JP2019053953A - Carbon black and method for manufacturing the same - Google Patents
Carbon black and method for manufacturing the same Download PDFInfo
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- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
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- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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Abstract
Description
本発明はリチウムイオン二次電池に代表される非水電解質二次電池の電極に導電助剤として用いられるカーボンブラック及びその製造方法、前記カーボンブラックを含む非水電解質二次電池用電極及びその製造方法、前記電極を含む非水電解質二次電池に関する。 The present invention relates to a carbon black used as a conductive auxiliary agent for an electrode of a nonaqueous electrolyte secondary battery represented by a lithium ion secondary battery, a method for producing the same, an electrode for a nonaqueous electrolyte secondary battery containing the carbon black, and a production thereof The present invention relates to a method and a non-aqueous electrolyte secondary battery including the electrode.
リチウムイオン二次電池などの非水電解質二次電池の正極及び負極には、活物質として正極には主に金属の複合酸化物が、負極には主に黒鉛などの炭素系材料が使用され、それぞれ導電助剤としてのカーボンブラックや黒鉛微粉末、および結着材を含むペーストを集電体である金属箔に塗布し、集電体上に電極層を形成するペースト型電極が用いられている。 For the positive electrode and negative electrode of a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, a metal composite oxide is mainly used for the positive electrode as an active material, and a carbon-based material such as graphite is mainly used for the negative electrode. A paste type electrode is used in which a paste containing carbon black or graphite fine powder as a conductive additive and a binder is applied to a metal foil as a current collector to form an electrode layer on the current collector. .
近年、リチウムイオン二次電池を採用した電気自動車が増えている。自動車用非水電解質二次電池の特性として重要なものに、単位時間あたりに流せる電流量の大きさを示す出力特性と、充放電を繰り返しても放電容量を維持できるサイクル特性がある。 In recent years, the number of electric vehicles that employ lithium ion secondary batteries has increased. Important characteristics of the non-aqueous electrolyte secondary battery for automobiles include an output characteristic indicating the amount of current that can flow per unit time and a cycle characteristic that can maintain the discharge capacity even after repeated charge and discharge.
非水電解質二次電池の出力特性を改善するためには、電池の内部抵抗をできるだけ低減させることが重要であり、そのために電極中の導電ネットワークを形成する導電助剤を電極材料全体に均一かつ高濃度に分散させることで電極抵抗を低下させる技術がある。カーボンブラックはストラクチャーと呼ばれる一次粒子が鎖状に繋がった構造を有しているので、ストラクチャーの凝集や切断を防いで、電極材料中に適度に分散させるために分散剤を使用する必要がある。特許文献１は、分散剤として窒素系界面活性剤を用いることで正極活物質と導電助剤である炭素材料とを均一に分散させる方法を開示している。また、特許文献２は、トリアジン誘導体等を分散剤として用いることで、正極活物質とバインダーと導電助剤である炭素材料を安定に分散させる方法を開示している。 In order to improve the output characteristics of the non-aqueous electrolyte secondary battery, it is important to reduce the internal resistance of the battery as much as possible. For this reason, the conductive auxiliary agent that forms the conductive network in the electrode is uniformly distributed throughout the electrode material. There is a technique for reducing electrode resistance by dispersing it at a high concentration. Since carbon black has a structure in which primary particles called a structure are connected in a chain form, it is necessary to use a dispersing agent in order to prevent the structure from agglomerating and cutting and to appropriately disperse it in the electrode material. Patent Document 1 discloses a method of uniformly dispersing a positive electrode active material and a carbon material that is a conductive additive by using a nitrogen-based surfactant as a dispersant. Patent Document 2 discloses a method of stably dispersing a positive electrode active material, a binder, and a carbon material as a conductive auxiliary agent by using a triazine derivative or the like as a dispersant.
一方、カーボンブラックの表面改質方法として、特許文献３は、オイルやプラスチック、ゴムなどに添加するカーボンブラックをフッ素処理することにより、マトリックスとの親和性を向上させる方法を開示している。また、特許文献４は、塗料、インキ、樹脂等に添加するカーボンブラックをフッ素と酸素とを所定割合で並存させてカーボンブラックの酸化処理を行うことにより、カーボンブラックの分散性を向上させる方法を開示している。 On the other hand, as a surface modification method for carbon black, Patent Document 3 discloses a method for improving affinity with a matrix by subjecting carbon black added to oil, plastic, rubber, or the like to fluorine treatment. Patent Document 4 discloses a method for improving the dispersibility of carbon black by performing an oxidation treatment of carbon black added to paints, inks, resins, etc. in a predetermined ratio of fluorine and oxygen. Disclosure.
また、特許文献５は、好ましくは酸素で希釈したフッ素ガスで親水化処理されたカーボンブラックやカーボン繊維などの炭素系導電材と電極活物質の混合物をフッ素樹脂存在下において上記フッ素樹脂が溶融する温度以上、上記電極活物質が熱分解しない温度以下で焼成することによって複合化した電極材料を用いることにより、高出力かつ高エネルギー密度のリチウム電池を作製する方法を開示している。 Patent Document 5 describes that a mixture of a carbon-based conductive material such as carbon black or carbon fiber and an electrode active material that has been hydrophilicized with a fluorine gas diluted with oxygen is preferably melted in the presence of the fluororesin. A method of producing a lithium battery having a high output and a high energy density by using an electrode material combined by firing at a temperature not lower than a temperature and not higher than a temperature at which the electrode active material is not thermally decomposed is disclosed.
導電助剤として用いられるカーボンブラックはペーストへの分散性が悪いことが知られている。そのため、分散剤が用いられる。しかし、特許文献６によれば、特許文献１に記載の界面活性剤は、一般的な正極活物質として用いられるコバルト酸リチウムを用いると電池反応時に分解が起こるためサイクル特性に劣るという問題点があることが指摘されている。また特許文献２に記載の化合物も分散性が不十分であり、決して酸化安定性に優れるわけでもないのでサイクル特性に問題が残ることが指摘されている。また、分散剤は電池にとっては不純物となる。 It is known that carbon black used as a conductive aid has poor dispersibility in paste. Therefore, a dispersant is used. However, according to Patent Document 6, the surfactant described in Patent Document 1 has a problem in that when lithium cobaltate used as a general positive electrode active material is used, decomposition occurs during battery reaction, resulting in poor cycle characteristics. It has been pointed out that there is. In addition, it has been pointed out that the compound described in Patent Document 2 also has a problem in cycle characteristics because the dispersibility is insufficient and the oxidation stability is not always excellent. Further, the dispersant becomes an impurity for the battery.
また、特許文献３および４には、炭素系材料をフッ素処理することにより分散状態が向上することが記載されており、特許文献５では、複合化された電極材料を得るための炭素系導電材を、酸素で希釈したフッ素ガスで処理することで親水化することが記載されているが、表面改質したカーボンブラックをリチウムイオン二次電池の電極の導電助剤として使用した場合の評価は特に記載されていなかった。 Patent Documents 3 and 4 describe that the dispersion state is improved by treating the carbon-based material with fluorine. Patent Document 5 discloses a carbon-based conductive material for obtaining a composite electrode material. Is treated with a fluorine gas diluted with oxygen. However, the evaluation when the surface-modified carbon black is used as a conductive aid for an electrode of a lithium ion secondary battery is described in particular. It was not listed.
したがって、本発明は、カーボンブラックに表面改質処理を行うことでペーストへの分散性を向上させて、未処理の場合に比べて非水電解質二次電池のサイクル特性を向上させることができる非水電解質二次電池の電極の導電助剤用のカーボンブラックの製造方法及び、その方法で得られたカーボンブラックを提供することを目的とする。 Therefore, the present invention improves the dispersibility in the paste by subjecting the carbon black to the surface modification treatment, and can improve the cycle characteristics of the nonaqueous electrolyte secondary battery as compared with the case of no treatment. It aims at providing the carbon black obtained by the manufacturing method of the carbon black for the conductive support agent of the electrode of a water electrolyte secondary battery, and the method.
