Recent Progress in the Design, Characterisation and Application of LaAlO3- and LaGaO3-Based Solid Oxide Fuel Cell Electrolytes

Abstract

Solid oxide fuel cells (SOFCs) are efficient electrochemical devices that allow for the direct conversion of fuels (their chemical energy) into electricity. Although conventional SOFCs based on YSZ electrolytes are widely used from laboratory to commercial scales, the development of alternative ion-conducting electrolytes is of great importance for improving SOFC performance at reduced operation temperatures. The review summarizes the basic information on two representative families of oxygen-conducting electrolytes: doped lanthanum aluminates (LaAlO3) and lanthanum gallates (LaGaO3). Their preparation features, chemical stability, thermal behaviour and transport properties are thoroughly analyzed in terms of their connection with the target functional parameters of related SOFCs. The data presented here will serve as a starting point for further studies of La-based perovskites, including in the fields of solid state ionics, electrochemistry and applied energy.

La-Doped Alumina, Lanthanum Aluminate, Lanthanum Hexaaluminate, and Related Compounds: A Review Covering Synthesis, Structure, and Practical Importance

“…At large, perovskites are of great technological importance as multilayer capacitors, piezoelectric transducers, thermistors, switches, actuators, superconductors and ferromagnets. , Perovskites are also considered to be promising electrolytes and electrode materials (e.g., for solid-oxide fuel cells). − Another application is the preparation of films and membranes (e.g., for air separation or catalytic membrane reactors). − See Table for useful properties of selected perovskites. The application in thermal barrier coatings was also considered, whereby layered perovskites of so-called Ruddlesden–Popper structure have an exceptional low thermal conductivity .…”

Recent advances in electrophoretic deposition of thin-film electrolytes for intermediate-temperature solid oxide fuel cells

“…Scdoped ZrO2, co-doped with other rare-earth elements to improve phase stability at decreased temperatures, also give advantages compared to YSZ when using in IT-SOFC [156]. The promising electrolyte candidate for the devices operating in the IT range -solid state electrolytes with a perovskite structure based on LaGaO3 and LaAlO3 substituted on the A-and B-sites with enhanced oxygen ionic conductivity [9]. Other ionic-conducting oxides with an apatite structure based on La10Si6O26 composition also can of interest from the point of view of low-cost, high abundance materials [157].…”

“…As in the case of YSZ, CeO2-based barrier layers are often used to prevent interaction LGSM electrolyte with perovskite cathodes and cermet anodes [9]. A three-layer GDC/La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM8282)/GDC electrolyte was obtained by Suzuki et al [133] with a layer thickness of ~15 µm on a porous NiO-YSZ anode substrate using a conductive polypyrrole sublayer.…”

“…La-doped CeO2 was found to be more compatible with LGSM electrolytes [9]. Bozza et al [166] carried out one-step EPD of a LSGM8282 electrolyte on tape-cast composite electrodes, composed of La-doped ceria (LDC), polyvinylidene difluoride (PVDF) and carbon powders.…”

“…The main obstacle standing in the way of the realization of the reduced-temperature approach is a high ohmic resistance of the supporting electrolyte membrane. Thus, Yttria-stabilized Zirconia (YSZ) electrolyte traditionally used in hightemperature SOFCs was replaced by new materials possessing superior conductivity in IT range: oxygen-ion conducting electrolytes based on Scandia-stabilized Zirconia (SSZ) [8], Sr, Mg-doped Lanthanum Gallate (LSGM) [9,10], doped Ceria [11-13], as well as highlyeffective proton conducting electrolytes, particularly, based on Barium cerates/zirconates BaCe(Zr)O3 [14 -16]. Another effective way to reduce ohmic resistance of a solid-state electrolyte is to reduce its thickness.…”