JP3861186B2 - Electric double layer capacitor - Google Patents
Electric double layer capacitor Download PDFInfo
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- JP3861186B2 JP3861186B2 JP10212496A JP10212496A JP3861186B2 JP 3861186 B2 JP3861186 B2 JP 3861186B2 JP 10212496 A JP10212496 A JP 10212496A JP 10212496 A JP10212496 A JP 10212496A JP 3861186 B2 JP3861186 B2 JP 3861186B2
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- 239000003990 capacitor Substances 0.000 title claims description 8
- 239000000835 fiber Substances 0.000 claims description 44
- 239000003365 glass fiber Substances 0.000 claims description 43
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 13
- 239000011255 nonaqueous electrolyte Substances 0.000 claims description 8
- 239000011230 binding agent Substances 0.000 claims description 4
- 239000006229 carbon black Substances 0.000 claims description 4
- 238000000034 method Methods 0.000 description 12
- 239000000123 paper Substances 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 7
- 239000007788 liquid Substances 0.000 description 7
- 230000000704 physical effect Effects 0.000 description 7
- -1 polyethylene Polymers 0.000 description 7
- 230000014759 maintenance of location Effects 0.000 description 6
- 239000003792 electrolyte Substances 0.000 description 5
- 239000008151 electrolyte solution Substances 0.000 description 5
- 239000004745 nonwoven fabric Substances 0.000 description 5
- 238000010521 absorption reaction Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- MKYBYDHXWVHEJW-UHFFFAOYSA-N N-[1-oxo-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propan-2-yl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(C(C)NC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 MKYBYDHXWVHEJW-UHFFFAOYSA-N 0.000 description 3
- 240000000907 Musa textilis Species 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- HXJUTPCZVOIRIF-UHFFFAOYSA-N sulfolane Chemical compound O=S1(=O)CCCC1 HXJUTPCZVOIRIF-UHFFFAOYSA-N 0.000 description 2
- ZZXUZKXVROWEIF-UHFFFAOYSA-N 1,2-butylene carbonate Chemical compound CCC1COC(=O)O1 ZZXUZKXVROWEIF-UHFFFAOYSA-N 0.000 description 1
- 125000003903 2-propenyl group Chemical group [H]C([*])([H])C([H])=C([H])[H] 0.000 description 1