本発明者等は、上記目的を達成すべく種々検討した結果、リチウムイオン二次電池等の非水電解質二次電池用電極の導電助剤として適したカーボンブラックを得るためには、フッ素により表面改質処理したカーボンブラックの表面のフッ素および酸素の元素比を適切な範囲に管理する必要があることが分かった。フッ素ガスの濃度を特定範囲に設定し、残部を不活性ガスとした処理ガスを使用する、特定温度におけるフッ素による表面改質処理（以下、「フッ素処理」という）後に、気体の水と接触させる後処理を行うことでこの元素比を制御することができ、フッ素処理したカーボンブラックを用いた電極を用いると、電池の内部抵抗を低くし、かつ電池のサイクル特性を向上させることができることを見出した。 As a result of various studies to achieve the above-mentioned object, the present inventors have found that carbon black suitable as a conductive aid for an electrode for a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery has been It was found that the elemental ratio of fluorine and oxygen on the surface of the modified carbon black needs to be controlled within an appropriate range. Use a treatment gas with the concentration of fluorine gas in a specific range and the remainder as an inert gas. After surface modification treatment with fluorine at a specific temperature (hereinafter referred to as “fluorine treatment”), contact with gaseous water It has been found that the element ratio can be controlled by performing post-treatment, and that the internal resistance of the battery can be lowered and the cycle characteristics of the battery can be improved by using an electrode using carbon black subjected to fluorine treatment. It was.
すなわち、本発明は、正極、負極、および電解質を有する非水電解質二次電池の導電助剤として用いられるカーボンブラックであって、ＢＥＴ比表面積が２０ｍ２／ｇ以上であって１００ｍ２／ｇ未満であり、ＸＰＳ分析により測定した、フッ素原子の炭素原子に対する割合、即ちＦ／Ｃ比が０．００２以上であって０．０２５未満であり、かつ、酸素原子の炭素原子に対する割合、即ちＯ／Ｃ比が０．０１以上であって０．１未満である前記カーボンブラックを提供する。 That is, the present invention is a carbon black used as a conductive auxiliary for a nonaqueous electrolyte secondary battery having a positive electrode, a negative electrode, and an electrolyte, and has a BET specific surface area of 20 m 2 / g or more and less than 100 m 2 / g. And the ratio of fluorine atoms to carbon atoms, that is, the F / C ratio is 0.002 or more and less than 0.025, and the ratio of oxygen atoms to carbon atoms, that is, O / O, measured by XPS analysis. The carbon black having a C ratio of 0.01 or more and less than 0.1 is provided.
また、本発明は、ＢＥＴ比表面積が２５ｍ２／ｇ以上であって９５ｍ２／ｇ以下のカーボンブラックを、１０℃から５０℃において、フッ素ガス及び不活性ガスからなる処理ガスと接触させるフッ素処理工程と、ここで、前記処理ガス中のフッ素ガスの濃度が０．０１〜５体積％であり、フッ素処理後のカーボンブラックを気体の水と接触させる後処理工程と、を含む、カーボンブラックの製造方法の製造方法も提供する。 Further, the present invention is that the 95 m 2 / g or less of carbon black comprising a BET specific surface area set at 25m 2 / g or more, at 50 ° C. from 10 ° C., fluorine treatment of contacting with the processing gas consisting of fluorine gas and inert gas And a post-treatment step in which the concentration of fluorine gas in the treatment gas is 0.01 to 5% by volume, and the fluorine-treated carbon black is brought into contact with gaseous water. A manufacturing method of the manufacturing method is also provided.
本発明により、カーボンブラックに表面改質処理を行うことで、未処理の場合に比べて非水電解質二次電池のサイクル特性を向上させることができる、非水電解質二次電池の電極の導電助剤用のカーボンブラックの製造方法及び、その方法で得られたカーボンブラックを提供することが可能となる。また、本発明によればカーボンブラックの電極作製用ペーストへの分散性を向上させることができる。 According to the present invention, it is possible to improve the cycle characteristics of the non-aqueous electrolyte secondary battery by performing surface modification treatment on the carbon black, compared to the case where the carbon black is not treated. It becomes possible to provide a method for producing carbon black for an agent and carbon black obtained by the method. Further, according to the present invention, the dispersibility of carbon black in the electrode preparation paste can be improved.
以下、本発明の実施態様について以下に説明する。なお、本発明の範囲は、これらの説明に拘束されることはなく、以下の例示以外についても、本発明の趣旨を損なわない範囲で適宜変更し、実施することができる。 Hereinafter, embodiments of the present invention will be described. It should be noted that the scope of the present invention is not limited by these descriptions, and can be changed and implemented as appropriate without departing from the spirit of the present invention other than the following examples.
本発明では、カーボンブラックに対して、フッ素処理工程を行い、さらに後処理工程を行う。フッ素処理を行う前のカーボンブラック（以下、未処理カーボンブラックと呼ぶことがある）のＢＥＴ比表面積は、２５ｍ２／ｇ以上９５ｍ２／ｇ以下であることが好ましく、３０ｍ２／ｇ以上７５ｍ２／ｇ以下であることがより好ましい。このようなカーボンブラックとしては、油を不完全燃焼させるオイルファーネス法により得られるファーネスブラック、アセチレンガスを熱分解させるアセチレン法により得られるアセチレンブラックなどが挙げられる。例えば、ＴＩＭＣＡＬ社からＳｕｐｅｒ Ｐ（商標）として市販されているカーボンブラックを使用することができる。なお、フッ素処理の前と後処理の後とで、ＢＥＴ比表面積は大きな変化をせず、通常は±１０％以内の変化にとどまる。従って、本発明の方法によるフッ素処理と後処理後のカーボンブラック（以下、処理後カーボンブラック又は表面改質カーボンブラックと呼ぶことがある）のＢＥＴ比表面積は、２０ｍ２／ｇ以上１００ｍ２／ｇ未満であり、好ましくは２５以上９５ｍ２／ｇ以下であり、３０ｍ２／ｇ以上７５ｍ２／ｇ以下である。なお、カーボンブラックのＢＥＴ比表面積は、ＡＳＴＭ Ｄ ３０３７に準拠した方法で測定される。 In the present invention, a fluorine treatment process is performed on the carbon black, and a post-treatment process is further performed. Before the carbon black performing fluorine process BET specific surface area (hereinafter, may be referred to as untreated carbon black) is preferably not more than 25 m 2 / g or more 95m 2 / g, 30m 2 / g or more 75 m 2 / G or less is more preferable. Examples of such carbon black include furnace black obtained by an oil furnace method in which oil is incompletely burned, and acetylene black obtained by an acetylene method in which acetylene gas is thermally decomposed. For example, carbon black commercially available as Super P ™ from TIMCAL can be used. It should be noted that the BET specific surface area does not change greatly before and after the fluorine treatment, and usually remains within ± 10%. Therefore, the BET specific surface area of carbon black after fluorine treatment and post-treatment by the method of the present invention (hereinafter sometimes referred to as post-treatment carbon black or surface-modified carbon black) is 20 m 2 / g or more and 100 m 2 / g. It is less than, Preferably it is 25 or more and 95 m < 2 > / g or less, and is 30 m < 2 > / g or more and 75 m < 2 > / g or less. The BET specific surface area of carbon black is measured by a method based on ASTM D 3037.
