Enhanced Performance of a Pr₄Ni₃O_10±δ–Ce_0.75Gd_0.1Pr_0.15O_2−δ Composite Electrode via Particle Size Grading

A particle grading strategy was applied in Pr₄Ni₃O_10±δ (PNO)–Ce_0.75Gd_0.1Pr_0.15O_2−δ (CGPO) composite electrodes for intermediate-temperature solid oxide fuel cells. By testing of ungraded and graded electrodes and analysis of the obtained impedance spectra with the help of the distribution of relaxation time, it was found that the increase in oxygen species diffusion resistance, due to greater tortuosity of electrode particles, can be suppressed by the grading strategy. At the same time, the step of charge transfer can be enhanced. Overall, graded electrodes have much lower area specific resistance (ASR) than ungraded electrodes. The lowest ASR obtained for graded electrodes is 0.059 Ω cm² at 625 °C (0.025 Ω cm² at 698 °C) and p_O2 of 0.21 atm, nearly a one-fold decrease compared to 0.11 Ω cm² for ungraded electrodes at the same condition.