A Customized Strategy Realizes Stable Cycle of Large-Capacity and High-Voltage Layered Cathode for Sodium-Ion Batteries.

High-voltage P2-NaNiMnO layered oxide cathode exhibits significant potential for sodium-ion batteries, owing to the elevated operating voltage and theoretical energy density beyond lithium iron phosphate, but the large-volume phase transition is the devil. Currently, this type cathode still suffers from stability-capacity trade-off dilemma. Herein, a concept of customized strategy via multiple rock-forming elements trace doping is presented to address the mentioned issue.

Strong Covalent Metal-Ligand Interaction Enables a Fast Kinetic and Structurally Stable Na-Ion Layered Cathode.

Anionic redox chemistry has attracted increasing attention for the improvement in the reversible capacity and energy density of cathode materials in Li/Na-ion batteries. However, adverse electrochemical behaviors, such as voltage hysteresis and sluggish kinetics resulting from weak metal-ligand interactions, commonly occur with anionic redox reactions. Currently, the mechanistic investigation driving these issues still remains foggy.

High Entropy-Induced Kinetics Improvement and Phase Transition Suppression in K-Ion Battery Layered Cathodes.

Layered oxides are widely accepted to be promising cathode candidate materials for K-ion batteries (KIBs) in terms of their rich raw materials and low price, while their further applications are restricted by sluggish kinetics and poor structural stability. Here, the high-entropy design concept is introduced into layered KIB cathodes to address the above issues, and an example of high-entropy layered KMnNiFeCoTiCuMgO (HE-KMO) is successfully prepared. Benefiting from the high-entropy oxide with multielement doping, the developed HE-KMO exhibits half-metallic oxide features with a narrow bandgap of 0.