A Co2P nanoparticle@Cabron@CNTs composite material and its preparation and application
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG COLLEGE OF SECURITY TECH
- Filing Date
- 2023-09-18
- Publication Date
- 2026-07-24
Smart Images
Figure CN117410461B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of composite material technology, specifically to a Co2P nanoparticle@Cabron@CNTs composite material and its preparation and application. Background Technology
[0002] Lithium-ion batteries, due to their high energy density, long cycle life, environmental friendliness, and small size, have become the mainstream electrochemical energy storage device in the current market. However, with the continuous development of society, traditional lithium-ion batteries face problems such as limited energy density, slow charge and discharge rates, rapid cycle degradation, and insufficient safety, and can no longer meet people's ever-increasing demands for battery performance. Therefore, there is an urgent need to optimize and improve lithium-ion batteries on the market. Positive and negative electrode materials, as two key components of lithium-ion batteries, have become important research directions for improving lithium-ion battery performance through improvement and optimization. However, research on positive electrode materials has reached a bottleneck, while negative electrode materials still have great research potential. Graphite negative electrode materials, commonly used in commercial lithium-ion batteries (theoretical capacity 372 mAh g⁻¹), are... -1 The existing graphite phosphide (Co2P) is no longer sufficient to meet current needs, therefore new anode materials need to be developed to replace graphite. Cobalt phosphide (Co2P) is chosen because of its high theoretical capacity (540 mAh g / g). -1 Co2P is considered a potential anode material for next-generation lithium-ion batteries due to its advantages such as low manufacturing cost, good electronic conductivity, and high stability. However, despite its high theoretical specific capacity, Co2P is prone to pulverization, self-agglomeration, and detachment from the conductive current collector during lithium insertion and extraction, resulting in poor rate performance and cycle performance, which limits its practical application.
[0003] To overcome the aforementioned problems and improve the lithium storage performance of Co2P, nanostructuring of Co2P materials and combining them with various carbon materials has proven to be an effective strategy. However, no reports on Co2P-based lithium-ion battery anode materials have been found in published patents. Research indicates that the morphology of the material and the structure of the carbon substrate with which it is combined are key factors affecting the performance of lithium-ion batteries. Summary of the Invention
[0004] To address the aforementioned technical problems and shortcomings in the field, this invention provides a Co2P nanoparticle@Cabron@CNTs composite material, its preparation, and its application. This application can improve the electrochemical activity and structural stability of Co2P, significantly enhancing its discharge specific capacity, cycle performance, and rate performance. The Co2P nanoparticle@Carbon@CNTs composite material has significant application value as a negative electrode material for lithium-ion batteries, aiming to solve the problems mentioned in the prior art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: A Co2P nanoparticle@Cabron@CNTs composite material and its preparation and application, the composite material comprising multi-walled carbon nanotubes (MWCNTs) as the main supporting structure, amorphous carbon coupled to the multi-walled carbon nanotubes, a large number of carbon tentacles derived from the amorphous carbon, and Co2P nanoparticles tightly attached to the amorphous carbon.
[0006] Preferably, the amorphous carbon is formed by carbonization of a metal-organic framework material (ZIF-67), the Co2P nanoparticles are derived from the phosphating of Co nanoparticles, and the Co2P nanoparticles have a diameter of 20-80 nm, the multi-walled carbon nanotubes have a diameter of 50 nm, the multi-walled carbon nanotubes have a length of 1.5 μm, the amorphous carbon has a thickness of 70 nm, and the derived carbon tentacles have a diameter of 10 nm.
