Porous carbon, and silicon-carbon negative electrode material and preparation method therefor and use thereof

Abstract

The present disclosure relates to the technical field of batteries, and particularly relates to a porous carbon, and a silicon-carbon negative electrode material and a preparation method therefor and the use thereof. Provided in the present disclosure is a porous carbon. The porous carbon comprises micropores, wherein the percentage of the pore volume of the micropores in the total pore volume is greater than or equal to 85%. In a pore size distribution curve obtained by nitrogen adsorption measurements and plotted with pore size as the abscissa and differential pore volume dV / dW as the ordinate, the pore size of the porous carbon is in the range of 1-2 nm, and the differential pore volume dV / dW thereof is greater than 0.05 cm3·g-1·nm-1. The porous carbon of the present disclosure has a suitable micro-porosity and a wavy pore size distribution; therefore, the loading efficiency of silicon can be effectively improved, a space is reserved for a volume increase caused by the expansion of silicon during the cycling process of nano-scale silicon, the effect of relieving the volume expansion of silicon during lithium intercalation is achieved, the volume expansion ratio of a silicon-based negative electrode material can be reduced, and the cycling stability of a battery can be improved.

Description

Porous carbon, silicon-carbon negative electrode material and preparation method and application thereof

[0001] Cross-reference to Related Applications

[0002] The present application claims priority to the Chinese patent application No. 2024113811554, filed on September 30, 2024, and entitled "Porous carbon, silicon-carbon negative electrode material and preparation method and application thereof", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of batteries, in particular, to a porous carbon, silicon-carbon negative electrode material and a preparation method and application thereof. BACKGROUND

[0004] With the rapid development of electric vehicles, the demand for batteries is increasing. The battery usually contains a positive electrode sheet, a negative electrode sheet and a separator. The negative electrode material in the negative electrode sheet has an important influence on the electrical performance of the entire battery. Silicon-carbon negative electrode material is a new type of negative electrode material developed in recent years. Silicon negative electrode material has a huge volume change during the charging and discharging process of the battery, which can cause the shedding and pulverization of the electrode active material, and even cause damage to the electrode structure, leading to rapid capacity decay of the battery, which seriously restricts its industrial application. People usually composite carbon material and silicon material to obtain silicon-carbon composite material to achieve the purpose of improving the volume effect of silicon and improving the electrochemical stability. However, the current silicon-carbon negative electrode material still has the technical problems of unsatisfactory capacity and unsatisfactory improvement of the volume effect of silicon.

[0005] In view of this, the present disclosure is proposed.

[0006] SUMMARY

[0007] A first object of the present disclosure is to provide a porous carbon having a higher microporosity, and a pore size distribution in the range of 1-2 nm in the form of a luan distribution, which can effectively improve the loading efficiency of silicon, effectively alleviate the volume expansion of silicon during lithium intercalation, reduce the volume expansion rate of silicon-based negative electrode material, and improve its capacity and initial efficiency.

[0008] Another object of the present disclosure is to provide a silicon-carbon negative electrode material having the characteristics of high capacity and high initial efficiency, and low volume expansion rate.

[0009] Another object of the present disclosure is to provide a preparation method of a silicon-carbon negative electrode material, which is simple and easy to implement.

[0010] Another object of the present disclosure is to provide an electrode.

[0011] Another object of the present disclosure is to provide a lithium ion battery.

[0012] Another object of the present disclosure is to provide an electric appliance.

[0013] In order to achieve the above object of the present disclosure, the following technical solutions are adopted:

[0014] A porous carbon, the porous carbon comprising micropores, and a percentage of a pore volume of the micropores to a total pore volume being greater than or equal to 85%, in a pore distribution curve with a pore diameter as an abscissa and a differential pore volume dV / dW as an ordinate obtained by a nitrogen adsorption method, the porous carbon having a differential pore volume dV / dW > 0.05 cm 3 ·g -1 ·nm -1 .

[0015] In some embodiments, the porous carbon has at least one peak in the interval of the pore diameter of 1-2 nm.

[0016] In some embodiments, the porous carbon has at least one peak valley in the interval of the pore diameter of 1-2 nm, and a differential pore volume dV / dW corresponding to a lowest point of the peak valley is greater than 0.1 cm 3 ·g -1 ·nm -1 .

[0017] In some embodiments, the porous carbon has a percentage of a pore volume of pores with a pore diameter less than 0.7 nm to the total pore volume less than 30%.

[0018] In some embodiments, the porous carbon has a pore volume of 0.7-1.2 cm 3 / g.

[0019] In some embodiments, the porous carbon has a specific surface area of 1500-2500 m 2 / g.

[0020] In some embodiments, the porous carbon has a particle size Dv50 of 3-10 μm, a particle size Dv99 of 10-25 μm, and a particle size Dn10 of 0.5-5 μm.

[0021] In some embodiments, the porous carbon has a tap density of 0.3-0.5 g / cm 3 .

[0022] In some embodiments, the porous carbon has a powder conductivity of 0.5-10 S / mm.

[0023] In some embodiments, the porous carbon has a mass content of element oxygen less than 2%.

[0024] A silicon-carbon negative electrode material, comprising the porous carbon and nano-silicon in the pores of the porous carbon.

[0025] In some embodiments, the mass content of the nano-silicon in the silicon-carbon negative electrode material is 5-85%.

[0026] In some embodiments, the particle size Dv50 of the silicon-carbon negative electrode material is 3-10 μm, the particle size Dv99 of the silicon-carbon negative electrode material is 10-25 μm, and the particle size Dn10 of the silicon-carbon negative electrode material is 0.5-5 μm.

[0027] In some embodiments, the specific surface area of the silicon-carbon negative electrode material is 0.5-30 m 2 / g.

[0028] In some embodiments, the tap density of the silicon-carbon negative electrode material is 0.5-2 g / cm 3 .

[0029] In some embodiments, the surface of the silicon-carbon negative electrode material further comprises a coating layer; the coating layer comprises at least one of amorphous carbon, fast ion conductor and high molecular polymer.

[0030] A preparation method of the silicon-carbon negative electrode material as described above, comprising the following steps:

[0031] Carrying out vapor deposition of the porous carbon in an atmosphere containing a silicon source to obtain the silicon-carbon negative electrode material.

