JP3171238B2 - Polymer composite electrolyte membrane and secondary battery using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer composite electrolyte membrane used as an electrolyte layer of a secondary battery, a secondary battery using the same, and a method for producing the same.

[0002]

2. Description of the Related Art With the rapid expansion of the market for notebook personal computers, mobile phones, and the like, the demand for small, thin, high-output, large-capacity secondary batteries used in these computers is rapidly increasing.
Against this background, various types of highly ion-conductive solid electrolytes for realizing small, thin, and high-output secondary batteries have been studied. Examples of such an ion conductive solid electrolyte include a polymer solid electrolyte and an inorganic solid electrolyte such as an iodine complex. Among these, solid polymer electrolytes are classified into those containing no organic solvent and those containing polymer solvents.

The following conditions are important for an ion-conductive polymer electrolyte for realizing a small, thin and high-output secondary battery.
(1) Metal ions generated by ion dissociation of a metal salt are easy to move, that is, have high ionic conductivity; and (2) A self-supporting thin film can be formed, and the thin film is resistant to compression and pulling force. And sufficient resistance, that is, high mechanical strength.

As a conventional polymer solid electrolyte, a polymer having a polyether segment such as polyethylene oxide (hereinafter referred to as a PEO-based polymer) in which a metal salt is dissolved, or a PEO-based polymer is crosslinked, and a metal salt is added thereto Dissolved ones are known. US Patent No. 4,30
Japanese Patent No. 3,748 discloses a chargeable / dischargeable power generation device using, as an electrolyte, a solid solution obtained by dissolving an ionic substance in a polymer having ethylene oxide as a main chain skeleton. Also,
JP-A-8-7924 discloses an ion-conductive polymer obtained by crosslinking a PEO-based polymer with an acryloyl group or the like. However, there is a problem that these PEO-based polymers have insufficient ionic conductivity as an electrolyte of a secondary battery.

To solve this problem, a polymer gel electrolyte having improved ionic conductivity by including an organic solvent in a polymer has been studied. For example, Japanese Patent Publication No. 61-23947
The publication discloses a polymer such as polyvinylidene fluoride,
A polymer gel electrolyte comprising a Group I or Group II metal salt and an organic solvent having excellent solubility in both is disclosed. Further, for example, US Pat. No. 5,296,318 discloses a polymer gel electrolyte in which a copolymer film of 8 to 25% by weight of hexafluoropropylene and vinylidene fluoride is impregnated with an organic solvent solution containing a lithium salt. Have been.

Further, a polymer gel electrolyte using a crosslinked product of a PEO-based polymer has been studied.
No. 109310 discloses that a PEO-based polymer capable of being crosslinked, a solution capable of dissolving an alkali metal salt, and an alkali metal salt are mixed, and the molded product is irradiated with light, radiation, or the like to obtain a P.O.
There is disclosed a method of forming a complex in which a solution containing an alkali metal salt has penetrated into a cross-linked polymer by cross-linking an EO-based polymer.

Further, a polymer gel electrolyte combining two or more kinds of polymers has been studied. For example, JP-A-58-75779 discloses polyvinylidene fluoride,
Polymethyl methacrylate, at least one polymer selected from other specific polymers, and a lithium salt,
A polymer battery comprising a specific organic solvent, a metal lithium anode, and a positive electrode made of a specific inorganic compound is disclosed.

Japanese Patent Application Laid-Open No. 9-97618 discloses a polymer alloy film in which a poorly soluble polymer and a soluble polymer are mixed or made compatible with each other in an organic electrolytic solution, and the polymer alloy film is impregnated with the organic electrolytic solution to form a gel. A molecular gel electrolyte is disclosed. In this case, polyvinylidene fluoride is exemplified as the polymer that is hardly soluble in the organic electrolyte, and polyethylene oxide is exemplified as the polymer that is soluble in the organic electrolyte. However, these methods have a problem that it is impossible to stably maintain a solution in a polymer gel and to achieve high ionic conductivity.

[0009] On the other hand, there has been devised a contrivance on the material composition for improving both the mechanical strength and the ionic conductivity of the ion-conductive polymer electrolyte. For example, JP-A-63
Japanese Patent Application Laid-Open No. -102104 discloses a configuration in which an ion-conductive polymer electrolyte is filled in pores of a polymer porous membrane. JP-A-5-299119 discloses a polymer gel electrolyte in which an electrolyte solution is contained in a polymer blend having a microphase-separated structure.

