Silicon-sulfur battery and corresponding method for assembling the battery

Abstract

The present invention relates to an improved silicon-sulfur battery and corresponding method for assembling the battery, which uses silicon and sulfur as its key materials, so that, when combined with other elements, it plays an important role in accelerating the transition towards cleaner and more sustainable energy sources, wherein the battery comprises at least one anode current collector, at least one anode, at least one separator, at least one cathode, and at least one cathode current collector.

Description

[0001] Silicon-sulfur battery and its assembly method. Field of the invention.

[0002]

[0001] The present invention relates to an improved silicon-sulfur battery and its respective battery assembly method, which is especially, but not exclusively, applied in electric vehicles, increasing range and consequently reducing costs, mobile devices, since it increases the battery life of smartphones, laptops or other devices, and for renewable energy storage, such as solar and wind. Advantageously, the composition of the elements that make up the battery provides a synergistic effect, which is responsible for the significant leap in performance and safety, compared to existing batteries.

[0003] BACKGROUND OF THE INVENTION AND PRIOR ART

[0004]

[0002] A battery is an accumulator that transforms chemical energy into electrical energy through oxidation-reduction reactions. During battery discharge, the negative pole, called the anode, is where oxidation occurs. In this process, materials in the anode lose electrons, which are released into the external circuit, and form positive ions that move to the electrolyte. The positive pole, known as the cathode, is where reduction occurs; the electrons that travel through the external circuit are captured by the positive ions that have migrated through the electrolyte, completing the reaction by reducing these ions. This flow of electrons through the external circuit is what generates electrical energy. During this process, the electrolyte plays an essential role by allowing the movement of ions between the electrodes, maintaining electrical neutrality and enabling the continuity of electrochemical reactions in the battery.

[0005]

[0003] At the beginning of the 20th century, automotive batteries were part of a revolution, becoming one of the various industries that were established with the growing spread of automobiles. They were introduced in 1912, when they assumed a role similar to the current one, replacing the ignition crank and serving to power the lights.

[0006]

[0004] Currently, all motor vehicles contain batteries, as they serve as a power source for auxiliary systems, which have grown in number, and for specific tasks such as ignition.

[0005] Although in hybrid and electric vehicles the battery plays a primary role, it is generally different from those traditionally used. As batteries become responsible for other functions, such as traction, the need for energy is increasingly greater, creating a barrier for the traditional technology (lead-acid battery) present in current vehicles, for which Brazil has a large industrial base.

[0007]

[0006] This barrier stems from the volume and, above all, the weight of these batteries, which would not be compatible with an electric vehicle, although there is some room for applications in some types of hybrids. Lithium-ion batteries, which are lighter and have a higher energy density, then emerge as the likely dominant technology.

[0008]

[0007] In general, a lithium-ion battery consists of a separator, an electrolyte, a cathode, and an anode. The electrodes are usually manufactured by dispersing finely ground powders of an active electrode material, along with a conductive agent and a binding polymer, in a suitable solvent. This mixture is then applied to a conductive substrate, such as a copper foil for the anode or aluminum for the cathode. After application, the structure is then dried to evaporate the solvent, consolidating the electrode matrix. The cathode and anode wafers are then assembled in an alternating configuration, with the separator interposed between them to prevent short circuits, and submerged in electrolyte. This arrangement allows for effective immersion and homogenization of the electrolyte in the pores of the electrodes, completing the battery assembly.

[0009]

[0008] However, lithium-ion batteries have some drawbacks, such as their fragility and the need for a protection circuit to maintain safe operation. Embedded within each pack, the protection circuit limits the peak voltage of each cell during charging and prevents the cell voltage from dropping too low during discharge. In addition, the maximum charge and discharge current is limited, and the cell temperature is monitored to prevent extreme temperatures.

[0010]

[0009] Aging is a concern with most batteries. Some capacity deterioration is noticeable after one year, whether the battery is in use or not. After two or perhaps three years, the battery frequently fails. Other chemical compositions also used have age-related degenerative effects, especially for NiMH batteries when exposed to high-temperature environments.

[0010] Another significant challenge is the limited availability and cost of critical battery manufacturing materials such as cobalt, nickel, and lithium. These materials are mined in specific locations around the world, raising concerns about security of supply and the environmental and social impacts of mining.

[0011]

[0011] In light of these challenges, it is imperative that there be a renewed focus on the development of new battery technologies, as these must be able to overcome the limitations of current batteries, offering greater storage capacity, extended lifespan, improved safety, and the use of more abundant and sustainable materials.

[0012]

[0012] Thus, documents are found in the state of the art that disclose battery compositions and / or parts of the components that constitute them. An example is described in document US9899667, entitled "Electrode composite material, method thereof, positive electrode and battery, including the same", filed on 11 / 06 / 2011, which discloses a positive electrode composite material configured by ABxCyDz, wherein A is selected from polypyrrole, polyacrylonitrile and polyacrylonitrile copolymer; B comprises sulfur; C is selected from carbon material; D is selected from metallic oxides.It is noted that although the composite uses boron-doped porous silicon, said composite does not include elements that significantly impact battery performance and safety, nor does it include elements that reduce the formation of dendrites, needle-shaped crystalline structures that can form in lithium-ion batteries and puncture the separator, causing short circuits and damaging the battery.

