N,N-dimethyl fluorosulfonamide for suppressed aluminum corrosion in lithium bis(trifluoromethanesulfonyl)imide-based electrolytes

Effective passivation of aluminum (Al) current collector at high potentials (> 4.0 V vs. Li/Li+) is of essence for the long-term operation of lithium-based batteries. Unfortunately, the non-aqueous liquid electrolytes comprising lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and organic carbonates are corrosive toward Al current collector at high potentials (> 4.0 V vs. Li/Li+), despite their intriguing features (e.g., good chemical stability and high ionic conductivity). Herein, we propose the utilization of N,N-dimethyl fluorosulfonamide (DMFSA) as electrolyte solvent for suppressing Al corrosion in the LiTFSI-based electrolytes. It has been demonstrated that the electrolyte of 1.0 M LiTFSI-DMFSA shows decent ionic conductivities (1.76 mS·cm−1 at 25 °C) with good fluidities (2.44 cP at 25 °C). In particular, the replacement of organic carbonates (e.g., ethylene carbonate and ethyl methyl carbonate) with DMFSA leads to significant suppressed Al corrosion. Morphological and compositional characterizations utilizing scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) reveal that DMFSA favors the formation of insoluble species (i.e., aluminum fluoride (AlF3)) on the surface of Al electrode, which effectively inhibits continuous exposure of fresh Al surface to electrolyte during cycling. This work provides not only a deeper understanding on the Al corrosion in LiTFSI-based electrolyte but also an elegant path to stabilize the Al current collector at high potentials (> 4.0 V vs. Li/Li+), which may give an impetus into the development of lithium-based batteries.