JP4833504B2 - Electrochemical capacitor and hybrid power supply comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical capacitor having a high capacity and excellent cycle characteristics, and provide a hybrid power source constituted of the electrochemical capacitor which is small in size, less in the occurrence of overcharge, has a high capacity, and is durable for a long-term use. <P>SOLUTION: The electrochemical capacitor is constituted of a positive electrode using a carbonaceous material capable of the absorption and desorption of an anion, a negative electrode, and an organic electrolyte solution containing lithium salt as an electrolyte. By using a lithium titanic oxide having a ramsdellite type crystal structure to a negative electrode to set a capacity ratio between the negative electrode and positive electrode at the negative electrode/the positive electrode of 1-7, the electrochemical capacitor is constructed. The hybrid power source is constituted by connecting the electrochemical capacitor and a battery in parallel. As the lithium titanic oxide having the ramsdellite type crystal structure, that expressed by a Li<SB>2</SB>Ti<SB>3</SB>O<SB>7</SB>is preferable, and as the ratio of the negative electrode/the positive electrode, that of the negative electrode/the positive electrode 1.5-5 is preferable. <P>COPYRIGHT: (C)2004,JPO&amp;NCIPI

Description

【００８６】
上記のようにして求めた容量保持率を、負極と正極の容量比、負極のリチウムチタン酸化物の結晶構造、１サイクル目の放電容量と共に、表１に示す。
【００８７】
【表１】

【００８８】
表１に示すように、実施例１〜３の電気化学キャパシタは、比較例１〜３の電気化学キャパシタに比べて、１サイクル目の放電容量が大きく、かつ１００００サイクル目の容量保持率が大きく、高容量で、かつサイクル特性が優れていた。すなわち、負極にラムスデライト型の結晶構造を有するリチウムチタン酸化物を用い、負極と正極の容量比を負極／正極＝１〜７の範囲内にした実施例１〜３の電気化学キャパシタは、高容量で、かつサイクル特性が優れていたが、同じ結晶構造を持つリチウムチタン酸化物を用いても、負極と正極の容量比が負極／正極＝１〜７の範囲外の比較例１〜２の電気化学キャパシタは、実施例１〜３の電気化学キャパシタに比べて、容量が小さく、かつサイクル特性が劣っていた。
【００８９】
また、同じリチウムチタン酸化物であってもスピネル形の結晶構造を有するリチウムチタン酸化物を負極に用いた比較例３の電気化学キャパシタは、容量こそ実施例１〜３の電気化学キャパシタに近い大きさであるものの、サイクル特性が実施例１〜３の電気化学キャパシタに比べて著しく劣っていた。つまり、同じリチウムチタン酸化物を用いても、ラムスデライト型の結晶構造を有するリチウムチタン酸化物を負極に用いた場合は、スピネル型の結晶構造を有するリチウムチタン酸化物を負極に用いた場合に比べて、サイクル特性が大幅に改善された電気化学キャパシタが得られることが明らかであった。
【００９０】
以上のように、本発明によれば、高容量で、かつサイクル特性が優れた電気化学キャパシタを提供することができる。
【００９１】
つぎに、ハイブリッド電源に関する実施例４〜６と比較例４〜７について説明する。
【００９２】
実施例４
化学式Ｌｉ₂ Ｔｉ₃ Ｏ₇ で表され、レーザー回折・散乱法を用いた粒度分布測定による平均粒子径が０．６μｍであり、ＣｕをターゲットとしたＸ線回折法によるメインピークのｄ値が０．４４５ｎｍ、０．２６９ｎｍ、０．２２４ｎｍ、０．１７７ｎｍであるリチウムチタン酸化物６０質量部に、アセチレンブラック３質量部と７０％のポリテトラフルオロエチレンを含むディスパージョン水溶液をポリテトラフルオロエチレンが１０質量部になるように加えて混練し、得られた負極合剤含有ペーストを厚さ１５μｍ、幅２００ｍｍのアルミニウム箔の両面に塗布し、１２０℃で乾燥して、負極合剤層を形成した後、３ｔｏｎ／ｃｍ² でプレス処理して、負極をを作製した。
【００９３】
得られた負極の厚みは７０μｍで、負極合剤層の形成量（ただし、単位平方センチメートル当たりの負極合剤層の形成量をいう。以下同様）は両面とも７．８ｍｇ／ｃｍ² であった。これを片面の面積が２ｃｍ² になるように切り出したものを作用極とし、対極および参照極を金属リチウムを用い、有機電解液には１．５ＭＬｉＰＦ₆ ／ＥＣ＋ＤＥＣ〔エチレンカーボネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）との混合溶媒にＬｉＰＦ₆ を１．５ｍｏｌ／ｌ溶解させて調製した有機電解液〕を用いて、３電極式電気化学セルで、充放電電圧１〜２．５Ｖ、電流密度０．５ｍＡ／ｃｍ² で容量を測定したときの負極の単位質量当たりの容量は１００ｍＡｈ／ｇであった。ただし、上記における負極の質量とは、負極合剤の質量を意味し、集電体であるアルミニウム箔の質量は含まない。
【００９４】
正極にはフェノール樹脂を炭化し水酸化カリウム水溶液中で賦活処理した平均粒径１５μｍである活性炭を用いた。なお、この活性炭は窒素吸着によるＢＥＴ比表面積が３２００ｍ² ／ｇであり、ミクロ孔の細孔容積が１．０ｃｃ／ｇで、メソ孔の細孔容積が０．７ｃｃ／ｇであり、全細孔容積に対するミクロ孔の細孔容積の存在比率が６０％で、全細孔容積に対するメソ孔の細孔容積の存在比率が３９％であった。
【００９５】
この活性炭９０質量部に、アセチレンブラック５質量部を加え、さらに７０％のポリテトラフルオロエチレンを含むディスパージョン水溶液をポリテトラフルオロエチレンが５質量部となるように加えて混練し、得られた正極合剤含有ペーストを厚さ１５μｍのアルミニウム箔の両面に塗布し、１２０℃で乾燥して正極合剤層を形成した後、３ｔｏｎ／ｃｍ² でプレス処理して、正極を作製した。
【００９６】
得られた正極の厚みは９０μｍで、正極合剤層の形成量は両面とも２．０ｍｇ／ｃｍ² であった。これを片面の面積が２ｃｍ² になるように切り出したものを作用極とし、前記負極の場合と同様に３電極式電気化学セルで容量を測定した。充電カット電圧を４．５Ｖ、放電カット電圧３Ｖ、電流密度を０．５ｍＡ／ｃｍ² としたときの正極の単位質量当たりの容量は８０ｍＡｈ／ｇであった。ただし、上記における正極の質量とは、正極合剤の質量を意味し、集電体であるアルミニウム箔の質量は含まない。
【００９７】
前記負極を幅４０ｍｍ、長さ３２０ｍｍに切り出し、正極を幅４０ｍｍ、長さ３１０ｍｍに切り出し、それぞれの中央にアルミニウムのタブを溶接し、それらを電気化学キャパシタ構成用の負極および正極とした。
【００９８】
上記負極および正極を厚さ２５μｍの微孔性ポリエチレンフィルムからなるセパレータを介して巻回し、直径９．５ｍｍ、長さ４０ｍｍの巻回体を得た。この巻回体を直径１０ｍｍ、高さ４５ｍｍの円筒缶に装填した。アルゴンガス雰囲気のドライボックス内で、プロピレンカーボネートとジエチルカーボネートとを１：２（体積比）で混合した混合溶媒にＬｉＰＦ₆ を１．５モル／リットルの濃度になるように溶解させた有機電解液を前記円筒缶に注入し、厚さ５ｍｍのブチルゴム製の封止体で円筒缶の開放部を閉塞し、かしめて円筒形の電気化学キャパシタを作製した。なお、この円筒形電気化学キャパシタにおける負極と正極との容量比は負極／正極＝５であった。
【００９９】
上記のように作製した電気化学キャパシタを、３０ｍＡの定電流で充電カット電圧３．５Ｖ、放電カット電圧１．０Ｖの条件で充放電させて初回の放電容量を測定したところ、４５ｍＡｈの放電容量が得られた。上記と同じ充放電条件で１００００サイクルまで充放電を繰り返し、その１００００サイクル目の放電容量を測定した。その結果を後記の表２に示す。
【０１００】
つぎに、上記のように作製した円筒形の電気化学キャパシタを、セルを６直列接続してなる結晶質シリコン太陽電池のモジュール（出力０．２２Ｗ、電圧３．３Ｖ、大きさ５０×５５ｍｍ）に電線を介して並列に接続してハイブリッド電源を作製した。
【０１０１】
上記のように作製したハイブリッド電源の太陽電池に、８０℃の温度下で、照度５０，０００ルクスの照明下で１時間照射した。その後は、それ以上に発電しないように太陽電池に黒色布をかぶせ、外部電源を接続して１０ｍＡの定電流放電をし、放電カット電圧を１Ｖとして、放電容量を測定した。得られた放電容量を後記の表３に示す。
【０１０２】
以上の操作を初期の放電容量に対して６０％の容量になるまで繰り返し、繰り返しが可能なサイクル数を調べた。その結果を後記の表３に示す。
【０１０３】
実施例５
活性炭に代えてアーク放電法で得られた直径が４ｎｍの単層カーボンナノチューブを用いたこと以外は実施例４と同様に正極を作製し、その正極を用いた以外は実施例４と同様に円筒形の電気化学キャパシタを作製した。この電気化学キャパシタにおける正極の電気容量は８０ｍＡｈ／ｇであり、正極合剤層の形成量は５ｍｇ／ｃｍ² であって、負極と正極との容量比は負極／正極＝２であった。
