JP4275881B2 - Ultrasonic chemical production method of VOPO4 · 2H2O and application to positive electrode material of lithium secondary battery - Google Patents

Ultrasonic chemical production method of VOPO4 · 2H2O and application to positive electrode material of lithium secondary battery Download PDF

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JP4275881B2
JP4275881B2 JP2001353551A JP2001353551A JP4275881B2 JP 4275881 B2 JP4275881 B2 JP 4275881B2 JP 2001353551 A JP2001353551 A JP 2001353551A JP 2001353551 A JP2001353551 A JP 2001353551A JP 4275881 B2 JP4275881 B2 JP 4275881B2
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vopo
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ナムギュ パク
スンホ ジャン
クァンソン リュ
ヨンジュン パク
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G31/00—Compounds of vanadium
    • C01G31/02—Oxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
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    • 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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Description

【０００１】
【発明の属する技術分野】
本発明は、ＶＯＰＯ4・２Ｈ2Ｏの製造方法に関し、特に超音波化学的方法によるＶＯＰＯ4・２Ｈ2Ｏの製造方法に関する。
【０００２】
【従来の技術】
リチウム二次電池は、充放電が可能なエネルギー貯蔵装置であって、小型の電子機器の電源に用いられている。近年、充放電容量は大きくて、重量は軽い二次電池の開発が活発に進められている。現在リチウム二次電池の正極物質には、主にＬｉＣｏＯ2を用いているが、材料コストが非常に高いことが問題点である。このような問題点を解決するための代案としてＬｉＮｉＯ2またはＬｉＭｎ2Ｏ4物質が提示されたことがあるが、合成が容易ではないという問題、または充放電回数に応じて充放電容量が減少するというなどの新しい問題点が生じている。したがって高い電圧を有しながら充放電特性の優れた低コストの新しい物質の開発の必要性が望まれている。
【０００３】
これと関連して、最近研究されている非晶質Ｖ2Ｏ5キセロゲルは、高容量の特性を示すが、平均電圧が低いという問題点を有している。これに対し、金属−酸素間のイオン結合特性を強化させる場合、平均電圧を向上させることが可能であるという研究結果が報告されたことがある(K.S.Nanjundaswamy、A.K.Padhi、J.B.Goodenough、S.Okada、H.Ohtsuka、H.Arai、and J.Yamaki、Solid State Ionics、92、1 (1996); C.Masquelier、A.K.Padhi、K.S.Nanjundaswamy、and J.B.Goodenough、J.Solid State Chem.、135、228 (1998))。
【０００４】
金属−酸素間イオン結合特性を強化させる方法の一つには、（ＰＯ4）3-、（ＳＯ4）2-、（ＡｓＯ4）3-のような共有結合特性を有する物質を置換することである。このうち（ＳＯ4）2-がバナジウム酸化物に置換されたＶＯＳＯ4をリチウム二次電池に適用する場合、Ｖ4+／Ｖ3+酸化−還元による低い電圧が予想され、ＶＯＡｓＯ4は、Ｖ5+／Ｖ4+酸化−還元により高い電圧が予想されるが、高い質量による理論容量の減少と砒素の有害性のような短所を持っている。これに対し、ＶＯＰＯ4は、環境的に安定し、高い電圧と相対的に低い質量による高い理論容量が期待されるという長所も持っている。
【０００５】
