JP2004119343A - Molding material for polymer solid electrolyte, polymer solid electrolyte mold body and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding material for a polymer solid electrolyte suitable for obtaining a polymer solid electrolyte mold body excellent in ion conductivity and mechanical strength, and having excellent moldability, to provide a polymer solid electrolyte mold body formed by molding the molding material; and to provide a method for manufacturing the polymer solid electrolyte mold body by using the molding material. <P>SOLUTION: This molding material for the polymer solid electrolyte comprises a molding material for the polymer solid electrolyte formed of a polyether polymer containing 400-5,000 ppm of moisture; and a polyether polymer containing 400-5,000 ppm. This polymer solid electrolyte mold body is manufactured by mixing an electrolyte salt compound soluble in the polymer and by molding it. <P>COPYRIGHT: (C)2004,JPO

Description

【００５９】
表１が示すように、本発明の成形材料Ａ、Ｂ及びＣを用いると、押出成形時の押出機のバレル圧が低くなり、薄いフィルムを効率よく押し出すことができる。
また、得られるフィルムは、機械的強度が高く粘着性が小さい。このフィルムをリチウムポリマー電池のカソードに使用するといずれもサイクル特性の優れた電池が与えられる（実施例１〜３）。
一方、水分含有量が２００ｐｐｍであるポリエーテル重合体から成る成形材料Ｄ及び成形材料Ｆを用いた比較例１及び比較例４は、押出機のバレル圧力が高すぎてフィルムを安定的に成形することが困難であったり、フィルムの機械的強度が低下したりする。また、水分含有量が５，５００ｐｐｍであるポリエーテル重合体から成る成形材料Ｅを用いた比較例２においては、フィルムの引張強度が弱く、得られたフィルムをリチウムポリマー電池のカソードに使用するとサイクル特性に劣っていた。また、水分含有量が２００ｐｐｍであるポリエーテル重合体に可塑剤としてテトラエチレングリコールジメチルエーテルを混練時に用いた比較例３においては、樹脂圧力の低下が十分でないばかりでなく、フィルムの引張強度が低下し、粘着性も強いため取り扱いが困難であった。
【００６０】
【発明の効果】
本発明の成形材料は、高分子固体電解質成形体に成形する際に成形加工性に優れ、得られた高分子固体電解質成形体は、イオン伝導度が高く、薄くても機械的強度及び離型性に優れる。また、前記高分子固体電解質成形体を有して成る電池は、高出力且つ繰り返し充放電可能である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a molding material for a polymer solid electrolyte suitably used for an electrochemical device such as a battery, a polymer solid electrolyte formed by molding the molding material, and a method for producing the same. The present invention relates to a molding material for a molecular solid electrolyte, a polymer solid electrolyte formed by molding the molding material, and a method for producing the same.
[0002]
[Prior art]
Conventionally, a battery electrolyte is used in a liquid or gel form from the viewpoint of ionic conductivity.However, since there is a risk of damage to equipment due to liquid leakage, a high-strength exterior must be used. Problems have been pointed out, such as the limitation in reducing the size and weight of batteries.
[0003]
On the other hand, polymer solid electrolytes have been studied. The solid polymer electrolyte is expected to be developed in terms of safety because it has excellent flexibility in battery shape because of its excellent workability and flexibility, and because it does not contain an electrolytic solution.
[0004]
For example, attempts have been made to add an alkali metal salt to an ethylene oxide-propylene oxide copolymer and apply it to an ion-conductive solid electrolyte (for example, see Patent Documents 1 to 3). Further improvement in both characteristics is required. Furthermore, when a polymer solid electrolyte is used in a battery or the like, it is handled in a film form in a manufacturing process thereof, and thus it is necessary that the polymer solid electrolyte be a material suitable for film processing. Further, in order to improve the battery output, it is required to make the film as thin as possible.
[0005]
By the way, in order to obtain a polymer solid electrolyte film having excellent mechanical strength even in the form of a thin film, a polymer material having excellent mechanical properties such as tensile modulus is required as a molding material for the electrolyte. Such a polymer material generally has a high melt viscosity at the time of molding and has poor fluidity. Therefore, a plasticizer is usually added to a polymer material for a solid electrolyte for the purpose of lowering the melt viscosity, but a large amount of the plasticizer is required to reduce the melt viscosity to a target value. Also, when a large amount of plasticizer is used, it tends to stick to a roll or the like during molding (particularly during extrusion molding), thereby deteriorating the processability and lowering the mechanical strength of the obtained polymer solid electrolyte molded article. In addition, the ionic conductivity of the polymer solid electrolyte is reduced, and the battery performance using the same is also reduced.
[0006]
[Patent Document 1]
JP-A-61-83249
[Patent Document 2]
JP-A-63-136407
[Patent Document 3]
JP-A-2-24975
[0007]
[Problems to be solved by the invention]
An object of the present invention is to obtain a polymer solid electrolyte molded body having excellent ionic conductivity and mechanical strength, and to obtain a polymer solid electrolyte molding material having excellent moldability, which is formed by molding the molding material. An object of the present invention is to provide a polymer solid electrolyte molded article and a method for producing a polymer solid electrolyte molded article using the molding material.
[0008]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, when a polymer solid electrolyte film is extruded using a polyether polymer containing a specific amount of water, it is melted as compared with a case without water. It has been found that as a result of a drastic decrease in viscosity and an increase in fluidity, the moldability is excellent and the releasability from a roll or the like is also improved. In addition, despite the fact that a molding material containing water was used, the obtained polymer solid electrolyte molded body was found to have a low water content, excellent ionic conductivity, and excellent mechanical strength. Based on the above, the present invention has been completed.
