Preparation, modification and application of hexagonal cobalt telluride / carbon composite material

Abstract

The application relates to preparation, modification and application of a hexagonal cobalt telluride / carbon composite material, and belongs to the technical field of potassium ion batteries. Hexagonal cobalt telluride Co 1.67 Te2 / NC is used in the energy storage field for the first time, has a large interlayer spacing and certain tellurium vacancies, and is in-situ grown on a stacked flaky carbon base. The application also modifies the above Co 1.67 Te2 / NC, introduces graphene to interact with a precursor, and prepares Co 1.67 Te2 / NC / rGO composite material, new phase Co 1.67 Te2 is uniformly distributed on closely combined nitrogen-doped carbon and reduced graphene. The application also relates to application of the above two composite materials in negative electrode materials of potassium ion batteries. The composite material has a large specific surface area and rich mesoporous structures, is beneficial to full soaking of electrolyte and full exposure of active sites, and realizes fast, stable and high-capacity potassium storage under a higher load.

Description

Technical Field

[0001] This invention belongs to the field of potassium-ion battery technology, specifically relating to the preparation, modification, and application of a hexagonal cobalt telluride / carbon composite material. Background Technology

[0002] In recent years, with the increasing energy demand from electric vehicles and grid-scale applications, efforts have been focused on developing next-generation electrochemical energy storage devices that are low-cost, possess excellent rate performance, and long cycle life. Potassium-ion batteries are considered a competitive alternative to lithium-ion batteries in future electrochemical energy storage systems due to the widespread availability of potassium resources and their low cost. However, due to the large Kg... + Ionic radius (K) + vs.Li + , Potassium-ion batteries face several challenges in selecting anode materials, such as relatively high ion diffusion resistance and large volume changes during charge and discharge, leading to rapid capacity decay and poor structural stability. Therefore, research on anode materials that can maintain a robust structure under high-current, long-cycle conditions has attracted widespread attention.

[0003] Compared to traditional oxides and sulfoselenides, metal tellurides based on conversion reaction mechanisms possess higher conductivity and density, which is crucial for improving rate performance and volumetric capacity. As a typical metal telluride, cobalt ditelluride has attracted widespread attention in the field of energy storage and conversion due to its unique metallic properties, polymorphism, catalytic activity, and magnetism. However, similar to other conversion-type anode materials, cobalt ditelluride also faces challenges such as poor conductivity and large volume changes during cycling, requiring targeted and effective solutions.

[0004] Existing research indicates that combining nanoscale cobalt ditelluride with conductive carbon materials (such as carbon fibers, graphene nanosheets, and Mxene) can improve their performance, suppress volume expansion, and enhance electron transport, thereby achieving stable and rapid ion storage. However, current research primarily focuses on orthorhombic CoTe2 and hexagonal Co. 1.11 Te2, so far, has not been studied for hexagonal Co 1.67 Te2 anodes are being studied extensively in the energy storage field. Furthermore, using thicker electrodes to load more active material is one effective way to improve battery energy density; however, the loading of active material in existing studies is typically between 0.5 and 1.2 mg / cm³. -2 There has been relatively little research on higher load capacities. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to prepare a Co material that maintains a robust structure even under high current and long-term cycling conditions. 1.67 Te2 anode material, and still has excellent electrochemical performance under high load conditions.

[0006] On the one hand, the present invention provides a hexagonal cobalt telluride / carbon composite material Co 1.67 The preparation method of Te2 / NC specifically includes the following steps:

[0007] 1) Preparation of the precursor Co-PDA:

[0008] S1. Dissolve cobalt chloride hexahydrate CoCl2·6H2O in a mixed solvent of deionized water and anhydrous ethanol, and dissolve dopamine (DA) in deionized water;

[0009] S2. After adjusting the pH to weakly alkaline by adding ammonia to the CoCl2·6H2O solution, add it dropwise to the DA solution while stirring continuously to obtain a mixture;

[0010] S3. The resulting mixture is heated in an oil bath to induce the polymerization of DA and react with Co. 2+ Coordination yields the precursor Co-PDA;

[0011] 2) Co 1.67 Preparation of Te2 / NC:

[0012] S1. In a tube furnace, the precursor and Te powder are placed in downstream and upstream crucibles respectively for tellurization to obtain telluride;

[0013] S2. The telluride is placed in a tube furnace for secondary calcination to obtain Co. 1.67 Te2 / NC composite material.

[0014] in:

[0015] In step 1)S1, the mass ratio of CoCl2·6H2O to DA is 1:(0.5~2.5); the mixed solvent is prepared by deionized water and ethanol in a volume ratio of 2:1; the mass concentration of the CoCl2·6H2O solution is 0.024g / mL, and the mass concentration of the DA solution is 0.017~0.85g / mL.

[0016] In step 1)S2, the pH is 7.3 to 7.8.

[0017] In step 1)S3, the oil bath heating temperature of the mixture is 60-80℃, and the reaction time is 12-24h.

[0018] In step 2)S1, the outer diameter of the tube furnace is 30-50 mm; the mass ratio of Co-PDA to Te powder is 1:(2-4), the particle size of Te powder is 100 mesh; the tellurization temperature is 500-700℃, the tellurization time is 2-4 h, and the heating rate is 2-5℃ / min.

[0019] In step 2)S2, the prepared telluride needs to be placed in a porcelain boat and sealed with aluminum foil during the second calcination. The second calcination temperature is 500-700℃, the calcination time is 2-4h, and the heating rate is 5-10℃ / min.

