Solid electrolyte materials and batteries

Abstract

This invention provides a solid electrolyte material with excellent lithium ion transportability. [Solution] A solid electrolyte material comprising a Li salt having a fluorine-containing anion, an inorganic filler, and a polymer, wherein the inorganic filler is surface-modified with a fluorinated alkyl.

Description

[Technical Field]

[0001] This disclosure relates to solid electrolyte materials and batteries. [Background technology]

[0002] Various technologies have been proposed for solid electrolyte materials, such as those disclosed in Patent Document 1. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-081934 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Patent Document 1 discloses a solid electrolyte containing an ionic liquid, a compound having the function of encapsulating anions, an electrolyte salt, and an inorganic filler (inorganic compound particles) in order to provide a solid electrolyte with a high lithium ion transportability, excellent safety and durability, and excellent cycleability. Patent Document 1 states that the compound having the function of encapsulating anions coordinates with the anions of the electrolyte salt, thereby exhibiting an effect of improving the lithium ion transportability. In Patent Document 1, these components are mixed to prepare a solid electrolyte, making it difficult to uniformly disperse the compound having the function of encapsulating anions with the inorganic filler. As a result, there is a problem in that it is difficult to obtain an improvement in lithium ion transport fraction.

[0005] This disclosure is made in view of the above circumstances and primarily aims to provide a solid electrolyte material with excellent lithium ion transportability. [Means for solving the problem]

[0006] In other words, this disclosure includes the following aspects: <1> A solid electrolyte material, The solid electrolyte material comprises a Li salt having a fluorine-containing anion, an inorganic filler, and a polymer. The inorganic filler is a solid electrolyte material whose surface is modified with a fluorinated alkyl group.

[0007] <2> The solid electrolyte material further comprises succinonitrile, <1> The solid electrolyte material described above.

[0008] <3> The inorganic filler comprises at least one selected from the group consisting of SiO2, TiO2, ZrO2, and MgO. The fluorinated alkyl group comprises at least one of the following: a 1H,1H,2H,2H-tridecafluoro-n-octyl group and a 1H,1H,2H,2H-heptadecafluorodecyl group. <1> or <2> The solid electrolyte material described above.

[0009] <4> The Li salt comprises at least one selected from the group consisting of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium fluorosulfonyl(trifluoromethanesulfonyl)imide (LiFTFSI), LiPF6, LiBF4, and LiCF3SO3 (LiTfO). <1> ~ <3> A solid electrolyte material as described in any one of the following.

[0010] <5> A battery having a positive electrode layer, a negative electrode layer, and an electrolyte layer, The electrolyte layer includes a solid electrolyte, The solid electrolyte is <1> ~ <4> A battery, which is a solid electrolyte material as described in any one of the following. [Effects of the Invention]

[0011] According to the present disclosure, a solid electrolyte material excellent in lithium ion transport rate can be obtained.

Brief Description of Drawings

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a battery in the present disclosure.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments according to the present disclosure will be described. In addition, matters other than those specifically mentioned in this specification and necessary for the implementation of the present disclosure (for example, general configurations and manufacturing processes of solid electrolyte materials that do not characterize the present disclosure) can be grasped as design matters of those skilled in the art based on the prior art in the relevant field. The present disclosure can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. In the present disclosure, unless otherwise specified, the average particle size of the particles is the value of the median diameter (D50), which is the particle diameter at the integrated value of 50% in the volume-based particle size distribution measured by laser diffraction / scattering particle size distribution measurement.

[0014] A. Solid Electrolyte Material In the present disclosure, there is provided a solid electrolyte material including a Li salt having an anion containing fluorine, an inorganic filler, and a polymer, wherein the inorganic filler is surface-modified with a fluorinated alkyl.

[0015] In a solid electrolyte material including a Li salt having an anion containing fluorine (hereinafter sometimes referred to as an F-containing anion), an inorganic filler, and a polymer, since both lithium ions (cations) and F-containing anions move, the lithium ion transport rate becomes low. Therefore, in the solid electrolyte material of this disclosure, we succeeded in improving the lithium ion transport fraction by surface-modifying the inorganic filler with fluorinated alkyl. This is thought to be because surface modification with fluorinated alkyl induces FF interactions between the inorganic filler and the F-containing anion, resulting in a decrease in the relative mobility of the F-containing anion with respect to lithium ions. Furthermore, since fluorinated alkyl is introduced to the inorganic filler surface in advance through surface modification, it is thought that the dispersibility of the inorganic filler and fluorinated alkyl in the solid electrolyte material was improved.

