JP6595348B2 - Solid electrolyte composition, solid electrolyte sheet for all-solid-state secondary battery, electrode sheet for all-solid-state secondary battery, all-solid-state secondary battery, and branched polymer production method - Google Patents

Description

  The present invention relates to a solid electrolyte composition, a solid electrolyte sheet for an all-solid secondary battery, an electrode sheet for an all-solid secondary battery, an all-solid secondary battery, and a branched polymer production method.

A lithium ion secondary battery is a storage battery that has a negative electrode, a positive electrode, and an electrolyte sandwiched between the negative electrode and the positive electrode, and enables recharging and discharging by reciprocating lithium ions between the two electrodes. Conventionally, an organic electrolytic solution has been used as an electrolyte in a lithium ion secondary battery. However, the organic electrolyte is liable to leak, and there is a possibility that a short circuit may occur inside the battery due to overcharge or overdischarge, resulting in ignition, and further improvements in reliability and safety are required.
Under such circumstances, all-solid secondary batteries using an inorganic solid electrolyte instead of an organic electrolyte have attracted attention. All-solid-state secondary batteries are made of a solid anode, electrolyte, and cathode, which can greatly improve safety and reliability, which is a problem with batteries that use organic electrolytes, and can extend their life. It will be. Furthermore, the all-solid-state secondary battery can have a structure in which electrodes and an electrolyte are directly arranged in series. Therefore, it is possible to increase the energy density as compared with a secondary battery using an organic electrolyte, and application to an electric vehicle, a large storage battery, and the like is expected.

  In such an all-solid secondary battery, a solid electrolyte layer or an active material layer, or a layer or material containing an inorganic solid electrolyte, further an active material, and a polymer binder as a material for forming these layers. Proposed. For example, Patent Document 1 describes a solid electrolyte layer containing a specific sulfide solid electrolyte material and a branched polymer. Patent Document 2 discloses a composition comprising a specific crosslinking agent having three unsaturated functional groups at its terminal, a specific polyalkylene glycol alkyl ether (meth) acrylic acid, a lithium salt, and a curing initiator. A solid polymer electrolyte obtained by curing an object is described.

International Publication No. 2011/64936 JP 2001-40168 A

  In recent years, development of all-solid-state secondary batteries is progressing rapidly, and performance required for all-solid-state secondary batteries is also increasing. In particular, in an all-solid-state secondary battery in which the electrode active material layer and the solid electrolyte layer are formed of solid particles, in order to improve battery performance such as cycle characteristics, a solid particle-electrode collection is achieved between solid particles. It is hoped that the binding between solid particles or between solid particles and current collectors can be improved while suppressing the decrease in ionic conductivity between them (between solid particles and current collectors). It is rare.

  It is an object of the present invention to provide a solid electrolyte composition that maintains high ionic conductivity and realizes high binding properties between solid particles or between solid particles and a current collector in an all-solid secondary battery. To do. Moreover, this invention makes it a subject to provide the solid electrolyte sheet for all-solid-state secondary batteries, the electrode sheet for all-solid-state secondary batteries, and the all-solid-state secondary battery using the said solid electrolyte composition. Furthermore, this invention makes it a subject to provide the manufacturing method of the branched polymer used for the said solid electrolyte composition.

The inventors polymerize a specific monomer in the presence of a specific amount of a polymerization initiator, and incorporate a polar substituent (also referred to as a polymerization initiator residue) generated by cleavage of the polymerization initiator into the molecule . The branched polymer (also referred to as a branched crosslinked polymer ) can be used as a polymer binder (binder) for binding solid particles such as an inorganic solid electrolyte or an active material used in an all-solid secondary battery, Furthermore, it has been found that this branched cross - linked polymer can enhance the binding properties between solid particles or between solid particles and a current collector, while maintaining high ionic conductivity in an all-solid secondary battery. It was. The present invention has been further studied based on these findings and has been completed.

That is, the above problem has been solved by the following means.
<1> A solid electrolyte composition having an inorganic solid electrolyte having conductivity of ions of metal elements belonging to Group 1 or Group 2 of the periodic table, and a polymer binder,
The polymeric binder, more than two at the end of the polymer molecules having a crosslinked structure, have a polar substituent group derived from a polymerization initiator of the polymer molecules, and the crosslinked structure having a linking group containing an alkylene oxide group containing branched crosslinked polymer solid electrolyte composition.
<2> The branched crosslinked polymer is a polymer in which the number of moles of linking groups [Bn] and the number of moles of polar substituents [Bs] satisfy the relationship [Bs] / [Bn] ≧ 0.1 <1>. The solid electrolyte composition according to 1>.
<3> the polar substituents are polar substituent derived from at least one polymerization initiator of the heat radical polymerization initiator and a chain transfer agent <1> or solid electrolyte composition according to <2>.
<4> The polar substituent has at least one group selected from the group consisting of a cyano group, an ester group, a heterocyclic group, an amidine group, an acyl group, an amide group, an alkoxy group, and a sulfide group. <3> Solid electrolyte composition as described in any one of.
<5> The solid electrolyte composition according to any one of <1> to <4>, wherein the polar substituent is represented by any of the following formulas (S1) to (S7).

In formulas (S1) to (S7), L represents a divalent linking group. X represents an oxygen atom or a sulfur atom. R ^s11 , R ^s21 , R ^s41 , R ^s42 , R ^s61 and R ^s71 each independently represent a substituent. n ^{s11 to} n ^s51 are each independently an integer of 0 to 10. Q ^s5 represents a heterocyclic ring containing -C = N-. * Represents a linking site to the end of the polymer molecule.
<6> The solid electrolyte composition according to <5>, wherein the formulas (S1) to (S5) are the following formulas (S1B) to (S5B), respectively.

In formulas (S1B) to (S5B), X represents an oxygen atom or a sulfur atom. R ^s11, represents a ^{R s13, R s14, R s21} , R s23, R s24, R s33, R s34, R s41, R s42, R s43, R s44, R s53 and ^{R s54} each independently represent a substituted group. Q ^s5 represents a heterocyclic ring containing -C = N-. * Represents a linking site to the end of the polymer molecule.
<7> linking group, an oxygen atom, a nitrogen atom, a sulfur atom, at least one heteroatom selected from the group consisting of a phosphorus atom or a silicon atom in any one of including <1> to <6> The solid electrolyte composition described.
<8 > The solid electrolyte composition according to any one of <1> to <7>, wherein the linking group includes an alkylene oxide group as a repeating unit .
< 9 > The polymer binder contains at least one of a metal salt containing a metal element ion belonging to Group 1 or Group 2 of the periodic table and a molten salt, and any one of <1> to < 8 > The solid electrolyte composition described in 1.
< 10 > The solid electrolyte composition according to any one of <1> to < 9 >, wherein the weight average molecular weight of the branched crosslinked polymer is 1000 to 300,000 in terms of polystyrene by gel permeation chromatography.
< 11 > The solid electrolyte composition according to any one of <1> to < 10 >, which contains an active material capable of inserting and releasing ions of metal elements belonging to Group 1 or Group 2 of the Periodic Table.
< 12 > The mass ratio [A + E] / [B] of the total content [A + E] of the inorganic solid electrolyte and the electrode active material with respect to the content [B] of the polymer binder is in the range of 1,000 to 1. Solid electrolyte composition as described in any one of 1>-< 11 >.
< 13 > A solid electrolyte sheet for an all-solid-state secondary battery, wherein the solid electrolyte composition according to any one of <1> to < 10 > and < 12 > is formed on a substrate.
< 14 > An electrode sheet for an all-solid-state secondary battery, in which the solid electrolyte composition according to < 11 > is formed on a metal foil.
< 15 > An all-solid secondary battery comprising a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer,
An all-solid-state secondary battery in which at least one of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer is a layer formed of the solid electrolyte composition according to any one of <1> to < 12 >. .

In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the present specification, when “acryl” or “(meth) acryl” is simply described, it means methacryl and / or acryl.

When the solid electrolyte composition of the present invention is used as a material for a solid electrolyte layer and / or an active material layer of an all-solid-state secondary battery, it can maintain high ionic conductivity and achieve high binding properties. Excellent effect. Further, the all-solid-state secondary battery sheet, all-solid-state secondary battery electrode sheet, and all-solid-state secondary battery of the present invention utilize the solid electrolyte composition that exhibits the above-described excellent effects, and have excellent cycle characteristics, Exhibits battery performance such as high temperature stability.
Moreover, according to the manufacturing method of this invention, the branched polymer used for the solid electrolyte composition of this invention can be manufactured suitably.

It is a longitudinal cross-sectional view which shows typically the all-solid-state secondary battery which concerns on preferable embodiment of this invention. It is a longitudinal cross-sectional view which shows typically the all-solid-state secondary battery (coin battery) produced in the Example.

  The solid electrolyte composition of the present invention includes a specific inorganic solid electrolyte and a polymer binder containing a branched polymer having three or more polymerization initiator residues of the polymer molecule at the terminal of the polymer molecule. Hereinafter, preferred embodiments thereof will be described. First, an all-solid secondary battery using the solid electrolyte composition of the present invention will be described.

[All-solid secondary battery]
The all solid state secondary battery of the present invention includes a positive electrode, a negative electrode facing the positive electrode, and a solid electrolyte layer between the positive electrode and the negative electrode. The positive electrode has a positive electrode active material layer on a positive electrode current collector. The negative electrode has a negative electrode active material layer on a negative electrode current collector.
At least one of the negative electrode active material layer, the positive electrode active material layer, and the solid electrolyte layer is preferably formed of the solid electrolyte composition of the present invention, which will be described later, and among them, all the layers are the solid electrolyte composition of the present invention. More preferably, it is formed by.
The active material layer or the solid electrolyte layer formed of the solid electrolyte composition is preferably the same as that in the solid content of the solid electrolyte composition with respect to the component species to be contained and the content ratio thereof.
Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited thereto.

FIG. 1 is a cross-sectional view schematically showing an all solid state secondary battery (lithium ion secondary battery) according to a preferred embodiment of the present invention. The all-solid-state secondary battery 10 according to this embodiment includes a negative electrode current collector 1, a negative electrode active material layer 2, a solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector 5 stacked in this order as viewed from the negative electrode side. The adjacent layers are in direct contact with each other. By adopting such a structure, at the time of charging, electrons (e ⁻ ) are supplied to the negative electrode side, and lithium ions (Li ⁺ ) are accumulated therein. On the other hand, at the time of discharging, lithium ions (Li ⁺ ) accumulated in the negative electrode are returned to the positive electrode side, and electrons can be supplied to the working part 6. In the example of the illustrated all-solid-state secondary battery, a light bulb is adopted as a model for the operation site 6 and is lit by discharge.

[Positive electrode active material layer, solid electrolyte layer, negative electrode active material layer]
In the all-solid-state secondary battery 10, all of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are formed of the solid electrolyte composition of the present invention.
That is, the solid electrolyte layer 3 includes an inorganic solid electrolyte and a polymer binder described later. The solid electrolyte layer usually does not contain a positive electrode active material and / or a negative electrode active material. In the solid electrolyte layer 3, a polymer binder, particularly a branched polymer described later, is present between solid particles such as an inorganic solid electrolyte and an active material contained in an adjacent active material layer. The binding property is high.
Each of the positive electrode active material layer 4 and the negative electrode active material layer 2 (sometimes referred to as an active material layer) includes a positive electrode active material or a negative electrode active material, and further includes an inorganic solid electrolyte and a polymer binder. . The active material layer includes a polymer binder, particularly a branched polymer described later, between the solid particles, between the active material layer-solid electrolyte layer and between the active material layer and the current collector. The nature is getting higher. When the active material layer contains an inorganic solid electrolyte, the ionic conductivity can be further increased.

In the present invention, when a polymer binder described below, particularly a branched polymer, is used (contained) in combination with solid particles such as an inorganic solid electrolyte or an active material, ion conduction between the solid particles or between the solid particles and the current collector is performed. The degree of improvement and the binding strength can be improved.
Although its action and mechanism are not clear, it can be considered as follows. That is, the branched polymer contained in the polymer binder has a high-density three-dimensional cross-linked structure, and three or more polymerization initiator residues (also referred to as fragments) per molecule of the polymer at the terminal. Have. Therefore, for example, when the solid particles and the branched polymer are allowed to coexist, interaction between three or more residues of the branched polymer and the solid particles occurs. In particular, the residue derived from the polymerization initiator shows a strong interaction with the solid particles. Further, the main chain of the branched polymer or the linking group described later covers the surface of the solid particles. Accordingly, the solid particles can be bound with a strong binding force without reducing the ionic conductivity between the solid particles. This interaction is not particularly limited as long as it is bound to a branched polymer and solid particles, an active material or a current collector. Although the interaction is not uniquely defined, for example, adsorption (including chemical adsorption and physical adsorption) or chemical reaction can be considered.

Moreover, the solid electrolyte composition containing the polymer binder can form a flexible layer while binding the solid particles. Moreover, it is excellent in manufacturing suitability.
The all-solid-state secondary battery of the present invention that uses a polymer binder that exhibits high binding properties with solid particles or the like is used to release and absorb ions of metal elements belonging to Group 1 or Group 2 of the periodic table. Due to the shrinkage and expansion of the active material that accompanies the charging / discharging of the solid secondary battery), the solid binding state between the active material and the solid electrolyte is maintained, and excellent battery characteristics such as cycle characteristics and high-temperature stability are maintained. Show. In particular, in the present invention, when a polymer binder is used as solid particles in combination with a sulfide-based inorganic solid electrolyte described later, these interactions become stronger and further excellent battery characteristics are exhibited. In the present invention, the metal element is preferably an element belonging to the first group, and lithium element is particularly preferable.

  In this specification, either or both of the positive electrode active material layer and the negative electrode active material layer may be simply referred to as an active material layer or an electrode active material layer. One or both of the positive electrode active material and the negative electrode active material may be simply referred to as an active material or an electrode active material.

  The thicknesses of the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2 are not particularly limited. In consideration of general battery dimensions, the thickness of each layer is preferably 10 to 1,000 μm, and more preferably 20 μm or more and less than 500 μm. In the all solid state secondary battery of the present invention, it is more preferable that the thickness of at least one of the positive electrode active material layer 4, the solid electrolyte layer 3 and the negative electrode active material layer 2 is 50 μm or more and less than 500 μm.

[Current collector (metal foil)]
The positive electrode current collector 5 and the negative electrode current collector 1 (sometimes collectively referred to as a current collector) are preferably electronic conductors.
Materials for forming the positive electrode current collector include aluminum, aluminum alloy, stainless steel, nickel, and titanium, as well as the surface of aluminum or stainless steel treated with carbon, nickel, titanium, or silver (forming a thin film) Among them, aluminum, an aluminum alloy, or stainless steel is more preferable.
As a material for forming the negative electrode current collector, aluminum, copper, copper alloy, stainless steel, nickel or titanium is preferable, and aluminum, copper, copper alloy or stainless steel is more preferable.

As the shape of the current collector, a film sheet is usually used, but a net, punched, lath, porous, foam, or fiber group molded body can also be used.
Although the thickness of a collector is not specifically limited, 1-500 micrometers is preferable. Moreover, it is also preferable that the current collector surface is roughened by surface treatment.

  In the present invention, a functional layer or member is appropriately interposed or disposed between or outside each of the negative electrode current collector, the negative electrode active material layer, the solid electrolyte layer, the positive electrode active material layer, and the positive electrode current collector. May be. Each layer may be composed of a single layer or a plurality of layers.

[Case]
The basic structure of the all-solid-state secondary battery can be manufactured by arranging each of the above layers. Depending on the application, it may be used as an all-solid secondary battery as it is, but in order to obtain a dry battery, it is further sealed in a suitable housing. The housing may be metallic or made of resin (plastic). When using a metallic thing, the thing made from an aluminum alloy or stainless steel can be mentioned, for example. The metallic housing is preferably divided into a positive-side housing and a negative-side housing and electrically connected to the positive current collector and the negative current collector, respectively. The casing on the positive electrode side and the casing on the negative electrode side are preferably joined and integrated via a gasket for preventing a short circuit.

