JP2021150037A - Lithium ion conductor - Google Patents

Abstract

To provide a lithium ion conductor that exhibits higher plasticity and higher ionic conductivity than a polymer while being solid.SOLUTION: A lithium ion conductor includes at least one lithium salt and at least one closed-shell hollow molecule, and the number of elements constituting the closed-shell hollow molecule is 12 or more and 100 or less, and the molecular weight of the closed-shell hollow molecule is 100 or more and 1000 or less, and the closed-shell hollow molecule is a nonionic molecule, and includes 30 mass% or more of the closed-shell hollow molecule with respect to 100 mass% of lithium ion conductor.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lithium ion conductor.

Lithium-ion secondary batteries are characterized by their light weight, high energy and long life, and are widely used as a power source for portable electronic devices such as notebook computers, mobile phones, digital cameras and video cameras. There is. In addition, with the transition to a society with a low environmental load, lithium-ion secondary batteries are used as power sources for hybrid electric vehicles (HEVs) and plug-in HEVs (Plug-in Hybrid Electric Vehicles: PHEVs), as well as housing. It is also attracting attention in the field of power storage such as power storage systems.

By the way, conventionally, an organic electrolytic solution in which a lithium salt is dissolved in an organic solvent has been used as an electrolyte of a lithium ion secondary battery, and there is a concern about safety due to leakage.

By using a solid electrolyte instead of the electrolyte, an all-solid-state battery in which the positive electrode material, electrolyte, and negative electrode material are all solids eliminates the need for a flammable electrolyte and dramatically improves safety. Proposed.

As the oxide-based solid electrolyte used in the all-solid-state battery, for example, an attempt has been made to use a metal oxide-based material such as a garnet-type oxide, a NASICON-type or a perovskite-type oxide as the solid electrolyte. These metal oxide-based materials have lithium ion conductivity and are chemically stable, but have a problem that they are hard and have poor moldability. On the other hand, there is a disclosure of a technique using a sulfide-based material because of its high lithium ion conductivity. However, the sulfide-based material has poor chemical stability, and when hydrogen sulfide is generated when exposed to the atmosphere, or when the sulfide-based solid electrolyte and the positive electrode material are brought into direct contact with each other, there is no lithium at the interface, and the thickness is high. There are problems such as the appearance of a "deficient layer" of several nanometers and a significant decrease in output characteristics. Sulfide-based materials have the advantage of being easier to mold than metal oxide materials, but their press pressure is high and short circuits are likely to occur during pressurization. Therefore, it is necessary to secure a certain thickness or more for the sulfide-based solid electrolyte, and there is a problem from the viewpoint of increasing the electric capacity as a battery by thinning the solid electrolyte layer and increasing the filling amount of the active material.

In response to the above problems, solid-state polymer electrolytes are also attracting attention, but it is difficult for an all-solid-state battery to which a solid polymer electrolyte is applied to exhibit sufficient output or capacity not only at room temperature but also at 60 ° C to 80 ° C. Reasons for this include, first, the low ionic conductivity of the polymer electrolyte, and then the interfacial resistance between lithium and the polymer electrolyte. Many efforts have been made to solve the problem of ionic conductivity of polymer electrolytes, but there has been no breakthrough improvement in ionic conductivity, and it has been pointed out as the limit of solid polymer electrolytes. ..

For example, Patent Document 1 is mentioned for the purpose of providing a polymer electrolyte for an all-solid-state battery in which the interfacial resistance between lithium and a solid polymer electrolyte is remarkably lowered, but the ionic conductivity has not been improved.

Special Table 2018-514929

A material with sufficient plasticity is required to reduce the interfacial resistance between lithium and the solid electrolyte. On the other hand, if the plasticity of the material is increased too much, it will flow, and there will be no difference from the so-called already commonly used organic electrolyte. Therefore, an object of the present invention is to provide a lithium ion conductor capable of exhibiting higher plasticity and higher ionic conductivity than a polymer while being a solid, and a non-aqueous secondary battery containing the same.

The present inventors wondered how to improve the ionic conductivity and improve the contact between the solid electrolyte and the active material of the electrode while maintaining the solid state, and have certain design requirements for the molecule. It was found that by using this molecule as a lithium ion conductor, the contact between the solid electrolyte and the electrode active material can be improved without fluidity, and the ionic conductivity can be improved, and the present invention is completed. I let you. One aspect of the present invention is illustrated below.

[1] The number of elements constituting the closed-shell hollow molecule, which contains at least one lithium salt and at least one closed-shell hollow molecule, is 12 or more and 100 or less, and the molecular weight of the closed-shell hollow molecule is It is a lithium ion conductor of 100 or more and 1,000 or less, the closed-shell hollow molecule is a nonionic molecule, and the closed-shell hollow molecule is 30% by mass with respect to 100% by mass of the lithium ion conductor. Lithium ion conductor including the above.
[2] The lithium ion conductor according to item 1, wherein the closed-shell hollow molecule includes one body-centered substantially spherical portion and at least one peripheral outer substantially spherical convex portion or outer peripheral substantially spherical concave portion.
[3] The fan closest to the center of gravity in the atomic arrangement of the closed-shell hollow molecule found based on the crystal structure analysis and the body-centered spherical portion of the closed-shell hollow molecule drawn based on the van der Waals radius. When the distance between the point of the Delwars drawing and the center of gravity is S1 and the distance between the point of the Van der Waals drawing farthest from the center of gravity and the center of gravity is S2, S1 / S2 is 0.6 or more and 1.0 or less. Item 2. The lithium ion conductor according to item 2.
[4] The lithium salt is represented by Li ₂ B ₁₀ H _10-a X _a [in the formula, X is selected from F, Cl, Br, or I, and a is an integer of 0 to 10]. LiCB ₁₂ H _12-b Y _b [In the formula, Y is selected from F, Cl, Br, or I, and b is an integer of 0 to 12], LiCB ₁₁ H _12-c Z _c [In the formula, Z is selected from F, Cl, Br, or I, and c is an integer of 0 to 12] LiCB ₉ H _10-d W _d [In the formula, X is selected from F, Cl, Br, or I, and d is an integer of 0 to 10], a lithium salt represented by LiN (SO ₂ F) ₂ , LiN (SO ₂ CF _3). ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , or a combination thereof, according to any one of items 1 to 3.
[5] The closed-shell hollow molecule is selected from the group consisting of ortho-carborane, meta-carborane, para-carborane, 2-adamantanone, 1-adamantanone, 1-adamantanane carbonitrile, and 2-adamantanane carbonitrile. The lithium ion conductor according to any one of items 1 to 3, which is at least one.
[6] A non-aqueous secondary battery containing the lithium ion conductor according to any one of items 1 to 5.

When the lithium ion conductor of the present invention is applied to an all-solid-state battery, the interface resistance with the electrode active material and the discharge overvoltage are remarkably reduced, and as a result, a sufficient discharge capacity is realized, and the output characteristics and energy density are improved. It can be improved.

