SOLID-STATE LITHIUM-ION SECONDARY BATTERY

Abstract

Solid-state lithium-ion secondary battery, wherein an anode comprises an anode active material, an electrically conductive material, and comprises a solid electrolyte; wherein the anode active material comprises at least one active material selected from the group consisting of a metal capable of forming an alloy with Li, an oxide of the metal, and an alloy of the metal and Li; and where the solid electrolyte comprises particles with a specific BET surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g, wherein an A value for the solid electrolyte particles obtained by the following formula (1) is in a range of 12.4 to 56.7: A = specific BET surface area ( m 2 / g ) × average diameter D 50 ( μ m ) × density ( g / cm 3 )

Description

Technical area

[0001] The disclosure relates to a solid-state lithium-ion secondary battery or accumulator. State of the art

[0002] An active material (an alloy-based active material) comprising a metal such as Si, which is capable of forming an alloy with Li, exhibits a high theoretical capacity per volume compared to carbon-based anode active materials. Therefore, a lithium-ion battery using such an alloy-based active material in its anode has been proposed.

[0003] Patent Literature 1 discloses a negative electrode mixture for a secondary battery, the mixture comprising, as a negative electrode active material powder, an alloy-based active material with an average particle diameter of 10 μm or less. Patent Literature 1 also discloses an all-solid-state lithium-ion battery having an anode layer containing the negative electrode active material powder.

[0004] Furthermore, the published patent applications of Patent Literature 2 and Patent Literature 3 disclose prior art solid-state secondary batteries. Reference sources Patent Literature 1: JP 2013-069416 A Patent literature 2: US 2015 / 0147660 A1 Patent literature 3: WO 2013 / 137224 A1 Summary of the inventionTechnical problem

[0005] However, the all-solid-state lithium-ion secondary battery disclosed in Patent Literature 1, which uses an alloy-based active material as an anode active material, exhibits a low capacity retention rate when repeating charge-discharge cycles.

[0006] Due to this circumstance, an object of the disclosed embodiments is to provide an all-solid-state lithium ion secondary battery comprising an anode containing at least one active material selected from the group consisting of a metal capable of forming an alloy with Li, an oxide of the metal, and an alloy of the metal and Li, and having excellent cycling characteristics. Solution to the problem

[0007] The solid-state lithium-ion secondary battery of the disclosed embodiments is a solid-state lithium-ion secondary battery, wherein an anode contains an anode active material, an electrically conductive material, and a solid electrolyte; wherein the anode active material contains at least one active material selected from the group consisting of a metal capable of forming an alloy with Li, an oxide of the metal, and an alloy of the metal and Li; and wherein the solid electrolyte comprises particles having a BET specific surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g is.

[0008] For the solid electrolyte of the all-solid-state lithium-ion secondary battery of the disclosed embodiments, a value A obtained by the following formula (1) is in a range of 12.4 to 56.7: A=specific BET surface area (m2 / g) × average diameter D50 (μm) × density (g / cm3)

[0009] The anode active material of the all-solid-state lithium-ion secondary battery of the disclosed embodiments may contain at least one active material selected from the group consisting of elemental silicon and an alloy of Si and Li.

[0010] The solid electrolyte of the all-solid-state lithium-ion secondary battery of the disclosed embodiments may be a sulfide solid electrolyte.

[0011] The electrically conductive material of the all-solid-state lithium-ion secondary battery of the disclosed embodiments may be at least one carbonaceous material selected from the group consisting of carbon black, carbon nanotubes, and carbon nanofibers. Advantageous effects of the invention

[0012] According to the disclosed embodiments, the all-solid-state lithium-ion secondary battery can be provided, the battery comprising an anode containing at least one active material selected from the group consisting of a metal capable of forming an alloy with Li, an oxide of the metal, and an alloy of the metal and Li, as an anode active material, and having excellent cycling characteristics. Short description of the drawing Fig. 1 is a schematic view of an example of the structure of an all-solid-state lithium-ion secondary battery. Description of the embodiments

[0013] The solid-state lithium-ion secondary battery according to the disclosed embodiments is a solid-state lithium-ion secondary battery, wherein an anode contains an anode active material, an electrically conductive material, and a solid electrolyte; wherein the anode active material comprises at least one active material selected from the group consisting of a metal capable of forming an alloy with Li, an oxide of the metal, and an alloy of the metal and Li; and wherein the solid electrolyte comprises particles having a BET specific surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g is.

[0014] The metal suitable for alloying with Li exhibits low ionic and electronic conductivity. Therefore, when the metal is used as an anode active material, an electrically conductive material and a solid electrolyte are generally incorporated into the anode in combination with the anode active material.

[0015] When the metal capable of forming an alloy with Li (hereinafter, the metal capable of forming an alloy with Li may be referred to as M) is used as the anode active material, the reaction represented by the following formula (2), that is, a so-called electrochemical alloying reaction, is initiated in the anode when the lithium-ion secondary battery is charged: xLi + + xe - + yM → Li x M y Formula (2)

[0016] When discharging the lithium-ion secondary battery, as shown by the following formula (3), an extraction reaction of Li ions is initiated from the alloy of Si and Li in the anode: Li x M y → xLi + + xe - + yM formula (3)

[0017] The lithium-ion secondary battery using the metal capable of forming an alloy with Li as the anode active material undergoes a large volume change associated with the Li insertion / extraction reactions represented by formulas (2) and (3).

[0018] Patent Literature 1 describes that the average particle diameter of a powder of an ion-conductive material (solid electrolyte) is preferably small because the contact points between the anode active material and the solid electrolyte increase as the average particle diameter decreases.

[0019] However, it was found that in the case of the all-solid-state lithium-ion secondary battery including the anode containing an anode active material, an electrically conductive material and a solid electrolyte, the capacity retention rate of the battery may deteriorate especially in the initial stage if the average particle diameter of the solid electrolyte is too small.

[0020] However, when the average particle diameter of the solid electrolyte in the anode is reduced (i.e., when the specific surface area is increased), which is advantageous from the standpoint of ionic conductivity, the electrically conductive material is likely to adsorb on the surface of the solid electrolyte. Therefore, the electrically conductive material is unevenly distributed in the anode, narrowing the electrically conductive path in the area where the amount of electrically conductive material is small.

[0021] As just described, in the area where the electrically conductive path is narrow, the electrically conductive path is gradually cut off due to repeated volume changes of the alloy-based active material associated with charging and discharging. Consequently, the capacity retention rate of the all-solid-state lithium-ion secondary battery is expected to deteriorate.

[0022] In the all-solid-state lithium-ion secondary battery of the disclosed embodiments, by using solid electrolyte particles having a specific BET surface area within a specific range in the anode, uneven distribution of the electrically conductive material can be prevented while maintaining excellent ionic conductivity. Therefore, it is expected that the capacity retention rate can be maintained high even when the alloy-based active material is used as the anode active material.

[0023] Hereinafter, the all-solid-state lithium ion secondary battery of the disclosed embodiments will be described in detail. 1. Solid-state lithium-ion secondary battery

[0024] The structure of the all-solid-state lithium-ion secondary battery of the disclosed embodiments is not particularly limited as long as the battery functions as a secondary battery. As in Fig.1, the all-solid-state lithium-ion secondary battery of the disclosed embodiments typically includes a cathode 2, an anode 3, and a solid electrolyte layer 1 disposed between the cathode 2 and the anode 3, which form a cathode-solid electrolyte layer-anode unit 101. The cathode-solid electrolyte layer-anode unit 101 is a unit of elements having the following arrangement structure: the cathode, the solid electrolyte layer, and the anode are arranged in this order; they may be directly connected or indirectly connected through a part made of a different material; and a part made of a different material may be connected to one or both of the opposite sides of the cathode at the position where the solid electrolyte layer is present (the outer side and the outer side, respectively).outside of the cathode) and the opposite side of the anode at the location where the solid electrolyte layer is present (the outer side or outside of the anode).

