CN114975908A - Tin/carbon nano lithium battery negative electrode material and preparation method thereof - Google Patents
Tin/carbon nano lithium battery negative electrode material and preparation method thereof Download PDFInfo
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- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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Abstract
The invention discloses a preparation method of a tin/carbon nano lithium battery negative electrode material, which comprises the following steps: 1) mixing tin acetate and PAN, adding a solvent for dissolving, and stirring at a constant temperature to obtain a spinning solution; 2) adding the spinning solution into a propeller, spinning by using electrostatic spinning equipment, and drying to obtain a tin/carbon nanofiber precursor; 3) carrying out cryogenic treatment on the tin/carbon nanofiber precursor obtained in the step 2) by using liquid nitrogen; 4) and carbonizing the subzero treated tin/carbon nanofiber precursor obtained in the step 3) to obtain the tin/carbon nano lithium battery negative electrode material. According to the invention, the tin/carbon nanofiber is subjected to shape reconstruction by utilizing the electrostatic spinning and cryogenic treatment processes, so that the nanofiber with a pore structure and a skin-core structure is manufactured, and the defects of volume expansion and structure collapse of the nanofiber serving as a lithium battery negative electrode material are effectively relieved, thereby inhibiting the capacity loss.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a preparation method of a tin-based lithium ion battery cathode material.
Background
Since the twenty-first century, the development of lithium ion batteries has greatly promoted the development of electric vehicles and intelligent networking, and the life style of people is deeply influenced, so people are dedicated to developing a more novel, more environment-friendly, safer, renewable and high-energy-density battery cathode material, wherein a carbon material is the most widely used lithium ion battery cathode material at present, but the theoretical capacity and safety problems of the carbon material cannot meet the requirements of the current technological development, and further the further development of the carbon material as the cathode material is limited. Therefore, on the basis of the prior art, people search and modify the cathode material, including lithium titanate Li 4 Ti 5 O n Negative electrode material, silicon-based negative electrode material, transition metal oxide material, etc., wherein the tin-based material has high specific capacity (Sn and SnO) 2 994 mAh/g and 1494mAh/g), the lithium intercalation and deintercalation voltage is moderate, the natural reserve is rich, the price is low, the lithium intercalation and deintercalation material is non-toxic, high in safety, environment-friendly and the like, and is one of candidate materials of the next generation of cathode materials. However, the tin-based material is prone to structural collapse and material pulverization during charging and discharging processes, resulting in poor cycle performance. Therefore, modification of the tin-based anode material is required. Many scholars modify the tin-based negative electrode material by methods such as carbon/graphene coating, nanocrystallization design, metal/nonmetal ion doping and the like, so that the volume expansion generated in the charging and discharging processes is slowed down, the structure is stabilized, and the electrochemical performance is improved. The carbon or graphene and the tin-based material are combined to form the composite material, and the advantages of different components are cooperated, so that the electrochemical performance of the tin-based material is integrally improved; the nano material has small particles and large specific surface area, so that more electrolyte can contact the electrode material, more diffusion flux of lithium ions on the surface of the electrode can be provided, more active sites can be provided, and the specific volume of the active material can be further improvedAn amount; for doping of atoms (metal or non-metal atoms), the conductivity of the electrode material can be improved. For example, metal atoms have good conductivity, and by utilizing the property, the conductivity of the tin-based material can be improved by doping the metal atoms, and the rate capability of the electrode material can be improved.
CN104157876A provides a preparation method of a porous carbon-tin nanocomposite for a lithium battery cathode, which is characterized in that crop wastes are carbonized to prepare a porous carbon matrix; dispersing a porous carbon matrix in 0.1-2mol/L tin precursor solution to obtain a porous carbon-tin dioxide composite material; heating and reacting the porous carbon-tin dioxide composite material with a natural polymer solution to obtain a precursor of the carbon-coated nano composite material; and sealing and heating the precursor in a nitrogen environment for reaction to obtain the porous carbon-tin nano composite material.
