Nanostructured silicon material for use in lithium-ion based secondary batteries and method of manufacture

Abstract

The invention relates to a silicon-based material consisting of at least silicon particles, wherein the silicon particles are nanostructured and are of micro-size, wherein the nanoporous structure of the particles comprises oriented channels that completely penetrate the silicon particles and connect two opposite surfaces of the particles, and to a method for manufacturing a silicon-based material consisting of at least silicon particles as described above, comprising the production of a solidified eutectic metal silicide silicon structure consisting of a metal silicide phase and a silicon phase by a controlled oriented solidification process of a eutectic metal silicon melt, and the formation of a nanoporous structured silicon by a chemical etching process to dissolve the metal silicide phase in the solidified eutectic metal silicide silicon structure.

Description

Technical Field

[0001] This invention relates to a method for manufacturing silicon-based particles. The invention also relates to particles having a nanoporous structure.

[0002] Furthermore, the present invention relates to an anode of a lithium-based battery containing the silicon material and a lithium-based battery having such an anode. Background Technology

[0003] Silicon is a high-capacity lithium host material. Compared to graphite, it has ten times the lithium-ion storage capacity. Therefore, silicon can be used as an anode material in high-energy-density lithium-ion-based secondary batteries. However, a major obstacle to the application of silicon is the high volume change associated with the lithium-silicon alloying process. This volume change causes mechanical failures in silicon-containing anodes, such as particle breakage or separation of silicon particles from other materials in the anode or metal electrode. To overcome this failure, the anode composition and silicon structure in such anodes must also be carefully designed.

[0004] It is known that silicon powder with a particle size larger than approximately 0.5 μm will fracture and break down when transformed into a lithium-silicon alloy during battery cycling. It is also known that nanoscale silicon structures can prevent crack formation during cycling. Therefore, once the particle size of nanoscale silicon powder is below the stability limit of approximately 150 nm–200 nm, it can cycle stably. However, nanoscale silicon powder is very difficult to handle in industrial processes, and large-scale industrial production is expensive.

[0005] One approach to overcoming the difficulty of handling nanoscale silicon powder in secondary batteries is to agglomerate nanoscale silicon particles within micron-sized carbon particles (scaffold particles, garnet particles). The drawback of this method is the need for additional, complex, and expensive material handling steps, resulting in high material costs.

[0006] Another strategy for using silicon in lithium-ion based secondary batteries is to fabricate silicon as micron-sized powders with internal nanostructures to overcome breakage problems. This approach can address mechanical issues such as crack formation during lithiation and the breaking of silicon within the anode substrate. In micron-sized particle form, this silicon material is highly compatible with existing anode manufacturing processes.

[0007] An example of this submicron structured porous silicon in lithium-ion battery anodes is described in:

[0008] US2018069234(A1) Nexeon; Electroactive materials for metal-ion batteries;

[0009] US2015072240(A1)LG Chem; Porous silicon-based particles, methods for their preparation, and lithium secondary batteries containing porous silicon-based particles.

[0010] These references disclose methods for metal (Ag, Cu)-assisted etching applied to micrometer-sized silicon particles (US2018069234(A1) and US2015072240(A1)). This method allows for the partial transformation of this silicon material into nanostructured particles. Due to the nature of the etching process, the structured silicon particles consist of an "unstructured silicon" core required to prevent the disintegration of the structured portions of the etched silicon.

[0011] The next step in manufacturing an anode containing such silicon particles is to form a slurry, which is then coated onto a metal foil using processes such as a doctor blade or a die coating process.

[0012] More specifically, the anode coating process involves mixing nanoscale structured silicon material with a binder material (e.g., polyacrylic acid) and conductive carbon (e.g., carbon black, carbon nanotubes, or carbon fibers) in a solvent (e.g., water). It may also include the addition of synthetic or natural graphite powder. The materials are mixed with the solvent to obtain a liquid slurry that can be coated onto a metal electrode (e.g., copper foil). After a drying process, this coated metal foil can be shaped to a specific size and bonded to other components (e.g., a separator layer and a cathode in a secondary battery).

[0013] These processes are well known and have been described in, for example, in the literature of Junying Zhang et al.: High-Columbic-Efficiency Lithium Battery Based on Silicon Particle Materials, Nanoscale Research Letters, Issue: 1, Volume: 10, Pages: 395-395. Oct 8, 2015.

