JP3991437B2 - Electric double layer capacitor and manufacturing method thereof - Google Patents
Electric double layer capacitor and manufacturing method thereof Download PDFInfo
- Publication number
- JP3991437B2 JP3991437B2 JP09961398A JP9961398A JP3991437B2 JP 3991437 B2 JP3991437 B2 JP 3991437B2 JP 09961398 A JP09961398 A JP 09961398A JP 9961398 A JP9961398 A JP 9961398A JP 3991437 B2 JP3991437 B2 JP 3991437B2
- Authority
- JP
- Japan
- Prior art keywords
- double layer
- electric double
- electrode
- layer capacitor
- conductive
- 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.)
- Expired - Fee Related
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
Description
【０００１】
【発明の属する技術分野】
本発明は電気二重層コンデンサ、特に作動信頼性に優れた電気二重層コンデンサに関する。
【０００２】
【従来の技術】
電気二重層コンデンサは、電極と電解液との界面に形成される電気二重層に電荷を蓄積することを原理としており、電気二重層コンデンサの容量密度を向上させるため、電極には高比表面積の活性炭、カーボンブラック等の炭素材料、金属又は導電性金属酸化物の微粒子等が用いられる。充電及び放電を効率よく行うため、電極は集電体と呼ばれる金属や黒鉛等の電子伝導性の抵抗の小さい層や箔に接合されている。集電体には通常電気化学的に耐食性の高いアルミウム等のバルブ金属、ＳＵＳ３０４、ＳＵＳ３１６Ｌ等のステンレス鋼等が使用されている。
【０００３】
電気二重層コンデンサには、電解液として有機電解液を用いたものと水系電解液を用いたものがあるが、作動電圧が高く、充電状態のエネルギ密度を大きくできる点で有機電解液を用いた電気二重層コンデンサが注目されている。有機電解液を用いる場合、電気二重層コンデンサの内部に水分が存在すると、水分が電気分解して性能の劣化を招くため、電極は充分に脱水する必要があり、通常、減圧下で加熱する乾燥処理が施されている。
【０００４】
電極には主に活性炭が使用されるが、活性炭は通常粉末状であるため、例えばポリテトラフルオロエチレン（以下、ＰＴＦＥという）等の含フッ素樹脂を含むバインダと混合してシート状電極に成形し、集電体と電気的に接続させた電極体として用いることが知られている。このとき、電極と集電体を密着させ、かつ電気的な接触抵抗が小さくなるように、導電性接着層を介して接合したものも多くある。しかし、含フッ素樹脂は接着が難しい性質を有しており、接合強度を高くすることが難しい。
【０００５】
導電性接着層は電気化学的な耐食性を必要とされるので、電子伝導性を与えるフィラーとしてカーボンブラックや黒鉛等の非金属系材料が含まれることが好ましい。さらに接合強度を確保するため、導電性接着層には種々のバインダ成分が使用される。この目的に使用されるバインダ成分としては、セルロース、ポリビニルアルコール等の樹脂（特開昭５９−３９１５、特開昭６２−２００７１５）、水ガラス等の無機系バインダ成分（特開平２−８２６０８）や、ポリイミド系樹脂（特開平９−２７０３７０）が知られている。
【０００６】
しかし、セルロース、ポリビニルアルコール等の樹脂系バインダ成分を含む導電性接着剤を用いた場合、有機電解液に対する耐性が不充分なため、電極と集電体が剥離を起こしやすい。また、耐熱性が１２０℃前後であるため高温での乾燥処理ができず、活性炭に吸着している残存水分を充分には除去しがたく、その残存水分が電気分解して電気二重層コンデンサの性能が劣化する等の問題がある。
【０００７】
また、水ガラス等の無機系バインダでは、耐熱性は高いが電極と金属集電体との接着強度が不充分であり、アルカリ成分の溶出や残留水分によって電気二重層コンデンサの性能劣化が起きる問題がある。ポリイミド系樹脂は耐熱性、接着性の面では充分であるが、樹脂を溶解する溶剤としてＮ−メチル−２−ピロリドンのような極性の高い高沸点の溶剤を用いなければならないため、溶剤の除去の点で問題がある。
【０００８】
【発明が解決しようとする課題】
本発明は上記従来技術における問題点を解決し、電極中の水分がきわめて少なく、電極と集電体との接合強度が強く、接着剤中の溶剤の除去が容易であり、性能劣化の起きにくい電気二重層コンデンサ及びその製造方法を提供することを目的とする。
