Critical Role of In-Situ-Generated Eutectic Carbonates in Superstructured Solid Fuel Cells

Area of Science:

• Materials Science
• Electrochemistry
• Energy Conversion

Background:

• Carbonate-superstructured solid fuel cells (CSSFCs) offer excellent performance, low cost, and ease of fabrication.
• Optimizing ionic conductivity in solid electrolytes is crucial for enhancing fuel cell efficiency.

Purpose of the Study:

• To demonstrate the critical role of in-situ generated eutectic carbonate phase in CSSFC performance.
• To investigate the impact of eutectic Li2CO3/Na2CO3 on the ionic conductivity of Ce0.8Sm0.2O1.9 solid electrolyte.
• To evaluate the resulting enhancement in CSSFC power density using methane fuel.

Main Methods:

• Fabrication of CSSFCs with a Ce0.8Sm0.2O1.9 solid electrolyte.
• In-situ generation of a eutectic Li2CO3/Na2CO3 phase within the CSSFC structure.
• Measurement of oxygen ionic conductivity of the modified solid electrolyte.
• Performance testing of CSSFCs using methane fuel at 550 °C to determine peak power density.

Main Results:

• The in-situ generated eutectic carbonate phase increased the oxygen ionic conductivity of Ce0.8Sm0.2O1.9 by 20 times (from 3.5 × 10^-3 to 7.3 × 10^-2 S cm^-1).
• This significant improvement in ionic conductivity led to a 6-fold enhancement in CSSFC peak power density, reaching up to 206 mW cm^-2 with methane fuel at 550 °C.

Conclusions:

• The in-situ generation of a eutectic carbonate phase is a key factor for achieving high performance in CSSFCs.
• This finding provides a critical pathway for designing more efficient and cost-effective CSSFCs for clean energy applications.
• The enhanced ionic conductivity of the solid electrolyte directly translates to improved fuel cell power output.