TWI794473B - Method for manufacturing battery member for secondary battery - Google Patents

Abstract

One aspect of the present invention provides a method for manufacturing a battery member for a secondary battery, which includes the following steps: forming an electrode mixture intermediate layer containing an electrode active material on one side of the current collector; and, forming an electrode mixture intermediate layer on the electrode mixture A step of coating a slurry containing oxide particles, a polymer, an ionic liquid, and an electrolyte salt on the side of the intermediate layer opposite to the collector; and, the total amount of the content of the ionic liquid and the electrolyte salt is relative to the oxidation The content of substance particles, in terms of volume ratio, is greater than 4/1 and less than 12/1.

Description

Method for manufacturing battery member for secondary battery

The present invention relates to a method for manufacturing a battery component for a secondary battery.

In recent years, due to the popularization of portable electronic devices, electric vehicles, and the like, high-performance secondary batteries are required. Among them, lithium secondary batteries have attracted attention as power sources such as batteries for electric vehicles and batteries for power storage because of their high energy density. Specifically, lithium secondary batteries as batteries for electric vehicles have been adopted in zero-emission electric vehicles without engines, hybrid electric vehicles equipped with both engines and secondary batteries, and plug-in batteries directly charged by the power system. Electric vehicles such as electric hybrid electric vehicles. Also, lithium secondary batteries, which are batteries for power storage, have been used in stationary power storage systems that supply pre-stored power in an emergency when the power system is cut off.

In order to be used in such a wide range of applications, a lithium secondary battery having a higher energy density is being sought, and its development is in progress. In particular, since lithium secondary batteries for electric vehicles are required to have high safety in addition to high output and output characteristics and high energy density, higher-end technologies for ensuring safety are sought. As a method of improving the safety of a lithium secondary battery, a method of changing an electrolytic solution to a solid electrolyte is known (for example, Patent Document 1). [Prior Art Literature] (patent documents)

Patent Document 1: Japanese Patent Laid-Open No. 2004-107641

[Problem to be solved by the invention] In a lithium secondary battery using a solid electrolyte, it may be important to improve discharge characteristics when discharging is performed at a relatively low current of, for example, about 0.2 C, depending on the application. Accordingly, an object of the present invention is to provide a method of manufacturing a battery member for a secondary battery capable of improving discharge characteristics when the secondary battery is discharged with a relatively low current. [Technical means to solve the problem]

One aspect of the present invention provides a method for manufacturing a battery member for a secondary battery, which includes the following steps: forming an electrode mixture intermediate layer containing an electrode active material on one side of the current collector; and, forming an electrode mixture intermediate layer on the electrode mixture A step of coating a slurry containing oxide particles, a polymer, an ionic liquid, and an electrolyte salt on the side of the intermediate layer opposite to the collector; and, the total amount of the content of the ionic liquid and the electrolyte salt is relative to the oxidation The content of substance particles, in terms of volume ratio, is greater than 4/1 and less than 12/1.

The specific surface area of the oxide particles is preferably 2 to 400 m ² /g.

The concentration of the electrolyte salt per unit volume of the ionic liquid is preferably greater than 0.5 mol/L.

The ionic liquid preferably contains N(SO ₂ F) ₂ ^- as an anion component. [Efficacy of the invention]

According to the present invention, it is possible to provide a method of manufacturing a battery member for a secondary battery capable of improving discharge characteristics when the secondary battery is discharged with a relatively low current. More specifically, it is possible to provide a method for manufacturing a battery member for a secondary battery capable of improving the discharge characteristics of the secondary battery when discharging at 0.2C.

Hereinafter, embodiments of the present invention will be described with appropriate reference to the drawings. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including steps and the like) are not essential unless otherwise specified. The dimensions of the components in the drawings are conceptual dimensions, and the relative relationship of the dimensions between the components is not limited to those shown in the drawings.

The numerical values and their ranges in this specification are not intended to limit the present invention. The numerical range represented by "-" in this specification means the range which includes the numerical value described before and after "-" as a minimum value and a maximum value, respectively. In the numerical ranges described step by step in this specification, the upper limit value or lower limit value described in one numerical range may be replaced with the upper limit value or lower limit value described in other steps. In addition, in the numerical range described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in an Example.

In addition, the following abbreviations are sometimes used in this specification. [Py13] ⁺ : N-methyl-N-propylpyrrolidinium salt cation [EMI] ⁺ : 1-ethyl-3-methylimidazolium salt cation [DEME] ⁺ : N,N-diethyl- N-methyl-N-(2-methoxyethyl)ammonium cation [FSI] ^－ : N(SO ₂ F) ₂ ^－ , bis(fluorosulfonyl)imide anion [TFSI] ^－ : N(SO ₂ CF3) ₂ ^－ , bis(trifluoromethanesulfonyl)imide anion [f3C] ^－ : C(SO ₂ F) ₃ ^－ , ginseng(fluorosulfonyl)carbanion [BOB] ^－ : B(O ₂ C ₂ O ₂ ) ₂ ^－ , bisoxalate borate anion [P(DADMA)][Cl]: poly(diallyldimethylammonium chloride) [P(DADMA)][TFSI]: poly(diallyldimethyl Ammonium bis(trifluoromethanesulfonyl)imide salt)

Fig. 1 is a perspective view showing a secondary battery according to an embodiment. As shown in FIG. 1, a secondary battery 1 is provided with an electrode group 2 and a battery case 3. The electrode group 2 is composed of a positive electrode, a negative electrode, and an electrolyte layer. The battery case 3 is bag-shaped and accommodates the electrode group 2. . A positive electrode current collecting terminal (tab) 4 and a negative electrode current collecting terminal 5 are respectively provided on the positive electrode and the negative electrode. The positive electrode current collector terminal 4 and the negative electrode current collector terminal 5 protrude from the inside of the battery case 3 to the outside so that the positive electrode and the negative electrode can be electrically connected to the outside of the secondary battery 1 .

The battery case 3 can be formed using, for example, a laminated film. The laminated film may be, for example, a laminated film laminated in the following order: resin films such as polyethylene terephthalate (PET) films; metal foils such as aluminum, copper, and stainless steel; and polypropylene, etc. sealant layer.

FIG. 2 is an exploded perspective view showing an embodiment of the electrode group 2 of the secondary battery 1 shown in FIG. 1 . As shown in FIG. 2 , the electrode group 2A includes a positive electrode 6 , an electrolyte layer 7 , and a negative electrode 8 in this order. The positive electrode 6 includes a positive electrode current collector 9 and a positive electrode mixture layer 10 provided on the positive electrode current collector 9 . On the positive electrode current collector 9 of the positive electrode 6, the positive electrode current collector terminal 4 is provided. The negative electrode 8 includes a negative electrode current collector 11 and a negative electrode mixture layer 12 provided on the negative electrode current collector 11 . On the negative electrode current collector 11 of the negative electrode 8, the negative electrode current collector terminal 5 is provided.

In one embodiment, it can be considered that the first battery member (positive electrode member) for a secondary battery is included in the electrode group 2A, and the first battery member for a secondary battery is sequentially provided with a positive electrode current collector 9, a positive electrode Mixture layer 10 and electrolyte layer 7 . Similarly, it can also be regarded as including a second battery member for a secondary battery (negative electrode member) in the electrode group 2A, and the second battery member for a secondary battery is sequentially provided with a negative electrode current collector 11, a negative electrode mixture layer 12 and electrolyte layer 7. The method for manufacturing a battery member for a secondary battery (hereinafter sometimes simply referred to as “battery member”) according to each embodiment of the present invention is a method for manufacturing a positive electrode member or a negative electrode member.

Fig. 3 is a schematic cross-sectional view showing a method of manufacturing a battery member for a secondary battery according to an embodiment. This manufacturing method, as shown in Fig. 3 (a), is to form an electrode containing an electrode active material on one side (primary surface)) 13a of the current collector 13 (the positive electrode current collector 9 or the negative electrode current collector 11). Mixture intermediate layer 14 (positive electrode mixture intermediate layer or negative electrode mixture intermediate layer) (electrode mixture intermediate layer forming step).

In the step of forming the electrode mixture intermediate layer, in one embodiment, the method of forming the electrode mixture intermediate layer 14 on one side 13a of the current collector 13 is to apply the electrode mixture slurry on one side of the current collector 13 method on 13a. The electrode mixture slurry is a slurry obtained by dispersing the materials contained in the positive electrode mixture layer 10 or the negative electrode mixture layer 12 in a dispersion medium (positive electrode mixture slurry or negative electrode mixture slurry). The electrode mixture slurry of this embodiment contains at least an electrode active material (a positive electrode active material or a negative electrode active material) and a dispersion medium.

