A modified silicon oxide battery negative electrode composite material and its preparation method and application

Abstract

The invention discloses a modified silicon oxide battery negative electrode composite material and a preparation method and application thereof, belonging to the technical field of lithium ion battery preparation, comprising the following steps: irradiating silicon oxide powder with an electron beam to form ablated silicon oxide powder with a rough surface, a large specific surface area and multiple pores, which can accommodate more lithium ions for embedding and de-embedding, thereby improving the initial efficiency; uniformly loading lithium ions on the surface, and wrapping the surface with a dense carbonized layer, thereby further alleviating the volume effect in the electrochemical reaction; effectively reducing the contact with the electrolyte, and stabilizing the SEI layer; introducing pyrene groups into acrylic acid monomers, and after being modified with stearic acid, a certain rigidity can be given to the binder, and the binder still has excellent mechanical stability when suppressing the volume expansion of silicon oxide. When the binder contacts the surface of the carbonized layer, the binder can penetrate into the pores and form a closer contact with the carbonized layer, thereby helping to improve the bonding strength and further preventing damage and shedding.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery preparation technology, specifically relating to a modified silicon suboxide battery anode composite material, its preparation method, and its application. Background Technology

[0002] Silicon anode materials possess extremely high theoretical capacity, a superior characteristic that endows them with higher energy storage capabilities, thereby effectively improving battery range or the overall energy density of energy storage systems. It is worth noting that electrons within silicon crystals are tightly bound to atoms by strong covalent bonds, making free movement difficult. This results in relatively poor conductivity of silicon materials. Furthermore, the lithium intercalation process involves alloying reactions, which are accompanied by significant volume changes during battery charge-discharge cycles.

[0003] Chinese patent application CN112678807B discloses a modified silicon suboxide / carbon nanotube composite anode material and its preparation method. It uses a silane coupling agent to chemically react with silicon-based material particles and polymerize on the surface, forming a special three-dimensional structure with carbon nanotube granulation. However, the silane coupling agent has a low degree of polymerization, short molecular chains, and weak intermolecular interaction forces, which cannot effectively alleviate the volume expansion of the anode material.

[0004] Chinese patent application CN116632234A discloses a binder for lithium battery anode materials and its preparation method. The binder, prepared using butadiene compounds, styrene compounds, and polyacrylonitrile, exhibits excellent wetting effect on the anode material and can achieve good adhesion with it. Furthermore, it uses propylene sulfite as a film-forming additive, which has good compatibility with the matrix emulsion, forming a uniform and stable system. However, when faced with the expansion of the anode material, the binder is not strong enough and is prone to detachment. Summary of the Invention

[0005] The purpose of this invention is to provide a modified silicon suboxide battery anode composite material. By irradiating silicon suboxide powder with an electron beam, a porous structure with a rough surface and a large specific surface area is formed. Lithium ions are uniformly loaded on the surface, and after carbonization of the covalent coating layer generated in situ on the surface, a dense carbonized layer is formed, which has good strength and can effectively alleviate the stress caused by volume change. By introducing pyrene groups into the acrylic monomer and modifying it with stearic acid, a certain rigidity can be given to the binder. It still has excellent mechanical stability while suppressing the volume expansion of silicon suboxide, thereby avoiding damage and detachment of the binder.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A modified silicon suboxide anode composite material for solar cells is prepared by the following steps:

[0008] Step 1: Place 100-120nm silicon suboxide powder in a stainless steel housing (outer diameter 28-30mm, height 3-4mm, housing thickness 0.3-0.32mm). Place the housing in the center of the mold and press the silicon suboxide powder into the housing using a tablet press at a pressure of 5-6MPa. Place the housing containing the silicon suboxide powder on the electron beam stage, start the equipment and turn on the vacuum system. When the vacuum degree of the vacuum chamber reaches 6.5×10⁻⁶... -3 At Pa, the accelerating voltage is 25-28 kV, the pulse duration is 2-4 μs, and the resulting irradiation energy is 2.2-2.5 J / cm². 2 The electron beam directly irradiates silicon suboxide powder to obtain ablated silicon suboxide powder.