まず、本発明では、フッ素処理を行う前に、未処理カーボンブラックに吸着している水分を加熱や真空脱気により除去するのが好ましい。これは、水分が残存していると、フッ素と反応してフッ化水素を発生し、製造装置等に悪影響を与えかねないためである。 First, in the present invention, it is preferable to remove moisture adsorbed on the untreated carbon black by heating or vacuum degassing before the fluorine treatment. This is because if moisture remains, it reacts with fluorine to generate hydrogen fluoride, which may adversely affect the production apparatus and the like.
本発明のフッ素処理法では、カーボンブラックを、通常、円筒形の容器の中に仕込む。ここに、フッ素濃度が所定の範囲になるように調整した処理ガスを流通させることにより、フッ素化、即ちカーボンブラックの表面にフッ素原子を化学結合させてＣ−Ｆ結合を形成させる。容器材質は、金属材料であれば安全に処理が可能であるが、連続的な処理を行う上では、耐腐食性の観点からＳＵＳ３０４やＳＵＳ３１６といったステンレス鋼材料やニッケルが望ましい。 In the fluorine treatment method of the present invention, carbon black is usually charged into a cylindrical container. Here, by passing a processing gas adjusted so that the fluorine concentration is within a predetermined range, fluorination, that is, fluorine atoms are chemically bonded to the surface of carbon black to form C—F bonds. The container material can be safely processed as long as it is a metal material. However, from the viewpoint of corrosion resistance, stainless steel materials such as SUS304 and SUS316 and nickel are desirable for continuous processing.
フッ素処理における処理ガスは、フッ素ガスと不活性ガスからなる。処理ガス中のフッ素ガスの濃度は０．０１〜５体積％であり、０．０５〜４体積％であることが好ましい。フッ素ガス濃度がこの範囲にあると、後処理後のＦ／Ｃ比及びＯ／Ｃ比が所望の範囲にあるカーボンブラックを得ることができ、内部抵抗値を増加させることなく、良好なサイクル特性を持つ非水電解質二次電池が得られる。処理ガス中にはフッ素と不活性ガス以外のガス、例えば酸素、が混入しないことが好ましく、もし混入したとしても、混入したガスの濃度が１体積％以下であることが好ましい。例えば、処理ガス中に酸素が混入すると、後処理後のＯ／Ｃ比を所望のＯ／Ｃ比に制御することが困難となるうえ、カーボンブラックとの反応が急激に進行し、場合によっては粉塵爆発の可能性がある。 The treatment gas in the fluorine treatment is composed of fluorine gas and inert gas. The concentration of the fluorine gas in the processing gas is 0.01 to 5% by volume, and preferably 0.05 to 4% by volume. When the fluorine gas concentration is within this range, carbon black having the desired F / C ratio and O / C ratio after the post-treatment can be obtained, and good cycle characteristics can be obtained without increasing the internal resistance value. A non-aqueous electrolyte secondary battery having It is preferable that a gas other than fluorine and an inert gas, such as oxygen, is not mixed in the processing gas, and even if mixed, the concentration of the mixed gas is preferably 1% by volume or less. For example, when oxygen is mixed in the processing gas, it becomes difficult to control the O / C ratio after the post-treatment to a desired O / C ratio, and the reaction with the carbon black proceeds rapidly. Possible dust explosion.
処理温度が５０℃を超える高温では、想定以上のフッ素化の進行により爆発の危険性が伴ったり、１０℃未満の低温では、冷却状態を作り出すために冷却のための装置やエネルギーが必要になったりとコスト面が課題となるため、室温付近での処理が望ましい。ただし、カーボンブラックとフッ素との接触時に発熱がある場合には、反応の制御のため、冷却水等を用いて、装置を冷却してもよい。 When the processing temperature is higher than 50 ° C, there is a risk of explosion due to the progress of fluorination more than expected, and when the processing temperature is lower than 10 ° C, cooling equipment and energy are required to create a cooling state. Since the cost is a problem, it is desirable to perform the treatment at around room temperature. However, in the case where heat is generated at the time of contact between carbon black and fluorine, the apparatus may be cooled using cooling water or the like for controlling the reaction.
処理時間に関しては、カーボンブラックとフッ素が満遍なく接触するために十分な時間が必要で、１０分以上を確保することが望ましく、３０分以上であることがさらに望ましい。長すぎる場合には、導電助剤としての性能に影響はないが、生産効率が低下するため、２時間以内であることが望ましい。また、フッ素処理後、カーボンブラックに物理吸着したフッ素、つまり表面改質に寄与していないフッ素を可能な限り除去するため、真空状態にし、脱気することが好ましい。 Regarding the treatment time, sufficient time is required for the carbon black and fluorine to uniformly contact each other, and it is desirable to ensure 10 minutes or more, and more desirably 30 minutes or more. If it is too long, there is no effect on the performance as a conductive additive, but the production efficiency is lowered, so that it is preferably within 2 hours. In addition, after the fluorine treatment, it is preferable to deaerate in a vacuum state in order to remove as much as possible the fluorine physically adsorbed on the carbon black, that is, fluorine not contributing to the surface modification.
処理圧力は特に制限されないが、安全性の観点からは７００Ｔｏｒｒ（９３．３ｋＰａ）以下であるのが好ましく、５００Ｔｏｒｒ（６６．７ｋＰａ）以下であるのがより好ましい。また十分な反応速度を得るために、１０Ｔｏｒｒ（１．３ｋＰａ）以上であることが好ましく、５０Ｔｏｒｒ（６．７ｋＰａ）以上であるのがより好ましい。好ましい処理ガスの流量は反応装置の大きさや構造によって異なるため、適宜調整すればよい。 The processing pressure is not particularly limited, but is preferably 700 Torr (93.3 kPa) or less, more preferably 500 Torr (66.7 kPa) or less from the viewpoint of safety. In order to obtain a sufficient reaction rate, it is preferably 10 Torr (1.3 kPa) or more, and more preferably 50 Torr (6.7 kPa) or more. Since the preferable flow rate of the processing gas varies depending on the size and structure of the reaction apparatus, it may be appropriately adjusted.
フッ素処理後、カーボンブラックを、気体の水、例えば所定の湿度を含む大気や、水蒸気に暴露することで、後処理工程を行う。後処理工程は１０〜３０℃で行うことができるが、加熱せずに、周囲温度や常温で処理することができる。また、相対湿度で３０〜８０％の大気に暴露する場合は、２時間以上４８時間以内の処理を行えば良く、相対湿度１００％の水蒸気で暴露する場合には、３０分以上２時間以内の処理を行えば良い。 After the fluorine treatment, the carbon black is exposed to gaseous water, for example, air containing a predetermined humidity or water vapor to perform a post-treatment process. The post-treatment step can be performed at 10 to 30 ° C., but can be performed at ambient temperature or normal temperature without heating. In addition, when exposed to the atmosphere of 30 to 80% at a relative humidity, the treatment may be performed for 2 hours or more and 48 hours or less, and when exposed to a water vapor of 100% relative humidity for 30 minutes or more and 2 hours or less. What is necessary is just to process.
カーボンブラックの表面には、フッ素処理により、Ｃ−Ｆ基等が生成する。後処理工程では、Ｈ２Ｏの作用により、カーボンブラックの表面にあるＣ−Ｆ基が、Ｃ−ＯＦ基、Ｃ−ＯＨ基やＣＯＯＨ基などに変換され、表面が改質される。表面が改質されたカーボンブラックは、電極作製用のペーストへの分散性が、改質前に比べて向上すると考えられる。この変換は、後処理工程終了後１時間程度で完了すると推測される。但し、カーボンブラック中の一部のＣ−Ｆ基は、フッ素原子が結合する炭素原子の他の炭素原子との結合状況の違いなどにより、ＦがＣに強固に結合しており、Ｈ２Ｏと反応せずに残存する。
なお、後処理工程にて生成するフッ化水素は、その後、真空脱気して、除去することができる。
A C—F group or the like is generated on the surface of carbon black by fluorine treatment. In the post-treatment step, the C—F group on the surface of the carbon black is converted into a C—OF group, a C—OH group, a COOH group, or the like by the action of H 2 O, and the surface is modified. It is considered that the carbon black whose surface is modified has improved dispersibility in the paste for electrode preparation as compared with that before the modification. This conversion is estimated to be completed in about one hour after the end of the post-processing step. However, some of the C-F group in the carbon black, due to differences in binding conditions with other carbon atoms of the carbon atoms to which fluorine atoms are bonded, are firmly bonded to F is C, H 2 O Remains without reacting.
