In situ EIS-TEM characterization of electrospun nanofibers for solid oxide electrolysis cells

Session

Stream 1: EMAG - Energy and Energy Storage Materials

Authors

Waynah Lou Dacayan (1), Christodoulos Chatzichristodoulou (1), Wenjing Zhang (2), Kristian Mølhave (3), Iram Aziz (2), Søren Bredmose Simonsen (1)

Affiliations

1. DTU Energy
2. DTU Environment
3. DTU Nanolab

Keywords

electrochemistry, solid oxide electrolysis cell, electrochemical impedance spectroscopy, electrospun fibers

Abstract text

An in situ method allowing simultaneous structural and electrochemical investigation of solid oxide electrolysis cell (SOEC) nanofiber materials is developed for the latter’s thorough characterization. The method integrates electrochemical measurements, including Electrochemical Impedance Spectroscopy (EIS), to Transmission Electron Microscopy (TEM).

To achieve a stable supply of electricity from renewable sources, i.e. from solar and wind power, it is necessary to be able to store excess electricity for later use^1,2. Through electrolysis, SOEC converts electrical energy to chemical energy that is suitable for storage, with high conversion efficiency. However, normally operated and most efficient at high temperature (800-1000°C)^3-7, SOEC materials are prone to severe degradation which limits its use in the commercial scale. It is therefore important to improve the structural performance of the materials without sacrificing its good electrochemical response. This can only become possible if a full characterization of the materials can be acquired in its active state.

In this study, the SOEC nanofiber materials will be prepared through combining sol-gel synthesis and electrospinning. Based on our previous work and literatures, such ceramic nanofiber structure is capable to provide continuous ion conducting path, facilitate mass transports and enlarge triple phase boundaries (TPBs)^8-10.

Using a MEMS based heating and biasing holder, the electrochemical and structural analysis of the materials will be done simultaneously inside an Environmental TEM. For the electrochemical analysis, I-V curves will be acquired in addition to EIS. During characterization, the materials will be exposed to high temperature, electrical potential, and reactive gases to simulate actual operating conditions.

The study will show the structural changes in the material as a function of temperature and time through TEM images. The associated I-V curves and EIS data will be presented, as well as the corresponding real time changes in conductivity as determined from the latter. These results will be correlated to show a complete picture of the materials’ response in an operating environment. The progress towards these goals will be reported.

References

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