[Solid electrolyte composition]
[Inorganic solid electrolyte]
The solid electrolyte composition of the present invention contains an inorganic solid electrolyte.
The solid electrolyte of an inorganic solid electrolyte is a solid electrolyte that can move ions inside. Since it does not contain organic substances as the main ion conductivity material, organic solid electrolytes (polymer electrolytes typified by polyethylene oxide (PEO), etc., or organics typified by lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), etc. It is clearly distinguished from the electrolyte salt). In addition, since the inorganic solid electrolyte is solid in a steady state, it is not dissociated or released into cations and anions. In this respect, the electrolyte is also clearly distinguished from inorganic electrolyte salts (LiPF ₆ , LiBF ₄ , lithium bis (fluorosulfonyl) imide (LiFSI), LiCl, etc.) in which cations and anions are dissociated or liberated in the polymer. Is done. The inorganic solid electrolyte is not particularly limited as long as it has conductivity of ions of metal elements belonging to Group 1 or Group 2 of the Periodic Table, and generally does not have electron conductivity. When the all solid state secondary battery of the present invention is a lithium ion battery, the inorganic solid electrolyte preferably has an ionic conductivity of lithium ions.
As the inorganic solid electrolyte, a solid electrolyte material applied to this type of product can be appropriately selected and used. Typical examples of inorganic solid electrolytes include (i) sulfide-based inorganic solid electrolytes and (ii) oxide-based inorganic solid electrolytes. In the present invention, a sulfide-based inorganic solid electrolyte is preferably used from the viewpoint that a better interface can be formed between the active material and the inorganic solid electrolyte.
(I) Sulfide-based inorganic solid electrolyte The sulfide-based inorganic solid electrolyte contains a sulfur atom (S) and has ionic conductivity of a metal element belonging to Group 1 or Group 2 of the periodic table, And what has electronic insulation is preferable. The sulfide-based inorganic solid electrolyte preferably contains at least Li, S and P as elements and has lithium ion conductivity. However, depending on the purpose or the case, other than Li, S and P may be used. An element may be included.
For example, a lithium ion conductivity inorganic solid electrolyte satisfying the composition represented by the following formula (1) can be mentioned and preferred.

L _a1 M _b1 P _c1 S _d1 A _e1 (1)

In the formula, L represents an element selected from Li, Na and K, and Li is preferred.
M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge. Among these, B, Sn, Si, Al, or Ge is preferable, and Sn, Al, or Ge is more preferable.
A represents I, Br, Cl or F, I or Br is preferred, and I is particularly preferred.
a1 to e1 indicate the composition ratio of each element, and a1: b1: c1: d1: e1 satisfies 1 to 12: 0 to 1: 1: 2 to 12: 0 to 5. a1 is further preferably 1 to 9, and more preferably 1.5 to 4. b1 is preferably 0 to 0.5. Further, d1 is preferably 3 to 7, and more preferably 3.25 to 4.5. Further, e1 is preferably 0 to 3, and more preferably 0 to 1.

  In the formula (1), the composition ratio of L, M, P, S and A is preferably such that b1 and e1 are 0, more preferably b1 = 0 and e1 = 0 and the ratio of a1, c1 and d1 is a1: c1: d1 = 1-9: 1: 3-7, more preferably b1 = 0, e1 = 0 and a1: c1: d1 = 1.5-4: 1: 3.25-4. 5. As will be described later, the composition ratio of each element can be controlled by adjusting the blending amount of the raw material compound when producing the sulfide-based inorganic solid electrolyte.

The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystallized (glass ceramic), or only a part may be crystallized. For example, Li—PS—S glass containing Li, P and S, or Li—PS glass glass ceramic containing Li, P and S can be used.
The sulfide-based inorganic solid electrolyte includes [1] lithium sulfide (Li ₂ S) and phosphorus sulfide (for example, diphosphorus pentasulfide (P ₂ S ₅ )), [2] lithium sulfide and at least one of simple phosphorus and simple sulfur, Alternatively, [3] It can be produced by a reaction of lithium sulfide, phosphorus sulfide (for example, diphosphorus pentasulfide (P ₂ S ₅ )) and at least one of simple phosphorus and simple sulfur.

The ratio of Li ₂ S to P ₂ S ₅ in the Li—PS glass and Li—PS glass ceramics is a molar ratio of Li ₂ S: P ₂ S ₅ , preferably 65:35 to 35:35. 85:15, more preferably 68:32 to 77:23. By setting the ratio of Li ₂ S to P ₂ S ₅ within this range, the lithium ion conductivity can be further increased. Specifically, the lithium ion conductivity can be preferably 1 × 10 ⁻⁴ S / cm or more, more preferably 1 × 10 ⁻³ S / cm or more. Although there is no upper limit in particular, it is practical that it is 1 * 10 < ^-1 > S / cm or less.

Specific examples of the compound of the sulfide-based inorganic solid electrolyte include, for example, those using a raw material composition containing Li ₂ S and a sulfide of an element belonging to Group 13 to Group 15. it can. More _{specifically, Li 2 S-P 2 S} 5, Li 2 S-LiI-P 2 S 5, Li 2 S-LiI-Li 2 O-P 2 S 5, Li 2 S-LiBr-P 2 S _{5, Li 2 S-Li 2} O-P 2 S 5, Li 2 S-Li 3 PO 4 -P 2 S 5, Li 2 S-P 2 S 5 -P 2 O 5, Li 2 S-P 2 S _{5 -SiS 2, Li 2 S-} P 2 S 5 -SnS, Li 2 S-P 2 S 5 -Al 2 S 3, Li 2 S-GeS 2, Li 2 S-GeS 2 -ZnS, Li 2 S- _{Ga 2 S 3, Li 2 S} -GeS 2 -Ga 2 S 3, Li 2 S-GeS 2 -P 2 S 5, Li 2 S-GeS 2 -Sb 2 S 5, Li 2 S-GeS 2 -Al 2 _{S 3, Li 2 S-SiS} 2, Li 2 S-Al 2 S 3, Li 2 S-SiS 2 - _{l 2 S 3, Li 2 S} -SiS 2 -P 2 S 5, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -Li 4 SiO _4, such as _{Li 2 S-SiS 2 -Li 3} PO 4, Li 10 GeP 2 S 12 and the like. Among them, Li ₂ S—P ₂ S ₅ , Li ₂ S—GeS ₂ —Ga ₂ S ₃ , Li ₂ S—SiS ₂ —P ₂ S ₅ , Li ₂ S—SiS ₂ —Li ₄ SiO ₄ , Li _{2 S-SiS 2 -Li 3 PO 4} , Li 2 S-LiI-Li 2 O-P 2 S 5, Li 2 S-Li 2 O-P 2 S 5, Li 2 S-Li 3 PO 4 -P 2 S ₅ , a raw material composition comprising crystalline, amorphous or a mixture of crystalline and amorphous material composed of Li ₂ S—GeS ₂ —P ₂ S ₅ or Li ₁₀ GeP ₂ S ₁₂ has high lithium ion conductivity. This is preferable. Examples of a method for synthesizing a sulfide-based inorganic solid electrolyte material using such a raw material composition include an amorphization method. Examples of the amorphization method include a mechanical milling method and a melt quenching method, and among them, the mechanical milling method is preferable. This is because processing at room temperature is possible, and the manufacturing process can be simplified.
Among these, Li ₂ S—P ₂ S ₅ , Li ₂ S—SiS ₂ —P ₂ S ₅ , Li ₂ S—Li ₂ O—P ₂ S _5, Li ₁₀ GeP ₂ S ₁₂ or the like is preferable.

(Ii) Oxide-based inorganic solid electrolyte The oxide-based inorganic solid electrolyte contains an oxygen atom (O) and has ionic conductivity of a metal element belonging to Group 1 or Group 2 of the periodic table, And what has electronic insulation is preferable.
The oxide-based inorganic solid electrolyte preferably has an ionic conductivity of 1 × 10 ⁻⁶ S / cm or more, more preferably 5 × 10 ⁻⁶ S / cm or more, and 1 × 10 ⁻⁵ S. / Cm or more is particularly preferable. Although there is no particular upper limit, it is practical that it is 1 × 10 ⁻² S / cm or less.

As a specific compound example, for example, Li _xa La _ya TiO ₃ [xa satisfies 0.3 ≦ xa ≦ 0.7, and ya satisfies 0.3 ≦ ya ≦ 0.7. (LLT); Li _xb La _yb Zr _zb M ^bb _{mb Onb} (M ^bb is one or more elements selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In and Sn) Xb satisfies 5 ≦ xb ≦ 10, yb satisfies 1 ≦ yb ≦ 4, zb satisfies 1 ≦ zb ≦ 4, mb satisfies 0 ≦ mb ≦ 2, nb satisfies 5 ≦ nb ≦ 20 Li _xc B _yc M ^cc _{zc Onc} (M ^cc is one or more elements selected from C, S, Al, Si, Ga, Ge, In and Sn. Xc is 0 ≦ xc ≦ 5 Yc satisfies 0 ≦ yc ≦ 1, zc satisfies 0 ≦ zc ≦ 1, and nc satisfies 0 ≦ nc ≦ 6); Li _xd (Al, Ga) _yd (Ti, Ge) _zd Si _ad P _{md Ond} (xd satisfies 1 ≦ xd ≦ 3, yd Satisfies 0 ≦ yd ≦ 1, zd satisfies 0 ≦ zd ≦ 2, ad satisfies 0 ≦ ad ≦ 1, md satisfies 1 ≦ md ≦ 7, and nd satisfies 3 ≦ nd ≦ 13.) ^{_{; Li (3-2xe) M ee xe}} D ee O (xe represents a number of 0 to ^{0.1, M ee} is ^{.D ee} halogen atom or two or more halogen atoms representing a divalent metal atom Li _xf Si _yf O _zf (xf satisfies 1 ≦ xf ≦ 5, yf satisfies 0 <yf ≦ 3, and zf satisfies 1 ≦ zf ≦ 10); Li _xg S _yg O _zg (xg satisfies 1 ≦ xg ≦ 3, yg satisfies 0 <yg ≦ 2, and zg satisfies 1 ≦ zg ≦ 10); Li ₃ BO ₃ ; Li ₃ BO ₃ —Li ₂ SO ₄ ; _{Li 2 O-B 2 O 3} -P 2 O 5; Li 2 O-SiO 2 _{Li 6 BaLa 2 Ta 2 O 12} ; Li 3 PO (4-3 / 2w) N w (w is _{w <1); LISICON Li 3.5} Zn 0.25 GeO with (Lithium super ionic conductor) type crystal structure ₄ ; La _0.55 Li _0.35 TiO ₃ having a perovskite-type crystal structure; LiTi ₂ P ₃ O ₁₂ having a NASICON (Natrium super ionic conductor) type crystal structure; Li _{1 + xh + yh} (Al, Ge) _xh (Ti, Ge) _2-xh Si _yh P _3-yh O ₁₂ (xh satisfies 0 ≦ xh ≦ 1 and yh satisfies 0 ≦ yh ≦ 1) Or; Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ) having a garnet-type crystal structure.
A phosphorus compound containing Li, P and O is also desirable. For example, lithium phosphate (Li ₃ PO ₄ ); LiPON in which a part of oxygen of lithium phosphate is replaced with nitrogen; or; LiPOD ¹ (D ¹ is preferably Ti, V, Cr, Mn, Fe, Co, And at least one element selected from Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au.
Furthermore, LiA ¹ ON (A ¹ is one or more elements selected from Si, B, Ge, Al, C, and Ga) can be preferably used.
Among them, LLT, Li _xb La _yb Zr _zb M ^bb _{mb Onb} (M ^bb , xb, yb, zb, mb and nb are as described above), LLZ, Li ₃ BO ₃ , Li ₃ BO ₃ -Li ₂ SO _{4, or, Li xd (Al, Ga)} yd (Ti, Ge) zd Si ad P md O nd (xd, yd, zd, ad, md and nd are as defined above.) is preferable.

  The inorganic solid electrolyte is preferably a particle. The volume average particle diameter of the particulate inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.1 μm or more. As an upper limit, it is preferable that it is 100 micrometers or less, and it is more preferable that it is 50 micrometers or less. In addition, the measurement of the volume average particle diameter of an inorganic solid electrolyte is performed in the following procedures. The inorganic solid electrolyte particles are prepared by diluting a 1% by weight dispersion in water (heptane in the case of a substance unstable to water) in a 20 mL sample bottle. The diluted dispersion sample is irradiated with 1 kHz ultrasonic waves for 10 minutes and used immediately after that. Using this dispersion sample, using a laser diffraction / scattering particle size distribution measuring device LA-920 (trade name, manufactured by HORIBA), data acquisition was performed 50 times using a quartz cell for measurement at a temperature of 25 ° C. Obtain the volume average particle size. For other detailed conditions and the like, refer to the description of JISZ8828: 2013 “Particle Size Analysis—Dynamic Light Scattering Method” as necessary. Five samples are prepared for each level, and the average value is adopted.

The content of the inorganic solid electrolyte in the solid electrolyte composition is preferably 5% by mass or more at a solid content of 100% by mass, considering both battery performance, reduction in interface resistance and a maintenance effect. The content is more preferably at least 90% by mass, and particularly preferably at least 90% by mass. As an upper limit, it is preferable that it is 99.9 mass% or less from the same viewpoint, It is more preferable that it is 99.5 mass% or less, It is especially preferable that it is 99 mass% or less.
However, when the positive electrode active material or the negative electrode active material is contained, the content of the inorganic solid electrolyte in the solid electrolyte composition is such that the total content of the positive electrode active material or the negative electrode active material and the inorganic solid electrolyte is in the above range. Is preferred.
In this specification, solid content means the component which does not lose | disappear by volatilizing thru | or evaporating, when a drying process is performed at 170 degreeC for 6 hours. Typically, it refers to components other than the dispersion medium described below.
An inorganic solid electrolyte may be used individually by 1 type, or may be used in combination of 2 or more type.

[Polymer binder]
The solid electrolyte composition of the present invention contains a polymer binder.
The polymer binder only needs to contain a branched polymer, which will be described later, and may contain other components and various additives in addition to this. As other components, it is preferable to contain a metal salt or a molten salt containing ions of metal elements belonging to Group 1 or Group 2 of the Periodic Table.

(I) Branched polymer The branched polymer has three or more polymerization initiator residues of the polymer molecule at the terminal of the polymer molecule. By using this branched polymer in combination with an inorganic solid electrolyte and further an active material, the above-described excellent effects can be imparted to a solid electrolyte composition containing them.
In the present invention, the term “branched” means a state in which side chains are connected between polymer main chains to form branches. In such a branched polymer, the main chain of the polymer molecule refers to a molecular chain that is formed in a chain by the initiation of the (polymerization) reaction of the monomer component by the polymerization initiator. It refers to the element to which the residue of the initiator is linked and the last element of the molecular chain formed from this chain.
Residue of polymerization initiator (polymerization initiator residue) is a partial structure in which a radical portion generated by cleavage of a polymerization initiator used for polymerization (production) of a branched polymer is bonded to the end of a polymer molecule, etc. (Group, not radical). Accordingly, the polymerization initiator residue has a partial structure of the polymerization initiator and has no polymerization initiating action. Moreover, a polymerization initiator residue shows interaction with said solid particle. When paying attention to this point, it is preferable to have a polar substituent having an oxygen atom, a nitrogen atom or a sulfur atom, which has an adsorption interaction by solid particles and van der Waals force. In this respect, the polymerization initiator residue can also be referred to as an adsorptive group for the solid particles.
The details of the polymerization initiator residue will be described later.

  The main chain of the branched polymer is not particularly limited, and examples thereof include a polyalkylene chain (derived from (meth) acrylate) which may have a substituent, a polyamide chain, a polyester chain, and a polyether chain. Derived from the monomer described below. Among these, a polyalkylene chain is preferable.

The branched polymer has a linking group. The linking group refers to a divalent or higher valent substituent that links the polymers forming the main chain.
This linking group may be present in the main chain of the branched polymer, and may be present in the side chain by bonding directly to the atom forming the main chain or via another atom or group. . Preferably, it is an embodiment having a side chain by bonding to an atom forming the main chain via another group. In this embodiment, the linking group can also be referred to as a group linking polymerizable groups in the monomer described later.
The linking group preferably contains at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom and a silicon atom. Each of these heteroatoms has a valence of 2 or more, and the valence in the linking group is not particularly limited, and may be trivalent, tetravalent, hexavalent or the like depending on the atom. The linking group usually has these heteroatoms, carbon atoms and hydrogen atoms.
Among the above, the hetero atom selected from the above group contained in the linking group is preferably an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom, and more preferably an oxygen atom.
The number of heteroatoms selected from the above group contained in the linking group may be at least one, preferably 1 to 40, and more preferably 2 to 30. The total number of atoms constituting the linking group is not particularly limited, but is preferably 1 to 200, and more preferably 4 to 150. Preferred combinations of atoms (excluding hydrogen atoms) forming a linking group include carbon atom-oxygen atom, carbon atom-nitrogen atom, carbon atom-sulfur atom, oxygen atom-silicon atom, oxygen atom-sulfur atom, oxygen atom. -A phosphorus atom, a carbon atom-a nitrogen atom-an oxygen atom etc. are mentioned.