これと関連して、二つの水分子を含むＶＯＰＯ4・２Ｈ2Ｏ化合物は、既に１９６５年に知られた物質であって、今まで知られた製造方法により結晶性を有するＶ2Ｏ5粉末とＨ3ＰＯ4水溶液を２４時間以上還流して製造する方法が知られている(G.Ladwig、Z.Anorg.Allg.Chem.、338、p 266 (1965))。しかし、このような方法は、２４時間以上の長時間の反応時間が必要であるのみでなく、粒子も０．０１〜０．２５ｍｍと大きいために、今まで主に触媒材料として応用されており、リチウム二次電池の正極材料に応用されていないというのが実状である。また、"Redox intercalation of alkali metals into vanadyl phosphate dihydrate(A.Chauvel 他.、Material Chemistry and Physics、40、pp.207-211、1995)でもＶＯＰＯ4・２Ｈ2Ｏの製造方法と、製造されたＶＯＰＯ4・２Ｈ2Ｏの層間にアルカリ金属イオンを挿入させた化合物の構造が開示されているが、前述したことと同様に、長時間に亘る還流法によって製造し、また製造されたＶＯＰＯ4・２Ｈ2Ｏも粒子の大きさが１０μｍ以上と大きいことが明らかになった。
【０００６】
また、前述したように現在商用化されているリチウム二次電池の正極物質のＬｉＣｏＯ2は、高い酸化−還元電位と長期的な充放電安定性を有するが、原料単価が高いという問題点のために、これを代替することのできる安いながら充放電特性に優れた材料の開発が要求されている。
【０００７】
【発明が解決しようとする課題】
そこで、本発明は、前述のような従来の技術の問題点に鑑みてなされたものであって、反応時間を非常に短縮させながらより小さい粒子の大きさを有するＶＯＰＯ4・２Ｈ2Ｏの新しい製造方法を提供することにその目的がある。
【０００８】
また、本発明は、前述のような新しい製造方法によって製造されたＶＯＰＯ4・２Ｈ2Ｏを含んで製造されたリチウム二次電池の正極物質を提供することにその目的がある。
【０００９】
【課題を解決するための手段】
前述のような目的を達成するために、本発明者らは鋭意研究を重ねた結果、超音波化学的方法を利用してＶＯＰＯ4・２Ｈ2Ｏを製造する場合、前述のような問題点を解決することができるということに着目して本発明を完成することに至った。
【００１０】
本発明は上記目的を達成するため、Ｖ2Ｏ5、Ｈ3ＰＯ4、及びＨ2Ｏの混合溶液を超音波処理してＶＯＰＯ4・２Ｈ2Ｏを製造する方法を提供する。この時、前述の製造方法においてＶ2Ｏ5：Ｈ3ＰＯ4：Ｈ2Ｏのモル比は、１：４０〜５０：５００〜６１０であるものが好ましい。特に、燐酸のモル比がＶ2Ｏ5の４０を越えない場合、製造されたＶＯＰＯ4・２Ｈ2Ｏが二次電池用正極物質として有用な特性を有し難い。前述の製造方法において、超音波処理の強さは、７０〜１００Ｗ／ｃｍ2とすることが好ましく、時間は１０〜１５分程度が好適である。
【００１１】
また、本発明は上記目的を達成するため、前述のＶ2Ｏ5：Ｈ3ＰＯ4：Ｈ2Ｏのモル比を１：４０〜５０：５００〜６１０で混合する工程と、前述の混合溶液を超音波処理する工程と、超音波処理して得られた物を洗浄した後、減圧ろ過させる工程と、ろ過して得られた物を常温で乾燥及び回収する工程とを含んでなるＶＯＰＯ4・２Ｈ2Ｏの製造方法を提供する。
【００１２】
さらに、本発明は前述の製造方法によって製造されたＶＯＰＯ4・２Ｈ2Ｏはリチウム二次電池の正電極用として使用することに非常に好適な特性を有しており、ＶＯＰＯ4・２Ｈ2Ｏのそのような用途を提供する。
【００１３】
また、本発明は上記目的を達成するため、Ｖ2Ｏ5、Ｈ3ＰＯ4、及びＨ2Ｏの混合溶液を超音波処理して製造したＶＯＰＯ4・２Ｈ2Ｏと、アセチレンブラックと、ポリ四塩化エチレンとが、各々６０〜８０重量％：１５〜２５重量％：５〜１５重量％で混合されたリチウム二次電池の正電極用組成物を提供する。
【００１４】
【発明の実施の形態】
以下本発明の構成を下記の実施例を通してより詳細に説明する。
【００１５】
実施例１：超音波化学的方法によるＶＯＰＯ 4 ・２Ｈ 2 Ｏの製造
まず、２ｇの結晶性Ｖ2Ｏ5をＨ3ＰＯ4水溶液（Ｈ3ＰＯ4を２６．７５ｍｌ及び蒸溜水を１０８．６ｍｌの混合物)と混合した。この時各成分のＶ2Ｏ5：Ｈ3ＰＯ4：Ｈ2Ｏのモル比は、１：５０：６０４にした。前述の溶液を混合する時、各成分のモル比は、１：４０〜５０：５００〜６１０の範囲が好適であり、燐酸のモル比が４０以下である場合、二次電池用の正極物質として有用なＶＯＰＯ4・２Ｈ2Ｏを得難いということは上記した通りである。
【００１６】
前述の混合溶液を１３ｍｍ直径のチタン合金ホーン(titanium alloy horn)に入れた後６００Ｗ、２０ｋＨｚの超音波発生装置を利用して約７０〜１００Ｗ／ｃｍ2の強さで１０〜１５分間超音波処理した。超音波処理過程において溶液の温度は、次第に増加して最高約６０〜８０℃まで到達した。超音波過程中、約５〜７分程度経過して赤黄色Ｖ2Ｏ5沈殿溶液が薄い黄色のコロイド溶液に変化し、これからＶＯＰＯ4・２Ｈ2Ｏが生成されることが分かった。
