Effects of electrolytes additive on the electrochemical performance of Si/disordered carbon composite anode for lithium-ion batteries

摘要

The effect of vinylene carbonate (VC) as electrolyte additive on the electrochemical performances of the Si/disordered carbon (Si/DC) composite electrode / liquid electrolyte interface was studied in this paper. The electrochemical performances of Si/disordered carbon (Si/DC) composite electrode were systematically investigated by constant current charge-discharge. Field scanning electron microscopy (FSEM) was used to observe the change of electrodes in morphology after given cycle numbers. Cyclic voltammetry and electrochemical impedance spectra (EIS) techniques were employed to understand the influences of different electrolytes on the formation of Solid electrolyte interface(SEI) layers. The electrochemical performances were drastically improved by the introduction of a few percent of VC additive. It was found that the SEI layer formed in VC-containing electrolyte has a better resists to the stress caused by large volume variations associated with lithiation and delithiation reactions. This study highlights the importance of the SEI which governs the electrochemical performances of Si/disordered carbon (Si/DC) composite electrode.