Silicon-carbon negative electrode material for lithium battery prepared by electrostatic spinning method and preparation method of silicon-carbon negative electrode material
The preparation of silicon-carbon anode materials for lithium batteries by electrospinning and the formation of a continuous carbon shell structure by coating silicon particles with polymers solves the problems of complex preparation process and poor cycle stability in the existing technology, and achieves high efficiency in conductivity and improved cycle stability.
Patent Information
- Application Number
- CN202511020384.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-23
- Publication Date
- 2025-10-28
AI Technical Summary
The existing silicon-carbon anode materials for lithium batteries have complex preparation processes and poor cycle stability. Traditional methods are difficult to achieve uniform carbon coating and high conductivity.
Silicon-carbon anode material for lithium batteries was prepared by electrospinning. The polymer was mixed with silicon powder as a carbon source by coaxial electrospinning technology to form a double-layer polymer-coated silicon fiber structure. After calcination, a continuous carbon shell coating structure was formed, in which silicon particles were uniformly embedded and a conductive network was formed.
The prepared silicon-carbon anode material for lithium batteries has high initial capacity, high initial coulombic efficiency, high rate performance and excellent cycle stability, and is suitable for new high-capacity and high-cycle-stability lithium battery anode materials.
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Figure CN120854530A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery anode material technology, specifically to an electrospinning method for preparing silicon-carbon anode materials for lithium batteries and the same preparation method. Background Technology
[0002] Lithium-ion batteries are widely used as energy storage devices in consumer electronics, power tools, and electric vehicles, and improving their performance urgently depends on the development of new electrode materials. Currently, the theoretical specific capacity of commonly used graphite anode materials is approximately 372 mAh / g, which cannot meet the demands for high capacity and long lifespan. In contrast, silicon materials have a theoretical specific capacity as high as 4200 mAh / g, more than 10 times that of graphite, exhibiting a significant capacity advantage. However, silicon anodes undergo volume expansion exceeding 300% during charge and discharge, leading to material structure cracking, electrode pulverization, and repeated formation and peeling of the SEI film during cycling, resulting in problems such as low initial efficiency and poor cycle life.
[0003] To alleviate the volume expansion problem of silicon anodes and improve their conductivity, existing technologies typically employ a silicon / carbon composite material strategy, coating or doping silicon nanoparticles into a carbon network to form a buffer structure and conductive pathways. For example, coated silicon-carbon composites can be prepared using chemical vapor deposition (CVD), sintering, or direct carbonization of carbon precursors. These methods can improve the contact and conductivity of silicon particles to some extent, but they have some shortcomings in practical applications: First, traditional carbon coating is often uneven, with silicon particles potentially exposed or agglomerated locally, making it difficult to effectively prepare a continuous and uniform carbon coating; second, some methods are complex and costly, hindering large-scale production; and third, in coating or mixing methods, the fusion of carbon and silicon sources is insufficient, resulting in limited conductivity and mechanical stability of the composite material, failing to significantly improve the electrode's cycle stability. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing silicon-carbon anode materials for lithium batteries by electrospinning, which solves the problems of complex preparation process and poor cycle stability of silicon-carbon anode materials for lithium batteries in the prior art.
[0005] The present invention also provides an electrospinning method for preparing silicon-carbon anode materials for lithium batteries, in order to solve the problem of poor cycle stability of silicon-carbon anode materials for lithium batteries in the prior art.
[0006] To address the aforementioned problems, this invention proposes a method for preparing silicon-carbon anode materials for lithium batteries using electrospinning. The technical solution employed is as follows: A method for preparing silicon-carbon anode materials for lithium batteries by electrospinning includes the following steps: A double-layer polymer-coated silicon fiber structure is prepared by electrospinning an outer spinning solution containing a polymer and an inner spinning solution containing a mixture of silicon powder and polymer. The double-layer polymer-coated silicon fiber structure is then calcined to obtain a carbon-coated silicon anode material for lithium batteries.
