WO2026018963A1 - Method for manufacturing all-solid-state secondary battery - Google Patents

Abstract

The present invention relates to a method for manufacturing an all-solid-state secondary battery. The present invention provides a method for manufacturing an all-solid-state secondary battery, the method comprising: a first step of preparing electrodes (1a) and (1b) that serve as a cathode (1a) and an anode (1b); a second step of forming solid electrolyte layers (2a) and (2b) on the surfaces of the cathode (1a) and the anode (1b); and a third step of obtaining a laminated device in which a separator (3) is disposed between the two electrodes (1a) and (1b) serving as the cathode (1a) and the anode (1b) on which the solid electrolyte layers (2a) and (2b) are formed, wherein the second step comprises the steps of: (1) obtaining a crosslink-polymerizable solid electrolyte solution containing an acrylic monomer, an ionic material, a crosslinking agent, a polymerization initiator, and a thickener; and (2) coating the surfaces of the cathode (1a) and the anode (1b) with the crosslink-polymerizable solid electrolyte solution, and then applying heat to perform crosslinking polymerization of the crosslinkable solid electrolyte solution to form solid electrolyte layers (2a) and (2b). According to the present invention, at least resistance characteristics can be improved.

Description

Manufacturing method of all-solid-state secondary battery

The present invention relates to a method for manufacturing an all-solid-state secondary battery, and more particularly, to a method for manufacturing an all-solid-state secondary battery, wherein when forming a solid electrolyte layer based on a polymer and an ionic substance (electrolyte) on an electrode (anode and cathode), a crosslinking polymerizable solid electrolyte solution of a specific component is used, and the crosslinking polymerizable solid electrolyte solution is coated on the electrode before crosslinking polymerization, and a solid electrolyte layer is formed by crosslinking polymerization after the coating, thereby improving at least the resistance characteristics.

Secondary batteries are garnering significant attention in the energy technology field. They are widely used as an energy source in devices such as mobile phones, laptops, unmanned aerial vehicles (drones), and electric vehicles, and research and development in this area are continuously increasing. Representative secondary batteries include lithium-ion secondary batteries, electric double-layer capacitors (EDLCs), and lithium-ion capacitors (LiCs).

A secondary battery comprises two electrodes, a positive electrode and a negative electrode, a porous separator formed (interposed) between the two electrodes to allow only the movement (conduction) of ions and prevent short circuits (insulation), and an electrolyte that allows the generation and movement of ions. The electrolyte is mainly a liquid electrolyte.

Liquid electrolytes are electrolyte solutions (commonly referred to as "electrolyte solutions") that dissolve (or dissociate) an electrolyte in a solvent. These have the advantage of high ion mobility, allowing ions to move freely within the solution. However, liquid electrolytes (electrolyte solutions) exist in a liquid state within secondary battery devices, and thus have a chronic problem of electrolyte leakage. If the electrolyte leaks externally, not only will the electrical properties deteriorate, but it can also cause contamination and skin damage, limiting their use in wearable devices that come into contact with the human body. Furthermore, liquid electrolytes can generate gases when used for long periods of time or exposed to high temperature/high humidity, which can increase the internal pressure of the secondary battery.

To improve this, all-solid-state secondary batteries using solid electrolytes instead of liquid electrolytes have been proposed. For example, secondary batteries using solid electrolytes are proposed in Korean Patent Publication No. 10-2024-0046136 (published on April 8, 2024), Korean Patent Registration No. 10-2108136 (registered on April 29, 2020), Korean Patent Registration No. 10-2678447 (registered on June 21, 2024), and Japanese Patent Publication No. 2000-138073. Generally, solid electrolytes comprise particulate polymers and ionic substances dispersed therein.

However, solid electrolytes, being polymer-based, do not pose a risk of leakage. However, they increase the thickness of the secondary battery. Furthermore, the polymer's crystallinity and complex molecular chain structure limit ion movement, resulting in low ion mobility. Consequently, most all-solid-state secondary batteries employing solid electrolytes have high internal resistance, making it difficult to achieve high output.

Accordingly, the present invention aims to provide a method for manufacturing an all-solid-state secondary battery in which at least the resistance characteristics can be improved by using a crosslinking polymerizable solid electrolyte solution composed of specific components, coating the crosslinking polymerizable solid electrolyte solution on an electrode before crosslinking polymerization, and forming a solid electrolyte layer by crosslinking polymerization after the coating.

In addition, the present invention provides a method for manufacturing an all-solid-state secondary battery, which can improve the electrical characteristics of an all-solid-state secondary battery by coating and drying an electrode slurry on a current collector to form an electrode active material layer, and by coating and drying using a multi-stage coating device that laminates a plurality of drying modules in the height direction and allows the coating material to move in a zigzag pattern while drying, thereby ensuring at least uniform drying.

In order to achieve the above purpose, the present invention,

Step 1: preparing electrodes (1a)(1b) of the positive electrode (1a) and the negative electrode (1b);

A second step of forming a solid electrolyte layer (2a)(2b) on the surface of the positive electrode (1a) and negative electrode (1b); and

A third step of obtaining a laminated element by interposing a separator (3) between two electrodes (1a) and (1b) of a positive electrode (1a) and a negative electrode (1b) on which the above solid electrolyte layer (2a) (2b) is formed,

The second step above is,

(1) a step of obtaining a crosslinkable polymerizable solid electrolyte solution comprising an acrylic monomer, an ionic substance, a crosslinking agent, a polymerization initiator, and a thickener; and

(2) A method for manufacturing an all-solid-state secondary battery is provided, including a step of coating the cross-linking polymerizable solid electrolyte solution on the surfaces of a positive electrode (1a) and a negative electrode (1b), and then applying heat to cross-link and polymerize the cross-linking polymerizable solid electrolyte solution to form a solid electrolyte layer (2a)(2b).

According to an embodiment of the present invention, the step of obtaining the crosslinking polymerizable solid electrolyte solution preferably comprises stirring and mixing 5 to 15 parts by weight of an ionic substance (electrolyte), 0.2 to 5 parts by weight of a crosslinking agent, 0.1 to 4 parts by weight of a polymerization initiator, and 0.2 to 5 parts by weight of a thickener with respect to 100 parts by weight of an acrylic monomer solution to obtain the crosslinking polymerizable solid electrolyte solution. At this time, the acrylic monomer solution preferably includes an acrylic monomer and a solvent, wherein the acrylic monomer includes at least one selected from acrylic acid, methacrylic acid, and salts thereof, and the crosslinking agent preferably includes a compound having both an epoxy group and a (meth)acrylate group in its molecule.

According to an embodiment of the present invention, the first step comprises:

(a) A first process of doping nitrogen into an electrode active material;

(b) a second process of obtaining an electrode slurry by mixing a conductive agent, a binder, and a solvent with the nitrogen-doped electrode active material; and

(c) a third process of coating and drying the electrode slurry on a current collector to form an electrode active material layer on the current collector;

The above first process is,

A step of immersing the above electrode active material in a nitrogen precursor solution; and

It may include a step of putting the electrode active material after the above immersion into a heating furnace and performing high-temperature heat treatment at a temperature of 400°C to 800°C for 30 minutes to 2 hours.

In addition, the third process,

A surface treatment step for treating the surface of the above-mentioned collector; and

It includes a coating/drying step of forming an electrode active material layer by coating and drying electrode slurry on the surface-treated surface of the above-mentioned collector,

The above surface treatment step is,

(i) Impurity removal step for removing impurities present on the surface of the entire body;

(ⅱ) A roughness forming step of forming surface roughness by immersing the entire body from which the above impurities have been removed in a perchloric acid solution containing perchloric acid and alcohol;

(ⅲ) an acid immersion treatment step in which the entire body having the above surface roughness formed is immersed in an acid solution; and

(ⅳ) It may include an oxidation layer forming step of forming an oxidation layer on the surface of the current collector immersed in the acidic solution. At this time, the oxidation layer forming step may be performed by immersing the current collector in an oxalic acid aqueous solution at a temperature of 80°C to 95°C, and then applying power for 5 to 20 minutes at a voltage of 2 to 10 V and a current density of 20 to 100 mA/cm2, with the current collector as the positive electrode (+) and the carbon body as the negative electrode (-).

