JPWO2022138886A5 - - Google Patents

Description

The present invention relates to an all-solid-state battery with excellent load characteristics and an electrode that can constitute the all-solid-state battery.

In recent years, with the development of portable electronic devices such as mobile phones and notebook personal computers, and the practical use of electric vehicles, there has been a need for small, lightweight batteries with high capacity and high energy density. ing.

Currently, lithium batteries that can meet this demand, particularly lithium ion batteries, use an organic electrolyte containing an organic solvent and a lithium salt as a non-aqueous electrolyte.

With the further development of equipment to which lithium-ion batteries can be applied, there is a need for lithium-ion batteries to have a longer lifespan, higher capacity, and higher energy density. Lithium-ion batteries with increased energy density are also required to be highly reliable.

However, since the organic electrolyte used in lithium-ion batteries contains an organic solvent, which is a flammable substance, there is a possibility that the organic electrolyte will generate abnormal heat if an abnormal situation such as a short circuit occurs in the battery. There is. In addition, with the recent trend towards higher energy densities in lithium ion batteries and an increase in the amount of organic solvents in organic electrolytes, there is a demand for even greater reliability in lithium ion batteries.

Under the above circumstances, all-solid-state lithium batteries (all-solid-state batteries) that do not use organic solvents are attracting attention. All-solid-state batteries use molded solid electrolytes that do not use organic solvents instead of conventional organic solvent-based electrolytes, and are highly safe because there is no risk of abnormal heat generation of the solid electrolytes.

In addition, all-solid-state batteries are not only highly safe, but also highly reliable, highly environmentally resistant, and have a long lifespan, so they can continue to contribute to the development of society while also contributing to safety and security. It is expected to be a maintenance-free battery. By providing all-solid-state batteries to society, we aim to achieve Goal 12 (Ensure sustainable production and consumption patterns) and Goal 3 (Ensure sustainable production and consumption patterns) of the 17 Sustainable Development Goals (SDGs) established by the United Nations. Goal 7 (Ensure healthy lives and promote well-being for all), Goal 7 (Ensure access to affordable, reliable, sustainable and modern energy for all) and Goal 11 (Inclusive can contribute to the achievement of safe, resilient and sustainable cities and human settlements.

Furthermore, various improvements have been attempted in all-solid-state batteries. For example, Patent Document 1 describes that the performance of an all-solid-state battery can be improved by using a material made of a granulated mixture of a sulfide-based inorganic solid electrolyte and an electrode active material.

In addition, in Patent Document 1, a powder of a sulfide-based inorganic solid electrolyte and a powder of an electrode active material are mixed to form a mixed powder, and this is pressure-molded to once form a compact, and then all the above-mentioned Manufactures materials for solid-state batteries. Through this manufacturing method, in the all-solid-state battery material, a plurality of electrode active material particles are adjacent to each other to form an electron conduction path, and furthermore, sulfide-based An inorganic solid electrolyte is placed, and the particles of the sulfide-based inorganic solid electrolyte are deformed and bonded to each other by pressure molding, and the particle shape disappears and becomes a continuous phase, forming an ion conduction path. It is said that

JP 2014-192061 A (Claims, paragraphs [0015] and [0016])

By the way, the field of application of all-solid-state batteries is currently expanding rapidly, and for example, applications that require discharging at large current values are considered, so load characteristics must be adjusted to meet this demand. It is necessary to improve this.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an all-solid-state battery with excellent load characteristics and an electrode that can constitute the all-solid-state battery.

The electrode for an all-solid-state battery of the present invention includes a molded body of an electrode mixture, the electrode mixture includes an electrode material composite, and the electrode material composite includes a granulated material containing an active material and a solid electrolyte. The solid electrolyte is characterized in that it includes a granular argyrodite-type sulfide-based solid electrolyte.

Further, the all-solid-state battery of the present invention includes a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode, wherein at least one of the positive electrode and the negative electrode is the all-solid-state battery of the present invention. It is characterized by being an electrode for batteries.

Note that the all-solid-state battery of the present invention includes a primary battery (all-solid-state primary battery) and a secondary battery (all-solid-state secondary battery).

According to the present invention, it is possible to provide an all-solid-state battery with excellent load characteristics and an electrode that can constitute the all-solid-state battery.

FIG. 1 is a plan view schematically showing a part of a molded body of an electrode mixture included in an electrode for an all-solid-state battery of the present invention. FIG. 2 is an enlarged view of the area surrounded by the dotted line in FIG. FIG. 3 is a plan view schematically showing another example of a molded body of an electrode mixture included in an electrode for an all-solid-state battery of the present invention. FIG. 4 is a plan view schematically showing another example of a molded body of an electrode mixture included in an electrode for an all-solid-state battery of the present invention. FIG. 5 is a cross-sectional view schematically showing an example of the all-solid-state battery of the present invention. FIG. 6 is a plan view schematically showing another example of the all-solid-state battery of the present invention. FIG. 7 is a sectional view taken along line II in FIG. 6.

<Electrodes for all-solid-state batteries>
The electrode for an all-solid-state battery of the present invention is used as a positive electrode or a negative electrode of an all-solid-state battery, and has a molded body of an electrode mixture containing an electrode material composite. The electrode material composite is composed of granules containing an active material and a solid electrolyte, and contains a granular argyrodite-type sulfide solid electrolyte as the solid electrolyte.

For example, when a molded body of an electrode mixture constituting an electrode for an all-solid-state battery is produced by simply mixing an active material and a solid electrolyte to form a mixed powder, and then press-molding this, it is generally not active. The surface unevenness of the material particles is relatively large, and the solid electrolyte particles cannot follow the uneven shape well, resulting in a relatively large gap between the active material particles and the solid electrolyte particles. There are certain limits to the improvement of ionic conductivity (lithium ion conductivity) in These points have been a factor hindering improvement in the load characteristics of all-solid-state batteries.

Therefore, in the electrode for an all-solid-state battery of the present invention, an electrode material composite formed by pre-granulating an active material and an argyrodite-type sulfide-based solid electrolyte is contained in a molded electrode mixture. In this case, since the active material and the argyrodite-type sulfide-based solid electrolyte constitute a granule, the contact between the active material particles in the electrode material composite and the argyrodite-type sulfide-based solid electrolyte particles This is better than a simple mixture of active material particles and solid electrolyte particles. Therefore, even when a solid electrolyte different from the solid electrolyte used in the electrode material composite is mixed with the electrode material composite to form a molded body of the electrode mixture, the solid electrolyte in the electrode material composite Due to the action of the electrolyte, the ionic conductivity within the molded body of the electrode mixture is improved, so in an all-solid-state battery (all-solid-state battery of the present invention) using the all-solid-state battery electrode of the present invention having this molded body, This makes it possible to ensure excellent load characteristics.

The argyrodite-type sulfide-based solid electrolyte contained in the electrode material composite included in the all-solid-state battery electrode of the present invention is granular.

In the all-solid battery material described in Patent Document 1, as described above, the sulfide-based inorganic solid electrolyte interposed between the particles of the electrode active material becomes a continuous phase that has lost its particle shape. Patent Document 1 states that a good ion conduction path is formed by the continuous phase of the sulfide-based inorganic solid electrolyte, so if this description is followed, the ion conductivity inside the electrode will be increased to create an all-solid-state battery. In order to improve the load characteristics of the active materials, it is expected that it is preferable that the solid electrolyte present between the active materials forms a continuous phase rather than a granular (particle shape).

However, according to the studies of the present inventors, contrary to these expectations, in an electrode material composite consisting of a granule containing an active material and an argyrodite-type sulfide solid electrolyte contained in an electrode for an all-solid-state battery, It has been found that the presence of the solid electrolyte in granular form is advantageous in improving the load characteristics of an all-solid-state battery. The reason for this is not certain, but I suspect it to be as follows.

Argyrodite-type sulfide-based solid electrolytes are usually provided in granular form (particles), but these granular argyrodite-type sulfide-based solid electrolytes are crystallized and are more stable than amorphous states. It also has high ionic conductivity. In an electrode for an all-solid-state battery, when the sulfide-based solid electrolyte that exists between the active materials becomes a continuous phase in which particles bind together and lose their original shape (granularity), it becomes amorphous. It is considered that the crystallinity of the solid electrolyte is very low, and that the solid electrolyte is no longer able to fully exhibit its inherent ionic conductivity.

