JP2015227281A - Lithium titanate nano-particle, production method of the nano-particle, composite of lithium titanate nano-particle and carbon, electrode material consisting of the composite, electrode using the electrode material, and electrochemical element and electrochemical capacitor - Google Patents

Lithium titanate nano-particle, production method of the nano-particle, composite of lithium titanate nano-particle and carbon, electrode material consisting of the composite, electrode using the electrode material, and electrochemical element and electrochemical capacitor Download PDF

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JP2015227281A
JP2015227281A JP2015124876A JP2015124876A JP2015227281A JP 2015227281 A JP2015227281 A JP 2015227281A JP 2015124876 A JP2015124876 A JP 2015124876A JP 2015124876 A JP2015124876 A JP 2015124876A JP 2015227281 A JP2015227281 A JP 2015227281A
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lithium titanate
carbon
composite
titanate nanoparticles
lithium
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JP6012057B2 (en
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勝彦 直井
Katsuhiko Naoi
勝彦 直井
修一 石本
Shuichi Ishimoto
修一 石本
賢次 玉光
Kenji Tamamitsu
賢次 玉光
和子 直井
Kazuko Naoi
和子 直井
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Nippon Chemi Con Corp
Tokyo University of Agriculture and Technology NUC
Tokyo University of Agriculture
K and W Ltd
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Nippon Chemi Con Corp
Tokyo University of Agriculture and Technology NUC
Tokyo University of Agriculture
K and W Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01GCAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22Electrodes
    • H01G11/30Electrodes characterised by their material
    • H01G11/50Electrodes characterised by their material specially adapted for lithium-ion capacitors, e.g. for lithium-doping or for intercalation
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01GCAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/66Current collectors
    • H01G11/68Current collectors characterised by their material
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/13Energy storage using capacitors

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  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Electric Double-Layer Capacitors Or The Like (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a lithium titanate nano-particle formed by causing oxygen deficiency in lithium titanate with the reduction action of carbon and doping the oxygen deficiency parts with nitrogen, its production method and a composite of a lithium titanate nano-particle and carbon.SOLUTION: A composite powder in which a lithium titanate nano-particle is dispersed highly and carried in CNF is obtained by dissolving acetic acid and lithium acetate in a mixture of isopropanol and water to prepare a mixed solvent, charging the mixed solvent, a titanium alkoxide and carbon nano-fiber (CNF) into a rotating reactor, rotating an inner cylinder under a centrifugal force of 66,000 N(kgms) for 5 min to form a thin film of a product on the inner wall of the outer cylinder, applying shear stress and centrifugal force to the product to accelerate the chemical reaction so as to obtain CNF which is dispersed highly and carried with a precursor of a lithium titanate nano-particle, and then heating the obtained composite powder at 900°C in a nitrogen atmosphere for 3 min to make crystallization of lithium titanate progress.

Description

本発明は、チタン酸リチウムナノ粒子、チタン酸リチウムナノ粒子とカーボンの複合体とその製造方法、この複合体からなる電極材料、この電極材料を用いた電極及び電気化学素子及び電気化学キャパシタに関する。   The present invention relates to lithium titanate nanoparticles, a composite of lithium titanate nanoparticles and carbon, a method for producing the composite, an electrode material comprising the composite, an electrode using the electrode material, an electrochemical element, and an electrochemical capacitor.

現在、リチウム電池の電極としてリチウムを貯蔵、放出するカーボン材料等が用いられているが、マイナス電位が水素の還元分解電位より小さいので電解液の分解という危険性がある。そこで、特許文献1や特許文献2に記載のように、マイナス電位が水素の還元分解電位より大きいチタン酸リチウムの使用が検討されているが、チタン酸リチウムは出力特性が低いという問題点がある。そこで、チタン酸リチウムをナノ粒子化し、炭素に担持させた電極によって、出力特性を向上する試みがある。   At present, carbon materials that store and release lithium are used as electrodes of lithium batteries, but there is a risk of decomposition of the electrolyte because the negative potential is smaller than the reductive decomposition potential of hydrogen. Thus, as described in Patent Document 1 and Patent Document 2, the use of lithium titanate having a negative potential larger than the reductive decomposition potential of hydrogen has been studied. However, lithium titanate has a problem that output characteristics are low. . Therefore, there is an attempt to improve output characteristics with an electrode in which lithium titanate is made into nanoparticles and supported on carbon.

特開2007−160151号公報JP 2007-160151 A 特開2008−270795号公報JP 2008-270795 A

これらの特許文献に記載の発明は、旋回する反応器内で反応物にずり応力と遠心力を加えて、化学反応を促進させる方法(一般に、メカノケミカル反応と呼ばれる)によって、カーボンに分散担持されたチタン酸リチウムを得るものである。この場合、反応物としては、例えば、チタン酸リチウムの出発原料であるチタンアルコキシドと酢酸リチウム、及びカーボンナノチューブやケッチェンブラック等のカーボン、酢酸等を使用する。   The inventions described in these patent documents are dispersed and supported on carbon by a method (generally called mechanochemical reaction) that promotes a chemical reaction by applying shear stress and centrifugal force to a reactant in a rotating reactor. Lithium titanate is obtained. In this case, for example, titanium alkoxide and lithium acetate which are starting materials of lithium titanate, carbon such as carbon nanotube and ketjen black, acetic acid, and the like are used as the reactant.

これらの特許文献に記載のチタン酸リチウムナノ粒子を担持したカーボンを使用した電極は、優れた出力特性を発揮するものの、最近では、この種の電極において、さらに出力特性を向上させ、電気伝導度を向上させる要求がある。   Electrodes using carbon carrying lithium titanate nanoparticles described in these patent documents exhibit excellent output characteristics, but recently, in this type of electrode, the output characteristics have been further improved and the electric conductivity has been improved. There is a demand to improve.

本発明は、上述したような従来技術の問題点を解決するために提案されたものであって、その目的は、酸素欠損(酸素欠陥とも言う)部分に窒素をドープすることで、電極を構成した場合に出力特性及び電気伝導度を向上することを可能としたチタン酸リチウムナノ粒子、チタン酸リチウムナノ粒子とカーボンの複合体、その製造方法を提供することにある。また、本発明の他の目的は、前記複合体を用いた電極材料、この電極材料を用いた電極、電気化学素子及び電気化学キャパシタを提供することにある。   The present invention has been proposed in order to solve the above-described problems of the prior art, and its purpose is to constitute an electrode by doping nitrogen into an oxygen deficient (also referred to as oxygen defect) portion. It is an object of the present invention to provide lithium titanate nanoparticles, a composite of lithium titanate nanoparticles and carbon, and a method for producing the same, which can improve output characteristics and electrical conductivity. Another object of the present invention is to provide an electrode material using the composite, an electrode using the electrode material, an electrochemical element, and an electrochemical capacitor.