[0009] Step 2: Add ablation silica powder and 5-7% sodium hydroxide solution to a reaction vessel, stir for 40-60 min at 80-90℃ and 500-600 r / min, allow to cool naturally, filter, wash the filter cake with deionized water until the final washing liquid is neutral, and vacuum dry at 60-80℃ for 1-2 h to obtain modified silica powder; add ethyl p-aminobenzoate and modified silica powder to a reaction vessel, stir for 1-2 h at 50-60℃ and 500-600 r / min, add lithium sulfate and deionized water to the reaction vessel, continue stirring for 1-2 h, filter, wash the filter cake 2-3 times with anhydrous ethanol, and vacuum dry at 60-80℃ for 1-2 h to obtain composite silica powder.

[0010] Step 3: Add the composite silicon suboxide powder, 2,5-diaminobenzoic acid, and deionized water to a reaction vessel and stir for 40-45 min at 50-60℃ and 500-700 r / min. Add tetra(4-aldehydephenyl)ethylene to the reaction vessel and stir for 10-12 min at 20-25℃ and 500-600 r / min. Add dimethylacetamide, N,N-dimethylformamide, and a 4 mol / L acetic acid solution to the reaction vessel and continue the reaction for 1-2 h. Filter the mixture and wash the filter cake 2-3 times with deionized water. Vacuum dry at 60-80℃ for 1-2 h to obtain the precursor powder. Place the precursor powder in a muffle furnace and heat it at 950-1000℃ for 2-3 h under nitrogen protection to carbonize the organic matter in the precursor powder. Allow it to cool naturally to obtain the modified silicon suboxide anode substrate material.

[0011] Step 4: Add 1,3,6,8-tetra(4-formaldehydephenyl)-pyrene, sodium borohydride, and deionized water to a reaction vessel. Stir for 40-60 minutes at 70-80℃ and 500-600 rpm. Filter and wash the filter cake with tetrahydrofuran 2-3 times to obtain the reduced product. Add the reduced product, an acrylic acid solution with a neutralization degree of 65-70%, and deionized water to the reaction vessel. Stir for 40-60 minutes at 70-80℃ and 500-600 rpm. Then add stearic acid to the reaction vessel and stir at 50-60℃ and 500-600 rpm. Stirring under incubation conditions for 1-2 hours, cooling to 55-65℃, adding sodium sulfite as an initiator, an acrylic acid solution with a neutralization degree of 65-70%, and hydroxymethylacrylamide as a crosslinking agent to the reactor, purging with nitrogen, heating to 70-80℃, stirring at 500-600 r / min for 3-4 hours, filtering, washing the filter cake 2-3 times with anhydrous ethanol, and vacuum drying at 60-80℃ for 1-2 hours to obtain the modified binder; mixing the modified silicon suboxide anode substrate material and the modified binder at a mass ratio of 8:1 to obtain the modified silicon suboxide battery anode composite material.

[0012] Furthermore, in step two, the ratio of ablation silica powder to sodium hydroxide solution is 10-12g: 500-600mL.

[0013] Furthermore, in step two, the ratio of ethyl p-aminobenzoate, modified silica powder, lithium sulfate, and deionized water is 200-300 mL: 5-6 g: 3-4 g: 400-500 mL.

[0014] Furthermore, in step three, the ratio of the amount of composite silica powder, 2,5-diaminobenzoic acid, deionized water, tetra(4-aldehydephenyl)ethylene, dimethylacetamide, N,N-dimethylformamide, and acetic acid solution is 4-5g: 8-9g: 400-500mL: 8-9g: 10-12mL: 10-12mL: 5-6mL.

[0015] Furthermore, in step four, the ratio of 1,3,6,8-tetra(4-formaldehydephenyl)-pyrene, sodium borohydride, and deionized water is 7-9g:30-40g:300-400mL.

[0016] Furthermore, in step four, the ratio of the reducing agent, acrylic acid solution, deionized water, stearic acid, sodium sulfite, and hydroxymethylacrylamide is 5-6g: 80-90mL: 200-300mL: 20-30g: 80-100mL: 80-100mL.

[0017] This invention also provides an application of a modified silicon suboxide battery anode composite material in the preparation of a lithium battery anode.

[0018] The beneficial effects of this invention are:

[0019] 1. The modified silicon suboxide battery anode composite material of the present invention is prepared by modifying the silicon suboxide anode substrate material and the modified binder. In the application of lithium battery anodes, it can effectively alleviate the stress caused by volume changes and maintain the structural integrity of the silicon suboxide anode material during charging and discharging. The carbonized layer encapsulates lithium elements inside, effectively reducing the occurrence of side reactions and stabilizing the SEI layer (solid electrolyte interface layer). The modified binder has good adhesion and strength, which can prevent the anode material from being damaged and falling off.

