JP3844103B2

JP3844103B2 - Grooved electrode material for liquid flow type electrolytic cell and method for producing the same

Info

Publication number: JP3844103B2
Application number: JP16223898A
Authority: JP
Inventors: 誠井上; 真申小林
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 1998-06-10
Filing date: 1998-06-10
Publication date: 2006-11-08
Anticipated expiration: 2018-06-10
Also published as: JPH11354131A

Description

【０００１】
【発明の属する技術分野】
本発明は電極材、特にレドックスフロー型電池に用いられる液流通型電解槽に使用される溝付き電極材に関するものである。
【０００２】
【従来技術】
近年、クリーンな電気エネルギーの需要が急速に伸び、それに伴って電解槽を利用する分野が増えつつある。その代表的なものとして、一次・二次・燃料電池といった各種電池及び電気メッキ、食塩電解、有機化合物の電解合成などの電解工業がある。これらの電解槽に用いられる電極には、鉛蓄電池などの電池に多くみられるような電極自体が活物質として電気化学的反応を行うものと、活物質の電気化学的反応を進行させる反応場として働き、電極自身は変化しないものとがある。後者の電極は主に新型二次電池や電解工業に適用されている。
【０００３】
新型二次電池の中でも、レドックスフロー型電池があげられるがこの電池は、電解液を貯える外部タンクと電解槽から成り、活物質を含む電解液を外部タンクから電解槽に供給して電解槽に組み込まれた電極上で電気化学的なエネルギー変換、即ち充放電が行われる。一般に、充放電の際は、電解液を外部タンクと電解槽との間で循環させるため、電解槽は図１に示すような液流通型構造をとる。該液流通型電解槽を単セルと称し、これを最小単位として単独もしくは多段積層して用いられる。液流通型電解槽における電気化学反応は、電極表面で起こる不均一相反応であるため、一般的には二次元的な電解反応場を伴うことになる。電解反応場が二次元的であると、電解槽の単位体積当たりの反応量が小さいという難点がある。そこで、単位面積当たりの反応量、すなわち電流密度を増すために電気化学反応場の三次元化が行われるようになった。図２は、三次元電極を有する液流通型電解槽の模式図である。
【０００４】
該電解槽では、相対する２枚の集電板１があり、１間にイオン交換膜３が配設され、イオン交換膜３の両側のスペーサ２によって集電板１に沿った電解液の流路４ａ，４ｂが形成されている。該流通路４ａ，４ｂの少なくとも一方には炭素繊維集合体等の多孔質電極材５が配設されており、このようにして三次元電極が構成されている。
【０００５】
このような電極材を有する三次元電極からなる液流通型電解槽では、充放電を行う際に液体状の反応活物質を電解槽に供給するために送液ポンプが用いられるがポンプの作動に必要なエネルギーは少ない程よく、ポンプ動力効率のよいポンプが用いられる。しかし液体状の反応活物質を電解槽に供給する場合は通液圧力損失が不可避に生じる。ここで通液圧力損失が生じると所定の流量を確保するためにポンプの送液量を上げる必要があり、ポンプ稼動のためのエネルギー消費量が増加する。この場合、とくにレドックスフロー電池のような充放電可能な二次電池においては電池自体の総合エネルギー効率は充放電の電力効率から送液に必要なエネルギーをロス分として差し引いたものとなり、電力効率が良くてもポンプ動力が大きくてはエネルギーの損失が大きく電池としての総合エネルギー効率が低下する。従って電解槽による通液圧損は低い程よい。
【０００６】
電解槽の通液圧損は三次元電極の多孔質電極材によるものとそれ以外（電解槽の配管部、マニホールドなど）による。ここで三次元電極を有する多孔質電極材が同一密度の場合、該三次元電極を形成する多孔質電極材の厚みを増加させスペーサーの厚みを増加すれば電解液の流速を低減することによって通液圧力損失を低下させることができ、ポンプの負荷を低減する事が出来る。しかしながら三次元電極の厚みを増加させることは電極材の使用量を増加させることになり、電池のトータルコストを高めるという新たな問題を生じる。
【０００７】
この問題を解決するために特開昭６３−２００４６７号公報には５番手以上の太い糸とこれを交差する方向にこれよりも細い糸から構成される編織物の炭素質電極材が提案されているがこの電極材では電極材を構成する太糸およびまたは細い糸が脱落したり目づれをおこし、また所定の大きさに切断する時に形状が安定せず精度よく切断できない等ハンドリングの悪さの問題が発生した。そこで本発明者は特開平０８−２８７９２３号公報で所定の寸法の溝を有する炭素質不織布を発明した。しかしながらこの発明では電極材でイオン交換膜を挟み対なる集電板で圧接して電解層を構成する際に圧接の圧力で溝が減少し期待どうりの通液圧損が得られないという問題が生じた。
【０００８】
【発明が解決しようとする課題】
本発明はかかる事情に鑑みなされたものであり、電解層構成時における圧接の圧力で生じる溝の減少を抑制し電極材の基本的な性能を損なうことなく液流通時の通液圧力損失を抑制する電極材を提供することを目的とするものである。
【０００９】
本発明者らは、上記課題を解決することを目的として、電極材の溝の圧縮保持率に着目し鋭意検討した結果、溝を構成する表面のポイント圧縮保持率に対する溝を構成しない裏面のポイント圧縮保持率の比が一定値以下の場合には、電極材の基本的な性能を損なうことなく液流通時の通液圧力損失を抑制することが可能となることを見出した。
【００１０】
また、本発明者らは、上記の溝付き電極材は、有機質バインダーを一定量有する炭化可能な不織布を一定条件下で加熱加圧し溝を形成した後に、炭化することにより得られることを見出した。
【００１１】
本発明者らは、上記の知見に基づいてさらに重ねて検討した結果、本発明を完成したものである。
【００１２】
【課題を解決するための手段】
即ち、本発明は、炭素質繊維を主成分とする不織布からなる溝付き電極材であって、前記不織布の溝を有する面（表面）の土手部分のポイント圧縮保持率（Ａ）と溝のない面（裏面）のポイント圧縮保持率（Ｂ）との比（Ｂ／Ａ）が０．９５以下である液流通型電解槽用溝付き電極材（以下単に溝付き電極材という）を提供するものである。
【００１３】
本発明の溝付き電極材の好ましい実施態様は、前記不織布の目付量が１００ｇ／ｍ²以上であり、且つ、前記不織布の嵩密度が０．０５ｇ／ｃｃ〜０．１５ｇ／ｃｃである。
【００１４】
本発明の溝付き電極材の好ましい実施態様は、前記溝の幅が１ｍｍ〜５ｍｍであり、前記溝の深さが前記不織布の厚みの２０％以上である。
【００１５】
本発明の溝付き電極材の好ましい実施態様は、前記溝を２以上有し、且つ、隣接する溝と溝との間隔が溝の幅より大きいことである。
【００１７】
【発明の実施の形態】
本発明の溝付き電極は、炭素繊維を主成分とする不織布からなる溝付き電極材であることが必要である。主として、液流通型電解槽、つまり電極材が隔膜を介して両極の少なくとも一方に存在し、集電板で圧接して構成される三次元電極、中でもレドックスフロー電池に好適に適用するためである。
【００１８】
即ち、本発明は、炭素質繊維を主成分とする不織布からなる溝付き電極材であって、前記不織布の溝を有する面の土手部分のポイント圧縮率（Ａ）と溝のない面のポイント圧縮率（Ｂ）との比（Ｂ／Ａ）が０．９５以下である溝付き電極材を提供するものである。
本発明の溝付き電極材は、電極を構成する際の溝の減少を低減するために、不織布の溝を有する面（表面）の土手部分のポイント圧縮保持率と溝を有さない面（裏面）の圧縮保持率に差を持たせたもので、不織布の溝を有する面（表面）の土手部分のポイント圧縮保持率（Ａ）と溝のない面（裏面）のポイント圧縮保持率（Ｂ）との比（Ｂ／Ａ）が０．９５以下であることが必要であり、０．９４以下であればより好ましい。０．９５より大きい場合、表面と裏面の圧縮保持率が接近してくるので深い溝を形成しても電極として構成する際に付加される圧力によって、溝が消滅し、通液性が悪化するからである。
【００１９】
本発明において、上記の圧縮保持率は、表面・裏面各々を先端が球状の厚み測定子を用いて荷重４ｇ−ｆから５０ｇ−ｆまでの厚み変化量を測定して算出される。
【００２０】
なお、本発明において、溝とは、不織布断面に凹状態が連続して形成されて流路を形成しているものをいう（図３）。
【００２１】
本発明の溝付き電極材を構成する不織布の目付量は、少なくとも１００ｇ／ｍ²以上が好ましく、１００〜８００ｇ／ｍ²であればより好ましい。目付量が１００ｇ／ｍ²未満の場合には、三次元電極材としての反応場が不足して電解層の内部抵抗が増加する。
【００２２】
本発明の溝付き電極材を構成する不織布の嵩密度は、０．０５〜０．１５ｇ／ｃｃであれば好ましく、０．０６〜０．１４ｇ／ｃｃであればより好ましい。嵩密度が０．０５ｇ／ｃｃ未満である場合には、集電板との接触性が低く電解槽の接触抵抗が増加し、反対に嵩密度が０．１５ｇ／ｃｃを越える場合には、電解液が溝部に集中して流通しやすくなり電極材の内部に均一拡散せず、却って電極材の利用率が低下する。
【００２３】
本発明においては、上記の目付及び密度の範囲を満たし、電極材の厚みが図２のスペーサ２の厚みより大きい方が好ましく、特にスペーサ厚みの１．５〜３倍程度の大きさであればより好ましい。
【００２４】
本発明の溝付き電極材の溝の幅は、１〜５ｍｍであり、且つ、溝の深さは不織布の厚みに対して２０％以上であることが好ましい。溝の幅が１ｍｍ未満である場合、又は、溝の深さが厚みに対して２０％未満である場合には、電解槽作成時に電極材が圧接される際に溝が消滅し、通液圧損が増加する。また、溝の幅が５ｍｍを越える場合には、電極材が圧接される際に溝が消滅する。
【００２５】
本発明の溝付き電極材の溝の間隔は、溝の幅より大きい方が好ましい。溝の間隔が溝の幅より小さい場合には、電極材と集電板の接合性が低下し接触抵抗が増加する。
【００２６】
本発明の溝付き電極材の溝の総断面積は、電解層流路幅と電極材の厚みの積に対して１％以上になるように溝本数を設置することが好ましい。
なお、電極材の溝の総断面積（ＳＭｎ）は、下記の式１により求められる。
電極材の溝の総断面積（ＳＭｎ）＝ｔＭ×ＤＭ×ｎ（式１）
但し、ｔＭ：溝の深さ
ＤＭ：溝の幅
ｎ：溝の数
【００２７】
また、本発明の溝付き不織布において、溝を配設する方向は電解槽中央のイオン交換膜に向かい合うように設置してもよいし、集電板に向かい合うように設置しても良い。しかし溝は電解液の流路と平行に配列される方が好ましい。
【００２８】
本発明の溝付き電極材の製造方法は、有機質バインダーを０．１〜１０重量％含有する炭化可能な不織布を１〜５００ｋｇ／ｃｍ²の圧力で、１００〜２００℃、０．１〜５分間、加熱加圧成型することにより溝を形成した後に、炭化することが必要である。
【００２９】
上記の炭化可能な不織布は、特に限定されるものではなく、例えば、等方性ピッチやメゾフェースピッチのプリカーサ繊維、セルロース繊維、硬化ノボラック繊維、ポリビニルアルコール繊維、芳香族ポリアミド繊維、ポリｐ−フェニレンベンズオキサゾール繊維などがあるが特にポリアクリロニトリル繊維を公知の方法で耐炎化した耐炎化繊維を原料として用いることが好ましい。
【００３０】
上記の炭素化可能な材料を不織布化する方法は、特に限定されるものではないが、例えば、カードによって解繊し、多層化されたウェブをニードルパンチによって不織布化する方法等が好適に用いられる。また溝の形成を容易にするために、異なる繊維素材の不織布を多層積層してもよく、異なる繊維素材を混繊して不織布を作成してもよい。
【００３１】
さらに溝を付与する方法は前記の不織布に所定の山幅、山と山の間隔、高さを既定した金型を上記不織布に載せ、１００〜２００℃の温度で時間０．１〜５分間、圧力１〜５００ｋｇ／ｃｍ²で加熱加圧成型して溝付きの不織布を得る。ここで厚み方向の裏面／表面の圧縮保持率の比率が低い材料にするには不織布化された原料に有機質バインダーを０．１〜１０重量％含有させ溝付けを行うことが好ましい。