On the other hand, if the argyrodite-type sulfide-based solid electrolyte in the electrode material composite contained in the electrode for all-solid-state batteries can exist while maintaining its original granularity, its crystallinity can also be compared. Therefore, the electrode material composite, which is a granule, has high ionic conductivity. It is assumed that by using this, it is possible to form an all-solid-state battery with excellent load characteristics.

In the electrode for an all-solid-state battery of the present invention, the fact that the molded electrode mixture contains an electrode material composite consisting of granules containing an active material and an argyrodite-type sulfide-based solid electrolyte is significant. In the image of the cross section of the molded body of the agent observed at 10,000 times using a scanning electron microscope (SEM), 10 or more primary particles of the active material are aggregated, and there are no gaps between the primary particles of the active material. There are places where the gap is 5 μm or less, and furthermore, in the image observed at 30,000x magnification, it is observed that granular solid electrolyte (argyrodite-type sulfide-based solid electrolyte, and electrode material composite) is contained between the primary particles of the active material. Confirm by the presence of other solid electrolytes). The gap between the primary particles of the active material is preferably 4 μm or less, more preferably 3 μm or less, and is usually 0.5 μm or more, although it depends on the particle size of the solid electrolyte.

It should be noted that during the above observation, the solid electrolyte (argyrodite-type sulfide-based solid electrolyte and other solid electrolytes that may be contained in the electrode material composite) existing between the primary particles of the active material is granular. If the solid electrolyte has a contour of , the solid electrolyte is considered to be granular. For example, if two solid electrolyte particles are in close contact with each other and the interface between each particle is ambiguous, if the shape of the particles is assumed to be a circle in plan view, more than 60% of the circumference will be If it can be confirmed, it is considered to have a granular outline.

FIG. 1 and FIG. 2 are drawings schematically showing an example of a part of a molded body of an electrode mixture included in an electrode for an all-solid-state battery of the present invention. FIG. 1 is a plan view showing a part of a molded body of an electrode mixture, and FIG. 2 is an enlarged view of the area surrounded by a dotted line in FIG.

The area surrounded by an ellipse in FIG. 1 is an electrode material composite 1 consisting of granules of an active material and an argyrodite-type sulfide solid electrolyte (hereinafter also simply referred to as argyrodite-type solid electrolyte). The composite 1 includes a solid electrolyte 2 added separately from the argyrodite solid electrolyte constituting the electrode material composite 1, and an active material (active material) added separately from the active material constituting the electrode material composite 1. Together with the primary particles) 3, they form a molded body of the electrode mixture. In the electrode material composite 1, ten or more primary particles 1a of the active material are aggregated. However, the ellipse shown in FIG. 1 includes a part of the solid electrolyte 2 that exists around the electrode material composite 1 and does not constitute the electrode material composite 1. A part of the primary particles 1a of the active material protrudes from the ellipse shown in FIG. 1 (the same applies to FIGS. 3 and 4, which will be described later). Further, in FIG. 1, the argyrodite solid electrolyte that constitutes the electrode material composite 1 is not shown (the same applies to FIGS. 3 and 4, which will be described later).

As shown in FIG. 2, granular argyrodite-type sulfide-based solid electrolyte 1b exists in the gaps between the primary particles 1a of the active material in the electrode material composite 1.

FIG. 3 and FIG. 4 are drawings schematically showing other examples of a molded body of the electrode mixture included in the electrode for an all-solid-state battery of the present invention. The molded electrode mixture shown in FIG. 3 is formed of an electrode material composite 1 and a solid electrolyte 2 (different from the argyrodite solid electrolyte that constitutes the electrode material composite 1). That is, all of the active materials contained in the molded electrode mixture shown in FIG. 3 constitute the electrode material composite 1. On the other hand, the molded electrode mixture shown in FIG. It is formed of an active material (primary particles of active material) 3 different from that which constitutes the body 1 .

As electrodes for all-solid-state batteries, there are molded bodies (such as pellets) formed by molding an electrode mixture, and structures in which a layer (mixture layer) of a molded electrode mixture is formed on a current collector. Examples include things.

When the electrode for an all-solid-state battery is a positive electrode and is used in an all-solid-state primary battery, the active material of the electrode material composite contained in the molded electrode mixture may include a conventionally known non-aqueous electrolyte. The same positive electrode active material used in primary batteries can be used. Specifically, for example, manganese dioxide; lithium-containing manganese oxide [for example, LiMn ₃ O ₆ , or a crystal structure that has the same crystal structure as manganese dioxide (β type, γ type, or a structure in which β type and γ type are mixed, etc.) and a Li content of 3.5% by mass or less, preferably 2% by mass or less, more preferably 1.5% by mass or less, particularly preferably 1% by mass or less], Li _a Ti Lithium-containing composite oxides such as _5/3 O ₄ (4/3≦a<7/3); vanadium oxides; niobium oxides; titanium oxides; sulfides such as iron disulfide; graphite fluoride; Ag ₂ Silver sulfides such as S; nickel oxides such as NiO ₂ ; and the like.

In addition, when the electrode for an all-solid-state battery is a positive electrode and is used for an all-solid-state secondary battery, the active material of the electrode material composite to be contained in the molded electrode mixture may include conventionally known active materials. The same positive electrode active material used in non-aqueous electrolyte secondary batteries, that is, an active material capable of inserting and releasing Li (lithium) ions, can be used. Specifically, Li _1-x M _r Mn _2-r O ₄ (where M is Li, Na, K, B, Mg, Ca, Sr, Ba, Ti, V, Cr, Zr, Fe, Co , Ni, Cu, Zn, Al, Sn, Sb, In, Nb, Ta, Mo, W, Y, Ru and Rh, and 0≦x≦1,0 ≦r≦1), a spinel-type lithium manganese composite oxide, Li _r Mn _(1-st) Ni _s M _t O _(2-u) F _v (where M is Co, Mg, Al, B , Ti, V, Cr, Fe, Cu, Zn, Zr, Mo, Sn, Ca, Sr and W, and 0≦r≦1.2, 0<s <0.5, 0≦t≦0.5, u+v<1, -0.1≦u≦0.2, 0≦v≦0.1), Li _1-x Co _{1- r} M _r O ₂ (M is Al, Mg, Ti, V, Cr, Zr, Fe, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, Ba, Mn, Bi, Ca , F, P, Sr, W, Si, Ta, K, S, Er and Na, and 0≦x≦1, 0≦r≦0.5). The represented lithium cobalt composite oxide, Li _1-x Ni _1-r M _r O ₂ (where M is Al, Mg, Ti, Zr, Fe, Co, Cu, Zn, Ga, Ge, Nb, Mo , Sn, Sb, and Ba, and is at least one element selected from the group consisting of 0≦x≦1, 0≦r≦0.5) Lithium-nickel composite oxide, Li _1+sx M _1-r N _r PO ₄ F _s (M is at least one element selected from the group consisting of Fe, Mn and Co, and N is Al, Mg, Ti, Zr, Ni, Cu, Zn , Ga, Ge, Nb, Mo, Sn, Sb, V and Ba, and 0≦x≦1, 0≦r≦0.5, 0≦s≦1 ), an olivine-type composite oxide represented by Li _2-x M _1-r N _r P ₂ O ₇ (where M is at least one element selected from the group consisting of Fe, Mn and Co, N is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, V and Ba, and 0≦x Examples include pyrophosphoric acid compounds represented by the following formulas: ≦2, 0≦r≦0.5), and only one type of these compounds may be used, or two or more types thereof may be used in combination.

In the case of a positive electrode for an all-solid-state battery used in an all-solid-state secondary battery, a lithium-cobalt composite oxide (A) represented by the following general formula (1) is preferably used among the above-mentioned positive electrode active materials.

