Temperature-induced structural and chemical changes of ultrathin ethylene carbonate films on Cu(111)

Abstract

The interaction of the Li-ion battery solvent ethylene carbonate (EC) with Cu(111) was investigated by scanning tunnelling microscopy (STM) and variable temperature X-ray photoelectron spectroscopy (XPS) under ultrahigh vacuum (UHV) conditions. Between 80 and 420 K, the decomposition of EC occurs along with distinct structural and chemical changes of the adlayer.

Interaction of Ultrathin Films of Ethylene Carbonate with Oxidized and Reduced Lithium Cobalt Oxide—A Model Study of the Cathode|Electrolyte Interface in Li‐Ion Batteries

“…Similar results were also obtained for LiCoO 2− δ . Finally, identical EC‐related core level peaks have also been reported for EC adsorption on Cu(111) at 80 K …”

“…One possible way to determine the initial stages of the SEI formation at the EEI at the atomic/molecular level involves the use of surface science techniques, studying the interaction of individual components of electrolytes, such as the typical key component EC (or other electrolyte components like ionic liquids), with well‐defined model electrodes under idealized ultrahigh‐vacuum (UHV) conditions, which is focus of the ongoing work in our laboratory. Following a previous study on the interaction of EC with Li‐free and lithiated highly oriented pyrolytic graphite (HOPG) as model for the anode, we here report the results of a similar type of study on the interaction of EC with well‐defined LiCoO 2 electrode surfaces, both fully oxidized LiCoO 2 and partly reduced LiCoO 2− δ surfaces, as models for the cathode.…”

“…This was derived from desorption of fragments like C 2 H 4 , C 2 H 4 O, and CO 2 , upon heating (possible products of the above Li‐containing species). Using scanning tunneling microscopy and X‐ray photoelectron spectroscopy (XPS) in combination with dispersion‐corrected density functional theory calculations to study the interaction of ultrathin EC films with Cu(111), we found that adsorbed EC molecules self‐assemble into a well‐ordered 2D arrangement on Cu(111) at 80 K, and that competing desorption and decomposition set in at ≈170 K . Studies on the interaction of battery‐relevant solvents with LiCoO 2 have been conducted for DEC, water, and dimethyl sulfoxide (DMSO) with the samples cooled to ≈110 K .…”

Structure formation and surface chemistry of ionic liquids on model electrode surfaces—Model studies for the electrode | electrolyte interface in Li-ion batteries

“…We first investigated the interaction of individual components of the electrolytes (solvent, shuttle ion), with structurally and chemically well-defined model electrode surfaces under idealized conditions in an ultrahigh vacuum (UHV) environment, focusing on the structure formation and surface chemistry. [20][21][22][23][24][25][26][27][28][29][30] The measurements were performed in the absence of an applied potential between electrode and electrolyte, which is equivalent to the situation under open circuit conditions, employing methods that are sensitive to the adsorbate structure and to the surface chemistry on planar model surfaces such as high resolution scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The experimental work was complemented by dispersion corrected density functional theory (DFT-D) based calculations.…”

Insights into solid electrolyte interphase formation on alternative anode materials in lithium-ion batteries

“…The peak at 533.8 eV in the O 1s spectrum is mainly present at the surface layer and might be related to oxygen atoms in the C-O-C groups of the organic carbonates (or of decomposition products in which this structure motive is still intact). Buchner et al have shown that the O 1s peak of such a group is located at 534.3 eV after ethylene carbonate adsorption on Cu(111) at 80 K and that it shifts to slightly lower BE after warming to 200 K, which leads to decomposition of the molecule [31]. In the F 1s spectrum finally, two distinct peaks can be identified at 685.6 eV and 687.8 eV.…”