【００３２】
なおこれらの溝付け条件・バインダー量が前記の範囲をはずれると厚み方向の裏面／表面の圧縮保持率の比率１に近くなり表面、裏面の圧縮保持率に違いがなくなるため電極構成時に有効な溝が残らず、通液性が悪化する。
【００３３】
上記の圧力はプレス機にかける荷重（＝プレス機のシリンダー断面積×ゲージ圧力）をプレスされる不織布の面積で除した値を採用している。
【００３４】
上記の有機質バインダーは、アクリル系、セルロース系、ポリビニルアルコール系、エポキシ樹脂系、酢酸ビニル系、フェノール樹脂系があるが特に加熱硬化し炭化することで焼成後も安定した溝を形成するフェノール樹脂系が望ましい。バインダーの不織布への含有方法は、表裏の圧縮保持率に差を持たせる為には粉末バインダーを表面散布する場合上面より散布し散布後に下方からサクションで吸引することによりバインダーを不織布内部に固定化する事が望ましい。また、溝の付与の困難な不織布については先に溝を形成した不織布と貼り合わせて一体化してもよい。
【００３５】
こうして得られた溝付きの不織布は導電性付与のため不活性雰囲気下にて８００〜２５００℃で炭素化される。さらに炭素化の後は電解液との濡れ性を向上させるために５００〜１０００℃で空気中にて表面酸化を行い、炭素質電極材を得る。なお炭素化法、酸化法は公知の方法でよいが炭素の結晶面間隔が３．７オングストローム以下でかつＥＳＣＡ表面分析による表面酸素原子数が炭素原子数の少なくとも７％以上になるように製造されることが好ましい。
【００３６】
本発明において採用される電極材の目付、電極材厚み、嵩密度、溝厚み、溝の深さ、溝幅、溝間隔、厚み方向の圧縮保持率の裏面／表面比率および通液圧力損失は以下の要領で測定される。
【００３７】
（１）目付（Ｗ）
通液圧力損失測定に用いるサンプル１０ｃｍ角（寸法：ａ）を１００C 、１時間で乾燥し、デシケータで放冷後電子天秤にて秤量する（重量：ｗ’）。更に以下に示す式によって目付を算出する。
目付Ｗ＝ｗ’／ａ＾２
【００３８】
（２）不織布の厚み（ｔ）
通液圧力損失測定に用いるサンプル１０cm角の四隅と中央部分の５点を、サンプルの土手部分を測定子の中心に合わせ尾崎製作所（株）製デジタルリニアゲージＤ１０（最大荷重１００ｇ−ｆ）に３２ｍｍΦの測定子を用いて測定し、小数点以下２桁まで読み取り平均して最小位を四捨五入する。使用単位をミリメートルとする。
【００３９】
（３）嵩密度
目付を電極材厚みで除して算出する。（単位ｇ／ｃｃ）
【００４０】
（４）溝の厚み（ｔｍ）
通液圧力損失測定に用いるサンプル１０cm角の溝部分の厚み６点を尾崎製作所（株）製ダイヤルシックネスゲージ（型式Ｇ：最大荷重１８０ｇ−ｆ）に接触面寸法１ｍｍ×１０ｍｍで測定し、小数点以下２桁まで読み取り平均し、最小位を四捨五入する。使用単位をミリメートルとする。
【００４１】
（５）溝の深さ（ｔＭ）
（４）の溝厚みの値と（２）の電極材厚みの値との差を溝の深さ（単位：ミリメートル）とする。
【００４２】
（６）溝の幅（ＤＭ）
溝の幅をミツトヨ（株）製デジマティック・キャリパ（シリーズ５００）で測定し、小数点以下２桁まで読み取り、最小位を四捨五入する。
【００４３】
（７）溝の間隔（ＰＭ）
隣在する溝の両端部、即ち土手の部分（図３）をミツトヨ（株）製デジマティック・キャリパ（シリーズ５００）で測定し、小数点以下２桁まで読み取り、最小位を四捨五入する。（単位：ミリメートル）
【００４４】
（８）厚み方向のポイント圧縮保持率の裏面／表面比率
圧縮厚み試験機に測定子（尾崎製作所（株）製球状測定子Ｘ−１）を装着し、寸法２５ｍｍ×１０ｍｍの試験片を用意する。ゼロ荷重時でのゼロ点を調整した後、試験片の表面の土手の部分に測定子を合わせ４ｇ−ｆの荷重をかけそのときの厚みを読みとる（Ｘａ４）。その後５０ｇ−ｆまで圧縮し、この時の厚みを読みとる（Ｘａ５０）。これらのデータから式２−１によって表面のポイント圧縮保持率を得る。
表面のポイント圧縮保持率（Ａ）＝Ｘａ５０／Ｘａ４（式２−１）
さらに先述の測定片を裏返し、土手の部分に相当する部分に測定子を合わせ４ｇ−ｆの荷重をかけそのときの厚みを読みとる（Ｘｂ４）。その後５０ｇ−ｆまで圧縮し、この時の厚みを読みとる（Ｘｂ５０）。これらのデータから式２−２によって裏面のポイント圧縮保持率を得る。
裏面のポイント圧縮保持率（Ｂ）＝Ｘｂ５０／Ｘｂ４（式２−２）
表面と裏面の圧縮保持率の比は式２−３によって得る。

【００４５】
（９）通液圧力損失
図２に示す液流通型電解層と同じ形状で通液方向に２０cm、幅方向（流路幅）１０cm、所定厚みのスペーサー（２）で形成された液流通型電解層を用意し、作成された電極材を１０cm角に切って設置する。液量１０リットル／時のイオン交換水を流通させ、電解槽の出入口の通液圧力損失を測定する。ブランクとして電極材を設置しない系で同様に測定し、測定値とブランク測定値との差を電極材の通液圧力損失とする。
【００４６】
【実施例】
以下に実施例、比較例を挙げて本発明を説明する。
（実施例１）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量９００ｇ／ｍ²、厚み６．１ｍｍの不織布を得た。該不織布上に粉末ノボラック樹脂（昭和高分子（株）製ＢＲＰ５３４Ａ）を１８．９ｇ／ｍ²の割合で均一に散布し、下方より線速３．０ｍ／ｓｅｃのサクションで吸引してバインダーを不織布上に固定化しバインダー含有耐炎化不織布を得た。さらに該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔１３ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。
該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１５００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中７００℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００４７】
（比較例１）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量９００ｇ／ｍ²、厚み６．１ｍｍの不織布を得た。該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔１３ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１５００C まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中７００℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００４８】
（実施例２）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量６００ｇ／ｍ²、厚み４．８ｍｍの不織布を得た。該不織布上に粉末ノボラック樹脂（昭和高分子（株）製ＢＲＰ５３４Ａ）を１８．９ｇ／ｍ²の割合で均一に散布し、下方より線速２．６ｍ／ｓｅｃのサクションで吸引してバインダーを不織布上に固定化しバインダー含有耐炎化不織布を得た。さらに該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔１３ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。
該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１３００Cまで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中６５０℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００４９】
（比較例２）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量６００ｇ／ｍ²、厚み４．８ｍｍの不織布を得た。該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔１３ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１３００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中６５０℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００５０】
（実施例３−１）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量５００ｇ／ｍ²、厚み４．６ｍｍの不織布を得た。該不織布上に粉末ノボラック樹脂（昭和高分子（株）製ＢＲＰ５３４）を１８．９ｇ／ｍ²の割合で均一に散布し、下方より線速２．６ｍ／ｓｅｃのサクションで吸引してバインダーを不織布上に固定化しバインダー含有耐炎化不織布を得た。さらに該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔２３ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。
該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１３００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中６５０℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００５１】
（参考例）平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量５００ｇ／ｍ2 、厚み４．６ｍｍの不織布を得た。該不織布をレゾールエマルジョン（昭和高分子（株）製ＢＲＬ２８５４）０．３重量％水浴中にディップし、ピックアップ率２００％になるようにマングルで絞り１００℃、１時間乾燥してバインダー含有耐炎化不織布を得た。さらに該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔２３ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ2 で１分間プレスして溝付き耐炎化繊維不織布を得た。該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１３００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中６５０℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００５２】
（比較例３）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量５００ｇ／ｍ²、厚み４．８ｍｍの不織布を得た。該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔２３ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１３００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中６５０℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００５３】
（実施例４）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量４５０ｇ／ｍ²、厚み４．５ｍｍの不織布を得た。該不織布上に粉末ノボラック樹脂（昭和高分子（株）製ＢＲＰ５３４Ａ）を１８．９ｇ／ｍ²の割合で均一に散布し、下方より線速２．６ｍ／ｓｅｃのサクションで吸引してバインダーを不織布上に固定化しバインダー含有耐炎化不織布を得た。さらに該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔１３ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。