According to an embodiment of the present invention, in the third process, it is preferable to use a coating device (10) capable of continuously performing coating and drying of electrode slurry.

At this time, the coating device (10) includes a drying module (300) that is stacked in multiple stages in the height direction, a supply unit (R1) that is arranged on one side of the drying module (300) and supplies a current collector, a coating module (CM) that forms a coating (S) by coating electrode slurry on the current collector supplied from the supply unit (R1), and a winding unit (R2) that is arranged on the other side of the drying module (300) and on which the dried coating (S) is wound.

According to an embodiment of the present invention, it has the effect of being able to implement high output with at least low resistance.

In addition, according to an embodiment of the present invention, the electrode active material layer is uniformly dried by a multi-stage coating device (10), which has the effect of improving electrical characteristics.

Figure 1 is a cross-sectional diagram of an all-solid-state secondary battery according to an embodiment of the present invention.

Figure 2 is a schematic diagram showing a conventional coating device that can be used in the present invention.

Figure 3 is a schematic diagram of a coating device according to an embodiment of the present invention.

FIG. 4 and FIG. 5 are perspective views showing a first transport unit that transports a coater in a specific direction among coating devices according to an embodiment of the present invention.

FIG. 6 is a partial perspective view showing the support and transport section of the first transport section of the coating device according to an embodiment of the present invention.

FIG. 7 and FIG. 8 are partial cross-sectional perspective views showing the front and upper portions of the housing of the first transfer unit of the coating device according to an embodiment of the present invention, respectively.

FIGS. 9 to 11 are perspective views showing a second transport unit of a coating device according to an embodiment of the present invention.

Figure 12 is a schematic diagram showing the operational relationship of the second transport unit of the coating device according to an embodiment of the present invention.

Fig. 13 is a perspective view showing a second power supply unit of a coating device according to an embodiment of the present invention.

The term "and/or" used in the present invention is used to mean including at least one or more of the components listed before and after. Terms such as "first" and "second" are used in the present invention to distinguish one component from another, and each component is not limited by these terms.

The present invention provides an all-solid-state secondary battery including a polymer solid electrolyte and a method for manufacturing the same. Fig. 1 shows a cross-sectional configuration of an all-solid-state secondary battery according to an embodiment of the present invention. Referring to Fig. 1, the all-solid-state secondary battery according to the present invention includes a positive electrode (1a); a negative electrode (1b); a separator (3) interposed between the positive electrode (1a) and the negative electrode (1b); and a solid electrolyte layer (2a) (2b), wherein the solid electrolyte layer (2a) (2b) includes a first solid electrolyte layer (2a) disposed between the positive electrode (1a) and the separator (3); and a second solid electrolyte layer (2b) disposed between the negative electrode (1b) and the separator (3).

In the present invention, the number of the positive electrode (1a), the negative electrode (1b), and the separator (3) is not limited, and they may be included one or two or more. The positive electrode (1a) and the negative electrode (1b) may be alternately laminated with the separator (3) therebetween. The solid electrolyte layer (2a) (2b) includes, according to the present invention, a cross-linked polymer having a network structure, and an ionic material uniformly dispersed and complexed in the cross-linked polymer. The solid electrolyte layer (2a) (2b) is formed by coating the positive electrode (1a) and the negative electrode (1b), and may exist in a form that penetrates the surface of the positive electrode (1a) and the negative electrode (1b), and the interior of the positive electrode (1a) and the negative electrode (1b).

The all-solid-state secondary battery according to the present invention is an electrochemical device capable of charging/discharging, and may be selected from, for example, a lithium ion battery, an electric double layer capacitor (EDLC), a lithium ion capacitor (LiC), a pseudo capacitor, and a hybrid capacitor. In addition, the all-solid-state secondary battery according to the present invention may be selected from a coin shape, a cylindrical shape (winding shape), a square shape (box shape), and a pouch shape, with no particular limitation on the shape or type thereof. According to one embodiment, the all-solid-state secondary battery according to the present invention may be a thin pouch shape, and may have a pouch-shaped exterior shape in which the positive electrode (1a), the negative electrode (1b), the separator (3), and the solid electrolyte layer (2a) (2b) are built into a pouch-shaped exterior case.

A method for manufacturing an all-solid-state secondary battery according to the present invention includes a first step of preparing electrodes (1a)(1b) of a positive electrode (1a) and a negative electrode (1b); a second step of forming a solid electrolyte layer (2a)(2b) on the surfaces of the positive electrode (1a) and the negative electrode (1b); and a third step of obtaining a laminated element having a separator (3) interposed between two electrodes (1a)(1b) of the positive electrode (1a) and the negative electrode (1b) on which the solid electrolyte layers (2a)(2b) are formed. The laminated element manufactured thus has a laminated structure of positive electrode (1a)/first solid electrolyte layer (2a)/separator (3)/second solid electrolyte layer (2b)/negative electrode (1b). According to the present invention, in the second step, a crosslinking polymerizable solid electrolyte solution is coated on the surfaces of the positive electrode (1a) and the negative electrode (1b), and then heat is applied to crosslink and polymerize the crosslinking polymerizable solid electrolyte solution to form a solid electrolyte layer (2a)(2b).

In addition, the method for manufacturing an all-solid-state secondary battery according to the present invention may further include a cell assembly step of embedding (accommodating) the laminated element obtained through the third step into an external case (pouch, etc.). The all-solid-state secondary battery according to the present invention may include one or two or more laminated elements of the positive electrode (1a)/first solid electrolyte layer (2a)/separator (3)/second solid electrolyte layer (2b)/negative electrode (1b) as one unit cell, and may include one or more of such unit cells. The plurality of unit cells may be electrically connected in series and/or in parallel.

Hereinafter, exemplary embodiments of the present invention will be described. In describing exemplary embodiments of the present invention, detailed descriptions of commonly known functions and/or configurations will be omitted. Furthermore, as a type of secondary battery, an electric double layer capacitor (hereinafter referred to as "EDLC") will be used as an example in some cases.

[1] Electrode preparation (Step 1)

In the present invention, the electrode (1a) (1b) is not particularly limited, and may be selected from various components depending on the type of secondary battery or the positive electrode (1a) and the negative electrode (1b). The electrode (1a) (1b) may include at least one selected from the following: an electrode active material, for example, a metal such as lithium (Li), aluminum (Al), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), cadmium (Cd), and/or zinc (Zn); a metal salt (metal oxide, etc.) containing at least one of these metals; and/or a carbon material such as activated carbon, graphite, graphitized carbon fiber, graphitized mesocarbon microbead, petroleum coke, hard carbon, soft carbon, carbon nanotube (CNT), graphene, and/or polyacene (polyacene semiconductor). The metal salt may be selected from, for example, lithium acid salts and silicon salts, and specific examples thereof include lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, and/or silicon oxide.

According to an embodiment of the present invention, the electrode (1a) (1b) may include a current collector in the form of a thin film and an electrode active material layer formed on the current collector. The current collector may be a metal thin film, for example, a metal foil composed of aluminum (Al), copper (Cu), lithium (Li), titanium (Ti), nickel (Ni) and/or an alloy thereof. The electrode active material layer may be formed by coating an electrode slurry containing an electrode active material, a conductive material, a binder and a solvent on the current collector.

The electrode active material may be selected from the metal oxides (such as lithium oxide and silicon oxide) and/or carbon materials (such as activated carbon and graphite) described above. In the case of EDLC, the electrode active material may include activated carbon as a main component. The activated carbon may be selected from powders having, for example, a specific surface area of 1500 to 2500 m2/g and an average particle size of 2 μm to 50 μm. In addition, the activated carbon may be selected from those carbonized and activated using, for example, resin-based materials such as phenol resins; plant-based materials such as coconut shells, apricot kernels, and rice husks; and/or coal/petroleum-based materials such as pitch cokes. In one embodiment, the activated carbon may be usefully used as coconut shell activated carbon, which is obtained by activating the carbonized product of coconut shells with steam (water vapor). In addition, commercialized products can be used, for example, YP series products (e.g., YP-50F and YP-80F, etc.).

