Electrochemical Characterization Of SOFC Cathode Material La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ Nanofiber Prepared By Electrospinning

Nowadays, IT-SOFC(intermediate temperature solid oxide fuel cell) is a hot research. The performance loss of IT-SOFC is mainly caused by the polarization of cathode. Therefore, reducing the polarization of cathode is the key to develop IT-SOFC. Perovskite La0.6Sr0.4Co0.2Fe0.803.8(LSCF) are promising cathode materials for IT-SOFC due to excellent electronic and ionic conductivity, low coefficient of thermal expansion and superior electrochemical catalytic activity. The cathode structure is also crucial to the performance of cathode. The cathode with nanofiber network structure which has continuous path for conducting ion and electron, excellent electrochemical catalytic activity, and high percolation can greatly enhance the cathode performance.Electrospinning is a simple method for preparing nanofiber. La0.6Sr0.4Co0.2Fe0.803-δ(LSCF) nanofibers were prepared by electrospinning and the electrochemical characterization of the cathode with nanofiber network structure was investigated in this paper.The electrospinning parameters of PVP content, voltage, curing distance and feed rate were studied. The optimized parameters were as follow:PVP content2.5～2.9wt%, voltage12-16kV, curing distance11-15cm, feed rate0.5-0.7ml/h.The phase, element, microstructure of LSCF nanofibers were characterized by TG-DTA, XRD, SEM, EDS, TEM, respectively. A containing La, Sr, Co, Fe and O elements, diameter of130nm and length distribution of3-20μm perovskite LSCF nanofiber were obtained calcined at800℃.The LSCF nanofiber network structure cathode fabricated by electrospinning possessed outstanding electrochemical characterization. Polarization resistance of LSCF nanofiber network structure cathode were0.746Ω·cm2,0.517Ω·cm2,0.206Ω·cm2and0.106Ω·cm2at600℃,650℃,700℃and750℃, respectively. Using hydrogen as fuel and air as oxidant, the maximum power density of single cell(Ni+GDC||GDC||LSCF) with the LSCF nanofiber structure cathode were0.76W·cm-2and1.04W·cm-2, at650℃and700℃, respectively; while the maximum power density of single cell (Ni+GDC||GDC||LSCF) with LSCF nanofiber compounding20wt%GDC as cathode were0.88W·cm-2and1.2W·cm-2at650℃and700℃, respectively.