JP2006244801A - Manufacturing method of laminate for lithium battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electrolyte-film/positive-electrode-film laminate which is high in lithium ion conductivity and lithium ion transference number and high in adhesiveness between films. <P>SOLUTION: In the manufacturing method of the laminate for a lithium battery, an electrolyte film A and a positive electrode film B are laminated, where the electrolyte film A contains a polyether polymer and a lithium salt, and the positive electrode film B contains a polyether polymer, an active material, a conductivity imparting agent, and a lithium salt. The electrolyte film A and the positive electrode film B are films formed by extrusion molding. The electrolyte film A contains a liquid compound which has a alkylene oxide repeating unit in a viscosity range from 100 to 2,000 mPa s at 25°C. A laminate of both films A, B is press-bonded by rollers with a gap of 1/1.3 to 1/1.02 of the thickness sum of the both films formed therebetween. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a laminate of an electrolyte film and a positive electrode film for a lithium battery, and more specifically, a method for producing the laminate having a high lithium ion conductivity and a high transport number, and the production method. The present invention relates to a lithium battery having a laminate.

  Since lithium batteries have high energy density and large electromotive force, they are indispensable as power sources for mobile devices such as mobile phones and notebook computers, as well as small electric devices. 2. Description of the Related Art In recent years, developments have been made to solve the drawbacks of electrolyte solution leakage and evaporation of lithium batteries by using a polymer solid electrolyte. In particular, a film made of a polyether polymer such as an ethylene oxide-propylene oxide copolymer is expected as a solid electrolyte having ion conductivity for a secondary battery because an electrolyte salt compound such as a lithium salt compound is soluble. ing. However, since the ionic conductivity of this film is still insufficient, there is a difficulty that a large current cannot be obtained due to insufficient current density of charge / discharge. Moreover, since the adhesiveness with the positive electrode film and negative electrode film which are each laminated | stacked on the front and back of an electrolyte film is lacking, it has the problem that battery characteristics, such as a fall of initial capacity, are inferior.

To solve this problem, Patent Document 1 discloses that a boric acid ester compound having an alkylene oxide repeating unit is dissolved in a low boiling point organic solvent together with an ionic compound and a polymerizable organic compound and cast, and then polymerized while removing the solvent. It was proposed to obtain an electrolyte film by polymerizing organic compounds. However, this film has a problem that an ionic compound is precipitated in the process of static polymerization, and the film is thick as 0.5 mm, which is electrochemically inhomogeneous and the output of the battery is low. In Patent Document 2, an alkylene oxide repeating unit-containing boron compound having a (meth) acryloyl group is polymerized by pouring into a fluororesin boat in the presence of a radical polymerization initiator and an electrolyte salt compound, and an electrolyte film having high ion conductivity is obtained. It was reported that it was obtained. However, this film is also electrochemically inhomogeneous as described above, and it cannot be said that the output of the battery is improved. Patent Document 3 discloses an ion transport number obtained by spreading a mixture of a crosslinkable group-containing polyether oligomer, a polyether having a boron atom in the molecular structure and an electrolyte salt compound on a stainless steel foil and irradiating with an electron beam. A high, 95 μm thick polymer solid electrolyte has been disclosed. However, the problem of the battery output due to the inhomogeneity of this film is exactly the same as the above two and unsolved, and in any electrolyte film described in the above three patent documents, the positive electrode film and the negative electrode film The adhesion at the time of lamination is not improved.
JP 2001-155571 A JP 2004-182982 A JP 2003-92138 A

  An object of the present invention is to provide a method for producing an electrolyte film-positive electrode film laminate having a high lithium ion transport number and excellent adhesion between films, and a high-power lithium battery having the laminate obtained by the production method. There is to do.

  As a result of diligent research to achieve the above object, the present inventors have utilized a thin film obtained by an extrusion molding method, an electrolyte film containing a polyether polymer, a lithium salt, and a specific plasticizer; The laminate is obtained by pressure-bonding a polyether polymer, an active material, a conductivity-imparting agent and a positive electrode film containing a lithium salt with a roller having a specific gap. The present invention has been completed based on the findings.

