Method for manufacturing a conductive polymer inorganic solid electrolyte secondary battery

Abstract

A method for manufacturing a conductive polymer solid electrolyte secondary battery through the following steps: step (I) of manufacturing a positive electrode having a close-packed structure with a pore filling rate of 70% or more, which is a combination of an active material, a conductive material, and an ion-conductive binder; step (II) of impregnating and / or surface-coating the positive electrode obtained in step (I) with a conductive polymer solution; step (III) of manufacturing a positive electrode by either blending an inorganic solid electrolyte with the conductive polymer solution to the positive electrode obtained in step (II) to form a casting slurry, coating the surface, and molding the positive electrode and the cathode together, or by forming a conductive polymer solid electrolyte membrane and pressing it into a two-layered mold; processing step (IV) of heating the positive electrode having the conductive polymer and inorganic solid electrolyte obtained in step (III) at 60 to 100°C for 5 to 60 minutes; and step (V) of bonding together the positive electrode having the conductive polymer solid electrolyte obtained in step (IV) and a negative electrode or a negative electrode impregnated and / or surface-coated with a conductive polymer solution, and hot-pressing the resulting electrode.

Description

Technical Field

[0001] The present invention can obtain an inorganic solid electrolyte secondary battery integrally formed at extremely low cost. Furthermore, based on a conductive polymer filler in which an inorganic solid electrolyte is formulated in the pores of the positive and negative electrode electrodes having a closest-packed structure constituting the secondary battery, a heterojunction with positive and negative electrode active material particles is constructed to suppress the particle interface resistance and the interface resistance with the solid electrolyte membrane layer to the maximum extent, and to maximize the bulk conductivity performance inherent in the inorganic solid electrolyte, an ion conductive polymer matrix for improving Li ion migration is formed. Moreover, it is a manufacturing method that can obtain the characteristics of cell forming that enables the thinning and softening of the cell. The secondary battery cell manufactured by this manufacturing method can manufacture a separatorless conductive polymer inorganic solid electrolyte secondary battery with little temperature dependence and excellent safety in the case of short circuit.

Background Art

[0002] In secondary batteries that apply inorganic solid electrolytes, an inorganic solid electrolyte membrane using a polyether-based polymer as a polymer conductive polymer and further blended with ceramic whiskers has been developed as a formulation for constituting the electrolyte layer of a solid electrolyte-based secondary battery (Patent Document 1). However, in this method, the grain boundary resistance of the solid inorganic electrolyte itself is large, and interfacial resistance with the electrode occurs, resulting in insufficient conductivity performance and temperature dependence. The low-temperature characteristics are particularly poor due to usage limitations such as the optimal performance being exhibited by maintaining the secondary battery cell at 60°C or higher, and practical application is limited. Furthermore, as a conductive polymer solid electrolyte layer, a method of providing a garnet-based inorganic solid electrolyte layer and a polyether-based polymer solid electrolyte layer has also been developed (Patent Document 2). However, this method has problems such as the high softening point of the polyether-based polymer being affected by the conductivity performance and the intrinsic conductivity of garnet-based and NASICON-based inorganic solid electrolytes being significantly reduced. When using inorganic solid electrolytes such as sulfide-based ones like lithium phosphorus sulfide (LPS), physical processes such as sintering rare earth metals such as niobium (Nb) on the positive electrode active material side or heat-bonding a particle interface-coated solid electrolyte are also known as methods for improving the interfacial resistance of inorganic solid electrolyte material particles (Patent Document 3). However, these methods require equipment processes involving excessive capital investment, and there are issues in terms of cost-performance evaluation competitiveness in mass production. Also, a conductive material containing a polymer or copolymer of a molten salt monomer having a quaternary ammonium salt structure composed of a quaternary ammonium cation and a halogen atom-containing anion and a polymerizable functional group in the composite polymer conductive composition containing the graft polymer described in Patent Documents 1 to 2 above is blended with a ceramic-based solid electrolyte and used in an inorganic solid electrolyte-based lithium-ion battery (Patent Document 4). However, Patent Documents 1 to 4 do not disclose specific formulations for efficiently obtaining a high-performance inorganic solid electrolyte-based lithium-ion battery.

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2002 - 313424 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2014 - 238925 [Patent Document 3] International Publication WO2013 / 073038 [Patent Document 4] International Publication WO2018 / 043760 [Summary of the Invention] [Problems to be Solved by the Invention]

[0004] The present invention aims to manufacture a solid - electrolyte secondary battery by integrally molding or two - layer molding an electrode and an inorganic solid electrolyte layer at extremely low cost and then performing a lamination process with a counter electrode. Further, it aims to manufacture a high - performance polymer - conductive polymer solid - electrolyte secondary battery, particularly a lithium - ion battery (LIB), in which the particle - interface resistance between positive and negative electrode active - material particles and the interface resistance between a conductive polymer and an inorganic solid electrolyte layer are suppressed. In particular, by using a lithium - metal foil as the negative electrode and forming a film on the lithium - metal foil interface by heat - crosslinking or photopolymerization of a higher - capacity polymer conductive polymer as a reduction - buffering layer, a conductive - polymer solid - electrolyte secondary battery with improved reduction - resistance stability can be produced. [Means for Solving the Problems]

[0005] The above object is achieved by providing a method for manufacturing a secondary battery in which a conductive polymer solid electrolyte solution containing a conductive polymer and an inorganic solid electrolyte is applied, or the conductive polymer solid electrolyte membrane is disposed between a positive electrode and a negative electrode. The method includes the following steps: Step (I) of fabricating a positive electrode having a closest-packed structure with a pore filling rate of 70% or more by formulating an active material, a conductive material, and an ion-conductive binder; Step (II) of impregnating and filling and / or surface thin-film coating the positive electrode obtained in Step (I) with a conductive polymer solution; Step (III) of preparing a casting slurry by blending an inorganic solid electrolyte into the conductive polymer solution, applying it to the positive electrode and negative electrode obtained in Step (II), surface coating it, and integrally molding it, or by fabricating a conductive polymer solid electrolyte membrane and pressing it to form a two-layer structure to fabricate the positive electrode; Step (IV) of heating the positive electrode having the conductive polymer and the inorganic solid electrolyte obtained in Step (III) at 60 to 100 °C for 5 to 60 minutes; and Step (V) of laminating and thermally pressing the positive electrode having the conductive polymer solid electrolyte obtained in Step (IV) with a negative electrode or a negative electrode impregnated and filled and / or surface thin-film coated with a conductive polymer formulation solution. The formulation of this positive electrode can also be adapted based on the negative electrode.

[0006] Further, the object of the present invention is more preferably achieved by providing a method for manufacturing a secondary battery with a conductive polymer formulation solid electrolyte. The method includes the following steps: Step (I) of fabricating a negative electrode having a closest-packed structure with a pore filling rate of 70% or more by formulating an active material, a conductive material, and an ion-conductive binder; Step (II) of impregnating and filling and / or surface thin-film coating the negative electrode obtained in Step (I) with a conductive polymer solution; Step (III) of preparing a casting slurry by blending an inorganic solid electrolyte into the conductive polymer solution, applying it to the negative electrode obtained in Step (II), surface coating it, and integrally molding it, or by fabricating a conductive polymer solid electrolyte membrane and pressing it to form a two-layer structure to fabricate the negative electrode; Step (IV) of heating the negative electrode having the conductive polymer and the inorganic solid electrolyte obtained in Step (III) at 60 to 100 °C for 5 to 60 minutes; and Step (V) of laminating and pressing the negative electrode obtained in Step (IV) with the positive electrode.

[0007] Further, in the present invention, the object is achieved more preferably by providing a method for manufacturing a conductive polymer - formulated solid electrolyte secondary battery, which includes: step (I) of fabricating a cathode having a closest - packed structure with a pore filling rate of 70% or more by formulating an active material, a conductive material, and an ion - conductive binder; step (II) of impregnating and filling and / or surface - coating the cathode obtained in step (I) with a conductive polymer solution; step (III) of preparing a casting slurry by blending an inorganic solid electrolyte into the conductive polymer solution obtained in step (II), surface - coating the slurry, and integrally molding it, or by preparing a conductive polymer membrane and laminating it to form a two - layer molded cathode; step (IV) of heating the cathode having a conductive polymer and an inorganic solid electrolyte layer obtained in step (III) at 60 - 100°C for 5 - 60 minutes; and step (V) of laminating and thermally pressing the cathode having a conductive polymer - formulated inorganic solid electrolyte obtained in step (IV) and a lithium metal foil anode having a polyether - based polymer buffer film formed on one or both sides of the lithium metal foil.