【０００９】
【課題を解決するための手段】
本発明は、炭素材料を主体とし、バインダとして含フッ素樹脂を含む電極を接着層を介して集電体と接合してなる電極体と、前記電極体との界面に電気二重層を形成する有機電解液と、を有する電気二重層コンデンサにおいて、前記接着層が、導電性粉末、エポキシ系樹脂、硬化剤及び沸点が１６０℃以下の溶剤を含有する導電性接着剤を硬化してなることを特徴とする電気二重層コンデンサを提供する。
【００１０】
本発明の電気二重層コンデンサにおいて、導電性接着剤に含まれるバインダ成分は、エポキシ系樹脂、硬化剤、及び低沸点の溶剤からなるエポキシ樹脂であるが、この接着剤を硬化してなる接着層は、耐熱性と機械的強度とのバランスに優れており、電極と集電体との接着力及び耐食性等にも優れた硬化樹脂である。
【００１１】
本発明で用いられるエポキシ系樹脂としては、各種のエポキシ系樹脂が使用できるが、接着力、耐熱性等の特性バランスがとれていることや、純度、作業性に優れることから、ビスフェノールＡタイプ及びビスフェノールＦタイプ等のフェノール系グリシジルエーテル型、１，６−ジヒドロキシナフタレン型、フェノールノボラック型、及びクレゾールノボラック型が好適である。
【００１２】
このような樹脂としては、例えば、商品名：エピコート８２７（油化シェルエポキシ社製）、商品名：Ｄ．Ｅ．Ｒ．３３１Ｊ（ダウケミカル日本社製）等のビスフェノールＡタイプエポキシ樹脂、商品名：エピコート８０７（油化シェルエポキシ社製）等のビスフェノールＦタイプエポキシ樹脂、商品名: ＨＰ−４０３２Ｄ（大日本インキ化学工業社製）等の１，６−ジヒドロキシナフタレンタイプエポキシ樹脂、商品名: エピコート１５４（油化シェルエポキシ社製）等のフェノールノボラックタイプエポキシ樹脂、商品名: エピコート１８０Ｈ６５（油化シェルエポキシ社製）等のクレゾールノボラックタイプエポキシ樹脂等が挙げられる。これらのエポキシ系樹脂は単独で使用しても２種以上を混合して使用してもよい。
【００１３】
本発明で用いられる硬化剤としては、エポキシ系樹脂硬化剤として通常知られているものがいずれも使用できるが、硬化物が耐熱性を有するようにジエチレントリアミン、トリエチレンテトラミン、メタフェニレンジアミン等の１級又は２級のアミノ基を２個以上含むアミン系硬化剤、又はジシアンジアミドのような潜在型硬化剤が特に好ましい。これらの硬化剤は、単独で使用してもよく、２種以上混合して使用してもよい。硬化剤の好ましい添加量はその種類によって大きく異なるが、製造工程にあわせて選択される硬化時間に合わせて適宜選択できる。
【００１４】
本発明で用いられる沸点が１６０℃以下の溶剤としては、芳香族系溶剤としてトルエン、ｏ−キシレン、ｍ−キシレン、脂肪族系溶剤としてｎ−ヘキサン、ケトン系溶剤としてメチルエチルケトン、セロソルブ系溶剤としてｎ−ブチルセロソルブ等の溶剤がエポキシ系樹脂と反応せずにエポキシ系樹脂を高濃度で溶解できるので好ましい。これらの溶剤は、単独で使用しても２種以上の混合溶剤として使用してもよく、エポキシ系樹脂を溶解して導電性接着剤が所望の粘度となるように加える。
【００１５】
また、導電性接着層に含まれるエポキシ系樹脂と硬化剤との合量の割合は、導電性粉末、エポキシ系樹脂及び硬化剤の合量に対し、１０〜７０重量％であることが好ましい。１０重量％未満では良好な接着性が得られず、一方７０重量％を超えると、導電性が急激に低下する。
【００１６】
本発明では、導電性接着層を形成するための接着剤中に、導電性粉末、エポキシ系樹脂、硬化剤及び沸点１６０℃以下の溶剤以外に、硬化触媒、カップリング剤等の表面処理剤及びその他の添加剤を必要に応じて配合してもよい。
【００１７】
硬化触媒としては、例えば２−エチル−４−メチルイミダゾール、１−ベンジル−２−フェニルイミダゾール等のイミダゾール類が、硬化を速やかに進めるために少量添加されてもよい。また、導電性粉末の樹脂との濡れ性、樹脂中への分散性を改善するために、該粉末に対し１重量％程度の脂肪酸、各種シランカップリング剤等の表面処理剤を配合して導電性粉末を表面処理してから使用してもよい。また、その他、レベリング剤、分散剤等を加えてもよい。
【００１８】
本発明において、導電性接着層に含まれる導電性粉末としては、電気化学的な耐食性を必要とされ、非金属が好ましい。特にカーボンブラックや黒鉛等の導電性炭素材料の使用が好ましい。
【００１９】
本発明の電気二重層コンデンサでは、導電性接着層のバインダ成分である、エポキシ系樹脂を硬化剤を使用して硬化させてなる、溶剤除去後のエポキシ樹脂は耐熱性が高いため、電極を集電体と接合させた後でも高温下で加熱又は減圧下で加熱処理することによって炭素材料中にある水分を充分に乾燥除去できる。また、上記バインダ成分は有機電解液に対する耐性があり、含フッ素樹脂をバインダとする電極シートと金属等の集電体との接着強度もきわめて優れる。このため、大電流密度で充放電サイクルを繰り返しても、長期間にわたって電圧を印加しても、作動性能が安定しており、電極の内部抵抗の増加を少なくできる。
