Composite modified silicon-based negative electrode material and preparation method and application thereof

Abstract

The application discloses a kind of composite modified silicon-based negative electrode materials and preparation method, application, belong to negative electrode material technical field.The preparation method includes the following steps: (1) after mixing nano silicon particles and arsenic powder, obtain mixed material, mixed material is placed in reaction equipment, vacuum is extracted after, inert gas is introduced to pressurize, and under the condition of pressurization, heating arsenic reaction is carried out, obtain Si@SiAs2;Wherein: the molar ratio of nano silicon and arsenic powder is (5~7.5):(2~3);(2) after solid-phase mixing Si@SiAs2 With carbon material, obtain composite modified silicon-based negative electrode material.The application is synthesized by arsenization method Si@SiAs2@C Composite modified silicon-based negative electrode material;After arsenization treatment, the composite modified silicon-based negative electrode material shows higher conductivity, and the assembled energy storage battery has good cycle stability.

Description

Technical Field

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

[0002] Currently, the development direction of anode materials for rechargeable batteries mainly focuses on improving their capacity. Existing silicon-based anode material technology is relatively mature, with capacities exceeding 1000 mAh / g, far surpassing graphite-based materials. Moreover, silicon-based anode materials have gained widespread attention and research due to their abundant resources and low cost. However, the significant volume changes during lithium-ion intercalation / deintercalation in silicon-based anode materials lead to the fragmentation and breakage of the silicon active material, reducing the battery's cycle performance and lifespan. Therefore, further improving the performance of silicon-based anode materials is crucial for enhancing the overall performance of batteries. Summary of the Invention

[0003] Therefore, the purpose of this invention is to provide a composite modified silicon-based anode material, its preparation method, and its application.

[0004] In a first aspect, the present invention provides a method for preparing a composite modified silicon-based anode material, comprising the following steps:

[0005] (1) After mixing nano-silicon particles with arsenic powder, a mixture is obtained. The mixture is placed in a reaction device, vacuumed, and then pressurized by introducing inert gas. Under pressurized conditions, a heating arsenination reaction is carried out to obtain Si@SiAs2. The molar ratio of nano-silicon to arsenic powder is (5~7.5):(2~3).

[0006] (2) After solid-phase mixing of Si@SiAs2 with carbon materials, a composite modified silicon-based anode material is obtained, with the chemical formula: Si@SiAs2@C.

[0007] Preferably, in step (1), the particle size of silicon particles is 50~100nm and the particle size of arsenic powder is 200~500nm.

[0008] Preferably, in step (1), the inert gas is argon; the pressure inside the reaction equipment is controlled to be 0.4~0.6 MPa by continuously introducing inert gas.

[0009] Preferably, in step (1), the heating temperature is 800~1000℃ and the arsenination reaction time is 10~50h.

[0010] Preferably, in step (2), the carbon material is one or more of natural graphite, commercial graphite, and domestically produced mesophase carbon microspheres (MCMB); the mass ratio of Si@SiAs2 to carbon material is (30~40):(10~15).

[0011] Preferably, in step (2), the solid phase composite is ball milling solid phase composite, and the solid phase composite time is 1~6h.

[0012] Secondly, the present invention provides a composite modified silicon-based anode material, which is prepared by the aforementioned preparation method.

[0013] Thirdly, the present invention provides an energy storage battery comprising the aforementioned composite modified silicon-based anode material.

[0014] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects:

[0015] (1) The present invention synthesizes Si@SiAs2@C composite modified silicon-based anode material by arsenide method; after arsenide treatment, the composite modified silicon-based anode material exhibits high conductivity, and its assembled energy storage battery has good cycle stability.

[0016] (2) The modification method of the present invention is simple and the modification effect is good, which provides ideas for the further practical application of silicon anode. Attached Figure Description

[0017] Figure 1 The image shows the XRD pattern of SiAs2 prepared in Comparative Example 2.

[0018] Figure 2 The graphs show the electrochemical cycling curves of batteries assembled with the negative electrode materials prepared in Examples 1-5 and Preparation Examples 1-2. Detailed Implementation

[0019] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0020] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0021] As mentioned above, in a first aspect, the present invention provides a method for preparing a composite modified silicon-based anode material, comprising the following steps:

[0022] (1) After mixing nano-silicon particles with arsenic powder, a mixture is obtained. The mixture is placed in a reaction device, vacuumed, and then pressurized by introducing inert gas. Under pressurized conditions, a heating arsenination reaction is carried out to obtain Si@SiAs2. The molar ratio of nano-silicon to arsenic powder is (5~7.5):(2~3), including but not limited to 5:2, 5:2.5, 5:3, 6:2, 6:2.5, 7.5:2, 7.5:3, etc.

