Li₄Ti₅O₁₂-TiO₂ composite anode for high performance full-cell Li-ion battery and Li-ion capacitor applications

Lithium titanate (Li₄Ti₅O₁₂-LTO) having high chemical stability and zero strain property has attracted significant research interest as negative electrode material for Li-ion storage applications. However, its poor conductivity mainly owing to the presence of vacant Ti-3d states results in poor electrochemical performance especially at high rates. This study investigates the incorporation of titania (TiO₂) with LTO in the form of LTO-TiO₂ composite nanoparticles in order to overcome the limitations of LTO. The nanoparticle composite electrode exhibits 150 mAh/g specific capacity at a specific current of 2000 mA/g with superior cycling stability for 5000 cycles and about 77% capacity retention. This high capacity, ultra-long cyclability features could be attributed to the synergistic combination of LTO and TiO₂ and the percolated conductive pathway that facilitate both electron and lithium transport. Its practical use is further demonstrated by fabricating Li-ion storage devices using LTO-TiO₂ composite as negative electrode against LiMn₂O₄ (for battery) and activated carbon (for capacitor) as positive electrodes. Li-ion battery delivered excellent capacity (126 mAh/g) and cycling stability (1000 cycles) at high specific current of 1770 mA/g while the Li-ion capacitor delivered capacitance over 200 F/g and ultra-long cycling stability for 10,000 cycles at specific current of 10,000 mA/g.