When the battery member is a positive electrode member, current collector 13 is positive electrode current collector 9 . The positive electrode current collector 9 may be metal such as aluminum, titanium, tantalum, or an alloy of these metals. In order to be lightweight and have high weight energy density, the positive electrode current collector 9 is preferably aluminum or its alloys. The thickness of positive electrode current collector 9 may be 10 μm or more, or 100 μm or less.

When the battery member is a negative electrode member, current collector 13 is negative electrode current collector 11 . The negative electrode current collector 11 may be a metal such as aluminum, copper, nickel, or stainless steel, an alloy of these metals, or the like. In order to be lightweight and have high gravimetric energy density, the negative electrode current collector 11 is preferably aluminum or its alloy. The negative electrode current collector 11 is preferably copper from the viewpoint of simplicity and cost of processing the thin film. The thickness of negative electrode current collector 11 may be 10 μm or more, or 100 μm or less.

When the battery member is a positive electrode member, the electrode active material is a positive electrode active material. The positive electrode active material may be a lithium transition metal compound such as a lithium transition metal oxide or a lithium transition metal phosphate.

Examples of lithium transition metal oxides include lithium manganese oxide, lithium nickel oxide, lithium cobalt oxide, and the like. Lithium transition metal oxides can be replaced by one or two or more other transition metals or metals (typical elements) such as magnesium (Mg) and aluminum (Al) to replace lithium manganate, lithium nickelate, lithium cobaltate, etc. A lithium transition metal oxide obtained from transition metals such as manganese (Mn), nickel (Ni), and cobalt (Co) contained in a part of the metal. That is, the lithium transition metal oxide may be a compound represented by LiM ¹ O ₂ or LiM ¹ O ₄ (M ¹ contains at least one transition metal). Lithium transition metal oxides, specifically, Li(Co _1/3 Ni _1/3 Mn _1/3 )O ₂ , LiNi _1/2 Mn _1/2 O ₂ , LiNi _1/2 Mn _3/2 O ₄ etc.

From the viewpoint of further improving the energy density, the lithium transition metal oxide is preferably a compound represented by the following formula (1). Li _a Ni _b Co _c M ² _d O _{2 + e} (1) In formula (1), M ² is at least one selected from the group consisting of Al, Mn, Mg and Ca, and a, b, c , d, and e are each a number satisfying 0.2≦a≦1.2, 0.5≦b≦0.9, 0.1≦c≦0.4, 0≦d≦0.2, -0.2≦e≦0.2, and b+c+d=1.

Lithium transition metal phosphate, which can be LiFePO ₄ , LiMnPO ₄ , LiMn _x M ³ _{1 - x} PO ₄ (0.3≦x≦1, M ³ is selected from Fe, Ni, Co, Ti, Cu, Zn, Mg and Zr at least one element in the group formed), etc.

The positive electrode active material may be ungranulated primary particles or granulated secondary particles.

The particle size of the positive electrode active material is adjusted to be equal to or less than the thickness of the positive electrode mixture layer 10 . When there is a kind of coarse particle having a particle size above the thickness of the positive electrode mixture layer 10 in the positive electrode active material, the coarse particles are removed in advance by sieve classification, air flow classification, etc., thereby screening the particle size below the thickness of the positive electrode mixture layer 10 positive active material.

The average particle diameter of the positive electrode active material is preferably at least 0.1 μm, more preferably at least 1 μm. The average particle diameter of the positive electrode active material is preferably 30 μm or less, more preferably 25 μm or less. The average particle diameter of the positive electrode active material is the particle diameter (D ₅₀ ) when the ratio (volume fraction) to the volume of the entire positive electrode active material is 50%. The average particle size (D ₅₀ ) of the positive electrode active material is to use a laser scattering particle size measuring device (such as Microtrac), and to measure the suspension according to the laser scattering method. The suspension is obtained by suspending the positive electrode active material in Made in water.

Based on the total amount of non-volatile components in the positive electrode mixture slurry (the components after excluding the dispersion medium from the positive electrode mixture slurry, the same below), the content of the positive electrode active material may be 70 mass % or more, 80 mass % or more , or 90 mass % or more, and may be 99 mass % or less. Thereby, the content of the positive electrode active material in the obtained positive electrode mixture layer can be set to the same content as the above-mentioned content.

When the battery member is a negative electrode member, the electrode active material is a negative electrode active material. As the negative electrode active material, negative electrode active materials commonly used in the field of energy devices can be used. As the negative electrode active material, specifically, for example: metal lithium, lithium titanate (Li ₄ Ti ₅ O ₁₂ ), lithium alloy or other metal compounds, carbon materials, metal complexes, and organic polymer compounds, etc. . The negative electrode active material may be a single type of these negative electrode active materials or a mixture of two or more types. Examples of carbon materials include: natural graphite (flaky graphite, etc.), artificial graphite and other graphite (graphite); amorphous carbon, carbon fiber; and, acetylene black, Ketjen black, channel black, furnace black, lamp black, etc. Black, thermal black and other carbon black, etc. From the viewpoint of obtaining a larger theoretical capacity (for example, 500-1500Ah/kg), the negative electrode active material can also be silicon, tin or compounds containing these elements (oxides, nitrides, alloys with other metals).

The average particle diameter (D ₅₀ ) of the negative electrode active material is preferably 1 μm or more from the viewpoint of obtaining a well-balanced negative electrode that suppresses an increase in irreversible capacity accompanying particle size reduction and improves electrolyte salt retention. , more preferably 5 μm or more, further preferably 10 μm or less, and, preferably 50 μm or less, more preferably 40 μm or less, further preferably 30 μm or less. The average particle diameter (D ₅₀ ) of the negative electrode active material is measured by the same method as the average particle diameter (D ₅₀ ) of the above positive electrode active material.

Based on the total amount of non-volatile components in the negative electrode mixture slurry (the components after excluding the dispersion medium from the negative electrode mixture slurry, the same below), the content of the negative electrode active material can be 60 mass % or more, 65 mass % or more , or 70% by mass or more, and may be 99% by mass or less, 95% by mass or less, or 90% by mass or less. Thereby, the content of the negative electrode active material in the obtained negative electrode mixture layer can be set to the same content as the above-mentioned content.

Dispersion medium can be water or organic solvent. Organic solvents, such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide, methyl ethyl ketone, toluene, 2-butanol, cyclohexanone, ethyl acetate, 2-propane alcohol etc., preferably NMP. The content of the dispersion medium in the electrode mixture slurry can be, for example, 20 parts by mass relative to 100 parts by mass of the non-volatile components in the electrode mixture slurry (the components except the dispersion medium from the electrode mixture slurry, the same below). The above may be 1000 parts by mass or less.

The electrode mixture slurry may further contain a conductive agent, a binder, and the like as other components. In this case, the electrode mixture intermediate layer 14 further containing these materials can be formed.

The conductive agent is not particularly limited, and may be carbon materials such as graphite, acetylene black, carbon black, carbon fiber, and carbon nanotubes. The conductive agent may be a mixture of two or more of the above carbon materials. Based on the total amount of non-volatile components in the electrode mixture slurry, the content of the conductive agent may be 1-70% by mass. Thereby, the content of the conductive agent in the obtained electrode mixture layer can be set to the same content as the above-mentioned content.

The binder is not particularly limited, and may be: a polymer consisting of tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate and methyl methacrylate At least one of the group of monomers used as a monomer unit; rubber such as styrene-butadiene rubber, isoprene rubber, acrylic rubber, and the like. The binder is preferably a copolymer comprising hexafluoropropylene and vinylidene fluoride as structural units. Based on the total amount of non-volatile components in the electrode mixture slurry, the content of the binder may be 1-70% by mass. Thereby, the content of the binder in the obtained electrode mixture layer can be the same as the content mentioned above.

The electrode mixture slurry may further include the following ionic liquid and electrolyte salt, but preferably does not contain ionic liquid and electrolyte salt.

In the electrode mixture intermediate layer forming step, examples of the method of applying the electrode mixture slurry include a method of applying using a coater, a method of applying by spraying, and the like. According to these methods, the electrode mixture slurry is coated on one surface 13 a of the current collector 13 . As a result, as shown in FIG. 3( a ), an electrode mixture intermediate layer 14 is formed on one surface 13 a of the current collector 13 .

In the step of forming the electrode mixture intermediate layer, after coating the electrode mixture slurry, the dispersion medium in the slurry may be volatilized. That is, the "intermediate layer of the electrode mixture" in this specification includes a layer formed of the electrode mixture and a layer formed by volatilizing part or all of the dispersion medium from the electrode mixture slurry. The method of volatilizing the dispersion medium may be, for example, a method of drying by heating, a method of reducing pressure, or a method of combining pressure reduction and heating. In the method of reducing the pressure, the pressure can be reduced to a vacuum state. The heating temperature at the time of drying may be 50 to 150°C. The heating time may be changed according to the temperature as long as the dispersion medium is sufficiently volatilized, and may be, for example, 1 minute to 48 hours.