【００１７】
超音波処理後の黄色沈殿物を減圧ろ過させながらアセトン溶媒で数回洗浄した。ろ過された粉末を空気中において常温で乾燥してＶＯＰＯ4・２Ｈ2Ｏ粉末を回収した。
【００１８】
本発明の実施例1によって製造されたＶＯＰＯ4・２Ｈ2ＯのＸ線回折度を図1に示す。各回折のピックを分析して、格子定数ａ＝０．６２ｎｍ、ｃ＝０．７４ｎｍを有する斜方晶系の１００％純粋なＶＯＰＯ4・２Ｈ2Ｏが形成されたことを確認した。また製造されたＶＯＰＯ4・２Ｈ2Ｏのフーリエ変換赤外線吸収分光度を図２に示す。１，０００ｃｍ-1領域のピックは典型的なＶＯＰＯ4・２Ｈ2Ｏに該当する。
【００１９】
本発明の実施例によって合成されたＶＯＰＯ4・２Ｈ2Ｏの透過電子顕微鏡写真を図３に示す。四角形状の粒子形態を有しながら１〜３μｍの粒子の大きさを有した。
【００２０】
実施例２：リチウム二次電池の正電極の製造
前述の実施例1の方法により製造されたＶＯＰＯ4・２Ｈ2Ｏ粉末、アセチレンブラック及びポリ四塩化エチレンを各々７０：２０：１０の重量比で混合して、すり鉢内で細かく擦って正電極を製造した。エチレンカーボネート（ＥＣ）：ジメチルカーボネート（ＤＭＣ）が５０：５０の体積比で混合された溶媒に溶解されている１Ｍ ＬｉＰＦ6を電解質とし、リチウム金属を負極とするスウェイジロック(Swagelok)形態のテストセルを製造して一定の電流密度下でＶＯＰＯ4・２Ｈ2Ｏ電極の電気化学的充放電特性を測定した。
【００２１】
図４は、実施例２によって製造されたＶＯＰＯ4・２Ｈ2Ｏを含むリチウム二次電池の４．３〜２Ｖ区間で０．１５Ｃ放電及び充電速度（電流＝２０．８ｍＡ／ｇ）下で得られた最初の放電及び充電曲線である。最初の放電曲線で見られるように、３．６Ｖで平均電圧を保持し、リチウムイオン1モル比がＶＯＰＯ4・２Ｈ2Ｏに挿入されることが分かる。これは１３５ｍＡｈ／ｇの放電容量に該当する。最初の充電曲線から放電容量と類似した充電容量が得られ、これからリチウムイオンが可逆的に反応していることが分かった。放電容量と平均電圧から本発明の一実施例によって製造されたＶＯＰＯ4・２Ｈ2Ｏのエネルギー密度は４８６Ｗｈ／ｋｇであった。
【００２２】
図５は、実施例２によって製造されたＶＯＰＯ4・２Ｈ2Ｏを含むリチウム二次電池の放電速度に応じた放電容量を示すグラフである。０．０３Ｃの低速放電と１０倍に該当する０．３Ｃの高速放電時、放電容量の差が顕著ではないことが見られ、これから本発明によって製造されたＶＯＰＯ4・２Ｈ2Ｏは、リチウムイオンの拡散速度が速い物質であることが分かる。
【００２３】
図６は、充放電回数に伴う放電容量の変化を示しており、充放電サイクルが反復されても放電容量は初期値から大きく外れなかった。これから本発明によって製造されたＶＯＰＯ4・２Ｈ2Ｏは優れたサイクル特性を有する物質であることが分かる。
【００２４】
本発明の技術思想は、上記好ましい実施例によって具体的に記述されたが、上記した実施例はその説明のためのものであって、その制限のためのものでないことに留意されるべきである。また、本発明の技術分野の通常の専門家であるならば、本発明の技術思想の範囲内で種々の実施例が可能であることを理解されるべきである。
【００２５】
【発明の効果】
上述したように本発明に係る超音波化学的方法を利用してＶＯＰＯ4・２Ｈ2Ｏを製造する場合、既存の長い反応時間（２４時間以上）により製造されるものを短時間で製造できるので非常に迅速かつ経済的な画期的な製造方法である。
【００２６】
また本発明に係る超音波化学的製造方法により製造されたＶＯＰＯ4・２Ｈ2Ｏは、粒子の大きさが１〜３μｍ程度であって既存の方法によって製造されたものに比べて非常に小さく、平均電圧３．６Ｖ、放電容量１３５ｍＡｈ／ｇ、及び安定した充放電寿命等リチウム二次電池の正極物質として非常に優れた特性を持っている。
【図面の簡単な説明】
【図１】本発明に係るＶＯＰＯ4・２Ｈ2Ｏ粉末のＸ線回折図である。
【図２】本発明に係るＶＯＰＯ4・２Ｈ2Ｏのフーリエ変換赤外線吸収分光図である。
【図３】本発明に係るＶＯＰＯ4・２Ｈ2Ｏの透過電子顕微鏡写真を示す図である。
【図４】本発明に係るＶＯＰＯ4・２Ｈ2Ｏの最初の放電及び充電曲線を示す図である。
【図５】本発明に係るＶＯＰＯ4・２Ｈ2Ｏの放電速度に応じた放電容量の比較図である。
【図６】本発明に係るＶＯＰＯ4・２Ｈ2Ｏの放電回数に伴う放電容量変化図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing VOPO 4 .2H 2 O, and more particularly to a method for producing VOPO 4 .2H 2 O by an ultrasonic chemical method.