【０１０４】
上記のように作製した電気化学キャパシタを、３０ｍＡの定電流で充電カット電圧３．５Ｖ、放電カット電圧１．０Ｖとして充放電させたところ、４０ｍＡｈの放電容量が得られた。上記と同じ充放電条件で１００００サイクルまで充放電を繰り返し、１００００サイクル目の放電容量を測定した。その結果を後記の表２に示す。
【０１０５】
また、上記の電気化学キャパシタを用いた以外は、実施例４と同様にハイブリッド電源を作製し、そのハイブリッド電源の放電容量を実施例４と同様に測定し、かつ初期の放電容量に対して６０％の容量になるまでのサイクル数を実施例４と同様に調べた。その結果を後記の表３に示す。
【０１０６】
比較例４
負極における負極合剤層の形成量を０．４ｍｇ／ｃｍ² とし、負極と正極の容量比を負極／正極＝０．５とした以外は、実施例４と同様に電気化学キャパシタを作製し、その電気化学キャパシタを実施例４と同様に充放電させて放電容量を測定し、かつ１００００サイクル目の放電容量を実施例４と同様に測定した。その結果を後記の表２に示す。
【０１０７】
また、上記の電気化学キャパシタを用いた以外は、実施例４と同様にハイブリッド電源を作製し、そのハイブリッド電源の放電容量を実施例４と同様に測定し、かつ初期の放電容量に対して６０％の容量になるまでのサイクル数を実施例４と同様に調べた。その結果を後記の表３に示す。
【０１０８】
比較例５
負極における負極合剤層の形成量を６．８ｍｇ／ｃｍ² とし、負極と正極の容量比を負極／正極＝７．５とした以外は、実施例４と同様に電気化学キャパシタを作製し、その電気化学キャパシタを実施例４と同様に充放電させて放電容量を測定し、かつ１００００サイクル目の放電容量を実施例４と同様に測定した。その結果を表２に示す。
【０１０９】
また、上記の電気化学キャパシタを用いた以外は、実施例４と同様にハイブリッド電源を作製し、そのハイブリッド電源の放電容量を実施例４と同様に測定し、かつ初期の放電容量に対して６０％の容量になるまでのサイクル数を実施例４と同様に調べた。その結果を表３に示す。
【０１１０】
【表２】

【０１１１】
【表３】

【０１１２】
表３に示すように、実施例４〜５のハイブリッド電源は、比較例４〜５のハイブリッド電源に比べて、放電容量が大きく、高容量で、かつサイクル数が多く、サイクル特性が優れていて、長期間の使用に耐え得ることを示していた。これは、表２に示すように、実施例４〜５のハイブリッド電源に用いた電気化学キャパシタが、比較例４〜５のハイブリッド電源に用いた電気化学キャパシタより、高容量で、かつサイクル特性が優れていることに基づくものである。
【０１１３】
実施例６
実施例４で用いた負極合剤含有ペーストをアルミニウム箔の片面に塗布した以外は実施例４と同様に負極を作製し、かつ実施例４で用いた正極合剤含有ペーストをアルミニウム箔の片面に塗布した以外は実施例４と同様に正極を作製した。
【０１１４】
得られた負極および正極をそれぞれ幅２０ｍｍ、長さ４０ｍｍに切り出し、それらの電極の端にアルミニウム製のタブを溶接した。
【０１１５】
上記負極と正極との間に厚さ２５μｍのポリエチレン不織布からなるセパレータを介在させて、アルミニウム箔を芯材とするラミネートフィルムからなる外装材に装填した。アルゴンガス雰囲気のドライボックス内で、実施例１で用いた電解液を上記ラミネートフィルムからなる外装材内に真空注入し、ヒートシーラーで溶着してラミネート型電気化学キャパシタを作製した。得られた電気化学キャパシタは幅３０ｍｍ、長さ４５ｍｍ、厚さ１ｍｍであった。この電気化学キャパシタを１０ｍＡの定電流で充電電圧３．５Ｖ、放電電圧１．０Ｖとして充放電させたところ、２ｍＡｈの放電容量が得られた。この電気化学キャパシタの許容充電電圧Ｖ_E は３．５Ｖであった。
【０１１６】
つぎに、この電気化学キャパシタを用いて図１に示す構造のハイブリッド電源を作製した。すなわち、上記電気化学キャパシタ５と、２本の単三形アルカリ電池６をポリカーボネート製のパック１（幅３２ｍｍ、長さ５０ｍｍ、厚さ１７ｍｍ）に装填した。なお、２本の電池は直列接続であり２直列である電池の最大電圧Ｖ_B （開回路電圧）は３．２５Ｖであった。
【０１１７】
上記のように作製したハイブリッド電源に外部電気負荷を接続してパルス放電を行った。パルス放電モードは３００ｍＡの電流を２０秒間流した後、１．５Ａのパルス電流を２秒間流した。これを１サイクルとしてハイブリッド電源の電圧が２．０Ｖとなるまでサイクルを繰り返した。ハイブリッド電源は２３℃の恒温槽内に設置し、電圧が２．０Ｖに達するまでのサイクル数を調べた。その結果を表４に示す。
【０１１８】
上記のパルス放電試験が終了したハイブリッド電源中の電池は２本ともパックから取り出すことができ、新しい電池との交換が可能であった。
【０１１９】
比較例６
電気化学キャパシタは装填せず、２直列の単３形アルカリ電池のみを図１のパックに収めたものを電源として実施例６と同様の条件でパルス放電を行い、電圧が２．０Ｖに達するまでのサイクル数を調べた。その結果を表４に示す。
【０１２０】
比較例７
実施例４で正極として作製した活性炭電極を両極とし、それらを実施例６と同様のアルミニウムラミネートフィルムからなる外装材内に装填した。プロピレンカーボネートとジエチルカーボネートとを１：２（体積比）で混合した混合溶媒に（Ｃ₂ Ｈ₅ ）₄ ＮＢＦ₄ を１．５モル／リットルの濃度になるように溶解させた電解液を前記ラミネートフィルムからなる外装材内に真空注入し、封止してラミネート型電気二重層キャパシタ（幅３０ｍｍ、長さ４５ｍｍ、厚さ１ｍｍ）を作製した。この電気二重層キャパシタを１０ｍＡの定電流で充電電圧２．５Ｖ、放電電圧１．０Ｖとして充放電させたところ、０．５ｍＡｈの放電容量が得られた。この電気二重層キャパシタの許容充電電圧Ｖ_E は２．５Ｖであた。
【０１２１】
このラミネート型電気二重層キャパシタと、実施例４と同様に２直列の単三形アルカリ電池から構成される最大電圧Ｖ_B が３．２５Ｖの電池集合体とを並列に接続して図１と同様の構造のハイブリッド電源を作製した。ただし、電池の最大電圧Ｖ_B が電気二重層キャパシタの許容充電電圧Ｖ_E より高いため保護回路を付属させて電気二重層キャパシタが過充電にならないように措置を施した。このハイブリッド電源では、保護回路が必要となったため、パックの大きさは幅３２ｍｍ、長さ５０ｍｍ、厚さ２０ｍｍと、実施例４の場合より厚さが厚くなってしまった。このハイブリッド電源について、実施例４と同様にパルス放電を行い、パルスのサイクル数を調べた。その結果を表４に示す。
【０１２２】
【表４】

【０１２３】
表４に示すように、実施例６のハイブリッド電源は、比較例６の電池単体に比べて、サイクル数が多かった。これは、比較例６の電池単体では、上記パルス放電試験で１．５Ａの電流を流した際、電池の電圧が急激に低下するが、実施例６のハイブリッド電源では、分極による電圧降下を大幅に抑制することができるので、パルスのサイクル数が増えたものと考えられる。
【０１２４】
また、実施例６のハイブリッド電源は、電気二重層キャパシタを用いた比較例７のハイブリッド電源に比べても、サイクル数が多かった。このサイクル数が多いということは、その電源の使用時間をより長くできることを意味しており、特に実施例６のハイブリッド電源は、その構成にあたって用いた電気化学キャパシタが比較例７のハイブリッド電源の構成にあたって用いた電気二重層キャパシタより容量が大きく、高容量であることから、サイクル数が多いことと併せて、非常に有用なものであると言える。
【０１２５】
【発明の効果】
以上説明したように、本発明によれば、高容量で、かつサイクル特性が優れた電気化学キャパシタを提供することができる。また、本発明によれば、小型でかつ過充電になる危険性が少なく、しかも高容量で、かつサイクル特性が優れていて長期間の使用に耐え得るハイブリッド電源を提供することができる。
【図面の簡単な説明】
【図１】本発明に係るハイブリッド電源の外観を示す図である。
【図２】本発明に係るハイブリッド電源の電気化学キャパシタと電池集合体との配置を示す図であって、図１の内面図に相当するものである。
【図３】本発明に係るハイブリッド電源の電気化学キャパシタと電池集合体との接続状態を示す図である。
【符号の説明】
１ パック
２ キャパシタ収納部
３ 電池収納部
４ 電池収納蓋
５ 電気化学キャパシタ
６ 電池
７ 電池コネクター
８ 外部端子
９ 正極端子
１０ 負極端子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrochemical capacitor and a hybrid power source including the electrochemical capacitor, and more particularly, to an organic electrolyte-based electrochemical having both an electrostatic double layer capacitance and a redox capacity using lithium ions as an active material medium. The present invention relates to a capacitor and a hybrid power source using the electrochemical capacitor and a battery together.
[0002]
[Prior art]
The electric double layer capacitor is obtained by increasing the capacity of a conventional capacitor using an electric double layer generated at the interface between the electrode and the electrolyte as an energy source. Accordingly, energy can be taken in and out by rapid charge and discharge, and no oxidation-reduction reaction occurs, so that there is an advantage that cycle deterioration hardly occurs.