[0020] 2. The modified silicon suboxide anode substrate material of the present invention, through electron beam irradiation of silicon suboxide powder, forms a porous structure with a rough surface and a large specific surface area, which is beneficial to the diffusion of lithium ions and the transport of electrons. The rough porous structure can effectively alleviate volume expansion. Lithium atoms are loaded onto the surface of the ablated silicon suboxide powder by using ethyl p-aminobenzoate as a bridge, and a covalent encapsulation layer with a certain strength is generated in situ on its surface. After high-temperature carbonization, a dense carbonized layer is formed, which helps to better avoid the volume expansion effect and encapsulate the lithium element inside, effectively reducing contact with the electrolyte, thereby reducing the occurrence of side reactions, stabilizing the SEI layer, avoiding excessive consumption of lithium ions, and improving the first cycle coulombic efficiency.

[0021] 3. The modified binder of the present invention is generated by polymerizing pyrene groups into acrylic monomers and modifying them with stearic acid. Pyrene groups are rigid groups, which endow the binder with a certain rigidity and maintain excellent mechanical stability while suppressing the volume expansion of silicon suboxide. They can also improve the transport of charge carriers, which helps to improve the overall electronic conductivity of the negative electrode material and improve the rate performance of the battery. Through the modification of stearic acid, the mobility of polymer chain segments is increased, which helps to avoid the problem of reduced flexibility of the binder caused by the introduction of rigid groups, thereby preventing the binder from being damaged and falling off. The dense carbonized layer has a certain porous structure, which provides channels for the binder to penetrate and diffuse. When the binder comes into contact with the surface of the carbonized layer, it can penetrate into the pores and form a tighter contact with the carbonized layer, which helps to improve the bonding strength and further prevent damage and falling off. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: A modified silicon suboxide anode composite material for solar cells, prepared through the following steps:

[0024] S1: Place 100-120nm silicon suboxide powder in a stainless steel shell (outer diameter 28mm, height 3mm, shell thickness 0.3mm). Place the shell in the center of the mold and press the silicon suboxide powder into the shell using a tablet press at a pressure of 5MPa. Place the shell containing the silicon suboxide powder on the electron beam stage, start the equipment and turn on the vacuum system. When the vacuum degree of the vacuum chamber reaches 6.5×10⁻⁶... -3 At Pa, with an accelerating voltage of 25 kV and a pulse duration of 2 μs, the resulting irradiation energy is 2.2 J / cm². 2 The electron beam directly irradiates silicon suboxide powder to obtain ablated silicon suboxide powder.

[0025] Electron beam irradiation raises the surface temperature above the melting point of silicon suboxide, causing the silicon suboxide structure to ablate and form a porous structure with a rough surface and a large specific surface area. This is beneficial for the diffusion of lithium ions and the transport of electrons. During the charging and discharging process of lithium-ion batteries, the negative electrode material will undergo volume expansion and contraction. The porous silicon suboxide negative electrode material can buffer this volume change through its porosity, thereby maintaining the stability of the electrode structure.

[0026] S2: Add 10g of ablated silica powder and 500mL of 5% sodium hydroxide solution to a reactor. Stir at 80℃ and 500r / min for 40min, allow to cool naturally, filter, and wash the filter cake with deionized water until the final washing liquid is neutral. Dry under vacuum at 60℃ for 1h to obtain modified silica powder. Add 200mL of ethyl p-aminobenzoate and 5g of modified silica powder to a reactor. Stir at 50℃ and 500r / min for 1h. Add 3g of lithium sulfate and 400mL of deionized water to the reactor and continue stirring for 1h. Filter, wash the filter cake twice with anhydrous ethanol, and dry under vacuum at 60℃ for 1h to obtain composite silica powder.

[0027] After treatment with sodium hydroxide, hydroxyl groups are formed on the surface of the ablated silicon suboxide powder and react with the amino group of ethyl p-aminobenzoate. Under the action of hydrolysis, carboxyl groups are exposed and coordinate with lithium ions, thereby uniformly loading lithium ions onto the surface of the ablated silicon suboxide powder.

[0028] S3: Add 4g of composite silicon suboxide powder, 8g of 2,5-diaminobenzoic acid, and 400mL of deionized water to a reaction vessel and stir for 40min at 50℃ and 500r / min. Add 8g of tetrakis(4-aldehydephenyl)ethylene to the reaction vessel and stir for 10min at 20℃ and 500r / min. Add 10mL of dimethylacetamide, 10mL of N,N-dimethylformamide, and 5mL of 4mol / L acetic acid solution to the reaction vessel and continue the reaction for 1h. Filter the mixture and wash the filter cake twice with deionized water. Dry the filter cake under vacuum at 60℃ for 1h to obtain the precursor powder. Place the precursor powder in a muffle furnace and heat it at 950℃ for 2h under nitrogen protection to carbonize the organic matter in the precursor powder. Allow it to cool naturally to obtain the modified silicon suboxide anode substrate material.

