WO2019198715A1

WO2019198715A1 - Method for producing battery member for secondary batteries

Info

Publication number: WO2019198715A1
Application number: PCT/JP2019/015484
Authority: WO
Inventors: 由磨五行
Original assignee: 日立化成株式会社
Priority date: 2018-04-11
Filing date: 2019-04-09
Publication date: 2019-10-17
Also published as: TW201944646A; JPWO2019198715A1; JP7438605B2; TWI794472B

Abstract

The present invention provides a method for producing a battery member for secondary batteries, which comprises: a step for forming an electrode mixture intermediate layer, which contains an electrode active material, on one surface of a collector; and a step for applying a slurry, which contains oxide particles and a polymer, to a surface of the electrode mixture intermediate layer, said surface being on the reverse side of the collector-side surface. At least one of the electrode mixture intermediate layer and the slurry contains an ionic liquid and an electrolyte salt.

Description

Manufacturing method of battery member for secondary battery

The present invention relates to a method for producing a battery member for a secondary battery.

In recent years, with the spread of portable electronic devices, electric vehicles, etc., high-performance secondary batteries are required. Among them, lithium secondary batteries have been attracting attention as power sources for electric vehicle batteries, power storage batteries, and the like because of their high energy density. Specifically, lithium secondary batteries as batteries for electric vehicles include zero-emission electric vehicles that are not equipped with engines, hybrid electric vehicles that are equipped with both engines and secondary batteries, and plug-in hybrids that are charged directly from the power system. It is used in electric vehicles such as electric vehicles. In addition, lithium secondary batteries as power storage batteries are used in stationary power storage systems that supply power stored in advance in an emergency when the power system is shut off.

In order to use in such a wide range of applications, a lithium secondary battery having a higher energy density is demanded and developed. In particular, since lithium secondary batteries for electric vehicles require high safety in addition to high input / output characteristics and high energy density, more advanced technology for ensuring safety is required.

As a method for 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).

JP 2004-107641 A

However, when manufacturing a lithium secondary battery using a solid electrolyte, unlike a secondary battery using an electrolyte, the contact surface between the electrode mixture layer and the electrolyte layer becomes a solid / solid interface, and the electrode Since the contact surface between the electrode active material and the electrolyte in the mixture layer is also a solid / solid interface, it is difficult to make these interfaces adhere well. If these interfaces do not adhere well in the secondary battery, the internal resistance of the secondary battery increases, and the battery characteristics may deteriorate. Therefore, there is a demand for a technique that can easily and easily form the electrode mixture layer / electrolyte interface and the electrode active material / electrolyte interface in the electrode mixture layer.

The present invention provides a method for producing a battery member for a secondary battery in which the electrode active material / electrolyte interface in the electrode mixture layer is well formed and the inter-electrode adhesion in the electrode mixture layer / electrolyte layer is excellent. The purpose is to do.

The present invention includes a step of forming an electrode mixture intermediate layer containing an electrode active material on one surface of a current collector, and an oxide on a surface of the electrode mixture intermediate layer opposite to the current collector. Providing a slurry containing particles and a polymer, and at least one of the electrode mixture intermediate layer and the slurry contains an ionic liquid and an electrolyte salt.

In the present invention, one of the electrode mixture intermediate layer and the slurry may contain an ionic liquid and an electrolyte salt. In this case, the slurry may contain an ionic liquid and an electrolyte salt.

In the present invention, both the electrode mixture intermediate layer and the slurry may contain an ionic liquid and an electrolyte salt.

The oxide particles may have a hydrophobic surface. The oxide particles having a hydrophobic surface are preferably surface-treated with a silicon-containing compound.

The silicon-containing compound is preferably at least one selected from the group consisting of halogen-containing alkylsilanes, alkoxysilanes, epoxy group-containing silanes, amino group-containing silanes, silazanes, and siloxanes.

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

Among the structural units constituting the polymer, preferably, there are 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. included.

The concentration of the electrolyte salt per unit volume of the ionic liquid is preferably 1.0 to 2.5 mol / L.

The production method of the present invention further includes a step of infiltrating a solution containing a polymer having a structural unit represented by the following formula (1) into the electrode mixture intermediate layer before the step of applying the electrolyte slurry. May be.

[In formula (1), X ⁻ represents a counter anion. ]

According to the present invention, a method for producing a battery member for a secondary battery in which an electrode active material / electrolyte interface in an electrode mixture layer is satisfactorily formed and the adhesion between layers in the electrode mixture layer / electrolyte layer is excellent. Can be provided.

It is a perspective view which shows the secondary battery which concerns on one Embodiment. It is a disassembled perspective view which shows one Embodiment of the electrode group of the secondary battery shown in FIG. It is a schematic cross section which shows the manufacturing method of the battery member for secondary batteries which concerns on 1st Embodiment. It is a schematic cross section which shows the manufacturing method of the battery member for secondary batteries which concerns on 2nd Embodiment. It is a disassembled perspective view which shows one Embodiment of the electrode group of the secondary battery which concerns on a modification. 10 is a SEM image obtained by observing a cross section of a battery member for a secondary battery according to Example 8.

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 components (including steps and the like) are not essential unless otherwise specified. The size of the component in each figure is conceptual, and the relative relationship of the size between the components is not limited to that shown in each figure.

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

In the present specification, the following abbreviations may be used.
[Py13] ⁺ : N-methyl-N-propylpyrrolidinium cation [EMI] ⁺ : 1-ethyl-3-methylimidazolium 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 CF 3) 2 -, bis (trifluoromethanesulfonyl) imide anion [F3C] ⁻ : C (SO ₂ F) ₃ ⁻ , tris (fluorosulfonyl) carbanion [BOB] ⁻ : B (O ₂ C ₂ O ₂ ) ₂ ⁻ , bisoxalate borate anion [P (DADMA)] [Cl]: Poly (diallyldimethylammonium) chloride [P (DADMA)] [TFSI]: Poly (Diallyl dimethyl ammonium) bis (trifluoromethanesulfonyl) imide

FIG. 1 is a perspective view showing a secondary battery according to an embodiment. As shown in FIG. 1, the secondary battery 1 includes an electrode group 2 composed of a positive electrode, a negative electrode, and an electrolyte layer, and a bag-shaped battery outer package 3 that houses the electrode group 2. A positive electrode current collecting tab 4 and a negative electrode current collecting tab 5 are provided on the positive electrode and the negative electrode, respectively. The positive electrode current collecting tab 4 and the negative electrode current collecting tab 5 protrude from the inside of the battery outer package 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 outer package 3 may be formed of, for example, a laminate film. The laminate film may be a laminate 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 an embodiment of the electrode group 2 of the secondary battery 1 shown in FIG. 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. A positive electrode current collector tab 4 is provided on the positive electrode current collector 9 of the positive electrode 6. 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. A negative electrode current collector tab 5 is provided on the negative electrode current collector 11 of the negative electrode 8.

In one embodiment, the electrode group 2A includes a first secondary battery battery member (positive electrode member) including the positive electrode current collector 9, the positive electrode mixture layer 10, and the electrolyte layer 7 in this order. You can see that. Similarly, the electrode group 2A includes a second secondary battery battery member (negative electrode member) including the negative electrode current collector 11, the negative electrode mixture layer 12, and the electrolyte layer 7 in this order. You can also see it. The method for producing 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 producing the positive electrode member or the negative electrode member.

[First Embodiment]
FIG. 3 is a schematic cross-sectional view showing a method for manufacturing a battery member for a secondary battery according to the first embodiment. In this manufacturing method, first, as shown in FIG. 3A, an electrode active material is contained on one surface (main surface) 13a of the current collector 13 (positive electrode current collector 9 or negative electrode current collector 11). Electrode mixture intermediate layer 14A (positive electrode mixture intermediate layer or negative electrode mixture intermediate layer) is formed (electrode mixture intermediate layer forming step).

In the electrode mixture intermediate layer forming step, the method of forming the electrode mixture intermediate layer 14A on the one surface 13a of the current collector 13 is as follows. In one embodiment, the electrode mixture slurry is applied on the one surface 13a of the current collector 13. It is a method to do. The electrode mixture slurry is a slurry (positive electrode mixture slurry or negative electrode mixture slurry) in which the material contained in the positive electrode mixture layer 10 or the negative electrode mixture layer 12 is dispersed in a dispersion medium. The electrode mixture slurry of this embodiment contains at least an electrode active material (positive electrode active material or negative electrode active material) and a dispersion medium.

When the battery member is a positive electrode member, the current collector 13 is the positive electrode current collector 9. The positive electrode current collector 9 may be a metal such as aluminum, titanium, or tantalum, or an alloy thereof. Since the positive electrode current collector 9 is light and has a high weight energy density, it is preferably aluminum or an alloy thereof. The thickness of the positive electrode current collector 9 may be 10 μm or more and may be 100 μm or less.

When the battery member is a negative electrode member, the current collector 13 is the negative electrode current collector 11. The negative electrode current collector 11 may be a metal such as aluminum, copper, nickel, stainless steel, or an alloy thereof. The negative electrode current collector 11 is preferably aluminum or an alloy thereof because it is lightweight and has a high weight energy density. The negative electrode current collector 11 is preferably 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 may be 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.

