All-solid-state battery and manufacturing method for the same

Abstract

To provide a low-resistance, high-efficiency all-solid-state battery and a manufacturing method for the same by suppressing the formation of high-resistance oxides at the interface between a solid electrolyte layer and a negative electrode active material layer or a positive electrode active material layer.SOLUTION: The all-solid-state battery includes at least a solid electrolyte layer, a negative electrode active material layer disposed in contact with one surface of the solid electrolyte layer, and a positive electrode active material layer disposed in contact with the other surface of the solid electrolyte layer. The negative electrode active material layer contains lithium titanate. At the interface between the negative electrode active material layer and the solid electrolyte layer, the concentration of titanium dioxide is 5 mass% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an all-solid-state battery and a method for manufacturing an all-solid-state battery. [Background technology]

[0002] Currently, commonly used lithium-ion secondary batteries have traditionally used electrolytes (electrolytic solutions) such as organic solvents as a medium for ion migration. However, lithium-ion secondary batteries that use electrolytic solutions have concerns about the leakage of the electrolyte. In addition, because organic solvents and other materials used in electrolytic solutions are flammable, there is a demand for safer batteries.

[0003] Therefore, in order to improve the safety of lithium ion secondary batteries, all-solid-state lithium ion secondary batteries (hereinafter simply referred to as all-solid-state batteries) have been proposed, which use a solid electrolyte instead of an electrolytic solution (see, for example, Patent Documents 1 and 2). The all-solid-state batteries disclosed in Patent Documents 1 and 2 include a laminate in which a positive electrode layer including a positive electrode active material layer and a positive electrode current collector, and a negative electrode layer including a negative electrode active material layer and a negative electrode current collector are alternately stacked with a solid electrolyte layer interposed therebetween.

[0004] Conventionally, such all-solid-state batteries have been formed by sintering a solid electrolyte layer and an anode active material layer or a cathode active material layer together through a heat treatment process at high temperatures, such as 700°C. This makes it easy for a reactive phase containing a highly resistive metal oxide that inhibits the movement of lithium ions to form at the interface between the solid electrolyte layer and the anode active material layer or the cathode active material layer. This has hindered the improvement of the output power of all-solid-state batteries.

[0005] In order to suppress the formation of such a reaction phase containing metal oxides, for example, Patent Document 3 discloses a process of decomposing metal oxides on the surface of the solid electrolyte layer formed during the manufacturing process by subjecting the surface of the solid electrolyte layer in contact with the active material layer to ion bombardment, high voltage application, electromagnetic wave irradiation, etc. This discloses a method for producing an all-solid-state battery with little highly resistive metal oxides at the interfaces between the solid electrolyte layer and the negative electrode active material layer or the positive electrode active material layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-108258 [Patent Document 2] International Publication No. 2020 / 105662 [Patent Document 3] Patent No. 4923261 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the method disclosed in Patent Document 3, an active material layer is formed by decomposing a metal oxide formed on the surface of a solid electrolyte layer, and therefore the constituent materials of the active material layer are limited to those composed of elements contained in the solid electrolyte layer, and there is a problem in that it is not possible to form an active material layer composed of any constituent other than the elements contained in the solid electrolyte layer.

[0008] Furthermore, the process of decomposing the metal oxides that have formed on the surface of the solid electrolyte layer requires long-term sputtering, such as 24 hours in a vacuum environment, which has led to the problem that it is not possible to practically, efficiently, and at low cost manufacture all-solid-state batteries with reduced metal oxides between the solid electrolyte layer and the active material layer.

[0009] The present invention has been made in view of the above-mentioned problems, and aims to provide a low-resistance, highly efficient all-solid-state battery and a method for manufacturing the all-solid-state battery by suppressing the generation of high-resistance oxides at the interfaces between a solid electrolyte layer and an anode active material layer or a cathode active material layer. [Means for solving the problem]

[0010] The all-solid-state battery and the method for manufacturing the all-solid-state battery according to one embodiment of the present invention propose the following means. (1) An all-solid-state battery according to a first aspect of the present invention is an all-solid-state battery including at least a solid electrolyte layer, an anode active material layer disposed in contact with one surface of the solid electrolyte layer, and a cathode active material layer disposed in contact with the other surface of the solid electrolyte layer, wherein the anode active material layer contains lithium titanate, and the concentration of titanium dioxide at the interface between the anode active material layer and the solid electrolyte layer is 5% by mass or less.

