CN108735972B - Method for manufacturing battery member for secondary battery - Google Patents

Abstract

The present invention provides a method for manufacturing a battery member for a secondary battery, which comprises: the method for manufacturing the electrode material mixture layer includes a step of forming an electrode material mixture intermediate layer containing an electrode active material on a main surface of a current collector, and a step of applying a slurry containing oxide particles and a polymer on a surface of the electrode material mixture intermediate layer on a side opposite to the current collector, wherein at least one of the electrode material mixture intermediate layer and the slurry contains an ionic liquid and an electrolyte salt.

Description

Method for manufacturing battery member for secondary battery

Technical Field

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

Background

In recent years, due to the spread of portable electronic devices, electric vehicles, and the like, high-performance secondary batteries have been required. Among them, lithium secondary batteries have been attracting attention as power sources for batteries for electric vehicles, batteries for electric power storage, and the like because of their high energy density. Specifically, lithium secondary batteries, which are batteries for electric vehicles, are used in electric vehicles such as zero-emission electric vehicles in which an engine is not mounted, hybrid electric vehicles in which both an engine and a secondary battery are mounted, and plug-in hybrid electric vehicles in which a power system is directly charged. In addition, lithium secondary batteries, which are batteries for power storage, are also used in stationary power storage systems and the like that supply power stored in advance when an emergency occurs in which a power system is shut down.

In order to be used for such a wide range of applications, lithium secondary batteries having a higher energy density are required, and development thereof has been made. In particular, lithium secondary batteries for electric vehicles are required to have high safety in addition to high input/output characteristics and high energy density, and therefore, higher-level technologies for ensuring safety are required.

As a method for improving the safety of a lithium secondary battery, a method of changing an electrolyte to a solid electrolyte, and the like are known (for example, japanese patent laid-open No. 2004-107641).

Disclosure of Invention

However, in the case of manufacturing a lithium secondary battery using a solid electrolyte, unlike a secondary battery using an electrolytic solution, since the contact surface between the electrode mixture layer and the electrolyte layer is a solid/solid interface and the contact surface between the electrode active material in the electrode mixture layer and the electrolyte is also a solid/solid interface, it is difficult to make these interfaces adhere well. If these interfaces do not adhere well to the secondary battery, the internal resistance of the secondary battery may increase, resulting in a decrease in battery characteristics. Therefore, a method capable of forming an electrode mixture layer/electrolyte layer interface and an electrode active material/electrolyte interface in the electrode mixture layer in a good and simple manner is required.

The purpose of the present invention is to provide a method for producing a battery member for a secondary battery, wherein the interface between an electrode active material and an electrolyte in an electrode mixture layer can be formed well, and the interlayer adhesion between the electrode mixture layer and the electrolyte layer is excellent.

The present invention provides a method for manufacturing a battery member for a secondary battery, comprising: the method for manufacturing a collector includes a step of forming an electrode mixture intermediate layer containing an electrode active material on a main surface of a collector, and a step of applying a slurry containing oxide particles and a polymer on a surface of the electrode mixture intermediate layer opposite to the collector, wherein 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 layer and the slurry may contain an ionic liquid and an electrolyte salt. Both the electrode mixture intermediate layer and the slurry may contain an ionic liquid and an electrolyte salt.

The production method of the present invention may further comprise, before the step of applying the electrolyte slurry, a step of allowing a solution containing a polymer having a structural unit represented by the following formula (1) to permeate into the electrode material mixture intermediate layer.

[ in the formula (1), X ^- Represents a counter anion.]

According to the present invention, it is possible to provide a method for producing a battery member for a secondary battery, in which an electrode active material/electrolyte interface in an electrode mixture layer can be formed well, and further, the interlayer adhesion between the electrode mixture layer and an electrolyte layer is excellent.

Drawings

Fig. 1 is a perspective view showing a secondary battery according to an embodiment.

Fig. 2 is an exploded perspective view illustrating an embodiment of an electrode assembly of the secondary battery shown in fig. 1.

Fig. 3 is a schematic cross-sectional view illustrating a method for manufacturing a battery member for a secondary battery according to embodiment 1.

Fig. 4 is a schematic cross-sectional view illustrating a method for manufacturing a battery member for a secondary battery according to embodiment 2.

Fig. 5 is an exploded perspective view showing one embodiment of an electrode group of a secondary battery according to a modification.

Fig. 6 is an SEM image obtained by observing a cross section of the battery member for a secondary battery according to example 8.

Description of the symbols

1: a secondary battery; 6: a positive electrode; 7: an electrolyte layer; 8: a negative electrode; 9: a positive electrode current collector; 10: a positive electrode mixture layer; 11: a negative electrode current collector; 12: a negative electrode mixture layer; 13: a current collector; 14A, 14B, 14C, 14D: an electrode mix intermediate layer; 15A, 15B: a slurry (electrolyte slurry); 16: oxide particles; 17: polymer, 18A, 18B: an electrode mixture layer; 19A, 19B: a battery member for a secondary battery; 20: a polymer solution.

Detailed Description

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

The numerical values and ranges thereof in this specification do not limit the invention. The numerical range expressed by the term "to" in the present specification means a range including numerical values before and after the term "to" as a minimum value and a maximum value, respectively. In the numerical ranges recited in the present specification, the upper limit or the lower limit recited in one numerical range may be replaced with the upper limit or the lower limit recited in another numerical range. In the numerical ranges described in the present specification, the upper limit or the lower limit of the numerical range may be replaced with the values shown in the examples.

In this specification, the following abbreviations may be used.

[Py13] ⁺ : N-methyl-N-propylpyrrolidine

Cation(s)

[FSI] ^- : bis (fluorosulfonyl) imide anions

[TFSI] ^- : bis (trifluoromethanesulfonyl) imide anion

[f3C] ^- : carbon ion of tris (fluorosulfonyl) anion

[BOB] ^- : bis (oxalato) borate anion

[ P (DADMA) ] [ Cl ]: poly diallyl dimethyl ammonium chloride

[ P (DADMA) ] [ TFSI ]: poly (diallyldimethylammonium) 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 including a positive electrode, a negative electrode, and an electrolyte layer, and a bag-shaped battery exterior 3 accommodating the electrode group 2. The positive electrode and the negative electrode are respectively provided with a positive electrode current collecting tab 4 and a negative electrode current collecting tab 5. A positive electrode collector tab 4 and a negative electrode collector tab 5 protrude from the inside to the outside of the battery outer case 3 so that the positive electrode and the negative electrode can be electrically connected to the outside of the secondary battery 1, respectively.

The battery exterior body 3 may be formed of a laminate film, for example. The laminate film may be, for example, a laminate film in which a resin film such as a polyethylene terephthalate (PET) film, a metal foil such as aluminum, copper, stainless steel, or the like, and a sealing layer such as polypropylene are sequentially laminated.

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

In one embodiment, the electrode group 2A may be regarded as including a cell member (positive electrode member) for the 1 st secondary battery, which includes the positive electrode current collector 9, the positive electrode mixture layer 10, and the electrolyte layer 7 in this order. Similarly, the electrode group 2A may be regarded as including a cell member for the 2 nd secondary battery (negative electrode member) including the negative electrode current collector 11, the negative electrode mixture layer 12, and the electrolyte layer 7 in this order. The method for producing a battery member for a secondary battery (hereinafter, also 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.

[ embodiment 1 ]

Fig. 3 is a schematic cross-sectional view illustrating a method for manufacturing a battery member for a secondary battery according to embodiment 1. In this manufacturing method, first, as shown in fig. 3a, an electrode mixture intermediate layer 14A (positive electrode mixture intermediate layer or negative electrode mixture intermediate layer) containing an electrode active material is formed on a main surface 13a of a current collector 13 (positive electrode current collector 9 or negative electrode current collector 11) (electrode mixture intermediate layer forming step).

