Polymer electrolyte modified black phosphorus / carbon quantum dot composite material and preparation method and application thereof
Patent Information
- Application Number
- CN202310972364.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-03
- Publication Date
- 2026-08-21
- Estimated Expiration
- 2043-08-03
AI Technical Summary
但黑磷在充放电时体积变化较大(约300％)，会导致电导率降低，循环容量衰减
[0023](1)本发明将经过聚合物电解质改性的碳量子点，通过静电自组装与黑磷片层材料复合，之后真空烘干得到分散均匀的聚合物电解质改性黑磷/碳量子点复合材料，操作方法简便。
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Figure CN117133888B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrochemical technology, and in particular relates to a polymer electrolyte-modified black phosphorus / carbon quantum dot composite material, its preparation method and application. Background Technology
[0002] The overuse of traditional petrochemical resources has led to a severe energy and environmental crisis. In this dire situation, clean and green energy has developed rapidly in recent years. Solar, hydro, and wind power are the most promising energy sources to replace fossil fuels. However, due to the instability of their production processes, these energy sources cannot be used directly and must be stably stored and supplied using batteries. Currently, batteries are widely used as portable power sources in various devices, such as electronic devices, mobile communication devices, electric vehicles, and spacecraft.
[0003] Anode materials are crucial components for energy storage in batteries. Alloy anode materials typically possess high theoretical specific capacity, especially those with elements like Si, Ge, and P, which offer significant advantages over graphite in both mass and volumetric specific capacity. Furthermore, their relatively high lithium intercalation potential prevents the formation of lithium dendrites during intercalation, ensuring battery safety. However, alloy anode materials face substantial volume expansion during lithium intercalation, and the resulting stress and strain can lead to structural damage, limiting their further application in energy storage.
[0004] In recent years, phosphorus-based materials have attracted great interest due to their excellent physical properties and potential applications. Under environmental conditions, black phosphorus is the most stable allotrope of phosphorus. The structure of black phosphorus is similar to graphene, exhibiting a layered, wrinkled structure with layers connected by weak van der Waals forces. Each phosphorus atom is linked to three neighboring atoms by strong covalent bonds, forming a Z-shape in the x-direction and an armchair shape in the z-direction. This anisotropic crystalline structure endows black phosphorus with different physicochemical properties in different crystal orientations. In battery anode materials, each P atom of black phosphorus can react with three Li or Na atoms to form Li3P and Na3P, with a theoretical specific capacity as high as 2596 mAh / g, far exceeding that of graphite anodes (372 mAh / g), demonstrating excellent energy storage performance. However, black phosphorus experiences significant volume changes (approximately 300%) during charge and discharge, leading to decreased conductivity and reduced cycle capacity. Therefore, it is urgent to develop corresponding strategies for modifying two-dimensional black phosphorus materials so that the conductivity, stability and energy storage performance of black phosphorus composite materials can be synergistically optimized. Summary of the Invention
[0005] The purpose of this invention is to overcome the key problems of large volume expansion and cycle capacity decay in the aforementioned phosphorus-based electrode materials by providing a polymer electrolyte-modified black phosphorus / carbon quantum dot composite material, its preparation method, and its application. A polymer electrolyte-modified black phosphorus / carbon quantum dot composite material is obtained by peeling black phosphorus blocks into fewer layers of black phosphorus sheets using a reasonable peeling method, and then employing effective modification techniques to rationally design the electrode material.
[0006] The objective of this invention can be achieved through the following technical solutions:
[0007] A polymer electrolyte-modified black phosphorus / carbon quantum dot composite material includes black phosphorus sheet material and carbon quantum dots; the carbon quantum dots are modified with polymer electrolyte and uniformly dispersed on the surface of black phosphorus sheet material.
[0008] Furthermore, the polymer electrolyte includes one of polyethyleneimine (PEI), polydiallyldimethylammonium chloride (PDDA), or polyethylene polyamine (PEPA).
[0009] This invention also provides a method for preparing a polymer electrolyte-modified black phosphorus / carbon quantum dot composite material, comprising the following steps:
[0010] (1) Black phosphorus crystals obtained by high-temperature calcination are peeled to obtain black phosphorus sheet material;
[0011] (2) The carbon source solution was subjected to a high-temperature solvothermal reaction, dried and then calcined at high temperature to obtain carbon quantum dot powder; it was dissolved in an alcohol solvent to obtain a carbon quantum dot solution, a polymer electrolyte was added and stirred, and then ultrasonically homogenized.
