A sodium-ion battery electrode containing composite nano-silicon carbide and its preparation method

Abstract

This invention discloses a sodium-ion battery electrode containing composite nano-silicon carbide and its preparation method, relating to the field of sodium-ion battery electrodes. The sodium-ion battery electrode containing composite nano-silicon carbide comprises 0.5 wt% to 5 wt% of nano-silicon carbide particles and 0.5 wt% to 5 wt% of silicon carbide whiskers, by weight percentage; the weight ratio of the nano-silicon carbide particles to the silicon carbide whiskers is 1 to 2:1. This invention enhances the thermal conductivity of the sodium-ion battery electrode by adding silicon carbide, thereby preventing the sodium-ion battery from aging at high temperatures.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery electrodes, specifically a sodium-ion battery electrode containing composite nano-silicon carbide and its preparation method. Background Technology

[0002] Sodium-ion batteries, as a potential alternative to lithium-ion batteries, have attracted considerable attention due to their abundant resources and low cost. However, sodium-ion batteries still face challenges in terms of energy density, cycle stability, and thermal management. Sodium-ion batteries generate a significant amount of heat during charging and discharging. If this heat cannot dissipate in time, the battery temperature will rise rapidly. High temperatures can cause many problems for sodium-ion batteries, such as accelerating the aging of internal chemical substances and shortening battery life; significantly reducing the effective capacity of the battery under high temperatures, leading to reduced usage time of devices even when fully charged; and because the electrolyte and electrode chemistry are more unstable at high temperatures, the high-temperature environment can cause the generation of gases inside the battery, leading to battery expansion, and even explosion or combustion. Therefore, how to avoid battery overheating and improve battery performance has become an urgent problem to be solved in this field. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies that generate a large amount of heat during charging and discharging, and that sodium-ion electrodes age rapidly at high temperatures. This invention provides a sodium-ion battery electrode containing composite nano-silicon carbide and its preparation method. By adding silicon carbide, thermal conductivity is enhanced, thereby improving the thermal conductivity of the sodium-ion battery electrode and preventing sodium-ion batteries from aging at high temperatures.

[0004] The objective of this invention is mainly achieved through the following technical solutions:

[0005] A sodium-ion battery electrode containing composite nano-silicon carbide comprises the following components in the following proportions:

[0006] 0.5Wt%~5Wt% nano-silicon carbide particles;

[0007] 0.5Wt%~5Wt% silicon carbide whiskers;

[0008] The weight ratio of the nano-silicon carbide particles to the silicon carbide whiskers is 1~2:1.

[0009] Currently, research and development typically focuses on the activity of current collector materials to achieve lower resistivity, or on the material structure to allow the battery electrodes to carry more active materials. This can effectively improve battery performance and achieve breakthroughs in battery energy density. However, this approach compromises the stability of sodium-ion batteries, preventing them from effectively dissipating heat during charging and discharging. This leads to high temperatures in sodium-ion batteries, which in turn cause rapid aging and affect their lifespan.

[0010] The weight ratio of the nano-silicon carbide particles to the silicon carbide whiskers is 1 to 2:1, which can better form a point-line composite thermal conductive network, thereby enhancing the thermal conductivity of the battery electrode of the present invention.

[0011] This invention considers adding a thermally conductive agent to the battery electrode to enhance its thermal conductivity, thereby improving the heat dissipation efficiency of sodium-ion batteries. There are many forms and types of thermally conductive agents. Materials with excellent thermal conductivity, in descending order, are diamond (2300 W / m·K), diamond (>1000 W / m·K), silicon carbide (490 W / m·K), silver (429 W / m·K), pure copper (401 W / m·K), gold (317 W / m·K), pure aluminum (237 W / m·K), and brass (70~183 W / m·K). Diamond has excellent thermal conductivity but poor electrical insulation; silver, copper, and gold are relatively expensive. Therefore, silicon carbide is an ideal thermally conductive material. Besides material properties, the microstructure and distribution of the thermally conductive agent are important factors affecting its thermal conductivity. Particulate thermally conductive materials have a zero-dimensional structure, while fibrous thermally conductive materials have a one-dimensional structure. Fine-particle, zero-dimensional thermal conductive agents provide point contact, while linear, one-dimensional thermal conductive agents provide line contact. Particulate thermal conductive agents are more easily and uniformly dispersed on the surface of active material particles, forming a good short-range thermal pathway. However, they are not conducive to forming long-range thermal pathways along the thickness of the entire electrode. This invention incorporates two different forms of silicon carbide thermal conductive agents into the battery electrode using a material composition of 0.5–5 wt% nano-silicon carbide particles and 0.5–5 wt% silicon carbide whiskers. Utilizing the advantages of each different form of silicon carbide thermal conductive agent, the mixed structure of the two structures facilitates the formation of a complete thermal conductive network. By adding nano-silicon carbide particles and silicon carbide whiskers, the sodium-ion battery electrode of this invention significantly improves thermal conductivity, helps improve battery thermal management, reduces battery temperature rise, and enhances battery cycle stability and safety. Simultaneously, the optimized component ratio and preparation process ensure that the electrode exhibits excellent electrochemical performance, providing strong technical support for the application of sodium-ion batteries.

