JP2586667B2 - Polymer solid electrolyte - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a solid polymer electrolyte used for primary batteries, secondary batteries, electrochromic displays, electrochemical sensors, iontophoresis, capacitors and other electrochemical devices. is there.

Prior art and its problems Conventional polymer solid electrolytes have mainly been a crosslinked network of polyether having a molecular weight lower than 2,000. In particular, those obtained by crosslinking a polyether modified with a diacrylate or dimethacrylate have a drawback of low flexibility. Therefore, when used in a battery or the like, it is easily broken by an external force, causing a short circuit or the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and has as its object to provide a polymer solid electrolyte having excellent mechanical strength and high ionic conductivity.

In order to achieve the above object, the present invention provides a mixture of a diacrylate or / and a dimethacrylate of polyethylene glycol and a monoacrylate or / and / or a monomethacrylate of a copolymer of ethylene oxide and propylene oxide. Is a polymer solid electrolyte containing an ionic salt, and the polyethylene glycol has a molecular weight of 2,000 to 30,000.

Further, the above-mentioned polymer solid electrolyte contains a compound capable of dissolving the ionic salt together with the ionic salt.

Also, the formation of the crosslinked network is the above-mentioned polymer solid electrolyte by irradiation of thermal, actinic rays or ionizing radiation.

Examples Hereinafter, the present invention will be described in detail with reference to examples.

Example 1 A liquid obtained by mixing 50 parts by weight of a diacrylate of polyethylene glycol (molecular weight: 4,000) and 50 parts by weight of a monoacrylate of methoxylated diethylene glycol was added to a liquid.
LiCF ₃ SO ₃ 11.5% by weight propylene carbonate solution was added to 10
0 parts by weight were added and mixed uniformly. This liquid was cast on a glass plate and irradiated with 6 Mrad of electron beam.

The thickness of this film was 100 μm, and the ionic conductivity measured by the complex impedance method was 3 × 10 ⁻⁴ Scm ⁻¹ (25 ° C.). This film did not crack even when subjected to a 180 ° bending test as a flexibility test.

Table 1 summarizes the performance of polyethylene glycol diacrylates having molecular weights of 400, 1,000, 2,000 and 10,000.

Example 2 A mixture of 50 parts by weight of a diacrylate of polyethylene glycol (molecular weight: 4,000) and 50 parts by weight of a monoacrylate of methoxylated diethylene glycol was added to
100 parts by weight of a dimethoxyethane solution of 11.5% by weight of LiOF ₃ SO _{3 was} added and mixed uniformly. This liquid was cast on a glass plate to evaporate dimethoxyethane. Then 6Mra
The electron beam of d was irradiated.

The thickness of this film was 100 μm, and the ionic conductivity measured by the complex impedance method was 7 × 10 ⁻⁶ Scm ⁻¹ (25 ° C.). No cracking occurred in the 180 ° bending test. Table 2 also shows the results of investigations of polyethylene glycol diacrylates having molecular weights of 400, 1,000, 2,000 and 10,000.

Example 3 Instead of electron beam irradiation in Example 2, 5 parts by weight of azoisobutyronitrile was added and reacted at 80 ° C. for 1 hour. Except for this, all were the same as Example 2.

The membrane obtained here had a thickness of 100 μm and an ionic conductivity of 7 × 10 ⁻⁶ Scm ⁻¹ (25 ° C.). No cracking occurred in the 180 ° bending test. At this time, the molecular weight of the diacrylate of polyethylene glycol was 4,000.

Example 4 In Example 2, instead of electron beam irradiation, 2 parts by weight of benzophenone and 2 parts by weight of triethylamine were added, and ultraviolet rays were irradiated from a distance of 15 cm for 30 seconds with a 1 kW mercury lamp. All other conditions were the same as in Example 2.

In the film obtained here, the molecular weight of the diacrylate of polyethylene glycol was 4,000, and the thickness of the film was 1
00 μm, ionic conductivity was 7 × 10 ⁻⁶ Scm ⁻¹ (25 ° C.), and no crack occurred in the test between 180 ° folding.

