Solvent exfoliation stabilizes TiS2 nanosheets against oxidation, facilitating lithium storage applications

Abstract

Titanium disulfide is a promising material for a range of applications, including lithium-ion battery (LIB) anodes. However, its application potential has been severely hindered by the tendency of exfoliated TiS₂ to rapidly oxidize under ambient conditions. Herein, we confirm that, although layered TiS₂ powder can be exfoliated by sonication in aqueous surfactant solutions, the resultant nanosheets oxidise almost completely within hours. However, we find that upon performing the exfoliation in the solvent cyclohexyl-pyrrolidone (CHP), the oxidation is almost completely suppressed. TiS₂ nanosheets dispersed in CHP and stored at 4 °C in an open atmosphere for 90 days remained up to 95% intact. In addition, CHP-exfoliated nanosheets did not show any evidence of oxidation for at least 30 days after being transformed into dry films even when stored under ambient conditions. This stability, probably a result of a residual CHP coating, allows TiS₂ nanosheets to be deployed in applications. To demonstrate this, we prepared lithium ion battery anodes from nano : nano composites of TiS₂ nanosheets mixed with carbon nanotubes. These anodes displayed reversible capacities (920 mA h g⁻¹) close to the theoretical value and showed good rate performance and cycling capability.