Manipulating Structural Subtlety for High Ion Mobility in Energy Storage Materials
To realize mass-market electric vehicles with long driving ranges, short recharging time and instant acceleration, electrodes that are capable of storing and releasing large quantities of charge in a short period of time are urgently needed. In addition, the materials used must be inexpensive and from sustainable supply chains. The recently discovered Li-excess cation-disordered rocksalts hold the promise to meet these challenges.These materials show facile Li transport enabled by a percolating network of Li-rich environments. Besides, their ability to function without requiring cation ordering has enabled novel cathodes with remarkable chemical diversity. However, the way Li-ions navigate through the long-range disordered lattice is not fully understood. The original purely statistical model assuming that all the cation species are randomly distributed does not always explain the variations observed in experiments. In this talk, I will show that cation short-range order, which is hidden in diffraction, can fully control the local and macroscopic environments for Li-ion transport, and therefore provides another important handle to tailor the performance of cation-disordered cathodes. The knowledge gained about the relationship between the subtle structural order and Li transport is then utilized to predict and realize new candidates with improved electrochemical performance.
Postdoctoral Associate, University of California, Berkeley
Huiwen Ji obtained her Ph.D. in Chemistry from Princeton University, where her research focused on finding new topological matters in binary and ternary chalcogenides with non-trivial electronic structures. Her Ph.D. advisor was Professor Robert J. Cava. Ji is now a postdoctoral associate at University of California, Berkeley, under the supervision of Professor Gerbrand Ceder. She currently studies cation-disordered oxides and oxyfluorides as a new class of high-capacity lithium-ion cathode materials.