CN117038875A - Method for coating surface of silicon-carbon composite anode material with nitrogen-doped carbon - Google Patents
Method for coating surface of silicon-carbon composite anode material with nitrogen-doped carbon Download PDFInfo
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- CN117038875A CN117038875A CN202310859419.1A CN202310859419A CN117038875A CN 117038875 A CN117038875 A CN 117038875A CN 202310859419 A CN202310859419 A CN 202310859419A CN 117038875 A CN117038875 A CN 117038875A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 39
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 37
- 239000011870 silicon-carbon composite anode material Substances 0.000 title claims abstract description 36
- 239000011248 coating agent Substances 0.000 title claims abstract description 18
- 238000000576 coating method Methods 0.000 title claims abstract description 18
- 238000000034 method Methods 0.000 title claims abstract description 18
- KAESVJOAVNADME-UHFFFAOYSA-N Pyrrole Chemical compound C=1C=CNC=1 KAESVJOAVNADME-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000002153 silicon-carbon composite material Substances 0.000 claims abstract description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000011247 coating layer Substances 0.000 claims abstract description 23
- 239000000463 material Substances 0.000 claims abstract description 20
- 239000008367 deionised water Substances 0.000 claims abstract description 19
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 19
- 238000003756 stirring Methods 0.000 claims abstract description 17
- 239000002243 precursor Substances 0.000 claims abstract description 14
- FBAFATDZDUQKNH-UHFFFAOYSA-M iron chloride Chemical compound [Cl-].[Fe] FBAFATDZDUQKNH-UHFFFAOYSA-M 0.000 claims abstract description 9
- 239000002244 precipitate Substances 0.000 claims abstract description 9
- 238000011049 filling Methods 0.000 claims abstract description 7
- 239000005457 ice water Substances 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims abstract description 7
- 239000000203 mixture Substances 0.000 claims abstract description 7
- 238000001291 vacuum drying Methods 0.000 claims abstract description 7
- 238000005406 washing Methods 0.000 claims abstract description 7
- 238000005303 weighing Methods 0.000 claims abstract description 7
- 230000001376 precipitating effect Effects 0.000 claims abstract description 3
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 14
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 14
- 239000000725 suspension Substances 0.000 claims description 12
- 239000007787 solid Substances 0.000 claims description 9
- 238000003763 carbonization Methods 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 10
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052744 lithium Inorganic materials 0.000 abstract description 8
- 239000010405 anode material Substances 0.000 abstract description 4
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 4
- 230000002035 prolonged effect Effects 0.000 abstract description 4
- 238000010000 carbonizing Methods 0.000 abstract 1
- 238000006116 polymerization reaction Methods 0.000 description 12
- 239000007800 oxidant agent Substances 0.000 description 11
- 230000001590 oxidative effect Effects 0.000 description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- -1 iron ions Chemical class 0.000 description 5
- 239000002210 silicon-based material Substances 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 230000007847 structural defect Effects 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 3
- 239000011868 silicon-carbon composite negative electrode material Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 239000003575 carbonaceous material Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 239000005543 nano-size silicon particle Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000009751 slip forming Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
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- Manufacturing & Machinery (AREA)
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Abstract
The invention discloses a method for coating nitrogen-doped carbon on the surface of a silicon-carbon composite anode material, which belongs to the technical field of anode materials of lithium ion batteries and comprises the following steps: (1) Weighing pyrrole and silicon-carbon composite material according to the formula, adding the pyrrole and silicon-carbon composite material into deionized water, and stirring and mixing uniformly; (2) Placing the solution prepared in the step (1) into a water bath kettle of an ice-water mixture, and adding an iron chloride solution; (3) Adding the solution obtained in the step (2) into a centrifuge, centrifuging and precipitating, collecting precipitate, washing and vacuum drying to obtain a precursor material; (4) And (3) filling the precursor material obtained in the step (3) into a crucible, placing the crucible in a vacuum furnace, and carbonizing the crucible at constant temperature and oxygen-free for 4-6 hours to obtain the silicon-carbon composite anode material with the nitrogen-doped carbon coating layer on the surface. According to the method for coating the surface of the silicon-carbon composite anode material by doping nitrogen and carbon, the conductivity is improved, so that the coating layer has better mechanical properties, the lithium storage performance of the material is improved, and the cycle life is prolonged.