[0009]
Thus, according to the present invention, the following inventions 1 to 7 are provided.
1. (4) A molding material for a solid polymer electrolyte comprising a polyether polymer having a water content of 400 to 5,000 ppm.
2. {Circle around (2)} The molding material according to the above item 1, wherein the polyether polymer contains 70 to 99 mol% of ethylene oxide monomer units (A) and has a weight average molecular weight (Mw) of 100,000 to 1.5 million.
3. (4) A polymer solid electrolyte molded article obtained by mixing and molding the molding material according to (1) or (2) above and an electrolyte salt compound soluble in a polyether polymer.
4. (4) The polymer solid electrolyte molded product according to the above (3), wherein the polymer solid electrolyte molded product is a cathode film.
5. A polymer characterized in that a molding material for a solid polymer electrolyte comprising a polyether polymer having a water content of 400 to 5,000 ppm and an electrolyte salt compound soluble in the polymer are mixed and molded. A method for producing a solid electrolyte molded article.
6. {Circle around (5)} The production method according to the above item 5, wherein the water content of the molded solid polymer electrolyte is 50 to 1,000 ppm.
7. (7) The production method according to the above (5) or (6), which is formed by an extrusion molding method.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The molding material for a solid polymer electrolyte of the present invention comprises a polyether polymer having a water content of 400 to 5,000 ppm.
When the solid polymer electrolyte contains water, it reacts with an electrolyte salt compound or the like to lower the battery performance, so that the water content of the polyether polymer used as the material is generally reduced as much as possible. However, the molding material of the present invention is characterized in that it contains water exceeding a level normally contained in the material of the polymer solid electrolyte.
[0011]
The amount of water contained in the polyether polymer of the molding material of the present invention is preferably from 700 to 4,000 ppm, more preferably from 1,000 to 3,000 ppm. If the water content of the polyether polymer is too low, the melt viscosity during molding may be insufficiently reduced, and a thin polymer solid electrolyte film may not be obtained. On the other hand, when the water content is excessively large, the water content of the obtained solid polymer electrolyte film increases, and the battery performance such as the charge / discharge characteristics of the battery using the same may be deteriorated.
The molding material for a polymer solid electrolyte of the present invention has a remarkable plasticizing effect of water contained in a specific amount thereof.For example, in the case of extrusion molding, a die pressure of an extruder is stabilized at a low level. While the film can be manufactured smoothly, the water content of the obtained film is smaller than the allowable amount as a polymer solid electrolyte. This makes it possible to obtain an output battery.
[0012]
The polyether polymer used in the present invention is not particularly limited as long as it has an oxyalkylene repeating unit obtained by ring-opening polymerization of an oxirane monomer as a main structural unit. The type of the oxirane monomer is not particularly limited, but the polyether polymer used in the present invention preferably has an ethylene oxide monomer unit (A) as a main structural unit. The polymer preferably contains 70 to 99 mol% of all repeating units, and contains 30 to 1 mol% of an oxirane monomer unit (B) copolymerizable with an ethylene oxide monomer unit (A). Is preferred.
[0013]
The amount of the ethylene oxide monomer unit (A) in the polyether polymer is more preferably 80 to 98 mol%, particularly preferably 90 to 97 mol%. If the amount of the ethylene oxide monomer unit (A) is too small, the mechanical strength of the polymer solid electrolyte molded body obtained by molding the polymer solid electrolyte molding material containing the polyether polymer becomes insufficient, In the case of an extruded film, it tends to stick to a roll or the like, so that it may be difficult to form a thin film stably. If the amount of the ethylene oxide monomer units (A) is too large, the ionic conductivity of the obtained polymer solid electrolyte molded article may be reduced, and the battery characteristics at low temperatures may be reduced.
[0014]
The amount of the oxirane monomer unit (B) in the polyether polymer is more preferably 2 to 20 mol%, particularly preferably 7 to 10 mol%.
The oxirane monomer (b) copolymerizable with ethylene oxide, which is a component of the oxirane monomer unit (B), includes alkylene oxide having 3 to 20 carbon atoms, glycidyl ether having 1 to 10 carbon atoms, and vinyl. Compound oxide, and the like.
Specific examples of the alkylene oxide having 3 to 20 carbon atoms include propylene oxide, 1,2-epoxybutane, 1,2-epoxy-isobutane, 2,3-epoxybutane, 1,2-epoxyhexane, and 1,2-epoxyhexane. Chain alkylene oxides such as epoxy octane, 1,2-epoxydecane, 1,2-epoxytetradecane, 1,2-epoxyhexadecane, 1,2-epoxyoctadecane, and 1,2-epoxyeicosane; 1,2-epoxy Cycloalkylene oxides such as cyclopentane, 1,2-epoxycyclohexane, and 1,2-epoxycyclododecane; Specific examples of the glycidyl ether having 1 to 10 carbon atoms include alkyl glycidyl ethers such as methyl glycidyl ether, ethyl glycidyl ether and butyl glycidyl ether; and aryl glycidyl ethers such as phenyl glycidyl ether. Specific examples of the vinyl compound oxide include styrene oxide. These may be used in combination of two or more.
Among these, a chain alkylene oxide is preferable, and propylene oxide and 1,2-epoxybutane having high polymerization reactivity are most preferable.
[0015]
Further, the oxirane monomer (b) may contain a diepoxy compound such as vinylcyclohexene dioxide, butadiene dioxide, ethylene glycol diglycidyl ether, and polyethylene glycol diglycidyl ether, in addition to the above monomers. When these compounds are contained in the oxirane monomer (b), a branched structure can be introduced into the oxirane monomer unit (B) obtained by using these compounds. The content of the diepoxy compound is preferably 0.1 to 5 mol% based on the total amount of the oxirane monomer (b) and the ethylene oxide monomer.