該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１３００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中６５０℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００５４】
（比較例４）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量４５０ｇ／ｍ²、厚み４．５ｍｍの不織布を得た。該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ，山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔１３ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１３００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中６５０℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００５５】
（実施例５）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量３５０ｇ／ｍ²、厚み４．０ｍｍの不織布を得た。該不織布上に粉末ノボラック樹脂（昭和高分子（株）製ＢＲＰ５３４Ａ）を１８．９ｇ／ｍ²の割合で均一に散布し、下方より線速２．６ｍ／ｓｅｃのサクションで吸引してバインダーを不織布上に固定化しバインダー含有耐炎化不織布を得た。さらに該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔１５ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。
該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１３００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中６５０℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００５６】
（比較例５）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量３５０ｇ／ｍ²、厚み４．０ｍｍの不織布を得た。該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１０ｍｍ、山長さ３００ｍｍ、山と山の間隔１３ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１３００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中６５０℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００５７】
（実施例６）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量８６０ｇ／ｍ²、厚み６．０ｍｍの不織布を得た。該不織布上に粉末ノボラック樹脂（昭和高分子（株）製ＢＲＰ５３４Ａ）を１８．９ｇ／ｍ²の割合で均一に散布し、下方より線速３．０ｍｍ／ｓｅｃのサクションで吸引してバインダーを不織布上に固定化しバインダー含有耐炎化不織布を得た。さらに該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１．５ｍｍ、山長さ３００ｍｍ、山と山の間隔６ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。
該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１５００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中７００℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００５８】
（比較例６）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量８６０ｇ／ｍ²、厚み６．０ｍｍの不織布を得た。該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１．５ｍｍ、山長さ３００ｍｍ、山と山の間隔６ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１５００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中７００℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００５９】
（実施例７）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量９３０ｇ／ｍ²、厚み６．２ｍｍの不織布を得た。該不織布上に粉末ノボラック樹脂（昭和高分子（株）製ＢＲＰ５３４Ａ）を３１．２ｇ／ｍ²の割合で均一に散布し、下方より線速３．０ｍ／ｓｅｃのサクションで吸引してバインダーを不織布上に固定化しバインダー含有耐炎化不織布を得た。さらに該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１．５ｍｍ、山長さ３００ｍｍ、山と山の間隔６ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。
該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１５００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中７００℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００６０】
（比較例７）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量９３０ｇ／ｍ²、厚み６．２ｍｍの不織布を得た。該不織布を３００ｍｍ角にカットしその上に山幅２．０ｍｍ、山高さ１．５ｍｍ、山長さ３００ｍｍ、山と山の間隔６ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１５００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中７００℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００６１】
（実施例８）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量９２０ｇ／ｍ²、厚み６．２ｍｍの不織布を得た。該不織布上に粉末ノボラック樹脂（昭和高分子(株）製ＢＲＰ５３４Ａ）を３１．２ｇ／ｍ²の割合で均一に散布し、下方より線速３．０ｍ／ｓｅｃのサクションで吸引してバインダーを不織布上に固定化しバインダー含有耐炎化不織布を得た。さらに該不織布を３００ｍｍ角にカットしその上に山幅３．０ｍｍ、山高さ１．５ｍｍ、山長さ３００ｍｍ、山と山の間隔６ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。
該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１５００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中７００℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００６２】
（比較例８）
平均繊維直径１６μｍのポリアクリロニトリル（ＰＡＮ）繊維を空気中２５０℃で耐炎化した後、該耐炎化繊維の短繊維を用いてフェルト化して目付量９３０ｇ／ｍ²、厚み６．２ｍｍの不織布を得た。該不織布を３００ｍｍ角にカットしその上に山幅３．０ｍｍ、山高さ１．５ｍｍ、山長さ３００ｍｍ、山と山の間隔６ｍｍの山を有するアルミニウム製の金型３００ｍｍ角を山が不織布に向き合うように重ねて温度１８０℃、シリンダー直径１６０ｍｍのヒートプレス装置にセットし、圧力２０ｋｇ／ｃｍ²で１分間プレスして溝付き耐炎化繊維不織布を得た。該耐炎化繊維不織布を不活性ガス中で１０℃／分の昇温速度で１５００℃まで昇温し、この温度で１時間保持し炭化を行ったのち冷却し炭化物を得た。該炭化物は空気中７００℃で重量収率９３％になるまで酸化処理し、溝付き炭素質繊維不織布を得た。
該溝付き炭素質繊維不織布の目付、厚み、密度、溝の厚み、溝の深さ、溝の幅、溝の間隔、厚み方向のポイント圧縮保持率の裏面／表面比率、通液圧損および通液圧損測定時のスペーサー厚みを表１に示す。
【００６３】
【表１】

【００６４】
【作用】
本発明の電極材は厚み方向のポイント圧縮保持率の裏面／表面比率を０．９５以下にする事によって電極構成時に厚み方向での非溝部分が優先的に圧縮されて溝をつぶれにくくし、電解層構成時の溝の損失を低減せしめるものである。これにより運転中においても通液圧損低減に有効な溝を確保する事ができる。
【００６５】
【発明の効果】
本発明の電極材を用いることにより、各種電解槽を利用する分野において通液圧力損失を低減することが出来、送液ポンプの負荷が減少する事によってポンプ稼動のためのエネルギー消費量を減少せしめることが出来る。それにより電池としての全エネルギー効率を高めることができる。これらのことは特にレドックスフロー型電池にとって効果的である。
【図面の簡単な説明】
【図１】図１にレドックスフロー型電池等の流通型電解槽を用いた電池の概略図を示す。
【図２】図２に本発明の実施例を示す電極材を有する液流通型電解槽の分解斜視模式図を示す。
【図３】図３は本発明の実施例を示す電極材の斜視模式図を示す。
【符号の説明】
１…集電板
２…スペーサ
３…イオン交換膜
４ａ，ｂ…通液路
５…電極
６…正極液タンク
７…負極液タンク
８，９…送液ポンプ
１０…液流入口、
１１…液流出口[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode material, and more particularly to a grooved electrode material used in a liquid flow type electrolytic cell used in a redox flow battery.
[0002]
[Prior art]
In recent years, the demand for clean electrical energy has increased rapidly, and the fields using electrolytic cells are increasing accordingly. Typical examples include various batteries such as primary, secondary, and fuel cells, and electrolysis industries such as electroplating, salt electrolysis, and electrosynthesis of organic compounds. The electrodes used in these electrolytic cells include an electrode itself that is often found in batteries such as lead-acid batteries as an active material, and a reaction field that promotes the electrochemical reaction of the active material. There are things that work and the electrode itself does not change. The latter electrode is mainly applied to new secondary batteries and the electrolysis industry.
