In‐situ self‐assembly of core‐shell multi‐metals Prussian blue analogues for high‐performance sodium‐ion batteries

: Metal-organic frameworks (MOFs), such as Prussian blue and its analogues (PB and PBAs) with open frameworks have attracted tremendous attentions as cathode materials for sodium-ion batteries, owing to their simple method of synthesis and high theoretical specific capacity. In this study, core-shell-structured PBAs are prepared by an in situ self-assembly method. Owing to the advantages of both constituents, the as-prepared core-shell PBAs show excellent rate and cycling electrochemical properties through a dual-level-controlled charge-discharge depth mechanism. It delivers a specific capacity of 104.3 mAh g-1 at 0.1 C, as well as a remarkably enhanced cycle performance, giving 88.3 % of its initial capacity over 1000 cycles at 300 mA g-1 . In particular, the coating strategy described herein could be extended to other MOF materials, leading to wider application in energy storage.