Effects of post-calcination and mechanical pulverization on the electrochemical properties of nano-sized Li₄Ti₅O₁₂ for hybrid capacitors

Great efforts have been devoted for the synthesis of Li₄Ti₅O₁₂ nanoparticles as anode material, because particle size less than 100 nm is the main factor for achieving a high rate capability. In this study, we fabricated nano-sized Li₄Ti₅O₁₂ by high-energy milling operated at 3500 rpm, that it was treated afterwards by post-calcination to improve its pulverized crystallinity. Post-calcination at moderate temperature is found to be effective for improving the electrochemical properties of Li₄Ti₅O₁₂ prepared by mechanical pulverization. Finally, a 100 nm-sized Li₄Ti₅O₁₂ was successfully obtained by optimizing the high-energy milling passing 10 times in chamber and setting post-calcination to 700 °C. The specific capacity significantly depended on the crystallinity of Li₄Ti₅O₁₂ after treated by the post-calcination. The 100 nm-sized Li₄Ti₅O₁₂ showed high-rate capability and good capacity retention of 99.9% after 1500 cycles. It can be explained by the synergistic effect of reduced particle size and improved crystallinity.