LiCo _1-abc Al _a M ¹ _b M ² _c O ₂ (1)

In the general formula (1), M ¹ is at least one element selected from the group consisting of Mg, Ni and Na, M ² is Mn, Fe, Cu, Zr, Ti, Bi, Ca, F, At least one element selected from the group consisting of P, Sr, W, Ba, Nb, Si, Zn, Mo, V, Sn, Sb, Ta, Ge, Cr, K, S and Er, and 0<a<0.1,0<b<0.1,a+b<0.1, 0≦c.

When lithium cobalt composite oxide (A) is used as a positive electrode active material for a non-aqueous electrolyte secondary battery that uses an organic electrolyte, it causes damage to the inside of the battery due to the action of additive elements such as Al and ^M1 elements. A material that increases resistance. However, in the case of non-aqueous electrolyte secondary batteries that have an organic electrolyte, the electrolyte that transfers ions between the positive and negative electrodes is liquid (electrolyte), so the internal resistance is low, so lithium The increase in internal resistance due to the cobalt composite oxide (A) has little effect on battery characteristics. On the other hand, in all-solid-state secondary batteries in which ions are transferred between the positive electrode and the negative electrode using a solid electrolyte, an increase in internal resistance due to the action of the positive electrode active material may cause a decrease in battery characteristics such as load characteristics. is expected.

However, contrary to these expectations, when lithium cobalt composite oxide (A) is used as the positive electrode active material of an all-solid-state secondary battery, the internal resistance is lower than, for example, when LiCoO ₂ is used as the positive electrode active material. This makes it possible to further improve the load characteristics of the all-solid-state secondary battery.

When a battery using LiCoO ₂ as a positive electrode active material is charged, Co expands due to a change in valence. In batteries using organic electrolytes, even if the volume of the positive electrode active material changes due to this, the electrolyte that transfers ions is liquid, so the contact between the electrolyte and the positive electrode active material will not be impaired. do not have. On the other hand, in all-solid-state secondary batteries, the electrolyte that transfers ions in the positive electrode is solid (solid electrolyte), so the positive electrode active material and solid electrolyte change in volume as the battery is charged and discharged. A gap is created between the two, increasing the internal resistance of the positive electrode and, ultimately, the internal resistance of the battery.

However, in the case of the lithium cobalt composite oxide (A) represented by the general formula (1), even in a charged state, the expansion of Co is suppressed by the action of Al and element ^M1 , so that the positive electrode active material The overall amount of expansion (volume change) becomes smaller. Therefore, by using a positive electrode for an all-solid battery that uses lithium cobalt composite oxide (A) as the positive electrode active material, contact between the lithium cobalt composite oxide (A) and the solid electrolyte within the positive electrode can be prevented even during charging and discharging. Since the internal resistance can be maintained well and the internal resistance can be kept low, an all-solid-state secondary battery with better load characteristics can be obtained.

In the lithium cobalt composite oxide (A), Al is an element substituted into Co sites, and ^M1 is an element substituted with Li sites. It has the effect of reducing the amount of expansion].

The lithium cobalt composite oxide (A) only needs to contain at least one element selected from Mg, Ni, and Na as the element ^M1 , but the lithium cobalt composite oxide (A) may contain at least one element selected from Mg, Ni, and Na. Mg is preferred because it does not cause a change in valence during discharge.

In the lithium cobalt composite oxide (A), from the viewpoint of suppressing the amount of expansion during charging, the amount a of Al is greater than 0 and less than 0.1, and the amount b of the element ^M1 is greater than 0 and less than 0.1. and a+b is less than 0.1. Note that the amount a of Al is preferably 0.005 or more, and the amount b of element M ¹ is preferably 0.005 or more. Further, the amount a of Al is preferably 0.08 or less, and the amount b of element M ¹ is preferably 0.08 or less.

The lithium cobalt composite oxide (A) may or may not contain the element M ² (the amount c may be 0), but if the amount of the element M ² is too large, e.g. There is a possibility that the amount of Co will decrease and the capacity of the lithium cobalt composite oxide (A) will decrease. Therefore, the amount c of element M ² is preferably 0.05 or less.

When the electrode for an all-solid-state battery is a negative electrode and is used for an all-solid-state primary battery, the active material of the electrode material composite to be contained in the molded electrode mixture is metallic lithium, lithium alloy (lithium-aluminum alloy), etc. alloy, lithium-indium alloy, etc.).

In addition, when the electrode for an all-solid-state battery is a negative electrode and is used for an all-solid-state secondary battery, the active material of the electrode material composite to be contained in the molded electrode mixture is a conventionally known active material. There is no particular restriction as long as it is an active material that is used in lithium secondary batteries and is capable of intercalating and deintercalating lithium ions. For example, carbon that can absorb and release lithium such as graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, mesocarbon microbeads (MCMB), and carbon fibers can be used as negative electrode active materials. One or a mixture of two or more of these materials may be used. An oxide may be used as the negative electrode active material, for example, Li _x Nb _y TiM ⁶ _a O _[5y+4/2]+ δ (where M ⁶ is V, Cr, Mo, Ta, Zr, Mn , Fe, Mg, B, Al, Cu, and Si, and 0≦x≦49, 0.5≦y<24, -5≦δ≦5, 0≦a ≦0.3), titanium dioxide having an anatase structure, lithium titanate having a ramsdellite structure represented by Li ₂ Ti ₃ O ₇ , Li ₄ Examples include a spinel-type lithium titanium composite oxide represented by Ti ₅ O ₁₂ , and one or more of these can be used. Elements, compounds, and alloys thereof containing elements such as Si, Sn, Ge, Bi, Sb, and In; Nitride containing transition metals such as Co, Ni, Mn, Fe, Cr, Ti, and W, and lithium Alternatively, compounds such as oxides that can be charged and discharged at low voltages similar to those of lithium metal; or metallic lithium or lithium alloys (lithium-aluminum alloy, lithium-indium alloy, etc.) can also be used as the negative electrode active material.

The active material of the electrode material composite may have a reaction suppression layer on its surface for suppressing the reaction between the active material and the solid electrolyte. In particular, when the electrode for an all-solid-state battery is a positive electrode, it is preferable that a reaction suppression layer is provided on the surface of the active material (positive electrode active material).

The reaction suppression layer may be made of a material that has ionic conductivity and can suppress the reaction between the active material and the solid electrolyte. Examples of materials that can constitute the reaction suppression layer include, for example, oxides containing Li and at least one element selected from the group consisting of Nb, P, B, Si, Ge, Ti, and Zr; Examples include Nb-containing oxides such as LiNbO ₃ , Li ₃ PO ₄ , Li ₃ BO ₃ , Li ₄ SiO ₄ , Li ₄ GeO ₄ , LiTiO ₃ , LiZrO ₃ , Li ₂ WO ₄ and the like. The reaction suppression layer may contain only one type of these oxides, or may contain two or more types of these oxides, and may further contain multiple types of these oxides in a composite compound. may be formed. Among these oxides, it is preferable to use Nb-containing oxides, and it is more preferable to use LiNbO ₃ .

The reaction suppression layer is preferably present on the surface in an amount of 0.1 to 1.0 parts by weight based on 100 parts by weight of the active material (base material particles on which the reaction suppression layer is formed). Within this range, the reaction between the active material and the solid electrolyte can be suppressed well.

Examples of methods for forming a reaction suppression layer on the surface of the active material include a sol-gel method, a mechanofusion method, a CVD method, a PVD method, and an ALD method.

Argyrodite-type sulfide-based solid electrolytes are mainly used as the solid electrolyte of the electrode material composite to be contained in the molded body of the electrode mixture of the electrode for all-solid-state batteries. It can also be a solid electrolyte.

Examples of the argyrodite type sulfide solid electrolyte include those represented by the following general formula (2) represented by Li ₆ PS ₅ Cl and the following general formula (3).

Li _7-x+y PS _6-x Cl _x+y (2)

In the general formula (2), 0.05≦y≦0.9, −3.0x+1.8≦y≦−3.0x+5.7.

Li _7-p PS _6-p Cl _q Br _r (3)

In the general formula (3), p=q+r, 0<p≦1.8, and 0.1≦q/r≦10.0.

