JP2001006741A - Unit cell element, and layer-built cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To laminate and form a unit cell element of a layer-built cell of a high capacity, superior battery performance of rate characteristics and cycle characteristics, and satisfactory safety and productivity at high productivity. SOLUTION: In this unit cell element 11, a conductive positive electrode base material 12, a positive electrode 13 as a first electrode, a porous film 14, a negative electrode 15 as a second electrode, and a conductive negative electrode base material 16 are layered in this order in a tabular form. The conductive positive electrode base material 12, the positive electrode 13, the porous film 14, the negative electrode 15, and the conductive negative electrode base material 16 are roughly rectangular, respectively, and the unit cell element 11 is also rectangular as a whole. A part or all of an outer edge part of the unit cell element 11 is composed of at least a part of the negative electrode 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat unit battery element having a non-fluidized electrolyte, and a stacked battery having the stacked body.

[0002]

2. Description of the Related Art A lithium secondary battery using a non-fluidized electrolyte, for example, an electrolyte obtained by forming a non-aqueous electrolyte solution into a matrix with a polymer, has a higher ion conductivity than a conventional lithium secondary battery using a mere electrolyte solution. While maintaining the properties such as conductivity, the danger of liquid leakage and ignition can be prevented. Also,
Since the safety is enhanced in this way, it is not necessary to store the battery in a metal case as in a conventional battery, and as a result, it is possible to make a sheet-like thin film. Therefore, it is extremely useful as a power source for a portable electronic device that requires reduction in size and weight.

FIGS. 4, 5, and 6 are a schematic perspective view, a top view, and a front view showing a conventional example of a unit cell element on a flat plate using a non-fluid electrolyte. Unit battery element 21
Is a conductive positive electrode base material 22, a positive electrode 23, and a porous film 24.
, The negative electrode 25 and the conductive negative electrode substrate 26 are laminated in this order in a flat plate shape. Inside the porous film 24, there is a non-fluid electrolyte in which an electrolyte is held by a polymer. In addition, the conductive positive electrode substrate 22 and the conductive negative electrode substrate 2
6 (which may be collectively referred to as a conductive electrode base material), tabs 27 and 28 are respectively extended, one end of the lead is connected to these tabs, and the other end of the lead is connected to the unit battery. It is guided outside the element.

In the above-described unit battery element having a flat plate shape, the size of the porous film 24 is usually larger than that of the positive electrode 23 or the negative electrode 25 in order to prevent a short circuit between the electrodes. That is, as is apparent from the top view corresponding to FIG. 2, the outer edge portion 31 of the unit battery element 21 (shown by a thick line in the figure)
Are all coincident with the outer edges of the porous film 24. Further, for example, in the case of a lithium secondary battery, it is usual to make the negative electrode larger than the positive electrode in order to prevent the generation of lithium dendrite. That is, as shown in FIGS. 4 to 6, the outer edge of the negative electrode 25 is disposed outside the outer edge of the positive electrode 23, and the outer edge of the porous film extends further outward than the outer edge of the negative electrode 23.

[0005]

In order to increase the capacity of a flat battery, it is conceivable to increase the thickness of the electrodes. However, in this case, the rate characteristics and the like are likely to deteriorate. Stacking in the direction is a practical method.

In order to stack the unit battery elements in the thickness direction, a predetermined number of the unit battery elements are stacked at a high speed while accurately positioning the unit battery elements in the horizontal direction, and then these unit battery elements are adhered in the thickness direction. Need to be done.

However, it is difficult to accurately position the conventional flat unit cell elements as described above during lamination. This is because the conventional unit cell element has a low rigidity because its outer edge is formed of a porous film, and it is difficult to use this portion as a positioning portion serving as a reference for positioning. Also, if the porous membrane forms the outer edge of the unit cell element, when this portion comes into contact with the device for lamination, the non-fluid electrolyte in the porous membrane falls off and adheres to the device, causing It also results in a decrease in performance.

For example, as a method of laminating, when a unit having a guide frame corresponding to the size of the unit battery element is used, and the unit battery elements are sequentially loaded along the guide frame to perform the lamination, a porous film is formed. When the outer edges are formed, the rigidity of the porous membrane is insufficient, so that even if the unit battery elements are put into the guide frame, they are not always stacked at an accurate position. Also, when the porous film forming the outer edge of the unit cell element comes into contact with the guide frame or the like at the time of introduction into the guide frame, the non-fluid electrolyte in the porous film detaches and becomes fragments, and adheres to each part. It can be lost. Further, the porous membrane may be caught by the guide frame, and the unit battery elements may not be properly stacked. In this case, if the next unit battery element is stacked as it is or a pressure for adhesion is applied, the unit battery element itself may be broken.

As a countermeasure, it is conceivable to give a certain amount of allowance (play) to the size at the time of stacking or storing it in a case after the stacking. This requires more play than necessary, which leads to a reduction in volume capacity.

