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

Abstract

The application relates to the field of electrochemical 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. The battery monomer comprises a battery core assembly, the battery core assembly is stacked by a positive electrode, a diaphragm and a negative electrode or is wound; a shell, the battery core assembly is located in the shell; and an electrolyte, the electrolyte is located in the shell, and the electrolyte comprises a supramolecular cage compound; the supramolecular cage compound has a skeleton, and the skeleton surrounds to form a cavity. The battery monomer can at least well inhibit gas from forming bubbles, thereby effectively reducing the phenomenon that the battery monomer is deformed due to swelling, and can improve the safety performance and use performance of the battery monomer.

Description

Technical Field

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

[0002] During operation, various side reactions inevitably occur between the electrolyte and electrode materials in battery cells such as lithium-ion batteries. Among these, gas generation is one of the most common and difficult-to-eliminate phenomena. These gases gradually accumulate in the electrolyte and, after reaching a supersaturated state, nucleate and form bubbles at the electrode interface or within the electrolyte mass. These bubbles cause significant swelling and deformation of the battery cell, leading to a series of chain reactions, including reduced contact area between the electrode and electrolyte and increased local current density, severely impacting the safety and performance of the battery cell. Summary of the Invention

[0003] This application provides a battery cell and its preparation method, battery device, energy storage device, and power consumption device. The battery cell in this application can at least effectively suppress the formation of gas bubbles, thereby effectively reducing the phenomenon of bulging and deformation of the battery cell and improving the safety and performance of the battery cell.

[0004] The first aspect of this application provides a battery cell, comprising: a cell assembly, the cell assembly being formed by stacking or winding a positive electrode, a separator, and a negative electrode; a housing, the cell assembly being located inside the housing; and an electrolyte, the electrolyte being located inside the housing, and the electrolyte comprising a supramolecular cage compound having a framework, the framework surrounding to form a cavity.

[0005] The second aspect of this application also provides a method for preparing a battery cell, comprising the following steps: sequentially stacking or winding a positive electrode, a separator, and a negative electrode to form a cell assembly; placing the cell assembly within a housing, wherein an electrolyte is disposed within the housing, and the electrolyte includes a supramolecular cage compound; wherein the method for preparing the supramolecular cage compound comprises the following steps: dissolving a multifunctional organic monomer in an organic solvent, and then performing a condensation reaction to form a supramolecular cage compound, wherein the number of functional groups used for the reaction in the multifunctional organic monomer is not less than 3; or dissolving a metal salt and a multidentate organic ligand in an organic solvent, and then self-assembling to form a supramolecular cage compound.

[0006] A third aspect of this application provides a battery device, including a battery cell as described in the first aspect, or a battery cell prepared by a manufacturing method as described in the second aspect.

[0007] A fourth aspect of this application provides an energy storage device, including a battery device as described in the third aspect, the battery device being used to store electrical energy.

[0008] The fifth aspect of this application provides an electrical device, including a battery device as described in the third aspect, the battery device being used to provide electrical energy.

[0009] The technical solution provided in this application has at least the following advantages: In the battery cell of this application, the cavity structure of the supramolecular cage compound can act as a "molecular trap" for gas molecules. When gas molecules such as carbon monoxide, carbon dioxide, and ethylene are generated during operation or storage of the battery cell, these gases, in their dissolved state, can enter the cavity of the supramolecular cage through the framework. After entering the cavity, the inner wall of the framework will generate non-covalent interactions such as van der Waals forces and dipole interactions with the gas molecules, making the gas molecules stably bound inside the cavity. Therefore, gas molecules in the dissolved state can be captured and fixed by the cavity of the supramolecular cage, thereby significantly reducing the concentration of free gas in the electrolyte, delaying or even preventing the gas from reaching a supersaturated state, and thus inhibiting the nucleation and growth of bubbles. Because the cavity structure in the supramolecular cage compound can specifically capture and store free gas, the battery cell of this application is not prone to bulging and deformation due to gas accumulation, thereby improving the safety and performance of the battery cell. Attached Figure Description

[0010] 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.

[0011] Figure 1 This is a process flow diagram of the battery cell manufacturing process in the embodiments of this application; Figure 2 This is a schematic diagram of the overall structure of the battery device in the embodiments of this application; Figure 3 This is a schematic diagram of the disassembled battery device in an embodiment of this application.

[0012] Reference numerals: 10-box; 11-first part; 12-second part; 20-cell battery; 100-battery assembly. Detailed Implementation

[0013] As the background technology shows, battery cells inevitably undergo side reactions that generate gases. When these gases gradually accumulate and reach a supersaturated state, they cause the battery cells to swell and deform, leading to a series of chain reactions such as reduced contact area between the electrodes and the electrolyte, and increased local current density. These issues severely negatively impact the safety and performance of the battery cells. For example, the reductive decomposition of electrolytes containing carbonate solvents at low potentials at the negative electrode produces gases such as ethylene and carbon monoxide, while the oxidative decomposition at high potentials at the positive electrode and the reaction with lattice oxygen released from the positive electrode material produce gases such as carbon dioxide. The accumulation of these gases, reaching a supersaturated state, will all severely negatively affect the safety and performance of the battery cells. Moreover, energy storage batteries typically employ large-capacity pouch or square aluminum shell structures, making them significantly more sensitive to internal gas accumulation than smaller batteries. Gas generation is particularly prominent during high-temperature storage or long-term cycling.

[0014] To address the gas generation problem in individual battery cells, existing technologies mainly focus on the following aspects.

[0015] 1. At the level of electrolyte additives, film-forming additives are the most widely used technical approach. Additives such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC) added to the electrolyte can preferentially undergo reductive decomposition on the negative electrode surface before solvent molecules, forming a dense SEI (Solid Electrolyte Interphase) film rich in inorganic components, thereby inhibiting subsequent solvent decomposition reactions to a certain extent. Similarly, adding additives such as vinyl sulfate to the electrolyte can construct a protective CEI (Cathode Electrolyte Interface) film on the positive electrode surface, inhibiting the oxidative decomposition of the electrolyte. The mechanism of action of these additives is essentially to slow down the occurrence rate of side reactions through interface passivation.

[0016] 2. At the electrolyte bulk optimization level, current methods to improve the overall stability of the electrolyte include adjusting solvent composition, optimizing lithium salt type and concentration, and introducing functional co-solvents. For example, using a high-concentration electrolyte can reduce the number of free solvent molecules, thereby reducing the probability of solvent decomposition; introducing fluorinated solvents can improve the oxidative stability of the electrolyte. The purpose of these methods is also to reduce the occurrence of side reactions.