The conductive material may be one that can improve electrical conductivity, and for example, a powder selected from carbon black such as acetylene black, graphite, graphene, carbon nanotubes (CNTs), and carbon nanofibers (CNFs); and/or oxides such as titanium oxide and ruthenium oxide may be used. The binder may be selected from polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), polyvinylpyrrolidone (PVP), acrylic acid, acrylic rubber, nitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), butyl rubber (BR), polyvinyl alcohol (PVA), and/or polyvinylacetate (PVAc). The solvent may be selected from water (distilled water, purified water, etc.) and/or a hydrocarbon-based organic solvent, etc. Examples of the hydrocarbon-based organic solvent include alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol; ketones such as methyl ethyl ketone (MEK); and/or N-methylpyrrolidone (NMP).

According to an embodiment of the present invention, the electrode preparation (first step) may include: (a) a first step of doping nitrogen (N) into an electrode active material; (b) a second step of obtaining an electrode slurry by mixing a conductive material, a binder, and a solvent into the electrode active material doped with nitrogen (N); and (c) a third step of coating and drying the electrode slurry onto a current collector to form an electrode active material layer on the current collector.

(a) First process (nitrogen doping)

The above first process is for doping nitrogen (N) onto the surface of a powdered electrode active material, and includes a step of immersing the electrode active material powder in a nitrogen precursor solution, and a step of putting the immersed electrode active material into a furnace and performing a high-temperature heat treatment. When the electrode active material is immersed in a nitrogen precursor solution and then subjected to a high-temperature heat treatment, nitrogen is doped onto the surface of the electrode active material, thereby increasing the specific surface area and improving the withstand voltage.

The above nitrogen precursor solution is a solution containing a nitrogen precursor and a solvent, and for example, a nitrogen precursor aqueous solution having a concentration of 10 to 40 wt% can be used. The nitrogen precursor is not particularly limited as long as it contains at least one nitrogen atom in the molecule, and may be selected from, for example, nitric acid (HNO ₃ ), lithium nitride (Li ₃ N), and/or lithium nitride phosphate (LiPON). The electrode active material can be immersed in the nitrogen precursor solution at room temperature for 10 minutes to 1 hour. After the electrode active material is immersed in the nitrogen precursor solution in the above manner, it is washed and dried, and then placed in a heating furnace (such as an electric furnace) to perform high-temperature heat treatment. At this time, the high-temperature heat treatment can be performed at a temperature in the range of 400°C to 800°C in an inert atmosphere for 30 minutes to 2 hours.

(b) Second process (electrode slurry manufacturing)

In the second process, an electrode slurry may be prepared by mixing 2 to 20 parts by weight of a conductive agent, 5 to 60 parts by weight of a binder, and 20 to 500 parts by weight of a solvent with respect to 100 parts by weight of an electrode active material. At this time, if the content of the conductive agent is less than 2 parts by weight, the improvement in electrical conductivity (i.e., improvement in internal resistance characteristics) due to its use is minimal, and if it exceeds 20 parts by weight, the electrostatic capacity may decrease. Considering this, the conductive agent may be used in an amount of 5 to 10 parts by weight with respect to 100 parts by weight of the electrode active material. The binder and the solvent may be used within the above weight range in consideration of adhesiveness and coating properties, respectively. The types of the electrode active material, conductive agent, binder, and solvent are as exemplified above.

(c) Third process (coating/drying)

In the third process, the electrode slurry manufactured as described above is coated on a current collector and then dried to manufacture a coated electrode having an electrode active material layer formed on the current collector. The current collector may use a metal foil as exemplified above. For example, the current collector may use an aluminum (Al) etching foil having an etched surface to provide a high surface area. In addition, in the third process, a coating device capable of continuously performing coating and drying of the electrode slurry may be used. Such a coating device will be described later. The coated electrode manufactured as described above may be used as a positive electrode and a negative electrode by performing a rolling process using a roll press and a slitting process for cutting into an appropriate size, as is typical. In this case, in the case of an EDLC, the positive electrode (1a) and the negative electrode (1b) may be configured in the same manner.

According to an embodiment of the present invention, the current collector may be surface-treated before being coated with electrode slurry. Specifically, the third process may include a surface treatment step of treating the surface of the current collector, and a coating/drying step of coating and drying the electrode slurry on the surface-treated surface of the current collector to form an electrode active material layer.

The above surface treatment step preferably includes, according to an embodiment of the present invention, (i) an impurity removal step, (ii) a roughness formation step, (iii) an acid immersion treatment step, and (iv) an oxide layer formation step. An example of each step is described below.

(ⅰ) Impurity removal step

First, impurities present on the surface of the current collector are removed. The impurity removal is to remove impurities such as solids (foreign substances) or oil present on the surface of the current collector, and includes a base/acid treatment. The base/acid treatment can be performed by immersing the current collector in a 10 to 40 wt% NaOH aqueous solution (at room temperature) for 1 to 10 minutes to degrease, then rinsing it with water, and then immersing it in a 10 to 40 wt% HNO ₃ aqueous solution (at room temperature) for 1 to 10 minutes.

(ⅱ) Illumination formation stage

The surface of the current collector from which the above impurities have been removed is roughened. The formation of the surface roughness can be carried out by a method of immersing the current collector in a perchloric acid solution containing perchloric acid (HClO ₄ ) and alcohol. More specifically, the roughness formation step can be carried out by immersing the current collector from which the impurities have been removed in a perchloric acid solution at about 20°C to 40°C and then stirring for 1 to 10 minutes. At this time, the perchloric acid solution can be an aqueous solution containing 10 to 30 wt% of perchloric acid (HClO ₄ ) and 20 to 60 wt% of ethanol.

(ⅲ) Acid immersion treatment step

The collector formed with the above roughness is immersed in an acidic solution. The acid immersion treatment can be performed by immersing in the acidic solution for 1 to 10 minutes. The acidic solution can be, for example, a 10 to 50 wt% HNO ₃ aqueous solution. When immersing in an acidic solution in this manner is advantageous for the formation of the oxide layer described below.

(ⅳ) Oxide layer formation stage

An oxide layer is formed on the surface of a current collector immersed in the above acidic solution. The formation of the oxide layer can be carried out by electrolytic method, and after immersing the current collector in an electrolytic solution at a temperature of about 80°C to 95°C, power is applied. At this time, during electrolysis, the current collector is used as the positive electrode (+). And, a carbon body such as a graphite rod can be used as the negative electrode (-). The electrolytic solution can use an oxalic acid aqueous solution having a concentration of 10 to 30 wt%. In addition, the electrolysis can be carried out by applying power for 5 to 20 minutes at a temperature of about 80°C to 95°C, a voltage of 2 to 10 V, and a current density of 20 to 100 mA/cm2. When an oxide layer is formed by the above electrolytic method, a microporous protective layer is formed on the surface of the current collector. For example, when Al etching foil is used as the current collector, a microporous Al oxide layer mainly composed of Al ₂ O ₃ can be formed.

Metal foils used as current collectors, such as Al etched foils, have excellent electrical conductivity, but they react with anions of the electrolyte, which can cause a drop in withstand voltage and corrosion. According to an embodiment of the present invention, when the surface is treated through the continuous progression of steps (i) to (iv) as described above, the reactivity with anions of the electrolyte is suppressed, thereby improving withstand voltage and preventing corrosion. In addition, the contact area and adhesion with the electrode active material layer are increased by the surface roughness and porous oxide layer, thereby improving electrical characteristics.