[0013]

[0013] Another example is document US9362557, entitled "Active negative electrode material for electrical devices", filed on 07 / 03 / 2011, which refers to an active negative electrode material for an electrical device that includes an alloy comprising silicon, aluminum, niobium and unavoidable impurities as residue. Disadvantageously, they present a high risk of catastrophic failure, such as short circuits and fires, compromising safety.

[0014] The state of the art is presented in documents CN116666748, dated 08 / 29 / 2023, CN116666609, dated 08 / 29 / 2023, CN117154182, dated 12 / 01 / 2023, CN118016987, dated 05 / 10 / 2024 and US20140272569, dated 09 / 18 / 2014, but they are not of particular relevance, considering that none of the cited documents reveals electrodes with dopants, as claimed in the present patent application which, in summary, refers to a silicon-sulfur battery, polymeric gel electrolyte, electrodes mounted superimposed inside an envelope filled with electrolyte.

[0014]

[0015] Furthermore, there are companies in the state of the art seeking to develop silicon-sulfur solid-state batteries with an energy density of up to 500 Wh / kg. However, the specified parameters still exhibit a relatively high self-discharge, which makes their application in electric vehicles unfeasible and therefore requires improvements.

[0015]

[0016] Aiming for a technically and cost-effective solution, the present invention discloses a silicon-sulfur battery composition with a significantly higher potential energy density than lithium-ion batteries, making them attractive for applications requiring high energy storage capacity.

[0016]

[0017] Silicon and sulfur are highly promising materials for use in anodes and cathodes of lithium-ion batteries, respectively, due to their exceptional energy storage capacities. Silicon, with a theoretical capacity of approximately 4200 mAh / g, offers almost ten times more capacity than graphite, the current standard anode material (372 mAh / g). This makes silicon ideal for applications demanding high energy density, such as electric vehicles and long-lasting mobile devices. Furthermore, its abundance in the Earth's crust and lower environmental impact compared to other heavy metals used in batteries make it a sustainable and economically viable resource.

[0017]

[0018] On the other hand, sulfur, used as a cathode material, stands out for its theoretical capacity of approximately 1620 mAh / g, significantly exceeding traditional cathode materials. This can result in batteries that offer greater longevity between recharges, suitable for long-range electric vehicles and large-scale energy storage systems. The abundance and accessibility of sulfur also contribute to reducing costs and ensuring a more stable supply chain that is less dependent on scarce resources.

[0018]

[0019] Although silicon offers substantially superior energy storage capacity compared to graphite, its use as an anode in lithium-ion batteries faces significant challenges due to its volumetric expansion and contraction during charge and discharge cycles. This expansion can triple the original volume of the silicon, causing fractures and structural deterioration that compromise battery lifespan. Furthermore, the expansion negatively affects the anode / electrolyte interface and can result in the formation of an unstable solid-electrolyte interface (SEI) layer, which increases electrolyte and lithium ion consumption, reducing efficiency and increasing safety risks.

[0019]

[0020] Silicon's low electrical conductivity also limits the battery's charge and discharge rate, affecting its performance in high-energy-demand applications. Additionally, the fabrication of high-purity silicon nanostructures, necessary to mitigate expansion problems, is complex and expensive, hindering scalability and mass adoption.

[0020]

[0021] Regarding sulfur, it faces the so-called "shuttle effect," where soluble polysulfides migrate between the cathode and anode, causing loss of active material and degrading the electrolyte. This phenomenon reduces battery efficiency and lifespan and increases safety risks due to chemical instability. The low electrical conductivity of sulfur is another obstacle, limiting the charging rate and resulting in inefficient use of the cathode material.

[0021]

[0022] The cyclic stability of sulfur cathodes and long-term capacity retention are also challenging, with expansion and contraction during load cycles compromising performance. Furthermore, the need to optimize the electrolyte design to accommodate sulfur reactivity and minimize the "shuttle effect" requires the development of new electrolytes or additives, which can be expensive and technically challenging on a large scale.

[0022] SUMMARY OF THE INVENTION

[0023] Thus, it is an objective of the present invention to provide a silicon-sulfur battery composition endowed with other elements that promote a substantial synergistic effect, such as, for example, the addition of boron which improves the conductivity of silicon, as well as the inclusion of specific oxides such as niobium and titanium, which reinforce structural stability and reduce the formation of dendrites, raising the overall performance of the battery to a superior level.

[0023]

[0024] Furthermore, the combination of the pre-lithiated silicon nanoparticle anode with the mesoporous carbon matrix cathode reinforced with carbon nanotubes and doped with integrated sulfur-containing tin and iron oxides optimizes lithium ion transfer, reduces polysulfide dissolution in the electrolyte, and contains silicon expansion and contraction, improving charge and discharge efficiency. The ionogel electrolyte based on polyvinylidene fluoride and polyethylene glycol, structured with aluminum oxide and antimony oxide nanoparticles and enriched with lithium salts, works to enhance ionic conductivity and battery safety.

[0024]

[0025] Another objective of the present invention is to provide a battery that offers improved safety in terms of fire risk, compared to lithium-ion batteries, given that the proposed battery does not comprise highly reactive materials, such as nickel in the cathode.

[0025]

[0026] Another objective of the present invention is to provide a battery with a very high theoretical capacity compared to the state of the art due to the intrinsic characteristics of the active electrode materials, silicon and sulfur, which have capacities of 4200 mAh / g and 1672 mAh / g respectively, making them ideal for high-energy applications, such as long-range electric vehicles.