In addition to the argyrodite-type sulfide-based solid electrolyte, other solid electrolytes can also be used as the solid electrolyte of the electrode material composite in the electrode for an all-solid-state battery. Examples of such other solid electrolytes include sulfide-based solid electrolytes other than the argyrodite-type sulfide-based solid electrolytes, hydride-based solid electrolytes, halide-based solid electrolytes, oxide-based solid electrolytes, and the like.

Examples of sulfide solid electrolytes other than the argyrodite type sulfide solid electrolyte include Li ₂ S-P ₂ S ₅ , Li ₂ S-SiS ₂ , Li ₂ S-P ₂ S ₅ -GeS ₂ , Li ₂ S-B Examples include glass-based particles such as _2S3 ; LGPS _- based particles ( _{Li10GeP2S12 , etc.} ).

Examples of the hydride solid electrolyte include LiBH ₄ , a solid solution of LiBH ₄ and the following alkali metal compound (for example, one in which the molar ratio of LiBH ₄ to the alkali metal compound is 1:1 to 20:1), and the like. Can be mentioned. Examples of the alkali metal compounds in the solid solution include lithium halides (LiI, LiBr, LiF, LiCl, etc.), rubidium halides (RbI, RbBr, RbF, RbCl, etc.), and cesium halides (CsI, CsBr, CsF, CsCl, etc.). , lithium amide, rubidium amide, and cesium amide.

Examples of the halide solid electrolyte include monoclinic LiAlCl ₄ , defective spinel type or layered LiInBr ₄ , and monoclinic Li _6-3m Y _m X ₆ (where 0<m<2 and X=Cl or Br), and in addition, known ones described in International Publication No. 2020/070958 and International Publication No. 2020/070955 can be used.

Examples of oxide-based solid electrolytes include garnet-type Li ₇ La ₃ Zr ₂ O ₁₂ , NASICON-type Li _1+O Al _1+O Ti _2-O (PO ₄ ) ₃ , Li _1+p Al ₁₊ Examples include _p Ge _2-p (PO ₄ ) ₃ and perovskite-type Li _3q La _2/3-q TiO ₃ .

In addition, when using another solid electrolyte together with the argyrodite-type sulfide-based solid electrolyte in the electrode material composite, the proportion of the argyrodite-type sulfide-based solid electrolyte in the total amount of solid electrolyte in the electrode material composite is set to 70%. It is preferable to set it as mass % or more. Furthermore, since it is preferable that all of the solid electrolyte used in the electrode material composite be an argyrodite-type sulfide-based solid electrolyte, the proportion of the argyrodite-type sulfide-based solid electrolyte in the total amount of solid electrolyte in the electrode material composite is The preferred upper limit of is 100% by mass.

The shape of the argyrodite-type sulfide solid electrolyte contained in the electrode material composite contained in the electrode mixture molded body is not particularly limited as long as it is in the form of particles, for example, the primary particle size measured by the following method. As long as Rs satisfies the following values, it may have any shape such as spherical, ellipsoidal, or plate-like. Further, when the electrode material composite also contains a solid electrolyte other than the argyrodite-type sulfide-based solid electrolyte, it is preferable that the shape of the other solid electrolyte is also granular.

The average particle diameter of the primary particles of the active material contained in the electrode material composite is Ra, and the solid electrolyte contained in the electrode material composite (the electrode material composite also contains other solid electrolytes other than the argyrodite solid electrolyte) When the average particle diameter of the primary particles (including the other solid electrolytes) is Rs, the ratio Ra/Rs is preferably 2 or more, more preferably 4 or more, It is most preferably 6 or more, more preferably 50 or less, more preferably 35 or less, and most preferably 18 or less. For example, Ra/Rs can be set within the ranges of 2-50, 2-35, 2-18, 4-50, 4-35, 4-18, 6-50, 6-35, and 6-18. When Ra/Rs satisfies the above value, the contact between the active material and the solid electrolyte in the electrode material composite becomes better, and the effect of increasing the load characteristics of the all-solid-state battery becomes better. .

The average particle diameter Ra of the primary particles of the active material in the electrode material composite is preferably 1 μm or more, more preferably 3 μm or more, most preferably 4 μm or more, and preferably 25 μm or less. , more preferably 15 μm or less, most preferably 10 μm or less. For example, Ra can be set within the range of 1 to 25 μm, 1 to 15 μm, 1 to 10 μm, 3 to 25 μm, 3 to 15 μm, 3 to 10 μm, 4 to 25 μm, 4 to 15 μm, and 4 to 10 μm.

Further, the average particle diameter Rs of the primary particles of the solid electrolyte in the electrode material composite is preferably 0.2 μm or more, more preferably 0.4 μm or more, preferably 3 μm or less, and 1 μm or more. More preferably, it is .8 μm or less. For example, Rs can be set within the ranges of 0.2 to 3 μm, 0.2 to 1.8 μm, 0.4 to 3 μm, and 0.4 to 1.8 μm.

The average particle diameter of the primary particles of the active material contained in the electrode material composite is a value determined as follows. Regarding the cross section of the molded body of the electrode mixture in the electrode for all-solid-state batteries, select 10 particles of the active material whose outline can be confirmed in the image observed at 2000 times magnification using SEM, and perform the two-point method on the selected particles. Measure the longest diameter. Then, the average value (number average) of the longest diameters of all the measured particles is taken as the average particle diameter of the primary particles of the active material.

In addition, the average particle size of the primary particles of the solid electrolyte contained in the electrode material composite is the average particle size of the primary particles of the active material contained in the electrode material composite, except that the magnification for observation with SEM is changed to 30,000 times. This value is determined using the same method as the particle diameter.

As for the composition of the active material and the argyrodite solid electrolyte in the electrode material composite, the content of the argyrodite solid electrolyte is 2.5 parts by mass or more when the content of the active material is 100 parts by mass. It is preferably 8 parts by mass or more, more preferably 60 parts by mass or less, and more preferably 40 parts by mass or less. For example, the content of the argyrodite solid electrolyte can be set within the range of 2.5 to 60 parts by weight, 2.5 to 40 parts by weight, 8 to 60 parts by weight, and 8 to 40 parts by weight. If the electrode material composite has such a component composition, an electrode for an all-solid-state battery with a good balance between capacity and ionic conductivity can be formed.

The electrode material composite is manufactured by granulating active material particles and argyrodite-type sulfide-based solid electrolyte particles. There are no particular restrictions on the granulation method, and any known method can be applied, but it is necessary to adjust the stress that acts during granulation so that the argyrodite-type sulfide solid electrolyte can maintain its granular shape after granulation. For example, a desirable method for adjusting the stress that acts during granulation is to adjust a known mixer so as to generate Van der Waals force and electrostatic force due to collision and shearing action between materials.

The particles of the argyrodite-type sulfide solid electrolyte used to form the electrode material composite are measured using a particle size distribution measuring device (such as the particle size distribution measuring device "MT-3300EXII" manufactured by Micro Track Bell Co., Ltd.). The average particle diameter [50% diameter value (D ₅₀ ) of the volume-based integrated fraction when calculating the integral volume from particles with small particle size] is usually about 0.2 to 3 μm. Therefore, the argyrodite-type sulfide solid electrolyte of such size is made into the electrode material composite through granulation, and further, in the molded body of the electrode mixture formed using the electrode material composite, the argyrodite-type sulfide solid electrolyte is Particles of the active material and particles of the argyrodite-type sulfide-based solid electrolyte may be granulated by selecting conditions that can satisfy the primary particle diameter Rs.

The molded body of the electrode mixture included in the electrode for an all-solid-state battery can also contain an active material separately from the electrode material composite. As such an active material, the same active materials as those exemplified above for forming the electrode material composite can be used. However, when containing an active material separately from the electrode material composite, the amount of active material in the electrode material composite in the total 100% by mass of the active material in the electrode material composite and the active material that does not constitute the electrode material composite. The proportion of the active material is preferably 60% by mass or more. Note that it is not necessary to use an active material separately from the electrode material composite in the molded body of the electrode mixture, and the active material in the electrode material composite and the active material that does not constitute the electrode material composite may be used. A preferable upper limit value of the proportion of the active material in the electrode material composite in the total of 100% by mass is 100% by mass.

