A battery cell, a method of manufacturing the same, a battery device, a power consuming device, and a gel electrolyte

Abstract

The application relates to the technical field of batteries, and provides a battery monomer, a preparation method of the battery monomer, a battery device, a power utilization device and a gel electrolyte. The battery monomer comprises an electrode assembly and a gel electrolyte, the gel electrolyte comprises a polymer matrix and an electrolyte, and the polymer matrix comprises a first structural unit and a second structural unit. In the battery monomer provided by the application, the first structural unit and the second structural unit can construct the electrolyte of the gel system through a polymerization reaction, a three-dimensional skeleton structure composed of the polymer matrix exists in the electrolyte, the electrolyte is bound in the three-dimensional skeleton of the gel system through an anchoring structure, that is, the electrolyte is bound in a relatively fixed area, therefore, the electrolyte is not prone to accumulating in a large amount in a tab or an Overhang area, the formation of lithium dendrites and powdered lithium can be effectively inhibited, the risk of internal short circuit and thermal runaway is reduced, and the reliability of the battery is effectively improved.

Description

Technical Field

[0001] This application belongs to the field of battery technology, and particularly relates to a battery cell and its preparation method, battery device, power-consuming device, and gel electrolyte. Background Technology

[0002] Secondary batteries have high capacity and are therefore widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools.

[0003] With the development of applications for secondary batteries, the requirements for secondary batteries are gradually increasing, and the reliability of secondary batteries needs to be further improved.

[0004] The above statements are for the purpose of providing background information in relation to this application only and do not necessarily constitute prior art. Summary of the Invention

[0005] The purpose of this application is to provide a battery cell and its preparation method, battery device, power supply device, and gel electrolyte, aiming to solve the problem of poor reliability of battery cells.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a battery cell including an electrode assembly and a gel electrolyte. The gel electrolyte includes a polymer matrix and an electrolyte solution. The polymer matrix includes a first structural unit and a second structural unit. The first structural unit has the structural formula shown in formula (I), and the second structural unit has the structural formula shown in formula (II).

[0008]

[0009] The first structural unit and the second structural unit are connected by at least one chemical bond selected from urethane bonds, urea bonds, carbon-sulfur single bonds, carbon-carbon single bonds, and ester bonds.

[0010] Among them, M1, M2, M3, M4, M5, and M6 each independently include anchoring structures; n is any natural number from 2 to 2000, and m is any natural number from 20 to 2000.

[0011] In the technical solution of this application, the first structural unit and the second single structural unit can construct the electrolyte of the gel system, which has a three-dimensional skeleton structure composed of a polymer matrix. The electrolyte is bound in the three-dimensional skeleton of the gel system through the anchoring structure, that is, the electrolyte is bound in a relatively fixed area. On the one hand, this can effectively reduce the volatility of the electrolyte during battery cycling, reduce the amount of electrolyte volatilization, and thus effectively avoid problems such as abnormal electrolyte distribution caused by the accumulation after volatilization. This helps to improve the relative stability of the internal electrochemical environment of the battery. On the other hand, this means that the electrolyte is not easy to move and diffuse freely, making it less likely for the electrolyte to diffuse to the tab or overhang area, and even less likely to accumulate in large quantities in the tab or overhang area. This can effectively suppress the formation of lithium dendrites and lithium powder, reduce the risk of internal short circuit and thermal runaway, and thus effectively improve the reliability of the battery. Meanwhile, the gel electrolyte can form a tight and stable interface with the negative electrode. This stable interface reduces defects and micro-gaps at the interface, making the transport of lithium ions at the interface more uniform and orderly, thereby improving the stability of the electrode-gel electrolyte interface. Due to the improved interface stability, the local heat generation caused by charge accumulation and uneven reaction at the interface is reduced, reducing the early heat generation sources and the rate of heat accumulation. Under the same charge and discharge conditions, the battery can withstand higher temperatures without entering the self-heating state, that is, delaying the occurrence of self-heating. This delay gives the battery a larger temperature safety margin during normal operation, that is, the self-heating temperature is increased, thereby improving the safety and reliability of the battery during use.

[0012] In some embodiments, n is any natural number from 2 to 10.

[0013] By controlling the value of n within the above range, a suitable ratio of flexible and electrophilic ether oxygen segments to rigid benzene ring structures can be achieved, resulting in better mechanical properties of the gel electrolyte.

[0014] In some embodiments, m is any natural number from 90 to 120.

[0015] By controlling the value of m within the above range, a gel electrolyte network can be formed, which has a relatively suitable three-dimensional skeleton structure.

[0016] In some embodiments, the anchoring structure includes at least one of hydrogen atom, halogen atom, hydroxyl group, amino group, substituted alkyl group and alkoxy group, wherein the substituent in the substituted alkyl group includes hydroxyl group, amino group or halogen atom.

[0017] The atoms or groups in these anchoring structures can interact with solvent molecules and anions in the electrolyte, which allows the electrolyte to be firmly bound within the three-dimensional framework of the gel system.

[0018] In some embodiments, the molar ratio of the first structural unit to the second structural unit is 2:(3-5).

[0019] Within this ratio range, the first structural unit can be interconnected with the second structural unit to form a polymer matrix with a three-dimensional network structure.

[0020] In some embodiments, the polymer matrix comprises at least one of the polymers shown in Formula III-1 to Formula III-4:

[0021]

[0022]

[0023] Where k is a natural number greater than or equal to 10, and R is a C1-C20 alkyl group.

[0024] From a spatial perspective, these polymers extend in multiple directions, which means that they have a three-dimensional network structure. At the same time, these polymers have high chemical stability, good adhesion and flexibility, and excellent mechanical properties. Therefore, when these polymers are applied to gel electrolyte systems, the gel electrolyte can form a tight and stable bonding interface with the negative electrode, thereby effectively improving the safety and reliability of the battery during use.

[0025] In some embodiments, the content of the polymer matrix is ​​0.5%-30% based on the total weight of the gel electrolyte.

[0026] An appropriate amount of polymer matrix endows gel electrolytes with good mechanical strength and high electrochemical stability. At the same time, it can form an effective three-dimensional network structure in the gel electrolyte, thereby guiding the migration path of ions, making ion conduction more orderly, and thus forming a good ion transport channel.

[0027] In some embodiments, the electrolyte comprises a solvent and a lithium salt, wherein the solvent comprises an ether solvent.

[0028] The ether bonds in ether solvents can interact with the anchoring structures in the polymer matrix, thereby effectively binding the electrolyte within the three-dimensional framework structure formed by the polymer matrix.

[0029] In some embodiments, the anchoring structure in the polymer matrix is ​​bonded to the solvent and anions in the electrolyte through at least one chemical bond selected from hydrogen bonds and coordination bonds.

[0030] Hydrogen bonds and coordination bonds can tightly bind the electrolyte to the polymer matrix, thereby achieving effective confinement of the electrolyte.

[0031] In some embodiments, the solvent comprises a main solvent and a diluent, wherein the main solvent comprises at least one of chain ether solvents and cyclic ether solvents; and / or, the diluent comprises at least one of aromatic solvents, fluoroalkane solvents, and fluoroether solvents.

[0032] A locally high-concentration electrolyte is formed by using a main solvent and a diluent. This electrolyte can form an inorganic-rich SEI film on the negative electrode surface. This SEI film has good mechanical and chemical stability, which can effectively prevent further reactions between the electrode and the electrolyte, inhibit the growth of lithium dendrites, and thus improve the cycle life and safety of the battery.

[0033] In some embodiments, based on the total weight of the solvents, the content of the main solvent is 10%-80%, and the content of the diluent is 20%-90%.

[0034] By controlling the content of the main solvent and diluent within the above range, the solvation structure in the electrolyte can be adjusted, thereby improving the ionic conductivity of the electrolyte and the cycle performance of the battery.

[0035] In some embodiments, the molar concentration of the lithium salt in the electrolyte is 0.5 mol / L to 6 mol / L.

[0036] Within this range, the electrolyte exhibits good ionic conductivity, which helps increase the number of freely moving ions, thereby improving the battery's charge and discharge efficiency.

[0037] In some embodiments, the electrode assembly includes a negative electrode sheet, the negative electrode sheet includes a negative electrode material, and the negative electrode material includes any one of pure lithium and lithium alloy.

[0038] These negative electrode materials have high specific capacity and low electrode potential, which helps to improve the energy density of the battery.

[0039] Secondly, this application provides a method for preparing a battery cell, comprising the following steps:

[0040] The first and second monomers are added to the electrolyte to obtain the gel electrolyte precursor solution;

[0041] The above-mentioned gel electrolyte precursor solution is injected into the electrode assembly, and then a polymerization reaction is carried out to make the above-mentioned gel electrolyte precursor solution gel electrolyte, thus obtaining a battery cell.