The present invention has been made in view of the above circumstances, and improves productivity and battery performance of a flat-plate laminated battery in which the use of a non-fluidized electrolyte suppresses problems such as liquid leakage. The purpose is to let them.

[0011]

According to the present invention, there is provided a unit battery element having a structure in which a porous film does not protrude from an electrode having a larger area in at least a part thereof, and uses the part as a positioning portion. Thus, unnecessary contact during stacking of the unit battery elements is prevented.

That is, the unit battery element of the present invention (claim 1) comprises a first electrode, a second electrode, and a first electrode and a second electrode.
A unit cell element having a porous membrane and a non-fluid electrolyte disposed between the first electrode and / or the second electrode. The second electrode is formed at the outer edge of the second electrode.

According to a second aspect of the present invention, the unit battery element is formed in a substantially rectangular shape, and at least a part of an outer edge of the unit battery element is formed on at least a part of two opposing sides thereof with the first electrode and / or the second electrode. , More accurate positioning becomes possible.

According to a third aspect of the present invention, there is provided a unit battery element comprising: a first electrode; a second electrode; a porous film disposed between the first electrode and the second electrode; In a flat unit battery element having a fluid electrolyte, at least a part of the outer edge of the porous membrane overlaps or is located inside the outer edge of the second electrode, and The first electrode extends outside the outer edge of the first electrode.

With such a configuration, not only can the positioning at the time of lamination be performed accurately, but also it is possible to effectively prevent the occurrence of a short circuit in the battery.

According to the present invention, if the second electrode corresponds to the negative electrode, generation of dendrite can be effectively prevented.

Further, according to a fifth aspect of the present invention, in the configuration of the third or fourth aspect, the first electrode, the second electrode, and the porous film each have a substantially rectangular shape, and at least two opposing surfaces of the porous film are formed. In the side, at least a part of the outer edge of the porous membrane overlaps or is located inside the outer edge of the second electrode, and extends outside the outer edge of the first electrode. By doing so, more accurate positioning can be performed.

In the above configuration, when a conductive electrode base material (current collector) is provided on the back surface of at least one of the first and second electrodes, the electrodes are reinforced by the current collector, and thus positioning is performed. It becomes easier (claim 6). Also,
Such an effect is particularly remarkable when the thickness of the porous film is 20 μm or less (claim 8).

When the outer periphery of the current collector and the outer periphery of the electrode are made to coincide with each other, at least a part of the outermost periphery of the unit cell element is constituted by a highly rigid portion composed of the electrode and the current collector. This is extremely advantageous for a positioning method using a mechanical method and a lamination method using a jig.

The stacked battery of the present invention is obtained by stacking a plurality of such unit battery elements in the thickness direction and storing them in a case.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, the term “electrode” refers to a portion where a positive electrode or a negative electrode active material is present, and the outer edge refers to an outer peripheral edge of an electrode region when viewed from the laminating direction. is there.

FIGS. 1, 2 and 3 are a schematic perspective view, a front view and a top view, respectively, showing an example of the configuration of the unit cell element of the present invention.

The unit cell element 11 is made of a conductive positive electrode base material 12.
A positive electrode 13 as a first electrode, a porous film 14,
A negative electrode 15 as a second electrode and a conductive negative electrode base material 16 are laminated in this order in a flat plate shape.

The positive electrode 13 has a positive electrode active material and a non-fluid electrolyte obtained by making the electrolytic solution non-fluid with a polymer.
2 is provided over the entire back surface. Negative electrode 15
Has a negative electrode active material and a non-fluid electrolyte, and a conductive negative electrode substrate 16 made of metal copper or the like is provided over the entire back surface. Between the positive electrode 13 and the negative electrode 15,
A porous membrane 14 made of polyethylene or the like is provided, and a non-fluid electrolyte exists in the void.

The conductive positive electrode substrate 12 and the conductive negative electrode substrate 16
, Tabs 17 and 18 are respectively extended,
One end of a lead (not shown) is connected to each tab, and the other end of each lead is guided outside the unit cell element.

To prevent dendrite generation, the positive electrode 1
The size of the positive electrode 13 is smaller than the size of the negative electrode 15 so that the outer edge of the negative electrode 3 is disposed inside the outer edge of the negative electrode 16.

The conductive positive electrode substrate 12, the positive electrode 13, the porous film 14, the negative electrode 15, and the conductive negative electrode substrate 16 each have a substantially rectangular shape, and the unit battery element 11 as a whole has a substantially rectangular shape. It has a shape.

In FIGS. 1, 2 and 3, the entire outer edge 61 of the unit cell element (the portion indicated by a thick line in FIG. 3) is constituted by the outer edge of the negative electrode. In addition, as shown in FIGS.
The outer edge of the porous film 14 and the outer edge of the negative electrode 15 may coincide over the entire circumference, or may partially coincide. Note that, in this embodiment, the entire outer edge of the porous film 14 overlaps with the outer edges of the negative electrode 15 and the conductive negative electrode base material 16, and the outer edge of the positive electrode recedes inward from these outer edges. are doing.

