Effects of Manganese Oxides on the Activity and Stability of Ni-Ce0.8Sm0.2O1.9 Anode for Solid Oxide Fuel Cells with Methanol As the Fuel

Abstract

Solid oxide fuel cells (SOFCs) are one of the most promising devices for the direct conversion of chemical energy in fuels into electric power[1]. The Ni-based cermet has been considered as the most promising anode material for SOFCs due to its high catalytic activity, sufficient electrical conductivity and low cost[2]. However, Ni-based anodes face a severe problem of carbon deposition when fueled with hydrocarbons[2]. In this work, Ni-MnOx-Ce0.8Sm0.2O1.9 (SDC) is synthesized with a hydrothermal method and investigated as the anode material of an SOFC fed with methanol. The lowest anodic polarization resistance is obtained when the molar ratio of Mn to Ni is 0.05:0.95. The single cell with that anode and SDC-carbonate composite electrolyte exhibits a maximum power density of 722 mW cm-2 at 700 oC (Fig. 1). The high catalytic activity is attributed to the transfer of electrons from Ni to Mn and the increase of the content of the lattice oxygen in the anode. Mn also increases the resistance to carbon deposition of the anode due to the high lattice oxygen content and the redox cycle of the Mn species. The stability of the single cell is enhanced with the increase of the content of Mn in the anode. Fig.1 I–V and I-P curves of the fuel cells with various anodes at 700 °C with methanol as fuel. References A. Sin, E. Kopnin, Y. Dubitsky, et al., Journal of Power Sources, 2007, 164: 300–305.Z. Wang, W. Weng, K. Cheng, et al., Journal of Power Sources, 2008, 179: 541-546.S. Alayoglu, K. An, G. Melaet, et al., The Journal of Physical Chemistry C, 2013,117: 26608-26616. Figure 1