Conjugated conductive polymer and carbon dual-coated micron silicon-carbon negative electrode material and preparation method thereof
By forming a double coating layer of conjugated conductive polymer and carbon on the surface of micron silicon, the conductivity and mechanical strength problems of micron silicon carbon negative electrode materials are solved, the stability and life of the material are improved, the production cost is reduced, and it is suitable for high-energy lithium-ion batteries.
Patent Information
- Application Number
- CN202510838711.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-23
- Publication Date
- 2025-09-16
AI Technical Summary
Micron silicon-carbon negative electrode materials in lithium-ion batteries have poor conductivity and limited mechanical strength of the single-layer carbon coating, making it difficult to suppress volume expansion and failure, resulting in a short cycle life and making it difficult to meet the commercial application needs of high-energy lithium-ion batteries.
A preparation method for micron silicon-carbon negative electrode material with double coating of conjugated conductive polymer and carbon is adopted. By forming a double coating layer of conjugated conductive polymer and carbon on the surface of micron silicon, the conductivity and mechanical strength of the material are improved and volume expansion is suppressed.
The stability and life of the micron silicon negative electrode are improved, the production cost is reduced, and it is suitable for large-scale industrial production to meet the needs of high-energy lithium-ion batteries.
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Figure CN120657101A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of new energy technology and relates to a method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material. Background Art
[0002] In the wave of global energy transformation and energy storage technology iteration, lithium-ion batteries have become the core energy storage technology for new energy vehicles, portable electronic devices and large-scale energy storage systems due to their advantages such as high energy density, long cycle life and no memory effect. The development of new high-capacity electrode materials is the key path to breaking the bottleneck of lithium-ion battery energy density. Silicon-based negative electrode materials have an ultra-high theoretical specific capacity (4200 mAh g-1). 1 ), is recognized as the most promising next-generation negative electrode material.
[0003] However, during the charge and discharge process of lithium-ion batteries, silicon anodes experience a volume expansion effect of up to 300-400%, leading to rapid pulverization and failure. Simultaneously, the solid electrolyte interface (SEI) repeatedly breaks and regenerates amidst the volume fluctuations of silicon particles, continuously and irreversibly consuming electrolyte and lithium ions, severely impacting the battery's cycle life. Current approaches to improving silicon anode stability include nanostructure design and carbon coating. Nanosilicon effectively mitigates volume expansion stress by reducing particle size, but its large surface area exacerbates electrolyte side reactions. Furthermore, the complex preparation process for nanosilicon leads to high production costs, making it difficult to meet the demands of large-scale applications. In contrast, micronized silicon, with its widespread availability and low cost, has become a promising alternative. However, compared to nanosilicon, micronized silicon faces a more severe volume expansion problem, as well as significant challenges in conductivity and reactivity. While traditional amorphous carbon coating can mitigate silicon volume expansion to some extent, its limited mechanical strength makes it ineffective in suppressing expansion stress and failure during long-term cycling, making it difficult to meet the performance requirements for commercial applications. The development of micron-silicon anodes with high specific capacity and long life has become an urgent need for the development of next-generation high-energy lithium-ion batteries. Summary of the Invention
[0004] To address the challenges of the prior art, the present invention aims to provide a method for preparing a micronized silicon-carbon anode material dually coated with a conjugated conductive polymer and carbon. This method aims to form a dual coating of conjugated conductive polymer and carbon on the surface of micronized silicon, addressing the poor conductivity of micronized silicon, the limited mechanical strength of a single carbon coating, and the difficulty in suppressing expansion and failure of micronized silicon. This method improves the stability and lifespan of the micronized silicon anode. This method addresses the urgent need for high-capacity, long-life, and low-cost silicon anodes in next-generation high-energy lithium-ion batteries, and has broad potential for application.
