A Superlattice-Stabilized Layered Oxide Cathode for Sodium-Ion Batteries.

Sodium-ion batteries are in high demand for large-scale energy storage applications. Although it is the most prevalent cathode, layered oxide is associated with significant undesirable characteristics, such as multiple plateaus in the charge-discharge profiles, and cation migration during repeated cycling of Na-ions insertion and extraction, which results in sluggish kinetics, capacity loss, and structural deterioration. Here, a new strategy, i.e., the manipulation of transition-metal ordering in layered oxides, is proposed to show a prolonged charge-discharge plateau and cation-migration-free structural evolution. The results demonstrate that the transition-metal ordering with a honeycomb-type superlattice can adjust the crystal lattice and suppress cation migration by modifying the crystal strain to realize a large reversible capacity and excellent cycling performance, which are not characteristics of the widely used common layered oxides. These findings can provide new insight that can be used to improve the design of high-performance electrode materials for secondary-ion batteries.