[0003]
Among the new-type secondary batteries, there is a redox flow type battery. This battery is composed of an external tank and an electrolytic cell for storing an electrolytic solution, and an electrolytic solution containing an active material is supplied from the external tank to the electrolytic cell. Electrochemical energy conversion, that is, charge / discharge is performed on the incorporated electrode. In general, in charging and discharging, the electrolytic solution is circulated between the external tank and the electrolytic cell, so that the electrolytic cell has a liquid flow type structure as shown in FIG. The liquid flow type electrolytic cell is referred to as a single cell, and this is used as a minimum unit alone or in multiple layers. Since the electrochemical reaction in the liquid flow type electrolytic cell is a heterogeneous phase reaction that occurs on the electrode surface, it generally involves a two-dimensional electrolytic reaction field. If the electrolytic reaction field is two-dimensional, there is a drawback that the reaction amount per unit volume of the electrolytic cell is small. Therefore, the electrochemical reaction field has been three-dimensionalized in order to increase the reaction amount per unit area, that is, the current density. FIG. 2 is a schematic view of a liquid flow type electrolytic cell having a three-dimensional electrode.
[0004]
In the electrolytic cell, there are two current collector plates 1 opposed to each other, an ion exchange membrane 3 is disposed between them, and a flow of electrolyte along the current collector plate 1 by spacers 2 on both sides of the ion exchange membrane 3. Paths 4a and 4b are formed. A porous electrode material 5 such as a carbon fiber aggregate is disposed in at least one of the flow passages 4a and 4b, and thus a three-dimensional electrode is configured.
[0005]
In a liquid flow type electrolytic cell composed of a three-dimensional electrode having such an electrode material, a liquid feed pump is used to supply a liquid reaction active material to the electrolytic cell when charging / discharging. Less energy is required, and a pump with good pump power efficiency is used. However, when a liquid reaction active material is supplied to the electrolytic cell, a liquid passing pressure loss inevitably occurs. In this case, when a loss of liquid flow pressure occurs, it is necessary to increase the pumping amount in order to secure a predetermined flow rate, and the energy consumption for operating the pump increases. In this case, especially in a rechargeable secondary battery such as a redox flow battery, the total energy efficiency of the battery itself is obtained by subtracting the energy required for liquid transfer from the power efficiency of charge / discharge as a loss. At best, if the pump power is large, the energy loss is large and the overall energy efficiency of the battery is lowered. Therefore, the lower the fluid pressure loss due to the electrolytic cell, the better.
[0006]
The electrolytic bath pressure loss depends on the porous electrode material of the three-dimensional electrode and others (electrolyzer piping, manifold, etc.). Here, when the porous electrode material having the three-dimensional electrode has the same density, increasing the thickness of the porous electrode material forming the three-dimensional electrode and increasing the thickness of the spacer can reduce the flow rate of the electrolyte. Liquid pressure loss can be reduced, and the load on the pump can be reduced. However, increasing the thickness of the three-dimensional electrode increases the amount of the electrode material used, resulting in a new problem of increasing the total cost of the battery.
[0007]
In order to solve this problem, Japanese Patent Laid-Open No. 63-200467 proposes a carbonaceous electrode material of a knitted fabric composed of a thicker yarn of No. 5 or more and a thinner yarn in a direction crossing the thick yarn. However, with this electrode material, the thick and / or thin threads that make up the electrode material fall off or become fuzzy, and the shape is not stable and cannot be cut accurately when cut to a predetermined size. There has occurred. Therefore, the inventor of the present invention invented a carbonaceous nonwoven fabric having grooves of a predetermined size in Japanese Patent Application Laid-Open No. 08-287923. However, according to the present invention, when an electrolytic layer is formed by sandwiching an ion exchange membrane with an electrode material and constructing an electrolysis layer, the groove is reduced by the pressure of the pressure contact, and a liquid flow loss as expected cannot be obtained. occured.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and suppresses a decrease in the groove caused by the pressure of the pressure contact in the configuration of the electrolytic layer, and suppresses a loss of liquid passing pressure during the liquid flow without impairing the basic performance of the electrode material. The object is to provide an electrode material.
