JP6891804B2 - Solid state battery - Google Patents

Description

The present disclosure relates to solid state batteries.

The solid-state battery is a battery having a solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer, and the safety device can be simplified as compared with a liquid-based battery having an electrolytic solution containing a flammable organic solvent. It has the advantage of being easy.

Much research has been done on the solid electrolyte layer. For example, Patent Document 1 discloses a solid electrolyte sheet containing a glass solid electrolyte containing at least a lithium element (Li) and a sulfur element (S) and a support made of an electron-insulating inorganic fiber. The object of this technique is to provide a self-supporting solid electrolyte sheet having a large area.

Further, Patent Document 2 includes a solid electrolyte and a support having a plurality of openings, the solid electrolyte has a continuous penetration structure in the thickness direction at the openings of the support, and the support is made of glass to support the support. A solid electrolyte sheet having an aperture ratio of 40 to 90% of the body is disclosed. An object of this technique is to provide a solid electrolyte sheet having a large area, in which the ionic conductivity is hardly lowered even if a support is introduced for the sheet independence.

On the other hand, Patent Document 3 includes an intervening layer made of a lithium salt-containing polymer or an ionic liquid and interposed between a positive electrode member and a negative electrode member, and the negative electrode active material contains a specific negative electrode active material. Non-aqueous electrolyte batteries are disclosed. This technology has an object of improving charge / discharge cycle characteristics. Further, although the battery does not use an inorganic solid electrolyte such as a sulfide solid electrolyte, Patent Document 4 discloses a lithium storage battery in which a separator is impregnated with a specific ionic liquid electrolyte.

Japanese Unexamined Patent Publication No. 2014-096311 Japanese Unexamined Patent Publication No. 2008-103258 Japanese Unexamined Patent Publication No. 2012-014892 Special Table 2013-541820

For example, as described in Patent Document 1, the solid electrolyte layer (solid electrolyte sheet) can be made self-supporting by using the support, and the solid electrolyte layer can be treated as a single membrane. Further, in Patent Document 1, a sulfide solid electrolyte is arranged on both sides of the support and pressed to form a solid electrolyte layer (solid electrolyte sheet). On the other hand, since the sulfide solid electrolyte is a solid, it is difficult to fill the inside of the support with the sulfide solid electrolyte. As a result, the ionic conductivity of the solid electrolyte layer decreases.

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a solid-state battery having a support and a solid electrolyte layer in which a decrease in ionic conductivity is suppressed.

In order to solve the above problems, in the present disclosure, a solid battery having a positive electrode active material layer, a negative negative active material layer, and a solid electrolyte layer arranged between the positive positive active material layer and the negative negative active material layer. The solid electrolyte layer has a first solid electrolyte part, a support having pores, and a second solid electrolyte part in this order, and the first solid electrolyte part has a Li element and a P element. And the first sulfide solid electrolyte containing the S element, the second solid electrolyte part contains the second sulfide solid electrolyte containing the Li element, the P element and the S element, and the above-mentioned support. Provided is a solid-state battery in which the pores are filled with a solvated ion liquid containing a Li salt and a Lewis base.

According to the present disclosure, since the pores of the support are filled with the solvated ionic liquid, it is possible to obtain a solid-state battery having a support and a solid electrolyte layer in which a decrease in ionic conductivity is suppressed. it can.

The present disclosure has an effect that it is possible to provide a solid-state battery having a support and a solid electrolyte layer in which a decrease in ionic conductivity is suppressed.

It is the schematic cross-sectional view which illustrates the solid-state battery of this disclosure. It is a schematic cross-sectional view which illustrates the solid electrolyte layer in this disclosure. It is the result of the ionic conductivity measurement with respect to the solid electrolyte layer obtained in Example 3, Comparative Example 1 and Reference Example 1.

Hereinafter, the solid-state battery of the present disclosure will be described in detail.

