Composite nano-architecture units, multilayer composites and methods of making composite nano-architecture units

Abstract

A composite nano-architectural unit is disclosed. The unit comprises a columnar film grown over another layer, where the columns touch each other at the top to form an arch with optimized properties. This nano-architectural unit, called nano-arch, achieves high mechanical stability of the film under strong and variable stresses.

Description

Technical Field

[0001] This invention relates to Si anodes of LIB and other materials, as well as applications where surface mechanics plays a crucial role. Background Technology

[0002] Alloyed anode materials are a promising alternative to graphite in high-energy lithium-ion batteries (LIBs) due to their theoretical capacity increase of up to 10 times. However, the large volume changes during lithiation hinder the formation of a stable solid electrolyte interface (SEI) and lead to electrode breakage. The low mechanical stability of LIBs with Si anodes is a barrier to their commercialization, but composite anodes containing Si additives are already commercially available. However, the mechanical stability of Si is a major parameter limiting the particle size and fraction of Si in composite anodes. Therefore, increasing the amount of Si in the anode while maintaining satisfactory mechanical stability remains a challenge for high-energy LIB technology. Summary of the Invention

[0003] The problem the invention aims to solve

[0004] The main mechanical problem lies in the compressive stress generated during lithiation, which is subsequently released during delithiation. When this compressive stress exceeds the yield strength, the electrode deforms to accommodate the volume change. Therefore, adjusting the elastic modulus E of the Si anode is crucial. E quantifies the strain in the material when stress (force per unit area, σ) is applied (deformation is defined as the removal of a part to a reference length, ε) (E = σ / ε).

[0005] Therefore, Si electrodes with low E values ​​allow for easy deformation of the material, maximizing anode capacity at the expense of reduced mechanical stability. This problem can be addressed by using a shell to seal the nanostructured Si while maintaining electrode integrity and allowing for the formation of a stable SEI; however, this leads to a reduction in LIB energy density. Another strategy to improve the mechanical stability of Si-based anodes is to increase the anode's elastic modulus by using novel silicon composites with binders or by physically constraining volume expansion. Again, these methods limit LIB energy density.

[0006] Solution for solving the problem

[0007] The present invention was made in view of the above circumstances. In order to solve the above problems, a first aspect of the present invention aims to provide a composite nanoarchitecture unit comprising a columnar film grown on top of another layer, wherein the columns are in contact with each other at the top to form an arch with optimized properties.

[0008] A second aspect of the present invention aims to provide a composite nanostructure unit of the first aspect, wherein the columnar film is an amorphous Si film in an annealed state.

[0009] A third aspect of the invention aims to provide a composite nanostructure unit of the first aspect, wherein a columnar film is grown over a layer of metal nanoparticles.

[0010] A fourth aspect of the invention aims to provide a composite nanostructure unit of the first aspect, wherein optimized properties include at least one of low lithium consumption during the formation of a solid electrolyte interface in a Li-ion battery, high coulombic efficiency, and high mechanical stability associated with any application where the surface of the membrane is under strong and variable stress.

[0011] The fifth aspect of the invention aims to provide a multilayer composite comprising at least two longitudinal repeats of the composite nanostructure unit of the first aspect.

[0012] A sixth aspect of the invention aims to provide a multilayer composite of the fifth aspect, wherein optimized properties, compared to a monolayer structure, include high coulombic efficiency for lithium-ion batteries and mechanical stability of the membrane, indicating enhanced arching effect.

[0013] A seventh aspect of the present invention aims to provide a method for manufacturing a composite nanostructure unit. The method includes the steps of: a) depositing nanoparticles from a vapor phase onto a substrate; and b) growing a columnar film on the nanoparticle layer. The diameter of the columnar film increases with thickness until the tops of the columns contact each other, thereby sealing the surface by forming an arched structure in step b).

[0014] The eighth aspect of the present invention aims to provide a method of manufacturing the seventh aspect, wherein the growth of the columnar membrane is stopped as soon as possible after the arch is formed in step b).

[0015] The ninth aspect of the present invention aims to provide a method of manufacturing the seventh aspect, which further includes the step of c) thermally annealing the columnar film.

[0016] The tenth aspect of the present invention aims to provide a method for manufacturing the seventh aspect, wherein the columnar film is an amorphous Si film.

[0017] The eleventh aspect of the present invention aims to provide a method of manufacturing the seventh aspect, wherein the nanoparticles are metal nanoparticles.

[0018] The effects of the invention

[0019] This work addresses this challenge using a specific columnar thin-film structure known as an arch structure (a novel nanoarchitecture synthesized using nanoparticles). The name alludes to the civil engineering definition of a multi-arch structure supported on columns, characterized by a high elastic modulus. According to the first to eleventh aspects of the invention, nanoparticles are used as a scaffold to grow nanoarch structure units, allowing the composite to be longitudinally repeated in multiple layers, which enhances the optimized properties observed in a single layer. Therefore, Si anodes with arch structures simultaneously exhibit high mechanical stability and low lithium consumption during SEI formation, addressing two major challenges to the commercialization of Si anodes. This optimized electrochemical performance is associated with a significant shift in mechanical behavior precisely when individual Si pillars merge to form a closed arch (but not exceeding this point, where an amorphous Si film is further grown on top). The introduction of the arch structure and arch effect opens up numerous new possibilities for the design of novel materials for batteries, and also for other applications where surfaces are subjected to strong and variable stresses.

[0020] New strategy:

[0021] Adhesive-free

[0022] Solvent-free

[0023] Design flexibility

[0024] Altitude control

[0025] Nanostructure unit:

[0026] Nanostructures of civil engineering buildings

[0027] Reproducible on the Z-axis

[0028] Improved properties

[0029] Properties of optimization:

[0030] Internal gaps

[0031] Sealing surface

[0032] High mechanical stability

[0033] Applications in Li-ion batteries:

[0034] High capacity

[0035] Fast charging / discharging rate

[0036] High coulomb efficiency Attached Figure Description

[0037] [ Figure 1A ] Figure 1A This is a schematic diagram of the columnar growth process of Si amorphous thin films;

[0038] [ Figure 1B ] Figure 1B This is a schematic diagram of the columnar growth process of Si amorphous thin films;

[0039] [ Figure 1C ] Figure 1C This is a schematic diagram of the columnar growth process of Si amorphous thin films;

[0040] [ Figure 1D ] Figure 1D This is a schematic diagram showing the mechanical response of the columnar structure of an amorphous Si film to nanoindenter force;

[0041] [ Figure 1E ] Figure 1E This is a schematic diagram showing the mechanical response of the arched structure of the Si amorphous film to the nano-indenter force;

[0042] [ Figure 1F ] Figure 1F This is a schematic diagram showing the mechanical response of the deposition structure of the Si amorphous film to the nano-indenter force;

[0043] [ Figure 2A ] Figure 2A It is sample 54 V TEM thin section image;

[0044] [ Figure 2B ] Figure 2B It is sample 216 S TEM thin section image;

[0045] [ Figure 2C ] Figure 2C It is sample 54 V SEM top view image;

[0046] [ Figure 2D ] Figure 2D It is sample 216 S SEM top view image;

[0047] [ Figure 2E ] Figure 2E It is sample 54 V SEM cross-sectional image;

[0048] [ Figure 2F ] Figure 2F It is sample 216 S SEM cross-sectional image;

[0049] [ Figure 3A ] Figure 3A Sample 25 is shown. C The morphology and elastic modulus;

[0050] [ Figure 3B ] Figure 3BSample 54 is shown. V The morphology and elastic modulus;

[0051] [ Figure 3C ] Figure 3C Sample 155 is shown. S The morphology and elastic modulus;

[0052] [ Figure 3D ] Figure 3D The E-histograms for several specified samples are shown.

