JP6705145B2 - Composite and method for producing composite - Google Patents
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- JP6705145B2 JP6705145B2 JP2015199133A JP2015199133A JP6705145B2 JP 6705145 B2 JP6705145 B2 JP 6705145B2 JP 2015199133 A JP2015199133 A JP 2015199133A JP 2015199133 A JP2015199133 A JP 2015199133A JP 6705145 B2 JP6705145 B2 JP 6705145B2
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- 239000002131 composite material Substances 0.000 title claims description 74
- 238000004519 manufacturing process Methods 0.000 title claims description 20
- 239000003792 electrolyte Substances 0.000 claims description 90
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 82
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 72
- 229910052744 lithium Inorganic materials 0.000 claims description 72
- 239000002994 raw material Substances 0.000 claims description 60
- 239000007784 solid electrolyte Substances 0.000 claims description 49
- 229910000659 lithium lanthanum titanates (LLT) Inorganic materials 0.000 claims description 40
- 239000002245 particle Substances 0.000 claims description 37
- 239000002243 precursor Substances 0.000 claims description 37
- 229910052746 lanthanum Inorganic materials 0.000 claims description 35
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 35
- 239000000843 powder Substances 0.000 claims description 35
- 239000010936 titanium Substances 0.000 claims description 33
- 238000010304 firing Methods 0.000 claims description 23
- 239000007773 negative electrode material Substances 0.000 claims description 23
- 229910052719 titanium Inorganic materials 0.000 claims description 13
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 12
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 3
- 229910052596 spinel Inorganic materials 0.000 claims description 3
- 239000011029 spinel Substances 0.000 claims description 3
- RJEIKIOYHOOKDL-UHFFFAOYSA-N [Li].[La] Chemical compound [Li].[La] RJEIKIOYHOOKDL-UHFFFAOYSA-N 0.000 claims 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 36
- 230000000052 comparative effect Effects 0.000 description 26
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 24
- 239000007790 solid phase Substances 0.000 description 21
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 20
- 229910001416 lithium ion Inorganic materials 0.000 description 20
- 239000000203 mixture Substances 0.000 description 18
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 15
- 238000005259 measurement Methods 0.000 description 14
- 238000002156 mixing Methods 0.000 description 13
- 239000002002 slurry Substances 0.000 description 13
- 239000005279 LLTO - Lithium Lanthanum Titanium Oxide Substances 0.000 description 11
- 239000007774 positive electrode material Substances 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 239000007791 liquid phase Substances 0.000 description 10
- 229910010413 TiO 2 Inorganic materials 0.000 description 9
- 239000011812 mixed powder Substances 0.000 description 9
- 238000002360 preparation method Methods 0.000 description 9
- 239000000243 solution Substances 0.000 description 9
- 238000000576 coating method Methods 0.000 description 8
- 239000011268 mixed slurry Substances 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- 239000011149 active material Substances 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 7
- -1 phosphoric acid compound Chemical class 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 239000004014 plasticizer Substances 0.000 description 6
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 6
- 238000003786 synthesis reaction Methods 0.000 description 6
- 239000004698 Polyethylene Substances 0.000 description 5
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- 238000013461 design Methods 0.000 description 5
- 230000001747 exhibiting effect Effects 0.000 description 5
- 239000004570 mortar (masonry) Substances 0.000 description 5
- 238000000465 moulding Methods 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 239000003960 organic solvent Substances 0.000 description 5
- 229920000573 polyethylene Polymers 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- GEGLCBTXYBXOJA-UHFFFAOYSA-N 1-methoxyethanol Chemical compound COC(C)O GEGLCBTXYBXOJA-UHFFFAOYSA-N 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 238000004528 spin coating Methods 0.000 description 4
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 3
- 238000005238 degreasing Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 239000011259 mixed solution Substances 0.000 description 3
- 239000008188 pellet Substances 0.000 description 3
- 238000010587 phase diagram Methods 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 238000000197 pyrolysis Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- 229910052723 transition metal Inorganic materials 0.000 description 3
- 150000003624 transition metals Chemical class 0.000 description 3
- XNWFRZJHXBZDAG-UHFFFAOYSA-N 2-METHOXYETHANOL Chemical compound COCCO XNWFRZJHXBZDAG-UHFFFAOYSA-N 0.000 description 2
- 229910018136 Li 2 Ti 3 O 7 Inorganic materials 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 238000000498 ball milling Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- SORGMJIXNUWMMR-UHFFFAOYSA-N lanthanum(3+);propan-2-olate Chemical compound [La+3].CC(C)[O-].CC(C)[O-].CC(C)[O-] SORGMJIXNUWMMR-UHFFFAOYSA-N 0.000 description 2
- 239000011572 manganese Substances 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N phosphoric acid Substances OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000001103 potassium chloride Substances 0.000 description 2
- 235000011164 potassium chloride Nutrition 0.000 description 2
- 239000011802 pulverized particle Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 229910018871 CoO 2 Inorganic materials 0.000 description 1
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 1
- KLARSDUHONHPRF-UHFFFAOYSA-N [Li].[Mn] Chemical compound [Li].[Mn] KLARSDUHONHPRF-UHFFFAOYSA-N 0.000 description 1
- SOXUFMZTHZXOGC-UHFFFAOYSA-N [Li].[Mn].[Co].[Ni] Chemical compound [Li].[Mn].[Co].[Ni] SOXUFMZTHZXOGC-UHFFFAOYSA-N 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 244000309464 bull Species 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000010344 co-firing Methods 0.000 description 1
- CKFRRHLHAJZIIN-UHFFFAOYSA-N cobalt lithium Chemical compound [Li].[Co] CKFRRHLHAJZIIN-UHFFFAOYSA-N 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical group [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- NZPIUJUFIFZSPW-UHFFFAOYSA-H lanthanum carbonate Chemical compound [La+3].[La+3].[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O NZPIUJUFIFZSPW-UHFFFAOYSA-H 0.000 description 1
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 description 1
- 239000003446 ligand Substances 0.000 description 1
- 150000002642 lithium compounds Chemical class 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical class [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- RSNHXDVSISOZOB-UHFFFAOYSA-N lithium nickel Chemical compound [Li].[Ni] RSNHXDVSISOZOB-UHFFFAOYSA-N 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000009461 vacuum packaging Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Description
本発明は、複合体及び複合体の製造方法に関する。 The present invention relates to a composite and a method for producing the composite.
従来、リチウム二次電池に用いられる固体電解質としては、例えば、チタン酸ランタンで構成された平均粒径が５０ｎｍ〜３００ｎｍの第１の粒子と、チタン酸リチウムで構成された平均粒径が１０ｎｍ〜５０ｎｍである第２の粒子とを含む組成物からなるものが提案されている（例えば、特許文献１参照）。この固体電解質では、比較的低温での焼結処理で効率よく固体電解質層を形成することができるとしている。 Conventionally, as a solid electrolyte used for a lithium secondary battery, for example, first particles composed of lanthanum titanate and having an average particle size of 50 nm to 300 nm, and an average particle size composed of lithium titanate of 10 nm to A composition comprising a second particle having a size of 50 nm has been proposed (see, for example, Patent Document 1). With this solid electrolyte, it is said that the solid electrolyte layer can be efficiently formed by a sintering process at a relatively low temperature.
一般的に、固体電解質を用いる全固体型リチウムイオン二次電池では、固体電解質と活物質層との固体−固体界面に起因するインピーダンスの大きさが課題である。固体電解質としては、高いリチウムイオン伝導性を有するチタン酸リチウムランタンがあるが、他の全個体電池用の固体電解質と同じく、活物質と固体電解質との界面にリチウムイオン伝導が低いリチウム化合物（抵抗層）が生成しやすく、その抵抗層生成は界面インピーダンス増加に直接反映する。しかしながら、特許文献１の固体電解質では、固体電解質の単体の性能向上を図るものであって、固体電解質が組み込まれる電池の性能向上、例えば、固体電解質と活物質との間の接合性などについては検討されていなかった。 Generally, in an all-solid-state lithium-ion secondary battery using a solid electrolyte, a problem is the magnitude of impedance due to the solid-solid interface between the solid electrolyte and the active material layer. As the solid electrolyte, there is lithium lanthanum titanate, which has high lithium ion conductivity, but like other solid electrolytes for all solid-state batteries, a lithium compound with a low lithium ion conductivity (resistance Layer) is easily generated, and the resistance layer generation directly reflects the increase in interface impedance. However, the solid electrolyte of Patent Document 1 is intended to improve the performance of the solid electrolyte alone, and to improve the performance of the battery in which the solid electrolyte is incorporated, for example, regarding the bondability between the solid electrolyte and the active material, etc. Had not been considered.
本発明は、このような課題に鑑みなされたものであり、リチウムイオン伝導性を発揮しつつ、第１層と第２層とをより良好に接合することができる複合体及びその製造方法を提供することを主目的とする。また、より薄い第２層を形成することができる複合体及びその製造方法を提供することを目的とする。 The present invention has been made in view of the above problems, and provides a composite that can more favorably bond the first layer and the second layer while exhibiting lithium ion conductivity, and a method for producing the same. The main purpose is to do. Moreover, it aims at providing the composite_body|complex which can form a thinner 2nd layer, and its manufacturing method.
上述した目的を達成するために鋭意研究したところ、本発明者らは、負極活物質層に含まれるリチウムをリチウム源としてチタン酸リチウムランタンを合成したところ、リチウムイオン伝導性を発揮しつつ、負極活物質層と固体電解質層との界面をより良好なものとすることができ、さらに、固体電解質層をより薄く作製することができることを見いだし、本発明を完成するに至った。 As a result of intensive research to achieve the above-mentioned object, the present inventors have synthesized lithium lanthanum titanate using lithium contained in the negative electrode active material layer as a lithium source, and while exhibiting lithium ion conductivity, the negative electrode It has been found that the interface between the active material layer and the solid electrolyte layer can be made better, and the solid electrolyte layer can be made thinner, and the present invention has been completed.
即ち、本発明の複合体は、
スピネル構造のチタン酸リチウムを含む第１層と、
ペロブスカイト構造のチタン酸リチウムランタンを含む緻密層を含み前記第１層上を被覆した第２層と、を備えたものである。
That is, the complex of the present invention is
A first layer containing lithium titanate having a spinel structure;
And a second layer including a dense layer containing lithium lanthanum titanate having a perovskite structure and covering the first layer.
本発明の複合体の製造方法は、
チタン酸リチウムを含む成形体または焼結体である第１層上にチタン源及びランタン源を含む原料を形成した原料形成体を作製する原料形成工程と、
前記原料形成体を焼成し前記第１層に起因するリチウムをも原料として利用して前記第１層上にペロブスカイト構造のチタン酸リチウムランタンを含む緻密層を少なくとも形成させる第２層形成工程と、を含むものである。
The method for producing the composite of the present invention is
A raw material forming step of producing a raw material forming body in which a raw material containing a titanium source and a lanthanum source is formed on the first layer which is a molded body or a sintered body containing lithium titanate;
A second layer forming step in which the material forming body is fired and at least a dense layer containing lithium lanthanum titanate having a perovskite structure is formed on the first layer by using lithium derived from the first layer as a material; Is included.