In one embodiment, the method of forming the electrode material mixture intermediate layer 14A on the main surface 13a of the current collector 13 in the electrode material mixture intermediate layer forming step is a method of applying an electrode material mixture slurry on the main surface 13a of the current collector 13. The electrode mixture slurry is a slurry (positive electrode mixture slurry or negative electrode mixture slurry) obtained by dispersing the materials contained in the positive electrode mixture layer 10 or the negative electrode mixture layer 12 in a dispersion medium. The electrode mixture slurry of the present 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 a 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. The positive electrode current collector 9 is preferably aluminum or an alloy thereof because it is lightweight and has a high weight energy density. 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 a 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. Negative electrode current collector 11 is preferably aluminum or an alloy thereof because it is lightweight and has a high weight energy density. From the viewpoint of ease of processing a thin film and cost, negative electrode collector 11 is preferably copper. The thickness of the negative electrode collector 11 may be 10 μm or more and 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. The lithium transition metal oxide may be one obtained by substituting a part of transition metals such as Mn, ni, and Co contained in lithium manganate, lithium nickelate, and lithium cobaltate with one or two or more kinds of other transition metals, or metal elements (typical elements) such as Mg and Al. That is, the lithium transition metal oxide may be LiM ¹ O ₂ Or LiM ¹ O ₄ (M ¹ Including at least one transition metal). Specifically, the lithium transition metal oxide may be Li (Co) _1/3 Ni _1/3 Mn _1/3 )O ₂ 、LiNi _1/2 Mn _1/2 O ₂ 、LiNi _1/2 Mn _3/2 O ₄ And the like.

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)

[ formula (2) wherein M ² Is at least one selected from the group consisting of Al, mn, mg and Ca, and a, b, c, d and e are numbers satisfying 0.2 ≦ a ≦ 1.2, 0.5 ≦ b ≦ 0.9, 0.1 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.2, -0.2 ≦ e ≦ 0.2, and b + c + d =1, respectively.]

The lithium transition metal phosphate may be LiFePO ₄ 、LiMnPO ₄ 、LiMn _x M ³ _1-x PO ₄ (0.3≦x≦1、M ³ Is at least one element selected from the group consisting of Fe, ni, co, ti, cu, zn, mg, and Zr), and the like.

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

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 coarse particles having a particle diameter equal to or larger than the thickness of the positive electrode mixture layer 10 are present in the positive electrode active material, the coarse particles are removed in advance by sieving classification, air flow classification, or the like, and the positive electrode active material having a particle diameter equal to or smaller than the thickness of the positive electrode mixture layer 10 is selected.

The average particle diameter of the positive electrode active material is preferably 0.1 μm or more, and more preferably 1 μm or more. The average particle diameter of the positive electrode active material is preferably 30 μm or less, and more preferably 25 μm or less. The average particle diameter of the positive electrode active material is a particle diameter (D) at which the ratio of the volume of the positive electrode active material to the total volume of the positive electrode active material (volume fraction) is 50% ₅₀ ). Average particle diameter (D) of positive electrode active material ₅₀ ) Obtained as follows: a suspension obtained by suspending the positive electrode active material in water is measured by a laser light scattering method using a laser light scattering type particle size measuring apparatus (e.g., microtrac).

The content of the positive electrode active material may be 70% by mass or more, 80% by mass or more, or 90% by mass or more, and may be 99% by mass or less, based on the total amount of nonvolatile components (components obtained by removing the dispersion medium from the positive electrode mixture slurry) in the positive electrode mixture slurry. Thus, the content of the positive electrode active material in the obtained positive electrode mixture layer was the same as the above content.

In the case where the battery member is an anode member, the electrode active material is an anode 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 metallic lithium and lithium titanate (Li) ₄ Ti ₅ O ₁₂ ) Lithium alloys or other metal compounds, carbon materials, metal complexes, and organic polymer compounds. The negative electrode active material may be a single one of them or a mixture of two or more of them. As the carbon material, a carbon material, examples thereof include natural Graphite (e.g., flake Graphite), graphite (Graphite) such as artificial Graphite, amorphous carbon, carbon fiber, acetylene black, ketjen black, channel black, furnace black, and the like,Lamp black, thermal black, and the like. The negative electrode active material may be silicon, tin, or a compound containing these elements (oxide, nitride, alloy with other metals) from the viewpoint of obtaining a larger theoretical capacity (for example, 500 to 1500 Ah/kg).

The average particle diameter (D) of the negative electrode active material is such that a well-balanced negative electrode is obtained that improves the holding ability of the electrolyte salt while suppressing an increase in irreversible capacity associated with a decrease in particle diameter ₅₀ ) It is preferably not less than 1 μm, more preferably not less than 5 μm, still more preferably not less than 10 μm, and furthermore preferably not less than 50 μm, more preferably not less than 40 μm, still more preferably not less than 30 μm. Average particle diameter (D) of negative electrode active material ₅₀ ) By the average particle diameter (D) of the positive electrode active material ₅₀ ) The same method is used for determination.

The content of the negative electrode active material may be 60% by mass or more, 65% by mass or more, or 70% by mass or more, based on the total amount of nonvolatile components (components after removing the dispersion medium from the negative electrode mixture slurry) in the negative electrode mixture slurry, or may be 99% by mass or less, 95% by mass or less, or 90% by mass or less. Thus, the content of the negative electrode active material in the obtained negative electrode mixture layer is the same as the above content.

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

The electrode mixture paste 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 14A further containing these materials is formed.

In one embodiment, the electrode mix slurry contains an ionic liquid and an electrolyte salt. In this case, the electrode mixture slurry may contain the ionic liquid and the electrolyte salt in the form of an "ionic liquid electrolyte solution" in which the electrolyte salt is dissolved in the ionic liquid. The electrode mixture slurry may not contain the ionic liquid and the electrolyte salt, but in this case, a slurry (electrolyte slurry) described later contains the ionic liquid and the electrolyte salt. That is, at least one of the electrode mixture paste and the electrolyte paste contains an ionic liquid and an electrolyte salt.

The ionic liquid contains the following anionic component and cationic component. In this specification, the ionic liquid is a substance that is in a liquid state at a temperature of-20 ℃ or higher.

The anionic component of the ionic liquid is not particularly limited, and may be Cl ^- 、Br ^- 、I ^- Anions of isohalogens, BF ₄ ^- 、N(SO ₂ F) ₂ ^- Iso inorganic anion, 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 ^- Organic anions and the like. The anion component of the ionic liquid preferably contains at least one of the anion components represented by the following formula (3).

N(SO ₂ C _m F _2m+1 )(SO ₂ C _n F _2n+1 ) ^- (3)

[ in the formula (3), m and n each independently represent an integer of 0 to 5. m and n may be the same or different from each other, and are preferably the same. ]

The anion component represented by the formula (3) is, for example, N (SO) ₂ C ₄ F ₉ ) ₂ ^- 、N(SO ₂ F) ₂ ^- 、N(SO ₂ CF ₃ ) ₂ ^- And N (SO) ₂ C ₂ F ₅ ) ₂ ^- . From the viewpoint of further improving the ion conductivity and also further improving the charge and discharge characteristics at a relatively low viscosity, the anionic component of the ionic liquid more preferably contains a compound selected from the group consisting of N (SO) ₂ C ₄ F ₉ ) ₂ ^- 、CF ₃ SO ₂ O ^- 、N(SO ₂ F) ₂ ^- 、N(SO ₂ CF ₃ ) ₂ ^- And N (SO) ₂ C ₂ F ₅ ) ₂ ^- At least one member of the group consisting of, more preferably, N (SO) ₂ F) ₂ ^- 。

The cation component of the ionic liquid is preferably selected from the group consisting of linear quaternary phosphonium salts

Cation, piperidine

Cation, pyrrolidine

Cation, pyridine

Cation and imidazole

At least one member of the group consisting of cations.

Chain season

The cation is, for example, a compound represented by the following formula (4).

[ in the formula (4), R ¹ ～R ⁴ Each independently represents a C1-20 chain alkyl group or R-O- (CH) ₂ ) _n Chain alkoxyalkyl group represented by (R represents a methyl group)Or an ethyl group, n represents an integer of 1 to 4), and X represents a nitrogen atom or a phosphorus atom. R is ¹ ～R ⁴ The number of carbon atoms of the alkyl group is preferably 1 to 20, more preferably 1 to 10, and still more preferably 1 to 5.]

Piperidine derivatives

The cation is, for example, a six-membered cyclic compound containing nitrogen represented by the following formula (5).

