A porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode active material and its preparation and application

Abstract

This invention belongs to the field of battery materials, specifically relating to a porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material, its preparation, and its application. The preparation method involves: depositing porous carbon in a silicon-containing atmosphere A, followed by a second deposition in an atmosphere B containing both silicon and carbon sources; then performing a third deposition in an atmosphere C containing Ti chloride gas, silicon chloride gas, and N source gas; and finally, performing a fourth deposition in an atmosphere D containing a carbon source to obtain the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material. The material described in this invention can effectively resist the high expansion stress of silicon materials based on its intrinsic physicochemical structure without the need for graphite, while still achieving excellent long-cycle performance.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery anode material technology, and particularly to a silicon-based anode material. Background Technology

[0002] With the increasing demand for lithium-ion batteries in energy storage systems, transportation and portable devices, and with current commercial graphite anodes having basically reached their theoretical capacity limit (372mAh / g), many commercial companies and researchers have been committed to developing materials with higher energy density that can replace carbon-based anodes in recent years.

[0003] Among numerous alternative materials such as transition metal oxides, tin-based and silicon-based materials, silicon anodes stand out due to their high theoretical specific capacity (4200 mAh / g) and moderate delithiation potential (0.4 V vs. Li / Li). + Silicon has become a research focus, and its abundant reserves and low cost in the Earth's crust make it one of the most promising next-generation lithium-ion battery anode materials. However, the lithium storage mechanism of silicon-based anodes is an alloying reaction mechanism, which involves huge volume expansion (>300%) during lithium insertion and huge volume contraction during delithiation. This repeated and drastic volume change causes silicon particles to break, pulverize, and fall off. The SEI film on the material surface also consumes lithium ions in the electrolyte during continuous rupture and formation, thus causing rapid capacity decay and a sharp decline in cycle performance.

[0004] To address the performance degradation issue caused by the massive expansion of silicon-based materials, existing technologies primarily utilize porous carbon materials to deposit silicon. For example, patent document CN114556621A discloses a negative electrode material comprising: a porous carbon material, a silicon-containing compound Si-MC, and a conductive carbon layer. The silicon-containing compound Si-MC is loaded within the pores of the porous carbon material, wherein M is one or more of B, N, O, and Al; the conductive carbon layer is located on the surface of the porous carbon material.

[0005] Patent document with publication number KR1020230039947A discloses a method for manufacturing a lithium anode plate with Si nanoparticles coated with porous carbon. Specifically, it describes a method for manufacturing a lithium anode plate with Si nanoparticles coated with porous carbon by coating an active material mixture containing Si nanoparticles coated with porous carbon on the surface, thereby improving the high conductivity and durability of the lithium anode plate. Furthermore, patent document CN118943337A discloses a method for preparing a porous silicon-carbon anode material coated with a fast ion conductor. The method involves pre-carbonizing a resin under a nitrogen atmosphere to obtain a carbon precursor; crushing the carbon precursor and mixing it with an alkali in a solid phase, followed by sequential activation and acid washing of the mixture to obtain a porous carbon material; depositing nano-silicon onto the surface of the porous carbon material using silane compounds to obtain a nano-silicon deposited porous carbon substrate; chemical vapor deposition of the nano-silicon deposited porous carbon substrate using a carbon source gas under a protective atmosphere to obtain a silane deposited porous carbon composite material; and then mixing the silane deposited porous carbon composite material, a metal salt, a phosphate solution, and an alkaline precipitant, followed by sequential reflux and calcination to obtain the porous silicon-carbon anode material coated with a fast ion conductor.

