JP2010205870A - Electrolyte additive for electric double-layer capacitor, electrolyte, and electric double-layer capacitor - Google Patents

Electrolyte additive for electric double-layer capacitor, electrolyte, and electric double-layer capacitor Download PDF

Info

Publication number
JP2010205870A
JP2010205870A JP2009048883A JP2009048883A JP2010205870A JP 2010205870 A JP2010205870 A JP 2010205870A JP 2009048883 A JP2009048883 A JP 2009048883A JP 2009048883 A JP2009048883 A JP 2009048883A JP 2010205870 A JP2010205870 A JP 2010205870A
Authority
JP
Japan
Prior art keywords
electric double
layer capacitor
electrolyte
additive
double layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2009048883A
Other languages
Japanese (ja)
Inventor
Soji Shiraishi
壮志 白石
Natsuki Ozawa
夏樹 小澤
Kaoru Sunaga
薫 須永
Takashi Tonouchi
敬 登之内
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Meidensha Corp
Gunma University NUC
Meidensha Electric Manufacturing Co Ltd
Original Assignee
Meidensha Corp
Gunma University NUC
Meidensha Electric Manufacturing Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Meidensha Corp, Gunma University NUC, Meidensha Electric Manufacturing Co Ltd filed Critical Meidensha Corp
Priority to JP2009048883A priority Critical patent/JP2010205870A/en
Publication of JP2010205870A publication Critical patent/JP2010205870A/en
Pending legal-status Critical Current

Links

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/13—Energy storage using capacitors

Landscapes

  • Electric Double-Layer Capacitors Or The Like (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte additive with which a high-performance electric double-layer capacitor having excellent durability to high-voltage charging at higher temperature as compared with the conventional art can be obtained, and to provide an electrolyte and the electric double-layer capacitor. <P>SOLUTION: For the electric double-layer capacitor having a polarizable electrode immersed in an electrolyte, an electrolyte which contains an electrolytically polymerizable polymerprecursor by a 0.005 to 0.05M concentration as an additive is used, and initial charging is performed to electrolytically polymerize the electrolytically polymerizable polymerprecursor contained in the electrolyte; and a polymer produced by the electrolytic polymerization is deposited on an electrochemically active point present on a positive electrode-side polarizable electrode surface to coat the electrochemically active point with the polymer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、高温下での高電圧充電に対し優れた耐久性を有するキャパシタを実現し得る電気二重層キャパシタ用電解液添加剤、電解液及び電気二重層キャパシタに関するものである。   The present invention relates to an electrolytic solution additive for an electric double layer capacitor, an electrolytic solution, and an electric double layer capacitor capable of realizing a capacitor having excellent durability against high voltage charging at a high temperature.

電気二重層キャパシタ（Electric Double Layer Capacitor）は、活性炭などの多孔質炭素電極内の細孔に形成されるイオンの吸着層、即ち電気二重層に電荷を蓄える蓄電器（コンデンサ）である。   An electric double layer capacitor (electric double layer capacitor) is a capacitor (capacitor) that stores an electric charge in an adsorption layer of ions formed in pores in a porous carbon electrode such as activated carbon, that is, an electric double layer.

図６に示すように、電気二重層キャパシタ１０は、電解液１１に浸漬した二枚の活性炭電極１２，１３間に電源１４を繋いで電圧を印加することで充電される。充電時は電解質イオンが電極表面に吸着する。具体的には、正極１２では正孔（ｈ+）に電解液１１中の陰イオン（−）が、負極１３では電子（ｅ-）に電解液１１中の陽イオン（＋）がそれぞれ引きつけられ、正孔（ｈ+）と陰イオン（−）とは、また電子（ｅ-）と陽イオン（＋）とはおよそ数Åという極小の距離をおいて配向し電気二重層を形成する。この状態は電源が外されても維持され、化学反応を利用することなく蓄電状態を維持する。放電時には吸着していた陽イオン並びに陰イオンがそれぞれの電極から脱離する。具体的には、電子（ｅ-）が正極１２に戻り、それにつれて正孔（ｈ+）がなくなっていき、これに伴い、陽イオン、陰イオンが電解液中に再び拡散する。このように、充放電の全過程にわたって、キャパシタ材料には何の変化も伴わないため、化学反応による発熱や劣化がなく、長寿命を保つことができる。 As shown in FIG. 6, the electric double layer capacitor 10 is charged by connecting a power source 14 between two activated carbon electrodes 12 and 13 immersed in an electrolytic solution 11 and applying a voltage. During charging, electrolyte ions are adsorbed on the electrode surface. Specifically, the positive electrode 12 attracts positive ions ( − ) in the electrolytic solution 11 to holes (h + ), and the negative electrode 13 attracts positive ions (+) in the electrolytic solution 11 to electrons (e − ). The holes (h + ) and the anions (−) and the electrons (e − ) and the cations (+) are aligned with a minimum distance of about several tens to form an electric double layer. This state is maintained even when the power supply is removed, and the charged state is maintained without using a chemical reaction. The cations and anions adsorbed at the time of discharge are desorbed from the respective electrodes. Specifically, the electrons (e − ) return to the positive electrode 12, and as a result, holes (h + ) disappear. Along with this, cations and anions diffuse again into the electrolytic solution. As described above, since no change is caused in the capacitor material throughout the entire charging and discharging process, there is no heat generation or deterioration due to a chemical reaction, and a long life can be maintained.

このような電気二重層キャパシタでは、電解液としてテトラエチルアンモニウムテトラフルオロホウ酸を電解質塩とするプロピレンカーボネート溶液などが使用されている（例えば、特許文献１参照。）。   In such an electric double layer capacitor, a propylene carbonate solution containing tetraethylammonium tetrafluoroboric acid as an electrolyte salt is used as an electrolytic solution (see, for example, Patent Document 1).