The lithium transition metal oxide may be, for example, lithium manganate, lithium nickelate, lithium cobaltate, or the like. Lithium transition metal oxide is a part of transition metals such as Mn, Ni, Co, etc. contained in lithium manganate, lithium nickelate, lithium cobaltate, etc., 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 also be used. That is, the lithium transition metal oxide may be a compound represented by LiM ¹ O ₂ or LiM ¹ O ₄ (M ¹ includes at least one transition metal). Specifically, lithium transition metal oxides are 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. It may be ₄ mag.

From the viewpoint of further improving the energy density, the lithium transition metal oxide is preferably a compound represented by the following formula (2).
_{_{_{^{Li a Ni b Co c M 2}}}} d O 2 + e (2)
Wherein (2), ^{M 2} is at least one Al, Mn, selected from the group consisting of Mg and Ca, a, b, c, d and e are each 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 phosphates are 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 Zr) Or at least one element selected from the group consisting of:

The positive electrode active material may be primary particles that are not granulated, or may be secondary particles that are granulated.

The particle diameter 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 are coarse particles having a particle size equal to or larger than the thickness of the positive electrode mixture layer 10 in the positive electrode active material, the coarse particles are removed in advance by sieving classification, wind classification, etc. A positive electrode active material having a diameter is selected.

The average particle diameter of the positive electrode active material is preferably 0.1 μm or more, more preferably 1 μm or more. 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 diameter (D ₅₀ ) of the positive electrode active material is measured by suspending the positive electrode active material in water by a laser scattering method using a laser scattering particle size measuring device (for example, Microtrack). Can be obtained.

The content of the positive electrode active material is 70% by mass or more, 80% by mass or more, or 90% by mass or more based on the total amount of nonvolatile components in the positive electrode mixture slurry (a component obtained by removing the dispersion medium from the positive electrode mixture slurry) It may be 99% by mass or less. Thereby, content of the positive electrode active material in the positive electrode mixture layer obtained becomes content similar to content mentioned above.

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, those commonly used in the field of energy devices can be used. Specific examples of the negative electrode active material include metal lithium, lithium titanate (Li ₄ Ti ₅ O ₁₂ ), a lithium alloy or other metal compound, 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. Carbon materials include natural graphite (flaky graphite, etc.), graphite such as artificial graphite, amorphous carbon, carbon fiber, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal Examples thereof include carbon black such as black. 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 other metals). Good.

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 due to a decrease in particle diameter and has improved electrolyte salt retention ability. More preferably, it is 5 μm or more, more preferably 10 μm or more, preferably 50 μm or less, more preferably 40 μm or less, and 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 positive electrode active material described above.

The content of the negative electrode active material is 60% by mass or more, 65% by mass or more, or 70% by mass or more based on the total amount of nonvolatile components in the negative electrode mixture slurry (a component obtained by removing the dispersion medium from the negative electrode mixture slurry). It may be 99 mass% or less, 95 mass% or less, or 90 mass% or less. Thereby, content of the negative electrode active material in the obtained negative mix layer becomes content similar to content mentioned above.

The dispersion medium may be water or an organic solvent. The organic solvent may be N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide, methyl ethyl ketone, toluene, 2-butanol, cyclohexanone, ethyl acetate, 2-propanol, and preferably NMP. The content of the dispersion medium in the electrode mixture slurry is, for example, 20 parts by mass or more with respect to 100 parts by mass of the nonvolatile content in the electrode mixture slurry (component obtained by removing the dispersion medium from the electrode mixture slurry). It may be 1000 parts by mass or less.

The electrode mixture slurry may further contain an ionic liquid, an electrolyte salt, a conductive agent, a binder and the like as other components. In this case, an electrode mixture intermediate layer 14A further containing these materials is formed.

In one embodiment, the electrode mixture slurry contains an ionic liquid and an electrolyte salt. In this case, the electrode mixture slurry may contain an ionic liquid and an electrolyte salt as an “ionic liquid electrolytic solution” in which the electrolyte salt is dissolved in the ionic liquid. The electrode mixture slurry may not contain an ionic liquid and an electrolyte salt. In that case, a slurry (electrolyte slurry) described later contains an ionic liquid and an electrolyte salt. That is, at least one of the electrode mixture slurry and the electrolyte slurry contains an ionic liquid and an electrolyte salt.

When the slurry (electrolyte slurry) described later contains oxide particles having a hydrophobic surface, the electrode mixture slurry preferably does not contain an ionic liquid and an electrolyte salt.

The ionic liquid contains the following anion component and cation component. Note that the ionic liquid in this specification is a liquid substance at −20 ° C. or higher.

The anion component of the ionic liquid is not particularly limited, but is an anion of a halogen such as Cl ⁻ , Br ⁻ and I ⁻ , an inorganic anion such as BF ₄ ⁻ and N (SO ₂ F) ₂ ^— , 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 ⁻ Or an organic anion. The anionic component of the ionic liquid preferably contains at least one anionic component represented by the following formula (3).
N (SO ₂ C _m F _{2m + 1} ) (SO ₂ C _n F _{2n + 1} ) ⁻ (3)
[In Formula (3), m and n each independently represents an integer of 0 to 5. m and n may be the same as or different from each other, and are preferably the same as each other. ]

Examples of the anion component represented by the formula (3) include 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 with a relatively low viscosity and further improving the charge / discharge characteristics. Contains 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 Contains N (SO ₂ F) ₂ ^— .

The cation component of the ionic liquid 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 formula (4).

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

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

The pyrrolidinium cation is, for example, a five-membered cyclic compound represented by the following formula (6).

[In Formula (6), R ⁷ and R ⁸ are each independently an alkyl group having 1 to 20 carbon atoms, or an alkoxyalkyl group represented by R—O— (CH ₂ ) _n — (R is methyl And n represents an integer of 1 to 4. The carbon number of the alkyl group represented by R ⁷ and R ⁸ is preferably 1-20, more preferably 1-10, and still more preferably 1-5. ]

The pyridinium cation is, for example, a compound represented by the following formula (7).

[In the formula (7), R ⁹ to R ¹³ each independently represents an alkyl group having 1 to 20 carbon atoms, an alkoxyalkyl group represented by R—O— (CH ₂ ) _n — (R represents a methyl group) Or an ethyl group, and n represents an integer of 1 to 4), or a hydrogen atom. The number of carbon atoms 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 following formula (8).

[In the formula (8), R ¹⁴ to R ¹⁸ are each independently an alkyl group having 1 to 20 carbon atoms, an alkoxyalkyl group represented by R—O— (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 number of carbon atoms 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. ]

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

The anion component of the electrolyte salt includes 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 component represented by the above formula (3) such as N (SO ₂ F) ₂ ⁻ , N (SO ₂ CF ₃ ) ₂ ^— , PF ₆ ⁻ , BF ₄ ^−. , B (O ₂ C ₂ O ₂ ) ₂ ⁻ , or ClO ₄ ^— .

Lithium salts include LiPF ₆ , LiBF ₄ , Li [FSI], Li [TFSI], Li [f ₃ C], 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 having 1 to 4 carbon atoms) , A phenyl group, or a naphthyl group).

Sodium salts include NaPF ₆ , NaBF ₄ , Na [FSI], Na [TFSI], Na [f ₃ C], 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 an alkyl group having 1 to 4 carbon atoms) , A phenyl group, or a naphthyl group).

The calcium salts are 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 alkyl group having 1 to 4 carbon atoms, phenyl Or at least one selected from the group consisting of a naphthyl group).

Magnesium salts are Mg (PF ₆ ) ₂ , Mg (BF ₄ ) ₂ , Mg [FSI] ₂ , Mg [TFSI] ₂ , Mg [f 3 C] 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 having 1 to 4 carbon atoms, a phenyl group Or a naphthyl group) may be at least one selected from the group consisting of:

Among these, from the viewpoint of dissociation property and electrochemical stability, the electrolyte salt is preferably LiPF ₆ , LiBF ₄ , Li [FSI], Li [TFSI], Li [f 3 C], 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, It is at least one selected from the group consisting of LiCF ₃ COO and LiRCOO (where R is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group), more preferably Li [TFSI], Li _{_{[FSI], LiPF 6, LiBF}} 4, Li [BOB], and at least one selected from the group consisting of LiClO _4, more preferably Li [TF I], and is one selected from the group consisting of Li [FSI].

When the electrode mixture slurry contains an ionic liquid and an electrolyte salt as the ionic liquid electrolyte, the salt concentration of the electrolyte salt per unit volume of the ionic liquid in the ionic liquid electrolyte is 0.3 mol / L or more, 0. It may be 5 mol / L or more, or 1.0 mol / L or more, and may be 3.0 mol / L or less, 2.7 mol / L or less, or 2.5 mol / L or less.

When the electrode mixture slurry contains an ionic liquid electrolyte, the content of the ionic liquid electrolyte (the total of the contents of the ionic liquid and the electrolyte salt) is determined from the viewpoint of improving the ionic conductivity of the electrode mixture layer. It is preferably 3% by mass or more, more preferably 5% by mass or more, and further preferably 10% by mass or more, based on the total amount of nonvolatile content in the mixture slurry, and the strength of the electrode mixture layer From the viewpoint of increasing, it is preferably 30% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass or less.