[2] Formation of solid electrolyte (second stage)

A solid electrolyte layer (2a) (2b) is formed on the surface of the electrode (1a) (1b). The solid electrolyte layer (2a) (2b) is a polymer-based polymer solid electrolyte, which may be in a solid or semi-solid gel form (gelation). According to the present invention, the formation of the solid electrolyte layer (2a) (2b) (second step) includes: (1) a step of obtaining a crosslinkable polymerizable solid electrolyte solution containing an acrylic monomer, an ionic substance, a crosslinking agent, a polymerization initiator, and a thickener; and a step of coating the crosslinkable polymerizable solid electrolyte solution on the surfaces of the positive electrode (1a) and the negative electrode (1b), and then applying heat to crosslink and polymerize the crosslinkable polymerizable solid electrolyte solution to form the solid electrolyte layer (2a) (2b).

(1) Preparation of cross-linked polymerizable solid electrolyte solution

The above crosslinkable polymerizable solid electrolyte solution can be obtained by stirring and mixing 5 to 15 parts by weight of an ionic substance, 0.2 to 5 parts by weight of a crosslinking agent, 0.1 to 4 parts by weight of a polymerization initiator, and 0.2 to 5 parts by weight of a thickener with respect to 100 parts by weight of an acrylic monomer solution. The acrylic monomer solution is a solution containing an acrylic monomer and a solvent, which can be obtained by stirring and mixing the acrylic monomer and the solvent at a weight ratio of 100:20 to 200 at room temperature for 30 minutes to 2 hours. The acrylic monomer may be, for example, acrylic acid, methacrylic acid, and/or a salt thereof. The salt is an acrylic metal salt in which a metal is bonded to an acrylic monomer (substituted with a metal ion), and examples thereof include an acrylic sodium salt, an acrylic potassium salt, and/or an acrylic lithium salt. The solvent may include, for example, water, alcohols, ketones, and/or N-methylpyrrolidone (NMP).

The above ionic material is a solid and/or liquid ionic compound that generates ions, and may be selected from electrolytes (electrolytic salts) commonly used in the art. The ionic material may be selected from ionic salts selected from inorganic substances, organic substances, and/or organic-inorganic composites. The ionic material may be, for example, a sulfide type such as Li ₂ S, P ₂ S ₅ , and Li ₂ SP ₂ S ₅ ; an oxide type such as Li ₇ La ₃ Zr ₂ O ₁₂ , Li ₁₄ Zn(GeO ₄ ) ₄ , and Na _1+x Zr ₂ SiP _3-x O ₁₂ (0≤x≤3); and/or a polymer type such as a polyethylene oxide type, a polypropylene oxide type, a polyvinylpyrrolidone type, and a polyalkylene sulfide type; etc. The ionic material may be, for example, a quaternary ammonium salt such as tetraethylammonium, triethylmethylammonium; (C ₂ H ₅ ) ₄ NBF ₄ and the like; aliphatic cyclic ammonium salts such as N-ethyl-N-methylpyrrolidinium and N,N-tetramethylene pyrrolidinium; quaternary imidazoles such as 1,3-dimethylimidazole and 1-ethyl-3-methylimidazole; and/or derivatives thereof, and specific examples thereof may include at least one selected from tetraethylammonium tetrafluoroborate, tetramethylammonium tetrafluoroborate, tetraphosphonium tetrafluoroborate, and tetraethylmethylammonium tetrafluoroborate.

The crosslinking agent may be any agent capable of crosslinking an acrylic monomer. The crosslinking agent may be selected from, for example, an amine compound; an ether compound; and/or an acrylate compound. Specific examples of the crosslinking agent include an amine compound such as triethylamine; an ether compound such as ethylene glycol methyl ether, ethylene glycol diglycidyl ether, and polyglycidyl ether; an acrylate compound such as N,N'-methylenebis(meth)acrylamide, (poly)ethylene glycol di(meth)acrylate, tetra(ethylene glycol) diacrylate, (polyoxyethylene) trimethylolpropane tri(meth)acrylate, and poly(meth)allyloxyalkane; a polyhydric alcohol compound such as propanediol, glycerin, and sorbitol; and/or an ionic polyhydric metal compound such as aluminum.

The crosslinking agent preferably includes a compound having both an epoxy group and a (meth)acrylate group in the molecule. According to a preferred embodiment of the present invention, when a multifunctional compound having both an epoxy group and a (meth)acrylate group is used as the crosslinking agent, a polymer crosslinked through the multifunctional compound can impart suitable strength to the polymer electrolyte layer (2a)(2b) due to good polymerization reactivity and/or crosslinking density. In addition, the crosslinking agent of the multifunctional compound has a three-dimensional network structure that is advantageous for the movement of ions, thereby improving electrical properties. The crosslinking agent of the multifunctional compound may further include other functional groups in the molecule in addition to the epoxy group and the (meth)acrylate group. Crosslinking agents of the above multifunctional compound include, for example, oxiran-2-ylmethyl methacrylate (or glycidyl methacrylate), oxiran-2-ylethyl methacrylate, and oxiran-2-ylpropyl methacrylate, and these may be used alone or in combination of two or more thereof as a crosslinking agent.

The above polymerization initiator is preferably one that can promote crosslinking polymerization of an acrylic monomer. The above polymerization initiator is a thermal polymerization initiator, and examples thereof include a persulfate-based initiator, an azo-based initiator, hydrogen peroxide, and/or ascorbic acid. Specific examples thereof include at least one selected from sodium persulfate, potassium persulfate, ammonium persulfate, 2,2-azobis-(2-amidinopropane)dihydrochloride, and 2,2-azobis-(N,N-dimethylene)isobutyramidine dihydrochloride.

The thickener is not limited as long as it provides viscosity to the crosslinked polymerizable solid electrolyte solution, and for example, one or more selected from among cellulose-based compounds and/or hydroxy-containing compounds can be used. Specific examples of the thickener include hydroxypropylmethylcellulose, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxymethylpropylcellulose, hydroxyethylhydroxypropylcellulose, ethylhydroxyethylcellulose, and/or methylhydroxypropylcellulose.

(2) Coating/crosslinking polymerization

The above crosslinking polymerizable solid electrolyte solution is coated on the surface of the electrode (1a) (1b), i.e., the surface of the electrode active material layer constituting each positive electrode (1a) and negative electrode (1b). After coating, heat is applied to perform crosslinking polymerization (thermal polymerization). The crosslinking polymerization can be performed, for example, by applying heat at a temperature of 60°C to 90°C for 30 minutes to 3 hours. By this crosslinking polymerization (thermal polymerization), a solid electrolyte layer (2a) (2b) is formed on the surface of the electrode (1a) (1b), and the solid electrolyte layer (2a) (2b) includes a crosslinking polymer and an ionic substance (electrolyte) dispersed and complexed in the crosslinking polymer.

The cross-linked polymer may have a three-dimensional network structure, which may include polymer chains of a scaffold structure connected in the x-axis, y-axis, and z-axis directions of a three-dimensional stereoscopic space, and a plurality of pores formed between the polymer chains. The polymer chains are composed of a cross-linked product of an acrylic monomer and a cross-linking agent, and/or a polymer of an acrylic monomer and a cross-linking agent. The pores have a microscopic size of micrometers (㎛), which may have a size of, for example, an average diameter of about 0.1 ㎛ to 50 ㎛, or 0.5 ㎛ to 40 ㎛. Due to the three-dimensional network structure of the cross-linked polymer, it may have at least ion mobility (ion conductivity). That is, ions generated from an ionic substance (electrolyte) can freely move (conduct) through the three-dimensional network structure of the cross-linked polymer. The ionic substance (electrolyte) is in a form bound to the polymer chains of the three-dimensional network structure; And/or can be dispersed and complexed in a form captured within the pores of a three-dimensional network structure.

The above coating can be performed by, for example, roll coating, knife coating, bar coating, and/or spray coating. The coating method is not particularly limited, but roll coating and/or knife coating can be performed to ensure uniform thickness and surface smoothness. The coating can be performed once or twice or more to obtain an appropriate thickness depending on the viscosity of the crosslinkable polymerizable solid electrolyte solution.