[0026]

[0027] Another objective of the present invention is to provide a method for assembling silicon-sulfur batteries that provides better adhesion and consistency of the layers, which can lead to more stable and efficient electrochemical performance.

[0027]

[0028] Other objectives, features and advantages of the invention will become apparent from the following detailed description when taken together with the accompanying figures.

[0028] BRIEF DESCRIPTION OF THE FIGURES

[0029] Figure 1 illustrates a graph comparing the specific capacity of sulfur, the LFP (Lithium Ferrophosphate) cathode, and the NMC811 (Nickel-Manganese-Cobalt) cathode.

[0029]

[0030] Figure 2 illustrates a graph comparing the lifespan of sulfur, the LFP (Lithium Ferrophosphate) cathode, and the NMC811 (Nickel-Manganese-Cobalt) cathode;

[0030]

[0031] Figure 3 illustrates a graph comparing the electrical conductivity of sulfur, the LFP (Lithium Ferrophosphate) cathode, and the NMC811 (Nickel-Manganese-Cobalt) cathode.

[0031]

[0032] Figure 4 illustrates a graph comparing the ionic conductivity of a liquid electrolyte, an ionogel, and a solid electrolyte.

[0032]

[0033] Figure 5 illustrates a graph comparing the thermal stability of a liquid electrolyte, an ionogel, and a solid electrolyte.

[0033]

[0034] Figure 6 illustrates a graph comparing the specific capacitance of silicon, graphite, and lithium metal anodes.

[0034]

[0035] Figure 7 illustrates a graph comparing the cyclable stability of silicon, graphite, and lithium metal anodes.

[0035] DETAILED DESCRIPTION OF THE INVENTION

[0036]

[0036] The present invention discloses an improved battery that uses silicon and sulfur as its key materials, so that, combined with other elements, it plays an important role in accelerating the transition towards cleaner and more sustainable energy sources.

[0037]

[0037] Thus, compared with conventional Li / S and lithium-ion batteries, the materials and structure of the cathode and anode and the composition of the electrolytes described in this document improve the performance, manufacturability and / or stability of the batteries.

[0038]

[0038] For this purpose, the present invention discloses a battery comprising at least one anodic current collector, at least one anode, at least one separator, at least one cathode and at least one cathodic current collector, which are described in more detail below:

[0039] CURRENT COLLECTORS

[0039] The current collector for the cathode is, for example, Copper (Cu), Titanium (Ti), Platinum (Pt), Lead (Pb) films or, preferably, Aluminum (Al) films. The current collector for the anode is, for example, Titanium (Ti), Platinum (Pt), Lead (Pb) or, preferably, Copper (Cu) films. Graphene in oxide (GO) or reduced oxide (rGO) form may also be applied as a current collector in future versions of the battery, due to its excellent electrical and mechanical properties, as well as its high specific surface area and chemical stability.

[0040] Cathode for SL-S battery

[0041]

[0040] The cathode for the proposed Silicon-Sulfur (Si / S) ion battery is configured by a mesoporous carbon matrix reinforced with carbon nanotubes and doped with tin and iron oxides, containing integrated sulfur. The matrix has excellent electrical conductivity and adequate porosity to accommodate the sulfur during electrochemical reactions.

[0042]

[0041] Mesoporous carbon is prepared by pyrolysis and the matrix is ​​formed by dispersing carbon nanotubes in ethanol, forming a uniform suspension. In one embodiment of the invention, the process for obtaining mesoporous carbon begins with the oxidation of polystyrene in a solution of sulfuric acid and hydrogen peroxide, in order to introduce functional groups into the PS, preparing it for subsequent steps.

[0043]

[0042] The cathode is doped with tin and iron oxides to improve the reactivity of sulfur and its stability. Thus, tin and iron oxides are introduced into the mesoporous carbon matrix through a doping process that involves immersing the substrate in a combined solution prepared using 4 g of SnCl4, 5 g of FeCl3 and 0.4 g of ascorbic acid (reducing agent) for each 100 mL of ethanol. This step facilitates the formation of SnO2 and Fe2O3 in the substrate.

[0044]

[0043] Thus, in this doping step with tin and iron oxides, the combined solution is prepared using 4 g of SnCl4, 5 g of FeCl3 and 0.4 g of ascorbic acid for each 100 mL of ethanol.

[0044] The carbonization of the mesoporous carbon substrate is carried out by heating the sample to 1000°C in an inert argon atmosphere, forming a porous structure capable of supporting sulfur impregnation.

[0045]

[0045] The sulfur cathode is prepared by impregnating the mesoporous carbon substrate doped and reinforced with carbon nanotubes in a sulfur and toluene suspension. In this impregnation process, the substrate is immersed for 10 to 14 hours between 23°C and 26°C in a solution prepared with 15 to 20 g of powdered sulfur for every 200 mL of toluene, with agitation at approximately 300 rpm. This step ensures adequate impregnation of the sulfur into the pores of the carbon matrix.

[0046]

[0046] After impregnation, the substrate is dried between 65 and 75°C to ensure the incorporation of sulfur, preparing it for effective battery operations.

[0047]

[0047] Thus, the cathode proposed by the present invention comprises the following composition in weight percentage:

[0048] - 20 to 30% carbon;

[0049] - 40 to 60% sulfur;

[0050] - 10 to 15% tin oxide; and

[0051] - 10 to 15% iron oxide.

