Electrode mixture, battery and battery system

Abstract

To provide an electrode mixture capable of forming an electrode having good cycle characteristics.SOLUTION: In the present disclosure, an electrode mixture contains an electrode active material, a conductive material and a solid electrolyte. In a case where a ratio of the electrode active material to the total of the electrode active material, the conductive material and the solid electrolyte is A1 (wt.%), a ratio of the conductive material to the total is B1 (wt.%), a ratio of the solid electrolyte to the total is C1 (wt.%), a specific surface area of the electrode active material is A2 (m2 / g), a specific surface area of the conductive material is B2 (m2 / g), a specific surface area of the solid electrolyte is C2 (m2 / g), and P=(A1×A2+B1×B2+C1×C2) / 100, the P is 5 or more and 230 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electrode mixture, a battery, and a battery system. [Background technology]

[0002] In recent years, the development of batteries has been actively pursued. For example, in the automotive industry, development of batteries for use in electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), or hybrid electric vehicles (HEVs) is underway. Batteries use electrolytes that are responsible for ion conduction, and solid electrolytes are known as such electrolytes. For example, Patent Document 1 discloses an all-solid-state lithium-ion secondary battery that includes a negative electrode containing negative electrode active material particles, a conductive material, and a solid electrolyte. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-016517 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to improve battery performance, an electrode having good cycle characteristics is required. The present disclosure has been made in view of the above-mentioned circumstances, and a main object of the present disclosure is to provide an electrode mixture capable of forming an electrode having good cycle characteristics. [Means for solving the problem]

[0005] [1] An electrode mixture containing an electrode active material, a conductive material, and a solid electrolyte, The ratio of the electrode active material to the total of the electrode active material, the conductive material, and the solid electrolyte is A1 (wt %), the ratio of the conductive material to the total is B1 (wt %), the ratio of the solid electrolyte to the total is C1 (wt %), and the specific surface area of ​​the electrode active material is A2 (m2 / g), and the specific surface area of ​​the conductive material is B2 (m 2 / g), and the specific surface area of ​​the solid electrolyte is C2 (m 2 / g) and P=(A1×A2+B1×B2+C1×C2) / 100, the P is 5 or more and 230 or less.

[0006] [2] The electrode mixture according to [1], wherein the electrode active material is a Si-based active material, the conductive material is a carbon-based conductive material, and the solid electrolyte is a sulfide solid electrolyte.

[0007] [3] A battery having a positive electrode layer, a negative electrode layer, and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer, A battery in which the positive electrode layer or the negative electrode layer contains the electrode mixture according to [1] or [2].

[0008] [4] A battery system comprising: the battery according to [3]; a temperature measuring device that measures the temperature of the battery; and a control device that controls charging and discharging of the battery based on temperature information obtained from the temperature measuring device.

[0009] [5] If the temperature of the battery is T (℃) and Q=P×T / 25, then The battery system according to [4], wherein the control device limits at least one of charging and discharging of the battery when Q is 250 or greater. [Effects of the Invention]

[0010] The electrode mixture of the present disclosure has the effect of being able to form an electrode having good cycle characteristics. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a battery according to the present disclosure. [Figure 2]FIG. 1 is an explanatory diagram illustrating a battery system according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] The electrode mixture, battery, and battery system according to the present disclosure will be described in detail below.

[0013] A. Electrode composite material The electrode mixture in the present disclosure is an electrode mixture containing an electrode active material, a conductive material, and a solid electrolyte, wherein the ratio of the electrode active material to the total of the electrode active material, the conductive material, and the solid electrolyte is A1 (wt %), the ratio of the conductive material to the total is B1 (wt %), the ratio of the solid electrolyte to the total is C1 (wt %), and the specific surface area of ​​the electrode active material is A2 (m 2 / g), and the specific surface area of ​​the conductive material is B2 (m 2 / g), and the specific surface area of ​​the solid electrolyte is C2 (m 2 / g) and P=(A1×A2+B1×B2+C1×C2) / 100, the above P is 5 or more and 230 or less.