CN113690425A provides a high-capacity silicon-based composite lithium battery negative electrode material and a preparation method thereof: weighing 30g of silicon monoxide and 60g of tin powder, uniformly mixing, placing in a sand mill, sanding for 10 hours at a speed of 500r/min in an argon atmosphere until the particle size is 10-20 nm, and obtaining a product c; and (3) uniformly mixing the product c with a proper amount of phenolic resin (according to the residual carbon content, ensuring that the carbon content in the finally prepared material is 5%), calcining in a tubular furnace under the argon atmosphere at the heating rate of 5 ℃/min, heating to 550 ℃, preserving heat for 4h, and naturally cooling to obtain the silicon-based composite lithium battery negative electrode material.
Disclosure of Invention
The invention aims to solve the technical problem of providing a tin/carbon nano lithium battery negative electrode material and a preparation method thereof.
In order to solve the technical problem, the invention provides a preparation method of a tin/carbon nano lithium battery negative electrode material, which comprises the following steps:
1) mixing tin acetate (Sn (CH) 3 COO) 2 ) PAN (polyacrylonitrile) at 1: mixing the materials according to the mass ratio of 2 +/-0.1, adding a solvent for dissolving, heating the obtained mixed solution to 60 +/-10 ℃ in a water bath, and stirring the mixed solution for 24 +/-2 hours by using a magnetic stirrer in a heat preservation manner to obtain a spinning solution;
2) adding the spinning solution into a propeller, spinning by using electrostatic spinning equipment, and drying to obtain a tin/carbon nanofiber precursor;
3) carrying out cryogenic treatment on the tin/carbon nanofiber precursor obtained in the step 2) by using liquid nitrogen;
4) and carbonizing the tin/carbon nanofiber precursor subjected to cryogenic treatment in the step 3) to obtain the tin/carbon nano lithium battery cathode material.
As an improvement of the preparation method of the tin/carbon nano lithium battery negative electrode material, the cryogenic treatment in the step 3) is as follows:
placing the precursor of the tin/carbon nanofiber in a deep cooling box with sufficient liquid nitrogen, wherein the temperature control process comprises the following steps: keeping at 20 deg.C for 30min, cooling to-70 deg.C for 45min, maintaining at-70 deg.C for 60min, cooling to-120 deg.C for 20min, cooling to-196 deg.C for 38min from-120 deg.C, maintaining at-196 deg.C for 12h, and deep cooling to room temperature; obtaining the tin/carbon nanofiber precursor after the cryogenic treatment.
That is, the cooling rate is about 2 deg.C/min.
As a further improvement of the preparation method of the tin/carbon nano lithium battery negative electrode material, the carbonization in the step 4) is as follows:
heating the tin/carbon nanofiber precursor subjected to cryogenic treatment to 280 ℃ in air at a heating rate of 2 ℃/min from room temperature, and preserving heat for 7 hours; then heating to 800 ℃ at the speed of 2 ℃/min under the protection of inert gas (such as nitrogen) and preserving heat for 2 h; and finally, cooling to room temperature to obtain the tin/carbon nano lithium battery negative electrode material.
As a further improvement of the preparation method of the tin/carbon nano lithium battery negative electrode material of the invention, in the step 2):
spinning voltage is 16-20 kV, collecting is carried out by adopting a roller with a collecting distance of 18cm, and the spinning advancing speed is 1 mL/h.
As a further improvement of the preparation method of the tin/carbon nano lithium battery negative electrode material of the invention, in the step 1):
the solvent was N, N-Dimethylformamide (DMF).
As a further improvement of the preparation method of the tin/carbon nano lithium battery negative electrode material of the invention, in the step 1): 36. + -.6 g of N, N-Dimethylformamide (DMF) are used per 0.6g of tin acetate.
The invention also provides the tin/carbon nano lithium battery negative electrode material prepared by any method.
The invention uses tin acetate (Sn (CH) 3 COO) 2 ) As an organic precursor, PAN was used as a carbon source to prepare the spinning solution.
In CN113690425A, the tin dioxide is reduced by amorphous carbon in the matrix at high temperature, while the melting point of the reduced product tin is only 232 ℃, and the reduced product tin is easily aggregated in liquid state to form aggregates in high temperature environment, which is not favorable for obtaining the dispersion state of nano-sized tin. The cryogenic treatment method adopted by the invention enables the reduced simple substance tin to be cooled to a solid state before agglomeration and growth, and in the process of gradually returning to the room temperature from the cryogenic state, the internal lattice structure of the material is recrystallized and the crystal grains rotate to form a preferred orientation recrystallization structure, so that the crystallinity of the Sn crystal grains is increased, and the Sn crystal grains are more easily embedded and separated in a carbon-coated porous structure, thereby improving the specific capacity and the cycle efficiency of the tin/carbon nano lithium battery negative electrode material, and enhancing the electrochemical performance.