[0007] The present invention has the following beneficial effects: The electrospinning method of this invention for preparing silicon-carbon anode materials for lithium batteries uses an outer spinning solution containing a polymer as the shell layer of coaxial spinning and an inner spinning solution containing a mixture of silicon powder and polymer as the core layer. Through coaxial electrospinning technology, silicon particles are effectively embedded into the core of a double-layer polymer fiber structure. The fiber surface forms a continuous and dense carbon shell from carbon precursors such as polymers, which facilitates uniform coating of silicon particles and buffers their volume expansion, thus obtaining a double-layer polymer-coated silicon fiber structure. This double-layer polymer-coated silicon fiber structure is then carbonized at high temperature to form a continuous carbon shell coating structure, allowing silicon particles to be uniformly embedded inside the fiber and forming a continuous conductive network. This significantly improves the overall conductivity of the silicon-carbon anode material for lithium batteries and effectively enhances the electrode's conductivity.
[0008] Compared to traditional powder mixing and single-liquid spinning processes, the electrospinning method of this invention for preparing silicon-carbon anode materials for lithium batteries produces more uniform carbon-coated silicon anode materials, avoiding incomplete carbon coatings and silicon particle agglomeration. The preparation process of this invention is simple and easy to implement, using readily available raw materials. The fiber structure and performance can be flexibly controlled by adjusting the spinning solution formulation and process parameters. The obtained silicon-carbon anode material exhibits high initial capacity, high initial coulombic efficiency, high rate performance, and excellent cycle stability, making it suitable for preparing novel high-capacity, high-cycle-stability lithium battery anode materials.
[0009] In order to enable the polymer to form a continuous and dense carbon shell as a carbon source, and to prevent insufficient fusion between the carbon source and the silicon source, thereby improving the uniformity of the polymer coating on the silicon particles and buffering their volume expansion, preferably, the polymer is selected from one of polylactic acid, polycaprolactone, lignin, pitch, glucose, polyacrylonitrile, polycarbonate, polyethylene terephthalate, polyglycolic acid, and polyvinylpyrrolidone.
[0010] To improve the uniformity of the fiber structure of the bilayer polymer-coated silicon, preferably, the solvents of the outer and inner spinning solutions are selected from one of dichloromethane, trichloromethane, hexafluoroisopropanol, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, and ethanol.
[0011] In order to enable the nano-silicon particles to be effectively embedded in the core of the fiber structure of the double polymer-coated silicon, preferably, the mass fraction of silicon powder in the inner spinning solution is 1~10 wt%, and the particle size of the silicon powder is 50~500 nm.
[0012] In order to enable the inner layer spinning solution containing a mixture of silicon powder and polymer to form an inner polymer coating layer around the nano-silicon particles after the electrospinning process, preferably, the mass fraction of the polymer in the inner layer spinning solution is 8~12wt%.
[0013] In order to form an outer polymer coating layer around the nano-silicon particles and the inner polymer coating layer after the electrospinning process, the outer spinning solution containing polymers preferably has a polymer mass fraction of 5-20 wt%.
[0014] In order to further and effectively embed silicon particles into the core of the fiber structure of the double polymer-coated silicon and promote the formation of a continuous and dense carbon shell from the carbon precursor of the polymer, preferably, the parameters of the electrospinning process are: spinning voltage: 15~30 kV, receiving distance: 10~25 cm, ambient temperature: 20~35℃, ambient humidity: 30~60% RH.
[0015] In order to promote the formation of a continuous conductive network in the fiber structure of double polymer-coated silicon and further improve the overall conductivity of silicon-carbon anode material for lithium batteries, preferably, the calcination treatment is carried out at a temperature of 600~1200℃ for 1~5 h in an inert gas or vacuum environment.
[0016] To further improve the overall conductivity of silicon-carbon anode materials for lithium batteries, preferably, the silicon content in the carbon-coated silicon anode material for lithium batteries is 5~50 wt%, and the carbon content is 50~95 wt%.
[0017] This invention also proposes an electrospinning method for preparing silicon-carbon anode materials for lithium batteries. The technical solution adopted is as follows: A method for preparing silicon-carbon anode materials for lithium batteries by electrospinning is disclosed, which is prepared by the above-mentioned method for preparing silicon-carbon anode materials for lithium batteries by electrospinning.
