Silicon-based battery

Abstract

The silicon-based battery comprises a positive electrode, a negative electrode and an electrolyte, the negative electrode comprises a negative electrode current collector and a negative electrode active substance layer arranged on at least one side of the negative electrode current collector, the negative electrode active substance layer comprises a negative electrode active substance, the negative electrode active substance comprises a silicon material, the particle size of the silicon material is W [mu] m, and the particle size of the silicon material is W [mu] m. The electrolyte comprises a first additive and a second additive, the first additive comprises a phenyl silane compound, the mass percentage content of the first additive in the electrolyte is A%, the second additive comprises an acrylate compound, and the mass percentage content of the second additive in the electrolyte is B%; and the silicon-based battery satisfies 0.3 < = W / (A + B) < = 11, 0.15 < = A / B < = 5.5, A is 0.5-4, B is 0.5-4, and W is 3-15. According to the scheme provided by the invention, dynamic balance between low-temperature dynamics and high-temperature stability can be realized through a synergistic film forming mechanism of the phenyl silane compound and the acrylate compound and particle size optimization of the silicon material.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to silicon-based batteries. Background Art

[0002] Silicon anode materials for lithium-ion batteries offer high specific capacity, but their volume expansion leads to structural pulverization and failure. At low temperatures, lithium-ion diffusion is hindered, causing a sharp drop in rate performance. At high temperatures, the SEI membrane repeatedly ruptures and regenerates, causing cycling capacity decay. Furthermore, side reactions such as gas production degrade storage performance, severely restricting the practical application of lithium-ion batteries.

[0003] Related technologies improve lithium battery performance by changing the particle size of the silicon material in the silicon anode material. For example, reducing the silicon material particle size can shorten the lithium ion diffusion path and significantly reduce the diffusion impedance, which is beneficial for improving fast charging performance and low-temperature rate performance; increasing the silicon material particle size can reduce side reactions.

[0004] However, the reduction in the particle size of silicon materials will lead to continuous reconstruction of the SEI film and electrolyte consumption during high-temperature cycling and storage, accelerating capacity decay; the increase in the particle size of silicon materials will extend the lithium ion diffusion path, resulting in increased interfacial impedance, which will restrict low-temperature performance.

[0005] Therefore, how to break through the technical bottleneck of "small-size silicon sacrifices high-temperature performance, and large-size silicon sacrifices low-temperature performance" in silicon-based batteries is an urgent problem to be solved. Summary of the Invention

[0006] In order to solve or partially solve the problems existing in the related art, the present application provides a silicon-based battery that can achieve a dynamic balance between low-temperature dynamics and high-temperature stability through the synergistic film-forming mechanism of phenylsilane compounds and acrylate compounds and the optimization of the particle size of silicon materials.

[0007] In a first aspect, the present application provides a silicon-based battery, comprising a positive electrode, a negative electrode, and an electrolyte. The negative electrode comprises a negative electrode current collector, and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. The negative electrode active material layer comprises a negative electrode active material, the negative electrode active material comprises a silicon material, and the particle size of the silicon material is W μm. The electrolyte comprises a first additive and a second additive, the first additive comprises a phenylsilane compound, and the mass percentage of the first additive in the electrolyte is A%; the second additive comprises an acrylate compound, and the mass percentage of the second additive in the electrolyte is B%. Furthermore, the silicon-based battery satisfies the following relationship: 0.3≤W / (A+B)≤11 0.15≤A / B≤5.5 Among them, A is 0.5~4, B is 0.5~4, and W is 3~15.

[0008] As an optional embodiment, the silicon-based battery satisfies the following relationship: 1.4≤W / (A+B)≤7.5.

[0009] As an optional embodiment, A is 1-4.

[0010] As an optional embodiment, B is 1-4.

[0011] As an optional embodiment, W is 5-10.

[0012] As an optional embodiment, the first additive includes at least one of the following compounds:

[0013] Structural formula 1

[0014] Structural Formula 2

[0015] Structural formula 3 Here, R1 to R9 are each independently selected from an alkyl group having 1 to 6 carbon atoms and substituted or unsubstituted by halogen.

[0016] As an optional embodiment, the first additive includes at least one of the following compounds:

[0017] Compound 1

[0018] Compound 2

[0019] Compound 3.

[0020] As an optional embodiment, the second additive includes at least one of the compounds represented by Structural Formula 4 and Structural Formula 5:

[0021] Structural Formula 4

[0022] Structural Formula 5 wherein X1 and X2 are each independently selected from an alkoxy group having 1 to 10 carbon atoms and 1 to 6 oxygen atoms, which may be substituted or unsubstituted by halogen.

[0023] As an optional embodiment, the second additive includes at least one of the following compounds:

[0024] Compound a

[0025] Compound b

[0026] Compound c.

[0027] As an optional embodiment, the electrolyte further includes a third additive, and the third additive includes a carbonate compound.

[0028] As an optional embodiment, the mass percentage of the third additive in the electrolyte is 0.01% to 15%.

[0029] As an optional embodiment, the carbonate compound includes at least one of fluoroethylene carbonate, vinylene carbonate, 3,3,3-trifluoropropylene carbonate, tetrafluoroethylene carbonate, and vinyl ethylene carbonate.

[0030] A second aspect of the present application provides an electronic device comprising the aforementioned silicon-based battery.

