pentachloride is replaced by tin chloride in a corresponding proportion.
[0044] The niobium tungsten oxide material prepared above was used to assemble a lithium ion half-cell and test the electrochemical performance. The discharge cycle diagram at 0.5C is shown in the figure below. Figure 6 The above six embodiments all show high discharge specific capacity and good cycle stability, that is, the capacity retention rate after 200 cycles is above 90%, proving that the niobium tungsten oxide heterojunction has good cycle stability.
Claims
1. A method for synthesizing niobium tungsten oxide heterojunction materials by a double solvothermal method, characterized in that: The method is: Step 1: uniformly mix the niobium source and the tungsten source, and disperse and dissolve them in anhydrous ethanol; Step 2: transferring the mixed solution in step 1 into a Teflon autoclave, reacting at a certain temperature and time, centrifuging, washing, and drying to obtain a niobium tungsten oxide precursor; Step 3, uniformly mixing the niobium tungsten oxide precursor and the transition metal ion compound in an organic solvent to obtain a mixed suspension; Step 4: transfer the mixed suspension in step 3 to a Teflon high-pressure reactor, react at a certain temperature and time, centrifuge, wash, and dry to obtain a niobium tungsten oxide heterojunction precursor; then, transfer to a tubular furnace for calcination to obtain a niobium tungsten oxide heterojunction.
2. The method for synthesizing niobium tungsten oxide heterojunction materials by a double solvothermal method according to claim 1, characterized in that: In step 1, the niobium source is one of niobium pentachloride, niobium oxalate, niobium powder and niobium carbide; and the tungsten source is tungsten hexachloride.
3. The method for synthesizing niobium tungsten oxide heterostructure materials by a double solvothermal method according to claim 1, characterized in that: In step 1, the molar ratio of the niobium source to the tungsten source is 9-16:3-8.
4. The method for synthesizing niobium tungsten oxide heterojunction materials by a double solvothermal method according to claim 1, characterized in that: In step 1, the niobium source and the tungsten source are dispersed and dissolved in anhydrous ethanol by magnetic stirring, and the mixing time is 12-15 hours.
5. The method for synthesizing niobium tungsten oxide heterojunction materials by a double solvothermal method according to claim 1, characterized in that: In step 2, the reaction temperature is 180-200° C. and the reaction time is 12-24 hours.
6. The method for synthesizing niobium tungsten oxide heterojunction materials by a double solvothermal method according to claim 1, characterized in that: In step 3, the transition metal ion compound includes NbCl5, C 15 H 21 One of O6V, MoCl5, tin chloride, stannous chloride, ferric chloride or ferrous chloride.
7. The method for synthesizing niobium tungsten oxide heterojunction materials by a double solvothermal method according to claim 1, characterized in that: In step three, the molar ratio of the niobium tungsten oxide precursor to the transition metal ion compound is 0.5-1:1-2; and the organic solvent includes anhydrous ethanol, ethylene glycol or isopropanol.
8. The method for synthesizing niobium tungsten oxide heterojunction materials by a double solvothermal method according to claim 1, characterized in that: In step 4, the reaction temperature is 180-200° C. and the reaction time is 12-24 hours.
9. The method for synthesizing niobium tungsten oxide heterojunction materials by a double solvothermal method according to claim 1, characterized in that: In step 4, the calcination temperature is 800°C, the holding time is 8 hours, and the heating rate is 5°C / min.
10. Use of the niobium tungsten oxide heterojunction material synthesized by the method according to any one of claims 1 to 9 as a negative electrode material in a lithium ion battery.