[0012] Furthermore, the particle size of the nano-silicon carbide particles is 50 nm to 500 nm, the diameter of the silicon carbide whiskers is 0.2 μm to 0.5 μm, and the length of the silicon carbide whiskers is 2 μm to 10 μm.

[0013] The particle size of the nano-silicon carbide particles is 50 nm to 500 nm, which can ensure uniform coating of active materials and prevent particles that are too small to disperse.

[0014] The diameter of the silicon carbide whiskers is 0.2 μm to 0.5 μm, and the length of the silicon carbide whiskers is 2 μm to 10 μm. This can match the particle size of the active material particles, ensuring uniform connection of different active material particles while preventing the risk of coating difficulties due to excessively long particle sizes.

[0015] Furthermore, it also includes the following proportions of ingredients:

[0016] 0.5wt%~5wt% conductive agent;

[0017] 1wt%~5wt% adhesive;

[0018] 97.5wt%~80wt% active substances.

[0019] The active material in this invention is a sodium-ion battery active material, such as layered oxides or polyanionic materials, but lithium-ion battery active materials can also be used. Specifically, the active material can be a Na2Ti6O13 crystalline phase active material, a melt-solidified body represented by NaxMyP2O7, Na4Ni3(PO4)2(P2O7) crystals, NaNiPO4 crystals, silicon inclusion compound electrode active materials, etc.

[0020] A method for preparing a sodium-ion battery electrode containing composite nano-silicon carbide includes the following steps:

[0021] S1: Add 1-5 parts by weight of adhesive to 100 parts by weight of solvent, stir evenly to obtain adhesive solution;

[0022] S2: Add 0.5~5.5 parts by weight of nano-silicon carbide particles and 0.5~5.5 parts by weight of silicon carbide whiskers to the adhesive solution, wherein the nano-silicon carbide particles and silicon carbide whiskers are added to the adhesive solution in a weight ratio of 1~2:1 and dispersed evenly to form a thermally conductive adhesive solution;

[0023] S3: Add 0.5-6 parts by weight of conductive agent to 100 parts of thermally conductive adhesive and disperse evenly to form a conductive and thermally conductive slurry;

[0024] S4: Add 60-200 parts by weight of active material to 100 parts of conductive and thermally conductive slurry, and disperse and homogenize to obtain electrode slurry;

[0025] Electrode slurry is coated onto the surface of the current collector with a coating thickness of 100 μm to 300 μm to obtain a battery electrode containing composite nano-silicon carbide.

[0026] Furthermore, the particle size of the active substance is 5~10 μm.

[0027] The active material in this invention has a particle size of 5~10 μm, thereby ensuring sufficient material stability and superior electrical properties.

[0028] Furthermore, the coating thickness of the battery electrode containing composite nano-silicon carbide is 100~300um.

[0029] The coating thickness is guaranteed to be within the range of 100 μm to 300 μm, which ensures that the electrode has good electrical performance.

[0030] Furthermore, the electrode slurry has a solid content of 40 wt% to 65 wt% and a viscosity of 3000 mPa·s to 5000 mPa·s.

[0031] In summary, the present invention has the following advantages compared with the prior art:

[0032] This invention, by incorporating nano-silicon carbide particles and silicon carbide whiskers, significantly improves the thermal conductivity of the sodium-ion battery electrode, thus aiding in improved battery thermal management, reducing battery temperature rise, and enhancing battery cycle stability and safety. Simultaneously, the optimized component ratios and preparation process ensure the electrode exhibits excellent electrochemical performance, providing strong technical support for the application of sodium-ion batteries. Attached Figure Description

[0033] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0034] Figure 1 SEM image of the sodium-ion battery electrode prepared in Example 1 of this invention;

[0035] Figure 2 This is a schematic diagram of the thermal conductive network structure of the sodium-ion battery electrode prepared in Example 1 of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0037] Example 1:

[0038] S1: Add 2.0g of adhesive to 100g of solvent and stir until completely dissolved to obtain adhesive solution;

[0039] S2: Add 2.0g of nano silicon carbide particles and 1.0g of silicon carbide whiskers to 102g of adhesive solution in proportion, stir and disperse at high speed for 30 minutes to form a thermally conductive adhesive solution.