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910017008 AsF 6 Inorganic materials 0.000 description 1
- 229910020366 ClO 4 Inorganic materials 0.000 description 1
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 1
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 150000005676 cyclic carbonates Chemical class 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001962 electrophoresis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 1
- 239000011152 fibreglass Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000002655 kraft paper Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 239000005486 organic electrolyte Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000012209 synthetic fiber Substances 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/54—Electrolytes
- H01G11/58—Liquid electrolytes
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Electric Double-Layer Capacitors Or The Like (AREA)
Description
【0001】
【発明の属する技術】
本発明は、内部抵抗が小さく、かつ電圧保持性を改良した電気二重層キャパシタ(以下EDLCという)に関する。
【0002】
【従来の技術】
従来、電気二重層キャパシタのセパレータとしては電解紙、ポリエチレン不織布、ポリプロピレン不織布、ポリエステル不織布、クラフト紙、マニラ麻シート、ガラス繊維シートが知られている(特開平1−283811号公報、特開平1−304719号公報等)。セパレータの役割は、分極性電極間を電気的に絶縁することと、充放電に伴って起きる電解液中のイオンの移動を円滑化することにある。
【0003】
最近では大電流充放電用のEDLCが注目されているが、従来のEDLCで使用されている公知のセパレータでは、電解液の吸液性と、保液性が低かった。その結果イオン伝導性が低くなり内部抵抗が大きくなってしまい、EDLCで可能な特性の一つである瞬時の大電流放電を行うと電圧降下が大きくなり、実用的でなかった。さらに、電解液の吸液性と保液性が低いことにより、セパレータがドライアップして性能劣化を引き起こすことがあった。一方、ガラス繊維シートを用いたセパレータは有機繊維に比べて一般には繊維径が細く、電解液に対する濡れ性に優れるため吸液性と保液性が高い。このようなガラス繊維シートのセパレータを用いると、イオン伝導性が大きいのでキャパシタの内部抵抗を低くできる。また、ガラス繊維は高温になっても合成繊維のように溶けないので、セパレータの融解による内部ショートが起こらないなどの利点を有する。しかしながら、従来のガラス繊維シートを構成するガラス繊維は、繊維径が10μm以上のものが主体であり、このようなガラス繊維シートのセパレータも保液性と吸液性の点で十分でなく、セパレータのドライアップによる性能劣化のおそれが依然としてあった。
【0004】
さらに、太い繊維のガラス繊維シートのセパレータでは内部にある空隙の細孔が大きいため、分極性電極に用いる活性炭の微粒子がセパレータを容易に通過できる。このため、帯電した活性炭粒子が電気泳動によって対極側に移動することがあり、その結果、電荷を失う自己放電が起きた。
【0005】
【発明が解決しようとする課題】
本発明の目的は、従来技術における上記問題点を解消しようとするものであり、内部抵抗が低く、電解液の吸液性と保液性に優れ、かつ電圧保持性を向上させたEDLCを提供することにある。
【0006】
【課題を解決するための手段】
上記目的を達成するため、請求項1に記載された発明は、活性炭、カーボンブラック及びバインダーからなる一対の分極性電極の間にセパレータを配置した素子に非水系電解液を含浸させてなるEDLCにおいて、セパレータがガラス繊維シートであって、前記ガラス繊維シートが繊維径1μm以下のガラス繊維を2〜45重量%含み、平均繊維径が0.5〜5μmであり、かつ最大繊維径が10μm以下であることを特徴とする。
【0007】
請求項2の発明は、請求項1のEDLCにおいて、前記ガラス繊維シートが、目付量10〜50g/m2、空孔率70〜90%及び厚み30〜200μmを有することとした。
【0008】
請求項3の発明は、請求項1又は2のEDLCにおいて、前記ガラス繊維シートを、ガラス短繊維の抄造紙とした。
