A double-layer nanometer silicon-based material, a preparation method and application thereof

Abstract

The application discloses a double-layer nanometer silicon-based material and a preparation method and application thereof, and belongs to the technical field of energy storage. The double-layer nanometer silicon-based material comprises, from inside to outside, a core layer, a first shell layer and a second shell layer; the core layer is nanometer silicon, the first shell layer is a silicon carbide layer with a thickness of 1.1-5.0 nm, and the second shell layer is a carbon layer with a thickness of 1.1-4.2 nm; a carbon-silicon bond is formed between the core layer and the first shell layer, and a carbon-silicon bond is formed between the first shell layer and the second shell layer. The material is physically limited in volume expansion of silicon through a high-strength rigid skeleton on one hand, and constructs a functional interface layer for ion / electron cooperative conduction on the other hand, so that unification of stress buffering, interface stability and rapid kinetics is realized.

Description

TECHNICAL FIELD

[0001] The application relates to a double-layer nanosilicon-based material and a preparation method and application thereof, and belongs to the technical field of energy storage. BACKGROUND

[0002] High-energy-density and high-safety solid-state batteries have become an inevitable trend of development of power batteries and energy storage technologies. Compared with traditional liquid lithium batteries, the solid-state battery adopts a non-flammable solid-state electrolyte, fundamentally inhibits the risk of thermal runaway, and is compatible with high-voltage anodes and high-capacity cathodes, thereby providing a technical path for breaking through the energy density of 500 Wh / kg.

[0003] Silicon-carbon anode materials are considered as a core anode system for realizing the leap of battery energy density because of the theoretical specific capacity of up to 3580 mAh / g, far exceeding that of graphite anodes (372 mAh / g). However, the volume expansion of silicon during lithiation exceeds 300%, leading to particle breakage, electrode structure collapse and repeated reconstruction of the solid electrolyte interface (SEI), thereby causing key problems such as short cycle life and low coulombic efficiency. Under the stringent requirements of interface contact and mechanical stability of solid-state batteries, the traditional silicon-carbon composite material is difficult to meet the long-term service requirement.

[0004] In order to solve the technical scheme in the prior art, there are silicon carbide-coated silicon-based anode materials, such as patent CN119725454A. Although this method can inhibit the volume expansion of silicon during lithiation to a certain extent, the silicon carbide layer reduces the ion transmissivity and conductivity of the silicon-based material. There are also carbon-coated silicon-based materials, such as patent CN115425222A. In this way, the carbon layer on the surface of the silicon-based material is extremely unstable and will automatically fall off with the reaction, and the effect of reducing the volume expansion rate is limited. There are also double-layer composite materials coated on the surface of the silicon-based material, such as patent CN107994217A. The graphene layer is grown on the surface of the C@ nanosilicon-based material by catalytic growth, and then carbon coating is performed. The anode material with good stability can be obtained to a certain extent. However, the catalyst is used in this way, and it is difficult to clean the catalyst out in the subsequent process, thereby reducing the relative active component, so that the theoretical capacity of the silicon-based material cannot be fully utilized, and the highest specific capacity is only 1202.1 mAh / g. SUMMARY

[0005] In order to solve the above problems, a double-layer nanosilicon-based material is provided. On the one hand, the volume expansion of silicon is physically confined by a high-strength rigid skeleton; on the other hand, a functional interface layer for the coordinated conduction of ions and electrons is constructed, so as to realize the unification of stress buffering, interface stability and rapid kinetics.

[0006] According to a first aspect of the present application, a double-layer nanosilicon-based material is provided, which comprises a core layer and first and second shell layers in sequence from inside to outside;

[0007] The core layer is nanosilicon, the first shell layer is a silicon carbide layer with a thickness of 1.1-5.0 nm, and the second shell layer is a carbon layer with a thickness of 1.1-4.2 nm;

[0008] Carbon-silicon bonds are formed between the core layer and the first shell layer, and carbon-silicon bonds are formed between the first shell layer and the second shell layer.

[0009] The double-layer nanosilicon-based material can limit the volume expansion of silicon by the sequential coating of the silicon carbide layer and the carbon layer, and the carbon layer can also be beneficial to ion conduction and electrical conductivity. The carbon-silicon bonds between the core layer and the first shell layer form a silicon-silicon carbide gap, and the carbon-silicon bonds between the first shell layer and the second shell layer form a silicon carbide-carbon gap. The existence of the two gaps provides a buffer space for the nanosilicon to inhibit the overall volume expansion of the double-layer nanosilicon-based material, so as to meet the long-term service requirement and improve the cycle life of the battery. The second shell layer formed is a carbon layer containing microporous and mesoporous structures, which can promote the coordinated conduction of ions and electrons, thereby improving the specific capacity and cycle performance.

[0010] Optionally, the particle size of the double-layer nanosilicon-based material is 20-210 nm, the specific surface area is 1-60.0 m 2 / g, the pore size is 0.8-3.0 nm, and the pore volume is 0.01-0.1 cm 3 / g.

[0011] Preferably, the specific surface area of the double-layer nanosilicon-based material is 8.1-51.0 m 2 / g, the pore size is 0.9-1.9 nm, and the pore volume is 0.01-0.06 cm 3 / g.

[0012] Optionally, the crystallinity of the second shell layer is 10%-90%, preferably 35-90%, and more preferably 35%-80%.

[0013] The crystallinity of the carbon layer is low, which can play a role in ion conduction and can enhance the electrical conductivity of the material compared to amorphous carbon.