It is a top view which shows typically an example of the structure of the non-aqueous secondary battery using the lithium ion conductor which concerns on one Embodiment of this invention. FIG. 5 is a cross-sectional view taken along the line AA of the non-aqueous secondary battery of FIG.

An example of the non-aqueous secondary battery of this embodiment is shown in FIGS. 1 and 2. FIG. 1 is a plan view schematically showing an example of the non-aqueous secondary battery, and FIG. 2 is a cross-sectional view taken along the line AA of FIG.

The non-aqueous secondary battery 100 has a positive electrode 150 and a negative electrode 160 in a region 120 of a laminated film exterior 110 composed of two aluminum laminated films, and a layer containing a lithium ion conductor (lithium ion conductor layer). It is formed by accommodating a laminated electrode body formed by laminating via 170. The aluminum laminated film exterior body 110 is sealed at the outer peripheral portion thereof by heat-sealing the upper and lower aluminum laminated films. The region 120 is a part of the exterior body 110 and is an inflated space for accommodating a laminate composed of a positive electrode 150, a negative electrode 160, and a lithium ion conductor layer 170.

The positive electrode 150 and the negative electrode 160 are electrically connected to an aluminum tab 130 and a nickel tab 140 for connection with an external circuit, respectively. In FIG. 2, in order to avoid complicating the drawings, the layers constituting the aluminum laminated film exterior 110 and the layers of the positive electrode 150 and the negative electrode 160 are not shown separately. In the non-aqueous secondary battery 100, as each member other than the lithium ion conductor, those provided in the conventional lithium ion secondary battery can be used, and for example, those described later may be used. It is desirable that the lithium ion conductor layer 170 has a separator from the viewpoint of preventing a short circuit, but even in an embodiment without the separator, it is possible to exhibit the excellent effects of the present invention.

In the non-aqueous secondary battery 100, pressure may be applied in the region 120. The components of the non-aqueous secondary battery will be described below.

<1. Lithium-ion conductor>
The lithium ion conductor in the present embodiment contains at least one lithium salt and at least one closed-shell cavity-like molecule, and the number of elements constituting the closed-shell cavity-like molecule is 12 or more and 100 or less, and the closed-shell cavity is formed. The molecular weight of the state molecule is not particularly limited as long as it is a lithium ion conductor having a molecular weight of 100 or more and 1000 or less.

<1-1. Closed-shell hollow molecule>
In the present embodiment, an element having at least four vertices and forming a three-dimensional structure is defined as a "closed shell", and a closed-shell hollow molecule has a closed shell, and a space exists inside the closed shell. Refers to the molecule that does. The shape of the three-dimensional structure of the closed-shell hollow molecule is, for example, a triangular pyramid, a cube, or a regular n-plane, and the atomic radius of the element does not limit the three-dimensional symmetry of the three-dimensional structure.

The number of elements constituting the closed-shell hollow molecule is 12 or more and 100 or less. From the viewpoint of stability as a solid, the lower limit of the number of elements is determined, and from the viewpoint of enhancing the motility of the molecule, the upper limit is determined. That is, the number of elements constituting the closed-shell hollow molecule is preferably 12 or more and 60 or less, more preferably 20 or more and 60 or less, and preferably 20 or more and 40 or less. ..

The molecular weight of the closed-shell hollow molecule is 100 or more and 1,000 or less. From the viewpoint of stability as a solid, the lower limit of the molecular weight is preferably 110 or more, more preferably 120 or more. The upper limit of the molecular weight is preferably 900 or less, more preferably 800 or less, from the viewpoint of enhancing the motility of the molecule.

The closed-shell hollow molecule according to the present embodiment preferably has a viscosity of 30 Pa · s or more at room temperature (25 ° C.). Further, the closed-shell hollow molecule is preferably nonionic.

The closed-shell hollow molecule according to the present embodiment preferably includes one body-centered substantially spherical portion and at least one peripheral outer substantially spherical convex portion or at least one peripheral outer substantially spherical concave portion. That is, the center of gravity of the substantially spherical portion of the body center and the center of gravity of at least one outer peripheral convex portion or outer peripheral concave portion do not coincide with each other.

In the closed-shell hollow molecule, the number of peripheral convex portions or peripheral concave portions may be one or more, preferably one or more and three or less, and more preferably one or more and two or less.

When the number of the outer peripheral convex portion or the outer peripheral concave portion is one, the arrangement may be as long as it is on the substantially spherical portion of the body center, and the arrangement is not restricted. Even when the number of the peripheral convex portions or the peripheral concave portions is two, it suffices as long as it is on the body-centered spherical portion, and the arrangement thereof is not restricted. When the number is preferably two, it is preferable that the hemisphere has two outer convex portions or outer peripheral concave portions when the body heart sphere is halved. In the case of the three cases of the outer peripheral convex portion and the outer peripheral concave portion, it suffices as long as it is on the substantially spherical portion of the body center, and the arrangement thereof is not restricted. When the number is preferably three, it is preferable that when the body heart sphere is halved, the hemisphere has two outer spheres and the other outer sphere is in the opposite hemisphere.

When a closed-shell hollow molecule is drawn based on the van der Waals radius, the ratio of the volume of the body-centered sphere to the volume of the peripheral convex or concave is the volume of the body-centered sphere (V1) and the volume of the outer convex. Alternatively, when the volume of the recess (V2) is set, it is preferable that V1 / V2 is smaller than 1. For the depiction of the closed-shell hollow molecule, the atomic arrangement found by the crystal structure analysis and "Bondi A (1964) Journal of Physical Chemistry 68: 441-" regarding the van der Waals radius are used.

When a closed-shell hollow molecule is imaged based on the atomic arrangement found by crystal structure analysis and the van der Waals radius, the distance between the point of the van der Waals image closest to the center of gravity and the center of gravity is S1 in the body-centered approximate sphere. Assuming that the distance between the van der Waals image point farthest from the center of gravity and the center of gravity is S2, S1 / S2 is preferably 0.6 or more and 1.0 or less, and S1 / S2 is 0.7 or more and 1 More preferably, it is 0.0 or less.

The closed-shell hollow molecule according to the present embodiment contains different element ratios between the substantially spherical portion of the body and the outer circumference. The element ratio refers to the ratio of the elements that make up each part.

The average electronegativity of the convex outer sphere or the concave outer sphere is greater than the average electronegativity of the convex outer sphere or the concave outer sphere, regardless of the number of convex or outer spheres. Is preferable. As the average electronegativity, a value obtained by adding the electronegativity of the elements constituting the substantially spherical portion and dividing by the number of elements is used.

Examples of the closed-shell hollow molecule according to the present embodiment include ortho-carborane, meta-carborane, para-carborane, 2-adamantanone, 1-adamantanone, 1-adamantanane carbonitrile, 2-adamantanane carbonitrile, and the like. However, this is not the case.

