JPH08884B2 - Solid electrolyte composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solid electrolyte composition used in electrochemical devices such as batteries, capacitors, sensors, display devices and recording devices.

2. Description of the Related Art By using a solid electrolyte, it is possible to obtain a solid electrochemical device such as a small and thin battery and an electric double layer capacitor without liquid leakage.

However, since the element is made of a solid material lacking elasticity, it has a drawback that it is extremely fragile against mechanical impact and easily damaged.

In order to solve such a problem, as described in JP-A-63-245871, the flexibility is imparted by compounding a plastic resin with an ion-conductive inorganic compound, and it is also provided with respect to mechanical impact. Attempts have been made to make solid electrolytes that are less likely to break, and polymer solid electrolytes composed of polyethylene oxide (PEO) and alkali metal salts have been proposed. (“Fast Ion Transport
in Solid "P.Vanishstaet.al., Eds.P.131 (1979) North
Holand Publishing Co.).

However, many ion-conductive inorganic compounds lack chemical stability such as moisture resistance, and particularly alkali metal ion conductors have poor chemical stability. It is difficult to handle in many cases because unreacted groups such as active hydrogen in the plastic resin or minute amount of moisture and oxygen in the atmosphere cause deterioration in the manufacturing process when compounding with.

Compared with inorganic solid electrolytes, polymer solid electrolytes are characterized by being lighter in weight, excellent in flexibility, and chemically stable, but compared to general plastic resins, it is often difficult to form a homogeneous film, Further, there is a drawback that the ionic conductivity is lowered when trying to improve the homogeneity / formability (film forming ability).

Means for Solving the Problems As a result of repeated studies for the purpose of obtaining a solid electrolyte composition having excellent ion conductivity and good moldability, the present invention has been achieved by the solid electrolyte of the present invention. Is a polyether compound obtained by adding ethylene oxide (EO) and / or propylene oxide (PO) to a polyamine compound, an ion-exchange layered compound, and an ionic substance represented by the formula MX (where M is It is a composition containing at least a metal ion, a proton, and an ammonium ion that move in the solid electrolyte composition by the action of an electric field, and X is an anion of a strong acid.

Action In the solid electrolyte composition thus obtained, the ionic compound MX forms a complex with the polyether compound and the ion-exchangeable layered compound, and is formed on the interlayer or surface of the crystal of the layered compound. A high-concentration pathway is formed which is advantageous for ionic conduction. In producing the solid electrolyte,
The polyether compound facilitates the mixing of the solvent and the ion-exchangeable layered compound and promotes the formation of a uniform ion-conducting path, and further prevents the aggregation of the ion-conducting powder during the addition and mixing of the solvent, and the solvent. And a layered compound having an ion exchange property can be uniformly mixed and dispersed. In this way, high ionic conductivity and homogeneity are developed. Further, the ethylene oxide chain or propylene oxide chain of the polyether compound and the microporous structure of the ion-exchangeable layered compound are entangled with each other to impart good moldability and sufficient mechanical strength.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.
In the following examples, parts,% and ratios are parts by weight,% by weight and ratios by weight, unless otherwise specified.

A polyether compound obtained by adding ethylene oxide and / or propylene oxide to a polyamine compound is a polyamine compound which is 100
-180 ° C, 1-10 atm ethylene oxide or
And propylene oxide can be obtained by addition reaction. As the polyamine compound, polyethyleneimine, polyalkylenepolyamine or derivatives thereof can be used.

Examples of the polyalkylene polyamine include diethylene triamine, triethylene tetramine, hexamethylene tetramine, dipropylene triamine and the like.

The number of moles of ethylene oxide and propylene oxide added is 2 to 500 moles per active hydrogen atom of the polyamine compound. The ratio of ethylene oxide (EO) and propylene oxide (PO) added is 80/20 to 10/90 (= EO / P
O). The polyether thus obtained has an average molecular weight of 10 to 5,000,000.

The ionic substance MX is not particularly limited, but LiI, Li
ClO ₄ ,, LiCF ₃ SO ₃ ,, LiPF ₆ ,, LiBF ₄ ,, LiSCN, LiAsF ₆ ,, NaI, NaSCN, N
Soluble salts such as aBr, KI, AgNO ₃ , CuCl ₂ , Mg (ClO ₄ ) ₂ and AlCl ₃ are used.

