Interface-engineered Li₄Ti₅O₁₂-TiO₂ dual-phase nanoparticles and CNT additive for supercapacitor-like high-power...

The single-pot synthesis of dual-phase spinel-Li₄Ti₅O₁₂ and anatase-TiO₂ (LTO-TiO₂) nanoparticles over all the phase fractions ranging from pure LTO to pure TiO₂ is conducted. Carrying out the process over the complete range enabled the identification of a unique weight ratio of 85:15 (LTO:TiO₂), providing the best combination of capacity, rate capability and cycling stability. We show that for this composition dual-phase nanoparticles have a predominant interfacial orientation of (111)_LTO∣∣(004)_TiO2 , while it is (111)_LTO∣∣(101)_TiO2 for other compositions. This study therefore shows that the dual-phase interface with these specific orientations gives the best performance. The synergistic combination of dual-phase nanoparticles with multi-wall carbon nanotubes improves the performance further. This results in an electrode with supercapacitor-like rate capability delivering high discharge capacities of 174, 127, 119, 110, 101 and 91 mAh g^-1 at specific currents of 2000, 6000, 12 000, 18 000, 24 000 and 30 000 mA g^-1, respectively. A discharge capacity of 174 mAh g^-1 at a specific current of 2000 mA g^-1 with only 0.005% capacity loss per cycle over 3000 cycles is demonstrated. At current densities of 6000, 12 000 and 24 000 mA g^-1, stable cycling is obtained for 1500 cycles. The present work enables nano-engineered interfaces in LTO-TiO₂ dual-phase nanoparticles with an electrochemical performance that is better than its individual components, opening up the potential for high-power Li-ion battery applications.