Battery cell, method for manufacturing the same, battery device, energy storage device, power consumption device

Abstract

The application relates to the technical field of energy storage, and provides a battery monomer, a preparation method of the battery monomer, a battery device, an energy storage device and a power utilization device. In the battery monomer, the surface of a silicon-based particle is coated with a composite layer; the composite layer comprises a passivation layer, a functional layer and a buffer layer arranged in sequence, the passivation layer comprises at least one of LiF, Li3PO4, SiO x , Li z AlO y and Al2O3; the functional layer comprises layered carbon, the layered carbon comprises at least one of graphene oxide or nitrogen-doped graphene oxide, the interlayer spacing of adjacent layered carbons is 0.4 nm to 2.5 nm, and the orientation degree of the oriented nanochannel of the layered carbon is 0.3 to 0.9; and the buffer layer comprises an elastic polymer, which at least helps to improve the problem that the silicon negative electrode interface of the battery monomer is prone to failure.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a battery cell and its preparation method, a battery device, an energy storage device, and an electrical device. Background Technology

[0002] With the rapid development of the electric vehicle industry and the increasing energy density requirements of portable electronic devices, the development of high-capacity anode materials has become a key direction for the development of lithium-ion battery technology. Silicon-based anode materials have attracted much attention due to their extremely high theoretical specific capacity, offering more than ten times the capacity advantage compared to commercial graphite anodes, and are considered key materials for realizing next-generation high-energy-density lithium-ion batteries. However, silicon undergoes a huge volume change during lithiation, and this drastic volume effect brings a series of serious technical challenges, resulting in low interfacial stability of silicon anodes.

[0003] Although there are currently solutions for modifying silicon-based anode materials, silicon anodes are still prone to interface failure after modification. Summary of the Invention

[0004] This application provides a battery cell and its preparation method, battery device, energy storage device, and power consumption device, which at least helps to improve the problem of easy failure of the silicon anode interface of the battery cell.

[0005] According to some possible embodiments of this application, a first aspect of this application provides a battery cell including a negative electrode sheet, the negative electrode sheet including a negative electrode material, the negative electrode material including silicon-based particles, the surface of the silicon-based particles being coated with a composite layer; the composite layer including a passivation layer, a functional layer and a buffer layer sequentially disposed therefrom, the passivation layer including LiF, Li3PO4, and SiO x Li z AlO y At least one of Al2O3; the functional layer includes layered carbon, which includes at least one of graphene oxide or nitrogen-doped graphene oxide, and the interlayer spacing between adjacent layered carbons is 0.4 nm to 2.5 nm, and the orientation degree of the oriented nanochannels of the layered carbon is 0.3 to 0.9; the buffer layer includes an elastic polymer.

[0006] According to some possible embodiments of this application, a second aspect of this application also provides a method for preparing a battery cell, the battery cell including a negative electrode sheet, the negative electrode sheet including a negative electrode material, the preparation of the negative electrode material including the following steps: forming a passivation layer on the surface of silicon-based particles using atomic layer deposition or precursor in-situ conversion process, the passivation layer including LiF, Li3PO4, SiO x Li z AlO yAt least one of Al2O3; a dispersion is placed on the surface of a passivation layer and then cured to form a functional layer, wherein the dispersion includes layered carbon, and the layered carbon includes at least one of graphene oxide or nitrogen-doped graphene oxide, and the curing temperature is lower than the phase transition temperature of silicon-based particles; a polymer solution is coated on the surface of the functional layer and then dried and cured at 50°C to 150°C to form a buffer layer, wherein the polymer solution includes an elastic polymer.

[0007] According to some possible embodiments of this application, a third aspect of this application also provides a battery device, including a battery cell of the first aspect, or a battery cell prepared by the method of the battery cell of the second aspect, and the battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

[0008] According to some possible embodiments of this application, a fourth aspect of this application also provides an energy storage device, including the battery device of the third aspect, the battery device being used to store electrical energy.

[0009] According to some possible embodiments of this application, the fifth aspect of this application also provides an electrical device, including the battery device of the third aspect, the battery device being used to provide electrical energy.

[0010] The technical solution provided in this application has at least the following advantages:

[0011] (1) A three-layer gradient composite interface design concept is proposed. Through the functional separation and synergy of the inner passivation layer, the middle functional layer and the outer buffer layer, the multi-scale active control of the silicon anode interface is realized.

[0012] (2) Innovatively establish a dual-parameter programmable control technology for interlayer spacing and nanochannels of layered carbon, while optimizing electron conduction and ion / solvent selective sieving functions.

[0013] (3) A triple synergistic protection mechanism of chemical passivation-selective barrier-flexible buffer was established. The inner layer reduces the nucleation overpotential and inhibits side reactions, the middle layer constructs a conductive network and diffuses stress, and the outer layer maintains the ion pathway and provides toughness adaptation. Attached Figure Description

[0014] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a process flow diagram for preparing the negative electrode material according to an embodiment of this application. Detailed Implementation

[0016] As can be seen from the background technology, although silicon anodes have good specific capacity, and although there are currently schemes to modify silicon-based anode materials, silicon anodes are still prone to interface failure after modification.

[0017] For example, graphene and its derivatives have become an important research direction due to their excellent conductivity, mechanical strength, and chemical stability. Specifically, graphene oxide (GO) can be used to encapsulate silicon anode materials. GO possesses abundant oxygen-containing functional groups and tunable conductivity; by controlling the degree of reduction, it can achieve continuous adjustment from insulation to conductivity, providing a material basis for constructing functionalized interface layers. However, existing graphene oxide methods for controlling the interface stability of silicon anodes have several limitations and technical defects, making it difficult to simultaneously meet the multiple requirements of chemical stability, ionic conductivity, and mechanical buffering, which still leads to easy interface failure of silicon anodes. The specific reasons are as follows:

[0018] The significant volume change that occurs during silicon lithiation can lead to the following problems:

[0019] First, repeated volume expansion and contraction lead to silicon particle pulverization and damage to the conductive network, resulting in a continuous deterioration of the electrical contact between the active material and the current collector. Second, the repeated rupture and reconstruction of the solid electrolyte interface film caused by volume changes not only continuously consumes electrolyte and active lithium but also generates a large number of by-reaction products, leading to increased interfacial impedance and decreased coulombic efficiency. Therefore, under the combined influence of these factors, the interface stability of the silicon anode is not high; moreover, the instability of the interface can also cause safety hazards such as local overheating and gas evolution.

[0020] Currently, the main methods for modifying silicon anode materials include carbon coating, oxide coating, and graphene encapsulation. Among these, graphene oxide encapsulation technology prepares graphene oxide using a modified Hummers method, and then encapsulates silicon nanoparticles through liquid-phase coating or spray drying. A typical process involves first preparing silicon nanoparticles, then coating them in a GO dispersion to form a Si@GO core-shell structure. To improve the conductivity of GO, reduction treatments such as heat treatment or laser annealing are typically used. For example, pulsed laser annealing uses near-infrared lasers, controlling parameters such as power density, pulse width, and frequency to partially reduce GO to balance conductivity and structural stability. During reduction, oxygen-containing functional groups in the GO layer are partially removed, and the π-conjugated structure is partially restored, thereby improving electronic conductivity. The working principle of this single-layer GO packaging structure is as follows: the GO layer acts as a conductive substrate to maintain the electron conduction path, while its flexibility adapts to the volume change of silicon and reduces the concentration of interfacial stress; the reduced rGO layer has a certain mechanical strength, which can physically constrain the expansion of silicon and reduce particle pulverization; the GO layer can also serve as part of an artificial SEI film (SEI stands for Solid Electrolyte Interphase), reducing the direct contact between the silicon surface and the electrolyte and suppressing the occurrence of side reactions.

