Chemically soft solid electrolyte interphase forming additives for lithium-ion batteries
Journal article, 2018

The solid electrolyte interphase (SEI) layer is a key element of lithium-ion batteries (LIBs) enabling stable operation and significantly affecting the cycling performance including life-length. Here we present the concept of chemically soft SEI-forming additives, created by introducing aromatic ring based derivatives of already well-known SEI-formers to render them chemically soft, resulting in 1,3,2-benzodioxathiole 2,2-dioxide (DTDPh), 3H-1,2-benzoxathiole 2,2-dioxide (PSPh), and 1,4,2-benzodioxathiine 2,2-dioxide (PSOPh). A computational DFT based comparison predicts promise with respect to both early and controlled reduction processes. These predictions are verified by basic electrochemical studies targeting appropriate additive reduction potentials i.e. prior to any electrolyte solvent or salt decomposition. In addition, the decomposition paths of the SEI-formers are projected and the end products compared with spectroscopic data for the SEI-layers formed in LIB cells. The SEI-layers formed finally show very good properties in terms of improved capacity retention, improved coulombic efficiency, and reduced resistance for the graphite/electrolyte/LFP full cells made, especially observed for PSOPh. That is due to the preferred C-O bond breaking mechanism, observed also for DTDPh, and supported by the S-C bond breaking mechanism, together resulting in well conductive and good adhesion properties of the SEI-layers. This is expedited by higher softness, eventuating in a formation process stabilizing some of the radicals and/or lowering the kinetic barriers. These positive effects are confirmed both when applying a commercial style electrolyte and for a new generation electrolyte based on the LiTDI salt, where suppression of the TDI anion reduction is truly crucial.

Author

Piotr Jankowski

Warsaw University of Technology

Centre national de la recherche scientifique (CNRS)

Marcin Poterała

Warsaw University of Technology

Niklas Lindahl

Chalmers, Physics, Condensed Matter Physics

W Wieczorek

Warsaw University of Technology

Centre national de la recherche scientifique (CNRS)

Patrik Johansson

Chalmers, Physics, Condensed Matter Physics

Centre national de la recherche scientifique (CNRS)

Journal of Materials Chemistry A

20507488 (ISSN) 20507496 (eISSN)

Vol. 6 45 22609-22618

Areas of Advance

Energy

Materials Science

Subject Categories

Materials Chemistry

Other Chemical Engineering

Other Chemistry Topics

DOI

10.1039/c8ta07936f

More information

Latest update

12/7/2018