WO2020017439A1 - Electrolyte sheet production method and secondary battery production method - Google Patents

Abstract

Disclosed is an electrolyte sheet production method comprising the steps of: applying, onto a substrate, an electrolyte slurry composition containing one or more polymers, oxide particles, at least one electrolyte salt selected from the group consisting of a lithium salt, a sodium salt, a calcium salt, and a magnesium salt, a compound represented by General Formula (10) and/or an ionic liquid, and a dispersion medium; and removing the dispersion medium from the electrolyte slurry composition coating, thereby forming an electrolyte layer on the substrate. The substrate has a contact angle with the dispersion medium of 60º or less. (10) R^AO-(CH₂CH₂O)_y-R^B [In the formula (10), R^A and R^B independently represent a C_1-4 alkyl group and y represents an integer of 1 to 6.]

Description

Method for producing electrolyte sheet and method for producing secondary battery

The present invention relates to a method for manufacturing an electrolyte sheet and a method for manufacturing a secondary battery.

In recent years, with the spread of portable electronic devices, electric vehicles, and the like, high-performance secondary batteries are required. Among them, lithium secondary batteries have a high energy density, and thus have attracted attention as power sources for batteries for electric vehicles, batteries for power storage, and the like. Specifically, lithium secondary batteries as batteries for electric vehicles include zero-emission electric vehicles without engines, hybrid electric vehicles with both engines and secondary batteries, and plug-in hybrids that charge directly from the power system. Used in electric vehicles such as electric vehicles. A lithium secondary battery as a power storage battery is used in a stationary power storage system or the like that supplies power stored in advance in an emergency when a power system is cut off.

リ チ ウ ム There is a need for a lithium secondary battery with a higher energy density for use in such a wide range of applications, and its development is underway. In particular, lithium secondary batteries for electric vehicles are required to have high safety in addition to high input / output characteristics and high energy density. Therefore, more advanced technology for ensuring safety is required. Conventionally, as a method of improving the safety of a lithium secondary battery, a method of gelling a component used in an electrolytic solution to form a gel electrolyte is known (for example, see Patent Documents 1 and 2).

JP 2000-164254 A JP 2007-141467 A

By the way, when preparing an electrolyte sheet including a base material and an electrolyte layer provided on the base material, an electrolyte slurry composition containing an electrolyte component and a dispersion medium was applied on the base material, and the coating was performed. Generally, an electrolyte layer is formed on a substrate by removing a dispersion medium from an electrolyte slurry composition. In order to stably supply the electrolyte sheet, it is important that the electrolyte layer does not change significantly in the coating and drying step. In particular, in the production of an electrolyte sheet, it is required that the coating width when the electrolyte slurry composition is applied does not fluctuate significantly even after the dispersion medium is removed.

Accordingly, it is a main object of the present invention to provide a method for manufacturing an electrolyte sheet in which a coating width when coating an electrolyte slurry composition is not easily changed even after removing a dispersion medium.

The first aspect of the present invention provides one or more polymers, oxide particles, and at least one electrolyte salt selected from the group consisting of lithium salts, sodium salts, calcium salts, and magnesium salts, A step of applying an electrolyte slurry composition containing at least one of the compound represented by the following general formula (10) and an ionic liquid, and a dispersion medium onto a substrate, and dispersing the electrolyte slurry composition from the applied electrolyte slurry composition. Removing the medium to form an electrolyte layer on the base material, wherein the contact angle of the base material with the dispersion medium is 60 ° or less.
R ^A O- (CH ₂ CH ₂ O) _y -R ^B (10)
[In the formula (10), R ^A and R ^B each independently represent an alkyl group having 1 to 4 carbon atoms, and y represents an integer of 1 to 6. ]

(4) When the contact angle with the dispersion medium is 60 ° or less, the base material tends to have excellent adhesion to other members (for example, an adhesive tape or the like). Therefore, it is presumed that the use of such a base material provides excellent adhesion between the base material and the electrolyte layer provided on the base material.

The contact angle is preferably 40 ° or less.

The oxide particles are preferably at least one selected from the group consisting of SiO ₂ , Al ₂ O ₃ , AlOOH, MgO, CaO, ZrO ₂ , TiO ₂ , Li ₇ La ₃ Zr ₂ O ₁₂ , and BaTiO ₃ . Particles.

The ionic liquid preferably contains, as the cation component, at least one selected from the group consisting of a chain quaternary onium cation, a piperidinium cation, a pyrrolidinium cation, a pyridinium cation, and an imidazolium cation.

The ionic liquid preferably contains at least one anion component represented by the following general formula (A) as the anion component.
_{N (SO 2 C m F 2m} + 1) (SO 2 C n F 2n + 1) - (A)
[In the formula (A), m and n each independently represent an integer of 0 to 5. ]

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

Preferably, the polymer has a first structural unit and a second structural unit selected from the group consisting of hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate, and methyl methacrylate, among the structural units constituting the polymer. Is included.

The electrolyte salt is preferably an imide-based lithium salt.

化合物 The compound represented by the general formula (10) preferably contains tetraethylene glycol dimethyl ether.

The second aspect of the present invention includes a step of forming a positive electrode mixture layer on a positive electrode current collector to obtain a positive electrode, a step of forming a negative electrode mixture layer on a negative electrode current collector to obtain a negative electrode, Disposing the electrolyte layer of the electrolyte sheet obtained by the method of (1) between the positive electrode and the negative electrode.

According to the present invention, there is provided a method for producing an electrolyte sheet, in which a coating width when applying an electrolyte slurry composition is not easily changed even after removing a dispersion medium. It is presumed that the electrolyte sheet manufactured by such a manufacturing method is excellent also in the point of adhesion between the electrolyte layer and the substrate. Further, according to the present invention, there is provided a method for manufacturing a secondary battery using the electrolyte sheet obtained by such a manufacturing method.

FIG. 1 is a perspective view illustrating a secondary battery according to a first embodiment. FIG. 2 is an exploded perspective view illustrating an embodiment of an electrode group in the secondary battery illustrated in FIG. 1. FIG. 2 is a schematic cross-sectional view illustrating one embodiment of an electrode group in the secondary battery illustrated in FIG. 1. (A) is a schematic sectional view showing an electrolyte sheet according to one embodiment, and (b) is a schematic sectional view showing an electrolyte sheet according to another embodiment. It is a schematic cross section showing one embodiment of an electrode group in a secondary battery concerning a 2nd embodiment.

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

数 値 The numerical values and ranges in this specification do not limit the present invention. In the present specification, a numerical range indicated by using “to” indicates a range including numerical values described before and after “to” as a minimum value and a maximum value, respectively. In the numerical ranges described in stages in this specification, the upper limit or the lower limit described in one numerical range may be replaced with the upper limit or the lower limit described in another step. In the numerical ranges described in this specification, the upper limit or the lower limit of the numerical range may be replaced with the value shown in the embodiment.

[First Embodiment]
FIG. 1 is a perspective view showing the secondary battery according to the first embodiment. As shown in FIG. 1, the secondary battery 1 includes an electrode group 2 including a positive electrode, a negative electrode, and an electrolyte layer, and a bag-shaped battery case 3 containing the electrode group 2. The positive electrode and the negative electrode are provided with a positive electrode current collecting tab 4 and a negative electrode current collecting tab 5, respectively. The positive electrode current collecting tab 4 and the negative electrode current collecting tab 5 protrude from inside the battery exterior body 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 respectively.

The battery casing 3 may be formed of, for example, a laminate film. The laminated film may be, for example, a laminated film in which a resin film such as a polyethylene terephthalate (PET) film, a metal foil such as aluminum, copper, and stainless steel, and a sealant layer such as polypropylene are laminated in this order.