The conductive agent is not particularly limited, and may be a carbon material such as graphite, acetylene black, carbon black, or carbon fiber. The conductive agent may be a mixture of two or more carbon materials described above. The content of the conductive agent may be 1 to 70% by mass based on the total nonvolatile content in the electrode mixture slurry. Thereby, content of the electrically conductive agent in the electrode mixture layer obtained becomes content similar to content mentioned above.

The binder is not particularly limited, but contains as a monomer unit at least one selected from the group consisting of ethylene tetrafluoride, vinylidene fluoride, hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate, and methyl methacrylate. It may be a polymer, rubber such as styrene-butadiene rubber, isoprene rubber or acrylic rubber. The binder is preferably a copolymer containing hexafluoropropylene and vinylidene fluoride as structural units. The content of the binder may be 1 to 70% by mass based on the total nonvolatile content in the electrode mixture slurry. Thereby, content of the binder in the obtained electrode mixture layer becomes content similar to content mentioned above.

In the electrode mixture intermediate layer forming step, examples of the method of applying the electrode mixture slurry include a method of applying using an applicator and a method of applying by spraying. By these methods, an electrode mixture slurry is applied onto one surface 13a of the current collector 13. As a result, as shown in FIG. 3A, an electrode mixture intermediate layer 14 </ b> A is formed on one surface 13 a of the current collector 13.

In the electrode mixture intermediate layer forming step, after applying the electrode mixture slurry, the dispersion medium in the slurry may be volatilized. That is, the “electrode mixture intermediate layer” in this specification includes a layer formed of an electrode mixture slurry and a layer formed by volatilization of a part or all of the dispersion medium from the electrode mixture slurry. It is. The method of volatilizing the dispersion medium may be, for example, a method of drying by heating, a method of reducing pressure, a method of combining reduced pressure and heating, or the like. In the method of reducing the pressure, the pressure may be reduced to a vacuum state. The drying temperature may be 50 to 150 ° C., and the heating time may be changed depending on the temperature as long as the dispersion medium is sufficiently volatilized, but is, for example, 1 minute to 48 hours.

Subsequent to the electrode mixture intermediate layer forming step, as shown in FIG. 3B, the oxide particles 16, the polymer 17, and the electrode mixture intermediate layer 14 </ b> A on the surface 14 a opposite to the current collector 13. A slurry 15A containing a dispersion medium is applied. Hereinafter, this slurry is also referred to as “electrolyte slurry”, and the step of applying the electrolyte slurry 15A is also referred to as “electrolyte slurry application step”.

The oxide particles 16 are, for example, inorganic oxide particles. The inorganic oxide is an inorganic oxide containing, for example, Li, Mg, Al, Si, Ca, Ti, Zr, La, Na, K, Ba, Sr, V, Nb, B, Ge and the like as constituent elements. Good. The oxide particles 16 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 16 have polarity, it is possible to promote dissociation of the electrolyte in the electrolyte layer and improve battery characteristics.

The oxide particles 16 may be rare earth metal oxides. Specifically, the oxide particles 16 are scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide, eurobium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, It may be thulium oxide, ytterbium oxide, lutetium oxide or the like.

The oxide particles 16 may have a hydrophobic surface. The oxide particles usually have a hydroxyl group on the surface and tend to be hydrophilic. The oxide particles having a hydrophobic surface have fewer hydroxyl groups on the surface than the oxide particles having no hydrophobic surface. Therefore, when oxide particles having a hydrophobic surface are used, the electrolyte slurry contains an ionic liquid (for example, the anion component has N (SO ₂ F) ₂ ⁻ , N (SO ₂ CF ₃ ) ₂ ^−, etc. Since the ionic liquid) and the ionic liquid are hydrophobic, it is expected that the affinity between the oxide particles and the ionic liquid is improved. Therefore, it is considered that the ionic liquid retention in the electrolyte layer 7 is further improved, and as a result, the ionic conductivity of the electrolyte layer 7 is improved. In addition, in the secondary battery including the electrolyte layer 7 including oxide particles having a hydrophobic surface, discharge characteristics can be particularly improved.

The oxide particles having a hydrophobic surface can be obtained, for example, by treating hydrophilic oxide particles with a surface treatment agent capable of imparting a hydrophobic surface. That is, the oxide particles having a hydrophobic surface mean oxide particles that have been surface-treated with a surface treatment agent. The surface treatment agent is preferably a silicon-containing compound.

The oxide particles 16 may be surface-treated with a silicon-containing compound. That is, the oxide particle 16 may be one in which the surface of the oxide particle and the silicon atom of the silicon-containing compound are bonded via an oxygen atom. The silicon-containing compound is preferably at least one selected from the group consisting of halogen-containing alkylsilanes, alkoxysilanes, epoxy group-containing silanes, amino group-containing silanes, silazanes, and siloxanes.

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

Alkoxysilanes are methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxydiphenylsilane, n-propyltrimethoxysilane, hexyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldi It may be ethoxysilane, n-propyltriethoxysilane, or the like.

Epoxy group-containing silanes are 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxy. Silane, 3-glycidoxypropyltriethoxysilane and the like may be used.

Amino group-containing silanes are N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N- Phenyl-3-aminopropyltrimethoxysilane or the like may be used.

Silazane may be hexamethyldisilazane or the like. Siloxane may be dimethyl silicone oil or the like. One or both of these terminals may have a reactive functional group (for example, a carboxyl group).

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

The oxide particles 16 generally include primary particles that integrally form a single particle (particles that do not constitute a secondary particle) and a plurality of primary particles, as determined from an apparent geometric form. Secondary particles formed by the aggregation of the particles may be included.

The specific surface area of the oxide particles 16 may be 2 to 500 m ² / g, 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. May be. When the specific surface area is 2 to 500 m ² / g, the secondary battery including the electrolyte layer containing such oxide particles tends to have excellent 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 more, or 50 m ² / g or more, 500 m ² / g or less, 400 m ² / g or less, 350 m ² / g or less, 300 m ² / g or less, 200 m ² / g or less, 100 m ² / g or less, 90 m ² / g or less, 80 m ² / g or less, or 60 m ² / g or less may be sufficient. The specific surface area of the oxide particles 16 means the specific surface area of the whole oxide particles including primary particles and secondary particles, and is measured by the BET method.

The average primary particle size of the oxide particles 16 (average particle size of the primary particles) is preferably 0.005 μm (5 nm) or more, more preferably 0.01 μm, from the viewpoint of improving the conductivity of the secondary battery 1. (10 nm) or more, more preferably 0.015 μm (15 nm) or more. From the viewpoint of making the electrolyte layer 7 thin, the average primary particle size of the oxide particles 16 is preferably 1 μm or less, more preferably 0.1 μm or less, and even more preferably 0.05 μm or less. The average primary particle size 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 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 16 is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less. The average particle diameter of the oxide particles 16 is measured by a laser diffraction method, and corresponds to the particle diameter at which the volume accumulation is 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 5% by mass or more, more preferably 10% by mass or more, based on the total amount of nonvolatile components (components obtained by removing the dispersion medium from the electrolyte slurry) in the electrolyte slurry 15A. More preferably, it is 15% by mass or more, particularly preferably 20% by mass or more, preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less. is there. Thereby, content of the oxide particle 16 in the obtained electrolyte layer turns into content similar to content mentioned above.

Polymer 17 preferably has a first structural unit selected from the group consisting of ethylene tetrafluoride and vinylidene fluoride.

The polymer 17 is preferably one or more polymers, and among the structural units constituting the one or more polymers, the first structural unit, hexafluoropropylene, acrylic A second structural unit selected from the group consisting of acid, maleic acid, ethyl methacrylate, and methyl methacrylate may be included. That is, the first structural unit and the second structural unit may be included in one kind of polymer to form a copolymer, and each of the first structural unit and the second structural unit may be included in another polymer and have the first structural unit. And at least two types of polymers, the second polymer having the second structural unit.

More specifically, the polymer 17 may be polytetrafluoroethylene, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, or the like. The polymer 17 is preferably a copolymer of vinylidene fluoride and hexafluoropropylene from the viewpoint of improving battery characteristics.

The content of the polymer 17 is preferably 3% by mass or more, preferably 50% by mass or less, more preferably 40% by mass or less, based on the total nonvolatile content in the electrolyte slurry 15A. . Thereby, content of the polymer 17 in the obtained electrolyte layer turns into content similar to content mentioned above.

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

The electrolyte slurry 15A may further contain an ionic liquid and an electrolyte salt in addition to the oxide particles 16, the polymer 17, and the dispersion medium. In this case, the electrolyte slurry 15A may contain an ionic liquid and an electrolyte salt as the ionic liquid electrolytic solution. The electrolyte slurry 15A may not contain an ionic liquid and an electrolyte salt. In this case, the electrode mixture slurry contains an ionic liquid and an electrolyte salt.