Japanese Patent Application Laid-Open No. 5-325990 discloses a polymer solid electrolyte comprising a polymer serving as a matrix and a polymer containing a solution forming an ion conduction path formed in a network inside the matrix. ing. Further, JP-A-5-299119 and JP-A-5-325
Japanese Patent Application Laid-Open No. 990 describes a method in which a polymer fused body in the form of fine particles is prepared and impregnated with a metal salt solution. Even with these methods, there is a problem that it is impossible to stably maintain the solution in the polymer composite and achieve high ionic conductivity.

[0011]

As described above, any of the conventional methods cannot provide a polymer electrolyte satisfying both high ionic conductivity and mechanical strength. What has satisfied both reliability and output has not yet been known. Therefore, there is a problem that it is difficult to sufficiently cope with a demand for a smaller, thinner and higher output accompanying the progress of portable information devices, which is expected to increase further in the future.

That is, the present invention has been made in view of the conventional problems, and a polymer electrolyte which simultaneously satisfies both high ionic conductivity and good mechanical strength, and high reliability using the same. It is an object of the present invention to provide a high-output secondary battery and a simple manufacturing method thereof.

[0013]

SUMMARY OF THE INVENTION The present invention provides a polymer composite electrolyte membrane comprising a polymer obtained by curing a photocurable resin and an ion-conductive substance. The present invention relates to a polymer composite electrolyte membrane characterized in that a low portion is present and the polymer concentration changes continuously and periodically depending on the position.

Such a polymer composite electrolyte membrane can be manufactured by irradiating a mixture comprising a photocurable resin and an ion conductive substance with interference light.

The polymer composite electrolyte membrane of the present invention comprises a polymer and an ion conductive substance. "The polymer concentration is continuously changing depending on the position" means that the polymer and the ion-conductive substance are in a compatible state and the polymer and the ion-conductive substance do not have a clear boundary. That is, the polymer composite electrolyte membrane of the present invention has a clear shape even when the polymer is in the form of a gel swollen by an ion-conductive substance, or when a network structure or a porous structure of the polymer is observed. It is not possible to observe a perfect boundary.

The portion where the concentration of the polymer is high, that is,
The part of the membrane where the polymer density is high and the content of the ion conductive substance is low, and the part where the concentration of the polymer is low, that is, the part where the polymer density is low and the content of the ion conductive substance is high in the membrane are It is configured to exist periodically.

Here, a portion having a low polymer concentration serves as an ion conduction channel, and a portion having a high polymer concentration retains mechanical strength, so that high ion conductivity and good mechanical strength are obtained.

When such an electrolyte is used for a secondary battery,
Since the electrolyte has high ionic conductivity and good mechanical strength, it is difficult to short-circuit, and a high reliability and high output battery with a large charge / discharge rate can be obtained. When used, the outflow of liquid can be suppressed, and at the same time, the strength of the entire structure can be maintained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

<Polymer Composite Electrolyte Membrane> The polymer used in the polymer composite electrolyte membrane of the present invention is obtained by curing a photocurable resin. The photo-curable resin is not particularly limited as long as it can be cured by light, but it is preferable that a cross-linked structure is introduced into at least a part of the structure. preferable. Particularly, a polymer of an ultraviolet curable resin such as a polyfunctional acrylate compound is preferable from the viewpoints of effects and ease of production.

Examples of the polyfunctional acrylate compound include ethylene glycol diacrylate, 1,4-butanediol diacrylate, triethylene glycol diacrylate, neopentyl glycol diacrylate,
Bifunctional acrylates such as 1,6-hexanediol diacrylate and ethylene oxide-modified bisphenol A diacrylate and their methacrylate compounds, polyfunctional such as trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and pentaerythritol hexaacrylate Acrylates and their methacrylate compounds are included.