Further, the content of the active material in the electrode mixture (the active material contained in the electrode material composite and the active material used separately from the electrode material composite as necessary) is 55 to 75% by mass. It is preferable that Note that, when the active material has a reaction suppression layer, the content of the active material herein also includes the amount of the reaction suppression layer.

The molded body of the electrode mixture included in the electrode for an all-solid-state battery can also contain a solid electrolyte in addition to the solid electrolyte contained in the electrode material composite. Such solid electrolytes include, for example, the various sulfide-based solid electrolytes (argyrodite-type sulfide-based solid electrolytes and other sulfide-based solid electrolytes) listed above as those that can be used in the electrode material composite; Examples include the same as hydride solid electrolytes, halide solid electrolytes, and oxide solid electrolytes. The solid electrolyte used separately from the electrode material composite may be of the same type as that contained in the electrode material composite, or may be of a different type; Among electrolytes, sulfide-based solid electrolytes are more preferable because of their high lithium ion conductivity, and argyrodite-type sulfide-based solid electrolytes are preferred because they have particularly high lithium ion conductivity and high chemical stability. is even more preferable.

The content of the solid electrolyte in the electrode mixture (the solid electrolyte contained in the electrode material composite and the solid electrolyte used separately from the electrode material composite if necessary) is 25 to 50% by mass. is preferred.

The molded electrode mixture included in the electrode for an all-solid-state battery may contain a conductive additive such as carbon black or graphene, if necessary. When a conductive additive is contained in the molded electrode mixture, the content in the electrode mixture is preferably 2 to 10% by mass.

The molded body of the electrode mixture included in the electrode for an all-solid-state battery does not need to contain a resin binder, or may contain it. Examples of the resin binder include fluororesins such as polyvinylidene fluoride (PVDF). However, since the resin binder also acts as a resistance component in the molded electrode mixture, it is desirable that its amount be as small as possible. Therefore, in the molded body of the electrode mixture, it is preferable that the resin binder is not included, or if it is included, the content in the electrode mixture is 0.5% by mass or less. The content of the resin binder in the electrode mixture is more preferably 0.3% by mass or less, and even more preferably 0% by mass (that is, no resin binder is contained).

When a current collector is used in the electrode for an all-solid-state battery, metal foil, punched metal, net, expanded metal, foamed metal, carbon sheet, etc. can be used as the current collector. When using a metal current collector, it is preferable to use one made of aluminum or stainless steel when the electrode for all-solid-state batteries is the positive electrode, and one made of copper or nickel when the electrode for all-solid-state batteries is the negative electrode. is preferred.

The electrode mixture molded body is produced by, for example, compressing an electrode mixture prepared by mixing the electrode material composite and solid electrolyte with a conductive additive, a binder, etc., which are added as necessary, by pressure molding or the like. It can be formed by An all-solid-state battery electrode consisting only of a molded electrode mixture can be manufactured by such a method.

In the case of an electrode for an all-solid-state battery having a current collector, it can be manufactured by bonding a molded electrode mixture formed by the method described above to the current collector by pressing or the like.

Alternatively, an electrode mixture-containing composition is prepared by mixing the electrode mixture and a solvent, and this is applied onto a base material such as a current collector or a solid electrolyte layer facing the electrode, and after drying, press treatment is performed. By performing this step, a molded body of the electrode mixture may be formed.

It is preferable to select a solvent for the electrode mixture-containing composition that does not easily deteriorate the solid electrolyte. In particular, sulfide-based solid electrolytes and hydride-based solid electrolytes cause chemical reactions with minute amounts of water, so hydrocarbon solvents such as hexane, heptane, octane, nonane, decane, decalin, toluene, and xylene are typical. Preference is given to using non-polar aprotic solvents. In particular, it is more preferable to use a super dehydrated solvent with a water content of 0.001% by mass (10 ppm) or less. In addition, fluorinated solvents such as "Vertrell (registered trademark)" manufactured by Mitsui-DuPont Fluorochemicals, "Zeorolla (registered trademark)" manufactured by Nippon Zeon, and "Novec (registered trademark)" manufactured by Sumitomo 3M, Non-aqueous organic solvents such as , dichloromethane and diethyl ether can also be used.

The thickness of the electrode mixture molded body (in the case of an electrode having a current collector, the thickness of the electrode mixture molded body per one side of the current collector; the same applies hereinafter) is usually 50 μm or more, but From the viewpoint of increasing the capacity of the battery, the thickness is preferably 200 μm or more. Further, the thickness of the molded body of the electrode mixture is usually 3000 μm or less.

In addition, in the case of an electrode for an all-solid-state battery manufactured by forming an electrode mixture layer consisting of a molded body of the electrode mixture on a current collector using an electrode mixture-containing composition containing a solvent, The thickness of the electrode mixture layer (thickness per one side of the current collector) is preferably 50 to 1000 μm.

<All-solid battery>
The all-solid-state battery of the present invention has a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode is the above-described all-solid-state battery electrode of the present invention. be.

A cross-sectional view schematically showing an example of the all-solid-state battery of the present invention is shown in FIG. The all-solid-state battery 10 shown in FIG. A solid electrolyte layer 40 is enclosed between the solid electrolyte layer 30 and the solid electrolyte layer 40 .

The sealing can 60 is fitted into the opening of the outer can 50 via a gasket 70, and the open end of the outer can 50 is tightened inward, causing the gasket 70 to come into contact with the sealing can 60. The opening of the outer can 50 is sealed, so that the inside of the battery has a sealed structure.

Stainless steel can be used for the outer can and sealed can. In addition, polypropylene, nylon, etc. can be used as the material for the gasket, and if heat resistance is required due to battery usage, materials such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA) can be used. Fluororesin; polyphenylene ether ( PPE ); polysulfone (PSF); polyarylate (PAR); polyether sulfone (PES); polyphenylene sulfide (PPS); Resins can also be used. Furthermore, when the battery is used in applications requiring heat resistance, a glass hermetic seal can also be used to seal the battery.

Further, FIGS. 6 and 7 are diagrams schematically showing other examples of the all-solid-state battery of the present invention. FIG. 6 is a plan view of the all-solid-state battery, and FIG. 7 is a sectional view taken along line II in FIG. 6.

The all-solid-state battery 100 shown in FIGS. 6 and 7 houses an electrode body 200 consisting of a positive electrode, a solid electrolyte layer, and a negative electrode in a laminate film exterior body 500 configured with two metal laminate films. The outer periphery of the exterior body 500 is sealed by heat-sealing upper and lower metal laminate films. In addition, in FIG. 7, in order to avoid complicating the drawing, the layers that make up the laminate film exterior body 500 and the positive electrode, negative electrode, and solid electrolyte layer that make up the electrode body are not shown separately. .

The positive electrode of the electrode body 200 is connected to the positive external terminal 300 within the battery 100, and although not shown, the negative electrode of the electrode body 200 is also connected to the negative external terminal 400 within the battery 100. There is. The positive external terminal 300 and the negative external terminal 400 have one end pulled out to the outside of the laminate film exterior body 500 so that they can be connected to an external device or the like.

In the case of an all-solid-state battery using the all-solid-state battery electrode of the present invention as a positive electrode, the negative electrode may be the all-solid-state battery electrode of the present invention, or may be a negative electrode other than the all-solid-state battery electrode of the present invention. The negative electrode other than the electrode for an all-solid-state battery of the present invention is the same as the electrode for an all-solid-state battery of the present invention, except that a negative electrode active material that can be used in the electrode material composite is used instead of the electrode material composite. Electrode (negative electrode): A negative electrode consisting only of foil of various alloys (lithium alloys such as lithium-aluminum alloy, lithium-indium alloy, etc.) or metallic lithium that function as a negative electrode active material, or a negative electrode made of foil of metallic lithium, or the foil is placed on a current collector. Examples include a negative electrode laminated as an active material layer.

Further, in the case of an all-solid-state battery using the all-solid-state battery electrode of the present invention as a negative electrode, the positive electrode may be the all-solid-state battery electrode of the present invention, or may be a positive electrode other than the all-solid-state battery electrode of the present invention. The positive electrode other than the electrode for an all-solid-state battery of the present invention is the same as the electrode for an all-solid-state battery of the present invention, except that a positive electrode active material that can be used in the electrode material composite is used instead of the electrode material composite. Examples include the electrode (positive electrode) of the structure.

