Solid electrolyte-containing interface modified silicon-carbon composite negative electrode material and preparation method and application thereof
By introducing lithium aluminum titanium phosphate (LATP) into the nano-silicon-expanded graphite composite material, a solid electrolyte interface is formed, which solves the pulverization problem caused by volume change of silicon-based anode materials and improves cycle stability and electrochemical performance.
Patent Information
- Application Number
- CN202511196814.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-26
- Publication Date
- 2025-11-28
AI Technical Summary
Existing silicon-based anode materials in lithium-ion batteries suffer from particle pulverization due to volume expansion and contraction, resulting in loss of electrical contact, capacity loss, and cycle life degradation. Furthermore, the SEI film is unstable, consumes electrolyte, and affects lithium-ion transport.
A nano-silicon-expanded graphite composite material modified with lithium aluminum titanium phosphate (LATP) is used to form a solid electrolyte interface through high-temperature treatment and vacuum carbonization, which alleviates volume changes, enhances conductivity, and stabilizes the SEI film.
It improves the cycle life and initial charge/discharge efficiency of the material, enhances lithium-ion transport, and improves electrochemical and rate performance.
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Figure CN121035211A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of battery technology, and particularly relates to a silicon-carbon composite anode material with solid electrolyte interface modification, its preparation method and application. Background Technology
[0002] Silicon intercalates lithium by forming lithium-silicon alloys. This intercalation process involves significant volume expansion, while de-lithiation and dealloying result in dramatic volume contraction—a change of up to 300%. This volume shift easily leads to silicon pulverization, severely impacting cycle stability. Preparing appropriately sized nano-silicon powder can effectively address this particle pulverization during electrochemical cycling. However, the significant volume change effect after lithium intercalation in nano-silicon still exists. Repeated expansion and contraction of the electrode can cause particles to lose electrical contact and pulverize, resulting in capacity loss and reduced cycle life.
[0003] Using existing, commercially available graphite-based anode materials as a framework to composite nano-silicon materials to overcome the inherent shortcomings of silicon-based materials and obtain novel composite anode materials with the specific capacity and cycle life required for lithium-ion batteries is an effective and feasible low-cost method. However, when nano-silicon is combined with expanded graphite, the expansion and contraction rates of lithium insertion / extraction are inconsistent, which can easily lead to the loss of electrical contact between the nano-silicon particles, resulting in capacity loss. At the same time, the SEI film formed on the surface is unstable, continuously consuming electrolyte and hindering lithium-ion transport in the battery, resulting in a low coulombic efficiency in the first cycle and thus a decrease in the cycle life of the material.
[0004] Therefore, how to provide a negative electrode material that can mitigate material volume changes while having a higher cycle life is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention proposes a silicon-carbon composite anode material with solid electrolyte interface modification, its preparation method, and its application.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] The first aspect of this invention provides a silicon-carbon composite anode material with solid electrolyte interface modification, comprising the following raw materials by mass fraction:
[0008] Lithium aluminum titanium phosphate 0.5-10 wt.%, nano-silicon-expanded graphite composite material 90-99.5%.
[0009] Beneficial effects: The lithium aluminum titanium phosphate in this invention has high ionic conductivity, which can effectively reduce the internal resistance of silicon-based materials, making lithium ion transport within the battery smoother and improving the battery's charge-discharge efficiency and rate performance. Simultaneously, the composite anode material prepared by this invention is close to the nanoscale, allowing for better coating and ensuring sufficient contact between the anode material and the electrolyte, thus improving electrochemical performance.
[0010] Preferably, the nano-silicon-expanded graphite composite material comprises the following raw materials in the indicated mass fractions:
[0011] Sodium carboxymethyl cellulose 1-5 wt.%, expanded graphite 35-44 wt.%, and spherical nano-silicon 55-60 wt.