Thus, according to the present invention, the following items 1 to 10 are provided.
1. For a lithium battery obtained by laminating an electrolyte film (A) containing a polyether polymer and a lithium salt and a positive electrode film (B) containing a polyether polymer, an active material, a conductive agent and a lithium salt A method for producing a laminate,
The electrolyte film (A) and the positive electrode film (B) are formed by an extrusion method,
The electrolyte film (A) contains a liquid compound having an alkylene oxide repeating unit with a viscosity at 25 ° C. of 100 to 2,000 mPa · s,
(A), (B) Lithium battery characterized in that lamination of both films is performed by pressure bonding with a roller having a gap of 1 / 1.3-1 / 1.02 of the total thickness of both films. Method for manufacturing a laminated body.
2. 2. The method for producing a laminate for a lithium battery as described in 1 above, wherein the roller has a surface temperature of 30 to 120 ° C.
3. The manufacturing method of the laminated body for lithium batteries of said 1 or 2 whose said electrolyte film (A) adjusts the film extruded by the extruder to thickness 10-50 micrometers.
4). The manufacturing method of the laminated body for lithium batteries in any one of said 1-3 whose said positive electrode film (B) adjusts the film extruded by the extruder to 30-90 micrometers in thickness.
5. The manufacturing method of the laminated body for lithium batteries in any one of said 1-4 whose said positive electrode film (B) laminated | stacked a positive electrode electrical power collector previously in the side which does not contact the electrolyte film (A).
6). The positive electrode film (B) further contains a liquid compound having an alkylene oxide repeating unit having a viscosity at 25 ° C. of 100 to 2,000 mPa · s. A method for producing a laminate for a lithium battery.
7). Any of 1 to 6 above, wherein the liquid compound having an alkylene oxide repeating unit having a viscosity at 25 ° C. of 100 to 2,000 mPa · s is a compound having the chemical formula represented by the following general formula (1) or (2) A method for producing a laminate for a lithium battery according to claim 1.
(R ¹ ) (R ² ) C (CH ₂ OX) ₂ (1)
R ³ B (OX) ₂ (2)
Here, R ¹ is H, CH ₃ or CH ₂ CH ₃ , R ² is H, CH ₃ , CH ₂ CH ₃ , CH ₂ OX or OX, R ³ is OX, phenyl group, vinylphenyl group or methoxy A phenyl group, X represents (AO) _n Y, AO represents an alkylene oxide repeating unit, Y represents H, C _m H _{2m + 1} or C _m H _2m-1 , and n and m are integers of 1 to 50 It is.
8). 8. The lithium battery according to 7 above, further containing a compound having a chemical formula represented by the following general formula (3) as a liquid compound having an alkylene oxide repeating unit having a viscosity at 25 ° C. of 100 to 2,000 mPa · s. A manufacturing method of a layered product.
R ⁴ (R ⁵ ) (R ⁶ ) ZX (3)
Here, R ⁴ represents C _k H _{2k + 1} or C _k H _2k-1 , R ⁵ and R ⁶ represent H, CH ₃ , C ₂ H ₅ or OCH ₃ , Z represents COO or O, k represents It is an integer of 3-60.
9. The manufacturing method of the laminated body for lithium batteries in any one of said 1-8 whose reduced viscosity of the polyether polymer which is a component of an electrolyte film (A) is 0.6-25 dl / g at least.
10. The lithium battery which has a laminated body for lithium batteries obtained by the manufacturing method in any one of said 1-9.

  INDUSTRIAL APPLICABILITY According to the present invention, there are provided a method for producing an electrolyte film-positive film laminate having a high lithium ion transport number and excellent adhesion between films, and a high-power lithium battery having the laminate obtained by the production method. .

  The method for producing a laminated body for a lithium battery according to the present invention includes an electrolyte film (A) containing a polyether polymer and a lithium salt, and a positive electrode containing a polyether polymer, an active material, a conductivity-imparting agent, and a lithium salt. A method for producing a laminate for a lithium battery in which a film (B) is laminated, wherein the electrolyte film (A) and the positive electrode film (B) are formed by an extrusion method, and the electrolyte film (A ) Contains a liquid compound having an alkylene oxide repeating unit with a viscosity at 25 ° C. of 100 to 2,000 mPa · s, and the lamination of both films is 1 / 1.3 to the total thickness of both films. It is characterized by being pressure-bonded with a roller having a gap of 1 / 1.02.

  The polyether polymer used as a constituent material of the electrolyte film (A) is not particularly limited as long as it has an alkylene oxide repeating unit obtained by ring-opening polymerization of an oxirane monomer as a main structural unit. The oxirane monomer is not particularly limited, but when the ethylene oxide monomer (a) is used as at least one component of the oxirane monomer used for the polymerization, the electrolyte film (A) obtained by molding the monomer is mechanical strength. It is preferable because it is excellent. In the polyether polymer (A) used in the present invention, the molar ratio of the content of the ethylene oxide monomer (a) unit and the oxirane monomer (b) unit copolymerizable with ethylene oxide is [monomer (A) number of moles of unit / number of moles of monomer (b) unit], usually 85/15 to 99/1, preferably 90/10 to 99/1, more preferably 92/8 to 99 /. 1. If the ethylene oxide monomer (a) unit content is too small, the film may easily stick to a cooling roll or the like. On the other hand, if the ethylene oxide monomer (a) unit content is too large, it may be difficult to obtain a smooth film.

  Examples of the oxirane monomer (b) copolymerizable with ethylene oxide include alkylene oxides having 3 to 20 carbon atoms, glycidyl ethers having 4 to 10 carbon atoms, oxides of aromatic vinyl compounds, vinyl groups on these oxirane monomers. And a crosslinkable oxirane monomer into which a crosslinkable functional group such as a hydroxyl group or an acid anhydride group is introduced.

The oxirane monomer (b) copolymerizable with ethylene oxide may be used alone or in combination of two or more. In the present invention, the alkylene oxide having 3 to 20 carbon atoms is used. It is preferable to use glycidyl ether having 4 to 10 carbon atoms or the like as at least one component, and more preferable to use alkylene oxide having 3 to 20 carbon atoms as at least one component. Propylene oxide is preferable as the alkylene oxide having 3 to 20 carbon atoms.
Examples of the crosslinkable oxirane monomer include oxirane monomers such as alkylene oxides having 3 to 20 carbon atoms and glycidyl ether having 4 to 10 carbon atoms, light such as vinyl groups, hydroxyl groups, and acid anhydride groups. Alternatively, it is preferable to use a crosslinkable oxirane monomer having a crosslinkable group that can be crosslinked with peroxide, and among them, it is more preferable to use a crosslinkable oxirane monomer having a vinyl group such as vinyl glycidyl ether and allyl glycidyl ether. preferable.