[0014] According to the present disclosure, when the P falls within a predetermined range, an electrode mixture capable of forming an electrode with good cycle characteristics is obtained. Here, electrodes with good cycle characteristics are required to improve battery performance. Generally, the larger the specific surface area of ​​each material contained in the electrode mixture, the more contact points between the materials are expected to increase, reducing resistance and improving cycle characteristics. In response to this, the inventors did not focus solely on the specific surface area of ​​each material contained in the electrode mixture, but instead evaluated the specific surface area of ​​each material, along with the proportion of each material, for the electrode mixture as a whole. Specifically, they set P, which evaluated the contribution of the specific surface area of ​​each material to the electrode mixture as a whole, and evaluated the cycle characteristics. Surprisingly, they found that if P is too large, the cycle characteristics actually deteriorate. Therefore, they discovered that by setting P within a predetermined range, an electrode mixture capable of forming an electrode with good cycle characteristics can be obtained.

[0015] In the present disclosure, the ratio of the electrode active material to the total of the electrode active material, conductive material, and solid electrolyte is defined as A1 (wt%), the ratio of the conductive material to the total is defined as B1 (wt%), and the ratio of the solid electrolyte to the total is defined as C1 (wt%). The specific surface area of ​​the electrode active material is defined as A2 (m 2 / g), and the specific surface area of ​​the conductive material is B2 (m 2 / g), and the specific surface area of ​​the solid electrolyte is C2 (m 2 / g). Also, P = (A1 x A2 + B1 x B2 + C1 x C2) / 100. This corresponds to an index that evaluates the contribution of the specific surface area of ​​each material to the electrode mixture as a whole.

[0016] In the present disclosure, P is typically 5 or greater and 230 or less. P may be 10 or greater, or 12 or greater. On the other hand, P may be 150 or less, 100 or less, 75 or less, or 50 or less.

[0017] A1 is not particularly limited, but may be, for example, 25% by weight or more, 30% by weight or more, 35% by weight or more, or 40% by weight or more. If A1 is too small, i.e., if the proportion of the electrode active material is too low, sufficient capacity characteristics may not be obtained. On the other hand, A1 is, for example, 75% by weight or less, 70% by weight or less, or 65% by weight or less. If A1 is too large, i.e., if the proportion of the electrode active material is too high, the proportions of the conductive material and solid electrolyte may be relatively reduced, which may hinder sufficient electronic conduction and sufficient ionic conduction.

[0018] B1 is not particularly limited, but is, for example, 0.1 wt % or more, or may be 0.3 wt % or more, or may be 0.5 wt % or more. If B1 is too small, i.e., if the proportion of the conductive material is too low, sufficient electron conduction may be hindered. On the other hand, B1 is, for example, 12 wt % or less, or may be 5 wt % or less, 3 wt % or less, or may be 1 wt % or less. If B1 is too large, i.e., if the proportion of the conductive material is too high, the proportion of the electrode active material may be relatively reduced, and sufficient capacity characteristics may not be obtained.

[0019] C1 is not particularly limited, but may be, for example, 25% by weight or more, 30% by weight or more, 35% by weight or more, or 40% by weight or more. If C1 is too small, i.e., if the proportion of solid electrolyte is too low, sufficient ion conduction may be inhibited. On the other hand, C1 is, for example, 75% by weight or less, 70% by weight or less, or 65% by weight or less. If C1 is too large, i.e., if the proportion of solid electrolyte is too high, the proportion of electrode active material may be relatively reduced, and sufficient capacity characteristics may not be obtained.

[0020] A2 is not particularly limited, but may be, for example, 1 m 2 / g or more, and 2m 2 / g or more, and 2 / g or more, and 2 / g or more, and 2 On the other hand, A2 may be, for example, 500m 2 / g or less, and 400m 2 / g or less, and 2 / g or less, and 2 / g or less, and 2 / g or less, and 2 / g or less, and 2 / g or less, and 2 / g or less.

[0021] B2 is not particularly limited, but may be, for example, 5 m 2 / g or more, and 10m 2 / g or more, and 2 / g or more, and 2 / g or more, and 2 / g or more, and 2 / g or more, and 2 On the other hand, the upper limit of B2 may be, for example, 2600 m 2 / g or less.

[0022] C2 is not particularly limited, but may be, for example, 5 m 2 / g or more, and 7m 2 / g or more, and 2 / g or more, 2 On the other hand, C2 may be, for example, 150m 2 / g or less, and 120m 2 / g or less, and 2 / g or less, and 2 / g or less, and 2 / g or less.

[0023] 1. Electrode active material The electrode mixture contains an electrode active material. The electrode active material may be a negative electrode active material or a positive electrode active material. That is, the electrode mixture may be a negative electrode mixture or a positive electrode mixture.

