Battery

Abstract

To provide a battery in which battery resistance is suppressed.SOLUTION: According to the present disclosure, there is provided a battery including a positive electrode active material layer, a negative electrode active material layer, and an electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, and at least one of the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer contains a Li-Al halide-based molten salt. Therein: the Li-Al halide-based molten salt contains a first salt as a main component and a second salt as an additive component; the first salt is a Li-Al halide salt containing at least LiAlCl4; and the second salt is an ionic liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to batteries. [Background technology]

[0002] In recent years, the development of batteries has been actively pursued. For example, in the automotive industry, development of batteries for use in electric vehicles (BEVs), plug-in hybrid vehicles (PHEVs), and hybrid electric vehicles (HEVs) is underway. Furthermore, development of components and materials for use in these batteries is also underway.

[0003] For example, Patent Document 1 discloses a battery including a first polymer electrolyte layer containing an aliphatic dinitrile compound, a lithium salt, and a lithium ion conductive polymer; and a second polymer electrolyte layer containing an ionic liquid, a lithium salt, and a lithium ion conductive polymer. Patent Document 2 discloses that the negative electrode active material layer in an all-solid-state battery contains a molten salt. Patent Document 3 discloses a liquid electrolyte composition for a lithium metal secondary battery, and discloses that the liquid electrolyte composition may contain LiAlCl4. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2019-521475 [Patent Document 2] Japanese Patent Publication No. 2023-074634 [Patent Document 3] Japanese Patent Application Publication No. 2019-114531 Summary of the Invention [Problem to be solved by the invention]

[0005] To improve battery performance, it is desirable to improve ionic conductivity and suppress battery resistance. The use of LiAl halide salts, such as LiAlCl4, as electrolytes in batteries is also being considered. However, because LiAl halide salts tend to have low ionic conductivity, batteries using LiAl halide salts as electrolytes tend to have high battery resistance.

[0006] The present disclosure has been made in view of the above circumstances, and has as its main object to provide a battery with reduced battery resistance. [Means for solving the problem]

[0007] [1] A battery having a positive electrode active material layer, a negative electrode active material layer, and an electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, at least one of the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer contains a LiAl halide-based molten salt; The LiAl halide-based molten salt contains a first salt as a main component and a second salt as an additive component, the first salt is a LiAl halide salt containing at least LiAlCl4, The battery, wherein the second salt is an ionic liquid.

[0008] [2] The battery according to [1], wherein the proportion of the second salt in the LiAl halide-based molten salt is 10 mol % or more and 30 mol % or less.

[0009] [3] the first salt comprises the LiAlCl4 and LiAlI4; The battery according to [1] or [2], wherein the proportion of the LiAlCl4 in the first salt is 20 mol % or more and 60 mol % or less.

[0010] [4] The battery according to any one of [1] to [3], wherein the second salt contains, as a cationic component, at least one of a sulfonium-based cation, a pyrrolidinium-based cation, a pyridinium-based cation, an ammonium-based cation, and a metal ion.

[0011] [5] The battery according to [4], wherein the cationic component is at least one of methyldiethylsulfonium, tetraethylsulfonium, N-methyl-N-methoxymethylpyrrolidinium, N-methyl-N-propylpyrrolidinium, and 1-propyl-3-methylpyridinium.

[0012] [6] The battery according to any one of [1] to [5], wherein the second salt contains, as an anion component, at least one of a sulfonylamide anion, a sulfate anion, and a halogen ion.

[0013] [7] The battery according to [6], wherein the anion component is at least one of bis(trifluoromethanesulfonyl)amide, bis(fluorosulfonyl)amide, and fluorosulfonyl(trifluoromethanesulfonylamide).

[0014] [8] The battery according to any one of [1] to [7], wherein the melting point of the LiAl halide molten salt is 10°C or higher and 70°C or lower.

[0015] [9] The ionic conductivity of the above LiAl halide molten salt at 25°C is 4.9 × 10 -5 The battery according to any one of [1] to [8], wherein the saturation voltage is 1.0 V / cm or more.

