Engineering Synergistic Oxygen-Proton Properties for High-Performance Reversible Protonic Ceramic Cell Air Electrodes

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Reversible protonic ceramic cells (RePCCs) are crucial for integrating renewable energy sources.
• RePCC performance is critically dependent on the air electrode's ability to transport protons, oxygen, and electrons.
• A fundamental trade-off exists in air electrodes where oxygen exchange requires vacancies, but hydration consumes them.

Purpose of the Study:

• To investigate the impact of material design on oxygen and proton transport in RePCC air electrodes.
• To demonstrate the importance of balancing oxygen and proton transport properties for high-performance RePCCs.
• To explore Nb doping in Sr3Fe2O7-δ as a strategy to optimize air electrode function.

Main Methods:

• Utilized a niobium (Nb)-doped Sr3Fe2O7-δ (SF) perovskite system.
• Investigated the effect of Nb doping on oxygen vacancy concentration and hydration levels.
• Analyzed the resulting Sr3Fe1.9Nb0.1O7-δ (SFNb0.1) electrode's transport properties and crystal structure stability.

Main Results:

• Excessive hydration in undoped SF limits oxygen-ion transport and electrocatalytic activity.
• Nb doping in SFNb0.1 maintains oxygen vacancy concentration while suppressing excessive hydration.
• The SFNb0.1 electrode demonstrated a balanced proton and oxygen transport, enhanced activity, and improved structural stability.

Conclusions:

• Balanced oxygen-proton transport is a critical design principle for high-performance RePCC air electrodes.
• Nb doping in Sr3Fe2O7-δ effectively optimizes air electrode performance by managing hydration and oxygen vacancies.
• This study provides a pathway for developing more efficient and stable RePCCs for sustainable energy applications.