[0006] Porous carbon materials possess large specific surface area, good conductivity, and stability. Using porous carbon materials as a carbon framework, silane gas is introduced into the framework, and heating causes silicon nanoparticles to be uniformly deposited within the abundant pores of the porous carbon. However, as the number of deposited silicon nanoparticles increases, a certain number of silicon particles form during the vapor deposition process. These particles do not deposit on the carbon framework surface but exist independently. The average particle size of these silicon particles is greater than 150 nm, which reduces the electrochemical performance of the co-deposited silicon-carbon material. Furthermore, in existing silicon anode battery systems, silicon particles react chemically with fluorine in the electrolyte to form lithium fluorosilicate crystals, continuously consuming the limited lithium, silicon, and electrolyte resources in the battery system, ultimately leading to battery failure. The coated nanocarbon layer cannot prevent the contact between fluorine and silicon; instead, it lowers the activation energy of this reaction and accelerates the reaction process. Summary of the Invention

[0007] In view of the problems existing in the silicon materials of the prior art, the primary objective of this invention is to provide a method for preparing porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode materials, aiming to prepare silicon-based anode materials that have both excellent conductivity and long cycle stability.

[0008] The second objective of this invention is to provide a porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material prepared by the aforementioned method and its application in lithium-ion batteries.

[0009] A third objective of this invention is to provide a lithium-ion battery comprising the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material, as well as its anode and anode material.

[0010] A method for preparing a porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material involves first-stage deposition of porous carbon in an atmosphere A containing a silicon source, followed by second-stage deposition in an atmosphere B containing both a silicon source and a carbon source; then, a third-stage deposition process is performed in an atmosphere C containing Ti chloride gas, silicon chloride gas, and N source gas; finally, a fourth-stage deposition is performed in an atmosphere D containing a carbon source to obtain the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material.

[0011] This invention uses porous carbon as a substrate, performing a first-stage deposition process in atmosphere A, followed by a second-stage deposition in atmosphere B. This pre-forms silicon active sites on the porous carbon. Innovatively, a third-stage deposition process is then performed in atmosphere C containing Ti chloride gas, silicon chloride gas, and N source gas. This allows for the in-situ growth of a highly conductive and low-defect Ti₂CCl₂ / Ti₂NCl₂ layered composite material at the interface of the silicon active sites deposited in the first gas phase. A fourth-stage deposition process continues in atmosphere D, further coating amorphous carbon. The process described in this invention can prepare materials with high interfacial stability, high phase purity, and low defects. The material's stable structure effectively resists silicon expansion, significantly improving the electronic conductivity of the composite material and exhibiting high rate performance and long-cycle stability. The material described in this invention can effectively resist the high expansion stress of silicon materials based on its intrinsic physicochemical structure without the need for graphite, while still achieving excellent long-cycle performance.

[0012] In this invention, the porous carbon has a pore volume of 0.4~0.9 cm³. 3 / g, specific surface area of ​​900~2000m² 2 / g.

[0013] Furthermore, the porous carbon is obtained by carbonization with a carbon source; more preferably, it is obtained by carbonization with a resin carbon source. An optional preparation process for porous carbon according to the present invention is as follows: spherical resin is prepared by solution method, emulsion method, or other methods; the spherical resin is cured and carbonized to obtain resin-based spherical carbon; finally, the resin-based spherical carbon is activated to obtain resin-based spherical porous carbon.

[0014] In this invention, in atmosphere A, the silicon source includes at least one of hydrosilane, chlorosilane, dimethylsilane, diethylsilane, methylmonochlorosilane, methyldichlorosilane, and methyltrichlorosilane.

[0015] Preferably, atmosphere A further includes a dilution gas, which includes at least one of rare gases and nitrogen.

[0016] Preferably, the content of the silicon source in atmosphere A is 5~30v; more preferably, it can be 10~25v.

[0017] Preferably, the temperature of the first stage of deposition is 400~900℃; more preferably, it can be 500~650℃.

[0018] Preferably, the deposition time for the first stage is 0.5 to 3 hours, and more preferably 1 to 2 hours.

[0019] Atmosphere B is a mixed atmosphere containing a silicon source and a carbon source. Preferably, the silicon source includes at least one of hydrosilane, chlorosilane, dimethylsilane, diethylsilane, methylmonochlorosilane, methyldichlorosilane, and methyltrichlorosilane. Preferably, the carbon source includes at least one of alkanes, alkenes, alkynes, benzene, alcohols, aldehydes, and phenols that are gaseous during the second deposition process.