[0042] The structural formula of the first monomer is shown in formula (I), and the structural formula of the second monomer is shown in formula (II).

[0043]

[0044] Wherein, R1, R2, R3, R4, and R5 each independently include any one of vinyl, hydroxy, amino, mercapto, isocyanate, and acrylate groups; at least one group among R1, R2, R3, R4, and R5 contains a double bond; at least one group among R4 and R5 can undergo a condensation reaction with at least one group among R1, R2, and R3; and M1, M2, M3, M4, M5, and M6 each independently include an anchoring structure.

[0045] n is any natural number from 2 to 2000, and m is any natural number from 20 to 2000.

[0046] The method for preparing a battery cell provided in this application involves first adding a first monomer and a second monomer to an electrolyte, and then injecting the resulting gel electrolyte precursor solution into an electrode assembly. Through a polymerization reaction, the first monomer and the second monomer achieve a relatively thorough in-situ polymerization and solidification reaction to form a gel electrolyte, thereby effectively preparing a battery cell with the performance described above.

[0047] In some embodiments, at least one of the groups R1, R2, and R3 in the first monomer is an isocyanate group, and at least one of the groups R4 and R5 in the second monomer is selected from either hydroxyl or amino groups.

[0048] The isocyanate group (-NCO) is a relatively reactive functional group that can undergo polycondensation reactions with hydroxyl (-OH) and amino (-NH2). This means that the first monomer containing the isocyanate group can react with the second monomer containing amino and hydroxyl groups to form a polymer matrix.

[0049] In some embodiments, at least one of the groups R1, R2, and R3 in the first monomer is vinyl, and at least one of the groups R4 and R5 in the second monomer is selected from any one of mercapto, vinyl, and acrylate groups.

[0050] Vinyl (-CH=CH2), thiol (-SH), and acrylate (-COO-CH=CH2) are all reactive functional groups. Therefore, the first monomer containing vinyl can react with the second monomer containing thiol, vinyl, and acrylate to form a polymer matrix.

[0051] In some embodiments, at least one of the groups R1, R2, and R3 in the first monomer is an acrylate group, and at least one of the groups R4 and R5 in the second monomer is selected from either vinyl or acrylate groups.

[0052] Acrylate groups (-COO-CH=CH2) and vinyl groups (-CH=CH2) are both active functional groups capable of polymerization. Therefore, a first monomer containing acrylate groups and a second monomer containing vinyl and acrylate groups can react to form a polymer matrix.

[0053] In some embodiments, the anchoring structure includes at least one of a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a substituted alkyl group, and a chain alkoxy group, wherein the substituent in the substituted alkyl group includes a hydroxyl group, an amino group, or a halogen atom.

[0054] These anchoring structures can interact with solvent molecules and anions in the electrolyte, which allows the electrolyte to be firmly bound within the three-dimensional framework of the gel system.

[0055] In some embodiments, the conditions for the polymerization reaction include heat treatment at 40°C-80°C for 10-24 hours.

[0056] Under these heat treatment conditions, the active functional groups of the first and second monomers react to form a polymer matrix with a three-dimensional network structure.

[0057] In some embodiments, the molar ratio of the first structural unit to the second structural unit is 2:(3-5).

[0058] Within this molar ratio range, the groups such as R1, R2, and R3 contained in the first monomer and the groups such as R4 and R5 contained in the second monomer can react completely, thus minimizing monomer residue.

[0059] Thirdly, this application provides a battery device including multiple battery cells of the above embodiments.

[0060] Fourthly, this application provides an electrical device, including a single battery cell as described in the above embodiments or a battery device as described in the above embodiments.

[0061] Fifthly, this application provides a gel electrolyte, including a polymer matrix and an electrolyte, wherein the polymer matrix includes a first structural unit and a second structural unit, the first structural unit having the structural formula shown in formula (I), and the second structural unit having the structural formula shown in formula (II).

[0062]

[0063] The first structural unit and the second structural unit are connected by at least one chemical bond selected from urethane bonds, urea bonds, carbon-sulfur single bonds, carbon-carbon single bonds, and ester bonds.

[0064] Where * represents a connection point; M1, M2, M3, M4, M5, and M6 each independently include an anchoring structure; n is any natural number from 2 to 2000, and m is any natural number from 20 to 2000.

[0065] The gel electrolyte provided in this application comprises a first structural unit and a second structural unit that can construct a gel system electrolyte. Internally, it contains a three-dimensional framework structure composed of a polymer matrix. Since both the first and second structural units contain benzene ring structures, the rigidity of the benzene rings mechanically inhibits the growth of lithium dendrites and withstands their penetration, giving the gel electrolyte high structural stability and mechanical strength. This reduces the problem of internal short circuits caused by lithium dendrite growth, thereby improving battery reliability. The linear components, such as ether oxygen segments, in the second structural unit endow the gel electrolyte with high flexibility. This flexibility allows the gel electrolyte to adapt well to volume changes in the negative electrode material caused by the insertion and extraction of active ions, thus helping to maintain relatively close contact between the gel electrolyte and the negative electrode sheet. This allows for smooth lithium ion transport between the negative electrode and the gel electrolyte. Furthermore, the flexible gel electrolyte can form a flexible interface with the negative electrode sheet. When the volume of the negative electrode material changes, the gel electrolyte can buffer the stress caused by this change through flexible deformation, making the SEI film less prone to breakage and improving its stability. This reduces the consumption of active lithium, lowers the battery's internal resistance, and improves the battery's cycle life and safety.

[0066] In some embodiments, the anchoring structure described above includes at least one of a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a substituted alkyl group, and a chain alkoxy group, wherein the substituent in the substituted alkyl group includes a hydroxyl group, an amino group, or a halogen atom.

[0067] These anchoring structures can interact with solvent molecules and anions in the electrolyte, which allows the electrolyte to be firmly bound within the three-dimensional framework of the gel system.

[0068] In some embodiments, the electrolyte comprises a solvent and a lithium salt, wherein the solvent includes ether solvents.

[0069] The ether bonds in ether solvents can interact with the anchoring structures in the polymer matrix, thereby effectively binding the electrolyte within the three-dimensional framework structure formed by the polymer matrix. Attached Figure Description

[0070] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0071] Figure 1 This is an exploded view of the battery device provided in the embodiments of the present invention / application;

[0072] Figure 2 This is an exploded view of a battery cell provided in the embodiments of the present invention / application;

[0073] Figure 3 This is a schematic diagram of one embodiment of an electrical device that uses a battery cell as a power source, as described in the present application.

[0074] The following are the labeling elements in the figure:

[0075] 100. Battery device;

[0076] 10. Box body; 11. First box body; 12. Second box body;

[0077] 20. Battery cell modules;

[0078] 30. Battery cell, 31. Casing, 32. Electrode assembly, 33. Cover plate. Detailed Implementation

[0079] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0080] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0081] 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.

[0082] 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.

[0083] 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: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0084] 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.

[0085] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0086] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0087] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0088] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0089] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0090] In the embodiments of this application, the term "T1" represents the self-generated heat temperature, which is the temperature point at which the battery's heat release rate reaches or exceeds 0.02°C / min. At this temperature, the heat generated by the internal reaction of the battery is sufficient to cause the battery's own temperature to begin to rise continuously, no longer relying on an external heat source. It represents the critical state in which the battery transitions from external heat-dominated temperature rise to self-heat-dominated temperature rise.

[0091] In the embodiments of this application, the term "T2" represents the thermal runaway temperature, which is the temperature point at which the battery's heat release rate reaches or exceeds 60°C / min. It is the marker that the battery transitions from normal thermal behavior to a thermal runaway state. At this temperature, the exothermic reaction occurring inside the battery becomes extremely intense, and the generated heat causes the battery temperature to rise sharply. This rapid and uncontrollable temperature rise is a typical characteristic of the thermal runaway stage.

[0092] In this application embodiment, the term "T3" represents the battery's highest temperature, which is the highest temperature reached by the battery after thermal runaway, during the process of combustion, explosion, or other runaway behavior, as detected by detection methods. It represents the peak temperature reached by the battery under the extreme dangerous condition of thermal runaway, and is the highest point of temperature change during the entire thermal runaway process.

[0093] In the embodiments of this application, "overhang" refers to, for example, during the electrode preparation process of a lithium-ion battery, when the active material is coated onto aluminum foil (positive electrode current collector) or copper foil (negative electrode current collector), a portion of the active material layer may extend beyond the edge of the current collector. This portion of the negative electrode active layer extending beyond the positive electrode active layer in both length and width is a safety redundancy designed at the cell level to ensure battery safety and reliability. In traditional lithium-ion batteries, this is to prevent lithium ion deposition at the negative electrode, while in this application, it is to prevent direct deposition of lithium ions on the copper current collector. This is because direct deposition of lithium ions on the current collector leads to corrosion of the current collector and uneven deposition on the surface and edges, reducing the durability of the current collector and the reliability of the battery. Therefore, this designed safety redundancy is called "overhang."

