Solid electrolyte precursors, solid electrolytes and solid lithium batteries

Abstract

This application discloses a solid electrolyte precursor, a solid electrolyte, and a solid lithium battery, relating to the technical field of solid electrolytes; the solid electrolyte precursor is processed to form a solid electrolyte containing thiourea structural units, the thiourea structural units containing N-H groups capable of participating in hydrogen bonding; the solid electrolyte exhibits an ionic conductivity of not less than 1.6 × 10⁻⁶ at 25°C. ‑4 S·cm ‑1 This application describes a solid electrolyte formed from a solid electrolyte precursor. The solid electrolyte contains thiourea structural units and forms a polymer network structure with modified inorganic fillers as connecting points. This improves the interfacial compatibility between inorganic and organic materials in the solid electrolyte and forms a continuous conductive path in the solid electrolyte, thereby increasing the ionic conductivity of the solid electrolyte.

Description

Technical Field

[0001] This application relates to the technical field of solid electrolytes, specifically to solid electrolyte precursors, solid electrolytes, and solid lithium batteries. Background Technology

[0002] Solid-state electrolytes are considered a key approach to solving the safety issues of traditional lithium metal batteries, among which organic polymer / inorganic filler composite solid-state electrolytes have attracted widespread attention. Currently, however, organic polymer / inorganic filler composite solid-state electrolytes suffer from problems such as poor interfacial compatibility between the organic polymer and the inorganic filler.

[0003] Although various improvement strategies have been proposed in the existing technology, such as reducing the particle size of inorganic fillers and improving the arrangement order of inorganic fillers, the interfacial compatibility between the organic polymer and inorganic fillers inside the composite solid electrolyte is still relatively poor, resulting in poor performance of the solid electrolyte. Summary of the Invention

[0004] The first aspect of this application provides a solid electrolyte precursor comprising: a modified inorganic filler, a chain extender, and a crosslinking agent, wherein the crosslinking agent comprises diisothiocyanate, and both the modified inorganic filler and the chain extender can react with the crosslinking agent to form thiourea structural units.

[0005] In some optional embodiments of the first aspect of this application, both the modified inorganic filler and the chain extender include amino groups.

[0006] In some optional embodiments of the first aspect of this application, the mass ratio of modified inorganic filler to crosslinking agent is 1:(0.5~2).

[0007] In some optional embodiments of the first aspect of this application, the mass ratio of modified inorganic filler to chain extender is 1:(2~9).

[0008] In some optional embodiments of the first aspect of this application, the mass ratio of the modified inorganic filler to the chain extender and to the crosslinking agent is (3~12):1.

[0009] In some optional embodiments of the first aspect of this application, the crosslinking agent includes at least one selected from phenylene diisothiocyanate, 1,3-phenylene diisothiocyanate, 1,6-hexanediisothiocyanate and 1,2-phenylene diisothiocyanate.

[0010] In some optional embodiments of the first aspect of this application, the chain extender includes at least one of 1,8-octanediamine, polyoxyethylenediamine, O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol, poly(dimethylsiloxane)bis(3-aminopropyl)-terminated and adipamide.

[0011] In some optional embodiments of the first aspect of this application, the modified inorganic filler is prepared by an inorganic filler and a silane coupling agent, and the preparation method of the modified inorganic filler includes:

[0012] The inorganic filler is mixed with a first organic solvent to obtain a suspension. A silane coupling agent and water are added to the suspension. The suspension is refluxed at 40℃~100℃ for 2h~10h, then cooled and centrifuged to obtain a solid. The solid is dried to obtain the modified inorganic filler.

[0013] In some optional embodiments of the first aspect of this application, the silane coupling agent includes at least one selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane and γ-ureopropyltriethoxysilane.

[0014] In some optional embodiments of the first aspect of this application, the inorganic filler includes at least one of alumina, LLZTO, LLZO, LAGP, LATP and titanium dioxide.

[0015] A second aspect of this application provides a solid electrolyte, prepared from the aforementioned solid electrolyte precursor. The preparation steps of the solid electrolyte include:

[0016] Under an inert gas atmosphere, a solid electrolyte precursor, lithium salt, and a second organic solvent are mixed to obtain a mixture. The mixture is stirred and reacted at 50℃~100℃ for 10h~48h. After the reaction is completed, the mixture is dried to obtain a solid electrolyte.