本発明の複合体及び複合体の製造方法は、リチウムイオン伝導性を発揮しつつ、第１層と第２層とをより良好に接合することができる。この理由は、例えば、第１層である負極活物質のチタン酸リチウム上でそれ自身の一部が第２層である電解質合成のためのチタン源、リチウム源となり、層状ペロブスカイト構造のチタン酸ランタン前駆体とその他の原料と反応するためであると推察される。このため、負極活物質上を緻密なペロブスカイト構造のチタン酸リチウムランタンで被覆し、固体電解質と活物質層との固体−固体界面が良好に接合した負極／電解質複合体となるものと推察される。また、本発明では、上述した反応により第２層が形成される際に、その厚みは従来よりもはるかに薄肉化されるものと推察される。 INDUSTRIAL APPLICABILITY The composite and the method for producing the composite of the present invention can more favorably bond the first layer and the second layer while exhibiting lithium ion conductivity. The reason for this is, for example, lanthanum titanate having a layered perovskite structure, which serves as a titanium source and a lithium source for electrolyte synthesis in which a part of itself is the second layer on the negative electrode active material lithium titanate which is the first layer. It is presumed that this is because it reacts with the precursor and other raw materials. Therefore, it is presumed that the negative electrode/electrolyte composite is obtained by covering the negative electrode active material with lithium lanthanum titanate having a dense perovskite structure, and satisfactorily bonding the solid-solid interface between the solid electrolyte and the active material layer. .. Further, in the present invention, when the second layer is formed by the above-mentioned reaction, the thickness thereof is presumed to be much thinner than the conventional one.
本発明の複合体は、スピネル構造のチタン酸リチウムを含む第１層と、ペロブスカイト構造のチタン酸リチウムランタンを含む緻密層を含み前記第１層上を被覆した第２層と、を備えたものである。ここで、第１層は、負極活物質層であり、第２層の緻密層は、固体電解質層であり、複合体は、負極／電解質複合体であるものとしてもよい。ここで、本明細書において、チタン酸リチウムをＬｉＴＯとも称し、チタン酸ランタンをＬａＴＯとも称し、チタン酸リチウムランタンをＬＬＴＯとも称するものとする。 The composite of the present invention comprises a first layer containing lithium titanate having a spinel structure, and a second layer including a dense layer containing lithium lanthanum titanate having a perovskite structure and covering the first layer. Is. Here, the first layer may be a negative electrode active material layer, the second dense layer may be a solid electrolyte layer, and the composite may be a negative electrode/electrolyte composite. Here, in the present specification, lithium titanate is also referred to as LiTO, lanthanum titanate is also referred to as LaTO, and lithium lanthanum titanate is also referred to as LLTO.
第１層に含まれるチタン酸リチウムは、基本組成式がＬｉ4Ｔｉ5Ｏ12であるものとしてもよく、Ｌｉ／Ｔｉ比（モル比）が０．８０１〜０．８３の範囲であることが好ましい。この第１層は、例えば第２層の支持体となるものとしてもよく、その厚さは、１μｍ以上１００μｍ以下の範囲であることが好ましい。 The lithium titanate contained in the first layer may have a basic composition formula of Li 4 Ti 5 O 12 and a Li/Ti ratio (molar ratio) of 0.801 to 0.83. preferable. This first layer may serve as a support for the second layer, for example, and its thickness is preferably in the range of 1 μm or more and 100 μm or less.
第２層に含まれる緻密層は、任意の寸法で第１層の上面の一部又は全部を被覆しており、第１層の上面に密着した構造を有する。第２層の緻密層は、厚さが０．０５μｍ以上１０μｍ以下の範囲で形成されていることが好ましい。第２層の厚さが０．０５μｍ以上では、十分な層を形成することができ、好ましい。また、第２層の厚さが１０μｍ以下では、第１層（例えば正極及び負極を含む）の厚さが相対的に厚くならず、エネルギー密度や出力密度をより良好にすることができる。この緻密層は、固体電解質として用いられる際は、負極と正極との短絡を防止できる厚さを有するものとすればより薄い方が好ましく、その厚さは、対象となる電池設計に因るが、８μｍ以下がより好ましく、５μｍ以下が更に好ましい。また、この緻密層の厚さは、０．５μｍ以上がより好ましく、１μｍ以上が更に好ましい。ペロブスカイト構造のチタン酸リチウムランタンは、組成式がＬａ2/3-xＬｉ3xＴｉＯ3（式中、ｘは０．０３以上０．１７以下の数を示す。)で表わされる斜方晶あるいは正方晶の結晶性化合物であることが好ましい。この第２層は、緻密層の上に形成されたペロブスカイト構造のチタン酸リチウムランタンを含む多孔質層をさらに含むものとしてもよい。この多孔質層は、例えば、正極活物質が充填される層であるものとしてもよい。こうすれば、Ｌｉの伝導をより好適に行うことができる。あるいは、この多孔質層上に正極活物質層が形成されるものとしてもよい。多孔質層は、例えば、厚さが１μｍ以上１００μｍ以下の範囲としてもよく、５０μｍ以下の範囲としてもよい。あるいは、第２層は、多孔質層を含まず、緻密層上に正極活物質層が形成されるものとしてもよい。なお、「緻密層」とは、断面視したときの緻密層全体の面積に対する空孔の面積の割合が５％以下であるものをいうものとする。また、「多孔質層」とは、緻密層に対して空孔の面積割合が大きいものをいうものとし、例えば断面視したときの多孔質層全体の面積に対する空孔の面積の割合が２０％以上であるものとしてもよい。 The dense layer included in the second layer covers a part or the whole of the upper surface of the first layer with an arbitrary size, and has a structure in which it is in close contact with the upper surface of the first layer. The dense layer of the second layer is preferably formed with a thickness of 0.05 μm or more and 10 μm or less. When the thickness of the second layer is 0.05 μm or more, a sufficient layer can be formed, which is preferable. When the thickness of the second layer is 10 μm or less, the thickness of the first layer (including, for example, the positive electrode and the negative electrode) is not relatively thick, and the energy density and the output density can be improved. When the dense layer is used as a solid electrolyte, it is preferable that the dense layer has a thickness capable of preventing a short circuit between the negative electrode and the positive electrode, and the thickness is dependent on the target battery design. , 8 μm or less is more preferable, and 5 μm or less is further preferable. The thickness of the dense layer is more preferably 0.5 μm or more, still more preferably 1 μm or more. The perovskite structure lithium lanthanum titanate has an orthorhombic or tetragonal structure represented by La 2/3-x Li 3x TiO 3 (where x is a number of 0.03 or more and 0.17 or less). It is preferably a crystalline compound. The second layer may further include a porous layer containing lithium lanthanum titanate having a perovskite structure formed on the dense layer. The porous layer may be, for example, a layer filled with the positive electrode active material. This makes it possible to conduct Li more favorably. Alternatively, the positive electrode active material layer may be formed on this porous layer. The thickness of the porous layer may be, for example, 1 μm or more and 100 μm or less, or 50 μm or less. Alternatively, the second layer may not include the porous layer, and the positive electrode active material layer may be formed on the dense layer. The term "dense layer" refers to a layer in which the ratio of the area of pores to the area of the entire dense layer when viewed in cross section is 5% or less. The term "porous layer" refers to a layer in which the area ratio of pores is larger than that of the dense layer, and for example, the ratio of the area of pores to the area of the entire porous layer when viewed in cross section is 20%. It may be the above.
第２層の緻密層は、チタン源、ランタン源の原料に加え第１層に含まれるリチウムをも原料としてチタン酸リチウムランタンが形成されているものとしてもよい。第２層は、その原料としてリチウム源が加えられているものとしても、加えられていないものとしてもよいが、その原料にリチウム源が加えられていないことがより好ましい。こうすれば、第１層に含まれるリチウムが第２層に拡散することにより、第１層と第２層との密着性をより向上することができる。なお、第２層の原料にリチウム源を加える場合においても、第２層の所望の厚さにより決定すればよく、チタン酸リチウムランタンの理論組成よりも少ない量のリチウムを加えるものとすればよい。 The dense layer of the second layer may be one in which lithium lanthanum titanate is formed using the lithium contained in the first layer as a raw material in addition to the raw materials of the titanium source and the lanthanum source. The second layer may or may not have a lithium source added as its raw material, but it is more preferable that the lithium source is not added to the raw material. By so doing, the lithium contained in the first layer diffuses into the second layer, so that the adhesion between the first layer and the second layer can be further improved. Even when a lithium source is added to the raw material of the second layer, it may be determined according to the desired thickness of the second layer, and lithium may be added in an amount smaller than the theoretical composition of lithium lanthanum titanate. ..
本発明の複合体は、全固体型リチウムイオン二次電池に用いることができる。リチウムイオン二次電池は、リチウムイオンを吸蔵・放出しうる正極活物質を有する正極と、リチウムイオンを吸蔵・放出しうる負極活物質を有する負極と、正極と負極との間に介在しリチウムイオンを伝導する固体電解質と、を備えている。正極活物質は、例えば遷移金属とリチウムとを含む複合化合物としてもよい。この複合化合物としては、例えば、遷移金属とリチウムとを含む複合酸化物や、遷移金属とリチウムとを含むリン酸化合物などが挙げられる。複合酸化物としては、例えば、基本組成式をＬｉ(1-x)ＭｎＯ2（０＜ｘ＜１など、以下同じ）やＬｉ(1-x)Ｍｎ2Ｏ4などとするリチウムマンガン複合酸化物、基本組成式をＬｉ(1-x)ＣｏＯ2などとするリチウムコバルト複合酸化物、基本組成式をＬｉ(1-x)ＮｉＯ2などとするリチウムニッケル複合酸化物、基本組成式をＬｉ(1-x)ＭｎaＮｉbＣｏcＯ2（ａ＋ｂ＋ｃ＝１）などとするリチウムマンガンニッケルコバルト複合酸化物などが挙げられる。また、リン酸化合物としては、基本組成式をＬｉＦｅＰＯ4などとするリチウムリン酸鉄化合物が挙げられる。なお、「基本組成式」とは、他の元素を含んでもよい趣旨である。 The composite of the present invention can be used for an all-solid-state lithium ion secondary battery. A lithium-ion secondary battery includes a positive electrode having a positive electrode active material capable of absorbing and releasing lithium ions, a negative electrode having a negative electrode active material capable of absorbing and releasing lithium ions, and a lithium ion interposed between the positive electrode and the negative electrode. And a solid electrolyte that conducts. The positive electrode active material may be, for example, a composite compound containing a transition metal and lithium. Examples of this composite compound include a composite oxide containing a transition metal and lithium, a phosphoric acid compound containing a transition metal and lithium, and the like. As the composite oxide, for example, a lithium manganese composite oxide having a basic composition formula of Li (1-x) MnO 2 (0<x<1, etc., the same applies hereinafter), Li (1-x) Mn 2 O 4, etc. , A lithium cobalt composite oxide having a basic composition formula such as Li (1-x) CoO 2 , a lithium nickel composite oxide having a basic composition formula such as Li (1-x) NiO 2 , and a basic composition formula of Li (1 -x) Mn a Ni b Co c O 2 (a+b+c=1) and the like, such as lithium manganese nickel cobalt composite oxide. Examples of the phosphoric acid compound include lithium iron phosphate compounds having a basic composition formula such as LiFePO 4 . The “basic composition formula” means that other elements may be included.
