LAUSR

High-entropy layered oxide materials containing various metals that exhibit smooth voltage curves and excellent electrochemical performances have attracted attention in the development of positive electrode materials for sodium-ion batteries. However, the smooth voltage curve can be obtained by suppression of the Na+ -vacancy ordering, and therefore, Multi-elementalization of metals in the transition metal slab is not required. Here, the Na+ -vacancy ordering is found to be disturbed by dual substitution of TiIV for MnIV and ZnII for NiII in P2-Na2/3 [Ni1/3 Mn2/3 ]O2 . Dual-substituted Na2/3 [Ni1/4 Mn1/2 Ti1/6 Zn1/12 ]O2 demonstrates almost non-step voltage curves with a reversible capacity of 114 mAh g-1 and less structural changes with maintaining a high crystalline structure during charging and discharging. Synchrotron X-ray, neutron, and electron diffraction measurements reveal that dual-substitution with TiIV and ZnII uniquely promotes in-plane NiII -MnIV ordering, which is quite different from the disordered mixing in conventional multiple metal substitution. This article is protected by copyright. All rights reserved.