WOx-coated WS2 metal-ligand composite material as well as preparation method and application thereof

Abstract

The invention discloses a WOx-WS2 metal-ligand composite material and a preparation method and application thereof, and belongs to the technical field of potassium ion battery motor materials.The preparation method comprises the steps that an ethanol solution of 2-methylimidazole is added into an ethanol solution of a tungsten source, stirring reaction is conducted, solvothermal reaction, washing, vacuum drying and heat treatment are conducted, WOx is obtained, and the WOx-WS2 metal-ligand composite material is obtained. And performing vulcanization reaction on the WOx and a sulfur source in an inert gas environment to obtain the WOx-coated WS2 metal-ligand composite material. The prepared product has a unique metal-ligand structure, can provide more active sites for storage of K < + > in the charge-discharge process, and enhances the storage capacity of K < + >, so that the material can show relatively high capacity. The insertion capability and the storage speed of potassium ions in the electrode material are remarkably improved, so that the electrode material can show excellent rate capability. The synthesis temperature is low, and the synthesis path and reaction conditions are simple; the reaction is easy to control, post-treatment is not needed, and the method is environment-friendly and suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lithium ion battery electrode material preparation, and particularly relates to a WO x WS2 metal-ligand composite material, preparation method and application thereof. BACKGROUND

[0002] With the continuous growth of energy demand, the limitations of lithium ion batteries are increasingly prominent, including safety issues, high production costs, and the scarcity of lithium resources. These defects have prompted researchers to turn their attention to more promising alternative energy storage technologies. Potassium ion batteries have attracted attention due to their similar working principle (typical "rocking chair" mechanism) to lithium ion batteries and the unique advantages of potassium element.

[0003] Potassium not only has similar physical and chemical properties to lithium, but also has abundant reserves in the earth's crust, is widely distributed, has significant advantages such as low cost and high safety, and is therefore considered a strong contender for the next generation of energy storage technology. In the research of potassium ion battery materials, tungsten disulfide (WS2) has become a negative electrode material of great concern due to its unique structural characteristics. WS2 is a layered transition metal sulfide with a crystal structure similar to graphite, but with a larger interlayer spacing and weaker interlayer interaction, which provides favorable conditions for the intercalation / deintercalation of potassium ions. In addition, compared with other transition metal sulfides, WS2 has a smaller volume change during charging and discharging, exhibiting good structural stability. However, WS2 still has some inherent defects in practical application, which have not yet reached the ideal level of electrochemical performance, providing an important direction for subsequent research.

[0004] In view of the existing tungsten disulfide, although it has the advantage of layered structure, its electrochemical performance is low, the potassium ion intercalation / deintercalation kinetics is slow, the structure is unstable during the cycle process due to volume change, the capacity and rate performance need to be improved, and the synthesis often requires high temperature, complex process or harsh conditions, resulting in high cost, high energy consumption, and difficulty in large-scale production. Therefore, it is urgent to conduct modification research to improve the electrochemical performance of WS2 negative electrode, enhance the potassium ion intercalation / deintercalation kinetics, improve the specific capacity and rate performance, and improve the cycle stability, and realize low-temperature, simple, and low-cost large-scale production. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a WO x WS2 metal-ligand composite material, preparation method and application thereof, to solve the technical problem of how to prepare WS2-based negative electrode material with excellent potassium ion storage performance by a low-temperature, simple and controllable synthesis method.

[0006] In order to achieve the above purpose, the present application adopts the following technical solutions: The application discloses a kind of WO x Preparation method of WS2 metal-ligand composite material, comprising: The ethanol solution of 2-methylimidazole is added to the ethanol solution of tungsten source, and after stirring reaction, solvent thermal reaction is carried out, washed, vacuum dried, and after heat treatment, WO x WO x Sulfidation reaction is carried out with sulfur source in inert gas environment to obtain WO x WS2 metal-ligand composite material; the value range of x is 2≤x≤3.

[0007] Preferably, the ethanol solution of 2-methylimidazole is prepared by adding 2.0-3.0 g of 2-methylimidazole to 10-20 mL of ethanol; the tungsten source is tungsten hexachloride, and the ethanol solution of tungsten source is prepared by adding 1.9-2.5 g of tungsten hexachloride to 10-20 mL of ethanol.

