ELECTRODE COMPOSITE

Abstract

A single-electrode lithium-ion battery component includes a current collector and a silicon-based active layer. The active layer comprises a polyacrylonitrile lattice structure with continuous carbon domains. Silicon particles are distributed within the vacancies of the polyacrylonitrile lattice, which is configured to enclose the silicon particles during the volume expansion and contraction that occur during charging cycles.

Description

AREA OF TECHNOLOGY

[0001] This disclosure concerns electrode materials for lithium-ion batteries. GENERAL STATE OF THE ART

[0002] Silicon can be used as an anode material in batteries, including solid-state batteries, due to its high lithium storage capacity and low operating potential. Despite these advantages, silicon anodes face challenges to market maturity, primarily due to the material's brittleness. The volume expansion silicon undergoes during lithium-ion absorption induces mechanical stress, leading to pulverization. This repeated expansion and contraction during charge / discharge cycles can result in poor capacity retention and reduced lifetime. Pulverized silicon particles can disrupt the electrode-electrolyte interface and contribute to the formation of a solid electrolyte interphase layer. SUMMARY

[0003] A lithium-ion battery component comprises an electrode with a current collector and an adhering silicon-based active layer containing a polyacrylonitrile lattice. Continuous carbon domains and silicon particles are distributed within vacancies of the polyacrylonitrile lattice, which is configured to trap the silicon particles during the volume expansion and contraction of the electrode during charging cycles. The silicon particles can constitute between 30 and 70 percent by weight of the silicon-based active layer. The silicon particles can have a size ranging from 30 nanometers to 150 nanometers. The polyacrylonitrile lattice can have micropores with a size range of 1 nanometer to 200 nanometers. The continuous carbon domains can consist of a mixture of cyclized carbon and graphitized carbon.The silicon-based active layer can maintain a capacity of at least 80% after 100 charge / discharge cycles.

[0004] A solid-state battery can include a current collector, a separator, and a pair of electrodes surrounding the separator, with at least one of the electrodes comprising a silicon-based active layer containing silicon particles encapsulated and conductively interconnected by continuous carbon chains of a polyacrylonitrile composite configured to maintain conductive contact between the silicon particles during electrode charging cycles. The silicon particles can constitute between 30 and 70 percent by weight of the silicon-based active layer. The silicon particles can have a size ranging from 30 nanometers to 150 nanometers. The polyacrylonitrile composite can have micropores with a size range of 1 nanometer to 200 nanometers. The continuous carbon chains can be a mixture of cyclized carbon and graphitized carbon.The silicon-based active layer can maintain a capacity of at least 80% after 100 charge / discharge cycles. The polyacrylonitrile lattice can exhibit a hierarchical porous structure containing macropores, mesopores, and micropores. The polyacrylonitrile composite can have an electrical conductivity between 1 S / cm and 1000 S / cm. The continuous carbon domains can form a three-dimensional, interconnected network across the entire polyacrylonitrile lattice.

[0005] A method for forming an electrode active material involves heating a precursor solution of a nitrile monomer and silicon nanoparticles to form a silicon polymer gel consisting of silicon nanoparticles dispersed within a polymer matrix, lyophilizing the silicon polymer gel to create a porous silicon polymer structure, oxidizing the porous silicon polymer structure to form an oxidized porous silicon polymer structure, and carbonizing the oxidized porous silicon polymer structure to form an electrode active material. The method can include controlling the carbonization process to produce an electrode active material in which silicon nanoparticles comprise between 30 and 70 percent by weight of the electrode active material. The silicon nanoparticles can have a size ranging from 30 nanometers to 150 nanometers.The porous silicon polymer structure can contain micropores in a size range of 1 nanometer to 200 nanometers. The carbonization step can be carried out at a temperature between 300 °C and 1000 °C to produce continuous carbon domains comprising a mixture of cyclized carbon and graphitized carbon. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic representation of a process for forming a negative electrode; Fig. Figure 2 shows images of microstructures in the process of forming the negative electrode of the Fig. 1; Fig. Figure 3 is a schematic representation of a battery cell; Fig. 4 is a flowchart of a process for forming an electrode; Fig. Figure 5 is a graph of voltage versus capacitance for a half-cell containing the disclosed negative electrode material; Fig. Figure 6 is a graph of differential capacitance versus voltage for a half-cell containing the disclosed negative electrode material; Fig. Figure 7 is a graph of the cell's internal resistance over cycles; Fig. Figure 8 is a graph of cycle performance; Fig. Figure 9 is a table showing percentage results of specific capacity and capacity maintenance for different tests; Fig. Figure 10 is a graph of capacity conservation versus rate; and Fig. Figures 11-12 are graphs of a galvanostatic charge / discharge cycle with different charge rates. DETAILED DESCRIPTION

