Fe₂O₃ powder modified with Ce_0.6Mn_0.3Fe_0.1O₂ and Cr₂O₃ 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 H₂O/H₂redox mediator. The prepared Fe powder modified with both Cr₂O₃and Ce_0.6Mn_0.3Fe_0.1O₂ 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 H₂ flow so-called chemical charge, a discharge capacity of 900 mAh·g_-Fe⁻¹was 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.