  The polymerization catalyst for ring-opening polymerization of the oxirane monomer is not particularly limited. For example, a catalyst obtained by reacting water and acetylacetone with organic aluminum (Japanese Patent Publication No. 35-15797), triisobutylaluminum 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 diazaviacycloundecene and phosphoric acid (Japanese Patent Publication No. 56-51171) ), A catalyst comprising a partially hydrolyzed 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. 45-7951), Oxirane compounds such as catalysts comprising dialkylzinc and water (Japanese Patent Publication No. 36-3394) It may be a conventionally known polymerization catalyst as ring-opening polymerization catalyst.

As a polymerization method for obtaining the polyether polymer, a polymerization method such as a solution polymerization method using an organic solvent in which the produced polymer is dissolved or a solvent slurry polymerization method using an organic solvent in which the produced polymer is insoluble is used. However, a solvent slurry polymerization method using a solvent such as n-pentane, n-hexane, or cyclopentane is preferable.
Among the solvent slurry polymerization methods, a two-stage polymerization method in which seeds are polymerized in advance and then seed particles are enlarged is preferable because the amount of scale attached to the inner wall of the reactor is small.

The weight average molecular weight (Mw) of the polyether polymer (A) is a polystyrene-converted value by a gel permeation method using dimethylformamide as a solvent, and is usually from 100,000 to 1,500,000, preferably from 150,000 to 1,000,000. Preferably, it is 200,000 to 600,000, and the molecular weight distribution index Mw / Mn (where Mn is the number average molecular weight) is usually 1.5 to 13, preferably 1.6 to 12, more preferably 1. 7-11.
When the Mw is in the above range, the fluidity and shape retention when producing a film by extruding a polyether polymer composition using the same are excellent. The obtained electrolyte film (A) is excellent in flexibility and mechanical strength. If Mw is too large, the torque of the extruder and the die pressure increase, which may make molding difficult. If Mw is too small, mechanical strength of the obtained electrolyte film (A) is insufficient and easily broken, and the film is likely to stick, so that it may be difficult to stably produce a thin film. There is.
If the value of Mw / Mn is too large, the melt viscosity at the time of film forming becomes high, the die pressure increases at the time of extrusion forming, making it difficult to process, or the surface smoothness and thickness uniformity of the extruded film May be damaged.

  The polyether polymer preferably has a reduced viscosity of 0.6 to 25 dl / g, more preferably 0.7 to 20 dl / g, and particularly preferably 0.8 to 15 dl / g. Here, the reduced viscosity is a value measured according to JIS K6300. The reduced viscosity can be determined by measuring the viscosity of a solution obtained by dissolving 0.25 g of a polyether polymer in 100 g of toluene and the viscosity of toluene at 25 ° C. using an Ubbelohde viscometer.

The lithium salt of the electrolyte salt compound used as the constituent material of the electrolyte film (A) in the present invention is not particularly limited as long as it is soluble in the polyether polymer. Examples of such lithium salts include halogen ions, perchlorate ions, thiocyanate ions, trifluoromethanesulfonate ions [CF ₃ SO ₃ ⁻ ], bis (trifluoromethanesulfonyl) imide ions [N (CF ₃ SO ₂ ). ₂ ^-], bis (heptafluoropropyl) imide ion _{[N (C} 2 F 5 _{SO 2) 2} ^-], trifluoromethyl sulfonimide ion, tetrafluoroborate periodate ions [BF ₄ ^-], nitrate ion, AsF ₆ ^-, PF 6 ^_-, stearyl sulfonate ion, and anions such as octyl sulfonate ion, and a salt comprising a lithium cation. Among these lithium salts, LiBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ and LiN (C ₂ F ₅ SO ₂ ) ₂ are more preferable. These lithium salts may be used alone or in combination of two or more.

  The content of the lithium salt in the electrolyte film (A) is usually 5 to 70 parts by weight, preferably 8 to 60 parts by weight, and more preferably 10 to 55 parts by weight with respect to 100 parts by weight of the polyether polymer. is there. If the lithium salt content of the electrolyte film (A) is too low, the ionic conductivity of the electrolyte film may be reduced. Conversely, if it is too high, the mechanical strength will be reduced and the adhesiveness will increase, making production difficult. There is a possibility.

The liquid compound (L) having a viscosity at 25 ° C. of 100 to 2,000 mPa · s and having an alkylene oxide repeating unit, which is used as a constituent material of the electrolyte film (A), is dissolved in the polyether polymer to form a plasticizer. It exhibits an action, improves adhesion with the positive electrode film laminated on the surface of the electrolyte film, and also improves adhesion when the negative electrode film is laminated on the back surface. Furthermore, a liquid compound (L) has the effect | action which improves the ion mobility in an electrolyte film (A).
The preferred viscosity of the liquid compound (L) is 120 to 1700 mPa · s, more preferably 150 to 1500 mPa · s. If the viscosity of the liquid compound (L) is too low, the mechanical strength of the electrolyte film (A) may be reduced, and the adhesiveness may increase and production may be difficult. Adhesion may be reduced.

A suitable liquid compound (L) is a compound having a chemical formula represented by the following general formula (1) or (2).
(R ¹ ) (R ² ) C (CH ₂ OX) ₂ (1)
R ³ B (OX) ₂ (2)
Here, R ¹ is H, CH ₃ or CH ₂ CH ₃ , R ² is H, CH ₃ , CH ₂ CH ₃ , CH ₂ OX or OX, R ³ is OX, phenyl group, vinylphenyl group or methoxy A phenyl group, X represents (AO) _n Y, AO represents an alkylene oxide repeating unit, Y represents H, C _m H _{2m + 1} or C _m H _2m-1 , and n and m are integers of 1 to 50 It is.
Examples of such liquid compounds (L) include trimethylolpropane polyoxyethylene ether, trimethylolpropane trimethoxytripolyoxyethylene ether, trimethoxyglycerin polyoxyethylene ether; tri (methoxypolyethylene glycol) borate, di (methoxypolyethylene). Englycol) -p-vinylphenylborate, di (methoxypolyethyleneglycol) -p-methoxyphenylborate, methoxypolyethyleneglycol-p-vinylphenylborate and the like.

