Preparation method of iodine-doped C / SiO composite lithium battery anode material based on rich-carbon coal gasification slag x ​

Abstract

The present invention discloses a preparation method of a carbon-rich coal gasification slag-based iodine-doped C / SiO x composite lithium battery anode material, belonging to the field of lithium battery anode materials; First, the present invention uses a nitric acid solution to pretreat the carbon-rich coal gasification slag to remove metal impurities and obtain a solid residue; Then, the pore channels of the solid residue are modified and reformed by chemical activation to prepare a porous C / SiO x composite material; Finally, iodine (I2) is deposited on the surface and inner pore walls of the porous C / SiO x composite material by fumigation to finally obtain the anode material.

Description

Technical Field

[0001] The present invention relates to the field of methods or devices for directly converting chemical energy into electrical energy, specifically to the field of anode materials for lithium batteries, and particularly to a preparation method of an iodine-doped C / SiO x composite anode material for lithium batteries based on carbon-rich coal gasification slag. Background Art

[0002] Coal gasification technology is known as the leading technology in the modern coal chemical industry and can provide syngas for the entire backend chemical production; however, a large amount of coal gasification slag will inevitably be generated during the coal gasification process. Coal gasification slag has a large output, low utilization rate, high treatment cost and poses an environmental threat. Stockpiling and landfill are still the main disposal methods for coal gasification slag.

[0003] Coal gasification slag contains elements such as Si, Al, C, Ca, Fe, etc. and has high potential for resource utilization. Coal gasification slag includes two parts: coarse slag and fine slag. Among them, after the coal gasification fine slag is flotation-treated, the carbon-rich part (40% < residual carbon content < 80%) obtained is called carbon-rich coal gasification slag. The carbon content of carbon-rich coal gasification slag is relatively high and it cannot be used as building materials and soil improvers, while its carbon content is lower than that of the high-carbon part, seriously affecting its circulating co-combustion. Therefore, the recovery and utilization rate of carbon-rich coal gasification slag is relatively low and the output value is limited. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of an iodine-doped C / SiO x composite anode material for lithium batteries based on carbon-rich coal gasification slag, and use carbon-rich coal gasification slag to prepare an iodine-doped C / SiO x composite anode material for lithium batteries.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The present invention provides a preparation method of an iodine-doped C / SiO x composite anode material for lithium batteries, and the method comprises the following steps:

[0007] Step 1: Soak carbon-rich coal gasification slag with nitric acid solution to remove metal elements, and then filter to obtain a solid residue containing C, Si, O (C / SiO x ) and waste liquid; the solid residue is washed with water and dried to obtain a solid residue powder (C / SiO x ) removing metal impurities.

[0008] Step 2: Perform structural reorganization on the solid residue prepared in Step 1 to prepare a porous C / SiO x composite material; the method comprises the following steps:

[0009] Step 2.1: Mix the solid residue powder obtained in Step 1 with a powdery chemical activator, then place it in deionized water and soak it under heating conditions. This treatment can promote the full entry of the chemical activator into the structure of the solid residue. Then, directly perform drying treatment to obtain a dry mixture. The chemical activator used is any one of phosphoric acid, KOH, K2CO3, and KHCO3.

[0010] Step 2.2: Put the dry mixture into a tubular furnace with nitrogen as the protective gas for carbonization activation to obtain an activated product. The carbonization activation temperature is 600 - 800 °C.

[0011] Step 2.3: Soak the activated product in a nitric acid solution to remove the activator and its products. Then, filter, wash with water, and dry to obtain a porous C / SiO x composite material.

[0012] Step 3: Deposit I2 on the surface and inner walls of the pores of the porous C / SiO x composite material prepared in Step 2 by fumigation to obtain a carbon-rich coal gasification slag-based iodine-doped C / SiOx composite lithium battery anode material. During fumigation, the porous C / SiO x composite material is spread above the iodine.

[0013] Furthermore, in a specific embodiment of the present invention, in Step 1, the concentration of the nitric acid solution used is 2.0 mol / L; the dosage relationship between the carbon-rich coal gasification slag and the nitric acid solution is 1 g:8 mL; the soaking time is 36 h. After soaking treatment, filter to obtain a solid residue and waste liquid, then wash the solid residue with distilled water until neutral, and then place it in a blast drying oven for drying to obtain a solid residue powder (C / SiO x ) after removing metal impurities.

[0014] Furthermore, in a specific embodiment of the present invention, in Step 2.1, the dosage relationship between the solid residue and the chemical activator is 1:2 - 6 by mass ratio. Then, place the mixture in deionized water and soak it in an oil bath at 70 °C for 24 h. Then, directly put it into a blast drying oven at 110 °C for drying for 24 h to obtain a dry mixture.

[0015] Furthermore, in a specific embodiment of the present invention, in Step 2.2, put the dry mixture into a tubular furnace with nitrogen as the protective gas for carbonization activation for 2 h.

[0016] Further, in a specific embodiment of the present invention, in step 2.3, the concentration of the nitric acid solution used is 1 mol / L; the dosage relationship between the activation product and the nitric acid solution is 1 g:5 mL in terms of mass-volume ratio, and the soaking time is 24 h; then the solid is obtained by filtration, washed with distilled water until neutral, and dried in a blast drying oven at 110 °C to obtain porous C / SiO x composite material.

[0017] Further, in a specific embodiment of the present invention, in step 3, on the surface and inner wall of the pores of the porous C / SiO x composite material prepared in step 2, the method for depositing I2 is as follows: Place iodine at the bottom of a porcelain boat, and spread the porous C / SiO x composite material prepared in step 2 above the iodine. The mass ratio of the porous C / SiO x composite material to iodine is 2 - 6:1; Place the porcelain boat into a tube furnace, and under the condition that the nitrogen gas flow rate is the first flow rate, heat it at a heating rate of 1 - 5 °C / min to 180 - 185 °C, and then keep it warm for the first time; After that, raise the temperature to 195 °C, and increase the nitrogen gas flow rate to the second flow rate, and purge for the second time to blow off the excess iodine on the surface of the material. Finally, cool it to room temperature to obtain a carbon-rich coal gasification slag-based iodine-doped C / SiOx composite lithium battery anode material.

[0018] Preferably, in step 3, the first flow rate is 1 m / s, and the first time is 0.5 - 1.5 h; the second flow rate is 4 - 10 m / s, and the second time is 5 - 20 min.

[0019] Further, all the waste liquids generated in the above method of the present invention are neutralized with potassium hydroxide, and then the metal hydroxide precipitate is removed by filtration to obtain liquid fertilizer. Thus, the high-value utilization, zero emission, zero pollution, and green application of carbon-rich coal gasification slag are realized.

