JP2000294290A - Manufacturing method of secondary battery - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a method of manufacturing a secondary battery improved particularly so that the concentration of an active material in an electrode can be increased. A step (A) of compression-molding an electrode preparation mixture containing at least an active material, an electrolytic solution and a gel-forming monomer on a current collector on a positive electrode and / or a negative electrode side; And a polymerization step (B). In the above step (A), a current collector is placed on the lower mold surface using a compression molding mold including a lower mold and an upper mold, and the shape is adjusted. The current collector is similar to the current collector and the size is 30 to
The above-mentioned electrode preparation mixture processed into a sheet shape of 90% is supplied to substantially the center of the current collector, and then subjected to compression molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a secondary battery, and more particularly to an industrially advantageous method for manufacturing a secondary battery having excellent characteristics.

[0002]

2. Description of the Related Art Conventionally, a positive electrode and / or a negative electrode has at least a current collector and an active material layer fixed on the current collector with a polymer and holding an electrolytic solution.
A secondary battery in which the above-described polymer is derived from a gel-forming monomer, and the above-described positive electrode and negative electrode are laminated in a flat plate via an electrolyte layer in which an electrolyte is held by a polymer derived from the gel-forming monomer is For example, it is known as a lithium secondary battery.

[0003] As a method for manufacturing the above-mentioned lithium secondary battery, for example, a method for preparing an electrode containing an active material, an electrolytic solution and a gel-forming monomer is applied on a current collector, and then the gel-forming monomer is coated. To form a positive electrode and a negative electrode, and then applying a gel electrolyte layer paint containing an electrolyte solution and a gel-forming monomer on the positive electrode or the negative electrode, and then polymerizing the gel-forming monomer. Is known (JP-A-5-41247).

However, in the case of the above-mentioned method, the viscosity of the electrode preparation paint is limited due to the necessity of smooth application, and the capacity of the battery is sufficiently increased by increasing the amount of the active material in the electrode. There is a problem that you can not do. In particular, the above problem is remarkable in the case of an industrial process that requires continuous coating.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has as its object to manufacture a secondary battery improved so that the concentration of an active material in an electrode can be increased. It is to provide a method.

[0006]

As a result of various studies, the present inventors have found that the above object can be easily achieved by using compression molding means, and have completed the present invention. Was.

[0007]

That is, the gist of the present invention is that a positive electrode and / or a negative electrode comprises at least a current collector and an active material layer fixed on the current collector with a polymer and holding an electrolyte. In addition, the above-mentioned polymer is derived from the gel-forming monomer, and the above-described positive electrode and negative electrode are laminated in a plate shape via an electrolyte layer in which an electrolyte is held by the polymer derived from the gel-forming monomer. A method for producing a secondary battery, comprising a step (A) of compression-molding an electrode preparation mixture containing at least an active material, an electrolytic solution and a gel-forming monomer on a current collector on a positive electrode and / or a negative electrode side; And a polymerization step (B) of the gel-forming monomer, and in the step (A),
A current collector is mounted on the lower mold surface using a compression mold composed of a lower mold and an upper mold, and the shape is substantially similar to the current collector and the size is 30 to 90 of the current collector. The above-mentioned electrode preparation mixture processed into a sheet shape, which is a%, is supplied to substantially the center of the current collector,
Then, compression molding is carried out.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The production method of the present invention comprises a positive electrode and / or a negative electrode comprising at least a current collector and an active material layer fixed on the current collector with a polymer and holding an electrolytic solution. Derived from monomers, and
As long as it is a secondary battery in which the above-described positive electrode and negative electrode are laminated in a plate shape via an electrolyte layer in which an electrolyte is held by a polymer derived from a gel-forming monomer, the present invention can be applied to various batteries. In the description, a lithium secondary battery, which is a typical secondary battery, will be taken as an example. In addition, any one of the above-described electrodes (usually, a negative electrode) can be formed of a metal itself such as a lithium foil.

