JP2020071948A - Electrode laminated body, sintered body, and manufacturing method thereof - Google Patents

Abstract

To provide a method of co-sintering an oxide including lithium and titanium having a spinel type crystal structure and an oxide having a NASICON type crystal structure while suppressing side reactions.SOLUTION: An electrode laminated body 11 is obtained by laminating an electrode layer 13 including an electrode active material and a separator layer 15 including a solid electrolyte in this order, and the electrode active material is an oxide which has a spinel type crystal structure, and in which the constituent element ratio is LiMTiO(0≤x≤2, 0<y≤2, 1≤z≤1.5, M is a divalent or trivalent metallic element other than titanium, and x+n×y+4×z=8 where the valence of M is n), and the solid electrolyte is an oxide that has a NASICON type crystal structure.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sintered body containing an electrode active material, which is used for an electrode of a lithium ion battery.

  Secondary batteries are used in mobile devices such as mobile phones and laptops, transportation machines such as automobiles and aircraft, and power storage devices such as for power leveling. There is. Currently, the practical secondary battery with the highest energy density is a lithium-ion battery, and research is underway to try to further increase the energy density while maintaining safety. As part of this, research is being conducted on all-solid-state batteries that use a solid electrolyte instead of an electrolytic solution.

  In an all-solid-state battery, the negative electrode, the electrolyte, and the positive electrode that make up the battery are all solid, so by repeatedly stacking the negative electrode layer, the separator layer (lithium ion conductive layer), the positive electrode layer, and the electron conductive layer, they are individually packaged. Since it is possible to manufacture a battery having a series structure without it, it is considered to be suitable for automobiles and power storage. Furthermore, the all-oxide type all-solid-state battery in which the negative electrode active material, the solid electrolyte, and the positive electrode active material are oxides can be expected to have effects on safety and high-temperature durability, in addition to improving energy density.

Further, as a solid electrolyte used for the separator layer of the all-oxide solid electrolyte, an oxide having a NASICON type crystal structure, in particular, LAGP (Li _{1 + x} Al _x Ge _{2 -x} (PO ₄ ) ₃ ) is known. .. On the other hand, since LAGP contains Ge as a constituent element and is expensive, an oxide containing lithium, zirconium, and phosphorus having a NASICON type crystal structure such as LZP (LiZr ₂ (PO ₄ ) ₃ ) is an alternative material to LAGP. Is getting attention. While LAGP can be sintered at about 550 ° C, LZP requires sintering at a higher temperature of 600 ° C or higher, preferably 800 ° C to 1000 ° C.

  Ions move smoothly between the electrode active material in the electrode and the solid electrolyte in the separator layer, or between the electrode active material in the electrode and the solid electrolyte, because the all-solid-state battery uses the solid electrolyte instead of the electrolytic solution. You need to be in close contact so that you can. In order to form a structure in which the electrode active material and the solid electrolyte are in intimate contact with each other, the electrode active material and the solid electrolyte are sintered together (hereinafter sometimes referred to as co-sintering). There is.

As an electrode active material of an all-oxide type all-solid-state battery, lithium and titanium having a spinel type crystal structure such as lithium titanate Li ₄ Ti ₅ O ₁₂ (hereinafter, also referred to as “LTO”) described in Patent Document 1 is included. Oxides are known. It is widely recognized that LTO is an excellent electrode active material because it has excellent electrochemical properties, small expansion and contraction during charge and discharge, and does not contain expensive transition metals. Patent Document 1 discloses a battery sintered body that can obtain good charge-discharge characteristics even if a different phase occurs in co-sintering of LTO and LAGP.

Patent Document 2 discloses a laminated body of an electrode layer containing spinel type lithium titanate and a separator layer containing Li ₃ PO ₄ or the like. Patent Document 3 discloses a laminate of a positive electrode active material layer containing a spinel type oxide containing at least one of Ni and Mn and a separator layer containing a Nasicon type phosphoric acid compound. Further, in Patent Document 4, in a laminate of a negative electrode layer containing spinel type lithium titanate and a solid electrolyte layer (separator layer) containing a Nasicon type solid electrolyte, the solid electrolyte of the separator layer is a Nasicon type LiZr ₂ (PO ₄ ) ₃ or a LiZr ₂ (PO ₄ ) ₃ -containing layer is provided between the negative electrode layer and the separator layer to improve the reduction resistance of the solid electrolyte.

JP, 2012-104280, A JP, 2018-125286, A International publication 2012/043566 International publication 2011/065388

  However, when a mixture of LZP powder and LTO powder is co-sintered at 600 ° C. or higher, LZP and LTO react with each other, LZP and LTO are decomposed, and an impurity layer causing electric resistance is formed. There was a problem to do. Decomposition of materials and generation of impurities, which occur when such materials are sintered together, are sometimes called side reactions. It may be called a reaction product.