[0029] The remaining hydroxyl groups on the surface of the composite silica powder are chemically bonded to the carboxyl groups of 2,5-diaminobenzoic acid, and then reacted with tetra(4-aldehydephenyl)ethylene to form a covalent coating layer with a certain strength. After carbonization, a dense carbonized layer is formed on the surface of the silica powder. The carbonized layer encapsulates the lithium element inside, effectively reducing contact with the electrolyte, thereby reducing the occurrence of side reactions, stabilizing the SEI layer (solid electrolyte interface layer), avoiding excessive consumption of lithium ions, and reducing irreversible capacity loss.

[0030] S4: Add 7g of 1,3,6,8-tetrakis(4-formaldehydephenyl)-pyrene, 30g of sodium borohydride, and 300mL of deionized water to a reaction vessel. Stir at 70℃ and 500r / min for 40min, filter, and wash the filter cake twice with tetrahydrofuran to obtain the reduced product. Add 5g of the reduced product, 80mL of acrylic acid solution with a neutralization degree of 65%, and 200mL of deionized water to a reaction vessel. Stir at 70℃ and 500r / min for 40min, then... 20g of stearic acid was added to a reaction vessel and stirred for 1 hour at 50℃ and 500r / min. After cooling to 55℃, 80mL of sodium sulfite as an initiator, 80mL of acrylic acid solution with a neutralization degree of 65% and 80mL of hydroxymethylacrylamide as a crosslinking agent were added to the reaction vessel. Nitrogen gas was introduced for protection, and the mixture was heated to 70℃ and stirred at 500r / min for 3 hours. The mixture was filtered, and the filter cake was washed twice with anhydrous ethanol and dried under vacuum at 60℃ for 1 hour to obtain the modified binder.

[0031] The aldehyde group is reduced to a hydroxyl group by sodium borohydride, and the pyrene group is introduced into the acrylic monomer for polymerization. After modification with stearic acid, a modified binder is obtained. The pyrene group is a rigid group, which gives the binder a certain rigidity, ensuring that the modified binder still has excellent mechanical stability while suppressing the volume expansion of silicon suboxide, and can improve the transport of charge carriers, which helps to improve the overall electronic conductivity of the substrate material and improve the rate performance of the battery. The introduction of rigid groups usually leads to a decrease in the flexibility of polymer chain segments. The large steric hindrance of rigid groups makes it difficult for polymer chain segments to deform under external force, thus reducing the flexibility of the material. By grafting stearic acid to increase the mobility of polymer chain segments, the material is more likely to deform under external force, thereby improving flexibility and helping to prevent damage and detachment of the substrate material.

[0032] S5: The modified silicon suboxide anode substrate material and the modified binder are mixed evenly at a mass ratio of 8:1 to obtain the modified silicon suboxide battery anode composite material.

[0033] Example 2: A modified silicon suboxide anode composite material for solar cells, prepared through the following steps:

[0034] S1: Place 100-120nm silicon suboxide powder in a stainless steel shell (outer diameter 29mm, height 3.5mm, shell thickness 0.31mm). Place the shell in the center of the mold and press the silicon suboxide powder into the shell using a tablet press at a pressure of 5MPa. Place the shell containing the silicon suboxide powder on the electron beam stage, start the equipment and turn on the vacuum system. When the vacuum degree of the vacuum chamber reaches 6.5×10⁻⁶... -3 At Pa, with an accelerating voltage of 27 kV and a pulse duration of 3 μs, the resulting irradiation energy is 2.3 J / cm². 2 The electron beam directly irradiates silicon suboxide powder to obtain ablated silicon suboxide powder.

[0035] S2: 11g of ablated silica powder and 550mL of 6% sodium hydroxide solution were added to a reaction vessel and stirred at 85℃ and 550r / min for 50min. After natural cooling, the mixture was filtered, and the filter cake was washed with deionized water until the final washing liquid was neutral. The mixture was then vacuum dried at 70℃ for 1.5h to obtain modified silica powder. 250mL of ethyl p-aminobenzoate and 5.5g of modified silica powder were added to a reaction vessel and stirred at 55℃ and 550r / min for 1.5h. 3.5g of lithium sulfate and 450mL of deionized water were added to the reaction vessel, and stirring was continued for 1.5h. The mixture was then filtered, and the filter cake was washed three times with anhydrous ethanol. The mixture was then vacuum dried at 70℃ for 1.5h to obtain composite silica powder.

