A resin porous silicon-carbon anode material, its preparation method and a lithium-ion battery

Abstract

The present invention provides a resin porous silicon-carbon anode material, a preparation method thereof and a lithium-ion battery, relating to the technical field of lithium-ion batteries; the preparation method comprises the following steps: heating the pulverized hardened resin to 600-900 °C to realize resin porosification, obtaining an intermediate product I; in a closed environment, introducing silane gas into the intermediate product I and heating to 400-500 °C to cause silane cracking to form an intermediate product II; mixing the intermediate product II with the hardened resin to obtain a resin porous silicon-carbon precursor; heating the resin porous silicon-carbon precursor to 1000-1500 °C to obtain the resin porous silicon-carbon anode material. The present invention uses resin as a raw material to prepare resin porous carbon, and then uses silane gas as a silicon source to introduce silicon elements into the resin porous carbon by means of silane cracking, which helps to avoid the agglomeration of silicon elements and improve the uniformity of silicon element distribution, and helps to improve the cycle performance while increasing the specific capacity of the anode material.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly relates to a resin porous silicon-carbon negative electrode material, a preparation method thereof, and a lithium-ion battery. Background Art

[0002] The most widely used negative electrode material for lithium-ion batteries is graphite-based negative electrode material. Currently, the specific capacity of commercialized graphite materials is generally about 340 mAh / g. The process cost of graphite-based materials is mainly reflected in the graphitization stage. Due to the high graphitization temperature, the energy consumption is large and the production cost is high.

[0003] Among the negative electrode materials for lithium ions, in addition to graphite-based materials, silicon materials have received wide attention due to their high theoretical capacity. However, due to the poor conductivity of silicon materials themselves and the large volume expansion during charge and discharge, the cycle performance is poor, which limits the application of silicon materials in negative electrode materials for lithium-ion batteries. To solve this problem, currently, nano-silicon is usually used to prepare silicon-carbon composite materials to improve the conductivity of the composite materials while suppressing the volume expansion of the materials during charge and discharge to a certain extent and improving their cycle performance.

[0004] Existing silicon-carbon negative electrode materials are usually directly prepared by mixing and sintering a silicon source and a carbon source. Although the silicon-carbon composite negative electrode materials obtained by this preparation method have a high specific capacity, due to the easy agglomeration of nano-silicon and poor dispersion during the preparation process, the distribution of silicon elements in the prepared silicon-carbon negative electrode materials is uneven, and the cycle performance is still poor. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to solve the problem of poor uniformity of silicon element distribution in the silicon-carbon negative electrode materials prepared in the prior art, the present invention provides a preparation method of a resin porous silicon-carbon negative electrode material. This preparation method introduces silicon elements into the negative electrode material through silane cracking to improve the dispersion of silicon elements and solves the problem of poor uniformity of silicon element distribution in the silicon-carbon negative electrode materials prepared in the prior art.

[0006] The technical solution adopted by the present invention to solve its technical problems is:

[0007] A preparation method of a resin porous silicon-carbon negative electrode material includes the following steps:

[0008] S1: Hardening the resin to obtain a hardened resin;

[0009] S2: Crushing the hardened resin to obtain the crushed hardened resin;

[0010] S3: Heating the crushed hardened resin to 600 - 900 °C in an air atmosphere and holding for 5 h to achieve resin porousization, obtaining intermediate product I;

[0011] S4: In a closed environment, introduce silane gas into the intermediate product I, heat up to 400 - 500 °C, and keep the temperature for 60 - 150 min to pyrolyze the silane and form intermediate product II;

[0012] S5: Mix the intermediate product II with the cured resin and grind to obtain a resin porous silicon carbon precursor;

[0013] S6: Under an air atmosphere, heat the resin porous silicon carbon precursor to 1000 - 1500 °C and keep the temperature for 5 h to obtain a resin porous silicon carbon negative electrode material.

[0014] Optionally, the resin is a thermosetting resin.

[0015] Optionally, the resin is a phenolic resin or an epoxy resin.

[0016] Optionally, curing the resin includes: heating the resin to 150 - 250 °C and keeping the temperature for 6 - 15 h to obtain the cured resin.