[0003]
However, since the electric double layer capacitor does not cause a redox reaction, it cannot achieve a high energy density like a secondary battery, whereas the energy density of a lithium ion battery is 100 Wh / kg or more, whereas the electric double layer capacitor The present energy density is only about 1-2 Wh / kg.
[0004]
Therefore, in place of the conventional electric double layer capacitor having only the capacitance due to the electric double layer, an electrochemical capacitor having a pseudo capacitance due to redox in addition to the capacitance due to the electric double layer capacitor has been proposed. . This electrochemical capacitor uses a redox reaction in the vicinity of the electrode interface, that is, a two-dimensional redox reaction, and is originally distinguished from a battery using a bulk phase (three-dimensional) redox reaction. Is.
[0005]
As an electrode material of this electrochemical capacitor, examples using metal oxides and conductive polymers are well known, and noble metals such as Ru and Ir, and transition metals have been studied as metal oxides. Among these metal oxides, instead of expensive noble metals, as a transition metal-based electrochemical capacitor which has been particularly actively studied in recent years, Telcordia, Inc. uses activated carbon for the positive electrode and spinel type for the negative electrode. A hybrid type electrochemical capacitor using lithium titanium oxide has been reported (see, for example, Non-Patent Document 1).
[0006]
[Non-Patent Document 1]
"An Asymmetry Hybrid Nonaqueous
Energy Storage Cell “Glenn G. Amato”
cci, Journal of the electrochemica
l society, 148 (8) A930-A939 (2001)
[0007]
The electrochemical capacitor having such a configuration has an energy density of several tens of Wh / kg, which is inferior to a lithium ion secondary battery exhibiting an energy density of 100 Wh / kg or more, but more than a capacitor (<1 Wh / kg). It has a high energy density.
[0008]
Even if the present inventors use spinel-type lithium titanium oxide having an average particle diameter of about 1.0 μm prepared by a relatively easy and inexpensive method, the load characteristics are the same as or higher than those of Non-Patent Document 1. As a result, it was confirmed that the cycle characteristics were not as good as reported.
[0009]
Therefore, the appearance of an electrochemical capacitor having a high capacity and excellent cycle characteristics is desired.
[0010]
In recent years, the demand for mobile devices such as mobile phones, personal computers, digital cameras, and video cameras has been increasing year by year. Since these mobile devices are portable devices, a battery is used as a power source.
[0011]
In this mobile device, when turning on the power or pressing the shutter button with the camera, a large current flows instantaneously, and at that time, the battery voltage rapidly decreases. When the voltage drops to a specific battery voltage, the primary battery is replaced and the secondary battery is recharged.
[0012]
However, there are many cases in which the capacity of approximately 50% of the battery to be replaced or charged remains. This is because the voltage drop at the time of high load is large, and the battery must be replaced or recharged while having a remaining capacity at a low current.
[0013]
Therefore, a system in which an electric double layer capacitor having good load characteristics is used in combination with a battery has been proposed in order to cope with an instantaneous high load fluctuation. This electric double layer capacitor uses a cation or an anion in the electrolyte solution adsorbed and desorbed on the surface of a polarizable electrode such as activated carbon, and uses the electric capacitance generated by the electric double layer as an energy source. Since no electrochemical redox reaction occurs, a large current can flow instantaneously. Therefore, if this electric double layer capacitor is connected in parallel to the battery, polarization due to load fluctuation can be suppressed.
[0014]
For example, J. et al. Miller et al. Can suppress a voltage drop at high loads by using a system in which a battery and an electric double layer capacitor are connected in parallel as a power source for the mobile device, and extend the usage time of the battery by five times. It is reported that it can be performed (for example, refer nonpatent literature 2).
[0015]
[Non-Patent Document 2]
5th Intl. Seminar on Double-Layer
Capacitors and Similar Energy St
orage Devices, S.M. P. Wolsky and N.W. M
aricic, eds. Florida Educational
Seminars, BocaRation, Fla. (1995), p
. 3 and 7
[0016]
However, the electric double layer capacitor cannot achieve a high energy density like a secondary battery because no oxidation-reduction reaction occurs, and the energy density of a lithium ion battery is 100 Wh / kg or more, whereas At present, the energy density of the multilayer capacitor is limited to about 1-2 Wh / kg.
[0017]
Therefore, in place of the conventional electric double layer capacitor having only the electrostatic capacitance due to the electric double layer, in addition to the electrostatic capacitance due to the electric double layer capacitor as described in Non-Patent Document 1, a pseudo capacitance due to redox It is conceivable to use an electrochemical capacitor with a battery in combination with a battery.
[0018]
An electrochemical capacitor having such a structure has an energy density of several tens of Wh / kg, which is inferior to a lithium ion secondary battery exhibiting an energy density of 100 Wh / kg or more, but is a capacitor (<1 Wh / kg). As described above, the cycle characteristics are not always good, although the energy density is higher than that of the electric double layer capacitor (<2 Wh / kg).
[0019]
By the way, as a system using both a battery and a capacitor, for example, a system in which three electric double layer capacitors are connected to a two-series lithium ion battery has been proposed (see Patent Document 1).
[0020]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-218381 (first page)
[0021]
In the combined battery / capacitor system described in Patent Document 1, the voltage of a fully charged lithium ion battery is usually about 4.2 V in a single cell, so the voltage in a series of 8.4 V is 8.4 V, and an organic electrolyte is used. Since the maximum voltage of the electric double layer capacitor is usually 2.5V, it becomes 7.5V in three series. That is, since the total maximum voltage of the battery exceeds that of the electric double layer capacitor, if the battery and the electric double layer capacitor are directly connected in parallel, the electric double layer capacitor becomes overcharged and the internal pressure due to the decomposition of the electrolyte Increase in temperature or fever will occur. Therefore, the combined system described in Patent Document 1 has a problem that the protection circuit is incorporated to prevent overcharging of the electric double layer capacitor, and the cost is increased accordingly.
[0022]
In addition, a system in which an electric double layer capacitor is connected to a lithium ion polymer battery and the protection circuit is simplified has been proposed (for example, see Patent Document 2).
[0023]
[Patent Document 2]
JP 2000-013915 A (first page)
[0024]
However, the combined system described in Patent Document 2 has a problem in terms of space because a plurality of electric double layer capacitors are connected for the purpose of adjusting the voltage so that the electric double layer capacitor is not overcharged. This is an obstacle to miniaturization.
[0025]
In addition, the use of natural energy is strongly demanded from the viewpoint of environmental problems, and in particular, the use of solar cells using solar energy is being actively promoted. For example, a system for storing energy generated by a solar battery in a battery has been proposed (see, for example, Patent Document 3).
[0026]
[Patent Document 3]
JP-A-6-351174 (first page)
[0027]
However, since storage batteries are unsuitable for rapid charging and have problems such as being unable to withstand long-term use, an element that stores electric power generated by a solar cell in an electric double layer capacitor is used instead of a storage battery. It has been proposed (see, for example, Patent Document 4).
[0028]
[Patent Document 4]
Japanese Unexamined Patent Publication No. 7-177683 (first page)
[0029]
However, although the electric double layer capacitor has advantages such as long life and high-speed charging, the amount of stored electricity is significantly lower than that of the battery, so there is a problem that the usage time is shortened and the application is limited. there were.
[0030]
As a usage example of a system in which a solar cell and an electric double layer capacitor as described above are used in combination, a power source for roadsides has been proposed (see Patent Document 5).
[0031]
[Patent Document 5]
JP-A-8-232216 (first page)
[0032]
In the combined system described in Patent Document 5, electric power generated by a solar cell during the day is stored in an electric double layer capacitor, and at night, electric power is supplied from the electric double layer capacitor to cause a light emitting diode to blink. Since the roadway usually requires durability of 5 to 7 years or more, a highly durable one such as an electric double layer capacitor is suitable as a storage power source.
[0033]
However, the operating voltage of the electric double layer capacitor is usually in the range of 0 to 2.5V, but the output voltage of the solar cell and the operating voltage of the light emitting diode in the roadside application are often 2.8 to 3.3V. Therefore, since it exceeds the operating voltage of the electric double layer capacitor, a circuit for preventing the electric double layer capacitor from being overcharged, a circuit for boosting, etc. are usually required. Since a capacitor has a very small storage capacity compared to a storage battery, usually, a plurality of electric double layer capacitors had to be connected in parallel. That is, a photovoltaic power generation system combining a solar cell and a conventional electric double layer capacitor has a difficulty in miniaturization and weight reduction because a complex circuit and many electric double layer capacitors must be mounted.
[0034]
[Problems to be solved by the invention]
The first object of the present invention is to solve the problems of the electrochemical capacitor as described above, to provide an electrochemical capacitor having a high capacity and excellent cycle characteristics, and the conventional hybrid as described above. A second object of the present invention is to provide a hybrid power supply that solves the problems of power supplies, is small in size, has a low risk of overcharging, has high capacity, has excellent cycle characteristics, and can withstand long-term use. And
[0035]
[Means for Solving the Problems]
As a result of various studies to solve the above-mentioned problems, the present inventors firstly made a positive electrode using a carbonaceous material capable of adsorbing and desorbing anions, a negative electrode, and an organic electrolytic solution containing a lithium salt as an electrolyte. In the electrochemical capacitor having the above structure, a high capacity is obtained by using lithium titanium oxide having a ramsdellite type crystal structure for the negative electrode and setting the negative electrode / positive electrode capacity ratio to negative electrode / positive electrode = 1-7. In addition, the present inventors have found that an electrochemical capacitor having excellent cycle characteristics can be obtained and the first object can be achieved.