In the unit battery element 11 configured as described above, the entire outer edge portion of the unit battery element 11 has rigidity, so that positioning during stacking is easy and the non-fluid electrolyte falls off. Is also less likely to occur. In addition, short circuit and dendrite generation can be prevented.

FIGS. 7 to 11 are a schematic perspective view, a front view, a right side view, a left side view and a top view showing another example of the configuration of the unit cell element of the present invention.

The unit battery element 71 includes a conductive positive electrode base material 72.
A positive electrode 73 as a first electrode, a porous film 74,
A negative electrode 75 as a second electrode and a conductive negative electrode substrate 76 are laminated in this order in a flat plate shape.

The positive electrode 73 has a positive electrode active material and a non-fluid electrolyte, and a conductive positive electrode substrate 72 made of a metal such as aluminum is provided on the entire back surface. The negative electrode 75 has a negative electrode active material and a non-fluid electrolyte, and a conductive negative electrode substrate 76 made of metal copper or the like is provided over the entire back surface. Positive electrode 73 and negative electrode 75
A porous membrane 74 made of polyethylene or the like is provided between the two, and a non-fluid electrolyte exists in the void. The conductive positive electrode substrate 72 and the conductive negative electrode substrate 76 include
Tabs 77 and 78 extend, respectively, and leads (not shown) are connected to these tabs.

To prevent dendrite generation, the positive electrode 7
The size of the positive electrode 73 is smaller than the size of the negative electrode 75 so that the outer edge of the negative electrode 75 is located inside the outer edge of the negative electrode 76. The conductive positive electrode substrate 72, the positive electrode 73, the porous film 74, the negative electrode 75, and the conductive negative electrode substrate 76 each have a substantially rectangular shape, and the unit battery element 71 also has a substantially rectangular shape as a whole. are doing.

In FIGS. 7 to 11, most of the outer edge portion 111 (shown by a bold line in FIG. 11) of the unit cell element 71 is constituted only by the outer edge of the porous film 74. In 112 to 115, the negative electrode 75
Is also constituted by the outer edge portion. That is, FIGS.
, The porous film 74 is formed at the corners 112 to 115.
And the outer edge of the negative electrode 75 overlap.

Also in the unit battery element 71 thus configured, the entire outer edge of the unit battery element 71 has rigidity, so that positioning during stacking is easy, and non-fluid electrolyte may fall off. It becomes difficult. In addition, short circuit and dendrite generation can be prevented.

In each of the above embodiments, the outer edge of the porous film overlaps the outer edge of the negative electrode on the two sides adjacent to the extended side of the tab, so that the unit battery element The outer edge is constituted by the outer edge of the negative electrode. As a result, the two sides can be used as positioning portions for easy positioning during lamination. Further, in the above embodiments, the outer edge of the porous membrane overlaps the outer edge of the negative electrode even on the side opposite to the extended side of the tab, so that the outer edge of the unit cell element is Since the outer peripheral portion of the negative electrode is used, this portion can also be used as a positioning portion, so that the battery element can be positioned more accurately.

In the above-mentioned unit cell element, the outer edge of the porous film overlaps the outer edge of the negative electrode in a part thereof, and the laminate of the negative electrode and the porous film forms a large-sized porous material on the electrode. It can be easily manufactured by mounting a membrane film and then cutting the porous membrane film so as to match the size of the electrode.

The outer edge of the negative electrode may partially extend (project) from the outer edge of the porous film. However, from the viewpoint of battery capacity, the outer edge of the porous film partially extends from the outer edge of the negative electrode. It preferably overlaps the part. When making the outer edge of the porous film smaller than the outer edge of the negative electrode in a part, it is sufficient to make the inside of the porous film about the thickness of the porous film, which is preferable from the viewpoint of battery capacity.

In each of the above embodiments, the conductive electrode base material is provided over the entire back surface of the electrode. In particular, in the portion where the outer edge of the unit cell element is constituted by the electrode, When the conductive electrode base material is provided on the back surface, the electrodes are further reinforced, so not only the positioning is further facilitated, but also the risk of part of the electrodes being detached during lamination is reduced. preferable. From the viewpoint of battery performance, a conductive electrode substrate is provided over the entire back surface of each of the positive electrode and the negative electrode. Note that electrodes may be provided on both surfaces of the conductive electrode base material.

The positive electrode and the negative electrode used in the present invention,
There are no restrictions on the non-fluidized electrolyte, the type of porous membrane, and the formation method, and materials used for ordinary batteries,
Techniques are available.

In the following, materials and techniques that can be preferably used are illustrated, particularly taking a lithium battery as an example, but the gist of the present invention is not limited thereto.

