JP5660538B2 - Electrode body for all-solid-state secondary battery, all-solid-state secondary battery, method for producing all-solid-state secondary battery electrode body, method for producing all-solid-state secondary battery - Google Patents

Description

  The present invention relates to an electrode body for an all-solid-state secondary battery that can relieve stress generated between an active material layer and a current collector and has high ion conductivity.

  With the rapid spread of information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones in recent years, development of batteries that are used as power sources has been regarded as important. Also in the automobile industry and the like, development of high-power and high-capacity batteries for electric vehicles or hybrid vehicles is being promoted. Currently, among various batteries, lithium secondary batteries are attracting attention from the viewpoint of high energy density.

  Since lithium secondary batteries currently on the market use an electrolyte containing a flammable organic solvent, they are equipped with a safety device that prevents the temperature rise during short-circuiting and in terms of structure and materials for short-circuit prevention. Improvement is needed. In contrast, an all-solid lithium secondary battery in which the electrolyte solution is changed to a solid electrolyte layer to make the battery all solid does not use a flammable organic solvent in the battery, so the safety device can be simplified and manufactured. It is considered to be excellent in cost and productivity.

  As such an all-solid secondary battery, a so-called thin film battery is known. A thin film battery is a battery in which a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer are formed of a dense thin film. For example, Patent Document 1 discloses a lithium secondary battery in which at least one of a positive electrode, a solid electrolyte layer, and a negative electrode is a deposited layer made of ultrafine particles. This technique is intended to prevent destruction of the solid structure and peeling of the electrode-electrolyte layer interface due to differences in the thermal expansion coefficient and contraction rate of the electrode and the solid electrolyte layer.

  On the other hand, although not a thin-film battery, Patent Document 2 discloses a lithium ion secondary battery in which at least one of a positive electrode current collector and a negative electrode current collector includes a viscoelastic body. This technique is intended to provide a battery in which the current collector adheres well to the electrode and does not have a possibility of peeling even after the battery is manufactured.

JP 2004-213938 A JP 2009-181874 A

  Since the thin-film type active material layer is dense, the effect of expansion and contraction of the active material is likely to appear as compared to a bulk type active material layer (for example, an active material layer formed by compacting powder). Note that the expansion and contraction of the active material specifically refers to a change in the volume of the active material due to insertion and desorption of metal ions. In addition, since the thin-film active material layer is tightly bound to the current collector, stress is easily generated between the active material layer and the current collector due to expansion and contraction of the active material, and the two materials are peeled off or the active material There is a problem that the layer is easily broken. On the other hand, an electrode body for an all-solid-state secondary battery with high ion conductivity is required from the viewpoint of increasing the output and capacity of the battery.

  The present invention has been made in view of the above circumstances, and provides an electrode body for an all-solid-state secondary battery that can relieve stress generated between an active material layer and a current collector and has high ion conductivity. The main purpose.

  As a result of extensive research conducted by the present inventors to solve the above-mentioned problems, the current material that is softer than the active material layer is intentionally selected by paying attention to the relationship between the hardness of the active material layer and the current collector. As a result, it was found that the stress generated between the active material layer and the current collector can be relaxed. Furthermore, the present inventors have found that the ionic conductivity of the thin film type active material layer is greatly affected by the hardness of the current collector, and by setting the current collector hardness within a predetermined range. And the knowledge that the electrode body for all-solid-state secondary batteries with high ion conductivity was obtained was acquired. The present invention has been made based on these findings.

  That is, in the present invention, it has a current collector and a thin film type active material layer formed on the current collector, and the current collector has a Vickers hardness higher than the Vickers hardness of the active material layer. And an electrode body for an all-solid-state secondary battery characterized by being in the range of 40 to 600.

  According to the present invention, since the Vickers hardness of the current collector is lower than the Vickers hardness of the active material layer, an electrode body in which stress generated between the active material layer and the current collector is relaxed can be obtained. That is, even when the active material expands and contracts due to charge and discharge, the current collector can be deformed so as to follow the volume change of the active material layer, thereby reducing the stress between the two. Separation between the layer and the current collector, destruction of the active material layer, and the like can be suppressed.

  In the said invention, it is preferable that the said electrical power collector is Al, Al alloy, Cu, or Cu alloy.

  In the said invention, it is preferable that the said active material layer is formed by the aerosol deposition method.

  Moreover, in this invention, it has the electrode body for all-solid-state secondary batteries mentioned above, The all-solid-state secondary battery characterized by the above-mentioned is provided.

  According to the present invention, by using the electrode body for an all-solid-state secondary battery described above, an all-solid-state secondary battery that suppresses separation between the active material layer and the current collector, destruction of the active material layer, and the like is provided. Can do.

  The present invention further includes an active material layer forming step of forming a thin film type active material layer on the current collector, wherein the current collector has a Vickers hardness lower than the Vickers hardness of the active material layer. And the manufacturing method of the electrode body for all-solid-state secondary batteries characterized by being in the range of 40-600 is provided.