【0009】
【発明の実施の形態】
本発明にかかるEDLCは、一対の分極性電極の間にセパレータを配置した素子に非水系電解液を含浸させてなるものである。分極性電極は、陽極、陰極とも一般的に用いられているものを採用することができる。すなわち、例えば活性炭、カーボンブラック及びバインダーとからなるシート状の分極性電極を用いることができる。
【0010】
セパレータのガラス繊維シートは、繊維径1μm以下のガラス繊維を2〜45重量%含む。かかるガラス繊維シートは、電解液の吸液性と保液性に優れており、その結果内部抵抗の小さいEDLCが得られる。
【0011】
ガラス繊維の繊維径は、最大10μm以下のものを使用するのが好ましく、平均繊維径としては、好ましくは0.5〜5μmが適当である。更に、内部抵抗を小さくするには、繊維径1μm以下のガラス繊維が5重量%以上含まれるものが好ましく、一方、ガラス繊維シートのセパレータの機械的強度を保つためと、セパレータを横切る正負極間のマイクロショートを防ぐため、本発明では、繊維径1μm以下のガラス繊維を45重量%以下含むものを使用する。
【0012】
ガラス繊維シートの目付量は、好ましくは200g/m2 以下であるが、内部抵抗を小さくするため、特には10〜50g/m2 のものが好ましい。目付量が大きいとEDLCの内部抵抗が大きくなり、高出力が得られなくなり、小さいと強度が低下する。また、空孔率は、好ましくは70〜90%にせしめられる。
本発明で使用されるガラス繊維シートは、好ましくは既知の抄造法で製造される抄造紙が好ましい。ガラス繊維は、火炎法、遠心法などで製造された比較的長さの短いガラス短繊維が使用される。ガラス繊維は、通常水溶液に必要に応じてバインダーを添加して分散させた状態で抄造機に供給され、抄造される。
【0013】
セパレータの厚さは、好ましくは1mm以下であるが、EDLCの内部抵抗を小さくするため特には、30μm〜0.2mmのものが好ましい。厚くなるとEDLCの内部抵抗が大きくなり、高出力が得られなくなり、薄くなると強度が低下する。
【0014】
EDLCに用いられる電解液には水系と有機電解液などの非水系電解液があるが、耐電圧は前者で約0.8V、後者で約2.5Vである。EDLCの静電エネルギーは耐電圧の二乗に比例するので、水系と非水系電解液を比較すると後者の方が約9倍エネルギ密度を大きくでき、有利である。
【0015】
非水系電解液に使用される電解質としては、リチウム、ナトリウムなどのアルカリ金属カチオンやアルカリ土類金属カチオン、又はR1 R2 R3 R4 N+ 、R1 R2 R3 R4 P+ (R1 、R2 、R3 、R4 はCn H2n+1で表わされるアルキル基又はアリル基、R1 、R2 、R3 、R4 は同じであっても異なってもよい)などの第4級オニウムカチオンと、BF4 - 、PF6 - 、Cl- 、CF3 SO3 - 、AsF6 - 、N(SO2 CF3 )2 - 、NO3 - 、Br- 、SO4 2- 、ClO4 - 等のアニオンとの塩が好ましい。
【0016】
また、非水系電解液に使用される有機溶媒としては、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネートなどの環状カーボネート、ジメチルカーボネート、エチルメチルカーボネート、ジエチルカーボネートなどの直鎖状カーボネート、スルホランもしくはスルホラン誘導体又はこれらの二種以上の混合溶媒が好適である。
【0017】
【実施例】
つぎに、実施例と比較例により本発明をさらに具体的に説明するが、本発明はこれら実施例により限定されるものではない。
【0018】
実施例1
本実施例は図1に示すコイン型EDLCについて行った。このEDLCの素子では、一対の分極性電極1、5の間にセパレータ8を配置している。分極性電極1、5を導電性接着剤2で金属容器のケース3と蓋4に接合し、乾燥後非水系電解液7を含浸させ、ケース3と蓋4からなる金属容器に収納した。ケース3と蓋4は、絶縁パッキング9を介してかしめ、密封した。
【0019】
本実施例では、セパレータ8のガラス繊維シートとして、ガラス短繊維の抄造紙を用いた。その繊維径は繊維径1μm以下のガラス繊維が8重量%、平均繊維径約2.3μm、最大繊維径約5μm、厚さ約160μm、目付量36.4g/m2 、空孔率76.2%であった。分極性電極としては陽極、陰極とも活性炭80wt%、カーボンブラック10wt%、ポリテトラフルオロエチレン10wt%からなる厚さ0.5mmのシート状分極性電極(活性炭の比表面積1500m2 /g、電極直径1.2mm)を用いた。これらセパレータと分極性電極からなる素子に含浸させる非水系電解液は、1.0モル/リットル濃度のテトラエチルアンモニウムテトラフルオロボレートのプロピレンカーボネート溶液を用いた。このEDLCの初期の内部抵抗と放電容量を測定し、2.5Vに30分かけて充電後、開回路にして50時間後の電圧を測定した。その後、70℃の恒温槽中において2.5Vの電圧を1000時間印加し、再び内部抵抗と放電容量を測定した。なお、内部抵抗と放電容量を測定する時の電流は0.2mAに設定した。
【0020】
実施例2