As the active material, Fe was used as the positive electrode active material,
Transition metal oxides of transition metals such as Co, Ni, and Mn, composite oxides of lithium and transition metals, transition metal sulfides, and organic compounds can be used. Specifically, MnO, V ₂ O ₅ ,
Examples include transition metal oxide powders such as V ₆ O ₁₃ and TiO ₂ , composite oxide powders of lithium and transition metals such as lithium nickelate and lithium cobalt oxide, and transition metal sulfide powders such as TiS ₂ and FeS. Examples of the organic compound include a conductive polymer such as polyaniline. Further, an inorganic compound, an organic compound and the like may be mixed and used.
Among these, a composite oxide of manganese, nickel or cobalt with lithium is preferable. The particle size of the active material in the form of particles may be appropriately selected in consideration of other components of the battery, but is usually 1 to 30 μm, particularly 1 μm.
By setting the thickness to 10 μm, battery characteristics such as a rate characteristic and a cycle characteristic are improved.

As the negative electrode material, lithium metal, another lithium alloy, graphite, coke, or the like can be used. Among these, carbonaceous materials such as graphite and coke are preferred. The particle size of the active material of the granular negative electrode may be appropriately selected in consideration of the other components of the battery, but is usually 1 to 50 μm, particularly 15 to 3 μm.
By setting the thickness to 0 μm, battery characteristics such as initial efficiency, rate characteristics, and cycle characteristics are improved.

A binder can be used to fix the active material to the electrode. In this case, any binder can be used as long as it is stable to the active material, the electrolyte, the battery reaction, the production process of the electrode, and the like. Preferably, various resins composed of a polymer can be used. Examples of the resin include alkane-based polymers such as polyethylene, polypropylene, and poly-1,1-dimethylethylene; unsaturated polymers such as polybutadiene and polyisoprene; polystyrene, polymethylstyrene, polyvinylpyridine, and poly-N-vinylpyrrolidone. Polymers having a ring; Acrylic derivative polymers such as polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyacrylic acid, polymethacrylic acid, and polyacrylamide; polyvinyl fluoride , Fluorine-based resins such as polyvinylidene fluoride and polytetrafluoroethylene; C such as polyacrylonitrile and polyvinylidene cyanide
N-group-containing polymers; polyvinyl alcohol-based polymers such as polyvinyl acetate and polyvinyl alcohol; halogen-containing polymers such as polyvinyl chloride and polyvinylidene chloride; conductive polymers such as polyaniline; and polymers such as cellulose-based and alkoxy ether-based Can also be used. Further, a mixture of the above-mentioned polymers and the like, a modified substance, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer and the like can also be used. The weight average molecular weight of these resins is preferably 10,000
-300000, more preferably 100000-1
000000. If it is too low, the strength of the electrode decreases, which is not preferable. If it is too high, the viscosity of the coating material will increase, making it difficult to form electrodes.

The blending amount of the binder with respect to 100 parts of the active material in the electrode is preferably 0.1-30.
Parts, more preferably 1-20 parts. If the amount of the binder is too small, the strength of the electrode decreases. If the amount of the binder is too large, the battery capacity may decrease, or the ionic conductivity may decrease.

The electrode may contain additives, such as conductive materials and reinforcing materials, exhibiting various functions such as reinforcing materials, powders, fillers, and the like, if necessary. The conductive material is not particularly limited as long as it can impart conductivity by mixing an appropriate amount with the active material, but usually, acetylene black, carbon black, carbon powder such as graphite, and various metal fibers,
Foil and the like. The DBP oil absorption of the carbon powder conductive material is preferably 120 cc / 100 g or more, and especially 150 cc / 100 g.
cc / 100 g or more is preferable because it holds the electrolytic solution.

In the present invention, the electrodes are preferably provided on a conductive electrode substrate (current collector). As a current collector used in this case, for example, a foil of a metal (including an alloy) such as aluminum, iron, or copper can be preferably used. Further, a material in which a metal thin film is formed on a base material such as a polymer film can also be used. However, the material is not particularly limited as long as no problem such as elution occurs electrochemically. Further, a perforated substrate such as expanded metal or punched metal may be used. This is effective in reducing the weight of the battery itself, that is, in improving the weight energy density, and the weight can be freely changed by changing the aperture ratio. The thickness of the current collector is not particularly limited, but is preferably 1 to 50 μm, and particularly preferably 3 to 20 μm. If it is too thick, the capacity of the battery is disadvantageous. If it is too thin, the strength of the current collector will decrease.