[0006] According to this disclosure, detailed embodiments of electrode structures, manufacturing processes, and battery systems are disclosed herein. These embodiments are representative of an approach to increasing the performance of a lithium-ion battery. The figures and descriptions provided are for illustrative purposes only and may not represent all possible variations or configurations. Certain features may be enlarged or reduced in size to highlight specific aspects of the electrode assemblies and their formation processes. Thus, the disclosed specific structural and functional details are not intended to limit the scope of the invention but rather to provide a fundamental basis for the person skilled in the art to implement various embodiments of the claimed subject matter.

[0007] Unless expressly stated otherwise, all numerical values, measurements, percentages, weights, and similar quantities enumerated in the claims are to be understood as being preceded by the term "approximately." This convention applies even if the term "approximately" is not explicitly used. The intention is to include variations resulting from standard measurement techniques, manufacturing processes, material properties, and the inherent variability in the performance of the electrode structures and battery systems as defined by the claims.For example, if reference is made to a silicon particle size in the range of "30 nanometers to 150 nanometers" or a carbonization temperature range of "300 °C to 1000 °C", such values ​​should be interpreted as "approximately" the specified range, whereby deviations are possible which do not substantially change the functionality or performance of the claimed invention.

[0008] The disclosure addresses challenges in the development of high-performance lithium-ion and solid-state batteries by introducing a silicon-based composite material that enhances the stability and efficiency of battery electrodes. The disclosed material utilizes a composite of silicon (Si) nanoparticles and a polyacrylonitrile (PAN)-derived carbon matrix with a robust structure capable of mitigating the volume expansion of silicon during charge cycles.

[0009] A silicon-based active layer within an electrode is characterized by a PAN lattice with continuous carbon domains. These carbon domains are formed by heat-treating the PAN at temperatures ranging from 300 °C to 1000 °C to achieve varying degrees of carbonization, from cyclized carbon to fully graphitized carbon, depending on the specific processing conditions. Silicon nanoparticles, ranging in size from 30 to 150 nanometers (nm), are located within the vacancies of the carbon lattice. This configuration effectively encapsulates the silicon particles, minimizing their volumetric expansion and contraction during electrochemical charge and discharge cycles. By enclosing the silicon within the carbon matrix, the structural integrity of the electrode is maintained, which in turn enhances the overall cycle stability of the battery.

[0010] In the context of lithium-ion battery applications, this silicon-based active layer can be integrated into a current collector, providing high capacity due to the presence of silicon while simultaneously benefiting from the mechanical support and electronic conductivity provided by the carbon matrix. The silicon content in the active layer can be adjusted to balance capacity with stability and can range from 30 to 70 wt%.

[0011] By controlling the Si content and the nanoparticle size distribution, an effective balance between high energy density and long-term cycle performance is achieved.

[0012] For solid-state battery configurations, this disclosure utilizes the same Si-PAN composite. The continuous carbon domains within the composite act as conductive chains that connect the Si particles, thereby maintaining this electrical conductivity across the entire electrode, even when the Si undergoes volumetric changes during charge cycles. This continuous connectivity is necessary for solid-state batteries, where maintaining consistent electrical contact is challenging due to the different mechanical properties of solid electrolytes compared to liquid electrolytes.

[0013] The disclosed Si-PAN composite also incorporates a hierarchical porous structure with pore sizes ranging from 1 to 200 nm. This porosity plays a role in absorbing the mechanical stresses associated with volume changes in the Si and facilitates ion transport within the electrode, thereby increasing the charging rate capability and overall electrochemical performance of the battery.

