Fe 2 O 3 powder modified with Ce 0.6 Mn 0.3 Fe 0.1 O 2 and Cr 2 O 3 prepared by spray pyrolysis method for rechargeable Fe–air cell

Highly porous and uniform sphere shape Fe powder with a nano‐porous structure can be prepared successfully with a spray pyrolysis method and applied for solid oxide Fe–air rechargeable battery, which is consisted of solid oxide reversible cells using an H 2 O/H 2 redox mediator. The prepared Fe powder modified with both Cr 2 O 3 and Ce 0.6 Mn 0.3 Fe 0.1 O 2 shows a high redox reaction rate as well as cycle stability by uniform distribution. A discharge capacity of 1100 mAh·g ‐ Fe −1 with almost 100% coulombic efficiency was achieved at initial cycles and that larger than 800 mAh·g ‐ Fe −1 was sustained over 20 cycles at 873 K. After the reduction of Fe powder with H 2 flow so‐called chemical charge, a discharge capacity of 900 mAh·g ‐ Fe −1 was recovered and stably sustained for the following 20 cycles (40 total cycles), and discharge capacity may be sustained further longer cycles at 823 K. The round‐trip efficiency for charge and discharge was about 90%, which can be assigned to the high reversibility of Fe redox with nano‐porous structure prepared by spray pyrolysis method.