JP2003016835A - Polymer electrolyte, and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte, having high ionic conductivity at ambient temperature, and having superior film-forming properties, flexibility and mechanical strength. SOLUTION: This polymer solid electrolyte contains a polymer compound comprising a ring-opening-polymerization polymer, provided by ring-opening polymerization of at least one kind of oxetane compound expressed by general formula (1) (where m is independently 1-6; n is independently 1<=n<=20; and R is a 1-12C linear or branched alkyl group), a non-aqueous solvent and an electrolyte salt, and the amount of the nonaqueous solvent with respect to 100 pts.wt. polymer compound is set at 5-400 pts.wt.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ion-conductive polymer electrolyte and a method for producing the same. More specifically, the present invention is a polymer electrolyte comprising a ring-opening polymer of an oxetane compound, which contains an alkali metal ion-based ion conductive carrier such as lithium ion and has high ion conductivity. In addition, the present invention relates to a polymer electrolyte having excellent film-forming properties, flexibility and mechanical strength. The polymer electrolyte of the present invention can be used as an electrolyte for primary batteries, secondary batteries, electrochromic display devices, capacitors and the like.

[0002]

Liquid electrolytes have been conventionally used as electrolytes for primary batteries, secondary batteries, electrochromic display elements, capacitors and the like. However, the liquid electrolyte has a problem of long-term reliability because liquid leakage to the outside of the component, elution of the electrode substance, and the like are likely to occur. On the other hand, when the primary battery, the secondary battery, etc. are formed by using the solid electrolyte, there is no problem such as the liquid leakage and the safety and reliability of the battery are improved. Also, because it can be thinned,
It has the advantages that the battery can be made thinner and stacked, and the parts can be made smaller and lighter. Therefore, solid electrolytes are attracting attention as batteries and other electrochemical device materials,
The research and development are actively carried out.

By the way, solid electrolytes are generally desired to have high ionic conductivity and excellent film-forming properties, flexibility and mechanical strength.

Conventionally, solid electrolyte materials are roughly classified into two types, one consisting of an inorganic material and one consisting of an organic material. Of these, solid electrolytes made of inorganic materials have relatively high ionic conductivity, but since they are crystalline, they have poor mechanical strength, and it is often difficult to mold or form a film into an arbitrary shape, and generally high Because of the price, there are practical problems.

On the other hand, a polymer solid electrolyte using a polymer substance (polymer) can be formed into a thin film having flexibility, and the formed thin film is excellent in flexibility inherent to the polymer. The thin film made of the polymer solid electrolyte has many advantages as compared with the solid electrolyte made of the inorganic material because it can impart the mechanical properties. Therefore, a polymer solid electrolyte using a polymer substance (polymer) has been continuously developed as a solid electrolyte material for high energy density batteries such as lithium secondary batteries.

As such polymer solid electrolytes, solid electrolytes using various polymers have been proposed. For example, there are many solid electrolyte compositions comprising a combination of polymers such as polyethylene oxide, polypropylene oxide, polyethyleneimine, polyepichlorohydrin and polyethylene succinate and inorganic ion salts such as Li and Na, and batteries using these compositions. It has been proposed (for example, JP-A-55-98480).

[0007]

However, these compositions do not have sufficient ionic conductivity, have higher ionic conductivity, and are excellent in film-forming property, flexibility and mechanical strength. Is required.

[0008]

As a result of repeated studies on oxetane derivatives, the present inventors have found that a polymer compound composed of a ring-opening polymer of a specific oxetane compound has high ionic conductivity and film formation. The present invention has been completed by finding that it is a novel polymer electrolyte having excellent properties, flexibility and mechanical strength.

That is, the present invention provides the following general formulas (1) to
At least one oxetane compound represented by (3) (provided that in the formulas (1) and (2), m is 1 to 6 independently, and n is 1 ≦ n ≦ 20 independently. And in the formula (1), R is an optionally branched alkyl group having 1 to 12 carbon atoms), which is a ring-opening polymer, a non-aqueous solvent and an electrolyte salt. The amount of the non-aqueous solvent is 5-40 with respect to 100 parts by weight of the polymer compound.
It relates to a polymer electrolyte characterized by being 0 part by weight.