[0014] The synthesis of this electrode material involves the formation of a silicon polymer gel, followed by processing steps configured to generate a desired porous structure and carbon domain configuration. First, silicon nanoparticles are dispersed in a PAN solution to form a homogeneous gel. This gel undergoes heat treatments to induce the formation of continuous carbon domains and the hierarchical porous structure, both of which contribute to the material's performance. The materials and processes are compatible with existing mass production manufacturing processes, making them feasible for commercial production.

[0015] The Si-PAN composite increases cycle stability by effectively enclosing the Si particles within the carbon matrix, thus minimizing the effects of volume expansion in Si. The continuous carbon domains increase the electronic conductivity within the electrode, thereby reducing internal resistance and increasing the overall cell performance. Additionally, the carbon coating surrounding the Si particles can mitigate the formation of the solid-electrolyte interface (SEI), a problem that can lead to capacity loss in conventional silicon anodes.

[0016] Fig. Figure 1 shows a synthesis process 10 for Si-PAN composites. The flowchart illustrates a step-by-step procedure for generating the composite material. The process begins with an initial mixture 12 containing nitrogen gas, acrylonitrile, azobisisobutyronitrile, dimethyl sulfoxide, and Si nanoparticles. This mixture undergoes gelation 14 by heating it at 70 °C for 24 hours, resulting in the formation of a Si-PAN gel. An enlarged circular inset shows the structure of this gel, with Si nanoparticles 16 dispersed within a polymer matrix 18. The gel then undergoes a solvent exchange and lyophilization step 20, in which the original solvent is replaced by water, followed by lyophilization to generate a nanoporous Si-PAN structure. Next, an oxidation process 22 takes place at 250 °C in air, transforming the material into an oxidized nanoporous Si-PAN structure.The final step of carbonization 24 is carried out at 1000 °C under nitrogen gas, resulting in a Si-PAN composite.

[0017] Fig. Figure 2 shows a series of images of the microstructure evolution of the Si-PAN composite during phases of the synthesis process 10. Microstructure 20' shows the morphology of the material after solvent exchange and lyophilization, exhibiting a highly porous, low-density structure in which the Si nanoparticles 16 are distributed throughout the polymer network 18. Microstructure 22' shows the changes after oxidation, including some shrinkage and darkening of the polymer network 18 with potential surface modifications of both the Si nanoparticles 16 and the polymer network 18. Microstructure 24' shows the composite after carbonization, exhibiting a denser, predominantly carbon-based framework with integrated Si nanoparticles 16. Microstructure 24' shows signs of graphitization with Si carbide formation at interfaces and a changed porosity compared to microstructures 20' and 22'.

[0018] Fig. Figure 3 shows components of a battery cell 26 in a layered configuration, with each component stacked in a specific sequence to create a functional energy storage device. The battery cell 26 includes a positive current collector 28, which can be a stainless steel cap acting as a sealed enclosure for a positive terminal. Stacked with the current collector 28 is a stainless steel spring 30, which provides pressure to maintain contact between the components and accommodate any volume changes during cycling. A stainless steel spacer 32 maintains the correct spacing and electrical contact within the battery cell 26. A positive electrode 34, positioned with the stainless steel spacer 32, can be made of a cathode material suitable for solid-state lithium-ion batteries.A separator 36, acting as a porous membrane that allows ion transfer while preventing direct contact between the electrodes, is placed between the positive electrode 34 and the negative electrode 38. The negative electrode 38 contains a Si-PAN composite active material formed by synthesis process 10 and serves as the anode in the battery cell 26. A negative current collector 40 can be an aluminum-coated can that forms an outer shell of the battery cell 26.