Description
Technical Field
The invention relates to the technical field of lithium ion battery anode materials, in particular to a method for coating nitrogen-doped carbon on the surface of a silicon-carbon composite anode material.
Background
Silicon is used as a lithium ion battery anode material, has the advantage of high lithium storage capacity, and is the first choice of a new generation of high-capacity lithium ion anode material. However, the silicon material has volume expansion exceeding 300% in the lithium intercalation process, so that particles are easily pulverized, an electrode structure is unstable, side reactions with electrolyte are increased, a new SEI film is continuously formed, and the cycle life is poor. In addition, the conductivity of the semiconductor is further improved in the case of silicon materials. The method commonly used at present is to nano silicon and compound the nano silicon with a carbon material to prepare a silicon-carbon composite anode material for use. Graphite is a carbon negative electrode material which is commercially applied in a large scale in a lithium ion battery, the actual lithium storage capacity of the graphite is close to the theoretical lithium storage capacity, the capacity is further improved to a limited extent, and the performance is unstable. At present, the surface of the silicon-carbon material is mainly coated with carbon, the performance of the carbon coating layer seriously affects the circulation stability of the material, and the carbon coating layer doped with nitrogen element forms structural defects due to atom doping, so that the mechanical stability of the coating layer is improved, the volume change of the material is better adapted, the material is not easy to break, more channels can be provided for the transmission of lithium ions, and the better circulation life is facilitated.
Disclosure of Invention
The invention aims to provide a method for coating nitrogen-doped carbon on the surface of a silicon-carbon composite anode material, which is characterized in that the surface of the silicon-carbon composite anode material is modified by a nitrogen-doped carbon coating layer, so that the conductivity is improved, the coating layer has better mechanical properties, can better adapt to the volume change of the silicon material, and meanwhile, the nitrogen-doped carbon coating layer formed on the surface has structural defects, so that more electrochemical active sites are provided for the transmission and diffusion of lithium ions, the lithium storage performance of the material is improved, and the cycle life is prolonged.
In order to achieve the above purpose, the invention provides a method for coating nitrogen-doped carbon on the surface of a silicon-carbon composite anode material, which comprises the following steps:
(1) Weighing pyrrole and silicon-carbon composite material according to the formula, adding the pyrrole and the silicon-carbon composite material into deionized water, stirring and mixing uniformly, and controlling the solid content of the silicon-carbon composite material to be within 2-5wt.% in order to ensure the coating uniformity, wherein the addition amount of the pyrrole is 2-16wt.% of the silicon-carbon composite material;
(2) Placing the solution prepared in the step (1) into a water bath kettle of an ice-water mixture, adding an iron chloride solution with the concentration of 1wt.% as an oxidant, and continuously stirring for 6-12 hours to enable pyrrole to perform polymerization reaction on the surface of the silicon-carbon composite material;
(3) Adding the solution obtained in the step (2) into a centrifuge, centrifuging and precipitating at a speed of 1000-3000 rpm, collecting precipitate, washing and vacuum drying to obtain a precursor material;
(4) And (3) filling the precursor material obtained in the step (3) into a crucible, placing the crucible in a vacuum furnace, controlling the heating speed to be 3-5 ℃/min, and performing anaerobic carbonization for 4-6 hours at the constant temperature of 800-1000 ℃ to obtain the silicon-carbon composite anode material with the nitrogen-doped carbon coating layer on the surface.
Preferably, in the preparation of the silicon-carbon composite material in the step (1), deionized water is firstly used for preparing a silicon-carbon composite anode material suspension with the solid content of 2-5 wt%, and 2-16wt.% of pyrrole of the silicon-carbon composite material is added into the suspension as a nitrogen source and a carbon source of the nitrogen-doped carbon coating layer according to requirements.
Preferably, in the step (1), the addition amount of pyrrole is controlled according to the coating amount requirement.