Further, as the liquid compound (L), the compound having the chemical formula represented by the general formula (1) or (2) may further contain a compound having the chemical formula represented by the following general formula (3). .
R ⁴ (R ⁵ ) (R ⁶ ) ZX (3)
Here, R ⁴ represents C _k H _{2k + 1} or C _k H _2k-1 , R ⁵ and R ⁶ represent H, CH ₃ , C ₂ H ₅ or OCH ₃ , Z represents COO or O, k represents It is an integer of 3-60.
Examples of such compounds include methoxymyristin polyoxyethylene ether and methoxy polyoxyethylene oleate.

  The content of the liquid compound (L) in the electrolyte film (A) is usually 10 to 500 parts by weight, preferably 20 to 300 parts by weight, more preferably 30 to 150 parts by weight based on 100 parts by weight of the polyether polymer. Parts by weight. If the content of the liquid compound (L) in the electrolyte film (A) is too small, the ion conductivity at room temperature or lower of the electrolyte film (A) may be lowered, and the adhesion with the electrode layer may be insufficient. On the other hand, if the amount is too large, the mechanical strength is lowered and the tackiness may be increased.

The electrolyte film (A) is preferably a crosslinked molded body. In order to obtain this crosslinked molded article, a crosslinking agent is added to the composition before molding, and crosslinking is performed after molding or simultaneously with molding. The crosslinking method is not particularly limited, and examples thereof include a method of blending a crosslinking agent such as a radical initiator, sulfur, mercaptotriazines, thioureas and the like, and crosslinking by heating, and a method of crosslinking by actinic radiation. Among them, a method in which a radical initiator such as an organic peroxide or an azo compound is blended in the composition before molding and crosslinking is performed by heating, or a photocrosslinking agent is blended in the active radiation such as ultraviolet rays, visible rays, or electron beams. A method of crosslinking is preferred.
The blending amount of the crosslinking agent when blending various crosslinking agents as described above into the molding composition for obtaining the electrolyte film (A) is usually 0.1 to 100 parts by weight of the polyether polymer. 10 parts by weight, preferably 0.2 to 7 parts by weight, more preferably 0.3 to 5 parts by weight.

To produce the electrolyte film (A), the polyether polymer, the lithium salt, and the liquid compound (L) are mixed with an aprotic compound that is used in the cross-linking agent as required, and further in an electrolytic solution. A molding composition obtained by mixing various components including a carbonate compound, an antioxidant, a light stabilizer, a lubricant, a flame retardant, an antifungal agent, an antistatic agent, a colorant, a reinforcing material, a filler, It is fed into an extruder equipped with a film die and formed into a film. When the radical crosslinking agent is mix | blended with the composition for shaping | molding, it is set as a crosslinked body at the time of shaping | molding or subsequent heating. When a photocrosslinking agent is blended, the film after molding is irradiated with actinic radiation to form a crosslinked product.
Mixing for preparing the molding composition may be carried out in advance with a brabender, a Banbury mixer, a kneader, a mixing roll, a pellet making extruder, or the like prior to extrusion molding, or in a raw material hopper of an extruder for film forming. Components such as a polyether polymer may be sequentially added and mixed in a kneading zone of an extruder. By this mixing, the solid compounding agent can also be uniformly dispersed in the polyether polymer.

  The temperature of the extruder kneading part for stably producing the electrolyte film (A) is usually 40 to 200 ° C, preferably 50 to 150 ° C, more preferably 55 to 130 ° C. If the temperature of the kneading part is too low, there is a risk that the dispersion of the compound will be poor and the battery characteristics will deteriorate, and conversely if the temperature of the kneading part is too high, the compound will undergo thermal decomposition and the battery characteristics may be deteriorated. There is sex.

The electrolyte film (A) extruded from the die of the extruder is usually wound around a take-up roll via a cooling roll. It is preferable to place a cast roll in front of the take-up roll, detect the thickness and tension of the film with the respective detection means, and feed back the results to the extruder and the cooling roll. The thickness of the electrolyte film (A) controlled by a cast roll or the like is preferably 10 to 50 μm, more preferably 15 to 45 μm, and particularly preferably 18 to 40 μm.
By making the surface of the cooling roll into a mirror surface, the surface of the film extruded from the die can be finished more smoothly.

  The polyether polymer used as the constituent material of the positive electrode film (B) is not necessarily the same as the polyether polymer used as the constituent material of the electrolyte film (A). It is preferable to have a reduced viscosity in the above range.

The active material used as the constituent material of the positive electrode film (B) can be used without limitation as long as it is usually used for a positive electrode of a battery. Examples of such active materials include lithium cobalt oxide, lithium manganese composite oxide, LiNiO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , lithium vanadium composite oxide, and the like.
The average particle size of the active material is usually 0.1 to 30 μm, preferably 0.5 to 20 μm. If the average particle size of the active material is too large or too small, it may not be uniformly dispersed in the polyether polymer.

  The content of the active material in the positive electrode film (B) is usually from 10 to 5,000 parts by weight, preferably from 30 to 2,000 parts by weight, more preferably from 50 to 100 parts by weight based on 100 parts by weight of the polyether polymer. 1,000 parts by weight. When the content of the active material in the positive electrode film is too small, the function as the positive electrode may be insufficient. On the other hand, when the content is too large, the active material may be dispersed unevenly in the positive electrode film (B).