  Further, in Patent Document 1, by mixing LTO powder and LAGP powder and then sintering at 550 ° C. to 650 ° C., a sintered body having both LAGP and LTO is obtained, but the interface between LTO and LAGP is obtained. These react with each other to generate a different phase (side reaction product). However, in co-sintering, it is generally said that the side reaction products generated at the interface between the solid electrolyte material and the active material material impede the movement of ions, and the charge-discharge characteristics of the battery sintered body are significantly deteriorated. There's a problem.

In Patent Document 2, the separator layer solid electrolyte is not a NASICON type oxide. Further, in Patent Document 3, the active material material is LiNi _0.5 Mn _1.5 O ₄ or the like, and is not an oxide containing lithium and titanium. In Patent Document 4, an example in which another material such as LiZr ₂ (PO ₄ ) ₃ and LTO is actually co-sintered is not carried out, and according to the study of the present inventor, LTO and LiZr When co-sintering ₂ (PO ₄ ) ₃ , side reaction products are considered to occur.

  The present invention finds a material composition in which a side reaction product is unlikely to occur in a sintered body of an oxide containing lithium and titanium having a spinel type crystal structure and an oxide having a NASICON type crystal structure, and these materials. It is an object of the present invention to provide a method for co-sintering the composition while suppressing side reactions.

  As a result of earnest studies, the present inventors have found that an oxide obtained by substituting a part of lithium atoms and / or titanium atoms constituting LTO with another metal is more solid than LTO when co-sintered with a solid electrolyte. They have found that they do not easily react with an electrolyte, and have completed the present invention.

Specifically, the present invention comprises an electrode layer containing an electrode active material, and a separator layer containing a solid electrolyte laminated in this order, the electrode active material has a spinel type crystal structure, the constituent element ratio is _{li x M y Ti z О 4} (0 ≦ x ≦ 2,0 <y ≦ 2,1 ≦ z ≦ 1.5, M is an n-valent divalent or trivalent metallic element other than titanium, the valence of M Is x + n × y + 4 × z = 8), and the solid electrolyte is an oxide having a Nasicon type crystal structure.

  According to the present invention, it is possible to suppress the production of a side reaction product in a sintered body of an oxide containing lithium and titanium having a spinel type crystal structure and an oxide having a NASICON type crystal structure. It is possible to provide a method of co-sintering while suppressing side reactions.

The figure which shows the electrode laminated body 11 which concerns on embodiment of this invention. The figure which shows the electrode laminated body 21 which concerns on embodiment of this invention. The figure which shows the sintered compact 31 which concerns on embodiment of this invention.

  Hereinafter, the present invention will be described in detail, but the description of the constituents described below is an example of the embodiment of the present invention, and the specific contents are not limited thereto. Various modifications can be implemented within the scope of the gist.

<Electrode laminate>
As shown in FIG. 1, the electrode laminate 11 according to the embodiment of the present invention includes an electrode layer 13 containing an electrode active material and a separator layer 15 containing a solid electrolyte, which are laminated in this order. Both the electrode layer 13 and the separator layer 15 are sintered bodies.

The solid electrolyte contained in the separator layer 15 (hereinafter also referred to as the separator layer solid electrolyte) is an oxide having a NASICON type crystal structure. The oxide having a NASICON type crystal structure is not particularly limited, and LAGP (Li _{1 + x} Al _x Ge _2-x (PO ₄ ) ₃ (0 ≦ x ≦ 1)), LATP (Li _{1 + x} Al _x Ti _2-x (PO ₄ ) ₃ (0 ≦ x ≦ 1)), LZP (Li _{1 + 4x} Zr _2−x PO ₄ ) ₃ (0 ≦ x ≦ 0.4) and the like can be mentioned. In particular, the oxide having a NASICON type crystal structure preferably contains lithium, zirconium, phosphorus, and oxygen, and LZP or a substance in which a part of the metal element of LZP is replaced with another metal element is preferable. Examples of other metal elements include Na, Sr, Ca, Mg, La, Y, Sc, Ce, In, Al, Ge, Ti and V.

Electrode active material contained in the electrode layer 13 (hereinafter, sometimes referred to as the electrode layer electrode active material.) Has a spinel type crystal structure, constituent elements ratio _{Li x M y Ti z О 4} (0 ≦ x ≦ 2, 0 <y ≦ 2, 1 ≦ z ≦ 1.5, M is a divalent or trivalent metal element other than titanium, and x = n × y + 4 × z = 8 where n is the valence of M). It is an oxide. Examples of the metal element M include Mg, Cr, Zn, Co, Fe, Ni, Mn and Cu. It is preferable that the electrode active material is one selected from Li ₂ MgTi ₃ O ₈ , LiCrTiO ₄ , Li ₂ ZnTi ₃ O ₈ , Zn ₂ TiO ₄ , and Zn ₂ Ti ₃ O ₈ .

