A polysiloxane solid electrolyte, solid-state battery and preparation method and application thereof

Abstract

The invention provides a polysiloxane solid electrolyte, a solid-state battery, and a preparation method and application thereof. The raw materials for preparing the polysiloxane solid electrolyte include grafted polysiloxane, a polymer matrix, an inorganic filler and a lithium salt. The grafted polysiloxane obtained by copolymerizing polymethyl hydrogen siloxane, 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether effectively improves the problems of low ionic conductivity and poor mechanical properties of polysiloxane at room temperature. The polymer matrix, the inorganic filler and the lithium salt are further matched so that the obtained polysiloxane solid electrolyte has not only high flame retardancy but also excellent electrical properties and thermal stability, and can be applied to lithium ion batteries, thereby helping to improve the electrical properties of lithium ion batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid electrolytes, and in particular relates to a polysiloxane solid electrolyte, a solid battery, and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries are secondary batteries that rely mainly on the movement of lithium ions between the positive and negative electrodes to work; therefore, electrolytes that assist the movement of lithium ions have become a key component of lithium-ion batteries, and are directly related to the battery's cycle life, safety, capacity and other performance. At present, the most widely used electrolytes on the market are still organic liquid electrolytes. Organic liquid electrolytes are not only prone to problems such as organic solvent leakage, combustion and explosion, which lead to major safety hazards when lithium ion points are used, but most organic liquid electrolytes are extremely toxic. Therefore, using non-flammable solid electrolytes to replace organic liquid electrolytes has become a hot topic in current research and is also one of the important technical directions for the next generation of batteries.

[0003] At present, the solid electrolytes studied mainly include three categories: inorganic solid electrolytes, polymer solid electrolytes and organic / inorganic composite solid electrolytes. Among them, inorganic solid electrolytes have the advantages of high mechanical strength, wide electrochemical window, and high room temperature ionic conductivity, but poor interface contact with electrodes and high preparation cost; organic solid electrolytes have good flexibility, good interface contact with electrodes, mature preparation process, and low cost, but their ionic conductivity is low and it is difficult to meet the commercial application of lithium-ion batteries. Organic / inorganic composite solid electrolytes can simultaneously combine the advantages of organic and inorganic solid electrolytes, and have become solid electrolytes with great application prospects.

[0004] Among many polymer matrices, polysiloxane is a typical semi-inorganic polymer electrolyte with -Si-O- repeating units as the main chain and organic groups directly connected to Si atoms. Its characteristics are as follows: (1) It has excellent flexibility, which is conducive to segment movement, thereby accelerating ion conduction; (2) It has a low glass transition temperature and is highly elastic at room temperature, which is conducive to reducing the interface impedance between the electrode; (3) It has excellent high and low temperature resistance and can be used at -60℃ to 255℃; (4) It has good thermal stability and electrochemical stability, and the electrochemical stability window can reach above 4.5V. CN109256582A discloses a composite solid electrolyte for an all-solid-state lithium ion battery, which comprises an inorganic electrolyte layer and two organic electrolyte layers attached to the two surfaces of the inorganic electrolyte layer, characterized in that the organic electrolyte layer comprises a lithium salt and an organic electrolyte, and the inorganic electrolyte layer is formed by an inorganic electrolyte doped with a rare metal. The battery containing the composite solid electrolyte of the present invention has high energy density and high safety. However, the use of conventional polysiloxane at room temperature will lead to problems such as low ionic conductivity and poor mechanical properties, which will affect the electrical performance of lithium-ion batteries.

[0005] Therefore, in order to solve the above technical problems, developing a polysiloxane solid electrolyte with high ionic conductivity has become a key issue in current research. Summary of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a polysiloxane solid electrolyte, a solid-state battery, and a preparation method and application thereof. The polysiloxane solid electrolyte is prepared by copolymerizing a polysiloxane monomer with 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether to obtain a grafted polysiloxane, which is then combined with a polymer matrix, an inorganic filler and a lithium salt to obtain a polysiloxane solid electrolyte with excellent thermal stability, flame retardancy and electrochemical properties.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a polysiloxane solid electrolyte, wherein the raw materials for preparing the polysiloxane solid electrolyte include grafted polysiloxane, a polymer matrix, an inorganic filler and a lithium salt;

[0009] The raw materials for preparing the grafted polysiloxane include polymethyl hydrogen siloxane, 1,2-epoxy-4-vinyl cyclohexane and isopentanol polyoxyethylene ether.