[0020] On the other hand, this invention introduces a small amount of graphene oxide (GO) to interact with Co-PDA, followed by tellurization and secondary calcination, to obtain a hexagonal cobalt telluride / double carbon composite material Co with superior potassium storage performance. 1.67 Te2 / NC / rGO specifically includes the following steps:

[0021] (1) Preparation of composite precursor:

[0022] S1. Weigh out GO powder, disperse it in distilled water to prepare a GO suspension, and weigh out Co. 1.67 Step 1) The Co-PDA obtained in S3 is dissolved in distilled water to prepare a Co-PDA solution;

[0023] S2. Sonicate the dispersion until the solution becomes clear;

[0024] S3. The suspension is added dropwise to the Co-PDA solution under continuous sonication, and the sonication is continued to obtain a mixed solution;

[0025] S4. Freeze the mixed solution and then dry it using a freeze dryer to obtain the composite precursor;

[0026] (2) Co 1.67 Synthesis of Te2 / NC / rGO composite materials (refer to Co) 1.67 Preparation of Te2 / NC.

[0027] in:

[0028] In step (1)S1, the mass ratio of Co-PDA to GO is (10-30):1; the mass concentration of the GO suspension is 1 mg / mL, and the mass concentration of the Co-PDA solution is 6.67 mg / mL.

[0029] In step (1) S2, the ultrasonic treatment time is 3 to 6 hours.

[0030] In step (1) S3, the volume ratio of the added suspension to the Co-PDA solution is (0.22~0.67):1; the ultrasonic time is 2~4h.

[0031] In step (1) S4, the freezing time is 8 to 24 hours, and the drying time using a freeze dryer is 8 to 12 hours.

[0032] Furthermore, the present invention also relates to the Co. 1.67 Te2 / NC and Co 1.67 The loading of Te2 / NC / rGO composite materials ranged from 0.7 to 1.4 mg / cm³. -2 Application of high loading of composite materials in potassium-ion battery anode materials.

[0033] Compared with the prior art, the present invention has obvious advantages and beneficial effects:

[0034] (1) Secondary calcination plays a key role in this invention, as it can induce the traditional hexagonal Co phase through aluminothermic reduction. 1.11 Te2 towards novel hexagonal Co 1.67 The Te2 transformation, accompanied by the generation of tellurium vacancies and increased interlayer spacing in the new phase, further enhances electron and ion conduction, resulting in excellent high-current cycling stability as a potassium ion anode material.

[0035] (2) In this invention, the composite precursor, namely graphene, interacts with the functional groups of Co-PDA. After tellurization and secondary calcination, PDA is converted into nitrogen-doped carbon, and graphene is reduced. The two forms of carbon are tightly bound together to form the new phase Co. 1.67 Te2 coating not only improves conductivity but also buffers volume changes during high-current charging and discharging, enabling rapid and stable potassium storage.

[0036] (3) Co prepared by the present invention 1.67 Te2 / NC and Co 1.67 The Te2 / NC / rGO composite material has a large specific surface area and abundant mesoporous structure, which is conducive to the full wetting of electrolyte and the full exposure of active sites, thus enabling higher capacity potassium storage.

[0037] (4) The active material loading of the coated electrode of the present invention can reach 1.4 mg / cm³. -2 This will help improve the energy density of batteries.

[0038] (5) The present invention is simple to operate, has strong repeatability, and is conducive to mass production.

[0039] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0040] Figure 1 Co prepared in Example 1 1.67 X-ray diffraction pattern of Te2 / NC material;

[0041] Figure 2 Co prepared in Example 1 1.67 Raman spectra of Te2 / NC materials;

[0042] Figure 3 Co prepared in Example 1 1.67 Scanning electron microscope (SEM) images of Te2 / NC materials; wherein, Figure (a) is an SEM image of the material prepared in Example 1, with a magnification of 30,000x; Figure (b) is an SEM image of the material prepared in Example 1, with a magnification of 10,000x;

[0043] Figure 4 Co prepared in Example 1 1.67 Nitrogen adsorption-desorption isotherms and pore size distribution curves of Te2 / NC materials;

[0044] Figure 5 Co prepared in Example 1 1.67 When Te2 / NC is used as an anode material in potassium-ion batteries, it reaches 0.5Ag. -1 Cyclic performance curves at current densities;

[0045] Figure 6 The Co prepared in Examples 2, 3, and 4 1.67 X-ray diffraction pattern of Te2 / NC / rGO composite material;

[0046] Figure 7 The Co prepared in Examples 2, 3, and 4 1.67 Raman spectra of Te2 / NC / rGO composite material;

[0047] Figure 8 The Co prepared in Examples 2, 3, and 4 1.67Scanning electron microscope (SEM) images of the Te2 / NC / rGO composite material; wherein, Figure (a) is an SEM image of the material prepared in Example 2, with a magnification of 30,000x; Figure (b) is an SEM image of the material prepared in Example 2, with a magnification of 10,000x; Figure (c) is an SEM image of the material prepared in Example 3, with a magnification of 30,000x; Figure (d) is an SEM image of the material prepared in Example 3, with a magnification of 10,000x; Figure (e) is an SEM image of the material prepared in Example 4, with a magnification of 30,000x; Figure (f) is an SEM image of the material prepared in Example 4, with a magnification of 10,000x;

[0048] Figure 9 The Co prepared in Examples 2, 3, and 4 1.67 Nitrogen adsorption-desorption isotherms and pore size distribution curves of Te2 / NC materials; wherein, Figure (a) is the adsorption-desorption isotherm and Figure (b) is the pore size distribution curve.