FIG. 1 is a schematic cross-sectional view showing an example of the solid-state battery of the present disclosure. The solid battery 10 shown in FIG. 1 has a positive electrode active material layer 1, a negative electrode active material layer 2, a solid electrolyte layer 3 arranged between the positive electrode active material layer 1 and the negative electrode active material layer 2, and a positive electrode active material layer. It has a positive electrode current collector 4 that collects electricity from 1 and a negative electrode current collector 5 that collects electricity from the negative electrode active material layer 2.

Further, as shown in FIG. 2, the solid electrolyte layer 3 has a first solid electrolyte portion 31, a support 33 having pores, and a second solid electrolyte portion 32 in this order. The first solid electrolyte part 31 contains a first sulfide solid electrolyte containing Li element, P element and S element, and the second solid electrolyte part 32 contains a second element containing Li element, P element and S element. Contains a sulfide solid electrolyte. The pores of the support 33 are filled with a solvated ionic liquid containing a Li salt and a Lewis base.

According to the present disclosure, since the pores of the support are filled with the solvated ionic liquid, it is possible to obtain a solid-state battery having a support and a solid electrolyte layer in which a decrease in ionic conductivity is suppressed. it can.

As described above, the solid electrolyte layer can be made independent by using the support, and the solid electrolyte layer can be treated as a single membrane. Therefore, there is an advantage that the battery manufacturing process can be simplified. Further, when the solid electrolyte layer does not have a support, a short circuit is likely to occur when cracks occur due to local stress associated with charging / discharging. On the other hand, when the solid electrolyte layer has a support, it is possible to prevent cracks from occurring in the entire solid electrolyte layer even when local stress due to charging / discharging is applied, and short circuits are less likely to occur. There is an advantage.

On the other hand, as described above, it is known that a solid electrolyte layer (solid electrolyte sheet) is formed by arranging sulfide solid electrolytes on both sides of the support and pressing them. However, since the sulfide solid electrolyte is a solid, it is difficult to fill the sulfide solid electrolyte into the inside of the support. As a result, the number of ionic conduction paths inside the support is reduced, and the ionic conductivity of the solid electrolyte layer is reduced. In particular, when the pores of the support are small or when the support has a complicated structure such as a porous structure, the ionic conductivity of the solid electrolyte layer is remarkably lowered.

On the other hand, in the present disclosure, the pores of the support are filled with a solvated ionic liquid. Since the solvated ionic liquid easily penetrates into the pores, it is easy to secure an ionic conduction path inside the support. Therefore, it is possible to obtain a solid electrolyte layer that has a support and suppresses a decrease in ionic conductivity. Further, since a general ionic liquid easily reacts with a sulfide solid electrolyte, ionic conduction in the solid electrolyte layer may be hindered. On the other hand, the solvated ionic liquid has an advantage that it does not react with the sulfide solid electrolyte and the ionic conduction in the solid electrolyte layer is not easily inhibited because the solvated ionic liquid has very high chemical stability. Further, in the present disclosure, since the first solid electrolyte portion and the second solid electrolyte portion are arranged so as to sandwich the support, it is possible to suppress the reaction of the solvated ionic liquid with the positive electrode active material and the negative electrode active material. There are advantages.
Hereinafter, the solid-state battery of the present disclosure will be described for each configuration.

1. 1. Solid electrolyte layer The solid electrolyte layer is a layer arranged between the positive electrode active material layer and the negative electrode active material layer. The solid electrolyte layer has a first solid electrolyte portion, a support having pores, and a second solid electrolyte portion in this order. The thickness of the solid electrolyte layer is, for example, 5 μm or more and 1000 μm or less.

(1) Support The support has pores and is usually electronically insulating. Examples of the material of the support include an organic material such as resin and an inorganic material such as ceramics and glass. Examples of the resin include polyimide and polyolefin.