[0020] The beneficial effects of the present invention are as follows: The present invention provides a preparation method for a carbon-rich coal gasification slag-based iodine-doped C / SiOx composite lithium battery anode material. First, the present invention uses a nitric acid solution to pretreat the carbon-rich coal gasification slag to remove metal impurities and obtain a solid residue. Then, the pore channels of the solid residue are modified and reformed by chemical activation to prepare porous C / SiO x composite material. Finally, through the fumigation method, I2 is deposited on the surface and inner wall of the pores of the porous C / SiO x composite material, and finally the anode material is prepared.

[0021] The material characteristics of the present invention are described as follows:

[0022] In the present invention, the introduction of I2 can reduce C / SiO xThe porosity of the composite material is reduced, internal defects are decreased, the carbon layer spacing of the material is increased, and irreversible reactions during the first lithiation process are reduced. Additionally, the introduction of I2 can also form some closed small pores inside the material, effectively promoting the desolvation process.

[0023] More importantly, the lithium-ion batteries prepared from the materials of the present invention have more excellent performance. Specifically, after I2 deposited on the surface and inner wall of the pores of the material enters the electrolyte, I3 is generated accordingly. − . During the first discharge process, LiI3 and SiO x react to insert lithium to generate LiI, LiIO3 and Si. During the charging process, LiIO3 and Si react to generate SiO x and LiI. Then, LiI undergoes de-lithiation to generate LiI3. Therefore, through the disproportionation reaction of I2 itself, the reversible reaction of SiO x is effectively promoted, and the formation of irreversible Li4SiO4 and Li2O is reduced. Additionally, the intermediate products LiI3 and LiIO3 can inhibit the decomposition of electrolyte components and LiPF6, forming a relatively thin solid electrolyte film. Finally, the initial Coulombic efficiency of the porous C / SiO x material is increased from 57.1% to 88.5%, and the reversible specific capacity is increased from 350 mAh / g to 1241 mAh / g.

[0024] In summary, the negative electrode material prepared by the present invention has both a high reversible specific capacity, a low electrode reaction resistance, good rate performance, excellent cycle stability, and a high initial Coulombic efficiency. Brief Description of the Drawings

[0025] Figure 1 Shown are the SEM image, TEM image, HRTEM image, and energy spectrum (EDS) element mapping image of the sample of Example 1 of the present invention.

[0026] Figure 2 Shown is the performance detection result image of the 18650 cylindrical battery prepared by the present invention.

[0027] Figure 3 Shown is the thermogravimetric analysis image of the samples of Examples 1-3 and Comparative Example 1 of the present invention.

[0028] Figure 4 Shown is the XRD image of the samples of Examples 1-3 and Comparative Example 1 of the present invention.

[0029] Figure 5 Shown are the N2 adsorption-desorption curves and pore size distribution curves of the samples of Examples 1-3 and Comparative Example 1 of the present invention.

[0030] Figure 6Shown are the scanning electron microscope (SEM) images of the samples of Examples 1-3 and Comparative Example 1 of the present invention.

[0031] Figure 7 Shown are the SEM image, TEM image, and HRTEM image of the sample of Comparative Example 1 of the present invention.

[0032] Figure 8 Shown are the statistical curve graphs of the electrode rate performance tests of the samples of Examples 1-3 and Comparative Example 1 of the present invention.

[0033] Figure 9 Shown are the statistical curve graphs of the cyclic stability test results of the electrodes prepared from the samples of Examples 1-3 and Comparative Example 1 of the present invention at 0.1 A / g.

[0034] Figure 10 Shown are the statistical graphs of the first Coulombic efficiency tests of the electrodes prepared from the samples of Examples 1-3 and Comparative Example 1 of the present invention at 0.1 A / g.

[0035] Figure 11 Shown are the high-resolution transmission electron microscope photos of the electron microscopes of the samples of Examples 1-3 and Comparative Example 1 of the present invention.

[0036] Figure 12 Shown is the schematic diagram of the lithium-ion storage mechanism of the working electrode of the present invention.

[0037] Figure 13 Shown are the charge-discharge X-ray diffraction pattern and HRTEM image of the electrode of Comparative Example 1 of the present invention under the condition of 0.1 A / g.

[0038] Figure 14 Shown is the ex-situ Raman curve of the electrode prepared in Example 1 of the present invention after 10 cycles at 0.1 A / g. Detailed implementation manners

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without any creative efforts shall fall within the protection scope of the present invention.

[0040] The raw materials used in the present invention are described as follows:

[0041] The carbon-rich coal gasification slag has a residual carbon content of 40% < residual carbon content < 80%. In addition to carbon, its main components also include a large amount of silicon oxide and aluminum oxide, and the impurity components mainly include elements such as calcium, magnesium, iron, sodium, and titanium. The following Table 1 shows the component analysis table of the carbon-rich coal gasification slag used in the embodiments of the present invention, and this carbon-rich coal gasification slag is provided by a coal chemical enterprise in Ordos City, Inner Mongolia.

[0042] Table 1. Composition analysis table of the carbon-rich gasification slag used in the embodiments of the present invention

[0043]

[0044] Next, the present invention will provide multiple embodiments and comparative experiments to illustrate the technical details of the present invention.

[0045] Example 1. Preparation method of a C / SiO x @10%I composite lithium battery anode material, comprising the following steps:

[0046] Step 1. Screen the carbon-rich gasification slag raw material, select the carbon-rich gasification slag powder passing through 150 and 200 meshes as the raw material, mix the screened carbon-rich gasification slag and the nitric acid solution with a concentration of 2.0 mol / L at a mass-to-volume ratio of 1 g:8 mL, and soak for 36 h to remove metal elements; after the acid pretreatment is completed, filter to obtain a solid residue and waste liquid, then wash the solid residue with distilled water until neutral, and then place it in a blast drying oven to dry to obtain a solid residue with metal impurities removed.

[0047] The following table 2 shows the element and composition content table of the solid residue after the treatment in step 1 of Example 1 of the present invention

[0048]

[0049] Step 2. Mix the solid residue and KHCO3 powder at a mass ratio of 1:4, and then place it in deionized water and soak at 70 °C for 24 h. Then, put it into a blast drying oven at 110 °C, evaporate the water and dry for 24 h to obtain a dried mixture. Then, put the dried mixture into a tubular furnace with nitrogen as the protective gas and carbonize and activate at 700 °C for 2 h; then, soak the activated product in a 1 mol / L nitric acid solution at a mass-to-volume ratio of 1 g:5 mL for 24 h to remove the activator and its products. Then filter to obtain a solid, wash the solid with distilled water until neutral, and put it into a blast drying oven at 110 °C to dry to obtain a porous C / SiO x Composite material.

