Controlled electrolyte pre-nickelization boosts protonic ceramic fuel cell performance

Protonic ceramic fuel cells are efficient energy-conversion technology which typically employ a nickel-based anode substrate and a thin-film electrolyte to maximize power output at reduced temperatures. However, nickel contamination of the electrolyte by the anode during high-temperature co-sintering remains a long-standing challenge that may degrade ionic transport and cell stability. Here, we address this issue by strategically pre-incorporating a small amount of nickel into BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ perovskite lattice to offset undesired nickel diffusion from the anode via mutual diffusion, leading to a reduced sintering temperature and improved microstructural uniformity. This controlled pre-nickelizated Ba(Zr 0.1 Ce 0.7 Y 0.1 Yb 0.1 ) 0.97 Ni 0.03 O 3-δ achieves a high proton conductivity of 3.65 × 10 -2 S cm -1 at 700 °C in wet air, approximately twice that of BZCYYb. Annealing in reducing atmosphere further induces surface reconstruction and in-situ exsolution of Ni nanoparticles from Ba(Zr 0.1 Ce 0.7 Y 0.1 Yb 0.1 ) 0.97 Ni 0.03 O 3-δ , significantly improving charge transfer at the anode-electrolyte interface and facilitating proton incorporation. The resulting PCFCs deliver an impressive power density of 1500 mW cm -2 at 650 °C and maintain stable performance for 200 h. These results highlight the critical role of pre-nickelization and its concentration, demonstrating an effective strategy for mitigating electrolyte contamination and designing high-performance PCFCs.