[0012] (3) Add the black phosphorus sheet material to the polymer electrolyte-modified carbon quantum dot solution, stir and mix, sonicate and dry to obtain the polymer electrolyte-modified black phosphorus / carbon quantum dot composite material.
[0013] Further, the black phosphorus crystals mentioned in step (1) are obtained by mixing red phosphorus particles with tin and iodine and then calcining at high temperature; the high temperature calcination process is from 15-25℃ to 580-600℃ to 480-500℃ to 110-130℃, and the rate is 0.6-1.6℃ / min.
[0014] Furthermore, the stripping described in step (1) is electrochemical stripping, followed by ultrasonication for 8-10 hours, and the black phosphorus sheet material is collected by centrifugation at 8000-10000 rpm.
[0015] Furthermore, the carbon source mentioned in step (2) includes citric acid, L-cysteine, and one type of biomass carbon material.
[0016] Furthermore, in step (2), the temperature of the solvothermal reaction is 180-220℃ and the reaction time is 4-6h; the high-temperature calcination temperature is 550-750℃ and the calcination time is 1-3h.
[0017] Furthermore, in step (2), the volume ratio of carbon quantum dot solution to polymer electrolyte is (10-100):1; the stirring time is 1-2 h, and the ultrasonic time is 1-2 h.
[0018] Furthermore, in step (3), the stirring time is 4-12 hours and the ultrasonic time is 1-2 hours.
[0019] As a preferred technical solution of the present invention, the polymer electrolyte modified black phosphorus / carbon quantum dot composite material presents as a black powder with a metallic luster, and the nano-sized carbon quantum dots are uniformly distributed on the surface of the micron-sized black phosphorus sheets.
[0020] This invention also provides an application of polymer electrolyte-modified black phosphorus / carbon quantum dot composite material in electrochemical energy storage, such as anode materials for lithium, sodium, and potassium-ion batteries.
[0021] This invention uses exfoliated black phosphorus sheets as the substrate material. The charge distribution on the surface of carbon quantum dots is altered by adding a polymer electrolyte. The black phosphorus sheet solution is then added to the polymer electrolyte-modified carbon quantum dot solution and stirred. Finally, vacuum drying yields a polymer electrolyte-modified black phosphorus / carbon quantum dot composite material. Compared to traditional materials, low-dimensional nanomaterials, represented by quantum dots, can provide faster ion transport and conductivity for secondary batteries. Combining quantum dots with black phosphorus not only prevents the aggregation of quantum dots and buffers the volume expansion of the material during charge and discharge, but also leverages their synergistic effect. This invention selects carbon quantum dots (CQDs) as the conductive composite material to modify the surface of black phosphorus. By controlling the different contents and bonding modes of black phosphorus and carbon quantum dots, the optimal ratio of the composite material and its performance optimization mechanism during energy storage are explored.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] (1) In this invention, carbon quantum dots modified by polymer electrolyte are combined with black phosphorus sheet material through electrostatic self-assembly, and then vacuum dried to obtain a uniformly dispersed polymer electrolyte modified black phosphorus / carbon quantum dot composite material. The operation method is simple.
[0024] (2) This invention uses commonly used carbon sources to prepare carbon quantum dots and commonly used polymer electrolytes for modification. The raw materials are designable and have wide applications.
[0025] (3) This invention modifies black phosphorus with modified carbon quantum dots, which significantly improves its conductivity. Simultaneously, the low-dimensional material coating effectively alleviates the volume expansion of the black phosphorus material. The cross-linking of carbon quantum dots forms a network structure, enhancing the cycling stability of the composite material and reducing capacity decay. Modifying the carbon quantum dots with a positively charged polymer electrolyte (such as PDDA) and adding it to the black phosphorus solution strengthens their electrostatic bonding and increases their conductivity. The modified carbon quantum dots are uniformly distributed on the black phosphorus sheets. The addition of the polymer electrolyte improves the dispersion of the carbon quantum dots and enhances the stability of the composite material, resulting in high reversible capacity and excellent cycling stability.