  According to the present invention, since the Vickers hardness of the current collector is lower than the Vickers hardness of the active material layer, it is possible to obtain an electrode body in which stress generated between the active material layer and the current collector is relaxed.

  In the said invention, it is preferable to form the said active material layer by the aerosol deposition method.

  In the said invention, it is preferable that the said electrical power collector is Al, Al alloy, Cu, or Cu alloy.

  Moreover, in this invention, the manufacturing method of the all-solid-state secondary battery characterized by using the electrode body for all-solid-state secondary batteries obtained by the manufacturing method of the electrode body for all-solid-state secondary batteries mentioned above is provided. .

  According to the present invention, by using the electrode body for an all-solid-state secondary battery described above, an all-solid-state secondary battery that suppresses separation between the active material layer and the current collector, destruction of the active material layer, and the like is obtained. Can do.

  The electrode body for an all-solid-state secondary battery according to the present invention can relieve stress generated between the active material layer and the current collector and has an effect of high ion conductivity.

It is a schematic sectional drawing which shows an example of the electrode body for all-solid-state secondary batteries of this invention. It is a schematic sectional drawing which shows the other example of the electrode body for all-solid-state secondary batteries of this invention. It is a schematic sectional drawing which shows an example of the all-solid-state secondary battery of this invention. It is a schematic sectional drawing which shows an example of the manufacturing method of the electrode body for all-solid-state secondary batteries of this invention. It is a schematic diagram explaining the aerosol deposition method. It is a schematic sectional drawing which shows an example of the manufacturing method of the all-solid-state secondary battery of this invention. It is the photograph after the charging / discharging test with respect to the battery obtained by the Example and the comparative example. It is a graph which shows the relationship between the hardness of an electrical power collector, and Li ion conductivity. It is a graph which shows the relationship between the hardness of an electrical power collector, and Li ion conductivity.

  Hereinafter, an electrode body for an all-solid secondary battery, an all-solid secondary battery, a method for producing an electrode body for an all-solid secondary battery, and a method for producing an all-solid secondary battery according to the present invention will be described in detail.

A. First, an electrode body for an all-solid-state secondary battery of the present invention (hereinafter sometimes simply referred to as an electrode body) will be described. An electrode body for an all-solid-state secondary battery of the present invention includes a current collector and a thin film type active material layer formed on the current collector, and the current collector has a Vickers hardness of the active material. It is lower than the Vickers hardness of the material layer and is in the range of 40 to 600.

  FIG. 1 is a schematic cross-sectional view showing an example of an electrode body for an all-solid secondary battery of the present invention. An electrode body 10 for an all-solid-state secondary battery shown in FIG. 1 has a current collector 1 and a thin-film active material layer 2 formed on the current collector 1. The present invention is greatly characterized in that the current collector 1 has a Vickers hardness lower than the Vickers hardness of the active material layer 2 and in the range of 40 to 600.

  According to the present invention, since the Vickers hardness of the current collector is lower than the Vickers hardness of the active material layer, an electrode body in which stress generated between the active material layer and the current collector is relaxed can be obtained. That is, even when the active material expands and contracts due to charge and discharge, the current collector can be deformed so as to follow the volume change of the active material layer, thereby reducing the stress between the two. Separation between the layer and the current collector, destruction of the active material layer, and the like can be suppressed.

In addition, according to the present invention, since the current collector has a Vickers hardness within a specific range, an electrode body having high ion conductivity can be obtained. Since the thin film type active material layer is dense, it is greatly affected by the hardness of the current collector. For example, when the active material layer is formed using the aerosol deposition method, if the current collector is too hard, the impact force at the time of collision of the raw material particles becomes excessively large, and the crystal size is reduced more than necessary. move on. As a result, it is considered that the crystal grain boundary density increases (crystallinity decreases) and ion conduction is inhibited. On the other hand, when the hardness of the current collector is too low, the crystal size of the particles contained in the film is not excessively refined, but the density of the film itself decreases. As a result, the Li ion conductivity of the film is considered to be low. In this invention, it can be set as an active material layer with high ion conductivity by making the Vickers hardness of a collector into a predetermined range. The relationship between the hardness of the current collector and the ionic conductivity of the active material layer is particularly remarkable in the aerosol deposition method, but is basically the same in other film forming methods described later.
Hereinafter, the electrode body for an all-solid-state secondary battery of the present invention will be described for each configuration.

1. First, the current collector in the present invention will be described. The current collector in the present invention has a Vickers hardness lower than that of an active material layer described later. Furthermore, the Vickers hardness of the current collector is usually in the range of 40 to 600. Here, Vickers hardness (HV) is a kind of indentation hardness, and a surface area S is calculated from the length of the diagonal line of the recess remaining after the indenter having a predetermined shape is pushed into the surface of the object to be measured and the load is removed. The load F is obtained by dividing the load F by the surface area S. The Vickers hardness in this invention can be calculated | required by the method based on JISZ2244.