前記の目的を達成するため、本発明のチタン酸リチウムナノ粒子は、旋回する反応器内において、チタンアルコキシドと酢酸リチウム及びカーボン粒子を含む溶液に、ずり応力と遠心力を加えて反応させてチタン酸リチウムナノ粒子の前駆体を分散担持したカーボンを製造し、このチタン酸リチウムナノ粒子の前駆体を分散担持したカーボンを窒素雰囲気中で加熱して、カーボンの還元作用でチタン酸リチウムに酸素欠損を発生させ、その酸素欠損部に窒素をドープしたことを特徴とする。
この酸素欠損を有し、窒素をドープしたチタン酸リチウムナノ粒子とこれを高分散担持させたカーボンとから成る複合材料、この複合材料を使用した電極、この電極を用いた電気化学素子及び電気化学キャパシタ、前記複合体を構成するカーボンがグラファイトフラグメントのビルディングブロックであることも、本発明の一態様である。
In order to achieve the above object, the lithium titanate nanoparticles of the present invention are reacted with a solution containing titanium alkoxide, lithium acetate and carbon particles by applying shear stress and centrifugal force in a swirling reactor. Produces carbon with a dispersion-supported lithium oxide nanoparticle precursor, heats the carbon with the dispersion-supported lithium titanate nanoparticle precursor in a nitrogen atmosphere, and oxygen deficiency in the lithium titanate due to the reduction action of the carbon The oxygen deficient portion is doped with nitrogen.
Composite material composed of lithium titanate nanoparticles having oxygen vacancies and doped with nitrogen and carbon on which this is highly dispersed, electrode using the composite material, electrochemical device and electrochemical using the electrode It is also an embodiment of the present invention that the carbon constituting the capacitor and the composite is a building block of graphite fragments.

本発明のチタン酸リチウムナノ粒子の製造方法は、チタンアルコキシドと酢酸リチウムを溶媒とともに旋回する反応器内で反応させることで、反応物にずり応力と遠心力を加えて、化学反応を促進させてチタン酸リチウムナノ粒子の前駆体を製造し、このチタン酸リチウムナノ粒子の前駆体を窒素雰囲気中で加熱することを特徴とする。   In the method for producing lithium titanate nanoparticles of the present invention, titanium alkoxide and lithium acetate are reacted in a reactor swirling with a solvent, thereby applying a shear stress and centrifugal force to the reactant to promote a chemical reaction. A precursor of lithium titanate nanoparticles is manufactured, and the precursor of lithium titanate nanoparticles is heated in a nitrogen atmosphere.

本発明のチタン酸リチウムナノ粒子とカーボンの複合体の製造方法は、旋回する反応器内において、チタンアルコキシドと酢酸リチウム及びカーボン粒子を含む溶液に、ずり応力と遠心力を加えて反応させてチタン酸リチウムナノ粒子の前駆体を分散担持したカーボン製造し、このチタン酸リチウムナノ粒子の前駆体を分散担持したカーボンを窒素雰囲気中で加熱することを特徴とする。   In the method for producing a composite of lithium titanate nanoparticles and carbon according to the present invention, a titanium alkoxide, lithium acetate, and a solution containing carbon particles are reacted in a rotating reactor by applying shear stress and centrifugal force to react with titanium. It is characterized in that carbon in which a precursor of lithium acid nanoparticles is dispersedly supported is produced, and the carbon in which the precursor of lithium titanate nanoparticles is dispersedly supported is heated in a nitrogen atmosphere.

前記チタン酸リチウムナノ粒子の製造方法、またはチタン酸リチウムナノ粒子とカーボンの複合体の製造方法において、反応物と共に反応抑制剤を含む溶液にずり応力と遠心力を加えて反応させることも本発明の一態様である。   In the method for producing lithium titanate nanoparticles or the method for producing a composite of lithium titanate nanoparticles and carbon, the present invention may also be carried out by applying shear stress and centrifugal force to a solution containing a reaction inhibitor together with a reactant. It is one aspect | mode.

本発明によれば、旋回する反応器内において、チタンアルコキシドと酢酸リチウム及びカーボン粒子を含む溶液に、ずり応力と遠心力を加えて反応させてチタン酸リチウムナノ粒子の前駆体を分散担持したカーボンを製造し、このチタン酸リチウムナノ粒子の前駆体を分散担持したカーボンを窒素雰囲気中で加熱して、カーボンの還元作用でチタン酸リチウムに酸素欠損を発生させ、その酸素欠損部に窒素をドープすることにより、チタン酸リチウムナノ粒子を構成する結晶格子間に対するリチウムイオンの出入りが容易になる。その結果、このチタン酸リチウムナノ粒子をカーボンに担持させた複合体を電極や電気化学素子として使用した場合、その出力特性や容量を向上させることができる。   According to the present invention, carbon in which a precursor of lithium titanate nanoparticles is dispersed and supported by applying shear stress and centrifugal force to a solution containing titanium alkoxide, lithium acetate and carbon particles in a rotating reactor. The carbon containing the lithium titanate nanoparticle precursor dispersed and supported is heated in a nitrogen atmosphere to generate oxygen vacancies in the lithium titanate by the carbon reducing action, and the oxygen vacancies are doped with nitrogen. This facilitates the entry and exit of lithium ions between the crystal lattices constituting the lithium titanate nanoparticles. As a result, when the composite in which the lithium titanate nanoparticles are supported on carbon is used as an electrode or an electrochemical element, its output characteristics and capacity can be improved.

実施例1〜3のチタン酸リチウムナノ粒子とカーボンの複合体のTEM像を示す図面代用写真。The drawing substitute photograph which shows the TEM image of the composite_body | complex of lithium titanate nanoparticle of Examples 1-3 and carbon. 実施例1〜3のチタン酸リチウムナノ粒子とカーボンの複合体の放電挙動特性を示すグラフ。The graph which shows the discharge behavior characteristic of the composite of the lithium titanate nanoparticle and carbon of Examples 1-3. 実施例1〜3のチタン酸リチウムナノ粒子とカーボンの複合体の出力特性を示すグラフ。The graph which shows the output characteristic of the composite_body | complex of lithium titanate nanoparticle of Examples 1-3 and carbon. 本発明のチタン酸リチウムナノ粒子とカーボンの複合体において、酸素欠陥スピネル構造が存在することを示すグラフ。The graph which shows that an oxygen defect spinel structure exists in the composite_body | complex of lithium titanate nanoparticle and carbon of this invention. 本発明のチタン酸リチウムナノ粒子とカーボンの複合体において、チタン−窒素結合が存在することを示すグラフ。The graph which shows that a titanium-nitrogen bond exists in the composite_body | complex of lithium titanate nanoparticle and carbon of this invention. 各ガス雰囲気下におけるチタン酸リチウムナノ粒子を担持したカーボンのチタン価数変化を示すグラフ。The graph which shows the titanium valence change of the carbon which carry | supported the lithium titanate nanoparticle in each gas atmosphere. 本発明のチタン酸リチウムナノ粒子とカーボンの複合体の構造を示すモデル図。The model figure which shows the structure of the composite_body | complex of lithium titanate nanoparticle and carbon of this invention. 本発明の製造方法に使用する反応器の一例を示す斜視図。The perspective view which shows an example of the reactor used for the manufacturing method of this invention. 本発明の実施例4と比較例6の充放電試験の結果を示すグラフ。The graph which shows the result of the charging / discharging test of Example 4 and Comparative Example 6 of this invention.