[0014] According to a second aspect of the present application, a preparation method of a double-layer nanosilicon-based material is provided, which comprises the following steps:

[0015] (1) mixing silicon material and fluorinated organic matter in a weight ratio of 1: (0.3-15) in a solvent to obtain mixed slurry A, and then spray drying the mixed slurry A to obtain mixed material A;

[0016] (2) the mixture A is subjected to one-time high-temperature energy field treatment to obtain an intermediate of a first shell layer covering a core layer;

[0017] (3) the intermediate and fluorinated organic matter in a weight ratio of (0.5-10):1 are mixed in a solvent to obtain a mixed slurry B, and the mixed slurry B is spray dried to obtain a mixture B;

[0018] (4) the mixture B is subjected to two-time high-temperature energy field treatment to obtain a double-layer nano-silicon-based material of a second shell layer covering the intermediate.

[0019] The preparation method first adopts one-time high-temperature energy field treatment to form an intermediate of a first shell layer covering a core layer, and the one-time high-temperature energy field treatment can make the silicon and carbon atoms instantaneously form a silicon-carbon gap due to instantaneous heating and in-situ bonding shrinkage; then two-time high-temperature energy field treatment is adopted to obtain a double-layer nano-silicon-based material of a second shell layer covering the intermediate, and the two-time high-temperature energy field treatment can make the silicon atoms in the first shell layer and the carbon atoms in the second shell layer instantaneously form a silicon-carbon chemical bond, so that the interface between the first shell layer and the second shell layer shrinks to form a silicon carbide-carbon gap.

[0020] Therefore, the preparation method adopts two-time high-temperature energy field treatment to form a gap between the core layer and the first shell layer and between the first shell layer and the second shell layer, so as to provide a buffer space for the volume expansion of the nano-silicon and inhibit the volume expansion of the double-layer nano-silicon-based material. Compared with the silicon carbide layer or carbon layer formed by the traditional sintering process, the method changes the original physical combination into chemical bond combination, instantaneously forms a bond, and adjusts the silicon-carbon interaction force, so as to minimize the volume expansion of the double-layer nano-silicon material.

[0021] The fluorinated organic matter is used to form the first shell layer and the second shell layer, which can utilize the bond energy of the carbon-fluorine bond to generate a silicon-carbon bond in-situ under the two-time high-temperature energy field treatment, so as to form a gap between the core layer, the first shell layer and the second shell layer.

[0022] Optionally, the solvent is selected from one or more of pure water, ethanol, acetone, n-hexane, cyclohexane and methyl pyrrolidone.

[0023] Optionally, in step (1), the weight of the solvent is 2-8 times the total weight of the silicon material and the fluorinated organic matter, and in step (2), the weight of the solvent is 2-8 times the total weight of the intermediate and the organic matter.

[0024] Optionally, in step (2), the one-time high-temperature energy field treatment has a heating rate of 50-1500℃ / s, a treatment temperature of 550-1450℃ and a time of 0.2-4h; and / or

[0025] The heating rate of the secondary instantaneous high-temperature energy field in step (4) is 50-1500℃ / s, the processing temperature is 550-1200℃, and the time is 0.05-1h.

[0026] The above heating rate can ensure instantaneous heating, thereby ensuring that the silicon-carbon atoms are instantaneously heated to form a chemical bond in situ, which is conducive to the formation of the gap. The processing temperature of the secondary instantaneous high-temperature energy field is lower than that of the primary instantaneous high-temperature energy field, which can promote the formation of the carbon layer. If the processing temperature of the secondary instantaneous high-temperature energy field is too high, the silicon-carbon force will be enhanced, causing the silicon carbide layer and the carbon layer to become thicker. The above processing time can control the thickness and crystallinity of the carbon layer.

[0027] If the heating rate is lower than 50℃ / s, the silicon-carbon atoms cannot form a silicon-carbon chemical bond due to instantaneous heating, the core layer, the first shell layer, and the second shell layer are only physically combined, it is difficult to form a gap, and it is difficult to effectively inhibit the volume expansion of the material. If the heating rate is higher than 1500℃ / s, the silicon carbide layer forms too quickly, and it is difficult to control its thickness.

[0028] Optionally, the heating rate of the primary instantaneous high-temperature energy field and the secondary instantaneous high-temperature energy field is realized by one or more of Joule heating, plasma, flash technology, and alloy resistance wire heating.

[0029] Optionally, the atmosphere of the primary instantaneous high-temperature energy field and the secondary instantaneous high-temperature energy field includes one or more of Air, N2, Ar, and vacuum.

[0030] Optionally, the fluorinated organic matter is selected from at least one of fluorinated starch, fluorinated phenolic resin, fluorinated epoxy resin, and fluorine-containing plastic, and the molecular weight of the fluorinated organic matter is 50-1000 million.

[0031] The particle size of the fluorinated organic matter is 0.1-200 μm.

[0032] Optionally, the fluorine-containing plastic is selected from tetrafluoroethylene or vinylidene fluoride.

[0033] The above-mentioned types of fluorinated organic matter can ensure the formation of the first shell layer and the second shell layer, improve the thickness uniformity of the first shell layer and the second shell layer, and reduce production costs. The molecular weight of the fluorinated organic matter can help control the severity of the reaction. If the molecular weight is lower than 50 million, the reaction rate is extremely slow. If the molecular weight is higher than 1000 million, the reaction is too violent. The particle size can effectively control the uniformity of the shell layer. If the particle size is too low, the shell layer is too thin. If the particle size is too large, the shell layer is too thick.

