CN116031374A - Antimony-based alloy negative electrode material, preparation method thereof, negative electrode plate and lithium ion battery - Google Patents

Abstract

The application relates to the field of lithium ion batteries and discloses CoFe ₃ Sb ₁₂ Alloy anode material, preparation method thereof, anode piece and lithium ion battery. The negative electrode material comprises CoFe ₃ Sb ₁₂ An alloy, a graphitized carbon coating layer and an amorphous carbon coating layer; the graphitized carbon coating layer coats one or more CoFe ₃ Sb ₁₂ Alloy particles, the amorphous carbon coating layer coating the graphitized carbon coating layer. The application selects proper graphitized carbon material to coat the CoFe by a vapor deposition method ₃ Sb ₁₂ The surface is coated by amorphous carbon, and the formed double-layer coating structure effectively prevents CoFe ₃ Sb ₁₂ The cracking of the alloy improves the cycle performance, the multiplying power performance, the first charge and discharge performance and the like of the alloy, and further improves the capacity and the electric conductivity of the alloy.

Description

Antimony-based alloy negative electrode material, preparation method thereof, negative electrode plate and lithium ion battery

Technical Field

The application relates to the field of lithium ion batteries, in particular to CoFe ₃ Sb ₁₂ Alloy anode material, preparation method thereof, anode piece and lithium ion battery.

Background

The lithium ion battery has the advantages of high voltage, high energy density, good safety performance and the like, and is wide in application range, and researches on negative electrode materials of the lithium ion battery are more and more active. Graphite and various carbon anode materials using graphite as a precursor have the defects of large energy loss, poor high-rate charge-discharge performance and the like, and the electrochemical mechanism of the multiphase compound of tin is that lithium ions and tin react reversibly to form Li _x Sn, which enables lithium ions to be reversibly extracted and intercalated in the electrode; similar CoFe ₃ Sb ₁₂ The alloy has high capacity and good conductivity, and can be used as a better anode material.

Although CoFe ₃ Sb ₁₂ The alloy has the advantages of high capacity, good conductivity and the like when used as a cathode material, but lithium ions are in alloy CoFe ₃ Sb ₁₂ Embedding and coating the negative electrode materialDendrite is formed during deintercalation, alloy molecules are oxidized and cracked to form a passivation film, and the cycle performance, the multiplying power performance, the electric conductivity and the like are affected.

Disclosure of Invention

In view of the above, it is an object of the present application to provide a CoFe ₃ Sb ₁₂ The alloy anode material and the preparation method thereof enable the anode material to improve the cycle performance, the multiplying power performance, the first charge-discharge performance and the electric conduction performance;

another object of the present application is to provide a negative electrode tab and a lithium ion battery based on the above negative electrode material.

To solve or at least partially solve the above technical problems, as a first aspect of the present application, there is provided a CoFe ₃ Sb ₁₂ Alloy negative electrode material including CoFe ₃ Sb ₁₂ An alloy, a graphitized carbon coating layer and an amorphous carbon coating layer; the graphitized carbon coating layer coats one or more CoFe ₃ Sb ₁₂ Alloy particles, the amorphous carbon coating layer coating the graphitized carbon coating layer.

Optionally, the CoFe ₃ Sb ₁₂ The mass percentage of the alloy is 90-99%, and the mass percentage of the graphitized carbon coating layer and the amorphous carbon coating layer is 1-10%.

Optionally, the graphitized carbon coating layer includes graphitized carbon material including one or more of Mesophase Carbon Microspheres (MCMB), carbon fibers, and carbon nanotubes.

Optionally, the amorphous carbon coating comprises an amorphous carbon material formed from a carbon source; further alternatively, the carbon source comprises a gaseous carbon source and/or a solid carbon source, wherein the gaseous carbon source comprises C ₁ -C ₄ Alkane, C ₂ -C ₄ Olefins, C ₂ -C ₄ One or two or more alkynes of (a) are provided.

Optionally, the gaseous carbon source further comprises a borane or a phosphane.

