Silicon-carbon electrode material
By adopting a fiberized silicon-carbon necklace structure in the silicon anode, the crushing problem caused by the volume expansion of the silicon anode is solved, the electronic conductivity and mechanical stability are improved, and the performance of the solid-state battery is enhanced.
Patent Information
- Application Number
- CN202510331754.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-03-26
- Filing Date
- 2025-03-20
- Publication Date
- 2025-10-03
AI Technical Summary
The volume expansion of the silicon anode during charging causes it to pulverize, affecting the electron and ion conduction paths and leading to performance degradation. The low electronic conductivity of silicon particles also limits the application of solid-state batteries.
A fiberized silicon-carbon necklace structure is adopted, in which coated silicon beads are connected by carbon chains to form a conductive silicon-carbon necklace, which provides mechanical support and constrains the silicon beads during volume expansion, improving electronic transport and mechanical integrity.
The cycling stability and conductivity of the silicon anode are enhanced, the formation of the solid electrolyte interface layer is reduced, and the overall performance of the battery is improved.
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Figure CN120749205A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to electrode materials for lithium-ion batteries. Background Art
[0002] Silicon has emerged as a promising candidate for high-capacity anode materials in solid-state batteries due to its high theoretical lithium storage capacity of 4200 mAh / g, low potential of approximately 0.3 V compared to Li+ / Li, and natural abundance. However, despite these attractive attributes, widespread commercialization of silicon anodes, especially those with high silicon content (above 40 wt%), has been hampered by several challenges. One of the main obstacles is the volume expansion that silicon undergoes upon charging. This expansion, as a result of phase transitions and changes in lattice volume, often leads to the fracturing of silicon particles, a phenomenon known as pulverization. Pulverization is responsible for various performance degradation mechanisms in silicon anodes, such as loss of electronic and ionic conduction paths, electrode delamination, formation of cracks and voids, and continuous reformation of the solid electrolyte interface (SEI).
[0003] Studies have shown that reducing the silicon particle size below a certain threshold can alleviate crushing. For crystalline silicon, this size is about 150nm, with particles above this size prone to crushing. Therefore, most of the research and development work in silicon anode technology is directed to the use of nanosized silicon particles. Although nanosized silicon particles enhance cycle stability, it also leads to reduced material availability. Micron-sized silicon particles are preferred because they reduce SEI formation. The strategy of using silicon particles larger than the threshold (including micron-sized particles) can enable a wider adoption of silicon-based solid-state battery technology. In addition, the low electronic conductivity of silicon of about 10^-5S / cm poses another challenge. This emphasizes the need for significant progress in enhancing the electronic conductivity of silicon particles to overcome the limitations faced by silicon anodes in solid-state batteries. Summary of the Invention
[0004] According to one aspect of the present disclosure, a lithium-ion battery component is provided. The lithium-ion battery component has an electrode having a current collector and a silicon-based active layer adhered to the current collector. The silicon-based active layer includes coated silicon beads connected by carbon chains to form a fiberized conductive silicon-carbon necklace, and the fiberized conductive silicon-carbon necklace is configured to constrain the silicon beads via the carbon chains during the volume expansion and contraction of the electrode during the charging cycle. The silicon-carbon necklace may have a diameter of 0.1um-10um. The silicon-carbon necklace may have a length of less than 100 microns. In some configurations, the silicon-carbon necklace has a length of less than 10 microns. The silicon-carbon necklace may have a silicon content range of 30-80% by weight. The silicon beads may have a diameter greater than 100nm.
[0005] In another aspect of the present disclosure, a solid-state battery is provided. The solid-state battery includes a separator and a pair of electrodes sandwiching the separator. At least one of the electrodes includes a silicon-based active layer, the silicon-based active layer having silicon particles encapsulated and conductively interconnected by carbon chains, the carbon chains being configured to maintain conductive contact between the silicon particles in a lithiated state. The silicon-based active layer may include a carbon additive. The silicon-based active layer may include a solid electrolyte. The solid electrolyte may be sulfide-based. The silicon-based active layer may have a silicon content in the range of 30 wt% to 80 wt%. The silicon particles may have a diameter greater than 100 nm.