After the electrode mixture intermediate layer forming step, as shown in Fig. 3 (b), on the surface 14a of the side 14a opposite to the current collector 13 of the electrode mixture intermediate layer 14, coatings containing oxide particles 16, polymers 17, Slurry 15 of ionic liquid, electrolyte salt and dispersion medium. Hereinafter, this slurry is also referred to as "electrolyte slurry", and the step of applying the electrolyte slurry 15 is also referred to as "electrolyte slurry coating step".

The oxide particles 16 are, for example, inorganic oxide particles. The inorganic oxide, for example, may be an inorganic oxide containing Li, Mg, Al, Si, Ca, Ti, Zr, La, Na, K, Ba, Sr, V, Nb, B, Ge, etc. as constituent elements . _{The oxide particles 16 are preferably at least _ _} 1 particle. Oxide particles 16 have polarity, so they can promote dissociation of the electrolyte in the electrolyte and improve battery characteristics.

The oxide particles 16 may be oxides of rare earth metals. The oxide particles 16, specifically, may be scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, cerium oxide, rubidium oxide, samarium oxide, europium oxide, cerium oxide, cerium oxide, dysprosium oxide, erbium oxide, erbium oxide, Iron oxide, ytterbium oxide, lutetium oxide, etc.

The oxide particles 16 may have a hydrophobic surface. Oxide particles 16 generally have a hydroxyl group on their surface and tend to exhibit hydrophilicity. Oxide particles with a hydrophobic surface have fewer hydroxyl groups on the surface than oxide particles without a hydrophobic surface. Therefore, if oxide particles having a hydrophobic surface are used, the ionic liquid will be hydrophobic, and thus the affinity between the oxide and the ionic liquid is expected to be improved. Therefore, it is considered that the liquid retention property of the ionic liquid in the electrolyte layer 7 is further improved, and as a result, the ionic conductivity of the electrolyte layer 7 is improved. When oxide particles having a hydrophobic surface are used, the discharge characteristics can be improved not only when the secondary battery is discharged at a relatively low current but also at a relatively high current (for example, about 0.5C).

The oxide particles having a hydrophobic surface can be obtained, for example, by treating the oxide particles exhibiting hydrophilicity with a surface treatment agent capable of imparting a hydrophobic surface. That is, oxide particles having a hydrophobic surface mean oxide particles surface-treated with a surface treatment agent. As the surface treatment agent, a silicon-containing compound or the like may be used.

The oxide particles 16 can be surface treated with a silicon-containing compound. That is, the oxide particle 16 can connect the surface of the oxide particle and the silicon atoms of the silicon-containing compound via oxygen atoms. The silicon-containing compound is preferably at least one selected from the group consisting of halogen-containing alkylsilanes, alkoxysilanes, epoxy-containing silanes, amino-containing silanes, silazanes, and siloxanes.

The halogen element in the halogen-containing alkylsilane can be chlorine, fluorine, etc. The chlorine-containing halogen-containing alkylsilane (alkylchlorosilane) can be methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, n-octyldimethylchlorosilane, etc. The fluorine-containing halogen-containing alkylsilane (fluoroalkylsilane) may be trifluoropropyltrimethoxysilane, tridecylfluorooctyltrimethoxysilane, etc.

Alkoxysilane, which can be methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxydiphenylsilane, n-propyltrimethylsilane Oxysilane, Hexyltrimethoxysilane, Tetraethoxysilane, Methyltriethoxysilane, Dimethyldiethoxysilane, n-Propyltriethoxysilane, etc.

Epoxy-containing silane, which can be 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-epoxypropyl Oxypropyltrimethoxysilane, 3-Glycidoxypropylmethyldiethoxysilane, 3-Glycidoxypropyltriethoxysilane, etc.

Amino-containing silane, which can be N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, etc.

Silazane can be hexamethyldisilazane or the like. Siloxane can be dimethyl silicone oil and the like. Such silicon-containing compounds having reactive functional groups (such as carboxyl groups) at one or both ends may be used.

As the oxide particles having a hydrophobic surface (surface-treated oxide particles), oxide particles produced by a known method may be used, or commercially available products may be used as they are.

Oxide particles 16 may include primary particles (particles that do not constitute secondary particles) and secondary particles formed by aggregating a plurality of primary particles. The primary particles are generally integrally formed judging from the geometric shape of the appearance single particle.

The specific surface area of the oxide particles 16 is preferably 2 to 400 m ² /g, 5 to 100 m ² /g, 10 to 80 m ² /g, or 15 to 60 m ² /g. When the specific surface area is 2 to 400 m ² /g, a secondary battery provided with an electrolyte layer containing such oxide particles tends to have better discharge characteristics. From the same viewpoint, the specific surface area of the oxide particles 16 may be 2 m ² /g or more, 5 m ² /g or more, 10 m ² /g or more, 15 m ² /g, or 50 m ² /g or more, or may be It is 400m ² /g or less, 350m ² /g or less, 300m 2 /g or less, 200m ² /g or less, 100m ^{2 /} g or less, 90m ² /g or less, 80m ² /g or less, or 60m ² /g or less. The specific surface area of the oxide particle 16 means the specific surface area of the entire oxide particle including primary particles and secondary particles, and is measured by the BET method.

From the viewpoint of further improving the electrical conductivity of the secondary battery 1, the average primary particle size (average particle size of primary particles) of the oxide particles 16 is preferably 0.005 μm (5 nm) or more, more preferably 0.01 μm (10 nm). ) or more, more preferably 0.015 μm (15 nm) or more. From the viewpoint of thinning the electrolyte layer 7, the average primary particle diameter of the oxide particles 16 is preferably 1 μm or less, more preferably 0.1 μm or less, further preferably 0.05 μm or less. The average primary particle diameter of the oxide particles 16 can be measured by observing the oxide particles 16 with a transmission electron microscope or the like.

The average particle diameter of the oxide particles 16 is preferably at least 0.005 μm, more preferably at least 0.01 μm, and even more preferably at least 0.03 μm. The average particle diameter of the oxide particles 16 is preferably 5 μm or less, more preferably 3 μm or less, further preferably 1 μm or less. The average particle diameter of the oxide particles 16 is measured by the laser diffraction method, and corresponds to the particle diameter at which the volume accumulation reaches 50% when the volume accumulation particle size distribution curve is drawn from the small particle diameter side.

The content of the oxide particles 16 is preferably 1% by mass or more, more preferably 3% by mass, based on the total amount of non-volatile components of the electrolyte slurry 15 (the components of the electrolyte slurry excluding the dispersion medium, the same below). % by mass or more, more preferably at least 5 mass %, particularly preferably at least 7 mass %, and preferably at most 30 mass %, more preferably at most 27 mass %, even more preferably at most 25 mass %.

In the electrolyte slurry 15, based on the total amount of non-volatile components of the electrolyte slurry 15, the content of the oxide particles 16 is preferably 5% by volume or more, more preferably 7% by volume or more, and even more preferably 9% by volume. vol% or more, and preferably 20 vol% or less, more preferably 17 vol% or less, further preferably 15 vol% or less.

The polymer 17 preferably has a first structural unit selected from the group consisting of tetrafluoroethylene and vinylidene fluoride.

The polymer 17 is preferably 1 type or 2 or more types of polymers. Among the structural units constituting one or more polymers may include: the above-mentioned first structural unit; and, a second structural unit selected from the group consisting of hexafluoropropylene, acrylic acid, maleic acid, and ethyl methacrylate And in the group consisting of methyl methacrylate. That is, the first structural unit and the second structural unit may be included in one polymer to form a copolymer, or may be included in different polymers to form the first polymer having the first structural unit and the first polymer having A polymer of at least two types of the second polymer of the second structural unit.

Specifically, the polymer 17 may be polytetrafluoroethylene, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, or the like.

Based on the total amount of non-volatile components in the electrolyte slurry 15, the content of the polymer 17 is preferably at least 3% by mass, and is preferably at most 60% by mass, more preferably at most 50% by mass, and even more preferably It is 40 mass % or less.

The ionic liquid contains the following anionic components and cationic components. In addition, the ionic liquid in this specification is a substance which becomes liquid at -20 degreeC or more. In the secondary battery 1 , the types of ionic liquid contained in the positive electrode member and the negative electrode member may be the same or different.