The linking group is preferably a divalent or higher valent group, and may be an ion conductive group or a non-ion conductive group. Specific examples include groups in which one or more hydrogen atoms have been further removed from each group contained in the substituent Z described later. Examples thereof include a linking group containing an alkylene group, an alkanetriyl group, an arylene group, or a heterocyclic group. Examples of the linking group include a linking group including a carbonate group, an ester group, an amide group, a thiocarbonate group, a thioester group, a sulfide group, an alkylene oxide group, a phosphate group, a silane group, or a siloxane group. Among them, an ion conductive group is preferable, and specifically, selected from the group consisting of a carbonate group, an ester group, an amide group, a thiocarbonate group, a thioester group, an alkylene oxide group, a phosphate group, a silane group, and a siloxane group. A linking group containing at least one group is preferred. When the solid electrolyte composition contains an active material, the ionic conductivity is improved because the main chain or the linking group of the branched polymer covers the active material. In this respect, the linking group is more preferably a group containing an alkylene oxide group, a carbonate group, an ester group, a thioester group, a sulfide group or a siloxane group, more preferably a group containing an alkylene oxide group, a carbonate group or a siloxane group, A group containing an alkylene oxide group is particularly preferred.
Here, the “linking group containing an XX group” includes a linking group consisting of at least one XX group, a linking group consisting of at least one XX group, another group, and the like. Examples of other groups include groups derived from monomers described later, such as a carbonyl group and a carbonyloxy group.

The amide group includes a —CO—NR— group or a —CO—N <group. Here, R represents a substituent, and is preferably selected from the substituent Z described later. The thiocarbonate group is a -S-CO-O- group, -O-CO-S- group, -O-CS-O- group, -S-CS-O- group, -O-CS-S- group or Includes -S-CS-S- group. The thioester group includes a -CS-O- group, a -CO-S- group, or a -CS-S- group (also referred to as a dithioester group). The alkylene group in the alkylene oxide group is preferably an alkylene group having 1 to 14 carbon atoms, more preferably an alkylene group having 1 to 10 carbon atoms, and particularly preferably 1 to 4 carbon atoms. The silane group is a group represented by —SiR ₂ — (R represents a substituent). The siloxane group is a group represented by — (SiR ₂ —O) — (R represents a substituent).

Each of the above groups has a valence of 2 or more, and the valence in the linking group can be trivalent or tetravalent.
The linking group may consist of one group as described above, or may be a combination of two or more. The number to combine is not specifically limited, For example, 2-6 pieces are preferable and 2-3 pieces are more preferable. In this case, preferable combinations include ester group-alkylene oxide group, amide group-alkylene oxide group, carbonate group-alkylene oxide group, ester group-siloxane group, amide group-siloxane group, carbonate group-siloxane group, ester group- Examples thereof include a sulfide group or a carbonate group-sulfide group.

  In the present invention, it is preferable to have a repeating unit (structure) as a linking group. In particular, it preferably has an oligo (poly) alkylene oxide group or an oligo (poly) siloxane group. When it has an alkylene oxide group as a repeating unit, an ester group-oligo (poly) alkylene oxide group-carbonyl group, and when it has a siloxane group, an ester group-oligo (poly) dimethylsiloxane group-carbonyl group, etc. are exemplified. .

  The branched polymer has three or more polymerization initiator residues at its ends. The number of residues is defined by the weight average molecular weight of the polymer and the molar amount of initiator residues. Thereby, binding property between solid particles etc. can be improved. In this respect, the branched polymer preferably has 4 or more polymerization initiator residues, more preferably 5 or more, and still more preferably 6 or more. On the other hand, the branched polymer has a polymerization initiator residue of preferably 100 or less, more preferably 80 or less, and even more preferably 50 or less, because it inhibits lithium ion conduction if the solid particles are covered too much.

The polymerization initiator residue is preferably a partial structure (residue) of at least one of a thermal radical polymerization initiator and a chain transfer agent, which will be described later, and a partial structure (residual) of the thermal radical polymerization initiator. More preferably, it is a group). Here, the partial structure of the polymerization initiator is a partial structure (group) formed by bonding a radical part generated by cleavage of the polymerization initiator to the end of the polymer molecule, and the polymer and polymerization initiator in the polymerization reaction are cleaved. The structure (group) formed by the reaction of the radical part generated by the reaction with the chain transfer agent and the radical part of the chain transfer agent bonded to the end of the polymer molecule.
1 type, 2 or more types may be sufficient as the polymerization initiator residue which a branched polymer has, and when it is 2 or more types, they may mutually differ.

The polymerization initiator residue is not particularly limited as long as it is a monovalent group derived from the polymerization initiator, but is a cyano group or an ester group (-) in that the binding property (interaction) to the inorganic solid electrolyte is strong. COOR: R represents a substituent, and preferably includes at least one group selected from the group consisting of a heterocyclic group, an amidine group, an acyl group, an amide group, an alkoxy group and a sulfide group.
Examples of the heterocyclic group include the heterocyclic groups mentioned in Substituent Z described later, preferably a nitrogen-containing heterocyclic group, more preferably an imidazole ring group, a pyrazole ring group, an imidazoline ring group, or a pyrrole ring group, and an imidazole ring. The group is particularly preferred.
An amidine group is a group obtained by removing one hydrogen atom from an amidine compound represented by R ¹ —C (═NR ² ) —NR ³ R ⁴ . R ¹ is an alkyl group or an aryl group, R ² is an alkyl group, an aryl group or a hydrogen atom, R ³ is an alkyl group, an aryl group or a hydrogen atom, and R ⁴ is an alkyl group, an aryl group or a hydrogen atom. It is. Preferably, R ¹ is an alkyl group, R ² is a hydrogen atom or an alkyl group, R ³ is an alkyl group or a hydrogen atom, and R ⁴ is an alkyl group or a hydrogen atom. Both the alkyl group and the aryl group may be further substituted.

The polymerization initiator residue is preferably one represented by any of the following formulas (S1) to (S7).
In each formula, * represents a linking site with the end of the polymer molecule.

In the formula, L represents a divalent linking group. Examples of the linking group include an alkylene group and an arylene group. The linking group L may have a substituent. The substituent that may be included is not particularly limited, and examples thereof include each group included in the substituent Z described later, or the ester group, carboxylic acid group, or siloxane group described above. Among these, an alkyl group, an ester group, a carboxylic acid group, a cyano group, an alkoxy group, or a siloxane group (for example, an alkyl, aryl, alkoxy, or aryloxysilyl group) is preferable. Among the above, the linking group is preferably an alkylene group, and is preferably an isopropylene group. The isopropylene group may be further substituted or may form a ring.
Each of n ^{s11 to} n ^s51 represents the number of linking groups L in each formula, and each independently represents an integer of 0 to 10. Each of n ^{s11 to} n ^s51 is preferably an integer of 1 to 5, and more preferably 1.

X represents an oxygen atom or a sulfur atom each independently, and an oxygen atom is preferable.
In the formula (S1), two Xs may be the same or different, and both are preferably oxygen atoms.

R ^s11 , R ^s21 , R ^s41 , R ^s42 , R ^s61 and R ^s71 each independently represent a monovalent substituent. It does not specifically limit as a substituent, Each group contained in the substituent Z mentioned later is mentioned.
R ^s11 , R ^s61 and R ^s71 are each preferably an alkyl group or an aryl group. The alkyl group is not particularly limited, and preferably has 1 to 16 carbon atoms. The aryl group is not particularly limited, and preferably has 6 to 24 carbon atoms.
R ^s21 , R ^s41, and R ^s42 are each preferably a hydrogen atom, an alkyl group, or an aryl group, and more preferably a hydrogen atom or an alkyl group. The alkyl group is not particularly limited, and preferably has 1 to 16 carbon atoms. The aryl group is not particularly limited, and preferably has 6 to 24 carbon atoms.
In the formula (S2), two R ^s21 may be the same or different. A ring may be formed. In the formula (S4), two R ^{s41 s} may be the same or different. A ring may be formed.
R ^s11 , R ^s21 , R ^s41 , R ^s42 , R ^s61, and R ^s71 may each have a substituent. The substituent that may be included is not particularly limited, and examples thereof include each group included in the substituent Z described later, or the above-described siloxane group or alkylene oxide group. Among these, an alkyl group, an aryl group, a siloxane group, or an alkylene oxide group is preferable.

Q ^s5 represents a heterocyclic ring containing -C = N-. Such a nitrogen-containing heterocyclic ring is not particularly limited, and examples thereof include an imidazole ring, a pyrazole ring, an imidazoline ring, and a pyrrole ring. Among these, an imidazole ring is preferable.

The residues represented by the above formulas (S1) to (S5) are preferably residues represented by the following formulas (S1B) to (S5B), respectively.
In each formula, * represents a linking site with the end of the polymer molecule.

  In the formula, X represents an oxygen atom or a sulfur atom, and is synonymous with X in the above formulas (S1) and (S2), and preferred ones are also the same.

^{R s11,} R s21, R ^s41 and ^{R s42} each independently represent a monovalent substituent, the above formula ^{(S1), R s11, R} s21, R s41 and ^{R s42} of (S2) and (S4) Are the same as each other, and the preferred ones are also the same.
R ^s13 , R ^s14 , R ^s23 , R ^s24 , R ^s33 , R ^s34 , R ^s43 , R ^s44 , R ^s53 and R ^s54 each independently represent a monovalent substituent. It does not specifically limit as a substituent, Each group contained in the substituent Z mentioned later is mentioned.
^{R s13, R s14, R s23} , R s24, R s33, R s34, R s43, R s44, R s53 and ^{R s54} each an alkyl group or an aryl group and more preferably an alkyl group. The alkyl group is not particularly limited and preferably has 1 to 16 carbon atoms, more preferably 1 to 12 carbon atoms, and the aryl group is not particularly limited and has 6 to 6 carbon atoms. 24 is preferable. R ^s13 and R ^s14 , R ^s23 and R ^s24 , R ^s33 and R ^s34 , R ^s43 and R ^s44 , and R ^s53 and R ^s54 may be the same or different.
R ^s13 , R ^s14 , R ^s23 , R ^s24 , R ^s33 , R ^s34 , R ^s43 , R ^s44 , R ^s53, and R ^s54 may each have a substituent. The substituent that may be included is not particularly limited, and examples thereof include each group included in the substituent Z described later, or the ester group, carboxylic acid group, and siloxane group described above. Among these, an ester group, a carboxylic acid group, a cyano group, an alkoxy group, or a siloxane group is preferable.

Q ^s5 represents a heterocyclic ring containing ^—C═N—, and is synonymous with Q ^{s5 in the} above formula (S5), and preferred ones are also the same.

  In the present invention, the polymerization initiator residue is preferably a residue represented by the formula (S1), (S2), (S3) or (S7) among the above formulas, and the formula (S1), (S3) or The residue represented by (S7) is more preferred, and the residue represented by formula (S1B), (S3B) or (S7) is more preferred.

  In the branched polymer, the combination of the linking group, the main chain, and the polymerization initiator residue is not particularly limited, and can be appropriately combined. A preferable combination is a combination of a preferable linking group, a preferable main chain, and a preferable polymerization initiator residue.

In the branched polymer, the number of moles [Bn] of linking groups (not the linking group L in the above formulas) contained in the polymer molecule and the number of moles [Bs] of the polymerization initiator residue are [Bs]. /[Bn]≧0.1 is preferably satisfied. When the molar ratio [Bs] / [Bn] is 0.1 or more, it is considered that the polymerization initiator residue is sufficiently adsorbed on the solid particles, and a good solid-solid interface is formed.
The molar ratio [Bs] / [Bn] is preferably 0.1 or more, more preferably 0.5 or more, and still more preferably 1 or more in the above points. On the other hand, the molar ratio [Bs] / [Bn] is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less, from the viewpoint of increasing the interfacial resistance by covering the solid particles too much.
The number of moles [Bn] of the linking group and the number of moles [Bs] of the polymerization initiator residue can be calculated by measuring ¹ H-NMR of the branched polymer.
The molar ratio [Bs] / [Bn] can be appropriately set depending on the amount of the polymerization initiator used, selecting the type of monomer described later (those having different linking groups), reaction temperature, and the like.

The weight average molecular weight of the branched polymer is preferably 1000 to 300,000. When the branched polymer has a mass average molecular weight of 1,000 to 300,000, it is easy to dissolve in a composition together with a solvent, and handling is good. Furthermore, since it has stretchability as a material forming a solid interface, it works well on battery characteristics such as cycle characteristics. In this respect, the mass average molecular weight is more preferably 1000 to 200000, further preferably 1500 to 200000, and particularly preferably 2000 to 150,000.
In the present invention, the molecular weight of the polymer means a mass average molecular weight unless otherwise specified. The mass average molecular weight can be measured as a molecular weight in terms of polystyrene by gel permeation chromatography (GPC). Specifically, the measurement is performed according to the measurement method and conditions in Examples described later.

  When the crosslinking of the polymer proceeds by heating or voltage application, the molecular weight may be larger than the above molecular weight. Preferably, the polymer has a weight average molecular weight in the above range at the start of use of the all-solid secondary battery.

The water concentration of the branched polymer used in the present invention is preferably 100 ppm (mass basis) or less.
The branched polymer used in the present invention may be crystallized and dried, or the polymer solution may be used as it is.

  When the branched polymer is a particle, the average particle size thereof is 50,000 nm or less, more preferably 10,000 nm or less, further preferably 5000 nm or less, further preferably 3000 nm or less, more preferably 1000 nm. It is particularly preferred that The lower limit is 10 nm or more, preferably 30 nm or more, more preferably 50 nm or more, and particularly preferably 100 nm or more. By setting the size of the branched polymer particles in the above range, the area of the resistance film with the solid particles or the like can be reduced, and the resistance can be reduced. That is, good adhesion and suppression of interface resistance can be realized.

Unless otherwise specified, the average particle size of the branched polymer particles is determined according to the measurement conditions and definitions described below.
A 1% by mass dispersion of the branched polymer particles is prepared in a 20 mL sample bottle using an appropriate solvent (an organic solvent used for preparing the solid electrolyte composition, for example, heptane). The diluted dispersion sample is irradiated with 1 kHz ultrasonic waves for 10 minutes and used immediately after that. Using this dispersion sample, using a laser diffraction / scattering particle size distribution measuring device LA-920 (trade name, manufactured by HORIBA), data acquisition was performed 50 times using a quartz cell for measurement at a temperature of 25 ° C. Let the obtained volume average particle diameter be the average particle diameter. For other detailed conditions and the like, refer to the description of JISZ8828: 2013 “Particle Size Analysis—Dynamic Light Scattering Method” as necessary. Five samples are prepared for each level and measured, and the average value is adopted.
When using an all-solid secondary battery, for example, after disassembling the all-solid secondary battery and peeling off the active material layer or the solid electrolyte layer, the average particle diameter of the branched polymer particles for the material is measured. The measurement can be performed according to the method, and the measurement of the average particle diameter of particles other than the branched polymer particles, which has been measured in advance, can be excluded.

One type or two or more types of branched polymers can be used.
The content of the branched polymer in the polymer binder is not particularly limited, and is 0.1% in terms of ionic conductivity and binding properties, and interfacial resistance between solid particles at a solid content of 100% by mass. It is preferably at least mass%, more preferably at least 0.5 mass%, particularly preferably at least 1 mass%. The upper limit is preferably 100% by mass, more preferably 50% by mass or less, and particularly preferably 30% by mass or less from the same point.

In the present specification, the indication of a compound (for example, when referring to a compound with a suffix) is used to mean that the compound itself, its salt, and its ion are included. In addition, it is meant to include derivatives in which a part thereof is changed, such as introduction of a substituent, within a range where a desired effect is exhibited.
In the present specification, a substituent that does not specify substitution / non-substitution (the same applies to a linking group) means that the group may have an appropriate substituent. This is also synonymous for compounds that do not specify substitution or non-substitution. Preferred substituents include the following substituent Z.
Further, in the present specification, when simply described as XXX group, the XXX group is selected from the following substituents Z corresponding to this group.