FIG. 2 is an exploded perspective view showing one embodiment of the electrode group 2 in the secondary battery 1 shown in FIG. FIG. 3 is a schematic sectional view showing one embodiment of the electrode group 2 in the secondary battery 1 shown in FIG. As shown in FIGS. 2 and 3, the electrode group 2A according to the present embodiment 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. The positive electrode current collector 9 is provided with a positive electrode current collector tab 4. 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. The negative electrode current collector 11 is provided with a negative electrode current collection tab 5.

The positive electrode current collector 9 may be formed of aluminum, stainless steel, titanium, or the like. Specifically, the positive electrode current collector 9 may be, for example, an aluminum perforated foil having a hole diameter of 0.1 to 10 mm, an expanded metal, a foamed metal plate, or the like. In addition to the above, the positive electrode current collector 9 may be formed of any material as long as it does not cause a change such as dissolution and oxidation during use of the battery, and may be formed of any material. Not restricted.

The thickness of the positive electrode current collector 9 may be 10 μm or more and 100 μm or less, and is preferably 10 μm or more and 50 μm or less from the viewpoint of reducing the volume of the entire positive electrode. From the viewpoint of rotation, it is more preferably 10 μm or more and 20 μm or less.

(4) In one embodiment, the positive electrode mixture layer 10 contains a positive electrode active material, a conductive agent, and a binder.

(4) The positive electrode active material may be a lithium transition metal compound such as a lithium transition metal oxide and a lithium transition metal phosphate.

The lithium transition metal oxide may be, for example, lithium manganate, lithium nickelate, lithium cobaltate, or the like. Lithium transition metal oxide, a part of transition metal such as Mn, Ni, Co contained in lithium manganate, lithium nickelate, lithium cobaltate or the like, one or more other transition metals, or A lithium transition metal oxide substituted with a metal element (typical element) such as Mg or Al may be used. That is, the lithium transition metal oxide may be a compound represented by ^LiM 1 _{O 2} or ^{LiM ₁} 2 _O 4 ^(M ₁ comprises 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 or the like.

The lithium transition metal oxide is preferably a compound represented by the following formula (1) from the viewpoint of further improving the energy density.
^{_{Li a Ni b Co c M 2}} d O 2 + e (1)
[In the 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 each represent 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 a number satisfying b + c + d = 1 It is. ]

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

(4) The positive electrode active material may be non-granulated primary particles or granulated secondary particles.

粒径 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 the positive electrode active material contains coarse particles having a particle size greater than the thickness of the positive electrode mixture layer 10, the coarse particles are removed in advance by sieving, airflow classification, or the like, and the particles having a thickness equal to or less than the thickness of the positive electrode mixture layer 10 are removed. A positive electrode active material having a diameter is selected.

(4) The average particle diameter of the positive electrode active material is preferably 0.1 μm or more, more preferably 1 μm or more. Further, it 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 (D50) when the ratio (volume fraction) to the volume of the entire positive electrode active material is 50%. The average particle diameter (D50) of the positive electrode active material is obtained by measuring a suspension of the positive electrode active material in water by a laser scattering method using a laser scattering type particle size measuring device (for example, Microtrack). Is obtained.

含有 The content of the positive electrode active material may be 70% by mass or more, 80% by mass or more, or 85% by mass or more based on the total amount of the positive electrode mixture layer. The content of the positive electrode active material may be 95% by mass or less, 92% by mass or less, or 90% by mass or less based on the total amount of the positive electrode mixture layer.

The conductive agent is not particularly limited, and may be a carbon material such as graphite, acetylene black, carbon black, carbon fiber, carbon nanotube, or the like. The conductive agent may be a mixture of two or more of the above-described carbon materials.

含有 The content of the conductive agent may be 0.1% by mass or more, 1% by mass or more, or 3% by mass or more based on the total amount of the positive electrode mixture layer. The content of the conductive agent is preferably 15% by mass or less, more preferably not more than 15% by mass, based on the total amount of the positive electrode mixture layer, from the viewpoint of suppressing an increase in the volume of the positive electrode 6 and a decrease in the energy density of the secondary battery 1 accompanying the increase. It is at most 10% by mass, more preferably at most 8% by mass.

The binder is not limited as long as it does not decompose on the surface of the positive electrode 6, but is selected from the group consisting of ethylene tetrafluoride, vinylidene fluoride, hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate, and methyl methacrylate. Or a rubber such as styrene-butadiene rubber, isoprene rubber, acrylic rubber or the like containing at least one of the above as monomer units. The binder is preferably a copolymer containing ethylene tetrafluoride and vinylidene fluoride as structural units.

含有 The content of the binder may be 0.5% by mass or more, 1% by mass or more, or 3% by mass or more based on the total amount of the positive electrode mixture layer. The content of the binder may be 20% by mass or less, 15% by mass or less, or 10% by mass or less based on the total amount of the positive electrode mixture layer.

The positive electrode mixture layer 10 may further contain an ionic liquid.

イ オ ン As the ionic liquid, an ionic liquid used in an electrolyte slurry composition described later can be used. The content of the ionic liquid contained in the positive electrode mixture layer 10 is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more, based on the total amount of the positive electrode mixture layer. The content of the ionic liquid contained in the positive electrode mixture layer 10 is preferably 30% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass or less, based on the total amount of the positive electrode mixture layer.

イ オ ン The ionic liquid contained in the positive electrode mixture layer 10 may have an electrolyte salt dissolved therein. As the electrolyte salt, an electrolyte salt used in an electrolyte slurry composition described later can be used.

From the viewpoint of further improving the conductivity, the thickness of the positive electrode mixture layer 10 is a thickness equal to or more than the average particle diameter of the positive electrode active material, specifically, 10 μm or more, 15 μm or more, or 20 μm or more. Good. The thickness of the positive electrode mixture layer 10 may be 100 μm or less, 80 μm or less, or 70 μm or less. By setting the thickness of the positive electrode mixture layer to 100 μm or less, the unevenness of charge and discharge due to the variation in the charge level of the positive electrode active material near the surface of the positive electrode mixture layer 10 and the surface of the positive electrode current collector 9 is suppressed. it can.

The negative electrode current collector 11 may be a metal such as aluminum, copper, nickel, and stainless steel, or an alloy thereof. The negative electrode current collector 11 is preferably aluminum and its alloy because it is lightweight and has a high weight energy density. The negative electrode current collector 11 is preferably made of copper from the viewpoint of ease of processing into a thin film and cost.

The thickness of the negative electrode current collector 11 may be 10 μm or more and 100 μm or less, and is preferably 10 μm or more and 50 μm or less from the viewpoint of reducing the volume of the entire negative electrode, and the negative electrode is wound with a small curvature when forming a battery. From the viewpoint of rotation, it is more preferably 10 μm or more and 20 μm or less.

In one embodiment, the negative electrode mixture layer 12 contains a negative electrode active material and a binder.

As the negative electrode active material, those commonly used in the field of energy devices can be used. Specific examples of the negative electrode active material include lithium metal, lithium titanate (Li ₄ Ti ₅ O ₁₂ ), a lithium alloy or other metal compounds, a carbon material, a metal complex, and an organic polymer compound. . The negative electrode active material may be one of these alone or a mixture of two or more thereof. Examples of the carbon material include natural graphite (flaky graphite, etc.), graphite such as artificial graphite (graphite), amorphous carbon, carbon fiber, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black. And the like. From the viewpoint of obtaining a larger theoretical capacity (for example, 500 to 1500 Ah / kg), the negative electrode active material may be silicon, tin, or a compound containing these elements (oxide, nitride, alloy with another metal). Good.

The average particle size (D ₅₀ ) of the negative electrode active material is preferably 1 μm or more from the viewpoint of obtaining a well-balanced negative electrode having an increased irreversible capacity with a decrease in particle size and an increased ability to retain an electrolyte salt. And more preferably 5 μm or more, further preferably 10 μm or more, and preferably 50 μm or less, more preferably 40 μm or less, and still more preferably 30 μm or less. The average particle size of the negative electrode active material (D ₅₀₎ is measured in the same manner as the average particle diameter of the above-mentioned positive electrode active material (D _50).