[0010] The raw materials for preparing the polysiloxane solid electrolyte provided by the present invention include grafted polysiloxane. The grafted polysiloxane obtained by copolymerizing polymethyl hydrogen siloxane, 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether effectively improves the problems of low ionic conductivity and poor mechanical properties of polysiloxane at room temperature. The polysiloxane solid electrolyte obtained by combining a polymer matrix, an inorganic filler and a lithium salt not only has high flame retardancy, but also has excellent electrical properties and thermal stability. It can be applied to lithium ion batteries, which helps to improve the electrical properties of lithium ion batteries.

[0011] Preferably, the grafted polysiloxane comprises the following general formula:

[0012]

[0013] Wherein, x is selected from 6 to 10, such as 7, 8 or 9;

[0014] Y is selected from 12 to 20, such as 13, 14, 15, 16, 17, 18 or 19;

[0015] z is selected from 6 to 10, such as 7, 8 or 9.

[0016] Preferably, the molar ratio of the total molar amount of 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether to the hydrogen in the main chain of polymethylhydrogensiloxane is 1:(1-2), for example, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8 or 1:1.9, etc.

[0017] Preferably, the molar ratio of the 1,2-epoxy-4-vinylcyclohexane to the isopentenol polyoxyethylene ether is 1:(0.5-2), for example, 1:0.7, 1:0.9, 1:1.1, 1:1.3, 1:1.5, 1:1.7 or 1:1.9.

[0018] Preferably, the mass ratio of the polymer matrix to the grafted polysiloxane is 1:(0.11-9), for example, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8, etc.

[0019] Preferably, the polymer matrix includes any one or a combination of at least two of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate or polyacrylonitrile.

[0020] Preferably, the mass ratio of the total mass of the polymer matrix and the grafted polysiloxane to the inorganic filler is 1:(0.1-0.5), for example, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4 or 1:0.45, etc.

[0021] Preferably, the inorganic filler comprises SiO 2 、Al 2 O 3 , LLZTO, LLTO, LATP, LGPS or LPS, or a combination of at least two of them.

[0022] Preferably, the mass ratio of the total mass of the polymer matrix and the grafted polysiloxane to the lithium salt is 1:(0.1-0.35), for example, 1:0.12, 1:0.14, 1:0.16, 1:0.18, 1:0.2, 1:0.22, 1:0.24, 1:0.26, 1:0.28, 1:0.3, 1:0.32 or 1:0.34, etc.

[0023] Preferably, the lithium salt includes LiSCN, LiN(CN) 2 、Li(CF 3 SO 2 ) 3 C. LiC 4 F 9 SO 3 、LiN(SO 2 CF 2 CF 3 ) 2 、LiB(C 2 O4) 2 , C 4 BLiO 8 、LiBOB、LiBF 4 , LiBF 3 (C 2 F 5 )、LiDFOB、C 2 BF 2 LiO 4 、LIODFB、LiTFSI、LiN(SO 2 CF 3 ) 2 、LiFSI,LiN(SO 2 F) 2 、LiCF 3 SO 3 、LiAsF6、LiSbF 6 or LiClO 4 Any one or a combination of at least two of the following.

[0024] In a second aspect, the present invention provides a method for preparing the polysiloxane solid electrolyte as described in the first aspect, the preparation method comprising the following steps:

[0025] (1) reacting polymethyl hydrogen siloxane, 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether to obtain a grafted polysiloxane;

[0026] (2) The grafted polysiloxane obtained in step (1), an inorganic filler, a polymer matrix and a lithium salt are mixed to obtain the polysiloxane solid electrolyte.

[0027] Preferably, the reaction in step (1) is carried out in toluene solvent.

[0028] Preferably, the reaction in step (1) is carried out under the protection of an inert gas, more preferably under the protection of nitrogen.

[0029] Preferably, the reaction temperature in step (1) is 90-110°C, for example, 92°C, 94°C, 96°C, 98°C, 100°C, 102°C, 104°C, 106°C or 108°C.

[0030] Preferably, a catalyst is also added in the reaction of step (1).

[0031] Preferably, the mass percentage of the catalyst in all the reaction raw materials in step (1) is 1-5%, for example, 1.5%, 2%, 2.5%, 3%, 3.5%, 4% or 4.5%.

[0032] Preferably, the catalyst comprises chloroplatinic acid and / or a Custer catalyst.

[0033] Preferably, the mixing in step (2) specifically comprises: dispersing an inorganic filler in an organic solvent under ultrasonic conditions, adding a polymer matrix and the grafted polysiloxane obtained in step (1) to mix, then adding a lithium salt to mix, and drying to obtain the polysiloxane solid electrolyte;

[0034] Preferably, the organic solvent includes any one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide or acetonitrile, or a combination of at least two thereof.