[0008] Preferably, the stirring speed of the stirring reaction is 300-500 r / min, and the time is 20-40 min. During the stirring reaction, 1 mL of the ethanol solution of 2-methylimidazole is added to the ethanol solution of tungsten source each time until the addition is completed.

[0009] Preferably, the conditions of the solvent thermal reaction include: reacting at 150-200℃ for 1-3 h.

[0010] Preferably, the conditions of the washing include: washing alternately with deionized water and anhydrous ethanol for 2-5 times.

[0011] Preferably, the conditions of the heat treatment include: heat treatment at 500-800℃ for 1-3 h in an inert gas environment.

[0012] Preferably, the mass ratio of WOx to thioacetamide is (150-300):(500-800).

[0013] Preferably, the conditions of the sulfidation reaction include: mixing WO x The WO

[0014] The application also discloses a kind of WO x Preparation method of WS2 metal-ligand composite material, which is prepared by the above-mentioned preparation method of WS2 metal-ligand composite material. x Preparation method of WS2 metal-ligand composite material, which is prepared by the above-mentioned preparation method of WS2 metal-ligand composite material. xThe WS2 metal-ligand composite material comprises tungsten oxide flower balls, WO2 nanorods grown on the tungsten oxide flower balls, and WS2 covering the surface of the WO2 nanorods; and the WS2 sheet layer spacing is 0.66 nm.

[0015] The application further discloses the WO x The application further discloses a preparation method of the WS2 metal-ligand composite material. x The application further discloses an application of the WS2 metal-ligand composite material in preparation of a lithium ion battery.

[0016] Compared with the prior art, the application has the following beneficial effects: The application discloses a WO x The application discloses a preparation method of the WS2 metal-ligand composite material. x The application discloses a preparation method of the WS2 metal-ligand composite material. x The WS2 metal-ligand composite material has a unique metal-ligand structure, can provide more active sites for storage of K + in the charging and discharging process, enhances the storage capacity of K + , and thus can exhibit higher capacity. x The large interlayer spacing structure of the WS2 composite material can not only store more K + , but also effectively relieve volume changes caused by ion intercalation / deintercalation, reduce pulverization and peeling of the electrode material, and thus improve the cycle stability.

[0017] Further, by accurately controlling the concentration of raw materials, the molar ratio of metal W and ligand 2-methylimidazole can be optimized, precipitation unevenness caused by excessively high concentration or incomplete reaction caused by excessively low concentration can be avoided, and thus the formation of uniform metal-ligand precursors is promoted, the controllable synthesis of the composite material in the subsequent solvothermal reaction is laid a foundation, and the product purity and yield are improved.

[0018] Further, 1 mL of 2-methylimidazole ethanol solution is added to the ethanol solution of the tungsten source each time until the addition is complete, and the reaction rate can be controlled by adding in batches to avoid precipitation aggregation caused by excessive local concentration; the rotation speed of 300-500 r / min ensures sufficient mixing of the solution, and 20-40 min ensures complete reaction, thereby forming uniform precursor particles, providing conditions for uniform growth of the composite material in the subsequent solvothermal reaction, and improving the consistency of the product morphology.

[0019] Further, the reaction temperature and reaction time have a decisive influence on the structure of the product; in the present application, the solvothermal reaction temperature and time must be strictly controlled at 150-200 DEG C for 1-3 h, and excessively high reaction temperature and excessively long reaction time are not conducive to the formation of uniform metal-ligand composite materials, and excessively low reaction temperature and excessively short reaction time are not conducive to the formation of metal-ligand composite materials. Precise control can ensure that the precursor is converted into WO x @WS2 composite material, forming a stable metal-ligand derivative structure, improving the number of potassium ion storage active sites and ion migration rate.

[0020] Further, deionized water and anhydrous ethanol are alternately cleaned 2-5 times. Alternating cleaning can effectively remove residual ions, organic matter and by-products of the reaction, reduce the influence of impurities on the electrochemical performance, improve the purity of the product, and ensure the exposure of the high-activity surface of the composite material, thereby optimizing the potassium ion intercalation / deintercalation efficiency.

[0021] Further, the conditions for heat treatment include: heat treatment at 500-800 DEG C for 1-3 h in an inert gas environment; which can promote the decomposition of the organic ligand in the precursor and the crystallization of WO x . The inert gas prevents tungsten oxide from being excessively oxidized, and high-temperature treatment optimizes the crystal structure of WO x , enhances the structural stability of the material, and provides a suitable substrate for the subsequent sulfuration reaction, thereby improving the cycle stability of the composite material. Under excessively high and low reaction temperature conditions, WO x @WS2 metal-ligand composite material cannot be obtained. Under excessively long and short reaction time conditions, WO x @WS2 metal-ligand composite material cannot be obtained.

