Silicon oxide-based composite anode material for lithium ion batteries and preparation method thereof

Abstract

The application discloses a high-performance silicon oxide-based composite negative electrode material for lithium ion batteries and a preparation method thereof. On the basis of a previous research result CN114937763A, a silicon-containing alloy material such as Fe-Si75 and TiSi2 alloy is further introduced to modify the silicon oxide negative electrode material, and a series of novel silicon oxide-based composite negative electrode materials are obtained. The novel silicon oxide-based composite negative electrode materials have good compatibility with high-pressure and conventional electrolytes and exhibit excellent electrochemical performance.

Description

Technical Field

[0001] This invention relates to a silicon oxide-based composite anode material for lithium-ion batteries and its preparation method. Background Technology

[0002] As a crucial energy source for electric vehicles, lithium-ion batteries face increasingly higher demands on battery technology amidst the transformation and development of the automotive industry. Safety and energy density are two key factors restricting the application of lithium-ion batteries in electric vehicles. The charging and discharging process of lithium-ion batteries involves multiple electrochemical reactions, directly affecting the structure, morphology, and performance of electrode materials. The specific capacity and discharge plateau of the electrode materials determine the battery's energy density. Developing high-voltage, high-capacity electrode materials is one of the key issues in achieving high-energy-density lithium-ion batteries.

[0003] The stability of the matching between electrode materials and electrolytes directly affects the electrochemical performance of lithium-ion batteries. Conventional electrolytes are unstable at high operating voltages, easily undergoing significant oxidative decomposition. The HF produced during electrolyte decomposition corrodes the positive electrode material, promoting the dissolution of transition metal ions and their migration to the negative electrode surface via the electrolyte, leading to increased battery impedance and decreased battery capacity. High-voltage electrolytes, however, can suppress electrolyte decomposition on the electrode surface and form a stable interfacial film by introducing additives.

[0004] The significant volume change during lithium insertion / extraction in silicon oxide anode materials leads to pulverization and shedding of the active material, as well as defects such as low initial coulombic efficiency and poor conductivity, failing to meet battery requirements. Our previous research, CN114937763A, disclosed a silicon oxide composite anode material and its preparation method. Micron-sized silicon oxide and commercially available artificial graphite were ball-milled, and the organic carbon source and oxide were uniformly mixed. The mixture was then spray-dried and subjected to high-temperature pyrolysis to obtain the silicon oxide composite anode material. The composite structure of this silicon oxide anode material features silicon oxide particles in full contact with the graphite matrix, coated with an amorphous carbon layer by introduced tin dioxide. The artificial graphite in the silicon oxide composite anode material has high conductivity and provides effective buffer space; the amorphous carbon layer, in addition to forming a conductive network and buffering expansion, prevents silicon oxide particle agglomeration and reduces direct contact between silicon oxide and the electrolyte; tin dioxide improves the overall conductivity of the material. This composite structure improves the initial charge / discharge efficiency, cycle stability, and rate performance of the silicon oxide anode material. This is attributed to the formation of a stable SEI film on the electrode and electrolyte surfaces, maintaining a stable material structure, and resulting in a smooth electrode surface without obvious cracks. However, the electrochemical performance of the composite anode material obtained through this technology still needs continuous improvement. Summary of the Invention

[0005] The object of the present invention is to provide a silicon oxide-based composite anode material for lithium-ion batteries and a preparation method thereof. Based on the previous research results of CN114937763A, silicon-containing alloy materials such as Fe-Si75 and TiSi2 alloys are further introduced to modify the silicon oxide anode material, and a series of novel silicon oxide-based composite anode materials obtained have good compatibility with high-voltage and conventional electrolytes and exhibit excellent electrochemical performance.

[0006] The present invention is achieved through the following technical solutions:

[0007] A preparation method of a silicon oxide-based composite anode material for lithium-ion batteries, the method comprising the following steps:

[0008] (1) Mix the crystallized silicon oxide, graphite and absolute ethanol uniformly and perform ball milling, and then add a silicon-containing alloy material to obtain a slurry;

[0009] (2) Add tin dioxide or titanium dioxide and an organic carbon source to water to obtain a mixed liquid, and then add the mixed liquid to the slurry obtained in step (1) and stir, add water to prepare a slurry with a solid-liquid mass-volume ratio of 1:10 - 1:20 g / mL, and perform spray drying to obtain a precursor of the silicon oxide-based composite anode material;

[0010] (3) Calcinate the precursor obtained in step (2) to obtain a silicon oxide-based composite anode material for lithium-ion batteries.