[0007] This invention also provides a method for preparing Co2P nanoparticles@Carbon@CNTs composite materials, comprising the following steps: (1) Multi-walled carbon nanotubes (MWCNTs) were dispersed in concentrated nitric acid (68% by mass) and concentrated sulfuric acid (98% by mass), and dispersed by ultrasonication for 30 minutes. Then, they were heated and stirred in an oil bath, washed several times until neutral and collected. Finally, the product was dried in a 60°C forced-air drying oven to obtain MWCNTs-COOH. (2) Disperse MWCNTs-COOH in anhydrous methanol, add it to polyvinylpyrrolidone, so that MWCNTs-COOH is uniformly dispersed in the solution, then add CoCl2 and 2-methylimidazole in sequence, stir evenly and age to obtain a precursor solution, finally wash the product with methanol and collect it, dry it at 60℃ to obtain the precursor; (3) The precursor was placed in a tube furnace and 5% hydrogen / argon mixed gas was introduced at 700°C and kept at the temperature for 2 hours. The resulting product was subjected to phosphating reaction to obtain Co2P nanoparticles@Carbon@CNTs composite material.
[0008] The principle of the preparation method in this application is as follows: First, hydroxyl groups are introduced onto the surface of carbon nanotubes, and polyvinylpyrrolidone is adsorbed; then, Co is adsorbed by electrostatic interaction forces. 2+ It then coordinates with 2-methylimidazole to form a ZIF-67@CNTs composite material; subsequently, it is heated in a reducing atmosphere to convert Co... 2+ The organic matter in ZIF-67 is reduced to Co nanoparticles, and the organic matter is carbonized into amorphous carbon, which then gives rise to carbon tentacles. Finally, the Co nanoparticles are phosphorized to Co2P to obtain the final product. Among them, CNTs play a role in supporting the reaction and conducting electricity, while carbon tentacles provide a larger specific surface area and conductivity.
[0009] Preferably, in step (1), the volume ratio of concentrated nitric acid to concentrated sulfuric acid in the reaction is 1:2. The molar mass ratio of multi-walled carbon nanotubes, concentrated nitric acid, and concentrated sulfuric acid in the reaction is 2:15:37. The oil bath heating reaction is carried out at 90°C for 3 hours.
[0010] Preferably, in step (2), the ratio of MWCNTs-COOH to anhydrous methanol is 2 mg: 7.5 ml. The mass ratio of MWCNTs-COOH, polyvinylpyrrolidone, CoCl2 and 2-methylimidazole is 1:16:10:33, and the aging conditions are 25°C for 12 hours.
[0011] Preferably, in step (3), the phosphating reaction conditions are as follows: in a tube furnace, 0.1g of the obtained product is placed downstream and 1.5g of sodium hypophosphite is placed upstream, then argon gas is introduced and the furnace is kept at 300°C for 2 hours.
[0012] This invention also provides an application of Co2P nanoparticles@Carbon@CNTs composite material in the field of lithium-ion battery anode materials.
[0013] The specific steps for fabricating the lithium-ion battery negative electrode using the composite material of the present invention are as follows: First, a Co2P nanoparticle@Carbon@CNTs composite material, acetylene black conductive agent, and polyvinylidene fluoride (PVDF) binder with a mass ratio of 8:1:1 were taken respectively.
[0014] Dissolve PVDF in an appropriate amount of 1-methyl-2-pyrrolidone (NMP) and stir until PVDF is completely dissolved to prepare an adhesive solution.
[0015] The uniformly ground Co2P nanoparticles@Carbon@CNTs composite material and acetylene black conductive agent were gradually added to the above PVDF solution, and stirring was continued to ensure uniform mixing of the slurry. This step aims to prepare the active material slurry for the electrode.
[0016] The prepared slurry is evenly coated onto a copper foil disc, which is typically 12 mm in diameter.
[0017] The coated electrode sheet is placed in a vacuum oven and baked at 90°C, then annealed at 150°C to obtain the electrode sheet. This step aims to remove residual solvent and enhance the adhesion and conductivity of the electrode material.
[0018] Finally, the prepared electrode sheets were assembled with lithium metal sheets and a Celgard 2500 separator to form a CR2025 coin cell lithium-ion battery. A dimethyl carbonate (DMC)-ethylene carbonate (EC) mixed solvent containing 1.0 M LiPF6 was used as the electrolyte.