By pre-roughening the surface of these substrates, the effect of binding to the positive and negative electrode layers can be improved. Examples of the surface roughening method include a method such as blasting and rolling with a rough roll, a polishing cloth paper to which abrasive particles are fixed, a grindstone, an emery buff, a wire brush provided with a steel wire, or the like. A mechanical polishing method for polishing the surface, an electrolytic polishing method, a chemical polishing method, and the like can be given. Further, an undercoat primer layer can be formed on the current collector. The function of the primer layer is to improve the adhesiveness of the active material coating layer of the positive electrode or the negative electrode to the current collector base material. The purpose of the present invention is to prevent a rapid decrease in capacity due to detachment of a coating film from a substrate in a charge / discharge cycle test process.

When the undercoat primer layer is used, its composition is a layer made of a resin to which conductive particles such as carbon black, graphite, and metal powder are added, or a conductive organic conjugated resin. There is no particular limitation as long as it has sufficient conductivity and electrochemical stability for the development of battery performance. Preferably to the conductive particles,
It is preferable to use carbon black or graphite which can also function as an active material. As the resin, it is preferable to use polyaniline, polypyrrole, polyacene, a disulfide-based compound, a polysulfide-based compound, or the like, which can function as an active material, because the capacity is not reduced.

In the case of a composition containing a resin to which conductive particles are added as a main component, the ratio of the resin to the conductive particles is 1-3.
It is preferably set to 00% by weight. If it is too low, the strength of the coating film is reduced, and peeling off during the process during use of the battery is not preferred. If it is too high, the conductivity will decrease and the battery characteristics will decrease. Particularly preferably, the content is in the range of 5 to 100% by weight.

The film thickness is not particularly limited as long as adhesiveness and conductivity are ensured, but is usually 0.05 to 10 μm, preferably
0.1-1 μm is good. If it is too thin, application becomes difficult and uniformity cannot be ensured. If the thickness is too large, the volume capacity of the battery is impaired.

Next, a method for forming an electrode will be described.

In the present invention, the electrode preferably contains an active material and a binder. As a preferable method for forming this electrode, the active material and the binder are dispersed and formed into a coating using a solvent capable of dissolving the binder, and the coating is applied to a current collector and dried to collect the active material with the binder. There is a method of binding on an electric body.

As the solvent which can be used when the method of forming a dispersion coating is used, any of inorganic and organic solvents which are generally used can be used as long as they can dissolve the binder used. A commonly used dispersing machine can be used for dispersion coating, and a ball mill, a sand mill, a twin-screw kneader or the like can be used.

In the case of using the method of forming a dispersed paint, there is no particular limitation on a coating apparatus for applying the paint, and slide coating or extrusion type die coating, reverse roll, gravure, knife coater, kiss coater, microgravure, knife Examples include a coater, a rod coater, and a blade coater, and the extrusion method is most preferable in consideration of the viscosity of the paint and the thickness of the applied film.

The dried coating film can be subjected to a consolidation step using a calender or the like, which is particularly preferred from the viewpoint of improving the coating film strength and the adhesiveness. As the pressure of the calender, a pressure necessary for obtaining the required coating film density and coating film strength can be applied. In the calendering step, the temperature may be applied at the same time.

The electrode thus obtained usually has voids. In the present invention, it is preferable that a non-fluid electrolyte is present in the gap of such an electrode. In order for the non-fluid electrolyte to be present in the gap, it is preferable that the electrolyte paint is supplied and then non-fluidized to form a non-fluid electrolyte. The electrolyte paint and the non-flowable electrolyte that can be used will be described later.

The method of manufacturing the electrode is not limited to the above. For example, an active material and an electrolyte paint are mixed and dispersed to form a paste, which is coated on a current collector and then subjected to a non-fluidizing treatment. By doing so, an electrode having a non-fluid electrolyte can also be obtained.

The non-fluid electrolyte will be described below.

Examples of the non-fluid electrolyte include a gel electrolyte obtained by forming an electrolyte solution into a matrix with a polymer, a completely solid electrolyte consisting of only a solid, and the like.

In the case of a gel electrolyte, an electrolyte obtained by dissolving a supporting electrolyte in a solvent is used. As the solvent, water is usually used, and in the case of a lithium battery, a non-aqueous organic solvent is used. The effect of the present invention is particularly effective when a non-aqueous organic solvent is used. In the case of a lithium battery, a lithium battery as a supporting electrolyte dissolved in a nonaqueous solvent is generally used.

The supporting electrolyte contained in the electrolyte for the lithium battery is stable as an electrolyte with respect to the positive electrode active material and the negative electrode active material, and lithium ions undergo an electrochemical reaction with the positive electrode active material or the negative electrode active material. Any non-aqueous substance capable of performing the transfer can be used. Specifically, LiPF ₆ , LiAsF ₆ ,
LiSbF ₆ , LiBF ₄ , LiClO ₄ , LiI, Li
Br, LiCl, LiAlCl, LiHF ₂ , LiSC
N, LiSO ₃ CF _{2 and the} like. Among them, LiPF ₆ and LiClO ₄ are particularly preferable. The content of these supporting electrolytes in the electrolyte is generally from 0.5 to
2.5 mol / L.

