JP2682098B2 - Polymer solid electrolyte - Google Patents

Description

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

Conventional technology and its problems Gelled polyethers obtained by dissolving alkali metal salts, alkaline earth metal salts, etc. in high concentrations show relatively high ionic conductivity, and therefore are not suitable as solid electrolytes. Has a wide interest.

As an example in which a liquid polyether is gelled by cross-linking and used as a solid electrolyte material, there is disclosed in Japanese Patent Laid-Open No. 63-1354.
77, 63-76273, 62-249361, and the like. Japanese Unexamined Patent Publication (Kokai) No. 61-135477 proposes to use a crosslinked body of acroyl-modified polyalkylene oxide as a solid electrolyte material. This crosslinked product is
Since it is crosslinked by light, it has good productivity, but since it contains an ester bond in the structure of the crosslinked body, there is a problem in that the mechanical strength of the ester bond is degraded chemically or electrochemically, and the mechanical strength is reduced. JP-A-63-76273 proposes that an ester bond is formed by a reaction between a polyether and a diacrylate to cross-link the polyale. Cause a decrease in dynamic strength. Japanese Patent Application Laid-Open No. 62-249361 proposes that a urethane bond is formed by a reaction between a polyether and a diisocyanate to crosslink the polyether. The urethane bond is more thermally stable than the ester bond, but when used as an electrolyte of a battery, it causes decomposition and cleavage due to an electrochemical reaction, which causes a decrease in mechanical strength. Furthermore, the cross-linking method by the formation of ester bond and urethane bond is 2
Since it is a liquid mixing type method, the productivity is extremely low.

OBJECT OF THE INVENTION The present invention has been made in view of the above problems, and provides a polymer solid electrolyte having high chemical conductivity or electrochemical stability, excellent productivity, and high ion conductivity. The purpose is.

In order to achieve the above object, the present invention provides one or more polyethers having at least one hydroxyl group and having a polyethylene oxide structure, a polypropylene oxide structure, or a copolymer structure of ethylene oxide and propylene oxide. The hydrogen of the hydroxyl group is represented by the following general formula [I] or [II] The cross-linked polyether obtained by reacting a polyether having a reactive double bond substituted with is an alkali metal salt,
It is a solid polymer electrolyte characterized by containing one or more salts selected from alkaline earth metal salts and organic ammonium salts.

The copolymer structure of ethylene oxide and propylene oxide may be a block copolymer structure or a random copolymer structure. In particular, a random copolymer structure is advantageous because it exhibits high ionic conductivity at low temperatures. The ratio of ethylene oxide units to propylene oxide units is not particularly limited, but when the ratio of ethylene oxide units is 70% or more in terms of molar ratio, a solid electrolyte exhibiting high ionic conductivity can be obtained.

A polyether having a reactive double bond is at least 1
It is obtained by reacting a polyether having one or more hydroxyl groups with a halide of a group having a reactive double bond under basic conditions. As the halogen of the halide, Cl, Br, I is generally used. The group having a reactive double bond is an allyl group, a cinnamyl group, a crotyl group or a methallyl group.
This reaction method is well known as the Williamson synthesis method.

As the alkali metal salt, alkaline earth metal salt, or organic ammonium salt contained in the polyether crosslinked product,
LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiPE ₆ , LiI, LiBr, LiSCN,
NaI, NaBr, NaSCN, KSCN, MgCl ₂ , Mg (ClO ₄ ) ₂ , (CH ₃ ) ₄ NB
F ₄ , (CH 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 NClO ₄ ,, (n-C ₄ H ₉ ) ₄ NI, (n
-C ₅ H ₁₁ ) ₄ NI is preferable, but not limited thereto.

The method for reacting the polyether having a reactive double bond may be any of heating, irradiation with ultraviolet rays and / or visible light, and irradiation with electron beams. In the case of the heating method, the reaction can be easily caused by adding benzoyl peroxide, azobisisobutyronitrile or the like as a radical reaction initiator. Further, in the case of the method of irradiating with ultraviolet light and / or visible light, the reaction can be easily caused by adding benzoin, benzophenone, acetophenone, α-phenylacetophenone or the like as a photoinitiator.

Examples Hereinafter, details of the present invention will be described with reference to examples.