[0009]
In order to solve the above-mentioned problems, the present inventors have intensively studied focusing on the compression retention rate of the groove of the electrode material. As a result, the points on the back surface not constituting the groove with respect to the point compression retention rate of the surface constituting the groove It has been found that when the compression retention ratio is less than a certain value, it is possible to suppress the loss of liquid passing pressure during liquid circulation without impairing the basic performance of the electrode material.
[0010]
In addition, the present inventors have found that the grooved electrode material is obtained by carbonizing a carbonized nonwoven fabric having a certain amount of an organic binder by heating and pressurizing under certain conditions to form a groove. .
[0011]
As a result of further studies based on the above findings, the present inventors have completed the present invention.
[0012]
[Means for Solving the Problems]
That is, the present invention is a grooved electrode material made of a nonwoven fabric mainly composed of carbonaceous fibers, and has no point compression retention rate (A) at the bank portion of the surface (surface) having the groove of the nonwoven fabric and no groove. The ratio (B / A) to the point compression retention rate (B) of the surface (back surface) is 0.95 or less. For liquid flow electrolytic cell Grooved electrode material (Hereinafter simply referred to as grooved electrode material) Is to provide.
[0013]
In a preferred embodiment of the grooved electrode material of the present invention, the basis weight of the nonwoven fabric is 100 g / m. ² The bulk density of the nonwoven fabric is 0.05 g / cc to 0.15 g / cc.
[0014]
In a preferred embodiment of the grooved electrode material of the present invention, the width of the groove is 1 mm to 5 mm, and the depth of the groove is 20% or more of the thickness of the nonwoven fabric.
[0015]
A preferred embodiment of the grooved electrode material of the present invention is that the groove has two or more grooves, and the interval between adjacent grooves is larger than the groove width.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The grooved electrode of the present invention is required to be a grooved electrode material made of a nonwoven fabric mainly composed of carbon fibers. Mainly because it is suitable for use in a liquid flow electrolytic cell, that is, a three-dimensional electrode in which an electrode material is present on at least one of both electrodes through a diaphragm and is pressed by a current collector, particularly a redox flow battery. .
[0018]
That is, the present invention is a grooved electrode material made of a nonwoven fabric mainly composed of carbonaceous fibers, and the point compression rate (A) of the bank portion of the surface having the groove of the nonwoven fabric and the point compression of the surface without the groove A grooved electrode material having a ratio (B / A) to the ratio (B) of 0.95 or less is provided.
The grooved electrode material of the present invention has a point compression retention rate at the bank portion of the surface (front surface) having the groove of the nonwoven fabric and the surface without the groove (back surface) in order to reduce the decrease of the groove when forming the electrode. ) With a difference in compression retention rate, the point compression retention rate (A) of the bank portion of the non-woven fabric grooved surface (front surface) and the point compression retention rate (B) of the non-grooved surface (back surface) And the ratio (B / A) is 0.95 or less, more preferably 0.94 or less. If it is greater than 0.95, the compression retention of the front and back surfaces will approach, so even if a deep groove is formed, the groove disappears due to the pressure applied when forming as an electrode, and the liquid permeability deteriorates. Because.
[0019]
In the present invention, the compression retention is calculated by measuring the amount of change in thickness from a load of 4 g-f to 50 g-f using a thickness gauge having a spherical tip at the front and back surfaces.
[0020]
In addition, in this invention, a groove | channel means the thing in which a concave state is continuously formed in the nonwoven fabric cross section, and forms the flow path (FIG. 3).
[0021]
The basis weight of the nonwoven fabric constituting the grooved electrode material of the present invention is at least 100 g / m. ² Or more, preferably 100 to 800 g / m ² Is more preferable. The basis weight is 100 g / m ² If it is less than this, the reaction field as a three-dimensional electrode material is insufficient, and the internal resistance of the electrolytic layer increases.
[0022]
The bulk density of the nonwoven fabric constituting the grooved electrode material of the present invention is preferably 0.05 to 0.15 g / cc, more preferably 0.06 to 0.14 g / cc. When the bulk density is less than 0.05 g / cc, the contact property with the current collector plate is low and the contact resistance of the electrolytic cell is increased. On the contrary, when the bulk density exceeds 0.15 g / cc, electrolysis is performed. The liquid tends to concentrate in the groove and circulate, so that the liquid does not diffuse uniformly into the electrode material, and the utilization factor of the electrode material decreases.
[0023]
In the present invention, it is preferable that the range of the weight per unit area and the density is satisfied, and the thickness of the electrode material is larger than the thickness of the spacer 2 in FIG. 2, especially if the thickness is about 1.5 to 3 times the spacer thickness. More preferred.
[0024]
The groove width of the grooved electrode material of the present invention is preferably 1 to 5 mm, and the groove depth is preferably 20% or more with respect to the thickness of the nonwoven fabric. When the width of the groove is less than 1 mm, or when the depth of the groove is less than 20% of the thickness, the groove disappears when the electrode material is pressure-contacted at the time of producing the electrolytic cell, and the liquid pressure loss Will increase. When the groove width exceeds 5 mm, the groove disappears when the electrode material is pressed.
[0025]
The groove interval of the grooved electrode material of the present invention is preferably larger than the groove width. When the interval between the grooves is smaller than the width of the grooves, the bondability between the electrode material and the current collector plate is lowered and the contact resistance is increased.
[0026]
The number of grooves is preferably set so that the total cross-sectional area of the groove of the grooved electrode material of the present invention is 1% or more with respect to the product of the electrolytic layer flow path width and the electrode material thickness.
In addition, the total cross-sectional area (SMn) of the groove | channel of an electrode material is calculated | required by the following formula 1.
Total cross-sectional area of electrode material groove (SMn) = tM × DM × n (Formula 1)
Where tM: groove depth
DM: Width of groove
n: number of grooves
[0027]
In the grooved nonwoven fabric of the present invention, the groove may be disposed so that the groove is disposed so as to face the ion exchange membrane at the center of the electrolytic cell, or may be disposed so as to face the current collecting plate. However, the grooves are preferably arranged in parallel with the flow path of the electrolyte.
[0028]
The manufacturing method of the electrode material with a groove | channel of this invention is 1-500 kg / cm of the carbonizable nonwoven fabric containing 0.1-10 weight% of organic binders. ² It is necessary to carbonize after forming a groove | channel by heat-press molding at 100-200 degreeC for 0.1 to 5 minutes by the pressure of this.
[0029]
The carbonizable non-woven fabric is not particularly limited. For example, isotropic pitch or mesoface pitch precursor fiber, cellulose fiber, cured novolac fiber, polyvinyl alcohol fiber, aromatic polyamide fiber, poly-p-phenylene. Although there are benzoxazole fibers and the like, it is particularly preferable to use as a raw material a flame resistant fiber obtained by making a polyacrylonitrile fiber flame resistant by a known method.
[0030]
The method for making the carbonizable material into a nonwoven fabric is not particularly limited, but, for example, a method of defibrating with a card and making a multilayered web with a needle punch is suitably used. . In order to facilitate the formation of the grooves, non-woven fabrics of different fiber materials may be laminated in multiple layers, or non-woven fabrics may be created by mixing different fiber materials.
[0031]
Furthermore, the method for providing the groove is to place a mold having a predetermined peak width, peak-to-peak interval, and height on the nonwoven fabric, and place the mold on the nonwoven fabric at a temperature of 100 to 200 ° C. for 0.1 to 5 minutes, Pressure 1-500kg / cm ² To obtain a grooved nonwoven fabric. Here, in order to obtain a material having a low ratio of the compression / retention ratio of the back surface / front surface in the thickness direction, it is preferable to add 0.1 to 10% by weight of an organic binder to the raw material made into a nonwoven fabric and perform grooving.