[0022] Further, the present application controls the concentration and ratio of the tungsten source and the sulfur source, the reaction temperature, the reaction time, the reaction filling ratio and the drying method, etc. to realize the controllable synthesis of WO x @WS2 metal-ligand composite material, which has high control precision.

[0023] Further, uniform coverage is achieved by gas-phase sulfuration. WO xThe WO2 nanorod is placed in a large porcelain boat, and the sulfur source is placed in a small porcelain boat, so that the diffusion rate of the sulfur vapor can be controlled, and local over-sulfuration or insufficient sulfuration can be avoided; the temperature range of 300-500 DEG C promotes the crystallization of WS2 and prevents the shrinkage of the interlayer spacing; 1-3 hours are guaranteed to ensure sufficient sulfuration but not excessive (to avoid excessive WS2 layers), so that a few-layer, large interlayer spacing WS2 covering structure is finally formed, and the potassium ion diffusion rate and storage capacity are improved.

[0024] The application further discloses the WO x @WS2 metal-ligand composite material prepared by the preparation method. + The 0.66 nm interlayer spacing of the surface WS2 can accommodate more K x , and the few-layer WS2 shortens the ion diffusion path, so that the capacity, rate performance and cycle stability are synergistically improved. The product prepared by the application has uniform chemical composition, high purity and uniform morphology, and can exhibit excellent performance when used as a negative electrode material of a potassium ion battery.

[0025] The application further discloses the WO x @WS2 metal-ligand composite material prepared by the preparation method. x The application further discloses the WO @WS2 metal-ligand composite material in the preparation of a lithium ion battery electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The X-ray diffraction pattern of the WO x @WS2 metal-ligand composite material prepared in Embodiment 1 of the application; Figure 2 The low-magnification scanning electron microscope image of the WO x @WS2 metal-ligand composite material prepared in Embodiment 1 of the application; Figure 3 The high-magnification transmission electron microscope image of the WO x @WS2 metal-ligand composite material prepared in Embodiment 1 of the application; Figure 4 The transmission electron microscope image of the WO x @WS2 metal-ligand composite material prepared in Embodiment 1 of the application; Figure 5 The high-resolution transmission electron microscope image of the WO x @WS2 metal-ligand composite material prepared in Embodiment 1 of the application; DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0028] In the present application, all the embodiments and preferred embodiments mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0029] In the present application, all the technical features and preferred features mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0030] In the present application, the percentage (%) or the part refers to the percentage by weight or the weight part of the composition, if not otherwise specified.

[0031] In the present application, all the components or preferred components mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0032] In the present application, unless otherwise specified, the numerical range "a~b" represents a shorthand notation for any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "6~22" represents that all the real numbers between "6~22" have been listed herein, and "6~22" is only a shorthand notation for these numerical combinations.

[0033] The lower limit and the upper limit of the range disclosed in the present application can be one or more lower limits and one or more upper limits, respectively.

[0034] In the present application, the term "and / or" used herein refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0035] In the present application, unless otherwise specified, each reaction or operation step can be carried out sequentially or according to the sequence. Preferably, the reaction method herein is carried out sequentially.

[0036] Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied in the present application.