The invention successfully applies the cryogenic treatment mode to the preparation of the tin/carbon nano lithium battery cathode material and optimizes and discusses the sequence of the cryogenic treatment and the carbonization treatment; as an effective thermal compensation process, the cryogenic treatment has the main advantages of enhancing the strength, toughness and wear resistance of the material, reducing the deformation of the external dimension of the material, improving the uniformity of the microstructure of the material, prolonging the service life of the material and the like. In the cryogenic treatment process, carbide is difficult to diffuse in a low-temperature environment, the diffusion distance is shortened, and in addition, the volume is shrunk, the lattice constant is reduced, so that carbon atoms are separated out; on the other hand, each phase in the fiber generates volume shrinkage, the internal stress of the material is increased due to different shrinkage rates of each phase, the crystal is in a thermodynamically unstable state, and in the process of gradually returning to the room temperature from the cryogenic state, the lattice structure in the material is recrystallized and the crystal grains rotate to form a recrystallization structure with preferred orientation, so that the crystallinity of the Sn crystal grains is increased, the cycle efficiency of the battery is improved, and the active substance is improved.
Therefore, the invention provides a tin/carbon nano lithium battery negative electrode material and a preparation method thereof, aiming at the problems of poor cycle performance and the like caused by the structural collapse and the crushing of the tin-based lithium battery negative electrode material.
In the invention, the tin/carbon nano lithium battery negative electrode material is subjected to performance detection in a conventional mode as follows:
firstly, grinding a tin/carbon nano lithium battery negative electrode material into powder, and then mixing the powder with the following components in a mass ratio of 8: 1:1 respectively weighing electrode active substances (namely Sn/C nanofiber powder), acetylene black and polyvinylidene fluoride (PVDF), adding N-methyl pyrrolidone (NMP) as a binder, mixing to prepare uniform slurry, uniformly coating the uniform slurry on a copper foil, and drying for 9 hours in vacuum at 100T.
And secondly, cutting the smear into a circular sheet with the diameter of 12mm as a battery cathode, taking a lithium sheet as an antipode, and assembling the circular sheet, the electrolyte and the diaphragm into a button cell in a glove box under the protection of argon. And then, performing constant current charge and discharge test on a battery test board, and taking the previous 100 circles of effective data. The test current density is 50mA/g, and the voltage range is 0.02-2.70V.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the invention, the tin/carbon nanofiber is subjected to shape reconstruction by utilizing electrostatic spinning and cryogenic treatment processes, so that the nanofiber with a pore structure and a skin-core structure is manufactured, and the volume expansion and structure collapse of the nanofiber serving as a lithium battery negative electrode material are effectively relieved, so that the capacity loss is inhibited; on the other hand, because the polarization generated by the internal resistance is small, the electrochemical cycling stability of the material is effectively ensured.
(2) The deep cooling treatment enables the lattice structure in the tin/carbon nano-fiber nano-material to be recrystallized and the crystal grains to rotate, so that a recrystallization structure with preferred orientation is formed, the particle agglomeration is effectively inhibited, the specific capacity and the capacity circulation rate are improved, and the electrochemical performance is stabilized.
(3) The invention has simple and safe operation process and obvious effect.
Drawings
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
FIG. 1 is a process diagram of the cryogenic treatment process of the present invention.
FIG. 2 is an XRD spectrum of Sn/C nanofibers- -Sn/C (I), Sn/C (II), Sn/C (III);
description of the invention: JCPDS card is the basis of X-ray qualitative phase analysis; the XRD qualitative phase analysis is a method for comparing the measured diffraction spectrum of an unknown phase with standard data of a known crystal structure phase in a JCPDS card; JCPDS04-0673 represents a standard diffraction peak angle contrast card of Sn.
FIG. 3 shows that the negative electrode material of the tin/carbon nanofiber lithium battery is 1A g -1 Constant current charge-discharge curve under the current density of (1).
In FIG. 3, a, Sn/C (I) charge-discharge curves; b. Sn/C (II) charge-discharge curve; c. Sn/C (III) charge-discharge curve;
1 st represents the first-turn charge-discharge curve, 2 nd Representing the second turn charge-discharge curve.