[0017] Optionally, the silane is selected from at least one of monosilane and disilane.

[0018] Optionally, in step S4, the dosage ratio of the intermediate product I to the silane gas is (45 - 50) g : 7 L.

[0019] Optionally, in step S5, the mass ratio of the intermediate product II to the cured resin is (5 - 10) : 1.

[0020] Another object of the present invention is to provide a resin porous silicon carbon negative electrode material prepared by the preparation method of the resin porous silicon carbon negative electrode material as described above.

[0021] Another object of the present invention is to provide a lithium - ion battery including the resin porous silicon carbon negative electrode material as described above.

[0022] The beneficial effects of the present invention are as follows:

[0023] The preparation method of the resin porous silicon carbon negative electrode material provided by the present invention uses resin as a raw material to prepare resin porous carbon, and then uses silane gas as a silicon source to introduce silicon elements into the resin porous carbon by pyrolyzing silane. On the one hand, it helps to avoid the agglomeration of silicon elements and improve the uniformity of silicon element distribution, thereby helping to improve the specific capacity of the negative electrode material while improving its cycling performance; on the other hand, using resin porous carbon as the supporting carbon skeleton for silicon elements and combining with the coating step of cured resin carbon can effectively reduce the volume expansion of the silicon - carbon material, and further help to improve the structural stability of the negative electrode material and ensure its cycling performance. Detailed embodiments

[0024] The present invention will now be described in further detail. The embodiments described below are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0025] To solve the problem of poor uniformity of silicon element distribution in the silicon-carbon anode material prepared in the prior art, the present invention provides a method for preparing a resin porous silicon-carbon anode material, which comprises the following steps:

[0026] S1: Hardening the resin to obtain a hardened resin;

[0027] S2: Crushing the hardened resin to obtain the crushed hardened resin;

[0028] S3: Heating the crushed hardened resin to 600 - 900 °C in an air atmosphere, holding for 5 h to achieve resin porousization, and then cooling to room temperature to obtain a resin carbon with a porous structure, denoted as intermediate product I;

[0029] S4: In a closed environment, introducing silane gas into intermediate product I, heating to 400 - 500 °C, and holding for 60 - 150 min to cause silane cracking. The silicon generated during the cracking process adheres to the inside of the porous structure of the resin carbon and the outer surface of the resin carbon to form intermediate product II;

[0030] S5: Mixing intermediate product II with the hardened resin prepared according to step S1 and grinding to obtain a resin porous silicon-carbon precursor;

[0031] S6: Heating the resin porous silicon-carbon precursor to 1000 - 1500 °C in an air atmosphere and holding for 5 h to complete the coating of the silicon-carbon material with the hardened resin, thereby obtaining a resin porous silicon-carbon anode material.

[0032] The method for preparing a resin porous silicon-carbon anode material provided by the present invention uses resin as a raw material to prepare resin porous carbon, and then uses silane gas as a silicon source to introduce silicon elements into the resin porous carbon by means of silane cracking. On the one hand, it helps to avoid silicon element agglomeration and improve the uniformity of silicon element distribution, thereby helping to improve the specific capacity of the anode material while improving its cycling performance; on the other hand, using resin porous carbon as the supporting carbon skeleton for silicon elements and combining with the coating step of hardened resin carbon can effectively reduce the volume expansion of the silicon-carbon material, and further help to improve the structural stability of the anode material and ensure its cycling performance.

[0033] In addition, in the preparation method of the resin porous silicon-carbon anode material provided by the present invention, silicon element is introduced into the system through silane cracking. Since hydrogen gas is generated during the silane cracking process, when the hydrogen gas escapes from the carbon material, on the one hand, it has a certain pore-expanding effect, and on the other hand, the silicon powder can be carried into the pore structure of the carbon material while the hydrogen gas escapes, which is more conducive to the uniform dispersion of the silicon powder, thereby helping to further improve the specific capacity and cycling performance of the anode material.