[0017] 3. At the electrode material level, the release of lattice oxygen and side reactions with the electrolyte can be suppressed by means of surface coating and element doping of positive electrode active materials; the irreversible capacity and associated gas generation in the first cycle can be reduced by means of pre-lithiation and surface modification of negative electrode active materials.

[0018] 4. At the battery design level, some solutions adopt passive measures such as reserving gas space, setting up exhaust valves, and strengthening the casing to contain or release the generated gas.

[0019] Although existing technologies have addressed the gas generation problem in lithium-ion batteries from multiple perspectives, the following key defects and limitations still exist.

[0020] 1. The fundamental limitation of existing film-forming additives lies in the fact that they act on the electrode interface rather than the gas itself. Regardless of the density of the SEI or CEI film, they cannot completely prevent side reactions; they can only reduce the reaction rate to a certain extent. Under high-temperature storage or long-term cycling conditions, gas will continue to be generated and accumulate. More importantly, these additives have no effect on gas molecules that have already been generated and dissolved in the electrolyte, and cannot prevent nucleation and bubble growth processes after supersaturation.

[0021] 2. Electrolyte bulk optimization strategies face a dilemma of balancing multiple performance aspects. While high-concentration electrolytes can reduce solvent decomposition, they significantly increase electrolyte viscosity, reduce ionic conductivity, and raise costs. The introduction of fluorinated solvents may lead to decreased low-temperature performance and poor compatibility with existing processes. These methods often sacrifice other performance aspects while suppressing gas generation. Moreover, similar to film-forming additives, this approach can only reduce the reaction rate to a certain extent; under high-temperature storage or long-term cycling conditions, gas will continue to be generated and accumulate.

[0022] 3. The limitation of the modification methods for positive and negative electrode active materials lies in the fact that their effect is limited to the material itself and cannot cope with the gases generated by electrolyte decomposition. At the same time, the additional material processing steps increase manufacturing costs and process complexity, making it difficult to promote on a large scale in the cost-sensitive energy storage field.

[0023] 4. Passive gas containment or release solutions not only fail to solve the fundamental problem of gas production, but may also introduce additional safety hazards. Reserving space for gas reduces the battery's volumetric energy density; vent valve designs increase the risk of electrolyte leakage and external contaminant intrusion.

[0024] In summary, existing technologies lack an active intervention mechanism that can directly act on gas molecules and capture and fix them before nucleation. This functional deficiency prevents a fundamental solution to the gas generation problem in individual battery cells. When gas gradually accumulates in the electrolyte and reaches a supersaturated state, it nucleates and forms bubbles at the electrode interface or in the electrolyte mass, leading to a series of chain reactions such as swelling and deformation of the pouch battery, reduced contact area between the electrode and electrolyte, and increased local current density. In severe cases, this can trigger safety accidents such as thermal runaway. Especially under harsh conditions such as high-temperature storage (typically 45℃~60℃), the swelling and safety risks caused by gas accumulation remain prominent challenges for individual battery cells in energy storage and power consumption devices.

[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 embodiments of this application, the electrolyte of the battery cell contains a supramolecular cage compound, which can selectively capture side reaction gas molecules, thereby significantly reducing the concentration of free gas in the electrolyte, delaying or even preventing the gas from reaching a supersaturated state, and thus inhibiting the nucleation and growth process of bubbles. In this way, the battery cell is less prone to bulging and deformation, which can improve the safety and performance of the battery cell.

[0026] 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).

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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%.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] This application provides a battery cell, including a cell assembly, a casing, and an electrolyte; the electrolyte and the cell assembly are located within the casing. The electrolyte includes a supramolecular cage compound, which has a framework that surrounds and forms a cavity.

[0037] It should be noted that the term "supramolecular cage compound" in this application refers to a discrete cage-like molecule with a defined cavity structure formed through self-assembly via covalent or coordinate bonds. Supramolecular cage compounds have definite molecular weights and structures and are soluble in organic solvents. Structurally, supramolecular cage compounds have a closed framework, which encloses the cavity. Furthermore, supramolecular cage compounds differ from MOF (Metal-Organic Framework) and COF (Covalent Organic Framework) materials. While MOF and COF materials also contain porous structures, they are infinitely extended periodic framework materials, belonging to polymers, not discrete molecules, and are generally insoluble in electrolytes. Therefore, MOF and COF materials are not within the scope of supramolecular cage compounds in this application. Additionally, supramolecular cage compounds often have a near-spherical shape; therefore, in this application, "cavity size" refers to the equivalent diameter of the supramolecular cage compound.

[0038] In this embodiment, the cavity structure of the supramolecular cage compound can act as a "molecular trap" for gas molecules. When gas molecules such as carbon monoxide, carbon dioxide, and ethylene are generated by the battery cell during operation or storage, these gases, in their dissolved state, can enter the cavity of the supramolecular cage through the framework. After entering the cavity, the inner wall of the framework generates non-covalent interactions such as van der Waals forces and dipole interactions with the gas molecules, causing the gas molecules to be stably bound inside the cavity. Therefore, gas molecules in their dissolved state can be captured and fixed by the cavity of the supramolecular cage, thereby significantly reducing the concentration of free gas in the electrolyte, delaying or even preventing the gas from reaching a supersaturated state, and thus inhibiting the nucleation and growth of bubbles. Because the cavity structure in the supramolecular cage compound can specifically capture and store free gas, the battery cell in this embodiment is less prone to bulging and deformation due to gas accumulation, thereby improving the safety and performance of the battery cell.

[0039] The cavity size of the supramolecular cage is a core parameter determining its gas capture selectivity and efficiency. The cavity size needs to be designed to match the dynamic diameter of the target gas molecules, allowing them to enter the cavity and be stably captured through host-guest interactions. When side reactions occur in a battery cell, the sizes of the generated gas molecules are generally as follows: carbon dioxide approximately 0.33 nm, ethylene approximately 0.42 nm, and carbon monoxide approximately 0.38 nm. Therefore, in some embodiments of this application, to ensure that the cavity can accommodate the aforementioned target gas molecules and provide sufficient interaction space, the cavity size is generally 0.3 nm to 1.0 nm, specifically 0.3 nm, 0.35 nm, 0.4 nm, 0.42 nm, 0.45 nm, 0.5 nm, 0.55 nm, 0.58 nm, 0.6 nm, 0.8 nm, 1.0 nm, or within any range of two of the above values. If the cavity size is too small, gas molecules will be unable to enter; if the cavity size is too large, the interaction strength between the supramolecular cage compound and the gas molecules will be reduced, affecting the capture efficiency. Optionally, in some embodiments of this application, the cavity size is 0.4 nm to 0.6 nm. This size range is well matched with the kinetic diameters of carbon dioxide and ethylene (the two main types of gases produced by the side reaction), enabling efficient capture of these two main side reaction gases. Further, the cavity size is 0.45 nm to 0.55 nm. This size range provides optimal size matching for carbon dioxide and ethylene, resulting in higher capture selectivity and efficiency. It should also be noted that in actual production, the cavity size of the prepared supramolecular cage compound may have errors. Therefore, supramolecular cage compounds with cavity sizes outside the 0.4 nm to 0.6 nm or 0.45 nm to 0.55 nm range are permissible in the electrolyte, as long as most sizes meet the requirements and can effectively adsorb gases generated during the cycle life, preventing significant bulging of the battery cells.