[0010]

[Chemical 7]

[0011]

[Chemical 8]

[0012]

[Chemical 9]

The present invention also relates to the general formulas (1) to
At least one oxetane compound represented by (3) (provided that in the formulas (1) and (2), m is 1 to 6 independently, and n is 1 ≦ n ≦ 20 independently. And in the formula (1), R is an optionally branched alkyl group having 1 to 12 carbon atoms) in 20 to 800 parts by weight of the non-aqueous solvent based on 100 parts by weight of the oxetane compound. In the above, it relates to a method for producing a polymer electrolyte, which comprises performing ring-opening polymerization in the presence of a catalyst.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. As the electrolyte salt contained in the polymer electrolyte of the present invention, those used in conventional polymer solid electrolytes can be used. For example, LiBr, LiCl,
LiI, LiSCN, LiBF ₄ , LiAsF ₆ , LiC
lO ₄ , CH ₃ COOLi, CF ₃ COOLi, LiCF ₃
SO ₃ , LiPF ₆ , LiN (CF ₃ SO ₂ ) ₂ , LiC
_{(CF 3 SO 2) 3,} LiN (C 2 F 5 SO 2) 2, LiPF 3
(CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) ₃ , LiPF ₄ (C ₂ F
₅ ) ₂ , LiPF ₃ (iso-C ₃ F ₇ ) ₃ , LiPF ₅ (i
so-C ₃ F ₇₎ a lithium salt or the like can be used. In this case, as the electrolyte salt, a single type may be used, or a plurality of types of salts may be used at the same time.

Further, as the electrolyte salt, a salt of the anion of the above-mentioned lithium salt and a salt of an alkali metal other than lithium, such as potassium or sodium, can be used in combination. In the present invention, the composition ratio of the polymer compound and the electrolyte salt is 0.01 to as a molar ratio of the electrolyte salt to the ether chain [-O-] of the polymer compound ([electrolyte salt] / [ether chain]). It is preferably 0.9.

The oxetane compound used in the polymer electrolyte of the present invention has the above formula (1):
The compound represented by (2) having a unit in which m and n are specified can be used alone, and a mixture having a plurality of types of units can be used.

In the method for producing a polymer electrolyte of the present invention, examples of the catalyst used include the electrolyte salt and / or the cation initiator. As a catalyst, Li
BF ₄ , LiAsF ₆ , LiPF ₆ , LiN (CF ₃ S
When at least one electrolyte salt selected from O ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) _{2 and the} like is used, it can be used as an electrolyte salt contained in the polymer electrolyte and is also obtained. Since the electrolyte salt can be uniformly dispersed in the polymer compound, a polymer compound having excellent ionic conductivity and stable characteristics can be provided, which is preferable.

Further, in the method for producing a polymer electrolyte of the present invention, as another catalyst used, at least one kind of cationic initiator such as quaternary ammonium salt, phosphonium salt, sulfonium salt, diazonium salt and iodonium salt is used. Can be mentioned. Specific examples of the cation initiator include quaternary ammonium salts such as tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate and tetrabutylammonium hydrogensulfate; ethyltriphenylphosphonium antimony hexafluoride, tetrabutylphosphonium hexafluoride. Phosphonium salts such as antimony fluoride; triphenylsulfonium boron tetrafluoride, ADEKA OPTON S
P-150 (Asahi Denka Kogyo KK, counter ion: PF ₆ ), Adeka Opton SP-170 (Asahi Denka Kogyo KK, counter ion: SbF ₆ ), Adeka Opton CP-66 (Asahi Denka Kogyo KK, counter ion: SbF ₆ ). ₆ ), ADEKA OPTON CP-
77 (Asahi Denka Kogyo KK, counter ion: SbF ₆ ), San-Aid SI-60L (Sanshin Chemical Industry KK, counter ion: Sb)
F ₆ ), etc. sulfonium salts; benzenediazonium chloride, benzenediazonium bromide, AMERICURE (counter ion: BF ₄ ) manufactured by American Can, ULTRASET (counter ion: BF ₄ , P) manufactured by Asahi Denka Co., Ltd.
Diazonium salts such as F ₆ ); toluene diazonium iodide, diphenyliodonium hexafluoroarsenic, di4-chlorophenyliodonium hexafluoroarsenic, UVE series manufactured by General Electric, manufactured by Minnesota Mining and Manufacturing Co. FC series, Toshiba silicone Co., Ltd. of UV-9310C (counter ion: SbF _6), Photoinitiator manufactured by Rhone Poulenc
Examples thereof include iodonium salts such as 2074 (counterion: (C ₆ F ₅ ) ₄ B).