Examples of the substituent Z include the following.
An alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl A group (preferably an alkenyl group having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), an alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, such as ethynyl, butadiynyl, phenylethynyl, etc.), A cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc., but in this specification, an alkyl group usually means a cycloalkyl group) ), An aryl group (preferably An aryl group having 6 to 26 atoms, such as phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc., a heterocyclic group (preferably a heterocyclic group having 2 to 20 carbon atoms) And preferably a 5- or 6-membered heterocyclic group having at least one oxygen atom, sulfur atom or nitrogen atom, such as tetrahydropyran, tetrahydrofuran, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2- Benzimidazolyl, 2-thiazolyl, 2-oxazolyl, pyrrolidone group, etc.), an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, such as methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), an aryloxy group (preferably An aryloxy group having 6 to 26 carbon atoms, such as phenoxy, -Naphtyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc., but the term “alkoxy group” in the present specification usually includes an aryloyl group), an alkoxycarbonyl group (preferably an alkoxycarbonyl having 2 to 20 carbon atoms) A group such as ethoxycarbonyl, 2-ethylhexyloxycarbonyl, etc., an aryloxycarbonyl group (preferably an aryloxycarbonyl group having 6 to 26 carbon atoms such as phenoxycarbonyl, 1-naphthyloxycarbonyl, 3-methylphenoxycarbonyl) 4-methoxyphenoxycarbonyl, etc.), an amino group (preferably containing an amino group having 0 to 20 carbon atoms, an alkylamino group, an arylamino group, such as amino, N, N-dimethylamino, N, N-diethyla Mino, N-ethylamino, anilino, etc.), a sulfamoyl group (preferably a sulfamoyl group having 0 to 20 carbon atoms, such as N, N-dimethylsulfamoyl, N-phenylsulfamoyl etc.), an acyl group (preferably Is an acyl group having 1 to 20 carbon atoms, such as acetyl, propionyl, butyryl, etc., an aryloyl group (preferably an aryloyl group having 7 to 23 carbon atoms, such as benzoyl, etc. Usually means an aryloyl group. ), An acyloxy group (preferably an acyloxy group having 1 to 20 carbon atoms such as acetyloxy), an aryloyloxy group (preferably an aryloyloxy group having 7 to 23 carbon atoms such as benzoyloxy, etc. In this specification, an acyloxy group usually means an aryloyloxy group), a carbamoyl group (preferably a carbamoyl group having 1 to 20 carbon atoms, such as N, N-dimethylcarbamoyl, N-phenylcarbamoyl, etc. ), An acylamino group (preferably an acylamino group having 1 to 20 carbon atoms such as acetylamino, benzoylamino, etc.), an alkylthio group (preferably an alkylthio group having 1 to 20 carbon atoms such as methylthio, ethylthio, isopropylthio) , Benzylthio, etc.), Ally A thio group (preferably an arylthio group having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.), an alkylsulfonyl group (preferably having 1 to 20 carbon atoms) An alkylsulfonyl group such as methylsulfonyl and ethylsulfonyl; an arylsulfonyl group (preferably an arylsulfonyl group having 6 to 22 carbon atoms such as benzenesulfonyl); and an alkylsilyl group (preferably having 1 to 20 carbon atoms). Alkylsilyl groups such as monomethylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl, etc., arylsilyl groups (preferably arylsilyl groups having 6 to 42 carbon atoms such as triphenylsilyl), alkoxysilyl groups (preferably Is 1 carbon atom 20 alkoxysilyl groups such as monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl, etc., aryloxysilyl groups (preferably aryloxysilyl groups having 6 to 42 carbon atoms such as triphenyloxysilyl) Etc.), a phosphoryl group (preferably a phosphoryl group having 0 to 20 carbon atoms, such as —OP (═O) (R ^P ) ₂ ), a phosphonyl group (preferably a phosphonyl group having 0 to 20 carbon atoms, for example, _{^{-P (= O) (R P}} ) 2), a phosphinyl group (preferably a phosphinyl group having 0 to 20 carbon atoms, for example, ^-P (R _P) 2), (meth) acryloyl group, (meth) acryloyloxy Group, (meth) acryloylumimino group ((meth) acrylamide group), hydroxy group, mercapto group, carboxy group , Phosphoric acid group, phosphonic acid group, sulfonic acid group, cyano group, halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.).
In addition, each of the groups listed as the substituent Z may be further substituted by the above-described substituent Z.
When a compound or a substituent / linking group includes an alkyl group / alkylene group, an alkenyl group / alkenylene group, an alkynyl group / alkynylene group, etc., these may be cyclic or linear, and may be linear or branched These may be substituted as described above or may be unsubstituted.

(Ii) Metal salt or molten salt The polymer binder preferably contains at least one of a metal salt containing a metal element ion belonging to Group 1 or Group 2 of the periodic table and a molten salt. When the polymer binder contains a metal salt or a molten salt, since the crosslinking density of the branched polymer is high, the ionic conductivity can be further improved, and the battery performance can be further improved. In particular, when the metal salt is a lithium salt, high ion conductivity is exhibited, and higher cycle characteristics, high-temperature storage stability, and low resistance after cycle characteristics can be imparted to the all-solid-state lithium ion secondary battery.

(Ii-1) Metal salt The metal salt is not particularly limited as long as it contains a metal element ion belonging to Group 1 or Group 2 of the Periodic Table. For example, an inorganic lithium salt, a fluorine-containing organic lithium salt, an oxalate borate salt, or the like can be given, and an inorganic lithium salt is preferable. Any of those usually used for secondary batteries can be used without any particular limitation, and for example, those described in paragraphs [0082] to [0085] of JP-A-2015-088486 can be used. This description is preferably incorporated in the present specification as it is. Specifically, LiPF ₆ , LiClO ₄ , LiTFSI, LIFSI, LiBF ₄ , lithium bis (oxalato) rate (Li (C ₂ O ₂ ) ₂ B, LiBOB) and the like are preferably used.

(Ii-2) Molten salt The molten salt is not particularly limited as long as it includes a metal element ion belonging to Group 1 or Group 2 of the Periodic Table.
As the molten salt, for example, a chemical substance (also referred to as an ionic liquid) selected from a compound comprising a combination of the following cation and anion can be used.

Examples of the cation include an imidazolium cation having the following substituents at the 1-position and the 3-position, a pyridinium cation having the following substituent, a piperidinium cation having the following substituent, and a pyrrolidinium cation having the following substituent. And phosphonium cations having the following substituents or quaternary ammonium cations having the following substituents.
As the cation, these cations can be used alone or in combination of two or more.
Preferably, it is an imidazolium cation, a quaternary ammonium cation, a piperidinium cation or a pyrrolidinium cation, more preferably an imidazolium cation, a quaternary ammonium cation or a pyrrolidinium cation, still more preferably a quaternary ammonium cation. Or a pyrrolidinium cation.
Examples of the substituent include an alkyl group (preferably having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms), a hydroxyalkyl group (preferably having 1 to 3 carbon atoms), an ether group, an allyl group, and an aminoalkyl group. (Preferably having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms) and aryl groups (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms). The substituent may form a cyclic structure containing a cation moiety. The substituent may further have a substituent Z described later.

Anions include chloride ion, bromide ion, iodide ion, boron tetrafluoride ion, nitrate ion, dicyanamide ion, acetate ion, iron tetrachloride ion, bis (trifluoromethanesulfonyl) imide ion, bis (fluorosulfonyl) imide ion Bis (perfluorobutylmethanesulfonyl) imide ion, hexafluorophosphate ion, or trifluoromethanesulfonate ion.
As anions, these anions can be used alone or in combination of two or more.
Preferred are chloride ion, bromide ion, boron tetrafluoride ion, nitrate ion, dicyanamide ion, bis (trifluoromethanesulfonyl) imide ion or bis (fluorosulfonyl) imide ion or hexafluorophosphate ion, more preferably Boron tetrafluoride ion, bis (trifluoromethanesulfonyl) imide ion, bis (fluorosulfonyl) imide ion or hexafluorophosphate ion, more preferably bis (trifluoromethanesulfonyl) imide ion or bis (fluorosulfonyl) imide ion.

  Examples of the ionic liquid include 1-allyl-3-ethylimidazolium bromide, 1-ethyl-3-methylimidazolium bromide, 1- (2-hydroxyethyl) -3-methylimidazolium bromide, 1- ( 2-methoxyethyl) -3-methylimidazolium bromide, 1-octyl-3-methylimidazolium chloride, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate, ethylmethyl Imidazolium bis (trifluoromethanesulfonyl) imide, ethylmethylimidazolium bistrifluoromethanesulfonic acid, ethylmethylimidazolium dicyanamide, 1-butyl-1-methylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-3 -Methyli Dazolium bis (trifluoromethanesulfonyl) imide, trimethylbutylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide, N- (2 -Methoxyethyl) -N-methylpyrrolidinium tetrafluorobollard, 1-butyl-1-methylpyrrolidinium imidazolium bis (fluorosulfonyl) imide, (2-acryloylethyl) trimethylammonium bis (trifluoromethanesulfonyl) imide, Or a trihexyl tetradecyl phosphonium chloride etc. are mentioned.

  A metal salt and a molten salt can be used in combination. In this case, the combination of the metal salt and the molten salt is not particularly limited, and can be appropriately set depending on the purpose.

  The (total) content of the metal salt or molten salt in the polymer binder is not particularly limited, and is preferably 5% by mass or more in terms of ionic conductivity at a solid content of 100% by mass. % Or more is more preferable, and 20% by mass or more is particularly preferable. The upper limit is preferably 80% by mass or less, more preferably 70% by mass or less, and particularly preferably 50% by mass or less, since the ionic conductivity is lowered because the fluidity is deteriorated.

  In the polymer binder, the mass ratio of the content is not particularly limited as long as the content of the branched polymer and the content of the metal salt or molten salt are within the above ranges, respectively. For example, the mass ratio of the content of the metal salt or the molten salt to the content of the branched polymer is preferably 0.5 to 50, and more preferably 1 to 40.

  When the polymer binder contains a branched polymer and other components other than the metal salt or molten salt and various additives, these components are not particularly limited as long as they do not impair the object of the present invention. Examples of other components include polymers other than branched polymers. The content of each of these components is appropriately determined.

In the present invention, the content of the polymer binder in the solid electrolyte composition is preferably 0.1% by mass or more at a solid content of 100% by mass in terms of ionic conductivity and binding properties, and 0.5% by mass. % Or more is more preferable, and 1 mass% or more is more preferable. In the same point, the upper limit is preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 10% by mass or less.
In the present invention, the branched polymer exhibits a strong binding property to the solid particles. Therefore, the content of the polymer binder in the solid electrolyte composition can be reduced. For example, the content of the polymer binder can be 0.1 to 5% by mass, preferably 0.2 to 2% by mass, at a solid content of 100% by mass.

In the solid electrolyte composition of the present invention, the mass ratio [A + E] / [B] of the total content [A + E] of the inorganic solid electrolyte and the electrode active material described later with respect to the content [B] of the polymer binder is: Although not particularly limited, a range of 1,000 to 1 is preferable. When the mass ratio [A + E] / [B] is in the range of 1,000 to 1, both good binding properties and battery performance can be achieved.
This mass ratio [A + E] / [B] is more preferably in the range of 500 to 3, more preferably in the range of 100 to 5, in terms of the above points.

[Dispersion medium]
The solid electrolyte composition of the present invention preferably contains a dispersion medium.
The dispersion medium only needs to disperse each of the above components, and examples thereof include various organic solvents. Specific examples of the dispersion medium include the following.
Examples of the alcohol compound solvent include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-butanol, ethylene glycol, propylene glycol, glycerin, 1,6-hexanediol, cyclohexanediol, sorbitol, xylitol, Examples include 2-methyl-2,4-pentanediol, 1,3-butanediol, and 1,4-butanediol.
Examples of ether compound solvents include alkylene glycol alkyl ethers (ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol, dipropylene glycol, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol, polyethylene glycol, propylene glycol monomethyl ether, dipropylene. Glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether, etc.), dialkyl ethers (dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, etc.), cyclic ethers (tetrahydrofuran, geo Sun (1,2, including 1,3- and 1,4-isomers of), etc.).
Examples of the amide compound solvent include N, N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, 2-pyrrolidinone, ε-caprolactam, formamide, N -Methylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropanamide, hexamethylphosphoric triamide and the like.
Examples of the amino compound solvent include triethylamine, diisopropylethylamine, tributylamine and the like.
Examples of the ketone compound solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.
Examples of the aromatic compound solvent include benzene, toluene, xylene and the like.
Examples of the aliphatic compound solvent include hexane, heptane, octane, decane, and the like.
Examples of the nitrile compound solvent include acetonitrile, propyronitrile, isobutyronitrile, and the like.
Examples of the ester compound solvent include ethyl acetate, butyl acetate, propyl acetate, butyl butyrate, and butyl pentanoate.
Examples of the non-aqueous dispersion medium include the above aromatic compound solvents and aliphatic compound solvents.

  In the present invention, among them, an amino compound solvent, an ether compound solvent, a ketone compound solvent, an aromatic compound solvent or an aliphatic compound solvent is preferable, and an ether compound solvent, a ketone compound solvent, an aromatic compound solvent or an aliphatic compound solvent is further included. preferable. In the present invention, it is preferable to further select the specific organic solvent using a sulfide-based inorganic solid electrolyte. By selecting this combination, the functional group active for the sulfide-based inorganic solid electrolyte is not included, so that the sulfide-based inorganic solid electrolyte can be handled stably, which is preferable. In particular, a combination of a sulfide-based inorganic solid electrolyte and an aliphatic compound solvent or an aromatic compound solvent is preferable.

The dispersion medium preferably has a boiling point of 50 ° C. or higher, more preferably 70 ° C. or higher, at normal pressure (1 atm). The upper limit is preferably 250 ° C. or lower, and more preferably 220 ° C. or lower.
The said dispersion medium may be used individually by 1 type, or may be used in combination of 2 or more type.

  In the present invention, the content of the dispersion medium in the solid electrolyte composition can be appropriately set in consideration of the balance between the viscosity of the solid electrolyte composition and the drying load. Generally, 0 mass% or more is preferable in a solid electrolyte composition, 20-99 mass% is more preferable, 30-80 mass% is further more preferable, and 40-60 mass parts is especially preferable.

[Active material]
The solid electrolyte composition of the present invention may contain an active material capable of inserting and releasing ions of metal elements belonging to Group 1 or Group 2 of the periodic table. In the present invention, a solid electrolyte composition containing an active material (positive electrode active material or negative electrode active material) may be referred to as an electrode layer composition (positive electrode layer composition or negative electrode layer composition).

(I) Cathode Active Material The cathode active material that may be contained in the solid electrolyte composition of the present invention is preferably one that can reversibly insert and release lithium ions. The material is not particularly limited as long as it has the above characteristics, and may be a transition metal oxide or an element that can be complexed with Li such as sulfur.
Among these, as the positive electrode active material, it is preferable to use a transition metal oxide, and a transition metal oxide having a transition metal element M ^a (one or more elements selected from Co, Ni, Fe, Mn, Cu, and V). More preferred. In addition, this transition metal oxide includes an element M ^b (an element of the first (Ia) group of the metal periodic table other than lithium, an element of the second (IIa) group, Al, Ga, In, Ge, Sn, Pb, Elements such as Sb, Bi, Si, P, or B) may be mixed. The mixing amount, 0~30mol% is preferred for the amount of the transition metal element ^{M a (100mol%).} What was mixed and synthesize | combined so that the molar ratio of Li / Ma might be 0.3-2.2 is more preferable.
Specific examples of the transition metal oxide include (MA) transition metal oxide having a layered rock salt structure, (MB) transition metal oxide having a spinel structure, (MC) lithium-containing transition metal phosphate compound, (MD And lithium-containing transition metal halogenated phosphoric acid compounds or (ME) lithium-containing transition metal silicate compounds.