[0020] Preferably, atmosphere B further includes a dilution gas, which includes at least one of rare gases and nitrogen.

[0021] Preferably, in atmosphere B, the content of the silicon source is 5-30 vol% and the content of the carbon source is 5-30 vol%; further, the content of the silicon source is 10-20 vol% and the content of the carbon source is 10-20 vol%.

[0022] Preferably, the temperature of the second stage deposition is 400~900℃; more preferably, it can be 500~650℃.

[0023] Preferably, the deposition time for the second stage is 0.05 to 0.5 hours; more preferably, it can be 5 to 20 minutes.

[0024] Preferably, the first and second stages of deposition are cycled 2 to 4 times before the third stage of deposition is carried out.

[0025] In this invention, the total time for the first and second stages of deposition can be 2 to 5 hours.

[0026] In this invention, the Ti chloride gas includes at least one of titanium tetrachloride and titanium trichloride.

[0027] Preferably, the Ti chloride gas is passed through an atmosphere obtained by activating titanium tetrachloride with a titanium sponge.

[0028] Preferably, the temperature of the activation stage is 550~1200℃, for example, 900~1100℃.

[0029] In this invention, the silicon chloride gas includes at least one of chlorosilane, methylmonochlorosilane, methyldichlorosilane, and methyltrichlorosilane;

[0030] Preferably, the N source gas includes nitrogen.

[0031] Preferably, rare gases are also permitted to be present in atmosphere C.

[0032] Preferably, in atmosphere C, the volume content of Ti chloride gas is 1-10%, and the volume ratio of Ti chloride gas, silicon chloride gas, and N source gas is 1-8:0.1-4:1; more preferably, it can be 3-5:0.5-1:1.

[0033] In this invention, the temperature of the third stage deposition is 400~900℃, and can be further 600~700℃.

[0034] Preferably, the deposition time for the third stage is 5 to 60 minutes, and more preferably 10 to 25 minutes.

[0035] In this invention, in atmosphere D, the carbon source includes at least one of alkanes, alkenes, alkynes, benzene, alcohols, aldehydes, and phenols that are in a gaseous state during the fourth stage of deposition.

[0036] Preferably, atmosphere D may contain a dilution gas, which includes at least one of nitrogen and rare gases.

[0037] In atmosphere D, the content of carbon source components can be 5~15v.

[0038] Preferably, the temperature of the fourth deposition process is 400~900℃; more preferably, it can be 600~700℃.

[0039] Preferably, the deposition time for the fourth stage is 2 to 4 hours.

[0040] The present invention also provides a porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material prepared by the above preparation method.

[0041] The preparation method described in this invention can endow the prepared material with special physicochemical properties, and the material with special physicochemical properties obtained by the preparation method has excellent long-cycle performance.

[0042] The present invention also provides an application of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material prepared by the above preparation method, which is used as an anode active material for the preparation of lithium-ion batteries.

[0043] In this invention, based on known concepts, the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material can be used as an anode active material to prepare lithium-ion batteries and their anodes and anode materials.

[0044] The present invention also provides a negative electrode for a lithium-ion battery, comprising a current collector and a negative electrode material composite thereon, wherein the negative electrode material comprises a porous carbon@Ti2CCl2 / Ti2NCl2@Si composite negative electrode material prepared by the preparation method described in the present invention.

[0045] The negative electrode of the present invention, apart from containing the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite negative electrode material, can have conventional components, structures and parts.

[0046] The present invention also provides a lithium-ion battery comprising the negative electrode described herein.

[0047] The lithium-ion battery of the present invention, except for the negative electrode containing the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite negative electrode material of the present invention, may have other known components and structural parts.

[0048] Beneficial effects

[0049] This invention uses porous carbon as a substrate and sequentially performs a first stage of deposition in atmosphere A, a second stage of deposition in atmosphere B, a third stage of deposition in atmosphere C containing Ti chloride gas, silicon chloride gas, and N source gas, and a fourth stage of deposition in atmosphere D containing a carbon source. In this way, a porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material with high interface stability, low defects, and high phase purity can be formed on porous carbon. Moreover, this material effectively improves electronic conductivity and takes into account both good rate performance and excellent long-cycle stability. Attached Figure Description

[0050] Figure 1 This is a scanning electron microscope (SEM) image of the composite material prepared in Example 1.

