A porous metal-doped silicon-oxygen composite material, its preparation method and its application

Abstract

This invention discloses a porous metal-doped silicon-oxygen composite material, its preparation method, and its application. The method involves uniformly dispersing an organometallic compound, an organic dispersing solvent, and an organometallic coupling agent, then adding silicon-oxygen material, followed by spray drying, high-temperature sintering, and secondary granulation to obtain the porous metal-doped silicon-oxygen composite material. This composite material reduces expansion and improves electronic conductivity by embedding silicon-oxygen into the porous metal. Compared with porous carbon and inorganic metals, porous metals are easier to disperse and have milder reaction conditions. Therefore, the resulting porous metal-doped silicon-oxygen composite material exhibits advantages such as high initial efficiency, good power performance, and low expansion when applied to lithium-ion batteries.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery material preparation, specifically a porous metal-doped silicon-oxygen composite material, its preparation method, and its application. Background Technology

[0002] Silicon-based materials expand significantly, resulting in substantial expansion forces in battery modules and reduced cycle performance. Measures to reduce this expansion include nano-sizing and the fabrication of porous silicon-based materials. However, these methods decrease electronic conductivity, affecting rate performance and reducing initial efficiency. Improving electronic conductivity primarily involves doping with highly conductive metals or metal oxides to fill pores and reduce electronic impedance. However, side reactions can occur between the metal or metal compound and the electrolyte, necessitating surface carbon coating to mitigate these reactions. Nevertheless, even directly carbon-coated materials exhibit poor structural stability during contraction and expansion. Summary of the Invention

[0003] To reduce the expansion of silicon-based materials, this invention provides a porous metal-doped silicon-oxygen composite material, which is made by using silicon-oxygen material (SiO2) x The silicon-oxygen composite material is embedded into porous metal to reduce expansion and improve electronic conductivity. Through granulation and coating, a porous metal-doped silicon-oxygen composite material is obtained. This composite material has the characteristics of low expansion and good power when applied to lithium-ion batteries.

[0004] The technical solution adopted in this invention is as follows:

[0005] A porous metal-doped silicon-oxygen composite material, comprising a porous metal oxide and a silicon-oxygen material (SiO2) embedded in the porous metal oxide. x The metal in the porous metal oxide is a conductive metal, such as aluminum, which is often used as a negative electrode material; the porous metal-doped silicon oxide composite material is coated with amorphous carbon.

[0006] Preferably, the porous metal-doped silicon oxide composite material has a particle size of 5-15 μm.

[0007] The preparation method of the above-mentioned porous metal-doped silicon-oxygen composite material includes the following steps:

[0008] Step S1:

[0009] After the organometallic compound, organic dispersant, and organometallic coupling agent are added to an organic solvent and dispersed evenly, a silicon oxide material is added and ultrasonically dispersed evenly, followed by spray drying to obtain an organometallic coated silicon oxide precursor material.

[0010] Step S2:

[0011] Weigh the organometal-coated silicon-oxygen precursor material and binder and mix them evenly. Then transfer them to a vertical granulation furnace, heat them to carbonize them, then heat them again and introduce carbon source gas to keep them warm. After that, cool them down to room temperature in an inert atmosphere and crush them to obtain a porous metal-doped silicon-oxygen composite material.

[0012] Preferably, in step S1, the mass ratio of organometallic compound: organic dispersant: organometallic coupling agent: organic solvent is (1-10):(0.5-2):(0.5-2):(100-500):100;

[0013] In step S2, the mass ratio of the organometallic coated silicon-oxygen precursor material to the binder is 100:(1-10).

[0014] Preferably, in step S1, the organometallic compound is one of aluminum 2,6-acetylacetonate, aluminum tert-butoxide, aluminum ethoxylate, aluminum trifluoroacetylpyruvate, aluminum sec-butoxylate, aluminum isopropoxylate, and aluminum bis(2-ethylhexanoate).

[0015] Preferably, in step S1, the organic dispersant is one of polyvinylpyrrolidone, polyamide, and silicone oil;

[0016] The organometallic coupling agent is one of the following: aluminate coupling agent, isopropyl tristearate titanate, diisopropoxydiacetylacetonate titanate, and diisopropoxydiacetylacetonate titanate.

[0017] The organic solvent is one of diethyl ether, diisopropyl ether, di-n-propyl ether, and di-n-butyl ether.

[0018] Preferably, in step S2, the binder is one of petroleum asphalt, coal tar pitch, or mesophase asphalt, with a softening point of 80-150℃.