[0037] The present application provides a WO x The preparation method of the WS2 metal-ligand composite material comprises the following steps: Step one: 1.9~2.5 g of tungsten hexachloride is added to a beaker containing 10~20 mL of ethanol, and stirred magnetically at room temperature until completely dissolved to obtain solution A; the stirring speed is 300~500 r / min; Step two: 2.0~3.0 g of 2-methylimidazole is added to a beaker containing 10~20 mL of ethanol, and stirred magnetically at room temperature until completely dissolved to obtain solution B; the stirring speed is 300~500 r / min; Step three: solution B is poured into solution A, and 1 mL of solution B is added to solution A each time under continuous magnetic stirring, and the operation is repeated until the addition is completed, and the mixture is stirred until it is fully mixed and uniform, to obtain a precursor solution, and the duration is 20~40 min; Step four: the precursor solution is transferred to a polytetrafluoroethylene liner, and the filling ratio of the polytetrafluoroethylene liner is 55%~65%. After being sealed, it is placed in a homogeneous reactor for solvothermal reaction at 150~200℃ for 1~3 h; Step five: after the solvothermal reaction is completed, the reaction kettle is naturally cooled to room temperature, and then the cooled solvothermal product after reaction is taken out, washed with water and alcohol alternately for 2~5 times, and then the product is collected by filtration or centrifugation, and vacuum dried to obtain a precursor powder; Step six: the precursor powder is placed in a porcelain boat, and the powder is uniformly spread on the porcelain boat, and then placed in a tube furnace for heat treatment in an inert gas environment at 500~800℃ for 1~3 h, and then taken out after cooling in the furnace to obtain WO x material, 2≤x≤3; Step seven: 150~300 mg of the prepared WO x material is uniformly spread in a small porcelain boat, and the porcelain boat is placed in a large porcelain boat containing 500~800 mg of thioacetamide, and then the large porcelain boat is placed in a tube furnace for sulfidation at 300~500℃ in an inert gas environment for 1~3 h. After cooling to room temperature in the furnace, the product in the small porcelain boat is collected to obtain WO x @WS2 composite material; 2≤x≤3; the inert gas is argon.

[0038] The WO x @WS2 metal-ligand composite material has a small number of layers of WS2 with good crystallinity on the surface of the short WO2 nanorod, the interlayer spacing of the surface covered tungsten sulfide is 0.66 nm, which corresponds to the (002) crystal plane of WS2 and the interlayer spacing is slightly expanded, and the main component structure is an unsaturated tungsten oxide flower ball with WO2 nanorods covered with WS2 on the surface, which is derived from the metal-ligand structure.

[0039] The WO x The WS2 metal-ligand composite material is applied in the field of potassium ion batteries, and its unique structural characteristics can make it exhibit excellent electrochemical performance.

[0040] The WO x The WS2 metal-ligand composite material, the preparation method and the application thereof are synthesized by a solvothermal method, using tungsten hexachloride and 2-methylimidazole as raw materials, and then the precursor is calcined and solid-phase sulfidized to obtain WO x The WS2 composite material can exhibit excellent potassium storage performance and has a high reversible capacity when the product is applied in potassium ion storage. x The reaction mechanism of the WS2 composite electrode is mainly dominated by the pseudo-capacitance effect, and the ion migration rate and the conductivity are improved in the reaction process, thereby accelerating the charging and discharging process. In addition, the WS2 layer of the surface layer of the composite material is combined with tungsten oxide with high capacity, the large interlayer spacing and the few-layer structure of WS2 positively promote the storage of potassium ions, and significantly enhance the embedding capacity and storage rate of potassium ions in the electrode material. The WO x The WS2 metal-ligand composite material exhibits excellent electrochemical performance in the application in the field of potassium ion batteries due to its unique structural characteristics.

[0041] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0042] Embodiment 1 The WO x The preparation method of the WS2 metal-ligand composite material comprises the following steps: Step one: 2.3 g of tungsten hexachloride is added to a beaker containing 15 mL of ethanol, and stirred at a speed of 400 r / min until completely dissolved to obtain solution A; Step two: 2.7 g of 2-methylimidazole was added into a beaker containing 15 mL of ethanol, and stirred at a speed of 400 r / min until completely dissolved to obtain solution B; Step three: solution B was poured into solution A, and magnetic stirring was performed to obtain a precursor solution, with a duration of 30 min; Step four: the precursor solution was transferred into a polytetrafluoroethylene liner. After being sealed, the liner was placed into a homogeneous reactor for a solvothermal reaction at 200℃ for 1 h; Step five: after the solvothermal reaction was completed, the reactor was naturally cooled to room temperature, and then the cooled solvothermal product was taken out, washed with water and alcohol for 3 times each, and then the product was collected and vacuum dried to obtain a precursor powder; Step six: the precursor powder was placed into a porcelain boat, and the powder was uniformly spread on the porcelain boat, which was then placed into a tube furnace for heat treatment at 700℃ in an argon environment for 1 h. After the furnace was cooled, the WO x material, 2≤x≤3; Step seven: 200 mg of the prepared WO x material was uniformly spread on a small porcelain boat, and the porcelain boat was placed into a large porcelain boat containing 800 mg of thioacetamide. The large porcelain boat was then placed into a tube furnace for sulfidation at 400℃ in an inert gas environment for 2 h. After the furnace was cooled to room temperature, the product in the small porcelain boat was collected to obtain WO x @WS2 composite material, 2≤x≤3.