[0011] (2) A second aspect of the present invention provides an all-solid-state battery comprising at least a solid electrolyte layer, a negative electrode active material layer disposed in contact with one surface of the solid electrolyte layer, and a positive electrode active material layer disposed in contact with the other surface of the solid electrolyte layer, wherein the positive electrode active material layer is NMC(Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2), and the concentration of each of nickel oxide, manganese oxide, and cobalt oxide at the interface between the positive electrode active material layer and the solid electrolyte layer is 5 mass % or less.

[0012] (3) A third aspect of the present invention is characterized in that, in the all-solid-state battery of the first or second aspect, the solid electrolyte layer contains LiCGC (registered trademark: OHARA CORPORATION).

[0013] (4) A method for producing an all-solid-state battery according to a fourth aspect of the present invention is the method for producing an all-solid-state battery according to the first aspect, characterized in that it includes at least a first application step of applying a dispersion of a lithium titanate precursor to one surface of the solid electrolyte layer, and a negative electrode active material layer generation step of irradiating the lithium titanate precursor with ultraviolet pulse laser light to generate lithium titanate, thereby forming the negative electrode active material layer.

[0014] (5) A fifth aspect of the present invention relates to the method for producing an all-solid-state battery of the fourth aspect, wherein in the negative electrode active material layer forming step, the temperature of the solid electrolyte layer is in the range of 350°C or more and 450°C or less, and the output of the ultraviolet pulse laser light is 60 mJ / cm 2 More than 80mJ / cm 2 the frequency of the ultraviolet pulse laser light is in the range of 0.1 Hz to 10 Hz, and the wavelength of the ultraviolet pulse laser light is in the range of 220 nm to 266 nm.

[0015] (6) A method for producing an all-solid-state battery according to a sixth aspect of the present invention is the method for producing an all-solid-state battery according to the second aspect, characterized in that it includes at least a second coating step of coating another surface of the solid electrolyte layer with a dispersion of an NMC precursor, and a positive electrode active material layer forming step of irradiating the NMC precursor with ultraviolet pulsed laser light to generate NMC, thereby forming the positive electrode active material layer.

[0016] (7) A seventh aspect of the present invention relates to the method for producing an all-solid-state battery of the sixth aspect, wherein in the positive electrode active material layer forming step, the temperature of the solid electrolyte layer is in the range of 350°C or more and 450°C or less, and the output of the ultraviolet pulse laser light is 60 mJ / cm 2 More than 80mJ / cm 2 the frequency of the ultraviolet pulse laser light is in the range of 0.1 Hz to 10 Hz, and the wavelength of the ultraviolet pulse laser light is in the range of 220 nm to 266 nm.

[0017] (8) Aspect 8 of the present invention is characterized in that, in the method for producing an all-solid-state battery of aspect 4 or aspect 6, the number of irradiation pulses of the ultraviolet pulsed laser light is 10 or less. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a low-resistance, highly efficient all-solid-state battery and a method for manufacturing the all-solid-state battery by suppressing the generation of high-resistance oxides at the interfaces between the solid electrolyte layer and the negative electrode active material layer or the positive electrode active material layer. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the configuration of an all-solid-state battery according to one embodiment of the present invention. [Figure 2] FIG. 1 is an X-ray diffraction peak diagram showing the results of Verification Example 1. [Figure 3] FIG. 10 is an X-ray diffraction peak diagram showing the results of Verification Example 2. [Figure 4] FIG. 10 is an X-ray diffraction peak diagram showing the results of Verification Example 3. [Figure 5] FIG. 10 is an X-ray diffraction peak diagram showing the results of Verification Example 4. [Figure 6] FIG. 10 is an X-ray diffraction peak diagram showing the results of Verification Example 5. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an all-solid-state battery according to one embodiment of the present invention and a method for manufacturing the all-solid-state battery will be described with reference to the drawings. Note that the following embodiments are specifically described to provide a better understanding of the gist of the invention, and do not limit the present invention unless otherwise specified. Furthermore, the drawings used in the following description may show essential parts enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as those in reality.

[0021] (All-solid-state battery) FIG. 1 is a schematic cross-sectional view showing the configuration of an all-solid-state battery according to one embodiment of the present invention. The all-solid-state battery 1 of this embodiment includes a laminate 10, a first current collector (extraction electrode) 11, and a second current collector (extraction electrode) 12.