本発明を実施するための形態について、以下、説明する。   Hereinafter, modes for carrying out the present invention will be described.

(メカノケミカル反応)
本発明で用いる反応方法は、本出願人等が先に特許出願した特許文献1及び特許文献2に示した方法と同様のメカノケミカル反応であって、化学反応の過程で、旋回する反応器内で反応物にずり応力と遠心力を加えて化学反応を促進させるものである。
(Mechanochemical reaction)
The reaction method used in the present invention is a mechanochemical reaction similar to the method shown in Patent Document 1 and Patent Document 2 previously filed by the present applicant and the like, and in a reactor that rotates in the course of the chemical reaction. In this method, shear reaction and centrifugal force are applied to the reactant to promote chemical reaction.

この反応方法は、例えば、図8に示すような反応器を用いて行うことができる。図8に示すように、反応器は、開口部にせき板1−2を有する外筒1と、貫通孔2−1を有し旋回する内筒2からなる。この反応器の内筒内部に反応物を投入し、内筒を旋回することによってその遠心力で内筒内部の反応物が内筒の貫通孔を通って外筒の内壁1−3に移動する。この時反応物は内筒の遠心力によって外筒の内壁に衝突し、薄膜状となって内壁の上部へずり上がる。この状態では反応物には内壁との間のずり応力と内筒からの遠心力の双方が同時に加わり、薄膜状の反応物に大きな機械的エネルギーが加わることになる。この機械的なエネルギーが反応に必要な化学エネルギー、いわゆる活性化エネルギーに転化するものと思われるが、短時間で反応が進行する。   This reaction method can be performed using, for example, a reactor as shown in FIG. As shown in FIG. 8, the reactor includes an outer cylinder 1 having a cough plate 1-2 at an opening and an inner cylinder 2 having a through hole 2-1 and swirling. By putting the reactant into the inner cylinder of the reactor and turning the inner cylinder, the reactant inside the inner cylinder moves to the inner wall 1-3 of the outer cylinder through the through hole of the inner cylinder by the centrifugal force. . At this time, the reaction product collides with the inner wall of the outer cylinder by the centrifugal force of the inner cylinder, and forms a thin film and slides up to the upper part of the inner wall. In this state, both the shear stress between the inner wall and the centrifugal force from the inner cylinder are simultaneously applied to the reactant, and a large mechanical energy is applied to the thin-film reactant. This mechanical energy seems to be converted into chemical energy required for the reaction, so-called activation energy, but the reaction proceeds in a short time.

この反応において、薄膜状であると反応物に加えられる機械的エネルギーは大きなものとなるため、薄膜の厚みは5mm以下、好ましくは2.5mm以下、さらに好ましくは1.0mm以下である。なお、薄膜の厚みはせき板の幅、反応液の量によって設定することができる。   In this reaction, since the mechanical energy applied to the reaction product is large when it is in the form of a thin film, the thickness of the thin film is 5 mm or less, preferably 2.5 mm or less, more preferably 1.0 mm or less. The thickness of the thin film can be set according to the width of the dam plate and the amount of the reaction solution.

この反応方法は、反応物に加えられるずり応力と遠心力の機械的エネルギーによって実現できるものと考えられるが、このずり応力と遠心力は内筒内の反応物に加えられる遠心力によって生じる。したがって、本発明に必要な内筒内の反応物に加えられる遠心力は1500N(kgms-2)以上、好ましくは60000N(kgms-2)以上、さらに好ましくは270000N(kgms-2)以上である。 This reaction method is considered to be realized by the mechanical energy of the shear stress and the centrifugal force applied to the reactant, and the shear stress and the centrifugal force are generated by the centrifugal force applied to the reactant in the inner cylinder. Thus, the centrifugal force applied to the reactants in the inner cylinder necessary for the present invention is 1500 N (kgms -2) or more, preferably 60000N (kgms -2) or more, more preferably 270000N (kgms -2) or more.

この反応方法においては、反応物にずり応力と遠心力の双方の機械的エネルギーが同時に加えられることによって、このエネルギーが化学エネルギーに転化することによるものと思われるが、従来にない速度で化学反応を促進させることができる。   In this reaction method, mechanical energy of both shear stress and centrifugal force is applied to the reactant at the same time, which seems to be due to the conversion of this energy into chemical energy. Can be promoted.

(チタン酸リチウム)
本発明に係るチタン酸リチウムナノ粒子を生成するために、例えば、チタンアルコキシドなどのチタン源、酢酸リチウム、硝酸リチウム、炭酸リチウム、水酸化リチウムなどのリチウム源を出発原料として使用し、前記メカノケミカル反応により、チタン酸リチウムナノ粒子の前駆体を生成する。このチタン酸リチウムナノ粒子の前駆体を窒素雰囲気中で加熱することにより、酸素欠陥のサイトに窒素がドープされた本発明のチタン酸リチウムナノ粒子が生成される。
(Lithium titanate)
In order to produce lithium titanate nanoparticles according to the present invention, for example, a titanium source such as titanium alkoxide, or a lithium source such as lithium acetate, lithium nitrate, lithium carbonate, or lithium hydroxide is used as a starting material, and the mechanochemical By the reaction, a precursor of lithium titanate nanoparticles is generated. By heating the precursor of the lithium titanate nanoparticles in a nitrogen atmosphere, the lithium titanate nanoparticles of the present invention in which nitrogen is doped at sites of oxygen defects are generated.