[0051] Figure 2 This is the X-ray diffraction (XRD) spectrum of the composite material prepared in Example 1. The sharp peaks at 2θ of 28°, 47°, and 56° correspond to cubic silicon, consistent with standard card PDF#27-1402; the characteristic peak at 2θ of 10° corresponds to T... i2 NCl2 phase.

[0052] Figure 3 The image shows the charge / discharge specific capacity and voltage curves of the coin cell based on the composite material prepared in Example 1.

[0053] Figure 4It is the 1000-cycle retention rate of the composite materials prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0054] In this invention, the porous carbon is a resin-based spherical porous carbon with a pore volume of 0.4~0.9 cm³. 3 / g, specific surface area of ​​900~2000m² 2 / g. The preparation process of the porous carbon can be listed as follows: spherical resin is prepared by solution method, emulsion method, etc., the spherical resin is cured and carbonized to obtain resin-based spherical carbon, and finally the resin-based spherical carbon is activated to obtain resin-based spherical porous carbon.

[0055] In this invention, the percentage content of the components in the atmosphere refers to the volume percentage content.

[0056] Example 1

[0057] Step 1:

[0058] 1000g of porous carbon (pore volume 0.8m) 3 / g, specific surface area of ​​1800m² 2 The material (g) was placed in a fluidized bed deposition apparatus, argon was introduced as a protective gas and the air inside the apparatus was purged, and the temperature was raised to 550°C (marked as T1) at a heating rate of 5°C / min. Atmosphere A (a mixture of chlorosilane and Ar, with chlorosilane content of 20 v%) was introduced beforehand for the first deposition stage, with a deposition reaction time of 2 hours. Then, the atmosphere was switched to B (a mixture of chlorosilane, methane, and Ar, with chlorosilane content of 10 v% and methane content of 10 v%) for the second deposition stage (deposition reaction time of 15 minutes). Then, the first deposition process (deposition reaction time of 1 hour) and the second deposition process (deposition reaction time of 15 minutes) were repeated in sequence, for a total deposition time of 3.5 hours.

[0059] Step 2:

[0060] The activation zone containing the titanium sponge is heated to 1000°C (labeled as T2) at a heating rate of 10°C / min. Then, titanium source gas (a mixture of titanium tetrachloride and Ar, wherein the content of titanium tetrachloride is 8v%) is flowed through the titanium sponge at the temperature to convert the titanium source gas into activated titanium source gas (that is, to convert the titanium tetrachloride in it into titanium trichloride).

[0061] The final deposited product from step 1 was heated to 640°C (labeled T3) in an Ar atmosphere. Then, activated titanium source gas, silicon source gas (a mixture of silicon chloride and Ar, with a silicon chloride content of 2v%) and nitrogen source gas (a mixture of nitrogen and Ar (atmosphere C), with a nitrogen content of 2v%) were introduced to carry out the third stage of deposition (the volume ratio of the functional gases in the activated titanium source gas, silicon source gas, and nitrogen source gas during the third stage of deposition (i.e., the volume ratio of activated titanium source gas, silicon chloride, and nitrogen in atmosphere C) was 4:1:1). The deposition reaction time was 20 minutes. After the deposition was completed, nitrogen gas was introduced alone as a protective gas to purge for 20 minutes to obtain the Ti2CCl2 / Ti2NCl2 co-deposited material.

[0062] Step 3:

[0063] Surface carbon coating was performed by introducing acetylene gas (atmosphere D, containing acetylene:nitrogen in a volume ratio of 1:10) at 640℃ (labeled T4) for 3 hours. Finally, the material was cooled to obtain porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material.

