Method for preparing silicon-carbon composite material from liquid silane, silicon-carbon composite material and use

Abstract

The application discloses a method for preparing silicon-carbon composite material by liquid silane, silicon-carbon composite material and application, and at least comprises operation steps: S1), placing porous carbon raw materials into a reaction kettle, introducing steam formed by heating a solution into the reaction kettle under a vacuum environment, realizing liquid silane deposition on the porous carbon particles under a heating condition, and obtaining a silicon-carbon precursor material; wherein the solution is formed by mixing polycarbosilane, an organic catalyst and an organic solvent; S2), under an environment with a dew point of less than or equal to-20 DEG C, transferring the silicon-carbon precursor material obtained in the step S1) into a vapor deposition furnace, introducing an organic metal compound in a gaseous state into the vapor deposition furnace under a heating condition, and performing vapor deposition on the silicon-carbon precursor material; the application not only maintains the basic technical advantages of preparing silicon-carbon material by liquid silane method, but also has good structural stability of the obtained silicon-carbon composite material, and excellent performance after being applied to a battery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of lithium ion battery material preparation, and particularly relates to a method for preparing silicon-carbon composite material by liquid silane, and further relates to the silicon-carbon composite material obtained by the preparation method and the application thereof. BACKGROUND

[0002] In the current technology, the silicon-carbon material prepared by the silane cracking method is applied in high specific energy density lithium ion batteries due to its high energy density, low expansion, good cycle performance and other advantages. However, the gas silane cracking method has high requirements for the environment, and the high cracking temperature causes the silicon grains to be relatively large, the expansion to be slightly high, and the H2 tail gas generated by the cracking of SiH4 to have relatively large safety hazards, making it difficult to mass-produce and resulting in high manufacturing costs. The preparation of silicon-carbon material by liquid silane cracking method has the advantages of not being harsh on the manufacturing environment, low reaction temperature and small safety hazards, but due to the low cracking temperature, the structure stability of nano-silicon and amorphous carbon is poor, resulting in low storage and first efficiency, so the preparation of silicon-carbon material by liquid silane cracking method is still difficult to be truly applied in high specific energy density lithium ion batteries.

[0003] The patent application with the publication number CN114556621A discloses a preparation method of negative electrode material, specifically proposes: dissolving a silicon source in an organic solvent to obtain a first mixture; mixing and stirring the porous carbon material with the first mixture, then heating to remove the solvent, and drying the obtained product to obtain a dried product; high-temperature cracking the dried product to obtain a Si-M-C@ porous carbon material; forming a conductive carbon layer on the surface of the Si-M-C@ porous carbon material to obtain the negative electrode material; although this method mentions the preparation of liquid silane, the liquid silane is dried during implementation, and then the dried product needs to be cracked by high temperature, which causes the advantages of the preparation of silicon-carbon material by liquid silane cracking method to disappear.

[0004] Therefore, based on the concentrated research experience of the applicant in this field, a new technical solution is sought to solve the above technical problems. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a method for preparing silicon-carbon composite material by liquid silane, silicon-carbon composite material and application, which not only maintains the basic technical advantages of the preparation of silicon-carbon material by liquid silane method, but also has good structure stability of the silicon-carbon composite material obtained by the present application, excellent performance after application in batteries, and effectively promotes the development process of mass application of silicon-carbon material prepared by liquid silane method in high specific energy density lithium ion batteries.

[0006] The technical solution adopted by the present application is as follows:

[0007] A method for preparing a silicon-carbon composite material by liquid silane, comprising at least the following steps:

[0008] S1), placing a porous carbon raw material into a reaction kettle, under vacuum environment, introducing steam formed by heating a solution into the reaction kettle, and depositing liquid silane on the porous carbon particles under heating conditions to obtain a silicon-carbon precursor material; wherein the solution is formed by mixing polycarbosilane, an organic catalyst and an organic solvent;

[0009] S2), transferring the silicon-carbon precursor material obtained in the above step S1) into a vapor deposition furnace under an environment with a dew point ≤-20℃, introducing an organic metal compound in a gaseous state into the vapor deposition furnace under heating conditions, and performing vapor deposition on the silicon-carbon precursor material;

[0010] S3), obtaining a metal-doped amorphous carbon-coated silicon-carbon composite material as the silicon-carbon composite material.