Note that hydrogen fluoride generated in the post-treatment step can be removed by vacuum degassing thereafter.
このとき、後処理工程後の処理後カーボンブラックの表面のＸＰＳ（Ｘ線光電子分光）分析により測定した、フッ素原子の炭素原子に対する割合、即ちＦ／Ｃ比は０．００２以上０．０２５未満であり、０．００５以上０．０２以下が望ましい。また、酸素原子の炭素原子に対する割合、即ちＯ／Ｃ比は０．０１以上０．１未満であり、０．０２以上０．０８未満であることが望ましい。Ｆ／Ｃ比とＯ／Ｃ比が上記の範囲内であれば、フッ素や炭素に由来する抵抗の上昇を抑制しつつ、電極作製用のペーストへの分散性が向上して、カーボンブラックがネットワークを形成しやすくなる。 At this time, the ratio of fluorine atoms to carbon atoms, that is, the F / C ratio, measured by XPS (X-ray photoelectron spectroscopy) analysis on the surface of the post-treatment carbon black after the post-treatment step is 0.002 or more and less than 0.025. Yes, 0.005 or more and 0.02 or less are desirable. Further, the ratio of oxygen atoms to carbon atoms, that is, the O / C ratio is 0.01 or more and less than 0.1, and preferably 0.02 or more and less than 0.08. If the F / C ratio and the O / C ratio are within the above ranges, the dispersibility in the paste for electrode preparation is improved while suppressing the increase in resistance derived from fluorine and carbon, and carbon black is a network. It becomes easy to form.
後処理工程後の処理後カーボンブラックのＦ／Ｃ比とＯ／Ｃ比が高く、カーボンブラックの表面にフッ素原子や酸素原子が多すぎる場合、電池の内部抵抗が上昇し、電池のサイクル特性が悪化する。その原因は明らかではないが、本発明者らは、以下のように推測する。例えば、カーボンブラックの表面のフッ素原子や酸素原子が、不純物となり、カーボンブラックの形成するネットワークにおいて、カーボンブラックとカーボンブラックの間の接触抵抗が高くなることが考えられる。また、フッ素原子や酸素原子が多すぎる場合、過度のフッ素化反応により、カーボンブラックの縮合ベンゼン環が破壊された結果、カーボンブラック上のπ電子の移動が阻害され、カーボンブラック自体の導電性が悪化することが考えられる。 If the F / C ratio and O / C ratio of the carbon black after treatment after the post-treatment process is high and there are too many fluorine atoms or oxygen atoms on the surface of the carbon black, the internal resistance of the battery will increase, and the cycle characteristics of the battery will Getting worse. Although the cause is not clear, the present inventors presume as follows. For example, it is conceivable that fluorine atoms and oxygen atoms on the surface of carbon black become impurities, and in the network formed by carbon black, the contact resistance between carbon black and carbon black increases. In addition, when there are too many fluorine atoms or oxygen atoms, the condensed benzene ring of carbon black is destroyed by excessive fluorination reaction. As a result, the movement of π electrons on carbon black is inhibited, and the conductivity of carbon black itself is reduced. It is possible to get worse.
つぎに、本発明のカーボンブラックを用いた非水電解質二次電池について述べる。非水電解質二次電池用電解液と、リチウムイオンやナトリウムイオンを始めとするアルカリ金属イオン、又はアルカリ土類金属イオンが可逆的に挿入−脱離可能な負極材料と、リチウムイオンやナトリウムイオンを始めとするアルカリ金属イオン、又はアルカリ土類金属イオンが可逆的に挿入−脱離可能な正極材料を用いる電気化学ディバイスを非水電解質二次電池と呼ぶ。 Next, a non-aqueous electrolyte secondary battery using the carbon black of the present invention will be described. Non-aqueous electrolyte secondary battery electrolyte solution, negative electrode material capable of reversibly inserting and removing alkali metal ions such as lithium ions and sodium ions, or alkaline earth metal ions, lithium ions and sodium ions An electrochemical device using a positive electrode material into which alkali metal ions or alkaline earth metal ions can be reversibly inserted and removed is called a non-aqueous electrolyte secondary battery.
本発明の非水電解質二次電池は、本発明の処理後カーボンブラックを用いることが特徴であり、その他の構成部材には一般の非水電解質二次電池に使用されているものが用いられる。即ち、リチウムの吸蔵及び放出が可能な正極及び負極、金属箔からなる集電体、セパレータ、容器等から成る。 The nonaqueous electrolyte secondary battery of the present invention is characterized by using the treated carbon black of the present invention, and the other components used are those used in general nonaqueous electrolyte secondary batteries. That is, it consists of positive and negative electrodes capable of inserting and extracting lithium, a current collector made of metal foil, a separator, a container, and the like.
負極としては、特に限定されないが、リチウムイオンやナトリウムイオンを始めとするアルカリ金属イオン、又はアルカリ土類金属イオンが可逆的に挿入−脱離可能な材料が用いられ、正極としては、特に限定されないが、リチウムイオンやナトリウムイオンを始めとするアルカリ金属イオン、又はアルカリ土類金属イオンが可逆的に挿入−脱離可能な材料が用いられる。 The negative electrode is not particularly limited, but a material capable of reversibly inserting and desorbing alkali metal ions such as lithium ions and sodium ions or alkaline earth metal ions is used, and the positive electrode is not particularly limited. However, materials in which alkali metal ions such as lithium ions and sodium ions or alkaline earth metal ions can be reversibly inserted and removed are used.
本発明の処理後カーボンブラックを負極の導電助剤として用いる場合、リチウムイオンなどを吸蔵および放出することが可能な負極活物質、結着材、処理後カーボンブラックおよび分散媒を混合し、スラリー化したのち、集電体である金属箔へと塗布し、乾燥、加圧し、負極層を形成する。リチウムイオンなどを吸蔵および放出することが可能な種々の材料としては、例えば、カチオンがリチウムの場合、負極材料としてリチウム金属、リチウムと他の金属との合金及び金属間化合物や、人造黒鉛や天然黒鉛、活性炭などの炭素材料、金属酸化物、金属窒化物等が用いられる。 When carbon black after the treatment of the present invention is used as a conductive additive for the negative electrode, a negative electrode active material capable of occluding and releasing lithium ions, a binder, the treated carbon black and a dispersion medium are mixed to form a slurry. After that, it is applied to a metal foil as a current collector, dried and pressurized to form a negative electrode layer. Examples of various materials capable of inserting and extracting lithium ions include, for example, when the cation is lithium, lithium metal as an anode material, alloys and intermetallic compounds of lithium with other metals, artificial graphite and natural materials. Carbon materials such as graphite and activated carbon, metal oxides, metal nitrides and the like are used.