[0024] Examples of electrode active materials include Si-based active materials such as Si, Si alloys, and SiO, carbon active materials such as graphite, Li-based active materials such as Li alloys, and Li4Ti5O 12 These active materials are useful, for example, as negative electrode active materials. Among them, Si-based active materials are particularly useful because they can increase the capacity of batteries.

[0025] The Si-based active material is an active material whose main component is Si. The Si-based active material may have a diamond-type crystalline phase, a clathrate I crystalline phase, or a clathrate II crystalline phase. In the clathrate I or II crystalline phase, a polyhedron (cage) containing pentagons or hexagons is formed by multiple Si elements. This polyhedron has spaces inside that can encapsulate metal ions such as Li ions, and therefore can suppress volume changes due to charge and discharge. In particular, it is preferable that the Si-based active material have a clathrate II crystalline phase as the main phase.

[0026] The Si-based active material may have voids inside the primary particles. The void ratio of the voids is, for example, 4% or more and 40% or less. The void ratio can be calculated by observing the cross section of the Si-based active material with a scanning electron microscope (SEM) to obtain a photograph of the particles, using image analysis software to clearly distinguish and binarize the silicon portion and the void portion from the obtained photograph, determining the areas of the silicon portion and the void portion, and then calculating the ratio of the void portion to the total.

[0027] Other examples of electrode active materials include oxide active materials. Oxide active materials are useful, for example, as positive electrode active materials. Examples of oxide active materials include LiCoO2, LiMnO2, LiNiO2, LiVO2, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc., rock salt layered active materials, LiMn2O4, Li4Ti5O 12 , Li(Ni 0.5 Mn 1.5 )O4, and olivine type active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0028] A coating layer containing a Li-ion conductive oxide may be formed on the surface of the oxide active material. This is because it can suppress the reaction between the oxide active material and the solid electrolyte (especially the sulfide solid electrolyte). An example of the Li-ion conductive oxide is LiNbO3. The thickness of the coating layer is, for example, 1 nm or more and 30 nm or less.

[0029] Average particle size of the electrode active material (D 50 ) is not particularly limited, but is, for example, 0.1 μm or more and 50 μm or less, or may be 0.5 μm or more and 30 μm or less, or may be 1 μm or more and 20 μm or less. 50 ) refers to the cumulative 50% particle size in the volume-based particle size distribution measured by a laser diffraction particle size analyzer.

[0030] 2.Conductive materials The electrode mixture contains a conductive material. Examples of the conductive material include carbon-based conductive materials and metal-based conductive materials. Examples of the carbon-based conductive material include particulate carbon-based conductive materials such as acetylene black (AB) and ketjen black (KB), and fibrous carbon-based conductive materials such as carbon fiber, carbon nanotube (CNT), and carbon nanofiber (CNF).

[0031] The diameter of the fibrous carbon-based conductive material is not particularly limited, but may be, for example, 0.1 nm to 200 nm, 0.2 nm to 100 nm, or 0.3 nm to 50 nm. On the other hand, the length of the fibrous carbon-based conductive material is not particularly limited, but may be, for example, 0.5 μm to 100 μm, or 1 μm to 50 μm. The aspect ratio (length / diameter) of the fibrous carbon-based conductive material is not particularly limited, but may be, for example, 100 to 5000, or 500 to 4000.

[0032] The fibrous carbonaceous conductive material is preferably a carbon nanotube (CNT) such as a single-walled carbon nanotube (SWCNT) or a multi-walled carbon nanotube (MWCNT). The theoretical value of the specific surface area of ​​a SWCNT is about 2600 m. 2 / g.

[0033] In addition, if the conductive material is particulate, the average particle size (D 50 ) is not particularly limited, but is, for example, 10 nm or more and 10 μm or less, or may be 20 nm or more and 1 μm or less, or may be 30 nm or more and 500 nm or less.

[0034] 3.Solid electrolyte The electrode mixture contains a solid electrolyte, such as an inorganic solid electrolyte, a sulfide solid electrolyte, an oxide solid electrolyte, a nitride solid electrolyte, or a halide solid electrolyte.

[0035] A sulfide solid electrolyte is a solid electrolyte containing sulfur as the main anion element. Examples of sulfide solid electrolytes include solid electrolytes containing Li, X (X is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In), and S. The sulfide solid electrolyte may further contain at least one of O and a halogen element. Examples of halogen elements include F, Cl, Br, and I.