The solid electrolyte constituting the solid electrolyte layer of an all-solid-state battery includes the various sulfide-based solid electrolytes (argyrodite-type sulfide-based solid electrolyte and other sulfide-based solid electrolytes) listed above as those that can be used for the positive electrode. , a hydride solid electrolyte, a halide solid electrolyte, and an oxide solid electrolyte. However, in order to improve battery characteristics, it is preferable to contain a sulfide-based solid electrolyte, and it is more preferable to contain an argyrodite-type sulfide-based solid electrolyte.

The solid electrolyte layer may have a porous material such as a resin nonwoven fabric as a support.

A solid electrolyte layer is formed by compressing a solid electrolyte by pressure molding or the like; a solid electrolyte layer-forming composition prepared by dispersing a solid electrolyte in a solvent is applied onto a base material, a positive electrode, and a negative electrode, and dried. If necessary, it can be formed by a method of performing pressure molding such as press treatment.

The solvent used in the composition for forming a solid electrolyte layer is preferably one that does not easily deteriorate the solid electrolyte, and it is preferable to select a solvent that does not easily deteriorate the solid electrolyte. It is preferable to use the same one.

The thickness of the solid electrolyte layer is preferably 100 to 300 μm.

The positive electrode and the negative electrode can be used in a battery in the form of a laminated electrode body laminated with a solid electrolyte layer in between, or a wound electrode body in which this laminated electrode body is further wound.

Note that when forming the electrode body, it is preferable to press-mold the positive electrode, the negative electrode, and the solid electrolyte layer in a laminated state from the viewpoint of increasing the mechanical strength of the electrode body.

The all-solid-state battery of the present invention can be applied to the same uses as conventionally known all-solid-state batteries (all-solid primary batteries or all-solid secondary batteries).

Hereinafter, the present invention will be described in detail based on Examples. However, the following examples do not limit the present invention.

(Example 1)
<Preparation of electrode material composite for positive electrode>
LiCo _0.98 Al _0.01 Mg _0.01 O ₂ primary particles (positive electrode active material) with an average particle diameter of 5 μm and a layer made of LiNbO ₃ on the surface, and an argyrodite-type sulfide solid electrolyte (Li ₆ PS ₅ Cl) was granulated to produce a positive electrode material composite. The component composition of the positive electrode material composite was 100 parts by mass of the positive electrode active material and 20 parts by mass of the argyrodite-type sulfide solid electrolyte. Further, the amount of the layer made of LiNbO ₃ on the surface of LiCo _0.98 Al _0.01 Mg _0.01 O ₂ was 1 part by mass per 100 parts by mass of LiCo _0.98 Al _0.01 Mg _0.01 O ₂ . Furthermore, when granulating the positive electrode active material and the argyrodite-type sulfide-based solid electrolyte, the mixing conditions in the mixer were adjusted so that van der Waals force and electrostatic force were generated due to collision and shearing action between the materials.

<Preparation of positive electrode>
The positive electrode material composite, the same argyrodite-type sulfide solid electrolyte as that used in the positive electrode material composite, and acetylene black (conductivity aid) at a mass ratio of 20:5:1. They were mixed and kneaded well to prepare a positive electrode mixture. Next, 75 mg of the positive electrode mixture was placed in a powder molding mold with a diameter of 7.5 mm, and pressure molded using a press to produce a positive electrode consisting of a cylindrical positive electrode mixture molded body.

<Formation of solid electrolyte layer>
Next, 9.6 mg of the same sulfide-based solid electrolyte as that used for producing the positive electrode was placed on top of the positive electrode mixture molded body in the powder molding mold, and the molded body was press-molded using a press machine. A solid electrolyte layer was formed on the positive electrode mixture molded body to obtain a laminate of a positive electrode and a solid electrolyte layer.

<Preparation of laminated electrode body>
Lithium titanate (Li ₄ Ti ₅ O ₁₂ , negative electrode active material, average particle size: 1.3 μm), the same argyrodite-type sulfide solid electrolyte as used in the electrode material composite of the positive electrode, and graphene (conductive (auxiliary agent) in a mass ratio of 6:5:1 and kneaded thoroughly to prepare a negative electrode mixture. Next, 100 mg of the negative electrode mixture was put onto the solid electrolyte layer in the powder molding mold, and pressure molded using a press, so that the negative electrode mixture molded material was placed on the solid electrolyte layer. By forming a negative electrode consisting of the following, a laminated electrode body in which a positive electrode, a solid electrolyte layer, and a negative electrode were laminated was produced. The thicknesses of the positive electrode (positive electrode mixture molded body), solid electrolyte layer, and negative electrode (negative electrode mixture molded body) in the laminated electrode body were 750 μm, 100 μm, and 930 μm, respectively.

In addition, a plurality of laminated electrode bodies were produced, and the cross section of the positive electrode mixture molded body was observed with SEM for some of them, and an electrode material composite consisting of granules in the positive electrode mixture molded body was determined by the above method. It was confirmed that the argyrodite-type sulfide-based solid electrolyte in the electrode material composite was granular. Further, in the electrode material composite, the average particle diameter Ra of the primary particles of the positive electrode active material is 5 μm, the average particle diameter Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.6 μm, and the ratio of Ra/Rs is The value was 8.3.

<Assembling all-solid-state battery>
A laminated electrode body consisting of a positive electrode, a solid electrolyte layer, and a negative electrode is stacked on the inside of a stainless steel sealed can fitted with a polypropylene annular gasket so that the negative electrode side faces the inside of the sealed can, and then the stainless steel exterior is sealed. After covering the can, the open end of the outer can was caulked inward to seal it, thereby producing an all-solid-state battery with a diameter of about 9 mm.

(Example 2)
Primary particles (negative electrode active material) of lithium titanate (Li ₄ Ti ₅ O ₁₂ ) with an average particle size of 1.3 μm and argyrodite-type sulfide solid electrolyte (Li ₆ PS ₅ Cl) with an average particle size of 0.6 μm. ) was granulated to produce a negative electrode material composite. The component composition of the negative electrode material composite was 100 parts by mass of the negative electrode active material and 40 parts by mass of the argyrodite-type sulfide solid electrolyte. Furthermore, when granulating the negative electrode active material and the argyrodite-type sulfide-based solid electrolyte, the mixing conditions in the mixer were adjusted so as to generate Van der Waals force and electrostatic force due to collision and shearing action between the materials.

The negative electrode material composite, the same argyrodite-type sulfide solid electrolyte as that used in the negative electrode material composite, and graphene (conductive additive) in a mass ratio of 8:2:1. A laminated electrode body was prepared in the same manner as in Example 1, except that a negative electrode mixture prepared by mixing and thoroughly kneading was used. A solid-state battery was fabricated.

In addition, a plurality of laminated electrode bodies were produced, and the cross sections of the positive electrode mixture molded body and the negative electrode mixture molded body were observed using SEM for some of them, and the positive electrode mixture molded body and the negative electrode mixture molded body were observed by the above method. The presence of an electrode material composite consisting of granules in the molded body, an argyrodite-type sulfide solid electrolyte in the electrode material composite of the positive electrode mixture molded body, and an electrode related to the negative electrode mixture molded body. It was confirmed that each of the argyrodite-type sulfide-based solid electrolytes in the material composite was granular. In addition, in the electrode material composite in the positive electrode mixture molded body, the average particle size Ra of the primary particles of the positive electrode active material is 5 μm, and the average particle size Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.6 μm. The value of Ra/Rs was 8.3. Furthermore, in the electrode material composite in the negative electrode mixture molded body, the average particle size Ra of the primary particles of the negative electrode active material is 1.3 μm, and the average particle size Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.5 μm. 6 μm, and the value of Ra/Rs was 2.2.