[0012] Beneficial effects: The sodium carboxymethyl cellulose in this invention can be well adsorbed onto the particle surface, weakening the interaction between particles, effectively preventing particle agglomeration, and ensuring uniform dispersion of particles in the system. Simultaneously, it can effectively wet the particles, which is beneficial for their uniform dispersion and stable existence in the solvent. Furthermore, expanded graphite has a more pronounced layered structure and a higher half-maximum width at half-maximum (HWHM), which can provide better resilience to the interlayer nano-silicon in the composite material, offering a new feasibility for mitigating silicon volume expansion. At the same time, the high conductivity of expanded graphite can further improve the rate performance, charge-discharge efficiency, and cycle stability of the composite material.
[0013] Preferably, the preparation method of the nano-silicon-expanded graphite composite material includes the following steps:
[0014] Nano-silicon powder was evenly dispersed in sodium carboxymethyl cellulose solution, and then expanded graphite was added to obtain a suspension. After freeze-drying, a precursor of nano-silicon-expanded graphite composite material was obtained.
[0015] The precursor of the nano-silicon-expanded graphite composite material is obtained by vacuum carbonization.
[0016] Beneficial effects: The vacuum environment in the above-mentioned vacuum carbonization process can prevent the precursor from reacting with oxygen in the air during carbonization, thus preventing the oxidation of nano-silicon and expanded graphite and ensuring that the material's performance is not affected by oxidation. This is especially crucial for easily oxidized materials like nano-silicon. Furthermore, vacuum carbonization causes the pyrolysis of sodium carboxymethyl cellulose to form a conductive network, which can more firmly bond nano-silicon and expanded graphite together, improving their conductivity, enhancing the structural stability of the composite material, and reducing particle shedding during cycling.
[0017] Preferably, the solid content of the suspension is 10-15 wt.%.
[0018] Preferably, the freeze-drying temperature is -90 to -110°C, and the time is 22-26 hours.
[0019] Preferably, the vacuum carbonization temperature is 800-1200℃ and the time is 3-6h.
[0020] A second aspect of this invention provides a method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification, comprising the following steps:
[0021] The silicon-carbon composite anode material is obtained by mixing the lithium aluminum titanium phosphate and the nano-silicon-expanded graphite composite material and then treating it at high temperature.
[0022] Beneficial effects: The above preparation method enables LATP to better integrate with composite materials, increases structural order, and improves the rate performance of the materials.
[0023] Preferably, the high-temperature treatment is performed at a temperature of 600-800℃ for 3-6 hours.
[0024] Beneficial effects: Lithium aluminum titanium phosphate will decompose and denature above 800°C. Therefore, the high-temperature treatment temperature in this invention cannot exceed 800°C.
[0025] The third aspect of this invention provides the application of a silicon-carbon composite anode material with solid electrolyte interface modification in lithium battery anodes.
[0026] Compared with the prior art, the present invention has the following advantages and technical effects:
[0027] This invention utilizes lithium aluminum titanium phosphate (LATP) modification to effectively mitigate the volume expansion of the anode material and stabilize the SEI film formed on the material surface. Simultaneously, LATP acts as a lithium replenisher for pre-lithiation, compensating for losses during the first stage of efficiency. Building upon the preparation of nano-silicon-expanded graphite composite anode materials using nano-silicon and expanded graphite composites, this invention enhances the conductivity of nano-silicon particles and stabilizes the SEI film through an LATP modification layer, thereby mitigating material volume changes and achieving a composite anode material with higher cycle life. The preparation method provided by this invention is simple and easy to promote and apply. Attached Figure Description
[0028] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:
[0029] Figure 1 The energy dispersive spectroscopy (EDS) diagram of the composite anode material obtained in Example 1 of this invention is shown below.