The anion component of the ionic liquid is not particularly limited, and it can be the anion of halogen such as Cl ^- , Br ^- , I ^-, etc.; the inorganic anion of BF ₄ ^- , N(SO ₂ F) ₂ ^-, etc.; B(C ₆ H ₅ ) ₄ ^- , CH ₃ SO ₂ O ^- , CF ₃ SO ₂ O ^- , N(SO ₂ C ₄ F ₉ ) ₂ ^- , N(SO ₂ CF ₃ ) ₂ ^- , N(SO ₂ C ₂ F ₅ ) ₂ ^- and other organic anions. The anionic component of the ionic liquid preferably contains at least one anionic component represented by the following general formula (2). N(SO ₂ C _m F _{2m + 1} )(SO ₂ C _n F _{2n + 1} ) ^- (2) In formula (2), m and n each independently represent an integer of 0-5. m and n may be the same or different from each other, and are preferably the same.

Anion components represented by formula (2) are, for example, N(SO ₂ C ₄ F ₉ ) ₂ ^- , N(SO ₂ F) ₂ ^- , N(SO ₂ CF ₃ ) ₂ ^- and N(SO ₂ C ₂ F ₅ ) _2- ^. From the point of view of relatively low viscosity, further improvement of ionic conductivity, and further improvement of charge-discharge characteristics, the ionic component of the ionic liquid is preferably composed of N(SO ₂ C ₄ F ₉ ) ₂ ^- , CF ₃ At least one selected from the group consisting of SO ₂ O ^- , N(SO ₂ F) ₂ ^- , N(SO ₂ CF ₃ ) ₂ ^- , and N(SO ₂ C ₂ F ₅ ) ₂ ^- .

The electrolyte slurry 15 further preferably contains N(SO ₂ F) ₂ ⁻ as an anion component. When N(SO ₂ F) ₂ ⁻ is contained as an anion component, a favorable interface can be formed between the electrode mixture layer and the electrolyte layer in the obtained battery member. This effect is particularly remarkable in the negative electrode member. That is, in the method of manufacturing the negative electrode member, the ionic liquid contained in the electrolyte slurry preferably contains N(SO ₂ F) ₂ ⁻ as an anion component.

The cationic component of the ionic liquid is preferably selected from the group consisting of chain quaternary onium salt cations, piperidinium salt cations, pyrrolidinium salt cations, pyridinium salt cations and imidazolium cations (imidazolium cation) at least 1 species of .

式(3)中，R¹ ～R⁴ 各自獨立地表示碳數為1～20的鏈狀烷基或由R-O-(CH₂ )_n -表示的鏈狀烷氧烷基(R表示甲基或乙基，n表示1～4的整數)，X表示氮原子或磷原子。由R¹ ～R⁴ 表示的烷基的碳數較佳是1～20，更佳是1～10，進一步更佳是1～5。The chain quaternary onium salt cation is, for example, a compound represented by the following formula (3).

In formula (3), R ¹ to R ⁴ each independently represent a chained alkyl group having 1 to 20 carbons or a chained alkoxyalkyl group represented by RO-(CH ₂ ) _n - (R represents methyl or ethyl group, n represents an integer of 1 to 4), and X represents a nitrogen atom or a phosphorus atom. The number of carbon atoms in the alkyl group represented by R ¹ to R ⁴ is preferably 1-20, more preferably 1-10, and still more preferably 1-5.

式(4)中，R⁵ 和R⁶ 各自獨立地表示碳數為1～20的烷基或由R-O-(CH₂ )_n -表示的烷氧烷基(R表示甲基或乙基，n表示1～4的整數)。由R⁵ 和R⁶ 表示的烷基的碳數較佳是1～20，更佳是1～10，進一步更佳是1～5。The piperidinium salt cation is, for example, a nitrogen-containing six-membered ring compound represented by the following formula (4).

In formula (4), R ⁵ and R ⁶ each independently represent an alkyl group with 1 to 20 carbon atoms or an alkoxyalkyl group represented by RO-(CH ₂ ) _n - (R represents methyl or ethyl, n represents an integer of 1 to 4). The carbon number of the alkyl group represented by R ⁵ and R ⁶ is preferably 1-20, more preferably 1-10, further preferably 1-5.

式(5)中，R⁷ 和R⁸ 各自獨立地表示碳數為1～20的烷基或由R-O-(CH₂ )_n -表示的烷氧烷基(R表示甲基或乙基，n表示1～4的整數)。由R⁷ 和R⁸ 表示的烷基的碳數較佳是1～20，更佳是1～10，進一步更佳是1～5。The pyrrolidinium salt cation is, for example, a five-membered ring compound represented by the following formula (5).

In formula (5), R ⁷ and R ⁸ each independently represent an alkyl group with 1 to 20 carbon atoms or an alkoxyalkyl group represented by RO-(CH ₂ ) _n - (R represents methyl or ethyl, n represents an integer of 1 to 4). The number of carbon atoms in the alkyl group represented by R ⁷ and R ⁸ is preferably 1-20, more preferably 1-10, and still more preferably 1-5.

式(6)中，R⁹ ～R¹³ 各自獨立地表示碳數為1～20的烷基、由R-O-(CH₂ )_n -表示的烷氧烷基(R表示甲基或乙基，n表示1～4的整數)、或氫原子。由R⁹ ～R¹³ 表示的烷基的碳數較佳是1～20，更佳是1～10，進一步更佳是1～5。The pyridinium salt cation is, for example, a compound represented by the following formula (6).

In formula (6), R ⁹ to R ¹³ each independently represent an alkyl group having 1 to 20 carbon atoms, an alkoxyalkyl group represented by RO-(CH ₂ ) _n - (R represents methyl or ethyl, n represents an integer of 1 to 4), or a hydrogen atom. The number of carbon atoms in the alkyl group represented by R ⁹ to R ¹³ is preferably 1-20, more preferably 1-10, and still more preferably 1-5.

式(7)中，R¹⁴ ～R¹⁸ 各自獨立地表示碳數為1～20的烷基、由R-O-(CH₂ )_n -表示的烷氧烷基(R表示甲基或乙基，n表示1～4的整數)、或氫原子。由R¹⁴ ～R¹⁸ 表示的烷基的碳數較佳是1～20，更佳是1～10，進一步更佳是1～5。The imidazolium salt cation is, for example, a compound represented by the following formula (7).

In formula (7), R ¹⁴ to R ¹⁸ each independently represent an alkyl group having 1 to 20 carbon atoms, an alkoxyalkyl group represented by RO-(CH ₂ ) _n - (R represents methyl or ethyl, n represents an integer of 1 to 4), or a hydrogen atom. The number of carbon atoms in the alkyl group represented by R ¹⁴ to R ¹⁸ is preferably 1-20, more preferably 1-10, still more preferably 1-5.

The ionic liquid contained in the electrolyte slurry 15 is preferably N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium-bis(trifluoromethanesulfonyl)imide ( DEME-TFSI), N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium-bis(fluorosulfonyl)imide (DEME-FSI), 1-ethyl- 3-methylimidazolium-bis(trifluoromethanesulfonyl)imide (EMI-TFSI), 1-ethyl-3-methylimidazolium-bis(fluorosulfonyl)imide (EMI-FSI), N -Methyl-N-propylpyrrolidinium-bis(trifluoromethanesulfonyl)imide (Py13-TFSI), N-methyl-N-propylpyrrolidinium-bis(fluorosulfonyl)imide ( Py13-FSI), N-ethyl-N-methylpyrrolidinium-bis(trifluoromethanesulfonyl)imide (Py12-TFSI), or N-ethyl-N-methylpyrrolidinium-bis( Fluorosulfonyl)imine (Py12-FSI). From the viewpoint of further improving the discharge characteristics at a relatively high current, the ionic liquid contained in the electrolyte slurry 15 is more preferably DEME-FSI, EMI-FSI, Py13-FSI, or Py12-FSI. From the viewpoint of further improving the discharge characteristics at a relatively high current, the ionic liquid contained in the electrolyte slurry 15 is further preferably EMI-FSI.

The electrolyte salt may be at least one selected from the group consisting of lithium salts, sodium salts, calcium salts, and magnesium salts.