[ in the formula (5), R ⁵ And R ⁶ Each independently represents an alkyl group having 1 to 20 carbon atoms or R-O- (CH) ₂ ) _n Alkoxyalkyl groups represented by the formula (R represents a methyl group or an ethyl group, and n represents an integer of 1 to 4). R ⁵ And R ⁶ The number of carbon atoms of the alkyl group is preferably 1 to 20, more preferably 1 to 10, and still more preferably 1 to 5.]

Pyrrolidine as a therapeutic agent

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

[ in the formula (6), R ⁷ And R ⁸ Each independently represents an alkyl group having 1 to 20 carbon atoms or R-O- (CH) ₂ ) _n Alkoxyalkyl group (R represents a methyl group or an ethyl group, and n represents an integer of 1 to 4). R ⁷ And R ⁸ The number of carbon atoms of the alkyl group is preferably 1 to 20, more preferably 1 to 10, and still more preferably 1 to 5.]

Pyridine compound

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

[ in the formula (7), R ⁹ ～R ¹³ Each independently represents an alkyl group having 1 to 20 carbon atoms, R-O- (CH) ₂ ) _n An alkoxyalkyl group represented by the formula (R represents a methyl group or an ethyl group, and n represents an integer of 1 to 4), or a hydrogen atom. R ⁹ ～R ¹³ The number of carbon atoms of the alkyl group is preferably 1 to 20, more preferably 1 to 10, and still more preferably 1 to 5.]

Imidazole

The cation is, for example, a compound represented by the following formula (8).

[ in the formula (8), R ¹⁴ ～R ¹⁸ Each independently represents an alkyl group having 1 to 20 carbon atoms, R-O- (CH) ₂ ) _n An alkoxyalkyl group represented by the formula (R represents a methyl group or an ethyl group, and n represents an integer of 1 to 4), or a hydrogen atom. R is ¹⁴ ～R ¹⁸ The number of carbon atoms of the alkyl group 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 lithium salts, sodium salts, calcium salts, and magnesium salts.

The anion component of the electrolyte salt may be a halide ion (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 N (SO) ₂ F) ₂ ^- 、N(SO ₂ CF ₃ ) ₂ ^- An anion component represented by the above formula (3), PF ₆ ^- 、BF ₄ ^- 、B(O ₂ C ₂ O ₂ ) ₂ ^- Or ClO ₄ ^- 。

The lithium salt may be selected from the group consisting of LiPF ₆ 、LiBF ₄ 、Li[FSI]、Li[TFSI]、Li[f3C]、Li[BOB]、LiClO ₄ 、LiBF ₃ (CF ₃ )、LiBF ₃ (C ₂ F ₅ )、LiBF ₃ (C ₃ F ₇ )、LiBF ₃ (C ₄ F ₉ )、LiC(SO ₂ CF ₃ ) ₃ 、LiCF ₃ SO ₂ O、LiCF ₃ COO and LiRCOO (R is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group).

The sodium salt may be selected from NaPF ₆ 、NaBF ₄ 、Na[FSI]、Na[TFSI]、Na[f3C]、Na[BOB]、NaClO ₄ 、NaBF ₃ (CF ₃ )、NaBF ₃ (C ₂ F ₅ )、NaBF ₃ (C ₃ F ₇ )、NaBF ₃ (C ₄ F ₉ )、NaC(SO ₂ CF ₃ ) ₃ 、NaCF ₃ SO ₂ O、NaCF ₃ COO and NaRCOO (R is alkyl group having 1 to 4 carbon atoms, phenyl group or naphthyl group).

The calcium salt may be selected from 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, a phenyl group, or a naphthyl group).

The magnesium salt may be selected from Mg (PF) ₆ ) ₂ 、Mg(BF ₄ ) ₂ 、Mg[FSI] ₂ 、Mg[TFSI] ₂ 、Mg[f3C] ₂ 、Mg[BOB] ₂ 、Mg(ClO ₄ ) ₂ 、Mg[BF ₃ (CF ₃ )] ₂ 、Mg[BF ₃ (C ₂ F ₅ )] ₂ 、Mg[BF ₃ (C ₃ F ₇ )] ₂ 、Mg[BF ₃ (C ₄ F ₉ )] ₂ 、Mg[C(SO ₂ CF ₃ ) ₃ ] ₂ 、Mg(CF ₃ SO ₃ ) ₂ 、Mg(CF ₃ COO) ₂ And Mg (RCOO) ₂ (R is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group).

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

In the case where the electrode mixture slurry contains an ionic liquid and an electrolyte salt in the form of an ionic liquid electrolyte, the salt concentration of the electrolyte salt per unit volume of the ionic liquid in the ionic liquid electrolyte may be 0.3mol/L or more, 0.5mol/L or more, or 1.0mol/L or more, and may be 3.0mol/L or less, 2.7mol/L or less, or 2.5mol/L or less.

In the case where the electrode mixture paste contains the ionic liquid electrolyte, the content of the ionic liquid electrolyte is preferably not less than 3% by mass, more preferably not less than 5% by mass, and still more preferably not less than 10% by mass, based on the total amount of nonvolatile components in the electrode mixture paste, from the viewpoint of improving the ionic conductivity of the electrode mixture layer, and is preferably not more than 30% by mass, more preferably not more than 25% by mass, and still more preferably not more than 20% by mass, from the viewpoint of improving the strength of the electrode mixture layer.

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 of the above carbon materials. The content of the conductive agent may be 1 to 70% by mass based on the total amount of nonvolatile components in the electrode mixture paste. Thus, the content of the conductive agent in the obtained electrode material mixture layer was the same as the above content.

The binder is not particularly limited, and may be: a polymer containing at least one monomer unit selected from the group consisting of tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate and methyl methacrylate, a rubber such as styrene-butadiene rubber, isoprene rubber and acrylic rubber, and the like. 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 amount of nonvolatile components in the electrode mixture slurry. Thus, the binder content in the obtained electrode material mixture layer was the same as the above content.

In the electrode mixture intermediate layer forming step, examples of a method for applying the electrode mixture slurry include a method of applying the electrode mixture slurry using an applicator, a method of applying the electrode mixture slurry by spraying, and the like. By these methods, the electrode mixture slurry is applied to the main surface 13a of the current collector 13. As a result, as shown in fig. 3 (a), the electrode material mixture intermediate layer 14A is formed on the main surface 13a of the current collector 13.

In the electrode mixture intermediate layer forming step, the dispersion medium in the slurry may be volatilized after the electrode mixture slurry is applied. That is, the "electrode material mixture intermediate layer" in the present specification includes a layer formed of the electrode material mixture paste and a layer formed by volatilizing a part or all of the dispersion medium from the electrode material mixture paste. The method for 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 with heating, or the like. In the method of reducing the pressure, the pressure may be reduced to a vacuum state. The temperature for drying may be 50 to 150 ℃ and the heating time may be varied depending on the temperature so long as the dispersion medium is sufficiently volatilized, and may be, for example, 1 minute to 48 hours.

After the electrode mixture intermediate layer forming step, as shown in fig. 3 (b), a slurry 15A containing oxide particles 16, a polymer 17, and a dispersion medium is applied to a surface 14A of the electrode mixture intermediate layer 14A on the side opposite to the current collector 13. 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, particles of an inorganic oxide. The inorganic oxide may be, for example, an inorganic oxide containing Li, mg, al, si, ca, ti, zr, la, na, K, ba, sr, V, nb, B, ge, or the like as a constituent element. The oxide particles 16 are preferably 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 At least one particle of the group consisting of particles. Since the oxide particles 16 have polarity, the dissociation of the electrolyte in the electrolyte layer can be promoted, and the battery characteristics can be improved.

The oxide particles 16 may be an oxide of a rare earth metal. Specifically, the oxide particles 16 may be scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, or the like.

The oxide particles 16 may have a hydrophobic surface. The oxide particles generally have hydroxyl groups on the surface thereof, and tend to exhibit hydrophilicity. The oxide particles having a hydrophobic surface have a reduced number of hydroxyl groups on the surface as compared with oxide particles not having a hydrophobic surface. Therefore, when the oxide particles having a hydrophobic surface are used, if an ionic liquid is contained in the electrolyte slurry (for example, the anionic component has N (SO) ₂ F) ₂ ^- 、N(SO ₂ CF ₃ ) ₂ ^- Etc.), since the ionic liquid is hydrophobic, it is predicted that the affinity of the oxide particles with the ionic liquid is improved. Therefore, the liquid retention of the ionic liquid in the electrolyte layer 7 is further improved, and as a result, the ionic conductivity of the electrolyte layer 7 is considered to be improved.