[0014] While this process produces anodes with reasonable performance, the resistance between the silicon particles and the conductive carbon is often high. To improve the performance of such anodes, an additional silicon surface coating step can be applied. Examples of amorphous carbon coatings produced in a high-temperature carbonization process under argon atmosphere are described in, for example, the following literature:

[0015] US9559355B2, HydroQuebec, Particulate Anode Materials and Their Preparation Methods.

[0016] Silicon-coated anodes exhibit excellent performance in terms of battery life and charging rate. One drawback is that the additional, frequent high-temperature coating steps increase the manufacturing cost of such anodes.

[0017] The purpose of this invention is to overcome or mitigate one or more disadvantages of the prior art. Summary of the Invention

[0018] The objective is achieved by the method for manufacturing silicon-based particles according to claim 1. This invention discloses a silicon material composed of micron-sized particles and a method for manufacturing such a silicon material, wherein each particle has a nanostructure. Compared to the prior art, this manufacturing method allows the particles to be fully structured, overcoming the limitations of unstructured volume within the particles to prevent disintegration. The nanostructures in such particles take the form of through-holes or channels extending through the particles and connecting two surfaces of the particles. Optionally, if the channels branch within the particles, the channels can connect two or more surfaces. Compared to the prior art, which discloses pores having a single opening on one surface, these channels are more efficient at transporting liquid electrolytes into the silicon. Compared to the prior art, the improved electrolyte transport performance combined with the fully structured particles results in better battery performance, higher capacity, and improved charge and discharge rates.

[0019] This manufacturing method also discloses a carbon coating applied to silicon without requiring additional process steps. In the prior art, carbon coatings are applied using high-temperature carbonization or coating steps such as chemical vapor deposition. Such additional processing steps are eliminated by the disclosed method.

[0020] Furthermore, the present invention relates to a powder of silicon-based particles according to claim 13. The present invention also relates to an anode for a secondary battery and a lithium-based secondary battery. Attached Figure Description

[0021] The invention will now be explained in more detail with reference to the accompanying drawings, in which exemplary embodiments of the invention are illustrated. The drawings are for illustrative purposes only and are not intended to limit the scope of the invention. The scope of the invention is limited only by the definitions given in the appended claims.

[0022] Figure 1 The layered structure of a lithium-ion-based secondary battery with different components is shown;

[0023] Figure 2 The composition of an anode consisting of structured silicon, conductive carbon, and binder on a metal electrode is shown.

[0024] Figure 3 A surface scanning electron microscope image of a cross-section of an anode comprising this structured silicon material is shown;

[0025] Figure 4 This image shows a scanning electron microscope photograph of the surface of submicron structured silicon powder particles;

[0026] Figure 5 An example of particle size distribution measurement for a micron-sized nanoporous silicon particle sample with a median (D50) particle size of 7.9 μm is shown;

[0027] Figure 6A , Figure 6B This is a schematic diagram of submicron structured silicon particles, illustrating the phase transition geometry during the first charge of a secondary battery.

[0028] Figure 7A , Figure 7B This is a schematic diagram of submicron structured silicon particles in a charged (left) and discharged (right) state;

[0029] Figure 8 The X-ray photon emission spectrum of this micron-sized silicon powder at energies close to the C1s peak of carbon is shown; and

[0030] Figure 9 The charge / discharge efficiency—coulombic efficiency—of nanoscale structured silicon anodes is shown compared to that of unstructured silicon anodes. Detailed Implementation

[0031] Figure 1 The layered structure of a lithium-ion-based secondary battery with different components is shown.

[0032] like Figure 1 As illustrated, the lithium-ion-based secondary battery comprises a layered stack including an anode, a separator, and a cathode. 1002 is the anode of battery 1000, which, in this invention, primarily comprises nanoscale structured silicon material and incorporates binder materials to improve mechanical stability and conductive additives to improve conductivity. 1003 is a separator layer made of an electrically insulating material that allows electrolyte permeation (e.g., porous polypropylene foil or fiberglass cloth). Separator layer 1003 prevents short circuits between the anode 1002 and the cathode 1004, which would lead to catastrophic failure of the secondary battery. 1004 represents the active cathode layer, which contains lithium-containing metal oxides or metal phosphides and has conductive additives for improving conductivity and binders for mechanical stability. The secondary battery stack is filled with a lithium-ion-containing electrolyte 1005.