The above-mentioned closed-shell hollow molecule can be produced by a known synthetic method, a synthetic method if necessary, or the like.

<1-2. Lithium salt>
The lithium salt contained in the lithium ion conductor in the present embodiment may be any lithium salt used in the electrolytic solution of the non-aqueous secondary battery.

The content of the lithium salt in the lithium ion conductor of the present embodiment is not particularly limited, but is preferably 0.2 mol or more, and more preferably 0.5 mol or more with respect to 1 L of the non-aqueous solvent. It is preferably 0.8 mol or more, and more preferably 0.8 mol or more. The content of the lithium salt is preferably 15 mol or less, more preferably 4 mol or less, and further preferably 2.8 mol or less with respect to 1 L of the non-aqueous solvent. When the content of the lithium salt is within the above range, the ionic conductivity tends to increase and high output characteristics can be exhibited, and the storage characteristics and other batteries can be maintained while maintaining the excellent performance of the lithium ion conductor. There is a tendency for the properties to be even better.

The lithium salt is not particularly limited as long as it is used as a normal non-aqueous electrolyte, and any lithium salt may be used. Specific examples of such lithium salts include, for example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , Li ₂ B ₁₀ H _10-a X _a [ In the formula, X is selected from F, Cl, Br, or I, and a is an integer of 0 to 10. Lithium salt, LiB ₁₂ H _12-b Y _b [In the formula, Y is F. , Cl, Br, or I, and b is an integer from 0 to _{12], LiCB 11} H _12-c Z _c [where Z is F, Cl, Br, or Lithium salt selected from I and c is an integer from 0 to 12], LiCB ₉ H _10-d W _d [In the formula, X is selected from F, Cl, Br, or I and d is an integer of 0 to 10] Lithium salt, LiN (SO ₂ F) ₂ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) _2, etc. LiN (SO ₂₎ C _m F _{2m + 1} ) ₂ Lithium salt represented by [in the formula, m is an integer of 1 to 8]; _{LiPF n} (C _p F _{2p + 1} ) _6-n such as LiPF ₅ (CF ₃ ) [in the formula, n is an integer of 1 to 5, and p is an integer of 1 to 8] Lithium salt; _{LiBF q} (C _s F _{2s + 1} ) _4-q [in the formula] such as LiBF ₃ (CF _3). , Q is an integer of 1 to 3 and s is an integer of 1 to 8]. Lithium salt represented by LiB (C ₂ O ₄ ) ₂ ; Lithium bis (oxalat) borate (LiBOB) represented by 2 Lithium salt of volate with a halogenated organic acid as a ligand; Lithium oxalatodifluoroborate (LiODFB) represented by _{LiBF 2} (C ₂ O _{4 ); LiB (C 3} O ₄ H ₂ ) ₂ Lithium bis (malonate) borate (LiBMB) _{represented; lithium salt such as lithium tetrafluorooxalatphosphate represented by LiPF 4} (C ₂ O ₄ ); the following general formulas (1a), (1b) and (1c) ):
LiC (SO ₂ R ² ) (SO ² R ³ ) (SO ₂ R ⁴ ) (1a)
LiN (SO ₂ OR ⁵ ) (SO ₂ OR ⁶ ) (1b)
LiN (SO ₂ R ⁷ ) (SO ₂ OR ⁸ ) (1c)
{In the formula, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ may be the same or different from each other, and may contain perfluoroalkyl groups having 1 to 8 carbon atoms. show. } Can be mentioned, such as lithium salts represented by each of. Among them, from the viewpoint of ionic conductivity, _{it is represented by Li 2} B ₁₀ H _10-a X _a [in the formula, X is selected from F, Cl, Br, or I, and a is an integer of 0 to 10]. Lithium salt, LiB ₁₂ H _12-b Y _b [In the formula, Y is selected from F, Cl, Br, or I, and b is an integer of 0 to 12], LiCB. ₁₁ H _12-c Z _c [In the formula, Z is selected from F, Cl, Br, or I, and c is an integer of 0 to 12] Lithium salt, LiCB ₉ H _10-d W _d [In the formula, X is selected from F, Cl, Br, or I, and d is an integer of 0 to 10] Lithium salt, LiN (SO ₂ F) ₂ , LiN (SO ₂ CF) ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ is preferably contained, and more preferably Li ₂ B ₁₀ H _10-a X _a [In the formula, X is selected from F, Cl, Br, or I. , And a is an integer of 0 to 10], LiB ₁₂ H _12-b Y _b [In the formula, Y is selected from F, Cl, Br, or I, and b is 0. Lithium salt represented by [an integer of ~ 12], LiCB ₁₁ H _12-c Z _c [In the formula, Z is selected from F, Cl, Br, or I, and c is an integer of 0 to 12. ], LiCB ₉ H _10-d W _d [In the formula, X is selected from F, Cl, Br, or I, and d is an integer of 0 to 10]. It preferably contains a salt. The lithium salt may be used alone or in combination of two or more.

<1-3. Non-aqueous solvent>
The lithium ion conductor of the present embodiment may consist only of the above-mentioned closed-shell hollow molecule and lithium salt, or may contain a non-aqueous solvent other than these.

The non-aqueous solvent in the present embodiment is not particularly limited as long as it does not hinder the solution of the problem according to the present invention. The non-aqueous solvent is preferably a substance that contributes to improving the performance of the lithium ion conductor and the non-aqueous secondary battery of the present embodiment. As the non-aqueous solvent, one component may be used alone or two or more components may be used in combination.

The other non-aqueous solvent added to the lithium ion conductor of the present embodiment is not particularly limited, and examples thereof include an aprotic solvent, and an aprotic polar solvent is preferable.

Specific examples of such a non-aqueous solvent include, for example, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, trans-2,3-butylene carbonate, cis-2,3-butylene carbonate, 1,2-penti. Cyclic carbonates typified by len carbonate, trans-2,3-pentylene carbonate, cis-2,3-pentylene carbonate, trifluoromethylethylene carbonate, fluoroethylene carbonate, and 1,2-difluoroethylene carbonate; γ- Lactones typified by butyrolactone and γ-valerolactone; sulfur compounds typified by sulfolane and dimethylsulfoxide; cyclic ethers typified by tetrahydrofuran, 1,4-dioxane, and 1,3-dioxane; methylethyl carbonate, dimethyl carbonate , Diethyl carbonate, methylpropyl carbonate, methylisopropyl carbonate, dipropyl carbonate, methylbutyl carbonate, dibutyl carbonate, ethylpropyl carbonate, and chain carbonates typified by methyltrifluoroethyl carbonate; propionitrile, butyronitrile, valeronitrile, Mononitrile represented by benzonitrile and acrylonitrile (excluding acetonitrile); alkoxy group-substituted nitrile represented by methoxynitrile and 3-methoxypropionitrile; chain carboxylic acid represented by methyl propionate. Esters: Chain ethers and the like represented by dimethoxyethane, and halides and the like represented by these fluorinated compounds can be mentioned. These may be used alone or in combination of two or more.

