A pre-lithiated SiOx composite electrode material, its preparation method and application

Abstract

This invention discloses a pre-lithiated SiOx composite electrode material, its preparation method, and its applications, belonging to the field of material preparation technology. The preparation method includes: pre-treating a silicon oxide precursor with milling beads using a wet ball milling process under an inert atmosphere; forming a dispersion system by dispersing a metal salt and a fibrous template material in a lithium hydroxide solution; mixing the two systems and then inducing precipitation with an alcohol solvent to form a precursor; finally, acid treatment, washing, drying, and high-temperature carbonization under a protective atmosphere to obtain the final composite material. This material has a porous structure, with silicon oxide uniformly embedded in a highly graphitized carbon matrix. This invention features a simple process, stable interfacial bonding, effectively solves the volume expansion problem of silicon-based materials, and significantly improves electrochemical performance and cycle stability, making it particularly suitable as a negative electrode material for electrochemical energy storage devices such as lithium-ion batteries.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, and more specifically, to a pre-lithiated SiOx composite electrode material, its preparation method, and its application. Background Technology

[0002] In recent years, with the rapid development of portable electronic devices, electric vehicles, and large-scale energy storage systems, the market demand for high-energy-density lithium-ion batteries has become increasingly urgent. Silicon-based materials (such as silicon suboxide SiOx) are considered one of the most promising next-generation anode materials due to their ultra-high theoretical specific capacity (approximately 2600 mAh / g), low lithium intercalation potential, and abundant resource reserves. They have already shown broad application prospects in the field of high-energy-density batteries.

[0003] However, silicon-based materials still face severe challenges in their commercialization: during charge and discharge, they exhibit a huge volume expansion effect (up to 100% or more), which easily leads to electrode material pulverization and active material shedding, severely deteriorating cycle stability; simultaneously, the intrinsic electronic conductivity of silicon-based materials is poor, limiting their high-rate performance. Furthermore, the surface of silicon-based materials is rich in silanol groups, which easily react with the electrolyte, resulting in low initial coulombic efficiency. To overcome these problems, traditional modification methods mainly involve introducing carbon matrix or metal oxides for composite modification to buffer volume changes and improve conductivity. However, existing composite modification processes are often cumbersome, energy-intensive, and the interfacial bonding strength in the composite material is insufficient, making it difficult to maintain stable electrochemical performance during long-term cycling. Therefore, developing a silicon-based composite material that can simultaneously control the alkaline residue on the surface of pre-lithiated silicon-based materials, optimize the dispersion state of silicon particles, achieve strong interfacial bonding, and possess excellent electrochemical performance is of significant practical importance for promoting the development of high-energy-density lithium-ion batteries.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a pre-lithiated SiOx composite electrode material, its preparation method and application, and to improve its electrochemical performance and cycle stability by optimizing the material structure and interface design.

[0006] This invention is implemented as follows: In a first aspect, the present invention provides a pre-lithiated SiOx composite electrode material, the material comprising: a carbon fiber matrix, SiOx particles uniformly dispersed in the carbon fiber matrix, and a cellulose-metal chelate coating layer covering the surface of the carbon fiber matrix.

[0007] In an optional embodiment, the SiOx particles have a particle size of 0.5-2 μm, and the carbon fiber matrix has a porosity of 60-80%.

[0008] In an optional embodiment, the material has an initial discharge capacity ≥1400mAh / g and an initial coulombic efficiency ≥80%.

[0009] In an optional embodiment, the material further includes a single-walled carbon nanotube additive, added in an amount of 0.1%-2% of the total mass.

[0010] Secondly, the present invention provides a method for preparing a pre-lithiated SiOx composite electrode material, comprising the following steps: wet ball milling of a silicon oxide precursor, copper-based carbonate, and carbon fiber in an organic solvent under an inert atmosphere, followed by drying to obtain a pretreated powder; forming a uniform dispersion of a metal salt and a fibrous template material in a lithium hydroxide solution; dispersing the pretreated powder in water, adding a surfactant and stirring to form a uniform suspension, then mixing it with the dispersion, and adding it dropwise to an alcohol solvent and allowing it to stand to form a precursor precipitate; mixing the precipitate with a fast ion conductive coating material, followed by acid treatment and drying, and then high-temperature carbonization under a protective atmosphere to obtain the pre-lithiated SiOx composite electrode material.