[0033] During charging of battery 1000, lithium ions are drawn from cathode 1004 and transported and stored in anode 1002. During discharging of battery 1000, anode 1002 releases the stored lithium ions, which are then transported back to cathode 1004. Clearly, the total energy density of battery 1000 with stacked anode layer 1004 and cathode layer 1002 is primarily determined by the specific lithium storage capacity of the materials in the anode and cathode and their relative Li / Li ratio. + The chemical potential for the transformation is provided. Therefore, cathode and anode materials with high specific capacity and large potential difference for lithium ions are preferred.

[0034] An example of advanced anode materials is silicon, which has approximately 10 times the specific capacity compared to graphite. This silicon material can be converted into Li₂ with a specific capacity of 3590 mAh / g. 3.75 Si alloy.

[0035] However, converting silicon into Li 3.75 The processes of silicon (Si) and their opposites cause significant volume expansion and contraction of the silicon material during each battery cycle. These volume changes induce mechanical stresses in the silicon material itself and in the surrounding anode structure, thus leading to rapid capacity decay of the battery.

[0036] To overcome this failure, the silicon material and its interactions with other components in the anode must be designed to mitigate the volume expansion of the silicon material during cycling. This will result in a stable anode and thus a stable cell.

[0037] A first embodiment of the present invention describes a method for manufacturing silicon materials, said silicon materials comprising advantageous carbon surface coatings of silicon and their application in high energy density lithium-ion secondary battery systems.

[0038] The method described in detail below includes three processing steps:

[0039] Step 1: Rapidly and directionally solidify a metal-silicon melt with a eutectic ratio or a near-eutectic ratio metal-silicon system into a solid binary phase material composed of a metal silicide phase and a silicon phase.

[0040] Step 2: Dissolve the metal silicide phase in the cured material using a wet chemical etching process, and then...

[0041] Step 3: Grind the etched cured material that has come into contact with the carbon-containing material.

[0042] The details of these three steps are described below:

[0043] The first step in the silicon material manufacturing method involves a rapid directional solidification step of a liquid silicon-metal melt. As an example of an implementation, the process is described in the form of a liquid silicon-chromium melt; however, combinations of silicon with other metals such as titanium or vanadium can be used as substitutes.

[0044] When a liquid melt of chromium and silicon with a eutectic ratio or a near-eutectic ratio solidifies rapidly, phase separation occurs, and the two-phase structure solidifies as a layered structure of chromium disilicide and silicon phases. Jackson and Hunt (Jackson KA, Hunt JD, Lamellar and rod eutectic growth[J]. Trans Met SocAIME, 1966, 236: 1129-1142.) disclosed a model describing the structural geometry dependent on the crystallization rate.

[0045] The layered or rod-shaped silicide phase and silicon phase extend in the direction of crystallization advance and have typical dimensions (defined as the distance between the chromium disilicide phase and the continuous silicon phase) that depend on the crystallization rate. Therefore, a well-controlled crystallization process that allows for near-constant crystallization rates can be used as a method for manufacturing such uniformly spaced chromium disilicide-silicon materials.

[0046] A preferred crystallization process for the method is described, for example, in DE3419137(A1), for semiconductor foil, wherein an undercooled substrate is transported beneath a casting frame filled with a eutectic melt. The crystallization process begins when the undercooled substrate comes into contact with the melt in the casting frame and continues during the transport time of the substrate in contact with the melt. Since the crystallization direction is perpendicular to the plane of the substrate surface, the layered or rod-shaped structure is also oriented perpendicular to the substrate surface. Because this process allows for high, well-controlled crystal growth rates, the eutectic chromium-silicon melt will crystallize into a well-defined, eutectic two-phase structure. The controllable crystallization rate of the casting process, combined with the chromium-silicon eutectic melt, produces a structured two-phase material, wherein the structural dimensions (i.e., the characteristic distance between a pair of parallel silicon wafer layers) can be tuned within an art-related range of 100 nm to 1500 nm by varying the thermal contact with the substrate and the temperature difference between the substrate and the melt.