[0034] Preferably, the molecular weight of the fluorinated organic matter is 100-500 million.

[0035] Optionally, the particle size of the silicon material in step (1) is 2-50 μm, preferably 15 μm.

[0036] The silicon material and the fluorinated organic material are prepared by the above preparation method to form a nanosilicon core layer, a first shell layer with a nanometer thickness, and a second shell layer, thereby obtaining a double-layer nanosilicon-based material with a particle size of 20-210 nm.

[0037] Optionally, the temperature for spray drying in step (1) and step (3) is 120-300 °C.

[0038] Optionally, the mixing time in step (1) and step (3) is 0.5-2 h.

[0039] Preferably, the mixing in step (1) and step (3) comprises one or more of stirring, ultrasonic, and microwave intensification.

[0040] According to a third aspect of the present application, a battery is provided, which comprises the double-layer nanosilicon-based material of any one of the above or the double-layer nanosilicon-based material prepared by the preparation method of any one of the above.

[0041] According to a fourth aspect of the present application, the double-layer nanosilicon-based material of any one of the above or the double-layer nanosilicon-based material prepared by the preparation method of any one of the above is applied in an energy storage device.

[0042] The benefits of the present application include but are not limited to:

[0043] 1. The double-layer nanosilicon-based material according to the present application, a carbon-silicon bond is formed between the first shell layer and the core layer, so that a silicon-silicon carbide gap is formed between the first shell layer and the core layer, a carbon-silicon bond is formed between the first shell layer and the second shell layer, so that a silicon carbide-carbon gap is formed between the first shell layer and the second shell layer, the above two gaps can act as a buffer space for nanosilicon, inhibiting the volume expansion of the material, and the dual action of the silicon carbide layer and the carbon layer can effectively inhibit the interface side reaction of silicon and electrolyte, enhance the rate performance and cycle stability, and have a wide application prospect.

[0044] 2. The double-layer nanosilicon-based material according to the present application, the nanosilicon is coated with a first shell layer of silicon carbide and a second shell layer of low-crystallinity carbon in sequence, which not only inhibits the volume expansion of the silicon-based material during charging and discharging, but also enhances the ion conductivity and electrical conductivity of the silicon-based material.

[0045] 3. The double-layer nanosilicon-based material according to the present application has the advantages of high specific capacity and good cycle stability, and can be used as a negative electrode material for batteries to prolong the service life and safety of the batteries.

[0046] 3. The method for preparing the double-layered nanosilicon-based material according to the present application, the first instant high-temperature energy fieldization makes the silicon-carbon atoms between the core layer and the first shell layer instantaneously shrink to form silicon-silicon carbide gap through instant in-situ bonding, and the second instant high-temperature energy fieldization makes the silicon-carbon atoms of the first shell layer and the second shell layer instantaneously shrink to form silicon carbide-carbon gap through second instant in-situ bonding, so as to inhibit the volume expansion of the nanosilicon.

[0047] 4. The method for preparing the double-layered nanosilicon-based material according to the present application, the silicon-carbon atoms instantaneously form silicon-carbon chemical bonds through instant in-situ bonding under the instant high-temperature environment, which causes the silicon-carbon interface to shrink to form the double-armor layer of silicon carbide and low-crystallinity carbon, and the double-armor layer has the interface modification effect and plays the role of ion / electron synergistic conduction. BRIEF DESCRIPTION OF DRAWINGS

[0048] The accompanying drawings, which are included to provide a further understanding of the present application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and serve to explain the present application. In the drawings:

[0049] Figure 1 SEM image of the intermediate involved in Example 1 of the present application;

[0050] Figure 2 TEM image of the intermediate involved in Example 1 of the present application;

[0051] Figure 3 SEM image of the double-layered nanosilicon-based material involved in Example 1 of the present application;

[0052] Figure 4 TEM image of the double-layered nanosilicon-based material involved in Example 1 of the present application;

[0053] Figure 5 Performance test diagram of the semi-solid-state battery prepared from the material of Comparative Example 2 of the present application;

[0054] Figure 6 Performance test diagram of the semi-solid-state battery prepared from the double-layered nanosilicon-based material of Example 1 of the present application;

[0055] Figure 7 Performance test diagram of the solid-state full battery cycle performance of the double-layered nanosilicon-based material of Example 1 of the present application. DETAILED DESCRIPTION

[0056] The present application will be described in detail below with reference to the examples, but the present application is not limited to these examples.

[0057] Unless otherwise specified, the raw materials in the examples and comparative examples of the present application are purchased through commercial channels.

[0058] The methods used in the examples and comparative examples of the present application are conventional methods in the art unless otherwise specified.