[0030] Figure 2 The graph shows the capacity retention rate of the 2032 coin cell prepared from the negative electrode materials obtained in Example 1 and Comparative Example 1 of this invention. Detailed Implementation
[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0033] This invention discloses a silicon-carbon composite anode material with solid electrolyte interface modification, comprising the following raw materials by mass fraction:
[0034] Lithium aluminum titanium phosphate 0.5-10 wt.%, nano-silicon-expanded graphite composite material 99.5-90%.
[0035] In an optional embodiment, the silicon-carbon composite anode material with solid electrolyte interface modification comprises the following raw materials by mass fraction: 0.5 wt.% lithium aluminum titanium phosphate and 99.5% nano-silicon-expanded graphite composite material.
[0036] In another optional embodiment, the silicon-carbon composite anode material with solid electrolyte interface modification comprises the following raw materials in mass fractions: 1 wt.% lithium aluminum titanium phosphate and 99% nano-silicon-expanded graphite composite material.
[0037] In another optional embodiment, the silicon-carbon composite anode material with solid electrolyte interface modification comprises the following raw materials in mass fractions: 10 wt.% lithium aluminum titanium phosphate and 90% nano-silicon-expanded graphite composite material.
[0038] In another optional embodiment, the silicon-carbon composite anode material with solid electrolyte interface modification comprises the following raw materials in mass fractions: 6 wt.% lithium aluminum titanium phosphate and 94% nano-silicon-expanded graphite composite material.
[0039] In a preferred embodiment, the nano-silicon-expanded graphite composite material comprises the following raw materials by mass fraction: 1-5 wt.% sodium carboxymethyl cellulose, 35-44 wt.% expanded graphite, and 55-60 wt.% spherical nano-silicon.
[0040] Optionally, the nano-silicon-expanded graphite composite material comprises the following raw materials in mass fractions: 5 wt.% sodium carboxymethyl cellulose, 35 wt.% expanded graphite, and 60 wt.% spherical nano-silicon.
[0041] In another optional embodiment, the nano-silicon-expanded graphite composite material comprises the following raw materials in mass fractions: 1 wt.% sodium carboxymethyl cellulose, 44 wt.% expanded graphite, and 55 wt.% spherical nano-silicon.
[0042] In another optional embodiment, the nano-silicon-expanded graphite composite material comprises the following raw materials in mass fractions: 3 wt.% sodium carboxymethyl cellulose, 40 wt.% expanded graphite, and 57 wt.% spherical nano-silicon.
[0043] This invention also discloses a method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification, comprising the following steps:
[0044] The silicon-carbon composite anode material is obtained by mixing the lithium aluminum titanium phosphate and the nano-silicon-expanded graphite composite material and then treating it at high temperature.
[0045] In a preferred embodiment, the high-temperature treatment is performed at a temperature of 600-800℃ for 3-6 hours. For example, 800℃ for 3 hours; or 600℃ for 6 hours; or 800℃ for 6 hours; or 700℃ for 4 hours.
[0046] In a preferred embodiment, the preparation method of the nano-silicon-expanded graphite composite material includes the following steps:
[0047] Nano-silicon powder was evenly dispersed in sodium carboxymethyl cellulose solution, and then expanded graphite was added to obtain a suspension. After freeze-drying, a precursor of nano-silicon-expanded graphite composite material was obtained.
[0048] The precursor of the nano-silicon-expanded graphite composite material is obtained by vacuum carbonization.
[0049] In a preferred embodiment, the solid content of the suspension is 10-15 wt.%.
[0050] In a preferred embodiment, the freeze-drying temperature is 900-110°C and the time is 22-26 hours.
[0051] In a preferred embodiment, the vacuum carbonization temperature is 800-1200℃ and the time is 3-6 hours.
[0052] This invention also discloses the application of a silicon-carbon composite anode material with solid electrolyte interface modification in lithium battery anodes.
[0053] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels;
[0054] Unless otherwise specified, room temperature or ambient temperature in the embodiments of the present invention refers to 25±3℃, and there are no specific requirements for the stirring rate of "high-speed stirring" in the embodiments of the present invention. The "high-speed stirring" in the embodiments of the present invention usually reaches 1000r / min in laboratory preparation.
