Kinetic pathways of ionic transport in fast-charging lithium titanate
Fast-charging batteries typically use electrodes capable of accommodating lithium continuously by means of solid-solution transformation because they have few kinetic barriers apart from ionic diffusion. One exception is lithium titanate (Li4Ti5O12), an anode exhibiting extraordinary rate capability apparently inconsistent with its two-phase reaction and slow Li diffusion in both phases. Through real-time tracking of Li+ migration using operando electron energy-loss spectroscopy, we reveal that facile transport in Li4+xTi5O12 is enabled by kinetic pathways comprising distorted Li polyhedra in metastable intermediates along two-phase boundaries. Our work demonstrates that high-rate capability may be enabled by accessing the energy landscape above the ground state, which may have fundamentally different kinetic mechanisms from the ground-state macroscopic phases. This insight should present new opportunities in searching for high-rate electrode materials.
Source: ScienceNOW - Category: Science Authors: Zhang, W., Seo, D.-H., Chen, T., Wu, L., Topsakal, M., Zhu, Y., Lu, D., Ceder, G., Wang, F. Tags: Chemistry, Materials Science reports Source Type: news