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.