[0053] [ Figure 3E ] Figure 3E The highest weighted E value is shown in the histogram plotted for the film thickness h of all samples;

[0054] [ Figure 4A ] Figure 4A A slice showing a simulated growth of Si deposited on nanoparticles, viewed along the (110) direction;

[0055] [ Figure 4B ] Figure 4B A slice showing a simulated growth of Si without deposited nanoparticles, viewed along the (110) direction;

[0056] [ Figure 4C ] Figure 4C Eight examples of simulated nanoparticle growth are shown, sliced ​​and observed along the (100) direction;

[0057] [ Figure 4D ] Figure 4D The evolution of force-depth curves for eight examples is shown; compression-hold-decompression loops were performed at 500 K using flat diamond carbon tips;

[0058] [ Figure 4E ] Figure 4E The initial linear elastic deformation of eight instances within a 2 nm displacement is shown, fitted by linear regression (solid line);

[0059] [ Figure 4F ] Figure 4F The stiffness of the corresponding structure is shown as a function of thickness;

[0060] [ Figure 5A ] Figure 5A The charge capacity of Si films grown on TaNS and Cu foil substrates is shown (Si electrode delithiation).

[0061] [ Figure 5B ] Figure 5B The coulombic efficiency of half-cells of Si films grown on TaNS and Cu foil substrates at 0.5C cycling between 0.01 and 1V is shown.

[0062] [ Figure 5C ] Figure 5C The charge capacity of Si films grown on TaNS and Li foil substrates is shown (Si electrode delithiation).

[0063] [ Figure 5D ] Figure 5D The coulombic efficiency of half-cells of Si films grown on TaNS and Li foil substrates at 0.5C cycling between 0.01 and 1V is shown.

[0064] [ Figure 6 ] Figure 6 This is a schematic diagram of the experimental setup;

[0065] [ Figure 7A ] Figure 7A The thickness of the Si film deposited on TaNS is shown as a function of sputtering time;

[0066] [ Figure 7B ] Figure 7B The thicknesses of Si films deposited on TaNS of different thicknesses are shown.

[0067] [ Figure 8A ] Figure 8A The X-ray reflectance (XRR) measurement of a typical Cu wafer surface including a natural copper oxide layer is shown.

[0068] [ Figure 8B ] Figure 8B X-ray reflectance (XRR) measurements are shown for Si film growth without pre-deposited Ta nanoparticles.

[0069] [ Figure 8C ] Figure 8C Showing Ta nanoparticles (25) C X-ray reflectance (XRR) measurement of Si film growth on substrates.

[0070] [ Figure 8D ] Figure 8D Showing Ta nanoparticles (54) V X-ray reflectance (XRR) measurement of Si film growth on substrates.

[0071] [ Figure 8E ] Figure 8E Showing Ta nanoparticles (110) S X-ray reflectance (XRR) measurement of Si film growth on substrates.

[0072] [ Figure 8F ] Figure 8F Showing Ta nanoparticles (216) S X-ray reflectance (XRR) measurement of Si film growth on substrates.

[0073] [ Figure 9A ] Figure 9A The relationship between the atomic percentage concentration of Si and Ta and etching time is shown in AR ion etching of a sample co-deposited with Si and Ta using X-ray photoelectron spectroscopy (XPS) in a matrix configuration.

[0074] [ Figure 9B ] Figure 9B The 2p peak of Si is shown in the AR ion etching of a sample co-deposited with Si and Ta, constructed using X-ray photoelectron spectroscopy (XPS) in a matrix configuration.

[0075] [ Figure 9C ] Figure 9C The image shows the 4f peak of Ta etched by Ar ions in a sample co-deposited with Si and Ta using X-ray photoelectron spectroscopy (XPS) to construct a matrix.

[0076] [ Figure 10 ] Figure 10 Sample 25 is grown on a Si substrate. C Cross-sectional images obtained by scanning electron microscopy (SEM);

[0077] [ Figure 11A ] Figure 11A This shows the effect of TaNS (sample 110) on two different substrates (Cu, Si). S Histogram of the elastic modulus of Si sputtered for 60 minutes.

[0078] [ Figure 11B ] Figure 11B The histograms of the elastic modulus of Si sputtered directly onto a substrate without nanoparticles for 60 minutes are shown for two different substrates (Cu and Si).

[0079] [ Figure 12A ] Figure 12A Sample 15 is shown. C and 25 C The elastic modulus is a function of height;

[0080] [ Figure 12B ] Figure 12B Sample 35 is shown. C and 54 V The elastic modulus is a function of height;

[0081] [ Figure 12C ] Figure 12C Sample 110 is shown. S and 155 S The elastic modulus is a function of height;

[0082] [ Figure 12D ] Figure 12D Sample 201 is shownS The elastic modulus is a function of height;

[0083] [ Figure 13A ] Figure 13A The arch structure (54) is shown in the measurement using PF-QNM. V Morphology of an exemplary sample;

[0084] [ Figure 13B ] Figure 13B The arch structure (54) is shown in the measurement using PF-QNM. V Elastic modulus of an exemplary sample;

[0085] [ Figure 13C ] Figure 13C The arch structure (54) is shown in the measurement using PF-QNM. V E-histogram of an exemplary sample;

[0086] [ Figure 13D ] Figure 13D The depositional structure (155) is shown using PF-QNM measurements. S Morphology of an exemplary sample;

[0087] [ Figure 13E ] Figure 13E The depositional structure (155) is shown using PF-QNM measurements. S Elastic modulus of an exemplary sample;

[0088] [ Figure 13F ] Figure 13F The depositional structure (155) is shown using PF-QNM measurements. S E-histogram of an exemplary sample;

[0089] [ Figure 14A ] Figure 14A The image shows a slice along the (100) direction and an observation of Si deposition on a single nanoparticle by MD simulation;

[0090] [ Figure 14B ] Figure 14B The image shows a slice along the (110) direction and an observation of Si deposition on a single nanoparticle by MD simulation;

[0091] [ Figure 14C ] Figure 14C This shows the surface mesh (i.e., without atoms) inside the deposited layer in 3D;

[0092] [ Figure 15 ] Figure 15 This shows Si deposited on two adjacent nanoparticles;

[0093] [ Figure 16A ] Figure 16AShow the corresponding structures during the unloading process (such as...) Figure 4C Elastic deformation (as shown);

[0094] [ Figure 16B ] Figure 16B The pressure relief stiffness of the corresponding structure is shown as a function of the structural thickness;

[0095] [ Figure 17A ] Figure 17A The charge capacity of the Si sample is shown (delithiation of the Si electrode);

[0096] [ Figure 17B ] Figure 17B The coulombic efficiency of the Si sample is shown.

[0097] [ Figure 18A ] Figure 18A It is sample 15 C Low-magnification SEM images after 3 charge-discharge cycles and scratching with a diamond pen;

[0098] [ Figure 18B ] Figure 18B It is sample 54 V Low-magnification SEM images after 3 charge-discharge cycles and scratching with a diamond pen;

[0099] [ Figure 18C ] Figure 18C It is sample 155 S Low-magnification SEM images after 3 charge-discharge cycles;

[0100] [ Figure 18D ] Figure 18D It is sample 15 C Cross-sectional SEM images after 3 charge-discharge cycles and diamond scraping to expose the film edge;

[0101] [ Figure 18E ] Figure 18E It is sample 54 V Cross-sectional SEM images after 3 charge-discharge cycles and diamond scraping to expose the film edge;

[0102] [ Figure 18F ] Figure 18F It is sample 155 S Cross-sectional SEM images after 3 charge-discharge cycles;

[0103] [ Figure 18G ] Figure 18G It is sample 15 C High-magnification SEM image of the anode after three charge-discharge cycles;

[0104] [ Figure 18H ] Figure 18H It is sample 54 V High-magnification SEM image of the anode after three charge-discharge cycles;

[0105] [ Figure 18I ] Figure 18I It is sample 155 S High-magnification SEM image of the anode after three charge-discharge cycles;

[0106] [ Figure 19 ] Figure 19 Electrode 54 in a lithium half-cell is shown. V Volume expansion at 0.5C.