[0032] In some embodiments, further comprising: carrying out coating treatment on the silicon-carbon negative electrode material to obtain a coating layer on the surface of the silicon-carbon negative electrode material, the coating layer comprising at least one of amorphous carbon, fast ion conductor and high molecular polymer.

[0033] An electrode comprising the porous carbon, or the silicon-carbon negative electrode material, or the silicon-carbon negative electrode material prepared by the preparation method.

[0034] A lithium ion battery comprising the electrode.

[0035] An electric appliance comprising the lithium ion battery. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the specific embodiments of the present disclosure or the technical solutions in the prior art, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present disclosure, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0037] Fig. 1 is a graph of the pore size distribution of the porous carbon in Example 1 of the present disclosure (the primary ordinate axis is differential pore volume dV / dW, and the secondary ordinate axis is cumulative pore volume), and is a log-type pore;

[0038] Fig. 2 is a graph of the pore size distribution of the porous carbon in Example 2 of the present disclosure (the primary ordinate axis is differential pore volume dV / dW, and the secondary ordinate axis is cumulative pore volume), and is a log-type pore;

[0039] Fig. 3 is a graph of the pore size distribution of the porous carbon in Example 3 of the present disclosure (the primary ordinate axis is differential pore volume dV / dW, and the secondary ordinate axis is cumulative pore volume), and is a log-type pore;

[0040] Fig. 4 is a graph of the pore size distribution of the porous carbon in Comparative Example 1 of the present disclosure (the primary ordinate axis is differential pore volume dV / dW, and the secondary ordinate axis is cumulative pore volume), and is a peak-type pore;

[0041] Fig. 5 is a graph of the pore size distribution of the porous carbon in Comparative Example 2 of the present disclosure (the primary ordinate axis is differential pore volume dV / dW, and the secondary ordinate axis is cumulative pore volume), and is a log-type pore;

[0042] Fig. 6 is a graph of the pore size distribution of the porous carbon in Comparative Example 3 of the present disclosure (the primary ordinate axis is differential pore volume dV / dW, and the secondary ordinate axis is cumulative pore volume), and is a log-type pore;

[0043] Fig. 7 is a schematic view of a log-type distribution;

[0044] Fig. 8 is a schematic view of a peak-type distribution. DETAILED DESCRIPTION

[0045] The embodiments of the present disclosure will be described in detail below with reference to examples, but those skilled in the art will understand that the following examples are for illustration only and should not be construed as limiting the scope of the present disclosure. When specific conditions are not specified in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer. When the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be obtained commercially.

[0046] According to one aspect of the present disclosure, the present disclosure relates to a porous carbon including micropores, the percentage of the pore volume of the micropores to the total pore volume being greater than or equal to 85%, and in a pore distribution curve in which the abscissa is the pore diameter and the ordinate is the differential pore volume dV / dW obtained by nitrogen adsorption method, the porous carbon has a differential pore volume dV / dW > 0.05 cm 3 ·g -1 ·nm -1 .

[0047] That is, the pore distribution curve has no intersection with the abscissa axis (the pore distribution curve has no intersection with the abscissa axis means that the differential pore volume dV / dW≠0) in the range of 1-2 nm (not including the end value) and the pore distribution curve is not close to the abscissa axis (the pore distribution curve is close to the abscissa axis means that the differential pore volume dV / dW≤0.05 cm 3 ·g -1 ·nm -1 ).

[0048] In the present disclosure, according to the definition of the International Union of Pure and Applied Chemistry (IUPAC), micropore refers to a pore with a pore size less than 2 nm.

[0049] Without being bound by theory, the serious volume effect of silicon in the charging and discharging process and other basic problems seriously hinder the effective play of its advantages. In the porous carbon of the present disclosure, the percentage of the pore volume of the pores with a pore size less than 2 nm (micropores) in the total pore volume (i.e., the micropore rate) is large, which can effectively improve the silicon loading efficiency, reserve a part of space for the nanoscale silicon cycle process to alleviate the volume expansion caused by the expansion of silicon, has the effect of relieving the volume expansion of silicon when lithium is inserted, can reduce the volume expansion rate of the silicon-based negative electrode material, and improve the cycle stability of the battery.

[0050] Without being bound by theory, the pores with a pore size in the range of 1-2 nm (not including the end value) have two types of pore distribution, one is peak type distribution, and the other is stack type distribution.

[0051] Among them, the peak type pore structure mainly appears in the range of 1-2 nm (not including the end value), the pore distribution curve has more than one intersection with the abscissa axis or is close to the abscissa axis, and further, in most cases, the peak type pore structure has at least one peak in the range of 1-2 nm, and / or the porous carbon has at least one peak valley in the range of 1-2 nm, and the lowest point of the peak valley Dv / Dw<0.05 cm 3 ·g -1 ·nm -1 ; the peak type pore distribution is mainly characterized by the fact that as the pore size increases, the pore distribution changes in a peak valley type, and the transition of the pore size is relatively steep. In the peak type pore structure, the pore size distribution is discontinuous, and the total pore number is insufficient. As shown in FIG. 8, the peak type pore will have a sudden change in diameter, and when the pore is deep and the pore diameter is small, the nanosilicon will have a larger resistance to overcome, and the relative distance that can diffuse (compared with the pore depth) is shorter, and therefore, the utilization rate of the pore is also lower.

[0052] The characteristics of the distribution of the Luang-type pores mainly lie in that as the pore size increases, the pore distribution changes in a mountainous manner, the pore size transition is relatively smooth and gentle, and in the interval of 1-2 nm, the pore distribution curve has no intersection with the abscissa axis, and is not close to the abscissa axis, and the pore distribution is relatively uniform. The pore size distribution of the Luang-type structure is continuous and uninterrupted, the total number of pores is relatively large, and the pore depth is basically uniform. As shown in FIG. 7, the Luang-type pore depth does not suddenly change like the peak-type pore, so that the local resistance generated by the change in diameter can be reduced, which is conducive to the entry of the gas-phase silicon deposition precursor molecules (such as silane molecules) and improves the silicon loading efficiency. The porous carbon with the above characteristics is conducive to making the silicon-carbon have higher capacity and efficiency, and lower expansion performance.