As the current collector, usually, a metal foil such as aluminum or copper or a metal net is used, and its thickness is appropriately selected, but it is usually 1 to 50 μm, preferably 5 to 30 μm. The current collector is preferably used after being subjected to a roughening treatment in advance in order to increase the adhesive strength with the active material layer fixed thereon. Examples of the surface roughening method include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method. In the mechanical polishing method, a polishing cloth paper having abrasive particles fixed thereon, a grindstone, an emery buff, a wire brush provided with a steel wire, or the like is used.

Further, the current collector may be provided with an adhesive layer in order to increase the adhesive strength with the active material layer. The adhesive layer is usually composed of a mixture containing an adhesive compound and a binder resin, and as such a mixture, for example,
A mixture described in JP-B-7-70328 can be used. The thickness of the adhesive layer is usually 0.05 to 1
0 μm, preferably 0.1 to 1 μm.

As the positive electrode active material composed of an inorganic compound,
Transition metal oxides, composite oxides of lithium and transition metals,
Transition metal sulfide and the like. As the above transition metal, Fe, Co, Ni, Mn and the like are used. Specific examples of the inorganic compound used for the positive electrode active material include Mn
Transition metal oxides such as O, V ₂ O ₅ , V ₆ O ₁₃ and TiO ₂ ; composite oxides of lithium and transition metals such as lithium nickelate, lithium cobaltate and lithium manganate; TiS
2, transition metal sulfides such as FeS and MoS ₂ . As a positive electrode active material composed of an organic compound, for example,
Examples thereof include polyaniline, polypyrrole, polyacene, disulfide-based compounds, polysulfide-based compounds, and N-fluoropyridinium salts. The particle size of the positive electrode active material is
Usually, it is 1 to 30 μm, preferably 1 to 10 μm.

Examples of the negative electrode active material include carbon-based active materials such as graphite and coke. Examples of the negative electrode active material include oxides and sulfates of silicon, tin, zinc, manganese, iron, nickel and the like, metallic lithium, Li-Al, Li
Lithium alloys such as -Bi-Cd and Li-Sn-Cd, lithium transition metal nitrides, silicon and the like can also be used. The particle size of the negative electrode active material is usually 1 to 50 μm, preferably 5 to 2 μm.
0 μm.

As the lithium salt (supporting electrolyte) which is a component of the electrolytic solution, LiPF ₆ or LiClO ₄ is preferable. On the other hand, as a solvent that is another component of the electrolytic solution, one or more selected from cyclic carbonates such as ethylene carbonate and propylene carbonate, and non-cyclic carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate are used. Are preferred. In order to enhance the stability, performance and life of the battery, for example, trifluoropropylene carbonate, vinylene carbonate, catechol carbonate,
1,6-Dioxaspiro [4,4] nonane
Additives such as -2,7-done and 12-crown-4-ether may be added.

As the gel-forming monomer (precursor monomer of the polymer), acrylic acid, methyl acrylate, ethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, 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, Reactive unsaturated group-containing monomers such as triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate. The “gel-forming monomer” in the present invention is not limited to only the compound corresponding to the minimum repeating unit constituting the polymer, but also includes other compounds that form the polymer by polymerization (for example, dimer).

As a method for polymerizing the above-mentioned gel-forming monomer, there are heating polymerization and ultraviolet irradiation polymerization as described later. Therefore, the above-mentioned gel-forming monomer is usually used together with various polymerization initiators according to the above-mentioned polymerization method.

Examples of the thermal polymerization initiator include 1,1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane and 2,2-bis- [4,4-di (tert-butylperoxy). Cyclohexyl) propane], 1,
1-di (tert-butylperoxy) -cyclohexane, tert-butylperoxy-3,5,5-trimethylhexanate, tert-butylperoxy-2
-Ethyl hexanonate, dibenzoyl peroxide and the like. Examples of the ultraviolet polymerization initiator include benzoin, benzyl, acetophenone, benzophenone, Michler's ketone, biacetyl, benzoyl peroxide and the like.

