Liquid compositions, storage containers, and apparatus and methods for preparing solid electrolyte layers or electrode mixture layers.

Abstract

This invention relates to liquid compositions, storage containers, and apparatus and methods for preparing solid electrolyte layers or electrode mixture layers. A liquid composition is provided comprising a solvent, an inorganic solid electrolyte, and a dispersant. The dispersant is soluble in the solvent. The particle size (D) of a 10% volume fraction of the solid component contained in the liquid composition is specified. 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies D 90 / D 10 >10、D 50 <1μm, and D m <2μm, where D 10 D 50 D 90 and D m It was measured using laser diffraction.

Description

Technical Field

[0001] This disclosure generally relates to liquid compositions, storage containers, and apparatus and methods for preparing solid electrolyte layers or electrode mixture layers. Background Technology

[0002] Electrochemical components such as lithium-ion secondary batteries, lithium-ion capacitors, electrical double-layer capacitors, and redox capacitors are installed in, for example, electronic devices and electric vehicles, and are widely used. In particular, the demand for lithium-ion secondary batteries for vehicles is expected to expand in recent years due to the need to reduce environmental impact. Against this backdrop, there is a need for further improvements in the safety and energy density of lithium-ion secondary batteries, and efforts are actively underway to bring all-solid-state batteries, in which existing electrolyte solutions are replaced by solid electrolytes, into practical application.

[0003] A necessary characteristic of the solid electrolyte layer in all-solid-state batteries is high Li-ion conductivity.

[0004] For example, a technique employing solid electrolyte particles with large average particle size and solid electrolyte particles with small average particle size has been proposed as a technique for providing an all-solid-state battery comprising a solid electrolyte layer with low ion conduction resistance and high packing percentage (see, for example, Japanese Unexamined Patent Application Publication No. 2013-157084).

[0005] The production methods for the solid electrolyte layer of all-solid-state batteries are broadly classified into dry and wet processes. In the dry process, dried solid electrolyte powder particles are deployed into sheets, then pressed and sintered to obtain a sheet-like solid electrolyte layer. In the wet process, a coating method is used to form the electrolyte layer by mixing a liquid composition obtained by mixing the solid electrolyte in a solvent. In terms of productivity, the wet process is preferred.

[0006] Furthermore, in the wet process, the coating method using inkjet printing—which allows for precise coating control and promotes greater and simpler shape freedom for solid-state batteries—is highly effective in meeting future demands for free and efficient production of batteries.

[0007] From the perspective of improving the production efficiency when forming a solid electrolyte layer, it is advisable to prepare a slurry containing a high concentration of solid electrolytes.

[0008] For example, a technique using a specific solvent has been proposed as a means to mitigate the reduction in ionic conductivity of solid electrolytes (see, for example, International Publication No. WO 2016 / 013224). The proposed technique demonstrates that compositions with excellent slurry retention and slurry coatability can also be obtained by using this solvent.

[0009] A solid electrolyte composition comprising: a polymer containing components derived from macromolecular monomers satisfying predetermined conditions; and a dispersion medium is proposed as a technique for leveraging superior dispersibility to, for example, improve the production efficiency of all-solid-state secondary batteries (see, for example, International Publication No. WO 2019 / 054455).

[0010] A technique using solid electrolyte particles with a predetermined particle size has been proposed as a technique for providing, for example, a solid electrolyte that can maintain a slurry state for a certain period of time when mixed in a liquid (see, for example, Japanese Unexamined Patent Application Publication No. 2009-211950).

[0011] Efforts are also being made to suppress the release of hydrogen sulfide and the formation of sulfur oxides during production, for example, by using hydrocarbon solvents with low polarity (see, for example, Japanese Unexamined Patent Application Publication No. 2012-212652). Summary of the Invention

[0012] In one embodiment, the liquid composition comprises a solvent, an inorganic solid electrolyte, and a dispersant. The dispersant is soluble in the solvent. The particle size (D) of the solid component comprising 10% by volume in the liquid composition is... 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and mode diameter (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It was measured using laser diffraction.

[0013] D 90 / D 10 >10---Equation (1)

[0014] D 50 <1μm---Equation (2)

[0015] D m <2μm---Equation (3) Attached Figure Description

[0016] Figure 1 This is an exemplary view illustrating an instance of a device configured to prepare a solid electrolyte layer or electrode mixture layer to implement a method for preparing a solid electrolyte or electrode mixture of this disclosure;

[0017] Figure 2This is an exemplary view illustrating another example of a device (liquid discharge device) configured to prepare a solid electrolyte layer or electrode mixture layer, to implement a method for preparing the solid electrolyte layer and electrode mixture layer of this disclosure; and

[0018] Figure 3 This is an exemplary view of an example energy storage element instance, which includes a solid electrolyte layer of this disclosure. Detailed Implementation

[0019] In the following description, embodiments of the invention will be described with reference to the accompanying drawings.

[0020] (Liquid composition)

[0021] One embodiment of the liquid composition disclosed herein is a liquid composition comprising a solvent, an inorganic solid electrolyte, and a dispersant, and further comprising other components as desired, wherein the dispersant is soluble in the solvent, and the particle size (D) of the solid component comprising 10% by volume of the liquid composition is... 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m The measurement was performed using laser diffraction (hereinafter, this embodiment may be referred to as the "first embodiment"). Another embodiment of the liquid composition disclosed herein is a liquid composition for ejection using an inkjet head, comprising a solvent, an inorganic solid electrolyte, and a dispersant, and further comprising other components as desired, wherein the dispersant is soluble in the solvent, and the particle size (D) of the solid component comprising 10% by volume of the liquid composition is... 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It is measured by laser diffraction (hereinafter, this embodiment may be referred to as the "second embodiment").

[0022] D 90 / D 10 >10---Equation (1)

[0023] D 50<1μm---Equation (2)

[0024] D m <2μm---Equation (3)

[0025] According to this disclosure, one object is to provide a liquid composition having good inkjet ejection properties, and to obtain a solid electrolyte layer having good ionic conductivity using the liquid composition.

[0026] According to this disclosure, a liquid composition can be provided that has good inkjet ejection properties, and a solid electrolyte layer with good ionic conductivity can be obtained using the liquid composition.

[0027] As mentioned above, a necessary characteristic of the solid electrolyte layer in an all-solid-state battery is high Li-ion conductivity.

[0028] In terms of productivity, wet coating methods, such as those using a die coater or a comma coater, are preferred for preparing the solid electrolyte layer. In terms of on-demand performance, forming the solid electrolyte by inkjet ejection using a liquid ejection device is considered preferred.

[0029] However, obtaining a liquid composition that maintains good inkjet ejection properties and allows for the acquisition of a solid electrolyte layer with good ionic conductivity is extremely difficult. For example, using large-particle-size solid electrolyte material in the liquid composition is advantageous because it mitigates grain boundary resistance and maintains good ionic conductivity, but it results in poor inkjet ejection properties. On the other hand, using small-particle-size solid electrolyte material in the liquid composition achieves stable inkjet ejection, but it leads to high grain boundary resistance—due to the presence of numerous grain boundaries—and low ionic conductivity.

[0030] The inventors have discovered that a liquid composition containing a solvent, an inorganic solid electrolyte (hereinafter referred to as "ionic conductive material"), and a dispersant is suitable as a liquid composition in which the dispersant, when soluble in the solvent, exhibits good inkjet ejection properties and, when used therein, a solid electrolyte layer with good ionic conductivity can be obtained, and the particle size (D) of the 10% volume fraction of the solid component contained in the liquid composition is... 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It was measured using laser diffraction.

[0031] D 90 / D 10 >10---Equation (1)

[0032] D 50 <1μm---Equation (2)

[0033] D m <2μm---Equation (3)

[0034] This is explained for the following reasons.

[0035] The actual powder particle filling state obtained when a liquid composition is dried is considered to be a random particle filling state. For the ideal, most compact filling state, where the gaps between large particles are filled by smaller particles, it is necessary to fill the gaps between large particles with smaller particles. This state is difficult to achieve through random filling, which introduces defects as a side effect, such as defects at locations where large particles are not present, and consequently reduces ionic conductivity. To increase the filling rate, it is necessary to apply pressure at extremely high pressures above 100 MPa.

[0036] In this case, it was found that the filling rate in the solid electrolyte layer formed from the dried powder obtained from the liquid composition was actually improved, and good results were obtained in terms of ionic conductivity when there were particles with a continuous and wide variation in particle size and many small particles, contrary to the ideal filling state.

[0037] Another embodiment of the liquid composition disclosed herein is a liquid composition comprising a solvent, an inorganic solid electrolyte, and a dispersant, and further comprising other components as needed, wherein the solvent is at least one selected from (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters, wherein the (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters have a vapor pressure of 0.1 hPa or more and 1.0 hPa or less at 25°C (hereinafter, this embodiment may be referred to as the "Third Embodiment"). Yet another embodiment of the liquid composition disclosed herein is a liquid composition ejected via an inkjet head, comprising a solvent, an inorganic solid electrolyte, and a dispersant, and further comprising other components as needed, wherein the solvent is at least one selected from (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters, wherein the (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters have a vapor pressure of 0.1 hPa or more and 1.0 hPa or less at 25°C (hereinafter, this embodiment may be referred to as the "Fourth Embodiment").

[0038] According to this disclosure, one object is to provide a liquid composition that can suppress the release of hydrogen sulfide and improve the dispersibility of the inorganic solid electrolyte even when containing a high concentration of inorganic solid electrolyte, and can be discharged by an inkjet method.

[0039] According to this disclosure, a liquid composition can be provided that can suppress the release of hydrogen sulfide and improve the dispersibility of the inorganic solid electrolyte even when it contains a high concentration of inorganic solid electrolyte, and can be discharged by an inkjet method.

[0040] As mentioned above, wet coating is preferred as a method for preparing the solid electrolyte layer in all-solid-state batteries in terms of productivity. However, inorganic solid electrolytes, especially sulfide solid electrolytes containing elemental sulfur, react not only with water but also with organic solvents, releasing harmful hydrogen sulfide. Therefore, there are limitations on the solvents suitable for wet coating.

[0041] From the perspective of improving production efficiency in forming a solid electrolyte layer, it is possible to prepare a slurry containing a high concentration of inorganic solid electrolytes. However, in liquid compositions containing a high concentration of inorganic solid electrolytes, flocculation of the inorganic solid electrolytes is prone to occur, or the liquid composition is very thick.

[0042] Existing technologies have been studied in various ways as described above, but have almost never succeeded in suppressing flocculation, maintaining dispersibility, and exhibiting inkjet ejection performance—even at high concentrations of inorganic solid electrolytes (hereinafter referred to as “ionic conductive materials”).

[0043] Another problem exists. Some solvents—inks containing these solvents can be ejected by inkjet printers—cause ink to dry and clog the ejection unit when the ink is ejected again after it has stopped for a while.