[0064] Example 2

[0065] Compared with Example 1, the only difference is that in the first stage of deposition in step 1, the temperature T1 is 600°C, the atmosphere A is a dimethylsilane-Ar mixed atmosphere, wherein the content of dimethylsilane is 15v%; the first stage deposition time is 1h; the atmosphere B is a mixture of dimethylsilane, ethane, and Ar, wherein the content of dimethylsilane is 15v% and the content of ethane is 15v%; the second stage deposition time is 5min; the first stage deposition and the second stage deposition are repeated 3 times; other operations and parameters are the same as in Example 1.

[0066] Example 3

[0067] Compared with Example 1, the only difference is that the temperature T3 in the third stage of deposition in step 2 is set to 690°C, while other operations and parameters are the same as in Example 1.

[0068] Example 4

[0069] Compared with Example 1, the only difference is that in the third stage of deposition in step 2, the content of titanium tetrachloride in the titanium source gas is increased to 12v%; the content of nitrogen in the nitrogen source gas is increased to 3v%; and the content of silicon chloride in the silicon source gas remains unchanged at 2v% (the volume ratio of activated titanium source gas, silicon source gas, and nitrogen source in the third stage of deposition is 4:0.67:1).

[0070] In step 3, the temperature T4 is 690℃, and acetylene gas (containing acetylene:nitrogen gas with a volume ratio of 1:15) is used for surface carbon coating for 2 hours.

[0071] All other operations and parameters are the same as in Example 1.

[0072] Example 5

[0073] Compared with Example 1, the only difference is that the deposition reaction time in the third stage of step 2 is shortened to 10 minutes, while the other operations and parameters are the same as in Example 1.

[0074] Example 6

[0075] Compared with Example 1, the only difference is that the first and second stages of deposition in step 1 are performed only once. The first stage of deposition lasts for 3 hours, the second stage of deposition lasts for 0.5 hours, and the total deposition time remains 3.5 hours. All other operations and parameters are the same as in Example 1.

[0076] Comparative Example 1

[0077] Compared with Example 1, the only difference is that in the third stage of deposition in step 2, the atmosphere lacks the activation titanium source gas, and the nitrogen source gas is replaced with argon gas. All other operations and parameters are the same as in Example 1.

[0078] Comparative Example 2

[0079] Compared with Example 1, the only difference is that in the third stage of deposition in step 2, the nitrogen source gas in the atmosphere is replaced with argon gas, and all other operations and parameters are the same as in Example 1.

[0080] Some impurity phases such as TiC, Ti2C, and TiCl3 were formed.

[0081] Comparative Example 3

[0082] Compared with Example 1, the only difference is that in the third stage of deposition in step 2, the atmosphere lacks the activated titanium source gas; all other operations and parameters are the same as in Example 1.

[0083] Comparative Example 4

[0084] Compared with Example 1, the only difference is that step 2 is omitted, and step 3 is performed directly after step 1. All other operations and parameters are the same as in Example 1.

[0085] Comparative Example 5

[0086] Compared with Example 1, the only difference is that in step 1, the temperature T1 is 300°C, and all other operations and parameters are the same as in Example 1.

[0087] Comparative Example 6

[0088] Compared with Example 1, the only difference is that the activated titanium source gas and the nitrogen-silicon source gas are not carried out synchronously. That is, in the third stage of deposition in step 2, deposition is carried out in the activated titanium source gas (deposition time is 20 min), and then deposition is carried out in the silicon source gas and nitrogen source gas (deposition time is 20 min). After the deposition is completed, the processing in step 3 is carried out. Other operations and parameters are the same as in Example 1.

[0089] Some impurity phases such as TiC, Ti2C, and TiCl3 were formed.

[0090] Comparative Example 7

[0091] Compared with Example 1, the only difference is that the activated titanium source gas and the nitrogen-silicon source gas are not carried out synchronously. That is, in the third stage of deposition in step 2, deposition is carried out in a gas containing silicon source gas and nitrogen source gas (deposition time is 20 min), followed by deposition in activated titanium source gas (deposition time is 20 min). After the deposition is completed, the processing in step 3 is carried out. All other operations and parameters are the same as in Example 1.

[0092] Some impurity phases such as TiC, Ti2C, and TiCl3 were formed.

