Silicon-oxygen-carbon composite composition and preparation method thereof

Abstract

The invention discloses a silicon-oxygen-carbon composite composition and a preparation method thereof, and relates to the technical field of silicon-oxygen-carbon composite compositions. The silicon-oxygen-carbon composite composition is prepared by taking cast iron as a raw material, SiOx and graphite are dispersed in a uniform embedding form and jointly form a gauze shape to exist in the composition, the preparation method comprises the steps of cast iron treatment, acid leaching, washing, drying and the like, and by effectively setting and selecting the raw materials and combining specific setting of all the steps, the silicon-oxygen-carbon composite composition is obtained. According to the method, the silicon-oxygen-graphite composite composition of the primary graphite can be obtained, the problem that the additional graphite is not uniformly dispersed is solved, the method is mild in process condition, low in cost and easy for large-scale production, and the obtained silicon-oxygen-carbon composite composition has wide application prospects in the fields of lithium ion battery negative electrode materials, electromagnetic wave absorbing materials and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of silicon-oxygen composite materials, and particularly relates to a silicon-oxygen-carbon composite material and a preparation method thereof. BACKGROUND

[0002] At present, the preparation process of silicon-oxygen-carbon composite materials (SiO x / C) mainly includes two technical routes of physical method and chemical method. The physical method (such as high-energy ball milling method) mainly realizes the composite of commercial graphite and nano-silicon or silicon dioxide powder through mechanical mixing, although the method is relatively simple, but has obvious limitations, that is, it is difficult to realize uniform dispersion at the nanoscale. Although the chemical method (such as chemical vapor deposition method CVD) can obtain good mixing effect, the process is complex, the equipment cost is high, the energy consumption is large, that is, the overall process intensity is large, and it is difficult to realize large-scale production, which seriously restricts its actual industrial application. The key problem in the preparation of silicon-oxygen-carbon composite materials has been how to realize the low-cost and efficient uniform composite of carbon source and silicon source. Moreover, in the prior art, graphite needs to be added additionally, and the additional addition of graphite inevitably introduces the problem of graphite agglomeration due to van der Waals force, thereby affecting the uniformity of the composite material.

[0003] Chinese patent application publication CN112421043A discloses a natural graphite negative electrode material and its application, which is obtained by acid leaching, carbon coating or silicon coating and high-temperature roasting to obtain a method of taking natural graphite as a negative electrode material, wherein the graphite is original, but since the silicon in the natural graphite exists in the form of impurities and the amount is relatively small, high-temperature roasting is needed to make it more ordered, and the method has high intensity.

[0004] Therefore, it is urgent to develop an innovative, low-intensity and simple, low-cost silicon-oxygen-carbon composite composition and a preparation method thereof. SUMMARY

[0005] Based on the above reasons, the purpose of the present application is to provide a preparation method of a silicon-oxygen-carbon composite composition by using Si, O and graphite which are all original together, through acid leaching extraction to ensure that the three elements still coexist but change the form of Si and O. The present application proposes a completely new technical solution: taking cast iron as raw material, through a low-intensity mechanical-chemical synergistic treatment process, in-situ synthesis of silicon-oxygen-carbon composite composition. This innovative method fundamentally avoids the technical problem of uneven dispersion caused by the addition of graphite, as the graphite and silicon-oxygen are all original, which provides a new solution to solve the technical problems in the industry.

[0006] In order to solve the above technical problems, the present application is realized by the following technical scheme.

[0007] According to the technical scheme of the present application, a silicon-oxygen-carbon composite composition is provided, which is prepared from cast iron as raw material, and has a chemical composition in terms of element atomic percentage of Si: 5.5-26.1 wt.%, O: 20.2-59.2 wt.%, and C: 22.3-63.5 wt.%, and in the microstructure of the silicon-oxygen-carbon composite composition, Si and O are in the form of SiO x , where 0 < x < 2, and C is in the form of graphite, and SiO x and graphite are in the form of uniform embedding and dispersion, and together form a thin silk and granular composite existing form in the composition, and the thin silk is the main body.