[0025] By connecting other elements, such as a current collector, to the cathode-solid electrolyte layer-anode unit 101, a cell is obtained, which is a functional unit of an all-solid-state battery. The cell can be used as an all-solid-state lithium-ion battery as is, or a plurality of the cells can be electrically connected to form a unit cell and used as the all-solid-state lithium-ion battery of the disclosed embodiments.

[0026] For the cathode-solid electrolyte layer-anode unit, generally the thicknesses of the cathode and the anode are in a range of about 0.1 µm to about 10 mm, and the thickness of the solid electrolyte layer is in a range of about 0.01 µm to about 1 mm. 1-1. Anode

[0027] The anode of the solid-state lithium-ion secondary battery of the disclosed embodiments comprises an anode active material, an electrically conductive material, and a solid electrolyte. (anode active material)

[0028] The anode active material comprises at least one active material selected from the group consisting of a metal capable of forming an alloy with Li, an oxide of the metal, and an alloy of the metal and Li.

[0029] The metal capable of forming an alloy with Li is not particularly limited, as long as it is a metal capable of inserting / extracting Li ions according to the so-called electrochemical alloying reactions represented by formulas (2) and (3). As the metal element capable of forming an alloy with Li, examples include, but are not limited to, Mg, Ca, Al, Si, Ge, Sn, Pb, Sb, and Bi. Among these, the metal capable of forming an alloy with Li may be Si, Ge, or Sn, and may be Si. In the disclosed embodiments, the term "metal" is used as a concept that includes the following terms used for the general classification of elements: "metal" and "semimetal."

[0030] The oxide of the metal capable of forming an alloy with Li is such an oxide that produces M in the anode upon charging the lithium-ion secondary battery through the electrochemical reaction represented by the following formula (4): xLi + + xe - + yMO → Li x O y + yM formula (4)

[0031] Through the electrochemical reaction represented by formula (2) or (3), Li can be inserted into and extracted from M produced from the oxide of the metal capable of forming an alloy with Li according to formula (4). Therefore, the oxide of the metal capable of forming an alloy with Li is generally classified in the category of alloy-based active materials. With the metal capable of forming an alloy with Li, the oxide of the metal capable of forming an alloy with Li has the property of undergoing a large volume change associated with the Li insertion / extraction reactions.

[0032] As the oxide of the metal capable of forming an alloy with Li, examples include, but are not limited to, SiO and SnO. The oxide may be SiO.

[0033] The percentage of the anode active material in the anode is not particularly limited. For example, it can be 40 mass% or more, in a range of 50 mass% to 90 mass%, or in a range of 50 mass% to 70 mass%.

[0034] The shape of the metal capable of forming an alloy with Li, the oxide of the metal, and the alloy of the metal and Li are not particularly limited. Examples of the shape include, but are not limited to, a particle shape and a film shape. (solid electrolyte)

[0035] The solid electrolyte is particles with a specific BET surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g. As described above, by using the particles with a BET specific surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g as the solid electrolyte in the anode, the capacity retention rate of the lithium-ion secondary battery can be kept high.

[0036] As used herein, BET specific surface area means a specific surface area calculated by the BET method using the monomolecular adsorption amount of the gas adsorbed on the surface of a substance.

[0037] If the specific BET surface area is more than 19.7 m 2 / g, the electrically conductive material adsorbs on the surface of the solid electrolyte, and the electrically conductive material is unevenly distributed in the anode. Therefore, the electron-conductive path is locally narrowed, resulting in a reduction in the capacity retention rate. If the BET specific surface area is less than 1.8 m 2 / g, the number of contact points with the anode active material decreases and therefore cannot maintain an ion-conductive path.

[0038] In order to keep the ion-conductive path and the electron-conductive path in balance, the specific BET surface area of ​​the solid electrolyte particles can be increased from 3.0 m 2 / g up to 9.0 m 2 / g.

[0039] For the solid electrolyte particles, the value A obtained by the following formula (1) is in a range of 12.4 to 56.7: A=specific BET surface area (m2 / g) × average diameter D50 (μm) × density (g / cm3)

[0040] In the formula (1), the mean diameter means such a diameter that the accumulated volume of the particles is half (50%) of the total volume when the particle diameters of the particles are arranged in ascending order.

[0041] The value A is a parameter that indicates the shape of the particles. If the particle shape has a perfect spherical shape, the value A is 6.0. In the disclosed embodiments, the shape means a shape that includes fine convexoconcaves on the particle surface and open pores present inside the particles.

[0042] In the case where the specific BET surface area of ​​the solid electrolyte particles in the anode is in a range of 1.8 m 2 / g up to 19.7 m 2 / g, the capacity retention rate is increased by setting the A value within a range of 12.4 to 56.7. It is difficult to manufacture solid electrolyte particles having an A value of less than 12.4. However, since the capacity retention rate tends to increase as the A value approaches 6.0, it is believed that the electrically conductive material is less likely to be present on the surface of the solid electrolyte particles as the shape of the particles approaches a perfect spherical shape.

[0043] The raw material or starting material for the solid electrolyte particles is not particularly limited, as long as it is a starting material applicable to the all-solid-state lithium-ion secondary battery. For example, an oxide-based non-crystalline solid electrolyte, a sulfide-based non-crystalline solid electrolyte, a crystalline oxide, or a crystalline nitride, all of which have high Li-ion conductivity, are preferably used as the starting material.

[0044] As the oxide-based, non-crystalline solid electrolyte, examples include, but are not limited to, Li 2 WHETHER 2 O 3 -P 2 O 3 and Li 2 O-SiO 2 . As the sulfide-based non-crystalline solid electrolyte, examples include, but are not limited to, Li 2 S-SiS 2 , LiI-Li 2 S-SiS 2 , LiI-Li 2 SP 2 S5 , LiI-Li 3 PO 4 -P 2 S 5 and Li 2 SP 2 S 5 . As the crystalline oxide and the crystalline nitride, examples include, but are not limited to, LiI, Li 3 N, Li 5 La 3 Ta 2 O 12 , Li 7 La 3 Zr 2 O 12 , Li 6 BaLa 2 Ta 2 O 12 , Li 3 PO( 4-3 / 2w) N w (w < 1) and Li 3,6 Si 0,6 P 0,4 O 4 .

[0045] The percentage of solid electrolyte in the anode is not particularly limited. For example, it can be 10 mass% or more, in a range of 20 mass% to 50 mass%, or in a range of 25 mass% to 45 mass%. (Electrically conductive material)

[0046] The electrically conductive material is not particularly limited, as long as it is an electrically conductive material applicable to the anode of the all-solid-state lithium-ion secondary battery. As the starting material for the electrically conductive material, examples include, but are not limited to, at least one carbonaceous material selected from the group consisting of carbon black (e.g., acetylene black and furnace black), carbon nanotubes, and carbon fiber.

[0047] From the standpoint of electronic conductivity, the starting material may be at least one carbon-like material selected from the group consisting of carbon nanotubes and carbon fiber. The carbon nanotubes and carbon fiber may be vapor-grown carbon fiber (VGCF).

[0048] The percentage of electrically conductive material in the anode is not particularly limited. For example, it can be 1.0 mass% or more, in a range of 1.0 mass% to 12.0 mass%, or in a range of 2.0 mass% to 10.0 mass%.