含有 The content of the negative electrode active material may be 60% by mass or more, 65% by mass or more, or 70% by mass or more based on the total amount of the negative electrode mixture layer. The content of the negative electrode active material may be 99% by mass or less, 95% by mass or less, or 90% by mass or less based on the total amount of the negative electrode mixture layer.

The binder and the content thereof may be the same as the binder and the content thereof in the positive electrode mixture layer 10 described above.

The negative electrode mixture layer 12 may further contain a conductive agent from the viewpoint of further lowering the resistance of the negative electrode 8. The conductive agent and the content thereof may be the same as the conductive agent and the content thereof in the positive electrode mixture layer 10 described above.

The negative electrode mixture layer 12 may further contain an ionic liquid.

イ オ ン As the ionic liquid, an ionic liquid used in an electrolyte slurry composition described later can be used. The content of the ionic liquid contained in the negative electrode mixture layer 12 is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more, based on the total amount of the negative electrode mixture layer. The content of the ionic liquid contained in the negative electrode mixture layer 12 is preferably 30% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass or less, based on the total amount of the negative electrode mixture layer.

イ オ ン The ionic liquid contained in the negative electrode mixture layer 12 may contain an electrolyte salt similar to the electrolyte salt that can be used for the positive electrode mixture layer 10 described above.

The thickness of the negative electrode mixture layer 12 may be 10 μm or more, 15 μm or more, or 20 μm or more. The thickness of the negative electrode mixture layer 12 may be 100 μm or less, 80 μm or less, or 70 μm or less.

The electrolyte layer 7 is formed by preparing an electrolyte sheet on a base material using an electrolyte slurry composition. The electrolyte slurry composition comprises one or more polymers, oxide particles, at least one electrolyte salt selected from the group consisting of lithium salts, sodium salts, calcium salts, and magnesium salts; It contains at least one of the compound (glyme) represented by (10) and an ionic liquid, and a dispersion medium. Here, the contact angle of the substrate with the dispersion medium is 60 ° or less.

The electrolyte slurry composition contains one or more polymers. The polymer preferably has a first structural unit selected from the group consisting of ethylene tetrafluoride and vinylidene fluoride.

The structural unit constituting the polymer includes the first structural unit and a second structural unit selected from the group consisting of hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate, and methyl methacrylate. May be. That is, the first structural unit and the second structural unit may be included in one kind of polymer to constitute a copolymer, and the first structural unit and the second structural unit may be included in different polymers and have the first structural unit having the first structural unit. And a second polymer having a second structural unit may be at least two types of polymers.

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

The content of the polymer is preferably 3% by mass or more based on the total amount of the components excluding the dispersion medium of the electrolyte slurry composition. The content of the polymer is preferably 50% by mass or less, more preferably 40% by mass or less, based on the total amount of the components excluding the dispersion medium of the electrolyte slurry composition. The content of the polymer is preferably 3 to 50% by mass, more preferably 3 to 40% by mass, based on the total amount of the components excluding the dispersion medium of the electrolyte slurry composition.

ポ リ Since the polymer according to the present embodiment has excellent affinity for the ionic liquid contained in the electrolyte slurry composition, it retains glyme or the electrolyte in the ionic liquid when the electrolyte layer 7 is formed. Thus, leakage of glyme or ionic liquid when a load is applied to the electrolyte layer 7 is suppressed.

The electrolyte slurry composition contains oxide particles. The oxide particles are, for example, particles of an inorganic oxide. The inorganic oxide is, for example, an inorganic oxide containing Li, Mg, Al, Si, Ca, Ti, Zr, La, Na, K, Ba, Sr, V, Nb, B, Ge, or the like as a constituent element. Good. The oxide particles are preferably at least one selected from the group consisting of SiO ₂ , Al ₂ O ₃ , AlOOH, MgO, CaO, ZrO ₂ , TiO ₂ , Li ₇ La ₃ Zr ₂ O ₁₂ , and BaTiO ₃ . Particles. Since the oxide particles have polarity, the dissociation of the electrolyte in the electrolyte layer 7 can be promoted, and the battery characteristics can be improved.

Judging from the apparent geometrical form, oxide particles generally include a primary particle (a particle that does not constitute a secondary particle) that integrally forms a single particle, and a plurality of primary particles. And secondary particles formed by assembling.

The specific surface area of the oxide ^{particles, 2 ~ 380m 2 / g,} 5 ~ 100m 2 / g, 10 ~ 80m 2 / g, or from 15 ~ ^60m 2 / g. When the specific surface area is from 2 to 380 m ² / g, the discharge characteristics of the secondary battery tend to be more excellent. From the same viewpoint, the specific surface area of the oxide particles may be 5 m ² / g or more, 10 m ² / g or more, or 15 m ² / g or more, and 100 m ² / g or less, 80 m ² / g or less, or It may be 60 m ² / g or less. The specific surface area of the oxide particles means the specific surface area of the entire oxide particles including the primary particles and the secondary particles, and is measured by a BET method.

The average primary particle size of the oxide particles (average particle size of the primary particles) is preferably 0.005 μm (5 nm) or more, more preferably 0.01 μm (10 nm) or more, and still more preferably from the viewpoint of further improving the conductivity. Is 0.015 μm (15 nm) or more. The average primary particle size of the oxide particles is preferably 1 μm or less, more preferably 0.1 μm or less, and still more preferably 0.05 μm or less, from the viewpoint of making the electrolyte layer 7 thin. The average primary particle size of the oxide particles is preferably from 0.005 to 1 μm, from 0.01 to 0.01 from the viewpoint of reducing the thickness of the electrolyte layer 7 and suppressing the protrusion of the oxide particles from the surface of the electrolyte layer 7. It is 0.1 μm, or 0.015 to 0.05 μm. The average primary particle size of the oxide particles can be measured by observing the oxide particles with a transmission electron microscope or the like.

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

The shape of the oxide particles may be, for example, lump or substantially spherical. The aspect ratio of the oxide particles is preferably 10 or less, more preferably 5 or less, and still more preferably 2 or less, from the viewpoint of facilitating the thinning of the electrolyte layer 7. The aspect ratio was calculated from the scanning electron micrograph of the oxide particles, the length of the particles in the major axis direction (maximum length of the particles) and the length of the particles in the minor axis direction (minimum length of the particles). Is defined as the ratio of The length of the particles can be obtained by statistically calculating the photograph using a commercially available image processing software (for example, image analysis software A-kun (registered trademark) manufactured by Asahi Kasei Engineering Corporation).

The oxide particles may be surface-treated with a surface treatment agent. Examples of the surface treatment agent include a silicon-containing compound. Silicon-containing compounds include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxydiphenylsilane, n-propyltrimethoxysilane, hexyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyl Alkoxysilanes such as diethoxysilane and n-propyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, Epoxy group-containing silanes such as 3-glycidoxypropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane; N-2- (aminoethyl) -3-aminopropylmethyldisilane Amino group-containing silanes such as toxoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, hexamethyldisilazane, etc. And siloxanes such as dimethyl silicone oil.

酸化 物 As the oxide particles surface-treated with the surface treatment agent, those produced by a known method may be used, or a commercially available product may be used as it is.

The content of the oxide particles is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and particularly preferably, based on the total amount of the components excluding the dispersion medium of the electrolyte slurry composition. It is 20% by mass or more, preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less.

The electrolyte slurry composition contains an electrolyte salt. The electrolyte salt is at least one selected from the group consisting of a lithium salt, a sodium salt, a calcium salt, and a magnesium salt. The electrolyte salt is a compound used to transfer cations between the positive electrode 6 and the negative electrode 8. The above-mentioned electrolyte salt is preferable in that it has a low degree of dissociation at a low temperature, easily diffuses in glyme or ionic liquid, and does not thermally decompose at a high temperature. The electrolyte salt may be an electrolyte salt used in a fluorine ion battery.

