Lowering the Temperature of Solid Oxide Fuel Cells

TLDR

Fuel cells can surpass combustion limits, yet the focus on PEM fuel cells for the hydrogen economy has sidelined them, while solid oxide fuel cells can use conventional fuels but are hampered by high operating temperatures (~800 °C) that impose material, cost, and operational challenges. This work aims to enable solid oxide fuel cells to operate at much lower temperatures (~350 °C) by developing high‑conductivity electrolytes and nanostructured electrode designs, thereby transforming energy conversion and storage. The approach employs high‑conductivity electrolytes coupled with nanostructured electrodes to reduce the required operating temperature. Recent experiments show solid oxide fuel cells achieving about 2 W cm⁻² at 650 °C with flexible fueling, improving efficiency within existing fuel infrastructure.

Abstract

Fuel cells are uniquely capable of overcoming combustion efficiency limitations (e.g., the Carnot cycle). However, the linking of fuel cells (an energy conversion device) and hydrogen (an energy carrier) has emphasized investment in proton-exchange membrane fuel cells as part of a larger hydrogen economy and thus relegated fuel cells to a future technology. In contrast, solid oxide fuel cells are capable of operating on conventional fuels (as well as hydrogen) today. The main issue for solid oxide fuel cells is high operating temperature (about 800°C) and the resulting materials and cost limitations and operating complexities (e.g., thermal cycling). Recent solid oxide fuel cells results have demonstrated extremely high power densities of about 2 watts per square centimeter at 650°C along with flexible fueling, thus enabling higher efficiency within the current fuel infrastructure. Newly developed, high-conductivity electrolytes and nanostructured electrode designs provide a path for further performance improvement at much lower temperatures, down to ~350°C, thus providing opportunity to transform the way we convert and store energy.