Used in the polymer composite electrolyte membrane of the present invention
Ion-conducting materials are caused by the movement of ionic carrier species.
There is no particular limitation as long as the substance shows electrical conductivity.
And ethylene carbonate, propylene carbonate, di
Methyl carbonate, diethyl carbonate, methyl ether
Tyl carbonate, γ-butyrolactone, N, N‘-di
Methylformamide, dimethyl sulfoxide, N-methyl
In high dielectric constant solvents such as lupyrrolidone and m-cresol, C
10_Four ^-, BF_Four ^-, PF₆ ^-, CF_ThreeSO_Three ^-, (CF_ThreeS
O_Two)_TwoN^-, (C_TwoF_FiveSO_Two)_TwoN^-, (CF_ThreeSO_Two)
_ThreeC^-, (C_TwoF_FiveSO_Two) _ThreeC^-Alkali gold of anions such as
Electrolyte salt solution in which genus salts, alkaline earth metal salts, etc. are dissolved;
A polymer electrolyte such as polyacrylic acid is used for the high dielectric constant solvent.
Dissolved polymer electrolyte solution; atactic polypropylene
Oxide, polyethylene oxide, polyamine, poly
Polymeric ion conductors such as ethyleneimine; and these
Gel ion obtained by swelling some polymer ion conductor with solvent
Conductors and the like.

The polymer composite membrane of the present invention is composed of a structure in which the concentration of the polymer changes continuously and periodically depending on the position, and is different from a separator membrane used in a conventional battery. That is, in the separator membrane, pores of several μm or more are irregularly formed in the polymer membrane, and the concentration of the polymer changes discontinuously and irregularly. In the present invention, the rate of the continuous density change is not particularly limited, and can be changed linearly or sinusoidally with respect to the position.

FIG. 1 shows an example of the polymer composite electrolyte membrane 1 of the present invention. FIG. 1A is a cross section of the film, in which the polymer-rich portions 2 and the polymer-lean portions 3 are alternately present in the form of vertical stripes. FIG. 1B is a plan view thereof, in which a polymer-rich portion 2 and a polymer-lean portion 3 are present in a stripe shape. That is, the high-molecular-weight portions are present in a state in which the plates are arranged vertically. The concentration of the polymer changes periodically in the direction perpendicular to the plate surface, but hardly changes in the direction of the plate surface. In the present application, even when the term “plate shape” is used, the concentration change between the polymer rich portion and the polymer thin portion is continuous. Further, as shown in FIGS. 7 (a) and 7 (b), the rich portion may be rod-shaped.

In the present invention, it is most preferable that the dense portion has a plate shape from the viewpoint of the effect of the present invention. As a plate-like direction,
In addition to the direction perpendicular to the film surface as shown in FIG.
May be inclined with respect to the film surface. However, if the plate-shaped thick portion becomes parallel to the film surface, the ion conductivity may decrease, so that it is preferable that the plate-like thick portion is inclined to some extent.

In the present invention, the period of the concentration change of the polymer is not particularly limited.
μm or less is preferable, and usually formed to an extent of 0.1 μm or more. In the present invention, if the polymer concentration is 50% by volume or more, particularly preferably 70% by volume or more, the strength of the polymer composite electrolyte membrane is sufficiently increased in the portion where the concentration of the polymer is the highest. Can be kept.

<Method for Producing Polymer Composite Electrolyte Membrane> In order to produce the polymer composite electrolyte membrane of the present invention, it is preferable to use a photocurable resin and polymerize it with interference light to form a polymer composite electrolyte membrane. In this case, the following two methods can be used.

First, in the first method, a mixture of a photocurable resin and an ion-conductive substance is formed into a film, and irradiated with interference light. A portion having a high polymer concentration is generated corresponding to a portion having a high light intensity of the interference light, and a portion having a low polymer concentration is generated corresponding to a portion having a strong light intensity of the interference light. In this method, the ion-conductive substance is not limited to those that do not affect photopolymerization, but any of the above-mentioned ion-conductive substances can be used. This method has the advantage that the manufacturing process is very simple.

In the second method, a mixture of a photocurable resin and a liquid compound having relatively good compatibility with the polymerized polymer is formed into a film, and irradiated with interference light. After obtaining a membrane structure having a portion having a high polymer concentration and a portion having a low polymer concentration in this manner, for example, the obtained film is immersed in an ion conductive material to replace the liquid compound with the ion conductive material. In this method, an ion conductive substance that affects photopolymerization or an ion conductive substance that is weak to light can be used.

As the photocurable resin used in the first and second methods, the above-mentioned polyfunctional acrylate compound is preferable in view of the properties of the obtained polymer composite film and the ease of production.

It is preferable to use an inert compound such as silicone oil as the liquid compound used in the second method.