[0049] In addition to the above-mentioned components, the anode may contain other components such as a binder. This is because the use of particles with a BET specific surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g as the solid electrolyte, the presence or absence of other components such as a binder in the anode prevents, does not affect or influence the effect that the electrically conductive material is unevenly distributed on the solid electrolyte surface.

[0050] Examples of the binder include, but are not limited to, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), butylene rubber (BR), styrene-butadiene rubber (SBR), polyvinyl butyral (PVB), and acrylic resin. The binder may be polyvinylidene fluoride (PVdF).

[0051] Since a high energy density is obtained, the anode of the disclosed embodiments may be an anode in which the percentage of components other than the anode active material is small. 1-2. Cathode

[0052] The cathode is not particularly limited, as long as it is a cathode that functions as the cathode of the all-solid-state lithium-ion secondary battery. Generally, the cathode comprises a Li-containing cathode active material. If necessary, the cathode contains other components such as a binder, a solid electrolyte, and an electrically conductive material.

[0053] In the disclosed embodiments, the Li-containing cathode active material is not particularly limited as long as it is an active material containing a Li element. A substance can be used as the cathode active material without particular limitation as long as it functions as the cathode active material in an electrochemical reaction with the anode active material and promotes an electrochemical reaction that promotes Li ion transfer. Likewise, a substance known as the cathode active material of a lithium-ion battery can be used in the disclosed embodiments.

[0054] The starting material for the cathode active material is not particularly limited as long as it is a starting material applicable to the all-solid-state lithium-ion secondary battery. Examples of the starting material include, but are not limited to, lithium cobaltate (LiCoO 2), lithium nickelate (LiNiO 2 ), lithium manganate (LiMn 2 O 4 ), a Li-Mn spinel substituted with another element, which is replaced by Li 1+x No 1 / 3 Mn 1 / 3 Co 1 / 3 O 2 , Li 1+x Mn 2-x-y M y O 4 (where M is one or more elements selected from Al, Mg, Co, Fe, Ni and Zn), lithium titanate (Li x TiO y ) and lithium metal phosphate (LiMPO 4 , M = Fe, Mn, Co, Ni, etc.).

[0055] The cathode active material may comprise a coating layer that exhibits lithium ion conductivity and contains a substance that is not fluidized even when in contact with the active material or the solid electrolyte. Examples of the substance include, but are not limited to, LiNbO 3 , Li 4 Ti 5 O 12 and Li 3 PO4 .

[0056] The shape of the cathode active material is not particularly limited. It can be a film or a particle form.

[0057] The percentage of the cathode active material in the cathode is not particularly limited. For example, it can be 60 mass% or more, in a range of 70 mass% to 95 mass%, or in a range of 80 mass% to 90 mass%.

[0058] The starting material for the solid electrolyte used in the cathode is not particularly limited, as long as it is a starting material applicable to the all-solid-state lithium-ion secondary battery. As the starting material for the solid electrolyte used in the anode, it is preferable to use an oxide-based non-crystalline solid electrolyte, a sulfide-based non-crystalline solid electrolyte, a crystalline oxide, a crystalline nitride, or the like, all of which have high Li-ion conductivity.

[0059] The same materials as those used in the anode can be used as the starting material for the electrically conductive material and the starting material for the binder. 1-3. Solid electrolyte layer

[0060] The solid electrolyte layer is not particularly limited, as long as it is a solid electrolyte layer that functions as the solid electrolyte of the all-solid-state lithium-ion secondary battery. Generally, the solid electrolyte layer contains a solid electrolyte raw material. If necessary, it contains other components such as a binder.

[0061] The same materials as those used in the cathode can be used as the starting material for the solid electrolyte and the starting material for the binder.

[0062] The percentage of the solid electrolyte raw material in the solid electrolyte layer is not particularly limited. For example, it can be 50 mass% or more, in a range of 70 mass% to 99.99 mass%, or in a range of 90 mass% to 99.9 mass%. 2. Method for manufacturing the solid-state lithium-ion secondary battery

[0063] The method for manufacturing the all-solid-state lithium-ion secondary battery according to the disclosed embodiments is not particularly limited, as long as it is a method by which the all-solid-state lithium-ion secondary battery of the disclosed embodiments can be manufactured. For example, the all-solid-state lithium-ion secondary battery of the disclosed embodiments can be obtained by manufacturing a battery element including a cathode mixture, a solid electrolyte material part, and an anode mixture including an anode active material, an electrically conductive material, and a solid electrolyte, and passing electric current through the battery element.

[0064] The method for conducting electric current through the battery element is not particularly limited. In order to efficiently promote the electrochemical alloying reaction as shown by formula (1), the current density can be in a range of 0.1 mA / cm 2 up to 6.0 mA / cm 2 or the voltage can be in a range of 4.3 V to 4.7 V (vs. Li / Li + ) be.

[0065] Examples of the manufacturing method of the anode mixture, the manufacturing method of the cathode mixture, the manufacturing method of the solid electrolyte material part, and the manufacturing method of the battery element are described below in this order. 2-1. Anode mixture

[0066] The anode mixture contains an anode active material, an electrically conductive material, and a solid electrolyte. The anode mixture is not particularly limited as long as it is an anode mixture which comprises, as the anode active material, at least one active material selected from the group consisting of a metal capable of forming an alloy with Li and an oxide of the metal, and which comprises, as the solid electrolyte, particles having a BET specific surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g contains.

[0067] As described above, the anode can be obtained from the anode mixture by passing electric current through the battery element.

[0068] If necessary, the anode mixture may contain other components, such as a binder, in addition to the anode active material, the electrically conductive material and the solid electrolyte.

[0069] This is because by using the particles with a specific BET surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g as the starting material for the solid electrolyte, the electrically conductive material can be kept in a uniformly dispersed state in the anode mixture and in the anode made from the anode mixture.

[0070] In the case where the specific BET surface area of ​​the solid electrolyte particles in the anode is in a range of 1.8 m 2 / g up to 19.7 m 2 / g, the capacity retention rate is increased by setting the value A in a range of 12.4 to 56.7. However, from a manufacturing perspective, if the value A is too small, the solid electrolyte particles will aggregate. Therefore, the value A is preferably from 17.5 to 22.0 (from 17.5 to 56.7).

[0071] As the starting material for the components such as the anode active material comprising at least one selected from the group consisting of a metal capable of forming an alloy with Li and an oxide of the metal, the electrically conductive material, the solid electrolyte, and the binder, which is a component used as needed, the same starting materials as those exemplified above in “1-1. Anode” can be used.

[0072] The raw material for producing the anode mixture, that is, the raw material for the anode mixture, may contain components other than the raw materials for the anode active material, the electrically conductive material, the solid electrolyte, and the binder, which may be used as needed. Furthermore, the raw material for the anode mixture may contain components that are removed during the anode mixture production process. Examples of components contained in the raw material for the anode mixture and removed during the anode mixture production process include, but are not limited to, a solvent and a removable binder.As the removable binder, there may be used such a binder which functions as the binder in the preparation of the anode mixture and is decomposed or evaporated and removed by sintering in the step of obtaining the anode mixture, thereby providing a binder-free anode mixture.

[0073] The method for preparing the anode mixture is not particularly limited. This is because by using the particles with a BET specific surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g as the starting material for the solid electrolyte, the electrically conductive material can be kept in a uniformly dispersed state in the anode mixture prepared thereby and the anode prepared from this anode mixture.