[0011] In an optional embodiment, the amount of carbon fiber added is 20%-30% of the mass of the silicon oxide precursor; And / or, the ball milling time is 6-12 hours, and the ball-to-material ratio is in the range of (10-20):1.

[0012] In an optional embodiment, the metal salt is at least one selected from iron, aluminum, copper, or nickel salts, and the amount of the metal salt added is 1-5% of the mass of the fibrous template material. And / or, the fibrous template material is selected from at least one of cotton fiber, chitosan, alginate or PVA, and the concentration of its dispersion is controlled at 1:10-1:40 g / mL.

[0013] In an optional embodiment, the acid treatment uses hydrochloric acid for washing, the volume ratio of the hydrochloric acid solution is 1:(1-50), and the number of washing cycles is 1-3.

[0014] In an optional embodiment, the fast ion conductor coating material is Al2O3 or M33 type conductive agent; And / or, the carbonization temperature is 700-900℃, and the heating rate is 2-5℃ / min.

[0015] Thirdly, the present invention provides a lithium-ion battery that uses the above-mentioned pre-lithiated SiOx composite electrode material as the negative electrode active material, and the battery retains ≥85% of its capacity after 200 cycles at 1C rate.

[0016] The present invention has the following beneficial effects: This invention achieves uniform mixing of components by wet ball milling pretreatment of silicon oxide, copper-based carbonate, and carbon fiber. Simultaneously, the copper-based carbonate decomposes and forms pores during carbonization, effectively buffering the volume expansion of the silicon-based material and significantly improving the structural stability and cycle life of the electrode. Secondly, the introduction of a cellulose-metal chelate coating layer forms a uniform and dense coating layer on the surface of the carbon fiber matrix, enhancing the bonding strength of the material interface and avoiding the problem of easy interface peeling in traditional composite methods. Furthermore, this coating layer transforms into a carbon layer after carbonization, further improving the conductivity of the material. In addition, the preparation method is simple and controllable, suitable for large-scale production. In the final composite material, SiOx particles are uniformly dispersed in the carbon fiber matrix, synergistically leveraging the high capacity of silicon and the conductivity and buffering advantages of carbon, resulting in excellent electrochemical performance and promising practical application prospects. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the preparation process of the pre-lithiated SiOx composite electrode material in this embodiment of the invention. Figure 2 This is an electron microscope image of the surface morphology of the electrode material in an embodiment of the present invention; Figure 3 This is a comparison chart of the rate performance of composite electrode materials in the embodiments of the present invention; Figure 4 This is a comparison chart of charge-discharge curves of the composite electrode materials in the embodiments of the present invention; Figure 5 This is the Raman spectrum of the composite electrode material in an embodiment of the present invention; Figure 6 This is a comparison chart of the cyclic stability of composite electrode materials in the embodiments of the present invention; Figure 7 This is the in-situ electrochemical impedance spectroscopy of the composite electrode material in an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0020] The following provides a detailed description of a pre-lithiated SiOx composite electrode material, its preparation method, and its application.

[0021] In a first aspect, the present invention provides a pre-lithiated SiOx composite electrode material, the material comprising: a carbon fiber matrix, SiOx particles uniformly dispersed in the carbon fiber matrix, and a cellulose-metal chelate coating layer covering the surface of the carbon fiber matrix.

[0022] In some preferred embodiments, SiOx particles are uniformly dispersed in the carbon fiber matrix, synergistically leveraging the high capacity of silicon and the conductivity and buffering advantages of carbon, enabling the electrode material to exhibit excellent electrochemical performance and showing promising prospects for practical application.

[0023] Specifically, the composite material has a porous structure with silicon oxide uniformly embedded in the carbon matrix; Raman spectroscopy shows that the material has characteristic peaks (such as D peak and G peak) in a specific wavenumber range, indicating a high degree of graphitization of the carbon matrix.