In the present invention, a polymerization initiator can be added to the photocurable resin as required. Examples of the polymerization initiator include, for example, acetophenone compounds such as diethoxyacetophenone, 1-hydroxycyclohexylphenylketone-1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, benzoin, benzoin Benzoin compounds such as methyl ether and benzoin isobutyl ether; benzophenone;
Benzophenone-based compounds such as phenylbenzophenone-3,3′-dimethyl-4-methoxybenzophenone, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, thioxanthone, 2-chlorothioxanthone, Isopropylthioxanthone-2,
And thioxanthone compounds such as 4-diisopropylthioxanthone.

As a method of forming a film of a mixture of a photocurable resin and an ion conductive substance in the first method or a film of a mixture of a photocurable resin and a liquid compound in the second method, a dip coater, a spin coater Ordinary coating film forming methods such as a bar coater and a roll coater can be used.

The interference light is generated by using coherent light having coherence according to a conventional method. In particular, when interference light is formed by laser light from at least two directions, the period of the change in the concentration of the polymer can be easily reduced, so that an electrolyte membrane having high mechanical strength and high ion conductivity can be obtained.

FIG. 3 shows the principle of manufacturing a polymer composite electrolyte membrane utilizing interference by laser beams from two directions. When a layer of a mixture of a photocurable resin and an ion conductive material is irradiated with laser light from two directions,
Interference drafts occur. Polymerization and, in some cases, a cross-linking reaction proceed according to the strength, and a film in which the concentration of the polymer changes continuously and periodically depending on the position is obtained. As a result, it is possible to obtain a structure in which the high polymer concentration portions are regularly arranged in a plate shape. The distance between the polymer dense portions can be controlled by the wavelength of the incident laser light and the angle between them.

For example, a method of irradiating the first laser light from the back (back side) of the film surface and irradiating the second laser light from the front (front side) of the film surface is used.

Further, both the first laser and the second laser light may be irradiated from the front of the film surface. At this time, if the two laser beams are made symmetrical with respect to the perpendicular to the film surface, a portion where the concentration of the polymer in the film is high can be formed in a plate shape and perpendicular to the film surface. . By doing so, the direction of ion conduction becomes perpendicular to the membrane surface, and a polymer composite electrolyte membrane having high ion conductivity can be obtained. At this time, the angle between the two laser beams is 90 to 270.
° is preferable because a polymer composite electrolyte membrane having high membrane strength can be obtained.

The type of laser light used in this manufacturing method is not particularly limited, and gas lasers such as YAG laser and ruby laser, gas lasers such as He-Ne laser, carbon dioxide laser, Kr-F excimer laser, A
From general lasers such as excimer lasers such as r-F excimer lasers, semiconductor lasers and dye lasers,
A laser having a wavelength suitable for photopolymerization is selected and used.

Further, an electron beam or the like can be used for producing the polymer composite electrolyte membrane of the present invention, but the use of interference light is more suitable for producing a large-area membrane.

<Secondary Battery> When the polymer composite electrolyte membrane of the present invention is used as an electrolyte of a secondary battery, the electrolyte has high ionic conductivity and mechanical strength. And a high output battery having a large

In the secondary battery of the present invention, for example, as shown in FIG. 2, the polymer composite electrolyte membrane 1 of the present invention is sandwiched between the positive electrode active material layer 4 and the negative electrode active material layer 5, and the positive electrode active material layer 4 is further placed thereon. The current collector 6 is sandwiched between the negative electrode current collector 7, and the surroundings are sealed by a sealant 8.

The positive electrode active material is not particularly limited as long as it absorbs positive ions or discharges negative ions at the time of discharge. LiMnO ₂ , LiMn ₂ O ₄ , LiMn ₂
Metal oxides such as CoO ₂ and LiNiO ₂ , conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, and polyparaphenylene and derivatives thereof, and a general formula (R-Sm) n (R is an aliphatic hydrocarbon residue Or an aromatic hydrocarbon residue, S represents sulfur, m, n
Is an integer of m ≧ 1 and n ≧ 1. ) (Dithioglycol, 2,5-dimercapto-1,3,4-thiadiazole, S-triazine-)
Any known positive electrode active material such as 2,4,6-trithiol) can be used.

In the present invention, the positive electrode active material can be formed by mixing with a suitable binder or a functional material. These binders and functional materials include, for example, halogen-containing polymers such as polyvinylidene fluoride as binders, and conductive materials such as acetylene black, polypyrrole, and polyaniline as functional materials to secure electronic conductivity. Examples include a conductive polymer, an organic electrolyte solution for ensuring ionic conductivity, a polymer electrolyte, and a composite thereof.

