CN115966681A - Battery self-supporting anode and preparation method and application thereof - Google Patents
Battery self-supporting anode and preparation method and application thereof Download PDFInfo
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Images
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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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- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to a self-supporting anode of a battery, a preparation method and application thereof. The invention is prepared by the following method: dissolving lignin materials in an organic solvent, adding a conductive agent and linear macromolecules, and mixing to obtain a spinning solution; preparing precursor fiber from the obtained spinning solution by utilizing electrostatic spinning; heating the precursor fiber and keeping the temperature; after cooling, heating and preserving heat in an inert gas atmosphere, then reducing the temperature, introducing silane gas, and introducing organic gas to form a soft carbon layer to obtain a product A; and washing the obtained product A, and drying to obtain the self-supporting anode of the battery. The invention takes the soft carbon as the coating to reduce the side reaction of the electrolyte and the electrode material, thereby improving the coulombic efficiency of the first circle.
Description
Technical Field
The invention relates to the technical field of sodium ion batteries, in particular to a battery self-supporting anode and a preparation method and application thereof.
Background
At present, lithium ion batteries are widely applied in the fields of 3C consumer electronics, new energy electric vehicles, renewable energy storage and the like. Limited lithium resources, unbalanced distribution and high cost thereof are not favorable for large-scale application thereof in the field of energy storage. Meanwhile, the graphite negative electrode of the commercial lithium ion battery hinders the further improvement of the cycle performance and the rate capability due to the structural characteristics of the graphite negative electrode. The sodium ion battery has an energy storage mechanism similar to that of the lithium ion battery, and is expected to replace the lithium ion battery product due to the advantages of rich resources, low cost and the like.
In order to further reduce the cost of the sodium ion battery, a negative electrode material with high specific capacity needs to be found, and in recent years, alloy negative electrode materials attract extensive attention of researchers. The Si (Si) source is rich, the theoretical capacity (954 mAh/g) is high, and meanwhile, the volume expansion rate of the Si cathode is 114% and is far smaller than that of Sn (420%), ge (369%) and P (308%) of other alloy materials. Nevertheless, in order to further improve the cycle stability, it is necessary to continue to reduce the expansion of the silicon negative electrode. In addition, the silicon negative electrode material is poor in conductivity.
The carbon nano fiber has better mechanical property and can prevent the silicon nano particles from expanding in the charging and discharging processes. Meanwhile, the carbon nanofiber can provide a continuous conductive framework, and the electronic conductivity and the ion transmission kinetics are improved. The good flexibility enables the electrode to be used as a self-supporting electrode, reduces the use of auxiliary materials such as a current collector, a binder and the like, and further reduces the cost. Therefore, it is a point of interest to design a self-supporting anode material of a reasonable high-performance silicon/carbon nanofiber sodium ion battery by utilizing the advantages of the carbon nanofibers.
Disclosure of Invention
In order to solve the technical problems, the invention provides a self-supporting anode of a battery, and a preparation method and application thereof. Silicon nano particles are uniformly loaded in carbon nano fibers through an electrostatic spinning technology and pyrolytic carbonization, and the carbon nano fibers not only serve as a substrate of a self-supporting anode, but also serve as a skeleton for supporting and loading nano silicon to increase the conductivity of the carbon nano fibers, so that the rate capability is improved. And then coating a soft carbon coating on the surface of the material. The soft carbon is used as a coating, so that the side reaction of the electrolyte and the electrode material can be reduced, and the coulomb efficiency of the first circle is improved. Further realizes the preparation of the self-supporting anode material of the high-performance silicon/carbon nano fiber sodium ion battery.
The invention aims to provide a self-supporting anode of a battery, which takes lignin-based carbon nanofibers as a supporting substrate, nano silicon is loaded on the surface of the lignin-based carbon nanofibers, and soft carbon is taken as a coating, so that a sandwich structure of lignin-based carbon nanofibers-nano silicon-soft carbon is formed.
