Effect of Long-Range and Local Order of Exfoliated and Proton-Beam-irradiated WSe₂ Nanosheets for Sodium Ion Battery Application

WSe₂ nanosheets were synthesized by mechanical exfoliation via sonication of bulk WSe₂ in organic solvent. The exfoliated WSe₂ nanosheets were separated into two different particle size ranges, and were then irradiated by a proton beam for modification of their local structure, along with the original bulk sample. According to X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) analyses of the samples, the mechanical exfoliation reaction mainly affected the long-range order of the WSe₂ samples, whereas proton beam irradiation influenced the local structure of the two-dimensional WSe₂. To examine the structural dependence of exfoliated and proton-beam irradiated WSe₂ in sodium ion battery (NIB) applications, charge/discharge experiments were carried out, which showed that proton beam irradiation could effectively enhance both the discharge capacity and cycling performance of the WSe₂ samples. This synthetic procedure via proton beam irradiation is expected to be used for the development of new anode materials with increased energy density in NIBs.