The average pore diameter of the pores is not particularly limited, but may be, for example, 50 μm or less, 30 μm or less, or 10 μm or less. On the other hand, the average pore diameter of the pores is, for example, 0.1 μm or more. The average pore diameter of the pores can be determined by observing a cross-sectional image of the support. In one hole, the maximum length in the cross-sectional image is L1, and the maximum length of the hole orthogonal to the maximum length is L2. The average of L1 and L2 is taken as the diameter of the hole. This measurement can be performed on, for example, 100 or more pores, and the average of them can be taken as the average pore diameter of the pores.

The opening ratio of the support is not particularly limited, but may be, for example, 20% or more, 40% or more, or 50% or more. On the other hand, the opening ratio of the support is, for example, 90% or less. The aperture ratio of the support can be calculated from the density and true density of the support. The true density can be determined, for example, by dry density measurement by a constant volume expansion method.

The support may have a porous structure. Specific examples include a resin film having a porous structure. Further, the support may have a woven fabric structure or a non-woven fabric structure. The woven fabric structure refers to a structure in which fibers (for example, resin fibers and glass fibers) are regularly arranged, and the non-woven fabric structure refers to a structure in which fibers (for example, resin fibers and glass fibers) are randomly arranged. The thickness of the support is, for example, 5 μm or more, and may be 10 μm or more. On the other hand, the thickness of the support is, for example, 50 μm or less.

Further, the pores of the support are filled with a solvated ionic liquid containing a Li salt and a Lewis base. In a solvated ionic liquid containing a Li salt and a Lewis base, a Lewis base is coordinated (solvated) with the Li ion of the Li salt to form a complex cation, and the anion of the Li salt becomes an anion of the solvated ionic liquid. The melting point of the solvated ionic liquid may be 80 ° C. or lower, or 60 ° C. or lower. On the other hand, the melting point of the solvated ionic liquid is, for example, 0 ° C. or higher. In particular, the solvated ionic liquid is preferably a liquid at 25 ° C. Further, the complex cation preferably has a Li ion and a Lewis base in a molar ratio of, for example, Li ion: Lewis base = 1: 1.

The Li salt preferably contains one Li ion in one molecule. Examples of the Li salt anion include an imide anion represented by a bis (fluoromethanesulfonyl) imide (FSI) anion, a bis (trifluoromethanesulfonyl) imide (TFSI) anion, a hexafluorophosphate anion, and a tris (penta). Examples thereof include a phosphate anion represented by a fluoroethyl) trifluorophosphate anion, a tetrafluoroborate (TFB) anion, and a triflate anion.

Examples of Lewis bases include grime. Examples of the glyme include diethylene glycol diethyl ether (G2, diglyme), triethylene glycol dimethyl ether (G3, triglime), tetraethylene glycol dimethyl ether (G4, tetraglyme), diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, and triethylene glycol methyl ethyl. Examples thereof include ether and triethylene glycol butyl methyl ether.

The molar ratio of the Li salt to the Lewis base is, for example, 0.1 or more, 0.5 or more, 0.8 or more, or 1.0 or more. On the other hand, the molar ratio of the Li salt to the Lewis base is, for example, 3.0 or less, may be 2.5 or less, or may be 2.0 or less.

Further, in the support filled with the solvated ionic liquid, the ratio of the volume occupied by the solvated ionic liquid to the total pore volume of the support is, for example, 50% or more, and may be 90% or more. It may be 95% or more.

(2) First solid electrolyte part The first solid electrolyte part contains a first sulfide solid electrolyte containing Li element, P element and S element. Moreover, the first solid electrolyte part may contain a binder if necessary.

The primary sulfide solid electrolyte usually contains a Li element, a P element, and an S element. Further, the first sulfide solid electrolyte may further contain at least one of Cl element, Br element and I element. Further, the first sulfide solid electrolyte may further contain at least one of Ge element, Si element and Sn element. Further, the first sulfide solid electrolyte may further contain an O element.