The electrode layer 13 may include a solid electrolyte in addition to the electrode layer electrode active material. The solid electrolyte contained in the electrode layer 13 (hereinafter, also referred to as the electrode layer solid electrolyte) is preferably an oxide having a perovskite type crystal structure, and lithium lanthanum titanate Li _3x having a perovskite type crystal structure. La _{2 / 3-x} TiO ₃ (0 ≦ x ≦ 1/6, also referred to as LLTO) is more preferable. In addition, a part of the elements forming the lithium lanthanum titanate may be replaced with another element, or the other element may be doped. As another element, Na, K, Rb, Ag, Tl, Mg, Sr, Ca, Ba, Nb, Ta, W, Ru, Cr, Mn, Fe, Co, Al, Ga, Si, Ge, Zr, hf, Pr, Nd, Sm, Gd, Dy, Y, Eu, Tb and the like, _{specifically, La (2/3) -x Sr x} Li x TiO 3, Li x La 2/3 Ti 1- such as _x Al _x O ₃ and the like.

The electrode laminated body 11 is preferably a sintered body obtained by integrally sintering the electrode layer 13 and the separator layer 15 in a laminated state. When integrally sintered, it is preferable that the interface between the electrode layer 13 and the separator layer 15 does not contain a side reaction product. The side reaction product is a compound produced by reaction or decomposition of the electrode active material and the solid electrolyte during sintering. When the interface does not contain a side reaction product, the strongest line intensity I of the side reaction product derived from the electrode active material in the diffraction pattern obtained by pulverizing the electrode laminate and performing powder X-ray diffraction measurement ₁ and the ratio of the strongest line intensity I ₂ of the electrode active material, I ₁ / I ₂ is 1 or less, and the strongest line intensity I ₃ of the side reaction product derived from the separator layer solid electrolyte and the separator layer The ratio of the strongest line intensity I ₄ of the solid electrolyte, I ₃ / I _4, is 1 or less. I ₁ / I ₂ and I ₃ / I ₄ are preferably 1 or less, and more preferably 0.7 or less.

  Since the electrode laminate according to the present embodiment uses a specific material for the electrode active material and the solid electrolyte, it is difficult to cause a side reaction even when the separator layer and the electrode layer are integrally sintered in a laminated state. You can As a result, since a side reaction product having high resistance does not exist between the separator layer and the electrode layer, lithium ion conductivity between the separator layer and the electrode layer can be increased.

<Another Embodiment of Electrode Laminate>
Further, as in the electrode laminated body 21 shown in FIG. 2, an intermediate layer 23 containing a solid electrolyte may be provided between the separator layer 15 and the electrode layer 13.

  As the solid electrolyte contained in the intermediate layer 23 (hereinafter, also referred to as intermediate layer solid electrolyte), the same material as the electrode layer solid electrolyte can be used.

  By having the intermediate layer 23, a side reaction between the separator layer 15 and the electrode layer 13 can be further suppressed.

<Method for manufacturing electrode laminate>
The electrode laminate 11 includes a layer including an electrode layer electrode active material or a precursor thereof (hereinafter also referred to as an electrode layer green sheet), a separator layer solid electrolyte or a precursor thereof (hereinafter referred to as a separator layer green sheet). It may be obtained by heat-treating a laminate (hereinafter, also referred to as a green sheet laminate) in which a layer containing (in some cases) is laminated in this order.

  To form a green sheet laminate, a slurry containing an electrode layer electrode active material or a precursor thereof is applied on a substrate and dried to form an electrode layer green sheet, and a separator layer solid electrolyte is further formed thereon. Alternatively, a method in which a slurry containing a precursor thereof is applied and dried to form a separator layer green sheet, the base material is peeled off, the binder is removed by heating, and a laminate is molded (sequential coating method) can be mentioned. .. Alternatively, the separator layer green sheet and the electrode layer green sheet are separately prepared, at least one of them is peeled off and bonded to the other, and pressure and / or heat are applied to bring them into close contact with each other to obtain a green sheet. There is also a method of obtaining a laminated body (compression bonding method). The slurry may contain a binder such as acrylic resin, PVA (polyvinyl alcohol), PVB (polyvinyl butyral), or the like.

  The electrode laminate 21 having the intermediate layer 23 includes an electrode layer green sheet, a layer containing an intermediate layer solid electrolyte or a precursor thereof (hereinafter, also referred to as an intermediate layer green sheet), and a separator layer green sheet. It can be obtained by heat-treating a green sheet laminated body in which and are laminated in this order.

  The heat treatment temperature is preferably 550 ° C. or higher and 1000 ° C. or lower, and more preferably 650 ° C. or higher and 900 ° C. or lower.

  As the atmosphere during the heat treatment, any of an air atmosphere, an inert atmosphere such as nitrogen, a highly oxidizing atmosphere such as oxygen, and a reducing atmosphere such as hydrogen can be used. Further, a reduced pressure environment or a pressurized environment may be used, and, for example, an environment in an absolute pressure range of 0.1 Pa to 1 MPa, preferably 1 Pa to 500 kPa can be used. Further, the temperature holding time can be appropriately changed according to the temperature and the like, but considering production efficiency and the like, it is preferably 48 hours or less, more preferably 24 hours or less. The temperature may be held for a short time of 1 hour or less, and the holding time may be set to 0 minute, and heating may be stopped immediately after reaching the target temperature. The cooling method is also not particularly limited, and natural cooling (cooling in the furnace) may be performed, cooling may be performed faster than natural cooling, and a step of maintaining a predetermined temperature for a predetermined time during cooling may be performed. It may be provided.

