Controlled synthesis of N-doped carbon and TiO2 double-shelled nanospheres with encapsulated multi-layered MoO3 nanosheets as an anode for reversible lithium storage.

Abstract

α-Phase molybdenum trioxide (α-MoO3) is one of the promising anode materials for lithium storage due to its high theoretical capacity and unique intercalation reaction mechanism. Herein, through an efficient step-by-step solvothermal synthesis strategy, multi-layered MoO3 nanosheets are encapsulated by nitrogen-doped carbon (NC) and ultrathin TiO2 double-shells to obtain hierarchical core-shell nanospheres (MoO3@TiO2@NC). The unique nanostructure enables shortening the Li+ diffusion distance, buffer the volume change during the intercalation/deintercalation process, and increase the active sites for the electrochemical reaction. Based on the hierarchical nanostructure and the synergistic effect of each component, the MoO3@TiO2@NC electrode exhibits a high Li+ storage capacity around 979.6 mA h g-1 after 200 cycles at 0.2 A g-1, a stable cycle performance of 800.3 mA h g-1 at 1 A g-1 after 700 cycles and an excellent rate capability of 418.0 mA h g-1 at 5 A g-1. Furthermore, the MoO3@TiO2@NC-based coin-type full cell with a commercial LiNi1/3Mn1/3Co1/3O2 cathode exhibited a good cycling stability at 0.2 A g-1 for 100 cycles (∼190 mA h g-1) and rate capability (134 mA h g-1 at 5 A g-1).