A highly active and stable cobalt-free Iron-based perovskite cathode for solid oxide electrochemical cells

Area of Science:

• Materials Science
• Electrochemistry
• Energy Conversion and Storage

Background:

• Iron-based perovskite electrodes in solid oxide electrochemical cells (SOCs) suffer from limited activity and durability.
• Existing materials struggle to meet the demands for efficient energy conversion in fuel cells and electrolysis.

Purpose of the Study:

• To investigate Mn and P co-doped SrFe_0.9-xMn_0.1P_xO_3-δ (SF_0.9-xM_0.1P_x) as improved cathode materials for SOCs.
• To evaluate the impact of co-doping on electrochemical performance, oxygen vacancy generation, and oxygen adsorption/dissociation.
• To assess the suitability of these materials for both solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs).

Main Methods:

• Synthesis of Mn and P co-doped SrFeO_3-δ (SF) perovskite materials with varying P content (x = 0, 0.05, 0.10, 0.15).
• Systematic investigation of material properties and electrochemical performance at 800 °C.
• Fabrication and testing of SOFC and SOEC devices using the developed cathode materials.

Main Results:

• Co-doping effectively regulated grain size, promoted oxygen vacancy generation, and enhanced oxygen adsorption/dissociation in SF materials.
• The SFM_0.1P_0.1 cathode showed a 43.48% reduction in polarization resistance (R_p) to 0.078 Ω cm² and a 140.43% increase in output performance to 938.02 mW cm^-2 at 800 °C.
• SOEC cells with SFM_0.1P_0.1 achieved a current density of 1.73 A cm^-2 at 800 °C and 1.5 V for CO₂ electrolysis, with excellent stability demonstrated for both SOFC and SOEC operations.

Conclusions:

• Mn and P co-doping is a highly effective strategy for enhancing the activity and durability of iron-based perovskite cathodes in SOCs.
• The developed SFM_0.1P_0.1 material shows significant promise as a high-performance cathode for both SOFC and SOEC applications.
• Co-doping with both metal and non-metal cations offers a viable pathway for advancing electrode performance in electrochemical energy systems.