When the electrolyte slurry 15A contains an ionic liquid and an electrolyte salt, the ionic liquid and the electrolyte salt may be the same as the ionic liquid and the electrolyte salt contained in the electrode mixture slurry described above. The ionic liquid and electrolyte salt that can be contained in the electrolyte slurry may be the same as or different from the ionic liquid and electrolyte salt contained in the electrode mixture slurry, respectively.

When the electrolyte slurry 15A contains an ionic liquid and an electrolyte salt as the ionic liquid electrolyte, the salt concentration of the electrolyte salt per unit volume of the ionic liquid in the ionic liquid electrolyte is 0.3 mol / L or more, 0.5 mol / L L or more, 1.0 mol / L or more, 1.2 mol / L or more, or 1.5 mol / L or more, 3.0 mol / L or less, 2.7 mol / L or less, 2.5 mol / L or less, It may be 2.3 mol / L or less, or 2.0 mol / L or less. In the ionic liquid electrolyte, the salt concentration of the electrolyte salt per unit volume of the ionic liquid is 0.3 to 3.0 mol / L, 0.3 to 2.7 mol / L, 0.3 to 2.5 mol / L, 0.3 to 2.3 mol / L, 0.3 to 2.0 mol / L, 0.5 to 3.0 mol / L, 0.5 to 2.7 mol / L, 0.5 to 2.5 mol / L, 0.5 to 2.3 mol / L, 0.5 to 2.0 mol / L, 1.0 to 3.0 mol / L, 1.0 to 2.7 mol / L, 1.0 to 2.5 mol / L, 1.0-2.3 mol / L, 1.0-2.0 mol / L, 1.2-3.0 mol / L, 1.2-2.7 mol / L, 1.2-2.5 mol / L, 1.2-2.3 mol / L, 1.2-2.0 mol / L, 1.5-3.0 mol / L, 1.5-2.7 mol / L, 1.5-2.5 mol L, it may be 1.5 ~ 2.3mol / L, or 1.5 ~ 2.0mol / L.

When the electrolyte slurry 15A contains an ionic liquid electrolytic solution, the content of the ionic liquid electrolytic solution (the total content of the ionic liquid and the electrolyte salt) is obtained from the viewpoint of obtaining a uniform dispersed state in the electrolyte slurry, and an electrode mixture From the viewpoint of satisfactorily forming the interface between the layer (the positive electrode mixture layer 10 or the negative electrode mixture layer 12) and the electrolyte layer 7, it is preferably 20% by mass or more based on the total amount of nonvolatile components in the electrolyte slurry 15A. Preferably it is 30 mass% or more, More preferably, it is 40 mass% or more. Thereby, the ionic conductivity of the electrolyte layer 7 can be raised and the battery characteristic of a secondary battery can be improved further. The content of the ionic liquid electrolytic solution may be 90% by mass or less, 85% by mass or less, or 80% by mass or less based on the total nonvolatile content in the electrolyte slurry 15.

In the electrolyte slurry 15A, the content ratio of the oxide particles 16 and the polymers 17 is a mass ratio from the viewpoint of improving the load characteristics of the secondary battery, and the oxide particles: polymer = 1: 0.5 to 1: 5. It may be. From the same viewpoint, the ratio of the content of the oxide particles 16 and the ionic liquid electrolyte may be a volume ratio of oxide particles: ionic liquid electrolyte = 1: 0 to 1:15.

In the electrolyte slurry 15, the content ratio of the oxide particles 16, the polymer 17, and the ionic liquid electrolyte is mass ratio, and the oxide particles: polymer: ionic liquid electrolyte = 6 to 67: 5 to 83: 0 to 86 It may be. The content ratio of the oxide particles 16, the polymer 17 and the ionic liquid electrolyte may be a mass ratio of oxide particles: polymer: ionic liquid electrolyte = 9 to 28: 9 to 65:14 to 83. .

In the electrolyte slurry application step, the method of applying the electrolyte slurry 15A on the one surface 14a of the electrode mixture intermediate layer 14A is the same as the method of applying the electrode mixture slurry described above on the one surface 13a of the current collector 13. Good. The method of applying the electrolyte slurry 15A may be the same as or different from the method of applying the electrode mixture slurry.

After the electrolyte slurry application step, the dispersion medium contained in the electrode mixture intermediate layer 14A and the electrolyte slurry 15A is volatilized. The method for volatilizing the dispersion medium may be the same as the method for volatilizing the dispersion medium in the electrode mixture slurry described above. As a result of volatilizing the dispersion medium of the electrode mixture intermediate layer 14A and the electrolyte slurry 15A, as shown in FIG. 3C, the current collector 13, the electrode mixture layer 18A (the positive electrode mixture layer 10 or the negative electrode mixture layer) 12) and a battery member 19A (positive electrode member or negative electrode member) including the electrolyte layer 7A in this order can be obtained.

In the manufacturing method of this embodiment, at least one of the electrode mixture intermediate layer 14A or the electrolyte slurry 15A contains an ionic liquid and an electrolyte salt (ionic liquid electrolytic solution). Then, when the electrolyte slurry 15A is applied onto the electrode mixture intermediate layer 14A, as shown by the arrow in FIG. 3B, the ionic liquid electrolytic solution is mixed with the dispersion medium from the electrode mixture intermediate layer 14A. It moves to 15A, moves from the electrolyte slurry 15A to the electrode mixture intermediate layer 14A, or moves between the electrode mixture intermediate layer 14A and the electrolyte slurry 15A. This movement is presumed to be based on the action of reducing the concentration difference of the ionic liquid electrolyte between the electrode mixture intermediate layer 14A and the electrolyte slurry 15A, the action of gravity, or the capillary phenomenon.

According to the manufacturing method of this embodiment, since the electrolyte layer 7A is formed by applying the electrolyte slurry 15A on the electrode mixture intermediate layer 14A, there are fine irregularities on the surface of the electrode mixture intermediate layer 14A. Also, the electrolyte slurry 15A is arranged so as to fill and flatten the recess. As a result, in the obtained battery member 19A, a good interface is formed in which the electrode mixture layer 18A and the electrolyte layer 7A are closely adhered. In the battery member 19A, the ionic liquid electrolyte solution can move between the electrolyte slurry 15A and the electrode mixture intermediate layer 14A in the electrolyte slurry application step. The electrolyte tends to exist around the electrode active material. Therefore, in the battery member 19A, the electrode active material / electrolyte interface is well formed.

Thus, in the battery member 19A, the electrode mixture layer 18A / electrolyte layer 7A interface is well formed and has excellent adhesion, and the electrode active material / electrolyte interface is also well formed. Therefore, the secondary battery using this battery member 19A is excellent in battery characteristics such as discharge characteristics.

[Second Embodiment]
Next, the manufacturing method of the battery member for secondary batteries which concerns on 2nd Embodiment is demonstrated. FIG. 4 is a schematic cross-sectional view illustrating a method for manufacturing a battery member for a secondary battery according to the second embodiment. In this manufacturing method, first, as shown in FIG. 4A, an electrode mixture intermediate containing an electrode active material is provided on one surface 13a of the current collector 13 (positive electrode current collector 9 or negative electrode current collector 11). The layer 14B is formed (electrode mixture intermediate layer forming step).

The electrode mixture intermediate layer forming step is performed by a method of applying an electrode mixture slurry onto the current collector 13 as in the first embodiment. The electrode mixture slurry contains at least an electrode active material and a dispersion medium. The types and contents of the electrode active material and the dispersion medium may be the same as the types and contents of the electrode active material and the dispersion medium in the first embodiment described above.

The electrode mixture slurry may further contain an ionic liquid, an electrolyte salt, a conductive agent, a binder and the like as other components. In this case, the electrode mixture intermediate layer 14B further containing these materials is formed.

In one embodiment, the electrode mixture slurry contains an ionic liquid and an electrolyte salt. In this case, the electrode mixture slurry may contain an ionic liquid and an electrolyte salt as the ionic liquid electrolytic solution. The electrode mixture slurry may not contain the ionic liquid and the electrolyte salt, but in that case, the slurry (electrolyte slurry) described later contains the ionic liquid. That is, at least one of the electrode mixture slurry and the electrolyte slurry contains an ionic liquid and an electrolyte salt.

When the electrode mixture slurry contains an ionic liquid and an electrolyte salt, the ionic liquid and the electrolyte salt may be the same as the ionic liquid and the electrolyte salt contained in the electrode mixture slurry in the first embodiment described above.

When the electrode mixture slurry contains an ionic liquid and an electrolyte salt as the ionic liquid electrolyte, the salt concentration of the electrolyte salt per unit volume of the ionic liquid in the ionic liquid electrolyte and the content of the ionic liquid electrolyte are: It may be the same as the range in the first embodiment described above.

The type and content of the conductive agent and the binder may be the same as the type and content of the conductive agent and the binder in the first embodiment described above.

Next, as shown in FIG. 4B, a polymer-containing solution (polymer solution) 20 is infiltrated into the electrode mixture intermediate layer 14B (polymer solution infiltration step).

In one embodiment, the polymer solution 20 contains a polymer having a structural unit represented by the following formula (1), an ionic liquid, and an electrolyte salt.