(カーボン)
反応過程で所定のカーボンを加えることによって、5〜20nmのチタン酸リチウムを高分散担持させたカーボンを得ることができる。すなわち、反応器の内筒の内部に金属塩と上記の反応抑制剤と所定のカーボンを投入して、内筒を旋回して金属塩と上記の反応抑制剤とカーボンを混合、分散する。さらに内筒を旋回させながら水酸化ナトリウムなどの触媒を投入して加水分解、縮合反応を進行させ、金属酸化物を生成すると共に、この金属酸化物とカーボンを分散状態で、混合する。反応終了と共に、金属酸化物ナノ粒子を高分散担持させたカーボンを形成することができる。
(carbon)
By adding predetermined carbon during the reaction process, carbon in which 5 to 20 nm of lithium titanate is highly dispersed and supported can be obtained. That is, a metal salt, the above reaction inhibitor, and a predetermined carbon are introduced into the inner cylinder of the reactor, and the inner cylinder is rotated to mix and disperse the metal salt, the above reaction inhibitor, and carbon. Further, while turning the inner cylinder, a catalyst such as sodium hydroxide is added to cause hydrolysis and condensation reaction to proceed to produce a metal oxide, and the metal oxide and carbon are mixed in a dispersed state. Along with the completion of the reaction, carbon in which metal oxide nanoparticles are supported in a highly dispersed state can be formed.

ここで用いるカーボンとしては、ケッチェンブラック、アセチレンブラック等のカーボンブラック、カーボンナノチューブ、カーボンナノホーン、無定形炭素、炭素繊維、天然黒鉛、人造黒鉛、活性炭、メソポーラス炭素等を挙げることができ、これらの複合材を用いることもできる。   Examples of the carbon used here include carbon blacks such as ketjen black and acetylene black, carbon nanotubes, carbon nanohorns, amorphous carbon, carbon fibers, natural graphite, artificial graphite, activated carbon, mesoporous carbon, and the like. Composite materials can also be used.

(溶媒)
溶媒としては、アルコール類、水、これらの混合溶媒を用いることができる。例えば、酢酸と酢酸リチウムをイソプロパノールと水の混合物に溶解した混合溶媒を使用することができる。
(solvent)
As the solvent, alcohols, water, or a mixed solvent thereof can be used. For example, a mixed solvent in which acetic acid and lithium acetate are dissolved in a mixture of isopropanol and water can be used.

(反応抑制剤)
特許文献2に記載のように、前記メカノケミカル反応を適用する所定の金属アルコキシドに、反応抑制剤として該金属アルコキシドと錯体を形成する所定の化合物を添加することができる。これにより、化学反応が促進しすぎるのを抑制することができる。
(Reaction inhibitor)
As described in Patent Document 2, a predetermined compound that forms a complex with the metal alkoxide can be added as a reaction inhibitor to the predetermined metal alkoxide to which the mechanochemical reaction is applied. Thereby, it can suppress that a chemical reaction accelerates | stimulates too much.

すなわち、金属アルコキシドに、これと錯体を形成する酢酸等の所定の化合物を該金属アルコキシド1モルに対して、1〜3モル添加して錯体を形成することにより、反応を抑制、制御することができることが分かった。なお、この反応によって生成されるのは、金属と酸化物の複合体のナノ粒子、例えば、チタン酸リチウムナノ粒子の前駆体である、リチウムと酸化チタンの複合体のナノ粒子であり、これを焼成することにより、チタン酸リチウムの結晶が得られる。   That is, the reaction can be suppressed and controlled by adding 1 to 3 mol of a predetermined compound such as acetic acid that forms a complex with metal alkoxide to 1 mol of the metal alkoxide to form a complex. I understood that I could do it. It is to be noted that a metal-oxide composite nanoparticle, for example, a lithium-titanium oxide composite nanoparticle, which is a precursor of lithium titanate nanoparticle, is generated by this reaction. By firing, crystals of lithium titanate are obtained.

このように、反応抑制剤として酢酸等の所定の化合物を添加することにより、化学反応が促進しすぎるのを抑制することができるのは、酢酸等の所定の化合物が金属アルコキシドと安定な錯体を形成するためであると考えられる。   Thus, by adding a predetermined compound such as acetic acid as a reaction inhibitor, it is possible to suppress the chemical reaction from being promoted too much because the predetermined compound such as acetic acid can form a stable complex with the metal alkoxide. It is thought that it is for forming.

金属アルコキシドと錯体を形成することができる物質としては、酢酸の他、クエン酸、蓚酸、ギ酸、乳酸、酒石酸、フマル酸、コハク酸、プロピオン酸、レプリン酸等のカルボン酸、EDTA等のアミノポリカルボン酸、トリエタノールアミン等のアミノアルコールに代表される錯化剤が挙げられる。   Substances capable of forming a complex with a metal alkoxide include acetic acid, carboxylic acids such as citric acid, succinic acid, formic acid, lactic acid, tartaric acid, fumaric acid, succinic acid, propionic acid, and repuric acid, and aminopolyesters such as EDTA. Examples include complexing agents represented by amino alcohols such as carboxylic acid and triethanolamine.

(加熱)
本発明は、チタン酸リチウムを窒素雰囲気中で加熱することによって、酸素欠陥が生じて、このサイトにリチウムが吸蔵、脱離するので、容量、出力特性が向上し、さらにこの酸素欠陥のサイトに窒素がドープして、チタン酸リチウムの電気伝導性が向上し、出力特性が向上するというメカニズムによるものと考えられる。
(heating)
In the present invention, when lithium titanate is heated in a nitrogen atmosphere, oxygen defects are generated, and lithium is occluded and desorbed at this site. It is considered that this is due to a mechanism in which nitrogen is doped to improve the electrical conductivity of lithium titanate and improve the output characteristics.

得られたチタン酸リチウムナノ粒子の前駆体の焼成工程において、室温から700〜900℃まで急熱することによって、チタン酸リチウムの結晶化が良好に進行することが分かった。この温度未満では良好な結晶化の進行が得られず、この温度を越えると相転移によって、エネルギー貯蔵特性の良好なチタン酸リチウムが得られない。   It was found that crystallization of lithium titanate proceeds well by rapid heating from room temperature to 700 to 900 ° C. in the step of firing the precursor of the obtained lithium titanate nanoparticles. Below this temperature, good progress of crystallization cannot be obtained, and when this temperature is exceeded, lithium titanate with good energy storage characteristics cannot be obtained due to phase transition.

(電極)
本発明により得られたチタン酸リチウムナノ粒子とカーボンの複合体は、バインダーと混錬、成型し、電気化学素子の電極、すなわち電気エネルギー貯蔵用電極とすることができ、その電極は高出力特性、高容量特性を示す。
(electrode)
The composite of lithium titanate nanoparticles and carbon obtained by the present invention can be kneaded and molded with a binder to be an electrode of an electrochemical element, that is, an electrode for storing electrical energy, and the electrode has high output characteristics. Show high capacity characteristics.

(電気化学素子)
この電極を用いることができる電気化学素子は、リチウムイオンを含有する電解液を用いる電気化学キャパシタ、電池である。すなわち、本発明の電極は、リチウムイオンの吸蔵、脱着を行うことができ、負極として作動する。したがって、リチウムイオンを含有する電解液を用い、対極として活性炭、リチウムが吸蔵、脱着する金属酸化物等を用いることによって、電気化学キャパシタ、電池を構成することができる。
(Electrochemical element)
Electrochemical elements that can use this electrode are electrochemical capacitors and batteries that use an electrolyte containing lithium ions. That is, the electrode of the present invention can occlude and desorb lithium ions and operates as a negative electrode. Therefore, an electrochemical capacitor and a battery can be configured by using an electrolytic solution containing lithium ions and using, as a counter electrode, activated carbon, a metal oxide that occludes and desorbs lithium, and the like.

