Energy Level Alignment Enhanced Na Ionic Transport in Nickel-Copper-Iron-Manganese Layered Oxides

O3-type nickel-manganese-based layered oxides are among the most promising materials for sodium-ion battery (SIB) cathodes. However, their structural and capacity decay have limited further application. This study presents an energy alignment strategy to enhance the Na ion transport at the plateau region, as well as the battery cyclability. The transition metal ion orbital is modulated by adjusting the TM-O bond length in [TMO 6 ] octahedrons, through the fine-tuning of the Na content and the crystal layer spacing. This varies the TM ion orbital from 3.0 to 3.3 V vs Na + /Na, enabling the alignment between the initial and reversible deintercalation energy. The energy alignment results in an over 1000 times increase in ion transport. The energy-aligned sample, Na 0.80 Ni 0.23 Cu 0.11 Fe 0.25 Mn 0.41 O 2 , showed capacity retention of 78.46% after 500 cycles. This energy alignment strategy can also extend to other layered oxide materials.