Composite solid electrolyte, method for preparing the same, and solid-state battery

Abstract

The application provides a composite solid electrolyte, a preparation method thereof and a solid-state battery. The composite solid electrolyte comprises a condensed matrix and electrolyte lithium salt, functional lithium salt and additives dispersed in the condensed matrix. The condensed matrix comprises a condensed polymer, an initiator and an organic solvent. The functional lithium salt in the composite solid electrolyte can improve the conductivity of the electrolyte and the lithium ion transference number, and enhance the ion conductivity of the electrolyte. At the same time, the functional lithium salt can help to improve the compatibility of the electrolyte with the electrode material, reduce the dissolution of metal ions, reduce the surface film impedance of the electrode, form a stable and good ion-conducting passivation film, improve the rate performance and cycle life of the battery, and improve the safety and stability of the battery.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, and relates to a composite solid electrolyte, its preparation method, and a solid battery. Background Technology

[0002] As lithium-ion solid-state batteries play an increasingly important role in various fields of modern society, the demand for their rate performance and safety is constantly growing. Traditional lithium-ion solid-state batteries use condensed solid electrolytes, which suffer from increased internal polarization, uneven lithium metal deposition, and lithium dendrite formation during high-rate charge and discharge. The heat generated also raises the battery temperature, posing a potential safety hazard of spontaneous combustion. Using a non-flammable solid electrolyte to replace some of the flammable liquid organic matter makes solid-state batteries less flammable and more heat-resistant, while also resisting external stress and impact, reducing the risk of thermal runaway and significantly improving battery safety. The retained portion of liquid organic matter provides better interfacial contact and maintains good ion mobility, which is beneficial for battery performance, improves conductivity and interfacial contact, and enhances charge and discharge performance.

[0003] The aforementioned solution utilizes a solid-state electrolyte with good flexibility and adaptability, allowing it to be bent to a certain extent and suitable for different packaging forms and application scenarios. It can adapt to various equipment requirements and has high compatibility with existing lithium-ion battery processes, enabling production on existing production lines and reducing production costs and the difficulty of technology transition. However, the solid-state electrolytes used in existing technologies have poor ion-conducting capabilities, affecting the performance of solid-state batteries. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a composite solid electrolyte, its preparation method, and a solid-state battery. The functional lithium salt in the composite solid electrolyte can improve the electrolyte's conductivity and lithium-ion transference number, enhancing its ion-conducting ability. Simultaneously, it helps improve the compatibility between the electrolyte and electrode materials, reduces metal ion dissolution, lowers electrode surface film impedance, forms a stable passivation film with good ion-conducting properties, improves the battery's rate performance and cycle life, and enhances battery safety and stability.

[0005] To achieve this objective, the present invention employs the following technical solution: In a first aspect, the present invention provides a composite solid electrolyte, the composite solid electrolyte comprising a coagulation matrix and an electrolyte lithium salt, a functional lithium salt and an additive dispersed within the coagulation matrix, wherein the coagulation matrix comprises a coagulation polymer, an initiator and an organic solvent; The functional lithium salt includes , or R1, R2, R3, and R4 independently include any one or at least two of the following: hydrogen atom, fluorine atom, cyano group, trifluoromethyl group, trimethylsilyl group, and unsaturated alkane.

[0006] Preferably, the mass fraction of the functional lithium salt is 0.1% to 5%, based on the mass of the composite solid electrolyte as 100%.

[0007] Preferably, the electrolyte lithium salt comprises lithium hexafluorophosphate.

[0008] Preferably, the mass fraction of the electrolyte lithium salt is 10% to 15%, based on the mass of the composite solid electrolyte being 100%.

[0009] Preferably, the polymeric material comprises any one or a combination of at least two of the following: polycarbonate, polyacrylate, polyurethane, polycaprolactone, polyphosphate, polylactide, polyethylene oxide, polyvinylidene fluoride, polyvinylidene chloride, polypropylene oxide, polyacrylonitrile, polytetrafluoroethylene, polyimide, polyetheretherketone, polymethyl methacrylate, polymethyl propionate, polytetrahydrofuran, polyethylene oxide, poly(1,3-dioxolane) or poly(1,4-dioxane).

