Preparation of oxygen-deficient WO3-x nanosheets and their characterization as anode materials for high-performance Li-ion batteries

To address the large structural and volume changes of commercial WO 3 during charge/discharge, which make this material unsuitable for use in Li-ion batteries (LIBs), we herein prepared oxygen deficient WO 3- x nanosheets on a large scale by thermal treatment of ammonium paratungstate in a reducing atmosphere followed by sonication and freeze-drying. The above nanosheets were employed as LIB anode materials and exhibited a specific capacity and cycling stability significantly exceeding those of oxygen-deficient WO 3- x nanoparticles and commercial WO 3 . In addition, we investigated the effect of nanosheet loading on electrode performance, demonstrating that the best results (Li storage capacity of ∼628 mAh g −1 after 100 cycles at 100 mA g −1 ) were obtained at a nanosheet content of 20 wt%. This excellent performance was ascribe to the good exposure of defects caused by the comparatively small size of WO 3- x nanosheets , which resulted in an increased number of sites and diffusion paths available for Li-ion storage and transfer. The novel electrode-optimized strategy may be extended to the fabrication of other electrodes that use nanomaterials as active substances due to its superior comprehensive performance and low cost.