[0035] Preferably, the dispersion time of the inorganic filler in the organic solvent is 5 to 30 min, for example, 7 min, 9 min, 11 min, 13 min, 15 min, 17 min, 19 min, 21 min, 23 min, 25 min, 27 min or 29 min.

[0036] Preferably, the time for mixing the polymer matrix and the grafted polysiloxane obtained in step (1) is 20 to 40 minutes, for example, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes or 38 minutes.

[0037] Preferably, the time for adding the lithium salt for mixing is 0.5 to 1.5 h, for example, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, 1.1 h, 1.2 h, 1.3 h or 1.4 h.

[0038] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0039] (1) reacting polymethyl hydrogen siloxane, 1,2-epoxy-4-vinylcyclohexane, isopentanol polyoxyethylene ether and optionally a catalyst in a toluene solvent at 90 to 110° C. under nitrogen protection to obtain a grafted polysiloxane;

[0040] (2) dispersing the inorganic filler in an organic solvent under ultrasonic conditions for 5 to 30 minutes, adding the polymer matrix and the grafted polysiloxane obtained in step (1) and mixing for 20 to 40 minutes, adding the inorganic filler and the lithium salt and mixing for 0.5 to 1.5 hours to obtain the polysiloxane solid electrolyte.

[0041] In a third aspect, the present invention provides a solid-state battery, comprising a positive electrode sheet, a negative electrode sheet, an aluminum-plastic film, and the polysiloxane solid electrolyte as described in the first aspect.

[0042] In a fourth aspect, the present invention provides a method for preparing a solid-state battery as described in the third aspect, the preparation method comprising the following steps:

[0043] (A1) coating a polysiloxane solid electrolyte on the surface of a positive electrode sheet to obtain a composite positive electrode; coating a polysiloxane solid electrolyte on the surface of a negative electrode sheet to obtain a composite negative electrode;

[0044] (A2) stacking the composite positive electrode and the composite negative electrode obtained in step (A1), and encapsulating them with an aluminum-plastic film to obtain the solid-state battery.

[0045] Preferably, the positive electrode material in the positive electrode sheet in step (A1) includes any one of lithium cobalt oxide, ternary material, lithium iron phosphate, lithium-rich manganese-based material or spinel lithium manganese oxide, or a combination of at least two thereof.

[0046] Preferably, the negative electrode material in the negative electrode sheet in step (A1) includes graphite, amorphous carbon, lithium titanate, SiO x Any one of or a combination of at least two of the Sn-based composite materials.

[0047] Preferably, step (A1) further includes a drying step after coating on the surface of the positive electrode sheet and coating on the surface of the negative electrode sheet.

[0048] Preferably, the drying time is 8 to 12 hours, for example, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours or 11.5 hours.

[0049] Preferably, the drying temperature is 50-70°C, for example, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C or 68°C.

[0050] Preferably, after the drying is completed, the thickness of the positive electrode sheet surface coating and the negative electrode sheet surface coating is independently 20 to 40 μm, for example, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm, 36 μm or 38 μm.

[0051] Preferably, after the packaging in step (A2), the steps of vacuuming, heat sealing, hot pressing and cold pressing are also included.

[0052] Preferably, the heat sealing temperature is 180-200°C, for example, 182°C, 184°C, 186°C, 188°C, 190°C, 192°C, 194°C, 196°C or 198°C.

[0053] Preferably, the heat sealing pressure is 0.1-1 MPa, for example, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa or 0.9 MPa.

[0054] Preferably, the heat sealing time is 5 to 10 s, for example, 5.5 s, 6 s, 6.5 s, 7 s, 7.5 s, 8 s, 8.5 s, 9 s or 9.5 s.

[0055] Preferably, the temperature of the hot pressing is 80-100°C, for example, 82°C, 84°C, 86°C, 88°C, 100°C, 102°C, 104°C, 106°C or 108°C.

[0056] Preferably, the pressure of the hot pressing and the cold pressing is independently 0.1-0.5 MPa, such as 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa or 0.45 MPa.

[0057] Preferably, the time of the hot pressing and the cold pressing is independently 20 to 300 s, for example, 50 s, 80 s, 110 s, 140 s, 170 s, 200 s, 230 s, 260 s or 290 s.

[0058] Preferably, the temperature of the cold pressing is 20-30°C, for example, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C or 29°C.