[0036] S3: Add 4.5g of composite silicon suboxide powder, 8.5g of 2,5-diaminobenzoic acid, and 450mL of deionized water to a reaction vessel and stir for 43min at 55℃ and 600r / min. Add 8.5g of tetrakis(4-aldehydephenyl)ethylene to the reaction vessel and stir for 11min at 23℃ and 550r / min. Add 11mL of dimethylacetamide, 11mL of N,N-dimethylformamide, and 5.5mL of 4mol / L acetic acid solution to the reaction vessel and continue the reaction for 1.5h. Filter the mixture, wash the filter cake three times with deionized water, and vacuum dry at 70℃ for 1.5h to obtain precursor powder. Place the precursor powder in a muffle furnace and heat at 980℃ for 2.5h under nitrogen protection to carbonize the organic matter in the precursor powder. Allow it to cool naturally to obtain the modified silicon suboxide anode substrate material.

[0037] S4: Add 8g of 1,3,6,8-tetra(4-formaldehydephenyl)-pyrene, 35g of sodium borohydride, and 350mL of deionized water to a reaction vessel. Stir for 50min at 78℃ and 550r / min, filter, and wash the filter cake with tetrahydrofuran three times to obtain the reduced product. Add 5.5g of the reduced product, 85mL of acrylic acid solution with a neutralization degree of 68%, and 250mL of deionized water to a reaction vessel. Stir for 50min at 78℃ and 550r / min, then add 25g of... Stearic acid was added to a reaction vessel and stirred at 55°C and 550 r / min for 1.5 h. After cooling to 60°C, 90 mL of sodium sulfite as an initiator, 85 mL of acrylic acid solution with a neutralization degree of 68%, and 90 mL of hydroxymethylacrylamide as a crosslinking agent were added to the reaction vessel. Nitrogen gas was introduced for protection, and the mixture was heated to 75°C and stirred at 550 r / min for 3.5 h. The mixture was then filtered, and the filter cake was washed three times with anhydrous ethanol and dried under vacuum at 70°C for 1.5 h to obtain the modified binder.

[0038] S5: The modified silicon suboxide anode substrate material and the modified binder are mixed evenly at a mass ratio of 8:1 to obtain the modified silicon suboxide battery anode composite material.

[0039] Example 3: A modified silicon suboxide anode composite material for solar cells, prepared through the following steps:

[0040] S1: Place 100-120nm silicon suboxide powder in a stainless steel shell (outer diameter 30mm, height 4mm, shell thickness 0.32mm). Place the shell in the center of the mold and press the silicon suboxide powder into the shell using a tablet press at a pressure of 6MPa. Place the shell containing the silicon suboxide powder on the electron beam stage, start the equipment and turn on the vacuum system. When the vacuum degree of the vacuum chamber reaches 6.5×10⁻⁶... -3At Pa, with an accelerating voltage of 28 kV and a pulse duration of 4 μs, the resulting irradiation energy is 2.5 J / cm². 2 The electron beam directly irradiates silicon suboxide powder to obtain ablated silicon suboxide powder.

[0041] S2: 12g of ablated silica powder and 600mL of 7% sodium hydroxide solution were added to a reaction vessel and stirred at 90℃ and 600r / min for 60min. After natural cooling, the mixture was filtered, and the filter cake was washed with deionized water until the final washing liquid was neutral. The mixture was then vacuum dried at 80℃ for 2h to obtain modified silica powder. 300mL of ethyl p-aminobenzoate and 6g of modified silica powder were added to a reaction vessel and stirred at 60℃ and 600r / min for 2h. 4g of lithium sulfate and 500mL of deionized water were added to the reaction vessel, and the mixture was stirred for another 2h. The mixture was filtered, and the filter cake was washed three times with anhydrous ethanol and vacuum dried at 80℃ for 2h to obtain composite silica powder.

