Significantly enhanced electrochemical performance of a ZnCo2O4 anode in a carbonate based electrolyte with fluoroethylene carbonate

Abstract

The influence of fluoroethylene carbonate (FEC) as an additive to the conventional electrolyte of ethylene carbonate and dimethyl carbonate with lithium hexafluorophosphate on the electrochemical performance of the Li/ZnCo₂O₄ cell has been investigated. The addition of FEC is found to promote the formation of a more uniform and stable solid electrolyte interphase (SEI) layer with the thinner thickness on the surface of ZnCo₂O₄, which could reduce the charge transfer resistance and SEI resistance, increase the diffusivity of the lithium ions in the ZnCo₂O₄ electrode, and improve the stability of ZnCo₂O₄ during the repeated discharge/charge process. In addition, the formation of less LiF on the ZnCo₂O₄ surface could also be observed when FEC is added to the electrolyte, which decreases the interfacial impedance of the electrode materials. The Li/ZnCo₂O₄ cell in the electrolyte with FEC therefore exhibits substantially improved coulombic efficiency, reversible capacity, and long-term stability. The results make us believe that the addition of FEC could be a promising method to fabricate LIBs with improved performance.