The second purpose of the invention is to provide a preparation method of a self-supporting anode of a battery, which comprises the following steps:
(1) Dissolving lignin materials in an organic solvent, adding a conductive agent, mixing, adding linear polymers, and mixing to obtain a spinning solution;
(2) Preparing precursor fiber from the spinning solution obtained in the step (1) by utilizing electrostatic spinning;
(3) Heating the precursor fiber obtained in the step (2) to 200-250 ℃, and keeping the temperature for 2-3 h; after cooling, heating for a period of time in an inert gas atmosphere, reducing the temperature to 600-700 ℃, introducing silane gas, and introducing organic gas to form a soft carbon layer to obtain a product A;
(4) And (4) washing the product A obtained in the step (3), and drying to obtain the self-supporting anode of the battery.
In one embodiment of the present invention, in step (1), the organic solvent is selected from one or more of DMAC, acetone, dimethyl sulfoxide and tetrahydrofuran. Further, a mixed solvent of DMAC and acetone is preferred, and the mass ratio of DMAc to acetone can be 1:1-1:2; can be 1:1, 1:2, 1, 0.5, 2:3, or any mass ratio between any two values. The lignin materials can be well dissolved by utilizing the organic solvent to prepare the spinning solution.
In one embodiment of the present invention, in the step (1), the conductive agent is selected from graphene or carbon nanotubes, and the amount of the conductive agent is 0.5wt% to 1wt%. The conductive agent can improve the conductivity and strength of the material.
In one embodiment of the present invention, in the step (1), the linear polymer is one or more of carboxymethyl cellulose, hydroxyethyl cellulose, chitosan, carboxymethyl chitin, and carboxymethyl chitosan.
In one embodiment of the invention, in step (1), the lignin-based material is selected from one or more of industrial alkali lignin, lignosulfonate, sulfonated lignin, enzymatic lignin, ground wood lignin; the mass concentration of the lignin material in the spinning solution is 10wt% -25wt%, and further, can be 10wt% -15wt%,15wt% -25wt%,10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%; or any mass concentration between any two values.
In one embodiment of the invention, in the step (1), the mass ratio of the linear polymer to the lignin-based material is 1:1-1:5.
In one embodiment of the present invention, in the step (2), the conditions of the electrospinning are: the voltage is +15kV to-5 kV, the feed rate is 0.5mL/h to 2.0mL/h, and the distance between the injector and the narrowing roller is 15cm to 20cm.
In one embodiment of the invention, in step (3), the soft carbon layer has a thickness of less than 500nm.
In one embodiment of the invention, in the step (3), the heating temperature in the inert gas atmosphere is 1200-1500 ℃, the heating time is 2 h-4 h, and the heating speed is 1-3 ℃/min.
In one embodiment of the present invention, in the step (3), the silane-based gas is selected from monosilane or disilane; according to the invention, si is generated by decomposing silane gas at high temperature; the flow rate of the silane gas is 40mL/min-60mL/min.
In one embodiment of the present invention, in step (3), the organic gas is C1-C6 hydrocarbon, and the gas flow rate is 40mL/min-60mL/min. The invention utilizes the gas cracking of organic gas under the high temperature condition and realizes the carbon bond recombination on the solid surface to generate a new soft carbon layer, which can reduce the volume expansion of silicon in the charging and discharging process so as to obtain a stable electrode.
In one embodiment of the invention, the C1-C6 hydrocarbon is selected from one or more of methane, ethane, ethylene, acetylene, butyne, butadiene, pentane, heptane, cyclohexane. Further, one or more of methane, ethane, acetylene, ethylene, cyclohexane is preferable.
In one embodiment of the present invention, in the step (4), the washing solution for washing comprises hydrochloric acid, water and ethanol. The concentration of the hydrochloric acid is 1M.
A third object of the invention is to provide a sodium ion battery comprising said battery self-supporting anode.
The good conductivity, flexibility and strength of the carbon network structure interwoven by the carbon nanofibers are the basis of the material as a self-supporting material. However, the sodium storage theoretical value of the carbon nano-fiber is lower than that of transition metal, and the sodium storage performance of the carbon nano-fiber can be improved by vapor deposition of nano-silicon. The soft carbon is used as a coating to form a lignin-based carbon nanofiber-nano silicon-soft carbon sandwich structure, so that the expansion of silicon in the charging and discharging process can be reduced, and a stable electrode structure can be obtained.