[0011] Preferably, in the solution, the mass ratio of polycarbosilane: organic catalyst: organic solvent ranges from 100:1 to 50:500-1000, preferably from 100:1 to 20:500-1000, and more preferably from 100:1 to 10:500-1000; the solution is obtained after the polycarbosilane and the organic catalyst are uniformly dispersed in the organic solvent.

[0012] Preferably, the organic catalyst is selected from any one or mixture of several of ethyl ferrocene, 2,2-bis(ethylferrocene)propane, and ferrocene cyclopentadiene; and / or, the organic solvent is selected from any one or mixture of several of tetrahydrofuran, dichloromethane, n,n-dimethylformamide, n,n-dimethylacetamide, and toluene.

[0013] Preferably, in the step S1), the reaction kettle is vacuumed to not higher than 0.1 Torr, and then steam formed by heating a solution is introduced into the reaction kettle, and the liquid silane is deposited on the porous carbon particles under heating to a temperature of 250-500℃.

[0014] Preferably, the porous carbon raw material has a pore size distribution ranging from 5-20 nm, and / or a specific surface area ranging from 300-800 m 2 / g, and / or a porosity ranging from 50-80%.

[0015] Preferably, in the step S2), the silicon-carbon precursor material obtained in the step S1) is transferred into a vapor deposition furnace under the environment of dew point ≤-50℃, and the organic metal compound in gaseous state is introduced into the vapor deposition furnace under the condition of heating to the temperature of 200-300℃.

[0016] Preferably, the organic metal compound is selected from any one or mixture of several of zinc dialkyldithiophosphate, copper dialkyldithiophosphate, molybdenum dialkyldithiophosphate, and cerium dialkyldithiophosphate.

[0017] Preferably, the organic metal compound is heated to 500-1000℃ for gasification to obtain the organic metal compound in gaseous state.

[0018] Preferably, a silicon-carbon composite material is obtained by the method for preparing a silicon-carbon composite material from liquid silane as described above.

[0019] Preferably, the silicon-carbon composite material as described above is applied as the active material raw material for preparing a battery pole piece, preferably as the active material raw material for a lithium ion battery negative pole piece.

[0020] The present application firstly adopts a liquid silane solution prepared by mixing polycarbosilane, an organic catalyst, and an organic solvent, heats the solution to form a vapor, and then makes the porous silicon particle raw material complete liquid silane deposition in the form of solution vapor; at the same time, the organic metal compound in gaseous state is coated on the surface of the silicon-carbon material by low-temperature cracking carbonization through the gas phase deposition method. The present applicant surprisingly finds that the preparation method provided by the present application not only maintains the basic technical advantages of the liquid silane method for preparing silicon-carbon materials: low reaction temperature, low preparation environment requirement, low cost, and small silicon crystal grains in the obtained silicon-carbon composite material, low expansion, and other advantages; at the same time, the unique low-temperature cracking gas phase deposition method of the organic metal compound realizes metal doping and amorphous carbon coating of the silicon-carbon precursor material at the same time, effectively avoids direct contact of the nano-silicon with the electrolyte, reduces the side reaction, and improves the high-temperature storage performance; and the structure stability of the silicon-carbon composite material obtained by the present application is good, the performance after application in a battery is excellent, and the development process of batch application of the liquid silane method for preparing silicon-carbon materials in high specific energy density lithium ion batteries is effectively promoted. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a preparation step block diagram of the silicon-carbon composite material in the specific embodiment of the present application;