(Example 3)
A positive electrode material composite was produced in the same manner as in Example 1, except that the amount of the argyrodite-type sulfide solid electrolyte was changed to 48 parts by mass relative to 100 parts by mass of the positive electrode active material. The same procedure as in Example 1 was used except that a positive electrode mixture prepared by mixing the positive electrode material composite and acetylene black (conductive support agent) at a mass ratio of 26:1 and kneading well was used. A laminated electrode body was produced in the same manner, and an all-solid-state battery was produced in the same manner as in Example 1 except that this laminated electrode body was used.

In addition, a plurality of laminated electrode bodies were produced, and the cross section of the positive electrode mixture molded body was observed with SEM for some of them, and an electrode material composite consisting of granules in the positive electrode mixture molded body was determined by the above method. It was confirmed that the argyrodite-type sulfide-based solid electrolyte in the electrode material composite was granular. Further, in the electrode material composite, the average particle diameter Ra of the primary particles of the positive electrode active material is 5 μm, the average particle diameter Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.6 μm, and the ratio of Ra/Rs is The value was 8.3.

(Example 4)
The positive electrode active material was made of primary particles of LiCo _0.98 Al _0.01 Mg _0.01 O ₂ with an average particle size of 3 μm and a layer made of LiNbO ₃ on the surface (the amount of the layer made of LiNbO ₃ on the surface of LiCo _0.98 Al _0.01 Mg _0.01 O ₂ An electrode material composite for a positive electrode was prepared in the same manner as in Example 1, except that the amount was changed to 1 part by mass per 100 parts by mass of LiCo _0.98 Al _0.01 Mg _0.01 O ₂ . A laminated electrode body was produced in the same manner as in Example 1, except that the electrode body was used, and an all-solid-state battery was produced in the same manner as in Example 1, except that this laminated electrode body was used.

In addition, a plurality of laminated electrode bodies were produced, and the cross section of the positive electrode mixture molded body was observed with SEM for some of them, and an electrode material composite consisting of granules in the positive electrode mixture molded body was determined by the above method. It was confirmed that the argyrodite-type sulfide-based solid electrolyte in the electrode material composite was granular. Furthermore, in the electrode material composite, the average particle diameter Ra of the primary particles of the positive electrode active material is 3 μm, the average particle diameter Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.6 μm, and the ratio of Ra/Rs is The value was 5.

(Example 5)
A positive electrode material composite was produced in the same manner as in Example 1, except that the amount of the argyrodite-type sulfide solid electrolyte was changed to 37 parts by mass relative to 100 parts by mass of the positive electrode active material. Then, the same argyrodite-type sulfide-based solid electrolyte as that used in the positive electrode material composite and acetylene black (conductive additive) were mixed in a mass ratio of 24:5:1 and kneaded well. A laminated electrode body was produced in the same manner as in Example 1, except that the prepared positive electrode mixture was used, and an all-solid-state battery was produced in the same manner as in Example 1, except that this laminated electrode body was used.

In addition, a plurality of laminated electrode bodies were produced, and the cross section of the positive electrode mixture molded body was observed with SEM for some of them, and an electrode material composite consisting of granules in the positive electrode mixture molded body was determined by the above method. It was confirmed that the argyrodite-type sulfide-based solid electrolyte in the electrode material composite was granular. Further, in the electrode material composite, the average particle diameter Ra of the primary particles of the positive electrode active material is 5 μm, the average particle diameter Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.6 μm, and the ratio of Ra/Rs is The value was 8.3.

(Example 6)
The positive electrode active material is made of primary particles of LiCo _0.3 Ni _0.7 O ₂ having an average particle diameter of 5 μm and a layer made of LiNbO ₃ on the surface (the amount of the layer made of LiNbO ₃ on the surface of LiCo _0.3 Ni _0.7 O ₂ is LiCo _0.3 An electrode material composite for a positive electrode was prepared in the same manner as in Example 1, except that the amount of Ni _0.7 O ₂ was changed to 1 part by mass per 100 parts by mass, and the electrode material composite for a positive electrode was used. A laminated electrode body was produced in the same manner as in Example 1, and an all-solid-state battery was produced in the same manner as in Example 1 except that this laminated electrode body was used.

In addition, a plurality of laminated electrode bodies were produced, and the cross section of the positive electrode mixture molded body was observed with SEM for some of them, and an electrode material composite consisting of granules in the positive electrode mixture molded body was determined by the above method. It was confirmed that the argyrodite-type sulfide-based solid electrolyte in the electrode material composite was granular. Further, in the electrode material composite, the average particle diameter Ra of the primary particles of the positive electrode active material is 5 μm, the average particle diameter Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.6 μm, and the ratio of Ra/Rs is The value was 8.3.

(Example 7)
The positive electrode active material was made _of primary particles of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (LiNi _1/3 Co _1/3 Mn _1/3 Same as Example 1 except that the amount of the layer made of LiNbO ₃ on the surface of O ₂ was changed to 1 part by mass per 100 parts by mass of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ A laminated electrode body was fabricated in the same manner as in Example 1, except that an electrode material composite for a positive electrode was prepared in the same manner as in Example 1, and this laminated electrode body was used. An all-solid-state battery was produced in the same manner as in Example 1.

In addition, a plurality of laminated electrode bodies were produced, and the cross section of the positive electrode mixture molded body was observed with SEM for some of them, and an electrode material composite consisting of granules in the positive electrode mixture molded body was determined by the above method. It was confirmed that the argyrodite-type sulfide-based solid electrolyte in the electrode material composite was granular. Further, in the electrode material composite, the average particle diameter Ra of the primary particles of the positive electrode active material is 5 μm, the average particle diameter Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.6 μm, and the ratio of Ra/Rs is The value was 8.3.

(Example 8)
A positive electrode material composite was prepared in the same manner as in Example 1, except that the argyrodite-type sulfide solid electrolyte was changed to Li ₁₀ GeP ₂ S ₁₂ with an average particle size of 0.6 μm, and this positive electrode A positive electrode was prepared in the same manner as in Example 1, except that the material composite was used and the solid electrolyte added separately from the positive electrode material composite was changed to Li ₁₀ GeP ₂ S ₁₂ with an average particle size of 0.6 μm. A mixture was prepared. Then, the same procedure as in Example 1 was carried out except that this positive electrode mixture was used and the solid electrolyte used for the solid electrolyte layer and the negative electrode mixture was changed to Li ₁₀ GeP ₂ S ₁₂ with an average particle size of 0.6 μm. An all-solid-state battery was produced in the same manner as in Example 1 except that a laminated electrode body was produced using this laminated electrode body.

In addition, a plurality of laminated electrode bodies were produced, and the cross section of the positive electrode mixture molded body was observed with SEM for some of them, and an electrode material composite consisting of granules in the positive electrode mixture molded body was determined by the above method. It was confirmed that the argyrodite-type sulfide-based solid electrolyte in the electrode material composite was granular. Further, in the electrode material composite, the average particle diameter Ra of the primary particles of the positive electrode active material is 5 μm, the average particle diameter Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.6 μm, and the ratio of Ra/Rs is The value was 8.3.

(Example 9)
An electrode material composite for a positive electrode was prepared in the same manner as in Example 1, except that the argyrodite-type sulfide-based solid electrolyte was changed to Li _4.9 PS _4.2 Cl _0.9 Br _0.9 with an average particle size of 0.6 μm. Example 1 except that the electrode material composite for the positive electrode was used and the solid electrolyte added separately from the electrode material composite for the positive electrode was changed to Li _4.9 PS _4.2 Cl _0.9 Br _0.9 with an average particle size of 0.6 μm. A positive electrode mixture was prepared in the same manner. The same procedure as Example 1 was performed except that this positive electrode mixture was used and the solid electrolyte used for the solid electrolyte layer and the negative electrode mixture was changed to Li _4.9 PS _4.2 Cl _0.9 Br _0.9 with an average particle size of 0.6 μm. A laminated electrode body was produced in the same manner, and an all-solid-state battery was produced in the same manner as in Example 1 except that this laminated electrode body was used.

In addition, a plurality of laminated electrode bodies were produced, and the cross section of the positive electrode mixture molded body was observed with SEM for some of them, and an electrode material composite consisting of granules in the positive electrode mixture molded body was determined by the above method. It was confirmed that the argyrodite-type sulfide-based solid electrolyte in the electrode material composite was granular. Further, in the electrode material composite, the average particle diameter Ra of the primary particles of the positive electrode active material is 5 μm, the average particle diameter Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.6 μm, and the ratio of Ra/Rs is The value was 8.3.