[0053] In some embodiments, on the pore size distribution curve of the porous carbon, there is at least one peak corresponding to the interval of 1-2 nm; and / or, the porous carbon has at least one peak valley in the interval of 1-2 nm, and the differential pore volume dV / dW corresponding to the lowest point of the peak valley is greater than 0.1 cm 3 ·g -1 ·nm -1 , including but not limited to 0.11 cm 3 ·g -1 ·nm -1 , 0.12 cm 3 ·g -1 ·nm -1 , 0.15 cm 3 ·g -1 ·nm -1 , 0.2 cm 3 ·g -1 ·nm -1 , 0.5 cm 3 ·g -1 ·nm -1 , etc., or a range value between any two of the above.

[0054] In some embodiments, in the porous carbon, the percentage of the pore volume of the pores with a pore size less than 0.7 nm accounts for less than 30% of the total pore volume. In some embodiments, the percentage of the pores with a pore size less than 0.7 nm of the porous carbon includes but is not limited to 1%, 2%, 5%, 8%, 10%, 15%, 20%, 25%, 28%, 29%, etc., or a range value between any two of the above. The ultra-micropores with a pore size below 0.7 nm are difficult for silane molecules to enter during deposition, so the percentage of the ultra-micropores needs to be limited. The percentage of the pores with a pore size less than 0.7 nm of the porous carbon of the present disclosure is less than 30%, which is more conducive to ensuring the silicon loading efficiency of the porous carbon, so as to facilitate the performance of the silicon-carbon material.

[0055] In some embodiments, the pore volume of the porous carbon is greater than 0.7 cm 3 / g. In some embodiments, the pore volume of the porous carbon includes, but is not limited to, 0.72 cm 3 / g, 0.75 cm 3 / g, 0.8 cm 3 / g, 0.85 cm 3 / g, 0.9 cm 3 / g, 1 cm 3 / g, or a range between any two of the above. In some embodiments, the pore volume of the porous carbon is 0.7-1.0 cm 3 / g. The pore volume of the porous carbon of the present disclosure is appropriate, which is conducive to ensuring its physicochemical properties and facilitating the subsequent loading of silicon material, so as to ensure that it has an appropriate silicon loading rate, thereby improving the capacity and initial efficiency of the silicon-carbon composite material.

[0056] In some embodiments, the specific surface area of the porous carbon is 1500-2500 m 2 / g. In some embodiments, the specific surface area of the porous carbon includes, but is not limited to, 1500 m 2 / g, 1600 m 2 / g, 1700 m 2 / g, 1800 m 2 / g, 1900 m 2 / g, 2000 m 2 / g, 2100 m 2 / g, 2200 m 2 / g, 2500 m 2 / g, or a range between any two of the above. The porous carbon of the present disclosure has an appropriate specific surface area, which is conducive to ensuring the loading effect of the silicon material.

[0057] In some embodiments, the porous carbon of the present disclosure has an appropriate particle size, the particle size Dv50 of the porous carbon is 3-10 μm, including but not limited to 3 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a range between any two of the above. The particle size Dv99 of the porous carbon is 10-25 μm, including but not limited to 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, or a range between any two of the above. The particle size Dn10 of the porous carbon is 0.5-5 μm, including but not limited to 0.5 μm, 1 μm, 2 μm, 5 μm, or a range between any two of the above.

[0058] In some embodiments, the porous carbon of the present disclosure has an appropriate tap density, the tap density is 0.3-0.5 g / cm 3 . In some embodiments, the tap density of the porous carbon includes, but is not limited to, 0.32 g / cm 3 , 0.33 g / cm3 0.35 g / cm 3 0.38 g / cm 3 etc., or a range between any two of the above.

[0059] In some embodiments, the powder conductivity of the porous carbon of the present disclosure is 0.5-10 S / mm. In some embodiments, the powder conductivity of the porous carbon includes, but is not limited to, 2.2 S / mm, 2.5 S / mm, 2.8 S / mm, 3 S / mm, 3.5 S / mm, 4 S / mm, 5 S / mm, 8 S / mm, 10 S / mm, etc., or a range between any two of the above. The porous carbon of the present disclosure has a relatively high conductivity.

[0060] In some embodiments, the mass content of elemental oxygen in the porous carbon is less than 2%, including but not limited to 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, etc., or a range between any two of the above.

[0061] In some embodiments of the present disclosure, the porous carbon includes at least one of biomass-derived carbon, resin-derived carbon, petroleum coke-derived carbon, coal-derived carbon, metal-modified carbon material, and metal oxide-modified carbon material.

[0062] In some embodiments of the present disclosure, the preparation method of the porous carbon is described below by way of example, but is not limited thereto.

[0063] The preparation method of the porous carbon includes the following steps:

[0064] (1) Dry the mangosteen peel and grind it into powder.

[0065] (2) Stir the powder obtained in step (1) in HCl, and then wash it with deionized water until the water is colorless, and dry it.

[0066] (3) Disperse the dried mangosteen peel powder obtained in step (2) and KOH in water at a mass ratio of 1:1-1:4, stir, and then freeze-dry to remove water.

[0067] (4) In an argon atmosphere, rapidly heat the mixed precursor obtained in step (3) to 200°C in a tube furnace, then slowly heat it from 200°C to 550°C, and then rapidly heat it to 600-1000°C, and heat it at 600-1000°C for 1 h.

[0068] (5) Wash the calcined product with deionized water, and vacuum dry it to obtain the porous carbon.

[0069] In some embodiments of the present disclosure, in step (4), the mixed precursor obtained in step (3) is rapidly heated to 200°C at a heating rate of 10°C / min in a tube furnace under an argon atmosphere, then slowly heated from 200°C to 550°C at a heating rate of 10°C / min, and heated at 550°C for 10h, and then rapidly heated to 600-1000°C at a heating rate of 10°C / min, and heated at 600-1000°C for 1h.

[0070] In some embodiments of the present disclosure, step (5) further comprises a process of sieving after vacuum drying.

[0071] In some embodiments of the present disclosure, the particle size distribution of the porous carbon can be controlled by the process of grinding into powder in step (1) and / or the process of sieving after vacuum drying in step (5). This is well known in the art and will not be repeated here.

[0072] According to another aspect of the present disclosure, the present disclosure relates to a silicon-carbon negative electrode material, comprising the porous carbon and nano-silicon located in the pores of the porous carbon.

[0073] In the present disclosure, the nano-silicon is a silicon material with at least one dimension less than 100nm. For example, the nano-silicon has at least one dimension of 99nm, 90nm, 80nm, 70nm, 60nm, 50nm, 40nm, 30nm, 20nm, 10nm, 9nm, 8nm, 7nm, 6nm, 5nm, 4nm, 3nm, 2nm, 1.5nm, 1nm, 0.5nm, 0.1nm, 0.01nm, etc., or other values within the range.