[0008] Also, in the present invention, the object is more preferably achieved by providing a method for manufacturing a conductive polymer - formulated solid electrolyte secondary battery, in which an ionic liquid and / or a charge - transfer ion source is blended into the conductive polymer - formulated solution in step (II) and / or the conductive polymer - inorganic solid electrolyte - formulated casting slurry in step (III). Further, in the present invention, the object is more preferably achieved by providing a method for manufacturing a conductive polymer - formulated solid electrolyte secondary battery, in which impregnation and filling and / or surface - coating in step (II) is performed, and drying is carried out at 120°C or lower for 5 minutes to 1 hour. Also, in the present invention, the object is more preferably achieved by providing a method for manufacturing a conductive polymer - formulated solid electrolyte secondary battery, in which the ion - conductive binder and the conductive polymer are a polymer conductive composition obtained by graft - polymerizing or living - radical polymerizing a molten - salt monomer having a salt structure composed of an onium cation and a halogen - containing anion and having a polymerizable functional group onto a fluorine - based polymer.

[0009] Further, the object of the present invention is more preferably achieved by providing a method for manufacturing the conductive polymer formulation solid electrolyte secondary battery according to the invention, wherein the molten salt is a molten salt containing a salt structure composed of an onium cation and a halogen-containing anion, the charge transfer ion source is a lithium ion source, and a conductive polymer electrolyte having a lamellar structure is formed by the heating process in step (IV). Further, the object of the present invention is more preferably achieved by providing a method for manufacturing the conductive polymer formulation solid electrolyte secondary battery according to the invention, wherein the inorganic solid electrolyte is at least one inorganic solid electrolyte selected from garnet (GARNET)-based substances, oxide substances having a NASICON-type crystal structure, perovskite-type substances, and sulfide-based substances.

[0010] Further, the object of the present invention is more preferably achieved by providing a method for manufacturing the conductive polymer formulation solid electrolyte secondary battery according to the invention, wherein at least a part of the conductive polymer formulation inorganic solid electrolyte layer, the positive electrode, and the negative electrode contains a polyether-based polymer. In the above-described invention, the object of the present invention can be more preferably achieved by incorporating an inorganic solid electrolyte into the positive electrode material and / or the negative electrode material containing the active material, the conductive material, and the ion-conducting binder. Furthermore, the present invention is more preferably achieved by the fact that the casting slurry of the conductive polymer is a paste-like substance obtained by blending a molten salt and a charge transfer ion source with the conductive polymer powder.

Advantages of the Invention

[0011] According to the present invention, a solid electrolyte secondary battery integrally formed at extremely low cost can be obtained. Further, as is also clear from the examples described later, generation of dendrites can be prevented, and a high-performance secondary battery with suppressed grain boundary resistance between the conductive polymer layer, the positive electrode, and the negative electrode active material particles can be obtained. Furthermore, a separator-less conductive polymer solid electrolyte secondary battery can be obtained, which enables thinning of the cell, has little temperature dependence, and is excellent in safety when short-circuited. Also, when a lithium metal foil is used as the negative electrode, since a higher capacity and further thinning of the cell thickness are possible, a secondary battery having excellent high performance with an outstanding volumetric energy density can be obtained. Further, when the surface of the negative electrode is coated with a polyether-based polymer, for example, an allyl glycidyl ether polymer, there is an effect of suppressing the generation of dendrites due to stabilization of redox resistance. Also, in dendrite suppression, formation of a lithium nitrate (LiNO 3 ) film on a lithium metal foil in a primary lithium battery is known, and using this formulation is also effective. In particular, when a sulfide-based solid electrolyte is used, it is also effective to form a film on the interface of sulfide-based particles with a non-protonic substance to improve the Li transport rate at the particle interface.

Brief Description of the Drawings

[0012] Figure 1 SEM photograph (magnification 1000 times) of the surface of the closest-packed structure Figure 2 SEM photograph (magnification 1000 times) of the cross-section of the closest-packed structure Figure 3 SEM photograph (magnification 5000 times) of the bonding points of particle-to-particle bonds and the elastic structure part Figure 4 Nyquist Plot Figure 5 (a) Process (I) for fabricating the positive and negative electrodes of the closest-packed structure (b) Process (II) for impregnating and filling the positive electrode with a conductive polymer (c) Process (III) for pressure-bonding and laminating a conductive polymer inorganic solid electrolyte layer to the positive electrode and processing step (IV) for heating the positive electrode Figure 6 Process (V) for overlapping and roll-pressing the positive and negative electrodes Step of coating a lithium metal foil of a negative electrode with a polyether-based polymer (a2-1) Step of forming a film by heat press extrusion of a paste in which a powder conductive polymer, a molten salt, and a supporting salt are blended and a solid electrolyte is homogeneously dispersed (a2-2) UV curing step

Mode for Carrying Out the Invention

[0013] In the method for manufacturing a secondary battery comprising a positive electrode / negative electrode integrally formed with a conductive polymer inorganic solid electrolyte or a conductive membrane pressure-bonded thereto according to the present invention, first, a step (I) of producing a positive electrode and / or a negative electrode having a closest-packed structure with a pore filling rate of 70% or more, which is formulated with an active material, a conductive material, and an ion-conductive binder, is required. In order to achieve the object of the present invention, particularly to obtain a high-performance secondary battery with suppressed particle interface resistance, in the LiNiCoMn system in which the active material species occupies 60% or more of the nickel component, since the LiNiMn-based active material particles have a high pH (pH 10 or more) and nickel oxide is likely to be generated at the particle interface, pretreatment with a conductive polymer interface coating material {Piotrek Co., Ltd. product number CA400AM} is effective to ensure the stability of charge transfer. A pore filling rate of 70% or more is required, preferably 80% or more, and optimally 90% or more. The pore filling rate is a value (filling rate) obtained by calculating the porosity from the volume ratio of the particle density based on the surface area and cross-sectional area by a scanning microscope. Here, as a method for obtaining a closest-packed structure with a pore filling rate of 70% or more, a method using a planetary kneading type stirrer or a method using a biaxial rotation-revolution stirrer can be mentioned as preferred examples. As a method using a planetary kneading stirrer, a general-purpose specification with a revolution speed of 0 to 35 rpm and a rotation speed of 0 to 60 rpm is preferred. As a method using a biaxial rotation-revolution stirrer, a biaxial stirrer equipped with a function of individually setting the rotation speeds of revolution and rotation is used, and the stirring conditions (temperature 50°C or less, time 5 to 30 minutes, revolution speed 500 to 1000 rpm, rotation speed 1000 to 2500 rpm, degree of vacuum variable from atmospheric pressure to 0 kPa, and vacuum treatment for 3 to 5 minutes under the condition of 0 kPa are preferred. For example, biaxial stirring devices {model: Kakuhunter 350-TV, etc.} described in Japanese Patent No. 6232151 (photochemistry) and Japanese Patent No. 6388992 (the same) can be mentioned.As a method for obtaining a closest-packed structure with a pore filling rate of 70% or more, it is more preferable to use a roll that can be heated to 40°C or higher in a roll press method using a two-axis roll multi-stage press, a method of thermocompression bonding a conductive polymer formulation-filled electrode, a method of vacuum drying under conditions of a vacuum degree of -50 to -200 Pa, preferably -100 to -150 Pa, a temperature of 60 to 100°C, preferably 70 to 90°C, or further, a method of combining these methods is also mentioned as a preferable method.

[0014] Furthermore, in the present invention, a closest-packed structure may be imparted only to the positive electrode, but it is also preferable to impart a closest-packed structure to both the positive and negative electrodes. Examples of the active materials used in the positive electrode material and the negative electrode material include ordinary active materials described later, and the conductive material also includes ordinary conductive materials such as carbon nanotubes (CNT). The ion-conductive binder and the conductive polymer used in the positive and negative electrode materials can be ordinary general-purpose resins, for example, a partially cross-linked substance of a vinylidene fluoride resin, etc., but it is most optimal to form an electrode layer with a porous closest-packed structure by point-binding of the active material and the solid electrolyte particles using the above-mentioned conductive polymer. It is also a preferable embodiment to blend an inorganic solid electrolyte. When blending an inorganic solid electrolyte, the blending ratio of the inorganic solid electrolyte is preferably 5 to 50 wt.%, more preferably 10 to 30 wt.%, based on the total amount of the active material and the conductive material. Furthermore, a dispersant and other additives can also be appropriately used. The total amount of the active material and the conductive material in manufacturing the positive electrode is 95 wt.% or more in a general formulation. In a positive electrode formulation manufactured using an ion-conductive binder, a conductive binder is produced with an ion-conductive binder amount of 5 to 7 parts by weight relative to the amount of the conductive material. After testing the binding force during the production process of the coating solution, if it is determined that there is a shortage, 1 part by weight of the ion-conductive binder amount is added and dropped for production. The remaining balance of the ion-conductive binder with a reduced amount in the formulation ratio is adjusted to 100 wt.% by adding the active material, and the coating solution is made into NV (Non Volatile By passing through the optimization process (I) that manages and finishes the fluidity according to the solid content value of the organic compound, a closely packed structure electrode with a very high conductive path is obtained. On the other hand, when manufacturing the negative electrode, the surface area of the negative electrode active material is an important indicator. Calculate the optimal amount of conductive material, pre-inspect the NMP (N-methylpyrrolidone) oil supply amount, and determine the required amount of conductive material. Once the formulation ratio of this conductive material is determined, an optimal negative electrode coating solution is prepared in the same procedure as the positive electrode formulation, and then a closely packed structure negative electrode with a high conductive path is obtained.