[0019] In an experimental setup, the battery cell 26 was constructed and tested under specific conditions. The negative electrode 38 was formed with lithium metal and 7 wt% Si-PAN composite with carbon as the active material, while the positive electrode 34 was graphite. The two electrodes 34 and 38 were loaded with a weight of 5-6 milligrams (mg) per square centimeter (cm²). 2) and a loading density of 1.5–1.6 grams (g) per cubic centimeter (ccm). Battery cell 26 uses 1 mole per liter of lithium hexafluorophosphate in a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 25 / 75 as the electrolyte. The tests were carried out with a full charge / discharge cycle of 10 hours. The results showed that the specific charge capacity of battery cell 26, measured at the positive electrode 34, increased from 403.3 milliampere-hours (mAh) per g in the first cycle to 419.7 mAh / g in the third cycle, while the discharge capacity started higher at 454 mAh / g and stabilized at 425.9 mAh / g by the third cycle. The Coulomb efficiency improved from 88.84% in the first cycle to 98.54% in the third cycle, suggesting a rapid stabilization of the initial irreversible processes. The cell operates between approximately 0 volts (V) and 2.5 V relative to Li / Li. +The galvanostatic charge-discharge (GCD) curves show a plateau region around 0.2–0.1 V during discharge, which is characteristic of lithium extraction from silicon-based anodes. Cycle stability was demonstrated by similar GCD profiles for cycles 2 and 3 and overlapping charge curves for all three cycles. Some initial irreversible capacity loss was observed in the first cycle, but this decreased in subsequent cycles. Overall, the high specific capacity (over 400 mAh / g) exceeds that of conventional graphite anodes, and the rapid stabilization of the Coulomb efficiency suggests good reversibility of electrochemical processes.

[0020] Fig. Figure 4 is a flowchart of a process for forming an electrode active material 42. The process begins with step 44, in which a precursor solution containing a nitrile monomer and silicon nanoparticles is heated to form a silicon polymer gel. In this gel, silicon nanoparticles are dispersed within a polymer matrix. The second step 46 involves lyophilizing the silicon polymer gel produced in step 44. This lyophilization process creates a porous silicon polymer structure, which influences the performance characteristics of the final material. Following lyophilization, the third step 48 involves oxidizing the porous silicon polymer structure formed in step 46. This oxidation process results in an oxidized porous silicon polymer structure, further modifying the material's properties.The final step 50 involves carbonizing the oxidized porous silicon polymer structure produced in step 48 to form a finished Si-PAN electrode active material.

[0021] The silicon nanoparticles used in the initial precursor solution typically have a size range of 30 to 150 nm. The porous structure generated during lyophilization contains micropores in the size range of 1 to 200 nm, which contributes to the electrochemical performance of the material. Carbonization step 50 can be carried out at temperatures between 300 °C and 1000 °C. This temperature range allows the formation of continuous carbon domains containing a mixture of cyclized and graphitized carbon. The resulting Si-PAN electrode active material contains silicon nanoparticles comprising between 30 and 70 wt% of the total material.

[0022] Fig. Figures 5-6 show the electrochemical performance of a Si-PAN composite electrode material in a lithium half-cell configuration with a solid electrolyte. These tests were performed using an anode composition of 66:28:2:4 wt% Si-PAN:solid electrolyte:carbon black:binder with an areal capacity of 3 mAh / cm². 2 The tests were carried out. The voltage range was set to 0.05–1.0 V and the tests were performed at a temperature of 45 °C. The Si-PAN composite used had a Si-to-carbon ratio of 55:45. Fig. Figure 5 shows voltage profiles for two consecutive charge / discharge cycles, while Fig. Figure 6 shows the corresponding diagrams of the differential capacity (dQ / dV).

[0023] In Fig. Figure 5 shows the high capacity of the Si / PAN composite, reaching approximately 2500–3000 mAh / g. This capacity significantly exceeds that of conventional graphite anodes (theoretical capacity ~372 mAh / g) and approaches the theoretical capacity of silicon at 4200 mAh / g. The charging curves show a gradual increase in voltage with capacity, while the discharging curves exhibit a more stable voltage plateau, characteristic of silicon-based anodes during lithiation and delthiation processes. A marked difference between the first and second cycles, particularly in the low-capacity region of the discharge curve, suggests an initial irreversible capacity loss, which may be due to SEI formation.

