Preparation method and application of metal monatomic anchored Bi (at) C electrode material

Abstract

The invention discloses a preparation method of a metal monatomic anchored Bi (at) C electrode material and application of the metal monatomic anchored Bi (at) C electrode material as a sodium ion battery anode, and the preparation method comprises the following steps: mixing Bi (NO3) 3.5 H2O, Cu (NO3) 2.3 H2O, trimesic acid and methanol, and heating at high temperature in a reaction kettle to obtain a Cu / Bi-MOF metal organic framework precursor; and carrying out high-temperature reaction on the precursor in a tubular furnace under the protection of a nitrogen atmosphere, carbonizing the organic part of the MOF framework, and anchoring the Cu element on the carbon framework in a monatomic form to obtain the Bi (at) SA Cu-C electrode material. The electrode material is used for a sodium ion battery anode, the stable structure of a carbon framework obtained after MOF pyrolysis and the catalytic effect assistance of monatomic are integrated, the material has good rate capability and high cycling stability, and feasible guidance is provided for application of monatomic catalysis in the field of sodium ion batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode materials for sodium ion batteries, and in particular to a preparation method and application of a metal single atom anchored Bi@C electrode material. Background Art

[0002] As a typical representative of energy storage materials, lithium-ion batteries are of great significance in the field of power batteries. The contradiction between the rapid growth in demand for lithium-ion batteries and the shortage of lithium resources and rising costs has prompted researchers to continuously look for possible alternatives. Metallic sodium and metallic lithium are in the same main group and have many similar properties. More importantly, it has lower costs and more abundant reserves (the content in the earth's crust is about 2.64%), and is considered to be one of the most ideal metals to replace lithium. Among them, since the formation energy of Na and graphite to form a compound is positive, while other alkali metals are negative, indicating that Na-graphite compounds are thermodynamically unstable, the currently widely used lithium-ion battery graphite negative electrode is not suitable for sodium-ion batteries, and a more suitable negative electrode material needs to be found.

[0003] As anode materials with application prospects in sodium-ion batteries, carbonaceous materials, metal oxides, metal sulfides and alloy-based anode materials have been developed. Among these developed negative electrode materials, alloy-based materials have higher specific capacity, initial coulombic efficiency and faster response speed. Despite their obvious advantages, they still have problems of low conductivity, slow kinetic reaction and large volume expansion during the sodium ion insertion / deinsertion process, resulting in short cycle life and low rate performance.

[0004] Single atom catalysts (SACs) have been a hot research topic in the field of catalysis in recent years. SACs have unique electronic effects and highly stable structures. Their complete atomic utilization and influence on diffusion dynamics provide more advantages for catalytic effects. On the other hand, because single atoms are captured by defect sites, the material can still maintain stable coordination even under high temperature and high pressure conditions. Metal organic frameworks (MOFs) have been widely studied due to their designable framework structure, high surface area, adjustable shape and porosity. It is relatively easy to prepare energy storage materials with stable structures using MOF as a precursor derivative. Therefore, using MOF as a precursor and utilizing the unique coordination environment and electronic effects of metal atoms in MOF materials to prepare single atom anchored electrode materials is expected to improve the shortcomings of alloy-type anode materials. Summary of the invention

[0005] In order to solve the technical problems mentioned in the above background technology, an innovative preparation method and application of a metal single atom anchored Bi@C electrode material are proposed. The synthesis route is clear and simple, the cost is low, and it is suitable for the battery field. It is an ideal electrode material.

[0006] In order to achieve the above object, the present invention provides a method for preparing a metal single atom anchored Bi@C electrode material, comprising the following steps: Step 1, preparation of Cu / Bi-MOF microrods: First, Bi(NO3)3·5H2O, Cu(NO3)2·3H2O, and trimesic acid are dispersed in methanol solvent, ultrasonically and magnetically stirred for 30 min, then the resulting suspension is poured into a polytetrafluoroethylene-lined autoclave and reacted at 120°C for 24 h; finally, the suspension is centrifuged and washed several times with methanol and anhydrous ethanol, respectively, and dried under vacuum to obtain Cu / Bi-MOF microrods.

