Preparation method and application of nitrogen-doped carbon-coated manganese oxide heterojunction composite material
By preparing nitrogen-doped carbon-coated Mn2O3/MnO heterojunction composite materials, the problems of low conductivity and poor cycle stability of lithium-ion battery anode materials were solved, and a simple and controllable preparation process and efficient lithium storage performance were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUNAN INSTITUTE OF SCIENCE AND TECHNOLOGY
- Filing Date
- 2024-02-01
- Publication Date
- 2026-07-31
AI Technical Summary
Existing lithium-ion battery anode materials, such as manganese-based oxides, suffer from problems such as low conductivity, slow reaction kinetics, and poor cycle stability. Furthermore, existing heterojunction fabrication processes are complex, costly, and have poor controllability, making it difficult to achieve large-scale applications.
Mn3O4/C3N4 mixture was prepared by mechanically grinding inorganic manganese salt and urea, then ultrasonically dispersed, and small molecule monomers and initiators were added to carry out polymerization reaction and calcined at high temperature under nitrogen atmosphere to form nitrogen-doped carbon-coated Mn2O3/MnO heterojunction.
A nitrogen-doped carbon-coated manganese oxide heterojunction composite material with a simple and highly controllable preparation process was achieved, which can be prepared in large quantities and exhibits excellent lithium storage performance and cycle stability.
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Figure CN117985764B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of manganese oxide composite materials technology, and in particular to a method for preparing a nitrogen-doped carbon-coated manganese oxide heterojunction composite material and its application in the negative electrode of a lithium-ion battery. Background Technology
[0002] Against the backdrop of energy crisis and environmental pollution, vigorously developing and utilizing renewable and clean energy sources such as wind and solar power is particularly important. However, these sources suffer from volatility, intermittency, and randomness. Developing advanced energy storage and conversion equipment is considered a viable path to improve the utilization efficiency of these renewable energy sources. Lithium-ion batteries have achieved success in the electronics market due to their low cost, good stability, and lack of memory effect. Nevertheless, commercial graphite has a relatively low theoretical specific capacity (only 372 mAh g / g). –1 The current technology is increasingly unable to meet people's demand and desire for high-energy-density energy storage devices. Therefore, the development and application of high-capacity new anode materials is of great significance to the development of lithium-ion batteries.
[0003] Manganese-based oxides are considered potential replacements for graphite anodes due to their high theoretical specific capacity, low cost, abundant reserves, and environmental friendliness. However, low conductivity, slow reaction kinetics, and poor cycle stability significantly limit their large-scale application. To address these issues, constructing heterojunctions has proven to be an effective strategy for improving the electrochemical performance of materials. Studies have found that the construction of heterojunctions can regulate the electronic structure and physicochemical properties of the heterojunction interface in composite materials. On the one hand, based on the built-in electric field formed at the heterojunction interface, electron transfer and ion transport rates are significantly enhanced, potentially accelerating the reaction kinetics of the material. Simultaneously, the strong interactions between heterojunctions can suppress the growth of intermediate products, thus potentially enhancing the cycle stability of the material. Furthermore, the construction of partial heterojunctions can also promote the transformation of semiconductors into conductors, thereby significantly enhancing the conductivity of the material.
[0004] The above analysis shows that heterojunction composite materials have potential applications in the field of lithium-ion battery anodes.
[0005] Patent CN 117374262A discloses an intrinsic heterojunction anode material, its preparation method, and its application. The preparation method involves adding an alkaline solution dropwise to a solution containing a crosslinking agent, graphene oxide, and a FeTiO3 precursor with a three-dimensional network structure. After static aging, the solution is dried, and then the dried product is reduced and sintered. Utilizing the oxygen-containing functional groups in GO and the reducing atmosphere, a phase transition is induced through redox synergy, thereby constructing an intrinsic FeTiO3@Fe2TiO5 heterojunction.