[0006] In yet another aspect of the present disclosure, a method is presented. The method begins by electrospinning a solution of dissolved silicon precursors and carbon precursors to form agglomerates of silicon-carbon necklaces, each of which is defined by coated silicon beads linked by carbon chains. The silicon-carbon necklaces are then carbonized to form carbonized silicon-carbon necklaces. Finally, the carbonized silicon-carbon necklaces are fiberized to form fiberized silicon-carbon necklaces. The silicon precursor and the carbon precursor may be dissolved in dimethylformamide. The agglomerates may contain 13 wt% silicon precursor. The silicon precursor and the carbon precursor may be present in a ratio of 1:2 by weight. The silicon precursor may have an average diameter of 400 nm. In some configurations, the method may further include mixing the fiberized silicon-carbon necklaces with solid electrolyte particles, a carbon additive, and a polymer binder to form a slurry. The slurry may be applied to a current collector and cured to form an anode. The anode may be packaged with a separator and a cathode to form a solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Figure 1A is a graph showing the effect of particle size on the first cycle voltage;
[0008] Figure 1Bis a table showing the effect of particle size on capacity and coulombic efficiency;
[0009] Figure 1C is a graph showing the effect of particle size on discharge capacity;
[0010] Figure 2A is a graph of the cycling stability of currently available silicon-carbon composites;
[0011] Figure 2B is a graph of the internal resistance of currently available silicon-carbon composites;
[0012] Figure 3 is a schematic diagram of a lithium-ion battery according to one or more embodiments of the present disclosure;
[0013] Figure 4 is a schematic diagram of a lithium-ion battery component according to one or more embodiments of the present disclosure;
[0014] Figure 5A and Figure 5B is a schematic diagram of a silicon-carbon necklace according to one or more embodiments of the present disclosure;
[0015] Figure 6A and Figure 6B is a schematic diagram of a silicon-carbon necklace according to one or more embodiments of the present disclosure;
[0016] Figure 7A is a graph showing capacity retention of an electrode having a silicon-carbon necklace according to one or more embodiments of the present disclosure;
[0017] Figure 7B is a graph illustrating voltage distribution of an electrode having a silicon-carbon necklace according to one or more embodiments of the present disclosure;
[0018] Figure 7C is a graph illustrating differential capacity of electrodes having a silicon-carbon necklace according to one or more embodiments of the present disclosure; and
[0019] Figure 8 is a flow chart of a method of making a fiberized silicon-carbon necklace according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION
[0020] Embodiments are described herein. However, it should be understood that the disclosed embodiments are merely examples and that other embodiments may take various and alternative forms. The drawings are not necessarily drawn to scale. Some features may be exaggerated or minimized to illustrate details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art.
[0021] The various features shown and described with reference to any one of the accompanying drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, for specific applications or implementations, various combinations and modifications of features may be desired consistent with the teachings of this disclosure.
[0022] The present disclosure relates to a silicon-carbon material and a method for making the same. The silicon-carbon composite can be configured to improve the cycling stability of silicon-based anodes in solid-state batteries. The silicon-carbon composite can have a "necklace-like" morphology in which silicon domains are coated with a carbon layer and interconnected by carbon nanofibers. This electron transport across the electrodes can also provide mechanical support to the silicon domains, allowing them to withstand the pressure caused by volume expansion during the charge and discharge cycles of the battery. The silicon-carbon composite can also improve the conductivity and mechanical integrity of the particulate material within the battery, resulting in improved cycling stability and overall battery performance. The design of this composite is also intended to mitigate solid electrolyte interface (SEI) formation. By limiting the growth of the SEI layer, the composite helps maintain the ionic conductivity and structural integrity of the electrode through multiple cycles.
[0023] In one aspect of the present disclosure, a composition of a precursor solution for making silicon-carbon necklaces is proposed. The composition is determined to be 13 wt% solids in dimethylformamide (DMF) (wherein the ratio of silicon nanoparticles (SiNPs) to polyacrylonitrile (PAN) is 1:2) and 400 nm silicon nanoparticles. The formulation is used to achieve a "necklace-like" morphology of silicon-carbon composites, which plays a role in improving the cycling stability of silicon-based anodes in solid-state batteries. The silicon domains within the composite are uniformly coated with a carbon layer from the precursor solution and interconnected by carbon nanofibers. This structure promotes electron transport across the electrodes and provides mechanical support to the silicon domains. The support can accommodate the pressure induced by volume expansion during the charge and discharge cycles of the battery, thereby reducing mechanical degradation and loss of electrical connectivity within the electrode.