[0022] Figure 2 is an SEM image of the silicon-carbon composite material prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0023] Please refer toFigure 1 As shown, the present embodiment provides a method for preparing silicon-carbon composite material by liquid silane, comprising the following operation steps:

[0024] S1), placing the porous carbon raw material into a reaction kettle, under vacuum environment (preferably, vacuum extraction to 0.1 Torr or lower than 0.1 Torr), introducing steam formed by heating the solution into the reaction kettle, under heating condition (preferably, heating to a temperature condition of 250-500°C), realizing liquid silane deposition on the porous carbon particles (deposition time of at least 20 minutes, preferably 30 minutes-6 hours, more preferably 1-4 hours), to obtain a silicon-carbon precursor material; wherein the solution is mixed by polycarbosilane, organic catalyst and organic solvent;

[0025] Preferably, in order to facilitate the liquid silane deposition effect of the porous carbon, in the present step S1), the pore size distribution range of the selected porous carbon raw material is 5-20 nm, and / or the specific surface area range thereof is 300-800 m 2 / g, and / or the porosity range thereof is 50-80%;

[0026] Preferably, when preparing the solution in the present step S1), polycarbosilane and organic catalyst are added into the organic solvent to disperse uniformly, wherein, preferably, in the present embodiment, the organic catalyst is selected from any one or mixture of several of ethyl ferrocene, 2,2-bis(ethyl ferrocene) propane, and ferrocene; preferably, in the present embodiment, the organic solvent is selected from any one or mixture of several of tetrahydrofuran, dichloromethane, n,n-dimethylformamide, n,n-dimethylacetamide, and toluene; preferably, in the present embodiment, the mass ratio of polycarbosilane: organic catalyst: organic solvent in the solution ranges from 100:1-50:500-1000, preferably 100:1-20:500-1000, more preferably 100:1-10:500-1000;

[0027] S2), since the silicon-carbon precursor material will explode when encountering moisture in the air and will react violently with oxygen, in order to ensure the safe operation during preparation of the present embodiment, under an environment with dew point ≤-20°C, preferably under an environment with dew point ≤-30°C, more preferably under an environment with dew point ≤-50°C, the silicon-carbon precursor material obtained in the above step S1) is transferred into a vapor deposition furnace (preferably a tube-type deposition furnace), under heating condition (preferably heating to a temperature condition of 200-300°C), gaseous organic metal compound is introduced into the vapor deposition furnace, and vapor deposition is carried out on the silicon-carbon precursor material, preferably, the vapor deposition time is at least 20 minutes, preferably 30 minutes-6 hours, more preferably 1-4 hours;

[0028] Preferably, in the present step S2), the organometallic compound is selected from any one or a mixture of several of zinc dialkyldithiophosphate, copper dialkyldithiophosphate, molybdenum dialkyldithiophosphate, cerium dialkyldithiophosphate; particularly preferably, the organometallic compound is heated to 500-1000℃ for vaporization, and then the organometallic compound in a vaporized state is obtained.

[0029] S3), obtaining a metal-doped amorphous carbon-coated silicon-carbon composite material, also obtaining the target silicon-carbon composite material of the present embodiment.

[0030] Preferably, the present embodiment proposes a silicon-carbon composite material, which is obtained by using the method for preparing a silicon-carbon composite material from a liquid silane as described above in the present embodiment.

[0031] Preferably, the present embodiment also proposes an application of a silicon-carbon composite material, using the silicon-carbon composite material provided by the present embodiment as an active material raw material for preparing a battery pole piece, preferably as an active material raw material for a lithium ion battery negative pole piece.

[0032] The person skilled in the art can make specific applications according to actual needs during implementation, and the specific application method shall belong to the routine technical means of the person skilled in the art, thus the present embodiment does not particularly limit the application mode.