【００２０】
上記バインダ成分に用いるエポキシ系樹脂は樹脂粉末又はワニスとして入手できるので、必要に応じて溶剤に溶解して溶液とし、この溶液に硬化剤と、導電性フィラーとしてカーボンブラックや黒鉛微粒子とを均一に分散させることにより懸濁液状の接着剤が得られる。この接着剤を集電体の表面に塗工し、次いでこの塗工面にあらかじめシート状に成形した電極をのせて圧着し、加熱乾燥することにより電極と集電体が一体化した電極体が得られる。
【００２１】
本発明の電気二重層コンデンサの電極の炭素材料は、比表面積が７００〜２５００ｍ2 ／ｇ、特には１０００〜２０００ｍ2 ／ｇであると容量が大きく強度も高くできるので好ましい。炭素材料としては活性炭、カーボンブラック、ポリアセン等が挙げられるが、特に活性炭粉末を使用することが好ましく、導電材として高導電性カーボンブラックを加えて使用するとさらに好ましい。この場合、導電材は電極中に５〜２０重量％含まれることが好ましい。
【００２２】
また、通常、正極、負極ともに上記電極を用いて電気二重層コンデンサを構成するが、正極又は負極の一方のみを上記電極とし、もう一方の電極に充放電可能な非分極性電極材料、すなわち二次電池用活物質材料を主成分として使用してもよい。
【００２３】
本発明における電極にはバインダとして含フッ素樹脂が含まれる。特にポリテトラフルオロエチレンは耐熱性、耐薬品性を有し、繊維化させることにより少量でも電極に強度を付与し、電極の導電性を阻害しにくいので好ましい。電極の強度と導電性のバランスの観点から、バインダは電極中に５〜２０重量％含まれることが好ましい。
【００２４】
上記の電極を電気的に接続する集電体は、導電性に優れ、かつ電気化学的に耐久性のある材料であればよく、アルミニウムやチタンやタンタル等のバルブ金属、ステンレス鋼、金や白金等の貴金属、黒鉛やグラッシーカーボンやカーボンブラックを含む導電性ゴム等の炭素系材料等が好ましく使用できる。特に軽量で導電性に優れ電気化学的に安定していることからアルミニウムが好ましい。
【００２５】
電極はシート状に成形した後、導電性接着剤を介して集電体に接合されることが好ましく、電極の作製方法としては、例えば活性炭粉末とカーボンブラックと含フッ素樹脂と液状潤滑材との混合物を混練した後圧延してシート状に成形する。得られたシート状電極はあらかじめ集電体に導電性接着剤を塗工した面の上にのせて圧着し、好ましくは１５０℃以上の高温下、さらに好ましくは減圧下で加熱乾燥することにより導電性接着剤が硬化して強固に集電体と電極を接合できる。電極体の生産性向上のためには１５０〜１７０℃で減圧乾燥することがさらに好ましい。
【００２６】
また、電極は、含フッ素樹脂を溶媒に溶解した溶液に炭素材料を分散させてスラリーとなし、該スラリーを集電体に塗工して形成してもよい。この場合もスラリーは、あらかじめ集電体に導電性接着剤を塗工した面の上に塗工し、１５０℃以上の高温下、特には減圧下で加熱乾燥することが好ましい。
【００２７】
本発明の電気二重層コンデンサに使用される有機電解液は特に限定されず、公知の有機溶媒にイオン解離性の塩類を含む有機電解液を使用できる。なかでもＲ1 Ｒ2 Ｒ3 Ｒ4 Ｎ+ 、Ｒ1 Ｒ2 Ｒ3 Ｒ4 Ｐ+ （Ｒ1 、Ｒ2 、Ｒ3 、Ｒ4 、はそれぞれ独立に炭素数１〜６のアルキル基）等の第４級オニウムカチオンと、ＢＦ4 -、ＰＦ6 -、ＣｌＯ4 -、ＣＦ3 ＳＯ3 -等のアニオンとからなる塩を有機溶媒に溶解させた有機電解液を使用するのが好ましい。
【００２８】
上記有機溶媒としては、プロピレンカーボネート、ブチレンカーボネート、ジエチルカーボネート等のカーボネート類、γ−ブチルラクトン等のラクトン類、スルホラン又はこれらの混合溶媒が好ましく使用できる。
【００２９】
【実施例】
水蒸気賦活法で得られたやしがら活性炭粉末（平均粒径１０μｍ、比表面積１８００ｍ2 ／ｇ）８０重量％、ポリテトラフルオロエチレン１０重量％及びカーボンブラック１０重量％からなる混合物にエタノールを加えて混練し、混練物をシート状に成形し、さらに厚さ０．３ｍｍにロール圧延して電極シートを作製した。このシートから４０ｍｍ角の電極シートを切り取り、これをエッチング処理を施した厚さ０．１ｍｍのアルミニウム箔集電体の表面に、以下の導電性接着剤（ａ）〜（ｈ）を介して接着固定し、それぞれ表１に示した温度にて減圧下で３時間加熱して乾燥処理し、各電極中の水分を除去した。
【００３０】
乾燥後の集電体と接合された電極体を、低湿度のアルゴンガスを充たしたグローブボックスに移し、有機電解液として１ｍｏｌ／ｌのテトラエチルアンモニウムテトラフルオロボレートを含むプロピレンカーボネート溶液を充分含浸させ、２枚の電極を間にポリプロピレン繊維の不織布からなるセパレータ紙を挟んで対向させ、電気二重層コンデンサを組み立てた。
【００３１】