[0002]
[Prior art]
Lithium secondary batteries are energy storage devices that can be charged and discharged, and are used as power sources for small electronic devices. In recent years, the development of secondary batteries with large charge / discharge capacity and light weight has been actively promoted. Currently, LiCoO 2 is mainly used as the positive electrode material of the lithium secondary battery, but the problem is that the material cost is very high. LiNiO 2 or LiMn 2 O 4 materials have been presented as an alternative to solve such problems, but the problem is that synthesis is not easy, or the charge / discharge capacity decreases according to the number of charge / discharge cycles. There are new problems such as. Therefore, it is desired to develop a new low-cost material having a high voltage and excellent charge / discharge characteristics.
[0003]
In this connection, the recently studied amorphous V 2 O 5 xerogel exhibits high capacity characteristics but has a problem of low average voltage. On the other hand, research results have reported that the average voltage can be improved when the metal-oxygen ionic bond characteristics are enhanced (KSNanjundaswamy, AKPadhi, JBGoodenough, S. Okada, H. Ohtsuka, H.Arai, and J.Yamaki, Solid State Ionics, 92, 1 (1996); C. Masquelier, AKPadhi, KSNanjundaswamy, and JBGoodenough, J. Solid State Chem., 135, 228 (1998)).
[0004]
One way to enhance the metal-oxygen ionic bond properties is to substitute a material with covalent properties such as (PO 4 ) 3− , (SO 4 ) 2− , (AsO 4 ) 3− It is. When applying these the (SO 4) VOSO 4 to 2 is replaced with vanadium oxide in a lithium secondary battery, V 4+ / V 3+ oxidation - low voltage by reduction is expected, VOAsO 4 is, V 5+ / V 4+ oxidation - but higher voltage reduction is expected to have disadvantages, such as hazard reduction and arsenic of the theoretical capacity due to high mass. On the other hand, VOPO 4 has the advantages that it is environmentally stable and a high theoretical capacity due to a high voltage and a relatively low mass is expected.