The conductivity-imparting agent used as the constituent material of the positive electrode film (B) is a substance that assists the conductive properties of the active material, and can be used without limitation as long as it is usually used for the positive electrode of a battery. Examples of such a conductivity-imparting agent include carbon particles such as carbon black, acetylene black, ketjen black, and graphite.
The average particle diameter of the conductivity-imparting agent is usually 10 to 80 nm, preferably 20 to 50 nm. If the average particle diameter of the conductivity-imparting agent is too small, the conductive film may not be uniformly dispersed. Conversely, if the conductivity-imparting agent is too large, the cathode film may have irregularities on the surface and may be easily broken.
The conductivity-imparting agent preferably has a moderately large amount of oil absorption from the viewpoint of blending amount and conductivity, and the dibutyl phthalate (hereinafter sometimes referred to as DBP) absorption amount is usually 100 to 500 ml / g, preferably Is 150 to 400 ml / g.

  The content of the conductivity-imparting agent in the positive electrode film (B) is usually 2 to 20 parts by weight, preferably 3 to 15 parts by weight per 100 parts by weight of the active material. If the content of the conductivity-imparting agent is too small, the battery reaction of the active material cannot be effectively used and the battery capacity may be lowered. If the content is too large, the thickness of the positive electrode film is difficult to be uniform, and the battery capacity per unit weight May also decrease.

The lithium salt of the electrolyte salt compound used as the constituent material of the positive electrode film (B) is not necessarily the same as the lithium salt used as the constituent material of the electrolyte film (A), but has a high decomposition temperature and is in a powder form It is preferable that
The content of the lithium salt in the positive electrode film (B) is usually 10 to 30 parts by weight, preferably 13 to 26 parts by weight, more preferably 17 to 22 parts by weight per 100 parts by weight of the polyether polymer. If the lithium salt content of the positive electrode film (B) is too small, the ionic conductivity of the positive electrode film (B) may be reduced, and if it is too high, the mechanical strength and ionic conductivity of the positive electrode film (B) are poor. May be sufficient.

Moreover, it is preferable that a positive electrode film (B) contains the liquid compound (L) which has the above-mentioned viscosity in 25 degreeC of 100-2,000 mPa * s, and has an alkylene oxide repeating unit. Also in the positive electrode film (B), the liquid compound (L) dissolves in the polyether polymer to express the action of a plasticizer, improves the adhesion with the electrolyte film, and increases the ion mobility in the positive electrode film. Has the effect of improving. The liquid compound (L) also improves the adhesion at the interface when the current collector is laminated on the positive electrode film (B).
Content in case a positive electrode film (B) contains a liquid compound (L) is the same as content per polyether polymer in said electrolyte film (A).

In order to produce the positive electrode film (B), the polyether polymer, the active material, the conductivity-imparting agent and the lithium salt, preferably the liquid compound (L), and further used in the electrolyte as necessary. Composition containing various aprotic carbonate compounds, anti-aging agents, light stabilizers, lubricants, flame retardants, antifungal agents, antistatic agents, colorants, reinforcing materials, fillers, etc. This is formed into a film by an extruder.
The composition preparation and extrusion molding apparatus and procedure for producing the positive electrode film (B) are the same as in the case of the electrolyte film (A). By this mixing, the solid compounding agent can also be uniformly dispersed in the polyether polymer.

The temperature of the extruder kneading part for stably producing the positive electrode film (B) is usually 80 to 200 ° C, preferably 100 to 190 ° C, more preferably 110 to 180 ° C. If the temperature of the kneading part is too low, the viscosity increases and it may be difficult to smoothly extrude a thin film. Conversely, if the temperature of the kneading part is too high, the polymer undergoes thermal decomposition and the film strength decreases. there's a possibility that.
Also, as in the case of manufacturing the electrolyte film (A), a cast roll is placed in front of the take-up roll, and the thickness and tension of the film are detected and fed back to the extruder and the cooling roll to control the thickness. Is preferred. The thickness of the positive electrode film (B) controlled by a cast roll or the like is preferably 30 to 90 μm, more preferably 35 to 80 μm, and particularly preferably 40 to 75 μm. If the thickness is too thin, the film handling property (handling property) may be inferior. On the other hand, if the thickness is too thick, the adhesiveness and foldability with the laminated film in contact with the film will not be reduced, and the battery output will not be improved. There is a possibility.
By making the surface of the cooling roll into a mirror surface, the surface of the film extruded from the die can be finished more smoothly.

In the method of the present invention, the electrolyte film (A) and the positive electrode film (B) are stacked and pressure-bonded through a biaxial roll, a calender roll, a roll press or the like to obtain a lithium battery laminate. By pressure-bonding through the roller, the thickness of the laminate can be made thinner than the total thickness of both films, and the adhesion between the two films can be strengthened to realize a high output battery.
The surface temperature of the roller at the time of pressure bonding is preferably 30 to 120 ° C, more preferably 35 to 100 ° C, and particularly preferably 40 to 90 ° C. If the roller surface temperature is too low, the laminate may be peeled off and the adhesion may be insufficient. Conversely, if the roller surface temperature is too high, the film thickness will vary greatly, and the thickness will be too thin. May be reduced.

  When the electrolyte film (A) and the positive electrode film (B) are pressure-bonded with a roller, the roller gap is 1 / 1.3-1 / 1.02 of the total thickness of the electrolyte film (A) and the positive electrode film (B). , Preferably 1 / 1.25 to 1 / 1.05, more preferably 1 / 1.22 to 1 / 1.08. If the value of this ratio is too small, the laminate may be easily peeled off and adhesion may be insufficient. Conversely, if the value of the ratio is too large, the film thickness becomes thin and the uniformity of the interface is impaired. there is a possibility.

