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.