LA-ICP-MS and EDS characterization of electrode/electrolyte interfaces in IT-SOFCs materials

Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) in combination with SEM is used for the determination of elemental spatial distribution in ceramic multi-layer systems as those found in Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs). Because layer sintering occurs at high temperature (usually well over 1000°C), there may be mutual diffusion of ions from one layer to the other, with dramatic consequences on cell performances. In this work, two model materials have been used to test LA-ICP-MS: La0.83Sr0.17Ga0.83Mg0.17O2.83 (LSGM), one of the most promising electrolytes for IT-SOFCs, and La0.8Sr0.2MnO3 (LSM), a highly representative material of perovskites, which are amply used to design electrode materials. A two-layer system screen-printed onto an LSM pellet (LSM-LSGM-LSM pellet) was successively sintered at a typical processing temperature, i.e. 1300 °C, for a short time (1h). Elemental spatial distribution was determined by line profile analyses carried out on fracture surfaces; for comparison SEM-EDS line profiles were tested on the same surface. LA-ICP-MS line profile analysis evidenced that, notwithstanding the relatively low sintering temperature, and short firing time (1 h per sintering), manganese cation diffusion into LSGM is relatively abundant, in agreement with previous literature reports and present EDS results. While line scan EDX analyses are not conclusive as for Ga and Mg diffusion, LA-ICP-MS shows that both ions diffuse across both interfaces, and Ga diffuses even over very long distances into the LSM pellet; on the contrary, only trace amounts of Mg can be found far from the LSGM/LSM interface

Durability of Solid Oxide Cells

In recent years extended focus has been placed on monitoring and understanding degradation mechanisms in both solid oxide fuel cells and solid oxide electrolysis cells. The time-consuming nature of degradation experiments and the disparate conclusions from experiment reproductions indicates that not all degradation mechanisms are fully understood. Traditionally, cell degradation has been attributed to the materials, processing and cell operating conditions. More recently, focus has been placed on the effect of raw material and gas impurities and their long term effect on cell degradation. Minor impurities have been found to play a significant role in degradation and in some cases can overshadow the cell operation condition related degradation phenomenon. In this review, several degradation diagnostic tools are discussed, a benchmark for a desirable degradation rate is proposed and degradation behaviour and mechanisms are discussed. For ease of navigation, the review is separated into the various cell components - fuel electrode, electrolyte and oxygen electrode. Finally, nanoparticle impregnate stability is discussed