As mentioned above, according to the present invention, the coating is performed before crosslinking polymerization. When the crosslinking polymerizable solid electrolyte solution is coated before crosslinking polymerization, the solid electrolyte layer (2a) (2b) can be in maximum contact with the electrode (1a) (1b), and a well-developed three-dimensional network structure can be formed, thereby improving electrical characteristics. At this time, the solid electrolyte layer (2a) (2b) forms a layer with a predetermined thickness on the surface of the electrode (1a) (1b), and may have a thickness of, for example, 1 to 100 μm, 2 to 50 μm, or 5 to 20 μm, but is not limited thereto. In addition, a part of the solid electrolyte layer (2a) (2b) may exist in a form in which it has penetrated into the electrode active material layer of the electrode (1a) (1b).

Meanwhile, a method of crosslinking and polymerizing the above-mentioned crosslinkable polymerizable solid electrolyte solution and then coating it on the electrode (1a) (1b) can be considered, but in this case, the crosslinked polymerized resin is in the form of solid particles, which reduces the coatability, and a separate binder must be added during coating for adhesion to the electrode (1a) (1b). This causes difficulties in the process due to the reduction in coatability and the addition of the binder, and above all, ion mobility may decrease.

In contrast, according to the present invention, when the crosslinking polymerizable solid electrolyte solution is first coated on the electrode (1a) (1b) before crosslinking polymerization and then crosslinking polymerization is performed, sufficient adhesiveness with the electrode (1a) (1b) is achieved without using a separate binder, and a well-developed three-dimensional network structure is formed, resulting in high ion mobility. Accordingly, low resistance characteristics are achieved. In addition, the crosslinking polymer is crosslinked and polymerized on the surface of the electrode (1a) (1b), so that the solid electrolyte layer (2a) (2b) is bonded to the electrode (1a) (1b) in a state of maximum adhesion. In addition, the solution before crosslinking polymerization can be coated on the electrode (1a) (1b) with a thin thickness, thereby enabling the formation of a thin film of the solid electrolyte layer (2a) (2b), i.e., a thin film of an all-solid-state secondary battery.

[3] Manufacturing of laminated elements (Stage 3)

A laminated element is obtained by interposing a separator (3) between two electrodes (1a)(2b) of the positive electrode (1a) and the negative electrode (1b). At this time, the laminated element is configured to have a laminated structure of positive electrode (1a)/first solid electrolyte layer (2a)/separator (3)/second solid electrolyte layer (2b)/negative electrode (1b). That is, the solid electrolyte layers (2a)(2b) formed on each electrode (1a)(2b) are laminated so as to be in contact with the separator (3).

The above-described laminated element can be compressed for thin film formation, and a separator (3) is interposed to prevent a short circuit between the electrodes (1a) and (2b), which may be a concern. The separator (3) is an insulating porous member, and may be, for example, a non-woven fabric (or fabric) selected from polyethylene (PE), polypropylene (PP), and/or cellulose, or a glass fiber non-woven fabric. The separator (3) may be, for example, a porous film selected from polyethylene (PE) and/or polypropylene (PP).

In addition, the laminated element manufactured as described above can be embedded in an external case. The laminated element can be embedded in the external case one or more times, and after the embedded element is compressed to make it thinner. The external case can be selected from a coin shape, a cylindrical shape, a square shape (box shape), a pouch shape, etc. According to one embodiment, the external case can use a pouch-type external case. When such a pouch-type external case is used, for example, a slim and compact thin EDLC can be implemented.

According to the present invention described above, a crosslinkable polymerizable solid electrolyte solution containing an acrylic monomer, an ionic substance, a crosslinking agent, a polymerization initiator, and a thickener is used, and the crosslinkable polymerizable solid electrolyte solution is first coated on an electrode (1a)(1b) before crosslinking polymerization, and then crosslinking polymerization is performed after the coating to form a solid electrolyte layer (2a)(2b), whereby at least the resistance characteristics can be improved. In addition, the solid electrolyte layer (2a)(2b) can be formed into a thin film by coating.

Meanwhile, in the third process, a coating device for coating and drying the electrode slurry can continuously perform the coating process and the drying process, and this can utilize, for example, an existing coating device as shown in Fig. 2. Referring to Fig. 2, the coating device may include a supply unit (R1) on which a current collector is wound, a coater (C) for coating by spraying electrode slurry on a current collector supplied by being unwound from the supply unit (R1), a drying unit (DD) for drying the coating (S) coated by the coater (C), and a winding unit (R2) for winding the coating (S) dried in the drying unit (DD).

The above coating device preferably utilizes a multi-stage coating device described below according to an embodiment of the present invention. Hereinafter, a multi-stage coating device according to an embodiment of the present invention will be described with reference to the attached FIGS. 3 to 13. The thickness of lines and the sizes of components depicted in the drawings may be exaggerated for clarity and convenience of explanation. The coating device described below is presented in Korean Patent Application No. 10-2024-0081662 (filing date: June 24, 2024) proposed by the present applicant.

Referring to FIGS. 3 to 13, a coating device (10) according to an embodiment of the present invention includes a drying module (300) that is stacked in multiple stages in the height direction (up-down direction) of the coating device (10), a supply unit (R1) that is arranged on one side of the drying module (300) to supply a current collector, a coating module (CM) that forms a coating (S) by coating electrode slurry on the current collector supplied from the supply unit (R1), and a winding unit (R2) that is arranged on the other side of the drying module (300) to wind the dried coating (S). At this time, the coating (S) is coated by the coating module (CM), and includes a current collector and an electrode active material layer formed by coating electrode slurry on the current collector. The current collector is a metal thin film, and as described above, an example thereof may be aluminum foil (Al foil). The above coating module (CM) is disposed between the supply unit (R1) and the drying module (300) to coat the electrode slurry on the current collector. The coating module (CM) is disposed on one side (left side in FIG. 2) of the drying module (300) and includes one or more coaters (C) that coat the electrode slurry. The electrode slurry is coated to an appropriate thickness by the coater (C), and since the coater (C) itself has a well-known configuration, a detailed description and illustration thereof will be omitted. In addition, the coater (C) can be fixed and supported by a structure (A) disposed on one side of the drying module (300), and since the structure (A) also has a general configuration, a detailed description and illustration thereof will be omitted.

The above drying module (300) includes a plurality of module cases (310) arranged in multiple stages in the height direction, a plurality of rollers (320) provided on the inner and outer sides of the module cases (310) to transport the coating material (S), and a plurality of drying units (DD) arranged inside the module cases (310) to dry the coating material (S). The plurality of rollers (320) are provided in multiple numbers in the up, down, left, and right directions so that the coating material (S) is transported in multiple stages in the height direction while repeatedly advancing and retreating in the horizontal direction.

That is, a plurality of module cases (310) are stacked in multiple layers in the height direction, and a plurality of rollers (320) are provided on the inner and outer sides of the module cases (310) in the vertical height direction and the left and right horizontal direction. To this end, a structure (not shown) having a first layer (F1) and a second layer (F2) arranged in the height direction may be included. The structure may be a horizontal structure arranged in a horizontal direction inside a building and arranged in multiple layers in the height direction. At this time, an opening (F2-1) may be formed in a part of the upper layer (F2) to allow the coating (S) to move, which will be described separately.

The above coating (S) is transported by a plurality of rollers (320), and the plurality of rollers (320) are provided on the inside and outside of the module case (310) so that the coating (S) is arranged in multiple layers in the height direction while repeatedly advancing and retreating in the horizontal direction.

To be more specific, module cases (310-1, 310-2) are respectively arranged on multiple layers (F1, F2) arranged in the height direction of the coating device (10). As in the embodiment illustrated in FIG. 3, it is also possible to arrange the second module case (310-2) and the first module case (310-1) on the second layer (F2) and the first layer (F1), respectively. A plurality of rollers (320) are arranged inside the second module case (310-2) arranged on the second layer (F2), and a plurality of rollers (320) are also arranged inside the first module case (310-1) arranged on the first layer (F1). By these rollers (320), the coating (S) moves to the right side in the drawing inside the second module case (310-2) and then moves to the left side again. Afterwards, the coating material (S) is discharged from the second module case (310-2) and then passes through the opening (F2-1) to the first module case (310-1) of the first layer (F1). At this time, a plurality of rollers (320) are also arranged in the opening (F2-1) to direct the coating material (S) from the second module case (310-2) to the first module case (310-1).