Furthermore, LiBr, LiCl, LiI, LiSC together with at least one of the above-mentioned cationic initiators.
N, LiBF ₄ , LiAsF ₆ , LiClO ₄ , CH ₃ CO
_{OLi, CF 3 COOLi, LiCF 3} SO 3, LiP
F ₆ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ S
_{O 2) 3, LiN (C} 2 F 5 SO 2) 2, LiPF 3 (CF 3)
₃ , LiPF ₃ (C ₂ F ₅ ) ₃ , LiPF ₄ (C ₂ F ₅ ) ₂ , L
_{iPF 3 (iso-C 3 F} 7) 3, LiPF 5 (iso-C 3
It is also possible to use at least one electrolyte salt such as F ₇ ).

The oxetane compound may be mixed with the cationic initiator or the electrolyte salt and heated or irradiated with light to effect ring-opening polymerization to obtain the polymer electrolyte of the present invention. When the ring-opening polymerization is carried out by heating, it is preferably carried out usually in the presence of 20 to 800 parts by weight of a nonaqueous solvent with respect to 100 parts by weight of the starting oxetane compound.

In the method for producing a polymer electrolyte of the present invention, examples of the non-aqueous solvent used include non-aqueous solvents preferably used for lithium secondary batteries and the like. Specific non-aqueous solvents include, for example, ethylene carbonate (E
C), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC) and other cyclic carbonates, γ-butyrolactone and other lactones, dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate. (DEC) and other chain carbonates, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane, and other ethers,
Examples thereof include nitriles such as acetonitrile, esters such as methyl propionate, methyl pivalate and octyl pivalate, and amides such as dimethylformamide.

These non-aqueous solvents may be used alone or in combination of two or more.
The combination of non-aqueous solvents is not particularly limited, for example,
A combination of cyclic carbonates and chain carbonates, a combination of cyclic carbonates and lactones,
Various combinations such as a combination of three types of cyclic carbonates and chain carbonates can be mentioned. A polar solvent such as ethyl acetate, acetone, methyl isobutyl ketone, methanol, ethanol or isopropyl alcohol which does not inhibit the ring-opening reaction of oxetane can be added to the non-aqueous solvent.

The polymer electrolyte of the present invention is used in the non-aqueous solvent.
Flatten the solution in which the oxetane compound and the catalyst are evenly dissolved.
Cast on a substrate, 30-150 ° C, preferably 40
Evaporate the non-aqueous solvent by heating at ~ 100 ° C.
By carrying out the ring-opening reaction of oxetane in parallel with
It can be suitably manufactured. As a catalyst, LiB
F _Four, LiAsF₆, LiPF₆Has relatively low thermal stability
When using a strong electrolyte salt, heat it at a relatively low temperature
You can also Non-aqueous solvent in the polymer electrolyte of the present invention
The amount of the non-aqueous solvent is excessively high with respect to the polymer compound.
And the strength will decrease, and if it is too small, the conductivity will decrease.
Will be reduced. Therefore, the polymer compound 1
5 to 400 parts by weight, preferably 20 to 100 parts by weight
It is preferable that the amount is up to 200 parts by weight. If necessary,
The obtained polymer electrolyte is impregnated with a non-aqueous solvent to form a non-aqueous solvent.
The amount can be adjusted appropriately.