  The precursor of the electrode active material or the solid electrolyte is a material which becomes the electrode active material or the solid electrolyte by heat treatment.

Having a spinel type crystal structure, the precursor of the oxide constituent elements ratio of Li _x M _y Ti _z О ₄ may be a compound containing lithium and titanium and the metal element M, the lithium source and titanium source And a compound of the metal element M may be used. As the lithium source, a lithium halide, carbonate, hydroxide or the like can be used. As the titanium source or the compound of the metal element M, oxides, halides, carbonates, hydroxides or the like of titanium or the metal element M can be used.

  The precursor of the oxide having a NASICON type crystal structure and containing lithium, zirconium and phosphorus may be a compound containing lithium, zirconium and phosphorus, or may be a mixture of a lithium source, a zirconium source and a phosphorus source. Good. As the lithium source, a lithium halide, carbonate, hydroxide or the like can be used. As the zirconium source, zirconium oxide, halide, carbonate, hydroxide or the like can be used. As the phosphorus source, phosphorus oxides such as phosphorus pentoxide, phosphorus oxo acids such as phosphoric acid and phosphorous acid, and phosphates such as ammonium dihydrogen phosphate can be used. A composite salt such as lithium or zirconium phosphate may be used.

  The precursor of lithium lanthanum titanate may be a compound containing lithium, titanium and lanthanum, or a mixture of a lithium source, a titanium source and a lanthanum source. As the lithium source, a lithium halide, carbonate, hydroxide or the like can be used. As the titanium source, titanium oxide, halide, carbonate, hydroxide or the like can be used. As the lanthanum source, lanthanum chloride, oxychloride, hydroxide, oxide, nitrate or the like can be used.

<Composite sintered body>
Further, another embodiment of the present invention is a sintered body such as the sintered body 31 shown in FIG. 3, which includes a spinel type oxide 33 and a Nasicon type oxide 35. The spinel type oxide 33 can use the same material as the electrode active material contained in the electrode layer 13. The same material as the separator layer solid electrolyte described above can be used for the NASICON type oxide 35.

  The sintered body 31 can be obtained by heat-treating a molded body containing the spinel type oxide 33 or its precursor and the Nasicon type oxide 35 or its precursor. The conditions for the heat treatment can be the same as those for the electrode laminate 11.

  A powdery mixture of the spinel type oxide 33 or its precursor and the NASICON type oxide 35 or its precursor is placed in a mold and pressed, or formed into a sheet by coating, etc. A shaped body having a shape is obtained. When forming into a sheet, for example, a method of applying a slurry containing a mixture and drying the solvent can be considered. A plasticizer, a binder, a dispersant, etc. may be added to the slurry as needed. The molding pressure can be set to, for example, 100 MPa or more and 1000 MPa or less in a mold, and can be set to a linear pressure of 20 N / mm or more and 2000 N / mm or less by using a roll press or the like, for example.

<Lithium-ion battery>
The lithium-ion battery of the present invention is a negative electrode layer that stores and releases lithium ions, a separator layer that conducts lithium ions, and a positive electrode layer that stores and releases lithium ions are laminated in this order, and a negative electrode layer or a positive electrode layer. The electrode laminate 11 or 21 of the present invention can be used as the separator layer, and the sintered body 31 of the present invention can be used as the negative electrode layer or the positive electrode layer.

For example, if the electrode active material of the electrode layer 13 of the electrode stack 11 has a spinel type crystal structure, using an oxide constituent elements ratio of _{Li x M y Ti z О 4} , this oxide, lithium It is often used as a negative electrode active material for ion secondary batteries, but if a material that has a charge / discharge potential relatively less than lithium titanate, such as metallic lithium or a lithium alloy, is used as the counter electrode (negative electrode), it will become a positive electrode active material. It can be used as a substance. Further, the electrode laminated body can be used as an electrode of a primary battery by using metallic lithium, a lithium alloy or the like as a counter electrode. In the present invention, the lithium ion battery includes both a primary battery and a secondary battery, and is not only a battery using metal lithium or a lithium alloy as an electrode, but also an electric battery in which lithium ions move between a positive electrode and a negative electrode. Includes the entire chemical device.

  Further, in the lithium ion battery of the present invention, a current collector layer may be provided on the surfaces of the negative electrode layer and the positive electrode layer. The current collector layer is provided in the all-solid-state battery for exchanging electricity with the outside during charging and discharging, and is a material having electron conductivity, usually an electron conductive substance itself such as metal or carbon material, or an electron conductive substance. It is composed of a material in which is dispersed in a matrix made of oxide or the like. As the metal constituting the current collector layer, at least one metal selected from the group consisting of nickel, copper, silver, gold and the like can be used. The current collector layer can be obtained by applying a metal paste and firing it in an atmosphere containing a reducing gas containing hydrogen or the like. In the present invention, if the materials are appropriately selected, it is possible to obtain an all-solid-state battery by collectively sintering the current collector layer, the composite electrode, the separator layer, and the counter electrode layer in a laminated state.