[0016]
When the molding material of the present invention is crosslinked and used as a crosslinked molded article, the oxirane monomer (b) is an oxirane monomer (c) having a crosslinkable functional group as at least a part thereof (crosslinkable monomer). It preferably contains an oxirane monomer (c)). The crosslinkable functional group is a functional group capable of forming a crosslinked structure by heating, irradiation with actinic radiation, or the like. When the crosslinkable oxirane monomer (c) is used as a part of the oxirane monomer (b), when the molding material of the present invention is crosslinked and used as a crosslinked molded article, the crosslinking is facilitated, and the strength is increased. High polymer solid electrolyte film can be easily obtained. In this case, the content of the crosslinkable oxirane monomer (c) is usually 9 mol% or less, preferably 7 mol% or less, more preferably 5 mol% or less, based on all oxirane monomers used for the polymerization of the polyether polymer. Mol% or less. If the content is too large, the molding material tends to undergo a gelling reaction or the like before molding, and the molding processability may be reduced.
[0017]
Examples of the crosslinkable oxirane monomer (c) include a halide of an epoxy compound and an epoxy compound having a vinyl group. Examples of the halide of the epoxy compound include halogenated alkylene oxides such as epichlorohydrin, epibromohydrin, epiiodohydrin, epifluorohydrin and epihalohydrin such as β-methylepichlorohydrin; p-chlorostyrene oxide; Dibromophenyl glycidyl ether; and the like.
Examples of the epoxy compound having a vinyl group include ethylenically unsaturated glycidyl ethers such as vinyl glycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, and o-allylphenyl glycidyl ether; butadiene monoepoxide, chloroprene monoepoxide, 3,4-epoxy-1-pentene, 3,4-epoxy-1-vinylcyclohexene, 1,2-epoxy-5,9-cyclododecadiene and other diene or polyene monoepoxides; 3,4-epoxy-1- Alkenyl epoxides such as butene, 1,2-epoxy-5-hexene, 1,2-epoxy-9-decene; glycidyl acrylate, glycidyl methacrylate, glycidyl crotonate, glycidyl-4-heptenoate, glycidylso Glycidyl esters of ethylenically unsaturated carboxylic acids such as beate, glycidyl linoleate, glycidyl-4-methyl-3-pentenoate, glycidyl esters of 3-cyclohexenecarboxylic acid, glycidyl esters of 4-methyl-3-cyclohexenecarboxylic acid; Is mentioned.
One type of the crosslinkable oxirane monomer (c) may be used alone, or two or more types may be used in combination. Among these, halogenated alkylene oxides and ethylenically unsaturated glycidyl ethers are preferable, and allyl glycidyl ether and epichlorohydrin are particularly preferable.
[0018]
The polymerization catalyst for ring-opening polymerization of the oxirane monomer is not particularly limited. For example, a catalyst obtained by reacting organic aluminum with water and acetylacetone (JP-B-35-15797), triisobutylaluminum, etc. A catalyst obtained by reacting phosphoric acid with triethylamine (Japanese Patent Publication No. 46-27534), a catalyst obtained by reacting triisobutylaluminum with an organic acid salt of diazabiacycloundecene and phosphoric acid (Japanese Patent Publication No. 56-51171) ), A catalyst comprising a partial hydrolyzate of aluminum alkoxide and an organic zinc compound (Japanese Patent Publication No. 43-2945), a catalyst comprising an organic zinc compound and a polyhydric alcohol (Japanese Patent Publication No. 45-7751), Oxirane compounds such as catalysts comprising dialkylzinc and water (JP-B-36-3394). It may be a conventionally known polymerization catalyst as ring-opening polymerization catalyst.
Above all, it is preferable to use a catalyst obtained by reacting triisobutylaluminum with an organic acid salt of diazabiacycloundecene and phosphoric acid, because the amount of toluene-insoluble components which causes a decrease in film strength is reduced.
[0019]
The polymerization solvent is not particularly limited as long as it does not deactivate the polymerization catalyst. For example, aromatic hydrocarbons such as benzene and toluene; linear saturated hydrocarbons such as n-pentane and n-hexane; alicyclic hydrocarbons such as cyclopentane and cyclohexane;
As the polymerization method, a polymerization method such as a solution polymerization method or a solvent slurry polymerization method can be used, but a solvent slurry polymerization method using a solvent such as n-pentane, n-hexane, or cyclopentane is preferably used.
In solvent slurry polymerization, the catalyst must be treated in advance with a monomer that gives a polymer that is insoluble in the solvent and a monomer that gives a polymer that is soluble in the solvent. Is preferred from the viewpoint of the stability of the polymerization reaction system. The treatment of the catalyst may be performed by mixing the catalyst component and a small amount of each of the above monomers, and aging at a temperature of 0 to 100 ° C, preferably 30 to 50 ° C for 3 to 30 minutes. The use of the aged catalyst can prevent the polymer from adhering to the polymerization can.
The polymerization reaction can be carried out at 0 to 100 ° C, preferably 30 to 70 ° C, by any method such as a batch system, a semi-batch system, and a continuous system.