(実施例1)
チタンアルコキシド1モルに対して、酢酸1.8モル、酢酸リチウム1モルとなる量の酢酸と酢酸リチウムをイソプロパノールと水の混合物に溶解して混合溶媒を作製した。この混合溶媒とチタンアルコキシド、カーボンナノファイバー(CNF)を旋回反応器内に投入し、66,000N(kgms-2)の遠心力で5分間、内筒を旋回して外筒の内壁に反応物の薄膜を形成すると共に、反応物にずり応力と遠心力を加えて化学反応を促進させ、チタン酸リチウムナノ粒子の前駆体を高分散担持したCNFを得た。この場合、混合溶媒に溶解するチタンアルコキシドとCNFの量は、得られる複合体の組成が、チタン酸リチウム/CNFが、70/30の質量比(w/w)となるように設定した。
Example 1
A mixed solvent was prepared by dissolving acetic acid and lithium acetate in an amount of 1.8 mol of acetic acid and 1 mol of lithium acetate in a mixture of isopropanol and water with respect to 1 mol of titanium alkoxide. This mixed solvent, titanium alkoxide, and carbon nanofiber (CNF) are put into a swirl reactor, and the inner cylinder is swirled for 5 minutes with a centrifugal force of 66,000 N (kgms -2 ), and the reaction product is placed on the inner wall of the outer cylinder. In addition, a chemical reaction was promoted by applying shear stress and centrifugal force to the reaction product to obtain CNF carrying a highly dispersed lithium titanate nanoparticle precursor. In this case, the amount of titanium alkoxide and CNF dissolved in the mixed solvent was set such that the composition of the obtained composite had a mass ratio (w / w) of lithium titanate / CNF of 70/30.

得られたチタン酸リチウムナノ粒子の前駆体を高分散担持させたCNFを、真空中において80℃で17時間乾燥することにより、チタン酸リチウムナノ粒子の前駆体がCNFに高分散担持された複合体粉末を得た。   The obtained lithium titanate nanoparticle precursor with high dispersion support was dried at 80 ° C. for 17 hours in a vacuum to obtain a composite in which the lithium titanate nanoparticle precursor was supported with high dispersion on CNF. A body powder was obtained.

得られたチタン酸リチウムナノ粒子の前駆体がCNFに高分散担持された複合体粉末を、窒素雰囲気中で900℃で加熱することによってリチウムを含有するチタン酸化物の結晶化を進行させ、チタン酸リチウムのナノ粒子がカーボンナノファイバーに高分散担持された複合体粉末を得た。   The resulting composite powder in which the precursor of lithium titanate nanoparticles is highly dispersed and supported on CNF is heated at 900 ° C. in a nitrogen atmosphere to promote crystallization of lithium-containing titanium oxide. A composite powder was obtained in which lithium acid nanoparticles were highly dispersed and supported on carbon nanofibers.

(実施例2)
前記実施例1において窒素雰囲気中で900℃で加熱する代わりに、800℃で加熱した。
(実施例3)
前記実施例1において窒素雰囲気中で900℃で加熱する代わりに、700℃で加熱した。
(Example 2)
Instead of heating at 900 ° C. in a nitrogen atmosphere in Example 1, heating was performed at 800 ° C.
(Example 3)
Instead of heating at 900 ° C. in a nitrogen atmosphere in Example 1, heating was performed at 700 ° C.

(比較例1)
前記実施例1において窒素雰囲気中で900℃で加熱する代わりに、真空中で900℃で加熱した。
(比較例2)
前記実施例1において窒素雰囲気中で900℃で加熱する代わりに、、真空中で800℃で加熱した。
(比較例3)
前記実施例1において窒素雰囲気中で900℃で加熱する代わりに、真空中で700℃で加熱した。
(比較例4)
前記実施例1において窒素雰囲気中で900℃で加熱する代わりに、空気(酸化雰囲気)中で900℃で加熱した。
(比較例5)
前記実施例1において窒素雰囲気中で900℃で加熱する代わりに、アルゴン/水素中(還元雰囲気)で900℃で加熱した。
(Comparative Example 1)
Instead of heating at 900 ° C. in a nitrogen atmosphere in Example 1, heating was performed at 900 ° C. in a vacuum.
(Comparative Example 2)
Instead of heating at 900 ° C. in a nitrogen atmosphere in Example 1, heating was performed at 800 ° C. in a vacuum.
(Comparative Example 3)
Instead of heating at 900 ° C. in a nitrogen atmosphere in Example 1, heating was performed at 700 ° C. in vacuum.
(Comparative Example 4)
Instead of heating at 900 ° C. in a nitrogen atmosphere in Example 1, heating was performed at 900 ° C. in air (oxidizing atmosphere).
(Comparative Example 5)
Instead of heating at 900 ° C. in a nitrogen atmosphere in Example 1, heating was performed at 900 ° C. in argon / hydrogen (reducing atmosphere).

このようにして得られた実施例1〜3のチタン酸リチウムナノ粒子を担持したカーボンの各TEM像を図1に示した。図1においては5nm〜20nmのチタン酸リチウムのナノ粒子がカーボンナノファイバーに高分散担持していることが分かる。   Each TEM image of the carbon carrying the lithium titanate nanoparticles of Examples 1 to 3 thus obtained is shown in FIG. In FIG. 1, it can be seen that 5 to 20 nm lithium titanate nanoparticles are highly dispersed and supported on the carbon nanofibers.

特に、図1の各TEM像にみられるように、本発明の「チタン酸リチウムナノ粒子とカーボンの複合体」は、CNFがつながった「グラファイトフラグメントのビルディングブロック」をとっており、この構造体にチタン酸リチウムナノ粒子が高分散担持されている。   In particular, as seen in each TEM image of FIG. 1, the “composite of lithium titanate nanoparticles and carbon” of the present invention takes a “building block of graphite fragments” in which CNF is connected. In addition, lithium titanate nanoparticles are supported in a highly dispersed state.