As negative electrode layer or positive electrode layer and the separator layer, a lithium ion battery using the electrode stack 11 of the present invention, for example, a layer containing oxide or its precursor constituent elements ratio of Li _x M _y Ti _z О ₄ And a layer containing a separator layer solid electrolyte or a precursor thereof, and a layer containing an electrode active material or a precursor thereof serving as a counter electrode are laminated in this order to obtain a heat treatment. be able to.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the examples.

[Preparation of LiCrTiO ₄ particles]
Cr ₂ O ₃ , TiO ₂ , and LiOH.H ₂ O were mixed in a Li: Cr: Ti = 1.05: 1: 1 (molar ratio), put into a firing boat made of alumina, and exposed to air at 950 ° C. for 12 hours. Fired in the atmosphere. Then, it was mechanically disintegrated.
When powder X-ray diffraction measurement was performed on the obtained powder, a diffraction line identified by Li (CrTiO ₄ ) [ICDD number 01-086-1173] was detected.
The specific surface area of the obtained powder was measured and found to be 15.9 m ² / g.

[Preparation of Mg ₂ TiO ₄ Particles]
TiO ₂ and Mg (OH) ₂ were mixed at a ratio of Mg: Ti = 2: 1 (molar ratio), put into an alumina firing boat, and fired at 1400 ° C. for 10 hours in the atmosphere. Then, it was mechanically disintegrated.
When powder X-ray diffraction measurement was performed on the obtained powder, a diffraction line determined by Mg ₂ TiO ₄ [ICDD number 00-025-1157] was detected.
The specific surface area of the obtained powder was measured and found to be 7.7 m ² / g.

[Preparation of Li ₂ MgTi ₃ O ₈ Particles]
TiO ₂ , MgO, and Li ₂ CO ₃ were mixed at a Li: Mg: Ti = 2: 1: 3 (molar ratio), put into an alumina firing boat, and fired at 1100 ° C. for 8 hours in the atmosphere. Then, it was mechanically disintegrated.
When powder X-ray diffraction measurement was performed on the obtained powder, a diffraction line identified by Li ₂ MgTi ₃ O ₈ [ICDD number 01-089-1308] was detected.
The specific surface area of the obtained powder was measured and found to be 8.4 m ² / g.

[Preparation of LZP particles]
Li ₂ CO ₃ , ZrO ₂ , NH ₄ H ₂ PO ₄ , and Na ₂ CO ₃ were mixed with Li: Zr: Na: P = 1.15: 1.95: 0.05: 3 (molar ratio), and alumina was mixed. It was put in a baking boat made of a ceramics, and pre-baked at 500 ° C. for 1 hour and then at 800 ° C. for 6 hours in an air atmosphere. After that, the obtained powder was mechanically crushed and subjected to main calcination at 1200 ° C. for 20 hours in an air atmosphere.
When powder X-ray diffraction measurement was performed on the obtained powder, a diffraction line determined by LiZr ₂ (PO ₄ ) ₃ [ICDD number 01-070-6734] was detected. It is considered that Li _1.15 Zr _1.95 Na _0.05 (PO ₄ ) ₃ having a Nasicon type crystal structure in which a part of Zr was substituted with Na was obtained from the composition charged.

[Example 1-1]
[Preparation of lithium lanthanum titanate (LLTO) particles]
Li ₂ CO ₃ , La (OH) ₃ and TiO ₂ were sampled at Li: La: Ti = 0.38: 0.56: 1 (molar ratio) and planetary ball mill (400 rpm / zirconia balls) in isopropyl alcohol. The mixture was mixed and ground for 4 hours. The obtained powder was separated from the balls and isopropyl alcohol and dried at 200 ° C. to obtain a raw material mixture. The obtained mixture was fired at 1150 ° C. for 2 hours in the air atmosphere.
When powder X-ray diffraction measurement was performed on the obtained powder, a diffraction line determined by LLTO [ICDD number 01-087-0935]] was detected.

[Preparation of electrode composite particles]
The LiCrTiO ₄ particles and the LLTO particles produced above were sampled at a weight ratio of 1: 1 and mixed and pulverized in isopropyl alcohol with a planetary ball mill (300 rpm / zirconia balls) for 9 hours. The obtained powder was separated from the balls and isopropyl alcohol and dried at 200 ° C. to obtain electrode composite particles.

[Production of electrode layer green sheet]
(Paste preparation process)
Polyvinyl butyral was dissolved in a mixed solvent of toluene and 2-propanol to prepare a binder solution. The above electrode composite particles were added to this binder solution and kneaded to prepare an electrode layer paste.