The content of the non-aqueous solvent in the lithium ion conductor of the present embodiment is not particularly limited, but is preferably 0.1 to 30% by mass with respect to the total amount of the lithium ion conductor of the present embodiment. More preferably, it is 0.1 to 10% by mass.

<1-4. Additives>
The lithium ion conductor of the present embodiment may consist only of the above-mentioned closed-shell hollow molecule and lithium salt, or may consist of only the above-mentioned closed-shell hollow molecule, the above-mentioned lithium salt and a non-aqueous solvent. However, additives other than these may be contained.

The additive in the present embodiment is not particularly limited as long as it does not hinder the solution of the problem according to the present invention, and is a substance (that is, the above-mentioned non-aqueous solvent) that plays a role as a solvent that dissolves and dissolves the lithium salt. It may be substantially duplicated. The additive is preferably a substance that contributes to improving the performance of the lithium ion conductor and the non-aqueous secondary battery of the present embodiment. However, the additive also includes substances that are not directly involved in the electrochemical reaction. As the additive, one component can be used alone or two or more components can be used in combination.

Examples of the additive include an additive that protects the electrode.

Specific examples of the additive include 4-fluoro-1,3-dioxolan-2-one, 4,4-difluoro-1,3-dioxolan-2-one, cis-4,5-difluoro-1, and so on. 3-Dioxolan-2-one, trans-4,5-difluoro-1,3-dioxolan-2-one, 4,4,5-trifluoro-1,3-dioxolan-2-one, 4,4,5 , 5-Tetrafluoro-1,3-dioxolan-2-one, and 4,4,5-trifluoro-5-methyl-1,3-dioxolan-2-one typified by fluoroethylene carbonate; vinylene carbonate, Unsaturated bond-containing cyclic carbonates typified by 4,5-dimethylvinylene carbonate and vinylethylene carbonate; to γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-valerolactone, δ-caprolactone, and ε-caprolactone. Represented lactone; cyclic ether typified by 1,2-dioxane;

Methylformate, methylacetate, methylpropionate, methylbutyrate, ethylformate, ethylacetate, ethylpropionate, ethylbutyrate, n-propylformate, n-propylacetate, n-propylpropionate, n-propylbutyrate, isopropylformate, isopropylacetate, isopropylpropionate, isopropylbutyrate, n-butylformate, n-butylacetate, n-butylpropionate, n-butylbutyrate, isobutylformate, Isobutylacetate, isobutylpropionate, isobutylbutyrate, sec-butylformate, sec-butylacetate, sec-butylpropionate, sec-butylbutyrate, tert-butylformate, tert-butylacetate, tert-butyl Propionate, tert-butylbutyrate, methylpivalate, n-butylpivalate, n-hexylpivalate, n-octylpivalate, dimethyloxalate, ethylmethyloxalate, diethyloxalate, diphenyloxalate, malonic acid ester. , Fumaric acid ester, and carboxylic acid ester represented by maleic acid ester;

Amides typified by N-methylformamide, N, N-dimethylformamide, and N, N-dimethylacetamide; ethylenesulfite, propylenesulfite, butylenesulfite, pentensulfite, sulfolane, 3-methylsulfolane, 3- Cyclic sulfur compounds typified by sulfolene, 1,3-propane sulton, 1,4-butane sulton, 1,3-propanediol sulfate ester, tetramethylene sulfoxide, and thiophene 1-oxide; monofluorobenzene, biphenyl, and fluorination. Examples thereof include aromatic compounds typified by biphenyl; nitro compounds typified by nitromethane; Schiff bases; Schiff base complexes; oxalate complexes. These may be used alone or in combination of two or more.

The content of the additive in the lithium ion conductor of the present embodiment is not particularly limited, but is preferably 0.1 to 30% by mass with respect to the total amount of the lithium ion conductor of the present embodiment, and is 0. .1 to 10% by mass is more preferable.

In the present embodiment, the higher the content of the additive, the more the deterioration of the lithium ion conductor is suppressed, but the lower the content of the additive, the better the high output characteristics of the non-aqueous secondary battery in a low temperature environment. become. Therefore, by adjusting the content of the additive within the above range, the excellent performance based on the high ionic conductivity of the lithium ion conductor is maximized without impairing the basic function as a non-aqueous secondary battery. Can be demonstrated. By preparing the electrolytic solution with such a composition, the cycle performance, the high output performance in a low temperature environment, and other battery characteristics are all further improved in the non-aqueous secondary battery provided with the lithium ion conductor. Can be.

<1-5. Other additives>
In the present embodiment, the lithium ion conductor is an additive for achieving various physical properties against battery manufacturing or aging deterioration such as handling or storage during manufacturing in addition to battery characteristics such as moldability or strength. May include. Examples of additives other than the additives described in 1-4 above include nonionic conductive polymers (PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polycarboxylic acid, polysulfonic acid, polyacrylic acid, etc. Styrene butadiene rubber, fluorine rubber, etc.), non-ionic conductive inorganic fillers (eg, TIO ₂ , SiO ₂ , BaTIO ₃ , Al ₂ O ₃ , boehmite, etc.), organic fibers (eg, polyethylene, polypropylene, cellulose, etc.), etc. Can be mentioned.

The content of other additives in the lithium ion conductor of the present embodiment is not particularly limited, but is preferably 0.1 to 30% by mass with respect to the total amount of the lithium ion conductor of the present embodiment. , 0.1 to 10% by mass, more preferably.

<2. Second Lithium Ion Conductor>
The lithium ion conductor of the present embodiment may be composed of only the above-mentioned closed-shell hollow molecule and the lithium salt, or may be composed of only the above-mentioned closed-shell hollow molecule, the above-mentioned lithium salt and a non-aqueous solvent. However, it may consist only of the above-mentioned closed-shell hollow molecule, the above-mentioned lithium salt, a non-aqueous solvent and an additive, or may contain a second lithium ion conductor other than these. As the second lithium ion conductor, a known polymer-based solid electrolyte, oxide-based solid electrolyte, or sulfide-based solid electrolyte may be combined. The content of the second lithium ion conductor in the lithium ion conductor of the present embodiment is not particularly limited. When the characteristics of the lithium ion conductor of the present embodiment are good, the content of the second lithium ion conductor is preferably 0.1 to 30% by mass, preferably 0.1 to 10% by mass. More preferably. When the characteristics of the lithium ion conductor to be combined are good, the content of the lithium ion conductor of the present embodiment is preferably 0.1 to 30% by mass, more preferably 0.1 to 10% by mass. preferable.