The anion component of the electrolyte salt can be halide ions (I ^- , Cl ^- , Br ^-, etc.), SCN ^- , BF ₄ ^- , BF ₃ (CF ₃ ) ^- , BF ₃ (C ₂ F ₅ ) ^- , PF ₆ ^－ , ClO ₄ ^－ , SbF ₆ ^－ , N(SO ₂ F) ₂ ^－ , N(SO ₂ CF ₃ ) ₂ ^－ , N(SO ₂ C ₂ F ₅ ) ₂ ^－ , B(C ₆ H ₅ ) ₄ ^－ , B(O ₂ C ₂ H ₄ ) ₂ ^－ , C(SO ₂ F) ₃ ^－ , C(SO ₂ CF ₃ ) ₃ ^－ , CF ₃ COO ^－ , CF ₃ SO ₂ O ^－ , C ₆ F ₅ SO ₂ O ^－ , B(O ₂ C ₂ O ₂ ) ₂ ^－ , etc. Anion components of the electrolyte salt are preferably: N(SO ₂ F) ₂ ^- , N(SO ₂ CF ₃ ) ₂ ^- and the like represented by the above formula (2); PF ₆ ^- , BF ₄ ^- , B (O ₂ C ₂ O ₂ ) ₂ ⁻ , or ClO ₄ ⁻ .

Lithium salt, can be selected from LiPF ₆ , LiBF ₄ , Li[FSI], Li[TFSI], Li[f3C], Li[BOB], LiClO ₄ , LiBF ₃ (CF ₃ ), LiBF ₃ (C ₂ F ₅ ), LiBF ₃ (C ₃ F ₇ ), LiBF ₃ (C ₄ F ₉ ), LiC(SO ₂ CF ₃ ) ₃ , LiCF ₃ SO ₂ O, LiCF ₃ COO, and LiRCOO (R is carbon number 1-4 at least one of the group consisting of alkyl, phenyl, or naphthyl).

The sodium salt may be selected from NaPF ₆ , NaBF ₄ , Na[FSI], Na[TFSI], Na[f3C], Na[BOB], NaClO ₄ , NaBF ₃ (CF ₃ ), NaBF ₃ (C ₂ F ₅ ), NaBF ₃ (C ₃ F ₇ ), NaBF ₃ (C ₄ F ₉ ), NaC(SO ₂ CF ₃ ) ₃ , NaCF ₃ SO ₂ O, NaCF ₃ COO, and NaRCOO (R is carbon number 1-4 at least one of the group consisting of alkyl, phenyl, or naphthyl).

A calcium salt, which may be selected from the group consisting of Ca(PF ₆ ) ₂ , Ca(BF ₄ ) ₂ , Ca[FSI] ₂ , Ca[TFSI] ₂ , Ca[f3C] ₂ , Ca[BOB] ₂ , Ca(ClO ₄ ) ₂ , Ca[BF ₃ (CF ₃ )] ₂ , Ca[BF ₃ (C ₂ F ₅ )] ₂ , Ca[BF ₃ (C ₃ F ₇ )] ₂ , Ca[BF ₃ (C ₄ F ₉ )] _2. Ca[C(SO ₂ CF ₃ ) ₃ ] ₂ , Ca(CF ₃ SO ₂ O) ₂ , Ca(CF ₃ COO) ₂ , and Ca(RCOO) ₂ (R is an alkane with 1 to 4 carbons at least one of the group consisting of phenyl, naphthyl, or naphthyl).

A magnesium salt, which may be selected from Mg(PF ₆ ) ₂ , Mg(BF ₄ ) ₂ , Mg[FSI] ₂ , Mg[TFSI] ₂ , Mg[f3C] ₂ , Mg[BOB] ₂ , Mg(ClO ₄ ) ₂ , Mg[BF ₃ (CF ₃ )] ₂ , Mg[BF ₃ (C ₂ F ₅ )] ₂ , Mg[BF ₃ (C ₃ F ₇ )] ₂ , Mg[BF ₃ (C ₄ F ₉ )] _2. Mg[C(SO ₂ CF ₃ ) ₃ ] ₂ , Mg(CF ₃ SO ₃ ) ₂ , Mg(CF ₃ COO) ₂ , and Mg(RCOO) ₂ (R is an alkyl group with 1 to 4 carbons , phenyl, or naphthyl) at least one of the group consisting of.

Among them, from the standpoint of dissociation and electrochemical stability, the electrolyte salt is preferably selected from LiPF ₆ , LiBF ₄ , Li[FSI], Li[TFSI], Li[f3C], Li[BOB], LiClO _4. LiBF ₃ (CF ₃ ), LiBF ₃ (C ₂ F ₅ ), LiBF ₃ (C ₃ F ₇ ), LiBF ₃ (C ₄ F ₉ ), LiC(SO ₂ CF ₃ ) ₃ , LiCF ₃ SO ₂ O , LiCF ₃ COO, and LiRCOO (R is an alkyl group with 1 to 4 carbons, phenyl, or naphthyl), more preferably selected from Li[TFSI], Li[ At least one selected from the group consisting of FSI], LiPF ₆ , LiBF ₄ , Li[BOB], and LiClO ₄ , more preferably selected from the group consisting of Li[TFSI] and Li[FSI] At least 1 species.

The electrolyte slurry may contain an ionic liquid and an electrolyte salt as an "ionic liquid electrolyte solution" obtained by dissolving an electrolyte salt in an ionic liquid. In the ionic liquid electrolyte, the salt concentration of the electrolyte salt per unit volume of the ionic liquid is preferably greater than 0.5 mol/L. By making the salt concentration of the electrolyte salt per unit volume of the ionic liquid greater than 0.5 mol/L, even in the case of discharging the secondary battery with a relatively high current (for example, in the case of discharging at 0.5C), it is possible to The discharge characteristics of the secondary battery are improved, and as a result, the discharge characteristics of the secondary battery can be further improved. From the same viewpoint, the salt concentration of the electrolyte salt per unit volume of the ionic liquid is more preferably 0.7 mol/L or higher, and further preferably 1.0 mol/L or higher. From the viewpoint of suppressing the decrease in ionic conductivity due to the inclusion of too much electrolyte salt, the salt concentration of the electrolyte salt per unit volume of the ionic liquid is preferably 3.0 mol/L or less, more preferably 2.7 mol/L or less, More preferably, it is 2.5 mol/L or less.

From the viewpoint of obtaining a uniform dispersion state in the electrolyte slurry 15 and the excellent formation of the interface between the electrode mixture layer (positive electrode mixture layer 10 or negative electrode mixture layer 12) and the electrolyte layer 7, the Based on the total amount of non-volatile components, the content of the ionic liquid electrolyte (the total amount of the content of the ionic liquid and the electrolyte salt) is preferably 20% by mass or more, more preferably 25% by mass or more, and more preferably 30% by mass %above. Thereby, the ionic conductivity of the electrolyte layer 7 can be improved, and the battery characteristics of the secondary battery can be further improved. Based on the total amount of non-volatile components in the electrolyte slurry 15 , the content of the ionic liquid electrolyte may be 90% by mass or less, 85% by mass or less, or 80% by mass or less.

For the electrolyte slurry 15, from the viewpoint of obtaining a uniform dispersion state in the electrolyte slurry 15 and the viewpoint of forming the interface between the electrode mixture layer (positive electrode mixture layer 10 or negative electrode mixture layer 12) and the electrolyte layer 7 well, The total amount of non-volatile components in the electrolyte slurry 15 is used as a reference, and the content of the ionic liquid electrolyte (the total amount of the content of the ionic liquid and the electrolyte salt) is preferably 35% by volume or more, more preferably 40% by volume or more, More preferably, it is 45 volume% or more. Thereby, the ionic conductivity of the electrolyte layer 7 can be improved, and the battery characteristics of the secondary battery can be further improved. Based on the total amount of non-volatile components in the electrolyte slurry 15 , the content of the ionic liquid electrolyte may be less than 90% by volume, less than 85% by volume, or less than 80% by volume.

The dispersion medium in the electrolyte slurry 15 may be the same as the above-mentioned dispersion medium used in the electrode mixture slurry. The content of the dispersion medium in the electrolyte slurry 15 may be, for example, 5 parts by mass or more and may be 1000 parts by mass or less with respect to 100 parts by mass of non-volatile components in the electrode mixture slurry 15 .

In the electrolyte slurry 15, the ratio of the total amount of the content of the ionic liquid and the electrolyte salt to the content of the oxide particles 16 is greater than 4/ 1 and less than 12/1. Thereby, it is possible to improve the discharge characteristics of the secondary battery when the secondary battery is discharged at a relatively low current (for example, at 0.2C). The ratio of the total content of the ionic liquid and the electrolyte salt to the content of the oxide particles 16 is preferably 5/1 or more, more preferably 6/1 or more, in terms of volume ratio. In order to suppress the deterioration of the properties of the electrolyte slurry due to the high content of the ionic liquid and the electrolyte salt, or to suppress the leakage of the liquid from the electrode after drying, the total amount of the content of the ionic liquid and the electrolyte salt, relative to the oxide The ratio of the content of the particles 16 is preferably 11/1 or less, more preferably 10/1 or less, further preferably 9/1 or less, and most preferably 8/1 or less in volume ratio.