[0093] Comparative Example 8

[0094] Compared with Example 1, the only difference is that in step 1, the porous carbon is pre-deposited in the second stage, followed by the first stage deposition. All other operations and parameters are the same as in Example 1.

[0095] Performance testing

[0096] Figure 1 This is a scanning electron microscope (SEM) of the composite material prepared in Example 1 of the present invention.

[0097] Figure 2 This is the X-ray diffraction (XRD) spectrum of the composite material prepared in Example 1 of this invention. The sharp peaks at 2θ of 28°, 47°, and 56° correspond to cubic silicon, consistent with standard card PDF#27-1402; the characteristic peak at 2θ of 10° corresponds to T... i2 NCl2 phase.

[0098] The silicon-carbon anode active material used in the embodiments and comparative examples of this invention was mixed with polyacrylic acid binder (PAA) and conductive carbon black (SuperP) at a mass ratio of 80:10:10, using ultrapure water as a solvent, and stirred to form a slurry. This slurry was then uniformly coated onto copper foil. After coating, the slurry was dried in a vacuum drying oven at 120°C for 12 hours, and then rolled and punched to obtain a silicon-carbon anode sheet. Using the prepared anode sheet as the working electrode, a lithium metal sheet was used as the counter electrode. Celgard 2400 was selected as the separator, and 1 mol / L LiPF6 and a 1:1:1 EC / EMC / DMC electrolyte were used, with 10% FEC added. A coin cell was assembled in a glove box, and charge-discharge performance tests were performed. The test procedure was 0.1C discharge to 5mV and 0.1C charge to 1.5V.

[0099] The entire battery uses 18650 cylindrical cells. The composite negative electrode material obtained in the examples and comparative examples is mixed with the same stable artificial graphite. The initial reversible capacity of the mixed powder in coin cell testing is 500±5 mAh / g. The mixed powder is used to prepare negative electrode sheets according to coin cell technology, and the positive electrode is a 111-type NCM ternary positive electrode sheet prepared by a mature process. The separator and electrolyte are consistent with those of the coin cell. The resulting 18650 cylindrical single cell is assembled. The cycle capacity retention of the 18650 battery is tested using a charge-discharge test cabinet under the following conditions: room temperature, 3C / 2C charge-discharge, and charge-discharge voltage limited to 2.75V~4.2V.

[0100] The test results are shown in Table 1 below.

[0101] Figure 3 This is the charge / discharge specific capacity-voltage curve of the coin cell made of the composite material prepared in Example 1 of this invention.

[0102] Figure 4 It is the 1000-cycle retention rate of the composite materials prepared in Example 1 and Comparative Example 1 of the present invention.

[0103] The data for each case are shown in Table 1:

[0104]

[0105] After introducing Ti2CCl2 / Ti2NCl2 in Examples 1-6, the capacity and first efficiency deteriorated to some extent, but the 800-cycle retention rate was significantly improved, indicating that the introduction of Ti2CCl2 / Ti2NCl2 can suppress the cycle decay caused by volume expansion during discharge.

[0106] As can be seen from Examples 1 and 6, the use of cyclic first-stage deposition and second-stage deposition can effectively limit the particle size of silicon particles and optimize the particle composition structure within the pores, which helps to further improve the long-cycle performance of the material.

[0107] As can be seen from Examples 1 and Comparative Examples 1-8, using porous carbon as a substrate, the first stage of deposition is carried out in atmosphere A, the second stage in atmosphere B, the third stage in atmosphere C containing Ti chloride gas, silicon chloride gas, and N source gas, and the fourth stage in atmosphere D containing carbon source. In this way, a porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material with high interface stability, low defects, and high phase purity can be formed on porous carbon. Moreover, this material effectively improves electronic conductivity and takes into account both good rate performance and excellent long-cycle stability.

[0108] It should be understood that the present invention is not limited to the processes and structures described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing a porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material, characterized in that, Porous carbon was first deposited in atmosphere A containing a silicon source, and then secondly deposited in atmosphere B containing both silicon and carbon sources. A third stage of deposition is then performed in an atmosphere C containing Ti chloride gas, silicon chloride gas, and N source gas; finally, a fourth stage of deposition is performed in an atmosphere D containing a carbon source to obtain the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material.

2. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, The porous carbon has a pore volume of 0.4~0.9 cm³. 3 / g, specific surface area of ​​900~2000m² 2 / g.

3. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 2, characterized in that, The porous carbon is obtained by carbonization using a carbon source.

4. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 3, characterized in that, The porous carbon is obtained by carbonization with a resin carbon source.

5. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, In atmosphere A, the silicon source includes at least one of hydrosilane, chlorosilane, dimethylsilane, diethylsilane, methylmonochlorosilane, methyldichlorosilane, and methyltrichlorosilane.

6. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 5, characterized in that, Atmosphere A also contains a dilution gas, which includes at least one of rare gases and nitrogen.

7. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 5, characterized in that, The content of the silicon source described in Atmosphere A is 5~30V.

8. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, The temperature of the first sedimentary stage is 400~900℃.

9. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 8, characterized in that, The first deposition period is 0.5 to 3 hours.

10. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, Atmosphere B is a mixed atmosphere containing silicon and carbon sources; The silicon source includes at least one of hydrosilane, chlorosilane, dimethylsilane, diethylsilane, methylmonochlorosilane, methyldichlorosilane, and methyltrichlorosilane; The carbon source includes at least one of alkanes, alkenes, alkynes, benzene, alcohols, aldehydes, and phenols that are gaseous during the second deposition process.

11. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 10, characterized in that, Atmosphere B also contains a dilution gas, which includes at least one of rare gases and nitrogen.

12. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 11, characterized in that, In atmosphere B, the content of the silicon source is 5-30 vol%, and the content of the carbon source is 5-30 vol%.

13. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 11, characterized in that, The temperature of the second stage of deposition is 400~900℃; The second deposition period is 0.05~0.5h.

14. The preparation method of the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, The first and second stages of deposition are repeated 2 to 4 times before the third stage of deposition begins.

15. The method for preparing the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, The Ti chloride gas includes at least one of titanium tetrachloride and titanium trichloride.

16. The method for preparing the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, The Ti chloride gas is the atmosphere after titanium tetrachloride has been activated by a titanium sponge; The activation temperature is 550~1200℃.

17. The method for preparing the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, The silicide gas includes at least one of chlorosilane, methylmonochlorosilane, methyldichlorosilane, and methyltrichlorosilane; N-source gases include nitrogen.

18. The method for preparing the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, In atmosphere C, rare gases are also permitted. In atmosphere C, the volume content of Ti chloride gas is 1~10%, and the volume ratio of Ti chloride gas, silicon chloride gas, and N source gas is 1~8:0.1~4:

1.

19. The method for preparing the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, The temperature of the third sedimentation stage is 400~900℃; The third stage of deposition takes 5 to 60 minutes.

20. The method for preparing the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, In atmosphere D, the carbon source includes at least one of alkanes, alkenes, alkynes, benzene, alcohols, aldehydes, and phenols that are gaseous during the fourth stage of deposition.

21. The method for preparing the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 20, characterized in that, Atmosphere D may contain a dilution gas, which includes at least one of nitrogen and rare gases.

22. The method for preparing the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material as described in claim 1, characterized in that, The temperature of the fourth depositional stage is 400~900℃; The fourth deposition period is 2-4 hours.

23. A porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material prepared by the preparation method according to any one of claims 1 to 22.

24. The application of a porous carbon@Ti2CCl2 / Ti2NCl2@Si composite anode material prepared by the method according to any one of claims 1 to 22, characterized in that, It is used as a negative electrode active material in the preparation of lithium-ion batteries.

25. A negative electrode for a lithium-ion battery, comprising a current collector and a negative electrode material composited thereon, characterized in that, The negative electrode material includes the porous carbon@Ti2CCl2 / Ti2NCl2@Si composite negative electrode material prepared by the preparation method according to any one of claims 1 to 22.

26. A lithium-ion battery, characterized in that, It includes the negative electrode as described in claim 25.

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