[0005]
In this connection, a VOPO 4 .2H 2 O compound containing two water molecules is a substance already known in 1965, and has a V 2 O 5 powder having crystallinity by a known production method. And an aqueous solution of H 3 PO 4 by refluxing for 24 hours or longer are known (G. Ladwig, Z. Anorg. Allg. Chem., 338, p 266 (1965)). However, such a method not only requires a long reaction time of 24 hours or more, but also has a large particle size of 0.01 to 0.25 mm, and thus has been mainly applied as a catalyst material until now. In fact, it is not applied to the positive electrode material of a lithium secondary battery. In addition, “Redox intercalation of alkali metals into vanadyl phosphate dihydrate (A. Chauvel et al., Material Chemistry and Physics, 40, pp.207-211, 1995) and a method for producing VOPO 4 .2H 2 O and the produced VOPO Although the structure of a compound in which an alkali metal ion is inserted between the layers of 4.2H 2 O is disclosed, the VOPO 4 · 2H produced by the reflux method over a long period of time as described above and produced It was revealed that 2 O also has a large particle size of 10 μm or more.
[0006]
Further, as described above, LiCoO 2 as a positive electrode material of a lithium secondary battery that is currently commercialized has a high oxidation-reduction potential and long-term charge / discharge stability, but has a problem that the raw material unit price is high. In addition, there is a demand for the development of a material that can be replaced by a low-cost material having excellent charge / discharge characteristics.
[0007]
[Problems to be solved by the invention]
Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and is a new VOPO 4 .2H 2 O having a smaller particle size while greatly reducing the reaction time. The purpose is to provide a manufacturing method.
[0008]
Another object of the present invention is to provide a positive electrode material of a lithium secondary battery manufactured by including VOPO 4 .2H 2 O manufactured by the new manufacturing method as described above.
[0009]
[Means for Solving the Problems]
In order to achieve the above-described object, the present inventors have conducted intensive research. As a result, when VOPO 4 .2H 2 O is produced using an ultrasonic chemical method, the above-described problems are not solved. It came to complete this invention paying attention to being able to solve.
[0010]
In order to achieve the above object, the present invention provides a method for producing VOPO 4 .2H 2 O by sonicating a mixed solution of V 2 O 5 , H 3 PO 4 and H 2 O. At this time, the molar ratio of V 2 O 5 : H 3 PO 4 : H 2 O in the above production method is preferably 1: 40-50: 500-610. In particular, when the molar ratio of phosphoric acid does not exceed 40 of V 2 O 5 , it is difficult for the manufactured VOPO 4 .2H 2 O to have useful characteristics as a positive electrode material for a secondary battery. In the above-described manufacturing method, the intensity of ultrasonic treatment is preferably 70 to 100 W / cm 2, and the time is preferably about 10 to 15 minutes.
[0011]
In order to achieve the above object, the present invention includes a step of mixing the aforementioned V 2 O 5 : H 3 PO 4 : H 2 O at a molar ratio of 1:40 to 50: 500 to 610, and the above mixed solution. VOPO 4 comprising a step of ultrasonically treating, a step of washing the product obtained by sonication and then filtering under reduced pressure, and a step of drying and collecting the product obtained by filtration at room temperature. Provide a method for producing 2H 2 O.
[0012]
Furthermore, the present invention is VOPO 4 · 2H 2 O manufactured by the manufacturing method described above has a very suitable properties to be used as the positive electrode of a lithium secondary battery, VOPO 4 · 2H 2 O Of such uses.
[0013]
Further, since the present invention is to achieve the above object, and V 2 O 5, H 3 PO 4, and H 2 O VOPO 4 · 2H 2 O to a mixed solution was prepared by sonication, and acetylene black, poly Provided is a composition for a positive electrode of a lithium secondary battery in which ethylene tetrachloride is mixed at 60 to 80 wt%: 15 to 25 wt%: 5 to 15 wt%, respectively.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in more detail through the following examples.
[0015]
Example 1: Production of VOPO 4 · 2H 2 O by sonochemical method First, 2 g of crystalline V 2 O 5 was added to an aqueous solution of H 3 PO 4 (26.75 ml of H 3 PO 4 and distilled water). 108.6 ml of the mixture). At this time, the molar ratio of V 2 O 5 : H 3 PO 4 : H 2 O of each component was 1: 50: 604. When mixing the aforementioned solution, the molar ratio of each component is preferably in the range of 1:40 to 50: 500 to 610, and when the molar ratio of phosphoric acid is 40 or less, as a positive electrode material for a secondary battery. As described above, it is difficult to obtain useful VOPO 4 .2H 2 O.