[0040] This application does not have any particular requirements regarding the type of supramolecular cage compound, as long as it meets the purpose of this application. As an example, in some embodiments of this application, the supramolecular cage compound includes at least one of organic supramolecular cage compounds or organometallic supramolecular cage compounds. Specifically, the framework structure of organic supramolecular cage compounds is constructed from organic matter based on covalent bonds, while the framework of organometallic supramolecular cage compounds is formed by metal nodes and organic ligands connected by coordination bonds. Compared to organometallic supramolecular cage compounds, organic supramolecular cage compounds have advantages such as mature synthetic routes, strong structural tunability, and no introduction of metal ions to interfere with electrochemical reactions.

[0041] In some embodiments of this application, the skeleton of the organic supramolecular cage compound can be formed through dynamic covalent reactions. For example, Schiff base-type organic cages can be formed by imine bonds, and borate ester-type organic cages can be formed by borate ester bonds. In other embodiments, the organic supramolecular cage compound can also be formed through condensation reactions, for example, amide-type organic cages can be formed by amide bonds. Therefore, specifically, in the embodiments of this application, the skeleton of the organic supramolecular cage compound includes, but is not limited to, at least one of Schiff base-type organic cages, borate ester-type organic cages, and amide-type organic cages. Among them, Schiff base-type organic cages have mild synthesis conditions, high yields, and a wide range of adjustable cavity sizes, therefore, organic supramolecular cage compounds with Schiff base-type organic cage skeletons are widely used.

[0042] In some embodiments of this application, the metal element in the metal node of the metal-organic supramolecular cage compound is usually selected as a metal element with relatively high stability in the chemical environment of the battery cell, specifically including at least one of zinc, copper or palladium.

[0043] The distribution of supramolecular cage compounds in the electrolyte directly affects their gas capture capability. To ensure that the supramolecular cage compounds are more uniformly dispersed in the electrolyte, allowing each molecule to function as an independent gas capture unit and maximizing capture efficiency, in some embodiments of this application, modifying groups are grafted onto the outer wall of the supramolecular cage compound's framework. This ensures that the supramolecular cage compound dissolves better and is uniformly dispersed in the electrolyte. Modifying groups include, but are not limited to, at least one of C1-C6 fluoroalkyl, C1-C6 fluoroalkoxy, C1-C6 alkoxy, or C2-C6 acyloxy groups; for example, modifying groups include, but are not limited to, at least one of trifluoromethyl, 2,2,2-trifluoroethoxy, methoxy, ethoxy, acetoxy, or propionyloxy groups. The introduction of fluoroalkyl groups can improve the compatibility of the supramolecular cage compound with fluorinated solvents and carbonates; the introduction of polar groups such as acyloxy and alkoxy groups can enhance the interaction between the supramolecular cage compound and the carbonate solvent.

[0044] Of course, in some other embodiments of this application, it is also possible not to graft modifying groups on the outside of the skeleton. In this case, the supramolecular cage compound can maintain a stable nanoscale dispersion in the electrolyte. However, this requires ensuring that the nanoscale dispersion remains stable throughout the battery cell's lifespan, without significant sedimentation or aggregation. The nanoscale dispersed supramolecular cage compound can still capture gas molecules through the exposed cavity openings on its surface, but the capture efficiency may be lower than that of the completely dissolved state.

[0045] Since the binding between gas molecules and the molecules in the cavity is reversible after the gas molecules enter, a dynamic binding-dissociation equilibrium exists between the supramolecular cage and the gas molecules; when the binding force is insufficient, gas molecules will also escape from the cavity. Therefore, in some embodiments of this application, trapping groups can be provided on the inner wall of the supramolecular cage compound framework to enhance the interaction force between gas molecules and the inner wall of the framework, ensuring that gas molecules are less likely to escape. The trapping groups include, but are not limited to, at least one of nitrogen-containing groups or aromatic groups; for example, nitrogen-containing groups include, but are not limited to, at least one of pyridyl, pyrazinyl, and triazineyl, and aromatic groups include naphthyl, etc. Introducing nitrogen-containing groups such as pyridyl, pyrazinyl, and triazineyl can enhance the affinity for carbon dioxide through Lewis acid-base interactions; introducing aromatic groups such as naphthyl can enhance the trapping ability for unsaturated hydrocarbon gases through π-π interactions.

[0046] If the amount of supramolecular cage compound added is too low, the capture capacity will be insufficient, and gas accumulation cannot be effectively suppressed; if the amount of supramolecular cage compound added is too high, it may affect the key properties of the electrolyte such as ionic conductivity and viscosity, while increasing costs. Considering the overall performance and production cost of the battery cell, in some embodiments of this application, the mass content of the supramolecular cage compound is 0.01% to 10% based on the mass of the electrolyte, optionally 0.1% to 5%; for example, 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 1%, 2%, 3%, 5%, 8%, 10%, etc., or within the range of any two of the above values. This range covers various application scenarios from trace addition to high concentration addition, providing flexible formulation design space for battery cells with different gas generation levels. Optionally, in some embodiments of this application, the mass content of the supramolecular cage compound is 0.1% to 5% based on the mass of the electrolyte. Within this range, the supramolecular cage compound can provide sufficient gas capture capacity while having little impact on the ion transport performance of the electrolyte. Further optionally, in some embodiments of this application, the mass content of the supramolecular cage compound is 0.5% to 2% based on the mass of the electrolyte. This range is the optimal range for balancing gas capture effect and overall performance, and can achieve a significant gas generation suppression effect without substantially affecting the bulk performance of the electrolyte.