[0007] Step 2: Preparation of Bi@SA Cu-C: Take the prepared Cu / Bi-MOF microrods, raise the temperature to a high temperature at a uniform rate and calcine for 2 h in a N2 atmosphere.

[0008] As a further description of the above technical solution: In step 1, the type of copper salt is not limited, including but not limited to one or more of copper nitrate, copper acetate, copper chloride, copper sulfate, etc.

[0009] As a further description of the above technical solution: In the step 1, the molar concentration of Cu(NO3)2·3H2O is 0.1-0.3 mmol / L.

[0010] As a further description of the above technical solution: In the step 1, the high temperature reaction time of the reactor is 12 to 24 hours.

[0011] As a further description of the above technical solution: In the step 2, the temperature of high temperature calcination is 500°C to 800°C.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. In the present invention, MOF derivative materials with metal single atoms anchored were developed, which provided useful guidance for studying the application of single atom catalysis in advanced sodium ion battery electrode materials. Among them, Bi@SA Cu-C anchored by Cu single atoms was prepared by a one-step hydrothermal and carbonization process. The catalytic effect of Cu single atoms on the sodium ion transport kinetics and the regulation of inorganic components in the solid electrolyte membrane formation process were studied, proving that the introduction of Cu single atoms can reduce the migration energy barrier of sodium ions and accelerate the dissociation rate of electrolyte components to promote the generation of more inorganic components.

[0013] 2. In the present invention, the Cu single atom anchored Bi@SA Cu-C electrode material prepared exhibits high specific capacity, rate performance and cycle stability in electrochemical tests, and the material has a first-cycle charge-discharge ratio of 77%. At a current density of 0.2 A / g, the electrode material has a high specific capacity of 404 mAh / g; at a current density of 70.0 A / g, the electrode material also has a specific capacitance of 315 mAh / g, and a rate performance of 78%. Importantly, at a current density of 5.0 A / g, the electrode material was subjected to 6,000 constant current charge-discharge tests, and the capacity retention rate was close to 100%.

[0014] 3. In the present invention, the preparation method is simple and effective, and the construction of the metal single atom anchored electrode material demonstrated can be simply extended to construct other metal single atom anchored MOF derivative electrode materials for energy storage devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The scanning electron microscope image of the Cu / Bi-MOF microrods provided in Example 1 of the present invention is shown; Figure 2 The scanning electron microscope image of Bi@SA Cu-C provided in Example 1 of the present invention is shown; Figure 3 The transmission electron microscope image of Bi@SA Cu-C provided in Example 1 of the present invention under the high-angle annular dark field mode of the spherical aberration electron microscope is shown; Figure 4 The X-ray diffraction refinement diagram of Bi@SA Cu-C provided in Example 1 of the present invention is shown; Figure 5 The electrochemical performance diagram of Bi@SA Cu-C as an electrode material in an ether-based electrolyte provided by Example 1 of the present invention is shown. Figure 5 a is the charge-discharge curve of the first five cycles at a current density of 0.2 A / g. Figure 5 b is the rate performance diagram at different current densities; Figure 6 The graph shows the test results of the cycle stability of Bi@SA Cu-C and Bi@C provided in Example 1 of the present invention as electrode materials at a current density of 5 A / g.

[0016] Figure 7 The electrochemical performance diagram of a full battery prepared with Bi@SA Cu-C as anode and Na3V2(PO4)3@C as cathode according to Example 1 of the present invention is shown. Figure 7 a is the charge-discharge curve of the first five cycles at a current density of 0.1 A / g. Figure 7 b is the rate performance diagram at different current densities; DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0018] See also Figure 1-7 This embodiment provides a preparation method and application of a metal single atom anchored Bi@C electrode material, comprising the following steps: Step 1, preparation of Cu / Bi-MOF microrods: First, add 1 mmol Bi(NO3)3·5H2O, 0.1 mmol Cu(NO3)2·3H2O, and 5 mmol trimesic acid into 60 mL methanol, ultrasonicate and stir for 30 min, and obtain a blue slurry after stirring evenly; secondly, pour the obtained slurry into a 100 ml polytetrafluoroethylene-lined autoclave, react at 120°C for 24 h, cool, wash twice with methanol, then wash twice with ethanol, and then dry at 70°C overnight to obtain light blue Cu / Bi-MOF particles; the scanning electron microscope image is shown in the figure Figure 1 shown.