[0074] In some embodiments of the present disclosure, the nano-silicon can be nano-silicon particles, and the crystalline domain size of the nano-silicon particles is 0nm-3nm, specifically, 0.01nm, 0.1nm, 0.5nm, 1nm, 1nm, 3nm, or any value between 0nm and 3nm. Small particles have higher specific surface area and shorter diffusion path, can release pressure faster, and reduce the degree of volume expansion, which is beneficial to the improvement of coulombic efficiency. For example, the typical but non-limiting range can be nano-silicon particles with a particle size of 1-3nm.

[0075] The present disclosure uses the above-mentioned porous carbon as a carrier to load nano-silicon, which can effectively improve the loading efficiency of nano-silicon, and can reserve a part of space for the volume expansion of silicon caused by the expansion of nano-silicon during the cycling process, which has the effect of relieving the volume expansion of silicon during lithium intercalation, and can reduce the volume expansion rate of the silicon-based negative electrode material. The silicon-carbon negative electrode material of the present disclosure has the characteristics of high capacity and high initial efficiency, and improves the cycle stability of the battery.

[0076] In some embodiments, the mass content of the nanosilicon in the silicon-carbon negative electrode material is 5% to 85%, including but not limited to 5%, 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 80%, 85%, or a range value between any two of the above. In the silicon-carbon negative electrode material of the present disclosure, the nanosilicon has a suitable mass content, which is more conducive to ensuring the comprehensive electrical performance of the silicon-carbon negative electrode material.

[0077] In some embodiments, the particle size Dv50 of the silicon-carbon negative electrode material of the present disclosure is 3 to 10 μm, including but not limited to 3 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a range value between any two of the above. The particle size Dv99 of the silicon-carbon negative electrode material is 10 to 25 μm, including but not limited to 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, or a range value between any two of the above. The particle size Dn10 of the silicon-carbon negative electrode material is 0.5 to 5 μm, including but not limited to 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or a range value between any two of the above. The silicon-carbon negative electrode material of the present disclosure has the above suitable particle size, which is more conducive to ensuring the performance of the slurry and improving the volume energy, charge-discharge performance, and cycle performance of the battery.

[0078] In some embodiments, the silicon-carbon negative electrode material of the present disclosure has a suitable specific surface area, and the specific surface area is 0.5 to 30 m 2 / g. In some embodiments, the specific surface area of the silicon-carbon negative electrode material includes but is not limited to 0.5 m 2 / g, 1 m 2 / g, 3 m 2 / g, 5 m 2 / g, 10 m 2 / g, 15 m 2 / g, 30 m 2 / g, or a range value between any two of the above.

[0079] In some embodiments, the tap density of the silicon-carbon negative electrode material of the present disclosure is 0.5 to 2 g / cm 3 . In some embodiments, the tap density of the silicon-carbon negative electrode material includes but is not limited to 0.5 g / cm 3 , 0.72 g / cm 3 , 0.75 g / cm 3 , 0.78 g / cm 3 , 0.8 g / cm 3 , 0.85 g / cm 3 , 0.9 g / cm 3or a range value between any two of the above. The silicon-carbon negative electrode material of the present disclosure has a suitable tap density, which is conducive to obtaining high capacity and high initial efficiency.

[0080] In some embodiments, the surface of the silicon-carbon negative electrode material of the present disclosure further comprises a coating layer; the coating layer comprises at least one of amorphous carbon, fast ion conductor and high molecular polymer, which is more conducive to improving the comprehensive electrical performance of the negative electrode material.

[0081] According to another aspect of the present disclosure, the present disclosure also relates to a preparation method of the silicon-carbon negative electrode material as above, comprising the following steps:

[0082] The porous carbon is subjected to vapor deposition in an atmosphere containing a silicon source to obtain the silicon-carbon negative electrode material.

[0083] The preparation method of the silicon-carbon negative electrode material of the present disclosure is simple and easy to implement, and the silicon-carbon negative electrode material can be obtained by vapor deposition of a silicon source on porous carbon. The silicon-carbon negative electrode material obtained by the method has the characteristics of high capacity and high initial efficiency.

[0084] In some embodiments, the temperature of the vapor deposition is 300-1200℃, including but not limited to 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, etc., or a range value between any two of the above.

[0085] In some embodiments, the silicon source of the present disclosure comprises at least one of monosilane (SiH4), propylsilane, disilane, dimethylsilane, dichlorodisilane, hexamethyldisilane, silicon tetrachloride, trichlorosilane, silicon tetrafluoride.

[0086] In some embodiments, the method further comprises: coating the silicon-carbon negative electrode material to obtain a coating layer on the surface of the silicon-carbon negative electrode material, the coating layer comprising at least one of amorphous carbon, fast ion conductor and high molecular polymer. The present disclosure further coats a carbon coating layer to improve the electrical performance of the silicon-carbon negative electrode material.

[0087] In some embodiments, the temperature of the coating treatment is 300-1200℃, including but not limited to 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, or any range between any two of the above values. The deposition time of the coating treatment is 20 min-6 h, including but not limited to 20 min, 1 h, 2 h, 3 h, 4 h, 5 h, or 6 h, or any range between any two of the above values. By using suitable coating treatment conditions, the present disclosure is more conducive to obtaining a uniform and high-quality carbon coating layer, and is conducive to the performance of the final negative electrode material.

[0088] In some specific embodiments, the method for preparing the silicon-carbon negative electrode material comprises the following steps:

[0089] (a) Dry the mangosteen peel and grind it into powder; stir the powder in HCl, then wash it with deionized water until the water is colorless, and dry it; uniformly disperse the dried mangosteen peel powder and KOH in water at a mass ratio of 1:1-1:4, stir, then freeze-dry to remove water, to obtain a mixed precursor; in an argon atmosphere, rapidly heat the obtained mixed precursor in a tube furnace to 200℃ at a rate of 10℃ / min, then slowly heat it from 200℃ to 550℃, with a heating time of 10 h, then rapidly heat it to 600-1000℃ at a heating rate of 10℃ / min, and heat it at 600-1000℃ for 1 h, to obtain a calcined product; wash the calcined product with deionized water, then vacuum dry and sieve it, to obtain porous carbon.