[0047] The second step of the method involves the selective etching (and removal) of metal silicides. Most metal silicides can be etched in a diluted hydrogen fluoride solution. Since hydrogen fluoride does not react with silicon, a selective etching process is achieved. As a result of this process, a material sheet in which the metal silicide phase has been removed and a nanoporous silicon structure is obtained.

[0048] The etching process can be carried out at room temperature; however, higher temperatures can be used to enhance chemical reactivity. The concentration of the hydrogen fluoride solution can be adjusted to improve yield and shorten processing time, and to optimize the use of the etchant during the process. It is also known that most of the reaction components can be recycled in the form of metal oxides, silicon oxide, and hydrogen fluoride. Therefore, the etching process is well-suited for producing nanoporous structured silicon materials through a recycling process with minimal byproduct waste.

[0049] As the final step in the etching process, the etched silicon material is removed from the etchant and rinsed in water.

[0050] The final step is to grind the etched nanostructured silicon material to obtain micron-sized silicon powder. Ball milling or drum milling are methods that can be applied in this process depending on the expected production volume; however, continuous grinding processes with selective particle size filtration (e.g., jet milling) may be preferred for larger-scale production.

[0051] Although milling will produce micron-sized silicon powder with the desired nanostructure porosity, it will not produce optimal conductivity when the milled silicon material is contained in an anodic coating.

[0052] Figure 4 This image shows a scanning electron microscope (SEM) image of the surface of submicron structured silicon powder particles within micron-sized silicon powder. Typical average particle sizes range from 1 μm to 20 μm. The nanoscale structure of the particles reveals oriented channels extending through the particles and connecting their two surfaces; in this example, typical channel sizes range from 100 nm to 500 nm. The orientation of the channels can be seen as pores on surface 4001 (corresponding to channels at surface 4002), depending on the particle orientation in the image.

[0053] Figure 5 An example of the particle size distribution of this micron-sized silicon powder is shown. In this example, the average particle size (D50) is 7.9 μm, while D10 = 2.7 μm and D90 = 17.5 μm. It should be understood that the particle size distribution can be adjusted during the grinding process. Due to practical reasons in the battery manufacturing process, an average particle size of 1 μm to 20 μm is preferred.

[0054] According to an embodiment of the present invention, the grinding of the silicon material is carried out in contact with a carbon-containing material. This carbon-containing material may include at least one of carbon black, graphite, hard carbon, carbon nanotubes, graphene, acetylene black, and carbon fiber, but is not limited thereto.

[0055] During the grinding process, the silicon wafer material continuously fractures, creating a silicon surface with reactive dangling bonds. These dangling bonds can react with carbon-containing materials or carbon-containing grinding equipment components involved in the grinding process to form silicon carbide bonds with carbon-containing aggregates or particles. Therefore, the carbon-containing aggregates or particles consist of carbon-containing materials chemically bonded to the surface of the silicon particles. Possibly, the carbon-containing aggregates or particles form a coating that partially or completely covers the outer surface of the silicon particles.

[0056] As an example, adding 1% to 10% carbon black during the milling step showed improved conductivity between silicon particles and the anode structure and increased cycle life of batteries produced with such an anode.

[0057] Dry polishing is preferred for the polishing step to allow contact between the newly broken dangling bonds in silicon and the carbon-containing material. In wet polishing, the dangling bonds on the silicon surface are highly likely to react with the humid environment, while in dry polishing, they are more likely to chemically bond with conductive carbon particles.

[0058] Another improvement is to perform the grinding step under a protective atmosphere, such as a gas like argon. The protective atmosphere will hinder the competitive reaction between silicon dangling bonds and atmospheric oxygen.

[0059] Figure 8 The X-ray photon emission spectrum of submicron structured silicon powder, produced according to the present invention and ground in contact with carbon black powder, is shown at energies close to the carbon C1s peak 7001. The higher energy portion of the spectrum 7002 shows the presence of CO bonds, while the lower energy portion 7003 shows the presence of Si-C bonds. In this example, the carbon black particles are chemically bonded to the silicon surface in the form of a carbon coating.