The type of the non-aqueous solvent used for the electrolyte for the lithium battery is not particularly limited, but a solvent having a relatively high dielectric constant is preferably used. Specifically, cyclic carbonates such as ethylene carbonate and propylene carbonate, and acyclic carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate. −
Tetrahydrofuran, 2-methyltetrahydrofuran,
One or a mixture of two or more of glymes such as dimethoxyethane, lactones such as γ-butyl lactone, sulfur compounds such as sulfolane, and nitriles such as acetonitrile can be exemplified. Of these, cyclic carbohydrates such as ethylene carbonate and propylene carbonate are particularly preferred.
One or more mixed solutions selected from acyclic carbonates such as carbonates, dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate are preferred.

As a method for defluidizing the electrolytic solution, a polymerizable monomer having a portion having a high affinity for the electrolytic solution is dissolved in the electrolytic solution, and the solution is polymerized to be polymerized. The method (1) of gelling the liquid is preferably used. In addition, the electrolyte solution where the polymer is dissolved at high temperature,
The technique (2) of gelling by cooling can also be used.

In the above method (1), a monomer-containing electrolyte paint is prepared and then subjected to a cross-linking reaction to give a non-fluidized electrolyte. Is added to the electrolyte.

Examples of the polymerizable monomer include those having an unsaturated double bond such as an acryloyl group, a methacryloyl group, a vinyl group and an allyl group. For example, acrylic acid, methyl acrylate, ethyl acrylate, ethoxyethyl acrylate, methoxyethyl acrylate, ethoxyethoxyethyl acrylate, polyethylene glycol monoacrylate, ethoxyethyl methacrylate, methoxyethyl methacrylate, ethoxyethoxyethyl methacrylate, polyethylene glycol monomethacrylate, N, N diethylaminoethyl acrylate, N, N dimethylaminoethyl acrylate, glycidyl acrylate, allyl acrylate, acrylonitrile, N-vinylpyrrolidone, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, diethylene glycol dime Acrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polyalkylene glycol diacrylate, polyalkylene glycol dimethacrylate, etc. can be used, and further trimethylolpropane alkoxylate triacrylate, pentaerythritol alkoxylate triacrylate Trifunctional monomers such as pentaerythritol alkoxylate tetraacrylate, and ditrimethylolpropane alkoxylate tetraacrylate.
Monofunctional or higher functional monomers can also be used. Among these, those which are preferable in terms of reactivity, polarity, safety and the like may be used alone or in combination.

These monomers can be polymerized by heat, ultraviolet rays, electron beams or the like to make the electrolyte non-fluid. In this case, a polymerization initiator may be added to the electrolytic solution in order to make the reaction proceed effectively. As the polymerization initiator, benzoin, benzyl, acetophenone, benzophenone, Michler's ketone, biacetyl, benzoyl peroxide and the like can be used, and further, t-butyl peroxy neodecanoate, α-cumyl peroxy neodecanoate, t -Peroxy neodecanoates such as hexyl peroxy neodecanoate, 1-cyclohexyl 1-methylethyl peroxy neodecanoate, t-amyl peroxy neodecanoate, t-butyl peroxy neohepta Peroxy such as noate, α-cumylperoxyneoheptanoate, t-hexylperoxyneoheptanoate, 1-cyclohexyl-1-methylethylperoxyneoheptanoate, t-amylperoxyheptanoate, etc. Also use neoheptanoate, etc. Can be used.

Further, a polymer which is produced by polycondensation of polyester, polyamide, polycarbonate, polyimide or the like, or a polymer which produces a polymer produced by polyaddition of polyurethane or polyurea may be used as the polymerizable monomer. it can.

In the method (2) using an electrolyte paint containing a polymer from the beginning, a polymer that dissolves in an electrolytic solution at a high temperature and forms a gel electrolyte at a normal temperature can be preferably used. Any polymer can be used as long as it is a polymer having such properties and is stable as a battery material. Examples thereof include polymers having a ring such as polyvinylpyridine and poly-N-vinylpyrrolidone; polymethacrylic acid Acrylic derivative polymers such as methyl, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyacrylic acid, polymethacrylic acid polyacrylamide; fluororesins such as polyvinyl fluoride and polyvinylidene fluoride A CN-containing polymer such as polyacrylonitrile and polyvinylidene cyanide; a polyvinyl alcohol-based polymer such as polyvinyl acetate and polyvinyl alcohol; and a halogen-containing polymer such as polyvinyl chloride and polyvinylidene chloride. Further, a mixture of the above-mentioned polymers, a modified product, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer, or the like can also be used. As described later, since the electrolyte and the electrolyte used in the lithium battery have polarity, it is preferable that the polymer also has a certain degree of polarity. The weight average molecular weight of these polymers is preferably 10,000 to 500,000.
It is in the range of 0. If the molecular weight is low, it is difficult to form a gel. If the molecular weight is high, the viscosity becomes too high and handling becomes difficult. The concentration of the polymer in the electrolytic solution is preferably changed according to the molecular weight, preferably from 0.1% to 3%.
0%. If the concentration is 0.1% or less, it is difficult to form a gel, the retention of the electrolyte is reduced, and problems of flow and liquid leakage occur. If the concentration is 30% or more, the viscosity becomes too high, causing difficulty in the process, and the proportion of the electrolytic solution is reduced, the ionic conductivity is reduced, and the battery characteristics such as rate characteristics are deteriorated.