As a second aspect of the present application, there is provided a method for producing the anode material, comprising:

by CoFe ₃ Sb ₁₂ Atomic vapor deposition is carried out by taking the alloy as a matrix and graphitized carbon material as a target material to obtain graphitized carbon coated CoFe ₃ Sb ₁₂ A composite material;

coating the graphitized carbon with CoFe in a carbon source environment ₃ Sb ₁₂ And carbonizing the composite material at high temperature to form an amorphous carbon coating layer to obtain the anode material.

As a third aspect of the present application, there is provided a negative electrode tab having the negative electrode material described herein as an active material.

As a fourth aspect of the present application, there is provided a lithium ion battery comprising a positive electrode sheet, a separator, an electrolyte, and a negative electrode sheet as described herein.

With conventional CoFe ₃ Sb ₁₂ Compared with the anode materials such as alloy, the method selects proper graphitized carbon materials to coat the CoFe by a vapor deposition method ₃ Sb ₁₂ The surface is coated by amorphous carbon, and the formed double-layer coating structure effectively prevents CoFe ₃ Sb ₁₂ The cracking of the alloy improves the cycle performance, the multiplying power performance, the first charge and discharge performance and the like of the alloy, and further improves the capacity and the electric conductivity of the alloy.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute an undue limitation to the application;

fig. 1 is a schematic structural diagram of a negative electrode material according to the present application;

fig. 2 is an SEM image of the anode material described in the present application.

Detailed Description

The application discloses a CoFe ₃ Sb ₁₂ Alloy anode material, preparation method thereof, anode piece and lithium ion battery, and those skilled in the art can properly improve the technological parameters by referring to the content of the present disclosure. It is particularly pointed out that all classesSimilar substitutions and modifications will readily occur to those skilled in the art, and are intended to be included in the present application. The products, processes and applications described herein have been described in terms of preferred embodiments, and it will be apparent to those skilled in the relevant art that variations and suitable modifications and combinations of the methods described herein can be made to practice and use the technology of the present application without departing from the spirit and scope of the present application. It will be apparent that the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.

It should be noted that, in this document, relational terms such as "first" and "second," "step 1" and "step 2," and "(1)" and "(2)" and the like, if any, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Meanwhile, the embodiments and features in the embodiments in the present application may be combined with each other without conflict.

In a first aspect of the present application, there is provided a CoFe ₃ Sb ₁₂ Alloy negative electrode material including CoFe ₃ Sb ₁₂ An alloy, a graphitized carbon coating layer and an amorphous carbon coating layer; the graphitized carbon coating layer coats one or more CoFe ₃ Sb ₁₂ Alloy particles, the amorphous carbon coating layer coating the graphitized carbon coating layerThe method comprises the steps of carrying out a first treatment on the surface of the In other embodiments of the present application, the negative electrode material has a granular structure, uniform size distribution, and particle size of 1-5 μm, and the structure is schematically shown in fig. 1 and the SEM is shown in fig. 2.

In certain embodiments of the present application, the CoFe ₃ Sb ₁₂ The mass percentage of the alloy is 90-99%, and can be 94-97%, such as 94.1%, 95.1%, 96.1%, etc., and the mass percentage of the graphitized carbon coating layer and the amorphous carbon coating layer is 1-10%, and can be 3-6%, such as 3.9%, 4.9%, 5.9%, etc.; in other embodiments of the present application, the amorphous carbon coating layer: graphitized carbon coating mass ratio = 1: (1-2), e.g., 1:1, 1:1.5, 1:2, etc.

In certain embodiments of the present application, the graphitized carbon coating layer comprises graphitized carbon material comprising one or more of mesophase carbon microspheres, carbon fibers, and carbon nanotubes.

In certain embodiments of the present application, the amorphous carbon coating comprises an amorphous carbon material formed from a carbon source; in other embodiments of the present application, the carbon source comprises a gaseous carbon source and/or a solid carbon source; in other embodiments of the present application, wherein the gaseous carbon source comprises C ₁ -C ₄ Alkane, C ₂ -C ₄ Olefins, C ₂ -C ₄ One or two or more alkynes of (a) such as methane, ethane, acetylene, etc.; in other embodiments of the present application, the gaseous carbon source further comprises a borane or a phosphane, e.g., B ₂ H ₆ Or pH of ₃ The method comprises the steps of carrying out a first treatment on the surface of the The volume ratio of the carbon source in the gas carbon source to the borane or the phosphane is 10:1-5, and can be specifically selected from 10:1, 10:2, 10:3, 10:4 or 10:5.