このリチウムイオン二次電池の形状は、特に限定されないが、例えばコイン型、ボタン型、シート型、積層型、円筒型、偏平型、角型などが挙げられる。また、このリチウムイオン二次電池を複数直列に接続して電気自動車用電源としてもよい。電気自動車としては、例えば、電池のみで駆動する電池電気自動車や内燃機関とモータ駆動とを組み合わせたハイブリッド電気自動車、燃料電池で発電する燃料電池自動車等が挙げられる。全固体型リチウムイオン二次電池の構造は、特に限定されないが、例えば、図１に示す構造が挙げられる。図１は、全固体型のリチウムイオン二次電池２０の構成の概略を示す説明図である。このリチウムイオン二次電池２０は、ペロブスカイト構造チタン酸リチウムランタンを含む固体電解質層１０（第２層）と、この固体電解質層１０の片面に形成された正極１２と、この固体電解質層１０のもう片面に形成された負極１４とを有する。このうち、正極１２は、固体電解質層１０に接する正極活物質層１２ａ（正極活物質を含む層）とこの正極活物質層１２ａに接する集電体１２ｂとにより構成されている。負極１４は、固体電解質層１０に接する負極活物質層１４ａ（第１層）とこの負極活物質層１４ａに接する集電体１４ｂとにより構成されている。更に、集電体１２ｂの上に集電体１２ｂ、正極活物質層１２ａ、固体電解質層１０及び負極活物質層１４ａのユニットを積み上げ、積層構造にすることも容易である。 The shape of the lithium ion secondary battery is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, and a square type. Further, a plurality of the lithium ion secondary batteries may be connected in series to form a power source for an electric vehicle. Examples of the electric vehicle include a battery electric vehicle that is driven only by a battery, a hybrid electric vehicle that combines an internal combustion engine and a motor drive, and a fuel cell vehicle that generates power with a fuel cell. The structure of the all-solid-state lithium-ion secondary battery is not particularly limited, and examples thereof include the structure shown in FIG. FIG. 1 is an explanatory diagram showing an outline of the configuration of an all-solid-state lithium ion secondary battery 20. This lithium-ion secondary battery 20 includes a solid electrolyte layer 10 (second layer) containing a perovskite structure lithium lanthanum titanate, a positive electrode 12 formed on one surface of the solid electrolyte layer 10, and a solid electrolyte layer 10 that includes the solid electrolyte layer 10. And a negative electrode 14 formed on one surface. Among them, the positive electrode 12 is composed of a positive electrode active material layer 12a (a layer containing a positive electrode active material) in contact with the solid electrolyte layer 10 and a current collector 12b in contact with the positive electrode active material layer 12a. The negative electrode 14 is composed of a negative electrode active material layer 14a (first layer) in contact with the solid electrolyte layer 10 and a current collector 14b in contact with the negative electrode active material layer 14a. Furthermore, it is easy to stack the current collector 12b, the positive electrode active material layer 12a, the solid electrolyte layer 10 and the negative electrode active material layer 14a on the current collector 12b to form a laminated structure.
次に、本発明の複合体の製造方法について説明する。この製造方法は、（１）原料形成工程と、（２）第２層形成工程とを含む。この製造方法は、上述した複合体を製造するものとしてもよく、第１層が負極活物質層であり、第２層の緻密層が固体電解質層であり、負極／電解質複合体である複合体を製造するものとしてもよい。 Next, a method for producing the composite of the present invention will be described. This manufacturing method includes (1) a raw material forming step and (2) a second layer forming step. This manufacturing method may be one for manufacturing the above-mentioned composite material, and the first layer is the negative electrode active material layer, the second dense layer is the solid electrolyte layer, and the composite material is the negative electrode/electrolyte composite material. May be manufactured.
（１）原料形成工程
この工程では、チタン酸リチウムを含む成形体または焼結体である第１層上にチタン源及びランタン源を含む第２層の原料を形成した原料形成体を作製する。原料の形成は、固相で行うものとしてもよいし、液相で行うものとしてもよい。固相により原料形成を行うと、第２層は、緻密層と多孔質層とを含むものとすることができる。一方、液相で原料形成を行うと、第２層は、緻密層のみを含むものとすることができる。チタン源としては、例えば、酸化チタン（ＴｉＯ2）やチタン酸ランタン（Ｌａ2Ｔｉ2Ｏ7）、チタン酸リチウム（Ｌｉ4Ｔｉ5Ｏ12）などを用いることができる。ランタン源としては、例えば、酸化ランタン（Ｌａ2Ｏ3）やチタン酸ランタンなどを用いることができる。第２層の原料には、リチウム源が加えられているものとしても、加えられていないものとしてもよいが、リチウム源が加えられていないことがより好ましい。こうすれば、第１層に含まれるリチウムが第２層に拡散することにより、第１層と第２層との密着性をより向上することができる。なお、第２層の原料にリチウム源を加える場合においても、チタン酸リチウムランタンの理論組成よりも少ない量のリチウムを加えるものとすればよい。
(1) Raw Material Forming Step In this step, a raw material forming body is produced in which the raw material of the second layer containing the titanium source and the lanthanum source is formed on the first layer which is the molded body or sintered body containing lithium titanate. The raw materials may be formed in a solid phase or in a liquid phase. When the raw material is formed by the solid phase, the second layer can include a dense layer and a porous layer. On the other hand, when the raw material is formed in the liquid phase, the second layer may include only the dense layer. As the titanium source, for example, titanium oxide (TiO 2 ), lanthanum titanate (La 2 Ti 2 O 7 ), lithium titanate (Li 4 Ti 5 O 12 ) or the like can be used. As the lanthanum source, for example, lanthanum oxide (La 2 O 3 ) or lanthanum titanate can be used. The raw material for the second layer may or may not be added with a lithium source, but it is more preferable that the lithium source is not added. By so doing, the lithium contained in the first layer diffuses into the second layer, so that the adhesion between the first layer and the second layer can be further improved. Even when the lithium source is added to the raw material of the second layer, the amount of lithium added may be smaller than the theoretical composition of lithium lanthanum titanate.
この工程では、固相による原料形成において、チタン源及びランタン源を含む第２層の原料であるテープ状前駆体を第１層上に貼り合わせることにより原料形成体を作製するものとしてもよい。また、この工程では、テープ状前駆体を第１層上に圧着する圧着処理、含まれる有機物などを除去する脱脂処理、第１層と第２層の原料とを加圧固定するＣＩＰ処理などを含むものとしてもよい。図２は、第１層原料の成形体上に固相の第２層の原料を形成する説明図である。第１層は、チタン酸リチウムを含む成形体として、例えば、チタン酸リチウムの粉末を成形した成形体としてもよい。第１層の成形体は、ＣＩＰ処理したＣＩＰ成形体や（図２（ａ）〜（ｄ））、チタン酸リチウムの粉末により形成したテープを１枚以上積層した積層成形体としてもよい（図２（ｅ））。第１層が未焼成の成形体であれば、第２層と共焼成することができ、焼成時のエネルギー消費をより抑制することができ好ましい。なお、ＣＩＰ成形体は、表面を研磨したものとしてもよい。第２層の原料を含むテープ状前駆体は、例えば、チタン酸ランタンの板状粒子と酸化チタンの粉末とにより作製するものとしてもよい（図２（ａ））。また、テープ状前駆体は、チタン酸ランタンの板状粒子とこれを粉砕した粒子と酸化チタンの粉末とにより作製するものとしてもよい（図２（ｂ））。また、テープ状前駆体は、仮焼したチタン酸リチウムランタン粉末を主成分とし、副成分としてチタン酸ランタン（板状粒子）、チタン酸リチウム及び酸化チタンを含む粉末により作製するものとしてもよい（図２（ｃ））。また、テープ状前駆体は、チタン酸ランタンの板状粒子と、チタン酸ランタンの粉砕粒子とチタン酸リチウム及び酸化チタンを含む混合粉末により作製するものとしてもよい（図２（ｄ））。テープ状前駆体は、チタン源及びランタン源に、溶媒や可塑剤、結着材などを加えて混合してスラリー又はペーストとし、ドクターブレードなどの周知の方法で作製することができる。また、テープ状前駆体は、ロールプレスなどにより加圧して厚さや密度が調整されるものとしてもよい。テープ状前駆体の厚さは、目的の緻密層の厚さに応じた厚さに形成すればよく、例えば、０．０５μｍ〜１０μｍの範囲とすることが好ましい。脱脂処理は、テープ状前駆体を第１層上に載置し、前駆体の上におもりを載せた状態で行うものとしてもよいし、テープ状前駆体を第１層上に圧着させたのち行うものとしてもよい。また、脱脂処理は、窒素中、３００℃〜６００℃、０．５ｈ〜５ｈの条件で行うものとしてもよい。ＣＩＰ処理は、５０ＭＰａ〜５００ＭＰａの範囲で行うことが好ましい。 In this step, in forming the raw material by the solid phase, the raw material forming body may be produced by bonding the tape-shaped precursor, which is the raw material of the second layer, containing the titanium source and the lanthanum source, onto the first layer. Further, in this step, a pressure-bonding treatment for pressure-bonding the tape-shaped precursor onto the first layer, a degreasing treatment for removing organic substances contained therein, and a CIP treatment for pressure-fixing the raw materials of the first layer and the second layer are performed. It may be included. FIG. 2 is an explanatory view of forming a solid-phase second layer raw material on a first layer raw material compact. The first layer may be a molded body containing lithium titanate, for example, a molded body formed by molding lithium titanate powder. The first layer molded body may be a CIP molded CIP molded body (FIGS. 2A to 2D) or a laminated molded body in which one or more tapes formed of lithium titanate powder are laminated (FIG. 2(e)). If the first layer is a green body, it can be co-fired with the second layer, and energy consumption during firing can be further suppressed, which is preferable. The CIP molded body may have a polished surface. The tape-shaped precursor containing the raw material for the second layer may be prepared, for example, from plate-like particles of lanthanum titanate and titanium oxide powder (FIG. 2A). Further, the tape-shaped precursor may be prepared by using lanthanum titanate plate-like particles, particles obtained by crushing the particles, and titanium oxide powder (FIG. 2(b)). In addition, the tape-shaped precursor may be produced by using a powder containing lanthanum titanate titanate powder calcined as a main component and lanthanum titanate (plate-like particles), lithium titanate and titanium oxide as sub-components ( FIG. 2C). Further, the tape-shaped precursor may be prepared by using plate-like particles of lanthanum titanate, pulverized particles of lanthanum titanate, and a mixed powder containing lithium titanate and titanium oxide (FIG. 2(d)). The tape-shaped precursor can be prepared by adding a solvent, a plasticizer, a binder and the like to a titanium source and a lanthanum source to form a slurry or a paste, and using a known method such as a doctor blade. Further, the tape-shaped precursor may be adjusted in thickness and density by applying pressure with a roll press or the like. The thickness of the tape-shaped precursor may be formed according to the thickness of the desired dense layer, and is preferably in the range of 0.05 μm to 10 μm, for example. The degreasing treatment may be performed by placing the tape-shaped precursor on the first layer and placing the weight on the precursor, or after the tape-shaped precursor is pressure-bonded on the first layer. It may be done. The degreasing treatment may be performed in nitrogen under the conditions of 300°C to 600°C and 0.5h to 5h. The CIP treatment is preferably performed in the range of 50 MPa to 500 MPa.
この工程では、液相による原料形成において、チタン源及びランタン源を含む原料溶液を第１層上に塗布する塗布処理と第１層上の原料溶液を乾燥し有機成分を分解する乾燥熱分解処理とを１回以上行うことにより原料形成体を作製するものとしてもよい。図３は、第１層原料の成形体上に液相の第２層の原料を形成する説明図である。原料溶液は、例えば、チタン源として、チタンイソプロポキシドを用いて作製したＴｉメトキシエトキシドなどが挙げられる。また、ランタン源としてランタンイソプロポキシドを用いて作製したＬａメトキシエトキシドなどが挙げられる。塗布処理は、例えば、スピンコートなどで行うことができる。乾燥熱分解処理では、乾燥熱分解の温度を１００℃〜５００℃とすることができる。 In this step, in forming a raw material in a liquid phase, a coating treatment for coating a raw material solution containing a titanium source and a lanthanum source on the first layer and a dry pyrolysis treatment for drying the raw material solution on the first layer to decompose organic components. The raw material formed body may be produced by performing the above step once or more. FIG. 3 is an explanatory diagram of forming the liquid-phase second layer raw material on the first-layer raw material compact. Examples of the raw material solution include Ti methoxyethoxide prepared by using titanium isopropoxide as a titanium source. Further, La methoxyethoxide produced by using lanthanum isopropoxide as a lanthanum source can be cited. The coating process can be performed, for example, by spin coating. In the dry pyrolysis treatment, the temperature of the dry pyrolysis can be 100°C to 500°C.