In the formula (1), X ⁻ represents a counter anion. Examples of X ⁻ include BF ₄ ⁻ (tetrafluoroborate anion), PF ₆ ⁻ (hexafluorophosphate anion), [FSI] ⁻ , [TFSI] ⁻ , [f3C] ⁻ , [BOB] ⁻ , and 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 represents an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group). Among these, X ⁻ is preferably at least one selected from the group consisting of BF ₄ ⁻ , PF ₆ ⁻ , [FSI] ⁻ , [TFSI] ⁻ , and [f3C] ⁻ , more preferably [TFSI] ^−. Or [FSI] ⁻ .

The viscosity average molecular weight Mv (g · mol ⁻¹ ) of the polymer having the structural unit represented by the formula (1) 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 5.0 × 10 ⁶ or less, and more preferably 1.0 × 10 ⁶ . Moreover, it exists in the tendency for the handleability at the time of making the polymer solution 20 penetrate | invade more that a viscosity average molecular weight is 5.0 * 10 < ⁶ > or less.

In this specification, the “viscosity average molecular weight” can be evaluated by a viscosity method which is a general measurement method. For example, from the intrinsic viscosity [η] measured based on JIS K 7367-3: 1999. Can be calculated.

The polymer having the structural unit represented by the formula (1) is preferably a polymer consisting only of the structural unit represented by the formula (1), that is, a homopolymer, from the viewpoint of ion conductivity.

The polymer having the structural unit represented by the formula (1) may be a polymer represented by the following formula (1A).

In the formula (1A), n is 300 to 4000, and Y ⁻ represents a counter anion. As Y ⁻ , those similar to those exemplified for X ⁻ can be used.

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 to 4000, preferably 400 to 3500, more preferably 500 to 3000.

Although the manufacturing method of the polymer which has a structural unit represented by Formula (1) is not restrict | limited in particular, For example, the manufacturing method of Journal of Power Sources 2009,188,558-563 can be used.

The polymer (X ⁻ = [TFSI] ⁻ ) having the structural unit represented by the formula (1) can be obtained, for example, by the following production method.

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

Thereafter, the molar ratio of Li [TFSI] to [P (DADMA)] [Cl] (molar amount of Li [TFSI] / molar amount of [P (DADMA)] [Cl]) was 1.2 to 2.0. The two aqueous solutions are mixed and stirred for 2 to 8 hours to precipitate a solid, and the obtained solid is collected by filtration. The polymer having the structural unit represented by the formula (1) ([P (DADMA)] [TFSI]) can be obtained by washing the solid with deionized water and vacuum drying for 12 to 48 hours. .

The polymer having the structural unit represented by the formula (1) is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more, based on the total amount of the polymer solution. Moreover, it is preferably 80% by mass or less, more preferably 75% by mass or less, and further preferably 70% by mass or less.

The ionic liquid and electrolyte salt contained in the polymer solution 20 may be the same as the ionic liquid and electrolyte salt that can be used in the first embodiment described above. The ionic liquid and electrolyte salt contained in the polymer solution 20 may be the same as or different from the ionic liquid and electrolyte salt contained in the electrode mixture slurry of the second embodiment.

The ionic liquid and the electrolyte salt may be added to the polymer solution 20 as an ionic liquid electrolytic solution. In this case, 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. It may be 0.0 mol / L or less, 2.7 mol / L or less, or 2.5 mol / L or less.

The content of the ionic liquid electrolytic solution is preferably 3% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and preferably 80% based on the total amount of the polymer solution. It is not more than mass%, more preferably not more than 75 mass%, still more preferably not more than 70 mass%.

The polymer solution 20 may further contain a dispersion medium. The dispersion medium may be an organic solvent, such as acetone, ethyl methyl ketone, γ-butyrolactone, and the like.

In the polymer solution infiltration step, as shown in FIG. 4B, the method of infiltrating the polymer solution 20 into the electrode mixture intermediate layer 14B is a surface 14a on the opposite side of the current collector 13 of the electrode mixture intermediate layer 14B. In this method, the polymer solution 20 is applied on top. The application may be application by an applicator, application by spraying, or the like. The polymer solution 20 applied on the electrode mixture intermediate layer 14B penetrates into the electrode mixture intermediate layer 14B as shown by the arrow in FIG. 4B, and the structural unit represented by the formula (1) is expressed. An electrode mixture intermediate layer 14C containing the polymer is formed (FIG. 4C).

The method of allowing the polymer solution 20 to penetrate into the electrode mixture intermediate layer 14B may be a method of immersing the current collector 13 on which the electrode mixture intermediate layer 14B is formed in the polymer solution 20 as another method. Good.

Thereafter, as shown in FIG. 4 (d), on the surface 14a opposite to the current collector 13 of the electrode mixture intermediate layer 14C (electrode mixture intermediate layer infiltrated with the polymer solution), the oxide particles 16, A slurry 15B (electrolyte slurry 15B) containing polymer 17 and a dispersion medium is applied. (Electrolyte slurry coating process).

The types and contents of the oxide particles 16, the polymer 17 and the dispersion medium contained in the electrolyte slurry 15B are the same as the types and contents of the oxide particles 16, the polymer 17 and the dispersion medium in the first embodiment described above. It may be. The oxide particles 16 may have a hydrophobic surface and may be surface-treated with the above-described surface treatment agent.

The electrolyte slurry 15B may further contain an ionic liquid and an electrolyte salt. In this case, the electrolyte slurry 15A may contain an ionic liquid and an electrolyte salt as the ionic liquid electrolytic solution. The ionic liquid and the electrolyte salt may be the same as the ionic liquid and the electrolyte salt included in the electrolyte slurry in the first embodiment described above. The ionic liquid and electrolyte salt contained in the electrolyte slurry 15B may be the same as or different from the ionic liquid and electrolyte salt contained in the electrode mixture slurry and polymer solution 20 of the second embodiment. The electrolyte slurry 15B may not contain an ionic liquid and an electrolyte salt.

When the electrolyte slurry 15B contains an ionic liquid and an electrolyte salt as the ionic liquid electrolytic solution, the salt concentration of the electrolyte salt per unit volume of the ionic liquid and the content of the ionic liquid electrolytic solution in the ionic liquid electrolytic solution are as described above. It may be the same as the range in the first embodiment.

In the electrolyte slurry 15B, the ratio of the content of the oxide particles 16 and the polymer 17, the ratio of the content of the oxide particles 16 and the ionic liquid electrolyte, and the content of the oxide particles 16, the polymer 17 and the ionic liquid electrolyte The ratio may be the same as the range of the composition ratio in the first embodiment described above.

The method of applying the electrolyte slurry 15B may be performed by the same method as the electrolyte slurry applying step in the first embodiment described above. The method of applying the electrolyte slurry 15B may be the same as or different from the method of applying the electrode mixture slurry in the second embodiment.

After the electrolyte slurry coating step, the dispersion medium of the electrode mixture intermediate layer 14C and the electrolyte slurry 15B is volatilized. The method for volatilizing the dispersion medium may be the same as the method in the first embodiment described above. As a result of volatilizing the dispersion medium, as shown in FIG. 4E, the current collector 13, the electrode mixture layer 18B (the positive electrode mixture layer 10 or the negative electrode mixture layer 12), and the electrolyte layer 7B are provided in this order. A battery member 19B (positive electrode member or negative electrode member) for the secondary battery can be obtained.

Also in the manufacturing method of the present embodiment, at least one of the electrode mixture intermediate layer 14C or the electrolyte slurry 15B contains an ionic liquid and an electrolyte salt (ionic liquid electrolytic solution). Then, when the electrolyte slurry 15B is applied onto the electrode mixture intermediate layer 14C, the ionic liquid electrolyte moves from the electrode mixture intermediate layer 14C to the electrolyte slurry 15B together with the dispersion medium, or from the electrolyte slurry 15B to the electrode mixture 15B. It moves to the agent intermediate layer 14C or moves between the electrode mixture intermediate layer 14C and the electrolyte slurry 15B. This movement is presumed to be based on the action of reducing the concentration difference of the ionic liquid electrolyte between the electrode mixture intermediate layer 14C and the electrolyte slurry 15B, the action of gravity, or the capillary phenomenon.

Even in the manufacturing method of the present embodiment, since the electrolyte layer 7B is formed by applying the electrolyte slurry 15B on the electrode mixture intermediate layer 14C, even if fine irregularities exist on the surface of the electrode mixture intermediate layer 14C. The electrolyte slurry 15B is disposed so as to fill and flatten the recess. As a result, in the obtained battery member 19B, a good interface in which the electrode mixture layer 18B and the electrolyte layer 7B are closely adhered is formed. In the battery member 19B, the ionic liquid electrolyte solution can move between the electrolyte slurry 15B and the electrode mixture intermediate layer 14C in the electrolyte slurry application step. The electrolyte tends to exist around the electrode active material. Therefore, also in the battery member 19B, the electrode active material / electrolyte interface is satisfactorily formed.