電気二重層キャパシタは、一般的に二次電池に比べて(1)高速での充放電が可能、(2)充放電サイクルの可逆性が高い、(3)サイクル寿命が長い、(4)電極や電解質に重金属を用いていないので環境に優しい、といった特徴を有する。これらの特徴は、電気二重層キャパシタが重金属を用いておらず、またイオンの物理的吸脱離によって作動し、化学種の電子移動反応を伴わないことに由来する。電気二重層キャパシタはこのような特徴を生かして既にメモリーバックアップ用電源などとして実用化されている。最近では、鉄道車両に搭載した電力貯蔵システムやハイブリッド車の補助電源などの新たな用途の開拓を目指した研究開発が進んでおり、注目されている。   Electric double layer capacitors generally have (1) high-speed charge / discharge, (2) high reversibility of charge / discharge cycles, (3) long cycle life, and (4) electrodes compared to secondary batteries. And because it does not use heavy metals in the electrolyte, it is environmentally friendly. These characteristics are derived from the fact that the electric double layer capacitor does not use heavy metal, operates by physical adsorption / desorption of ions, and does not involve an electron transfer reaction of chemical species. Electric double layer capacitors have already been put to practical use as a memory backup power source by taking advantage of such characteristics. Recently, research and development aimed at pioneering new applications such as power storage systems mounted on railway vehicles and auxiliary power sources for hybrid vehicles has been attracting attention.

特開２００８−１４１１１６号公報（段落［００２９］、［００３５］）JP 2008-141116 A (paragraphs [0029] and [0035])

しかしながら、現状での電気二重層キャパシタは二次電池等に比べてエネルギー密度が低い問題点があり、また、過酷な環境下での充放電サイクルにおける信頼性が低いといった問題もあった。従って、上記新たな用途を開拓するためには、電気二重層キャパシタのエネルギー密度の改善と信頼性の向上が必要であり、電極材の高容量化並びに過酷環境下での容量安定性が求められている。   However, the current electric double layer capacitor has a problem that the energy density is lower than that of a secondary battery or the like, and also has a problem that reliability in a charge / discharge cycle under a harsh environment is low. Therefore, in order to pioneer the above-mentioned new applications, it is necessary to improve the energy density and reliability of the electric double layer capacitor, and it is required to increase the capacity of the electrode material and to have the capacity stability under severe environments. ing.

電気二重層キャパシタのエネルギー密度並びに信頼性を向上させるためには、高温下での高電圧充電による耐久試験後でも容量が低下しなければよい。そのためには、電解液や炭素自身の電気化学的な分解反応を抑制しなければならない。その手段の一つとして、活性炭などからなる分極性電極表面の修飾が挙げられる。そこで本発明では、電解液添加剤によって、分極性電極表面を適切に修飾し、高温下での高電圧充電に対する耐久性向上を目的とした。   In order to improve the energy density and reliability of the electric double layer capacitor, it is sufficient that the capacity does not decrease even after an endurance test by high voltage charging at a high temperature. For this purpose, the electrochemical decomposition reaction of the electrolyte and carbon itself must be suppressed. One of the means is modification of the surface of a polarizable electrode made of activated carbon or the like. Therefore, the present invention aims to improve the durability against high-voltage charging at high temperatures by appropriately modifying the polarizable electrode surface with an electrolytic solution additive.

本発明の目的は、従来よりも高温下での高電圧充電に対し優れた耐久性を有する高性能の電気二重層キャパシタを実現し得る、電気二重層キャパシタ用電解液添加剤、電解液及び電気二重層キャパシタを提供することにある。   An object of the present invention is to provide an electrolytic solution additive, an electrolytic solution, and an electrical solution for an electric double layer capacitor, which can realize a high performance electric double layer capacitor having excellent durability against high voltage charging at a higher temperature than before. It is to provide a double layer capacitor.

本発明の第１の観点は、電解重合性高分子前駆体からなることを特徴とする電気二重層キャパシタ用電解液添加剤である。   A first aspect of the present invention is an electrolytic solution additive for an electric double layer capacitor, comprising an electrolytic polymerizable polymer precursor.

本発明の第２の観点は、添加剤として電解重合性高分子前駆体を０．００５〜０．０５Ｍ濃度含有することを特徴とする電気二重層キャパシタ用電解液である。   According to a second aspect of the present invention, there is provided an electrolytic solution for an electric double layer capacitor containing an electropolymerizable polymer precursor at a concentration of 0.005 to 0.05 M as an additive.

本発明の第３の観点は、電解液中に分極性電極が浸されてなる電気二重層キャパシタにおいて、添加剤として電解重合性高分子前駆体を０．００５〜０．０５Ｍ濃度含有する電解液を用い、初期充電を行うことにより、電解液に含有する電解重合性高分子前駆体を電解重合させ、正極側分極性電極表面に存在する電気化学的活性点上に電解重合により生じた高分子を析出させ、電気化学的活性点を高分子により被覆したことを特徴とする。   According to a third aspect of the present invention, in an electric double layer capacitor in which a polarizable electrode is immersed in an electrolytic solution, the electrolytic solution contains an electrolytic polymerizable polymer precursor as an additive in a concentration of 0.005 to 0.05 M. The polymer produced by the electropolymerization on the electrochemically active sites present on the surface of the positive polarizable electrode is obtained by electropolymerizing the electropolymerizable polymer precursor contained in the electrolytic solution by performing initial charging. And the electrochemically active sites are covered with a polymer.