[0094] In the embodiments of this application, SEI film is short for "solid electrolyte interface", which refers to a solid electrolyte interface film with solid electrolyte characteristics. That is, during the first charge and discharge process of a liquid lithium-ion battery, the electrode material and the electrolyte react at the solid-liquid interface to form a passivation film covering the surface of the negative electrode material.

[0095] In the embodiments of this application, "anchoring structure" refers to atoms or groups in a structural formula that can stably fix a part or the entire molecule of a molecule at a specific position or in a specific environment through specific interactions.

[0096] In the embodiments of this application, "alkyl" refers to a saturated hydrocarbon containing a primary (normal) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof. Phrases containing this term, such as "C1-C20 alkyl," refer to alkyl groups containing 1 to 20 carbon atoms, and each occurrence can independently be C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl, C10 alkyl, C11 alkyl, C12 alkyl, C13 alkyl, C14 alkyl, C15 alkyl, C16 alkyl, C17 alkyl, C18 alkyl, C19 alkyl, or C20 alkyl.

[0097] Gel electrolytes are electrolyte materials that fall between solid electrolytes and liquid electrolytes. They possess the advantages of solid electrolytes, such as being less prone to short circuits and less likely to leak electrolytes. In addition, gel polymer electrolytes have good processability, allowing for flexible and diverse battery designs, which greatly promotes the development and large-scale application of the battery industry.

[0098] However, when gel electrolytes are used in battery systems, after multiple cycles, the interfacial contact between the battery electrodes and the gel electrolyte deteriorates, making it unable to adapt to the volume changes of the negative electrode during charging and discharging. This hinders tight bonding between the two, inevitably leading to low interfacial stability and a series of problems detrimental to battery performance and safety, such as lithium dendrite formation and increased interfacial impedance. If only linear structures are used to improve the flexibility of the gel electrolyte, such as (meth)acrylate monomers, the structural limitations restrict the construction to simple one- or two-dimensional structures, failing to create a three-dimensional conductive network. This severely restricts ion transport paths within the gel electrolyte, resulting in low ionic conductivity and significantly limiting the application and development of gel electrolytes in related fields.

[0099] Based on this, this application provides a battery cell including an electrode assembly and a gel electrolyte. The gel electrolyte includes a polymer matrix and an electrolyte solution. The polymer matrix includes a first structural unit and a second structural unit. The structural formula of the first cell is shown in formula (I), and the structural formula of the second cell is shown in formula (II).

[0100]

[0101] The first structural unit and the second structural unit are connected by at least one chemical bond selected from the following: urethane bond (-NH-CO-O-), urea bond (-NH-CO-NH-), carbon-sulfur single bond (-CS-), carbon-carbon single bond (-CC-), and ester bond (-COO-).

[0102] Where * represents a connection point; M1, M2, M3, M4, M5, and M6 each independently include an anchoring structure; n is any natural number from 2 to 2000, and m is any natural number from 20 to 2000.

[0103] In this application's technical solution, since both the first and second structural units contain benzene ring structures, the rigidity of the benzene rings can hinder the growth of lithium dendrites at the microscopic level. Furthermore, the rigid network formed by the benzene rings is not easily penetrated or destroyed by lithium dendrites. This mechanically inhibits lithium dendrite growth and also withstands dendrite puncture, giving the gel electrolyte high structural stability and mechanical strength. This reduces the problem of internal short circuits in the battery caused by lithium dendrite growth, thereby improving battery reliability. Additionally, the linear portions, such as ether oxygen segments, contained in the second structural unit can impart high flexibility to the gel electrolyte. The flexibility of the gel electrolyte allows it to adapt well to the volume changes in the negative electrode material caused by the insertion and extraction of active ions. This helps the gel electrolyte maintain a relatively tight contact with the negative electrode, enabling smooth lithium ion transport between the negative electrode and the gel electrolyte. In addition, the flexible gel electrolyte can form a flexible interface with the negative electrode. When the volume of the negative electrode material changes, the gel electrolyte can buffer the stress caused by this change through flexible deformation, making the SEI film less prone to breakage and improving its stability. This reduces the consumption of active lithium, lowers the battery's internal resistance, and improves the battery's cycle life and safety.

[0104] Therefore, gel electrolytes possess high elasticity and good mechanical strength, which can effectively suppress volume changes in the negative electrode material during charging and discharging, and exert a counterforce on lithium deposition. This prevents lithium deposition from occurring randomly and disorderly, instead guiding it towards a more uniform deposition morphology. A uniform lithium deposition morphology effectively reduces the specific surface area of ​​lithium, thereby decreasing its reactivity. This reduces the chance of side reactions between lithium and other components such as the electrolyte, thus significantly improving battery safety.

[0105] The first and second structural units can construct the electrolyte of the gel system, which contains a three-dimensional framework structure composed of a polymer matrix. The electrolyte is bound within the three-dimensional framework of the gel system through anchoring structures, that is, the electrolyte is bound to a relatively fixed area. On the one hand, this can effectively reduce the volatility of the electrolyte during battery cycling, reduce the amount of electrolyte volatilization, and thus effectively avoid problems such as abnormal electrolyte distribution caused by re-accumulation after volatilization. This helps to improve the relative stability of the internal electrochemical environment of the battery. On the other hand, this means that the electrolyte is not easy to move and diffuse freely, making it less likely for the electrolyte to diffuse to the tab or overhang region, and even less likely to accumulate in large quantities in the tab or overhang region. This can effectively suppress the formation of lithium dendrites and lithium powder, reduce the risk of internal short circuits and thermal runaway, and thus effectively improve the reliability of the battery. Meanwhile, the gel electrolyte can form a tight and stable interface with the negative electrode. This stable interface reduces defects and micro-gaps at the interface, making the transport of lithium ions at the interface more uniform and orderly, thereby improving the stability of the entire negative electrode-gel electrolyte interface. Due to the improved interface stability, the local heat generation caused by charge accumulation and uneven reaction at the interface is reduced, reducing the early heat generation sources and the rate of heat accumulation. Under the same charge and discharge conditions, the battery can withstand higher temperatures without entering the self-heating state, that is, delaying the occurrence of self-heating. This delay gives the battery a larger temperature safety margin during normal operation, that is, the self-heating temperature is increased, thereby improving the safety and reliability of the battery during use.

[0106] Meanwhile, the three-dimensional framework structure composed of a polymer matrix exists in the electrolyte of the gel system. This three-dimensional structure can act as a buffer and regulator to a certain extent, allowing lithium ions to diffuse relatively uniformly within it, thus effectively eliminating the concentration gradient caused by charging and discharging. Because lithium ions can diffuse and deposit relatively uniformly, it is less likely to form excessively high current densities locally, thereby suppressing the formation of lithium dendrites.

[0107] Furthermore, the three-dimensional framework structure of the polymer matrix contains abundant and interconnected channels. These channels provide continuous and stable pathways for ion transport, allowing ions to migrate smoothly and reducing energy loss and migration resistance caused by interruptions or blockages in the transport path. This effectively improves the ion migration rate in the gel electrolyte. On the other hand, ions can also migrate along the surface or interior of the polymer material that constitutes the three-dimensional network. This multi-dimensional migration mode effectively promotes the ion migration rate in the gel electrolyte. Based on this, ions can migrate rapidly inside the battery, thereby effectively improving charge / discharge capacity and energy density.

[0108] In some embodiments, n is any natural number from 2 to 10. For example, n can be typical but not limiting values ​​such as 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0109] The ether oxygen segment is the key part that provides flexibility in the gel electrolyte, while the benzene ring structure provides rigidity. By controlling the n value within the above range, the gel electrolyte can balance its flexibility and rigidity. That is, the gel electrolyte not only has sufficient flexibility to adapt to the volume changes caused by the intercalation and deintercalation of the negative electrode material, thus helping the gel electrolyte to maintain a relatively close contact with the negative electrode and improve interface stability, but also relies on the rigid structure to provide the necessary strength and shape stability, thereby giving the gel electrolyte good mechanical properties and meeting the mechanical performance requirements of gel electrolytes in battery and other application scenarios.

[0110] In some embodiments, m is any natural number from 90 to 120. For example, m can be typical but not limiting values ​​such as 90, 92, 95, 98, 100, 102, 105, 107, 110, 112, 115, 117, and 120.

[0111] By controlling the value of m within the above range, a gel electrolyte network can be formed, which has a relatively suitable three-dimensional skeleton structure.

[0112] In some embodiments, the anchoring structure described above includes at least one of hydrogen atom, halogen atom, hydroxyl group, amino group, substituted alkyl group and alkoxy group, wherein the substituents in the substituted C1-C5 alkyl group include hydroxyl group, amino group or halogen atom.

[0113] For example, the alkyl group in the substituted alkyl group can be a C1-C5 alkyl group.