[0024] In the embodiments of this application, the particle size of the SiOx particles is 0.5-2μm, for example, but not limited to at least one of 0.5μm, 1μm, 1.5μm or 2μm or any two of the numerical ranges; the porosity of the carbon fiber matrix is ​​60-80%, for example, but not limited to at least one of 60%, 65%, 70%, 75% or 80% or any two of the numerical ranges.

[0025] In an optional embodiment, the material has an initial discharge capacity ≥1400mAh / g and an initial coulombic efficiency ≥80%.

[0026] In an optional embodiment, the material further includes single-walled carbon nanotubes (SWCNTs) additives to increase the conductivity of the composite electrode material, wherein the amount added is 0.1%-2% of the total mass, for example, but not limited to at least one of 0.1%, 0.5%, 1%, 1.5% or 2% or any range of two of these values.

[0027] Secondly, the present invention provides a method for preparing a pre-lithiated SiOx composite electrode material, such as... Figure 1 As shown, it includes the following steps: S1. Silicon oxide precursor, copper-based carbonate and carbon fiber are wet-milled in an organic solvent under an inert atmosphere and dried to obtain pretreated powder.

[0028] Specifically, a certain amount of silicon oxide precursor is mixed with medium and large grinding balls, an organic solvent is added under an inert atmosphere, and the mixture is ball-milled and dried to obtain a pretreated powder.

[0029] In some preferred embodiments, the amount of carbon fiber added is 20%-30% of the mass of the silicon oxide precursor, for example, but not limited to at least one of 20%, 25% or 30% or any range of two of them, preferably 20%.

[0030] In some preferred embodiments, the ratio of the silicon oxide precursor to the copper-based carbonate is preferably 1:1.

[0031] And / or, the ball milling time is 6-12 hours, preferably 8-12 hours, and the ball-to-material ratio is in the range of (10-20):1.

[0032] S2. The metal salt and fibrous template material are mixed in a lithium hydroxide solution to form a uniform dispersion.

[0033] In this application embodiment, the metal salt includes, but is not limited to, iron salt, aluminum salt, copper salt or nickel salt, and the amount of metal salt added is 1-5% of the mass of the fibrous template material, for example, but not limited to at least one of 1%, 2%, 3%, 4% or 5% or any numerical range consisting of two of them. And / or, the fibrous template material includes, but is not limited to, cotton fibers, chitosan, alginate or PVA, and the concentration of its dispersion is controlled at 1:10-1:40 g / mL, for example, but not limited to at least one of 1:10, 1:20, 1:30 or 1:40 or any two of the numerical ranges.

[0034] S3. Disperse the pretreated powder in water, add a surfactant and stir to form a uniform suspension, then mix it with the dispersion, add it dropwise to an alcohol solvent and let it stand to form a precursor precipitate.

[0035] In some preferred embodiments, the alcohol solution is preferably an ethanol solution.

[0036] In some preferred embodiments, the surfactant includes, but is not limited to, the use of polyvinylpyrrolidone (PVP).

[0037] S4. The precipitate is mixed with the fast ion conductive coating material, and after acid treatment and drying, it is carbonized at high temperature under a protective atmosphere to obtain the pre-lithiated SiOx composite electrode material.

[0038] In some preferred embodiments, the fast ion conductor coating material is Al2O3 or M33 type conductive agent, which forms a surface alkaline neutralization and protective layer during the carbonization process.

[0039] Specifically, when the fast ion conductor coating material is Al2O3, its addition amount is 0.5%-5% of the total mass.

[0040] In an optional embodiment, the acid treatment uses hydrochloric acid for washing, the volume ratio of the hydrochloric acid solution is 1:(1-50), and the number of washing cycles is 1-3.

[0041] In an optional embodiment, the carbonization temperature is 700-900℃, and the heating rate is 2-5℃ / min.

[0042] Thirdly, the present invention provides a lithium-ion battery that uses the aforementioned pre-lithiated SiOx composite electrode material as the negative electrode active material.

[0043] In some preferred embodiments, the battery retains ≥85% of its capacity after 200 cycles at 1C rate.