[0044] The inventors have discovered that a liquid composition containing a solvent, an inorganic solid electrolyte, and a dispersant is suitable for use such that when the liquid composition contains at least one selected from (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters as a solvent, it can be ejected by an inkjet method, wherein the (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters have a vapor pressure of 0.1 hPa or more and 1.0 hPa or less at 25°C, so that the liquid composition can suppress the release of hydrogen sulfide and the flocculation of the inorganic solid electrolyte, and can have improved dispersibility even when the liquid composition contains a high concentration of the inorganic solid electrolyte.

[0045] In this specification, "liquid composition that can be ejected by inkjet method" refers to a liquid composition that can be continuously ejected for more than 60 seconds from one nozzle (40 μm diameter) of the inkjet head of the EV1000 droplet observer (available from Ricoh Co., Ltd.). When it is stated that the liquid composition can be continuously ejected for more than 60 seconds, the ejection volume of the liquid composition is not a problem, as long as the liquid composition continues to be ejected for at least 60 seconds after it begins to be ejected. That is, as long as the liquid composition can be continuously ejected for at least 60 seconds from the start of ejection, the ejection volume of the liquid composition can be varied within the time period from the start of ejection to 60 seconds after the start of ejection, or it does not necessarily need to be varied.

[0046] In this specification, a liquid composition that can be re-ejected by inkjet means a liquid composition that can be successfully re-ejected when it has been ejected from a nozzle (40 μm diameter) of the inkjet head of the EV1000 droplet observer (available from Ricoh Co., Ltd.), remains in the ejected state for 60 seconds, and then remains in a static state for 5 minutes.

[0047] Solvent

[0048] The solvents used in the first and second embodiments are not particularly limited and can be appropriately selected according to the intended purpose. The preferred solvent is at least one selected from (I) aliphatic hydrocarbons, (II) monoethers and (III) branched esters, wherein the (I) aliphatic hydrocarbons, (II) monoethers and (III) branched esters have a vapor pressure of 0.1 hPa or more and 1.0 hPa or less at 25°C.

[0049] The solvents in the third and fourth embodiments are at least one selected from (I) aliphatic hydrocarbons, (II) monoethers and (III) branched esters, wherein the (I) aliphatic hydrocarbons, (II) monoethers and (III) branched esters have a vapor pressure of 0.1 hPa or more and 1.0 hPa or less at 25°C.

[0050] Liquid compositions containing solvents having a vapor pressure of 0.1 hPa or higher and 1.0 hPa or lower at 25°C exhibit sufficiently low evaporability. Therefore, clogging of the ejection port due to drying of the liquid composition during inkjet ejection can be suppressed. When the liquid composition is prepared using at least one selected from (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters, the degradation of inorganic solid electrolytes can be suppressed, and particle flocculation can be suppressed with high dispersibility.

[0051] One or more solvents having a vapor pressure of 0.1 hPa or higher and 1.0 hPa or lower at 25°C may be used alone or in combination. When using a mixed solvent of two or more solvents, evaluate whether the vapor pressure of each solvent at 25°C is 0.1 hPa or higher and 1.0 hPa or lower.

[0052] For information on the vapor pressure of a solvent at 25°C, refer to the solvent's Safety Data Sheet (SDS) if the relevant vapor pressure is listed in the SDS. For solvents whose vapor pressure at 25°C is not listed in their SDS, the vapor pressure at 25°C can be measured using an isotenascope as described in the article "Environment Agency, Environmental Health Department, Office of Health Studies, Studies into Physicochemical Characterization of Chemical Substances, Japan Environment Association, 1986".

[0053] There are no particular limitations on the vapor pressure of the solvent at 25°C, which can be appropriately selected according to the intended purpose, and it is preferably 0.1 hPa or more and 1.0 hPa or less, and more preferably 0.1 hPa or more and 0.5 hPa or less in order to prevent drying.

[0054] [(I) Aliphatic hydrocarbons]

[0055] (I) indicates a solvent with an aliphatic hydrocarbon structure. Structurally, aliphatic hydrocarbons exhibit sufficiently low reactivity with sulfide solid electrolytes. Therefore, aliphatic hydrocarbons have almost no effect on ionic conductivity after coating.

[0056] Aliphatic hydrocarbons may or may not have branches.

[0057] (I) There is no particular limitation on the number of carbon atoms in the aliphatic hydrocarbon, which can be appropriately selected according to the intended purpose, and is preferably in the range of 11 to 14. When the number of carbon atoms is within the preferred range, the occurrence of (inkjet) head clogging caused by drying during the inkjet coating process can be suppressed, and the occurrence of clogging in the inkjet step is also suppressed due to the low viscosity of the solvent.

[0058] (I) Preferred examples of aliphatic hydrocarbons include undecane, dodecane, tridecane, tetradecane, cycloundecane, cyclododecane, cyclotridecane, cyclotetradecane, and 2-butyloctane. Undecane, tridecane, tetradecane, and 2-butyloctane are more preferred.

[0059] [(II) Monoether]

[0060] (II) indicates solvents with a monoether structure. Diether structures and higher ether structures are highly reactive with sulfide solid electrolytes, and stable inks may not be obtained with these solvents.

[0061] The number of molecules constituting the basic skeleton of (II) monoether is not particularly limited and can be appropriately selected according to the intended purpose, preferably in the range of 11 to 13. When the number of molecules is within the preferred range, it is possible to suppress the occurrence of (inkjet) head clogging caused by drying during the inkjet coating process, and because the boiling point of the solvent is not higher than 250°C, it is possible to suppress excessive energy consumption in the drying step after inkjet printing.

[0062] (II) Preferred examples of monoethers include butylphenyl ether, pentylphenyl ether, hexylphenyl ether, dipentyl ether, and dihexyl ether. Butylphenyl ether and dihexyl ether are more preferred.

[0063] [(III) Branched esters]

[0064] (III) indicates a solvent with a branched ester structure.

[0065] As (III) branched esters, type (i) esters and type (ii) esters are preferred. In type (ii) esters, a hydrocarbon group containing 2 or fewer carbon atoms is attached to the carbon side of the ester group and a branched hydrocarbon group is attached to the oxygen side of the ester group; in type (ii) esters, a hydrocarbon group containing 3 or fewer carbon atoms is attached to the oxygen side of the ester group and a branched hydrocarbon group is attached to the carbon side of the ester group.

[0066] (i) Type esters contain a hydrocarbon group (i.e., methyl or ethyl) with two or fewer carbon atoms as the group bonded to the carbon atom of the ester group. Due to the small compound size of this type of ester and the ability to moderate viscosity to a sufficiently low level, good inkjet ejection properties can be achieved. Furthermore, (i) type esters contain a branched group as the group bonded to the oxygen atom of the ester group. Because this ester group (whose reactivity is moderated due to steric hindrance) does not react with inorganic solid electrolytes, a stable solid electrolyte membrane can be provided.

[0067] In type (i) esters, branched hydrocarbon groups containing three or more carbon atoms are preferably used as groups that bind to the oxygen of the ester group.

[0068] (ii) Type esters contain a hydrocarbon group with three or fewer carbon atoms as the group bonded to the oxygen atom of the ester group. Due to the small compound size of this type of ester and the ability to moderate viscosity to a sufficiently low level, good inkjet ejection properties can be achieved. Furthermore, (ii) type esters contain a branched group as the group bonded to the carbon atom of the ester group. Because this ester group (whose reactivity is moderated due to steric hindrance) does not react with inorganic solid electrolytes, a stable solid electrolyte membrane can be provided.

[0069] The carbon side of the ester group (or the group bonded to the carbon of the ester group) represents "R" in formula (A). The oxygen side of the ester group (or the group bonded to the oxygen of the ester group) represents "R'" in formula (A).

[0070]

[0071] (III) Preferred examples of branched esters include isooctyl acetate, 2-ethylhexyl acetate, 2-nonyl acetate, and 2-ethylhexyl propionate. 2-nonyl acetate, 2-ethylhexyl acetate, and 2-ethylhexyl propionate are more preferred.

[0072] As a solvent, one or a mixture of two or more solvents having structures selected from (I), (II) and (III) above can be used.

[0073] There are no particular restrictions on the mass ratio between two or more solvents used in combination, and they can be appropriately selected according to the intended purpose.

[0074] As the solvent in the first to fourth embodiments, a solvent having a relative permittivity of 6.0 or less at 25°C is preferred. When the solvent is preferred, there is an advantage that the inorganic solid electrolyte can be highly dispersible in the solvent, regardless of whether the inorganic solid electrolyte is an inorganic solid electrolyte containing elemental sulfur or an inorganic solid electrolyte containing elemental oxygen. When the preferred solvent is used in combination with an inorganic solid electrolyte containing elemental sulfur, there is an advantage that the possibility of reaction between the solvent and the inorganic solid electrolyte containing elemental sulfur is low, thereby suppressing the release of harmful hydrogen sulfide. A single preferred solvent can be used alone, or two or more preferred solvents can be used in combination. When a mixed solvent of two or more solvents is used, the relative permittivity of the mixed solvent is preferably 6.0 or less.

[0075] There are no particular limitations on the methods used to measure the relative permittivity of a solvent, and they can be appropriately selected according to the intended purpose. For example, the relative permittivity of a solvent can be measured at 10 kHz using a double cylindrical tube with a MODEL 871 (available from Sanyo Trading Co., Ltd.) as a current measurement method.

[0076] Specific examples of solvents with a relative permittivity of 6.0 or less at 25°C include pentane, isopentane, hexane, heptane, 2,2-dimethylbutane, octane, cyclohexane, tetradecane, 1,4-dioxane, benzene, xylene, carbon tetrachloride, mesitylene, toluene, dibutyl ether, anisole, 1,2-diethoxyethane, 2-methyl anisole, 3-methyl anisole, 4-methyl anisole, 1,2-methoxybenzene, 1,3-methoxybenzene, p-ethylaniline, 4-octanol, phenethyl ether, 2-ethylhexyl acetate, butylphenyl ether, isopropylbenzene, 1,2,3,4-tetrahydronaphthalene, ethyl decanoate, isobutyl acetate, diisopentyl ether, tridecane, cyclooctane, and ethyl propionate.

[0077] As a solvent, a dehydrating solvent is preferred. There are no particular limitations on the degree of dehydration, and it can be appropriately selected according to the intended purpose. The solvent water content, as measured using a Karl Fischer moisture titrator, is preferably below 1000 ppm, more preferably below 100 ppm, and even more preferably below 10 ppm.