得られた電気二重層コンデンサの初期の放電容量及び内部抵抗を測定した後、４０℃の恒温槽中で０〜２．８Ｖの間で１Ａの定電流による充放電を３０００サイクル繰り返し、３０００サイクル後の放電容量及び内部抵抗を測定し、サイクル試験前後の性能変化を観察することにより、電気二重層コンデンサの長期的な作動信頼性を加速的に評価した。結果を表１に示す。なお、表１において、例１〜５は本発明の実施例、例６〜８は本発明の比較例である。
【００３２】
［導電性接着剤（ａ）］
導電性カーボンブラック粉末１０ｇに、ビスフェノールＡタイプエポキシ樹脂（油化シェルエポキシ社製、商品名：エピコート８２７）を１．８ｇ、硬化剤としてジエチレントリアミン（ＤＥＴＡ）を０．２０ｇ、及び溶剤としてメチルエチルケトン（沸点８０℃）を１０ｇを充分に混合し調製した。
【００３３】
［導電性接着剤（ｂ）］
硬化剤としてジエチレントリアミンのかわりにトリエチレンテトラミンを０．２３ｇ用いた以外は導電性接着剤（ａ）と同様にして調製した。
【００３４】
［導電性接着剤（ｃ）］
硬化剤としてジエチレントリアミンのかわりにメタキシリレンジアミンを０．３０ｇ用いた以外は導電性接着剤（ａ）と同様にして調製した。
【００３５】
［導電性接着剤（ｄ）］
硬化剤としてジエチレントリアミンのかわりにジシアンジアミドを０．１０ｇを用い、溶媒としてメチルエチルケトンのかわりにメチルイソブチルケトン（沸点１１８℃）２．５ｇとｍ−キシレン（沸点１３９℃）２．５ｇとを混合して用いた以外は導電性接着剤（ａ）と同様にして調製した。
【００３６】
［導電性接着剤（ｅ）］
エポキシ系樹脂としてエピコート８２７のかわりにフェノールノボラックタイプのエピコート１５４（油化シェルエポキシ社製）を１．８ｇを用いた以外は導電性接着剤（ａ）と同様にして調製した。
【００３７】
［導電性接着剤（ｆ）］
導電性カーボンブラック粉末１０ｇに、ポリイミド樹脂（商品名：Ｕ−ワニス、宇部興産社製）を固形分として２．５ｇを混合し、さらに粘度調整のためにＮ−メチル−２−ピロリドンで希釈し調製した。
【００３８】
［導電性接着剤（ｇ）］
導電性カーボンブラック粉末１０ｇに、ポリビニルアルコール系樹脂（商品名：ゴーセノール、日本合成化学社製）を固形分として２．５ｇを混合し、さらに粘度調整のためにメチルエチルケトンで希釈し調製した。なお、ポリビニルアルコール系樹脂は耐熱性が低いため、硬化温度は１２０℃とした。
【００３９】
【表１】
【発明の効果】
本発明の電気二重層コンデンサは、充放電サイクル試験を高温で行って加速的に評価すると、導電性接着剤を比較的低い温度で硬化させたにもかかわらず、容量減少と内部抵抗の上昇が小さい。本発明によれば、長期間使用しても性能劣化が少なく、作動信頼性に優れた電気二重層コンデンサが提供できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric double layer capacitor, and more particularly to an electric double layer capacitor excellent in operation reliability.
[0002]
[Prior art]
The electric double layer capacitor is based on the principle that electric charge is accumulated in the electric double layer formed at the interface between the electrode and the electrolyte. In order to improve the capacity density of the electric double layer capacitor, the electrode has a high specific surface area. Carbon materials such as activated carbon and carbon black, fine particles of metal or conductive metal oxide, and the like are used. In order to perform charging and discharging efficiently, the electrode is bonded to a layer or foil having a low electron conductive resistance such as a metal or graphite called a current collector. The current collector is usually made of valve metal such as aluminum having high electrochemical corrosion resistance, stainless steel such as SUS304, SUS316L, or the like.