Thus, in the battery member 19B, the electrode mixture layer 18B / electrolyte layer 7B interface is well formed and has excellent adhesion, and the electrode active material / electrolyte interface is also well formed. Therefore, the secondary battery using the battery member 19B is excellent in battery characteristics such as discharge characteristics.

Furthermore, in the battery member 19B, the polymer represented by the above formula (1) is included in the electrode mixture layer 18B. Thereby, the ion conductivity of the electrode mixture layer 18B can be increased, and the battery characteristics of the secondary battery using the battery member 19B can be further improved.

The secondary battery including the battery member manufactured according to each embodiment described above can take various modifications.

As a first modification, the battery member manufacturing method according to each of the above-described embodiments can also be used as a battery member manufacturing method used for a so-called bipolar secondary battery. FIG. 5 is an exploded perspective view showing an embodiment of an electrode group of a secondary battery according to a modification. The difference between the secondary battery in the present modification and the secondary battery in the above-described embodiment is that the electrode group 2 </ b> B includes the bipolar electrode 21. That is, as shown in FIG. 5, the electrode group 2 </ b> B includes the positive electrode 6, the first electrolyte layer 7, the bipolar electrode 21, the second electrolyte layer 7, and the negative electrode 8 in this order. The bipolar electrode 21 includes a bipolar current collector 22, a positive electrode mixture layer 10 provided on a surface (positive electrode surface) on the negative electrode 8 side of the bipolar current collector 22, and a surface on the positive electrode 6 side of the bipolar current collector 22 ( And a negative electrode mixture layer 12 provided on the negative electrode surface).

This bipolar secondary battery includes a first electrolyte layer 7, a positive electrode mixture layer 10, a bipolar current collector 22, a negative electrode mixture layer 12, and a second electrolyte layer 7 in this order. It can be seen that a battery battery member (bipolar electrode member) is included. The battery member manufacturing method according to an embodiment of the present invention is a method of manufacturing this bipolar electrode member.

The method for manufacturing a bipolar electrode member according to one embodiment includes a step of forming a positive electrode mixture intermediate layer on one surface of the bipolar current collector 22 (positive electrode mixture intermediate layer forming step), and a positive electrode mixture intermediate layer A step of applying a first electrolyte slurry on the surface opposite to the bipolar current collector 22 (first electrolyte slurry applying step), and a negative electrode mixture intermediate layer on the other surface of the bipolar current collector 22 A step of forming (a negative electrode mixture intermediate layer forming step) and a step of applying a second electrolyte slurry on the surface of the negative electrode mixture intermediate layer opposite to the bipolar current collector 22 (second electrolyte slurry applying step) And). Each process may be implemented by the same material and method as each process (electrode mixture intermediate layer forming process, electrolyte slurry coating process) in each embodiment described above. 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.

Also in this embodiment, before the electrolyte slurry coating step, a solution containing a polymer having the structural unit represented by the above formula (1) is infiltrated into the positive electrode mixture intermediate layer or the negative electrode mixture intermediate layer. A step (polymer solution infiltration step) may be further provided. The polymer solution infiltration step may be performed by the same material and method as the polymer solution infiltration step in the above-described embodiment.

After the electrolyte slurry application step, the positive electrode mixture intermediate layer and the first electrolyte slurry dispersion medium are volatilized. Similarly, the dispersion medium of the negative electrode mixture intermediate layer and the second electrolyte slurry is volatilized. The method for volatilizing the dispersion medium may be the same as the method in the above-described embodiment. As a result of volatilizing the dispersion medium, a battery member for a secondary battery comprising the first electrolyte layer 7, the positive electrode mixture layer 10, the bipolar current collector 22, the negative electrode mixture layer 12, and the second electrolyte layer 7 in this order. (Bipolar electrode member) can be obtained.

Even in the bipolar electrode member thus obtained, the interface of the positive electrode mixture layer / first electrolyte layer and the interface of the negative electrode mixture layer / second electrolyte layer are well formed and excellent in adhesion. Also, the electrode active material / electrolyte interface is well formed. Therefore, a secondary battery (bipolar secondary battery) using this battery member is excellent in battery characteristics such as discharge characteristics.

As a second modification, the battery member manufacturing method according to each of the above-described embodiments is such that, after the electrolyte layers 7A and 7B are formed, another electrolyte is formed on the electrolyte layers (first electrolyte layers) 7A and 7B. You may further provide the process of laminating | stacking a layer (2nd electrolyte layer). In this case, since the first electrolyte layer plays a role in favorably forming the interface between the electrode mixture layer and the second electrolyte layer, the first electrolyte layer can also be called an interface forming layer. A secondary battery using a battery member obtained by this manufacturing method includes a positive electrode current collector, a positive electrode mixture layer, a first interface forming layer, an electrolyte layer (second electrolyte layer), a second electrode group as an electrode group. An interface forming layer, a negative electrode mixture layer, and a negative electrode current collector are provided in this order.

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

The interface forming layer may have the same composition as the electrolyte layer in the battery member of each embodiment described above. That is, the manufacturing method according to this modification is a method in which the electrolyte layer is replaced with the interface forming layer in each of the above-described embodiments.

In this manufacturing method, the battery member can be manufactured by disposing the electrolyte layer on the surface on the first interface forming layer side of the positive electrode member or on the surface of the negative electrode member on the second interface forming layer side. . In this embodiment, the electrolyte layer at this time may be one in which the above-described

electrolyte slurries

15A and 15B are formed in a sheet shape. That is, a base material such as a film made of a resin is prepared, and the

electrolyte slurry

15A, 15B is applied on the base material, and then the dispersion medium is volatilized to prepare an electrolyte sheet. And an electrolyte layer can be obtained by peeling a base material from this electrolyte sheet.

In other embodiments, the electrolyte layer in the second modification may have a composition different from that of the electrolyte layer produced from the

electrolyte slurries

15A and 15B. For example, an organic polymer solid electrolyte, an inorganic solid A known electrolyte composition such as an electrolyte may be formed into a sheet shape in advance. In this case, the organic polymer solid electrolyte may be polyethylene oxide or the like, and the inorganic solid electrolyte may 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 Yes, 0 ≦ d <3, where (Ti, Ge) means either Ti or Ge, or both Ti and Ge.), Li ₁₀ GeP ₂ S ₁₂ , Li _9.54 Si _1.74 P _1.44 S _11.7 Cl _0.3 or the like.

Even in the battery member obtained in this way, the positive electrode mixture layer / first interface forming layer interface and the negative electrode mixture layer / second interface forming layer interface are well formed and excellent in adhesion. At the same time, the electrode active material / electrolyte interface is well formed. Furthermore, when the ionic liquid electrolyte is included in the interface forming layer, ionic conduction between the interface forming layer and the electrolyte layer becomes easier. As a result, since the secondary battery using the battery member according to this modification can be said to have an excellent interface between the layers, the secondary battery has excellent battery characteristics.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the following, when expressing the composition of the ionic liquid (ionic liquid electrolytic solution) in which the electrolyte salt is dissolved, “concentration of electrolyte salt (M = mol / L) / type of electrolyte salt / type of ionic liquid” It may be written as

<Test 1>
<Example 1-1>
[Production of positive electrode member]
70 parts by mass of layered lithium / nickel / manganese / cobalt composite oxide (positive electrode active material), 7 parts by mass of acetylene black (conductive agent, product name: HS-100, average particle size 48 nm, manufactured by Denka Corporation), 9 parts by mass of a copolymer solution of vinylidene fluoride and hexafluoropropylene (solid content: 12% by mass) and N-methyl-N-propylpyrrolidinium bis (fluorosulfonyl) imide (Py13-FSI) as an ionic liquid 14 parts by mass of an ionic liquid electrolyte (1.5 M / Li [FSI] / Py13-FSI) in which lithium bis (fluorosulfonyl) imide (Li [FSI]) as a salt is dissolved, and N as a dispersion medium A positive electrode mixture slurry was prepared by dispersing in 250 parts by mass of methyl-2-pyrrolidone (NMP). This positive electrode mixture slurry was applied onto a positive electrode current collector (aluminum foil having a thickness of 20 μm) at a coating amount of 125 g / m ² , heated at 80 ° C. for 12 hours, dried, and pressed, whereby the mixture was obtained. A positive electrode mixture intermediate layer having a density of 2.7 g / cm ³ was formed. This was cut into a width of 30 mm and a length of 45 mm, and then a positive electrode current collecting tab was attached.

Copolymer of vinylidene fluoride as the first structural unit and hexafluoropropylene as the second structural unit (mass ratio of the content of the first structural unit to the content of the second structural unit = 95/5 (Hereinafter also referred to as PVDF-HFP)), 40 parts by mass of SiO ₂ particles (average particle size of 0.1 μm) which are oxide particles not subjected to surface treatment, and NMP300 as a dispersion medium. An electrolyte slurry was prepared by dispersing in mass parts. The obtained electrolyte slurry was applied 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, the positive electrode member provided with a positive electrode collector, a positive mix layer, and an electrolyte layer in this order was obtained. The thickness of the electrolyte layer in the obtained positive electrode member was 15 ± 2 μm.