[0020]
The method for adjusting the water content of the polyether polymer used in the present invention is as follows: (1) A predetermined amount of water is added to the polymerization reaction mixture at the end of polymerization, and then the polymer is recovered. (2) When the polymer is recovered from the polymerization reaction mixture and dried, an inert gas containing a certain concentration of water is introduced into the dryer, and the drying conditions are controlled. Or (3) once the polymer is recovered, once dried until the water content is less than 400 ppm, and then dried. A method of contacting with an inert gas containing water, the atmosphere, or the like for a certain period of time to absorb moisture until the water content reaches a target amount, and the like, but is not limited to these methods. Further, these methods may be combined.
For example, in the above method (1), the monomers, polymerization solvent and polymerization catalyst used for the polymerization are all dehydrated, polymerized in a reactor replaced with an inert gas, and then added to the obtained polymerization reaction mixture. Distilled water is added to recover the polyether polymer. At this time, the amount of water to be added to the polymerization reaction mixture, which is necessary to bring the water content in the finally obtained polyether polymer to the target value, is determined in advance by experiments, and the recovery of the polyether polymer is performed. Conditions (drying conditions, etc.) may be determined.
[0021]
The polyether polymer used in the present invention has a weight average molecular weight (Mw) of preferably 100,000 to 1,500,000, more preferably 150,000 to 1,000,000, particularly preferably 200,000 to 600,000, and a molecular weight distribution (Mw). / Mn, where Mn is a number average molecular weight) is preferably a polymer having a molecular weight of 1.5 to 13, more preferably 1.6 to 12, and particularly preferably 1.7 to 11.
When the Mw is within the above range, the flowability and shape retention of the molding material for polymer solid electrolyte using the molding material during film extrusion processing, and the flexibility and mechanical strength of the obtained polymer solid electrolyte film are excellent. If Mw is too large, the melt viscosity is high, and the torque of the molding machine and the die pressure are increased, so that the molding may be difficult. If the Mw is too small, the resulting polymer solid electrolyte film will have insufficient mechanical strength and the film will be easily broken and the film will be sticky, making it difficult to form a thin film stably. On the other hand, if the value of Mw / Mn is too large, the melt viscosity at the time of film forming is high, so that the die pressure increases at the time of extrusion forming, which makes processing difficult, or the film tends to stick to rolls after extrusion. There is a possibility that.
[0022]
To the molding material of the present invention, if necessary, additives such as an antioxidant, a light stabilizer, a lubricant, a lubricant, a flame retardant, a fungicide, an antistatic agent, a coloring agent, a reinforcing material, and a filler are added. You may.
The antioxidant is not particularly limited, but a phenolic antioxidant is preferable, and a hindered phenolic antioxidant is particularly preferable.
The reinforcing agent is not particularly limited, but usually, an oxide such as aluminum, silicon, titanium, zinc, magnesium, and calcium is used. In particular, silica is preferable since it has a high reinforcing effect and a large effect of improving workability. Although the surface area of silica is not particularly limited, it is usually 50 to 400 m2 in terms of a nitrogen adsorption specific surface area (BET method).²/ G, preferably 70-250 m²/ G, more preferably 90 to 150 m²/ G. In general, silanol groups covering the silica surface react with lithium metal or lithium salts and cause battery performance to be impaired. Therefore, silica that is a silica in which the silanol groups on the surface are replaced with hydrophobic groups such as methyl groups Is particularly preferred. The amount of the reinforcing agent is from 0 to 50% by weight, preferably from 0.5 to 30% by weight, more preferably from 1 to 20% by weight, based on the polyether polymer. If the amount of the reinforcing agent is too large, the flexibility of the polymer solid electrolyte film or the cathode film may be impaired, and the ionic conductivity may be reduced.
[0023]
The polymer solid electrolyte molded article of the present invention is obtained by mixing and molding the above-mentioned molding material of the present invention and an electrolyte salt compound soluble in a polyether polymer.
The electrolyte salt compound is a compound that is used in a battery using a solid polymer electrolyte and is capable of moving a cation generated at a cathode in order to combine the cation with an anion generated at an anode. There is no particular limitation as long as it is soluble in the polyether polymer used in the present invention. Further, when the molding material of the present invention is crosslinked and used as a crosslinked molded article, it must be soluble after crosslinking. Specific examples of such an electrolyte salt compound include, for example, fluorine ion, chloride ion, bromide ion, iodine ion, perchlorate ion, thiocyanate ion, trifluoromethanesulfonic acid ion, heptafluoropropylsulfonic acid ion, bis ( Trifluoromethanesulfonyl) imide ion, bis (heptafluoropropylsulfonyl) imide ion, trifluorosulfonimide ion, tetrafluoroboronate ion, nitrate ion, AsF₆ ⁻, PF₆ ⁻Selected from the group consisting of stearylsulfonate, octylsulfonate, dodecylbenzenesulfonate, naphthalenesulfonate, dodecylnaphthalenesulfonate, and 7,7,8,8-tetracyano-p-quinodimethane ion A salt comprising a selected anion and a cation of a metal selected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca and Ba. In particular, when the polymer solid electrolyte molded body is used for a lithium polymer battery, LiBF₄, LiPF₆, LiCF₃SO₃, LiC₄F₉SO₃, LiN (CF₃SO₂)₂, LiN (C₂F₅SO₂)₂Is more preferred.
[0024]
Two or more of these alkali metal salts may be used in combination. The amount of the electrolyte salt compound to be used with respect to the polyether polymer is such that (the number of moles of the electrolyte salt compound) / (the total number of moles of ether oxygen in the copolymer) is usually 0.001 to 5, preferably 0.005 to 3 , More preferably 0.01 to 1. If the amount of the electrolyte salt compound is too large, processability, moldability, and mechanical strength of the obtained polymer solid electrolyte film may be reduced, or ion conductivity may be reduced. On the other hand, if the amount of the electrolyte salt compound is too small, the ionic conductivity of the molded solid polymer electrolyte decreases, and the battery performance decreases.
