Method for preparing a surface-modified high-compacted SiOx

Abstract

This invention discloses a surface-modified high-pressure SiO2 x The preparation method of this invention includes the following steps: preparation of a carbon layer precursor by controlling the reaction time to prepare spherical carbon layer precursors of different sizes; thorough mixing of the carbon layer precursor with a silicon source and aging of the mixed solution; filtration and washing of the reaction solution followed by drying in a vacuum drying oven, and then sintering under an inert atmosphere to obtain multilayer carbon-coated SiO2. x Materials; SiO2 prepared by the technical solution of this invention x The material has a higher compaction density, thus reducing matrix pulverization. Meanwhile, the SiO₂ prepared by this invention... x The number of carbon shell layers in the material can be controlled, suppressing volume changes during charging and discharging.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a surface-modified high-pressure SiO2. x Preparation method. Background Technology

[0002] Currently, the rapid growth of the new energy vehicle and energy storage markets presents significant challenges to the development of high-energy-density and high-cycle-performance lithium-ion batteries. Compared to traditional graphite anode materials, silicon-based materials have a higher theoretical capacity (3579 mAh / g). However, silicon undergoes severe volume changes during charging and discharging, leading to matrix fragmentation and the stripping of active materials from the electrode surface, resulting in rapid capacity decay of the battery. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a surface-modified high-pressure SiO₂. x Preparation method.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A surface-modified high-pressure SiO x The preparation method includes the following steps:

[0006] Step 1: Preparation of carbon layer precursor: Take carbon source and solvent, mix them and place them in a high-pressure reactor, and react them at a temperature of 150-230℃. After the reaction is completed, wash and dry the product to obtain carbon layer precursor. The reaction time is 1-7h.

[0007] Step 2: After thoroughly mixing the carbon layer precursor and silicon source obtained in Step 1, dissolve them in the mixed solution to obtain a silicon oxide intermediate. Then, age the silicon oxide intermediate in a water bath to obtain product A. The aging temperature is 20-50℃ and the aging time is 4-12h.

[0008] Step 3: Filter and wash product A until no free metal ions are found, and dry the filtered product in a vacuum drying oven to obtain product B;

[0009] Step 4: Sinter product B under an inert gas atmosphere and then cool to obtain high-compacted coated SiO₂. x Material.

[0010] Furthermore, in step 1, the carbon source is one or more of glucose, sucrose, chitin, pitch, lignin, and starch.

[0011] Furthermore, the solvent in step 1 is one or more of anhydrous ethanol, isopropanol, ethylene glycol, glycerol, N,N-dimethylformamide, oleylamine, and water.

[0012] Furthermore, in step 1, the mass ratio of carbon source to solvent is (1-3):(3-5).

[0013] Furthermore, in step 2, the silicon source is TEOS, nano-silicon powder, SiO2, or SiO2. x One or more of them.

[0014] Furthermore, in step 2, the mixed solution B is a mixture of water and anhydrous ethanol, wherein the mass ratio of water to anhydrous ethanol is (1-3):(3-1).

[0015] Furthermore, in step 2, the mass ratio of the carbon layer precursor, silicon source, and mixed solution is (0.5-5):(5-20):(20-60).

[0016] Furthermore, in step 3, the drying temperature is 60–100°C, and the drying time is 1–10 hours.

[0017] Furthermore, the inert gas A is any one of nitrogen, argon, or a mixture of nitrogen and argon.

[0018] Furthermore, in step 4, the sintering temperature is 700–1000℃, and the sintering time is 3–10 hours.

[0019] Furthermore, the heating rate of the sintering temperature in step 4 is 1–10 °C / min.

[0020] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0021] 1. By utilizing the different diffusion rates of metal ions in different solutions, the solvent composition can be adjusted to control the number of carbon layers. Simultaneously, by utilizing the Kendall effect, hollow nanoparticles can be further formed from carbon spheres and silicon sources, which have different diffusion rates, under high-temperature calcination. This further restricts the SiO₂ content during discharge. x The volume expands.

[0022] 2. Using the carbon source in this technical solution as template carbon spheres, spherical particles of varying sizes are prepared by controlling the reaction temperature. Under room temperature conditions, and by controlling the preparation process, SiO₂ is finally obtained. x The particle size is controllable and the particle size distribution is uniform, thus avoiding the agglomeration of materials. Attached Figure Description

[0023] Figure 1 The surface-modified high-pressure SiO2 of this invention x Process flow diagram of the preparation method.

[0024] Figure 2The surface-modified high-pressure SiO2 of this invention x A schematic diagram.

[0025] Figure 3 The surface-modified high-pressure SiO2 of this invention x The charge / discharge curves. Detailed Implementation

[0026] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0027] Example 1: Step 1: Preparation of carbon layer precursor: Dissolve 4 kg of sucrose in 20 L of deionized water, stir and disperse, then transfer to a high-pressure reactor, seal the high-pressure reactor, purge the air from the reactor with nitrogen for 30 minutes, heat the high-pressure reactor to 180 °C, and react for 2 hours. After the reaction is completed, wash and dry the obtained reactants to obtain the carbon layer precursor.