[0040] S3: Add 2.0g of conductive agent to 105g of thermally conductive adhesive and continue to disperse for 30 minutes to form a conductive and thermally conductive slurry;

[0041] S4: Add 93g of active material to 10g of conductive and thermally conductive slurry, stir and disperse at high speed for 60 minutes, and adjust the viscosity to 3000~5000mPa·s to obtain the electrode slurry. Coat the electrode slurry onto the surface of the current collector, control the coating thickness to 150um, and after drying and rolling, obtain the battery electrode containing composite nano-silicon carbide.

[0042] Example 2:

[0043] S1: Add 2.0g of adhesive to 100g of solvent and stir until completely dissolved to obtain adhesive solution;

[0044] S2: Add 1.0g of nano silicon carbide particles and 0.5g of silicon carbide whiskers to 102g of adhesive solution in proportion, stir and disperse at high speed for 30 minutes to form a thermally conductive adhesive solution.

[0045] S3: Add 2.0g of conductive agent to 103.5g of thermally conductive adhesive and continue to disperse for 30 minutes to form a conductive and thermally conductive slurry;

[0046] S4: Add 94.5g of active material to 105.5g of conductive and thermally conductive slurry, stir and disperse for 60 minutes, and adjust the viscosity to 3000~5000mPa·s to obtain the electrode slurry. Coat the electrode slurry onto the surface of the current collector, control the coating thickness to 150um, and after drying and rolling, obtain the battery electrode containing composite nano-silicon carbide.

[0047] Example 3:

[0048] S1: Add 2.0g of adhesive to 100g of solvent and stir until completely dissolved to obtain adhesive solution;

[0049] S2: Add 1.0g of nano-silicon carbide particles and 1.0g of silicon carbide whiskers to 102g of adhesive solution in proportion, stir and disperse at high speed for 30 minutes to form a thermally conductive adhesive solution.

[0050] S3: Add 2.0g of conductive agent to 104g of thermally conductive adhesive and continue to disperse for 30 minutes to form a conductive and thermally conductive slurry;

[0051] S4: Add 94.0g of active material to 106g of conductive and thermally conductive slurry, stir and disperse for 60 minutes, and adjust the viscosity to 3000~5000mPa·s to obtain the electrode slurry. Coat the electrode slurry onto the surface of the current collector, control the coating thickness to 150um, and after drying and rolling, obtain the battery electrode containing composite nano-silicon carbide.

[0052] Example 4:

[0053] S1: Add 2.0g of adhesive to 100g of solvent and stir until completely dissolved to obtain adhesive solution;

[0054] S2: Add 0.5g of nano-silicon carbide particles and 0.5g of silicon carbide whiskers to 102g of adhesive solution in a certain proportion, and stir and disperse at high speed for 30 minutes to form a thermally conductive adhesive solution.

[0055] S3: Add 2.0g of conductive agent to 103g of thermally conductive adhesive and continue to disperse for 30 minutes to form a conductive and thermally conductive slurry;

[0056] S4: Add 95.0g of active material to 105g of conductive and thermally conductive slurry, stir and disperse for 60 minutes, and adjust the viscosity to 3000~5000mPa·s to obtain the electrode slurry. Coat the electrode slurry onto the surface of the current collector, control the coating thickness to 150um, and obtain a battery electrode containing composite nano-silicon carbide after drying and rolling.

[0057] Example 5:

[0058] S1: Add 2.0g of adhesive to 100g of solvent and stir until completely dissolved to obtain adhesive solution;

[0059] S2: Add 5.0g of nano silicon carbide particles and 2.5g of silicon carbide whiskers to 102g of adhesive solution in a certain proportion, and stir and disperse at high speed for 30 minutes to form a thermally conductive adhesive solution.

[0060] S3: Add 2.0g of conductive agent to 109.5g of thermally conductive adhesive and continue to disperse for 30 minutes to form a conductive and thermally conductive slurry;

[0061] S4: Add 88.5 g of active material to 111.5 g of conductive and thermally conductive slurry, stir and disperse for 60 minutes, and adjust the viscosity to 3000~5000 mPa·s to obtain the electrode slurry. Coat the electrode slurry onto the surface of the current collector, control the coating thickness to 150 μm, and obtain a battery electrode containing composite nano-silicon carbide after drying and rolling.

[0062] Comparative Example 1:

[0063] S1: Add 2.0g of adhesive to 100g of solvent and stir until completely dissolved to obtain adhesive solution.

[0064] S2: Add 2.0g of nano-silicon carbide particles to 102g of adhesive liquid, stir and disperse at high speed for 30 minutes to form a thermally conductive adhesive liquid.