FIG. 4 is a cyclicity curve of a tin/carbon nanofiber negative electrode material according to the present invention.
Detailed Description
The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto:
example 1, a method of preparing tin/carbon nanofibers, sequentially performing the following steps:
the method comprises the following steps: 0.6g of tin acetate (Sn (CH) is weighed 3 COO) 2 ) And mixing with 1.2g of PAN, adding 36g of N, N-Dimethylformamide (DMF) for dissolving, heating the obtained mixed solution in a water bath at 60 ℃, keeping the temperature, and stirring for 24 hours by using a magnetic stirrer at the stirring speed of 600rpm to obtain a spinning solution.
Step two: and (2) adding the spinning solution obtained in the step one into a propeller, spinning by using electrostatic spinning equipment, wherein the spinning voltage is 18kV, collecting by using a roller with the collection distance of 18cm, and the spinning propelling speed is 1mL/h to obtain the tin/carbon nanofiber precursor.
Step three: carbonizing the tin/carbon nanofiber precursor obtained in the step two in a carbonization furnace, wherein the carbonization process conditions are as follows: heating to 280 ℃ in the air from room temperature at the heating rate of 2 ℃/min, and keeping the temperature for 7 h; then heating to 800 ℃ at the speed of 2 ℃/min under the protection of nitrogen and preserving heat for 2 h; finally naturally cooling to room temperature; the tin/carbon nanofibers are obtained and are marked as Sn/C (I).
The XRD pattern of the Sn/C nanofiber (Sn/C (I)) is shown in Sn/C (I) of FIG. 2, which is consistent with 100% of the cubic system in the standard sample card JCPDS04-0673 of metallic Sn, and shows that Sn with high crystallinity exists in the Sn/C (I) sample. The constant current charge-discharge experiment of 1Ag & 1 in figure 3 shows that the specific capacities of the charge and discharge mass of the first ring of the Sn/C (I) nano fiber are 252.9 and 583.7mA & h/g respectively, and the coulombic efficiency is 43.3 percent; in the cycle performance curve of FIG. 4, the specific mass capacity of the Sn/C (I) nanofibers decreases to 343.3mA-h/g after 100 cycles, the specific mass capacity retention rate is 80%, and the cycle performance is unstable.
Description of the drawings: assuming that the amount of PAN used was changed from 1.2g to 0.6g, i.e., tin acetate: the mass ratio of PAN is 1: 1; it can result in a solution that is too viscous to be spun.
Example 2, a method for preparing a tin/carbon nano lithium battery negative electrode material sequentially includes the following steps:
the steps one to two are the same as in example 1.
Step three: and D, carrying out cryogenic treatment on the tin/carbon nanofiber precursor obtained in the step two, and specifically comprising the following steps:
placing the precursor of the tin/carbon nanofiber obtained in the step two in a deep cooling box with sufficient liquid nitrogen, wherein the cooling rate of the deep cooling box is about 2 ℃/min, and the temperature control process is as follows: maintaining at 20 deg.C for 30min, cooling to-70 deg.C for 45min, maintaining at-70 deg.C for 60min, cooling to-120 deg.C for 20min, cooling to-196 deg.C for 38min from-120 deg.C, maintaining at-196 deg.C for 12h, and naturally recovering to room temperature;
step four: the method is equivalent to the third step of the embodiment 1, namely specifically comprises the following steps: carbonizing the tin/carbon nanofiber precursor subjected to cryogenic treatment obtained by the third treatment in a carbonization furnace, wherein the carbonization process conditions are as follows: heating to 280 ℃ in the air from room temperature at the heating rate of 2 ℃/min, and keeping the temperature for 7 h; then heating to 800 ℃ at the speed of 2 ℃/min under the protection of nitrogen and preserving heat for 2 h; and finally naturally cooling to room temperature to obtain the tin/carbon nano lithium battery negative electrode material marked as Sn/C (II).