[0005] In order to achieve the above object, the technical solution adopted by the present invention is:
[0006] A method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material. The preparation method comprises the following steps: first, uniformly dispersing micron silicon powder in an alcohol solution containing a carbon source to obtain a precursor solution. Secondly, heating the precursor solution to remove the alcohol solvent, and then calcining it in an inert atmosphere under high temperature conditions to obtain carbon-coated micron silicon. Thirdly, uniformly mixing the obtained carbon-coated micron silicon and polymer in an organic solvent to form a slurry. Finally, the formed slurry is uniformly coated on a current collector, dried, and then heat-treated in an inert atmosphere to convert the polymer monomer into a conjugated conductive polymer, thereby obtaining a double-layer coated micron silicon-carbon negative electrode material coated with a conjugated conductive polymer and a carbon layer. Specifically, the following steps are included:
[0007] The first step is to evenly disperse micron silicon powder in an alcohol solution containing a carbon source to obtain a precursor solution. Specifically:
[0008] The micron silicon powder is a commercial product with a particle size of 1-10 μm.
[0009] The carbon source is one or more of polyacetylene, polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene)-polylactic acid, polyaniline and polyacrylonitrile.
[0010] In the precursor solution, the mass ratio of micron silicon to carbon source is 1:0.5-1:5.
[0011] The concentration of micronized silicon powder in the slurry is 1–5 g / ml.
[0012] In the alcohol solution containing a carbon source, the alcohol solvent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, and ethylene glycol.
[0013] In the second step, the precursor solution obtained in the first step is heated to remove the alcohol solvent, and then calcined in an inert atmosphere at high temperature to obtain carbon-coated micron silicon.
[0014] The heating temperature is 80-120°C.
[0015] The high temperature calcination temperature is 700-800°C, and the calcination time is 4-6 hours.
[0016] The inert gas is one or more of nitrogen and argon.
[0017] In the third step, the carbon-coated micron silicon obtained in the second step and the polymer are uniformly mixed in an organic solvent to form a slurry.
[0018] The polymer is one or more of polyacetylene, polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene)-polylactic acid, polyaniline and polyacrylonitrile. Specifically:
[0019] The mass ratio of the carbon-coated micron silicon to the polymer is 1:0.1-1:1.
[0020] In the slurry, the concentration of carbon-coated micro-silicon is 150-200 mg / ml.
[0021] The organic solvent is one or more of N,N-dimethylformamide, acetone, methanol and dimethyl sulfoxide.
[0022] In the fourth step, the slurry formed in the third step is evenly coated on the current collector, dried, and then heat-treated in an inert atmosphere to convert the conductive polymer monomer into a conjugated conductive polymer, thereby obtaining a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material.
[0023] Each 1 ml of slurry is applied on 25 ~ 100 cm 2 on the current collector.
[0024] The drying temperature is 80-120°C.
[0025] The heat treatment temperature is 260-320°C, and the heat treatment time is 1-2 h.
[0026] The inert gas is one or more of nitrogen and argon.
[0027] The current collector is made of one of copper, nickel, stainless steel and carbon.
[0028] The micron silicon, carbon source, solvent, polymer, etc. in the present invention are all conventional materials in the art and can be homemade or commercially available, and the present invention does not impose any particular limitation thereto.
[0029] A conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material is prepared by the above-mentioned preparation method and can be used in the preparation of high-energy lithium-ion batteries.
[0030] Compared with the prior art, the present invention solves the problem of rapid failure of micron-sized silicon-carbon negative electrode materials due to volume expansion, and has the following beneficial effects:
[0031] (1) Use low-cost micron silicon to replace large-surface-area, high-cost nano silicon to reduce the cost of silicon-carbon negative electrodes.
[0032] (2) By using a conjugated conductive polymer layer and a carbon layer to double-coat micron silicon, the problems of poor conductivity of micron silicon, limited mechanical strength of single-layer carbon coating, and difficulty in suppressing the expansion and failure of micron silicon can be solved through its promotion of electronic conduction and its own high adhesion.
[0033] (3) The conjugated conductive polymer layer can replace conventional binders and conductive agents while protecting the silicon negative electrode, further reducing the cost of the silicon negative electrode and improving the battery energy density.
