Understanding the Role of Short-Range Order in High-Entropy Layered Oxides for Energy Storage.

High-entropy layered oxides (HELOs) hold great promise as battery cathodes, yet a fundamental understanding regarding the relationships among their atomic composition, crystallographic phase, and structural order remains lacking. In particular, the characterization of short-range order (SRO) is technically challenging but essential, as SRO directly impacts cation distributions within the lattice and thereby governs lithium-ion diffusion pathways. Here we extend beyond the predominantly studied cubic systems and identify diffuse scattering signatures of SRO in a high-entropy layered oxide with 3 symmetry. Through investigation of four lithiated Mn, Ni, Fe, Co, and Al HELOs of the same composition prepared under different annealing conditions, we determine the relationship among crystallinity, antisite mixing, and SRO and electrochemically measured lithium diffusion behavior. We reveal that SRO achieved through higher annealing temperatures and shorter durations promotes more facile Li transport.