[0015] Next, in step (II), the closely packed structure positive electrode and / or negative electrode obtained in step (I) is impregnated and filled or surface thin film coated with a conductive polymer (a charge transfer ion source is blended into the ion conductive polymer) solution. Then it is preferably dried at 120 °C or lower, preferably at 100 - 40 °C, for 5 minutes to 1 hour, preferably for 5 minutes to 40 minutes. When impregnating and filling or surface thin film coating, it is preferable to change the concentration of the conductive polymer solution in a multi-stage manner. For example, the concentration is changed from 5 - 15 wt.% solution in the previous stage to a high concentration of 20 - 50 wt.% solution in the latter stage. In that case, by performing vacuum impregnation to fill the pores of the electrode, an electrode layer with significantly suppressed particle interface resistance with complete conductive polymer filling and a smooth film formed on the surface and an electrode with a smooth film formed on the interface can be fabricated. As a method of impregnating and filling a conductive polymer solution into a positive electrode and a negative electrode, for example, a solvent solution having a conductive polymer concentration of 5 to 15 wt.%, preferably 7 to 12 wt.%, is vacuum-impregnated and filled on the surface of the positive electrode and / or the negative electrode to fill the pores and form a hetero bond to completely cover the particle interface, thereby significantly suppressing the grain boundary resistance. Next, a method of forming a smooth film on the interface by impregnating and filling a solution having a conductive polymer concentration increased from 20 to 50 wt.% in multiple stages is preferable. The multi-stage means performing multi-stage thermal press filling in two or more stages by changing the above-mentioned conductive polymer concentration. By such multi-stage thermal press filling, it is optimal to fill the pores of the electrode layer with a conductive polymer with a pore filling rate of 70% or more more completely. Further, as a method of surface coating the conductive polymer, after the impregnation and filling into the electrode pores is completed, it is a method of coating with a thickness on the order of submicrons to several microns to form a coating of a low-concentration conductive polymer. Among these methods, the former impregnation and filling method is particularly suitable for achieving the purpose of maximizing the electrode performance of the conductive polymer solid electrolyte LIB for practical use of the present invention. Here, as the solvent, acetone or acetonitrile is suitable, but depending on the type of solid electrolyte, solvents such as G-BL (butyrolactone) and tetrahydrofuran (THF) may be suitable. The ionic conductive polymer concentration is represented by (amount of conductive polymer / total solution) × 100.

[0016] Furthermore, in step (II), after impregnating and filling and / or coating with the conductive polymer solution, it is carried out under a vacuum of less than 10 kPa at 100 °C or lower, and drying is preferably carried out within 5 minutes to 1 hour at 120 °C or lower. In order to achieve the object of the present invention, particularly to achieve the effect of reducing the interfacial resistance, a multi-stage method is more preferable as in the above case. When vacuum impregnating and filling, the concentration of the conductive polymer is also the same as the above-described impregnating and filling conditions. The vacuum impregnation may be a batch type, but a continuous type is preferable. In the case of continuous operation, it is preferably processed through a buffer zone - vacuum zone - buffer zone. When impregnating and filling or vacuum impregnating and filling, it is preferable to establish the optimum conditions according to the application while verifying the impregnating and filling state (such as the bonding state between the conductive polymer and the active material, the filling state, etc.) by taking SEM cross-sectional photographs. Impregnating and filling means that the conductive polymer penetrates into the electrode layer of the positive electrode and / or negative electrode and fills the voids in the electrode layer, and also means forming a homogeneous film on the interface. In the formation of the film on this interface, a film formation method by ultraviolet curing is also effective, in which 0.5 to 8.0% by weight of an ultraviolet curing agent is blended based on the amount of the conductive polymer, and the film is formed by multi-stage continuous irradiation at a light intensity of 10 to 40 mW / cm 2 for 1 to 10 minutes.

[0017] Furthermore, in the present invention, step (III) of manufacturing the positive electrode and / or negative electrode is important, in which the surface of the positive electrode and / or negative electrode obtained in step (II) is coated with a conductive polymer inorganic solid electrolyte and integrally formed, or a conductive membrane of the conductive polymer inorganic solid electrolyte is pressure-bonded and laminated to form a two-layer structure. As a method for coating a conductive polymer inorganic solid electrolyte, an inorganic solid electrolyte is blended into a solvent solution of a conductive polymer matrix to prepare a casting slurry, and this is dried on the surface of the positive electrode and / or negative electrode to form a film with a thickness of 1 to 30 μm, preferably 5 to 20 μm, and more preferably a uniform and homogeneous film formed from a completely degassed casting solution. In this case, if the stability of the particle interface of the selected solid electrolyte is examined and the redox resistance and the particle-specific pH affect the conductive polymer matrix blend material, the particle interface of the solid electrolyte particles (for example, LiLZTaO, LiLZAlO, LiPS, LiSO, etc.) is coated with a conductive polymer coating material (such as TREKLITE CA300SE), or it is effective to perform a pretreatment of coating the electrode active material side in contact. Next, examples of the coating method include comma coating, die coating, bar coating method, ultraviolet curing method, and blade method, but the die coating method is particularly suitable. Also, a method of blending an inorganic solid electrolyte into a solvent solution of a conductive polymer to prepare a conductive membrane and press-bonding this to the surface of the positive electrode and / or negative electrode is also mentioned. It is preferable to use the conductive polymer powder after blending auxiliaries such as molten salts, further lithium supporting salts, and ionic liquids described later as a paste-like composite.

[0018] Next, the processing step (IV) of heating the positive electrode and / or negative electrode having the conductive polymer inorganic solid electrolyte layer obtained in step (III) at 60 to 100 °C for 5 to 60 minutes is important. By this step (IV), the integral molding of the conductive polymer inorganic solid electrolyte and the positive electrode and / or negative electrode that are most densely packed is completed. As a more suitable heating method at 70 to 90 °C for 5 to 30 minutes, heat treatment in a drying tank installed in a dry room capable of cloud point management is preferable. The heating is optimally performed at 65 to 85 °C for 10 to 25 minutes. By such heating, a lamellar structure is formed in the electrolyte layer, and an effect of improving the Li ion mobility that maintains an optimal conductivity due to a homogeneous conductive network structure is obtained. Furthermore, the electrolyte layer in which this lamellar structure is formed maintains stable conductivity in the range from -40 °C to +150 °C, and extremely excellent lithium ion migration is achieved based on the fact that a stable conductive network in which dripping of the blended solution does not occur is maintained. In particular, it is optimal for forming an excellent solid electrolyte that reaches 10 to the power of minus 3 as an ion conductive polymer electrolyte layer containing an oxide-based solid electrolyte having an intrinsic ion conductivity of 10 to the power of minus 4 in the range from -20 °C to 110 °C. Finally, through step (V) of laminating the positive electrode obtained in step (IV) and the negative electrode, a conductive polymer solid electrolyte secondary battery is manufactured. The positive electrode and the negative electrode are laminated via a conductive polymer inorganic solid electrolyte layer or a conductive membrane, and after undergoing steps such as roll pressing, a secondary battery composed of a positive electrode / conductive polymer inorganic solid electrolyte layer or conductive membrane / negative electrode is manufactured. Here, the lamination may be performed at room temperature, but it is preferably at 40 to 90 °C, more preferably 50 to 80 °C, in a drying and heating step.

[0019] In this way, a cell composed of a positive electrode / negative electrode integrally formed with a conductive polymer inorganic solid electrolyte layer is manufactured in a roll shape, and a wound cell secondary battery can be obtained by a winding machine. Also, a stacked type secondary battery can be obtained by a stack cell assembling machine for the roll of the cell. Integrally forming a conductive polymer inorganic solid electrolyte layer on the surface of the negative electrode and designing the cell such that the size dimensions of the positive electrode are reduced by about 1 mm in both length and width compared to the negative electrode can prevent short - circuiting between the positive and negative electrodes. Furthermore, arranging a polyimide insulating seal on the electrode terminals is also effective in preventing short - circuits. By performing such integral forming on the negative electrode side, a secondary battery can be manufactured with high efficiency. Moreover, with a conductive polymer that can also incorporate a solid electrolyte, a positive electrode and a negative electrode filled with pores, a high - performance secondary battery can be obtained in which the interfacial resistance (grain boundary resistance) between the active material particles of the electrode layer and the filled inorganic solid electrolyte particles is significantly suppressed by hetero - bonding. Current collectors are used for these positive and negative electrodes respectively. Next, in the present invention, in step (V), a conductive polymer inorganic solid electrolyte - containing positive electrode and a negative electrode of a lithium metal foil coated on one or both sides with a polyether - based polymer containing LiNO 3 are stacked, and a method for manufacturing the conductive polymer solid electrolyte secondary battery described in the above - mentioned invention is also suitable. In the present invention, as the conductive polymer used in (step I), (step II), and (step III), various conductive polymers can be mentioned, but the following polymer conductive composition is optimal.