[0010] Preferably, the mass fraction of the aggregated polymer is 1% to 20%, based on the mass of the composite solid electrolyte being 100%.

[0011] Preferably, the initiator includes any one or a combination of at least two of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, or isobenzopropanediol peroxide.

[0012] Preferably, the initiator has a mass fraction of 0.05% to 1.1% based on the mass of the composite solid electrolyte being 100%.

[0013] Preferably, the organic solvent includes any one or a combination of at least two of the following: ether solvents, nitrile solvents, carbonate solvents, or carboxylic acid ester solvents.

[0014] Preferably, the organic solvent comprises any one or a combination of at least two of the following: ethylene glycol methyl difluoroethyl ether, ethylene glycol methyl trifluoroethyl ether, ethylene glycol methyl tetrafluoropropyl ether, ethylene glycol bis(difluoroethyl) ether, ethylene glycol bis(trifluoroethyl) ether, ethylene glycol bis(tetrafluoropropyl) ether, tri(2,2,2-trifluoroethyl) orthoformate, bis(2,2,2-trifluoroethyl) ether, ethylene glycol dimethyl ether, acetonitrile, succinic acid, glutaronitrile, hexanetrionitrile, adiponitrile, heptacyanine, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl acetate, ethyl acetate, ethyl propionate, or propyl propionate.

[0015] Preferably, the organic solvent has a mass fraction of 50% to 90%, based on the mass of the composite solid electrolyte being 100%.

[0016] Preferably, the additive includes vinylene carbonate and / or fluoroethylene carbonate.

[0017] Preferably, the mass fraction of the additive is 0.5% to 10%, based on the mass of the composite solid electrolyte as 100%.

[0018] In a second aspect, the present invention provides a method for preparing a composite solid electrolyte as described in the first aspect, the method comprising the following steps: A precursor solution is obtained by mixing a polymer monomer, an initiator, an organic solvent, an electrolyte lithium salt, a functional lithium salt, and additives. The precursor solution is injected into a container and then subjected to hot pressing to obtain a composite solid electrolyte.

[0019] Preferably, the temperature of the hot pressing treatment is 45℃~55℃.

[0020] Preferably, the pressure of the hot pressing treatment is 4.5 kf / g to 5.5 kf / g.

[0021] Thirdly, the present invention provides a solid-state battery comprising a composite solid-state electrolyte as described in the first aspect.

[0022] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) The composite solid electrolyte of the present invention has a high lithium-ion mobility (>4mS / cm) at room temperature, while inhibiting irreversible lithium-ion deposition and lithium dendrite formation, which significantly alleviates the reduction of battery usable capacity and irreversible loss under high current charging and discharging conditions.

[0024] (2) The functional lithium salt in the composite solid electrolyte of the present invention can form a thin and dense SEI film on the surface of the negative electrode of a lithium-ion solid-state battery, and its main component is Li. x PO y F z LiF exhibits low interfacial impedance, making it particularly suitable for high-rate discharge. Furthermore, this functional lithium salt promotes the formation of a stable CEI film at the cathode, effectively suppressing the oxidative decomposition of the electrolyte and the breakdown of the electrode material structure.

[0025] (5) The composite solid electrolyte of this invention can significantly improve the rate performance and cycle life of lithium-ion solid batteries, enhance battery safety and stability, and has good compatibility with various positive and negative electrode materials. The preparation method of the composite solid electrolyte is simple, and all steps are carried out under well-controlled environmental conditions, which is conducive to large-scale production and improves production efficiency and product quality consistency. Attached Figure Description

[0026] Figure 1 This is a discharge capacity graph showing the solid-state batteries prepared in Application Example 3 and Comparative Application Example 1 after being discharged at different rates: 0.5C, 1C, 2C, 3C, 5C, and 10C for 5 cycles, followed by 10 cycles at 0.5C. Figure 2 This is a comparison chart of the capacity retention rates of solid-state batteries prepared in Application Example 1, Application Example 3, and Comparative Application Example 1 under 5C cycling. Detailed Implementation

[0027] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0028] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0029] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0030] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0031] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined according to its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order in which they are written or in any order that does not conflict with the technology.