[0055] Example 1
[0056] A method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification includes the following steps:
[0057] 1) Weigh 15g of sodium carboxymethyl cellulose (CMC) powder and add it to 1700g of deionized water and stir to disperse it to obtain a CMC aqueous solution. Weigh 180g of spherical nano-silica powder and add it to the CMC aqueous solution, stir to disperse it, and obtain a suspension of nano-silica powder.
[0058] 2) Stir the suspension obtained in step 1) at high speed, and add 105g of expanded graphite powder at the same time. Stir and mix thoroughly to obtain a uniform slurry with a solid content of 15wt.%.
[0059] 3) The uniform slurry obtained in step 2) was placed in a freezer for pre-freezing for 6 hours. Then, the pre-frozen sample was transferred to a vacuum freeze dryer and the freeze-drying time was controlled at 24 hours. The cold trap temperature was controlled at -100℃ to obtain the precursor of nano-silicon-expanded graphite composite material. Then, it was transferred to a vacuum furnace for high-temperature carbonization at 1200℃ for 6 hours. After cooling, it was taken out, crushed and sieved to obtain nano-silicon-expanded graphite composite anode material.
[0060] 4) Weigh 2g of lithium aluminum titanium phosphate (LATP) powder and 198g of the nano-silicon-expanded graphite composite anode material obtained in step 3) and add them together into a mechanical fusion machine. Fuse at high speed for 20 minutes to obtain the LATP-modified precursor.
[0061] 5) The LATP-modified precursor obtained in step 4) was transferred into a vacuum furnace and carbonized at 800°C for 3 hours to obtain a nano-silicon-expanded graphite composite anode material with a 1wt.% LATP-modified layer.
[0062] Example 2
[0063] A method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification includes the following steps:
[0064] 1) Weigh 15g of sodium carboxymethyl cellulose (CMC) powder and add it to 2700g of deionized water and stir to disperse it to obtain a CMC aqueous solution. Weigh 180g of nano-silicon powder and add it to the CMC aqueous solution, stir to disperse it, and obtain a suspension of nano-silicon powder.
[0065] 2) Stir the suspension obtained in step 1) at high speed, and add 105g of expanded graphite powder at the same time. Stir and mix thoroughly to obtain a uniform slurry with a solid content of 10wt.%.
[0066] 3) The uniform slurry obtained in step 2) was placed in a freezer for pre-freezing for 6 hours. Then, the pre-frozen sample was transferred to a vacuum freeze dryer and the freeze-drying time was controlled at 24 hours. The cold trap temperature was controlled at -100℃ to obtain the precursor of nano-silicon-expanded graphite composite material. Then, it was transferred to a vacuum furnace for high-temperature carbonization at 1200℃ for 6 hours. After cooling, it was taken out, crushed and sieved to obtain nano-silicon-expanded graphite composite anode material.
[0067] 4) Weigh 1g of lithium aluminum titanium phosphate (LATP) powder and 199g of the nano-silicon-expanded graphite composite anode material obtained in step 3) and add them together into a mechanical fusion machine. Fuse at high speed for 20 minutes to obtain the LATP-modified precursor.
[0068] 5) The LATP-modified precursor obtained in step 4) was transferred into a vacuum furnace and carbonized at 600°C for 6 hours to obtain a nano-silicon-expanded graphite composite anode material with a 0.5 wt.% LATP-modified layer.
[0069] Example 3
[0070] A method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification includes the following steps:
[0071] 1) Weigh 3g of sodium carboxymethyl cellulose (CMC) powder and add it to 2100g of deionized water and stir to disperse it to obtain a CMC aqueous solution. Weigh 165g of nano-silicon powder and add it to the CMC aqueous solution, stir to disperse it, and obtain a suspension of nano-silicon powder.