[0078] Inorganic solid electrolytes

[0079] The inorganic solid electrolytes in the first to fourth embodiments are not particularly limited, as long as the inorganic solid electrolyte has ionic conductivity rather than electronic conductivity. Among the inorganic solid electrolytes, sulfide solid electrolytes containing elemental sulfur or oxide solid electrolytes containing elemental oxygen as an anion are preferred in terms of ionic conductivity. Sulfide solid electrolytes are preferred due to their high plasticity, which allows for the formation of good interfaces between solid electrolyte particles or between the solid electrolyte and the active material. Depending on the need, one such inorganic solid electrolyte or two or more such organic solid electrolytes may be used.

[0080] --Sulfide solid electrolyte--

[0081] As a sulfide inorganic solid electrolyte, compounds containing sulfur atoms (S), possessing ionic conductivity belonging to Group I or II metals of the periodic table, and having electronic insulation properties are preferred.

[0082] Sulfide solid electrolytes can be broadly classified into crystalline sulfide solid electrolytes and glassy solid electrolytes.

[0083] There are no particular limitations on crystalline sulfide solid electrolytes, and they can be appropriately selected according to the intended purpose. Examples of crystalline sulfide solid electrolytes include Li. 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 9.6 P3S12 Li9P3S9O3, Li 9.81 Sn 0.81 P 2.19 S 12 Li 9.42 Si 1.02 P 2.1 S 9.96 O 2.04 Li 10 Ge(P 1-x Sb x )2S 12 (0≤x≤0.15), Li 10 SnP2S 12 Li 10.35 [M1 1-x M2 x ] 1.35 P 1.65 S 12 (where M1 and M2 represent any one of Si, Ge, Sn, As, and Sb, 0 ≤ x ≤ 0.15), Li 11 Si2PS 12 Li 11 AlP2S 12 Li 3.45 Si 0.45 P 0.55 S4, Li6PS5X (where X represents any one of Cl, Br, and I), Li5PS4X2 (where X represents any one of Cl, Br, and I), Li 5.5 PS 4.5 Cl 1.5 Li 5.35 Ca 0.1 PS 4.5 Cl 1.55 Li 6+ x M x Sb 1-x S5I (where M represents any of Si, Ge, and Sn, 0≤x≤1), Li7P2S8I, γ-Li3PS4, Li4MS4 (where M represents any of Ge, Sn, and As), Li 4-x Sn 1-x Sb x S4(0≤x≤0.15), Li 4-x Ge 1-x P x S4(0≤x≤0.15) and Li 3+5x P 1-x S4(0≤x≤0.3).

[0084] There are no particular limitations on glassy sulfide solid electrolytes, and they can be appropriately selected according to the intended purpose. Examples of glassy sulfide solid electrolytes include Li₂S-P₂S₅, Li₂S-P₂S₅-LiI, Li₂S-P₂S₅-P₂O₅, Li₂S-P₂S₅-LiCl, Li₂S-SiS₂, Li₂S-SiS₂-P₂S₅, Li₂S-SiS₂-Al₂S₃, and Li₂S-SiS₂-Li x MO y (Where M represents any of Si, P, and Ge). Alternatively, for example, Li7P3S can also be used. 11 Glass-ceramics are partially crystalline, glassy sulfide solid electrolytes. There are no specific requirements for the mixing ratio between glassy sulfide solid electrolyte materials.

[0085] --Oxide Solid Electrolytes--

[0086] As an oxide inorganic solid electrolyte, any compound containing elemental oxygen (O), having ionic conductivity belonging to Group I or II of the periodic table, and having electronic insulation is preferred.

[0087] Oxide solid electrolytes can be broadly classified into crystalline oxide solid electrolytes and glassy oxide solid electrolytes.

[0088] There are no particular limitations on crystalline oxide solid electrolytes, and they can be appropriately selected according to the intended purpose. Examples of crystalline oxide solid electrolytes include Li. 1+x M x Ti 2-x (PO4)3 (where M represents any one of Al, Cr, Ga, Fe, Sc, In, Lu, Y, and La, 0 ≤ x ≤ 0.5), La x Li y TiO3 (0.3≤x≤0.7, 0.3≤y≤0.7) and Li 7-x La3Zr 2-x M x O 12 (where M represents Nb or Ta, 0≤x≤1).

[0089] There are no particular limitations on glassy oxide solid electrolytes, and they can be appropriately selected according to the intended purpose. Examples of glassy oxide solid electrolytes include Li4SiO4-Li2BO3, Li3BO3-Li2SO4, Li2O-B2O3-P2O5, and Li2O-SiO2.

[0090] As an inorganic solid electrolyte, products prepared by known methods or commercially available products can be used.

[0091] The content of the inorganic solid electrolyte in the liquid composition is not particularly limited and can be appropriately selected according to the intended purpose. The solid concentration of the inorganic solid electrolyte is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more. There is no particular upper limit, and it can be appropriately selected according to the intended purpose, and is preferably 60% by mass or less. When the content of the inorganic solid electrolyte is within the above-mentioned preferred range, it has the advantage of obtaining superior productivity.

[0092] <Dispersant>

[0093] The dispersant used in the first and second embodiments is not particularly limited, as long as it is soluble in the solvent, does not readily react with the inorganic solid electrolyte, and is capable of dispersing the inorganic solid electrolyte. Known or commercially available dispersants can be appropriately selected according to the intended purpose. A single dispersant can be used, or two or more dispersants can be used in combination.

[0094] The dispersant used in the third and fourth embodiments is not particularly limited, as long as the dispersant does not readily react with the inorganic solid electrolyte and is capable of dispersing the inorganic solid electrolyte. Known or commercially available dispersants can be appropriately selected according to the intended purpose. A single dispersant can be used, or two or more dispersants can be used in combination.

[0095] The dispersants in the preferred third and fourth embodiments are soluble in solvents.

[0096] In this specification, solvent-soluble dispersant means a dispersant that is compatible with the solvent. More specifically, a dispersant is considered to be dissolved in the solvent when a dispersant (3% by mass) is added to and dissolved in a solvent and then left to stand for 10 minutes without observing precipitation or supernatant.

[0097] Specific examples of dispersants include: polyethylene-based, polyethylene oxide-based, polypropylene oxide-based, polycarboxylic acid-based, naphthalene sulfonic acid formalin condensate-based, polyethylene glycol-based, polycarboxylic acid alkyl ester-based, polyether-based, polyethyleneimine-based, and polyalkylene polyamine-based high molecular weight dispersants; alkyl sulfonic acid-based, quaternary ammonium-based long-chain alcohol alkylene oxide-based, polyol ester-based, and alkyl polyamine-based low molecular weight dispersants; and inorganic dispersants such as polyphosphate dispersants.

[0098] There are no particular limitations on the content of the dispersant in the liquid composition, and it can be appropriately selected according to the intended purpose. The solid concentration of the dispersant is preferably 10% by mass or less, and more preferably 3% by mass or less, relative to the solid electrolyte dispersed by the dispersant. When the content of the dispersant is outside the above-mentioned preferred range, there is a risk of flocculation due to high dispersant concentration.

[0099] <Other Components>

[0100] Other components in the liquid compositions according to the first to fourth embodiments are not particularly limited and can be appropriately selected according to the intended purpose, provided that the effects of this disclosure are not compromised. Examples of other components include known components used in solid electrolyte layers or electrode mixture layers. Specific examples of other components include binders, active materials, and conductive additives. One of these other components can be used alone, or two or more of these other components can be used in combination.

[0101] There are no particular restrictions on the content of other components in the liquid composition, and they can be appropriately selected according to the intended purpose.

[0102] -Adhesive-

[0103] There are no particular limitations on the adhesive, and it can be appropriately selected according to the intended purpose, as long as the adhesive enables the inorganic solid electrolytes to bond together, or to bond the inorganic solid electrolytes to the base or electrode active material. Examples of adhesives include high molecular weight compounds and high molecular weight particles. One adhesive may be used alone, or two or more adhesives may be used in combination.

[0104] There are no particular limitations on high molecular weight compounds, and they can be appropriately selected according to the intended purpose. Examples of high molecular weight compounds include polyamide compounds, polyimide compounds, polyamide-imide, ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), isoprene rubber, polyisobutylene, polyethylene glycol (PEO), polymethyl methacrylate (PMMA), and polyvinyl acetate (PEVA).

[0105] High molecular weight particles can be used as high molecular weight compounds that can be dispersed in liquids. The maximum particle size of the high molecular weight particles can be any size, as long as it is smaller than the nozzle diameter of the liquid discharge head. The modal diameter of the high molecular weight particles is preferably 0.01 μm to 1 μm. Examples of materials constituting high molecular weight particles include thermoplastic resins such as polyvinylidene fluoride, acrylic resins, styrene-butadiene rubber, polyethylene, polypropylene, polyurethane, nylon, polytetrafluoroethylene, polyphenylene sulfide, polyethylene terephthalate, and polybutylene terephthalate.

[0106] -Active Substances-

[0107] As an active material, either a positive electrode active material or a negative electrode active material suitable for electrochemical elements can be used.

[0108] There are no particular restrictions on the positive electrode active material, as long as it can reversibly absorb and release alkali metal ions. Transition metal compounds containing alkali metals can be used as positive electrode active materials.

[0109] Examples of transition metal compounds containing alkali metals include lithium-containing transition metal compounds, such as complex oxides containing lithium and one or more elements selected from cobalt, manganese, nickel, chromium, iron and vanadium.

[0110] Examples of lithium-containing transition metal compounds include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, and lithium nickel cobalt oxide.

[0111] As transition metal compounds containing alkali metals, polyanionic compounds containing XO4 tetrahedra (e.g., X = P, S, As, Mo, W, or Si) in their crystal structure can also be used. Among these polyanionic compounds, lithium-containing transition metal phosphate compounds such as lithium iron phosphate and lithium vanadium phosphate are preferred in terms of cycling characteristics, and lithium vanadium phosphate is particularly preferred in terms of lithium diffusion coefficient and input / output characteristics of electrochemical elements.

[0112] In terms of electronic conductivity, polyanionic compounds are preferred composite materials whose surfaces are coated with conductive additives such as carbon materials.

[0113] There are no particular restrictions on the negative electrode active material, as long as it can reversibly absorb and release alkali metal ions. Carbon materials containing graphite with a graphite crystal structure can be used as negative electrode active materials.

[0114] Examples of carbon materials include natural graphite, artificial graphite, hard carbon (difficult to graphitize), and soft carbon (easy to graphitize).

[0115] Examples of carbon materials include natural graphite, artificial graphite, hard carbon (difficult to graphitize), and soft carbon (easy to graphitize).

[0116] In terms of energy density of electrochemical elements, high-capacity materials such as lithium metal, silicon, tin, silicon alloys, tin alloys, silicon oxide, silicon nitride, and tin oxide are preferred as negative electrode active materials.

[0117] The content of the active material in the liquid composition is not particularly limited and can be appropriately selected according to the intended purpose, preferably 10% by mass or more, and more preferably 15% by mass or more. When the content of the active material in the liquid composition is 10% by mass or more, an electrode mixture layer having a predetermined unit weight can be formed by fewer printing passes.