In particular, when MX is a monovalent alkali metal salt, the alkali metal ion is chemically stabilized by forming a complex with the polyether and the ion-exchangeable layered compound, so that alkali metal ion conduction It has the advantage that it is easier to handle than inorganic inorganic compounds.

Examples of ion-exchangeable layered compounds include montmorillonite, hectorite, saponite, clay minerals containing silicates such as smectite, zirconium phosphate, phosphates such as titanium phosphate, vanadic acid, antimony acid, tungstic acid, or And those modified with an organic cation such as a quaternary ammonium salt or an organic polar compound such as ethylene oxide or propylene oxide.

Furthermore, an ion conductive powder can be added and mixed into the solid electrolyte of the present invention as long as the chemical stability is not impaired. Such ion conductive powder for _{example, MeCu 4 I 2-x Cl} 3 + x (x = 0.25-1.0, Me, Rb, K, NH 4 or mixtures of them) and CuI-Cu ₂ O − Copper ion conductive solid electrolyte such as MoO ₃ glass, RbAg ₄ I ₅ , Ag ₃ Si, AgI
-Ag ₂ O-MoO ₃ glass, silver ion conductive solid electrolyte such as Ag ₆ I ₄ WO ₄ , LiI, LiI.H ₂ O, Li-β-Al ₂ O ₃ , LiI-Li ₂ S-B
₂ S ₃ etc. lithium ion conductive solid electrolyte, H ₃ Mo ₁₂ PO ₄₀
A proton-conducting solid electrolyte such as 29H ₂ O, H ₃ W ₁₂ PO ₄₀ , 29H ₂ O can be used. Any of ultrafine particles having an average particle size of 1 μm or less to particles having an average particle size of several tens of μm can be used. The addition amount of the ion conductive powder is not limited as long as the moldability of the solid electrolyte is not impaired.

The solid electrolyte composition of the present invention is obtained as follows.
Ion-exchangeable layered compound powder was added to a solvent in which 1 to 50% of an ionic compound was dissolved so as to be 1 to 50%, and then
A polyether compound having an EO chain and / or a PO chain is added so as to have a ratio of 0.1 to 20% with respect to the entire slurry, and pulverized and mixed by a mixing pulverizer such as a disperser to obtain a solid content of 5 to 95%. Prepare an electrolyte slurry. Next, the slurry thus obtained is molded as it is, or after being cast or coated on a support such as a Teflon plate or a nylon mesh sheet to be molded, the solvent is partially or wholly dispersed to form a solid. An electrolyte composition is obtained. If the support is a mesh, it can be used as a solid electrolyte composition with the support integrated.

If necessary, these steps are performed in a dry atmosphere having a relative humidity of 40% or less.

As the solvent, ketone-based solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, saturated hydrocarbon solvents such as n-hexane, n-heptane, n-octane and cyclohexane, aromatic solvents such as benzene, toluene and xylene. Solvents, ester solvents such as ethyl acetate, butyl acetate, propylene carbonate, alcohol solvents such as methanol, ethanol, isopropyl alcohol, ethylene glycol, glycerin, polyethylene glycol, nitriles such as acetonitrile, or water are used.

Example 1 An average obtained by adding ethylene oxide (EO) and propylene oxide (PO) to polyethyleneimine containing 10 N atoms in the molecule so that the ratio of EO and PO is 30/70. A polyether compound having a molecular weight of 180,000 was dissolved in acetonitrile to prepare a 20% polyether solution (A). Further, γ-zirconium phosphate powder having an average particle size of 25 μm was added to a polyether solution (A) in which 10% LiCF ₃ SO ₃ was dissolved as an ionic substance so that the solid content was 30%. The mixture was stirred at 24 ° C. for 24 hours. The obtained electrolyte slurry was applied on a smooth Teflon plate using a doctor blade, and then applied in a dry argon stream at 130 ° C for 1
80 hours by drying for 5 hours and vacuum drying for 5 hours
A sheet-like solid electrolyte molded body (A1) having a conductivity of x80 mm and a thickness of 20 μm and having a lithium ion conductivity was obtained.