The coating material (S) that entered the first module case (310-1) also moves to the right side in the drawing and then to the left side again, and is finally wound on the winding unit (R2). More specifically, the coating material (S) is dried while moving in a zigzag manner in the left-right direction in the drawing through a plurality of rollers (320). The coating device (10) according to the embodiment of the present invention shown in FIG. 3 can have a space for drying smaller than that of the related art (FIG. 2). In addition, according to the present invention, since the drying modules (300) are stacked in the height direction, heat transfer between them is more efficient and concentrated than that of the related art long drying unit, so that uniform drying can be realized, and thereby the electrical characteristics of the battery can be improved.

A drying unit (DD) is provided inside the above module case (310) to dry the coated material (S) on which the coating has been completed. This drying unit (DD) can utilize a widely known microwave oven, infrared (IR) lamp, and/or hot air generator.

Meanwhile, since the roller (320), supply section (R1) and winding section (R2) can utilize conventional technology, redundant description and illustration thereof are omitted.

A coating module (CM) is arranged on one side of the drying module (300). At this time, the coating module (CM) may include a first transport unit (100) for adjusting the horizontal position of the coater (C). As illustrated in FIG. 4, when the coating material (S) moves in the left-right direction (direction 1) in the drawing, the coater (C) is transported in the horizontal direction, i.e., the width direction, by the first transport unit (100), thereby realizing a uniform coating.

The first transfer unit (100) may include a plate-shaped base (110) fixed to one outer side of the inside of the module case (310), a housing (150) fixed to the base (110), and a moving block (160) movably provided on one side of the housing (150) and on which a coater (C) is loaded. At this time, a transfer unit (170) is provided inside the housing (150) to move the moving block (160). A coater (C) is mounted on the moving block (160), and the moving block (160) and the coater (C) can be transferred by the transfer unit (170).

Meanwhile, the base (110) can be fixed to a structure (A) on which the coating module (CM) is installed, and the configuration for fixing the base (110) and the structure (A) is a widely known technology, so a detailed description and illustration thereof are omitted.

A first power supply unit (120) is fixed and installed on one side of the above base (110) to supply rotational power. A first shaft (SH1) is provided on this first power supply unit (120) to rotate. The transfer unit (170) is driven by the first shaft (SH1), and for this purpose, a power transmission unit (130) is provided between the first shaft (SH1) and the transfer unit (170) to transmit rotational power to the transfer unit (170).

That is, the first power supply unit (120) can use a widely known electric motor, etc., and the rotational power generated in the first power supply unit (120) drives the transport unit (170) through the first shaft (SH1) and the power transmission unit (130). Meanwhile, the first power supply unit (120) can use a widely known electric motor, etc., and since such an electric motor is a widely known configuration, a detailed description and illustration are omitted.

The above-described transfer unit (170) includes a cylindrical transfer unit body (1710) and a spiral groove (1720) that is arranged in a spiral shape on the outer surface of the transfer unit body (1710) and is recessed to a specific depth. Support rings (1730) are provided on both ends of the transfer unit body (1710) to rotatably support the transfer unit body (1710) within the housing (150). The support ring (1730) may include a widely known bearing, etc., and since this configuration is widely known, a detailed description and illustration thereof will be omitted.

The above-described coater (C) is loaded onto a moving block (160), and the moving block (160) is movably provided on one side of a housing (150). The housing (150) includes a housing body (1510) having a hollow shape and open on both sides in the longitudinal direction of the transfer unit body (1710), and a support (1520) disposed inside the housing body (1510) and supporting the transfer unit body (1710). The support (1520) supports the bottom surface of the moving unit body (1710), and may be formed to have a groove that matches the curvature of the moving unit body (1710) in order to support it more stably.

Meanwhile, since the above-mentioned coater (C) is also a widely known configuration, it is briefly indicated by a broken line in Fig. 4.

A first guide (1540) is provided on the upper surface of the housing body (1510). This first guide (1540) is arranged along the movement direction of the moving block (160). An open slot (1550) is formed on one side of the first guide (1540), and the open slot (1550) is arranged along the first guide (1540) and has a shape that opens to a certain width. The first guides (1540) may be provided as a pair, and the open slot (1550) may be formed between the pair of guides (1540).

The above moving block (160) includes a moving block body (1610) having a plate shape. A coater (C) is mounted on the moving block body (1610). A linkage bar (1620) is provided to extend downward on the lower surface of the moving block body (1610). The linkage bar (1620) passes through an open slot (1550) and is then inserted into a spiral groove (1720) of a transfer unit body (1710). That is, when the transfer unit body (1710) rotates, the linkage bar (1620) inserted into the spiral groove (1720) moves forward and backward, thereby moving the moving block body (1610) forward and backward. Protrusions (1630) are formed on both ends in the width direction of the moving block body (1610). The above protrusion (1630) is bent downward and is connected to the first guide (1540) in a male and female manner.

As described above, the linkage bar (1620) penetrates the open slot (1550) of the housing body (1510) and is inserted into the spiral groove (1720). At this time, the transfer unit body (1710) in which the spiral groove (1720) is formed is supported by the support member (1520), and the side of the transfer unit body (1710) facing the power transmission unit (130) is exposed from the housing (150) and then linked to the power transmission unit (130). At this time, the exposed transfer unit body (1710) is supported by the support member (140). The support member (140) includes a support member body (1410) installed on the base (110) and a through hole (1420) formed in the support member body (1410) and into which the transfer unit body (1710) is rotatably inserted. The transfer unit body (1710) is stably supported by this support member (140) and connected to the power transmission unit (130).

The power transmission unit (130) may include a first gear (1310) provided on the first shaft (SH1), and a second gear (1320) coupled with the first gear (1310) and interlocked with the transfer unit body (1710). The first gear (1310) and the second gear (1320) may use a worm wheel and a worm gear, as illustrated. Since these gears are widely known configurations, a description thereof will be omitted.

The operation process of the first transfer unit (100) described above will be described again. First, the first power supply unit (120) generates rotational force to rotate the first shaft (SH1). When the first shaft (SH1) rotates, the first gear (1310) rotates, thereby rotating the second gear (1320). When the second gear (1320) rotates, the transfer unit body (1710) rotates. At this time, since the linkage bar (1620) is inserted into the spiral groove (1720) formed in the rotating transfer unit body (1710), the linkage bar (1620) moves forward and backward by the rotation of the transfer unit body (1710), thereby moving the moving block (160) forward and backward. Since the coater (C) is loaded on the moving block (160), the coater (C) ultimately moves, thereby adjusting the horizontal position. That is, the horizontal position of the coater (C) is adjusted according to the degree of rotation and direction of rotation of the transport unit body (1710) based on the degree of rotation and direction of rotation of the first power supply unit (120). The degree of rotation (number of rotations, etc.) and direction of rotation (forward and reverse rotation) of the first power supply unit (120) can be adjusted manually or by a control unit (not shown) that controls the first power supply unit (120).

The horizontal position of the coater (C) is adjusted by the first transfer unit (100), but according to another embodiment, the height position of the coater (C) can also be adjusted. To this end, the coating device (10) may further include a second transfer unit (200) that moves the coater (C) forward and backward in the direction of the coating material (S). That is, the second transfer unit (200) adjusts the height position of the coater (C) by moving the coater in the vertical direction in the drawing. This second transfer unit (200) may be provided in the moving block (160).

The second transport unit (200) includes a second power supply unit (220) provided on one side of the moving block (160) to generate forward and backward power, a pair of guide plates (210) vertically arranged on the moving block (160), a coater lifting unit (250) coupled to the guide plate (210) to be raised and lowered, and a pair of link units (LN) rotatably provided by being pin-coupled to the coater lifting unit (250). The pair of link units (LN) are respectively arranged on both sides (LN-1, LN-2) in the width direction of the coater lifting unit (250). A coater (C) may be arranged on the coater lifting unit (250).