[0032] In a first aspect, the present invention provides a composite solid electrolyte in one specific embodiment, the composite solid electrolyte comprising a coagulation matrix and an electrolyte lithium salt, a functional lithium salt and an additive dispersed within the coagulation matrix, wherein the coagulation matrix comprises a coagulation polymer, an initiator and an organic solvent; The functional lithium salt includes , or R1, R2, R3 and R4 independently include any one or at least two of the following: hydrogen atom, fluorine atom, cyano group, trifluoromethyl group, trimethylsilyl group, and unsaturated alkane, and are not all hydrogen atoms.

[0033] The composite solid electrolyte of this invention incorporates functional lithium salts. The fluorine atoms and cyano groups in these functional lithium salts possess strong electron-withdrawing properties, effectively weakening the coordination between cations and anions in the lithium salt, thereby enhancing the migration ability of lithium ions and significantly improving the lithium ion mobility in the electrolyte. Furthermore, these structures endow the electrolyte with excellent antioxidant properties, enabling the formation of a thin yet robust interface layer on the electrode surface. This interface layer exhibits good ionic conductivity. This interface layer helps reduce the film impedance on the electrode surface, minimizing the severe capacity decay of the battery under high-rate charge-discharge conditions.

[0034] In some embodiments, the mass fraction of the functional lithium salt is 0.1% to 5%, based on the mass of the composite solid electrolyte as 100%, for example: 0.1%, 0.5%, 1%, 2% or 5%, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0035] The functional lithium salt of the present invention includes This is denoted as equation (I-1). This is denoted as equation (I-2). This is denoted as equation (I-3). This is denoted as equation (I-4). Noted as equation (I-5), This is denoted as equation (II-1). This is denoted as equation (II-2). This is denoted as equation (III-1). This is denoted as equation (III-2). It is denoted as equation (III-3).

[0036] In some embodiments, the electrolyte lithium salt comprises lithium hexafluorophosphate.

[0037] In some embodiments, the mass fraction of the electrolyte lithium salt is 10% to 15%, based on the mass of the composite solid electrolyte as 100%, for example: 10%, 11%, 12%, 13%, 14% or 15%, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0038] In some embodiments, the coagulated polymer includes any one or a combination of at least two of polycarbonate, polyacrylate, polyurethane, polycaprolactone, polyphosphate, polylactide, polyethylene oxide, polyvinylidene fluoride, polyvinylidene chloride, polypropylene oxide, polyacrylonitrile, polytetrafluoroethylene, polyimide, polyetheretherketone, polymethyl methacrylate, polymethyl propionate, polytetrahydrofuran, polyethylene oxide, poly(1,3-dioxolane) or poly(1,4-dioxane), with typical but non-limiting combinations including combinations of polycarbonate and polyacrylate, polycaprolactone and polyphosphate, or poly(1,3-dioxolane) and poly(1,4-dioxane), etc.

[0039] In some embodiments, the mass fraction of the aggregated polymer is 1% to 20% based on the mass of the composite solid electrolyte being 100%, for example: 1%, 5%, 10%, 15% or 20%, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] In some embodiments, the initiator includes any one or a combination of at least two of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, benzoyl peroxide, or isobenzoyl hydroperoxide. Typical but non-limiting combinations include combinations of azobisisobutyronitrile and azobisisoheptanenitrile, combinations of azobisisoheptanenitrile and benzoyl peroxide, or combinations of benzoyl peroxide and isobenzoyl hydroperoxide.

[0041] In some embodiments, the mass fraction of the initiator is 0.05% to 1.1% based on the mass of the composite solid electrolyte as 100%, for example: 0.05%, 0.1%, 0.5%, 0.8% or 1.1%, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0042] In some embodiments, the organic solvent includes any one or a combination of at least two of ether solvents, nitrile solvents, carbonate solvents or carboxylic acid ester solvents. Typical but non-limiting combinations include combinations of ether solvents and nitrile solvents, combinations of nitrile solvents and carbonate solvents, or combinations of carbonate solvents and carboxylic acid ester solvents.

