Electronic Structure Characterization of Cross‐Linked Sulfur Polymers

Abstract

Cross-linked polymers of elemental sulfur are of potential interest for electronic applications as they enable facile thin-film processing of an abundant and inexpensive starting material. Here, we characterize the electronic structure of a cross-linked sulfur/diisopropenyl benzene (DIB) polymer by a combination of soft and hard X-ray photoelectron spectroscopy (SOXPES and HAXPES). Two different approaches for enhancing the conductivity of the polymer are compared: the addition of selenium in the polymer synthesis and the addition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) during film preparation. For the former, we observe the incorporation of Se into the polymer structure resulting in a changed valence-band structure. For the latter, a Fermi level shift in agreement with p-type doping of the polymer is observed and also the formation of a surface layer consisting mostly of TFSI anions.

Depth-Dependent Understanding of Cathode Electrolyte Interphase (CEI) on the Layered Li-Ion Cathodes Operated at Extreme High Temperature

“…From Figure S6, the S 1s spectra contain two peaks in all of the cycling conditions, a peak about 2472 eV and another peak around 2478 eV corresponding to anionic sulfide species (S 2− ) and S−O components, respectively. 65,66 The strong signal from S−O around 2478 eV mainly results from the salt anion and additive-derived S− O species in the CEI layer. From the intensity of the S−O peaks, it reveals that the S−O surface layer is from the bulk of the materials rather than surface oxidation-induced S−O species.…”