Electrochemical Performance and Carbon Resistance Comparison between Tin, Copper and Silver-Doped Nickel/Yttria-Stabilized Zirconia Anodes SOFCs Operated with Biogas

Abstract

Traditional Ni/YSZ anode SOFCs were modified by Sn, Cu and Ag by an infiltration method to obtain Sn-Ni, Cu-Ni and Ag-Ni alloy anode catalysts on the anode. The obtained maximum power density of Ni/YSZ, Sn-doped Ni/YSZ, Cu-doped Ni/YSZ, and Ag-Ni/YSZ cells fuelled by simulated biogas (14 mL min −1 CH 4 , 7mL min −1 CO 2 and 7mL min −1 N 2 ) at 750°C were 0.101, 0.272, 0.085 and 0.102 W cm −2 respectively. Stability tests of SOFCs in biogas revealed that the stability of Sn-Ni/YSZ and Ag-Ni/YSZ cells in operation was greatly improved compared to the undoped Ni/YSZ cell. Both Sn-Ni/YSZ and Ag-Ni/YSZ cells stably operated for 48 h, but Ni/YSZ cell ceased operation after 19 h due to carbon deposition. The addition of small amount of Cu did not enhance the anti-coking ability. Other than with the severe carbon deposition on the Ni/YSZ anode surface, no observable fibrous carbon could be identified on the Sn-Ni/YSZ and Ag-Ni/YSZ anode surfaces.

Recent advances in carbon-resistant anodes for solid oxide fuel cells

“…Hence, the long-term stability of the SOFCs under biogas fuel could be significantly improved by adding 1 wt% Sn to the Ni/YSZ anode. 122…”

“…133 Jiang et al also found that doping the Ni–YSZ anode with 1 wt% Ag reduced the MPD of the cell when operating under the condition of 50% CH 4 –25% CO 2 –25% N 2 , but the long-term stability could be greatly improved. 122 Wu et al further improved the relevant works about introducing Ag in the Ni–YSZ anode by the electroless plating method, instead of using the impregnation method. Also, it was found that the MPD of the SOFCs with the Ni–Ag–YSZ anode increased whether in H 2 , dry CH 4 or dry C 2 H 6 fuel.…”

“…Hence, the long-term stability of the SOFCs under biogas fuel could be significantly improved by adding 1 wt% Sn to the Ni/ YSZ anode. 122 Singh et al prepared (1 wt%) Sn-Ni-YSZ anodes at a high sintering temperature (1450 1C) and evaluated their direct utilization of CH 4 at 800 1C. They found that Sn enhanced the shrinkage of the Ni-YSZ anode during the sintering stage of the preparation process, and this shrinkage matched better with the electrolyte shrinkage, which may help to reduce the stresses during the fabrication process.…”

A review on the preparation of anode materials and anode films for solid oxide fuel cell applications

“…Tape casting is a wet forming method that involves the mixing of slurry and additives with some lamination and sintering steps. [193][194][195][196] The thickness of the layers can be controlled by using a doctor blade and adjusting slurry viscosity. The resultant layer varies between 10 and 1000 μm.…”

Evaluating the drop of electrochemical performance of Ni/YSZ and Ni/ScSZ solid oxide fuel cells operated with dry biogas

“…22,36 Several anode modification strategies have been tested with methane as representative of hydrocarbon fuel such as using Ni-free copper-ceria-based anodes, 5,15,[42][43][44] perovskites-based anodes, [45][46][47] substitution of the ceramic oxides, 48,49 and anode surface modification. 38,[50][51][52][53] In spite of the carbon affinity to Ni, Ni is still preferred due to its higher electrical conductivity, superior catalytic activity and compatibility with other SOFC layers. 22 As Ni/ScSZ cells have the similar properties to Ni/YSZ cells, whilst ScSZ has higher ionic conductivity, research work comparing these two anode materials has been widely reported, including the implementation of biogas as fuel.…”