[0016]

[10] The ionic conductivity of the above LiAl halide molten salt at 25°C is 3.4 × 10 -3 The battery according to any one of [1] to [9], wherein the saturation voltage is 0.05 V / cm or less.

[0017]

[11] The battery according to any one of [1] to

[10] , wherein the negative electrode active material layer contains the LiAl halide-based molten salt.

[0018]

[12] The battery according to any one of [1] to

[11] , wherein the battery is a solid-state battery. [Effects of the Invention]

[0019] The present disclosure has an effect of providing a battery with reduced resistance. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a battery according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0021] The battery according to the present disclosure will be described in detail below.

[0022] FIG. 1 is a schematic cross-sectional view illustrating a battery according to the present disclosure. Note that FIG. 1 is a schematic illustration of the battery according to the present disclosure, and the size and shape of each component are appropriately exaggerated for ease of understanding. The battery 10 shown in FIG. 1 includes a positive electrode active material layer 1, a negative electrode active material layer 2, and an electrolyte layer 3 disposed between the positive electrode active material layer 1 and the negative electrode active material layer 2. In particular, in the battery 10 according to the present disclosure, at least one of the positive electrode active material layer 1, the negative electrode active material layer 2, and the electrolyte layer 3 contains a LiAl halide-based molten salt. The LiAl halide-based molten salt contains a first salt as a main component and a second salt as an additive component. The first salt is a LiAl halide salt containing at least LiAlCl4, and the second salt is an ionic liquid.

[0023] In the battery according to the present disclosure, at least one of the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer contains a predetermined LiAl halide-based molten salt, and therefore the battery resistance is suppressed.

[0024] The use of LiAl halide salts as electrolytes in batteries has been investigated. However, LiAl halide salts tend to have relatively low ionic conductivity. This is presumably due to the strong interaction between the Li cation and the Al halide anion, which inhibits the diffusion of Li.

[0025] In contrast, the LiAl halide-based molten salt contained in the battery of the present disclosure has a first salt, which is a LiAl halide salt containing at least LiAlCl4, as its main component, and a second salt, which is an ionic liquid, as an additive component, resulting in good ionic conductivity. This is presumably because LiAlCl4 exhibits relatively good ionic conductivity among LiAl halide salts, and because the second salt effectively suppresses the interaction between Li cations and Al halide anions. As a result, the resistance of the battery containing the LiAl halide-based molten salt is suppressed.

[0026] Furthermore, particularly when the battery of the present disclosure is a solid-state battery, the following advantages are also obtained. First, in solid-state batteries, electrode layers such as the negative electrode active material layer expand and contract during charge and discharge, which can cause cracks. When cracks occur, the ionic and electronic conduction paths are severed, and repeated charge and discharge can increase the battery resistance. In this regard, because the LiAl halide-based molten salt of the present disclosure has a relatively low melting point, even if cracks occur in the electrode layer, the fluid molten salt can effectively fill the cracks. As a result, a solid-state battery containing a LiAl halide-based molten salt suppresses an increase in battery resistance due to the disconnection of the ionic and electronic conduction paths, resulting in good cycle characteristics.

[0027] 1. LiAl halide molten salt The LiAl halide molten salt according to the present disclosure contains a first salt as a main component and a second salt as an additive component, and is typically contained as an electrolyte in a battery.

[0028] (1) First Salt The first salt is a LiAl halide salt containing at least LiAlCl4. The first salt may contain only LiAlCl4, or may contain other compounds (other salts). In other words, the first salt may be a salt consisting of two or more types of salts. The first salt may also be a eutectic salt.

[0029] The proportion of LiAlCl4 in the first salt is, for example, 10 mol% or more, or may be 20 mol% or more, 30 mol% or more, or 40 mol% or more. On the other hand, the proportion of LiAlCl4 may be 100 mol% or less. Furthermore, the proportion of LiAlCl4 may be 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, or 50 mol% or less.