[0031] The technical solution provided by this application may include the following beneficial results: This application establishes a balance between material properties and interface behavior by precisely controlling the particle size of the silicon material and the mass ratio of the first additive and the second additive. When 0.3≤W / (A+B)≤11, and 0.15≤A / B≤5.5, and simultaneously controlling A to 0.5~4, B to 0.5~4, and W to 3~15, the synergistic effect of the additives can form a dynamic self-regulating interface system: it can not only alleviate the mechanical stress concentration caused by the volume expansion of the silicon material and inhibit damage to the electrode microstructure; it can also maintain moderate transmission performance of the electrolyte through viscoelastic properties. This synergistic effect achieves compatibility between interface stability and ion transmission efficiency under wide temperature conditions, ensuring rapid charge transfer under low-temperature conditions while effectively inhibiting interface degradation in high-temperature environments, achieving a dynamic balance between low-temperature dynamics and high-temperature stability.

[0032] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. DETAILED DESCRIPTION

[0033] The embodiments of the present application will be described in more detail below. It should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0034] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. As used in this application and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0035] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0036] In related technologies, lithium battery performance is improved by changing the particle size of the silicon material in the silicon negative electrode material. For example, reducing the silicon material's particle size can shorten the lithium ion diffusion path, significantly reducing the diffusion impedance, which is beneficial for improving fast charging performance and low-temperature rate performance; increasing the silicon material's particle size can reduce side reactions. However, reducing the silicon material's particle size will lead to continuous reconstruction of the SEI film and electrolyte consumption during high-temperature cycling and storage, accelerating capacity decay; increasing the silicon material's particle size will extend the lithium ion diffusion path, resulting in increased interfacial impedance and restricting low-temperature performance.

[0037] To address the above problems, an embodiment of the present application provides a silicon-based battery that can achieve a dynamic balance between low-temperature dynamics and high-temperature stability through the synergistic film-forming mechanism of phenylsilane compounds and acrylate compounds and the optimization of the particle size of silicon materials.

[0038] An embodiment of the present application provides a silicon-based battery, comprising a positive electrode, a negative electrode, and an electrolyte. The negative electrode comprises a negative electrode current collector, and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. The negative electrode active material layer comprises a negative electrode active material, the negative electrode active material comprises a silicon material, and the particle size of the silicon material is W μm. The electrolyte comprises a first additive and a second additive, the first additive comprises a phenylsilane compound, and the mass percentage of the first additive in the electrolyte is A; the second additive comprises an acrylate compound, and the mass percentage of the second additive in the electrolyte is B; and the silicon-based battery satisfies the following relationship: 0.3≤W / (A+B)≤11 Formula (1) 0.15≤A / B≤5.5 Formula (2) Among them, A is 0.5~4, B is 0.5~4, and W is 3~15.

[0039] In the embodiments of the present application, the particle size of the silicon material may be the volume median particle size Dv50. The volume median particle size Dv50 represents the median value of the volume distribution of the powder particles and is determined by particle size analysis techniques such as laser diffraction. It represents the middle threshold of the particle size distribution in the particle system: 50% of the total volume is composed of particles smaller than this value, and the remaining 50% corresponds to particles of larger size.

[0040] In the examples of this application, the particle size of the silicon material represents the overall particle size of the silicon material and is directly related to the lithium ion transport properties within the material. Reducing the silicon material particle size increases the particle specific surface area, shortens the lithium ion migration path, and reduces diffusion impedance. It also simultaneously improves lithium ion diffusion efficiency and increases interfacial active sites. From a material dynamics perspective, a lower particle size can optimize the Li+ transport pathway, enhancing the electrode's rapid charge and discharge capabilities, particularly effectively improving rate performance in low-temperature applications. However, a high specific surface area exacerbates side reactions at the silicon-electrolyte interface, leading to continuous thickening of the SEI film under high-temperature conditions, which in turn accelerates capacity decay and reduces storage stability. Conversely, increasing the silicon material particle size reduces side reactions, but also lengthens the lithium ion diffusion path, increases interfacial impedance, and restricts low-temperature performance. Therefore, to address the conflicting issues between high-temperature cycling and low-temperature performance caused by changes in silicon particle size in silicon-based batteries, it is necessary to precisely control the silicon material particle size parameters to establish an optimal balance between fast-charging performance and cycling durability.

[0041] To address these challenges, the phenylsilane compounds and acrylate compounds provided in the present invention achieve synergistic effects through functional group complementarity and dynamic equilibrium, effectively overcoming the mutually exclusive challenges of high-temperature cycling and low-temperature performance in silicon-based batteries. The core functionality of phenylsilane compounds stems from the synergistic effect between the benzene ring and the silane group (Si-O). The π-electron system of the benzene ring significantly enhances electrolyte wettability of the silicon anode, reduces interfacial contact resistance, and lowers interfacial impedance by optimizing lithium ion diffusion pathways. The silane group preferentially adsorbs on the silicon surface and, through in situ electrochemical polymerization, forms a flexible Si-O-C cross-linked film. This cross-linked film is tightly bonded to the silicon substrate via Si-O-Si chemical bonds, forming a SEI membrane that is both ionically conductive and mechanically flexible. This SEI membrane effectively buffers silicon volume expansion and significantly inhibits electrolyte decomposition by removing water and acid. However, the benzene rings of phenylsilane compounds are susceptible to oxidative side reactions with the electrolyte at high temperatures, leading to localized depolymerization of the SEI film. Furthermore, the flexible film lacks mechanical strength, making it difficult to suppress the dramatic volume expansion of silicon particles during long-term cycling. In systems with low-particle size and high surface area, gas generation and thickness expansion during high-temperature storage are particularly prominent. Acrylate compounds, however, precisely compensate for these deficiencies through the high-temperature responsiveness of oxygen-containing groups (e.g., ether bonds). The acrylate functional groups preferentially polymerize at high temperatures to form a three-dimensional cross-linked network, further reducing the volume expansion of the silicon material through physical encapsulation and mechanical anchoring. The dynamic flexibility of the oxygen-containing groups provides stress relief for the SEI film, while the highly polar oxygen-containing groups promote dense and uniform SEI film formation and enhance the electrolyte solvent oxidation potential through electron-withdrawing effects. However, the resulting three-dimensional cross-linked network exhibits increased interfacial impedance at low temperatures due to a significant viscosity increase, severely limiting low-temperature performance. This deterioration in interfacial dynamics is particularly pronounced in systems with long diffusion paths for high-particle size silicon particles. These two types of additives can achieve the following performance optimizations through complementary functions and optimized coordination with the silicon material particle size.