[0008] As a preferred, in the microstructure of the cast iron raw material, the graphite is in one or more of the forms of plate, fold, sphere, vermiculite, flocculation or coral (in the microstructure of the final silicon-oxygen-carbon composite composition, the morphology of the graphite is basically unchanged, only due to acid leaching, SiO x is more dispersedly attached).

[0009] As a preferred, the silicon-oxygen-carbon composite composition has two peak values of D peak of 1300-1400 / cm and G peak of 1560-1650 / cm in the Raman spectrum (which limits that the graphitization degree in the silicon-oxygen-carbon composite composition is very high).

[0010] A preparation method of a silicon-oxygen-carbon composite composition, which is used for preparing the above-mentioned silicon-oxygen-carbon composite composition, comprises the following steps: (1) cast iron treatment, selecting cast iron with C content of 3.0-4.5 wt.% and Si content of 2.0-3.0 wt.%, and then performing mechanical turning processing on the cast iron, with a turning speed of 90-800 m / min and a feed amount of 0.05-0.5 mm / r, to obtain cast iron turnings in the form of scraps, and in the microstructure, Si is in the form of Si element dissolved in Fe lattice and silicate and / or silicon oxide in the form of uniform and homogeneous morphology precursor.

[0011] (2) acid leaching, placing the cast iron turnings obtained in step (1) in a hydrochloric acid solution with a HCl concentration of 2-12 mol / L, heating to 30-80℃, and then stirring the mixture to perform acid leaching reaction, with a stirring time of 6-48 h, so that in the acid leaching reaction process, Si gradually changes from silica sol state to gel state (sticky Si-O-Si-O combined form), and at the same time, metal elements in the solid material are leached into the liquid phase, to obtain a solid-liquid mixture.

[0012] (3) washing and drying, vacuum filtering the mixture obtained in step (2) to obtain a filter cake and ferrous chloride solution by-product, repeatedly washing the filter cake until the filtrate is neutral, so that the filter cake gradually changes from a silica gel state to a SiO x and graphite composite form, and then transferring the washed filter cake to a drying device to dry at 60-130°C for 8-24h to obtain a silicon-oxygen-carbon composite composition.

[0013] Preferably, in step (1), the cast iron is one or more of gray cast iron, vermicular cast iron, ductile cast iron or malleable cast iron.

[0014] Preferably, in the microstructure of the cast iron chips in step (1), Si, O and C each element exists in the form of silicate and / or silicon oxide as the core and / or Si-Fe as the core, with graphite growing around the periphery of the core; and C exists in the form of graphite.

[0015] Preferably, the ferrous chloride solution by-product obtained in step (3) is directly used as a water purifying agent or a pigment after adjusting the concentration.

[0016] Preferably, in step (1), the parameters of mechanical turning are: turning speed 100-600 m / min, feed rate 0.1-0.3 mm / r.

[0017] Preferably, in step (2), the HCl concentration of the hydrochloric acid solution is 5-12 mol / L.

[0018] Preferably, in step (2), the temperature of the acid leaching reaction is 35-80°C, and the reaction time is 8-24h.

[0019] Preferably, in step (2), the stirring is magnetic stirring treatment, and the speed of the magnetic stirrer is 600-1200 rpm.

[0020] Preferably, in step (3), the filtrate is neutral, specifically the pH value of the filtrate is 6.8-7.3.

[0021] Preferably, after step (3), the following step is further included: (4) drying, further drying the product dried in step (3) in an oven or a vacuum drying oven at 80-120°C for 12-24h to obtain a dried silicon-oxygen-carbon composite composition product.

[0022] The application of the silicon-oxygen-carbon composite composition, the silicon-oxygen-carbon composite composition is the above-mentioned silicon-oxygen-carbon composite composition or the silicon-oxygen-carbon composite composition prepared by the above-mentioned preparation method, and the application is the application of the silicon-oxygen-carbon composite composition in a lithium ion battery negative electrode material or a wave absorbing material.