[0025]
The polymer solid electrolyte molded article of the present invention can be used as a cathode material and an ion conductive electrolyte of a battery, and particularly when used as an ion conductive electrolyte, the molding material of the present invention is cross-linked and molded. It is preferably used as a crosslinked molded article.
When the molding material of the present invention is crosslinked and used as a crosslinked molded article, the molding material is crosslinked after or simultaneously with molding. The crosslinking method is not particularly limited, and includes, for example, a method of blending a crosslinking agent such as a radical initiator, sulfur, mercaptotriazines, and thioureas and crosslinking by heating, and a method of crosslinking by actinic radiation. Among them, a method of crosslinking using a radical initiator such as an organic peroxide and an azo compound, and a method of crosslinking by actinic radiation such as ultraviolet light, visible light, and electron beam are preferable. In the case of crosslinking by these methods, it is preferable to use a polyether polymer obtained by copolymerizing the above-mentioned crosslinkable oxirane monomer (c).
[0026]
Examples of the organic peroxide include ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,2-bis (t Peroxy ketals such as -butylperoxy) octane and n-butyl-4,4-bis (t-butylperoxy) valerate; t-butyl hydroperoxide, cumene hydroperoxide, 2,5-dimethylhexane- Hydroperoxides such as 2,5-dihydroperoxide; di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α′-bis (t-butylperoxy-m- Isopropyl) benzene, 2,5-dimethyl-2,5-bis (t-butyl Dioxy peroxides such as -oxy) hexane and 2,5-dimethyl-2,5-bis (t-butylperoxy) hexine; diacyl peroxides such as benzoyl peroxide; peroxy such as t-butylperoxyacetate Esters and the like.
[0027]
As the azo compound, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) ), 2,2'-azobis (2,4-dimethylvaleronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), 2- (carbamoylazo) isobutyronitrile, 2-phenylazo-4- Azonitrile compounds such as methoxy-2,4-dimethyl-valeronitrile;
2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [1,1 Azoamide compounds such as -bis (hydroxymethyl) ethyl] propionamide} and 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide];
2,2′-azobis (2-methyl-N-phenylpropionamidine) dihydrochloride, 2,2′-azobis [N- (4-chlorophenyl) -2-methylpropionamidine] dihydrochloride, 2,2 ′ -Azobis [N- (hydroxyphenyl) -2-methylpropionamidine] dihydrochloride, 2,2′-azobis [2-methyl-N- (phenylmethyl) propionamidine] dihydrochloride, 2,2′-azobis [2-Methyl-N- (2-propenyl) propionamidine] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [N- (2-hydroxyethyl ) -2-Methylpropionamidine] azoamidine compounds such as dihydrochloride.
[0028]
The compounding amount of the crosslinking agent is usually 0.1 to 10 parts by weight, preferably 0.2 to 7 parts by weight, more preferably 0.3 to 5 parts by weight, per 100 parts by weight of the polyether polymer.
[0029]
When a cross-linking agent is used, a cross-linking aid can be used in combination, if necessary.
Examples of the crosslinking auxiliary used in combination with the organic peroxide crosslinking agent or the azo compound crosslinking agent include metal oxides such as zinc oxide and magnesium oxide; metal hydroxides such as calcium hydroxide; zinc carbonate and basic zinc carbonate. Metal carbonates; fatty acids such as stearic acid and oleic acid; fatty acid metal salts such as zinc stearate and magnesium stearate. When an organic peroxide is used, a compound having at least two crosslinkable unsaturated bonds in the molecule can be used. Specific examples thereof include ethylene dimethacrylate, diallyl phthalate, N, Nm-phenylenedimaleimide, triallyl isocyanurate, trimethylolpropane trimethacrylate, and liquid vinyl polybutadiene. Two or more of these crosslinking assistants can be used in combination. The upper limit of the amount of the crosslinking aid to be used is preferably 20 parts by weight, more preferably 15 parts by weight, particularly preferably 10 parts by weight, per 100 parts by weight of the polyether polymer. If the amount of the crosslinking aid is too large, the crosslinking rate may be too high during crosslinking, bloom may occur on the surface of the crosslinked product, or the crosslinked product may be too hard.
[0030]
When cross-linking is performed with actinic radiation such as ultraviolet rays or electron beams, a photo-crosslinking agent may be added as necessary. Examples of the photocrosslinking agent include benzyldimethylketal, trimethylsilylbenzophenone, benzoin, 4-methoxybenzophenone, benzoinmethyletheranthraquinone, and bis (2.4.6-trimethylbenzoyl) phenylphosphine oxide.
[0031]
For the purpose of improving the ion conductivity, an organic solvent or a plasticizer may be added to the molding material of the present invention. As the organic solvent, aprotic esters and ethers are preferable. As the plasticizer, a polyalkylene glycol having a molecular weight of 5000 or less is preferable. Specific examples of these include propylene carbonate, ethylene carbonate, butylene carbonate, tetrahydrofuran, and ethylene glycol diethyl ether.
[0032]
When the polymer solid electrolyte molded article of the present invention is molded, the above-mentioned polyether polymer, electrolyte salt compound and, if necessary, other compounding agents are mixed in advance by a known method using a roll, a Banbury mixer, or the like. It may be molded after forming, or may be mixed and molded at the time of molding, for example, in an extruder. The mixing order of the above components at the time of mixing is not particularly limited, but after sufficiently mixing components that are hardly decomposed by heat, components that are easily reacted and decomposed by heat (such as a crosslinking agent and a crosslinking accelerator) are shortened. It is preferred to mix on time. When an organic solvent or a plasticizer is added, it may be impregnated for a long time after molding and crosslinking, or may be added at the same time as mixing.