[0049] Figure 10 The Co prepared in Examples 2, 3, and 4 1.67 The Te2 / NC / rGO composite material has a loading capacity of 1.3–1.4 mg / cm³ as a negative electrode material for potassium-ion batteries. -2 At 0.5Ag -1 Cyclic performance curves at current densities;

[0050] Figure 11 Co prepared in Example 5 1.67 The Te2 / NC / rGO-10 loading is ~1.4 mg cm⁻¹ -2 When used as a negative electrode material in potassium-ion batteries, it has a content of 0.5 Ag. -1 Cyclic performance curves at current densities;

[0051] Figure 12 The Co prepared in Examples 2, 3, and 4 1.67 Rate performance of Te2 / NC / rGO composite material under low load;

[0052] Figure 13 Co prepared in Comparative Example 1 1.67 X-ray diffraction pattern and scanning electron microscope image of Te2 / NC / rGO composite material, and its performance as a potassium-ion battery anode material at 0.5 Ag. -1 The cycling performance curves at current densities are shown in Figure 1; where Figure 1(a) is the X-ray diffraction pattern, Figure 1(b) is the scanning electron microscope image, and Figure 1(c) is the cycling performance curve.

[0053] Figure 14 Co prepared in Comparative Example 21.11 X-ray diffraction pattern of Te2 / NC and its application as a negative electrode material in potassium-ion batteries at 0.5 Ag. -1 The cycling performance curves at current densities are shown in Figure (a), which is the X-ray diffraction pattern, and Figure (b) is the cycling performance curve. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] This invention does not impose any special restrictions on the source of any of the raw materials used; they can be commercially available or homemade. There are no special restrictions on their purity; the conventional purity required for preparing lithium batteries is sufficient.

[0056] The novel hexagonal Co prepared in this invention 1.67 The large interlayer spacing and tellurium vacancies in Te2 further enhance electron and ion conduction. Further modification yields Co. 1.67 In Te2 / NC / rGO composites, the new phase Co 1.67 Te2 has a size of approximately 100±20 nm and is uniformly distributed on tightly bonded nitrogen-doped carbon and reduced graphene. This not only improves the conductivity but also buffers the volume changes during high-current charging and discharging. In addition, the composite material has a large specific surface area and abundant mesoporous structure, which is conducive to the full wetting of the electrolyte and the full exposure of active sites. This enables rapid, stable, and high-capacity potassium storage under higher loads.

[0057] The following detailed description uses specific examples:

[0058] Example 1

[0059] A hexagonal cobalt telluride / carbon composite material Co 1.67 The preparation method of Te2 / NC anode material specifically includes the following steps:

[0060] (1) Preparation of precursor Co-PDA:

[0061] S1. Dissolve 1g of CoCl2·6H2O in a mixed solvent of 30mL deionized water and 15mL ethanol, and dissolve 0.5g of DA in 30mL deionized water;

[0062] S2. Adjust the pH to 7.5 by adding ammonia to the CoCl2·6H2O solution, then add it dropwise to the DA solution while stirring continuously to obtain a mixture;

[0063] S3. The resulting mixture was heated in an oil bath at 70°C for 12 hours to induce the polymerization of DA and react with Co. 2+ Fully coordinated, the precursor Co-PDA is obtained.

[0064] (2) Co 1.67 Preparation of Te2 / NC:

[0065] S1. In a tube furnace with a diameter of 40 mm, the precursor and 100-mesh Te powder were placed in the downstream and upstream crucibles respectively at a mass ratio of 1:2 for tellurization. The reaction temperature was 600℃, the tellurization time was 2h, and the heating rate was 2℃ / min to obtain telluride.

[0066] S2. The telluride prepared above was placed in a porcelain boat, covered with aluminum foil, and placed in a tube furnace for secondary calcination. The calcination temperature and time were 600℃ and 2h, respectively, with a heating rate of 5℃ / min, to obtain Co. 1.67 Te2 / NC composite material;

[0067] (3) The aforementioned material was used as the negative electrode material for potassium-ion batteries, and the loading of active material on the coated electrode was controlled at ~1.4 mg / cm³ using a coating technique. -2 The potassium-ion batteries were assembled using battery packaging technology, and their electrochemical performance was tested.

[0068] The Co obtained in this embodiment 1.67 X-ray diffraction pattern of Te2 / NC as follows Figure 1 As shown, phase analysis confirms that the obtained material is cobalt ditelluride, which is similar to standard Co. 1.67 The Te2 (PDF#97-004-4736) phase is consistent with that of other impurities. Additionally, Co... 1.67 The Raman spectrum of Te2 / NC is as follows Figure 2 As shown in the figure, the material contains D-bands and G-bands, and the peak intensity ratio of the D-band to the G-band is 0.82, which confirms the presence of carbon in the material and that the degree of graphitization is relatively high, which is beneficial to improving conductivity.