[0019] Step 2, preparation of Bi@SA Cu-C: 100 mg Cu / Bi-MOF was dispersed in a porcelain boat and calcined at 700 °C for 2 h at a heating rate of 3 °C / min under N2 atmosphere. The final product Bi@SA Cu-C was obtained as Figure 2 As shown, a single atom can be obtained from Figure 3 Observed.

[0020] The X-ray diffraction refinement pattern of Bi@SA Cu-C prepared by the above steps is as follows: Figure 4 shown.

[0021] The prepared Bi@SA Cu-C was used as the negative electrode material for sodium ion batteries, and its electrochemical performance was tested in an ether-based electrolyte solution. Figure 5 and Figure 6 shown. Figure 5 a is the charge and discharge curve at different current densities. Figure 5 b is the rate performance diagram at different current densities.

[0022] The Bi@SA Cu-C prepared above was used as the negative electrode material of sodium ion battery, and its cycle stability was tested in ether-based electrolyte. Figure 6As shown in Figure 2, at a current density of 5.0 A / g, the capacitance retention rate of the electrode material was close to 100% after 6000 cycles of constant current charge and discharge.

[0023] The prepared Bi@SA Cu-C was used as the negative electrode material of the sodium ion battery, and Na3V2(PO4)3@C was used as the positive electrode material. The electrochemical performance of the full battery was tested in an ether-based electrolyte solution. Figure 7 At a current density of 0.1 A / g, the full battery maintains good cycle reversibility, as shown in Figure 7 As shown in a; in the rate performance test at different current densities, it also shows excellent capacity retention rate, such as Figure 7 As shown in b. Example

[0024] Step 1, preparation of Cu / Bi-MOF particles: First, add 1 mmol Bi(NO3)3·5H2O, 0.3 mmol Cu(NO3)2·3H2O, and 5 mmol trimesic acid into 60 mL methanol, ultrasonicate and stir for 30 min, and obtain a blue slurry after stirring evenly; secondly, pour the obtained slurry into a 100 ml polytetrafluoroethylene-lined autoclave, react at 120°C for 24 h, cool, wash twice with methanol, then wash twice with ethanol, and then dry at 70°C overnight to obtain dark blue Cu / Bi-MOF particles; scanning electron microscopy image and Figure 1 similar.

[0025] Step 2, preparation of Cu / Bi@C: 100 mg Cu / Bi-MOF was dispersed in a porcelain boat and calcined at 700 °C for 2 h at a heating rate of 3 °C / min under N2 atmosphere. The final product Cu / Bi@C was Figure 2 Similar, but the particles of the outer layer Bi are coarser.

[0026] Cu / Bi@C exhibits a specific capacity of 385 mAh / g at 0.2 A / g and 217 mAh / g at 70.0 A / g. Example

[0027] Step 1, preparation of Cu / Bi-MOF particles: First, add 1 mmol Bi(NO3)3·5H2O, 0.1 mmol Cu(NO3)2·3H2O, and 5 mmol trimesic acid to 60 mL methanol, ultrasonically stir and stir for 30 min, and obtain a blue slurry after stirring evenly; secondly, pour the obtained slurry into a 100 ml polytetrafluoroethylene-lined autoclave, react at 120°C for 12 h, cool, wash twice with methanol, then wash twice with ethanol, and then dry at 70°C overnight to obtain light blue Cu / Bi-MOF particles; the scanning electron microscope image does not obtain a complete rod-like structure, but a mixture of rod-like structure and sheet structure.

[0028] Step 2: Preparation of Cu / Bi@C: 100 mg of Cu / Bi-MOF was dispersed in a porcelain boat and calcined at 700°C for 2 h at a heating rate of 3°C / min in a N2 atmosphere. The final product Cu / Bi@C retained the morphology of the precursor, and the presence of Cu single atoms could not be detected by spherical aberration electron microscopy.