[0017] In some optional embodiments of the second aspect of this application, drying the mixture to obtain a solid electrolyte includes: coating the mixture onto a substrate and drying it at 30°C to 80°C for 8 hours to 24 hours to obtain a solid electrolyte having a film structure.

[0018] A third aspect of this application provides a solid-state lithium battery, including a positive electrode, a negative electrode, and a solid electrolyte as described above.

[0019] Beneficial effects:

[0020] The first aspect of this application provides a solid electrolyte precursor, and a solid electrolyte formed from the solid electrolyte precursor. The solid electrolyte contains thiourea structural units, which improve the interfacial compatibility between inorganic and organic materials in the solid electrolyte and form a continuous conductive path in the solid electrolyte, thereby improving the ionic conductivity of the solid electrolyte.

[0021] The solid electrolyte provided in the second aspect of this application contains a chain extender, which gives the solid electrolyte good flexibility. Moreover, the polymer network structure formed by the modified inorganic filler, diisothiocyanate and chain extender gives the solid electrolyte a continuous and efficient ion transport channel. As a result, the solid electrolyte exhibits high ionic conductivity at room temperature and also has good mechanical strength.

[0022] The solid-state lithium battery provided in the third aspect of this application has good initial discharge capacity, cycle stability and high coulombic efficiency, and good overall electrochemical performance. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the solid electrolyte precursor reaction in Example 1 of this application. Detailed Implementation

[0024] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present application and are not intended to limit the present application.

[0025] In one embodiment, a solid electrolyte precursor is provided, comprising: a modified inorganic filler, a chain extender, and a crosslinking agent, wherein the crosslinking agent comprises diisothiocyanate, and both the modified inorganic filler and the chain extender can react with the crosslinking agent to form thiourea structural units.

[0026] In some optional embodiments of this application, both the modified inorganic filler and the chain extender include amino groups.

[0027] In this embodiment, the modified inorganic filler serves to transport lithium ions, broaden the electrochemical window, and enhance the mechanical strength of the solid electrolyte. The chain extender provides flexible chains, improves the flexibility of the solid electrolyte, and further enhances its lithium-ion transport performance.

[0028] In this embodiment, during the formation of the solid electrolyte precursor, the amino groups on the modified inorganic filler react with the "–N=C=S" bonds in the diisothiocyanate to generate thiourea structural units "–NH–C(=S)–NH–" (hereinafter referred to as thiourea bonds). The amino groups on the chain extender also react with the "–N=C=S" bonds in the diisothiocyanate to form thiourea bonds. In other words, the amino groups in the modified inorganic filler and the chain extender undergo affinity addition reactions with the diisothiocyanate to generate thiourea derivatives, forming a polymer network structure with the modified inorganic filler as the connecting point. This improves the interfacial compatibility between inorganic and organic materials in the solid electrolyte, forming a continuous conductive path and thus increasing the ionic conductivity of the solid electrolyte. In this embodiment, a bridge is established between the inorganic and organic material interfaces through chemical bonds, enhancing the interaction between the inorganic and organic material interfaces, thereby improving interfacial affinity and achieving a highly efficient interfacial ion transport network.

[0029] It is worth noting that thiourea bonds in polymer networks possess both hydrogen bonding interactions and dynamic covalent properties, and these two characteristics work synergistically to enhance the overall performance of solid electrolytes. Specifically, a thiourea bond contains two NH bonds and one thiocarbonyl C=S group. NH atoms act as hydrogen bond donors, while the lone pairs of electrons on the sulfur and nitrogen atoms act as hydrogen bond acceptors, enabling the thiourea bond to form multiple hydrogen bonds. This ability to form multiple hydrogen bonds allows the thiourea bond to form a strong and reversible hydrogen bond network between polymer chains. This network preferentially breaks under stress in the solid electrolyte material, effectively dissipating energy and thus enhancing the toughness and mechanical adaptability of the solid electrolyte system. Moreover, thiourea is generated in situ from amines and isothiocyanates, a reversible reaction that gives the thiourea bond a macroscopically dynamic covalent characteristic. This allows for reversible breaking and recombination under moderate thermodynamic or environmental stimuli, enabling the reconstruction of the polymer network topology and giving the solid electrolyte material a self-healing capability.