The negative electrode active material is not particularly limited as long as it is a material capable of occluding and releasing cations. Crystalline carbon such as graphitized carbon obtained by heat-treating natural graphite, coal or petroleum pitch at a high temperature, Known negative electrode active materials such as amorphous carbon obtained by heat-treating coal, petroleum pitch coke, and acetylene pitch coke, and lithium alloys such as metallic lithium and AlLi can be used.

As the positive electrode current collector and the negative electrode current collector, conventionally used thin films, meshes, and other sheets of stainless steel, copper, nickel, aluminum, and the like can be used.

Examples of the mounting form of the secondary battery of the present invention include a cylindrical type, a square type, a sheet type, and a coin type secondary battery, but are not limited to these. In the present invention, a conventionally used separator can be used separately from the polymer composite membrane.

<Method of Manufacturing Secondary Battery> In such a secondary battery using the polymer composite electrolyte membrane of the present invention, a polymer composite electrolyte membrane is separately formed on a glass substrate or the like by the above-described method. The peeled film is stacked on top of the positive electrode active material layer or the negative electrode active material layer, and a negative electrode active material layer or a positive electrode active material layer is formed thereon, or a separately formed negative electrode active material layer or It can be manufactured by being overlapped with facing the positive electrode active material layer.

Alternatively, after the mixture of the photocurable resin and the ion conductive material is applied on the positive electrode active material layer or the negative electrode active material layer as described above, the polymer composite electrolyte membrane is irradiated with interference light to form a polymer composite electrolyte membrane. It can also be formed.

The positive electrode active material layer and the negative electrode active material layer are formed by dissolving and dispersing the constituent materials in an appropriate solvent, coating the material on the positive electrode current collector, the negative electrode current collector, or the polymer composite electrolyte membrane.
It can be obtained by evaporating the solvent.

In the method of manufacturing a secondary battery according to the present invention, a conventional separator can be interposed in addition to the polymer film.

The polymer composite electrolyte membrane of the present invention can be used as an electrolyte membrane and separator for primary batteries, electric double layer capacitors, and electrolytic capacitors, in addition to secondary batteries.

[0051]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Example 1) Silicon oil 20 in 10 g of ethylene glycol diacrylate as a photocurable resin
g, and 1.5 g of camphorquinone containing an amine-based dye sensitizer was further added. The mixture was stirred at 70 ° C. under light shielding to prepare a mixed solution. This mixed solution was dropped on a glass substrate, and a film was formed by a spin coating method.

An irradiation intensity of 100 mW /
cm ^2, an Ar ion laser with a wavelength of 488nm divided by the beam splitter, the first laser beam 11 from a direction perpendicular to the substrate bottom surface, as shown in FIG. 3, and 45 ° second with respect to the perpendicular from the substrate surface Laser light 12
Irradiated for 0 seconds. As a result, a composite film of a polymer and silicon oil having a plate-like portion having a high polymer concentration corresponding to the interference fringes 13 was obtained.

Next, this substrate was immersed in a propylene carbonate solution containing lithium borofluoride at a concentration of 1 M (mol / liter) for 10 minutes to exchange the silicon oil and the propylene carbonate solution.

The obtained polymer composite electrolyte membrane had a thickness of 45 μm.
m exhibited a green color. To study the membrane structure,
About 0.5μ when dried and observed with a scanning electron microscope
Plate-like structures at m intervals were observed. The direction of the plate-like structure composed of the polymer-rich portion was about 30 ° relative to the film surface. The change in weight before and after drying indicated that the obtained polymer composite film contained a 40% by weight solution.

The polymer composite electrolyte membrane prepared as described above is sandwiched between two mirror-polished platinum blocking electrodes having a diameter of 10 mm, and the lead wire from the electrode is connected to an electrochemical work station (CH Instrument).
nts, Model 604).
When the ionic conductivity was measured at a frequency of 1 Hz to 100 kHz and a voltage of 0.1 V, it was 1.4 mS / cm at room temperature.

No outflow of the liquid from the polymer composite membrane was observed, and a tensile test showed that the breaking strength was 16 M (mega) N / m ² .

Next, a secondary battery having the structure shown in FIG. 2 was manufactured using the polymer composite electrolyte membrane thus manufactured.