[0069] The Co obtained in this application 1.67 Scanning electron microscope images of Te2 / NC are shown below. Figure 3 As shown, where Figure 3 (a) is a scanning electron microscope image magnified 30,000 times. Figure 3 (b) is a scanning electron microscope image magnified 10,000 times, showing hexagonal / cubic Co particles with a size of approximately 100 ± 20 nm.1.67 Te2 particles are grown in situ on a stacked sheet-like carbon substrate and are randomly distributed. Figure 4 The corresponding nitrogen adsorption-desorption isotherms and pore size distribution curves show that it has a mesoporous structure and a large specific surface area of ​​approximately 160.5 cm². 3 g -1 .

[0070] The obtained Co 1.67 When Te2 / NC composite materials are used as anode materials for potassium-ion batteries, their cycle performance is as follows: Figure 5 As shown, at 0.5Ag -1 After 100 cycles at a current density, it exhibits high capacity retention, with a discharge specific capacity of 308.7 mAh g. -1 It then gradually decays, and after 650 cycles, the discharge specific capacity remains at 172 mAh g. -1 Therefore, it can be seen that the new phase Co obtained in this embodiment... 1.67 Te2 / NC exhibits good electrochemical performance in potassium-ion batteries, but there is still room for further modification.

[0071] Example 2

[0072] A hexagonal cobalt telluride / double carbon composite material Co 1.67 Te2 / NC / rGO(Co 1.67 The preparation method of Te2 / NC / rGO-15 specifically includes the following steps:

[0073] (1) Preparation of the composite precursor Co-PDA-15:

[0074] S1. Co-PDA was prepared using the same steps as in Example 1. Then, 0.2 g of the Co-PDA was weighed and dissolved in 30 mL of distilled water to prepare a Co-PDA solution with a mass concentration of 6.67 mg / mL. 50 mg of GO powder was weighed and dispersed in 50 mL of distilled water to prepare a GO suspension with a mass concentration of 1 mg / mL.

[0075] S2. Sonicate the dispersion for 3 hours until the solution becomes clear;

[0076] S3. Add 13.3 mL of GO suspension dropwise to Co-PDA solution under continuous sonication, and continue sonication for 2 h to obtain a mixed solution;

[0077] S4. Freeze the mixed solution for 8 hours, and then dry it using a freeze dryer for 8 hours to obtain the composite precursor;

[0078] (2) Co 1.67 Te2 / NC / rGO composite material (Co) 1.67Preparation of Te2 / NC / rGO-15):

[0079] S1. In a tube furnace with an outer diameter of 40 mm, the precursor and 100-mesh Te powder were placed in the downstream and upstream crucibles respectively at a mass ratio of 1:2 for tellurization. The tellurization temperature was 600℃, the tellurization time was 2 h, and the heating rate was 2℃ / min; telluride was obtained.

[0080] S2. The telluride prepared above was placed in a porcelain boat, covered with aluminum foil, and placed in a tube furnace for secondary calcination. The calcination temperature and time were 600℃ and 2h, respectively, with a heating rate of 5℃ / min, to obtain Co. 1.67 Te2 / NC / rGO-15 composite material;

[0081] (3) The aforementioned material was used as the negative electrode material for a potassium-ion battery. The loading of the active material on the coated electrode was controlled at ~1.3 mg / cm³ using a coating technique. -2 The potassium-ion batteries were assembled using battery packaging technology, and their electrochemical performance was tested.

[0082] The Co obtained in this embodiment 1.67 The X-ray diffraction pattern, Raman spectrum, scanning electron microscope image, nitrogen adsorption-desorption isotherm and pore size distribution curve, and cycling performance diagram of Te2 / NC / rGO-15 are shown below. Figure 6 , Figure 7 , Figure 8 (a)(b) Figure 9 and Figure 10 As shown, where Figure 9 (a) is the adsorption-desorption isotherm. Figure 9 (b) shows the aperture distribution curve, and the specific analysis can be found in Example 4.

[0083] Example 3

[0084] A hexagonal cobalt telluride / double carbon composite material Co 1.67 Te2 / NC / rGO(Co 1.67 The preparation method of Te2 / NC / rGO-20 specifically includes the following steps:

[0085] (1) Preparation of the composite precursor Co-PDA-20: The preparation of Co-PDA-20 includes the synthesis of the precursor Co-PDA and its complexation with GO:

[0086] S1. Co-PDA was prepared using the same steps as in Example 1. Then, 0.2 g of the Co-PDA was weighed and dissolved in 30 mL of distilled water to prepare a Co-PDA solution with a mass concentration of 6.67 mg / mL. 50 mg of GO powder was weighed and dispersed in 50 mL of distilled water to prepare a GO suspension with a mass concentration of 1 mg / mL.

[0087] S2. Sonicate the dispersion for 3 hours until the solution becomes clear;

[0088] S3. Add 10 mL of GO suspension dropwise to Co-PDA solution under continuous sonication, and continue sonication for 2 h to obtain a mixed solution;

[0089] S4. Freeze the mixed solution for 8 hours, and then dry it using a freeze dryer for 8 hours to obtain the composite precursor;

[0090] (2) Co 1.67 Te2 / NC / rGO composite material (Co) 1.67 Preparation of Te2 / NC / rGO-20:

[0091] S1. In a tube furnace with an outer diameter of 40 mm, the precursor and 100-mesh Te powder were placed in the downstream and upstream crucibles respectively at a mass ratio of 1:2 for tellurization. The tellurization temperature was 600℃, the tellurization time was 2 h, and the heating rate was 2℃ / min; telluride was obtained.