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

The oxide particles 16 may be surface-treated with a silicon-containing compound. That is, the oxide particles 16 may be particles in which silicon atoms of the silicon-containing compound are bonded to the surfaces of the oxide particles through oxygen atoms. The silicon-containing compound is preferably at least one selected from the group consisting of an alkoxysilane, an epoxy-containing silane, an amino-containing silane, a silazane, and a siloxane.

The alkoxysilane may be methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxydiphenylsilane, n-propyltrimethoxysilane, hexyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, n-propyltriethoxysilane, etc.

The epoxy-containing silane may be 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, etc.

The amino-containing silane may be N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, etc.

The silazane may be hexamethyldisilazane or the like. The siloxane can be dimethyl silicone oil, etc. They may have a reactive functional group (for example, a carboxyl group or the like) at one or both ends thereof.

The oxide particles having a hydrophobic surface (surface-treated oxide particles) may be particles produced by a known method or may be commercially available.

In general, the oxide particles 16 may include primary particles (particles not constituting secondary particles) in which individual particles are integrally formed, and secondary particles formed by aggregating a plurality of primary particles, as judged from the apparent geometric form.

The specific surface area of the oxide particles 16 may be 2 to 500m ² A ratio of 2 to 400 m/g ² /g、5～100m ² /g、10～80m ² Per g, or 15 to 60m ² (iv) g. If the specific surface area is 2 to 500m ² In terms of the specific volume,/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 2m or more ² A ratio of/g, greater than or equal to 5m ² A ratio of/g, greater than or equal to 10m ² A number of grams of more than or equal to 15m ² A,/g, or greater than or equal to 50m ² A value of,/g, may be 500m or less ² (ii) g, less than or equal to 400m ² A ratio of/g, less than or equal to 300m ² (ii) g, less than or equal to 200m ² A ratio of/g to 100m or less ² A ratio of 90m or less per gram ² A ratio of/g, less than or equal to 80m ² Per g, or less than or equal to 60m ² (ii) in terms of/g. The specific surface area of the oxide particles 16 is the specific surface area of the entire oxide particles including the primary particles and the secondary particles, and can be measured by the BET method.

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

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

The content of the oxide particles 16 is preferably not less than 5% by mass, more preferably not less than 10% by mass, further preferably not less than 15% by mass, particularly preferably not less than 20% by mass, and further preferably not less than 60% by mass, more preferably not less than 50% by mass, further preferably not more than 40% by mass, based on the total amount of nonvolatile components (components after removing the dispersion medium from the electrolyte slurry) in the electrolyte slurry 15A. Thus, the content of the oxide particles 16 in the obtained electrolyte layer becomes the same content as the above content.

The polymer 17 preferably has the 1 st structural unit selected from the group consisting of tetrafluoroethylene and vinylidene fluoride.

The polymer 17 is preferably one or two or more polymers, and the constitutional unit constituting the one or two or more polymers may contain the 1 st constitutional unit and the 2 nd constitutional unit selected from the group consisting of hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate, and methyl methacrylate. That is, the 1 st structural unit and the 2 nd structural unit may be contained in one polymer to constitute a copolymer, or may be contained in different polymers to constitute at least two polymers of a 1 st polymer having the 1 st structural unit and a 2 nd polymer having the 2 nd structural unit.

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

The content of the polymer 17 may be preferably 3% by mass or more, and in addition, preferably 50% by mass or less, and more preferably 40% by mass or less, based on the total nonvolatile content in the electrolyte slurry 15A. Thus, the content of the polymer 17 in the obtained electrolyte layer was the same as the above content.

The dispersion medium in the electrolyte slurry 15A may be the same dispersion medium as that used in the above-described electrode mixture slurry. The content of the dispersion medium in the electrolyte paste 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 components in the electrolyte paste 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 in the form of an ionic liquid electrolytic solution. The electrolyte paste 15A may not contain the ionic liquid and the electrolyte salt, but in this case, the electrode mixture paste contains the ionic liquid and the electrolyte salt.

When the electrolyte paste 15A contains the ionic liquid and the electrolyte salt, the ionic liquid and the electrolyte salt may be the same as those contained in the electrode mixture paste. The ionic liquid and the electrolyte salt contained in the electrolyte slurry may be the same as or different from the ionic liquid and the electrolyte salt contained in the electrode mixture slurry.

In the case where the electrolyte slurry 15A contains an ionic liquid and an electrolyte salt in the form of an ionic liquid electrolyte solution, the salt concentration of the electrolyte salt per unit volume of the ionic liquid in the ionic liquid electrolyte solution may be 0.3mol/L or more, 0.5mol/L or more, or 1.0mol/L or more, and may be 3.0mol/L or less, 2.7mol/L or less, or 2.5mol/L or less.

In the case where the electrolyte slurry 15A contains an ionic liquid electrolytic solution, 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 amount of nonvolatile components in the electrolyte slurry 15A.

From the viewpoint of improving the load characteristics of the secondary battery, the composition ratio of the oxide particles 16 and the polymer 17 in the electrolyte slurry 15A may be an oxide particle: polymer = 1. From the same viewpoint, the composition ratio of the oxide particles 16 to the ionic liquid electrolyte may be from 0 to 86 (mass ratio) with respect to the oxide particles to the polymer: ionic liquid electrolyte =6 to 67.

In the electrolyte slurry application step, the method of applying the electrolyte slurry 15A to the main surface 14A of the electrode material mixture intermediate layer 14A may be the same as the method of applying the electrode material mixture slurry to the main surface 13a of the current collector 13. The method of applying the electrolyte paste 15A may be the same as or different from the method of applying the electrode mixture paste.

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 of volatilizing the dispersion medium may be the same as the method of volatilizing the dispersion medium in the electrode mixture slurry. As a result of volatilizing the dispersion medium of the electrode mixture intermediate layer 14A and the electrolyte slurry 15A, as shown in fig. 3c, a secondary battery cell member 19A (positive electrode member or negative electrode member) including the current collector 13, the electrode mixture layer 18A (positive electrode mixture layer 10 or negative electrode mixture layer 12), and the electrolyte layer 7A in this order can be obtained.

In the manufacturing method of the present embodiment, at least one of the electrode mixture layer 14A and the electrolyte paste 15A contains an ionic liquid and an electrolyte salt (ionic liquid electrolyte solution). When the electrolyte slurry 15A is applied to the electrode mixture layer 14A, the ionic liquid electrolyte moves together with the dispersion medium from the electrode mixture layer 14A to the electrolyte slurry 15A, from the electrolyte slurry 15A to the electrode mixture layer 14A, or between the electrode mixture layer 14A and the electrolyte slurry 15A, as indicated by arrows in fig. 3 (b). It is presumed that the movement is based on the following action or phenomenon: the action of reducing the difference in concentration of the ionic liquid electrolyte between the electrode mixture intermediate layer 14A and the electrolyte paste 15A, the action of gravity, or the capillary phenomenon is intended.

According to the manufacturing method of the present embodiment, since the electrolyte layer 7A is formed by applying the electrolyte slurry 15A on the electrode mixture intermediate layer 14A, even if fine irregularities are present on the surface of the electrode mixture intermediate layer 14A, the electrolyte slurry 15A is disposed so as to fill and flatten the recesses. As a result, in the battery member 19A obtained, a good interface where the electrode mixture layer 18A and the electrolyte layer 7A closely adhere to each other is formed. In the battery member 19A, since the ionic liquid electrolyte can move between the electrolyte paste 15A and the electrode mixture layer 14A in the electrolyte paste application step, the ionic liquid electrolyte is likely to be present around the electrode active material in the electrode mixture layer 18A. Therefore, in the battery member 19A, the electrode active material/electrolyte interface is well formed.

In this way, in the battery member 19A, the interface of the electrode mixture layer 18A/the electrolyte layer 7A is formed well, and the adhesion is excellent, and the interface of the electrode active material/the electrolyte is also formed well. Therefore, the secondary battery using this battery member 19A is excellent in battery characteristics.