[0059] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0060] (A1) coating a polysiloxane solid electrolyte on the surface of the positive electrode sheet, drying at 50-70° C. for 8-12 hours, and obtaining a composite positive electrode having a surface coating thickness of 20-40 μm; coating a polysiloxane solid electrolyte on the surface of the negative electrode sheet, drying at 50-70° C. for 8-12 hours, and obtaining a composite negative electrode having a surface coating thickness of 20-40 μm;

[0061] (A2) The composite positive electrode and the composite negative electrode obtained in step (A1) are stacked, packaged with an aluminum-plastic film, heat-sealed for 5 to 10 seconds under vacuum, 180 to 200° C. and 0.1 to 1 MPa, hot-pressed for 20 to 300 seconds under 80 to 100° C. and 0.1 to 0.5 MPa, and cold-pressed for 20 to 300 seconds under 20 to 30° C. and 0.1 to 0.5 MPa, to obtain the solid-state battery.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] The polysiloxane solid electrolyte provided by the present invention comprises a combination of grafted polysiloxane, a polymer matrix, an inorganic filler and a lithium salt, wherein the raw materials for preparing the grafted polysiloxane comprise a combination of polymethyl hydrogen siloxane, 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether; the grafted polysiloxane obtained by copolymerizing polymethyl hydrogen siloxane, 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether effectively improves the problems of low ionic conductivity and poor mechanical properties of polysiloxane at room temperature; the polysiloxane solid electrolyte obtained by combining the polymer matrix, the inorganic filler and the lithium salt not only has high flame retardancy, but also has excellent electrical properties and thermal stability, and can be applied to lithium ion batteries, thus helping to improve the electrical properties of lithium ion batteries. DETAILED DESCRIPTION

[0064] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0065] Example 1

[0066] A polysiloxane solid electrolyte, the preparation raw materials of which are grafted polysiloxane, polyethylene oxide, SiO 2 and LiTFSI combination;

[0067] The mass ratio of polyethylene oxide to grafted polysiloxane is 1:5, and the total mass of polyethylene oxide and grafted polysiloxane is 1:5. 2The mass ratio of is 1:0.25, and the mass ratio of the total mass of polyethylene oxide and grafted polysiloxane to LiTFSI is 1:0.2;

[0068] The preparation method of the polysiloxane solid electrolyte provided in this embodiment comprises the following steps:

[0069] (1) at 100° C. and under nitrogen protection, polymethyl hydrogen siloxane (Aladdin, 9004-73-3), 1,2-epoxy-4-vinylcyclohexane, isopentanol polyoxyethylene ether and chloroplatinic acid are reacted in toluene solvent for 24 hours (the molar ratio of the total molar amount of 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether to the hydrogen in the main chain of polymethyl hydrogen siloxane is 1:1.5; the molar ratio of 1,2-epoxy-4-vinylcyclohexane to isopentanol polyoxyethylene ether is 1:1; the mass percentage of the catalyst in all the reaction raw materials in step (1) is 2.5%;) to obtain a grafted polysiloxane;

[0070] (2) SiO 2 Disperse in N-methylpyrrolidone for 5 to 30 minutes, add polyethylene oxide (Aladdin, 68441-17-8) and the grafted polysiloxane obtained in step (1) and mix in a planetary mixer for 30 minutes, add LiTFSI and mix in a planetary mixer for 1 hour to obtain the polysiloxane solid electrolyte.

[0071] Example 2

[0072] A polysiloxane solid electrolyte, the preparation raw materials of which are grafted polysiloxane, polyvinylidene fluoride, Al 2 O 3 and LiN(CN) 2 combination of;

[0073] The mass ratio of polyvinylidene fluoride to grafted polysiloxane is 1:9, and the total mass of polyvinylidene fluoride and grafted polysiloxane is 1:9. 2 O 3 The mass ratio of polyvinylidene fluoride and grafted polysiloxane is 1:0.5, and the total mass of LiN(CN) 2 The mass ratio is 1:0.35;

[0074] The structural formula of the grafted polysiloxane is: The method for preparing the polysiloxane solid electrolyte provided in this embodiment comprises the following steps:

[0075] (1) at 100° C. and under nitrogen protection, polymethyl hydrogen siloxane (Aladdin, 9004-73-3), 1,2-epoxy-4-vinylcyclohexane, isopentanol polyoxyethylene ether and chloroplatinic acid are reacted in toluene solvent for 24 hours (the molar ratio of the total molar amount of 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether to the hydrogen in the main chain of polymethyl hydrogen siloxane is 1:2; the molar ratio of 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether is 1:1; the mass percentage of the catalyst in all the reaction raw materials in step (1) is 5%) to obtain a grafted polysiloxane;

[0076] (2) Al 2 O 3 Disperse in N-methylpyrrolidone for 5 to 30 minutes, add polyvinylidene fluoride (Arkema, HSV761) and the grafted polysiloxane obtained in step (1) and mix in a planetary mixer for 30 minutes, add LiN(CN) 2 The mixture was mixed in a planetary mixer for 1 hour to obtain the polysiloxane solid electrolyte.