The first sulfide solid electrolyte may contain an ionic conductor containing an element Li, an element P and an element S. Ion conductor preferably contains PS ₄ ^3- as principal anionic structures. The "PS ₄ ^3- and mainly anionic structure", the percentage of PS ₄ ^3- is, refers to the most common among all anion structures in the ionic conductor. _PS ^{4 3-} percentage of the total anionic structures are, for example not less than 60 mol%, may be more than 70 mol%, may be more than 80 mol%, may be more than 90 mol%. PS ₄ ^3- proportion of, for example, can be determined Raman spectroscopy, NMR, by XPS. Further, a part of the S element of the ionic conductor may be replaced with the O element.

When the first sulfide solid electrolyte contains the above-mentioned ionic conductor, it may further contain LiX. Examples of LiX include LiCl, LiBr and LiI. Further, it is preferable that at least a part of LiX exists as a LiX component in a state of being incorporated into the structure of the ionic conductor. The ratio of LiX in the first sulfide solid electrolyte is, for example, 1 mol% or more, and may be 10 mol% or more. On the other hand, the ratio of LiX is, for example, 50 mol% or less, and may be 35 mol% or less. The first sulfide solid electrolyte has a composition represented by xLiX · (100−x) (0.75Li ₂ S · 0.25P ₂ S ₅ ) (x satisfies 0 ≦ x ≦ 50). You may.

The first sulfide solid electrolyte as an anion structure, and _{^{PS 4 3-, GeS 4 4-,}} SiS 4 4-, may have at least one _SnS ^{4 4-.}

The first sulfide solid electrolyte may be amorphous or crystalline. An example of the former is sulfide glass, and an example of the latter is crystallized sulfide glass (glass ceramics). Further, the first sulfide solid electrolyte may have a so-called LGPS type crystal phase.

Examples of the shape of the first sulfide solid electrolyte include particulate matter. The average particle size (D ₅₀ ) of the first sulfide solid electrolyte is, for example, 5 μm or more, and may be 10 μm or more. On the other hand, the average particle size (D ₅₀ ) of the first sulfide solid electrolyte is, for example, 200 μm or less, and may be 100 μm or less. The average particle size can be calculated from, for example, measurement by a laser diffraction type particle size distribution meter. The first sulfide solid electrolyte preferably has high ionic conductivity, and the ionic conductivity at 25 ° C. is, for example, 1 × 10 ^-4 S / cm or more, and 1 × 10 ^-3 S / cm or more. There may be.

On the other hand, the first solid electrolyte portion may further contain a binder. Examples of the binder include fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), rubber-based binders such as butadiene rubber, and acrylic-based binders.

The thickness of the first solid electrolyte portion is, for example, 1 μm or more and 300 μm or less. Examples of the method for forming the first solid electrolyte portion include a method of applying and pressing a slurry containing the first sulfide solid electrolyte.

(3) Second solid electrolyte section The second solid electrolyte section contains a disulfide solid electrolyte containing Li element, P element and S element. The details of the second sulfide solid electrolyte are the same as those of the first sulfide solid electrolyte described above, and thus the description thereof is omitted here. The first sulfide solid electrolyte and the second sulfide solid electrolyte may be the same material or different materials from each other. Moreover, the second solid electrolyte part may contain a binder. The binder is also as described above. The thickness of the second solid electrolyte portion is, for example, 1 μm or more and 300 μm or less.

2. Positive electrode active material layer The positive electrode active material layer is a layer containing at least a positive electrode active material. The positive electrode active material layer may contain at least one of a solid electrolyte, a conductive material and a binder, if necessary.

The positive electrode active material is not particularly limited, but typically includes an oxide active material. Examples of the oxide active material include rock salt layered active materials _{such as LiCoO 2} , LiMnO ₂ , LiNiO ₂ , LiVO ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O _{2 , LiMn 2} O ₄ , Li ( Examples thereof include spinel-type active materials such as Ni _0.5 Mn _1.5 ) O ₄ and olivine-type active materials such as _{LiFePO 4} , LiMnPO ₄ , LiNiPO ₄ , and LiCuPO _4.