[0052]

[0048] Iron and tin oxides are used to combat the dissolution of polysulfides in the electrolyte. These oxides act as catalysts, promoting the reconversion of polysulfides back to elemental sulfur during the recharge cycle, a crucial process for the reversibility of electrochemical reactions and for increasing battery efficiency and lifespan. The heat treatment stage includes carbonization, sulfur addition, and final heat treatment, aiming to improve electrical conductivity, energy storage capacity, and structural stability.

[0053]

[0049] As observed in Figure 1, the greatest advantage of this cathode is the significantly higher theoretical energy density due to the high capacity of sulfur, which is 1675 mAh / g. Comparatively, the energy density of the LFP (Lithium Ferrophosphate) cathode is approximately 170 mAh / g, while that of the NMC811 (Nickel-Manganese-Cobalt) cathode is about 200 mAh / g. In practice, the energy density of the cathode is reduced due to the dissolution of polysulfides and volumetric expansion during the cycles, but with the implemented strategies, it is possible to achieve a practical density of approximately 800 mAh / g. This capacity can be increased by increasing the sulfur-to-carbon ratio; however, this variation may bring even more challenges regarding the management of polysulfides.

[0054]

[0050] The life cycle of Si / S batteries is challenging precisely because of the formation and dissolution of these polysulfides; however, doping strategies and the incorporation of carbon nanotubes help improve cycle stability. In practice, the cathode is able to maintain about 80% of its initial capacity after 1000 cycles, showing a decay of only 0.0166% of capacity per cycle. As shown in Figure 2, in comparison, LFP and NMC811 batteries show greater cycle stability, with LFP batteries maintaining more than 80% of their initial capacity after 2000 cycles, and NMC811 batteries maintaining about 80% of their initial capacity after 1500 cycles. An approach that could extend this lifespan is the inclusion of a solid electrolyte and the replacement of the carbon matrix with a sulfur copolymer matrix in future versions of this battery.

[0055]

[0051] Another challenge of sulfur cathodes is their low electrical conductivity. This characteristic results in less efficient electron transfer during charge and discharge cycles, which can lead to limited charge capacity and a sharp drop in capacity over time. As shown in Figure 3, the results showed that the strategy of using a carbon matrix reinforced with carbon nanotubes and doping with tin and iron oxides was effective in increasing the electrical conductivity of the cathode, exhibiting a total electrical conductivity of approximately 10⁻¹ S / cm, significantly higher than that of LFP cathodes (10⁻² S / cm with added conductors) and similar to NMC811 (10⁻¹ S / cm with added conductors). The internal resistance of the cathode was reduced to about 50 ohms, compared to more than 200 ohms in conventional sulfur cathodes.

[0056] ELECTROLYTE

[0057]

[0052] The ionogel electrolyte for Silicon-Sulfur batteries is composed of polyvinylidene fluoride dissolved in polyethylene glycol-400, dimethyl carbonate, and dimethylformamide, using 13 to 17 g of polyvinylidene fluoride for every 40 mL of polyethylene glycol-400, 30 mL of dimethyl carbonate, and 10 mL of dimethylformamide. The mixture is enriched with 1 to 3 g of lithium hexafluorophosphate and 1 to 3 g of lithium hydroxide to optimize ionic conductivity and provide the ions for the battery to function, while 0.3 to 0.7 g of aluminum oxide nanoparticles and 2 to 4 g of antimony nanoparticles are added to reinforce thermal resistance and reduce the flammability of the ionogel.

[0058]

[0053] Thus, for the preparation of the ionogel electrolyte, PVDF is dissolved in the PEG-400, DMC and MDF solution under heating and stirring, preferably heated to 70°C and controlled stirring at 600 rpm. This step is crucial to achieve a homogeneous dispersion of the polymer, which serves as a base matrix for the incorporation of lithium salts and aluminum nanoparticles.

[0059]

[0054] After complete dissolution of PVDF, LiPF6 and UOH-H2O are added to the heated solution. The mixture is constantly stirred to ensure complete homogenization of the salts, promoting optimized ionic conductivity and adjusting the pH between 7 and 8 to maintain the chemical and electrochemical stability necessary for battery operation.

[0060]

[0055] In one embodiment of the invention, the synthesis takes place during continuous heating of the solution between 65 and 75°C, allowing the reaction to occur uniformly. At this stage, the interactions between the components are optimized, promoting the formation of a high-quality ionogel electrolyte. During the synthesis, the PEG-400 molecules organize themselves around the Li+ ions from the LiPF. s and LiOH, forming an ionic conducting matrix. This structure facilitates the transport of Li+ ions in the electrolyte, which is essential for its function in electrochemical devices.

[0061]

[0056] Next, any impurities that may be present in the solution are removed, preferably by filtration, ensuring the purity of the electrolyte. The resulting electrolyte is then stored in a hermetically sealed container under an inert atmosphere. This storage process preserves the purity and effectiveness of the electrolyte over time, making it ready for application in energy storage systems and electrochemical devices.

[0062]

[0057] The thermal stability and flame resistance of the ionogel are enhanced by the presence of aluminum oxide nanoparticles, which also contribute to maintaining structural integrity under diverse operating conditions.

[0058] In another embodiment of the invention, polyethylene glycol can be replaced by polyethylene glycol-β-dimethylsiloxane as the solvent for the electrolyte. Polyethylene glycol-β-dimethylsiloxane is a cheaper material than polyethylene glycol, but still offers good thermal and chemical stability. Furthermore, PEG can be replaced by other non-toxic solvents, such as ethylene glycol (EG) or glycerol.