(MA) As specific examples of transition metal oxides having a layered rock salt structure, LiCoO ₂ (lithium cobaltate [LCO]), LiNi ₂ O ₂ (lithium nickelate) LiNi _0.85 Co _0.10 Al _0.05 O ₂ (lithium nickel cobalt aluminum oxide [NCA]), LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (nickel manganese lithium cobalt oxide [NMC]), or LiNi _0.5 Mn _0.5 O ₂ (Lithium manganese nickelate).
(MB) As specific examples of transition metal oxides having a spinel structure, LiCoMnO _4, Li ₂ FeMn ₃ O ₈ , Li ₂ CuMn ₃ O ₈ , Li ₂ CrMn ₃ O _8, or Li ₂ NiMn ₃ O ₈ Can be mentioned.
Examples of (MC) lithium-containing transition metal phosphate compounds include olivine-type iron phosphate salts such as LiFePO ₄ or Li ₃ Fe ₂ (PO ₄ ) ₃ , iron pyrophosphates such as LiFeP ₂ O ₇ , LiCoPO _{4, and the} like. And monoclinic Nasicon type vanadium phosphate salts such as Li ₃ V ₂ (PO ₄ ) ₃ (Vanadium Lithium Phosphate).
The (MD) lithium-containing transition metal halogenated phosphate compound, for _example, Li 2 FePO ₄ F such fluorinated phosphorus iron _salt, hexafluorophosphate manganese salt such as Li 2 MnPO ₄ F, _or, Li 2 CoPO ₄ Fluorocobalt phosphate such as F.
Examples of the (ME) lithium-containing transition metal silicate compound include Li ₂ FeSiO ₄ , Li ₂ MnSiO ₄ , and Li ₂ CoSiO ₄ .
In the present invention, a transition metal oxide having a (MA) layered rock salt structure is preferable, and LCO or NMC is more preferable.

  The shape of the positive electrode active material is not particularly limited, but is preferably particulate. The volume average particle diameter (sphere conversion average particle diameter) of the positive electrode active material is not particularly limited. For example, the thickness can be 0.1 to 50 μm. In order to make the positive electrode active material have a predetermined particle size, an ordinary pulverizer or classifier may be used. The positive electrode active material obtained by the firing method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent. The volume average particle diameter (sphere conversion average particle diameter) of the positive electrode active material particles can be measured using a laser diffraction / scattering particle size distribution analyzer LA-920 (trade name, manufactured by HORIBA).

The positive electrode active material may be used alone or in combination of two or more.
When forming the positive electrode active material layer, the mass (mg) (weight per unit area) of the positive electrode active material per unit area (cm ² ) of the positive electrode active material layer is not particularly limited. It can be determined appropriately according to the designed battery capacity.

  Content in a solid electrolyte composition of a positive electrode active material is not specifically limited, 10-95 mass% is preferable in solid content of 100 mass%, 20-90 mass% is more preferable, 30-85 mass is further 50 to 80% by mass is particularly preferable.

(Ii) Negative electrode active material The negative electrode active material that may be contained in the solid electrolyte composition of the present invention is preferably one that can reversibly insert and / or release lithium ions. The material is not particularly limited as long as it has the above characteristics, and is a carbonaceous material, a metal oxide such as tin oxide or silicon oxide, a metal composite oxide, a lithium alloy such as lithium simple substance or lithium aluminum alloy, and , Metals capable of forming an alloy with lithium, such as Sn, Si, and In. Among these, a carbonaceous material or a lithium composite oxide is preferably used from the viewpoint of reliability. Moreover, it is preferable that the metal composite oxide can occlude and / or release lithium. The material is not particularly limited, but preferably contains titanium and / or lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics.

  The carbonaceous material used as the negative electrode active material is a material substantially made of carbon. For example, various synthetics such as petroleum pitch, carbon black such as acetylene black (AB), graphite (natural graphite, artificial graphite such as vapor-grown graphite), PAN (polyacrylonitrile) -based resin, furfuryl alcohol resin, etc. The carbonaceous material which baked resin can be mentioned. Further, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA (polyvinyl alcohol) -based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber, etc. And mesophase microspheres, graphite whiskers, flat graphite and the like.

  These carbonaceous materials can be divided into non-graphitizable carbonaceous (hard carbon) materials and graphite-based carbonaceous materials according to the degree of graphitization. Further, the carbonaceous material preferably has the surface spacing, density, and crystallite size described in JP-A-62-222066, JP-A-2-6856, and 3-45473. The carbonaceous material does not need to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, or the like is used. You can also.

  As the metal oxide and metal composite oxide applied as the negative electrode active material, an amorphous oxide is particularly preferable, and chalcogenite, which is a reaction product of a metal element and an element of Group 16 of the periodic table, is also preferably used. It is done. The term “amorphous” as used herein means an X-ray diffraction method using CuKα rays, which has a broad scattering band having an apex in the region of 20 ° to 40 ° in terms of 2θ values, and is a crystalline diffraction line. You may have. The strongest intensity of crystalline diffraction lines seen from 2 ° to 40 ° to 70 ° is 100 times the diffraction line intensity at the peak of the broad scattering band seen from 2 ° to 20 °. It is preferable that it is 5 times or less, and it is particularly preferable not to have a crystalline diffraction line.

Among the compound group consisting of the above amorphous oxide and chalcogenide, amorphous metal oxides and chalcogenides are more preferable, and elements of Groups 13 (IIIB) to 15 (VB) of the periodic table, Al , Ga, Si, Sn, Ge, Pb, Sb and Bi are used alone or in combination of two or more thereof, and chalcogenides are particularly preferable. Specific examples of preferable amorphous oxides and chalcogenides include, for example, Ga ₂ O ₃ , SiO, GeO, SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₈ i ₂ O ₃ , Bi ₂ O ₄ , SnSiO ₃ , GeS, SnS, SnS ₂ , PbS, PbS ₂ , Sb ₂ S ₃ , Sb ₂ S ₅ , or , it includes the SnSiS _3. Moreover, these may be a complex oxide with lithium oxide, for example, Li ₂ SnO ₂ .

It is also preferable that the negative electrode active material contains a titanium atom. More specifically, Li ₄ Ti ₅ O ₁₂ (lithium titanate [LTO]) is excellent in rapid charge / discharge characteristics due to small volume fluctuations during occlusion and release of lithium ions, and the deterioration of the electrodes is suppressed, and lithium ion secondary. This is preferable in that the battery life can be improved.

  In the present invention, hard carbon or graphite is preferably used, and graphite is more preferably used. In the present invention, the carbonaceous materials may be used singly or in combination of two or more.

  The shape of the negative electrode active material is not particularly limited, but is preferably particulate. The average particle size of the negative electrode active material is preferably 0.1 to 60 μm. In order to obtain a predetermined particle size, a normal pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill or a sieve is preferably used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle diameter, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet. The average particle diameter of the negative electrode active material particles can be measured by the same method as the above-described method for measuring the volume average particle diameter of the positive electrode active material.

  The chemical formula of the compound obtained by the above firing method can be calculated from an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method, and from a mass difference between powders before and after firing as a simple method.

  Examples of the negative electrode active material that can be used in combination with the amorphous oxide negative electrode active material centering on Sn, Si, or Ge include carbon materials that can occlude and / or release lithium ions or lithium metal, lithium, and lithium alloys. Alternatively, a metal that can be alloyed with lithium is preferably used.

  In the present invention, it is preferable to apply a Si-based negative electrode. In general, a Si negative electrode can occlude more Li ions than a carbon negative electrode (graphite, acetylene black, etc.). That is, the amount of Li ion occlusion per unit weight increases. Therefore, the battery capacity can be increased. As a result, there is an advantage that the battery driving time can be extended.

The said negative electrode active material may be used individually by 1 type, or may be used in combination of 2 or more type.
When the negative electrode active material layer is formed, the mass (mg) (weight per unit area) of the negative electrode active material per unit area (cm ² ) of the negative electrode active material layer is not particularly limited. It can be determined appropriately according to the designed battery capacity.

  Content in a solid electrolyte composition of a negative electrode active material is not specifically limited, It is preferable that it is 10-80 mass% in solid content 100 mass%, 20-80 mass% is more preferable, 30-80 It is more preferable that it is mass%, and it is further more preferable that it is 40-75 mass%.

[Conductive aid]
The solid electrolyte composition of the present invention may contain a conductive auxiliary agent used for improving the electronic conductivity of the active material, if necessary. As the conductive auxiliary agent, a general conductive auxiliary agent can be used. For example, graphites such as natural graphite or artificial graphite, carbon blacks such as acetylene black, ketjen black or furnace black, amorphous carbon such as needle coke, vapor grown carbon fiber or carbon nanotubes, which are electron conductive materials Carbon fiber such as graphene, carbonaceous material such as graphene or fullerene, metal powder such as copper or nickel, or metal fiber may be used. Conductivity such as polyaniline, polypyrrole, polythiophene, polyacetylene, or polyphenylene derivative A polymer may be used. Moreover, 1 type of these may be used and 2 or more types may be used.
When the solid electrolyte composition of the present invention contains a conductive auxiliary agent, the content of the conductive auxiliary agent in the solid electrolyte composition is not particularly limited and can be appropriately set in consideration of battery characteristics and the like. When the content is 100% by mass, 0.1 to 10% by mass is preferable.

[Dispersant]
The solid electrolyte composition of the present invention may contain a dispersant. By adding a dispersant, even when the concentration of either the electrode active material or the inorganic solid electrolyte is high, the aggregation can be suppressed, and a uniform active material layer and solid electrolyte layer can be formed.
The dispersant is not particularly limited, and examples thereof include a particle dispersant described later.
In the solid electrolyte composition of the present invention, when a dispersant is included, the content of the dispersant in the layer solid electrolyte composition is not particularly limited and can be appropriately set in consideration of battery characteristics and the like. In the case of 100 mass% per minute, 0.1-10 mass% is preferable.

(Particle dispersant)
The particle dispersant is preferably composed of a low molecular weight or oligomer having a molecular weight of 200 or more and less than 3000, at least one selected from the following functional group group (I), an alkyl group having 8 or more carbon atoms, or 10 or more carbon atoms. Are preferably contained in the same molecule.
Functional group (I): acidic group, group having basic nitrogen atom, (meth) acryl group, (meth) acrylamide group, alkoxysilyl group, epoxy group, oxetanyl group, isocyanate group, cyano group, thiol group and hydroxy Base

  The molecular weight of the particle dispersant is more preferably 300 or more and less than 2000, and particularly preferably 500 or more and less than 1000. When it is less than the above upper limit value, the aggregation of particles is less likely to occur, and the reduction in output can be effectively suppressed. Moreover, when it is more than the said lower limit, it will become difficult to volatilize in the step which apply | coats the slurry of a solid electrolyte composition, and dries.

  Among the functional group (I), an acidic group (for example, carboxy group, sulfonic acid group, phosphoric acid group), a group having a basic nitrogen atom (for example, amino group) or a cyano group is preferable, and an acidic group is more preferable. . Among the acidic groups, a carboxy group is particularly preferable.

  The particle dispersant preferably has an alkyl group having 8 or more carbon atoms or an aryl group having 10 or more carbon atoms.

  The alkyl group having 8 or more carbon atoms may be an alkyl group having 8 or more carbon atoms in total, and may be linear, branched, cyclic, or hydrocarbon, and is not limited to a carbon-carbon bond. A hetero atom may be contained in between. In addition, the alkyl group having 8 or more carbon atoms may be unsubstituted, may further have a substituent, and when it has a substituent, the substituent is preferably a halogen atom. Furthermore, you may have an unsaturated carbon-carbon bond in the middle.

  As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned, A fluorine atom is preferable.

The alkyl group having 8 or more carbon atoms is preferably an alkyl group having 8 to 50 carbon atoms, more preferably an alkyl group having 8 to 30 carbon atoms, still more preferably an alkyl group having 8 to 20 carbon atoms, 8 to 18 alkyl groups are particularly preferred.
Specifically, normal octyl, normal decyl, normal dodecyl, normal tetradecyl, normal hexadecyl, stearyl, lauryl, linole, linolene, 2-ethylhexyl, 2-ethyloctyl, 2-ethyldodecyl, polyethylene glycol monomethyl, perfluoro Examples include octyl or perfluorododecyl. Among them, normal octyl, 2-ethylhexyl, normal nonyl, normal decyl, normal undecyl, normal dodecyl, normal tetradecyl or normal octadecyl (stearyl) is preferable.

  The aryl group having 10 or more carbon atoms may be an aryl group having 10 or more total carbon atoms, and is not limited to being a hydrocarbon, and may contain a heteroatom between carbon-carbon bonds. In addition, the aryl group having 10 or more carbon atoms may be unsubstituted, may further have a substituent, and when it has a substituent, the substituent is preferably a halogen atom.

  The aryl group having 10 or more carbon atoms is preferably an aryl group having 10 to 50 carbon atoms, more preferably an aryl group having 10 to 30 carbon atoms, still more preferably an aryl group having 10 to 20 carbon atoms, An aryl group of 10 to 18 is particularly preferred. Specific examples include naphthyl, anthracenyl, pyrenyl, terphenyl, naphthacenyl, pentacenyl, benzopyrenyl, chrycenyl, triphenylenyl, corannulenyl, coronenyl, and oberenyl.

  Among these, a condensed aromatic hydrocarbon group is preferable.

  A particularly preferred combination is a combination having a carboxy group and an alkyl group having 8 or more carbon atoms in the same molecule. Specifically, a long-chain saturated fatty acid or a long-chain unsaturated fatty acid can be used more suitably.

  It is more preferable to have two or more groups represented by the functional group (I) in the same molecule and two or more alkyl groups having 8 or more carbon atoms or aryl groups having 10 or more carbon atoms.

[Method for producing solid electrolyte composition]
The solid electrolyte composition of the present invention can be produced by mixing an inorganic solid electrolyte, a polymer binder, and optionally other components, for example, using various mixers.

[Synthesis Method of Branched Polymer]
The branched polymer can be produced, for example, by polymerizing the monomer in the presence of an equimolar or more polymerization initiator with respect to the monomer having two or more polymerizable groups. The monomer used in this production method may be any monomer that has two or more polymerizable groups and can serve as the main chain and linking group of the branched polymer described above.
The polymerizable group that the monomer has is not particularly limited as long as it is a radical polymerizable group, and examples thereof include a polymerizable group having an ethylenic double bond. Examples of the polymerizable group having an ethylenic double bond include a vinyl group (including an allyl group) and a (meth) acryloyl group. Of these, a vinyl group, a (meth) acryloyl group and the like are preferable.

  The number of polymerizable groups possessed by the monomer may be two or more, preferably 2 to 12, and more preferably 2 to 6.

Monomers containing two or more vinyl groups include vinyl hydrocarbons, vinyl esters (including allyl esters), vinyl ethers (including allyl ethers), nitrogen-containing vinyl compounds, silicon-containing vinyl compounds, fluorine-containing vinyl compounds, and the like. And various monomers.
As a monomer containing two or more (meth) acryloyl groups, various monomers composed of (meth) acrylic acid ester, (meth) acrylic acid amide, alkylene glycol di (meth) acrylate, polyalkylene glycol di (meth) acrylate, and the like. Monomer. Among these, alkylene glycol di (meth) acrylate or polyalkylene glycol di (meth) acrylate is more preferable.

  Although it does not specifically limit as a vinyl type hydrocarbon, For example, an aliphatic vinyl type hydrocarbon, an alicyclic vinyl type hydrocarbon, or an aromatic vinyl type hydrocarbon is mentioned. Examples of the aliphatic vinyl hydrocarbon include isoprene, butadiene, 3-methyl-1,2-butadiene, 2,3-dimethyl-1,3-butadiene, 1,2-polybutadiene, pentadiene, hexadiene, and octadiene. Can be mentioned. Examples of the alicyclic vinyl hydrocarbon include cyclopentadiene, cyclohexadiene, cyclooctadiene, norbornadiene, and the like. Examples of the aromatic vinyl hydrocarbon include divinylbenzene, divinyltoluene, divinylxylene, trivinylbenzene, divinylbiphenyl, divinylnaphthalene, divinylfluorene, divinylcarbazole, and divinylpyridine.

  Although it does not specifically limit as vinyl ester, For example, vinyl ester compounds, such as divinyl adipate, divinyl maleate, divinyl phthalate, divinyl isophthalate, divinyl itaconate or vinyl (meth) acrylate, diallyl maleate, diallyl phthalate Alternatively, diallyl isophthalate, or allyl ester compounds such as diallyl adipate or allyl (meth) acrylate may be mentioned.

  Although it does not specifically limit as vinyl ether, For example, vinyl ether compounds, such as divinyl ether, diethylene glycol divinyl ether, or triethylene glycol divinyl ether, or diallyl ether, diallyloxyethane, triallyloxyethane, tetraallyloxyethane, tetraallyloxy Examples thereof include allyl ether compounds such as propane, tetraallyloxybutane, and tetramethallyloxyethane.

