Synthesis and characterization of ultrathin ZnS(en)0.5 nanolayers and their application as cathodes in lithium-ion batteries

Abstract

Zinc sulfide (ZnS) materials have been attracting much interest as potential conversion electrode materials for Li-ion batteries due to their high theoretical capacity. To improve the capacity of ZnS electrodes, several attempts involving changes in morphology by incorporating additives during the synthesis process have been addressed. For example, the addition of ethylenediamine (en) has been studied and proven to result in the formation of ZnS(en)_0.5 exfoliated materials, which are promising as electrodes in batteries. Herein, we synthesized ZnS(en)_0.5 complex materials using two Zn salt precursors. X-ray diffraction and FTIR characterization revealed the presence of orthorhombic ZnS(en)_0.5 material independent of the synthesis method. SEM images were obtained to correlate the changes in nanoparticle shape and size according to the synthesis method. Additionally, electrochemical test results revealed that the mechanism involved in the charge/discharge phenomena is influenced by the Li⁺ movement into the electrode, not through the ethylenediamine structural channels, but on the surface of ZnS, allowing the formation of Zn-ethylenediamine-S alloys.