[0019] Preferably, in step S2, after the organometallic coated silicon-oxygen precursor material and the binder are uniformly mixed and transferred to a vertical granulation furnace, the temperature is first raised to 200-400℃ for carbonization for 1-6 hours, and then the temperature is raised to 800-1100℃ and carbon source gas is introduced for heat preservation for 1-6 hours.

[0020] Preferably, in step S2, the carbon source gas is one of methane, ethane, acetylene, and ethylene.

[0021] The above-mentioned porous metal-doped silicon-oxygen composite materials are used in lithium-ion batteries.

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

[0023] A chemical method is used to mix silicon oxide with organometallic compounds, followed by granulation and carbonization. The carbonization of the organometallic compounds yields porous metal compounds. The silicon oxide material and the porous metal oxide are linked by chemical bonds, exhibiting structural stability and low impedance. Secondary granulation further reduces expansion. Simultaneously, high-temperature carbonization coats the outer layer with amorphous carbon, isolating the core metal and silicon oxide material from contact with the metal and electrolyte, reducing side reactions, and improving high-temperature storage performance. Attached Figure Description

[0024] Figure 1 The image shows a SEM image of the porous metal-doped silicon-oxygen composite material prepared in Example 1. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] Example 1

[0027] Step S1:

[0028] 5g of aluminum 2,6-acetylacetonate, 1g of polyvinylpyrrolidone, and 1g of aluminate coupling agent were added to 300g of carbon tetrachloride and dispersed evenly. Then, 100g of silicon suboxide was added, and the mixture was ultrasonically dispersed evenly. Finally, it was spray-dried to obtain an organometallic coated silicon oxide precursor material.

[0029] Step S2:

[0030] 100g of organometal-coated silicon-oxygen precursor material was weighed and mixed evenly with 5g of petroleum asphalt. Then, it was transferred to a vertical granulation furnace, heated to 300℃ for 3 hours, then heated to 950℃ and methane gas was introduced for 3 hours. After that, it was cooled to room temperature under an inert argon atmosphere and pulverized to obtain a porous metal-doped silicon-oxygen composite material.

[0031] Example 2

[0032] Step S1:

[0033] 1g of aluminum ethoxylate, 0.5g of polyamide, and 0.5g of isopropyl tristearate titanate were added to 100g of cyclohexane and dispersed evenly. Then, 100g of silica was added, and the mixture was ultrasonically dispersed evenly. Finally, it was spray-dried to obtain an organometallic coated silicon-oxygen precursor material.

[0034] Step S2:

[0035] Weigh 100g of organometal-coated silicon-oxygen precursor material and mix it evenly with 1g of coal tar pitch binder. Then transfer it to a vertical granulation furnace, first heat it to 200℃ for carbonization for 6h, then heat it to 800℃ and acetylene gas is introduced for 6h. After that, cool it down to room temperature in an inert argon atmosphere and pulverize it to obtain a porous metal-doped silicon-oxygen composite material.

[0036] Example 3

[0037] Step S1:

[0038] 10g of aluminum trifluoroacetylpyruvate, 2g of silicone oil, and 2g of isopropyl tristearate titanate were added to 500ml of N-methylpyrrolidone and dispersed evenly. Then, 100g of silica was added, and the mixture was ultrasonically dispersed evenly. After spray drying, organometallic coated silicon-oxygen precursor material was obtained.

[0039] Step S2:

[0040] 100g of organometal-coated silicon-oxygen precursor material and 10g of mesophase pitch binder were weighed and mixed evenly. The mixture was then transferred to a vertical granulation furnace. The furnace was first heated to 400℃ and carbonized for 1 hour. Then the temperature was increased to 1100℃ and carbon source gas was introduced and kept at that temperature for 1 hour. After that, the temperature was lowered to room temperature under an argon inert atmosphere and pulverized to obtain a porous metal-doped silicon-oxygen composite material.

[0041] Comparative Example 1:

[0042] The difference from Example 1 is that no porous metal treatment was formed on the surface of silicon suboxide.

[0043] Weigh 100g of silicon suboxide and mix it evenly with 5g of petroleum asphalt. Then transfer it to a vertical granulation furnace. First, heat it to 300℃ and carbonize it for 3 hours. Then heat it to 950℃ and introduce methane gas to keep it warm for 3 hours. Then cool it down to room temperature in an inert argon atmosphere and pulverize it to obtain carbon-coated silicon-oxygen composite material.

[0044] Comparative Example 2:

[0045] The difference from Example 1 is that the silicon-oxygen precursor material is obtained by directly mixing silicon suboxide and aluminum powder nanoparticles.