[0033] In order to enable the person skilled in the art to better understand the technical solutions in the present application, the technical solutions in the present embodiment will be described clearly and completely below in combination with the drawings in the present embodiment. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without making creative efforts shall belong to the protection scope of the present application.

[0034] On the basis of the above-described embodiments, the present application further proposes the following specific embodiments:

[0035] Embodiment 1: The silicon-carbon composite material in the present embodiment 1 is prepared according to the following operation steps:

[0036] S1), preparing a silicon-carbon precursor material:

[0037] First, 100g of polycarbosilane and 5g of ethyl ferrocene are added to 800g of tetrahydrofuran organic solvent for uniform dispersion, obtaining a solution, which is heated to form a solution vapor;

[0038] The porous carbon raw material (with a pore size distribution of 10nm and a specific surface area of 500m 2The porous carbon raw material (pore size distribution of 10 nm, specific surface area of 500 m 2 / g, porosity of 60%) is transferred into a reaction kettle, vacuum is drawn to 0.1 Torr, solution vapor is introduced into the reaction kettle, and deposition is carried out in the porous carbon at a temperature of 250 DEG C for 3 hours to obtain a silicon-carbon precursor material;

[0039] S2), vapor deposition:

[0040] First, zinc dialkyldithiophosphate is selected as an organometallic compound, and is heated to 800 DEG C for gasification to obtain zinc dialkyldithiophosphate in a gaseous state;

[0041] The silicon-carbon precursor material is transferred into a tube-type deposition furnace under a dew point of less than or equal to -50 DEG C, and heated to a temperature of 250 DEG C, and the zinc dialkyldithiophosphate in the gaseous state is introduced into the tube-type deposition furnace to carry out vapor deposition on the silicon-carbon precursor material for 1 hour;

[0042] S3), a metal-doped amorphous carbon-coated silicon-carbon composite material, that is, the target silicon-carbon composite material product of this embodiment 1, is obtained.

[0043] The silicon-carbon composite material obtained in this embodiment 1 is subjected to SEM (scanning electron microscope) morphology testing, and the test results are shown in FIG. 1. Figure 2 As can be seen from FIG. 1, the silicon-carbon composite material has a granular structure, and the particle size D50 is between 5-10 μm. Figure 2

[0044] Embodiment 2: The silicon-carbon composite material is prepared according to the following operation steps in this embodiment 2:

[0045] S1), preparation of a silicon-carbon precursor material:

[0046] First, 100 g of polycarbosilane and 1 g of 2,2-bis(ethylferrocenyl)propane are added into 500 g of dichloromethane organic solvent for uniform dispersion to obtain a solution, and the solution is heated to form solution vapor;

[0047] The porous carbon raw material (pore size distribution of 10 nm, specific surface area of 500 m 2 / g, porosity of 60%) is transferred into a reaction kettle, vacuum is drawn to 0.1 Torr, solution vapor is introduced into the reaction kettle, and deposition is carried out in the porous carbon at a temperature of 250 DEG C for 3 hours to obtain a silicon-carbon precursor material;

[0048] S2), vapor deposition:

[0049] First, copper dialkyldithiophosphate is selected as an organometallic compound, and is heated to 500 DEG C for gasification to obtain copper dialkyldithiophosphate in a gaseous state;

[0050] The silicon-carbon precursor material is transferred into a tube deposition furnace under the condition of dew point ≤-50℃, heated to a temperature of 200℃, and copper dialkyldithiophosphate in gaseous state is introduced into the tube deposition furnace to perform vapor deposition on the silicon-carbon precursor material for 2 hours.

[0051] S3), a metal-doped amorphous carbon-coated silicon-carbon composite material, i.e., the target silicon-carbon composite material product of this embodiment 2, is obtained.