[0006] However, it has the following drawbacks: high raw material cost, complex preparation process, and difficulty in large-scale preparation; at the same time, the coating effect of graphene oxide on heterojunction is not good, and non-metallic doping is not achieved, resulting in unsatisfactory improvement on the electrochemical performance of the material; the formation of heterojunction is mainly achieved through the combined action of oxygen-containing functional groups of graphene oxide and reducing atmosphere, and the preparation process of heterojunction is not very controllable.
[0007] Patent CN 113571674 A discloses a method for preparing and applying an in-situ carbon-coated binary transition metal oxide heterojunction bowl-shaped nanocomposite material, which includes the following steps: First, using manganese acetate tetrahydrate and trimesic acid as reaction raw materials and polyvinylpyrrolidone as surfactant, a precursor powder of the carbon-coated binary transition metal oxide heterojunction bowl-shaped nanocomposite material is prepared by liquid-phase reaction and liquid flow rate control. Then, it is calcined in an argon atmosphere to obtain a bowl-shaped in-situ carbon-coated binary transition metal oxide heterojunction nanocomposite material.
[0008] However, it has the following drawbacks: the preparation process is complex, requiring the use of special equipment such as peristaltic pumps, and irreversibly consuming large amounts of organic solvents and surfactants; the nitrogen doping source of the carbon support in the composite material is unknown, the overall morphology is irregular (as shown in Figure 6), the preparation of heterojunctions has poor controllability, the metal oxide heterojunction particles are large, and the lithium storage specific capacity of the composite material is low (around 20 mAg). –1 At low current density, the specific capacity during the first charge cycle is only 325mAh g. –1 ).
[0009] Therefore, providing a simple and controllable preparation method for nitrogen-doped carbon-coated manganese oxide heterojunction composite materials and their application in lithium-ion battery anodes has become a worthy research topic. Summary of the Invention
[0010] The purpose of this invention is to provide a method for preparing nitrogen-doped carbon-coated manganese oxide heterojunction composite materials for use in lithium-ion battery anode materials. This method has the advantages of simple preparation process, strong controllability, and large-scale preparation.
[0011] The objective of this invention is achieved as follows: A method for preparing a nitrogen-doped carbon-coated manganese oxide heterojunction composite material includes the following steps: Step (1) Weigh 0.3-3.0g of inorganic manganese salt and 5.0-30.0g of urea, and calcine them in air at 550℃ for 2h to obtain Mn3O4 powder and C3N4 powder; Step (2) Place the Mn3O4 powder and C3N4 powder obtained in step (1) in a mortar at a mass ratio of 1:1 to 1:5 and grind them mechanically for 0.5 to 1.0 h to obtain the Mn3O4 / C3N4 mixture precursor. Step (3) The Mn3O4 / C3N4 mixture precursor obtained in step (2) is ultrasonically dispersed in deionized water, and then nitrogen-containing small molecule monomers, 12mol / L HCl solution and initiator are added in sequence, and the mixture is stirred at 0-2℃ for 10-24h. During the reaction, the small molecule monomers can be initiated to polymerize into nitrogen-containing polymers and coat the inner and outer surfaces of the Mn3O4 / C3N4 mixture. Step (4) The reaction solution obtained in step (3) is centrifuged and washed with deionized water and ethanol 3 to 5 times. After vacuum drying, a black solid powder is obtained. Step (5) The black solid powder obtained in step (4) is placed in a nitrogen atmosphere and heated to 700-900℃ at a rate of 1-10℃ / min. After constant-temperature calcination for 1-3 hours, nitrogen-doped carbon-coated manganese oxide heterojunction composite material is finally obtained. During the high-temperature pyrolysis process, Mn3O4 in direct contact with nitrogen-containing polymers can be reduced to MnO, while Mn3O4 partially coated by C3N4 will be converted into Mn2O3. The two work together to form Mn2O3 / MnO heterojunction.
[0012] The inorganic manganese salt is one of manganese chloride, manganese acetate, manganese sulfate, and manganese nitrate.