If necessary, the electrode may contain additives exhibiting various functions such as a conductive material and a reinforcing material. The conductive material is not particularly limited as long as it is capable of imparting conductivity by being mixed in an appropriate amount with the active material, and usually includes acetylene black, carbon black, carbon powder such as graphite, and various metal fibers and foils. . In addition, to increase the stability and life of the battery, trifluoropropylene carbonate, vinylene carbonate,
Catechol carbonate, 1,6-Dioxaspir
o [4,4] nonane-2,7-dione, 12
-Crown-4-ether and the like can be used. Further, as a reinforcing material, various inorganic and organic spherical, plate-like, rod-like,
Fillers such as fibrous can be used.

Further, the electrode may contain a binder for improving the mechanical strength. Examples of such a binder include various resins in addition to inorganic compounds such as silicate and glass. As the binder resin, for example, polyethylene, polypropylene, alkane-based polymers such as poly-1,1-dimethylethylene, polybutadiene, unsaturated polymers such as polyisoprene,
Polymers having a ring such as polystyrene, polymethylstyrene, polyvinylpyridine, poly-N-vinylpyrrolidone, polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate,
Acrylic polymers such as polyethyl acrylate, polyacrylic acid, polymethacrylic acid, and polyacrylamide; fluorine resins such as polyvinyl fluoride, polyvinylidene fluoride, and polytetrafluoroethylene; and CN groups such as polyacrylonitrile and polyvinylidene cyanide Containing polymer,
Examples thereof include polyvinyl alcohol-based polymers such as polyvinyl acetate and polyvinyl alcohol, halogen-containing polymers such as polyvinyl chloride and polyvinylidene chloride, and conductive polymers such as polyaniline. The weight average molecular weight of these resins is usually from 1,000 to 3,000,000, preferably from 10,000 to 500,000.

The positive electrode and / or the negative electrode in the present invention is basically the same as a conventional lithium secondary battery, and is formed by fixing at least a current collector and a polymer on the current collector and holding an electrolyte. And an active material layer, wherein the polymer is derived from a gel-forming monomer.

The feature of the manufacturing method of the present invention lies in the manufacturing process of the electrode. One feature of the production method of the present invention is a step of compression-molding an electrode preparation mixture containing at least an active material, an electrolytic solution, and a gel-forming monomer on a current collector on the positive electrode and / or negative electrode side ( A) and the step of polymerizing the gel-forming monomer (B).

In the above-mentioned compression molding step, specifically, a current collector having a predetermined shape (substantially the same size as the cavity) is placed on the lower die (cavity) surface of the compression molding die, The mixture for electrode preparation as a molding material is poured thereon, the upper mold (core) is closed, and then compression molding is performed by a compression molding machine (press).

In the present invention, since a current collector having a desired shape is used as a current collector corresponding to a starting material in the manufacture of a secondary battery, a punching process that wastes material is not required. In this case, for example, only the positive electrode can be formed by the above-described method, and the negative electrode can be formed of a metal having a predetermined shape. Alternatively, both electrodes can be formed by the above-described method.

The mixture for preparing an electrode to be subjected to the above-mentioned compression molding is prepared from the above-mentioned material for forming an electrode, and may contain a viscosity modifier if necessary.

The ratio of the active material in the electrode preparation mixture is determined from the following viewpoint. That is, when the ratio of the active material is too large, the characteristics at a high rate tend to deteriorate, and compression molding tends to be difficult. On the other hand, if the proportion of the active material is too small, a secondary battery with a sufficiently increased capacity cannot be obtained. By the way, in the present invention, a coating step is not necessary for manufacturing an electrode, and therefore, the degree of freedom of the viscosity of the electrode preparation mixture is high. Therefore,
By increasing the active material content in the electrode preparation mixture, in other words, by increasing the ratio of the active material in the active material layer that is a component of the electrode, it is possible to easily improve the capacity of the secondary battery. I can do it. In the present invention, the lower limit of the proportion of the active material in the electrode preparation mixture is usually 20% by weight, preferably 40% by weight, more preferably 60% by weight, and particularly preferably 70% by weight. It is usually 90% by weight, preferably 80% by weight.