[0021] However, the aforementioned single-layer coating strategy has many limitations and technical defects in practical applications.

[0022] First, single-layer GO packaging cannot simultaneously meet multiple functional requirements, as there is an inherent contradiction between conductivity and flexibility. While over-reduction improves conductivity, it reduces the flexibility of GO and the bonding strength with the silicon substrate, making it prone to cracking and peeling when silicon undergoes drastic volume changes. On the other hand, insufficient reduction leads to insufficient electronic conductivity, affecting the rate performance of the electrodes.

[0023] Secondly, the lack of functional separation design in single-layer structures makes it impossible to address the multiple challenges faced by silicon anodes. The requirements for chemical stability, ionic conductivity, and mechanical buffering are often contradictory, and a single GO layer struggles to find the optimal balance among these properties. For example, a thicker GO layer is needed to provide sufficient mechanical strength, but this increases ion transport impedance; while retaining more oxygen-containing functional groups is needed to improve ion conductivity, but this reduces electronic conductivity.

[0024] Third, existing technologies lack sufficient precision in controlling the interface structure and precise means of regulating key structural parameters. Key parameters such as the degree of GO reduction, interlayer spacing, and defect distribution are often difficult to control independently, leading to unpredictable interface performance and batch-to-batch variations. While traditional heat treatment or laser annealing methods can achieve reduction, their ability to regulate the microstructure is limited, making it difficult to achieve a precise balance between conductivity and selectivity. It is often difficult to simultaneously meet the multiple requirements of chemical stability, ionic conductivity, and mechanical buffering, making interface failure prone to occur under the extreme operating conditions of silicon anodes.

[0025] Based on this, this application provides a battery cell and its preparation method, a battery device, an energy storage device, and an electrical device. In the battery cell device of this application, a systematic three-layer gradient composite interface technology solution is proposed based on the principles of multi-scale interface engineering and functional separation design. This solution breaks through the design limitations of existing single-layer packaging technology, upgrading the silicon anode interface control from "passive packaging" to "active interface engineering" through the design concept of functional separation and synergy. The core technical idea of ​​this application is to construct a Si@three-layer gradient composite interface system: the inner layer is a passivation layer, which can reduce nucleation overpotential, passivate side reactions, and capture corrosive substances such as HF; the middle layer is a functional layer, which, through the dual-parameter design of controllable interlayer spacing and oriented nanochannels, provides an in-plane conductive network while selectively sieving solvents and ions and diffusing stress; the outer layer is a buffer layer, which can maintain stable ion pathways and interface wetting and achieve toughness buffering, and can also introduce trace amounts of FSI according to actual conditions. - It is an ionic liquid to enhance the ionic continuous phase.

[0026] Compared to the existing single-layer passive encapsulation approach, this application adopts an active synergistic control design concept. The three-layer structure achieves functional separation and synergy: chemical stability is mainly undertaken by the inner layer, electronic conduction and ion selectivity are handled by the middle layer, and mechanical buffering and interface adaptation are provided by the outer layer. This layered design avoids the mutual constraints between multiple functional requirements in a single-layer structure, allowing each layer to perform at its best under the most suitable conditions.

[0027] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined. Similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple pieces" refers to two or more pieces (including two pieces).

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0030] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of other elements or features. Therefore, the term "below" may cover both above and below orientation depending on the context in which the term is used, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0031] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0032] In the description of embodiments of this application, the terms "about," "approximately," "roughly," or "about" for referring to a specific parameter include numerical values, and those skilled in the art will understand that the deviation from the numerical value is within the acceptable tolerance of the specific parameter. For example, "about" or "about" for a numerical value may include additional numerical values ​​that are in the range of 90.0% to 110.0% of the numerical value, such as in the range of 95.0% to 105.0%, 97.5% to 102.5%, 99.0% to 101.0%, 99.5% to 100.5%, or 99.9% to 100.1%.

[0033] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. Furthermore, when describing a component as "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0034] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. The formation or provision of a second component above or on a first component, or on the surface of a first component, or on one side of a first component, may include embodiments where the first and second components are in direct contact, and may also include embodiments where an additional component may be present between the first and second components, thereby preventing direct contact between the first and second components. For simplicity and clarity, various components may be drawn at different scales. In the drawings, some layers / components may be omitted for simplicity. Unless otherwise specified, the formation or provision of a second component on the surface of a first component refers to direct contact between the first and second components. The term "component" may refer to a layer, film, region, portion, structure, etc.

[0035] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "component" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0036] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0037] Before describing the technical solution of this application, the following technical terms need to be defined:

[0038] "Interlayer spacing": refers to the average gap between adjacent layers of layered carbon, which is obtained based on peak position analysis of XRD (X-ray diffraction analysis) or statistics of TEM (Transmission Electron Microscope).

[0039] "Directed nanochannels": Nanoscale channel networks with statistical orientation and connectivity formed in layered carbon.

[0040] "Low thermal budget curing / reduction": refers to a curing or reduction process where the total energy or temperature-time is within a window that avoids unfavorable changes or agglomeration of the silicon core crystal phase.

[0041] "Swelling rate": The percentage change in volume of the outer polymer layer in the electrolyte.

[0042] "Adhesion strength": The bonding strength of the interlayer interface, obtained through tensile or peel tests.

[0043] "Coverage": The percentage of the inner layer covering the silicon surface, obtained through microscopic observation or elemental analysis.

[0044] The battery cell in this embodiment includes a negative electrode sheet, which contains a negative electrode material. The negative electrode material includes silicon-based particles, and the surface of the silicon-based particles is coated with a composite layer. The composite layer includes a passivation layer, a functional layer, and a buffer layer sequentially disposed therefrom. The passivation layer includes LiF, Li3PO4, and SiO2. x Li z AlO y At least one of Al2O3; the functional layer includes layered carbon, which includes at least one of graphene oxide, reduced graphene oxide (rGO) or nitrogen-doped graphene oxide, and the interlayer spacing between adjacent layered carbons is 0.4 nm to 2.5 nm, and the orientation degree of the oriented nanochannels of the layered carbon is 0.3 to 0.9; the buffer layer includes an elastic polymer.

[0045] In this embodiment, the core silicon-based particles possess extremely high theoretical specific capacity, effectively improving the energy density of the battery cell. The passivation layer includes LiF, Li3PO4, and SiO2. x Li z AlO y At least one of Al2O3, wherein "SiO" x"It is usually in the form of flakes, and its morphology and function are different from those of silicon-based particles. The value of x ranges from 0.5 to 2, preferably from 0.8 to 1.5." Li z AlO y In the formula, y and z are both positive numbers and satisfy the electroneutrality condition, i.e., z + 3 = 2y. Typical z values ​​range from 0.5 to 5.0, and y values ​​range from 1.5 to 4.0, including but not limited to common lithium aluminum oxides such as LiAlO2 and Li5AlO4. Therefore, the passivation layer can reduce the overpotential for lithium ion nucleation and promote uniform nucleation; it can also provide chemical passivation, inhibiting the direct reaction between the silicon surface and the electrolyte; and it can capture corrosive substances such as HF produced by electrolyte decomposition, protecting the silicon substrate from corrosion. The functional layer includes layered carbon, which has good conductivity, can construct an in-plane conductive network and selective barrier, and simultaneously provide stress diffusion channels. Furthermore, the inventors discovered that by controlling the interlayer spacing between adjacent layered carbons and the directional nanochannels of the layered carbons... The orientation degree can be adjusted to selectively transmit ions and solvent molecules of different sizes. In this application, by controlling the interlayer spacing to be 0.4 nm to 2.5 nm and the orientation degree of the oriented nanochannels of layered carbon to be 0.3 to 0.9, a balance between ion conduction and solvent barrier can be achieved. The buffer layer includes an elastic polymer, which has good elasticity and can provide stress buffering, interface wetting, and ion pathway maintenance functions. Therefore, in the battery cell of this application, the theoretical specific capacity of the battery cell can be improved by setting silicon-based particles, and the performance of silicon-based particles can be improved by coating the surface of silicon-based particles with a composite layer. Thus, the negative electrode in the battery cell can have good chemical stability, ion conduction, and mechanical buffering properties, making the silicon negative electrode less prone to interface failure.