[0029] Cu / Bi@C exhibits a specific capacity of 332 mAh / g at 0.2 A / g and 157 mAh / g at 70.0 A / g. Example

[0030] Step 1, preparation of Cu / Bi-MOF particles: First, add 1 mmol Bi(NO3)3·5H2O, 0.3 mmol Cu(NO3)2·3H2O, and 5 mmol trimesic acid to 60 mL methanol, ultrasonicate and stir for 30 min, and obtain a blue slurry after stirring evenly; secondly, pour the obtained slurry into a 100 ml polytetrafluoroethylene-lined autoclave, react at 120°C for 24 h, cool, wash twice with methanol, then wash twice with ethanol, and then dry at 70°C overnight to obtain dark blue Cu Bi-MOF particles; scanning electron microscopy image and Figure 1 similar.

[0031] Step 2, preparation of Cu / Bi@C: 100 mg Cu / Bi-MOF was dispersed in a porcelain boat and calcined at 500°C for 2 h at a heating rate of 3°C / min under N2 atmosphere. The final product Cu / Bi@C was Figure 2 Similar, but the presence of Cu single atoms cannot be detected by spherical aberration electron microscopy.

[0032] Cu / Bi@C exhibits a specific capacity of 373 mAh / g at 0.2 A / g and 235 mAh / g at 70.0 A / g.

[0033] In the present invention, MOF derivative materials with metal single atoms anchored were first innovatively developed, which provided useful guidance for studying the application of single atom catalysis in advanced sodium ion battery electrode materials. Among them, Bi@SA Cu-C anchored by Cu single atoms was prepared by a one-step hydrothermal and carbonization process. The catalytic effect of Cu single atoms on the sodium ion transport kinetics and the regulation of inorganic components in the solid electrolyte membrane formation process were studied, proving that the introduction of Cu single atoms can reduce the migration energy barrier of sodium ions and accelerate the dissociation rate of salt components in the electrolyte to promote the generation of more inorganic components.

[0034] Secondly, on the one hand, Bi-MOF is a metal organic framework structure with micrometer scale, high porosity and excellent stability at high temperature. After pyrolysis, the morphology structure can still be retained. After carbonization of the organic framework, the internal Bi element is confined, effectively preventing electrode failure caused by volume expansion; on the other hand, the loaded Cu single atom forms Cu-C coordination with the high-temperature pyrolyzed carbon, providing an extremely stable coordination structure that can cope with high temperature and high pressure reaction environments without coordination stripping. Its catalytic effect on sodium ion transport kinetics can enable the material to obtain higher specific capacity and cycle capacity. Therefore, Bi@SA Cu-C electrode material is very suitable for the battery field and is an ideal electrode material.

[0035] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a metal single atom anchored Bi@C electrode material, characterized in that: The following steps are involved: Step 1, preparation of Cu / Bi-MOF microrods: First, Bi(NO3)3·5H2O, Cu(NO3)2·3H2O, and trimesic acid were dissolved in methanol organic solvent, ultrasonicated and magnetically stirred for 30 min, then the obtained suspension was poured into a polytetrafluoroethylene-lined autoclave and reacted at 120 °C for 24 h; finally, the suspension was centrifugally washed with methanol and anhydrous ethanol for multiple times, and dried under vacuum to obtain Cu / Bi-MOF microrods; Step 2, preparation of Bi@SA Cu-C: Take the prepared Cu / Bi-MOF microrods, uniformly heat to a high temperature environment in a N2 atmosphere and calcine for 2 h, then anneal to room temperature, and collect the black powder as the obtained sample.

2. The method for preparing a metal single atom anchored Bi@C electrode material according to claim 1, characterized in that: In step 1, the copper salt includes but is not limited to one or more of copper nitrate, copper acetate, copper chloride, copper sulfate, etc.

3. The method for preparing a metal single atom anchored Bi@C electrode material according to claim 1, characterized in that: In the step 1, the molar concentration of Cu(NO3)2·3H2O is 0.1-0.3 mmol / L, and the reaction time is 12-36 h.

4. The method for preparing a metal single atom anchored Bi@C electrode material according to claim 1, characterized in that: In the step 2, the carbonization temperature is 500-800°C.

5. Application of the metal single atom anchored Bi@C electrode Bi@SA Cu-C material obtained by the preparation method according to claim 1 as an anode material for sodium ion batteries.

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