Highly Rich 1T Metallic Phase of Few-Layered WS2 Nanoflowers for Enhanced Storage of Lithium-Ion Batteries

Transition-metal dichalcogenides (TMDs), a two-dimensional (2D) nanostructured material, has, to a greater extent, technological applications in catalysis, sensors, lithium-ion batteries, and optoelectronic devices due to their unique structure and electrical properties. Recently, the 2D TMD tungsten disulfide (WS2) has been regarded as one of the most promising anode candidates for lithium-ion batteries. However, the exploration of the WS2 sheets with the 1T metallic phase still remains a prodigious challenge to improve its conductivity and cycling stability in the application of lithium-ion batteries. In this work, the highly rich 1T few-layered WS2 nanoflowers (referred to as rich 1T WS2 NFs) were synthesized, exhibiting a rich 1T metallic phase with few-layered structures around the active edge sites of the NFs for achieving a fast electron/ion transfer, thereby delivering the enhanced cycling performance and lithium storage. The rich 1T WS2 NFs exhibits an irreversible capacity (charge capacity) of 810 mA h g(-1) at 0.2 C, and after five cycles the average reversible capacity (discharge capacity) exhibits 609, 577, 554, 542, 530, and 504 mA h g(-1), with the increased c- rates of 0.4, 0.6, 0.8, 1, 1.5, and 2.0 C, respectively. In addition, the rich 1T WS2 NFs anode without additional carbon support exhibits an initial capacity of 890 mA h g(-1) and still remains at a capacity of 390 mA h g(-1) after 500 cycles, being better than the 2H WS2 NFs and the bulk WS2 sheets. This excellent rate of performance is further attributed to the rich 1T metallic nature of the few-layered WS2 NFs that could well-promote the excellent cycling stability and rate capability in contrast to the carbon free (i.e., graphene, CNTs) composites. More importantly, the enlarged interlayer spacing (i.e., 0.67 nm) and its rich 1T metallic nature are beneficial for the high capacity and improved long cycling stability and thus makes a potential candidate for the superior Li-ion storage anodes.