[0065] S3: Add 2.0g of conductive agent to 104g of thermally conductive adhesive and continue to stir and disperse at high speed for 30 minutes to form a conductive and thermally conductive slurry.

[0066] S4: Add 94.0g of active material to 106g of conductive and thermally conductive slurry, stir and disperse at high speed for 60 minutes, and adjust the viscosity to 3000~5000mPa·s to obtain the electrode slurry. Coat the electrode slurry onto the surface of the current collector, control the coating thickness to 150um, and after drying and rolling, obtain the battery electrode containing composite nano-silicon carbide.

[0067] Comparative Example 2:

[0068] S1: Add 2.0g of adhesive to 100g of solvent and stir until completely dissolved to obtain adhesive solution.

[0069] S2: Add 1.0g of nano silicon carbide whiskers to 102g of adhesive liquid, stir and disperse at high speed for 30 minutes to form a thermally conductive adhesive liquid.

[0070] S3: Add 2.0g of conductive agent to 103g of thermally conductive adhesive and continue to disperse for 30 minutes to form a conductive and thermally conductive slurry.

[0071] S4: Add 94.0g of active material to 105g of conductive and thermally conductive slurry, stir and disperse at high speed for 60 minutes, and adjust the viscosity to 3000~5000mPa·s to obtain the electrode slurry. Coat the electrode slurry onto the surface of the current collector, control the coating thickness to 150um, and after drying and rolling, obtain the battery electrode containing composite nano-silicon carbide.

[0072] Comparative Example 3:

[0073] S1: Add 2.0g of adhesive to 100g of solvent and stir until completely dissolved to obtain adhesive solution.

[0074] S2: Add 2.0g of conductive agent to 102g of thermally conductive adhesive and continue to disperse for 30 minutes to form a conductive and thermally conductive slurry.

[0075] S3: Add 96.0g of active material to 104g of conductive slurry, stir at high speed for 60 minutes to disperse, and adjust the viscosity to 3000~5000mPa·s to obtain electrode slurry. Coat the electrode slurry onto the surface of the current collector, control the coating thickness to 150um, and obtain a battery electrode containing composite nano-silicon carbide after drying and rolling.

[0076] The performance tests of the batteries prepared in the above embodiments and comparative examples are shown in the table below:

[0077] Table 1 Battery Performance Test Table

[0078]

[0079] As shown in Table 1, the electrode batteries prepared in Examples 1, 2, and 3 all exhibited low temperature rises at both 2C and 5C discharge rates. Data from Comparative Example 3 indicates that the temperature rise of the electrode battery without a thermally conductive agent was relatively high. Data from Comparative Examples 2 and 3 show that adding silicon carbide particles or whiskers alone reduced the temperature rise somewhat compared to Comparative Example 3, but the effect was not significant. The data in Table 1 demonstrate that the appropriate addition of silicon carbide particles and whiskers can effectively enhance the heat dissipation capacity of sodium-ion batteries.

[0080] The present invention Figure 2 The large blue spherical substances are active material particles, the small black spherical substances are silicon carbide particles, and the long whiskers are silicon carbide whiskers.

[0081] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a sodium-ion battery electrode containing composite nano-silicon carbide, characterized in that, Includes the following steps: S1: Add 1-5 parts by weight of adhesive to 100 parts by weight of solvent, stir evenly to obtain adhesive solution; S2: Add 0.5~5.5 parts by weight of nano-silicon carbide particles and 0.5~5.5 parts by weight of silicon carbide whiskers to the adhesive solution, wherein the nano-silicon carbide particles and silicon carbide whiskers are added to the adhesive solution in a weight ratio of 1~2:1 and dispersed evenly to form a thermally conductive adhesive solution; S3: Add 0.5-6 parts by weight of conductive agent to 100 parts of thermally conductive adhesive and disperse evenly to form a conductive and thermally conductive slurry; S4: Add 60-200 parts by weight of active material to 100 parts of conductive and thermally conductive slurry, and disperse and homogenize to obtain electrode slurry; Electrode slurry is coated onto the surface of the current collector with a coating thickness of 100 μm to 300 μm to obtain a battery electrode containing composite nano-silicon carbide.

2. The method for preparing a sodium-ion battery electrode containing composite nano-silicon carbide according to claim 1, characterized in that, The particle size of the active substance is 5µm to 10µm.

3. The method for preparing a sodium-ion battery electrode containing composite nano-silicon carbide according to claim 1, characterized in that, The coating thickness of the battery electrode containing composite nano-silicon carbide is 100um~300um.

4. The method for preparing a sodium-ion battery electrode containing composite nano-silicon carbide according to claim 1, characterized in that, The electrode slurry has a solid content of 40wt% to 65wt% and a viscosity of 3000mPa·s to 5000mPa·s.

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