[0022] <Laminate> The laminate 10 is composed of a solid electrolyte layer 21, a negative electrode 24 consisting of a negative electrode active material layer 22 and a negative electrode 23 arranged in contact with one surface 21a of the solid electrolyte layer 21, and a positive electrode 28 consisting of a positive electrode active material layer 26 and a positive electrode 27 arranged in contact with the other surface 21b of the solid electrolyte layer 21, stacked in a stacking direction S.

[0023] The shapes of the layers constituting the laminate 10 are not limited to rectangular, but may be circular or irregular. Such a laminate 10 functions as a secondary battery that is charged and discharged by the exchange of ions between the negative electrode active material layer 22 and the positive electrode active material layer 26 via the solid electrolyte layer 21 .

[0024] <Solid electrolyte layer> The solid electrolyte layer 21 is a layer containing a solid electrolyte and disposed between the negative electrode active material layer 22 and the positive electrode active material layer 26. A solid electrolyte is a substance that can move ions by an externally applied electric field. For example, the solid electrolyte layer 21 conducts lithium ions and inhibits the movement of electrons. The solid electrolyte layer 21 may be, for example, a sintered body or a compressed body.

[0025] It is preferable to use a material with low electron conductivity and high lithium ion conductivity for the solid electrolyte constituting the solid electrolyte layer 21. The solid electrolyte may be any of an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a complex hydride-based solid electrolyte, and a halide-based solid electrolyte.

[0026] Specific examples of the solid electrolyte constituting the solid electrolyte layer 21 include Li2O-Al2O3-SiO2-P2O5-TiO2-based composite metal oxide (LiCGC), Li 2x Zr(SO4) x Cl4(x is 1.0~3.0), Li2ZrSO4I4, Li2ZrCO3Cl4, Li2Zr((COO)2) 0.5 Cl5, Li2Zr(CH3COO) 0.2 Cl 5.8, Li2Zr(CF3COO) 0.2 Cl 5.8 , Li2Zr(HCOO) 0.4 Cl 5.6 , Li2ZrBO2Cl5, Li2ZrBF4Cl5, Li3YSO4Cl4, Li3YCO3Cl4, Li3YBO2Cl5, Li3YBF4Cl5, Li 7-x PS 6-x Cl x (x is 1.0 to 1.9), Li 2x ZrO x Examples include Cl4 (x is 1.0 to 7.0), xLi2S-(100-x)P2S5 (x is 20 to 80), etc. In this embodiment, LiCGC is used as the solid electrolyte.

[0027] One surface 21a of the solid electrolyte layer 21 of this embodiment, that is, the interface between the negative electrode active material layer 22 and the solid electrolyte layer 21, has a titanium dioxide (TiO2) concentration of 5 mass % or less, preferably 2 mass % or less.

[0028] In a method for manufacturing an all-solid-state battery, which will be described later, a dispersion of lithium titanate precursor is applied to one surface 21a of the solid electrolyte layer 21, and then the surface 21a is irradiated with ultraviolet pulsed laser light under predetermined irradiation conditions, thereby making it possible to make the concentration of titanium dioxide at the interface between the negative electrode active material layer 22 and the solid electrolyte layer 21 as low as described above.

[0029] Titanium dioxide is an electrically highly resistive material, and by reducing the concentration of titanium dioxide at the interface between the negative electrode active material layer 22 and the solid electrolyte layer 21, it is possible to reduce the overall resistance value of the all-solid-state battery 1 and improve the charge / discharge characteristics.

[0030] In addition, the other surface 21b of the solid electrolyte layer 21 of this embodiment, i.e., the interface between the positive electrode active material layer 26 and the solid electrolyte layer 21, has a concentration of nickel oxide (NiO), manganese oxide (MnO, MnO), and cobalt oxide (CoO, CoO) of 5 mass % or less, preferably 2 mass % or less.

[0031] In a method for manufacturing an all-solid-state battery, which will be described later, a dispersion of an NMC precursor is applied to the other surface 21b of the solid electrolyte layer 21, and then the surface 21b is irradiated with ultraviolet pulsed laser light under predetermined irradiation conditions, thereby making it possible to set the concentrations of nickel oxide, manganese oxide, and cobalt oxide at the interface between the positive electrode active material layer 26 and the solid electrolyte layer 21 to the low concentrations described above.