[0114] For example, substituted alkyl groups include amino-substituted alkyl groups, hydroxyl-substituted alkyl groups, and fluorine-substituted alkyl groups.

[0115] These anchoring structures can interact with solvent molecules and anions in the electrolyte, allowing the electrolyte to be firmly bound within the three-dimensional framework of the gel system. For example, hydrogen atoms can interact with solvent molecules and anions in the electrolyte through hydrogen bonds; halogens have strong electronegativity and carry a partial negative charge, thus attracting cations in the electrolyte through electrostatic interactions; hydroxyl groups can form hydrogen bonds with oxygen atoms in solvent molecules in the electrolyte, and can also form hydrogen bonds with anions in the electrolyte; amino groups have lone pairs of electrons and hydrogen atoms, thus enabling electrostatic interactions with anions in the electrolyte; alkyl groups (such as methyl, ethyl, propyl, etc.) themselves have a certain steric hindrance effect, and when hydroxyl or amino groups replace these alkyl groups, the alkyl groups can regulate the hydroxyl group. The spatial distribution of amino groups allows them to better contact the solvent and anions in the electrolyte, thus effectively anchoring the electrolyte. Fluorinated alkyl groups can influence the distribution of solvent and anions in the electrolyte through electrostatic interactions and steric hindrance, thereby achieving an anchoring effect. Chain alkoxy groups (such as methoxy-O-CH3, ethoxy-O-CH2-CH3, etc.) have oxygen atoms and alkyl structures. The oxygen atoms can form hydrogen bonds with solvent molecules in the electrolyte or generate electrostatic interactions with cations, while the alkyl groups can adjust the steric hindrance of the groups, thereby stabilizing the solvent and anions in the electrolyte.

[0116] In some embodiments, the molar ratio of the first structural unit to the second structural unit is 2:(3-5). Exemplary examples show that the molar ratio of the first structural unit to the second structural unit can be typical but non-limiting values ​​such as 2:3, 2:4, and 2:5.

[0117] Within this ratio range, the first structural unit and the second structural unit can be interconnected to form a polymer matrix with a three-dimensional network structure.

[0118] In some embodiments, the polymer matrix comprises at least one of the polymers shown in Formula III-1 to Formula III-4:

[0119]

[0120]

[0121] Where k is a natural number greater than or equal to 10; R is a C1-C20 alkyl group.

[0122] For example, k is a natural number between 10 and 1,000,000.

[0123] From a spatial perspective, these polymers extend in multiple directions, indicating a three-dimensional network structure. On one hand, this network contains abundant, interconnected channels, providing continuous and stable pathways for ion transport. Ions can migrate smoothly within these channels, reducing energy loss and migration resistance caused by interruptions or blockages in the transport path, thus increasing the ion migration rate. On the other hand, ions can also migrate along the surface or interior of the polymer material constituting the three-dimensional network. This multi-dimensional migration mechanism effectively promotes the ion migration rate in the gel electrolyte, endowing it with good ionic conductivity.

[0124] Meanwhile, these polymers have high chemical stability, good adhesion and flexibility, and excellent mechanical properties. Therefore, when these polymers are applied to the gel electrolyte system, the gel electrolyte can form a tight and stable bonding interface with the negative electrode, thereby effectively improving the safety and reliability of the battery during use.

[0125] In some embodiments, the content of the polymer matrix is ​​0.5%-30% based on the total weight of the gel electrolyte. Exemplarily, the content of the polymer matrix can be typical but not limiting values ​​such as 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%.

[0126] An appropriate amount of polymer matrix endows gel electrolytes with good mechanical strength and high electrochemical stability. At the same time, it can form an effective three-dimensional network structure in the gel electrolyte, which can guide the migration path of ions, making ion conduction more orderly and thus forming a good ion transport channel.

[0127] In some embodiments, the electrolyte comprises a solvent and a lithium salt, wherein the solvent comprises an ether solvent.

[0128] Because the second structural unit contains ether oxygen segments, the polymer matrix formed by its polymerization also contains ether oxygen segments. Furthermore, the electrolyte also contains ether solvents. This results in a high affinity between the polymer matrix and the ether electrolyte at the molecular level. This facilitates the interweaving of the ether oxygen segments in the polymer matrix with the solvent molecules in the electrolyte, forming a stable mixed structure. This structure effectively binds the electrolyte within the polymer matrix of the gel system, thus preventing free flow of the electrolyte. In particular, the ether bonds in the ether solvent can interact with the anchoring structures in the polymer matrix, further promoting the effective binding of the electrolyte within the three-dimensional framework structure formed by the polymer matrix. Simultaneously, this mutually dissolved and mixed state also facilitates ion migration within the gel electrolyte, endowing it with high ionic conductivity.

[0129] In some embodiments, the anchoring structure in the polymer matrix is ​​bonded to the solvent and anions in the electrolyte through at least one chemical bond selected from hydrogen bonds and coordination bonds.

[0130] These chemical bonds enable the construction of a more robust polymer matrix-electrolyte bonding system, resulting in a more stable gel electrolyte. Hydrogen bonds provide a relatively wide range of bonding sites, while coordination bonds offer strong interactions at key ion binding sites. This combination allows the polymer matrix to bind the electrolyte at multiple levels and angles, effectively mitigating electrolyte evaporation and accumulation during cycling and reducing the uncontrollable risks associated with the battery.

[0131] In some embodiments, the solvent includes a main solvent and a diluent, wherein the main solvent includes at least one of chain ether solvents and cyclic ether solvents.

[0132] For example, chain ether solvents include, but are not limited to, at least one of the following: trimethyl phosphate, triethyl phosphate, tributyl phosphate, fluoroethylene carbonate, diethyl ether, dipropyl ether, ethylpropyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol diethyl ether, butanediol dimethyl ether, butanediol diethyl ether, butanediol diethyl ether, and butanediol diethyl ether.

[0133] For example, cyclic ether solvents include, but are not limited to, at least one of tetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane.

[0134] In some embodiments, the diluent includes at least one of aromatic solvents, fluoroalkane solvents, and fluoroether solvents.

[0135] For example, aromatic solvents include, but are not limited to, at least one of benzene, fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluorotoluene, trifluoromethoxybenzene, and decafluoropentane.

[0136] For example, fluoroalkane solvents include, but are not limited to, at least one of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(difluoromethoxy)ethane, 1,2-bis(trifluoromethoxy)ethane, 1,2-diethoxy-1,1,2,2-tetrafluoroethane, and 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane.

[0137] For example, fluorinated ether solvents include, but are not limited to, bis(2,2,2-trifluoroethyl) ether, bis(2,2-difluoroethyl) ether, 1,1,2,3,3,3-hexafluoropropylethyl ether, 1H,1H,5H - Octafluoropentyl - 1,1,2,2 - Tetrafluoroethyl ether, ethyl trifluoromethyl ether, difluoromethyl-2,2,3,3,3 - Pentafluoropropyl ether, heptafluoropropyl-1,2,2,2 - At least one of the following: tetrafluoroethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, perfluoroisopropylmethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, ethyl-2,2,2-tetrafluoroethyl ether, and bis(1,1,2,2-tetrafluoroethyl) ether.

[0138] By forming a locally high-concentration electrolyte through the main solvent and diluent, an inorganic-rich SEI film can be formed on the negative electrode surface. This SEI film has good mechanical and chemical stability, which can effectively prevent further reactions between the electrode and the electrolyte, inhibit the growth of lithium dendrites, and thus improve the cycle life and safety of the battery.

[0139] In some embodiments, based on the total weight of the solvents, the content of the main solvent is 10%-80%, and the content of the diluent is 20%-90%. Exemplarily, the content of the main solvent can be typical but not limiting values ​​such as 10%, 20%, 30%, 40%, 50%, 60%, 70%, and 80%. The content of the diluent can be typical but not limiting values ​​such as 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90%.

[0140] The main solvent effectively dissolves lithium salts, facilitating their complete dissociation and generating more solvated lithium ions, thereby improving the ionic conductivity of the electrolyte. The diluent optimizes the electrolyte viscosity, allowing for smoother lithium ion transport and enhancing the battery's electrochemical performance. Therefore, controlling the content of the main solvent and diluent within the aforementioned ranges can adjust the solvation structure in the electrolyte, thereby improving the electrolyte's ionic conductivity and the battery's cycle performance.

[0141] In some embodiments, the molar concentration of the lithium salt in the electrolyte is 0.5 mol / L to 6 mol / L. Exemplarily, the molar concentration of the lithium salt can be typical but not limiting values ​​such as 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, and 6 mol / L.

[0142] Within this range, the electrolyte exhibits good ionic conductivity, which helps increase the number of freely mobile solvated ions, thereby improving the battery's charge and discharge efficiency.

