Spray-drying synthesis of Li4Ti5O12 microspheres in pilot scale using TiO2 nanosheets as starting materials and their application in high-rate lithium ion battery

Abstract

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 Li4Ti5O12 (LTO) has been synthesized by using TiO2 nanosheets as precursor through spray-drying for large-scale production. The TiO2 nanosheets are prepared via a facile and scalable wet grinding method. The high aspect ratio TiO2 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) TiO2 nanosheets as starting materials. As a result, through a pilot-scale spray drying process, the LTO reacted from the TiO2 nanosheets shows a pure spinel structure due to the better morphology of TiO2 nanosheets. In contrast, using the unprocessed TiO2 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.