Compared with the prior art, the technical scheme of the invention has the following advantages:
according to the invention, the flexible carbon nanofiber self-supporting electrode substrate is obtained through an electrostatic spinning technology, and meanwhile, nano silicon can be uniformly loaded on the carbon nanofibers through a vapor deposition method. The fine conductivity of the compact carbon nanofiber compensates the conductivity of the nano-silicon, the microstructure of the material prepared by electrostatic spinning is an interwoven fibrous structure, the interwoven fibrous structure has a pore diameter structure, the pore diameter structure is beneficial to the continuous transmission of electrons, the multiplying power performance of the silicon is improved, and the material can be used as a self-supporting electrode, so that the cost can be reduced to a great extent; the self-supporting electrode refers to that the prepared material can be used as an electrode material, and does not need an additional binder and a conductive agent or load in a current collector. Has natural advantages in cost.
The lignin-based carbon nanofiber has the defect of insufficient flexibility, and the situation can be improved by adding linear macromolecules. The carbon nano fiber mainly has a hard carbon structure, has a plurality of defect structures, and has the problem of low first-turn coulomb efficiency. According to the invention, the soft carbon layer is generated on the surface, and the soft carbon and the electrolyte are utilized to form a more stable SEI film, so that the first coulomb efficiency of the anode can be effectively improved. Meanwhile, the formed soft carbon and carbon nanofiber interlayer wraps the silicon structure, so that the expansion of Si can be further reduced, and long-cycle stability is obtained.
Drawings
In order that the present disclosure may be more readily and clearly understood, reference will now be made in detail to the present disclosure, examples of which are illustrated in the accompanying drawings, wherein,
FIG. 1 is a schematic cross-sectional view of a high-rate soft carbon-coated silicon/carbon nanofiber sodium-ion battery self-supporting anode material according to an embodiment of the present invention;
description reference numbers indicate: 1. a carbon nanofiber substrate; 2. a nano silicon layer; 3. a soft carbon layer.
Detailed Description
The present invention is further described below in conjunction with the drawings and the embodiments so that those skilled in the art can better understand the present invention and can carry out the present invention, but the embodiments are not to be construed as limiting the present invention.
Example 1
The embodiment of the invention provides a preparation method of a silicon/carbon nanofiber sodium ion battery self-supporting anode material taking soft carbon as a coating, which comprises the following steps:
(1) 3 g lignin was dissolved in 24g of a mixed solution of DMAc and acetone (w/w 1:1), stirred overnight, 0.3 g graphene oxide was added, and stirring was continued for 12 h. Then 3 g carboxymethyl chitin is added to continue stirring 12 h, and an electrostatic spinning solution is obtained.
(2) And (3) placing the electrostatic spinning solution into an injector of an electrostatic spinning machine for electrostatic spinning to prepare precursor fiber. The electrospinning operating voltage was 20 kV (+ 15kV and-5 kV), the feed rate was 1.0 mL/h, and the injector-to-collector roll spacing was 18 cm.
(3) And (3) placing the precursor fiber prepared in the step (2) in a muffle furnace, heating to 250 ℃ at a heating rate of 1 ℃/min, and preserving heat for 2 h. Transferring the mixture to a tube furnace after temperature reduction, heating to 1300 ℃ at the heating speed of 2 ℃/min under the helium atmosphere, preserving the temperature of 2h, then reducing the temperature to 650 ℃, introducing monosilane gas at the air flow speed of 40mL/min, introducing methane gas at the air flow speed of 40mL/min to 4 h after 4 h, and obtaining a product A.
(4) And (4) washing the product A obtained in the step (3) with 1M hydrochloric acid, water and ethanol in sequence, and drying to obtain a final product, namely the 3D porous silicon-carbon composite material, namely the self-supporting anode of the sodium ion battery.
Example 2
The embodiment of the invention provides a preparation method of a silicon/carbon nanofiber sodium ion battery self-supporting anode material taking soft carbon as a coating, which comprises the following steps:
(1) 3 g lignin was dissolved in 24g of a mixed solution of DMAc and acetone (w/w 1:1), stirred overnight, 0.3 g graphene oxide was added, and stirring was continued for 12 h. Then 2 g carboxymethyl chitin is added to continue stirring 12 h, and an electrostatic spinning solution is obtained.
(2) And (3) placing the electrostatic spinning solution into an injector of an electrostatic spinning machine for electrostatic spinning to prepare precursor fiber. The electrospinning operating voltage was 20 kV (+ 15kV and-5 kV), the feed rate was 1.0 mL/h, and the injector-to-collector roll spacing was 18 cm.