本発明の処理後カーボンブラックを正極の導電助剤として用いる場合、リチウムイオンなどを吸蔵および放出することが可能な正極活物質、結着材、処理後カーボンブラック、分散媒とを混合し、スラリー化したのち、集電体である金属箔へと塗布し、乾燥、加圧し、正極を形成する。また、スラリー化の前に、正極活物質と処理後カーボンブラック、導電助剤などを、ボールミルなどで乾式混合してもよい。リチウム電池及びリチウムイオン二次電池の場合、活物質としては、例えば、ＬｉＣｏＯ２、ＬｉＮｉＯ２、ＬｉＭｎＯ２、ＬｉＭｎ２Ｏ４等のリチウム含有遷移金属複合酸化物、それらのリチウム含有遷移金属複合酸化物のＣｏ、Ｍｎ、Ｎｉ等の遷移金属が複数混合したもの、それらのリチウム含有遷移金属複合酸化物の遷移金属の一部が他の遷移金属以外の金属に置換されたもの、オリビンと呼ばれるＬｉＦｅＰＯ４、ＬｉＣｏＰＯ４、ＬｉＭｎＰＯ４等の遷移金属のリン酸化合物、ＴｉＯ２、Ｖ２Ｏ５、ＭｏＯ３等の酸化物、ＴｉＳ２、ＦｅＳ等の硫化物等を用いられる。あるいはポリアセチレン、ポリパラフェニレン、ポリアニリン、及びポリピロール等の導電性高分子、活性炭、ラジカルを発生するポリマー、カーボン材料等が使用される。 When carbon black after treatment of the present invention is used as a conductive additive for the positive electrode, a positive electrode active material capable of occluding and releasing lithium ions, a binder, carbon black after treatment, and a dispersion medium are mixed, and slurry Then, it is applied to a metal foil as a current collector, dried and pressurized to form a positive electrode. Further, before the slurrying, the positive electrode active material, the treated carbon black, the conductive auxiliary agent, and the like may be dry-mixed with a ball mill or the like. In the case of a lithium battery and a lithium ion secondary battery, examples of the active material include lithium-containing transition metal composite oxides such as LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , and lithium-containing transition metal composite oxides A mixture of a plurality of transition metals such as Co, Mn, Ni, etc., a part of the transition metal of the lithium-containing transition metal composite oxide substituted with a metal other than the transition metal, LiFePO 4 called olivine , LiCoPO 4, phosphoric acid compound of a transition metal such as LiMnPO 4, oxides such as TiO 2, V 2 O 5, MoO 3, is used to TiS 2, sulfides such as FeS or the like. Alternatively, conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole, activated carbon, polymers that generate radicals, carbon materials, and the like are used.
正極層又は負極層の電極層中に含まれる導電助剤の量、すなわち、スラリー中の固体成分に占める導電助剤の量は、０．１〜２０質量％であることが好ましく、０．５〜１０質量％含むことがより好ましく、１〜８質量％含むことがさらに好ましい。 The amount of the conductive additive contained in the electrode layer of the positive electrode layer or the negative electrode layer, that is, the amount of the conductive additive in the solid component in the slurry is preferably 0.1 to 20% by mass, It is more preferable to contain 10 mass%, and it is more preferable to contain 1-8 mass%.
正極や負極材料に用いられる結着材としては、ポリテトラフルオロエチレン、ポリフッ化ビニリデン、ＳＢＲ樹脂等が用いられる。また、溶媒としてはＮ−メチル−２−ピロリドン（以降「ＮＭＰ」）などの有機溶媒、水などの水系溶媒などが用いられる。 As a binder used for the positive electrode or the negative electrode material, polytetrafluoroethylene, polyvinylidene fluoride, SBR resin, or the like is used. As the solvent, an organic solvent such as N-methyl-2-pyrrolidone (hereinafter “NMP”), an aqueous solvent such as water, and the like are used.
以下に本発明の実施例を比較例とともに挙げるが、本発明は以下の実施例に制限されるものではない。 Examples of the present invention are listed below together with comparative examples, but the present invention is not limited to the following examples.
［実施例１］
＜フッ素処理及び後処理後（以下「処理後」という）カーボンブラックの作製＞
未処理カーボンブラックとして、ＢＥＴ比表面積６２ｍ２／ｇのもの（Ｓｕｐｅｒ Ｐ Ｌｉ（商標），ＴＩＭＣＡＬ社製）を用い、容積５ＬのＳＵＳ３０４製容器に封入し、内部を真空引きし、カーボンブラックに吸着している水分を除去した。ここに、窒素で０．０５体積％に希釈したフッ素を２００Ｔｏｒｒ（２６．７ｋＰａ）封入し、その後３０分間にわたって総流量０．５ＳＬＭで流通させた。なお、上記の反応は室温（２５℃）で行った。流通終了後、容器内を窒素にて十分に置換した。その後、容器内を再び真空状態まで減圧し、一晩脱気することにより、カーボンブラックに吸着したフッ素を可能な限り除去した。続いて、容器内を大気圧まで復圧し、２４時間、大気（気温２５℃、相対湿度４５〜５０％）に曝した。これらの操作により得られた、処理後カーボンブラックはＸＰＳ（「ＰＨＩ ＶｅｒｓａＰｒｏｂｅ ＩＩ」、アルバックファイ社製、Ｘ線源：Ａｌ、Ｘ線：ＡｌＫα線（１４８６．６ｅＶ）、出力：２３．８Ｗ、ビーム径：１００μｍ）にてその表面組成を測定した。また、ＡＳＴＭ Ｄ ３０３７に準拠した方法でそのＢＥＴ比表面積を測定した。
[Example 1]
<Production of carbon black after fluorine treatment and after treatment (hereinafter referred to as "after treatment")
Untreated carbon black having a BET specific surface area of 62 m 2 / g (Super P Li (trademark), manufactured by TIMCAL) is enclosed in a 5 L SUS304 container, the inside is evacuated, and adsorbed on the carbon black Removed moisture. Here, 200 Torr (26.7 kPa) of fluorine diluted to 0.05% by volume with nitrogen was sealed, and then allowed to flow at a total flow rate of 0.5 SLM for 30 minutes. In addition, said reaction was performed at room temperature (25 degreeC). After the end of distribution, the inside of the container was sufficiently replaced with nitrogen. Thereafter, the inside of the container was again depressurized to a vacuum state and deaerated overnight to remove as much as possible the fluorine adsorbed on the carbon black. Subsequently, the inside of the container was restored to atmospheric pressure and exposed to the atmosphere (temperature 25 ° C., relative humidity 45-50%) for 24 hours. The treated carbon black obtained by these operations is XPS (“PHI VersaProbe II”, manufactured by ULVAC-PHI, X-ray source: Al, X-ray: AlKα ray (1486.6 eV), output: 23.8 W, beam The surface composition was measured at a diameter of 100 μm). Further, the BET specific surface area was measured by a method based on ASTM D 3037.
＜正極の作製＞
正極活物質として、ＬｉＮｉ１／３Ｃｏ１／３Ｍｎ１／３Ｏ２（ＮＣＭ）粉末及び実施例１で製造した処理後カーボンブラックを、ボールミルを用いて３０分間乾式混合し、結着材であるポリフッ化ビニリデン（以降「ＰＶＤＦ」）を予め溶解させたＮＭＰ中に均一に分散させ、混合し、さらに粘度調整用ＮＭＰを加え、ＮＣＭ合剤ペーストを調製した。このペーストをアルミニウム箔（集電体）上に塗布して、１００℃１時間乾燥し、ローラーで４ｋＮ／ｍ２で加圧を行った後に、所定のサイズに加工した試験用ＮＭＣ正極を得た。正極中の固形分比率は、ＮＣＭ：処理後カーボンブラック：ＰＶＤＦ＝８５：５：１０（質量比）とした。
<Preparation of positive electrode>
As a positive electrode active material, LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM) powder and the treated carbon black produced in Example 1 were dry-mixed for 30 minutes using a ball mill, and a binder was used. An NCM mixture paste was prepared by uniformly dispersing and mixing certain polyvinylidene fluoride (hereinafter referred to as “PVDF”) in NMP, mixing, and adding NMP for viscosity adjustment. This paste was applied onto an aluminum foil (current collector), dried at 100 ° C. for 1 hour, and pressurized with a roller at 4 kN / m 2 to obtain a test NMC positive electrode processed into a predetermined size. . The solid content ratio in the positive electrode was NCM: carbon black after treatment: PVDF = 85: 5: 10 (mass ratio).