[0063]

[0059] In another embodiment, it is understood that the synthesis can occur via sol-gel, hydrothermal, precipitation, solvothermal, electrochemical, combustion, chemical vapor deposition (CVD), physical vapor deposition (PVD), laser melting, high-energy milling or microwave.

[0064]

[0060] As shown in Figure 4, the ionic conductivity of ionogel, theoretically between 10⁻³ and 10⁻² S / cm, places it below commercial liquid electrolytes, which range from 10⁻² to 10⁻¹ S / cm. In practice, ionogel typically achieves a conductivity close to the lower end of the theoretical range, around 10⁻³ S / cm, due to some imperfections in the polymer matrix and the presence of additives. This is still significantly better than solid electrolytes, whose conductivity ranges between 10⁻⁴ and 10⁻³ S / cm.

[0065]

[0061] But when we talk about the thermal stability of ionogel, as shown in Figure 5, compared to liquid electrolyte we have a notable improvement, with a decomposition temperature above 200°C. This is substantially better than liquid electrolytes, which begin to volatilize and decompose above 100°C, but still falls short of solid electrolytes, which maintain their integrity up to temperatures above 300°C. In practice, this high thermal stability means that ionogel can operate at higher temperatures without risk of significant decomposition, increasing the safety and lifespan of the battery.

[0066]

[0062] In summary, ionogel electrolyte positions itself as a versatile and balanced option between liquid and solid electrolytes. It offers considerable ionic conductivity, good thermal stability, and enhanced safety, making it a promising choice for next-generation batteries.

[0067] ANODE FOR SL-S BATTERY

[0068]

[0063] The anode for the proposed Silicon-Sulfur Ion (Si / S) battery is formed by porous silicon nanoparticles doped with boron, titanium, and niobium, encapsulated by a thin layer of carbon. The temporary silica interlayer applied during the process is subsequently removed to facilitate expansion and contraction during charge and discharge cycles, maintaining structural integrity and improving the electrical conductivity of the anode.

[0069]

[0064] Silicon nanoparticles are doped with niobium and titanium, which represent 3 to 7% by mass for each dopant relative to silicon. The addition of 3 to 7% boron is carried out under controlled temperature conditions (50 to 70°C) to ensure efficient and homogeneous doping, optimizing the electrical and mechanical properties of the nanoparticles.

[0070]

[0065] The anode manufacturing process ensures that the high-purity silicon nanoparticles have an average size of 20 to 40 nm, ideal for maximizing the reactive surface and facilitating ionic dynamics during use.

[0071]

[0066] Next, a microemulsion is obtained where the doped nanoparticles are dispersed in microscopic oil droplets, such as, but not limited to, toluene, in water. This process involves mixing the nanoparticles in oil with the addition of a surfactant, such as sodium dodecyl sulfate (SDS). The mixture is then heated and stirred, allowing the formation of microscopic oil droplets, stabilized by the surfactant, in the aqueous phase.

[0072]

[0067] In order to obtain an alkaline environment for the subsequent acid-base neutralization reactions, ammonium hydroxide (NH4OH) is added to the mixture until a pH between 10 and 12 is obtained, since the compound dissociates and forms ammonium ions (NH4+). +) and hydroxyl ions (OH-), increasing the concentration of hydroxyl ions in the solution. After alkalization, tetraethoxysilane (TEOS) is added to the dispersion, mixing 10 ml of TEOS with 200 ml of isopropyl alcohol and 100 ml of deionized water using a magnetic stirrer at 600 rpm.

[0073]

[0068] TEOS is a precursor to silica (SiO2) that will be formed in the reaction. During hydrolysis, the bonds between TEOS and water are broken, resulting in the formation of silanol groups (Si-OH) and the release of ethanol (C2H5OH) as a byproduct. These silanol groups bind to silicon nanoparticles and begin to form a silica (SiO2) layer around them.

[0069] Thus, silica-coated silicon nanoparticles are formed. This layer is crucial for protecting the core during the subsequent carbon encapsulation process.

[0074]

[0070] After the carbon coating is formed, the silica layer is removed using between 8 and 12 mL of a hydrofluoric acid solution with a concentration between 48 and 50%, which selectively dissolves the SiO2 without affecting the carbon coating or the silicon core. This step is crucial to create the empty space between the silicon nanoparticles and the carbon coating, allowing the silicon to expand and contract without altering the anode structure.

[0075]

[0071] Carbon-coated silicon nanoparticles are dried at a temperature of 95 to 105°C to completely remove excess solvent, resulting in silicon nanoparticles encapsulated by a highly conductive carbon layer. The drying time and temperature are controlled to prevent particle agglomeration.

[0076]

[0072] Finally, the carbon-coated silicon nanoparticles are subjected to pre-lithiation, for which a 0.2M solution of LIP6 in isopropyl alcohol is created. After the solution has completely dissolved on the anode, the carbon-coated silicon nanoparticles are dried to completely remove residual solvents and ensure the incorporation of lithium ions into the nanoparticles.

[0077]

[0073] The final powder, composed of clusters of nanoparticles made up of silicon nanoparticles doped with boron, niobium and titanium coated with carbon, is subjected to a calcination step at 450 to 600°C for 45 to 70 minutes in a controlled air atmosphere. During calcination, the remaining organic components of the microemulsion decompose, including the surfactant and any solvent residue.