（２）第２層形成工程
この工程では、原料形成体を焼成し第１層に起因するリチウムをも原料として利用して第１層上にペロブスカイト構造のチタン酸リチウムランタンを含む緻密層を少なくとも形成させる。焼成処理は、大気中で８５０℃以上１１００℃未満の範囲で行うことが好ましく、１０００℃以下で行うことがより好ましい。焼成温度は、より低い方がエネルギー消費の観点からみて好ましい。また、焼成処理は、原料成形体をチタン酸リチウムの粉末で覆う、パウダーベッドにより行うことが好ましい。こうすれば、加熱飛散しやすいＬｉの含有量の変化をより抑制することができる。この工程では、第１層の焼成も共に行うことが好ましい。また、この工程では、原料形成体を焼成することにより、緻密層の上にペロブスカイト構造のチタン酸リチウムランタンを含む多孔質層をさらに形成するものとしてもよい。
(2) Second Layer Forming Step In this step, at least a dense layer containing lithium lanthanum titanate having a perovskite structure is formed on the first layer by firing the raw material forming body and also using lithium derived from the first layer as a raw material. Let it form. The firing treatment is preferably performed in the atmosphere at a temperature of 850° C. or higher and lower than 1100° C., more preferably 1000° C. or lower. A lower firing temperature is preferable from the viewpoint of energy consumption. The firing treatment is preferably performed by a powder bed in which the raw material compact is covered with lithium titanate powder. By doing so, it is possible to further suppress the change in the Li content that is easily scattered by heating. In this step, it is preferable to perform the firing of the first layer together. In this step, the raw material forming body may be fired to further form a porous layer containing lithium lanthanum titanate having a perovskite structure on the dense layer.
以上詳述した本実施形態の複合体及びその製造方法では、リチウムイオン伝導性を発揮しつつ、第１層と第２層とをより良好に接合することができる。また、より薄い第２層を形成することができる。すなわち、本発明によれば、固体電解質として高いイオン伝導率であるペロブスカイト構造チタン酸リチウムランタンを負極材料であるチタン酸リチウム上に薄く形成することができ、安全性が高く、かつ、内部抵抗が低い酸化物系の全固体型リチウムイオン二次電池を提供することが可能となる。この理由は、例えば、第１層である負極活物質のチタン酸リチウム上でそれ自身の一部が第２層である電解質合成のためのチタン源、リチウム源となり、層状ペロブスカイト構造のチタン酸ランタン前駆体とその他の原料と反応するためであると推察される。このため、負極活物質上を緻密なペロブスカイト構造のチタン酸リチウムランタンで被覆し、固体電解質と活物質層との固体−固体界面が良好に接合した負極／電解質複合体となるものと推察される。また、本発明では、上述した反応により第２層が形成される際に、その厚みは従来よりもはるかに薄肉化されるものと推察される。このことは、電池全体が薄肉化され内部抵抗の観点で大いに利点になるだけでなく、電極が厚くなる際に必要となる導電助剤などのエネルギー密度を損なう部材を必要としないため、エネルギー密度の向上が図れ、さらに、部材及び製造工程の削減に伴う低コスト化が期待できる。 In the composite body and the manufacturing method thereof according to the present embodiment described in detail above, the first layer and the second layer can be bonded more favorably while exhibiting lithium ion conductivity. Also, a thinner second layer can be formed. That is, according to the present invention, it is possible to form a thin perovskite structure lithium lanthanum titanate having a high ionic conductivity as a solid electrolyte on the lithium titanate which is a negative electrode material, which has high safety and internal resistance. It is possible to provide a low oxide type all-solid-state lithium-ion secondary battery. The reason for this is, for example, lanthanum titanate having a layered perovskite structure, which serves as a titanium source and a lithium source for electrolyte synthesis in which a part of itself is the second layer on the negative electrode active material lithium titanate which is the first layer. It is presumed that this is because it reacts with the precursor and other raw materials. Therefore, it is presumed that the negative electrode/electrolyte composite is obtained by covering the negative electrode active material with lithium lanthanum titanate having a dense perovskite structure, and satisfactorily bonding the solid-solid interface between the solid electrolyte and the active material layer. .. Further, in the present invention, when the second layer is formed by the above-mentioned reaction, the thickness thereof is presumed to be much thinner than the conventional one. This is not only a great advantage from the viewpoint of internal resistance because the entire battery is made thinner, but it does not require a member that impairs the energy density such as a conductive auxiliary agent that is required when the electrode becomes thicker. It can be expected that the cost can be improved by reducing the number of members and manufacturing processes.
なお、本発明は上述した実施形態に何ら限定されることはなく、本発明の技術的範囲に属する限り種々の態様で実施し得ることはいうまでもない。 It is needless to say that the present invention is not limited to the above-described embodiment and can be implemented in various modes within the technical scope of the present invention.
以下には、本発明の複合体（負極／電解質複合体）を具体的に作製した例を実施例として説明する。下記実施例においては、負極活物質層（第１層）を負極支持体とも称し、固体電解質層（第２層）を電解質とも称する。なお、本発明は下記実施例に何ら限定されることはなく、本発明の技術的範囲に属する限り種々の態様で実施し得ることはいうまでもない。 Hereinafter, an example in which the composite of the present invention (negative electrode/electrolyte composite) is specifically prepared will be described as an example. In the following examples, the negative electrode active material layer (first layer) is also referred to as a negative electrode support, and the solid electrolyte layer (second layer) is also referred to as an electrolyte. Needless to say, the present invention is not limited to the following examples and can be carried out in various modes within the technical scope of the present invention.
（負極支持体（ＬｉＴＯ）の作製（ＣＩＰ成形体Ａ１、又は焼結体Ａ２））
市販チタン酸リチウム（Ｌｉ4Ｔｉ5Ｏ12；ＬｉＴＯ，エナマイトＬＴ−１０６石原産業製）をポリエチレンポットに、ジルコニアボール、エタノールと共に入れ、６０時間、ボールミル処理をした。ミル処理後の混合液からエタノールを蒸発させ、ペースト状の試料を回収した。そのペースト状の試料を１１０℃乾燥機中で一晩乾燥させたあと、アルミナ乳鉢で解砕しペレット用試料とした。ペレット金型に目標厚みとなる所定量の市販チタン酸リチウムを充填し、１５０ｋｇｆ／ｃｍ2で１分間保持し、予備成形体を得た。予備成形体をポリエチレン袋に入れ二重に真空パックした後に、３００ＭＰａで１分間保持する条件で冷間等方圧加工処理（ＣＩＰ）を行い、そのＣＩＰ処理したものを回収し負極支持体（ＣＩＰ成形体Ａ１）を得た。また、得られたＣＩＰ成形体を焼成して、負極支持体（焼結体）を作製した。上記負極支持体（ＣＩＰ成形体）の全体を出発原料の市販チタン酸リチウムで覆い焼成を行った。これにより、焼成時における負極支持体（ＣＩＰ成形体）からのリチウム蒸散を抑制することができる。焼成条件は、大気中、昇温速度２００℃／ｈ、１０００℃で４時間保持後とし、冷却は炉冷とした。得られた焼成体表面を研磨し、厚みを整えて負極支持体（焼結体Ａ２）を得た。
(Production of Negative Electrode Support (LiTO) (CIP Molded Body A1 or Sintered Body A2))
Commercially available lithium titanate (Li 4 Ti 5 O 12 ; LiTO, manufactured by Enamito LT-106 Ishihara Sangyo Co., Ltd.) was put in a polyethylene pot together with zirconia balls and ethanol, and ball-milled for 60 hours. Ethanol was evaporated from the mixed solution after the mill treatment, and a paste-like sample was recovered. The paste-like sample was dried overnight in a 110° C. dryer and then crushed in an alumina mortar to give a pellet sample. A pellet mold was filled with a predetermined amount of commercially available lithium titanate having a target thickness and held at 150 kgf/cm 2 for 1 minute to obtain a preform. After placing the preform in a polyethylene bag and double-vacuum packing, cold isostatic processing (CIP) was performed under the condition of holding at 300 MPa for 1 minute, and the CIP-treated product was collected to collect the negative electrode support (CIP). A molded body A1) was obtained. Further, the obtained CIP molded body was fired to prepare a negative electrode support (sintered body). The whole negative electrode support (CIP molded body) was covered with a commercially available lithium titanate as a starting material and fired. This makes it possible to suppress lithium evaporation from the negative electrode support (CIP molded body) during firing. The firing conditions were that the temperature was raised at 200° C./h and the temperature was maintained at 1000° C. for 4 hours in the air, and the furnace was cooled. The surface of the obtained fired body was polished and adjusted in thickness to obtain a negative electrode support (sintered body A2).
（負極支持体（ＬｉＴＯ）の作製（テープ体Ｂ））
上記市販チタン酸リチウムをポリエチレンポットに、ジルコニアボール、エタノールと共に入れ、ボールミル粉砕を行った。ミル粉砕後の混合液からエタノールを蒸発させ、ペースト状の試料を回収した。そのペースト状試料を１１０℃乾燥機中で一晩乾燥させたあと、アルミナ乳鉢で解砕しテープ用粉砕粉末とした。このテープ用粉砕粉末に、１５０質量％の有機溶媒予混合液（トルエン＋エタノール＋ポリビニルブチラール（ＰＶＢ））と可塑剤及び混合撹拌用ジルコニアボールを加え、ボールミル混合を行うことでテープ成形用のスラリーを得た。次に、ドクタープレード装置を用いて、得られたスラリーを厚さ７０〜１００μｍのテープ状に成形し、乾燥させ、テープ成形体を得た。更に、得られたテープ成形体を切断し、１０枚重ねて積層テープ成形体Ｂとした。
(Preparation of Negative Electrode Support (LiTO) (Tape Body B))
The commercially available lithium titanate was placed in a polyethylene pot together with zirconia balls and ethanol and ball-milled. Ethanol was evaporated from the mixed liquid after milling, and a paste sample was collected. The paste-like sample was dried overnight in a 110° C. drier, and then crushed in an alumina mortar to obtain a crushed powder for tape. A slurry for tape molding by adding 150 mass% of an organic solvent premixed liquid (toluene + ethanol + polyvinyl butyral (PVB)), a plasticizer, and zirconia balls for mixing and stirring to the pulverized powder for tape, and performing ball mill mixing. Got Next, using a doctor blade apparatus, the obtained slurry was formed into a tape having a thickness of 70 to 100 μm and dried to obtain a tape formed body. Further, the obtained tape molded body was cut and 10 sheets were stacked to obtain a laminated tape molded body B.
（電解質テープ状前駆体用チタン酸ランタン（板状粒子Ｃ）の合成）
ポットに直径３ｍｍのジルコニアボールとエタノール（和光純薬工業（株）製、特級９９．５％）を入れ、化学量論比でＬａ2Ｔｉ2Ｏ7組成（Ｌａ：Ｔｉ＝１：１（モル））となるように、炭酸ランタン（Ｌａ2（ＣＯ3）3）粉末及び酸化チタン（ＴｉＯ2）粉末（平均粒径０．１５μｍ）を加えて、ボールミリングを行い、混合スラリーを得た。次に、得られた混合スラリーを電気炉中で乾燥し、乾燥した混合粉末を解砕し、この混合粉末に対して、フラックスとして等量の塩化カリウム（ＫＣｌ）を加えて白金るつぼに入れた。次に、白金るつぼを電気炉（粉体合成炉）で加熱し、短冊上の粒子（チタン酸ランタン粉末）を合成した。加熱処理の条件は、１２００℃で８時間保持とした。冷却後に試料のＫＣｌを洗い流し、板状粒子Ｃ（ＬａＴＯ）を得た。
(Synthesis of Lanthanum Titanate (Plate Particle C) for Electrolyte Tape Precursor)
Zirconia balls with a diameter of 3 mm and ethanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade 99.5%) were put in a pot, and a La 2 Ti 2 O 7 composition (La:Ti=1:1 (mol) was obtained in stoichiometric ratio. )), lanthanum carbonate (La 2 (CO 3 ) 3 ) powder and titanium oxide (TiO 2 ) powder (average particle size 0.15 μm) were added, and ball milling was performed to obtain a mixed slurry. Next, the obtained mixed slurry was dried in an electric furnace, the dried mixed powder was crushed, and an equal amount of potassium chloride (KCl) was added as a flux to the mixed powder and put into a platinum crucible. .. Next, the platinum crucible was heated in an electric furnace (powder synthesis furnace) to synthesize strip-shaped particles (lanthanum titanate powder). The heat treatment was performed at 1200° C. for 8 hours. After cooling, KCl of the sample was washed away to obtain plate-like particles C (LaTO).
