JP2011124106A

JP2011124106A - Solid electrolyte fuel cell

Info

Publication number: JP2011124106A
Application number: JP2009281139A
Authority: JP
Inventors: Makoto Aoki; 信青木
Original assignee: Fuji Electric Co Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 2009-12-11
Filing date: 2009-12-11
Publication date: 2011-06-23
Anticipated expiration: 2029-12-11
Also published as: JP5333188B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte fuel cell in which an electrolyte and an ion conduction path of an electrode are connected and the electrode works effectively. <P>SOLUTION: In the solid electrolyte fuel cell having an electrolyte layer composed of a basic metal compound between an anode electrode and a cathode electrode, resin having ionic conductivity by an ion species the same as the ion species showing ionic conductivity to the basic metal compound is interposed between at least one electrode of either the anode electrode or the cathode electrode and the electrolyte layer, at least the one electrode and the electrolyte layer are jointed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、固体電解質形燃料電池に関し、特に、固体電解質形燃料電池のセル構造に関する。 The present invention relates to a solid oxide fuel cell, and more particularly to a cell structure of a solid oxide fuel cell.

燃料電池は、燃料の有する化学エネルギーを機械エネルギーや熱エネルギーを経由することなく直接電気エネルギーに変換する装置であり、高いエネルギー効率が実現可能である。良く知られた燃料電池の形態としては、電解質層を挟んで一対の電極を配置し、一方の電極（アノード側）に水素を含有する燃料ガスを供給するとともに他方の電極（カソード側）に酸素を含有する酸化ガスを供給するものであり、両極間で起きる電気化学反応を利用して起電力を得る。燃料電池は用いられる電解質の種類によって通常分類される。すなわち、リン酸を用いたリン酸形燃料電池（ＰＡＦＣ）、イオン導電性ポリマーを用いた固体高分子形燃料電池（ＰＥＦＣ）、イオン導電性セラミックスを用いた固体酸化物形燃料電池（ＳＯＦＣ）などに分類される。この内、ＳＯＦＣは金属化合物の一種であるジルコニアを電解質としており、８００℃以上のような高温で作動するので、電極に高価な白金触媒を必要としないという利点を有する。 A fuel cell is a device that directly converts chemical energy of fuel into electrical energy without passing through mechanical energy or thermal energy, and can achieve high energy efficiency. As a well-known form of a fuel cell, a pair of electrodes are arranged with an electrolyte layer in between, a fuel gas containing hydrogen is supplied to one electrode (anode side), and oxygen is supplied to the other electrode (cathode side). The electromotive force is obtained by utilizing an electrochemical reaction that occurs between the two electrodes. Fuel cells are usually classified according to the type of electrolyte used. That is, phosphoric acid fuel cell (PAFC) using phosphoric acid, solid polymer fuel cell (PEFC) using ion conductive polymer, solid oxide fuel cell (SOFC) using ion conductive ceramic, etc. are categorized. Among these, SOFC uses zirconia, which is a kind of metal compound, as an electrolyte, and operates at a high temperature such as 800 ° C. or more, and therefore has an advantage that an expensive platinum catalyst is not required for the electrode.

電解質として塩基性金属化合物を用いた電池構造の概略を図２に示す。図２に示される燃料電池で起きる電気化学反応を表す式を以下に示す。（１）はアノード側３１に於ける反応、（２）はカソード側３２に於ける反応を表し、燃料電池全体では（３）式に表す反応が進行する。 An outline of a battery structure using a basic metal compound as an electrolyte is shown in FIG. A formula representing an electrochemical reaction occurring in the fuel cell shown in FIG. 2 is shown below. (1) represents the reaction on the anode side 31, (2) represents the reaction on the cathode side 32, and the reaction represented by the formula (3) proceeds in the entire fuel cell.

Ｈ₂ ＋２ＯＨ^- → ２Ｈ₂Ｏ＋２ｅ^- （１）
１／２Ｏ₂ ＋Ｈ₂Ｏ＋２ｅ^- → ２ＯＨ^- （２）
Ｈ₂ ＋１／２Ｏ₂ → Ｈ₂Ｏ（３）
図２が示すように、カソード触媒層４２で発生した水酸基イオンＯＨ^-が電解質１を通ってアノード触媒層４１に到達し、アノード触媒層４１で発生した電子ｅ^-が外部回路を通ってカソード触媒層４２に到達する。塩基性金属化合物を用いた電解質材料はイオン伝導性が高く電子伝導性が低いため、燃料電池の電解質に適している。また、カソード側の酸素の還元反応が進行しやすいため、低温型燃料電池のカソード触媒として通常使用されている高価な白金が不要となる可能性がある。３００℃以下で高いイオン伝導率を示す（すなわち作動温度が３００℃以下である）アニオン伝導塩基性酸化物形燃料電池の研究が進められている（非特許文献１、２）。 H ₂ + 2OH ⁻ → 2H ₂ O + 2e ⁻ (1)
1 / 2O ₂ + H ₂ O + 2e ⁻ → 2OH ⁻ (2)
H ₂ + 1 / 2O ₂ → H ₂ O (3)
As shown in FIG. 2, the hydroxyl ion OH ⁻ generated in the cathode catalyst layer 42 reaches the anode catalyst layer 41 through the electrolyte 1, and the electrons e ⁻ generated in the anode catalyst layer 41 pass through the external circuit to the cathode catalyst. Layer 42 is reached. Electrolyte materials using basic metal compounds are suitable for fuel cell electrolytes because of their high ion conductivity and low electron conductivity. Moreover, since the reduction reaction of oxygen on the cathode side is likely to proceed, there is a possibility that expensive platinum that is usually used as a cathode catalyst for a low-temperature fuel cell is not necessary. Research on an anion conducting basic oxide fuel cell that exhibits high ionic conductivity at 300 ° C. or lower (that is, an operating temperature of 300 ° C. or lower) is in progress (Non-Patent Documents 1 and 2).