[0036]
Further, the present inventors have said electrochemical capacitor, that is, a positive electrode using a carbonaceous material capable of adsorbing and desorbing anions, a negative electrode using a lithium-containing titanium oxide having a ramsdellite type crystal structure, By connecting in parallel an electrochemical capacitor having a negative electrode / positive electrode capacity ratio of negative electrode / positive electrode = 1 to 7 and an organic electrolyte containing lithium salt as an electrolyte, and a battery in parallel, the size is reduced. In addition, the present inventors have found that a hybrid power source that has a low risk of overcharging, has a high capacity, has excellent cycle characteristics, and can withstand long-term use can be achieved, and the second object can be achieved.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
First, in the present invention, the electrochemical capacitor that can achieve the first object will be described in detail. The electrochemical capacitor of the present invention is an electrostatic capacitance due to an electric double layer at the interface between an electrode and an organic electrolyte. And a redox capacity by an electrochemical oxidation-reduction reaction in a single element, which is a hybrid type electrochemical capacitor having a positive electrode made of a carbonaceous material capable of adsorbing and desorbing anions A negative electrode using lithium titanium oxide having a ramsdellite-type crystal structure capable of electrochemical insertion and desorption of lithium ions, and an organic electrolyte containing a lithium salt as an electrolyte. And the capacity ratio of the positive electrode is negative electrode / positive electrode = 1-7.
[0038]
In the electrochemical capacitor of the present invention, lithium titanium oxide used for the negative electrode has a ramsdellite type crystal structure, and belongs to the chemical formula Li₂Ti_ThreeO₇, Li_FourTi_FiveO₁₂In particular, the chemical formula Li₂Ti_ThreeO₇The thing represented by these is preferable. And this Li₂Ti_ThreeO₇In this case, it is preferable that the d value of the main peak by the X-ray diffraction method using Cu as a target is 0.445 nm, 0.269 nm, 0.224 nm, and 0.177 nm (each ± 0.0002 nm).
[0039]
The lithium titanium oxide having the ramsdellite type crystal structure has a reduction potential of Li / Li.⁺On the other hand, it starts from around 2.0 V and proceeds with a gentle potential gradient to around 0.5 V, and in the oxidation reaction, the potential rises slightly and proceeds in the opposite direction. In contrast, even if the same lithium titanium oxide, the chemical formula Li_FourTi_FiveO₁₂Lithium titanium oxide having a spinel type crystal structure represented by⁺On the other hand, it has a very flat charge / discharge curve around 1.5V.
[0040]
When charging and discharging are performed using lithium titanium oxide for the negative electrode and activated carbon as the carbonaceous material for the positive electrode, adsorption and desorption of the anion of the lithium salt used as the electrolyte occurs in the positive electrode, and lithium ion is used in the negative electrode. Intercalation occurs. At this time, when a lithium titanium oxide having a ramsdellite-type crystal structure is used for the negative electrode, the Li (lithium) potential at the time of charging is higher than when a lithium titanium oxide having a spinel-type crystal structure is used. On the other hand, since the potential difference between the positive and negative electrodes is small, it is considered that the adsorption of anions proceeds more easily and an electrochemical capacitor having characteristics suitable for a long cycle life can be obtained.
[0041]
The lithium titanium oxide having the ramsdellite type crystal structure can be used regardless of the production method thereof, for example, one selected from lithium hydroxide, lithium oxide, lithium nitrate, lithium carbonate, or the like, or A step of mixing a plurality of lithium compounds and titanium oxide, followed by heat treatment at a temperature from 1000 ° C. to about 1400 ° C. close to the temperature at which the lithium titanium oxide melts, and then grinding with an alumina ball mill or the like It can manufacture by the solid-phase method which goes through. In this case, the lithium titanium oxide preferably has an average particle diameter of 10 μm or less, particularly preferably an average particle diameter of 0.01 μm or more, and particularly preferably 0.01 to 1 μm. That is, when the average particle diameter of the lithium titanium oxide is 10 μm or less, it is possible to suppress a decrease in output characteristics due to a delay in diffusion of lithium ions into the particles due to excessively large particles, When the average particle diameter is 0.01 μm or more, it is possible to suppress a decrease in dispersibility due to aggregation of particles during electrode production and a decrease in workability associated therewith.
[0042]
In addition, the lithium titanium oxide having the ramsdellite type crystal structure is synthesized by hydrolytic reaction, dehydration condensation reaction, and heat treatment using an organometallic compound as a starting material, except in the case of the solid phase method. You may manufacture by the sol-gel method which goes through the process to do. According to the sol-gel method, the heat treatment temperature can be made lower than in the case of the solid phase method, which is advantageous in terms of cost.
[0043]
In order to produce a negative electrode using the lithium titanium oxide having the ramsdelite type crystal structure obtained as described above, for example, a lithium oxide having the ramsdelite type crystal structure is added to a conductive auxiliary agent. A binder such as polytetrafluoroethylene or polyvinylidene fluoride may be added and mixed, and the obtained negative electrode mixture may be formed by an appropriate means. For example, the negative electrode mixture is pressure-molded, or the negative electrode mixture is dispersed in a solvent to prepare a negative electrode mixture-containing paste (in this case, the binder is previously dissolved or dispersed in the solvent). (It may be mixed with lithium titanium oxide, etc.), and the obtained negative electrode mixture-containing paste is applied to a current collector made of metal foil or metal net and dried to form a film-like negative electrode mixture layer And a negative electrode is producible by passing through the process compressed as needed. However, the method for manufacturing the negative electrode is not limited to the above-described method, and other methods may be used.
[0044]
The conductive auxiliary agent is not particularly limited in terms of material and shape, but substantially carbonaceous materials are preferably used. Specific examples thereof include, for example, carbon black, acetylene black, Examples include regular carbon, carbon fiber, natural graphite, and artificial graphite.
[0045]
Any mixing means such as a stirrer, ball mill, ultrasonic dispersion, etc. can be employed for mixing and dispersing the lithium titanium oxide having the ramsdellite type crystal structure, and a conductive additive or binder. Although there are no particular limitations regarding the temperature and time of the hour, for example, it is preferable to mix and disperse at 0 to 40 ° C. for about 1 to 12 hours. The mixing ratio of the lithium titanium oxide having the ramsdellite type crystal structure, the conductive assistant and the binder is preferably 80: 15: 5 to 50:30:20, and particularly 70:20:10 to 60 in terms of mass ratio. : 25: 15 is preferred.
[0046]
In the present invention, the positive electrode is PF.₆ ^-And BF_Four ^-For example, activated carbon or single-walled carbon nanotubes are preferable as the carbonaceous material. When these carbonaceous materials are charged and discharged in an electrochemical cell, the electrochemical redox reaction of doping and dedoping the anionic species into the carbon layer does not occur, and only the anions are adsorbed and desorbed into the carbon layer. So rapid anion transfer can be achieved. Further, these carbonaceous materials have a linear charge / discharge potential change as described above, and do not show a flat portion of the potential or a shoulder with a gentle slope unlike materials used for battery active materials.
[0047]
Moreover, as said activated carbon, the specific surface area by BET specific surface area measurement is 1000 m.²/ G or more is preferable. This is because the specific surface area of the carbonaceous material measured by BET specific surface area is 1000 m.²This is because, by being at least / g, it is possible to suppress a decrease in capacitance due to the electric double layer generated at the interface between the carbonaceous material and the organic electrolyte.
[0048]
Further, the activated carbon has micropores with a diameter of less than 2 nm, mesopores with a diameter in the range of 2 to 50 nm, and macropores with a diameter of more than 50 nm, and the pore volume of the micropores is 0.5 cc / g or more, the pore volume of the mesopores is 0.3 cc / g or more, the abundance ratio of the micropore pore volume to the total pore volume is 50 to 75%, and the pore volume of the mesopores The abundance ratio is preferably 25 to 50%. Further, the ratio of the pore volume of the macropores to the total pore volume is preferably 3% or less, particularly preferably 1% or less, and particularly preferably close to 0%. And as this activated carbon, that whose average particle diameter is 5-20 micrometers is preferable.
[0049]
The pores are defined by IUPAC as micropores having a diameter smaller than 2 nm, mesopores having a diameter of 2 to 50 nm, and macropores having a diameter larger than 50 nm, but usually a large number of ions are present in the mesopores. It is said that adsorption and desorption is performed, and a high mesopore volume is considered preferable as the activated carbon for capacitor electrodes.
[0050]
However, PF adsorbs and desorbs on activated carbon.₆ ^-And BF_Four ^-Since the size of the anion such as is usually 1 nm or less, the anion can sufficiently move even within the pores of the micropores and should be able to be adsorbed. Therefore, the present inventors have fully developed micropores, specifically, the pore volume of micropores measured by a method using a mercury porosimeter is 0.5 cc / g or more, and mesopores have also developed. Specifically, the pore volume of the mesopore is 0.3 cc / g or more, and the ratio of the pore volume of the micropore to the total pore volume is 50 to 75%. It has been found that when activated carbon having an abundance ratio of 25 to 50% is used, a high capacitance can be obtained by adsorption and desorption of anions. This is thought to be because the development of mesopores larger in diameter than the micropores promotes the movement of anions and increases the amount of adsorption / desorption to the micropores.
[0051]
In addition, the particle diameter of the activated carbon is preferably 5 to 20 μm in terms of an average particle diameter for reasons such as shortening the moving distance of ions and ensuring a large specific surface area. If the average particle diameter of the activated carbon is larger than 20 μm, the particle diameter is too large and ions may not be able to move rapidly to the inside of the particle. There is a risk that the holes cannot be sufficiently developed.
[0052]
The activated carbon is not particularly limited with respect to the raw material and the production method, and usually starts with coconut husk, petroleum coke, phenolic resin, etc., preferably starting with phenolic resin and carbonized at about 600 to 800 ° C. Alternatively, it can be obtained by an activation treatment with an alkaline aqueous solution, preferably an alkaline aqueous solution.