The XRD pattern of Sn/C (II) as shown in the figure 2Sn/C (II) and Sn/C (I) in the Sn/C (II) sample shows that Sn with high crystallinity exists, but the diffraction peak intensity of the Sn/C (II) sample is increased, and due to the fact that volume shrinkage of each phase in the fiber is generated in the low-temperature treatment process, internal stress of the material is increased due to different shrinkage rates of each phase, crystals generate defects, and the material is in a thermodynamically unstable state. In the process of returning to the room temperature from the cryogenic state, randomly oriented Sn crystal grains are preferentially oriented to favorable positions, and the crystallinity of tin is increased, so that the diffraction peak of the Sn is enhanced. In the figure 3, the charge-discharge mass specific capacity of the first circle of the Sn/C (II) nanofiber is 255.3 and 631.9 mA.h/g respectively, the coulomb efficiency is 40.4 percent, and the charge-discharge mass specific capacity of the first circle of the Sn/C (I) nanofiber is improved. FIG. 4 shows a cycle performance curve that the Sn/C (II) fiber shows the best cycle stability, the specific mass capacity is 402.3mA · h/g after 50 cycles, the specific mass capacity is 401.4mA · h/g after 100 cycles, and the specific mass capacity retention rate is 93.9%; such a large specific capacitance indicates that the resulting material has excellent lithium electrical properties.
The advantages of Sn/C (II) over Sn/C (I) are: the Sn/C (II) sample is subjected to cryogenic treatment, so that crystal grains in the fiber are rearranged, and the excellent lithium battery cycle performance is shown: on the one hand, the porous structure due to the fibers can effectively alleviate the volume expansion and thus inhibit the capacity loss; on the other hand, because the polarization generated by the internal resistance is small, the electrochemical cycling stability of the material is effectively ensured.
Example 3, a method for preparing a tin/carbon nano lithium battery negative electrode material sequentially includes the following steps:
the same procedures as in example 1 were repeated for the first to third steps.
Step four: performing cryogenic treatment on the Sn/C (I) obtained in the step three, wherein the process parameters of the cryogenic treatment are equal to those of the embodiment 2, namely the method specifically comprises the following steps:
placing Sn/C (I) in a cryogenic refrigerator with sufficient liquid nitrogen for low-temperature treatment, wherein the temperature control process comprises the following steps: maintaining at 20 deg.C for 30min, cooling to-70 deg.C for 45min, maintaining at-70 deg.C for 60min, cooling to-120 deg.C for 20min, cooling to-196 deg.C for 38min from-120 deg.C, maintaining at-196 deg.C for 12h, ending the process, and naturally returning to room temperature; obtaining the tin/carbon nano lithium battery cathode material which is marked as Sn/C (III).
An XRD (X-ray diffraction) pattern of Sn/C (III) which is a tin/carbon nano lithium battery negative electrode material is shown in figure 2Sn/C (III), and Sn with high crystallinity exists like Sn/C (I) and Sn/C (II), a diffraction peak is strongest, and the diffraction peak is strengthened due to the preferential orientation of irregular Sn crystal grains in the low-temperature treatment process.
In the figure 3, the charge-discharge mass specific capacities of the first circle of the Sn/C (III) nano-fiber are respectively 190.4 and 545.8 mA.h/g of the charge-discharge mass specific capacity of the first circle, and the coulomb efficiency is 34.8%. Fig. 4 shows the cycle performance curve, the specific mass capacity after 100 cycles is 445.1mA · h/g, the specific mass capacity retention rate is 83.5%, and although the fiber has higher specific mass capacity, the cycle performance is extremely unstable compared with Sn/c (ii) nanofiber, and the specific mass capacity is in a descending trend from 30 cycles.
When the results of examples 1 to 3 were compared, it was found that:
compared with other 2 samples, the Sn/C (II) nanofiber subjected to cryogenic treatment and carbonization sequentially shows high mass specific capacity and excellent cycling stability, mainly because the randomly oriented Sn crystal grains are preferentially oriented to a favorable position, the crystallinity of Sn is increased, active substances are enhanced, and meanwhile, the unique porous structure of the nanofiber effectively relieves volume expansion in the charging and discharging processes and shortens ion transmission distance. The carbon coating structure effectively prevents Sn from being separated from C, and ensures the cycling stability of the electrode material.
In summary, example 2 is the best case, while example 3 is performed by first performing carbonization treatment and then performing cryogenic treatment, so that the Sn/C nanofibers precipitate a carbon layer, which results in a more compact internal structure of the carbon layer, which is not favorable for metal dispersion, which cannot effectively buffer the volume expansion during charge and discharge, and makes the intercalation and deintercalation of lithium ions inside more difficult, which results in capacity attenuation, and the cycle stability is not as good as that of example 2, which is in a decreasing trend.