[0046] The following details the structures in the negative electrode active material of this application and their possible preparation methods.

[0047] Silicon-based particles play a role in improving the negative electrode and the battery cell. Therefore, based on meeting this condition, this application does not have particular requirements regarding the specific type and particle size of the silicon-based particles. For example, silicon-based particles can be silicon, silicon-carbon composite materials, silicon-oxygen composite materials, and other high-silicon-content composite materials. The equivalent particle size range of silicon-based particles can be 50nm~1000nm, preferably 100nm~500nm, more preferably 100nm~300nm; for example, it can be 50nm, 80nm, 100nm, 200nm, 300nm, 400nm, 500nm, 700nm, 1000nm, etc., or within a range consisting of any two of the above values.

[0048] In some embodiments of this application, the thickness of the passivation layer is typically 0.5nm to 10nm, preferably 1nm to 5nm, and more preferably 1nm to 3nm. Specifically, it can be 0.5nm, 0.8nm, 1nm, 2nm, 3nm, 4nm, 5nm, 8nm, 10nm, etc., or within a range consisting of any two of the above values. If the thickness of the passivation layer is too large, it may increase the interface impedance.

[0049] The passivation layer has a coverage of 80% to 99% on the surface of silicon-based particles; preferably 85% to 95%, more preferably 90% to 95%, and specifically can be 80%, 83%, 85%, 88%, 90%, 92%, 95%, 99%, or within any range of two of the above values. Insufficient coverage or discontinuous coverage can easily lead to localized side reactions on the silicon-based particles. Therefore, when preparing the passivation layer, atomic layer deposition or precursor in-situ conversion processes are used to ensure a uniform and continuous coverage effect. Continuity and pinhole density are commonly used as quality control indicators to monitor the coverage quality of the passivation layer. These indicators can be measured and evaluated using atomic force microscopy or electrochemical leakage testing.

[0050] In some embodiments of this application, the interlayer spacing between adjacent layered carbons in the functional layer is preferably 0.5 nm to 2.0 nm, more preferably 0.7 nm to 1.5 nm; specifically, it can be 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 1.0 nm, 1.5 nm, 1.8 nm, 2.0 nm, 2.3 nm, 2.5 nm, etc., or within a range consisting of any two of the above values. Furthermore, in some embodiments of this application, the orientation degree of the oriented nanochannels of the layered carbon is preferably 0.5 to 0.8, more preferably 0.6 to 0.7; the connectivity ranges from 0.4 to 0.95, preferably 0.6 to 0.9, more preferably 0.7 to 0.85.

[0051] In addition, in some embodiments of this application, the layered carbon in the functional layer can be appropriately reduced to form reduced graphene oxide, which can improve conductivity. However, over-reduction should be avoided, as it may lead to interlayer collapse and impeded ion transport. Therefore, when preparing the functional layer, the preparation process adopts low-thermal-budget curing / reduction treatment after GO deposition, including one or more of laser treatment, flash evaporation, hot plate treatment, or chemical reduction. The reduction treatment can be performed or not, depending on actual needs. During preparation, crosslinking methods such as borate esters, polyamines, or metal coordination can be used to achieve structural fixation; insufficient crosslinking may cause cracking during cycling, which needs to be avoided in process design. In-plane conductivity, sheet resistance, interlayer spacing spectrum (obtained by statistical analysis of XRD 001 peak positions or spacing), and channel orientation (obtained by SAXS or image analysis, SAXS stands for Small Angle X-ray Scattering) can be used as key indicators to analyze the quality of the functional layer. It should be noted that the "reduced graphene oxide" in the embodiments of this application is still in an oxidized state, only the degree of oxidation is reduced.

[0052] In some embodiments of this application, the elastic modulus of the elastic polymer in the buffer layer is generally 0.1 GPa to 10 GPa. This allows the buffer layer to have good elasticity and cushioning effect, enabling it to elastically deform without cracking when the silicon undergoes volume changes. The elastic modulus is preferably 0.5 GPa to 5 GPa, more preferably 1 GPa to 3 GPa; specifically, it can be 0.1 GPa, 0.3 GPa, 0.5 GPa, 0.8 GPa, 1 GPa, 2 GPa, 3 GPa, 4 GPa, 5 GPa, 8 GPa, 10 GPa, etc., or within a range consisting of any two of the above values. To ensure the elastic modulus is within the above range, the elastic polymer includes at least one of polyvinylidene fluoride-hexafluoropropylene copolymer or polyacrylic acid.

[0053] In some embodiments of this application, the thickness of the buffer layer is typically in the range of 2nm to 50nm, preferably 5nm to 30nm, and more preferably 10nm to 20nm; specifically, it can be 2nm, 3nm, 5nm, 8nm, 10nm, 15nm, 20nm, 25nm, 30nm, 40nm, 50nm, etc., or within the range of any two of the above values.

[0054] In addition, in some embodiments of your application, the buffer layer also contains an additive liquid, and the mass content of the additive liquid is 0-15% based on the mass of the buffer layer. The additive liquid is usually an ionic liquid, including bis(fluorosulfonyl)imide anions; the mass content of the additive liquid is preferably 0-10 wt%, more preferably 0-5 wt%. Introducing an additive liquid containing bis(fluorosulfonyl)imide anions can enhance the ionic continuous phase. It can be added or not added according to actual needs. When the battery cell is sensitive to solvent compatibility or cost, it is preferable not to add an additive liquid. In addition, when introducing the additive liquid, the content of the introduced additive liquid should generally not be too high, otherwise it may lead to swelling and decreased adhesion performance.

[0055] The total porosity and compaction density of the negative electrode sheet affect the fast-charging performance, energy density, and ion transport performance of the battery cell. This application does not impose particular limitations on parameters such as the total porosity and compaction density of the negative electrode sheet; these can be adjusted according to actual needs, as long as the objectives of this application are met. For example, in some embodiments of this application, the total porosity of the negative electrode sheet is generally in the range of 30% to 70%, preferably 35% to 50%, and more preferably 40% to 45%. The compaction density of the negative electrode sheet is in the range of 1.0 g / cm³. 3 ~2.0g / cm 3 Preferred concentration: 1.2 g / cm³ 3 ~1.8g / cm 3 More preferably 1.3 g / cm 3 ~1.6g / cm 3 .

[0056] In addition, in some embodiments of this application, the effective porosity of the negative electrode sheet ranges from 20% to 65%, preferably 30% to 60%, and more preferably 35% to 50%. Effective porosity refers to the proportion of the volume of connected pores actually participating in ion transport to the total volume, and its value is less than or equal to the total porosity of the negative electrode sheet, typically 60%-95% of the total porosity. In some embodiments of this application, the connectivity of the negative electrode sheet ranges from 0.3 to 0.95, preferably 0.5 to 0.9, and more preferably 0.6 to 0.8; the tortuosity ranges from 1.2 to 5.0, preferably 1.5 to 3.5, and more preferably 1.8 to 2.5. Thus, through the synergistic design of parameters such as effective porosity, connectivity, and tortuosity, the dynamic balance of the ion-electron-mechanical three-channel system can be maintained.