[0033]
Examples of the shape of the polymer solid electrolyte molded body include a plate shape, a sheet shape, a film shape, and the like. As the molding method, an extrusion molding method, a press molding method, an injection molding method, a solution casting method, or the like can be used. However, the polymer solid electrolyte molded article of the present invention has a surface accuracy, a productivity, etc. More preferred are those obtained by extrusion molding. In particular, when the film is formed into a film by extrusion, the fluidity during extrusion and the roll release property of the extruded film are excellent, which is preferable. When the film is formed by an extrusion method, it is most preferable to use a die extrusion method using a twin screw extruder. When the molding material of the present invention is used as a cross-linked molded article by cross-linking molding, depending on the molding method, the crosslinking method, the shape of the cross-linked product, etc., molding and crosslinking may be performed at the same time, or crosslinking may be performed after molding. Is also good.
[0034]
When the polymer solid electrolyte film of the present invention is formed by a twin-screw extrusion method, the forming method is not particularly limited, but an extrusion method generally used for processing rubber can be used. That is, the molding material of the present invention is fed from a hopper of an extruder, wound into a screw, and sent to a head portion by rotation of a screw while softening a polyether polymer by heating from a barrel, and this is installed in a head portion. By passing the film through a film die, an intended film-shaped molded product is obtained. Other compounding agents such as an electrolyte salt compound, an active material and carbon to be compounded when used as a cathode described later, and a plasticizer to be compounded as needed, are mixed through a hopper inlet of a twin-screw extruder when compounded at the time of molding. It may be supplied together with the ether polymer or may be supplied from the middle of the barrel. The ratio of the length (L) of the barrel to the inner diameter (D) is usually 10/1 to 30/1, the barrel temperature is usually 50 to 120 ° C, the head temperature is usually 60 to 130 ° C, and the die temperature is Usually, it is carried out at 70 to 130 ° C.
[0035]
The thickness of the polymer solid electrolyte film obtained by extrusion is usually 10 to 50 μm, preferably 15 to 30 μm. The thickness of the cathode film is usually 20 to 150 μm, preferably 30 to 100 μm. If the thickness is excessively small, the stability of the production may be lacked. On the other hand, if the thickness is excessively large, the ion conductivity may decrease and the output of the battery may not be increased.
[0036]
The polymer solid electrolyte molded article of the present invention can be suitably used as a cathode and an ion-conductive electrolyte of a battery.
The type of battery to which the polymer solid electrolyte molded article of the present invention can be suitably applied is not particularly limited. For example, lithium, potassium, sodium and other alkali metal batteries, zinc-silver chloride, magnesium-silver chloride, magnesium-chloride Examples thereof include a halogen salt battery such as copper, and a proton conductive battery such as a nickel-hydrogen battery. Among them, a lithium battery having high voltage, high energy, and high ionic conductivity in a solid electrolyte is preferable. In addition, the most preferable form of the battery is a battery including only a solid polymer electrolyte without an electrolyte.
[0037]
When the battery is a lithium battery, the battery preferably comprises a cathode film, an anode film and an ion-conductive electrolyte film, and at least one of the cathode film and the ion-conductive electrolyte film is the polymer solid electrolyte of the present invention. It consists of a molded body.
When the polymer solid electrolyte molded article of the present invention is used as an ion conductive electrolyte, it is preferable to use a crosslinked molded article as described above. The ion-conductive electrolyte mainly functions as an ion-conductive electrolyte membrane that substitutes for an electrolyte between the cathode and the anode, and also functions as a separator between the cathode and the anode.
[0038]
When the polymer solid electrolyte molded article of the present invention is used as a cathode of the above-mentioned battery, the active material fine particles and the conductive fine particles are blended when forming the polymer solid electrolyte molding material of the present invention. As the active material, LiCoO₂, Lithium manganese composite oxide, LiNiO₂, V₂O₅, V₆O_ThirteenAnd a lithium-vanadium composite oxide. The average particle size is not particularly limited, but is preferably 0.5 to 30 μm, more preferably 0.6 to 20 μm when the molded article is used in the form of a film. If the particle size is too large, the surface smoothness of the molded article may decrease, and if it is too small, dispersion becomes difficult. The amount of these compounds is preferably 0.1 to 50 times, more preferably 0.3 to 20 times, particularly preferably 0.5 to 10 times the weight of the polyether polymer. When the amount of the active material is too small, the electrode function of the cathode may be insufficient. On the other hand, when the amount is too large, the dispersibility may be reduced and processing may be difficult.
Examples of the conductive fine particles include acetylene black, Ketjen black, graphite and the like, and preferably Ketjen black is used. The amount of these is preferably 1 to 20 parts by weight, preferably 2 to 15 parts by weight per 100 parts by weight of the active material. When the amount of the conductive fine particles is too small, the conductivity of the cathode becomes insufficient, and when it is too large, dispersion becomes difficult.
In the above case, it is preferable to use the solid polymer electrolyte composition of the present invention also as a binder for the active material and the conductive fine particles.
As the anode material, metallic lithium, alloys, oxides and carbon materials capable of inserting and extracting lithium can be used.
[0039]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto. All solvents, monomers, and the like used were those subjected to degassing and dehydration treatment. All operations in Comparative Examples and Examples were performed in an inert gas under anhydrous conditions. Parts and% in Examples and Comparative Examples are based on weight unless otherwise specified.
[0040]
(1) Polymer composition
The polymer composition of the polyether polymer is 500 MHz @ H-NMR and C_Thirteen-Measured using NMR.