[0023] The technical effect of the present application is that: 1, the present application is found by studying the internal microstructure of the specific cast iron that there is a complex phase of silicon iron and silicon oxygen and graphite in the specific cast iron, and the graphite is originally around the silicon source, and the silicon content of the cast iron is an important limiting factor, if the silicon content is too high, the graphite exists in the form of blocks, which will directly precipitate in the liquid phase, and cannot form uniform graphite distribution in the subsequent treatment. By selecting this cast iron, and through a lot of research, it is found that the mechanical turning (the friction heat generated during turning forms a thin sheet, and the Si in the microstructure is in the form of Si element dissolved in the Fe lattice and in the form of uniform morphology precursor, which provides effective precursor for subsequent acid leaching) and hydrochloric acid leaching method (mainly used for leaching iron-based metals, while filling oxygen) can extract and form a thin silk and / or granular composite composition, and such composite composition will not have the problem of agglomeration due to van der Waals force because the graphite is original, and the Fe element in the cast iron accounts for more than 90wt.%, and other metal elements can be leached and removed, and through the treatment of acid leaching, the morphology of the graphite can be ensured without being affected too much (the dispersed metal element particles will have some effect on the morphology of the graphite after being removed, but will not have too much effect on the basic morphology of the graphite), and the Si and Si and O will change the morphology and finally disperse uniformly with the graphite in the form of SiO x Through acid leaching, as the pH value decreases, Si and Si and O can gradually change from the form of elemental silicon, silicate and / or silicon oxide to the form of silicon gel without changing the position, so as to disperse with the graphite more, after acid leaching, through water washing, the pH value gradually rises, and it gradually changes to the form of SiO x , so as to realize the original symbiotic SiO x embedded and dispersed uniformly in the graphite in the silicon-oxygen-ink composition, which greatly simplifies the subsequent treatment steps.

[0024] 2, The present application makes the overall extraction and preparation method unnecessary high-intensity treatment parameters such as high temperature and high pressure due to the particularity of the raw material, the whole process method condition is mild, and the cost is low, easy to scale, unnecessary complex and expensive equipment (such as CVD furnace, high-energy ball mill) or high-value raw materials (such as graphene, nano silicon powder). In the prior art, cast iron is generally used as a structural material, and the added value is relatively low, and the present application can extract SiO x And graphite composite, thereby greatly improving the added value of cast iron to a certain extent, realizing the transformation of waste into treasure, and being an innovative high-value utilization of material resources. At the same time, the reaction by-product of the process method of the present application is mainly ferrous chloride solution, which can be conveniently recovered for preparing water purifying agent, pigment, etc. after simple treatment, realizing that in the process of preparing raw materials with excellent electrical properties and wave absorption properties, there will be no adverse consequences to the environment, realizing green environmental protection and circular economy.

[0025] 3, The present application realizes the stability of the structure and performance of the obtained material by specifically controlling the parameters of each step, realizes the thickness of the sheet-shaped iron filings and the heat generated by friction by controlling the turning speed and the feed amount, thereby obtaining a uniform morphology of the precursor; by specifically controlling the concentration of hydrochloric acid solution and the heating temperature and time, the production efficiency is ensured, and effective silicon gel is obtained, if the concentration is too low or the temperature is too low, not only the speed of acid leaching iron element is reduced, but also the formation period of silicon gel is prolonged, which not only affects the final product morphology, but also the stirring time cannot meet the requirements, and if the temperature is too high, the reaction will be too violent; by specifically controlling each parameter, the microstructure, graphitization degree, silicon oxygen content and composite method of the final product can be effectively controlled, realizing the final product with controllable and stable microstructure. It has strong industrialization application potential and market competitiveness. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The present application is a process flow diagram.

[0027] Figure 2 The SEM of the silicon-oxygen-graphite composite in cast iron.

[0028] Figure 3 The SEM of the silicon-oxygen-carbon composite composition of an embodiment of the present application.

[0029] Figure 4 The SEM of another field of view of the silicon-oxygen-carbon composite composition of an embodiment of the present application and the element distribution diagram.

[0030] Figure 5XRD pattern of a silicon-oxygen-carbon composite composition according to an embodiment of the present application.

[0031] Figure 6 Raman spectrum of a silicon-oxygen-carbon composite composition according to an embodiment of the present application.