[0018] The beneficial effects of the present invention are: the preparation method of the present invention for preparing silicon-carbon anode material for lithium batteries by electrospinning has high initial capacity, high initial coulombic efficiency, high rate performance and excellent cycle stability and other electrochemical properties. Attached Figure Description
[0019] Figure 1 This is a battery rate diagram of the silicon-carbon anode material for lithium batteries in Example 4 of the present invention.
[0020] Figure 2 This is a battery rate diagram of the silicon-carbon anode material of Comparative Example 1 of the present invention.
[0021] Figure 3 This is a microscope image of the fiber structure of the double-layer polymer-coated silicon obtained during the preparation of the silicon-carbon anode material for lithium batteries in Example 4 of the present invention.
[0022] Figure 4 This is an electron microscope image of the silicon-carbon anode material for lithium batteries according to Example 4 of the present invention.
[0023] Figure 5 This is an electron microscope image of the silicon-carbon anode material of Comparative Example 1 of the present invention. Detailed Implementation
[0024] Existing technologies for preparing silicon-carbon anode materials for lithium-ion batteries involve complex processes and produce materials with poor cycle stability. This invention proposes a method for preparing silicon-carbon anode materials for lithium-ion batteries using electrospinning, comprising the following steps: A double-layer polymer-coated silicon fiber structure is prepared by electrospinning an outer spinning solution containing a polymer and an inner spinning solution containing a mixture of silicon powder and polymer. The double-layer polymer-coated silicon fiber structure is then calcined to obtain a carbon-coated silicon anode material for lithium batteries.
[0025] The technical concept of this invention is as follows: First, a polymer is used as a carbon source. The outer spinning solution containing the polymer can form the outermost polymer coating layer through electrospinning. The inner spinning solution containing a mixture of silicon powder and polymer can form a core structure through electrospinning. The core of the core structure is a silicon particle, and the outer layer of the core structure is an inner polymer coating layer on the outside of the silicon particle. This results in a double-layer polymer-coated silicon fiber structure with a structure of silicon particles, an inner polymer coating layer, and an outer polymer coating layer from the inside out. Then, the double-layer polymer-coated silicon fiber structure is calcined, so that the inner polymer coating layer and the inner polymer coating layer form a continuous carbon shell coating structure after high-temperature carbonization. This allows the silicon particles to be uniformly embedded inside the fiber and form a continuous conductive network, which can significantly improve the overall conductivity of the silicon-carbon anode material for lithium batteries and effectively improve the conductivity of the electrode.
[0026] Compared to traditional powder mixing and single-liquid spinning processes, the electrospinning method of this invention for preparing silicon-carbon anode materials for lithium batteries produces more uniform carbon-coated silicon anode materials, avoiding incomplete carbon coatings and silicon particle agglomeration. The preparation process of this invention is simple and easy to implement, using readily available raw materials. The fiber structure and performance can be flexibly controlled by adjusting the spinning solution formulation and process parameters. The obtained silicon-carbon anode material exhibits high initial capacity, high initial coulombic efficiency, high rate performance, and excellent cycle stability, making it suitable for preparing novel high-capacity, high-cycle-stability lithium battery anode materials.
[0027] Specifically, the preparation method of silicon-carbon anode material for lithium batteries by electrospinning includes the following steps: (1) Preparation of inner spinning solution: A mixture of nano-silica powder and polymer is added to the solvent of the inner spinning solution to obtain the inner spinning solution; wherein, the mass fraction of silica powder in the inner spinning solution is 1~10 wt%, and the particle size of silica powder is 50~500 nm; the mass fraction of polymer in the inner spinning solution is 8~12 wt%; (2) Preparation of outer spinning solution: The polymer is added to the solvent of the outer spinning solution to obtain the outer spinning solution; wherein the mass fraction of the polymer in the outer spinning solution is 5~20wt%; (3) Electrospinning process: The inner spinning solution and the outer spinning solution are respectively loaded into the inner and outer syringes of the coaxial electrospinning device, and electrospinning is carried out simultaneously through the coaxial spinneret. The parameters of the electrospinning process are: spinning voltage: 15~30 kV, receiving distance: 10~25 cm, ambient temperature: 20~35℃, ambient humidity: 30~60% RH, inner layer flow rate: 0.5 mL / h, outer layer flow rate: 1.0 mL / h, and a rotating metal roller with a collection speed of 1000~2000 rpm is used to collect the double-layer polymer-coated silicon fiber structure. (4) Calcination treatment: The obtained double-layer polymer-coated silicon fiber structure is carbonized at a temperature of 600~1200℃ for 1~5 h under inert gas or vacuum protection to obtain carbon-coated silicon anode material for lithium batteries.