[0003]
There are two types of electric double layer capacitors, one using an organic electrolyte as the electrolyte and the other using an aqueous electrolyte. However, the organic electrolyte is used because it has a high operating voltage and can increase the energy density of the charged state. Electric double layer capacitors are attracting attention. When using an organic electrolyte, if water is present inside the electric double layer capacitor, the water will be electrolyzed and the performance will be deteriorated. Therefore, the electrode must be sufficiently dehydrated, and usually dried by heating under reduced pressure. Processing has been applied.
[0004]
Activated carbon is mainly used for the electrode, but activated carbon is usually in the form of powder, so it is mixed with a binder containing a fluorine-containing resin such as polytetrafluoroethylene (hereinafter referred to as PTFE) and formed into a sheet-like electrode. It is known to use as an electrode body electrically connected to a current collector. In many cases, the electrode and the current collector are bonded together via a conductive adhesive layer so that the electrical contact resistance is reduced. However, the fluorine-containing resin has a property that it is difficult to bond, and it is difficult to increase the bonding strength.
[0005]
Since the conductive adhesive layer is required to have electrochemical corrosion resistance, it is preferable that a non-metallic material such as carbon black or graphite is included as a filler that gives electronic conductivity. Further, various binder components are used for the conductive adhesive layer in order to ensure the bonding strength. Examples of the binder component used for this purpose include resins such as cellulose and polyvinyl alcohol (JP 59-3915, JP 62-200071), inorganic binder components such as water glass (JP 2-82608), A polyimide resin (Japanese Patent Laid-Open No. 9-270370) is known.
[0006]
However, when a conductive adhesive containing a resin-based binder component such as cellulose or polyvinyl alcohol is used, the electrode and the current collector are liable to peel off because of insufficient resistance to the organic electrolyte. In addition, since the heat resistance is around 120 ° C., it cannot be dried at a high temperature, and it is difficult to sufficiently remove the remaining moisture adsorbed on the activated carbon. There are problems such as degradation of performance.
[0007]
In addition, inorganic binders such as water glass have high heat resistance, but the adhesive strength between the electrode and the metal current collector is insufficient, and the performance of the electric double layer capacitor deteriorates due to elution of alkali components and residual moisture. There is. Polyimide resin is sufficient in terms of heat resistance and adhesiveness, but a solvent with high polarity such as N-methyl-2-pyrrolidone must be used as a solvent to dissolve the resin. There is a problem in terms of.
[0008]
[Problems to be solved by the invention]
The present invention solves the above-described problems in the prior art, the moisture in the electrode is extremely low, the bonding strength between the electrode and the current collector is strong, the solvent in the adhesive can be easily removed, and performance deterioration is unlikely to occur. An object of the present invention is to provide an electric double layer capacitor and a manufacturing method thereof.
[0009]
[Means for Solving the Problems]
The present invention forms an electric double layer at an interface between an electrode body mainly composed of a carbon material and an electrode body containing a fluorine-containing resin as a binder and bonded to a current collector through an adhesive layer. In the electric double layer capacitor having an organic electrolyte, the adhesive layer is formed by curing a conductive adhesive containing a conductive powder, an epoxy resin, a curing agent, and a solvent having a boiling point of 160 ° C. or less. An electric double layer capacitor is provided.
[0010]
In the electric double layer capacitor of the present invention, the binder component contained in the conductive adhesive is an epoxy resin composed of an epoxy resin, a curing agent, and a low boiling point solvent, and an adhesive layer formed by curing this adhesive. Is a cured resin that has an excellent balance between heat resistance and mechanical strength, and also has excellent adhesion between the electrode and the current collector, corrosion resistance, and the like.
[0011]
As the epoxy resin used in the present invention, various epoxy resins can be used. However, since the balance of properties such as adhesive strength and heat resistance is taken, and the purity and workability are excellent, bisphenol A type and Phenol-based glycidyl ether type such as bisphenol F type, 1,6-dihydroxynaphthalene type, phenol novolak type, and cresol novolak type are preferable.
[0012]
As such resin, for example, trade name: Epicoat 827 (manufactured by Yuka Shell Epoxy Co., Ltd.), trade name: D.I. E. R. Bisphenol A type epoxy resin such as 331J (made by Dow Chemical Japan), trade name: Bisphenol F type epoxy resin such as Epicoat 807 (made by Yuka Shell Epoxy), trade name: HP-4032D (Dainippon Ink Chemical Industries, Ltd.) 1,6-dihydroxynaphthalene type epoxy resin such as product): phenol novolac type epoxy resin such as Epicoat 154 (manufactured by Yuka Shell Epoxy), product name: Epicoat 180H65 (manufactured by Yuka Shell Epoxy), etc. Examples include cresol novolac type epoxy resins. These epoxy resins may be used alone or in combination of two or more.
