Enhancement of electrolyte-electrode interfaces in solid oxide fuel cells

Abstract

In this study, solid oxide fuel cell (SOFC) electrolyte layers produced by tape casting method are pressed together with a metal mesh under different isostatic press pressures (10-60 MPa) to form surface patterns on the electrolyte. Effects of isostatic press pressure are investigated via profilometer, performance, impedance and microscopic analyses. Electrochemical measurements show that all cells with patterned electrolyte outperform the reference cell. The analyzes performed reveal that the improvement in cell performance is a result of the locally reduced electrolyte thickness as well as the increased electrolyte-electrode interface areas with surface patterning. The cell with patterned electrolyte pressed at 30 MPa pressure shows the highest peak performance of 0.373 W/cm2. For the reference cell, this value is measured as 0.320 W/cm2. At higher pressing pressures, cracks extending to the electrolyte are detected, especially in the cathode region, depending on the increased pattern depth. These cracks cause performance losses by limiting the improvement in the electrochemical reaction zones, which are expected to increase with the increase in the interfacial areas.

Keywords

• Solid oxide fuel cells
• Electrolyte-electrode interface
• Surface patterning

Katı oksit yakıt pillerinde elektrolit-elektrot arayüzey iyileştirilmesi

Öz

Bu çalışmada şerit döküm yöntemi ile imal edilen katı oksit yakıt pili (KOYP) elektrolit tabakaları metal bir elek ile birlikte farklı izostatik pres basınçları (10-60 MPa) altında preslenerek elektrolit üzerinde yüzey desenleri oluşturulmuştur. İzostatik pres basıncının etkileri; profilometre, performans, empedans ve mikroskop analizleri ile incelenmiştir. Elektrokimyasal ölçümler desenli elektrolite sahip bütün hücrelerin referans hücreden daha yüksek bir performans ortaya koyduğunu göstermiştir. Gerçekleştirilen analizler hücre performansındaki iyileşmenin desenleme ile artan elektrolit-elektrot arayüzey alanlarının yanı sıra lokal olarak azalan elektrolit kalınlığının da bir sonucu olduğunu ortaya çıkarmıştır. 0.373 W/cm2 ile en yüksek performansı ise 30 MPa basınçta preslenen desenli elektrolite sahip hücre sergilemiştir. Referans hücre için bu değer 0.320 W/cm2 olarak ölçülmüştür. Daha yüksek pres basınçlarında ise artan desen derinliğine bağlı olarak özellikle katot bölgesinde elektrolite kadar uzanan çatlaklar tespit edilmiştir. Bu çatlaklar, arayüzey alanındaki artışla artması beklenen elektrokimyasal reaksiyon bölgelerindeki iyileşmeyi sınırlayarak performans kayıplarına neden olmuştur.

Anahtar Kelimeler

• Katı Oksit Yakıt Pili
• Elektrolit-Elektrot Arayüzey
• Yüzey Desenleme.

Kaynakça

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