[0052] Embodiment 3: The silicon-carbon composite material is prepared according to the following operation steps in this embodiment 3:

[0053] S1), preparation of a silicon-carbon precursor material:

[0054] First, 100g of polycarbosilane and 10g of dicyclopentadiene iron are added into 1000g of n,n-dimethylformamide organic solvent to be uniformly dispersed to obtain a solution, and the solution is heated to form a solution vapor;

[0055] The porous carbon raw material (pore size distribution of 5nm, specific surface area of 800m 2 / g, porosity of 50%) is transferred into a reaction kettle, vacuumized to 0.1 Torr, and then the solution vapor is introduced into the reaction kettle, heated to a temperature of 500℃, and deposition is performed in the porous carbon for 30 minutes to obtain a silicon-carbon precursor material;

[0056] S2), vapor deposition:

[0057] First, molybdenum dialkyldithiophosphate is selected as an organic metal compound, heated to 1000℃ for gasification to obtain molybdenum dialkyldithiophosphate in gaseous state;

[0058] The silicon-carbon precursor material is transferred into a tube deposition furnace under the condition of dew point ≤-50℃, heated to a temperature of 300℃, and molybdenum dialkyldithiophosphate in gaseous state is introduced into the tube deposition furnace to perform vapor deposition on the silicon-carbon precursor material for 30 minutes;

[0059] S3), a metal-doped amorphous carbon-coated silicon-carbon composite material, i.e., the target silicon-carbon composite material product of this embodiment 3, is obtained.

[0060] Comparative Example 1: The remaining technical solutions of this comparative example 1 are the same as those of embodiment 1, except that in this comparative example 1, the silicon-carbon precursor material obtained in step S1) of embodiment 1 is transferred into a tube deposition furnace, argon gas is first introduced to remove air in the tube, then acetylene gas is introduced and heated to 700℃ for 1 hour to obtain the silicon-carbon composite material of comparative example 1.

[0061] Comparative Example 2: 100 g of the solution in step S1) of Example 1 and 10 g of the porous carbon raw material were weighed respectively, mixed uniformly by a ball mill, and then spray dried to obtain a silicon-carbon precursor material; the silicon-carbon precursor material was transferred into a tube-type deposition furnace under an environment with a dew point ≤-50℃, and copper dialkyldithiophosphate in a gaseous state was introduced into the tube-type deposition furnace under the condition of heating to a temperature of 200℃, and vapor deposition was performed on the silicon-carbon precursor material for 2 hours to obtain the silicon-carbon composite material of Comparative Example 2.

[0062] Comparative Example 3: The remaining technical solutions of Comparative Example 3 are the same as those of Example 1, except that in Comparative Example 3, the silicon-carbon precursor material obtained in step S1) of Example 1 is used, and the phenolic resin is mixed with the silicon-carbon precursor material, and then the mixture is transferred into a tube-type deposition furnace and subjected to high-temperature carbonization sintering under the condition of heating to a temperature of 900℃ in an inert atmosphere to obtain the silicon-carbon composite material of Comparative Example 3.

[0063] Comparative Example 4: The remaining technical solutions of Comparative Example 4 are the same as those of Example 1, except that in Comparative Example 4, the silicon-carbon precursor material obtained in step S1) of Example 1 is used, and the sodium silicate is mixed with the silicon-carbon precursor material, and then the mixture is transferred into a tube-type deposition furnace and subjected to high-temperature carbonization sintering under the condition of heating to a temperature of 900℃ in an inert atmosphere to obtain the silicon-carbon composite material of Comparative Example 4.

[0064] Comparative Example 5: The remaining technical solutions of Comparative Example 5 are the same as those of Example 1, except that in Comparative Example 5, the silicon compound Si-M-C provided in CN114556621A is used instead of the silicon-carbon precursor material obtained in step S1) of Example 1, and the silicon-carbon composite material of Comparative Example 5 is obtained after step S2) of Example 1.