[0059] Example 1

[0060] The present example relates to a method for preparing a double-layer nanometer silicon-based material, comprising the following steps:

[0061] (1) uniformly mixing fluorinated starch (molecular weight 500,000), fluorinated phenolic resin (molecular weight 1,000,000), and tetrafluoroethylene (molecular weight 1,000,000) in a weight ratio of 1:2:5 to obtain fluorinated organic matter, placing silicon material (particle size 5 μm) and the fluorinated organic matter (particle size 30 μm) in a weight ratio of 1:10 in a water-ethanol solvent, and mixing by ultrasonic stirring for 1 h to obtain mixed slurry A, the weight of the water-ethanol solvent being 4 times the total weight of the silicon material and the fluorinated organic matter, and the weight ratio of water to ethanol being 1:10, and spray drying the mixed slurry A at 200°C to obtain mixed material A;

[0062] (2) subjecting the mixed material A to first-time high-temperature energy field treatment by Joule heating to obtain an intermediate body coated with a first shell layer, the first-time high-temperature energy field treatment being at a temperature rising rate of 1000°C / s to 1300°C for 0.2 h;

[0063] (3) placing the intermediate body and fluorinated phenolic resin (molecular weight 1,000,000, particle size 30 μm) in a weight ratio of 10:1 in a water-ethanol solvent, and mixing by ultrasonic stirring for 0.5 h to obtain mixed slurry B, the weight of the water-ethanol solvent being 4 times the total weight of the intermediate body and the fluorinated phenolic resin, and the weight ratio of water to ethanol being 1:5, and spray drying the mixed slurry B at 200°C to obtain mixed material B;

[0064] (4) subjecting the mixed material B to second-time high-temperature energy field treatment by Joule heating to obtain a double-layer nanometer silicon-based material coated with a second shell layer, the second-time high-temperature energy field treatment being at a temperature rising rate of 1000°C / s to 900°C for 0.1 h.

[0065] Example 2

[0066] The difference between the present example and Example 1 is that the first-time high-temperature energy field treatment is at a temperature rising rate of 1000°C / s to 1400°C for 0.2 h, and the second-time high-temperature energy field treatment is at a temperature rising rate of 1000°C / s to 1000°C for 0.1 h.

[0067] Example 3

[0068] The difference between this embodiment and Embodiment 1 is that the first instantaneous high-temperature energy field treatment is performed by heating to 1350°C at a heating rate of 1000°C / s for 0.2 hours, and the second instantaneous high-temperature energy field treatment is performed by heating to 1000°C at a heating rate of 1000°C / s for 0.1 hours.

[0069] Example 4

[0070] This embodiment relates to a method for preparing a bilayer nano-silicon-based material, including the following steps:

[0071] (1) Fluorinated starch (molecular weight of 50,000), fluorinated phenolic resin (molecular weight of 200,000), and vinylidene fluoride (molecular weight of 10 million) in a weight ratio of 2:2:4 were uniformly mixed to obtain fluorinated organic matter. Silicon material (particle size of 10 μm) and fluorinated organic matter (particle size of 60 μm) in a weight ratio of 1:3 were placed in a water-ethanol solvent and ultrasonically stirred for 0.5 h to obtain mixed slurry A. The weight of water-ethanol solvent was 4 times the total weight of silicon material and fluorinated organic matter, and the weight ratio of water to ethanol was 1:8. Mixed slurry A was spray-dried at 200℃ to obtain mixed material A.

[0072] (2) The mixture A was subjected to a single instantaneous high-temperature energy field treatment by Joule heating to obtain an intermediate with the first shell layer covering the core layer. The single instantaneous high-temperature energy field treatment was performed by heating to 1350℃ at a heating rate of 1000℃ / s for 0.2h.

[0073] (3) The intermediate and fluorinated phenolic resin (molecular weight of 200,000 and particle size of 60 μm) with a weight ratio of 10:1 were placed in a water-ethanol solvent and ultrasonically stirred for 0.5 h to obtain mixed slurry B. The weight of the water-ethanol solvent was 4 times the total weight of the intermediate and fluorinated phenolic resin, and the weight ratio of water to ethanol was 1:10. Mixed slurry B was spray-dried at 200℃ to obtain mixed material B.

[0074] (4) The mixture B is subjected to a second instantaneous high-temperature energy field treatment by Joule heating to obtain a double-layer nano-silicon-based material with a second shell covering the intermediate. The second instantaneous high-temperature energy field treatment is to heat to 1000℃ at a heating rate of 1000℃ / s for 0.1h.

[0075] Example 5

[0076] The difference between this embodiment and embodiment 4 is that the instantaneous high-temperature energy field treatment is carried out by heating to 1250°C at a heating rate of 1000°C / s for 0.2 hours.

[0077] Example 6

[0078] The embodiment is different from embodiment 4 in that the one-time high-temperature energy field treatment is to heat to 1200℃ at a heating rate of 900℃ / s for 0.2h, and the second-time high-temperature energy field treatment is to heat to 900℃ at a heating rate of 1000℃ / s for 0.1h.

[0079] Embodiment 7

[0080] The embodiment relates to a preparation method of a double-layer nanometer silicon-based material, which comprises the following steps:

[0081] (1) fluorinated starch (molecular weight: 100000), fluorinated phenolic resin (molecular weight: 5000000) and vinylidene fluoride (molecular weight: 2000000) with a weight ratio of 1:1:6 are uniformly mixed to obtain fluorinated organic matter, silicon material (particle size: 15μm) and the fluorinated organic matter (particle size: 60μm) with a weight ratio of 1:3 are placed in a water-ethanol solvent, and are mixed for 0.5h through ultrasonic stirring to obtain mixed slurry A, the weight of the water-ethanol solvent is 2 times the total weight of the silicon material and the fluorinated organic matter, and the weight ratio of water to ethanol is 1:5, and the mixed slurry A is spray dried at 200℃ to obtain mixed material A;

[0082] (2) the mixed material A is subjected to one-time high-temperature energy field treatment through Joule heating to obtain an intermediate of a first shell layer coated on a core layer, and the one-time high-temperature energy field treatment is to heat to 1350℃ at a heating rate of 900℃ / s for 0.5h;