[0050] Step 3. Place iodine at the bottom of a porcelain boat, spread the prepared porous C / SiO x Composite material above the iodine, and the mass ratio of the porous C / SiO x Composite material to iodine is 4:1; put the porcelain boat into the tubular furnace, and under the condition that the nitrogen flow rate is 1 m / s, heat it to 183 °C at a heating rate of 3 °C / min, and then keep it warm for 1 h. Then, raise the temperature to 195 °C, and increase the nitrogen flow rate to 7 m / s and blow for 10 min to blow off the excess iodine on the surface of the material. Finally, cool to room temperature to obtain a carbon-rich gasification slag-based iodine-doped C / SiO xComposite lithium battery anode material. The iodine content of the sample prepared in this example is 10.04%, named C / SiO x @10%I.

[0051] The following Table 3 shows the element and composition content table of the sample prepared in Example 1 of the present invention

[0052]

[0053] The following Table 4 shows the pore structure parameter table of the sample prepared in Example 1 of the present invention

[0054]

[0055] The morphology of the sample in Example 1 was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the element distribution was analyzed by energy dispersive spectrometer (EDS). As Figure 1 shown are the SEM image, TEM image, HRTEM image, and energy spectrum (EDS) element mapping image of the sample in Example 1 of the present invention. Among them, (a) is the SEM image; (b, c) are the transmission electron microscopy (TEM) images at different magnifications; (d) is the HRTEM image (the inserted image is the lattice spacing profile of the selected rectangular area); (e) is the energy spectrum (EDS) element mapping image.

[0056] From Figure 1 a, it can be seen that the surface of the material prepared in the present invention is uneven, with many pore structures of uneven sizes, and these characteristics are beneficial to the full contact between the electrolyte and the electrode material. From Figure 1 b, it can be seen that the nanoscale I2 particles are uniformly distributed on the surface of the composite material. From Figure 1 c, it can be seen that the silicon oxide particles are uniformly dispersed in the carbon skeleton; from Figure 1 d, it can be seen that the material is amorphous carbon without obvious and regular lattice fringes; Figure 1 e shows that the element distribution is uniform, indicating that the I element is uniformly distributed in the carbon skeleton, which can effectively improve the contact between iodine and silicon oxide particles and enable them to react fully. In addition, the uniform distribution of each element can also effectively relieve the volume expansion of silicon oxide.

[0057] Furthermore, the present invention applies the C / SiO x @10%I composite lithium battery anode material prepared in Example 1 to prepare a 18650 cylindrical battery. The specific method is as follows:

[0058] The C / SiO x @10%I composite lithium battery anode material prepared in Example 1 and graphite are mixed at a mass ratio of 91:9 and used as the anode. With Li[Ni 0.8 Co 0.1 Mn0.1 Using O2 as the positive electrode, an 18650 cylindrical battery with a designed capacity of 1500 mAh was then assembled.

[0059] More specifically, Li[Ni 0.8 Co 0.1 Mn 0.1 O2 material was used as the positive electrode material, mixed in the ratio of positive electrode material: conductive agent: binder = 92:5:3, and wet mixed for 24 hours using a planetary mixer. The viscosity of the slurry was controlled at 3500 ± 200 mPa·s. The preparation of the PVDF glue solution required controlling the temperature ≤ 30°C and the linear speed of the dispersion disc at 13 m / s to prevent the glue solution from denaturing. The particle size of the positive electrode material was accurate to 3 - 5 microns, and plasma treatment was used to increase the binding force of the current collector by 40%.

[0060] Using a mixture of 9%C / SiO x @10%I graphite as the negative electrode material, mixed in the ratio of negative electrode material: conductive agent: binder = 92:5:3. During mixing, the humidity was controlled ≤ 200 ppm, and for aqueous mixing, it was necessary to ensure that the conductivity of deionized water was ≤ 1 μS / cm. In the dry mixing stage, low-speed stirring (15 - 20 rpm) was used, combined with circulating water cooling to avoid material agglomeration.

[0061] During the production process of the electrode sheet, the coating thickness error was ≤ ±1.5 μm. The magnetic levitation coating system monitored the coating amount in real time, and the first efficiency cycle reached 92.5%. The slurry was sieved to remove particles > 45 μm and ferromagnetic substances, and the mesh number of the sieve needed to match the particle size of the material. After the electrode sheet was dried, it was rolled by a pair of rollers to increase its density to 3.4 - 3.6 g / cm 3 , and when cutting the burrs, it was necessary to control ≤ 5 μm. After the aluminum foil / copper foil was plasma cleaned, the surface tension was ≥ 38 mN / m to enhance the adhesion of the coating.

[0062] During the battery assembly process, a fully automatic winding machine was used with a positioning accuracy of ±0.1 mm and a winding core alignment error of ≤ 0.3 mm. Before assembling the steel shell, it was necessary to clean and remove metal debris, and the liquid injection was completed in a million-class clean workshop. Vacuum liquid injection technology was used, and the liquid injection amount error was controlled within ±0.05 g. After liquid injection, it was left to stand for 12 - 24 hours to ensure sufficient penetration.

[0063] Next, the performance of the prepared 18650 cylindrical battery was tested. A blue electric test system was used to detect the cycle stability of the electrode. The test environment temperature was controlled at 25°C, and continuous charge and discharge tests were carried out at a rate of 5C.

[0064] The test results are as follows:

[0065] As Figure 2The figure shows the performance test results of the 18650 cylindrical battery prepared by the present invention. Among them, (a) is the 18650 cylindrical battery with a designed capacity of 1500 mAh; (b) is the discharge / charge curve of the battery at a 5C charge and discharge rate; (c) is the discharge capacity curve; (d) is the energy density curve of the graphite / C / SiO x @10%I||Li[Ni 0.8 Co 0.1 Mn 0.1 O2 and graphite||Li[Ni 0.8 Co 0.1 Mn 0.1 O2 full battery.

[0066] As can be seen from Figure 2 b, at a 5C charge and discharge rate, the initial discharge capacity of this full battery is 1565 mAh, and the capacity stabilizes at 1421 mAh after 300 cycles, with a capacity retention rate of 91% ( Figure 2 c). Compared with the graphite||Li[Ni 0.8 Co 0.1 Mn 0.1 O2 full battery, adding 9% of the C / SiO in Example 1 x @10%I composite material can increase the energy density of graphite||Li[Ni 0.8 Co 0.1 Mn 0.1 O2 by about 25 Wh / kg ( Figure 2 d). Appropriately adding the C / SiO in Example 1 x @10%I composite material can significantly increase its power density while affecting the capacity and capacity retention rate of the full battery.