[0047] In this embodiment, the supramolecular cage compound is used to capture gases generated by side reactions, thus enabling its use in conjunction with other functional additives such as film-forming additives in the electrolyte. Film-forming additives can slow down the rate of side reactions (reducing gas generation) by constructing a dense interfacial film, while the supramolecular cage compound can reduce the effective concentration of already generated gases (preventing gas accumulation). When the supramolecular cage compound is used synergistically with the film-forming additive in the same electrolyte, it can both reduce the generation of reactive gases and effectively inhibit gas accumulation and bubble formation. In fact, in practical use, the electrolyte contains not only the supramolecular cage compound but also organic solvents, lithium salts, and other optional functional additives. This application does not have specific requirements regarding the specific types and amounts of each component, as long as they meet the purpose of this application; examples are provided below.

[0048] In some embodiments of this application, the lithium salt may include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide [LiN(SO2F)2], lithium bis(trifluoromethanesulfonyl)imide [LiNH(SO2CF3)2], lithium trifluoromethanesulfonate (LiCF3SO3), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorodioxalate phosphate (LiODFP), and lithium tetrafluorooxalate phosphate (LiOTFP). This application does not impose any particular limitation on the content of the electrolyte salt in the electrolyte, as long as the purpose of this application is achieved. For example, based on the mass of the electrolyte, the mass percentage content of the lithium salt is 8% to 15%.

[0049] This application does not impose any particular limitation on organic solvents, as long as they achieve the purpose of this application. For example, organic solvents may include, but are not limited to, at least one of carbonate compounds, carboxylic acid ester compounds, ether compounds, or other organic solvents. The aforementioned carbonate compounds may include, but are not limited to, at least one of chain carbonate compounds, cyclic carbonate compounds, or fluorocarbonate compounds. The aforementioned chain carbonate compounds may include, but are not limited to, at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), or methyl ethyl carbonate (EMC). The aforementioned cyclic carbonates may include, but are not limited to, at least one of ethylene carbonate (EC), butylene carbonate (BC), or vinyl ethylene carbonate (VEC). Fluorocarbonate compounds may include, but are not limited to, at least one of fluoroethylene carbonate, fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, or trifluoromethylethylene carbonate. The aforementioned carboxylic acid ester compounds may include, but are not limited to, at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanolactone, valproic acid lactone, or caprolactone. The aforementioned ether compounds may include, but are not limited to, at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran, or tetrahydrofuran. Other organic solvents may include, but are not limited to, at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolium ketone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, or trioctyl phosphate. This application does not impose any particular limitation on the solvent content in the electrolyte, as long as the purpose of this application is achieved.

[0050] In this application, the electrolyte may also include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery cell, such as additives that improve the overcharge performance of the battery cell, additives that improve the high-temperature or low-temperature performance of the battery cell, etc.

[0051] In addition to electrolyte, a single battery cell also includes a cell assembly. The cell assembly comprises a positive electrode, a separator, and a negative electrode stacked sequentially. The positive electrode, negative electrode, and separator can be formed by stacking or winding to create the cell assembly. This application does not impose any particular limitations on the specific types and structures of the positive electrode, negative electrode, and separator, as long as they meet the purpose of this application. As an example, specific examples of the positive and negative electrodes and separator in the cell assembly are described below.

[0052] 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.

[0053] The positive electrode active layer comprises a positive electrode active material, which can be any material capable of reversibly inserting and de-intercalating Li. + Na + Substances containing alkali metal ions are used to ensure the normal charging and discharging of secondary batteries. For example, the positive electrode active material includes lithium salts, which can be lithium-containing phosphates. Lithium-containing phosphates refer to phosphate materials containing lithium elements and can be detected by any method known in the art. For example, detection can be performed using a combination of X-ray diffraction and energy dispersive spectroscopy, or inductively coupled plasma mass spectrometry. As examples, lithium-containing phosphates include, but are not limited to, at least one of lithium iron phosphate, lithium iron phosphate doped and modified materials, lithium iron phosphate coated and modified materials, lithium manganese phosphate, or lithium manganese iron phosphate. Lithium manganese iron phosphate, as an emerging high-voltage phosphate material, combines safety and high-voltage characteristics.

[0054] For example, the positive electrode active material can also be a high-voltage system with an operating voltage greater than or equal to 4.3V, such as high-nickel ternary materials, high-voltage spinel materials, or lithium-rich manganese-based materials.

[0055] For example, high-nickel ternary materials such as LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiNi 0.8 Co 0.15 Al 0.05 O2 (NCA) and other compounds possess operating voltages of 4.3V~4.6V and high specific capacity, making them ideal cathode choices for high-voltage lithium metal batteries. High-voltage spinel LiNi... 0.5Mn 1.5 O4 operates at a voltage of up to 4.7V, perfectly matching its high voltage stability.

[0056] However, this application is not limited to the materials listed above, and other materials that can be used as positive electrode active materials in battery cells may also be used. These positive electrode active materials may be used alone, or two or more may be used in combination.

[0057] In some embodiments, the positive electrode active layer further includes a positive electrode conductive agent; this application does not limit the type of positive electrode conductive agent, and any known conductive material can be used. Specifically, the positive electrode conductive agent includes, but is not limited to, at least one of the following: acetylene black, Super-P carbon black, amorphous carbon such as needle coke, carbon nanotubes, or graphene.

[0058] In some embodiments, the positive electrode active layer generally also contains a positive electrode binder. There are no particular restrictions on the type of positive electrode binder used in the manufacture of the positive electrode active layer. In the case of the coating method, any material that can be dissolved or dispersed in the liquid medium used in the electrode manufacturing process is acceptable. 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).

[0059] In the positive electrode, there are no particular restrictions on the type of positive electrode current collector; it can be any known material suitable for use as a positive electrode current collector. The positive electrode current collector can be a metal foil or a composite current collector. For example, the metal foil may include, but is not limited to, aluminum foil. The composite current collector may include a base layer and a metal layer located on at least one surface of the base layer. For example, the base layer can be a polymer material base layer, including but not limited to polypropylene (PP) base layer, polyethylene terephthalate (PET) base layer, polybutylene terephthalate (PBT) base layer, polystyrene (PS) base layer, or polyethylene (PE) base layer. The material of the metal layer may include, but is not limited to, aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy. Furthermore, to reduce the electronic contact resistance between the positive electrode current collector and the positive electrode active layer, a conductive additive or conductive coating may be provided on the surface of the positive electrode current collector. Conductive additives include, but are not limited to, carbon and precious metals such as gold, platinum, and silver. The conductive coating may be a mixture of inorganic oxides, conductive agents, and positive electrode binders.