本発明の電気二重層キャパシタは、添加剤として電解重合性高分子前駆体を特定の割合で含有させた電解液を用いているので、この電気二重層キャパシタに対して初期充電を行うと、電解液に含有する電解重合性高分子前駆体が電解重合され、正極側分極性電極表面に存在する電気化学的活性点上に電解重合により生じた高分子が析出し、電気化学的活性点が高分子により被覆される。電極の劣化を引き起こすとされる電気化学的活性点が高分子により被覆されることで失活するため、この電気化学的活性点を起因とする電極の劣化が抑制される。結果として、本発明の電気二重層キャパシタは、従来よりも高温下での高電圧充電に対し優れた耐久性が得られる。   Since the electric double layer capacitor of the present invention uses an electrolytic solution containing an electropolymerizable polymer precursor in a specific ratio as an additive, when this electric double layer capacitor is initially charged, The electropolymerizable polymer precursor contained in the liquid is electropolymerized, and the polymer produced by the electropolymerization is deposited on the electrochemically active sites existing on the surface of the positive electrode side polarizable electrode, resulting in a high electrochemically active site. Covered by molecules. Since the electrochemically active sites that are supposed to cause deterioration of the electrodes are deactivated by being coated with the polymer, the deterioration of the electrodes caused by the electrochemically active points is suppressed. As a result, the electric double layer capacitor of the present invention has excellent durability against high voltage charging at a higher temperature than before.

実施例で使用した二極式セルの構造を示す図。The figure which shows the structure of the bipolar cell used in the Example. 電気二重層キャパシタの充放電時の電圧変化と正極及び負極の電極電位変化を示す図。The figure which shows the voltage change at the time of charging / discharging of an electrical double layer capacitor, and the electrode potential change of a positive electrode and a negative electrode. 電解重合性高分子前駆体含有電解液を用いたキャパシタを初期充電したときの正極側分極性電極表面に生じる効果を示す概念図。The conceptual diagram which shows the effect produced on the positive electrode side polarizable electrode surface when the capacitor using the electropolymerizable polymer precursor containing electrolyte solution is initially charged. 耐久試験後の分極性電極及びポリピロールのラマンスペクトルを示す図。The figure which shows the Raman spectrum of the polarizable electrode and polypyrrole after an endurance test. 耐久試験後の分極性電極表面の走査型電子顕微鏡写真を示す図。The figure which shows the scanning electron micrograph of the polarizable electrode surface after an endurance test. 一般的な電気二重層キャパシタの充放電を示す原理図。The principle figure which shows charging / discharging of a general electric double layer capacitor.

次に本発明を実施するための形態を説明する。   Next, the form for implementing this invention is demonstrated.

本発明の電気二重層キャパシタ用電解液添加剤は、電解重合性高分子前駆体からなることを特徴とする。電解重合性高分子前駆体からなる本発明の電解液添加剤を用いることで、この添加剤を含有させた電解液を用いた電気二重層キャパシタに対して初期充電を行うと、電解液に含有する電解重合性高分子前駆体が電解重合され、正極側分極性電極表面に存在する電気化学的活性点上に電解重合により生じた高分子が析出し、電気化学的活性点が高分子により被覆される。電極の劣化を引き起こすとされる電気化学的活性点が高分子により被覆されることで失活するため、この電気化学的活性点を起因とする電極の劣化が抑制される。結果として、電気二重層キャパシタの電解液に本発明の添加剤を含有させると、従来よりも高温下での高電圧充電に対し優れた耐久性が得られる。   The electrolytic solution additive for electric double layer capacitors of the present invention is characterized by comprising an electrolytic polymerizable polymer precursor. By using the electrolytic solution additive of the present invention consisting of an electropolymerizable polymer precursor, when the initial charge is performed on the electric double layer capacitor using the electrolytic solution containing this additive, it is contained in the electrolytic solution. The electropolymerizable polymer precursor is electropolymerized, the polymer produced by electrolytic polymerization is deposited on the electrochemically active sites present on the surface of the positive electrode side polarizable electrode, and the electrochemically active sites are covered with the polymer. Is done. Since the electrochemically active sites that are supposed to cause deterioration of the electrodes are deactivated by being coated with the polymer, the deterioration of the electrodes caused by the electrochemically active points is suppressed. As a result, when the additive of the present invention is contained in the electrolytic solution of the electric double layer capacitor, durability superior to high voltage charging at a higher temperature than before can be obtained.

電解重合性高分子前駆体の具体例としては、ピロール、アニリン、インドール等が挙げられる。   Specific examples of the electropolymerizable polymer precursor include pyrrole, aniline, indole and the like.

また、本発明の電気二重層キャパシタ用電解液は、添加剤として電解重合性高分子前駆体を０．００５〜０．０５Ｍ濃度含有することを特徴とする。添加剤として電解重合性高分子前駆体を特定の割合で含有させた本発明の電解液を用いることで、この電解液を用いた電気二重層キャパシタに対して初期充電を行うと、電解液に含有する電解重合性高分子前駆体が電解重合され、正極側分極性電極表面に存在する電気化学的活性点上に電解重合により生じた高分子が析出し、電気化学的活性点が高分子により被覆される。電極の劣化を引き起こすとされる電気化学的活性点が高分子により被覆されることで失活するため、この電気化学的活性点を起因とする電極の劣化が抑制される。結果として、電気二重層キャパシタに本発明の電解液を用いると、従来よりも高温下での高電圧充電に対し優れた耐久性が得られる。   Moreover, the electrolytic solution for an electric double layer capacitor of the present invention is characterized by containing an electropolymerizable polymer precursor in a concentration of 0.005 to 0.05 M as an additive. By using the electrolytic solution of the present invention containing an electrolytic polymerizable polymer precursor in a specific ratio as an additive, when an initial charge is performed on an electric double layer capacitor using this electrolytic solution, the electrolytic solution The contained electropolymerizable polymer precursor is electrolytically polymerized, and the polymer produced by the electropolymerization is deposited on the electrochemically active sites present on the surface of the positive electrode side polarizable electrode. Covered. Since the electrochemically active sites that are supposed to cause deterioration of the electrodes are deactivated by being coated with the polymer, the deterioration of the electrodes caused by the electrochemically active points is suppressed. As a result, when the electrolytic solution of the present invention is used for an electric double layer capacitor, durability superior to high voltage charging at a higher temperature than before can be obtained.