[0107] [ Figure 20A ] Figure 20A The figure shows 54 recorded when the circuit is open after 3 cycles. V and 15 C Nyquist plot.

[0108] [ Figure 20B ] Figure 20B The figure shows 54 recorded when the circuit is open after 10 cycles. V and 15 C Nyquist plot.

[0109] [ Figure 20C ] Figure 20C The figure shows 54 records when the circuit is open after 50 cycles. V and 15 C Nyquist plot.

[0110] [ Figure 20D ] Figure 20D The figure shows 54 recorded when the circuit was open after 75 cycles. V and 15 C Nyquist plot.

[0111] [ Figure 21A ] Figure 21A The charge capacity of the Si sample is shown (delithiation of the Si electrode);

[0112] [ Figure 21B ] Figure 21B The coulombic efficiency of the Si sample is shown.

[0113] [ Figure 22A ] Figure 22A D54 grown on a Si substrate prior to lithiation-delithiation cycles V TEM thin-section image of the sample;

[0114] [ Figure 22B ] Figure 22B D54 grown on a Si substrate prior to lithiation-delithiation cycles VSEM image of the sample;

[0115] [ Figure 23A ] Figure 23A D54 is shown V The elastic modulus of the sample was measured using PF-QNM;

[0116] [ Figure 23B ] Figure 23B It's D54 V and 54 V Histogram of the elastic modulus of the sample;

[0117] [ Figure 24A ] Figure 24A D54 is shown V and 54 V The charged (delithiation) capacity of the LIB half-cell cyclically tested at 0.5C;

[0118] [ Figure 24B ] Figure 24B D54 is shown V and 54 V Coulombic efficiency of the LIB half-cell of the sample after cycling at 0.5C;

[0119] [ Figure 25 ] Figure 25 It is sample D54 after three lithiation-delithiation cycles. V SEM image. Detailed Implementation

[0120] <1. Overview of the Invention>

[0121] Nanomaterials undergoing cyclic swelling-deswelling benefit from internal void spaces that help accommodate significant volume changes. However, this flexibility often comes at the cost of reduced mechanical stability, leading to component degradation and ultimately failure. Here, we identify the optimal building block for a Si-based Li-ion battery (LIB) anode, fabricated using a ligand-free and effluent-free cluster deposition method, and demonstrate its robustness through atomic computer simulations. Columnar amorphous Si films are grown on Ta nanoparticle scaffolds due to their shielding effect. PeakForce quantitative nanomechanical mapping reveals the critical point at which the mechanical behavior changes when the column contacts form an arched structure. The maximization of the resulting mechanical strength depends on the arching effect, a well-known civil engineering concept. The arched nanostructure units seal the electrode surface and reduce the electrode / electrolyte interface while dissipating lithiation stress. Its longitudinal repetition in a double-layered aqueduct-like structure improves the capacity stability and coulombic efficiency of the LIB. These results highlight the development of arching effects at the nanoscale, successfully applying macroscale strategies to mechanically stable nanostructures.

[0122] <2. Detailed Description of the Attached Figures>

[0123] Figure 1A-1F The design strategy of the TaNS-Si amorphous film composite anode and its structural and mechanical relationship are shown. Figure 1A-1C The diagram illustrates the growth process broken down into three steps: TaNS deposition, columnar growth of amorphous Si films utilizing the TaNS masking effect, and thermal annealing at 150°C to enhance mobility and subsequently eliminate porosity at the open surface. The mechanical response under nanoindenter force indicates the characteristics of the three structures studied. Figure 1D columnar, Figure 1E Arched Figure 1F Deposition. The nanoindenter used for PF-QNM measurements is shown above the structure, applying compressive force to the Si sample. White arrows indicate film stress, independent of indentation; the film response under the nanoindenter is shown in yellow. Dashed lines represent sample deformation, and small arrows indicate force distribution within the column.

[0124] Figures 2A-2F The structural features of the Si thin film grown on TaNS are shown. TEM thin-section image of the sample: Figure 2A 54 V and Figure 2B 216 S This illustrates the nanoparticle properties of TaNS and the amorphous properties of Si. A Pt layer was observed during the deposition process. SEM top view image of the sample: Figure 2C 54 V and Figure 2D216 S And the corresponding cross-sectional images: Figure 2E 54 V (Enlarged illustration) and Figure 2F 216 S 54 V Corresponding to an arched structure, where the tops of the columns touch each other, and in 216 S In the structure, the pillars have been merged into a continuous film using a Volmer-Weber growth pattern, as shown in the dome morphology (deposition structure). The substrate used to prepare the sample for characterization of this structure is Si(111).

[0125] Figures 3A-3E The mechanical properties of silicon films of different thicknesses grown on TaNS are shown, measured using PF-QNM. The substrate used to prepare the samples was Si(111), but similar results were obtained for copper foil substrates (Figure 11). Figure 3A Sample 25 is shown. C The morphology and elastic modulus. Figure 3B Sample 54 is shown. V The morphology and elastic modulus. Figure 3C Sample 155 is shown. S The morphology and elastic modulus. For ease of comparison, the same scale is used in the E plots of the three samples; note that 54 V E is saturated in most of the plot. Figure 3D The E histograms for several specified samples are shown. E increases from columnar structures to arched structures (upper histogram), and decreases for sedimentary structures (lower histogram). Figure 3E The histogram showing the highest weighted E values ​​for the film thickness h of all samples is presented. The variation of E with h corresponds to the transition from columnar to island-shaped Si growth, which is the region where the top of the column contacts and forms the arched structure.

[0126] Figures 4A-4F The correlation between morphological and mechanical properties is shown through MD simulation. Figure 4A As shown, Si deposited on Ta nanoparticles at 500 K (replicated along the (100) direction due to periodic boundary conditions) follows columnar growth and forms an arched structure. The simulated frame of the slice is clearly visible when viewed along the (110) direction. The right figure only depicts the surface mesh of the slice inside the deposited layer (i.e., without atoms), indicating the presence of voids. Figure 4B The same is shown, but without TaNS. Depositional structures form from the beginning of deposition, resulting in a large number of voids throughout. Figure 4C Eight instances with TaNS selected from the growth simulation are shown, sliced ​​and viewed along the (100) direction. Figure 4DThe evolution of the force-depth curve is shown; a compression-hold-decompression loop is performed at 500K using a flat diamond carbon tip. Figure 4E The initial linear elastic deformation within a 2 nm displacement is shown, fitted by linear regression (solid line). Figure 4F The diagram shows the stiffness of the corresponding structure as a function of thickness, clearly demonstrating the stiffness of the arch structure, and... Figure 3C The experimental PF-QNM measurements were very consistent.

[0127] Figures 5A-5D Comparative electrochemical properties of Si films grown on TaNS and Cu foil substrates are shown. Figures 5A-5B Representative columnar vs. arched vs. sedimentary structures; Figures 5C-5D : Single-arch structure containing equal amounts of Si vs. double-arch structure. The anode is assembled in a half-cell using Li foil as the reference and counter electrode, and 1.0 M LiPF6 in a 50:50 (w / w) mixture of EC:DEC (ethylene carbonate: diethyl carbonate) as the electrolyte. Figure 5A , Figure 5C Capacity (delithiation from Si electrode), Figure 5B , Figure 5D The coulombic efficiency of a half-cell cycling at 0.5C between 0.01 and 1V.