[0043] In some embodiments, the organic solvent includes any one or a combination of at least two of ethylene glycol methyl difluoroethyl ether, ethylene glycol methyl trifluoroethyl ether, ethylene glycol methyl tetrafluoropropyl ether, ethylene glycol bis(difluoroethyl) ether, ethylene glycol bis(trifluoroethyl) ether, ethylene glycol bis(tetrafluoropropyl) ether, tri(2,2,2-trifluoroethyl) orthocarbamate, bis(2,2,2-trifluoroethyl) ether, ethylene glycol dimethyl ether, acetonitrile, succinic acid nitrile, glutaronitrile, hexanetrionitrile, adiponitrile, heptacyanide, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl acetate, ethyl acetate, ethyl propionate, or propyl propionate. Typical but non-limiting combinations include combinations of ethylene carbonate and propylene carbonate, combinations of acetonitrile and succinic acid nitrile, or combinations of ethylene glycol methyl difluoroethyl ether and ethylene glycol methyl trifluoroethyl ether.

[0044] In some embodiments, the mass fraction of the organic solvent is 50% to 90%, based on the mass of the composite solid electrolyte as 100%, for example: 50%, 60%, 70%, 80% or 90%, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] In some embodiments, the additives include vinylene carbonate and / or fluoroethylene carbonate.

[0046] In some embodiments, based on the mass of the composite solid electrolyte as 100%, the mass fraction of the additive is 0.5% to 10%, for example: 0.5%, 1%, 2%, 5% or 10%, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0047] In a second aspect, the present invention provides a method for preparing a composite solid electrolyte as described in the first aspect, the method comprising the following steps: A precursor solution is obtained by mixing a polymer monomer, an initiator, an organic solvent, an electrolyte lithium salt, a functional lithium salt, and additives. The precursor solution is injected into a container and then subjected to hot pressing to obtain a composite solid electrolyte.

[0048] In some embodiments, the temperature of the hot pressing treatment is 45°C to 55°C, for example: 45°C, 48°C, 50°C, 52°C or 55°C, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] In some embodiments, the pressure of the hot pressing treatment is 4.5 kf / g to 5.5 kf / g, for example: 4.5 kf / g, 4.8 kf / g, 5 kf / g, 5.2 kf / g or 5.5 kf / g, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] Thirdly, the present invention provides a solid-state battery comprising a composite solid-state electrolyte as described in the first aspect.

[0051] The composite solid electrolytes described in the examples and comparative examples were prepared by the following method: A precursor solution is obtained by mixing a polymer monomer, an initiator, an organic solvent, an electrolyte lithium salt, a functional lithium salt, and additives. The precursor solution is injected into a pouch cell (i.e., container), pre-packaged, and allowed to stand. It is then subjected to hot-pressing at 50°C and 5 kF / g to obtain a composite solid electrolyte. After aging, secondary packaging, and capacity testing, a solid-state battery is obtained. The preparation and injection of the precursor solution are carried out in a glove box at 20°C under an atmosphere of 99.999% pure argon gas, with a moisture content of less than 0.01 ppm.

[0052] Example 1 This embodiment provides a composite solid electrolyte. Based on the mass of the composite solid electrolyte (100%), the composite solid electrolyte comprises a coagulated matrix and dispersed within the coagulated matrix: 11.5% lithium hexafluorophosphate, 0.5% functional lithium salt (Formula I-1), and additives (0.6% vinylene carbonate and 5% fluoroethylene carbonate). The coagulated matrix comprises 7% poly(1,3-dioxolane), 0.08% azobisisobutyronitrile, and 75.82% organic solvent (EC and DMC in a volume ratio of 1:1.5).

[0053] Example 2 This embodiment provides a composite solid electrolyte. Based on the mass of the composite solid electrolyte (100%), the composite solid electrolyte comprises a coagulated matrix and dispersed within the coagulated matrix: 11.5% lithium hexafluorophosphate, 0.7% functional lithium salt (Formula I-1), and additives (0.6% vinylene carbonate and 5% fluoroethylene carbonate). The coagulated matrix comprises 7% poly(1,3-dioxolane), 0.08% azobisisobutyronitrile, and 75.82% organic solvent (EC and DMC in a volume ratio of 1:1.5).