[0041]
(2) Water content
The water content of the polyether polymer was determined by measuring the water content of a toluene solution of the polymer with a Karl Fischer moisture meter and subtracting the water measurement value of the solvent toluene used for dissolution as a blank. The water value in the polymer was calculated by conversion with the concentration.
[0042]
(3) Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)
Mw and Mw / Mn were measured using gel permeation chromatography (GPC) under the following conditions.
Equipment: GPC system manufactured by Tosoh Corporation
Column: G7000HHR + GMHHR-H manufactured by Tosoh Corporation
Solvent: DMF (lithium bromide 5 mmol / L)
Flow rate: 1 ml / min Column temperature: 40 ° C
Molecular weight standard: Standard polystyrene manufactured by Polymer Laboratory
[0043]
(4) Barrel pressure
At the time of film extrusion molding, the pressure (barrel pressure) at which the molding material passed through the barrel was measured using a pressure gauge (manufactured by Dynisco) installed in the barrel portion 15 mm before the die tip. When the pressure fluctuated, the average value of the fluctuating pressure region was used. Unit MPa.
[0044]
(5) Film strength
Using a Brabender kneader, 100 parts of the polyether polymer and 22 parts of lithium bistrifluoromethylsulfonylimide are kneaded, and a 2 mm-thick No. 3 dumbbell sample is prepared using the kneaded material according to JIS K6251, and the tensile strength is measured. Was evaluated.
[0045]
(6) Film adhesion
The adhesion of the film was evaluated by testing the releasability of a sample from a polypropylene (hereinafter sometimes referred to as PP) film by the following method. A cathode composition (100 parts of polyether polymer, 330 parts of lithium cobaltate, 21 parts of lithium bistrifluoromethylsulfonylimide, 21 parts of Ketjen black) kneaded with a Brabender kneader is sandwiched between two PP films. At 100 ° C. for 2 minutes and 5 MPa. This was punched into a 1-inch-wide strip, and the PP film on one side was partially peeled off. Both peeled ends were set on a tensile tester, and the peel strength of the positive electrode composition film from the PP film was 23 ° C. At a tensile speed of 500 mm / min.
[0046]
(7) Ionic conductivity
The ionic conductivity was measured by pressing a composition obtained by kneading 20 parts of lithium bistrifluoromethylsulfonylimide in 100 parts of a polyether polymer with a Brabender kneader into a sheet having a thickness of 2 mm, at a temperature of 30 ° C. and a pressure of 1 mmHg. A sheet obtained by vacuum drying in the following for 72 hours was sandwiched between platinum electrodes, and the voltage was 0.5 V and the frequency range was 5 Hz to 13 MHz.
[0047]
(8) Battery cycle characteristics
Lithium bistrifluoromethylsulfonylimide was added to 3000 parts of the polyether polymer such that the ratio of the number of moles of the electrolyte salt to the number of moles of the oxygen atom of the polyether polymer was 0.05, and a photocrosslinking agent benzyldimethylketal was added. Three parts were added and mixed well to obtain a composition for a solid polymer electrolyte. This composition was supplied to a twin screw extruder, and extruded at a screw temperature of 80 ° C., a rotation speed of 150 rpm, and a die temperature of 155 ° C. The extruded film was continuously adhered to a polypropylene (PP) film and crosslinked by UV irradiation. The polymer solid electrolyte film having an average thickness of 50 μm obtained by peeling off the polymer solid electrolyte thin film on the PP film is sandwiched between lithium metal foils of the cathode films obtained in each of the examples and comparative examples, and laminated. The battery was assembled. The charge / discharge characteristics of a battery having a size of 20 mm × 20 mm were examined.
A constant current charge / discharge test was performed in which the battery was charged at 0.2 mA to 4.2 V and discharged at 0.2 mA to 2.7 V. When the discharge capacity at the third cycle was set to 100%, the ratio (percentage) of the discharge capacity at the 10th cycle and the 50th cycle was examined. The larger the value, the smaller the decrease in discharge capacity, which is a good result.
[0048]
Reference Example 1 (Production of molding material A)
The autoclave with a stirrer was dried and purged with nitrogen, and charged with 65.1 parts of triisobutylaluminum, 217.9 parts of toluene, and 121.6 parts of diethyl ether. While the internal temperature was set at 30 ° C., 11.26 parts of phosphoric acid was added at a constant rate over 10 minutes while stirring. To this, 4.97 parts of triethylamine was added, and an aging reaction was performed at 60 ° C. for 2 hours to obtain a catalyst solution.
[0049]
The autoclave with a stirrer was dried and purged with nitrogen, and 1514 parts of n-hexane and 63.3 parts of the above catalyst solution were charged. With the internal temperature set at 30 ° C., while stirring, 7.4 parts of ethylene oxide was added and reacted, then 14.7 parts of an equal weight mixed monomer of ethylene oxide and propylene oxide was added and reacted, and the seed was added. Formed.
[0050]
The internal temperature was set at 60 ° C., and 439.6 parts (92 mol%) of ethylene oxide, 50.4 parts (8 mol%) of propylene oxide, and 427.4 parts of n-hexane were added to the polymerization reaction solution in which the seed was formed. The resulting mixed solution was continuously added at a constant rate over 5 hours. After the addition was completed, the reaction was continued for 2 hours. The polymerization reaction rate was 98%. To the obtained slurry, 42.4 parts of a 5% toluene solution of 4,4'-thiobis (6-tert-butyl-3-methylphenol) as an antioxidant was added and stirred. Thereafter, 0.4 parts of distilled water was added to the slurry which was being stirred to adjust the water content. After filtering the polymer crumb, it was vacuum-dried at 40 ° C. to obtain a powdery polymer.
