Spray-drying synthesis of Li ₄ Ti ₅ O ₁₂ microspheres in pilot scale using TiO ₂ nanosheets as starting materials and their application in high-rate lithium ion battery

Spray-drying technique has been widely used for synthesis of energy storage materials due to its low cost and easy scale up. However, in mass production, this method usually suffers from the incomplete solid-state reaction owing to the aggregation or poor reactivity of precursors caused by their large particle size and unfavorable morphology. In this study, spinel Li ₄ Ti ₅ O ₁₂ (LTO) has been synthesized by using TiO ₂ nanosheets as precursor through spray-drying for large-scale production. The TiO ₂ nanosheets are prepared via a facile and scalable wet grinding method. The high aspect ratio TiO ₂ nanosheets can efficiently reduce the diffusion length of Li element during the solid-state reaction leading to higher reactivity. It has been found that the temperature required for the formation of LTO phase can be significantly reduced by using the two-dimensional (2D) TiO ₂ nanosheets as starting materials. As a result, through a pilot-scale spray drying process, the LTO reacted from the TiO ₂ nanosheets shows a pure spinel structure due to the better morphology of TiO ₂ nanosheets. In contrast, using the unprocessed TiO ₂ as precursor, the resulting LTO still reveals other impure phases leading to a poor electrochemical performance. The pure LTO shows a higher discharge capacity of ∼160.8 mAh/g at 0.1 C, with an excellent rate performance and superior cycling life in comparison with the LTO containing impurity phases.