High‐Throughput Synthesis of Mn‐Based Disordered Rock‐Salt Li‐Ion Cathodes with Improved Rate Capability via Rapid Joule‐Heating

Abstract Manganese‐based disordered rock‐salt (Mn‐DRX) cathodes provide high energy density and exceptional compositional tunability, which enables the rational design and discovery of advanced DRX chemistries. However, exploration across the vast Mn‐DRX design space remains hindered by the slow and energy‐intensive nature of traditional synthesis methods. Here, the Joule‐heating (JH) method is demonstrated to enable rapid and energy‐efficient synthesis of high‐performance Mn‐DRX cathodes. Through a case study of Li _1.2 Mn _0.4 Ti _0.4 O ₂ (LMTO), we show that optimizing DRX materials under rapid synthesis requires controlling both nanoscale short‐range ordering (SRO) and microscale features such as bulk homogeneity and impurity phases, highlighting that microscale features are as critical as SRO. Based on this understanding, we show that a JH‐synthesized LMTO (annealed at 1050 °C just for 10 min) achieves a near‐phase‐pure DRX structure with uniform elemental distribution and reduced SRO compared to furnace‐synthesized LMTO (annealed at 950 °C for 12 h), leading to improved rate capability (161 vs 137 mAh g ⁻¹ at 1 A/g). Additionally, using the JH system, various DRX compositions are synthesized with electrochemical performance comparable to that of furnace‐synthesized counterparts, demonstrating its versatility. These findings demonstrate that rapid JH synthesis offers a robust approach to producing high‐performance Mn‐DRX cathodes, paving the way for high‐throughput discovery across the vast DRX design space.