Inhomogeneous Coordination in High‐entropy O3‐type Cathodes Enables Suppressed Slab Gliding and Durable Sodium Storage

O3-type layered oxides are highly promising cathodes for sodium-ion batteries (SIBs), however they undergo complex phase transitions and exhibit high sensibility to air, leading to subpar cycling performance and commercial viability. In this work, we report a layered cathode material (NaNi