Evaluation of a Metal Supported Ni-YSZ / YSZ / La2NiO4 IT-SOFC Elaborated by Physical Surface Deposition Processes

The elaboration of the last generation of metal supported IT-SOFCs by physical surface deposition processes is really challenging. Atmospheric Plasma Spraying (APS) process appears to be well adapted to build the porous anode layer [1] whereas Reactive Magnetron Sputtering (RMS) technique is suitable to deposit thin and dense layer. In the present work, we have deposited a Ni-YSZ anode by APS on porous metallic supports (ITM) produced by PLANSEE SE. Then, a thin YSZ electrolyte film was applied by RMS. Details about the elaboration of the half cell could be found in a previous work [2]. Various strategies have been followed to deposit the cathode layer on top of the previously deposited anode and electrolyte coatings. The Mixed Ionic and Electronic Conductor K₂NiF₄ structured material presents interesting electrocatalytic properties [3] allowing its utilization as cathode layer. Recent studies deal with the use of thin layers as cathodes in IT-SOFCs [4]. Therefore, RMS process was also evaluated to deposit a thin La₂NiO₄ layer (LNO) according to already optimized operating conditions [5]. In order to compare the efficiency of this dense layer as an individual cathode or a bonding cathode layer, the complete IT-SOFC building was elaborated by replacing and/or adding a screen-printed La₂NiO₄ coating (SP LNO). This layer was developed and optimized in ICMCB laboratory and has shown interesting performances in LNO/GDC/LNO half cells [6].

GDC diffusion barrier layers were deposited by RMS in order to limit the deleterious interaction between active layers in use.

Different cells with RMS LNO, SP LNO, and RMS LNO + SP LNO were produced and tested in a complete cell bench at 973 K. Impedance Spectroscopy and Voltametry measurements were performed on these samples to assess their electrochemical characteristics and performances.

The electrochemical resistances of these cells are too high and their performances are still lower than the literature ones. Analyses of the samples after the electrochemical tests permit to identify the density of the RMS LNO layer as the limiting factor lowering the cathodic electrochemical reaction. The sintering step performed on complete cells with SP LNO deteriorates the layers deposited by RMS as well as the metallic support explaining these performances. Nevertheless, using LNO bonding layer manufactured by RMS seems to be an interesting way to improve the polarization resistance of the cell.

References

[1] D. Stöver, D. Hatiramani, R. Vaβen, R. Damani, Surface and Coatings Technology 201 (2006) 2002-2005.

[2] J. Fondard, P. Bertrand, A. Billard, S. Skrabs, Th. Franco, G. Bertrand, P. Briois, Electrochemical Society Transactions 57 (2013) 673-682.

[3] E. Boehm, J.-M.Bassat, P.Dordor, F. Mauvy, J-C.Grenier, Ph. Stevens, Solid State Ionics 176 (2005) 2717 – 2725.

[4] I. Garbayo, V; Esposito, S. Sanna, A. Morata, D. Pla, L. Fonseca, N. Sabaté, A. Taracon, Journal of Power Sources 248 (2014) 1042-1049.

[5] J. Fondard, A. Billard, G. Bertrand, P. Briois, Solid State Ionics 265 (2014) 73-79.

[6] B. Philippeau, F. Mauvy, C. Mazataud, S. Fourcade, J-C. Grenier, Solid State Ionics 249-250 (2013) 17-25.