[0090] (b) Place the porous carbon of step (a) in a heat treatment device, and perform preheating treatment, with a preheating temperature of 90-120℃, and a vacuum state for 20-40 min; then introduce a protective gas, then heat it to 300-1200℃ at a rate of 1-8℃ / min, then introduce a silicon source gas at a flow rate of 0.4-12 L / min, for 2-5 h, then close the silicon source valve, to obtain a first material.

[0091] (c) Heat the obtained first material to 300-1200℃, introduce a carbon source gas, for 20 min-6 h, to obtain a silicon-carbon negative electrode material.

[0092] According to another aspect of the present disclosure, the present disclosure also relates to an electrode comprising the porous carbon, or the silicon-carbon negative electrode material, or the silicon-carbon negative electrode material prepared by the method described above.

[0093] The electrode of the present disclosure comprises the above-described porous carbon, and has excellent electrical performance. The electrode comprises a current collector and a negative electrode material layer on the surface of the current collector, and the negative electrode material layer comprises the above-described porous carbon or silicon-carbon negative electrode material.

[0094] According to another aspect of the present disclosure, the present disclosure also relates to a lithium ion battery comprising the electrode.

[0095] The lithium ion battery of the present disclosure has high capacity, high initial efficiency, excellent cycle performance and safety performance.

[0096] According to another aspect of the present disclosure, the present disclosure also relates to an electric appliance comprising the lithium ion battery.

[0097] In the present disclosure, the electric appliance can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc.

[0098] The present disclosure will be further explained in conjunction with specific examples and comparative examples.

[0099] Example 1

[0100] A preparation method of a silicon-carbon negative electrode material, comprising the following steps:

[0101] S1. Preparation of porous carbon:

[0102] (1) Dry the mangosteen skin at 80℃ for 24h, and grind into powder.

[0103] (2) Stir in 1M HCl overnight, then wash with deionized water until the water is colorless, and dry at 80℃ for 12h.

[0104] (3) Disperse the dried mangosteen skin powder and KOH in water at a mass ratio of 1:3, stir overnight, and then freeze-dry to remove water.

[0105] (4) In an argon atmosphere, heat the mixed precursor in a tube furnace at a heating rate of 10℃ / min to 200℃, then from 200℃ to 550℃, the heating time is 10h, then heat at a rate of 10℃ / min to 780℃, and heat at 780℃ for 1h.

[0106] (5) Finally, wash the calcined product with deionized water, vacuum dry at 80℃ for 12h, and sieve to obtain the porous carbon.

[0107] The particle size D50 of the porous carbon in this example is 7.6μm, the Dv99 is 22.7μm, the Dn10 is 3.1μm, the specific surface area is 1946m 2 / g, the pore volume is 0.91cm 3 / g, the electrical conductivity is 2.7S / mm, and the pore structure is that the pore volume of pores less than 2nm accounts for 94% of the total pore volume (microporosity), the pore volume of pores less than 0.7nm accounts for 25% of the total pore volume (microporosity), and the pore size distribution is a luan type distribution.

[0108] S2. Vapor-phase silicon deposition: The porous carbon was placed in a rotary furnace, heated to 100℃, and vacuumized for 30 min, then nitrogen was introduced for protection, and then heated to 550℃ at a rate of 5℃ / min, and then silane was introduced at a flow rate of 10 L / min, and the introduction time was 4 h, and after the reaction was completed, the silicon source valve was closed;

[0109] S3. Carbon coating: After the silicon deposition was completed, the temperature was increased to 700℃, and acetylene was introduced at a flow rate of 5 L / min, and the introduction time of acetylene was 3 h, and the silicon-carbon negative electrode material was obtained.

[0110] Example 2

[0111] The preparation method of the negative electrode material provided in this example refers to Example 1, except that:

[0112] S1. Preparation of porous carbon:

[0113] (1) The mangosteen skin was dried at 80℃ for 24 h, and then ground into powder.

[0114] (2) Stirred in 1M HCl overnight, then washed with deionized water until the water was colorless, and dried at 80℃ for 12 h.

[0115] (3) The dried mangosteen skin powder and KOH were uniformly dispersed in water at a mass ratio of 1:2, stirred overnight, and then freeze-dried to remove water.

[0116] (4) In an argon atmosphere, the mixed precursor was heated in a tube furnace at a heating rate of 10℃ / min to 200℃, and then heated from 200℃ to 550℃, and the heating time was 10 h, and then heated to 650℃ at a heating rate of 10℃ / min, and heated at 650℃ for 1 h.

[0117] (5) Finally, the calcined product was washed with deionized water, vacuum dried at 80℃ for 12 h, and sieved to obtain the porous carbon.

[0118] The particle size D50 of the porous carbon in this example was 7.3μm, the Dv99 was 21.1μm, the Dn10 was 0.5μm, the specific surface area was 1669m 2 / g, the pore volume was 0.74cm 3 / g, the electrical conductivity was 1.9S / mm, the pore structure was that the pore volume of pores less than 2nm accounted for 93% of the total pore volume (microporosity), the pore volume of pores less than 0.7nm accounted for 28% of the total pore volume (microporosity), and the pore size distribution was a luan-type distribution.

[0119] Example 3

[0120] The preparation method of the negative electrode material provided in this embodiment refers to Embodiment 1, except that:

[0121] S1. Preparation of porous carbon:

[0122] (1) Dry the mangosteen peel at 80°C for 24h, and grind into powder.

[0123] (2) Stir in 1M HCl overnight, then wash with deionized water until the water is colorless, and dry at 80°C for 12h.

[0124] (3) Disperse the dried mangosteen peel powder and KOH in water at a mass ratio of 1:2.5, stir overnight, and then freeze-dry to remove water.

[0125] (4) In an argon atmosphere, heat the mixed precursor in a tube furnace at a heating rate of 10°C / min to 200°C, then from 200°C to 550°C at a heating rate of 10°C / min for 10h, then from 550°C to 700°C at a heating rate of 10°C / min, and heat at 700°C for 1h.

[0126] (5) Finally, wash the calcined product with deionized water, vacuum dry at 80°C for 12h, and sieve to obtain the porous carbon.