[0057] Through optimization of in-plane and out-of-plane conduction paths, the in-plane conductivity of the negative electrode sheet is optimized to range from 10 S / m to 10 S / m. 5 S / m, preferably 10 2 S / m~10 4 S / m, more preferably 5×10 2 S / m ~5×10 3S / m. The mechanical channel utilizes structural strategies such as circumferential constraint and crack blocking, with an elastic modulus ranging from 0.1 GPa to 50 GPa, preferably 1 GPa to 20 GPa, and more preferably 3 GPa to 15 GPa. Preferably, prestressed design and compaction window optimization can be employed to adapt to thick electrodes and high-load applications. Excessive outer layer thickness may increase ion transport paths; excessive density in the middle layer may induce local polarization; uneven stress distribution may lead to local failure. These adverse factors should be avoided in the design.

[0058] Furthermore, in this application, the negative electrode typically includes a negative current collector and a negative active layer located on at least one surface of the negative current collector, wherein the negative electrode material is located within the negative active layer. The phrase "a negative active layer located on at least one surface of the negative current collector" means that, in this application, the negative active layer can be disposed on one surface or two surfaces along the thickness direction of the negative current collector; this application does not impose any particular limitation on this. This application does not impose any particular limitation on the thickness of the negative active layer; specifically, it can be 20μm to 200μm, preferably 40μm to 120μm, and more preferably 50μm to 100μm. Typically, in addition to the negative electrode material, the negative active layer may also contain negative electrode binders, negative electrode conductive agents, etc., as needed. This application does not limit the type or content of the negative electrode binder or negative electrode conductive agent; any known materials can be used. Specifically, in some embodiments of this application, the mass ratio of the negative electrode material, the negative electrode conductive agent, and the negative electrode binder in the negative electrode active layer can be (85~96):(1~8):(2~10), preferably (90~94):(2~5):(3~7), and more preferably (91~93):(2~4):(4~6). Specifically, the negative electrode binder can include, but is not limited to, at least one of polyvinyl alcohol, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, or acrylated styrene-butadiene rubber. The negative electrode conductive agent can include, but is not limited to, at least one of acetylene black, Ketjen black, carbon nanotubes, carbon fibers, carbon dots, or graphene. In preparing the negative electrode sheet, quality control includes key control points such as particle size distribution, shell continuity, interlayer spacing spectrum, conductivity, residual solvent and moisture, and interfacial bonding strength. The moisture content is controlled below 50 ppm, preferably below 30 ppm, and more preferably below 20 ppm.

[0059] In some specific embodiments of this application, the material of the negative electrode current collector includes, but is not limited to, copper foil, aluminum foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a polymer substrate coated with a conductive metal, etc., and this application does not have any particular limitations. The conductive metal includes, but is not limited to, copper, nickel, or titanium, and the polymer substrate material includes, but is not limited to, at least one of polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate, polyethylene terephthalate, or poly(p-phenylene terephthalamide). In actual production processes, the negative electrode current collector is generally roughened, primed, or coupled to improve the interfacial bonding strength.

[0060] In addition to the negative electrode, a single battery cell also contains components such as a positive electrode, a separator, and an electrolyte. This application does not impose any special restrictions on other components. In order to make the technical solution of this application clearer and more complete, each component will be described in detail below.

[0061] Positive electrode sheet

[0062] The positive electrode includes a positive current collector and a positive active layer disposed on at least one surface of the positive current collector. Specifically, in this application, the positive active layer can be disposed on one surface or on two surfaces along the thickness direction of the positive current collector. Furthermore, in this application, the "surface of the positive current collector" can be the entire area of ​​the positive current collector or only a portion thereof; there are no particular limitations, as long as the purpose of this application is achieved.

[0063] The components in the positive electrode active layer generally include positive electrode active material, positive electrode conductive agent, and positive electrode binder. Typically, the content of the positive electrode active material is 85wt%~95wt%, the positive electrode conductive agent is 1wt%~8wt%, and the binder is 2wt%~8wt%. The positive electrode active material can be any material capable of reversibly intercalating and deintercalating Li. + Na + Substances containing alkali metal ions are used to ensure the normal charging and discharging of the electrochemical device. For example, positive electrode active materials include, but are not limited to, at least one of layered oxide positive electrode materials, spinel structure positive electrode materials, polyanion positive electrode materials, and lithium-rich manganese-based positive electrode materials. Layered oxide positive electrode materials include, but are not limited to, LiCoO2 and LiNi. 1-x-y Co x Mn y At least one of O2, LiNiCoAlO2, etc., and spinel structure cathode materials include, but are not limited to, LiMn2O4, LiNi 0.5 Mn 1.5At least one of O4, etc., and polyanionic cathode materials include, but are not limited to, at least one of LiFePO4, LiMnPO4, Li3V2(PO4)3, etc. Cathode conductive agents include, but are not limited to, at least one of acetylene black, Super-P carbon black, or amorphous carbon materials such as needle coke, or carbon nanotubes, or graphene, etc. Positive electrode binders include, but are not limited to, any one or at least two of the following: resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose; rubber-like polymers such as styrene-butadiene rubber (SBR), nitrile rubber (NBR), fluororubber, isoprene rubber, polybutadiene rubber, and ethylene-propylene rubber; thermoplastic elastomers such as styrene-butadiene-styrene block copolymers or their hydrides, ethylene-propylene-diene terpolymers (EPDM), styrene-ethylene-butadiene-ethylene copolymers, and styrene-isoprene-styrene block copolymers or their hydrides; soft resin-like polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymers, and propylene-α-olefin copolymers; fluorinated polymers such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene-ethylene copolymers; and polymer compositions with ion conductivity of alkali metal ions (especially lithium ions).

[0064] In the positive electrode sheet, there are no particular restrictions on the type of positive current collector; it can be any known material suitable for use as a positive current collector. Materials for the positive current collector include, but are not limited to, metals such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and materials such as carbon cloth and carbon paper. Furthermore, to reduce the electronic contact resistance between the positive current collector and the positive active material layer, conductive additives or conductive coatings can be applied to the surface of the positive current collector. Conductive additives include, but are not limited to, carbon and precious metals such as gold, platinum, and silver. The conductive coating can be a mixture of inorganic oxides, conductive agents, and positive electrode binders.

[0065] Separating membrane

[0066] To prevent short circuits, a separator is usually placed between the positive and negative electrodes.

[0067] There are no particular limitations on the material and shape of the separator, as long as it does not significantly impair the effectiveness of this application. The separator material can be resin, glass fiber, inorganic materials, etc., formed from materials stable to the electrolyte of this application. In some embodiments, the separator includes a porous sheet or non-woven fabric-like material with excellent liquid retention properties. Examples of resin or glass fiber separator materials include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, etc. In some embodiments, the polyolefin is polyethylene or polypropylene. In some embodiments, the polyolefin is polypropylene. The above-mentioned separator materials can be used alone or in any combination.

[0068] The separator can also be a material formed by laminating the above-mentioned materials, examples of which include, but are not limited to, a three-layer separator formed by laminating polypropylene, polyethylene, and polypropylene in that order.

[0069] Inorganic materials include, but are not limited to, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates (e.g., barium sulfate, calcium sulfate, etc.). The forms of inorganic materials include, but are not limited to, particulate or fibrous forms.