[0011] The silicon-containing alloy material described in step (1) is selected from Fe-Si75 or TiSi2 alloy.

[0012] The mass ratio of the crystallized silicon oxide, the silicon-containing alloy material, and graphite is 1:(0.1 - 1)(multiplied by)(5.3 - 18), preferably: 1:(0.67 - 1)(multiplied by)(12.8 - 18).

[0013] The crystallized silicon oxide (SiO x (0 < x < 2)) The specific steps of the crystallization treatment can be seen in CN114937763A.

[0014] In the ball milling treatment of step (1), the ball-to-material ratio is 20:1, and ball milling is performed at a rotation speed of 200 - 400 rpm for 1 - 8 h, and the slurry with a mesh size of 80 - 100 is screened out.

[0015] In step (1), the silicon-containing alloy can also be ball milled together with the silicon oxide, graphite and absolute ethanol to obtain a slurry.

[0016] The amount of tin dioxide or titanium dioxide added in step (2) is 0.5%-5% of the weight percentage of the crystallized silicon oxide and graphite mixture, and the amount of organic carbon source added is 3%-30% of the weight percentage of the crystallized silicon oxide and graphite mixture.

[0017] The organic carbon source mentioned in step (2) is styrene-butadiene rubber or glucose.

[0018] Preferably, the spray drying conditions in step (2) are: inlet air temperature 200℃-250℃, outlet air temperature 130℃-140℃, and feed rate 250-350mL / h.

[0019] Preferably, the calcination temperature in step (3) is 600℃-700℃ and the time is 3-6h.

[0020] The silicon oxide-based composite anode material provided by this invention has a composite structure in which silicon oxide, tin dioxide, and Fe-Si75 or TiSi2 form a composite phase and are attached between multiple layers of flake graphite. In this composite structure, the flake graphite can confine the easily expandable active material within it, effectively mitigating its volume expansion during charge and discharge. The carbon layer surrounding the particles also inhibits the volume expansion of the active material to a certain extent. Simultaneously, Fe-Si75 or TiSi2 and SnO2, with their smaller particle sizes, are attached to the crystallized silicon oxide and graphite surfaces, acting as a connector between different active materials, thereby increasing the overall conductivity of the composite material. Furthermore, the Fe-Si and Ti-Si phases in the Fe-Si75 or TiSi2 alloy are used as buffer layers to maintain the stability of the composite material structure. On the other hand, the cycle stability of the silicon oxide-based composite anode material modified by replacing tin dioxide with titanium dioxide is significantly improved. The silicon oxide-based composite anode material prepared by this method has advantages such as simple operation, easy control of conditions, good reproducibility, and stable electrochemical performance.

[0021] Therefore, this invention also protects the silicon oxide-based composite anode material prepared by the above preparation method.

[0022] This invention also protects a lithium-ion battery that uses the aforementioned silicon oxide composite anode material as the anode material.

[0023] The beneficial effects of this invention are as follows: Based on previous research results (CN114937763A), this invention further introduces silicon-containing alloy materials such as Fe-Si75 and TiSi2 alloys to modify silicon oxide anode materials, resulting in a series of novel silicon oxide-based composite anode materials. Furthermore, carbon-coated silicon oxide composite anode materials are obtained by replacing tin dioxide with titanium dioxide in the composite with silicon oxide / graphite. The above-mentioned silicon oxide-based composite anode materials exhibit good compatibility with high voltage and conventional electrolytes, demonstrating excellent electrochemical performance, primarily with a significant improvement in the initial charge-discharge efficiency and cycle stability of the composite material. Attached Figure Description

[0024] Figure 1 Here is a SEM image of the composite anode material obtained in Example 1;

[0025] Figure 2 Here is a SEM image of the composite anode material obtained in Example 9;

[0026] Figure 3 Here is a SEM image of the composite anode material obtained in Example 11;

[0027] Figure 4 Here is a SEM image of the composite anode material obtained in Example 17;

[0028] Figure 5 SEM image of the composite anode material obtained in Example 19;

[0029] Figure 6 Here is a SEM image of the negative electrode material obtained in Comparative Example 1;

[0030] Figure 7 Here is a SEM image of the composite anode material obtained in Comparative Example 2;

[0031] Figure 8 The cycling performance curves are for Examples 7-10 and Comparative Examples 1-2;

[0032] Figure 9 The cycling performance curves are for Examples 15-18 and Comparative Examples 1-2. Detailed Implementation

[0033] The following is a further description of the invention, but not a limitation thereof.

