Engaging tailored capacity of layered WS₂ via sulphur bonding coupled with polyetherimide (WS₂@NC) nanocomposite for high power and improved lithium-ion storage

Layered transition metal sulfides have drawn great research attention due to their excellent properties for energy storage and conversion devices. However, there is a need to innovate effective approaches to enhance the performance of metal sulfides for modern energy storage devices. Herein, a rational surface engineering strategy was adapted to design tungsten disulfide nanosheets coated polyetherimide (WS₂@PEI) nanocomposite by facile sol-gel method combined with a subsequent pyrolysis. The WS₂@NC nanocomposite exhibits excellent lithium-ion storage properties as compared to pristine WS₂ nanosheets. The origin of enhanced performance of WS₂@NC nanocomposite is carbon-sulphur (C–S) bonding with WS₂, offered by thermally stable polyetherimide (N–C). The increased strength of charging is subjected to C–S and N–C bindings, which significantly enhanced the active sites and defects in WS₂@NC nanocomposite framework. The thin porous carbon layer provided elasticity to control the volume expansion during the lithium ions (Li⁺) insertion/deinsertion, while nitrogen and sulphur components offered more active sites and defects in the nanocomposite for reversible adsorption of Li⁺ ions. Thus, the WS₂@NC nanocomposite could deliver high reversible specific capacity of 712 mAh g⁻¹ at 0.1 A g⁻¹ after 100 cycles and 417.6 mAh g⁻¹ even at high current density of 0.8 A g⁻¹ with 99% average coulombic efficiency.