[0032] Metal oxides such as nickel oxide, manganese oxide, and cobalt oxide are electrically highly resistant materials, and by lowering the concentration of these metal oxides at the interface between the positive electrode active material layer 26 and the solid electrolyte layer 21, it becomes possible to reduce the overall resistance value of the all-solid-state battery 1 and improve the charge / discharge characteristics.

[0033] <Negative electrode active material layer> The negative electrode active material layer 22 is disposed in contact with one surface 21a of the solid electrolyte layer 21. The negative electrode active material layer 22 is made of a material containing a negative electrode active material. The negative electrode active material layer 22 may further contain a binder and a conductive additive in addition to the negative electrode active material, as necessary.

[0034] The negative electrode active material constituting the negative electrode active material layer 22 is a material capable of reversibly absorbing and releasing lithium ions and inserting and desorbing lithium ions, and is selected from lithium titanate (Li4Ti5O 12 The materials selected include LTO (lithium tin oxide). LTO has a spinel structure and three-dimensional lithium ion diffusion channels, making it an anode active material with excellent power characteristics and high-temperature and low-temperature performance.

[0035] Examples of binders that may be contained in the negative electrode active material layer 22 include polyvinylidene fluoride (PVDF) or copolymers thereof, polytetrafluoroethylene (PTFE), polyamide (PA), polyimide (PI), polyamideimide (PAI), polybenzimidazole (PBI), polyethersulfone (PES), polyacrylic acid (PA) and copolymers thereof, metal ion crosslinked polyacrylic acid (PA) and copolymers thereof, maleic anhydride-grafted polypropylene (PP), maleic anhydride-grafted polyethylene (PE), and mixtures thereof. Among these, PTFE is particularly preferred as the binder.

[0036] The conductive additive that may be contained in the negative electrode active material layer 22 improves the electronic conductivity of the negative electrode active material layer 22. Known conductive additives can be used. Examples of conductive additives that can be used include carbon materials such as carbon black, graphite, carbon nanotubes, graphene, and carbon fibers; metals such as aluminum, copper, nickel, stainless steel, iron, and amorphous metals; conductive oxides such as ITO; and mixtures thereof. The conductive additive may be in the form of powder or fiber.

[0037] <Negative electrode> The negative electrode 23 is a current collector on the negative electrode side, and may be made of a highly conductive metal material, such as a metal or alloy containing at least one metal element selected from the group consisting of silver (Ag), palladium (Pd), gold (Au), platinum (Pt), aluminum (Al), copper (Cu), nickel (Ni), titanium (Ti), and stainless steel.

[0038] <Cathode active material layer> The positive electrode active material layer 26 is disposed in contact with the other surface 21b of the solid electrolyte layer 21. The positive electrode active material layer 26 is made of a material containing a positive electrode active material. The positive electrode active material layer 26 may further contain a binder and a conductive additive in addition to the positive electrode active material, as necessary.

[0039] The positive electrode active material constituting the positive electrode active material layer 26 is Li(Ni) that can reversibly undergo absorption and desorption, and insertion and desorption (intercalation and deintercalation) of lithium ions. 1 / 3 Mn 1 / 3 Co 1 / 3 )O2(NMC) is selected.

[0040] Specific examples of the binder and conductive additive that may be contained in the positive electrode active material layer 26 may be the same as the binder and conductive additive that may be contained in the negative electrode active material layer 22 described above.

[0041] <Positive electrode> The positive electrode 27 is a current collector on the positive electrode side, and may be made of a highly conductive metal material, such as a metal or alloy containing at least one metal element selected from the group consisting of silver (Ag), palladium (Pd), gold (Au), platinum (Pt), aluminum (Al), copper (Cu), nickel (Ni), titanium (Ti), and stainless steel.

[0042] According to the all-solid-state battery 1 of this embodiment configured as described above, by setting the concentration of titanium dioxide at the interface between the negative electrode active material layer 22 and the solid electrolyte layer 21 to 5% by mass or less, and by setting the concentration of any of nickel oxide, manganese oxide, and cobalt oxide at the interface between the positive electrode active material layer 26 and the solid electrolyte layer 21 to 5% by mass or less, it is possible to reduce the overall resistance of the all-solid-state battery 1 due to these highly resistive metal oxides, and to realize an all-solid-state battery 1 with improved charge / discharge characteristics.