  The current collector has a Vickers hardness of usually 40 or more, preferably 60 or more. This is because if the Vickers hardness of the current collector is too low, the active material layer may not be dense and sufficient ionic conductivity may not be obtained. On the other hand, the current collector generally has a Vickers hardness of 600 or less and preferably 580 or less. This is because if the Vickers hardness of the current collector is too high, the active material is excessively refined, resulting in an increase in crystal grain boundary density and insufficient ion conductivity.

  In the present invention, the current collector has a Vickers hardness lower than that of an active material layer described later. The difference between the two is preferably in the range of 1 to 600, for example, and more preferably in the range of 50 to 500. If the difference between the two is too small, it may be difficult for the current collector to follow the volume change of the active material layer. If the difference between the two is too large, the active material layer becomes excessively dense. This is because destruction easily occurs.

  The material of the current collector is not particularly limited as long as it has electronic conductivity, and examples thereof include metal materials and carbon materials. Examples of the metal material include Cu, Ni, V, Au, Pt, Al, Mg, Fe, Ti, Co, Zn, Ge, In, Li, and alloys mainly containing the above elements. Among them, Al, Al alloy, Cu, Cu alloy, and stainless steel are preferable. Further, the current collector may be one obtained by vapor-depositing the metal material or the carbon material on a substrate. Examples of the substrate include resin films such as polyamide, polyimide, PET, PPS, and polypropylene, glass plates, and silicon plates. The thickness of the current collector is not particularly limited, but is preferably in the range of 0.05 μm to 1 mm, for example, and more preferably in the range of 0.1 μm to 500 μm.

2. Active Material Layer Next, the active material layer in the present invention will be described. The active material layer in the present invention is a thin film type active material layer formed on the current collector, and has a Vickers hardness higher than that of the current collector. The active material layer is usually composed of active material particles.

The active material in the present invention is not particularly limited as long as it can occlude / release metal ions, and examples thereof include oxide active materials, sulfide active materials, and carbon active materials. Examples of the oxide active material include lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , lithium manganate (LiMn ₂ O ₄ ), Li _{1 + x} Mn _2−xy M _y O ₄ (M is one or more selected from Al, Mg, Co, Fe, Ni, Zn, 0 ≦ x + y ≦ 2) Examples thereof include lithium titanate, lithium metal phosphate (LiMPO ₄ , M is one or more selected from Fe, Mn, Co, and Ni), vanadium oxide (V ₂ O ₅ ), and molybdenum oxide (MoO ₃ ). Examples of the sulfide active material include titanium sulfide (TiS ₂ ). Examples of the carbon active material include graphite and hard carbon.

  In the present invention, examples of the active material include lithium cobalt nitride, lithium silicon oxide, lithium metal, and lithium alloy (LiM and M are at least one of Sn, Si, Al, Ge, Sb, and P). be able to. Further, MgM (M is at least one of Sn, Ge, and Sb) and NSb (N is at least one of In, Cu, and Mn) that are lithium storage intermetallic compounds may be used as the active material. . In addition, there is no clear distinction between the positive electrode active material and the negative electrode active material, and comparing the charge / discharge potentials of two types of compounds, the one showing a noble potential is used as the positive electrode, and the one showing the base potential is used as the negative electrode A battery of any voltage can be constructed.

  Further, the active material layer in the present invention is preferably composed of polycrystalline active material particles. This is because an active material layer having a low bulk resistance can be obtained. The crystal size of the active material particles is not particularly limited, but is preferably 14 nm or more, and more preferably 14.2 nm or more. This is because an active material layer having high ion conductivity can be obtained. The crystal size can be determined from the full width at half maximum (FWHM) of the XRD peak.

  The relative density of the active material layer is not particularly limited, but is preferably in the range of 80% to 99%, for example, and more preferably in the range of 85% to 95%. If the relative density of the active material layer is too high (for example, exceeding 100%), the active material layer may be distorted, which may cause a decrease in ionic conductivity due to a decrease in crystallinity. If it is too low, the active material layer will not be dense, and sufficient ion conductivity may not be obtained. The relative density of the active material layer can be obtained by dividing the actual density of the active material layer by the theoretical density of the active material layer. Note that the actual density of the active material layer can be obtained by obtaining the volume of the active material layer from the area and film thickness of the active material layer and dividing the weight of the active material layer by the volume.

The active material layer in the present invention preferably has high ionic conductivity at room temperature. This is because a high-power all-solid secondary battery can be obtained. For example, when the active material layer is made of LiCoO ₂ , the Li ion conductivity at room temperature is preferably 1 × 10 ⁻⁴ S / cm or more, for example, and preferably 2 × 10 ⁻⁴ S / cm or more. It is more preferable that it is 4 × 10 ⁻⁴ S / cm or more. The thickness of the active material layer is not particularly limited, but is preferably in the range of 0.1 μm to 1000 μm, for example, and more preferably in the range of 0.1 μm to 300 μm. In addition, the active material layer in the present invention can be formed by various film forming methods to be described later, but among them, the active material layer is preferably formed by an aerosol deposition method.

