Preparation method of copper-doped bismuth selenide / carbon dot composite material and application of copper-doped bismuth selenide / carbon dot composite material to negative electrode of lithium ion battery
Through the preparation of copper-doped bismuth selenide/carbon dot composite materials, the transmission and structural stability problems of lithium-ion battery anode materials during lithium-embedding/delithation are solved, and efficient electrochemical lithium storage performance is achieved.
Patent Information
- Application Number
- CN202510491777.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-18
- Publication Date
- 2025-07-18
AI Technical Summary
The existing lithium-ion battery negative electrode material bismuth selenide, in the lithium-ion embedded/delithium delimitation process, has poor reaction reversibility and rate performance, and has large volume changes during alloying, resulting in reduced cycle stability.
The preparation method of copper-doped bismuth selenide/carbon dot composite material is adopted, and the carbon dots are closely attached to the copper-doped bismuth selenide nanosheets by solvothermal method to build a stable heterogeneous interface to enhance conductivity and structural stability.
The electrochemical lithium storage performance of lithium-ion battery anode material has been significantly improved, and the initial Coulomb efficiency and cycling performance have been improved.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of the preparation of nanocomposites, relates to composite electrode materials, and particularly relates to a preparation method of a copper-doped bismuth selenide / carbon dots (Cu x Bi 2-x Se3 / CDs) composite material and its application to the negative electrode of a lithium-ion battery. Background Art
[0002] Lithium-ion batteries (LIBs) have been widely used in the fields of portable electronic devices and electric vehicles due to their advantages such as high energy density and long cycle life. In recent years, the rapid development of large-scale applications such as electric vehicles and smart grids has put forward higher requirements for the energy density, cost, and safety of lithium-ion batteries. As one of the key components of LIBs, the inherent nature of the negative electrode material has a great impact on the battery performance. Currently, the commercial negative electrode material for LIBs is graphite, and its theoretical capacity is only 372 mAh g -1 , which greatly limits the improvement of the battery energy density. Therefore, it is particularly important to design and develop high-performance negative electrode materials for lithium-ion batteries.
[0003] Among many candidate negative electrode materials, bismuth selenide (Bi2Se3) not only has a high electronic conductivity (10.6 S·m -1 ), but also its unique conversion-alloying composite lithium storage mechanism enables it to exhibit a high theoretical capacity, and it has become one of the most promising candidate materials for the negative electrode of lithium-ion batteries. However, bulk Bi2Se3 has the following two problems during the lithium intercalation / deintercalation process: one is the slow electron / lithium ion transport, resulting in poor reaction reversibility and rate performance; the other is the large volume change during the alloying process, causing the collapse of the electrode structure and the reduction of the cycle stability, which greatly limits the practical application of such materials.
[0004] To solve the above problems, researchers have proposed two modification strategies of element doping and surface modification, that is, to optimize the electronic structure of the material through element doping, promote the bulk charge transfer, and reduce the Li + diffusion barrier; to enhance the conductivity and structural stability of the material through surface modification, and then improve the electrochemical performance of the electrode material. Carbon dots (CDs) are a type of zero-dimensional carbon nanomaterial with a size not exceeding 10 nm and easy to be prepared on a large scale. Modifying the surface of the active material with CDs can not only reduce the particle agglomeration during the synthesis process, but also construct a stable heterojunction interface to accelerate the charge transfer, and at the same time significantly enhance the stability of the electrode / electrolyte interface, thereby improving the initial Coulomb efficiency and cycle performance of the material. Therefore, it is expected to significantly improve the lithium storage performance of Bi2Se3 by modifying the surface of element-doped Bi2Se3 with CDs. Summary of the Invention
[0005] Aiming at the deficiencies existing in the above-mentioned prior art, the purpose of the present invention is to provide a preparation method of copper-doped bismuth selenide / carbon dots (Cu x Bi 2-x Se3 / CDs) composite material.