[0042] S3: Add 5g of composite silicon suboxide powder, 9g of 2,5-diaminobenzoic acid, and 500mL of deionized water to a reaction vessel and stir for 45min at 60℃ and 700r / min. Add 9g of tetrakis(4-aldehydephenyl)ethylene to the reaction vessel and stir for 12min at 25℃ and 600r / min. Add 12mL of dimethylacetamide, 12mL of N,N-dimethylformamide, and 6mL of 4mol / L acetic acid solution to the reaction vessel and continue the reaction for 2h. Filter the mixture, wash the filter cake three times with deionized water, and vacuum dry it at 80℃ for 2h to obtain the precursor powder. Place the precursor powder in a muffle furnace and heat it at 1000℃ for 3h under nitrogen protection to carbonize the organic matter in the precursor powder. Allow it to cool naturally to obtain the modified silicon suboxide anode substrate material.

[0043] S4: Add 9g of 1,3,6,8-tetra(4-formaldehydephenyl)-pyrene, 40g of sodium borohydride, and 400mL of deionized water to a reaction vessel. Stir at 80℃ and 600r / min for 60min, filter, and wash the filter cake with tetrahydrofuran three times to obtain the reduced product. Add 6g of the reduced product, 90mL of acrylic acid solution with a neutralization degree of 70%, and 300mL of deionized water to a reaction vessel. Stir at 80℃ and 600r / min for 60min, and then add 3g of... 0 g of stearic acid was added to a reaction vessel and stirred for 2 h at 60 °C and 600 r / min. After cooling to 65 °C, 100 mL of sodium sulfite as an initiator, 90 mL of acrylic acid solution with a neutralization degree of 70% and 100 mL of hydroxymethylacrylamide as a crosslinking agent were added to the reaction vessel. Nitrogen gas was introduced for protection, and the mixture was heated to 80 °C and stirred at 600 r / min for 4 h. After filtration, the filter cake was washed three times with anhydrous ethanol and dried under vacuum at 80 °C for 2 h to obtain the modified binder.

[0044] S5: The modified silicon suboxide anode substrate material and the modified binder are mixed evenly at a mass ratio of 8:1 to obtain the modified silicon suboxide battery anode composite material.

[0045] Comparative Example 1: Based on Example 3, the ablation silicon suboxide powder in step S2 was replaced with silicon suboxide powder (particle size of 100-120 nm) in step S1, while the other steps remained unchanged, and a modified silicon suboxide battery anode composite material was prepared.

[0046] Comparative Example 2: Based on Example 3, ethyl p-aminobenzoate was omitted in step S2, while the remaining steps remained unchanged, to prepare a modified silicon suboxide battery anode composite material.

[0047] Comparative Example 3: Based on Example 3, 1,3,6,8-tetra(4-formaldehydephenyl)-pyrene was removed in step S4, while the remaining steps remained unchanged, and a modified silicon suboxide battery anode composite material was prepared.

[0048] Comparative Example 4: Based on Example 3, stearic acid was omitted in step S4, while the remaining steps remained unchanged, and a modified silicon suboxide battery anode composite material was prepared.

[0049] In the examples and comparative examples:

[0050] The electron beam device is model HOPE-I.

[0051] The silicon suboxide powder was purchased from Hengshui Crystal Rock New Energy Technology Co., Ltd.

[0052] Tetra(4-aldehydephenyl)ethylene was purchased from Guangzhou Jiatu Technology Co., Ltd.

[0053] 1,3,6,8-Tetra(4-formaldehydephenyl)-pyrene was purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0054] Ethyl p-aminobenzoate, lithium sulfate, 2,5-diaminobenzoic acid, dimethylacetamide, N,N-dimethylformamide, acetic acid, hydroxymethylacrylamide, sodium sulfite, and sodium borohydride were all purchased from Sigma-Aldrich.

[0055] The modified silicon suboxide battery anode composite materials prepared in Examples 1-3 and Comparative Examples 1-4 were placed in a resistivity tester and the pressure was set to 20 MPa for powder resistivity testing.

[0056] The prepared negative electrode composite material was cut into 15mm×20mm sizes. The negative electrode composite material was attached to the electrode surface on one side and to the steel plate on the other side using 3M pressure-sensitive adhesive (model VHB). The steel plate and the electrode were then fixed on a tensile fixture. The negative electrode sheet to be tested was stretched at a certain speed and a 180-degree peel test was performed. When the conductive current collector was completely peeled off, the detected data was the peel force (N / m).