[0042] On the one hand, the two types of additives can achieve synergy through functional complementarity and dynamic balance: 1) Interface wetting optimization: The benzene ring of phenylsilane compounds can improve the uniformity of electrolyte distribution, transforming the low-temperature viscosity disadvantage of acrylate compounds into a uniform interface contact advantage; 2) SEI membrane structure innovation: The flexible Si-OC layer of phenylsilane compounds and the rigid COC layer of acrylate compounds can form a "rigid-flexible composite" interface. The former ensures dynamics through low-impedance ion channels, while the latter inhibits high-temperature expansion through a three-dimensional network; 3) Chemical stability synergy: Phenylsilane compounds can continuously scavenge acidic substances, protecting the three-dimensional cross-linked network membrane formed by acrylate compounds from acid corrosion. At the same time, the electron-withdrawing effect of acrylate compounds can inhibit the oxidation of benzene rings and reduce high-temperature gas production. Therefore, the synergistic mechanism of the two innovatively constructs a dynamic interface system that adapts to temperature changes, inhibiting high-temperature SEI rupture and gas production, and improving cycling stability.

[0043] On the other hand, for low-particle silicon particles, the wetting effect and flexible film-forming properties of phenylsilane compounds can reduce the side reaction activity caused by the high specific surface area. Furthermore, the three-dimensional rigid network formed by acrylate compounds can inhibit expansion through high-temperature anchoring. These two factors work together to significantly improve the high-temperature cycling performance of low-particle silicon systems. For high-particle silicon particles, phenylsilane compounds can shorten the lithium ion diffusion path by enhancing interfacial wetting, compensating for the kinetic defects of large particles. Furthermore, the electron-withdrawing effect of acrylate compounds can inhibit high-temperature side reactions, significantly improving the high-temperature storage performance of high-particle silicon systems.

[0044] Based on the above, the applicants discovered that by regulating the ratio (W) of the silicon particle size to the combined mass of the two additives (A+B), or W / (A+B), a "rigid-flexible composite" SEI membrane can be constructed at the molecular scale: the flexible Si-OC layer of phenylsilane preferentially covers the recessed areas of the silicon particle surface, optimizing ion transport channels; the rigid COC network of acrylate coats the raised areas of the particles, inhibiting volume expansion through a cross-linked structure. This composite membrane combines high ionic conductivity with compressive strength. Furthermore, in terms of chemical stability, the acid-scavenging function of phenylsilane removes HF from the electrolyte, protecting the acrylate membrane from acid corrosion, while the electron-withdrawing effect of acrylate inhibits high-temperature oxidation of the benzene ring, reducing the risk of SEI membrane depolymerization, forming a bidirectional protective mechanism. The core innovation of this synergistic mechanism lies in the deep coupling of the size effect of silicon particles with the properties of the functional groups of two types of additives. By matching the particle size of the silicon particles to the total mass of the two types of additives, phenylsilanes are used to inhibit side reactions and acrylates to inhibit expansion in low-particle silicon systems. In high-particle silicon systems, phenylsilanes are used to optimize wetting and acrylates to block side reactions. These three factors work together to create a dynamic equilibrium system, simultaneously improving the battery's high-temperature storage, high-temperature cycle life, and low-temperature discharge / charge performance.

[0045] In the present embodiment, when W / (A+B) is less than 0.3, the system faces a dual risk of failure: First, excessive additives significantly increase electrolyte viscosity, hindering lithium ion transport kinetics and significantly degrading low-temperature charging performance. Second, the small silicon particle size leads to a dramatic increase in specific surface area, exacerbating side reactions at the electrode-electrolyte interface and causing uncontrolled thickening of the SEI film. Simultaneously, excessive additives fail to effectively suppress these side reactions, leading to severe degradation of high-temperature cycling stability. When W / (A+B) exceeds 11, the opposite drawbacks emerge: First, the excessively large silicon material leads to an excessively long lithium ion diffusion path, significantly limiting low-temperature charging capability. Second, insufficient additives make it difficult to construct a composite SEI film with synergistic mechano-chemical protection. At high temperatures, the rapid expansion of silicon causes interfacial structural damage, accelerating capacity fading and gassing. Therefore, the present embodiment achieves a balance between material properties and interfacial behavior by precisely controlling the silicon particle size and the mass ratio of the first and second additives. When 0.3 ≤ W / (A+B) ≤ 11, the synergistic effect of the additives creates a dynamically self-regulating interface system: it mitigates mechanical stress concentration caused by silicon material volume expansion, inhibiting electrode microstructural damage, while also maintaining moderate electrolyte transport performance through viscoelastic regulation. This synergistic effect achieves compatibility between interface stability and ion transport efficiency over a wide temperature range, ensuring rapid charge transfer at low temperatures while effectively inhibiting interface degradation at high temperatures, achieving a dynamic balance between low-temperature dynamics and high-temperature stability.

[0046] The present embodiment also controls 0.15≤A / B≤5.5. By controlling the A / B ratio within the range of 0.15-5.5, the synergistic effect of the first additive and the second additive is more favorable, thereby improving the high-temperature cycling performance and high-temperature storage performance of the battery.