[0074] As the method for producing the anode mixture, examples include, but are not limited to, a method for compression molding a powder of the anode mixture raw material. In the case of compression molding the powder of the anode mixture raw material, a compression pressure of about 400 MPa to about 1000 MPa is generally applied. The compression molding can be performed using a roller. In this case, a line pressure can be set to 10 kN / cm to 100 kN / cm.

[0075] Also, the following methods can be adopted: a method in which a powder of the starting material for the anode mixture containing the removable binder is subjected to compression molding and then sintered to remove the binder, and a method in which a dispersion of the starting material for the anode mixture containing the solvent and the removable binder is applied to the solid electrolyte material member or other support, dried, formed into the anode mixture, and then sintered to remove the binder. 2-2. Cathode mixture

[0076] In the manufacturing process of the disclosed embodiments, the cathode mixture contains, for example, a Li-containing cathode active material. If necessary, it contains other starting materials such as a binder, a solid electrolyte, and an electrically conductive material.

[0077] As just described, the cathode can be obtained from the cathode mixture by passing or passing electrical current through the battery element.

[0078] As the other starting materials, such as the binder, the electrically conductive material and the solid electrolyte, the same starting materials as those exemplified under “1-2. Cathode” can be used.

[0079] The starting material for producing the cathode mixture, i.e., the starting material for the cathode mixture, may further contain components that are removed in the process of producing the cathode mixture. Examples of components contained in the starting material for the cathode mixture and removed in the process of producing the cathode mixture include, but are not limited to, the same components as the solvent that can be used in the starting material for the anode mixture and the removable binder.

[0080] As the method for preparing or forming the cathode mixture, examples include, but are not limited to, the same method as the method for preparing the anode mixture. 2-3. Solid electrolyte material part

[0081] In the manufacturing method of the disclosed embodiments, the solid electrolyte material part contains, for example, a solid electrolyte raw material. It contains other components if necessary.

[0082] As described above, by passing electric current through the battery element, the solid electrolyte layer can be obtained from the solid electrolyte material part.

[0083] As the solid electrolyte starting material, the same materials as those exemplified in “1-3. Solid Electrolyte Layer” can be used.

[0084] The percentage of the solid electrolyte raw material in the solid electrolyte material part is not particularly limited. For example, it can be 50 mass% or more, in a range of 70 mass% to 99.99 mass%, or in a range of 90 mass% to 99.9 mass%.

[0085] As the other components contained in the solid electrolyte material part, the same materials as those exemplified above in “1-3. Solid electrolyte layer” can be used.

[0086] As the method for manufacturing the solid electrolyte material part, examples include, but are not limited to, a method for compression molding a solid electrolyte material powder containing the solid electrolyte raw material and, if necessary, other components. In the case of compression molding the solid electrolyte material powder, generally, as in the case of compression molding the anode mixture powder, a compression pressure of about 400 MPa to about 1000 MPa is applied. The compression molding can be performed using a roller. In this case, a line pressure can be set to 10 kN / cm to 100 kN / cm.

[0087] As another method, a cast film forming method can be used which uses a solution or dispersion of the solid electrolyte material containing the solid electrolyte raw material and, if necessary, other components. 2-4. Battery element

[0088] In the manufacturing method of the disclosed embodiments, the battery element in the disclosed embodiments is a unit of elements having the following arrangement structure, for example: the cathode mixture, the solid electrolyte material part, and the anode mixture are arranged in this order; they may be directly connected or indirectly connected through a part made of another material; and a part made of another material may be connected via one or both of the opposite side of the cathode mixture at the position where the solid electrolyte material part is present (the outer side of the cathode mixture) and the opposite side of the anode mixture at the position where the solid electrolyte material part is present (the outer side of the anode mixture) (ie,, a cathode mixture-solid electrolyte material part-anode mixture unit).

[0089] A part made of a different material can be bonded or attached to the battery element as long as Li ions can be conducted through the solid electrolyte material part in the direction from the cathode mixture side to the anode mixture side. A coating layer such as LiNbO 3 , Li 4 Ti 5 O 12 or Li 3 PO 4 may be disposed between the cathode mixture and the solid electrolyte material portion. A current collector, an outer casing, etc., may be connected to one or both of the outer side of the cathode mixture and the outer side of the anode mixture.

[0090] The battery element is typically a unit having the following arrangement structure: the cathode mixture, the anode mixture, and the solid electrolyte material part disposed between the cathode mixture and the anode mixture are directly connected, and a part made of a different material is not connected to either the outside of the cathode mixture or the outside of the anode mixture.

[0091] The method for manufacturing the battery element is not particularly limited. For example, the battery element can be manufactured as follows: the powder of the anode mixture raw material is placed in a powder compression cylinder and deposited to a uniform thickness, forming a layer of the anode mixture raw material powder. A solid electrolyte material powder containing the solid electrolyte powder and, if necessary, other components is placed on the layer of the anode mixture raw material powder and deposited to a uniform thickness, forming a layer of the solid electrolyte material powder.A cathode mixture raw material powder containing the Li-containing cathode active material is placed on the solid electrolyte material powder layer and deposited to a uniform thickness, thereby forming a cathode mixture raw material powder layer; and a thus formed powder deposit consisting of the three powder deposited layers is subjected to compression molding at once, thereby manufacturing the battery element.

[0092] The solid electrolyte material part, the anode mixture, and the cathode mixture can be formed by a method other than powder pressure molding. Details of the method are as described above. For example, the solid electrolyte material part can be formed by a cast film forming method or a coating method with a die coater using the solution or dispersion of the solid electrolyte material containing the solid electrolyte raw material.The anode mixture and the cathode mixture can be formed by the following method, for example: a method in which the dispersion containing the powder of the raw material for the anode mixture or cathode mixture and the removable binder is applied to the solid electrolyte material part or the current collector to form a coating film, and the coating film is heated to remove the binder from the coating film, or a method in which the powder containing the raw material for the anode mixture or cathode mixture and the removable binder is subjected to pressure molding to form the powder in the cathode mixture or anode mixture, and the product thereby formed is heated to remove the binder from the coating film.To increase the electrode density, the anode mixture and the cathode mixture can be subjected to compaction molding before compression molding.

[0093] The anode mixture and the cathode mixture may be formed on a support other than the solid electrolyte material part or the current collector.

[0094] In this case, the anode mixture and the cathode mixture are removed from the carrier, and the removed anode mixture or cathode mixture is applied to the solid electrolyte material part.

[0095] An example of the method for calculating the discharge capacity retention rate of the all-solid-state lithium ion secondary battery according to the disclosed embodiments will be described below.

[0096] First, the battery is charged with constant current and constant voltage until a predetermined voltage is reached. Next, the charged battery is discharged with constant current and constant voltage. The charging and discharging are defined as one cycle, and X cycles are repeated.

[0097] The discharge capacity retention rate after X cycles is calculated by the following formula (5): r=(CX / Clst)×100

[0098] In formula (5), r is the discharge capacity retention rate (%) after X cycles; C X is the discharge capacity (mAh) at the X-th cycle; and C 1st is the discharge capacity (mAh) at the first cycle. The value of X is not particularly limited; however, since the initial discharge capacity retention rate is easily affected by the uneven distribution of the electrically conductive material in the anode, X can be 10 or less, or it can be 5. Examples 1. Preparation of a solid-state lithium-ion secondary battery [Example 1] (1) Preparation of an anode mixture

[0099] Solid electrolyte particles for an anode were prepared as follows.

[0100] Under an Ar gas atmosphere, 800 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 13 kg ZrO 2 Balls (diameter: 0.3 mm), 5 kg of dehydrated heptane, and 1.5 kg of di-n-butyl ether were placed in the slurry tank of a ball mill (product name: LMZ4, manufactured by Ashizawa Finetech Ltd.). They were pulverized by wet mechanical grinding for 6 hours at a peripheral speed of 12 m / s.