[0026] (4) This invention incorporates polymer electrolyte-modified carbon quantum dots, resulting in a well-bonded polymer electrolyte-modified black phosphorus / carbon quantum dot composite material. The nanoscale carbon quantum dots are uniformly loaded on the surface of the black phosphorus sheets, improving the cycle stability of the composite material and showing broad application prospects in the field of lithium-ion batteries. Simultaneously, it provides excellent experimental data and theoretical support for the research and application of phosphorus-based composite materials in the field of electrochemical energy storage. Attached Figure Description
[0027] Figure 1 TEM images of the black phosphorus / carbon quantum dot composite materials prepared in Example 1 and Comparative Example 2.
[0028] Figure 2 The images show the XRD patterns of polymer electrolyte-modified black phosphorus / carbon quantum dot composites with different mass ratios in Examples 1-5.
[0029] Figure 3 The graphs show the cycle performance of black phosphorus / carbon quantum dot composite materials as positive electrodes for lithium-ion batteries in Examples 1-4, Comparative Examples 1 and 2. Detailed Implementation
[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.
[0031] Example 1
[0032] A method for preparing polymer electrolyte-modified black phosphorus / carbon quantum dot composite materials:
[0033] Step 1: Preparation of black phosphorus sheet material:
[0034] (1) 0.8g of red phosphorus particles were mixed with tin and iodine and vacuum sealed in a tube. The mixture was then calcined at a high temperature of 20℃ to 590℃ to 485℃ to 120℃ at a rate of 1℃ / min to obtain blocky black phosphorus crystals.
[0035] (2) Black phosphorus crystals were electrochemically stripped in 100 mL of N,N-dimethylformamide solution containing 16.1 g tetrabutylammonium bromide. The program was IT program, the voltage was -5 V, and the time was 3600 min.
[0036] (3) The above black phosphorus solution was deoxygenated and sonicated for 8 hours, dispersed in methanol, centrifuged at 1000 rpm for 10 minutes to take the upper layer solution to remove the large pieces that were not completely peeled off in the lower layer; then centrifuged at 9000 rpm three times, deoxygenated for 10 minutes and dispersed in ethanol solution, and finally dried in a vacuum oven at 60℃ for 12 hours.
[0037] Step 2: Preparation of carbon quantum dot materials
[0038] (1) 8.4 g of citric acid was stirred evenly in 80 mL of deionized water containing 2.68 mL of ethylenediamine and subjected to a solvothermal reaction in an oven at 200 °C for 5 h. Carbon quantum dot powder was obtained by dialysis and freeze drying.
[0039] (2) The powder was calcined at 600°C for 2 hours.
[0040] Step 3: Preparation of polymer electrolyte-modified black phosphorus / carbon quantum dot composite materials:
[0041] (1) Mix 100 mg of carbon quantum dots in 10 mL of ethanol and stir until homogeneous. Then add 100 μL of PDDA to the carbon quantum dot solution (at this time, the volume ratio of carbon quantum dot ethanol solution to polymer electrolyte is 100:1). Stir magnetically for 1 h and sonicate for 1 h to disperse it evenly.
[0042] (2) Disperse the 20mg black phosphorus sheet material prepared in the first step in 10mL ethanol and stir for 1h. Sonicate for 1h to make it uniformly dispersed. Then, add it dropwise to carbon quantum dot solution under anaerobic conditions, stir magnetically for 8h, sonicate for 2h, and vacuum dry to obtain the final polymer electrolyte modified black phosphorus / carbon quantum dot composite material.
[0043] The TEM image of the polymer electrolyte-modified black phosphorus / carbon quantum dot composite material prepared in Example 1 is shown below. Figure 1 As shown in Figure a, carbon quantum dots can be uniformly loaded onto the surface of the black phosphorus sheet and are firmly bonded.
[0044] Example 2
[0045] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the amount of black phosphorus added in the third step is 100mg.
[0046] Example 3
[0047] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the amount of black phosphorus added in the third step is 50mg.
[0048] Example 4
[0049] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the amount of black phosphorus added in the third step is 10mg.
[0050] Example 5
[0051] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the amount of black phosphorus added in the third step is 200mg.
[0052] Figure 2 The images show the XRD patterns of the polymer electrolyte-modified black phosphorus / carbon quantum dot composites with different mass ratios obtained in Examples 1-5. The obvious carbon peak and characteristic peak of black phosphorus can be seen, indicating the successful composite of black phosphorus / carbon quantum dot materials.
