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

Abstract

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.