(Example 10)
A laminated electrode body was produced in the same manner as in Example 1, except that the negative electrode active material was changed to graphite with an average particle size of 15 μm; A battery was created.

In addition, a plurality of laminated electrode bodies were produced, and the cross section of the positive electrode mixture molded body was observed with SEM for some of them, and an electrode material composite consisting of granules in the positive electrode mixture molded body was determined by the above method. It was confirmed that the argyrodite-type sulfide-based solid electrolyte in the electrode material composite was granular. Further, in the electrode material composite, the average particle diameter Ra of the primary particles of the positive electrode active material is 5 μm, the average particle diameter Rs of the primary particles of the argyrodite-type sulfide solid electrolyte is 0.6 μm, and the ratio of Ra/Rs is The value was 8.3.

(Comparative example 1)
The same primary particles (positive electrode active material) of LiCo _0.98 Al _0.01 Mg _0.01 O ₂ having a layer made of LiNbO ₃ on the surface as used in Example 1, and the same argyrodite-type sulfide as used in Example 1. A positive electrode mixture was prepared by mixing a solid electrolyte and acetylene black (conductivity aid) at a mass ratio of 17:8:1. An all-solid-state battery was produced in the same manner as in Example 1 except that this positive electrode mixture was used. In addition, in the positive electrode mixture of Comparative Example 1, the positive electrode active material and the solid electrolyte were not granulated.

(Comparative example 2)
The positive electrode active material was made of primary particles of LiCo _0.98 Al _0.01 Mg _0.01 O ₂ with an average particle size of 3 μm and a layer made of LiNbO ₃ on the surface (the amount of the layer made of LiNbO ₃ on the surface of LiCo _0.98 Al _0.01 Mg _0.01 O ₂ An all-solid-state battery was produced in the same manner as in Comparative Example 1, except that the amount of LiCo _0.98 Al _0.01 Mg _0.01 O ₂ was changed to 1 part by mass per 100 parts by mass).

(Comparative example 3)
The positive electrode active material is made of primary particles of LiCo _0.3 Ni _0.7 O ₂ having an average particle diameter of 5 μm and a layer made of LiNbO ₃ on the surface (the amount of the layer made of LiNbO ₃ on the surface of LiCo _0.3 Ni _0.7 O ₂ is LiCo _0.3 An all-solid-state battery was produced in the same manner as Comparative Example 1, except that the amount of Ni _0.7 O ₂ was changed to 1 part by mass per 100 parts by mass.

(Comparative example 4)
An all-solid-state battery was produced in the same manner as Comparative Example 1, except that the negative electrode active material was changed to graphite having an average particle diameter of 15 μm.

(Comparative example 5)
A positive electrode material composite was prepared in the same manner as in Example 1, except that the positive electrode active material and the argyrodite-type sulfide solid electrolyte were mixed under conditions that applied stress to the extent that a mechanochemical reaction occurred. A laminated electrode body was produced in the same manner as in Example 1, except that this positive electrode material composite was used, and an all-solid-state battery was produced in the same manner as in Example 1, except that this laminated electrode body was used.

In addition, a plurality of laminated electrode bodies were manufactured, and the cross section of the positive electrode mixture molded body was observed using SEM for some of them, and it was found that the argyrodite-type sulfide-based solid electrolyte in the electrode material composite could not maintain its granularity and was found to be a solid electrolyte. It was confirmed that this is a continuous phase. Furthermore, in the electrode material composite, the average particle diameter Ra of the primary particles of the positive electrode active material was 5 μm.

The load characteristics of the all-solid-state batteries of Examples and Comparative Examples were evaluated by the following method.

For each all-solid-state battery of Examples and Comparative Examples, constant current charging was performed at a current value of 0.05C until the voltage reached 2.6V, and then constant voltage charging was performed until the current value reached 0.01C. The initial capacity was measured by discharging at a current value of 0.05C until the voltage reached 1.5V.

After the initial capacity measurement, each battery was charged and discharged under the same conditions as the initial capacity measurement, except that the current value during discharge was changed to 1C, and the 1C discharge capacity was measured. Then, the value obtained by dividing the 1C discharge capacity of each battery by the initial capacity was expressed as a percentage to determine the capacity retention rate, and the load characteristics of each battery were evaluated.

The above evaluation results were combined with the configuration of the electrode material composite in the positive electrode (positive electrode mixture molded body) and the electrode material composite (Example 2 only) in the negative electrode (negative electrode mixture molded body) related to the all-solid-state battery. It is shown in Table 1. In addition, in Table 1, the capacity retention rate at the time of load characteristic evaluation is shown as a relative value when the value of Comparative Example 1 is set as 100.

As shown in Table 1, a molded article of an electrode mixture containing an electrode material composite consisting of granules of an active material and an argyrodite-type sulfide-based solid electrolyte, and in which the argyrodite-type sulfide-based solid electrolyte is in the form of granules. The all-solid-state batteries of Examples 1 to 10 using electrodes having the above-mentioned electrode material composite, the batteries of Comparative Examples 1 to 4 using electrodes having molded electrode mixtures not containing the electrode material composite, and the batteries of Comparative Examples 1 to 4 using electrodes having an electrode material composite containing no argyrodite-type sulfide. Compared to the battery of Comparative Example 5, which uses an electrode having a molded electrode material composite containing an electrode material composite in which the solid electrolyte loses its granularity and becomes a continuous phase, capacity maintenance during load characteristic evaluation was improved. It had a high rate and excellent load characteristics.

In particular, the all-solid-state battery of Example 2, in which the positive electrode and the negative electrode have electrodes each having a molded body of an electrode mixture containing the electrode material composite, has a molded body of an electrode mixture containing the electrode material composite. The load characteristics were better than the batteries of Examples 1 and 3 to 10, which had only the positive electrode.

The present application can be implemented in forms other than those described above without departing from the spirit thereof. The embodiments disclosed in this application are merely examples, and the present invention is not limited thereto. The scope of this application shall be interpreted with priority given to the description of the attached claims rather than the description of the above-mentioned specification, and all changes within the scope of equivalency to the claims are included within the scope of the claims. It is something that can be done.

1 Electrode material composite 1a, 3 Primary particles of active material 1b Argyrodite-type sulfide solid electrolyte 2 Solid electrolyte 10, 100 All-solid-state battery 20 Positive electrode 30 Negative electrode 40 Solid electrolyte layer 50 Exterior can 60 Sealing can 70 Gasket 200 Electrode body 300 Positive external terminal 400 Negative external terminal 500 Laminated film exterior body

Claims (6)

An all-solid battery electrode comprising a molded electrode mixture,
The electrode mixture includes an electrode material composite,
The electrode material composite consists of a granule containing an active material and a solid electrolyte,
An electrode for an all-solid-state battery, wherein the solid electrolyte includes a granular argyrodite-type sulfide-based solid electrolyte. The ratio Ra/Rs of the average particle diameter Ra of the primary particles of the active material contained in the electrode material composite and the average particle diameter Rs of the primary particles of the solid electrolyte contained in the electrode material composite is 2 to 50. The all-solid battery electrode according to claim 1, wherein the electrode has a molecular weight of 50. The electrode for an all-solid-state battery according to claim 1 or 2, wherein the primary particles of the active material contained in the electrode material composite have an average particle size Ra of 1 to 25 μm. The electrode for an all-solid battery according to any one of claims 1 to 3, wherein the average particle diameter Rs of the primary particles of the solid electrolyte contained in the electrode material composite is 0.2 to 3 μm. Claims 1 to 4, wherein the content of the argyrodite solid electrolyte contained in the electrode material composite is 2.5 to 60 parts by mass based on 100 parts by mass of the active material contained in the electrode material composite. The electrode for an all-solid-state battery according to any one of the above. An all-solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode,
An all-solid-state battery, wherein at least one of the positive electrode and the negative electrode is the all-solid-state battery electrode according to any one of claims 1 to 5.

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