[0032] Figure 7 Charge-discharge cycle performance graph of a silicon-oxygen-carbon composite composition according to an embodiment of the present application as an anode for lithium ion batteries.

[0033] Figure 8 Performance graph of a silicon-oxygen-carbon composite composition according to Example 1 of the present application as a wave-absorbing material. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be further described below by combining with the embodiments and the drawings. In the specific embodiments, each feature is only an example of a series of equivalent or similar features unless specifically described. Only for the purpose of helping to understand the present application, the person skilled in the art should understand that the embodiments are only to help to understand the present application, and should not be regarded as a specific limitation on the present application.

[0035] Example 1 As shown in Figure 1 , the present embodiment shows a preparation method of a silicon-oxygen-carbon composite composition, comprising the following steps: (1) First, a vermicular cast iron rod with a diameter of 50 mm and C content of 3.5 wt% and Si content of 2.1 wt% is selected, and SEM detection is performed on the vermicular cast iron rod to obtain the SEM image as shown in Figure 2 . It can be seen from Figure 2 that there are Figure 2 agglomerates in the field of view of the cast iron, and the agglomerates are agglomerates with silicate and / or silicon oxide as the core and graphite surrounding the periphery. The vermicular cast iron rod is placed on a general lathe (CA6140 type), and a hard alloy tool is used to mechanically turn the cast iron, and the turning speed, feed rate and cutting depth are maintained at 100 m / min, 0.2 mm / r and 0.5 mm, respectively.

[0036] (2) 50 g of the turned iron filings are weighed and placed in a 600 mL three-necked round-bottom flask. 300 mL of a hydrochloric acid solution with a concentration of 12 mol / L is added to the flask, and the flask is placed in a magnetic stirrer (speed of 700 rpm) at 35°C, and the reaction is carried out for 10 h.

[0037] (3) After the reaction in step (2) is completed, the mixture is vacuum filtered, and the filter cake is repeatedly washed with deionized water until the filtrate is neutral (pH ≈ 7) as detected by pH paper. The washed wet filter cake is transferred to a vacuum drying oven and dried at 80°C for 12h, and finally the silicon-oxygen graphite composite material is obtained.

[0038] The silicon-oxygen graphite composite material obtained in this example is detected, and the results shown in Figure 3 , Figure 5 and Figure 6 are obtained.

[0039] As can be seen from Figure 3 , the obtained composition has a microstructure with a distributed thin silk-like structure as the main body and a granular structure as the supplement, Figure 3 and the unique thin silk-like structure can be seen in the center field of view. Figure 4 is the microstructure in another field of view, Figure 4 the upper left corner of the figure is a schematic of the thin silk-like structure in another field of view, Figure 4 the upper right corner of the figure is a distribution map of C elements, Figure 4 the lower left corner of the figure is a distribution map of O elements, Figure 4 and the lower right corner of the figure is a distribution map of Si elements. As can be seen from the four figures, Figure 4 from the element perspective, C, O and Si are dispersedly distributed in the same trend as the overall distribution of the thin silk-like structure, so that the thin silk-like distribution in the micro perspective is uniformly embedded and dispersed in each combination, and there is no excessive enrichment of a certain element, thereby proving that the SiO x and graphite in the silicon-oxygen graphite composite material prepared by the method of the present application are uniformly embedded and dispersed. In combination with the XRD pattern of the silicon-oxygen graphite composite material in Figure 5 , it can be seen that a very sharp graphite d (002) (002) plane diffraction peak is shown near 26°, which confirms that the graphite structure in the composition obtained in this example has good crystallinity; at the same time, it can be seen in Figure 5 that a "steamed bun peak" appears near about 23°, which is a typical amorphous silicon-oxygen characteristic peak, i.e., the composition obtained in Example 1 of the present application has a typical amorphous silicon-oxygen structure. At the same time, in combination with the Raman spectrum shown in Figure 6 , it can be clearly seen that there are two peaks, D peak (~1350 cm⁻¹) and G peak (~1580 cm⁻¹), corresponding to the defect peak and graphite carbon peak of carbon materials, respectively, and I D / I GThe value is approximately 0.36, which indicates that the graphitization degree of Example 1 of the present invention is very high. Such a composition and microstructure are generally considered to be beneficial to the improvement of electrochemical performance, thus proving that the silicon-oxygen-carbon composite composition prepared by the raw materials and methods of Example 1 of the present invention has very good electrochemical performance.