Preferably, in the step (2), in order to ensure the polymerization reaction is complete, an iron chloride solution with the concentration of 1wt.% is used as an oxidant to promote the polymerization of pyrrole on the surface of the silicon-carbon composite material, and the addition amount of the iron chloride solution is 1.5 times that of pyrrole.
Preferably, in the step (3), the collected precipitate is repeatedly washed with deionized water for 3 to 5 times to remove residual iron ions and chloride ions.
Therefore, the method for coating the nitrogen-doped carbon on the surface of the silicon-carbon composite anode material is characterized in that pyrrole is used as a nitrogen source and a carbon source of the nitrogen-doped carbon coating layer, ferric chloride solution is used as an oxidant to promote the polymerization of pyrrole on the surface of the silicon-carbon composite material, and the nitrogen-doped carbon coating layer is modified on the surface of the silicon-carbon composite material to improve conductivity, so that the coating layer has better mechanical properties, can better adapt to the volume change of the silicon material, and meanwhile, the nitrogen-doped carbon coating layer formed on the surface has structural defects, so that more electrochemical active sites are provided for the transmission and diffusion of lithium ions, the lithium storage performance of the material is improved, and the cycle life is prolonged.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 is an SEM and energy spectrum of a silicon carbon composite anode material of the present invention;
FIG. 2 is a cycle life curve of the silicon carbon composite material prepared in example 1 and comparative example 1 of the present invention.
Detailed Description
The technical scheme of the invention is further described below through the attached drawings and the embodiments.
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention.
The invention provides a method for coating nitrogen-doped carbon on the surface of a silicon-carbon composite negative electrode material, which is characterized in that the nitrogen-doped carbon is coated on the surface of the silicon-carbon composite material, so that the cycle performance of the material is obviously improved. Fig. 1 is an SEM and energy spectrum of the silicon carbon composite anode material of the present invention.
Example 1
(1) Firstly, weighing 50g of silicon-carbon composite anode material, adding the silicon-carbon composite anode material into deionized water, stirring to prepare a suspension with 3wt.% of solid content, and then adding 3g of pyrrole into the suspension, stirring and uniformly mixing, wherein the addition amount of the pyrrole is 6wt.% of the silicon-carbon composite material;
(2) Adding 4.5g of ferric chloride into deionized water, preparing an iron chloride solution with the concentration of 1wt.% as an oxidant, and in order to ensure the completion of the polymerization reaction, adding the oxidant ferric chloride with the addition amount of 1.5 times that of pyrrole, then placing the solution prepared in the step (1) into a water bath kettle of an ice-water mixture, slowly adding the prepared ferric chloride solution, and continuously stirring for reacting for 12 hours to enable the pyrrole to perform the polymerization reaction on the surface of the silicon-carbon composite material;
(3) Adding the solution obtained in the step (2) into a centrifuge for centrifugal precipitation at the speed of 3000 rpm, repeatedly washing the collected precipitate with deionized water for 3-5 times, removing residual iron ions and chloride ions, and carrying out vacuum drying to obtain a precursor material;
(4) Filling the precursor obtained in the step (3) into a crucible, placing the crucible in a vacuum furnace, controlling the heating speed to be 3 ℃/min, and carrying out anaerobic carbonization for 4 hours at the constant temperature of 800 ℃ to obtain the silicon-carbon composite anode material with the nitrogen-doped carbon coating layer on the surface;
example 2
(1) Firstly, weighing 50g of silicon-carbon composite anode material, adding the silicon-carbon composite anode material into deionized water, stirring to prepare a suspension with 3wt.% of solid content, and then adding 1g of pyrrole into the suspension, stirring and uniformly mixing, wherein the addition amount of the pyrrole is 2wt.% of the silicon-carbon composite material;