[0030] An example of a salt other than LiAlCl4 is LiAlX4 (X is F, Br, or I). The salt other than LiAlCl4 may be one type or two or more types. Among these, LiAlI4 is preferred.

[0031] The LiAl halide-based molten salt contains the first salt as a main component. The "main component" refers to a component contained in the LiAl halide-based molten salt at a ratio of 50 mol% or more. The ratio of the first salt may be 60 mol% or more, or may be 70 mol% or more. On the other hand, the ratio of the first salt is, for example, 95 mol% or less, or may be 90 mol% or less, or may be 80 mol% or less.

[0032] (2) Second Salt The second salt is an ionic liquid. An ionic liquid is a liquid salt having a cation component and an anion component, and refers to a salt that is liquid at, for example, 100°C or less. The ionic liquid may be a monocationic ionic liquid having one cation structure, or a dicationic ionic liquid having two cation structures. In a dicationic ionic liquid, the two cation structures may be the same or different. Note that the second salt in the present disclosure does not generally fall under the category of a LiAl halide salt.

[0033] Examples of the cationic component include methyldiethylsulfonium (S 122 ) and tetraethylsulfonium (S 222 ), sulfonium cations such as N-methyl-N-methoxymethylpyrrolidinium (P 1(101) ) and N-methyl-N-propylpyrrolidinium (P 13 ), pyrrolidinium cations such as 1-propyl-3-methylpyridinium (1Pr-3Me-Py), ammonium cations such as tetrahexylammonium (THA), and metal ions such as lithium ions. 1 (R 2 )(R 3 )S + ;R 1 ~R 3 are each hydrogen or an organic group. ) refers to a cation having the formula (I). Similarly, "pyrrolidinium-based," "pyridinium-based," and "ammonium-based" refer to cations having a pyrrolidinium group, a pyridinium group, and an ammonium group, respectively. The second salt may contain one type of cation, or may contain two or more types of cations.

[0034] Among the above cationic components, sulfonium-based cations, pyrrolidinium-based cations, and pyridinium-based cations are preferred because they have a large molecular weight and are bulky. It is believed that if the second salt contains a bulky cationic component, the interaction between Li and Al halide anions in the first salt can be weakened, resulting in a LiAl halide-based molten salt with better ionic conductivity.

[0035] Examples of the anion component include sulfonylamide anions such as bis(trifluoromethanesulfonyl)amide (TFSA), bis(fluorosulfonyl)amide (FSA), and fluorosulfonyl(trifluoromethanesulfonylamide) (FTA); sulfate anions such as hydrogen sulfate; and halogen ions such as chloride. Examples of the anion component also include boron fluoride anion, phosphorus fluoride ion, and trifluoromethanesulfonate. The second salt may contain one type of anion component or two or more types of anion components.

[0036] As the anion component, a sulfonylamide anion is preferred because it has a large molecular weight and is bulky. It is presumed that the bulky anion component can weaken the interaction between the Li and Al halide anions in the first salt.

[0037] The second salt may be one type of salt, or may be a salt composed of two or more types of salts.

[0038] The LiAl halide-based molten salt contains the second salt (ionic liquid) as an additive component. The "additive component" refers to a component contained in the LiAl halide-based molten salt in a proportion less than that of the first salt, which is the main component.

[0039] The proportion of the second salt in the LiAl halide-based molten salt is, for example, 5 mol% or more, or may be 10 mol% or more, 15 mol% or more, or 20 mol% or more, while the proportion of the second salt is, for example, 40 mol% or less, or may be 35 mol% or less, or may be 30 mol% or less, or may be 25 mol% or less.

[0040] In the LiAl halide-based molten salt, the ratio of the second salt to the first salt is, for example, 5 mol % or more and 45 mol % or less.