[0020] That is, a polymer conductive composition (X 1 ) obtained by graft - polymerizing or living - radical polymerizing a molten - salt monomer having a salt structure composed of an onium cation and a halogen - containing anion and having a polymerizable functional group onto a fluorine - based polymer. As the fluorine - based polymer used for graft - polymerization or living - radical polymerization, a polyvinylidene fluoride polymer or copolymer is preferably exemplified. Moreover, as the polyvinylidene fluoride copolymer, to vinylidene fluoride Formula: -(CR 1 R 2 -CFX)- In the formula, X is a halogen atom other than fluorine, and R 1 and R 2is a hydrogen atom or a fluorine atom, and the two may be the same or different. Here, as the halogen atom, a chlorine atom is optimal, but bromine atoms and iodine atoms are also included. A copolymer having a unit represented by is a preferred example. In addition, as the fluorine-based polymer, Formula: -(CR 3 R 4 -CR 5 F) n -(CR 1 R 2 -CFX) m - In the formula, X is a halogen atom other than fluorine, R 1 , R 2 , R 3 , R 4 and R 5 are a hydrogen atom or a fluorine atom, These may be the same or different, n is 65 to 99 mol%, m is 1 to 35 mol%. A copolymer represented by is also included. In particular, Formula; -(CH 2 -CF 2 ) n -(CF 2 -CFCl) m - In the formula, n is 65 to 99 mol%, m is 1 to 35 mol%. A copolymer represented by is preferred. When the total of n and m is 100 mol%, it is preferable that n is 65 to 99 mol% and m is 1 to 35 mol%. More preferably, n is 67 to 97 mol% and m is 3 to 33 mol%. Most preferably, n is 70 to 90 mol% and m is 10 to 30 mol%. The fluorine-based polymer may be a block polymer or a random copolymer. Also, other copolymerizable monomers can be used within a range that does not inhibit the object of the present invention. The molecular weight of the fluoropolymer is preferably 30,000 to 2,000,000 in terms of weight average molecular weight, more preferably 100,000 to 1,500,000. Here, the weight average molecular weight is measured by the intrinsic viscosity method [η] as described later.

[0021] To graft polymerize the molten salt monomer to the fluoropolymer, the atom transfer radical polymerization method using a transition metal complex can be applied. The transition metal coordinated to this complex extracts a halogen atom other than fluorine (for example, a chlorine atom) and further a hydrogen atom of the copolymer to form a starting point, and the molten salt monomer graft polymerizes to the polymer. In the present invention, a method of living polymerization of the molten salt monomer to the fluoropolymer can also be applied. The molar ratio of the monomer unit constituting the polymer is adjusted to be in the range of 98 to 10 mol% and the molten salt monomer is 2 to 90 mol%, that is, the grafting rate is adjusted to be 2 to 90 mol%. When the molten salt monomer is graft polymerized to the polymer, the polymer may be in any of a solution and a solid. These graft polymers can be obtained by the method described in the prior patent WO2010 / 113971 of the applicant of the present application.

[0022] In the present invention, the salt structure of the molten salt monomer having a salt structure composed of an onium cation and a halogen atom-containing anion and containing a polymerizable functional group includes a salt structure composed of an aliphatic, alicyclic, aromatic or heterocyclic onium cation and a halogen atom-containing anion. Here, the onium cation means an ammonium cation, a phosphonium cation, a sulfonium cation, an oxonium cation, a guanidinium cation. Examples of the ammonium cation include an alkylammonium cation, a heterocyclic ammonium cation such as imidazolium, pyridinium, and piperidinium. A salt structure composed of at least one cation selected from the following ammonium cation group and at least one anion selected from the following anion group is preferable. Ammonium cation group: Pyrrolidium cation, pyridinium cation, imidazolium cation, pyrazolium cation, benzimidazolium cation, indolium cation, carbazolium cation, quinolinium cation, pyrrolidinium cation, piperidinium cation, piperazinium cation, alkylammonium cation {however, including those substituted with an alkyl group having 1 to 30 carbon atoms (for example, an alkyl group having 1 to 10 carbon atoms), a hydroxyalkyl group, or an alkoxy group}. All of them include those in which an alkyl group, a hydroxyalkyl group, or an alkoxy group having 1 to 30 carbon atoms (for example, an alkyl group having 1 to 10 carbon atoms) is bonded to N and / or the ring.

[0023] Examples of the phosphonium cation include tetraalkylphosphonium cation (alkyl group having 1 to 30 carbon atoms), trimethylethylphosphonium cation, triethylmethylphosphonium cation, tetraaminophosphonium cation, trialkylhexadecylphosphonium cation (alkyl group having 1 to 30 carbon atoms), triphenylbenzylphosphonium cation, phosphonium cation of a phosphine derivative having three alkyl groups having 1 to 30 carbon atoms, asymmetric phosphonium cations such as hexyltrimethylphosphonium cation and trimethyloctylphosphonium cation, and the like. Examples of the sulfonium cation include trialkylsulfonium cation (alkyl group), asymmetric sulfonium cations such as diethylmethylsulfonium cation, dimethylpropylsulfonium, and dimethylhexylsulfonium. Halogen atom-containing anion group: Examples of the halogen atom-containing anion group include fluorine atom-containing anions, chlorine atom-containing anions, bromine atom-containing anions, etc., and fluorine atom-containing anions are preferred for achieving the object of the present invention. Here, examples of the fluorine atom-containing anion include BF 4 - 、PF 6 - 、C n F 2n+1 CO 2 -(n is an integer from 1 to 4), C n F 2n+1 SO 3 - (n is an integer from 1 to 4), (FSO 2 ) 2 N - 、(CF 3 SO 2 ) 2 N - 、(C 2 F 5 SO 2 ) 2 N - 、(CF 3 SO 2 ) 3 N - 、CF 3 SO 2 -N-COCF 3 - 、R-SO 2 -N-SO 2 CF 3 - (R is an aliphatic group), ArSO 2 -N-SO 2 CF 3 - (Ar is an aromatic group), CF 3 COO - Anions containing halogen atoms such as etc. are exemplified. As the polymerizable functional group in the molten salt monomer, carbon-carbon unsaturated groups such as vinyl group, acrylic group, methacrylic group, acrylamide group, allyl group, etc., cyclic ethers having an epoxy group, oxetane group, etc., cyclic sulfides such as tetrahydrothiophene, and isocyanate group can be exemplified.

[0024] (A) As the onium cation having a coincident functional group, particularly as the ammonium cation species, particularly preferably, trialkylaminoethyl methacrylate ammonium cation, trialkylaminoethyl acrylate ammonium cation, trialkylaminopropyl acrylamide ammonium cation, 1-alkyl-3-vinylimidazolium cation, 4-vinyl-1-alkylpyridinium cation, 1-(4-vinylbenzyl)-3-alkylimidazolium cation, 2-(methacryloyloxy)dialkylammonium cation, 1-(vinyloxyethyl)-3-alkylimidazolium cation, 1-vinylimidazolium cation, 1-allylimidazolium cation, N-alkyl-N-allylammonium cation, 1-vinyl-3-alkylimidazolium cation, 1-glycidyl-3-alkyl-imidazolium cation, N-allyl-N-alkylpyrrolidinium cation, and quaternary diallyldialkylammonium cation, etc. can be mentioned. However, the alkyl is an alkyl group having 1 to 10 carbon atoms.