[0065] Comparative Example 6: The remaining technical solutions of Comparative Example 6 are the same as those of Example 1, except that in Comparative Example 6, the product obtained by the following steps is used instead of the silicon-carbon precursor material obtained in step S1) of Example 1: the silicon-carbon composite material of Comparative Example 6 is obtained after step S2) of Example 1.

[0066] A porous carbon raw material (pore size distribution: 10 nm, specific surface area: 500 m 2 / g, porosity: 60%) was used as a substrate, which was transferred into a reaction device, vacuumed, and then continuously introduced with silane gas through the inlet and discharged with hydrogen gas through the outlet, and heated to 500-700℃ for 3 hours.

[0067] In order to compare and verify the effects of the above examples and comparative examples, the silicon-carbon composite materials obtained in Examples 1-3 and Comparative Examples 1-6 were subjected to the following physical and chemical properties and button cell tests:

[0068] 1). The particle size, tap density, specific surface area, silicon crystal grains, powder resistivity, and specific capacity of each silicon-carbon composite material obtained in Examples 1-3 and Comparative Examples 1-6 were tested according to the method in the national standard GB / T 38823-2020 “Silicon-carbon”; the test results are shown in Table 1 below.

[0069] 2). Button cell test:

[0070] Each silicon-carbon composite material obtained in Examples 1-3 and Comparative Examples 1-6 was used as the active material of the battery negative electrode sheet to prepare nine button cells, which were labeled as A1, A2, A3, B1, B2, B3, B4, B5, and B6, respectively. The specific preparation process of each button cell was as follows:

[0071] Preparation of battery negative electrode sheet: a binder, a conductive agent, and a solvent were added to each silicon-carbon composite material (as the active material of the battery negative electrode sheet) corresponding to Examples 1-3 and Comparative Examples 1-6, respectively, and stirring was performed to form a slurry, which was coated on a copper foil, and then dried and rolled to obtain each battery negative electrode sheet. The binder was LA132 binder, the conductive agent was SP (conductive carbon black), and the solvent was double-distilled water, and the ratio was: silicon-carbon composite material: SP: LA132: double-distilled water = 95 g: 1 g: 4 g: 220 mL.

[0072] Preparation of button cell: the electrolyte was a LiPF6 solution, wherein the concentration of LiPF6 was 1.3 mol / L, and the solvent used was a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DMC) with a weight ratio of 1:1; a metal lithium sheet was used as the counter electrode, and a polyethylene (PE) separator was used; the simulation battery was assembled in an argon-filled glove box, and the electrochemical performance was tested on a Wuhan Lan Electric CT2001A battery tester, with the test conditions being: the charge and discharge voltage range was 0.005 V to 2.0 V, and the charge and discharge rate was 0.1 C; the rate (2C / 0.1C) and the cycle performance (test conditions: 0.2C / 0.2C, 200 cycles) of the button cell were also tested; the test results are shown in Table 1 below.

[0073] Table 1

[0074]

[0075] As can be seen from Table 1, the silicon-carbon composite material provided by the embodiments 1-3 has a high specific surface area, and the pouch battery prepared therefrom has excellent first discharge specific capacity, first efficiency, rate performance and cycle performance; the experimental results show that the silicon-carbon composite material (as the negative electrode active material of the battery) provided by the present application is doped with an organic catalyst and filled into the surface of the silicon-based particulate material through vacuum infiltration, so that it has low impedance, and the low-temperature pyrolysis and carbonization of the organic metal compound on the surface of the silicon-carbon material can further reduce the impedance and improve the rate and cycle performance.