[0023] (2) After solid-phase mixing of Si@SiAs2 with carbon materials, a composite modified silicon-based anode material is obtained, with the chemical formula: Si@SiAs2@C.

[0024] In this invention, by controlling the ratio of nano-silicon to arsenic powder and conducting a heated arsenination reaction under pressure, a Si@SiAs2 particle structure with nano-silicon as the core and silicon arsenide (SiAs2) as the shell is generated. The SiAs2 shell structure can reduce the volume expansion of the nano-silicon particles, improve their structural stability and conductivity, and thus improve the electrochemical performance of silicon-based anode materials. In addition, the carbon composite layer can further improve the conductivity and structural stability of the silicon-based material, and can form a synergistic effect with the SiAs2 shell, thus significantly improving the performance of the composite-modified silicon-based anode material.

[0025] Preferably, in step (1), the particle size of the silicon particles is 50~100nm, including but not limited to 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc.; the particle size of the arsenic powder is 200~500nm, including but not limited to 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc.

[0026] Preferably, in step (1), the inert gas is argon; the pressure inside the reaction equipment is controlled to be 0.4~0.6 MPa by continuously introducing inert gas, including but not limited to 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.55 MPa, 0.6 MPa, etc.

[0027] Preferably, in step (1), the heating temperature is 800~1000℃, including but not limited to 800℃, 850℃, 900℃, 950℃, 1000℃, etc.; the arsenination reaction time is 10~50h, including but not limited to 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 50h, etc.

[0028] In this invention, by controlling the reaction conditions of the arsenination reaction, the uniformity of the arsenination reaction can be improved, the uniformity of the SiAs2 shell can be improved, and thus the overall performance of Si@SiAs2 can be better enhanced.

[0029] Preferably, in step (2), the carbon material is one or more of natural graphite, commercial graphite, and domestically produced mesophase carbon microspheres (MCMB); the mass ratio of Si@SiAs2 to carbon material is (30~40):(10~15).

[0030] Preferably, in step (2), the solid phase composite is ball milling solid phase composite; the solid phase composite time is 1~6h, including but not limited to 1h, 2h, 3h, 4h, 5h, 6h, etc.

[0031] Secondly, the present invention provides a composite modified silicon-based anode material, which is prepared by the aforementioned preparation method.

[0032] Thirdly, the present invention provides an energy storage battery comprising the aforementioned composite modified silicon-based anode material.

[0033] Example 1

[0034] 15g of nano-silicon (80nm) and 20g of arsenic powder (300nm) were mechanically mixed to obtain a mixture. The mixture was placed in a reaction device, and after evacuation, argon gas was continuously introduced to control the pressure inside the reaction device to 0.5MPa. Under this pressure, the mixture was heated to 900℃ and subjected to an arsenination reaction for 40h to obtain Si@SiAs2 material.

[0035] By ball milling 34g of Si@SiAs2 material with 10g of commercial graphite for 3h, Si@SiAs2@C composite modified anode material can be obtained.

[0036] Comparative Example 1

[0037] Si@C modified anode material can be prepared by ball milling 34g of nano-silicon and 10g of commercial graphite for 3h to form a solid-state composite.

[0038] Comparative Example 2

[0039] 5.6g of nano-silicon (80nm) and 30g of arsenic powder (300nm) were mechanically mixed to obtain a mixture. The mixture was placed in a reaction device, and after evacuation, argon gas was continuously introduced to control the pressure inside the reaction device to 0.5MPa. Under this pressure, the mixture was heated to 900℃ and subjected to an arsenination reaction for 40h to obtain SiAs2 material.

[0040] 23.7 g of SiAs2 material was ball-milled with 11.3 g of nano-silicon for 3 h to obtain Si@SiAs2 material. Then, 34 g of Si@SiAs2 material was ball-milled with 10 g of commercial graphite for 3 h to obtain Si@SiAs2@C composite modified anode material.

[0041] The XRD pattern of the SiAs2 material prepared in this comparative example is shown in the figure. Figure 1 Its characteristic peaks correspond perfectly to those of the standard SiAs2 card.

[0042] Example 2

[0043] The process is basically the same as in Example 1, except that 20g of nano-silicon and 15g of arsenic powder are mixed to obtain a mixture.

[0044] Example 3

[0045] The process is basically the same as in Example 1, except that 15g of nano-silicon and 20g of arsenic powder are mixed to obtain a mixture.

[0046] Example 4

[0047] 15g of nano-silicon (50nm) and 20g of arsenic powder (500nm) were mechanically mixed to obtain a mixture. The mixture was placed in a reaction device, and after evacuation, argon gas was continuously introduced to control the pressure inside the reaction device to 0.6MPa. Under this pressure, the mixture was heated to 800℃ and subjected to an arsenination reaction for 50h to obtain Si@SiAs2 material.