[0067] Furthermore, in the present invention, by changing some process conditions in Step 3, carbon-rich gasification slag-based iodine-doped C / SiOx composite lithium battery anode materials with different doping amounts can be prepared. This will be illustrated by multiple specific examples below.

[0068] Example 2. A preparation method of a C / SiO x @8%I composite lithium battery anode material, comprising the following steps:

[0069] Perform Step 1 and Step 2 of Example 1. Step 3 is as follows: Place iodine at the bottom of a porcelain boat, and lay the porous C / SiO x composite material above the iodine, and the porous C / SiO xThe mass ratio of the composite material to iodine is 2:1; place the porcelain boat in a tube furnace, and under the condition that the nitrogen flow rate is 1 m / s, heat it at a heating rate of 5 °C / min to 185 °C and keep it warm for 1.5 h. Then, increase the nitrogen flow rate to 10 m / s and purge at 195 °C for 5 min to blow off the excess iodine on the surface of the material. Cool to room temperature to obtain carbon-rich coal gasification slag-based iodine-doped C / SiO x Composite lithium battery anode material. The iodine content of the sample obtained in this example is 8.24%, and it is named C / SiO x @8%I according to the iodine content.

[0070] Example 3. A preparation method of C / SiO x @12%I composite lithium battery anode material, including the following steps:

[0071] Execute steps 1 and 2 of Example 1, and step 3 is as follows: Place iodine at the bottom of the porcelain boat, and lay the porous C / SiO x composite material above the iodine. The porous C / SiO x The mass ratio of the composite material to iodine is 6:1; place the porcelain boat in a tube furnace, and under the condition that the nitrogen flow rate is 1 m / s, heat it at a heating rate of 1 °C / min to 180 °C and keep it warm for 0.5 h. Then, increase the nitrogen flow rate to 4 m / s and purge at 195 °C for 20 min to blow off the excess iodine on the surface of the material. Cool to room temperature to obtain carbon-rich coal gasification slag-based iodine-doped C / SiO x Composite lithium battery anode material. The iodine content of the sample obtained in this example is 12.24%, and it is named C / SiO x @12%I according to the iodine content. Comparative Example 1

[0072] Execute steps 1 and 2 of Example 1, and do not execute step 3. Obtain a porous C / SiO x composite material sample.

[0073] The products prepared in Examples 1-3 and Comparative Example 1 were studied by comparison as follows:

[0074] First, the following Table 5 shows the statistical table of the element and component contents of the samples in Examples 1-3 and Comparative Example 1

[0075]

[0076] The following Table 6 is the statistical table of the pore structure parameters of the samples in Examples 1-3 and Comparative Example 1 of the present invention

[0077]

[0078] Secondly, the present invention analyzes the composition of the composite materials in Examples 1-3 and Comparative Example 1 by thermogravimetric analysis (TGA). As attachedFigure 3 Shown are the thermogravimetric analysis diagrams of the samples of Examples 1-3 and Comparative Example 1 of the present invention. The TGA curves indicate that the mass loss of the C / SiOx@I composite material between 180 °C and 300 °C is mainly attributed to the volatilization of I2. These composite materials contain approximately 8%, 10%, and 12% of I2 (Table 5).

[0079] Next, the present invention used X-ray diffraction (XRD) to analyze the phase structure and purity of the composite materials of Examples 1-3 and Comparative Example 1. As Figure 4 Shown are the XRD diagrams of the samples of Examples 1-3 and Comparative Example 1 of the present invention.

[0080] As Figure 4 shown, the XRD pattern of the composite material of Comparative Example 1 has a broad peak at 26 o °, indicating the presence of amorphous C and amorphous SiO x in the composite material. After adding I2, the diffraction peak of the composite material of the Example shifts by a small angle, which is because the atomic diameter of I (0.266 nm) is larger than that of C or Si. As I2 is incorporated into the carbon layer, the interlayer spacing of the C skeleton layer increases, resulting in the diffraction peak shifting towards a smaller angle. Expanding the C layer spacing is beneficial to the diffusion of Li + and electrons, thereby improving the conductivity of the C / SiO x negative electrode. In addition, this expansion of the C layer can also reduce the lithium storage dead zones in the C / SiO x negative electrode and improve its initial Coulombic efficiency and cycle stability.

[0081] As Figure 5 shown are the N2 adsorption-desorption curves and pore size distribution curves of the samples of Examples 1-3 and Comparative Example 1 of the present invention; among them, (a) is the N2 adsorption-desorption curve and (b) is the pore size distribution curve.

[0082] From Figure 5 and Table 6, it can be seen that the sample of Comparative Example 1 exhibits a high specific surface area of 405 m² / g, and the pore size is mainly between 0.3 and 7 nm ( Figure 5 b). As the content of I2 increases, the specific surface area and pore volume of the C / SiO x @I composite material gradually decrease, while the pore size gradually increases (Table 6). This is because the I2 vapor diffuses into the pores of the porous C / SiO x and adheres to the inner wall of its pores, resulting in the micropores of C / SiO x being blocked and reducing the size of its mesopores. Fortunately, the reduced specific surface area reduces the contact between the electrode material and the electrolyte, thereby minimizing the side reactions related to electrolyte decomposition and solid electrolyte membrane formation.

[0083] As Figure 6Shown are the scanning electron microscope (SEM) images of the samples of Examples 1-3 and Comparative Example 1 of the present invention. Among them, Figure (a) shows the SEM image of the sample of Comparative Example 1; (b) shows the SEM image of the sample of Example 1; (c) shows the SEM image of the sample of Example 2; (d) shows the SEM image of the sample of Example 3.

[0084] As can be seen from Figure 6 it, the C / SiO x composite material has an irregular black blocky morphology before and after modification. High-magnification scanning electron microscope images show that the surface of the C / SiO x composite material is covered with pores of different sizes. With the increase in the content of I2, the number of pores on the surface of the C / SiOx@I composite material decreases, and the pore diameter increases, further confirming the results of BET.

[0085] As Figure 7 shown are the SEM image, TEM image, HRTEM image, and energy-dispersive spectroscopy (EDS) element mapping image of the sample of Comparative Example 1 of the present invention. Among them, (a) is the SEM image; (b) is the transmission electron microscope (TEM) image at different magnifications; (c) is the HRTEM image (the inserted image is the lattice spacing profile of the selected rectangular area).

