An Overview of Cation-Disordered Lithium-Excess Rocksalt Cathodes

In the past several years, cation-disordered Li-excess rocksalts (DRXs) have quickly emerged as a new class of promising high-energy Li-ion battery (LIB) cathode materials. These oxides and oxyfluorides often consist of Earth-abundant elements, along with Co-free chemistry, a wide compositional space, and large charge storage capacities. In this Review, we provide an overview on the recent advances in DRX cathodes, with an emphasis on compositions and synthesis, charge storage mechanisms, performances in battery cells, key factors influencing electrochemical performance, and materials degradation mechanisms. As DRX cathode materials are fairly new and they have not yet gone through the extensive optimization process needed for commercialization, we provide perspectives on future directions in developing DRXs that are better alternatives to today's LIB cathodes.