[0070] The separator can be in the form of a thin film, including but not limited to non-woven fabric, woven fabric, and microporous membranes. In the thin film form, the pore size of the separator is 0.01 μm to 1 μm, and the thickness is 5 μm to 50 μm. In addition to the above-mentioned independent thin film separators, the following separators can also be used: separators formed by using a resin-based adhesive to form a composite porous layer containing the above-mentioned inorganic particles on the surface of the positive electrode and / or negative electrode, for example, a separator formed by using fluororesin as an adhesive to form a porous layer of alumina particles with a particle size of less than 1 μm on both sides of the positive electrode.

[0071] The thickness of the separator is arbitrary. In some embodiments, the thickness of the separator is greater than 1 μm, greater than 5 μm, or greater than 8 μm. In some embodiments, the thickness of the separator is less than 50 μm, less than 40 μm, or less than 30 μm. When the thickness of the separator is within the above ranges, insulation and mechanical strength can be ensured, and the rate capability and energy density of the electrochemical device can be ensured.

[0072] In this application, the diaphragm may include a substrate and a surface treatment layer. The substrate may be a nonwoven fabric or composite membrane with a porous structure, and the material of the substrate may include at least one of polyethylene, polypropylene, polyethylene terephthalate, or polyimide. Optionally, a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane may be used. Optionally, a surface treatment layer is provided on at least one surface of the substrate. The surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing polymers and inorganic materials. For example, the inorganic layer includes inorganic particles and a binder. This application does not have any particular limitation on the aforementioned inorganic particles, and may include at least one of alumina, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. This application does not have any particular limitation on the aforementioned binders, and may include at least one of the aforementioned binders. The polymer layer contains a polymer, the polymer material of which includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, or poly(vinylidene fluoride-hexafluoropropylene).

[0073] electrolyte

[0074] Electrolytes serve to transport lithium ions and electrons, ensuring the formation of pathways within the electrochemical device. Electrolytes typically contain lithium salts, solvents, and additives. It should be noted that this application does not impose specific limitations on the amounts of each component in the electrolyte, as long as the purpose of this application is achieved.

[0075] Specifically, the battery cell of this application is suitable for one or more of the following systems: carbonates, ethers, nitriles, and ionic liquids (based on the solvent). It is compatible with film-forming additives such as fluoroethylene carbonate (FEC), LiNO3, borate esters, and vinylene carbonate (VC). These film-forming additives are used to form a more stable interface film and SEI film at the negative electrode interface, thereby improving the interface stability of the silicon-based negative electrode. In some embodiments of this application, FEC is preferred as the film-forming additive. Preferably, it can be used in conjunction with staged liquid injection, with the outer layer or ionic liquid serving as a functional unit for secondary injection. More preferably, it provides a blocking or acid-capturing strategy for positive electrode systems containing HF or high voltage.

[0076] The battery cells in this application embodiment can be packaged in various forms such as button cells, pouch cells, and hard-shell cells. The operating voltage range is between 1.7V and 2.8V, and the operating temperature range is between -20℃ and 60℃. The battery cells in this application embodiment can achieve large-capacity energy storage, meeting the needs of long-term energy storage, and achieving long-term energy storage of 4 hours or more. For example, they can be applied to energy storage scenarios such as 5 hours, 6 hours, and 8 hours. Long-term energy storage means being able to continuously discharge for 4 hours or even longer at rated power, or achieving large-scale, low-cost energy storage for several days or months.

[0077] The battery cell of this application has the following advantages:

[0078] a) A fundamental leap in interface engineering design concepts

[0079] Existing technologies primarily rely on passive protection strategies based on single-layer graphene oxide encapsulation, attempting to simultaneously address multiple functional requirements—chemical stability, electronic conduction, and mechanical buffering—with a single material. This leads to inherent contradictions and mutual constraints among these functional requirements. This application proposes an active synergistic control strategy with three layered structures. Through a design concept of functional separation and synergy, it achieves a fundamental leap from "passive encapsulation" to "active interface engineering." This layered design allows each layer to perform optimally under suitable conditions, avoiding compromises between multiple performance requirements inherent in single-layer structures and fundamentally breaking through the performance bottlenecks of traditional encapsulation technologies.

[0080] b) Systematic improvement in structural control accuracy

[0081] Existing technologies primarily regulate performance by controlling the reduction degree of graphene oxides. However, the methods for controlling structural parameters are singular and mutually coupled, making independent optimization of key properties difficult, resulting in significant batch-to-batch variations and poor performance predictability. This application establishes a dual-parameter programmable control system of "interlayer spacing-nanochannels," decoupling electronic conduction and ion / solvent selectivity into independently adjustable design parameters. This precise structural control capability enables quantitative design and engineering reproduction of material properties, significantly improving the controllability and reliability of the technology and laying the foundation for large-scale production.

[0082] c) Establishment of a multi-scale collaborative protection mechanism

[0083] Existing technologies lack a systematic approach to addressing the multiple failure mechanisms of silicon anodes, often introducing new problems while solving one, making it difficult to achieve overall performance optimization. This application constructs a triple synergistic protection mechanism of "chemical passivation - selective barrier - flexible buffer," providing specialized solutions for different failure modes of silicon anodes. The inner passivation layer addresses chemical instability by reducing nucleation overpotential and suppressing side reactions; the middle functional layer addresses transport and mechanical coupling issues through selective barrier and stress diffusion; and the outer buffer layer addresses interface adaptability issues through flexible buffering. This systematic protection strategy achieves comprehensive coverage of silicon anode failure mechanisms.

[0084] d) Modularization and cost optimization of functional components

[0085] Existing technologies have relatively fixed structures and compositions, making it difficult to adjust them according to different application needs and cost requirements, thus limiting their applicability and commercial feasibility. This application adopts a modular design concept, specifically designing the ionic liquid in the outer buffer layer as an optional component (0~15 wt%), which can be flexibly configured according to performance requirements and cost constraints. This design strategy not only reduces system complexity and cost but also provides a product series development path from basic to high-performance versions, enhancing the technology's market adaptability and commercial value.

[0086] e) Significant improvement in long-term stability and cycle durability

[0087] Existing single-layer packaging technologies are prone to progressive damage during repeated volume changes in silicon, including interlayer delamination, crack propagation, and conductive network degradation, resulting in limited long-term stability, particularly under high load and thick electrode conditions. This application effectively disperses stress concentration during cycling and slows down interface degradation through a gradient transition design and interlayer synergistic mechanism. The synergistic protection of the three-layer structure ensures that even if one layer suffers localized damage, the other layers can still maintain their protective function, significantly improving the system's fault tolerance and cycle durability.

[0088] f) Expansion of electrolyte compatibility and system integration capabilities

[0089] Existing technologies primarily optimize for specific electrolyte systems, limiting their versatility and making integration with other advanced battery technologies difficult, thus restricting their application scope. This application achieves broad compatibility with various electrolyte systems, including traditional carbonate systems, advanced ether systems, and emerging ionic liquid systems, through chemical passivation of the passivation layer and the design of selective barriers in the functional layer. Furthermore, this technology exhibits good synergy with advanced manufacturing processes such as staged electrolyte injection, providing more technological combination possibilities for constructing high-performance battery systems.

[0090] This application also provides a negative electrode sheet in a battery cell and a method for preparing the negative electrode material, as detailed below:

[0091] Preparation of anode materials: Anode materials are typically constructed layer-by-layer using methods such as spray drying, layer-by-layer self-assembly, or fluidized bed coating to achieve a three-layer structure. The inner passivation layer is prepared through atomic layer deposition or in-situ precursor conversion; the middle functional layer is constructed through GO deposition followed by low-temperature curing / reduction treatment; and the outer buffer layer is formed through solution casting, in-situ polymerization, or phase separation. A process flow diagram for preparing anode materials is shown below. Figure 1 As shown, the specific steps are as follows:

[0092] S100, Pre-treatment of silicon-based particles.