<3. Method for manufacturing lithium-ion conductors>
The method for producing a lithium ion conductor of the present invention is not limited to the present invention, and a mixing and molding step by a known wet or dry method may be used. For example, when a lithium ion conductor is produced by a wet method, the lithium ion conductor and the lithium salt are dissolved in a solvent, and a film is formed by a method such as doctor blade, die coating, comma coating, or screen printing. At this time, the concentration of the solution, the number of coatings, and the like can be adjusted to adjust the coating film thickness to be finally coated. The drying step is a step of removing the solvent and water in the lithium ion conductor coating film coated on the support, and varies depending on the solvent used. As an example, it is carried out in a vacuum oven at 50 to 200 ° C. Examples of the drying method include drying with warm air, hot air, low humidity air, vacuum drying, and drying with irradiation with (far) infrared rays or electron beams. The drying time is not particularly limited, but is usually carried out in the range of 30 seconds to 24 hours.

When a lithium ion conductor is produced by a dry method, it can be produced by extrusion molding a composition containing a suitable component in a suitable ratio. A uniaxial screw extruder or a twin screw extruder can be used to melt closed-shell hollow molecules, add a lithium salt, knead, and then extrude. It is preferably manufactured using a twin-screw extruder that allows for better dispersion.

With respect to the above-mentioned 1-4 additives, the above-mentioned 1-5 other additives, non-aqueous solvent, and the second lithium ion conductor, the timing of addition is appropriately adjusted in consideration of their productivity or storage stability. be able to.

<4. Positive electrode and positive electrode current collector>
The positive electrode is not particularly limited as long as it acts as a positive electrode of a non-aqueous secondary battery, and may be a known one. The preferred positive electrode in this embodiment contains a positive electrode active material, and optionally further contains a conductive aid, a binder and a lithium ion conductor.

It is preferable that the positive electrode contains one or more materials selected from the group consisting of materials capable of occluding and releasing lithium ions as the positive electrode active material because high voltage and high energy density tend to be obtained. Such materials include, for example, the following general formulas (2a) and (2b):
Li _x MO ₂ (2a)
Li _y M ₂ O ₄ (2b)
{In the formula, M represents one or more metals selected from transition metals, x represents a number 0 to 1, and y represents a number 0 to 2. }, Lithium-containing compounds represented by each, and other lithium-containing compounds can be mentioned.

Examples of the lithium-containing compound represented by each of the above general formulas (2a) and (2b) include lithium cobalt oxide represented by _{LiCoO 2 ; LiMnO 2} , LiMn ₂ O ₄ , and Li ₂ Mn ₂ O ₄ lithium manganese oxide represented by; lithium nickel oxide represented by LiNiO _{2; Li} z MO ₂ (where, M is, Ni, Mn, Co, 1 or more selected from the group consisting of Al and Mg Examples thereof include lithium-containing composite metal oxides represented by (Z indicates a number of more than 0.9 and less than 1.2).

The other lithium-containing compound may be any compound containing lithium. Examples of such other lithium-containing compounds include a composite oxide containing lithium and a transition metal element, a metal chalcogenide having lithium, a phosphoric acid compound containing lithium and a transition metal element, and lithium and a transition metal element. DOO silicic acid metal compound (e.g. _Li t _M u _SiO 4, _M has the same meaning as in the above formula (2a), t is the number of 0 to 1, u represents. a number of 0 to 2) include .. From the viewpoint of obtaining a higher voltage, other lithium-containing compounds include lithium, cobalt (Co), nickel (Ni), manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn). , A composite oxide containing one or more transition metal elements selected from the group consisting of chromium (Cr), vanadium (V) and titanium (Ti), and phosphoric acid compounds are preferred.

More specifically, as other lithium compounds, a composite oxide containing lithium and a transition metal element, a metal chalcogenide containing lithium and a transition metal element, and a metal phosphate compound having lithium are more preferable, and transition to lithium. A composite oxide containing a metal element and a metal phosphate compound having lithium are more preferable. For example, the following general formulas (3a) and (3b):
^{_{Li v M I O 2 (3a}} )
Li _w M ^II PO ₄ (3b)
{Wherein, ^{M I} and ^{M II} is represents one or more transition metal elements each, the value of v and w vary according to the charge and discharge state of the battery, v is .05-1.10, w is 0. Indicates a number from 05 to 1.10. } Can be mentioned.

The compound represented by the general formula (3a) has a layered structure, and the compound represented by the general formula (3b) has an olivine structure. These compounds are those in which a part of the transition metal element is replaced with Al, Mg, or other transition metal elements for the purpose of stabilizing the structure, or those in which these metal elements are contained in the grain boundaries. , A part of the oxygen atom is replaced with a fluorine atom or the like, or at least a part of the surface of the positive electrode active material is coated with another positive electrode active material.

As the positive electrode active material in the present embodiment, only the above-mentioned lithium-containing compound may be used, or other positive electrode active materials may be used in combination with the lithium-containing compound.

Examples of such other positive electrode active materials include metal oxides or metal chalcogenides having a tunnel structure and a layered structure; sulfur; conductive polymers and the like. Examples of metal oxides or metal chalcogenides having a tunnel structure and a layered structure include MnO ₂ , FeO ₂ , FeS ₂ , V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , TiS ₂ , MoS ₂ , and NbSe _2. Examples thereof include oxides, sulfides, and selenium compounds of metals other than lithium represented by.

Examples of the conductive polymer include conductive polymers typified by polyaniline, polythiophene, polyacetylene, and polypyrrole.
The positive electrode active material may be used alone or in combination of two or more.

When a lithium-containing compound and another positive electrode active material are used in combination as the positive electrode active material, the usage ratio of both is preferably 80% by mass or more, preferably 85% by mass, as the usage ratio of the lithium-containing compound to the total of the positive electrode active material. % Or more is more preferable.

The number average particle size (primary particle size) of the positive electrode active material is preferably 0.05 μm to 100 μm, and more preferably 1 μm to 10 μm. The number average particle size of the positive electrode active material can be measured by a wet particle size measuring device (for example, a laser diffraction / scattering type particle size distribution meter, a dynamic light scattering type particle size distribution meter, etc.). Alternatively, 100 particles are randomly extracted from the image observed using a transmission electron microscope and analyzed with image analysis software (for example, image analysis software manufactured by Asahi Kasei Engineering Co., Ltd., trade name "A image-kun"). It can also be obtained by calculating the additive average. In this case, if the number average particle size is different between the measurement methods for the same sample, a calibration curve prepared for the standard sample may be used.

Examples of the conductive auxiliary agent include graphite, acetylene black, carbon black typified by Ketjen black, and carbon fiber. The number average particle size (primary particle size) of the conductive auxiliary agent is preferably 10 nm to 10 μm, and more preferably 20 nm to 1 μm. The number average particle size of the conductive auxiliary agent is measured in the same manner as the number average particle size of the positive electrode active material. The content ratio of the conductive auxiliary agent is preferably 10 parts by mass or less, and more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the positive electrode active material.

Examples of the binder include PVDF, PTFE, polyacrylic acid, styrene-butadiene rubber, and fluororubber. The content ratio of the binder is preferably 6 parts by mass or less, and more preferably 0.5 to 4 parts by mass with respect to 100 parts by mass of the positive electrode active material.