[0072] 2) Stir the suspension obtained in step 1) at high speed, and add 132g of expanded graphite powder at the same time. Stir and mix thoroughly to obtain a uniform slurry with a solid content of 12.5wt.%.
[0073] 3) The uniform slurry obtained in step 2) was placed in a freezer for pre-freezing for 6 hours. Then, the pre-frozen sample was transferred to a vacuum freeze dryer and the freeze-drying time was controlled at 24 hours. The cold trap temperature was controlled at -100°C to obtain the precursor of nano-silicon-expanded graphite composite material. Then, it was transferred to a vacuum furnace and carbonized at 800°C for 3 hours. After cooling, it was taken out, crushed and sieved to obtain nano-silicon-expanded graphite composite anode material.
[0074] 4) Weigh 20g of lithium aluminum titanium phosphate (LATP) powder and 180g of the nano-silicon-expanded graphite composite anode material obtained in step 3) and add them together into a mechanical fusion machine. Fuse at high speed for 20 minutes to obtain the LATP-modified precursor.
[0075] 5) The LATP-modified precursor obtained in step 4) was transferred into a vacuum furnace and carbonized at 800°C for 6 hours to obtain a nano-silicon-expanded graphite composite anode material with a 10wt.% LATP-modified layer.
[0076] Example 4
[0077] A method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification includes the following steps:
[0078] 1) Weigh 9g of sodium carboxymethyl cellulose (CMC) powder and add it to 1700g of deionized water and stir to disperse it to obtain a CMC aqueous solution. Weigh 171g of nano-silicon powder and add it to the CMC aqueous solution, stir to disperse it, and obtain a suspension of nano-silicon powder.
[0079] 2) Stir the suspension obtained in step 1) at high speed, and add 120g of expanded graphite powder at the same time. Stir and mix thoroughly to obtain a uniform slurry with a solid content of 15wt.%.
[0080] 3) The uniform slurry obtained in step 2) was placed in a freezer for pre-freezing for 6 hours. Then, the pre-frozen sample was transferred to a vacuum freeze dryer and the freeze-drying time was controlled at 24 hours. The cold trap temperature was controlled at -100°C to obtain the precursor of nano-silicon-expanded graphite composite material. Then, it was transferred to a vacuum furnace and carbonized at 800°C for 3 hours. After cooling, it was taken out, crushed and sieved to obtain nano-silicon-expanded graphite composite anode material.
[0081] 4) Weigh 12g of lithium aluminum titanium phosphate (LATP) powder and 188g of the nano-silicon-expanded graphite composite anode material obtained in step 3) and add them together into a mechanical fusion machine. Fuse at high speed for 20 minutes to obtain the LATP-modified precursor.
[0082] 5) The LATP-modified precursor obtained in step 4) was transferred into a vacuum furnace and carbonized at 700°C for 4 hours to obtain a nano-silicon-expanded graphite composite anode material with a 6wt.% LATP-modified layer.
[0083] Comparative Example 1
[0084] A method for preparing a silicon-carbon composite anode material includes the following steps:
[0085] 1) Weigh 15g of sodium carboxymethyl cellulose (CMC) powder and add it to 2000g of deionized water and stir to disperse it to obtain a CMC aqueous solution. Weigh 180g of nano-silicon powder and add it to the CMC aqueous solution, stir to disperse it, and obtain a suspension of nano-silicon powder.
[0086] 2) Stir the suspension obtained in step 1) at high speed, and add 105g of expanded graphite powder at the same time. Stir and mix thoroughly to obtain a uniform slurry with a solid content of 13wt.%.
[0087] 3) The uniform slurry obtained in step 2) was placed in a freezer for pre-freezing for 6 hours. Then, the pre-frozen sample was transferred to a vacuum freeze dryer and the freeze-drying time was controlled at 24 hours. The cold trap temperature was controlled at -100℃ to obtain the precursor of nano-silicon-expanded graphite composite material. Then, it was transferred to a vacuum furnace for high-temperature carbonization at 1200℃ for 6 hours. After cooling, it was taken out, crushed and sieved to obtain nano-silicon-expanded graphite composite anode material.