The anion components of the electrolyte salt include 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 ^{— and the} like. The anion component of the electrolyte salt is preferably an anion represented by the formula (A) exemplified by an anion component of an ionic liquid described below, such as N (SO ₂ F) ₂ ⁻ and N (SO ₂ CF ₃ ) ₂ ^−. Component PF ₆ ⁻ , BF ₄ ⁻ , B (O ₂ C ₂ O ₂ ) ₂ ⁻ , or ClO ₄ ⁻ .

In the following, the following abbreviations may be used.
[FSI] ⁻ : N (SO ₂ F) ₂ ⁻ , bis (fluorosulfonyl) imide anion [TFSI] ⁻ : N (SO ₂ CF ₃ ) ₂ ⁻ , bis (trifluoromethanesulfonyl) imide anion [BOB] ⁻ : B (O ₂ C ₂ O ₂ ) ₂ ⁻ , bisoxalate borate anion [f3C] ⁻ : C (SO ₂ F) ₃ ⁻ , tris (fluorosulfonyl) carbanion

Lithium salts include 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 , CF ₃ SO ₂ OLi, CF ₃ COOLi, and R′COOLi (R ′ have 1 to 4 carbon atoms) Or an alkyl group, a phenyl group, or a naphthyl group.).

Sodium _{salt, 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 , CF ₃ SO ₂ ONa, CF ₃ COONa, and R′COONa (R ′ has 1 to 4 carbon atoms) Or an alkyl group, a phenyl group, or a naphthyl group.).

Calcium salts include 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 , (CF ₃ SO ₂ O) ₂ Ca, (CF ₃ COO) ₂ Ca, and (R′COO) ₂ Ca (R ′ is an alkyl having 1 to 4 carbon atoms) Or a phenyl group or a naphthyl group).

Magnesium salts include Mg (PF ₆ ) ₂ , Mg (BF ₄ ) ₂ , Mg [FSI] ₂ , Mg [TFSI] ₂ , Mg [f3C] ₂ , Mg [BOB] ₂ , Na (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 , (CF ₃ SO ₃ ) ₂ Mg, (CF ₃ COO) ₂ Mg, and (R′COO) ₂ Mg (R ′ is an alkyl group having 1 to 4 carbon atoms) , A phenyl group, or a naphthyl group.).

The electrolyte salt is preferably one kind selected from the group consisting of an imide-based lithium salt, an imide-based sodium salt, an imide-based calcium salt, and an imide-based magnesium salt, and more preferably an imide-based lithium salt.

The imide-based lithium salt may be Li [TFSI], Li [FSI], or the like. The imide-based sodium salt may be Na [TFSI], Na [FSI] or the like. The imide-based calcium salt may be Ca [TFSI] ₂ , Ca [FSI] ₂ or the like. The imide-based magnesium salt may be Mg [TFSI] ₂ , Mg [FSI] ₂ or the like.

The electrolyte slurry composition contains at least one of the compound (glyme) represented by the general formula (10) and an ionic liquid. Grimes and ionic liquids are not included in the dispersion medium. It is preferable that the electrolyte slurry composition contains an ionic liquid from the viewpoint of discharge characteristics.

Grime is a compound represented by the general formula (10).
R ^A O- (CH ₂ CH ₂ O) _y -R ^B (10)

In the formula (10), R ^A and R ^B each independently represent an alkyl group having 1 to 4 carbon atoms, and y represents an integer of 1 to 6. The alkyl group as R ^A and R ^B may be a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, or the like. Among these, the alkyl group is preferably a methyl group or an ethyl group.

Examples of glymes include triethylene glycol dimethyl ether (sometimes referred to as “triglyme” or “G3”), tetraethylene glycol dimethyl ether (sometimes referred to as “tetraglyme” or “G4”), and pentaethylene glycol dimethyl ether (“pentane”). Glyme "or" G5 "), hexaethylene glycol dimethyl ether (sometimes referred to as" hexaglyme "or" G6 "), and the like. These may be used alone or in combination of two or more. Among these, glyme is preferably triglyme or tetraglyme, more preferably tetraglyme.

When the electrolyte slurry composition contains glyme, part or all of the glyme may form a complex with the electrolyte salt. The complex formed between glyme and the electrolyte salt can have properties similar to the ionic liquid.

The ionic liquid contains the following anion component and cation component. The ionic liquid in the present embodiment is a substance that is liquid at −20 ° C. or higher. It is known that ionic liquids have almost no vapor pressure unlike molecular liquids such as water and a dispersion medium due to strong electrostatic interaction acting between constituent cations and anions.

The anionic component of the ionic liquid is not particularly limited, but anions of halogens such as Cl ⁻ , Br ⁻ , and I ⁻ , inorganic anions such as BF ₄ ⁻ and N (SO ₂ F) ₂ ^— , and 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 the like.

The anionic component of the ionic liquid preferably contains at least one anionic component represented by the following general formula (A).
_{N (SO 2 C m F 2m} + 1) (SO 2 C n F 2n + 1) - (A)

中 In the formula (A), m and n each independently represent an integer of 0 to 5. m and n may be the same or different from each other, and are preferably the same as each other.

The anion component represented by the formula (A) includes, 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 ^— .

The anionic component of the ionic liquid is more preferably N (SO ₂ C ₄ F ₉ ) ₂ ⁻ , CF ₃ SO from the viewpoint of further improving the ionic conductivity at a relatively low viscosity and further improving the charge / discharge characteristics. _At least one selected from the group consisting of ₂ O ⁻ , N (SO ₂ F) ₂ ⁻ , N (SO ₂ CF ₃ ) ₂ ⁻ , and N (SO ₂ C ₂ F ₅ ) ₂ ^−, and more preferably N _{(SO 2 F)} 2 ^- containing.

The cation component of the ionic liquid is not particularly limited, but is preferably at least one selected from the group consisting of a chain quaternary onium cation, a piperidinium cation, a pyrrolidinium cation, a pyridinium cation, and an imidazolium cation.

The chain quaternary onium cation is, for example, a compound represented by the following general formula (2).

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

The piperidinium cation is, for example, a nitrogen-containing six-membered cyclic compound represented by the following general formula (3).

[In the formula (3), R ⁵ and R ⁶ are each independently an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group represented by RO— (CH ₂ ) _n — (R is methyl And n represents an integer of 1 to 4). The alkyl group represented by R ⁵ and R ⁶ preferably has 1 to 20, more preferably 1 to 10, and still more preferably 1 to 5 carbon atoms. ]

The pyrrolidinium cation is, for example, a five-membered cyclic compound represented by the following general formula (4).

[In the formula (4), R ⁷ and R ⁸ are each independently an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group represented by RO— (CH ₂ ) _n — (R is methyl And n represents an integer of 1 to 4). The alkyl group represented by R ⁷ and R ⁸ preferably has 1 to 20, more preferably 1 to 10, and still more preferably 1 to 5 carbon atoms. ]

The pyridinium cation is, for example, a compound represented by the general formula (5).

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

The imidazolium cation is, for example, a compound represented by the general formula (6).

[In the formula (6), 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 is a methyl group Or an ethyl group, and n represents an integer of 1 to 4), or a hydrogen atom. The carbon number of the alkyl group represented by R ¹⁴ to R ¹⁸ is preferably 1 to 20, more preferably 1 to 10, and still more preferably 1 to 5. ]

From the viewpoint of suitably preparing the electrolyte layer 7, the total content of glyme and ionic liquid may be 10% by mass or more and 80% by mass or more based on the total amount of components excluding the dispersion medium of the electrolyte slurry composition. It may be: From the viewpoint of enabling the lithium secondary battery to be charged and discharged at a high load rate, the total content of the glyme and the ionic liquid is preferably 20% based on the total amount of the components excluding the dispersion medium of the electrolyte slurry composition. % By mass or more, more preferably 30% by mass or more.