(3) And (3) placing the precursor fiber prepared in the step (2) in a muffle furnace, heating to 250 ℃ at a heating rate of 1 ℃/min, and preserving heat for 2 h. Transferring to a tube furnace after temperature reduction, heating to 1300 ℃ at a heating speed of 2 ℃/min under the helium atmosphere, preserving heat for 2h, then reducing the temperature to 650 ℃, introducing disilane gas at an airflow speed of 50 mL/min, introducing methane gas 4 h at an airflow speed of 40mL/min after 4 h, and obtaining a product A.
(4) And (4) washing the product A obtained in the step (3) with 1M hydrochloric acid, water and ethanol in sequence, and drying to obtain a final product, namely the 3D porous silicon-carbon composite material, namely the self-supporting anode of the sodium ion battery.
Example 3
The embodiment of the invention provides a preparation method of a silicon/carbon nanofiber sodium ion battery self-supporting anode material taking soft carbon as a coating, which comprises the following steps:
(1) 3 g lignin was dissolved in 24g of a mixed solution of DMAc and acetone (w/w 1:1), stirred overnight, 0.3 g graphene oxide was added, and stirring was continued for 12 h. 2 g hydroxyethyl cellulose was then added and stirring continued for 12 h to give an electrospun solution.
(2) And (3) placing the electrostatic spinning solution into an injector of an electrostatic spinning machine for electrostatic spinning to prepare precursor fiber. The electrospinning operating voltage was 20 kV (+ 15kV and-5 kV), the feed rate was 1.0 mL/h, and the injector-to-collector roll spacing was 18 cm.
(3) And (3) putting the precursor fiber prepared in the step (2) into a muffle furnace, heating to 250 ℃ at a heating rate of 1 ℃/min, and preserving heat for 2 h. Transferring the mixture to a tubular furnace after temperature reduction, heating to 1300 ℃ at the heating speed of 2 ℃/min under the helium atmosphere, preserving the temperature of 2h, then reducing the temperature to 650 ℃, introducing monosilane gas at the airflow speed of 40mL/min, introducing 4 h, and introducing methane gas at the airflow speed of 60mL/min to obtain a product A, wherein the temperature of the mixture is 4 h.
(4) And (4) washing the product A obtained in the step (3) with 1M hydrochloric acid, water and ethanol in sequence, and drying to obtain a final product, namely the 3D porous silicon-carbon composite material, namely the self-supporting anode of the sodium ion battery.
Example 4
The embodiment of the invention provides a preparation method of a silicon/carbon nanofiber sodium ion battery self-supporting anode material taking soft carbon as a coating, which comprises the following steps:
(1) 4g lignin was dissolved in 24g mixed solution of DMAc and acetone (w/w 1:1), stirred overnight, 0.3 g graphene oxide was added and stirring was continued for 12 h. 3 g hydroxyethyl cellulose was then added and stirring continued for 12 h to give an electrospun solution.
(2) And (3) placing the electrostatic spinning solution into an injector of an electrostatic spinning machine for electrostatic spinning to prepare precursor fiber. The electrospinning operating voltage was 20 kV (+ 15 and-5 kV), the feed rate was 1.0 mL/h, and the injector-to-collector roll spacing was 18 cm.
(3) And (3) putting the precursor fiber prepared in the step (2) into a muffle furnace, heating to 250 ℃ at a heating rate of 1 ℃/min, and preserving heat for 2 h. Transferring the mixture to a tube furnace after temperature reduction, raising the temperature to 1400 ℃ at a temperature raising speed of 1 ℃/min under the helium atmosphere, preserving the temperature for 2h, then lowering the temperature to 650 ℃, introducing disilane gas at an airflow speed of 40mL/min, introducing 4 h, and then introducing methane gas at an airflow speed of 60mL/min for 4 h to obtain a product A.
(4) And (4) washing the product A obtained in the step (3) with 1M hydrochloric acid, water and ethanol in sequence, and drying to obtain a final product, namely the 3D porous silicon-carbon composite material, namely the self-supporting anode of the sodium ion battery.