(Coating process)
The obtained electrode layer paste was applied onto a polyethylene terephthalate (PET) film by a doctor blade method and dried at 60 ° C. for 10 minutes to prepare an electrode layer green sheet.

[Preparation of intermediate layer particles]
The LLTO particles produced above were pulverized in isopropyl alcohol with a planetary ball mill (300 rpm / zirconia balls) for 9 hours. The obtained powder was separated from the balls and isopropyl alcohol and dried at 200 ° C to obtain intermediate layer particles.

[Preparation of intermediate layer green sheet]
An intermediate layer green sheet was produced by using the intermediate layer particles instead of the electrode composite particles in the same manner as in the production of the electrode layer green sheet.

[Preparation of Separator Layer Particles]
The LZP particles produced above were pulverized in isopropyl alcohol with a planetary ball mill (300 rpm / zirconia balls) for 9 hours. The obtained powder was separated from zirconia balls and isopropyl alcohol and dried at 200 ° C. to obtain separator layer particles.

[Preparation of separator layer green sheet]
A separator layer green sheet was prepared by using the separator layer particles instead of the electrode composite particles in the same manner as in the preparation of the electrode layer green sheet.

[Production of green sheet laminate]
The produced electrode layer green sheet, intermediate layer green sheet, and separator layer green sheet were cut into a disk shape having a diameter of 12 mm. On the cut electrode layer green sheet, an intermediate layer green sheet that has been cut and the PET film has been peeled off, and a separator layer green sheet that has been cut and the PET film has faced the upper surface are placed in this order, and at 80 ° C. with a thermocompression bonding device, After thermocompression bonding for 30 minutes, the uppermost and lowermost PET films were peeled off to prepare a green sheet laminate of electrode layer-intermediate layer-separator layer.

[Production of sintered body]
By sandwiching the green sheet laminate manufactured by the above method between alumina plates, removing polyvinyl butyral by pre-baking in the air at 500 ° C. for 10 hours, and then performing main baking in a nitrogen atmosphere at 700 ° C. for 12 hours. A sintered body was produced.

[Evaluation of sintered body]
It was confirmed that the layers of the sintered body produced by the above method were in close contact with each other, and an integrated laminate was obtained. When a powder X-ray diffraction measurement was performed by crushing the sintered body, LiCrTiO ₄ [ICDD number 01-086-1173], LLTO [ICDD number 01-087-0935], LiZr (PO ₄ ) ₃ [ICDD number 01 -070-6734] was detected.

[Example 1-2]
[Production and evaluation of sintered body]
A sintered body was produced in the same manner as in Example 1-1, except that the main firing temperature was 800 ° C.
It was confirmed that the layers of the sintered body produced by the above method were in close contact with each other, and an integrated laminate was obtained. When a powder X-ray diffraction measurement was performed by crushing the sintered body, LiCrTiO ₄ [ICDD number 01-086-1173], LLTO [ICDD number 01-087-0935], LiZr (PO ₄ ) ₃ [ICDD number 01 _-070-6734], ZrO 2 [ICDD No. _{01-070-6627],} LaPO 4 [ICDD No. _{01-084-0600], Li 3 PO 4 [} ICDD No. _{01-015-0760],} TiO 2 [ICDD No. 00 -021-1276] was detected.

[Example 1-3]
[Production and evaluation of sintered body]
A sintered body was produced in the same manner as in Example 1-1, except that the main firing temperature was 850 ° C.
It was confirmed that the layers of the sintered body produced by the above method were in close contact with each other, and an integrated laminate was obtained. When a powder X-ray diffraction measurement was performed by crushing the sintered body, LiCrTiO ₄ [ICDD number 01-086-1173], LLTO [ICDD number 01-087-0935], LiZr (PO ₄ ) ₃ [ICDD number 01 _-070-6734], ZrO 2 [ICDD No. _{01-089-9066],} LaPO 4 [ICDD No. _{01-084-0600], Li 3 PO 4 [} ICDD No. _{01-015-0760],} TiO 2 [ICDD No. 00 -021-1276] was detected.
The strongest ray intensity _{I 1} of TiO _2, and the ratio of the strongest ray intensity _{I 2 I} 1 _{/ I 2,} the strongest intensity _{I 3} of ZrO ₂ of LiCrTiO _4, the ratio of the strongest ray intensity _{I 4} of LZP _I 3 / It was set to I ₄ .

As described above, in Examples 1-1 to 1-3, the electrode layer containing LiCrTiO ₄ (corresponding to the electrode layer electrode active material) and LLTO (corresponding to the electrode layer solid electrolyte) and LLTO (intermediate layer solid electrolyte) were used. A laminated body of an intermediate layer containing the same and a separator layer containing LiZr (PO ₄ ) ₃ (separator layer solid electrolyte) was obtained.

