Fast ionic conduction in semiconductor CeO2-δ electrolyte fuel cells

Abstract

Producing electrolytes with high ionic conductivity has been a critical challenge in the progressive development of solid oxide fuel cells (SOFCs) for practical applications. The conventional methodology uses the ion doping method to develop electrolyte materials, e.g., samarium-doped ceria (SDC) and yttrium-stabilized zirconia (YSZ), but challenges remain. In the present work, we introduce a logical design of non-stoichiometric CeO 2-δ based on non-doped ceria with a focus on the surface properties of the particles. The CeO 2−δ reached an ionic conductivity of 0.1 S/cm and was used as the electrolyte in a fuel cell, resulting in a remarkable power output of 660 mW/cm 2 at 550°C. Scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS) clearly clarified that a surface buried layer on the order of a few nanometers was composed of Ce 3+ on ceria particles to form a CeO 2−δ @CeO 2 core-shell heterostructure. The oxygen deficient layer on the surface provided ionic transport pathways. Simultaneously, band energy alignment is proposed to address the short circuiting issue. This work provides a simple and feasible methodology beyond common structural (bulk) doping to produce sufficient ionic conductivity. This work also demonstrates a new approach to progress from material fundamentals to an advanced lowtemperature SOFC technology.

Improving Grain Boundary Conductivity of Ce0.9Gd0.1O2 − δ Electrolyte through Compositing with Carbonate or Semiconductor

“…Therefore, the electrical performance of low temperature SOFC can output stably without shorting circuit. [42,43]…”

A membraneless microfluidic fuel cell with a hollow flow channel and porous flow‐through electrodes

“…A variety of fuel cells are being developed to convert chemical energy into electrical energy. [1][2][3][4][5][6][7][8][9] Fuel cells have no emissions, better energy density, 10 and could supply power in applications ranging from miniature electronic devices to big plants. Most fuel cells use a proton exchange membrane (PEM) to carry out the electrochemical reactions.…”

“…Numerous MMFCs have been developed with different fuel-oxidant combinations, microchannel configurations, and electrode materials. [2][3][4][5][6][7][8][9] Multiple studies have been carried out to improve an MMFC's fuel utilization, crossover issues, mass-transport and Ohmic losses, and lower volumetric power density, which are considered as main setbacks. [27][28][29][30] Lower fuel utilization in MMFCs is caused by slow reaction rates at the cathode, including slow oxygen reduction, different fuel-oxidant kinetic properties, and triple phase solid-liquid-gas interactions, which are common conditions on the cathode side.…”

“…A variety of fuel cells are being developed to convert chemical energy into electrical energy 1‐9 . Fuel cells have no emissions, better energy density, 10 and could supply power in applications ranging from miniature electronic devices to big plants.…”

“…Kjeang et al 27 comprehensively reviewed the operation and applications of MMFCs. Numerous MMFCs have been developed with different fuel‐oxidant combinations, microchannel configurations, and electrode materials 2‐9 . Multiple studies have been carried out to improve an MMFC's fuel utilization, crossover issues, mass‐transport and Ohmic losses, and lower volumetric power density, which are considered as main setbacks 27‐30 .…”