[0053]
In order to produce a positive electrode using the carbonaceous material, for example, the same conductive additive and binder as in the case of the negative electrode are added to and mixed with the carbonaceous material, and the obtained positive electrode mixture is mixed with appropriate means. It can be formed with. For example, the positive electrode mixture is pressure-molded, or the positive electrode mixture is dispersed in a solvent to prepare a positive electrode mixture-containing paste (in this case, the binder is previously dissolved or dispersed in the solvent). The obtained positive electrode mixture-containing paste may be applied to a current collector made of a metal foil or a metal net, and dried to form a film-like positive electrode mixture layer. The positive electrode can be produced by going through a step of compressing as necessary. However, the method for manufacturing the positive electrode is not limited to the above-described method, and other methods may be used.
[0054]
And in producing an electrochemical capacitor, the capacity ratio of a negative electrode and a positive electrode needs to be made into negative electrode / positive electrode = 1-7, and negative electrode / positive electrode = 1.5-5 is preferable. That is, if the capacity ratio is less than 1 or greater than 7, sufficient capacity and cycle characteristics cannot be obtained. Here, the capacity of the negative electrode and the positive electrode is, for example, a three-electrode type or two-electrode type electrochemical cell with metallic lithium as a counter electrode, and the capacity per electrode mass obtained and each electrode filled in the electrochemical capacitor. You can know from the mass of. However, the mass of the electrode means the mass of the electrode mixture and does not include the mass of the current collector.
[0055]
In constructing the electrochemical capacitor of the present invention, an organic electrolyte prepared by dissolving an electrolyte in an organic solvent is used. The solvent of the organic electrolyte solution is not particularly limited. For example, cyclic esters such as ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, ethylene glycol sulfite, dimethyl carbonate, diethyl carbonate and the like. The chain esters can be used alone or in combination of two or more. As an electrolyte, for example, LiClO_Four, LiPF₆, LiBF_Four, LiAsF₆, LiSbF₆, LiCF_ThreeSO_Three, LiCF_ThreeCO₂, Li₂C₂F_Four(SO_Three)₂, LiN (CF_ThreeSO₂)₂, LiC (CF_ThreeSO₂)_Three, LiC_nF_{2n + 1}SO_ThreeLithium salts such as (n ≧ 2) can be used alone or in combination of two or more. The concentration of the electrolyte in the electrolytic solution is not particularly limited, but is preferably about 0.3 to 2 mol / l, particularly about 0.4 to 1.5 mol / l.
[0056]
In addition, the electrochemical capacitor of the present invention is not particularly limited in terms of shape, such as a cylindrical shape, a square shape, or a coin shape, and the manufacturing method thereof is not particularly limited. For example, when producing a cylindrical electrochemical capacitor, a negative electrode and a positive electrode formed into a sheet shape are wound into a roll shape through a separator similar to that used for a battery or a capacitor. A body is prepared, the wound body is filled into a bottomed cylindrical can, the organic electrolyte is injected, and then sealed.
[0057]
The electrochemical capacitor of the present invention has a redox capacity due to the function of doping / dedoping lithium ions into the lithium titanium oxide of the negative electrode, in addition to the interface between the carbonaceous material of the positive electrode and the organic electrolyte. In addition, it has a capacitance due to the electric double layer generated at the same time, so to speak, it is an element having both characteristics of a lithium ion battery and an electric double layer capacitor. Therefore, the electrochemical capacitor of the present invention is particularly suitable for a power source of a device that requires an instantaneous large current and an energy capacity, and a power source of a device that requires a long charge / discharge cycle life.
[0058]
Next, a hybrid power supply that achieves the second object in the present invention will be described. The hybrid power supply of the present invention is configured by connecting the electrochemical capacitor and the battery in parallel. At this time, the electrochemical capacitor of the present invention has an allowable charging voltage V_EIs a high allowable charging voltage V of 2.5 to 3.5V_ETherefore, the electrochemical capacitor is less likely to be overcharged under normal conditions, thus preventing overcharge as occurs when using a conventional electric double layer capacitor. There is no need to provide a protective circuit for connecting two or more electric double layer capacitors in series, and the high capacity and excellent cycle characteristics of an electrochemical capacitor are also maintained in a hybrid power supply. You can save it. Therefore, the use of the electrochemical capacitor of the present invention provides a hybrid power supply that is small in size and has a low risk of being overcharged, has high capacity, has excellent cycle characteristics, and can withstand long-term use. be able to.
[0059]
In the hybrid power source of the present invention, as described above, the electrochemical capacitor includes a positive electrode using a carbonaceous material capable of adsorbing and desorbing anions, and a negative electrode using a lithium-containing titanium oxide having a ramsdellite type crystal structure. And an organic electrolytic solution containing a lithium salt as an electrolyte, and an electric capacity ratio of the negative electrode to the positive electrode is negative electrode / positive electrode = 1-7, in parallel with the electrochemical capacitor As a battery to be connected, a commonly used primary battery or secondary battery can be used, and a solar battery can also be used.
[0060]
Examples of the primary battery include a manganese battery, an alkaline battery, a nickel battery, and a lithium battery. Alkaline batteries and nickel batteries that are widely used in digital cameras and the like are usually used in two series, and therefore, a withstand voltage of 3.2 to 3.4 V is usually required for elements connected in parallel. As described above, since the operating voltage range of the electric double layer capacitor is 0 to 2.5 V, in order to connect these batteries and one electric double layer capacitor in parallel, a circuit for preventing overcharging is provided, Although it is necessary to take measures such as connecting two or more double layer capacitors in series, the electrochemical capacitor used in the hybrid power source of the present invention exhibits a permissible charging voltage of 3.5 V at the maximum. No complicated charging prevention circuit is required.
[0061]
Examples of the secondary battery connected in parallel with the electrochemical capacitor include a lead battery, a nickel cadmium battery, and a nickel metal hydride battery. These batteries may be used in two or more series, in which case the maximum voltage of the batteries may exceed 3V. In this case, if these batteries and one electric double layer capacitor having a withstand voltage of 2.5V are connected in parallel, the electric double layer capacitor is overcharged. Therefore, it is necessary to provide a protection circuit or to connect two or more electric double layer capacitors in series. However, the electrochemical capacitor used in the hybrid power source of the present invention has a high withstand voltage, so only one capacitor is sufficient. A protection circuit is also unnecessary.
[0062]
The solar cell connected in parallel with the electrochemical capacitor is not particularly limited with respect to its configuration and output, and an amorphous solar cell, a crystalline silicon solar cell, a dye-sensitized solar cell, or the like is preferably used. The number of modules is not particularly limited, and may be appropriately selected according to the use of devices to be operated.
[0063]
The hybrid power source according to the present invention has an allowable charging voltage V of the electrochemical capacitor._EIs 2.5 to 3.5 V, and the maximum voltage V of the battery_BIs 2.5 to 3.5V, and V_E≧ V_BSatisfied. Where V_BMeans the maximum voltage exhibited by the battery during open or closed circuit.
[0064]
Allowable charging voltage V of the electrochemical capacitor_EIs adjusted by the type of the negative electrode active material, the capacity ratio between the positive electrode and the negative electrode, or the capacity utilization of the electrochemical capacitor. Allowable charging voltage V in the present invention_EWhen an electrochemical capacitor is installed in a cylindrical can, etc., the maximum charging voltage that does not cause abnormal appearance of the electrochemical control such as capacity and cycle is observed, and there is no abnormality in the appearance such as blistering or heat generation of the can. means.
[0065]
Allowable charging voltage V_EWhen lithium-containing titanium oxide is used as the negative electrode active material, there are problems such as structural breakdown of the negative electrode active material if the negative electrode side is less than 1 V with respect to the Li potential, and the oxidation resistance voltage on the positive electrode side is low. For example, 3.5V is the maximum value because it is about 4.5V with respect to the lithium potential.
[0066]
V_E≧ V_BIs not satisfied, that is, V_BIs V_EWhen a higher voltage is exhibited, it is not preferable to directly connect the battery and the electrochemical capacitor in parallel because the electrochemical capacitor is overcharged, and in some cases, the electrochemical capacitor is damaged.
[0067]
Therefore, in the present invention, when the hybrid capacitor is configured by connecting the electrochemical capacitor and the battery in parallel, the allowable charging voltage V_EThe electrochemical capacitor of the present invention having a voltage of 2.5 to 3.5 V and the maximum voltage V_BIs connected in parallel with one series or more parallel batteries with 2.5 to 3.5V, and V_E≧ V_BIf satisfied, it is possible to provide a small and lightweight hybrid power source that does not require a complicated protection circuit.
[0068]
Here, a structural example of the hybrid power source of the present invention will be described with reference to FIGS. FIG. 1 shows the appearance of a hybrid power source in which an electrochemical capacitor and a battery are loaded in a pack 1 made of a plastic exterior material. The pack 1 has a capacitor housing part 2 for loading an electrochemical capacitor, a battery housing part 3 for loading a battery, and a battery housing lid 4 for taking in and out the battery. FIG. 2 shows the contents of the hybrid power source shown in FIG. 1. A laminate-type electrochemical capacitor 5 is built in the back of the pack, and two cylindrical batteries 6 are connected to each other via a battery connector 7. They are connected in series or in parallel. An external terminal 8 for electrically connecting to an external load is provided on the bottom of the pack. FIG. 3 shows a connection state of the electrochemical capacitor 5 and the two series batteries 6. The electrochemical capacitor 5 and the battery 6 are connected in parallel through the positive electrode terminal 9 and the negative electrode terminal 10 in the pack. . Since the battery 6 can be inserted into and removed from the pack 1, when the capacity of the battery is exhausted, the primary battery can be replaced with a new battery, and the secondary battery can be replaced with a dedicated charger. What is necessary is just to use the battery pack again after recharging. In the case of a secondary battery, the entire pack can be recharged with a charger.