[0019] The prepared lithium-ion batteries were tested for charge-discharge performance and cycle performance using the Xinwei Battery Testing System to evaluate their performance.
[0020] The technical effects and advantages of this invention are as follows: 1. The Co2P nanoparticle@Carbon@CNTs composite material uses multi-walled carbon nanotubes as the main support and ZIF-67 as the precursor for Co2P and amorphous carbon. The preparation method of this invention employs precipitation, carbonization, and oxidation synthesis processes. Based on multi-walled carbon nanotubes and ZIF-67 precursors, the preparation process is simpler and more efficient. This reduces preparation costs and improves the scalability of the preparation.
[0021] 2. The carbon nanotubes in the Co2P nanoparticle@Carbon@CNTs composite material have excellent electrical conductivity and excellent mechanical strength, which not only facilitates electron transport but also provides a robust supporting structure for the material, improving its stability and durability.
[0022] Co2P nanoparticles are attached to amorphous carbon, which effectively encapsulates the Co2P nanoparticles, improving the material's electrical conductivity and structural stability. This advantage enhances the material's cycling performance and also strengthens its performance during high-current charge-discharge processes.
[0023] The carbon tentacles derived from amorphous carbon provide more reactive sites for the material, increasing electron transport channels and improving its electrochemical activity. This helps to increase the specific capacity of the material, thereby enhancing the energy density and performance of the battery.
[0024] Thanks to the optimized design of the composite material, the Co2P nanoparticle@Carbon@CNTs composite exhibits better cycle performance and high-current charge-discharge performance in lithium-ion batteries. This means that the battery has greater stability under long-term use and high power demands. Attached Figure Description
[0025] Figure 1 SEM images of ZIF-67@CNTs prepared in Example 1; Figure 2 SEM image of the Co2P nanoparticles@Carbon@CNTs composite material prepared in Example 1; Figure 3 TEM image of the Co2P nanoparticles@Carbon@CNTs composite material prepared in Example 1; Figure 4 The Co2P nanoparticles@Carbon@CNTs composite material prepared in Example 1 was tested at a current density of 0.5 Ag. -1 Cyclic performance graph; Figure 5 The graph shows the rate performance of the Co2P nanoparticles@Carbon@CNTs composite material prepared in Example 1. Detailed Implementation
[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0027] Example 1 A method for preparing a Co2P nanoparticle@Carbon@CNTs composite material includes the following steps: (1) 0.5g of multi-walled carbon nanotubes (MWCNTs) were dispersed in 20ml of concentrated nitric acid and 40ml of concentrated sulfuric acid. The dispersion was ultrasonically dispersed for 30 minutes, then heated and stirred in an oil bath at 90℃ for 3 hours. The mixture was washed several times until neutral and collected. Finally, the product was dried in a 60℃ forced-air drying oven to obtain MWCNTs-COOH.
[0028] (2) 40 mg of MWCNTs-COOH was dispersed in 100 ml of anhydrous methanol, and 0.64 g of polyvinylpyrrolidone was added to ensure that MWCNTs-COOH was uniformly dispersed in the solution. Then, 0.4 g of CoCl2 and 1.32 g of 2-methylimidazole were added successively, stirred evenly, and aged for 12 hours to obtain the precursor solution. Finally, the product was washed with methanol and collected, and dried at 60 °C to obtain the precursor.
[0029] (3) The precursor was placed in a tube furnace, and a 5% hydrogen / argon mixed gas was introduced and heated to 700°C and held for 2 hours. Finally, 0.1g of the obtained product was placed downstream of the tube furnace and 1.5g of sodium hypophosphite was placed upstream. Then argon gas was introduced and the furnace was held at 300°C for 2 hours to obtain the Co2P nanoparticle@Carbon@CNTs composite material.