[0060] In preparing the positive electrode, it can be either formulated into a positive electrode slurry, coated onto a positive electrode current collector, and dried to form a positive electrode active layer on the current collector, thus obtaining the positive electrode; or the components in the positive electrode active layer can be dry-mixed, formed into a sheet, and then pressed onto the positive electrode current collector to form the positive electrode active layer, thus obtaining the positive electrode. When using this method to prepare the positive electrode, there are no particular restrictions on the solvent in the positive electrode slurry, as long as it can dissolve or disperse the aforementioned components. Specifically, the solvent in the positive electrode slurry includes, but is not limited to, N-methylpyrrolidone (NMP) and ethylene carbonate (EC).

[0061] The negative electrode includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector, wherein the composition of the negative electrode active layer includes a negative electrode active material. That is, in this application, the negative electrode active layer can be disposed on one surface or on two surfaces in the thickness direction of the negative electrode current collector. Furthermore, in this application, the "surface of the negative electrode current collector" can be the entire area of ​​the negative electrode current collector or only a portion thereof; there are no particular limitations, as long as the purpose of this application is achieved.

[0062] The negative electrode active layer generally contains a negative electrode active material, and this application does not impose any particular limitation on the negative electrode active material. Specifically, the negative electrode active material can be any negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material can be at least one of the following materials, including but not limited to: graphite, carbon materials, silicon-based materials, tin-based materials, or lithium titanate. Graphite can be artificial graphite or natural graphite. Carbon materials can be soft carbon or hard carbon. Silicon-based materials can be selected from at least one of elemental silicon, silicon-oxygen composites, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials can be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other materials that can be used as negative electrode active materials for battery cells can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0063] In some embodiments, the negative electrode active layer typically also contains a negative electrode conductive agent. This application does not particularly limit the type of negative electrode conductive agent, as long as it achieves the purpose of this application. For example, negative electrode conductive agents include, but are not limited to, at least one of acetylene black, Ketjen black, carbon nanotubes, carbon fibers, carbon black, or graphene.

[0064] In some embodiments, the negative electrode active layer may also contain a negative electrode binder and a thickener. This application does not particularly limit the types of negative electrode binders and thickeners, as long as they can achieve the purpose of this application. For example, the negative electrode binder may 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 thickener in the negative electrode slurry may include, but is not limited to, at least one of sodium carboxymethyl cellulose or lithium carboxymethyl cellulose.

[0065] In the negative electrode, the negative electrode current collector can be a metal foil or a composite current collector. For example, the metal foil may include, but is not limited to, copper foil, and this application is not particularly limited. The composite current collector may include a base layer and a metal layer located on at least one surface of the base layer. For example, the base layer may be a polymer material base layer, including but not limited to polypropylene (PP) base layer, polyethylene terephthalate (PET) base layer, polybutylene terephthalate (PBT) base layer, polystyrene (PS) base layer, or polyethylene (PE) base layer. The material of the metal layer may include, but is not limited to, at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy.

[0066] Furthermore, in this application, there are no particular limitations on the thickness of the negative electrode current collector and the negative electrode active layer, as long as the purpose of this application can be achieved. For example, the thickness of the negative electrode current collector is 4μm to 12μm, and the thickness of the single-sided negative electrode active layer is 30μm to 160μm.

[0067] In preparing the negative electrode, the components of the aforementioned negative electrode active layer can be dissolved or dispersed in a liquid solvent to form a negative electrode slurry. This slurry is then coated onto a negative electrode current collector and dried to form a negative electrode active layer, thus obtaining the negative electrode. Alternatively, the components of the negative electrode active layer can be dry-mixed to form a sheet, which is then pressed onto the negative electrode current collector to form the negative electrode active layer, thereby obtaining the negative electrode. Furthermore, when the negative electrode of this application has a first active layer and a second active layer, a layered preparation method can be used, first preparing the first active layer and then preparing the second active layer. The solvent in the negative electrode slurry includes any one of aqueous solvents and organic solvents. Aqueous solvents include, but are not limited to, mixtures of alcohol and water or water itself. Organic solvents include, but are not limited to, aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N,N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide, and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), dimethylformamide, and dimethylacetamide; and aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide. In some other embodiments, when using aqueous solvents, the negative electrode slurry composition may also include a thickener and styrene-butadiene rubber (SBR) emulsion to slurry the negative electrode slurry, thereby adjusting its viscosity. The types of thickeners in the positive electrode slurry include, but are not limited to, at least one of carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and their salts.

[0068] To prevent short circuits, a diaphragm is typically provided between the positive and negative electrodes. In this case, the electrolyte of this application is typically used after permeating into the diaphragm. This application does not impose any particular limitations on the material and shape of the diaphragm, as long as it does not significantly impair the effectiveness of this application. The diaphragm material can be resin, glass fiber, inorganic materials, etc., formed from materials that are stable to the electrolyte of this application. In some embodiments, the diaphragm includes porous sheets or non-woven fabric-like materials with excellent liquid retention properties. Examples of resin or glass fiber diaphragm materials include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, etc. In some embodiments, the polyolefin is polyethylene (PE) or polypropylene (PP). In some embodiments, the polyolefin is polypropylene. The above-mentioned diaphragm materials can be used alone or in any combination.

[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 a single-layer film or a multi-layer composite film, without particular restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular restrictions. The separator can also be a material formed by laminating the above-mentioned materials, examples of which include, but are not limited to, three-layer separators formed by laminating polypropylene, polyethylene, and polypropylene in that order, ceramic-coated separators, high-strength polymer separators, or functionalized composite separators. PP and PE separators typically have a thickness of 12μm to 25μm and a porosity of 30% to 50%, exhibiting good mechanical strength and chemical stability. Ceramic-coated separators are made by coating polyolefin-based membranes with ceramic materials such as Al2O3, SiO2, and TiO2 (coating thickness 2μm to 5μm), improving high-temperature resistance (thermal shut-off temperature >160℃) and puncture resistance. High-strength polymer separators (such as polyimide PI, polyethylene terephthalate PET, and aramid nanofiber separators) have excellent mechanical properties and high-temperature resistance. Functionalized composite membranes (such as membranes with solid electrolyte coatings or lithiophilic coatings) can further improve the stability of lithium deposition.

[0071] The thickness of the separator is arbitrary. In some embodiments, the separator thickness is greater than 1 μm, greater than 5 μm, or greater than 8 μm. In some embodiments, the separator thickness is less than 50 μm, less than 40 μm, or less than 30 μm. When the separator thickness is within the above ranges, insulation and mechanical strength can be ensured, as well as the rate performance and energy density of the secondary battery. In some embodiments of this application, the battery cell structure can be selected as a pouch cell, which is most sensitive to volume changes caused by gas generation and best reflects the technical value of this application.