[0034] (4) The preparation method of the conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material has a simple process, low cost, and can be applied to large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 This is a transmission electron microscope photograph of the conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material prepared in Example 1 of the present invention;
[0036] Figure 2 This is the first cycle capacity-voltage curve of the conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material prepared in Example 1 of the present invention;
[0037] Figure 3 This is the coulombic efficiency and cycle stability curve of the conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material prepared in Example 1 of the present invention. DETAILED DESCRIPTION
[0038] In response to the numerous shortcomings of the prior art, the inventors of this case, after extensive research and extensive practice, have proposed the technical solution of the present invention. This technical solution, its implementation process, and principles are further explained below. However, it should be understood that, within the scope of the present invention, the various technical features of the present invention and those specifically described below (in the Examples) may be combined to form new or preferred technical solutions.
[0039] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.
[0040] Example 1
[0041] 1) Disperse micronized silicon powder evenly in an ethanol solution containing polyacrylonitrile to obtain a precursor solution. The mass ratio of micronized silicon to polyacrylonitrile is 1:3, and the concentration of micronized silicon powder in the precursor solution is 3 g ml-1. 1 .
[0042] 2) The precursor solution obtained in step 1) was heated at 80° C. for 12 hours to remove the alcohol solvent, and then calcined at 800° C. in argon for 4 hours to obtain carbon-coated micron silicon.
[0043] 3) The carbon-coated micron silicon and polyacrylonitrile obtained in step 2) were uniformly mixed in N,N-dimethylformamide to form a slurry. The mass ratio of carbon-coated micron silicon to polyacrylonitrile was 1:0.3, and the concentration of carbon-coated micron silicon in the slurry was 175 mg ml- 1 .
[0044] 4) The slurry formed in step 3) was evenly coated on the copper current collector (1 ml of slurry was coated on 50 cm 2 The conductive polymer was converted into a conjugated conductive polymer in an inert atmosphere and a micron silicon-carbon negative electrode material was obtained by coating the conductive polymer with carbon.
[0045] Figure 1 This is a transmission electron microscope photograph of the conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material prepared in Example 1 of the present invention, and the coating layer formed on the surface of the micron silicon-carbon negative electrode material can be seen.
[0046] Figure 2 This is the first cycle capacity-voltage curve of the conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material prepared in Example 1 of the present invention. A half-cell was assembled with lithium metal as the counter electrode for testing. 1 At this current density, the battery's first cycle discharge capacity is 2560.6 mAh g- 1 The first cycle charge capacity is 1980.3mAh g- 1 , the first-cycle Coulomb efficiency is 77.3%.
[0047] Figure 3 The coulombic efficiency and cycle stability curves of the conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material prepared in Example 1 of the present invention are shown. A half-cell was assembled with lithium metal as the counter electrode for testing. 1 At this current density, after 100 cycles, the battery has a capacity retention rate of 66.9% and a Coulombic efficiency of 99.2%.
[0048] Example 2
[0049] 1) Disperse micronized silicon powder evenly in a methanol solution containing polyaniline to obtain a precursor solution. The mass ratio of micronized silicon to polyaniline is 1:5, and the concentration of micronized silicon powder in the precursor solution is 1 g ml-1. 1 .
[0050] 2) The precursor solution obtained in step 1) was heated at 120° C. to remove the alcohol solvent, and then calcined at 750° C. in argon for 5 h to obtain carbon-coated micron silicon.
[0051] 3) The carbon-coated micronized silicon and polyaniline obtained in step 2) were uniformly mixed in acetone to form a slurry. The mass ratio of carbon-coated micronized silicon to polyaniline was 1:0.1, and the concentration of carbon-coated micronized silicon in the slurry was 150 mg ml-1. 1 .
[0052] 4) The slurry formed in step 3) was evenly coated on the nickel current collector (1 ml of slurry was coated on 25 cm 2 The conductive polymer was coated on a copper current collector), dried at 80°C, and then heat-treated at 260°C in an inert atmosphere for 2 hours to convert the conductive polymer monomer into a conjugated conductive polymer, thereby obtaining a double-layer coated micron silicon-carbon negative electrode material coated with a conjugated conductive polymer and a carbon layer.