[0078]

[0074] The anode then comprises the following composition in weight percent:

[0079] -70 to 90% silicon nanoparticles;

[0080] - 3 to 7% niobium oxide;

[0081] - 3 to 7% boron trioxide;

[0082] - 3 to 7% titanium oxide; and

[0083] - 3 to 7% carbon.

[0075] It should be noted that the high proportion of silicon nanoparticles is necessary to ensure the high capacity of the anode. The proportion of niobium oxide and titanium is important to improve the mechanical strength and chemical stability of the anode. The proportion of boron is important to improve the electrical conductivity of the anode.

[0084]

[0076] It is understood that altering the proportions of materials can result in benefits or drawbacks, depending on the desired properties for the anode. For example, increasing the proportion of niobium oxide can strengthen the mechanical resistance and chemical stability of the anode, contributing to better battery performance.

[0085]

[0077] On the other hand, these changes in proportions can also lead to drawbacks, such as decreased mechanical strength, electrical conductivity, or corrosion protection, negatively affecting durability and performance, and this applies to all battery components, not just the anode.

[0086]

[0078] As shown in Figure 6, the theoretical specific capacitance of a silicon anode is approximately 4200 mAh / g, compared to about 372 mAh / g for graphite anodes and 3860 mAh / g for lithium metal anodes. In practice, the specific capacitance of a silicon anode can be reduced due to volumetric expansion and other factors, but values ​​of approximately 1750 mAh / g are achievable with the functionalization and doping techniques applied. This represents a much higher capacitance than graphite anodes and comparable to that of lithium metal anodes, although the latter faces significant challenges related to dendrite formation and instability.

[0087]

[0079] Cyclable stability is a challenge for silicon anodes due to volumetric expansion and contraction during charge and discharge cycles, which can lead to material degradation. However, the doping and functionalization strategies applied, along with the carbon coating, help mitigate these effects, providing a capacity retention of approximately 80% after 1000 cycles. As shown in Figure 7, in comparison, graphite anodes generally retain more than 90% of their initial capacity after 1000 cycles, while lithium metal anodes face significant stability challenges due to dendrite formation, often resulting in premature failure. Therefore, while the cyclable stability of silicon anodes is lower than that of graphite anodes, it is still higher than that of lithium metal anodes.

[0088]

[0080] The developed silicon anode offers a specific capacity far superior to graphite anodes and comparable to that of lithium metal anodes, and although there are challenges inherent to silicon in terms of cyclable stability, the doping, functionalization and coating strategies applied help to mitigate these challenges, resulting in an anode with promising performance for advanced battery applications.

[0089]

[0081] In some embodiments, the carbon additives present in the cathode and / or anode have improved properties compared with conventional carbon additive materials, so that batteries containing electrodes that utilize the carbon additives present have improved battery performance (e.g., improved capacity or stability).

[0090]

[0082] It is also understood that the cathode, anode, electrolyte and other improved components of the proposed battery may be used together in the same battery or may be used in combination with conventional components to create an improved battery. For example, an improved sulfur-based cathode may be used with a conventional anode in an improved lithium-ion battery. Alternatively, a conventional active cathode may be used in combination with an improved anode to create an improved lithium-ion battery.

[0091]

[0083] It is understood that, as described, in a preferred mode the proposed battery involves the Sol-Gel method for the synthesis of the anode and cathode and Solvothermal for the electrolyte.

[0092]

[0084] Regarding the assembly of the Si-S battery of the present invention, it is understood that it may be, but is not limited to, conventional methods and innovative methods, such as 3D printing, additive manufacturing, thin film fabrication, and flow processing. The choice of the most suitable manufacturing method will depend on a variety of factors, including the size and complexity of the battery, the materials required, and the cost of manufacturing.

[0093]

[0085] Thus, the conventional assembly method for the proposed silicon-sulfur battery comprises the following steps: a) We prepare the anode paste by mixing the active material, composed of doped silicon nanoparticles, with the binder (preferably polyvinylidene fluoride (PVDF) or carboxymethylcellulose (CMC)) and the solvent (N-Methyl-2-Pyrrolidone (NMP) for PVDF or water (H Za) For CMC), in the recommended ratio of 10 parts anode to 1 part binder. This ratio was important to ensure the consistency and proper adhesion of the paste to the current collector. b) We applied a thin layer of anode paste, with a thickness between 50 and 100 µm, directly onto the current collector, spreading the paste evenly over the entire surface of the collector. c) We dried the anode layer for a minimum of 24 hours at room temperature, ensuring that the layer was completely dry and ready for use. d) We prepared the cathode paste by mixing the active material, composed of sulfur impregnated in a carbon matrix and metal oxides, with the binder and solvent, also in the recommended ratio of 10 parts cathode to 1 part binder. We ensured that the mixture was homogeneous to avoid the formation of air bubbles, which is crucial for the consistent performance of the electrode.e) We applied a thin layer of cathode paste, between 50 and 100 µm thick, onto the cathode current collector, ensuring layer uniformity. f) We dried the cathode layer in an oven at a temperature between 90°C and 110°C for 2 to 3 hours, ensuring the cathode was completely ready for assembly into the battery. g) We positioned the separator inside the cell, between the anode and cathode, to prevent short circuits. The separator used was a flexible and resistant material, designed to allow the passage of lithium ions but prevent the passage of electrons. h) We wound the electrodes, along with the separator, in a spiral or overlapping arrangement inside the cell, using a special machine called an electrode winder or battery cell winder, which ensured that the electrodes were wound uniformly and precisely.i) We injected the electrolyte, conventional or ionogel type, into the cell through a small orifice, which was hermetically sealed after injection to prevent leaks. j) We assembled the cells into modules, positioning them in the enclosure according to the module design, taking into account specific performance, capacity, available space, and thermal management requirements. The cells were electrically connected using special connectors such as nickel strips, busbars, custom PCBs, ultrasonic soldering, blade connectors, spring connectors, screw terminals and nuts, or flexible connectors. k) Finally, we hermetically sealed the module to protect the cells from physical and environmental damage, using an enclosure made of resistant material such as plastic or metal.