[0034] Example 1 (20% glucose as carbon source, 9% silicon suboxide, 1% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, high voltage electrolyte)

[0035] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 3.6g of SiO₂. x 0.4g Fe-Si75 and 36g artificial graphite were added to 60ml anhydrous ethanol and stirred until homogeneous. The mixture was then placed in a planetary ball mill with a ball-to-material ratio of 20:1 and milled at 200rpm for 1 hour. The resulting slurry was then sieved to an 80-mesh size. Tin dioxide and glucose were added to 50ml deionized water and magnetically stirred for 30 minutes. The amount of tin dioxide and glucose added was approximately equal to the amount of SiO2. x The mixture of Fe-Si75 alloy and artificial graphite was prepared at 1% and 20% by weight, respectively. Tin dioxide and glucose solution were added to the slurry to form a solid-liquid ratio of 1:20. The slurry was magnetically stirred for 1 hour and then spray-dried. The spray drying equipment was set with an inlet air temperature of 250℃, an outlet air temperature of 140℃, and a feed rate of 300 mL / h. The slurry passing through a 300-mesh sieve (SiO2) was then processed. x A precursor for a (1%Fe-Si / SnO2 / G)@C composite material was prepared. The precursor was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, held for 6 h, to obtain (SiO2 / G)@C composite material. x (1%Fe-Si / SnO2 / G)@C composite anode material. SEM image of the composite anode material is shown below. Figure 1 As shown, the electrochemical performance of the composite anode material was tested by assembling coin cells using a high-voltage electrolyte.

[0036] Example 2 (20% glucose as carbon source, 9% silicon suboxide, 1% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, conventional electrolyte)

[0037] The (SiO) obtained in Example 1 x The SEM image of the (1%Fe-Si / SnO2 / G)@C composite anode material is shown below. Figure 1 As shown, the electrochemical performance of the composite anode material was tested by assembling coin cells using conventional electrolytes.

[0038] Example 3 (20% glucose as carbon source, 8% silicon suboxide, 2% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, high voltage electrolyte)

[0039] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 3.2g of SiO₂. x0.8g Fe-Si75 and 36g artificial graphite were added to 60ml anhydrous ethanol and stirred until homogeneous. The mixture was then placed in a planetary ball mill with a ball-to-material ratio of 20:1 and milled at 200rpm for 1 hour. The resulting slurry was then sieved to an 80-mesh size. Tin dioxide and glucose were added to 50ml deionized water and magnetically stirred for 30 minutes. The amount of tin dioxide and glucose added was approximately equal to the amount of SiO2. x The mixture of Fe-Si75 alloy and artificial graphite was prepared at 1% and 20% by weight, respectively. Tin dioxide and glucose solution were added to the slurry to form a solid-liquid ratio of 1:20. The slurry was magnetically stirred for 1 hour and then spray-dried. The spray drying equipment was set with an inlet air temperature of 250℃, an outlet air temperature of 140℃, and a feed rate of 300 mL / h. The slurry passing through a 300-mesh sieve (SiO2) was then processed. x A precursor for a (2%Fe-Si / SnO2 / G)@C composite material was prepared. The precursor was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, held for 6 h, to obtain (SiO2 / G)@C composite material. x (2%Fe-Si / SnO2 / G)@C composite anode material. The electrochemical performance of the composite anode material was tested by assembling coin cells using a high-voltage electrolyte.

[0040] Example 4 (20% glucose as carbon source, 8% silicon suboxide, 2% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, conventional electrolyte)

[0041] The (SiO) obtained in Example 3 x The electrochemical performance of the composite anode material (2%Fe-Si / SnO2 / G)@C was tested by assembling coin cells with conventional electrolytes.