[0036] The sulfide solid electrolyte may be glass (amorphous), glass ceramic, or crystalline. Examples of sulfide solid electrolytes include Li2S-P2S5, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-SiS2, Li2S-GeS2, and Li2S-P2S5-GeS2.

[0037] The oxide solid electrolyte is a solid electrolyte containing oxygen as the main anion element, the nitride solid electrolyte is a solid electrolyte containing nitrogen as the main anion element, and the halide solid electrolyte is a solid electrolyte containing halogen as the main anion element. Any known solid electrolyte can be used as these solid electrolytes.

[0038] Average particle size of the solid electrolyte (D 50 ) is not particularly limited, but is, for example, 0.1 μm or more and 50 μm or less, or may be 0.5 μm or more and 30 μm or less, or may be 1 μm or more and 20 μm or less.

[0039] 4. Electrode composite material The electrode mixture may further contain a binder. Examples of binders include rubber-based binders and fluoride-based binders. The electrode mixture may be a slurry containing a dispersion medium, or a powder containing no dispersion medium. The electrode mixture may be a negative electrode mixture used in the negative electrode layer of a battery, or a positive electrode mixture used in the positive electrode layer of a battery.

[0040] B.Battery FIG. 1 is a schematic cross-sectional view illustrating a battery according to the present disclosure. The battery 10 shown in FIG. 1 includes a positive electrode layer 1, a negative electrode layer 2, an electrolyte layer 3 disposed between the positive electrode layer 1 and the negative electrode layer 2, a positive electrode current collector 4 that collects current from the positive electrode layer 1, and a negative electrode current collector 5 that collects current from the negative electrode layer 2. In the present disclosure, the positive electrode layer 1 or the negative electrode layer 2 contains the electrode mixture described above in "A. Electrode mixture." In the present disclosure, the positive electrode layer 1, the negative electrode layer 2, and the electrolyte layer 3 may be referred to as power generation elements.

[0041] According to the present disclosure, by using the above-described electrode mixture, a battery having electrodes with good cycle characteristics can be obtained. As described above, the electrode mixture may be a negative electrode mixture or a positive electrode mixture.

[0042] 1. Negative electrode layer The negative electrode layer may contain the above-mentioned electrode mixture (negative electrode mixture). The electrode mixture is the same as that described above in "A. Electrode mixture." On the other hand, when the negative electrode layer contains the above-mentioned electrode mixture, any positive electrode layer can be used as the positive electrode layer. The thickness of the negative electrode layer is, for example, 0.1 μm or more and 1000 μm or less, or may be 0.1 μm or more and 500 μm or less, or may be 0.1 μm or more and 100 μm or less. In addition, as a method for forming the negative electrode layer, for example, a method of coating the electrode mixture (negative electrode mixture) on a negative electrode current collector can be mentioned.

[0043] 2. Positive electrode layer The positive electrode layer may contain the above-mentioned electrode mixture (positive electrode mixture). The electrode mixture is the same as that described above in "A. Electrode mixture." On the other hand, when the positive electrode layer contains the above-mentioned electrode mixture, any negative electrode layer can be used as the negative electrode layer. The thickness of the positive electrode layer is, for example, 0.1 μm or more and 1000 μm or less, or may be 0.1 μm or more and 500 μm or less, or may be 0.1 μm or more and 100 μm or less. In addition, as a method for forming the positive electrode layer, for example, a method of coating the electrode mixture (positive electrode mixture) on a positive electrode current collector can be mentioned.

[0044] 3. Electrolyte layer The electrolyte layer is a layer formed between the positive electrode layer and the negative electrode layer, and contains at least an electrolyte. The electrolyte may be a solid electrolyte or a liquid electrolyte (electrolytic solution).

[0045] The solid electrolyte is the same as that described above in "A. Electrode Composite." Meanwhile, the electrolyte solution preferably contains a supporting salt and a solvent. A known electrolyte solution can be used as the electrolyte solution. The thickness of the electrolyte layer is, for example, 0.1 μm or more and 1000 μm or less, or may be 0.1 μm or more and 500 μm or less, or may be 0.1 μm or more and 100 μm or less.

[0046] 4. Other configurations The battery according to the present disclosure preferably includes a positive electrode current collector that collects current from the positive electrode layer and a negative electrode current collector that collects current from the negative electrode layer. Examples of materials for the positive electrode current collector include stainless steel, aluminum, nickel, iron, titanium, and carbon. On the other hand, examples of materials for the negative electrode current collector include stainless steel, copper, nickel, and carbon.

