JPH11306856A - Polymer solid electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an amorphous solid electrolyte with high ion conductivity and small temperature dependency that is suitable for a battery through blending, to a polysiloxane-polyether random copolymer, an electrolytic salt compound soluble thereto. SOLUTION: This polymer solid electrolyte is formed of a polysiloxane- polyether copolymer, which is a solid random copolymer having a main chain structure consisting of a structural unit of formula I and a structural unit of formula II, wherein X<1> and X<2> of formula I represent a substituent containing a cyclic carbonate, and an electrolytic salt compound soluble to this copolymer. This polymer solid electrolyte is used as a battery for electronic equipment. The polysiloxane-polyether copolymer suitably consists of 5-40 mol.% of the structural unit of formula I and 95-60 mol.% of the structural unit of formula II, and preferably 10-30 mol.% of the structural unit of formula I and 90-70 mol.% of the structural unit of formula II. The solid electrolyte has high ion conductivity even at low temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid polymer electrolyte, and more particularly, to a solid polymer electrolyte which has high ionic conductivity and low temperature dependency and can be used for batteries and the like. is there.

[0002]

2. Description of the Related Art In order to use a polymer solid electrolyte in a lithium ion battery or an electrochemical device, it must have high ionic conductivity in a wide temperature range from low to high and exhibit no crystallinity. Is essential. However, a solid polymer electrolyte that satisfies such required performance comprehensively has not been developed so far. For example, conventionally, organic solvents such as propylene carbonate and ethyl methyl carbonate have been widely used, but generally 70 to 90 ° C. is a limit of use in a high temperature range due to a relationship between a boiling point and a vapor pressure. Recently, as a method for improving the safety of such an organic solvent, research on a polymer solid electrolyte centered on polyethylene oxide (hereinafter referred to as PEO) has been conducted. PEO is a metal salt belonging to Group 1 or 2 of the periodic table, for example, LiCF ₃ SO ₂ , LiCl
It forms a complex with O ₄ , NaCF ₃ SO ₂ , LiI, etc., exhibits relatively good ionic conductivity in a temperature range of room temperature or higher, and has good storage stability. However, P
The ionic conductivity of EO has a large temperature dependence, and shows good ionic conductivity at 60 ° C or higher, but significantly lowers at a temperature of 20 ° C or lower. Therefore, it has been difficult to incorporate it into general-purpose products used at low temperatures. As a method for improving ionic conductivity by using low molecular weight PEO, low molecular weight PEO is added to the side chain of a vinyl polymer.
Is introduced by D. J. Banistar et al., Polymer, 25 , 1600 (1984). However, although this polymer material forms a complex with the Li salt, the ionic conductivity at a low temperature is insufficient. Furthermore, low molecular weight P is added to the side chain of polysiloxane.
EO introduced material is Journal of Pow
er Source, 20 , 327 (1987), JP-A-63-136409, and JP-A-2-265927, but the ionic conductivity at low temperatures is insufficient or not amorphous. It has not been put to practical use because it is not available.

[0003]

SUMMARY OF THE INVENTION The present invention provides an amorphous solid polymer electrolyte having high ionic conductivity even at a low temperature.

[0004]

Means for Solving the Problems The present inventors have made a polysiloxane-polyether random copolymer containing, as a copolymer component, a siloxane structural unit having two substituents containing a cyclic carbonate on each silicon and ethylene oxide. By blending a soluble electrolyte salt compound with the polymer,
It has been found that a solid polymer electrolyte having significantly increased ionic conductivity can be obtained. That is, the present invention
(1) a solid random copolymer having a main chain structure comprising a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2):
X ¹ and X ^{2 in the} formulas each comprise a copolymer of a polysiloxane and a polyether which is a substituent containing a cyclic carbonate, and a polymer solid electrolyte characterized by comprising an electrolyte salt compound soluble in the copolymer. This is a battery using.
As the polysiloxane-polyether copolymer used in the present invention, those having 5 to 40% of the structural unit of the formula (1) and 95 to 60% of the structural unit of the formula (2) are suitable. 10 to 30% of the structural unit of the formula (2) and 90 to 70% of the structural unit of the formula (2), more preferably 15 to 30% of the structural unit of the formula (1) and 85 to 70% of the structural unit of the formula (2) Is used. If the molar ratio of the formula (2) exceeds 95 mol%, an increase in the glass transition point and crystallization are observed, and the ionic conductivity of the solid polymer electrolyte is significantly reduced. On the other hand, if the molar ratio of the formula (2) is less than 70 mol%, the softening temperature of the copolymer decreases, and it becomes difficult to obtain a solid electrolyte at room temperature. However, in the present invention, X ¹ and X ² in the formula (1) are substituents containing a cyclic ether.
The siloxane structural unit represented by the formula is preferably a general formula

[0005]

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[0006] or

[0007]

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Is a siloxane structural unit represented by
In the formula, A ¹ , A ² , A ³ , and A ^{4 each} represent a substituted or unsubstituted alkyl group, aryl group, or oxyalkylene group, and n represents an integer of 1 or more. Examples of the compound of the siloxane structural unit in the present invention are shown below, but the present invention is not limited to these examples. In the compounds 1 to 6, n represents an integer of 1 or more. (Compound Example 1)