[0053] The present invention also provides the following comparative examples to demonstrate the beneficial technical effects of the present invention.
[0054] Comparative Example 1
[0055] Comparative Example 1 provides a black phosphorus material without added carbon quantum dots, and the specific operation is as follows:
[0056] (1) 0.8g of red phosphorus particles were mixed with tin and iodine and vacuum sealed in a tube. The mixture was then calcined at a high temperature of 20℃ to 590℃ to 485℃ to 120℃ at a rate of 1℃ / min to obtain blocky black phosphorus crystals.
[0057] (2) Black phosphorus crystals were electrochemically stripped in 100 mL of N,N-dimethylformamide solution containing 16.1 g tetrabutylammonium bromide. The program was IT program, the voltage was -5 V, and the time was 3600 min.
[0058] (3) The above black phosphorus solution was deoxygenated and sonicated for 8 hours, dispersed in methanol, centrifuged at 1000 rpm for 10 minutes to take the upper layer solution to remove the large pieces that were not completely peeled off in the lower layer; then centrifuged at 9000 rpm three times, deoxygenated for 10 minutes and dispersed in ethanol solution, and finally dried in a vacuum oven at 60℃ for 12 hours to obtain pure black phosphorus material.
[0059] Comparative Example 2
[0060] Comparative Example 2 provides a black phosphorus / carbon quantum dot composite material without polymer electrolyte modification, and the specific operation is as follows:
[0061] Step 1: Preparation of black phosphorus sheet material:
[0062] (1) 0.8g of red phosphorus particles were mixed with tin and iodine and vacuum sealed in a tube. The mixture was then calcined at a high temperature of 20℃ to 590℃ to 485℃ to 120℃ at a rate of 1℃ / min to obtain blocky black phosphorus crystals.
[0063] (2) Black phosphorus crystals were electrochemically stripped in 100 mL of N,N-dimethylformamide solution containing 16.1 g tetrabutylammonium bromide. The program was IT program, the voltage was -5 V, and the time was 3600 min.
[0064] (3) The above black phosphorus solution was deoxygenated and sonicated for 8 hours, dispersed in methanol, centrifuged at 1000 rpm for 10 minutes to take the upper layer solution to remove the large pieces that were not completely peeled off in the lower layer, centrifuged at 9000 rpm three times, deoxygenated for 10 minutes and dispersed in ethanol solution, and finally dried in a vacuum oven at 60℃ for 12 hours.
[0065] Step 2: Preparation of carbon quantum dot materials
[0066] (1) 8.4 g of citric acid was stirred evenly in 80 mL of deionized water containing 2.68 mL of ethylenediamine and subjected to a solvothermal reaction in an oven at 200 °C for 5 h. Carbon quantum dot powder was obtained by dialysis and freeze drying.
[0067] (2) The powder was calcined at 600°C for 2 hours.
[0068] Step 3: Preparation of polymer electrolyte-modified black phosphorus / carbon quantum dot composite materials:
[0069] (1) Mix 100 mg of carbon quantum dots in 10 mL of ethanol and stir until homogeneous to obtain a carbon quantum dot solution.
[0070] (2) The 20 mg black phosphorus sheet material prepared in the first step was dispersed in 10 mL of ethanol and stirred for 1 h. It was then sonicated for 1 h to make it uniformly dispersed. Subsequently, it was added dropwise to carbon quantum dot solution under anaerobic conditions, magnetically stirred for 8 h, sonicated for 2 h, and vacuum dried to obtain the final polymer electrolyte modified black phosphorus / carbon quantum dot composite material.
[0071] The TEM image of the black phosphorus / carbon quantum dot composite material prepared in Comparative Example 2 is shown below. Figure 1 As shown in b, it can be seen that the bond between carbon quantum dots and black phosphorus is not very strong; there are also a large number of scattered carbon quantum dots next to the black phosphorus sheets. Figure 1 There is a significant difference compared to a. Therefore, Figure 1 The TEM comparison images show that polymer dielectric modification plays an important role in the morphology of the final black phosphorus / carbon quantum dot composite material.