Further, in the polymer electrolyte of the present invention,
The polymer compound serving as the structural material can be composed only of the polymer compound having the unit of the above formula (1), but in addition to the polymer compound having the unit of the above formula (1), It may also be composed of a polymer blend obtained by blending another soluble high molecular compound. In this case, as the other polymer compound, for example, at least one polymer or copolymer of acrylates such as polyethylene oxide (PEO), ethylene carbonate methacrylate, hydroxyethyl methacrylate, and methoxytetraethylene glycol methacrylate may be mentioned. You can Further, the blending ratio can be appropriately determined according to the ionic conductivity and flexibility required for the polymer electrolyte film.

The polymer electrolyte of the present invention can be used as various electrochemical device materials including high energy density batteries such as lithium secondary batteries. In the present invention, the structure of the lithium secondary battery using the polymer electrolyte is not particularly limited, single-layer or multi-layer positive electrode, negative electrode,
Examples thereof include a coin battery or a polymer battery having a separator, a cylindrical battery or a prismatic battery having a roll-shaped positive electrode, a negative electrode and a roll-shaped separator.
As the positive electrode material (positive electrode active material), a composite metal oxide of at least one metal selected from the group consisting of chromium, vanadium, manganese, iron, cobalt and nickel and lithium is used. Examples of such complex metal oxides include LiCoO ₂ , LiMn ₂ O ₄ , and LiN.
_{iO 2, LiCo 1-x Ni} x O 2 (0.01 <x <
1) and the like. As the negative electrode (negative electrode active material),
Storage of lithium metal, lithium alloy, or lithium
Materials such as releasable carbon materials [pyrolytic carbons, cokes, graphites (artificial graphite, natural graphite, etc.), organic polymer compound combustors, carbon fibers], or composite tin are used. Further, in the lithium secondary battery using the polymer electrolyte of the present invention, the separator is not always necessary and its use can be omitted. Further, for example, it can be used as a binder for an electrode material when forming a current collector of a lithium secondary battery.

In the oxetane compound used in the present invention, as the oxetane compound represented by the general formula (1), polyethylene glycol monomethyl ether oxetane (En3; in the general formula (1), m = 2, n =
3, R = methyl group), polyethylene glycol monomethyl ether oxetane (En9; in the general formula (1), m =
2, n = 9, R = methyl group), polyethylene glycol monoethyl ether oxetane (in the general formula (1), m =
2, n = 3, R = ethyl group), polyethylene glycol monoiso-propyl ether oxetane (m = 2, n = 3, R = iso-propyl group in the general formula (1)), polyethylene glycol monon-butyl ether Oxetane (in the general formula (1), m = 2, n = 3, R = n
-Butyl group), polyethylene glycol monomethyl ether oxetane (in the general formula (1), m = 2, n = 2, R
= Methyl group), polyethylene glycol monoethyl ether oxetane (in the general formula (1), m = 2, n = 2, R
= Ethyl group), polyethylene glycol mono n-butyl ether oxetane (in the general formula (1), m = 2, n =
2, R = n-butyl group) and the like. Further, polypropylene glycol monomethyl ether oxetane (m = 3, n = 2, R = methyl group in the general formula (1)), polypropylene glycol monomethyl ether oxetane (m = 3, n = 3 in the general formula (1), R = methyl group), polypropylene glycol mono n-propyl ether oxetane (in the general formula (1), m = 3, n = 3,
R = n-propyl group) and the like. Furthermore, polyethylene glycol monomethyl ether oxetane (m = 2, n = 6, R = methyl group in the general formula (1)) and the like can be mentioned. Further, as the oxetane compound represented by the general formula (2), diethylene glycol bisoxetane (DDOE; in the general formula (2), m =
2, n = 2), triethylene glycol bisoxetane (TrDOE; m = 2, n = 3 in the general formula (2)), tetraethylene glycol bisoxetane (TeDOE;
In general formula (2), m = 2, n = 4) and the like can be mentioned. Furthermore, 3,3 ′-(oxydimethylene) bis (3-ethyloxetane) (DO represented by the general formula (3) is used.
E) can be mentioned.

The oxetane compound represented by the general formula (2) used in the present invention can be produced, for example, by the following method.