（電解質テープ状前駆体用チタン酸ランタン（粉砕粒子Ｄ）の合成）
ポットに直径３ｍｍのジルコニアボールとエタノール（和光純薬工業（株）製、特級９９．５％）を入れ、チタン酸ランタン（Ｌａ2Ｔｉ2Ｏ7）を加えて、ボールミル粉砕を行った。ミル粉砕後の混合液からエタノールを蒸発させ、ペースト状の試料を回収した。ペースト状試料を１１０℃乾燥機中で一晩乾燥させたあと、アルミナ乳鉢で解砕しチタン酸ランタン粉砕粒子Ｄ（ＬａＴＯ粉砕粒子）を得た。
(Synthesis of lanthanum titanate (ground particles D) for electrolyte tape precursor)
Zirconia balls with a diameter of 3 mm and ethanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade 99.5%) were placed in a pot, lanthanum titanate (La 2 Ti 2 O 7 ) was added, and ball milling was performed. Ethanol was evaporated from the mixed liquid after milling, and a paste sample was collected. The paste sample was dried overnight in a 110° C. dryer and then crushed in an alumina mortar to obtain lanthanum titanate crushed particles D (LaTO crushed particles).
（板状粒子を含まないチタン酸リチウムランタン（仮焼粉末Ｅ）の合成）
ポットに直径３ｍｍのジルコニアボールとエタノール（和光純薬工業（株）製、特級９９．５％）を入れ、予めボールミルで粉砕したチタン酸リチウム（Ｌｉ4Ｔｉ5Ｏ12）、酸化チタン（ＴｉＯ2）及びチタン酸ランタン（Ｌａ2Ｔｉ2Ｏ7）を配合し、ボールミル混合を行い混合スラリーを得た。混合スラリーよりエタノールを蒸発させたあと、大気中で１０００℃、４時間（昇降温速度２００℃／ｈ）で仮焼して仮焼粉末Ｅを得た。
(Synthesis of lithium lanthanum titanate (calcined powder E) containing no plate-like particles)
Zirconia balls with a diameter of 3 mm and ethanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade 99.5%) were put in a pot, and lithium titanate (Li 4 Ti 5 O 12 ) and titanium oxide (TiO 2 ) were previously crushed with a ball mill. ) And lanthanum titanate (La 2 Ti 2 O 7 ) were mixed, and ball mill mixing was performed to obtain a mixed slurry. After ethanol was evaporated from the mixed slurry, it was calcined in the atmosphere at 1000° C. for 4 hours (temperature rising/falling rate 200° C./h) to obtain a calcined powder E.
（板状粒子を含まないチタン酸リチウムランタン用原料（混合粉末Ｆ）の調整）
ポットに直径３ｍｍのジルコニアボールとエタノール（和光純薬工業（株）製、特級９９．５％）を入れ、チタン酸リチウム（Ｌｉ4Ｔｉ5Ｏ12）、酸化チタン（ＴｉＯ2）及びチタン酸ランタン（Ｌａ2Ｔｉ2Ｏ7）をＬａ0.62Ｌｉ0.16ＴｉＯ3となる比で配合し、ボールミル混合を行い混合スラリーを得た。混合スラリーよりエタノールを蒸発させたあと、アルミナ乳鉢で解砕しチタン酸リチウムランタン原料の混合粉末Ｆを得た。
(Preparation of raw material for lithium lanthanum titanate (mixed powder F) containing no plate-like particles)
Zirconia balls with a diameter of 3 mm and ethanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade 99.5%) were placed in a pot, and lithium titanate (Li 4 Ti 5 O 12 ), titanium oxide (TiO 2 ) and lanthanum titanate were placed. (La 2 Ti 2 O 7 ) was blended in a ratio of La 0.62 Li 0.16 TiO 3 and ball mill mixing was performed to obtain a mixed slurry. After evaporating ethanol from the mixed slurry, it was crushed in an alumina mortar to obtain a mixed powder F of lithium lanthanum titanate raw material.
（電解質テープ状前駆体Ｇ：ＬａＴＯ板状粒子と酸化チタン（ＴｉＯ2）との混合体）
板状粒子Ｃ（ＬａＴＯ）とＴｉＯ2粉末とを、これらが負極支持体ＬｉＴＯと反応してＬａ0.62Ｌｉ0.16ＴｉＯ3となる比で混合したテープ成形用のスラリーを作製した。上記二種類の粉末に、１５０質量％の有機溶媒予混合液（トルエン＋エタノール＋ＰＶＢ）と可塑剤及び混合撹拌用ジルコニアボールを加え、ボールミル混合を行うことでテープ状前駆体用のスラリーを得た。次に、ドクターブレード装置を用いて、得られたスラリーを厚さ７０〜１００μｍのテープ状に成形し、乾燥させ、テープ成形体を得た。更に、得られたテープ成形体を切断し、ロールプレスで厚さＴ＝３０μｍへ調厚した電解質テープ状前駆体Ｇを得た。なお、以後述べるテープ状前駆体に関してもその調厚値は電池設計の重要な設計パラメータであり、また、得ようとする緻密な電解質膜と多孔な電解質膜との比で任意に変更可能である。本実施例では、薄く緻密な電解質膜を有し、かつ、正極材料をその体積と同等以上の電解質多孔層に含浸する構造を選択したので、ロールプレス厚をＴ＝３０μｍに設定した。
(Electrolyte tape-like precursor G: mixture of LaTO plate-like particles and titanium oxide (TiO 2 ))
A slurry for tape molding was prepared by mixing plate-like particles C (LaTO) and TiO 2 powder in a ratio such that they react with the negative electrode support LiTO to become La 0.62 Li 0.16 TiO 3 . A slurry for a tape-shaped precursor was obtained by adding 150% by mass of an organic solvent premixed liquid (toluene+ethanol+PVB), a plasticizer and zirconia balls for mixing and stirring to the above-mentioned two kinds of powders and performing ball mill mixing. .. Next, the obtained slurry was formed into a tape having a thickness of 70 to 100 μm using a doctor blade device and dried to obtain a tape formed body. Further, the obtained tape molded body was cut, and an electrolyte tape-shaped precursor G having a thickness T=30 μm adjusted by a roll press was obtained. The thickness adjustment value of the tape-shaped precursor described below is an important design parameter for battery design, and can be arbitrarily changed depending on the ratio of the dense electrolyte membrane and the porous electrolyte membrane to be obtained. .. In this example, a structure having a thin and dense electrolyte membrane and impregnating the positive electrode material into the electrolyte porous layer having a volume equal to or larger than the volume thereof was selected, so the roll press thickness was set to T=30 μm.
（電解質テープ状前駆体Ｈ：ＬａＴＯ板状粒子とＬａＴＯ粉砕粒子と酸化チタンＴｉＯ2との混合体）
板状粒子Ｃと粉砕粒子Ｄとの二種類のチタン酸ランタンを５：９５（モル比）の割合で混合し、さらにＴｉＯ2粉末を、これらが負極支持体ＬｉＴＯと反応してＬａ0.62Ｌｉ0.16ＴｉＯ3となる比で混合し、電解質テープ状前駆体用のスラリーを作製した。上記三種類の粉末に、１５０質量％の有機溶媒予混合液（トルエン＋エタノール＋ＰＶＢ）と可塑剤及び混合撹拌用ジルコニアボールを加えボールミル混合を行うことでテープ状前駆体用のスラリーを得た。次に、ドクターブレード装置を用いて、得られたスラリーを厚さ７０〜１００μｍのテープ状に成形し、乾燥させ、テープ成形体を得た。更に、得られたテープ成形体を切断し、ロールプレスで厚さＴ＝１５μｍへ調厚した電解質テープ状前駆体Ｈを得た。
(Electrolyte tape-shaped precursor H: mixture of LaTO plate-shaped particles, LaTO ground particles, and titanium oxide TiO 2 )
Two types of lanthanum titanate, plate-like particles C and crushed particles D, were mixed at a ratio of 5:95 (molar ratio), and TiO 2 powder was further reacted with the negative electrode support LiTO to produce La 0.62 Li 0.16. The mixture was mixed at a ratio of TiO 3 to prepare a slurry for the electrolyte tape precursor. A slurry for a tape-shaped precursor was obtained by adding 150% by mass of an organic solvent premixed liquid (toluene+ethanol+PVB), a plasticizer, and zirconia balls for mixing and stirring to the above three kinds of powders and performing ball mill mixing. Next, the obtained slurry was formed into a tape having a thickness of 70 to 100 μm using a doctor blade device and dried to obtain a tape formed body. Further, the obtained tape molded body was cut, and an electrolyte tape-shaped precursor H having a thickness T=15 μm adjusted by a roll press was obtained.
（電解質テープ状前駆体Ｉ：チタン酸リチウムランタン（仮焼粉末Ｅ））
チタン酸リチウムランタン粉末（仮焼粉末Ｅ）９５モル％に対して、反応すれば５モル％のチタン酸リチウムランタンとなる、板状粒子Ｃ（ＬａＴＯ）、Ｌｉ4Ｔｉ5Ｏ12粒子、ＴｉＯ2粒子を加え、これに１５０質量％の有機溶媒予混合液（トルエン＋エタノール＋ＰＶＢ）と可塑剤及び混合撹拌用ジルコニアボールを加えボールミル混合を行うことでテープ成形用のスラリーを得た。次に、ドクターブレード装置を用いて、得られたスラリーを厚さ７０〜１００μｍのテープ状に成形し、乾燥させ、テープ成形体を得た。更に、得られたテープ成形体を切断し、ロールプレスで厚さＴ＝５０μｍへ調厚した電解質テープ状前駆体Ｉを得た。
(Electrolyte tape-shaped precursor I: lithium lanthanum titanate (calcined powder E))
Plate-like particles C (LaTO), Li 4 Ti 5 O 12 particles, and TiO 2 which become 5 mol% of lithium lanthanum titanate when reacted with 95 mol% of lithium lanthanum titanate powder (calcined powder E) Particles were added, and a 150% by mass organic solvent premixed solution (toluene+ethanol+PVB), a plasticizer, and zirconia balls for mixing and stirring were added, and ball mill mixing was performed to obtain a slurry for tape molding. Next, the obtained slurry was formed into a tape having a thickness of 70 to 100 μm using a doctor blade device and dried to obtain a tape formed body. Further, the obtained tape molded body was cut, and an electrolyte tape-shaped precursor I whose thickness was adjusted to T=50 μm by a roll press was obtained.