[0072] The battery cells in this application can be various packaging forms such as button cells, pouch cells, and hard-case cells. The operating voltage range of the battery cells can be set according to the positive and negative electrode systems used, and this application does not impose any particular limitation on this. For example, for the lithium iron phosphate / graphite system, the operating voltage range can be 2.50V~3.65V; for other positive and negative electrode systems, the operating voltage range can be adjusted accordingly based on the material platform. The operating temperature range can be -20℃~60℃.

[0073] The battery cells provided in this application can be widely used in battery fields requiring high energy density and long cycle life, including high-end electric vehicle battery systems, portable electronic devices, and large-scale energy storage power stations. The battery cells provided in this application can achieve large-capacity energy storage, comprehensively improving energy density, cycle life, and safety performance. They can meet the needs of long-term energy storage, achieving 4 hours or more of long-term energy storage, for example, in energy storage scenarios of 5 hours, 6 hours, and 8 hours. Long-term energy storage refers to the ability to continuously discharge at rated power for 4 hours or even longer, or to achieve large-scale, low-cost energy storage for several days or months.

[0074] Accordingly, another embodiment of this application also provides a method for preparing a battery cell, which can be used to manufacture the battery cell provided in the above embodiments, and its preparation process flow diagram is shown below. Figure 1 As shown in the accompanying drawings, the manufacturing method of a battery cell according to another embodiment of this application will be described in detail below. For parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding description of the foregoing embodiment, which will not be described in detail below.

[0075] The method for preparing the battery cell of this application includes the following steps: S100. The positive electrode, separator, and negative electrode are stacked or wound in sequence to form a battery cell assembly.

[0076] This step does not have any special requirements on the stacking method of the positive electrode, separator, and negative electrode; it can be a stacked arrangement or a wound arrangement.

[0077] The positive electrode, separator, and negative electrode in this step can be purchased commercially or made in-house, as described above in this application; and considering that the market and in-house manufacturing processes are already relatively mature, this application will not elaborate on their specific preparation process here.

[0078] S200. The battery cell assembly is placed inside the housing, and the housing contains an electrolyte, which includes a supramolecular cage compound.

[0079] In this step, the supramolecular cage compound can be either commercially available or prepared in-house. As an example, this application provides a method for preparing a supramolecular cage compound; however, the preparation method may vary depending on the type of supramolecular cage compound.

[0080] The preparation method of the organic supramolecular cage compound includes the following steps: A multifunctional organic monomer is dissolved in an organic solvent and then subjected to a condensation reaction to form a supramolecular cage compound; wherein the number of functional groups used in the reaction in the multifunctional organic monomer is not less than 3.

[0081] In the above steps, the multifunctional organic monomers used as reactants can satisfy at least one of the following conditions: 1. Multifunctional organic monomers include triamines and trialdehydes, which can subsequently form Schiff base-type organic cage frameworks.

[0082] 2. Multifunctional organic monomers include terboronic acid and triol, which can subsequently form a borate ester type organic cage framework.

[0083] 3. The multifunctional organic monomers include triamines and triacyl chlorides, or triamines and tricarboxylic acids, which can subsequently form an amide-type organic cage framework. Furthermore, if the multifunctional organic monomers include triamines and tricarboxylic acids, a condensing agent needs to be added to ensure that a condensation reaction can occur between the triamines and tricarboxylic acids.

[0084] Taking a Schiff base-type organic supramolecular cage compound as an example, the preparation method is as follows: a triamine (such as tris(2-aminoethyl)amine or 1,3,5-tris(4-aminophenyl)benzene, etc.) and a trialdehyde (such as 1,3,5-tricarboxyphenyl, etc.) are dissolved in an organic solvent in a stoichiometric ratio. A highly symmetrical cage-like product can be obtained through thermodynamic control; this reaction is a dynamic covalent reaction. The reaction temperature is typically room temperature to 80℃, and the reaction time is 12 h to 72 h. After the reaction is complete, the product can be purified by methods such as filtration, recrystallization, or chromatographic separation.

[0085] The preparation method of organometallic supramolecular cage compounds includes the following steps: A metal salt and a polydentate organic ligand are dissolved in an organic solvent and then self-assembled to form a supramolecular cage compound. The metal salt includes, but is not limited to, at least one of zinc acetate or palladium nitrate; the polydentate organic ligand typically contains two or three N coordination sites, such as at least one of 2,4,6-tris(4-pyridyl)-1,3,5-triazine, 1,3,5-tris(4-pyridyl)benzene, or 4,4'-bipyridine derivatives.

[0086] To ensure that the outer side of the skeleton has modifying groups grafted on, modifying groups are usually introduced into the raw materials (i.e., multifunctional organic monomers) beforehand. In some embodiments, modifying groups can also be introduced after the synthesis of the supramolecular cage compound through etherification, esterification, or acylation reactions at the reactive sites on the periphery of the skeleton. To ensure that the inner side of the skeleton has trapping groups grafted on, it is preferable to achieve this through the pre-design of the building monomers, i.e., assembling a skeleton with trapping groups on the inner wall using monomers with inward-oriented functional groups. Generally, organic supramolecular cage compounds are easier to graft.

[0087] In the preparation of supramolecular cage compounds, the cavity size is mainly controlled by the geometry of the building blocks, the length of the connecting arms, the rigidity of the framework, and the assembly topology. For organic supramolecular cage compounds, increasing the length of the aromatic spacer groups between multifunctional organic monomers usually increases the cavity size, while increasing the rigidity of the framework or decreasing the length of the connecting arms usually decreases the cavity size. For organometallic supramolecular cage compounds, the cavity size can also be controlled by the coordination geometry of the metal nodes, the ligand angles, and the metal-ligand bond lengths. In addition, molecular simulations are used for pre-screening before synthesis, and the cavity size is confirmed after synthesis by combining single-crystal X-ray diffraction or molecular modeling results.

[0088] Homemade supramolecular cage compounds typically require strict quality control before use in electrolyte preparation. Specifically, the purity of the supramolecular cage compound should be above 95%, and further above 98%. Purity can be determined by high-performance liquid chromatography (HPLC) or nuclear magnetic resonance spectroscopy (NMR). The water content of the supramolecular cage compound should be below 100 ppm, and further below 50 ppm. It should be dried in a vacuum drying oven at an appropriate temperature before use. The molecular weight of the supramolecular cage compound can be confirmed by mass spectrometry (MS), the molecular structure by NMR spectroscopy, and the cavity size by single-crystal X-ray diffraction (if a single crystal is available).

[0089] This application also provides a battery device, which includes the aforementioned battery cell, or a battery cell prepared by the aforementioned method. The battery device of this application can take the form of one or more of the following: battery module, battery pack, and energy storage battery.