[0041] (3) LiAl halide molten salt The melting point of the LiAl halide molten salt is, for example, 100°C, and may be 80°C or lower, 70°C or lower, 60°C or lower, or 50°C or lower. On the other hand, the melting point is, for example, 10°C or higher, 20°C or higher, 30°C or higher, or 40°C or higher. The melting point can be determined, for example, by differential scanning calorimetry (DSC measurement).

[0042] The ionic conductivity of the LiAl halide molten salt (ionic conductivity at 25°C) is not particularly limited, but is preferably high. The ionic conductivity is, for example, 4.5 × 10 -5 S / cm or more, 4.9 × 10 -5 S / cm or more, and 1.0 × 10 -4 S / cm or more, and 3.0 × 10 -4 S / cm or more, and 5.0 × 10 -4 On the other hand, the ionic conductivity may be, for example, 4.0×10 -3 S / cm or less, 3.4 × 10 -3 S / cm or less, and 3.0 × 10 -3 S / cm or less, and 2.0 × 10 -3 S / cm or less, and 1.5 × 10 -3 The ionic conductivity may be determined by, for example, an AC impedance method.

[0043] In the battery, the LiAl halide-based molten salt is contained in at least one of the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer. The LiAl halide-based molten salt may be contained only in the positive electrode active material layer, only in the negative electrode active material layer, or only in the electrolyte layer. The LiAl halide-based molten salt may also be contained in any two of the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer, or in all three. In particular, in the battery of the present disclosure, the LiAl halide-based molten salt is preferably contained in the negative electrode active material layer. Here, the LiAl halide-based molten salt may be used in combination with another electrolyte in the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer. The other electrolyte will be described later.

[0044] The LiAl halide molten salt can be prepared by the method described in the Examples.

[0045] 2. Positive electrode active material layer The positive electrode active material layer contains at least a positive electrode active material.

[0046] The positive electrode active material may be, for example, an oxide active material. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and LiNi 0.8 Co 0.15 Al 0.05 Examples of the active material include rock salt layer type active materials such as O2, spinel type active materials such as LiMn2O4, and olivine type active materials such as LiFePO4. Sulfur (S) may also be used as the positive electrode active material.

[0047] The positive electrode active material is, for example, in the form of particles. 50 ) is, for example, 0.5 μm or more and 50 μm or less. 50 ) refers to the volume cumulative particle size measured by a laser diffraction / scattering particle size distribution analyzer. The proportion of the positive electrode active material in the positive electrode active material layer is, for example, 50% by weight or more and 80% by weight or less.

[0048] The positive electrode active material layer may contain at least one of an electrolyte, a conductive material, and a binder, as necessary. The positive electrode active material layer may or may not contain the LiAl halide-based molten salt described above as the electrolyte. The positive electrode active material layer may contain only a LiAl halide-based molten salt as the electrolyte, or may contain a LiAl halide-based molten salt and other electrolytes. The electrolyte will be described in "4. Electrolyte Layer."

[0049] Examples of the conductive material include carbon materials. Examples of the carbon material include particulate carbon materials such as acetylene black (AB) and ketjen black (KB), and fibrous carbon materials such as carbon fiber, carbon nanotubes (CNT), and carbon nanofibers (CNF). The proportion of the conductive material in the positive electrode active material layer is, for example, 0.01% by weight or more and 10% by weight or less.

[0050] Examples of binders include rubber-based binders such as butadiene rubber (BR), acrylate butadiene rubber (ABR), and styrene butadiene rubber (SBR), as well as fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). The proportion of the binder in the positive electrode active material layer is, for example, 0.5% by weight or more and 10% by weight or less.

[0051] The thickness of the positive electrode active material layer is not particularly limited, but is, for example, 0.1 μm or more and 1000 μm or less.

[0052] 3.Negative electrode active material layer The negative electrode active material layer contains at least a negative electrode active material.

