Rapid and Energy‐Efficient Synthesis of Disordered Rocksalt Cathodes

Lithium‐rich transition metal oxides with a cation‐disordered rocksalt structure (disordered rocksalt oxides or DRX) are promising candidates for sustainable, next‐generation Li‐ion cathodes due to their high energy densities and compositional flexibility, enabling Co‐ and Ni‐free battery chemistries. However, current methods to synthesize DRX compounds require either high temperature (≈1000 °C) sintering for several hours, or high energy ball milling for several days in an inert atmosphere. Both methods are time‐ and energy‐intensive, limiting the scale up of DRX production. The present study reports the rapid synthesis of various DRX compositions in ambient air via a microwave‐assisted solid‐state technique resulting in reaction times as short as 5 min, which are more than two orders of magnitude faster than current synthesis methods. The DRX compounds synthesized via microwave are phase‐pure and have a similar short‐ and long‐range structure as compared to DRX materials synthesized via a standard solid‐state route, resulting in nearly identical electrochemical performance. In some cases, microwave heating allows for better particle size and morphology control. Overall, the rapid and energy‐efficient microwave technique provides a more sustainable route to produce DRX materials, further incentivizes the development of next‐generation DRX cathodes, and is key to accelerating their optimization via high‐throughput studies. This study proposes a novel synthesis route based on microwave heating for the rapid (≤5 min) and energy‐efficient preparation of high energy density disordered rocksalt (DRX) oxide and oxyfluoride cathode materials. Further, it is shown that DRX cathodes obtained via conventional solid‐state synthesis and via microwave heating have a similar structure, composition, and electrochemical performance.