3. All-solid-state secondary battery electrode body The all-solid-state secondary battery electrode body of the present invention is characterized by having the above-described current collector and active material layer. As shown in FIG. 2, the electrode body for an all-solid-state secondary battery of the present invention may have a thin-film solid electrolyte layer 3 on the active material layer 2. By providing the thin film type solid electrolyte layer, it becomes a useful member of the thin film type battery.

As the solid electrolyte material constituting the solid electrolyte layer, for example, an inorganic material having ion conductivity can be mentioned, and specifically, Li ₂ O—B ₂ O ₃ —P ₂ O ₅ , Li ₂ O—SiO. ₂ , oxide amorphous solid electrolyte materials such as Li ₂ O—B ₂ O ₃ , Li ₂ O—B ₂ O ₃ —ZnO, Li ₂ S—SiS ₂ , LiI—Li ₂ S—SiS ₂ , LiI— _{Li 2 S-P 2 S 5} , LiI-Li 2 S-B 2 S 3, Li 3 PO 4 -Li 2 S-Si 2 S, Li 3 PO 4 -Li 2 S-SiS 2, Li 3 PO 4 - _{Li 2 S-SiS, LiI-} Li 2 S-P 2 O 5, LiI-Li 3 PO 4 -P 2 S 5, Li 2 S-P 2 S 5 sulfide amorphous solid electrolyte material, such as, LiI, _{LiI-Al 2 O 3, Li} 3 N, Li 3 N- _{iI-LiOH, Li 1 + x} Al x Ti 2-x (PO 4) 3 (0 ≦ x ≦ 2), Li 1 + x + y A x Ti 2-x Si y P 3-y O 12 (A = Al or Ga, 0 ≦ x ≦ 0.4, 0 <y ≦ 0.6), [(A _1/2 Li _1/2 ) _1−x B _x ] TiO ₃ (A = La, Pr, Nd, Sm, B = Sr or Ba , 0 ≦ x ≦ 0.5), 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 / 2x)} N _x ( Examples thereof include crystalline oxides and oxynitrides such as x <1) and Li _3.6 Si _0.6 P _0.4 O ₄ . The thickness of the solid electrolyte layer is preferably in the range of 0.1 μm to 1000 μm, for example, and more preferably in the range of 0.1 μm to 300 μm.

  Moreover, the electrode body of this invention is used for an all-solid-state secondary battery. Examples of the all solid secondary battery include, for example, an all solid lithium secondary battery, an all solid sodium secondary battery, an all solid magnesium secondary battery, and an all solid calcium secondary battery. A lithium secondary battery is preferred.

B. Next, the all solid state secondary battery of the present invention will be described. The all-solid-state secondary battery of the present invention is characterized by having the electrode body for an all-solid-state secondary battery described above.

  FIG. 3 is a schematic cross-sectional view showing an example of the all solid state secondary battery of the present invention. An all solid secondary battery 20 shown in FIG. 3 includes a positive electrode active material layer 11, a negative electrode active material layer 12, a solid electrolyte layer 13 formed between the positive electrode active material layer 11 and the negative electrode active material layer 12, A positive electrode current collector 14 that collects current from the positive electrode active material layer 11 and a negative electrode current collector 15 that collects current from the negative electrode active material layer 12 are provided. The solid secondary battery 20 shown in FIG. 3 is a battery using the electrode body 10 having the positive electrode current collector 14 and the positive electrode active material layer 11.

According to the present invention, by using the electrode body for an all-solid-state secondary battery described above, an all-solid-state secondary battery that suppresses separation between the active material layer and the current collector, destruction of the active material layer, and the like is provided. Can do. The all-solid-state secondary battery of the present invention has at least a power generation element of a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, and the above-mentioned “A. Electrode body for all-solid-state secondary battery”. A battery having the described electrode body.
Hereinafter, the all-solid-state secondary battery of the present invention will be described for each configuration.

1. Positive electrode active material layer The positive electrode active material layer in the present invention is a layer containing at least a positive electrode active material. Moreover, in this invention, it is preferable that a positive electrode active material layer is the electrode body for all-solid-state secondary batteries mentioned above. When the negative electrode active material layer is the electrode body for an all-solid secondary battery described above, the positive electrode active material layer may be a thin film type active material layer, and a bulk type active material formed by compacting powder. It may be a material layer.

2. Negative electrode active material layer The negative electrode active material layer in the present invention is a layer containing at least a negative electrode active material. Moreover, in this invention, it is preferable that a negative electrode active material layer is the electrode body for all-solid-state secondary batteries mentioned above. When the positive electrode active material layer is the electrode body for an all-solid secondary battery described above, the negative electrode active material layer may be a thin film type active material layer, and a bulk type active material formed by compacting powder. It may be a material layer.