[0072] Meanwhile, this invention uses the obtained black phosphorus / carbon quantum dot composite material as the positive electrode of the lithium-ion battery half-cell to assemble the half-cell (which is used as the negative electrode material in the full cell, and only as the positive electrode material of the half-cell in the electrochemical performance test). The composite material, acetylene black and polyvinylidene fluoride are mixed in a weight ratio of 7:2:1 and then uniformly coated on pure copper foil (99.6%) to prepare the positive electrode, and pure lithium sheet is used as the negative electrode. Figure 3 The figures show the cycle performance of polymer electrolyte-modified black phosphorus / carbon quantum dot composites with different mass ratios obtained in Examples 1-4, and Comparative Examples 1 and 2 as positive electrodes for lithium-ion battery half-cells. It can be seen that the composite material with a polymer electrolyte-modified black phosphorus / carbon quantum dot mass ratio of 1:5 exhibits the best charge-discharge performance and cycle stability, maintaining a specific capacity of 376 mAh g⁻¹ after 88 charge-discharge cycles. -1 The performance is 2.52 times that of pure black phosphorus under the same cycle conditions, and 1.69 times that of the black phosphorus / carbon quantum dot composite material without PDDA modification. This indicates that the electrochemical performance of the black phosphorus / carbon quantum dot composite material modified with polymer electrolyte is significantly improved compared to black phosphorus alone and the black phosphorus / carbon quantum dot composite material without PDDA modification.
[0073] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A polymer electrolyte-modified black phosphorus / carbon quantum dot composite material, characterized in that, The material comprises black phosphorus sheet material and carbon quantum dots; the carbon quantum dots are modified with a polymer electrolyte and uniformly dispersed on the surface of the black phosphorus sheet material; the polymer electrolyte comprises one of polyethyleneimine, polydiallyldimethylammonium chloride, or polyethylenepolyamine. The polymer electrolyte-modified black phosphorus / carbon quantum dot composite material is obtained by the following preparation method, which includes the following steps: (1) Black phosphorus crystals obtained by high-temperature calcination are peeled to obtain black phosphorus sheet material; (2) The carbon source solution is subjected to a high-temperature solvothermal reaction, dried and then calcined at high temperature to obtain carbon quantum dot powder; it is dissolved in an alcohol solvent to obtain a carbon quantum dot solution, a polymer electrolyte is added and stirred, and then ultrasonically homogenized. (3) Add the black phosphorus sheet material to the polymer electrolyte modified carbon quantum dot solution, stir and mix, sonicate and dry to obtain polymer electrolyte modified black phosphorus / carbon quantum dot composite material.
2. The polymer electrolyte-modified black phosphorus / carbon quantum dot composite material according to claim 1, characterized in that, The black phosphorus crystals mentioned in step (1) are obtained by mixing red phosphorus particles with tin and iodine and then calcining at high temperature; the high temperature calcination process is from 15-25℃ to 580-600℃ to 480-500℃ to 110-130℃, and the rate is 0.6-1.6℃ / min.
3. The polymer electrolyte-modified black phosphorus / carbon quantum dot composite material according to claim 1, characterized in that, The stripping described in step (1) is electrochemical stripping. After stripping, the material is ultrasonicated for 8-10 hours and then centrifuged at 8000-10000 rpm to collect the black phosphorus sheet material.
4. The polymer electrolyte-modified black phosphorus / carbon quantum dot composite material according to claim 1, characterized in that, The carbon source mentioned in step (2) includes one of citric acid, L-cysteine, and biomass carbon materials.
5. The polymer electrolyte-modified black phosphorus / carbon quantum dot composite material according to claim 1, characterized in that, In step (2), the temperature of the solvothermal reaction is 180-220℃ and the reaction time is 4-6h; the high-temperature calcination temperature is 550-750℃ and the calcination time is 1-3h.
6. The polymer electrolyte-modified black phosphorus / carbon quantum dot composite material according to claim 1, characterized in that, In step (2), the volume ratio of carbon quantum dot solution to polymer electrolyte is (10~100):1; the stirring time is 1-2h, and the ultrasonic time is 1-2h.
7. The polymer electrolyte-modified black phosphorus / carbon quantum dot composite material according to claim 1, characterized in that, In step (3), the stirring time is 4-12 hours and the ultrasonic time is 1-2 hours.
8. The application of the polymer electrolyte modified black phosphorus / carbon quantum dot composite material as described in claim 1 as a negative electrode material for lithium, sodium, and potassium ion batteries in electrochemical energy storage.