[ 2 nd embodiment ]

Next, a method for manufacturing a battery member for a secondary battery according to embodiment 2 will be described. Fig. 4 is a schematic cross-sectional view illustrating a method for manufacturing a battery member for a secondary battery according to embodiment 2. In this manufacturing method, as shown in fig. 4a, first, an electrode mixture intermediate layer 14B containing an electrode active material is formed on a main surface 13a of a current collector 13 (a positive electrode current collector 9 or a negative electrode current collector 11) (an electrode mixture intermediate layer forming step).

The electrode mixture intermediate layer forming step is performed by a method of applying an electrode mixture slurry to the current collector 13, as in embodiment 1. 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 those of the electrode active material and the dispersion medium in embodiment 1.

The electrode mixture paste 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 mix intermediate layer 14B further containing these materials is formed.

In one embodiment, the electrode mix 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 in the form of an ionic liquid electrolyte. The electrode mixture slurry may not contain an ionic liquid and an electrolyte salt, and in this case, a slurry (electrolyte slurry) described later will contain an ionic liquid. That is, at least one of the electrode mixture paste and the electrolyte paste contains an ionic liquid and an electrolyte salt.

When the electrode mixture paste contains the ionic liquid and the electrolyte salt, the ionic liquid and the electrolyte salt may be the same as those contained in the electrode mixture paste of embodiment 1.

In the case where the electrode mixture slurry contains an ionic liquid and an electrolyte salt in the form of an ionic liquid electrolyte, the salt concentration of the electrolyte salt per unit volume of the ionic liquid and the content of the ionic liquid electrolyte in the ionic liquid electrolyte may be in the same ranges as in embodiment 1.

The kind and content of the conductive agent and the binder may be the same as those of the conductive agent and the binder in embodiment 1 described above, respectively.

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

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

In the formula (1), X ^- Represents a counter anion. As X ^- Examples thereof include BF ₄ ^- (tetrafluoroborate anion), PF ₆ ^- (hexafluorophosphate anion), [ FSI] ^- 、[TFSI] ^- 、[f3C] ^- 、[BOB] ^- 、BF ₃ (CF ₃ ) ^- 、BF ₃ (C ₂ F ₅ ) ^- 、BF ₃ (C ₃ F ₇ ) ^- 、BF ₃ (C ₄ F ₉ ) ^- 、C(SO ₂ CF ₃ ) ₃ ^- 、CF ₃ SO ₂ O ^- 、CF ₃ COO ^- 、RCOO ^- (R is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group). Wherein X ^- Preferably selected from the group consisting of BF ₄ ^- 、PF ₆ ^- 、[FSI] ^- 、[TFSI] ^- And [ f3C] ^- At least one of the group consisting of [ TFSI ], more preferably] ^- Or [ FSI ]] ^- 。

The viscosity-average molecular weight Mv (g.mol) of the polymer having a structural unit represented by the formula (1) ^-1 ) Not particularly limited, but is preferably 1.0X 10 or more ⁵ More preferably 3.0X 10 or more ⁵ . In addition, the viscosity of the polymer is uniformThe molecular weight is preferably less than or equal to 5.0X 10 ⁶ More preferably 1.0X 10 ⁶ . In addition, if the viscosity average molecular weight is 5.0X 10 or less ⁶ The handling property when the polymer solution 20 is permeated tends to be further improved.

In the present specification, the "viscosity average molecular weight" can be evaluated by a viscosity method which is a common measurement method, and can be calculated from the limit viscosity number [ η ] measured in accordance with JIS K7367-3.

From the viewpoint of ion conductivity, the polymer having a structural unit represented by formula (1) is preferably a homopolymer which is a polymer composed only of a structural unit represented by formula (1).

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

In the formula (1A), n is 300 to 4000 ^- Represents a counter anion. Y is ^- Can use X ^- The illustrated ions are the same ions.

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. The method for producing the polymer having the structural unit represented by the formula (1) is not particularly limited, and for example, the production method described in Journal of Power Sources 2009, 188, 558-563 can be used.

A polymer (X) having a structural unit represented by the formula (1) ^- ＝[TFSI] ^- ) For example, it can be obtained by the following production method.

First, polydiallyldimethylammonium chloride ([ P (DADMA) ] [ Cl ]) was dissolved in deionized water and stirred to prepare an aqueous solution of [ P (DADMA) ] [ Cl ]. [ P (DADMA) ] [ Cl ] commercially available products can be used as they are, for example. Subsequently, li [ TFSI ] is separately dissolved in deionized water to prepare an aqueous solution containing Li [ TFSI ].

Then, the two aqueous solutions were mixed and stirred for 2 to 8 hours so that the molar ratio of Li [ TFSI ] to [ P (DADMA) ] [ Cl ] (the molar amount of Li [ TFSI ]/[ the molar amount of P (DADMA) ] [ Cl ]) was 1.2 to 2.0, and a solid was precipitated and collected by filtration. The solid was washed with deionized water and dried under vacuum for 12 to 48 hours, whereby a polymer having a structural unit represented by formula (1) [ P (DADMA) ] [ TFSI ]) could be obtained.

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, further preferably 30% by mass or more, and further preferably 80% by mass or less, more preferably 75% by mass or less, further preferably 70% by mass or less, based on the total amount of the polymer solution.

The ionic liquid and the electrolyte salt contained in the polymer solution 20 may be the same as those usable in embodiment 1 described above. The ionic liquid and the electrolyte salt contained in the polymer solution 20 may be the same as or different from those contained in the electrode mixture slurry of embodiment 2.

The ionic liquid and electrolyte salt may also be added to the polymer solution 20 in the form of an ionic liquid electrolyte. In this case, the salt concentration of the electrolyte salt per unit volume of the ionic liquid in the ionic liquid electrolyte solution may be 0.3mol/L or more, 0.5mol/L or more, or 1.0mol/L or more, or 3.0mol/L or less, 2.7mol/L or less, or 2.5mol/L or less.

The content of the ionic liquid electrolyte is preferably 3% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, and further preferably 80% by mass or less, more preferably 75% by mass or less, and further preferably 70% by mass or less, based on the total amount of the polymer solution.

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

In the polymer solution infiltration step, the method of infiltrating the polymer solution 20 into the electrode material mixture intermediate layer 14B is a method of applying the polymer solution 20 on the surface 14a of the electrode material mixture intermediate layer 14B opposite to the current collector 13, as shown in fig. 4 (B). The coating may be coating with an applicator, coating with a spray, or the like. As shown by the arrows in fig. 4B, the polymer solution 20 applied to the electrode material mixture intermediate layer 14B permeates into the electrode material mixture intermediate layer 14B, and forms an electrode material mixture intermediate layer 14C containing a polymer having a structural unit represented by formula (1) (fig. 4C).

As another method for infiltrating the polymer solution 20 into the electrode mixture layer 14B, a method of immersing the current collector 13 on which the electrode mixture layer 14B is formed in the polymer solution 20, or the like may be used.

Thereafter, as shown in fig. 4d, a slurry 15B (electrolyte slurry 15B) containing oxide particles 16, a polymer 17, and a dispersion medium is applied to a surface 14a of the electrode mixture intermediate layer 14C (the electrode mixture intermediate layer into which the polymer solution has permeated) on the side opposite to the current collector 13. (electrolyte slurry coating step).

The types and contents of the oxide particles 16, the polymer 17, and the dispersion medium contained in the electrolyte slurry 15B may be the same as those of the oxide particles 16, the polymer 17, and the dispersion medium in embodiment 1 described above, respectively.

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 in the form of an ionic liquid electrolytic solution. The ionic liquid and the electrolyte salt may be the same as those contained in the electrolyte slurry of embodiment 1 described above. The ionic liquid and the electrolyte salt contained in the electrolyte paste 15B may be the same as or different from those contained in the electrode mixture paste and the polymer solution 20 according to embodiment 2. The electrolyte slurry 15B may also be free of ionic liquid and electrolyte salt.

In the case where the electrolyte slurry 15B contains an ionic liquid and an electrolyte salt in the form of an ionic liquid electrolytic solution, the salt concentration of the electrolyte salt per unit volume of the ionic liquid in the ionic liquid electrolytic solution and the content of the ionic liquid electrolytic solution may be in the same ranges as in embodiment 1 described above.