<Example 2> A polyether compound having an average molecular weight of 65000 obtained by adding EO to triethylenetetramine was dissolved in propylene carbonate to prepare a 10% polyether solution (B). Furthermore, montmorillonite powder with an average particle size of 15 μm was added to a polyether solution (B) in which 10% LiClO ₄ was dissolved as an ionic substance so that the solid content was 20%, and the mixture was stirred at 40 ° C for 24 hours. Mixed. The resulting electrolyte slurry was applied to a 330 mesh polyester mesh with a thickness of 85 μm and an aperture ratio of 40% on a smooth Teflon plate, dried in a dry argon stream at 130 ° C. for 1 hour, and then vacuumed for another 5 hours. By drying, size 80x80mm, thickness 115
A sheet-shaped lithium ion conductive solid electrolyte molded body (B1) having a thickness of μm was obtained.

<Example 3> A 10% polyether solution was prepared by dissolving a polyether compound having an average molecular weight of 15000 obtained by adding EO and PO at a ratio of EO / PO = 40/60 to hexamethylenetetramine in ion-exchanged water. (C) was adjusted. Furthermore, as an ionic substance
To a polyether solution (C) in which 20% LiClO ₄ was dissolved, γ-zirconium phosphate powder having an average particle size of 25 μm was added so that the solid content was 20%, and the mixture was stirred and mixed at 40 ° C. for 24 hours. . The obtained electrolyte slurry was applied on a silicone resin plate with a thickness of 85 μm, an aperture ratio of 40%, and a 330 mesh polyester mesh, and then dried at 80 ° C. for 1 hour and left in the air for a whole day and night. A sheet-shaped solid electrolyte molded body (C1) having a size of 80 × 80 mm and a thickness of 100 μm was obtained. This molded body (C
In 1), protons as well as lithium ions seem to act as conducting ions.

<Example 4> A polyether compound having an average molecular weight of 240,000 obtained by adding PO to dipropylenetetramine was dissolved in ion-exchanged water to prepare a 10% polyether solution (D). Furthermore, montmorillonite powder having an average particle size of 15 μm was added to a polyether solution (D) in which 20% of AlCl ₃ was dissolved as an ionic substance so that the solid content was 20%, and the temperature was 40 ° C.
Mix for 24 hours. The obtained electrolyte slurry was applied on a silicone resin plate with a thickness of 85 μm, an aperture ratio of 40%, and a polyester mesh of 330 mesh, and then at 80 ° C. for 1 hour.
80x80m after being dried for an hour and left in the air for 24 hours
A sheet-shaped solid electrolyte molded body (D1) having an m and a thickness of 105 μm was obtained. It seems that aluminum ions and protons act as conductive ions in this molded body.

<Example 5> Example 1 with an average particle diameter of 5μm as an inorganic solid electrolyte as the electrolyte slurry obtained in the same manner as Li-β-Al ₂ O ₃ powder of 20 wt% added to the electrolyte slurry (E) Obtained. After applying this on a smooth Teflon plate using a doctor blade, it was dried in a dry argon stream at 80 ° C for 1 hour and then vacuum dried for 5 hours to obtain a size of 80x80mm,
A sheet-like solid electrolyte molded body (E1) having a thickness of 35 μm and having lithium ion conductivity was obtained.

 Next, the conductivity of the solid electrolyte compact will be described.

The diameter of the solid electrolyte molded body obtained in each of Examples 1 to 5 was 10 mm.
Punched 10 discs each, sandwiched by 2 platinum discs, pressurized from the top and bottom with a pressure of 50 kg / cm ² , and apply an AC signal with an amplitude of 100 mV and a frequency of 10 KHz in an argon gas atmosphere. The alternating-current resistance value at 20 ° C. of the solid electrolyte molded discs added between the plates was measured. The average value of the obtained electric conductivity is shown in the table.

Effects of the Invention As described above, according to the present invention, it is possible to obtain a uniform solid electrolyte having excellent ionic conductivity. Such a solid electrolyte is used as an electrolyte for a solid-state lithium battery having a negative electrode such as lithium metal, a lithium alloy or a lithium compound, or a solid-state primary or secondary battery having a negative electrode such as zinc, aluminum or a hydrogen storage alloy. It can be used effectively.

Claims (2)

[Claims] 1. A polyether compound obtained by adding at least ethylene oxide or propylene oxide to a polyamine compound, an ion-exchangeable layered compound, and an ionic substance represented by the formula MX (where M is an electric field). A solid electrolyte composition containing at least a metal ion, a proton, and an ammonium ion which move in the solid electrolyte composition by the action, and X is an anion of a strong acid. 2. The solid electrolyte composition according to claim 1, wherein MX is an alkali metal salt.