[0030] Figure 1 This is a SEM image of ZIF-67@CNTs. Due to the support of multi-walled carbon nanotubes, the synthesized ZIF-67 grows tightly on the multi-walled carbon nanotubes, forming a candied hawthorn-like structure; in addition, the average size of ZIF-67 is about 200 nm. Figure 2 This is a SEM image of the Co2P nanoparticle@Carbon@CNTs composite material. It can be seen that amorphous carbon is coupled to multi-walled carbon nanotubes, and carbon tentacles are derived from the amorphous carbon. Co2P nanoparticles are attached to the amorphous carbon, forming a sea cucumber-like structure. Figure 3 This is a TEM image of the Co2P nanoparticle@Carbon@CNTs composite material. TEM clearly shows that the Co2P nanoparticles have a diameter between 20-80 nm and are uniformly attached to amorphous carbon. Simultaneously, numerous carbon tentacles with a diameter of approximately 10 nm are observed to have formed, creating a large number of electron transport channels. Thermogravimetric analysis indicates that the Co2P mass content is 65%.
[0031] The lithium-ion battery negative electrode was fabricated using the materials described in this embodiment: Co2P nanoparticles@Carbon@CNTs composite material, acetylene black conductive agent, and polyvinylidene fluoride (PVDF) binder were weighed in a mass ratio of 8:1:1. PVDF was dissolved in an appropriate amount of 1-methyl-2-pyrrolidone (NMP) and stirred until completely dissolved. Then, the uniformly ground active material and acetylene black were added to the solution, and stirring was continued to ensure uniform mixing of the slurry. The slurry was then uniformly coated onto a copper foil disc (12 mm in diameter), baked in a vacuum oven at 90°C, and then annealed at 150°C to obtain the electrode sheet.
[0032] The prepared electrode sheet was assembled with a lithium metal sheet and a Celgard 2500 separator into a CR2025 button-type lithium-ion battery. The charge-discharge performance and cycle performance of the lithium-ion battery were tested using a mixed solvent of dimethyl carbonate (DMC) and ethylene carbonate (EC) containing 1.0 M LiPF6 as the electrolyte.
[0033] Figure 4 The Co2P nanoparticle@Carbon@CNTs composite material was prepared at a current density of 0.5 Ag. -1 Cyclic charge-discharge tests were conducted within a voltage range of 3-0.01V. After 100 cycles, it still retained 637.8 mAh g. -1 The discharge specific capacity and capacity retention rate are approximately 95.6%, and the coulombic efficiency remains above 98%, demonstrating good reversibility.
[0034] Figure 5 The rate performance diagram of the Co2P nanoparticle@Carbon@CNTs composite material is shown at current densities of 0.25, 0.5, 1, 2, and 0.25 Ag. -1 The average discharge specific capacities were 704, 680, 569, 382, and 739 mAhg, respectively. -1 It exhibits excellent rate capability, even when the current drops to 0.25Ag. -1 At that time, the discharge capacity can be restored to 739mAhg. -1 It exhibits good reversibility.
[0035] Example 2 (1) 0.5g of multi-walled carbon nanotubes (MWCNTs) were dispersed in 20ml of concentrated nitric acid and 40ml of concentrated sulfuric acid. The dispersion was ultrasonically dispersed for 30 minutes, then heated and stirred in an oil bath at 90℃ for 3 hours. The mixture was washed several times until neutral and collected. Finally, the product was dried in a 60℃ forced-air drying oven to obtain MWCNTs-COOH.
[0036] (2) 40 mg of MWCNTs-COOH was dispersed in 100 ml of anhydrous methanol, and 0.64 g of polyvinylpyrrolidone was added to ensure that MWCNTs-COOH was uniformly dispersed in the solution. Then, 0.4 g of CoCl2 and 1.32 g of 2-methylimidazole were added successively, stirred evenly, and aged for 12 hours to obtain the precursor solution. Finally, the product was washed with methanol and collected, and dried at 60 °C to obtain the precursor.