The surface of the positive electrode active material may be coated with a coat layer. The coat layer can suppress the reaction between the positive electrode active material and the solid electrolyte (particularly the sulfide solid electrolyte). Examples of the coat layer include Li-containing oxides such as _{LiNbO 3} , Li ₃ PO _{4, and LiPON.} The average thickness of the coat layer is, for example, 1 nm or more. On the other hand, the average thickness of the coat layer is, for example, 20 nm or less, and may be 10 nm or less.

Examples of the shape of the positive electrode active material include particles. The average particle size (D ₅₀ ) of the positive electrode active material is, for example, 0.1 μm or more and 50 μm or less. The average particle size can be calculated from, for example, measurement by a laser diffraction type particle size distribution meter or a scanning electron microscope (SEM). The ratio of the positive electrode active material contained in the positive electrode active material layer is, for example, 40% by weight or more, 50% by weight or more, or 60% by weight or more. On the other hand, the proportion of the positive electrode active material contained in the positive electrode active material layer is, for example, 95% by weight or less.

The positive electrode active material layer may further contain a solid electrolyte. By adding the solid electrolyte, the ionic conductivity of the positive electrode active material layer can be improved. Examples of the solid electrolyte include a sulfide solid electrolyte and an oxide solid electrolyte. Examples of the sulfide solid electrolyte include the sulfide solid electrolyte described in "1. Solid electrolyte layer" above.

The positive electrode active material layer may further contain a conductive material. By adding the conductive material, the electron conductivity of the positive electrode active material layer can be improved. Examples of the conductive material include acetylene black, ketjen black, and carbon fiber. Further, the positive electrode active material layer may further contain a binder. Examples of the binder include the binder described in "1. Solid electrolyte layer" above.

The thickness of the positive electrode active material layer is, for example, 0.1 μm or more and 1000 μm or less. Examples of the method for forming the positive electrode active material layer include a method in which a slurry containing at least the positive electrode active material and the dispersion medium is applied and dried.

3. 3. Negative electrode active material layer The negative electrode active material layer is a layer containing at least a negative electrode active material. The negative electrode active material layer may contain at least one of a solid electrolyte, a conductive material and a binder, if necessary.

The negative electrode active material is not particularly limited, and examples thereof include a carbon active material, a metal active material, and an oxide active material. Examples of the carbon active material include graphite, hard carbon, and soft carbon. On the other hand, examples of the metal active material include simple substances such as Li, In, Al, Si and Sn, and alloys containing at least one of these elements. Further, examples of the oxide active material include Li ₄ TiO ₅ .

Examples of the shape of the negative electrode active material include a particle shape. The average particle size (D ₅₀ ) of the negative electrode active material is, for example, 0.1 μm or more and 50 μm or less. The average particle size can be calculated from, for example, measurement by a laser diffraction type particle size distribution meter or a scanning electron microscope (SEM). The proportion of the negative electrode active material contained in the negative electrode active material layer is, for example, 40% by weight or more, 50% by weight or more, or 60% by weight or more. On the other hand, the proportion of the negative electrode active material contained in the negative electrode active material layer is, for example, 95% by weight or less.

The solid electrolyte, the conductive material, and the binder used for the negative electrode active material layer are the same as those described in "2. Positive electrode active material layer" above, and thus the description thereof is omitted here. Above all, the negative electrode active material layer preferably contains a sulfide solid electrolyte as a solid electrolyte.

The thickness of the negative electrode active material layer is, for example, 0.1 μm or more and 1000 μm or less. Examples of the method for forming the negative electrode active material layer include a method in which a slurry containing at least the negative electrode active material and the dispersion medium is applied and dried.

