Unraveling Propylene Oxide Formation in Alkali Metal Batteries
Journal article, 2024

The increasing need for electrochemical energy storage drives the development of post-lithium battery systems. Among the most promising new battery types are sodium-based battery systems. However, like its lithium predecessor, sodium batteries suffer from various issues like parasitic side reactions, which lead to a loss of active sodium inventory, thus reducing the capacity over time. Some problems in sodium batteries arise from an unstable solid electrolyte interphase (SEI) reducing its protective power e. g., due to increased solubility of SEI components in sodium battery systems. While it is known that the electrolyte affects the SEI structure, the exact formation mechanism of the SEI is not yet fully understood. In this study, we follow the initial SEI formation on a piece of sodium metal submerged in propylene carbonate with and without the electrolyte salt sodium perchlorate. We combine X-ray photoelectron spectroscopy, gas chromatography, and density functional theory to unravel the sudden emergence of propylene oxide after adding sodium perchlorate to the electrolyte solvent. We identify the formation of a sodium chloride layer as a crucial step in forming propylene oxide by enabling precursors formed from propylene carbonate on the sodium metal surface to undergo a ring-closing reaction. Based on our combined theoretical and experimental approach, we identify changes in the electrolyte decomposition process, propose a reaction mechanism to form propylene oxide and discuss alternatives based on known synthesis routes.

X-ray photoelectron spectroscopy and gas chromatography

Na-ion batteries

density functional theory

electrolyte decomposition

solid-electrolyte interphase

Author

Daniel Stottmeister

University of Ulm

Leonie Wildersinn

Karlsruhe Institute of Technology (KIT)

Julia Maibach

Karlsruhe Institute of Technology (KIT)

Chalmers, Physics, Materials Physics

Andreas Hofmann

Karlsruhe Institute of Technology (KIT)

Fabian Jeschull

Karlsruhe Institute of Technology (KIT)

A. Gross

Helmholtz

University of Ulm

ChemSusChem

1864-5631 (ISSN) 1864-564X (eISSN)

Vol. 17 3 e202300995

Subject Categories

Inorganic Chemistry

Materials Chemistry

Condensed Matter Physics

DOI

10.1002/cssc.202300995

PubMed

37820026

More information

Latest update

3/7/2024 9