The nitrogen-containing vinyl compound is not particularly limited, and examples thereof include diallylamine, diallyl isocyanurate, diallyl cyanurate, methylene bis (meth) acrylamide, and bismaleimide.
Although it does not specifically limit as a silicon-containing vinyl type compound, For example, dimethyldivinylsilane, divinylmethylphenylsilane, diphenyldivinylsilane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, 1,3 -Divinyl-1,1,3,3-tetraphenyldisilazane or diethoxydivinylsilane.
Although it does not specifically limit as a fluorine-containing vinyl type compound, For example, 1, 4- divinyl perfluorobutane, 1, 4- divinyl octafluoro butane, 1, 6- divinyl perfluoro hexane, 1, 6- divinyl dodecafluoro hexane 1,8-divinylperfluorooctane or 1,8-divinylhexadecafluorooctane.

  Although it does not specifically limit as (meth) acrylic acid ester, For example, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, Trimethylolpropane tri (meth) acrylate, glycerol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, alkoxy titanium tri (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 2-methyl-1, 8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate Dioxane glycol di (meth) acrylate, 2-hydroxy-1-acryloyloxy-3-methacryloyloxypropane, 2-hydroxy-1,3-di (meth) acryloyloxypropane, 9,9-bis [4- ( 2- (meth) acryloyloxyethoxy) phenyl] fluorene, undecylenoxyethylene glycol di (meth) acrylate, bis [4- (meth) acryloylthiophenyl] sulfide, bis [2- (meth) acryloylthioethyl] sulfide 1,3-adamantanediol di (meth) acrylate, 1,3-adamantane dimethanol di (meth) acrylate, or the like.

  The alkylene glycol di (meth) acrylate is preferably an alkylene glycol (1 to 6 carbon atoms) di (meth) acrylate, more preferably an alkylene glycol (1 to 3 carbon atoms) di (meth) acrylate, and 2 carbon atoms. More preferred is ethylene glycol di (meth) acrylate.

  In the polyalkylene glycol di (meth) acrylate, the alkylene glycol preferably has 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, and still more preferably ethylene glycol. Moreover, the polymerization degree n of alkylene glycol should just be 2 or more, Preferably it is 2-40, More preferably, it is 3-20. Examples of such polyalkylene glycol di (meth) acrylate include polypropylene glycol di (meth) acrylate (propylene glycol polymerization degree 2-40) or polyethylene glycol di (meth) acrylate (ethylene glycol polymerization degree 2-40). ) And the like. Among these, ethylene glycol dimethacrylate or polyethylene glycol diacrylate (degree of polymerization of ethylene glycol n = 3 to 20 is preferable) is preferable.

The polymerization initiator is particularly limited as long as it is capable of polymerizing the above monomer and incorporating a radical portion generated by cleavage of the polymerization initiator during polymerization into the branched polymer as the above polymerization initiator residue. Chain transfer agents are also included.
Examples of such a polymerization initiator include a thermal radical polymerization initiator (also referred to as a thermal decomposition radical generation initiator), a photo radical polymerization initiator, and the like. Among these, a thermal radical polymerization initiator is preferable. In the present invention, these radical polymerization initiators and chain transfer agents can be used in combination.
The thermal radical polymerization initiator is not particularly limited as long as it is cleaved by heat to generate a radical. Examples of such polymerization initiators include azo polymerization initiators and peroxide polymerization initiators. Among these, an azo polymerization initiator is preferable.

  Examples of the azo polymerization initiator include an azonitrile polymerization initiator, an azo ester polymerization initiator, an azoamide polymerization initiator, an azoamidine polymerization initiator, and other azo polymerization initiators. Among these, an azonitrile polymerization initiator, an azoester polymerization initiator, or an azoamide polymerization initiator is preferable, and an azoester polymerization initiator is more preferable.

The azonitrile polymerization initiator is not particularly limited. For example, 2,2′-azobis (2-methylpropionitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2, 2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane) 1,1′-azobis (1-cyclohexanecarbonitrile) or 2- (carbamoylazo) isobutyronitrile.
The azo ester polymerization initiator is not particularly limited, and examples thereof include dimethyl-2,2-azobis (2-methylpropionate).

The azoamide polymerization initiator is not particularly limited, and examples thereof include 2,2′-azobis (N-butyl-2-methripropionamide), 2,2′-azobis (N-cyclohexyl-2-methylpropionamide), 2,2′-azobis (N-2-propenyl-2-methylpropionamide) 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide }, 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide ], 2,2'-azobis (N-butyl-2-methylpropionamide), 2,2'-azobis (N-cyclohexyl-2-methylpropionamide), etc. It is.
The azoamidine polymerization initiator is not particularly limited, and examples thereof include 2,2′-azobis (2-2-imidazolin-2-ylpropane) and 2,2′-azobis (2-2-imidazolin-2-ylpropane). ) Dihydrochloride, 2,2′-azobis (1-imino-1-pyrrolidino-2-methyl-propane) dihydrochloride, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2 '-Azobis (2-methylpropionamidine) dihydrochloride, 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] tetrahydrate, 2,2'-azobis [2- (2 -Imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] Sulfate dihydrate, 2,2′-azobis [2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane] dihydrochloride, 2,2′-azobis [2- (2- Imidazolin-2-yl) propane], 2,2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, and the like.

  Other azo polymerization initiators are not particularly limited as long as they are other than those described above. For example, 2,2′-azobis (2,4,4-trimethylpentane), dimethyl 2,2′-azobisisobutyrate, 4 , 4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2,4,4-trimethylpentane), 1,1′-azobis (1-acetoxy-1-phenylethane), or macropolymer An azo initiator is mentioned.

Among the azo polymerization initiators, an azo polymerization initiator having a 10-hour half-life temperature of 30 to 120 ° C. is preferable, an azo polymerization initiator having a 10-hour half-life temperature of 30 to 70 ° C. is particularly preferable, and 10 hours. An azo polymerization initiator having a half-life temperature of 40 to 70 ° C. is preferred.
Among the azo polymerization initiators, dimethyl 2,2′-azobisisobutyrate or 2,2′-azobis (2-methylbutyronitrile) is particularly preferable as the azo polymerization initiator that meets such conditions.

The peroxide polymerization initiator is not particularly limited, and examples thereof include ketone peroxide, diacyl peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, alkyl perester, and carbonate. Among these, diacyl peroxide, percarbonate, or ketone peroxide is preferable.
Other thermal radical polymerization initiators are not particularly limited, and ordinary ones can be used.

The chain transfer agent is not particularly limited, and examples thereof include mercaptan compounds such as alkyl mercaptan compounds or aryl mercaptan compounds, dithioesters or trithiocarbonate compounds. The alkyl group in the above compound preferably has 1 to 12 carbon atoms, and the aryl group preferably has 6 to 24 carbon atoms. Among these, a mercaptan compound having an ester group, an amide group, a carbonate group or an alkylene oxide group as a substituent is preferable.
Other polymerization initiators are not particularly limited, and ordinary ones can be used.

  In the method for producing a branched polymer, the monomer is polymerized in the presence of an equimolar or more polymerization initiator with respect to the monomer. Thus, by polymerizing a monomer in the presence of an excess of a polymerization initiator or the like, three or more radicals generated by cleavage of the polymerization initiator can be incorporated at the end of the polymer. The amount of the polymerization initiator used may be 1 mol or more with respect to the total number of moles of monomers to be polymerized, and is preferably 1.2 mol or more, more preferably from the viewpoint of allowing the interaction with the solid particles to be dense. Is 1.5 mol or more, more preferably 2 mol or more. On the other hand, the use amount of the polymerization initiator or the like is preferably 100 mol or less, more preferably 50 mol or less, and further preferably 30 mol or less, from the viewpoint of durability such as the tensile strength of the polymer.

  In the method for producing a branched polymer, a monomer having one polymerizable group can be used in addition to the above monomer. Such a monomer is not particularly limited, and examples thereof include (meth) acrylic acid ester, (meth) acrylic acid, acrylic acid amide, (meth) acrylonitrile, styrene, alkylene (including diene), and the like. .

  As a polymerization method for the monomer, a normal polymerization method can be employed without any particular limitation. For example, solution polymerization, dispersion polymerization, precipitation polymerization, bulk polymerization and the like can be mentioned, and solution polymerization is preferable. The solution polymerization method is not particularly limited, but a method of polymerizing the monomer by dropping the solution of the monomer and the polymerization initiator into a solution maintained at a polymerization temperature described later is preferable.

  The solvent used for solution polymerization is not particularly limited. For example, hydrocarbon solvents (toluene, heptane, xylene), ester solvents (ethyl acetate, propylene glycol monomethyl ether acetate), ether solvents (tetrahydrofuran, dioxane, 1,2-diethoxyethane), ketone solvents (acetone, methyl ethyl ketone, cyclohexanone) ), A nitrile solvent (acetonitrile, propionitrile, butyronitrile, isobutyronitrile) or a halogen solvent (dichloromethane, chloroform).

  The polymerization reaction can be performed under normal pressure (1 atm), under pressure or under reduced pressure, and is preferably performed under normal pressure. Moreover, although superposition | polymerization atmosphere is not specifically limited, It is preferable to carry out in inert gas atmosphere, such as nitrogen gas or argon gas.

The temperature of the polymerization reaction (polymerization temperature) is not particularly determined as long as it is equal to or higher than the temperature at which the polymerization initiator is cleaved to generate radicals. For example, 40-200 degreeC is preferable and 50-180 degreeC is more preferable.
The time for the polymerization reaction is not uniquely determined by the type of monomer, the polymerization temperature, and the like. For example, 1 to 20 hours is preferable, and 3 to 10 hours is more preferable.

According to the above production method, a branched polymer having three or more polymerization initiator residues at the end of the polymer molecule can be produced.
In this production method, the number of polymerization initiator residues can be set to a predetermined number depending on the amount of monomer added during production, the equivalent amount of the polymerization initiator, the reaction temperature, and the like.
Further, the molecular weight of the branched polymer can be appropriately determined by GPC measurement according to the measurement method and conditions in the examples described later.
Furthermore, the above molar ratio [Bs] / [Bn] can be appropriately determined according to the ratio of side chain components and initiator components by ¹ H-NMR and / or ¹³ C-NMR.

[All-solid-state secondary battery sheet]
The all-solid-state secondary battery sheet of the present invention may be a sheet used for an all-solid-state secondary battery, and includes various modes depending on the application. For example, a sheet preferably used for a solid electrolyte layer (also referred to as a solid electrolyte sheet for an all-solid secondary battery), a sheet preferably used for an electrode or a laminate of an electrode and a solid electrolyte layer (an electrode sheet for an all-solid secondary battery) Etc. In the present invention, these various sheets may be collectively referred to as an all-solid secondary battery sheet.

  The sheet for an all solid state secondary battery of the present invention is a sheet having a solid electrolyte layer on a substrate. The all-solid-state secondary battery sheet may have other layers as long as it has a base material and a solid electrolyte layer, but those having an active material layer are all-solid-state secondary battery electrodes to be described later. Sort into sheets. Examples of other layers include a protective layer, a conductive auxiliary layer, and a binder layer.

  In the all-solid-state secondary battery sheet of the present invention, the substrate is not particularly limited as long as it can support a solid electrolyte layer or the like, and is a sheet of the material, organic material, inorganic material, or the like described in the current collector. A body (plate-shaped body) etc. are mentioned. Examples of the organic material include various polymers, cellulose, a porous resin sheet, and the like. Specifically, polymers such as polyethylene, polypropylene, polyester, or Teflon (registered trademark), or cellulose having a substituent (cellulose acetylpropylene). And pionate). As an inorganic material, metal foils, such as glass, aluminum, copper, or SUS, etc. are mentioned, for example.

The configuration and layer thickness of the solid electrolyte layer of the all-solid secondary battery sheet are the same as the configuration and layer thickness of the solid electrolyte layer described in the all-solid secondary battery of the present invention.
This sheet is obtained by forming (coating and drying) the solid electrolyte composition of the present invention on a base material (which may be via another layer) to form a solid electrolyte layer on the base material. It is done.
Here, the solid electrolyte composition of the present invention can be prepared by the above-described method.

  The solid electrolyte sheet for an all-solid secondary battery (also simply referred to as “solid electrolyte sheet”) as a preferred embodiment of the sheet for the all-solid secondary battery of the present invention is a solid electrolyte layer of the all-solid secondary battery of the present invention. In which a solid electrolyte layer and preferably a protective layer are provided in this order on the substrate.

An electrode sheet for an all-solid-state secondary battery (also simply referred to as “electrode sheet”) as a preferred embodiment of the sheet for an all-solid-state secondary battery of the present invention has an active material layer on a metal foil as a current collector. It is an electrode sheet. This electrode sheet is usually a sheet having a current collector and an active material layer, but an embodiment having a current collector, an active material layer, and a solid electrolyte layer in this order, and a current collector, an active material layer, and a solid electrolyte The aspect which has a layer and an active material layer in this order is also included.
The configuration and layer thickness of each layer constituting the electrode sheet are the same as the configuration and layer thickness of each layer described in the all-solid-state secondary battery of the present invention.
The electrode sheet is obtained by forming (coating and drying) the solid electrolyte composition containing the active material of the present invention on a metal foil to form an active material layer on the metal foil. The method for preparing the solid electrolyte composition containing the active material is the same as the method for preparing the solid electrolyte composition except that the active material is used.

[Manufacture of all-solid-state secondary batteries]
The all-solid secondary battery can be produced by a conventional method. Specifically, an all-solid secondary battery can be produced by forming each of the above layers using the solid electrolyte composition of the present invention. This will be described in detail below.

The all-solid-state secondary battery of the present invention is produced by a method including (intervening) the step of applying the solid electrolyte composition of the present invention onto a metal foil to be a current collector and forming (forming) a coating film. it can.
For example, a solid electrolyte composition containing a positive electrode active material is applied as a positive electrode material (positive electrode layer composition) on a metal foil that is a positive electrode current collector to form a positive electrode active material layer. A positive electrode sheet for a secondary battery is prepared. Next, a solid electrolyte composition for forming a solid electrolyte layer is applied on the positive electrode active material layer to form a solid electrolyte layer. Furthermore, a solid electrolyte composition containing a negative electrode active material is applied as a negative electrode material (negative electrode layer composition) on the solid electrolyte layer to form a negative electrode active material layer. An all-solid-state secondary battery having a structure in which a solid electrolyte layer is sandwiched between a positive electrode active material layer and a negative electrode active material layer is obtained by stacking a negative electrode current collector (metal foil) on the negative electrode active material layer. Can do. If necessary, this can be enclosed in a housing to obtain a desired all-solid secondary battery.
Moreover, the formation method of each layer is reversed, and a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer are formed on the negative electrode current collector, and the positive electrode current collector is stacked to produce an all-solid secondary battery. You can also

Another method includes the following method. That is, a positive electrode sheet for an all-solid secondary battery is produced as described above. In addition, a solid electrolyte composition containing a negative electrode active material is applied as a negative electrode material (a composition for a negative electrode layer) on a metal foil that is a negative electrode current collector to form a negative electrode active material layer. A negative electrode sheet for a secondary battery is prepared. Next, a solid electrolyte layer is formed on one of the active material layers of these sheets as described above. Furthermore, the other of the positive electrode sheet for an all solid secondary battery and the negative electrode sheet for an all solid secondary battery is laminated on the solid electrolyte layer so that the solid electrolyte layer and the active material layer are in contact with each other. In this way, an all-solid secondary battery can be manufactured.
Another method includes the following method. That is, as described above, a positive electrode sheet for an all-solid secondary battery and a negative electrode sheet for an all-solid secondary battery are produced. Separately from this, a solid electrolyte composition is applied onto a substrate to produce a solid electrolyte sheet for an all-solid secondary battery comprising a solid electrolyte layer. Furthermore, it laminates | stacks so that the solid electrolyte layer peeled off from the base material may be pinched | interposed with the positive electrode sheet for all solid secondary batteries, and the negative electrode sheet for all solid secondary batteries. In this way, an all-solid secondary battery can be manufactured.

The method for applying the solid electrolyte composition is not particularly limited, and can be appropriately selected. Examples thereof include coating (preferably wet coating), spray coating, spin coating coating, dip coating, slit coating, stripe coating, and bar coating coating.
At this time, the solid electrolyte composition may be dried after being applied, or may be dried after being applied in multiple layers. The drying temperature is not particularly limited. The lower limit is preferably 30 ° C or higher, more preferably 60 ° C or higher, and still more preferably 80 ° C or higher. The upper limit is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, and further preferably 200 ° C. or lower. By heating in such a temperature range, a dispersion medium can be removed and it can be set as a solid state. Further, it is preferable because the temperature is not excessively raised and each member of the all-solid-state secondary battery is not damaged. Thereby, in the all-solid-state secondary battery, excellent overall performance can be obtained, and good binding properties and good ionic conductivity can be obtained even without pressure.