[0101] After pulverization, heat treatment was carried out at 210 °C for 3 hours using a hot plate to obtain the solid electrolyte particles for the anode.

[0102] Next, 0.62 g of sulfide solid electrolyte particles, which is the thus prepared solid electrolyte raw material, 0.80 g of elemental silicon particles having an average particle diameter of 5 μm, which is an anode active material raw material, 0.03 g of VGCF, which is an electrically conductive material, and 0.32 g of a 5 mass% butyl butyrate solution of a PVdF-based resin, which is a binder, were placed in a polypropylene container. The container was subjected to ultrasonic treatment for 30 seconds in an ultrasonic disperser. Subsequently, the container was shaken for 30 minutes using a shaker, thereby preparing a raw material for the anode mixture.

[0103] The resulting anode mixture raw material was applied to a Cu foil, which serves as a current collector, using a blade method and an applicator, and dried on a hot plate at 100 °C for 30 minutes. The anode mixture on the current collector was subjected to advanced pressing to produce the anode mixture. (2) Preparation of a cathode mixture

[0104] First, 0.32 g of a Li 2 SP 2 S 5 -based, non-crystalline solid electrolyte, which has an average particle diameter of 0.8 µm and contains LiBr and LiI, which is a solid electrolyte starting material, 2.00 g LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2Particles having an average particle diameter of 6 µm, which is a cathode active material raw material, 3.0 g of a 5 mass% butyl butyrate solution of a PVdF-based resin, which is a binder, and VGCF, which is an electrically conductive material and is present in an amount of 2.5 volume% when the total volume of the solid electrolyte raw material, the cathode active material raw material, the binder, and the electrically conductive material is determined as 100 volume%, were placed in a polypropylene container. The container was subjected to ultrasonic treatment for 30 seconds in an ultrasonic disperser. Subsequently, the container was shaken for 30 minutes using a shaker, thereby preparing a cathode mixture raw material.

[0105] The thus prepared cathode mixture raw material was applied to an Al foil, which serves as a current collector, by the blade method using the applicator and dried on a hot plate at 100 °C for 30 minutes. The cathode mixture on the current collector was subjected to advanced pressing, thereby producing the cathode mixture. (3) Manufacturing a solid electrolyte material part

[0106] First, 6.0 g of a Li 2 SP 2 S 5-based non-crystalline solid electrolyte containing LiBr and LiI, which serves as a solid electrolyte raw material, and 0.05 g of a 5 mass% butyl butyrate solution of a butene rubber-based rubber, which serves as a binder, were placed in a polypropylene container. The container was subjected to ultrasonic treatment for 30 seconds in an ultrasonic disperser. Subsequently, the container was shaken for 30 minutes using a shaker, thereby preparing a paste for the solid electrolyte material part.

[0107] The resulting paste for the solid electrolyte material part was applied to an Al foil, which serves as a substrate, by the blade method using an applicator and dried on a hot plate at 100 °C for 30 minutes, thereby obtaining the solid electrolyte material part. A total of three solid electrolyte material parts were prepared in the same way. (4) Manufacture of a battery element

[0108] The anode mixture obtained in (1) above and the solid electrolyte material member prepared in (3) above were stacked in contact with each other. A pressure of 5 kN / cm was applied to the obtained current collector-anode mixture-solid electrolyte material member-aluminum foil laminate for compaction using a roller with a roll gap of 100 μm and a feed rate of 0.5 m / min. The aluminum foil used as the substrate of the solid electrolyte material member was peeled off, thereby obtaining a current collector-anode mixture-solid electrolyte material member laminate.

[0109] The cathode mixture obtained in (2) above and the solid electrolyte material member obtained in (3) above were stacked in contact with each other. A pressure of 5 kN / cm was applied to the resulting current collector-cathode mixture-solid electrolyte material member-aluminum foil laminate for compaction using a roller with a roll gap of 100 μm and a feed rate of 0.5 m / min. The aluminum foil used as the substrate of the solid electrolyte material member was peeled off, thereby obtaining a current collector-cathode mixture-solid electrolyte material member laminate.

[0110] Using a jig, the current collector-anode mixture-solid electrolyte material part laminate compacted as described above was cut to a diameter of 11.47 mm, and the current collector-cathode mixture-solid electrolyte material part laminate compacted as described above was cut to a diameter of 11.28 mm.

[0111] The solid electrolyte material member prepared in (3) above was further stacked on the current collector-anode mixture-solid electrolyte material member laminate cut as described above, such that their solid electrolyte material members were in contact with each other. Subsequently, the aluminum foil used as the substrate was peeled off from the solid electrolyte material member prepared in (3) above.

[0112] While the current collector-anode mixture-solid electrolyte material part laminate and the current collector-cathode mixture-solid electrolyte material part laminate were stacked such that the current collector-cathode mixture-solid electrolyte material part laminate was positioned at the center of the current collector-anode mixture-solid electrolyte material part laminate to which the solid electrolyte material part was transferred and their solid electrolyte material parts were in contact with each other, a pressure of 200 MPa was applied for one minute at 130 °C, thereby obtaining a battery element including the current collectors. (5) Manufacturing a solid-state lithium-ion secondary battery

[0113] Electric current was passed through the thus obtained constant-current-constant-voltage battery element at a 3-hour rate (1 / 3 C) until a predetermined voltage was reached (reverse current 1 / 100 C). Thus, the all-solid-state lithium-ion secondary battery of Example 1 was obtained. [Example 2]

[0114] The all-solid-state lithium ion secondary battery of Example 2 was manufactured in the same manner as Example 1, except that the solid electrolyte particles for the anode were prepared as described below.

[0115] Under an Ar gas atmosphere, 800 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 13 kg ZrO 2-spheres (diameter: 0.3 mm), 5 kg of dehydrated heptane, and 1.5 kg of di-n-butyl ether were placed in the slurry tank of a bead mill (product name: LMZ4, manufactured by Ashizawa Finetech Ltd.). They were pulverized by wet mechanical grinding for 4 hours at a peripheral speed of 12 m / s.

[0116] After pulverization, heat treatment was carried out at 210 °C for 3 hours using a warm or hot plate, thereby obtaining the solid electrolyte particles for the anode. [Example 3]

[0117] The all-solid-state lithium ion secondary battery of Example 3 was prepared in the same manner as Example 1, except that the solid electrolyte particles for the anode were prepared as described below.

[0118] Under an Ar gas atmosphere, 2 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li2 S-25P 2 S 5 ), 40 g ZrO 2 -spheres (diameter: 0.3 mm), 5 g dehydrated heptane, and 3 g di-butyl ether in a ZrO 2 -pot (capacity: 45 mL). The container was then hermetically sealed. The ZrO 2 The pot was placed in a planetary ball mill (product name: P7, manufactured by FRITSCH). They were pulverized by wet mechanical grinding for 20 hours at a plate rotation frequency of 200 rpm. After pulverization, a heat treatment was performed at 210 °C for 3 hours using a warm and hot plate, respectively, to obtain the solid electrolyte particles for the anode. [Example 4]

[0119] The all-solid-state lithium ion secondary battery of Example 4 was prepared in the same manner as Example 1, except that the solid electrolyte particles for the anode were prepared as described below.