[0016] The Li salt having an F-containing anion is not particularly limited, but may include, for example, at least one selected from the group consisting of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium fluorosulfonyl(trifluoromethanesulfonyl)imide (LiFTFSI), LiPF6, LiBF4, and LiCF3SO3 (LiTfO). In the solid electrolyte material, the content of the Li salt having an F-containing anion is not particularly limited. For example, it may be 40% by mass or more, 60% by mass or more, 96% by mass or less, or 85% by mass or less, relative to the total amount of the solid electrolyte material.

[0017] Examples of inorganic fillers include SiO2, Al2O3, TiO2, ZrO2, and MgO, and may contain at least one selected from the group consisting of SiO2, TiO2, ZrO2, and MgO. The average particle size of the inorganic filler is not particularly limited, but may be, for example, 0.1 μm to 0.2 μm.

[0018] The inorganic filler is surface-modified with fluorinated alkyl. By introducing fluorinated alkyl to the surface of the inorganic filler, FF interactions are introduced between the inorganic filler and the F-containing anion, and the dispersion state of the inorganic filler and fluorinated alkyl in the solid electrolyte material can be improved. In this disclosure, a fluorinated alkyl group may have a structure in which some or all of the hydrogen atoms in the alkyl carbon chain are substituted with fluorine atoms, and may also have a structure that includes groups or elements other than the fluorinated alkyl group. In a fluorinated alkyl group, the number of carbon atoms in the alkyl carbon chain is not particularly limited, and may be, for example, 1 to 12 or 3 to 10. Furthermore, the fluorinated alkyl group may have a branched structure. Specific examples of fluorinated alkyl groups include structures containing at least one of the following: a 1H,1H,2H,2H-tridecafluoro-n-octyl group and a 1H,1H,2H,2H-heptadecafluorodecyl group.

[0019] The method for surface-modifying inorganic fillers with fluorinated alkyl groups is not particularly limited, and examples include surface treatment of inorganic fillers with silane coupling agents. Known methods can be used for surface treatment with silane coupling agents. The trimethoxy(1H,1H,2H,2H-tridecafluoro-n-octyl)silane, represented by the following structural formula (1), can be used as a silane coupling agent, and can introduce a modifying group containing a 1H,1H,2H,2H-tridecafluoro-n-octyl group to the inorganic filler surface. Similarly, the trimethoxy(1H,1H,2H,2H-heptadecafluorodecyl)silane, represented by the following structural formula (2), can introduce a modifying group containing a 1H,1H,2H,2H-heptadecafluorodecyl group to the inorganic filler surface.

[0020] [ka]

[0021] In the solid electrolyte material, the content of the inorganic filler surface-modified with fluorinated alkyl may be, for example, 1% by mass or more and 10% by mass or less, relative to the total amount of the solid electrolyte material.

[0022] Examples of polymers include polyvinylidene fluoride, polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethacrylonitrile, polyvinyl butyral, polyvinyl formal, polyvinylpyrrolidone, styrene butadiene rubber, nitrile butadiene rubber, and combinations thereof. The number-average molecular weight Mn of the polymer is not particularly limited, but may be between 3,000 and 200,000, or between 5,000 and 100,000. The polymer content in the solid electrolyte material may be 3% by mass or more, 30% by mass or less, or 10% by mass or less, relative to the total amount of the solid electrolyte material. Below 3% by mass, the required strength of the solid electrolyte material may not be obtained. Furthermore, exceeding 30% by mass may reduce the ion transport fraction. By applying polymers to solid electrolyte materials, the lithium transport rate can be improved, and the solid electrolyte material can be given the function of a separator.

[0023] The solid electrolyte material of this disclosure may contain components other than those described above. Other components include, for example, succinonitrile (hereinafter sometimes referred to as SN). Sucinonitrile is a flexible crystal existing as NCCH2CH2CN and can increase the ionic conductivity of the solid electrolyte material as a solid solvent. The succinonitrile content in the solid electrolyte material may be 1 to 10 moles, or 2 to 4 moles, per mole of Li salt containing a F-containing anion, from the viewpoint of increasing the ionic conductivity of the solid electrolyte material.