In the electrolyte slurry 15B, the composition ratio of the oxide particles 16 to the polymer 17, the composition ratio of the oxide particles 16 to the ionic liquid electrolytic solution, and the composition ratio of the oxide particles 16, the polymer 17 to the ionic liquid electrolytic solution may be in the same ranges as those in embodiment 1.

The method of applying the electrolyte paste 15B can be performed by the same method as the electrolyte paste application step in embodiment 1 described above. The method of applying the electrolyte paste 15B may be the same as or different from the method of applying the electrode mixture paste in embodiment 2.

After the electrolyte paste application step, the dispersion medium of electrode mixture intermediate layer 14C and electrolyte paste 15B is volatilized. The method of volatilizing the dispersion medium may be the same as that in embodiment 1 described above. As a result of volatilizing the dispersion medium, as shown in fig. 4 e, a secondary battery cell member 19B (positive electrode member or negative electrode member) including the current collector 13, the electrode mixture layer 18B (positive electrode mixture layer 10 or negative electrode mixture layer 12), and the electrolyte layer 7B in this order can be obtained.

In the production method of the present embodiment, at least one of the electrode mixture layer 14C and the electrolyte paste 15B contains an ionic liquid and an electrolyte salt (ionic liquid electrolyte). When the electrolyte slurry 15B is applied to the electrode mixture intermediate layer 14C, the ionic liquid electrolyte moves together with the dispersion medium from the electrode mixture intermediate layer 14C to the electrolyte slurry 15B, from the electrolyte slurry 15B to the electrode mixture intermediate layer 14C, or between the electrode mixture intermediate layer 14C and the electrolyte slurry 15B. It is presumed that the movement is based on the following action or phenomenon: the action of reducing the difference in concentration of the ionic liquid electrolyte between the electrode mixture intermediate layer 14C and the electrolyte paste 15B, the action of gravity, or the capillary phenomenon is intended.

According to the manufacturing method of the present embodiment, since the electrolyte layer 7B is formed by applying the electrolyte paste 15B on the electrode mixture intermediate layer 14C, even if fine irregularities are present on the surface of the electrode mixture intermediate layer 14C, the electrolyte paste 15B is disposed so as to fill and flatten the recesses. As a result, in the battery member 19B obtained, a good interface where the electrode mixture layer 18B and the electrolyte layer 7B closely adhere to each other was formed. In the battery member 19B, since the ionic liquid electrolyte can move between the electrolyte paste 15B and the electrode mixture layer 14C in the electrolyte paste application step, the ionic liquid electrolyte is likely to be present around the electrode active material in the electrode mixture layer 18B. Therefore, the electrode active material/electrolyte interface is also formed well in the battery member 19B.

In this way, in the battery member 19B, the interface between the electrode mixture layer 18B and the electrolyte layer 7B is formed well, and the adhesion is excellent, and the interface between the electrode active material and the electrolyte is also formed well. Therefore, the secondary battery using this battery member 19B is excellent in battery characteristics.

In the battery member 19B, the polymer represented by the above formula (1) is contained in the electrode material mixture layer 18B. This can improve the ionic conductivity of the electrode mixture layer 18B, and can further improve the battery characteristics of a secondary battery using the battery member 19B.

The secondary battery including the battery member manufactured in each of the above embodiments may take various modifications.

As a modification 1, the method for manufacturing a battery member according to each of the above embodiments may be used as a method for manufacturing a battery member used for a so-called bipolar secondary battery. Fig. 5 is an exploded perspective view showing one embodiment of an electrode group of a secondary battery according to a modification. The secondary battery in this modification is different from the secondary battery in the above embodiment in that the electrode group 2B includes the bipolar electrode 21. That is, as shown in fig. 5, the electrode group 2B includes a positive electrode 6, a 1 st electrolyte layer 7, a bipolar electrode 21, a 2 nd electrolyte layer 7, and a negative electrode 8 in this order. The bipolar electrode 21 includes: the bipolar collector 22, the positive electrode mixture layer 10 provided on the surface (positive electrode surface) of the bipolar collector 22 on the negative electrode 8 side, and the negative electrode mixture layer 12 provided on the surface (negative electrode surface) of the bipolar collector 22 on the positive electrode 6 side.

This bipolar secondary battery can be regarded as including a secondary battery cell member (bipolar electrode member) including the 1 st electrolyte layer 7, the positive electrode mixture layer 10, the bipolar collector 22, the negative electrode mixture layer 12, and the 2 nd electrolyte layer 7 in this order. A method for manufacturing a battery member according to an embodiment of the present invention is a method for manufacturing the bipolar electrode member.

A method for manufacturing a bipolar electrode member according to one embodiment includes: a step of forming a positive electrode mixture intermediate layer on one main surface of the bipolar collector 22 (positive electrode mixture intermediate layer forming step), a step of applying a 1 st electrolyte slurry on a surface of the positive electrode mixture intermediate layer opposite to the bipolar collector 22 (1 st electrolyte slurry applying step), a step of forming a negative electrode mixture intermediate layer on the other main surface of the bipolar collector 22 (negative electrode mixture intermediate layer forming step), and a step of applying a 2 nd electrolyte slurry on a surface of the negative electrode mixture intermediate layer opposite to the bipolar collector 22 (2 nd electrolyte slurry applying step). The respective steps can be performed by the same materials and methods as those of the respective steps (electrode mixture intermediate layer forming step, electrolyte slurry coating step) in the respective embodiments described above. The composition of the 1 st electrolyte paste and the composition of the 2 nd electrolyte paste may be the same composition or different compositions, but the same composition is preferred.

In the present embodiment, the method may further include, before the electrolyte slurry coating step: and a step of infiltrating a solution containing a polymer having a structural unit represented by the above formula (1) into the positive electrode material mixture intermediate layer or the negative electrode material mixture intermediate layer (polymer solution infiltration step). The polymer solution impregnation step may be performed by the same materials and methods as those of the polymer solution impregnation step in the above embodiment.

After the electrolyte slurry coating step, the positive electrode mixture intermediate layer and the 1 st electrolyte slurry dispersion medium were volatilized. Similarly, the negative electrode mixture intermediate layer and the dispersion medium of the 2 nd electrolyte slurry are volatilized. The method of volatilizing the dispersion medium may be the same as that in the above embodiment. As a result of volatilizing the dispersion medium, a battery member for a secondary battery (bipolar electrode member) including the 1 st electrolyte layer 7, the positive electrode mixture layer 10, the bipolar collector 22, the negative electrode mixture layer 12, and the 2 nd electrolyte layer 7 in this order can be obtained.

In the bipolar electrode member thus obtained, the interface of the positive electrode mixture layer/the 1 st electrolyte layer and the interface of the negative electrode mixture layer/the 2 nd electrolyte layer were formed well, and the adhesion was excellent, and the interface of the electrode active material/the electrolyte was also formed well. Therefore, a secondary battery (bipolar secondary battery) using the battery member is excellent in battery characteristics.

As a modification example 2, the method for manufacturing a battery member according to each of the above embodiments may further include a step of stacking different electrolyte layers (second electrolyte layers) on the electrolyte layers (first electrolyte layers) 7A and 7B after the electrolyte layers 7A and 7B are formed. In this case, the 1 st electrolyte layer can be referred to as an interface-forming layer because the 1 st electrolyte layer functions to form a good interface between the electrode mixture layer and the 2 nd electrolyte layer. A secondary battery using the battery member obtained by the manufacturing method includes, as an electrode group, a positive electrode current collector, a positive electrode mixture layer, a 1 st interface formation layer, an electrolyte layer (2 nd electrolyte layer), a 2 nd interface formation layer, a negative electrode mixture layer, and a negative electrode current collector in this order.

In one embodiment, the electrode group may be regarded as including the 1 st cell member (positive electrode member) including a positive electrode current collector, a positive electrode mixture layer, a 1 st interface forming layer, and an electrolyte layer in this order. Similarly, the electrode group may be regarded as including a 2 nd battery member (negative electrode member) including a negative electrode current collector, a negative electrode mixture layer, a 2 nd interface formation layer, and an electrolyte layer in this order. The manufacturing method according to modification 2 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 of the above embodiments. That is, the manufacturing method according to the present modification is a method in which the electrolyte layer is changed to the interface forming layer in each of the above embodiments.