[0077] Example 3

[0078] A polysiloxane solid electrolyte, wherein the raw materials for preparation are grafted polysiloxane, polyvinylidene fluoride-hexafluoropropylene, LLZTO and Li(CF 3 SO 2 ) 3 Combination of C;

[0079] The mass ratio of polyvinylidene fluoride-hexafluoropropylene to grafted polysiloxane is 1:0.11, the mass ratio of the total mass of polyvinylidene fluoride-hexafluoropropylene and grafted polysiloxane to LLZTO is 1:0.1, and the total mass of polyvinylidene fluoride-hexafluoropropylene and grafted polysiloxane to Li(CF 3 SO 2 ) 3 The mass ratio of C is 1:0.1;

[0080] The preparation method of the polysiloxane solid electrolyte provided in this embodiment comprises the following steps:

[0081] (1) at 100° C. and under nitrogen protection, polymethyl hydrogen siloxane (Aladdin, 9004-73-3), 1,2-epoxy-4-vinylcyclohexane, isopentanol polyoxyethylene ether and chloroplatinic acid are reacted in toluene solvent for 24 hours (the molar ratio of the total molar amount of 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether to the hydrogen in the main chain of polymethyl hydrogen siloxane is 1:1; the molar ratio of 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether is 1:1; the mass percentage of the catalyst in all the reaction raw materials in step (1) is 1%) to obtain a grafted polysiloxane;

[0082] (2) LLZTO was dispersed in N-methylpyrrolidone under ultrasonic conditions for 5 to 30 minutes, polyvinylidene fluoride-hexafluoropropylene (Solvay, 21510) and the grafted polysiloxane obtained in step (1) were added and mixed in a planetary mixer for 30 minutes, and Li(CF 3 SO 2 ) 3 C was mixed in a planetary mixer for 1 hour to obtain the polysiloxane solid electrolyte.

[0083] Comparative Example 1

[0084] A polysiloxane solid electrolyte, the preparation raw materials of which are grafted polysiloxane, polyethylene oxide, SiO 2 and LiTFSI combination;

[0085] The mass ratio of polyethylene oxide to grafted polysiloxane is 1:5, and the total mass of polyethylene oxide and grafted polysiloxane is 1:5. 2 The mass ratio of is 1:0.25, and the mass ratio of the total mass of polyethylene oxide and grafted polysiloxane to LiTFSI is 1:0.2;

[0086] The preparation method of the polysiloxane solid electrolyte provided in this comparative example comprises the following steps:

[0087] (1) at 100° C. and under nitrogen protection, polymethylhydrogensiloxane (Aladdin, 9004-73-3), 1,2-epoxy-4-vinylcyclohexane and chloroplatinic acid are reacted in a toluene solvent for 24 hours (the molar ratio of hydrogen in the main chain of 1,2-epoxy-4-vinylcyclohexane to polymethylhydrogensiloxane is 1:1.5; the mass percentage of the catalyst in all the reaction raw materials in step (1) is 2.5%) to obtain a grafted polysiloxane;

[0088] (2) SiO 2Disperse in N-methylpyrrolidone for 5 to 30 minutes, add polyethylene oxide (Aladdin, 68441-17-8) and the grafted polysiloxane obtained in step (1) and mix in a planetary mixer for 30 minutes, add LiTFSI and mix in a planetary mixer for 1 hour to obtain the polysiloxane solid electrolyte.

[0089] Comparative Example 2

[0090] A polysiloxane solid electrolyte, the preparation raw materials of which are grafted polysiloxane, polyethylene oxide, SiO 2 and LiTFSI combination;

[0091] The mass ratio of polyethylene oxide to grafted polysiloxane is 1:5, and the total mass of polyethylene oxide and grafted polysiloxane is 1:5. 2 The mass ratio of is 1:0.25, and the mass ratio of the total mass of polyethylene oxide and grafted polysiloxane to LiTFSI is 1:0.2;

[0092] The preparation method of the polysiloxane solid electrolyte provided in this comparative example comprises the following steps:

[0093] (1) at 100° C. and under nitrogen protection, polymethyl hydrogen siloxane (Aladdin, 9004-73-3), isopentanol polyoxyethylene ether and chloroplatinic acid are reacted in toluene solvent for 24 hours (the molar ratio of isopentanol polyoxyethylene ether to hydrogen in the main chain of polymethyl hydrogen siloxane is 1:1.5; the mass percentage of the catalyst in all the reaction raw materials in step (1) is 2.5%) to obtain a grafted polysiloxane;

[0094] (2) SiO 2 Disperse in N-methylpyrrolidone for 5 to 30 minutes, add polyethylene oxide (Aladdin, 68441-17-8) and the grafted polysiloxane obtained in step (1) and mix in a planetary mixer for 30 minutes, add LiTFSI and mix in a planetary mixer for 1 hour to obtain the polysiloxane solid electrolyte.

