Quantum mechanics

Catalysis

Engineering

Oxide

Electrochemistry

Metallurgy

Materials science

Cathode

Capacity loss

Superlattice

Transition metal

Power (physics)

Biochemistry

Chemical engineering

Superstructure

Physical chemistry

Redox

Thermodynamics

Physics

Nanotechnology

Energy storage

Chemistry

Electrode

Optoelectronics

Advanced Energy Materials

Layered transition metal oxides are appealing cathodes for sodium‐ion batteries due to their overall advantages in energy density and cost. But their stabilities are usually compromised by the complicated phase transition and the oxygen redox, particularly when operating at high voltages, leading to poor structural stability and substantial capacity loss. Here an integrated strategy combing the high‐entropy design with the superlattice‐stabilization to extend the cycle life and enhance the rate capability of layered cathodes is reported. It is shown that the as‐prepared high‐entropy Na 2/3 Li 1/6 Fe 1/6 Co 1/6 Ni 1/6 Mn 1/3 O 2 cathode enables a superlattice structure with Li/transition metal ordering and delivers excellent electrochemical performance that is not affected by the presence of phase transition and oxygen redox. It achieves a high reversible capacity (171.2 mAh g −1 at 0.1 C), a high energy density (531 Wh kg −1 ), extended cycling stability (89.3% capacity retention at 1 C for 90 cycles and 63.7% capacity retention at 5 C after 300 cycles), and excellent fast‐charging capability (78 mAh g −1 at 10 C). This strategy would inspire more rational designs that can be leveraged to improve the reliability of layered cathodes for secondary‐ion batteries.

High‐Entropy and Superstructure‐Stabilized Layered Oxide Cathodes for Sodium‐Ion Batteries