[Synthesis example of diethylene glycol bisoxetane (DDOE; m = 2, n = 2 in the general formula (2)]] 50 g of diethylene glycol (DEG) and 136 g of triethylamine (Et ₃ N) were added to 300 parts of chloroform.
To a solvent such as ml, 140 g of methanesulfonyl chloride (MsCl) is added dropwise under a nitrogen atmosphere so that the temperature does not exceed 10 ° C. After completion of the dropping, the temperature is gradually returned to room temperature to react. Next, water is added to the reaction solution to collect an organic layer, the organic layer is washed with water, dehydrated, and then chloroform is distilled off to obtain an oil layer. Next, 92 g of 3-ethyl-3-hydroxymethyloxetane (EHO) and 68 g of 35% sodium hydroxide solution were added to a solvent such as 300 ml of toluene, and a predetermined amount of water was removed azeotropically, and then 40 to 50 ° C. Slowly add the previously synthesized oil layer at the temperature of
After reacting for about an hour, the mixture is reacted at 110 ° C. for about 4 hours. Next, water is added to collect the toluene layer, and the toluene layer is washed with water, dried, and then distilled under reduced pressure to obtain DDOE (1
mmHg, 178 ° C) is obtained.

In the same manner as described above, by using triethylene glycol or tetraethylene glycol instead of ethylene glycol, triethylene glycol bisoxetane (TrDOE (1 mm
Hg, 195 ° C.); in the general formula (2), m = 2, n =
3) or tetraethylene glycol bisoxetane (T
eDOE (1 mmHg, 203 ° C.); m = 2, n = 4 in the general formula (2) can be synthesized.

The oxetane compound represented by the general formula (1) can be produced, for example, by the following method.

[En3 (in the general formula (1), m = 2, n =
3, Synthesis Example of R = Methyl Group] 91 g of 3-ethyl-3-hydroxymethyloxetane (EHO) and 115 g of triethylamine (Et ₃ N) were added to a solvent of 300 ml of toluene, and methanesulfonyl chloride was added so as not to exceed 10 ° C. After slowly adding (MsCl), the mixture is stirred at room temperature for reaction. After completion of the reaction, water and toluene are added to collect the toluene layer, and the toluene layer is washed with water, dried, and then distilled under reduced pressure to give 3-ethyl-3-.
(Methanesulfonyl) oxymethyl oxetane (EHO
-Ms (2 mmHg, 120 ° C)) is obtained.

Then, the obtained EHO-Ms is reacted with Na salt of triethylene glycol monomethyl ether (NaO (CH ₂ CH ₂ O) ₃ CH ₃ ) in a solvent such as toluene, washed with water and distilled under reduced pressure. As a result, En3 is obtained. Also in the case of En9, it can be obtained in the same manner as En3 except that purification is performed by a toluene extraction operation.

Further, 3,3 'represented by the general formula (3)
-(Oxydimethylene) bis (3-ethyloxetane)
(DOE) is 3-ethyl-3- (methanesulfonyl) oxymethyloxetane (EHO-Ms) and 3-ethyl-
It can be obtained by reacting with 3-hydroxymethyloxetane (EHO) in the presence of an alkali.

[0034]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Example 1 [Preparation of Electrolyte Film Containing Non-Aqueous Solvent] Propylene carbonate (PC) and dimethyl carbonate (DMC) preliminarily adjusted to 3 times the weight of the oxetane compound.
Non-aqueous solvent (weight ratio: PC / DMC = 1/2) with LiB
F ₄ was added, and the mixture was thoroughly stirred to form a uniform solution, and the oxetane compound (D
The oxetane compound obtained in the above-mentioned synthesis example was added so that [Li ion] / [-O-unit] = 0.50 with respect to the ether chain of DOE, TrDOE, TeDOE), and stirred until completely dissolved. After that, a film was formed by the cast method. That is, the solution was placed in a Teflon (R) petri dish having a smooth bottom surface, and the remaining amount of the non-aqueous solvent was a predetermined amount at about 70 ° C for about 1 hour in a thermostat set to a temperature range of 40 to 60 ° C under a nitrogen atmosphere. The non-aqueous solvent was removed so as to obtain a ring-opening polymer of the oxetane compound, and thus a non-aqueous solvent-containing electrolyte film was obtained.