[0043] Figure 1 The X-ray diffraction pattern of the WO x @WS2 metal-ligand composite material prepared in Example 1 of the present application; it can be observed from the figure that the diffraction peaks can be well matched with standard cards PDF#68-0134, PDF#42-1260 and PDF#08-0237, indicating that the synthesized product is WO x @WS2 composite material.

[0044] Figure 2 The X-ray diffraction pattern of the WO x @WS2 metal-ligand composite material prepared in Example 1 of the present application; it can be observed from the figure that the diffraction peaks can be well matched with standard cards PDF#68-0134, PDF#42-1260 and PDF#08-0237, indicating that the synthesized product is WO Figure 2 It can be seen from the figure that the obtained product as a whole presents micron flower balls with a diameter of about 2-3 μm.

[0045] Figure 3 The X-ray diffraction pattern of the WO x @WS2 metal-ligand composite material prepared in Example 1 of the present application; it can be observed from the figure that the diffraction peaks can be well matched with standard cards PDF#68-0134, PDF#42-1260 and PDF#08-0237, indicating that the synthesized product is WO Figure 3 It can be seen from the figure that the micron flower balls are composed of curled nanosheets.

[0046] Figure 4WO x @Transmission electron microscopy image of the WS2 metal-ligand composite material prepared in Example 1; from Figure 4 It can be determined from the image that the surface of the shorter WO2 nanorod of the obtained product is covered by a few layers of well-crystallized WS2.

[0047] Figure 5 WO x @High-resolution transmission electron microscopy image of the WS2 metal-ligand composite material prepared in Example 1; from Figure 5 It can be observed from the image that the interplanar spacing of the surface covered tungsten sulfide sheet is 0.66 nm, corresponding to the (002) crystal plane of WS2 and the interplanar spacing is slightly expanded, proving the successful preparation of WO x @WS2 composite material.

[0048] Example 2 A WO x @Method for preparing a WS2 metal-ligand composite material, comprising: Step one: 2.5 g of tungsten hexachloride was added to a beaker containing 20 mL of ethanol, and stirred at a speed of 500 r / min until completely dissolved to obtain solution A; Step two: 3.0 g of 2-methylimidazole was added to a beaker containing 20 mL of ethanol, and stirred at a speed of 500 r / min until completely dissolved to obtain solution B; Step three: solution B was poured into solution A, and magnetic stirring was performed to obtain a precursor solution, with a duration of 40 min; Step four: the precursor solution was transferred to a polytetrafluoroethylene liner. After being sealed, it was placed in a homogeneous reactor for solvothermal reaction, and reacted at 150°C for 3 h; Step five: after the solvothermal reaction was completed, the reaction kettle was naturally cooled to room temperature, and then the cooled solvothermal product after reaction was taken out, washed with water and alcohol alternately for 2 times each, and then the product was collected and vacuum dried to obtain a precursor powder; Step six: the precursor powder was placed in a porcelain boat, and the powder was uniformly spread on the porcelain boat, and then placed in a tube furnace for heat treatment in an argon gas environment at 500°C for 3 h. After cooling in the furnace, the WO x material was obtained, and 2≤x≤3; Step seven: 150 mg of the prepared WO x material was uniformly spread in a small porcelain boat, and the porcelain boat was placed in a large porcelain boat containing 500 mg of thioacetamide, and then the large porcelain boat was placed in a tube furnace for reaction in an inert gas environment at 300°C for 3 h for sulfidation. After cooling to room temperature in the furnace, the product in the small porcelain boat was collected to obtain a WO x @WS2 composite material, and 2≤x≤3.