[0090] Specifically, such as Figures 2-3 As shown, the battery device 100 includes a housing 10 and battery cells 20, with the battery cells 20 housed within the housing 10. The housing 10 provides space for the battery cells 20, and the housing 10 can have various structures.

[0091] In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, and together define a receiving space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, with the first portion 11 covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 together define the receiving space. Figure 3 As shown. The first part 11 and the second part 12 can both be hollow structures with an opening on one side, with the opening side of the first part 11 covering the opening side of the second part 12. Of course, the box 10 formed by the first part 11 and the second part 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0092] In the battery device 100, the battery cell 20 can be a single cell or multiple cells. Multiple battery cells 20 can be connected in series, parallel, or a combination thereof. A combination thereof means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or a combination thereof to form a whole, which is then housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple battery cells 20 first connected in series, parallel, or a combination thereof to form battery modules, which are then connected in series, parallel, or a combination thereof to form a whole, which is also housed within the housing 10.

[0093] The battery device 100 may also include other structures, such as a busbar for making electrical connections between multiple battery cells 20.

[0094] This application also provides an energy storage device, including the aforementioned battery device, wherein the battery device is used to store electrical energy. The energy storage device of this application is not limited to, but is also including, 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).

[0095] This application also provides an electrical device, including the aforementioned battery device, wherein the battery device is used to provide electrical energy. The electrical devices of this application include, but are 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.

[0096] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0097] Example 1 <Preparation of Electrolyte> In an argon-filled glove box with oxygen and water content both below 1 ppm, the organic supramolecular cage compound was added to the base solvent and stirred or sonicated until completely dissolved. Then, lithium salt LiPF6 was added, and stirring continued until the lithium salt was completely dissolved. After thorough mixing, the mixture was allowed to stand to degas and then sealed and stored under an inert atmosphere. The base solvent consisted of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7. Based on the mass of the electrolyte, the lithium salt content was 12%. The types and contents of the organic supramolecular cage compound are shown in Table 1-1, with the remainder being the base solvent.

[0098] <Preparation of Battery Cell Components> The positive electrode, separator, and negative electrode are stacked and wound in sequence to form a battery cell assembly. The positive electrode active material is lithium iron phosphate, the negative electrode active material is graphite, and the separator is a three-layer film of polypropylene, polyethylene, and polypropylene stacked in sequence.

[0099] <Preparation of battery cells> The electrolyte and battery cell assembly are placed inside the housing, allowing the electrolyte to wet the battery cell assembly; after standing, vacuum sealing and formation treatment are performed.

[0100] Examples 2 to 6 Compared to Example 1, the main difference is that the size of the cavity of the organic supramolecular cage compound is adjusted, as shown in Table 1-1.

[0101] Examples 7 to 9 Compared to Example 1, the main difference is that the content of the organic supramolecular cage compound is adjusted, as shown in Table 1-1.

[0102] Examples 10-12 Compared to Example 1, the main difference is that groups are grafted onto the outer or inner wall of the organic supramolecular cage compound, as shown in Table 1-1.

[0103] Examples 13-15 Compared to Example 1, the main difference lies in adjusting the skeleton or type of supramolecular cage compound, as shown in Table 1-1.

[0104] Examples 16-19 Compared to Example 1, the main difference is that the content of the organic supramolecular cage compound is adjusted, as shown in Table 1-1.

[0105] Comparative Example 1 Compared to Example 1, the main difference is that the electrolyte is prepared in the following manner.

[0106] <Preparation of Electrolyte> In an argon-filled glove box with oxygen and water content both below 1 ppm, lithium salt LiPF6 was added to the base solvent and stirred until the lithium salt was completely dissolved. After mixing thoroughly, the mixture was allowed to stand to degas and then sealed and stored under an inert atmosphere. The base solvent consisted of EC and EMC in a volume ratio of 3:7, and the lithium salt content was 12% based on the mass of the electrolyte.

[0107] Comparative Example 2 Compared to Example 1, the main difference is that the electrolyte is prepared in the following manner.

[0108] In an argon-filled glove box with oxygen and water content both below 1 ppm, FEC was added to the base solvent and stirred or sonicated until completely dissolved. Then, lithium salt LiPF6 was added, and stirring continued until the lithium salt was completely dissolved. After thorough mixing, the mixture was allowed to stand to degas and then sealed and stored under an inert atmosphere. The base solvent consisted of EC and EMC in a volume ratio of 3:7. Based on the mass of the electrolyte, the lithium salt content was 12%, the FEC addition was 2% by volume, and the remainder was the base solvent.

[0109] Test methods and equipment High-temperature storage thickness expansion rate test After formation and capacity testing, the battery cells were charged to 100% SOC and placed in a constant temperature chamber at 60℃±2℃ for 7 days. The dimensions of the battery cells in the maximum thickness direction were measured using a micrometer before and after storage. The expansion rate was calculated using the following formula: Expansion rate (%) = (T1-T0) / T0×100%, where T0 is the battery thickness before storage and T1 is the battery thickness after storage. At least three parallel samples were tested in each group, and the average value was taken.

[0110] Alternatively, parallel samples can be disassembled, and the evolved gas can be collected using a closed gas collection device, and the gas production rate (mL / Ah) can be obtained by normalizing it according to the rated capacity.

[0111] High-temperature cycling capacity retention test Under conditions of 45℃±2℃, the battery cells that have completed formation and capacity grading were subjected to constant current and constant voltage charge-discharge cycle tests at a 1C / 1C rate within a range of a charging cut-off voltage of 3.65V and a discharging cut-off voltage of 2.50V, for 300 cycles. The capacity retention rate (%) was calculated as the ratio of the discharge capacity at the 300th cycle to the discharge capacity at the 1st cycle.

[0112] The specific test results are shown in the table below.

[0113] Table 1-1

[0114] It can be seen that, compared with Comparative Example 1 without the addition of supramolecular cage compound, the thickness expansion rate of each example with the addition of supramolecular cage compound was significantly reduced after high-temperature storage at 60℃ for 7 days, and the capacity retention rate after 300 cycles at 45℃ was improved. This indicates that the supramolecular cage compound can effectively capture side reaction gas molecules, reduce the concentration of free gas in the electrolyte, thereby inhibiting bubble nucleation and growth, and improving the overall performance of the battery cell.

[0115] Furthermore, as shown in Examples 1 to 6, when the cavity size is in the range of 0.45 nm to 0.55 nm, the expansion rate is the lowest, the capacity retention rate is the highest, and the overall effect is optimal. This is because this size range is well matched with carbon dioxide (kinetic diameter approximately 0.33 nm) and ethylene (kinetic diameter approximately 0.42 nm). A cavity size that is too small (less than 0.30 nm) will increase the difficulty for gas molecules to enter, while a cavity size that is too large (greater than 1.00 nm) will easily reduce the host-guest interaction strength, affecting the capture efficiency.