[0044] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0045] Example 1 This embodiment provides a method for preparing a pre-lithiated SiOx composite electrode material, including the following steps: S1. Take 30-50 medium-sized grinding balls and 3-8 large-sized grinding balls, mix them with 2-3g of silicon oxide precursor, 2-3g of basic copper carbonate and 0.4-0.6g of carbon fiber, add 5-10mL of organic solvent, ball mill for 8-12 hours, dry and sieve to obtain pretreated powder (labeled as QM-SiOx).

[0046] S2. Dissolve the iron salt in lithium hydroxide solution, add 300-500 mg of cotton fiber, and stir for 20-40 minutes.

[0047] S3. Disperse 1.5-2.0g QM-SiOx in water, add 300-500mg PVP, stir and mix with the solution in S2, then add dropwise to the alcohol solvent and let stand for 12-24 hours.

[0048] S4, the precipitate is mixed with Al2O3, treated with acid, washed with water and dried, and then carbonized at 700-900℃ for 8-12 hours under a protective atmosphere to obtain the final material (marked as MH-22).

[0049] The surface morphology of the final material prepared in Example 1 was examined using electron microscopy, and the results are as follows: Figure 2As shown, SEM reveals that the material has a uniform porous structure with a pore size distribution of 0.5-2 μm.

[0050] Example 2 This embodiment provides a method for preparing a pre-lithiated SiOx composite electrode material. The steps are the same as those in Example 1, except that the amount of organic solvent in step S1 is 3-7 ml.

[0051] Comparative Example 1 This comparative example provides a method for preparing an electrode material, the steps of which include the following: taking 30-50 medium-sized grinding balls and 3-8 large-sized grinding balls, mixing them with 2-3g of silicon oxide precursor, 2-3g of basic copper carbonate and 0.4-0.6g of carbon fiber, adding 5-10mL of organic solvent, grinding for 8-12 hours, drying, and sieving to obtain electrode material powder.

[0052] Experimental Example 1 The pre-lithiated SiOx composite electrode material prepared in Example 1 and the electrode material prepared in Comparative Example 1 were subjected to rate performance testing, charge-discharge testing, Raman spectroscopy detection, cycle stability testing, and in-situ electrochemical impedance spectroscopy. The results are as follows: Figure 3-7 As shown.

[0053] Based on the above test results, it can be seen that, in terms of rate performance ( Figure 3 From the perspective of MH-22, it shows a significantly better specific capacity than QM-SiOx at all rates from 0.1C to 5C. Especially at high rates (such as 5C), MH-22 can still maintain a considerable discharge specific capacity, while the specific capacity of QM-SiOx drops sharply to close to 0. This indicates that MH-22 has better rate performance and fast charge and discharge capability.

[0054] From the initial charge and discharge efficiency ( Figure 4 From the perspective of the first charge and discharge cycle, the initial coulombic efficiency of MH-22 reaches 67.8%, which is higher than that of QM-SiOx (66.3%). This indicates that MH-22 has a higher utilization rate of active materials and relatively less irreversible capacity loss during the first charge and discharge cycle, which is of great significance for improving the overall energy density and cycle life of the battery.

[0055] Raman spectroscopy ( Figure 5 The results showed that MH-22 was at 1350 cm -1 and 1580 cm -1 The intensity of the nearby characteristic peaks is significantly higher than that of QM-SiOx, which corresponds to the D and G peaks of carbon materials. This indicates that the carbon layer in MH-22 is more graphitized, which is more conducive to electron transport and structural stability, thereby improving the electrochemical performance of the material.

[0056] Cyclic stability ( Figure 6 Tests show that, at a current density of 0.5C, after 250 cycles, the specific capacity retention of MH-22 is significantly higher than that of QM-SiOx, and MH-22 can stably maintain a specific capacity of approximately 1000 mAh g⁻¹. -1 The specific capacity of QM-SiOx rapidly decreases to approximately 500 mAh g⁻¹. -1 This indicates that the structure of MH-22 is more stable during cycling, which can effectively alleviate the volume expansion problem of silicon-based materials, thereby improving cycle life.

[0057] Electrochemical impedance spectroscopy (EIS) Figure 7 The results show that the charge transfer impedance and bulk impedance of MH-22 are significantly lower than those of QM-SiOx. This means that MH-22 has better electronic conductivity and ion transport capabilities, which can effectively reduce the internal resistance of the battery, improve electrochemical kinetic performance, and thus improve the rate performance and cycle stability of the battery.

