Electrochemical and interfacial behavior of a FeSi_(2.7) thin film electrode in an ionic liquid electrolyte

摘要

A FeSi_(2.7) thin film is deposited on a copper substrate by RF magnetron sputtering of a Fe-Si alloy target. The electrochemical behavior of the FeSi_(2.7) electrode in ionic liquid electrolyte based on 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide is investigated and compared with that of a FeSi_(2.7) electrode in conventional liquid electrolyte. The FeSi_(2.7) electrode in the ionic liquid electrolyte delivers an initial discharge capacity of 756mAh g~(-1) at room temperature, and its discharge capacity is maintained to be 92% of the initial discharge capacity after the 100th cycle. AC impedance and FTIR analysis reveal that the formation of a stable solid electrolyte interphase (SEI) layer on the FeSi_(2.7) electrode in the ionic liquid electrolyte leads to a good capacity retention. This study demonstrates that the FeSi_(2.7) electrode exhibits stable cycling behavior and good interfacial characteristics in the ionic liquid electrolyte without any solvents and additives.