Defect-Induced and Synergistic Na-Ion Storage Capability of TiO₂(B)@MoSe₂/Carbon Trinity for Ultrafast and Ultralong Cycling

Abstract

Currently, there remains a challenge to achieve an anode material with high capacity, ultrafast charge/discharge capability, and ultralong cycling life for sodium-ion batteries (SIBs). This work presents the designed synthesis of TiO 2 (B)@ MoSe 2 /carbon trinity with a defect-rich structure and synergistic Na + storage capability. In the ternary nanocomposites, TiO 2 (B) is doped with nitrogen (N-TiO 2 (B)), carbon is doped with both nitrogen and phosphorus (N,P-C), and few-layer and ultrasmall size MoSe 2 is strongly embedded into N,P-C via the Mo−N and Mo−C chemical bonds. Such a defect-rich structure not only provides abundant active sites for Na + storage but also facilitates the charge-transfer reactions at the interface of the heterogeneous phases. In addition, such a N-TiO 2 (B)@MoSe 2 /N,P-C trinity allows synergistic Na + storage capability, where MoSe 2 provides a high capacity, N,P-C accelerates the charge-transfer reactions and reduces the solid/electrolyte interphase resistance, and N-TiO 2 (B) works as an ultrastable skeleton for solidation/desodiation reactions. The as-prepared nanorod-like product manifests a high specific capacity of 568.5 mAh g −1 at 0.1C, ultrafast charge/ discharge capability, and ultralong cycling life (a capacity retention of 88.9% after 5000 cycles at 20C).