[0032]
If these grooving conditions and the amount of the binder are out of the above ranges, the ratio of the backside / surface compression retention ratio in the thickness direction is close to 1, and there is no difference in the compression retention ratio of the front and back surfaces. Does not remain and liquid permeability deteriorates.
[0033]
The pressure is a value obtained by dividing the load applied to the press (= cylinder cross-sectional area of the press × gauge pressure) by the area of the nonwoven fabric to be pressed.
[0034]
The above organic binders include acrylic, cellulose, polyvinyl alcohol, epoxy resin, vinyl acetate, and phenol resin, but especially phenol resin that forms stable grooves even after firing by heat curing and carbonization. Is desirable. In order to have a difference in the compression retention rate between the front and back sides, the binder is incorporated into the nonwoven fabric. When the powder binder is spread on the surface, the binder is fixed inside the nonwoven fabric by spraying from the top and sucking it from below after spreading. It is desirable to do. Moreover, about the nonwoven fabric in which provision of a groove | channel is difficult, you may bond and integrate with the nonwoven fabric which formed the groove | channel previously.
[0035]
The grooved nonwoven fabric thus obtained is carbonized at 800 to 2500 ° C. in an inert atmosphere to impart conductivity. Furthermore, after carbonization, in order to improve the wettability with the electrolytic solution, surface oxidation is performed in the air at 500 to 1000 ° C. to obtain a carbonaceous electrode material. The carbonization method and oxidation method may be known methods, but the carbon crystal plane spacing is 3.7 angstroms or less, and the number of surface oxygen atoms by ESCA surface analysis is at least 7% of the number of carbon atoms. It is preferable.
[0036]
The basis weight of the electrode material, the electrode material thickness, the bulk density, the groove thickness, the groove depth, the groove width, the groove interval, the back / surface ratio of the compression retention rate in the thickness direction, and the flow pressure loss are as follows. It is measured as follows.
[0037]
(1) Weight per unit (W)
A 10 cm square (dimension: a) sample used for measuring the flow pressure loss is dried at 100 ° C. for 1 hour, allowed to cool with a desiccator, and then weighed with an electronic balance (weight: w ′). Further, the basis weight is calculated by the following formula.
Per unit weight W = w '/ a ^ 2
[0038]
(2) Nonwoven thickness (t)
Align the five corners of the 10 cm square sample and the center part of the sample used for measuring the flow-through pressure loss with the bank part of the sample at the center of the measuring element, and apply it to the digital linear gauge D10 (maximum load 100 g-f) manufactured by Ozaki Mfg. Measure using the stylus of, read up to 2 digits after the decimal point, and average the values to the nearest decimal place. The unit used is millimeter.
[0039]
(3) Bulk density
Calculated by dividing the basis weight by the electrode material thickness. (Unit: g / cc)
[0040]
(4) Groove thickness (tm)
Measure 6 points of thickness of 10cm square groove of sample used for measurement of fluid pressure loss on dial thickness gauge (model G: maximum load 180g-f) manufactured by Ozaki Mfg. Co., Ltd. with contact surface dimensions of 1mm x 10mm. Read and average up to 2 digits and round off to the nearest decimal place. The unit used is millimeter.
[0041]
(5) Groove depth (tM)
The difference between the value of the groove thickness in (4) and the value of the electrode material thickness in (2) is defined as the groove depth (unit: millimeter).
[0042]
(6) Groove width (DM)
Measure the groove width with a Digimatic caliper (Series 500) manufactured by Mitutoyo Corp., read up to two digits after the decimal point, and round off to the nearest decimal place.
[0043]
(7) Groove spacing (PM)
Both ends of the adjacent groove, that is, the bank portion (FIG. 3) are measured with a Digimatic caliper (Series 500) manufactured by Mitutoyo Corporation, read to two digits after the decimal point, and rounded off to the minimum. (Unit: mm)
[0044]
(8) Back / surface ratio of point compression retention in the thickness direction
A measuring instrument (spherical measuring instrument X-1 manufactured by Ozaki Seisakusho Co., Ltd.) is attached to a compression thickness tester, and a test piece having a size of 25 mm × 10 mm is prepared. After adjusting the zero point at the time of zero load, a measuring element is put on the bank portion of the surface of the test piece, a load of 4 g-f is applied, and the thickness at that time is read (Xa4). Then, it is compressed to 50 g-f, and the thickness at this time is read (Xa50). From these data, the point compression retention rate of the surface is obtained by Equation 2-1.
Surface point compression retention (A) = Xa50 / Xa4 (Formula 2-1)
Furthermore, the above-mentioned measuring piece is turned over, a measuring element is put on the portion corresponding to the bank portion, a load of 4 g-f is applied, and the thickness at that time is read (Xb4). Then, it is compressed to 50 g-f, and the thickness at this time is read (Xb50). From these data, the point compression retention on the back surface is obtained by Equation 2-2.
Back point compression retention (B) = Xb50 / Xb4 (Formula 2-2)
The ratio of the compression retention ratio of the front surface and the back surface is obtained by Equation 2-3.

[0045]
(9) Fluid pressure loss
A liquid-flowing electrolytic layer having the same shape as the liquid-flowing electrolytic layer shown in FIG. 2 and formed of a spacer (2) having a thickness of 20 cm in the liquid-flowing direction, a width direction (channel width) of 10 cm, and a predetermined thickness is prepared. Cut the electrode material into 10cm squares. Ion-exchanged water with a liquid volume of 10 liters / hour is circulated, and the flow pressure loss at the inlet / outlet of the electrolytic cell is measured. It measures similarly by the system which does not install an electrode material as a blank, and makes the difference of a measured value and a blank measured value the liquid pressure loss of an electrode material.
[0046]
【Example】
Hereinafter, the present invention will be described with reference to examples and comparative examples.
Example 1
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is made flame resistant at 250 ° C. in air, and then made into a felt by using the short fiber of the flame resistant fiber to have a basis weight of 900 g / m. ² A nonwoven fabric having a thickness of 6.1 mm was obtained. 18.9 g / m of powder novolak resin (BRP534A manufactured by Showa Polymer Co., Ltd.) on the nonwoven fabric. ² The binder was fixed on the nonwoven fabric by suction at a rate of 3.0 m / sec from the lower side to obtain a binder-containing flameproof nonwoven fabric. Further, the nonwoven fabric is cut into a 300 mm square, and on top of it, a 300 mm square aluminum mold having a peak width of 2.0 mm, a peak height of 10 mm, a peak length of 300 mm, and a peak-to-peak interval of 13 mm, the mountain faces the nonwoven fabric. And set in a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves.
The flame-resistant fiber nonwoven fabric was heated to 1500 ° C. at a temperature rising rate of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 700 ° C. to a weight yield of 93% to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0047]
(Comparative Example 1)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is made flame resistant at 250 ° C. in air, and then made into a felt by using the short fiber of the flame resistant fiber to have a basis weight of 900 g / m. ² A nonwoven fabric having a thickness of 6.1 mm was obtained. The nonwoven fabric is cut into a 300 mm square, and a 300 mm square aluminum mold having a crest with a crest width of 2.0 mm, a crest height of 10 mm, a crest length of 300 mm, and a crest-to-crest interval of 13 mm is arranged so that the crest faces the nonwoven fabric. Is set on a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm. ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves. The flame-resistant fiber nonwoven fabric was heated to 1500 C at a heating rate of 10 ° C./min in an inert gas, held at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 700 ° C. to a weight yield of 93% to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0048]
(Example 2)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to a basis weight of 600 g / m. ² A nonwoven fabric having a thickness of 4.8 mm was obtained. 18.9 g / m of powder novolak resin (BRP534A manufactured by Showa Polymer Co., Ltd.) on the nonwoven fabric. ² Then, the binder was fixed on the nonwoven fabric by suction from below at a suction speed of 2.6 m / sec to obtain a binder-containing flameproof nonwoven fabric. Further, the nonwoven fabric is cut into a 300 mm square, and on top of it, a 300 mm square aluminum mold having a peak width of 2.0 mm, a peak height of 10 mm, a peak length of 300 mm, and a peak-to-peak interval of 13 mm, the mountain faces the nonwoven fabric. And set in a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves.