燃料電池の電極が有効に作動するには、電極と電解質層がうまく接合してイオン伝導パスがつながっている必要がある。電解質として金属化合物を用いる燃料電池では、固体同士（電解質と電極）を接合する必要がある。 In order for an electrode of a fuel cell to operate effectively, the electrode and the electrolyte layer must be well joined and an ion conduction path must be connected. In a fuel cell using a metal compound as an electrolyte, it is necessary to join solids (electrolyte and electrode) together.

竹口他3R30「アニオン伝導層状酸化物を電解質とする燃料電池の発電特性」電気化学会第７６回大会学術講演要旨集、457頁Takeguchi et al. 3R30 “Power generation characteristics of fuel cells using anion-conducting layered oxide as an electrolyte” Proceedings of the 76th Annual Meeting of the Electrochemical Society, 457 北海道大学「アニオン伝導塩基性酸化物燃料電池の研究開発」NEDO燃料電池・水素技術開発平成２０年度成果報告シンポジウム要旨集[2009年11月20日検索]、インターネット<http://www.nedo.go.jp/informations/other/210626/youshi0701.html>Hokkaido University “Research and Development of Anion Conducting Basic Oxide Fuel Cell” NEDO Fuel Cell and Hydrogen Technology Development Summary of FY2008 Results Report Symposium [searched on November 20, 2009], Internet <http: //www.nedo. go.jp/informations/other/210626/youshi0701.html>

しかしながら、従来の固体酸化物形燃料電池（ＳＯＦＣ）や非特許文献１、２に記載された、電解質として塩基性金属化合物を用いた燃料電池は、高温で焼結すると、電解質と電極の結合は強固になっても、電解質材料と電極材料が反応して異なる物質になることがあり、電解質と電極間のイオン伝導パスがつながらないという問題点があった。 However, when a conventional solid oxide fuel cell (SOFC) or a fuel cell using a basic metal compound as an electrolyte described in Non-Patent Documents 1 and 2 is sintered at a high temperature, the binding between the electrolyte and the electrode is Even if it is strengthened, the electrolyte material and the electrode material may react to become different substances, and there is a problem that the ion conduction path between the electrolyte and the electrode is not connected.

そこで、本発明は、上記従来技術の問題点を解決し、電解質と電極のイオン伝導パスがつながっており電極が有効に作動する固体電解質形燃料電池を提供することを課題とする。 SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems of the prior art and to provide a solid electrolyte fuel cell in which an ion conduction path between an electrolyte and an electrode is connected and the electrode operates effectively.

本発明の固体電解質形燃料電池は、アノード電極とカソード電極との間に、塩基性金属化合物からなる電解質層を備える固体電解質形燃料電池において、塩基性金属化合物にイオン伝導性を示すイオン種と同じイオン種によるイオン伝導性を有する樹脂を、アノード電極とカソード電極の少なくとも一方の電極と電解質層の間に介在させ、少なくとも一方の電極と電解質層を接合することとする。 The solid electrolyte fuel cell of the present invention is a solid electrolyte fuel cell comprising an electrolyte layer made of a basic metal compound between an anode electrode and a cathode electrode, and an ionic species exhibiting ionic conductivity to the basic metal compound. A resin having ion conductivity due to the same ion species is interposed between at least one of the anode electrode and the cathode electrode and the electrolyte layer, and at least one electrode and the electrolyte layer are joined.

上記構成において、上記樹脂が電極中に入り込むことによって、電極中に電解質を導入することができ、電極と電解質層間のイオン伝導パスがつながっている、電極と電解質の接合が実現される。 In the above configuration, when the resin enters the electrode, an electrolyte can be introduced into the electrode, and an electrode-electrolyte junction in which an ion conduction path between the electrode and the electrolyte layer is connected is realized.

