Evaluation of ((La0.60Sr0.40)0.95Co0.20Fe0.80O3-x)-Ag Composite Anode for Direct Ammonia Solid Oxide Fuel Cells and Effect of Pd Impregnation on the Electrochemical Performance

Abstract

Ammonia produced using renewable hydrogen is being viewed as a promising media for the export of energy from locations rich in renewable energy sources. Solid oxide fuel cells (SOFCs) are efficient devices for converting such exported ammonia back into electricity at the point of use; however, investigations on materials and operating regimes for direct ammonia fuelled SOFCs are limited. In this work, we evaluated the direct ammonia SOFC performance with a Silver-Lanthanum Strontium Cobalt Ferrite (Ag-LSCF) composite anode and a novel Palladium (Pd) nanoparticle decorated Silver-Lanthanum Strontium Cobalt Ferrite (Pd-Ag-LSCF) composite anode in the temperature range of 500 °C to 800 °C. It is hypothesised that palladium nanoparticles in the anode provide hydrogen dissolution and shift the ammonia decomposition reaction towards the right. The cell performance was evaluated with both hydrogen and ammonia as fuels and a clear-cut improvement in the performance was observed with the addition of Pd for both the fuels. The results showed performance enhancements of 20% and 43% with hydrogen and ammonia fuels, respectively, from the addition of Pd to the Ag-LSCF anode. Open-circuit voltage (OCV) values of the cells with hydrogen and ammonia fuels recorded over the temperature range of 500 °C to 800 °C indicated the possibility of direct electro-oxidation of ammonia in SOFCs.

Challenges and advancement in direct ammonia solid oxide fuel cells: a review

“…Our group also recently reported the feasibility of a DASOFC for power generation employing a 3YSZ electrolyte-supported Pd-Ag-LSCF symmetric cell and achieved a power density of 73 mW cm −2 at 800 °C with ammonia fuel. 23 The low power density is due to poor electrolyte-supported cell structure, such as the thick 3YSZ electrolyte (∼300 μm), and the lower catalysis activity of the electrode materials. Recently, Cavazzani et al 85 posed to Pr 2 O 3 nanoparticles and Pr 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ , accompanied by the exsolution of CoFeRu-based alloy nanoparticles that improved the catalytic activity, anti-sintering capability, and stability of the anode.…”

“…Over the past few years, perovskites, double perovskites, spinel oxides, and pyrochlore oxides have also been widely studied as prospective DASOFC anode materials. Rathore et al 84 evaluated a Pd nanoparticle-infiltrated Ag-LSCF composite anode at 800 °C and reported a 43% performance improvement compared with bare Ag-LSCF. The authors concluded that Pd nanoparticles in the anode provided hydrogen dissolution that shifted the ammonia decomposition reaction forward, thus improving the overall cell kinetics.…”

“…Our group also recently reported the feasibility of a DASOFC for power generation employing a 3YSZ electrolyte-supported Pd–Ag-LSCF symmetric cell and achieved a power density of 73 mW cm −2 at 800 °C with ammonia fuel. 23 The low power density is due to poor electrolyte-supported cell structure, such as the thick 3YSZ electrolyte (∼300 μm), and the lower catalysis activity of the electrode materials. Recently, Cavazzani et al 85 studied a composite of 8YSZ and Ni-doped La 0.45 Sr 0.45 TiO 3 synthesized via sol–gel technique as a DASOFC anode at 780 °C in 40%NH 3 /60%Ar and achieved a peak power density of 3.7 mW cm −2 .…”

“…This is a more attractive option for "single-step ammonia to electricity" generation because of its capability of in situ ammonia cracking/decomposition and fuel cell operation ( power generation), which can offer high efficiencies for future combined heat and electricity production and transportation. 23 As ammonia cracking/decomposition is an endothermic reaction, ΔH = +45 kJ per mole, the high-temperature operation of SOFC and the heat generated within the SOFC cells (due to resistive losses) can assist this process. Also, the zirconia-based solid electrolyte is stable, and SOFCs have better compatibility with ammonia fuel.…”

“…Therefore, direct ammonia-fuelled SOFC (DASOFC) has the potential and can provide a pathway to decarbonize various applications reliant on fossil fuels. 23–25…”