[0083] (3) the intermediate and the fluorinated phenolic resin (molecular weight: 200000, particle size: 60μm) with a weight ratio of 10:1 are placed in a water-ethanol solvent, and are mixed for 0.5h through ultrasonic stirring to obtain mixed slurry B, the weight of the water-ethanol solvent is 4 times the total weight of the intermediate and the fluorinated phenolic resin, and the weight ratio of water to ethanol is 1:5, and the mixed slurry B is spray dried at 200℃ to obtain mixed material B;

[0084] (4) the mixed material B is subjected to second-time high-temperature energy field treatment through Joule heating to obtain a double-layer nanometer silicon-based material of a second shell coated on the intermediate, and the second-time high-temperature energy field treatment is to heat to 1000℃ at a heating rate of 1000℃ / s for 0.3h.

[0085] Embodiment 8

[0086] The embodiment relates to a preparation method of a double-layer nanometer silicon-based material, which comprises the following steps:

[0087] (1) the fluorinated starch (molecular weight 100 million), fluorinated phenolic resin (molecular weight 50 million), tetrafluoroethylene (molecular weight 200 million) with a weight ratio of 4:2:2 are uniformly mixed to obtain fluorinated organic matter, the silicon material (particle size 10 μm) and the fluorinated organic matter (particle size 60 μm) with a weight ratio of 1:3 are placed in a water-ethanol solvent, and are mixed by ultrasonic stirring for 0.5 h to obtain mixed slurry A, the weight of the water-ethanol solvent is 8 times the total weight of the silicon material and the fluorinated organic matter, and the weight ratio of water to ethanol is 1:5, and the mixed slurry A is spray dried at 200 ℃ to obtain mixed material A;

[0088] (2) the mixed material A is subjected to one-time instantaneous high-temperature energy field treatment by Joule heating to obtain an intermediate body coated with a first shell layer, and the one-time instantaneous high-temperature energy field treatment is heated to 1350 ℃ at a heating rate of 1000 ℃ / s for 0.5 h;

[0089] (3) the intermediate body and the fluorinated phenolic resin (molecular weight 50 million, particle size 60 μm) with a weight ratio of 10:1 are placed in a water-ethanol solvent, and are mixed by ultrasonic stirring for 0.5 h to obtain mixed slurry B, the weight of the water-ethanol solvent is 4 times the total weight of the intermediate body and the fluorinated phenolic resin, and the weight ratio of water to ethanol is 1:3, and the mixed slurry B is spray dried at 200 ℃ to obtain mixed material B;

[0090] (4) the mixed material B is subjected to two-time instantaneous high-temperature energy field treatment by Joule heating to obtain a double-layer nano silicon-based material coated with a second shell body, and the two-time instantaneous high-temperature energy field treatment is heated to 1000 ℃ at a heating rate of 1000 ℃ / s for 0.2 h.

[0091] Example 9

[0092] The present embodiment relates to a preparation method of a double-layer nano silicon-based material, comprising the following steps:

[0093] (1) the fluorinated starch (molecular weight 100 million), fluorinated phenolic resin (molecular weight 500 million), tetrafluoroethylene (molecular weight 200 million) with a weight ratio of 4:2:2 are uniformly mixed to obtain fluorinated organic matter, the silicon material (particle size 10 μm) and the fluorinated organic matter (particle size 60 μm) with a weight ratio of 1:3 are placed in a water-ethanol solvent, and are mixed by ultrasonic stirring for 0.5 h to obtain mixed slurry A, the weight of the water-ethanol solvent is 8 times the total weight of the silicon material and the fluorinated organic matter, and the weight ratio of water to ethanol is 1:5, and the mixed slurry A is spray dried at 200 ℃ to obtain mixed material A;

[0094] (2) the mixed material A is subjected to one-time instantaneous high-temperature energy field treatment by Joule heating to obtain an intermediate body coated with a first shell layer, and the one-time instantaneous high-temperature energy field treatment is heated to 1350 ℃ at a heating rate of 1000 ℃ / s for 0.5 h;

[0095] (3) The intermediate and fluorinated phenolic resin (molecular weight 100 million, particle size 60 μm) with a weight ratio of 10:1 were placed in a water-ethanol solvent, and mixed by ultrasonic stirring for 0.5 h to obtain mixed slurry B. The weight of the water-ethanol solvent was 4 times the total weight of the intermediate and fluorinated phenolic resin, and the weight ratio of water to ethanol was 1:3. The mixed slurry B was spray dried at 200°C to obtain mixed material B;

[0096] (4) The mixed material B was subjected to secondary instantaneous high-temperature energy fieldization by Joule heating to obtain a double-layer nano-silicon-based material with a second shell covering the intermediate. The secondary instantaneous high-temperature energy fieldization was at a heating rate of 1000°C / s to 900°C for 0.4 h.