[0024] The fabrication of silicon-carbon necklaces can be accomplished through electrospinning, in which a mixture of silicon and carbon precursors is spun, followed by a carbonization process to solidify the structure. Alternatively, these particles can also be produced using an extrusion process that involves extruding a similar precursor mixture. Both methods uniformly coat the silicon domains within the composite with a carbon layer and interconnect them with carbon nanofibers, creating a robust framework that supports electron transport and mechanical integrity under operating cycles.
[0025] An experiment was set up to characterize the effect of silicon particle size on the electrochemical properties of solid-state battery cells. Silicon was loaded at a density of 1.4 mg / cm^2 into three test samples with silicon particle sizes of 100 nm, 400 nm, and 1 μm. Figure 1A In , a graph showing the effect of particle size on the first cycle voltage is presented. It is observed that the first cycle voltage is related to the particle size of the silicon used. For the sample containing 100 nm particle size silicon, a significant increase in the results is shown. In Figure 1B , a table showing the effect of particle size on capacity and coulombic efficiency is presented. Similarly, it can be observed that the sample with 100 nm silicon particles has higher capacity and internal coulombic efficiency than the samples with 400 nm and 1 um silicon particles, respectively. Figure 1C is a graph showing the effect of particle size on discharge capacity. The sample with 100 nm silicon particles has increased discharge capacity at 0.2 C compared to the samples with 400 nm and 1 μm silicon particles, respectively.
[0026] In another test setup, a commercially available silicon-carbon material was evaluated for its performance in both the delithiated and lithiated states. The silicon-carbon material was loaded into a half-cell with a solid electrolyte sheet and lithium at a density of 1.35 mg / cm². Figure 2A is a graph showing the cycling stability of currently available silicon-carbon composites in their lithiated and delithiated states. Figure 2B Figure 2 is a graph of the internal resistance of currently available commercially available silicon-carbon composites. Commercially available silicon-carbon materials exhibit poor cycling performance. Rapid capacity fade can be attributed to conduction path losses, as reflected by the increasing direct current internal resistance (DC-IR) in the fully lithiated state.
[0027] Now refer to Figures 3 to 6B , Figure 3 is a schematic diagram of a lithium-ion battery 10 according to one or more embodiments of the present disclosure. The lithium-ion battery 10 shown is a solid-state battery 10 having a pair of lithium-ion battery components 12 and 14 sandwiched by a separator 16. The lithium-ion battery component 14 is shown as an electrode, which includes a silicon-based active layer 18 having silicon particles 20 encapsulated and conductively interconnected by carbon chains 22. The silicon particles 20 have a diameter greater than 100 nm. The carbon chains 22 are configured to maintain conductive contact between the silicon particles in the lithiated state. As shown, the silicon-based active layer 18 is incorporated into the lithium-ion battery component 14, which is an electrode used as an anode.
[0028] Figure 4An electrode 14 is shown having a current collector 24 and a silicon-based active layer 18 adhered to the current collector. The silicon-based active layer 18 includes coated silicon beads 20 connected by carbon chains 22 to form a fiberized, conductive silicon-carbon necklace 26. The silicon-carbon necklace 26 is configured to constrain the silicon beads 20 via the carbon chains 22 during volume expansion and contraction of the electrode 14 during a charging cycle. In some configurations, the silicon-carbon necklaces 26 may have a diameter ranging from 0.1 μm to 10 μm and a length that may be less than 100 microns. In certain embodiments, the length of these necklaces 26 may be less than 10 microns. In addition, the silicon content within the silicon-carbon necklaces 26 is targeted to be in the range of 30% to 80% by weight, depending on the specific application and desired electrochemical performance in the solid-state battery. The silicon-based active layer 18 is also shown to include solid electrolyte particles 28 and carbon additives 30. The solid electrolyte particles 28 may be sulfide particles.