Comparative example 1
The comparative example provides a preparation method of a silicon/carbon nanofiber composite material, which comprises the following specific steps:
(1) 3 g lignin was dissolved in 24g of a mixed solution of DMAc and acetone (w/w 1:1), stirred overnight, 0.3 g graphene oxide was added, and stirring was continued for 12 h. Then 3 g carboxymethyl chitin is added to continue stirring 12 h, and an electrostatic spinning solution is obtained.
(2) And (2) placing the electrostatic spinning solution obtained in the step (1) into an injector of an electrostatic spinning machine for electrostatic spinning to prepare precursor fiber. The electrospinning operating voltage was 20 kV (+ 15 and-5 kV), the feed rate was 1.0 mL/h, and the injector-to-collector roll spacing was 18 cm.
(3) And (3) placing the precursor fiber prepared in the step (2) in a muffle furnace, heating to 250 ℃ at a heating rate of 1 ℃/min, and preserving heat for 2 h. Transferring the mixture to a tubular furnace after cooling, heating to 1300 ℃ at the heating rate of 2 ℃/min under the helium atmosphere, preserving the heat of 2h, then reducing the temperature to 650 ℃, introducing silane gas 4 h at the gas flow rate of 40mL/min, and obtaining a product A.
(4) And (4) washing the product A obtained in the step (3) with 1M hydrochloric acid, water and ethanol in sequence, and drying to obtain a final product, namely the silicon/carbon nanofiber composite material.
Comparative example 2
The comparative example provides a preparation method of a silicon/carbon nanofiber composite material, which comprises the following specific steps:
(1) 3 g lignin was dissolved in a mixed solution of 24g DMAc and acetone (w/w is 1:1), stirred overnight, 0.3 g graphene oxide was added, and stirring was continued for 12 h to obtain an electrospinning solution.
(2) And (2) placing the electrostatic spinning solution obtained in the step (1) into an injector for electrostatic spinning to prepare precursor fiber. The electrospinning operating voltage was 20 kV (+ 15 and-5 kV), the feed rate was 1.0 mL/h, and the injector-to-collector roll spacing was 18 cm.
(3) And (3) placing the precursor fiber prepared in the step (2) in a muffle furnace, heating to 250 ℃ at a heating rate of 1 ℃/min, and preserving heat for 2 h. Transferring to a tube furnace after temperature reduction, heating to 1300 ℃ at a heating speed of 2 ℃/min under the helium atmosphere, preserving heat for 2h, then reducing the temperature to 650 ℃, introducing silane gas 4 h at an airflow speed of 40mL/min, and then introducing methane gas 4 h at an airflow speed of 40mL/min to obtain a product A.
(4) And (4) washing the product A obtained in the step (3) with 1M hydrochloric acid, water and ethanol in sequence, and drying to obtain a final product, namely the silicon/carbon nanofiber composite material.
Test example
(1) 3D porous silicon-carbon composites prepared in examples 1-4 and silicon/carbon nanofiber composites prepared in comparative examples 1 and 2 were used as self-supporting negative electrode materials as negative electrodes and metal sodium sheets as positive electrodes, and 1.0 mol/L LiPF was used 6 The solution was an electrolyte (wherein the solvent of the electrolyte was EC (ethylene carbonate), DMC (dimethyl carbonate) and FEC (fluoroethylene carbonate), and the volume ratio of EC, DMC and FEC was 4.5. GCD was tested using a blue cell test system at a voltage window of 0.01V-2.5V, with the following test conditions and results: the button cell is sequentially subjected to constant-current charge and discharge tests under the conditions that the current density is 50 mA/g, 100 mA/g, 200 mA/g, 500 mA/g, 1000 mA/g, 1500 mA/g and 100 mA/g, and the voltage interval is 0V-1.5V. The results are shown in tables 1 and 2.
TABLE 1 initial discharge capacity and initial coulombic efficiency of button half-cell of sodium ion self-supporting electrode materials obtained in examples 1-4 and comparative example 1
As shown in table 1, the button half cells made of the self-supporting material for the negative electrodes of the sodium ion batteries prepared in examples 1 to 4 and comparative example 1 all have higher initial discharge capacity (more than 750 mAh/g), but the first-turn coulombic efficiency of comparative example 1 is lower (less than 70%), and the first-turn coulombic efficiency of example 1~4 is greater than 75%. As can be seen from table 2, the button half cell of the sodium ion self-supporting electrode material prepared in example 1~4 has higher capacity under different current densities, and can recover to be close to the initial capacity after being charged and discharged with large current, and shows excellent rate capability. The rate cycle performance of the half-cell obtained by the sodium ion self-supporting electrode material obtained in the comparative example 1 or the comparative example 2 is poor, and the discharge capacity is low.