In this manufacturing method, the electrolyte layer is disposed on the surface of the positive electrode member on the 1 st interface formation layer side or on the surface of the negative electrode member on the 2 nd interface formation layer side, whereby the battery member can be manufactured. In one embodiment, the electrolyte layer in this case may be formed by forming the electrolyte slurries 15A and 15B into a sheet shape. That is, a base material such as a film made of a resin is prepared, and the electrolyte sheet is produced by applying the electrolyte slurries 15A and 15B to the base material and then volatilizing the dispersion medium. Then, the electrolyte layer can be obtained by peeling the base material from the electrolyte sheet.

In another embodiment, the electrolyte layer may have a composition different from that of the electrolyte layer made of the electrolyte slurries 15A and 15B, and may be, for example, an electrolyte layer obtained by molding a known electrolyte composition such as an organic polymer solid electrolyte or an inorganic solid electrolyte into a sheet 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 (wherein 0 ≦ c < 2 and 0 ≦ d < 3. In the formula, and (Ti, ge) means either one of Ti and Ge or both of Ti and Ge), and Li ₁₀ GeP ₂ S ₁₂ 、Li _9.54 Si _1.74 P _1.44 S _11.7 Cl _0.3 And the like.

In the battery member obtained in this way, the interface of the positive electrode mixture layer/the 1 st interface formation layer and the interface of the negative electrode mixture layer/the 2 nd interface formation layer are formed well, and the adhesion is excellent, and the interface of the electrode active material/the electrolyte is also formed well. Further, by including the ionic liquid electrolytic solution in the interface forming layer, ion conduction between the interface forming layer and the electrolyte layer becomes easier. As a result, the secondary battery using the battery member according to the present modification can be said to have excellent battery characteristics because the interfaces between the layers are formed well.

Examples

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the following description, when a composition of an ionic liquid (ionic liquid electrolytic solution) in which an electrolyte salt is dissolved is expressed, the expression "concentration of the electrolyte salt/kind of the ionic liquid" may be used.

< example 1 >

[ production of Positive electrode Member ]

70 parts by mass of a 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 diameter 48nm, manufactured by DENKA K.K.), 9 parts by mass of a copolymer solution (solid content 12% by mass) of vinylidene fluoride and hexafluoropropylene, and N-methyl-N-propylpyrrolidine as an ionic liquid

Bis (fluorosulfonyl) imide lithium salt (Li [ FSI ]) as an electrolyte salt was dissolved in bis (fluorosulfonyl) imide (Py 13-FSI)]) The obtained ionic liquid electrolyte (1.5M/Li [ FSI ]]Py 13-FSI) 14 parts by mass was dispersed in 250 parts by mass of N-methyl-2-pyrrolidone (NMP) as a dispersion medium to prepare a positive electrode mixture slurry. The positive electrode mixture slurry was mixed at 125g/m ² The coating amount of (2) was applied to a positive electrode current collector (aluminum foil 20 μm thick), dried by heating at 80 ℃ for 12 hours, and pressed to give a mixture density of 2.7g/cm ³ The positive electrode mixture intermediate layer (2). After cutting the sheet into a width of 30mm and a length of 45mm, a positive electrode collector tab was attached.

A copolymer of vinylidene fluoride as a 1 st structural unit and hexafluoropropylene as a 2 nd structural unit (mass ratio of the content of the 1 st structural unit to the content of the 2 nd structural unit = 95/5).Hereinafter, also referred to as PVDF-HFP. ) 40 parts by mass and SiO as oxide particles ₂ 60 parts by mass of particles (average particle diameter: 0.1 μm) were dispersed in 300 parts by mass of NMP as a dispersion medium to prepare an electrolyte slurry. The obtained electrolyte slurry was applied to the surface of the positive electrode mixture intermediate layer opposite to the positive electrode current collector, and heated at 80 ℃ for 12 hours to volatilize the dispersion medium, thereby forming an electrolyte layer. This provides a positive electrode member comprising a positive electrode current collector, a positive electrode mixture layer, and an electrolyte layer in this order. The thickness of the electrolyte layer in the obtained positive electrode member was 15 ± 2 μm.

[ production 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 diameter 48nm, manufactured by DENKA Co., ltd.), 7.8 parts by mass of a copolymer solution (solid content: 12% by mass) of vinylidene fluoride and hexafluoropropylene, and 1.5M/Li [ FSI ] of an ionic liquid electrolyte solution (1.5M/Li [ FSI ]) in which an electrolyte salt is dissolved]33.2 parts by mass of/Py 13-FSI) was dispersed in 250 parts by mass of NMP as a dispersion medium to prepare a negative electrode mixture slurry. The negative electrode mixture slurry was mixed at a ratio of 60g/m ² The amount of (2) was applied to a current collector (copper foil 10 μm in thickness), and the resultant was dried by heating at 80 ℃ for 12 hours to give a mixture density of 1.8g/cm ³ The negative electrode mixture intermediate layer of (3). The resultant was cut into a width of 31mm and a length of 46mm, and then a negative electrode collector tab was attached.

In the same manner as in the method for producing the positive electrode member, the electrolyte slurry is applied to the surface of the negative electrode mixture intermediate layer opposite to the negative electrode current collector, and the dispersion medium is evaporated to form the electrolyte layer. This provides a negative electrode member comprising a negative electrode current collector, a negative electrode mixture layer, and an electrolyte layer in this order. The thickness of the electrolyte layer in the obtained negative electrode member was 15. + -.2. Mu.m.

[ production of lithium ion Secondary Battery ]

The prepared positive electrode member and negative electrode member were laminated so that the electrolyte layers thereof were in contact with each other, thereby preparing an electrode group. The electrode group was housed in a battery case made of a laminated film made of aluminum as shown in fig. 1. In this battery exterior package, the opening of the battery container was sealed so that the positive electrode current collector tab and the negative electrode current collector tab were led out to the outside, and the lithium ion secondary battery of example 1 was produced. The aluminum laminate film is a laminate of a polyethylene terephthalate (PET) film, an aluminum foil, and a sealing layer (polypropylene or the like). The designed capacity of the lithium ion secondary battery was 20mAh.

< example 2 >

A lithium ion secondary battery was produced in the same manner as in example 1, except that the content of the polymer in the electrolyte slurry was changed to 50 parts by mass and the content of the oxide particles was changed to 50 parts by mass in example 1.

< example 3 >

A lithium ion secondary battery was produced in the same manner as in example 1 except that 14 parts by mass of an ionic liquid electrolyte solution (1.5M/Li [ FSI ]/Py 13-FSI) prepared by dissolving Li [ FSI ] as an electrolyte salt in Py13-FSI as an ionic liquid was further added to the electrolyte slurry in example 1.

< example 4 >

A lithium ion secondary battery was produced in the same manner as in example 3, except that the content of the ionic liquid electrolyte solution (1.5M/Li [ FSI ]/Py 13-FSI) in the electrolyte slurry in example 3 was changed to 9 parts by mass.

< example 5 >

A lithium ion secondary battery was produced in the same manner as in example 3, except that the content of the polymer in the electrolyte slurry was changed to 30 parts by mass, the content of the oxide particles was changed to 20 parts by mass, and the content of the ionic liquid (1.5M/Li [ FSI ]/Py 13-FSI) was changed to 50 parts by mass in example 3.

< example 6 >

[ production of Positive electrode Member ]

(formation of Positive electrode mixture intermediate layer)

92.5 parts by mass of a layered lithium-nickel-manganese-cobalt composite oxide (positive electrode active material), 2.5 parts by mass of acetylene black (conductive agent, product name: HS-100, average particle diameter 48nm, manufactured by DENKA K.K.) was addedThe positive electrode mixture slurry was prepared by dispersing 5 parts by mass of a copolymer solution (solid content 12% by mass) of vinylidene fluoride and hexafluoropropylene in 250 parts by mass of NMP as a dispersion medium. The positive electrode mixture slurry was mixed at 125g/m ² The coating amount of (2) was applied to a positive electrode current collector (aluminum foil 20 μm thick), dried by heating at 80 ℃ for 12 hours, and pressed to give a mixture density of 2.7g/cm ³ The positive electrode mixture intermediate layer (2). After cutting the sheet into a width of 30mm and a length of 45mm, a positive electrode current collecting tab was attached.

