Electrochemical reactivity of Co–Li 2S nanocomposite for lithium-ion batteries

Abstract

The fabrication of Co–Li 2S nanocomposite thin film is reported by pulsed laser deposition (PLD) for the first time. Li 2S–Co nanocomposite thin film is used as storing Li electrodes that have led to promising electrochemical activity and good electrochemical performance. The releasing Li process from the as-deposited Li 2S–Co nanocomposite thin films is confirmed by the ex situ high resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) measurements and may come from the decomposition of Li 2S with and without the interaction of metal Co into CoS 2 and S. The electrochemical reaction mechanism of Co–Li 2S nanocomposite film electrode involving both the formation and decomposition of Li 2S and the lithium extraction/insertion of CoS 2 after the initial charging process is proposed. Our results demonstrate the advantages of using Co–Li 2S nanocomposite in storage lithium materials.