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

Abstract

Coordination compounds such as Prussian blue and its analogues are acknowledged as promising candidates for electrochemical sodium storage owing to their tailorable frameworks. However, a key challenge for these electrode materials is the trade-off between energy and power. Here, we demonstrate that Prussian white (Na 3.1 Fe 4 [Fe(CN) 6 ] 3 ) hierarchical nanotubes with fully open framework configurations render extrinsic Na + intercalation pseudocapacitance. The cathode exhibits a capacity up to 83 mAh g -1 at an ultra-high rate of 50 C and an unprecedented cycle life over 10000 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.

Hexacyanoferrate‐Type Prussian Blue Analogs: Principles and Advances Toward High‐Performance Sodium and Potassium Ion Batteries

“…A novel tubular morphology of NaFeHCF was reported by Mai's group through self‐decomposition of Na 4 Fe(CN) 6 in ethylene glycol/water solution ( Figure 14 a,d). [ 144 ] The as‐derived NaFeHCF shows a quadrilateral hollow‐tube morphology with a dimension of 400 nm in width and several micrometers in length, which are orderly assembled by smaller hollow nanoblocks (30‒50 nm). The use of ethylene glycol with adjusted self‐decomposition parameters is able to modify the surface energy of the nuclei causing Ostwald ripening of the NaFeHCF toward the unique morphology.…”

The Cathode Choice for Commercialization of Sodium‐Ion Batteries: Layered Transition Metal Oxides versus Prussian Blue Analogs

“…NaCrO 2 can deliver a highly reversible capacity of ≈120 mAh g −1 , while LiCrO 2 is electrochemically inactive 11. Different cathode materials, including transition metal (M) oxides (Na x MO 2 , x ≤ 1),12–26 hexacyanoferrates (HCF) or Prussian blue and its analogs (PBAs),27–32 polyanionic compounds,33–47 and organic compounds48–57 have been widely studied for SIBs. The substantial growth of exploration on full cell systems, which serve as a bridge between laboratory studies and practical application, clearly reveals the unprecedented interest in and expectation for the commercialization of SIBs (Figure 1c).…”

Ultrahigh Areal Capacity Hydrogen‐Ion Batteries with MoO3 Loading Over 90 mg cm−2

“…Faradaic electrodes that can simultaneously deliver high energy capacity comparable to batteries and rate capability comparable to supercapacitors, are highly demanded for electrical energy storage, but remain a grand challenge at the moment. [ 1–3 ] The rate capability of Faradaic electrodes is partially determined by the diffusion rate of charge carriers inside electrodes, which in turn depends on the choice of charge carriers. [ 4–6 ] Group IA alkali metal ions in the periodic table have been popularly employed as charge carriers for rechargeable batteries starting from lithium, sodium down to potassium.…”