Two birds with one stone: Benefits of sintering additives on sinterability and electrical property of new protonic ceramic fuel cell electrolyte SrSn_0.8Sc_0.2O_3-δ

Various approaches have been developed to address the challenges of difficult densification in traditional BaZrO₃-based and BaCeO₃-based protonic ceramic fuel cells (PCFCs) electrolytes. The addition of sintering additives, the most widely used approach, has been found to potentially compromise electrical performance while improving sinterability in traditional sintering. Recently, SrSn_0.8Sc_0.2O_3-δ (SSS) has emerged as a promising proton-conductor material; however, there is still space for improvement in its electrical and sintering properties. In this study, a systematic investigation was conducted into the effect of sintering additives (NiO, ZnO, CuO) on the electrical performance of the new proton conductor SSS. Notably, SSS-1wt%NiO was found to decrease the sintering temperature from 1600 °C to 1400 °C (reaching 92 % relative density) and increase protonic conductivity from 2.61 × 10⁻³ S cm⁻¹ to 3.06 × 10⁻³ S cm⁻¹ at 600 °C, without any increase in electronic conductivity. This demonstrates a synergistic beneficial effect on both sinterability and electrical properties. Furthermore, the Ni-SSS|SSS-1wt%NiO|SSS-BCFZY single cell achieved the highest peak power density (528.5 mW cm⁻² at 800 °C), surpassing all the other SSS-based single cells. Therefore, the addition of NiO to the SSS electrolyte demonstrates the significant sintering and electrical properties of SSS, proving evidence for the potential commercial application of SSS electrolytes for PCFCs.