電解液に含有させる前駆体の濃度を上記範囲内に規定したのは、前駆体の含有濃度が０．００５Ｍ濃度未満であると、電解重合により生じる析出高分子量が不足し、正極側分極性電極上の電気化学的活性点が十分に被覆されず、失活しない電気化学的活性点が数多く存在してしまうため、電気化学的活性点による電極の劣化を抑制する効果に乏しく、前駆体の含有濃度が０．０５Ｍ濃度を越えると電解重合により生じる析出高分子量が多すぎてしまい、正極側分極性電極上の電気化学的活性点の被覆だけにとどまらず、正極側分極性電極が有する細孔をも閉塞してしまう不具合を生じるためである。このうち、好ましくは０．０１〜０．０３Ｍ濃度である。   The concentration of the precursor to be contained in the electrolytic solution is defined within the above range because if the precursor concentration is less than 0.005M, the amount of precipitated polymer generated by electrolytic polymerization is insufficient, and the positive electrode side polarizable electrode The above electrochemically active sites are not sufficiently coated, and there are many electrochemically active sites that do not deactivate. When the concentration exceeds 0.05M, the amount of precipitated polymer produced by the electropolymerization is too large, and the pores of the positive polarizable electrode are not limited to the coating of the electrochemically active sites on the positive polarizable electrode. This is to cause a problem of blocking. Among these, Preferably it is a 0.01-0.03M density | concentration.

本発明の電気二重層キャパシタは、電解液中に分極性電極が浸されてなる電気二重層キャパシタの改良であり、添加剤として電解重合性高分子前駆体を０．００５〜０．０５Ｍ濃度含有する電解液を用い、初期充電を行うことにより、電解液に含有する電解重合性高分子前駆体を電解重合させ、正極側分極性電極表面に存在する電気化学的活性点上に電解重合により生じた高分子を析出させ、電気化学的活性点を高分子により被覆したことを特徴とする。   The electric double layer capacitor of the present invention is an improvement of the electric double layer capacitor in which a polarizable electrode is immersed in an electrolytic solution, and contains 0.005-0.05M concentration of an electropolymerizable polymer precursor as an additive. It is generated by electrolytic polymerization on the electrochemically active sites present on the surface of the positive polarizable electrode by electropolymerizing the electrolytic polymerizable polymer precursor contained in the electrolytic solution by performing initial charging using the electrolytic solution The polymer is deposited, and the electrochemically active sites are covered with the polymer.

添加剤として電解重合性高分子前駆体を特定の割合で含有させた電解液を用いた本発明の電気二重層キャパシタに対して初期充電を行うと、電解液に含有する電解重合性高分子前駆体が電解重合され、正極側分極性電極表面に存在する電気化学的活性点上に電解重合により生じた高分子が析出し、電気化学的活性点が高分子により被覆される。電極の劣化を引き起こすとされる電気化学的活性点が高分子により被覆されることで失活するため、この電気化学的活性点を起因とする電極の劣化が抑制される。結果として、本発明の電気二重層キャパシタは、従来よりも高温下での高電圧充電に対し優れた耐久性が得られる。   When initial charging is performed on the electric double layer capacitor of the present invention using an electrolytic solution containing an electrolytic polymerizable polymer precursor in a specific ratio as an additive, the electrolytic polymerizable polymer precursor contained in the electrolytic solution The body is electrolytically polymerized, the polymer produced by the electrolytic polymerization is deposited on the electrochemically active sites present on the surface of the positive electrode side polarizable electrode, and the electrochemically active sites are coated with the polymer. Since the electrochemically active sites that are supposed to cause deterioration of the electrodes are deactivated by being coated with the polymer, the deterioration of the electrodes caused by the electrochemically active points is suppressed. As a result, the electric double layer capacitor of the present invention has excellent durability against high voltage charging at a higher temperature than before.

本発明の電気二重層キャパシタは、集電体と分極性電極とセパレータを、集電体−分極性電極−セパレータ−分極性電極−集電体の順に重ね、電解液を含浸した構造を有する。この構造を基本単位とし、単位電気二重層キャパシタを多数積層し、電気的に接続して積層体を形成し、その電気容量が高められ、実用に供される。分極性電極を形成するには炭素材料に導電性補助剤、バインダを所定の割合で添加し、混練した後に、任意の形状に成形することが好適である。導電補助剤としてはカーボンブラックが挙げられる。バインダとしてはＰＴＦＥ（ポリテトラフルオロエチレン）が挙げられる。本発明の電気二重層キャパシタでは、集電極、セパレータ等は従来より知られている既存の材料を適用することが可能である。   The electric double layer capacitor of the present invention has a structure in which a current collector, a polarizable electrode, and a separator are stacked in the order of current collector-polarizable electrode-separator-polarizable electrode-current collector and impregnated with an electrolytic solution. Using this structure as a basic unit, a large number of unit electric double layer capacitors are stacked and electrically connected to form a stacked body, and its electric capacity is increased, which is put to practical use. In order to form a polarizable electrode, it is preferable that a conductive auxiliary agent and a binder are added to a carbon material at a predetermined ratio and kneaded, and then formed into an arbitrary shape. Carbon black is mentioned as a conductive support agent. Examples of the binder include PTFE (polytetrafluoroethylene). In the electric double layer capacitor of the present invention, it is possible to apply existing materials known in the art to the collector electrode, the separator and the like.