[0028] Specifically, the polymer is selected from one of polylactic acid, polycaprolactone, lignin, asphalt, glucose, polyacrylonitrile, polycarbonate, polyethylene terephthalate, polyglycolic acid, and polyvinylpyrrolidone.
[0029] The solvents for the outer spinning solution and the inner spinning solution are selected from one of dichloromethane, trichloromethane, hexafluoroisopropanol, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, and ethanol.
[0030] The implementation process of the present invention will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. It should also be noted that, for ease of description, only the parts related to the invention are shown in the embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the embodiments. It should be noted that the endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0031] In the following examples and comparative examples, the silicon powder used had a particle size of 50-500 nm, and the rest were ordinary commercially available products that could be directly purchased or prepared using conventional techniques in the field.
[0032] I. Examples of the preparation method of silicon-carbon anode material for lithium batteries by electrospinning according to the present invention Example 1 The method for preparing silicon-carbon anode materials for lithium batteries by electrospinning provided in this embodiment includes the following steps: (1) Preparation of the internal spinning solution: A mixture of nano-silica powder and polyvinylpyrrolidone is added to N,N- In a dimethylformamide solution, the particles were uniformly dispersed under magnetic stirring to obtain an inner layer spinning solution; wherein the inner layer spinning solution contained 5 wt% nano-silica powder and 10 wt% polyvinylpyrrolidone. (2) Preparation of outer spinning solution: Polyacrylonitrile is added to N,N-dimethylformamide solution to obtain outer spinning solution; wherein, the mass fraction of polyacrylonitrile in the outer spinning solution is 12 wt%; (3) Electrospinning process: The inner spinning solution and the outer spinning solution are respectively loaded into the inner and outer syringes of the coaxial electrospinning device, and electrospinning is carried out simultaneously through the coaxial spinneret. The parameters of the electrospinning process are: spinning voltage: 15 kV, receiving distance: 15 cm, ambient temperature: 25℃, ambient humidity: 30% RH, inner layer flow rate: 0.5 mL / h, outer layer flow rate: 1.0 mL / h, and the polymer-coated silicon fiber structure is collected using a rotating metal roller with a collection speed of 1000 rpm. (4) Calcination treatment: The obtained polymer-coated silicon fiber structure is carbonized at 700℃ for 3h under nitrogen protection to obtain carbon-coated silicon anode material for lithium batteries.
[0033] Example 2 The method for preparing silicon-carbon anode materials for lithium batteries by electrospinning provided in this embodiment includes the following steps: (1) Preparation of inner spinning solution: The mixture of nano-silica powder and polycaprolactone was added to N,N-dimethylformamide solution and dispersed evenly under ultrasonic oscillation to obtain inner spinning solution; wherein, the mass fraction of nano-silica powder in inner spinning solution is 10 wt% and the mass fraction of polycaprolactone in inner spinning solution is 12 wt%; (2) Preparation of outer spinning solution: Pitch is added to N,N-dimethylformamide solution to obtain outer spinning solution; wherein, the mass fraction of pitch in outer spinning solution is 10 wt%; (3) Electrospinning process: The inner layer spinning solution and the outer layer spinning solution are respectively loaded into the inner and outer syringes of the coaxial electrospinning device, and electrospinning is carried out simultaneously through the coaxial spinneret. The parameters of the electrospinning process are: spinning voltage: 18 kV, receiving distance: 15 cm, ambient temperature: 25℃, ambient humidity: 30% RH, inner layer flow rate: 0.5 mL / h, outer layer flow rate: 1.0 mL / h, and the polymer-coated silicon fiber structure is collected using a rotating metal roller with a collection speed of 1000 rpm. (4) Calcination treatment: The obtained polymer-coated silicon fiber structure is carbonized at 800℃ for 3h under nitrogen protection to obtain carbon-coated silicon anode material for lithium batteries.