[0054] Example 3 This embodiment provides a composite solid electrolyte. Based on the mass of the composite solid electrolyte (100%), the composite solid electrolyte comprises a coagulated matrix and dispersed within the coagulated matrix: 11.5% lithium hexafluorophosphate, 0.9% functional lithium salt (Formula I-1), and additives (0.6% vinylene carbonate and 5% fluoroethylene carbonate). The coagulated matrix comprises 7% poly(1,3-dioxolane), 0.08% azobisisobutyronitrile, and 75.82% organic solvent (EC and DMC in a volume ratio of 1:1.5).

[0055] Example 4 This embodiment provides a composite solid electrolyte. Based on the mass of the composite solid electrolyte (100%), the composite solid electrolyte comprises a coagulated matrix and dispersed within the coagulated matrix: 11.5% lithium hexafluorophosphate, 0.5% functional lithium salt (Formula I-2), and additives (0.6% vinylene carbonate and 5% fluoroethylene carbonate). The coagulated matrix comprises 7% poly(1,3-dioxolane), 0.08% azobisisobutyronitrile, and 75.82% organic solvent (EC and DMC in a volume ratio of 1:1.5).

[0056] Example 5 This embodiment provides a composite solid electrolyte. Based on the mass of the composite solid electrolyte (100%), the composite solid electrolyte comprises a coagulated matrix and dispersed within the coagulated matrix: 11.5% lithium hexafluorophosphate, 0.7% functional lithium salt (Formula I-1), and additives (0.6% vinylene carbonate and 5% fluoroethylene carbonate). The coagulated matrix comprises 7% poly(1,3-dioxolane), 0.08% azobisisobutyronitrile, and 75.82% organic solvent (EC and DMC in a volume ratio of 1:1.5).

[0057] Example 6 This embodiment provides a composite solid electrolyte. Based on the mass of the composite solid electrolyte (100%), the composite solid electrolyte comprises a coagulated matrix and dispersed within the coagulated matrix: 11.5% lithium hexafluorophosphate, 0.9% functional lithium salt (Formula I-1), and additives (0.6% vinylene carbonate and 5% fluoroethylene carbonate). The coagulated matrix comprises 7% poly(1,3-dioxolane), 0.08% azobisisobutyronitrile, and 75.82% organic solvent (EC and DMC in a volume ratio of 1:1.5).

[0058] Comparative Example 1 The only difference between this comparative example and Example 1 is that no functional lithium salt is added; all other conditions and parameters are exactly the same as in Example 1.

[0059] Application Example 1 This application example provides a solid-state battery, which includes an NCM523 positive electrode, a graphite negative electrode, and the composite solid electrolyte described in Example 1. The battery has a designed capacity of 2Ah.

[0060] Application Example 2 This application example provides a solid-state battery, which includes an NCM523 positive electrode, a graphite negative electrode, and the composite solid electrolyte described in Example 2. The battery has a designed capacity of 2Ah.

[0061] Application Example 3 This application example provides a solid-state battery comprising an NCM523 positive electrode, a graphite negative electrode, and the composite solid-state electrolyte described in Example 3, with a designed capacity of 2Ah.

[0062] Application Example 4 This application example provides a solid-state battery comprising an NCM523 positive electrode, a graphite negative electrode, and the composite solid-state electrolyte described in Example 4, with a designed capacity of 2Ah.

[0063] Application Example 5 This application example provides a solid-state battery comprising an NCM523 positive electrode, a graphite negative electrode, and the composite solid electrolyte described in Example 5, with a designed capacity of 2Ah.

[0064] Application Example 6 This application example provides a solid-state battery comprising an NCM523 positive electrode, a graphite negative electrode, and the composite solid-state electrolyte described in Example 6, with a designed capacity of 2Ah.

[0065] Application Example 7 This application example provides a solid-state battery, which includes a lithium cobalt oxide positive electrode, a graphite negative electrode, and the composite solid electrolyte described in Example 1. The battery has a designed capacity of 2Ah.

[0066] Application Example 8 This application example provides a solid-state battery comprising a lithium cobalt oxide cathode, a graphite anode, and the composite solid electrolyte described in Example 2, with a designed capacity of 2Ah.

[0067] Application Example 9 This application example provides a solid-state battery, which includes a lithium cobalt oxide positive electrode, a graphite negative electrode, and the composite solid electrolyte described in Example 3. The battery has a designed capacity of 2Ah.