(2) Adding 1.5g of ferric chloride into deionized water, preparing an iron chloride solution with the concentration of 1wt.% as an oxidant, and placing the solution prepared in the step (1) into a water bath kettle of an ice-water mixture, slowly adding the prepared ferric chloride solution, and continuously stirring for reacting for 12 hours to enable pyrrole to perform polymerization on the surface of the silicon-carbon composite material in order to ensure that the polymerization reaction is complete, wherein the addition amount of the ferric chloride as an oxidant is 1.5 times that of pyrrole;
(3) Adding the solution obtained in the step (2) into a centrifuge for centrifugal precipitation at the speed of 3000 rpm, repeatedly washing the collected precipitate with deionized water for 3-5 times, removing residual iron ions and chloride ions, and carrying out vacuum drying to obtain a precursor material;
(4) Filling the precursor obtained in the step (3) into a crucible, placing the crucible in a vacuum furnace, controlling the heating speed to be 3 ℃/min, and carrying out anaerobic carbonization for 4 hours at the constant temperature of 800 ℃ to obtain the silicon-carbon composite anode material with the nitrogen-doped carbon coating layer on the surface;
example 3
(1) Firstly, weighing 50g of silicon-carbon composite anode material, adding the silicon-carbon composite anode material into deionized water, stirring to prepare a suspension with a solid content of 5 wt%, and then adding 5g of pyrrole into the suspension, stirring and uniformly mixing, wherein the addition amount of the pyrrole is 10 wt% of the silicon-carbon composite material;
(2) Adding 7.5g of ferric chloride into deionized water, preparing an iron chloride solution with the concentration of 1wt.% as an oxidant, and in order to ensure the completion of the polymerization reaction, adding the oxidant ferric chloride with the addition amount of 1.5 times that of pyrrole, then placing the solution prepared in the step (1) into a water bath kettle of an ice-water mixture, slowly adding the prepared ferric chloride solution, and continuously stirring for reacting for 12 hours to enable the pyrrole to perform the polymerization reaction on the surface of the silicon-carbon composite material;
(3) Adding the solution obtained in the step (2) into a centrifuge for centrifugal precipitation at the speed of 2000 rpm, repeatedly washing the collected precipitate with deionized water for 3-5 times, removing residual iron ions and chloride ions, and carrying out vacuum drying to obtain a precursor material;
(4) Filling the precursor obtained in the step (3) into a crucible, placing the crucible in a vacuum furnace, controlling the heating speed to be 5 ℃/min, and carrying out anaerobic carbonization for 6 hours at the constant temperature of 1000 ℃ to obtain the silicon-carbon composite anode material with the nitrogen-doped carbon coating layer on the surface;
example 4
(1) Firstly, weighing 50g of silicon-carbon composite anode material, adding the silicon-carbon composite anode material into deionized water, stirring to prepare a suspension with the solid content of 2 wt%, and then adding 8g of pyrrole into the suspension, stirring and uniformly mixing, wherein the addition amount of the pyrrole is 16 wt% of the silicon-carbon composite material;
(2) Adding 12g of ferric chloride into deionized water, preparing an iron chloride solution with the concentration of 1wt.% as an oxidant, and placing the solution prepared in the step (1) into a water bath kettle of an ice-water mixture, slowly adding the prepared ferric chloride solution, and continuously stirring for reaction for 6 hours to enable pyrrole to perform polymerization reaction on the surface of the silicon-carbon composite material in order to ensure that the polymerization reaction is complete, wherein the addition amount of the ferric chloride as an oxidant is 1.5 times that of pyrrole;
(3) Adding the solution obtained in the step (2) into a centrifuge for centrifugal precipitation at the speed of 1000 revolutions per minute, repeatedly washing the collected precipitate with deionized water for 3-5 times, removing residual iron ions and chloride ions, and carrying out vacuum drying to obtain a precursor material;
(4) Filling the precursor obtained in the step (3) into a crucible, placing the crucible in a vacuum furnace, controlling the heating speed to be 5 ℃/min, and performing anaerobic carbonization at the constant temperature of 900 ℃ for 6 hours to obtain the silicon-carbon composite anode material with the nitrogen-doped carbon coating layer on the surface;
comparative example 1
The silicon-carbon composite anode material in example 1 was assembled into 2032 button cell test cycle life according to the lithium ion cell button half cell assembly procedure, the material performance data are shown in table 1, and the capacity retention curve is shown in fig. 2.