[0013]
As the curing agent used in the present invention, any one commonly known as an epoxy resin curing agent can be used, but 1 such as diethylenetriamine, triethylenetetramine, metaphenylenediamine, etc. so that the cured product has heat resistance. Particularly preferred are amine curing agents containing two or more primary or secondary amino groups, or latent curing agents such as dicyandiamide. These curing agents may be used alone or in combination of two or more. Although the preferable addition amount of a hardening | curing agent changes greatly with the kind, it can select suitably according to the hardening time selected according to a manufacturing process.
[0014]
Solvents having a boiling point of 160 ° C. or less used in the present invention include toluene, o-xylene, m-xylene as aromatic solvents, n-hexane as aliphatic solvents, methyl ethyl ketone as ketone solvents, and n as cellosolve solvents. -Solvents such as butyl cellosolve are preferable because they can dissolve the epoxy resin at a high concentration without reacting with the epoxy resin. These solvents may be used singly or as a mixed solvent of two or more kinds, and are added so that the conductive adhesive has a desired viscosity by dissolving the epoxy resin.
[0015]
Moreover, it is preferable that the ratio of the total amount of the epoxy resin and the curing agent contained in the conductive adhesive layer is 10 to 70% by weight with respect to the total amount of the conductive powder, the epoxy resin and the curing agent. If it is less than 10% by weight, good adhesiveness cannot be obtained. On the other hand, if it exceeds 70% by weight, the conductivity rapidly decreases.
[0016]
In the present invention, in the adhesive for forming the conductive adhesive layer, in addition to the conductive powder, epoxy resin, curing agent and solvent having a boiling point of 160 ° C. or less, a surface treatment agent such as a curing catalyst and a coupling agent, and You may mix | blend another additive as needed.
[0017]
As a curing catalyst, for example, imidazoles such as 2-ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole may be added in a small amount in order to rapidly accelerate the curing. In addition, in order to improve the wettability of the conductive powder with the resin and the dispersibility in the resin, the powder is mixed with a surface treatment agent such as about 1% by weight fatty acid and various silane coupling agents. The powder may be used after surface treatment. In addition, a leveling agent, a dispersant and the like may be added.
[0018]
In the present invention, the conductive powder contained in the conductive adhesive layer is required to have electrochemical corrosion resistance, and is preferably a nonmetal. In particular, it is preferable to use a conductive carbon material such as carbon black or graphite.
[0019]
The electric double layer capacitor of the present invention, a binder component of the conductive adhesive layer, formed by curing using the curing agent of the epoxy resin, has high epoxy resin heat resistance after solvent removal, collecting electrodes Even after bonding with the electric body, the moisture in the carbon material can be sufficiently dried and removed by heating at a high temperature or heat treatment under reduced pressure. Further, the binder component has resistance to an organic electrolyte, and the adhesive strength between an electrode sheet using a fluorine-containing resin as a binder and a current collector such as a metal is extremely excellent. For this reason, even if a charge / discharge cycle is repeated at a high current density or a voltage is applied for a long period of time, the operation performance is stable, and the increase in the internal resistance of the electrode can be reduced.
[0020]
Since epoxy resins used in the binder component is available as a resin powder or varnish, optionally dissolved in a solvent to form a solution, and the curing agent to the solution, as the conductive filler of carbon black and graphite particles uniformly By dispersing it, a suspension-like adhesive is obtained. The adhesive is applied to the surface of the current collector, and then an electrode formed in advance in a sheet shape is placed on the coated surface, and the electrode is formed by integrating the electrode and the current collector by heat drying. It is done.
[0021]
Carbon material of the electric double layer capacitor electrode of the present invention has a specific surface area of 700~2500m 2 / g, preferable because particularly can higher increased strength capacity When it is 1000 to 2000 2 / g. Examples of the carbon material include activated carbon, carbon black, polyacene, and the like, but it is particularly preferable to use activated carbon powder, and it is more preferable to use high conductivity carbon black as a conductive material. In this case, the conductive material is preferably contained in the electrode in an amount of 5 to 20% by weight.
[0022]
Usually, the positive electrode and the negative electrode are both used to form an electric double layer capacitor. However, only one of the positive electrode and the negative electrode is used as the electrode, and the other electrode is a non-polarizable electrode material that can be charged and discharged. You may use the active material material for secondary batteries as a main component.
[0023]
The electrode of the present invention is Ru contains fluororesin as the binder. In particular, polytetrafluoroethylene is preferable because it has heat resistance and chemical resistance, and imparts strength to the electrode even if it is made in a small amount and hardly impedes the conductivity of the electrode. From the viewpoint of the balance between the strength of the electrode and the conductivity, the binder is preferably contained in the electrode in an amount of 5 to 20% by weight.
[0024]
The current collector for electrically connecting the above electrodes may be any material that has excellent conductivity and is electrochemically durable, such as valve metals such as aluminum, titanium, and tantalum, stainless steel, gold, and platinum. And carbon materials such as conductive rubber containing graphite, glassy carbon, or carbon black can be preferably used. Aluminum is particularly preferable because it is lightweight, excellent in electrical conductivity, and electrochemically stable.