3. Solid electrolyte layer The solid electrolyte layer in the present invention is a layer containing at least a solid electrolyte material. In the present invention, the solid electrolyte layer may be a thin film type solid electrolyte layer or a bulk type solid electrolyte layer formed by compacting powder.

4). All-solid secondary battery The all-solid-state secondary battery of the present invention is preferably a thin-film battery in which the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are all thin films. This is because the size of the battery can be reduced.

C. Next, the manufacturing method of the electrode body for all-solid-state secondary batteries of this invention is demonstrated. The method for producing an electrode body for an all-solid-state secondary battery of the present invention includes an active material layer forming step of forming a thin film type active material layer on a current collector, and the current collector has a Vickers hardness of the above It is lower than the Vickers hardness of the active material layer and is in the range of 40 to 600.

  FIG. 4 is a schematic cross-sectional view showing an example of a method for producing an electrode body for an all-solid-state secondary battery of the present invention. In FIG. 4, first, the current collector 1 is prepared (FIG. 4A). Next, an electrode body 10 for an all-solid-state secondary battery is obtained by forming a thin film type active material layer 2 on the current collector 1 (FIG. 4B). The present invention is greatly characterized in that the current collector 1 has a Vickers hardness lower than the Vickers hardness of the active material layer 2 and in the range of 40 to 600.

  According to the present invention, since the Vickers hardness of the current collector is lower than the Vickers hardness of the active material layer, it is possible to obtain an electrode body in which stress generated between the active material layer and the current collector is relaxed. In addition, since the current collector is soft, the active material particles can easily bite into the current collector when the active material layer is formed, and an active material layer having excellent adhesion to the current collector can be formed. The Vickers hardness of the current collector and the active material layer is the same as that described in the above-mentioned “A. Electrode body for all-solid-state secondary battery”, and the description is omitted here.

  The active material layer forming step in the present invention is a step of forming a thin film type active material layer on the current collector. The film formation method of the active material layer is not particularly limited as long as an active material layer having a specific Vickers hardness is obtained, such as an aerosol deposition method, a gas deposition method, a thermal spray method, a cold spray method, etc. Can be mentioned. Moreover, PVD methods, such as sputtering method, may be used.

  Among these, in the present invention, it is preferable to form an active material layer by an aerosol deposition method (AD method). In the AD method, when the raw material particles collide with the substrate, a very high pressure of, for example, 3 GPa or more is applied. Therefore, a very dense and highly crystalline film can be formed in spite of being formed by a room temperature process. Further, since a high pressure is applied only to a very limited area of the substrate, there are advantages that damage to the substrate is small and mutual diffusion due to heat does not occur. In addition, the AD method uses a “normal temperature impact solidification phenomenon” (a phenomenon in which a mechanical impact force is simply applied to the raw material particles and solidifies at a high temperature at normal temperature without heating). Can be obtained. Furthermore, although it depends on the material of the film, there is also an advantage that the film forming speed is several tens of times that of the conventional thin film forming technique.

  FIG. 5 is a schematic diagram for explaining the aerosol deposition method (AD method). In FIG. 5, a pedestal 22 is installed inside the chamber 21, and a substrate 23 is disposed on the pedestal 22. In the present invention, a current collector is used as the substrate 23. Moreover, the pressure inside the chamber 21 can be controlled to an arbitrary reduced pressure state by the rotary pump 24. On the other hand, the raw material particles 26 are aerosolized by the carry-in gas supplied from the gas cylinder 25 inside the aerosol generator 27. Further, the aerosolized raw material particles are sprayed toward the substrate 23 from the nozzle 28 disposed inside the chamber 21. On the surface of the substrate 23, deposition occurs along with the destructive deformation of the particles, and a thin film is formed.

In the AD method, raw material particles containing active material particles are used. The average particle diameter (d ₅₀ ) of the raw material particles is not particularly limited, but is preferably in the range of 0.1 μm to 5.0 μm, for example, in the range of 0.5 μm to 2.0 μm. Is more preferable. The average particle diameter of the raw material particles can be determined by, for example, a particle size distribution meter. In order to adjust the average particle diameter of the raw material particles, it is preferable to perform refinement by mechanical milling (for example, a ball mill), predetermined classification, or the like.

  The pressure P at the time of film formation by the AD method is not particularly limited as long as it is a pressure capable of obtaining a desired density. For example, the pressure P is preferably higher than 100 Pa, more preferably 120 Pa or higher, and 150 Pa. More preferably, it is the above. This is because if the pressure during film formation is too low, the density of the active material layer may become too large. On the other hand, the pressure P is preferably 400 Pa or less, and more preferably 350 Pa or less, for example. This is because if the pressure during film formation is too high, it may be difficult to obtain a dense active material layer.