The content ratio of the lithium ion conductor is preferably 25 parts by mass or less, and more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the positive electrode active material.

The positive electrode is obtained, for example, as follows. That is, first, a positive electrode mixture-containing slurry is prepared by dispersing a positive electrode mixture obtained by adding a conductive auxiliary agent, a binder, a lithium ion conductor, or the like to the positive electrode active material and mixing them in a solvent, if necessary. .. The solvent is not particularly limited, and conventionally known solvents may be used. Examples thereof include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, and water. Here, the solid content concentration in the positive electrode mixture-containing slurry is preferably 30 to 80% by mass, more preferably 40 to 70% by mass. Next, this positive electrode mixture-containing slurry is applied onto the positive electrode current collector and dried to form a positive electrode active material layer.

The positive electrode current collector is composed of, for example, a metal foil such as an aluminum foil, a nickel foil, or a stainless steel foil. The surface of the positive electrode current collector may be coated with carbon or may be processed into a mesh shape. The thickness of the positive electrode current collector is preferably 5 to 40 μm, more preferably 7 to 35 μm, and even more preferably 9 to 30 μm.

The positive electrode mixture layer (positive electrode) is formed by compressing the positive electrode active material layer obtained after drying by a roll press or the like. The thickness of the positive electrode mixture after compression is preferably 10 to 300 μm, more preferably 20 to 280 μm, and even more preferably 30 to 250 μm.

<5. Negative electrode and negative electrode current collector>
The negative electrode is not particularly limited as long as it acts as a negative electrode of a non-aqueous secondary battery, and may be a known one. The preferred negative electrode in the present embodiment contains a negative electrode active material, and optionally further contains a conductive auxiliary agent, a binder, and a lithium ion conductor.

The negative electrode preferably contains, as the negative electrode active material, a material capable of occluding and releasing lithium ions, and one or more materials selected from the group consisting of metallic lithium. Examples of such materials include metallic lithium, amorphous carbon (hard carbon), artificial graphite, natural graphite, thermally decomposed carbon, coke, glassy carbon, calcined material of organic polymer compound, mesocarbon microbeads, and carbon fiber. , Carbon materials typified by activated carbon, graphite, carbon colloid, and carbon black; materials containing elements capable of forming an alloy with lithium and the like. Examples of the coke include pitch coke, needle coke, and petroleum coke. The calcined product of the organic polymer compound is obtained by calcining a polymer material such as phenol resin or furan resin at an appropriate temperature to carbonize it. The carbon material, in addition to carbon, O, B, P, N , S, Si, SiC, SiO, such as _SiO 2, _{B 4} C, may include a different element or heterologous compound. The content of the dissimilar element or the dissimilar compound is preferably 0 to 10% by mass.

The material containing an element capable of forming an alloy with lithium may be a simple substance, an alloy, or a compound of a metal or a semimetal, and has at least one or more of these phases in a part thereof. It may be.

In the present specification, the "alloy" includes an alloy having two or more kinds of metal elements and one having one or more kinds of metal elements and one or more kinds of metalloid elements. Further, the alloy may contain a non-metallic element as long as it has metallic properties as a whole. A solid solution, a eutectic (eutectic mixture), an intermetallic compound, or two or more of these can coexist in the structure of the alloy.

Examples of metal elements and metalloid elements capable of forming an alloy with lithium include titanium (Ti), tin (Sn), lead (Pb), aluminum (Al), indium (In), silicon (Si), and zinc. (Zn), antimony (Sb), bismuth (Bi), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), hafnium (Hf), zirconium (Zr), and yttrium (Y) Can be mentioned. Among these, the metal elements and metalloid elements of Group 4 or Group 14 in the long periodic table are preferable. Particularly preferred are titanium, silicon, and tin, which have a high ability to occlude and release lithium and can obtain high energy densities.

As a tin alloy, as a second constituent element other than tin, for example, silicon, magnesium (Mg), nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium (Ti), germanium, bismuth, etc. Examples thereof include those having one or more elements selected from the group consisting of antimony and chromium (Cr).

As an alloy of silicon, as a second constituent element other than silicon, for example, from the group consisting of magnesium, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium. Those having one or more selected elements can be mentioned.

Examples of the titanium compound, the tin compound, and the silicon compound include those having oxygen (O) or carbon (C). In this case, in addition to titanium, tin, or silicon, it may have the above-mentioned second constituent element.

The negative electrode is 0.4 to 3 V vs. as the negative electrode active material. It may contain a metal compound capable of occluding lithium ions in the range of Li / Li ^+. Examples of such metal compounds include metal oxides, metal sulfides, and metal nitrides.

Examples of the metal oxide include titanium oxide, lithium titanium oxide (lithium titanium-containing composite oxide), tungsten oxide (for example, WO ₃ ), and amorphous tin oxide (for example, SnB _0.4 P _0.6 O _{3). .1} ), tin silicon oxide (eg SnSiO ₃ ), and silicon oxide (SiO). Among these, titanium oxide and lithium titanium oxide are preferable.

Examples of the lithium titanium oxide include lithium titanate having a spinel structure {for example, Li ₄ + aTi ₅ O ₁₂ (in the formula, a can change in the range of -1 ≦ a ≦ 3 depending on the charge / discharge reaction)}, Rams. Examples thereof include lithium titanate having a delight structure {for example, Li _{2 + bTi 3} O ₇ (in the formula, b can change in the range of -1 ≦ b ≦ 3 depending on the charge / discharge reaction)}.

As the titanium oxide, either one containing Li or one not containing Li can be used before charging / discharging. Examples of titanium oxides that do not contain Li before charging / discharging (during synthesis) include titanium oxide (for example, TIO ₂ , H ₂ Ti ₁₂ O ₂₅ ), Ti and P, V, Sn, Cu, Ni, and Fe. Examples thereof include titanium composite oxides containing at least one element selected from the group consisting of. The TiO ₂ is preferably an anatase type and has a low crystallinity with a heat treatment temperature of 300 to 500 ° C. The titanium composite oxide, _{e.g., TiO 2 -P 2 O 5,} TiO 2 -V 2 O 5, TiO 2 -P 2 O 5 -SnO 2, TiO 2 -P 2 O 5 -MeO ( wherein, Me Is at least one element selected from the group consisting of Cu, Ni and Fe). The titanium composite oxide preferably has a low crystallinity and has a microstructure in which a crystalline phase and an amorphous phase coexist or the amorphous phase alone exists. By having such a microstructure, the cycle performance of the non-aqueous secondary battery can be significantly improved.

Examples of the titanium oxide containing Li before charging / discharging (during synthesis) include Li _c TiO ₂ (in the formula, 0 <c ≦ 1.1) and the like.