[0097] Example 10

[0098] This example relates to a method for preparing a double-layer nano-silicon-based material, comprising the following steps:

[0099] (1) The fluorinated starch (molecular weight 100 million), fluorinated phenolic resin (molecular weight 500 million), and tetrafluoroethylene (molecular weight 200 million) were uniformly mixed to obtain fluorinated organic matter. The silicon material (particle size 30 μm) and the fluorinated organic matter (particle size 60 μm) with a weight ratio of 1:3 were placed in a water-ethanol solvent, and mixed by ultrasonic stirring for 0.5 h to obtain mixed slurry A. The weight of the water-ethanol solvent was 4 times the total weight of the silicon material and the fluorinated organic matter, and the weight ratio of water to ethanol was 1:10. The mixed slurry A was spray dried at 200°C to obtain mixed material A;

[0100] (2) The mixed material A was subjected to primary instantaneous high-temperature energy fieldization by Joule heating to obtain an intermediate with a first shell covering the core layer. The primary instantaneous high-temperature energy fieldization was at a heating rate of 1000°C / s to 1250°C for 1.5 h.

[0101] (3) The intermediate and fluorinated phenolic resin (molecular weight 100 million, particle size 60 μm) with a weight ratio of 10:1 were placed in a water-ethanol solvent, and mixed by ultrasonic stirring for 0.5 h to obtain mixed slurry B. The weight of the water-ethanol solvent was 4 times the total weight of the intermediate and fluorinated phenolic resin, and the weight ratio of water to ethanol was 1:3. The mixed slurry B was spray dried at 200°C to obtain mixed material B;

[0102] (4) The mixed material B was subjected to secondary instantaneous high-temperature energy fieldization by Joule heating to obtain a double-layer nano-silicon-based material with a second shell covering the intermediate. The secondary instantaneous high-temperature energy fieldization was at a heating rate of 1000°C / s to 800°C for 0.4 h.

[0103] Example 11

[0104] The embodiment relates to a preparation method of a double-layer nanometer silicon-based material, which comprises the following steps:

[0105] (1) fluorinated starch (molecular weight: 100,000), fluorinated phenolic resin (molecular weight: 5,000,000) and tetrafluoroethylene (molecular weight: 2,000,000) are uniformly mixed in a weight ratio of 1:1:6 to obtain fluorinated organic matter, silicon material (particle size: 12 μm) and the fluorinated organic matter (particle size: 60 μm) are placed in a water-ethanol solvent, and are mixed for 0.5 h through ultrasonic stirring to obtain mixed slurry A, the weight of the water-ethanol solvent is 4 times the total weight of the silicon material and the fluorinated organic matter, and the weight ratio of water to ethanol is 1:3, and the mixed slurry A is spray dried at 200 DEG C to obtain mixed material A;

[0106] (2) the mixed material A is subjected to one-time flash heating and high-temperature energy field treatment to obtain an intermediate of a first shell layer covering a core layer, the one-time flash heating and high-temperature energy field treatment is to heat at a heating rate of 900 DEG C / s to 1350 DEG C for 0.5 h;

[0107] (3) the intermediate and the fluorinated phenolic resin (molecular weight: 1,000,000, particle size: 60 μm) are placed in a water-ethanol solvent in a weight ratio of 10:1, and are mixed for 0.5 h through ultrasonic stirring to obtain mixed slurry B, the weight of the water-ethanol solvent is 4 times the total weight of the intermediate and the fluorinated phenolic resin, and the weight ratio of water to ethanol is 1:3, and the mixed slurry B is spray dried at 200 DEG C to obtain mixed material B;

[0108] (4) the mixed material B is subjected to two-time flash heating and high-temperature energy field treatment to obtain a double-layer nanometer silicon-based material of a second shell covering the intermediate, the two-time flash heating and high-temperature energy field treatment is to heat at a heating rate of 1000 DEG C / s to 800 DEG C for 0.2 h.

[0109] Embodiment 12

[0110] The embodiment relates to a preparation method of a double-layer nanometer silicon-based material, which comprises the following steps:

[0111] (1) fluorinated starch (molecular weight: 100,000), fluorinated phenolic resin (molecular weight: 300,000,000) and tetrafluoroethylene (molecular weight: 400,000,000) are uniformly mixed in a weight ratio of 2:2:4 to obtain fluorinated organic matter, silicon material (particle size: 15 μm) and the fluorinated organic matter (particle size: 60 μm) are placed in a water-ethanol solvent, and are mixed for 0.5 h through ultrasonic stirring to obtain mixed slurry A, the weight of the water-ethanol solvent is 4 times the total weight of the silicon material and the fluorinated organic matter, and the weight ratio of water to ethanol is 1:2, and the mixed slurry A is spray dried at 200 DEG C to obtain mixed material A;

[0112] (2) The mixture A is subjected to first transient high-temperature energy field treatment by resistance wire heating to obtain an intermediate with a first shell layer covering the core layer. The first transient high-temperature energy field treatment is carried out at a temperature rising rate of 800 ℃ / s to 1100 ℃ for 4 h;

[0113] (3) The intermediate and fluorinated phenolic resin (molecular weight: 1 million, particle size: 60 μm) with a weight ratio of 10:1 are placed in a water-ethanol solvent, mixed by ultrasonic stirring for 0.5 h to obtain a mixed slurry B. The weight of the water-ethanol solvent is 4 times the total weight of the intermediate and the fluorinated phenolic resin, and the weight ratio of water to ethanol is 1:2. The mixed slurry B is spray dried at 200 ℃ to obtain the mixture B;

[0114] (4) The mixture B is subjected to second transient high-temperature energy field treatment by Joule heating to obtain a double-layer nano-silicon-based material with a second shell layer covering the intermediate. The second transient high-temperature energy field treatment is carried out at a temperature rising rate of 1000 ℃ / s to 900 ℃ for 0.5 h.