The type of carrier gas in the AD method, but not limited, helium (He), argon (Ar), nitrogen (N ₂₎ an inert gas, such as, and can include dry air, or the like. Also, the gas flow rate of the carrier gas is not particularly limited as long as it is a flow rate capable of maintaining a desired aerosol. For example, 3 L / min. ~ 8L / min. It is preferable to be within the range.

  In the present invention, a solid electrolyte layer forming step of forming a thin-film solid electrolyte layer on the active material layer may be performed. By forming a thin film type solid electrolyte layer, a useful member of a thin film battery can be obtained. The method for forming the solid electrolyte layer is not particularly limited, and a method similar to the method for forming the active material layer described above can be used. In particular, in the present invention, it is preferable to form a solid electrolyte layer by the AD method.

D. Next, the manufacturing method of the all-solid-state secondary battery of this invention is demonstrated. The manufacturing method of the all-solid-state secondary battery of this invention uses the electrode body for all-solid-state secondary batteries obtained by the manufacturing method of the electrode body for all-solid-state secondary batteries mentioned above.

  FIG. 6 is a schematic cross-sectional view showing an example of the method for producing the all solid state secondary battery of the present invention. In FIG. 6, an electrode body 10 having a positive electrode current collector 14, a positive electrode active material layer 11, and a solid electrolyte layer 13 is prepared (FIG. 6 (a)). Next, a thin-film negative electrode active material layer 12 is formed on the solid electrolyte layer 13 (FIG. 6B). Finally, the all-solid-state secondary battery 20 is obtained by disposing the negative electrode current collector 15 on the negative electrode active material layer 12.

  According to the present invention, by using the electrode body for an all-solid-state secondary battery described above, an all-solid-state secondary battery that suppresses separation between the active material layer and the current collector, destruction of the active material layer, and the like is obtained. Can do.

  Moreover, in this invention, an active material layer can be formed by arbitrary methods with respect to the electrode body for all-solid-state secondary batteries mentioned above, and a battery can be obtained. For example, when the electrode body for an all-solid-state secondary battery described above has a positive electrode current collector and a thin film type positive electrode active material layer, the solid electrolyte layer, the negative electrode active material layer, and the negative electrode current collector can be formed by any method. A body can be formed and a battery can be obtained. Among them, in the present invention, it is preferable to form at least one of the solid electrolyte layer and the negative electrode active material layer by the film forming method described in the above-mentioned “C. Method for producing electrode body for all-solid-state secondary battery”. It is preferable to form by AD method. The same applies to the case where the above-described electrode body for an all-solid-state secondary battery has a negative electrode current collector and a thin-film negative electrode active material layer.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
(Preparation of raw material particles)
First, as a positive electrode active material, commercially available lithium cobaltate (LiCoO ₂ , manufactured by Toda Kogyo Co., Ltd.) was prepared. Next, 150 g of lithium cobaltate was put into a zirconia pot (45 ml) together with zirconia balls (10 mmφ, 10 pieces), and the pot was completely sealed. The pot was attached to a planetary ball mill (P7 made by Fritsch) and subjected to mechanical milling for 4 hours at a base plate rotation speed of 250 rpm to refine the particles. Thereafter, powdery lithium cobalt oxide having an average particle size of 1.8 μm was obtained by predetermined classification.

Next, Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ (LATP) was prepared as a solid electrolyte material. Next, 150 g of LATP was placed in a zirconia pot (45 ml) together with zirconia balls (10 mmφ, 10 pieces), and the pot was completely sealed. The pot was attached to a planetary ball mill (P7 made by Fritsch) and subjected to mechanical milling for 4 hours at a base plate rotation speed of 250 rpm to refine the particles. Thereafter, powdery LATP having an average particle diameter of 1.2 μm was obtained by predetermined classification.

Next, commercially available lithium titanate (Li ₄ Ti ₅ O ₁₂ , manufactured by Ishihara Sangyo) was prepared as the negative electrode active material. Next, 150 g of lithium titanate was placed in a zirconia pot (45 ml) together with zirconia balls (10 mmφ, 10 pieces), and the pot was completely sealed. The pot was attached to a planetary ball mill (P7 made by Fritsch) and subjected to mechanical milling for 4 hours at a base plate rotation speed of 250 rpm to refine the particles. Thereafter, powdery lithium titanate having an average particle diameter of 0.8 μm was obtained by predetermined classification.

(Production of electrode body)
An Al alloy (Vickers hardness 140.5, thickness 0.1 mm) was prepared as a positive electrode current collector. Next, a positive electrode active material layer composed of lithium cobalt oxide was formed on the positive electrode current collector by an aerosol deposition method to obtain an electrode body. The film forming conditions are as follows.
<Film formation conditions>
・ Temperature Normal temperature ・ Pressure in the chamber about 1 Torr
・ Gas He
・ Gas flow rate 4L / min.
・ Scanning speed 2mm / sec.
The obtained positive electrode active material layer had a thickness of 4.2 μm and a Vickers hardness of 250.