[0053] Examples of negative electrode active materials include Si-based active materials. Si-based active materials are active materials containing Si element. Examples of Si-based active materials include simple Si, Si alloys, and Si oxides. The Si alloy preferably contains Si element as a main component. The proportion of Si element in the Si alloy is, for example, 50 mol% or more, or may be 70 mol% or more, or even 90 mol% or more. On the other hand, the proportion of Si element in the Si alloy is, for example, 99 mol% or less. Examples of Si alloys include Si-Al based alloys, Si-Sn based alloys, Si-In based alloys, Si-Ag based alloys, Si-Pb based alloys, Si-Sb based alloys, Si-Bi based alloys, Si-Mg based alloys, Si-Ca based alloys, Si-Ge based alloys, and Si-Pb based alloys. The Si alloy may be a binary alloy or a multi-component alloy of 3 or more components. Examples of Si oxides include SiO.

[0054] The Si-based active material may have a diamond-type crystalline phase, a clathrate I crystalline phase, or a clathrate II crystalline phase. In the clathrate I or II crystalline phase, multiple Si elements form a polyhedron (cage) containing pentagons or hexagons. This polyhedron has spaces inside that can encapsulate metal ions such as Li ions, thereby suppressing volumetric changes during charging and discharging. The Si-based active material may also have voids inside the primary particles. These voids can suppress volumetric changes in the active material and cracking of the negative electrode active material layer. The porosity is not particularly limited, but is, for example, 4% or more and 40% or less. The presence of voids in the primary particles and the porosity can be confirmed by observation with a scanning electron microscope (SEM).

[0055] The negative electrode active material layer may contain at least one of an electrolyte, a conductive material, and a binder, as necessary. The negative electrode active material layer may or may not contain the above-mentioned LiAl halide-based molten salt as the electrolyte, but the former is preferred. The negative electrode active material layer may contain only a LiAl halide-based molten salt as the electrolyte, or may contain a LiAl halide-based molten salt and other electrolytes. The electrolyte, LiAl halide-based molten salt, conductive material, and binder are the same as those described in "2. Positive electrode active material layer."

[0056] The thickness of the negative electrode active material layer is not particularly limited, but is, for example, 0.1 μm or more and 1000 μm or less.

[0057] 4. Electrolyte layer The electrolyte layer contains at least an electrolyte. The electrolyte layer may or may not contain the above-mentioned LiAl halide-based molten salt as the electrolyte. The electrolyte layer may contain only the LiAl halide-based molten salt as the electrolyte, or may contain the LiAl halide-based molten salt and other electrolytes.

[0058] In the electrolyte layer, the proportion of the LiAl halide molten salt to the total electrolyte may be 100% by weight or less, and in the latter case, the proportion is, for example, 10% by weight or more and 80% by weight or less.

[0059] The electrolyte layer may contain an electrolyte other than a LiAl halide-based molten salt. Examples of the electrolyte include solid electrolytes. Examples of the solid electrolyte include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes. The sulfide solid electrolyte preferably contains sulfur (S) as the main anion element. The oxide solid electrolyte preferably contains oxygen (O) as the main anion element. The halide solid electrolyte preferably contains halogen as the main anion element. Among these, the sulfide solid electrolyte is preferred.

[0060] The sulfide solid electrolyte preferably contains Li, M (wherein M is at least one of P, Sn, Al, Zn, In, Ge, Si, Sb, Ga, and Bi), and S. The sulfide solid electrolyte may also contain a halogen element such as F, Cl, Br, or I. In the sulfide solid electrolyte, a portion of the S element may be substituted with O.

[0061] The sulfide solid electrolyte may be a glass-based (amorphous) sulfide solid electrolyte, a glass-ceramic sulfide solid electrolyte, or a crystalline sulfide solid electrolyte. Examples of the crystalline phase contained in the sulfide solid electrolyte include an LGPS-type crystalline phase, a Thio-LISICON-type crystalline phase, and an argyrodite-type crystalline phase.

[0062] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-GeS2, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-P2S5-LiI-LiBr, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z m S n (where m and n are positive numbers. Z is Ge, Zn, or Ga.), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (where x and y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In.)

[0063] The electrolyte layer may contain a binder as needed, which is the same as that described in "2. Positive electrode active material layer."