[Preparation of negative electrode member]
57.4 parts by mass of graphite (negative electrode active material, manufactured by Hitachi Chemical Co., Ltd.), 1.6 parts by mass of acetylene black (conductive agent, product name: HS-100, average particle size 48 nm, manufactured by Denka Co., Ltd.), 7.8 parts by mass of a copolymer solution of vinylidene fluoride and hexafluoropropylene (solid content 12% by mass), and an ionic liquid electrolyte solution (1.5M / Li [FSI] / Py13-FSI) 33.2 in which an electrolyte salt is dissolved The negative electrode mixture slurry was prepared by dispersing the mass part in 250 mass parts of NMP as a dispersion medium. This negative electrode mixture slurry was coated on a negative electrode current collector (copper foil having a thickness of 10 μm) at a coating amount of 60 g / m ² , heated at 80 ° C. for 12 hours and dried to obtain a mixture density of 1. A negative electrode mixture intermediate layer of 8 g / cm ³ was formed. This was cut into a width of 31 mm and a length of 46 mm, and then a negative electrode current collecting tab was attached.

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

[Production of lithium ion secondary battery]
The produced positive electrode member and negative electrode member were laminated so that the respective electrolyte layers were in contact with each other, thereby producing an electrode group. As shown in FIG. 1, this electrode group was housed in a battery exterior body made of an aluminum laminate film. In the battery outer package, the positive electrode current collection tab and the negative electrode current collection tab were taken out to seal the opening of the battery container, thereby producing a lithium ion secondary battery. The aluminum laminate film is a laminate of polyethylene terephthalate (PET) film / aluminum foil / sealant layer (polypropylene, etc.). The designed capacity of the produced lithium ion secondary battery was 20 mAh.

<Example 1-2>
In Example 1-1, a lithium ion secondary was prepared in the same manner as in Example 1-1 except that the polymer content in the electrolyte slurry was changed to 50 parts by mass and the oxide particle content was changed to 50 parts by mass. A battery was produced.

<Example 1-3>
14 mass of ionic liquid electrolyte (1.5 M / Li [FSI] / Py13-FSI) obtained by dissolving Li [FSI] as an electrolyte salt in Py13-FSI which is an ionic liquid in the electrolyte slurry in Example 1-1 A lithium ion secondary battery was produced in the same manner as in Example 1-1, except that further parts were added.

<Example 1-4>
Example 1-3 was the same as Example 1-3 except that the content of the ionic liquid electrolyte (1.5 M / Li [FSI] / Py13-FSI) in the electrolyte slurry was changed to 9 parts by mass. A lithium ion secondary battery was produced by the method.

<Example 1-5>
In Example 1-3, the content of the polymer in the electrolyte slurry was 30 parts by mass, the content of the oxide particles was 20 parts by mass, and the ionic liquid (1.5M / Li [FSI] / Py13-FSI) A lithium ion secondary battery was produced in the same manner as in Example 1-3, except that the content was changed to 50 parts by mass.

<Example 1-6>
[Production of positive electrode member]
(Formation of positive electrode mixture interlayer)
92.5 parts by mass of layered lithium / nickel / manganese / cobalt composite oxide (positive electrode active material) and acetylene black (conductive agent, product name: HS-100, average particle size 48 nm, manufactured by Denka Corporation) 2.5 A positive electrode mixture slurry was prepared by dispersing 5 parts by mass of 5 parts by mass of a copolymer solution of vinylidene fluoride and hexafluoropropylene (solid content: 12% by mass) in 250 parts by mass of NMP as a dispersion medium. This positive electrode mixture slurry was applied onto a positive electrode current collector (aluminum foil having a thickness of 20 μm) at a coating amount of 125 g / m ² , heated at 80 ° C. for 12 hours, dried, and pressed, whereby the mixture was obtained. A positive electrode mixture intermediate layer having a density of 2.7 g / cm ³ was formed. This was cut into a width of 30 mm and a length of 45 mm, and then a positive electrode current collecting tab was attached.

(Synthesis of polymer used for polymer solution)
A polymer having the structural unit represented by the formula (1) was synthesized by converting the counter anion [Cl] ⁻ of poly (diallyldimethylammonium) chloride into [TFSI] ⁻ . First, 100 parts by mass of [P (DADMA)] [Cl] aqueous solution (20% by mass aqueous solution, manufactured by Aldrich) was diluted with 500 parts by mass of distilled water to obtain a diluted polymer solution. Next, 43 parts by mass of Li [TFSI] (manufactured by Kishida Chemical Co., Ltd.) was dissolved in 100 parts by mass of water to prepare a Li [TFSI] aqueous solution. The Li [TFSI] aqueous solution was added dropwise to the diluted solution, and the mixture was stirred for 2 hours to obtain a white precipitate. The precipitate was separated by filtration, washed with 400 parts by mass of distilled water, and then filtered again. Washing and filtration were repeated 5 times. Then, the water | moisture content of the deposit was evaporated by vacuum drying of 105 degreeC, and [P (DADMA)] [TFSI] which is a polymer which has a structural unit represented by Formula (1) was obtained. The viscosity average molecular weight of [P (DADMA)] [TFSI] was 2.11 × 10 ⁶ g · mol ⁻¹ .

The viscosity average molecular weight Mv is determined by measuring the viscosity [η] of the polymer at 25 ° C. using an Ubbelohde viscometer using polymethyl methacrylate (PMMA) as a standard substance, and then [η] = KMv (where, K represents an expansion factor, the value of which depends on temperature, polymer, and solvent properties.

(Preparation and application of polymer solution)
For 24 parts by mass of the obtained polymer ([P (DADMA)] [TFSI]), 18 parts by mass of Li [FSI] as an electrolyte salt and Py13-FSI (manufactured by Kanto Chemical Co., Inc.) as an ionic liquid 58 parts by mass and 72 parts by mass of acetone as a dispersion medium were added and stirred to obtain a polymer solution.

The prepared polymer solution was applied onto the positive electrode mixture intermediate layer with a gap of 150 μm by the doctor blade method. Thereafter, the polymer solution was vacuum-dried at 60 ° C. for 12 hours. Thereby, the polymer represented by Formula (1) was contained in the positive electrode mixture intermediate layer.

Next, an electrolyte slurry having the same composition as in Example 1-1 was prepared, and a positive electrode member including a positive electrode current collector, a positive electrode mixture layer, and an electrolyte layer in this order was prepared by the same method as in Example 1-1. Obtained.

[Preparation of negative electrode member]
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 size 48 nm, manufactured by Denka Co., Ltd.), vinylidene fluoride and hexa A negative electrode mixture slurry was prepared by dispersing 5 parts by mass of a copolymer of fluoropropylene (solid content: 12% by mass) in 250 parts by mass of NMP as a dispersion medium. This negative electrode mixture slurry was coated on a negative electrode current collector (copper foil having a thickness of 10 μm) at a coating amount of 60 g / m ² , heated at 80 ° C. for 12 hours, dried, and pressed to form a mixture. A negative electrode mixture intermediate layer having a density of 1.8 g / cm ³ was formed. This was cut into a width of 31 mm and a length of 46 mm, and then a negative electrode current collecting tab was attached.

Similarly to the positive electrode member described above, a polymer containing [P (DADMA)] [TFSI], which is a polymer having the structural unit represented by the formula (1), was included in the negative electrode mixture intermediate layer. Further, a negative electrode member including a negative electrode current collector, a positive electrode mixture layer, and an electrolyte layer in this order was obtained by the same method as in Example 1-1.

[Production of lithium ion secondary battery]
Using the obtained positive electrode member and negative electrode member, a lithium ion secondary battery was produced in the same manner as in Example 1-1.

<Example 1-7>
A lithium ion secondary battery was produced in the same manner as in Example 1-6 except that in Example 1-6, the ionic liquid contained in the polymer solution was changed to EMI-FSI.

<Example 1-8>
[Production of positive electrode member]
92.5 parts by mass of layered lithium / nickel / manganese / cobalt composite oxide (positive electrode active material) and acetylene black (conductive agent, product name: HS-100, average particle size 48 nm, manufactured by Denka Corporation) 2.5 A positive electrode mixture slurry was prepared by dispersing 5 parts by mass of 5 parts by mass of a copolymer solution of vinylidene fluoride and hexafluoropropylene (solid content: 12% by mass) in 250 parts by mass of NMP as a dispersion medium. This positive electrode mixture slurry was applied onto a positive electrode current collector (aluminum foil having a thickness of 20 μm) at a coating amount of 125 g / m ² , heated at 80 ° C. for 12 hours, dried, and pressed, whereby the mixture was obtained. A positive electrode mixture intermediate layer having a density of 2.7 g / cm ³ was formed. This was cut into a width of 30 mm and a length of 45 mm, and then a positive electrode current collecting tab was attached.

30 parts by mass of PVDF-HFP, 20 parts by mass of untreated SiO ₂ particles (average particle size 0.1 μm), and ionic liquid electrolyte (1.5 M / Li [FSI] / Py13-FSI) An electrolyte slurry was prepared by dispersing 50 parts by mass in 300 parts by mass of NMP as a dispersion medium. The obtained electrolyte slurry was applied 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, the positive electrode member provided with a positive electrode collector, a positive mix layer, and an electrolyte layer in this order was obtained. The thickness of the electrolyte layer in the obtained positive electrode member was 15 ± 2 μm.