（電解質テープ状前駆体Ｊ：チタン酸リチウムランタン用原料混合粉末）
板状粒子Ｃと粉砕粒子Ｄとの二種類のチタン酸ランタンを５：９５（モル比）の割合になり、且つそれと反応してチタン酸リチウムランタンが合成される比のＬｉ4Ｔｉ5Ｏ12粒子とＴｉＯ2粒子とから成るチタン酸リチウムランタン用粉末（混合粉末）に、１５０質量％の有機溶媒予混合液（トルエン＋エタノール＋ＰＶＢ）と可塑剤及び混合撹拌用ジルコニアボールを加えボールミル混合を行うことでテープ成形用のスラリーを得た。次に、ドクターブレード装置を用いて、得られたスラリーを厚さ７０〜１００μｍのテープ状に成形し、乾燥させ、テープ成形体を得た。更に、得られたテープ成形体を切断し、ロールプレスで厚さＴ＝５０μｍへ調厚した電解質テープ状前駆体Ｊを得た。
(Electrolyte tape-shaped precursor J: Raw material mixed powder for lithium lanthanum titanate)
Two types of lanthanum titanate, the plate-like particles C and the crushed particles D, have a ratio of 5:95 (molar ratio), and a ratio of Li 4 Ti 5 O 12 which is reacted with the lanthanum titanate to synthesize lithium lanthanum titanate. To a powder of lithium lanthanum titanate composed of particles and TiO 2 particles (mixed powder), 150% by mass of an organic solvent premixed liquid (toluene+ethanol+PVB), a plasticizer, and a zirconia ball for mixing and stirring are added and ball-milled. Thus, a slurry for tape molding was obtained. Next, the obtained slurry was formed into a tape having a thickness of 70 to 100 μm using a doctor blade device and dried to obtain a tape formed body. Further, the obtained tape molded body was cut, and an electrolyte tape-shaped precursor J having a thickness T=50 μm adjusted by a roll press was obtained.
（固相による負極（ＬｉＴＯ）／電解質（ＬＬＴＯ）複合体（実施例１）の作製）
負極支持体（ＣＩＰ成形体Ａ１、第１層の原料）上に電解質テープ状前駆体Ｇ（第２層の原料）を載せて、窒素中５００℃、１ｈで脱脂したあと、３００ＭＰａでＣＩＰ処理を行った。さらに、負極支持体の下側及び周囲に、市販チタン酸リチウム粉末を配置したあと、１０００℃で４ｈ焼成し、第１層を負極活物質層とし第２層を固体電解質層とする実施例１の負極／電解質複合体を得た（図２（ａ）参照）。
(Preparation of negative electrode (LiTO)/electrolyte (LLTO) composite (Example 1) by solid phase)
The electrolyte tape precursor G (raw material for the second layer) was placed on the negative electrode support (CIP molded body A1, raw material for the first layer), degreased in nitrogen at 500° C. for 1 hour, and then subjected to CIP treatment at 300 MPa. went. Further, after placing a commercially available lithium titanate powder on the lower side and the periphery of the negative electrode support, it was baked at 1000° C. for 4 hours, and the first layer was the negative electrode active material layer and the second layer was the solid electrolyte layer. A negative electrode/electrolyte composite of was obtained (see FIG. 2(a)).
（固相による負極／電解質複合体（実施例２）の作製）
負極支持体（ＣＩＰ成形体Ａ１の研磨品、第１層の原料）上に電解質テープ状前駆体Ｈを載せ、窒素中５００℃、１ｈで脱脂したあと、２５０ＭＰａでＣＩＰ処理を行った。さらに、負極支持体の下側及び周囲に市販チタン酸リチウム粉末を配置したあと、１０００℃、４ｈ焼成し、実施例２の負極／電解質複合体を得た（図２（ｂ）参照）。
(Preparation of negative electrode/electrolyte complex (Example 2) by solid phase)
The electrolyte tape precursor H was placed on the negative electrode support (the polished product of the CIP molded product A1, the raw material for the first layer), degreased in nitrogen at 500° C. for 1 hour, and then subjected to CIP treatment at 250 MPa. Further, after placing a commercially available lithium titanate powder on the lower side and the periphery of the negative electrode support, it was baked at 1000° C. for 4 hours to obtain a negative electrode/electrolyte composite of Example 2 (see FIG. 2(b)).
（固相による負極／電解質複合体（実施例３）の作製）
負極支持体（ＣＩＰ成形体Ａ１の研磨品、第１層の原料）上に電解質テープ状前駆体Ｉを載せ、窒素中５００℃、１ｈで脱脂したあと、２５０ＭＰａでＣＩＰ処理を行った。さらに、負極支持体の下側及び周囲に市販チタン酸リチウム粉末を配置したあと、１０００℃、４ｈ焼成し、実施例３の負極／電解質複合体を得た（図２（ｃ）参照）。
(Preparation of Negative Electrolyte/Electrolyte Complex (Example 3) by Solid Phase)
The electrolyte tape precursor I was placed on the negative electrode support (the polished product of the CIP molded product A1, the raw material for the first layer), degreased in nitrogen at 500° C. for 1 hour, and then subjected to CIP treatment at 250 MPa. Further, after placing a commercially available lithium titanate powder on the lower side and the periphery of the negative electrode support, it was baked at 1000° C. for 4 hours to obtain a negative electrode/electrolyte composite of Example 3 (see FIG. 2(c)).
（固相による負極／電解質複合体（実施例４）の作製）
負極支持体（ＣＩＰ成形体Ａ１の研磨品、第１層の原料）上に電解質テープ状前駆体Ｊを載せ、窒素中５００℃、１ｈで脱脂したあと、２５０ＭＰａでＣＩＰ処理を行った。さらに、負極支持体の下側及び周囲に市販チタン酸リチウム粉末を配置したあと、１０００℃、４ｈ焼成し、実施例４の負極／電解質複合体を得た（図２（ｄ）参照）。また、負極支持体をテープ体Ｂとし、８０℃、５ＭＰａで圧着した試料も同様に、脱脂、ＣＩＰ処理、焼成した（図２（ｅ）参照）。
(Preparation of negative electrode/electrolyte complex (Example 4) by solid phase)
The electrolyte tape precursor J was placed on the negative electrode support (polished product of CIP molded product A1, raw material for the first layer), degreased in nitrogen at 500° C. for 1 hour, and then subjected to CIP treatment at 250 MPa. Further, after placing a commercially available lithium titanate powder on the lower side and the periphery of the negative electrode support, it was baked at 1000° C. for 4 hours to obtain a negative electrode/electrolyte composite of Example 4 (see FIG. 2(d)). In addition, a sample pressed with the tape support B as the negative electrode support at 80° C. and 5 MPa was similarly degreased, CIP-treated, and baked (see FIG. 2E).
（表面ＸＲＤ分析）
作製した負極／電解質複合体（実施例１〜４）の表面をＸＲＤ測定した。ＸＲＤ測定は、ＸＲＤ測定器（リガク製、ＵＬｔｉｍａ ＩＶ）を用いて、ＣｕＫα線を用い、印加電圧を４０ｋＶ、電流４０ｍＡに設定し、２θ＝１０〜９０°、１０°／分の条件で測定した。
(Surface XRD analysis)
The surface of the prepared negative electrode/electrolyte composite (Examples 1 to 4) was measured by XRD. The XRD measurement was performed under the conditions of 2θ=10 to 90° and 10°/min using an XRD measuring device (manufactured by Rigaku, ULtima IV), using CuKα rays, setting an applied voltage to 40 kV and a current of 40 mA. ..
（走査型電子顕微鏡（ＳＥＭ）観察）
作製した負極／電解質複合体１〜４の断面をＳＥＭ観察した。ＳＥＭ観察は、日立ハイテクノロジーズ社製Ｓ−３６００Ｎ及びＳ−４３００を用いて１０００〜１００００倍の条件で行った。
(Scanning electron microscope (SEM) observation)
The cross sections of the produced negative electrode/electrolyte composites 1 to 4 were observed by SEM. The SEM observation was performed under the conditions of 1000 to 10000 times using S-3600N and S-4300 manufactured by Hitachi High Technologies.
（固相による負極／電解質複合体（実施例１〜４）の特性）
図４は、固相により作製した実施例１の負極／電解質複合体１の電解質側表面に対するＸＲＤ測定結果である。図５は、固相により作製した実施例１の負極／電解質複合体の断面ＳＥＭ写真である。図６は、固相により作製した実施例２の負極／電解質複合体の電解質側表面に対するＸＲＤ測定結果である。図７は、固相により作製した実施例２の負極／電解質複合体の断面ＳＥＭ写真である。図８は、固相により作製した実施例３の負極／電解質複合体の電解質側表面に対するＸＲＤ測定結果である。図９は、固相により作製した実施例３の負極／電解質複合体の断面ＳＥＭ写真である。図１０は、固相により作製した実施例４の負極／電解質複合体の電解質側表面に対するＸＲＤ測定結果である。図１１は、固相により作製した実施例４の負極／電解質複合体の断面ＳＥＭ写真である。各ＳＥＭ写真には、反射電子像と二次電子像とを示し、任意位置の拡大写真も適宜示した。図４、６、８、１０に示す様に、実施例１〜４では、チタン酸リチウムランタン（Ｌｉ0.16Ｌａ0.62ＴｉＯ3）の電解質層が検出された。また、図５、７、９、１１に示す様に、負極支持体（基材）であるチタン酸リチウム上には、チタン酸リチウムランタンの緻密層が被覆しており、この緻密層の上に多孔質層が形成されていることがわかった。実施例１、２においては、電解質層の原料にリチウム源はないことから、負極支持体のリチウムが第２層へ拡散したものと推察された。また、負極支持体と固体電解質との間の界面に抵抗層のような物質は確認されなかった。したがって、これらの複合体では、リチウム伝導性が好適であるものと推察された。実施例１〜４の作製方法によれば、負極／電解質複合体の接合性をより向上することができることがわかった。また、緻密層を固体電解質層とすれば、その厚さは１μｍ〜２μｍ程度であり、極薄の固体電解質層を形成することができることもわかった。また、負極支持体をＣＩＰ体（Ａ１）からテープ成形体Ｂに変えても、結果は変わらなかった。
(Characteristics of solid phase negative electrode/electrolyte composite (Examples 1 to 4))
FIG. 4 shows the XRD measurement results for the electrolyte-side surface of the negative electrode/electrolyte composite 1 of Example 1 produced by solid phase. FIG. 5 is a cross-sectional SEM photograph of the negative electrode/electrolyte composite of Example 1 produced by solid phase. FIG. 6 shows the XRD measurement results for the electrolyte-side surface of the negative electrode/electrolyte composite of Example 2 produced by solid phase. FIG. 7 is a cross-sectional SEM photograph of the negative electrode/electrolyte composite of Example 2 produced by solid phase. FIG. 8 shows the XRD measurement results for the electrolyte-side surface of the negative electrode/electrolyte composite of Example 3 produced by solid phase. FIG. 9 is a cross-sectional SEM photograph of the negative electrode/electrolyte composite of Example 3 produced by solid phase. FIG. 10 shows the XRD measurement results for the electrolyte-side surface of the negative electrode/electrolyte composite of Example 4 produced by solid phase. FIG. 11 is a cross-sectional SEM photograph of the negative electrode/electrolyte composite of Example 4 produced by the solid phase. A backscattered electron image and a secondary electron image are shown in each SEM photograph, and an enlarged photograph at an arbitrary position is also appropriately shown. As shown in FIGS. 4, 6, 8 and 10, in Examples 1 to 4, an electrolyte layer of lithium lanthanum titanate (Li 0.16 La 0.62 TiO 3 ) was detected. Further, as shown in FIGS. 5, 7, 9, and 11, lithium titanate, which is a negative electrode support (base material), is covered with a dense layer of lithium lanthanum titanate. It was found that a porous layer was formed. In Examples 1 and 2, since there was no lithium source in the raw material of the electrolyte layer, it was speculated that the lithium of the negative electrode support diffused into the second layer. In addition, no substance such as a resistance layer was observed at the interface between the negative electrode support and the solid electrolyte. Therefore, it was speculated that lithium conductivity was suitable for these composites. It was found that according to the manufacturing methods of Examples 1 to 4, the bondability of the negative electrode/electrolyte composite can be further improved. It was also found that if the dense layer is a solid electrolyte layer, the thickness is about 1 μm to 2 μm, and an extremely thin solid electrolyte layer can be formed. Moreover, the result did not change even when the negative electrode support was changed from the CIP body (A1) to the tape molded body B.