[0049] Example 3 A WO x A method for preparing a WS2 metal-ligand composite material, comprising: Step one: 1.9 g of tungsten hexachloride was added to a beaker containing 10 mL of ethanol, and stirred at a speed of 300 r / min until completely dissolved to obtain solution A; Step two: 2.0 g of 2-methylimidazole was added to a beaker containing 10 mL of ethanol, and stirred at a speed of 300 r / min until completely dissolved to obtain solution B; Step three: solution B was poured into solution A, and magnetic stirring was performed to obtain a precursor solution, with a duration of 20 min; Step four: the precursor solution was transferred to a polytetrafluoroethylene liner. After being sealed, it was placed in a homogeneous reactor for solvothermal reaction at 160°C for 1.5 h; Step five: after the solvothermal reaction was completed, the reaction kettle was naturally cooled to room temperature, and then the cooled solvothermal product after reaction was taken out, washed with water and alcohol alternately for 4 times, and then the product was collected and vacuum dried to obtain a precursor powder; Step six: the precursor powder was placed in a porcelain boat, and the powder was uniformly spread on the porcelain boat, and then placed in a tube furnace for heat treatment at 600°C in an argon environment for 1.5 h. After cooling in the furnace, the WO2-xS2 was taken out to obtain a WO2-xS2 x material, 2≤x≤3; Step seven: 250 mg of the prepared WO2-xS2 x material was uniformly spread in a small porcelain boat, and the porcelain boat was placed in a large porcelain boat containing 600 mg of thioacetamide. The large porcelain boat was then placed in a tube furnace for reaction at 500°C in an inert gas environment for 1 h for sulfidation. After cooling to room temperature in the furnace, the product in the small porcelain boat was collected to obtain a WO2-xS2 x material, 2≤x≤3.

[0050] Example 4 A WO x A method for preparing a WS2 metal-ligand composite material, comprising: Step one: 2.2 g of tungsten hexachloride was added to a beaker containing 12 mL of ethanol, and stirred at a speed of 350 r / min until completely dissolved to obtain solution A; Step two: 2.6 g of 2-methylimidazole was added to a beaker containing 12 mL of ethanol, and stirred at a speed of 350 r / min until completely dissolved to obtain solution B; Step three: solution B was poured into solution A, and magnetic stirring was performed to obtain a precursor solution, with a duration of 25 min; Step four: transfer the precursor solution into a polytetrafluoroethylene liner. After sealing, put it into a homogeneous reactor for solvothermal reaction, react at 170°C for 2.5 h; Step five: after the solvothermal reaction is completed, the reactor is naturally cooled to room temperature, then the cooled solvothermal product after reaction is taken out, washed with water and alcohol alternately for 5 times, and the product is collected, vacuum dried to obtain a precursor powder; Step six: the precursor powder is placed in a porcelain boat, the powder is evenly spread on the porcelain boat, and then placed in a tube furnace for heat treatment at 800°C in an argon environment for 2.5 h, and then taken out after furnace cooling to obtain WO x material, 2≤x≤3; Step seven: take 300 mg of the prepared WO x material, evenly spread in a small porcelain boat, and place the porcelain boat in a large porcelain boat containing 750 mg of thioacetamide, and then place the large porcelain boat in a tube furnace for reaction at 450°C in an inert gas environment for 2.5 h for sulfuration. After furnace cooling to room temperature, the product in the small porcelain boat is collected to obtain WO x @WS2 composite material, 2≤x≤3.

[0051] Example 5 a WO x @WS2 metal-ligand composite material, comprising: Step one: add 2.4 g of tungsten hexachloride to a beaker containing 18 mL of ethanol, and stir at a speed of 450 r / min until completely dissolved to obtain solution A; Step two: add 2.8 g of 2-methylimidazole to a beaker containing 18 mL of ethanol, and stir at a speed of 450 r / min until completely dissolved to obtain solution B; Step three: pour solution B into solution A and magnetically stir to obtain a precursor solution, for a duration of 35 min; Step four: transfer the precursor solution into a polytetrafluoroethylene liner. After sealing, put it into a homogeneous reactor for solvothermal reaction, react at 180°C for 2 h; Step five: after the solvothermal reaction is completed, the reactor is naturally cooled to room temperature, then the cooled solvothermal product after reaction is taken out, washed with water and alcohol alternately for 3 times, and the product is collected, vacuum dried to obtain a precursor powder; Step six: the precursor powder is placed in a porcelain boat, the powder is evenly spread on the porcelain boat, and then placed in a tube furnace for heat treatment at 650°C in an argon environment for 2 h, and then taken out after furnace cooling to obtain WO x material, 2≤x≤3; Step seven: take 270 mg of the prepared WO xThe material is uniformly spread in a small porcelain boat, the porcelain boat is placed in a large porcelain boat containing 650 mg of thioacetamide, and the large porcelain boat is placed in a tube furnace for reaction under an inert gas environment at 450 DEG C for 2 h for sulfidation. After cooling to room temperature in the furnace, it is taken out, and the product in the small porcelain boat is collected to obtain WO x @WS2 composite material, 2≤x≤3.