[0009]

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(Compound Example 2)

[0011]

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(Compound Example 3)

[0013]

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(Compound Example 4)

[0015]

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(Compound Example 5)

[0017]

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(Compound Example 6)

[0019]

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The electrolyte salt compound used in the present invention is not particularly limited as long as it is soluble in the polysiloxane-polyether copolymer of the present invention, but the following compounds are preferably used in the present invention. . That is, metal cations, ammonium ions, amidinium ions, and cations selected from guanidinium ions, chloride ions, bromide ions, element ions, perchlorate ions, thiocyanate ions, tetirafluoroboronate ions, nitrate ^{_{ion, AsF 6 -, PF 6 -}} , stearyl sulfonate ion, octylsulfonate ion, dodecylbenzenesulfonate ion, naphthalenesulfonate ion, dodecyl naphthalenesulfonate ion, R ¹ SO _{3
^{-, (R 1 SO 2)}} (R 2 SO 2) N -, and (R ¹ SO ₂₎
And an anion selected from (R ² SO ₂ ) (R ³ SO ₂ ) C ⁻ . Where R ¹ , R ² , R ³
Is an electron-withdrawing group. Preferably, R ¹ , R ² and R ³ are each independently a perfluoroalkyl group or a perfluoroaryl group having 1 to 6 carbon atoms. R ¹ , R ² ,
And R ³ may be the same or different. A transition metal cation can be used as the metal cation. Preferably, a cation of a metal belonging to Group 1 or 2 of the periodic table is used. Mn, Fe, C
It is also preferable to use a cation of a metal selected from o, Ni, Cu, Zn and Ag metals. One of the above compounds can be used as an electrolyte salt compound or a mixture of two or more thereof. In the present invention, the amount of the soluble electrolyte salt compound used is such that the mixing ratio of the polysiloxane and the polyether copolymer is 0 in the value of the number of moles of the electrolyte salt compound / the total number of oxygen atoms contained in the copolymer. .00
01 to 3, preferably 0.0005 to 0.3.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for producing a solid polymer electrolyte according to the present invention is not particularly limited, but usually, the respective components are mixed mechanically or dissolved in a solvent and mixed, and then the solvent is removed. It is manufactured by such a method. In the present invention, the type of the reaction vessel is not important. However, in order to prevent side reactions, the reaction is preferably performed in a reaction vessel formed of a non-reactive material. The method of the present invention can be carried out in a batch, semi-batch or continuous mode. This reaction vessel
For example, it may be a continuous stirred tank reaction vessel. This method is preferably performed in a batch system or a continuous system. The polymer compound of the present invention is synthesized, for example, as described below, but is not limited to this method. The solid random copolymer in which the main chain structure of the present invention comprises the structural unit represented by the above formula (1) and the structural unit represented by the formula (2) is obtained by dissolving an alkylene glycol and an amine compound in a solvent. General formula at room temperature under inert gas atmosphere

[0022]

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(Wherein X ¹ and X ² are substituents containing a cyclic carbonate group and may be the same or different), obtained by adding a solution obtained by diluting a dichlorosilane derivative represented by the formula Can be The amine compound used here is not particularly limited, and examples thereof include pyridine. The solvent is not particularly limited, and examples thereof include toluene. General formula

[0024]

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(Wherein X ¹ and X ² are substituents having a cyclic carbonate and may be the same or different), for example, is produced by the following method. It is obtained by contacting a compound containing dichlorosilane (H ₂ SiCl ₂ ) and a cyclic ether group and having a double bond at a terminal with a platinum compound catalyst or a rhodium compound catalyst, which is a hydrosilylation reaction catalyst, to perform an addition reaction. . As another method for synthesizing this kind of dichlorosilane, for example, tetrachlorosilane (Si
There is a method obtained by reacting a corresponding Grignard reactant with Cl ₄ ). A solution obtained by dissolving the dichlorosilane compound obtained above in a solvent is reacted dropwise with a solution obtained by dissolving an alkylene glycol and an amine compound in a solvent.The reaction temperature at that time is particularly limited. Although not limited, the reaction is preferably performed in the range of 0 ° C to 200 ° C, more preferably in the range of 10 ° C to 150 ° C, and particularly preferably in the range of 50 ° C to 70 ° C.