[0024] Fig. Figure 6 shows the electrochemical reactions occurring during the cycles. Sharp peaks in the negative region (around 0.1 V) during the first cycle indicate primary lithiation reactions of Si. These peaks become less pronounced in the second cycle, suggesting structural changes following the initial lithiation. The broader peaks in the positive region (0.3–0.5 V) represent the lithiation process, with multiple peaks possibly indicating different phases of lithium extraction from the silicon structure. The differences between the first and second cycles are more pronounced in this differential capacitance graph, particularly in the lithiation region, further confirming the initial irreversible changes of the electrode.

[0025] The relatively stable performance over two cycles, particularly in the higher voltage ranges, suggests that the Si-PAN composite structure effectively mitigates problems associated with Si anodes, such as pulverization and capacitance degradation. This stability can be attributed to the microporous structure (pores of 1–200 nm) of the Si-PAN composite, which helps to accommodate the volume expansion of silicon domains during charging. Additionally, the continuous carbon domains resulting from PAN pyrolysis contribute to increased electron conductivity and lower internal resistance within the electrode, as demonstrated by the smooth voltage profiles shown in Fig. 5 can be observed.

[0026] Fig. Figures 7-8 show the performance characteristics of the Si-PAN composite anode material over 60 charge / discharge cycles with a charge rate (C) of 0.2. Fig. Figure 7 illustrates the evolution of the cell's internal resistance when comparing a standard anode material "Ch" and a Si-PAN composite "DCIR_Si / PAN". The "Ch" series remains relatively constant at approximately 20 ohms throughout the cycles, indicating a stable resistance during charging. In contrast, the "DCIR_Si / PAN" series shows a gradual increase from approximately 20 ohms to 140 ohms over the 60 cycles, suggesting a progressive increase in the cell's internal resistance. This increase can be attributed to factors such as SEI layer growth or structural changes in the electrode during the cycles.

[0027] Fig. Figure 8 shows the cycle performance, with specific capacity and coulomb efficiency plotted over the same 60 cycles. The Si-PAN anode exhibits an initially high specific capacity of approximately 3000 mAh / g, which quickly stabilizes at around 2000 mAh / g after the first few cycles. The discharge and charge capacities follow each other closely, indicating reversibility of the lithiation / delithiation processes. The anode material shows high capacity retention, with a minimal decrease observed over the 60 cycles. The coulomb efficiency quickly reaches and maintains values ​​close to 100%, further confirming the high reversibility of the electrochemical reactions. A slight increase in capacity is observed around cycle 60, which may be due to the activation of previously inactive material or measurement fluctuations.

[0028] Fig. 9 and Fig. Figure 10 shows the rate capability of the Si-PAN composite anode material with specific capacity and capacity retention at different charging and discharging rates. Fig. Figure 9 shows a tabular overview of the electrode's performance under different test conditions. Fig. Section 9 includes a 10-hour charge (C / 10) compared to a discharge and charge at various C-rates. For each test condition, the C-rate, specific discharge capacity (SpeCapD), specific charge capacity (SpeCapC), and capacity retention percentage are provided. The C / 10 test shows the highest specific capacities of 429.20 mAh / g for discharge and 433.00 mAh / g for charge, which serves as the basis for 100% capacity retention. The discharge capacity changes with increasing C-rates from C / 2 to 2.0C. Even at 2.0C, the electrode retains 92.61% of its capacity, indicating high rate efficiency during discharge. The specific charge capacity rate is significantly affected by increasing the C-rates. At C / 2, capacity maintenance drops to 36.88% and at 2.0C it falls further to only 3.26% of the base capacity.

[0029] Fig. Figure 10 is a bar graph illustrating the relationship between capacity retention and various charge / discharge rates. The graph shows that capacity retention remains high (near 100%) for discharge rates up to 2.0C, decreasing only slightly as the discharge rate increases. However, there is a drop in capacity retention for charge rates, particularly when increasing from 0.5C to 2.0C. The 0.5C charge rate shows a retention of approximately 40%, which drops to about 15% for 1.0C and further decreases to below 10% for charge rates of 1.5C and 2.0C. This graph suggests that the battery cell incorporating the Si-PAN composite performs well across a range of discharge rates.