[0034] In the currently commonly used preparation method of silicon-carbon materials, porous carbon is usually prepared with graphite as the raw material, and elemental silicon is used as the silicon source. Through high-temperature and high-pressure conditions, after the elemental silicon evaporates, it is deposited on the inner surface of the porous carbon to achieve the purpose of attaching the silicon element inside the pores; the equipment required for this preparation method needs to have a strong pressure-bearing capacity, so the cost of purchasing such equipment is relatively high, and the energy demand for heating is relatively high, and the economy of this method is poor; at the same time, there is no supporting skeleton on the inner surface of the carbon where the silicon is distributed, and the expansion of silicon cannot be effectively inhibited, which is not conducive to improving the cycling performance of the silicon-carbon anode material.

[0035] In the preparation method of the resin porous silicon-carbon material provided by the present invention, silicon element is introduced into the system by means of silane cracking. The temperature required for cracking is not high, so the requirement for the equipment to withstand temperature is not high, and the overall preparation cost is relatively low, which helps to improve the economy of the preparation method.

[0036] The present invention preferably uses a thermosetting resin as the resin, so as to facilitate the hardening of the resin by means of thermal curing, which helps to simplify the preparation process.

[0037] The present invention preferably selects the resin from at least one of phenolic resin, alkyd resin, amino resin, polyester resin, epoxy resin, polyurethane resin, acrylic resin, silicone resin, vinyl resin, fluororesin, polyketone resin, aldehyde resin, aldehyde-ketone resin, petroleum resin, terpene resin, polyester fiber resin, nitrocellulose, cellulose acetate butyrate, chlorinated resin, furan resin, dammar resin, maleic resin.

[0038] The present invention further preferably uses phenolic resin or epoxy resin as the resin.

[0039] Specifically, the present invention preferably hardens the resin by: heating the resin to 150 - 250 °C and holding for 6 - 15 h to obtain the hardened resin.

[0040] To improve the uniformity of the dispersion of the silicon element, the present invention preferably selects the silane from at least one of silane and disilane.

[0041] To ensure the specific capacity of the resin porous silicon-carbon anode material, the present invention preferably sets the dosage ratio of the intermediate product I to the silane gas in step S4 as (45 - 50) g : 7 L.

[0042] To balance the specific capacity and cycle stability of the resin porous silicon-carbon anode material, in the present invention, the mass ratio of intermediate product II to the hardened resin in step S5 is preferably (5 - 10):1.

[0043] Silicon-carbon has the advantage of a large specific capacity per gram, but it is prone to swelling during charge and discharge. For the resin porous silicon-carbon anode material provided by the present invention, the silicon-carbon is supported by the carbon skeleton of the resin, which can relieve the swelling to a certain extent; further, the silicon-carbon is coated with resin, which can further inhibit its swelling; the present invention adopts the pyrolysis method of silane, which has low requirements for the temperature resistance of the equipment and the required pyrolysis temperature is also not high, and the overall cost is low, with high economic efficiency; at the same time, the gas generated by the pyrolysis method is hydrogen, which has a certain pore-expanding effect when escaping from the carbon material, and the hydrogen will carry the silicon powder to other pores when overflowing, which is more conducive to the uniform dispersion of the silicon powder.

[0044] Another object of the present invention is to provide a resin porous silicon-carbon anode material, which is prepared by the preparation method of the resin porous silicon-carbon anode material as described above.

[0045] For the resin porous silicon-carbon anode material provided by the present invention, resin is used as the raw material to prepare resin porous carbon during the preparation process, and then silane gas is used as the silicon source, and silicon elements are introduced into the resin porous carbon by the pyrolysis of silane. On the one hand, it helps to avoid the agglomeration of silicon elements and improve the uniformity of the silicon element distribution, thereby helping to improve the cycle performance while increasing the specific capacity of the anode material; on the other hand, using the resin porous carbon as the supporting carbon skeleton for the silicon element, combined with the coating step of the hardened resin carbon, can effectively reduce the volume expansion of the silicon-carbon material, and further help to improve the structural stability of the anode material and ensure its cycle performance.

