Rapid and Energy‐Efficient Synthesis of Disordered Rocksalt Cathodes

Abstract

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.

NiCo-MOF Nanospheres Created by the Ultra-Fast Microwave Method for Use in High-Performance Supercapacitors

“…In recent years, more and more professionals in numerous fields have grown intrigued with the microwave approach because of its extremely fast reaction efficiency, low experimental costs, and excellent product performance. It is worth noting that the microwave method is an effective way of synthesizing materials with smaller particle sizes and high purities [ 33 , 34 , 35 , 36 , 37 , 38 ]. Hence, in this work, we successfully prepared NiCo-MOF nanospheres by an ultra-fast microwave method, and further studied the electrochemical performance of different synthesis routes via alteration of the microwave power and microwave reaction time.…”

Understanding the limits to short-range order suppression in many-component disordered rock salt lithium-ion cathode materials

“…Incorporating enough fluorine can therefore create lithium-rich regions with high numbers of 0-TM sites, and good lithium transport. However, high levels of fluorine incorporation requires energy-intensive mechanochemical synthesis 31–33 and can lead to phase separation. 30…”

“…Incorporating enough uorine can therefore create lithium-rich regions with high numbers of 0-TM sites, and good lithium transport. However, high levels of uorine incorporation requires energy-intensive mechanochemical synthesis [31][32][33] and can lead to phase separation. 30 An alternative strategy for suppressing unfavourable shortrange ordering in disordered rock salt cathode materials is to substitute many different species on the cation sublattice, creating a "high-entropy" material.…”

Enhanced Electrochemical Performance of Disordered Rocksalt Cathodes Enabled by a Graphite Conductive Additive

“…Lithium-excess disordered rocksalt (DRX) oxides and oxyfluorides have recently emerged as a promising class of next-generation Li-ion cathodes containing earth-abundant elements including Mn and Ti. − DRX cathodes exhibit high reversible capacities (up to 300 mAh g –1 ) by utilizing a combination of transition-metal and oxygen redox processes. − Recent research on DRX cathodes has focused on understanding the synthesis, structure–property relationships, and redox mechanisms in these materials. − However, DRX cathodes are still in their infancy, and several challenges need to be overcome before they can compete with market-dominant chemistries such as LiCoO 2 (LCO) and LiNi x Mn y Co 1– x – y O 2 (NMC). One such challenge is to reduce the carbon content in composite DRX cathodes without compromising the active material’s reversible capacity or cycling stability.…”