[0118] -Conductive additives-

[0119] There are no particular restrictions on conductive additives, and they can be appropriately selected according to the intended purpose. For example, carbon materials such as conductive carbon black, carbon nanofibers, carbon nanotubes, graphene, and graphite particles can be used.

[0120] Conductive additives can be composite materials combined with active substances.

[0121] Conductive carbon black can be prepared by, for example, furnace method, acetylene method and gasification method.

[0122] As a conductive additive other than carbon materials, metal particles and metal fibers, such as aluminum particles and metal fibers, can be used.

[0123] There is no particular limitation on the amount of conductive additive relative to the active material, and it can be appropriately selected according to the intended purpose, preferably 10% by mass or less, and more preferably 8% by mass or less.

[0124] [Particle size and particle size distribution]

[0125] The particle size (D) of a 10% volume fraction component of solids (such as solid electrolytes and other solid components added as needed) contained in the liquid composition according to the first and second embodiments. 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It was measured using laser diffraction.

[0126] Preferably, the particle size (D) of the 10% volume fraction of solid components (such as solid electrolytes and other solid components added as needed) included in the liquid composition according to the third and fourth embodiments is specified. 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It was measured using laser diffraction.

[0127] When the following formulas (1) to (3) are satisfied, the dried product obtained from the liquid composition has good ionic conductivity.

[0128] D 90 / D 10 >10---Equation (1)

[0129] D 50 <1μm---Equation (2)

[0130] D m <2μm---Equation (3)

[0131] D 90 / D 10 There are no particular restrictions on the value, which can be appropriately selected according to the intended purpose, and it is preferred to be greater than 10, and more preferably 15 or more for better ionic conductivity, and even more preferably 20 or more.

[0132] D 10 The value is not particularly limited and can be appropriately selected according to the intended purpose. It is preferably a value that satisfies the above formula (1), and for good ionic conductivity, it is more preferably 1 μm or less, and even more preferably 0.5 μm or less. D 10 There is no particular limitation on the lower limit of the value, which can be appropriately selected according to the intended purpose, and preferably above 0.05 μm.

[0133] D 90 The value is not particularly limited and can be appropriately selected according to the intended purpose. It is preferably a value that satisfies the above formula (1), and for good ionic conductivity, it is more preferably 2 μm or more, and even more preferably 4 μm or more. D 90 There is no particular upper limit to the value; it can be appropriately selected according to the intended purpose, and preferably below 10 μm.

[0134] D 50 The value is not particularly limited and can be appropriately selected according to the intended purpose, and is preferably a value that satisfies the above formula (2), and is more preferably below 1.0 μm for better ionic conductivity. 50 There is no particular limitation on the lower limit of the value, which can be appropriately selected according to the intended purpose, and preferably above 0.5 μm.

[0135] D m The value is not particularly limited and can be appropriately selected according to the intended purpose, and is preferably a value that satisfies the above formula (3), and is more preferably 2 μm or less for better ionic conductivity, and even more preferably 1.5 μm or less. D m There is no particular limitation on the lower limit of the value, which can be appropriately selected according to the intended purpose, and preferably above 0.5 μm.

[0136] [Maximum particle size]

[0137] The maximum particle size of the solids contained in the liquid composition according to the first to fourth embodiments is not particularly limited, and can be appropriately selected according to the intended purpose, as long as the effects of this disclosure are not compromised. Preferably, the maximum particle size of the solids is smaller than the nozzle diameter of the inkjet head. Preferably, the maximum particle size of the solids is sufficiently smaller than the nozzle diameter of the inkjet head, because better ink ejection performance is obtained. Specifically, the ratio of the maximum particle size of the solids contained in the liquid composition to the nozzle diameter of the inkjet head (maximum particle size of the solids contained in the liquid composition / nozzle diameter of the inkjet head) is preferably 0.8 or less, more preferably 0.6 or less, and even more preferably 0.5 or less. That is, assuming the nozzle diameter of the inkjet head is 40 μm, the maximum particle size of the solids contained in the liquid composition is preferably 32 μm or less, more preferably 24 μm or less, and even more preferably 20 μm or less.

[0138] Used to measure the diameter D of solids contained in a liquid composition. 10 D 50 D 90 and D m There are no particular limitations on the method for determining the maximum particle size, and it can be appropriately selected according to the intended purpose. For example, the diameter D of a solid can be measured according to, for example, ISO 13320. 10 D 50 D 90 and D m And the maximum particle size. There are no particular restrictions on the instrument used for measurement, and it can be appropriately selected according to the intended purpose. An example of an instrument is the laser diffraction / scattering particle size distribution analyzer (LA-960, available from Horiba, Ltd.).

[0139] There are no particular limitations on the methods used to measure the maximum particle size of powder components used as materials in liquid compositions, and they can be appropriately selected according to the intended purpose. Examples of methods include methods using laser diffraction, such as the method described above for measuring the maximum particle size of solids contained in a liquid composition, and methods for obtaining the maximum particle size of powder components from images acquired by scanning electron beam diffraction.

[0140] [Viscosity]

[0141] The viscosity of the liquid composition according to the first to fourth embodiments is not particularly limited and can be appropriately selected according to the intended purpose, provided that the effects of this disclosure are not compromised, and preferably is a viscosity at which the liquid composition can be discharged from the nozzle of the inkjet head. More specifically, the viscosity of the liquid composition at 25°C is preferably 200 mPa·s or less, more preferably 100 mPa·s or less, even more preferably 50 mPa·s or less, and particularly preferably 25 mPa·s or less. The lower limit is not particularly limited and can be appropriately selected within the viscosity range at which the liquid composition can be discharged by inkjet method.

[0142] There are no particular limitations on the method used to measure the viscosity of a liquid composition, and it can be appropriately selected according to the intended purpose. For example, viscosity can be measured using a Type B viscometer (cone-plate viscometer) equipped with a CPA-40Z rotor. In this specification, the viscosity of the liquid composition is expressed at 25°C.

[0143] There are no particular limitations on the use of the liquid composition, and it can be appropriately selected according to the intended purpose. The liquid composition can be used as a material for the solid electrolyte layer of an all-solid-state secondary battery, or as a part of the material involved in forming the electrode mixture layer.

[0144] (Method for preparing liquid compositions)

[0145] There are no particular limitations on the methods used to prepare liquid compositions, and they can be appropriately selected according to the intended purpose. For example, liquid compositions can be appropriately prepared by the following preparation methods.

[0146] The method for preparing the liquid composition is a method for preparing the liquid composition according to the present disclosure, including a dissolution or dispersion step, and may further include other steps as needed.

[0147] <Dissolution or Dispersion Steps>

[0148] The dissolution or dispersion step is the process of dissolving or dispersing an inorganic solid electrolyte and a dispersant in a solvent. For example, a liquid composition can be prepared by adding an inorganic solid electrolyte and a dispersant, along with other components as needed, and mixing the resulting product to a solvent.

[0149] The solvent, inorganic solid electrolyte, and dispersant are the same as those specified in the liquid composition section above.

[0150] There are no particular limitations on the mixing unit, and it can be appropriately selected according to the intended purpose. Examples of mixing units include ultrasonic homogenizers. There are no particular limitations on the mixing conditions, and they can be appropriately selected according to the intended purpose.

[0151] <Other Steps>

[0152] Other steps are not particularly limited and may be appropriately selected according to the intended purpose, provided that the effects of this disclosure are not compromised. Examples of other steps include adjustment steps.

[0153] -Adjustment Steps-

[0154] The conditioning step is a step of adjusting the particle size of the solids contained in the liquid composition by means of mechanical methods.

[0155] There are no particular limitations on the mechanical methods, and they can be appropriately selected according to the intended purpose. Examples of methods include high-speed rotary homogenizers, wet-type jet mills, wet-type bead mills, and combinations of two or more of these. There are no particular limitations on the conditions of the mechanical methods, and they can be appropriately selected according to the intended purpose.

[0156] The conditioning step can be performed during or after the dissolution or dispersion step.

[0157] By adjusting the formula, the solid contained in the liquid composition can satisfy the above formulas (1) to (3). Instead of performing the adjustment step, the dissolution or dispersion step can be performed by using a solid that satisfies the above formulas (1) to (3) as the solid contained in the liquid composition.

[0158] (Storage container)

[0159] The storage container disclosed herein is a storage container in which the liquid composition described above is stored.

[0160] There are no particular restrictions on the shape, structure, and size of the storage containers, and they can be appropriately selected according to the intended purpose.

[0161] (Apparatus configured to prepare a solid electrolyte layer or electrode mixture layer, and a method for preparing a solid electrolyte layer or electrode mixture layer)

[0162] The apparatus configured to prepare the solid electrolyte layer or electrode mixture layer of the present disclosure includes the storage container described above, and a discharge unit configured to discharge the liquid composition stored in the storage container using an inkjet head, and may also include other components as needed.

[0163] The method for preparing the solid electrolyte layer or electrode mixture layer of the present disclosure includes a discharge step of discharging the liquid composition of the present disclosure using an inkjet head, and may further include other steps as needed.

[0164] <Discharge Unit and Discharge Procedure>

[0165] The discharge unit is a unit configured to discharge a liquid composition stored in a storage container using an inkjet head.

[0166] The ejection step is the step of ejecting the liquid composition using an inkjet head.

[0167] By effluent, the liquid composition can be applied to the target and form a liquid composition layer.

[0168] There are no particular restrictions on the target (hereinafter referred to as the "exhaustion target"), and it can be appropriately selected according to the intended purpose, as long as it forms a solid electrolyte layer or an electrode mixture layer. Examples of targets include active material layers.

[0169] As described above, it is preferable that the maximum particle size of the solids contained in the liquid composition is smaller than the nozzle diameter of the inkjet head. It is also preferable that the ratio of the maximum particle size of the solids contained in the liquid composition to the nozzle diameter of the inkjet head is 0.8 or less.

[0170] <Other components and other steps>

[0171] Other components of the apparatus configured to prepare a solid electrolyte layer or electrode mixture layer are not particularly limited and may be appropriately selected according to the intended purpose, provided that the effects of this disclosure are not compromised. Examples of other components include heating units.

[0172] Other steps in the method for preparing a solid electrolyte layer or electrode mixture layer are not particularly limited and may be appropriately selected according to the intended purpose, provided that the effects of this disclosure are not compromised. Examples of other steps include a heating step.

[0173] -Heating Unit and Heating Procedure-

[0174] The heating unit is a unit configured to heat the liquid composition discharged from the discharge unit.

[0175] The heating step is the step of heating the liquid composition discharged in the discharge step.

[0176] This heating allows the liquid composition layer to be dried.