[0043] (Manufacturing method of all-solid-state batteries) The method for manufacturing the all-solid-state battery 1 of the present embodiment as described above includes a first application step of applying a dispersion of lithium titanate precursor to one surface 21a of the solid electrolyte layer 21 to form the anode active material layer 22, and a negative electrode active material layer formation step of irradiating the surface 21a with ultraviolet pulsed laser light under predetermined conditions.

[0044] The method also includes a second application step of applying a dispersion of lithium titanate precursor to the other surface 21b of the solid electrolyte layer 21 to form the positive electrode active material layer 26, and a positive electrode active material layer formation step of irradiating the other surface 21b with ultraviolet pulse laser light under predetermined conditions.

[0045] <First coating process> In the first application step, a dispersion of a lithium titanate precursor, which is a precursor material before reaction, for forming the negative electrode active material layer 22 containing LTO is applied to one surface 21a of the solid electrolyte layer 21.

[0046] As lithium titanate precursors, titanate compounds such as metatitanic acid represented by TiO(OH)2 or TiO2·H2O, orthotitanic acid represented by Ti(OH)4 or TiO2·2H2O, and titanium alkoxides (titanium methoxide, titanium ethoxide, titanium butoxide) can be used.

[0047] As a solvent for dispersing these lithium titanate precursors, organic solvents such as methanol, ethanol, and propanol can be used. In this embodiment, as the dispersion liquid of the lithium titanate precursor, an organic solvent slurry of the lithium titanate precursor in which the above-mentioned lithium titanate precursor is uniformly dispersed in an organic solvent is used.

[0048] The method for applying the organic solvent slurry of the lithium titanate precursor to one surface 21a of the solid electrolyte layer 21 can be various application methods, such as application with a brush, application with a coater, or application by spin coating, and the application method is not particularly limited.

[0049] <Negative electrode active material layer formation process> In the negative electrode active material layer forming process, a precursor thin film obtained by appropriately drying the organic solvent slurry of lithium titanate precursor applied in the preceding first application process is irradiated with ultraviolet pulse laser light under predetermined conditions to cause a photoreaction of the lithium titanate precursor, thereby producing a negative electrode active material layer 22 containing LTO on one surface 21a of the solid electrolyte layer 21. The irradiation conditions for the ultraviolet pulse laser light in the negative electrode active material layer forming step are as follows. (1) The heating temperature of the solid electrolyte layer is in the range of 350°C to 450°C. (2) The output of the ultraviolet pulsed laser light is 60 mJ / cm 2 More than 80mJ / cm 2 The following range (3) The frequency of the ultraviolet pulsed laser light is in the range of 0.1 Hz to 10 Hz. (4) The wavelength of the ultraviolet pulsed laser light is in the range of 220 nm to 266 nm. By irradiating the ultraviolet pulsed laser light under these conditions, the concentration of high-resistance titanium dioxide (TiO2) at the interface between the generated negative electrode active material layer 22 and one surface 21a of the solid electrolyte layer 21 can be kept low, such as 5 mass % or less.

[0050] Such titanium dioxide is a highly electrically resistive material, and by reducing the concentration of titanium dioxide at the interface between the negative electrode active material layer 22 and the solid electrolyte layer 21, it is possible to reduce the overall resistance value of the all-solid-state battery 1 and improve the charge / discharge characteristics.

[0051] In this embodiment, in the negative electrode active material layer forming step, the solid electrolyte layer 21 was heated to 400°C by an infrared heater, and ultraviolet pulse laser light was irradiated uniformly onto the entire surface 21a of the solid electrolyte layer 21 by optical scanning or the like. An excimer laser device (wavelength 248 nm) was used as the light source for the ultraviolet pulse laser light. The output of the ultraviolet pulse laser light was set to 70 mJ / cm. 2 The frequency was set to 1 Hz, and each irradiation location was irradiated five times (5 pulses) with the ultraviolet pulse laser light.

[0052] As a result of carrying out the anode active material layer forming step under these conditions, the anode active material layer 22 made of LTO was formed in close contact with the one surface 21a of the solid electrolyte layer 21. Furthermore, analysis revealed that the concentration of high-resistance titanium dioxide formed at the interface between the one surface 21a of the solid electrolyte layer 21 and the anode active material layer 22 was 5 mass % or less.