[0088] Comparative Example 2
[0089] A method for preparing a negative electrode material differs from Example 1 only in that expanded graphite is not added, i.e., step (2) is not included; all other process steps and parameters are the same as in Example 1. Specifically, it includes the following steps:
[0090] 1) Weigh 15g of sodium carboxymethyl cellulose (CMC) powder and add it to 1700g of deionized water and stir to disperse it to obtain a CMC aqueous solution. Weigh 180g of spherical nano-silica powder and add it to the CMC aqueous solution, stir to disperse it, and obtain a suspension of nano-silica powder.
[0091] 2) The suspension of nano-silicon powder obtained in step 1) was placed in a freezer for pre-freezing for 6 hours. Then, the pre-frozen sample was transferred to a vacuum freeze dryer and the freeze-drying time was controlled at 24 hours. The cold trap temperature was controlled at -100°C to obtain the nano-silicon precursor. The precursor was then transferred to a vacuum furnace and carbonized at 1200°C for 6 hours. After cooling, it was taken out, crushed, and sieved to obtain the nano-silicon anode material.
[0092] 3) Weigh 2g of lithium aluminum titanium phosphate (LATP) powder and 198g of the nano-silicon anode material obtained in step 2) and add them together into a mechanical fusion machine. Fuse at high speed for 20 minutes to obtain the LATP-modified precursor.
[0093] 4) The LATP-modified precursor obtained in step 3) was transferred into a vacuum furnace and carbonized at 800°C for 3 hours to obtain a nano-silicon composite anode material with a 1wt.% LATP-modified layer.
[0094] Comparative Example 3
[0095] A method for preparing a negative electrode material, differing from Example 1 only in that step 3) does not include high-temperature carbonization, and specifically includes the following steps:
[0096] 1) Weigh 15g of sodium carboxymethyl cellulose (CMC) powder and add it to 1700g of deionized water and stir to disperse it to obtain a CMC aqueous solution. Weigh 180g of nano-silicon powder and add it to the CMC aqueous solution, stir to disperse it, and obtain a suspension of nano-silicon powder.
[0097] 2) Stir the suspension obtained in step 1) at high speed, and add 105g of expanded graphite powder at the same time. Stir and mix thoroughly to obtain a uniform slurry with a solid content of 15wt.%.
[0098] 3) Place the uniform slurry obtained in step 2) into a freezer for pre-freezing for 6 hours. Then transfer the pre-frozen sample into a vacuum freeze dryer and control the freeze-drying time to 24 hours. The cold trap temperature is controlled at -100℃ to obtain the precursor of nano-silicon-expanded graphite composite anode material.
[0099] 4) Weigh 2g of lithium aluminum titanium phosphate (LATP) powder and 198g of the nano-silicon-expanded graphite composite anode material precursor obtained in step 3) and add them together into a mechanical fusion machine. Fuse at high speed for 20 minutes to obtain the LATP-modified precursor.
[0100] 5) The LATP-modified precursor obtained in step 4) is transferred into a vacuum furnace and carbonized at 800°C for 3 hours to obtain a nano-silicon-expanded graphite composite anode material with an LATP-modified layer.
[0101] Technical effects:
[0102] 1. Energy dispersive spectroscopy (EDS)
[0103] Energy dispersive spectroscopy (EDS) analysis of the composite anode material obtained in Example 1 is as follows: Figure 1 As shown, the LATP-modified sample contains uniformly distributed Al and Ti elements. The introduction of LATP can improve ionic conductivity, enhance interfacial stability, and increase the cycling stability of the material. On the other hand, the Al and Ti elements can enhance electrical conductivity, improve the rate performance and cycling stability of the material, which is consistent with the cycling results in Table 1 below.