[0177] Figure 1 This is an example diagram of an exemplary device configured to prepare a solid electrolyte layer or electrode mixture layer to implement a method for preparing a solid electrolyte layer or electrode mixture layer according to this embodiment.

[0178] Figure 1 The apparatus shown, configured to prepare a solid electrolyte layer or electrode mixture layer, is an apparatus configured to prepare a solid electrolyte layer or electrode mixture layer using the aforementioned liquid composition. The solid electrolyte layer or electrode mixture layer apparatus includes: a discharge step unit 10, including a step of applying the liquid composition to a printing substrate 4 having a discharge target to form a liquid composition layer; and a heating step unit 30, including a heating step of heating the liquid composition layer to obtain a solid electrolyte layer or electrode mixture layer. The solid electrolyte layer or electrode mixture layer apparatus includes a conveying unit 5, which is configured to convey the printing substrate 4. The conveying unit 5 conveys the printing substrate 4 to the discharge step unit 10 at a previously set speed and then to the heating step unit 30.

[0179] There are no particular limitations on the method used to prepare the printing substrate 4 having the discharge target such as the active material layer, and known methods can be appropriately selected.

[0180] The discharge step unit 10 includes: a printer 1a, which is selected as desired to suit an inkjet printing method, i.e. an application method for performing the application step of applying a liquid composition to a printing substrate 4; a storage container 1b for storing the liquid composition; and a supply tube 1c through which the liquid composition stored in the storage container 1b is supplied to the printer 1a.

[0181] Storage container 1b stores liquid composition 7. Discharge step unit 110 discharges liquid composition 7 from printer 1a and applies liquid composition 7 to printing substrate 4 to form a liquid composition layer in the shape of a thin film. Storage container 1b can be integrated with a solid electrolyte layer or electrode mixture layer device, or it can be detachable from the solid electrolyte layer or electrode mixture layer device. Furthermore, storage container 1b can be a container for adding liquid composition to a storage container integrated with a solid electrolyte layer or electrode mixture layer device, or to a storage container detachable from a solid electrolyte layer or electrode mixture layer device.

[0182] Storage container 1b and supply pipe 1c can be selected as desired, provided that the liquid composition 7 can be stored and supplied stably.

[0183] like Figure 1 As shown, the heating step unit 30 includes a heater 3a and a solvent removal step, which removes the solvent retained in the liquid composition layer by heating and drying with the heater 3a. This allows the formation of a solid electrolyte layer or an electrode mixture layer. The solvent removal step can be performed in the heating step unit 30 under reduced pressure.

[0184] There are no particular limitations on heater 3a, and it can be appropriately selected according to the intended purpose. Examples of heater 3a include substrate heaters, IR heaters, and hot air heaters, or combinations thereof.

[0185] The heating temperature or time can be appropriately selected based on the boiling point of the solvent contained in the liquid composition 7 or the film thickness of the formed film.

[0186] Figure 2 Another example diagram illustrates an apparatus (liquid discharge apparatus) configured to prepare a solid electrolyte layer or electrode mixture layer to implement a method for preparing a solid electrolyte layer or electrode mixture layer according to this embodiment.

[0187] The liquid discharge device 300' can circulate the liquid composition through the liquid discharge head 306, tank 307 and pipe 308 by adjusting the pump 310 and valves 311 and 312.

[0188] The liquid discharge device 300' includes an external tank 313 and can supply the liquid composition from the external tank 313 to the tank 307 by regulating pump 310 and valves 311, 312 and 314 when the liquid composition in the tank 307 decreases.

[0189] Using equipment configured to prepare a solid electrolyte layer or electrode mixture layer, a liquid composition can be discharged to a desired location on the discharge target.

[0190] A solid electrolyte layer or electrode mixture layer may be suitably used as part of the configuration of, for example, an energy storage element. There are no particular limitations on components other than the solid electrolyte layer or electrode mixture layer of the energy storage element, and well-known components may be suitably selected. Examples of other components include positive electrodes, negative electrodes, and separators.

[0191] As a method for preparing energy storage elements, known methods may be appropriately selected, provided that the solid electrolyte layer or electrode mixture layer in the method is one of those disclosed herein.

[0192] There are no particular restrictions on the shape of energy storage elements, and they can be appropriately selected according to the intended purpose. The shape of energy storage elements can be... Figure 3 The shapes shown can also be appropriately selected from a variety of commonly used shapes depending on the application of the energy storage element. There are no particular limitations on the shape, and it can be appropriately selected according to the intended purpose. Examples of shapes include cylindrical shapes in which the sheet electrodes and solid electrolyte layers are spirally arranged; cylindrical shapes with an inside-out structure in which pellet electrodes and solid electrolyte layers are combined; and button shapes in which pellet electrodes and solid electrolyte layers are laminated.

[0193] Figure 3 An example diagram of an energy storage element is shown, which includes a solid electrolyte layer according to this embodiment.

[0194] like Figure 3 As shown, the energy storage element 110 according to this embodiment includes a positive electrode 11, a negative electrode 12 opposite to the positive electrode 11, and a solid electrolyte layer 13 disposed between the positive electrode 11 and the negative electrode 12.

[0195] The energy storage element 110 includes a container 15 that serves as the exterior for housing the positive electrode 11, the negative electrode 12, and the electrolyte layer 13 by encapsulating the positive electrode 11, the negative electrode 12, and the electrolyte layer 13; a positive electrode line 16 that penetrates the container 15 to connect to the positive electrode 11; and a negative electrode line 17 that also penetrates the container 15 to connect to the negative electrode 12.

[0196] <Applications>

[0197] There are no particular limitations on the applications of energy storage components, and they have a wide range of uses. Examples of applications for energy storage components include: power supplies for devices such as laptops, stylus computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, stereo headphones, handheld video recorders / players, LCD TVs, handheld cleaners, portable CD players, mini-disc players, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, motors, lighting equipment, toys, game consoles, clocks, stroboscopes, and cameras; and backup power supplies.

[0198] Example

[0199] The present disclosure will be described in more detail below through embodiments. This disclosure should not be construed as being limited to these embodiments.

[0200] Unless otherwise specified, in order to suppress the reaction between the inorganic solid electrolyte and moisture in the air, the following operations shall be carried out in an argon glove box maintained at a dew point below -70°C.

[0201] In the following preparation examples A1 to A4, examples A1 and A2, and comparative examples A1 to A3, ionic conductivity, particle size, and particle size distribution were measured in the following manner.

[0202] [Measurement of Ionic Conductivity]

[0203] First, the powder (30 mg) was placed in a 2.5 mm diameter press jig and molded into a pellet-shaped sample under a pressure of 10 MPa applied by a uniaxial hydraulic press. Gold powder was then added to the upper and lower surfaces of the pellet-shaped sample, and the resulting product was pressurized at 1 MPa to form an electrode.

[0204] The ionic conductivity (S / cm) was calculated in a 30℃ constant temperature chamber using the AC impedance method.

[0205] Evaluate whether the ionic conductivity is good or bad according to the following evaluation criteria.

[0206] A: Good ionic conductivity (ionic conductivity is 1×10⁻⁶). -4 (S / cm or higher).

[0207] B: Poor ionic conductivity (ionic conductivity is 1×10⁻⁶) -4 (S / cm or less).

[0208] Methods for measuring particle size and particle size distribution

[0209] The diameter D of the solid contained in the liquid composition is obtained in accordance with ISO 13320 in the following manner. 10 D50 D 90 and D m And the maximum particle size.

[0210] First, the liquid composition was diluted to a solids concentration of 0.1 ppm to 10 ppm using the same solvent as that contained in the liquid composition to obtain a diluted liquid. The diluted liquid was poured into a quartz glass container and then sealed with a gasket. Next, the gasket-sealed quartz glass container was removed from the glove box, and the diameter D was calculated using a laser diffraction / scattering particle size distribution analyzer (LA-960, obtained from Horiba, Ltd.). 10 D 50 D 90 and D m And the maximum particle size. Here, the dilution concentration is adjusted in such a way that the intensity of the transmitted light from the laser diffraction / scattering particle size distribution analyzer is within an appropriate range, using the same solvent contained in the liquid composition.

[0211] (Preparation Examples A1 to A4: Synthesis of Inorganic Solid Electrolytes A1 to A4)

[0212] As inorganic solid electrolytes A1 to A4, sulfide solid electrolytes (Li6PS5Cl) with different particle sizes were prepared according to document 1 (Deiseroth H.-J., S.-T. Kong, H. Eckert, J. Vannahme, C. Reiner, T. Zaiss and M. Schlosser, Angew. Chem., International Edition 47, 2008, pp. 755-758).

[0213] The ionic conductivity of the inorganic solid electrolytes prepared in Examples A1 to A4 was measured in the manner described above. The diameter D of the inorganic solid electrolytes prepared in Examples A1 to A4 was obtained by scanning electron microscopy (SEM). 10 D 50 D 90 and D m The results are shown in Table 1.

[0214] Table 1

[0215]

[0216]

[0217] (Examples A1 and A2 and Comparative Examples A1 to A3: Preparation of Liquid Compositions and Dry Powders)

[0218] [Preparation of Liquid Compositions]

[0219] In Examples A1 and A2 and Comparative Examples A1 to A3 below, liquid compositions were prepared in the following manner.

[0220] An inorganic solid electrolyte and a dispersant (obtained from Lubrizol Corporation, S21000) are added to a solvent. The inorganic solid electrolyte is added to the solvent at a concentration of 20% by mass relative to the liquid composition. The dispersant is added at a mass ratio of 1% by mass relative to the inorganic solid electrolyte.

[0221] As a dehydrating solvent, a solvent with a water content of less than 100 ppm, as confirmed by a Karl Fischer moisture titrator, was used.

[0222] [Preparation of dry powder]

[0223] The obtained liquid composition was dropped into an evaporating dish and heated on a hot plate maintained at 120°C for 1 hour to obtain a dry powder.

[0224] The ionic conductivity, particle size, and particle size distribution of the liquid compositions of Examples A1 to A2 and Comparative Examples A1 to A3 were measured in the manner described above, and the viscosity and inkjet ejection properties of the liquid compositions were evaluated in the manner described below.

[0225] [Viscosity of the liquid composition]

[0226] The viscosity of a liquid composition at 100 rpm and 25°C was measured using a Type B viscometer (cone-plate viscometer) equipped with a CPA-40Z rotor.

[0227] [Inkjet Ejection]

[0228] The inkjet ejection properties of the liquid composition were evaluated using a droplet observation instrument EV1000 (obtained from Ricoh Co., Ltd.) in the following manner.

[0229] The liquid composition to be evaluated is ejected from one nozzle (40 μm diameter) of the EV1000 inkjet head. If the liquid composition can be ejected continuously for more than 60 seconds, it is determined to be ejectable. For liquid compositions that can be ejected continuously for more than 60 seconds, the ejection rate is not a problem, as long as the liquid composition continues to be ejected for at least 60 seconds after it begins to be ejected. That is, as long as the liquid composition can be ejected continuously for at least 60 seconds from the start of ejection, whether the ejection rate changes over the time interval from the start of ejection to 60 seconds after the start of ejection is irrelevant.

