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 LiNi_1/3Mn_1/3Co_1/3O₂ 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).