[0030] The dynamic covalent properties of thiourea bonds interact with hydrogen bonds. Hydrogen bonds provide transient, reversible non-covalent crosslinking to maintain elasticity and stiffness, while the dynamic covalent properties drive polymer network repair and recovery over a longer timescale. This not only optimizes the stiffness, toughness, and elasticity of solid electrolytes, but also extends their service life in electrochemical devices such as batteries.

[0031] In some optional embodiments of this application, the mass ratio of modified inorganic filler to crosslinking agent is 1:(0.5~2). This setting ensures that the crosslinking agent can be fully bonded to the surface of the modified inorganic filler, preventing the agglomeration of the modified inorganic filler during polymerization and providing sufficient active sites for reaction with the chain extender. At the same time, it avoids excessive crosslinking of the crosslinking agent, which could lead to localized over-crosslinking and brittleness.

[0032] In some optional embodiments of this application, the mass ratio of modified inorganic filler to chain extender is 1:(2~9). This setting ensures that the chain extender fully connects the modified inorganic filler units after reacting with the crosslinking agent, forming a continuous polymer matrix rich in flexible segments in the reaction system, providing good chain segment movement freedom, and enhancing the migration ability of lithium ions in the polymer phase.

[0033] In some optional embodiments of this application, the mass ratio of the modified inorganic filler to the chain extender and to the crosslinking agent is (3~12):1. This configuration ensures that the crosslinking agent provides sufficient crosslinking points to maintain the stability of the polymer network structure; simultaneously, it retains some uncrosslinked or lightly crosslinked flexible segments, guaranteeing high ionic conductivity and good interfacial wettability, achieving a synergistic balance between high flexibility and high stability.

[0034] In some optional embodiments of this application, the crosslinking agent includes at least one of phenylene diisothiocyanate, 1,3-phenylene diisothiocyanate, 1,6-hexanediisothiocyanate and 1,2-phenylene diisothiocyanate.

[0035] In some optional embodiments of this application, the chain extender includes at least one of 1,8-octanediamine, polyoxyethylenediamine, O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol, poly(dimethylsiloxane)bis(3-aminopropyl)-terminated and adipamide.

[0036] In some optional embodiments of this application, the modified inorganic filler is prepared by an inorganic filler and a silane coupling agent, and the preparation method of the modified inorganic filler includes:

[0037] The inorganic filler is mixed with a first organic solvent to obtain a suspension. A silane coupling agent and water are added to the suspension. The suspension is refluxed at 40℃~100℃ for 2h~10h, then cooled and centrifuged to obtain a solid. The solid is dried to obtain the modified inorganic filler.

[0038] In some optional embodiments of this application, the silane coupling agent includes at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane and γ-ureopropyltriethoxysilane.

[0039] In some optional embodiments of this application, the inorganic filler includes at least one of alumina, LLZTO, LLZO, LAGP, LATP and titanium dioxide.

[0040] In some optional embodiments of this application, the first organic solvent includes at least one of toluene, dimethylformamide, and anhydrous ethanol.

[0041] In this embodiment, a silane coupling agent is used to modify the inorganic filler. The modification mechanism of the silane coupling agent is as follows: the alkoxy group in the silane coupling agent hydrolyzes to generate Si-OH, the Si-OH condenses to form an oligomer, and the oligomer reacts with the hydroxyl groups on the surface of the inorganic material through dehydration condensation to form the modified inorganic filler.

[0042] In another embodiment, a solid electrolyte is provided, prepared from the above-described solid electrolyte precursor. The preparation steps of the solid electrolyte are as follows:

[0043] Under an inert gas atmosphere, a solid electrolyte precursor, a lithium salt, and a second organic solvent are mixed to obtain a mixture. The mixture is stirred and reacted at 50°C to 100°C for 10 to 48 hours. After the reaction is completed, the mixture is dried to obtain a solid electrolyte.