[0086] As can be seen from Figure 1 it, nanoscale I2 particles are uniformly distributed on the surface of the C / SiO x @10%I composite material in Example 1 ( Figure 1 b), while the surface of the C / SiO x composite material in Comparative Example 1 is smooth and has a clear contour ( Figure 7 a). Figure 1 The high-resolution transmission electron microscope (HRTEM) images of c and Figure 7 b show that SiO x nanoparticles are uniformly embedded in the C skeleton, and both the C / SiO x and C / SiO x @10%I composite materials exhibit an amorphous structure without obvious crystal lattices ( Figure 1 d and Figure 7 c). After adding I2, the interlayer spacing of the C layer expands from 0.34 nm to 0.45 nm ( Figure 1 d and Figure 7 c), which can effectively slow down the volume expansion and particle agglomeration of SiO x and I2 during charge and discharge. The energy-dispersive spectrometer (EDS) image of the C / SiO x @10%I composite material ( Figure 1e) The display elements are evenly distributed, indicating that iodine elements are evenly distributed in the carbon skeleton, which can effectively improve the contact between iodine and silicon oxide particles and enable them to fully react. In addition, the uniform distribution of each element can effectively relieve the volume expansion of silicon oxide.

[0087] Furthermore, the present invention prepared the working electrodes from the samples of Examples 1-3 and Comparative Example 1 and conducted the detection of the electrode rate performance. The specific method is as follows:

[0088] The working electrode was made by mixing 80 wt.% C / SiO x @I (or C / SiO x )), 10 wt.% Super-P carbon black and 10 wt.% sodium alginate in an aqueous solution. The mass loading of the electrode was 1.8~2.6 mg / cm 2 . The electrolyte was 1.0 mol / L LiPF6, which was composed of ethylene carbonate (EC), methyl carbonate (EMC) and dimethyl carbonate (DMC) (EC: EMC: DMC, volume ratio 1:1:1).

[0089] Lithium sheet (counter electrode), separator (Celgard series), electrolyte (carbonate solution containing LiPF6). All components (such as battery case, electrode sheet, separator, etc.) need to be vacuum dried for 12 hours to remove moisture. The gas needs to be replaced more than three times before operating in the glove box to ensure an inert atmosphere. Glove box (water and oxygen content <1 ppm), vacuum drying oven (60-80 °C), tablet press (pressure 50 MPa), pipette gun (accurately control the amount of electrolyte).

[0090] Assembly sequence (starting from the positive electrode case) Positive electrode case → positive electrode sheet → electrolyte (0.1-0.2 mL) → separator (soaked in electrolyte) → lithium sheet (negative electrode) → gasket → spring piece → negative electrode case. The injection error of the electrolyte needs to be controlled within ±0.02 mL, and the separator needs to be completely soaked. Use a digital display tablet press to seal at a pressure of 50 MPa to ensure that the contact resistance <0.5 mΩ56. After standing for 4 hours, the open circuit voltage was detected, and abnormal values (such as <2.5 V) needed to check for short circuit risks.

[0091] Electrochemical experiments were carried out using 2025-type button cells, and the detection method is as follows:

[0092] At room temperature, in the voltage range of 0.01~3.0 V (relative to Li / Li + ), on a LAND-3100A battery tester, the electrochemical performance at different current densities was evaluated using constant current charge-discharge curves.

[0093] The detection results are as follows:

[0094] As Figure 8The figure shows the statistical curve graphs of the rate performance detection of the sample electrodes of Examples 1-3 and Comparative Example 1 of the present invention. It can be seen from the figure that within the tested current density range, compared with the C / SiOx electrode in Comparative Example 1, the C / SiOx@I electrodes prepared from the materials of Examples 1-3 all exhibit higher reversible capacities. In addition, with the increase of the I2 content, the reversible capacity of the C / SiOx@I electrode first increases and then decreases. Specifically, the reversible capacities of the C / SiO x @10%I electrode at current densities of 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, and 2.5 A / g are 1244, 1018, 934, 843, 806, 744, and 644 mAh / g respectively ( Figure 8 ). It is worth noting that when the current density increases by 25 times, the capacity retention rate is still as high as 51.7%. In addition, when the current density is restored from 2.5 A / g to 0.1 A / g, the reversible capacity of C / SiO x @10%I basically recovers, showing excellent rate performance.

[0095] Furthermore, the present invention carried out a cyclic stability test on the electrodes prepared from the samples of Examples 1-3 and Comparative Example 1 at 0.1 A / g. The cyclic stability of the electrodes was detected using a Blue-E test system, and the test ambient temperature was controlled at 25°C. Under a current density of 0.1 A / g, continuous charge and discharge tests were carried out.

[0096] The detection results are as follows:

[0097] As Figure 9 shown is the statistical curve graph of the cyclic stability test results of the electrodes prepared from the samples of Examples 1-3 and Comparative Example 1 of the present invention at 0.1 A / g. As Figure 10 shown is the statistical graph of the first Coulombic efficiency test of the electrodes prepared from the samples of Examples 1-3 and Comparative Example 1 of the present invention at 0.1 A / g (where 8%I corresponds to the sample C / SiOx@8%I of Example 2, 10%I corresponds to the sample C / SiOx@10%I of Example 1, and 12%I corresponds to the sample C / SiOx@12%I of Example 3).

[0098] From Figure 9 it can be seen that at a current density of 0.1 A / g, the reversible capacities of all the C / SiO x @I electrodes in the examples are significantly higher than those of the C / SiO x electrodes in the comparative example; in addition, with the increase of the I2 addition concentration, their reversible capacities first increase and then decrease. After 3 cycles, the C / SiO xThe discharge capacity of the 10%I electrode reaches 1266 mAh / g at 0.1 A / g. After 100 cycles, the discharge capacity remains at 1241 mAh / g, with a retention rate of 98.0%. C / SiO of Example 1 x The first Coulombic efficiency of the 10%I electrode is 88.5%, higher than that of the C / SiO in Comparative Example 1 x electrode (57.1%) and the other two C / SiO x @I electrodes (the C / SiOx@8%I of Example 2 is 79.2%, and the C / SiO of Example 3 x @12%I is 80.4%) ( Figure 10 ).