Example 5 In Example 1, a dimethacrylic acid ester of polyethylene glycol (molecular weight: 4,000) was used in place of the diacrylic acid ester of polyethylene glycol. All other conditions were the same. The resulting film has a thickness of 100μ
m, ionic conductivity is 5 × 10 ⁻⁴ Scm ⁻¹ (25 ° C.), 180
割 れ No cracks occurred in the bending test.

Example 6 A liquid obtained by mixing 50 parts by weight of a polyethylene glycol dimethacrylate (molecular weight: 4,000) and 50 parts by weight of a monomethoxylated copolymer of ethylene oxide and propylene oxide (containing 20 mol% of propylene oxide and a molecular weight of 400) 100 parts by weight of a propylene carbonate solution of 11.5% by weight of LiCF ₃ SO _{3 was} added and uniformly mixed. This liquid was cast on a glass plate and irradiated with 6 Mrad of electron beam.
The thickness of this film is 100 μm and the ionic conductivity is 6 × 10 ^-4 Scm ^-1
(25 ° C.). No cracking occurred in the 180 ° bending test.

In addition, the polymer solid electrolyte contains a compound (solvent) that is compatible with the ionic salt. If necessary,
By including a solvent in the solid electrolyte, ionic conductivity can be increased. In this case, when the molecular weight of the polyether is high, a large amount of a solvent can be contained, the ion conductivity is also improved, and the strength of the crosslinked network polymer swollen by the solvent can be improved.

As the ionic _{salt, LiClO 4, LiBF 4, LiA} S F 6, LiCF
₃ SO ₃ , LiPF ₆ , LiI, LiBr, LiSCN, NaI, Li ₂ B ₁₀ Cl ₁₀ , LiCF ₃ CO ₂ ,
NaBr, NaSCN, KSCN, MgCl ₂ , Mg (ClO ₄ ) ₂ , (CH ₃ ) ₄ NBF ₄ , (C
H ₃ ) ₄ NBr, (C ₂ H ₅ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ NI, (C ₃ H ₇ ) ₄ NBr,
_{(N-C 4 H 9)} 4 NI, (n-C 5 H 11) 4 NI are preferred but not limiting.

Compounds that can dissolve ionic salts include tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-
Dioxolane, 4,4-dimethyl-1,3-dioxolane, γ
-Butyrolactone, ethylene carbonate, propylene carbonate, butylene carbonate, sulfolane, 3
-Methyl sulfolane, tert.-butyl ether, iso-butyl ether, 1,2-dimethoxyethane, 1,2-ethoxymethoxyethane, methyldiglyme, methyltriglyme, methyltetraglyme, ethylglyme, ethyldiglyme, etc. No limitation.

By increasing the molecular weight of polyethylene glycol, flexibility and strength can be further increased. However, if the molecular weight is excessively increased, the reaction rate is decreased, and the productivity is deteriorated, and the crystallization is liable to occur. Therefore, the molecular weight is preferably 2,000 to 30,000.

Effect of the Invention As described above, the present invention can provide a polymer solid electrolyte having excellent mechanical strength and high ionic conductivity, and therefore has an extremely large industrial value.

Claims (3)

(57) [Claims] 1. A crosslinked network structure by reacting a mixture of a diacrylate and / or dimethacrylate of polyethylene glycol and a monoacrylate and / or monomethacrylate of a copolymer of ethylene oxide and propylene oxide. The polymer obtained is a polymer solid electrolyte containing an ionic salt, wherein the polyethylene glycol has a molecular weight of 2,000 to 30,000. 2. The polymer solid electrolyte according to claim 1, further comprising a compound capable of dissolving the ionic salt together with the ionic salt. 3. The polymer solid electrolyte according to claim 1, wherein the crosslinked network is formed by irradiation with thermal, actinic rays or ionizing radiation.