Examples of the metal sulfide include titanium sulfide (for example, TiS ₂ ), molybdenum sulfide (for example, MoS ₂ ), and iron sulfide (for example, FeS, FeS ₂ , Li _g FeS ₂ (in the formula, g is 0 ≦ g ≦ 1). Is)). As the metal nitride, for example, lithium cobalt nitride _{(e.g., Li d Co e N, 0} <d <4,0 <e <0.5) can be mentioned.

In the non-aqueous secondary battery of the present embodiment, from the viewpoint that the battery voltage can be increased, the negative electrode uses 0.4 V vs. lithium ion as the negative electrode active material. It is preferable to contain a material that occludes at a lower potential than Li / Li ^+. Such materials include, for example, amorphous carbon (hard carbon), artificial graphite, natural graphite, graphite, thermally decomposed carbon, coke, glassy carbon, calcined body of organic polymer compound, mesocarbon microbeads, carbon fiber, and the like. In addition to carbon materials such as activated carbon, graphite, carbon colloid, and carbon black, metallic lithium, metal oxides, metal nitrides, lithium alloys, tin alloys, silicon alloys, intermetallic compounds, organic compounds, inorganic compounds, and metals. Examples thereof include complexes and organic polymer compounds.

The negative electrode active material may be used alone or in combination of two or more.

The number average particle size (primary particle size) of the negative electrode active material is preferably 0.1 μm to 100 μm, and more preferably 1 μm to 10 μm. The number average particle size of the negative electrode active material is measured in the same manner as the number average particle size of the positive electrode active material.

Examples of the conductive auxiliary agent include graphite, acetylene black, carbon black typified by Ketjen black, and carbon fiber. The number average particle size (primary particle size) of the conductive auxiliary agent is preferably 10 nm to 10 μm, and more preferably 20 nm to 1 μm. The number average particle size of the conductive auxiliary agent is measured in the same manner as the number average particle size of the positive electrode active material. The content ratio of the conductive auxiliary agent is preferably 20 parts by mass or less, and more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material.

Examples of the binder include PVDF, PTFE, polyacrylic acid, styrene-butadiene rubber, and fluororubber. The content ratio of the binder is preferably 10 parts by mass or less, more preferably 0.5 to 6 parts by mass, based on 100 parts by mass of the negative electrode active material.

The content ratio of the lithium ion conductor is preferably 25 parts by mass or less, and more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the negative electrode active material.

The negative electrode is obtained, for example, as follows. That is, first, a negative electrode mixture containing a negative electrode mixture is prepared by dispersing the negative electrode mixture obtained by adding a conductive auxiliary agent, a binder, a lithium ion conductor, or the like to the negative electrode active material and mixing them in a solvent. do. The solvent is not particularly limited, and conventionally known solvents may be used. For example, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, water and the like can be used. The solid content concentration in the negative electrode mixture-containing slurry is preferably 30 to 80% by mass, more preferably 40 to 70% by mass. Next, this negative electrode mixture-containing slurry is applied onto the negative electrode current collector and dried to form a negative electrode active material layer.

The negative electrode current collector is composed of, for example, a metal foil such as a copper foil, a nickel foil, or a stainless steel foil. The negative electrode current collector may have a carbon-coated surface or a mesh-shaped current collector. The thickness of the negative electrode current collector is preferably 5 to 40 μm, more preferably 6 to 35 μm, and even more preferably 7 to 30 μm.

The negative electrode mixture layer (negative electrode) is formed by compressing the negative electrode active material layer obtained after drying by a roll press or the like. The thickness of the negative electrode mixture after compression is preferably 10 to 300 μm, more preferably 20 to 280 μm, and even more preferably 30 to 250 μm.

<6. Lithium-ion conductor layer>
The non-aqueous secondary battery of the present embodiment preferably includes a lithium ion conductor layer between the positive electrode and the negative electrode from the viewpoint of preventing short circuits between the positive and negative electrodes and imparting safety such as shutdown. The lithium ion conductor layer may be composed of only the lithium ion conductor, may be mixed with the second lithium ion conductor, and may contain a separator which has been used in a conventional electrolytic solution. May be good.

The separator may be the same as that provided in a known non-aqueous secondary battery, and an insulating thin film having high ion permeability and excellent mechanical strength is preferable. Examples of the separator include woven fabrics, non-woven fabrics, and microporous membranes made of synthetic resin. Among these, microporous synthetic resin membranes are preferable.

As the synthetic resin microporous membrane, for example, a polyolefin-based microporous membrane such as a microporous membrane containing polyethylene or polypropylene as a main component or a microporous membrane containing both of these polyolefins is preferably used. .. As the non-woven fabric, for example, a porous film made of a heat-resistant resin such as ceramic, polyolefin, polyester, polyamide, liquid crystal polyester, or aramid is used.

The separator may be a single layer or a plurality of laminated microporous membranes of one type, or may be a laminate of two or more types of microporous membranes.

<7. Battery exterior ＞
The configuration of the battery exterior of the non-aqueous secondary battery in the present embodiment is not particularly limited, and for example, any battery exterior of a battery can and a laminated film exterior can be used. As the battery can, for example, a metal can made of steel or aluminum can be used. As the laminated film exterior body, for example, two laminated films having a three-layer structure of heat-melted resin / metal film / resin are stacked with the heat-melted resin side facing inward, and the end is sealed with a heat seal. Can be used.

When a laminated film exterior body is used, the positive electrode terminal (or the lead tab connected to the positive electrode terminal) and the negative electrode terminal (or the lead tab connected to the negative electrode terminal) are connected to the positive electrode current collector and the negative electrode current collector, respectively, and both terminals (or the lead tabs) are connected. The laminated film outer body may be sealed with the end portion of the lead tab) pulled out to the outside of the outer body.

<8. Battery manufacturing method>
The non-aqueous secondary battery of the present embodiment is characterized by comprising the above-mentioned polymer electrolyte.

The non-aqueous secondary battery of the present embodiment can be produced by a known method using, for example, the above-mentioned lithium ion conductor, positive electrode, negative electrode and, if necessary, a separator.

First, a laminate consisting of a positive electrode, a negative electrode, a lithium ion conductor, and, if necessary, a separator is formed.

for example:
A mode in which a positive electrode and a negative electrode are wound in a laminated state in which a lithium ion conductor and a separator are interposed between them to form a laminated body having a wound structure;
An embodiment in which the laminate is formed into a multilayer laminate in which a lithium ion conductor and a separator are interposed between a plurality of sets of positive electrodes and negative electrodes, respectively, by a treatment such as bending the laminate or laminating a plurality of the laminates;
Etc. are possible.

Next, the non-aqueous secondary battery according to the present embodiment can be produced by accommodating and sealing the above-mentioned laminate in the battery case (battery exterior).

The shape of the non-aqueous secondary battery of the present embodiment is not particularly limited, and for example, a cylindrical shape, an elliptical shape, a square cylinder shape, a button shape, a coin shape, a flat shape, a laminated shape and the like are preferably adopted.

