Effects of post-treatments on the electrochemical properties of solid-state reacted Li₄Ti₅O₁₂—high energy milling and annealing

Abstract

This study is designed and performed to verify whether nano-sized Li₄Ti₅O₁₂ particles can be acquired by simple high energy milling from the economic solid-state reacted coarse powder for high power lithium ion battery applications. For this, Li₄Ti₅O₁₂ is synthesized by heat treatment at 800 and 850°C for 3 h using Li₂CO₃ and TiO₂, followed by high energy milling. Even though a comparable particle size to that of expensive wet chemical methods, or even a smaller particle size of 25 nm, can be acquired by 5 h of milling, the electrochemical properties of the particles are found to be deteriorated due to the decrease in Li₄Ti₅O₁₂ crystallinity associated with the milling. On the other hand, a subsequent annealing at 750°C for the milled powder is shown to recover both the capacity and rate capability of the anode electrode owing to the increased crystallinity, indicating the importance of particle crystallinity besides a fine particle size for the enhanced electrochemical properties for high power applications.