In the electrolyte slurry 15, from the viewpoint of enhancing the strength of the electrolyte layer, the ratio of the content of the oxide particles 16 to the content of the polymer 17 is preferably expressed as a mass ratio (content of oxide particles/polymer content) is 1/5 or more, more preferably 1/4 or more, further preferably 1/3 or more, and most preferably 1/2 or more. From the viewpoint of improving discharge characteristics at a relatively high current, the ratio of the content of the oxide particles 16 to the content of the polymer 17 is preferably 5/1 or less, more preferably 3/1 in terms of mass ratio. 1 or less, more preferably 1/1 or less, and most preferably 2/3 or less.

In the electrolyte slurry 15, the content ratio of the oxide particles 16, the polymer 17, and the ionic liquid electrolyte may be, in terms of mass ratio, oxide particles:polymer:ionic liquid electrolyte=7～25:4～60 : 20-85.

In the electrolyte slurry coating step, the method of coating the electrolyte slurry 15 on one side (main surface) 14a of the electrode mixture intermediate layer 14 can be compared with the above-mentioned method of coating the electrode mixture slurry on the current collector 13. The method on one side 13a is the same. The method of coating the electrolyte slurry 15 may be the same as the method of coating the electrode mixture, or it may be different.

After the electrolyte slurry coating step, the dispersion medium contained in the electrode mixture intermediate layer 14 and the electrolyte slurry 15 is volatilized. The method of volatilizing the dispersion medium may be the same as the above-mentioned method of volatilizing the dispersion medium in the electrode mixture slurry. As a result of volatilizing the dispersion medium of the electrode mixture intermediate layer 14 and the electrolyte slurry 15, as shown in Fig. 3 (c), a battery member 19 (positive electrode member or negative electrode member) for a secondary battery can be obtained, which is sequentially It includes a current collector 13 , an electrode mixture layer 18 (the positive electrode mixture layer 10 or the negative electrode mixture layer 12 ), and the electrolyte layer 7 .

The secondary battery obtained by using the battery member 19 obtained by the manufacturing method of this embodiment is particularly excellent in discharge characteristics when the secondary battery is charged with a relatively low current.

Also, in the manufacturing method of this embodiment, when the electrolyte slurry 15 is coated on the electrode mixture intermediate layer 14, as shown by the arrow in Fig. 3 (b), the ionic liquid electrolyte will flow from Electrolyte slurry 15 moves to electrode mixture intermediate layer 14 . It is presumed that this movement is due to the action of reducing the concentration difference of the ionic liquid electrolyte between the electrode mixture intermediate layer 14 and the electrolyte slurry 15 , the action due to gravity, or the capillary phenomenon.

According to the production method of this embodiment, since the electrolyte layer 7 is formed by coating the electrolyte slurry 15 on the electrode mixture intermediate layer 14, even if there are fine irregularities on the surface of the electrode mixture intermediate layer 14, they can still be filled. Electrolyte paste 15 is disposed so as to flatten the concave portion. As a result, in the obtained battery member 19 , a favorable interface in which the electrode mixture layer 18 and the electrolyte layer 7 are in close contact is formed. Also, in the battery member 19, in the electrolyte slurry coating step, the ionic liquid electrolyte can move between the electrolyte slurry 15 and the electrode mixture intermediate layer 14, so in the electrode mixture layer 18, the ionic liquid electrolyte becomes It is easy to exist around the electrode active material. Therefore, in the battery member 19 , an electrode active material/electrolyte interface can be favorably formed.

In this way, in the battery member 19, the interface of the electrode active material 18/electrolyte 7 can be formed favorably, and the adhesiveness is excellent, and the interface of the electrode active material/electrolyte can also be formed favorably. Therefore, the battery characteristics of the secondary battery obtained using this battery member 19 are further excellent.

As another embodiment, the manufacturing method of the secondary battery may further include the step of soaking the solution (polymer solution) containing the polymer into the electrode mixture intermediate layer 14 before coating the electrolyte slurry 15 (polymer solution soaking step).

In one embodiment, the polymer solution contains a polymer having a structural unit represented by the following formula (8), an ionic liquid, and an electrolyte salt.

In formula (8), X ⁻ represents a relative anion. Examples of X ^- include: BF ₄ ^- (tetrafluoroborate anion), PF ₆ ^- (hexafluorophosphate anion), [FSI] ^- , [TFSI] ^- , [f3C] ^- , [BOB] ^- , BF ₃ (CF ₃ ) ^- , BF ₃ (C ₂ F ₅ ) ^- , BF ₃ (C ₃ F ₇ ) ^- , BF ₃ (C ₄ F ₉ ) ^- , C(SO ₂ CF ₃ ) ₃ ^- , CF ₃ SO ₂ O ^- , CF ₃ COO ^- , RCOO ^- (R is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group) and the like. Among them, X ^- is preferably at least one selected from the group consisting of BF ₄ ^- , PF ₆ ^- , [FSI] ^- , [TFSI] ^- , [f3C] ^- , more preferably [TFSI] ^- or [FSI] ^- .

The viscosity average molecular weight Mv (g･mol ⁻¹ ) of the polymer having the structural unit represented by formula ( ⁸ ) is not particularly limited, but is preferably 1.0×10 ⁵ or more, more preferably 3.0×10 ⁵ or more. The viscosity average molecular weight of the polymer is preferably at most 5.0×10 ⁶ , more preferably at most 1.0×10 ⁶ . When the viscosity average molecular weight of the polymer is 5.0×10 ⁶ or less, the handling property at the time of impregnating the polymer solution tends to be further improved.

In this specification, "viscosity average molecular weight" refers to a general measurement method that can be evaluated by a viscosity method, for example, an intrinsic viscosity number that can be measured based on Japanese Industrial Standards (JIS) K 7367-3:1999[ η] to calculate.

From the viewpoint of ion conductivity, the polymer having the structural unit represented by formula (8) is preferably a polymer composed of only the structural unit represented by formula (8), that is, a homopolymer.

The polymer having a structural unit represented by formula (8) may be a polymer represented by formula (8A).

In the formula (8A), n is 300-400, and Y ^- represents a relative anion. Y ^- can use the same relative anion as exemplified by X ^- .

n is 300 or more, preferably 400 or more, more preferably 500 or more, and may be 4000 or less, preferably 3500 or less, more preferably 3000 or less. n is 300-4000, preferably 400-3500, more preferably 500-3000.

The production method of the polymer having the structural unit represented by formula (8) is not particularly limited, and for example, the production method described in Journal of Power Sources 2009, 188, 558-563 can be used.

A polymer (X ⁻ =[TFSI] ⁻ ) having a structural unit represented by formula (8) can be obtained by, for example, the following production method.

First, poly(diallyldimethylammonium chloride) ([P(DADMA)][Cl]) was dissolved in deionized water and stirred to prepare an aqueous solution of [P(DADMA)][Cl]. [P(DADMA)][Cl], for example, a commercially available product can be used as it is. Next, Li[TFSI] was separately dissolved in deionized water to prepare an aqueous solution containing Li[TFSI].

Then, the molar ratio of Li[TFSI] to [P(DADMA)][Cl] (molar amount of Li[TFSI]/molar amount of [P(DADMA)][Cl]) is 1.2 to 2.0 The two aqueous solutions were mixed in the same manner and stirred for 2 to 8 hours to precipitate a solid, and then the obtained solid was recovered by filtration. The solid was washed with deionized water and vacuum-dried for 12 to 48 hours, whereby a polymer ([P(DADMA)][TFSI]) having a structural unit represented by formula (8) could be obtained.

Based on the total amount of the polymer solution, the polymer having a structural unit represented by formula (8) is preferably at least 10% by mass, more preferably at least 20% by mass, further preferably at least 30% by mass, and , preferably at most 80% by mass, more preferably at most 75% by mass, further preferably at most 70% by mass.

The ionic liquid and electrolyte contained in the polymer solution may be the same as the ionic liquid and electrolyte that can be used in the above-mentioned embodiment. The ionic liquid and electrolyte contained in the polymer solution may be the same as or different from the ionic liquid and electrolyte contained in the electrolyte slurry 15 .

Ionic liquids and electrolytes can be made into ionic liquid electrolytes and added to polymer solutions. At this time, in the ionic liquid electrolyte, the salt concentration of the electrolyte salt per unit volume of the ionic liquid may be 0.3 mol/L or more, 0.5 mol/L or more, or 1.0 mol/L or more, or 3.0 mol/L or more. L or less, 2.7 mol/L or less, or 2.5 mol/L or less.