[0034] Example 3 The method for preparing silicon-carbon anode materials for lithium batteries by electrospinning provided in this embodiment includes the following steps: (1) Preparation of inner spinning solution: The mixture of nano-silica powder and polylactic acid is added to N,N-dimethylformamide solution and dispersed evenly under ultrasonic oscillation to obtain inner spinning solution; wherein, the mass fraction of nano-silica powder in inner spinning solution is 1 wt% and the mass fraction of polylactic acid in inner spinning solution is 8 wt%; (2) Preparation of outer spinning solution: Polycaprolactone was added to N,N-dimethylformamide solution to obtain outer spinning solution; wherein, the mass fraction of polycaprolactone in the outer spinning solution was 18 wt%; (3) Electrospinning process: The inner spinning solution and the outer spinning solution are respectively loaded into the inner and outer syringes of the coaxial electrospinning device, and electrospinning is carried out simultaneously through the coaxial spinneret. The parameters of the electrospinning process are: spinning voltage: 25 kV, receiving distance: 20 cm, ambient temperature: 25℃, ambient humidity: 30% RH, inner layer flow rate: 0.5 mL / h, outer layer flow rate: 1.0 mL / h, and the polymer-coated silicon fiber structure is collected using a rotating metal roller with a collection speed of 2000 rpm. (4) Calcination treatment: The obtained polymer-coated silicon fiber structure is carbonized at 1200℃ for 1h under nitrogen protection to obtain carbon-coated silicon anode material for lithium batteries.
[0035] Example 4 The method for preparing silicon-carbon anode materials for lithium batteries by electrospinning provided in this embodiment includes the following steps: (1) Preparation of inner spinning solution: The mixture of nano-silica powder and pitch is added to N,N-dimethylformamide solution and dispersed evenly under ultrasonic oscillation to obtain inner spinning solution; wherein, the mass fraction of nano-silica powder in inner spinning solution is 10wt% and the mass fraction of pitch in inner spinning solution is 10wt%; (2) Preparation of outer spinning solution: Polyvinylpyrrolidone was added to N,N-dimethylformamide solution to obtain outer spinning solution; wherein, the mass fraction of polyvinylpyrrolidone in the outer spinning solution was 18 wt%; (3) Electrospinning process: The inner spinning solution and the outer spinning solution are respectively loaded into the inner and outer syringes of the coaxial electrospinning device, and electrospinning is carried out simultaneously through the coaxial spinneret. The parameters of the electrospinning process are: spinning voltage: 25 kV, receiving distance: 20 cm, ambient temperature: 25℃, ambient humidity: 30% RH, inner layer flow rate: 0.5 mL / h, outer layer flow rate: 1.0 mL / h, and the polymer-coated silicon fiber structure is collected using a rotating metal roller with a collection speed of 2000 rpm. (4) Calcination treatment: The obtained polymer-coated silicon fiber structure is carbonized at 800℃ for 3h under nitrogen protection to obtain carbon-coated silicon anode material for lithium batteries.