The concentration of the electrolyte salt per unit volume of the total of glyme and ionic liquid in the electrolyte layer 7 is preferably 0.5 mol / L or more, more preferably 0.7 mol / L or more, from the viewpoint of further improving the charge / discharge characteristics. It is more preferably at least 1.0 mol / L, preferably at most 3.0 mol / L, more preferably at most 2.5 mol / L, even more preferably at most 2.3 mol / L.

The electrolyte slurry composition contains a dispersion medium. However, the above-mentioned glymes and ionic liquids are not included in the dispersion medium. The dispersion medium is not particularly restricted but includes, for example, N-methyl-2-pyrrolidone, dimethylacetamide, acetone, ethyl methyl ketone, cyclohexanone, γ-butyrolactone, 2-butanol, dimethylsulfoxide and the like. These may be used alone or in combination of two or more.

The electrolyte slurry composition may contain other components. Other components include, for example, cellulose fiber, resin fiber, glass fiber and the like. The content of the other components may be 0.1 to 20% by mass based on the total amount of the components excluding the dispersion medium of the electrolyte slurry composition.

濃度 The concentration of the components contained in the electrolyte slurry composition may be 5 to 70% by mass based on the total mass of the electrolyte slurry composition.

The electrolyte slurry composition includes at least one electrolyte salt selected from the group consisting of one or more polymers, oxide particles, lithium salts, sodium salts, calcium salts, and magnesium salts, represented by the general formula (10). It can be prepared by mixing and kneading at least one of the compound and the ionic liquid, a dispersion medium, and other components. Mixing and kneading can be performed by appropriately combining ordinary dispersers such as a stirrer, a mill, a three-roll mill, a ball mill, and a bead mill.

The electrolyte sheet used as the electrolyte layer 7 is a step of arranging the above-described electrolyte slurry composition on a substrate, and forming an electrolyte layer on the substrate by removing a dispersion medium from the arranged electrolyte slurry composition. And a manufacturing method comprising the steps of: FIG. 4A is a schematic cross-sectional view illustrating an electrolyte sheet according to one embodiment. As shown in FIG. 4A, the electrolyte sheet 13A has a base material 14 and an electrolyte layer 7 provided on the base material 14. The electrolyte layer 7 can be composed of components obtained by removing the dispersion medium from the electrolyte slurry composition.

(4) The method for disposing the electrolyte slurry composition on the substrate is not particularly limited, and examples thereof include application by a doctor blade method, a dipping method, a spray method and the like.

(4) The method of removing the dispersion medium from the electrolyte slurry composition is not particularly limited, and examples thereof include a method of heating the electrolyte slurry composition to volatilize the dispersion medium. The heating temperature can be set appropriately according to the dispersion medium used.

The base material 14 has a contact angle to the dispersion medium used in the electrolyte slurry composition of 60 ° or less, has heat resistance enough to withstand heating when the dispersion medium is volatilized, and does not swell with the electrolyte slurry composition. Is not limited. The substrate 14 may be a film made of a resin, and more specifically, a resin such as polyethylene terephthalate (PET), polytetrafluoroethylene, polyimide, polyethersulfone, or polyetherketone (a general-purpose engineering plastic). ) May be used. As the base material 14, a commercially available product satisfying the above conditions can be appropriately selected and used.

The contact angle of the base material 14 with respect to the dispersion medium used in the electrolyte slurry composition is less likely to be small even after the dispersion medium is removed in the coating and drying step when the application of the electrolyte slurry composition is performed. , Since the fluctuation of the coating width is unlikely to occur, it is 60 ° or less, 50 ° or less, 45 ° or less, 40 ° or less, 35 ° or less, 30 ° or less, 25 ° or less, 20 ° or less, or 15 ° or less. It may be. When the contact angle with respect to the dispersion medium is 60 ° or less, the base material 14 tends to have excellent adhesion with other members (for example, an adhesive tape or the like). Therefore, it is presumed that the use of such a base material provides excellent adhesion between the base material and the electrolyte layer provided on the base material. The contact angle of the base material 14 with respect to the dispersion medium used in the electrolyte slurry composition is not particularly limited, but the coating width when the electrolyte slurry composition is applied is not likely to be large even after removing the dispersion medium, The coating width may be 1 ° or more, 2 ° or more, 3 ° or more, 4 ° or more, 5 ° or more, 6 ° or more, 7 ° or more, or 8 ° or more because the coating width hardly changes. In the present specification, the contact angle of the substrate 14 with respect to the dispersion medium used in the electrolyte slurry composition can be determined, for example, by the method described in Examples.

The base material 14 may or may not have been subjected to a release treatment with a surface treatment agent such as silicone. However, since the contact angle tends to be smaller, the release treatment with the surface treatment agent is not preferable. It is preferably not applied.

The base material 14 only needs to have a heat-resistant temperature that can withstand the processing temperature for volatilizing the dispersion medium in the process of manufacturing the electrolyte layer. When the base material 14 is formed of a resin, the heat-resistant temperature is a lower temperature among the softening point (the temperature at which plastic deformation starts) or the melting point of the base material 14. The heat-resistant temperature of the substrate 14 is preferably 50 ° C. or higher, more preferably 100 ° C. or higher, and still more preferably 150 ° C. or higher, from the viewpoint of compatibility with the glyme and the ionic liquid used for the electrolyte layer 7. For example, it may be 400 ° C. or lower. If a substrate having the above heat-resistant temperature is used, the above-described dispersion medium can be suitably used.

It is preferable that the thickness of the base material 14 is as thin as possible while maintaining the strength that can withstand the tensile force in the coating device. The thickness of the substrate 14 is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of securing strength when applying the electrolyte slurry composition to the substrate 14 while reducing the volume of the entire electrolyte sheet 13A. It is more preferably at least 25 μm, preferably at most 100 μm, more preferably at most 50 μm, further preferably at most 40 μm.

The electrolyte sheet can be continuously manufactured while being wound up in a roll shape. In this case, the surface of the electrolyte layer 7 contacts the back surface of the substrate 14 and a part of the electrolyte layer 7 sticks to the substrate 14, which may damage the electrolyte layer 7. In order to prevent such a situation, as another embodiment, the electrolyte sheet may be provided with a protective material on the side opposite to the base material 14 of the electrolyte layer 7. FIG. 4B is a schematic cross-sectional view illustrating an electrolyte sheet according to another embodiment. As shown in FIG. 4B, the electrolyte sheet 13B further includes a protective material 15 on the opposite side of the electrolyte layer 7 from the base material 14.

The protective material 15 may be any material that can be easily peeled off from the electrolyte layer 7, and is preferably a non-polar resin film such as polyethylene, polypropylene, and polytetrafluoroethylene. When a nonpolar resin film is used, the electrolyte layer 7 and the protective material 15 do not adhere to each other, and the protective material 15 can be easily peeled off.

The thickness of the protective material 15 is preferably 5 μm or more, more preferably 10 μm, and preferably 100 μm or less, more preferably 50 μm or less, from the viewpoint of securing strength while reducing the volume of the entire electrolyte sheet 13B. And more preferably 30 μm or less.

The heat resistant temperature of the protective material 15 is preferably −30 ° C. or higher, more preferably 0 ° C. or higher, from the viewpoint of suppressing deterioration in a low temperature environment and suppressing softening in a high temperature environment. It is 100 ° C. or lower, more preferably 50 ° C. or lower. When the protective material 15 is provided, the above-mentioned step of volatilizing the dispersion medium is not essential, so that it is not necessary to increase the heat-resistant temperature.