[0047] The battery of the present disclosure may further include a restraining jig that applies a restraining pressure to the positive electrode layer, electrolyte layer, and negative electrode layer in the thickness direction. In particular, when the electrolyte layer contains a solid electrolyte, applying a restraining pressure is preferable to form good ion conduction paths and electron conduction paths. The restraining pressure is, for example, 0.1 MPa or more, or may be 1 MPa or more, or may be 5 MPa or more. Meanwhile, the restraining pressure is, for example, 100 MPa or less, or may be 50 MPa or less, or may be 20 MPa or less.

[0048] 5.Battery The type of battery in the present disclosure is not particularly limited, but is typically a lithium-ion battery. The battery in the present disclosure may be a liquid battery containing an electrolytic solution as an electrolyte layer, or a solid battery containing a solid electrolyte as an electrolyte layer. The battery in the present disclosure may be a primary battery or a secondary battery, but a secondary battery is preferred because it can be repeatedly charged and discharged and is useful, for example, as an on-board battery.

[0049] Examples of uses of the battery include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. In particular, it is preferable that the battery be used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The battery may also be used as a power source for mobile objects other than vehicles (for example, trains, ships, and aircraft), or as a power source for electrical appliances such as information processing devices. The method for manufacturing the battery is not particularly limited, and known methods can be used.

[0050] C. Battery System Fig. 2 is an explanatory diagram illustrating a battery system according to the present disclosure. The battery system 20 shown in Fig. 2 includes a battery 10, a temperature measuring device 11 that measures the temperature of the battery 10, and a control device 12 that controls charging and discharging of the battery 10 based on temperature information obtained from the temperature measuring device 11.

[0051] According to the present disclosure, by using the above-described battery, a battery system with good cycle characteristics is obtained. Furthermore, by having a control device control charge / discharge (at least one of charge and discharge) according to the temperature of the battery, a battery system with even better cycle characteristics is obtained. As described above, the inventors have discovered that if the value of P is too large, the cycle characteristics will conversely deteriorate. Furthermore, they have found that the cycle characteristics depend not only on P but also on the temperature T of the battery, and as will be described later, by controlling charge / discharge using Q, which is set based on P and T, as an index, a battery system with even better cycle characteristics is obtained.

[0052] 1.Battery Regarding batteries, the same applies as described above in "B. Batteries."

[0053] 2.Temperature measuring device The temperature measuring device is configured to measure the temperature of the battery. Preferably, the temperature measuring device is configured to measure the temperature of the power generating element of the battery. The temperature measuring device is not particularly limited, and a general temperature sensor can be used.

[0054] 3. Control device The control device is configured to control the charging and discharging of the battery based on temperature information obtained from the temperature measurement device. The control device typically includes a CPU (Central Processing Unit), memory, and input / output ports for inputting and outputting various signals. The memory includes, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), and a rewritable non-volatile memory. The CPU executes programs stored in the memory to perform various processes. The control device also has, for example, a calculation unit and a determination unit as processing blocks for realizing its functions.

[0055] The calculation unit is configured to calculate a predetermined value based on temperature information obtained from the temperature measurement device. For example, the calculation unit is preferably configured to calculate Q=P×T / 25, where T (°C) is the temperature of the battery. P is the same as described above in "B. Battery" and is pre-stored in memory.

[0056] The determination unit is configured to control charging and discharging of the battery 10 based on the value calculated by the calculation unit. For example, the determination unit may be configured to limit at least one of charging and discharging of the battery when Q becomes equal to or greater than a predetermined value. The predetermined value may be, for example, 250 or more, 200 or more, 150 or more, or 100 or more. The predetermined value may also be 10 or less, 15 or less, or 20 or less. Examples of control to limit charging and discharging include control to reduce the charging rate, control to stop charging, control to reduce the discharging rate, and control to stop discharging.

[0057] 4. Battery System The battery system of the present disclosure may include a cooling device that cools the battery. The cooling device may be configured to cool the battery based on an instruction from a control device, for example, when the battery temperature T or the above-mentioned Q becomes equal to or greater than a predetermined value. A general cooling device can be used as the cooling device. The cooling device may be configured to cool the battery when the battery temperature T becomes equal to or greater than a predetermined value (for example, 60°C). The cooling device may also be configured to cool the battery when, for example, Q becomes equal to or greater than a predetermined value (for example, 250).

