Dual Design on Hierarchically Hollow MoTe2/C with Ion/Electron Channel Engineering for High-Performance Sodium Storage.

Transition-metal tellurides have been investigated as novel anode materials for application in sodium-ion batteries (SIBs) due to their rich active sites and unique and controllable layered nanostructures. However, the weak structural strength and inferior intercalation/deintercalation kinetics inhibit the development of transition-metal tellurides. In this work, MoTe2/C composites with two different hollow nanostructures are designed and prepared. By adjustment of the precursor structure, MoTe2/C-2 exhibits superior sodium-storage performance because of its uniquely hollow nanostructure with self-assembled 2D flexible nanosheets grown on the external surface. MoTe2/C-2 delivers a higher specific capacity (276 mAh g-1 at 0.1 A g-1 after 300 cycles), much more than MoTe2/C-1 (201 mAh g-1 at 0.1 A g-1 after 300 cycles), and exhibits a long-time cycling performance (131 mAh g-1 at 1 A g-1 after 2000 cycles). The excellent sodium-storage performance derived from the rational structure design is beneficial for shortening the ion paths, facilitating the sodiation/desodiation process, and reinforcing the intrinsic structural stability, thus boosting the reaction kinetics and prolonging the cycling life. Meanwhile, the assembled full-cell maintains 101 mAh g-1 at 0.1 A g-1 after 50 cycles and lights an electric watch. The findings provide several new views for preparation of more transition-metal tellurides with multi-ion/electron migration channel engineering.

Reshaping carbon-coated Mn2Mo3O8 nanotubes and enhanced sodium storage performance.

Mn2Mo3O8/C nanotubes are successfully reshaped from micron-sized MnMoO4 blocks using a simple microwave-combined calcination method with dopamine as both scissors and carbon source. The synthesized Mn2Mo3O8/C nanotube (MMOC-2) exhibits enhanced sodium storage performance as anodes for half-cell (217 mA h g-1 with ca. 99% coulombic efficiency after 500 cycles) and full-cell (capacity retention of 75% after 100 cycles), which is attributed to the uniquely reshaped nanostructures with abundant active sites, short ion diffusion path and fast charge transfer.