The above link unit (LN) may include a first link (230) and a second link (240) that are spaced apart from each other at a predetermined interval in the longitudinal direction of the coater raising/lowering unit (250). The upper end of the first link (230) or the second link (240) is moved forward and backward by the second power supply unit (220). The second power supply unit (220) may utilize a widely known hydraulic or pneumatic cylinder, and since the configuration of such a cylinder is a widely known technology, a detailed description and illustration are omitted. The second power supply unit (220) may be selectively linked to the first link (230) or the second link (240), and may also be linked to both the first link (230) and the second link (240).

The first link (230) includes a first link body (2310) having a shape bent at a specific angle, a first moving block (2320) pin-coupled to the lower end of the first link body (2310), and a first guide block (2330) positioned on the moving block (160) to guide the movement of the first moving block (2320). The first guide block (2330) is fixed to the moving block (160), and the first moving block (2320) can be male-female coupled to the first guide block (2330).

To this end, the first moving block (2320) may include a U-shaped first moving block body (2321) and an insertion pin (2322) connecting the first moving block body (2321). The first link body (2310) is pin-coupled to the insertion pin (2322). The first guide block (2430) may have a U-shape, but the upper end may be bent inward to prevent the first moving block body (2321) from being detached.

The second link (240) includes a second link body (2410) having a symmetrical shape with the first link body (2310), a second moving block (2420) pin-coupled to the lower end of the second link body (2410), and a second guide block (2430) arranged on the moving block (160) to guide the movement of the second moving block (2420), and the second moving block (2420) is male-female coupled to the second guide block (2430). The second moving block (2420) may also include a second moving block body (2421) having a U-shape, and an insertion pin (2422) connecting the second moving block body (2421). The second link body (2410) is pin-coupled to the insertion pin (2422). In addition, the second guide block (2430) may also have a U-shape, but the upper end may be bent inward to prevent the second moving block body (2421) from being detached.

The guide plate (210) is placed between the first guide block (2330) and the second guide block (2430), and the raising and lowering of the coater raising and lowering unit (250) is guided by the guide plate (210).

By this configuration, the upper part of the first link (230) is moved forward or backward by the second power supply unit (220), and thereby the coater lifting/lowering unit (250) is combined with the guide plate (210) to be raised/lowered, and at the same time, the second link (240) is operated in the opposite direction to the first link (230), which will be described separately.

The above-mentioned cotter elevating/lowering unit (250) may include a pair of elevating/lowering plates (2510) spaced apart in the width direction of the moving block (160) and a connecting bar (2520) connecting the pair of elevating/lowering plates (2510). As illustrated in Fig. 13, a cotter (C) may be arranged on the connecting bar (2520).

The above-mentioned lifting plate (2510) includes a lifting plate main body (2511) in the shape of a plate, a guide protrusion (2512) extending upwardly from the upper side of the lifting plate main body (2511), and a protruding pin (2514) protruding from the lifting plate main body (2511) and pin-connecting the first link (230) and the second link (240). At this time, a guide groove (2513) is formed in the lifting plate main body (2511) and the guide protrusion (2512) in the lifting and lowering direction. The protruding pin (2514) can be respectively coupled to the through hole (2311) of the first link (230) and the through hole (2411) of the second link (240).

By this configuration, the first link (230) and the second link (240) are pin-connected to the lifting plate body (2411), and the lifting plate body (2511) is raised and lowered by the forward and backward movement of the first link (230). In addition, the second link (240) is operated in the opposite direction to the first link (230) in conjunction with the raising and lowering of the lifting plate body (2511).

At this time, a guide plate (210) is coupled to the guide groove (2513) of the main body (2511) of the lifting/lowering plate. Accordingly, the main body (2511) of the lifting/lowering plate is guided to move up and down by the guide plate (210), thereby realizing stable movement, and the coater (C) moves forward and backward toward the coating material (S) by the moving up and down of the main body (2511) of the lifting/lowering plate.

Referring again to FIG. 12, when the upper part of the first link (230) moves to the left in the drawing by the second power supply unit (220) (not shown in FIG. 12) as shown in FIG. 12(a), the first link (230) rotates counterclockwise. Accordingly, the first moving block (2320) moves to the right in the drawing, and the elevating plate body (2511) is lowered. At this time, the elevating plate body (2511) is lowered while being coupled to the guide plate (210), thereby realizing a stable descent. Meanwhile, due to the descent of the elevating plate body (2511), the second link (240) rotates in the opposite direction, clockwise, and the second moving block (2420) moves to the left in the drawing.

As shown in Fig. 12(b), when the upper part of the first link (230) moves to the right in the drawing by the second power supply unit (220) (not shown in Fig. 12), the first link (230) rotates clockwise and the first moving block (2320) moves to the left in the drawing. With this configuration, the elevating plate body (2511) rises. At this time, as described above, the elevating plate body (2511) moves while being coupled to the guide plate (210), so that a stable rise is realized. In addition, the second link (240) rotates counterclockwise by the rising of the elevating plate body (2511), and the second moving block (2420) moves to the right in the drawing.

As shown in Fig. 12(c), if the first link (230) is additionally moved to the right in the drawing, the first link (230) additionally rotates clockwise, causing the lifting plate body (2511) to additionally rise. In addition, the second link (240) also additionally rotates clockwise.

As described above, the main body (2511) of the lifting plate is raised and lowered by the forward and backward movement of the first link (230), and thereby the coater (C) is raised and lowered in the direction of the coating material (S), thereby adjusting the height position of the coater (C).

At this time, the first link (230) is moved forward and backward by the second power supply unit (220), and the second power supply unit (220) may use a hydraulic or pneumatic cylinder as described above. This second power supply unit (220) may include a power generation unit (2210) that generates forward and backward power as illustrated in FIG. 13, and an operating rod (2220) that moves forward or backward by the power generation unit (2210). At this time, since the angle of the second power supply unit (220) changes due to the rotation of the first link (230), in order to respond to this, a bracket (2340) and a connecting pin (2350) may be formed on the first link (230), and then the operating rod (2220) may be pin-coupled to the connecting pin (2350). Meanwhile, the power generation unit (2210) may be supported by a general support unit (260), and at this time, the power generation unit (2210) may be pin-coupled with the support unit (260) to respond to the angle change of the first link (230).

Hereinafter, specific experimental examples of the present invention will be provided. The following examples are provided solely as examples to aid understanding of the present invention and are not intended to limit the technical scope of the present invention.

[Example 1]

1. Surface treatment of the entire house

An Al etching foil with a thickness of approximately 20 μm was prepared as a current collector, and was first degreased by immersing it in a 15 wt% NaOH aqueous solution (room temperature) for 5 minutes, and then rinsed with water. Subsequently, it was immersed in a 15 wt% HNO ₃ aqueous solution (room temperature) for 5 minutes and rinsed with water. Next, in order to form surface roughness on the Al etching foil, it was immersed in a perchloric acid solution containing 15 wt% perchloric acid (HClO ₄ ) and 30 wt% ethanol. The immersion was performed at a temperature of approximately 30°C for 5 minutes to form surface roughness. After the formation of the surface roughness, it was rinsed with distilled water, immersed in a 30 wt% HNO ₃ aqueous solution for 5 minutes, rinsed with distilled water, and then dried.

Next, for the Al etching foil that had undergone surface roughening and HNO ₃ immersion treatment as described above, the Al etching foil (current collector) and graphite rod (carbon body) were impregnated in an electrolytic cell containing a 15 wt% oxalic acid aqueous solution, and then the Al etching foil (current collector) was connected to the positive electrode (+) and the graphite rod (carbon body) was connected to the negative electrode (-). Then, the temperature of the oxalic acid aqueous solution was maintained at approximately 90°C, and power was applied at a voltage of 5 V and a current density of 50 mA/cm2 for approximately 10 minutes to form an oxide layer (oxide film) on the surface of the Al etching foil.