[0092] S2. The telluride prepared above was placed in a porcelain boat, covered with aluminum foil, and placed in a tube furnace for secondary calcination. The calcination temperature and time were 600℃ and 2h, respectively, with a heating rate of 5℃ / min, to obtain Co. 1.67 Te2 / NC / rGO-20 composite material;

[0093] (3) The aforementioned material was used as the negative electrode material for potassium-ion batteries, and the loading of active material on the coated electrode was controlled at ~1.4 mg / cm³ using a coating technique. -2 The potassium-ion batteries were assembled using battery packaging technology, and their electrochemical performance was tested.

[0094] The Co obtained in this embodiment 1.67 The X-ray diffraction pattern, Raman spectrum, scanning electron microscope image, nitrogen adsorption-desorption isotherm and pore size distribution curve, and cycling performance diagram of Te2 / NC / rGO-20 are shown below. Figure 6 , Figure 7 , Figure 8 (c)(d) Figure 9 and Figure 10 As shown, see Example 4 for a detailed analysis.

[0095] Example 4

[0096] A hexagonal cobalt telluride / double carbon composite material Co 1.67 Te2 / NC / rGO(Co 1.67 The preparation method of Te2 / NC / rGO-20 specifically includes the following steps:

[0097] (1) Preparation of the composite precursor Co-PDA-25:

[0098] S1. Co-PDA was prepared using the same steps as in Example 1. Then, 0.2 g of the Co-PDA was weighed and dissolved in 30 mL of distilled water to prepare a Co-PDA solution with a mass concentration of 6.67 mg / mL. 50 mg of GO powder was weighed and dispersed in 50 mL of distilled water to prepare a GO suspension with a mass concentration of 1 mg / mL.

[0099] S2. Sonicate the dispersion for 3 hours until the solution becomes clear;

[0100] S3. Add 8 mL of GO suspension dropwise to Co-PDA solution under continuous sonication, and continue sonication for 2 h to obtain a mixed solution;

[0101] S4. Freeze the mixed solution for 8 hours, and then dry it using a freeze dryer for 8 hours to obtain the composite precursor;

[0102] (2) Co 1.67 Te2 / NC / rGO composite material (Co) 1.67 Preparation of Te2 / NC / rGO-25):

[0103] S1. In a tube furnace with an outer diameter of 40 mm, the precursor and 100-mesh Te powder were placed in the downstream and upstream crucibles respectively at a mass ratio of 1:2 for tellurization. The tellurization temperature was 600℃, the tellurization time was 2 h, and the heating rate was 2℃ / min; telluride was obtained.

[0104] S2. The telluride prepared above was placed in a porcelain boat, covered with aluminum foil, and placed in a tube furnace for secondary calcination. The calcination temperature and time were 600℃ and 2h, respectively, with a heating rate of 5℃ / min, to obtain Co. 1.67 Te2 / NC / rGO-25 composite material;

[0105] (3) The aforementioned material was used as the negative electrode material for potassium-ion batteries, and the loading of active material on the coated electrode was controlled at ~1.4 mg / cm³ using a coating technique. -2 The potassium-ion batteries were assembled using battery packaging technology, and their electrochemical performance was tested.

[0106] The Co obtained in this embodiment 1.67The X-ray diffraction pattern, Raman spectrum, scanning electron microscope image, nitrogen adsorption-desorption isotherm and pore size distribution curve, and cycling performance diagram of Te2 / NC / rGO-25 are shown below. Figure 6 , Figure 7 , Figure 8 (e)(f), Figure 9 and Figure 10 As shown. Examples 2, 3, and 4 will be analyzed together here. As... Figure 6 As shown, the obtained Co 1.67 The Te2 / NC / rGO composite material is entirely composed of cobalt ditelluride phase, which is similar to standard Co. 1.67 Te2 (PDF#97-004-4736) phase is consistent with the original phase, with no other impurities. From Figure 7 Co can be seen from 1.67 Both Te2 / NC / rGO composites contain D-bands and G-bands, and Co... 1.67 Te2 / NC / rGO-15, Co 1.67 Te2 / NC / rGO-20, Co 1.67 The peak intensity ratios of the D and G bands of Te2 / NC / rGO-25 were 0.88, 0.98, and 0.92, respectively, confirming the presence of carbon in the material. This is in contrast to Co. 1.67 The Te2 / NC phase has an increased amount of amorphous carbon, which provides more potassium storage sites.

[0107] Co obtained in Examples 2-4 1.67 Scanning electron microscope image of Te2 / NC / rGO composite material as shown below Figure 8 As shown in the figure, when GO is added, Co 1.67 Te2 / NC is uniformly dispersed on the rGO surface, while Co... 1.67 Te2 / NC / rGO-15, Co 1.67 In Te2 / NC / rGO-20, due to the relatively large mass of GO, the wrinkled structure of rGO is clearly visible, and the addition of graphene further alleviates volume expansion. Furthermore, Figure 9 Showcasing Co 1.67 Te2 / NC / rGO-15, Co 1.67 Te2 / NC / rGO-20, and Co 1.67 The specific surface areas of Te2 / NC / rGO-25 are approximately 251.95, 273.65, and 170.88 m², respectively. 2 g -1 The pore size is mainly distributed in the range of 3–12 nm. Compared to Co... 1.67 Te2 / NC phase, Co 1.67The specific surface area of ​​the Te2 / NC / rGO composite material is further increased, which is conducive to the full penetration of electrolyte and the maximization of potassium storage sites.