[0046] 0.42g of nano-aluminum powder and 100g of silicon suboxide were ultrasonically dispersed evenly in 300g of carbon tetrachloride and then spray-dried to obtain a metal-coated silicon-oxygen precursor material.

[0047] Step S2:

[0048] Weigh 100g of metal-coated silicon-oxygen precursor material and mix it evenly with 5g of petroleum asphalt. Then transfer it to a vertical granulation furnace, first heat it to 300℃ for carbonization for 3h, then heat it to 950℃ and introduce methane gas to keep it at that temperature for 3h, then cool it down to room temperature in an inert argon atmosphere and pulverize it to obtain a porous metal-doped silicon-oxygen composite material.

[0049] 1. SEM testing

[0050] The porous metal-doped silicon-oxygen composite material prepared in Example 1 was subjected to SEM testing, and the results are as follows: Figure 1 As shown, the porous metal-doped silicon-oxygen composite material prepared in Example 1 exhibits a granular structure with micropores on the surface, uniformly distributed in size, and a particle size of 5–15 μm.

[0051] 2. Physical and chemical properties and button cell testing

[0052] The porous metal-doped silicon-oxygen composite materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to particle size, tap density, specific surface area, elemental analysis (metal elements), and specific capacity tests. Test methods: National Standard GB / T-38823-2020 "Silicon-Carbon"; a four-probe analyzer was also used to test the electronic conductivity of the powder materials.

[0053] The porous metal-doped silicon oxide composite materials obtained in Examples 1-3 and Comparative Examples 1-2 were assembled into coin cells A1, A2, A3, B1, and B2, respectively. The preparation method was as follows: binder, conductive agent, and solvent were added to the negative electrode material, stirred and slurried, coated on copper foil, and dried and rolled to obtain the coin cells. The binder used was LA132 binder, the conductive agent was SP, and the negative electrode material was the porous metal-doped silicon-oxygen composite material prepared in Examples 1-3 and Comparative Examples 1-2, respectively. The solvent was double-distilled water, and the ratio was: negative electrode material: SP: LA132: double-distilled water = 95g: 1g: 4g: 220mL, and a negative electrode sheet was prepared. The electrolyte was LiPF6 / EC+DEC (volume ratio 1:1, concentration 1.3mol / L), the counter electrode was lithium metal sheet, and the separator was polyethylene (PE), polypropylene (PP), or polyethylene propylene (PEP) composite membrane. The simulated battery was assembled in an argon-filled glove box, and the electrochemical performance was tested on a Wuhan Landian CT2001A battery tester. The charge / discharge voltage range was 0.00V to 2.0V, and the charge / discharge rate was 0.1C. The rate capability (2C / 0.1C) and cycle performance (0.2C / 0.2C, 200 cycles) of the coin cell were also tested. The test results are shown in the table below.

[0054] Table 1

[0055] serial number project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 1 Particle size (D50, μm) 7.6 7.9 7.5 9.1 8.9 2 <![CDATA[Tap density (g / cm 3 )]]> 0.89 0.85 0.82 0.73 0.74 3 <![CDATA[Specific surface area (m2 / g)]]> 7.9 7.5 7.7 4.9 3.8 4 Silicon grain size (nm) 6.7 6.5 7.1 7.3 7.5 5 Powder conductivity (S / cm) 5.6 6.5 4.5 1.2 1.5 6 Metallic trace elements (rare earth elements) 4.8％ 5.9％ 3.3％ 4.6％ 4.5％ 7 Initial discharge capacity (mAh / g) 1650 1630 1660 1430 1390 8 First-time efficiency (%) 84.2 83.5 85.1 79.3 80.1 9 Rate performance (2C / 0.1C) 92.5 91.6 90.1 84.6 85.5 10 Cyclic performance (capacity retention) 93.1 92.6 92.4 86.3 87.1

[0056] As shown in Table 1, compared with the comparative example, the porous metal-doped silicon-oxygen composite materials prepared in Examples 1-3 exhibit significantly improved initial discharge capacity, initial efficiency, rate performance, and cycle performance. A comparison between Example 1 and Comparative Example 1 reveals that in this invention, by coating the surface of the silicon-oxygen material with a metal exhibiting high electronic conductivity, the electronic conductivity and specific capacity of the material are improved. Simultaneously, the porous metal has a high specific surface area, enhancing liquid absorption and improving cycle performance. A comparison between Example 1 and Comparative Example 2 shows that the coating with a directly surface-modified organometallic material effectively improves the coating effect on the silicon-oxygen material, resulting in a more uniform coating of the porous metal material. Its performance improvement effect on the battery material is superior to that of coating materials directly using metal nanoparticles.