[0099] Furthermore, as Figure 11 shown are the high-resolution transmission electron microscope photos of the samples of Examples 1-3 and Comparative Example 1 of the present invention. It can be seen from Figure 11 that after cycling 50 times at 0.1 A / g, the solid electrolyte film on the C / SiO x electrode in Comparative Example 1 remains uniform, with a thickness of about 7.5 nm. In contrast, the solid electrolyte film on the C / SiOx@I electrode becomes significantly thinner after the introduction of I2. In addition, with the increase in the I2 addition concentration, the thickness of the solid electrolyte film on the C / SiO x @I electrode in the examples shows a trend of first decreasing and then increasing ( Figure 11 b-d). Through density functional theory (DFT) calculations, it is found that the electron affinity of I3 - and LiIO3 is lower than that of other electrolyte components including LiPF6, indicating that LiI3 and LiIO3 can effectively inhibit the decomposition of LiPF6 and other electrolyte components, thereby reducing the thickness of the solid electrolyte film. However, due to the volume expansion caused by the insertion of lithium ions into I2, the solid electrolyte film on the surface of the C / SiO x @I electrode is damaged and more Li + is required to repair the damaged solid electrolyte film. This results in the formation of a thick and non-uniform solid electrolyte film ( Figure 11 d), thereby leading to a lower first Coulombic efficiency.

[0100] Furthermore, the present invention studied the lithium ion storage mechanism of the above working electrode. The research process is as follows:

[0101] As Figure 12The figure shows a schematic diagram of the lithium-ion storage mechanism of the working electrode of the present invention. In the figure, a) is the X-ray diffraction pattern and HRTEM image of the electrode discharged to 1.8 V at 0.1 A / g; b) is the X-ray diffraction pattern and HRTEM image of the electrode discharged to 0.01 V; c) is the X-ray diffraction pattern and HRTEM image of the electrode charged to 1.1 V; d) is the X-ray diffraction pattern and HRTEM image of the electrode after 50 cycles at 3.0 V; e) is a simulation diagram of the chemical changes of each component during the charge and discharge process of the electrode, and f) is a corresponding detailed electro-chemical reaction schematic diagram.

[0102] Figure 13 This is the charge-discharge X-ray diffraction pattern and HRTEM image of the electrode of Comparative Example 1 of the present invention under the condition of 0.1 A / g; among them, a) is the X-ray diffraction pattern and HRTEM image discharged to 0.01 V, and b) is the X-ray diffraction pattern and HRTEM image after charging to 3.0 V and 50 cycles.

[0103] Figure 14 This is the ex-situ Raman curve of the electrode prepared in Example 1 of the present invention after 10 cycles at 0.1 A / g; among them, a) is the charge-discharge curve; b) is the Raman spectrum of the marked point in (a); c) is the optimized structure of Si loaded on the surface of LiIO3(100).

[0104] In order to reveal the electro-chemical reaction mechanism of the electrodes prepared in Example 1 and the comparative example, ex-situ XRD, HRTEM and Raman spectroscopy analyses were carried out at specific charge-discharge potentials. After the electrode of Example 1 was discharged to 1.8 V, characteristic diffraction peaks and lattice fringes of LiIO3, LiI and Si were observed ( Figure 12 a), corresponding to the lithiation process of LiI3 and SiO x (ii: 3SiO x + I3 - +3Li + + 2e - → xLiIO3 + (3-x)LiI + 3Si).

[0105] When further discharged to 0.01 V, the diffraction peaks and lattice fringes of Si were replaced by the diffraction peaks and lattice fringes of Li 13 Si4 ( Figure 12 b), indicating that the formed Si was further converted into Li 13 Si4 (iii: 4Si + 13Li + + e - →Li 13 Si4).

[0106] When charged to 1.1 V, only the diffraction peaks and lattice fringes of LiI were observed ( Figure 12 c), indicating that Li 13 Si4 loses Li + to form Si (iv: Li 13 Si4 → 4Si + 13Li + + 13e - ), while LiIO3 reacts with Si to form SiO x and LiI (v: xLiIO3 + 3Si → 3SiO x + xLiI).

[0107] When further charged to 3.0 V, the LiI peak disappeared and the electrode showed an amorphous state ( Figure 12 d), LiI degraded to form LiI3 (vi: 3LiI→LiI3 + 2Li + + 2e - ), being in an amorphous state.

[0108] The simulated charge-discharge reaction process diagrams of the Example 1 electrode are shown in Figure 12 e, f. On the contrary, when discharged to 0.01 V, the Example 1 electrode showed the diffraction peaks and lattice fringes of Li 13 Si4, Li2O and Li4SiO4 ( Figure 13 a), indicating that lithiation reactions occurred for SiO x and the by-product Si. When charged to 3.0 V, the Li 13 Si4 peak disappeared, while the Li2O and Li4SiO4 peaks persisted ( Figure 13 b), indicating that the lithiation of SiO x to form Li2O and Li4SiO4 is irreversible, which is the main reason for the low initial Coulomb efficiency of the SiO x electrode.

[0109] The ex-situ Raman spectra of the electrode prepared in Example 1 during charge-discharge are shown in Figure 14 . The main signal observed was the symmetric stretching vibration peak of I3 - in the range of 115~125 cm -1 ( Figure 14 b). During discharge, the I3 - peak appeared at the first 4 positions, and its intensity gradually decreased, indicating that the reaction between I3 - and SiO x was ongoing. When the electrode was discharged to 1.8 V, the I3 - peak completely disappeared, indicating that all of the I3 -is consumed in the reaction, which is consistent with the above ex-situ XRD analysis. On the contrary, during the charging process, the I3 - peak reappears at about 1.9 V and its intensity gradually increases, confirming the reverse reaction of the conversion of LiI back to I3 - . Therefore, it is proved again that through the disproportionation reaction of I2 itself, the reversible reaction of SiO x is effectively promoted, reducing the formation of irreversible Li4SiO4 and Li2O. Further improving the initial Coulombic efficiency of the SiO x electrode.

[0110] Furthermore, in the present invention, carbon-rich coal gasification slag-based iodine-doped C / SiOx composite lithium battery anode materials with different doping amounts can be prepared by changing the process conditions. This will be demonstrated by multiple specific examples below.

[0111] Composite lithium battery anode materials are prepared using different chemical activators to study their characteristics. The specific method is as follows:

[0112] Based on Example 1, only the type of chemical activator is changed, and other process conditions remain unchanged to prepare composite lithium battery anode materials. The chemical activators used are four activators: phosphoric acid, KOH, K2CO3, and KHCO3.