Example 1. 1 part by weight of lithium perchlorate and 0.1 part by weight of benzoyl peroxide were uniformly mixed and dissolved in 10 parts by weight of allyl etherified polyethylene oxide (allyl etherification rate 98%, average molecular weight 3000). This mixture was cast on a glass plate and reacted at 90 ° C. for 1 hour in an argon stream to obtain a 200 μm film. The ionic conductivity of this membrane was measured by the complex impedance method.
It was 3.0 × 10 ^-5 Scm ^-2 . The mechanical strength was 15.2 kg cm ^{-2 in} tensile strength. This film was energized at 80 ° C. in an Ar stream at a current density of 10 μAcm ⁻¹ for 1000 hours. The strength of the film after electrification was 13.2 kg cm ^-2, and there was no practical problem.

Example 2. 1 part by weight of lithium perchlorate and 0.01 part by weight of benzophenone were uniformly mixed and dissolved in allyl etherified polyethylene oxide (allyl etherification rate 96%, average molecular weight 3000). Cast this mixture on a glass plate,
4 from a distance of 15 cm with a 1 KW UV lamp in an argon stream
It was irradiated for a minute to obtain a 100 μm film. The ionic conductivity of this membrane was measured by the complex impedance method.
It was 3.0 × 10 ^-5 Scm ^-2 at ℃. The mechanical strength was 15.2 kg cm ^{-2 in} tensile strength. Example using this membrane
The same energization as in 1. was performed. The strength of the membrane after energization is 13.2 kg c
It showed m ^-2 and had no practical problems.

Example 3. The molar ratio of ethylene oxide and propylene oxide is
A cinnamyl etherified polyether having a random copolymer structure of 8: 2 (cinnamyl etherification rate 98
%, Average molecular weight 3300), 1 part by weight of lithium perchlorate and 0.01 parts by weight of benzophenone were uniformly mixed and dissolved. This mixture was cast on a glass plate and irradiated with a 1 KW ultraviolet lamp at a distance of 15 cm for 4 minutes in an argon stream to obtain a 100 μm film. The ionic conductivity of this film was measured by the complex impedance method and found to be 5.0 at 25 ° C.
It was × 10 ^-5 Scm ^-2 . Mechanical strength is 1 in tensile strength
It showed 5.4 kg cm ^-2 . Using this film, the same electricity as in Example 1 was applied. The strength of the film after electrification was 13.0 km cm ^-2, and there was no problem in practical use.

Example 4. The molar ratio of ethylene oxide and propylene oxide is
It has a random copolymer structure of 8: 2. Cinnamyl etherified polyether (Cinnamyl etherification rate 98
%, Average molecular weight 3300), 1 part by weight of lithium perchlorate was uniformly mixed and dissolved. This mixture was cast on a glass plate and irradiated with an electron beam in an argon stream at an accelerating voltage of 300 KeV, an electron beam current of 10 mA, and an electron dose of 3.0 MGr to obtain 100 μm.
m was obtained. The conductivity of ions in this film was measured by the complex impedance method and found to be 5.0 × 10 ^-5 Scm at 25 ° C.
It was ^-2 . Mechanical strength is 15.4 kg cm in tensile strength
Showed ^-2 . Using this film, the same electricity as in Example 1 was applied. The strength of the film after electrification was 13.1 kg cm ^-2, and there was no problem in practical use.

Effects of the Invention As described above, the present invention can provide a polymer solid electrolyte having excellent chemical or electrochemical stability, excellent productivity, and high ion conductivity. The value is extremely large.

Claims (4)

(57) [Claims] 1. A polyether having at least one hydroxyl group and having a polyethylene oxide structure, a polypropylene oxide structure, or a copolymer structure of ethylene oxide and propylene oxide, wherein two or more hydrogen atoms of the hydroxyl groups are replaced by the following general formula: I] or [II] The cross-linked polyether obtained by reacting a polyether having a reactive double bond substituted with is an alkali metal salt,
1. A polymer solid electrolyte comprising at least one salt selected from alkaline earth metal salts and organic ammonium salts. 2. The polymer solid electrolyte according to claim 1, wherein the copolymer structure of ethylene oxide and propylene oxide is a random copolymer structure. 3. The solid polymer electrolyte according to claim 1, wherein the polyether having a reactive double bond is crosslinked by irradiation with ultraviolet rays and / or visible rays. 4. The solid polymer electrolyte according to claim 1, wherein the polyether having a reactive double bond is crosslinked by irradiation with an electron beam.