Publications by authors named "Sebastian Brox"

2 Publications

  • Page 1 of 1

Impact of Selected LiPF Hydrolysis Products on the High Voltage Stability of Lithium-Ion Battery Cells.

ACS Appl Mater Interfaces 2016 Nov 4;8(45):30871-30878. Epub 2016 Nov 4.

MEET Battery Research Center/Institute of Physical Chemistry, University of Münster , Corrensstrasse 46, 48149 Münster, Germany.

Diverse LiPF hydrolysis products evolve during lithium-ion battery cell operation at elevated operation temperatures and high operation voltages. However, their impact on the formation and stability of the electrode/electrolyte interfaces is not yet investigated and understood. In this work, literature-known hydrolysis products of LiPF dimethyl fluorophosphate (DMFP) and diethyl fluorophosphate (DEFP) were synthesized and characterized. The use of DMFP and DEFP as electrolyte additive in 1 M LiPF in EC:EMC (1:1, by wt) was investigated in LiNiMnCoO/Li half cells. When charged to a cutoff potential of 4.6 V vs Li/Li, the additive containing cells showed improved cycling stability, increased Coulombic efficiencies, and prolonged shelf life. Furthermore, low amounts (1 wt % in this study) of the aforementioned additives did not show any negative effect on the cycling stability of graphite/Li half cells. DMFP and DEFP are susceptible to oxidation and contribute to the formation of an effective cathode/electrolyte interphase as confirmed by means of electrochemical stability window determination, and X-ray photoelectron spectroscopy characterization of pristine and cycled electrodes, and they are supported by computational calculations.
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November 2016

Alternative Single-Solvent Electrolytes Based on Cyanoesters for Safer Lithium-Ion Batteries.

ChemSusChem 2016 07 30;9(13):1704-11. Epub 2016 May 30.

MEET Battery Research Center, University of Münster, Corrensstraße 46, 48149, Münster, Germany.

To identify alternative single-solvent-based electrolytes for application in lithium-ion batteries (LIBs), adequate computational methods were applied to screen specified physicochemical and electrochemical properties of new cyanoester-based compounds. Out of 2747 possible target compounds, two promising candidates and two structurally equivalent components were chosen. A constructive selection process including evaluation of basic physicochemical properties as well assessing the compatibility towards graphitic anodes was initiated to identify the most promising candidates. With addition of a film-forming additive in a low concentration, the most promising candidate showed an adequate long-term cycling stability with LiNi1/3 Mn1/3 Co1/3 O2 [NMC(111)] in a full-cell setup using graphite as anode material. The main advantages of the new electrolyte formulation are related to its good thermal behavior, especially with regard to safety in combination with satisfying electrochemical performance.
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July 2016