The proportion of the electrolytic solution in the electrode preparation mixture is determined from the following viewpoints. That is, when the proportion of the electrolytic solution is too large, the characteristics at a high rate tend to be deteriorated, and compression molding tends to be difficult. On the other hand, if the proportion of the electrolyte is too small, a secondary battery with a sufficiently increased capacity cannot be obtained. In the present invention,
The lower limit of the proportion of the electrolytic solution in the electrode preparation mixture is usually 1
It is 0% by weight, preferably 20% by weight, and the upper limit is usually 60% by weight, preferably 40% by weight. The proportion of the gel-forming monomer in the electrode preparation mixture is determined in the same manner as in the case of the above-mentioned electrolyte.

The ratio of the gel-forming monomer to the total amount of the electrolyte and the gel-forming monomer is determined from the following viewpoints. That is, if the proportion of the gel-forming monomer is too large, the properties at high rates tend to deteriorate,
If the amount is too small, the mechanical strength of the electrode tends to be insufficient. In the present invention, the lower limit of the proportion of the gel-forming monomer is usually 1% by weight, preferably 5% by weight, and the upper limit is usually 70% by weight, preferably 40% by weight, more preferably 20% by weight. It is said.

The proportion of other additives, a polymerization initiator, additives such as a conductive material and a reinforcing material, a binder and a viscosity modifier is usually 20% by weight or less based on the total amount of the active material, the electrolytic solution and the gel-forming monomer. , Preferably 10% by weight or less,
More preferably, the content is 5% by weight or less. When the proportion of each of the above components exceeds 20% by weight, the proportions of the active material, the electrolytic solution, and the gel-forming monomer tend to be relatively low, which is not preferable. When each of the above components is used, the lower limit is usually 0.1% by weight based on the total amount of the active material, the electrolytic solution and the gel-forming monomer.

The mixture for preparing an electrode to be subjected to compression molding is as follows:
It must be adjusted to have flow properties that allow compression molding. Such viscosity adjustment is performed by selecting the particle size of the active material, the type of the electrolytic solution, and the amount used.
In addition, a solvent is used if necessary.

Another feature of the manufacturing method of the present invention is that, in the above step (A), in the above step (A), a compression mold comprising a lower mold and an upper mold is used, A current collector is placed on the current collector, and the above-described electrode preparation mixture processed into a sheet having a shape substantially similar to the current collector and having a size of 30 to 90% of the current collector is used as the current collector. The point is that it is supplied to approximately the center, and then compression molded.

The reason for using the electrode preparation mixture processed as described above as a molding material is as follows. That is, in the compression molding of the above-mentioned mixture containing a solid active material that does not undergo plastic deformation (flow) and a binder that undergoes plastic deformation (flow), sometimes the two materials having different properties cause phase separation. May not be deformed with a uniform composition. In short, phase separation occurs or a so-called weld line occurs depending on how much the molding material charged into the mold is deformed. Therefore, in the present invention, the electrode preparation mixture processed as described above is used as a molding material in order to prevent the occurrence of phase separation and weld lines in the compression molding process and to obtain an active material layer having a uniform composition.

When the mixture for electrode preparation is put on the current collector in the form of, for example, a ball or a rod, or when it is put over many points on the current collector, deformation with a uniform composition is achieved. I can't do it. Even when the mixture for preparing an electrode is in the form of a sheet, the same result as described above can be obtained when the mixture is put into the end of the current collector. Furthermore, even when the electrode preparation mixture is processed into a sheet shape substantially similar to the current collector, if the size is too small, the deformation ratio is too large, and the same result as above is obtained. . On the other hand, if the size is too large, there is no problem as described above, but it is not easy to put in, and has a drawback that the deformation rate is too small and the adhesion to the current collector is low. In the present invention, the lower limit of the ratio of the size of the sheet-shaped mixture to the current collector is set to 30%, but is preferably set to 50%. On the other hand, the upper limit value of the size ratio is set to 90%, and is preferably set to 80%.

The thickness of the electrode-preparing mixture (in other words, the active material layer after the polymerization step described later) which is compression-molded on the current collector is determined from the following viewpoints. That is, when the active material layer is too thick, the rate characteristics tend to deteriorate, and when the active material layer is too thin, the capacity of the secondary battery as a whole becomes too low. In the present invention, the lower limit of the thickness of the active material layer is usually 1 μm, preferably 30 μm, and the upper limit is usually 1000 μm, preferably 200 μm.