[0068] Application Example 10 This application example provides a solid-state battery, which includes a lithium cobalt oxide positive electrode, a graphite negative electrode, and the composite solid electrolyte described in Example 4. The battery has a designed capacity of 2Ah.

[0069] Application Example 11 This application example provides a solid-state battery comprising a lithium cobalt oxide cathode, a graphite anode, and the composite solid electrolyte described in Example 5, with a designed capacity of 2Ah.

[0070] Application Example 12 This application example provides a solid-state battery comprising a lithium cobalt oxide cathode, a graphite anode, and the composite solid electrolyte described in Example 6, with a designed capacity of 2Ah.

[0071] Comparative Application Example 1 This comparative application example provides a solid-state battery comprising an NCM523 positive electrode, a graphite negative electrode, and the composite solid electrolyte described in Comparative Example 1, with a designed capacity of 2Ah.

[0072] Comparative Application Example 2 This comparative application example provides a solid-state battery comprising a lithium cobalt oxide cathode, a graphite anode, and the composite solid electrolyte described in Comparative Example 1, with a designed capacity of 2 Ah.

[0073] Performance testing: The solid-state batteries obtained from the corresponding use cases and comparative application examples were tested, and the test results are shown in Table 1: Table 1 As shown in Table 1, based on Application Examples 1 to 6 and Application Examples 7 to 12, the conductivity of the composite solid electrolyte described in Examples 1 to 6 of this invention ranges from 4.37 mS / cm to 6.64 mS / cm, while the conductivity of the solid electrolyte in Comparative Example 1 is only 1.98 mS / cm. Even with the addition of a small amount of functional lithium salt (0.1%), the conductivity of the solid electrolyte is still significantly improved. This indicates that the functional lithium salt added to the composite solid electrolyte of this invention can significantly enhance the ionic conductivity of the solid electrolyte, which is beneficial to improving the rate performance of the battery. Furthermore, the conductivity increases with the increase of the mass fraction of the two lithium salts. Furthermore, the composite solid electrolyte described in this invention can be applied to various solid-state batteries. Among them, in a pouch cell composed of two positive electrode materials (NCM523 and LiCO2) and a graphite negative electrode, a rate discharge test was conducted at 3~4.2V. When the amount of functional lithium salts (I-1) and (I-2) added to the solid electrolyte was 0.9wt%, the discharge capacities of the NCM523 battery (Application Example 3 and Application Example 6) and the LiCoO2 battery (Application Example 9 and Application Example 12) after 5 cycles of discharge at 4.2V at rates of 0.5C, 1C, 2C, 3C, 5C and 10C were 1.90Ah, 1.83Ah, 1.85Ah and 1.81Ah, respectively. The discharge capacities of the basic electrolyte (Comparative Application Example 1 and Comparative Application Example 2) tested under the same conditions were 0.41Ah and 0.37Ah, respectively.

[0074] Comparisons between Application Example 1 and Comparative Application Example 1, and between Application Example 7 and Comparative Application Example 2, show that the composite solid electrolyte of the present invention exhibits high lithium-ion mobility while suppressing irreversible lithium-ion deposition and lithium dendrite formation, thus mitigating the reduction in usable battery capacity and irreversible loss under high current. Furthermore, the functional lithium salt used in this invention can form a thin and dense Li-based layer on the surface of the negative electrode of the lithium-ion solid-state battery. x PO y F z The SEI film of LiF exhibits low interfacial impedance, making it suitable for high-rate discharge. Simultaneously, this functional lithium salt also helps form a stable CEI film on the positive electrode surface, effectively suppressing the oxidative decomposition of the electrolyte and the structural collapse of high-capacity positive electrode materials. Therefore, the technical solution of this invention can significantly improve the rate performance and cycle life of lithium-ion solid-state batteries, enhance battery safety and stability, and has good compatibility with various positive and negative electrode materials.

[0075] The discharge capacity of the solid-state battery prepared in Application Example 3 and Comparative Application Example 1 after being discharged at different rates (0.5C, 1C, 2C, 3C, 5C, and 10C) for 5 cycles, followed by 10 cycles at 0.5C, is shown in the graph below. Figure 1 As shown in the figure, the capacity retention rates of the solid-state batteries prepared in Application Example 1, Application Example 3, and Comparative Application Example 1 are compared under 5C cycling conditions. Figure 2 As shown, by Figure 1-2 It can be seen that the cycle stability and rate performance of solid-state batteries using the composite solid-state electrolyte described in this invention are significantly improved.

