Scalable Synthesis Route for Mn-Rich Disordered Rocksalt (DRX) Cathodes

Li-ion batteries containing conventional cathodes are unlikely to satisfy energy demands in the coming decades due to overreliance on critical resources—namely Co and Ni. Disordered rocksalt (DRX) materials represent a promising class of next-generation cathodes due to their high specific energy (>700 Wh/kg) and compatibility with earth-abundant transition metals (e.g., Mn and Ti). Despite these promising attributes, a major limitation of DRX cathodes is the lack of robust synthesis platforms which enable fine tuning of the material’s structure and performance.

To address this issue, our team recently developed a scalable synthesis route for DRX oxyfluorides involving: (i) a solution-based combustion reaction to prepare a transition metal oxide precursor, followed by (ii) a high temperature reaction with lithiation/fluorination agents. Overall, the approach yields high purity DRX powders which can be prepared at lower temperatures and over shorter timeframes (e.g., 800 °C and 1 h) compared to conventional solid-state processes. Interestingly, these findings demonstrate that adding LiF to the oxide precursor is critical to facilitate DRX phase formation during the second heating step. These Mn-based DRX cathodes exhibit stable cycling performance with reversible capacities up to ~240 mAh/g in Li metal half cells.

This presentation will discuss recent findings for DRX cathodes produced through this two-step reaction route. More specifically, effects of precursor design and annealing profile on the reaction pathway and electrochemical performance will be highlighted. Overall, these results illustrate the merits and opportunities for scalable combustion reactions to produce Co/Ni-free DRX cathodes.

Acknowledgements
This research was conducted at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE). This work is sponsored by the U.S. Department of Energy in the Office of Energy Efficiency and Renewable Energy (EERE) in the Vehicle Technologies Office (VTO) through the Advanced Battery Materials Research (BMR) Program.