Architectural design and phase engineering of N/B-codoped TiO2(B)/anatase nanotube assemblies for high-rate and long-life lithium storage

Abstract

TiO₂ polymorphs hold great promise as anode candidates in lithium-ion batteries (LIBs) because of their low cost, enhanced safety and high power capability, but they suffer from poor electrical conductivity and low lithium-ion mobility. Herein, an attractive nanoassembly made of ultrathin TiO₂ nanotubes with selected phases and hetero-atom doping was developed through a mild ionothermal reaction. The grain interface of TiO₂(B)/anatase, N/B codoping, and nanoassembly were elaborately engineered. They offer effective nanohighways for fast electronic and Li-ion transport, when applied as an anode in LIBs. The carbon-free, N/B-codoped TiO₂(B)/anatase nanotube nanoassemblies exhibit exceptionally high rate capability and good durability (160 mA h g⁻¹ at 12 A g⁻¹ and retaining 140 mA h g⁻¹ even after 500 cycles). This work demonstrates that the integrated design of surface states and electronic structures plays a crucial role in exploring new capabilities of TiO₂ polymorphs for electrochemical energy storage.