次に本発明の実施例を比較例とともに詳しく説明する。
＜実施例１＞
電気二重層キャパシタの分極性電極には正極側及び負極側ともに、水蒸気賦活によって調製されたフェノール樹脂系活性炭（ＢＥＴ比表面積：約２０００ｍ2／ｇ）を用いた。フェノール樹脂系活性炭は電気二重層キャパシタの電極材料として一般的に使用されている。また、添加剤が加えられていない電解液には、１．０Ｍ濃度のトリエチルメチルアンモニウムテトラフルオロボレート（(Ｃ2Ｈ5)3ＣＨ3ＮＢＦ4）を電解質塩として含むプロピレンカーボネート溶液を用いた。この電解液は、電気二重層キャパシタの有機系電解液として一般的である。 Next, examples of the present invention will be described in detail together with comparative examples.
<Example 1>
For the polarizable electrode of the electric double layer capacitor, phenol resin-based activated carbon (BET specific surface area: about 2000 m 2 / g) prepared by steam activation was used on both the positive electrode side and the negative electrode side. Phenol resin activated carbon is generally used as an electrode material for electric double layer capacitors. In addition, a propylene carbonate solution containing 1.0 M concentration of triethylmethylammonium tetrafluoroborate ((C 2 H 5 ) 3 CH 3 NBF 4 ) as an electrolyte salt was used as the electrolytic solution to which no additive was added. This electrolytic solution is generally used as an organic electrolytic solution for an electric double layer capacitor.

そして、容量測定及び耐久試験には、図１に示す構造を有するアルミニウム製二極式セルを用いた。この二極式セルは、電気配線を有する正極側アルミニウム製ボディ上に、正極側集電体−正極側分極性電極−セパレータ−テフロン（登録商標）ガイド−負極側分極性電極−負極側集電体の順に重ね、電極間に電解液を含浸させている。そして、重ね合わせた負極側集電体上にスプリングを備えた電極押さえ、電気配線を有する負極側アルミニウム製ボディを載せ、正極側アルミニウム製ボディと負極側アルミニウム製ボディとで挟み込んだ構造を有する。   For the capacity measurement and the durability test, an aluminum bipolar cell having the structure shown in FIG. 1 was used. This bipolar cell has a positive electrode side current collector, a positive electrode side polarizable electrode, a separator, a Teflon (registered trademark) guide, a negative electrode side polarizable electrode, and a negative electrode side current collector on a positive electrode side aluminum body having electrical wiring. The layers are stacked in order of the body, and the electrolyte is impregnated between the electrodes. Then, an electrode retainer having a spring and a negative electrode-side aluminum body having electric wiring are placed on the superimposed negative electrode-side current collector, and sandwiched between the positive electrode-side aluminum body and the negative electrode-side aluminum body.

容量は室温において定電流法（電流密度：８０ｍＡ／ｇ；測定電圧範囲：０〜２Ｖ）により求めた。次に、容量測定後、７０℃においてセルに３Ｖの電圧を１００時間印加することにより耐久試験を行った。続いて、耐久試験後、再び室温に戻し、容量を定電流法（電流密度：８０ｍＡ／ｇ：測定電圧範囲：０〜２Ｖ）により求めた。そして耐久試験前後の容量の比を容量維持率とした。   The capacity was determined at room temperature by the constant current method (current density: 80 mA / g; measurement voltage range: 0 to 2 V). Next, after the capacity measurement, a durability test was performed by applying a voltage of 3 V to the cell at 70 ° C. for 100 hours. Subsequently, after the durability test, the temperature was returned to room temperature, and the capacity was determined by a constant current method (current density: 80 mA / g: measurement voltage range: 0 to 2 V). The capacity ratio before and after the durability test was defined as the capacity maintenance rate.

電解液に含有させる添加剤としては、ピロール、アニリン、ビチオフェンを検討した。これらの有機物は、電気化学的に酸化すること、即ち、電極電位を高電位に分極することで、電解重合し、高分子となることが知られている。即ち、ポリピロール、ポリアニリン、ポリビチオフェンとなることが知られている。   As additives to be contained in the electrolytic solution, pyrrole, aniline, and bithiophene were examined. It is known that these organic substances are electrochemically oxidized, that is, when the electrode potential is polarized to a high potential, and electropolymerize to become a polymer. That is, it is known to be polypyrrole, polyaniline, or polybithiophene.

電気二重層キャパシタでは、図２に示す通り、充電時に正極側分極性電極が高電位に分極される。従って、電解液中に上記添加剤が含まれていれば、これらの有機物からなる添加剤は充電中に正極側分極性電極上にて電解重合し、その結果、高分子が正極側分極性電極上に析出すると予想される。高分子が析出する場所は、正極側分極性電極上の電気化学的活性点である。この電気化学的活性点は、電解液や電極そのものが分解し易い部分でもあり、高温下の高電圧充電によってキャパシタを劣化させる要因とも考えられる。従って、図３に示すように、電解重合により生じた高分子によって電気化学的活性点が被覆されれば、電気化学的活性点が失活され、電気二重層キャパシタの耐久性が向上することが期待される。   In the electric double layer capacitor, as shown in FIG. 2, the positive polarizable electrode is polarized to a high potential during charging. Therefore, if the above-mentioned additive is contained in the electrolytic solution, these organic additives are electrolytically polymerized on the positive polarizable electrode during charging, and as a result, the polymer is converted into the positive polarizable electrode. It is expected to deposit on top. The place where the polymer precipitates is the electrochemically active point on the positive electrode side polarizable electrode. This electrochemically active site is also a part where the electrolytic solution or the electrode itself is easily decomposed, and is considered to be a factor of degrading the capacitor by high voltage charging at a high temperature. Therefore, as shown in FIG. 3, if the electrochemically active sites are covered with a polymer produced by electrolytic polymerization, the electrochemically active sites are deactivated, and the durability of the electric double layer capacitor is improved. Be expected.