[0028] Step 2: The carbon layer precursor, silicon dioxide, and mixed solution (water and anhydrous ethanol in a mass ratio of 1:3) prepared in this embodiment are thoroughly mixed in a mass ratio of 1:20:40 to obtain a silicon dioxide intermediate. The silicon dioxide intermediate is placed in a water bath at 30°C and aged for 8 hours to obtain product A.

[0029] Step 3: Filter and wash the product A prepared in this embodiment until there are no free metal ions. Place the washed product in a vacuum drying oven and dry at 90°C for 3 hours to obtain product B.

[0030] Step 4: The product B obtained in this embodiment is placed into a sagger, and nitrogen is used as a protective gas. The sintering furnace is heated to 1000°C for 4 hours. After the sintering furnace is naturally cooled to room temperature, multilayer carbon-coated SiO2 is obtained. x Material.

[0031] Example 2: Step 1: Preparation of carbon layer precursor: Dissolve 5 kg of glucose in 20 L of deionized water, stir and disperse, transfer to a high-pressure reactor, seal the high-pressure reactor, purge the air in the reactor with nitrogen for 30 minutes, heat the high-pressure reactor to 200 °C, react for 2 hours, and after the reaction is completed, wash and dry the product to obtain carbon layer precursor.

[0032] Step 2: The carbon layer precursor, nano-silicon powder and mixed solution (water and anhydrous ethanol in a mass ratio of 1:1:1) prepared in this embodiment are thoroughly mixed in a mass ratio of 1:15:30 to obtain a silicon oxide intermediate. The silicon oxide intermediate is placed in a water bath at 25°C and aged for 6 hours to obtain product A.

[0033] Step 3: Filter and wash product A in this embodiment until no free metal ions are present. Place the washed material in a vacuum drying oven and dry at 90°C for 3 hours to obtain product B.

[0034] Step 4: The product B obtained in this embodiment is placed into a sagger, and nitrogen is used as a protective gas. The sintering furnace is heated to 900°C for 4 hours. After the sintering furnace is naturally cooled to room temperature, multilayer carbon-coated SiO2 is obtained. x Material.

[0035] Example 3: Step 1: Preparation of carbon layer precursor: 2 kg of starch was dissolved in 18 L of deionized water, stirred and dispersed, then transferred to a high-pressure reactor. The reactor was sealed, and nitrogen gas was purged for 30 minutes to purge the air from the reactor. The reactor was then heated to 150 °C and reacted for 2 hours. After the reaction was completed, the product was washed and dried to obtain the carbon layer precursor.

[0036] Step 2: The carbon layer precursor, silicon dioxide, and mixed solution (water and anhydrous ethanol in a mass ratio of 2:3) prepared in this embodiment are thoroughly mixed in a mass ratio of 4:5:20 to obtain a silicon dioxide intermediate. The silicon dioxide intermediate is placed in a water bath at 50°C and aged for 10 hours to obtain product A.

[0037] Step 3: Filter and wash the product A prepared in this embodiment until there are no free metal ions. Place the washed material in a vacuum drying oven and dry at 90°C for 3 hours to obtain product B.

[0038] Step 4: The product B obtained in this embodiment is placed into a sagger, and nitrogen is used as a protective gas. The sintering furnace is heated to 1100°C for 3 hours. After the sintering furnace is naturally cooled to room temperature, multilayer carbon-coated SiO2 is obtained. x Material.

[0039] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the mass ratio of the carbon layer precursor, silicon dioxide and the mixed solution (water and anhydrous ethanol in a mass ratio of 1:3) is 0.1:20:40.

[0040] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the mass ratio of the carbon layer precursor, silicon dioxide, and mixed solution (water and anhydrous ethanol in a mass ratio of 1:3) is 1:50:40.

[0041] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the reaction temperature of the reactor is 100°C.

[0042] Table 1 shows the SiO₂ prepared in each embodiment and comparative example. x The compaction density of the material and SiO x Test values ​​of material discharge capacity.

[0043] 0.1C discharge capacity (mAh / g) <![CDATA[Compaction density (g / cm 3 )]]> Example 1 710 1.73 Example 2 690 1.68 Example 3 670 1.63 Comparative Example 1 560 1.60 Comparative Example 2 512 1.58 Comparative Example 3 473 1.53