2. Electrode manufacturing

Activated carbon was used as an electrode active material. First, the activated carbon was immersed in an approximately 20 wt% HNO ₃ aqueous solution at room temperature for 30 minutes, then washed with distilled water and dried. Thereafter, the activated carbon was placed in an electric furnace and heat-treated at a temperature of approximately 550°C for 1 hour. Afterwards, a solvent (NMP) was added to a mixer equipped with a stirrer, activated carbon and a binder were added, and a stirred solution was obtained by mixing them. Then, carbon black was added as a conductive material and thoroughly mixed to prepare an electrode slurry. At this time, the activated carbon was activated carbon from coconut charcoal, and the binder was carboxymethyl cellulose (CMC). During the mixing process, the weight ratio of activated carbon: conductive material: binder was approximately 90:10:8.

The electrode slurry was coated on the surface-treated Al etching foil, dried, and then pressed with a roll press at about 120°C to form an electrode sheet having an electrode active material layer of about 40 μm in thickness.

3. Formation of solid electrolyte layer / EDLC cell manufacturing

An acrylic acid solution was placed in a mixer equipped with a stirrer, and about 7.5 parts by weight of an ionic substance (electrolyte), about 1.2 parts by weight of a crosslinking agent, about 0.8 parts by weight of a polymerization initiator, and about 2.5 parts by weight of a thickener were mixed with respect to 100 parts by weight of the acrylic acid solution to obtain a crosslinkable polymerizable solid electrolyte solution. At this time, the acrylic acid solution was used in a mixture of about 55.5 parts by weight of distilled water with respect to 100 parts by weight of acrylic acid. The ionic substance (electrolyte) was used in a mixture of tetraethylammonium and tetraethylammonium tetrafluoroborate in a weight ratio of 1:1, and the crosslinking agent was used as a polyfunctional compound having both an epoxy group and a (meth)acrylate group in the molecule, and glycidyl methacrylate was used as the crosslinking agent. In addition, ammonium persulfate was used as the polymerization initiator, and hydroxyethyl cellulose was used as the thickener.

Next, the cross-linkable polymerizable solid electrolyte solution was roll-coated onto the electrode active material layer of the electrode sheet to form a coating layer. Thereafter, heat was applied at a temperature of about 75°C for 1 hour to cross-link and polymerize. Through this, an electrode coating body was manufactured in which a solid electrolyte layer having a thickness of about 18 μm was formed on one side of the electrode sheet. The electrode coating body was cut into multiple pieces, and a cathode-side coating body and anode-side coating body were prepared. Then, a lead terminal made of Al was attached to the current collector of each electrode. Thereafter, a separator (PE non-woven fabric) was interposed between the cathode-side coating body and the anode-side coating body, and then the resultant was placed in a pouch to manufacture an all-solid-state EDLC cell specimen.

[Example 2]

In comparison with Example 1 above, the current collector used in the electrode fabrication and the crosslinking agent used in the crosslinking polymerizable solid electrolyte solution fabrication were different. The current collector used an untreated Al etched foil, and the crosslinking agent used was an amine-based triethylamine.

[Electrical Characteristics Evaluation]

For the EDLC cell specimens according to each of the above examples, the internal resistance and initial capacity at 2.7 V were evaluated using a conventional method. The results are shown in [Table 1] below.

< Electrical Characteristics Evaluation Results of EDLC Cell Specimens > note Whole house crosslinking agent internal resistance
[Ω] Initial capacity
[F] Example 1 Surface treated glycidyl methacrylate 0.72 0.127 Example 2 Untreated surface triethylamine 0.64 0.124

As shown in the above [Table 1], it was found that the electrical characteristics of the EDLC cell specimens varied depending on the current collector and cross-linking agent. As in Example 1, it was found that when the current collector was surface-treated and a multifunctional compound (glycidyl methacrylate) having both an epoxy group and a (meth)acrylate group was used as the cross-linking agent, the initial capacity was high and the internal resistance was low.

Claims (4)

Step 1: preparing electrodes (1a)(1b) of the positive electrode (1a) and the negative electrode (1b); A second step of forming a solid electrolyte layer (2a)(2b) on the surface of the positive electrode (1a) and negative electrode (1b); and A third step of obtaining a laminated element by interposing a separator (3) between two electrodes (1a) and (1b) of a positive electrode (1a) and a negative electrode (1b) on which the above solid electrolyte layer (2a) (2b) is formed, The second step above is, (1) a step of obtaining a crosslinkable polymerizable solid electrolyte solution comprising an acrylic monomer, an ionic substance, a crosslinking agent, a polymerization initiator, and a thickener; and (2) A method for manufacturing an all-solid-state secondary battery, characterized by including a step of coating the cross-linking polymerizable solid electrolyte solution on the surfaces of the positive electrode (1a) and the negative electrode (1b), and then applying heat to cross-link and polymerize the cross-linking polymerizable solid electrolyte solution to form a solid electrolyte layer (2a)(2b). In the first paragraph, The step of obtaining the above crosslinking polymerizable solid electrolyte solution is to obtain a crosslinking polymerizable solid electrolyte solution by stirring and mixing 5 to 15 parts by weight of an ionic substance, 0.2 to 5 parts by weight of a crosslinking agent, 0.1 to 4 parts by weight of a polymerization initiator, and 0.2 to 5 parts by weight of a thickener with respect to 100 parts by weight of an acrylic monomer solution. The above acrylic monomer solution comprises an acrylic monomer and a solvent, wherein the acrylic monomer comprises at least one selected from acrylic acid, methacrylic acid, and salts thereof. A method for manufacturing an all-solid-state secondary battery, characterized in that the crosslinking agent comprises a compound having both an epoxy group and a (meth)acrylate group in the molecule. In the first paragraph, The above first step is, (a) A first process of doping nitrogen into an electrode active material; (b) a second process of obtaining an electrode slurry by mixing a conductive agent, a binder, and a solvent with the nitrogen-doped electrode active material; and (c) a third process of coating and drying the electrode slurry on a current collector to form an electrode active material layer on the current collector; The above first process is, A step of immersing the above electrode active material in a nitrogen precursor solution; and It includes a step of putting the electrode active material after the above immersion into a heating furnace and performing high-temperature heat treatment at a temperature of 400°C to 800°C for 30 minutes to 2 hours. The third process above is, A surface treatment step for treating the surface of the above-mentioned collector; and It includes a coating/drying step of forming an electrode active material layer by coating and drying electrode slurry on the surface-treated surface of the above-mentioned collector, The above surface treatment step is, (i) Impurity removal step for removing impurities present on the surface of the entire body; (ⅱ) A roughness forming step of forming surface roughness by immersing the entire body from which the above impurities have been removed in a perchloric acid solution containing perchloric acid and alcohol; (ⅲ) an acid immersion treatment step in which the entire body having the above surface roughness formed is immersed in an acid solution; and (ⅳ) including an oxide layer forming step of forming an oxide layer on the surface of the collector immersed in the acidic solution, A method for manufacturing an all-solid-state secondary battery, characterized in that the above-mentioned oxide layer forming step is performed by immersing the current collector in an oxalic acid aqueous solution at a temperature of 80°C to 95°C, and then applying power for 5 to 20 minutes at a voltage of 2 V to 10 V and a current density of 20 to 100 mA/cm2, with the current collector as the positive electrode (+) and the carbon body as the negative electrode (-). In the third paragraph, In the third process, a coating device (10) capable of continuously performing coating and drying of electrode slurry is used. A method for manufacturing an all-solid-state secondary battery, characterized in that the coating device (10) comprises a drying module (300) that is stacked in multiple stages in the height direction, a supply unit (R1) that is arranged on one side of the drying module (300) and supplies a current collector, a coating module (CM) that forms a coating (S) by coating electrode slurry on the current collector supplied from the supply unit (R1), and a winding unit (R2) that is arranged on the other side of the drying module (300) and winds the dried coating (S).