[0057] 3. Soft-pack battery

[0058] The porous metal-doped silicon-oxygen composite materials prepared in Examples 1-3 and Comparative Examples 1-2 were used as negative electrode materials, and negative electrode sheets were prepared using ternary materials (LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 Using O2 as the positive electrode, LiPF6 (solvent EC+DEC, volume ratio 1:1, concentration 1.3mol / L) as the electrolyte, and Celegard 2400 as the separator, 5Ah soft-pack batteries C1, C2, C3 and D1, D2 were prepared, thus obtaining ternary lithium batteries. The following tests were conducted, and the test results are shown in Table 2.

[0059] Ratio performance

[0060] The rate performance of the soft-pack battery was tested with a charge / discharge voltage range of 2.5–4.2V and a temperature of 25±3.0℃. The batteries were charged at 1.0C, 3.0C, 5.0C, 10.0C, and 20.0C, and discharged at 1.0C. The results are shown in Table 2.

[0061] Table 2

[0062]

[0063] As can be seen from the table above, the rate charging performance of the pouch batteries in Examples 1-3 is significantly better than that of Comparative Examples 1-2. That is, the charging time of the pouch batteries in Examples 1-3 is shorter. The reason is that the materials in the examples have a high specific surface area and a low electronic impedance, which improves the lithium-ion insertion and extraction rate, thereby improving the rate performance.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A porous metal-doped silicon-oxygen composite material, characterized by, comprising a porous metal oxide and a silicon-oxygen material SiO embedded in the porous metal oxide x ; the metal in the porous metal oxide is an electrically conductive metal; the porous metal-doped silicon-oxygen composite is coated with an outer layer of amorphous carbon; The preparation method of the porous metal-doped silicon-oxygen composite material comprises the following steps: Step S1: After the organic metal compound, the organic dispersant, and the organic metal coupling agent are uniformly dispersed in the organic solvent, the silicon-oxygen material is uniformly dispersed by ultrasonic, and then spray drying is performed to obtain an organic metal-coated silicon-oxygen precursor material; The organic metal compound is one of 2,6-acetylacetone aluminum, tertiary butyl alcohol aluminum, ethoxy aluminum, aluminum trifluoroacetylacetate, sec-butoxy aluminum, isopropoxy aluminum, and bis(2-ethylhexanoate)hydroxy aluminum. The mass ratio of the organic metal compound, the organic dispersant, the organic metal coupling agent, the organic solvent, and the silicon-oxygen material is (1-10):(0.5-2):(0.5-2):(100-500):

100. Step S2: The organic metal-coated silicon-oxygen precursor material and the binder are weighed and uniformly mixed, and then transferred to a vertical granulating furnace, carbonized by heating, then heated and carbon source gas is introduced for heat preservation, then cooled to room temperature in an inert atmosphere, and then crushed to obtain a porous metal-doped silicon-oxygen composite material. The mass ratio of the organic metal-coated silicon-oxygen precursor material and the binder is 100:(1-10).

2. The porous metal-doped silicon-oxygen composite of claim 1, wherein, The particle size of the porous metal-doped silicon-oxygen composite material is 5-15 µm.

3. The porous metal-doped silicon-oxygen composite of claim 1, wherein, In step S1, the organic dispersant is one of polyvinylpyrrolidone, polyamide, and silicone oil. The organic metal coupling agent is one of aluminate coupling agent, triisopropyl titanate, triisopropyl titanate, diisopropoxy diacetylacetone titanate, and diisopropoxy diacetylacetone titanate. The organic solvent is one of diethyl ether, diisopropyl ether, di-n-propyl ether, and di-n-butyl ether.

4. The porous metal-doped silicon-oxygen composite of claim 1, wherein, In step S2, the binder is one of petroleum pitch, coal tar pitch, and mesophase pitch, and the softening point is 80-150°C.

5. The porous metal-doped silicon-oxygen composite of claim 1, wherein, In step S2, after the organic metal-coated silicon-oxygen precursor material and the binder are uniformly mixed and transferred to the vertical granulating furnace, the temperature is first raised to 200-400°C for carbonization for 1-6 h, and then the temperature is raised to 800-1100°C and carbon source gas is introduced for heat preservation for 1-6 h.

6. The porous metal-doped silicon-oxygen composite material of claim 1, wherein, In step S2, the carbon source gas is one of methane, ethane, acetylene, and ethylene.

7. The porous metal-doped silicon-oxygen composite material according to any one of claims 1-6 is used in a lithium ion battery.

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