図7にこの構造のモデル図を示す。図7の左図の従来の電極では、チタン酸リチウムの粒子の表面にカーボンが担持し、このカーボンによってチタン酸リチウム粒子が接合された構造となっている。したがって、粒子内のリチウムイオンの遅い応答性のため低出力である。これに対して、図7の右図の本発明の構造では、チタン酸リチウムがナノ粒子となっているため、表面での速い応答性が支配的であるため、高出力であり、さらにカーボンがグラファイトフラグメントのビルディングブロックをとっているため、電気伝導度が向上して、さらに出力特性が向上する。   FIG. 7 shows a model diagram of this structure. 7 has a structure in which carbon is supported on the surface of lithium titanate particles, and the lithium titanate particles are joined by the carbon. Therefore, the output is low due to the slow response of lithium ions in the particles. On the other hand, in the structure of the present invention shown in the right diagram of FIG. 7, since lithium titanate is a nanoparticle, the fast response on the surface is dominant, so the output is high and the carbon Since the building blocks are made of graphite fragments, the electrical conductivity is improved and the output characteristics are further improved.

前記のように構成した実施例1〜3及び比較例1〜3で得られた複合体粉末をバインダーとしてのポリフッ化ビニリデンPVDFと共に(Li4Ti512/CNF/PVDF 56:24:20)、SUS板上に溶接されたSUSメッシュ中に投入し、作用電極W.E.とした。前記電極上にセパレータと対極C.E.及び参照極としてLiフォイルを乗せ、電解液として、1.0M 四フッ化ホウ酸リチウム(LiBF4)/炭酸エチレンEC:炭酸ジメチルDEC(1:1 w/w)を浸透させて、セルとした。 The composite powders obtained in Examples 1 to 3 and Comparative Examples 1 to 3 configured as described above were combined with polyvinylidene fluoride PVDF as a binder (Li 4 Ti 5 O 12 / CNF / PVDF 56:24:20). , Put into a SUS mesh welded on the SUS plate, E. It was. A separator and a counter electrode on the electrode C.I. E. Lithium foil was placed as a reference electrode, and 1.0 M lithium tetrafluoroborate (LiBF 4 ) / ethylene carbonate EC: dimethyl carbonate DEC (1: 1 w / w) was infiltrated as an electrolyte to obtain a cell. .

前記のようにして得られた実施例1〜3と比較例1〜3の複合体粉末を用いた電極を有するセルについて、その充放電挙動とそれに基づいて算出した容量を図2に、出力特性を図3に示す。図2及び図3において、左側のグラフが実施例1〜3、右側のグラフが比較例1〜3を示している。この場合、作用電圧は1.0−3.0Vであり、スキャンレートは10Cである。また、加熱時間は、各3分間である。   Regarding the cells having electrodes using the composite powders of Examples 1 to 3 and Comparative Examples 1 to 3 obtained as described above, the charge / discharge behavior and the capacity calculated based on the behavior are shown in FIG. Is shown in FIG. 2 and 3, the left graph shows Examples 1 to 3, and the right graph shows Comparative Examples 1 to 3. In this case, the working voltage is 1.0-3.0V, and the scan rate is 10C. The heating time is 3 minutes each.

図2から分かるように、窒素雰囲気中で加熱した実施例1〜3の複合体粉末を使用したセルは、真空中で加熱した比較例1〜3の複合体粉末を使用したセルに比較して、容量が増加していることが分かる。特に、比較例1の真空中で900℃まで加熱した複合体粉末を使用したセルが、従来技術では最も容量が大きかったが、実施例1〜3のセルはいずれも、比較例1の容量を大きく上回っている。特に、図2の右側のグラフから分かるように、700℃及び800℃で加熱した実施例2,3が、900℃まで加熱した実施例1に比較して、大きな容量が得られている。   As can be seen from FIG. 2, the cells using the composite powders of Examples 1 to 3 heated in a nitrogen atmosphere were compared to the cells using the composite powders of Comparative Examples 1 to 3 heated in vacuum. It can be seen that the capacity is increasing. In particular, the cell using the composite powder heated to 900 ° C. in the vacuum of Comparative Example 1 had the largest capacity in the prior art, but all of the cells of Examples 1 to 3 had the capacity of Comparative Example 1. It is much higher. In particular, as can be seen from the graph on the right side of FIG. 2, the capacities of Examples 2 and 3 heated to 700 ° C. and 800 ° C. are larger than those of Example 1 heated to 900 ° C.

図3は、横軸にC-rateを、縦軸に放電容量維持率(%)を取った各セルの出力特性を示すグラフである。この図3から分かるように、C-rateが200Cの時点における放電容量維持率は、実施例1〜3のセルが比較例1〜3のセルを大きく上回っている。ここでも、注目すべき点は、真空中で加熱した比較例1〜3のセルでは、高温の900℃の場合が最も優れた出力特性を示すのに対して、実施例1〜3のセルの場合は、900℃よりも700℃及び800℃の方が優れた出力特性を示す点である。容量や充放電特性について差がなかった実施例2と3ではあるが、出力特性については700℃の方が優れている。   FIG. 3 is a graph showing the output characteristics of each cell with the C-rate on the horizontal axis and the discharge capacity retention rate (%) on the vertical axis. As can be seen from FIG. 3, the discharge capacity retention rate when the C-rate is 200 C is significantly higher in the cells of Examples 1 to 3 than in Comparative Examples 1 to 3. Here, too, it should be noted that in the cells of Comparative Examples 1 to 3 heated in a vacuum, the high temperature of 900 ° C. showed the most excellent output characteristics, whereas the cells of Examples 1 to 3 In this case, 700 ° C. and 800 ° C. show better output characteristics than 900 ° C. Although it is Example 2 and 3 in which there was no difference regarding a capacity | capacitance or a charge / discharge characteristic, 700 degreeC is more excellent about an output characteristic.

本発明の複合体において、酸素欠陥を確認するために、図4に実施例1と比較例1,4のXPS_O 1sの分析結果を示す。
このXPS_O 1sの分析結果によれば、実施例1では酸素欠陥に由来するスペクトルを示すO 1s結合エネルギーのピーク533〜534eVが確認され、比較例1,4においては、通常の酸化物に由来するスペクトルを示す結合エネルギーのピーク530eVが確認される。
In order to confirm oxygen defects in the composite of the present invention, FIG. 4 shows the XPS_O 1s analysis results of Example 1 and Comparative Examples 1 and 4.
According to the analysis result of XPS_O 1s, in Example 1, O 1s binding energy peaks 533 to 534 eV showing a spectrum derived from oxygen defects are confirmed, and in Comparative Examples 1 and 4, the peak is derived from a normal oxide. A peak 530 eV of binding energy showing a spectrum is confirmed.