[0108] The obtained Co 1.67 When Te2 / NC / rGO composite materials are used as anode materials in potassium-ion batteries, their cycle performance is as follows: Figure 10 As shown, at 0.5Ag -1 After 650 cycles at a current density, it still maintains a high specific capacity, Co 1.67 Te2 / NC / rGO-15, Co 1.67 Te2 / NC / rGO-20, and Co 1.67 The discharge specific capacities of Te2 / NC / rGO-25 are 246.4, 271, and 283.7 mAh g, respectively. -1 Compared to Co 1.67 The Te2 / NC phase ratio is much higher. This shows that the modification effect after adding graphene is significant, as demonstrated by the Co obtained in Examples 2, 3, and 4. 1.67 The Te2 / NC / rGO composite material exhibits excellent potassium storage performance.

[0109] Example 5

[0110] A hexagonal cobalt telluride / double carbon composite material Co 1.67 Te2 / NC / rGO(Co 1.67 The preparation method of Te2 / NC / rGO-10 specifically includes the following steps:

[0111] (1) Preparation of the composite precursor Co-PDA-10:

[0112] S1. Co-PDA was prepared using the same steps as in Example 1. Then, 0.2 g of the Co-PDA was weighed and dissolved in 30 mL of distilled water to prepare a Co-PDA solution with a mass concentration of 6.67 mg / mL. 50 mg of GO powder was weighed and dispersed in 50 mL of distilled water to prepare a GO suspension with a mass concentration of 1 mg / mL.

[0113] S2. Sonicate the dispersion for 3 hours until the solution becomes clear;

[0114] S3. Add 20 mL of GO suspension dropwise to Co-PDA solution under continuous sonication, and continue sonication for 2 h to obtain a mixed solution;

[0115] S4. Freeze the mixed solution for 8 hours, and then dry it using a freeze dryer for 8 hours to obtain the composite precursor;

[0116] (2) Co 1.67Te2 / NC / rGO composite material (Co) 1.67 Preparation of Te2 / NC / rGO-10):

[0117] S1. In a tube furnace with an outer diameter of 40 mm, the precursor and 100-mesh Te powder were placed in the downstream and upstream crucibles respectively at a mass ratio of 1:2 for tellurization. The tellurization temperature was 600℃, the tellurization time was 2 h, and the heating rate was 2℃ / min; telluride was obtained.

[0118] S2. The telluride prepared above was placed in a porcelain boat, covered with aluminum foil, and placed in a tube furnace for secondary calcination. The calcination temperature and time were 600℃ and 2h, respectively, with a heating rate of 5℃ / min, to obtain Co. 1.67 Te2 / NC / rGO-10 composite material;

[0119] (3) The aforementioned material was used as the negative electrode material for potassium-ion batteries, and the loading of active material on the coated electrode was controlled at ~1.4 mg / cm³ using a coating technique. -2 The potassium-ion batteries were assembled using battery packaging technology, and their electrochemical performance was tested.

[0120] The obtained Co 1.67 When Te2 / NC / rGO composite materials are used as anode materials in potassium-ion batteries, their cycle performance is as follows: Figure 11 As shown, at 0.5A g -1 After 500 cycles at a current density, it still retains 171.7 mAh g. -1 The specific capacity was lower than that of Examples 2, 3, and 4, therefore the amount of graphene added should not be excessive.

[0121] Example 6

[0122] Steps (1) and (2) are the same as in Example 2, except that the active substance loading in step (3) is controlled at ~0.7 mg / cm³. -2 .

[0123] Example 7

[0124] Steps (1) and (2) are the same as in Example 3, except that the active substance loading in step (3) is controlled at ~0.6 mg / cm³. -2 .

[0125] Example 8

[0126] Steps (1) and (2) are the same as in Example 4, except that the active substance loading in step (3) is controlled at ~0.9 mg / cm³. -2 .

[0127] The obtained Co1.67 When Te2 / NC / rGO composite materials are used as anode materials for potassium-ion batteries, their rate performance is as follows: Figure 12 As shown, Co 1.67 Te2 / NC / rGO-15, Co 1.67 Te2 / NC / rGO-20, and Co 1.67 Te2 / NC / rGO-25 at concentrations of 0.05, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 Ag -1 The discharge specific capacity corresponding to the current density is shown in Table 1, with 3.0 Ag as an example. -1 Taking the current density as an example, the corresponding discharge specific capacities are 264.1, 300.9, and 232.0 mA hg, respectively. -1 When the current density returns to 0.05 A g -1 If this cycle is repeated 5 times, the capacity can be restored to 451.7, 468.2, and 424.0 mA hg. -1 Therefore, it can be seen that the Co obtained in Examples 2, 3, and 4 1.67 The Te2 / NC / rGO composite material exhibits excellent potassium storage performance under low load.

[0128] Table 1. Discharge specific capacity at different current densities.

[0129]

[0130] Comparative Example 1

[0131] (1) Preparation of the composite precursor (Co-PDA-20): The preparation of Co-PDA-20 includes the synthesis of the precursor Co-PDA and its complexation with GO. First, Co-PDA was prepared using the same steps as in Example 1, with 0.2 g weighed and dissolved in 30 mL of distilled water; then, a GO suspension with a concentration of 1 mg / mL was prepared. 50 mg of GO powder was weighed and dispersed in 50 mL of distilled water, and the dispersion was sonicated for 3 h until the solution became clear. Subsequently, 10 mL of the GO suspension was added dropwise to the above Co-PDA solution under continuous sonication, and sonication was continued for 2 h. The mixed solution was frozen and then dried using a freeze dryer for 8 h to finally obtain the composite precursor.