(Production of battery)
On the positive electrode active material layer of the obtained electrode body, a solid electrolyte layer composed of LATP was formed by an aerosol deposition method. The film forming conditions are as follows.
<Film formation conditions>
・ Temperature Normal temperature ・ Pressure in the chamber about 1 Torr
・ Gas He
・ Gas flow rate 2.5L / min.
・ Scanning speed 2mm / sec.
The obtained solid electrolyte layer had a thickness of 5 μm.

Next, a negative electrode active material layer composed of lithium titanate was formed on the obtained solid electrolyte layer by an aerosol deposition method. The film forming conditions are as follows.
<Film formation conditions>
・ Temperature Normal temperature ・ Pressure in the chamber about 1 Torr
・ Gas He
・ Gas flow rate 4L / min.
・ Scanning speed 2mm / sec.
The obtained negative electrode active material layer had a thickness of 4 μm. Moreover, the Vickers hardness of the film | membrane with which the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer were laminated | stacked was 320.

  Finally, an Au thin film (negative electrode current collector) was formed on the obtained negative electrode active material layer by a sputtering method to obtain a battery.

[Example 2]
Commercially available lithium manganate (LiMn ₂ O ₄ , manufactured by Toda Kogyo Co., Ltd.) was prepared as a positive electrode active material. Next, 150 g of lithium manganate was placed in a zirconia pot (45 ml) together with zirconia balls (10 mmφ, 10 pieces), and the pot was completely sealed. The pot was attached to a planetary ball mill (P7 made by Fritsch) and subjected to mechanical milling for 4 hours at a base plate rotation speed of 250 rpm to refine the particles. Thereafter, powdery lithium manganate having an average particle size of 2.2 μm was obtained by predetermined classification. A battery was obtained in the same manner as in Example 1 except that this positive electrode active material was used. In addition, the obtained positive electrode active material layer had a thickness of 4 μm and a Vickers hardness of 550.

[Comparative Example 1]
Batteries were obtained in the same manner as in Example 1, except that SUS316L-H (Vickers hardness 452.9, thickness 0.1 mm) was used as the positive electrode current collector.

[Evaluation 1]
The batteries obtained in Examples 1 and 2 and Comparative Example 1 were subjected to a charge / discharge test under the conditions of a current density of 2.5 μA / cm ² , a voltage range of 0.3 V to 2.7 V, and 20 cycles. As a result, in Examples 1 and 2, even after the charge / discharge test, destruction of each layer including the positive electrode active material layer, separation between layers including the interface between the positive electrode current collector and the positive electrode active material layer did not occur. On the other hand, in Comparative Example 1, each layer was broken after the charge / discharge test. In Comparative Example 1, it was difficult to specify the destroyed layer strictly, but considering that the difference from Examples 1 and 2 is the positive electrode current collector, it was caused by the positive electrode active material layer. It was suggested that it was destruction. 7A is a photograph of a battery (Example 1) in which no destruction or peeling occurred, and FIG. 7B is a photograph of a battery in which total destruction occurred (Comparative Example 1). (C) is a photograph of a battery (Comparative Example 1) in which partial destruction occurred.

[Example 3]
First, a Cu alloy (Vickers hardness 95.6, thickness 1 mm) was prepared as a current collector. Next, an active material layer was formed on the current collector by an aerosol deposition method using the lithium cobalt oxide powder produced in Example 1 to obtain an electrode body. The film forming conditions are as follows.
<Film formation conditions>
・ Temperature Normal temperature ・ Pressure in the chamber about 1 Torr
・ Gas He
・ Gas flow rate 4L / min.
・ Scanning speed 2mm / sec.
The obtained active material layer had a thickness of 4.2 μm and a Vickers hardness of 250.

[Example 4]
An electrode body was obtained in the same manner as in Example 3 except that an Al alloy (Vickers hardness 140.5, thickness 0.1 mm) was used as the current collector.

[Reference Example 1]
An electrode body was obtained in the same manner as in Example 3 except that SUS304 (Vickers hardness 563.7, thickness 0.3 mm) was used as the current collector.

[Reference Example 2]
An electrode body was obtained in the same manner as in Example 3 except that Si (Vickers hardness 706.0, thickness 0.25 mm) was used as the current collector.

[Evaluation 2]
(Li ion conductivity measurement)
Li ion conductivity measurement was performed on the active material layers of the electrode bodies obtained in Examples 3 and 4 and Reference Examples 1 and 2. The measurement was performed by the AC impedance method.