[0024] B.Battery The battery in this disclosure comprises a positive electrode layer, a negative electrode layer, and an electrolyte layer, and typically includes a positive electrode containing a positive electrode layer and a negative electrode containing a negative electrode layer. Figure 1 is a schematic cross-sectional view illustrating a battery in this disclosure. The battery 10 shown in Figure 1 includes a positive electrode layer 1, a negative electrode layer 2, an electrolyte layer 3 disposed between the positive electrode layer 1 and the negative electrode layer 2, a positive electrode current collector 4 for collecting current from the positive electrode layer 1, and a negative electrode current collector 5 for collecting current from the negative electrode layer 2. In this disclosure, the electrolyte layer 3 includes the solid electrolyte material described in "A. Solid Electrolyte Material" above. By using the solid electrolyte material of this disclosure, a battery with excellent lithium-ion conductivity can be obtained.

[0025] The battery in this disclosure may be a solid-state battery in which the electrolyte layer contains a solid electrolyte. The solid-state battery may be a semi-solid-state battery or a fully solid-state battery. In this disclosure, a semi-solid-state battery is a battery in which the electrolyte layer contains a solid electrolyte and a liquid component (e.g., a solvent and an electrolyte solution). In this disclosure, a fully solid-state battery is a battery in which the electrolyte layer has only a solid electrolyte as the electrolyte.

[0026] [Positive electrode] The positive electrode has a positive electrode layer and, if necessary, further has a positive electrode current collector. The positive electrode layer is a layer containing at least a positive electrode active material. The positive electrode layer may also optionally contain at least one of a solid electrolyte, a conductive material, and a binder.

[0027] Examples of positive electrode active materials include oxide active materials. Examples of oxide active materials include LiCoO2, LiMnO2, LiNiO2, LiVO2, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 Rock salt layered active materials such as O2, LiMn2O4, Li4Ti5O 12 , and Li(Ni 0.5 Mn 1.5 Examples include spinel-type active materials such as O4, and olivine-type active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4. A coating layer containing a Li-ion conductive compound may be formed on the surface of the positive electrode active material. This is because it can suppress the reaction between the positive electrode active material and the solid electrolyte (especially sulfide solid electrolytes). Examples of Li-ion conductive compounds include B2O3, Li2B4O7, LiBPO4, Li3PO4, LiPO3, and LiNbO3. The thickness of the coating layer is, for example, 1 nm to 30 nm. The coverage rate of the Li-ion conductive compound coating the positive electrode active material is, for example, 70% or more, may be 90% or more, or may be 100%. The method of coating with the Li-ion conductive compound is not particularly limited, and conventionally known methods can be used as appropriate.

[0028] The positive electrode active material is usually particulate. The positive electrode active material may be primary particles or secondary particles formed by aggregation of primary particles. The average particle size (D50) of the positive electrode active material is not particularly limited, but for example, it may be 0.01 μm or more and 50 μm or less, or 0.5 μm or more and 30 μm or less.

[0029] The proportion of positive electrode active material in the positive electrode layer is, for example, 20% by mass or more, may be 30% by mass or more, or 40% by mass or more. If the proportion of positive electrode active material is too low, a sufficient energy density may not be obtained. On the other hand, the proportion of positive electrode active material in the positive electrode layer is, for example, 80% by mass or less, may be 70% by mass or less, or 60% by mass or less. If the proportion of positive electrode active material is too high, the ionic conductivity and electronic conductivity in the positive electrode layer may relatively decrease.

[0030] The positive electrode layer may contain a solid electrolyte. Adding a solid electrolyte improves the ionic conductivity of the positive electrode layer. The solid electrolyte may be an inorganic solid electrolyte such as a sulfide solid electrolyte, halide solid electrolyte, oxide solid electrolyte, or complex hydride solid electrolyte, or an organic solid electrolyte such as a gel electrolyte. The solid electrolyte may be one of the solid electrolyte materials described in "A. Solid Electrolyte Materials" above.

[0031] A sulfide solid electrolyte is an electrolyte containing S element. A sulfide solid electrolyte usually contains at least Li element and S element. The sulfide solid electrolyte may further contain Me element (Me is at least one of P, As, Sb, Si, Ge, Sn, Bi, Al, Zn, Ga, and In). Also, the sulfide solid electrolyte may contain halogen elements such as F, Cl, Br, and I.