厚 The thickness of the electrolyte layer 7 is preferably 5 µm or more, more preferably 10 µm or more, from the viewpoint of increasing the conductivity and improving the strength. From the viewpoint of suppressing the resistance of the electrolyte layer 7, the thickness of the electrolyte layer 7 is preferably 200 μm or less, more preferably 150 μm or less, further preferably 100 μm or less, and particularly preferably 50 μm or less.

Next, a method for manufacturing the above-described secondary battery 1 will be described. The method for manufacturing the secondary battery 1 according to the present embodiment includes a first step of forming the positive electrode mixture layer 10 on the positive electrode current collector 9 to obtain the positive electrode 6, and a step of forming the negative electrode mixture on the negative electrode current collector 11. A second step of forming the layer 12 to obtain the negative electrode 8 and a third step of disposing the electrolyte layer 7 of the electrolyte sheet obtained by the above-described manufacturing method between the positive electrode 6 and the negative electrode 8 are provided.

In the first step, for example, the positive electrode 6 is obtained by dispersing the material used for the positive electrode mixture layer in a dispersion medium using a kneader, a disperser, or the like to obtain a slurry-type positive electrode mixture. Is applied on the positive electrode current collector 9 by a doctor blade method, a dipping method, a spray method, or the like, and then the dispersion medium is volatilized. After volatilizing the dispersion medium, a compression molding step by a roll press may be provided as necessary. The positive electrode mixture layer 10 may be formed as a positive electrode mixture layer having a multilayer structure by performing the above-described steps from application of the positive electrode mixture to volatilization of the dispersion medium a plurality of times.

分散 The dispersion medium used in the first step may be water, 1-methyl-2-pyrrolidone (hereinafter also referred to as NMP) or the like.

に お い て In the second step, the method of forming the negative electrode mixture layer 12 on the negative electrode current collector 11 may be the same method as in the first step described above.

In the third step, a method of disposing the electrolyte layer 7 between the positive electrode 6 and the negative electrode 8 using the electrolyte sheet 13A includes, for example, peeling the base material 14 from the electrolyte sheet 13A, and removing the positive electrode 6, the electrolyte layer 7, The secondary battery 1 is obtained by laminating the negative electrode 8 with a laminate, for example. At this time, the electrolyte layer 7 is positioned on the side of the positive electrode mixture layer 10 of the positive electrode 6 and on the side of the negative electrode mixture layer 12 of the negative electrode 8, that is, the positive electrode current collector 9, the positive electrode mixture layer 10, and the electrolyte layer 7. , The negative electrode mixture layer 12 and the negative electrode current collector 11 are stacked in this order.

[Second embodiment]
Next, a secondary battery according to a second embodiment will be described. FIG. 5 is a schematic cross-sectional view showing one embodiment of an electrode group in the secondary battery according to the second embodiment. As shown in FIG. 5, the secondary battery in the second embodiment is different from the secondary battery in the first embodiment in that the electrode group 2B includes the bipolar electrode 16. That is, the electrode group 2B includes the positive electrode 6, the first electrolyte layer 7, the bipolar electrode 16, the second electrolyte layer 7, and the negative electrode 8 in this order.

The bipolar electrode 16 includes a bipolar electrode current collector 17, a positive electrode mixture layer 10 provided on a surface (positive electrode surface) of the bipolar electrode current collector 17 on the negative electrode 8 side, and a positive electrode 6 side of the bipolar electrode current collector 17. (A negative electrode surface).

In the bipolar electrode current collector 17, the positive electrode surface may be preferably formed of a material having excellent oxidation resistance, and may be formed of aluminum, stainless steel, titanium, or the like. In the bipolar electrode current collector 17, the negative electrode surface may be formed of a material that does not form an alloy with lithium, and specifically, may be formed of stainless steel, nickel, iron, titanium, or the like. When different metals are used for the positive electrode surface and the negative electrode surface, the bipolar electrode current collector 17 may be a clad material in which different metal foils are laminated. However, in the case of using the negative electrode 8 that operates at a potential that does not form an alloy with lithium, such as lithium titanate, the above-described limitation is removed and the negative electrode surface may be made of the same material as the positive electrode current collector 9. In that case, the bipolar electrode current collector 17 may be a single metal foil. The bipolar electrode current collector 17 as a single metal foil may be a perforated aluminum foil having a hole diameter of 0.1 to 10 mm, an expanded metal, a foamed metal plate, or the like. In addition to the above, the bipolar electrode current collector 17 may be formed of any material as long as it does not cause a change such as dissolution or oxidation during use of the battery. Is not limited.

The thickness of the bipolar electrode current collector 17 may be not less than 10 μm and not more than 100 μm, and is preferably not less than 10 μm and not more than 50 μm from the viewpoint of reducing the volume of the whole positive electrode. From the viewpoint of winding, the thickness is more preferably 10 μm or more and 20 μm or less.

Next, a method for manufacturing the secondary battery according to the second embodiment will be described. The method for manufacturing a secondary battery according to the present embodiment includes a first step of forming a positive electrode mixture layer 10 on a positive electrode current collector 9 to obtain a positive electrode 6, and a negative electrode mixture layer on a negative electrode current collector 11. A second step of forming the negative electrode 8 by forming the negative electrode mixture layer 12, forming the positive electrode mixture layer 10 on one surface of the bipolar electrode current collector 17, and forming the negative electrode mixture layer 12 on the other surface of the bipolar electrode current collector 17. And a fourth step of disposing the electrolyte layer 7 of the electrolyte sheet obtained by the above-described manufacturing method between the positive electrode 6 and the bipolar electrode 16 and between the negative electrode 8 and the bipolar electrode 16. And

The first step and the second step may be the same method as the first step and the second step in the first embodiment.

方法 In the third step, the method of forming the positive electrode mixture layer 10 on one surface of the bipolar electrode current collector 17 may be the same as the first step in the first embodiment. The method for forming the negative electrode mixture layer 12 on the other surface of the bipolar electrode current collector 17 may be the same as the second step in the first embodiment.

The method of arranging the electrolyte layer 7 of the electrolyte sheet obtained by the above-described manufacturing method between the positive electrode 6 and the bipolar electrode 16 in the fourth step, and the method of obtaining the above-mentioned manufacturing method between the negative electrode 8 and the bipolar electrode 16 The method of arranging the electrolyte layer 7 of the obtained electrolyte sheet may be the same method as the third step in the first embodiment.

The present invention will be specifically described below based on examples, but the present invention is not limited thereto.

(Preparation of base material)
The following base materials were prepared.
Base material A (manufactured by Tokyo Film Service Co., Ltd., PET film, release treatment: none)
Substrate B (manufactured by Tokyo Film Service Co., Ltd., polyimide film, release treatment: none)
Substrate C (manufactured by Tokyo Film Service Co., Ltd., non-silicone release PET film heavy release product, release treatment: yes, presence or absence of silicone in release agent: none)
Substrate D (manufactured by Tokyo Film Service Co., Ltd., silicone release PET film heavy release product, release treatment: yes, presence or absence of silicone in release agent: yes)
Base material E (manufactured by Tokyo Film Service Co., Ltd., silicone release PET film light release product, release treatment: yes, presence or absence of silicone in release treatment agent: yes)
Base material F (manufactured by Tokyo Film Service Co., Ltd., non-silicone release PET film light release product, release treatment: yes, presence or absence of silicone in release treatment agent: no)
Base material G (manufactured by Tokyo Film Service Co., Ltd., non-silicone release PET film light release product, release treatment: yes, presence or absence of silicone in release treatment agent: no)

(Measurement of contact angle of substrate to dispersion medium)
For the substrates A to G, the contact angles of the substrates with respect to the dispersion medium were measured. A contact angle meter (trade name: Drop Master300, manufactured by Kyowa Interface Chemical Co., Ltd.) was used for the measurement. The measurement was performed by dropping N-methyl-2-pyrrolidone (NMP) used as a dispersion medium as a probe liquid on a substrate. The measurement conditions were as follows: the temperature was 25 ° C., the appropriate amount of the probe liquid was 1 μL, and the measurement timing was 1000 ms after the lowering of the probe liquid. The number of trials for measurement was set to three, and the average value of the obtained numerical values was determined as the contact angle θ. Table 1 shows the results.