The polymerization step itself of the gel-forming monomer can be carried out according to known heat polymerization or ultraviolet irradiation polymerization. Then, for example, a heat polymerization step can be performed simultaneously with the compression molding step, and after the compression molding step, a polymerization step can be performed on each of the positive electrode side and the negative electrode side. Further, a positive electrode and a negative electrode are formed by polymerization, and then a coating solution for a gel electrolyte layer containing an electrolytic solution and a gel-forming monomer is applied on the positive electrode or the negative electrode, and then the gel-forming monomer is polymerized. Methods can also be employed.

In the present invention, in the polymerization step of the gel-forming monomer, after the above-mentioned compression-molding step, a sheet carrying the electrolyte and the gel-forming monomer is interposed between the compression-molded electrode preparation mixtures. And heat treatment (thermal polymerization). According to such a method, each electrode electrode and the gel electrolyte layer are better integrated based on the wet state by the gel-forming monomer on the bonding surface, compared to the case where the positive electrode side and the negative electrode side are separately polymerized. As a result, a battery with low resistance is obtained.

As the sheet for supporting the electrolytic solution and the gel-forming monomer, various porous membranes and nonwoven fabrics used as battery separators can be used, and specifically, paper such as paper, Japanese paper, etc. And various types of natural and synthetic fibers, and commercially available filters used for separation and purification. The thickness of the sheet is usually 5
It is 200 μm, preferably 10 to 150 μm, more preferably 10 to 80 μm. In addition, the thermal polymerization of the gel-forming monomer in the above-mentioned laminated state is usually performed at 60 to 150 ° C.
Preferably, it is performed at a temperature of 60 to 100 ° C.

The battery element obtained as described above, in which the positive electrode and the negative electrode are laminated in a flat plate via a gel electrolyte layer in which an electrolyte is held in a polymer, is required to have, for example, external terminals and the like. After attaching and processing the components, a plurality of the components are stacked as necessary, and are housed in a case to form a secondary battery. As the case, a shape-variable case having flexibility, flexibility, flexibility, or the like may be used, or a rigid case may be used. Examples of the material of the case include plastic, a polymer film, a metal film, rubber, and a thin metal plate.

[0037]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the following examples,
“Parts” means “parts by weight”. In addition, “Photomer 4050” and “Ph
Each of the “automer 4158” is a polyethylene oxide manufactured by Henkel and having an acrylic group bonded to the terminal via an ester group.

Example 1 <Preparation of mixture for electrode and mixture for formation of gel electrolyte layer> According to the composition shown in the following Tables 1 and 2, kneading and dispersion treatment was carried out in a kneader for 8 hours to prepare a coating for the positive electrode and a coating for the negative electrode. Prepared. Further, a composition for forming a gel electrolyte layer was prepared according to the composition shown in Table 3 below.

[0039]

(Table 1) (Positive electrode mixture) LiCoO ₂ (active material): 75.0 parts Acetylene black (conductive material): 6.0 parts Propylene carbonate (PC) (electrolyte): 8.0 parts Ethylene carbonate (EC) (Electrolytic solution): 8.0 parts LiClO ₄ (supporting electrolyte): 1.0 part “Photomer 4050”: 1.1 parts “Photomer 4158”: 1.1 parts Thermal crosslinking initiator (“Trignox21” manufactured by Ciba Geigy): 0 .5 copies

[0040]

(Table 2) (Mixture for negative electrode) Graphite (active material): 78.0 parts Propylene carbonate (PC) (electrolyte): 7.4 parts Ethylene carbonate (EC) (electrolyte): 7.4 parts LiClO ₄ ( Supporting electrolyte): 0.9 part "Photomer 4050": 1.8 parts "Photomer 4158": 1.8 parts Thermal crosslinking initiator ("Trignox21" manufactured by Ciba Geigy): 0.5 part

[0041]

(Table 3) (Mixture for forming gel electrolyte layer) Propylene carbonate (PC) (electrolyte): 44.0 parts Ethylene carbonate (EC) (electrolyte): 44.0 parts LiClO ₄ (supporting electrolyte): 5 parts “Photomer 4050”: 4.7 parts “Photomer 4158”: 2.3 parts Thermal crosslinking initiator (“Trignox21” manufactured by Ciba Geigy): 0.1 part