[0143] In some embodiments, the electrode assembly includes a negative electrode sheet, the negative electrode sheet includes a negative electrode material, and the negative electrode material includes any one of elemental lithium and lithium alloy.

[0144] Lithium metal anodes possess extremely low electrode potential (-3.04V vs. standard hydrogen electrode) and high specific capacity (up to 3860mAh / g), making them one of the ideal anodes for next-generation high-energy-density batteries. However, lithium metal anodes still face a series of technical challenges that urgently need to be overcome. First, lithium metal anodes have high chemical reactivity. Therefore, during secondary battery cycling, lithium metal continuously reacts with the electrolyte, constantly consuming active lithium. This continuous consumption of active lithium leads to irreversible loss of battery capacity, directly reducing battery cycle life and affecting long-term battery performance. Second, lithium metal anodes have poor interfacial stability. This instability can cause localized heat generation. Once heat accumulates, causing the cell to reach its self-heating temperature T1 prematurely, it can easily trigger the self-heating process, potentially leading to thermal runaway and seriously threatening battery safety. Third, after cycling, lithium metal anode cells are prone to lithium pulverization in the tab and overhang areas. Lithium pulverization increases the battery's internal resistance, further affecting battery performance, and may also cause internal short circuits, leading to safety accidents.

[0145] Therefore, the electrolyte, constructed from the first and second structural units into a gel system, contains a three-dimensional framework structure composed of a polymer matrix. The electrolyte is bound within this three-dimensional framework through an anchoring structure. This effectively mitigates the volatility of the electrolyte during battery cycling, reducing the amount of electrolyte volatilization and thus preventing abnormal electrolyte distribution caused by re-accumulation after volatilization. This, in turn, helps improve the relative stability of the internal electrochemical environment of the battery. Simultaneously, because the electrolyte does not easily move and diffuse freely, it is less likely to diffuse to the tabs or overhang regions, and even less likely to accumulate in large quantities in these regions. This effectively suppresses the formation of lithium dendrites and lithium powder, reducing the risk of internal short circuits and thermal runaway, thereby significantly improving battery reliability. Furthermore, the gel electrolyte can form a tight and stable interface with the negative electrode. This stable interface reduces defects and micro-gaps at the interface, making the transport of lithium ions at the interface more uniform and orderly, thereby improving the stability of the entire negative electrode-gel electrolyte interface. Due to the improved interface stability, the local heat generation caused by charge accumulation and uneven reaction at the interface is reduced, reducing the early heat generation sources and the rate of heat accumulation. Under the same charge and discharge conditions, the battery can withstand higher temperatures without entering the self-heating state, that is, delaying the occurrence of self-heating. This delay gives the battery a larger temperature safety margin during normal operation, that is, the self-heating temperature is increased, thereby improving the safety and reliability of the battery during use.

[0146] In one embodiment, the negative electrode sheet includes a negative current collector and a negative electrode material, the negative electrode material being disposed on at least one side of the negative current collector, and the negative electrode material including any one of pure lithium and lithium alloy. In another embodiment, the negative electrode sheet can be a metal sheet, such as a sheet formed of pure lithium or a pure lithium alloy.

[0147] For example, the negative electrode material can be disposed on one side of the negative electrode current collector or on both sides of the negative electrode current collector.

[0148] For example, the negative electrode current collector can be a metal foil or a composite current collector. The metal foil can be copper foil. The composite current collector can be a polymer matrix material and a metal layer formed on at least one surface of the polymer matrix material. The composite current collector can be formed on the surface of the polymer matrix material using copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, or silver alloys. The polymer matrix material can be polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.

[0149] For example, the lithium alloy may include lithium and at least one metallic element selected from aluminum (Al), magnesium (Mg), potassium (K), sodium (Na), calcium (Ca), strontium (Sr), barium (Ba), germanium (Ge), antimony (Sb), lead (Pb), indium (In), zinc (Zn), tin (Sn), silver (Ag), and gold (Au).

[0150] For example, a lithium alloy may include lithium and a lithium alloy composed of at least one quasi-metallic element selected from boron (B), carbon (C), and silicon (Si).

[0151] In some embodiments, the electrode assembly in a single battery cell includes a negative electrode, a positive electrode, and a separator disposed between the positive and negative electrodes. During battery charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The separator, disposed between the positive and negative electrodes, primarily serves to prevent short circuits between the positive and negative electrodes while allowing ions to pass through.

[0152] [Positive electrode plate]

[0153] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The aforementioned "positive electrode film layer disposed on at least one surface of the positive current collector" means that the positive electrode film layer can be disposed on one surface of the positive current collector along its own thickness direction, or it can be disposed on two surfaces of the positive current collector along its own thickness direction.

[0154] This application does not impose any particular limitation on the positive electrode current collector, as long as it can achieve the purpose of this application. In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0155] In some embodiments, the positive electrode film contains a positive electrode active material, which may include positive electrode active materials known in the art for use in batteries. As an example, the positive electrode active material of a lithium-ion battery cell may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, at least one of lithium cobalt oxide, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, nickel-cobalt-manganese-aluminum quaternary materials, lithium iron phosphate, lithium manganese phosphate, lithium vanadium phosphate, lithium manganese oxide, and their modified compounds. Examples of lithium-containing phosphates with an olivine structure include, but are not limited to, at least one of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. The weight ratio of the positive electrode active material in the positive electrode active layer is 80wt%-100wt%, based on the total weight of the positive electrode active layer.

[0156] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder in the positive electrode film layer may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a terpolymer of PVDF-tetrafluoroethylene-propylene, a terpolymer of PVDF-hexafluoropropylene-tetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorinated acrylate resin. The binder accounts for 0-20 wt% of the positive electrode film layer based on the total weight of the positive electrode active layer.

[0157] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, carbon black (e.g., acetylene black or Ketjen black), carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The conductive agent comprises 0-20 wt% of the positive electrode film, based on the total weight of the positive electrode film.

[0158] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g. N-methylpyrrolidone) to form a positive electrode slurry, coating the positive electrode slurry on the surface of the positive current collector, drying it and then cold pressing it through a cold rolling mill to form the positive electrode sheet.

[0159] [Isolation membrane]

[0160] The separator is used to separate the positive electrode and the negative electrode, prevent short circuits inside the battery cell, allow electrolyte ions to pass freely, and does not affect the electrochemical charging and discharging process.

[0161] This application does not impose any particular restrictions on the separator membrane; as long as it can achieve the purpose of this application, any well-known porous separator membrane with good chemical and mechanical stability can be selected.

[0162] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0163] In some embodiments, the positive electrode, negative electrode, and separator described above can be fabricated into an electrode assembly by a winding process or a stacking process.

[0164] In some embodiments, a single battery cell may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and gel electrolyte described above.

[0165] The second aspect of this application provides a method for preparing a battery cell, comprising the following steps:

[0166] Step S10: Add the first monomer and the second monomer to the electrolyte to obtain the gel electrolyte precursor solution;

[0167] Step S20: Inject the gel electrolyte precursor solution into the electrode assembly, and then carry out a polymerization reaction to form a gel electrolyte from the gel electrolyte precursor solution, thereby obtaining a battery cell.

[0168] The structural formula of the first monomer is shown in formula (IV), and the structural formula of the second monomer is shown in formula (V).

[0169]

[0170] Wherein, R1, R2, R3, R4, and R5 independently include any one of vinyl, hydroxyl, amino, mercapto, isocyanate, and acrylate groups; at least one group among R1, R2, R3, R4, and R5 contains a double bond; at least one group among R4 and R5 can undergo a condensation reaction with at least one group among R1, R2, and R3; M1, M2, M3, M4, M5, and M6 independently include an anchoring structure; n is any natural number from 2 to 2000, and m is any natural number from 20 to 2000.

[0171] The method for preparing a battery cell provided in this application involves first adding a first monomer and a second monomer to an electrolyte, and then injecting the resulting precursor solution into an electrode assembly. Through heat treatment, the first monomer and the second monomer undergo a relatively thorough in-situ polymerization and solidification reaction to form a gel electrolyte, thereby effectively preparing a battery cell with the performance described above.

[0172] In some embodiments, in step S10, at least one of the groups R1, R2, and R3 in the first monomer is an isocyanate group, and at least one of the groups R4 and R5 in the second monomer is selected from either hydroxyl or amino groups.

[0173] The isocyanate group (-NCO) is a relatively reactive functional group that can undergo condensation polymerization with hydroxyl groups (-OH) to form a polyurethane structure (-NH-CO-O-) and with amino groups (-NH2) to form a polyurea structure (-NH-CO-NH-). The resulting structures have dynamic hydrogen bond structures, which is beneficial for forming a flexible and self-healing three-dimensional polymer network structure. Moreover, the polymer matrix containing the polyurea structure has good positive and negative electrode stability and structural strength, which helps to improve the mechanical properties and electrochemical stability of the gel electrolyte during cycling.