[0064] The thickness of the electrolyte layer is not particularly limited, but is, for example, 0.1 μm or more and 1000 μm or less.

[0065] 5. Other configurations As shown in Fig. 1, a battery 10 according to the present disclosure typically includes a positive electrode current collector 4 that collects electrons from a positive electrode active material layer 1 and a negative electrode current collector 5 that collects electrons from a negative electrode active material layer 2. Examples of materials for the positive electrode current collector include stainless steel, aluminum, nickel, iron, titanium, and carbon. Examples of materials for the negative electrode current collector include stainless steel, copper, nickel, and carbon.

[0066] The battery according to the present disclosure may also include an exterior body that houses the above-described components. Examples of the exterior body include a laminate-type exterior body and a case-type exterior body. The battery according to the present disclosure may also include a restraining jig that applies a restraining pressure in the thickness direction to the above-described components. A known jig can be used as the restraining jig. The restraining pressure may be, for example, 0.1 MPa or more and 50 MPa or less, or 1 MPa or more and 20 MPa or less.

[0067] 6.Battery The battery in the present disclosure is typically a lithium ion secondary battery. The battery in the present disclosure may be a liquid battery or a solid-state battery. Here, when the electrolyte layer in the battery contains an electrolyte that is solid at room temperature (e.g., an inorganic solid electrolyte), the battery can be considered a solid-state battery. The solid-state battery may be a semi-solid-state battery or an all-solid-state battery. When the electrolyte layer in the battery contains an electrolyte that is solid at room temperature and an electrolyte that is liquid at room temperature (e.g., a molten salt), the battery can be considered a semi-solid-state battery. When the electrolyte layer in the battery contains only an electrolyte that is solid at room temperature, the battery can be considered an all-solid-state battery.

[0068] Examples of applications of the battery include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered automobiles, diesel-powered automobiles, etc. The battery of the present disclosure may also be used as a power source for mobile objects other than vehicles (for example, trains, ships, and aircraft), or as a power source for electrical appliances such as information processing devices.

[0069] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Example]

[0070] [Example 1] (Preparation of First Salt) A total of 10 g of LiCl and AlCl3 were weighed as raw materials, and 100 g of heptane was weighed. These were placed in a Fritsch ball mill (size: 500 ml, balls used: ZrO2) and ball milled at 300 rpm for 20 hours. This yielded LiAlCl4. LiAlI4 was obtained in a similar manner using LiI and AlI3 as raw materials. LiAlCl4 and LiAlI4 were mixed in a molar ratio of 20:80. This yielded the first salt (LiAl halide eutectic salt: 20LiAlCl4-80LiAlI4).

[0071] (Preparation of molten salt) As the second salt, the cationic component methyldiethylsulfonium (S 122 ) and the anionic component bis(trifluoromethanesulfonyl)amide (TFSA) as an ionic liquid (S 122TFSA) was prepared. The first salt and the second salt were mixed in a screw bottle. Then, a hot stirrer was used to heat and stir the mixture to 160°C, thereby obtaining a uniform molten compound (molten salt). The first salt and the second salt were added in amounts such that the proportion of the second salt in the molten salt was 30 mol %. The obtained molten salt was used as a sample and evaluated as described below.

[0072] [Examples 2 to 21] As shown in Table 1, a molten salt was obtained in the same manner as in Example 1, except that at least one of the type of the first salt, the type of the second salt, and the proportion of the second salt was changed.

[0073] [Comparative Examples 1 to 6] No second salt was used, and the salts shown in Table 1 were prepared as samples.

[0074] [Comparative Examples 7 to 9] A salt not containing LiAlCl4 (LiAlI4) and a second salt shown in Table 1 were prepared, and a molten salt (sample) was prepared in the same manner as in Example 1 using the proportions shown in Table 1.