The silicon-carbon composite anode material with the nitrogen-doped coating layer on the surface prepared in the embodiment is assembled into 2032 button cell test cycle life according to the button cell assembly flow, the material performance data are shown in table 1, and the capacity retention rate curve is shown in fig. 2. The test method of the battery cycle performance comprises the following steps: firstly, discharging to 0.01v at a current density of 100mA/g, then discharging to 0.005v at a current of 10mA/g, standing for 3min, and then charging to 1.5v at a current density of 100mA/g, thereby testing the cycle performance as a cycle.
Table 1:
therefore, the method for coating the surface of the silicon-carbon composite negative electrode material with nitrogen-doped carbon further improves the performance of the silicon-carbon composite negative electrode material; the nitrogen-doped carbon coating layer is modified on the surface of the silicon-carbon composite material, so that the conductivity is improved, the coating layer has better mechanical properties, the volume change of the silicon material can be better adapted, meanwhile, the structural defect of the nitrogen-doped carbon coating layer formed on the surface provides more electrochemical active sites for the transmission and diffusion of lithium ions, the lithium storage performance of the material is improved, and the cycle life is prolonged.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting it, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that: the technical scheme of the invention can be modified or replaced by the same, and the modified technical scheme cannot deviate from the spirit and scope of the technical scheme of the invention.
Claims (5)
1. The method for coating the surface of the silicon-carbon composite anode material with the nitrogen-doped carbon is characterized by comprising the following steps of:
(1) Weighing pyrrole and silicon-carbon composite material according to a formula, adding the pyrrole and the silicon-carbon composite material into deionized water, stirring and mixing uniformly, and controlling the solid content of the silicon-carbon composite material to be within 2-5wt.%, wherein the addition amount of the pyrrole is 2-16wt.% of the silicon-carbon composite material;
(2) Placing the solution prepared in the step (1) into a water bath kettle of an ice-water mixture, adding an iron chloride solution with the concentration of 1wt.% and continuously stirring for 6-12 hours;
(3) Adding the solution obtained in the step (2) into a centrifuge, centrifuging and precipitating at a speed of 1000-3000 rpm, collecting precipitate, washing and vacuum drying to obtain a precursor material;
(4) And (3) filling the precursor material obtained in the step (3) into a crucible, placing the crucible in a vacuum furnace, controlling the heating speed to be 3-5 ℃/min, and performing anaerobic carbonization for 4-6 hours at the constant temperature of 800-1000 ℃ to obtain the silicon-carbon composite anode material with the nitrogen-doped carbon coating layer on the surface.
2. The method for coating the surface of the silicon-carbon composite anode material with nitrogen-doped carbon according to claim 1, which is characterized in that: in the step (1), firstly preparing a silicon-carbon composite anode material suspension with the solid content of 2-5wt.% by using deionized water, and adding pyrrole with the solid content of 2-16wt.% of the silicon-carbon composite material into the suspension according to requirements.
3. The method for coating the surface of the silicon-carbon composite anode material with nitrogen-doped carbon according to claim 2, which is characterized in that: in the step (1), the addition amount of pyrrole is controlled according to the coating amount requirement.
4. The method for coating the surface of the silicon-carbon composite anode material with nitrogen-doped carbon according to claim 3, which is characterized by comprising the following steps: in the step (2), the addition amount of the ferric chloride solution is 1.5 times of that of pyrrole.
5. The method for coating the surface of the silicon-carbon composite anode material with nitrogen-doped carbon according to claim 4, which is characterized in that: in the step (3), the collected precipitate is repeatedly washed with deionized water for 3-5 times.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310859419.1A CN117038875A (en) | 2023-07-13 | 2023-07-13 | Method for coating surface of silicon-carbon composite anode material with nitrogen-doped carbon |
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| CN202310859419.1A CN117038875A (en) | 2023-07-13 | 2023-07-13 | Method for coating surface of silicon-carbon composite anode material with nitrogen-doped carbon |
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