[0032] The sulfide solid electrolyte may be a glassy (amorphous) sulfide solid electrolyte, a glass-ceramic sulfide solid electrolyte, or a crystalline sulfide solid electrolyte. The sulfide solid electrolyte may have a crystalline phase. Examples of the above crystalline phase include Thio-LISICON type crystalline phase, argyrodite type crystalline phase, and LGPS type crystalline phase, etc.

[0033] The composition of the sulfide solid electrolyte is not particularly limited. For example, xLi2S·(1 - x)P2S5 (0.5 ≦ x < 1), and yLiI·zLiBr·(100 - y - z)(xLi2S·(1 - x)P2S5) (0.5 ≦ x < 1, 0 ≦ y ≦ 30, 0 ≦ z ≦ 30), etc. can be mentioned. In these compositions, x may satisfy 0.7 ≦ x ≦ 0.8. Also, as other examples of the composition of the sulfide solid electrolyte, Li 7-x PS 6-x X x can be mentioned. X is at least one of F, Cl, Br, I, and x satisfies 0 ≦ x < 2. Also, as other examples of the composition of the sulfide solid electrolyte, Li 4-x Me 1-x P x S4 (0 < x < 1) can be mentioned. Me is the same as the above definition. Examples of the sulfide solid electrolyte include LiI - LiBr - Li2S - P2S5, LiI - Li2S - P2S5, LiI - Li2S - P2O5, and LiI - Li3PO4 - P2S5, etc.

[0034] Examples of oxide solid electrolytes include materials having a garnet-type crystal structure containing elements Li, La, A (where A is at least one of Zr, Nb, Ta, and Al), and O. Examples of oxide solid electrolytes include Li2O-B2O3-P2O5, Li2O-SiO2, Li2O-B2O3, Li 1.3 Al 0.3 Ti 0.7 (PO4)3, Li5La3Ta2O 12 Li7La3Zr2O 12 Li6BaLa2Ta2O 12 Li 3.6 Si 0.6 P 0.4 O4, Li4SiO4, Li3PO4, and Li 3+x PO 4-x N x (1 ≤ x ≤ 3) or similar conditions may also be acceptable.

[0035] The halide solid electrolyte may be, for example, a solid electrolyte containing Li, M, and X (where M represents at least one of Ti, Al, and Y, and X represents F, Cl, or Br).

[0036] The solid electrolyte may be in particulate form from the standpoint of ease of handling. Furthermore, the average particle size (D50) of the solid electrolyte particles is not particularly limited and may range from 1 nm to 100 μm.

[0037] The proportion of solid electrolyte in the positive electrode layer is, for example, 10% by mass or more, may be 20% by mass or more, or 30% by mass or more. If the proportion of solid electrolyte is too low, there may be insufficient ion conduction paths in the positive electrode layer. On the other hand, the proportion of solid electrolyte in the positive electrode layer is, for example, 60% by mass or less, may be 50% by mass or less. If the proportion of solid electrolyte is too high, the proportion of positive electrode active material will be relatively low, which may result in a lower energy density.

[0038] The positive electrode layer may contain a conductive material. Adding a conductive material improves the electronic conductivity of the positive electrode layer. Examples of conductive materials include carbon materials, metal particles, and conductive polymers. Examples of carbon materials include particulate carbon materials such as acetylene black (AB) and Ketjenblack (KB), and fibrous carbon materials such as vapor-processed carbon fiber (VGCF), carbon nanotubes (CNT), and carbon nanofibers (CNF).

[0039] The proportion of conductive material in the positive electrode layer is, for example, 0.1% by mass or more, may be 0.5% by mass or more, or 1.0% by mass or more. If the proportion of conductive material is too low, there may be insufficient electron conduction paths in the positive electrode layer. On the other hand, the proportion of conductive material in the positive electrode layer is, for example, 5% by mass or less, may be 3% by mass or less. If the proportion of conductive material is too high, the proportion of positive electrode active material will be relatively low, which may result in a lower energy density.

[0040] The positive electrode layer may contain a binder. Examples of binders include styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), butadiene rubber (BR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-isoprene-styrene block copolymer (SIS), and ethylene-propylene-diene copolymer (EPDM).