本発明の複合体において、窒素ドープによりTi−N結合が存在していることを確認するために、図5に実施例1と比較例1,4のXPS_N 1sの分析結果を示す。
このXPS_N 1sの分析結果によれば、実施例1では、Ti−N結合を示すN 1s結合エネルギーのピーク396eVが検知されており、窒素がドープしていることが確認される。一方、比較例1,4では、396eVではN1s結合エネルギーのピークは確認されず、Ti−N結合が存在しない、すなわち窒素ドープが行われていないことが確認される。このように窒素ドープが確認された実施例1の複合体においては、チタン酸リチウムの電気伝導性が向上し、その結果、この複合体を用いた電極や電気化学素子において出力特性が向上する。
FIG. 5 shows the XPS_N 1s analysis results of Example 1 and Comparative Examples 1 and 4 in order to confirm the presence of Ti—N bonds by nitrogen doping in the composite of the present invention.
According to the XPS_N 1s analysis result, in Example 1, the peak 396 eV of N 1s bond energy indicating Ti—N bond is detected, and it is confirmed that nitrogen is doped. On the other hand, in Comparative Examples 1 and 4, the peak of N1s bond energy is not confirmed at 396 eV, and it is confirmed that no Ti-N bond exists, that is, nitrogen doping is not performed. Thus, in the composite of Example 1 in which nitrogen doping was confirmed, the electrical conductivity of lithium titanate was improved, and as a result, the output characteristics were improved in electrodes and electrochemical devices using this composite.

本発明の複合体において、Tiの価数変化が生じていることを確認するために、図6に実施例1と比較例1,4のXPS_Ti 2Pの分析結果を示す。
このXPS_Ti 2P分析結果によれば、実施例1では、Ti3を示すTi 2P結合エネルギーのピーク458〜457eVが検知されており、3価のチタンが存在していることが確認される。一方、比較例1,4では、Ti4を示すTi 2P結合エネルギーのピーク460〜459eVが検知されており、4価のチタンが存在していることが確認される。なお、実施例1及び比較例1,4では、Ti2を示すTi 2P結合エネルギーのピーク455〜454eVは検知されず、2価のチタンが存在しないことが確認される。
In order to confirm that the valence change of Ti occurs in the composite of the present invention, FIG. 6 shows the XPS_Ti 2P analysis results of Example 1 and Comparative Examples 1 and 4.
According to the XPS_Ti 2P analysis result, in Example 1, peaks 458 to 457 eV of Ti 2P binding energy indicating Ti 3 are detected, and it is confirmed that trivalent titanium is present. On the other hand, in Comparative Examples 1 and 4, peaks 460 to 459 eV of Ti 2P binding energy indicating Ti 4 are detected, and it is confirmed that tetravalent titanium is present. In Example 1 and Comparative Examples 1 and 4, the peak 455~454eV of Ti 2P binding energy showing the Ti 2 is not detected, that divalent titanium does not exist is confirmed.

このように、図6の分析結果によれば、本発明の窒素雰囲気中加熱では真空中での加熱よりチタンの価数が4価から3価に減少していることが分かる。このことから、酸素欠陥によってチタンの価数が減少し、このサイトにリチウムが吸蔵、脱離するので、本発明の複合体を用いた電極や電気化学素子において容量、出力特性が向上する。   Thus, according to the analysis result of FIG. 6, it can be seen that the valence of titanium is reduced from tetravalent to trivalent in heating in a nitrogen atmosphere of the present invention compared to heating in vacuum. From this, the valence of titanium decreases due to oxygen defects, and lithium is occluded and desorbed at this site, so that the capacity and output characteristics of the electrode and electrochemical device using the composite of the present invention are improved.

前記図2及び図3に示した実施例1〜3と比較例1〜3との比較から明らかなように、窒素雰囲気中で加熱する本発明においては、実施例1,2の700〜800℃の方が実施例3の900℃よりも電気的特性が向上する。これに対して、真空中で加熱する比較例では、900℃の比較例1が最も特性が良い。このことは、真空中より窒素雰囲気中での加熱の方が低温の加熱でより優れた特性を引き出せることを示している。   As is clear from the comparison between Examples 1 to 3 and Comparative Examples 1 to 3 shown in FIGS. 2 and 3, in the present invention where heating is performed in a nitrogen atmosphere, 700 to 800 ° C. of Examples 1 and 2 is used. This improves the electrical characteristics more than 900 ° C. in Example 3. On the other hand, in the comparative example heated in a vacuum, the comparative example 1 of 900 degreeC has the best characteristic. This indicates that heating in a nitrogen atmosphere can bring out more excellent characteristics with low-temperature heating than in vacuum.

(実施例4)
チタンアルコキシド1モルに対して、酢酸1.8モル、酢酸リチウム1モルとなる量の酢酸と酢酸リチウムをイソプロパノールと水の混合物に溶解して混合溶媒を作製した。この混合溶媒とチタンアルコキシド、イソプロピルアルコール、カーボンナノファイバーを旋回反応器内に投入し、66,000N(kgms-2)の遠心力で5分間、内筒を旋回して外筒の内壁に反応物の薄膜を形成すると共に、反応物にずり応力と遠心力を加えて化学反応を促進させ、チタン酸リチウムの前駆体を高分散担持したケッチェンブラックを得た。
Example 4
A mixed solvent was prepared by dissolving acetic acid and lithium acetate in an amount of 1.8 mol of acetic acid and 1 mol of lithium acetate in a mixture of isopropanol and water with respect to 1 mol of titanium alkoxide. This mixed solvent, titanium alkoxide, isopropyl alcohol, and carbon nanofibers are put into a swirl reactor, and the inner cylinder is swirled for 5 minutes with a centrifugal force of 66,000 N (kgms -2 ), and the reactant is put on the inner wall of the outer cylinder. A ketjen black carrying a highly dispersed lithium titanate precursor was obtained by applying a shear stress and a centrifugal force to the reaction product to promote a chemical reaction.

得られたチタン酸リチウムの前駆体を高分散担持させたカーボンナノファイバーを、真空中において80℃で17時間乾燥することにより、チタン酸リチウムの前駆体がカーボンナノファイバーに高分散担持された複合体粉末を得た。   The obtained carbon nanofibers with a highly dispersed precursor of lithium titanate are dried in a vacuum at 80 ° C. for 17 hours to obtain a composite in which the precursor of lithium titanate is highly dispersed and supported on carbon nanofibers. A body powder was obtained.

得られたチタン酸リチウムの前駆体がカーボンナノファイバーに高分散担持された複合体粉末を、窒素雰囲気中で800℃まで急速加熱することによってリチウムを含有するチタン酸化物の結晶化を進行させ、チタン酸リチウムのナノ粒子がカーボンナノファイバーに高分散担持された複合体粉末を得た。   The resulting composite powder in which the precursor of lithium titanate is highly dispersed and supported on carbon nanofibers is rapidly heated to 800 ° C. in a nitrogen atmosphere to promote crystallization of lithium-containing titanium oxide, A composite powder in which lithium titanate nanoparticles were highly dispersed and supported on carbon nanofibers was obtained.