[0132] (2) Co 1.11 Te2 / NC / rGO composite material (Co) 1.11 Preparation of Te2 / NC / rGO-20): One-step tellurization: In a tube furnace with a diameter of 40 mm, the precursor and Te powder were placed in downstream and upstream crucibles respectively at a mass ratio of 1:2 for tellurization. The reaction temperature was 600℃ and the reaction time was 2 h to obtain Co. 1.67Te2 / NC / rGO-20 composite material;

[0133] (3) The aforementioned material was used as the negative electrode material for a potassium-ion battery. The loading of the active material on the coated electrode was controlled at ~1.0 mg / cm³ using a coating technique. -2 The potassium-ion batteries were assembled using battery packaging technology, and their electrochemical performance was tested.

[0134] Co obtained in this comparative example 1.11 The X-ray diffraction pattern, scanning electron microscope image, and cycling performance of Te2 / NC / rGO-20 are shown below. Figure 13 As shown in (a), (b), and (c), phase analysis confirms that the obtained material is cobalt ditelluride, which is similar to standard Co. 1.11 It is consistent with Te2 (PDF#97-004-4737) and has no other impurities. Furthermore, its morphological characteristics are similar to Co. 1.67 Similar to Te2 / NC / rGO-20, Co 1.11 Te2 / NC is uniformly dispersed on the rGO surface. The resulting Co... 1.11 When Te2 / NC / rGO-20 is used as a negative electrode material for potassium-ion batteries, at 0.5A g... -1 After 100 cycles at a current density, its discharge specific capacity is only 155.4 mA hg. -1 After 400 cycles, the discharge specific capacity remained at 168.5 mA hg. -1 Compared to Co 1.67 Te2 / NC / rGO-20 exhibits poor potassium storage performance, indicating that secondary sintering induces the formation of a new Co phase. 1.67 Te2 generation is essential for rapid, stable, and high-capacity potassium storage.

[0135] Comparative Example 2

[0136] (1) Preparation of the precursor (Co-PDA): 1 g of CoCl2·6H2O and 0.5 g of DA were dissolved in a mixed solvent of 30 mL deionized water and 15 mL ethanol, respectively, and 30 mL of deionized water. Ammonia was added to the CoCl2·6H2O solution to adjust the pH to 7.4, and this solution was added dropwise to the DA solution with constant stirring. Subsequently, the resulting mixture was heated in an oil bath at 70 °C for 12 h to induce the polymerization of DA and react with Co. 2+ Fully coordinated.

[0137] (2) Co 1.11Preparation of Te2 / Co / NC: In a coarse-tube furnace with a diameter of 80 mm, the precursor and Te powder were placed in downstream and upstream crucibles respectively at a mass ratio of 1:2 for tellurization at a reaction temperature of 600℃ for 2 h. Then, the prepared telluride was placed in a porcelain boat, covered with aluminum foil, and placed in a tube furnace for secondary calcination at 600℃ for 2 h to obtain Co. 1.67 Te2 / NC composite material;

[0138] (3) The aforementioned material was used as the negative electrode material for a potassium-ion battery. The loading of the active material on the coated electrode was controlled at ~1.2 mg / cm³ using a coating technique. -2 The potassium-ion batteries were assembled using battery packaging technology, and their electrochemical performance was tested.

[0139] Co obtained in this comparative example 1.11 X-ray diffraction patterns of Te2 / Co / NC, and cycling performance as follows: Figure 14 As shown in (a) and (b), phase analysis confirmed that the obtained material is cobalt ditelluride and metallic cobalt phase, which is consistent with standard Co. 1.11 The Te2 (PDF#97-004-4737) and Co (PDF#97-005-2935) phases were consistent, with no other impurity phases. This result indicates that using a furnace tube with a large outer diameter cannot achieve sufficient tellurization of Co-PDA, resulting in the formation of residual cobalt. The obtained Co... 1.11 When Te2 / Co / NC is used as an anode material for potassium-ion batteries, at 0.5Ag... -1 After 250 cycles at a current density, its discharge specific capacity is only 152.4 mAh g. -1 This shows that incomplete tellurization, due to its higher proportion of inactive substances, is not conducive to high-capacity potassium storage, further demonstrating the superiority of complete tellurization combined with secondary sintering.