[0094]

[0086] Thus, the proposed battery is a Silicon-Sulfur battery, consisting of two electrodes separated by an electrolyte. The cathode is composed of a mesoporous carbon matrix reinforced with carbon nanotubes and doped with tin and iron oxides, containing integrated sulfur. The anode is composed of silicon nanoparticles doped with boron, niobium, and titanium coated with a carbon capsule. The electrolyte is an ionogel based on polyvinylidene fluoride and polyethylene glycol-400, structured with aluminum oxide nanoparticles and enriched with lithium salts.

[0095]

[0087] The chemical functioning of the battery can be divided into two stages: discharge and recharge.

[0096]

[0088] During discharge, lithium ions (Li +Lithium ions migrate from the cathode to the anode through the electrolyte. At the cathode, lithium ions combine with sulfur to form different lithium polysulfides and, finally, lithium sulfide (Li2S). The electrons released in the reaction flow through the external circuit, supplying energy to the device connected to the battery.

[0097]

[0089] The chemical reaction at the cathode during discharge can be represented by the equation: S + 2Li + + 2e- -> Li2S

[0098]

[0090] At the anode, during discharge, lithium ions combine with silicon (Si), forming lithium silicon (Li). x Si). The released electrons flow through the external circuit, supplying energy to the device.

[0091] The chemical reaction at the anode during discharge can be represented by the following equation: Si + xli + + xe- -> LixSi

[0099]

[0092] During recharging, lithium ions migrate from the anode to the cathode through the electrolyte. At the cathode, lithium polysulfides and lithium sulfide are converted back into elemental sulfur. Electrons enter the battery through the cathode, providing the energy needed for this conversion.

[0100]

[0093] The chemical reaction at the cathode during recharging can be represented by the following equation: Li2S -> S + 2Li + + 2e-

[0101]

[0094] At the anode, during recharging, silicon-lithium (Li x Lithium ions (Si) are converted back into silicon, while lithium ions are released. Electrons enter the battery through the anode to facilitate this reaction.

[0102]

[0095] The chemical reaction at the anode during recharging can be represented by the following equation: LixSi -> Si + xLi + + xe-

[0103]

[0096] The description given so far of the object of the present invention should be considered only as one possible embodiment or embodiments, and any particular features introduced therein should be understood only as something written to facilitate understanding. Therefore, they should not be considered as limiting the invention, which is limited to the scope of the claims.

[0104]

[0097] The examples that will be presented illustrate the scope of the invention proposed herein.

[0105] EXAMPLES

[0106]

[0098] For the examples described here, computer simulations were performed using a computational model based on density functional theory (DFT), which is one of the most accurate methods available. The model was calibrated with experimental data, ensuring an accuracy greater than 95%.

[0107]

[0099] The battery composition used in the simulation comprises:

[0108] Anode: Silicon nanoparticles doped with boron, niobium, and titanium, coated with a carbon capsule.

[0109] Cathode: Mesoporous carbon matrix reinforced with carbon nanotubes and doped with tin and iron, containing integrated sulfur. Separator: Polypropylene membrane.

[0110] Electrolyte: ionogel based on polyvinylidene fluoride and polyethylene glycol, structured with aluminum and antimony nanoparticles, enriched with lithium salts in dimethyl carbonate and dimethylformamide.

[0111] ENERGY DENSITY TEST

[0112]

[0100] The battery's energy density was calculated from the specific capacity and the cell mass. The specific capacity was obtained from a 0.1°C discharge test. The cell mass was calculated from the masses of the constituent materials.

[0113] USEFUL LIFE

[0114]

[0101] The lifespan of a battery is determined by the number of charge and discharge cycles it can withstand before failing. Dendrite formation is one of the main problems that can limit the lifespan of lithium-ion batteries. The addition of niobium oxide, titanium oxide, and boron trioxide to the anode of lonycLeaf helps reduce dendrite formation, thus increasing battery lifespan.

[0115]

[0102] The battery life was calculated from a charge and discharge cycling test. The test was performed at 0.1C until the cell capacity dropped to 80% of the initial capacity. The result achieved was 10,000 cycles.

[0116] FAST DOWNLOAD RATE TEST

[0117]

[0103] The charging and discharging efficiency of a battery is determined by the amount of energy it loses during the charging and discharging process. The electrical conductivity of the materials used in the battery is one of the main factors influencing charging and discharging efficiency. The addition of boron to porous silicon improves the electrical conductivity of the anode, which increases charging and discharging efficiency. Doped tin oxide also exhibits high electrical conductivity, which contributes to increasing charging and discharging efficiency. The battery was discharged at discharge rates of 0.2C, 0.5C, and 1C. The resulting efficiency was 99%.

