Abstract:

Ternary molten salt based on bis(fluoroalkylsulfonyl)amide anions (LiFSA-KFSA-CsFSA) as a new class of electrolyte was applied in lithium-air batteries. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and combustion experiments were employed to explore the electrochemical and physical properties of this molten salt electrolyte. The electrochemical performance of molten salt-based lithium air battery was analyzed by means of charge-discharge measurement coupled with scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicat that LiFSA-KFSA-CsFSA（LKC）molten salt has much higher ionic conductivity and showed good electrochemical stability. With no carbon component, LKC inorganic molten salt was nonflammable. Furthermore, LKC salt could prevent the formation of insulate and insoluble lithium carbonate originated from electrolyte decomposition during cycling. The lithium-air batteries based on LKC molten salt had an initial discharge capacity of 4 258 mA·h·g1, a charge potential of 3.83 V and the coulombic efficiency was 95% at 50 mA·g1, performing better than the common organic electrolyte-based lithium air battery.

Key words: bis(trifluoromethylsulfonyl)amides, lithium-air battery, molten salt electrolyte, lithium carbonate