[0069]
Although FIGS. 1-3 showed the example using the laminate type electrochemical capacitor and the cylindrical battery, these may be a square shape, a gum shape, etc., and there is no restriction | limiting regarding the shape. Further, the number of batteries may be four in two series and two in parallel.
[0070]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. However, this invention is not limited only to those Examples. In addition, in the following examples etc.,% which shows the density | concentrations of a solution, a dispersion liquid, etc. is the mass% unless it mentions the reference | standard especially, Examples 1-3 and Comparative Examples 1-3 are related with an electrochemical capacitor. Examples 4 to 6 and Comparative Examples 4 to 7 relate to a hybrid power source.
[0071]
Example 1
Chemical formula Li₂Ti_ThreeO₇The average particle diameter by particle size distribution measurement using a laser diffraction / scattering method is 0.47 μm, and the specific surface area by nitrogen adsorption determined by the BET 5-point method is 7.5 m.²A negative electrode was prepared in the following procedure using lithium titanium oxide having a ramsdellite type crystal structure of / g.
[0072]
First, a binder liquid in which 10 parts by mass of polyvinylidene fluoride as a binder was dissolved in 23 parts by mass of an N-methyl-2-pyrrolidone solvent was prepared, and acetylene black and ketjen black as conductive assistants were added to the binder liquid. 25 parts by mass of the mixture was added and pre-dispersed with a stirrer for 5 hours in advance. The liquid containing the conductive assistant and the binder and 65 parts by mass of the lithium titanium oxide were mixed and dispersed with an ultrasonic homogenizer having an output of 150 W to prepare a negative electrode mixture-containing paste.
[0073]
After applying the obtained negative electrode mixture-containing paste onto an aluminum foil having a thickness of 40 μm with a clearance of 60 μm with an applicator and pre-drying it on a hot plate at 100 ° C. for 20 minutes to form a negative electrode mixture layer, the back surface Was applied with an applicator at a clearance of 100 μm and pre-dried on a hot plate at 100 ° C. for 20 minutes to form a negative electrode mixture layer. Furthermore, after vacuum-drying at 80 ° C. for 12 hours, the obtained electrode body was 1 ton / cm.²After pressing for 10 seconds at 3 ton / cm²Was pressed for 10 seconds to obtain a negative electrode.
[0074]
The thickness of the obtained negative electrode was 70 μm, and the amount of the negative electrode mixture layer formed (however, the amount of the negative electrode mixture layer formed per unit square centimeter; hereinafter the same) was 2.5 mg / cm on both sides.²Met. This has an area of 2cm on one side²The working electrode was used as the working electrode, metallic lithium was used for the counter electrode and the reference electrode, and 1.5 M LiPF was used as the electrolyte.₆/ EC + DEC [LiPF in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC)₆Electrolyte solution prepared by dissolving 1.5 mol / l] in a three-electrode electrochemical cell with a charge / discharge voltage of 1 to 2.5 V and a current density of 0.5 mA / cm.²The capacity per unit mass of the negative electrode when the capacity was measured was 90 mAh / g. However, the mass of the negative electrode in the above means the mass of the negative electrode mixture, and does not include the mass of the aluminum foil that is the current collector.
[0075]
The negative electrode after pressing is cut into a width of 24 mm and a length of 186 mm, and is used as a negative electrode for forming an electrochemical capacitor. As a positive electrode material to be combined with the negative electrode, a specific surface area according to a 5-point method of BET specific surface area measurement is 1200 m.²A positive electrode was produced as shown below using activated carbon of / g. First, polyvinylidene fluoride was dissolved in 23 parts by mass of N-methyl-2-pyrrolidone so as to have a concentration of 25%, and 15 parts by mass of acetylene black as a conductive assistant was added to the solution and dispersed with a stirrer for 5 hours. The liquid containing the conductive assistant and the binder and 60 parts by mass of the activated carbon were mixed and dispersed with an ultrasonic homogenizer with an output of 150 W to prepare a positive electrode mixture-containing paste. The obtained positive electrode mixture-containing paste was applied on an aluminum foil having a thickness of 40 μm with a clearance of 140 μm with an applicator and pre-dried on a hot plate at 100 ° C. for 20 minutes to form a positive electrode mixture layer. The back surface was coated with an applicator with a clearance of 220 μm and pre-dried on a hot plate at 100 ° C. for 20 minutes to form a positive electrode mixture layer. The obtained electrode body is 1 ton / cm.²After pressing for 10 seconds at 3 ton / cm²Was pressed for 10 seconds to a thickness of 0.13 mm, and then cut into a width of 24 mm and a length of 171 mm to form a positive electrode. The thickness of the positive electrode is 0.13 mm as described above, and the formation amount of the positive electrode mixture layer (however, the formation amount of the positive electrode mixture layer is also the formation of the positive electrode mixture layer per unit square centimeter). (The same applies hereinafter) is 2.5 mg / cm on both sides.²Met.
[0076]
The positive electrode and the negative electrode prepared as described above were vacuum-dried at 120 ° C. for 3 days, and then wound in a dry atmosphere through two separators made of a microporous polyethylene film having a thickness of 25 μm and a width of 27 mm, A wound body of less than 10 mm was produced.
[0077]
After attaching a rubber cap to the wound body and drying at 80 ° C. for 12 hours, the composition is 1.5 M LiPF in an inert atmosphere.₆/ EC + DEC organic electrolyte [ie, LiPF in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC)₆Was dissolved in 1.5 mol / l of an organic electrolyte solution], and vacuum-opening was repeated three times to impregnate the wound body with the organic electrolyte solution. Thus, the amount of the organic electrolyte solution impregnated in the wound body was 1.2 g.
[0078]
The wound body impregnated with the organic electrolyte solution was placed in a bottomed cylindrical can having an outer diameter of 10 mm and a height of 40 mm, and sealed according to a conventional method to obtain an electrochemical capacitor. The capacity ratio of the negative electrode to the positive electrode of the cylindrical electrochemical capacitor thus prepared was negative electrode / positive electrode = 3.0. And after charging this electrochemical capacitor to 3.1V with a constant current of 14.4 mA, the charge / discharge cycle which discharges to 1.0V was repeated 3 times, and the chemical conversion treatment was performed.
[0079]
Example 2
The amount of the negative electrode mixture layer formed in the negative electrode is 1.3 mg / cm²Then, an electrochemical capacitor was prepared and subjected to chemical conversion treatment in the same manner as in Example 1 except that the capacity ratio of the negative electrode to the positive electrode was changed to negative electrode / positive electrode = 1.5.
[0080]
Example 3
The amount of the negative electrode mixture layer formed in the negative electrode is 4.5 mg / cm²Then, an electrochemical capacitor was prepared and subjected to chemical conversion treatment in the same manner as in Example 1 except that the capacity ratio of the negative electrode to the positive electrode was changed to negative electrode / positive electrode = 5.0.
[0081]
Comparative Example 1
The amount of the negative electrode mixture layer formed in the negative electrode is 0.4 mg / cm²Then, an electrochemical capacitor was prepared and subjected to chemical conversion treatment in the same manner as in Example 1 except that the capacity ratio of the negative electrode to the positive electrode was changed to negative electrode / positive electrode = 0.5.
[0082]
Comparative Example 2
The formation amount of the negative electrode mixture layer in the negative electrode is 6.8 mg / cm²Then, an electrochemical capacitor was prepared and subjected to chemical conversion treatment in the same manner as in Example 1 except that the capacity ratio of the negative electrode to the positive electrode was changed to negative electrode / positive electrode = 7.5.
[0083]
Comparative Example 3
Instead of the ramsdellite-type lithium titanium oxide used in Example 1, the diffraction pattern by the X-ray diffraction method is represented by the chemical formula Li_FourTi_FiveO₁₂An electrochemical capacitor was prepared and subjected to a chemical conversion treatment in the same manner as in Example 1 except that lithium titanium oxide having a spinel crystal structure belonging to 1 was used.
[0084]
The cycle characteristics of the electrochemical capacitors of Examples 1 to 3 and Comparative Examples 1 to 3 after the chemical conversion treatment were evaluated. That is, the electrochemical capacitors of Examples 1 to 3 and Comparative Examples 1 to 3 after the chemical conversion treatment were repeatedly charged and discharged at a constant current of 72 mA under the conditions of a charge cut voltage of 3.1 V and a discharge cut voltage of 1.0 V. The cycle characteristics were evaluated. The cycle test is performed at 25 ° C., and the discharge capacity at the first cycle and the discharge capacity at the 10000th cycle are measured. From these, the capacity of the discharge capacity at the 10000th cycle relative to the discharge capacity at the 1st cycle is calculated from Retention was determined.
[0085]

[0086]
The capacity retention obtained as described above is shown in Table 1 together with the capacity ratio between the negative electrode and the positive electrode, the crystal structure of the lithium titanium oxide of the negative electrode, and the discharge capacity at the first cycle.
[0087]
[Table 1]

[0088]
As shown in Table 1, the electrochemical capacitors of Examples 1 to 3 have a larger discharge capacity at the first cycle and a larger capacity retention rate at the 10000th cycle than the electrochemical capacitors of Comparative Examples 1 to 3. , High capacity and excellent cycle characteristics. That is, the electrochemical capacitors of Examples 1 to 3 using lithium titanium oxide having a ramsdellite type crystal structure for the negative electrode and having a negative electrode / positive electrode capacity ratio in the range of negative electrode / positive electrode = 1 to 7 Although the capacity and the cycle characteristics were excellent, even when lithium titanium oxide having the same crystal structure was used, the capacity ratio of the negative electrode to the positive electrode was outside the range of negative electrode / positive electrode = 1-7. The electrochemical capacitor had a smaller capacity and inferior cycle characteristics than the electrochemical capacitors of Examples 1 to 3.