[0093] This step involves removing the natural oxide layer from the surface of the silicon-based particles and performing surface activation. Cleaning is performed using a dilute HF solution or argon plasma etching, while activation is achieved using a silane coupling agent or surface functionalization treatment.

[0094] S200, prepare the passivation layer.

[0095] This step involves depositing an inorganic passivation layer using atomic layer deposition (ALD) or precursor in-situ conversion processes.

[0096] When using the ALD process to prepare the passivation layer, the parameter range is a temperature of 150℃~300℃, preferably 200℃~250℃, and the number of cycles is determined according to the target thickness.

[0097] The precursor in-situ conversion process employs solution immersion followed by heat treatment, with a temperature range of 200℃~400℃, preferably 250℃~350℃, to avoid the upper limit of temperature-time for silicon-based particle damage.

[0098] S300, construct the functional layer.

[0099] This step typically involves impregnation or spray deposition of a GO dispersion, followed by low-heat-budget curing / reduction treatment. Low-heat-budget curing processes include at least one of laser treatment, flash evaporation, and hot plate treatment. Laser treatment uses a wavelength of 800nm~1200nm and a power density of 100W / cm². 2 ~1000W / cm 2The flash evaporation treatment intensity ranges from 1 ms to 100 ms; the hot plate treatment temperature ranges from 200℃ to 500℃, and the time ranges from 10 min to 120 min; the reduction treatment generally uses reducing gases or solutions and can be performed or omitted depending on actual needs. As mentioned in the application, excessive reduction may lead to interlayer collapse and hindered ion transport; therefore, excessive reduction of layered carbon in the functional layer must be avoided during the reduction process. All processes have upper energy limits set to prevent silicon-based particle necking or agglomeration. The preparation parameters can be adjusted according to actual needs.

[0100] S400, forming a buffer layer.

[0101] This step typically involves forming a flexible buffer layer through solution casting, in-situ polymerization, or phase separation. The polymer solution concentration is 5wt%~20wt%, and the coating is dried and cured at 50℃~150℃. Optionally, 0~15wt% ionic liquid can be introduced during the polymerization process for blending or in-situ compounding.

[0102] In this application, the technical implementation path of the anode material adopts a low-thermal-budget, multi-process family strategy, including optional process routes such as laser, flash evaporation, hot plate, and chemical reduction, combined with a staged / regional manufacturing strategy to achieve a mild and controllable construction of the interface structure. Through dual-parameter programmable control of interlayer spacing and nanochannels, the electron conduction and ion selectivity performance of the middle layer can be precisely adjusted, enabling quantitative design and engineering reproduction of performance.

[0103] Since the processing methods in each step are quite common, and the process parameters can be adjusted according to actual needs, this application will not elaborate on the specific operation process here. Those skilled in the art can make conventional adjustments according to actual needs.

[0104] Preparation of the negative electrode sheet: The negative electrode material is mixed with a conductive agent and a binder to form a slurry, using N-methylpyrrolidone (NMP) or water as a solvent. This slurry is then coated onto a roughened or pre-coated copper foil current collector. The drying temperature is 80℃~120℃, and the compaction process parameters are determined based on the load and thickness requirements.

[0105] It should be noted that the positive electrode sheet, separator, electrolyte, etc. can also be obtained by self-made or purchased. This application will not elaborate on the preparation methods of other components, all of which are obtained by purchase.

[0106] The quality control system during the preparation process includes key control points such as particle size distribution testing, shell continuity inspection, interlayer XRD characterization, conductivity measurement, residual solvent and moisture detection, and interfacial bonding strength testing. Precise control and online monitoring of process parameters ensure the stability and consistency of product quality.

[0107] Safety and environmental control during the preparation process: setting upper limits on energy and time for low thermal budget processing to avoid damage to the silicon substrate; upper limits on ionic liquid content to prevent swelling and degradation of adhesion properties; moisture content control to avoid side reactions; and safety measures such as humidity control of the operating environment and prevention of dust explosions.

[0108] Existing technologies mostly employ high-temperature heat treatment or high-power laser annealing, which have narrow process windows, high energy consumption, and are prone to damaging the silicon substrate. They also require sophisticated equipment and are expensive, limiting the industrial application of these technologies. This application utilizes a multi-process family of options, including laser, flash evaporation, hot plate, and chemical reduction, and employs a low thermal budget strategy to achieve gentle and controllable construction of the interface structure. This diverse range of process options not only improves the adaptability and equipment compatibility of the technology but also significantly reduces energy consumption and cost, avoids thermal damage to silicon particles, and provides a flexible solution for production at different scales and under different conditions.

[0109] After obtaining the components of a single battery cell, the separator, positive electrode, negative electrode, and electrolyte are assembled to form the battery cell. The assembly environment requires an oxygen content of <1 ppm and a moisture content of <1 ppm, and the operation is carried out in a glove box filled with argon gas. During assembly, it is necessary to ensure that the separator is positioned between the positive and negative electrode plates to prevent short circuits between them.

[0110] After the battery cells are fabricated, to ensure their normal and stable use, they typically undergo a three-stage treatment process: pretreatment, pre-lithiation, and formation. The formation stage employs a mild electrochemical protocol with a current rate range of 0.01C to 0.5C, preferably 0.05C to 0.2C, and more preferably 0.1C to 0.15C. A rate-temperature-pressure mapping strategy under thick electrode, high silicon content, and high surface pressure is optimized as a family of parameters.

[0111] In addition, this application also provides a battery device including the above-mentioned battery cell, wherein the battery device includes, but is not limited to, one or more of battery modules, battery packs, and energy storage batteries.

[0112] This application also provides an energy storage device, including the aforementioned battery device. The battery device in the energy storage device is used to store electrical energy. The energy storage device includes, but is not limited to, residential energy storage cabinets, commercial energy storage cabinets, energy storage containers, energy storage racks, energy storage power stations, energy storage battery packs, or portable energy storage systems. The energy storage device may also include an energy management system (EMS), a battery management system (BMS), and a power conversion system (PCS).

[0113] This application also provides an electrical device, including the aforementioned battery device. The battery device in the electrical device is used to provide electrical energy. The electrical device includes, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0114] The technical solution of this application will be described in detail below with reference to embodiments and comparative examples.

[0115] Test methods

[0116] Energy density test

[0117] The battery cells were charged and discharged using the Blue Electric testing system at a constant temperature of 25℃. The cells were charged at a constant current rate of 0.1C to the upper limit voltage of 4.2V, then charged at a constant voltage rate until the current dropped to 0.02C. After standing for 10 minutes, the cells were discharged at a constant current rate of 0.1C to the lower limit voltage of 2.75V. The discharge capacity and average discharge voltage were recorded. The battery mass was weighed using an electronic balance with an accuracy of 0.01g, and the mass energy density was calculated: Energy density (Wh / kg) = Discharge capacity (Ah) × Average discharge voltage (V) / Battery mass (kg). Three parallel samples were tested for each sample, and the average value was taken. Alternatively, equivalent testing methods conventional in this field can also be used for determination.

[0118] Interface stability test

[0119] A Li|| negative electrode half-cell was assembled, and electrochemical impedance spectroscopy (EIS) was performed at 25°C using an electrochemical workstation. Test parameters: frequency range 1MHz~0.01Hz, perturbation amplitude 5mV. Tests were conducted in the initial state and after the 10th, 50th, and 100th cycles (0.5C charge-discharge), and the charge transfer impedance (Rct) was recorded. n (where "n" represents the specific number of cycles). Interface stability is characterized by the impedance growth rate after 100 cycles: Growth rate (%) = (Rct) 100 - Rct0) / Rct0×100%. Alternatively, equivalent test methods conventional in this field can be used for determination.