<Formation of Electrode and Formation of Electrolyte Layer> As a compression mold, the R of each corner of the lower mold and the upper mold is 1.5 mm
A rectangular compression mold (length and width: about 10 cm) having a gap of 20 μm and a draft taper of 1.0 ° was used. As the current collector, a 20-μm-thick aluminum foil (positive electrode) and a copper foil (negative electrode) punched into a shape (R: 1.5 mm, vertical and horizontal: about 10 cm) following the shape in the mold are used. did. The mixture for preparing the electrodes for the positive electrode and the negative electrode was processed in advance into a sheet having a length and width of about 8 cm and a thickness of 80 μm.

First, a current collector is placed on the lower mold surface, and a mixture (sheet) for preparing an electrode for a positive electrode and a negative electrode is poured into a substantially central portion thereof, and the upper mold (core) is closed. Press molding was performed by a compression molding machine. No weld lines were observed on the surfaces of the obtained positive and negative electrodes. Then, after impregnating a non-woven fabric having a thickness of about 60 μ with the same shape as that of the current collector into the mixture for forming a gel electrolyte layer, the mixture is interposed between the positive electrode side and the negative electrode side obtained above at 90 ° C. At 10
Heated for a minute.

<Packaging Step> Next, the three battery elements obtained above are stacked so that the same poles are overlapped, and a positive electrode terminal and a negative electrode terminal are attached to each positive electrode terminal and each negative electrode terminal. It was sealed in a vacuum pack with a lid to produce a laminated lithium secondary battery.

[0045]

According to the present invention, the capacity, cycle characteristics,
Although a secondary battery having excellent rate characteristics is provided, the secondary battery of the present invention has an excellent capacity particularly due to a high concentration of the active material in the electrode, and the current collector and the active material layer are firmly formed by compression molding. The cycle characteristics are excellent because the adhesive is fixed and the adhesion is good. Furthermore, according to the present invention, since the shape of the electrode is determined by molding, the material for forming the electrode can be used without waste, and the shape of the electrode can be arbitrarily selected. Further, according to the present invention, an active material layer having a uniform composition can be obtained by preventing phase separation and generation of weld lines of the electrode preparation mixture during compression molding.

Continued on the front page (72) Inventor Dennis G. Photo, Massachusetts, USA 01720 Acton Arlington Street 359 F-term (Reference) 5H014 AA02 BB00 BB01 BB05 CC01 EE02 HH06 5H029 AJ02 AK02 AK03 AK05 AK16 AL01 AL06 AL07 AL11 AM07 AM04 BJ12 CJ02 CJ06 CJ08 CJ11 DJ04 DJ07 DJ08 HJ07

Claims (2)

[Claims] 1. A positive electrode and / or a negative electrode comprising at least a current collector and an active material layer fixed on the current collector with a polymer and holding an electrolytic solution, and the polymer is formed from a gel-forming monomer. A method for producing a secondary battery in which the above-described positive electrode and negative electrode are laminated in a flat plate via an electrolyte layer in which an electrolyte is held by a polymer derived from a gel-forming monomer and is derived from at least an active material. A step (A) of compression-molding an electrode preparation mixture containing a substance, an electrolytic solution and a gel-forming monomer on a current collector on the positive electrode and / or the negative electrode side; and a step (B) of polymerizing the gel-forming monomer. And, in the above step (A), a current collector is placed on the lower die surface using a compression molding die including a lower die and an upper die, and the shape is substantially similar to the current collector. Size and current collection 2. The secondary battery according to claim 1, wherein the electrode preparation mixture processed into a sheet, which is 30 to 90% of the body, is supplied to substantially the center of the current collector, and then compression molded. 3. Manufacturing method. 2. After each of the electrode preparation mixtures is compression-molded on the positive electrode side and the negative electrode side current collectors, an electrolytic solution and a gel-forming monomer are supported between the compression-molded electrode preparation mixtures. The method according to claim 1, further comprising a step of polymerizing the gel-forming monomer by heat-treating with the interposed sheet interposed.