[0076] 3). Pouch battery test:

[0077] Each silicon-carbon composite material obtained from the embodiments 1-3 and the comparative examples 1-6 was doped with 90% artificial graphite as a negative electrode material (i.e. as a negative electrode sheet), and a ternary material LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 as a positive electrode material, an electrolyte and a separator to assemble a 5 Ah pouch battery; wherein the separator of the pouch battery is Celegard2400, the electrolyte is a LiPF6 solution, the solvent of the LiPF6 solution is a mixed solution of EC and DEC at a volume ratio of 1:1, and the concentration of LiPF6 is 1.3 mol / L; each pouch battery prepared from each silicon-carbon composite material of the embodiments 1-3 and the comparative examples 1-6 was marked as C1, C2, C3, D1, D2, D3, D4, D5, D6 and each battery negative electrode sheet corresponding thereto, and the liquid absorption capacity and liquid retention capacity of each negative electrode sheet were tested, and the test results are shown in Table 2.

[0078] The test process of the liquid absorption capacity is as follows: a 1 mL burette is used, and VmL of electrolyte is taken, the electrolyte is added dropwise on the surface of the negative electrode sheet, timing is performed until the electrolyte is completely absorbed, the time t is recorded, and the liquid absorption speed V / t of the negative electrode sheet is calculated.

[0079] The test process of the liquid retention capacity is as follows: the theoretical liquid absorption amount m1 of the negative electrode sheet is calculated according to the negative electrode sheet parameters, and the weight m2 of the negative electrode sheet is weighed, then the negative electrode sheet is placed in the electrolyte for 24 hours, the weight of the negative electrode sheet is weighed as m3, the liquid absorption amount m3-m2 of the negative electrode sheet is calculated, and the liquid retention rate is calculated according to the following formula: liquid retention rate = (m3-m2)*100% / m1.

[0080] Table 2

[0081]

[0082]

[0083] From Table 2 above, it can be seen that the liquid absorption and retention capacity of the negative electrode sheet made of the silicon-carbon composite material provided in the embodiments 1-3 of the present application is obviously superior to that of the comparative examples 1-6, which may be mainly due to the fact that the specific surface area of the silicon-carbon composite material provided in the embodiments can obviously improve the liquid absorption and retention capacity of the electrode sheet.

[0084] The rate performance and cycle performance of each soft package battery were also tested, and the test results are shown in Table 3 and Table 4, respectively. In Table 3, the rate performance test conditions are as follows: the charge and discharge voltage range is 2.5-4.2 V, the temperature is 25±3.0℃, each button type battery is charged at 1.0C, 3.0C, 5.0C, 10.0C and 20.C, respectively, and discharged at 1.0C; in Table 4, the cycle performance test conditions are as follows: the charge and discharge current is 2C / 2C, the voltage range is 2.8-4.2V, and the cycle number is 500 times.

[0085] Table 3

[0086]

[0087]

[0088] From Table 3 above, it can be seen that the rate charge performance of the soft package battery made of the silicon-carbon composite material provided in the embodiments 1-3 of the present application is obviously superior to that of the comparative examples 1-6, that is, the soft package battery made by the embodiments of the present application has shorter and faster charging time, which may be due to the fact that the special porous metal frame structure used in the embodiments of the present application significantly improves the rate performance.

[0089] Table 4

[0090] Silicon-carbon composite material employed Initial capacity retention (%) Retention after 500 cycles (%) Example 1 100 95.02 Example 2 100 94.95 Example 3 100 93.81 Comparative Example 1 100 91.12 Comparative Example 2 100 90.89 Comparative Example 3 100 92.4 Comparative Example 4 100 88.4 Comparative Example 5 100 92.9 Comparative Example 6 100 85.4

[0091] From Table 4 above, it can be seen that the cycle performance of the soft package battery made of the silicon-carbon composite material provided in the embodiments 1-3 of the present application is obviously superior to that of the comparative examples 1-6 at each stage, which may be due to the fact that the carbon-silicon composite material provided in the present application has good structural stability, thereby significantly improving the cycle performance of the applied battery.

[0092] It is apparent for those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and the present application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all aspects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the foregoing description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the elements of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

[0093] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes every feature described. The specification can include implicit combinations of explicitly mentioned features and / or explicit combinations of implicitely mentioned features. Each embodiment depends on the explicit combinations of features and / or the implicit combinations of features made specifically within that embodiment, and each such embodiment can be combined with every other such embodiment to create further embodiments.