[0058] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Example]

[0059] [Preparation of active material 1] A thin film was prepared using Si and Zn by RF magnetron sputtering. The obtained thin film was crushed using a mortar and pestle, and then the Zn was removed by treatment with hydrochloric acid to obtain Si (active material 1). The BET specific surface area of ​​the obtained active material 1 was measured using a fully automatic gas adsorption measurement device (autosorb-iQ) and found to be 400 m 2 / g.

[0060] [Preparation of active material 2] A thin film was prepared using Si and ZnO by RF magnetron sputtering. The obtained thin film was crushed using a mortar and pestle, and then the ZnO was removed by treatment with hydrochloric acid to obtain Si (active material 2). The BET specific surface area of ​​the obtained active material 2 was measured using the above-mentioned measuring device and found to be 400 m 2 / g.

[0061] [Preparation of active material 3] Metallic Li and Si powder were weighed out in a molar ratio of 4:1 and mixed in a mortar under an Ar atmosphere at room temperature for 0.5 hours to react. This produced Li4Si. The resulting Li4Si was then reacted with ethanol under an Ar atmosphere. The resulting reaction product is believed to contain Si and CH3CHOLi. The reaction product was filtered, and the filtered solid was dried at 120°C for at least 3 hours to produce powdered porous Si.

[0062] The obtained porous Si was used to produce a Na-Si alloy using NaH as a Na source. The NaH used was previously washed with hexane. NaH and porous Si were weighed out to a molar ratio of 1.05:1 and mixed using a cutter mill. The mixture of NaH and porous Si was heated in a heating furnace under an Ar atmosphere at 475°C for 40 hours to obtain a powdered Na-Si alloy.

[0063] Using the resulting Na-Si alloy and AlF3 as a sodium trap, silicon clathrate was produced by solid-phase synthesis. Specifically, the Na-Si alloy and AlF3 were weighed out in a molar ratio of 1:0.35 and mixed using a cutter mill to obtain the reaction raw material. The resulting powdered reaction raw material was placed in a stainless steel reaction vessel and heated in a heating furnace under an Ar atmosphere at 310°C for 60 hours to induce reaction. The resulting reaction product is believed to contain the desired active material and by-products NaF and Al. This reaction product was washed with a mixed solvent of HNO3 and HO in a volume ratio of 10:90. This removed by-products from the reaction product. After washing, the mixture was filtered, and the filtered solid was dried at 120°C for at least 3 hours to obtain a powdered active material. Five grams of the resulting material was weighed, washed in HF solution for 1 hour, filtered, and then dried at 120°C for at least 3 hours to obtain porous clathrate Si (active material 3). The BET specific surface area of ​​the obtained active material 3 was measured by the above-mentioned measuring device and found to be 60 m 2 / g.

[0064] [Preparation of active material 4] Si (SIEPB23 manufactured by Kojundo Kagaku Co., Ltd.) was prepared as active material 4. The BET specific surface area of ​​active material 4 was measured using the above-mentioned measuring device, and found to be 2 m 2 / g.

[0065] [Preparation of sulfide solid electrolyte 1] Li2S and P2S5 were mixed in a molar ratio of Li2S:P2S5 = 75:25 to obtain a raw material mixture. The pot containing the obtained raw material mixture was attached to a planetary ball mill (P7 manufactured by Fritsch) and subjected to mechanical milling at a rotation speed of 500 rpm for 20 hours to obtain a sulfide glass. The obtained sulfide glass was then molded into pellets, vacuum sealed in a quartz tube, and heat-treated in a muffle furnace at 180 °C for 2 hours. This resulted in a Li2S-P2S5-based glass ceramic (sulfide solid electrolyte 1). The BET specific surface area of ​​the obtained sulfide solid electrolyte 1 was measured using the above-mentioned measuring device and found to be 8 m 2 / g.

[0066] [Preparation of sulfide solid electrolyte 2] The sulfide solid electrolyte 1 was pulverized using a planetary ball mill (P7 manufactured by Fritsch) at 200 rpm for 3 hours to obtain the sulfide solid electrolyte 2. The BET specific surface area of ​​the obtained sulfide solid electrolyte 2 was measured using the above-mentioned measuring device and found to be 20 m 2 / g.

[0067] [Preparation of sulfide solid electrolyte 3] The sulfide solid electrolyte 1 was pulverized using a planetary ball mill (P7 manufactured by Fritsch) at 400 rpm for 3 hours to obtain the sulfide solid electrolyte 3. The BET specific surface area of ​​the obtained sulfide solid electrolyte 3 was measured using the above-mentioned measuring device and found to be 25 m 2 / g.