[0016]
The mixed solution is placed in a titanium alloy horn having a diameter of 13 mm and then subjected to ultrasonic treatment at an intensity of about 70 to 100 W / cm 2 for 10 to 15 minutes using an ultrasonic generator of 600 W and 20 kHz. did. During the sonication process, the temperature of the solution gradually increased to reach a maximum of about 60-80 ° C. About 5 to 7 minutes passed during the ultrasonic process, the red-yellow V 2 O 5 precipitation solution turned into a light yellow colloidal solution, and it was found that VOPO 4 .2H 2 O was produced therefrom.
[0017]
The yellow precipitate after sonication was washed several times with an acetone solvent while filtering under reduced pressure. The filtered powder was dried at room temperature in air to recover VOPO 4 .2H 2 O powder.
[0018]
FIG. 1 shows the X-ray diffraction degree of VOPO 4 .2H 2 O produced according to Example 1 of the present invention. Analysis of each diffraction pick confirmed the formation of orthorhombic 100% pure VOPO 4 .2H 2 O with lattice constants a = 0.62 nm and c = 0.74 nm. In addition, FIG. 2 shows the Fourier transform infrared absorption spectrum of the manufactured VOPO 4 .2H 2 O. The pick in the 1,000 cm −1 region corresponds to a typical VOPO 4 .2H 2 O.
[0019]
FIG. 3 shows a transmission electron micrograph of VOPO 4 .2H 2 O synthesized according to the example of the present invention. It had a particle size of 1 to 3 μm while having a rectangular particle form.
[0020]
Example 2: Production of positive electrode of lithium secondary battery 70:20:10 of VOPO 4 .2H 2 O powder, acetylene black and polytetrachloroethylene produced by the method of Example 1 above, respectively. The positive electrode was manufactured by mixing at a weight ratio of 2 and finely rubbing in a mortar. Swagelok test cell using 1M LiPF 6 dissolved in a solvent mixed with ethylene carbonate (EC): dimethyl carbonate (DMC) in a volume ratio of 50:50 as an electrolyte and lithium metal as a negative electrode. And the electrochemical charge / discharge characteristics of the VOPO 4 .2H 2 O electrode were measured under a constant current density.
[0021]
FIG. 4 is obtained under a 0.15 C discharge and a charging rate (current = 20.8 mA / g) in a 4.3 to 2 V section of a lithium secondary battery including VOPO 4 .2H 2 O manufactured according to Example 2. It is the first discharge and charge curve produced. As can be seen in the first discharge curve, it can be seen that the average voltage is maintained at 3.6 V and that a 1 molar ratio of lithium ions is inserted into VOPO 4 .2H 2 O. This corresponds to a discharge capacity of 135 mAh / g. From the initial charge curve, a charge capacity similar to the discharge capacity was obtained, and it was found that lithium ions reacted reversibly. The energy density of VOPO 4 .2H 2 O produced according to an embodiment of the present invention from the discharge capacity and the average voltage was 486 Wh / kg.
[0022]
FIG. 5 is a graph showing the discharge capacity according to the discharge rate of the lithium secondary battery containing VOPO 4 .2H 2 O manufactured according to Example 2. It can be seen that there is not a significant difference in discharge capacity between 0.03C low-speed discharge and 0.3C high-speed discharge corresponding to 10 times, and VOPO 4 · 2H 2 O produced from the present invention is lithium ion It can be seen that this is a substance with a high diffusion rate.
[0023]
FIG. 6 shows the change in discharge capacity with the number of charge / discharge cycles, and the discharge capacity did not deviate significantly from the initial value even when the charge / discharge cycle was repeated. From this, it can be seen that VOPO 4 .2H 2 O produced by the present invention is a substance having excellent cycle characteristics.
[0024]
Although the technical idea of the present invention has been specifically described by the above preferred embodiments, it should be noted that the above embodiments are for the purpose of illustration and not for the limitation. . In addition, it should be understood that various embodiments are possible within the scope of the technical idea of the present invention if the person is an ordinary expert in the technical field of the present invention.
[0025]
【The invention's effect】
As described above, when VOPO 4 · 2H 2 O is produced using the ultrasonic chemical method according to the present invention, an existing product produced with a long reaction time (24 hours or more) can be produced in a short time. It is a revolutionary manufacturing method that is very quick and economical.
[0026]
In addition, VOPO 4 .2H 2 O produced by the ultrasonic chemical production method according to the present invention has a particle size of about 1 to 3 μm and is very small compared to those produced by an existing method. It has very excellent characteristics as a positive electrode material of a lithium secondary battery, such as an average voltage of 3.6 V, a discharge capacity of 135 mAh / g, and a stable charge / discharge life.