[0174] When the isocyanate group of the first monomer reacts with the hydroxyl or amino group of the second monomer, linear polymer chains are formed. As the reaction proceeds, these polymer chains grow and cross-link with each other. Due to the interactions between multiple monomers, a three-dimensional network structure is eventually formed, which is the three-dimensional framework of the gel system.

[0175] In some embodiments, in step S10, at least one of the groups R1, R2, and R3 in the first monomer is vinyl, and at least one of the groups R4 and R5 in the second monomer is selected from any one of mercapto, vinyl, and acrylate groups.

[0176] Vinyl groups (-CH=CH2) contain unsaturated carbon-carbon double bonds, which can react with thiol groups (-SH), vinyl groups (-CH=CH2), and acrylate groups (-COO-CH=CH2). For example, vinyl groups react with thiol groups to form thioether bonds; two vinyl groups react to form a polymer linked by carbon-carbon bonds; vinyl groups react with acrylate groups to form carbon-carbon single bonds. Thus, the vinyl groups in the first monomer can react with thiol groups, vinyl groups, or acrylate groups in the second monomer to form a polymer matrix with a three-dimensional network structure.

[0177] In some embodiments, in step S10, at least one of the groups R1, R2, and R3 in the first monomer is an acrylate group, and at least one of the groups R4 and R5 in the second monomer is selected from either vinyl or acrylate groups.

[0178] Both acrylate groups (-COO-CH=CH2) and vinyl groups (-CH=CH2) are active functional groups capable of polymerization. Addition polymerization primarily occurs between acrylate groups (-COO-CH=CH2) and vinyl groups (-CH=CH2), resulting in a polymer matrix containing ester bonds (-COO-) and carbon-carbon single bonds (-CC-). Addition polymerization also primarily occurs between acrylate groups, with multiple structural units linked by carbon-carbon single bonds. Therefore, a first monomer containing acrylate groups and a second monomer containing vinyl and acrylate groups can react to form a polymer matrix.

[0179] In some embodiments, in step S10, the molar ratio of the first structural unit to the second structural unit is 2:(3-5).

[0180] Within this ratio range, the end groups of the first monomer and the second monomer can basically match and react completely, so there is less chance of monomer residue. This makes it less likely to interfere with the electrode-gel electrolyte interface of the battery, and the interface layer is less likely to have unevenness problems, which helps to improve the cycle performance and life of the battery. At the same time, it can also reduce the problem of irreversible side reactions of residual monomers on the electrode surface, thereby reducing the consumption of active lithium, which is beneficial to improving the coulombic efficiency of the battery.

[0181] In some embodiments, in step S10, the anchoring structure includes at least one of hydrogen atom, halogen atom, hydroxyl group, amino group, hydroxyl or amino-substituted C1-C5 chain alkyl group, fluorinated chain alkyl group and chain alkoxy group.

[0182] These anchoring structures can interact with solvent molecules and anions in the electrolyte, which allows the electrolyte to be firmly bound within the three-dimensional framework of the gel system.

[0183] In some embodiments, in step S20, the positive electrode, negative electrode, and separator included in the electrode assembly are as described above, and will not be repeated here.

[0184] The preparation method of the electrode assembly is as described above and will not be repeated here.

[0185] In some embodiments, step S20 further includes a settling treatment before the polymerization reaction, wherein the settling conditions include settling at 15°C-30°C for 2-12 hours.

[0186] During the settling process, the gel electrolyte precursor solution can fully wet the electrode components, making the distribution of the gel electrolyte precursor solution more uniform throughout the battery system.

[0187] In some embodiments, in step S20, the conditions for the polymerization reaction include heat treatment at 40°C-80°C for 10-24 hours. Exemplarily, the heat treatment temperature can be typical but not limiting values ​​such as 40°C, 50°C, 60°C, 70°C, 80°C, etc. The heat treatment time can be typical but not limiting values ​​such as 10 hours, 12 hours, 14 hours, 16 hours, 20 hours, 24 hours, etc.

[0188] Under these conditions, the active functional groups of the first and second monomers react to form a polymer matrix with a three-dimensional network structure.

[0189] A third aspect of this application provides a battery device comprising a plurality of battery cells described in the above embodiments.

[0190] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0191] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0192] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0193] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cell assemblies housed within the housing.

[0194] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0195] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0196] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0197] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0198] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0199] A fourth aspect of this application provides an electrical device, including a battery cell or a battery device as described in the above embodiments, wherein the battery cell or battery device is used to store or provide electrical energy.

[0200] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0201] The following description, with appropriate reference to the accompanying drawings, describes the battery cell, battery device, and power consumption device provided in the embodiments of this application.

[0202] Figure 1 This is an exploded view of a battery device 100 as an example. The battery device 100 includes a housing 10 and battery cell assemblies 20, with the battery cell assemblies 20 housed within the housing 10. The housing 10 provides a space for housing the battery cell assemblies 20 and can have various structures. In some embodiments, the housing 10 may include a first housing 11 and a second housing 12, which overlap each other, collectively defining a closed space for housing the battery cell assemblies 20. Of course, the housing 10 formed by the first housing 11 and the second housing 12 can have various shapes, such as a cylinder, a cuboid, etc. Multiple battery cell assemblies 20 can be arranged in any manner within the battery housing.

[0203] In the battery device 100, there can be one or more battery cell components 20. Multiple battery cell components 20 can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cell components 20 are connected in both series and parallel. Multiple battery cell components 20 can be directly connected in series, parallel, or in a mixed manner, and then the whole formed by multiple battery cell components 20 is housed in the housing 10. Of course, the battery device 100 can also be formed by first connecting multiple battery cell components 20 in series, parallel, or in a mixed manner to form a battery module, such as a battery module or battery pack. Multiple battery modules are then connected in series, parallel, or in a mixed manner to form a whole and housed in the housing 10.

[0204] Battery cell assembly 20 includes multiple battery cells 30. Figure 2 This is an exploded view of a single battery cell 30 as an example. The single battery cell 30 includes a housing 31, a cover plate 33, an electrode assembly 32, and other functional components.

[0205] The housing 31 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 31 is a hollow structure with an opening at one end, and the housing 31 is used to cooperate with the cover plate 33 to form an internal environment for accommodating the electrode assembly 32, electrolyte, and other functional components. The housing 31 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 31 can be determined according to the specific shape and size of the electrode assembly 32. The material of the housing 31 can be, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and is not limited here. The cover plate 33 is a component that covers the opening of the housing 31 to isolate the internal environment of the battery cell 30 from the external environment. The material of the cover plate 33 can be, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and is not limited here.

[0206] Figure 3 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0207] The fifth aspect of this application provides a gel electrolyte, including a polymer matrix and an electrolyte, wherein the polymer matrix includes a first structural unit and a second structural unit, the first structural unit having the structural formula shown in formula (I), and the second structural unit having the structural formula shown in formula (II).

[0208]

[0209] The first structural unit and the second structural unit are connected by at least one chemical bond selected from urethane bonds, urea bonds, carbon-sulfur single bonds, carbon-carbon single bonds, and ester bonds.

[0210] Where * represents a connection point; M1, M2, M3, M4, M5, and M6 each independently include an anchoring structure; n is any natural number from 2 to 2000, and m is any natural number from 20 to 2000.

[0211] The gel electrolyte provided in this application comprises a first structural unit and a second structural unit that can construct a gel system electrolyte. Internally, it contains a three-dimensional framework structure composed of a polymer matrix. Since both the first and second structural units contain benzene ring structures, the rigidity of the benzene rings mechanically inhibits the growth of lithium dendrites and withstands their penetration, giving the gel electrolyte high structural stability and mechanical strength. This reduces the problem of internal short circuits caused by lithium dendrite growth, thereby improving battery reliability. The linear components, such as ether oxygen segments, in the second structural unit endow the gel electrolyte with high flexibility. This flexibility allows the gel electrolyte to adapt well to volume changes in the negative electrode material caused by the insertion and extraction of active ions, thus helping to maintain relatively close contact between the gel electrolyte and the negative electrode sheet. This allows for smooth lithium ion transport between the negative electrode and the gel electrolyte. Furthermore, the flexible gel electrolyte can form a flexible interface with the negative electrode sheet. When the volume of the negative electrode material changes, the gel electrolyte can buffer the stress caused by this change through flexible deformation, making the SEI film less prone to breakage and improving its stability. This reduces the consumption of active lithium, lowers the battery's internal resistance, and improves the battery's cycle life and safety.

[0212] In some embodiments, the anchoring structure described above includes at least one of a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a substituted alkyl group, and a chain alkoxy group, wherein the substituent in the substituted alkyl group includes a hydroxyl group, an amino group, or a halogen atom.

[0213] These anchoring structures can interact with solvent molecules and anions in the electrolyte, which allows the electrolyte to be firmly bound within the three-dimensional framework of the gel system.