[0046] The resin porous silicon-carbon anode material provided by the present invention has a rich pore structure. The silane is deposited therein and then pyrolyzed. The silicon-carbon particles are more stable with the resin porous carbon as the skeleton. Coating the silicon-carbon with resin can further inhibit the swelling of the silicon-carbon and improve its stability.

[0047] Another object of the present invention is to provide a lithium-ion battery, which includes the resin porous silicon-carbon anode material as described above.

[0048] The lithium-ion battery provided by the present invention uses the above-mentioned resin porous silicon carbon as the negative electrode material. During the preparation process of the resin porous silicon carbon negative electrode material, resin is used as the raw material to prepare resin porous carbon, and then silane gas is used as the silicon source. Silicon elements are introduced into the resin porous carbon by means of silane cracking. On the one hand, it helps to avoid the agglomeration of silicon elements and improve the uniformity of silicon element distribution, thereby helping to improve the specific capacity of the negative electrode material while enhancing its cycling performance. On the other hand, using resin porous carbon as the supporting carbon skeleton for silicon elements and combining with the coating step of hardened resin carbon can effectively reduce the volume expansion of the silicon-carbon material, help improve the structural stability of the negative electrode material, ensure its cycling performance, and further help to enhance the electrochemical performance of the lithium-ion battery.

[0049] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following provides a detailed description of specific embodiments of the present invention.

[0050] Example 1

[0051] This example provides a method for preparing a resin porous silicon carbon negative electrode material, including the following steps:

[0052] S1: Heat the phenolic resin to 220 °C and keep it warm for 10 hours to complete the hardening of the phenolic resin, obtaining hardened phenolic resin;

[0053] S2: Crush the hardened phenolic resin and grind it evenly to obtain the crushed hardened phenolic resin;

[0054] S3: In an air atmosphere, heat the crushed hardened phenolic resin to 870 °C, keep it warm for 5 h to make the phenolic resin porous, and then cool it to room temperature to obtain phenolic resin carbon with a porous structure, denoted as intermediate product I;

[0055] S4: In a closed environment, introduce 7 L of silane gas into 45 g of intermediate product I, heat it to 450 °C, and keep it warm for 90 min to fully crack the silane, forming intermediate product II;

[0056] S5: Mix intermediate product II with the hardened resin prepared according to step S1 in a mass ratio of 9:1 and grind it evenly to obtain a resin porous silicon carbon precursor;

[0057] S6: In an air atmosphere, heat the resin porous silicon carbon precursor to 1100 °C, keep it warm for 5 h to complete the coating of the hardened resin on the silicon-carbon material, obtaining the resin porous silicon carbon negative electrode material.

[0058] Example 2

[0059] This example provides a method for preparing a resin porous silicon carbon negative electrode material, including the following steps:

[0060] S1: Heat the epoxy resin to 200 °C and keep it at this temperature for 6 hours to complete the hardening of the epoxy resin, obtaining the hardened epoxy resin;

[0061] S2: Crush the hardened epoxy resin and grind it evenly to obtain the crushed and hardened epoxy resin;

[0062] S3: Under an air atmosphere, heat the crushed and hardened epoxy resin to 630 °C and keep it at this temperature for 5 h to make the epoxy resin porous, and then cool it to room temperature to obtain epoxy resin carbon with a porous structure, denoted as Intermediate Product I;

[0063] S4: In a closed environment, introduce 7 L of silane gas into 50 g of Intermediate Product I, heat it to 450 °C, and keep it at this temperature for 90 min to fully crack the silane, forming Intermediate Product II;

[0064] S5: Mix Intermediate Product II with the hardened resin prepared according to Step S1 in a mass ratio of 9:1 and grind it evenly to obtain a resin porous silicon-carbon precursor;

[0065] S6: Under an air atmosphere, heat the resin porous silicon-carbon precursor to 1100 °C and keep it at this temperature for 5 h to complete the coating of the silicon-carbon material by the resin, obtaining a resin porous silicon-carbon negative electrode material.