＜比較試験及び評価＞
上記容量測定及び耐久試験の結果を次の表１に示す。 <Comparison test and evaluation>
The results of the capacity measurement and the durability test are shown in Table 1 below.

表１から明らかなように、添加剤としてピロールを含有させた電解液を用いることにより、初期容量及び容量維持率を改善できることが判った。但し、容量維持率については含有割合が０．０３Ｍ濃度のときに最も効果的であり、０．０６Ｍ濃度になると逆に容量維持率は低下した。このような結果から、容量維持率の向上に寄与し得る適切なピロールの含有濃度範囲が存在することが確認された。また、添加剤としてアニリンを０．０３Ｍ濃度含有させた電解液を用いた場合でも容量維持率を改善できる結果が確認された。一方、添加剤としてビチオフェンを０．０３Ｍ濃度含有させた電解液を用いた場合では、容量維持率が著しく低下する結果となった。 As is apparent from Table 1, it was found that the initial capacity and capacity retention rate can be improved by using an electrolytic solution containing pyrrole as an additive. However, the capacity retention rate was most effective when the content ratio was 0.03M concentration, and conversely, the capacity retention rate decreased when it reached 0.06M concentration. From these results, it was confirmed that there was an appropriate concentration range of pyrrole that could contribute to the improvement of the capacity retention rate. Further, it was confirmed that even when an electrolytic solution containing aniline at a concentration of 0.03 M was used as an additive, the capacity retention rate could be improved. On the other hand, when an electrolytic solution containing 0.03 M of bithiophene as an additive was used, the capacity retention rate was significantly reduced.

次に、耐久試験を行った後の分極性電極について、ラマン分光測定を行った。図４に、添加剤としてピロールを０．０６Ｍ濃度含有させた電解液を用いたときの正極側分極性電極及び負極側分極性電極、添加剤未使用の電解液を用いたときの正極側分極性電極のラマンスペクトルをそれぞれ示す。なお、図４では、比較のため市販のポリピロール粉末のラマンスペクトルも示した。   Next, the Raman spectroscopic measurement was performed on the polarizable electrode after the durability test was performed. FIG. 4 shows the positive electrode side polarizable electrode and negative electrode side polarizable electrode when using an electrolyte solution containing 0.06M pyrrole as an additive, and the positive electrode side component when using an additive-free electrolyte solution. The Raman spectrum of a polar electrode is shown, respectively. In FIG. 4, the Raman spectrum of a commercially available polypyrrole powder is also shown for comparison.

図４から明らかなように、添加剤未使用の電解液を用いたときの正極側分極性電極のラマンスペクトルには、活性炭に特有のＧバンド（１５９０ｃｍ-1付近）とＤバンド（１３３０ｃｍ-1付近）が観測された。一方、ピロールを０．０６Ｍ濃度含有させた電解液を用いたときの正極側分極性電極では、市販のポリピロール粉末のラマンスペクトルに類似したラマンスペクトルが得られた。このラマンスペクトルでは１６００ｃｍ-1のバンドはＣ＝Ｃ伸縮振動、１３５０ｃｍ-1付近のブロードなバンドは、Ｃ−Ｎ伸縮振動に帰属される。これは、充電時に正極側分極性電極上でピロールの電解重合が生じ、ポリピロールが析出したことを示している。また、添加剤としてピロールを０．０６Ｍ濃度含有させた電解液を用いたときでも、負極側分極性電極のラマンスペクトルは、添加剤未使用の電解液を用いたときの正極側分極性電極のラマンスペクトルとほぼ同じであったことから、負極側分極性電極上にはポリピロールが析出しないことが確認された。 As apparent from FIG. 4, the Raman spectra of the positive electrode side polarizable electrodes when using the additive unused electrolyte, activated carbon specific G band (1590 cm -1 vicinity) and D-band (1330 cm -1 Nearby) was observed. On the other hand, a Raman spectrum similar to the Raman spectrum of the commercially available polypyrrole powder was obtained with the positive electrode side polarizable electrode when an electrolyte containing 0.06 M of pyrrole was used. The band of 1600 cm -1 in the Raman spectrum C = C stretching vibration, the broad band near 1350 cm -1, attributed to C-N stretching vibration. This indicates that polypyrrole was deposited by electrolytic polymerization of pyrrole on the positive electrode side polarizable electrode during charging. Even when an electrolyte containing 0.06M pyrrole as an additive is used, the Raman spectrum of the negative polarizable electrode shows that of the positive polarizable electrode when an additive-free electrolytic solution is used. Since it was almost the same as the Raman spectrum, it was confirmed that polypyrrole did not precipitate on the negative electrode side polarizable electrode.