[0051]
The composition (content of each monomer unit) of the polyether polymer A thus obtained was 91.5 mol% of ethylene oxide units (EO) and 8.5 mol% of propylene oxide units (PO). Was. Further, Mw of the polymer was 350,000, Mw / Mn was 10.2, and water content was 650 ppm.
[0052]
Reference Example 2 (Production of molding materials B to E)
Except that the amount of distilled water added was changed to 0.8 part, 1.5 part, 0.1 part and 2.7 parts, respectively, the same operation as in Example 1 was carried out. Molding materials B, C, D and E comprising polyether polymers of 550 ppm, 3,000 ppm, 200 ppm and 5,500 ppm were obtained. Table 1 shows the ethylene oxide monomer (EO) unit amount, Mw, and Mw / Mn of each polyether polymer.
[0053]
Reference Example 3 (Production of molding material F)
At the time of catalyst preparation, the same operation as in Reference Example 1 was carried out except that the addition amount of phosphoric acid was changed to 14.5 parts, the addition amount of triethylamine was changed to 3.31 parts, and the addition amount of distilled water was changed to 0.1 parts. A molding material F comprising a polyether polymer at 200 ppm was obtained. Table 1 shows the ethylene oxide monomer (EO) unit amount, Mw, and Mw / Mn of the polyether polymer.
[0054]
Example 1
100 parts of molding material A and 22 parts of lithium bistrifluoromethylsulfonylimide were mixed to obtain a composition for a polymer solid electrolyte. This composition was supplied to a twin-screw extruder, and 330 parts of lithium cobaltate and 13 parts of Ketjen black were supplied from the middle of the barrel and extruded at a screw temperature of 80 ° C., a rotation speed of 150 rpm, and a die temperature of 155 ° C. The extruded film was continuously sandwiched between a polypropylene film and an aluminum foil on a roll and wound up.
The barrel pressure in the extruder was measured by the above method, and evaluated as an index of extrusion processability.
In addition, the mechanical strength, adhesiveness (releasability from the polypropylene film), ionic conductivity, and battery cycle characteristics of the film were evaluated by the above methods. The results are shown in Table 1.
[0055]
Example 2 and Example 3
Except for using molding material B and molding material C in place of molding material A, a cathode film was extruded and evaluated in the same manner as in Example 1. The results are shown in Table 1.
[0056]
Comparative Example 1, Comparative Example 2, Comparative Example 4
Except that molding materials D, E and F were used instead of molding material A, a cathode film was extruded and evaluated in the same manner as in Example 1. The results are shown in Table 1.
[0057]
Comparative Example 3
Except that 20 parts of tetraethylene glycol dimethyl ether were supplied to the extruder inlet using the polyether polymer used for the molding material D of Reference Example 2 instead of the polyether polymer used for the molding material A of Reference Example 1. Extrusion molding of the cathode film was performed in the same manner as in Example 1 and evaluated. The results are shown in Table 1.
[0058]
[Table 1]

[0059]
As shown in Table 1, when the molding materials A, B and C of the present invention are used, the barrel pressure of the extruder at the time of extrusion molding is reduced, and a thin film can be extruded efficiently.
Further, the obtained film has high mechanical strength and low adhesiveness. When this film is used as a cathode of a lithium polymer battery, batteries having excellent cycle characteristics are obtained (Examples 1 to 3).
On the other hand, in Comparative Examples 1 and 4 using the molding materials D and F made of a polyether polymer having a water content of 200 ppm, the barrel pressure of the extruder is too high to form a film stably. Or the mechanical strength of the film is reduced. Further, in Comparative Example 2 using the molding material E composed of a polyether polymer having a water content of 5,500 ppm, the tensile strength of the film was low, and when the obtained film was used as a cathode of a lithium polymer battery, the cycle was reduced. The properties were inferior. Further, in Comparative Example 3 in which tetraethylene glycol dimethyl ether was used as a plasticizer at the time of kneading a polyether polymer having a water content of 200 ppm, not only the resin pressure was not sufficiently lowered, but also the tensile strength of the film was lowered. Also, handling was difficult due to strong adhesiveness.
[0060]
【The invention's effect】
The molding material of the present invention is excellent in molding processability when molded into a polymer solid electrolyte molded body, and the obtained polymer solid electrolyte molded body has high ionic conductivity, mechanical strength and mold release even when thin. Excellent in nature. In addition, a battery having the polymer solid electrolyte molded body has high output and can be repeatedly charged and discharged.

Claims (7)

A molding material for a solid polymer electrolyte comprising a polyether polymer having a water content of 400 to 5,000 ppm. The molding material according to claim 1, wherein the polyether polymer contains 70 to 99 mol% of the ethylene oxide monomer unit (A) and has a weight average molecular weight (Mw) of 100,000 to 1.5 million. A solid polymer electrolyte molded article obtained by mixing and molding the molding material according to claim 1 and an electrolyte salt compound soluble in a polyether polymer. The polymer solid electrolyte molded article according to claim 3, wherein the polymer solid electrolyte molded article is a cathode film. A polymer characterized in that a molding material for a solid polymer electrolyte comprising a polyether polymer having a water content of 400 to 5,000 ppm and an electrolyte salt compound soluble in the polymer are mixed and molded. A method for producing a solid electrolyte molded article. The production method according to claim 5, wherein the water content of the molded solid polymer electrolyte is 50 to 1,000 ppm. The method according to claim 5, wherein the composition is formed by an extrusion method.