[0042] Example 5 (20% glucose as carbon source, 7% silicon suboxide, 3% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, high voltage electrolyte)

[0043] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 2.8g of SiO₂. x 1.2g Fe-Si75 and 36g artificial graphite were added to 60ml anhydrous ethanol and stirred until homogeneous. The mixture was then placed in a planetary ball mill with a ball-to-material ratio of 20:1 and milled at 200rpm for 1 hour. The resulting slurry was then sieved to an 80-mesh size. Tin dioxide and glucose were added to 50ml deionized water and magnetically stirred for 30 minutes. The amount of tin dioxide and glucose added was approximately equal to the amount of SiO2. xThe mixture of Fe-Si75 alloy and artificial graphite was prepared at 1% and 20% by weight, respectively. Tin dioxide and glucose solution were added to the slurry to form a solid-liquid ratio of 1:20. The slurry was magnetically stirred for 1 hour and then spray-dried. The spray drying equipment was set with an inlet air temperature of 250℃, an outlet air temperature of 140℃, and a feed rate of 300 mL / h. The slurry passing through a 300-mesh sieve (SiO2) was then processed. x The precursor of (3%Fe-Si / SnO2) / G@C composite material was prepared. The precursor was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, held for 6 h, to obtain (SiO2) / G@C composite material. x (3%Fe-Si / SnO2 / G)@C composite anode material. The electrochemical performance of the composite anode material was tested by assembling coin cells using a high-voltage electrolyte.

[0044] Example 6 (20% glucose as carbon source, 7% silicon suboxide, 3% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, conventional electrolyte)

[0045] The (SiO) obtained in Example 5 x The electrochemical performance of the (3%Fe-Si / SnO2 / G)@C composite anode material was tested by assembling coin cells with conventional electrolytes.

[0046] Example 7 (20% glucose as carbon source, 6% silicon suboxide, 4% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, high voltage electrolyte)

[0047] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 2.4g of SiO₂. x 1.6g Fe-Si75 and 36g artificial graphite were added to 60ml anhydrous ethanol and stirred until homogeneous. The mixture was then placed in a planetary ball mill with a ball-to-material ratio of 20:1 and milled at 200rpm for 1 hour. The resulting slurry was then sieved to an 80-mesh size. Tin dioxide and glucose were added to 50ml deionized water and magnetically stirred for 30 minutes. The amount of tin dioxide and glucose added was approximately equal to the amount of SiO2. x The mixture of Fe-Si75 alloy and artificial graphite was prepared at 1% and 20% by weight, respectively. Tin dioxide and glucose solution were added to the slurry to form a solid-liquid ratio of 1:20. The slurry was magnetically stirred for 1 hour and then spray-dried. The spray drying equipment was set with an inlet air temperature of 250℃, an outlet air temperature of 140℃, and a feed rate of 300 mL / h. The slurry passing through a 300-mesh sieve (SiO2) was then processed. xThe precursor of (4%Fe-Si / SnO2) / G@C composite material was prepared. The precursor was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, held for 6 h, to obtain (SiO2) / G@C composite material. x (4%Fe-Si / SnO2 / G)@C composite anode material. The electrochemical performance of the composite anode material was tested by assembling coin cells using a high-voltage electrolyte.

[0048] Example 8 (20% glucose as carbon source, 6% silicon suboxide, 4% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, conventional electrolyte)

[0049] The (SiO) obtained in Example 7 x The electrochemical performance of the composite anode material (4%Fe-Si / SnO2 / G)@C was tested by assembling coin cells with conventional electrolytes.

[0050] Example 9 (20% glucose as carbon source, 5% silicon suboxide, 5% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, high voltage electrolyte)

[0051] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 2.0g of SiO₂. x 2.0g Fe-Si75 and 36g artificial graphite were added to 60ml anhydrous ethanol and stirred until homogeneous. The mixture was then placed in a planetary ball mill with a ball-to-material ratio of 20:1 and milled at 200rpm for 1 hour. The resulting slurry was then sieved to an 80-mesh size. Tin dioxide and glucose were added to 50ml deionized water and magnetically stirred for 30 minutes. The amount of tin dioxide and glucose added was approximately equal to the amount of SiO2. x The mixture of Fe-Si75 alloy and artificial graphite was prepared at 1% and 20% by weight, respectively. Tin dioxide and glucose solution were added to the slurry to form a solid-liquid ratio of 1:20. The slurry was magnetically stirred for 1 hour and then spray-dried. The spray drying equipment was set with an inlet air temperature of 250℃, an outlet air temperature of 140℃, and a feed rate of 300 mL / h. The slurry passing through a 300-mesh sieve (SiO2) was then processed. x The precursor of (5%Fe-Si / SnO2) / G@C composite material was prepared. The precursor was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, held for 6 h, to obtain (SiO2) / G@C composite material. x (5%Fe-Si / SnO2 / G)@C composite anode material. SEM image of the composite anode material is shown below. Figure 2 As shown, the electrochemical performance of the composite anode material was tested by assembling coin cells using a high-voltage electrolyte.