セパレータとして次の物性を有するガラス短繊維の抄造紙を用いた。その繊維径は繊維径1μm以下のガラス繊維が25重量%、平均繊維径約1.45μm、最大繊維径約5μm、厚さ約160μm、目付量34.2g/m2 、空孔率77.6%であった。このセパレータを用い、他は実施例1と同様にして行った。
【0021】
実施例3
セパレータとして次の物性を有するガラス短繊維抄造紙を用いた。その繊維径は繊維径1μm以下のガラス短繊維が40重量%、平均繊維径約1.28μm、最大繊維径約5μm、厚さ約160μm、目付量31.3g/m2 、空孔率78.3%であった。このセパレータを用い、他は実施例1と同様にして行った。
【0022】
実施例4
セパレータとして次の物性を有するガラス短繊維抄造紙を用いた。その繊維径は繊維径1μm以下のガラス繊維が3重量%、平均繊維径約2.48μm、最大繊維径約5μm、厚さ約160μm、目付量36.8g/m2 、空孔率76.0%であった。このセパレータを用い、他は実施例1と同様にして行った。
【0023】
比較例1
セパレータとして次の物性を有するガラス短繊維抄造紙を用いた。その繊維径は繊維径1μm以下のガラス繊維が50重量%、平均繊維径約1.11μm、最大繊維径約5μm、厚さ約160μm、目付量31.0g/m2、空孔率78.5%であった。このセパレータを用い、他は実施例1と同様にして行った。
【0024】
比較例2
セパレータとして次の物性を有するポリプロピレン不織布を用いた。この不織布の平均繊維径は約2.5μm、厚さ約150μm、目付量50.8g/m2、空孔率57.4%であった。このセパレータを用い、他は実施例1と同様にして行った。
【0025】
比較例3
セパレータとして次の物性を有するマニラ麻シートを用いた。このシートの繊維径は約20μm、厚さ約70μm、目付量28.1g/m2、空孔率52.4%であった。このセパレータを用い、他は実施例1と同様にして行った。
【0026】
比較例4
セパレータとして次の物性を有するガラス繊維抄造紙を用いた。その繊維径は繊維径1μm以下のガラス繊維が65重量%、平均繊維径約1.01μm、最大繊維径約5μm、厚さ約160μm、目付量30.1g/m2、空孔率79.2%であった。このセパレータを用い、他は実施例1と同様にして行った。
【0027】
なお、実施例1〜4と比較例1、4で使用したガラス短繊維抄造紙は、いずれもSiO265wt%、Na2O16wt%、B2O36wt%、CaO6wt%、Al2O34wt%、MgO3wt%の組成を有するガラスを火炎吹飛ばし法で繊維化した短繊維を、水中に分散させ、抄造法で抄紙したものである。
【0028】
実施例1〜4、及び比較例1〜4の初期の内部抵抗と放電容量、2.5Vに30分かけて充電後開回路にして50時間経過後の電圧、70℃の恒温槽中において2.5Vの電圧を1000時間印加した後の内部抵抗と容量の変化率の測定結果を表1にまとめて示す。
【0029】
【表1】
【0030】
表1より、内部抵抗、電圧保持及び放電容量変化率の点で本発明にかかるEDLCの特性が優れていることが分かる。
【0031】
【発明の効果】
上記から明らかなように、本発明によれば、内部抵抗が低く、電圧保持性の向上したEDLCが提供される。本発明にかかるEDLCは、コイン型EDLCのような比較的小さなサイズから、放電容量が50〜20000F、又は放電電流が1A〜1000Aの超大容量、大電流向けのEDLCに好適である。
【図面の簡単な説明】
【図1】本発明にかかるコイン型EDLCの実施例の一例を概念的に示す縦断面図である。
【符号の説明】
1、5 分極性電極
2 導電性接着剤
3 金属容器のケース
4 金属容器の蓋
7 電解液
8 セパレータ
9 絶縁パッキング[0001]
[Technology to which the invention belongs]
The present invention relates to an electric double layer capacitor (hereinafter referred to as EDLC) having a small internal resistance and an improved voltage holding property.
[0002]
[Prior art]
Conventionally, electrolytic paper, polyethylene nonwoven fabric, polypropylene nonwoven fabric, polyester nonwoven fabric, kraft paper, Manila hemp sheet, and glass fiber sheet are known as separators for electric double layer capacitors (JP-A-1-283811, JP-A-1-304719). Issue gazette). The role of the separator is to electrically insulate the polarizable electrodes and to facilitate the movement of ions in the electrolytic solution that accompanies charging / discharging.
