High-Performance Protonic Ceramic Fuel Cell Cathode using Protophilic Mixed Ion and Electron Conducting Material

Protonic ceramic fuel cells (PCFCs) are attractive energy conversion devices for intermediate-temperature operation (400-600 °C), however widespread application of PCFCs relies on the development of new high-performance electrode materials. Here...

Electrochemical Evaluation of Layered Perovskite YBa0.5Sr0.5Co1.5Fe0.5O5+δ Cathode as a Triple Ionic and Electronic Conductor for Protonic Ceramic Fuel Cells

Protonic ceramic fuel cells (PCFCs) have receiving huge attention as a promising energy conversion device because of their high conversion efficiency, lack of fuel dilution, and high ionic conductivity at intermediate temperature regime (400 ∼ 600 oC). Although this fuel cell system can effectively solve the main obstacle for the commercialization of conventional solid oxide fuel cells, electrochemical performance is currently limited by the cathodic polarization due to insufficient catalytic activity. To overcome this issue, layered perovskite materials, PrBa0.5Sr0.5Co1.5Fe0.5O5+δ, have been discovered as triple ionic and electronic conductor, which enables to simultaneously conduct H+/O2-/e-. Despite great advantages, there is large gap in the thermal expansion coefficient (TEC) between the cathode and electrolyte. Herein, we developed a new triple conducting cathode material, YBa0.5Sr0.5Co1.5Fe0.5O5+δ (YBSCF) to minimize TEC while maintaining the high electro-catalytic activity with excellent hydration properties. Structural analysis, hydration properties, and electrochemical performances of YBSCF cathode were investigated. In particular, the peak power density of YBSCF cathode based on BaZr0.4Ce0.4Y0.1Yb0.1O3-δ (BZCYYb4411) electrolyte attained 0.702 W cm-2 at 600 oC. Moreover, power output is fairly stable for 300 h without observable degradation by applying a constant voltage of 0.7 V at 600 oC.

Development of Ammonia Fueled Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) can generate electricity through an electrochemical conversion of the chemical energy of fuels including hydrogen, hydrocarbons, and biogas because of high operation temperatures. Ammonia has recently been considered as a promising hydrogen carrier that is relatively convenient to store and transport and can be decomposed into hydrogen and nitrogen with no carbon emission via catalytic cracking. Thus, much effort has been made to utilize ammonia as a clean fuel to SOFCs for power generation at high efficiency. This review is aiming at delivering the current progress of developing high temperature ceramic fuel cells fed with ammonia, particularly more focused on the achievements of a direct ammonia fueled SOFC (DA-SOFC) to shed light on the challenges of degrading the performance and durability. The problems are primarily attributed to a lack of rational catalysts, thermal imbalance, and the evolution of nitrides on the components including the Ni based anode, Ni mesh as current collector, and stainless steels of metallic interconnect that are exposed to the ammonia fuel environment incurring microstructural deformations and electrical and electrochemical deteriorations. Lastly, strategic pathways to overcome the inadequate performance and the instability are suggested to accomplish a commercialization of DA-SOFCs.