[0127] The porous carbon in this embodiment has a particle size D50 of 6.4μm, a Dv99 of 18.7μm, a Dn10 of 2.5μm, a specific surface area of 1911m 2 / g, a pore volume of 0.81cm 3 / g, and a conductivity of 2.7S / mm. The pore structure is as follows: the pore volume of pores less than 2nm accounts for 100% of the total pore volume (microporosity), the pore volume of pores less than 0.7nm accounts for 29% of the total pore volume (microporosity), and the pore size distribution is a luan-type distribution.

[0128] Comparative Example 1

[0129] The difference between the preparation method of the negative electrode material in this comparative example and Embodiment 1 is that the porous carbon used for gas-phase silicon deposition is different. The porous carbon used in this comparative example is purchased from Jiangsu Pusida Environmental Protection Technology Co., Ltd., model PAC-A1, and the remaining process parameters for gas-phase silicon deposition and carbon coating are the same as in Embodiment 1.

[0130] The porous carbon in this comparative example has a particle size D50 of 7.2μm, a Dv99 of 23μm, a Dn10 of 3.5μm, a specific surface area of 1297m 2 / g, a pore volume of 0.94cm 3 / g, the pore volume of pores less than 2 nm accounted for 54% of the total pore volume, the pore volume of pores less than 0.7 nm (micropore ratio) accounted for 25% of the total pore volume, and the pore structure of the porous carbon had a peak structure.

[0131] Comparative Example 2

[0132] The difference between the preparation method of the negative electrode material in the present comparative example and that in Example 1 is that the porous carbon used for the vapor-phase silicon deposition is different. The porous carbon used in the present comparative example was purchased from Dachao Carbon Energy Co., Ltd., and the rest of the process parameters for the vapor-phase silicon deposition and carbon coating were the same as those in Example 1.

[0133] The particle size D50 of the porous carbon in the present comparative example was 7.6 μm, the Dv99 was 22 μm, the Dn10 was 0.5 μm, the specific surface area was 2053 m 2 / g, the pore volume was 0.84 cm 3 / g, the conductivity was 2.92 S / mm, the pore volume of pores less than 2 nm accounted for 100% of the total pore volume, the pore volume of pores less than 0.7 nm (micropore ratio) accounted for 33% of the total pore volume, and the pore structure of the porous carbon had a pine structure.

[0134] Comparative Example 3

[0135] The difference between the preparation method of the silicon-carbon negative electrode material in the present comparative example and that in Example 1 is that the porous carbon used for the vapor-phase silicon deposition is different. The porous carbon used in the present comparative example was purchased from Jiangsu Pusida Environmental Protection Technology Co., Ltd., and the model number was PAC-SP40, and the rest of the process parameters for the vapor-phase silicon deposition and carbon coating were the same as those in Example 1.

[0136] The particle size D50 of the porous carbon in the present comparative example was 6.6 μm, the Dv99 was 20.8 μm, the Dn10 was 3.4 μm, the specific surface area was 1282 m 2 / g, the pore volume was 0.72 cm 3 / g, the conductivity was 4.3 S / mm, the pore volume of pores less than 2 nm accounted for 50% of the total pore volume, the pore volume of pores less than 0.7 nm (micropore ratio) accounted for 21% of the total pore volume, and the pore structure of the porous carbon had a pine structure.

[0137] Experimental Example

[0138] 1. Performance test of the porous carbon

[0139] The test methods of the specific surface area, pore volume, and <2 nm pore ratio of the porous carbon in each example and comparative example are as follows:

[0140] Specific surface area and pore volume: tested according to GB / T 19587-2017. The measurements were performed using an ASAP 2460 (from Micromeritics) working according to the Sorption Method with Adaptive dosing Rate (SMART method). As reference materials, the standards GB13905 (9.01 m 2 / g based on the multipoint BET method), GB13913 (5.78 m 2 / g based on the multipoint BET method) and GB13909 (Mesoporous SiO2 Specific Surface Area, Total Pore Volume and Pore Size Standard Reference Material) can be used.

[0141] To reduce the dead volume, a filling rod was added to the reference and sample tubes. The tubes were installed on the BET apparatus. The saturated vapour pressure of nitrogen (N2 4.0) was determined. An amount of sample was weighed into a glass tube such that the tube containing the filling rod was completely filled and the smallest dead volume was created. To dry the sample, the sample was kept under vacuum at 200 °C for 2 h. After cooling, the sample weight was recorded. The glass tube containing the sample was installed on the measuring apparatus. To degas the sample, it was evacuated at the selected pumping speed such that no material was sucked into the pump, reaching a final pressure of 200 mTorr.

[0142] Micropore fraction (micropore rate) test method: the percentage of the pore volume of the pores with a pore size less than 2 nm in the total pore volume in the porous carbon was tested by nitrogen adsorption method. The nitrogen adsorption measurement was carried out at liquid nitrogen temperature (77.3 K) using an ASAP 2460 instrument of Micromeritics Company. Before measurement, the sample was degassed at 443 K until a static vacuum of less than 0.01 Torr was reached. The adsorption potential distribution was calculated according to the adsorption isotherm using the standard instrument software DFT (NLDFT) software.

[0143] The above test results of the porous carbons of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1.

[0144] Table 1 Physical parameters of porous carbons

[0145] The pore size distribution curve of the porous carbon in Example 1 of the present disclosure is shown in FIG. 1, the pore size distribution curve of the porous carbon in Example 2 is shown in FIG. 2, and the pore size distribution curve of the porous carbon in Example 3 is shown in FIG. 3. It can be seen that, in the porous carbon of the present disclosure, as the pore size increases, the pore distribution changes in a mountainous manner. In the pore size range of 1-2 nm, the pore size distribution curve has no intersection with the abscissa, and the pore transition is relatively smooth and gentle, that is, the micropore channels of the porous carbon are relatively uniform. The pore size of the porous carbon of the present disclosure is in a pine type distribution, as shown in FIG. 7, the pore size distribution is continuous and uninterrupted, the total pore number is relatively large, and the pore depth is basically uniform, which can reduce the local resistance caused by the change in diameter, is conducive to the entry of silane molecules, improves the silicon loading efficiency, and is conducive to improving the electrochemical performance of the silicon-carbon negative electrode material.