上記のようにして得られた複合体粉末9重量部と、1重量部のPVDF(ポリフッ化ビニリデン)バインダーを混練し、圧延してシートを形成した。このシートを真空乾燥後、銅箔に接合し、負極とした。   9 parts by weight of the composite powder obtained as described above and 1 part by weight of PVDF (polyvinylidene fluoride) binder were kneaded and rolled to form a sheet. This sheet was vacuum dried and then joined to a copper foil to obtain a negative electrode.

また、活性炭(クラレケミカル社製、YP−17)8重量部と、1重量部のPTFEバインダー(ポリテトラフルオロエチレン)、導電性材料としてカーボンナノファイバー1重量部とを混練し、圧延してシートを形成した。このシートを真空乾燥後、アルミニウム箔に接合し、正極とした。 Also, 8 parts by weight of activated carbon (manufactured by Kuraray Chemical Co., Ltd., YP-17), 1 part by weight of PTFE binder (polytetrafluoroethylene), and 1 part by weight of carbon nanofiber as a conductive material are kneaded, rolled and sheeted Formed. This sheet was vacuum dried and then joined to an aluminum foil to form a positive electrode.

これらの電極を、LiBF4、プロピレンカーボネート溶液を注入したビーカーに、セルロース系のセパレータを介して、対向させてハイブリッドキャパシタセルを作製した。 These electrodes were made to face each other through a cellulosic separator in a beaker into which LiBF 4 and a propylene carbonate solution had been injected to produce a hybrid capacitor cell.

(比較例6)
加熱を真空中で行った以外は実施例4と同様にしてハイブリッドキャパシタセルを作製した。
これらのセルについて、定電流で充放電試験を行い、エネルギー密度とパワー密度を測定したところ、図9に示すような結果が得られた。図9からわかるように、実施例4のハイブリッドキャパシタのレート特性は比較例6のハイブリッドキャパシタより良好であり、400Cでの容量保持率は1.25倍になっている。
(Comparative Example 6)
A hybrid capacitor cell was produced in the same manner as in Example 4 except that heating was performed in vacuum.
When these cells were subjected to a charge / discharge test at a constant current and the energy density and power density were measured, results as shown in FIG. 9 were obtained. As can be seen from FIG. 9, the rate characteristics of the hybrid capacitor of Example 4 are better than the hybrid capacitor of Comparative Example 6, and the capacity retention at 400 C is 1.25 times.

1…外筒
1−2…せき板
1−3…内壁
2…内筒
2−1…貫通孔
DESCRIPTION OF SYMBOLS 1 ... Outer cylinder 1-2 ... Baffle 1-3 ... Inner wall 2 ... Inner cylinder 2-1 ... Through-hole

Claims (10)

チタン酸リチウムナノ粒子の前駆体を窒素雰囲気中で加熱して結晶化したチタン酸リチウムナノ粒子であって、
前記窒素雰囲気中での加熱においてカーボンの還元作用により発生した酸素欠損を有し、前記酸素欠損に窒素がドープされたチタン酸リチウムナノ粒子。
Lithium titanate nanoparticles that are crystallized by heating a precursor of lithium titanate nanoparticles in a nitrogen atmosphere,
Lithium titanate nanoparticles having oxygen vacancies generated by the reduction action of carbon in heating in the nitrogen atmosphere, and wherein the oxygen vacancies are doped with nitrogen.
旋回する反応器内において、チタン源とリチウム源を含む溶液にずり応力と遠心力を加えて反応させてチタン酸リチウムナノ粒子の前駆体を製造し、この前駆体を窒素雰囲気中で加熱して生成した請求項1に記載のチタン酸リチウムナノ粒子。   In a rotating reactor, a solution containing a titanium source and a lithium source is reacted by applying shear stress and centrifugal force to produce a precursor of lithium titanate nanoparticles, and the precursor is heated in a nitrogen atmosphere. The produced lithium titanate nanoparticles according to claim 1. 前記請求項1または請求項2に記載のチタン酸リチウムナノ粒子をカーボンに分散担持させたことを特徴とするチタン酸リチウムナノ粒子とカーボンの複合体。   A composite of lithium titanate nanoparticles and carbon, wherein the lithium titanate nanoparticles according to claim 1 or 2 are dispersed and supported on carbon. 前記カーボンがグラファイトフラグメントのビルディングブロックであることを特徴とする請求項1〜請求項3のいずれか1項に記載のチタン酸リチウムナノ粒子とカーボンの複合体。   The composite of lithium titanate nanoparticles and carbon according to any one of claims 1 to 3, wherein the carbon is a building block of a graphite fragment. 前記請求項4に記載のチタン酸リチウムナノ粒子とカーボンの複合体を含有する電極。   An electrode containing the lithium titanate nanoparticles and carbon composite according to claim 4. 前記請求項5に記載の電極を備えた電気化学素子。   An electrochemical device comprising the electrode according to claim 5. 前記請求項5に記載の電極を負極に用い、分極性電極を正極に用いたことを特徴とする電気化学キャパシタ。   6. An electrochemical capacitor using the electrode according to claim 5 as a negative electrode and a polarizable electrode as a positive electrode. チタン酸リチウムナノ粒子の前駆体を窒素雰囲気中で加熱して結晶化させるチタン酸リチウムナノ粒子の製造方法であって、
前記窒素雰囲気中での加熱においてカーボンの還元作用により酸素欠損を発生させ、
この酸素欠損に窒素をドープさせるチタン酸リチウムナノ粒子の製造方法。
A method for producing lithium titanate nanoparticles, wherein the precursor of lithium titanate nanoparticles is crystallized by heating in a nitrogen atmosphere,
Oxygen deficiency is generated by the reducing action of carbon in the heating in the nitrogen atmosphere,
A method for producing lithium titanate nanoparticles in which nitrogen is doped into the oxygen deficiency.
旋回する反応器内において、チタン源とリチウム源を含む溶液にずり応力と遠心力を加えて反応させてチタン酸リチウムナノ粒子の前駆体を製造し、この前駆体を窒素雰囲気中で加熱してチタン酸リチウムナノ粒子を生成することを特徴とする請求項8に記載のチタン酸リチウムナノ粒子の製造方法。   In a rotating reactor, a solution containing a titanium source and a lithium source is reacted by applying shear stress and centrifugal force to produce a precursor of lithium titanate nanoparticles, and the precursor is heated in a nitrogen atmosphere. The method for producing lithium titanate nanoparticles according to claim 8, wherein lithium titanate nanoparticles are generated. 前記反応器内において、反応物と共に反応抑制剤を含む溶液にずり応力と遠心力を加えて反応させることを特徴とする請求項9に記載のチタン酸リチウムナノ粒子の製造方法。

The method for producing lithium titanate nanoparticles according to claim 9, wherein in the reactor, a solution containing a reaction inhibitor together with a reaction product is subjected to a reaction by applying a shear stress and a centrifugal force.

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