It is preferable to pressurize each layer or all solid state secondary battery after producing the applied solid electrolyte composition or all solid state secondary battery. An example of the pressurizing method is a hydraulic cylinder press. The applied pressure is not particularly limited and is generally preferably in the range of 10 to 1500 MPa.
Moreover, you may heat the apply | coated solid electrolyte composition simultaneously with pressurization. It does not specifically limit as heating temperature, Generally, it is the range of 30-300 degreeC. It is also possible to press at a temperature higher than the glass transition temperature of the inorganic solid electrolyte. In addition, it can also press at the temperature higher than the glass transition temperature of the said polymer contained in a polymer binder. However, in general, the temperature does not exceed the melting point of the polymer.
The pressurization may be performed in a state where the coating solvent or the dispersion medium is dried in advance, or may be performed in a state where the solvent or the dispersion medium remains.

The atmosphere during pressurization is not particularly limited, and may be any of the following: in the air, in dry air (dew point -20 ° C. or lower), or in an inert gas (for example, in argon gas, helium gas, or nitrogen gas). Good.
The pressing time may be a high pressure in a short time (for example, within several hours), or a medium pressure may be applied for a long time (1 day or more). In the case of an all-solid-state secondary battery other than the all-solid-state secondary battery sheet, for example, a restraining tool (screw tightening pressure or the like) of the all-solid-state secondary battery can be used in order to keep applying moderate pressure.
The pressing pressure may be uniform or different with respect to the pressed part such as the sheet surface.
The pressing pressure can be changed according to the area and film thickness of the pressed part. Also, the same part can be changed stepwise with different pressures.
The press surface may be smooth or roughened.

(Initialization)
The all solid state secondary battery manufactured as described above is preferably initialized after manufacture or before use. The initialization is not particularly limited, and can be performed, for example, by performing initial charging / discharging in a state in which the press pressure is increased, and then releasing the pressure until the general use pressure of the all-solid secondary battery is reached.

[Use of all-solid-state secondary batteries]
The all solid state secondary battery of the present invention can be applied to various uses. Although there is no particular limitation on the application mode, for example, when installed in an electronic device, a notebook computer, a pen input personal computer, a mobile personal computer, an electronic book player, a mobile phone, a cordless phone, a pager, a handy terminal, a mobile fax machine, a mobile phone Copy, portable printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, mini-disc, electric shaver, transceiver, electronic notebook, calculator, memory card, portable tape recorder, radio, backup power supply, memory card, etc. Is mentioned. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, or medical equipment (such as pacemakers, hearing aids, shoulder massagers). Furthermore, it can be used for various military purposes and space. Moreover, it can also combine with a solar cell.

  In particular, it is preferably applied to applications that require high capacity and high rate discharge characteristics. For example, in power storage facilities and the like that are expected to increase in capacity in the future, high safety is essential, and further compatibility of battery performance is required. In addition, electric vehicles and the like are equipped with a high-capacity secondary battery and are expected to be charged every day at home, and further safety is required against overcharging. According to the present invention, it is possible to exhibit the excellent effect correspondingly to such a usage pattern.

An all-solid secondary battery refers to a secondary battery in which the positive electrode, the negative electrode, and the electrolyte are all solid. In other words, it is distinguished from an electrolyte type secondary battery using a carbonate-based solvent as an electrolyte. In this, this invention presupposes an inorganic all-solid-state secondary battery. The all-solid secondary battery includes an organic (polymer) all-solid secondary battery using a polymer compound such as polyethylene oxide as an electrolyte, and an inorganic all-solid using the above-described Li-PS, LLT, and / or LLZ. It is divided into secondary batteries. The application of the polymer compound to the inorganic all-solid secondary battery is not hindered, and the polymer compound can be applied as the positive electrode active material, the negative electrode active material and / or the polymer binder particles of the inorganic solid electrolyte particles. .
The inorganic solid electrolyte is distinguished from the above-described electrolyte (polymer electrolyte) using a polymer compound such as polyethylene oxide as an ion conductive medium, and the inorganic compound serves as an ion conductive medium. Specific examples include Li-PS, LLT, or LLZ. The inorganic solid electrolyte itself does not release cations (Li ions) but exhibits an ion transport function. On the other hand, a material that is added to the electrolytic solution or the solid electrolyte layer and serves as a source of ions that release cations (Li ions) is sometimes called an electrolyte, but it is distinguished from the electrolyte as the ion transport material. In this case, this is called “electrolyte salt” or “supporting electrolyte”. Examples of the electrolyte salt include LiTFSI (lithium bistrifluoromethanesulfonimide).
In the present invention, the term “composition” means a mixture in which two or more components are uniformly mixed. However, as long as the uniformity is substantially maintained, aggregation and uneven distribution may partially occur within a range in which a desired effect is achieved. In particular, when it is referred to as a solid electrolyte composition, it basically refers to a composition (typically a paste) that is a material for forming a solid electrolyte layer or the like, and an electrolyte layer or the like formed by curing the composition. Shall not be included in this.

  Below, based on an Example, it demonstrates still in detail about this invention. The present invention is not construed as being limited thereby. In the following examples, “part” and “%” representing the composition are based on mass unless otherwise specified. “Room temperature” means 25 ° C.

[Example 1]
In Example 1, a solid electrolyte composition was prepared and the binding property of the solid electrolyte layer was evaluated.
(Synthesis of branched polymer)
Branched polymers A-1 to A-13 and comparative branched polymer EA-1 were synthesized as follows.
The linking group and polymerization initiator residue of each branched polymer synthesized are shown in Tables 1-1 and 1-2 (also referred to collectively as Table 1 below). For each branched polymer, the mass average molecular weight was measured by GPC under the following conditions, and the number of polymerization initiator residues per molecule (average value) determined from the measurement results of ¹ H-NMR (the following conditions). Table 1 shows the number of moles of the polymerization initiator residue [Bs] / number of moles of the linking group component [Bn].

(I) Synthesis of branched polymer A-1 10.2 g (51 mmol) of ethylene glycol dimethacrylate (manufactured by Wako Pure Chemical Industries) and dimethyl-2,2′-azobis (2-methylpropionate) as a thermal radical polymerization initiator ) (Trade name: V-601, manufactured by Wako Pure Chemical Industries) Was prepared. 21 mL of cyclohexanone was put into a 300 mL flask replaced with a nitrogen atmosphere, and the temperature was raised to 108 ° C. while stirring, and then the prepared monomer solution was added dropwise at a rate of 0.6 mL / min. After completion of dropping, the obtained liquid was further heated and stirred at 108 ° C. for 3 hours. This liquid was returned to room temperature and then added to 500 mL of petroleum ether. The precipitate was collected to obtain a branched polymer A-1.
In the branched polymer A-1 thus synthesized, the repeating unit (main chain) was an alkylene chain (—CH ₂ —CH (CH ₃ ) —).

(Ii) Synthesis of branched polymer A-2 In the synthesis of branched polymer A-1, in place of ethylene glycol dimethacrylate, polyethylene glycol diacrylate (light acrylate 14EG-A (trade name), polymerization degree n of ethylene glycol n A branched polymer A-2 was synthesized in the same manner as the synthesis of the branched polymer A-1, except that 38.2 g (51 mmol) (≈14, manufactured by Kyoeisha Chemical Co., Ltd.) was used. The main chain of the obtained branched polymer A-2 was an alkylene chain (—CH ₂ —CH ₂ —).

(Iii) Synthesis of branched polymer A-3 In the synthesis of branched polymer A-1, instead of ethylene glycol dimethacrylate, polyethylene glycol diacrylate (light acrylate 9EG-A (trade name), ethylene glycol polymerization degree n ≒ 9, manufactured by Kyoeisha Chemical Co., Ltd.) 26.7 g (51 mmol), azobisisobutyronitrile (AIBN) 14.3 g (87 mmol) was used instead of V-601 as the thermal radical polymerization initiator, and the reaction temperature was A branched polymer A-3 was synthesized in the same manner as the synthesis of the branched polymer A-1, except that the temperature was changed to 100 ° C. The main chain of the obtained branched polymer A-3 was an alkylene chain (—CH ₂ —CH ₂ —).

(Iv) Synthesis of branched polymer A-4 In the synthesis of branched polymer A-1, instead of ethylene glycol dimethacrylate, polyethylene glycol diacrylate (light acrylate 3EG-A (trade name), polymerization degree of ethylene glycol n A branched polymer A-4 was synthesized in the same manner as the synthesis of the branched polymer A-1, except that ˜3, manufactured by Kyoeisha Chemical Co., Ltd.) and ethylene glycol dimethacrylate (molar ratio 1: 1) were used. The main chain of the obtained branched polymer A-4 was an alkylene chain (—CH ₂ —CH (CH ₃ ) — and —CH ₂ —CH ₂ —).

(V) Synthesis of branched polymer A-5 In the synthesis of branched polymer A-1, branched polymer A-1 was used except that 6.7 g (51 mmol) of divinylbenzene was used instead of ethylene glycol dimethacrylate. The branched polymer A-5 was synthesized in the same manner as in the above. The main chain of the obtained branched polymer A-5 was an alkylene chain (—CH ₂ —CH ₂ —).

(Vi) Synthesis of branched polymer A-6 In the synthesis of branched polymer A-1, 12 g (51 mmol) of glycerin dimethacrylate was used instead of ethylene glycol dimethacrylate, and instead of V-601 as a thermal radical polymerization initiator. Except that 2,2′-azobis (N-butyl-2-methylpropionamide) (VAm-110 (trade name), Wako Pure Chemicals, 1.7 times mol with respect to glycerin dimethacrylate) was used. A branched polymer A-6 was synthesized in the same manner as the synthesis of the branched polymer A-1. The main chain of the obtained branched polymer A-6 was an alkylene chain (—CH ₂ —CH (CH ₃ ) —).

(Vii) Synthesis of branched polymer A-7 In the synthesis of branched polymer A-3, instead of polyethylene glycol diacrylate, 11.5 g of trimethylolpropane trimethacrylate (34 mmol, molar amount of AIBN relative to trimethylolpropane trimethacrylate) The branched polymer A-7 was synthesized in the same manner as the synthesis of the branched polymer A-3 except that 2.55 mol) was used. The main chain of the obtained branched polymer A-7 was an alkylene chain (—CH ₂ —CH (CH ₃ ) —).

(Viii) Synthesis of branched polymer A-8 In the synthesis of branched polymer A-2, the amount of polyethylene glycol diacrylate used was 65 g (87 mmol, the molar amount of the thermal radical polymerization initiator relative to polyethylene glycol diacrylate was 1 time mol) The branched polymer A-8 was synthesized in the same manner as the synthesis of the branched polymer A-2 except that the reaction temperature was changed to 90 ° C.
(Ix) Synthesis of branched polymer A-9 In the synthesis of branched polymer A-2, the amount of polyethylene glycol diacrylate used was 70 g (94 mmol, the molar amount of the thermal radical polymerization initiator relative to polyethylene glycol diacrylate was 1.08. The branched polymer A-9 was synthesized in the same manner as the synthesis of the branched polymer A-2 except that the reaction temperature was set to 95 ° C.
(X) Synthesis of branched polymer A-10 In the synthesis of branched polymer A-2, the amount of polyethylene glycol diacrylate used was 15 g (21 mmol, the molar amount of the thermal radical polymerization initiator relative to polyethylene glycol diacrylate was 4.14. A branched polymer A-10 was synthesized in the same manner as the synthesis of the branched polymer A-2 except that it was changed to 2 mol).

(Xi) Synthesis of branched polymer A-11 In the synthesis of branched polymer A-5, as a thermal radical polymerization initiator (peroxide polymerization initiator), benzoyl peroxide (Niper BMT-K-40 (trade name), Branched polymer A was prepared in the same manner as the synthesis of branched polymer A-5 except that 52 g (86 mmol, 1.69 times mol with respect to divinylbenzene) of 40% xylene diluted solution, manufactured by NOF Corporation was used. -11 was synthesized.

(Xii) Synthesis of branched polymer A-12 In the synthesis of branched polymer A-1, 20.0 g (87 mmol) of dimethyl-2,2′-azobis (2-methylpropionate) was used as a thermal radical polymerization initiator. In addition to using 7.8 g (87 mmol) of 1-butanethiol which is a chain transfer agent (total molar amount of polymerization initiator with respect to ethylene glycol dimethacrylate is 3.41 times mol), branched polymer A In the same manner as in the synthesis of -1, a branched polymer A-12 was synthesized.

(Xiii) Synthesis of branched polymer A-13 In the synthesis of branched polymer A-2, the amount of thermal radical polymerization initiator used was changed to 65 g (87 mmol, 1 mol per polyethylene glycol diacrylate) and reacted. A branched polymer A-13 was synthesized in the same manner as the synthesis of the branched polymer A-2 except that the temperature was changed to 70 ° C.

(Xiv) Comparative branched polymer EA-1
In the synthesis of the branched polymer A-1, 1.0 g (0.4 mmol, ethylene glycol dimethacrylate) was used as the thermal radical polymerization initiator, dimethyl-2,2′-azobis (2-methylpropionate). The branched polymer EA-1 was synthesized in the same manner except that the reaction temperature was changed to 0.0078 times mol) and the reaction temperature was changed to 70 degrees. EA-1 was a system that partially gelled in the reaction vessel and had insolubles.

<Measurement of mass average molecular weight>
The weight average molecular weight of the branched polymer was converted to standard polystyrene by GPC according to the measuring device and measurement conditions.
Column: TOSOH TSKgel Super HZM-H,
TOSOH TSKgel Super HZ4000,
TOSOH TSKgel Super HZ2000 (both trade names, manufactured by Tosoh Corporation)
A column connected with was used.
Carrier: Tetrahydrofuran Measurement temperature: 40 ° C
Carrier flow rate: 1.0 ml / min
Sample concentration: 0.1% by mass
Detector: RI (refractive index) detector

^<1 H-NMR measurement conditions>
0.1 mg of branched polymer and 5 ml of deuterated chloroform containing 0.1% tetramethylsilane were put in an NMR tube, respectively, and the branched polymer was dissolved to prepare a sample solution. The NMR tube was measured with a nuclear magnetic resonance spectrometer (NMR, 300 MHz, manufactured by BRUKER).

[Sulfide-based inorganic solid electrolyte: Synthesis of Li-PS-based glass]
As a sulfide-based inorganic solid electrolyte, T.I. Ohtomo, A .; Hayashi, M .; Tatsumisago, Y. et al. Tsuchida, S .; Hama, K .; Kawamoto, Journal of Power Sources, 233, (2013), pp231-235, and A.A. Hayashi, S .; Hama, H .; Morimoto, M .; Tatsumisago, T .; Minami, Chem. Lett. , (2001), pp 872-873, a Li-PS glass was synthesized.
Specifically, in a glove box under an argon atmosphere (dew point −70 ° C.), 2.42 g of lithium sulfide (Li ₂ S, manufactured by Aldrich, purity> 99.98%) and diphosphorus pentasulfide (P ₂ S ₅ , 3.90 g manufactured by Aldrich, purity> 99%) was weighed, put into an agate mortar, and mixed for 5 minutes using an agate pestle. The mixing ratio of Li ₂ S and P ₂ S ₅ was set to Li ₂ S: P ₂ S ₅ = 75: 25 in terms of molar ratio.
66 g of zirconia beads having a diameter of 5 mm were introduced into a 45 mL container (manufactured by Fritsch) made of zirconia, the whole mixture of lithium sulfide and diphosphorus pentasulfide was introduced, and the container was completely sealed under an argon atmosphere. A container is set in a planetary ball mill P-7 (trade name, manufactured by Fritsch) manufactured by Fricht Co., and mechanical milling is performed at a temperature of 25 ° C. and a rotation speed of 510 rpm for 20 hours, whereby a sulfide-based inorganic solid electrolyte of yellow powder (Li-PS-based glass) 6.20 g was obtained.

(Preparation of polymer binder)
(I) Polymer binder B-1, 7, 9, 11 and 13 not containing lithium salt, and polymer binder EB-1 for comparison
As shown in Table 2 below, as the polymer binder not containing a lithium salt, the branched polymer synthesized above was used as it was.
(Ii) Polymer binder B-2 to 6, 8, 10, 12, 14 to 19 containing lithium salt
As shown in Table 2 below, 0.9 g of branched polymer and 0.1 g of lithium salt were charged into a 50 mL eggplant flask and dissolved in 5 g of acetonitrile. After confirming complete dissolution, each polymer binder was prepared by distilling off acetonitrile under reduced pressure.