(Evaluation of adhesion between base material and polyester adhesive tape)
The substrates A to G were evaluated for adhesion. The evaluation of adhesion was performed by measuring a peeling force for peeling a polyester (PEs) adhesive tape (No. 31B tape, manufactured by Nitto Denko Corporation) from the substrate. A sample obtained by cutting the base material to a width of 25 mm and a length of 300 mm was bonded to the base material by reciprocating the polyester adhesive tape once with a 2 kg roller. After leaving still at room temperature (25 ° C.) for 30 minutes, it was pulled in the 180 ° direction at 300 mm / min using a tensile tester, and the peeling force was measured. Table 1 shows the results.

[Example 1]
(Preparation of electrolyte slurry composition)
Lithium bis (trifluoromethanesulfonyl) imide (Li [TFSI]) dried under a dry argon atmosphere is used as an electrolyte salt, and the molar concentration of the electrolyte salt in tetraethylene glycol dimethyl ether (G4) is 2.3 mol / L. To prepare a G4 solution of Li [TFSI]. Next, a copolymer of vinylidene fluoride and hexafluoropropylene (PVDF-HFP) as polymers and SiO ₂ particles as oxide particles (product name: AEROSIL OX50, manufactured by Nippon Aerosil Co., Ltd., specific surface area: 50 m ² / g, average primary particle size: about 40 nm), N-methyl-2-pyrrolidone (NMP) as a dispersion medium is added, and a G4 solution of Li [TFSI] is further added and mixed. Thus, a slurry was obtained. At this time, the polymer, the oxide particles, and Li [TFSI]
The mass ratio with respect to the G4 solution of polymer: oxide particles: G4 solution of Li [TFSI] = 34: 23: 43. NMP as a dispersion medium was added to the obtained slurry to adjust the viscosity, thereby obtaining an electrolyte slurry composition A. The concentration of the contained components in the electrolyte slurry composition A was 28% by mass based on the total mass of the electrolyte slurry composition A.

(Preparation of electrolyte sheet)
The electrolyte slurry composition A was applied on the substrate A using an applicator. The coated electrolyte slurry composition A was heated and dried at 100 ° C. for 1 hour to volatilize the dispersion medium and obtain an electrolyte sheet having an electrolyte layer on a substrate.

(Measurement of coating width)
The width of the electrolyte layer (after volatilizing the dispersion medium of the electrolyte slurry composition A) of the electrolyte sheet prepared above was measured, and the width of the electrolyte layer of the electrolyte sheet relative to the coating width (220 mm) of the electrolyte slurry composition A was measured. (The width of the electrolyte layer of the electrolyte sheet / the coating width of the electrolyte slurry composition A) was calculated as a coating width maintenance ratio in percentage. Table 1 shows the results.

(Preparation of positive electrode)
78.5 parts by mass of layered lithium / nickel / manganese / cobalt composite oxide (positive electrode active material), 5 parts by mass of acetylene black (conductive agent, average particle size 48 nm, product name: HS-100, Denka Corporation), 2.5 parts by mass of a copolymer solution of vinylidene fluoride and hexafluoropropylene (binder, solid content: 12% by mass), ionic liquid solution of electrolyte salt (1.5 M / Li [FSI] / [Py13] [FSI]) 14 parts by mass were mixed to prepare a positive electrode mixture slurry. The positive electrode mixture slurry was coated on a current collector (a 20 μm-thick aluminum foil) at a coating amount of 147 g / m ² and dried at 80 ° C. to obtain a positive electrode having a mixture density of 2.9 g / cm ³ . A mixture layer was formed. This was punched out to φ15 mm to obtain a positive electrode.

(Preparation of negative electrode)
78 parts by mass of graphite A (anode active material, manufactured by Hitachi Chemical Co., Ltd.), 2.4 parts by mass of graphite B (manufactured by Nippon Graphite Industries, Ltd.), carbon fiber (conductive agent, product name: VGCF-H, Showa Denko KK) ) 0.6 parts by mass, 5 parts by mass of a copolymer solution of vinylidene fluoride and hexafluoropropylene (binder, solid content: 12% by mass), an ionic liquid in which an electrolyte salt is dissolved (1.5 M / Li [FSI]) / [Py13] [FSI]) to prepare a negative electrode mixture slurry. This negative electrode mixture slurry was coated on a current collector (10 μm thick copper foil) at a coating amount of 68 g / m ² and dried at 80 ° C. to obtain a negative electrode having a mixture density of 1.9 g / cm ³ . A mixture layer was formed. This was punched out to φ16 mm to obtain a negative electrode.

(Preparation of secondary battery)
The obtained electrolyte sheet was punched out to φ16 mm, and the substrate A was peeled off to obtain an electrolyte layer. A secondary battery for evaluation was manufactured using the positive electrode, the electrolyte layer, and the negative electrode. Here, lithium bis (fluorosulfonyl) imide (Li [FSI]) dried under a dry argon atmosphere was used as an electrolyte salt, and N-methyl-N-propylpyrrolidinium bis (fluorosulfonyl) imide ([Py13] [ FSI] to prepare a [Py13] [FSI] solution of Li [FSI] by dissolving the electrolyte salt in a concentration of 1.5 mol / L. A [Py13] [FSI] solution of Li [FSI] is added into a CR2016 type coin cell container, and a positive electrode, an electrolyte layer, and a negative electrode are stacked in this order, and the upper portion of the battery container is placed via an insulating gasket. It closed by caulking and the secondary battery was obtained.

(Measurement of battery discharge rate characteristics)
With respect to the obtained secondary battery, discharge rate characteristics at 25 ° C. were measured using a charge / discharge device (manufactured by Toyo System Co., Ltd.) under the following charge / discharge conditions.
(1) After performing constant current constant voltage (CCCV) charging at a final voltage of 4.2 V and 0.05 C, two cycles of constant current (CC) discharging at 0.05 C to a final voltage of 2.7 V were performed. C means “current value (A) / battery capacity (Ah)”.
(2) Next, a constant current constant voltage (CCCV) charge is performed at a final voltage of 4.2 V and 0.05 C, and then a constant current (CC) discharge is performed at 0.1 C to a final voltage of 2.7 V. went. Further, the constant current (CC) discharge rate was changed to 0.2, 0.3, 0.5, and 1.0 C every cycle, and the discharge rate characteristics were evaluated. Table 1 shows the results.

[Example 2]
An electrolyte sheet and a secondary battery were prepared in the same manner as in Example 1 except that the substrate A was changed to the substrate B, and the same evaluation as in Example 1 was performed. Table 1 shows the results.

[Example 3]
An electrolyte sheet and a secondary battery were prepared in the same manner as in Example 1 except that the substrate A was changed to the substrate C, and the same evaluation as in Example 1 was performed. Table 1 shows the results.

[Example 4]
An electrolyte sheet and a secondary battery were prepared in the same manner as in Example 1 except that the substrate A was changed to the substrate D, and the same evaluation as in Example 1 was performed. Table 1 shows the results.

