Source: https://www.nature.com/articles/nmat4165?error=cookies_not_supported&code=148f41e5-0d77-490a-804e-4da472e5cc31
Timestamp: 2019-04-21 18:35:47+00:00

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One promising energy storage technology is the solid oxide electrochemical cell (SOC), which can both store electricity as chemical fuels (electrolysis mode) and convert fuels to electricity (fuel-cell mode). The widespread use of SOCs has been hindered by insufficient long-term stability, in particular at high current densities. Here we demonstrate that severe electrolysis-induced degradation, which was previously believed to be irreversible, can be completely eliminated by reversibly cycling between electrolysis and fuel-cell modes, similar to a rechargeable battery. Performing steam electrolysis continuously at high current density (1 A cm−2), initially at 1.33 V (97% energy efficiency), led to severe microstructure deterioration near the oxygen-electrode/electrolyte interface and a corresponding large increase in ohmic resistance. After 4,000 h of reversible cycling, however, no microstructural damage was observed and the ohmic resistance even slightly improved. The results demonstrate the viability of applying SOCs for renewable electricity storage at previously unattainable reaction rates, and have implications for our fundamental understanding of degradation mechanisms that are usually assumed to be irreversible.
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This work was supported by the Program Commission on Sustainable Energy and Environment, The Danish Council for Strategic Research, through the SERC project (http://www.serc.dk), contract no. 2104-06-0011, and the Nordic Energy Research Council (NER) project no. 40000. We thank A. Hauch, M. Davodi and H. Henriksen for help and assistance with the experimental work, and other colleagues at DTU Energy Conversion for support and valuable discussions.
C.G. conceived the project and executed the electrochemical experiments and scanning electron microscopy analysis. C.G., M.B.M., S.D.E. and S.H.J. designed the electrochemical experiments. S.D.E. improved/developed the experimental set-up. S.B.S. executed the transmission electron microscopy analysis. C.G. wrote the paper with contributions from S.D.E., S.B.S., S.H.J. and M.B.M.

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