[0044] In some optional embodiments of this application, the second organic solvent includes at least one of dimethylformamide, N-methylpyrrolidone, acetonitrile, and tetrahydrofuran.

[0045] In this embodiment, the mass ratio of modified inorganic filler to lithium salt is 1:(1~4). The lithium salt includes at least one of LiFSI, LiBOB, LiPF6, LiClO4, LiTFSI, LiNO3, and LiDFOB.

[0046] In some optional embodiments of this application, drying the mixture to obtain a solid electrolyte includes: coating the mixture onto a substrate and drying it at 30°C to 80°C for 8 hours to 24 hours to obtain a solid electrolyte having a film structure.

[0047] In another embodiment, a solid-state lithium battery is provided, including a positive electrode, a negative electrode, and a solid electrolyte as described above.

[0048] In this embodiment, there are no special requirements for the positive and negative electrodes; any lithium electrode positive and negative electrodes well-known to those skilled in the art can be used. For example, the positive electrode includes a positive electrode active material, a current collector, a conductive agent, and a binder. The positive electrode active material includes at least one of lithium iron manganese phosphate, lithium manganese oxide, lithium cobalt oxide, and lithium iron phosphate; the current collector includes aluminum foil or copper foil; the conductive agent includes at least one of carbon nanotubes, Ketjen black, and acetylene black; the binder includes at least one of polytetrafluoroethylene, polyurethane, and polyvinylidene fluoride; and the negative electrode includes metallic lithium.

[0049] This embodiment does not have any special requirements for the assembly method of the solid-state lithium battery; any assembly method well known to those skilled in the art can be used.

[0050] The present application is further illustrated below with reference to embodiments and comparative examples. Unless otherwise specified, the raw materials, reagents, materials and equipment used in this application are all commercially available products conventionally used in the art.

[0051]

Example 1

[0052] S1. Add 10g LLZTO to 100mL toluene and sonicate for 30min to obtain a homogeneous suspension. Then add 1g 3-aminopropyltrimethoxysilane and 0.2mL deionized water to the suspension, reflux at 80℃ for 4h, cool to room temperature, centrifuge four times, and finally dry the centrifuged LLZTO in a vacuum oven at 30℃ for 24h to obtain LLZTO modified with 3-aminopropyltrimethoxysilane, i.e., modified inorganic filler. The LLZTO modified with 3-aminopropyltrimethoxysilane is denoted as LLZTO@ATS.

[0053] S2. Under a nitrogen atmosphere, 0.46 g LLZTO@ATS, 1.9 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g terephthalic diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0054] S3. After the reaction is complete, the mixture is coated onto a PP plate and dried in an oven at 60°C for 12 hours to obtain a solid electrolyte membrane.

[0055]

Example 2

[0056] Example 2 differs from Example 1 in the amount of LLZTO@ATS used; the other steps are the same. Specifically:

[0057] S1 is the same as in Example 1.

[0058] S2. Under a nitrogen atmosphere, 0.23 g LLZTO@ATS, 1.9 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g terephthalic diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0059] S3 is the same as in Example 1.

[0060]

Example 3

[0061] Example 3 differs from Example 1 in the amount of LLZTO@ATS used; the other steps are the same. Specifically:

[0062] S1 is the same as in Example 1.

[0063] S2. Under a nitrogen atmosphere, 0.69 g LLZTO@ATS, 1.9 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g terephthalic diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0064] S3 is the same as in Example 1.

[0065]

Example 4

[0066] S1. Add 10g of LAGP to 100mL of toluene and sonicate for 30min to obtain a homogeneous suspension. Then, add 1g of 3-aminopropyltrimethoxysilane and 0.2mL of deionized water to the suspension, reflux at 80℃ for 4h, cool to room temperature, centrifuge four times, and finally dry the centrifuged LAGP in a vacuum oven at 30℃ for 24h to obtain LAGP modified with 3-aminopropyltrimethoxysilane. The LAGP modified with 3-aminopropyltrimethoxysilane is denoted as LAGP@ATS.

[0067] S2. Under a nitrogen atmosphere, 0.46 g LAGP@ATS, 1.9 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g 1,6-hexanediisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0068] S3. The solid electrolyte is coated onto a PP plate and dried in an oven at 60°C for 12 hours to obtain a solid electrolyte membrane.