First, lithium cobalt oxide having an average particle size of 5 μm, acetylene black, polyvinylidene fluoride, N-
Methyl-2-pyrrolidone was mixed and dispersed at a weight ratio of 10: 1: 1: 30. This was uniformly coated on one side of an aluminum foil serving as a positive electrode current collector using a wire bar, and dried under vacuum at 100 ° C. for 2 hours to remove the solvent. The obtained thin layer was cut into an appropriate size and cut to about 25 mAh.
The positive electrode layer having a capacity of was prepared.

On the positive electrode layer, a propylene carbonate solution containing lithium borofluoride produced as described above and a polymer composite electrolyte membrane made of an acrylic polymer were laminated.

The laminated film is made of polyvinylidene fluoride, N-
A slurry in which methyl-2-pyrrolidone, petroleum petroleum coke, and acetylene black were mixed at a weight ratio of 1: 30: 20: 1 was cast, uniformly formed by a wire bar method, and vacuum-dried at 100 ° C. for 2 hours. Thus, a negative electrode layer was obtained.

Thereafter, a stainless steel foil having the same area as the aluminum foil of the positive electrode is placed as a current collector on the negative electrode layer, and is placed on the outer peripheral portion thereof in a positional relationship shown in FIG. Hot melt adhesive was filled. Finally, the whole was heated to complete a secondary battery in which the outer peripheral edge of the current collector was covered with a hot melt adhesive.

When a charging / discharging test was performed on the obtained secondary battery, the maximum discharge current was 80 mA. When the charge / discharge test was repeated 100 times at a constant current of 5 mA between a voltage of 4.1 V and 2.0 V, the capacity, the energy density, and the maximum discharge current hardly changed.

(Comparative Example 1) In Example 1, an ultraviolet irradiation intensity of 15 mW / c was used instead of the Ar ion laser.
Example 1 was repeated except that irradiation was performed for 10 seconds using a high-pressure mercury lamp having a wavelength of 365 nm and a wavelength of 365 nm to produce a polymer composite electrolyte membrane.

In observation with a scanning electron microscope, the diameter was 200 nm.
A porous polymer thin film having a structure in which fine particles were connected in a chain was observed. In this polymer composite film, no regular change in the polymer concentration was observed, and a network structure in which particles were connected throughout the film was observed. The change in weight before and after drying indicated that the obtained polymer composite film contained a 40% by weight solution.

Table 1 shows the film thickness, tensile strength and ionic conductivity of the polymer composite electrolyte membrane and the characteristics of a secondary battery produced in the same manner as in Example 1 using this polymer composite electrolyte membrane.

No outflow of liquid from the polymer composite electrolyte membrane was observed, but from Table 1, the ion conductivity was clearly low, and the repetition durability of the secondary battery was poor.

Example 2 20 g of benzonitrile containing 1 M lithium borofluoride was added to 10 g of ethylene glycol diacrylate as a photocurable resin, and further, camphorquinone 1.5 containing an amine dye sensitizer was added.
g was added and the mixture was stirred at 70 ° C. under light shielding to prepare a mixed solution. This mixed solution was dropped on a glass substrate, and a film was formed by a spin coating method.

After that, irradiation with interference light was performed in the same manner as in Example 1 to obtain a polymer composite electrolyte membrane. In this embodiment, the replacement with the ion conductive material is unnecessary.

The resulting polymer composite film exhibited a green color. Scanning electron microscope observation showed a plate-like structure at intervals of about 0.5 μm. The direction of the plate-like structure composed of the polymer-rich portion was about 30 ° relative to the film surface. The change in weight before and after drying indicated that the obtained polymer composite film contained a 45% by weight solution.

Table 1 shows the thickness, tensile strength and ionic conductivity of the polymer composite electrolyte membrane, and the characteristics of the secondary battery manufactured in the same manner as in Example 1 using this polymer composite electrolyte membrane.

Example 3 In Example 2, the concentration was 1M.
Instead of benzonitrile containing lithium borofluoride,
Example 2 was repeated except that a 10000 molecular weight polypropylene oxide containing 1M lithium borofluoride was used.

As a result, a composite film comprising a polymer having a plate-shaped polymer-rich portion and a polypropylene oxide containing lithium borofluoride was obtained.

Table 1 shows the thickness of the polymer composite electrolyte membrane, the tensile strength, the ionic conductivity, and the characteristics of the secondary battery manufactured in the same manner as in Example 1 using this polymer composite electrolyte membrane.

(Example 4) Example 2 was repeated except that in place of ethylene glycol diacrylate, a fluorinated acrylic resin Optodyne UV3000 (manufactured by Daikin Kasei Kogyo) was used instead of ethylene glycol diacrylate.

