A composite oxygen electrode with high oxygen reduction and evolution activities for reversible solid oxide cells

Abstract

Reversible solid oxide cells (RSOCs) are highly efficient energy conversion devices for electricity generation and hydrogen production. However, their commercialization is significantly hindered by the slow oxygen reduction/evolution reaction (ORR/OER) activity of oxygen electrodes and the insufficient durability of the RSOCs. Herein, an active and durable PrBa_0.8Ca_0.2Co_1.5Fe_0.5O_5+δ–Ce_0.8Gd_0.2O_2-δ (PBCCF–GDC) composite oxygen electrode with mediate thermal expansion is developed, achieving a low polarization resistance of 0.058 Ω cm² at 750 °C. The PBCCF–GDC oxygen electrode has been applied and evaluated in both the button cell (Φ = 20 mm) and large-area cell (10 × 10 cm²), respectively. When utilized as an oxygen electrode in button cell, it achieves a peak power density of 0.88 W cm⁻² in the fuel cell (FC) mode, and a current density of −1.51 A cm⁻² at 1.3 V with 70% H₂O in the electrolysis cell (EC) mode at 750 °C, and favorable stability in the both FC and EC modes. When utilized in large-area cell, it exhibits a power of 29.5 W and good stability over 330 h, and an impressive electrolysis current of −27A at 1.3 V with 70% H₂O at 750 °C. The results indicate that PBCCF–GDC is a promising oxygen electrode material for RSOCs.