[0128] Figure 6 A schematic diagram of the experimental setup is shown. A layered structure is formed by the continuous deposition of multilayer Ta nanoparticle scaffolds (condensed by inert gas sputtering via magnetron) and overlapping amorphous Si films (by RF sputtering). Figure 6 Created by Pavel Puchenkov using Blender 2.8 (see: www.blender.org).

[0129] Figures 7A-7B The thickness and roughness of the Si film deposited on TaNS are shown, as measured by XRR. Figures 8A-8F The data and experimental details are provided in the document. Figure 7A The diagram shows the Si film thickness (h) as a function of sputtering time (t). Square dots represent measured data, and circular dots represent interpolated thicknesses at different times. The thickness follows a linear function with respect to time. Figure 7B The roughness of deposited Si films of different thicknesses is shown.

[0130] Figures 8A-8FX-ray reflectance (XRR) measurements of selected samples are shown. The substrate used for these measurements was Cu(100). XRR measurements were performed using a Bruker D8 Discover instrument (Bruker AXS GmbH, Karlsruhe, Germany) equipped with a Cu X-ray source operating at 1600 W with a wavelength of λ = 1.54 Å and using Goebel mirrors. For XRR, a 0.05-mm slit was used to reduce the beam in the reflectivity plane to minimize the radiation footprint at the sample location. After careful alignment of the sample, data were collected from 0.2° to 3° (2θ) in steps of 0.01°. The experimental XRR data were fitted using GenX 2.4.10 software (v.2.4.10, http: / / genx.sf.net). Figure 8A In this simulation, the surface of a typical copper wafer, including a layer of natural copper oxide, is shown. Figure 8B In Figure 8, the Si film growth without pre-deposited Ta nanoparticles shows reflective stripes with 2θ > 0.8°, while the Si film growth on a substrate with Ta nanoparticles does not. Therefore, these stripes belong to the very flat Cu / Si interface that is not present on the deposited Ta nanoparticles. Figure 8B and Figure 8D The silicon in the process uses the same Si deposition time. Figure 8C , Figure 8D , Figure 8E and Figure 8F Corresponding to Si thin film samples with different Si deposition times.

[0131] Figures 9A-9C The estimation of the percentage of Ta in a Si sample using X-ray photoelectron spectroscopy (XPS) is shown. For this purpose, samples with Si and Ta co-deposited for 60 minutes were prepared using a matrix construction (thickness corresponding to 110 s of sample). XPS spectra were obtained using a Kratos AXISUltra DLD photoelectron spectrometer with an Al Ka ​​(1486.6 eV) source and a base voltage of 10⁻¹⁰ mbar. To obtain representative data, XPS measurements were performed at different times of Ar ion etching (ion energy 3 keV). The relationship between the atomic percentage concentrations of Si and Ta and etching time is shown below. Figure 9A As shown, according to Figure 9B , Si 2p peak and Figure 9C Estimate the 4f peak of Ta. The atomic percentage of Si is approximately 95%, while that of Ta is approximately 0.1%. The difference up to a total of 100% is due to O and C (present only in the first measurement). Si oxidation can occur during sample transfer from the glove box to the XPS apparatus.

[0132] Figure 10 Sample 25 grown on a Si substrate is shown. CCross-sectional images from a scanning electron microscope (SEM).

[0133] Figure 11A-11B The influence of the substrate on the elastic modulus measurement is shown. Elastic modulus histogram: Figure 11A Si was sputtered onto TaNS (sample 110S) for 60 minutes. Figure 11B Si was directly sputtered onto a substrate without nanoparticles for 60 minutes. In the presence of TaNS, the energy (E) of the film was independent of the substrate. Alternatively, when deposited directly on Cu or Si(111), E strongly depended on the substrate. This indicates that, in the presence of TaNS (rather than the substrate), Si growth is determined.

[0134] Figure 12A-12D The chart shows the elastic modulus and height as a function of all samples. The correlation coefficient (CC) is displayed in each chart. The correlation coefficient between random variables X and Y is a dimensionless measure of the linear relationship between X and Y, defined as follows:

[0135] [Mathematical Expression 1]

[0136]

[0137] Where cov(X,Y) is the covariance of X and Y, μ X μ Y It is the mean, σ X σ Y These are the standard deviations of variables X and Y, respectively, assuming a specified expected value. Individual variability in X and Y is removed by dividing the product of their means by the product of their standard deviations. The correlation coefficient is always -1 ≤ ρ ≤ 1. A value of 1 means the relationship between X and Y can be perfectly described by a linear equation; therefore, as X increases, Y also increases. A value of -1 means that as X increases, Y decreases. If the correlation coefficient is equal to 0, there is no linear relationship between X and Y.

[0138] Figures 13A-13F The mechanical properties of the unannealed sample, measured using PF-QNM, are shown. The sample preparation process is the same as in Figure 3, except that step 3, i.e., at 8 × 10⁻⁶, is omitted. -3 Heat annealed at 150°C for 60 minutes under Ar pressure of millibars. Figure 13A , Figure 13B and Figure 13C The arched structure (54) is shown V The morphology, elastic modulus, and E-histogram of an exemplary sample. Figure 13D , Figure 13E and Figure 13F The sedimentary structure (155) is shown. SThe morphology, elastic modulus, and E-histogram of exemplary samples were analyzed. A significant decrease in E-values ​​was observed in the annealed samples (i.e., average ~60-70 GPa) compared to the annealed samples, which had an average of ~120 GPa. In contrast, annealing (or lack thereof) had no significant effect on the latter, showing an average of ~40-50 GPa, similar to the annealed samples. This control experiment confirms the importance of hot annealing for strengthening arched structures, resulting in the formation of stiffer individual columns through movement and subsequent elimination of voids.

[0139] Figures 14A-14C The simulation shows Si deposition on a single Ta nanoparticle. Both the simulation frame and the nanoparticle are larger than [a certain size]. Figures 4A-4F (That is, a side length of 16.4 nm and a diameter of 8 nm, respectively), to clearly study the size effect. In addition, settings were made with... Figures 4A-4F The same applies (i.e., due to periodic boundary conditions, the simulation frame replicates along the (100) direction at a temperature of 500 K). Again, the Si film follows columnar growth and forms an arched structure. To clearly observe this, slices of the simulation frame are taken along... Figure 14A (100) and Figure 14B (110) Directional observation. Figure 14C The right figure depicts the surface mesh (i.e., without atoms) inside the deposited layer in 3D, indicating the presence of voids.

[0140] Figure 15 The image shows Si deposited on two adjacent Ta nanoparticles. In this simulation set, the two Ta nanoparticles are explicitly introduced into a simulation frame that is twice as long to avoid... Figures 4A-4F The simulation shown exhibits symmetry. In addition, the settings and... Figures 4A-4F The simulation frame is identical (i.e., due to periodic boundary conditions, it is replicated along the (100) direction at a temperature of 500 K). Similarly, the Si film follows columnar growth, eventually forming an arched and deposited structure. For clear observation, the simulation frame is sliced ​​and viewed along the (100) direction. A snapshot is taken from the film, where the evolution of the growth can be clearly estimated.

[0141] Figures 16A-16B The elastic deformation during the unloading process is shown. Figure 16A ,like Figure 4C The stiffness of the corresponding structure shown is extracted from the slope of the linear fitted line of the curve (solid line). Figure 16B Unlike the loading process, the decompression stiffness decreases monotonically as a function of the structural thickness. The red dashed line indicates the nonlinear fit by the following mathematical formula 2.