4. Other Members The solid-state battery of the present disclosure has at least the above-mentioned positive electrode active material layer, negative electrode active material layer and solid electrolyte layer. Further, usually, it has a positive electrode current collector that collects electricity from the positive electrode active material layer and a negative electrode current collector that collects electricity from the negative electrode active material layer. Examples of the material of the positive electrode current collector include SUS, aluminum, nickel, iron, titanium and carbon. On the other hand, examples of the material of the negative electrode current collector include SUS, copper, nickel and carbon. The thickness and shape of the positive electrode current collector and the negative electrode current collector are preferably selected as appropriate according to the application of the battery. Further, as the battery case used in the present disclosure, a battery case of a general battery can be used, and examples thereof include a battery case made of SUS.

5. Solid-state battery The solid-state battery of the present disclosure is usually a lithium battery. Further, the solid-state battery of the present disclosure may be a primary battery or a secondary battery, and among them, a secondary battery is preferable. This is because it can be charged and discharged repeatedly and is useful as an in-vehicle battery, for example. Further, the solid-state battery of the present disclosure may be a single-layer battery or a laminated battery. The laminated battery may be a monopolar type laminated battery (parallel connection type laminated battery) or a bipolar type laminated battery (series connection type laminated battery). Examples of the shape of the solid-state battery include a coin type, a laminated type, a cylindrical type and a square type.

The present disclosure is not limited to the above embodiment. The above embodiment is an example, and any object having substantially the same structure as the technical idea described in the claims of the present disclosure and exhibiting the same effect and effect is the present invention. Included in the technical scope of the disclosure.

Hereinafter, the present disclosure will be described in more detail.

[Example 1]
(Sulfide solid electrolyte synthesis)
_{Li 2} S (manufactured by Furuuchi Chemicals), P ₂ S ₅ (manufactured by Aldrich) and Li I (manufactured by Nippoh Chemicals) so as to have a molar ratio of _{30 LiI · 70 (0.75 Li 2} S · 0.25 P ₂ S _5). Weighed in and mixed in an agate mortar for 5 minutes. Dehydrated heptane (manufactured by Kanto Chemical Industry Co., Ltd.) was added to the obtained mixture, and mechanical milling was performed for 40 hours using a planetary ball mill. Then, heptane was removed by drying to obtain a sulfide solid electrolyte.

(Introduction of ionic liquid into the support)
A Li salt (lithium bis (trifluoromethanesulfonyl) imide, LiTFSI) was mixed at a ratio of 0.1 mol with respect to 1 mol of tetraglime (manufactured by Kishida Chemical) to obtain an ionic liquid (solvated ionic liquid). Then, a support (polyimide, pore ratio 43%, average pore diameter 5 μm, thickness 20 μm) was immersed in an ionic liquid and drawn into a vacuum to obtain a support impregnated with the ionic liquid.

(Preparation of solid electrolyte layer)
The synthesized sulfide solid electrolyte was added so as to have a solid content of 40% by weight based on heptane. Further, SBR (styrene butadiene rubber) was added as a binder so as to be 1% by weight based on the sulfide solid electrolyte. Then, it was dispersed by an ultrasonic homogenizer to obtain a slurry. The obtained slurry is applied to both sides of a support impregnated with an ionic liquid and dried to obtain a laminate having a first solid electrolyte portion, a support impregnated with an ionic liquid, and a second solid electrolyte portion. Got The obtained laminate was punched to a size ^{of 1 cm 2} , placed in ^{a 1 cm 2 ceramic mold, and hot-pressed at 1 ton / cm 2} , 160 ° C. for 10 minutes to obtain a solid electrolyte layer.

[Examples 2 to 6]
Ratios of Li salt (lithium bis (trifluoromethanesulfonyl) imide, LiTFSI) to 1 mol of tetraglime (manufactured by Kishida Chemical Co., Ltd.) of 0.8 mol, 1.0 mol, 2.0 mol, 2.5 mol, and 3.0 mol, respectively. A solid electrolyte layer was obtained in the same manner as in Example 1 except that the mixture was mixed in 1.

[Example 7]
A solid electrolyte layer was obtained in the same manner as in Example 3 except that triglime was used instead of tetraglime.

