Progress and Prospects in Symmetrical Solid Oxide Fuel Cells with Two Identical Electrodes

Abstract

The increasing impact of the greenhouse effect and environmental pollution from excessive and low-effi ciency use of everdiminishing fossil fuels has urged us to develop new energy materials and technologies for transitioning to a sustainable infrastructure. With this in mind, fuel cells, based on a concept Symmetrical solid oxide fuel cells (SOFCs) have attracted increasing attention due to their potential for improved thermomechanical compatibility of the electrolyte and the electrodes, reduced fabrication cost, and enhanced immunity to coking and sulfur poisoning. While the electrode materials of symmetrical SOFCs are initially limited to those with stable phase structures under both reducing and oxidizing atmospheres, many novel electrode materials are currently being developed and investigated that may undergo a benefi cial phase transition or reduction in a reducing atmosphere, although the same material may be used initially for the construction of both anode and cathode. Here, the advances made in the development of electrode materials and structures for symmetrical SOFCs are summarized, including single-phase electrodes, multi-phase (composite) electrodes, and those that are reducible upon exposure to a reducing atmosphere. The electrical conductivity, thermomechanical properties, and redox behavior of these electrode materials, together with their performance and stability in different SOFCs, are discussed and analyzed. The problems associated with different types of symmetrical SOFCs are outlined and the materials that show promise as symmetrical electrodes are highlighted, offering critical insights and useful guidelines for knowledge-based rational design of better electrodes for commercially viable symmetrical SOFCs.

A cobalt-free electrode material La0.5Sr0.5Fe0.8Cu0.2O3−δ for symmetrical solid oxide fuel cells

“…Limited materials have been reported to be effectively used as both anode and cathode for SSOFCs [7]. Conventional ceramic anode materials as electrodes for SSOFC showed poor cathode performance, and consequent low fuel cell output [4,[8][9][10][11],…”

Tuning layer-structured La0.6Sr1.4MnO4+δ into a promising electrode for intermediate-temperature symmetrical solid oxide fuel cells through surface modification

“…Recently, a new conguration of SOFCs, in which the same material is used for both electrodes, was proposed, and the corresponding fuel cells were called symmetrical SOFCs. [8][9][10][11][12][13][14][15][16] In fact, with low-temperature polymer-electrolyte-membrane fuel cells, the anode and cathode are oen fabricated from the same Pt/C-based catalyst, although they may contain different Pt contents. 17,18 The adoption of the same material composition for both electrodes in SOFCs can bring several benets, such as reduced fabrication cost and increased cell stability, as well as enabling facile cell regeneration.…”

“…17,18 The adoption of the same material composition for both electrodes in SOFCs can bring several benets, such as reduced fabrication cost and increased cell stability, as well as enabling facile cell regeneration. [8][9][10][11][12][13][14][15][16] Therefore, recently, an increased interest in the development of symmetrical SOFCs has been envisioned.…”

A perovskite oxide with high conductivities in both air and reducing atmosphere for use as electrode for solid oxide fuel cells

“…In a recent report, it was found that a much better stability can be achieved by SOFCs which operate in both SOFC and solid oxide electrolytic cell (SOEC) modes (reversible SOFC)2. For reversible SOFCs, the use of a symmetrical electrode such as (La 0.75 Sr 0.25 )Cr 0.5 Mn 0.5 O 3−δ (LSCM) would be an ideal solution345. An essential requirement of the electrode material is that it must exhibit a high conductivity in both air and fuel conditions at the fuel cell operating temperature.…”