DBD plasma-assisted coating of metal alkoxides on sulfur powder for Li-S batteries

Abstract

Sulfur particles coated by activation of metal alkoxide precursors, aluminum-sulfur (Alu-S) and vanadium-sulfur (Van-S), were produced by dielectric barrier discharge (DBD) plasma technology under low temperature and ambient pressure conditions. We report a safe, solvent-free, low-cost, and low-energy consumption coating process that is compatible for sustainable technology up-scaling. NMR, XPS, SEM, and XRD characterization methods were used to determine the chemical characteristics and the superior behavior of Li-S cells using metal oxide-based coated sulfur materials. The chemical composition of the coatings is a mixture of the different elements present in the metal alkoxide precursor. The presence of alumina Al2O3 within the coating was confirmed. Multi-C rate and long-term galvanostatic cycling at rate C/10 showed that the rate capability losses and capacity fade could be highly mitigated for the Li-S cells containing the coated sulfur materials in comparison to the references uncoated (raw) sulfur. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirm the lower charge-transfer resistance and potential hysteresis in the electrodes containing the coated sulfur particles. Our results show that the electrochemical performance of the Li-S cells based on the different coating materials can be ranked as Alu-S>Van-S>Raw sulfur.