[0047] In formulas (1) and (2) of the present embodiment, A is 0.5-4. ‌ When the mass percentage A% of the first additive in the electrolyte is less than 0.5%, the mechanical strength of the SEI film formed at the negative electrode interface is significantly reduced due to insufficient film-forming components, making it unable to buffer the expansion stress of silicon particles, resulting in film rupture. At the same time, the deterioration of the interface wettability causes an increase in lithium ion transfer impedance, and the positive electrode CEI film exhibits a porous structure due to the lack of acidic substance scavenging ability. During high-temperature storage, the electrolyte continues to decompose, accelerating capacity decay, resulting in an overall decline in battery performance. When the mass percentage A% of the first additive in the electrolyte is higher than 4%, the excessive active groups will cause excessive thickening of the negative electrode SEI film, hindering lithium ion diffusion and exacerbating low-temperature charge polarization. In addition, the imbalance of the intermolecular forces leads to an abnormal increase in the viscosity of the electrolyte. At the same time, the imbalance of the rigid-flexible network ratio causes the composite SEI film's anti-expansion ability to decline, and the gas production of the positive electrode interface side reaction surges. In this state, the synergistic mechanism between the additives is destroyed, and the wide-temperature performance is simultaneously degraded. By controlling the mass percentage of the first additive in the electrolyte within an appropriate range, triple synergy can be achieved through molecular configuration and concentration matching, constructing a double-network protective layer with adaptive volume changes at the negative electrode, forming a dense passivation film at the positive electrode, and maintaining a balance between electrolyte viscosity and ion transfer efficiency.

[0048] In the embodiment of the present application, the mass percentage A% of the first additive in the electrolyte can be 0.5%, 0.8%, 1.0%, 1.3%, 1.5%, 1.7%, 2.0%, 2.4%, 2.8%, 3.0%, 3.5%, 4.0%, etc. or any value within the above-mentioned limited range, and the present application is not limited to this. When the mass percentage of the first additive in the electrolyte is controlled to be within the range of 0.5% to 4%, it can form a multi-level synergistic effect with the second additive and the silicon particles: at the negative electrode interface, the first additive optimizes the wettability of the electrolyte to the silicon particles through intermolecular forces, and its active groups react with the second additive to form a composite SEI film with both flexible and rigid characteristics. The composite SEI film can anchor the silicon matrix through chemical bonds and dynamically adapt to the volume changes of the silicon negative electrode, effectively inhibiting the side reactions between the silicon negative electrode and the electrolyte. At the positive electrode interface, the interface regulation function of the first additive and the strong polar adsorption of the second additive synergistically form a dense and stable CEI film, which simultaneously improves the high temperature cycle stability and low temperature performance of the battery.

[0049] In formula (1) and formula (2) of the present embodiment, B is 0.5-4. If the mass percentage B% of the second additive in the electrolyte is less than 0.5%, the concentration of its active groups is insufficient, which will result in a too low proportion of the rigid COC network in the negative electrode SEI film, a significant decrease in the mechanical support capacity of the film layer, and the risk of film rupture caused by the expansion of silicon particles. At the same time, the positive electrode interface is weakened due to polar adsorption, resulting in a loose CEI film structure, aggravated electrolyte oxidation and decomposition, and simultaneous attenuation of high-temperature cycle capacity retention and high-temperature storage. If the mass percentage B% of the second additive in the electrolyte is higher than 4%, the excessive oxygen-containing groups will cause excessive cross-linking of the COC rigid network in the SEI film, resulting in an abnormal increase in film thickness, hindering lithium ion diffusion and exacerbating interface polarization. In addition, its strong polarity will cause the local viscosity of the electrolyte to increase, hindering ion migration at low temperatures and significantly reducing charging efficiency. In addition, the chemical reaction balance between the high-concentration acrylate compound and the phenylsilane compound is broken, the adaptive ability of the composite SEI / CEI film is lost, and the side reactions at the positive and negative electrode interfaces are simultaneously deteriorated. By controlling the mass percentage of the second additive in the electrolyte within an appropriate range, triple regulation can be achieved through precise intermolecular coordination, forming a rigid and flexible composite SEI film at the negative electrode and a dense CEI film at the positive electrode, while maintaining a dynamic balance between the viscosity and electrochemical activity of the electrolyte system.

[0050] In the embodiment of the present application, the mass percentage B% of the second additive in the electrolyte can be 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, etc. or any value within the above-mentioned limited range, and the present application does not impose any limitation on this. When the mass percentage of the second additive in the electrolyte is controlled to be within the range of 0.5% to 4%, it can form a multi-level synergistic effect with the first additive and the silicon particles. At the negative electrode interface, the oxygen-containing active groups of the second additive react with the silane groups of the first additive to form a composite SEI film with flexible Si-OC bonds and rigid COC bonds. The film relieves the volume expansion stress of the silicon particles through a dynamic cross-linking network and strengthens the compatibility of the electrolyte and the electrode interface. At the positive electrode interface, the strong polar groups of the second additive cooperate with the acid removal function of the first additive through adsorption to construct a dense CEI film with excellent ion conductivity, and simultaneously optimize the high-temperature cycle stability and low-temperature charge and discharge kinetics of the battery.