[0146] The pore size distribution curve of the porous carbon in Comparative Example 1 of the present disclosure is shown in FIG. 4. It can be seen that, in the pore size range of 1-2 nm, the pore size curve has multiple intersections with the abscissa, and as the pore size increases, the pore distribution changes in a peak-valley type manner with high peaks and low valleys, and the pore transition is relatively steep, that is, the micropore channels are not uniform, and there are significant diameter changes. The schematic diagram of the peak type pores of the porous carbon in Comparative Example 1 is shown in FIG. 8. The pore size distribution is discontinuous, and the total pore number is insufficient. When the pore is deep and the pore diameter is small, the resistance that needs to be overcome for the nanosilicon to enter is greater, and the relative distance that can diffuse (compared with the pore depth) is shorter. Therefore, the utilization rate of the pores is also lower, which is not conducive to the loading of silicon materials and the performance of the silicon-carbon negative electrode material.

[0147] The porous carbon in Comparative Example 2 of the present disclosure is purchased from Dachao Carbon Energy Co., Ltd. The pore size distribution curve of the porous carbon is shown in FIG. 5. The pore volume of the pores with a pore size less than 0.7 nm accounts for a relatively high percentage of the total pore volume.

[0148] The porous carbon in Comparative Example 3 of the present disclosure is purchased from Jiangsu Pusida Environmental Protection Technology Co., Ltd. The pore size distribution curve of the porous carbon is shown in FIG. 6. The specific surface area is relatively low, and the micropore rate is low.

[0149] 2. Performance test of silicon-carbon negative electrode material

[0150] The particle size, specific surface area, tap density, silicon content and silane utilization rate of the silicon-carbon negative electrode materials of each example and comparative example were tested, and the test methods were as follows:

[0151] Test of specific surface area: BET method was used to test the specific surface area according to GB / T 19587-2017, including: nitrogen adsorption measurement was carried out using an ASAP 2460 instrument of Micromeritics Co., Ltd. at a liquid nitrogen temperature (77.3K). Before measurement, the sample was degassed at 443K until a static vacuum of less than 0.01 torr was reached. The adsorption point distribution was calculated according to the adsorption isotherm, and the standard instrument software DFT (NLDFT) software. In order to reduce the dead volume, a packing rod was added to the reference tube and sample tube (the specific test method is the same as that of the test method of the specific surface area of the porous carbon).

[0152] Particle size test: The Malvern 3000 device was used for testing, and the test was carried out according to the national standard GB / T 19077-2016.

[0153] Tap density test: The Dandong Bitai BT313 tap density instrument was used for testing, and the test was carried out according to the national standard GB / T 24533-2019.

[0154] Silicon content test: The silicon content was tested by a thermogravimetric analyzer at 1000℃ in air for 1h, the carbon was completely oxidized and lost weight, and the silicon was completely converted into silicon dioxide, and then the weight of the added oxygen was used to calculate the silicon content in the silicon-carbon material. The specific process is as follows:

[0155] (1) About 2g of silicon-carbon material was weighed, and the actual mass was recorded as m0; and was placed in a crucible with a mass of m1;

[0156] (2) The crucible was placed in a tube furnace or a muffle furnace, and compressed air was continuously supplied, and the temperature was raised to 600℃ at a rate of 10℃ / min, and was kept for 1h, and then was raised to 1000℃ at the same rate, and was kept for 1h;

[0157] (3) After natural cooling to room temperature, the crucible was taken out, and the mass was m2;

[0158] (4) The Si content Si% was calculated as (m2-m1)×MSi÷MSiO2÷m0×100%;

[0159] Wherein, Note: MSiO2 is the relative molecular mass of SiO2 60.084g / mol; MSi is the relative molecular mass of Si 28.0855g / mol.

[0160] Silane utilization rate% = [amount of collected material (g) x silicon content (%)] / [volume of silane (L) x density of silane (g / L)].

[0161] The performance test results of the silicon-carbon negative electrode material are shown in Table 2.

[0162] Table 2 Performance test results of silicon-carbon negative electrode material

[0163] As can be seen from Table 2, the silicon-carbon negative electrode material obtained by the method of the embodiments of the present disclosure has suitable particle size, specific surface area, tap density and silicon content, and the silane utilization rate is high, reaching 93% and above. The silane utilization rate of the silicon-carbon negative electrode material obtained by Comparative Examples 1-3 is relatively low.

[0164] 3. Battery performance test results

[0165] The silicon-carbon negative electrode material of each example and comparative example was used to prepare a button-type half cell, including the following steps:

[0166] The active material, SP, CNT and PAA glue solution were mixed in a mass ratio of 80:9:1:10, and deionized water was used to prepare a slurry, which was uniformly coated on a copper foil, vacuum dried at 80°C for 24h, to prepare a battery negative electrode sheet for experiment. Lithium sheet was used as the counter electrode, 1.1 mol / L LiPF6 electrolyte was used, the solvent was a four-component mixed solvent, ethylene carbonate (EC): vinylene carbonate (VC): dimethyl carbonate (DMC): fluoroethylene carbonate (FEC) = 1:1:1:1 (volume ratio), and a polypropylene microporous membrane was used as a separator. A CR2025 button-type half cell was assembled in a vacuum glove box.

[0167] The battery performance test method was as follows: the battery test system (half cell test American Arbin multi-channel battery test system, German Braun Labstar (1200 / 780) type glove box) was used to test the capacity and the first charge-discharge efficiency (first efficiency).

[0168] The test procedure was as follows: 0.1C DC to 5mV, standing for 5min; 0.02C DC to 5mV, standing for 5min; 0.01C DC to 5mV, standing for 5min; 0.1C CC to 0.8V, 0.1C CC to 2V.

[0169] The battery performance test results are shown in Table 3.

[0170] Table 3 Battery performance test results

[0171] The pore size distribution of the porous carbon of the present disclosure is a luan-type distribution, and has a suitable microporosity, specific surface area, pore volume and particle size. The silicon-carbon negative electrode material prepared therefrom has the characteristics of high capacity, high first efficiency and low silicon expansion rate. As shown in Table 3, the obtained battery has excellent discharge capacity and efficiency, and the 1.5V discharge capacity is above 1990mAh and the 1.5V efficiency is above 90%. The silicon-carbon negative electrode material of Comparative Example 1 is prepared from porous carbon with a peak-type pore structure, and the obtained battery has low capacity and poor efficiency, with a 1.5V discharge capacity of 1680mAh and a 1.5V efficiency of 78.2%. The silicon-carbon negative electrode material and battery of Comparative Examples 2-3 are prepared using conventional porous carbon, and the capacity and efficiency of the obtained battery are lower than those of Example 1.