[0060] The combination of milled silicon materials and exposed carbon materials produces nanostructured, micron-sized carbon-coated silicon materials, which exhibit improved performance when combined with other components in the anode of a lithium-ion secondary battery. The significant improvement in the conductivity of the silicon material in the anode increases the anode's performance, while the nanostructure of silicon allows for stable electrical cycling and prevents crack formation or anode delamination, as will be shown in the application examples below.

[0061] In another embodiment, the etching and polishing steps are performed in reverse order. The cured two-phase material can first be polished to produce a powder consisting of particles with a metal silicide-silicon two-phase structure. Carbon-silicon bonding can be achieved in a manner similar to that described in the above embodiments. After the polishing step, the powder is selectively etched in the process described above. This dissolves the metal silicide phase and produces a nanoporous silicon material according to the invention.

[0062] According to the implementation plan, an additional mechanical fracturing step is added after the curing step to produce metal silicide-silicon parts from the casting of the cured material. This additional step can advantageously provide material parts that can be processed more efficiently in subsequent chemical treatments.

[0063] According to the implementation scheme, the reaction with carbon-containing materials in the grinding step can be omitted to produce nanostructured silicon particles. In this case, the nanostructured silicon particles typically form a natural silica surface. Nanostructured silicon particles with a natural silica surface can be used, for example, in combination with a coating process that depends on the presence of the silica surface to react with organic molecules.

[0064] Example ( Figure 3 ):

[0065] Figure 3 An embodiment of this silicon-containing anode is shown. A surface scanning electron microscope cross-section of the anode, comprising a structured silicon material 3002, carbon black 3003, and binder contained on a copper foil 3001, is shown.

[0066] The anode composition in this embodiment contains 80% by weight of nanoporous structured silicon, which has been contact-milled with 5% by weight of carbon black. During slurry preparation, 5% by weight of graphite powder is added to a polyacrylic acid solution. The final anode composition consists of 80% by weight of silicon, 5% by weight of carbon black, 5% by weight of graphite, and 10% by weight of polyacrylic acid.

[0067] If the silicon-containing anode of the composition is combined with, for example, a lithium nickel manganese cobalt oxide cathode (NMC), the capacities of the anode and cathode are preferably matched in such a way that the silicon-containing anode is charged to a specific capacity of 1000 mAh / g to 2000 mAh / g, which is much lower than the maximum capacity of silicon at 3590 mAh / g.

[0068] Therefore, this matching will enable the silicon-containing anode of this embodiment to have an areal capacity of 3 mAh / cm². 2 The lithium nickel manganese cobalt oxide cathode (NMC) is combined. If the areal loading of silicon is adjusted to, for example, 1.5 mg / cm²... 2 Or 3mg / cm 2 Then the silicon material will be at 2000mAh / g (1.5mg / cm³). 2 Specific capacity (load) and 1000mAh / g (3mg / cm³) 2 The specific capacity of the load is high. This application, which includes silicon-based anodes, offers significant advantages in terms of cycle life and stable battery performance.

[0069] It was observed that when silicon is alloyed with lithium, silicon undergoes two phase transitions. Silicon transforms into crystalline Li. 3.75 Si first transforms into amorphous Li. 3.4 Si phase. If lithiation is limited to below Li... 3.4 The Si ratio is approximately 3200 mAh / g, indicating a two-phase material composition, in which a portion of the silicon material transforms into Li. 3.4 Si, while another part of silicon remains in its crystalline state.

[0070] The advantage of this use of silicon (i.e., capacity-limited loading (limited lithiation as described above)) is that the remaining crystalline silicon phase mechanically stabilizes the silicon particles and forces them to expand into the internal pores of the particles. This effect significantly reduces the mechanical load on the anode component and improves battery cycle stability. It also prevents external expansion of the battery containing the silicon anode, one of the main obstacles to the application of silicon-dominant anodes.