[0052] Example 10 (20% glucose as carbon source, 5% silicon suboxide, 5% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, conventional electrolyte)

[0053] The (SiO) obtained in Example 9 x The SEM image of the (5%Fe-Si / SnO2 / G)@C composite anode material is shown below. Figure 2 As shown, the electrochemical performance of the composite anode material was tested by assembling coin cells using conventional electrolytes.

[0054] Example 11 (20% glucose as carbon source, 5% silicon suboxide, 5% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, graphite without ball milling and 1% tin dioxide added, high voltage electrolyte)

[0055] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 2.0g of SiO₂. x 2.0g Fe-Si75 was added to 60ml anhydrous ethanol and stirred until homogeneous. The mixture was then placed in a planetary ball mill with a ball-to-material ratio of 20:1 and milled at 200rpm for 1 hour. The resulting slurry was then sieved to an 80-mesh size. Tin dioxide, 36g artificial graphite, and glucose were added to 50ml deionized water and magnetically stirred for 30 minutes. The amounts of tin dioxide and glucose added were approximately equal to the amount of SiO2 added. x The weight percentages of Fe-Si75 alloy and artificial graphite mixture were 1% and 20%. Tin dioxide, artificial graphite, and glucose solution were added to the slurry to prepare a solid-liquid ratio of 1:20. The mixture was magnetically stirred for 1 hour and then spray-dried. The spray drying equipment was set with an inlet air temperature of 250℃, an outlet air temperature of 140℃, and a feed rate of 300 mL / h. The slurry passing through a 300-mesh sieve (SiO₂) was then processed. x The precursor of the (5%Fe-Si / SnO2-1) / G@C composite material was prepared. The precursor was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, held for 6 h, to obtain (SiO2-1) / G@C composite material. x (5%Fe-Si / SnO2 / G-1)@C composite anode material. SEM image of the composite anode material is shown below. Figure 3 As shown, the electrochemical performance of the composite anode material was tested by assembling coin cells using a high-voltage electrolyte.

[0056] Example 12 (20% glucose as carbon source, 5% silicon suboxide, 5% Fe-Si75 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, graphite without ball milling and 1% tin dioxide added, atmospheric pressure electrolyte)

[0057] The (SiO) obtained in Example 11 x The SEM image of the composite anode material (5%Fe-Si / SnO2 / G-1)@C is shown below. Figure 3 As shown, the electrochemical performance of the composite anode material was tested by assembling coin cells using conventional electrolytes.

[0058] Example 13 (20% glucose as carbon source, 15% silicon suboxide, 5% Fe-Si75 alloy and 80% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, high voltage electrolyte)

[0059] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 6.0g of SiO₂. x 2.0g Fe-Si75 and 32g artificial graphite were added to 60ml anhydrous ethanol and stirred until homogeneous. The mixture was then placed in a planetary ball mill with a ball-to-material ratio of 20:1 and milled at 200rpm for 1 hour. The resulting slurry was then sieved to an 80-mesh size. Tin dioxide and glucose were added to 50ml deionized water and magnetically stirred for 30 minutes. The amount of tin dioxide and glucose added was approximately equal to the amount of SiO2. x The mixture of Fe-Si75 alloy and artificial graphite was prepared at 1% and 20% by weight, respectively. Tin dioxide and glucose solution were added to the slurry to form a solid-liquid ratio of 1:20. The slurry was magnetically stirred for 1 hour and then spray-dried. The spray drying equipment was set with an inlet air temperature of 250℃, an outlet air temperature of 140℃, and a feed rate of 300 mL / h. The slurry passing through a 300-mesh sieve (SiO2) was then processed. x The precursor of (5%Fe-Si / SnO2-2) / G@C composite material was prepared. The precursor was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, held for 6 h, to obtain (SiO2-2) / G@C composite material. x (5%Fe-Si / SnO2 / G-2)@C composite anode material. The electrochemical performance of the composite anode material was tested by assembling coin cells using a high-voltage electrolyte.

