Self-assembled MoTe2 hierarchical nanoflowers with carbon coating as anode material for excellent sodium storage performance

Developing a suitable anode material for rapid sodium ion transfer and storage is a common challenge for application of sodium ion batteries (SIBs). As a typical two-dimensional (2D) layered material, some potential advantages can be discovered from MoTe2 such as unique structural feature, abundant active sites and rapid Na+ intercalation/de-intercalation. However, the stacking of layers, collapse of structure and large volume expansion still affect the Na+ storage performance of MoTe2 anode material. In this work, we report a nanoflower like MoTe2/C as an excellent anode material for SIBs, which is synthesized via a simple method containing chelation, preoxidation and tellurization from Mo-PDA, MoOx/C to MoTe2/C. Through controlling the reasonable tellurization temperatures and suitable mass proportion between Mo raw material and dopamine hydrochloride, the best performance of MoTe2/C-600 can be obtained, which shows a higher initial capacity of 580 mAh/g and 250 mAh/g after 100 cycles at 0.1A/g compared with other tested samples. Besides, MoTe2/C-600 delivers an ultra-long time cycling performance of 3000 cycles and the capacity still retains 190 mAh/g at 1.0 A/g. After assembled with Na3V2(PO4)3 (NVP), a full-cell retains 109 mAh/g after 50 cycles at 0.1A/g. The 3D connected network between petals of flower like MoTe2/C can effectively suppress the volume expansion or pulverization to the boost the Na+ storage performance. This work offers new clues to construct MoTe2-based composites with unique and robust nanostructures for electrochemical energy-storage application.