[0013] The nitrogen-containing small molecule monomer is one of pyrrole, aniline, indole, and dopamine.
[0014] The initiator is one of ferric chloride, ammonium persulfate, hydrogen peroxide, and potassium dichromate.
[0015] In step (3), the amount of deionized water used is 100-200 mL, the amount of nitrogen-containing small molecule monomer used is 0.1-1.0 mL, the amount of 12 mol / L HCl solution used is 5-20 mL, and the amount of initiator used is 1.0-5.0 g.
[0016] An application of a nitrogen-doped carbon-coated manganese oxide heterojunction composite material as a negative electrode material for lithium-ion batteries.
[0017] The beneficial effects of this invention are: (1) The preparation process of the present invention is simple, highly controllable, and can achieve large-scale preparation; (2) The nitrogen-doped carbon-coated manganese oxide heterojunction composite material prepared by the present invention has successfully achieved efficient nitrogen doping of carbon carrier, successful synthesis of quantum dot heterojunction and in-situ coating of nitrogen-doped carbon; when the composite material is used as a negative electrode of lithium-ion battery, it can exhibit excellent lithium storage performance. Attached Figure Description
[0018] Figure 1 The images show scanning electron microscope (a), transmission electron microscope (b), high-resolution transmission electron microscope (c), and scanning transmission electron microscope (d) images of the nitrogen-doped carbon-coated Mn2O3 / MnO heterojunction (Mn2O3 / MnO@NC) composite material prepared in Example 1 of this invention, along with their corresponding elemental distribution diagrams (e–h). Figure 2 The images show the X-ray diffraction pattern (a), Raman spectrum (b), X-ray photoelectron spectrum (c), and high-resolution spectrum (d) of Mn2O3 / MnO@NC composite material prepared in Example 1 of this invention. Figure 3 This is a cycle performance diagram of the Mn2O3 / MnO@NC composite negative electrode prepared in Example 1 of this invention; Figure 4 This is a rate performance diagram of the Mn2O3 / MnO@NC composite anode prepared in Example 1 of this invention; Figure 5 This is a scanning electron microscope image of the Mn2O3 / MnO@NC–1 composite material prepared in Example 2 of this invention; Figure 6 The images show the X-ray diffraction pattern (a), Raman spectrum (b), X-ray photoelectron spectrum (c), and high-resolution spectrum (d) of Mn2O3 / MnO@NC–1 composite material prepared in Example 2 of this invention. Figure 7 This is a cycle performance diagram of the Mn2O3 / MnO@NC–1 composite negative electrode prepared in Example 2 of this invention; Figure 8 This is a rate performance diagram of the Mn2O3 / MnO@NC–1 composite anode prepared in Example 2 of this invention. Detailed Implementation
[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0020] Example 1:
[0021] First, 510 mg of manganese chloride and 10 g of urea were placed in a muffle furnace and calcined at 550 °C for 2 h in air to obtain Mn3O4 and C3N4 powders. Mn3O4 (200 mg) and C3N4 (400 mg) were weighed at a 1:2 mass ratio and transferred to a mortar for thorough mechanical grinding. The resulting Mn3O4 / C3N4 mixture powder was used as a precursor and ultrasonically dispersed in 135 mL of deionized water. Then, 0.27 mL of pyrrole, 9 mL of 12 mol / L hydrochloric acid, and 2.7 g of (NH4)2S2O8 were added sequentially. The mixture was reacted thoroughly at 0 °C with stirring for 12 h. After centrifugation, the powder was washed twice with deionized water and twice with ethanol, dried to obtain a black powder, and calcined at 750 °C in a nitrogen atmosphere for 2 h to finally obtain the Mn2O3 / MnO@NC composite material.