[0025] (B) As the fluorine atom-containing anion species, particularly preferably, bis{(trifluoromethane)sulfonyl}imide anion, bis(fluorosulfonyl)imide anion, 2,2,2-trifluoro-N-{(trifluoromethane)sulfonyl)}acetimide anion, bis{(pentafluoroethane)sulfonyl}imide anion, tetrafluoroborate anion, hexafluorophosphate anion, trifluoromethanesulfonylimide anion and other anions can be mentioned. Furthermore, as the molten salt monomer (the salt of the cation species and the anion species), particularly preferably, trialkylaminoethyl methacrylate ammonium (however, the alkyl is C 1 ~C 1 0 alkyl) bis(fluorosulfonyl)imide (however, the alkyl is C 1 ~C 10 alkyl), 2-(methacryloyloxy)dialkylammonium bis(fluorosulfonyl)imide (however, the alkyl is C 1 ~C10 alkyl), N-alkyl-N-allylammonium bis{(trifluoromethane)sulfonyl}imide (wherein alkyl is C 1 ~C 10 alkyl), 1-vinyl-3-alkylimidazolium bis{(trifluoromethane)sulfonyl}imide (wherein alkyl is C 1 ~C 10 alkyl), 1-vinyl-3-alkylimidazolium tetrafluoroborate (wherein alkyl is C 1 ~C 10 alkyl), 4-vinyl-1-alkylpyridinium bis{(trifluoromethane)sulfonyl}imide (wherein alkyl is C 1 ~C 10 alkyl), 4-vinyl-1-alkylpyridinium tetrafluoroborate (wherein alkyl is C 1 ~C 10 alkyl), 1-(4-vinylbenzyl)-3-alkylimidazolium bis{(trifluoromethane)sulfonyl}imide (wherein alkyl is C 1 ~C 10 alkyl), 1-(4-vinylbenzyl)-3-alkylimidazolium tetrafluoroborate (wherein alkyl is C 1 ~C 10 alkyl), 1-glycidyl-3-alkyl-imidazolium bis{(trifluoromethane)sulfonyl}imide (wherein alkyl is C 1 ~C 10 alkyl), trialkylaminoethyl methacrylate ammonium trifluoromethanesulfonyl imide (wherein alkyl is C 1 ~C 10 alkyl), 1-glycidyl-3-alkyl-imidazolium tetrafluoroborate (wherein alkyl is C 1 ~C 10 alkyl), N-vinylcarbazolium tetrafluoroborate (wherein alkyl is C 1 ~C 10Examples thereof include alkyl). These molten salt monomers can be used alone or in combination of two or more. These molten salt monomers can be obtained by the method described in the applicant's prior patent WO2010 / 113971 mentioned above. The grafting rate of the molten salt monomer onto the fluoropolymer is preferably 2 to 90 mol%, more preferably 10 to 85 mol%, and most preferably 20 to 80 mol%. By satisfying the grafting rate within this range, the object of the present invention can be more preferably achieved. In the region where the grafting rate is relatively low, for example, 2 to 40 mol%, preferably 5 to 35 mol%, and more preferably 5 to 30 mol%, the oxidation resistance property is improved and the flexibility of the sponge-like property can be maintained, and the effects of improving the bonding adhesion, elasticity, and adhesiveness to the support can be expected. In the region where the grafting rate is relatively high, for example, 40 to 90 mol%, particularly 45 to 85 mol%, and more preferably 50 to 80 mol%, the viscoelasticity increases, so the adhesion strength is improved, and further, the effects of adhesiveness, impact resistance, dispersion smoothness of particulate materials such as pigments, pH stability, temperature stability, and further improvement of the conductive performance can be expected. When using this as a conductive polymer, those in the range of 2 to 90 mol% of the grafting rate can be used, but when using it as an ion conductive binder, those in the range of a low grafting rate of 5 to 50 mol% are more preferably used.

[0026] For the graft polymerization of the molten salt monomer, the molten salt alone can be used, or other monomers copolymerizable with the molten salt monomer can also be used. Here, the polymer electrolyte composition (X 1 ) includes a monomer composition containing SEI (Solid Electrolyte Interphase) film-forming materials such as vinylene carbonates, vinylene acetate, 2-cyanofuran, 2-thiophenecarbonitrile, acrylonitrile, or solvents. In the present invention, the polymer conductive composition (X 1 ), which is a conductive polymer or an ion conductive binder, is used as the ionic liquid (X 2) is incorporated to form a conductive polymer matrix, and using this is suitable because it can form a conductive polymer with a lamellar structure and further improve conductivity and conductive durability. Here, as the ionic liquid (X 2 ), a molten salt composed of an onium cation and a halogen-containing anion is suitable, and examples include molten salts composed of the ammonium cation group and the halogen-containing anion group described above. For example, cyclic conjugated ionic liquids in which the cation is shared by two nitrogens, acyclic aliphatic ionic liquids containing alkylammonium or phosphonium, cyclic aliphatic ionic liquids containing quaternary ammonium, various ionic liquids of pyrrolidinium cations, etc. can be mentioned. More specifically, 1-ethyl-3-methylimidazolium bis(fluoromethanesulfonyl)imide (EMI·FSI), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI·TFSI), 1-butyl-3-methylimidazolium bis(fluoromethanesulfonyl)imide (BMI·FSI), 1-methyl-1-butylpyrrolidinium bis(fluoromethanesulfonyl)imide (MBPy·FSI), etc. are mentioned as suitable ones. Also, as the ionic liquid (X 2 ), a molten salt monomer (ionic liquid) having a salt structure composed of an onium cation and a halogen-containing anion and having a polymerizable functional group can also be mentioned. Examples of this molten salt monomer include the molten salt monomers used for the graft polymerization described above. The blending ratio of the polymer conductive composition (X 1 ) is 5 to 90 wt.%, preferably 50 to 80 wt.%, based on the total amount of the polymer conductive composition (X 1 ) and the ionic liquid (X 2 ). Further, in the conductive polymer of the present invention, by blending a charge transfer ion source (supporting salt), the conductivity and conductive durability are improved by applying the chelate effect. Here, as the charge transfer ion source, typically, a lithium salt is used, and preferably a lithium salt composed of the following lithium cation and a fluorine atom-containing anion is used.

[0027] As the charge transfer ion source, LiBF 4 , LiTFSI, LiPF 6 , C n F 2n+1 CO 2 Li (where n is an integer from 1 to 4), C n F 2n+1 SO 3 Li (where n is an integer from 1 to 4), (FSO 2 ) 2 NLi(LiFSI), (CF 3 SO 2 ) 2 NLi(LiTFSI), LiFTSI(C 2 F 5 SO 2 ) 2 NLi, (FSO 2 ) 2 CLi, (CF 3 SO 2 ) 3 CLi, (CF 3 SO 2 -N-COCF 3 )Li, (R-SO 2 -N-SO 2 CF 3 )Li (R is an aliphatic group such as an alkyl group or an aromatic group), and (CN-N) 2 C n F 2n+1 Li (where n is an integer from 1 to 4) and the like can be mentioned. Further, as those other than the lithium salt, charge transfer ion sources such as indium tin oxide (ITO) and carbonate can also be mentioned. The compounding amount of the above charge transfer ion source is 0.5 to 60 moles, preferably 0.7 to 50 moles, based on the polymer electrolyte composition (X 1 ). Various solvents are used in the polymer conductive composition. Examples of the solvent include dimethyl sulfoxide (DMSO), N-methylpyrrolidone, dimethylacetamide, acetone, acetonitrile, THF, and mixed solvents thereof. The above-mentioned conductive polymer is obtained by the method described in PCT / JP2018 / 018439 (Japanese Patent Application No. 2018-22496), pages 3, line 5 to page 9, line 24.

[0028] Furthermore, in the present invention, when the negative electrode is fabricated with a water-soluble binder, a water-soluble ionic conductive binder can be fabricated and used by copolymerizing a water-soluble polymer material such as polyvinyl alcohol or polyvinyl butyrate with an ionic liquid having a double bond such as 2-(methacryloyloxy)ethyltrimethylammonium-anion (MOETMA-Anion), diallyldimethylammonium-anion (DAA-Anion), and 1-ethyl-3-vinylimidazolium-anion (EVI-Anion). Here, as the anion, BF 4 - etc. are preferably used. In addition, the above-mentioned copolymerized water-soluble ionic conductive binder can also be used as an alternative material for water-soluble binder formulations such as styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) which are general-purpose formulations. In this case, it is also preferable to blend a water-soluble auxiliary dispersant such as polyvinylpyrrolidone (PVP). It is also possible to blend CMC for the purpose of further improving film properties. It is also possible to form a close-packed structure negative electrode using these water-soluble ionic conductive binders.

[0029] Next, in the present invention, the inorganic solid electrolyte to be used will be described. As the inorganic solid electrolyte, garnet-based substances, substances having a NASICON type crystal structure, perovskite-type substances, sulfide-based substances, etc. can be used. Among these, garnet-based substances are preferable for achieving the object of the present invention, so first, garnet-based substances will be described. Examples of suitable garnet-based substances include oxide-based solid electrolytes such as LLZO-based and LLT-based. In addition, examples of substances having a NASICON type crystal structure of the inorganic solid electrolyte include the following LATP-based and LAGP-based solid electrolytes. In particular, Li (1+X) Al X Ti (2-X) (PO 4 ) 3 (X is 0.1 to 1.5, preferably 0.1 to 0.8) represented by the oxide-based substance {for example, Li 1.4Al 0.4 Ti 1.6 (PO 4 ) 3 etc.} are suitable. Furthermore, Li (1+4X) Zr (2-X) (PO 4 ) 3 (X is 0.1 to 1.5, preferably 0.1 to 0.8) and substances represented thereby (a part of Zr may be substituted with at least one element selected from Al, Ca, Ba, Sr, Sc, Y, and In) etc. can also be mentioned. By using the substance having this NASICON-type crystal structure in combination with the above polymer conductive composition, the particle interface resistance can be suppressed.