Claims

1. A method for producing a silicon-carbon composite material from a liquid silane, characterized by, At least comprising the following operation steps: S1), placing a porous carbon raw material into a reaction kettle, under a vacuum environment, introducing steam formed after heating a solution into the reaction kettle, under a heating condition, realizing liquid silane deposition on the porous carbon particles to obtain a silicon-carbon precursor material; wherein the solution is formed by mixing polycarbosilane, an organic catalyst and an organic solvent; in the step S1), the reaction kettle is vacuumed to not higher than 0.1 Torr, then steam formed after heating the solution is introduced into the reaction kettle, and heated to a temperature condition of 250-500°C to realize liquid silane deposition on the porous carbon particles; the porous carbon raw material has a pore size distribution range of 5-20 nm, and / or a specific surface area range of 300-800 m 2 / g, and / or a porosity range of 50-80%; S2), under the environment of dew point ≤-20℃, transferring the silicon-carbon precursor material obtained in step S1) into a vapor deposition furnace, and under the heating condition, introducing the organic metal compound in the gaseous state into the vapor deposition furnace to perform vapor deposition on the silicon-carbon precursor material; the organic metal compound is selected from any one or mixture of several of zinc dialkyldithiophosphate, copper dialkyldithiophosphate, molybdenum dialkyldithiophosphate, and cerium dialkyldithiophosphate; S3), obtaining the metal-doped amorphous carbon-coated silicon-carbon composite material as the silicon-carbon composite material.

2. The method for preparing silicon-carbon composite materials from liquid silane according to claim 1, characterized in that, In the solution, the mass ratio of polycarbosilane: organic catalyst: organic solvent ranges from 100:1-50:500-1000; after the polycarbosilane and organic catalyst are uniformly dispersed in the organic solvent, the solution is obtained.

3. The method for preparing silicon-carbon composite materials from liquid silane according to claim 2, characterized in that, In the solution, the mass ratio of polycarbosilane: organic catalyst: organic solvent ranges from 100:1-20:500-1000.

4. The method for preparing silicon-carbon composite materials from liquid silane according to claim 2, characterized in that, In the solution, the mass ratio of polycarbosilane: organic catalyst: organic solvent ranges from 100:1-10:500-1000.

5. The process for the production of silicon-carbon composite materials from liquid silane according to claim 1 or 2 or 3 or 4, characterized in that, The organic catalyst is selected from any one or mixture of several of ethyl ferrocene, 2,2-bis(ethylferrocenyl)propane, and ferrocene dicyclopentadiene; and / or, the organic solvent is selected from any one or mixture of several of tetrahydrofuran, dichloromethane, n,n-dimethylformamide, n,n-dimethylacetamide, and toluene.

6. The method for preparing silicon-carbon composite materials from liquid silane according to claim 1, characterized in that, In the step S2), under the environment of dew point ≤-50℃, transferring the silicon-carbon precursor material obtained in step S1) into a vapor deposition furnace, and heating to the temperature condition of 200-300℃, introducing the organic metal compound in the gaseous state into the vapor deposition furnace.

7. The method for preparing silicon-carbon composite materials from liquid silane according to claim 1, characterized in that, The organic metal compound is heated to 500-1000℃ to be gaseous, and the organic metal compound in the gaseous state is obtained.

8. A silicon-carbon composite material, characterized by, The method for preparing the silicon-carbon composite material by using the liquid silane as claimed in any one of claims 1-7 is obtained.

9. Use of a silicon-carbon composite material according to claim 8, characterized in that, The silicon-carbon composite material is used as the active material raw material for preparing the battery pole piece.

10. Use of a silicon-carbon composite material according to claim 9, characterized in that, The silicon-carbon composite material is used as the active material raw material for the lithium ion battery negative pole piece.

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