[0120] Under an Ar gas atmosphere, 800 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 13 kg ZrO 2 Balls (diameter: 0.3 mm), 5 kg of dehydrated heptane, and 1.5 kg of di-n-butyl ether were placed in the slurry tank of a ball mill (product name: LMZ4, manufactured by Ashizawa Finetech Ltd.). They were pulverized by wet mechanical grinding for 10 minutes at a peripheral speed of 12 m / s. After pulverization, heat treatment was performed at 210 °C for 3 hours using the warm and hot plates, respectively, to obtain the solid electrolyte particles for the anode. [Example 5]

[0121] The all-solid-state lithium ion secondary battery of Example 5 was prepared in the same manner as Example 1, except that the solid electrolyte particles for the anode were prepared as described below.

[0122] Under an Ar gas atmosphere, 2 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 40 g ZrO 2 -spheres (diameter: 1.0 mm), 5 g dehydrated heptane, and 3 g di-butyl ether in a ZrO 2 -pot (capacity: 45 mL). The container was hermetically sealed. The ZrO 2The pot was placed in a planetary ball mill (product name: P7, manufactured by FRITSCH). They were pulverized by wet mechanical grinding for 5 hours at a plate rotation frequency of 200 rpm. After pulverization, heat treatment was performed at 210 °C for 3 hours using the warm and hot plates, respectively, to obtain the solid electrolyte particles for the anode. [Comparison example 1]

[0123] The all-solid-state lithium ion secondary battery of Comparative Example 1 was manufactured in the same manner as Example 1, except that the solid electrolyte particles for the anode were prepared as described below.

[0124] Under an Ar gas atmosphere, 30 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 450 g ZrO 2Balls (diameter: 0.3 mm), 200 g of dehydrated heptane, and 80 g of di-n-butyl ether were placed in the slurry tank of a bead mill (product name: LMZ4, manufactured by Ashizawa Finetech Ltd.). They were pulverized by wet mechanical grinding for 4 hours at a peripheral speed of 16 m / s. After pulverization, heat treatment was performed at 210 °C for 3 hours using the warm and hot plates, respectively, to obtain the solid electrolyte particles for the anode. [Example 6](1) Preparation of an anode mixture

[0125] Solid electrolyte particles for an anode were prepared as follows.

[0126] Under an Ar gas atmosphere, 50 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 485 g ZrO 2Balls (diameter: 0.3 mm), 265 g of dehydrated heptane, and 135 g of di-n-butyl ether were added to the slurry tank of a ball mill (product name: LMZ015, manufactured by Ashizawa Finetech Ltd.). They were pulverized by initial wet mechanical grinding for one hour at a peripheral speed of 16 m / s.

[0127] A slurry was obtained by the first wet mechanical grinding. While maintained at 40 °C, the slurry was pulverized by the second wet mechanical grinding for 3 hours at a peripheral speed of 3 m / s.

[0128] The slurry obtained by the second wet mechanical grinding was dried on a hot plate at 120 °C for 3 hours. Subsequently, a heat treatment was performed at 210 °C for 3 hours to obtain the solid electrolyte particles for the anode.

[0129] Next, 0.62 g of sulfide solid electrolyte particles, which is the thus prepared solid electrolyte raw material, 0.80 g of elemental silicon particles having an average particle diameter of 5 µm, which is an anode active material raw material, 0.32 g of a 5 mass% butyl butyrate solution of a PVdF-based resin, which is a binder, and 0.03 g of VGCF, which is an electrically conductive material, were placed in a polypropylene container.

[0130] The container was subjected to ultrasonic treatment for 30 seconds in an ultrasonic disperser. Subsequently, the container was shaken for 30 minutes using a shaker, thereby producing a starting material for the anode mixture.

[0131] The thus prepared raw material for the anode mixture was applied to a Cu foil, which serves as a current collector, by a blade method using an applicator and dried on a hot plate at 100 °C for 30 minutes. The anode mixture on the current collector was subjected to advanced pressing to produce the anode mixture. (2) Preparation of a cathode mixture

[0132] First, 0.32 g of a Li 2 SP 2 S 5 -based, non-crystalline solid electrolyte, which has an average particle diameter of 0.8 µm and contains LiI, which is a solid electrolyte starting material, 2.00 g LiN1 1 / 3 Co l / 3 Mn 1 / 3 O 2Particles having an average particle diameter of 4 µm, which is a cathode active material raw material, 0.30 g of a 5 mass% butyl butyrate solution of a PVdF-based resin, which is a binder, and VGCF, which is an electrically conductive material and is present in an amount of 2.5 volume% when the total volume of the solid electrolyte raw material, the cathode active material raw material, the binder, and the electrically conductive material is determined as 100 volume%, were placed in a polypropylene container. The container was subjected to ultrasonic treatment for 30 seconds in an ultrasonic disperser. Subsequently, the container was shaken for 3 minutes using a shaker, thereby preparing a cathode mixture raw material.

[0133] The thus prepared cathode mixture raw material was applied to an Al foil, which serves as a current collector, by the blade method using the applicator and dried on a hot plate at 100 °C for 30 minutes. The cathode mixture on the current collector was subjected to advanced pressing to produce the cathode mixture. (3) Manufacturing a solid electrolyte material part

[0134] First, 0.60 g of a Li 2 SP 2 S 5-based non-crystalline solid electrolyte containing LiI, a solid electrolyte raw material, and 0.05 g of a 5 mass% butyl butyrate solution of a butene rubber-based rubber, a binder, were placed in a polypropylene container. The container was subjected to ultrasonic treatment for 30 seconds in an ultrasonic disperser. Subsequently, the container was shaken for 30 minutes using a shaker, thereby preparing a paste for the solid electrolyte material part.

[0135] The thus prepared paste for the solid electrolyte material part was applied to the cathode mixture and the anode mixture by the blade method using the applicator and dried on the warm or hot plate at 100 °C for 30 minutes, thereby obtaining the solid electrolyte material parts. (4) Manufacture of a battery element

[0136] To the resulting current collector-anode mixture-solid electrolyte material part laminate obtained in the above (3) and the resulting current collector-cathode mixture-solid electrolyte material part laminate obtained in the above (3), a pressure of 5 kN / cm was applied for the purpose of densification using a roller with a roller gap of 100 µm and a feed rate of 0.5 m / min.

[0137] Using a jig, the current collector-anode mixture-solid electrolyte material part laminate compacted as described above was cut to a diameter of 13.00 mm, and the current collector-cathode mixture-solid electrolyte material part laminate compacted as described above was cut to a diameter of 11.28 mm.

[0138] While the current collector-anode mixture-solid electrolyte material part laminate and the current collector-cathode mixture-solid electrolyte material part laminate were stacked such that the current collector-cathode mixture-solid electrolyte material part laminate was arranged at the center of the current collector-anode mixture-solid electrolyte material part laminate and their solid electrolyte material parts were in contact with each other, a pressure of 200 MPa was applied for one minute at 130 °C, thereby obtaining a battery element including the current collector. (5) Manufacturing a solid-state lithium-ion secondary battery

[0139] Electric current was passed through the thus obtained constant-current-constant-voltage battery element at a 3-hour rate (1 / 3 C) until a predetermined voltage was reached (reverse current 1 / 100 C). Thus, the all-solid-state lithium-ion secondary battery of Example 6 was obtained. [Example 7]

[0140] The all-solid-state lithium ion secondary battery of Example 7 was prepared in the same manner as Example 6, except that the solid electrolyte particles for the anode were prepared as described below.

[0141] Under an Ar gas atmosphere, 50 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 485 g ZrO 2Balls (diameter: 0.3 mm), 265 g of dehydrated heptane, and 135 g of di-n-butyl ether were added to the slurry tank of a ball mill (product name: LMZ015, manufactured by Ashizawa Finetech Ltd.). They were pulverized by initial wet mechanical grinding for one hour at a peripheral speed of 16 m / s.

