GÜMÜŞ AKIM TOPLAYICI MÜREKKEPLERİNDE FRİT BULUNMASININ KATI OKSİT YAKIT HÜCRESİ KATOTLARININ ELEKTROKİMYASAL PERFORMANSINA ETKİSİ

Abstract

Gümüş (Ag) içeren asıltılar (mürekkepler) orta sıcaklıklarda çalışan katı oksit yakıt hücresi (KOYH) katotları üzerine sıklıkla akım toplayıcı olarak uygulanırlar. Bu mürekkeplere camsı faz (frit) parçacıklarının ısıl işlem sonrasında altlığa iyi yapışma sağlanması amacıyla eklenmesi geleneksel olarak uygulanagelmiştir. Fakat bu parçacıkların Ag mürekkeplerine eklenmelerinin akım toplayıcı mikroyapısı ve performansı üzerindeki etkileri net olarak tespit edilmemiştir. Bu çalışmada gümüş mürekkeplerine frit eklenmesinin La_0.6Sr_0.4FeO₃ (LSF) ince film katotlarının elektrokimyasal performansına etkisi sunulmaktadır. Mikroyapısal analizler frit etkisinin Ag akım toplayıcı katmanını yoğunlaştırdığını göstermektedir. Ag yerine eklenen camsı faz Ag /LSF ince film katot arayüzey alanını azaltmakta ve yüksek ohmik dirence sebep olmaktadır. Camsı faz ayrıca LSF yüzeyini mühürlemekte, böylece yüksek polarizasyon dirençlerine yol açmaktadır. Simetrik yarı-hücreler üzerinde gerçekleştirilen elektrokimyasal empedans spektroskopisi ölçümleri frit içermeyen Ag mürekkepleri kullanıldığında itriya katkılı zirkonya elektrolitin özdirenci ile örtüşen ohmik dirençler ve kabul edilebilir katot polarizasyon dirençlerinin (örn., 700 ℃ ve durağan hava ortamında 0.5 Ωcm²) elde edilebildiğini göstermektedir. 

Keywords

• Katı Oksit Yakıt Hücreleri,Akım Toplayıcı,Gümüş,Empedans Spektroskopisi,Katot

EFFECT OF FRIT CONTENT IN THE SILVER CURRENT COLLECTOR INKS ON THE ELECTROCHEMICAL PERFORMANCE OF SOLID OXIDE FUEL CELL CATHODES

Abstract

Silver (Ag) inks are often used as precursors to form current collector layers on the intermediate-temperature solid oxide fuel cell (SOFC) cathodes. It has been common practice to add glassy phase (frit) particles into the Ag inks to achieve good adhesion between the current collector and the cathode layers upon firing. However, insufficient attention has been given to the effects of frit content on the microstructure and the current collecting properties of Ag layers. This study presents the effect of frit addition on the measured electrochemical performance of La_0.6Sr_0.4FeO₃ (LSF) thin film cathodes. Microstructural analyses reveal that frit addition significantly densifies the Ag current collector layer. The glassy phase replacing Ag reduces the contact area between the Ag particles and the LSF thin film cathode, resulting in increased ohmic resistances. The glassy phase also seals the electrocatalytic surface of the LSF thin film, thus enhancing the cathode polarization resistances. Electrochemical impedance spectroscopy measurements on symmetrical half-cells reveal that ohmic resistances matching the resistivity of the yttria stabilized zirconia electrolyte (YSZ) and acceptable cathode polarization resistances (e.g., 0.5 Ωcm² at 700℃ in air) can be obtained when frit-free Ag current collector inks are used. 

Keywords

• Solid Oxide Fuel Cells,Current Collectors,Silver,Impedance Spectroscopy,Cathode

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