(Preparation of solid electrolyte composition)
(I) Preparation of Solid Electrolyte Compositions SO-1 to 180 180 zirconia beads having a diameter of 5 mm were put into a 45 mL container (made by Fritsch) made of zirconia, and an oxide-based inorganic solid electrolyte LLT (made by Toshima Seisakusho). 0 g and 1.0 g of a polymer binder shown in Table 3 (the total mass of the LLT and the polymer binder is 100 parts by mass) were added, and 20 g of methyl ethyl ketone was added as a dispersion medium. Thereafter, this container is set on a planetary ball mill P-7 manufactured by Fritsch, and mixing is continued for 2 hours at a temperature of 25 ° C. and a rotation speed of 300 rpm, and zirconia beads are removed to prepare solid electrolyte compositions SO-1 to SO-3, respectively. did.

(Ii) Preparation of solid electrolyte composition SS-1 180 zirconia beads having a diameter of 5 mm were placed in a 45 mL container (manufactured by Fritsch) made of zirconia, and the sulfide-based inorganic solid electrolyte Li-PS system synthesized above. 9.0 g of glass, 1.0 g of a polymer binder shown in Table 3 (the total mass of the Li—PS system glass and the polymer binder is 100 parts by mass), and 15.0 g of toluene as a dispersion medium were added. Thereafter, this container was set on a planetary ball mill P-7, and stirring was continued for 2 hours at a temperature of 25 ° C. and a rotation speed of 300 rpm to remove zirconia beads, thereby preparing a solid electrolyte composition SS-1.
(Iii) Preparation of solid electrolyte composition SS-2 to 21 In preparation of solid electrolyte composition SS-1, as shown in Table 3 below, the amount of Li-PS-based glass used and the type of polymer binder The solid electrolyte compositions SS-2 to 21 were prepared in the same manner as the preparation of the solid electrolyte composition SS-1, except that at least one of the amount used and the type of the dispersion medium was changed.

(Iv) Preparation of solid electrolyte compositions TS-1 to TS-3 for comparison In the preparation of the solid electrolyte composition SS-1, as shown in Table 3 below, the amount of Li-PS-based glass used In the case of TS-2 and TS-3, the type of polymer binder and the amount used, and further the type of the dispersion medium were changed in the same manner as in the preparation of the solid electrolyte composition SS-1, except that each was changed to a solid. Electrolyte compositions TS-1 to TS-3 were respectively prepared.
The polymer binders T-1 and T-2 used are as follows.
T-1: PVDF-HFP (manufactured by Arkema: KYNAR FLEX 2500-20)
T-2: Hydrogenated SBR

(V) Preparation of Solid Electrolyte Composition TO-1 for Comparison In the preparation of the solid electrolyte composition SO-1, the polymer binder was changed to the polymer binder T-1 as shown in Table 3 below. Except for this, the solid electrolyte composition TO-1 was prepared in the same manner as in the preparation of the solid electrolyte composition SO-1.

  For each prepared solid electrolyte composition, the mass ratio [A + E] / [B] of the total content [A + E] of the inorganic solid electrolyte and electrode active material to the content [B] of the polymer binder is shown in Table 3 below. Show.

[Evaluation of binding properties]
(I) Production of sheet for all-solid-state secondary battery (solid electrolyte sheet for all-solid-state secondary battery) Each of the solid electrolyte compositions prepared above was applied to an applicator (trade name: SA) -201 Baker type applicator (manufactured by Tester Sangyo Co., Ltd.), heated at 80 ° C. for 1 hour, and further heated at 120 ° C. for 1 hour to dry the solid electrolyte composition. Then, using the heat press machine, the dried solid electrolyte composition was pressurized, heating at 150 degreeC (600 Mpa, 10 second), and the solid electrolyte sheet for all-solid-state secondary batteries was obtained, respectively. The film thickness of the solid electrolyte layer was 70 μm.

(Ii) About each produced solid electrolyte sheet for all-solid-state secondary batteries, the peeling test was done and binding property was evaluated. The result was shown in Table 4.
Each solid electrolyte sheet for all-solid-state secondary batteries was punched five times with a punching machine (manufactured by Nogami Giken Co., Ltd.) with a diameter of 10 mm, and the solid electrolyte layer The peeled state was evaluated. As the evaluation results, the most frequently used criteria among the following criteria were adopted in five punching tests.
For the surface of the solid electrolyte layer,
A: Area of the solid electrolyte layer peeled off is 1/10 or less B: Area of the peeled solid electrolyte layer is more than 1/10 and less than 1/2 C: Area of the peeled solid electrolyte layer is 1/2 or more

  As shown in Table 4, the solid electrolyte composition of the present invention was found to exhibit high binding properties when used as a material for the solid electrolyte layer and / or active material layer of an all-solid secondary battery. . Moreover, peeling (peeling) of the solid electrolyte layer from the aluminum foil can be suppressed. Also from this point, the solid electrolyte layer formed of the solid electrolyte composition of the present invention has no gap between the electrode interfaces. It can be seen that the ionic conductivity is high.

[Example 2]
In Example 2, an all-solid-state secondary battery (see FIG. 2) having the layer configuration shown in FIG. 1 was produced and its performance was evaluated.
[Preparation of composition for positive electrode layer]
In a planetary mixer (TK Hibismix (trade name), manufactured by Primix), 5 parts by mass of acetylene black, 100 parts by mass of the positive electrode active material described in Table 5 below, and 80 parts by mass (solid content) of the solid electrolyte composition And stirring was performed for 1 hour at a rotation speed of 150 rpm and a temperature of 25 ° C. to prepare respective compositions for the positive electrode layer.
For each of the prepared positive electrode layer compositions, the mass ratio [A + E] / [B] of the total content [A + E] of the inorganic solid electrolyte and the electrode active material with respect to the content [B] of the polymer binder is shown in Table 5 below. It shows.

[Preparation of composition for negative electrode layer]
In a planetary mixer (TK Hibismix (trade name), manufactured by Primix), 5 parts by mass of acetylene black, 30 parts by mass of the negative electrode active material described in Table 6 below, and 80 parts by mass (solid content) of the solid electrolyte composition Was added, and the mixture was stirred at a rotation speed of 150 rpm and a temperature of 25 ° C. for 1 hour, thereby preparing a negative electrode layer composition.
For each prepared positive electrode layer composition, the mass ratio [A + E] / [B] of the total content [A + E] of the inorganic solid electrolyte and electrode active material to the content [B] of the polymer binder is shown in Table 6 below. It shows.
In this negative electrode layer composition, acetylene black was used as a conductive additive.

[Production of all-solid-state secondary batteries]
The coin battery (all-solid secondary battery) shown in FIG. 2 was produced as follows.
As shown in Table 7, each positive electrode layer composition prepared above was applied onto an aluminum foil (current collector) having a thickness of 20 μm with an applicator (trade name: SA-201 Baker type applicator), and 80 ° C. And then heated at 110 ° C. for 1 hour to dry the positive electrode layer composition. Then, using a heat press, the positive electrode layer composition was pressurized while being heated to 120 ° C. (600 MPa, 1 minute), and had a thickness of 150 μm (positive electrode active material layer) having a positive electrode active material layer / aluminum foil laminated structure. A positive electrode sheet for an all-solid-state secondary battery having a thickness of 130 μm).
Next, on the positive electrode active material layer of the positive electrode sheet for an all-solid-state secondary battery, the solid electrolyte composition described in Table 7 below was applied by an applicator (trade name: SA-201 Baker type applicator) to obtain a solid electrolyte composition. The product was heated at 80 ° C. for 1 hour, and further heated at 100 ° C. for 1 hour to form a solid electrolyte layer having a thickness of 50 μm. In this way, a positive electrode sheet for an all-solid secondary battery having a laminated structure of aluminum foil / positive electrode active material layer / solid electrolyte layer was produced.

  Then, on the solid electrolyte layer of the positive electrode sheet for an all-solid-state secondary battery, the composition for a negative electrode layer shown in Table 7 was further applied by an applicator (trade name: SA-201 Baker type applicator). The composition was heated at 80 ° C. for 1 hour, and further heated at 110 ° C. for 1 hour to form a negative electrode active material layer having a thickness of 100 μm. Further, a laminate in which a copper foil having a thickness of 20 μm is stacked on the negative electrode active material layer is pressurized while being heated to 120 ° C. using a heat press machine (600 MPa, 1 minute), and the sheet having the layer configuration shown in FIG. A laminate was produced.

  The sheet laminate thus obtained was cut into a disk shape having a diameter of 14.5 mm. The cut sheet laminate 12 was placed in a stainless steel 2032 type coin case 11 incorporating a spacer and a washer (both not shown in FIG. 2). In this way, a coin battery 13 having the layer configuration shown in FIG. 1 was produced.

<Evaluation of cycle characteristics>
The cycle characteristics of the all-solid-state secondary battery were evaluated by the discharge capacity and the number of charge / discharge cycles measured by a charge / discharge evaluation apparatus manufactured by Toyo System Co., Ltd .: TOSCAT-3000 (trade name).
Charging is performed until the battery voltage reaches 4.2 V at a current density of 0.1 mA / cm ^2. After reaching 4.2 V, constant voltage charging is performed until the current density becomes less than 0.01 mA / cm ^2. did. Discharging was performed at a current density of 0.1 mA / cm ² until the battery voltage reached 3V. This charging / discharging was repeated 4 cycles, and the initialization process was performed.
The battery after initialization was charged at a constant current until the battery voltage reached 4.2 V at a current density of 0.2 mA / cm ² . Next, constant current discharge was performed until the battery voltage reached 3 V at a current density of 0.4 mA / cm ² (first cycle). This constant current charge and constant current discharge were repeated, and the number of cycles (times) when the discharge capacity was less than 80 when the discharge capacity in the first cycle was set to 100 was counted.

<Evaluation of rate of change in discharge due to high temperature storage (also called high temperature cycle characteristics)>
Using the battery that had been initialized in the same manner as the evaluation of the cycle characteristics, the rate of change in discharge after the storage test was measured.
Specifically, after the initialization, performed a constant current charge at a current density of 0.2 mA / cm ² at 30 ° C. in a constant temperature bath until the battery voltage reached 4.2 V, current density of 0.4 mA / cm ² in 3 The battery was discharged until it reached 0V. The discharge capacity at this time is referred to as Q _1.
Next, constant current charging was performed again until the battery voltage reached 4.2 V at a current density of 0.2 mA / cm ² , and after completion, the temperature of the thermostatic chamber was raised to 50 ° C. and held for 3 days. Then, after discharging until the battery voltage reaches 3.0 V at a current density of 0.1 mA / cm ² , a constant current charge is performed until the battery voltage reaches 4.2 V at a current density of 0.2 mA / cm ² , and then The battery was discharged at a current density of 0.4 mA / cm ² until reaching 3.0V. The discharge capacity at this time is referred to as Q _2.
Using electric capacity Q ₁ and Q ₂ obtained above, based on the following equation, to evaluate the discharge rate of change due to high-temperature storage (%) of.
Rate of change in discharge due to high temperature storage (%) = (Q ₂ / Q ₁ ) × 100

  From the results of Table 7, the solid electrolyte composition of the present invention containing a polymer binder containing a branched polymer having three or more polymerization initiator residues generated by cleavage of the polymerization initiator used during polymerization and an inorganic solid electrolyte The all-solid-state secondary battery using the product has high cycle characteristics and high temperature cycle characteristics. This excellent effect was also shown in the all-solid-state secondary battery even when any of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer was formed with the solid electrolyte composition of the present invention. . Thus, according to the present invention, it was possible to obtain an all-solid-state secondary battery having excellent cycle characteristics and also excellent high-temperature cycle characteristics (high-temperature stability).

  On the other hand, using each composition for comparison containing a polymer binder containing polymer EA-1 or the like that does not have three or more initiator residues at the polymer terminal and an inorganic solid electrolyte, The all-solid-state secondary battery in which all layers of the active material layer, the negative electrode active material layer, and the solid electrolyte layer are formed has insufficient cycle characteristics and high-temperature cycle characteristics.

  According to the results of Examples 1 and 2, the solid electrolyte composition of the present invention retains high ionic conductivity when used as a material for the solid electrolyte layer and / or active material layer of an all-solid-state secondary battery. It was shown that there was an excellent effect that even high binding properties could be realized. Further, the all-solid-state secondary battery sheet, the all-solid-state secondary electrode sheet, and the all-solid-state secondary battery of the present invention utilize the solid electrolyte composition that exhibits the above-described excellent effects, and have excellent cycle characteristics. Demonstrated battery performance such as high temperature stability.

DESCRIPTION OF SYMBOLS 1 Negative electrode collector 2 Negative electrode active material layer 3 Solid electrolyte layer 4 Positive electrode active material layer 5 Positive electrode collector 6 Actuation site 10 All-solid secondary battery 11 Coin case 12 All-solid-state secondary battery sheet 13 Coin battery

Claims (15)

A solid electrolyte composition comprising an inorganic solid electrolyte having conductivity of ions of metal elements belonging to Group 1 or Group 2 of the periodic table, and a polymer binder,
The polymeric binder, more than two at the end of the polymer molecules having a crosslinked structure, have a polar substituent group derived from a polymerization initiator of the polymer molecules, and the crosslinked structure having a linking group containing an alkylene oxide group containing branched crosslinked polymer solid electrolyte composition. The branched crosslinked polymer is a polymer in which the number of moles of a linking group [Bn] and the number of moles of the polar substituent [Bs] satisfy a relationship of [Bs] / [Bn] ≧ 0.1. 2. The solid electrolyte composition according to 1. Wherein the polar substituent is a solid electrolyte composition according to claim 1 or 2 which is a polar substituent derived from at least one polymerization initiator of the heat radical polymerization initiator and a chain transfer agent. The polar substituent has at least one group selected from the group consisting of a cyano group, an ester group, a heterocyclic group, an amidine group, an acyl group, an amide group, an alkoxy group, and a sulfide group. The solid electrolyte composition according to any one of the above. The solid electrolyte composition according to any one of claims 1 to 4, wherein the polar substituent is represented by any of the following formulas (S1) to (S7).

In formulas (S1) to (S7), L represents a divalent linking group. X represents an oxygen atom or a sulfur atom. R ^s11 , R ^s21 , R ^s41 , R ^s42 , R ^s61 and R ^s71 each independently represent a substituent. n ^{s11 to} n ^s51 are each independently an integer of 0 to 10. Q ^s5 represents a heterocyclic ring containing -C = N-. * Represents a linking site with the end of the polymer molecule. The solid electrolyte composition according to claim 5, wherein the formulas (S1) to (S5) are respectively the following formulas (S1B) to (S5B).

In formulas (S1B) to (S5B), X represents an oxygen atom or a sulfur atom. R ^s11, represents a ^{R s13, R s14, R s21} , R s23, R s24, R s33, R s34, R s41, R s42, R s43, R s44, R s53 and ^{R s54} each independently represent a substituted group. Q ^s5 represents a heterocyclic ring containing -C = N-. * Represents a linking site with the end of the polymer molecule. The linking group is an oxygen atom, a nitrogen atom, a sulfur atom, a solid electrolyte according to at least one of any one of the heteroatoms including claims 1-6 selected from the group consisting of a phosphorus atom and a silicon atom Composition.   The solid electrolyte composition according to claim 1, wherein the linking group includes the alkylene oxide group as a repeating unit.   The solid according to any one of claims 1 to 8, wherein the polymer binder contains at least one of a metal salt containing a metal element ion belonging to Group 1 or Group 2 of the periodic table and a molten salt. Electrolyte composition.   The solid electrolyte composition according to any one of claims 1 to 9, wherein a mass average molecular weight of the branched crosslinked polymer is 1000 to 300,000 in terms of polystyrene by gel permeation chromatography.   The solid electrolyte composition according to any one of claims 1 to 10, comprising an active material capable of inserting and releasing ions of metal elements belonging to Group 1 or Group 2 of the Periodic Table.   The mass ratio [A + E] / [B] of the total content [A + E] of the inorganic solid electrolyte and the electrode active material with respect to the content [B] of the polymer binder is in the range of 1,000 to 1. 11. The solid electrolyte composition according to any one of 11 above.   The solid electrolyte sheet for all-solid-state secondary batteries which formed the solid electrolyte composition of any one of Claims 1-10 and 12 on the base material.   The electrode sheet for all-solid-state secondary batteries which formed the solid electrolyte composition of Claim 11 into a film on metal foil.   An all solid state secondary battery comprising a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer,
  The all-solid-state secondary battery whose at least 1 layer of the said positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer is a layer formed with the solid electrolyte composition of any one of Claims 1-12.

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