[0029] Figure 5A A silicon-carbon necklace 32 is shown having coated silicon beads 20 connected by carbon chains 22 in a closed necklace formation. However, the silicon-carbon necklace 32 can also be in an open configuration, such as Figure 5B shown. Figure 6A The silicon-carbon necklace 32 is shown in the delithiated state. When the lithiation process occurs, the silicon particles 20 that are broken apart due to volume expansion maintain conductive contact due to the carbon chains 22, as shown in FIG. Figure 6B shown.
[0030] 7A to 7C Experimental results are shown regarding the performance of lithium-ion batteries using silicon-carbon necklaces 26. Compared to batteries with bare silicon particles, those batteries incorporating silicon-carbon necklaces 26 exhibited higher capacity and capacity retention, as shown in FIG. Figure 7A and Figure 7B This increase is attributed to the structural stability of the silicon-carbon necklace 26, which mitigates the effect of volume changes during cycling. Figure 7C A stable differential capacity (dQ / dV) peak is shown, indicating consistent electrochemical behavior. These results were obtained from a half-cell configuration with a silicon loading of 0.9 mg / cm^2.
[0031] Figure 8is a flow chart of a method for making a fiberized silicon-carbon necklace 34 according to one or more embodiments of the present disclosure. Box 36 begins, where a solution of dissolved silicon precursor and carbon precursor is electrospun to form agglomerates of silicon-carbon necklaces, each silicon-carbon necklace being defined by coated silicon beads linked by carbon chains. Then, in box 38, the silicon-carbon necklaces are carbonized to form carbonized silicon-carbon necklaces. Finally, in box 40, the carbonized silicon-carbon necklaces are fiberized to form fiberized silicon-carbon necklaces. The silicon precursor and the carbon precursor can be dissolved in a solvent such as dimethylformamide or any other suitable solvent. The agglomerates can contain 13 weight percent silicon precursor. The silicon precursor and the carbon precursor can be mixed in a ratio of 1:2 by weight. The silicon precursor can have an average diameter of 400 nm. In some configurations, the method can also include mixing the fiberized silicon-carbon necklaces with solid electrolyte particles, a carbon additive, and a polymer binder to form a slurry. The slurry can then be applied to a current collector and cured to form an anode. The method then includes packaging the anode with a separator and a cathode to form a solid-state battery.
[0032] Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it should be understood that various changes can be made without departing from the spirit and scope of these disclosures.
[0033] As previously mentioned, features of the various embodiments may be combined to form additional embodiments of the invention that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, it will be recognized by those of ordinary skill in the art that one or more features or characteristics may be compromised to achieve desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to, strength, durability, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, and the like. Therefore, embodiments that are described as being less desirable than other embodiments or prior art implementations with respect to one or more characteristics are within the scope of this disclosure and may be desirable for a particular application.
[0034] According to the present invention, a lithium-ion battery component is provided, comprising: an electrode having a current collector and a silicon-based active layer adhered to the current collector, the silicon-based active layer comprising coated silicon beads connected by carbon chains to form a fiberized conductive silicon-carbon necklace, the fiberized conductive silicon-carbon necklace being configured to constrain the coated silicon beads via the carbon chains during volume expansion and contraction of the electrode during a charging cycle.
[0035] According to one embodiment, the fiberized conductive silicon-carbon necklace has a diameter of 0.1 um-10 um.
[0036] According to one embodiment, the fiberized conductive silicon-carbon necklace has a length of less than 100 microns.
[0037] According to one embodiment, the fiberized conductive silicon-carbon necklace has a length of less than 10 microns.
[0038] According to one embodiment, the fiberized conductive silicon-carbon necklace has a silicon content in the range of 30 wt % to 80 wt %.
[0039] According to one embodiment, the coated silica beads have a diameter greater than 100 nm.
[0040] According to the present invention, a solid-state battery is provided, comprising: a separator; and a pair of electrodes, wherein the separator is sandwiched between the pair of electrodes, at least one of the electrodes includes a silicon-based active layer, wherein the silicon-based active layer has silicon particles encapsulated and conductively interconnected by carbon chains, wherein the carbon chains are configured to maintain conductive contact between the silicon particles in a lithiated state.