[0003]
Recently, attention has been paid to EDLC for charging / discharging large currents. However, known separators used in conventional EDLC have low electrolyte absorption and liquid retention. As a result, the ionic conductivity is lowered and the internal resistance is increased. When an instantaneous large current discharge, which is one of the characteristics possible with EDLC, is performed, the voltage drop increases, which is not practical. Furthermore, due to the low liquid absorbency and liquid retention of the electrolyte, the separator may dry up and cause performance degradation. On the other hand, a separator using a glass fiber sheet generally has a smaller fiber diameter than organic fibers and excellent wettability with respect to an electrolytic solution, and thus has high liquid absorption and liquid retention. When such a glass fiber sheet separator is used, the internal resistance of the capacitor can be lowered because of its high ionic conductivity. Further, since glass fiber does not melt like synthetic fiber even at high temperature, there is an advantage that an internal short circuit due to melting of the separator does not occur. However, the glass fibers constituting the conventional glass fiber sheet are mainly those having a fiber diameter of 10 μm or more, and such a glass fiber sheet separator is not sufficient in terms of liquid retention and liquid absorption. There was still a risk of performance degradation due to dry-up.
[0004]
Further, since the thick fiber glass fiber sheet separator has large pores inside, the activated carbon particles used for the polarizable electrode can easily pass through the separator. For this reason, the charged activated carbon particles may move to the counter electrode side by electrophoresis, and as a result, self-discharge that loses charge occurs.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems in the prior art, and provides an EDLC having a low internal resistance, excellent electrolyte absorption and retention, and improved voltage retention. There is to do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is an EDLC in which a non-aqueous electrolyte is impregnated in a device in which a separator is disposed between a pair of polarizable electrodes made of activated carbon, carbon black, and a binder . , the separator is a glass fiber sheet, the glass fiber sheet 2 to 45 wt% observed including the following glass fiber fiber diameter 1 [mu] m, an average fiber diameter of 0.5 to 5 [mu] m, and the maximum fiber diameter of 10μm or less It is characterized by being.
[0007]
The invention of claim 2 is the EDLC of claim 1, wherein the glass fiber sheet, eyes with weight 10 to 50 g / m 2, was to have a porosity of 70% to 90% and a thickness 30 to 200 [mu] m.
[0008]
A third aspect of the present invention is the EDLC of the first or second aspect , wherein the glass fiber sheet is a papermaking paper with short glass fibers.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The EDLC according to the present invention is obtained by impregnating a non-aqueous electrolyte into an element in which a separator is disposed between a pair of polarizable electrodes. As the polarizable electrode, those commonly used for the anode and the cathode can be employed. That is, for example, a sheet-like polarizable electrode made of activated carbon, carbon black, and a binder can be used.
[0010]
The glass fiber sheet of the separator contains 2 to 45 % by weight of glass fiber having a fiber diameter of 1 μm or less. Such a glass fiber sheet is excellent in the liquid-absorbing property and liquid-retaining property of the electrolytic solution, and as a result, an EDLC having a low internal resistance can be obtained.
[0011]
The fiber diameter of the glass fiber is preferably 10 μm or less, and the average fiber diameter is preferably 0.5 to 5 μm. Furthermore, in order to reduce the internal resistance, it is preferable that glass fiber having a fiber diameter of 1 μm or less is contained in an amount of 5% by weight or more, while maintaining the mechanical strength of the glass fiber sheet separator and between the positive and negative electrodes crossing the separator. to prevent micro-short, in the present invention, to use those containing the following glass fiber fiber diameter 1 [mu] m 45 wt% or less.