[0040] Furthermore, the silicon-oxygen-graphite composite material prepared in Example 1 was used as the active material for the negative electrode of a lithium-ion battery. The specific process is as follows: the active material, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 8:1:1 to form a slurry. This slurry was then uniformly coated onto a copper foil current collector, and after vacuum drying at 80°C for 12 hours, it was cut into sheets to form the negative electrode. In an argon-filled glove box, a lithium sheet was used as the counter electrode, and the electrolyte was 1 mol / L. -1 LiPF6 in EC:DEC 1:1v:v (containing 10wt% FEC additive) was assembled into CR2032 coin cells. Electrochemical performance was tested using the Xinwei Battery Testing System, and the results were as follows: Figure 7 The results shown are from Figure 7 It can be seen from this that at 0.2 Ag -1 At a current density of 310 mAh g, its initial discharge specific capacity reaches 310 mAh g. -1 The initial charge capacity is 170.5mAh. -1 The coulomb efficiency was 55% in the first week. After 700 cycles, its reversible specific capacity remained stable at 200 mAh g. -1 The left and right sides exhibit excellent cycle stability.

[0041] Furthermore, we also tested it as an absorbing material and obtained the following results: Figure 8 The test results shown are obtained through Figure 8 It can be seen that its minimum reflection loss RL was found. min The value is -23.77 dB, which reflects the absorption efficiency of the absorbing material for electromagnetic waves. The larger the negative value, the stronger the absorption capability. The RL value obtained in this embodiment is... min A value of -23.77 dB indicates that the material obtained in this embodiment achieves an absorption capacity of -23.77 dB for electromagnetic waves at a specific frequency. Since the frequency range where RL ≥ -10 dB is defined in absorbing materials to reflect the material's effective absorption of electromagnetic waves across a wide frequency band, the composition obtained in this embodiment belongs to a superior absorption level. Furthermore, testing revealed that the maximum effective bandwidth EAB of the material obtained in this embodiment is 2.55 GHz, indicating that the material's absorption performance consistently meets the "effective absorption" standard within the 2.55 GHz bandwidth, demonstrating its broadband absorption potential. Simultaneously, through... Figure 8It can be seen that all the curves of silicon-oxygen-carbon composite materials of different thicknesses have a wave-absorbing peak in a certain frequency range (near 14-16 GHz), which reflects the spectral response law of the silicon-oxygen-carbon composite material of the embodiment, and the materials with thicknesses of 4.70 mm and 4.78 mm respectively exhibit a minimum reflection loss of -23.77 dB and a maximum effective bandwidth of 2.55 GHz, which proves that the silicon-oxygen-carbon composite material of the embodiment has good wave-absorbing performance. Figure 8 It can be obtained that when the thickness of the embodiment is selected, the material with a corresponding thickness can be selected from the figure according to the wave-absorbing requirement of the target frequency band, and thin materials are preferred for high-frequency bands, and relatively thick materials are preferred for wide-frequency bands. Figure 8 It can be seen that the material of the embodiment 1 has good wave-absorbing performance and can be used as a wave-absorbing material.

[0042] Embodiment 2 The embodiment shows a preparation method of a silicon-oxygen-carbon composite composition, which comprises the following steps: (1) First, a ductile iron rod with a diameter of 50 mm (C is 3.6 wt%, Si content is 2.0 wt%) is placed on a general lathe (CA6140 type), and a hard alloy tool is used for mechanical turning of the cast iron, and the turning speed, feed rate and cutting depth are kept at 180 m / min, 0.3 mm / r and 0.6 mm respectively.

[0043] (2) 200 g of turned iron filings are weighed and placed in a 2000 mL three-necked round-bottom flask. 800 mL of 10 mol / L hydrochloric acid solution is added to the flask. The flask is placed in a magnetic stirrer (speed is 1000 rpm) at 40°C, and the reaction is carried out for 16 h.

