Prussian White Hierarchical Nanotubes with Surface-Controlled Charge Storage for Sodium-Ion Batteries

Coordination compounds such as Prussian blue and its analogues are acknowledged as promising candidates for electrochemical sodium storage owing to their tailorable and open frameworks. However, a key challenge for these electrode materials is the trade-off between energy and power. Here, it is demonstrate that Prussian white (Na3.1Fe4[Fe(CN)(6)](3)) hierarchical nanotubes with fully open configurations render extrinsic Na+ intercalation pseudocapacitance. The cathode exhibits a capacity up to 83 mA h g(-1) at an ultrahigh rate of 50 C and an unprecedented cycle life over 10 000 times for sodium storage. In situ Raman spectroscopy together with in situ X-ray diffraction analysis reveal that intercalation pseudocapacitance enables full reaction of N-Fe-III/Fe-II sites in Prussian white with a negligible volume expansion (<2.1%). The discovery of surface-controlled charge storage occurring inside the entire bulk of intercalation cathodes paves a new way for developing high power, high energy, and long life-span sodium-ion batteries.