[0075] [evaluation] (Melt point measurement) The melting points were determined by DSC measurement. Specifically, each sample was placed in an aluminum pan and sealed. The pan was heated from -100°C to 100°C at a rate of 5°C / min using a NETZSCH ultra-low temperature DSC measurement device (DSC-200 F3). The inflection point of the endothermic change indicating melting was determined from the obtained profile. Meanwhile, for samples in which no inflection point of the endothermic change was observed up to 100°C (high-melting-point samples), the sample was heated from room temperature to 200°C at a rate of 5°C / min using a Shimadzu measurement device (DSC-60). The inflection point of the endothermic change indicating melting was determined from the obtained profile. The results are shown in Table 1.

[0076] (Measurement of ionic conductivity) The ionic conductivity was determined by impedance measurement. Specifically, each sample was first melted to a liquid state. The liquid sample was filled into a battery evaluation batch cell (SB1A) manufactured by EC Frontier, and impedance measurement was performed at 25°C. The ionic conductivity was calculated from the obtained resistance value and shape factor. The results are shown in Table 1.

[0077] [Table 1]

[0078] As shown in Table 1, the LiAl halide molten salt in the present disclosure has an ionic conductivity of 4.9 × 10 -5 The ionic conductivity was 1.5 S / cm or higher, indicating better ionic conductivity than the comparative examples. This indirectly demonstrated that the battery resistance was suppressed in the battery containing the LiAl halide-based molten salt of the present disclosure. In Table 1, the samples of Examples 2, 4, 6, and 19 were in a supercooled state in the DSC measurement, but their melting points are presumed to be near room temperature. [Explanation of symbols]

[0079] 1...Cathode active material layer 2...Negative electrode active material layer 3...electrolyte layer 4...Positive electrode current collector 5...Negative electrode current collector 10...battery

Claims

1. A battery having a positive electrode active material layer, a negative electrode active material layer, and an electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, at least one of the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer contains a LiAl halide-based molten salt; The LiAl halide-based molten salt contains a first salt as a main component and a second salt as an additive component, The first salt is LiAlCl ４ A LiAl halide salt containing at least the second salt is an ionic liquid.

2. 2. The battery according to claim 1, wherein a ratio of the second salt in the LiAl halide-based molten salt is 10 mol % or more and 30 mol % or less.

3. The first salt is LiAlCl ４ and LiAlI ４ Including, The LiAlCl in the first salt ４ 2. The battery according to claim 1, wherein the ratio of is 20 mol % or more and 60 mol % or less.

4. 2. The battery according to claim 1, wherein the second salt contains, as a cationic component, at least one of a sulfonium-based cation, a pyrrolidinium-based cation, a pyridinium-based cation, an ammonium-based cation, and a metal ion.

5. 5. The battery of claim 4, wherein the cationic component is at least one of methyldiethylsulfonium, tetraethylsulfonium, N-methyl-N-methoxymethylpyrrolidinium, N-methyl-N-propylpyrrolidinium, and 1-propyl-3-methylpyridinium.

6. The battery according to claim 1 , wherein the second salt contains, as an anion component, at least one of a sulfonylamide-based anion, a sulfate-based anion, and a halogen ion.

7. 7. The battery of claim 6, wherein the anion component is at least one of bis(trifluoromethanesulfonyl)amide, bis(fluorosulfonyl)amide, and fluorosulfonyl(trifluoromethanesulfonylamide).

8. 2. The battery according to claim 1, wherein the melting point of the LiAl halide-based molten salt is 10°C or higher and 70°C or lower.

9. The ionic conductivity of the LiAl halide molten salt at 25°C is 4.9 × 10 －５ 2. The battery according to claim 1, wherein the electrical conductivity is 1.5 S / cm or more.

10. The ionic conductivity of the LiAl halide molten salt at 25°C is 3.4 × 10 －３ 2. The battery of claim 1, wherein the electrical conductivity is 0.05 S / cm or less.

11. The battery according to claim 1 , wherein the negative electrode active material layer contains the LiAl halide-based molten salt.

12. The battery of claim 1 , wherein the battery is a solid-state battery.

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