Probing the Na metal solid electrolyte interphase via cryo-transmission electron microscopy.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34031418.
- Also identified by DOI 10.1038/s41467-021-23368-6 and PMC identifier 8144392.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Cryogenic transmission electron microscopy (cryo-TEM) is a valuable tool recently proposed to investigate battery electrodes. Despite being employed for Li-based battery materials, cryo-TEM measurements for Na-based electrochemical energy storage systems are not commonly reported. In particular, elucidating the chemical and morphological behavior of the Na-metal electrode in contact with a non-aqueous liquid electrolyte solution could provide useful insights that may lead to a better understanding of metal cells during operation. Here, using cryo-TEM, we investigate the effect of fluoroethylene carbonate (FEC) additive on the solid electrolyte interphase (SEI) structure of a Na-metal electrode. Without FEC, the NaPF<sub>6</sub>-containing carbonate-based electrolyte reacts with the metal electrode to produce an unstable SEI, rich in Na<sub>2</sub>CO<sub>3</sub> and Na<sub>3</sub>PO<sub>4</sub>, which constantly consumes the sodium reservoir of the cell during cycling. When FEC is used, the Na-metal electrode forms a multilayer SEI structure comprising an outer NaF-rich amorphous phase and an inner Na<sub>3</sub>PO<sub>4</sub> phase. This layered structure stabilizes the SEI and prevents further reactions between the electrolyte and the Na metal.