A completely solid electrolyte may be used as the non-fluid electrolyte. In this case, a polymer containing a supporting electrolyte in a polymer such as a polyethylene oxide polymer can be used. If a paint having the above-mentioned composition except for the solvent is used as the electrolyte electrolyte paint in this case, the electrolyte can be completely solidified. In this case, as a non-fluidizing method, the above (1) using a monomer is preferable because of its low viscosity.

The porous membrane used in the present invention is not particularly limited. For example, a woven fabric, a nonwoven fabric made of various natural fibers and synthetic fibers, a porous film made of a polymer such as polyolefin, and a powder made of a polymer and a polymer. A porous membrane or the like can be preferably used.

The method of manufacturing the unit battery element according to the present invention is as follows. The porous film is filled with an electrolyte paint, and the positive electrode and the negative electrode are separated from each other while the electrolyte paint is present in the electrode. It is preferable to perform a method of performing non-fluidizing treatment of the electrolyte paint by laminating through the layers. As a result, the non-fluid electrolyte in the electrode and the non-fluid electrolyte in the porous membrane are integrated, and a battery having excellent battery characteristics such as rate characteristics and cycle characteristics can be obtained. Of course, it is also possible to delaminate the electrolyte paint for the electrodes and the porous membrane before laminating them.

In the present invention, the obtained unit battery element is a flat plate. However, the unit battery element may be a monocell composed of a positive electrode and a negative electrode in which an active material is bonded to one surface of a current collector, It may be a bicell in which an electrode having an active material bonded thereto is sandwiched between two counter electrodes having an active material bonded on one surface, or a structure in which a larger number are stacked. Preferably, a monocell or a bicell is preferable from the viewpoint of easy formation of the unit cell element.

A plurality of unit battery elements are stacked using a guide frame or a box-shaped storage container.

A thin battery can be realized by tightly storing a plurality of unit battery elements in a case made of, for example, a film having a variable shape. Examples of the case made of a film having shape changeability include a lightweight and thin laminated film made of a polymer film. As the laminate film, a film made of a laminate material of a metal foil and a polymer film can be suitably used. When storing, it is preferable to perform vacuum sealing. Also, the unit battery elements can be put into a case having a box-shaped structure and stacked.

[0076]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and may be appropriately modified and practiced without departing from the gist thereof. it can. Parts in the composition indicate parts by weight.

First, the following paints were prepared.

[Positive electrode coating] Composition Lithium cobaltate 90 parts Acetylene black 5 parts Polyvinylidene fluoride 5 parts N-methyl-2-hydroxylithone 80 parts All of the above raw materials were kneaded for 2 hours by a kneader to form a paste for a positive electrode. . Polyvinylidene fluoride has a glass transition temperature of -40C, a melting point of 160-170C, and a decomposition temperature of 350C.

[Negative electrode paint] Composition Graphite (particle size: 15 μm) 90 parts Polyvinylidene fluoride 10 parts N-methyl-2-hydroxylithone 100 parts All of the above-mentioned raw materials were kneaded for 2 hours by a kneader to obtain a paste for a negative electrode.

[Electrolyte paint] Composition Tetraethylene glycol diacrylate 14 parts Polyethylene oxide triacrylate 7 parts Lithium perchlorate 21 parts Polymerization initiator 1 part Additive (spirodilactone) 14 parts Electrolyte solution (propylene carbonate) 120 parts Electrolyte (ethylene carbonate) 120 parts All of the above compositions were mixed, stirred and dissolved to obtain an electrolyte paint.

Next, the positive electrode paint was applied on a 20 μm-thick aluminum current collector base material, and the negative electrode paint was applied on a 20 μm-thick copper current collector base material by extrusion die coating, followed by drying. A porous electrode member bound on the current collector with a binder was prepared. Next, the size of the part excluding the tab is 30 mm x 40 mm for the positive electrode,
The negative electrode was cut out to have a size of 32 mm × 42 mm.