[0006] Technical Solution
[0007] A preparation method of copper-doped bismuth selenide / carbon dots (Cu x Bi 2-x Se3 / CDs) composite material includes the following steps: adding solution a to the carbon dot dispersion liquid, stirring for 4 - 8 h, preferably 6 h; adding solution b, stirring for 0.5 - 1.5 h, preferably 1 h; then adding solution c, stirring for 0.5 - 1.5 h, preferably 1 h; finally adding a reducing agent, stirring for 0.5 - 1.5 h, preferably 1 h; transferring the mixed system to a high-pressure reaction kettle, reacting at 140 - 200 °C for 10 - 20 h, preferably reacting at 195 °C for 15 h, centrifuging and separating, washing the precipitate with an organic solvent for 1 - 5 times, preferably 3 times, washing with deionized water for 1 - 3 times, and freeze-drying to obtain the copper-doped bismuth selenide / carbon dots composite material; wherein, the solution a is obtained by adding a copper salt to ethylene glycol and stirring to dissolve to obtain a solution a with a concentration of 0.01 - 0.05 mol / L, preferably 0.03 mol / L; the solution b is obtained by adding a bismuth salt to ethylene glycol and stirring to dissolve to obtain a solution b with a concentration of 0.06 - 0.10 mol / L, preferably 0.08 mol / L; the solution c is obtained by adding sodium selenite (Na2SeO3) to ethylene glycol and stirring to dissolve to obtain a solution c with a concentration of 0.10 - 0.16 mol / L, preferably 0.12 mol / L.
[0008] In a preferred disclosure example of the present invention, the concentration of the carbon dot dispersion liquid is 1 - 3 mg / mL, preferably 2 mg / mL.
[0009] Furthermore, the preparation method of the carbon dots is as follows: ultrasonically dispersing 0.15 g of 1,3,6-trinitropyrene in a 0.24 mol / L sodium hydroxide solution, transferring it to a 50 mL high-pressure reaction kettle, heating to 180 °C and reacting for 12 h, after cooling to room temperature, dialyzing the black solution for 3 d, and freeze-drying, and the obtained particles are the carbon dots.
[0010] Furthermore, the freeze-drying temperature is -60 - -40 °C, preferably -50 °C.
[0011] In a preferred disclosure example of the present invention, the volume ratio of solution a, solution b, solution c to the carbon dot dispersion liquid is 3:3:6:1 - 4, preferably 3:3:6:2.
[0012] In a preferred embodiment of the present invention, the molar ratio of sodium selenite to the reducing agent is 6 mmol:6 mmol to 6 mmol:8 mmol, preferably 6 mmol:7 mmol.
[0013] In a preferred embodiment of the present invention, the copper salt is copper nitrate trihydrate (Cu(NO3)2·3H2O), copper sulfate pentahydrate (CuSO4·5H2O), copper chloride dihydrate (CuCl2·2H2O) or basic copper sulfate (Cu2(OH)2SO4), preferably copper nitrate trihydrate (Cu(NO3)2·3H2O).
[0014] In a preferred embodiment of the present invention, the bismuth salt is bismuth nitrate pentahydrate (Bi(NO3)3·5H2O), bismuth trichloride (BiCl3), bismuth acetate (C6H9BiO6), bismuth sulfate (Bi2O 12 S3) or bismuth citrate (C6H5BiO7), preferably bismuth nitrate pentahydrate (Bi(NO3)3·5H2O).
[0015] In a preferred disclosed embodiment of the present invention, the reducing agent is L-ascorbic acid (C6H8O6), hydrazine hydrate (N2H4·H2O) or hydroxylamine (H3NO), preferably L-ascorbic acid (C6H8O6).
[0016] In a preferred embodiment of the present invention, the organic solvent is methanol (CH3OH), ethanol (CH3CH2OH) or acetone (CH3COCH3), preferably methanol (CH3OH).
[0017] According to the copper-doped bismuth selenide / carbon dot composite negative electrode material prepared by the method of the present invention, the carbon dots are tightly attached to the copper-doped bismuth selenide nanosheets, wherein the diameter of the nanosheets is 400-650 nm.
[0018] Another object of the present invention is to apply the prepared copper-doped bismuth selenide / carbon dot composite nanomaterial to the negative electrode of a lithium-ion battery.
[0019] The invention assembles the prepared copper-doped bismuth selenide / carbon dot composite material into a 2032-type button-type half-cell to study the lithium storage performance.
