Enhancing Ni anode performance via Gd2O3 addition in molten carbonate-type direct carbon fuel cell

•The effect of Gd2O3 addition to Ni anode in MC-type DCFC was investigated.•The performance of Ni/Gd2O3 anode was about 2 times higher than solely Ni anode.•The optimal ratio of Ni:Gd2O3 was 1:5.

Recently, there is a consensus that a limited performance in direct carbon fuel cell (DCFC) using molten carbonate electrolyte is caused by the limited triple phase boundaries (TPB) formation. In order to solve this problem, we added Gd2O3, a well-known lanthanide oxide material for the improvement of wettability in the Ni anode. As a result, it was clearly shown that the voltage drop level and charge transfer resistance was decreased, and therefore the peak power density was increased by almost two times that of solely Ni anode to reach up to 106.7 mW/cm2 with carbon black and 114.1 mW/cm2 with actual coal fuel. The increased wettability led to the improvement of triple phase boundary (TPB) formation and consequently the enhancement of DCFC performance. While the wettability was increased with oxide content in Ni anode, the proportion of Ni at the surface of anode and the electronic conductivity was gradually decreased. With this reason, the peak power density showed the volcano type change with the amount of Gd2O3 addition. Finally, it was revealed that the optimum composition for the anode was Ni:Gd2O3 = 1:5 in weight ratio.