TABLE 2 button half-cell rate cycling capacities of the self-supporting electrode materials from examples 1-4 and comparative example 1
(2) And (3) carrying out constant-current charge and discharge test on the button cell obtained in the step (1) at the current density of 100 mA/g, wherein the voltage interval is 0V-1.5V, and after circulation for 200, testing the capacity retention rate of the cell, wherein the test result is shown in table 3.
TABLE 3 Capacity Retention ratio after 200 cycles of button half-cell cycle of self-supporting anode composite electrode material for sodium ion battery obtained in examples 1-4 and comparative example 1
As can be seen from table 3, the button half cells of the self-supporting anode of the high-rate silicon/carbon nanofiber sodium ion battery prepared in examples 1 to 4 and using soft carbon as a coating all have high cycle retention rate (greater than 90%), and have excellent cycle stability. The capacity retention rates of comparative example 1 and comparative example 2 were only 88.6% and 90.7%. Therefore, the structure that the soft carbon and carbon nanofiber interlayer formed in the embodiment of the invention wraps silicon can further reduce the expansion of Si, and can remarkably improve the multiplying power cycle capacity of the battery so as to obtain long cycle stability.
The invention is not limited to the above examples, and one or a combination of several examples may also achieve the object of the invention.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (10)
1. The battery self-supporting anode is characterized in that lignin-based carbon nanofibers are used as a supporting substrate, nano silicon is loaded on the surfaces of the lignin-based carbon nanofibers, and soft carbon is used as a coating to form a lignin-based carbon nanofiber-nano silicon-soft carbon sandwich structure.
2. A preparation method of a self-supporting anode of a battery is characterized by comprising the following steps:
(1) Dissolving lignin materials in an organic solvent, adding a conductive agent and linear macromolecules, and mixing to obtain a spinning solution;
(2) Preparing precursor fiber from the spinning solution obtained in the step (1) by utilizing electrostatic spinning;
(3) Heating the precursor fiber obtained in the step (2) to 200-250 ℃, and keeping the temperature for 2-3 h; heating for a period of time in an inert gas atmosphere, reducing the temperature to 600-700 ℃, introducing silane gas, and introducing organic gas to form a soft carbon layer to obtain a product A;
(4) And (4) washing the product A obtained in the step (3), and drying to obtain the self-supporting anode of the battery.
3. The method according to claim 2, wherein in step (1), the organic solvent is one or more selected from the group consisting of DMAC, acetone, dimethyl sulfoxide and tetrahydrofuran.
4. The method according to claim 2, wherein the conductive agent is used in an amount of 0.5wt% to 1wt% in the step (1).
5. The production method according to claim 2, wherein in the step (1), at least one of the following conditions is satisfied:
1) The linear polymer is one or more of carboxymethyl cellulose, hydroxyethyl cellulose, chitosan, carboxymethyl chitin and carboxymethyl chitosan;
2) The lignin material is selected from one or more of industrial alkali lignin, lignosulphonate, sulfonated lignin, enzymatic hydrolysis lignin and ground wood lignin;
3) The mass concentration of the lignin materials in the spinning solution is 10-25 wt%;
4) And the mass ratio of the linear polymer to the lignin material is 1:1-1:5.
6. The production method according to claim 2, wherein in the step (2), the conditions of the electrospinning are: the voltage is between +15kV and-5 kV, the feeding rate is between 0.5mL/h and 2.0mL/h, and the distance between the injector and the narrowing roller is between 15cm and 20cm.
7. The method according to claim 2, wherein in the step (3), the soft carbon layer has a thickness of less than 500nm.
8. The method according to claim 2, wherein the flow rate of the silane-based gas in step (3) is 40 to 60mL/min.
9. The method according to claim 2, wherein in the step (3), the organic gas is C1-C6 hydrocarbon, and the gas flow rate is 40mL/min-60mL/min.
10. A sodium ion battery comprising the battery self-supporting anode of claim 1 or the battery self-supporting anode prepared by the preparation method of any one of claims 2 to 9.
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