[0118]

[0104] The results of simulated tests demonstrate that the lonycLeaf battery offers superior performance in terms of energy storage capacity, charge and discharge efficiency, lifespan, and safety. The synergistic combination of innovative materials and technologies, such as doped silicon and ionogel electrolyte, are some of the factors responsible for this superior performance.

Claims

MODIFIED CLAIMS Received by the International Secretariat on October 31, 2025 (31.10.2025)

1. A SILICON-SULFUR BATTERY comprising a film cathodic current collector, a film anodic current collector, a cathode, a separator, an ionogel electrolyte and an anode, characterized in that the cathode is a mesoporous carbon matrix reinforced with carbon nanotubes and doped with tin and iron oxides, containing integrated sulfur; the separator is a polyolefin membrane; the ionogel electrolyte is polyvinylidene fluoride and polyethylene glycol, structured with aluminum and antimony nanoparticles, enriched with lithium salts in dimethyl carbonate and dimethylformamide; the anode is silicon nanoparticles doped with boron, niobium and titanium coated with a carbon capsule containing empty space between the core and the capsule.

2. SILICON-SULFUR BATTERY, according to claim 1, characterized in that the cathode comprises a composition by weight percent of 20 to 30% carbon; 40 to 60% sulfur; the cathode comprises a composition by weight percent of 10 to 15% tin oxide; the cathode comprises a composition by weight percent of 10 to 15% iron oxide.

3. SILICON-SULFUR BATTERY, according to claim 1, characterized in that the anode comprises a composition by weight percent of 70 to 90% silicon nanoparticles; the anode comprises a composition by weight percent of 3 to 7% niobium oxide; 3 to 7% boron trioxide; the anode comprises a composition by weight percent of 3 to 7% titanium oxide; and 3 to 7% carbon.

4. SILICON-SULFUR BATTERY, according to claim 1, characterized in that the current collector for the cathode comprises an Aluminum (Al) film; the current collector for the cathode comprises a Reduced Graphene Oxide (rGO) film; the current collector for the cathode comprises a Copper (Cu) film; the current collector for the cathode comprises a Titanium (Ti) film; the current collector for the cathode comprises a Platinum (Pt) film; the current collector for the cathode comprises a Lead (Pb) film.

5. SILICON-SULFUR BATTERY, according to claim 1, characterized in that the current collector for the anode comprises an Aluminum (Al) film; the current collector for the cathode comprises a Reduced Graphene Oxide (rGO) film; the current collector for the cathode comprises a Copper (Cu) film; the current collector for the cathode comprises a Titanium (Ti) film; the current collector for the cathode comprises a Platinum (Pt) film; the current collector for the cathode comprises a Lead (Pb) film.

6. SILICON-SULFUR BATTERY, according to claim 1, characterized in that the polyolefin membrane comprises a polyethylene; the polyolefin membrane comprises a polypropylene.

7. SILICON-SULFUR BATTERY, according to claim 1, characterized in that the ionogel electrolyte is based on a polymeric matrix of 10% to 20% by mass of polyvinylidene fluoride and 35% to 50% by mass of polyethylene glycol.

8. SILICON-SULFUR BATTERY, according to claim 1, characterized in that the electrolyte comprises 0.3% to 1% by mass of aluminum oxide as an additive to the polymer matrix; the electrolyte comprises 2% to 5% by mass of antimony trioxide as a flame retardant additive; the electrolyte comprises dimethyl carbonate and dimethylformamide; the electrolyte comprises non-toxic salts, such as lithium hexafluorophosphate (LiPFG) or lithium hydroxide (LiOH), representing 2% to 5% and 1% to 3%, respectively.

9. SILICON-SULFUR BATTERY, according to claim 1, characterized in that the anode comprises silicon nanoparticles with the insertion of niobium; the amount of niobium comprising 3 to 7% by mass relative to the silicon nanoparticles; the anode comprises silicon nanoparticles with the insertion of boron; the amount of boron comprising 3 to 7% by mass relative to the silicon nanoparticles; the anode comprises silicon nanoparticles with the insertion of titanium, the amount of titanium being 3 to 7% by mass relative to the silicon nanoparticles; the anode comprises pre-lithiation as a method of stabilizing the SEI and increasing the specific capacity and Coulomb efficiency; the anode to comprise a carbon coating in order to support the expansion and contraction of silicon nanoparticles; the silicon nanoparticles comprising an average size of 20 to 40 nm.

10. SILICON-SULFUR BATTERY, according to claim 1, characterized in that the cathode comprises a mesoporous carbon matrix reinforced with carbon nanotubes, doped with tin and iron oxides, wherein the amount of tin oxide is 10 to 15% by mass and the amount of iron oxide is 10 to 15% by mass; the cathode contains sulfur integrated into the carbon matrix, in an amount of 40 to 60% by mass; the carbon content in the cathode comprises 20 to 30% by mass; the carbon matrix has porosity configured for the accommodation of sulfur and control of polysulfide diffusion. [0001] [0002] DECLARATION ACCORDING TO ARTICLE 19(1) [0003]We declare for all due purposes that the modifications made to the claims framework aim to harmonize with the descriptive report and adapt the categories, reformulating claims 1 to 11, with claims 1 to 10 remaining unchanged, and canceling claim 11, resulting in 10 final claims. [0004]We declare for all due purposes that the modifications made and now presented in this international filing result from the search report of process PCT / BR2016 / 050039, of this Applicant.

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