In a second aspect of the present application, there is provided a method for preparing the anode material, including:

by CoFe ₃ Sb ₁₂ Atomic vapor deposition is carried out by taking the alloy as a matrix and graphitized carbon material as a target material to obtain graphitized carbon coated CoFe ₃ Sb ₁₂ An alloy material;

at carbonCoFe coating the graphitized carbon in a source environment ₃ Sb ₁₂ And (3) carbonizing the alloy material at high temperature to form an amorphous carbon coating layer to obtain the anode material.

In certain embodiments of the present application, less than 5 parts by weight of graphitized carbon material and up to 100 parts by weight of CoFe ₃ Sb ₁₂ Carrying out atomic vapor deposition on the alloy; in other embodiments of the present application, 2, 3, or 4 parts by weight of graphitized carbon material and 98, 97, or 96 parts by weight of CoFe ₃ Sb ₁₂ The alloy is subjected to atomic vapor deposition.

In certain embodiments of the present application, the atomic vapor deposition procedure may be referenced as follows:

(1) introducing graphitized carbon material;

(2) purging with inert gas;

(3) introducing an oxygen source;

(4) purging with inert gas;

(5) introducing water;

(6) purging with inert gas;

(7) cycling from step (1) until the demand is reached;

wherein, the time and the cycle number required by each stage program are determined according to the actual requirement, for example, 10-100 cycles are circulated; the inert gas may be selected from nitrogen, argon, and the like;

in other embodiments of the present application, the atomic vapor deposition process may be referenced as follows:

(1) introducing graphitized carbon material for 1s;

(2) nitrogen purging for 60s;

(3) introducing an oxygen source for 5s;

(4) nitrogen purging for 5s;

(5) introducing water for 0.05s;

(6) nitrogen purge for 50s;

(7) cycling 10-100 times from step (1).

In some embodiments of the present application, the carbon source environment is selected to use a gaseous carbon source atmosphere, and may specifically include C ₁ -C ₄ Alkane, C ₂ -C ₄ Olefins, C ₂ -C ₄ One or two or more alkynes of (a) such as methane, ethane, acetylene, etc.; in other embodiments of the present application, the gaseous carbon source further comprises a borane or a phosphane, e.g., B ₂ H ₆ Or pH of ₃ The method comprises the steps of carrying out a first treatment on the surface of the The volume ratio of the carbon source in the gas carbon source to the borane or the phosphane is 10:1-5, and can be specifically selected from 10:1, 10:2, 10:3, 10:4 or 10:5. In other embodiments of the present application, the gaseous carbon source has a ventilation of 100 to 500mL/min.

In certain embodiments of the present application, the high temperature carbonization is a heat preservation treatment at 800-1200 ℃ for 1-6 hours; in other embodiments of the present application, the high temperature carbonization is performed at a temperature increase rate of 1-10 ℃/min to 800-1200 ℃ and then is performed for 1-6 hours.

In certain embodiments of the present application, there is provided a process for preparing the anode material, comprising:

s1: graphitized carbon material and CoFe ₃ Sb ₁₂ The alloys are respectively ball-milled by CoFe ₃ Sb ₁₂ As a substrate, graphitized carbon material as a target, atomic vapor deposition was performed according to the following procedure:

(1) graphitizing the carbon material for 1 second; (2) nitrogen purge for 60 seconds; (3) introducing an oxygen source for 5 seconds; (4) nitrogen purge for 5 seconds; (5) introducing water for 0.05 seconds; (6) nitrogen purge for 50 seconds; (7) cycling 10-100 turns from step (1);

in CoFe ₃ Sb ₁₂ Depositing graphitized carbon material on the substrate to obtain graphitized carbon coated CoFe ₃ Sb ₁₂ A composite material;

s2: coating graphitized carbon with CoFe ₃ Sb ₁₂ Transferring into a carbon source gas atmosphere, heating to 800-1200 ℃ at a heating rate of 1-10 ℃/min and preserving heat for 1-6h to obtain the amorphous carbon/graphitized carbon coated CoFe ₃ Sb ₁₂ Alloy negative electrode material.