[0140] Comparative Examples 1 and 2 exhibit lower capacity and poorer cycle performance compared to the potassium-ion batteries assembled in Examples 1, 2, 3, and 4. The purpose of Comparative Example 1 is to highlight the novel Co phase induced by secondary sintering in this invention. 1.67 Te2 generation compared to traditional Co 1.11 Te2 enables rapid, stable, and high-capacity potassium storage. Comparative Example 2 aims to highlight the necessity of using furnace tubes with small outer diameters in this invention to achieve full tellurization of Co-PDA. The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hexagonal cobalt telluride / carbon composite material Co 1.67 The method for preparing Te2 / NC is characterized by, Specifically including The following steps: 1) Preparation of the precursor Co-PDA: S1. Dissolve cobalt chloride hexahydrate in a mixed solvent of deionized water and anhydrous ethanol, and dissolve dopamine in deionized water; The mass ratio of cobalt chloride hexahydrate to dopamine is 1:(0.5~2.5); S2. After adjusting the pH to weakly alkaline by adding ammonia to the cobalt chloride hexahydrate solution, add it dropwise to the dopamine solution while stirring continuously to obtain a mixture; S3. The resulting mixture is heated in an oil bath to induce the polymerization of DA and react with Co. 2+ Coordination yields the precursor Co-PDA; 2) Co 1.67 Preparation of Te2 / NC: S1. In a tube furnace, the precursor and Te powder are placed in downstream and upstream crucibles respectively for tellurization to obtain telluride; The mass ratio of Co-PDA to Te powder is 1:(2~4); S2. The telluride is placed in a tube furnace for secondary calcination to obtain Co. 1.67 Te2 / NC composite material; During the secondary calcination, the prepared telluride needs to be encapsulated in aluminum foil; the secondary calcination temperature is 500~700 ℃, the calcination time is 2~4 h, and the heating rate is 5~10 ℃ / min.

2. The hexagonal cobalt telluride / carbon composite material Co according to claim 1 1.67 The method for preparing Te2 / NC is characterized by, In step 1) S1, the mixed solvent is prepared by mixing deionized water and ethanol in a volume ratio of 2:1; the mass concentration of the cobalt chloride hexahydrate solution is 0.024 g / mL, and the mass concentration of the dopamine solution is 0.017~0.85 g / mL; In step 1) S2, the pH is 7.3~7.8; In step 1) S3, the oil bath heating temperature of the mixture is 60~80 ℃, and the reaction time is 12~24 h.

3. The hexagonal cobalt telluride / carbon composite material Co according to claim 1 1.67 The method for preparing Te2 / NC is characterized by, In step 2) S1, the outer diameter of the tube furnace is 30~50 mm, the particle size of the Te powder is 100 mesh, the tellurization temperature is 500~700 ℃, the tellurization time is 2~4 h, and the heating rate is 2~5 ℃ / min.

4. A hexagonal cobalt telluride / double carbon composite material Co 1.67 The method for preparing Te2 / NC / rGO is characterized by, Specifically, the following steps are included: (1) Preparation of composite precursor: S1. Weigh graphene oxide powder, disperse it in distilled water, and prepare a graphene oxide suspension. Weigh the Co-PDA obtained in step 1) S3 of claim 1, dissolve it in distilled water, and prepare a Co-PDA solution. The mass ratio of Co-PDA to graphene oxide is (10~30):1; S2. The graphene oxide suspension is subjected to ultrasonic treatment until the solution becomes clear; S3. The ultrasonicated graphene oxide suspension is added dropwise to the Co-PDA solution under continuous ultrasonication, and ultrasonic treatment is continued to obtain a mixed solution; S4. Freeze the mixed solution and then dry it using a freeze dryer to obtain the composite precursor; (2) Co 1.67 Preparation of Te2 / NC / rGO composite material: S1. In a tube furnace, the composite precursor and Te powder are placed in downstream and upstream crucibles respectively for tellurization to obtain telluride; The mass ratio of the composite precursor to Te powder is 1:(2~4). S2. The telluride is placed in a tube furnace for secondary calcination to obtain Co. 1.67 Te2 / NC / rGO composite material; During the secondary calcination, the prepared telluride needs to be encapsulated in aluminum foil; the secondary calcination temperature is 500~700 ℃, the calcination time is 2~4 h, and the heating rate is 5~10 ℃ / min.

5. The hexagonal cobalt telluride / double carbon composite material Co according to claim 4 1.67 The method for preparing Te2 / NC / rGO is characterized by, In step (1) S1, the concentration of the graphene oxide suspension is 1 mg / mL and the concentration of the Co-PDA solution is 6.67 mg / mL. In step (1) S2, the ultrasonic treatment time is 3~6 h; In step (1) S3, the volume ratio of the added suspension to the Co-PDA solution is (0.22~0.67):1; the ultrasonic time is 2~4 h; In step (1) S4, the freezing time is 8~24 h and the drying time using a freeze dryer is 8~12 h.

6. A hexagonal cobalt telluride / carbon composite material Co 1.67 Te2 / NC, characterized in that, It is prepared by the preparation method according to any one of claims 1-3.

7. A hexagonal cobalt telluride / double carbon composite material Co 1.67 Te2 / NC / rGO, characterized in that, It is prepared by the preparation method according to any one of claims 4-5.

8. The Co as described in claim 6 1.67 Te2 / NC composite material or Co as described in claim 7 1.67 The application of Te2 / NC / rGO composite material in potassium-ion battery anode materials is characterized by... The Co 1.67 Te2 / NC composite material or Co 1.67 The loading of the Te2 / NC / rGO composite material ranged from 0.7 to 1.4 mg / cm³. -2 Within the range.

9. The application according to claim 8, characterized in that, The Co 1.67 Te2 / NC composite material at 0.5 A g -1 The current density and 1.4 mg cm⁻¹ -2 Under a load of 650 cycles, the discharge specific capacity is ≥150 mA hg -1 The Co 1.67 Te2 / NC / rGO composite material at 0.5 A g -1 The current density and 1.3~1.4 mg cm⁻¹ -2 Under a load of 650 cycles, the discharge specific capacity is ≥240 mA hg -1 .

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