[Example 5]
Using lithium bis (fluorosulfonyl) imide (Li [FSI]) dried under a dry argon atmosphere as an electrolyte salt, N-methyl-N-propylpyrrolidinium bis (fluorosulfonyl) imide ([Py13] [FSI]) Then, the electrolyte salt was dissolved at a concentration of 1.5 mol / L to prepare a solution of [Py13] [FSI] of Li [FSI]. Next, a copolymer of vinylidene fluoride and hexafluoropropylene (PVDF-HFP) as polymers and SiO ₂ particles as oxide particles (product name: AEROSIL OX50, manufactured by Nippon Aerosil Co., Ltd., specific surface area: 50 m ² / g, average primary particle size: about 40 nm), N-methyl-2-pyrrolidone (NMP) as a dispersion medium is added, and a [Py13] [FSI] solution of Li [FSI] is further added. And mixed to obtain a slurry. At this time, the mass ratio of the polymer, the oxide particles, and the [Py13] [FSI] solution of Li [FSI] is as follows: polymer: oxide particles: [Py13] [FSI] solution of Li [FSI] = 30: 20:50. NMP as a dispersion medium was added to the obtained slurry to adjust the viscosity, thereby obtaining an electrolyte slurry composition B. The concentration of the component contained in the electrolyte slurry composition B was 28% by mass based on the total mass of the electrolyte slurry composition B. An electrolyte sheet and a secondary battery were prepared in the same manner as in Example 1, except that the electrolyte slurry composition A was changed to the electrolyte slurry composition B, and the coating width maintenance ratio was calculated in the same manner as in Example 1. Then, the discharge rate characteristics of the battery were measured. Table 1 shows the results.

[Example 6]
Except that the base material A was changed to the base material B, an electrolyte sheet and a secondary battery were produced in the same manner as in Example 5, and the coating width maintenance ratio was calculated in the same manner as in Example 1, and the The discharge rate characteristics were measured. Table 1 shows the results.

[Example 7]
Except that the base material A was changed to the base material C, an electrolyte sheet and a secondary battery were prepared in the same manner as in Example 5, and the coating width maintenance ratio was calculated in the same manner as in Example 1, and the The discharge rate characteristics were measured. Table 1 shows the results.

Example 8
Except that the base material A was changed to the base material D, an electrolyte sheet and a secondary battery were produced in the same manner as in Example 5, and the coating width maintenance ratio was calculated in the same manner as in Example 1, and the The discharge rate characteristics were measured. Table 1 shows the results.

[Comparative Example 1]
An electrolyte sheet and a secondary battery were produced in the same manner as in Example 1 except that the substrate A was changed to the substrate E, and the coating width maintenance ratio was calculated in the same manner as in Example 1. Table 1 shows the results. In Comparative Example 1, the discharge rate characteristics of the battery were not measured because the coating width was insufficient.

[Comparative Example 2]
An electrolyte sheet and a secondary battery were produced in the same manner as in Example 1 except that the substrate A was changed to the substrate F, and the coating width maintenance ratio was calculated in the same manner as in Example 1. Table 1 shows the results. In Comparative Example 2, the discharge rate characteristics of the battery were not measured because the coating width was insufficient.

[Comparative Example 3]
An electrolyte sheet and a secondary battery were produced in the same manner as in Example 1 except that the substrate A was changed to the substrate G, and the coating width maintenance ratio was calculated in the same manner as in Example 1. Table 1 shows the results. In Comparative Example 3, the discharge rate characteristics of the battery were not measured because the coating width was insufficient.

[Comparative Example 4]
An electrolyte sheet and a secondary battery were prepared in the same manner as in Example 5, except that the substrate A was changed to the substrate E, and the coating width maintenance ratio was calculated in the same manner as in Example 1. Table 1 shows the results. In Comparative Example 4, the discharge rate characteristics of the battery were not measured because the coating width was insufficient.

[Comparative Example 5]
An electrolyte sheet and a secondary battery were prepared in the same manner as in Example 5 except that the substrate A was changed to the substrate F, and the coating width maintenance ratio was calculated in the same manner as in Example 1. Table 1 shows the results. In Comparative Example 5, the discharge rate characteristics of the battery were not measured because the coating width was insufficient.

[Comparative Example 6]
An electrolyte sheet and a secondary battery were produced in the same manner as in Example 5, except that the substrate A was changed to the substrate G, and the coating width maintenance ratio was calculated in the same manner as in Example 1. Table 1 shows the results. In Comparative Example 6, the discharge rate characteristics of the battery were not measured because the coating width was insufficient.

From these results, the manufacturing method of the electrolyte sheet of the present invention is that in the coating and drying step, the coating width when coating the electrolyte slurry composition is not easily changed even after the dispersion medium is removed. confirmed. It is presumed that the electrolyte sheet produced by the method for producing an electrolyte sheet of the present invention is also excellent in the point of adhesion between the electrolyte layer and the substrate.

DESCRIPTION OF SYMBOLS 1 ... Secondary battery, 2, 2A, 2B ... Electrode group, 3 ... Battery exterior body, 4 ... Positive electrode current collection tab, 5 ... Negative electrode current collection tab, 6 ... Positive electrode, 7 ... Electrolyte layer, 8 ... Negative electrode, 9 ... Positive electrode current collector, 10: positive electrode mixture layer, 11: negative electrode current collector, 12: negative electrode mixture layer, 13A, 13B: electrolyte sheet, 14: base material, 15: protective material, 16: bipolar electrode, 17 ... Bipolar electrode current collector.

Claims (10)

1. One or more polymers, oxide particles, at least one electrolyte salt selected from the group consisting of lithium salts, sodium salts, calcium salts, and magnesium salts, represented by the following general formula (10) Applying an electrolyte slurry composition containing at least one of a compound and an ionic liquid, and a dispersion medium, to a substrate,
   Removing the dispersion medium from the applied electrolyte slurry composition to form an electrolyte layer on the substrate,
   With
   A method for producing an electrolyte sheet, wherein a contact angle of the substrate with the dispersion medium is 60 ° or less.
   R ^A O- (CH ₂ CH ₂ O) _y -R ^B (10)
   [In the formula (10), R ^A and R ^B each independently represent an alkyl group having 1 to 4 carbon atoms, and y represents an integer of 1 to 6. ]
2. 方法 The method for producing an electrolyte sheet according to claim 1, wherein the contact angle is 40 ° or less.
3. The oxide particles are at least one particle selected from the group consisting of SiO ₂ , Al ₂ O ₃ , AlOOH, MgO, CaO, ZrO ₂ , TiO ₂ , Li ₇ La ₃ Zr ₂ O ₁₂ , and BaTiO _3. The method for producing an electrolyte sheet according to claim 1.
4. 4. The ionic liquid according to claim 1, wherein the cation component contains at least one selected from the group consisting of a chain quaternary onium cation, a piperidinium cation, a pyrrolidinium cation, a pyridinium cation, and an imidazolium cation. The method for producing an electrolyte sheet according to any one of the above.
5. The method for producing an electrolyte sheet according to any one of claims 1 to 4, wherein the ionic liquid includes at least one anion component represented by the following general formula (A) as an anion component.
   _{N (SO 2 C m F 2m} + 1) (SO 2 C n F 2n + 1) - (A)
   [In the formula (A), m and n each independently represent an integer of 0 to 5. ]
6. The method for producing an electrolyte sheet according to any one of claims 1 to 5, wherein the polymer has a first structural unit selected from the group consisting of ethylene tetrafluoride and vinylidene fluoride.
7. Among the structural units constituting the polymer, the first structural unit and a second structural unit selected from the group consisting of hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate, and methyl methacrylate are included. The method for producing an electrolyte sheet according to claim 6.
8. 方法 The method for producing an electrolyte sheet according to any one of claims 1 to 7, wherein the electrolyte salt is an imide-based lithium salt.
9. 方法 The method for producing an electrolyte sheet according to any one of claims 1 to 8, wherein the compound represented by the general formula (10) includes tetraethylene glycol dimethyl ether.
10. Forming a positive electrode mixture layer on the positive electrode current collector to obtain a positive electrode,
    Forming a negative electrode mixture layer on the negative electrode current collector to obtain a negative electrode,
    A step of disposing the electrolyte layer of the electrolyte sheet obtained by the production method according to any one of claims 1 to 9 between the positive electrode and the negative electrode;
    A method for manufacturing a secondary battery, comprising:

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