As a result, a composite film comprising a polymer having a plate-shaped polymer-rich portion and benzonitrile containing lithium borofluoride was obtained. The obtained polymer composite film exhibited a green color. About 0.5μ in scanning electron microscope observation
Plate-like structures at m intervals were observed. The direction of the plate-like structure composed of the polymer-rich portion was about 30 ° relative to the film surface. The change in weight before and after drying indicated that the obtained polymer composite film contained a 46% by weight solution.

Table 1 shows the thickness of the polymer composite electrolyte membrane, the tensile strength, the ionic conductivity, and the characteristics of the secondary battery manufactured using this polymer composite electrolyte membrane in the same manner as in Example 1.

(Examples 5 to 7) In Example 2, the irradiation directions of the two Ar ion lasers are shown in FIGS. 4 (Example 5), FIG. 5 (Example 6), and FIG. 6 (Example 7). In this manner, irradiation was performed for 10 minutes while changing the angles so as to be 90 ° (Example 5), 120 ° (Example 6), and 150 ° (Example 7) symmetrically with respect to the perpendicular of the film surface.

As a result, a polymer composite electrolyte membrane having a plate-like polymer dense portion was obtained. Scanning electron microscope observation showed a plate-like structure at intervals of about 0.5 μm. The direction of the plate-like structure composed of the polymer-rich portion was about 90 ° with respect to the film surface. The change in weight before and after drying indicated that the obtained polymer composite film contained a 40% by weight solution.

Table 1 shows the thickness of the polymer composite electrolyte membrane, the tensile strength, the ionic conductivity, and the characteristics of the secondary battery manufactured using this polymer composite electrolyte membrane in the same manner as in Example 1.

(Example 8) A secondary battery having an electrolyte made of a composite membrane comprising a polymer having a plate-shaped polymer-rich portion obtained in Example 2 and a benzonitrile solution containing 1M lithium borofluoride was prepared. did. First, a positive electrode layer was prepared in the same manner as in Example 1, and a polymer composite electrolyte membrane was further laminated on the positive electrode layer. A metal lithium foil having the same area as the positive electrode layer was laminated on this laminated film to form a negative electrode layer. Thereafter, a stainless steel foil having the same area as the aluminum foil of the positive electrode was placed on the negative electrode layer as a current collector. Thereafter, a secondary battery was completed in the same manner as in Example 1.

Table 1 shows the characteristics of this secondary battery.

[0083]

[Table 1] In the table, the capacity after 100 charge / discharge cycles was measured in the same manner as in Example 1, and ○ indicates that there was almost no change.

[0084]

According to the present invention, it is possible to provide a polymer composite electrolyte membrane which simultaneously satisfies both high ionic conductivity and good mechanical strength. Therefore, a secondary battery using this has high reliability and high performance with high output.

Further, according to the present invention, such a polymer composite electrolyte membrane and a secondary battery can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing one example of a polymer composite electrolyte membrane of the present invention. (A) sectional view (b) plan view

FIG. 2 is a cross-sectional view showing one example of a configuration of a secondary battery of the present invention.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing a polymer composite electrolyte membrane using interference by lasers from two directions.

FIG. 4 is a cross-sectional view illustrating a method for manufacturing a polymer composite electrolyte membrane utilizing interference by laser beams from two directions at 90 °.

FIG. 5 is a cross-sectional view showing a method for manufacturing a polymer composite electrolyte membrane utilizing interference by lasers from two directions at 120 °.

FIG. 6 is a cross-sectional view showing a method for producing a polymer composite electrolyte membrane utilizing interference by lasers from two directions at 150 °.

FIG. 7 is a view showing one example of a polymer composite electrolyte membrane of the present invention. (A) Cross-sectional view (b) Plan view

FIG. 8 is a cross-sectional view showing one example of the polymer composite electrolyte membrane of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 polymer composite film 2 polymer rich portion 3 polymer dilute portion 4 positive electrode active material 5 negative electrode active material 6 positive electrode current collector 7 negative electrode current collector 8 sealant 11 first laser beam 12 second laser beam 13 Interference draft

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kosuke Amano 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation (72) Inventor Hiroshi Sakauchi 5-7-1 Shiba, Minato-ku, Tokyo NEC (56) References JP-A-6-223877 (JP, A) JP-A-8-255614 (JP, A) JP-A-8-295711 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01M 10/40 C08L 1/00-101/14 H01B 1/06