[0020] The preparation process of the working electrode is as follows: first, 80 wt.% of the active material (synthesized sample), 10 wt.% of the conductive carbon black and 10 wt.% of the sodium carboxymethyl cellulose binder are fully mixed with an appropriate amount of deionized water, then evenly coated on a copper foil, and vacuum dried at 80 °C for 8 h, and finally cut into discs with a diameter of 12 mm. The average loading of active material on each disc is 1.0-1.2 mg cm -2. The lithium metal foil was used as the counter electrode and reference electrode, the separator was a Celgard 2325 microporous membrane, and the electrolyte was a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) (volume ratio 1:1) with 1.0 M LiPF6, and 5 wt. % fluoroethylene carbonate (FEC) was added. The assembly of the 2032 coin-type half-cell was completed in a glove box filled with argon. Through a battery test system (model: NEWARE-BTS-4008), the cyclic performance test of the 2032 coin-type half-cell was completed in the voltage range of 0.01 - 3.0 V (vs. Li + / Li).
[0021] Beneficial effects
[0022] The present invention utilizes a one-step solvothermal method to prepare a copper-doped bismuth selenide / carbon dots composite anode material by adjusting factors such as the dosage of carbon dots and the reaction temperature. When applied to the anode material of a lithium-ion battery, it exhibits excellent electrochemical lithium storage performance. The operation process of the present invention is simple and easy to implement, with high reaction efficiency, and is easy to scale up production and industrialize. Brief description of the drawings
[0023] Figure 1 . X-ray diffraction (XRD) pattern of the copper-doped bismuth selenide / carbon dots composite nanomaterial prepared in Example 1.
[0024] Figure 2 . Transmission electron microscope (TEM) photograph of the copper-doped bismuth selenide / carbon dots composite nanomaterial prepared in Example 1.
[0025] Figure 3 . X-ray energy spectrum (EDS) element distribution map of the copper-doped bismuth selenide / carbon dots composite nanomaterial prepared in Example 1.
[0026] Figure 4 . Cyclic performance graph of the copper-doped bismuth selenide / carbon dots composite nanomaterial prepared in Example 1 used as the anode material of a lithium-ion battery at a current density of 100 mA·g -1 -1. Detailed description of the specific embodiments
[0027] The present invention will be described in detail below with reference to the embodiments to enable those skilled in the art to better understand the present invention. However, the present invention is not limited to the following embodiments.
[0028] Example 1
[0029] A preparation method of a copper-doped bismuth selenide / carbon dots (Cu x Bi 2-x Se3 / CDs) composite material, comprising:
[0030] Disperse 10 mg of carbon dots in 5 ml of ethylene glycol solution by ultrasonic treatment for 1 h to obtain a carbon dot dispersion;
[0031] Dissolve 0.39 g of bismuth nitrate pentahydrate in 7.5 mL of ethylene glycol solution. Add this solution to the above carbon dot dispersion. After stirring the mixture for 6 h, add a copper nitrate trihydrate solution (containing 0.07 g of copper nitrate trihydrate and 7.5 ml of ethylene glycol). After stirring for 1 h, add a sodium selenite solution (containing 0.21 g of sodium selenite and 15 ml of ethylene glycol). After stirring for 1 h, add 0.25 g of ascorbic acid. After stirring the mixture for 1 h, transfer it to a 50 ml autoclave, heat it to 195 °C, and react for 15 h;
[0032] After the solution is cooled to room temperature, centrifuge it, wash it 3 times with methanol and 2 times with deionized water, and freeze-dry it at -50 °C to obtain the final product of copper-doped bismuth selenide / carbon dot composite nanomaterial.
[0033] Figure 1 This is the XRD pattern of the prepared product. The positions of the characteristic peaks of the product are consistent with the standard card of hexagonal bismuth selenide, indicating the successful preparation of copper-doped bismuth selenide / carbon dot composite nanomaterial.
[0034] Figure 2 This is the TEM image of the prepared product. It can be seen that copper-doped bismuth selenide has a unique flaky nanostructure with a diameter of 400 - 650 nm.
