Atomic‐Level Interactions Enable “Near‐Zero Strain” Cathodes for Ultra‐Stable Aqueous Magnesium‐Ion Batteries

ABSTRACT Aqueous magnesium‐ion batteries (AMIBs) are promising next‐generation energy storage devices owing to their high safety, theoretical capacity, and resource abundance. However, the strong electrostatic interactions between Mg‐ions and conventional cathodes usually lead to poor cycling stability and limited rate capability. Herein, we, for the first time, introduced “Near‐Zero Strain” engineering in AMIBs to developed the proof‐of‐the‐concept high entropy Prussian blue analog (HEPBA) cathodes materials with ultra‐stable cycling performance. The atomic‐level interactions and long‐range disordered lattice strain field enable HEPBA to spontaneously respond to ion intercalation‐induced stress with reversible changes in lattice structure, achieving one of the best long‐term stability among AMIBs (above 96.7% capacity retention after 20 000 cycles at a high current density of 5.0 A g − 1 ). Meanwhile, diverse metal atoms with overlapped d ‐band toward optimized HEPBA features efficient charge compensation with drastically enhanced rate capability (over 80.1 mAh g −1 at 5.0 A g − 1 ). Overall, the novel near‐zero strain engineering strategy toward cathode materials in this work revealed the enormous potentiality to improve multivalent‐ion batteries performance.