title: Impact of Selected LiPF6Hydrolysis Products on the High Voltage Stability of Lithium-Ion Battery Cells.
abstract: Diverse LiPF6hydrolysis 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 LiPF6dimethyl fluorophosphate (DMFP) and diethyl fluorophosphate (DEFP) were synthesized and characterized. The use of DMFP and DEFP as electrolyte additive in 1 M LiPF6in EC:EMC (1:1, by wt) was investigated in LiNi1/3Mn1/3Co1/3O2/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.
authors: MEET Battery Research Center/Institute of Physical Chemistry, University of Münster , Corrensstrasse 46, 48149 Münster, Germany.
authors: Ralf
authors: R
authors: Wagner
authors: Institute for Theoretical Chemistry, Ulm University , Albert-Einstein-Allee 11, 89069 Ulm, Germany.
authors: Martin
authors: M
authors: Korth
authors: MEET Battery Research Center/Institute of Physical Chemistry, University of Münster , Corrensstrasse 46, 48149 Münster, Germany.
authors: Benjamin
authors: B
authors: Streipert
authors: MEET Battery Research Center/Institute of Physical Chemistry, University of Münster , Corrensstrasse 46, 48149 Münster, Germany.
authors: Johannes
authors: J
authors: Kasnatscheew
authors: MEET Battery Research Center/Institute of Physical Chemistry, University of Münster , Corrensstrasse 46, 48149 Münster, Germany.
authors: Dennis R
authors: DR
authors: Gallus
authors: MEET Battery Research Center/Institute of Physical Chemistry, University of Münster , Corrensstrasse 46, 48149 Münster, Germany.
authors: Sebastian
authors: S
authors: Brox
authors: MEET Battery Research Center/Institute of Physical Chemistry, University of Münster , Corrensstrasse 46, 48149 Münster, Germany.
authors: Marius
authors: M
authors: Amereller
authors: MEET Battery Research Center/Institute of Physical Chemistry, University of Münster , Corrensstrasse 46, 48149 Münster, Germany.
authors: Isidora
authors: I
authors: Cekic-Laskovic
authors: MEET Battery Research Center/Institute of Physical Chemistry, University of Münster , Corrensstrasse 46, 48149 Münster, Germany.|Helmholtz-Institute Münster, IEK-12, Forschungszentrum Jülich GmbH , Corrensstrasse 46, 48149 Münster, Germany.
authors: Martin
authors: M
authors: Winter
keywords: LiNi1/3Mn1/3Co1/3O2 (NMC) cathode; electrolyte additives; electrolyte aging; high voltage application; lithium-ion batteries