[0035] Figure 3 This is the EDS elemental distribution map of the prepared product. It can be seen that the four elements C, Cu, Bi, and Se are evenly distributed in the copper-doped bismuth selenide / carbon dot composite material. Among them, the C element comes from the carbon dots, which confirms that the carbon dots are uniformly modified on the surface of the copper-doped bismuth selenide nanosheets, and copper elements are successfully incorporated into the bismuth selenide nanosheets.
[0036] Figure 4 This is the cycling performance graph of the prepared copper-doped bismuth selenide / carbon dot composite nanomaterial as the anode material for lithium-ion batteries, showing that the synthesized material has a high specific capacity and cycling performance. At a current density of 100 mA·g -1 After 50 cycles, the capacity is as high as 575 mA h·g -1 .
[0037] Example 2
[0038] A preparation method of a copper-doped bismuth selenide / carbon dot (Cu x Bi 2-x Se3 / CDs) composite material, including:
[0039] Disperse 5 mg of carbon dots in 2.5 ml of ethylene glycol solution by ultrasonic treatment for 1 h to obtain a carbon dot dispersion;
[0040] Dissolve 0.39 g of bismuth nitrate pentahydrate in 7.5 mL of ethylene glycol solution. Add this solution to the above carbon dot dispersion. After stirring the mixture for 6 h, add a copper nitrate trihydrate solution (containing 0.07 g of copper nitrate trihydrate and 7.5 ml of ethylene glycol), stir for 1 h, then add a sodium selenite solution (containing 0.21 g of sodium selenite and 15 ml of ethylene glycol), stir for 1 h, then add 0.25 g of ascorbic acid. After stirring the mixture for 1 h, transfer it to a 50 ml autoclave, heat to 195 °C, and react for 15 h;
[0041] After the solution is cooled to room temperature, centrifuge it, wash it 3 times with methanol and 2 times with deionized water, and freeze-dry it at -50 °C to obtain the final product of copper-doped bismuth selenide / carbon dot composite nanomaterial.
[0042] The prepared copper-doped bismuth selenide / carbon dot composite nanomaterial is used as the anode material of a lithium-ion battery. At a current density of 100 mA·g -1 After 50 cycles, the capacity is as high as 590 mA h·g -1 .
[0043] Example 3
[0044] A preparation method of a copper-doped bismuth selenide / carbon dot (Cu x Bi 2-x Se3 / CDs) composite material, including:
[0045] Disperse 15 mg of carbon dots in 7.5 ml of ethylene glycol solution by ultrasonic treatment for 1 h to obtain a carbon dot dispersion;
[0046] Dissolve 0.39 g of bismuth nitrate pentahydrate in 7.5 mL of ethylene glycol solution. Add this solution to the above carbon dot dispersion. After stirring the mixture for 6 h, add a copper nitrate trihydrate solution (containing 0.07 g of copper nitrate trihydrate and 7.5 ml of ethylene glycol), stir for 1 h, then add a sodium selenite solution (containing 0.21 g of sodium selenite and 15 ml of ethylene glycol), stir for 1 h, then add 0.25 g of ascorbic acid. After stirring the mixture for 1 h, transfer it to a 50 ml autoclave, heat to 195 °C, and react for 15 h;
[0047] After the solution is cooled to room temperature, centrifuge it, wash it 3 times with methanol and 2 times with deionized water, and freeze-dry it at -50 °C to obtain the final product of copper-doped bismuth selenide / carbon dot composite nanomaterial.
[0048] The prepared copper-doped bismuth selenide / carbon dot composite nanomaterial as the anode material for lithium-ion batteries, at a current density of 100 mA·g -1 after 50 cycles, the capacity is as high as 540 mA h·g -1 .
