High-entropy engineering enables O3-type layered oxide with high structural stability and reaction kinetic for sodium storage
Xiong Wang, Qiaoling Kang, Jiaze Sun, Zheng Yang, Zhenchao Bai, Lijing Yan, Xianhe Meng, ChuBin Wan, Tingli Ma
Abstract
O3-type layered oxides are considered promising cathode materials for sodium-ion batteries (SIBs) due to their high theoretical capacity, but they often face issues with structural instability and poor sodium-ion diffusion, leading to rapid capacity fading. In this work, we introduce a high-entropy approach combined with synergistic multi-metal effects to address these limitations by enhancing both the structural stability and reaction kinetics. A novel O3-type layered high-entropy cathode material, Na 0.9 Fe 0.258 Co 0.129 Ni 0.258 Mn 0.258 Ti 0.097 O 2 (TMO5), which was synthesized via a straightforward solid-phase method for easy mass production. Experimental analysis combined with in/ex-situ characterization verifies that high-entropy metal ion mixing contributes to the improved reversibility of the redox reaction and O3-P3-O3 phase transition behaviors, as well as the enhanced Na + diffusivity. Benefit from the advantage of structure and composition, the TMO5 exhibits a higher initial specific capacity of 159.6 mAh g −1 and an impressive capacity retention of 85.6 % after 100 cycles at 2 C with the specific capacity of 110.1 mAh g −1 . This work showcases high-entropy O3-type layered oxides as a promising pathway for achieving robust, high-performance SIB cathodes.