次に、液相による負極／電解質複合体を作製した例について説明する。 Next, an example of producing a liquid phase negative electrode/electrolyte composite will be described.
（塗布溶液の作製）
窒素雰囲気中にてチタンイソプロポキシドとランタンイソプロポキシドをモル比がおよそ１：１．３０５となるように、それぞれ３．７２４ｇ、３．１７ｇをメトキシエタノール１０ｍＬに溶解させて混合溶液を作製した。上記の溶液を１１８℃で３ｈ攪拌還流したあと、１２０〜１２３℃で溶媒を３ｈ減圧蒸発させた。その後、メトキシエタノール１０ｍＬを加えて上記の操作を繰り返し、配位子を置換した。得られたＬａメトキシエトキシド（Ｌａ（ＯＥＭ）3）、Ｔｉメトキシエトキシド（Ｔｉ（ＯＥＭ）4）の混合溶液を希釈して０．１ＭのＬａ（ＯＥＭ）3、０．１３０５ＭのＴｉ（ＯＥＭ）4の塗布溶液を作製した。
(Preparation of coating solution)
In a nitrogen atmosphere, 3.724 g and 3.17 g of titanium isopropoxide and lanthanum isopropoxide were dissolved in 10 mL of methoxyethanol to prepare a mixed solution so that the molar ratio was about 1:1.305. .. The above solution was stirred and refluxed at 118° C. for 3 hours, and then the solvent was evaporated under reduced pressure at 120 to 123° C. for 3 hours. Then, 10 mL of methoxyethanol was added and the above operation was repeated to replace the ligand. The obtained mixed solution of La methoxyethoxide (La(OEM) 3 ) and Ti methoxyethoxide (Ti(OEM) 4 ) was diluted to obtain 0.1M La(OEM) 3 and 0.1305M Ti(OEM). 4 ) A coating solution of 4 was prepared.
（液相による負極／電解質複合体（実施例５）の作製）
ＣＩＰ成形体Ａ１（チタン酸リチウム成形体）に上記の塗布溶液をスピンコートにて塗布した。チタン酸リチウム成形体を２０００ｒｐｍ−２０ｓで回転させながら２ｍＬの注射器を用いて塗布溶液１０滴を滴下してＬａ（ＯＥＭ）3、Ｔｉ（ＯＥＭ）4を塗布した。塗布後にチタン酸リチウム成形体の温度を３００℃、４５０℃の順に各１分加熱してＬａ（ＯＥＭ）3、Ｔｉ（ＯＥＭ）4を熱分解させ、３００℃、室温の順にそれぞれ１分、２分静置して冷却した。上記の操作を２０回繰り返して前駆体薄膜をチタン酸リチウム成形体上に作製した。得られたチタン酸リチウムランタン前駆体薄膜／チタン酸リチウム成形体を空気中９５０℃、１ｈ焼成して実施例５の負極／電解質接合体（ＬＬＴＯ／ＬｉＴＯ構造体）を得た。なお、チタン酸リチウムランタンの膜厚に関しては固相式と同様、電池設計の重要な設計パラメータであり、主にスピンコートの繰り返し回数で当然任意に制御可能である。本実施例では、１μｍのチタン酸リチウムランタン薄膜をチタン酸リチウム成形体上に形成するものとし、スピンコート繰り返し回数は２０回とした。
(Production of Negative Electrode/Electrolyte Complex (Example 5) by Liquid Phase)
The above coating solution was applied to the CIP molded product A1 (lithium titanate molded product) by spin coating. La(OEM) 3 and Ti(OEM) 4 were applied by dropping 10 drops of the coating solution using a 2 mL syringe while rotating the lithium titanate molded body at 2000 rpm-20 s. After coating, the temperature of the lithium titanate molded body is heated in the order of 300° C. and 450° C. for 1 minute each to cause La(OEM) 3 and Ti(OEM) 4 to be thermally decomposed, and 300° C. and room temperature in this order for 1 minute and 2 respectively. It was left to stand for cooling. The above operation was repeated 20 times to prepare a precursor thin film on the lithium titanate molded body. The obtained lithium lanthanum titanate precursor thin film/lithium titanate molded body was fired in air at 950° C. for 1 hour to obtain a negative electrode/electrolyte junction body (LLTO/LiTO structure) of Example 5. The film thickness of lithium lanthanum titanate is an important design parameter for battery design, as in the solid-phase method, and can be naturally controlled mainly by the number of times of spin coating. In this example, a 1 μm thick lithium lanthanum titanate thin film was formed on a lithium titanate molded body, and the spin coating was repeated 20 times.
（固相による負極／電解質接合体の作製：比較例１〜３）
電解質テープ状前駆体用に調整した板状粒子を含まないチタン酸リチウムランタン（仮焼粉末Ｅ）を、目標厚みとする所定量充填し、１５０ｋｇｆ／ｃｍ2で１分間保持し、予備成形体を得た。予備成形体をポリエチレン袋に入れ二重に真空パックした後に、３００ＭＰａで１分間保持する条件でＣＩＰ処理したものをＣＩＰ処理済み焼成前電解質試料とした。負極支持体（ＣＩＰ成形体Ａ１）上に上記ＣＩＰ処理済み焼成前電解質試料を載せ、負極支持体の下側及び周囲に市販チタン酸リチウム粉末を配置したあと、１０００℃、６ｈ焼成し、比較例１の負極／電解質接合体を得た。また、焼成温度を１１００℃とした以外は、比較例１と同様の工程を経て得られた負極／電解質接合体を比較例２とした。また、焼成温度を１２００℃とした以外は、比較例１と同様の工程を経て得られた負極／電解質接合体を比較例３とした。
(Preparation of Negative Electrode/Electrolyte Bonded Body by Solid Phase: Comparative Examples 1 to 3)
Lithium lanthanum titanate (calcined powder E) containing no plate-like particles prepared for the electrolyte tape precursor was charged in a predetermined amount as a target thickness and held at 150 kgf/cm 2 for 1 minute to prepare a preform. Obtained. The preform was put into a polyethylene bag, double-vacuum-packed, and then CIP-treated under the condition of holding at 300 MPa for 1 minute to obtain a CIP-treated pre-firing electrolyte sample. The above CIP-treated pre-fired electrolyte sample was placed on the negative electrode support (CIP molded body A1), and commercially available lithium titanate powder was placed under and around the negative electrode support, followed by firing at 1000° C. for 6 hours, and a comparative example. A negative electrode/electrolyte assembly 1 was obtained. In addition, a negative electrode/electrolyte assembly obtained through the same steps as in Comparative Example 1 was used as Comparative Example 2 except that the firing temperature was set to 1100°C. In addition, a negative electrode/electrolyte assembly obtained through the same steps as in Comparative Example 1 was set as Comparative Example 3 except that the firing temperature was 1200°C.
（負極／電解質複合体（実施例５、比較例１〜３）の特性）
図１２は、液相により作製した実施例５の負極／電解質複合体のＸＲＤ測定結果である。図１３は、液相により作製した実施例５の負極／電解質複合体のＳＥＭ写真である。図１４は、固相により作製した比較例２、３の負極／電解質複合体のＸＲＤ測定結果である。図１２、１３に示す様に、液相で第２層（電解質層）を形成した実施例５においても、固相で第２層を形成した実施例１〜４と同様に、チタン酸リチウムランタンの緻密層が形成されていることがわかった。電解質層の原料にリチウム源はないことから、負極支持体のリチウムが第２層へ拡散したものと推察された。比較例１〜３では、いずれの条件でも、チタン酸リチウムランタン（ＬＬＴＯ）は負極支持体（ＬｉＴＯ）と部分的には接合しているものの、全体が密着した緻密な界面は得られなかった。また、図１４に示す様に、第２層と接していない第１層表面のＸＲＤ測定結果から、比較例２、３に示すように、１０００℃を超える高温では、ＴｉＯ2やＬｉ2Ｔｉ3Ｏ7などが検出されており、負極支持体の分解が進むことがわかった。
(Characteristics of Negative Electrode/Electrolyte Complex (Example 5, Comparative Examples 1 to 3))
FIG. 12 shows the XRD measurement results of the negative electrode/electrolyte composite of Example 5 produced in the liquid phase. FIG. 13 is an SEM photograph of the negative electrode/electrolyte composite of Example 5 produced in the liquid phase. FIG. 14 shows the XRD measurement results of the negative electrode/electrolyte composites of Comparative Examples 2 and 3 produced by solid phase. As shown in FIGS. 12 and 13, in Example 5 in which the second layer (electrolyte layer) was formed in the liquid phase, lithium lanthanum titanate was used as in Examples 1 to 4 in which the second layer was formed in the solid phase. It was found that a dense layer was formed. Since there was no lithium source in the raw material of the electrolyte layer, it was speculated that the lithium of the negative electrode support diffused into the second layer. In Comparative Examples 1 to 3, under all conditions, lithium lanthanum titanate (LLTO) was partially bonded to the negative electrode support (LiTO), but a dense interface where the whole was in close contact was not obtained. Further, as shown in FIG. 14, from the XRD measurement results of the surface of the first layer not in contact with the second layer, as shown in Comparative Examples 2 and 3, at a high temperature exceeding 1000° C., TiO 2 and Li 2 Ti 3 O 7 etc. were detected, and it was found that the decomposition of the negative electrode support proceeded.
（電解質ＬＬＴＯの焼結密度を検討する試料の作製：比較例４〜６）
ポットに直径３ｍｍのジルコニアボールとエタノール（和光純薬工業（株）製、特級９９．５％）を入れ、電解質テープ状前駆体Ｈに用いた粉末（ＬａＴＯとして板状粒子Ｃと粉砕粒子Ｄとを５：９５（モル比）の割合で混合し、さらにＴｉＯ2粉末をこれらが負極支持体ＬｉＴＯと反応してＬａ0.62Ｌｉ0.16ＴｉＯ3となる比で混合した粉末）を加え、ボールミル混合を行い混合スラリーを得た。混合スラリーよりエタノールを蒸発させたあと、アルミナ乳鉢で解砕しチタン酸リチウムランタン原料の混合粉末Ｋを得た。この混合粉末Ｋをペレット金型に目標厚みとする所定量充填し、１５０ｋｇｆ／ｃｍ2で１分間保持し、予備成形体を得た。この予備成形体をポリエチレン袋に入れ、二重に真空パックしたのちに、３００ＭＰａで１分間保持する条件でＣＩＰ処理することによりＣＩＰ体を得た。このＣＩＰ体の下側及び周囲（上側以外）に市販チタン酸リチウム粉末を配置したのち、１１００℃、６時間で焼成し、得られたものを比較例４の電解質焼結体とした。また、焼成温度を１２００℃とした以外、比較例４と同様の工程を経て得られたものを比較例５とした。また、焼成温度を１３５０℃とした以外、比較例４と同様の工程を経て得られたものを比較例６とした。
(Preparation of Sample for Examining Sintered Density of Electrolyte LLTO: Comparative Examples 4 to 6)
Zirconia balls with a diameter of 3 mm and ethanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade 99.5%) were placed in a pot, and powder (plate-like particles C and pulverized particles D as LaTO) used for the electrolyte tape precursor H was placed. Was mixed at a ratio of 5:95 (molar ratio), and TiO 2 powder was further mixed in a ratio such that these react with the negative electrode support LiTO to become La 0.62 Li 0.16 TiO 3 ), and ball mill mixing was performed. A mixed slurry was obtained. After evaporating ethanol from the mixed slurry, the mixture was crushed in an alumina mortar to obtain a mixed powder K of lithium lanthanum titanate raw material. A pellet mold was filled with a predetermined amount of this mixed powder K to a target thickness, and the mixture was held at 150 kgf/cm 2 for 1 minute to obtain a preform. This preform was put in a polyethylene bag, double vacuum-packed, and then CIP-treated under a condition of holding at 300 MPa for 1 minute to obtain a CIP body. Commercially available lithium titanate powder was placed on the lower side and the periphery (other than the upper side) of this CIP body, and the mixture was fired at 1100° C. for 6 hours to obtain an electrolyte sintered body of Comparative Example 4. Further, Comparative Example 5 was obtained through the same steps as Comparative Example 4 except that the firing temperature was 1200°C. Further, Comparative Example 6 was obtained through the same steps as Comparative Example 4 except that the firing temperature was 1350°C.