[0036] Example 5 The method for preparing silicon-carbon anode materials for lithium batteries by electrospinning provided in this embodiment includes the following steps: (1) Preparation of internal spinning solution: Add a mixture of nano-silica powder and polylactic acid to hexafluoroisopropanol. The solution is uniformly dispersed under ultrasonic oscillation to obtain an inner layer spinning solution; wherein the mass fraction of nano-silica powder in the inner layer spinning solution is 5 wt%, and the mass fraction of polylactic acid in the inner layer spinning solution is 10 wt%. (2) Preparation of outer spinning solution: Polycarbonate is added to hexafluoroisopropanol solution to obtain outer spinning solution; wherein, the mass fraction of polycarbonate in outer spinning solution is 18 wt%; (3) Electrospinning process: The inner spinning solution and the outer spinning solution are respectively loaded into the inner and outer syringes of the coaxial electrospinning device, and electrospinning is carried out simultaneously through the coaxial spinneret. The parameters of the electrospinning process are: spinning voltage: 25 kV, receiving distance: 10 cm, ambient temperature: 30℃, ambient humidity: 30% RH, inner layer flow rate: 0.5 mL / h, outer layer flow rate: 1.0 mL / h, and the polymer-coated silicon fiber structure is collected using a rotating metal roller with a collection speed of 2000 rpm. (4) Calcination treatment: The obtained polymer-coated silicon fiber structure is carbonized at 600℃ for 5h under nitrogen protection to obtain carbon-coated silicon anode material for lithium batteries.
[0037] Example 6 The method for preparing silicon-carbon anode materials for lithium batteries by electrospinning provided in this embodiment includes the following steps: (1) Preparation of inner spinning solution: The mixture of nano-silica powder and lignin is added to N,N-dimethylformamide solution and dispersed evenly under ultrasonic oscillation to obtain inner spinning solution; wherein, the mass fraction of nano-silica powder in inner spinning solution is 5wt% and the mass fraction of lignin in inner spinning solution is 10wt%; (2) Preparation of outer spinning solution: Polycaprolactone is added to N,N-dimethylformamide solution to obtain outer spinning solution; wherein, the mass fraction of polycaprolactone in outer spinning solution is 5 wt%; (3) Electrospinning process: The inner spinning solution and the outer spinning solution are respectively loaded into the inner and outer syringes of the coaxial electrospinning device, and electrospinning is carried out simultaneously through the coaxial spinneret. The parameters of the electrospinning process are: spinning voltage: 20kV, receiving distance: 20 cm, ambient temperature: 30℃, ambient humidity: 45% RH, inner layer flow rate: 0.5 mL / h, outer layer flow rate: 1.0 mL / h, and the polymer-coated silicon fiber structure is collected using a rotating metal roller with a collection speed of 1500 rpm. (4) Calcination treatment: The obtained polymer-coated silicon fiber structure is carbonized at 700℃ for 2 hours under nitrogen protection to obtain carbon-coated silicon anode material for lithium batteries.
[0038] In this application, when the polymer is selected from glucose, polyethylene terephthalate, and polyglycolic acid, the effect obtained is the same as that obtained in the above embodiments.
[0039] In this application, when the solvents for the outer spinning solution and the inner spinning solution are selected from one of dichloromethane, trichloromethane, dimethyl sulfoxide, tetrahydrofuran, and ethanol, the effect obtained is the same as that obtained in the above embodiments.
[0040] II. Comparative Example Comparative Example 1 The method for preparing the silicon-carbon anode material provided in this comparative example includes the following steps: (1) Material mixing: Nano silicon powder (particle size about 100nm), polyacrylonitrile and conductive carbon black are mixed in a weight ratio of 5:90:5, ultrasonically dispersed in N,N-dimethylformamide, and then stirred evenly at room temperature. After drying, silicon / polyacrylonitrile composite powder is obtained. (2) Heat treatment: The silicon / polyacrylonitrile composite powder was calcined at 800°C for 3 hours under a nitrogen atmosphere to obtain the carbonized silicon-carbon anode material.
[0041] Comparative Example 2 The method for preparing the silicon-carbon anode material provided in this comparative example includes the following steps: (1) Material mixing: Nano-silicon powder (particle size of about 100 nm) is uniformly dispersed in a polyacrylonitrile solution to obtain a solution containing silicon and polyacrylonitrile, wherein the mass fraction of polyacrylonitrile in the solution containing silicon and polyacrylonitrile is 12 wt%; (2) Electrospinning process: Single liquid electrospinning process is adopted. The parameters of the electrospinning process are: spinning voltage: 20kV, receiving distance: 15 cm, flow rate: 1.0 mL / h, and a rotating metal drum with a collection speed of 1000 rpm is used to collect silicon-carbon anode material.