[0044] (3) After the reaction is completed, the mixture is vacuum filtered, and the filter cake is repeatedly washed with deionized water until the filtrate is neutral (pH ≈ 7) using pH test paper. The washed wet filter cake is transferred to a vacuum drying oven and dried at 90°C for 24 h to obtain a silicon-oxygen-graphite composite material.

[0045] Further, the electrochemical performance is detected, and the silicon-oxygen-graphite composite material prepared in the embodiment is used as an active material for a lithium ion battery negative electrode. The specific process test procedure is as follows: 1. The active material, conductive agent acetylene black and binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 8:1:1 in an N-methyl pyrrolidone (NMP) solvent to form a slurry, which is then uniformly coated on a copper foil current collector, and after vacuum drying at 80°C for 12 h, the negative electrode sheet is cut into pieces.

[0046] 2. In an argon-filled glove box, lithium sheet is used as the counter electrode, and the electrolyte is 1 mol / L LiPF6 / EC-DMC-EMC (volume ratio of 1:1:1) solution. -1LiPF6 in EC:DEC1:1 v:v (containing 10wt% FEC additive), assembled into CR2032 type button cell.

[0047] Electrochemical performance test was carried out using a new battery test system, and the first discharge specific capacity reached 277mAh g -1 at a current density of 0.2 A g -1 , the first charge specific capacity was 144.04mAh g -1 , and the first week coulombic efficiency was 52%.

[0048] In addition, we also used it as a wave-absorbing material, and found that its minimum loss RL min value was-20.45dB, and the maximum effective bandwidth EAB was 2.35GHz.

[0049] Example 3 This embodiment shows a preparation method of a silicon-oxygen-carbon composite composition, comprising the following steps: (1) First, a forgeable cast iron rod with a diameter of 50mm (C is 3.3wt%, Si content is 2.2wt%) is placed on a general lathe (CA6140 type), and a hard alloy tool is used for mechanical turning of the cast iron, and the turning speed, feed amount, and cutting depth are kept at 200 m / min, 0.35 mm / r, and 0.4 mm respectively.

[0050] (2) 100g of turned iron filings are weighed and placed in a 1000mL three-necked round-bottom flask. 500mL of 8mol / L hydrochloric acid solution is added to the flask. The flask is placed in a magnetic stirrer (speed is 800rpm) at 55℃, and the reaction is carried out for 14h.

[0051] (3) After the reaction is completed, the mixture is vacuum filtered, and the filter cake is repeatedly washed with deionized water until the filtrate is neutral (pH≈7) using pH test paper. The washed wet filter cake is transferred to a vacuum drying oven and dried at 100℃ for 18h to obtain a silicon-oxygen-graphite composite material.

[0052] Further, the electrochemical performance is detected, and the silicon-oxygen-graphite composite material prepared in this embodiment is used as an active material for a lithium ion battery negative electrode. The specific process is as follows: 1. The active material, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 8:1:1 in N-methyl pyrrolidone (NMP) solvent to prepare a slurry, which is then uniformly coated on a copper foil current collector, and after vacuum drying at 80℃ for 12h, the negative electrode sheet is cut and prepared.

[0053] 2, in the glove box filled with argon, lithium sheet as the counter electrode, electrolyte for 1 1 molL -1 LiPF6 in EC:DEC 1:1v:v (containing 10wt% FEC additive), assembled into CR2032 type button cell.

[0054] Electrochemical performance test was carried out using new battery test system, at 0.2 Ag -1 The first discharge specific capacity reached 285mAhg -1 , the first charge specific capacity was 142.5mAhg -1 , the first week coulombic efficiency was 50%.

[0055] In addition, we also used it as a wave-absorbing material, and found that the minimum loss RL min The value was-21.58dB, and the maximum effective bandwidth EAB was 2.43GHz.

[0056] The technical principles of the present application are described above in combination with specific embodiments. These descriptions are only for the purpose of explaining the principles of the present application, and cannot be interpreted in any way as a limitation on the scope of protection of the present application. Based on the explanations here, those skilled in the art can think of other specific embodiments of the present application without creative labor, and these embodiments will fall within the scope of protection of the present application.