[0012]
Basis weight of the glass fiber sheet is preferably although 200 g / m 2 or less, in order to reduce the internal resistance, especially preferably from 10 to 50 g / m 2. If the weight per unit area is large, the internal resistance of the EDLC increases, and a high output cannot be obtained. The porosity is preferably 70 to 90%.
The glass fiber sheet used in the present invention is preferably papermaking paper produced by a known papermaking method. As the glass fiber, a short glass fiber having a relatively short length manufactured by a flame method, a centrifugal method, or the like is used. Glass fibers are usually supplied to a papermaking machine in a state where a binder is added and dispersed in an aqueous solution as necessary, and papermaking is performed.
[0013]
The thickness of the separator is preferably 1 mm or less, but is preferably 30 μm to 0.2 mm in order to reduce the internal resistance of the EDLC. As the thickness increases, the internal resistance of the EDLC increases, and a high output cannot be obtained. When the thickness decreases, the strength decreases.
[0014]
Electrolytic solutions used in EDLC include nonaqueous electrolytic solutions such as aqueous and organic electrolytes, but the withstand voltage is about 0.8 V in the former and about 2.5 V in the latter. Since the electrostatic energy of EDLC is proportional to the square of the withstand voltage, comparing the aqueous and non-aqueous electrolytes, the latter can advantageously increase the energy density by about 9 times.
[0015]
Examples of the electrolyte used for the non-aqueous electrolyte include alkali metal cations such as lithium and sodium, alkaline earth metal cations, R 1 R 2 R 3 R 4 N + , R 1 R 2 R 3 R 4 P + ( R 1 , R 2 , R 3 and R 4 are alkyl groups or allyl groups represented by C n H 2n + 1 , and R 1 , R 2 , R 3 and R 4 may be the same or different. Quaternary onium cations, BF 4 − , PF 6 − , Cl − , CF 3 SO 3 − , AsF 6 − , N (SO 2 CF 3 ) 2 − , NO 3 − , Br − , SO 4 2−. , ClO 4 - salt of the anion of the like are preferable.
[0016]
Examples of the organic solvent used in the non-aqueous electrolyte include cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate, linear carbonates such as dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate, sulfolane or sulfolane derivatives, or these A mixed solvent of two or more of these is preferred.
[0017]
【Example】
Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.
[0018]
Example 1
In this example, the coin type EDLC shown in FIG. 1 was used. In this EDLC element, a
[0019]
In this example, a papermaking paper of short glass fibers was used as the glass fiber sheet of the
[0020]
Example 2
As the separator, paper short fiber paper having the following physical properties was used. The fiber diameter is 25% by weight of glass fiber having a fiber diameter of 1 μm or less, the average fiber diameter is about 1.45 μm, the maximum fiber diameter is about 5 μm, the thickness is about 160 μm, the basis weight is 34.2 g / m 2 , and the porosity is 77.6. %Met. Other than using this separator, the same procedure as in Example 1 was performed.
[0021]
Example 3
A short glass fiber paper having the following physical properties was used as a separator. The fiber diameter is 40% by weight of short glass fibers having a fiber diameter of 1 μm or less, the average fiber diameter is about 1.28 μm, the maximum fiber diameter is about 5 μm, the thickness is about 160 μm, the basis weight is 31.3 g / m 2 , and the porosity is 78. 3%. Other than using this separator, the same procedure as in Example 1 was performed.
[0022]
Example 4
A short glass fiber paper having the following physical properties was used as a separator. The fiber diameter is 3% by weight of glass fiber having a fiber diameter of 1 μm or less, the average fiber diameter is about 2.48 μm, the maximum fiber diameter is about 5 μm, the thickness is about 160 μm, the basis weight is 36.8 g / m 2 , and the porosity is 76.0. %Met. Other than using this separator, the same procedure as in Example 1 was performed.
[0023]
Comparative Example 1
A short glass fiber paper having the following physical properties was used as a separator. The fiber diameter is 50% by weight of glass fiber having a fiber diameter of 1 μm or less, the average fiber diameter is about 1.11 μm, the maximum fiber diameter is about 5 μm, the thickness is about 160 μm, the basis weight is 31.0 g / m 2 , and the porosity is 78.5. %Met. Other than using this separator, the same procedure as in Example 1 was performed.