次に、耐久試験を行った後の分極性電極について、走査電子顕微鏡（ＳＥＭ）による撮影を行った。図５（ａ）に、添加剤未使用の電解液を用いたときの正極側分極性電極のＳＥＭ像を、図５（ｂ）に、添加剤としてピロールを０．０６Ｍ濃度含有させた電解液を用いたときの正極側分極性電極のＳＥＭ像をそれぞれ示す。   Next, the polarizing electrode after the endurance test was taken with a scanning electron microscope (SEM). FIG. 5 (a) shows an SEM image of the positive electrode side polarizable electrode when an additive-free electrolyte is used, and FIG. 5 (b) shows an electrolyte containing 0.06M pyrrole as an additive. The SEM image of the positive electrode side polarizable electrode when using is shown, respectively.

図５（ａ）から明らかなように、添加剤未使用の電解液を用いたときの正極側分極性電極には、活性炭粒子と導電補助材のアセチレンブラック微粒子からなる典型的なキャパシタ用コンポジット電極の微細構造が確認された。一方、図５（ｂ）から明らかなように、添加剤としてピロールを含有させた電解液を用いたときの正極側分極性電極には、ポリピロールと思われる析出物が電極上に観察された。この結果は、前述したラマン測定の結果と一致している。   As is clear from FIG. 5 (a), the positive electrode-side polarizable electrode when the additive-free electrolyte is used is a typical composite electrode for capacitors made of activated carbon particles and acetylene black fine particles of a conductive auxiliary material. The microstructure was confirmed. On the other hand, as is clear from FIG. 5 (b), in the positive electrode side polarizable electrode when an electrolytic solution containing pyrrole as an additive was used, deposits that seemed to be polypyrrole were observed on the electrode. This result is consistent with the result of the Raman measurement described above.

以上の結果から、初期容量及び容量維持率の向上は、ポリピロールが正極側分極性電極上に電解重合により析出したためと結論づけることができる。   From the above results, it can be concluded that the improvement of the initial capacity and capacity retention rate is due to the polypyrrole deposited on the positive electrode side polarizable electrode by electrolytic polymerization.

ポリピロールは、キャパシタ用電解液中で電気化学的酸化還元反応するため、その容量が擬似的にキャパシタ容量に寄与することが知られている（擬似容量）。そのために、初期容量が向上したと思われる。   Since polypyrrole undergoes an electrochemical oxidation-reduction reaction in the electrolytic solution for capacitors, it is known that its capacity contributes to the capacitor capacity in a pseudo manner (pseudo capacity). Therefore, the initial capacity seems to have improved.

一方、高温下での高電圧印加に対する容量維持率（耐久性）が改善したのは、電極の劣化を引き起こす電気化学的活性点をポリピロール析出物が被覆し、電気化学的活性点を失活させたことによると推察される。   On the other hand, the capacity retention ratio (durability) against high voltage application at high temperature was improved because the polypyrrole precipitates covered the electrochemically active sites that cause electrode deterioration, and the electrochemically active sites were deactivated. It is presumed that.

また、添加剤としてピロールを０．０６Ｍ濃度含有させた電解液を用いた正極側分極性電極について、耐久試験後の正極側分極性電極の細孔構造を分析したところ、著しく比表面積が低下していた。これは、電解液へのピロールの含有濃度が高すぎると、電解重合により析出したポリピロールが正極側分極性電極表面に存在する電気化学的活性点だけの被覆にとどまらず、正極側分極性電極の細孔をも閉塞してしまうためであると考えられる。   Moreover, the positive electrode polarizable electrode using an electrolyte containing 0.06M pyrrole as an additive was analyzed for the pore structure of the positive electrode polarizable electrode after the durability test. It was. This is because if the content of pyrrole in the electrolyte solution is too high, the polypyrrole deposited by electrolytic polymerization is not limited to the coating of only the electrochemically active sites present on the surface of the positive electrode side polarizable electrode. This is probably because the pores are also blocked.

添加剤としてアニリンを使用した場合についてもピロールを使用した場合と同様の理由で容量維持率の改善に効果があると思われる。   The case where aniline is used as an additive is also considered to be effective in improving the capacity retention rate for the same reason as when pyrrole is used.

ただし、ビチオフェンにはその効果がないことから、キャパシタの耐久性向上のためには適切な高分子前駆体を選択する必要がある。   However, since bithiophene has no effect, it is necessary to select an appropriate polymer precursor in order to improve the durability of the capacitor.

１０ 電気二重層キャパシタ
１１ 電解液
１２ 正極
１３ 負極
１４ 電源 10 Electric Double Layer Capacitor 11 Electrolyte 12 Positive Electrode 13 Negative Electrode 14 Power Supply

Claims (3)

電解重合性高分子前駆体からなることを特徴とする電気二重層キャパシタ用電解液添加剤。   An electrolytic solution additive for an electric double layer capacitor, comprising an electrolytic polymerizable polymer precursor. 添加剤として電解重合性高分子前駆体を０．００５〜０．０５Ｍ濃度含有することを特徴とする電気二重層キャパシタ用電解液。   An electrolytic solution for an electric double layer capacitor comprising an electrolytic polymerizable polymer precursor in a concentration of 0.005 to 0.05 M as an additive. 電解液中に分極性電極が浸されてなる電気二重層キャパシタにおいて、
添加剤として電解重合性高分子前駆体を０．００５〜０．０５Ｍ濃度含有する電解液を用い、
初期充電を行うことにより、前記電解液に含有する電解重合性高分子前駆体を電解重合させ、正極側分極性電極表面に存在する電気化学的活性点上に前記電解重合により生じた高分子を析出させ、前記電気化学的活性点を高分子により被覆した
ことを特徴とする電気二重層キャパシタ。 In an electric double layer capacitor in which a polarizable electrode is immersed in an electrolyte,
Using an electrolytic solution containing 0.005-0.05M concentration of an electropolymerizable polymer precursor as an additive,
By performing initial charging, the electropolymerizable polymer precursor contained in the electrolytic solution is electropolymerized, and the polymer generated by the electropolymerization is formed on the electrochemically active sites present on the surface of the positive polarizable electrode. An electric double layer capacitor, wherein the electrochemically active sites are deposited and coated with a polymer.
JP2009048883A 2009-03-03 2009-03-03 Electrolyte additive for electric double-layer capacitor, electrolyte, and electric double-layer capacitor Pending JP2010205870A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2009048883A JP2010205870A (en) 2009-03-03 2009-03-03 Electrolyte additive for electric double-layer capacitor, electrolyte, and electric double-layer capacitor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2009048883A JP2010205870A (en) 2009-03-03 2009-03-03 Electrolyte additive for electric double-layer capacitor, electrolyte, and electric double-layer capacitor