[0030] As other LATP systems, Li 3 PO 4、 Li 4 SiPO 4、 Li 4 SiPO 4 -Li 3 PO 4、 Li 3 BO 4 can be mentioned. Also, as perovskite-type substances of inorganic solid electrolytes, oxide-based substances represented by La X Li Y TiO Z etc. can be mentioned. The particles of these oxide-based substances can more effectively reduce the particle interface resistance value when they are in the nano size (nm) rather than in the μm particle size, and are suitable. Furthermore, as sulfide-based substances (LPS) of inorganic solid electrolytes, 75%Li 2 S·25%P 2 S 5 、Li 3.25 P 0.95 S 4 、Li 3.2 P 0.96 S 4 、Li 4 P 2 S 6 、Li 7 P 3 S 11 、Li 6 PS 5 Cl、Li 3 PS 4Examples of the sulfur-containing substances include those represented by etc. By using this sulfur-containing substance in combination with the above-described polymer conductive composition, it is possible to suppress the particle interface resistance and the electrode interface resistance, and to reduce the generation of harmful gases in the case of a combustion accident due to the occurrence of a short circuit or the like. In the case of the sulfur-containing substance, since non-polar toluene, hexane, and tetrahydrofuran are used as solvents that are soluble or dispersible, by forming a film on the sulfur particle interface with an ion conductive coating material {such as Piotech Co., Ltd. product number CM2100}, the obtained casting slurry of the sulfur particles coated with the ion conductive polymer film is applied to the electrode and integrally molded, or the conductive membrane obtained from the casting slurry is two-layer molded onto the electrode, and a molded body in which the electrode is bonded can be produced. The above-described inorganic solid electrolyte is described on page 9, line 25 to page 10, line 26 of PCT / JP2018 / 018439 (Japanese Patent Application No. 2018-22496). In addition, in the conductive polymer solution in the step (II), and further in the casting slurry in which the inorganic solid electrolyte is formulated in the conductive polymer solution in the step (III), the above-described ionic liquid (X 2 ) and / or a charge transfer ion source are blended, whereby the object of the present invention can be more preferably achieved.

[0031] Next, an embodiment in which a polyether-based polymer is used in a part of the positive electrode / conductive polymer inorganic solid electrolyte / negative electrode will be described. In the present invention, including a polyether-based polymer in a part of the positive electrode / conductive polymer inorganic solid electrolyte layer / negative electrode means that a polyether-based polyol monomer is applied to the surface (one side or both sides) of the lithium metal foil negative electrode, and an ultraviolet curing agent of 0.5 to 8.0 wt.% is used with respect to the amount of the conductive polymer, and the film is formed by irradiation with a light intensity of 10 to 40 mW / cm 2 for 1 to 5 minutes or the film is formed by heat curing. The polyether-based polymer film on one side or both sides of the lithium metal foil means a buffer film (a film layer that suppresses the generation of dendrites). The polyether monomer is preferably a partially crosslinked polyether polyol monomer, and an optimal one is a crosslinked polymer of a polyether polymer obtained by ring-opening polymerization of allyl glycidyl ether and ethylene oxide and a polyether polyol poly(meth)acrylate obtained by acylating the ends of a trifunctional polyether polyol obtained by adding ethylene oxide to glycerin with (meth)acrylic acid. It is preferable to use a polymer matrix obtained by blending a molten salt and a lithium salt with a glycidyl ether / alkylene oxide copolymer having a radically polymerizable allyl group in the side chain and heating it, or by photopolymerization. Furthermore, it is preferable to form a film at the interface of a lithium metal foil with a polymer material copolymerized with an ionic liquid having a double bond, such as MOETMA-Anion), DAA-Anion, EVI-Anion, etc., in a polyether polymer obtained by ring-opening polymerization of allyl glycidyl ether and ethylene oxide. In this formulation, it is also effective to blend 2 to 10 wt.% of lithium nitrate with respect to the polymer material for the purpose of suppressing dendrite generation.

[0032] The polyether polyol, which is the nonpolar polymer described above, is described on pages 10, line 34 to page 13, line 1 of PCT / JP2018 / 018439 (Japanese Patent Application No. 2018-22496). This polyol material can be used as a raw material for copolymerization with an ionic liquid. By using these polyether polymers, the oxidation-reduction resistance characteristics are improved, and particularly, when a lithium metal foil is used for the negative electrode, a high level of reduction resistance characteristics may be imparted. Furthermore, a polymer conductive composition in which the grafting rate of the molten salt monomer to the fluorine-based polymer is in the range of 5 to 45 mol is used as an ion conductive binder for manufacturing a negative electrode and a positive electrode, and an inorganic solid electrolyte corresponding to 5 to 30 wt.% of the active material can also be used to partially replace the active material. In particular, since the compatibility between the positive and negative electrodes and the solid electrolyte produced in this formulation and the conductive polymer solid electrolyte layer produced with the polymer conductive composition (containing a supporting salt) is improved, the internal resistance of the lithium secondary battery cell is reduced and Li +It becomes possible to further improve the charge transfer coefficient of ions.

[0033] In the present invention, the blending ratio of the inorganic solid electrolyte and the polymer conductive composition is such that the inorganic solid electrolyte is contained in an amount of 1 to 99 wt.%, preferably 40 to 98 wt.%, and more preferably 60 to 90 wt.%, based on the total amount of the polymer conductive composition (containing a supporting salt) and the inorganic solid electrolyte. As the active material of the positive electrode used in the present invention, a lithium-based metal compound is preferably used. Examples of the lithium-based metal compound include LiCoO 2、 LiNiO 2、 LiFeO 2、 LiMnO 3、 LiMn 2 O 4、 Li 2 Mn 2 O 4、 LiNi 0.5 Mn 1.5 O 4、 LiCo 1 3 Ni 13 Mn 13 O 2、 LiFePO 4、 LiCoPO 4、 LiNiPO 4、 LiMnPO 4、 LiNi 8 Co 1 Mn 1 are exemplified.

[0034] Furthermore, in addition to the above-described positive electrode active material, a conductive material is used for the positive electrode. Examples of the conductive material include natural graphite, artificial graphite, hard carbon, MCMB (mesophase microspheres), nanoparticle carbon, carbon nanofiber (VGCF), and carbon nanotube (CNT). Also, a part of the conductive material can be replaced with a conductive polymer solid electrolyte, and a polymer electrolyte in a region with a low grafting rate can be used as an ion-conducting binder. As the active material of the negative electrode used in the present invention, carbon materials such as natural graphite, artificial graphite, hard carbon, and MCMB (mesophase microspheres), and furthermore, Li 4 Ti 5 O 12Examples include LTO (lithium titanate), SiO / carbon (e.g., Graphite) materials of silicon-based materials, lithium metal foil, etc. In addition to these negative electrode active materials, a conductive material is used for the negative electrode. As the conductive material, natural graphite, artificial graphite, hard carbon, MCMB (mesophase microspheres), carbon nanoparticles, carbon nanofibers (VGCF), carbon nanotubes (CNT), etc. are used. However, when using lithium metal foil, these conductive materials are not necessary. The active material and the conductive material used for the negative electrode may be the same substance as the conductive material used for the positive electrode, but it is preferably a different substance. The above-described positive electrode and negative electrode are described on pages 13, line 23 to page 14, line 31 of PCT / JP2018 / 018439 (Japanese Patent Application No. 2018-22496). In the present invention, by using an inorganic solid electrolyte and a polymer conductive composition (conductive polymer), a LIB cell can be constructed without using a separator, but a separator may also be used.