[0115] Example 13

[0116] The difference between this example and Example 12 is that the first transient high-temperature energy field treatment is carried out at a temperature rising rate of 100 ℃ / s to 1100 ℃ for 4 h.

[0117] Example 14

[0118] The difference between this example and Example 12 is that the second transient high-temperature energy field treatment is carried out at a temperature rising rate of 100 ℃ / s to 900 ℃ for 0.5 h.

[0119] Example 15

[0120] The difference between this example and Example 12 is that the second transient high-temperature energy field treatment is carried out at a temperature rising rate of 1000 ℃ / s to 1200 ℃ for 0.5 h.

[0121] Example 16

[0122] The difference between this example and Example 12 is that the second transient high-temperature energy field treatment is carried out at a temperature rising rate of 1000 ℃ / s to 1500 ℃ for 0.5 h.

[0123] Example 17

[0124] This example relates to a preparation method of a double-layer nano-silicon-based material, comprising the following steps:

[0125] (1) The silicon material (particle size 2 μm) and fluorinated epoxy resin (molecular weight 1 million, particle size 0.1 μm) with a weight ratio of 1:0.3 were placed in a water-ethanol solvent, mixed by ultrasonic stirring for 2 h to obtain mixed slurry A, the weight of the water-ethanol solvent was 8 times the total weight of the silicon material and the fluorinated organic material, and the weight ratio of water to ethanol was 1:3. The mixed slurry A was spray dried at 120°C to obtain mixed material A;

[0126] (2) The mixed material A was subjected to one-time high-temperature energy field treatment by Joule heating to obtain an intermediate with a first shell layer covering the core layer. The one-time high-temperature energy field treatment was at a temperature rising rate of 1500°C / s to 1450°C for 0.2 h;

[0127] (3) The intermediate and fluorinated phenolic resin (molecular weight 1 million, particle size 60 μm) with a weight ratio of 0.5:1 were placed in a water-ethanol solvent, mixed by ultrasonic stirring for 2 h to obtain mixed slurry B, the weight of the water-ethanol solvent was 4 times the total weight of the intermediate and the fluorinated phenolic resin, and the weight ratio of water to ethanol was 1:3. The mixed slurry B was spray dried at 120°C to obtain mixed material B;

[0128] (4) The mixed material B was subjected to two-time high-temperature energy field treatment by Joule heating to obtain a double-layer nanometer silicon-based material with a second shell layer covering the intermediate. The two-time high-temperature energy field treatment was at a temperature rising rate of 1500°C / s to 1200°C for 0.05 h.

[0129] Example 18

[0130] This example relates to a method for preparing a double-layer nanometer silicon-based material, comprising the following steps:

[0131] (1) The silicon material (particle size 50 μm) and fluorinated phenolic resin (molecular weight 1 million, particle size 200 μm) with a weight ratio of 1:15 were placed in an acetone-n-hexane solvent, mixed by ultrasonic stirring for 2 h to obtain mixed slurry A, the weight of the acetone-n-hexane solvent was 4 times the total weight of the silicon material and the fluorinated organic material, and the weight ratio of acetone to n-hexane was 1:1. The mixed slurry A was spray dried at 300°C to obtain mixed material A;

[0132] (2) The mixed material A was subjected to one-time high-temperature energy field treatment by Joule heating to obtain an intermediate with a first shell layer covering the core layer. The one-time high-temperature energy field treatment was at a temperature rising rate of 50°C / s to 550°C for 4 h;

[0133] (3) The intermediate and fluorinated phenolic resin (molecular weight 1 million, particle size 30 μm) with a weight ratio of 3:1 were placed in methylpyrrolidone solvent, and mixed by ultrasonic stirring for 2 h to obtain mixed slurry B. The weight of methylpyrrolidone solvent was 4 times the total weight of the intermediate and fluorinated phenolic resin. The mixed slurry B was spray dried at 300°C to obtain mixture B;

[0134] (4) The mixture B was subjected to secondary instantaneous high-temperature energy fieldization by Joule heating to obtain a double-layer nano silicon-based material with the intermediate coated by the second shell. The secondary instantaneous high-temperature energy fieldization was performed at a temperature rising rate of 50°C / s to 550°C for 1 h.

[0135] Comparative Example 1

[0136] The difference between this comparative example and Example 8 is that the spray drying in step (1) and step (3) is replaced by oven drying, and the temperature of the oven drying is 80°C.

[0137] Comparative Example 2

[0138] The difference between this comparative example and Example 8 is that steps (3) and (4) are not performed, and the intermediate in step (2) is the final product.

[0139] Comparative Example 3

[0140] The difference between this comparative example and Example 8 is that the primary instantaneous high-temperature energy fieldization in step (2) is replaced by a normal calcination process, and the calcination is performed at a temperature rising rate of 5°C / min to 1300°C for 6 h.

[0141] Comparative Example 4

[0142] The difference between this comparative example and Example 8 is that the secondary instantaneous high-temperature energy fieldization in step (4) is replaced by a normal calcination process, and the calcination is performed at a temperature rising rate of 5°C / min to 1000°C for 6 h.

[0143] Comparative Example 5

[0144] The difference between this comparative example and Example 8 is that the weight ratio of the silicon material and the fluorinated organic matter in step (1) is 1:20.

[0145] Comparative Example 6

[0146] The difference between this comparative example and Example 8 is that the weight ratio of the intermediate and the fluorinated phenolic resin in step (3) is 0.2:1.