[0095] Comparative Example 3

[0096] A polysiloxane solid electrolyte, the preparation raw materials of which are polysiloxane, polyethylene oxide, SiO 2 and LiTFSI combination;

[0097] The mass ratio of polyethylene oxide to polysiloxane is 1:5, and the total mass of polyethylene oxide and polysiloxane is 1:5. 2 The mass ratio of is 1:0.25, and the mass ratio of the total mass of polyethylene oxide and polysiloxane to LiTFSI is 1:0.2;

[0098] The preparation method of the polysiloxane solid electrolyte provided in this comparative example comprises: 2 Disperse in N-methylpyrrolidone for 5 to 30 minutes, add polyethylene oxide (Aladdin, 68441-17-8) and polysiloxane (Aladdin, 9004-73-3) and mix in a planetary mixer for 30 minutes, add LiTFSI and mix in a planetary mixer for 1 hour to obtain the polysiloxane solid electrolyte.

[0099] Performance Test:

[0100] (1) Ionic conductivity test: A symmetrical battery with stainless steel sheets is made, with the negative electrode shell opening facing upwards. The spring sheet and the stainless steel gasket are placed in the middle of the negative electrode shell respectively. The solid electrolyte membrane is clamped to cover the stainless steel gasket, and another stainless steel sheet is clamped to cover the polysiloxane solid electrolyte membrane, and they are strictly aligned. Finally, the positive electrode shell is clamped to cover it, and then the button battery is placed on the button battery sealing mold with the negative electrode facing upwards with tweezers. The pressure is adjusted to 10MPa, and the button battery is assembled after holding the pressure for 5s. The EIS test is performed using an electrochemical workstation with a frequency range of 106-1Hz and an amplitude of 5mV. The conductivity of the electrolyte membrane ions is calculated using the formula ionic conductivity σ=L / (R×A), where L is the thickness of the electrolyte membrane, A is the effective area of ​​the electrolyte membrane, and R is the bulk resistance of the electrolyte membrane. The resistance value at the intersection of the EIS curve and the real axis is taken as the ionic conductivity.

[0101] (2) Cycle performance test: A lithium-ion solid-state battery was prepared, and a polysiloxane solid electrolyte was coated on the surface of a positive electrode sheet (the positive electrode sheet comprises: 97 wt% NCM ternary material, 1 wt% carbon black, 1 wt% PVDF and an aluminum foil with a thickness of 12 μm), and dried at 60°C for 10 h to obtain a composite positive electrode with a coating thickness of 30 μm; a polysiloxane solid electrolyte was coated on the surface of a negative electrode sheet (the negative electrode sheet comprises: 80 wt% graphite, 15 wt% silicon-oxygen active material, 2 wt% carbon nanotubes and carbon black, 3 wt% PAA and a copper foil with a thickness of 8 μm), and dried at 60°C for 10 h, and obtain a composite negative electrode with a coating thickness of 30 μm; the obtained composite positive electrode and the composite negative electrode are superimposed to make the capacity of the obtained soft-pack solid-state battery be 1200 mA / h, and the battery is packaged with an aluminum-plastic film, vacuumed, heat-sealed at 190°C and 0.5 MPa for 7s, hot-pressed at 90°C and 0.25 MPa for 150s, and cold-pressed at 25°C and 0.25 MPa for 150s to obtain a lithium-ion solid-state battery; the obtained lithium-ion solid-state battery is tested by a blue electric tester in an environment of 25°C, and the number of cycles when the capacity of the solid-state battery reaches 80% under 0.2C conditions is the cycle performance.