[0051] In formula (1) of the embodiment of the present application, W is 3 to 15. ‌ If the particle size of the silicon granule material, for example, Dv50, is less than 3 μm, the excessively small particle size will cause a surge in the specific surface area of ​​the silicon granules, exacerbating the side reactions between the electrolyte and the active interface. At the same time, the nano-sized particles are prone to agglomeration during the cycle, causing local stress concentration and leading to SEI film rupture. The high surface defect density of the silicon particles at the positive electrode interface will cause uneven growth of the CEI film, accelerate the oxidation and decomposition of the electrolyte, and simultaneously worsen the high-temperature capacity decay and low-temperature polarization phenomena. If the particle size of the silicon granule material, for example, Dv50, is greater than 15 μm, the excessively large particle size will significantly reduce the lithium insertion reaction activity of the silicon particles, extend the lithium ion diffusion path, and lead to deterioration of the kinetic performance. The volume expansion stress of the micron-sized particles is concentrated, causing cracks in the composite SEI film due to insufficient mechanical strength, and the continuous penetration of the electrolyte causes the silicon matrix to pulverize. The positive electrode interface is weakened due to the synergistic effect of the silicon particles and the additives, the density of the CEI film decreases, and the high-temperature gas production and low-temperature impedance problems are aggravated. By controlling the particle size of silicon granular materials within an appropriate range, dual regulation can be achieved by matching the particle size with the interface properties, building a stress-adaptive protection mechanism at the negative electrode and forming a stable passivation layer at the positive electrode, while balancing the electrode reaction activity and structural stability.

[0052] In the embodiments of the present application, the particle size Wμm of the silicon granular material can be 3μm, 5μm, 10μm, 15μm, or any value within the above-defined range, and this application is not limited thereto. When the particle size of the silicon granular material, such as Dv50, is controlled within the range of 3μm to 15μm, it can form a multi-level synergistic effect with the phenylsilane and acrylate additives. At the negative electrode interface, the 3μm to 15μm silicon particles, through their moderate specific surface area and pore structure, not only alleviate the volume expansion stress during the lithium insertion process, but also provide uniform interface anchoring points for the composite SEI film (containing flexible Si-OC and rigid COC bonds), dynamically maintaining the integrity of the electrode structure. At the positive electrode interface, the silicon particles in this particle size range have a moderate surface defect density, synergizing the acid removal function of the phenylsilane and the strong polar adsorption of the acrylate to construct a dense CEI film with excellent ion conductivity, thereby simultaneously improving the high-temperature cycling stability and low-temperature charge and discharge kinetics of the battery.

[0053] As an optional embodiment, the silicon-based battery satisfies the following relationship: 1.4≤W / (A+B)≤7.5.

[0054] The embodiment of the present application further adjusts the ratio W / (A+B) of the particle size W of the silicon granule material to the total mass proportion (A+B) of the two types of additives to 1.4~7.5, thereby further improving the high-temperature storage, high-temperature cycle life and low-temperature discharge / charge performance of the battery.

[0055] As an optional embodiment, A is 1-4.

[0056] In the embodiments of the present application, the mass percentage A% of the first additive in the electrolyte can be 1.0%, 1.3%, 1.5%, 1.7%, 2.0%, 2.4%, 2.8%, 3.0%, 3.5%, 4.0%, or any value within the above-defined range, and this application is not limited thereto. When the mass percentage of the first additive in the electrolyte is within the range of 1% to 4%, it can synergize with the second additive and silicon particles to further improve the high-temperature cycling, high-temperature storage, and low-temperature charge and discharge performance of the battery.

[0057] As an optional embodiment, B is 1-4.

[0058] In the embodiments of the present application, the mass percentage B% of the second additive in the electrolyte can be 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, or any value within the above-defined range, and is not limited in this application. The mass percentage of the second additive in the electrolyte is within the range of 1% to 4%, and can synergize with the first additive and silicon particles to improve the high-temperature cycling, high-temperature storage, and low-temperature charge and discharge performance of the battery.

[0059] As an optional embodiment, W is 5-10.

[0060] In the embodiments of the present application, the particle size W μm of the silicon granules can be 5 μm, 8 μm, 10 μm, or any value within the above-defined range, and is not limited in this application. When the particle size of the silicon granules is within the range of 5 μm to 10 μm, the battery has better high and low temperature performance.

[0061] As an optional embodiment, the first additive includes at least one of the following compounds:

[0062] Structural formula 1

[0063] Structural Formula 2

[0064] Structural formula 3 Here, R1 to R9 are each independently selected from an alkyl group having 1 to 6 carbon atoms and substituted or unsubstituted by halogen.

[0065] In the embodiments of the present application, the first additive satisfies any one of structural formulas 1, 2 and 3, and has the same effect of synergizing with the second additive and silicon particles to improve the high-temperature cycling, high-temperature storage and low-temperature charge and discharge performance of the battery.

[0066] As a preferred embodiment, the first additive includes at least one of the following compounds:

[0067] Compound 1 Methoxydimethyl(phenyl)silane CAS number: 17881-88-8

[0068] Compound 2 Diethoxymethylphenylsilane CAS number: 775-56-4

[0069] Compound 3 Phenyltriethoxysilane CAS number: 780-69-8.

[0070] In the embodiments of the present application, the first additive is preferably of the type mentioned above, which is more conducive to improving the high-temperature cycle performance, high-temperature storage performance and low-temperature charge and discharge performance of the battery.

[0071] As an optional embodiment, the second additive includes at least one of the compounds represented by Structural Formula 4 and Structural Formula 5:

[0072] Structural Formula 4

[0073] Structural Formula 5 wherein X1 and X2 are each independently selected from an alkoxy group having 1 to 10 carbon atoms and 1 to 6 oxygen atoms, which may be substituted or unsubstituted by halogen.

[0074] In the embodiments of the present application, the second additive satisfies any one of structural formulas 4 and 5, and has the same effect of synergizing with the first additive and silicon particles to improve the high-temperature cycling, high-temperature storage and low-temperature charge and discharge performance of the battery.