In a third aspect of the present application, there is provided a negative electrode tab having the negative electrode material described herein as an active material.

In certain embodiments of the present application, the negative electrode tab includes a current collector and an active material coated on the current collector; wherein the current collector may be selected from a metal foil having good electrical conductivity, such as copper foil or aluminum foil; the active material includes the negative electrode material described herein, and a binder, a conductive agent, and a solvent, which are conventionally selected, and the amount thereof and the like, without being particularly limited thereto.

In a fourth aspect of the present application, there is provided a lithium ion battery comprising a positive electrode sheet, a separator, an electrolyte, and a negative electrode sheet as described herein; in certain embodiments of the present application, the lithium ion battery is a pouch battery or a button battery.

In certain embodiments of the present application, the positive electrode sheet comprises a ternary material as an active material, e.g., liNi _{1/ 3} Co _1/3 Mn _1/3 O ₂ The method comprises the steps of carrying out a first treatment on the surface of the The membrane adopts a cellgard series membrane, such as cellgard 2400 and the like; the electrolyte is LiPF ₆ The solution is electrolyte, for example, ethylene Carbonate (EC) and diethyl carbonate (DEC) with volume ratio of 1:1 are used as solvents, and LiPF ₆ Electrolyte with concentration of 1.0-1.5 mol/L.

In each of the comparative experiments provided herein, unless specifically indicated otherwise, other experimental conditions, materials, etc. were consistent for comparison, except for the differences noted in each group. In addition, the materials used in the present application are all commercially available.

The following provides a CoFe ₃ Sb ₁₂ Alloy cathode material, preparation method thereof and cathode piece and lithium ion battery are further described.

Example 1:

s1: 3g of Mesophase Carbon Microsphere (MCMB) material was placed in a ball mill and ball milled at 300 rpm for 1 hour, 97g CoFe ₃ Sb ₁₂ Ball milling at 1000 rpm for 2 hr, and atomic vapor deposition to obtain CoFe ₃ Sb ₁₂ Transferring into a vacuum cavity and taking the substrate as a target, wherein MCMB is taken as a target material according to the following parameters ((1) MCMB material 1 second, (2) nitrogen purging 60 seconds, (3) oxygen source 5 seconds, (4) nitrogen purging 5 seconds, (5) water filling 0.05 seconds, (6) nitrogen purging 50 seconds, and (7) from the steps(1) Start cycle 60 turns) at its CoFe ₃ Sb ₁₂ Depositing MCMB on the substrate to obtain MCMB coated CoFe ₃ Sb ₁₂ A composite material;

s2: coating MCMB with CoFe ₃ Sb ₁₂ Transferring into a tube furnace, introducing xenon inert gas to remove air in the tube, and introducing methane mixed gas (volume ratio, methane: PH) ₃ =10:4, flow 300 ml/min), and heating to 1000 ℃ at a heating rate of 10 ℃/min and keeping the temperature for 2 hours to obtain amorphous carbon/MCMB coated CoFe ₃ Sb ₁₂ Alloy negative electrode material (amorphous carbon coating layer: MCMB coating layer: coFe) ₃ Sb ₁₂ Alloy = 1:1.5:48.5).

Example 2:

s1: 4g of carbon fiber material is put into a ball mill for ball milling for 1 hour at 400 r/min, 96g of CoFe ₃ Sb ₁₂ Ball milling at 900 rpm for 2.5 hr, and atomic vapor deposition to obtain CoFe ₃ Sb ₁₂ Transferring into a vacuum cavity and taking the carbon fiber as a matrix, taking the carbon fiber as a target material, and taking the carbon fiber material as a target material according to the following parameters ((1) carbon fiber material for 1 second, (2) nitrogen purging for 60 seconds, (3) oxygen source introduction for 5 seconds, (4) nitrogen purging for 5 seconds, (5) water introduction for 0.05 seconds, (6) nitrogen purging for 50 seconds, (7) circulating 80 circles from the step (1) in the CoFe of the carbon fiber material ₃ Sb ₁₂ Depositing carbon fiber on the matrix to obtain carbon fiber coated CoFe ₃ Sb ₁₂ A composite material;