[0052] In summary, the present application is a WO x @Preparation method of WS2 metal-ligand composite material, the preparation method is combined by solvothermal method and solid phase sulfidation, using cheap and easily available tungsten hexachloride and thioacetamide as raw materials, and WO x @WS2 composite material, which has the advantages of low synthesis temperature, simple path, no need for large equipment and post-processing, and is suitable for large-scale production; the obtained composite material is composed of tungsten oxide flower balls, WO2 nanorods and surface few-layer WS2 (interlayer spacing 0.66 nm), and its unique structure not only provides more potassium ion storage sites and accelerates ion diffusion through large interlayer spacing and few-layer characteristics, but also improves the cycle stability by relieving volume change, and the metal-ligand derived structure enhances the conductivity and the reaction mechanism dominated by pseudo-capacitance effect, which significantly improves the rate performance and reversible capacity of the potassium ion battery; in addition, the material can also be applied to lithium ion batteries, and has wide application potential. The present application solves the two problems of insufficient performance (low capacity, slow diffusion, poor cycle) and production bottleneck (high cost, complex process) of WS2-based anode materials by precise control of low-temperature synthesis process and heterostructure design.

[0053] Finally, it should be pointed out that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A WO x @WS2 metal-ligand composite material prepared by a method comprising, The 2-methylimidazole ethanol solution is prepared by adding 2.0-3.0 g of 2-methylimidazole to 10-20 mL of ethanol; the tungsten source is tungsten hexachloride, and the ethanol solution of the tungsten source is prepared by adding 1.9-2.5 g of tungsten hexachloride to 10-20 mL of ethanol. The WO is obtained by adding an ethanol solution of 2-methylimidazole into an ethanol solution of a tungsten source, stirring the reaction, solvent thermal reaction, washing, vacuum drying, and heat treatment. x The WO is obtained by adding an ethanol solution of 2-methylimidazole into an ethanol solution of a tungsten source, stirring the reaction, solvent thermal reaction, washing, vacuum drying, and heat treatment. x The WO is obtained by adding an ethanol solution of 2-methylimidazole into an ethanol solution of a tungsten source, stirring the reaction, solvent thermal reaction, washing, vacuum drying, and heat treatment. x @WS2 metal-ligand composite material; the value of x is in the range of 2≤x≤3.

2. The WO of claim 1 x @Method for producing a WS2 metal-ligand composite material, characterized by, The stirring speed of the stirring reaction is 300-500 r / min, and the time is 20-40 min.

3. The WO of claim 1 x @Method for producing a WS2 metal-ligand composite material, characterized by, During the stirring reaction, 1 mL of the 2-methylimidazole ethanol solution is added to the ethanol solution of the tungsten source each time until the addition is completed. The conditions of the solvothermal reaction include: reacting at 150-200 ℃ for 1-3 h.

4. The WO of claim 1 x @Method for producing a WS2 metal-ligand composite material, characterized by, The conditions of the washing include: alternately washing 2-5 times with deionized water and anhydrous ethanol.

5. The WO of claim 1 x @A method for producing a WS2 metal-ligand composite material, characterized by, The conditions of the heat treatment include: heat treating at 500-800 ℃ for 1-3 h in an inert gas environment.

6. The WO of claim 1 x @Method for producing a WS2 metal-ligand composite material, characterized by, The mass ratio of the WOx to thioacetamide is (150-300):(500-800).

7. The WO of claim 1 x @Method for producing a WS2 metal-ligand composite material, characterized by, ​ 8. The WO of claim 1 x @Method for producing a WS2 metal-ligand composite material, characterized by, The conditions of the sulfidation reaction include: WO x The product is collected after the small porcelain boat is placed in a large porcelain boat containing thioacetamide and is sulfidized at 300-500 °C for 1-3 h under an inert gas environment.

9. A WO x @WS2 metal-ligand composite material prepared by the method of claim 1, wherein the metal-ligand composite material comprises: The WO x The WO x The WO metal-ligand composite material comprises tungsten oxide flower balls, WO2 nanorods grown on the tungsten oxide flower balls, and WS2 covering the surface of the WO2 nanorods; the interlayer spacing of the WS2 sheet crystal face is 0.66 nm.

10. The WO of any one of claims 1-8 x @Method for preparing WS2 metal-ligand composite x @Use of WS2 metal-ligand composite in preparing lithium ion battery

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