Based on the total amount of the polymer solution, the content of the ionic liquid electrolyte is preferably at least 3% by mass, more preferably at least 5% by mass, further preferably at least 10% by mass, and more preferably 80% by mass It is less than or equal to, more preferably less than or equal to 75% by mass, further preferably less than or equal to 70% by mass.

The polymer liquid may further contain a dispersion medium. The dispersion medium may be an organic solvent, such as acetone, methyl ethyl ketone, γ-butyrolactone, etc.

In the polymer solution soaking step, the method of making the polymer solution soak in the electrode mixture intermediate layer 14 is, for example, coating the polymer solution on the surface 14a of the electrode mixture intermediate layer 14 on the opposite side to the current collector 13 Methods. Coating may be coating by a coater, coating by spraying, or the like. The polymer solution coated on the electrode mixture intermediate layer 14 is impregnated into the electrode mixture intermediate layer 14 to form an electrode mixture intermediate layer containing a polymer having a structural unit represented by formula (8).

The method of impregnating the polymer solution into the electrode mixture intermediate layer 14 may be, as another method, a method of soaking the current collector 13 formed with the electrode mixture intermediate layer 14 in a polymer solution.

Then, the electrolyte slurry 15 is coated on the surface 14a of the electrode mixture intermediate layer 14 (electrode mixture intermediate layer impregnated with the polymer solution) opposite to the current collector 13 (electrolyte slurry coating step). The composition and coating method of the electrolyte slurry 15 may be the same as those in the above-mentioned embodiment.

In the battery member 19 obtained by the production method having the polymer solution coating step, the polymer represented by the above formula (8) is contained in the electrode mixture layer 18 . Thereby, the ion conductivity of the electrode mixture layer 18 can be improved, and the battery characteristic of the secondary battery obtained using this battery member 19 can be further improved.

The secondary battery provided with the battery member manufactured by the above-mentioned manufacturing method can take various modification examples.

As a first modification, the method for manufacturing a battery member according to each of the above embodiments can also be used as a method for manufacturing a battery member used in a so-called bipolar secondary battery. Fig. 4 is an exploded perspective view showing an embodiment of an electrode group of a secondary battery according to a modified example. The difference between the secondary battery in this modification and the secondary battery in the above-mentioned embodiment is that the electrode group 2B includes bipolar electrodes 21 . That is, as shown in FIG. 4 , electrode group 2B includes positive electrode 6 , first electrolyte layer 7 , bipolar electrode 21 , second electrolyte layer 7 , and negative electrode 8 in this order. The bipolar electrode 22 has: a bipolar electrode current collector 22; a positive electrode mixture layer 10, which is provided on the surface (positive electrode surface) of the negative electrode 8 side of the bipolar electrode current collector 22; and, a negative electrode mixture layer 12, which is provided On the surface (negative electrode surface) of the positive electrode 6 side of the bipolar electrode current collector 22 .

This bipolar secondary battery can be regarded as including a battery member (bipolar electrode member) for a secondary battery including a first electrolyte layer 7, a positive electrode mixture layer 10, a bipolar electrode assembly, and a battery member for a secondary battery. Electrode 22 , negative electrode mixture layer 12 , and second electrolyte layer 7 . A method for manufacturing a battery member according to an embodiment of the present invention is a method for manufacturing such a bipolar electrode member.

A method for manufacturing a bipolar battery member according to an embodiment includes the following steps: a step of forming a positive electrode mixture intermediate layer on one side (one of the main surfaces) of the bipolar current collector 22 (a positive electrode mixture intermediate layer forming step); The step of coating the first electrolyte slurry on the surface of the positive electrode mixture intermediate layer on the side opposite to the bipolar current collector 22 (the first electrolyte slurry coating step); on the other side of the bipolar current collector 22 The step of forming the negative electrode mixture intermediate layer (the negative electrode mixture intermediate layer forming step) on (the other main surface); Step of slurry (second electrolyte slurry coating step). Each step can be implemented using the same materials and methods as the steps in the above embodiments (electrode mixture intermediate layer formation step, electrolyte slurry coating step). Furthermore, the compositions of the first electrolyte slurry and the second electrolyte slurry may be the same composition or different compositions, but are preferably the same composition.

In this embodiment, before the step of coating the electrolyte slurry, a step of soaking a solution containing a polymer into the positive electrode mixture intermediate layer or the negative electrode mixture intermediate layer (polymer solution soaking step) may be further provided, and the polymer has A structural unit represented by the above formula (8). The step of impregnating the polymer solution can be implemented with the same material and method as the step of impregnating the polymer solution in the above embodiment.

After the electrolyte slurry coating step, the positive electrode mixture intermediate layer and the dispersion medium of the first electrolyte slurry are volatilized. Similarly, the negative electrode mixture intermediate layer and the dispersion medium of the second electrolyte slurry were volatilized. The method of volatilizing the dispersion medium may be the same method as in the above-mentioned embodiment. As a result of volatilizing the dispersion medium, a battery member (bipolar electrode member) for a secondary battery can be obtained, which sequentially includes the first electrolyte layer 7, the positive electrode mixture layer 10, the bipolar current collector 22, and the negative electrode mixture layer 12. , and the second electrolyte layer 7.

In a secondary battery obtained using the bipolar electrode member obtained in this manner, the discharge characteristics of the secondary battery can be improved even when discharging is performed at a relatively low current.

As a second modification example, the manufacturing method of the battery member of each of the above-mentioned embodiments may further include the following steps: after forming the electrolyte layer 7, another electrolyte layer (the second electrolyte layer) is laminated on the electrolyte layer (the first electrolyte layer) 7. electrolyte layer). In this case, the first electrolyte layer can well form the interface between the electrode mixture layer and the second electrolyte layer, so the first electrolyte layer can also be called an interface-forming layer. The secondary battery obtained by using the battery member obtained by this production method is sequentially provided with a positive electrode current collector as an electrode group, a positive electrode mixture layer, a first interface forming layer, an electrolyte layer (second electrolyte layer), A second interface forming layer, a negative electrode mixture layer, and a negative electrode current collector.

In one embodiment, it can be considered that the electrode group includes a first battery member (positive electrode member) that includes a positive electrode current collector, a first interface-forming layer, and an electrolyte layer in this order. Similarly, it can also be considered that this electrode group includes a second battery member (negative electrode member) that includes a negative electrode current collector, a negative electrode mixture layer, a second interface forming layer, and an electrolyte layer in this order. The manufacturing method of the second modification is the manufacturing method of the positive electrode member and the negative electrode member.

The interface forming layer may have the same composition as that of the electrolyte layer in the battery members of the above-mentioned embodiments. That is, the manufacturing method of this modified example is a method in which the electrolyte layer is replaced by an interface-forming layer in each of the above-mentioned embodiments.

In this manufacturing method, the battery member can be manufactured by disposing an electrolyte layer on the surface of the positive electrode member on the side of the first interface forming layer or the surface of the negative electrode member on the side of the second interface forming layer. In one embodiment, the electrolyte layer at this time may be formed by forming the above-mentioned electrolyte slurry 15 into a sheet shape. That is, the electrolyte sheet is produced by preparing a substrate such as a thin film made of resin, coating the electrolyte slurry 15 on the substrate, and then volatilizing the dispersion medium. Then, the substrate is peeled off from this electrolyte sheet, whereby an electrolyte layer can be obtained.

In other embodiments, the electrolyte layer in the second variation example may have a different composition from the electrolyte layer made of the electrolyte slurry 15, for example, it may be a known electrolyte such as an organic polymer solid electrolyte or an inorganic solid electrolyte. The composition is formed into a sheet-like electrolyte layer. At this time, the organic polymer solid electrolyte can be polyethylene oxide, etc.; the inorganic solid electrolyte can be Li ₇ La ₃ Zr ₂ O ₁₂ , Li _6.75 La ₃ Zr _1.75 Nb _0.25 O ₁₂ (LLZ-Nb), Li _6.75 La ₃ Zr _1.75 Ta _0.25 O ₁₂ , Li _1+c+d Al _c (Ti, Ge) _2-c Si _d P _3-d O ₁₂ (where 0≦c>2, 0≦d>3. Furthermore , (Ti, Ge) means either Ti or Ge, or both of Ti and Ge), Li ₁₀ GeP ₂ S ₁₂ , Li _9.54 Si _1.74 P _1.44 S _11.7 Cl _0.3 and the like.

In a secondary battery obtained using the battery member obtained in this manner, the discharge characteristics of the secondary battery can be improved even when discharging is performed at a relatively low current. Further, by containing the ionic liquid electrolyte in the interface-forming layer, ion conduction between the interface-forming layer and the electrolyte layer becomes easier. As a result, the secondary battery obtained by using the battery member of this modified example can form an interface between layers well, and therefore has excellent battery characteristics. [Example]

Embodiments of the present invention will be described below. However, the present invention is not limited to the following embodiments. In addition, when expressing the composition of the ionic liquid (ionic liquid electrolytic solution) which melt|dissolved an electrolytic salt below, it may express in the form of "concentration of electrolytic salt/kind of electrolytic salt/kind of ionic liquid".