[0057] Modified silicon suboxide battery negative electrode composite material and conductive carbon black were added to 400 mL of deionized water at a mass ratio of 8:1. The slurry was uniformly dispersed using a homogenizer at a speed of 700 r / min. Then, the slurry was uniformly coated on copper foil using a pusher and dried in a vacuum oven at 120 °C for 14 h to prepare the working electrode. A lithium sheet was used as the counter electrode, a glass fiber membrane (purchased from Whatman, UK) was used as the separator, and 1 mol / L lithium tetrafluoroborate (solvent being methoxyethane and ethylene carbonate in a volume ratio of 1:1) was used as the electrolyte. 1% vinylene carbonate and 5% fluoroethylene carbonate were added to the electrolyte. The cells were assembled into a coin cell in an argon-atmosphere inert gas glove box from Braun, Germany.

[0058] An in-situ volume monitor (GVM2200) was used to monitor the volume changes of the battery in real time during charging and discharging. The button cell battery charging and discharging tests were conducted on the LAND battery testing system of Wuhan Jinno Electronics Co., Ltd., using constant current charging and discharging tests. The measured voltage range was 0.005-2V, with the first cycle at 0.02C (1C=4200mAg). -1 Activation was performed at a low current density, followed by long-cycle performance testing at a current density of 0.1C. The performance test results of the modified silicon suboxide battery anode composite material are shown in Table 1.

[0059] Table 1 Performance test results of modified silicon suboxide battery anode composite material

[0060]

[0061] As shown in Table 1, the volume change percentage of the modified silicon suboxide battery anode composite material prepared in Examples 1-3 of this invention is significantly lower than that of the comparative example. The initial efficiency, conductivity, and peel strength are significantly higher than those of the comparative example. In Comparative Example 1, replacing the ablation silicon suboxide powder with silicon suboxide powder results in the loss of surface roughness, large specific surface area, and porous characteristics. This prevents lithium ions from being distributed more evenly inside the material, thereby exacerbating the local stress concentration caused by uneven lithium ion insertion. Furthermore, it fails to provide more active sites for lithium ion insertion and extraction, thus reducing the initial efficiency. The loss of the porous structure also prevents the provision of additional space for the volume expansion of silicon suboxide, reducing the direct contact area with the electrolyte and resulting in fewer transport channels for electrons and ions between the materials, thereby reducing the conductivity.

[0062] In Comparative Example 2, the absence of ethyl para-aminobenzoate resulted in lithium atoms not being able to be stably and uniformly loaded on the silicon suboxide surface, hindering their insertion and extraction. This led to some areas having excessively high lithium-ion concentrations and others having insufficient concentrations during the initial lithium insertion process. The high-concentration lithium-ion regions were prone to side reactions, forming irreversible inert substances, thereby reducing the initial efficiency. If lithium atoms could not be inserted and extracted from silicon suboxide effectively, the lithium-ion diffusion path would be blocked, leading to an increase in the battery's internal resistance and a decrease in conductivity.

[0063] In Comparative Example 3, the absence of 1,3,6,8-tetra(4-formaldehydephenyl)-pyrene resulted in the lack of pyrene groups in the modified binder. Consequently, the rigidity and strength of the modified binder could not be improved, and it could not help alleviate volume changes. Furthermore, the pyrene group can enhance carrier transport, which helps improve the overall electronic conductivity of the negative electrode material and improve the rate performance of the battery. However, this also reduces conductivity, leading to an increase in the battery's internal resistance and obstruction of the lithium-ion diffusion path, thus affecting the initial efficiency. When suppressing the volume expansion of silicon suboxide, the modified binder lacks sufficient strength to maintain stability, making it prone to peeling off from the negative electrode material.

[0064] In Comparative Example 4, the absence of stearic acid would result in excessively high rigidity of the modified adhesive, leading to a decrease in flexibility and thus preventing the adhesive from being damaged and falling off.