[0142] A slurry was obtained by the first wet mechanical grinding. While kept at 50 °C, the slurry was pulverized by the second wet mechanical grinding for 2 hours at a peripheral speed of 3 m / s.

[0143] The slurry obtained by the second wet mechanical grinding was dried on a hot plate at 120 °C for 3 hours. Subsequently, a heat treatment was performed at 210 °C for 3 hours to obtain the solid electrolyte particles for the anode. [Example 8]

[0144] The all-solid-state lithium ion secondary battery of Example 8 was prepared in the same manner as Example 6, except that the solid electrolyte particles for the anode were prepared as described below.

[0145] Under an Ar gas atmosphere, 50 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 485 g ZrO 2 Balls (diameter: 0.3 mm), 265 g of dehydrated heptane, and 135 g of di-n-butyl ether were added to the slurry tank of a ball mill (product name: LMZ015, manufactured by Ashizawa Finetech Ltd.). They were pulverized by first wet mechanical grinding for 2 hours at a peripheral speed of 16 m / s.

[0146] A slurry was obtained by the first wet mechanical grinding. While maintained at 50 °C, the slurry was pulverized by the second wet mechanical grinding for 3 hours at a peripheral speed of 3 m / s.

[0147] The slurry obtained by the second wet mechanical grinding was dried on a hot plate at 120 °C for 3 hours. Subsequently, a heat treatment was performed at 210 °C for 3 hours to obtain the solid electrolyte particles for the anode. [Example 9]

[0148] The all-solid-state lithium ion secondary battery of Example 9 was prepared in the same manner as Example 6, except that the solid electrolyte particles for the anode were prepared as described below.

[0149] Under an Ar gas atmosphere, 50 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 485 g ZrO 2 Balls (diameter: 0.3 mm), 265 g of dehydrated heptane, and 135 g of di-n-butyl ether were added to the slurry tank of a ball mill (product name: LMZ015, manufactured by Ashizawa Finetech Ltd.). They were pulverized by wet mechanical grinding for 4 hours at a peripheral speed of 16 m / s.

[0150] A slurry was obtained by the first wet mechanical grinding. While maintained at 50 °C, the slurry was pulverized by the second wet mechanical grinding for 4 hours at a peripheral speed of 3 m / s.

[0151] The slurry obtained by the second wet mechanical grinding was dried on a hot plate at 120 °C for 3 hours. Subsequently, a heat treatment was performed at 210 °C for 3 hours to obtain the solid electrolyte particles for the anode. [Example 10]

[0152] The all-solid-state lithium ion secondary battery of Example 10 was prepared in the same manner as Example 6, except that the solid electrolyte particles for the anode were prepared as described below.

[0153] Under an Ar gas atmosphere, 75 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 75 g ZrO 2 -spheres (diameter: 0.3 mm), 120 g dehydrated heptane, and 80 g di-n-butyl ether in a ZrO 2-pot (capacity: 500 mL). The container was then hermetically sealed. The ZrO 2 The pot was placed in a planetary ball mill (product name: P5, manufactured by FRITSCH). They were pulverized by wet mechanical grinding for 10 hours at a plate rotation frequency of 150 rpm (peripheral speed: 1.7 m / s). After pulverization, the resulting product was dried on a warm or hot plate at 120 °C for 3 hours. Subsequently, a heat treatment was carried out at 210 °C for 3 hours to obtain the solid electrolyte particles for the anode. [Comparison example 2]

[0154] The all-solid-state lithium ion secondary battery of Comparative Example 2 was manufactured in the same manner as Example 6, except that the solid electrolyte particles for the anode were prepared as described below.

[0155] Under an Ar gas atmosphere, 50 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 485 g ZrO 2 Balls (diameter: 0.3 mm), 265 g of dehydrated heptane, and 135 g of di-n-butyl ether were added to the slurry tank of a ball mill (product name: LMZ015, manufactured by Ashizawa Finetech Ltd.). They were pulverized by wet mechanical grinding for 4 hours at a peripheral speed of 16 m / s.

[0156] The resulting slurry was dried on a hot plate at 120 °C for 3 hours. Subsequently, a heat treatment was carried out at 210 °C for 3 hours to obtain the solid electrolyte particles for the anode. [Comparison example 3]

[0157] The all-solid-state lithium ion secondary battery of Comparative Example 3 was manufactured in the same manner as Example 6, except that the solid electrolyte particles for the anode were prepared as described below.

[0158] Under the Ar gas atmosphere, 50 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 485 g ZrO 2 Balls (diameter: 0.3 mm), 265 g of dehydrated heptane, and 135 g of di-n-butyl ether were added to the slurry tank of a ball mill (product name: LMZ015, manufactured by Ashizawa Finetech Ltd.). They were pulverized by initial wet mechanical grinding for one hour at a peripheral speed of 16 m / s.

[0159] A slurry was obtained by the first wet mechanical grinding. While kept at 50 °C, the slurry was pulverized by the second wet mechanical grinding for 3 hours at a peripheral speed of 5 m / s.

[0160] The slurry obtained by the second wet mechanical grinding was dried on a hot plate at 120 °C for 3 hours. Subsequently, a heat treatment was performed at 210 °C for 3 hours to obtain the solid electrolyte particles for the anode. [Comparison example 4]

[0161] The all-solid-state lithium ion secondary battery of Comparative Example 4 was manufactured in the same manner as Example 6, except that the solid electrolyte particles for the anode were prepared as described below.

[0162] Under an Ar gas atmosphere, 50 g of coarse particles of the sulfide solid electrolyte, represented by the composition of 15LiBr-10LiI-75(75Li 2 S-25P 2 S 5 ), 485 g ZrO 2 Balls (diameter: 0.3 mm), 265 g of dehydrated heptane, and 135 g of di-n-butyl ether were added to the slurry tank of a ball mill (product name: LMZ015, manufactured by Ashizawa Finetech Ltd.). They were pulverized by initial wet mechanical grinding for one hour at a peripheral speed of 16 m / s.

[0163] A slurry was obtained by the first wet mechanical grinding. While kept at 50 °C, the slurry was pulverized by the second wet mechanical grinding for 3 hours at a peripheral speed of 7 m / s.

[0164] The slurry obtained by the second wet mechanical grinding was dried on a hot plate at 120 °C for 3 hours. Subsequently, a heat treatment was performed at 210 °C for 3 hours to obtain the solid electrolyte particles for the anode. 2. Evaluation

[0165] (1) Measurement of BET specific surface area, mean diameter, secondary particle diameter after pulverization, and density of the solid electrolyte for the anode.

[0166] The specific BET surface area (m 2 / g) of the solid electrolyte for the anode was measured using a specific surface area measuring machine (product name: NOVA E2000, manufactured by: Quantachrome Instruments Japan GK).

[0167] The mean diameter D50 (µm) of the solid electrolyte for the anode was measured using a dynamic light scattering (DLS) particle size distribution measuring machine (product name: NANOTRAC WAVE, manufactured by: MicrotracBEL Corp.).

[0168] The secondary particle diameter of the solid anode electrolyte after pulverization was obtained as follows. First, 250 g of the above-obtained solid anode electrolyte and 350 g of butyl butyrate were mixed to obtain a mixture. The mixture was subjected to ultrasonic treatment for 1 second in an ultrasonic disperser (product name: UNTRASONIC PROCESSOR UIP500HD, manufactured by Hielscher) to obtain a paste. The secondary particle diameter of the solid anode electrolyte contained in the paste was measured using a particle size meter (product name: GRAIN GAUGE, manufactured by Dai-Ichi Sokuhan Works Co.).

