Review: recent progress in low-temperature proton-conducting ceramics

Abstract

Proton-conducting ceramics (PCCs) are of considerable interest for use in energy conversion and storage applications, electrochemical sensors, and separation membranes. PCCs that combine performance, efficiency, stability, and an ability to operate at low temperatures are particularly attractive. This review summarizes the recent progress made in the development of low-temperature protonconducting ceramics (LT-PCCs), which are defined as operating in the temperature range of 25-400°C. The structure of these ceramic materials, the characteristics of proton transport mechanisms, and the potential applications for LT-PCCs will be summarized with an emphasis on protonic conduction occurring at interfaces. Three temperature zones are defined in the LT-PCC operating regime based on the predominant proton transfer mechanism occurring in each zone. The variation in material properties, such as crystal structure, conductivity, microstructure, fabrication methods required to achieve the requisite grain size distribution, along with typical strategies pursued to enhance the proton conduction, is addressed. Finally, a perspective regarding applications of these materials to low-temperature solid oxide fuel cells, hydrogen separation membranes, and emerging areas in the nuclear industry including off-gas capture and isotopic separations is presented.

Understanding the effect of water transport on the thermal expansion properties of the perovskites BaFe0.6Co0.3Nb0.1O3−δ and BaCo0.7Yb0.2Bi0.1O3−δ

“…Despite recent progress, the understanding of the interaction of the transition metal-containing perovskite electrodes with moisture, and their phase stability (at SOC conditions) is lacking. This is especially important with the increase in the application of protonconducting SOCs, where the moisture content at the air electrode can be much higher than 4% [42] -1 , but the very high oxygen transport properties with D chem value of 4.51 9 10 -5 cm 2 s -1 at 650°C make it a very interesting candidate for a SOC electrode [43]. BFCN requires Nb doping above y = 0.08 for pure cubic structure, while below that value it shows mixed cubic/hexagonal structure [44].…”

Effect of doping on the local structure of new block‐layered proton conductors based on BaLaInO4

“…Medium temperature (300–700°C) protonic conductors represent widely investigates class of materials due to their possible using as the electrolyte in the solid oxide fuel cell. [ 1–6 ] Most of these conductors are characterized by perovskite or perovskite‐related structure. [ 7 ] The possibility of proton transport in these phases is provided by the presence of oxygen vacancies in their structure.…”

One-Step Fabrication of Protonic Ceramic Fuel Cells Using a Convenient Tape Calendering Method

“…Protonic ceramic fuel cells (PCFCs) form a class of fuel cells (FCs) providing highly efficient and economically advantageous chemical-to-electrical energy conversion at elevated temperatures [1][2][3][4][5]. A proton-conducting electrolyte membrane as a PCFC's heart transports proton charge carriers with high levels of ionic conductivity compared with those of oxygen-ionic electrolytes of the traditional solid oxide fuel cells (SOFCs), owing to the corresponding high mobility/concentration of protons [6][7][8][9].…”