[0147] Comparative Example 7

[0148] The difference between this comparative example and Example 8 is that the weight ratio of the intermediate and the fluorinated phenolic resin in step (3) is 13:1.

[0149] Test Example 1

[0150] The final materials prepared in the above examples and comparative examples were tested for particle size, specific surface area, pore volume, pore size, and the thickness of the first shell layer, the thickness of the second shell layer, and the crystallinity of the second shell layer, and the test results are shown in Table 1. The specific test methods are as follows:

[0151] Particle size: particle size analysis method;

[0152] Specific surface area: N2adsorption-desorption method;

[0153] Pore volume: T-plot method;

[0154] Pore size: T-plot method;

[0155] Thickness of the first shell layer and thickness of the second shell layer: transmission electron microscopy analysis method;

[0156] Crystallinity of the second shell layer: X-ray single crystal diffraction combined with Scherrer formula calculation method.

[0157] Table 1

[0158]

[0159] Figure 1 and Figure 2 respectively are SEM and TEM images of the intermediate of Example 8, Figure 3 and Figure 4 respectively are SEM and TEM images of the double-layered nanosilicon-based material of Example 8, from Figures 1-4 It can be seen that the particle size of the double-layered nanosilicon-based material and the intermediate does not change significantly, but the shell thickness increases significantly.

[0160] Test Example 2

[0161] The final materials prepared in the above examples and comparative examples were used as active materials, and the active materials, acetylene black, and binders were prepared into negative electrode sheets according to a weight ratio of 90:5:5, with copper foil as the current collector, sulfide solid electrolyte as the electrolyte, and indium-plated lithium sheet as the counter electrode to assemble into semi-solid batteries. The batteries were subjected to electrochemical performance tests, and the test results are shown in Table 2.

[0162] Table 2

[0163]

[0164] Figure 5 The performance test results of the semi-solid batteries prepared from the material of Comparative Example 2, Figure 6 are the performance test results of the semi-solid batteries prepared from the double-layered nanosilicon-based material of Example 1,Figure 7 The graph shows the cycle performance of the solid-state full battery prepared from the bilayer nano-silicon-based material in Example 1. Figure 5 , 6 The comparison shows that the first-stage efficiency of the bilayer nano-silicon-based material improved from 78.44% to 84.30%, demonstrating a significant enhancement in rate performance. From... Figure 7 It can be seen that the solid-state full battery prepared by the bilayer nano-silicon-based material has a cycle stability of 90.16%@124 cycles, and has broad application prospects.

[0165] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a bilayer nanosilicon-based material, characterized in that, It comprises the following steps: (1) mixing silicon material, fluorinated organic matter in a weight ratio of 1: (0.3-15) in a solvent to obtain mixed slurry A, and then spray drying the mixed slurry A to obtain mixture A; (2) subjecting the mixture A to one-time high-temperature energy field treatment to obtain an intermediate of a first shell layer coated on a core layer; (3) mixing the intermediate and fluorinated organic matter in a weight ratio of (0.5-10): 1 in a solvent to obtain mixed slurry B, and then spray drying the mixed slurry B to obtain mixture B; (4) subjecting the mixture B to two-time high-temperature energy field treatment to obtain a double-layer nano-silicon-based material of a second shell layer coated on the intermediate; In step (2), the one-time high-temperature energy field treatment has a heating rate of 50-1500 ℃ / s, a treatment temperature of 550-1450 ℃, and a time of 0.2-4 h; In step (4), the two-time high-temperature energy field treatment has a heating rate of 50-1500 ℃ / s, a treatment temperature of 550-1200 ℃, and a time of 0.05-1 h.

2. The production method according to claim 1, characterized by, The fluorinated organic matter is selected from at least one of fluorinated starch, fluorinated phenolic resin, fluorinated epoxy resin, fluorine-containing plastic, fluorobenzene, and freon, and has a molecular weight of 50-1000 million; The fluorinated organic matter has a particle size of 0.1-200 μm.

3. The method of claim 1, wherein, In step (1), the silicon material has a particle size of 2-50 μm.

4. The method of claim 1, wherein, In steps (1) and (3), the spray drying is performed at a temperature of 120-300 ℃; and / or In steps (1) and (3), the mixing time is 0.5-2 h.

5. The bi-layer nanosilicon-based material produced by the method of any one of claims 1-4, characterized by, It comprises a core layer, a first shell layer, and a second shell layer from inside to outside; The core layer is nano-silicon, the first shell layer is a silicon carbide layer with a thickness of 1.1-5.0 nm, and the second shell layer is a carbon layer with a thickness of 1.1-4.2 nm; The core layer and the first shell layer form a carbon-silicon bond, and the first shell layer and the second shell layer form a carbon-silicon bond; The second shell layer has a crystallinity of 10-90%.

6. The bi-layer nanosilicon-based material of claim 5, wherein, The particle size of the double-layer nanometer silicon-based material is 20-210 nm, the specific surface area is 1-60.0 m 2 / g, the pore size is 0.8-3.0 nm, and the pore volume is 0.01-0.1 cm 3 / g.

7. A battery, characterized by It comprises the double-layer nano-silicon-based material prepared by the preparation method of the double-layer nano-silicon-based material according to any one of claims 1-4 or the double-layer nano-silicon-based material according to any one of claims 5-6.

8. Application of the double-layer nano-silicon-based material prepared by the preparation method of the double-layer nano-silicon-based material according to any one of claims 1-4 or the double-layer nano-silicon-based material according to any one of claims 5-6 in an energy storage device.

Images