[0068] [Preparation of conductive materials 1 and 2] Single-walled carbon nanotubes (SWCNT, TUBALL manufactured by OCSiAl) were prepared as conductive material 1. Vapor-grown carbon fiber (VGCF, VGCF-H manufactured by Resonac) was prepared as conductive material 2. The BET specific surface areas of conductive materials 1 and 2 were measured using the above-mentioned measuring device and found to be 878 m², respectively. 2 / g, 13m 2 / g.

[0069] [Comparative Example 1] (Preparation of negative electrode) Active material 1, sulfide solid electrolyte 2, conductive material 1, a butyl butyrate solution containing 5 wt% PVDF binder, and butyl butyrate were added to a polypropylene container and stirred for 30 seconds using an ultrasonic disperser (UH-50, manufactured by SMT). The composition of the negative electrode layer was as shown in Table 1. Next, the container was shaken for 30 minutes using a shaker (TTM-1, manufactured by Shibata Scientific Co., Ltd.). Using an applicator, the solution was applied to a negative electrode current collector (Cu foil, manufactured by UACJ) using the blade method, and then dried on a hot plate at 100°C for 30 minutes. This resulted in a negative electrode having a negative electrode current collector and a negative electrode layer.

[0070] (Preparation of positive electrode) The positive electrode active material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 A butyl butyrate solution containing 5 wt% PVDF binder (O2, average particle size 6 μm), a sulfide solid electrolyte (Li2S-P2S5-based glass ceramic), a conductive material (VGCF), and butyl butyrate were added and stirred for 30 seconds using an ultrasonic disperser (UH-50, manufactured by SMT). The container was then shaken for 3 minutes using a shaker (TTM-1, manufactured by Shibata Scientific Co., Ltd.), followed by another 30 seconds of stirring using the ultrasonic disperser and another 3 minutes of shaking using the shaker. The mixture was applied to a positive electrode current collector (Al foil, manufactured by Showa Denko KK) using an applicator by the blade method and dried for 30 minutes on a hot plate at 100 °C. This resulted in a positive electrode comprising a positive electrode current collector and a positive electrode layer. The area of ​​the positive electrode was smaller than that of the negative electrode.

[0071] (Preparation of solid electrolyte layer) A sulfide solid electrolyte (Li2S-P2S5-based glass ceramic), a heptane solution containing 5 wt% butylene rubber binder, and heptane were added to a polypropylene container and stirred for 30 seconds using an ultrasonic disperser (UH-50, manufactured by SMT). The container was then shaken for 30 minutes using a shaker (TTM-1, manufactured by Shibata Scientific Co., Ltd.). The mixture was applied to a release sheet (Al foil) using an applicator by the blade method and dried on a hot plate at 100°C for 30 minutes. This resulted in a transfer member having a release sheet and a solid electrolyte layer.

[0072] (Fabrication of all-solid-state batteries) A solid electrolyte layer for bonding was placed on the positive electrode layer of the positive electrode, and the resultant was set in a roll press and pressed at 100 kN / cm and 165° C. This produced a first laminate.

[0073] Next, the negative electrode was set in a roll press and pressed at 60 kN / cm and 25°C. This resulted in a pressed negative electrode. Thereafter, a solid electrolyte layer for bonding and a transfer member were arranged in this order from the negative electrode layer side. At this time, the solid electrolyte layer for bonding and the solid electrolyte layer on the transfer member were arranged so as to face each other. The obtained laminate was set in a planar uniaxial press and temporarily pressed at 100 MPa and 25°C for 10 seconds. Then, the release sheet was peeled off from the solid electrolyte layer. This resulted in a second laminate.

[0074] Next, the bonding solid electrolyte layer of the first laminate and the solid electrolyte layer of the second laminate were arranged to face each other, and then set in a flat uniaxial press and pressed at 200 MPa and 120°C for 1 minute, thereby obtaining an all-solid-state battery.

[0075] Comparative Example 2 An all-solid-state battery was obtained in the same manner as in Comparative Example 1, except that active material 2 was used instead of active material 1 and the composition of the negative electrode layer was changed to the composition shown in Table 1.