本発明によれば、塩基性金属化合物にイオン伝導性を示すイオン種と同じイオン種によるイオン伝導性を有する樹脂を、アノード電極とカソード電極の少なくとも一方の電極と電解質層の間に介在させることで、当該電極と電解質層を接合しているので、当該電極と電解質の間にイオン伝導パスが形成され、当該電極が有効に作動できる。 According to the present invention, a resin having ionic conductivity due to the same ionic species as the ionic species exhibiting ionic conductivity in the basic metal compound is interposed between at least one of the anode electrode and the cathode electrode and the electrolyte layer. Thus, since the electrode and the electrolyte layer are joined, an ion conduction path is formed between the electrode and the electrolyte, and the electrode can be effectively operated.

本発明の実施形態に係る固体電解質形燃料電池セルの模式図である。1 is a schematic diagram of a solid oxide fuel cell according to an embodiment of the present invention. 電解質として塩基性金属化合物を用いた燃料電池構造の概略図である。It is the schematic of the fuel cell structure using a basic metal compound as electrolyte.

以下、本発明の実施の形態について、添付図面を参照して説明する。
図１は、本発明の実施形態に係る固体電解質形燃料電池セルの模式図である。燃料電池セルとは、電解質層を一対の電極で挟んだ構成のことを言う。本発明の実施形態に係る固体電解質形燃料電池は、電解質層１として塩基性金属化合物を用い、塩基性金属化合物にイオン伝導性を示すイオン種と同じイオン種によるイオン伝導性を有する樹脂２を電極３と電解質層１の間に介在させることで電極３と電解質層１を接合することを特徴とする。 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic view of a solid oxide fuel cell according to an embodiment of the present invention. A fuel cell refers to a configuration in which an electrolyte layer is sandwiched between a pair of electrodes. In the solid electrolyte fuel cell according to the embodiment of the present invention, a basic metal compound is used as the electrolyte layer 1, and the resin 2 having ion conductivity by the same ion species as the ion species exhibiting ion conductivity in the basic metal compound is used. The electrode 3 and the electrolyte layer 1 are joined by being interposed between the electrode 3 and the electrolyte layer 1.

塩基性金属化合物としては、３００℃以下で高いイオン伝導性を有するNaCo₂O₄, Bi₄Sr₁₄Fe₂₄O₅₆, LaFe₃Sr₃O₁₀等を用いることができる。
塩基性金属化合物電解質にイオン伝導性を示すイオン種ＯＨ^-と同じイオン種であるＯＨ^-によるイオン導電性を有する樹脂としては、トクヤマ製アニオン交換樹脂等を用いることができる。 As the basic metal compound, NaCo ₂ O ₄ , Bi ₄ Sr ₁₄ Fe ₂₄ O ₅₆ , LaFe ₃ Sr ₃ O ₁₀ or the like having high ion conductivity at 300 ° C. or lower can be used.
An anion exchange resin made by Tokuyama or the like can be used as the resin having ionic conductivity due to OH ⁻ which is the same ionic species as ionic species OH ⁻ which exhibits ionic conductivity in the basic metal compound electrolyte.

以下、本発明を実施例により詳細に説明するが、本発明はこの実施例に限定されるものではない。
Na₂CO₃、CoCO₃粉末をボールミルで混合した後、1000℃で2h焼成することによりNaCo₂O₄粉末を得る。得られた粉末を紛糾した後、金型を用いて直径20mm、厚さ1mmのディスク状に10MPaの圧力でNaCo₂O₄粉末を成型し、更に温度1100℃で3h焼成することにより、緻密な焼結体を製作できる。得られた焼結体を電解質とし、焼結体の両面にトクヤマ製アニオン交換樹脂を塗布した後、Pdメッキを施した200メッシュのNi金網を電極として押し当てて燃料電池セルとする。 EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this Example.
After mixing Na ₂ CO ₃ and CoCO ₃ powder with a ball mill, NaCo ₂ O ₄ powder is obtained by firing at 1000 ° C. for 2 hours. After the obtained powder is mixed, a NaCo ₂ O ₄ powder is molded into a disk shape having a diameter of 20 mm and a thickness of 1 mm using a mold at a pressure of 10 MPa, and further calcined at a temperature of 1100 ° C. for 3 hours to obtain a fine powder. A sintered body can be manufactured. The obtained sintered body is used as an electrolyte, and an anion exchange resin made by Tokuyama is applied to both surfaces of the sintered body, and then a Pd-plated 200 mesh Ni wire mesh is pressed as an electrode to form a fuel cell.

１電解質層
２樹脂
３電極
４１アノード触媒層
４２カソード触媒層

DESCRIPTION OF SYMBOLS 1 Electrolyte layer 2 Resin 3 Electrode 41 Anode catalyst layer 42 Cathode catalyst layer

Claims

In a solid electrolyte fuel cell including an electrolyte layer made of a basic metal compound between an anode electrode and a cathode electrode,
A resin having ionic conductivity due to the same ionic species as the ionic species exhibiting ionic conductivity in the basic metal compound is interposed between at least one electrode of the anode electrode and the cathode electrode and the electrolyte layer, and A solid electrolyte fuel cell, wherein one electrode and the electrolyte layer are joined.