[0041] The proportion of binder in the positive electrode layer may be, for example, 0.5% by mass or more, 1.0% by mass or more, or 1.5% by mass or more. If the proportion of binder is too low, the increase in resistance due to charging and discharging may not be sufficiently reduced. On the other hand, the proportion of binder in the positive electrode layer may be, for example, 5% by mass or less, or 3% by mass or less. If the proportion of binder is too high, the proportion of positive electrode active material will be relatively low, which may result in a lower energy density.

[0042] The thickness of the positive electrode layer may be, for example, 0.1 μm or more and 1000 μm or less, 1 μm or more and 500 μm or less, or 30 μm or more and 100 μm or less.

[0043] The method for manufacturing the positive electrode layer is not particularly limited, but for example, it may involve mixing the positive electrode active material, the solid electrolyte, and a solvent to obtain a positive electrode slurry, coating the positive electrode slurry onto a positive electrode current collector, drying it, and forming a positive electrode layer. When forming the positive electrode layer, a pressing process may be performed to press the positive electrode layer in the thickness direction. Examples of pressing processes include roller pressing and flat plate pressing. Examples of solvents include tetralin, diisobutyl ketone, butyl butyrate, mesitylene, heptane, dibutyl ether, decane, dodecane, isodecane, and toluene, and may contain two or more of these components.

[0044] Examples of materials for the positive electrode current collector include SUS, Cr, Au, Pt, Zn, aluminum, copper, nickel, iron, titanium, and carbon. The thickness of the positive electrode current collector is, for example, 0.1 μm or more and 100 μm or less. The shape of the positive electrode current collector may be foil-like or plate-like. The planar shape of the positive electrode current collector is not particularly limited, but examples include circular, elliptical, rectangular, and any polygonal shape. The positive electrode current collector may have a buffer layer, an elastic layer, or a PTC (Positive Temperature Coefficient) thermistor layer on its surface.

[0045] [Negative electrode] The negative electrode has a negative electrode layer and, if necessary, further has a negative electrode current collector. The negative electrode layer is a layer containing at least a negative electrode active material. The negative electrode layer may also optionally contain at least one of a solid electrolyte, a conductive material, and a binder. The negative electrode layer contains at least one of either elemental Li or a Li alloy as the negative electrode active material. Examples of metallic elements other than lithium included in the Li alloy include Mg, Ag, In, Sn, Si, Ga, Au, and Pt. The solid electrolyte, conductive material, and binder used in the negative electrode layer are the same as those described above for the positive electrode layer.

[0046] Examples of materials for the negative electrode current collector include SUS, aluminum, copper, nickel, iron, titanium, and carbon. The thickness of the negative electrode current collector varies depending on its shape, but may be in the range of, for example, 1 μm to 50 μm. The shape of the negative electrode current collector may be foil-like or plate-like. The planar shape of the negative electrode current collector is not particularly limited, but examples include circular, elliptical, rectangular, and any polygonal shape. The negative electrode current collector may have a buffer layer, an elastic layer, or a PTC thermistor layer on its surface.

[0047] [Electrolyte layer] The electrolyte layer is a layer formed between the positive electrode layer and the negative electrode layer, and contains at least a solid electrolyte. The solid electrolyte is the solid electrolyte material described in "A. Solid Electrolyte Material" above. The proportion of solid electrolyte in the electrolyte layer is not particularly limited, but may be, for example, 50% by mass or more, and may be in the range of 60% by mass or more and 100% by mass or less, or in the range of 70% by mass or more and 100% by mass or less, or 100% by mass.

[0048] Solid electrolytes can be used individually or in combination of two or more types. When using two or more types of solid electrolytes, they may be mixed together, or two or more layers of solid electrolytes may be formed to create a multilayer structure. The electrolyte layer may further contain a solid electrolyte other than the "A. Solid Electrolyte Material" described above. Examples of solid electrolytes other than the "A. Solid Electrolyte Material" include solid electrolytes that can be incorporated into the positive electrode layer as described above.

[0049] The electrolyte layer may contain an electrolyte solution. Including an electrolyte solution can improve ionic conductivity. To avoid a decrease in mechanical strength at high temperatures, the amount of electrolyte solution may be, for example, less than 10% by mass, 5% by mass or less, 1% by mass or less, or 0.5% by mass or less, relative to the total volume of the electrolyte layer. Aqueous electrolytes and non-aqueous electrolytes can be used as the electrolyte. These may be used individually or in combination of two or more types. Conventional and known aqueous and non-aqueous electrolytes can be used.