[0025]
The electrode is preferably formed into a sheet and then joined to the current collector via a conductive adhesive. Examples of the method for producing the electrode include activated carbon powder, carbon black, fluorine-containing resin, and liquid lubricant. The mixture is kneaded and then rolled to form a sheet. The obtained sheet-like electrode is placed on the surface of the current collector coated with a conductive adhesive and pressure-bonded, and is preferably heated and dried at a high temperature of 150 ° C. or higher, more preferably under reduced pressure. The adhesive can be cured and the current collector and the electrode can be firmly bonded. In order to improve the productivity of the electrode body, it is more preferable to dry under reduced pressure at 150 to 170 ° C.
[0026]
The electrode may be formed by dispersing a carbon material in a solution obtained by dissolving a fluorine-containing resin in a solvent to form a slurry, and applying the slurry to a current collector. Also in this case, the slurry is preferably coated on the surface of the current collector coated with a conductive adhesive in advance, and dried by heating at a high temperature of 150 ° C. or higher, particularly under reduced pressure.
[0027]
The organic electrolyte used for the electric double layer capacitor of the present invention is not particularly limited, and an organic electrolyte containing ion-dissociable salts in a known organic solvent can be used. Among them, R 1 R 2 R 3 R 4 N + , R 1 R 2 R 3 R 4 P + (R 1 , R 2 , R 3 , R 4 are each independently an alkyl group having 1 to 6 carbon atoms), etc. It is preferable to use an organic electrolytic solution in which a salt composed of the quaternary onium cation and an anion such as BF 4 − , PF 6 − , ClO 4 − , CF 3 SO 3 — is dissolved in an organic solvent.
[0028]
As the organic solvent, carbonates such as propylene carbonate, butylene carbonate and diethyl carbonate, lactones such as γ-butyllactone, sulfolane or a mixed solvent thereof can be preferably used.
[0029]
【Example】
Ethanol was added to a mixture consisting of 80% by weight of activated carbon powder (average particle size 10 μm, specific surface area 1800 m 2 / g) obtained by the steam activation method, 10% by weight of polytetrafluoroethylene and 10% by weight of carbon black. Kneading was performed, the kneaded material was formed into a sheet shape, and roll-rolled to a thickness of 0.3 mm to produce an electrode sheet. A 40 mm square electrode sheet was cut out from this sheet, and this was bonded to the surface of an aluminum foil current collector having a thickness of 0.1 mm subjected to etching treatment through the following conductive adhesives (a) to (h). The sample was fixed and heated at a temperature shown in Table 1 under reduced pressure for 3 hours for drying treatment to remove moisture in each electrode.
[0030]
The electrode body joined to the dried current collector is transferred to a glove box filled with low-humidity argon gas, and sufficiently impregnated with a propylene carbonate solution containing 1 mol / l tetraethylammonium tetrafluoroborate as an organic electrolyte, An electric double layer capacitor was assembled with the two electrodes facing each other with a separator paper made of a nonwoven fabric of polypropylene fiber in between.
[0031]
After measuring the initial discharge capacity and internal resistance of the obtained electric double layer capacitor, the battery was charged and discharged with a constant current of 1 A between 0 and 2.8 V in a constant temperature bath at 40 ° C. for 3000 cycles. The long-term operational reliability of the electric double layer capacitor was acceleratedly evaluated by measuring the discharge capacity and internal resistance of the capacitor and observing the performance change before and after the cycle test. The results are shown in Table 1. In Table 1, Examples 1 to 5 are examples of the present invention, and Examples 6 to 8 are comparative examples of the present invention.
[0032]
[Conductive adhesive (a)]
10 g of conductive carbon black powder, 1.8 g of bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy, trade name: Epicoat 827), 0.20 g of diethylenetriamine (DETA) as a curing agent, and methyl ethyl ketone (boiling point) as a solvent 80 g) was prepared by thoroughly mixing 10 g.
[0033]
[Conductive adhesive (b)]
It was prepared in the same manner as the conductive adhesive (a) except that 0.23 g of triethylenetetramine was used instead of diethylenetriamine as a curing agent.
[0034]
[Conductive adhesive (c)]
It was prepared in the same manner as the conductive adhesive (a) except that 0.30 g of metaxylylenediamine was used instead of diethylenetriamine as a curing agent.
[0035]
[Conductive adhesive (d)]
Use 0.10 g of dicyandiamide instead of diethylenetriamine as a curing agent, and mix 2.5 g of methyl isobutyl ketone (boiling point 118 ° C.) and 2.5 g of m-xylene (boiling point 139 ° C.) instead of methyl ethyl ketone as a solvent. It was prepared in the same manner as the conductive adhesive (a) except that.
[0036]
[Conductive adhesive (e)]
Except that Epikote 154 of phenol novolac type instead of Epikote 827 as the epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd.) was used 1.8g was prepared in the same way the conductive adhesive and (a).