[0172] Compared with the prior art, the present disclosure has the following beneficial effects:

[0173] (1) The porous carbon of the present disclosure has a high microporosity, and the pore size distribution is in a luan distribution in the interval of 1-2 nm, which can effectively improve the loading efficiency of silicon, can reserve a part of space for the nano-silicon cycle process to relieve the volume expansion caused by the lithium intercalation of silicon, has the effect of relieving the volume expansion when the silicon intercalates lithium, can reduce the volume expansion rate of the silicon-based negative electrode material, and improve the capacity and initial efficiency of the silicon-carbon negative electrode material.

[0174] (2) The silicon-carbon negative electrode material of the present disclosure has the characteristics of high capacity and high initial efficiency, and can improve the cycle stability of the battery.

[0175] (3) The preparation method of the silicon-carbon negative electrode material of the present disclosure is simple and easy to operate, and the silicon-carbon negative electrode material can be obtained by vapor deposition of a silicon source on the porous carbon. The silicon-carbon negative electrode material obtained by the method has the characteristics of high capacity and high initial efficiency, and can improve the cycle performance and safety performance of the battery.

[0176] Finally, it should be pointed out that: the above embodiments are only used to illustrate the technical solutions of the present disclosure, but not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present disclosure. Industrial applicability

[0177] The porous carbon of the present disclosure can effectively improve the loading efficiency of silicon, can reserve a part of space for the nano-silicon cycle process to relieve the volume expansion caused by the lithium intercalation of silicon, has the effect of relieving the volume expansion when the silicon intercalates lithium, can reduce the volume expansion rate of the silicon-based negative electrode material, and improve the capacity and initial efficiency of the silicon-carbon negative electrode material; the silicon-carbon negative electrode material of the present disclosure has the characteristics of high capacity and high initial efficiency, and can improve the cycle stability and safety performance of the battery; the preparation method of the silicon-carbon negative electrode material of the present disclosure is simple and easy to operate, and the silicon-carbon negative electrode material can be obtained by vapor deposition of a silicon source on the porous carbon; the electrode of the silicon-carbon negative electrode material of the present disclosure comprises the above porous carbon and has excellent electrical properties; the lithium ion battery of the silicon-carbon negative electrode material electrode of the present disclosure has high capacity, high initial efficiency, excellent cycle performance and safety performance; the electric appliance of the lithium ion battery of the silicon-carbon negative electrode material electrode of the present disclosure can be, but is not limited to, mobile phones, tablets, notebook computers, electric toys, electric tools, electric vehicles, electric cars, ships, spacecraft, etc.

Claims

1. A porous carbon, characterized by, The porous carbon includes micropores, and a percentage of a pore volume of the micropores with respect to a total pore volume is greater than or equal to 85%, and in a pore distribution curve in which an abscissa is a pore diameter and an ordinate is a differential pore volume dV / dW obtained by a nitrogen adsorption method, the porous carbon has a differential pore volume dV / dW > 0.05 cm 3 ·g -1 ·nm -1 .

2. The porous carbon according to claim 1, characterized in that, comprises at least one of the following features (1) to (4): (1) the porous carbon has at least one peak in the pore size interval of 1 to 2 nm; (2) the porous carbon has at least one peak valley in the interval of 1-2 nm in pore size, and the differential pore volume dV / dW corresponding to the lowest point of the peak valley is >0.1 cm 3 · g -1 · nm -1 ; (3) in the porous carbon, the percentage of pore volume of pores with a pore size less than 0.7 nm accounts for less than 30% of the total pore volume; (4) the porous carbon has a pore volume of 0.7 to 1.2 cm3 / g 3 / g.

3. The porous carbon according to claim 1 or 2, characterized in that, comprises at least one of the following features (1) to (5): (1) the specific surface area of the porous carbon is 1500 to 2500 m2 / g 2 / g; (2) the particle size Dv50 of the porous carbon is 3 to 10 μm, the particle size Dv99 of the porous carbon is 10 to 25 μm, and the particle size Dn10 of the porous carbon is 0.5 to 5 μm; (3) the tap density of the porous carbon is 0.3 to 0.5 g / cm3 3 ; (4) the powder conductivity of the porous carbon is 0.5 to 10 S / mm; (5) in the porous carbon, the mass content of element oxygen is less than 2%.

4. A silicon-carbon negative electrode material, characterized by, The silicon-carbon negative electrode material comprises the porous carbon according to any one of claims 1 to 3 and nano-silicon in the pores of the porous carbon.

5. The silicon-carbon negative electrode material of claim 4, wherein, comprises at least one of the following features (1) to (5): (1) the mass content of the nano-silicon in the silicon-carbon negative electrode material is 5 to 85%; (2) the particle size Dv50 of the silicon-carbon negative electrode material is 3 to 10 μm, the particle size Dv99 of the silicon-carbon negative electrode material is 10 to 25 μm, and the particle size Dn10 of the silicon-carbon negative electrode material is 0.5 to 5 μm; (3) the specific surface area of the silicon-carbon negative electrode material is 0.5-30 m 2 / g; (4) the silicon-carbon negative electrode material has a tap density of 0.5-2 g / cm 3 ; (5) the surface of the silicon-carbon negative electrode material further comprises a coating layer; the coating layer comprises at least one of amorphous carbon, fast ion conductor and high molecular polymer.

6. The method for preparing a silicon-carbon negative electrode material according to claim 4 or 5, characterized in that, comprises the following steps: carrying out vapor deposition of the porous carbon in an atmosphere containing a silicon source to obtain the silicon-carbon negative electrode material.

7. The method of producing a silicon-carbon negative electrode material according to claim 6, characterized by, further comprises: carrying out coating treatment on the silicon-carbon negative electrode material to obtain a coating layer on the surface of the silicon-carbon negative electrode material, the coating layer comprising at least one of amorphous carbon, fast ion conductor and high molecular polymer.

8. An electrode characterized by, comprises the porous carbon according to any one of claims 1 to 3, or the silicon-carbon negative electrode material according to any one of claims 4 to 5, or the silicon-carbon negative electrode material prepared by the preparation method according to any one of claims 6 to 7.

9. A lithium-ion battery, characterized by comprises the electrode according to claim 8.

10. An electric appliance characterized by comprising: comprises the lithium ion battery according to claim 9.

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