[0075] As a preferred embodiment, the second additive includes at least one of the following compounds:

[0076] Compound a 2-Methoxyethyl acrylate CAS number: 3121-61-7

[0077] Compound b Ethoxyethoxyethyl acrylate CAS number: 7328-17-8

[0078] Compound c 2-(2-methoxyethoxy)ethyl 2-methylpropenoate CAS number: 45103-58-0.

[0079] In the embodiments of the present application, the second additive is preferably of the type mentioned above, which is more conducive to improving the high-temperature cycle performance and high-temperature storage performance of the battery.

[0080] As an optional embodiment, the electrolyte further includes a third additive, and the third additive includes a carbonate compound.

[0081] In the battery system, carbonate compounds can synergistically regulate the formation of the negative electrode SEI film through directional bonding with the first additive.

[0082] As a preferred embodiment, the mass percentage of the third additive in the electrolyte is 0.01% to 15%.

[0083] In the embodiments of the present application, when the third additive comprises 0.01% to 15% by weight of the electrolyte, its functional groups can combine with the active components of the first and second additives to form a three-dimensional network structure composite SEI membrane with high mechanical strength and ion selectivity, significantly improving electrode stability and lithium ion migration efficiency, thereby extending cycle life. If the third additive comprises too much by weight of the electrolyte, the excess functional groups can cause uncontrolled electrolyte decomposition and a surge in gas production. If the third additive comprises too little by weight of the electrolyte, the interfacial film formation is incomplete, resulting in reduced reversibility of lithium deposition.

[0084] In the embodiment of the present application, the mass percentage of the third additive in the electrolyte can be 0.01%, 5%, 10%, 15%, etc. or any value within the above-mentioned limited range, and the present application does not impose any limitation on this.

[0085] As a preferred embodiment, the carbonate compound includes at least one of fluoroethylene carbonate, vinylene carbonate, 3,3,3-trifluoropropylene carbonate, tetrafluoroethylene carbonate, and vinyl ethylene carbonate.

[0086] In the embodiments of the present application, the third additive is preferably of the type mentioned above, which helps to form an interface-stabilized SEI film and improve the cycle performance of the battery.

[0087] The electrode solution of the embodiment of the present application further includes an electrolyte salt and an organic solvent.

[0088] In the embodiment of the present application, the electrolyte salt includes one or more of lithium hexafluorophosphate LiPF6, lithium difluorooxalatoborate LiODFB, lithium bis(oxalatoborate) LiBOB, lithium difluorobis(oxalatophosphate) LiDFOP, lithium tetrafluoroborate LiBF4, lithium bis(trifluoromethylsulfonyl)imide LiTFSI, lithium bis(fluorosulfonyl)imide LiFSI, and lithium difluorophosphate LiPOF2, and the concentration of the electrolyte salt can be 0.4 mol / L~2.2 mol / L.

[0089] In an embodiment of the present application, the organic solvent includes at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, diphenyl carbonate, methyl acetate, methyl propionate, methyl butyrate, methyl acetate, ethyl acetate, propyl acetate, ethyl butyrate, propyl propionate, ethyl propionate, γ-butyrolactone, 1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether.

[0090] The above-mentioned solvent types are selected to mainly dissolve the first additive, the second additive, the third additive and the lithium salt.

[0091] It should be noted that this application does not specifically limit the preparation method of the electrolyte. Those skilled in the art can prepare it into an electrolyte according to conventional technical means, for example, by uniformly mixing the raw materials according to a ratio.

[0092] In some embodiments, the positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes at least one of transition metal lithium oxide, lithium iron phosphate, lithium manganate, lithium manganese iron phosphate, and lithium vanadium phosphate. The chemical formula of the transition metal lithium oxide is Li （1+x） Ni y Co z M (1-y-z） O2, wherein -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; wherein M is selected from one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

[0093] In this application, the type of positive electrode current collector is not particularly limited and can be any known material suitable for use as a positive electrode current collector. In one embodiment, the positive electrode current collector includes a metal material such as aluminum, stainless steel, nickel plating, titanium, tantalum, and a carbon material such as carbon cloth or carbon paper. In one embodiment, the positive electrode current collector is a metal material.

[0094] In some embodiments, the positive electrode active material layer further includes a positive electrode conductor, a positive electrode binder, and a solvent.

[0095] In some embodiments, the type of the positive electrode conductive agent mentioned in this application is not limited, and any known conductive agent can be used.

[0096] In some embodiments, the positive electrode conductive agent mentioned in the present application includes at least one of carbon materials such as natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene.

[0097] In one embodiment, the type of the positive electrode binder mentioned in this application is not limited, and any known positive electrode binder can be used.

[0098] In some embodiments, the positive electrode binder includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose.

[0099] In some embodiments, the negative electrode active material is pure silicon particles.

[0100] In the present application, there is no particular limitation on the negative electrode current collector, as long as it can achieve the purpose of the present application. For example, it can be copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foam nickel, foam copper or a composite current collector.

[0101] In some preferred embodiments, the negative electrode current collector comprises copper foil.

[0102] In some embodiments, the negative electrode active material layer further includes a negative electrode conductor, a negative electrode binder, a thickener, and a solvent.

[0103] The negative electrode conductive agent includes at least one carbon material selected from natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene. The negative electrode binder includes styrene-butadiene latex, and the thickener includes CMC. The solvent includes deionized water.

[0104] In the lithium-ion battery mentioned in this application, a separator is usually provided between the positive electrode and the negative electrode to prevent short circuit. There is no particular limitation on the material and shape of the separator, as long as it does not significantly impair the effect of this application.