[Example 8]
A solid electrolyte layer was obtained in the same manner as in Example 3 except that a Li salt (lithium bis (fluoromethanesulfonyl) imide, LiFSI) was used instead of LiTFSI.

[Comparative Example 1]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that the support was not impregnated with the ionic liquid.

[Comparative Example 2]
Example 1 except that 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide (EMITFSI) was used instead of tetraglime and LiTFSI was mixed at a ratio of 0.2 mol to 1 mol of EMITFSI. A solid electrolyte layer was obtained in the same manner as above.

[Reference example 1]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that a support impregnated with an ionic liquid was not used.

[Evaluation]
The solid electrolyte layers obtained in Examples 1 to 8, Comparative Examples 1 and 2, and Reference Example 1 were subjected to ionic conductivity measurement by the AC impedance method. For the measurement, a solartron (manufactured by Toyo Corporation) was used, and the impedance was measured under the conditions of an applied voltage of 10 mV, a measurement frequency range of 0.1 to 1 MHz, and 25 ° C. The ionic conductivity of the solid electrolyte layer was calculated based on the resistance value and thickness of the solid electrolyte layer. The results are shown in Table 1.

As shown in Table 1, Examples 1 to 8 had five times or more higher ionic conductivity than Comparative Example 1. In other words, in Comparative Example 1, it was suggested that the inside of the support was not filled with the sulfide solid electrolyte even when hot pressing was performed. In addition, the ionic conductivity of Examples 2 to 5 was significantly higher than that of Example 1. It is presumed that the reason is that in Examples 2 to 5, since the Li salt concentration is higher than that in Example 1, the viscosity of the ionic liquid does not become too low, and the ionic liquid is sufficiently retained in the support. To.

In addition, the ionic conductivity of Examples 2 to 5 was significantly higher than that of Example 6. The reason is that in Examples 2 to 5, since the Li salt concentration is lower than that in Example 6, the decrease in ionic conductivity due to excessive Li salt can be suppressed, and the support is easily impregnated with the ionic liquid. It is presumed that there is. In addition, Examples 7 and 8 showed the same level of ionic conductivity as Examples 2 to 4.

Examples 1 to 8 had higher ionic conductivity than Comparative Example 2. In particular, in Example 1, the Li salt concentration was half that of Comparative Example 2, but the ionic conductivity was 1.5 times or more. In Comparative Example 2, it is presumed that EMITFSI reacted with the sulfide solid electrolyte to reduce the ionic conductivity (increased resistance). On the other hand, in Examples 1 to 8, it is presumed that the solvated ionic liquid did not react with the sulfide solid electrolyte and the ionic conductivity did not decrease.

In addition, the results of the ionic conductivity of Example 3, Comparative Example 1 and Reference Example 1 are shown in FIG. As shown in FIG. 3, the ionic conductivity of Comparative Example 1 is significantly lower than that of Reference Example 1. On the other hand, in Example 3, the decrease in ionic conductivity is suppressed. As described above, it was confirmed that the solid electrolyte layer in which the decrease in ionic conductivity was suppressed could be obtained by filling the pores of the support with the solvated ionic liquid.

1 ... Positive electrode active material layer 2 ... Negative electrode active material layer 3 ... Solid electrolyte layer 4 ... Positive electrode current collector 5 ... Negative electrode current collector 10 ... Solid battery 31 ... First solid electrolyte part 32 ... Second solid electrolyte part 33 ... Support body

Claims (1)

A solid-state battery having a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer arranged between the positive electrode active material layer and the negative electrode active material layer.
The solid electrolyte layer has a first solid electrolyte portion, a support having pores, and a second solid electrolyte portion in this order.
The first solid electrolyte portion contains a first sulfide solid electrolyte containing Li element, P element and S element, and contains
The second solid electrolyte portion contains a disulfide solid electrolyte containing Li element, P element and S element, and contains
A solid-state battery in which the pores of the support are filled with a solvated ionic liquid containing a Li salt and a Lewis base.

Images