[0022] See Figure 1 Figure 1 shows the scanning electron microscope (SEM) image (a), transmission electron microscope (TEM) image (b), high-resolution transmission electron microscope (HRTEM) image (c), and scanning transmission electron microscope (SEM) image (d) of the prepared Mn2O3 / MnO@NC composite material, along with their corresponding elemental distribution maps (e–h). Figure 1 shows that the composite material possesses a typical open porous network framework. Figure 2 shows that the composite material contains abundant quantum dots (10–20 nm), and these quantum dots are mainly composed of Mn2O3 / MnO heterostructures. Figure 3 shows the microscopic distribution of the Mn2O3 / MnO heterostructure. Figures 4–h show that N atoms were successfully incorporated into the carbon support, and the carbon support achieved in-situ encapsulation of quantum dot-type Mn2O3 / MnO heterostructures.
[0023] See Figure 2 The figures show the X-ray diffraction pattern (a), Raman spectrum (b), X-ray photoelectron spectroscopy (c), and high-resolution spectrum (d) of Mn2O3 / MnO@NC composite material. As shown in Figure (a), the prepared Mn2O3 / MnO@NC composite material contains crystalline Mn2O3 and MnO. As shown in Figure (b), the ratio of the D-band to the G-band intensity of the composite material is approximately 1.14, indicating that the carbon support in the material has a high defect degree. As shown in Figure (c), the composite material simultaneously contains C, N, O, and Mn elements, with the N element content reaching as high as 20.1%, confirming the efficient nitrogen doping of the carbon support. As shown in Figure (d), the peaks corresponding to binding energies of 640.8 eV and 651.9 eV correspond to Mn. 2+ The peaks at 644.2 eV and 653.5 eV correspond to Mn. 3+ This indicates the successful synthesis of Mn2O3 / MnO heterojunctions.
[0024] See Figure 3The figure shows the cycling performance of the prepared Mn2O3 / MnO@NC composite anode. As can be seen from the figure, at a current density of 0.2 A g... –1 Under the specified conditions, the Mn2O3 / MnO@NC composite anode still exhibits a capacity of 1402.5 mAh g after 300 cycles. –1 High reversible specific capacity.
[0025] See Figure 4 The figure shows the rate performance of the prepared Mn2O3 / MnO@NC composite anode. As can be seen from the figure, the Mn2O3 / MnO@NC electrode achieves a rate performance of [missing information - likely a specific value] at a current density of 0.1 A g. –1 The hourly discharge specific capacity is 954.6 mAh g. –1 And when the current density increases to 1.6 A g –1 At that time, the capacity value was still as high as 659.2 mAh g. –1 This indicates its excellent rate performance.
[0026] Example 2: First, 700 mg of manganese chloride and 15 g of urea were placed in a muffle furnace and calcined at 550 °C for 2 h in air to prepare Mn3O4 and C3N4 powders. Mn3O4 (200 mg) and C3N4 (200 mg) were weighed at a 1:1 mass ratio and transferred to a mortar for thorough mechanical grinding. The resulting Mn3O4 / C3N4 mixture powder was used as a precursor and ultrasonically dispersed in 150 mL of deionized water. Then, 0.27 mL of pyrrole, 9 mL of 12 mol / L hydrochloric acid, and 2.7 g of (NH4)2S2O8 were added sequentially. The mixture was reacted thoroughly at 2 °C for 14 h with stirring. After centrifugation, the powder was washed three times with deionized water and three times with ethanol, dried to obtain a black powder, and calcined at 750 °C in a nitrogen atmosphere for 2 h to finally obtain the Mn2O3 / MnO@NC–1 composite material.
[0027] See Figure 5 The figure shows a scanning electron microscope (SEM) image of the prepared Mn2O3 / MnO@NC–1 composite material. As shown, the Mn2O3 / MnO@NC–1 composite material exhibits an open porous structure similar to that of Mn2O3 / MnO@NC.
