Robust assembly of TiO2 quantum dots onto Ti3C2Tx for excellent lithium storage capability

Abstract

TiO₂ has been widely studied as one of the most promising anode materials for lithium-ion batteries (LIBs) due to good structural stability and small volume changes. However, its applications are still greatly affected by its poor electrical conductivity. In this work, ultrasmall TiO₂ quantum dots (QDs) are firmly grown onto 2D Ti₃C₂T_x nanosheets (A-TiO₂/Ti₃C₂T_x), benefiting from the positive regulation of (3-aminopropyl)triethoxysilane (APTES). Interestingly, SiO₂ nanoparticles produced by the hydrolysis of APTES can strengthen the strong coupling of TiO₂ QDs with Ti₃C₂T_x, thereby enhancing the structural integrity of the composite. As expected, the A-TiO₂/Ti₃C₂T_x composite demonstrates an exceptional lithium storage performance, achieving a high capacity of 425.4 mAh/g for 400 cycles at 0.1 A/g, and an outstanding long-term cycling stability. In-situ electrochemical impedance spectroscopy and theoretical analysis unconver that the superior lithium storage performance is attributed to its unique heterostructure and in-situ N doping derived from APTES, which not only reduces the Li⁺ adsorption energy, but also gives the fast charge transfer dynamics.