[0053] <Second coating process> In the second application step, a dispersion of an NMC precursor, which is a precursor material before reaction, for forming a positive electrode active material layer 26 containing NMC is applied to the other surface 21b of the solid electrolyte layer 21.

[0054] The NMC precursor is Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, sulfates and nitrates of lithium transition metal oxides can be used.

[0055] As a solvent for dispersing these NMC precursors, organic solvents such as methanol, ethanol, and propanol can be used. In this embodiment, the NMC precursor dispersion liquid used was an organic solvent slurry of the NMC precursor, in which the above-described NMC precursor was uniformly dispersed in an organic solvent.

[0056] The organic solvent slurry of the NMC precursor can be applied to the other surface 21b of the solid electrolyte layer 21 by various application methods, such as application with a brush, application with a coater, or application by spin coating, and the application method is not particularly limited.

[0057] <Cathode active material layer formation process> In the positive electrode active material layer forming step, a precursor thin film, which is obtained by appropriately drying the organic solvent slurry of NMC precursor applied in the previous second application step, is irradiated with ultraviolet pulsed laser light under predetermined conditions to cause a photoreaction of the NMC precursor, thereby producing a positive electrode active material layer 26 containing NMC on the other surface 21b of the solid electrolyte layer 21. The irradiation conditions for the ultraviolet pulse laser light in the positive electrode active material layer forming step are as follows. (1) The heating temperature of the solid electrolyte layer is in the range of 350°C to 450°C. (2) The output of the ultraviolet pulsed laser light is 60 mJ / cm 2 More than 80mJ / cm 2 The following range (3) The frequency of the ultraviolet pulsed laser light is in the range of 0.1 Hz to 10 Hz. (4) The wavelength of the ultraviolet pulsed laser light is in the range of 220 nm to 266 nm. By irradiating the cathode with ultraviolet pulsed laser light under these conditions, the concentrations of nickel oxide (NiO), manganese oxide (MnO, MnO), and cobalt oxide (CoO, CoO) at the interface between the generated cathode active material layer 26 and the other surface 21b of the solid electrolyte layer 21 can all be kept low, such as 5% by mass or less.

[0058] Oxides of transition metals such as nickel, manganese, and cobalt are electrically highly resistant materials, and by reducing the concentration of oxides of these transition metals at the interface between the positive electrode active material layer 26 and the solid electrolyte layer 21, it is possible to reduce the overall resistance value of the all-solid-state battery 1 and improve the charge / discharge characteristics.

[0059] In this embodiment, in the positive electrode active material layer forming step, the solid electrolyte layer 21 was heated to 400°C by an infrared heater, and ultraviolet pulse laser light was irradiated uniformly onto the entire other surface 21b of the solid electrolyte layer 21 by optical scanning or the like. An excimer laser device (wavelength 248 nm) was used as the light source for the ultraviolet pulse laser light. The output of the ultraviolet pulse laser light was set to 70 mJ / cm. 2 The frequency was set to 1 Hz, and each irradiation location was irradiated five times (5 pulses) with the ultraviolet pulse laser light.

[0060] As a result of performing the positive electrode active material layer forming step under these conditions, a positive electrode active material layer 26 made of NMC was formed in close contact with the other surface 21b of the solid electrolyte layer 21. Furthermore, analysis revealed that the concentration of high-resistance transition metal oxide formed at the interface between the other surface 21b of the solid electrolyte layer 21 and the positive electrode active material layer 26 was 5 mass % or less.

[0061] After the negative electrode active material layer forming step and the positive electrode active material layer forming step, the negative electrode 23 and the first current collector (extract electrode) 11 are formed on the negative electrode active material layer 22, and the positive electrode 27 and the second current collector (extract electrode) 12 are formed on the positive electrode active material layer 262, thereby obtaining the all-solid-state battery 1 of this embodiment.

[0062] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Example]

[0063] The effects of the present invention were verified. <Verification of the negative electrode active material layer> (Verification example 1: Substrate temperature 1) A precursor film was formed by applying an organic solvent slurry of lithium titanate precursor to a SiO2 substrate simulating a solid electrolyte layer. An excimer laser (wavelength 248 nm) was used to irradiate this precursor film with an output of 70 mJ / cm. 2 The negative electrode active material layer containing LTO was formed by irradiating the substrate with ultraviolet pulse laser light at a frequency of 1 Hz. During the formation of this negative electrode active material layer, the substrate temperature was set to 400°C, 500°C, 600°C, 700°C, and 800°C, and the formed negative electrode active material layer was subjected to X-ray diffraction analysis. FIG. 2 shows the X-ray diffraction peaks under each substrate temperature condition.