(Synthesis of Polymer used in Polymer solution)

By adding a counter anion [ Cl ] of polydiallyldimethylammonium chloride] ^- Change to [ TFSI ]] ^- To synthesize a polymer having a structural unit represented by the formula (1). First, the mixture was diluted with 500 parts by mass of distilled water [ P (DADMA)][Cl]100 parts by mass of an aqueous solution (20% by mass aqueous solution, manufactured by Aldrich) were added to obtain a diluted solution of the polymer. Then, li [ TFSI ] is added](Tayota chemical Co., ltd.) 43 parts by mass was dissolved in 100 parts by mass of water to prepare Li [ TFSI ]]An aqueous solution. Mixing the Li [ TFSI ]]After the aqueous solution was dropwise added to the diluted solution, 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 precipitate was dried under vacuum at 105 ℃ to evaporate water, thereby obtaining [ P (DADMA) which is a polymer having a structural unit represented by the formula (1)][TFSI]。[P(DADMA)][TFSI]Has a viscosity average molecular weight of 2.11X 10 ⁶ g·mol ^-1 。

The viscosity average molecular weight Mv is calculated based on the formula of = KMv (where K represents a spreading factor, and its value depends on temperature, polymer, and solvent properties) after measuring the viscosity [. Eta. ] of a polymer at 25 ℃ using polymethyl methacrylate (PMMA) as a standard substance using an ubbelohde viscometer.

(preparation and application of Polymer solution)

To 24 parts by mass of the obtained polymer ([ P (DADMA) ] [ TFSI ]), 18 parts by mass of Li [ FSI ] as an electrolyte salt, 58 parts by mass of Py13-FSI (manufactured by kanto chemical corporation) as an ionic liquid, 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 coated on the positive electrode material mixture intermediate layer at a gap of 150 μm by a doctor blade method. Thereafter, the polymer solution was dried under vacuum at 60 ℃ for 12 hours. Thus, the positive electrode mixture intermediate layer contains the polymer represented by formula (1).

Next, an electrolyte slurry having the same composition as in example 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 obtained in the same manner as in example 1.

[ production of negative electrode Member ]

A negative electrode mixture slurry was prepared by dispersing 92 parts by mass of graphite (negative electrode active material, available from Hitachi chemical Co., ltd.), 3 parts by mass of acetylene black (conductive agent, product name: HS-100, average particle diameter 48nm, available from DENKA Co., ltd.), and 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. The negative electrode mixture slurry was mixed at a ratio of 60g/m ² The amount of (2) was applied to a current collector (copper foil having a thickness of 10 μm), dried by heating at 80 ℃ for 12 hours, and pressed to give a mixture having a density of 1.8g/cm ³ The negative electrode mixture intermediate layer of (3). The resultant was cut into a width of 31mm and a length of 46mm, and then a negative electrode collector tab was attached.

Similarly to the positive electrode member, the negative electrode mixture intermediate layer contains a polymer containing [ P (DADMA) ] [ TFSI ], which is a polymer having a structural unit represented by formula (1). 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 in the same manner as in example 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.

< example 7 >

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

< example 8 >

[ production of Positive electrode Member ]

92.5 parts by mass of a layered lithium-nickel-manganese-cobalt composite oxide (positive electrode active material), 2.5 parts by mass of acetylene black (conductive agent, product name: HS-100, average particle diameter 48nm, manufactured by DENKA K.K.), and 5 parts by mass of a copolymer solution of vinylidene fluoride and hexafluoropropylene (solid content: 12% by mass) were dispersed in 250 parts by mass of NMP as a dispersion medium to prepare a positive electrode mixture slurry. The positive electrode mixture slurry was applied at a coating weight of 125g/m ² Applied to a positive electrode current collector (aluminum foil having a thickness of 20 μm), dried by heating at 80 ℃ for 12 hours, and pressed to give a mixture having a density of 2.7g/cm ³ The positive electrode mixture intermediate layer (2). After cutting the sheet into 30mm and 45mm in length, a positive electrode collector tab was attached.

PVDF-HFP 30 parts by mass and SiO ₂ 20 parts by mass of particles (average particle diameter 0.1 μ M) and an ionic liquid electrolyte (1.5M/Li [ FSI ]]Py 13-FSI) 50 parts by mass was dispersed in 300 parts by mass of NMP as a dispersion medium to prepare an electrolyte slurry. The obtained electrolyte slurry was applied to the surface of the positive electrode mixture intermediate layer opposite to the positive electrode current collector, and heated at 80 ℃ for 12 hours to volatilize the dispersion medium, thereby forming an electrolyte layer. This provides a positive electrode member comprising a positive electrode current collector, a positive electrode mixture layer, and an electrolyte layer in this order. The thickness of the electrolyte layer in the obtained positive electrode member was 15 ± 2 μm.

[ production of negative electrode Member ]

A negative electrode mixture slurry was prepared by dispersing 92 parts by mass of graphite (negative electrode active material, manufactured by Hitachi chemical Co., ltd.), 3 parts by mass of acetylene black (conductive agent, product name: HS-100, average particle diameter 48nm, manufactured by DENKA Co., ltd.), and 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. The negative electrode mixture slurry was mixed at a ratio of 60g/m ² The amount of (2) was applied to a current collector (copper foil 10 μm thick), dried by heating at 80 ℃ for 12 hours, and pressed to give a mixture density of 1.8g/cm ³ Of the negative electrodeAn adhesive intermediate layer. After cutting the sheet into pieces having a width of 31mm and a length of 46mm, a negative electrode collector tab was attached.

In the same manner as in the method for producing the positive electrode member, the electrolyte slurry is applied to the surface of the negative electrode mixture intermediate layer opposite to the negative electrode current collector, and the dispersion medium is evaporated to form the electrolyte layer. This provides a negative electrode member comprising a negative electrode current collector, a negative electrode mixture layer, and an electrolyte layer in this order. The thickness of the electrolyte layer in the obtained negative electrode member was 15. + -.2. Mu.m.

[ 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.

< example 9 >

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

< confirmation of adhesion of electrode mixture layer to electrolyte layer >

The positive electrode member and the negative electrode member (battery member) according to example 8 were each cut using an ion milling apparatus (E-3500, manufactured by hitachi high and new technologies, ltd.) so that the cross section of the battery member was exposed. The cross section was observed with a scanning electron microscope (SEM, JSM-6010LA, manufactured by japan electronics corporation), and whether or not a portion where peeling occurred was present between the electrode mixture layer and the electrolyte layer was visually confirmed. In addition, it was confirmed whether or not voids were present around the electrode active materials (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 8. Fig. 6 (a) shows a cross section of the positive electrode member, and fig. 6 (b) 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 8, there was no portion where peeling occurred between the electrode mixture layer and the electrolyte layer, and it was judged that the adhesion between the electrode mixture layer and the electrolyte layer was good. Further, since no voids were observed around the electrode active material, it was judged that the interface between the electrode active material and the electrolyte was formed satisfactorily. In examples 1 to 7 and 9 as well, it was confirmed by observing the cross section that the adhesion between the electrode mixture layer and the electrolyte layer was good and the interface between the electrode active material and the electrolyte was well formed.

Claims (4)

1. A method for manufacturing a battery member for a secondary battery, comprising:

a step of forming an electrode mixture intermediate layer containing an electrode active material on a main surface of a current collector, and

coating a surface of the electrode mixture intermediate layer opposite to the current collector with a coating material containing a material 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 A step of forming a slurry of at least one particle of the group and a polymer,

at least one of the electrode mixture intermediate layer and the slurry contains an ionic liquid and an electrolyte salt.

2. The production method according to claim 1, wherein one of the electrode material mixture intermediate layer and the slurry contains the ionic liquid and the electrolyte salt.

3. The production method according to claim 1, wherein both the electrode mixture intermediate layer and the slurry contain the ionic liquid and the electrolyte salt.

4. The production method according to any one of claims 1 to 3, further comprising a step of infiltrating the electrode material mixture intermediate layer with a solution containing a polymer having a structural unit represented by the following formula (1),

in the formula (1), X ^- Represents a counter anion.

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