＜黒鉛負極の作製＞
負極活物質として、黒鉛粉末を、結着材であるＰＶＤＦを予め溶解させたＮＭＰ中に均一に分散させ、混練機を用いて２０００ｒｐｍで２０分間混合し、さらに粘度調整用ＮＭＰを加え、黒鉛合剤ペーストを調製した。このペーストを銅箔（集電体）上に塗布して、５０℃で１時間乾燥し、ローラーで４ｋＮ／ｍ２で加圧を行った後に、所定のサイズに加工した試験用黒鉛負極を得た。負極中の固形分比率は、黒鉛粉末：ＰＶＤＦ＝９０：１０（質量比）とした。
<Preparation of graphite negative electrode>
As a negative electrode active material, graphite powder was uniformly dispersed in NMP in which PVDF as a binder was previously dissolved, mixed at 2000 rpm for 20 minutes using a kneader, and further NMP for viscosity adjustment was added. An agent paste was prepared. This paste was applied onto a copper foil (current collector), dried at 50 ° C. for 1 hour, pressurized with a roller at 4 kN / m 2 , and then a test graphite negative electrode processed into a predetermined size was obtained. It was. The solid content ratio in the negative electrode was graphite powder: PVDF = 90: 10 (mass ratio).
＜非水電解質二次電池の作製＞
上記の試験用ＮＣＭ正極と、試験用黒鉛負極と、セルロース製セパレータとを備えるアルミラミネート外装セル（容量３０ｍＡｈ）に、非水溶媒を含浸させ、非水電解質二次電池を得た。なお、非水溶媒としてエチレンカーボネート（以降「ＥＣ」）、プロピレンカーボネート（以降「ＰＣ」）、ジメチルカーボネート（以降「ＤＭＣ」）、エチルメチルカーボネート（以降「ＥＭＣ」）の体積比２：１：３：４の混合溶媒を用い、該溶媒中に溶質としてヘキサフルオロリン酸リチウム（以降「ＬｉＰＦ６」）を１．０ｍｏｌ／Ｌの濃度となるように溶解し、電解液を調製した。なお、上記の調製は、液温を２５℃に維持しながら行った。
<Preparation of nonaqueous electrolyte secondary battery>
An aluminum laminate outer cell (capacity 30 mAh) comprising the above test NCM positive electrode, test graphite negative electrode, and cellulose separator was impregnated with a nonaqueous solvent to obtain a nonaqueous electrolyte secondary battery. The volume ratio of ethylene carbonate (hereinafter “EC”), propylene carbonate (hereinafter “PC”), dimethyl carbonate (hereinafter “DMC”), and ethyl methyl carbonate (hereinafter “EMC”) as the non-aqueous solvent is 2: 1: 3. : 4 was used, and lithium hexafluorophosphate (hereinafter referred to as “LiPF 6 ”) was dissolved as a solute in the solvent to a concentration of 1.0 mol / L to prepare an electrolytic solution. In addition, said preparation was performed maintaining a liquid temperature at 25 degreeC.
＜電池評価＞
＜評価１：電池の内部抵抗の測定＞
実施例・比較例に係る非水電解質二次電池のそれぞれについて、以下の評価を実施した。
まず、作製したセルを用いて、２５℃の環境温度で、以下の条件でコンディショニングを実施した。すなわち、初回充放電として、充電上限電圧４．３Ｖ、０．１Ｃレート（３ｍＡ）で定電流定電圧充電し、放電終止電圧３．０Ｖまで０．２Ｃレート（６ｍＡ）定電流で放電を行い、その後、充電上限電圧４．３Ｖ、０．２Ｃレート（６ｍＡ）で定電流定電圧充電し、放電終止電圧３．０Ｖまで０．２Ｃレート（６ｍＡ）定電流で放電を行う充放電サイクルを３回繰り返した。その後電池の内部抵抗を測定した。表１には、各実施例および比較例における内部抵抗の測定結果を記載した。なお、表１に記載の内部抵抗の数値は、比較例１の内部抵抗を１００とした場合の相対値であり、低いほど好ましい。
<Battery evaluation>
<Evaluation 1: Measurement of battery internal resistance>
The following evaluation was implemented about each of the nonaqueous electrolyte secondary battery which concerns on an Example and a comparative example.
First, conditioning was performed using the fabricated cell at an environmental temperature of 25 ° C. under the following conditions. That is, as the first charge / discharge, the battery is charged at a constant current and constant voltage at a charging upper limit voltage of 4.3 V and a 0.1 C rate (3 mA), and discharged at a 0.2 C rate (6 mA) constant current up to a discharge end voltage of 3.0 V. Thereafter, charging / discharging cycle is performed three times by charging at a constant current / constant voltage at a charging upper limit voltage of 4.3V and a 0.2C rate (6 mA) and discharging at a constant current of 0.2C (6 mA) to a discharge end voltage of 3.0V. Repeated. Thereafter, the internal resistance of the battery was measured. Table 1 shows the measurement results of the internal resistance in each example and comparative example. In addition, the numerical value of internal resistance of Table 1 is a relative value when the internal resistance of the comparative example 1 is set to 100, and it is so preferable that it is low.
＜評価２：高温サイクル特性の測定＞
上記コンディショニングを実施後、５５℃の環境温度で充電上限電圧４．３Ｖ、３Ｃレート（９０ｍＡ）で定電流定電圧充電した後、放電終止電圧３．０Ｖまで３Ｃレート（９０ｍＡ）定電流で放電し、この充放電を１００サイクル繰り返した。１００サイクル目の放電容量の、初期（１サイクル目）の放電容量に対する割合をサイクル容量維持率とし、セルの高温サイクル特性を評価した。なお、表１に記載の１００サイクル後のサイクル特性の数値は、比較例１の１００サイクル後の放電容量維持率を１００とした場合の相対値であり、高いほど好ましい。
<Evaluation 2: Measurement of high-temperature cycle characteristics>
After performing the above conditioning, after charging at a constant current and constant voltage at an upper limit voltage of 4.3 V and a 3 C rate (90 mA) at an environmental temperature of 55 ° C., the battery is discharged at a constant current of 3 C (90 mA) to a discharge end voltage of 3.0 V. This charging / discharging was repeated 100 cycles. The ratio of the discharge capacity at the 100th cycle to the initial (first cycle) discharge capacity was defined as the cycle capacity retention rate, and the high temperature cycle characteristics of the cell were evaluated. In addition, the numerical value of the cycle characteristic after 100 cycles described in Table 1 is a relative value when the discharge capacity retention rate after 100 cycles of Comparative Example 1 is 100, and the higher the value, the more preferable.
［実施例２］
処理後カーボンブラックの作製に際し、使用した希釈フッ素の濃度を２体積％にし、フッ素との接触時間を１０分にした以外は、実施例１と同様の試験を行った。
［実施例３］
処理後カーボンブラックの作製に際し、使用した希釈フッ素の濃度を０．５体積％にした以外は、実施例１と同様の試験を行った。
［実施例４］
処理後カーボンブラックの作製に際し、使用した希釈フッ素の濃度を２体積％にした以外は、実施例１と同様の試験を行った。
［実施例５］
処理後カーボンブラックの作製に際し、使用した希釈フッ素の濃度を４体積％にした以外は、実施例１と同様の試験を行った。
[Example 2]
The same test as in Example 1 was performed except that the concentration of diluted fluorine used was 2% by volume and the contact time with fluorine was 10 minutes when producing carbon black after the treatment.