Examples

[0035] The present invention will be further described by the following examples. Example 1 Process - I Closest Packing Structure Positive Electrode Fabrication Process (upper figure in Fig. 5) LiNi 8 Co 1 Mn 1 (NCM811) active material, conductive material (acetylene black Super C65), ionic conduction binder [Piotrek Co., Ltd. product name CBC5410FP; polymer conductive composition {vinylidene fluoride copolymer (ARKEMA's "Kynar": -(CH 2 -CF 2 )m-(CF 2 -CFCl)n (m = 96 mol%, n = 4 mol%) grafted with 20 mol% of a molten salt monomer (ionic liquid) {2(methacryloyloxy)ethyltrimethylammonium bisfluorosulfonylimide (MOETMA-FSI)} (X 1 ) formulated with a compounding aid] was used to set the positive electrode formulation. 1.6 wt% of the ion conductive binder powder in terms of solid content with respect to 2.5 wt% of the conductive material (based on 100 wt% of the total of the active material + binder + conductive material) was placed in a container and homogeneously mixed using a planetary mixer for 10 minutes to prepare a conductive binder powder. Then, a predetermined amount of N-methylpyrrolidone (NMP) was added to sufficiently immerse the conductive material, and then homogeneously stirred to prepare a conductive binder slurry. Thereafter, 8 Co 1 Mn 1 the active material was added and homogeneously kneaded and stirred using a biaxial planetary mixer for 15 minutes to prepare a coating solution. Through the particle size distribution test, dropping slide test, and adhesion test of the coating solution, while performing fine adjustment, a positive electrode with an optimal closest packing structure (pore filling rate of 70% or more) was fabricated. Thereafter, the interface and cross-section of the fabricated electrode were observed by SEM to confirm that it had the closest packing structure. Refer to the SEM photographs of the surface, cross-section of the closest packing structure, and the point bonding structure between particles (see Fig. -1, Fig. -2, Fig. -3) Furthermore, an electrochemical property test was carried out, and compared with the same-formulated positive electrode fabricated by general-purpose PVdF (polyvinylidene fluoride), there was a significant improvement in IR drop, an improvement in low-temperature characteristics, and a 20% reduction in the binder amount from 2.0 wt% formulation (in the total coating solution formulation) to 0.4 wt%, which led to an increase in the active material and an ion conductive binder formulation electrode with improved volume energy density.

[0036] Example 2 Other process - 1 Closest packing structure positive electrode fabrication process (the upper figure in Fig. 5) Under the same conditions as in Example 1 above, LiNi 8 Co 1 Mn 1 (NCM811) active material, conductive material (acetylene black Super C65) conductive material, and ion conductive binder {Piotrek Co., Ltd. product number CBC5430FP; a product obtained by blending a dispersant with CBC5410FP in Example 1} were kneaded in the same formulation using a biaxial planetary mixer {Shashin Kagaku Co., Ltd. product number Kakuhanta SK350T} under the conditions of 1000 rpm revolution and 1500 rpm rotation to fabricate the same electrode. The closest packing structure of the obtained positive electrode had a pore filling rate of 70% or more. As a result, compared with a planetary stirrer, the conductive binder was produced in about half the time to produce a homogeneous fabric, and the amount of the ion conductive binder used was also reduced by 20%, leading to an improvement in the volume energy density due to a further increase in the active material. On the other hand, the production of the closest-packed structure negative electrode (the lower figure in Fig. 5) is based on a formulation that depends on the proportional amount of the conductive material according to the surface area of the natural spherical graphite. However, the amount of the ion conductive binder {Piotrek Co., Ltd. product number CBA9230FP} used can be adjusted according to the surface area conditions of the negative electrode active material to produce an optimal fluid coating solution. An equivalent closest-packed structure negative electrode (pore filling rate of 70% or more) was produced by the same manufacturing method with a 70% formulation of the conductive material.

[0037] Example 3 Process - IIa Conductive polymer filling into the positive electrode and formation of a conductive polymer matrix film (Fig. 5b) A molten salt (ionic liquid type) and a Li salt {lithium bis(fluorosulfonyl)imide salt (LiFSI)} were blended with the conductive polymer type used in Example 1 to produce a conductive polymer filler (ICPm). This conductive polymer filler was impregnated and filled into the closest-packed structure positive electrode produced in Process - I of Example 1 with a solution having a first slurry concentration of 10 wt.%, and then multi-stage impregnation and filling were performed while increasing the slurry concentration at any time (filling rate of 80% or more). As a result, it was confirmed by observing the surface and cross-section of the conductive polymer filled electrode that the filling was completed at 90% or more. Then, a conductive polymer matrix solution {Pioletek Co., Ltd. product number TP-CE2100} was coated on each electrode interface to form an interface film. Due to this film formation layer, the interfacial resistance was significantly reduced, and a result with an interfacial resistance of 100 Ω or less was obtained in the Nyquist plot (complex impedance index). (See Fig. 4)

[0038] Example 4 Process - IIa Conductive polymer filling into the negative electrode and formation of a conductive polymer matrix film (Fig. 5b) A conductive polymer filler is prepared by blending the conductive polymer species, molten salt (ionic liquid species), and Li salt (LiFSI) used in Example 2. This conductive polymer filler is filled into the closest-packed structure negative electrode fabricated in Step (II) of Example 2 with a solution having a first slurry concentration of 10 wt.%, and the slurry concentration is increased as needed to perform multi-stage impregnation filling. To confirm this result, the surface and cross-section of the conductive polymer-filled electrode were observed, and it was confirmed in the same manner as in Example 3 that the filling (filling rate of 70% or more) was completed. Thereafter, a conductive polymer matrix solution {Piotrek Co., Ltd. product number TP-CE2100} was coated on each electrode interface to form an interfacial film.

[0039] Example 5 Step - IIb Formation of a reduction-resistant buffer film on the lithium metal foil of the negative electrode A 30-μm-thick lithium metal foil was used for the negative electrode, and a conductive monomer having a polyether-based polyol composition was thermally cured at 80 °C for 1 hour as a reduction-resistant buffer film on the interface to form a 10-μm film. Due to the formation of this buffer film, stable electron transfer of the Li metal foil - copper foil negative electrode was achieved. (Figure 7)

[0040] Example 6 Step - III Fabrication of a conductive polymer matrix slurry and a casting slurry blended with a solid electrolyte (Figure 5c) LAGP was selected from GARNET-type solid electrolytes as the solid electrolyte. An ionic liquid (molten salt) {1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide} (EMI-FSL) and Li salt (LiFSI) were blended with the conductive polymer to prepare a conductive polymer matrix solution, and the selected solid electrolyte was blended to prepare a casting slurry. This slurry was applied to a Teflon plate, and a conductive membrane was prototyped at 120 °C for 1 hour to confirm that the conductivity was 1.6x10 -4 S / cm, and it was verified that the casting slurry was completed. Furthermore, as a result of the suspension heat resistance test from -40 °C to 150 °C due to the formation of the lamellar structure of the molten salt, it was confirmed that no dripping occurred and it was incorporated into the lamellar structure.

[0041] Example 7 Step-IV The conductive polymer matrix solid electrolyte casting slurry produced in Step-III was coated on the surface of the negative electrode and cured at 80 °C for 30 minutes to fabricate a half-cell integrally formed with the negative electrode having a smooth interface.

[0042] Example 8 Step-V A densest-packed positive electrode filled with the conductive polymer produced in Step-IIa was overlaid on the integrally formed half-cell of the conductive polymer matrix-solid electrolyte (SE) and the negative electrode produced in Step-IV, and hot roll pressing was performed to fabricate an internal cell of the solid electrolyte secondary battery (Fig. 6). Example 9

[0043] Step-V A conductive membrane was fabricated by blending a LiLZTaO solid electrolyte whose particle interface was coated with a conductive polymer coating material {Piotrek Co., Ltd. product number CE2100SE} in a conductive polymer matrix solution, and the conductive membrane was sandwiched between the positive and negative electrodes produced in Steps-IIa and IIb and subjected to pressure hot pressing to fabricate a conductive polymer matrix solid electrolyte lithium secondary battery.

[0044] Example 10 Step V A molten salt {ionic liquid; a blend of N-methyl-N-propylpiperidinium bis(fluorosulfonyl)imide (MPPY-FSI) and 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI)} in which a Li salt (LiFSI) was blended in a conductive polymer {Piotrek Co., Ltd. product number G75CM311} powder was used to produce a homogeneous paste-like substance with a completely defoaming type biaxial self-revolving stirrer {(Shashin Kagaku Co., Ltd. product number SK-350TV)}, and a film was formed on the negative electrode by a heat press extrusion method. (Fig. 7a2-1)

[0045] Example 11 Instead of the negative electrode produced in Step-IIb, a 30-μm lithium metal foil was laminated on a current collector copper foil, a photopolymerization initiator (Irgacure369) was blended in a polyether-based polyol monomer solution in an amount of 3% and applied to the lithium metal foil interface, and 30 mW / cm 2An LED lamp light source was irradiated for 2 minutes under the condition of 365 nm to form a 10-μm-thick film. It was confirmed that not only the reduction resistance was improved by this film formation, but also the generation of dendrites could be suppressed. (Fig. 7a2-2)