The non-aqueous secondary battery of the present embodiment can function as a battery by the initial charging, but is stabilized by decomposing a part of the lithium ion conductor during the initial charging. The method of initial charging in the present embodiment is not particularly limited, but the initial charging is preferably performed at 0.001 to 0.3C, more preferably 0.002 to 0.25C, and 0.003. It is particularly preferable to carry out at ~ 0.2C. It is also preferable that the initial charging is performed through the constant voltage charging in the middle. The constant current that discharges the rated capacity in 1 hour is 1C. By setting a long voltage range in which the lithium salt is involved in the electrochemical reaction, SEI (Solid Electrolyte Interface) is formed on the electrode surface, which has the effect of suppressing an increase in internal resistance including the positive electrode. In addition to this, the reaction product is not firmly immobilized only on the negative electrode, and somehow gives a good effect to members other than the negative electrode, such as the positive electrode and the separator. Therefore, it is very effective to perform the initial charging in consideration of the electrochemical reaction of the lithium salt dissolved in the electrolytic solution.

The non-aqueous secondary battery of the present embodiment can also be used as a battery pack in which a plurality of non-aqueous secondary batteries are connected in series or in parallel. From the viewpoint of controlling the charge / discharge state of the battery pack, the working voltage range per battery pack is preferably 2 to 5 V, more preferably 2.5 to 5 V, and preferably 2.75 V to 5 V. Especially preferable.

Hereinafter, the present invention will be illustrated by examples, but these examples do not limit the present invention.

[Example 1]
Lithium bis (trifluoromethanesulfon) imide (LiTFSI, manufactured by Solvay) and 2-adamantanone (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were dry-blended to 3 mol / L and mixed with a ball mill. The mixed powder is filled on a stainless steel plate in a hole having a diameter of 5 mm in the center of a spacer having a thickness of 15 μm, pressed and molded, and then transferred onto a hot plate heated to 180 ° C. and melted. I let you. After further placing a stainless steel plate on it, the melt was rapidly cooled to 25 ° C. As a result, a SUS / (LiTFSI: 2-adamantanone) / SUS element was obtained. When the ionic conductivity of the device was measured at 25 ° C. by the AC impedance method, ^{a value of 2.1 × 10-5} S / cm was obtained.

[Example 2]
The cathode is a 50 μm composite film placed on a current collector made of aluminum coated with a carbon base layer, which composite is lithium iron phosphate (LFP) as the active material for the electrodes. , Carbon black as a material for producing electron conductivity, and 1 mol / L LiTFSI: polyethylene oxide (PEO) as a lithium ion conductor. The ion conductive layer sandwiched between the cathode and the anode is a dry blend of LiTFSI and 2-adamantanone so as to be 3 mol / L, mixed with a ball mill, and the mixed powder is on a film that has been subjected to a mold release treatment. A hole with a diameter of 5 mm in the center of a spacer with a thickness of 15 μm is filled, pressed and molded, and a heat-resistant film that has been subjected to a mold release treatment is further sandwiched, moved onto a hot plate heated to 180 ° C., and melted. After that, it was rapidly cooled to 20 ° C. An ion conductive layer with a spacer was placed on the above-mentioned cathode, and a Li foil having a thickness of 100 μm was further placed and pressed. As a result, a cathode / (LiTFSI: 2-adamantanone) / anode element was obtained. A battery containing this element was obtained. When 0.1C was charged and discharged using this, a value close to the theoretical capacity could be obtained.

Conventionally, a single material (for example, LiTFSI only, 2-adamantanone only) has a high melting point, for example, LiTFSI is 236 ° C., 2-adamantanone is 270 ° C., and 200 ° C. or higher for interface formation. Heating was required, and battery production and even film formation did not remain. However, in Examples 1 and 2, it is surprising that melting at 180 ° C. was confirmed, and it became possible to measure ionic conductivity and manufacture a lithium ion battery. It is believed that this could be achieved by using closed-shell hollow molecules with a specific molecular design. Since charge / discharge can be confirmed and the theoretical capacity is obtained, the solid state is maintained near room temperature while having sufficient fluidity during heating. It is clear that being able to form a very good interface at a low temperature of about 100 ° C., which is lower than before, has a great effect on processability.

Although the embodiment for carrying out the present invention has been described above, the present invention is not limited to the above embodiment. The present invention can be modified in various ways without departing from the gist thereof.

100 Non-aqueous secondary battery 110 Exterior body 120 One area of the exterior body (bulging space)
130 Aluminum tab 140 Nickel tab 150 Positive electrode 160 Negative electrode 170 Lithium ion conductor layer

Claims (6)

It contains at least one lithium salt and at least one closed-shell hollow molecule, and the number of elements constituting the closed-shell hollow molecule is 12 or more and 100 or less, and the molecular weight of the closed-shell hollow molecule is 100 or more and 1 Lithium having a lithium ion conductor of 000 or less, the closed-shell hollow molecule is a nonionic molecule, and the closed-shell hollow molecule is contained in an amount of 30% by mass or more based on 100% by mass of the lithium ion conductor. Ion conductor. The lithium ion conductor according to claim 1, wherein the closed-shell hollow molecule includes one body-centered substantially spherical portion and at least one peripheral outer substantially spherical convex portion or outer peripheral substantially spherical concave portion. The van der Waals image closest to the center of gravity in the atomic arrangement of the closed-shell hollow molecule found based on the crystal structure analysis and the body-centered spherical portion of the closed-shell hollow molecule drawn based on the van der Waals radius. 2. When the distance between the point and the center of gravity is S1 and the distance between the point of the Van der Waals drawing farthest from the center of gravity and the center of gravity is S2, S1 / S2 is 0.6 or more and 1.0 or less. The lithium ion conductor according to. The lithium salt is a lithium salt represented by Li ₂ B ₁₀ H _10-a X _a [in the formula, X is selected from F, Cl, Br, or I, and a is an integer of 0 to 10]. , LiB ₁₂ H _12-b Y _b [In the formula, Y is selected from F, Cl, Br, or I, and b is an integer from 0 to _{12 ], LiCB 11} H 12- _c Z _c [In the formula, Z is selected from F, Cl, Br, or I, and c is an integer from 0 to 12] LiCB ₉ H _10-d W _d [In the formula] , X is selected from F, Cl, Br, or I, and d is an integer from 0 to 10.] Lithium salt represented by LiN (SO ₂ F) ₂ , LiN (SO ₂ CF ₃ ) ₂ , The lithium ion conductor according to any one of claims 1 to 3, which is LiN (SO ₂ C ₂ F ₅ ) _{2 or a combination thereof.} At least one of the closed-shell hollow molecules selected from the group consisting of ortho-carborane, meta-carborane, para-carborane, 2-adamantanone, 1-adamantanone, 1-adamantanane carbonitrile, and 2-adamantanane carbonitrile. The lithium ion conductor according to any one of claims 1 to 3. A non-aqueous secondary battery comprising the lithium ion conductor according to any one of claims 1 to 5.

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