Influence of Additives on the Electrochemical and Interfacial Properties of SiOx-Based Anode Materials for Lithium-Sulfur Batteries

The influence of electrolyte additives on the electrochemical and interfacial properties of SiOx-based anodes for lithium-sulfur batteries (Li-S) was systematically investigated. Four different electrolyte additives, namely, lithium nitrate, vinylene carbonate (VC), vinyl ethylene carbonate, and fluoroethylene carbonate (FEC), were added to the bare electrolyte comprising 1 M LiTFSI in tetraethylene glycol dimethyl ether/1,3 dioxolane in a ratio of 1:1 (v/v). The self-extinguishing time (SET) of the liquid electrolytes was measured. The 2032-type half-cells composed of Li/SiOx/Si/C were assembled, and their charge-discharge studies were analyzed at the 0.1 Crate. Upon cycling, the electrode materials were subjected to surface morphology and differential scanning calorimetry analyses. The interfacial properties of SiOx-based electrodes were investigated by electrochemical impedance spectroscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy studies. Among the electrolytes examined, FEC-added electrolytes offered the lowest SET and interfacial resistance values. The superior charge-discharge properties of FEC-added electrolytes were attributed to the formation of a stable solid electrolyte interface layer on the electrode surface. The surface chemistry studies revealed the formation of Li2CO3 and ROCO2Li peaks on the electrode surface.

Automated summary

This study systematically investigated the influence of four different electrolyte additives on the electrochemical and interfacial properties of SiOx-based anodes in lithium-sulfur batteries. Among the additives, FEC was found to offer the lowest self-extinguishing time and interfacial resistance, leading to superior charge-discharge properties attributed to the formation of a stable solid electrolyte interface layer on the electrode surface.