[0060] Example 14 (20% glucose as carbon source, 15% silicon suboxide, 5% Fe-Si75 alloy and 80% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, conventional electrolyte)

[0061] The (SiO) obtained in Example 13x The electrochemical performance of the (5%Fe-Si / SnO2 / G-2)@C composite anode material was tested by assembling coin cells with conventional electrolytes.

[0062] Example 15 (20% glucose as carbon source, 6% silicon suboxide, 4% TiSi2 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, high voltage electrolyte)

[0063] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 2.4g of SiO₂. x 1.6g TiSi2 alloy and 36g artificial graphite were added to 60ml anhydrous ethanol and stirred until homogeneous. The mixture was then placed in a planetary ball mill with a ball-to-material ratio of 20:1 and milled at 200rpm for 1 hour. The resulting slurry was then sieved to an 80-mesh size. Tin dioxide and glucose were added to 50ml deionized water and magnetically stirred for 30 minutes. The amount of tin dioxide and glucose added was approximately equal to the amount of SiO2 alloy. x The mixture of TiSi2 alloy and artificial graphite was prepared at 1% and 20% by weight, respectively. Tin dioxide and glucose solution were added to the slurry to form a solid-liquid ratio of 1:20. The slurry was magnetically stirred for 1 hour and then spray-dried. The inlet air temperature of the spray dryer was set to 250℃, the outlet air temperature to 140℃, and the feed rate to 300mL / h. The SiO2 alloy was sieved through a 300-mesh sieve. x A precursor for a (4%TiSi2 / SnO2 / G)@C composite material was prepared. The precursor was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, held for 6 h, to obtain (SiO2 / G)@C composite material. x (4%TiSi2 / SnO2 / G)@C composite anode material. The electrochemical performance of the composite anode material was tested by assembling coin cells using a high-voltage electrolyte.

[0064] Example 16 (20% glucose as carbon source, 6% silicon suboxide, 4% TiSi2 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, conventional electrolyte)

[0065] The (SiO) obtained in Example 15 x The electrochemical performance of the composite anode material (4%TiSi2 / SnO2 / G)@C was tested by assembling coin cells with conventional electrolytes.

[0066] Example 17 (20% glucose as carbon source, 5% silicon suboxide, 5% TiSi2 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, high voltage electrolyte)

[0067] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 2g of SiO₂. x 2g TiSi2 alloy and 36g artificial graphite were added to 60ml anhydrous ethanol and stirred until homogeneous. The mixture was then placed in a planetary ball mill with a ball-to-material ratio of 20:1 and milled at 200rpm for 1 hour. The resulting slurry was then sieved to an 80-mesh size. Tin dioxide and glucose were added to 50ml deionized water and magnetically stirred for 30 minutes. The amount of tin dioxide and glucose added was approximately equal to the amount of SiO2 alloy. x The mixture of TiSi2 alloy and artificial graphite was prepared at 1% and 20% by weight, respectively. Tin dioxide and glucose solution were added to the slurry to form a solid-liquid ratio of 1:20. After magnetic stirring for 1 hour, spray drying was performed. The spray drying equipment was set with an inlet air temperature of 250℃, an outlet air temperature of 140℃, and a feed rate of 300 mL / h. The SiO2 alloy was sieved through a 300-mesh sieve. x The precursor of the (5%TiSi2 / SnO2) / G@C composite material was prepared. The precursor was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, held for 6 h, to obtain (SiO2 / 5%TiSi2 / SnO2) / G@C composite material. x (5%TiSi2 / SnO2 / G)@C composite anode material. SEM image of the composite anode material is shown below. Figure 4 As shown, the electrochemical performance of the composite anode material was tested by assembling coin cells using a high-voltage electrolyte.

[0068] Example 18 (20% glucose as carbon source, 5% silicon suboxide, 5% TiSi2 alloy and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, conventional electrolyte)

[0069] The (SiO) obtained in Example 17 x The SEM image of the (5%TiSi2 / SnO2 / G)@C composite anode material is shown below. Figure 4 As shown, the electrochemical performance of the composite anode material was tested by assembling coin cells using conventional electrolytes.