[0049] Example 4
[0050] A preparation method of a copper-doped bismuth selenide / carbon dot (Cu x Bi 2-x Se3 / CDs) composite material, comprising:
[0051] Ultrasonically disperse 10 mg of carbon dots in 5 ml of ethylene glycol solution for 1 h to obtain a carbon dot dispersion;
[0052] Dissolve 0.39 g of bismuth nitrate pentahydrate in 7.5 mL of ethylene glycol solution, add this solution to the above carbon dot dispersion, stir the mixture for 6 h, then add copper nitrate trihydrate solution (containing 0.05 g of copper nitrate trihydrate, 7.5 ml of ethylene glycol), stir for 1 h, then add sodium selenite solution (containing 0.21 g of sodium selenite, 15 ml of ethylene glycol), stir for 1 h, then add 0.25 g of ascorbic acid, stir the mixture for 1 h and transfer it to a 50 ml autoclave, heat to 195 °C, and react for 15 h;
[0053] After the solution is cooled to room temperature, centrifuge, wash 3 times with methanol, wash 2 times with deionized water, and freeze-dry at -50 °C to obtain the final product of copper-doped bismuth selenide / carbon dot composite nanomaterial.
[0054] The prepared copper-doped bismuth selenide / carbon dot composite nanomaterial as the anode material for lithium-ion batteries, at a current density of 100 mA·g -1 after 50 cycles, the capacity is as high as 570 mA h·g -1 .
[0055] Example 5
[0056] A preparation method of a copper-doped bismuth selenide / carbon dot (Cu x Bi 2-x Se3 / CDs) composite material, comprising:
[0057] Ultrasonically disperse 10 mg of carbon dots in 5 ml of ethylene glycol solution for 1 h to obtain a carbon dot dispersion;
[0058] Dissolve 0.39 g of bismuth nitrate pentahydrate in 7.5 mL of ethylene glycol solution, add this solution to the above carbon dot dispersion, stir the mixture for 6 h, then add copper nitrate trihydrate solution (containing 0.10 g of copper nitrate trihydrate, 7.5 ml of ethylene glycol), stir for 1 h, then add sodium selenite solution (containing 0.21 g of sodium selenite, 15 ml of ethylene glycol), stir for 1 h, then add 0.25 g of ascorbic acid, stir the mixture for 1 h and transfer it to a 50 ml autoclave, heat up to 195 °C and react for 10 h;
[0059] After the solution is cooled to room temperature, centrifuge it, wash it 3 times with methanol and 2 times with deionized water, and freeze-dry it at -50 °C to obtain the final product of copper-doped bismuth selenide / carbon dot composite nanomaterial.
[0060] The prepared copper-doped bismuth selenide / carbon dot composite nanomaterial is used as the anode material of a lithium-ion battery, at a current density of 100 mA·g -1 After 50 cycles, the capacity is as high as 500 mA h·g -1 .
[0061] Example 6
[0062] A preparation method of a copper-doped bismuth selenide / carbon dot (Cu x Bi 2-x Se3 / CDs) composite material, comprising:
[0063] Ultrasonically disperse 15 mg of carbon dots in 7.5 ml of ethylene glycol solution for 1 h to obtain a carbon dot dispersion;
[0064] Dissolve 0.39 g of bismuth nitrate pentahydrate in 7.5 mL of ethylene glycol solution, add this solution to the above carbon dot dispersion, stir the mixture for 6 h, then add copper nitrate trihydrate solution (containing 0.05 g of copper nitrate trihydrate, 7.5 ml of ethylene glycol), stir for 1 h, then add sodium selenite solution (containing 0.21 g of sodium selenite, 15 ml of ethylene glycol), stir for 1 h, then add 0.25 g of ascorbic acid, stir the mixture for 1 h and transfer it to a 50 ml autoclave, heat up to 195 °C and react for 15 h;
[0065] After the solution is cooled to room temperature, centrifuge it, wash it 3 times with methanol and 2 times with deionized water, and freeze-dry it at -50 °C to obtain the final product of copper-doped bismuth selenide / carbon dot composite nanomaterial.
[0066] The prepared copper-doped bismuth selenide / carbon dot composite nanomaterial is used as the anode material of a lithium-ion battery, at a current density of 100 mA·g -1Under such circumstances, after 50 cycles, the capacity is as high as 532 mA h·g -1 .
[0067] The above are only embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made using the specification of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.