The non-aqueous solvent-containing electrolyte film thus obtained was a highly flexible film. The thickness of this film can be appropriately adjusted to a predetermined value according to the purpose, but here, in order to evaluate the ionic conductivity as described later, a film having a thickness of 50 to 150 μm was prepared ( Sample Nos. 1-9).

[Evaluation of Ionic Conductivity] The ionic conductivity of the obtained electrolyte film containing a non-aqueous solvent was evaluated as follows. That is, an electrolyte film containing a non-aqueous solvent is pressure-bonded to an electrode of a stainless steel plate, a temperature variable thermostat is set to a predetermined temperature and an evaluation cell is put therein, and the evaluation cell is in a steady state at that temperature. It was left to stand for about 1 hour.
Then, the ionic conductivity was analytically calculated from the semi-circular arc portion obtained by the constant voltage complex impedance method (AC amplitude voltage 10 mV, AC frequency band 1 Hz to 500 kHz, temperature 30 ° C.). The results are shown in Table 1 together with the kind of the raw material oxetane compound, the electrolyte salt / -O- (molar ratio), and the non-aqueous solvent content (% by weight in the electrolyte film).

[0037]

[Table 1]

As can be seen from Table 1, the polymer electrolyte membranes of the examples have a ionic conductivity in the temperature region near room temperature, which is a conventional polymer electrolyte membrane composed of PEO or another polymer compound and an alkali metal salt. It was confirmed that it was significantly higher than the ionic conductivity in the temperature region near room temperature.

[0039]

According to the present invention, it is possible to obtain a polymer electrolyte having high ionic conductivity even near room temperature and having excellent film-forming property, flexibility and mechanical strength.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01B 13/00 H01B 13/00 Z H01M 10/40 H01M 10/40 B // H01M 6/18 6/18 E F-term (reference) 4J002 CH031 DD027 DD057 DE187 DE197 ED026 EH006 EH036 EL066 EL106 EP016 ET006 EW007 FD117 FD206 GQ00 4J005 AA07 AA09 BA00 BB02 5G301 CA16 CA30 CD01 5H024 AA00 AA02 AA03 AA12 FF15 FF16 FF17 FF18 FF19 FF20 FF23 FF31 5H029 AJ02 AJ11 AJ14 AK03 AL01 AL06 AL07 AL12 AM00 AM02 AM03 AM04 AM05 AM07 AM16 CJ02 CJ11 DJ09 DJ10 EJ12 HJ01 HJ02 HJ14

Claims (6)

[Claims] 1. At least one oxetane compound represented by the following general formulas (1) to (3) (wherein, in formulas (1) and (2), m is independently 1 to 6, n is independently 1 ≦ n ≦ 20, and the formula (1)
In the formula, R is an optionally branched alkyl group having 1 to 12 carbon atoms. ) A polymer electrolyte comprising a ring-opening polymer as a polymer compound, a non-aqueous solvent and an electrolyte salt, wherein the amount of the non-aqueous solvent is 5 to 400 parts by weight relative to 100 parts by weight of the polymer compound. . [Chemical 1] [Chemical 2] [Chemical 3] 2. The molar ratio of the electrolyte salt to the ether chain [—O—] of the polymer compound is [(electrolyte salt] / [ether chain]).
The polymer electrolyte according to claim 1, which is 0.01 to 0.9. 3. At least one oxetane compound represented by the following general formulas (1) to (3) (wherein, in formulas (1) and (2), m is independently 1 to 6, n is independently 1 ≦ n ≦ 20, and the formula (1)
In the formula, R is an optionally branched alkyl group having 1 to 12 carbon atoms. ) Is subjected to ring-opening polymerization in the presence of a catalyst in 20 to 800 parts by weight of a non-aqueous solvent with respect to 100 parts by weight of the oxetane compound. [Chemical 4] [Chemical 5] [Chemical 6] 4. The method for producing a polymer electrolyte according to claim 3, wherein the ring-opening polymerization is carried out at 30 to 150 ° C. 5. The method for producing a polymer electrolyte according to claim 3, wherein the catalyst is an electrolyte salt and / or a cationic initiator. 6. A lithium secondary battery comprising the polymer electrolyte according to claim 1.