The flame-resistant fiber nonwoven fabric was heated to 1300 C at a heating rate of 10 ° C./min in an inert gas, held at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 650 ° C. until a weight yield of 93% was obtained to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0049]
(Comparative Example 2)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to a basis weight of 600 g / m. ² A nonwoven fabric having a thickness of 4.8 mm was obtained. The nonwoven fabric is cut into a 300 mm square, and a 300 mm square aluminum mold having a crest with a crest width of 2.0 mm, a crest height of 10 mm, a crest length of 300 mm, and a crest-to-crest interval of 13 mm is arranged so that the crest faces the nonwoven fabric. Is set on a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm. ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves. The flame resistant fiber nonwoven fabric was heated to 1300 ° C. at a rate of temperature increase of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 650 ° C. until a weight yield of 93% was obtained to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0050]
(Example 3-1)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to give a basis weight of 500 g / m. ² A nonwoven fabric having a thickness of 4.6 mm was obtained. 18.9 g / m of powder novolak resin (BRP534 manufactured by Showa Polymer Co., Ltd.) on the nonwoven fabric. ² Then, the binder was fixed on the nonwoven fabric by suction from below at a suction speed of 2.6 m / sec to obtain a binder-containing flameproof nonwoven fabric. Further, the nonwoven fabric is cut into a 300 mm square, and on top of it, a 300 mm square aluminum mold having a crest of 2.0 mm, a crest height of 10 mm, a crest length of 300 mm, and a crest-to-crest interval of 23 mm, the crest faces the nonwoven fabric. And set in a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves.
The flame resistant fiber nonwoven fabric was heated to 1300 ° C. at a rate of temperature increase of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 650 ° C. until a weight yield of 93% was obtained to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0051]
( Reference example ) Polyacrylonitrile (PAN) fibers having an average fiber diameter of 16 μm are made flame resistant at 250 ° C. in the air, and then made into felt using the short fibers of the flame resistant fibers to obtain a nonwoven fabric having a basis weight of 500 g / m 2 and a thickness of 4.6 mm. It was. This nonwoven fabric is dipped in a resol emulsion (BRL 2854 manufactured by Showa Polymer Co., Ltd.) 0.3% by weight in a water bath, squeezed with a mangle to obtain a pickup rate of 200%, and dried for 1 hour at 100 ° C. Got. Further, the nonwoven fabric is cut into a 300 mm square, and an aluminum mold 300 mm square having a crest of 2.0 mm, a crest height of 10 mm, a crest length of 300 mm, and a crest-to-crest interval of 23 mm is placed on the nonwoven fabric. Thus, it was set in a heat press apparatus having a temperature of 180 ° C. and a cylinder diameter of 160 mm, and pressed at a pressure of 20 kg / cm 2 for 1 minute to obtain a grooved flame resistant fiber nonwoven fabric. The flame resistant fiber nonwoven fabric was heated to 1300 ° C. at a rate of temperature increase of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 650 ° C. until a weight yield of 93% was obtained to obtain a grooved carbonaceous fiber nonwoven fabric. The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0052]
(Comparative Example 3)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to give a basis weight of 500 g / m. ² A nonwoven fabric having a thickness of 4.8 mm was obtained. The nonwoven fabric is cut into a 300 mm square, and a 300 mm square aluminum mold having a peak width of 2.0 mm, a peak height of 10 mm, a peak length of 300 mm, and a peak-to-peak interval of 23 mm is arranged so that the peak faces the nonwoven fabric. Is set on a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm. ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves. The flame resistant fiber nonwoven fabric was heated to 1300 ° C. at a rate of temperature increase of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 650 ° C. until a weight yield of 93% was obtained to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0053]
Example 4
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to give a basis weight of 450 g / m. ² A nonwoven fabric having a thickness of 4.5 mm was obtained. 18.9 g / m of powder novolak resin (BRP534A manufactured by Showa Polymer Co., Ltd.) on the nonwoven fabric. ² Then, the binder was fixed on the nonwoven fabric by suction from below at a suction speed of 2.6 m / sec to obtain a binder-containing flameproof nonwoven fabric. Further, the nonwoven fabric is cut into a 300 mm square, and on top of it, a 300 mm square aluminum mold having a peak width of 2.0 mm, a peak height of 10 mm, a peak length of 300 mm, and a peak-to-peak interval of 13 mm, the mountain faces the nonwoven fabric. And set in a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves.
The flame resistant fiber nonwoven fabric was heated to 1300 ° C. at a rate of temperature increase of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 650 ° C. until a weight yield of 93% was obtained to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0054]
(Comparative Example 4)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to give a basis weight of 450 g / m. ² A nonwoven fabric having a thickness of 4.5 mm was obtained. The non-woven fabric is cut into a 300 mm square, and a 300 mm square aluminum mold having a crest of 2.0 mm, a crest height of 10 mm, a crest length of 300 mm, and a crest between crests of 13 mm is placed on the nonwoven fabric so that the crest faces the nonwoven fabric. Is set on a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm. ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves. The flame resistant fiber nonwoven fabric was heated to 1300 ° C. at a rate of temperature increase of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 650 ° C. until a weight yield of 93% was obtained to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0055]
(Example 5)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to give a basis weight of 350 g / m. ² A nonwoven fabric having a thickness of 4.0 mm was obtained. 18.9 g / m of powder novolak resin (BRP534A manufactured by Showa Polymer Co., Ltd.) on the nonwoven fabric. ² Then, the binder was fixed on the nonwoven fabric by suction from below at a suction speed of 2.6 m / sec to obtain a binder-containing flameproof nonwoven fabric. Further, the nonwoven fabric is cut into a 300 mm square, and an aluminum mold having a crest of 2.0 mm, a crest height of 10 mm, a crest length of 300 mm, and a crest-to-crest interval of 15 mm is placed on the nonwoven fabric. And set in a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves.
The flame resistant fiber nonwoven fabric was heated to 1300 ° C. at a rate of temperature increase of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 650 ° C. until a weight yield of 93% was obtained to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0056]
(Comparative Example 5)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to give a basis weight of 350 g / m. ² A nonwoven fabric having a thickness of 4.0 mm was obtained. The nonwoven fabric is cut into a 300 mm square, and a 300 mm square aluminum mold having a crest with a crest width of 2.0 mm, a crest height of 10 mm, a crest length of 300 mm, and a crest-to-crest interval of 13 mm is arranged so that the crest faces the nonwoven fabric. Is set on a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm. ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves. The flame resistant fiber nonwoven fabric was heated to 1300 ° C. at a rate of temperature increase of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 650 ° C. until a weight yield of 93% was obtained to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0057]
(Example 6)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber, so that the basis weight is 860 g / m. ² A nonwoven fabric having a thickness of 6.0 mm was obtained. 18.9 g / m of powder novolak resin (BRP534A manufactured by Showa Polymer Co., Ltd.) on the nonwoven fabric. ² The binder was fixed on the nonwoven fabric by suction at a rate of 3.0 mm / sec from the lower side to obtain a binder-containing flameproof nonwoven fabric. Further, the nonwoven fabric is cut into a 300 mm square, and on the top, a 300 mm square aluminum mold having a crest of 2.0 mm crest, a crest height of 1.5 mm, a crest length of 300 mm, and a crest-to-crest interval of 6 mm Is placed on a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and the pressure is 20 kg / cm. ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves.