<Example 1> [Making positive electrode components] 92.5 parts by mass of layered lithium/nickel/manganese/cobalt composite oxide (positive electrode active material), 2.5 parts by mass of acetylene black (conductive agent, product name: HS-100 , the average particle size is 48nm, manufactured by Denka Co., Ltd.), and 5 parts by mass of a copolymer solution of vinylidene fluoride and hexafluoropropylene (solid content is 12 mass%) dispersed in an appropriate amount of dispersion medium, that is, N-formazan Base-2-pyrrolidone (NMP) to prepare positive electrode mixture slurry. Coat the positive electrode mixture slurry on the positive electrode current collector (aluminum foil with a thickness of 20 μm) with a coating amount of 125 g/m ² , and heat it at 80° C. for 12 hours to dry it, and then press it, thereby A positive electrode mixture intermediate layer with a mixture density of 2.7 g/cm ³ was formed. After cutting this into a width of 30 mm and a length of 45 mm, a positive electrode current collector terminal was attached.

Make 25 mass parts of PVDF-HFP, 12 mass parts of SiO ₂ particles (specific surface area: 50m ² /g, surface treatment: hexamethyldisilazane, average primary particle diameter: 40nm, product name: AEROSIL RX50, Japan AEROSIL Co., Ltd.), and 63 parts by mass of an ionic liquid electrolyte (2.0mol/L/Li[FSI]/EMI-FSI) were dispersed in an appropriate amount of dispersion medium, that is, NMP, to prepare an electrolyte slurry. Based on the total non-volatile components of the electrolyte slurry, the content of SiO ₂ particles was 9% by volume, and the content of the ionic liquid electrolyte was 70% by volume. The obtained electrolyte slurry was coated on the surface of the positive electrode mixture intermediate layer opposite to the positive electrode current collector, and heated at 80° C. for 12 hours to volatilize the dispersion medium to form an electrolyte layer. Thereby, a positive electrode member including a positive electrode current collector, a positive electrode mixture layer, and an electrolyte layer in this order is obtained. The thickness of the electrolyte layer in the obtained positive electrode member was 15±2 μm.

[making the negative electrode member] making 92 parts by mass of graphite (negative electrode active material, manufactured by Hitachi Chemical Co., Ltd.), 3 parts by mass of acetylene black (conductive agent, product name: HS-100, average particle diameter is 48nm, Denka Co., Ltd. manufactured by the company), and 5 parts by mass of a copolymer solution of vinylidene fluoride and hexafluoropropylene (solid content is 12 mass%) are dispersed in an appropriate amount of dispersion medium, that is, NMP, to prepare negative electrode mixture slurry. Coat this negative electrode mixture slurry on the current collector (copper foil with a thickness of 10 μm) with a coating amount of 60 g/m ² , and heat it at 80° C. for 12 hours to dry it, and then press it, thereby A negative electrode mixture intermediate layer with a mixture density of 1.8 g/cm ³ was formed. After cutting this into a width of 31 mm and a length of 46 mm, a negative electrode current collector terminal was attached.

The electrolyte layer is formed by applying the electrolyte slurry on the surface of the negative electrode mixture intermediate layer opposite to the negative electrode current collector by the same method as that of the positive electrode member, and then volatilizing the dispersion medium. Thereby, a negative electrode member including a negative electrode current collector, a negative electrode mixture layer, and an electrolyte layer in this order is obtained. The thickness of the electrolyte layer in the obtained negative electrode member was 15±2 μm.

[Production of lithium-ion secondary batteries] An electrode group is produced by laminating the produced positive electrode member and negative electrode member such that the respective electrolyte layers are in contact with each other. As shown in Fig. 1, this electrode group is housed in a battery case made of aluminum laminated films. In this battery case, the above-mentioned positive electrode current collector terminal and negative electrode current collector terminal were taken out to the outside, and the opening of the battery container was sealed to produce a lithium ion secondary battery. In addition, the laminated film made of aluminum is a laminated body of polyethylene terephthalate (PET) film/aluminum foil/sealant layer (polypropylene, etc.). The designed capacity of the produced lithium ion secondary battery was 20 mAh.

<Examples 2 to 22, Reference Examples 1 to 2> Lithium was produced by the same method as in Example 1, except that the composition of the electrolyte slurry was changed as shown in Table 1 for the production of positive electrode members and negative electrode members. ion secondary battery. Furthermore, regarding the oxide particles, the oxide particles in the table with an average primary particle diameter of 40 nm and after surface treatment are the same _SiO2 particles as in Example 1, with an average primary particle diameter of 40 nm and without surface treatment. The particles were AEROSIL OX50 (product name) manufactured by Japan Aerosil Co., Ltd., and the oxide particles with an average primary particle diameter of 7 nm were S5130 (product name) manufactured by SIGMA-ALDRICH.

＜Evaluation of discharge characteristics＞ Implement constant current charging of 0.1C until the upper limit voltage is 4.2V. Then, a constant current discharge with a cut-off voltage of 2.7V was performed at a current value of 0.1C, and the capacity during this discharge was defined as the discharge capacity at a current value of 0.1C. Then, carry out the constant current charge of 0.1C until the upper limit voltage is 4.2V, and carry out the constant current discharge with the termination voltage of 2.7V at the current value of 0.2C, and then set the capacity at the time of discharge as the current value of 0.2C when the discharge capacity. The discharge capacity maintenance ratio (0.2C/0.1C) was calculated according to the following formula. The discharge capacity at 0.5C was also measured in the same manner, and the discharge capacity retention ratio (0.5C/0.1C) was obtained. The results are shown in Table 1. Discharge capacity maintenance rate (%) = (discharge capacity when the current value is 0.2C or 0.5C/discharge capacity when the current value is 0.1C) × 100

[Table 1]

1‧‧‧Secondary battery 2, 2A, 2B‧‧‧electrode group 3‧‧‧Battery case 4‧‧‧Positive collector terminal 5‧‧‧Negative collector terminal 6‧‧‧Positive electrode 7‧‧‧electrolyte layer 8‧‧‧Negative electrode 9‧‧‧Cathode collector 10‧‧‧Positive electrode mixture layer 11‧‧‧Negative electrode collector 12‧‧‧Negative electrode mixture layer 13‧‧‧Collector 13a, 14a‧‧‧face 14‧‧‧Intermediate layer of electrode mixture 15‧‧‧Slurry (electrolyte slurry) 16‧‧‧Oxide particles 17‧‧‧polymer 18‧‧‧Electrode mixture layer 19‧‧‧Battery components for secondary batteries 21‧‧‧bipolar electrode 22‧‧‧Bipolar Current Collector

Fig. 1 is a perspective view showing a secondary battery according to an embodiment. Fig. 2 is an exploded perspective view showing an embodiment of the electrode group of the secondary battery shown in Fig. 1 . Fig. 3 is a schematic cross-sectional view showing a method of manufacturing a battery member for a secondary battery according to an embodiment. Fig. 4 is an exploded perspective view showing an embodiment of an electrode group of a secondary battery according to a modified example.

Domestic deposit information (please note in order of depositor, date, and number) none

Overseas storage information (please note in order of storage country, organization, date, and number) none

7‧‧‧electrolyte layer

13‧‧‧Collector

13a, 14a‧‧‧face

14‧‧‧Intermediate layer of electrode mixture

15‧‧‧Slurry (electrolyte slurry)

16‧‧‧Oxide particles

17‧‧‧polymer

18‧‧‧Electrode mixture layer

19‧‧‧Battery components for secondary batteries

Claims (3)

A method for manufacturing a battery component for a secondary battery, comprising the steps of: forming an electrode mixture intermediate layer containing an electrode active material on one side of a current collector; A step of coating a slurry containing oxide particles, a polymer, an ionic liquid, and an electrolyte salt on the surface opposite to the electrode; The ratio of the content is greater than 4/1 and less than 12/1 in terms of volume ratio, and the concentration of the aforementioned electrolyte salt per unit volume of the aforementioned ionic liquid is greater than 0.5 mol/L and less than 3.0 mol/L. The method for manufacturing a battery member for a secondary battery according to claim 1, wherein the oxide particles have a specific surface area of 2 to 400 m ² /g. The method of manufacturing a battery member for a secondary battery according to claim 1 or 2, wherein the ionic liquid contains N(SO ₂ F) ₂ ^- as an anion component.

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