[0065] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0066] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a modified silicon oxide battery negative electrode composite material, characterized in that: The steps include: Step 1: Add ethyl p-aminobenzoate and modified silicon oxide powder into a reaction kettle, stir at 50-60°C and 500-600r / min for 1-2h, add lithium sulfate and deionized water into the reaction kettle, continue stirring for 1-2h, filter, wash the filter cake with anhydrous ethanol 2-3 times, and vacuum dry to obtain composite silicon oxide powder; Step 2: Add composite silicon oxide powder, 2,5-diaminobenzoic acid and deionized water into a reactor, stir at 50-60°C and 500-700r / min for 40-45min, add tetrakis(4-formylphenyl)ethylene into the reactor, stir at 20-25°C and 500-600r / min for 10-12min, add dimethylacetamide, N,N-dimethylformamide and 4mol / L acetic acid solution into the reactor, continue to react for 1-2h, filter, wash the filter cake with deionized water 2-3 times, and vacuum dry to obtain a precursor powder; place the precursor powder in a muffle furnace, keep warm at 950-1000°C for 2-3h under nitrogen protection, and cool naturally to obtain a modified silicon oxide negative electrode substrate material; Step 3: uniformly mixing the modified silicon oxide negative electrode substrate material and the modified binder in a mass ratio of 8:1 to obtain a modified silicon oxide battery negative electrode composite material; The modified silicon dioxide powder is prepared by the following steps: The silicon dioxide powder is treated by electron beam irradiation to obtain ablated silicon dioxide powder with a rough surface and being porous; the ablated silicon dioxide powder and 5-7wt% sodium hydroxide solution are added into a reactor in a dosage ratio of 10-12g:500-600mL, stirred at 80-90°C and 500-600r / min for 40-60min, cooled naturally, filtered, and the filter cake is washed with deionized water until the last washing liquid is neutral, and vacuum dried to obtain modified silicon dioxide powder.

2. The method for preparing a modified silicon oxide battery negative electrode composite material according to claim 1, characterized in that: The ablated silicon oxide powder is prepared by the following steps: The silicon oxide powder with a particle size of 100-120 nm was placed in a stainless steel shell, and the shell was placed in the center of the mold. The silicon oxide powder was pressed into the shell using a pressure of 5-6 MPa on a tablet press, and the shell was placed on an electron beam workbench. The equipment was started and the vacuum system was turned on. When the vacuum degree of the vacuum chamber reached 6.5×10 -3 Pa, acceleration voltage 25-28KV, pulse duration 2-4μs, irradiation energy 2.2-2.5J / cm 2 When an electron beam is applied, the silicon oxide powder is directly irradiated to obtain ablated silicon oxide powder.

3. The method for preparing a modified silicon oxide battery negative electrode composite material according to claim 1, characterized in that: The dosage ratio of ethyl p-aminobenzoate, modified silicon oxide powder, lithium sulfate and deionized water in step 1 is 200-300 mL: 5-6 g: 3-4 g: 400-500 mL.

4. The method for preparing a modified silicon oxide battery negative electrode composite material according to claim 1, characterized in that: The dosage ratio of the composite silicon oxide powder, 2,5-diaminobenzoic acid, deionized water, tetrakis(4-formylphenyl)ethylene, dimethylacetamide, N,N-dimethylformamide, and acetic acid solution in step 2 is 4-5g:8-9g:400-500mL:8-9g:10-12mL:10-12mL:5-6mL.

5. The method for preparing a modified silicon oxide battery negative electrode composite material according to claim 1, characterized in that: The modified binder in step 3 is prepared by the following steps: The reducing product, 1 / 2 of the total amount of acrylic acid solution with a neutralization degree of 65-70% and deionized water are added to a reactor, stirred at 70-80°C and 500-600r / min for 40-60min, then stearic acid is added to the reactor, stirred at 50-60°C and 500-600r / min for 1-2h, cooled to 55-65°C, sodium sulfite, the remaining acrylic acid solution with a neutralization degree of 65-70% and hydroxymethyl acrylamide are added to the reactor, nitrogen is introduced for protection, heated to 70-80°C, stirred at 500-600r / min for 3-4h, filtered, the filter cake is washed with anhydrous ethanol for 2-3 times, and vacuum dried to obtain a modified binder.

6. The method for preparing a modified silicon oxide battery negative electrode composite material according to claim 5, characterized in that: The reduced product is prepared by the following steps: Add 1,3,6,8-tetrakis(4-formaldehydephenyl)-pyrene, sodium borohydride and deionized water into a reaction kettle in a dosage ratio of 7-9 g:30-40 g:300-400 mL, stir at 70-80° C. and 500-600 r / min for 40-60 min, filter, and wash the filter cake with tetrahydrofuran 2-3 times to obtain a reduced product.

7. The method for preparing a modified silicon oxide battery negative electrode composite material according to claim 5, characterized in that: The dosage ratio of the reducing material, acrylic acid solution, deionized water, stearic acid, sodium sulfite and hydroxymethyl acrylamide is 5-6g:80-90mL:200-300mL:20-30g:80-100mL:80-100mL.

8. A modified silicon oxide battery negative electrode composite material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the modified silicon oxide battery negative electrode composite material according to claim 8 in lithium ion battery negative electrode materials.

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