[0053] In this embodiment 2:
[0054] The first cycle capacity-voltage curve of the prepared conjugated conductive polymer and carbon double coated micron silicon carbon negative electrode material was tested by assembling a half cell with lithium metal as the counter electrode. 1 At this current density, the battery's first cycle discharge capacity is 2308.1mAh g- 1 The first cycle charge capacity is 1756.2mAh g- 1 , the first-cycle Coulomb efficiency is 76.1%.
[0055] The coulombic efficiency and cycling stability curves of the micronized silicon-carbon negative electrode material with double coating of conjugated conductive polymer and carbon were prepared. The half-cell was assembled with lithium metal as the counter electrode and tested. 1 At this current density, after 100 cycles, the battery has a capacity retention rate of 58.8% and a Coulombic efficiency of 98.5%.
[0056] Example 3
[0057] 1) Disperse micronized silicon powder evenly in a n-butanol solution containing polypyrrole to obtain a precursor solution. The mass ratio of micronized silicon to polypyrrole is 1:1, and the concentration of micronized silicon powder in the precursor solution is 5 g ml-1. 1 .
[0058] 2) The precursor solution obtained in step 1) was heated at 100° C. to remove the alcohol solvent, and then calcined at 700° C. in nitrogen for 6 h to obtain carbon-coated micron silicon.
[0059] 3) The carbon-coated micro-silicon and polypyrrole obtained in step 2) are uniformly mixed in dimethyl sulfoxide to form a slurry. The mass ratio of carbon-coated micro-silicon to polypyrrole is 1:1, and the concentration of carbon-coated micro-silicon in the slurry is 200 mg / ml. 1 .
[0060] 4) The slurry formed in step 3) was evenly coated on the copper current collector (1 ml of slurry was coated on 100 cm 2 The conductive polymer was coated on a copper current collector), dried at 100°C, and then heat-treated at 300°C in an inert atmosphere for 1.5 hours to convert the conductive polymer monomer into a conjugated conductive polymer, thereby obtaining a double-layer coated micron silicon-carbon negative electrode material coated with a conjugated conductive polymer and a carbon layer.
[0061] In this embodiment 3:
[0062] The first cycle capacity-voltage curve of the prepared conjugated conductive polymer and carbon double coated micron silicon carbon negative electrode material was tested by assembling a half cell with lithium metal as the counter electrode. 1 At this current density, the battery's first cycle discharge capacity is 2513.7 mAh g- 1 The first cycle charge capacity is 1327.2 mAh g- 1 , the first-cycle Coulomb efficiency is 52.8%.
[0063] The coulombic efficiency and cycling stability curves of the micronized silicon-carbon negative electrode material with double coating of conjugated conductive polymer and carbon were prepared. The half-cell was assembled with lithium metal as the counter electrode and tested. 1 At this current density, after 100 cycles, the battery has a capacity retention rate of 49.3% and a Coulombic efficiency of 98.1%.
[0064] Example 4
[0065] 1) Disperse micronized silicon powder evenly in an ethanol solution containing polythiophene to obtain a precursor solution. The mass ratio of micronized silicon to polythiophene is 1:0.5, and the concentration of micronized silicon powder in the precursor solution is 2 g ml-1. 1 .
[0066] 2) The precursor solution obtained in step 1) was heated at 80° C. to remove the alcohol solvent, and then calcined at 800° C. in argon for 2.5 h to obtain carbon-coated micron silicon.
[0067] 3) The carbon-coated micron silicon and polythiophene obtained in step 2) were uniformly mixed in methanol to form a slurry. The mass ratio of carbon-coated micron silicon to polythiophene was 1:0.5, and the concentration of carbon-coated micron silicon in the slurry was 175 mg ml- 1 .
