Solid-state synthesis of Li4Ti5O12 for high power lithium ion battery applications

• High energy milling using 0.30 and 0.45 mm beads for Li4Ti5O12 synthesis.
• Synthesis of 162 nm-sized pure Li4Ti5O12 by solid-state reaction.
• Spray drying using fine starting materials to confer paste tackiness.
• High capacity of 174 mAh/g and adequate rate properties for high power LIBs applications.

Li4Ti5O12 was synthesized by a solid-state reaction between Li2CO3 and anatase TiO2 for applications to high power lithium ion batteries. The starting materials underwent 6 h of high energy milling using ZrO2 beads with two different sizes, 0.30 and 0.45 mm. The smaller ZrO2 beads resulted in finer starting materials. Spray drying was also performed on the 0.30 mm beads-treated particles to enhance the screen printability of a paste containing this powder. The finer starting materials showed a pure 162 nm-sized Li4Ti5O12 due to the decreased diffusion length for a solid-state reaction, whereas the 0.45 mm beads-treated starting materials resulted in a 242 nm-sized Li4Ti5O12 phase containing 2 wt.% of rutile TiO2 that had transformed from the anatase phase during heat treatment at 800 °C for 3 h. The finer Li4Ti5O12 showed higher charge capacity and better charge/discharge rates than the coarser particles, which highlights the importance of the primary particle size on the electrochemical properties of Li4Ti5O12 for high power applications. The fine Li4Ti5O12 particles had a discharge capacity of 174 mAh/g at 0.1 C and capacity retention of 80% at 10.0 C.