[0030] Fig. 11 and Fig. Figure 12 shows GCD curves for the Si-PAN composite anode material at different rates. Fig. Figure 10 shows the GCD curves for discharge rates in a range of 0.1C to 2.0C, where the x-axis represents the specific capacity in mAh / g and the y-axis the potential in volts relative to Li / Li + The discharge curve shows the highest specific capacity at the lowest rate (0.1C), reaching almost 450 mAh / g. As the discharge rate increases, the curves shift to lower specific capacities, with the lowest capacity at 2.0C. All curves maintain a similar shape, exhibiting a steep initial drop followed by a slower rise and ending with another steep drop. The potential plateau of approximately 0.2–0.3 V becomes less pronounced at higher rates, indicating increased polarization.

[0031] Fig.Figure 12 shows GCD curves for charging rates, also ranging from 0.1C to 2.0C. The 0.1C charging curve achieves the highest specific capacity, similar to the discharge process. However, with increasing charging rate, there is a dramatic reduction in the achievable specific capacity. Curves at higher rates (1.0C to 2.0C) show limited capacity with steep potential increases. The 0.1C and 0.5C curves show a slower slope and higher capacities compared to faster rates, with a visible potential plateau at approximately 0.3–0.4 V for lower rates, which becomes less pronounced at higher rates.

[0032] An analysis of the silicon content and pore properties in the composite material shows a trend toward larger pore sizes, particularly in the mesoporous region, with increasing silicon content. This shift suggests that higher silicon incorporation leads to the development of a more open porous structure. These structural changes with increasing silicon content affect the material's performance as an anode in lithium-ion batteries. The higher silicon content provides greater theoretical capacity, while the mesoporous structure can accommodate the volume changes associated with silicon lithiation and delithiation. However, the trade-off regarding surface area may negatively impact the electrode-electrolyte interface and rate capability.

[0033] While the specific embodiments of the electrode structures, the methods for forming such structures, and the resulting battery systems have been described in detail, these embodiments are not exhaustive for all possible configurations. The language used in this description is for descriptive purposes and is not intended to limit the scope of the invention. Modifications and variations may occur without departing from the core concepts of the invention described herein. Furthermore, the features and elements of different disclosed embodiments may be combined in novel ways to form additional embodiments within the scope of the claimed subject matter, even if such combinations are not expressly described in this description.

[0034] According to the present invention, a lithium-ion battery component is provided comprising: an electrode with a current collector and a silicon-based active layer adhering thereto, which includes a polyacrylonitrile grid, wherein continuous carbon domains and silicon particles are distributed within vacancies of the polyacrylonitrile grid, which is configured to enclose the silicon particles during the volume expansion and contraction of the electrode during charging cycles.

[0035] According to one embodiment, the silicon particles make up between 30 and 70 percent by weight of the silicon-based active layer.

[0036] According to one embodiment, the silicon particles have a size in the range of 30 nanometers to 150 nanometers.

[0037] According to one embodiment, the polyacrylonitrile grid has micropores in a size range from 1 nanometer to 200 nanometers.

[0038] According to one embodiment, the continuous carbon domains are a mixture of cyclized carbon and graphitized carbon.

[0039] According to one embodiment, the silicon-based active layer maintains a capacity of at least 80% after 100 charge / discharge cycles.

[0040] According to the present invention, a solid-state battery is provided comprising: a current collector; a separator; and a pair of electrodes surrounding the separator, wherein at least one of the electrodes includes a silicon-based active layer with silicon particles encapsulated and conductively interconnected by continuous carbon chains of a polyacrylonitrile composite, configured to maintain conductive contact between the silicon particles during electrode charging cycles.

[0041] According to one embodiment, the silicon particles make up between 30 and 70 percent by weight of the silicon-based active layer.

[0042] According to one embodiment, the silicon particles have a size in the range of 30 nanometers to 150 nanometers.

[0043] According to one embodiment, the polyacrylonitrile composite material has micropores in a size range of 1 nanometer to 200 nanometers.

[0044] According to one embodiment, the continuous carbon chains are a mixture of cyclized carbon and graphitized carbon.

[0045] According to one embodiment, the silicon-based active layer maintains a capacity of at least 80% after 100 charge / discharge cycles.

[0046] According to one embodiment, the polyacrylonitrile composite material has a hierarchical porous structure comprising macropores, mesopores and micropores.

