Waxberry-like TiO2 with Synergistic Surface Modification of Pyrolytic Carbon Coating and Carbon Nanotubes as an Anode for Li-Ion Battery

Abstract

Titanium dioxide (TiO₂) as an anode material for lithium-ion batteries (LIBs) has the advantages of tiny volume expansion, high operating voltage, and outstanding safety performance. However, due to the low conductivity of TiO₂ and the slow diffusion rate of lithium ions (Li⁺), it is limited in the application of LIBs. Therefore, waxberry-like TiO₂ comodified by pyrolytic carbon coating and carbon nanotubes was prepared in this work. The waxberry-like TiO₂ with nanorods on its surface shortens the diffusion distance of Li⁺. Carbon nanotubes and waxberry-like TiO₂ are tightly combined through electrostatic assembly and form a cross-linked conductive network to provide more electron transmission paths. A thin layer of pyrolytic carbon wraps carbon nanotubes and waxberry-like TiO₂, which enhance the conductivity of the composites and ensure the structural integrity of the materials throughout the cycling process. The experimental data revealed that the discharge-specific capacity of TiO₂@CNT@C is 170.5 mAh g^–1 after 3000 cycles at a large current density of 5 A g^–1, and the discharge-specific capacity is still 143 mAh g^–1 at the superhigh rate of 10 A g^–1, which provides excellent rate performance and cyclic stability. The efficient dual-carbon modification strategy could potentially be extended to other materials.