Comparative example 1, the weight of the organic precursor changed from tin acetate to tin tetrachloride salt remained unchanged and was still 0.6g, and the rest was the same as example 2.
The results obtained were respectively:
when tin tetrachloride is used as tin salt, the charge-discharge capacity of the first circle is 203.5mAh/g, 667.6mAh/g, the first coulombic efficiency is 30.5%, and the discharge capacity after 60 cycles is 536.4mAh g -1 However, after 100 cycles, the decrease was 235.7mAh · g -1 . The XRD results showed that the crystal structure of the material after 30 times of charge and discharge was not greatly affected, but the crystal structure began to be destroyed from 60 cycles, the specific mass capacity began to decrease, and the cycle stability was deteriorated. It is clear that tin tetrachloride as a tin salt exhibits its electrochemical properties extremely unstably, and does not behave as much as tin acetate as a tin salt as a whole.
Comparative example 2, the carbon source was changed from PAN to glucose, the weight remained unchanged, still 1.2g, and the rest was identical to example 2.
The results obtained were: when glucose is used as a carbon source, the first circle of charge-discharge capacity is 324.6Ah/g and 438mAh/g, the discharge capacity after 50 times of circulation is 360mAh/g, the discharge capacity after 100 circles is 288.4mAh/g, and the specific mass capacity always shows a descending trend and is unstable.
Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.
Claims (7)
1. The preparation method of the tin/carbon nano lithium battery negative electrode material is characterized by comprising the following steps of:
1) mixing tin acetate and PAN in a ratio of 1: mixing the materials according to the mass ratio of 2 +/-0.1, adding a solvent for dissolving, heating the obtained mixed solution to 60 +/-10 ℃ in a water bath, and stirring the mixed solution for 24 +/-2 hours by using a magnetic stirrer in a heat preservation manner to obtain a spinning solution;
2) adding the spinning solution into a propeller, spinning by using electrostatic spinning equipment, and drying to obtain a tin/carbon nanofiber precursor;
3) carrying out cryogenic treatment on the tin/carbon nanofiber precursor obtained in the step 2) by using liquid nitrogen;
4) and carbonizing the subzero treated tin/carbon nanofiber precursor obtained in the step 3) to obtain the tin/carbon nano lithium battery negative electrode material.
2. The preparation method of the tin/carbon nano lithium battery anode material according to claim 1, wherein the cryogenic treatment in the step 3) is:
placing the precursor of the tin/carbon nanofiber in a deep cooling box with sufficient liquid nitrogen, wherein the temperature control process comprises the following steps: maintaining at 20 deg.C for 30min, cooling to-70 deg.C for 45min, maintaining at-70 deg.C for 60min, cooling to-120 deg.C for 20min, cooling to-196 deg.C for 38min from-120 deg.C, maintaining at-196 deg.C for 12h, and performing cryogenic treatment to recover to room temperature; obtaining the tin/carbon nanofiber precursor after the cryogenic treatment.
3. The preparation method of the tin/carbon nano lithium battery negative electrode material according to claim 2, wherein the carbonization in the step 4) is as follows:
heating the tin/carbon nanofiber precursor subjected to cryogenic treatment to 280 ℃ in air at a heating rate of 2 ℃/min from room temperature, and preserving heat for 7 hours; then heating to 800 ℃ at the speed of 2 ℃/min under the protection of inert gas and preserving heat for 2 h; and finally, cooling to room temperature to obtain the tin/carbon nano lithium battery negative electrode material.
4. The method for preparing the tin/carbon nano lithium battery anode material according to claim 3, wherein in the step 2):
spinning voltage is 16-20 kV, collecting is carried out by adopting a roller with a collecting distance of 18cm, and the spinning advancing speed is 1 mL/h.
5. The preparation method of the tin/carbon nano lithium battery anode material according to any one of claims 1 to 4, characterized in that in the step 1):
the solvent is N, N-dimethylformamide.
6. The method for preparing the tin/carbon nano lithium battery anode material according to claim 5, wherein in the step 1): 36 plus or minus 6g of N, N-dimethylformamide is used for every 0.6g of tin acetate.
7. The tin/carbon nano lithium battery negative electrode material prepared by the method of any one of claims 1 to 6.
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