As an alternative to the above laminating method, a positive electrode current collector is previously laminated on the side of the positive electrode film (B) that does not come into contact with the electrolyte film (A) by a roller, a press or the like before the two films are pressure-bonded with a roller. Alternatively, the laminate and the electrolyte film (A) may be pressure-bonded with the roller to produce a lithium battery laminate in which the electrolyte film (A) and the positive electrode film (B) are in contact with each other. According to this method, there is an advantage that the adhesion between the positive electrode current collector and the positive electrode film is further improved. As the positive electrode current collector, an aluminum foil is preferably used. The shape of the positive electrode current collector is not particularly limited, but usually a film or sheet of about 5 to 300 μm is preferably used.
When the positive electrode film (B) is a laminate with the positive electrode current collector and / or when the electrolyte film (A) is a laminate with the negative electrode, the net of the electrolyte film (A) and the positive electrode film (B) is also obtained. It should be operated so that the ratio of the total thickness of the roller and the gap between the rollers is within the above range.

  Prior to pressure-bonding both films with a roller, a negative electrode is laminated in advance on the side of the electrolyte film (A) that does not contact the positive electrode film (B), and the laminate and the positive electrode film (B) are attached to the roller. A method of manufacturing a laminate for a lithium battery in which the electrolyte film (A) and the positive electrode film (B) are in contact with each other by pressure bonding may be employed. As the negative electrode, lithium foil is preferably used. The shape of the negative electrode is not particularly limited, but a film or sheet of about 5 to 300 μm is usually used. A film in which particles such as graphite and activated carbon are attached to a negative electrode current collector made of copper or the like as a negative electrode with a binder such as an acrylic polymer or PVDF can also be used.

  The electrolyte film (A) -positive film (B) laminate obtained by the method of the present invention has a thickness of preferably 40 to 140 μm, more preferably 50 to 120 μm, and particularly preferably 70 to 110 μm. In addition, the transport number is high and the adhesion between both films is large.

The surface of the positive electrode film (A) of the laminate for a lithium battery obtained by the method of the present invention is laminated on the positive electrode current collector, the surface of the electrolyte film (B) on the negative electrode, and the negative electrode is laminated on the negative electrode current collector. Thus, a coin-type lithium battery is formed.
A lithium battery having a laminated body for a lithium battery obtained by the method of the present invention has characteristics of expressing high output, high reliability, and easy manufacture.

Hereinafter, the present invention will be described more specifically with reference to production examples, examples and comparative examples, but the present invention is not limited thereto. “Part” is based on weight unless otherwise specified. The test and evaluation were performed according to the following methods.
(1) Film thickness before pressure bonding The center and four corners (total of 5 points) of a constituent film sample having a length of 50 mm and a width of 30 mm were measured with a digital film thickness meter, and the average value thereof was taken as the film thickness. The unit is (μm).
(2) Film thickness after pressure bonding The central portion in the length direction of the film (laminate) was measured at a digital film thickness meter every 5 mm in the width direction, and the average value thereof was taken as the thickness of the laminate. . The unit is (μm). Further, the difference between the maximum value and the minimum value of the measured values at these five points was divided by the average value to obtain thickness variation. Units(%).
(3) Deformability of support film The degree of deformation of the support film laminated on both sides of the laminate was judged visually. Judgment criteria are as follows.
○: Wrinkles and blisters are not seen in the support film, and there is no peeling with the laminate.
Δ: Some wrinkles and blisters are seen on the support film, but peeling with the laminate is not observed.
X: Wrinkles and blisters are observed on almost the entire surface, and there are many peeling spots with the laminate.

(4) Adhesion between films The support film was peeled off, the laminated interface was observed from the electrolyte film side, and the degree of transparency was visually observed to determine the adhesion. Judgment criteria are as follows. However, when there are many wrinkles and blisters on the surface of the electrolyte film, determination is impossible.
A: There is no turbidity at the interface, and a smooth positive electrode surface is observed.
○: Although the interface is slightly turbid, the positive electrode surface is observed.
X: There is no transparency at the interface, and the positive electrode surface is not observed.

(5) Battery capacity (initial capacity and variation in initial capacity)
A polypropylene gasket (outer diameter 20 mm, inner diameter 16 mm, height 3 mm) is placed on the joint surface with the cap of a stainless steel container (diameter 20 mm, height 3 mm), and then the positive electrode film is in contact with the electrolyte film. -A test piece of a positive electrode film laminate was put, a stainless steel disk and a spring were sequentially stacked, and a stainless steel cap was put on to close a coin type battery having a thickness of about 3.2 mm. The battery capacity was measured by setting the initial battery capacity after applying a predetermined charge / discharge voltage (charge / discharge voltage difference 1.5V) twice by a constant current method at 60 ° C. with a charge / discharge rate of 0.2C. It was measured. It measured about 10 coin type batteries produced using 10 test pieces per 1 test object. As the initial battery capacity, an average value of five values having larger capacities was used. The unit is [mAh / g-active material]. For the variation, a value obtained by dividing the difference between these five maximum values and minimum values by the initial battery capacity was used. Units〔%〕.