[0230] -evaluate-

[0231] A: The liquid composition is expellable (it can be continuously expelled for more than 60 seconds).

[0232] B: The liquid composition is not repellent (it cannot be continuously discharged for 60 seconds).

[0233] <Example A1: Liquid Composition A and its Dry Powder>

[0234] Solid electrolyte A4 and a dispersant were added to octane (relative permittivity of 2.1, obtained from Tokyo Chemical Industry Co., Ltd.), and the resulting product was treated with a high-speed rotary homogenizer (obtained from Kinematica AG, MT3100S2) at 30,000 rpm for 1 hour to prepare liquid composition A.

[0235] The diameter D of the solid contained in liquid composition A, measured by laser diffraction. 10 D 50 D 90 and D m The maximum particle sizes are 0.12 μm, 0.8 μm, 2.1 μm, 1.2 μm and 5.0 μm, respectively.

[0236] The viscosity of the resulting liquid composition A is 8 mPa·s.

[0237] The ionic conductivity of the dry powder obtained from liquid composition A is 1.0 × 10⁻⁶. -3 S / cm.

[0238] The inkjet ejection performance of the obtained liquid composition A was evaluated using an EV1000. It was confirmed that liquid composition A could be continuously ejected for 60 seconds.

[0239] <Example A2: Liquid Composition B and its Dry Powder>

[0240] Solid electrolyte A1 (10 wt%), solid electrolyte A2 (7 wt%), and solid electrolyte A3 (3 wt%), along with a dispersant, were added to octane (relative permittivity 2.1, obtained from Tokyo Chemical Industry Co., Ltd.), and the resulting product was treated with an ultrasonic homogenizer (obtained from NIHONSEIKI KAISHALTD., US-300E) at 500W for 10 minutes to prepare liquid composition B.

[0241] The diameter D of the solid contained in liquid composition B, measured by laser diffraction. 10 D 50 D 90 and D m The maximum particle sizes are 0.25 μm, 0.9 μm, 5.0 μm, 1.8 μm and 7.0 μm, respectively.

[0242] The viscosity of the resulting liquid composition B is 10 mPa·s.

[0243] The ionic conductivity of the dry powder obtained from liquid composition B is 7 × 10⁻⁶. -4 S / cm.

[0244] The inkjet ejection performance of the obtained liquid composition B was evaluated using an EV1000. It was confirmed that liquid composition B could be continuously ejected for 60 seconds.

[0245] Comparative Example A1: Liquid Composition C and its Dry Powder>

[0246] Solid electrolyte A2 and a dispersant were added to octane (relative permittivity of 2.1, obtained from Tokyo Chemical Industry Co., Ltd.), and the resulting product was treated with a high-speed rotary homogenizer (obtained from Kinematica AG, MT3100S2) at 30,000 rpm for 1 hour to prepare liquid composition C.

[0247] The diameter D of the solid contained in liquid composition C, measured by laser diffraction. 10 D 50 D 90 and D m The maximum particle sizes are 0.6 μm, 0.8 μm, 3.0 μm, 1.5 μm and 4.5 μm, respectively.

[0248] The viscosity of the resulting liquid composition C is 10 mPa·s.

[0249] The ionic conductivity of the dry powder obtained from liquid composition C is 5 × 10⁻⁶. -5 S / cm.

[0250] The inkjet ejection performance of the obtained liquid composition C was evaluated using an EV1000. It was confirmed that liquid composition C could be continuously ejected for 60 seconds.

[0251] <Comparative Example A2: Liquid Composition D and its Dry Powder>

[0252] Solid electrolytes A1 (10 wt%) and A3 (10 wt%), along with a dispersant, were added to octane (relative permittivity 2.1, obtained from Tokyo Chemical Industry Co., Ltd.), and the resulting product was treated with a wet jet mill (obtained from SUGINO MACHINE LIMITED, STAR BURST MINIMO) at 180 MPa to prepare liquid composition D.

[0253] The diameter D of the solid contained in the liquid composition D, measured by laser diffraction. 10 D 50 D 90and D m The maximum particle sizes are 0.2 μm, 1.1 μm, 6.5 μm, 1.9 μm and 16.0 μm, respectively.

[0254] The viscosity of the resulting liquid composition D is 8 mPa·s.

[0255] The ionic conductivity of the dry powder obtained from liquid composition D is 7 × 10⁻⁶. -4 S / cm.

[0256] The inkjet ejection performance of the obtained liquid composition D was evaluated using an EV1000. Liquid composition D could not be ejected continuously for 60 seconds, and clogging occurred during ejection. Therefore, the performance of liquid composition D is unacceptable.

[0257] <Comparative Example A3: Liquid Composition E and its Dry Powder>

[0258] Solid electrolyte A1 (15% by mass) and solid electrolyte A4 (5% by mass) and a dispersant were added to octane (relative permittivity of 2.1, obtained from Tokyo Chemical Industry Co., Ltd.), and the resulting product was treated with an ultrasonic homogenizer (obtained from NIHONSEIKI KAISHALTD., US-300E) at 500W for 10 minutes to prepare liquid composition E.

[0259] The diameter D of the solid contained in liquid composition E, measured by laser diffraction. 10 D 50 D 90 and D m The maximum particle sizes are 0.4 μm, 0.8 μm, 7.0 μm, 3.0 μm and 19.0 μm, respectively.

[0260] The viscosity of the resulting liquid composition E is 11 mPa·s.

[0261] The ionic conductivity of the dry powder obtained from liquid composition E is 4 × 10⁻⁶. -4 S / cm.

[0262] The inkjet ejection performance of the obtained liquid composition E was evaluated using an EV1000. Liquid composition E could not be ejected continuously for 60 seconds, and clogging occurred during ejection. Therefore, the performance of liquid composition E is unacceptable.

[0263] The results of Examples A1 and A2 and Comparative Examples A1 to A3 are shown in Table 2 below.

[0264] Table 2

[0265]

[0266] (Preparation Example B1: Synthesis of Inorganic Solid Electrolyte B1)

[0267] As an inorganic solid electrolyte B1, a sulfide solid electrolyte (Li6PS5Cl) (LPSC) of silver sulfide type was synthesized according to document 2 (Rosero-Navarro Nataly Carolina, et al., Journal of Power Sources 396, 2018, pp.33-40).

[0268] (Preparation Example B2: Synthesis of Inorganic Solid Electrolyte B2)

[0269] Li was synthesized as an inorganic solid electrolyte B2 according to document 3 (Kwon Ohmin, Masaaki Hirayama, Kota Suzuki, Yuki Kato, Toshiya Saito, Masao Yonemura, Takashi Kamiyama and Ryoji Kanno, J. Mater. Chem. A, 3, 2015, pp. 438-446). 10 GeP2S 12 (LGPS).

[0270] (Examples B1 to B11 and Reference Examples B1 to B8: Preparation of Liquid Compositions)

[0271] In Examples B1 to B11 and Reference Examples B1 to B8 below, an inorganic solid electrolyte and a dispersant were added to a dehydrated solvent, and the resulting product was mixed for 10 minutes at 70% power output using an ultrasonic homogenizer (US-300E) obtained from NIHONSEIKI KAISHALTD. to obtain a liquid composition.

[0272] As a dehydrating solvent, a solvent with a water content of less than 100 ppm, as confirmed by a Karl Fischer moisture titrator, was used.

[0273] [evaluate]

[0274] The vapor pressure of the solvent used in Examples B1 to B11 and Reference Examples B1 to B8 at 25°C was obtained in the following manner.

[0275] For the liquid compositions of Examples B1 to B11 and Reference Examples B1 to B8 below, the detection of hydrogen sulfide, inkjet ejection performance, and re-ejection performance after shutdown were evaluated in the following manner.

[0276] [Vapor pressure at 25°C]

[0277] For the vapor pressure of the solvent, consult the Safety Data Sheet (SDS) if the relevant vapor pressure is written into the SDS. For solvents whose vapor pressure is not written into their SDS, the vapor pressure can be measured using the liquid vapor pressure gauge method described in document 4 (Environment Agency, Environmental Health Department, Office of Health Studies, Studies into Physicochemical Characterization of Chemical Substances, Japan Environment Association, 1986).

[0278] [Detection of hydrogen sulfide]

[0279] Determine whether the mixed liquid composition releases hydrogen sulfide in the following manner.

[0280] Pour the liquid composition (10 mL) into a spiral tube and store it in an argon glove box at 25°C for 1 hour. After storage, bring the hydrogen sulfide sensor (obtained from Honeywell Japan Ltd., BW SOLO LITE) close to the spiral tube and open the spiral tube. Here, hydrogen sulfide is determined to have been released when the hydrogen sulfide sensor maintains a value greater than or equal to 0.1 ppm for more than 3 seconds.

[0281] For safety reasons, any liquid composition rated "b" in this test was not evaluated for inkjet ejection and post-stop re-ejection properties.

[0282] -evaluate-

[0283] a: There is no hydrogen sulfide release.

[0284] b: Hydrogen sulfide is being released.

[0285] [Inkjet Ejection]

[0286] The inkjet ejection properties of the liquid composition were evaluated using a droplet observation instrument EV1000 (obtained from Ricoh Co., Ltd.) in the following manner.

[0287] The liquid composition to be evaluated is ejected from one nozzle (40 μm diameter) of the inkjet head of the EV1000. If the liquid composition can be ejected continuously for more than 60 seconds, the liquid composition is determined to be ejectable. For liquid compositions that can be ejected continuously for more than 60 seconds, the ejection rate of the liquid composition is not a problem, as long as the liquid composition continues to be ejected for at least 60 seconds after it begins to be ejected. That is, as long as the liquid composition can be ejected continuously for at least 60 seconds from the start of ejection, it is irrelevant whether the ejection rate of the liquid composition changes over the time period from the start of ejection to 60 seconds after the start of ejection.

[0288] -evaluate-

[0289] A: The liquid composition is expellable (it can be continuously expelled for more than 60 seconds).

[0290] B: The liquid composition is not repellent (it cannot be continuously discharged for 60 seconds).

[0291] [Re-emission after cessation]

[0292] Using a droplet observation instrument EV1000 (obtained from Ricoh Co., Ltd.), the re-ejection property of a liquid composition after it has been ejected by inkjet printing was evaluated in the following manner.

[0293] The liquid composition to be evaluated was ejected from one nozzle (40 μm in diameter) of the inkjet head of the EV1000, held for 60 seconds, left to stand for 5 minutes, and then ejected again. If the liquid composition was successfully ejected during this second ejection, the liquid composition was determined to have post-ejection re-ejection property.