[0113] The following Table 7 is a statistical table of the pore structure parameters of the porous C / SiO x composite materials prepared with four activators: phosphoric acid, KOH, K2CO3, and KHCO3

[0114]

[0115] The following Table 8 is a statistical table of the component analysis and corresponding electrochemical performance analysis of the iodine-doped C / SiO x composite materials obtained after doping iodine into the porous C / SiO x composite lithium battery anode materials

[0116]

[0117] The comparative analysis is as follows:

[0118] It can be seen from the above data analysis that different activators have different pore-forming abilities under the same process conditions. Specifically, the pore-forming effect of phosphoric acid is inferior to the other three (Table 7), so under the same iodine-doping conditions, the least amount of iodine infiltrates (Table 8).

[0119] As described above, the disproportionation reaction of I2 itself can effectively promote SiO xTo achieve a reversible reaction and reduce the formation of irreversible Li4SiO4 and Li2O. If the iodine content is insufficient, there are still two irreversible substances generated. On the contrary, if the iodine content is too high, introducing too much I2 will also cause the pores inside the material to be blocked, affecting the diffusion of Na + and electrons, thereby reducing the rate performance and cycling stability of the material; in addition, iodine and iodides have high solubility in organic electrolytes, resulting in a decrease in the utilization rate of active substances and a decline in cycling stability; at the same time, the iodide-containing SEI film will also affect its stability. Finally, the intrinsic conductivity of iodine is low, which in turn affects the electrochemical performance. These factors jointly determine the initial Coulomb efficiency, sodium storage capacity, rate performance, and cycling stability of the I2-doped C / SiO x negative electrode material. Therefore, as the iodine content increases, the initial Coulomb efficiency and capacity retention rate of the iodine-doped C / SiO x composite lithium battery negative electrode material show a trend of first increasing and then decreasing (Table 8). Finally, it is determined that under the same conditions, the iodine-doped C / SiO x composite material obtained by doping the porous C / SiO x composite lithium battery negative electrode material prepared with the KHCO3 activator has the best chemical properties.

[0120] Furthermore, the present invention studies the characteristics of composite lithium battery negative electrode materials prepared with different amounts of KHCO3. The specific method is as follows:

[0121] Based on Example 1, only the amount of KHCO3 is changed; specifically, the solid residue powder for removing metal impurities and the KHCO3 powder are mixed at mass ratios of 1:2, 1:3, 1:4, 1:5, and 1:6 respectively; other process conditions remain unchanged, and composite lithium battery negative electrode materials are prepared.

[0122] As shown in Table 9 below, it is the statistical table of the pore structure parameters of the porous C / SiO x composite material

[0123]

[0124] As shown in Table 10 below, it is the statistical table of the component analysis and corresponding electrochemical performance analysis of the iodine-doped C / SiO x composite material obtained by doping the porous C / SiO x composite lithium battery negative electrode material

[0125]

[0126] The comparative analysis is as follows:

[0127] It is found by comparison that as the amount of KHCO3 increases, C / SiO xThe specific surface area of the composite material shows a trend of first increasing and then decreasing. When the mass ratio of the gasification slag powder to the KHCO3 powder is 1:5, C / SiO x The specific surface area of the composite material is the largest (Table 9). This is because when the dosage of KHCO3 is too large during the pore-forming process, the micropores and mesopores formed collapse and become macropores, resulting in a decrease in the specific surface area of the C / SiO x composite material.

[0128] Similarly, under the same iodine doping conditions, as the specific surface area of the C / SiO x composite material increases, the amount of iodine infiltrated gradually increases. In addition, with the increase in iodine content, the first Coulomb efficiency and capacity retention rate of the iodine-doped C / SiO x composite lithium battery anode material show a trend of first increasing and then decreasing (Table 10). Finally, it is determined that under the same conditions, when the mass ratio of the gasification slag powder to the KHCO3 powder is 1:4, the porous C / SiO x composite material after iodine doping, the iodine-doped C / SiO x composite lithium battery anode material has the best chemical properties.

[0129] Furthermore, the present invention studies the characteristics of the composite lithium battery anode material prepared at different carbonization activation temperatures in step 2. The specific method is as follows:

[0130] Based on Example 1, only the carbonization activation temperature is changed; specifically, the carbonization activation temperatures are 600 °C, 700 °C, and 800 °C respectively; other process conditions remain unchanged, and the composite lithium battery anode material is prepared.

[0131] As shown in Table 11 below, it is the statistical table of the pore structure parameters of the porous C / SiO x composite material

[0132]

[0133] As shown in Table 12 below, it is the statistical table of the composition analysis and corresponding electrochemical performance of the iodine-doped C / SiO x composite material obtained after iodine doping of the porous C / SiO x composite lithium battery anode material

[0134]

[0135] The comparative analysis is as follows:

[0136] It is found by comparison that as the carbonization activation temperature increases, the specific surface area of the C / SiO x composite material shows a trend of first increasing and then decreasing. When the carbonization activation temperature is 700 °C, C / SiO xThe specific surface area of the composite material is the largest (Table 11). This is because when the carbonization activation temperature is too high, during the pore formation process, the formed micropores and mesopores collapse and turn into macropores, resulting in x a decrease in the specific surface area of the composite material.

[0137] Similarly, under the same iodine doping conditions, as the x specific surface area of the composite material increases, the amount of infiltrated iodine gradually increases. In addition, as the iodine content increases, the initial Coulombic efficiency and capacity retention rate of the iodine-doped C / SiO x composite lithium battery anode material show a trend of first increasing and then decreasing (Table 12). Finally, it is determined that under the same conditions, when the mass ratio of gasification slag powder to KHCO3 powder is 1:4, the prepared porous C / SiO x composite material after iodine doping, the iodine-doped C / SiO x composite lithium battery anode material has the best chemical properties.

[0138] Furthermore, the present invention studied the characteristics of the composite lithium battery anode material prepared with different iodine doping amounts, different heating rates, different reaction temperatures, and different heat preservation times in step 3. The specific method is as follows:

[0139] Based on Example 1, change a single variable according to the data in the following table; other process conditions remain unchanged, and the composite lithium battery anode material is prepared.

[0140] As shown in Table 13 below, it is the composition analysis of the iodine-doped C / SiO x composite lithium battery anode material obtained under different iodine infiltration conditions and the corresponding statistical table of electrochemical performance analysis

[0141]

[0142] The comparative analysis is as follows:

[0143] It is found by comparison that as the mass ratio of the hierarchical porous C / SiO x composite material to iodine increases, the iodine content in the iodine-doped C / SiO x composite lithium battery anode material gradually increases; this is because when the heating rate, temperature, and heat preservation time remain unchanged, the rates of iodine deposition and movement are the same, so for a large amount of iodine used, the retention rate is high. And it decreases with the increase of the heating rate, temperature, and heat preservation time (Table 13). This is because when the iodine dosage is the same, increasing the heating rate, temperature, and heat preservation time will all increase the volatilization amount of iodine and reduce its retention rate. In addition, as mentioned above, too high or too low iodine content in the iodine-doped C / SiO x composite lithium battery anode material will significantly affect its electrochemical performance. Therefore, the optimal hierarchical porous C / SiO xThe mass ratio of the composite material to iodine is 4:1, the optimal heating rate is 3 °C / min, the optimal temperature is 183 °C, and the optimal heat preservation time is 1 h).