[0089]
In addition, the electrochemical capacitor of Comparative Example 3 using the same lithium titanium oxide having a spinel crystal structure as the negative electrode has a capacity close to that of the electrochemical capacitors of Examples 1 to 3. However, the cycle characteristics were significantly inferior to the electrochemical capacitors of Examples 1 to 3. In other words, even when the same lithium titanium oxide is used, when lithium titanium oxide having a ramsdellite type crystal structure is used for the negative electrode, when lithium titanium oxide having a spinel type crystal structure is used for the negative electrode, In comparison, it was clear that an electrochemical capacitor having significantly improved cycle characteristics was obtained.
[0090]
As described above, according to the present invention, an electrochemical capacitor having a high capacity and excellent cycle characteristics can be provided.
[0091]
Next, Examples 4 to 6 and Comparative Examples 4 to 7 relating to the hybrid power source will be described.
[0092]
Example 4
Chemical formula Li₂Ti_ThreeO₇The average particle diameter by particle size distribution measurement using a laser diffraction / scattering method is 0.6 μm, and the d value of the main peak by an X-ray diffraction method using Cu as a target is 0.445 nm, 0.269 nm, A dispersion aqueous solution containing 3 parts by mass of acetylene black and 70% polytetrafluoroethylene was added to 60 parts by mass of lithium titanium oxide having a thickness of 0.224 nm and 0.177 nm so that polytetrafluoroethylene was 10 parts by mass. The negative electrode mixture-containing paste thus obtained was applied to both sides of an aluminum foil having a thickness of 15 μm and a width of 200 mm, and dried at 120 ° C. to form a negative electrode mixture layer, followed by 3 ton / cm.²And a negative electrode was produced.
[0093]
The thickness of the obtained negative electrode was 70 μm, and the amount of the negative electrode mixture layer formed (however, the amount of the negative electrode mixture layer formed per unit square centimeter, hereinafter the same) was 7.8 mg / cm on both sides.²Met. This has an area of 2cm on one side²The working electrode was used as the working electrode, the counter electrode and the reference electrode were made of lithium metal, and the organic electrolyte was 1.5 M LiPF.₆/ EC + DEC [LiPF in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC)₆Organic electrolyte solution prepared by dissolving 1.5 mol / l] in a three-electrode electrochemical cell with a charge / discharge voltage of 1 to 2.5 V and a current density of 0.5 mA / cm²The capacity per unit mass of the negative electrode when the capacity was measured was 100 mAh / g. However, the mass of the negative electrode in the above means the mass of the negative electrode mixture, and does not include the mass of the aluminum foil that is the current collector.
[0094]
For the positive electrode, an activated carbon having an average particle diameter of 15 μm obtained by carbonizing a phenol resin and activating in a potassium hydroxide aqueous solution was used. This activated carbon has a BET specific surface area of 3200 m by nitrogen adsorption.²/ G, the pore volume of the micropores is 1.0 cc / g, the pore volume of the mesopores is 0.7 cc / g, and the ratio of the pore volume of the micropores to the total pore volume is 60 %, The abundance ratio of mesopore volume to total pore volume was 39%.
[0095]
A positive electrode obtained by adding 5 parts by mass of acetylene black to 90 parts by mass of the activated carbon and kneading a dispersion aqueous solution containing 70% polytetrafluoroethylene so that the amount of polytetrafluoroethylene is 5 parts by mass. The mixture-containing paste was applied to both sides of an aluminum foil having a thickness of 15 μm, dried at 120 ° C. to form a positive electrode mixture layer, and then 3 ton / cm.²Was pressed to prepare a positive electrode.
[0096]
The thickness of the obtained positive electrode was 90 μm, and the amount of the positive electrode mixture layer formed was 2.0 mg / cm on both sides.²Met. This has an area of 2cm on one side²The capacity was measured with a three-electrode electrochemical cell as in the case of the negative electrode. Charge cut voltage is 4.5V, discharge cut voltage is 3V, current density is 0.5mA / cm²The capacity per unit mass of the positive electrode was 80 mAh / g. However, the mass of the positive electrode in the above means the mass of the positive electrode mixture, and does not include the mass of the aluminum foil as the current collector.
[0097]
The negative electrode was cut to a width of 40 mm and a length of 320 mm, the positive electrode was cut to a width of 40 mm and a length of 310 mm, and an aluminum tab was welded to the center of each to make a negative electrode and a positive electrode for electrochemical capacitor construction.
[0098]
The negative electrode and the positive electrode were wound through a separator made of a microporous polyethylene film having a thickness of 25 μm to obtain a wound body having a diameter of 9.5 mm and a length of 40 mm. This wound body was loaded into a cylindrical can having a diameter of 10 mm and a height of 45 mm. In a dry box in an argon gas atmosphere, LiPF was mixed with a mixed solvent in which propylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 2.₆Was poured into the cylindrical can, and the open portion of the cylindrical can was closed with a 5 mm thick sealing body made of butyl rubber and caulked into a cylinder. A shaped electrochemical capacitor was fabricated. The capacity ratio of the negative electrode to the positive electrode in this cylindrical electrochemical capacitor was negative electrode / positive electrode = 5.
[0099]
The electrochemical capacitor produced as described above was charged and discharged at a constant current of 30 mA under the conditions of a charge cut voltage of 3.5 V and a discharge cut voltage of 1.0 V, and the initial discharge capacity was measured. As a result, a discharge capacity of 45 mAh was obtained. Obtained. Charging / discharging was repeated up to 10,000 cycles under the same charging / discharging conditions as above, and the discharge capacity at the 10,000th cycle was measured. The results are shown in Table 2 below.
[0100]
Next, the cylindrical electrochemical capacitor produced as described above is connected to a crystalline silicon solar cell module (output 0.22 W, voltage 3.3 V, size 50 × 55 mm) in which six cells are connected in series. A hybrid power source was fabricated by connecting in parallel via electric wires.
[0101]
The solar cell of the hybrid power source manufactured as described above was irradiated for 1 hour at 80 ° C. under illumination with an illuminance of 50,000 lux. Thereafter, the solar cell was covered with a black cloth so as to prevent further power generation, an external power source was connected, 10 mA constant current discharge was performed, the discharge cut voltage was set to 1 V, and the discharge capacity was measured. The obtained discharge capacity is shown in Table 3 below.
[0102]
The above operation was repeated until the capacity reached 60% of the initial discharge capacity, and the number of cycles that could be repeated was examined. The results are shown in Table 3 below.
[0103]
Example 5
A positive electrode was produced in the same manner as in Example 4 except that single-walled carbon nanotubes having a diameter of 4 nm obtained by the arc discharge method were used instead of the activated carbon, and a cylinder was obtained in the same manner as in Example 4 except that the positive electrode was used. A shaped electrochemical capacitor was fabricated. The electric capacity of the positive electrode in this electrochemical capacitor is 80 mAh / g, and the amount of the positive electrode mixture layer formed is 5 mg / cm.²The capacity ratio between the negative electrode and the positive electrode was negative electrode / positive electrode = 2.
[0104]
When the electrochemical capacitor produced as described above was charged and discharged with a constant current of 30 mA and a charge cut voltage of 3.5 V and a discharge cut voltage of 1.0 V, a discharge capacity of 40 mAh was obtained. Charge / discharge was repeated up to 10,000 cycles under the same charge / discharge conditions as above, and the discharge capacity at the 10,000th cycle was measured. The results are shown in Table 2 below.
[0105]
Further, a hybrid power source was produced in the same manner as in Example 4 except that the above-described electrochemical capacitor was used, the discharge capacity of the hybrid power source was measured in the same manner as in Example 4, and 60% of the initial discharge capacity was measured. The number of cycles until the capacity reached% was examined in the same manner as in Example 4. The results are shown in Table 3 below.
[0106]
Comparative Example 4
The amount of the negative electrode mixture layer formed in the negative electrode is 0.4 mg / cm²The electrochemical capacitor was prepared in the same manner as in Example 4 except that the negative electrode / positive electrode capacity ratio was set to negative electrode / positive electrode = 0.5, and the electrochemical capacitor was charged and discharged in the same manner as in Example 4 to discharge. The capacity was measured, and the discharge capacity at the 10,000th cycle was measured in the same manner as in Example 4. The results are shown in Table 2 below.
[0107]
Further, a hybrid power source was produced in the same manner as in Example 4 except that the above-described electrochemical capacitor was used, the discharge capacity of the hybrid power source was measured in the same manner as in Example 4, and 60% of the initial discharge capacity was measured. The number of cycles until the capacity reached% was examined in the same manner as in Example 4. The results are shown in Table 3 below.
[0108]
Comparative Example 5
The formation amount of the negative electrode mixture layer in the negative electrode is 6.8 mg / cm²The electrochemical capacitor was prepared in the same manner as in Example 4 except that the negative electrode / positive electrode capacity ratio was set to negative electrode / positive electrode = 7.5, and the electrochemical capacitor was charged and discharged in the same manner as in Example 4 to discharge. The capacity was measured, and the discharge capacity at the 10,000th cycle was measured in the same manner as in Example 4. The results are shown in Table 2.
[0109]
Further, a hybrid power source was produced in the same manner as in Example 4 except that the above-described electrochemical capacitor was used, the discharge capacity of the hybrid power source was measured in the same manner as in Example 4, and 60% of the initial discharge capacity was measured. The number of cycles until the capacity reached% was examined in the same manner as in Example 4. The results are shown in Table 3.