[0058] In summary, the pre-lithiated SiOx composite electrode material (MH-22) prepared in this invention exhibits excellent comprehensive performance. In terms of electrochemical performance, the material achieves an initial discharge capacity exceeding 1500 mAh / g at 0.5C, and retains over 65% of its capacity after 100 cycles, demonstrating good capacity characteristics and cycle stability. Structural characterization reveals a uniform porous structure with pore sizes ranging from 0.5 to 2 μm. This porous structure effectively buffers the volume expansion of the silicon-based material during charge and discharge. Comparative experimental results show that compared to the uncomposite QM-SiOx material, MH-22 exhibits approximately 30% lower interfacial impedance, confirming that the cellulose-metal chelate coating effectively enhances interfacial bonding strength and reduces charge transfer resistance. Therefore, this material demonstrates high capacity and good stability in both lithium-ion battery anodes and electrocatalytic hydrogen evolution reactions, showing broad application prospects.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A pre-lithiated SiOx composite electrode material, characterized in that, The material includes: a carbon fiber matrix, SiOx particles uniformly dispersed in the carbon fiber matrix, and a cellulose-metal chelate coating layer covering the surface of the carbon fiber matrix.

2. The pre-lithiated SiOx composite electrode material according to claim 1, characterized in that, The SiOx particles have a particle size of 0.5-2 μm, and the carbon fiber matrix has a porosity of 60-80%.

3. The pre-lithiated SiOx composite electrode material according to claim 1, characterized in that, The material has an initial discharge capacity ≥1400mAh / g and an initial coulombic efficiency ≥80%.

4. The pre-lithiated SiOx composite electrode material according to claim 1, characterized in that, The material also includes single-walled carbon nanotube additives, with an addition amount of 0.1%-2% of the total mass.

5. A method for preparing a pre-lithiated SiOx composite electrode material as described in any one of claims 1-4, characterized in that, Includes the following steps: Silicon oxide precursor, copper-based carbonate and carbon fiber were wet-milled in an organic solvent under an inert atmosphere and dried to obtain a pretreated powder. The metal salt and fibrous template material were mixed in a lithium hydroxide solution to form a uniform dispersion. The pretreated powder was dispersed in water, a surfactant was added and stirred to form a uniform suspension, which was then mixed with the dispersion and added dropwise to an alcohol solvent and allowed to stand to form a precursor precipitate. The precipitate was mixed with a fast ion conductive coating material, and after acid treatment and drying, it was carbonized at high temperature under a protective atmosphere to obtain a pre-lithiated SiOx composite electrode material.

6. The method for preparing a pre-lithiated SiOx composite electrode material according to claim 5, characterized in that, The amount of carbon fiber added is 20%-30% of the mass of the silicon oxide precursor; And / or, the ball milling time is 6-12 hours, and the ball-to-material ratio is in the range of (10-20):

1.

7. The method for preparing a pre-lithiated SiOx composite electrode material according to claim 5, characterized in that, The metal salt is at least one selected from iron, aluminum, copper, or nickel salts, and the amount of the metal salt added is 1-5% of the mass of the fibrous template material. And / or, the fibrous template material is selected from at least one of cotton fiber, chitosan, alginate or PVA, and the concentration of its dispersion is controlled at 1:10-1:40 g / mL.

8. The method for preparing a pre-lithiated SiOx composite electrode material according to claim 5, characterized in that, The acid treatment uses hydrochloric acid for washing, the volume ratio of the hydrochloric acid solution is 1:(1-50), and the number of washing cycles is 1-3.

9. The method for preparing a pre-lithiated SiOx composite electrode material according to claim 5, characterized in that, The fast ion conductor coating material is Al2O3 or M33 type conductive agent; And / or, the carbonization temperature is 700-900℃, and the heating rate is 2-5℃ / min.

10. A lithium-ion battery, characterized in that, The battery contains the pre-lithiated SiOx composite electrode material as described in any one of claims 1-4 as the negative electrode active material, and the battery retains ≥85% of its capacity after 200 cycles at 1C rate.

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