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

Currently, there remains a challenge to achieve an anodematerialwith high capacity, ultrafast charge/discharge capability, and ultralongcycling life for sodium-ion batteries (SIBs). This work presents thedesigned synthesis of TiO2(B)@MoSe2/carbon trinitywith a defect-rich structure and synergistic Na+ storagecapability. In the ternary nanocomposites, TiO2(B) is dopedwith nitrogen (N-TiO2(B)), carbon is doped with both nitrogenand phosphorus (N,P-C), and few-layer and ultrasmall size MoSe2 is strongly embedded into N,P-C via the Mo-N and Mo-Cchemical bonds. Such a defect-rich structure not only provides abundantactive sites for Na+ storage but also facilitates the charge-transferreactions at the interface of the heterogeneous phases. In addition,such a N-TiO2(B)@MoSe2/N,P-C trinity allowssynergistic Na+ storage capability, where MoSe2 provides a high capacity, N,P-C accelerates the charge-transferreactions and reduces the solid/electrolyte interphase resistance,and N-TiO2(B) works as an ultrastable skeleton for solidation/desodiationreactions. The as-prepared nanorod-like product manifests a high specificcapacity of 568.5 mAh g(-1) at 0.1C, ultrafast charge/dischargecapability, and ultralong cycling life (a capacity retention of 88.9%after 5000 cycles at 20C).