[0068] 4) The slurry formed in step 3) was evenly coated on the stainless steel current collector (1 ml of slurry was coated on 75 cm 2The conductive polymer was converted into a conjugated conductive polymer in an inert atmosphere, thereby obtaining a double-layer coated micron silicon-carbon negative electrode material coated with a conjugated conductive polymer and a carbon layer.
[0069] In this embodiment 4:
[0070] The first cycle capacity-voltage curve of the prepared conjugated conductive polymer and carbon double coated micron silicon carbon negative electrode material was tested by assembling a half cell with lithium metal as the counter electrode. 1 At this current density, the battery's first cycle discharge capacity is 1934.6 mAh g- 1 The first cycle charge capacity is 1232.3mAh g- 1 , the first-cycle Coulomb efficiency is 63.7%.
[0071] The coulombic efficiency and cycling stability curves of the micronized silicon-carbon negative electrode material with double coating of conjugated conductive polymer and carbon were prepared. The half-cell was assembled with lithium metal as the counter electrode and tested. 1 At this current density, after 100 cycles, the battery has a capacity retention rate of 48.3% and a Coulombic efficiency of 97.5%.
[0072] It should be understood that the embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they cannot limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention. Although the specific implementation methods of the present invention are described in conjunction with the accompanying drawings, it is not a limitation of the scope of protection of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.
Claims
1. A method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material, characterized in that: The preparation method comprises the following steps: In the first step, micronized silicon powder is uniformly dispersed in an alcohol solution containing a carbon source to obtain a precursor solution; In the second step, the precursor solution obtained in the first step is heated to remove the alcohol solvent, and then calcined in an inert atmosphere at a high temperature to obtain carbon-coated micron silicon; In the third step, the carbon-coated micronized silicon obtained in the second step and the polymer are uniformly mixed in an organic solvent to form a slurry; In the fourth step, the slurry formed in the third step is evenly coated on the current collector, dried, and then heat-treated in an inert atmosphere to convert the conductive polymer monomer into a conjugated conductive polymer to obtain a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material.
2. The method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material according to claim 1, characterized in that: In the first step: The micron silicon powder has a particle size of 1-10 μm; The carbon source is one or more of polyacetylene, polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene)-polylactic acid, polyaniline and polyacrylonitrile; In the alcohol solution containing a carbon source, the alcohol solvent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, and ethylene glycol.
3. The method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material according to claim 1, characterized in that: In the first step: In the precursor solution, the mass ratio of micron silicon to carbon source is 1:0.5–1:5; The concentration of micronized silicon powder in the slurry is 1–5 g / ml.
4. The method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material according to claim 1, characterized in that: In the second step: The heating temperature is 80–120°C; The high temperature calcination temperature is 700-800°C, and the calcination time is 4-6 hours.
5. The method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material according to claim 1, characterized in that: In the third step: The polymer is one or more of polyacetylene, polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene)-polylactic acid, polyaniline and polyacrylonitrile; The organic solvent is one or more of N,N-dimethylformamide, acetone, methanol and dimethyl sulfoxide.
6. The method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material according to claim 1, characterized in that: In the third step: The mass ratio of the carbon-coated micronized silicon to the polymer is 1:0.1–1:1; In the slurry, the concentration of carbon-coated micro-silicon is 150-200 mg / ml.
7. The method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material according to claim 1, characterized in that: In the third step, 1 ml of slurry is applied to 25-100 cm 2 on the current collector.
8. The method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material according to claim 1, characterized in that: In the third step: The drying temperature is 80–120°C; The heat treatment temperature is 260-320°C and the heat treatment time is 1-2 h; The current collector is made of one of copper, nickel, stainless steel and carbon.
9. The method for preparing a conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material according to claim 1, characterized in that: In the second step, the inert gas is one or more of nitrogen or argon; in the fourth step, the inert gas is one or more of nitrogen or argon.
10. A conjugated conductive polymer and carbon double-coated micron silicon-carbon negative electrode material, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 9 and is used for the preparation of high-energy lithium-ion batteries.