Crystalline Sb or Bi in amorphous Ti-based oxides as anode materials for sodium storage

A simple synthesis has been developed for watermelon-like nanocomposites with Ti-based oxides as the matrix. Using the case of Sb nanocrystals in amorphous TiPO x as an example, in-situ/ex-situ techniques, first-principle calculations and control experiments confirm that the formation of Ti-based oxides promotes the reduction of Sb 3+ to Sb by NH 3 at an elevated temperature. A similar synthesis process also succeeds for Sb nanocrystals in amorphous TiO 2 and for Bi nanocrystals in amorphous TiPO x , confirming the promising potential of this synthesis. More importantly, the nanocomposite composed by crystalline Sb in an amorphous TiPO x matrix, as the anode material for sodium storage, concurrently exhibits a long cycle life (~1000 cycles) and a high capacity retention (~82%), suggesting the advantages of watermelon-like structures.