[0214] In some embodiments, the electrolyte comprises a solvent and a lithium salt, wherein the solvent includes ether solvents.

[0215] The ether bonds in ether solvents can interact with the anchoring structures in the polymer matrix, thereby effectively binding the electrolyte within the three-dimensional framework structure formed by the polymer matrix.

[0216] In some embodiments, the solvent includes a main solvent and a diluent, wherein the main solvent includes at least one of chain ether solvents and cyclic ether solvents.

[0217] In some embodiments, the diluent includes at least one of aromatic solvents, fluoroalkane solvents, and fluoroether solvents.

[0218] By using these main solvents and diluents to form a locally high-concentration electrolyte, an inorganic-rich SEI film can be formed on the negative electrode surface. This SEI film has good mechanical and chemical stability, which can effectively prevent further reactions between the electrode and the electrolyte, inhibit the growth of lithium dendrites, and thus improve the cycle life and safety of the battery.

[0219] Because the polymer matrix contains ether oxygen segments and the main solvent contains ether solvents, the two have similar structures. This similar chemical structure enables the polymer matrix and electrolyte in the gel system to have affinity at the molecular level. This means that the gel system composed of the polymer matrix has high compatibility and good interaction with the locally high-concentration electrolyte, which helps to improve the interfacial compatibility between the polymer matrix and the electrolyte. This makes it easier for the electrolyte to be bound in the three-dimensional framework and optimizes the ion transport channels in the gel electrolyte, giving the gel electrolyte a high ion conductivity.

[0220] In some embodiments, the gel electrolyte can be prepared using the following methods:

[0221] The first monomer and the second monomer are added to the electrolyte, and heat treatment is performed to cause the first monomer and the second monomer to undergo a polymerization reaction to form a gel electrolyte.

[0222] Example

[0223] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0224] Example 1

[0225] This embodiment provides a gel electrolyte and a battery cell.

[0226] Gel electrolyte

[0227] Electrolyte

[0228] Take 1.2 mol of the main solvent (ethylene glycol dimethyl ether) and 3 mol of the diluent (1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether), mix them together, and then add 1 mol of lithium salt (lithium bisfluorosulfonylimide) to the mixed solvent to obtain the electrolyte.

[0229] [Gel Electrolyte Precursor Solution]

[0230] The first monomer, as shown in Formula IV-1, and the second monomer, as shown in Formula V-1, are added to the electrolyte at a molar ratio of 2:3 to obtain a gel electrolyte precursor solution. The mass content of the polymerizable monomers (including the first monomer and the second monomer) in the gel electrolyte precursor solution is 20%.

[0231]

[0232] [Gel Electrolyte]

[0233] The gel electrolyte precursor solution was heat-treated at 60°C for 12 hours to form a gel electrolyte.

[0234] battery cell

[0235] [Positive electrode plate]

[0236] Lithium nickel cobalt manganese oxide (Ni80), conductive agent acetylene black, and binder PVDF were mixed at a mass ratio of 98:1:1. NMP solvent was added and stirred until the system was homogeneous to obtain the positive electrode slurry. The positive electrode slurry was uniformly coated on both sides of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. It was then cut into 40mm × 50mm rectangles to serve as the positive electrode sheet, with an areal capacity of 3.367 mAh / cm². 2 .

[0237] [Negative electrode plate]

[0238] A 50μm thick lithium foil is coated onto a 13μm thick copper foil using a rolling process, and then cut into 41mm×51mm rectangles to serve as the negative electrode.

[0239] [Isolation membrane]

[0240] The polyethylene used as the separator has a thickness of 13 μm.

[0241] [Assembly of individual battery cells]

[0242] Ten pre-cut positive electrode sheets and eleven pre-cut negative electrode sheets were matched together, with a separator film placed between the positive and negative electrode sheets. Then, a Z-shaped stacking assembly was performed. Finally, the resulting electrode assembly was wrapped in an aluminum-plastic film bag to form a stacked dry cell. 3.0g of the gel electrolyte precursor solution prepared in Example 1 was injected into the dry cell, and the aluminum-plastic film bag was then vacuum-sealed. After standing at room temperature for 6 hours, it was heat-treated at 60°C for 12 hours to allow the first and second monomers to polymerize and solidify in situ to form a gel electrolyte, thus preparing a stacked battery cell with a rated capacity of 1.4Ah.

[0243] Example 2

[0244] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the second monomer is different, and the mass content of the polymerized monomer in the gel electrolyte precursor solution is 16%.

[0245] The structural formulas of the first and second monomers are as follows:

[0246]

[0247] Example 3

[0248] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the second monomer is different, and the mass content of the polymerized monomer in the gel electrolyte precursor solution is 25%.

[0249] The structural formulas of the first and second monomers are as follows:

[0250]

[0251] Example 4

[0252] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the second monomer is different, and the mass content of the polymerized monomer in the gel electrolyte precursor solution is 27%.

[0253] The structural formulas of the first and second monomers are as follows:

[0254]

[0255] Example 5

[0256] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the second cell is different.

[0257] The structural formulas of the first and second monomers are as follows:

[0258]

[0259] Example 6

[0260] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the second monomer is different, and the mass content of the polymerized monomer in the gel electrolyte precursor solution is 24%.

[0261] The structural formulas of the first and second monomers are as follows:

[0262]

[0263] Example 7

[0264] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the second monomer is different, and the mass content of the polymerized monomer in the gel electrolyte precursor solution is 28%.

[0265] The structural formulas of the first and second monomers are as follows:

[0266]

[0267] Example 8

[0268] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the second cell is different.

[0269] The structural formulas of the first and second monomers are as follows:

[0270]

[0271] Example 9

[0272] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the molar ratio of the first cell to the second cell is 2:5.

[0273] Example 10

[0274] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the second cell is different.

[0275] The structural formulas of the first and second monomers are as follows:

[0276]

[0277] Example 11

[0278] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the second cell is different.

[0279] The structural formulas of the first and second monomers are as follows:

[0280]

[0281] Example 12

[0282] This embodiment provides a gel electrolyte and a battery cell, which differ from Embodiment 1 in that the gel electrolyte is different, specifically the first cell and the second cell are different.

[0283] The structural formulas of the first and second monomers are as follows:

[0284]

[0285]

[0286] Example 13

[0287] This embodiment provides a gel electrolyte and a battery cell, which differ from Embodiment 1 in that the gel electrolyte is different, specifically the first cell and the second cell are different.

[0288] The structural formulas of the first and second monomers are as follows:

[0289]

[0290] Example 14

[0291] This embodiment provides a gel electrolyte and a battery cell, which differ from Embodiment 1 in that the gel electrolyte is different, specifically the first cell and the second cell are different.

[0292] The structural formulas of the first and second monomers are as follows:

[0293]

[0294] Example 15

[0295] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the second cell is different.

[0296] The structural formulas of the first and second monomers are as follows:

[0297]

[0298] Example 16

[0299] This embodiment provides a gel electrolyte and a battery cell, which differs from Embodiment 1 in that the gel electrolyte is different, specifically the electrolyte solution is different:

[0300] 1.2 mol of the main solvent (trimethyl phosphate) and 3 mol of the diluent (1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether) were mixed, and then 1 mol of lithium salt (lithium hexafluorophosphate) was added to the mixed solvent to obtain the electrolyte.

[0301] Comparative Example 1

[0302] This comparative example provides a gel electrolyte and a battery cell, which differs from Example 1 in that: no gel electrolyte is formed, specifically: no polymer matrix is ​​present.

[0303] Ten pre-cut positive electrode sheets and eleven pre-cut negative electrode sheets were matched together, with a separator film placed between the positive and negative electrode sheets. Then, a Z-shaped stacking assembly was performed. Finally, the resulting electrode assembly was wrapped in an aluminum-plastic film bag to form a stacked dry cell. 3.0g of the electrolyte prepared in Example 1 was injected into the dry cell, and the aluminum-plastic film bag was then vacuum-sealed. After standing at room temperature for 6 hours, a stacked battery cell with a rated capacity of 1.4Ah was obtained.

[0304] Comparative Example 2

[0305] This comparative example provides a gel electrolyte and a battery cell, which differ from Example 1 in that the gel electrolyte is different, specifically the electrolyte solution is different.

[0306] 1 mol of lithium salt (lithium hexafluorophosphate) was added to 4.2 mol of solvent (ethylene carbonate) to obtain the electrolyte.

[0307] Comparative Example 3

[0308] This comparative example provides a gel electrolyte and a battery cell, which differs from Example 1 in that the gel electrolyte is different, specifically, no gel electrolyte is formed.

[0309] [Gel Electrolyte Precursor Solution]

[0310] The second monomer, as shown in Formula II-1, is added to the electrolyte to obtain a gel electrolyte precursor solution, wherein the mass content of the polymerized monomer (second monomer) in the gel electrolyte precursor solution is 20%.