[0064] According to the results shown in Figure 2, when the substrate temperature was 500°C or higher, a clear peak indicating titanium oxide was observed, confirming that high-resistance titanium oxide was formed. On the other hand, when the substrate temperature was 400°C, no clear peak indicating titanium oxide was observed, confirming that an LTO layer (negative electrode active material layer) that did not contain titanium oxide, which would increase the resistance, could be formed.

[0065] (Verification example 2: Substrate temperature 2) Output 50mJ / cm 2 The other conditions were the same as in Verification Example 1, but the substrate temperatures were set to 300° C. and 400° C., and the formed negative electrode active material layers were subjected to X-ray diffraction. Figure 3(a) shows the X-ray diffraction peaks at substrate temperatures of 300°C, and Figure 3(b) shows the X-ray diffraction peaks at substrate temperatures of 400°C.

[0066] According to the results shown in Figure 3, the formation of an LTO layer by irradiation with ultraviolet pulsed laser light was not confirmed when the substrate temperature was 300°C. On the other hand, it was confirmed that an LTO (negative electrode active material layer) could be formed when the substrate temperature was 400°C. However, titanium oxide was also produced at the same time.

[0067] (Verification example 3: UV pulse laser light output) A precursor film was formed by applying an organic solvent slurry of a lithium titanate precursor to a SiO2 substrate simulating a solid electrolyte layer. This precursor film was irradiated with ultraviolet pulsed laser light at a frequency of 1 Hz using an excimer laser device (wavelength 248 nm) at a substrate temperature of 400°C to form a negative electrode active material layer containing LTO. During the formation of this negative electrode active material layer, the output of the ultraviolet pulsed laser light was set to 50 mJ / cm. 2 and 70 mJ / cm 2 The negative electrode active material layer thus formed was subjected to X-ray diffraction. Figure 4(a) shows the 50 mJ / cm 2 , 70 mJ / cm in Fig. 4(b). 2 4 shows X-ray diffraction peaks under the output conditions of ultraviolet pulse laser light.

[0068] According to the results shown in Figure 4, the output of the ultraviolet pulsed laser light was 50 mJ / cm 2 On the other hand, when the output of the ultraviolet pulsed laser light was 70 mJ / cm, titanium oxide was also formed along with the formation of the LTO layer. 2 No clear peak indicating titanium oxide was observed, confirming that it was possible to form an LTO (negative electrode active material layer) that does not contain titanium oxide, which causes an increase in resistance value.

[0069] (Verification example 4: Frequency of ultraviolet pulsed laser light) A precursor film was formed by applying an organic solvent slurry of lithium titanate precursor to a SiO2 substrate simulating a solid electrolyte layer. This precursor film was then irradiated with an excimer laser (wavelength 248 nm) at a substrate temperature of 400°C and an output of 50 mJ / cm. 2 The negative electrode active material layer containing LTO was formed by irradiating the negative electrode active material layer with a pulsed ultraviolet laser beam of 1 Hz or 50 Hz. During the formation of the negative electrode active material layer, the frequency of the pulsed ultraviolet laser beam was set to 1 Hz and 50 Hz, respectively, and the formed negative electrode active material layer was subjected to X-ray diffraction. Figure 5 shows the X-ray diffraction peaks under each frequency condition.

[0070] According to the results shown in Figure 5, when the frequency of the ultraviolet pulsed laser light was 50 Hz, titanium oxide was also formed along with the formation of an LTO layer by irradiation with ultraviolet pulsed laser light. On the other hand, when the frequency of the ultraviolet pulsed laser light was 1 Hz, no clear peak indicating titanium oxide was observed, confirming that it was possible to form an LTO (negative electrode active material layer) that did not contain titanium oxide, which would cause an increase in resistance value.