[0142] Verification of porosity values ​​provided by MD:

[0143] The porosity of deposited amorphous silicon structures is strongly influenced by sputtering conditions and temperature, as these parameters determine the mobility of adsorbed atoms. The porosity obtained through our MD simulations can be estimated by comparing the number density of Si atoms in the porous structure with a reference number density in a bulk amorphous silicon sample, the volume of which can be measured through surface structure analysis. Such analyses yield porosity values ​​of ~0.3.

[0144] In an elastic state, the deposited structure can be approximated by a spring, where the stiffness is inversely proportional to the length: [Equation 2]

[0145]

[0146] Where A is the cross-sectional area, E is the elastic modulus, and L is the length. For this structure, the cross-sectional area A is 10.89 nm × 10.89 nm. The relationship between elastic modulus and porosity has been extensively studied. It is estimated to be...

[0147] [Mathematical Expression 3]

[0148] E = E0(1-p) 2

[0149] Where p is the porosity; therefore, from the unloading stiffness, we can calculate the volume Young's modulus E0 as 75 GPa, which is in good agreement with the literature value, thus verifying our method.

[0150] Figures 17A-17B The LIB performance of Si samples exhibiting different behaviors based on their structure and E properties is shown. Figure 17A The capacitance (lithiation of Si electrode) and... Figure 17B The coulomb efficiency is shown.

[0151] Figure 18A-18I It is sample 15 C ( Figure 18A , Figure 18D , Figure 18G ), 54 V ( Figure 18B , Figure 18E , Figure 18H ) and 155 S ( Figure 18C , Figure 18F , Figure 18I SEM images after three charge-discharge cycles at 0.5C between 0.01V and 1V. Imaging the physical condition of the electrode after cycling can help interpret its electrochemical behavior. Once the electrode was delithiated, the half-cell was opened in an Ar glove box, the anode was cleaned with dimethyl carbonate and dried under high vacuum. Low-magnification images ( Figures 18A-18C (This shows the effect of scratching with a diamond pen at 15) C and 54 VThe ripples formed on the sample; Sample 155 S No similar scratching is needed, Sample 155 S This shows highly fractured film-forming islands. (Cross-section) Figure 18D-18F The diagram shows columnar and arched structures at the corrugated edges, as well as sample 155. S The separation membrane is located at the edge of the cracked island. This can separate 155 S The high coulombic efficiency and simultaneous high capacity decay observed are not attributed to the exposure of the new electrode to the electrolyte, but rather to the loss of active material. High-magnification top-down image of the anode after cycling ( Figure 18G-18I This illustrates the formation of the pore. The pore is at 15... C and 54 V The channels are particularly prevalent in the structure and can be attributed to the electrolyte during cycling, most likely related to activation (during which more active material is involved in the lithiation process during cycling).

[0152] Figure 19 The volume expansion of the electrode at 54V in a lithium half-cell at 0.5C is shown, based on estimates by VLChevrier et al. (VLChevrier, L. Liu, DB Le, J. Lund, B. Molla, K. Reimer, LJ Krause, LD Jensen, E. Figgemeier, K. W. Eberman, J. Electrochem. Soc. 2014, 161, A783).

[0153] Figure 20A-20D The figure of 54 was recorded when the circuit was open after several cycles. V and 15 C The Nyquist plot. Resistance at high frequencies is related to the electrode / electrolyte interface resistance (SEI and charge transfer), 15 C The resistance ratio is 54 V The sample's resistance was three times higher. This confirms that the higher electrode / electrolyte interface in the columnar structure leads to a larger SEI.

[0154] Figures 21A-21B The LIB performance of Si samples exhibiting different behaviors based on their structure and E properties is shown. Figure 21A Capacity (lithiation of Si electrode) and Figure 21B Coulomb efficiency. These values ​​are close to 100%, but are not important because capacity decay indicates that the sample has become fractured.

[0155] Figures 22A-22B D54 grown on a Si substrate prior to lithiation-delithiation cycle is shown. V Characteristics of the sample. Figure 22A TEM thin section image, Figure 22BSEM images. It is clearly a double-arched structure, rather than using the same amount of Si and a single TaNS (110). S The sedimentary structures created by ).

[0156] Figures 23A-23B D54 is shown V Mechanical properties of the sample measured using PF-QNM. Figure 23A , modulus of elasticity (most plots are saturated because the scale is the same as that used in Figure 3), and Figure 23B The corresponding histogram. The histogram shows D54. V and 54 V Comparison between samples.

[0157] Figure 24A D54 is shown V and 54 V The charged (delithiation) capacity of the LIB half-cell cyclically tested at 0.5C. Figure 24B The coulombic efficiency of the same sample is shown.

[0158] Figure 25 It is sample D54 after three lithiation-delithiation cycles. V SEM images of the sample. The sample is grown on copper foil so that the anode can operate in a half-cell. The bilayer structure is retained after charge-discharge cycles.

[0159] <3. Overview of Design Strategies and Arch Structure Concept>

[0160] Samples were grown directly on the substrate via continuous and independently controlled clustered beam deposition (CBD) of Ta nanoparticles and RF sputtering of Si thin films. Figure 6 This setup enables the fabrication of binder-free, high-purity thin films (grown under high vacuum conditions) with excellent control over film thickness and nanoparticle size and shape. First, crystalline Ta nanoparticles are deposited (…). Figure 1A Step 1) forms a porous nanoparticle film, which serves as a nanoscaffold (denoted as TaNs) for Si anode fabrication. Subsequently, Si films of varying thicknesses are sputtered onto the TaNs at an acute angle to utilize the shielding effect of the TaNs; this results in Si initially growing in a columnar structure. Figure 1A Step 2). The column diameter increases with the thickness until the tops of the columns touch each other, closing the surface by forming an arched (bow-shaped) structure. Figure 1B Further Si deposition forms a continuous amorphous film through an island-like (island) growth pattern, labeled as the depositional structure. Figure 1C Subsequent hot annealing ( Figure 1AStep 3) enhances defect mobility and is eventually eliminated on the surface of each structure. In the case of columnar structures, this process increases their rigidity. Conversely, in deposited structures, voids remain trapped within the Si layer because their migration barriers to certain free surfaces are significantly higher, thus forming a sponge-like porous film.

[0161] Variations in the structure of Si films profoundly affect their mechanical properties. In the PeakForce quantitative nanomechanical mapping (PF-QNM) measurements performed here, a nanoindenter applied a vertical force above each structure. Figure 1D-1F (gray arrow). In columnar structures, compressive stress causes each column to maintain its shape and character. Figure 1D (White arrow). The columns are easily deformed until they come into contact with each other, where a clamping effect prevents further deformation. This causes E to increase with membrane thickness, due to the increased proximity of the columns. An extreme case occurs in arched structures (…). Figure 1E In this structure, the tops of the columns are already in contact with each other; as a result, clamping occurs immediately under the force of the nanoindenter, without initial deformation, and a high E value is measured. This effect is analogous to the arching action described in civil engineering, where an arch transfers stress to the ground and responds by pushing outward. In sedimentary structures ( Figure 1F E is related to the dome shape; under the force from the nanoindenter, Si atoms at the peak easily diffuse into the valley. E is also affected by the underlying porosity of the softened Si layer. Therefore, it exhibits a low E value.

[0162] Arched structures can serve as nanostructural units capable of dissipating lithiation (or other) stresses while avoiding cracking observed in deposited structure-based electrodes. When arched structures are longitudinally repeated (i.e., arched nanostructures are repeatedly deposited on top of each other, each layer forming a single arched nanostructural unit), thin-film electrodes are formed that increase the amount of Si active material while maintaining optimized mechanical and surface stability during battery cycling. Most importantly, the concept of nanoarchitectures as repeating nanostructural units can be widely applied to the design of novel materials requiring high stress tolerance.