[0037] (3) The precursor was placed in a tube furnace, heated to 700°C by introducing a 5% hydrogen / argon mixed gas, and held at that temperature for 2 hours. Finally, 0.1g of the obtained product was placed downstream of the tube furnace, and 1.5g of sodium hypophosphite was placed upstream. Argon gas was then introduced, and the temperature was held at 250°C for 2 hours to obtain the Co2P nanoparticles@Carbon@CNTs composite material. The structure of the Co2P nanoparticles@Carbon@CNTs composite material was similar to that in Example 1. The main difference was that the phosphating reaction was incomplete, the Co2P content was reduced, and elemental Co appeared.
[0038] The lithium-ion battery negative electrode was fabricated using the same process as in Example 1, and assembled into a lithium-ion battery with a current density of 0.5 Ag. -1 Cyclic charge-discharge tests were conducted within a voltage range of 3-0.01V. After 100 cycles, it still retained 456mAh g. -1 The discharge specific capacity and capacity retention rate are approximately 93.8%, and the coulombic efficiency remains above 98%, demonstrating good reversibility.
[0039] Example 3 (1) 0.5g of multi-walled carbon nanotubes (MWCNTs) were dispersed in 20ml of concentrated nitric acid and 40ml of concentrated sulfuric acid. The dispersion was ultrasonically dispersed for 30min, then heated and stirred in an oil bath at 90℃ for 3h, washed several times until neutral and collected. Finally, the product was dried in a 60℃ forced-air drying oven to obtain MWCNTs-COOH.
[0040] (2) 40 mg of MWCNTs-COOH was dispersed in 100 ml of anhydrous methanol, and 0.64 g of polyvinylpyrrolidone was added to ensure that MWCNTs-COOH was uniformly dispersed in the solution. Then, 0.4 g of CoCl2 and 1.32 g of 2-methylimidazole were added successively, stirred evenly, and aged for 12 hours to obtain the precursor solution. Finally, the product was washed with methanol and collected, and dried at 60 °C to obtain the precursor.
[0041] (3) The precursor was placed in a tube furnace, and a 5% hydrogen / argon mixed gas was introduced and heated to 700°C and held for 2 hours. Finally, 0.1g of the obtained product was placed downstream of the tube furnace and 1.5g of sodium hypophosphite was placed upstream. Then argon gas was introduced and the furnace was held at 350°C for 2 hours to obtain the Co2P nanoparticle@Carbon@CNTs composite material.
[0042] The structure of the product Co2P nanoparticles@Carbon@CNTs composite material is similar to that of Example 1, the main difference being the increased mass percentage of Co2P. Thermogravimetric analysis showed that the mass content of Co2P was 71%.
[0043] The lithium-ion battery negative electrode was fabricated using the same process as in Example 1, and assembled into a lithium-ion battery with a current density of 0.5 Ag. -1 Cyclic charge-discharge tests were conducted within a voltage range of 3-0.01V. After 100 cycles, it still retained 665.5 mAh / g. -1 The discharge specific capacity and capacity retention rate are approximately 94.3%, and the coulombic efficiency remains above 98%, demonstrating good reversibility.
[0044] The following is a detailed comparison table of the three embodiments, including specific values for Co2P content, discharge specific capacity, capacity retention, and coulombic efficiency, as well as performance evaluations:
[0045] Performance evaluation: Co2P content: The Co2P content of Examples 1 and 3 is relatively high, at 65% and 71% respectively, while the Co2P content of Example 2 is less than 65%. Therefore, Examples 1 and 3 perform better in terms of Co2P content.
[0046] Discharge specific capacity: The discharge specific capacities of Examples 1 and 3 were 637.8 mAh / g and 665.5 mAh / g, respectively, while the discharge specific capacity of Example 2 was lower at 456 mAh / g. Example 3 exhibited the highest discharge specific capacity.
[0047] Capacity retention: Examples 1 and 3 both showed good performance in terms of capacity retention, at 95.6% and 94.3% respectively, while Example 2 had a capacity retention of 93.8%.