[0076] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A composite solid electrolyte, characterized in that, The composite solid electrolyte includes a coagulation matrix and electrolyte lithium salt, functional lithium salt and additives dispersed within the coagulation matrix. The coagulation matrix includes coagulation polymer monomers, initiators and organic solvents. The functional lithium salt includes , or R1, R2, R3, and R4 independently include any one or at least two of the following: hydrogen atom, fluorine atom, cyano group, trifluoromethyl group, trimethylsilyl group, and unsaturated alkane.

2. The composite solid electrolyte as described in claim 1, characterized in that, Based on the mass of the composite solid electrolyte being 100%, the mass fraction of the functional lithium salt is 0.1% to 5%.

3. The composite solid electrolyte as described in claim 1 or 2, characterized in that, The electrolyte lithium salt includes lithium hexafluorophosphate; And / or, based on the mass of the composite solid electrolyte as 100%, the mass fraction of the electrolyte lithium salt is 10%~15%.

4. The composite solid electrolyte according to any one of claims 1-3, characterized in that, The condensed polymer includes any one or a combination of at least two of the following: polycarbonate, polyacrylate, polyurethane, polycaprolactone, polyphosphate, polylactide, polyethylene glycol, polyvinylidene fluoride, polyvinylidene chloride, polypropylene oxide, polyacrylonitrile, polytetrafluoroethylene, polyimide, polyetheretherketone, polymethyl methacrylate, polymethyl propionate, polytetrahydrofuran, polyethylene oxide, poly(1,3-dioxolane) or poly(1,4-dioxane). And / or, based on the mass of the composite solid electrolyte being 100%, the mass fraction of the aggregated polymer is 1% to 20%.

5. The composite solid electrolyte according to any one of claims 1-4, characterized in that, The initiator includes any one or a combination of at least two of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide or isobenzopropane hydroperoxide; And / or, based on the mass of the composite solid electrolyte as 100%, the mass fraction of the initiator is 0.05% to 1.1%.

6. The composite solid electrolyte according to any one of claims 1-5, characterized in that, The organic solvent includes any one or a combination of at least two of the following: ether solvents, nitrile solvents, carbonate solvents, or carboxylic acid ester solvents; And / or, the organic solvent comprises any one or a combination of at least two of the following: ethylene glycol methyl difluoroethyl ether, ethylene glycol methyl trifluoroethyl ether, ethylene glycol methyl tetrafluoropropyl ether, ethylene glycol bis(difluoroethyl) ether, ethylene glycol bis(trifluoroethyl) ether, ethylene glycol bis(tetrafluoropropyl) ether, tri(2,2,2-trifluoroethyl) orthoformate, bis(2,2,2-trifluoroethyl) ether, ethylene glycol dimethyl ether, acetonitrile, succinic anionyl ether, glutaronitrile, hexanetrionitrile, adiponitrile, heptacyanine, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl acetate, ethyl acetate, ethyl propionate, or propyl propionate; And / or, based on the mass of the composite solid electrolyte being 100%, the mass fraction of the organic solvent is 50% to 90%.

7. The composite solid electrolyte according to any one of claims 1-6, characterized in that, The additives include vinylene carbonate and / or fluoroethylene carbonate; And / or, based on the mass of the composite solid electrolyte as 100%, the mass fraction of the additive is 0.5% to 10%.

8. A method for preparing a composite solid electrolyte as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: A precursor solution is obtained by mixing a polymer monomer, an initiator, an organic solvent, an electrolyte lithium salt, a functional lithium salt, and additives. The precursor solution is injected into a container and then subjected to hot pressing to obtain a composite solid electrolyte.

9. The preparation method according to claim 8, characterized in that, The temperature for the hot pressing process is 45℃~55℃; And / or, the pressure of the hot pressing treatment is 4.5 kgf to 5.5 kgf.

10. A solid-state battery, characterized in that, The solid-state battery comprises a composite solid-state electrolyte as described in any one of claims 1-7.

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