[0163] <4. Correlation between morphology and mechanical properties>

[0164] Subsequently, the samples were processed according to scheme h. X The naming convention is as follows: h is the film thickness (in nm), and X represents the structure type: C (columnar), V (arched), and S (deposition).

[0165] The nanoporous TaNS consists of crystalline Ta nanoparticles (3 nm in diameter, narrow size distribution) 12a and 14. Due to the soft landing capability of CBD, these nanoparticles retain their individual characteristics. (15 Transmission electron microscopy (TEM) thin section image) Figure 2A , 2B The results show that the TaNS thickness is ~10 nm, confirming the amorphous nature of the overlying Si layer. The Si film thickness increases linearly with time at a rate of 1.69 nm min⁻¹ (via X-ray reflection (XRR)). Figures 7A-7B , Figures 8A-8F Although, as can be seen through X-ray photoelectron spectroscopy (XPS), Figures 9A-9C The estimated Ta content was less than 0.5 at.%, but its induced particle morphology ( Figure 2D The high roughness of the subsequent Si film (in the range of 3.3-3.8 nm, compared to 0.8 nm when Si is grown directly on the substrate) is due to the 2D aspect ratio. Figures 7A-7B ).

[0166] Sample 54 V The exhibit shows columns with increasing diameters, resembling an inverse truncated cone with top contact, forming an arched structure as seen in cross-sectional scanning electron microscopy (SEM). Figure 2E This columnar structure (begins to form at the start of the Si growth stage) Figure 10 , 25 C) is due to the shielding effect of TaNS, which disrupts the incident beam of Si atoms. (In 216...) S A columnar structure was also observed at the bottom. Figure 2F However, as more Si is deposited on the dome layer, the Si layer becomes continuous rather than having a long-range structural order due to the amorphous nature of sputtered Si. Subsequently, a dome forms above the continuous film, reducing the local surface energy.

[0167] These domes initially bear compressive stress until they reach their limit, at which point the stress becomes tensile. This causes Si adsorbed atoms to diffuse from the peaks to the valleys. As the domes merge, the thickness of the continuous film increases, which is typical for island-shaped (island) film growth modes.

[0168] Sample 25 measured using an atomic force microscope (AFM) operated in PeakForce tapping mode via the PF-QNM. C 54 V and 155 S The morphology and elastic modulus plots show the nanoscale peaks and valleys. Figure 3A Si samples were prepared on Si(111) for these measurements, although the E measurement was valid for any substrate when TaNS was deposited between the substrate and sputtered Si. Figure 11A-11B All sedimentary samples showed a very strong correlation between morphology and E characteristics (~1). Figure 12A-12DTherefore, the peaks and valleys of E are related to surface morphology. The correlation decreases for arched structures (0.8), while the correlation decreases significantly for columnar structures (dispersion values ​​in the range of 0-0.6). This suggests that factors other than surface morphology also contribute to the peaks and valleys of E, which may be related to the presence of honeycomb-like density defect regions (pore networks) in columnar structures and 54 V This is related to the presence of incomplete arches.

[0169] The distribution of E values ​​in the plot is shown in the histogram. Figure 3B The thickness of each sample is correlated with the peak value of the E-value. Figure 3C Samples with columnar structures show a polynomial increase with film thickness, for 15... C and 25 C The values ​​(~40 GPa) are similar, which may be related to TaNS. E increases with film thickness until the columns come into contact with each other to form multiple arches, and E reaches its maximum value, with extremely high values ​​as high as 250 GPa. The E value of the deposited structure is similar to that of the columnar structure (~40 GPa) and is independent of film thickness.

[0170] Control experiments omitting step 3 of the manufacturing process confirm the importance of thermal annealing for reinforcing columnar structures (rather than deposited structures) by moving and subsequently eliminating voids. Figures 13A-13F The strong correlation with the morphology image suggests that E measurements are constrained by the dome structure of the Si surface. This differs from columnar and arched samples where the particle surface represents the top of a column.

[0171] <5. Explaining Structure and Mechanical Properties Through Atomic Simulation>

[0172] A set of molecular dynamics (MD) simulations were performed to model the deposition process of the TaNS-Si film composite on a rotating substrate holder. In the presence of Ta nanoparticles, the vicinity of the nanoparticles is shielded by deposited Si atoms, such as... Figure 4A As shown, the left figure (see also) Figures 14A-14C , Figure 15 Therefore, columnar structures initially form above the Ta nanoparticles. With prolonged deposition time, the columns coalesce, initially forming arches, and eventually forming the deposited structure, which is in excellent agreement with experimental results. Conversely, in the control simulation without nanoparticles ( Figure 4B The sedimentary structure begins to form from the depositional process. Therefore, it can be clearly demonstrated that the shading effect of TaNS is crucial for the formation of arched structures.

[0173] Surface structure analysis emphasizes the location and size of pores within the deposited structure, such as Figure 4A , Figure 4BThe gray surface grid in the right figure is shown. In the same simulation, large voids formed only within the deposition region, and the estimated porosity increased from 0.09 to 0.3. This can be explained by the finite size effect of the columnar structure. Small vacancy clusters near the open surface can be rapidly filled by small displacements of surface atoms or newly deposited atoms. In contrast, the larger voids formed beneath the surface of the deposition structure require collective movement of Si atoms, which is significantly slower. Furthermore, the activation enthalpy (migration barrier) for self-diffusion in amorphous Si is approximately 2.7 eV; therefore, once large voids are formed within the deposition region, they remain stable under annealing conditions.

[0174] The mechanical properties measured by PF-QNM are interpreted by simulating a compression-holding-decompression circuit. For example... Figure 4C As shown, we selected eight examples with nanoparticles from the first set of simulations. The evolution of the feedback force can be tracked with time and the displacement of the plates above the Si layer. The feedback force clearly distinguishes different stages, such as... Figure 4D As shown by the dashed line. From the force vs. displacement curves, we extracted the stiffness of the structure during the loading stage, such as... Figure 4E As shown by the solid line in the image.

[0175] Clearly, the stiffness reaches its maximum when the columnar structure evolves into an arched structure, such as... Figure 4F As shown, this is the same as Figure 3C The experimental PF-QNM measurements are very similar. This can be explained by the fact that in the initial elastic deformation region (displacement from 1 nm to 2 nm), the arched structure (i.e., the case of 20.8–26.3 nm) achieves a combination of maximum contact area, minimum porosity, and relatively small thickness. The stiffness extracted from the decompression stage (where the contact area of ​​all structures is approximately the same) follows a spring-like behavior with a porosity of 0.3. Figures 16A-16B ).

[0176] <6. Arched structure as building block for LIB electrodes>

[0177] Typically reported Si anode fracture is associated with extensive volumetric expansion (300-400%) due to accumulated mechanical stress in the electrode. This effect limits the thickness and size of Si films and nanoparticles used as LIB anodes, respectively. Sputtering Si films on rough substrates can improve electrode stability during cycling, but the film thickness remains limited.