[0066] Example 3

[0067] This example provides a method for preparing a resin porous silicon-carbon negative electrode material, including the following steps:

[0068] S1: Heat the phenolic resin to 220 °C and keep it at this temperature for 10 hours to complete the hardening of the phenolic resin, obtaining the hardened phenolic resin;

[0069] S2: Crush the hardened phenolic resin and grind it evenly to obtain the crushed and hardened phenolic resin;

[0070] S3: Under an air atmosphere, heat the crushed and hardened phenolic resin to 870 °C and keep it at this temperature for 5 h to make the phenolic resin porous, and then cool it to room temperature to obtain phenolic resin carbon with a porous structure, denoted as Intermediate Product I;

[0071] S4: In a closed environment, introduce 7 L of disilane gas into 45 g of Intermediate Product I, heat it to 450 °C, and keep it at this temperature for 90 min to fully crack the disilane, forming Intermediate Product II;

[0072] S5: Mix Intermediate Product II with the hardened resin prepared according to Step S1 in a mass ratio of 9:1 and grind it evenly to obtain a resin porous silicon-carbon precursor;

[0073] S6: Heat the resin porous silicon-carbon precursor to 1100 °C in an air atmosphere, hold for 5 h, complete the coating of the silicon-carbon material with the hardened resin, and obtain the resin porous silicon-carbon anode material.

[0074] Comparative Example 1

[0075] This comparative example provides a method for preparing an anode material, including the following steps:

[0076] S1: Heat the phenolic resin to 220 °C, hold for 10 hours, complete the hardening of the phenolic resin, and obtain the hardened phenolic resin;

[0077] S2: Crush the hardened phenolic resin and grind it evenly to obtain the crushed hardened phenolic resin;

[0078] S3: In a closed environment, introduce 7 L of silane gas into 45 g of the crushed hardened phenolic resin, heat to 450 °C, hold for 90 min, and allow the silane to fully crack to form an intermediate product;

[0079] S4: Mix the intermediate product with the hardened resin prepared according to step S1 in a mass ratio of 9:1 and grind evenly to obtain the resin silicon-carbon precursor;

[0080] S5: Heat the resin silicon-carbon precursor to 1100 °C in an air atmosphere, hold for 5 h, complete the coating of the silicon-carbon material with the hardened resin, and obtain the resin silicon-carbon anode material.

[0081] Comparative Example 2

[0082] This comparative example provides a method for preparing an anode material, including the following steps:

[0083] S1: Heat the phenolic resin to 220 °C, hold for 10 hours, complete the hardening of the phenolic resin, and obtain the hardened phenolic resin;

[0084] S2: Crush the hardened phenolic resin and grind it evenly to obtain the crushed hardened phenolic resin;

[0085] S3: Heat the crushed hardened phenolic resin to 870 °C in an air atmosphere, hold for 5 h to make the phenolic resin porous, and then cool to room temperature to obtain the phenolic resin carbon with a porous structure, denoted as the intermediate product;

[0086] S4: In a closed environment, introduce 7 L of silane gas into 45 g of the intermediate product, heat to 450 °C, hold for 90 min, and obtain the anode material.

[0087] Comparative Example 3

[0088] This comparative example provides a method for preparing an anode material, including the following steps:

[0089] S1: Heat the phenolic resin to 220 °C and keep it at this temperature for 10 hours to complete the hardening of the phenolic resin, obtaining the hardened phenolic resin.

[0090] S2: Crush the hardened phenolic resin and grind it evenly to obtain the crushed hardened phenolic resin.

[0091] S3: Uniformly mix the crushed hardened phenolic resin and copper oxide in a mass ratio of 9:1, then heat the mixture to 800 °C and keep it at this temperature for 5 h to make the phenolic resin porous. After that, cool it down to room temperature and stir it in dilute nitric acid with a mass concentration of 10% for 8 hours, followed by washing with water, obtaining the phenolic resin carbon with a porous structure, denoted as Intermediate Product I.

[0092] S4: In a closed environment, introduce 7 L of silane gas into 45 g of Intermediate Product I, heat it to 450 °C, and keep it at this temperature for 90 min to fully crack the silane, forming Intermediate Product II.

[0093] S5: Mix Intermediate Product II and the hardened resin prepared according to Step S1 in a mass ratio of 9:1 and grind them evenly to obtain the resin porous silicon-carbon precursor.