比較例４〜６の電解質焼結体の相対密度を測定したところ、それぞれ７８．０体積％、９４．０体積％、９８．１体積％であった。この結果より、１１００℃、１２００℃の焼成条件であっても、相対密度が低い焼結体しか得られないことがわかった。このため、比較例４〜６では、イオン伝導度の向上は期待できないことが予想された。 When the relative densities of the electrolyte sintered bodies of Comparative Examples 4 to 6 were measured, they were 78.0% by volume, 94.0% by volume, and 98.1% by volume, respectively. From this result, it was found that only a sintered body having a low relative density could be obtained even under the firing conditions of 1100°C and 1200°C. Therefore, in Comparative Examples 4 to 6, it was expected that no improvement in ionic conductivity could be expected.
上述した特許文献１（特開２０１３−１０５６４６号公報）では、ランタン源の粒子を３００ｎｍ以下とし、チタン源の粒子を５０ｎｍ以下とするなど、ナノ粒子を出発原料とすることでチタン酸リチウムランタンの固体電解質を、７００℃〜９００℃の比較的低温で焼成して形成するものとしている。しかしながら、この固体電解質では、イオン伝導度が低いものも存在しており、十分とはいえなかった。あるいは、特開２００８−５９８４３号公報においては、１１５０℃で１２ｈで焼成したのち１３５０℃で６ｈ成形焼結するなど、高温で処理するものとしている。非特許文献１（NIST Phase Equilibria Diagrams Online Vol.06,Fig.06355-System Li2O-TiO2. Mater.Res.Bull.,15[11]1655-1660(1980)）に示されたチタン酸リチウムの組成と温度との関係を表す相図によれば、チタン酸リチウムは、１０１５℃付近で分解することが明らかである。ここで、特許文献１の表２に示されているように、固体電解質は９００℃など比較的低温で合成できているが、イオン伝導度は、９００℃では不足する場合がある（条件１より）。しかし、第２条件（１１５０℃×１２ｈの仮焼後、１３５０℃×６ｈの本焼成）であれば、比較的良好なイオン伝導度を示す。この低いイオン伝導度は、イオン伝導度を測る供試体（バルク体）の焼結体の密度不足によるものと本発明者は考えた。しかしながら、特許文献１の第２条件で電解質が合成できたとしても、上記相図により、１０１５℃以上でチタン酸リチウムは分解する可能性が高い。したがって、負極活物質（チタン酸リチウム）と固体電解質（チタン酸リチウムランタン）とを共焼成し、良好な界面を形成する条件に第２条件は適さない。固体電解質の単体が合成できてもその後の正極又は負極活物質との組み合わせ時に障害があり得る。 In the above-mentioned Patent Document 1 (JP 2013-105646 A), the particles of the lanthanum source are 300 nm or less and the particles of the titanium source are 50 nm or less. The solid electrolyte is formed by firing at a relatively low temperature of 700°C to 900°C. However, some of these solid electrolytes have low ionic conductivity, which is not sufficient. Alternatively, in Japanese Patent Application Laid-Open No. 2008-59843, the treatment is performed at a high temperature such as firing at 1150° C. for 12 hours and then compacting and sintering at 1350° C. for 6 hours. Non-Patent Document 1 (NIST Phase Equilibria Diagrams Online Vol.06 , Fig.06355-System Li 2 O-TiO 2. Mater.Res.Bull., 15 [11] 1655-1660 (1980)) titanate shown in According to the phase diagram showing the relationship between the composition of lithium and the temperature, it is clear that lithium titanate decomposes at around 1015°C. Here, as shown in Table 2 of Patent Document 1, the solid electrolyte can be synthesized at a relatively low temperature such as 900° C., but the ionic conductivity may be insufficient at 900° C. (from Condition 1) ). However, under the second condition (after calcination at 1150° C.×12 h, main firing at 1350° C.×6 h), relatively good ionic conductivity is exhibited. The present inventor considered that this low ionic conductivity was due to insufficient density of the sintered body of the sample (bulk body) whose ionic conductivity was measured. However, even if the electrolyte can be synthesized under the second condition of Patent Document 1, there is a high possibility that lithium titanate will decompose at 1015° C. or higher according to the above phase diagram. Therefore, the second condition is not suitable for forming a good interface by co-firing the negative electrode active material (lithium titanate) and the solid electrolyte (lithium lanthanum titanate). Even if a simple substance of the solid electrolyte can be synthesized, there may be a problem in the subsequent combination with the positive electrode or the negative electrode active material.
固体電解質の緻密体を必要な部位（例えば活物質全面）に必要な厚み（できるだけ薄肉で）で形成する際に、負極活物質である第１層上でその場で緻密な固体電解質層である第２層を合成することを考えた。この際に必要な要件は、上述のように、第２層（ＬＬＴＯ）の電解質が合成できていること、及び第２層の固体電解質が緻密体であることである。この点において、上述した比較例１〜３では、固体電解質ＬＬＴＯと負極活物質ＬｉＴＯとは部分的に接合しているものの、全体が密着した緻密な界面は得られなかった。また、１０００℃を超えた比較例２、３は、固体電解質ＬＬＴＯと接していない面のＸ線回折測定結果より、負極活物質ＬｉＴＯの分解を示唆するＴｉＯ2やＬｉ2Ｔｉ3Ｏ7が検出された。これは、非特許文献１の相図により支持される結果であった。また、比較例４〜６は、焼成温度ごとにバルク体（ＬＬＴＯ）の焼結密度を比較したものであるが、固体電解質ＬＬＴＯ単体のバルク体焼結密度は、比較例６（１３５０℃焼成）以外では不足していることが確認された。よって、所望のイオン伝導度を示すバルク体単相電解質は、高温焼成した比較例６しか合成できないと推察される。しかし、比較例６の温度条件は比較例３と同様に、目的である固体電解質ＬＬＴＯと負極活物質ＬｉＴＯとの接合体を作成する温度条件には高すぎる。これに対して、本願発明では、原料のナノ粒子化や焼成温度の高温化を行わずに結晶成長の促進及び緻密化を図ることを検討した。そして、本願発明では、活物質である第１層に起因するリチウムをも原料として利用して固体電解質である第２層を形成するものとし、例えば、１１００℃未満の焼成温度において、負極であるチタン酸リチウムと固体電解質であるチタン酸リチウムランタンとが緻密且つ良好な界面で共存したものとすることができたのである。 A dense solid electrolyte layer is formed in situ on the first layer, which is the negative electrode active material, when a dense body of the solid electrolyte is formed in a required portion (for example, the entire surface of the active material) with a required thickness (as thin as possible). Considered synthesizing the second layer. In this case, the necessary requirements are that the electrolyte of the second layer (LLTO) can be synthesized and that the solid electrolyte of the second layer is a dense body, as described above. In this respect, in Comparative Examples 1 to 3 described above, the solid electrolyte LLTO and the negative electrode active material LiTO were partially joined, but a dense interface where the whole was in close contact was not obtained. Further, in Comparative Examples 2 and 3 in which the temperature exceeded 1000° C., TiO 2 and Li 2 Ti 3 O 7 suggesting decomposition of the negative electrode active material LiTO were detected from the X-ray diffraction measurement result of the surface not in contact with the solid electrolyte LLTO. Was done. This was a result supported by the phase diagram of Non-Patent Document 1. Further, Comparative Examples 4 to 6 compare the sintering densities of the bulk body (LLTO) for each firing temperature, but the bulk body sintering density of the solid electrolyte LLTO alone is Comparative Example 6 (1350° C. firing). It was confirmed that it was lacking in other than. Therefore, it is presumed that the bulk single-phase electrolyte exhibiting the desired ionic conductivity can be synthesized only in Comparative Example 6 fired at high temperature. However, similar to Comparative Example 3, the temperature condition of Comparative Example 6 is too high for the target temperature condition for forming the bonded body of the solid electrolyte LLTO and the negative electrode active material LiTO. On the other hand, in the present invention, it was examined to promote the crystal growth and to densify the material without converting the raw material into nanoparticles or raising the firing temperature. In the invention of the present application, lithium derived from the first layer, which is an active material, is also used as a raw material to form the second layer, which is a solid electrolyte. For example, the second layer is a negative electrode at a firing temperature of less than 1100°C. It was possible to make lithium titanate and lithium lanthanum titanate, which is a solid electrolyte, coexist at a dense and good interface.
１０ 固体電解質層、１２ 正極、１２ａ 正極活物質層、１２ｂ 集電体、１４ 負極、１４ａ 負極活物質層、１４ｂ 集電体、２０ リチウムイオン二次電池。 10 Solid electrolyte layer, 12 Positive electrode, 12a Positive electrode active material layer, 12b Current collector, 14 Negative electrode, 14a Negative electrode active material layer, 14b Current collector, 20 Lithium ion secondary battery.
Claims (9)
ペロブスカイト構造のチタン酸リチウムランタンを含む緻密層を含み前記第１層上を被覆した第２層と、を備え、
前記第１層と前記第２層との界面には抵抗層が存在しない、
複合体。 A first layer containing lithium titanate having a spinel structure;
Comprising a second layer coated over the first layer comprises a dense layer containing the lanthanum lithium titanate having a perovskite structure, and
There is no resistance layer at the interface between the first layer and the second layer,
Complex.
前記第２層の緻密層は、固体電解質層であり、
前記複合体は、負極／電解質複合体である、請求項１〜３のいずれか１項に記載の複合体。 The first layer is a negative electrode active material layer,
The dense layer of the second layer is a solid electrolyte layer,
The composite according to claim 1, wherein the composite is a negative electrode/electrolyte composite.
前記原料形成体を焼成し前記第１層に起因するリチウムをも原料として利用して前記第１層上にペロブスカイト構造のチタン酸リチウムランタンを含む緻密層を少なくとも形成させる第２層形成工程と、
を含む複合体の製造方法。 A raw material which contains at least plate-like particles of lanthanum titanate as a titanium source and a lanthanum source and may contain a powder of lanthanum titanate and a powder of titanium oxide on the first layer which is a molded body or a sintered body containing lithium titanate. A raw material forming step of producing the formed raw material forming body,
A second layer forming step in which the material forming body is fired and at least a dense layer containing lithium lanthanum titanate having a perovskite structure is formed on the first layer by using lithium derived from the first layer as a material;
A method for producing a composite containing.
前記第２層の緻密層は、固体電解質層であり、
前記複合体は、負極／電解質複合体である、請求項５〜８のいずれか１項に記載の複合体の製造方法。 The first layer is a negative electrode active material layer,
The dense layer of the second layer is a solid electrolyte layer,
The said composite is a negative electrode/electrolyte composite, The manufacturing method of the composite of any one of Claims 5-8.
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