[0048] By ball milling 30g of Si@SiAs2 material with 15g of natural graphite for 1 hour, Si@SiAs2@C composite modified anode material can be obtained.

[0049] Example 5

[0050] 20g of nano-silicon (100nm) and 15g of arsenic powder (300nm) were mechanically mixed to obtain a mixture. The mixture was placed in a reaction device, and after evacuation, argon gas was continuously introduced to control the pressure inside the reaction device to 0.4MPa. Under this pressure, the mixture was heated to 1000℃ and subjected to an arsenination reaction for 10h to obtain Si@SiAs2 material.

[0051] By ball milling 40g of Si@SiAs2 material with 10g of domestically produced mesophase carbon microspheres for 6h, Si@SiAs2@C composite modified anode material can be obtained.

[0052] Using the negative electrode material powders obtained in Examples 1-5 and Comparative Examples 1-2 as active materials, they were mixed with conductive agent acetylene black (AB) and binder polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1, respectively. N-methylpyrrolidone (NMP) was used as the solvent, and the mixture was stirred at 800 r / min for 2 hours in a small beaker to obtain a slurry. The slurry was coated onto current collector aluminum foil using an automatic coating machine, laid flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. After die-cutting to prepare electrode sheets with a diameter of 14 mm, the sheets were dried in a vacuum drying oven at 105°C for 4 hours. The electrode sheets were then placed in a glove box filled with argon atmosphere (both moisture and oxygen content below 0.1 ppm) for 4 hours to reduce the moisture adsorbed during transfer. Finally, they were assembled into CR2032 coin cells in the glove box. The battery uses a 18mm diameter porous polyethylene membrane, model Celgard2300, as the separator, and a lithium sheet as the counter electrode.

[0053] After the battery assembly was completed and aged for 12 hours, a 2C rate charge-discharge test was conducted within a voltage range of 0.1-3.0V, with 50 cycles. The results are shown below. Figure 2 See Table 1.

[0054] Table 1

[0055]

[0056] from Figure 2 As can be seen from the data in Table 1, in Comparative Example 1, the nano-silicon was coated only with graphite, resulting in a battery with poor specific capacity and cycle stability. In Comparative Example 2, the nano-silicon was first solid-phase coated with SiAs2, and then coated with carbon. The specific capacity and cycle stability of the battery assembled with the prepared negative electrode material were slightly improved compared to Comparative Example 1, but the improvement was not significant, indicating that the composite solid-phase coating of SiAs2 has limited effect on improving the performance of nano-silicon. The battery assembled with the negative electrode material prepared in Example 1 showed a significant improvement in specific capacity and cycle temperature stability compared to Comparative Examples 1 and 2, indicating that in-situ coating of SiAs2 on silicon particles through arsenide reaction can significantly improve the electrochemical performance of silicon-based negative electrode materials. In the preparation methods of Examples 2 and 3, the amount of arsenic powder added was either less or more, and the specific capacity and cycle stability of the batteries assembled with the corresponding negative electrode materials were somewhat lower than those of Example 1, indicating that in-situ coating of SiAs2 has a better ratio. In Examples 4 and 5, the process parameters were adjusted, and the specific capacity and cycle stability of the batteries assembled with the corresponding negative electrode materials fluctuated to some extent, but both exhibited superior electrochemical performance.

[0057] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a composite modified silicon-based anode material, characterized in that, Includes the following steps: (1) After mixing nano-silicon particles with arsenic powder, a mixture is obtained. The mixture is placed in a reaction device, vacuumed, and then pressurized by introducing inert gas. Under pressurized conditions, a heating arsenination reaction is carried out to obtain Si@SiAs2. The molar ratio of nano-silicon to arsenic powder is (5~7.5):(2~3). (2) After solid-state composite of Si@SiAs2 with carbon materials, a composite modified silicon-based anode material is obtained; In step (1), the inert gas is argon; the pressure inside the reaction equipment is controlled to be 0.4~0.6 MPa by continuously introducing inert gas. In step (1), the heating temperature is 800~1000℃ and the arsenination reaction time is 10~50h.

2. The method for preparing the composite modified silicon-based anode material according to claim 1, characterized in that, In step (1), the particle size of silicon particles is 50~100nm, and the particle size of arsenic powder is 200~500nm.

3. The method for preparing the composite modified silicon-based anode material according to claim 1, characterized in that, In step (2), the mass ratio of Si@SiAs2 to carbon material is (30~40):(10~15).

4. The method for preparing the composite modified silicon-based anode material according to claim 1, characterized in that, In step (2), the solid phase composite is ball milling solid phase composite, and the solid phase composite time is 1~6h.

5. A composite modified silicon-based anode material, characterized in that, It is prepared by any of the preparation methods described in claims 1 to 4.

6. The application of a composite modified silicon-based anode material according to claim 5 in an energy storage battery.

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