[0178] The improved mechanical strength achieved through the arching effect can help overcome this limitation. Sample 15 in a half-cell using Li foil as both the reference and counter electrode. C 54 V and 155 S Charging cycles at 0.5C ( Figure 5A) represents each sample type ( Figures 17A-17B This demonstrates the decisive role of nanostructures. 54 V The highest capacity was shown during the first 60 cycles, followed by 15. C Both samples showed an initial increase in capacity associated with activation. Figure 18A-18I Despite 54 V Expand 250% ( Figure 19 While its capacity retention is similar to that of the columnar structure, it exhibits higher coulombic efficiency. In contrast, 155 S Rapid capacity decay was observed, especially during the first 15 cycles, which was attributed to the loss of active material due to separation from the substrate, as confirmed by SEM. Figure 18A-18I This effect can also explain 155. S The high coulombic efficiency is 96-100% ( Figure 5B ), while sample 54 V The Coulomb efficiency record is 85-96%, 15 C The coulombic efficiency is recorded as 60-85%. For sample 54... V and 15 C Coulombic efficiency reflects the irreversible consumption of lithium during charging due to side reactions (typically the formation of the SEI), and a low value during cycling indicates that a new electrode is exposed to the electrolyte due to breakage. Therefore, 54 V The arched structure forms a seal between the electrode and the electrolyte, reducing lithium consumption in side reactions.

[0179] Electrochemical impedance spectroscopy (EIS) Figure 20A-20D ) confirmed, 15 C The resistance associated with electrode / electrolyte interface phenomena (SEI and charge transfer) is 54. V Three times higher than at that time. In fact, 54 V The sealed surface protects the surface while allowing the same fast charging / discharging as the columnar structure (charge-discharge and coulombic efficiency diagrams at 5C are shown in the figure). Figures 21A-21B (As shown). This is consistent with recent chemimechanical models that suggest high-E-value anode materials can withstand higher lithiation stresses before buckling.

[0180] Because the arched structure is generated by TaNS, it can be assembled independently of the substrate. This was demonstrated when a second TaNS layer was deposited on top of an existing Si arched structure before Si was deposited. The second TaNS layer prevented the columnar deposited structures from merging; instead, it generated a second arched structure. Figures 21A-21B (Refer to double D54) V The layer is represented as D54 V D54 VThe samples also confirmed a non-uniform E distribution, with values ​​observed in a single layer falling within the same range. Figures 23A-23B ).

[0181] To eliminate the film thickness effect, sample D54 V The electrochemical performance is comparable to that of deposited sample 110 containing the same amount of Si. S (i.e., having a single TaNS layer) comparison ( Figures 5C-5D D54 V The initial capacity was 3230 mAh g⁻¹, and after an increase of approximately 5% due to activation during the first cycle, the capacity retention rate after 100 cycles was 88% (2832 mAh g⁻¹). In comparison, 110 S Strong activation was observed in the sample, reaching a maximum capacity of 2700 mAh g⁻¹ after 20 cycles, which decreased by 45% (1477 mAh g⁻¹) after 100 cycles. Compared to a monolayer 54V, D54… V Improved electrochemical performance was also shown, with similar capacity during the first 50 cycles, but with higher capacity retention and coulombic efficiency, values ​​between 90% and 98%. Figures 24A-24B The double-layered construction significantly enhances the mechanical stability of the electrode, which retains this structure after charge-discharge cycles. Figure 25 ).

[0182] The electrochemical response of the studied electrodes is closely related to their mechanical and structural properties. The monolayer arched structure exhibits the highest E value, due to the arching effect's ability to transfer compressive stress to the pillars. This dissipates stress generated during lithiation, preventing film cracking that could damage the deposited structure. It also seals the electrode, significantly reducing side reactions and SEI formation experienced by the pillared structure. After 20 cycles, capacity decay is observed, with a maximum coulombic efficiency of 95%. This may be attributed to the free expansion space in the vertical direction, although a clamping effect exists in the transverse direction of the film, which could lead to long-term mechanical failure. However, repeating the arched structure introduces a new clamping effect in the vertical direction, improving capacity retention and coulombic efficiency, thereby improving overall mechanical stability.

[0183] <7. Conclusion>

[0184] For the first time, an arched structure with a final arching effect has been introduced at the nanoscale. This structure demonstrates the possibility of novel Si anode designs for LIBs, but is also applicable to other materials and applications where surface mechanics plays a crucial role. An arching effect is observed during columnar growth, when the columns contact each other, sealing the anode within the arched structure; this facilitates stress dissipation, prevents Si electrode cracking during cycling, and effectively reduces capacity decay. Compared to columnar arrangements, SEI formation is significantly reduced, minimizing lithium consumption and improving coulombic efficiency, while retaining the advantages of columnar structures, such as the high charge / discharge rate of the battery. When this nanostructure unit repeats along the vertical axis, the material achieves surface stability, effectively releasing applied stress. This is observed in the construction of an improved-sealed bilayer aqueduct-like arched structure, resulting in higher coulombic efficiency and mechanical stability, indicating an enhanced arching effect. Most importantly, the design of this novel nanoarchitecture provides ample room for further optimization, for example, by using different deposition techniques for high-end production or by changing the nanoparticle scaffold material.

[0185] Nanoarchitectural units, known as nanoarches, are grown using scalable physical methods.

[0186] The nanoarched structure is formed in a columnar membrane with optimized features (composed of columns that contact each other at the top, forming an arch);

[0187] The presence of numerous nanopores and sealed surfaces results in materials with high mechanical stability for use in membranes under strong and variable stress.

[0188] Nanoarched structural units are grown using nanoparticles as a scaffold, enabling the composite to be longitudinally repeated in multiple layers, thereby enhancing the optimized properties observed in monolayers.

[0189] Nanoarch structures were tested in the Si film of the Li-ion battery anode, demonstrating high coulombic efficiency, fast charge-discharge response, and improved cycle performance.

[0190] <8. Experimental Section>

[0191] <8-1. Sample Preparation>

[0192] All samples were deposited using a vapor deposition system (Mantis Deposition Ltd) in a high vacuum (2.0 × 10⁻⁶) environment. -8 Preparation was carried out at a temperature of 1 mbar and supported by a rotating support (all depositions were performed at 2 rpm) to obtain uniform film deposition. For Ta nanoparticle deposition, an Ar gas flow of 60 standard cubic centimeters per minute, a DC magnetron power of 45 W, and a collection region length of 100 mm were selected. A 110 W RF sputtering source with a 2.1 × 10⁻⁶ mbar sputtering depth was used. -3Si thin films were deposited under millibar Ar pressure. Magnetron sputtering targets of silicon (n-type, purity >99.999%, resistivity <0.001 W / m) and tantalum (>99.95% purity) were sourced from Kurt J. Lesker. All depositions were performed at ambient temperature (~298 K, measured by a substrate holder thermocouple) without any external bias applied to the substrate. Finally, at 8 × 10⁻⁶... -3 All anodes were annealed at 150°C for 60 minutes under a pressure of millibars of Ar.

[0193] <8-2. FIB-SEM and TEM Thin Section Characterization>

[0194] Using a FEI Helios G3 UC FIB-SEM, cross-sections and sample surfaces were imaged via focused ion beam (FIB) milling combined with SEM. The same FIB-SEM system, equipped with Pt deposition needles and OMNIPROBE™ extraction needles, was used to prepare TEM slices. They were prepared using a conventional “H-bar” technique, by depositing a thin Pt film in situ to cut two grooves in the sample to protect the target surface area during milling. The slices were then thinned from the sample milling to approximately 40 nm to allow the TEM beam to pass through. Using the extraction needles, the slices were then fed onto the top of a TEM half-grid, where they were bonded to the Pt deposition needles. The TEM slices were imaged using a FEI Titan Environmental TEM equipped with a spherical aberration image corrector at an operating voltage of 300 kV.