[0071] refer to Figure 6A , Figure 6B and Figure 7A , Figure 7B The impact of capacity-limited loads will be explained in more detail. Figure 6A , Figure 6B A schematic diagram of submicron structured silicon particles during the first charge is shown. The original silicon particle size is 5000 ( Figure 6A It consists of pure crystalline silicon phase 5001. During the first charge cycle, the crystalline silicon is transformed into amorphous Li. 3.4 Si phase 5002. During the first charge, crystalline silicon (silicon phase) 5001 and amorphous Li... 3.4 Si phase 5002 coexist ( Figure 6B Depending on the amount of lithiation, the material can be completely transformed into amorphous Li. 3.4 Si phase. At even higher lithiation levels, Li phase will exist. 3.75 Silicon alloys composed of Si. Capacity-limited cycling is far less efficient than complete conversion to Li. 3.4 Given the capacity of the Si phase, the two phases in the material will continue to coexist.

[0072] Figure 7A , Figure 7B This demonstrates the effect of continuous charging under capacity-limited battery cycles (…). Figure 7A ) and discharge ( Figure 7B A schematic diagram of submicron structured silicon particles 6000 during the lithium-containing (charged) state. The lithium-containing silicon particles consist of two phases: crystalline silicon 6001 and amorphous Li. 3.4 Composed of Si 6006. After discharge, amorphous Li 3.4 The Si phase transforms into amorphous silicon 6003. During continuous cell cycling with the same or lower capacity, only amorphous silicon Li... 3.4 The Si volume is in an active state. The remaining crystalline silicon 6001 does not change significantly and will remain mechanically stable (porous) particles.

[0073] Figure 9 The charge / discharge efficiency—coulombic efficiency—of silicon anodes is shown. Reference numeral 8001 indicates the relationship between coulombic efficiency and cycling for two samples containing nanostructured silicon materials according to the invention. Reference numeral 8002 indicates the relationship between coulombic efficiency and cycling for micron-sized unstructured silicon. Both materials have the same particle size distribution and anode composition. Anodes were prepared using 80 wt% silicon, 10 wt% conductive carbon, and 10 wt% polyacrylic acid as a binder. Cycling was performed on lithium metal disks, with the silicon capacity limited to 1000 mAh / g. Test cycles with two hours of charge time and two hours of discharge time were used for all samples.

[0074] This embodiment demonstrates the application of nanostructured micron-sized coated carbon particles produced using a method according to an embodiment of the present invention.

[0075] The invention has been described with reference to preferred embodiments. Upon reading and understanding the foregoing detailed description, obvious modifications and variations will occur to others. The invention is intended to be construed as including all such modifications and variations, provided they fall within the scope of the appended claims.

Claims

1. A method for manufacturing nanostructured, micrometer-sized silicon particles, said silicon particles containing a plurality of parallel-oriented nanometer-sized channels connecting at least two surfaces of said particles, said method comprising: - A eutectic metal-silicon melt is produced by combining metals and silicon as components; - The eutectic metal-silicon melt is brought into contact with an undercooled substrate, and a solidified eutectic metal-silicon plate or sheet composed of a metal silicide phase and a silicon phase is produced through a controlled directional solidification process of the eutectic metal-silicon melt. The solidified eutectic metal-silicon plate or sheet is formed in the solidified eutectic metal-silicon plate or sheet with the silicon phase sheets or rods and the metal silicide phase sheets or rods parallel to each other in a direction perpendicular to the substrate. - The nanostructured, micron-sized silicon particles are produced by exposing the cured eutectic metal silicide wafer or sheet to a polishing step and providing a selective etching step. The etching step includes exposure to a selective chemical etching process configured to dissolve the sheets or rods of the metal silicide phase in a directionally solidified layered or rod-shaped eutectic casting structure, and to form parallel-oriented channels in the silicon phase at the locations of the dissolved sheets or rods of the metal silicide phase, such that each of the nanostructured, micrometer-sized silicon particles is provided with a channel that completely penetrates the nanostructured, micrometer-sized silicon particle and connects at least two surfaces of the nanostructured, micrometer-sized silicon particle at each location of the dissolved sheets or rods of the metal silicide phase, the average particle size of the nanostructured, micrometer-sized silicon particle being 1 µm to 20 µm, and the diameter of the parallel-oriented channels in the nanostructured, micrometer-sized silicon particle being 100 nm to 1000 nm.

2. The method according to claim 1 further includes a step of grinding the cured eutectic metal silicide silicon plate or wafer after the etching step.

3. The method according to claim 1 further includes a step of grinding the cured eutectic metal silicide silicon plate or wafer prior to the etching step.