[0120] Chemical stability test

[0121] The negative electrode material was placed in a standard electrolyte (1M LiPF6 dissolved in EC:DMC = 1:1, where "M" represents "mol / L", "1:1" is the volume ratio, EC is ethylene carbonate, and DMC is dimethyl carbonate) and sealed for 7 days at 45°C. The Si concentration in the immersion solution was determined by inductively coupled plasma optical emission spectrometry (ICP-OES), and the Si dissolution rate (%) was calculated based on the initial Si content in the negative electrode material. Alternatively, equivalent testing methods conventional in this field can be used for determination.

[0122] Ion conduction performance test

[0123] The negative electrode sheet was cut into 14mm diameter circular pieces and assembled into a symmetrical stainless steel structure. EIS testing was performed using an electrochemical workstation at 25℃, with a frequency range of 1MHz-0.1Hz and a perturbation amplitude of 10mV. The ion transport impedance (Rion) was determined based on the Nyquist plot, and the ionic conductivity was calculated as: σ = L / (Rion × S), where L is the electrode thickness and S is the test area. Alternatively, equivalent testing methods conventional in this field can be used for determination.

[0124] Mechanical cushioning performance test

[0125] The thickness of the negative electrode was monitored using an electrochemical in-situ dilatometer. The negative electrode was assembled into a half-cell, and the first charge-discharge cycle was performed at a 0.1C rate, with the electrode thickness change recorded in real time. The thickness expansion rate was calculated as follows: Expansion rate (%) = (Maximum thickness at 4.2V - Initial thickness) / Initial thickness × 100%. Alternatively, equivalent testing methods conventional in this field can be used for measurement.

[0126] Example 1

[0127] <Preparation of Anode Materials>

[0128] First, the silicon-based particles were surface-cleaned and activated. Then, an ALD process was used to form a passivation layer on the surface of the silicon-based particles. Following this, a GO dispersion was sprayed and deposited, and then a reduction treatment was performed to form a functional layer on the surface of the passivation layer. Next, a 5wt% polymer solution was poured onto the surface of the functional layer, and then dried and cured at 50°C to form a buffer layer on the surface of the functional layer. The specific parameters and performance of the anode material during and after preparation are shown in Table 1.

[0129] <Preparation of negative electrode sheet>

[0130] A negative electrode slurry was prepared by mixing negative electrode material, negative electrode conductive agent, and negative electrode binder in a mass ratio of 92:3:5. This slurry was then coated onto the upper and lower surfaces of a copper foil and subsequently cured to form the negative electrode active layer. The negative electrode conductive agent was carbon nanotubes, and the negative electrode binder was polyvinylidene fluoride.

[0131] <Preparation of battery cells>

[0132] The positive electrode, separator, and negative electrode are stacked in sequence and sealed with aluminum-plastic film. Before sealing, a vacuum is drawn to remove air, electrolyte is injected, and then heat-sealed. After the battery cell assembly is complete, it is left to stand for 24 hours to allow the electrolyte to fully wet the electrode and separator. The positive electrode uses NCM811 ternary cathode material with an areal density of 15 mg / cm³. 2 The negative electrode uses silicon-based particles with a composite layer on the surface. The parameters of the silicon-based particles and the composite layer are shown in Table 1. The electrolyte is a 1M LiPF6 electrolyte system, and the electrolyte system contains 5wt% film-forming additive FEC. The solvent in the electrolyte system is a mixed solvent of EC:DMC:EMC=1:1:1 (volume ratio, EMC is methyl ethyl carbonate).

[0133] Examples 2 to 7

[0134] Compared to Example 1, the main difference lies in changing the type of silicon-based particles, equivalent particle size, and other parameters, as shown in Table 1.

[0135] Examples 8 to 18

[0136] Compared to Example 1, the main difference lies in changing parameters such as the composition, thickness, and coverage of the passivation layer, as shown in Table 1.

[0137] Examples 19 to 34

[0138] Compared to Example 1, the main difference lies in changing parameters such as the type of layered carbon, interlayer spacing, and orientation degree of oriented nanochannels in the functional layer, as shown in Table 1.

[0139] Examples 35-46

[0140] Compared to Example 1, the main difference lies in changing the type, concentration, and elastic modulus of the polymer in the polymer solution, as shown in Table 1.

[0141] Example 47

[0142] Compared to Example 1, the main difference lies in the method used to prepare the negative electrode material:

[0143] <Preparation of Anode Materials>

[0144] First, the silicon-based particles are surface-cleaned and activated. Then, an ALD process is used to form a passivation layer on the surface of the silicon-based particles. After that, a GO dispersion is sprayed and deposited, followed by a reduction treatment to form a functional layer on the surface of the passivation layer. Then, a 5wt% polymer solution and an ionic liquid are poured onto the surface of the functional layer, and then dried and cured at 50°C to form a buffer layer on the surface of the functional layer. In the cured buffer layer, the mass content of the ionic liquid is 5% based on the mass of the buffer layer.

[0145] Examples 48-49

[0146] Compared to Example 47, the main difference lies in the content of the ionic liquid, as shown in Table 1.

[0147] Example 50

[0148] Compared to Example 1, the main difference is that polyvinylidene fluoride-hexafluoropropylene copolymer is used instead of polyacrylic acid.

[0149] Comparative Example 1

[0150] Compared to Example 1, the main difference is that silicon-based particles are directly used as the negative electrode material to prepare the negative electrode sheet and battery cell.

[0151] Comparative Example 2

[0152] Compared to Example 1, the main difference lies in the method used to prepare the negative electrode material:

[0153] <Preparation of Anode Materials>

[0154] First, the silicon-based particles were surface-cleaned and activated, then coated with GO dispersion, followed by reduction treatment to form a functional layer on the surface of the silicon-based particles. Next, a 5wt% polymer solution was poured onto the surface of the functional layer, and then dried and cured at 50°C to form a buffer layer on the surface of the functional layer. The specific parameters and performance of the anode material during and after preparation are shown in Table 1.

[0155] Comparative Example 3

[0156] Compared to Example 1, the main difference lies in the method used to prepare the negative electrode material:

[0157] <Preparation of Anode Materials>

[0158] First, the silicon-based particles were surface-cleaned and activated. Then, an ALD process was used to form a passivation layer on the surface of the silicon-based particles. Following this, a GO dispersion was sprayed and deposited, and then a reduction treatment was performed to form a functional layer on the surface of the passivation layer. The specific parameters and performance of the anode material during and after preparation are shown in Table 1.

[0159] Comparative Example 4

[0160] Compared to Example 1, the main difference lies in the method used to prepare the negative electrode material:

[0161] <Preparation of Anode Materials>

[0162] First, the silicon-based particles were surface-cleaned and activated. Then, an ALD process was used to form a passivation layer on the surface of the silicon-based particles. Next, a 5wt% polymer solution was poured onto the surface of the passivation layer, and then dried and cured at 50°C to form a buffer layer on the surface of the passivation layer. The specific parameters and performance of the negative electrode material during and after preparation are shown in Table 1.

[0163] Comparative Examples 5 to 6

[0164] Compared to Example 1, the main difference lies in the different interlayer spacing between the layered carbons in the functional layer, as shown in Table 1.

[0165] Comparative Examples 7 to 8

[0166] Compared to Example 1, the main difference lies in the different orientation of the oriented nanochannels in the functional layer, as shown in Table 1.

[0167] The performance of the individual cells in the examples and comparative examples was tested respectively, and the test results are shown in Table 2.