[0094] S6: Under an air atmosphere, heat the resin porous silicon-carbon precursor to 1100 °C and keep it at this temperature for 5 h to complete the coating of the silicon-carbon material with the hardened resin, obtaining the resin porous silicon-carbon anode material.

[0095] Comparative Example 4

[0096] This comparative example provides a method for preparing an anode material, including the following steps:

[0097] S1: Add 5 mL of concentrated phosphoric acid with a concentration of 85 wt% to 50 g of epoxy resin and stir rapidly to obtain the hardened epoxy resin.

[0098] S2: Crush the hardened epoxy resin and grind it evenly to obtain the crushed hardened epoxy resin.

[0099] S3: Under an air atmosphere, heat the crushed hardened epoxy resin to 630 °C and keep it at this temperature for 5 h to make the epoxy resin porous. After that, cool it down to room temperature to obtain the epoxy resin carbon with a porous structure, denoted as Intermediate Product I.

[0100] S4: In a closed environment, introduce 7 L of silane gas into 45 g of Intermediate Product I, heat it to 450 °C, and keep it at this temperature for 90 min to fully crack the silane, forming Intermediate Product II.

[0101] S5: Mix Intermediate Product II and the hardened resin prepared according to Step S1 in a mass ratio of 9:1 and grind them evenly to obtain the resin porous silicon-carbon precursor.

[0102] S6: Heat the resin porous silicon-carbon precursor to 1100 °C in an air atmosphere and keep it at this temperature for 5 h to complete the coating of the silicon-carbon material with the resin, thereby obtaining the resin porous silicon-carbon anode material.

[0103] Comparative Example 5

[0104] This comparative example provides a method for preparing an anode material, which includes the following steps:

[0105] S1: Heat the phenolic resin to 220 °C and keep it at this temperature for 10 h to complete the hardening of the phenolic resin, thereby obtaining the hardened phenolic resin.

[0106] S2: Crush the hardened phenolic resin and grind it evenly to obtain the crushed hardened phenolic resin.

[0107] S3: Heat the crushed hardened phenolic resin to 870 °C in an air atmosphere and keep it at this temperature for 5 h to make the phenolic resin porous, and then cool it to room temperature to obtain the phenolic resin carbon with a porous structure, denoted as Intermediate Product I.

[0108] S4: In a closed environment, introduce 7 L of silane gas into 45 g of Intermediate Product I, heat it to 450 °C, and keep it at this temperature for 90 min to fully crack the silane and form Intermediate Product II.

[0109] S5: Perform chemical vapor deposition carbon coating on Intermediate Product II with a mixed gas of acetylene and argon. The flow rate of the mixed gas of acetylene and argon is 100 sccm, the volume fraction of acetylene in the mixed gas is 10%, the heating temperature is 900 °C, and the holding time is 1 h to complete the coating of the silicon-carbon material with the hardened resin, thereby obtaining the resin porous silicon-carbon anode material.

[0110] Prepare the anode materials obtained in the above examples and comparative examples into button cells according to the button cell process. The preparation process is as follows: Use the materials prepared in each example and comparative example as the negative electrode active materials, mix them evenly with polyvinylidene fluoride (PVDF) (dissolved in N-methylpyrrolidone) and conductive carbon black in a mass ratio of 90:5:5, coat them into an electrode film, place it in a vacuum drying oven and dry it at 120 °C for 12 h, roll and punch it to obtain the hard carbon negative electrode sheet; Use a lithium metal sheet as the counter electrode and 1 mol / L NaPF6 (EC-DEC = 1:1) as the electrolyte, assemble the above-obtained hard carbon negative electrode sheet into a 2430 button cell in a glove box to test its electrochemical performance; and prepare a monomer cell by combining the negative electrode material with a lithium iron phosphate positive electrode material, and use a vernier caliper to detect the expansion rate of the monomer cell after 5 cycles; The test results are shown in Table 1.