[0037]
[Conductive adhesive (f)]
2.5 g of polyimide resin (trade name: U-Varnish, manufactured by Ube Industries) is mixed with 10 g of conductive carbon black powder, and diluted with N-methyl-2-pyrrolidone for viscosity adjustment. Prepared.
[0038]
[Conductive adhesive (g)]
2.5 g of polyvinyl alcohol resin (trade name: Gohsenol, manufactured by Nippon Synthetic Chemical Co., Ltd.) as a solid content was mixed with 10 g of conductive carbon black powder, and further diluted with methyl ethyl ketone for viscosity adjustment. In addition, since polyvinyl alcohol-type resin has low heat resistance, the curing temperature was 120 degreeC.
[0039]
[Table 1]
【The invention's effect】
When the electric double layer capacitor of the present invention is evaluated at an accelerated rate by conducting a charge / discharge cycle test at a high temperature, the capacitance is reduced and the internal resistance is increased even though the conductive adhesive is cured at a relatively low temperature. small. ADVANTAGE OF THE INVENTION According to this invention, even if it uses for a long period of time, there is little performance degradation and it can provide the electrical double layer capacitor excellent in operating reliability.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09961398A JP3991437B2 (en) | 1998-04-10 | 1998-04-10 | Electric double layer capacitor and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09961398A JP3991437B2 (en) | 1998-04-10 | 1998-04-10 | Electric double layer capacitor and manufacturing method thereof |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| JPH11297579A JPH11297579A (en) | 1999-10-29 |
| JPH11297579A5 JPH11297579A5 (en) | 2005-06-16 |
| JP3991437B2 true JP3991437B2 (en) | 2007-10-17 |
Family
ID=14251953
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP09961398A Expired - Fee Related JP3991437B2 (en) | 1998-04-10 | 1998-04-10 | Electric double layer capacitor and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3991437B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE60111158T2 (en) * | 2000-09-26 | 2006-05-04 | Asahi Glass Co., Ltd. | Production method of an electrode assembly for an electric double layer capacitor |
| JP3686895B2 (en) * | 2002-11-29 | 2005-08-24 | 本田技研工業株式会社 | Method for producing electrode body for electric double layer capacitor |
| KR101449340B1 (en) | 2012-11-06 | 2014-10-13 | 현대자동차주식회사 | Manufacturing method of high temperature resistant sound absorbing materials |
-
1998
- 1998-04-10 JP JP09961398A patent/JP3991437B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11297579A (en) | 1999-10-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101420028B1 (en) | Aqueous carbon filler dispersion coating liquid, conductivity-imparting material, electrode plate for an electrical storage device, manufacturing method therefor, and electrical storage device | |
| JP3780530B2 (en) | Electric double layer capacitor and manufacturing method thereof | |
| US6072692A (en) | Electric double layer capacitor having an electrode bonded to a current collector via a carbon type conductive adhesive layer | |
| JP5596641B2 (en) | Coating liquid, conductive coating film, electrode plate for power storage device, and power storage device | |
| US7095604B2 (en) | Electrode for electric double-layer capacitor, and slurry for forming the same | |
| KR20170044185A (en) | Coating liquid, coating film, and composite material | |
| CN1839497A (en) | Electrode and its preparation method | |
| JP6121325B2 (en) | Current collector, electrode structure, non-aqueous electrolyte battery, and power storage component | |
| JP4980052B2 (en) | Electrode and manufacturing method thereof | |
| WO2002095848A1 (en) | Anode for lithium secondary battery and lithium secondary battery | |
| WO2007043515A1 (en) | Electric double layer capacitor | |
| CN101899233A (en) | A kind of supercapacitor electrode anticorrosion conductive coating | |
| CN119920634A (en) | Supercapacitor cells with high-purity binder-free carbonaceous electrodes | |
| JP3991437B2 (en) | Electric double layer capacitor and manufacturing method thereof | |
| JP2005294024A (en) | Coated collector for storage battery, its manufacturing method, and storage battery having coated collector | |
| CN103456917A (en) | Manufacturing method of electrode, and battery | |
| CN105977495A (en) | Preparation method of graphite paper for current collector of lithium-ion battery | |
| TW201943123A (en) | Energy storage device electrode and energy storage device | |
| JPH09270370A (en) | Electric double layer capacitor and method of manufacturing the same | |
| JPH11238654A (en) | Electric double layer capacitor and method of manufacturing the same | |
| CN101243528A (en) | Electric Double Layer Capacitor | |
| CN102360949A (en) | Current collector for flexible solid super capacitor and preparation method of current collector | |
| JP2001217162A (en) | Electric double layer capacitor | |
| JP2003178799A (en) | Organic electrolyte battery | |
| JP4947830B2 (en) | Method for producing electrode mixture, electrode structure using the same, and non-aqueous electrochemical device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20040921 |
|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20040921 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20070302 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20070320 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20070515 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20070703 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20070716 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100803 Year of fee payment: 3 |
|
| LAPS | Cancellation because of no payment of annual fees |