[Example 3]
The same test as in Example 1 was performed except that the concentration of diluted fluorine used was changed to 0.5% by volume in the production of carbon black after the treatment.
[Example 4]
The same test as in Example 1 was performed except that the concentration of diluted fluorine used was changed to 2% by volume in the production of carbon black after the treatment.
[Example 5]
The same test as in Example 1 was performed, except that the concentration of diluted fluorine used was changed to 4% by volume in the production of carbon black after the treatment.
［実施例６］
処理後カーボンブラックの作製に際し、希釈フッ素と接触させる際の圧力を５０Ｔｏｒｒ（６．７ｋＰａ）にした以外は、実施例５と同様の試験を行った。
［実施例７］
処理後カーボンブラックの作製に際し、希釈フッ素と接触させる際の圧力を５００Ｔｏｒｒ（６６．７ｋＰａ）にした以外は、実施例４と同様の試験を行った。
［実施例８］
処理後カーボンブラックの作製に際し、使用した希釈フッ素の濃度を４体積％にし、希釈フッ素と接触させる際の圧力を５００Ｔｏｒｒ（６６．７ｋＰａ）にした以外は、実施例４と同様の試験を行った。
[Example 6]
The same test as in Example 5 was performed except that the pressure when contacting with diluted fluorine was changed to 50 Torr (6.7 kPa) when producing carbon black after the treatment.
[Example 7]
In the production of carbon black after the treatment, the same test as in Example 4 was performed, except that the pressure when contacting with diluted fluorine was 500 Torr (66.7 kPa).
[Example 8]
In the production of carbon black after the treatment, the same test as in Example 4 was performed except that the concentration of diluted fluorine used was 4% by volume and the pressure when contacting with diluted fluorine was 500 Torr (66.7 kPa). .
［実施例９］
処理後カーボンブラックの作製に際し、未処理カーボンブラックとしてＢＥＴ比表面積４５ｍ２／ｇのカーボンブラック（Ｓｕｐｅｒ Ｃ４５（商標），ＴＩＭＣＡＬ社製）を用いた以外は、実施例１と同様の試験を行った。
［実施例１０］
処理後カーボンブラックの作製に際し、希釈フッ素と接触させる際の処理時間を９０分にした以外は、実施例９と同様の試験を行った。
［実施例１１］
処理後カーボンブラックの作製に際し、処理温度を４０℃にし、処理時間を１０分にした以外は、実施例２と同様の試験を行った。
［実施例１２］
処理後カーボンブラックの作製に際し、処理温度を４０℃にし、処理時間を１０分にし、後処理工程にて気体の水として、常温の水蒸気（相対湿度１００％の窒素ガス）を１時間供給した以外は、実施例２と同様の試験を行った。
[Example 9]
The same test as in Example 1 was performed except that carbon black having a BET specific surface area of 45 m 2 / g (Super C45 (trademark), manufactured by TIMCAL) was used as the untreated carbon black in the production of the treated carbon black. .
[Example 10]
The same test as in Example 9 was performed, except that the treatment time for contacting with diluted fluorine was set to 90 minutes when producing the carbon black after the treatment.
[Example 11]
The same test as in Example 2 was performed except that the processing temperature was set to 40 ° C. and the processing time was set to 10 minutes when producing the carbon black after the processing.
[Example 12]
In preparation of post-treatment carbon black, the treatment temperature was set to 40 ° C., the treatment time was set to 10 minutes, and water vapor at normal temperature (nitrogen gas with a relative humidity of 100%) was supplied for 1 hour as gaseous water in the post-treatment process. The same test as in Example 2 was performed.
［比較例１］
フッ素処理工程に代えて、フッ素を含まない窒素ガスを流通させた以外は、実施例１と同様の試験を行った。
［比較例２］
処理後カーボンブラックの作製に際し、使用した希釈フッ素の濃度を０．００５体積％にした以外は、実施例１と同様の試験を行った。
［比較例３］
処理後カーボンブラックの作製に際し、使用した希釈フッ素の濃度を７体積％にした以外は、実施例１と同様の試験を行った。
［比較例４］
処理後カーボンブラックの作製に際し、フッ素の濃度を４体積％にし、酸素の濃度を１０体積％とし窒素で希釈したガスを流通させる以外は、実施例１と同様の試験を行った。
[Comparative Example 1]
Instead of the fluorine treatment step, the same test as in Example 1 was performed except that nitrogen gas not containing fluorine was circulated.
[Comparative Example 2]
The same test as in Example 1 was performed, except that the concentration of diluted fluorine used was changed to 0.005% by volume in the production of carbon black after the treatment.
[Comparative Example 3]
The same test as in Example 1 was performed, except that the concentration of diluted fluorine used was changed to 7% by volume in the production of the carbon black after the treatment.
[Comparative Example 4]
In the production of carbon black after the treatment, the same test as in Example 1 was performed except that the concentration of fluorine was 4% by volume, the concentration of oxygen was 10% by volume, and a gas diluted with nitrogen was circulated.
［比較例５］
処理後カーボンブラックの作製に際し、希釈フッ素と接触させる際の処理温度を８０℃とした以外は、実施例１と同様の試験を行った。
［比較例６］
処理後カーボンブラックの作製に際し、後処理工程にて酸素ガスを供給した以外は、実施例１と同様の試験を行った。
［比較例７］
処理後カーボンブラックの作製に際し、後処理工程にて窒素ガスを供給した以外は、実施例１と同様の試験を行った。
［比較例８］
処理後カーボンブラックの作製に際し、未処理カーボンブラックとして実施例９で使用したカーボンブラックを用い、フッ素処理工程において、フッ素を含まない窒素ガスを流通させた以外は、実施例１と同様の試験を行った。
[Comparative Example 5]
The same test as in Example 1 was performed except that the treatment temperature when contacting with diluted fluorine was set to 80 ° C. in the production of carbon black after the treatment.
[Comparative Example 6]
The same test as in Example 1 was performed except that oxygen gas was supplied in the post-treatment process when producing the post-treatment carbon black.
[Comparative Example 7]
The same test as in Example 1 was performed except that nitrogen gas was supplied in the post-treatment process when producing the post-treatment carbon black.
[Comparative Example 8]
The same test as in Example 1 was performed except that the carbon black used in Example 9 was used as an untreated carbon black in the preparation of the treated carbon black, and nitrogen gas not containing fluorine was circulated in the fluorine treatment process. went.
実施例１〜１２の結果と比較例１〜８の結果より、フッ素濃度０．０５〜５体積％の範囲の希釈フッ素ガスとカーボンブラックとを接触させ、気体の水と接触させる後処理工程を行うことにより、ＸＰＳ分析により測定した、フッ素原子の炭素原子に対する割合、即ちＦ／Ｃ比が０．００１以上０．０２５未満であり、かつ、酸素原子の炭素原子に対する割合、即ちＯ／Ｃ比が０．１以上０．２未満であることを特徴とする処理後カーボンブラックを得られることがわかる。また、これらの範囲にある処理後カーボンブラックを用いて作製した非水電解質二次電池は、フッ素濃度が上記範囲外であるか又は酸素ガスを含む希釈フッ素による処理を施したカーボンブラックに比べて、内部抵抗値が低下しており、かつ高い放電容量維持率を維持していることがわかる。なお、ＸＰＳ分析により、実施例１〜１２の処理後カーボンブラックの表面には、Ｃ−ＯＦ基、Ｃ−ＯＨ基、又はＣＯＯＨ基の少なくとも一つの官能基が存在していたことがわかった。 From the results of Examples 1 to 12 and the results of Comparative Examples 1 to 8, a post-treatment step of bringing diluted fluorine gas in a range of 0.05 to 5% by volume of fluorine and carbon black into contact with gaseous water is performed. By performing the XPS analysis, the ratio of fluorine atoms to carbon atoms, that is, the F / C ratio is 0.001 or more and less than 0.025, and the ratio of oxygen atoms to carbon atoms, that is, the O / C ratio. It can be seen that post-treatment carbon black can be obtained, wherein the carbon black is 0.1 or more and less than 0.2. In addition, the non-aqueous electrolyte secondary battery manufactured using the treated carbon black in these ranges is compared with carbon black whose fluorine concentration is outside the above range or which has been treated with diluted fluorine containing oxygen gas. It can be seen that the internal resistance value is reduced and a high discharge capacity retention rate is maintained. XPS analysis revealed that at least one functional group of a C—OF group, a C—OH group, or a COOH group was present on the surface of the treated carbon black in Examples 1 to 12.