[0111] Table 1

[0112]

[0113] Examples 1-3 of the present invention are silicon-carbon supported by resinous porous carbon, and the silicon-carbon is coated with resin carbon. The specific capacity has been greatly improved compared with ordinary graphite, and the expansion rate of the single cell after 5 cycles is within 5%, indicating that the support of the resinous porous carbon skeleton and the coating of the resin carbon contribute to the stability of silicon-carbon and improve its cycling performance; Comparative Example 1 added silane on the premise that the resin carbon was not porous, but the resin carbon was coated. The results showed that although the specific capacity was greatly improved, the expansion rate of the single cell was large and the cycling performance was poor; Comparative Example 2 added silane on the premise that the resin carbon was porous, but the resin carbon was not coated. The results also showed a relatively large specific capacity, but the battery expansion rate was large and the cycling performance was poor; Compared with Example 1, Comparative Example 3 created pores by introducing metal oxides. The results showed that the expansion rate could be comparable to that of Example 1, but the specific capacity decreased significantly. It is estimated that the reason may be that the residual copper ions in the pores could not be completely removed, occupying the pores and affecting the specific capacity; Compared with Example 2, Comparative Example 4 crosslinked and hardened the epoxy resin by introducing concentrated phosphoric acid. The results showed that the expansion rate was comparable to that of Example 2, but the specific capacity decreased significantly. It is estimated that the reason may be that the phosphate groups were tightly combined with the functional groups in the pores, occupying the pores and affecting the specific capacity; Compared with Example 1, Comparative Example 5 carried out chemical vapor deposition carbon coating on Intermediate Product II with acetylene gas. The results showed that the expansion rate was larger than that of Example 1, and the specific capacity decreased significantly. It is estimated that the reason may be that the product of acetylene gas vapor deposition was acetylene black, which is used as a conductive agent in the lithium-ion battery process and has a very low specific capacity, so it affected the specific capacity of the subsequent results. The reason for the large expansion rate may be that acetylene black could not effectively inhibit the expansion of silicon-carbon.

[0114] Therefore, only under the dual action of the support of the porous resin carbon skeleton and the coating of the resin carbon can the expansion of silicon-carbon be better inhibited.

[0115] Taking the ideal embodiments of the present invention described above as an inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A preparation method of a resin porous silicon-carbon anode material, characterized in that, It includes the following steps: S1: Hardening the resin to obtain a hardened resin; S2: Crushing the hardened resin to obtain the crushed hardened resin; S3: Heating the crushed hardened resin to 600 - 900 °C in an air atmosphere and holding for 5 h to achieve resin porousization, obtaining Intermediate Product I; S4: In a closed environment, introducing silane gas into Intermediate Product I, heating to 400 - 500 °C, and holding for 60 - 150 min to crack the silane and form Intermediate Product II; S5: Mixing Intermediate Product II with the hardened resin and grinding to obtain a resin porous silicon - carbon precursor; S6: Heating the resin porous silicon - carbon precursor to 1000 - 1500 °C in an air atmosphere and holding for 5 h to obtain a resin porous silicon - carbon negative electrode material; The silane is selected from at least one of silane and disilane.

2. The preparation method of the resin porous silicon-carbon anode material according to claim 1, characterized in that, The resin is a thermosetting resin.

3. The preparation method of the resin porous silicon-carbon anode material according to claim 2, characterized in that, The resin is phenolic resin or epoxy resin.

4. The preparation method of the resin porous silicon-carbon anode material according to claim 2, wherein Hardening the resin includes: heating the resin to 150 - 250 °C and holding for 6 - 15 h to obtain the hardened resin.

5. The preparation method of the resin porous silicon-carbon anode material according to claim 1, characterized in that, In step S4, the dosage ratio of Intermediate Product I to the silane gas is (45 - 50) g : 7 L.

6. The preparation method of the resin porous silicon-carbon anode material according to claim 1, characterized in that, In step S5, the mass ratio of Intermediate Product II to the hardened resin is (5 - 10) :

1.

7. A resin porous silicon-carbon anode material, characterized in that, It is prepared by the preparation method of the resin porous silicon - carbon negative electrode material according to any one of claims 1 - 6.

8. A lithium-ion battery, characterized in that, It includes the resin porous silicon - carbon negative electrode material according to claim 7.

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