[0116] Furthermore, as shown in Examples 1 and 7-9, when the amount of supramolecular cage compound added is in the range of 0.5% to 2.0%, both gas capture capacity and electrolyte bulk performance can be balanced. If the amount added is too low (less than 0.1%), the capture capacity will be insufficient; if the amount added is too high (greater than 5.0%), the cycle performance may decrease slightly due to the influence on electrolyte viscosity and ion transport.

[0117] Furthermore, as shown in Examples 1 and 10-12, the outer wall modification groups are beneficial for improving the dispersion stability of cage molecules in the electrolyte, while the inner wall trapping groups are beneficial for enhancing the effect on target gas molecules. Example 12, which introduces both outer wall modification groups and inner wall trapping groups, performs best, indicating that the synergistic effect of the two types of groups can further improve the swelling suppression effect. Compared with Comparative Example 2, which uses the traditional film-forming additive FEC, FEC improves the high-temperature cycling capacity retention to some extent, but its effect on suppressing high-temperature storage swelling is limited. This is because FEC, as a film-forming additive, acts on the electrode interface rather than the gas itself, and cannot prevent the nucleation and bubble growth process of the generated gas molecules after reaching supersaturation. The supramolecular cage compounds in the embodiments of this application can directly act on the gas molecules themselves, capturing and fixing them inside the cavity through host-guest recognition, thus having a greater advantage in suppressing swelling.

[0118] Furthermore, as shown in Examples 1 and 13-15, except for the Schiff base type organic cage, the borate ester type organic cage, the amide type organic cage, and the metal-organic supramolecular cage can all reduce the thickness expansion rate after standing at 60°C for 7 days and improve the capacity retention rate after cycling at 45°C for 300 cycles. This indicates that supramolecular cage compounds of different skeleton types can capture side reaction gases through cavity structures, thereby improving the high-temperature storage and cycling performance of battery cells. Among them, the overall effect of the amide type organic cage is close to that of the Schiff base type organic cage. Although the overall effect of the borate ester type organic cage and the metal-organic supramolecular cage is slightly weaker than that of the Schiff base type organic cage, they are still significantly better than Comparative Example 1, which did not add supramolecular cage compounds.

[0119] Furthermore, as shown in Examples 16-19, when the amount of supramolecular cage compound added is less than 0.01%, the gas trapping capacity is insufficient, and the improvement in swelling suppression effect and capacity retention is limited. When the addition amount reaches 0.01%, compared with the out-of-range sample of 0.008%, the thickness expansion rate is significantly reduced and the capacity retention rate is improved, indicating that 0.01% as the lower limit is more effective. When the addition amount exceeds 10%, the cycle performance and overall effect may decrease due to the increase in electrolyte viscosity or the impact on ion transport; the 10% sample has better overall performance than the out-of-range sample of 12%, indicating that 10% as the upper limit is more effective. In summary, the statement that "the addition amount range of 0.01% to 10% can more effectively suppress gas bubble formation and improve the safety and performance of battery cells" is supported by both the endpoint and the out-of-range control.

[0120] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made 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, include: A battery cell assembly, wherein the battery cell assembly is formed by stacking or winding a positive electrode, a separator, and a negative electrode; The housing, in which the battery cell assembly is located; An electrolyte is located within the housing, and the electrolyte includes a supramolecular cage compound having a framework that surrounds and forms a cavity. The supramolecular cage compound includes at least one of an organic supramolecular cage compound or a metal-organic supramolecular cage compound.

2. The battery cell according to claim 1, characterized in that, The size of the cavity is 0.3 nm to 1.0 nm.

3. The battery cell according to claim 1, characterized in that, The framework of the organic supramolecular cage compound includes at least one of a Schiff base type organic cage framework, a borate ester type organic cage framework, or an amide type organic cage framework.

4. The battery cell according to claim 1, characterized in that, The framework of the metal-organic supramolecular cage compound is formed by metal nodes and organic ligands connected by coordination bonds.

5. The battery cell according to claim 4, characterized in that, The metal element in the metal node includes at least one of zinc, copper, or palladium.

6. The battery cell according to claim 1, characterized in that, Based on the mass of the electrolyte, the mass content of the supramolecular cage compound is 0.01% to 10%.

7. The battery cell according to claim 1, characterized in that, The outer wall of the skeleton of the supramolecular cage compound is grafted with a modifying group, which includes at least one of C1-C6 fluoroalkyl, C1-C6 fluoroalkoxy, C1-C6 alkoxy, or C2-C6 acyloxy.

8. The battery cell according to claim 1, characterized in that, The inner wall of the skeleton of the supramolecular cage compound is grafted with a trapping group, which includes at least one of pyridyl, pyrazinyl, triazineyl or naphthyl.

9. A method for preparing a single battery cell, characterized in that, Includes the following steps: The positive electrode, separator, and negative electrode are stacked or wound in sequence to form a battery cell assembly. The battery cell assembly is disposed within a housing, the housing contains an electrolyte, and the electrolyte includes a supramolecular cage compound, the supramolecular cage compound including at least one of an organic supramolecular cage compound or a metal-organic supramolecular cage compound. The preparation method of the supramolecular cage compound includes the following steps: A multifunctional organic monomer is dissolved in an organic solvent and then subjected to a condensation reaction to form the supramolecular cage compound, wherein the number of functional groups used in the reaction in the multifunctional organic monomer is not less than 3. Alternatively, metal salts and polydentate organic ligands can be dissolved in an organic solvent and then self-assembled to form the supramolecular cage compound.

10. The method for preparing a battery cell according to claim 9, characterized in that, The multifunctional organic monomer satisfies at least one of the following conditions: a. The multifunctional organic monomers include triamines and trialdehydes; b. The multifunctional organic monomers include triboronic acid and triol; c. The multifunctional organic monomer includes a triamine and a triacyl chloride, or the multifunctional organic monomer includes a triamine and a tricarboxylic acid.

11. A battery device, characterized in that, It includes battery cells as described in any one of claims 1 to 8, or battery cells prepared by the manufacturing method of battery cells as described in any one of claims 9 to 10.

12. An energy storage device, characterized in that, Includes the battery device as described in claim 11, wherein the battery device is used to store electrical energy.

13. An electrical appliance, characterized in that, Includes the battery device as described in claim 11, the battery device being used to provide electrical energy.

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