[0046] Example 12 Oxide-based GARNET, for example, LLZO-Al (solid electrolyte (product with a thickness of 300 nm manufactured by Ampcera)) was dissolved in a 10 wt.% acetonitrile solution, and an ionic conductive polymer system {product number CE2100 manufactured by Piotech Co., Ltd.} containing a Li salt (for example, LiFSI) was homogeneously mixed to prepare a casting slurry solution with low viscosity (20 cps or less). A close-packed structure electrode prepared in advance, for example, a high-Ni-containing active material LiNi 8.5 Co 1.0 Mn 0.5 (manufactured by Cosmo), a conductive material (Super C65), and an ion-conductive binder {product number CE2100 manufactured by Piotech Co., Ltd.} were formulated to form a close-packed structure (packing rate of 70% or more) electrode (NCM85105 positive electrode). A mixed slurry (viscosity, 20 cps or less) of a 10 wt.% acetonitrile solution of LLZO-Al and an ionic conductive polymer system {Piotech Co., Ltd. product number CE2100} was heated to 40 °C and impregnated into the pores of the close-packed structure electrode {Process (II)}. Next, the above solution (casting slurry containing a conductive polymer and a solid electrolyte) was multi-stage impregnated (multi-stage impregnation by changing the concentration of the slurry) using a biaxial roll press (under the condition of heating to 50 °C) and filled {Process (III)}. Then, the NCM positive electrode after impregnation and filling was heat-treated at 80 °C for 20 minutes, so that the solid electrolyte contained in the electrode and the ionic conductive polymer system was bonded as a heterojunction. As a result, a conductive network structure with a complex impedance resistance value of 100 Ω or less was formed in the processed electrode, and a performance with a Li ion migration coefficient (transport rate) of 0.5 or more was exhibited. As a result, an electrode with controlled interfacial resistance in the formation of an optimal conductive network was fabricated. This formulation is also applicable to positive electrodes such as LCO, NCA (NiCoAl), LMO, LFP, and natural spherical graphite, artificial graphite, LTO, and silicon-carbon negative electrodes. In addition, as solid electrolyte types, it is also applicable to NASICON-based and GARNET-based ones. Various oxide-based solid electrolytes were fabricated in an ion-conductive polymer system on the upper layer of these optimally conductive network structure electrodes, and the casting slurry could be integrally formed on the electrode layer by comma coating method, die coating method, etc.

[0047] Example 13 Separately, an ion conductive binder {Piotrek Co., Ltd. product number CE2100}, LiNi 6 Co 2 Mn 2 active material and conductive material (Super C65)} were formulated, and a low-viscosity solution (20 cps or less) of a polyether allyl glycidyl ether liquid containing an Li salt was heated to 40 °C or higher and mixed with a closely packed structure electrode (positive electrode). A THF solution of an ion conductive polymer system {Piotrek Co., Ltd. product number CE2100} was mixed to obtain a homogeneous and completely degassed solution, which was then multi-stage pressed and impregnated by a biaxial roll press (at 50 °C or higher) {Process (II)}. Next, an LPS and 75% Li 3 PS 4 (LPS) and 75% Li 2 S·25% P 2 S 5 A THF casting slurry was prepared at a ratio of 70:30 of a sulfide-based solid electrolyte - ion conductive polymer system (Piotrek Co., Ltd. product number G75CM311) and impregnated and filled to a thickness of 5 μm by the comma coating method to form a conductive electrolyte layer {Process (III)}. Then, a negative electrode was bonded to the positive electrode obtained by multi-stage roll press impregnation filling into the pores of the closely packed structure electrode, and dried at 80 °C for 20 minutes under a vacuum condition of -0.1 mPa to fabricate an electrode - solid electrolyte {Process (IV)}. As a result, a half cell with a performance of complex impedance of 100 Ω or less with the interfacial resistance between the electrode and the solid electrolyte layer controlled was completed. This manufacturing method is for sulfide-based LiP 2 S5 It was also applied to LISICON type solid electrolytes and achieved a complex impedance of 80 Ω or less. Furthermore, after fabricating the optimum filling structure electrodes for various positive electrodes such as LiFePO, high-nickel-based NMC, and LiMO, and natural spherical graphite, LTO, Si-C active materials, etc., and various negative electrodes, and creating and evaluating the electrode-solid electrolyte in the same step (IV) as above, equivalent performance was obtained. Furthermore, by changing the solid electrolyte: ion conductive polymer matrix system to a ratio of 85:25 and fabricating it by the above manufacturing method, a cell performance with higher conductivity was obtained.

Industrial Applicability

[0048] According to the present invention, a secondary battery in which a solid electrolyte processed negative electrode integrally formed at extremely low cost and an interface-processed positive electrode are stacked can be obtained. Even without a separator, the generation of dendrites can be prevented, and a high-performance practical secondary battery with suppressed particle interface resistance (grain boundary resistance) between the conductive polymer layer, the positive electrode, and the negative electrode active material particles can be obtained. Therefore, it is highly expected as a manufacturing method for solid electrolyte secondary batteries in the future.

Explanation of Reference Numerals

[0049] 1 Positive electrode kneading 2 Coating 3 Drying 4 Positive electrode roll winding 5 Positive electrode roll winding 6 Positive electrode sheet 7 ICPm feeder 8 Support roll 9 Two-stage feeder 10 Drying (with vacuum possible) 11 Filled positive electrode roll winding 12 Negative electrode kneading 13 Coating 14 Drying 15 Negative electrode roll winding 21 Positive electrode roll winding 22 Positive electrode sheet 23 ICPm-SE feeder 24 Support roll 25 Heating process 26 Heat press roll 27 Integrally formed positive electrode roll winding 31 Filled negative electrode roll winding 32 Integrally formed positive electrode roll winding 33 Filled negative electrode roll 34 Integrally formed positive electrode sheet 35 Support roll 36 Press roll or heat press roll 37 One-piece formed positive electrode - filled negative electrode cell roll 38 Wound cell 39 Stacked cell 41 Lithium metal foil roll 42 Current collector copper foil roll 43 Lithium metal foil roll 44 Support roll 45 Support roll 46 Support roll 47 Press roll 48 Press roll 49 Polyether-based polymer coating 50 Die coat 51 Support roll 52 Heat-curing drying chamber 53 Support roll 54 Press roll 55 Support roll 56 Pinhole detector 57 Support roll 58 Press roll 59 Lithium metal foil - current collector copper foil - lithium metal foil roll 61 Press roll 62 Paste extruder 63 Heat roll press 71 UV curing irradiator 72 UV curing box (process)

Claims

1. In a method for manufacturing a conductive polymer solid electrolyte secondary battery in which a conductive polymer solid electrolyte layer obtained by coating a solid electrolyte solution composed of a conductive polymer and an inorganic solid electrolyte is disposed between a positive electrode and a negative electrode, a step (I) of fabricating an electrode of a positive electrode and / or a negative electrode having a closest-packed structure with a pore filling rate of 70% or more, which is formulated with an active material, a conductive material, and an ion-conductive binder, a step (II) of impregnating and filling or surface thin-film coating any of the electrodes obtained in step (I) with a conductive polymer solution, a step (IIIa) of fabricating an electrode in which a conductive polymer solid electrolyte layer is integrally formed by surface coating the positive electrode and / or the negative electrode with a solution in which an inorganic solid electrolyte is blended in the conductive polymer solution obtained in step (II), or a step (IIIb) of fabricating an electrode made by pressure-bonding a conductive polymer solid electrolyte layer (conductive polymer solid electrolyte membrane) obtained from a solution in which an inorganic solid electrolyte is blended in the above-described conductive polymer to the electrode to form a two-layer structure, a processing step (IV) of heating the electrode obtained in step (III) (steps (IIIa) and (IIIb)) at 60 to 100°C for 5 to 60 minutes, and a step (V) of bonding and thermally pressing the electrode obtained in step (IV) to another electrode to manufacture a conductive polymer solid electrolyte secondary battery, wherein the conductive polymer and the ion-conductive binder are a polymer conductive composition obtained by graft-polymerizing a molten salt monomer having a salt structure composed of an onium cation and a halogen-containing anion and having a polymerizable functional group to a fluorine-based polymer.

2. The electrode fabricated in steps (I), (II), and (III) according to Claim 1 is a positive electrode, and the negative electrode in the same steps is a lithium metal foil copper foil current collector negative electrode having a polyether-based polymer buffer film formed on one or both sides of a lithium metal foil. A method for manufacturing a conductive polymer solid electrolyte secondary battery according to Claim 1.

3. In Claim 1, an ionic liquid and / or a charge transfer ion source is blended in the conductive polymer solution in step (II) and / or the solution in which an inorganic solid electrolyte is blended in the conductive polymer solution in step (III). A method for manufacturing a conductive polymer solid electrolyte secondary battery according to Claim 1.

4. The method for manufacturing a conductive polymer solid electrolyte secondary battery according to claim 1, wherein the inorganic solid electrolyte constituting the conductive polymer solid electrolyte layer contains at least one inorganic solid electrolyte selected from garnet (GARNET)-based substances, oxide substances having a NASICON (NASICON) type crystal structure, perovskite-type substances, and sulfide-based substances.

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