[0102] The polysiloxane solid electrolytes obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were tested according to the above test method. The test results are shown in Table 1:

[0103] Table 1

[0104] Ionic conductivity (S / cm) Cycle performance (times) Example 1 <![CDATA[2.38×10 -4 ]]> 79 Example 2 <![CDATA[1.98×10 -4 ]]> 75 Example 3 <![CDATA[1.86×10 -4 ]]> 72 Comparative Example 1 <![CDATA[1.46×10 -4 ]]> 67 Comparative Example 2 <![CDATA[1.37×10 -4 ]]> 69 Comparative Example 3 <![CDATA[6.95×10 -5 ]]> 63

[0105] According to the data in Table 1, we can see that:

[0106] The ionic conductivity of the polysiloxane solid electrolyte provided in Examples 1 to 3 is 1.86×10 -4 ~2.38×10 - 4 S / cm, and the number of cycles of the prepared lithium-ion solid-state battery at 25°C is 72 to 79 times.

[0107] By comparing Example 1 and Comparative Examples 1 to 2, it can be found that the ionic conductivity of the polysiloxane solid electrolyte obtained by not adding isopentanol polyoxyethylene ether when preparing the grafted polysiloxane (Comparative Example 1) and not adding 1,2-epoxy-4-vinylcyclohexane when preparing the grafted polysiloxane (Comparative Example 2) is greatly reduced, thereby reducing the cycle performance of the obtained solid-state battery.

[0108] By comparing Example 1 and Comparative Example 3, it can be found that the ionic conductivity of the polysiloxane solid electrolyte obtained without grafting of polysiloxane is also reduced, thereby reducing the cycle performance of the obtained solid-state battery.

[0109] The applicant declares that the present invention illustrates a polysiloxane solid electrolyte, a solid battery and its preparation method and application through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polysiloxane solid electrolyte, It is characterized in that The raw materials for preparing the polysiloxane solid electrolyte include grafted polysiloxane, polymer matrix, inorganic filler and lithium salt; The raw materials for preparing the grafted polysiloxane include polymethyl hydrogen siloxane, 1,2-epoxy-4-vinyl cyclohexane and isopentanol polyoxyethylene ether; The grafted polysiloxane comprises the following general formula: Among them, x is selected from 6 to 10, y is selected from 12 to 20, z is selected from 6 to 10, and n is selected from 5 to 17.

2. The polysiloxane solid electrolyte according to claim 1, It is characterized in that The molar ratio of the total molar amount of the 1,2-epoxy-4-vinylcyclohexane and the isopentenol polyoxyethylene ether to the hydrogen in the main chain of the polymethylhydrogensiloxane is 1:(1-2).

3. The polysiloxane solid electrolyte according to claim 1, It is characterized in that The molar ratio of the 1,2-epoxy-4-vinylcyclohexane to the isopentenol polyoxyethylene ether is 1:(0.5-2).

4. The polysiloxane solid electrolyte according to claim 1, It is characterized in that The mass ratio of the polymer matrix to the grafted polysiloxane is 1:(0.11-9).

5. The polysiloxane solid electrolyte according to claim 1, It is characterized in that The polymer matrix includes any one or a combination of at least two of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate or polyacrylonitrile.

6. The polysiloxane solid electrolyte according to claim 1, It is characterized in that The mass ratio of the total mass of the polymer matrix and the grafted polysiloxane to the inorganic filler is 1:(0.1-0.5).

7. The polysiloxane solid electrolyte according to claim 1, It is characterized in that The inorganic filler includes SiO 2 、Al 2 O 3 , LLZTO, LLTO, LATP, LGPS or LPS, or a combination of at least two of them.

8. The polysiloxane solid electrolyte according to claim 1, It is characterized in that The mass ratio of the total mass of the polymer matrix and the grafted polysiloxane to the lithium salt is 1:(0.1-0.35).

9. The polysiloxane solid electrolyte according to claim 1, It is characterized in that The lithium salt includes LiSCN, LiN(CN) 2 、Li(CF 3 SO 2 ) 3 C. LiC 4 F 9 SO 3 、LiN(SO 2 CF 2 CF 3 ) 2 、LiB(C 2 O4) 2 , C 4 BLiO 8 、LiBOB、LiBF 4 , LiBF 3 (C 2 F 5 )、LiDFOB、C 2 BF 2 LiO 4 、LIODFB、LiTFSI、LiN(SO 2 CF 3 ) 2 、LiFSI,LiN(SO 2 F) 2 、LiCF 3 SO 3 、LiAsF6、LiSbF 6 or LiClO 4 Any one or a combination of at least two of the following.

10. A method for preparing the polysiloxane solid electrolyte according to any one of claims 1 to 9, It is characterized in that The preparation method comprises the following steps: (1) reacting polymethyl hydrogen siloxane, 1,2-epoxy-4-vinylcyclohexane and isopentanol polyoxyethylene ether to obtain a grafted polysiloxane; (2) The grafted polysiloxane obtained in step (1), an inorganic filler, a polymer matrix and a lithium salt are mixed to form the polysiloxane solid electrolyte.