[0042] III. Experimental Examples Experimental Example 1: Electrochemical Performance The electrochemical performance of the silicon-carbon anode materials for lithium batteries prepared in Examples 1-6 and the silicon-carbon anode materials prepared in Comparative Examples 1 and 2 was tested.
[0043] Specifically, the preparation method of the coin cell used for testing electrochemical performance is as follows: Li metal was used as the counter electrode, and a 0.1C rate charge-discharge test was conducted. The silicon-carbon anode materials for lithium batteries prepared in Examples 1-6 and the silicon-carbon anode materials prepared in Comparative Examples 1 and 2 were used as the battery anode materials. These were mixed with CMC, SBR, and a conductive agent (super P) in a ratio of 80:5:5:10 and uniformly coated onto copper foil. After vacuum drying, this mixture served as the anode. Lithium metal was used as the counter electrode. The electrolyte was a 1M LiPF6 mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 mass ratio. The separator was a PE / PP / PE composite membrane. A CR2032 coin cell was assembled. The test conditions were: electrochemical performance was measured at a current density of 0.1C. The results are shown in Tables 1 and 2. Table 1. Electrochemical performance test results of the silicon-carbon anode materials for lithium batteries prepared in Examples 1-6
[0044] Table 2. Electrochemical performance test results of silicon-carbon anode materials prepared in Comparative Examples 1-2
[0045] As shown in Tables 1 and 2, the silicon-carbon anode materials for lithium batteries prepared in Examples 1-6, when tested at a current density of 0.1C, exhibit an initial reversible capacity of over 1300 mAh / g, with a maximum of 1800 mAh / g; and an initial coulombic efficiency of over 75%, with a maximum of 82%. After 100 cycles, the capacity retention is over 68%, with a maximum of 75%. This indicates that the silicon-carbon anode materials for lithium batteries prepared in this application improve conductivity and initial coulombic efficiency, and possess good cycle stability.
[0046] In Comparative Example 1, the capacity retention of the silicon-carbon anode material after 100 charge-discharge cycles was only 1%, far lower than the performance of the silicon-carbon anode materials for lithium batteries in Examples 1-6. This indicates that the silicon-carbon anode material prepared by the physical mixing method in Comparative Example 1 has an inhomogeneous structure and poor mechanical stability. In Comparative Example 2, the initial coulombic efficiency of the silicon-carbon anode material was low, and the capacity retention after 100 charge-discharge cycles was only 60%, indicating poor cycle performance and unstable electrochemical behavior. This suggests that the carbon-coated structure prepared by single-liquid spinning has defects.
[0047] Experimental Example 2: Rate Performance The electrochemical rate performance of the lithium-ion battery silicon-carbon anode materials prepared in Examples 1-6 and the silicon-carbon anode materials prepared in Comparative Examples 1 and 2 was tested under current densities of 0.2C, 0.5C, and 1C. The results are shown in Table 3. Simultaneously, the rate performance of the lithium-ion battery silicon-carbon anode material prepared in Example 4 and the silicon-carbon anode material prepared in Comparative Example 1 was tested, with a charge-discharge rate of 0.1C and a charging voltage limited to 0.01~2 V. The results are shown in Table 3. Figure 1 and Figure 2 shown.
[0048] Table 3. Electrochemical rate performance test results of silicon-carbon anode materials prepared in Examples 1-6 and Comparative Examples 1-2.
[0049] From Table 3 and Figure 1 , Figure 2 It can be seen that the silicon-carbon anode materials for lithium batteries prepared in Examples 1-6 have an electrochemical rate of over 1320 at a current density of 0.2C, an electrochemical rate of over 1070 at a current density of 0.5C, and an electrochemical rate of over 550 at a current density of 1C. In contrast, in Comparative Examples 1 and 2, the silicon-carbon anode materials have an electrochemical rate of 100 at a current density of 0.2C, an electrochemical rate of less than 50 at a current density of 0.5C, and an electrochemical rate of less than 30 at a current density of 1C. This indicates that the electrochemical rate performance of the silicon-carbon anode materials for lithium batteries prepared in this application is much higher than that of Comparative Examples 1 and 2, demonstrating superior electrochemical rate performance.