[0105] In some embodiments, the diaphragm includes a porous sheet or non-woven fabric-like material with excellent liquid retention, and the diaphragm includes a resin or glass fiber diaphragm material. The resin or glass fiber diaphragm material includes but is not limited to polyolefins, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, etc.

[0106] In some embodiments, the silicon-based battery may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0107] In some embodiments, the outer packaging of a silicon-based battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of a lithium-ion battery can also be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0108] The present application has no particular limitation on the shape of the silicon-based battery, which may be cylindrical, square, or any other shape.

[0109] The embodiments of the present application have no particular restrictions on the specific types of silicon-based batteries, which may be secondary batteries, power batteries, energy storage batteries, etc.

[0110] Corresponding to the aforementioned application function implementation method embodiment, the present application also provides an electronic device and corresponding embodiments.

[0111] An embodiment of the present application also provides an electronic device comprising the aforementioned silicon-based battery.

[0112] Exemplarily, the above-mentioned electrical devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0113] In order to further understand the present invention, the present application is described below in conjunction with examples. These examples are only used to illustrate the present application and are not used to limit the scope of the present application.

[0114] 1. Preparation of batteries Example 1 1. Preparation of positive electrode The positive electrode active material lithium cobalt oxide, the positive electrode conductive agent acetylene black SuperP and the positive electrode binder polyvinylidene fluoride PVDF were mixed uniformly in a mass ratio of 97:1.5:1.5, and evenly dispersed with 1-methyl-2-pyrrolidine (NMP) to prepare a uniform positive electrode slurry. The mixed slurry was coated on both sides of the aluminum foil current collector, and then baked, roll-pressed, and cut into pieces to obtain the positive electrode.

[0115] 2. Preparation of negative electrode The negative electrode active material, silicon particles, the negative electrode conductive agent, acetylene black Super P, the thickener CMC, and the negative electrode binder SBR were mixed uniformly in a mass ratio of 94:2:1.2:2.8. The mixture was then evenly dispersed in deionized water to form a uniform negative electrode slurry. The mixed slurry was then coated on both sides of the copper foil current collector, baked, roll-pressed, and cut into sheets to produce the negative electrode. The volume median particle size Dv50 (expressed in W) of the silicon particles is shown in Table 1.

[0116] 3. Preparation of electrolyte a. Ethylene carbonate EC, propylene carbonate PC, propyl propionate EP and diethyl carbonate DEC were mixed and stirred in a mass ratio of 10:20:40:30 to form a mixed solvent, and water was removed through a molecular sieve, and 1M LiPF6 was added for standby use, and mixed evenly; b. Add additives (the types and amounts of additives are shown in Table 1) to the colorless transparent liquid obtained in step a to obtain an electrolyte.

[0117] 4. Production of silicon-based batteries The prepared positive electrode sheet, separator, and negative electrode sheet are stacked in order with the separator placed between the positive and negative electrode sheets. After winding and welding the tabs, a bare battery cell is obtained. The bare battery cell is placed in an aluminum-plastic film, liquid is injected, and encapsulated to obtain a silicon-based battery.

[0118] Examples 2 to 33 and Comparative Examples 1 to 23 Examples 2 to 33 and Comparative Examples 1 to 23 are substantially the same as Example 1, with the differences being shown in Table 1.

[0119] The test method for the volume median particle size Dv50 of silicon particles is as follows: Sample particles with a concentration of 200mg / L to 300mg / L are dispersed in a liquid medium to obtain a mixture. A laser diffraction particle size analyzer (MS2000) is used to pass a monochromatic light beam through the mixture. After the light is scattered by the particles, it is distributed at different angles. The regular multi-element detector receives the values ​​of the relevant scattering pattern at many angles and records these values ​​for analysis. The scattering values ​​are calculated using the Rayleigh scattering formula to obtain the ratio of the volume of particles of each particle size level to the total volume, thereby obtaining the volume distribution of the particle size.

[0120] Table 1

[0121] 2. Performance Testing The silicon-based batteries prepared in the above-mentioned embodiments and comparative examples were subjected to the following tests.

[0122] 1. 60℃ storage performance test The silicon-based batteries prepared in the above embodiments and comparative examples were charged at a rate of 1C to a cutoff voltage and a cutoff current of 0.025C at 25°C, left to stand for 5 minutes, and the thickness H1 of the lithium-ion battery was tested; they were then stored at a temperature of 60°C for 60 days, and the thickness H2 of the lithium-ion battery was tested after the end.

[0123] Thickness expansion rate = [(H2-H1) / H1]×100%.

[0124] 2. 45℃ cycle performance test The lithium-ion batteries prepared in the above embodiments and comparative examples were charged and discharged at a rate of 1C / 1C within the charge and discharge cut-off voltage range at 45°C. The discharge capacity of the first cycle was measured as C1, and the discharge capacity of the Nth cycle was measured as C2. The capacity of the Nth cycle was divided by the capacity of the first cycle to obtain the cycle capacity retention rate R2 = C2 / C1 of the Nth cycle. The number of cycles of the lithium-ion battery when the cycle capacity retention rate R2 reached 70% was recorded.

[0125] 3. -20℃ charging capacity retention rate The lithium-ion batteries prepared in the above embodiments and comparative examples were charge-discharged three times at a rate of 1C / 1C within the charge-discharge cut-off voltage range at 25°C, and the charge capacity in the third week of the test was recorded as C3; thereafter, the lithium-ion batteries were charge-discharged three times at a rate of 1C / 1C within the charge-discharge cut-off voltage range at -20°C, and the charge capacity in the third week of the test was recorded as C4.

[0126] -20℃ charge capacity retention rate = C4 / C3×100%.

[0127] The above test results are shown in Table 2.

