Hierarchical hybrid nanostructure of 1T-tungsten disulfide quantum dots/multihollow capillary bundle-type mesoporous carbon for ultrafast and ultrastable lithium storage

Abstract

Transition metal dichalcogenides such as tungsten disulfide (WS2), a typical 2D layered structure, have attracted increasing attention as promissing anode materials for ultrafast Li-ion batteries (LIBs), because of their high theoretical specific capacity and excellent Li-ion diffusion kinetics. Furthermore, the ionic/electrical properties of WS2, which can improve ultrafast cycling performance, can be effectively enhanced by its unique metallic phase (1T-WS2). Despite these significant advantages, the application of WS2 anodes is limited by critical issues such as large volume expansion and poor ultrafast cycling performance, because the control and synthesis of nano-sized 1T-WS2 crystals is difficult.Therefore, to improve the ultrafast and ultrastable Li storage of LIBs, herein, a novel architecture comprising 1T-WS2 quantum dots (QDs) embedded in mesoporous carbon nanofibers (PCNFs) with multihollow capillary bundle-type mesopores is proposed. This novel hierarchical hybrid nanostructure exhibits a high specific capacity (716.5 mAh g−1 after 100 cycles at 100 mA g−1) and an outstanding rate capability, because of increased Li-ion storage sites and fast Li-ion diffusion and significant ultrafast cycling capacity (528.1 mAh g−1) and long-term cycling stability (87.8% after 1000 cycles) under ultrafast cycling conditions (2000 mA g−1). The increase in the Li storage sites is attributed to the high specific capacity due to the well-dispersed 1T-WS2 QDs in the PCNFs; the increased Li-ion transfer rate is attributed to the high rate capability due to the multihollow capillary bundle-type mesopores; the long-term cycling stability is attributed to the WS2 QDs embedded within the PCNFs, which effectively prevent volume expansion.