4. The method according to any one of claims 1 to 3, wherein the grinding process is selected from ball milling, drum milling, and jet milling.

5. The method of claim 2, further comprising, when the polishing step is performed after the etching step: - During the grinding process, a silicon surface with reactive dangling bonds is generated, and a carbon-containing material is added to the generated silicon surface with reactive dangling bonds to provide chemical bonding of carbon-based polymers to the outer surface of the nanostructured and micron-sized silicon particles, for generating carbon-based polymers on the outer surface of the nanostructured and micron-sized silicon particles, wherein the carbon-containing material comprises at least one selected from carbon black, graphite, carbon nanotubes, graphene, and carbon fibers.

6. The method according to claim 5, wherein the carbon black is in the form of hard carbon.

7. The method according to claim 6, wherein the carbon black is in the form of acetylene black.

8. The method of claim 5, further comprising forming a silicon carbide layer between the nanostructured, micrometer-sized silicon particles and the outer surface of the carbon-based polymer or carbon-based particles.

9. The method according to any one of claims 1 to 6, wherein the metal in the silicon melt is chromium, and the crystallization rate of the cast structure during the controlled directional solidification is equal to or greater than 0.1 mm / s.

10. The method according to any one of the preceding claims, wherein the minimum thickness of the wall between two parallel-oriented channels in the nanostructured and micron-sized silicon particles is 100 nm to 1000 nm.

11. A method for producing the anode of a secondary battery from a powder of silicon particles with at least nanostructured and micron-sized particles, said nanostructured and micron-sized silicon particles being manufactured by the method according to any one of claims 1 to 10.

12. A powder of nanostructured, micron-sized silicon particles manufactured by the method according to any one of claims 1 to 10.

13. The powder of claim 12, wherein the nanostructured and micron-sized silicon particles are micron-sized and each has a nanoporous structure, the nanoporous structure comprising at least one channel that completely penetrates the nanostructured and micron-sized silicon particles and connects at least two surfaces of the nanostructured and micron-sized silicon particles.

14. The powder of claim 12, wherein the nanostructured and micron-sized silicon particles are micron-sized and each has a nanoporous structure comprising a plurality of channels that completely penetrate the nanostructured and micron-sized silicon particles and are oriented parallel to each other between at least two surfaces of the nanostructured and micron-sized silicon particles.

15. The powder according to any one of claims 12 to 14, wherein carbon-based polymers or carbon-based particles are present on the outer surface of the nanostructured and micron-sized silicon particles.

16. The powder of claim 15, wherein the nanostructured and micron-sized silicon particles comprise a silicon carbide layer disposed between the outer surface of the nanostructured and micron-sized silicon particles and the carbon-based polymer or carbon-based particles.

17. An anode for a secondary battery, comprising a silicon-based material consisting of at least nanostructured and micrometer-sized silicon particles, wherein the nanostructured and micrometer-sized silicon particles are micrometer-sized and have a nanoporous structure, the nanoporous structure comprising parallel-oriented channels that completely penetrate the nanostructured and micrometer-sized silicon particles and connect two opposing surfaces of the nanostructured and micrometer-sized silicon particles, the nanostructured and micrometer-sized silicon particles being manufactured according to the method of any one of claims 1 to 10.

18. A lithium-based secondary battery having a combination of an anode and a cathode layer according to claim 17, wherein the capacity of the cathode is selected such that the anode is charged to its maximum capacity, at which point nanostructured and micron-sized silicon particles are only partially alloyed into amorphous Li. 3.4 Si phase, and the remainder of each nanostructured and micron-sized silicon particle is composed of the amorphous Li 3.4 Composed of adjacent crystalline silicon phases.

19. The lithium-based secondary battery according to claim 18, wherein the amorphous Li 3.4 The Si phase is formed as a layer on the walls of the parallel-oriented channels in the nanostructured and micron-sized silicon particles, and the amorphous Li is formed. 3.4 The Si phase is surrounded by the crystalline silicon phase in the nanostructured, micron-sized silicon particles.

20. The lithium-based secondary battery according to claim 18 or 19, wherein the capacity of the cathode is selected such that the anode is charged to a capacity of less than 2500 mAh / g silicon.

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