(Production Example 1) Production of polyether polymer A jacket and an autoclave equipped with a stirrer were dried and purged with nitrogen, and 65.1 parts of triisobutylaluminum, 217.9 parts of toluene and 121.6 parts of diethyl ether were charged. While the internal temperature was set at 30 ° C., 11.26 parts of phosphoric acid was added at a constant rate over 10 minutes. To this, 5 parts of triethylamine was added and aged for 2 hours at 60 ° C. to obtain a catalyst solution.
The autoclave was purged with nitrogen, and 1514 parts of n-hexane and 63.3 parts of the catalyst solution were charged. Set the internal temperature to 30 ° C, add 7.4 parts of ethylene oxide with stirring and react, then add 14.7 parts of an equimolar mixture of ethylene oxide and propylene oxide to react to form seeds did.
In the polymerization reaction liquid in which the internal temperature was set to 60 ° C. and the seed was formed, 439.6 parts (92 mol%) of ethylene oxide, 25.2 parts (4 mol%) of propylene oxide, 49.5 parts of allyl glycidyl ether (4 mol%) and a mixed solution consisting of 427.4 parts of n-hexane were continuously added at a constant rate over 5 hours. After the addition was complete, 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 anti-aging agent was added and stirred. The polymer crumb was filtered and then vacuum dried at 40 ° C. to obtain a powdery polyether polymer P.
The composition of the polyether polymer P was 91.6 mol% of ethylene oxide (EO) units, 4.7 mol% of propylene oxide (PO) units, and 3.7 mol% of allyl glycidyl ether. Moreover, Mw of this polymer was 310,000, Mw / Mn was 6.2, and the reduced viscosity was 1.1 dl / g.

Example 1
In a 25 mm diameter twin screw extruder (screw rotation speed 150 rpm, L / D = 30), 100 parts of polyether polymer P is fed to the first feed port, and electrolyte salt compound bis (trifluoromethanesulfonyl) imide is fed to the second feed port. 50 parts of lithium (manufactured by Kishida Chemical Co., Ltd.) and 1 part of 2,2-dimethoxy-1,2-diphenylethane-1-one (product name: Irgacure 651, manufactured by Ciba Specialty Chemicals) Trimethylolpropane trimethoxytripolyoxyethylene ether of liquid compound 1 (product name: TMP-30U, trimethoxylation reaction product, manufactured by Nippon Emulsifier Co., Ltd., viscosity at 25 ° C .: 420 mPa · s) 60 via a plunger pump at the third feed port The parts were fed and extruded into a film with a coat hanger die. The temperature conditions were an inlet barrel temperature of 30 ° C., a central barrel of 100 ° C., a head of 140 ° C., and a die temperature of 140 ° C. An uncrosslinked film was obtained by winding the extruded film on a take-up roll through a cast roll while sandwiching both sides with a PET support film (product name: Diafoil, manufactured by Mitsubishi Chemical Corporation, thickness: 25 μm). This film was crosslinked by irradiating with 30 mJ / cm ² of ultraviolet rays to obtain an electrolyte film. The thickness of the electrolyte film was 30 μm.

In a 25 mm diameter twin screw extruder (screw rotation speed 150 rpm, L / D = 30), 100 parts of the polyether polymer P was introduced into the first feed port, and ketjen black (product name ketjen black EC, A Henschel mixer mixture and electrolyte of 15 parts by Lion, average particle size of 35 nm, DBP absorption of 350 ml / g) and 300 parts of active material (Li _0.33 MnO ₂ , Chuo Electric Industry Co., Ltd., average particle diameter of 0.5 μm) 30 parts of the salt compound bis (trifluoromethanesulfonyl) imide lithium was supplied and extruded into a film with a coat hanger die. The temperature conditions were an inlet barrel temperature of 30 ° C., a central barrel of 160 ° C., a head of 140 ° C., and a die temperature of 140 ° C. The extruded film was wound on a take-up roll through a cast roll while sandwiching both sides with a PET support film (same as above) to obtain a positive electrode film. The thickness of the positive electrode film was 80 μm.

The electrolyte film and the positive electrode film thus obtained are first cut into strips having a length of 50 mm and a width of 30 mm, and the support film on one side is peeled off. The peeled surfaces were stacked and passed through a hot roll press device (device name COT2015H, manufactured by COSMO) to obtain an electrolyte film-positive electrode film laminate.
The gap between the rollers was adjusted with a clearance gauge and a device dial so that the roller gap would be 1 / 1.2 of the total thickness (110 μm) of the electrolyte film and the positive electrode film. The roller temperature was set to 60 ° C. The thickness of the obtained electrolyte film-positive electrode film laminate was 97 μm. Table 1 shows the results of testing and evaluating the thickness variation of the laminate, the deformability of the support film and the adhesion at the interface of the laminate, the initial battery capacity of the coin-type battery produced using the laminate, and the variation thereof.

(Examples 2-5, Comparative Examples 1-3)
The method described in Example 1 was carried out in the same manner as in Example 1 except that the liquid compound to be blended in the electrolyte film and the liquid compound to be blended in the positive electrode film were changed to the compounds and amounts shown in Table 1. An electrolyte film-positive electrode film laminate was obtained. Table 1 shows the results of the same tests and evaluations as in Example 1 for the laminate and the coin battery manufactured using the laminate.
However, in Example 2, 40 parts of trimethylolpropane trimethoxytripolyoxyethylene ether of the liquid compound 1 was further supplied to the third feed port of the extruder during the production of the positive electrode film. In Examples 3 and 4, two liquid compounds shown in Table 1 were mixed in advance and mixed from the third feed port. Example 5 has the same conditions as Example 2 except that the roller temperature was changed to 125 ° C.