[0050] The electrolyte layer may be impregnated with the electrolyte and may also use a separator that prevents contact between the positive electrode layer and the negative electrode layer. The material for the separator is not particularly limited as long as it is a porous membrane. Examples include polyethylene (PE), polypropylene (PP), polyester, polyvinyl alcohol, cellulose, and polyamide resins, with polyethylene and polypropylene being particularly preferred. The separator may have a single-layer structure or a multi-layer structure. Examples of multi-layer separators include a PE / PP two-layer separator, or a PP / PE / PP or PE / PP / PE three-layer separator. The separator may be made of nonwoven fabrics such as resin nonwoven fabric and glass fiber nonwoven fabric.

[0051] The thickness of the electrolyte layer is, for example, 0.1 μm or more and 1000 μm or less, and may be 0.1 μm or more and 500 μm or less, or 0.1 μm or more and 100 μm or less.

[0052] [others] The battery in this disclosure may further include a restraining jig that applies restraining pressure along the thickness direction to the positive electrode layer, electrolyte layer, and negative electrode layer. When the electrolyte layer is a solid electrolyte layer, good ion conduction paths and electron conduction paths can be formed. The restraining pressure is, for example, 0.1 MPa or more, may be 1 MPa or more, or 5 MPa or more. On the other hand, the restraining pressure is, for example, 100 MPa or less, may be 50 MPa or less, or 20 MPa or less.

[0053] The type of battery described herein is not particularly limited, but is typically a lithium-ion battery. Furthermore, the battery described herein may be a primary battery or a secondary battery, and is particularly favored as a secondary battery because it can be repeatedly charged and discharged, making it useful, for example, as an in-vehicle battery. The shape of the battery is not particularly limited and may be, for example, coin-type, cylindrical, prismatic, sheet-type, button-type, flat-type, or stacked-type.

[0054] Applications of batteries include, for example, powering vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), gasoline cars, and diesel cars. In particular, they may be used as power sources for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or battery electric vehicles (BEVs). Batteries may also be used as power sources for mobile devices other than vehicles (e.g., trains, ships, aircraft), and as power sources for electrical products such as information processing devices. [Examples]

[0055] [Example 1] <Preparation of surface-modified SiO2(1)> In an Ar glove box, 2 g of SiO2 (Sigma-Aldrich, average particle size 0.1 μm to 0.2 μm), 20 g of super-dehydrated ethanol (Fujifilm Wako Pure Chemical Industries), and 0.15 g of trimethoxy(1H,1H,2H,2H-tridecafluoro-n-octyl)silane (structural formula (1) above, Tokyo Chemical Industries) were weighed and stirred in a sealed reaction vessel at 50°C for 16 hours to carry out the silane coupling reaction. The solution after the stirring reaction was filtered by suction, and the washing and filtering with 30 mL of ethanol was repeated 5 times. The obtained solid was vacuum-dried at 100°C for 12 hours. In this way, surface-modified SiO2(1) was obtained by substituting the SiO2 surface with modifying groups containing fluorinated alkyl groups.

[0056] <Preparation of solid electrolyte materials> In an Ar-atmosphere glove box, succinonitrile (Sigma-Aldrich) and LITFSI (Sigma-Aldrich) were weighed in a molar ratio of SN:LITFSI = 4:1 and stirred at 70°C for 24 hours. To the resulting solution, polyethylene oxide (Sigma-Aldrich, number average molecular weight Mn = 6000) was added at a concentration of 10% by mass relative to the total amount of solid electrolyte material, and surface-modified SiO2(1) was added at a concentration of 5% by mass relative to the total amount of solid electrolyte material. The mixture was then stirred at 70°C for another 24 hours to obtain the solid electrolyte material.

[0057] [Example 2] <Preparation of surface-modified SiO2(2)> In Example 1, surface-modified SiO2(2) was obtained by substituting the SiO2 surface with a modifying group containing a fluorinated alkyl group, except that 0.18 g of trimethoxy(1H,1H,2H,2H-heptadecafluorodecyl)silane (structural formula (2) above, manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 0.15 g of trimethoxy(1H,1H,2H,2H-tridecafluoro-n-octyl)silane.

[0058] <Preparation of solid electrolyte materials> A solid electrolyte material was obtained in the same manner as in Example 1, except that surface-modified SiO2(2) was used instead of surface-modified SiO2(1).