[Mixed sintering test]
[Example 2]
A disk-shaped compact was prepared using the powder prepared by mixing the LiCrTiO ₄ particles and the LZP particles prepared above in a weight ratio of 1: 1. The sintered body was prepared by changing the firing temperature of the molded body to 600 ° C., 700 ° C. or 800 ° C. for 2 hours in the air atmosphere. When the sinter was crushed and subjected to powder X-ray diffraction measurement, diffraction lines determined by the components shown in the table below were detected. No side reaction products were detected in Examples 2-1 and 2-2 in which the firing temperatures were 600 ° C. and 700 ° C., but in Example 2-3 in which the firing temperature was 800 ° C., TiO ₂ and ZrO _{2 were produced.} Side reaction products such as ₂ and CrO ₂ were detected. The strongest ray intensity _{I 1} of TiO _{2, I} 1 / _{I 2} is the ratio of the strongest ray intensity _{I 2} of LiCrTiO ₄ is 0.18, and the strongest intensity _{I 3} of ZrO _2, the strongest intensity of LZP The ratio of I ₄ , I ₃ / I _4, was 0.19.

[Example 3]
A disk-shaped compact was prepared using the powder prepared by mixing the Mg ₂ TiO ₄ particles and the LZP particles prepared above in a weight ratio of 1: 1. The sintered body was prepared by changing the firing temperature of the molded body to 600 ° C., 700 ° C., 800 ° C. or 900 ° C. for 2 hours in the air atmosphere. When the sinter was crushed and subjected to powder X-ray diffraction measurement, diffraction lines determined by the components shown in the table below were detected. In Examples 3-1, 3-2, and 3-3 in which the firing temperatures were 600 ° C., 700 ° C., and 800 ° C., no side reaction product was detected, but the firing temperature in Example 3 was 900 ° C. In 4, the side reaction products such as ZrO ₂ and TiO ₂ were detected. The strongest ray intensity _{I 1} of TiO _{2, I} 1 / _{I 2} is the ratio of the strongest ray intensity _{I 2} of MgTiO ₄ is 0.12, and the strongest intensity _{I 3} of ZrO _2, the strongest intensity of LZP The ratio of I ₄ , I ₃ / I _4, was 0.62.

[Example 4]
A disk-shaped compact was created using the powder prepared by mixing the Li ₂ MgTi ₃ O ₈ particles and the LZP particles produced at the ratio of 1: 1 by weight. The sintered body was prepared by changing the firing temperature of the molded body to 600 ° C. and 700 ° C. for 2 hours in the air atmosphere. When the sintered body was crushed and subjected to powder X-ray diffraction measurement, diffraction lines that were determined by the components shown in the table below were detected. In Example 4-1, where the firing temperature was 600 ° C., no side reaction products other than Li ₂ MgTi ₃ O ₈ and LiZr ₂ (PO ₄ ) ₃ were detected, but the firing temperature was 700 ° C. In 4-2, side reaction products such as TiO ₂ were detected.

[Comparative Example 1]
A disk prepared by mixing commercially available spinel type Li ₄ Ti ₅ O ₁₂ (LTO) powder (specific surface area 7.5 m ² / g) and the LZP particles prepared above in a weight ratio of 1: 1 was used. A shaped body was formed. A sintered body was prepared by changing the firing temperature to 600 ° C., 700 ° C. or 800 ° C. for 2 hours in the air atmosphere of the molded body. When the sintered body was crushed and subjected to powder X-ray diffraction measurement, diffraction lines that were determined by the components shown in the following table were detected. In all of Comparative Examples 1-1 to 1-3, side reaction products such as anatase TiO ₂ were detected. The strongest ray intensity _{I 1} of the Comparative Example 1-3 in TiO _{2, I} 1 / _{I 2} is the ratio of the strongest ray intensity _{I 2} of the LTO is> 1, the strongest ray intensity _{I 3} of ZrO _2, LZP The ratio of the strongest line intensity I ₄ of I ₃ / I ₄ was 0.56.

From the above results, from Comparative Example 1, LTO and LZP cause a side reaction even at a firing temperature of 600 ° C., but LiCrTiO ₄ , Mg ₂ TiO ₄ , and Li ₂ MgTi ₃ O ₈ were used instead of LTO. In Examples 2 to 4, no side reaction product was detected even when calcined at 600 ° C. In particular, when Mg ₂ TiO ₄ was used as in Example 3, no side reaction product was detected even at 800 ° C.

That is, when obtaining a sintered body with LZP, when using LiCrTiO ₄ , Mg ₂ TiO ₄ , and Li ₂ MgTi ₃ O ₈ rather than LTO, the same 600 ° C., 700 ° C., and 800 ° C. were compared. As a result, I ₁ / I ₂ and I ₃ / I ₄ showing the amounts of the side reaction products were small, and it was found that the side reactions were suppressed.