[0041] According to one embodiment, the silicon-based active layer contains carbon additives.
[0042] According to one embodiment, the silicon-based active layer comprises a solid electrolyte.
[0043] According to one embodiment, the solid electrolyte is sulfide based.
[0044] According to one embodiment, the silicon-based active layer is 30 wt% to 80 wt% silicon particles.
[0045] According to one embodiment, the silicon particles have a diameter greater than 100 nm.
[0046] According to the present invention, a method includes: electrospinning a solution of dissolved silicon precursors and carbon precursors to form agglomerates of silicon-carbon necklaces, each silicon-carbon necklace being defined by coated silicon beads linked by carbon chains; carbonizing the agglomerates of silicon-carbon necklaces to form carbonized silicon-carbon necklaces; and fiberizing the carbonized silicon-carbon necklaces to form fiberized silicon-carbon necklaces.
[0047] In one aspect of the present invention, the dissolved silicon precursor and carbon precursor are dissolved in dimethylformamide.
[0048] In one aspect of the invention, the agglomerates of silicon-carbon necklaces contain 13 wt% silicon precursor.
[0049] In one aspect of the invention, the dissolved silicon precursor and carbon precursor are present in a ratio of 1 :2 by weight.
[0050] In one aspect of the invention, the particles of the dissolved silicon precursor have an average diameter of 400 nm.
[0051] In some configurations, the method includes mixing fiberized silicon-carbon necklaces with solid electrolyte particles, a carbon additive, and a polymer binder to form a slurry.
[0052] In one aspect of the present invention, the method includes coating the slurry on a current collector and curing to form an anode.
[0053] In one aspect of the invention, the method includes packaging the anode with a separator and a cathode to form a solid-state battery.
Claims
1. A lithium-ion battery component comprising: An electrode having a current collector and a silicon-based active layer adhered to the current collector, the silicon-based active layer comprising coated silicon beads connected by carbon chains to form a fiberized conductive silicon-carbon necklace, the fiberized conductive silicon-carbon necklace being configured to constrain the coated silicon beads via the carbon chains during volume expansion and contraction of the electrode during a charging cycle.
2. The lithium-ion battery component of claim 1, wherein the fiberized conductive silicon-carbon necklace has a diameter of 0.1 um to 10 um.
3. The lithium-ion battery component of claim 1 , wherein the fiberized conductive silicon-carbon necklace has a length of less than 100 microns.
4. The lithium ion battery component of claim 1 , wherein the fiberized conductive silicon-carbon necklaces have a length of less than 10 microns.
5. The lithium-ion battery component of claim 1, wherein the fiberized conductive silicon-carbon necklace has a silicon content in the range of 30 wt% to 80 wt%.
6. The lithium ion battery component of claim 1, wherein the coated silica beads have a diameter greater than 100 nm.
7. A solid-state battery comprising: partitions; as well as A pair of electrodes sandwiching the separator, at least one of the electrodes comprising a silicon-based active layer having silicon particles encapsulated and conductively interconnected by carbon chains, the carbon chains configured to maintain conductive contact between the silicon particles in a lithiated state.
8. The solid-state battery of claim 7, wherein the silicon-based active layer comprises a carbon additive.
9. The solid-state battery of claim 7, wherein the silicon-based active layer comprises a solid electrolyte.
10. The solid-state battery of claim 9, wherein the solid electrolyte is sulfide-based.
11. The solid-state battery of claim 7, wherein the silicon-based active layer is 30 wt% to 80 wt% silicon particles.
12. The solid-state battery of claim 7, wherein the silicon particles have a diameter greater than 100 nm.
13. A method comprising: electrospinning a solution of dissolved silicon precursors and carbon precursors to form agglomerates of silicon-carbon necklaces, each defined by coated silicon beads linked by carbon chains; carbonizing the agglomerates of silicon-carbon necklaces to form carbonized silicon-carbon necklaces; as well as The carbonized silicon-carbon necklace is fiberized to form a fiberized silicon-carbon necklace.
14. The method of claim 13, wherein the dissolved silicon precursor and carbon precursor are dissolved in dimethylformamide.
15. The method of claim 13, wherein the agglomerates of silicon-carbon necklaces contain 13 wt% silicon precursor.