(Crystal size measurement)
X-ray diffraction (XRD) measurement was performed on the active material layers of the electrode bodies obtained in Examples 3 and 4 and Reference Examples 1 and 2. From the full width at half maximum (FWHM) of the obtained peak, the crystal size of the lithium cobalt oxide particles contained in the active material layer was determined. The crystal size was calculated using the Scherrer equation.
D = Kλ / (βcosθ)
K: Scherrer constant, λ: wavelength, β: diffraction line broadening depending on crystallite size, θ: diffraction angle 2θ / θ

As shown in Table 1 and FIG. 8, when the current collector had a Vickers hardness of 600 or less, the Li ion conductivity was 1 × 10 ⁻⁴ S / cm or more, and good Li ion conductivity was exhibited. In Examples 3 and 4, the crystal size was as large as 14 nm or more. In particular, when the active material layer is formed by the aerosol deposition method, the raw material particles are pulverized by the impact pressure when colliding with the current collector, the crystal size of the raw material particles is refined, and the film itself is densified. At this time, if the current collector is too hard, the impact force at the time of the raw material particle collision becomes excessively large, and the crystal size is further refined more than necessary. As a result, it is considered that the crystal grain boundary density increases (crystallinity decreases) and ion conduction is inhibited. On the other hand, when the hardness of the current collector is too low, the crystal size of the particles contained in the film is not excessively refined, but the density of the film itself decreases. As a result, the Li ion conductivity of the film is considered to be low. Therefore, it is considered that there is a current collector hardness that maximizes the ionic conductivity of the membrane.

[Example 5]
An electrode body was obtained in the same manner as in Example 3, except that the lithium manganate powder prepared in Example 2 was used. The obtained active material layer had a thickness of 4 μm and a Vickers hardness of 550.

[Example 6, Reference Examples 3 and 4]
An electrode body was obtained in the same manner as in Example 4 and Reference Examples 1 and 2 except that the lithium manganate powder produced in Example 2 was used.

[Evaluation 3]
(Li ion conductivity measurement)
Li ion conductivity measurement was performed on the active material layers of the electrode bodies obtained in Examples 5 and 6 and Reference Examples 3 and 4. The evaluation method is the same as evaluation 2.

(Crystal size measurement)
X-ray diffraction (XRD) measurement was performed on the active material layers of the electrode bodies obtained in Examples 5 and 6 and Reference Examples 3 and 4. The evaluation method is the same as evaluation 2.

  In Table 2 and FIG. 9, the same tendency as in Table 1 was confirmed.

DESCRIPTION OF SYMBOLS 1 ... Current collector 2 ... Active material layer 3 ... Solid electrolyte layer 10 ... Electrode body for all-solid-state secondary battery 11 ... Positive electrode active material layer 12 ... Negative electrode active material layer 13 ... Solid electrolyte layer 14 ... Positive electrode current collector 15 ... Negative electrode current collector 20 ... All solid state secondary battery 21 ... Chamber 22 ... Base 23 ... Substrate 24 ... Rotary pump 25 ... Gas cylinder 26 ... Raw material particles 27 ... Aerosol generator 28 ... Nozzle

Claims (8)

A current collector, and a thin film type active material layer formed on the current collector,
Vickers hardness of the current collector, the lower than the Vickers hardness of the active material layer, and state, and are in the range of 40 to 600,
The current collector is Al, Al alloy, Cu or Cu alloy;
The active material layer is formed by an aerosol deposition method,
The active material layer is composed only of polycrystalline active material particles,
The active material particles are LiCoO ₂ or LiMn ₂ O ₄ ,
An electrode body for an all-solid-state secondary battery, wherein the active material particles have a crystallite size of 14 nm or more .   The active material particles are LiMn ₂ O ₄ The electrode body for an all-solid-state secondary battery according to claim 1, wherein:   The electrode body for an all-solid-state secondary battery according to claim 1, wherein the current collector is Cu or a Cu alloy.   An all-solid-state secondary battery comprising the electrode body for an all-solid-state secondary battery according to any one of claims 1 to 3. An active material layer forming step of forming a thin film type active material layer on the current collector by an aerosol deposition method ;
Vickers hardness of the current collector, the lower than the Vickers hardness of the active material layer, and state, and are in the range of 40 to 600,
The current collector is Al, Al alloy, Cu or Cu alloy;
The active material layer is composed only of polycrystalline active material particles,
The active material particles are LiCoO ₂ or LiMn ₂ O ₄ ,
The method for producing an electrode body for an all-solid-state secondary battery, wherein the crystallite size of the active material particles is 14 nm or more .   The active material particles are LiMn ₂ O ₄ The manufacturing method of the electrode body for all-solid-state secondary batteries of Claim 5 characterized by the above-mentioned.   The said current collector is Cu or Cu alloy, The manufacturing method of the electrode body for all-solid-state secondary batteries of Claim 5 or Claim 6 characterized by the above-mentioned.   An all-solid-state secondary battery electrode body obtained by the method for producing an all-solid-state secondary battery electrode body according to any one of claims 5 to 7 is used. A method for manufacturing a secondary battery.