s2: coating carbon fiber with CoFe ₃ Sb ₁₂ Transferring into a tube furnace, introducing argon inert gas to remove air in the tube, and introducing ethane mixed gas (volume ratio, ethane: B) ₂ H ₆ =10:2, flow 200 ml/min), and heating to 800 ℃ at a heating rate of 7 ℃/min and preserving heat for 3 hours to obtain amorphous carbon/carbon fiber coated CoFe ₃ Sb ₁₂ Alloy negative electrode material (amorphous carbon coating layer: carbon fiber coating layer: coFe) ₃ Sb ₁₂ Alloy = 1:2:48).

Example 3:

s1: 2g of carbon nanotubes were placed in a ball mill and ball-milled at 500 rpm for 1.5 hours, 98g of CoFe ₃ Sb ₁₂ Ball milling at 1100 rpm for 1.5 hr, and atomic vapor deposition to obtain CoFe ₃ Sb ₁₂ Transferring into a vacuum cavity and taking the carbon nano tube as a matrix, taking the carbon nano tube as a target material, and taking the carbon nano tube material as the target material according to the following parameters ((1) carbon nano tube material for 1 second, (2) nitrogen purging for 60 seconds, (3) oxygen source introduction for 5 seconds, (4) nitrogen purging for 5 seconds, (5) water introduction for 0.05 seconds, (6) nitrogen purging for 50 seconds, (7) circulation for 55 circles from the step (1) in the CoFe process ₃ Sb ₁₂ Depositing carbon nano tube on the substrate to obtain the carbon nano tube coated CoFe ₃ Sb ₁₂ A composite material;

s2: coating CoFe on carbon nano tube ₃ Sb ₁₂ Transferring into a tube furnace, introducing helium inert gas to remove air in the tube, and introducing acetylene mixed gas (volume ratio, acetylene: PH) ₃ =10:4, flow 200 ml/min), and heating to 800 ℃ at a heating rate of 8 ℃/min and keeping the temperature for 2.5h to obtain amorphous carbon/carbon nanotube coated CoFe ₃ Sb ₁₂ Alloy cathode material (amorphous carbon coating layer: carbon nanotube coating layer: coFe) ₃ Sb ₁₂ Alloy = 1:1:49).

Comparative example 1:

CoFe after ball milling in S1 of example 1 ₃ Sb ₁₂ Transferring into a tube furnace, introducing xenon inert gas to remove air in the tube, and introducing methane mixed gas (volume ratio, methane: PH) ₃ =10:4, flow 300 ml/min), and at a heating rate of 10 ℃/min to 1000 ℃ and incubation for 2h, yielding amorphous carbon coated CoFe only ₃ Sb ₁₂ Alloy negative electrode material.

Comparative example 2:

s1: 3g of artificial graphite material was placed in a ball mill and ball-milled at 300 rpm for 1 hour, 97g of CoFe ₃ Sb ₁₂ Ball milling at 1000 rpm for 2 hr, and atomic vapor deposition to obtain CoFe ₃ Sb ₁₂ Transferring into a vacuum cavity and taking the artificial graphite as a matrix, taking the artificial graphite as a target material, and taking the artificial graphite as the target material according to the following parameters ((1) the artificial graphite material for 1 second, (2) the nitrogen purging for 60 seconds, (3) the oxygen source for 5 seconds, (4) the nitrogen purging for 5 seconds, (5) the water for 0.05 seconds, (6) the nitrogen purging for 50 seconds, (7) the cycle for 60 circles from the step (1) to the CoFe of the artificial graphite material) ₃ Sb ₁₂ Depositing artificial graphite on the substrate to obtain artificial graphite coated CoFe ₃ Sb ₁₂ A composite material;

s2: coating artificial graphite with CoFe ₃ Sb ₁₂ Transferring into a tube furnace, introducing xenon inert gas to remove air in the tube, and introducing methane mixed gas (volume ratio, methane: PH) ₃ =10:4, flow 300 ml/min), and heating to 1000 ℃ at a heating rate of 10 ℃/min and keeping the temperature for 2 hours to obtain amorphous carbon/artificial graphite coated CoFe ₃ Sb ₁₂ Alloy negative electrode material (amorphous carbon coating layer: artificial graphite coating layer: coFe) ₃ Sb ₁₂ Alloy = 1:1.5:48.5).