[0050] Experiment Example 3: Appearance Inspection The polymer-coated silicon fiber structure obtained during the preparation of the silicon-carbon anode material for lithium batteries in Example 4 above was examined under a microscope. The results are as follows: Figure 3 As shown, it can be concluded that the fiber structure of double-layer polymer-coated silicon forms a core-shell structure, which provides a structural basis for the carbon-coated silicon for lithium batteries formed by calcination.
[0051] The silicon-carbon anode material for lithium batteries prepared in Example 4 and the silicon-carbon anode material prepared in Comparative Example 1 were examined using transmission electron microscopy. The results are as follows: Figure 4 and Figure 5 As shown, it can be concluded that the silicon-carbon anode material for lithium batteries prepared in Example 4 and the silicon-carbon anode material prepared in Comparative Example 1 were both subjected to calcination treatment. The silicon-carbon anode material after calcination treatment exhibits a layered structure, which greatly improves the rate performance and cycle performance of silicon.
[0052] This demonstrates that the electrospinning method of the present invention for preparing silicon-carbon anode materials for lithium batteries produces silicon-carbon anode materials with excellent charge-discharge performance, rate performance, and cycle stability, resulting in good cycle life. This significantly improves the energy density, cycle life, and safety of silicon-carbon anode materials, providing a new solution for the development of lithium-ion battery technology.
[0053] 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 method for preparing silicon-carbon anode materials for lithium batteries by electrospinning, characterized in that, The following steps are involved: A double-layer polymer-coated silicon fiber structure is prepared by electrospinning an outer spinning solution containing a polymer and an inner spinning solution containing a mixture of silicon powder and polymer. The double-layer polymer-coated silicon fiber structure is then calcined to obtain a carbon-coated silicon anode material for lithium batteries.
2. The method for preparing silicon-carbon anode material for lithium batteries by electrospinning according to claim 1, characterized in that, The polymer is selected from one of polylactic acid, polycaprolactone, lignin, asphalt, glucose, polyacrylonitrile, polycarbonate, polyethylene terephthalate, polyglycolic acid, and polyvinylpyrrolidone.
3. The method for preparing silicon-carbon anode material for lithium batteries by electrospinning according to claim 1, characterized in that, The solvents for the outer and inner spinning solutions are selected from one of dichloromethane, trichloromethane, hexafluoroisopropanol, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, and ethanol.
4. The method for preparing silicon-carbon anode material for lithium batteries by electrospinning according to claim 1, characterized in that, The inner spinning solution contains 1-10 wt% silicon powder with a particle size of 50-500 nm.
5. The method for preparing silicon-carbon anode material for lithium batteries by electrospinning according to claim 1, characterized in that, The mass fraction of the polymer in the inner spinning solution is 8-12 wt%.
6. The method for preparing silicon-carbon anode material for lithium batteries by electrospinning according to claim 1, characterized in that, The mass fraction of the polymer in the outer spinning solution is 5-20 wt%.
7. The method for preparing silicon-carbon anode material for lithium batteries by electrospinning according to claim 1, characterized in that, The parameters of the electrospinning process are as follows: spinning voltage: 15~30 kV, receiving distance: 10~25 cm, ambient temperature: 20~35℃, ambient humidity: 30~60% RH.
8. The method for preparing silicon-carbon anode material for lithium batteries by electrospinning according to claim 1, characterized in that, The calcination treatment is carried out at a temperature of 600~1200℃ for 1~5 hours in an inert gas or vacuum environment.
9. The method for preparing silicon-carbon anode material for lithium batteries by electrospinning according to claim 1, characterized in that, The silicon content in the carbon-coated silicon anode material for lithium batteries is 5-50 wt%, and the carbon content is 50-95 wt%.
10. A method for preparing silicon-carbon anode materials for lithium batteries by electrospinning, characterized in that, It is prepared by the method for preparing silicon-carbon anode material for lithium batteries by electrospinning as described in any one of claims 1 to 9.