[0026]

EXAMPLES Next, examples of the present invention will be described specifically, but the present invention is not limited to the following examples. (Example 1) In a stainless steel autoclave having a glass inner cylinder, 14 g of cyclic (3-butenyl) ethylene ester carboxylic acid and 1.0 mg (1.0 × 10 ⁻⁴ mmol) of a platinum vinylsiloxane xylene solution were weighed. In the air, 2.2 g of dichlorosilane was added to the autoclave, and the mixture was heated to 60 ° C. and stirred. After 6 hours, the reaction was terminated and the reaction mixture was distilled using Kugelrohr. As a result, 5.7 g (15 mmol, yield 8) of a dichlorosilane derivative having two cyclic carbonate groups on silicon was obtained.
8%). A parent peak appeared at 385 in the molecular weight measurement of this substance by GC-MS. Next, a solution prepared by dissolving 3.8 g (10 mmol) of the obtained dichlorosilane derivative in 20 ml of toluene was combined with 2.0 g (10 mmol) of tetraethylene glycol and 1.7 g of pyridine (2 g).
(1 mmol) dissolved in 15 ml of toluene was added dropwise over 20 minutes under a nitrogen gas atmosphere. Then 50
Reaction was performed at ６０60 ° C. for 5 hours. The pyridine hydrochloride precipitated after the reaction was removed, and the solvent was distilled off under reduced pressure.
(9.6 mmol, 96% yield, Mw = 5200) was obtained. 0.8 g of the polymer thus obtained and 0.2 g of lithium perchlorate are dissolved in acetone to form a uniform solution, which is cast on a substrate, and then heated under an argon gas atmosphere to remove the solvent and form a thin film. Obtained. The ionic conductivity of this thin film showed an extremely high value.

[0027]

According to the present invention, a polymer solid comprising a copolymer of a polysiloxane having two substituents having a cyclic ether structure on each silicon and a polyether and an electrolyte salt compound soluble in the copolymer according to the present invention. The electrolyte is excellent in processability, moldability, mechanical strength, flexibility, and the like, and has high ionic conductivity even at a low temperature, so that it can be expected to be applied to electronic devices such as batteries.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01M 6/18 H01M 6/18 E 10/40 10/40 B

Claims (11)

[Claims] 1. A solid random copolymer having a main chain structure comprising a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2), wherein X ¹ and X ^{2 in the} formula (1) are cyclic. A polymer solid electrolyte comprising a copolymer of a polysiloxane and a polyether, which is a substituent containing carbonate, and an electrolyte salt compound soluble in the copolymer. Embedded image Embedded image 2. The polymer solid electrolyte according to claim 1, wherein a polyether copolymer comprising 5 to 40 mol% of the structural unit of the formula (1) and 95 to 60 mol% of the structural unit of the formula (2) is used. (3) a main chain represented by the general formula: And a solid polysiloxane-polyether random copolymer comprising a siloxane structural unit having two substituents containing a cyclic carbonate on each silicon and a structural unit of the formula (2), and the copolymer The solid polymer electrolyte according to claim 1, comprising an electrolyte salt compound soluble in water. However, in the formula, A ¹ and A ² represent a substituted or unsubstituted alkyl group, aryl group, or oxyalkylene group, and n represents an integer of 1 or more. (4) a main chain represented by the general formula: And a solid polysiloxane-polyether random copolymer comprising a siloxane structural unit having two substituents containing a cyclic carbonate on each silicon and a structural unit of the formula (2), and the copolymer The solid polymer electrolyte according to claim 1, comprising an electrolyte salt compound soluble in water. However, in the formula, A ³ and A ⁴ represent a substituted or unsubstituted alkyl group, aryl group, or oxyalkylene group, and n represents an integer of 1 or more. 5. An electrolyte salt compound comprising a cation selected from a metal cation, an ammonium ion, an amidinium ion, and a guanidinium ion, a chloride ion, a bromine ion, an element ion, a perchlorate ion, and a thiocyanate ion. , Tetirafluoroboronate ion, nitrate ion, As
F ₆ ⁻ , PF ₆ —, stearyl sulfonate ion, octyl sulfonate ion, dodecylbenzene sulfonate ion, naphthalene sulfonate ion, dodecyl naphthalene sulfonate ion, R ¹ SO ₃ ⁻ , (R ¹ SO ₂ ) (R ² SO
₂₎ N ^-, and _{^{(R 1 SO 2) (R}} 2 SO 2) (R 3 SO 2)
C ^-, polymer solid electrolyte according to claim 1 which is a compound consisting of selected anions from. Where R ¹ ,
R ² and R ³ are electron-withdrawing groups. 6. R ¹ , R ² and R ³ each independently have 1 carbon atom.
The polymer solid electrolyte according to claim 5, which is a perfluoroalkyl group or a perfluoroaryl group from 1 to 6. 7. The polymer solid electrolyte according to claim 5, wherein the metal cation is a cation of a metal selected from metals belonging to Group 1 or 2 of the periodic table. 8. The solid polymer electrolyte according to claim 5, wherein the metal cation is a cation of a transition metal. 9. The method according to claim 8, wherein the metal cation is Mn, Fe, Co, Ni,
7. The polymer solid electrolyte according to claim 5, which is a cation of a metal selected from Cu, Zn and Ag metals. 10. The compounding ratio of the electrolyte salt compound to the polysiloxane and the polyether copolymer is 0.0001 to 0.0001 mol / mol of the electrolyte salt compound / total mol number of oxygen atoms contained in the copolymer. The solid polymer electrolyte according to any one of claims 1 to 9, which is 3. 11. A battery using the solid polymer electrolyte according to claim 1.