[0104] 2. Electrochemical performance
[0105] The nano-silicon-expanded graphite composite anode materials obtained in Examples 1-4 and Comparative Examples 1-3 were prepared into anode sheets, specifically including the following steps:
[0106] The nano-silicon-expanded graphite composite anode materials (80 wt.%) obtained in Examples 1-4 and Comparative Examples 1-3, Super-P conductive agent (10 wt.%), and binder (SBR:CMC = 2:3) (10 wt.%) were mixed in deionized water to form a slurry. The slurry was uniformly coated on copper foil, then dried in a vacuum at 80°C for 24 hours, and then pressed and punched into a 12 mm diameter anode sheet.
[0107] The negative electrode sheets were assembled into 2032 coin cells, and their cycle life was tested. Material performance data are shown in Table 1, and the cycle life curves are shown below. Figure 2 As shown. The test method for battery cycle performance is as follows: first, discharge at a current density of 200mA / g to 0.005V, let stand for 3 minutes, and then charge at a current density of 200mA / g to 1.5V. This constitutes one cycle test for cycle performance.
[0108] Table 1
[0109]
[0110] Depend on Figure 2 As can be seen, the first-efficiency and cycling performance of the material are significantly improved after modification with lithium aluminum titanium phosphate composite. Table 1 shows that, compared to Comparative Example 1, the first-efficiency of Examples 1-4 is significantly improved, reaching approximately 90%. This indicates that the material forms a more stable SEI film, which is beneficial for suppressing electrolyte decomposition and its side reactions with the electrode, thus improving rate performance. Furthermore, the capacity retention rate of the LATP-modified samples is significantly improved compared to Comparative Example 1, increasing from 22.36% to over 70%. The cycling stability of the material is greatly improved, and its lifespan and safety are correspondingly guaranteed.
[0111] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A silicon-carbon composite anode material with solid electrolyte interface modification, characterized in that, Raw materials including the following mass fractions: Lithium aluminum titanium phosphate 0.5-10 wt.%, nano-silicon-expanded graphite composite material 99.5-90%.
2. The silicon-carbon composite anode material with solid electrolyte interface modification according to claim 1, characterized in that, The nano-silicon-expanded graphite composite material comprises the following raw materials by mass fraction: Sodium carboxymethyl cellulose 1-5 wt.%, expanded graphite 35-44 wt.%, and spherical nano-silicon 55-60 wt.
3. The silicon-carbon composite anode material with solid electrolyte interface modification according to claim 2, characterized in that, The preparation method of the nano-silicon-expanded graphite composite material includes the following steps: Nano-silicon powder was evenly dispersed in sodium carboxymethyl cellulose solution, and then expanded graphite was added to obtain a suspension. After freeze-drying, a precursor of nano-silicon-expanded graphite composite material was obtained. The precursor of the nano-silicon-expanded graphite composite material is obtained by vacuum carbonization.
4. The method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification according to claim 3, characterized in that, The solid content of the suspension is 10-15 wt.%.
5. The method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification according to claim 3, characterized in that, The freeze-drying temperature is -90 to -110°C, and the time is 22-26 hours.
6. The method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification according to claim 6, characterized in that, The vacuum carbonization temperature is 800-1200℃, and the time is 3-6 hours.
7. A method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification as described in any one of claims 1 to 6, characterized in that, Includes the following steps: The silicon-carbon composite anode material is obtained by mixing the lithium aluminum titanium phosphate and the nano-silicon-expanded graphite composite material and then treating it at high temperature.
8. The method for preparing a silicon-carbon composite anode material with solid electrolyte interface modification according to claim 7, characterized in that, The high-temperature treatment is performed at a temperature of 600-800℃ for 3-6 hours.
9. The application of the silicon-carbon composite anode material with solid electrolyte interface modification as described in any one of claims 1 to 6 in the preparation of lithium battery anodes.