(note)
* 1: 2,2-bis (4-hydroxyphenyl) propanedimethoxydipolyoxyethylene (product name: BA-6 glycol dimethoxylation product, manufactured by Nippon Emulsifier Co., Ltd., viscosity at 25 ° C., 2,300 mPa · s)
* 2: Ditridecyl phthalate (product name Vinicizer, manufactured by Kao Corporation, viscosity at 25 ° C., 300 mPa · s)
* 3: tri (methoxypolyethylene glycol) borate [12 alkylene oxide repeating units, viscosity at 25 ° C. 280 mPa · s; synthesized by a known method, for example, Y.M. Kato, et. al. , Solid State Ionic, 150, p. 355 (2002). ]
* 4: Methoxymyristin polyoxyethylene ether (product name Riquemar B-205 methoxylation product, manufactured by Riken Vitamin Co., Ltd., viscosity at 25 ° C., 40 mPa · s)

As shown in Table 1, the electrolyte film-positive electrode film laminate produced by the production method of the present invention has good adhesion, and all the lithium batteries produced using them have high variations with little variation. It had a capacity (Examples 1 to 5). In particular, Example 2 in which the prescribed liquid compound was also contained in the positive electrode film, and the liquid film 1 having the structure of the above chemical formula (3) and the liquid compound 4 having the structure of the above chemical formula (3) as the electrolyte film (* In Example 3 produced by using 3) together, the laminate had very good adhesion and exhibited high initial battery capacity battery characteristics with little variation. Further, in Example 4 in which the liquid compounds having the structures of the chemical formulas (1) and (2) were used in combination, a battery having higher capacity and improved variation was obtained compared to Example 1 in which only the liquid compound of the chemical formula (1) was used. It was.
On the other hand, in Comparative Example 1 in which the electrolyte film was prepared using the liquid compound 2 (* 1) having a too high viscosity, the adhesion was insufficient and the initial battery capacity varied greatly. When an electrolyte film was prepared using a compound having no alkylene oxide repeating unit even though the viscosity was within the specified range as liquid compound 3 (* 2), the adhesion of the laminate was good, but the initial capacity of the battery And the variation was large (Comparative Example 2). In addition, if the crimping operation is performed under conditions that deviate from the rule of the roller gap when laminating the electrolyte film and the positive electrode film, the thickness variation of the laminate and the deformation of the support film are large, and the variation of the initial battery capacity is also large. (Comparative Example 3).

Claims (10)

For a lithium battery obtained by laminating an electrolyte film (A) containing a polyether polymer and a lithium salt and a positive electrode film (B) containing a polyether polymer, an active material, a conductive agent and a lithium salt A method for producing a laminate,
The electrolyte film (A) and the positive electrode film (B) are formed by an extrusion method,
The electrolyte film (A) contains a liquid compound having an alkylene oxide repeating unit with a viscosity at 25 ° C. of 100 to 2,000 mPa · s,
(A), (B) Lithium battery characterized in that lamination of both films is performed by pressure bonding with a roller having a gap of 1 / 1.3-1 / 1.02 of the total thickness of both films. Method for manufacturing a laminated body. The method for producing a laminate for a lithium battery according to claim 1, wherein the roller has a surface temperature of 30 to 120 ° C. The method for producing a laminate for a lithium battery according to claim 1 or 2, wherein the electrolyte film (A) is obtained by adjusting a film extruded with an extruder to a thickness of 10 to 50 µm. The manufacturing method of the laminated body for lithium batteries in any one of Claims 1-3 in which the said positive electrode film (B) adjusts the film extruded with the extruder to thickness 30-90 micrometers. The method for producing a laminate for a lithium battery according to any one of claims 1 to 4, wherein the positive electrode film (B) is obtained by previously laminating a positive electrode current collector on a side not in contact with the electrolyte film (A). 6. The positive electrode film (B) further comprises a liquid compound having an alkylene oxide repeating unit having a viscosity at 25 ° C. of 100 to 2,000 mPa · s. Of manufacturing a laminate for a lithium battery. The liquid compound having an alkylene oxide repeating unit having a viscosity at 25 ° C of 100 to 2,000 mPa · s is a compound having a chemical formula represented by the following general formula (1) or (2): The manufacturing method of the laminated body for lithium batteries in any one.
(R ¹ ) (R ² ) C (CH ₂ OX) ₂ (1)
R ³ B (OX) ₂ (2)
Here, R ¹ is H, CH ₃ or CH ₂ CH ₃ , R ² is H, CH ₃ , CH ₂ CH ₃ , CH ₂ OX or OX, R ³ is OX, phenyl group, vinylphenyl group or methoxy A phenyl group, X represents (AO) _n Y, AO represents an alkylene oxide repeating unit, Y represents H, C _m H _{2m + 1} or C _m H _2m-1 , and n and m are integers of 1 to 50 It is. The lithium battery according to claim 7, further comprising a compound having a chemical formula represented by the following general formula (3) as the liquid compound having an alkylene oxide repeating unit having a viscosity at 25 ° C. of 100 to 2,000 mPa · s. Method for manufacturing a laminated body.
R ⁴ (R ⁵ ) (R ⁶ ) ZX (3)
Here, R ⁴ represents C _k H _{2k + 1} or C _k H _2k-1 , R ⁵ and R ⁶ represent H, CH ₃ , C ₂ H ₅ or OCH ₃ , Z represents COO or O, k represents It is an integer of 3-60. The method for producing a laminate for a lithium battery according to any one of claims 1 to 8, wherein the reduced viscosity of the polyether polymer that is at least a component of the electrolyte film (A) is 0.6 to 25 dl / g. The lithium battery which has the laminated body for lithium batteries obtained by the manufacturing method in any one of Claims 1-9.