[0076] [Examples 1 to 5] All-solid-state batteries were obtained in the same manner as in Comparative Example 1, except that active material 3 was used instead of active material 1, sulfide solid electrolyte 1 was used instead of sulfide solid electrolyte 2, and the composition of the negative electrode layer was changed to the composition shown in Table 1. In Examples 2 to 4, the compositions of the all-solid-state batteries were the same, but the test temperatures described below were different.

[0077] [Examples 6 to 8] An all-solid-state battery was obtained in the same manner as in Comparative Example 1, except that active material 3 was used instead of active material 1, sulfide solid electrolyte 3 was used instead of sulfide solid electrolyte 2, and the composition of the negative electrode layer was changed to the composition shown in Table 1.

[0078] [Example 9] An all-solid-state battery was obtained in the same manner as in Comparative Example 1, except that active material 3 was used instead of active material 1, sulfide solid electrolyte 3 was used instead of sulfide solid electrolyte 2, conductive material 2 was used instead of conductive material 1, and the composition of the negative electrode layer was changed to the composition shown in Table 1.

[0079] [Example 10] An all-solid-state battery was obtained in the same manner as in Comparative Example 1, except that active material 4 was used instead of active material 1, sulfide solid electrolyte 3 was used instead of sulfide solid electrolyte 2, and the composition of the negative electrode layer was changed to the composition shown in Table 1.

[0080] [Example 11] An all-solid-state battery was obtained in the same manner as in Comparative Example 1, except that active material 4 was used instead of active material 1, sulfide solid electrolyte 3 was used instead of sulfide solid electrolyte 2, conductive material 2 was used instead of conductive material 1, and the composition of the negative electrode layer was changed to the composition shown in Table 1.

[0081] [evaluation] The all-solid-state batteries obtained in Examples 1 to 11 and Comparative Examples 1 and 2 were restrained using a restraining jig and subjected to constant current / constant voltage charging at a 10-hour rate (1 / 10C) to 4.55 V at a test temperature T [°C], followed by discharging at a 1-hour rate (1C) to 3.0 V. Furthermore, constant current / constant voltage charging was performed at a 3-hour rate (1 / 3C) to 4.35 V, and constant current / constant voltage discharging was performed at a 3-hour rate (1 / 3C) to 3.00 V, and the initial discharge capacity was determined. Subsequently, the same charge / discharge cycle was repeated five times, and the discharge capacity at the fifth cycle was determined. The discharge capacity at the fifth cycle was divided by the initial discharge capacity to calculate the capacity retention rate (%). The results are shown in Table 1. The durability performance shown in Table 1 is a relative value of the capacity retention rate for Examples 1 to 11 and Comparative Example 2, with the capacity retention rate for Comparative Example 1 set to 100.

[0082] [Table 1]

[0083] As shown in Table 1, it was confirmed that good cycle characteristics were obtained when P was 230 or less. It was also confirmed that even better cycle characteristics were obtained when Q was 100 or less. [Explanation of symbols]

[0084] 1 ... positive electrode layer 2 ...Negative layer 3 ...Electrolyte layer 4 ...positive electrode current collector 5 ...Negative electrode current collector 10 …batteries

Claims

1. An electrode mixture containing an electrode active material, a conductive material, and a solid electrolyte, The ratio of the electrode active material to the total of the electrode active material, the conductive material, and the solid electrolyte is A １ (wt%), and the ratio of the conductive material to the total is B １ (wt%), and the ratio of the solid electrolyte to the total is C １ (wt%), and the specific surface area of ​​the electrode active material is A ２ (m ２ / g), and the specific surface area of ​​the conductive material is B ２ (m ２ / g), and the specific surface area of ​​the solid electrolyte is C ２ (m ２ / g), and P = (A １ ×A ２ +B １ ×B ２ +C １ ×C ２ ) / 100, the P is 5 or more and 230 or less.

2. 2. The electrode mixture according to claim 1, wherein the electrode active material is a Si-based active material, the conductive material is a carbon-based conductive material, and the solid electrolyte is a sulfide solid electrolyte.

3. A battery having a positive electrode layer, a negative electrode layer, and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer, A battery, wherein the positive electrode layer or the negative electrode layer contains the electrode mixture according to claim 1 or 2.

4. A battery system comprising: the battery according to claim 3; a temperature measuring device that measures the temperature of the battery; and a control device that controls charging and discharging of the battery based on temperature information obtained from the temperature measuring device.

5. When the temperature of the battery is T (°C) and Q = P x T / 25, The battery system according to claim 4 , wherein the control device limits at least one of charging and discharging of the battery when the Q is 250 or greater.

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