[0028] See Figure 6The figures show the X-ray diffraction pattern (a), Raman spectrum (b), overall X-ray photoelectron spectrum (c), and high-resolution spectrum (d) of Mn2p of the prepared Mn2O3 / MnO@NC–1 composite material. As shown in Figure (a), the prepared Mn2O3 / MnO@NC–1 composite material contains crystalline Mn2O3 and MnO. As shown in Figure (b), the ratio of D-band to G-band intensity of the composite material is approximately 1.06, indicating a high defect rate in the carbon support on the surface material. As shown in Figure (c), the composite material simultaneously contains C, N, O, and Mn elements, with N content reaching as high as 14.4%, confirming the efficient nitrogen doping of the carbon support. As shown in Figure (d), the peaks corresponding to binding energies of 640.9 eV and 651.9 eV correspond to Mn. 2+ The peaks at 644.2 eV and 653.5 eV correspond to Mn. 3+ This indicates the successful synthesis of Mn2O3 / MnO heterojunctions.
[0029] See Figure 7 The figure shows the cycling performance of the prepared Mn2O3 / MnO@NC–1 composite anode. As can be seen from the figure, at a current density of 0.2 A g… –1 Under the specified conditions, the Mn2O3 / MnO@NC–1 composite anode still exhibited a capacity of 989.8 mAh g after 300 cycles. –1 High reversible specific capacity.
[0030] See Figure 8 The figure shows the rate performance of the prepared Mn2O3 / MnO@NC–1 composite anode. As can be seen from the figure, the Mn2O3 / MnO@NC–1 electrode achieves a rate performance of [missing information - likely a specific value] at a current density of 0.1 Ag. –1 The hourly discharge specific capacity is 823.7 mAh g. –1 And when the current density increases to 1.6 A g –1 At that time, the capacity value remained at 503.4 mAh g. –1 This indicates its excellent rate performance.
Claims
1. A method for preparing a nitrogen-doped carbon-coated manganese oxide heterojunction composite material, characterized in that: Includes the following steps: Step (1) Weigh 0.3 ~ 3.0 g of inorganic manganese salt and 5.0 ~ 30.0 g of urea, and calcine them in air at 550 ℃ for 2 h to obtain Mn3O4 powder and C3N4 powder; The inorganic manganese salt is one of manganese chloride, manganese acetate, manganese sulfate and manganese nitrate; Step (2) Place the Mn3O4 powder and C3N4 powder obtained in step (1) in a mortar at a mass ratio of 1:1 to 1:5 and grind them mechanically for 0.5 to 1.0 h to obtain a Mn3O4 / C3N4 mixture precursor; Step (3) The Mn3O4 / C3N4 mixture precursor obtained in step (2) is ultrasonically dispersed in deionized water, followed by the sequential addition of a nitrogen-containing small molecule monomer, a 12 mol / L HCl solution and an initiator, and the mixture is stirred and reacted at 0 ~ 2 ℃ for 10 ~ 24 h; the nitrogen-containing small molecule monomer is one of pyrrole, aniline, indole and dopamine; Step (4) The reaction solution obtained in step (3) is centrifuged and washed with deionized water and ethanol 3 to 5 times. After vacuum drying, a black solid powder is obtained. Step (5) The black solid powder obtained in step (4) is placed in a nitrogen atmosphere and heated to 700-900 ℃ at a rate of 1-10 ℃ / min. After constant temperature calcination for 1-3 h, nitrogen-doped carbon-coated manganese oxide heterojunction composite material is finally obtained.
2. The method for preparing a nitrogen-doped carbon-coated manganese oxide heterojunction composite material according to claim 1, characterized in that: The initiator is one of ferric chloride, ammonium persulfate, hydrogen peroxide, and potassium dichromate.
3. The method for preparing a nitrogen-doped carbon-coated manganese oxide heterojunction composite material according to claim 1, characterized in that: In step (3), the amount of deionized water used is 100-200 mL, the amount of nitrogen-containing small molecule monomer used is 0.1-1.0 mL, the amount of 12 mol / L HCl solution used is 5-20 mL, and the amount of initiator used is 1.0-5.0 g.
4. The application of the nitrogen-doped carbon-coated manganese oxide heterojunction composite material prepared by the method described in claim 1, characterized in that: It is used as a negative electrode material for lithium-ion batteries.