[0294] -evaluate-

[0295] A: The liquid composition has re-discharge properties.

[0296] B: The liquid composition is not re-dischargeable.

[0297] <Example B1>

[0298] 40 g of undecane (obtained from Tokyo Chemical Industry Co., Ltd.) was weighed out as a solvent, and inorganic solid electrolyte B1 (56 g) and dispersant (SOLSPERSE3000 (hereinafter referred to as "S-3000")) (4 g) were added to it. The resulting products were mixed using an ultrasonic homogenizer to obtain the liquid composition of Example B1.

[0299] <Example B2>

[0300] The liquid composition of Example B2 was prepared in the same manner as in Example B1, except that tetradecane (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent.

[0301] <Example B3>

[0302] The liquid composition of Example B3 was prepared in the same manner as in Example B1, except that 2-butyloctane (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent.

[0303] <Example B4>

[0304] The liquid composition of Example B4 was prepared in the same manner as in Example B1, except that butylphenyl ether (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent.

[0305] <Example B5>

[0306] The liquid composition was prepared in the same manner as in Example B1—except that dihexyl ether (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent to obtain the liquid composition of Example B5.

[0307] <Example B6>

[0308] The liquid composition of Example B6 was prepared in the same manner as in Example B1, except that 2-nonyl acetate (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent.

[0309] <Example B7>

[0310] The liquid composition of Example B7 was prepared in the same manner as in Example B1, except that 2-ethylhexyl acetate (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent.

[0311] <Example B8>

[0312] The liquid composition of Example B8 was prepared in the same manner as in Example B1, except that 2-ethylhexyl propionate (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent.

[0313] <Example B9>

[0314] The liquid composition of Example B9 was prepared in the same manner as in Example B1, except that MALIALIM SC-0708A (obtained from NOF Corporation, hereinafter referred to as "SC0708A") was used instead of S-3000 as a dispersant.

[0315] <Example B10>

[0316] The liquid composition of Example B10 was prepared in the same manner as in Example B1, except that inorganic solid electrolyte B2 was used instead of inorganic solid electrolyte B1 as the inorganic solid electrolyte.

[0317] <Example B11>

[0318] The liquid composition was prepared in the same manner as in Example B1—except that a mixture of tetradecane and 2-ethylhexyl acetate in a mass ratio of 1:1 was used instead of undecane as the solvent to obtain the liquid composition of Example B11.

[0319] <Reference Example B1>

[0320] The liquid composition was prepared in the same manner as in Example B1—except that n-decane (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent to obtain the liquid composition of Reference Example B1.

[0321] <Reference Example B2>

[0322] The liquid composition was prepared in the same manner as in Example B1—except that n-pentadecane (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent to obtain the liquid composition of Reference Example B2.

[0323] <Reference Example B3>

[0324] The liquid composition was prepared in the same manner as in Example B1—except that propoxybenzene (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent to obtain the liquid composition of Reference Example B3.

[0325] <Reference Example B4>

[0326] The liquid composition was prepared in the same manner as in Example B1—except that diheptane (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent to obtain the liquid composition of Reference Example B4.

[0327] <Reference Example B5>

[0328] The liquid composition was prepared in the same manner as in Example B1—except that 1,4-diethoxybenzene (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent to obtain the liquid composition of Reference Example B5.

[0329] <Reference Example B6>

[0330] The liquid composition was prepared in the same manner as in Example B1—except that n-octyl acetate (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent to obtain the liquid composition of Reference Example B6.

[0331] <Reference Example B7>

[0332] The liquid composition was prepared in the same manner as in Example B1, except that 2-ethylhexyl butyrate (obtained from Tokyo Chemical Industry Co., Ltd.) was used instead of undecane as the solvent to obtain the liquid composition of Reference Example B7.

[0333] <Reference Example B8>

[0334] Prepare the liquid composition in the same manner as in Example B1—except without using a dispersant—to obtain the liquid composition of Reference Example B8.

[0335] The evaluation results and other details of the above-described Examples B1 to B11 and Reference Examples B1 to B8 are shown in Tables 3-1 and 3-2 below. In the item "Whether hydrogen sulfide is released" in Tables 3-1 and 3-2, "a" indicates "no hydrogen sulfide is released" and "b" indicates "hydrogen sulfide is released".

[0336] Table 3-1

[0337]

[0338]

[0339] Table 3-2

[0340]

[0341] The results of Examples B1, B2, and B3, and Reference Examples B1 and B2, using solvents with aliphatic hydrocarbon structures, reveal the following: When undecane (Example B1) and tetradecane (Example B2), with vapor pressures of 0.1 hPa or higher and 1.0 hPa or lower, were used, hydrogen sulfide was not detected, inkjet ejection performance was good, and re-ejection performance after stopping was also good. In contrast, when n-decane (Reference Example B1), with a vapor pressure higher than 1.0 hPa, was used, the inkjet ejection port became clogged upon re-ejection after stopping due to accelerated drying at the ejection port. When n-pentadecane (Reference Example B2), with a vapor pressure lower than 0.1 hPa and high viscosity, was used, the liquid composition with added n-pentadecane also exhibited high viscosity and caused clogging in the inkjet ejection performance evaluation. Based on these results, solvents with aliphatic hydrocarbon structures are preferred, having vapor pressures of 0.1 hPa or higher and 1.0 hPa or lower. When 2-butyloctane (Example B3) was used, the results for all evaluation items were good, and it can be seen that the same effect can be obtained when branched aliphatic hydrocarbons are used.

[0342] The results of Examples B4 and B5 and Reference Examples B3, B4 and B5 using solvents with ether structures reveal the following: When butylphenyl ether (Example B4) and dihexyl ether (Example B5) with vapor pressures of 0.1 hPa or higher and 1.0 hPa or lower are used, hydrogen sulfide is not detected, inkjet ejection performance is good, and re-ejection performance after stopping is also good. In contrast, when propoxybenzene (Reference Example B3) with a vapor pressure higher than 1.0 hPa is used, the inkjet ejection port is blocked upon re-ejection after stopping due to accelerated drying at the inkjet ejection port. When diheptyl ether (Reference Example B4) with a vapor pressure lower than 0.1 hPa and high viscosity is used, the liquid composition with added diheptyl ether also has high viscosity and causes clogging in the inkjet ejection performance evaluation. Based on these results, solvents with ether structures are preferred, also solvents with vapor pressures of 0.1 hPa or higher and 1.0 hPa or lower. When 1,4-diethoxybenzene (Reference Example B5) with a diether structure is used, hydrogen sulfide is detected in the liquid composition. Therefore, structures with multiple ether groups are unsuitable for use because such structures are highly reactive with sulfide solid electrolytes.

[0343] Examples B6, B7, and B8, and Reference Examples B6 and B7, using solvents with ester structures, reveal the following: When using 2-nonyl acetate (Example B6) and 2-ethylhexyl acetate (Example B7), which have a vapor pressure of 0.1 hPa or higher and 1.0 hPa or lower and are branched at the first and second carbon positions relative to the oxygen side of the ester group, respectively, no hydrogen sulfide was detected, inkjet ejection was good, and re-ejection after stopping was also good. In contrast, when using n-octyl acetate (Reference Example B6), which has no branching at the carbon position relative to the oxygen side of the ester group, hydrogen sulfide was detected in the liquid composition. Based on these results, it was found that esters with no branching at the carbon position relative to the oxygen side are unsuitable for use because such esters are highly reactive with sulfide solid electrolytes. When 2-ethylhexyl butyrate (Reference Example B7), in which the propyl group is bonded to the carbon side of the ester group, is used, hydrogen sulfide release is suppressed, but clogging occurs during inkjet ejection because the solvent vapor pressure is below 0.1 hPa, resulting in a high viscosity of the liquid composition. In contrast, when 2-ethylhexyl propionate (Example B8), in which the ethyl group is bonded to the carbon side of the ester group, is used, no clogging occurs during inkjet ejection because the solvent vapor pressure falls within the range of 0.1 hPa to 1.0 hPa. Based on these results, it is found that the preferred solvent having an ester structure is one with a vapor pressure of 0.1 hPa to 1.0 hPa and having a methyl or ethyl group as the group bonded to the carbon side of the ester group.

[0344] Examples B9 and Reference Example B8 reveal the following. In Reference Example B8, where no dispersant is added, clogging occurs during inkjet ejection due to particle flocculation. In Example B9, where the type of dispersant is changed relative to Example B1, good ejection performance is exhibited as in Example B1. Based on these results, it is evident that the addition of a dispersant is essential, while on the other hand, the effects of this disclosure can be obtained with any type of dispersant that has a dispersing effect, regardless of the type of dispersant.

[0345] In Example B10, where the type of inorganic solid electrolyte is changed relative to Example B1, good discharge performance is exhibited as in Example B1. Based on this result, it is evident that the effects of this disclosure can be obtained regardless of the type of solid electrolyte.

[0346] In Example B11, where a mixed solvent is used as the solvent, good discharge performance is exhibited as in Example B1. Based on this result, it is evident that the effects of this disclosure can also be obtained when a mixed solvent is used as the solvent.

[0347] The aspects disclosed herein are, for example, as follows.

[0348] <1> Liquid composition, comprising:

[0349] Solvent;

[0350] Inorganic solid electrolytes; and

[0351] Dispersant, in which

[0352] The dispersant is soluble in the solvent, and

[0353] The particle size (D) of the 10% volume fraction of solid component contained in the liquid composition. 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It was measured using laser diffraction.

[0354] D 90 / D 10 >10---Equation (1)

[0355] D 50 <1μm---Equation (2)

[0356] D m <2μm---Equation (3).

[0357] <2> Liquid composition, comprising:

[0358] Solvent;

[0359] Inorganic solid electrolytes; and

[0360] Dispersant, in which

[0361] The solvent is at least one selected from (I) aliphatic hydrocarbons, (II) monoethers and (III) branched esters, wherein the (I) aliphatic hydrocarbons, the (II) monoethers and the (III) branched esters have a vapor pressure of more than 0.1 hPa and less than 1.0 hPa at 25°C.

[0362] <3> according to <1> Liquid compositions,

[0363] The solvent is selected from at least one of (I) aliphatic hydrocarbons, (II) monoethers and (III) branched esters, wherein the (I) aliphatic hydrocarbons, the (II) monoethers and the (III) branched esters have a vapor pressure of more than 0.1 hPa and less than 1.0 hPa at 25°C.

[0364] <4> According to any one of <1> to <3>, the liquid composition

[0365] The viscosity of the liquid composition is below 200 mPa·s.

[0366] <5> Liquid compositions according to any one of <1> to <4>

[0367] The liquid composition contains solids with a maximum particle size of less than 32 μm.