Comparative example 3:

s1: placing 3g of Mesophase Carbon Microsphere (MCMB) material into a ball mill, ball milling for 1 hour at 300 revolutions per minute, transferring 97g of silicon nanoparticles into a vacuum cavity and taking the silicon nanoparticles as a matrix by adopting an atomic vapor deposition method, and taking the MCMB as a target material, wherein the MCMB coated silicon nanoparticle composite material is obtained by placing the MCMB material into the ball mill for ball milling for 1 hour at 300 revolutions per minute, wherein the MCMB material is prepared according to the following parameters ((1) MCMB material for 1 second, (2) nitrogen purging for 60 seconds, (3) oxygen source for 5 seconds, (4) nitrogen purging for 5 seconds, (5) water for 0.05 seconds, (6) nitrogen purging for 50 seconds and (7) circulating for 60 circles from the step (1);

s2: transferring MCMB coated silicon nano particles into a tube furnace, introducing xenon inert gas to remove air in the tube, and then introducing methane mixed gas (volume ratio, methane: PH) ₃ =10:4, flow 300 ml/min), and heating to 1000 ℃ at a heating rate of 10 ℃/min and preserving heat for 2 hours, thus obtaining the amorphous carbon/MCMB coated silicon nanoparticle anode material.

Comparative example 4:

coating the MCMB prepared in S1 of example 1 with CoFe ₃ Sb ₁₂ The composite material is directly used as a negative electrode material.

Experimental example 1:

1.1 SEM test

The alloy anode material prepared in example 1 was subjected to SEM test, and the test results are shown in fig. 2. As can be seen from the figure, the alloy anode material has a granular structure, the size distribution is uniform, and the grain diameter is between (1 and 5) mu m.

1.2, powder physical and chemical Property test

Tap density, specific surface area, and specific capacity were measured for each of the anode materials prepared in examples 1 to 3 and comparative examples 1 to 4. According to GB/T24533-2019, lithium ion battery graphite anode materials. The test results are shown in Table 1.

Table 1 physicochemical properties of negative electrode materials in examples and comparative examples

Project	Conductivity (S/cm)	Tap density (g/cm) 3 )	Specific surface area (m) 2 /g)
				Example 1	20.64	2.87	1.91
Example 2	20.36	2.84	1.84
				Example 3	20.22	2.81	1.82
Comparative example 1	19.53	2.74	1.23
				Comparative example 2	19.42	2.76	1.47
Comparative example 3	19.88	1.84	2.14
				Comparative example 4	19.31	2.83	1.85

As can be seen from Table 1, the electrical conductivity and tap density of the alloy anode materials prepared in examples 1-3 of the present application are slightly improved as compared with the comparative examples. The two layers of coating materials have little influence on the conductivity, and the density of the two layers of coating materials is quite different from that of the alloy, so that the influence on the tap density is quite small, and the graphitized carbon material shows corresponding improvement on the alloy cathode material, so that the tap density of the graphitized carbon material is equivalent to that of the application as shown in comparative example 4; whereas the difference in tap density from the other groups of comparative example 3 is likely due to the difference in silicon density being smaller than the alloy density.

1.3 first charge and discharge Performance test

The negative electrode materials in examples 1 to 3 and comparative examples 1 to 4 were assembled into button cells, respectively. The assembly method comprises the following steps: and adding a binder, a conductive agent and a solvent (the groups are kept consistent) into the cathode material, stirring and pulping, coating the cathode material on a copper foil, and drying and rolling the cathode material to obtain the cathode sheet. The button cell was assembled in a glove box charged with hydrogen, and the electrochemical performance test was performed on a wuhan blue CT2001A type cell tester with a charge-discharge voltage ranging from 0.005V to 2.0V and a charge-discharge rate of 0.1C. The test results are shown in Table 2.