Claims

1. A silicon oxycarbide composite composition, characterized in that, The silicon-oxygen-carbon composite composition is prepared from cast iron as raw material, and has a chemical composition containing, in terms of element atomic percentage, Si: 5.5-26.1 wt.%, O: 20.2-59.2 wt.%, and C: 22.3-63.5 wt.%, and in the microstructure thereof, Si and O are in the form of SiO x , wherein 0 < x < 2, and C exists in the form of graphite, and SiO x and graphite are in a uniformly embedded form and are dispersedly compounded, and together form a form of coexisting in the composition in the form of a thin silk and granular composite, and the thin silk is the main body.

2. The silicon oxycarbide composite composition of claim 1, wherein, In the microstructure of the cast iron raw material, the graphite exists in one or more of the forms of platelet, wrinkle, sphere, vermicular, flocculus, and coral.

3. A method for producing a silicon-oxygen-carbon composite composition, characterized by, The preparation method is used for preparing the silicon-oxygen-carbon composite composition in claim 1 or 2, and comprises the following steps: (1) cast iron treatment, selecting cast iron with C content of 3.0-4.5 wt.% and Si content of 2.0-3.0 wt.%, and then performing mechanical turning processing on the cast iron, with turning speed of 90-800 m / min and feed rate of 0.05-0.5 mm / r, to obtain cast iron chips with the microstructure of Si in the form of elemental Si dissolved in the Fe lattice and Si in the form of silicate and / or silicon oxide in the form of uniform and homogeneous precursor; (2) acid leaching, placing the cast iron chips obtained in step (1) in a hydrochloric acid solution with HCl concentration of 2-12 mol / L, heating to 30-80℃, and then stirring the mixture to perform acid leaching reaction, with stirring time of 6-48 h, so that in the acid leaching reaction process, Si gradually changes from silica sol state to gel state, and at the same time, metal elements in the solid material are leached into the liquid phase, to obtain a solid-liquid mixture; (3) washing and drying, vacuum filtering the mixture obtained in step (2) to obtain a filter cake and a ferrous chloride solution by-product, repeatedly washing the filter cake until the filtrate is neutral, so that the Si in the filter cake gradually transforms from a gel state to finally exist in the form of SiO x and graphite composite, and then transferring the washed filter cake to a drying device to dry at 60-130°C for 8-24h to obtain a silicon-oxygen-carbon composite composition.

4. The production method according to claim 3, characterized by, In step (1), the cast iron is one or more of gray cast iron, vermicular graphite cast iron, nodular graphite cast iron, or malleable cast iron.

5. The preparation method according to claim 3, characterized in that, In step (1), in the microstructure of the cast iron chips, Si, O, and C each exist in the form of silicate and / or silicon oxide as the core and / or in the form of Si-Fe as the core, with graphite growing around the periphery of the core.

6. The preparation method according to claim 3, characterized in that, The ferrous chloride solution by-product obtained in step (3) is directly used as a water purifying agent or a pigment after adjusting the concentration.

7. The preparation method according to claim 3, characterized in that, In step (1), the parameters of the mechanical turning are as follows: turning speed of 100-600 m / min and feed rate of 0.1-0.3 mm / r.

8. The production method according to claim 3 or 7, characterized by, In step (2), the HCl concentration of the hydrochloric acid solution is 5-12 mol / L; In step (2), the temperature of the acid leaching reaction is 35-80℃, and the reaction time is 8-24 h; In step (2), the stirring is magnetic stirring treatment; In step (2), the metal elements are one or more of Fe as the main element, and Mn, Cr, Ni, Mo, Cu, Al, Ti, or V as impurities or alloy elements.

9. The preparation method according to claim 3, characterized in that, After step (3), the following step is further included: (4) drying, further drying the product dried in step (3) in an oven or a vacuum drying oven at 80-120℃ for 12-24 h, to obtain a dried silicon-oxygen-carbon composite composition product.

10. Use of a silicon-oxygen-carbon composite composition, characterized in that The application of the silicon-oxygen-carbon composite composition is the application of the silicon-oxygen-carbon composite composition in a lithium ion battery negative electrode material or a wave-absorbing material.

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