[0368] <6> Liquid composition, comprising:

[0369] Solvent;

[0370] Inorganic solid electrolytes; and

[0371] Dispersant, in which

[0372] The dispersant is soluble in the solvent.

[0373] The particle size (D) of the 10% volume fraction of solid component contained in the liquid composition. 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It was measured using laser diffraction.

[0374] D 90 / D 10 >10---Equation (1)

[0375] D 50 <1μm---Equation (2)

[0376] D m <2μm---Equation (3), and

[0377] The liquid composition is ejected using an inkjet head.

[0378] <7> Liquid composition, comprising:

[0379] Solvent;

[0380] Inorganic solid electrolytes; and

[0381] Dispersant, in which

[0382] The solvent is at least one selected from (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters, wherein the (I) aliphatic hydrocarbon, the (II) monoether, and the (III) branched ester have a vapor pressure of 0.1 hPa or higher and 1.0 hPa or lower at 25°C.

[0383] The liquid composition is ejected using an inkjet head.

[0384] <8> According to the liquid composition of <6>,

[0385] The solvent is selected from at least one of (I) aliphatic hydrocarbons, (II) monoethers and (III) branched esters, wherein the (I) aliphatic hydrocarbons, the (II) monoethers and the (III) branched esters have a vapor pressure of more than 0.1 hPa and less than 1.0 hPa at 25°C.

[0386] <9> According to any one of <6> to <8>, the liquid composition

[0387] The viscosity of the liquid composition is the viscosity at which the liquid composition can be discharged from the nozzle of the inkjet head.

[0388] <10> Liquid composition according to any one of <6> to <9>

[0389] The maximum particle size of the solids contained in the liquid composition is smaller than the nozzle diameter of the inkjet head.

[0390] <11> Liquid compositions according to any one of <6> to <10>

[0391] The ratio of the maximum particle size of the solid contained in the liquid composition to the nozzle diameter of the inkjet head is less than 0.8.

[0392] <12> According to any one of <1> to <11>, the liquid composition

[0393] The solvent has a relative permittivity of 6.0 or less at 25°C.

[0394] <13> according to <1> to <12> Liquid composition of any one of the following,

[0395] The inorganic solid electrolyte in the liquid composition has a solid concentration of 15% by mass or more.

[0396] <14> Liquid compositions according to any one of <2> to <5> and <7> to <13>

[0397] The (I) aliphatic hydrocarbons mentioned therein are aliphatic hydrocarbons containing 11 to 14 carbon atoms.

[0398] <15> Liquid compositions according to any one of <2> to <5> and <7> to <13>

[0399] The (II) monoethers therein are monoethers having a basic skeleton consisting of 11 to 13 molecules.

[0400] <16> Liquid compositions according to any one of <2> to <5> and <7> to <13>

[0401] The (III) branched ester is any one of the following:

[0402] (i) an ester in which a hydrocarbon group containing two or fewer carbon atoms is bonded to the carbon side of an ester group and a branched hydrocarbon group is bonded to the oxygen side of the ester group; and

[0403] (ii) An ester in which a hydrocarbon group containing three or fewer carbon atoms is bonded to the oxygen side of an ester group and a branched hydrocarbon group is bonded to the carbon side of the ester group.

[0404] <17> Liquid compositions according to any one of <2> to <5> and <7> to <16>

[0405] The solvent used is one solvent or a mixture of two or more solvents having a structure selected from the (I) aliphatic hydrocarbon, the (II) monoether and the (III) branched ester.

[0406] <18> A method for preparing a liquid composition according to any one of <1> to <17>, said method comprising:

[0407] The inorganic solid electrolyte and the dispersant are dissolved or dispersed in the solvent.

[0408] <19> The method for preparing a liquid composition according to <18> further includes...

[0409] The particle size of the solids contained in the liquid composition is adjusted by mechanical means.

[0410] <20> According to the method for preparing liquid compositions in <19>,

[0411] The mechanical method is carried out by a device selected from a high-speed rotary homogenizer, a wet jet mill, a wet bead mill, or a combination of two or more of these.

[0412] <21> Storage container, including:

[0413] according to <1> to <17> A liquid composition of any one of the following, wherein

[0414] The liquid composition is stored in the storage container.

[0415] <22> An apparatus configured to prepare a solid electrolyte layer or an electrode mixture layer, the apparatus comprising:

[0416] according to <21> Storage containers; and

[0417] A discharge unit configured to discharge a liquid composition stored in the storage container using an inkjet head.

[0418] <23> A method for preparing a solid electrolyte layer or an electrode mixture layer, the method comprising:

[0419] Dispensing a liquid composition according to any one of <1> to <17> using an inkjet head.

[0420] <24> According to the method for preparing a solid electrolyte layer or electrode mixture layer as described in <23>,

[0421] The maximum particle size of the solids contained in the liquid composition is smaller than the nozzle diameter of the inkjet head.

[0422] <25> According to the method for preparing a solid electrolyte layer or electrode mixture layer as described in <23> or <24>,

[0423] The ratio of the maximum particle size of the solid contained in the liquid composition to the nozzle diameter of the inkjet head is less than 0.8.

[0424] The liquid composition according to any one of <1> to <17>, the method for preparing the liquid composition according to any one of <18> to <20>, the storage container according to <21>, the apparatus configured to prepare a solid electrolyte layer or electrode mixture layer according to <22>, or the method for preparing a solid electrolyte layer or electrode mixture layer according to any one of <23> to <25> can solve various problems in the prior art and achieve the purpose of this disclosure.

[0425] Furthermore, this disclosure is not limited to these embodiments, and various changes and modifications can be made without departing from the scope of the invention.

Claims

1. A liquid composition comprising: Solvent; Inorganic solid electrolytes; and Dispersant, in which The dispersant is soluble in the solvent, and The particle size (D) of the 10% volume fraction of solid component contained in the liquid composition. 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It was measured using laser diffraction. D 90 / D 10 >10---Equation (1) D 50 <1μm---Equation (2) D m <2μm---Equation (3), The solvent has a relative permittivity of 6.0 or less at 25°C.

2. The liquid composition according to claim 1, The solvent is selected from at least one of (I) aliphatic hydrocarbons, (II) monoethers and (III) branched esters, wherein the (I) aliphatic hydrocarbons, the (II) monoethers and the (III) branched esters have a vapor pressure of more than 0.1 hPa and less than 1.0 hPa at 25°C.

3. The liquid composition according to claim 1, The viscosity of the liquid composition is below 200 mPa·s.

4. The liquid composition according to claim 1, The liquid composition contains a solid with a maximum particle size of less than 32 μm.

5. The liquid composition according to claim 1, The inorganic solid electrolyte in the liquid composition has a solid concentration of 15% by mass or more.

6. The liquid composition according to claim 2, The (I) aliphatic hydrocarbons mentioned therein are aliphatic hydrocarbons containing 11 to 14 carbon atoms.

7. The liquid composition according to claim 2, The (II) monoethers therein are monoethers having a basic skeleton consisting of 11 to 13 molecules.

8. The liquid composition according to claim 2, The (III) branched ester is any one of the following: (i) an ester in which a hydrocarbon group containing two or fewer carbon atoms is bonded to the carbon side of an ester group and a branched hydrocarbon group is bonded to the oxygen side of the ester group; and (ii) An ester in which a hydrocarbon group containing three or fewer carbon atoms is bonded to the oxygen side of an ester group and a branched hydrocarbon group is bonded to the carbon side of the ester group.

9. The liquid composition according to any one of claims 2 to 8, The solvent used is one solvent or a mixture of two or more solvents having a structure selected from the (I) aliphatic hydrocarbon, the (II) monoether and the (III) branched ester.

10. A liquid composition comprising: Solvent; Inorganic solid electrolytes; and Dispersant, in which The dispersant is soluble in the solvent, and The particle size (D) of the 10% volume fraction of solid component contained in the liquid composition. 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It was measured using laser diffraction. D 90 / D 10 >10---Equation (1) D 50 <1μm---Equation (2) D m <2μm---Equation (3), The solvent is at least one selected from (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters, wherein the (I) aliphatic hydrocarbon, the (II) monoether, and the (III) branched ester have a vapor pressure of 0.1 hPa or higher and 1.0 hPa or lower at 25°C. The (I) aliphatic hydrocarbons mentioned therein are aliphatic hydrocarbons containing 11 to 14 carbon atoms.

11. A liquid composition comprising: Solvent; Inorganic solid electrolytes; and Dispersant, in which The dispersant is soluble in the solvent, and The particle size (D) of the 10% volume fraction of solid component contained in the liquid composition. 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It was measured using laser diffraction. D 90 / D 10 >10---Equation (1) D 50 <1μm---Equation (2) D m <2μm---Equation (3), The solvent is at least one selected from (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters, wherein the (I) aliphatic hydrocarbon, the (II) monoether, and the (III) branched ester have a vapor pressure of 0.1 hPa or higher and 1.0 hPa or lower at 25°C. The (II) monoethers therein are monoethers having a basic skeleton consisting of 11 to 13 molecules.

12. A liquid composition comprising: Solvent; Inorganic solid electrolytes; and Dispersant, in which The dispersant is soluble in the solvent, and The particle size (D) of the 10% volume fraction of solid component contained in the liquid composition. 10 ), particle size of 50% volume fraction component (D) 50 ), particle size of 90% volume fraction component (D) 90 ) and the mode path (D m ) satisfies the following equations (1) to (3), where D 10 D 50 D 90 and D m It was measured using laser diffraction. D 90 / D 10 >10---Equation (1) D 50 <1μm---Equation (2) D m <2μm---Equation (3), The solvent is at least one selected from (I) aliphatic hydrocarbons, (II) monoethers, and (III) branched esters, wherein the (I) aliphatic hydrocarbon, the (II) monoether, and the (III) branched ester have a vapor pressure of 0.1 hPa or higher and 1.0 hPa or lower at 25°C. The (III) branched ester is any one of the following: (i) an ester in which a hydrocarbon group containing two or fewer carbon atoms is bonded to the carbon side of an ester group and a branched hydrocarbon group is bonded to the oxygen side of the ester group; and (ii) An ester in which a hydrocarbon group containing three or fewer carbon atoms is bonded to the oxygen side of an ester group and a branched hydrocarbon group is bonded to the carbon side of the ester group.

13. A method for preparing a solid electrolyte layer or an electrode mixture layer, the method comprising: The liquid composition according to any one of claims 1 to 12 is dispensed using an inkjet head.

14. The method for preparing a solid electrolyte layer or electrode mixture layer according to claim 13, The maximum particle size of the solid contained in the liquid composition is smaller than the nozzle diameter of the inkjet head.

15. The method for preparing a solid electrolyte layer or electrode mixture layer according to claim 13 or 14, The ratio of the maximum particle size of the solid contained in the liquid composition to the nozzle diameter of the inkjet head is less than 0.8.

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