DESCRIPTION OF SYMBOLS 11 Electrode laminated body 13 Electrode layer 15 Separator layer 21 Electrode laminated body 23 Intermediate layer 31 Sintered body 33 Nasicon type oxide 35 Spinel type oxide

Claims (15)

An electrode layer containing an electrode active material and a separator layer containing a solid electrolyte are laminated in this order,
The electrode active material has a spinel type crystal structure, constituent elements ratio _{Li x M y Ti z О 4} (0 ≦ x ≦ 2,0 <y ≦ 2,1 ≦ z ≦ 1.5, M is other than titanium Which is x + n × y + 4 × z = 8, where the valence of M is n and the valence of M is n).
An electrode laminate, wherein the solid electrolyte is an oxide having a Nasicon type crystal structure. The oxide having the spinel type crystal structure is one selected from LiCrTiO ₄ , Mg ₂ TiO ₄ , Li ₂ MgTi ₃ O ₈ , Li ₂ ZnTi ₃ O ₈ , Zn ₂ TiO ₄ , and Zn ₂ Ti ₃ O _8. The electrode laminate according to claim 1, wherein   The electrode laminate according to claim 1 or 2, wherein the oxide having the NASICON type crystal structure contains lithium, zirconium, phosphorus and oxygen. The electrode laminate is a sintered body integrally sintered in a state where the electrode layer and the separator layer are laminated,
In the diffraction pattern obtained by pulverizing the sintered body and performing powder X-ray diffraction measurement,
The ratio of the strongest line intensity I ₁ of the side reaction product derived from the electrode active material to the strongest line intensity I ₂ of the electrode active material, I ₁ / I ₂ is 1 or less, and the solid contained in the separator layer. claim that the strongest ray intensity I ₃ of the side reaction products derived from the electrolyte, the ratio of the strongest ray intensity I ₄ of the solid electrolyte contained in the separator layer, characterized in that I 3 _/ I ₄ is less than or equal to 1 The electrode laminate according to any one of 1 to 3.   The electrode layered product according to any one of claims 1 to 4, wherein the electrode layer further contains a solid electrolyte.   The electrode stack according to claim 5, wherein the solid electrolyte contained in the electrode layer is an oxide having a perovskite type crystal structure.   The electrode laminate according to any one of claims 1 to 6, further comprising an intermediate layer containing a solid electrolyte between the electrode layer and the separator layer. The electrode layer further contains lithium lanthanum titanate having a perovskite type crystal structure as a solid electrolyte,
The solid electrolyte contained in the intermediate layer is lithium lanthanum titanate having a perovskite type crystal structure,
The electrode laminate according to claim 7, wherein the electrode layer, the intermediate layer, and the separator layer are laminated in this order. It is a manufacturing method of the electrode laminated body according to claim 1,
Having a spinel type crystal structure, constituent elements ratio _{Li x M y Ti z О 4} (0 ≦ x ≦ 2,0 <y ≦ 2,1 ≦ z ≦ 1.5, M is a divalent or trivalent than titanium Of the metal element of the above formula, x = n × y + 4 × z = 8 where n is the valence of M) or a layer containing a precursor thereof, and an oxide having a Nasicon type crystal structure or a precursor thereof. A method for manufacturing an electrode laminated body, comprising heat-treating a laminated body in which layers are laminated in this order.   The method for producing an electrode laminate according to claim 9, wherein the temperature of the heat treatment is 550 ° C or higher and 1000 ° C or lower.   The method for producing an electrode laminate according to claim 9, wherein the temperature of the heat treatment is more than 650 ° C and 900 ° C or less. A negative electrode layer including a negative electrode active material that absorbs and releases lithium, a separator layer that includes a solid electrolyte that conducts lithium, and a positive electrode layer that includes a positive electrode active material that absorbs and releases lithium are laminated in this order,
The negative active material or the positive electrode active material, has a spinel type crystal structure, constituent elements ratio _{Li x M y Ti z О 4} (0 ≦ x ≦ 2,0 <y ≦ 2,1 ≦ z ≦ 1.5 , M is a divalent or trivalent metal element other than titanium, and is an oxide of x + n × y + 4 × z = 8 where the valence of M is n).
The all-solid-state lithium battery, wherein the solid electrolyte is an oxide having a Nasicon type crystal structure. Having a spinel type crystal structure, constituent elements ratio _{Li x M y Ti z О 4} (0 ≦ x ≦ 2,0 <y ≦ 2,1 ≦ z ≦ 1.5, M is a divalent or trivalent than titanium Of the metal element of, x + n × y + 4 × z = 8, where M is n-valent).
An oxide having a NASICON type crystal structure,
A sintered body comprising:   The sintered body according to claim 13, wherein the oxide having a NASICON type crystal structure contains lithium, zirconium, and phosphorus. A method of manufacturing a sintered body according to claim 13,
Having a spinel type crystal structure, constituent elements ratio _{Li x M y Ti z О 4} (0 ≦ x ≦ 2,0 <y ≦ 2,1 ≦ z ≦ 1.5, M is a divalent or trivalent than titanium A metal element of the above, an oxide of which is x + n × y + 4 × z = 8 where the valence of M is n, or a precursor thereof, and an oxide having a Nasicon type crystal structure or a precursor thereof. A method for producing a sintered body, which comprises heat treatment.

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