Claims
1. A preparation method of a copper-doped bismuth selenide / carbon dot composite material, characterized in that, It includes the following steps: adding solution a to the carbon dot dispersion, stirring for 4 to 8 h, preferably 6 h; adding solution b, stirring for 0.5 to 1.5 h, preferably 1 h; then adding solution c, stirring for 0.5 to 1.5 h, preferably 1 h; finally adding a reducing agent, stirring for 0.5 to 1.5 h, preferably 1 h; transferring the mixed system to a high-pressure reactor and reacting at 140 to 200 °C for 10 to 20 h, preferably reacting at 195 °C for 15 h, centrifuging and separating, washing the precipitate with an organic solvent for 1 to 5 times, preferably 3 times, washing with deionized water for 1 to 3 times, and freeze-drying to obtain a copper-doped bismuth selenide / carbon dot composite material; wherein, the solution a is obtained by adding a copper salt to ethylene glycol and stirring to dissolve to obtain a solution a with a concentration of 0.01 to 0.05 mol / L, preferably 0.03 mol / L; the solution b is obtained by adding a bismuth salt to ethylene glycol and stirring to dissolve to obtain a solution b with a concentration of 0.06 to 0.10 mol / L, preferably 0.08 mol / L; the solution c is obtained by adding sodium selenite to ethylene glycol and stirring to dissolve to obtain a solution c with a concentration of 0.10 to 0.16 mol / L, preferably 0.12 mol / L.
2. The preparation method of the copper-doped bismuth selenide / carbon dot composite material according to claim 1, characterized in that: The concentration of the carbon dot dispersion is 1 to 3 mg / mL, preferably 2 mg / mL.
3. The preparation method of the copper-doped bismuth selenide / carbon dot composite material according to claim 1, wherein, The preparation method of the carbon dots is as follows: ultrasonically dispersing 0.15 g of 1,3,6-trinitropyrene in a 0.24 mol / L sodium hydroxide solution, transferring it to a 50 mL high-pressure reactor, heating to 180 °C and reacting for 12 h, after cooling to room temperature, dialyzing the black solution for 3 d, and freeze-drying. The obtained particles are the carbon dots; wherein, the freeze-drying temperature is -60 to -40 °C, preferably -50 °C.
4. The preparation method of the copper-doped bismuth selenide / carbon dot composite material according to claim 1, wherein: The volume ratio of solution a, solution b, solution c to the carbon dot dispersion is 3:3:6:1 to 4, preferably 3:3:6:
2.
5. The preparation method of the copper-doped bismuth selenide / carbon dot composite material according to claim 1, wherein: The molar ratio of sodium selenite to the reducing agent is 6 mmol:6 mmol to 6 mmol:8 mmol, preferably 6 mmol:7 mmol.
6. The preparation method of the copper-doped bismuth selenide / carbon dot composite material according to claim 1, wherein: The copper salt is copper(II) nitrate trihydrate Cu(NO3)2·3H2O, copper(II) sulfate pentahydrate CuSO4·5H2O, copper(II) chloride dihydrate CuCl2·2H2O or basic copper sulfate Cu2(OH)2SO4, preferably copper(II) nitrate trihydrate Cu(NO3)2·3H2O.
7. The preparation method of the copper-doped bismuth selenide / carbon dot composite material according to claim 1, characterized in that: The bismuth salt is bismuth nitrate pentahydrate Bi(NO3)3·5H2O, bismuth trichloride BiCl3, bismuth acetate C6H9BiO6, bismuth sulfate (Bi2O 12 S3) or bismuth citrate C6H5BiO7, preferably bismuth nitrate pentahydrate Bi(NO3)3·5H2O.
8. The preparation method of the copper-doped bismuth selenide / carbon dot composite material according to claim 1, characterized in that: The reducing agent is L-ascorbic acid C6H8O6, hydrazine hydrate N2H4·H2O or hydroxylamine H3NO, preferably L-ascorbic acid C6H8O6; the organic solvent is methanol CH3OH, ethanol CH3CH2OH or acetone CH3COCH3, preferably methanol CH3OH.
9. The copper-doped bismuth selenide / carbon dot composite material prepared by the method according to any one of claims 1-8, characterized in that: In the material, the carbon dots are tightly attached to the copper-doped bismuth selenide nanosheets, and the diameter of the nanosheets is 400 to 650 nm.
10. Use of the copper-doped bismuth selenide / carbon dot composite material according to claim 9, characterized in that: Apply it to the negative electrode of a lithium-ion battery.