Table 2 comparison of the first charge and discharge properties of examples and comparative examples

As can be seen from table 2, the first discharge capacity and the first charge-discharge efficiency of the lithium ion battery using the anode materials obtained in examples 1-3 are significantly higher than those of the comparative example, and the double coating of amorphous carbon and graphitized carbon can reduce the generation of side reactions for the intercalation and deintercalation of lithium ions in the composite material, prevent the oxidation of alloy particles, reduce irreversible capacity and improve the first efficiency.

1.4 cycle performance and rate performance test

Negative electrode sheets were prepared with the negative electrode materials in examples 1 to 3 and comparative examples 1 to 4. With ternary material (LiNi _{1/ 3} Co _1/3 Mn _1/3 O ₂ ) As positive electrode, with LiPF ₆ Solution (EC+DEC solvent, volume ratio 1:1, liPF) ₆ Concentration of 1.3 mol/L) was used as an electrolyte and cellgard 2400 was used as a separator to prepare a 5Ah pouch cell. And then testing the cycle performance and the multiplying power performance of the soft package battery.

Cycle performance test conditions: the charge-discharge current is 1C/1C, the voltage range is 2.8-4.2V, the cycle number is 500, and the test result is shown in Table 3.

Rate performance test conditions: charging rate: 1C/3C/5C/8C, discharge multiplying power 1C; voltage range: 2.8-4.2V, and the test results are shown in Table 4.

Table 3 comparison of the cycle performance of examples and comparative examples

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As can be seen from Table 3, the cycling performance of the soft-packed battery prepared from the alloy negative electrode material is superior to that of the comparative example, because the double coating of the outer layer of the alloy negative electrode material can enable the negative electrode material to form a stable structure in terms of 1C/1C multiplying power cycling performance, thereby reducing dendrite formation during lithium ion intercalation and deintercalation, and reducing impedance and improving the cycling performance.

Table 4 comparison of the rate performance of examples and comparative examples

As can be seen from table 4, the soft pack batteries prepared from the alloy anode materials of examples 1 to 3 of the present application have better constant current ratio, i.e., the charging time of the soft pack batteries of examples 1 to 3 is better.

The foregoing is merely a specific embodiment of the application to enable one skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. CoFe (CoFe) ₃ Sb ₁₂ An alloy negative electrode material characterized by comprising CoFe ₃ Sb ₁₂ An alloy, a graphitized carbon coating layer and an amorphous carbon coating layer; the graphitized carbon coating layer coats one or more CoFe ₃ Sb ₁₂ Alloy particles, the amorphous carbon coating layer coating the graphitized carbon coating layer.

2. The anode material according to claim 1, wherein the CoFe ₃ Sb ₁₂ The mass percentage of the alloy is 90-99%, and the mass percentage of the graphitized carbon coating layer and the amorphous carbon coating layer is 1-10%.

3. The anode material according to claim 1 or 2, wherein the graphitized carbon coating layer comprises graphitized carbon material comprising one or two or more of mesophase carbon microspheres, carbon fibers, and carbon nanotubes.

4. The anode material according to claim 1 or 2, wherein the amorphous carbon coating layer comprises an amorphous carbon material formed from a carbon source.

5. The anode material according to claim 4, wherein the carbon source comprises a gaseous carbon source and/or a solid carbon source.

6. The anode material of claim 5, wherein the gaseous carbon source comprises C ₁ -C ₄ Alkane, C ₂ -C ₄ Olefins, C ₂ -C ₄ One or two or more alkynes of (a) are provided.

7. The anode material of claim 6, wherein the gaseous carbon source further comprises a borane or a phosphine.

8. The method for producing a negative electrode material according to claim 1, comprising:

by CoFe ₃ Sb ₁₂ Atomic vapor deposition is carried out by taking the alloy as a matrix and graphitized carbon material as a target material to obtain graphitized carbon coated CoFe ₃ Sb ₁₂ A composite material;

coating the graphitized carbon with CoFe in a carbon source environment ₃ Sb ₁₂ And carbonizing the composite material at high temperature to form an amorphous carbon coating layer to obtain the anode material.

9. A negative electrode sheet, characterized in that the negative electrode material according to any one of claims 1 to 7 is used as an active material.

10. A lithium ion battery comprising a positive electrode sheet, a separator, an electrolyte and the negative electrode sheet of claim 9.

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