[0128] Table 2

[0129] According to Tables 1 and 2, a comparison of Example 2, Comparative Examples 1 to 3, and Comparative Examples 18 to 21 shows that Comparative Example 1, which lacks the first and second additives, exhibits a high thickness expansion rate, a low cycle life, and a low low-temperature charge capacity retention rate. Comparative Example 2, which incorporates only the first additive, and Comparative Example 3, which incorporates only the second additive, exhibits no significant improvement in battery performance. As shown in Example 2 and Comparative Examples 18 to 21, effective synergistic effects can only be achieved when the first and second additives are added simultaneously. Furthermore, the first additive must be a phenylsilane compound containing both phenyl and silane groups, and the second additive must be an acrylate compound containing both oxygen-containing groups (e.g., ether bonds) and acrylate groups.

[0130] According to Examples 1 to 14 and Comparative Examples 4 to 9, it can be seen that when the content of the first additive is 0.5% to 4%, the content of the second additive is 0.5% to 4%, and the particle size Dv50 of the silicon particles is 3μm to 15μm, a synergistic effect can be exerted to improve the cycle performance, high-temperature storage performance, and low-temperature charge and discharge performance of silicon-based negative electrode batteries. Further combined with the performance test data of Examples 1 to 14, it can be seen that when the content of the first additive is 1% to 4%, the content of the second additive is 1% to 4%, and the Dv50 of the silicon particles is 5μm to 10μm, it is more conducive to exerting their synergistic effect and improving battery performance.

[0131] According to Examples 1 to 33, Comparative Examples 22 and 23, it can be seen that the synergistic effect of the first additive and the second additive can be further exerted when A / B is between 0.15 and 5.5.

[0132] According to Examples 1 to 33, as well as Comparative Examples 14 and 15, when 0.3 ≤ W / (A+B) ≤ 11, the battery exhibits superior high and low temperature performance. Furthermore, according to Examples 16 to 18, and 19 to 22, when 1.4 ≤ W / (A+B) ≤ 7.5, a synergistic effect can be further exerted, further improving the battery's cycling performance, high-temperature storage performance, and low-temperature charging performance.

[0133] Comparing Examples 2, 29, and 31, the addition of the third additive facilitates the formation of an interfacially stable SEI film, improving battery performance. Further, in conjunction with Example 32, it can be seen that when the content of the third additive is 0.01% to 15%, electrode stability and lithium ion migration efficiency can be further improved, thereby extending cycle life. Further, in conjunction with Example 33, it can be seen that the carbonate compounds provided herein can further form an interfacially stable SEI film, improving battery cycle performance.

[0134] Although the present application has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for the elements thereof without departing from the scope of the present application. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present application without departing from the essential scope of the present application. Therefore, the present application is not intended to be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the present application, but rather, the present application is intended to include all embodiments falling within the scope of the appended claims.

[0135] All ranges disclosed in this application are inclusive of the endpoints, and the endpoints are combinable with each other.

[0136] The embodiments of the present application have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements to the technology in the market, or to enable other persons skilled in the art to understand the embodiments disclosed herein.

Claims

1. A silicon-based battery, characterized in that: The invention comprises a positive electrode, a negative electrode and an electrolyte, wherein the negative electrode comprises a negative electrode current collector and a negative electrode active material layer provided on at least one side of the negative electrode current collector, wherein the negative electrode active material layer comprises a negative electrode active material, wherein the negative electrode active material comprises a silicon material, and wherein the particle size of the silicon material is W μm; wherein the electrolyte comprises a first additive and a second additive, wherein the first additive comprises a phenylsilane compound, and the mass percentage of the first additive in the electrolyte is A%; and wherein the second additive comprises an acrylate compound, and the mass percentage of the second additive in the electrolyte is B%; and wherein the silicon-based battery satisfies the following relationship: 0.3≤W / (A+B)≤11 0.15≤A / B≤5.5 Among them, A is 0.5~4, B is 0.5~4, and W is 3~15.

2. The silicon-based battery according to claim 1, characterized in that The silicon-based battery satisfies the following relationship: 1.4≤W / (A+B)≤7.

5.

3. The silicon-based battery according to claim 2, characterized in that: A is 1 to 4; and / or B is 1 to 4; and / or W is 5 to 10.

4. The silicon-based battery according to claim 1, characterized in that The first additive includes at least one of the following compounds: Structural formula 1 Structural Formula 2 Structural formula 3 Here, R1 to R9 are each independently selected from an alkyl group having 1 to 6 carbon atoms and substituted or unsubstituted by halogen.

5. The silicon-based battery according to claim 4, characterized in that: The first additive includes at least one of the following compounds: Compound 1 Compound 2 Compound 3.

6. The silicon-based battery according to claim 1, characterized in that The second additive includes at least one of the compounds shown in Structural Formula 4 and Structural Formula 5: Structural Formula 4 Structural Formula 5 wherein X1 and X2 are each independently selected from an alkoxy group having 1 to 10 carbon atoms and 1 to 6 oxygen atoms, which may be substituted or unsubstituted by halogen.

7. The silicon-based battery according to claim 6, characterized in that: The second additive includes at least one of the following compounds: Compound a Compound b Compound c.

8. The silicon-based battery according to claim 1, characterized in that The electrolyte further includes a third additive, and the third additive includes a carbonate compound.

9. The silicon-based battery according to claim 8, characterized in that: The mass percentage of the third additive in the electrolyte is 0.01% to 15%.

10. The silicon-based battery according to claim 8, characterized in that: The carbonate compound includes at least one of fluoroethylene carbonate, vinylene carbonate, 3,3,3-trifluoropropylene carbonate, tetrafluoroethylene carbonate, and vinyl ethylene carbonate.

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