[0071] <Verification of the positive electrode active material layer> (Verification example 5: Frequency of ultraviolet pulsed laser light) A precursor film was formed by applying an organic solvent slurry of the NMC precursor to a SiO2 substrate simulating a solid electrolyte layer. As an example of the present invention, an excimer laser device (wavelength 248 nm) was used to irradiate this precursor film at a substrate temperature of 400°C and an output of 70 mJ / cm. 2 The precursor film was irradiated with ultraviolet pulsed laser light having a frequency of 1 Hz to form a positive electrode active material layer containing NMC. As a comparative example, the precursor film was heat-treated at 700°C instead of being irradiated with ultraviolet pulsed laser light to form a positive electrode active material layer. Figure 6 shows the X-ray diffraction peaks under each formation condition.

[0072] 6, it was confirmed that in the example of the present invention in which ultraviolet pulse laser light was irradiated, an NMC (positive electrode active material layer) that does not contain titanium oxide, which causes an increase in resistance, could be formed. On the other hand, in the comparative example, various peaks were observed in addition to the peak indicating NMC, and it was confirmed that many impurities other than NMC were also generated by the heat treatment. [Industrial Applicability]

[0073] The all-solid-state battery and the method for manufacturing the all-solid-state battery of the present invention can suppress the generation of high-resistance oxides at the interfaces between the solid electrolyte layer and the negative electrode active material layer or the positive electrode active material layer, thereby contributing to the realization of a low-resistance, highly efficient all-solid-state battery. Therefore, the present invention has industrial applicability. [Explanation of symbols]

[0074] 1...All-solid-state battery (lithium all-solid-state secondary battery) 10...Laminate 11...First current collector (extraction electrode) 12...Second current collector (extraction electrode) 21...Solid electrolyte layer 22...Negative electrode active material layer 23...Negative electrode 26...Cathode active material layer 27...Positive electrode

Claims

1. An all-solid-state battery comprising at least a solid electrolyte layer, a negative electrode active material layer disposed in contact with one surface of the solid electrolyte layer, and a positive electrode active material layer disposed in contact with the other surface of the solid electrolyte layer, the negative electrode active material layer contains lithium titanate, an all-solid-state battery, wherein the concentration of titanium dioxide at the interface between the negative electrode active material layer and the solid electrolyte layer is 5 mass % or less;

2. An all-solid-state battery comprising at least a solid electrolyte layer, a negative electrode active material layer disposed in contact with one surface of the solid electrolyte layer, and a positive electrode active material layer disposed in contact with the other surface of the solid electrolyte layer, The positive electrode active material layer is NMC(Li(Ni １／３ Mn １／３ Co １／３ ) O ２ ), an all-solid-state battery, wherein the concentration of each of nickel oxide, manganese oxide, and cobalt oxide at the interface between the positive electrode active material layer and the solid electrolyte layer is 5 mass % or less;

3. 3. The all-solid-state battery according to claim 1, wherein the solid electrolyte layer contains LiCGC (registered trademark).

4. The method for producing the all-solid-state battery according to claim 1, a first application step of applying a dispersion of a lithium titanate precursor to one surface of the solid electrolyte layer; and a negative electrode active material layer generation step of irradiating the lithium titanate precursor with ultraviolet pulsed laser light to generate lithium titanate, thereby forming the negative electrode active material layer.

5. In the negative electrode active material layer forming step, the temperature of the solid electrolyte layer is in the range of 350° C. or more and 450° C. or less, and the output of the ultraviolet pulse laser light is 60 mJ / cm ２ More than 80mJ / cm ２ the frequency of the ultraviolet pulsed laser light is in the range of 0.1 Hz to 10 Hz, and the wavelength of the ultraviolet pulsed laser light is in the range of 220 nm to 266 nm.

6. The method for producing the all-solid-state battery according to claim 2, a second coating step of coating another surface of the solid electrolyte layer with a dispersion of an NMC precursor; and a positive electrode active material layer producing step of irradiating the NMC precursor with ultraviolet pulsed laser light to produce NMC, thereby forming the positive electrode active material layer.

7. In the positive electrode active material layer forming step, the temperature of the solid electrolyte layer is in the range of 350° C. or higher and 450° C. or lower, and the output of the ultraviolet pulse laser light is 60 mJ / cm ２ More than 80mJ / cm ２ the frequency of the ultraviolet pulsed laser light is in the range of 0.1 Hz to 10 Hz, and the wavelength of the ultraviolet pulsed laser light is in the range of 220 nm to 266 nm.

8. 7. The method for producing an all-solid-state battery according to claim 4, wherein the number of irradiation pulses of the ultraviolet pulsed laser light is 10 or less.

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