Claims (19)

(57) [Claims] 1. A polymer composite electrolyte membrane comprising a polymer obtained by curing a photocurable resin and an ion conductive material,
A polymer composite electrolyte membrane, wherein a high polymer concentration portion and a low polymer concentration portion exist in the membrane, and the polymer concentration changes continuously and periodically depending on the position. 2. The polymer composite electrolyte membrane according to claim 1, wherein a portion having a high polymer concentration exists in a plate shape in the membrane. 3. The polymer composite electrolyte membrane according to claim 1, wherein the photocurable resin is a polyfunctional acrylate compound. 4. The polymer composite electrolyte membrane according to claim 1, wherein the period of the concentration change of the polymer is 2 μm or less. 5. The method for producing a polymer composite electrolyte membrane according to claim 1, wherein a mixture comprising a photocurable resin and an ion conductive material is irradiated with interference light. 6. The polymer composite electrolyte membrane according to claim 1, wherein after irradiating the mixture comprising the photocurable resin and the liquid compound with interference light, the liquid compound is replaced with an ion conductive substance. Manufacturing method. 7. The method for producing a polymer composite electrolyte membrane according to claim 5, wherein the interference light is formed by laser light from at least two directions. 8. The method for producing a polymer composite electrolyte membrane according to claim 7, wherein the interference light is formed by a first laser light from behind the irradiation film surface and a second laser light from the front. 9. The interference light is formed by a first laser beam from the front of the irradiation film surface and a second laser beam from the front, and the angle between the first and second laser beams is 90. The method for producing a polymer composite electrolyte membrane according to claim 7, wherein the angle is from -270 °. 10. The method for producing a polymer composite electrolyte membrane according to claim 5, wherein the photocurable resin is a polyfunctional acrylate compound. 11. A secondary battery comprising a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, wherein the polymer composite electrolyte membrane according to claim 1 is used as the electrolyte layer. Secondary battery. 12. A method for manufacturing a secondary battery comprising a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer.
10. Production of a secondary battery having a step of separately producing a polymer composite electrolyte membrane by the method according to any one of 10 and a step of sandwiching the obtained polymer composite electrolyte membrane between a positive electrode active material layer and a negative electrode active material layer Method. 13. A method for manufacturing a secondary battery including a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, wherein the positive electrode active material layer or the negative electrode active material layer is formed after forming the positive electrode active material layer or the negative electrode active material layer. A polymer composite electrolyte membrane separately manufactured by the method according to any one of claims 5 to 10, which is superposed on the surface of the layer, and then a negative electrode active material layer or a cathode which forms a pair on the surface of the polymer composite electrolyte membrane A method for manufacturing a secondary battery, comprising forming an active material layer. 14. A method for manufacturing a secondary battery including a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, wherein the positive electrode active material layer or the negative electrode active material layer is formed after forming the positive electrode active material layer or the negative electrode active material layer. After applying a mixture of a photo-curable resin and an ion conductive material to the surface of the layer, the surface is irradiated with interference light to form a polymer composite electrolyte membrane, which is separately formed on the polymer composite electrolyte membrane surface The secondary anode is characterized in that a paired negative electrode active material layer or a positive electrode active material layer is overlapped, or a paired negative electrode active material layer or a positive electrode active material layer is formed on the surface of the polymer composite electrolyte membrane. Battery
Construction method . 15. The polymer composite electrolyte membrane according to claim 1, wherein the polymer composite electrolyte membrane is used between a positive electrode active material layer and a negative electrode active material layer of a secondary battery. 16. A plate-shaped portion having high mechanical strength and a portion having high ion conductivity are continuously and alternately provided, and the plate-like direction is inclined with respect to the film surface. Polymer composite electrolyte membrane. 17. The plate-shaped portion having high mechanical strength,
17. The polymer composite electrolyte membrane according to claim 16, wherein the portions having high ion conductivity are periodically arranged. 18. The polymer composite electrolyte membrane contains a polymer obtained by curing a photocurable resin and an ion conductive substance,
18. The polymer composite electrolyte membrane according to claim 16, wherein the polymer concentration is high in the plate-like portion having high mechanical strength, and the polymer concentration is low in the portion having high ion conductivity. 19. A secondary battery comprising a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, wherein the polymer composite electrolyte membrane according to claim 16 is used as the electrolyte layer. Secondary battery.