[0169] The density (g / cm 3 ) of the solid electrolyte for the anode was measured by a specific gravity measuring machine (product name: AUW120D SMK-401, manufactured by: Shimadzu Corporation). (2) Evaluation of the cycle or cycle properties

[0170] The solid-state lithium-ion secondary batteries of Examples 1 to 10 and Comparative Examples 1 to 4 were discharged with constant current-constant voltage.

[0171] First, the thus-obtained all-solid-state lithium-ion secondary batteries of Examples 1 to 10 and Comparative Examples 1 to 4 were each discharged (reverse current and leakage current, respectively, 1 / 100 C). After discharge, each battery was charged with constant current / constant voltage at a 3-hour rate (1 / 3 C) until a predetermined voltage was reached, and then discharged with constant current / constant voltage. A discharge capacity at the first cycle was measured.

[0172] Under the same condition, the charge-discharge cycle was repeated five times (total 5 cycles), and a discharge capacity at the fifth cycle was measured.

[0173] A capacity retention rate was calculated at the fifth cycle by dividing the discharge capacity at the fifth cycle by the discharge capacity at the first cycle. 3. Results

[0174] Table 1 shows the measurement results of the BET specific surface area and the average diameter of the solid electrolyte for the anode, the value A obtained by the formula (1) using these values, and the specific capacity retention rate at the fifth cycle when the capacity retention rate at the fifth cycle of the all-solid-state lithium ion secondary battery of Comparative Example 1 is determined to be 100%.

[0175] Table 2 shows the measurement results of the BET specific surface area and the average diameter of the solid electrolyte for the anode, the value A obtained by the formula (1) using these values ​​and the secondary particle diameter after pulverization, and the specific capacity retention rate at the fifth cycle when the capacity retention rate at the fifth cycle of the all-solid-state lithium ion secondary battery of Comparative Example 2 is determined to be 100%. Table 1 BET specific surface area (m 2 / G) Particle diameter D50 (µm) Value A Specific capacity storage rate (%) at the 5th cycle Example 1 19,7 1,3 56,7 108 Example 2 13,4 1,6 46,7 109 Example 3 6,6 1,0 14,3 109 Example 4 5,7 2,0 24,7 109 Example 5 1,8 3,3 13,1 109 Comparison example 1 28,4 1,0 61,8 100 Table 2 BET specific surface area (m 2 / G) Particle diameter D50 (µm) Value A Secondary particle diameter after pulverization Specific capacity storage rate (%) at the 5th cycle Example 6 12 0,83 22,0 31 108 Example 7 10 0,80 17,5 31 108 Example 8 11 0,82 19,7 31 108 Example 9 11 0,91 21,3 31 108 Example 10 7 0,80 12,4 50 108 Comparison example 2 28 0,70 43,6 30 100 Comparison example 3 22 1,05 51,3 30 100 Comparison example 4 24 1,27 67,7 30 100

[0176] As shown in Table 1, when the capacity retention rate at the fifth cycle of the battery of Comparative Example 1, wherein the BET specific surface area of ​​the solid electrolyte for the anode is 28.4 m 2 / g, determined as 100%, is the specific capacity retention rate at the fifth cycle of the batteries of Examples 1 to 5, wherein the specific surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g, from 108% to 109% and high.

[0177] If the specific BET surface area is greater than 19.7 m 2 / g, the electrically conductive material is likely to adhere to the solid electrolyte particles, and an area where the density of the electrically conductive material is low appears in the anode. Therefore, it is believed that this is because, in a process during which the volume of the entire anode expands / contracts due to charging / discharging, an electron conduction path is gradually cut off in the area where the density of the electrically conductive material is low.

[0178] The specific capacity retention rates at the fifth cycle of the batteries of Examples 1 to 5, where the value A (the value indicates the shape of the solid electrolyte for the anode) is from 13.1 to 56.7, are higher than the battery of Comparative Example, where the value A is 61.8. As the value A approaches 6.0, the shape approaches a perfect spherical shape. Therefore, it is assumed that a higher cycle retention rate is obtained as the shape of the solid electrolyte particles approaches a perfect spherical shape.

[0179] As shown in Table 2, when the capacity retention rate at the fifth cycle of the battery of Comparative Example 2, wherein the BET specific surface area of ​​the solid electrolyte for the anode is 28 m 2 / g, determined as 100%, is the specific capacity retention rate at the fifth cycle of the batteries of Examples 6 to 10, wherein the BET specific surface area of ​​7 m 2 / g up to 12 m2 / g is 108% and high.

[0180] The batteries shown in Table 2 differ from the batteries shown in Table 1 in terms of manufacturing methods, materials, etc. However, regarding the relationship between the BET specific surface area and the cycle maintenance rate of the solid electrolyte for the anode, the batteries shown in Table 2 obtained similar results to those shown in Table 1, and the results shown in Table 2 confirm the results shown in Table 1.

[0181] Likewise, in Table 2, the specific capacity retention rate at the fifth cycle of the batteries of Examples 6 to 10, where the value A representing the shape of the solid electrolyte for the anode is from 12.4 to 22.0, is higher than that of the batteries of Comparative Examples 2 to 4, where the value A is from 43.6 to 67.7. Regarding this point, the results shown in Table 2 also confirm the results shown in Table 1.

[0182] For the solid electrolyte particles for the anode of Example 10, where the value of A is 12.4, the secondary particle diameter after pulverization is 50 μm, which is larger than Examples 6 to 9, where the value of A is from 17.5 to 22.0. It is believed that the secondary particle diameter after pulverization relates to the dispersibility of the solid electrolyte particles for the anode. Accordingly, from the viewpoint that the particle dispersing energy can be reduced in the preparation of the solid electrolyte particles for the anode, it is believed that it is preferable to use the solid electrolyte particles for the anode where the value of A is from 17.5 to 22.0.

[0183] From the above results, it is apparent that the all-solid-state lithium-ion secondary battery, wherein the anode contains an anode active material, an electrically conductive material, and a solid electrolyte; wherein the anode active material comprises at least one active material selected from the group consisting of a metal capable of forming an alloy with Li, an oxide of the metal, and an alloy of the metal and Li; and wherein the solid electrolyte comprises particles having a BET specific surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g and has excellent cycling properties. List of reference symbols 1 solid electrolyte layer 2 Cathode 3 Anode 101 Cathode-solid electrolyte layer-anode unit

Claims

[1] Solid-state lithium-ion secondary battery, wherein an anode comprises an anode active material, an electrically conductive material, and comprises a solid electrolyte; wherein the anode active material comprises at least one active material selected from the group consisting of a metal capable of forming an alloy with Li, an oxide of the metal, and an alloy of the metal and Li; and where the solid electrolyte comprises particles with a specific BET surface area of ​​1.8 m 2 / g up to 19.7 m 2 / g, wherein an A value for the solid electrolyte particles obtained by the following formula (1) is in a range of 12.4 to 56.7: A=specific BET surface area (m2 / g) × average diameter D50 (μm) × density (g / cm3) [2] The all-solid-state lithium-ion secondary battery according to claim 1, wherein the anode active material contains at least one active material selected from the group consisting of elemental silicon and an alloy of Si and Li. [3] The all-solid-state lithium-ion secondary battery according to claim 1 or claim 2, wherein the solid electrolyte is a sulfide solid electrolyte. [4] The all-solid-state lithium-ion secondary battery according to any one of claims 1 to 3, wherein the electrically conductive material is at least one carbonaceous material selected from the group consisting of carbon black, carbon nanotubes, and carbon fiber.

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