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Activation of Sodium Storage Sites in Prussian Blue Analogues via Surface Etching.

ABSTRACT

Sodium-ion battery (SIB) technologies are known to suffer from kinetic problems associated with the solid-state diffusion of Na(+) in intercalation electrodes, which results in suppressed specific capacity and degraded rate performance. Here, a controllable selective etching approach is developed for the synthesis of Prussian blue analogue (PBA) with enhanced sodium storage activity. Based on time-dependent experiments, a defect-induced morphological evolution mechanism from nanocube to nanoflower structure is proposed. Through in situ XRD measurement and computational analysis, this unique structure is revealed to provide higher Na(+) diffusion dynamics and negligible volume change during the sodiation/desodiation processes. As a SIB cathode, the PBA exhibits a discharge capacity of 90 mAh g(-1), which is in good agreement with the complete low spin Fe(LS)(C) redox reaction. It also demonstrates an outstanding rate capability of 71.0 mAh g(-1) at 44.4 C, as well as unprecedented cycling reversibility over 5000 times.