[0195] <8-3. PF-QNM Measurement>

[0196] The surface morphology and elastic modulus of the Si samples were measured using an AFM (Multimode 8, Bruker) operated in Peak Force tapping mode. Sample imaging and PF-QNM™ measurements were performed using a Bruker ultra-high force cantilever (DNISP-HS) with a diamond tip (~71.5 kHz resonant frequency, 432 N / m spring constant, and ~40 nm nominal tip radius). A standard relative method was used for E measurements with fused silica (nominal E: ~72 GPa) as the reference sample. This method first calibrated the cantilever deflection sensitivity of the hard sapphire sample by fitting the linear portion of the force-distance curve in ramp mode. The spring constant value during measurement was set to 432 N / m according to the manufacturer's calibration table. PF-QNM measurements were then performed with the reference sample (fused silica) loaded, and the peak force setpoint was adjusted to obtain the desired deformation (1-2 nm). Subsequently, the tip radius parameter was varied so that the measured elastic modulus of the reference sample was its precise value (72 GPa). After calibrating the tip radius using a reference sample, PF-QNM measurements were performed on the TaSi samples, and the peak force setpoint was adjusted to match the deformation of the reference sample. AFM images (512×512 pixels) were captured at a scan rate of 0.5 Hz and analyzed using Nanoscope Analysis (Ver.9) software. Although no reduction processing was applied to the modulus mapping images or data, it was a quantitative property measurement performed using the standard relative method. Tip cleaning was performed using indentations on a gold surface, followed by individual tip calibration for each sample.

[0197] For the PF-QNM, the z-piezoelectric sensor taps the sample surface and measures the force-distance curve for each imaging pixel. Based on the force-distance curve, E is determined by fitting the DMT model to the portion of the force-distance curve where the sample and tip contact, using the following formula:

[0198] [Mathematical Expression 4]

[0199]

[0200] Among them, F tip , R, d, F adh and k are the applied force, tip radius, deformation, adhesion force, and cantilever spring constant, respectively.

[0201] Reduced modulus (E) r The modulus (E) of the sample is related as follows:

[0202] [Mathematical Expression 5]

[0203]

[0204] Where E iand v i Here, E represents the Young's modulus and Poisson's ratio at the AFM tip, and v is the Poisson's ratio of the sample. The contribution of the second term in Equation 2 can be neglected because E i >>E.

[0205] <8-4. Electrochemical Characterization>

[0206] For electrochemical characterization, samples were prepared on copper foil (0.25 mm thick, Puratronic 99.9985%, Alfa Aesar). Electrochemical characterization was performed using a dual-electrode Swagelok cell with lithium foil as both the reference and counter electrode. Ethylene carbonate (EC, >99%), diethyl carbonate (DEC, >99%), and lithium hexafluorophosphate (LiPF6, >99.99%) used as electrolytes were purchased from Sigma-Aldrich, while lithium foil (0.38 mm thick, 99.9%) and Celgard (25 mm thick) from MTI were used as separators. The electrolyte solution was 1.0 M LiPF6 in a 50:50 (w / w) mixture of EC and DEC. All cells were assembled in an Ar glove box (UNICO) with O2 and humidity below 0.25 ppm. Charge-discharge measurements were performed using two 8-channel battery analyzers (0.005–1 mA and 0.02–10 mA, up to 5 V, MTI Corp.) within a voltage window of 0.01–1 V. To calculate the charge-discharge rate, 1C was defined as 3579 mAh g⁻¹. -1 After three cycles at 0.5C, the half-cell was opened in an Ar glove box, the anode was flushed three times with dimethyl carbonate (DMC, >99%), and then subjected to high vacuum (1.0 × 10⁻⁶). -6 Dry at 1000 mbar for at least 12 hours. Before introducing the sample into the FIB-SEM, remove it and scrape it with a diamond pen.

[0207] <8-5. Calculation Method>

[0208] We conducted two sets of MD simulations (i) to elucidate the formation mechanism of the arch structure, and (ii) to explain the changes in the mechanical properties of the structure at different growth stages.

[0209] In the first group, we simulated the deposition of silicon layers with and without nanoparticle scaffolds. Initially, an amorphous Si substrate was prepared in an isothermal-isobaric ensemble at 0 bar via a rapid heating (3000 K, 100 ps)-quenching (500 K, 100 ps) process. The thermally treated simulated cell initially had dimensions of 109 × 109 × 55 Å. Next, we opened the top surface, fixed an atomic layer within 6 Å at the bottom, and performed an additional 50 ps relaxation in a canonical ensemble. For the structure with a nanoparticle scaffold, the nanoparticles naturally deposited on the amorphous silicon substrate. We placed diamond-lattice silicon nanoparticles with a diameter of 5 nm 15 Å above the surface at the (0,0) lateral position.

[0210] Silicon nanoparticles were heat-treated at 500 K for 50 ps, ​​then given an additional velocity of 20 m / s to land on the substrate, and relaxed on the substrate for another 50 ps. Thin film growth was simulated by adding a new Si atom from the top of the cell every 200 MD steps; a total of 215,563 Si atoms were added (average deposition rate of 1.1 nm / ns). To simulate the rotating substrate of the experimental setup, the initial velocity of the deposited atoms was set to rotate at a rate of 1 round / ns in 20 ps steps. The incident angle was 30° to the surface, and the total velocity was 1000 m / s. No velocity scaling was applied to undeposited atoms. The temperature of the deposited atoms (except those fixed at the bottom) was controlled by applying a Langevin thermostat to a group of deposited atoms located 1 nm below the opening surface. This group was updated every 2.8 ns, so the atoms deposited during this period were scaled after the update. The simulation lasted approximately 40 ns with a time step of 1 fs. We also used different nanoparticles and battery sizes and temperatures, or used two nanoparticles, to perform benchmark simulations explicitly following the same procedure described above.

[0211] The second set of simulations involved mechanical measurements using a simulated AFM tip; different thicknesses of deposited structures were selected (deposition times of 5, 10, ..., 40 ns after deposition) and relaxed at 500 K for 200 ps. Subsequently, a flat diamond carbon plate with a thickness of 5 angstroms was placed 5 angstroms above the surface. Simulations were performed for each AFM measurement until the loading depth reached approximately 3.5 nm (0.01 nm / ps for 400 ps), then held at a fixed position on the tip for 600 ps. Finally, the tip retracted for 400 ps at a rate of 0.002 nm / ps. The evolution of the feedback force was recorded.

[0212] All simulations were performed using the classic MD code LAMMPS, and the results were visualized using OVITO. We used the environment-dependent interatomic potential (EDIP) parameterized for silicon. When testing bulk, defects, and phase transitions, EDIP significantly outperforms other existing potentials for silicon, including the popular Stillinger-Weber and Tersoff potentials. EDIP has been used to study liquid-amorphous transitions, self-diffusion, crystal plasticity, brittle fracture, solid-state epitaxial growth, and amorphous structures. For the C-Si interaction in the purely repulsive Ziegler-Biersack-Littmark (ZBL) potential, non-viscous feedback force curves were used.

Claims

1. A composite nanostructure unit, comprising: A columnar film is grown on top of another layer, wherein the columns contact each other at the top to form an arch with optimized properties, and wherein the columnar film is grown on top of a layer of metal nanoparticles. The columnar film is an amorphous Si film in an annealed state. The metal nanoparticles are Ta nanoparticles.

2. A multilayer composite comprising at least two longitudinal repetitions of the composite nanostructure unit of claim 1.

3. A method for manufacturing a composite nanostructure unit, the method comprising the following steps: a) Deposition of nanoparticles onto a substrate from the vapor phase; and b) Growing a columnar film on the layer of nanoparticles, The column diameter of the columnar membrane increases with thickness until the tops of the columns contact each other, thereby sealing the surface by forming an arched structure in step b). It further includes the following steps: c) Heat-anneal the columnar film. The columnar film is an amorphous Si film. The nanoparticles are metallic nanoparticles. The metal nanoparticles are Ta nanoparticles.

4. The manufacturing method according to claim 3, In step b), the growth of the columnar membrane is stopped as soon as possible after the arch is formed.

Images