Sulfone-Based Low Fluorine Electrolytes for High-Voltage Cobalt-Free Cathodes

Titelangaben

Klein, Michel ; König, Tobias ; Pahari, Debanjana ; Bianchini, Matteo ; Balducci, Andrea:
Sulfone-Based Low Fluorine Electrolytes for High-Voltage Cobalt-Free Cathodes.
In: Advanced Energy & Sustainability Research. Bd. 7 (2026) Heft 4 . - e202500494.
ISSN 2699-9412
DOI: https://doi.org/10.1002/aesr.202500494

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Abstract

Replacing commercial cathode active materials with lithium nickel manganese oxide (LNMO, spinel) has the potential to increase the energy density of lithium-ion batteries. However, to successfully utilize this material, an alternative to conventional EC-based electrolytes needs to be found, as this solvent is unstable at potentials above 4.7 V vs. Li+/Li. In this context, a novel electrolyte formulation consisting of lithium difluoro (oxalato) borate (LiDFOB) and ethyl isopropyl sulfone (EiPS) is examined. The LiDFOB salt is investigated at various concentrations and demonstrates a good solubility in the EiPS solvent as well as the ability to passivate the aluminum current collector at high potentials. Additionally, EiPS exhibits a high dielectric constant and outstanding thermal and electrochemical stability. In combination with LNMO electrodes, the 1 M LiDFOB in EiPS electrolyte shows the best performance stability among all tested electrolytes with an average 82 mAh g−1 and a discharge capacity retention of 89%, after 100 cycles at 0.33 C. A subsequent ex situ X-ray photoelectron spectroscopy analysis reveals a thinner cathode-electrolyte interface forming during cycling when using EiPS-based electrolytes compared to a benchmark formulation, as well as a lower LiF content, indicating lower impedance of the CEI.