Example 1 An electrolyte paint was applied to the positive electrode and the negative electrode, and a polymer porous film of 35 mm × 50 mm in which the electrolyte paint was soaked was sandwiched and laminated. The resultant was heated at 90 ° C. for 30 minutes to form an electrolyte. It was made non-fluidized to form a flat unit battery element. Next, the porous film protruding from one of the 42 mm side and the 32 mm side of the negative electrode was cut so as to have the same size as the negative electrode. Ten unit battery elements were stacked using a jig having a guide frame and fixed with tape to form a stacked battery. Next, a tab for taking out a current was connected, and a laminated battery comprising an aluminum film and a polymer film was vacuum-sealed and housed in a bag-shaped case formed oppositely to obtain a flat battery.

Comparative Example 1 In Example 1, the cut side of the protruding porous film was cut so that the protruding porous film was 0.5 mm larger than the negative electrode.

Comparative Example 2 In Example 1, cutting of the protruding porous membrane was omitted.

[Evaluation of Characteristics] The ease of the lamination process was evaluated based on the degree of hooking during lamination of the unit cell elements and the degree of adhesion of the non-fluidized electrolyte to the jig.

In Example 1, the unit battery elements were hardly hooked, and were smoothly stacked in the jig. The adhesion of the non-fluidized electrolyte was extremely small. Comparative Example 1
In, a phenomenon was observed in which the unit battery element was hooked on the jig and became oblique. In addition, the adhesion of the non-fluidizing electrolyte progressed and the phenomenon of catching increased with time. In Comparative Example 2, in most cases, the unit battery elements were hooked on the jig, and the stacking could not be performed unless a pressing step was performed each time. Further, in some batteries, when the battery was pressed, the porous membrane was broken and the electrodes were peeled off, resulting in a defective battery and requiring a cleaning step.

[0087]

As described above, according to the present invention, a flat laminated battery using a non-fluidized electrolyte can be obtained with high productivity. The stacked battery of the present invention has a high capacity, is excellent in battery performance such as rate characteristics and cycle characteristics, and is excellent in safety and productivity.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a unit battery element according to the present invention.

FIG. 2 is a front view of the unit battery element of FIG.

FIG. 3 is a top view of the unit battery element of FIG. 1;

FIG. 4 is a perspective view of a conventional unit battery element.

FIG. 5 is a front view of the unit battery element of FIG.

FIG. 6 is a top view of the unit battery element of FIG. 4;

FIG. 7 is a perspective view showing another example of the unit battery element according to the present invention.

FIG. 8 is a front view of the unit battery element of FIG. 7;

FIG. 9 is a right side view of the unit battery element of FIG. 7;

FIG. 10 is a left side view of the unit battery element of FIG. 7;

FIG. 11 is a top view of the unit battery element of FIG. 7;

[Explanation of symbols]

 11, 21, 71 Unit battery element 12, 22, 72 Conductive positive electrode substrate 13, 23, 73 Positive electrode (first electrode) 14, 24, 74 Porous film 15, 25, 75 Negative electrode (second electrode) 16,26,76 Conductive negative electrode substrate

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 5H029 AJ03 AJ05 AJ12 AJ14 AJ15 AK01 AK03 AK05 AK16 AK18 AL06 AL07 AL12 AM00 AM01 AM02 AM03 AM04 AM05 AM07 AM16 BJ04 BJ12 DJ02 DJ04 DJ05 DJ07 DJ13 DJ16 HJ04 HJ12

Claims (9)

[Claims] 1. A flat unit battery comprising a first electrode, a second electrode, a porous membrane and a non-fluid electrolyte disposed between the first electrode and the second electrode. In the device, at least a part of an outer edge of the unit battery element is the first battery.
A unit cell element formed at the outer edge of the first electrode and / or the second electrode. 2. The unit battery element has a substantially rectangular shape, and at least a part of an outer edge of the unit battery element is formed by the first electrode and / or the second electrode on at least two opposing sides thereof. The unit battery element according to claim 1, wherein: 3. A flat unit battery comprising a first electrode, a second electrode, a porous membrane and a non-fluid electrolyte disposed between the first electrode and the second electrode. In the device, at least a part of the outer edge of the porous membrane overlaps or is located inside the outer edge of the second electrode, and is located outside the outer edge of the first electrode. A unit battery element which is extended. 4. The unit battery element according to claim 3, wherein the second electrode is a negative electrode. 5. The first electrode, the second electrode, and the porous film are each substantially rectangular, and at least a part of an outer edge of the porous film on at least two opposite sides of the porous film. 5. The unit battery element according to claim 3, wherein the unit cell overlaps or is located inside the outer edge of the second electrode and extends outside the outer edge of the first electrode. 6. . 6. The unit battery element according to claim 1, wherein a conductive electrode base material is provided on a back surface of at least one of the first and second electrodes. 7. The unit battery element according to claim 6, wherein an outer peripheral edge of the electrode and a conductive electrode substrate on a back surface thereof coincide with each other. 8. The unit battery element according to claim 1, wherein the thickness of the porous film is 20 μm or less. 9. A stacked battery comprising a plurality of the unit battery elements according to claim 1 stacked in a thickness direction and housed in a case.