[0044] According to Table 1, the sucrose concentrations of the carbon layer precursors in Examples 1, 2, and 3 are 0.2 kg / L, 0.25 kg / L, and 0.11 kg / L, respectively; the reaction temperatures in the reactors are 180°C, 200°C, and 150°C, respectively; the mass ratios of the carbon layer precursor, silica, and mixed solution in step 2 of Examples 1, 2, and 3 are 1:20:40, 1:15:30, and 4:5:20, respectively; the aging temperatures and aging times are 30°C, 4 h, 25°C, 6 h, and 50°C, 10 h, respectively; the sintering temperatures in step 4 of Examples 1, 2, and 3 are 1000°C, 900°C, and 1100°C, respectively. Furthermore, the carbon and silicon source compositions in Examples 1, 2, and 3 are different, but as can be seen from the table above, SiO₂ in Examples 1, 2, and 3... x The discharge capacity and compaction density of the material fluctuate within the error range. Therefore, fluctuations in the above reaction conditions within the experimental minimum and threshold values ​​will not affect the SiO2 solution of this technical solution. x Material preparation;

[0045] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the mass ratio of the carbon layer precursor, silicon dioxide, and mixed solution (water and anhydrous ethanol in a mass ratio of 1:3) is 0.1:20:40. In Comparative Example 1, SiO x The discharge capacity is 560 mAh / g, and the compaction density is 1.60 g / cm³. 3 ;

[0046] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the mass ratio of the carbon layer precursor, silicon dioxide, and mixed solution (water and anhydrous ethanol in a mass ratio of 1:3) is 1:50:40. In Comparative Example 2, SiO₂... x The discharge capacity is 512 mAh / g, and the compaction density is 1.58 g / cm³. 3 ;

[0047] This technical solution utilizes the Kendall effect and the different diffusion rates of metal ions in different solutions to limit the SiO material's properties during discharge. xThe volume expansion of SiO2, as can be seen from Examples 1, 1, and 2, is affected by the mass ratio of the carbon layer precursor, silicon oxide, and the mixed solution. x Given the discharge amount and compaction density, the implementation range of this technical solution is the optimal implementation range.

[0048] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the reaction temperature of the reactor is 100℃. The discharge capacity of SiOx in Comparative Example 3 is 473mAh / g, and the compaction density is 1.53g / cm3. Depending on the carbon source, spherical particles of different sizes can be prepared by controlling the reaction temperature, thereby affecting the compaction density and discharge effect of SiOx. As can be seen from Example 1, the reaction temperature in the reactor of carbon spheres affects the compaction density and discharge effect of SiOx. The reaction temperature of this example is a suitable temperature range for preparing carbon layer precursors.

[0049] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A surface-modified high-pressure SiO2 x Preparation method, characterized in that: Includes the following steps: Step 1: Preparation of carbon layer precursor: Take carbon source and solvent, mix them and place them in a high-pressure reactor, and react them at a temperature of 150-230℃. After the reaction is completed, wash and dry the product to obtain carbon layer precursor. The reaction time is 1-7h. Step 2: After thoroughly mixing the carbon layer precursor and silicon source obtained in Step 1, dissolve them in the mixed solution to obtain a silicon oxide intermediate. Then, age the silicon oxide intermediate in a water bath to obtain product A. The aging temperature is 20-50℃ and the aging time is 4-12h. Step 3: Filter and wash product A until no free metal ions are found, and dry the filtered product in a vacuum drying oven to obtain product B; Step 4: Sinter product B under an inert gas atmosphere and then cool to obtain high-compacted coated SiO₂. x Material.

2. The surface-modified high-pressure SiO₂ according to claim 1 x Preparation method, characterized in that: In step 1, the carbon source is one or more of glucose, sucrose, chitin, pitch, lignin, and starch.

3. A surface-modified high-pressure SiO2 according to claim 1 x Preparation method, characterized in that: The solvent in step 1 is one or more of anhydrous ethanol, isopropanol, ethylene glycol, glycerol, N,N-dimethylformamide, oleylamine, and water.

4. A surface-modified high-pressure SiO2 according to claim 1 x Preparation method, characterized in that: In step 1, the mass ratio of carbon source to solvent is (1-3):(3-5).

5. A surface-modified high-pressure SiO2 according to claim 1 x Preparation method, characterized in that: In step 2, the silicon source is TEOS, nano-silicon powder, SiO2, or SiO2. x One or more of them.

6. A surface-modified high-pressure SiO2 according to claim 5 x Preparation method, characterized in that: The mixed solution in step 2 is a mixture of water and anhydrous ethanol, wherein the mass ratio of water to anhydrous ethanol is (1-3):(3-1).

7. A surface-modified high-pressure SiO2 according to claim 6 x Preparation method, characterized in that: In step 2, the mass ratio of the carbon layer precursor, silicon source, and mixed solution is (0.5-5):(5-20):(20-60).

8. A surface-modified high-pressure SiO2 according to claim 1 x Preparation method, characterized in that: In step 3, the drying temperature is 60–100℃ and the drying time is 1–10 hours.

9. A surface-modified high-pressure SiO2 according to claim 1 x Preparation method, characterized in that: The inert gas is any one of nitrogen, argon, or a mixture of nitrogen and argon.

10. A surface-modified high-pressure SiO2 according to claim 9 x Preparation method, characterized in that: In step 4, the sintering temperature is 700–1000℃, the sintering time is 3–10h, and the heating rate of the sintering temperature is 1–10℃ / min.

Images