<Example 1-9>
A lithium ion secondary battery was fabricated in the same manner as in Example 1-8, except that the electrolyte slurry ionic liquid electrolyte was changed to 1.5 M / Li [FSI] / EMI-FSI in Example 1-8. did.

<Confirmation of adhesion between electrode mixture layer and electrolyte layer>
The positive electrode member and the negative electrode member (battery member) according to Example 1-8 were each cut by ion milling (E-3500, manufactured by Hitachi High-Technologies Corporation) to expose the cross section of the battery member. The cross-section was observed with a scanning electron microscope (SEM, JSM-6010LA, manufactured by JEOL Ltd.), and it was confirmed by visual observation that there was no peeled portion between the electrode mixture layer and the electrolyte layer. In addition, it was also confirmed whether there were no voids around the electrode active material (positive electrode active material and negative electrode active material). FIG. 6 shows an SEM image obtained by observing a cross section of the battery member according to Example 1-8. 6A shows a cross section of the positive electrode member, and FIG. 6B shows a cross section of the negative electrode member.

As a result, as shown in FIG. 6, in the lithium ion secondary battery of Example 1-8, there was no part where the electrode mixture layer and the electrolyte layer were separated, and the electrode mixture layer and the electrolyte layer It was judged that the adhesion between the two was good. Moreover, since no void was found around the electrode active material, it was determined that the interface between the electrode active material and the electrolyte was well formed. Also in Examples 1-1 to 1-7 and Example 1-9, the cross section is similarly observed, whereby the adhesion between the electrode mixture layer and the electrolyte layer is good, and the electrode It was confirmed that the interface between the active material and the electrolyte was well formed.

<Test 2 (reference)>
<Example 2-1>
[Production of positive electrode member]
92.5 parts by mass of layered lithium / nickel / manganese / cobalt composite oxide (positive electrode active material) and acetylene black (conductive agent, product name: HS-100, average particle size 48 nm, manufactured by Denka Corporation) 2.5 A positive electrode mixture prepared by dispersing 5 parts by mass of a copolymer part (solid content: 12% by mass) of vinylidene fluoride and hexafluoropropylene in an appropriate amount of N-methyl-2-pyrrolidone (NMP) as a dispersion medium. A slurry was prepared. This positive electrode mixture slurry was applied onto a positive electrode current collector (aluminum foil having a thickness of 20 μm) at a coating amount of 125 g / m ² , heated at 80 ° C. for 12 hours, dried, and pressed, whereby the mixture was obtained. A positive electrode mixture intermediate layer having a density of 2.7 g / cm ³ was formed. This was cut into a width of 30 mm and a length of 45 mm, and then a positive electrode current collecting tab was attached.

25 parts by mass of PVDF-HFP and surface-treated SiO ₂ particles (specific surface area: 50 m ² / g, surface treatment: hexamethyldisilazane, average primary particle size: 40 nm, product name: AEROSIL RX50, Nippon Aerosil Co., Ltd. An electrolyte slurry was prepared by dispersing 12 parts by mass of the company) and 63 parts by mass of an ionic liquid electrolyte (1.0 M / Li [FSI] / EMI-FSI) in an appropriate amount of NMP as a dispersion medium. The obtained electrolyte slurry was applied 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, the positive electrode member provided with a positive electrode collector, a positive mix layer, and an electrolyte layer in this order was obtained. The thickness of the electrolyte layer in the obtained positive electrode member was 15 ± 2 μm.

[Preparation of negative electrode member]
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 size 48 nm, manufactured by Denka Co., Ltd.), vinylidene fluoride and hexa A negative electrode mixture slurry was prepared by dispersing 5 parts by mass of a copolymer solution of fluoropropylene (solid content: 12% by mass) in an appropriate amount of NMP as a dispersion medium. This negative electrode mixture slurry was coated on a current collector (copper foil having a thickness of 10 μm) at a coating amount of 60 g / m ² , heated at 80 ° C. for 12 hours, dried, and pressed to obtain a mixture density. A negative electrode mixture intermediate layer of 1.8 g / cm ³ was formed. This was cut into a width of 31 mm and a length of 46 mm, and then a negative electrode current collecting tab was attached.

By applying the above-described electrolyte slurry on the surface of the negative electrode mixture intermediate layer opposite to the negative electrode current collector, the dispersion medium is volatilized to form an electrolyte layer by the same method as the positive electrode member manufacturing method. It was. Thereby, the negative electrode member provided with the negative electrode current collector, the negative electrode mixture layer, and the electrolyte layer in this order was obtained. The thickness of the electrolyte layer in the obtained negative electrode member was 15 ± 2 μm.

<Example 2-2 to Example 2-3>
A lithium ion secondary battery was produced in the same manner as in Example 2-1, except that the electrolyte salt concentration was changed to that shown in Table 1 in the preparation of the electrolyte slurry.

<Example 2-4>
In the preparation of the electrolyte slurry, lithium ion secondary was prepared in the same manner as in Example 2-1, except that PVDF-HFP was changed to 15 parts by mass, SiO ₂ particles to 29 parts by mass, and ionic liquid electrolyte to 56 parts by mass. A battery was produced.

<Reference Example 2-1>
Example 2 except that the oxide particles were changed to non-surface-treated SiO ₂ particles (specific surface area: 50 m ² / g, average primary particle size: 40 nm, product name: AEROSIL OX50, manufactured by Nippon Aerosil Co., Ltd.) A lithium ion secondary battery was produced in the same manner as in -1.

Regarding the lithium ion secondary batteries of Example 2-1 to Example 2-4 and Reference Example 2-1, the adhesion between the electrode mixture layer and the electrolyte layer was confirmed by the same method as in Test 1. In the lithium ion secondary battery, it was confirmed that the adhesion between the electrode mixture layer and the electrolyte layer was good and that the interface between the electrode active material and the electrolyte was well formed.

<Evaluation of discharge characteristics>
0.1 C constant current charging was performed up to an upper limit voltage of 4.2 V. Thereafter, constant current discharge with a final voltage of 2.7 V was performed at a current value of 0.1 C, and the capacity at the time of discharge was defined as the discharge capacity at a current value of 0.1 C. Next, after performing constant current charging at 0.1 C up to an upper limit voltage of 4.2 V, constant current discharging at a final voltage of 2.7 V is performed at a current value of 0.5 C, and the capacity at the time of discharge is set to a current value of 0.2 V. The discharge capacity was 5C. The discharge capacity retention ratio (0.5 C / 0.1 C) was calculated by the following formula. The results are shown in Table 1.
Discharge capacity retention rate (%) = (discharge capacity at current value 0.5 C / discharge capacity at current value 0.1 C) × 100

DESCRIPTION OF SYMBOLS 1 ... Secondary battery, 6 ... Positive electrode, 7 ... Electrolyte layer, 8 ... Negative electrode, 9 ... Positive electrode collector, 10 ... Positive electrode mixture layer, 11 ... Negative electrode collector, 12 ... Negative electrode mixture layer, 13 ...

Collection

14A, 14B, 14C ... electrode mixture intermediate layer, 15A, 15B ... slurry (electrolyte slurry), 16 ... oxide particles, 17 ... polymer, 18A, 18B ... electrode mixture layer, 19A, 19B ... secondary Battery member for battery, 20 ... polymer solution.

Claims

Forming an electrode mixture intermediate layer containing an electrode active material on one surface of the current collector;
Applying a slurry containing oxide particles and a polymer on the surface of the electrode mixture intermediate layer opposite to the current collector,
At least one of the said electrode mixture intermediate | middle layer and the said slurry contains an ionic liquid and electrolyte salt, The manufacturing method of the battery member for secondary batteries.
The manufacturing method according to claim 1, wherein one of the electrode mixture intermediate layer and the slurry contains the ionic liquid and the electrolyte salt.
The manufacturing method according to claim 2, wherein the slurry contains the ionic liquid and the electrolyte salt.
The manufacturing method according to claim 1, wherein both the electrode mixture intermediate layer and the slurry contain the ionic liquid and the electrolyte salt.
The production method according to any one of claims 1 to 4, wherein the oxide particles have a hydrophobic surface.
The manufacturing method according to claim 5, wherein the oxide particles are surface-treated with a silicon-containing compound.
The production method according to claim 6, wherein the silicon-containing compound is at least one selected from the group consisting of halogen-containing alkylsilanes, alkoxysilanes, epoxy group-containing silanes, amino group-containing silanes, silazanes, and siloxanes.
The production method according to any one of claims 1 to 7, wherein the polymer 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. The manufacturing method according to claim 8.
The production method according to any one of claims 1 to 9, wherein the concentration of the electrolyte salt per unit volume of the ionic liquid is 0.3 to 3.0 mol / L.
The method further comprises the step of infiltrating a solution containing a polymer having a structural unit represented by the following formula (1) into the electrode mixture intermediate layer before the step of applying the slurry. The manufacturing method as described in any one of these.

[In formula (1), X − represents a counter anion. ]