[0070] Example 19 (20% glucose as carbon source, 10% silica and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% titanium dioxide added, high voltage electrolyte)

[0071] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 4g of SiO₂. xAdd 36g of artificial graphite to 60ml of anhydrous ethanol, stir well, and place the mixture in a planetary ball mill with a ball-to-material ratio of 20:1. Mill at 200rpm for 1 hour, and sieve to obtain an 80-mesh slurry. Add titanium dioxide and glucose to 50ml of deionized water and stir magnetically for 30 minutes. The amount of titanium dioxide and glucose added is SiO2. x The mixture of titanium dioxide and glucose solution was added at 1% and 20% by weight, respectively, to form a slurry with a solid-liquid ratio of 1:20. After magnetic stirring for 1 hour, the slurry was spray-dried. The inlet air temperature of the spray dryer was set to 250℃, the outlet air temperature to 140℃, and the feed rate to 300mL / h. The slurry passing through a 300-mesh sieve (SiO₂) was then separated. x The precursor of the ( / TiO2 / G)@C composite material was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, and held for 6h to obtain (SiO2 / G)@C composite material. x / TiO2 / G)@C composite anode material. SEM image of the composite anode material is shown below. Figure 5 As shown, the electrochemical performance of the composite anode material was tested by assembling coin cells using a high-voltage electrolyte.

[0072] Example 20 (20% glucose as carbon source, 10% silica and 90% graphite mixed and ball-milled at 200 rpm for 1 h, 1% titanium dioxide added, conventional electrolyte)

[0073] The (SiO) obtained in Example 19 x / TiO2 / G)@C composite anode material, SEM image of the composite anode material is shown below. Figure 5 As shown, the electrochemical performance of the composite anode material was tested by assembling coin cells using conventional electrolytes.

[0074] Comparative Example 1 (Pristine SiO)

[0075] Micron-sized silicon suboxide with an average particle size of 3µm was selected, and SiO material passing through a 300-mesh sieve was obtained. The SEM image of the anode material is shown below. Figure 6 As shown, coin cells were assembled using conventional electrolytes to test their electrochemical performance.

[0076] Comparative Example 2 (20% glucose as carbon source, silica and graphite mixed and ball-milled at 200 rpm for 1 h, 1% tin dioxide added, solid-liquid ratio 1:20)

[0077] Micron-sized silicon suboxide with an average particle size of 3µm was placed in a heat treatment furnace under argon atmosphere and heated to 1050℃ for 3 hours to obtain crystallized SiO2. x Materials. Weigh out 4g of SiO₂. xAdd 36g of artificial graphite to 60mL of anhydrous ethanol, stir well, and place the mixture in a planetary ball mill with a ball-to-material ratio of 20:1. Mill at 200 rpm for 1 hour, and sieve to obtain an 80-mesh slurry. Add tin dioxide and glucose to 50mL of deionized water and stir magnetically for 30 minutes. The amounts of tin dioxide and glucose added are SiO₂, SiO₂, and glucose, respectively. x The weight percentages of the mixture of tin dioxide and glucose were 1% and 20% respectively. A mixture of tin dioxide and glucose was poured into the slurry, and deionized water was added to prepare a slurry with a solid-liquid ratio of 1:20. The mixture was magnetically stirred for 1 hour and then spray-dried. The inlet air temperature of the spray dryer was set to 250℃, the outlet air temperature to 140℃, and the feed rate to 300mL / h. The product passing through a 300-mesh sieve (SiO₂) was then separated. x The precursor of the (SnO2 / G)@C composite material was placed in an argon atmosphere tube furnace and heated to 600℃ at 5℃ / min, and held for 6h to obtain (SiO2 / G)@C composite material. x / SnO2 / G)@C composite anode material. SEM image of the composite anode material is shown below. Figure 7 As shown, the composite material was assembled into coin cells using a conventional electrolyte, and its electrochemical performance was tested.

[0078] The positive electrode materials prepared in Examples 1-20 and Comparative Examples 1-2 were used to fabricate 2032 coin cell simulated batteries to test their electrochemical performance. Active material, acetylene black, SBR, and CMC were weighed in a mass ratio of 8:1:0.5:0.5. SBR and CMC were first dissolved in deionized water, and then the uniformly mixed active material and acetylene black powder were added to form a slurry, which was then uniformly coated onto a copper foil substrate. The wet electrode was placed in a vacuum drying oven and dried at 80°C for 12 hours. The simulated battery was assembled in a dry vacuum glove box. The self-made electrode was used as the positive electrode, a lithium metal sheet as the negative electrode, a Celgard 2500 membrane as the separator, and both high-voltage and conventional electrolytes were used.