[0069]

Example 5

[0070] Example 5 differs from Example 1 in the amount of p-phenylenediisothiocyanate used; the remaining steps are the same. Specifically:

[0071] S1 is the same as in Example 1.

[0072] S2. Under a nitrogen atmosphere, 0.46 g LLZTO@ATS, 1.9 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.736 g terephthalic diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0073] S3 is the same as in Example 1.

[0074]

Example 6

[0075] Example 6 differs from Example 1 in the amount of p-phenylenediisothiocyanate used; the remaining steps are the same. Specifically:

[0076] S1 is the same as in Example 1.

[0077] S2. Under a nitrogen atmosphere, 0.46 g LLZTO@ATS, 1.9 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.23 g terephthalic diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0078] S3 is the same as in Example 1.

[0079]

Example 7

[0080] Example 7 differs from Example 1 in the amount of LLZTO@ATS and O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol used; the remaining steps are the same. Specifically:

[0081] S1 is the same as in Example 1.

[0082] S2. Under a nitrogen atmosphere, 0.30 g LLZTO@ATS, 2.06 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g terephthalic diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0083] S3 is the same as in Example 1.

[0084]

Example 8

[0085] Example 8 differs from Example 1 in the amount of LLZTO@ATS and O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol used; the remaining steps are the same. Specifically:

[0086] S1 is the same as in Example 1.

[0087] S2. Under a nitrogen atmosphere, 0.70 g LLZTO@ATS, 1.66 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g terephthalic diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0088] S3 is the same as in Example 1.

[0089] Comparative Example 1

[0090] The difference between Comparative Example 1 and Example 1 is that no inorganic filler was added; the remaining steps are the same. Specifically:

[0091] S1. Under a nitrogen atmosphere, 1.9 g of O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g of lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g of terephthalic diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0092] S2. After the reaction is complete, the mixture is coated onto a PP plate and dried in an oven at 60°C for 12 hours to obtain a solid electrolyte membrane.

[0093] Comparative Example 2

[0094] The difference between Comparative Example 2 and Example 1 lies in the type of crosslinking agent; the remaining steps are the same. Specifically:

[0095] S1 is the same as in Example 1.

[0096] S2. Under a nitrogen atmosphere, 0.46 g LLZTO@ATS, 1.9 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g terephthalic acid diisocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0097] S3 is the same as in Example 1.

[0098] Comparative Example 3

[0099] The difference between Comparative Example 3 and Example 1 is that LLZTO is not modified, while the remaining steps are the same. Specifically:

[0100] S1. Under a nitrogen atmosphere, 0.46 g LLZTO, 1.9 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g terephthalic diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0101] S2. Apply the solid electrolyte to a PP board and dry it overnight in a 60°C oven.

[0102] Comparative Example 4

[0103] S1. Add 10g of SiO2 to 100mL of toluene and sonicate for 30min to obtain a homogeneous suspension. Then add 1g of 3-aminopropyltrimethoxysilane and 0.2mL of deionized water to the suspension, reflux at 80℃ for 4h, cool to room temperature, centrifuge four times, and finally dry the centrifuged SiO2 in a vacuum oven at 30℃ for 24h to obtain SiO2 modified with 3-aminopropyltrimethoxysilane. The SiO2 modified with 3-aminopropyltrimethoxysilane is denoted as SiO2@ATS.

[0104] S2. Under a nitrogen atmosphere, 0.46 g SiO2@ATS, 1.9 g O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g 1,3-phenylene diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0105] S3. The solid electrolyte is coated onto a PP plate and dried in an oven at 60°C for 12 hours to obtain a solid electrolyte membrane.

[0106] Comparative Example 5

[0107] Comparative Example 5 differs from Example 1 in that it lacks a chain extender; the remaining steps are the same. Specifically:

[0108] S1 is the same as in Example 1.

