Controlling Size, Crystallinity, and Electrochemical Performance of Li₄Ti₅O₁₂ Nanocrystals

Synthesis of nanosized lithium ion battery electrode materials with high purity, controllable crystallinity, and uniform sizes is important for high power applications, but it is challenging using conventional methods. Here, we report on a rapid new synthesis approach, which potentially allows for large scale preparation of nanoparticles (NPs) of the promising zero-expansion anodic material, Li₄Ti₅O₁₂ (LTO). A pulsed flow supercritical reactor is used for one-step synthesis, and by adjusting the synthesis temperature and pulse frequency LTO NPs with tunable crystallite size from ∼2 to ∼20 nm and controllable crystallinity (50–100%) can be synthesized in a matter of minutes. The effect of crystallite size and crystallinity on the electrochemical performance of LTO NPs was investigated in half-cells, and excellent properties are observed even for as-prepared NPs used without post-synthesis treatment. The LTO NPs with small crystallite size and high crystallinity show the best high-rate ability and long-term cyclability probably due to a combination of small charge transfer and Li⁺ diffusion impedance