[0168] Table 1

[0169]

[0170] Table 2

[0171]

[0172] As can be seen from the above, the battery cell of this application embodiment has good comprehensive performance. It not only has high energy density, but also excellent chemical stability, ion conduction performance and mechanical buffering performance. As a result, the battery cell of this application embodiment has high interface stability and is not easy to fail.

[0173] Specifically, as shown in Example 1 and Comparative Example 1, since the composite layer design in the negative electrode material of this application mainly focuses on optimizing interface stability and has little impact on the lithium storage capacity of the silicon-based particles themselves, the energy densities of Example 1 and Comparative Example 1 are at similar levels, and even most of the comparative examples and examples have energy densities that are quite close, mostly within the range of 240Wh / kg to 255Wh / kg. The difference between the comparative examples and the examples mainly lies in the interface-related performance. Compared with battery cells that directly use silicon-based particles as negative electrode materials, the battery cells of the embodiments of this application can not only maintain a high energy density, but also have extremely high interface stability after being modified by the composite layer formed by the three layer structures of passivation layer, functional layer and buffer layer, ensuring that the battery cells containing silicon-based particles can be practically applied. In particular, Examples 2 and 3 achieved higher energy densities (>265 Wh / kg) by optimizing the particle size of silicon-based particles (100nm~200nm).

[0174] Comparative Examples 1 to 8, lacking a complete three-layer composite structure, all exhibited interface impedance growth rates exceeding 150% and Si dissolution rates exceeding 1.5%, demonstrating significant interface failure characteristics. In contrast, the examples, through the synergistic effect of the three-layer composite structure, controlled the interface impedance growth rate to below 70% and the Si dissolution rate to below 0.65%. In particular, Examples 8, 9, 13, 14, 31, and 32, by optimizing the passivation layer parameters (coverage 90%–95%, thickness 1 nm–5 nm), achieved further improvements in interface and chemical stability.

[0175] As shown in Examples 1, 20-28, and Comparative Examples 5-6, the interlayer spacing between the layered carbons in the functional layer needs to be maintained within the range of 0.4 nm to 2.5 nm. Too small an interlayer spacing can easily lead to reduced ion conductivity, thus affecting the interface stability of the battery cell; too large an interlayer spacing makes it difficult to construct a conductive network, also resulting in reduced ion conductivity and affecting the interface stability of the battery cell. Due to the lack of effective ion conduction channel design, the ion conductivity of the comparative examples was all below 1.5 × 10⁻⁶. -4 S / cm. In particular, the interlayer spacing is preferably 0.5nm~2.0nm, more preferably 0.7nm~1.5nm, which can ensure that the functional layer has better ion conduction performance and further improve the interface stability of the battery cell.

[0176] As shown in Examples 1, 29-34, and Comparative Examples 7-8, the orientation degree of the oriented nanochannels of layered carbon in the functional layer needs to be in the range of 0.3-0.9. Too small or too large an orientation degree will prevent the functional layer from constructing a selective barrier, thus affecting the interfacial stability of the battery cell. Specifically, an orientation degree of 0.5-0.8, more preferably 0.6-0.7, ensures that the functional layer has superior selectivity, further improving the interfacial stability of the battery cell.

[0177] Furthermore, Examples 40-42, by further optimizing the elastic modulus of the polymer in the buffer layer, ensured that the thickness expansion rate was controlled within 18%, further improving the buffering effect of the buffer layer. In contrast, the comparative examples, lacking the stress buffering effect of the buffer layer, all had thickness expansion rates exceeding 50%.

[0178] In summary, this application, through the synergistic design of a three-layer composite structure consisting of a passivation layer, a functional layer, and a buffer layer, significantly improves the interface stability, chemical stability, ion conduction performance, and mechanical buffering performance of silicon-based anodes while maintaining the high energy density advantage of silicon-based anodes, effectively addressing the technical problem of interface failure in silicon-based anodes.

[0179] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes can be made in form and detail without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A battery cell, characterized in that, Includes a negative electrode sheet, wherein the negative electrode sheet includes a negative electrode material, wherein the negative electrode material includes silicon-based particles, and the surface of the silicon-based particles is coated with a composite layer; The composite layer comprises a passivation layer, a functional layer, and a buffer layer sequentially disposed therefrom. The passivation layer comprises LiF, Li3PO4, and SiO2. x Li z AlO y At least one of Al2O3, where x ranges from 0.5 to 2, z+3=2y, z ranges from 0.5 to 5.0, and y ranges from 1.5 to 4.0; The functional layer comprises layered carbon, which includes at least one of graphene oxide, reduced graphene oxide, or nitrogen-doped graphene oxide, and the interlayer spacing between adjacent layered carbons is 0.4 nm to 2.5 nm, and the orientation degree of the oriented nanochannels of the layered carbon is 0.3 to 0.

9. The buffer layer comprises an elastic polymer with an elastic modulus of 0.1 GPa to 10 GPa and a thickness of 2 nm to 50 nm.

2. The battery cell according to claim 1, characterized in that, The equivalent particle size of the silicon-based particles is 50nm~1000nm.

3. The battery cell according to claim 1, characterized in that, The thickness of the passivation layer is 0.5 nm to 10 nm.

4. The battery cell according to claim 1, characterized in that, On the surface of the silicon-based particles, the passivation layer has a coverage of 80% to 99%.

5. The battery cell according to claim 1, characterized in that, The elastic polymer includes at least one of polyvinylidene fluoride-hexafluoropropylene copolymer or polyacrylic acid.

6. The battery cell according to claim 1, characterized in that, The buffer layer also contains an additive liquid, and the mass content of the additive liquid is 0-15% based on the mass of the buffer layer; the additive liquid includes difluorosulfonamide anions.

7. The battery cell according to claim 1, characterized in that, The total porosity of the negative electrode sheet is 30%~70%.

8. The battery cell according to any one of claims 1 to 7, characterized in that, It also includes a positive electrode, a separator, and an electrolyte. The positive electrode, the separator, and the negative electrode are stacked in sequence to form a battery cell assembly, and the battery cell assembly is immersed in the electrolyte.

9. A method for preparing a battery cell according to any one of claims 1 to 8, characterized in that, The battery cell includes a negative electrode sheet, and the negative electrode sheet includes a negative electrode material. The preparation of the negative electrode material includes the following steps: A passivation layer is formed on the surface of silicon-based particles using atomic layer deposition or precursor in-situ conversion processes. The passivation layer includes LiF, Li3PO4, and SiO2. x Li z AlO y At least one of Al2O3, where x ranges from 0.5 to 2, z+3=2y, z ranges from 0.5 to 5.0, and y ranges from 1.5 to 4.0; A dispersion is placed on the surface of the passivation layer and then cured to form a functional layer. The dispersion includes layered carbon, which includes at least one of graphene oxide or nitrogen-doped graphene oxide. The curing temperature is lower than the phase transition temperature of the silicon-based particles. A polymer solution is coated onto the surface of the functional layer and then dried and cured at 50°C to 150°C to form a buffer layer. The polymer solution includes an elastic polymer.

10. The method for preparing a battery cell according to claim 9, characterized in that, The concentration of the polymer solution is 5wt% to 20wt%.

11. The method for preparing a battery cell according to claim 9, characterized in that, After the functional layer is solidified, a reduction process is performed.

12. A battery device, characterized in that, The battery device includes a battery cell as described in any one of claims 1 to 8, or a battery cell prepared by the method of preparing a battery cell as described in any one of claims 9 to 11, and the battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

13. An energy storage device, characterized in that, Includes the battery device of claim 12, the battery device being used for storing electrical energy.

14. An electrical appliance, characterized in that, Includes the battery device of claim 12, the battery device being used to provide electrical energy.

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