[0048] Coulomb efficiency: The coulomb efficiency of all three embodiments remained above 98%, demonstrating good reversibility.
[0049] In summary, Examples 1 and 3 show better performance in terms of Co2P content, discharge specific capacity, and capacity retention, while Example 2, although having a lower Co2P content, still exhibits good coulombic efficiency. The above descriptions are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the technical 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 Co2P nanoparticle@Carbon@CNTs composite material, characterized in that, The composite material includes multi-walled carbon nanotubes (MWCNTs) as the main supporting structure, amorphous carbon coupled to the multi-walled carbon nanotubes, a large number of carbon tentacles derived from the amorphous carbon, and Co2P nanoparticles tightly attached to the amorphous carbon to form a sea cucumber-like structure. The amorphous carbon is formed by carbonization of the metal-organic framework material ZIF-67. The Co2P nanoparticles are derived from the phosphating of Co nanoparticles. The Co2P nanoparticles have a diameter of 20-80 nm, the multi-walled carbon nanotubes have a diameter of 50 nm, the multi-walled carbon nanotubes have a length of 1.5 μm, the amorphous carbon has a thickness of 70 nm, and the derived carbon tentacles have a diameter of 10 nm. ZIF-67 is a precursor of cobalt phosphide and amorphous carbon. Due to the support of multi-walled carbon nanotubes, ZIF-67 grows tightly on multi-walled carbon nanotubes, forming a candied hawthorn-like structure.
2. A method for preparing the Co2P nanoparticle@Carbon@CNTs composite material according to claim 1, characterized in that, Including the following steps: (1) Multi-walled carbon nanotubes (MWCNTs) were dispersed in concentrated nitric acid and concentrated sulfuric acid, and ultrasonically dispersed for 30 minutes. Then, they were heated and stirred in an oil bath, washed several times until neutral and collected. Finally, the product was dried in a 60°C forced-air drying oven to obtain MWCNTs-COOH. (2) Disperse MWCNTs-COOH in anhydrous methanol, add it to polyvinylpyrrolidone, so that MWCNTs-COOH is uniformly dispersed in the solution, then add CoCl2 and 2-methylimidazole in sequence, stir evenly and age to obtain a precursor solution, finally wash the product with methanol and collect it, dry it at 60℃ to obtain the precursor; (3) The precursor was placed in a tube furnace and 5% hydrogen / argon mixed gas was introduced at 700°C and kept at the temperature for 2 hours. The resulting product was subjected to phosphating reaction to obtain Co2P nanoparticles@Carbon@CNTs composite material.
3. The method for preparing the Co2P nanoparticle@Carbon@CNTs composite material according to claim 2, characterized in that, In step (1), the volume ratio of concentrated nitric acid to concentrated sulfuric acid in the reaction is 1:
2.
4. The method for preparing the Co2P nanoparticle@Carbon@CNTs composite material according to claim 2, characterized in that, In step (1), the oil bath heating reaction conditions are 90°C for 3 hours.
5. The method for preparing the Co2P nanoparticle@Carbon@CNTs composite material according to claim 2, characterized in that, In step (2), the ratio of MWCNTs-COOH to anhydrous methanol is 2 mg: 7.5 ml.
6. The method for preparing the Co2P nanoparticle@Carbon@CNTs composite material according to claim 2, characterized in that, In step (2), the mass ratio of MWCNTs-COOH, polyvinylpyrrolidone, CoCl2 and 2-methylimidazole is 1:16:10:33, and the aging conditions are 25°C for 12 hours.
7. The method for preparing the Co2P nanoparticle@Carbon@CNTs composite material according to claim 2, characterized in that, In step (3), the phosphating reaction conditions are as follows: 0.1g of the obtained product is placed downstream in a tube furnace, 1.5g of sodium hypophosphite is placed upstream, and then argon gas is introduced and kept at 300°C for 2 hours.
8. The application of the Co2P nanoparticle@Carbon@CNTs composite material according to claim 1 in the field of lithium-ion battery anode materials.