一方、比較例２の結果より、フッ素濃度０．００５体積％では、表面改質がほとんど進行しておらず、Ｆ／Ｃ比およびＯ／Ｃ値にもほとんど変化が見られず、内部抵抗値およびサイクル特性にも変化が見られなかった。また、比較例３の結果より、フッ素濃度７体積％では、Ｆ／Ｃ比およびＯ／Ｃ値が大きく上昇していたものの、内部抵抗値が増大し、サイクル特性が低下した。これは、フッ素濃度が高すぎ、カーボンブラックの表面の荒れが著しく、電荷の輸送を阻害したためと考えられる。 On the other hand, from the result of Comparative Example 2, when the fluorine concentration was 0.005 vol%, the surface modification hardly progressed, and the F / C ratio and the O / C value hardly changed, and the internal resistance value was There was no change in the cycle characteristics. From the results of Comparative Example 3, when the fluorine concentration was 7% by volume, the F / C ratio and the O / C value increased greatly, but the internal resistance value increased and the cycle characteristics deteriorated. This is presumably because the fluorine concentration was too high, the surface of the carbon black was extremely rough, and charge transport was inhibited.
比較例４では、フッ素と酸素を窒素で希釈したガスでカーボンブラックを処理したため、処理後カーボンブラックのＯ／Ｃ値が高くなり、内部抵抗値が増大し、サイクル特性が低下した。これは、フッ素と酸素によるフッ素処理により、カーボンブラックの架橋構造が変化し、炭素−炭素間の導電パスが阻害されたため、内部抵抗値が増大したものと思われる。 In Comparative Example 4, since carbon black was treated with a gas obtained by diluting fluorine and oxygen with nitrogen, the O / C value of the treated carbon black increased, the internal resistance value increased, and the cycle characteristics deteriorated. This is presumably because the cross-linking structure of carbon black was changed by the fluorine treatment with fluorine and oxygen, and the conductive path between carbon and carbon was inhibited, so that the internal resistance value was increased.
比較例５では、処理温度が８０℃であるため、フッ素処理が強力に進行し、処理後カーボンブラックのＦ／Ｃ比が大きく上昇した。フッ素処理の際に、カーボンブラックの表面に荒れが生じたと考えられ、内部抵抗値が増大し、サイクル特性が低下した。 In Comparative Example 5, since the treatment temperature was 80 ° C., the fluorine treatment proceeded strongly, and the F / C ratio of the treated carbon black was greatly increased. It was considered that the surface of the carbon black was roughened during the fluorine treatment, the internal resistance value increased, and the cycle characteristics deteriorated.
比較例６では、フッ素処理後の後処理工程にて、酸素ガスにて暴露したが、比較例7と同等の高いＦ／Ｃ比を持ち、さらに、ＣＦ基がＣＯＦ基などに変わったり、不安定な結合状態であった末端置換基が酸化されたりしたと見られるＯ／Ｃ比の上昇が見られた。比較例６では、内部抵抗値が高く、サイクル特性は低下した。 In Comparative Example 6, it was exposed to oxygen gas in the post-treatment process after the fluorine treatment, but it has a high F / C ratio equivalent to that of Comparative Example 7, and the CF group is changed to a COF group or the like. An increase in the O / C ratio, which seems to be that the terminal substituents that were in a stable bound state were oxidized, was observed. In Comparative Example 6, the internal resistance value was high, and the cycle characteristics deteriorated.
比較例７では、カーボンブラックをフッ素処理後に不活性ガスにて後処理工程を行ったため、処理後カーボンブラックにフッ素成分が多量に残った上に、処理前カーボンブラックと比較してＯ／Ｃ比がほとんど増えていないことから、ＣＯＨ基やＣＯＯＨ基の生成もなかったと考えられ、内部抵抗値が高く、サイクル特性も低かった。 In Comparative Example 7, since the carbon black was subjected to a post-treatment step with an inert gas after the fluorine treatment, a large amount of fluorine components remained in the carbon black after the treatment, and the O / C ratio compared with the carbon black before the treatment. Therefore, it was considered that no COH group or COOH group was generated, and the internal resistance value was high and the cycle characteristics were low.
Claims (12)
ＢＥＴ比表面積が２０ｍ２／ｇ以上であって１００ｍ２／ｇ未満であり、
ＸＰＳ分析により測定した、フッ素原子の炭素原子に対する割合であるＦ／Ｃ比が０．００２以上であって０．０２５未満であり、かつ、酸素原子の炭素原子に対する割合であるＯ／Ｃ比が０．０１以上であって０．１未満であるカーボンブラック。 Carbon black used as a conductive aid for electrodes of nonaqueous electrolyte secondary batteries,
BET specific surface area is 20 m 2 / g or more and less than 100 m 2 / g,
The F / C ratio, which is the ratio of fluorine atoms to carbon atoms, measured by XPS analysis is 0.002 or more and less than 0.025, and the O / C ratio, which is the ratio of oxygen atoms to carbon atoms, is Carbon black that is 0.01 or more and less than 0.1.
前記集電体上に形成され、請求項１〜３に記載のカーボンブラックと、電極活物質とを含む電極層と、
からなる非水電解質二次電池用電極。 A current collector made of metal foil;
An electrode layer formed on the current collector and comprising the carbon black according to claim 1 and an electrode active material,
An electrode for a non-aqueous electrolyte secondary battery.
前記正極及び前記負極の何れか又は両方が請求項４に記載の非水電解質二次電池用電極である非水電解質二次電池。 Having a positive electrode, a negative electrode, and an electrolyte;
The nonaqueous electrolyte secondary battery in which any one or both of the said positive electrode and the said negative electrode are the electrodes for nonaqueous electrolyte secondary batteries of Claim 4.
フッ素処理後のカーボンブラックを気体の水と接触させる後処理工程と、
を含む、請求項１又は２記載のカーボンブラックの製造方法。 Carbon black having a BET specific surface area of 95 m 2 / g or less be at at 25m 2 / g or more and at 50 ° C. from 10 ° C., and the fluorine treatment step of contacting a process gas consisting of fluorine gas and inert gas, wherein, The concentration of fluorine gas in the processing gas is 0.01 to 5% by volume;
A post-treatment step of contacting the carbon black after fluorine treatment with gaseous water;
The manufacturing method of the carbon black of Claim 1 or 2 containing this.
前記ペーストを集電体に塗布し、乾燥する工程と、
を含む非水電解質二次電池用電極の製造方法。 A step of creating a paste by dispersing the carbon black according to claim 1 or 2 and an electrode active material in a dispersion medium;
Applying the paste to a current collector and drying;
The manufacturing method of the electrode for nonaqueous electrolyte secondary batteries containing.
The method for producing an electrode for a non-aqueous electrolyte secondary battery according to claim 11, further comprising a binder and a viscosity modifier in the paste.
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