[0059] [Comparative Example 1] <Preparation of solid electrolyte materials> A solid electrolyte material was obtained in the same manner as in Example 1, except that surface-modified SiO2(1) was not used.

[0060] [Comparative Example 2] <Preparation of solid electrolyte materials> A solid electrolyte material was obtained in the same manner as in Example 1, except that unmodified SiO2 (manufactured by Sigma-Aldrich, average particle size 0.1 μm to 0.2 μm) was used instead of surface-modified SiO2(1).

[0061] [Comparative Example 3] <Preparation of surface-modified SiO2(3)> In Example 1, surface-modified SiO2 (3) was obtained by substituting the SiO2 surface with a modifying group containing a non-fluorinated alkyl group, except that 0.06 g of hexyltrimethoxysilane (structural formula (3) below, manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 0.15 g of trimethoxy(1H,1H,2H,2H-tridecafluoro-n-octyl)silane.

[0062] [ka]

[0063] <Preparation of solid electrolyte materials> A solid electrolyte material was obtained in the same manner as in Example 1, except that surface-modified SiO2(3) was used instead of surface-modified SiO2(1).

[0064] [Measurement of lithium ion transport fraction] The lithium ion transport fraction of the solid electrolyte materials obtained in Examples 1-2 and Comparative Examples 1-3 described above was measured as follows. First, the solid electrolyte material was heated to 60°C and impregnated into a polypropylene separator. Next, coin cells were fabricated using this impregnated separator with a configuration of Li metal / impregnated separator / Li metal. The fabricated coin cells were left to stand in a 50°C constant temperature bath for 12 hours. After standing, AC impedance measurements were performed at 50°C in the frequency range of 1Hz-1MHz using a potentiostat / galvanostat (VMP3, Biologic). The measured resistance was defined as the pre-polarization impedance R0 (Ω). Next, a DC polarization measurement was performed at 10mV for 3600 seconds. The initial current value at this time is the pre-polarization current value I0(A), and the current value in the steady state (after 3600 seconds) is the post-polarization current value I S (A) was chosen. Furthermore, AC impedance measurements were performed in the frequency range of 1 Hz to 1 MHz. At this time, the measured resistance was divided into polarization impedance R. S (Ω) Using the obtained values, the lithium ion transport fraction t is calculated using the following formula. Li+ The following equation was obtained. In the equation below, V is the applied voltage (V). The results are shown in Table 1.

[0065]

number

[0066] [Table 1]

[0067] As shown in Table 1, the solid electrolyte materials of Examples 1 and 2, which used inorganic fillers (SiO2) surface-modified with fluorinated alkyl, showed a higher lithium ion transport fraction compared to Comparative Example 1, which did not use inorganic fillers (SiO2), Comparative Example 2, which used inorganic fillers (SiO2) without surface modification, and Comparative Example 3, which used inorganic fillers (SiO2) surface-modified with unfluorinated alkyl groups. [Explanation of symbols]

[0068] 1 … Positive electrode layer 2 …negative electrode layer 3 …electrolyte layer 4 …Positive current collector 5 … Negative current collector 10 … batteries

Claims

1. A solid electrolyte material, The solid electrolyte material comprises a Li salt having a fluorine-containing anion, an inorganic filler, and a polymer. The inorganic filler is a solid electrolyte material whose surface is modified with a fluorinated alkyl group.

2. The solid electrolyte material according to claim 1, further comprising succinonitrile.

3. The inorganic filler is SiO ２ , TiO ２ , ZrO ２ , and at least one selected from the group consisting of MgO, The solid electrolyte material according to claim 1, wherein the fluorinated alkyl group comprises at least one of a 1H,1H,2H,2H-tridecafluoro-n-octyl group and a 1H,1H,2H,2H-heptadecafluorodecyl group.

4. The Li salts mentioned above include lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium fluorosulfonyl(trifluoromethanesulfonyl)imide (LiFTFSI), and LiPF ６ LiBF ４ , and LiCF ３ SO ３ The solid electrolyte material according to claim 1, comprising at least one selected from the group consisting of (LiTfO).

5. A battery having a positive electrode layer, a negative electrode layer, and an electrolyte layer, The electrolyte layer includes a solid electrolyte, A battery in which the solid electrolyte is the solid electrolyte material according to any one of claims 1 to 4.

Images