[0311] Comparative Example 4

[0312] This comparative example provides a gel electrolyte and a battery cell, which differ from Example 1 in that the gel electrolyte is different, specifically: the polymer monomer only includes acrylate monomers.

[0313] Performance testing

[0314] (1) Testing of self-generated heat temperature T1 and thermal runaway temperature T2

[0315] Accelerated rate calorimetry (ARC) was used to test the self-generated heat temperature T1 and thermal runaway temperature T2 of the battery cells during the heating process.

[0316] The ARC test procedure and temperature settings are shown in Table 1 below.

[0317] Table 1

[0318]

[0319]

[0320] In Table 1, Temp Step refers to the time required to maintain the temperature for 40 minutes after each 3°C increase.

[0321] T1: dT / dt ≥ 0.02℃ / min;

[0322] T2: dT / dt ≥ 60℃ / min;

[0323] HWS (Heat-Wait-Seak): This refers to the research method used in the heating phase before T1, which involves heating to a specified temperature, waiting, and then entering an adiabatic environment. The heat dissipation rate of the battery is monitored; if it reaches 0.02℃ / min, heating is stopped, and an adiabatic follow-up phase begins, where the ambient temperature remains consistent with the battery temperature to prevent any heat exchange until thermal runaway is reached. After reaching T3, the cavity is breached, and the cooling phase begins.

[0324] (2) Reliability

[0325] After cycling the battery cells prepared in Examples 1-16 and Comparative Examples 1-4 for 120 cycles according to the following steps, the battery cells were disassembled, and it was observed whether lithium powder was generated at the tabs or overhangs.

[0326] Using human visual observation, if no lithium pulverization is generated in the observation area (≥95%), including the tab and overhang areas, it is considered to be either present or absent.

[0327] Cycling process: The prepared battery cell is charged at a constant current rate of 0.2C, then charged at a constant voltage of 4.3V to 0.1C; then discharged at a rate of 1C, with the voltage range controlled between 2.8-4.3V, and so on, to perform charge and discharge cycles.

[0328] The test results are listed in Table 2 below.

[0329] Table 2

[0330]

[0331]

[0332] As can be clearly seen from Table 2, the electrolyte of the gel system can be constructed through the polymerization reaction of the first and second monomers, and the electrolyte is bound in the three-dimensional skeleton of the gel system. This not only effectively inhibits the formation of lithium dendrites and lithium pulverization, reducing the risk of internal short circuits and thermal runaway, but also increases the self-heating temperature of the battery, thereby significantly improving the safety and reliability of the battery during use.

[0333] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized by, The device includes an electrode assembly and a gel electrolyte. The gel electrolyte includes a polymer matrix and an electrolyte solution. The polymer matrix includes a first structural unit and a second structural unit. The first structural unit has the structural formula shown in formula (I), and the second structural unit has the structural formula shown in formula (II). The first structural unit and the second structural unit are connected by at least one chemical bond selected from urethane bonds, urea bonds, carbon-sulfur single bonds, carbon-carbon single bonds, and ester bonds; Where * represents a connection point; M1, M2, M3, M4, M5, and M6 each independently include an anchoring structure; n is any natural number from 2 to 2000, and m is any natural number from 20 to 2000.

2. The battery cell of claim 1, wherein, The n is any natural number from 2 to 10; and / or The value of m is any natural number between 90 and 120.

3. The battery cell of any one of claims 1 to 2, wherein, The anchoring structure includes at least one of hydrogen atom, halogen atom, hydroxyl group, amino group, substituted alkyl group and alkoxy group, wherein the substituent in the substituted alkyl group includes hydroxyl group, amino group or halogen atom.

4. The battery cell of any one of claims 1 to 3, wherein, The molar ratio of the first structural unit to the second structural unit is 2:(3-5).

5. The battery cell of any one of claims 1 to 4, wherein, The polymer matrix includes at least one of the polymers shown in Formula III-1 to Formula III-4: Where k is a natural number greater than or equal to 10, and R is a C1-C20 alkyl group.

6. The battery cell of any one of claims 1 to 5, wherein, The content of the polymer matrix is ​​0.5%-30% based on the total weight of the gel electrolyte.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The electrolyte includes a solvent and a lithium salt, and the solvent includes ether solvents.

8. The battery cell as described in claim 7, characterized in that, The anchoring structure in the polymer matrix is ​​bonded to the solvent and anions in the electrolyte through at least one chemical bond, namely hydrogen bond or coordination bond.

9. The battery cell as described in claim 7 or 8, characterized in that, The solvent includes a main solvent and a diluent, wherein the main solvent includes at least one of chain ether solvents and cyclic ether solvents; and / or, The diluent includes at least one of aromatic solvents, fluoroalkane solvents, and fluoroether solvents.

10. The battery cell as described in claim 9, characterized in that, Based on the total weight of the solvents, the content of the main solvent is 10%-80%, and the content of the diluent is 20%-90%.

11. The battery cell according to any one of claims 7 to 10, characterized in that, The molar concentration of the lithium salt in the electrolyte is 0.5 mol / L to 6 mol / L.

12. The battery cell according to any one of claims 1 to 11, characterized in that, The electrode assembly includes a negative electrode sheet, the negative electrode sheet includes a negative electrode material, and the negative electrode material includes any one of elemental lithium and lithium alloy.

13. A method for preparing a single battery cell, characterized in that, Includes the following steps: The first and second monomers are added to the electrolyte to obtain the gel electrolyte precursor solution; The gel electrolyte precursor solution is injected into the electrode assembly, and then a polymerization reaction is carried out to form a gel electrolyte, thereby obtaining a battery cell. The first monomer has the structural formula shown in formula (IV), and the second monomer has the structural formula shown in formula (V). R1, R2, R3, R4, and R5 each independently include any one of vinyl, hydroxyl, amino, mercapto, isocyanate, or acrylate groups; at least one group in R1, R2, and R3 contains a double bond; at least one group in R4 and R5 can undergo a condensation reaction with at least one group in R1, R2, and R3; M1, M2, M3, M4, M5, and M6 each independently include an anchoring structure. n is any natural number from 2 to 2000, and m is any natural number from 20 to 2000.

14. The method for preparing a single battery cell as described in claim 13, characterized in that, In the first monomer, at least one of R1, R2, and R3 is an isocyanate group, and in the second monomer, at least one of R4 and R5 is selected from either hydroxyl or amino groups.

15. The method for preparing a single battery cell as described in claim 13, characterized in that, In the first monomer, at least one of R1, R2, and R3 is a vinyl group, and in the second monomer, at least one of R4 and R5 is selected from any one of mercapto, vinyl, and acrylate groups.

16. The method for preparing a single battery cell as described in claim 13, characterized in that, In the first monomer, at least one of R1, R2, and R3 is an acrylate group, and in the second monomer, at least one of R4 and R5 is selected from either vinyl or acrylate groups.

17. The method for preparing a battery cell according to any one of claims 13 to 16, characterized in that, The anchoring structure includes at least one of hydrogen atom, halogen atom, hydroxyl group, amino group, substituted alkyl group and alkoxy group, wherein the substituent in the substituted alkyl group includes hydroxyl group, amino group or halogen atom.

18. The method for preparing a battery cell according to any one of claims 13 to 17, characterized in that, The polymerization reaction conditions include heat treatment at 40℃-80℃ for 10h-24h.

19. The method for preparing a battery cell according to any one of claims 13 to 18, characterized in that, The molar ratio of the first monomer to the second monomer is 2:(3-5).

20. A battery device, characterized in that, It includes multiple battery cells as described in any one of claims 1-12 or multiple battery cells prepared by the preparation method as described in any one of claims 13-19.

21. An electrical appliance, characterized in that, Includes a battery cell as described in any one of claims 1-12 or a battery device as described in claim 20.

22. A gel electrolyte, characterized in that, It includes a polymer matrix and an electrolyte. The polymer matrix includes a first structural unit and a second structural unit. The first structural unit has the structural formula shown in formula (I), and the second structural unit has the structural formula shown in formula (II). The first structural unit and the second structural unit are connected by at least one chemical bond selected from urethane bonds, urea bonds, carbon-sulfur single bonds, carbon-carbon single bonds, and ester bonds; Wherein, * indicates a connection point; M1, M2, M3, M4, M5, and M6 each individually include an anchoring structure; n is any natural number from 2 to 2000, and m is any natural number from 20 to 2000.

23. The gel electrolyte as described in claim 22, characterized in that, The anchoring structure includes at least one of hydrogen atom, halogen atom, hydroxyl group, amino group, substituted alkyl group and alkoxy group, wherein the substituent in the substituted alkyl group includes hydroxyl group, amino group or halogen atom.

24. The gel electrolyte as described in claim 22 or 23, characterized in that, The electrolyte includes a solvent and a lithium salt, and the solvent includes ether solvents.

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