A review on phosphate based, solid state, protonic conductors for intermediate temperature fuel cells.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Conversion

Background:

• Proton exchange membrane fuel cells (PEMFCs) use polymer electrolytes (e.g., Nafion), limiting operation to ~80°C.
• Solid oxide fuel cells (SOFCs) operate at high temperatures (~1000°C) using oxide electrolytes (e.g., YSZ, GDC).
• An unexplored intermediate temperature regime (~300°C) offers potential for novel fuel cell systems.

Purpose of the Study:

• To review the potential of phosphate compounds as electrolytes for intermediate-temperature fuel cells.
• To highlight the advantages of phosphate-based electrolytes for fuel cell applications.

Main Methods:

• Literature review summarizing existing research on phosphate electrolytes.
• Discussion of various phosphate compounds including ammonium polyphosphate, pyrophosphate, and cesium phosphate.
• Analysis of preparation methods, conduction mechanisms, and conductivity values of these electrolytes.

Main Results:

• Phosphate compounds demonstrate potential as electrolytes for fuel cells operating at intermediate temperatures (around 300°C).
• Various phosphate-based materials exhibit suitable properties for this temperature range.
• Preparation methods and conduction mechanisms are detailed for different phosphate electrolytes.

Conclusions:

• Phosphate compounds represent a promising class of materials for intermediate-temperature fuel cell electrolytes.
• Further exploration of phosphate electrolytes can lead to advancements in fuel cell technology.
• These electrolytes offer a viable alternative to current technologies for a new operational regime.