[0079] Table 1 Electrochemical performance of the negative electrode materials in the examples and comparative examples

[0080]

[0081] As shown in Table 1, with the same electrolyte, the initial charge-discharge efficiency and reversible capacity of the composite material continuously increase with the increase of the silicon-iron alloy content in the silicon oxide-based composite anode material. Choosing a high-voltage electrolyte helps improve the initial charge-discharge efficiency of the composite material. All modified silicon oxide-based composite anode materials exhibit better initial charge-discharge efficiency and cycle stability than Comparative Example 1. Batteries assembled with a mass ratio of crystallized silicon oxide, silicon-containing alloy material, and graphite of 1:1:18 using a silicon-iron alloy and high voltage and conventional electrolyte, such as Examples 9-12, all show better initial charge-discharge efficiency than Comparative Example 2; except for Examples 11 and 13, the capacity retention of the silicon oxide-based composite anode materials obtained in the other examples after 300 cycles is better than that of Comparative Example 2. In particular, the composite anode material obtained by introducing titanium dioxide to replace tin dioxide exhibits excellent cycle performance. Composite materials of silicon suboxide, after crystallization treatment, combined with graphite, tin dioxide, Si-Fe75, or TiSi2 alloys using ball milling and spray drying methods, and modified with carbon coating, exhibit good electrochemical performance. After ball milling, the silica and graphite particles are refined, with some graphite particles appearing as flakes. After spray drying, spherical particles appear. Figures 1-5 The Si in Si-Fe75 or TiSi2 alloys enhances the reversible capacity of the composite material and reduces side reactions between the electrode active material and the electrolyte, thus improving the initial charge-discharge efficiency. The thin, flake-like graphite, after ball milling, forms a skeletal structure, and the alloy's buffer phase maintains the stability of the material structure, effectively mitigating the volume effect during the lithium insertion / extraction process of silicon oxide anode materials, thereby achieving excellent cycle performance, such as... Figure 8 and 9 As shown.

Claims

1. A method for preparing a silicon oxide-based composite anode material for lithium ion batteries, characterized in that, The method comprises the following steps: (1) mixing the crystallized silicon oxide, graphite and anhydrous ethanol uniformly, and then adding a silicon-containing alloy material to obtain a slurry; the silicon-containing alloy material is selected from Fe-Si75 or TiSi2 alloy; the mass ratio of the crystallized silicon oxide, the silicon-containing alloy material and the graphite is 1:(0.1-1):(5.3-18); (2) adding tin dioxide or titanium dioxide and an organic carbon source into water to obtain a mixed liquid, and then adding the mixed liquid into the slurry obtained in step (1) to stir, adding water to prepare a slurry with a solid-liquid mass volume ratio of 1:10-1:20 g / mL, and spray drying to obtain a precursor of a silicon oxide-based composite negative electrode material; (3) calcining the precursor obtained in step (2) to obtain a silicon oxide-based composite negative electrode material for lithium ion batteries.

2. The production method according to claim 1, characterized by, The mass ratio of the crystallized silicon oxide, the silicon-containing alloy material and the graphite is 1:(0.67-1):(12.8-18).

3. The production method according to claim 1, characterized by, In the ball milling treatment of step (1), the ball-to-material ratio is 20:1, and the ball milling is performed at a speed of 200-400 rpm for 1-8 h, and the slurry with a particle size of 80-100 mesh is screened out.

4. The method of claim 1, wherein, In step (1), the silicon-containing alloy is co-milled with the silicon oxide, graphite and anhydrous ethanol to obtain the slurry.

5. The preparation method according to claim 1, characterized in that, In step (2), the addition amount of the tin dioxide or titanium dioxide is 0.5%-5% of the weight percentage of the mixture of the crystallized silicon oxide and the graphite, and the addition amount of the organic carbon source is 3%-30% of the weight percentage of the mixture of the crystallized silicon oxide and the graphite; the organic carbon source in step (2) is butyl rubber or glucose.

6. The method of claim 1, wherein, In step (2), the spray drying conditions are as follows: the inlet air temperature is 200-250°C, the outlet air temperature is 130-140°C, and the feeding rate is 250-350 mL / h.

7. The preparation method according to claim 1, characterized in that, In step (3), the calcination temperature is 600-700°C, and the time is 3-6 h.

8. A lithium ion battery, wherein the silicon oxide-based composite negative electrode material prepared by the preparation method of claim 1 is used as a negative electrode material.

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