[0144] Furthermore, the present invention studied the characteristics of the composite lithium battery anode material prepared under different purging conditions in step 3. The specific method is as follows:

[0145] Based on Example 1, the nitrogen gas flow rate was changed; specifically, the nitrogen gas flow rates were set to 4 m / s, 7 m / s, and 10 m / s respectively; other process conditions remained unchanged, and the composite lithium battery anode material was prepared. In addition, based on Example 1, the purging time was changed; specifically, the purging times were set to 5 min, 10 min, 15 min, and 20 min respectively; other process conditions remained unchanged, and the composite lithium battery anode material was prepared.

[0146] The following Table 14 shows the composition analysis of the iodine-doped C / SiO x Statistical table of the composite lithium battery anode material composition analysis and the corresponding electrochemical performance

[0147]

[0148] The comparative analysis is as follows:

[0149] It was found by comparison that as the nitrogen gas flow rate and purging time during purging increased, the iodine content in the iodine-doped C / SiO x composite lithium battery anode material gradually decreased (Table 14). This is because, at the same purging time, the greater the nitrogen gas flow rate, the lower the iodine retention rate; if the nitrogen gas flow rate is fixed, the longer the purging time, the lower the iodine retention rate. Similarly, too high or too low iodine content in the iodine-doped C / SiOx composite lithium battery anode material will significantly affect its electrochemical performance. Therefore, the optimal nitrogen gas flow rate is 7 m / s, and the optimal purging time is 10 min.

[0150] It can be understood that the present invention is described through some embodiments. Those skilled in the art know that without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. In addition, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. Preparation method of iodine-doped C / SiO x composite lithium battery anode material based on carbon-rich coal gasification slag, characterized in that The method includes the following steps: Step 1: Immerse the carbon-rich gasification slag in a nitric acid solution to remove metal elements, and then filter to obtain a solid residue containing C, Si, and O and a waste liquid; the solid residue is washed with water and dried to obtain a solid residue powder with metal impurities removed. Step 2. Perform structural reforming on the solid residue obtained in Step 1 to prepare a porous C / SiO x composite material; the method includes the following steps: Step 2.1: Mix the solid residue powder prepared in Step 1 with a powdered chemical activator, then place it in deionized water and soak it under heating conditions; then, directly dry it to obtain a dry mixture; the chemical activator used is any one of KOH, K2CO3, and KHCO3. Step 2.2: Place the dry mixture in a tubular furnace with nitrogen as the protective gas for carbonization activation to obtain an activated product; the carbonization activation temperature is 600-800°C. Step 2.3: Immerse the activated product in a nitric acid solution to remove the activator and its products; then filter, wash with water, and dry to obtain a porous C / SiO x composite material; Step 3: Deposit I2 on the surface and inner walls of the pores of the porous C / SiO x composite material prepared in Step 2. Place iodine at the bottom of a porcelain boat, and lay the porous C / SiO x composite material prepared in Step 2 above the iodine. The mass ratio of the porous C / SiO x composite material to iodine is 2 - 6:

1. Place the porcelain boat into a tube furnace. Under the condition that the nitrogen gas flow rate is the first flow rate, heat it at a heating rate of 1 - 5 °C / min to 180 - 185 °C, and then keep it warm for the first period of time. Then, raise the temperature to 195 °C, and increase the nitrogen gas flow rate to the second flow rate, and purge for the second period of time to blow off the excess iodine on the surface of the material. Finally, cool it to room temperature to obtain a carbon-rich coal gasification slag-based iodine-doped C / SiOx composite lithium battery anode material. During fumigation, the porous C / SiO x composite material is laid above the iodine. In Step 3, the first flow rate is 1 m / s, and the first period of time is 0.5 - 1.5 h; the second flow rate is 4 - 10 m / s, and the second period of time is 5 - 20 min.

2. Preparation method of carbon-rich coal gasification slag-based iodine-doped C / SiO x composite lithium battery anode material, characterized in that, In Step 1, the concentration of the nitric acid solution used is 2.0 mol / L; the dosage relationship between the carbon-rich gasification slag and the nitric acid solution is 1 g:8 mL; the soaking time is 36 h; after soaking and filtering, a solid residue and a waste liquid are obtained, then the solid residue is washed with distilled water until neutral, and then placed in a blast drying oven to dry to obtain a solid residue powder with metal impurities removed.

3. The preparation method of the carbon-rich gasification slag-based iodine-doped C / SiO x composite lithium battery anode material, characterized in that, In Step 2.1, the dosage relationship between the solid residue and the chemical activator is 1:2-6 by mass ratio; then the mixture is placed in deionized water and soaked in an oil bath at 70°C for 24 h; then, it is directly placed in a blast drying oven at 110°C and dried for 24 h to obtain a dry mixture.

4. The preparation method of the carbon-rich gasification slag-based iodine-doped C / SiO x composite lithium battery anode material, characterized in that, In Step 2.2, the dry mixture is placed in a tubular furnace with nitrogen as the protective gas for carbonization activation for 2 h.

5. The preparation method of the carbon-rich gasification slag-based iodine-doped C / SiO x composite lithium battery anode material, characterized in that, In Step 2.3, the concentration of the nitric acid solution used is 1 mol / L; the dosage relationship between the activation product and the nitric acid solution is 1 g:5 mL in terms of mass-to-volume ratio, and the soaking time is 24 h; then the solid is obtained by filtration, washed with distilled water until neutral, and dried in a blast drying oven at 110 °C to obtain porous C / SiO x composite material.

6. The preparation method of the carbon-rich gasification slag-based iodine-doped C / SiO x composite lithium battery anode material, characterized in that, All the waste liquids generated in Steps 1 to 3 are neutralized with potassium hydroxide, and then the metal hydroxide precipitate is removed by filtration to obtain liquid fertilizer.

7. Application of a carbon-rich gasification slag-based iodine-doped C / SiO x composite lithium battery anode material, characterized in that, The negative electrode material is used as the negative electrode material of a lithium battery.

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