[0024]
Comparative Example 2
A polypropylene nonwoven fabric having the following physical properties was used as a separator. This nonwoven fabric had an average fiber diameter of about 2.5 μm, a thickness of about 150 μm, a basis weight of 50.8 g / m 2 , and a porosity of 57.4%. Other than using this separator, the same procedure as in Example 1 was performed.
[0025]
Comparative Example 3
A Manila hemp sheet having the following physical properties was used as a separator. The fiber diameter of this sheet was about 20 μm, the thickness was about 70 μm, the basis weight was 28.1 g / m 2 , and the porosity was 52.4%. Other than using this separator, the same procedure as in Example 1 was performed.
[0026]
Comparative Example 4
A glass fiber paper having the following physical properties was used as a separator. The fiber diameter is 65% by weight of glass fiber having a fiber diameter of 1 μm or less, the average fiber diameter is about 1.01 μm, the maximum fiber diameter is about 5 μm, the thickness is about 160 μm, the basis weight is 30.1 g / m 2 , and the porosity is 79.2. %Met. Other than using this separator, the same procedure as in Example 1 was performed.
[0027]
The glass short fiber papermaking sheet used in Comparative Examples 1 and 4 of Example 1-4 are both SiO 2 65wt%, Na 2 O16wt %, B 2 O 3 6wt%, CaO6wt%, Al 2 O 3 4wt %, MgO 3 wt% of a short fiber obtained by fiberizing by a flame blowing method is dispersed in water and paper is made by a paper making method.
[0028]
Example 1-4 2, and the initial internal resistance and the discharge capacity of Comparative Example 1-4, the voltage after 50 hours have passed in the open circuit after charging over 30 minutes to 2.5V, at a constant temperature bath at 70 ° C. Table 1 summarizes the measurement results of the rate of change in internal resistance and capacitance after applying a voltage of .5 V for 1000 hours.
[0029]
[Table 1]
[0030]
From Table 1, it can be seen that the characteristics of the EDLC according to the present invention are excellent in terms of internal resistance, voltage holding, and discharge capacity change rate.
[0031]
【The invention's effect】
As is apparent from the above, according to the present invention, an EDLC having a low internal resistance and an improved voltage holding property is provided. The EDLC according to the present invention is suitable for an EDLC for a large current and a very large capacity having a discharge capacity of 50 to 20000 F or a discharge current of 1 A to 1000 A from a relatively small size like a coin-type EDLC.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view conceptually showing an example of an embodiment of a coin-type EDLC according to the present invention.
[Explanation of symbols]
1, 5 Polarized electrode 2 Conductive adhesive 3 Metal container case 4 Metal container lid 7
Claims (3)
Priority Applications (1)
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JP10212496A JP3861186B2 (en) | 1996-04-24 | 1996-04-24 | Electric double layer capacitor |
Applications Claiming Priority (1)
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JP10212496A JP3861186B2 (en) | 1996-04-24 | 1996-04-24 | Electric double layer capacitor |
Publications (2)
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JPH09289140A JPH09289140A (en) | 1997-11-04 |
JP3861186B2 true JP3861186B2 (en) | 2006-12-20 |
Family
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JP10212496A Expired - Fee Related JP3861186B2 (en) | 1996-04-24 | 1996-04-24 | Electric double layer capacitor |
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Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2003168629A (en) * | 2001-08-30 | 2003-06-13 | Mitsubishi Paper Mills Ltd | Separator for capacitor |
JP2006024611A (en) | 2004-07-06 | 2006-01-26 | Nisshinbo Ind Inc | Electric double layer capacitor |
JP4892371B2 (en) * | 2007-02-19 | 2012-03-07 | セイコーインスツル株式会社 | Electric double layer capacitor |
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1996
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