A high-performance rechargeable Mg²⁺/Li⁺ hybrid battery using CNT@TiO₂ nanocables as the cathode

Porous CNT@TiO₂ nanocables are prepared via an impregnation method combined with calcination, which not only display the illusive capacity of 233.5 mAh g^-1 but also possess outstanding rate performance (144.9 mAh g^-1 at 500 mA g^-1). Compared with TiO₂ nanoparticles and nanotubes, CNT@TiO₂ exhibits the excellent electrochemical performance on account of the unique coaxial nanocable feature (short ion diffusion path, large contact surface area, supernal conductivity, and favorable structure stability), which simultaneously overcomes the aggregation of TiO₂ particles and the collapse of TiO₂ nanotubes. Importantly, there are no significant changes in the morphology and phase after long cycling, meaning that CNT@TiO₂ has a highly structural stability and reversibility. Therefore, CNT@TiO₂ can be applied as a promising cathode material for Mg²⁺/Li⁺ hybrid batteries.