The flame-resistant fiber nonwoven fabric was heated to 1500 ° C. at a temperature rising rate of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 700 ° C. to a weight yield of 93% to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0058]
(Comparative Example 6)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber, so that the basis weight is 860 g / m. ² A nonwoven fabric having a thickness of 6.0 mm was obtained. The nonwoven fabric is cut into a 300 mm square, and a 300 mm square aluminum mold having a crest with a crest width of 2.0 mm, a crest height of 1.5 mm, a crest length of 300 mm, and a crest-to-crest spacing of 6 mm is formed on the nonwoven fabric. It is piled so as to face each other, set in a heat press apparatus with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves. The flame-resistant fiber nonwoven fabric was heated to 1500 ° C. at a temperature rising rate of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 700 ° C. to a weight yield of 93% to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric Table 1 shows the spacer thickness at the time of pressure loss measurement.
[0059]
(Example 7)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to have a basis weight of 930 g / m. ² A nonwoven fabric having a thickness of 6.2 mm was obtained. 31.2 g / m of powder novolak resin (BRP534A manufactured by Showa Polymer Co., Ltd.) on the nonwoven fabric. ² The binder was fixed on the nonwoven fabric by suction at a rate of 3.0 m / sec from the lower side to obtain a binder-containing flameproof nonwoven fabric. Further, the nonwoven fabric is cut into a 300 mm square, and on the top, a 300 mm square aluminum mold having a crest of 2.0 mm crest, a crest height of 1.5 mm, a crest length of 300 mm, and a crest-to-crest interval of 6 mm Is placed on a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and the pressure is 20 kg / cm. ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves.
The flame-resistant fiber nonwoven fabric was heated to 1500 ° C. at a temperature rising rate of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 700 ° C. to a weight yield of 93% to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0060]
(Comparative Example 7)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to have a basis weight of 930 g / m. ² A nonwoven fabric having a thickness of 6.2 mm was obtained. The nonwoven fabric is cut into a 300 mm square, and a 300 mm square aluminum mold having a crest with a crest width of 2.0 mm, a crest height of 1.5 mm, a crest length of 300 mm, and a crest-to-crest spacing of 6 mm is formed on the nonwoven fabric. It is piled so as to face each other, set in a heat press apparatus with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves. The flame-resistant fiber nonwoven fabric was heated to 1500 ° C. at a temperature rising rate of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 700 ° C. to a weight yield of 93% to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0061]
(Example 8)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to give a basis weight of 920 g / m. ² A nonwoven fabric having a thickness of 6.2 mm was obtained. 31.2 g / m of powder novolak resin (BRP534A manufactured by Showa Polymer Co., Ltd.) on the nonwoven fabric. ² The binder was fixed on the nonwoven fabric by suction at a rate of 3.0 m / sec from the lower side to obtain a binder-containing flameproof nonwoven fabric. Further, the nonwoven fabric is cut into a 300 mm square, and a 300 mm square aluminum mold having a crest with a crest width of 3.0 mm, a crest height of 1.5 mm, a crest length of 300 mm, and a crest-to-crest interval of 6 mm is formed on the crest. Is placed on a heat press machine with a temperature of 180 ° C. and a cylinder diameter of 160 mm, and the pressure is 20 kg / cm. ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves.
The flame-resistant fiber nonwoven fabric was heated to 1500 ° C. at a temperature rising rate of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 700 ° C. to a weight yield of 93% to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0062]
(Comparative Example 8)
A polyacrylonitrile (PAN) fiber having an average fiber diameter of 16 μm is flame-resistant in air at 250 ° C., and then felted using the short fiber of the flame-resistant fiber to have a basis weight of 930 g / m. ² A nonwoven fabric having a thickness of 6.2 mm was obtained. The nonwoven fabric is cut into a 300 mm square, and a 300 mm square aluminum mold having a peak width of 3.0 mm, a peak height of 1.5 mm, a peak length of 300 mm, and a peak-to-peak interval of 6 mm is formed on the nonwoven fabric. It is piled so as to face each other and set in a heat press apparatus having a temperature of 180 ° C. and a cylinder diameter of 160 mm, and a pressure of 20 kg / cm. ² Was pressed for 1 minute to obtain a flame-resistant nonwoven fabric with grooves. The flame-resistant fiber nonwoven fabric was heated to 1500 ° C. at a temperature rising rate of 10 ° C./min in an inert gas, kept at this temperature for 1 hour, carbonized, and then cooled to obtain a carbide. The carbide was oxidized in air at 700 ° C. to a weight yield of 93% to obtain a grooved carbonaceous fiber nonwoven fabric.
The basis weight, thickness, density, groove thickness, groove depth, groove width, groove interval, back surface / surface ratio of point compression retention in the thickness direction, liquid pressure loss and liquid flow of the grooved carbon fiber nonwoven fabric The spacer thickness at the time of measuring the pressure loss is shown in Table 1.
[0063]
[Table 1]

[0064]
[Action]
The electrode material of the present invention makes the non-grooved portion in the thickness direction preferentially compressed at the time of electrode configuration by making the back surface / surface ratio of the point compression retention rate in the thickness direction 0.95 or less, making the groove difficult to collapse, This is to reduce the loss of the groove when the electrolytic layer is constructed. As a result, it is possible to ensure a groove effective in reducing the fluid pressure loss even during operation.
[0065]
【The invention's effect】
By using the electrode material of the present invention, it is possible to reduce the flow pressure loss in the field using various electrolytic cells, and to reduce the energy consumption for pump operation by reducing the load of the liquid feed pump. I can do it. Thereby, the total energy efficiency as a battery can be improved. These are particularly effective for redox flow batteries.
[Brief description of the drawings]
FIG. 1 is a schematic view of a battery using a flow-type electrolytic cell such as a redox flow battery.
FIG. 2 is an exploded perspective schematic view of a liquid flow type electrolytic cell having an electrode material showing an embodiment of the present invention.
FIG. 3 is a schematic perspective view of an electrode material showing an embodiment of the present invention.
[Explanation of symbols]
1 ... current collector
2 ... Spacer
3 ... Ion exchange membrane
4a, b ... Liquid passage
5 ... Electrode
6 ... Cathode tank
7 ... Anode solution tank
8, 9 ... Liquid feed pump
10 ... Liquid inlet,
11 ... Liquid outlet

Claims

炭素質繊維を主成分とする不織布からなる溝付き電極材であって、前記不織布の溝を有する面（表面）の土手部分のポイント圧縮保持率（Ａ）と溝のない面（裏面）のポイント圧縮保持率（Ｂ）との比（Ｂ／Ａ）が０．９５以下であることを特徴とする液流通型電解槽用溝付き電極材。A grooved electrode material composed of a nonwoven fabric mainly composed of carbonaceous fibers, the point compression retention rate (A) of the bank portion of the surface (front surface) having the groove of the nonwoven fabric and the point of the surface without the groove (back surface) A grooved electrode material for a liquid flow type electrolytic cell , wherein the ratio (B / A) to the compression retention (B) is 0.95 or less.

前記不織布の目付量が１００ｇ／ｍ² 以上であり、且つ、前記不織布の嵩密度が０．０５ｇ／ｃｃ〜０．１５ｇ／ｃｃであることを特徴とする請求項１に記載の液流通型電解槽用溝付き電極材。 ^2. The liquid flow-type electrolysis according to claim 1, wherein the nonwoven fabric has a basis weight of 100 g / m ² or more, and the nonwoven fabric has a bulk density of 0.05 g / cc to 0.15 g / cc. Electrode material with groove for tank .

前記溝の幅が１ｍｍ〜５ｍｍであり、前記溝の深さが前記不織布の厚みの２０％以上であることを特徴とする請求項１又は２に記載の液流通型電解槽用溝付き電極材。 3. The grooved electrode material for a liquid-flowing electrolytic cell according to claim 1, wherein the groove has a width of 1 mm to 5 mm, and the depth of the groove is 20% or more of the thickness of the nonwoven fabric. .

前記溝を２以上有し、且つ、隣接する溝と溝との間隔が溝の幅より大きいことを特徴とする請求項１乃至３に記載の液流通型電解槽用溝付き電極材。4. The grooved electrode material for a liquid flow type electrolytic cell according to claim 1, wherein the groove has two or more grooves, and an interval between adjacent grooves is larger than a width of the groove.