Publications (1)

Publication Number Publication Date
JP2010205870A true JP2010205870A (en) 2010-09-16

Family

ID=42967097

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2009048883A Pending JP2010205870A (en) 2009-03-03 2009-03-03 Electrolyte additive for electric double-layer capacitor, electrolyte, and electric double-layer capacitor

Country Status (1)

Country Link
JP (1) JP2010205870A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013174098A (en) * 2012-02-27 2013-09-05 Maezawa Ind Inc Emergency shutdown gate device
US9165720B2 (en) 2011-04-11 2015-10-20 The Yokohama Rubber Co., Ltd. Conductive polymer/porous carbon material composite and electrode material using same
US9368292B2 (en) 2012-11-13 2016-06-14 Kuraray Chemical Co., Ltd. Carbon material for polarizable electrodes and method for producing same
KR20180058717A (en) 2015-09-25 2018-06-01 닛신보 홀딩스 가부시키 가이샤 Additive for electrolyte

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007019469A (en) * 2005-06-10 2007-01-25 Matsushita Electric Ind Co Ltd Electrochemistry capacitor and manufacturing method
JP2008226606A (en) * 2007-03-12 2008-09-25 Denso Corp Manufacturing method of lithium secondary battery

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007019469A (en) * 2005-06-10 2007-01-25 Matsushita Electric Ind Co Ltd Electrochemistry capacitor and manufacturing method
JP2008226606A (en) * 2007-03-12 2008-09-25 Denso Corp Manufacturing method of lithium secondary battery

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9165720B2 (en) 2011-04-11 2015-10-20 The Yokohama Rubber Co., Ltd. Conductive polymer/porous carbon material composite and electrode material using same
JP2013174098A (en) * 2012-02-27 2013-09-05 Maezawa Ind Inc Emergency shutdown gate device
US9368292B2 (en) 2012-11-13 2016-06-14 Kuraray Chemical Co., Ltd. Carbon material for polarizable electrodes and method for producing same
KR20180058717A (en) 2015-09-25 2018-06-01 닛신보 홀딩스 가부시키 가이샤 Additive for electrolyte
US10658700B2 (en) 2015-09-25 2020-05-19 Nisshinbo Holdings Inc. Additive for electrolyte solutions

Similar Documents

Publication Publication Date Title
Wu et al. An aqueous Zn‐ion hybrid supercapacitor with high energy density and ultrastability up to 80 000 cycles
JP5322435B2 (en) Negative electrode active material for electricity storage devices
JP4924966B2 (en) Lithium ion capacitor
Sun et al. Electrochemical performance of electrochemical capacitors using Cu (II)-containing ionic liquid as the electrolyte
Li et al. Improvement in the surface properties of activated carbon via steam pretreatment for high performance supercapacitors
JP5931326B2 (en) Activated carbon for electric double layer capacitors
Zeng et al. Nitrogen‐Doped Hierarchically Porous Carbon Materials with Enhanced Performance for Supercapacitor
JP2014530502A (en) High voltage electrochemical double layer capacitor
JP6417524B2 (en) High capacitance activated carbon and carbon-based electrode
KR20130017987A (en) Electrodes for electrochemical capacitor and electrochemical capacitor comprising the same
Kurzweil Electrochemical double-layer capacitors
Wang et al. Ultrafast high energy supercapacitors based on pillared graphene nanostructures
TW201526048A (en) Ultracapacitor with improved aging performance
JP2016538715A (en) Ultracapacitor with improved aging performance
Zhou et al. Three‐dimensional NiMoO4 nanosheets supported on a carbon fibers@ pre‐treated Ni Foam (CF@ PNF) substrate as advanced electrodes for asymmetric supercapacitors
JP2008182212A (en) Faraday capacitive type capacitor
JP6006624B2 (en) Activated carbon for power storage device doped with sulfur and method for producing the same
JP2010205870A (en) Electrolyte additive for electric double-layer capacitor, electrolyte, and electric double-layer capacitor
KR101861356B1 (en) Graphene-Conductive Polymer Composite for Supercapacitor electrodes and preparing method thereof
Inal et al. Waste tea derived activated carbon/polyaniline composites as supercapacitor electrodes
Kurig et al. Substituted phosphonium cation based electrolytes for nonaqueous electrical double-layer capacitors
JP2018092978A (en) Electric double layer capacitor
KR100745193B1 (en) Manufacturing method of cnf/daaq composite electrode for supercapacitor
JP2020088119A (en) Manufacturing method of carbon material for electrical double layer capacitor
JP4732074B2 (en) Lithium ion capacitor

Legal Events

Date Code Title Description
A621 Written request for application examination

Effective date: 20111221

Free format text: JAPANESE INTERMEDIATE CODE: A621

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A821

Effective date: 20111221

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20121210

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20121225

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20130212

A02 Decision of refusal

Free format text: JAPANESE INTERMEDIATE CODE: A02

Effective date: 20130423