[0109] S2. Under a nitrogen atmosphere, 0.46 g LLZTO@ATS and 0.8 g lithium bis(trifluoromethanesulfonyl)imide (LITFSI) were added to 10 mL of dimethylformamide (DMF). After stirring at room temperature for 30 min, a mixture was obtained. 0.37 g terephthalic diisothiocyanate was added to the mixture, and the mixture was heated and stirred at 60 °C for 24 h.

[0110] S3. The solid electrolyte is coated onto a PP plate and dried in an oven at 60°C for 12 hours to obtain a solid electrolyte membrane.

[0111] The reaction conditions for each embodiment and comparative example are summarized in Table 1.

[0112] Table 1 Summary of reaction conditions for each embodiment and comparative example

[0113]

[0114] [Performance Testing]

[0115] The testing steps are as follows:

[0116] The solid electrolyte membranes prepared in each embodiment and comparative example were used to assemble coin-type lithium metal batteries for electrochemical performance evaluation.

[0117] The battery's positive electrode uses lithium iron phosphate as the active material, C350 as the conductive agent, and polyvinylidene fluoride (PVDF) as the binder, coated onto an aluminum foil current collector; the negative electrode is a lithium metal sheet. The battery was assembled in a glove box at room temperature (25°C) and underwent constant current charge-discharge testing at a 0.2C rate (voltage window: Record the charge and discharge curves.

[0118] Initial discharge capacity: The specific capacity of the battery during its first discharge process is calculated based on the ratio of the total discharge capacity to the mass of the positive electrode active material in the first week.

[0119] Discharge capacity after 50 cycles: Record the specific discharge capacity of the battery when it completes the 50th cycle at a 0.2C rate.

[0120] Average Coulomb efficiency: The arithmetic mean of the Coulomb efficiency (discharge capacity / charge capacity × 100%) for each of the first 100 consecutive cycles.

[0121] The ionic conductivity of solid electrolytes was measured using AC impedance spectroscopy: Solid electrolytes were cut into discs, both sides of which were coated with inert electrodes (such as gold or platinum). These discs were placed in an impedance testing fixture, and an AC voltage of a specific frequency and amplitude was applied through an AC power supply at 25°C. Simultaneously, the phase difference between the current and voltage was measured. Finally, the ionic conductivity of the solid electrolyte was calculated based on the impedance model of the AC circuit.

[0122] Table 2

[0123]

[0124] Based on the analysis of Tables 1 and 2, the initial discharge capacity range measured in Examples 1 to 8 is 135.4 mAh g. -1 ~152.1mAh g -1 After 50 cycles, the discharge capacity range is 129.1 mAh g. -1 ~151.5mAh g -1 The average coulombic efficiency is 99.1%–99.8%, and the ionic conductivity ranges from 1.6 × 10⁻⁶. -4 S·cm -1 ~2.4×10 -4 S·cm -1 .

[0125] The initial discharge capacity measured in Comparative Examples 1 to 4 ranged from 120.2 mAh g. -1 ~135.1mAh g -1 After 50 cycles, the discharge capacity range is 110.4 mAh g. -1 ~120.7mAh g -1 The average coulombic efficiency is 98.6%–98.9%, and the ionic conductivity ranges from 0.8 × 10⁻⁶. -4 S·cm -1 ~1.5×10 -4 S·cm -1 Examples 1 to 8 show superior initial discharge capacity, cycle stability, coulombic efficiency, and ionic conductivity compared to Comparative Examples 1 to 4.

[0126] Compared to Example 1, Comparative Example 1 did not add inorganic fillers, and the data measured in Comparative Example 1 were significantly lower than those in Example 1. This further illustrates that the polymer structure formed by the modified inorganic filler, crosslinking agent phenyl diisothiocyanate, and chain extender improves the ion transport performance and interfacial stability of the solid electrolyte, thereby improving the electrochemical performance of the battery.

[0127] Compared to Example 1, Comparative Example 2 used terephthalic diisocyanate as the crosslinking agent, and the measured data for Comparative Example 2 were lower than those for Example 1. This further illustrates that the polymer structure formed by the crosslinking agent terephthalic diisothiocyanate, modified inorganic filler, and chain extender in Example 1 is beneficial to improving the performance of solid electrolytes.