[Brief description of the drawings]
FIG. 1 is an X-ray diffraction pattern of a VOPO 4 .2H 2 O powder according to the present invention.
FIG. 2 is a Fourier transform infrared absorption spectrum of VOPO 4 .2H 2 O according to the present invention.
FIG. 3 is a transmission electron micrograph of VOPO 4 .2H 2 O according to the present invention.
FIG. 4 is a diagram showing initial discharge and charge curves of VOPO 4 .2H 2 O according to the present invention.
FIG. 5 is a comparison diagram of discharge capacity according to discharge rate of VOPO 4 .2H 2 O according to the present invention.
FIG. 6 is a diagram showing changes in discharge capacity with the number of discharges of VOPO 4 .2H 2 O according to the present invention.

Claims (6)

Ｖ2Ｏ5、Ｈ3ＰＯ4、及びＨ2Ｏの混合溶液を超音波処理する工程を具えることを特徴とするＶＯＰＯ4・２Ｈ2Ｏの製造方法。A method for producing VOPO 4 .2H 2 O, comprising a step of ultrasonicating a mixed solution of V 2 O 5 , H 3 PO 4 , and H 2 O. 前記Ｖ2Ｏ5：Ｈ3ＰＯ4：Ｈ2Ｏのモル比が１：４０〜５０：５００〜６１０であることを特徴とする請求項１に記載の製造方法。The manufacturing method according to claim 1, wherein the molar ratio of V 2 O 5 : H 3 PO 4 : H 2 O is 1: 40-50: 500-610. 前記超音波処理の強さは７０〜１００Ｗ／ｃｍ2であり、時間は１０〜１５分とすることを特徴とする請求項１に記載の製造方法。  2. The manufacturing method according to claim 1, wherein the intensity of the ultrasonic treatment is 70 to 100 W / cm <2> and the time is 10 to 15 minutes. 前記製造方法が、
Ｖ2Ｏ5：Ｈ3ＰＯ4：Ｈ2Ｏを各々１：４０〜５０：５００〜６１０のモル比で混合する工程と、
前記混合溶液を超音波処理する工程と、
超音波処理をして得られた物を洗浄し、減圧ろ過する工程と、
ろ過して得られた物を常温で乾燥及び回収する工程と、
を含んでなることを特徴とする請求項１に記載の製造方法。The manufacturing method is
Mixing V 2 O 5 : H 3 PO 4 : H 2 O in a molar ratio of 1:40 to 50: 500 to 610, respectively;
Sonicating the mixed solution;
A step of washing and filtering under reduced pressure obtained by sonication;
A step of drying and collecting the material obtained by filtration at room temperature;
The manufacturing method of Claim 1 characterized by the above-mentioned. 請求項１から請求項４のいずれかに記載の製造方法によって製造されたリチウム二次電池の正電極用ＶＯＰＯ4・２Ｈ2Ｏであって、粒子の大きさが、１μｍ〜３μｍであることを特徴とする正電極用ＶＯＰＯ 4 ・２Ｈ 2 Ｏ。 A positive electrode for VOPO 4 · 2H 2 O of Lithium secondary battery produced by the production method as claimed in any one of claims 4, that the size of the particles is 1μm~3μm VOPO 4 · 2H 2 O for positive electrodes characterized by Ｖ2Ｏ5、Ｈ3ＰＯ4、およびＨ2Ｏの混合溶液を超音波処理して製造したＶＯＰＯ4・２Ｈ2Ｏと、アセチレンブラックと、ポリ四塩化エチレンとが、各々６０〜８０重量％：１５〜２５重量％：５〜１５重量％の割合で混合されたリチウム二次電池の正電極用組成物であって、前記ＶＯＰＯ 4 ・２Ｈ 2 Ｏの粒子の大きさが、１μｍ〜３μｍであることを特徴とする正電極用組成物。VOPO 4 .2H 2 O produced by ultrasonic treatment of a mixed solution of V 2 O 5 , H 3 PO 4 , and H 2 O, acetylene black, and polytetrachloride are each 60 to 80% by weight. A composition for a positive electrode of a lithium secondary battery mixed at a ratio of 15 to 25% by weight: 5 to 15% by weight, wherein the particle size of the VOPO 4 .2H 2 O is 1 μm to 3 μm. There is a composition for positive electrode.
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