11. The preparation method according to claim 10, It is characterized in that The reaction in step (1) is carried out in toluene solvent.

12. The preparation method according to claim 10, It is characterized in that The reaction in step (1) is carried out under the protection of an inert gas.

13. The preparation method according to claim 12, It is characterized in that The reaction in step (1) is carried out under nitrogen protection.

14. The preparation method according to claim 10, It is characterized in that The reaction temperature in step (1) is 90-110°C.

15. The preparation method according to claim 10, It is characterized in that A catalyst is also added in the reaction of step (1).

16. The preparation method according to claim 15, It is characterized in that The mass percentage of the catalyst in all the reaction raw materials in step (1) is 1-5%.

17. The preparation method according to claim 15, It is characterized in that The catalyst includes chloroplatinic acid and / or a Custer catalyst.

18. The preparation method according to claim 10, It is characterized in that The mixing in step (2) specifically includes: dispersing the inorganic filler in an organic solvent under ultrasonic conditions, adding a polymer matrix and the grafted polysiloxane obtained in step (1) to mix, and then adding a lithium salt to mix to obtain the polysiloxane solid electrolyte.

19. The preparation method according to claim 18, It is characterized in that The organic solvent includes any one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide or acetonitrile, or a combination of at least two thereof.

20. The preparation method according to claim 18, It is characterized in that The inorganic filler is dispersed in the organic solvent for 5 to 30 minutes.

21. The preparation method according to claim 10, It is characterized in that The time for mixing the polymer matrix and the grafted polysiloxane obtained in step (1) is 20 to 40 minutes.

22. The preparation method according to claim 10, It is characterized in that The time for adding the lithium salt and mixing is 0.5 to 1.5 hours.

23. A solid-state battery, It is characterized in that The solid-state battery comprises a positive electrode sheet, a negative electrode sheet, an aluminum-plastic film and a polysiloxane solid electrolyte as described in any one of claims 1 to 9.

24. A method for preparing a solid-state battery as claimed in claim 23, It is characterized in that The preparation method comprises the following steps: (A1) coating a polysiloxane solid electrolyte on the surface of a positive electrode sheet to obtain a composite positive electrode; coating a polysiloxane solid electrolyte on the surface of a negative electrode sheet to obtain a composite negative electrode; (A2) stacking the composite positive electrode and the composite negative electrode obtained in step (A1), and encapsulating them with an aluminum-plastic film to obtain the solid-state battery.

25. The preparation method according to claim 24, It is characterized in that The positive electrode material in the positive electrode sheet in step (A1) includes any one of lithium cobalt oxide, ternary material, lithium iron phosphate, lithium-rich manganese-based material or spinel lithium manganese oxide, or a combination of at least two thereof.

26. The preparation method according to claim 24, It is characterized in that The negative electrode material in the negative electrode sheet of step (A1) includes graphite, amorphous carbon, lithium titanate, SiO x Any one of or a combination of at least two of the Sn-based composite materials.

27. The preparation method according to claim 24, It is characterized in that The step (A1) further comprises a drying step after coating on the surface of the positive electrode sheet and coating on the surface of the negative electrode sheet.

28. The preparation method according to claim 27, It is characterized in that The drying time is 8 to 12 hours.

29. The preparation method according to claim 27, It is characterized in that The drying temperature is 50-70°C.

30. The preparation method according to claim 27, It is characterized in that After the drying is completed, the thickness of the positive electrode sheet surface coating and the negative electrode sheet surface coating are independently 20 to 40 μm.

31. The preparation method according to claim 24, It is characterized in that After the packaging in step (A2) is completed, the steps of vacuuming, heat sealing, hot pressing and cold pressing are also included.

32. The preparation method according to claim 31, It is characterized in that The heat sealing temperature is 180-200°C.

33. The preparation method according to claim 31, It is characterized in that The heat sealing pressure is 0.1-1 MPa.

34. The preparation method according to claim 31, It is characterized in that The heat sealing time is 5 to 10 seconds.

35. The preparation method according to claim 31, It is characterized in that The temperature of the hot pressing is 80-100°C.

36. The preparation method according to claim 31, It is characterized in that The pressures of the hot pressing and the cold pressing are each independently 0.1 to 0.5 MPa.

37. The preparation method according to claim 31, It is characterized in that The time of the hot pressing and the cold pressing are independently 20 to 300 seconds.

38. The preparation method according to claim 31, It is characterized in that The temperature of the cold pressing is 20-30°C.

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