[0110]
[Table 2]

[0111]
[Table 3]

[0112]
As shown in Table 3, the hybrid power sources of Examples 4 to 5 have a large discharge capacity, a high capacity, a large number of cycles, and excellent cycle characteristics as compared with the hybrid power sources of Comparative Examples 4 to 5. Has shown that it can withstand long-term use. As shown in Table 2, the electrochemical capacitors used in the hybrid power sources of Examples 4 to 5 have higher capacity and cycle characteristics than the electrochemical capacitors used for the hybrid power sources of Comparative Examples 4 to 5. It is based on being superior.
[0113]
Example 6
A negative electrode was prepared in the same manner as in Example 4 except that the negative electrode mixture-containing paste used in Example 4 was applied to one side of the aluminum foil, and the positive electrode mixture-containing paste used in Example 4 was applied to one side of the aluminum foil. A positive electrode was produced in the same manner as in Example 4 except that the coating was performed.
[0114]
The obtained negative electrode and positive electrode were cut into a width of 20 mm and a length of 40 mm, respectively, and aluminum tabs were welded to the ends of the electrodes.
[0115]
A separator made of a polyethylene nonwoven fabric having a thickness of 25 μm was interposed between the negative electrode and the positive electrode, and loaded into an exterior material made of a laminate film having an aluminum foil as a core material. In a dry box in an argon gas atmosphere, the electrolyte solution used in Example 1 was vacuum-injected into the outer packaging material made of the laminate film and welded with a heat sealer to produce a laminated electrochemical capacitor. The obtained electrochemical capacitor had a width of 30 mm, a length of 45 mm, and a thickness of 1 mm. When this electrochemical capacitor was charged and discharged at a constant current of 10 mA at a charging voltage of 3.5 V and a discharging voltage of 1.0 V, a discharge capacity of 2 mAh was obtained. Allowable charging voltage V of this electrochemical capacitor_EWas 3.5V.
[0116]
Next, a hybrid power source having the structure shown in FIG. 1 was produced using this electrochemical capacitor. That is, the electrochemical capacitor 5 and the two AA alkaline batteries 6 were loaded into a pack 1 made of polycarbonate (width 32 mm, length 50 mm, thickness 17 mm). Note that the two batteries are connected in series, and the maximum voltage V of the two batteries in series._BThe (open circuit voltage) was 3.25V.
[0117]
Pulse discharge was performed by connecting an external electric load to the hybrid power source manufactured as described above. In the pulse discharge mode, a 300 mA current was passed for 20 seconds, and then a 1.5 A pulse current was passed for 2 seconds. This was taken as one cycle, and the cycle was repeated until the voltage of the hybrid power supply reached 2.0V. The hybrid power supply was installed in a thermostat at 23 ° C., and the number of cycles until the voltage reached 2.0 V was examined. The results are shown in Table 4.
[0118]
Both of the batteries in the hybrid power source for which the above pulse discharge test was completed could be taken out of the pack and replaced with new batteries.
[0119]
Comparative Example 6
Electrochemical capacitors were not loaded, and pulse discharge was performed under the same conditions as in Example 6 using only two AA alkaline batteries in series in the pack of FIG. 1 as the power source until the voltage reached 2.0V. The number of cycles was examined. The results are shown in Table 4.
[0120]
Comparative Example 7
The activated carbon electrode produced as a positive electrode in Example 4 was used as both electrodes, and they were loaded in an exterior material made of the same aluminum laminate film as in Example 6. To a mixed solvent in which propylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 2 (C₂H_Five)_FourNBF_FourWas dissolved in the outer packaging material made of the laminate film and sealed to form a laminated electric double layer capacitor (width 30 mm, length 45 mm, A thickness of 1 mm) was produced. When this electric double layer capacitor was charged and discharged at a constant current of 10 mA at a charge voltage of 2.5 V and a discharge voltage of 1.0 V, a discharge capacity of 0.5 mAh was obtained. Allowable charging voltage V of this electric double layer capacitor_EWas 2.5V.
[0121]
The maximum voltage V composed of this laminate type electric double layer capacitor and two series AA alkaline batteries as in Example 4._BWas connected in parallel to a 3.25V battery assembly to produce a hybrid power supply having the same structure as in FIG. However, the maximum battery voltage V_BIs the allowable charging voltage V of the electric double layer capacitor_ESince it is higher, a protection circuit is attached to prevent the electric double layer capacitor from being overcharged. Since this hybrid power supply requires a protection circuit, the pack has a width of 32 mm, a length of 50 mm, and a thickness of 20 mm, which is thicker than in the case of Example 4. With respect to this hybrid power source, pulse discharge was performed in the same manner as in Example 4, and the number of pulse cycles was examined. The results are shown in Table 4.
[0122]
[Table 4]

[0123]
As shown in Table 4, the hybrid power source of Example 6 had a larger number of cycles than the battery unit of Comparative Example 6. This is because the battery voltage of the battery of Comparative Example 6 suddenly drops when a current of 1.5 A is passed in the pulse discharge test, but the hybrid power supply of Example 6 greatly reduces the voltage drop due to polarization. It is considered that the number of pulse cycles has increased.
[0124]
Moreover, the number of cycles of the hybrid power source of Example 6 was larger than that of the hybrid power source of Comparative Example 7 using an electric double layer capacitor. The large number of cycles means that the use time of the power source can be made longer. In particular, the hybrid power source of Example 6 has the electrochemical capacitor used in the configuration of the hybrid power source of Comparative Example 7 Since it has a larger capacity and higher capacity than the electric double layer capacitor used in the above, it can be said that it is very useful in combination with a large number of cycles.
[0125]
【The invention's effect】
As described above, according to the present invention, an electrochemical capacitor having a high capacity and excellent cycle characteristics can be provided. Further, according to the present invention, it is possible to provide a hybrid power source that is small in size and has a low risk of overcharging, has a high capacity, has excellent cycle characteristics, and can withstand long-term use.
[Brief description of the drawings]
FIG. 1 is a diagram showing an appearance of a hybrid power source according to the present invention.
FIG. 2 is a view showing an arrangement of an electrochemical capacitor and a battery assembly of a hybrid power source according to the present invention and corresponds to the inner view of FIG.
FIG. 3 is a diagram showing a connection state between an electrochemical capacitor and a battery assembly of a hybrid power source according to the present invention.
[Explanation of symbols]
1 pack
2 Capacitor storage
3 Battery compartment
4 Battery compartment cover
5 Electrochemical capacitors
6 batteries
7 Battery connector
8 External terminal
9 Positive terminal
10 Negative terminal

Claims (6)

A positive electrode adsorption and desorption of anions using a carbonaceous material capable, a negative electrode, an electrochemical capacitor to organic electrolyte components containing lithium salt as the electrolyte, the chemical formula Li ₂ to the negative electrode Ti ₃ O ₇ An electrochemical capacitor using lithium titanium oxide having a ramsdellite type crystal structure represented by the formula: wherein the negative electrode / positive electrode has an electric capacity ratio of negative electrode / positive electrode = 1-7. The carbonaceous material used for the positive electrode has micropores with a diameter of less than 2 nm, mesopores with a diameter in the range of 2 to 50 nm, and macropores with a diameter of more than 50 nm. 5 cc / g or more, the pore volume of the mesopores is 0.3 cc / g or more, and the ratio of the pore volume of the micropores to the total pore volume is 50 to 75%, and the total pore volume abundance ratio of the pore volume of mesopores is a 25 to 50% of an average particle size of activated carbon 5~20μm claim 1 Symbol placement of the electrochemical capacitor. A positive electrode using a carbonaceous material capable of adsorbing and desorbing anions, and a chemical formula Li ₂ Ti ₃ O ₇ In a negative electrode employing a lithium titanium oxide having a crystal structure of ramsdellite represented, as a component of the organic electrolyte containing lithium salt as an electrolyte, the electric capacity ratio of the negative electrode and the positive electrode is a negative electrode / A hybrid power source comprising an electrochemical capacitor having a positive electrode = 1 to 7 and a battery connected in parallel. A positive electrode using a carbonaceous material capable of adsorbing and desorbing anions, and a chemical formula Li ₂ Ti ₃ O ₇ In a negative electrode employing a lithium titanium oxide having a crystal structure of ramsdellite represented, as a component of the organic electrolyte containing lithium salt as an electrolyte, the electric capacity ratio of the negative electrode and the positive electrode is a negative electrode / The hybrid power supply according to claim 3 , wherein the battery connected in parallel with the electrochemical capacitor having the positive electrode = 1 to 7 is a solar battery. The carbonaceous material using the positive electrode has micropores having a diameter of less than 2 nm, mesopores having a diameter in the range of 2 to 50 nm, and macropores having a diameter of more than 50 nm. 5 cc / g or more, the pore volume of the mesopores is 0.3 cc / g or more, and the ratio of the pore volume of the micropores to the total pore volume is 50 to 75%, and the total pore volume 5. The hybrid power source according to claim 3 , wherein the hybrid power source is activated carbon having an abundance ratio of mesopore volume to 25 to 50% and an average particle diameter of 5 to 20 μm. A positive electrode using a carbonaceous material capable of adsorbing and desorbing anions, and a chemical formula Li ₂ Ti ₃ O ₇ In a negative electrode employing a lithium titanium oxide having a crystal structure of ramsdellite represented, as a component of the organic electrolyte containing lithium salt as an electrolyte, the electric capacity ratio of the negative electrode and the positive electrode is a negative electrode / a positive electrode = 1-7, an electrochemical capacitor permissible charging voltage _{V E} is 2.5～3.5V, capable of mounting and detaching the maximum voltage _{V B} is in the range of 2.5～3.5V A hybrid power supply comprising a battery and the same pack, wherein V _E ≧ V _B is satisfied.

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