[0128] Compared to Example 1, Comparative Example 3 used LLZTO (unmodified) as the inorganic filler, and the measured data for Comparative Example 3 were significantly lower than those for Example 1. This further illustrates that the thiourea bonds formed between the modified inorganic filler and the crosslinking agent phenyl diisothiocyanate in Example 1 enhanced the interaction between the organic / inorganic interface and improved the performance of the solid electrolyte.

[0129] Compared with Comparative Examples 1 and 3, Comparative Example 4 used SiO2@ATS as the inorganic filler, Comparative Example 1 did not use any inorganic filler, and Comparative Example 3 used LLZTO as the inorganic filler. The data measured in Comparative Example 4 were similar to those in Comparative Example 1 and lower than those in Comparative Example 3. This indicates that the performance of the solid electrolyte prepared by modifying the inorganic filler SiO2 is inferior to that prepared by other inorganic fillers.

[0130] Compared to Example 1, Comparative Example 5 does not contain a chain extender. Comparative Example 5 cannot form an organic polymer network and therefore cannot form a support film, making it impossible to conduct tests. This indicates that the chain extender plays an important role in constructing a solid electrolyte with mechanical strength and a continuous structure.

[0131] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended embodiments are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of this application.

[0132] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if these modifications and variations of this application fall within the scope of the embodiments of this application and their equivalents, this application also intends to include these modifications and variations.

Claims

1. A solid electrolyte precursor, characterized in that, The solid electrolyte precursor includes a modified inorganic filler, a chain extender, and a crosslinking agent. The crosslinking agent includes diisothiocyanate. Both the modified inorganic filler and the chain extender can react with the crosslinking agent to form thiourea structural units. Both the modified inorganic filler and the chain extender include amino groups; The modified inorganic filler is prepared by inorganic filler and silane coupling agent, and the inorganic filler includes at least one of alumina, LLZTO, LLZO, LAGP, LATP and titanium dioxide.

2. The solid electrolyte precursor as described in claim 1, characterized in that, The mass ratio of the modified inorganic filler to the crosslinking agent is 1:(0.5~2), and the mass ratio of the modified inorganic filler to the chain extender is 1:(2~9).

3. The solid electrolyte precursor as described in claim 1, characterized in that, The mass ratio of the modified inorganic filler to the chain extender and the chain extender to the crosslinking agent is (3~12):

1.

4. The solid electrolyte precursor as described in claim 1, characterized in that, The crosslinking agent includes at least one of phenyl diisothiocyanate, 1,3-phenylene diisothiocyanate, 1,6-hexanediisothiocyanate and 1,2-phenyl diisothiocyanate.

5. The solid electrolyte precursor as described in claim 1, characterized in that, The chain extender includes at least one of 1,8-octanediamine, polyoxyethylenediamine, O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol, poly(dimethylsiloxane)bis(3-aminopropyl)-terminated and adipamide.

6. The solid electrolyte precursor as described in claim 1, characterized in that, The preparation method of the modified inorganic filler includes: The inorganic filler is mixed with a first organic solvent to obtain a suspension. The silane coupling agent and water are added to the suspension. The suspension is refluxed at 40°C to 100°C for 2 to 10 hours. Then, it is cooled and centrifuged to obtain a solid. The solid is dried to obtain the modified inorganic filler. The silane coupling agent includes at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane and γ-ureopropyltriethoxysilane.

7. A solid electrolyte, characterized in that, The solid electrolyte is prepared from the solid electrolyte precursor according to any one of claims 1 to 6, wherein the preparation steps of the solid electrolyte include: Under an inert gas atmosphere, the solid electrolyte precursor, lithium salt, and a second organic solvent are mixed to obtain a mixture. The mixture is stirred and reacted at 50°C to 100°C for 10 to 48 hours. After the reaction is completed, the mixture is dried to obtain the solid electrolyte.

8. The solid electrolyte as described in claim 7, characterized in that, The process of drying the mixture to obtain the solid electrolyte includes: The mixture is coated onto a substrate and dried at 30°C to 80°C for 8 to 24 hours to obtain the solid electrolyte, which has a film structure.

9. A solid-state lithium battery, characterized in that, It includes a positive electrode, a negative electrode, and a solid electrolyte as described in claim 7 or 8.

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