Compositional and microstructural effects in composite electrolytes for fuel cells

Abstract

Composite ionic conductors were produced by combination of alkaline carbonates with various ceramic oxides, including ceria, zirconia and alumina. The adopted mechano-thermal processing routes originated materials with the same nominal composition but with significantly different microstructures. The electrical performance of these composites, studied by impedance spectroscopy, showed the relevance of the mixed carbonate phase on the transport properties, but also unexpected composite effects. The role of grain size on the electrical performance could not be isolated from the possible influence of alkaline metal rich interfacial layers (ceramic/carbonate) consisting of nanosized 1D crystals. Modest electrode impedances in open air experiments are coherent with the coexistence of various charge carriers. The known interaction of major composite constituents and minor secondary phases with water might explain the presence of additional charge carriers.

Benchmarking the ambipolar conductivity of composite electrolytes for gas separation membranes

“…The green pellets were sintered at 690°C for 1 h. Detailed processing conditions were described elsewhere [28][29][30][31]. Composite powders were prepared by high energy milling, carried out in a planetary ball mill with Nylon containers and zirconia-based balls (balls to powder mass ratio of 10:1, respectively).…”

“…Following our own experience with these materials [28][29][30][31], Gd-doped ceria (CGO) was selected as oxide phase, while eutectic mixture of sodium and lithium carbonates (NLC) was used as second phase. Following our own experience with these materials [28][29][30][31], Gd-doped ceria (CGO) was selected as oxide phase, while eutectic mixture of sodium and lithium carbonates (NLC) was used as second phase.…”

Breakthrough fuel cell technology using ceria-based multi-functional nanocomposites

“…ceria-chloride [77,78], ceria-sulphate [63], ceria-hydrates [11,17] and most commonly ceria-carbonates [9][10][11][12][13][14][15][16]18,[53][54][55][56][57][58] have been studied. These are crystalline in ceria constituent phases, and the salts are amorphous.…”

The microstructure effect on ion conduction in composite electrolyte

“…Conductivity is not only related to material composition and temperature but also to material microstructure . Upon the same raw material, different electrolyte microstructure could be constructed via different preparation methods, which may lead to difference in electrolyte conductivity.…”

“…12 Conductivity is not only related to material composition and temperature but also to material microstructure. 14,15 Upon the same raw material, different electrolyte microstructure could be constructed via different preparation methods, which may lead to difference in electrolyte conductivity. For electrolytes made from the same material, the difference in electrolyte microstructure is mainly represented by different particle sizes.…”