[0047] According to one embodiment, the polyacrylonitrile composite material has an electrical conductivity between 1 S / cm and 1000 S / cm.

[0048] According to one embodiment, the continuous carbon chains form a three-dimensional, interconnected network over the entire polyacrylonitrile composite.

[0049] According to the present invention, a method for forming an electrode active material comprises: heating a precursor solution of a nitrile monomer and silicon nanoparticles to form a silicon polymer gel of silicon nanoparticles dispersed within a polymer matrix; lyophilizing the silicon polymer gel to generate a porous silicon polymer structure; oxidizing the porous silicon polymer structure to form an oxidized porous silicon polymer structure; and carbonizing the oxidized porous silicon polymer structure to form an electrode active material.

[0050] In one aspect of the invention, the method involves controlling the carbonization to produce the electrode active material, wherein the silicon nanoparticles comprise between 30 and 70 percent by weight of the electrode active material.

[0051] In one aspect of the invention, the silicon nanoparticles have a size in the range of 30 nanometers to 150 nanometers.

[0052] In one aspect of the invention, the porous silicon polymer structure has micropores in a size range of 1 nanometer to 200 nanometers.

[0053] In one aspect of the invention, carbonization is carried out at a temperature between 300 °C and 1000 °C to produce continuous carbon domains comprising a mixture of cyclized carbon and graphitized carbon.

Claims

[1] Lithium-ion battery component, comprising: an electrode with a current collector and an adhering silicon-based active layer comprising a polyacrylonitrile grid, wherein continuous carbon domains and silicon particles are distributed within vacancies of the polyacrylonitrile grid, which is configured to enclose the silicon particles during volume expansion and contraction of the electrode during charging cycles. [2] Lithium-ion battery component according to claim 1, wherein the silicon particles constitute between 30 and 70 percent by weight of the silicon-based active layer. [3] Lithium-ion battery component according to claim 1, wherein the silicon particles have a size in the range of 30 nanometers to 150 nanometers. [4] Lithium-ion battery component according to claim 1, wherein the polyacrylonitrile grid has micropores in a size range of 1 nanometer to 200 nanometers. [5] Lithium-ion battery component according to claim 1, wherein the continuous carbon domains are a mixture of cyclized carbon and graphitized carbon. [6] Lithium-ion battery component according to claim 1, wherein the silicon-based active layer has a capacity retention of at least 80% after 100 charge / discharge cycles. [7] Solid-state battery, comprising: a power collector; a separator; and a pair of electrodes surrounding the separator, wherein at least one of the electrodes includes a silicon-based active layer with silicon particles encapsulated and conductively interconnected by continuous carbon chains of a polyacrylonitrile composite, configured to maintain conductive contact between the silicon particles during electrode charging cycles. [8] Solid-state battery according to claim 7, wherein the silicon particles constitute between 30 and 70 percent by weight of the silicon-based active layer. [9] Solid-state battery according to claim 7, wherein the silicon particles have a size in the range of 30 nanometers to 150 nanometers. [10] Solid-state battery according to claim 7, wherein the polyacrylonitrile composite material has micropores in a size range of 1 nanometer to 200 nanometers. [11] Solid-state battery according to claim 7, wherein the continuous carbon chains are a mixture of cyclized carbon and graphitized carbon. [12] Solid-state battery according to claim 7, wherein the silicon-based active layer has a capacity retention of at least 80% after 100 charge / discharge cycles. [13] Solid-state battery according to claim 7, wherein the polyacrylonitrile composite material has a hierarchical porous structure comprising macropores, mesopores and micropores. [14] Solid-state battery according to claim 7, wherein the continuous carbon chains form a three-dimensional, interconnected network over the entire polyacrylonitrile composite. [15] Method for forming an electrode active material, comprising: Heating a precursor solution of a nitrile monomer and silicon nanoparticles to form a silicon polymer gel consisting of silicon nanoparticles dispersed within a polymer matrix; Lyophilizing the silicon polymer gel to create a porous silicon polymer structure; Oxidizing the porous silicon polymer structure to form an oxidized porous silicon polymer structure; and Carbonizing the oxidized porous silicon polymer structure to form an electrode active material.

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