High Crystalline Prussian White Nanocubes as a Promising Cathode for Sodium‐ion Batteries

Abstract

Prussian blue and its analogues (PBAs) have been recognized as one of the most promising cathode materials for room-temperature sodium-ion batteries (SIBs). Herein, we report high crystalline and Na-rich Prussian white Na CoFe(CN) nanocubes synthesized by an optimized and facile co-precipitation method. The influence of crystallinity and sodium content on the electrochemical properties was systematically investigated. The optimized Na CoFe(CN) nanocubes exhibited an initial capacity of 151 mA h g , which is close to its theoretical capacity (170 mA h g ). Meanwhile, the Na CoFe(CN) cathode demonstrated an outstanding long-term cycle performance, retaining 78 % of its initial capacity after 500 cycles. Furthermore, the Na CoFe(CN) Prussian white nanocubes also achieved a superior rate capability (115 mA h g at 400 mA g , 92 mA h g at 800 mA g ). The enhanced performances could be attributed to the robust crystal structure and rapid transport of Na ions through large channels in the open-framework. Most noteworthy, the as-prepared Na CoFe(CN) nanocubes are not only low-cost in raw materials but also contain a rich sodium content (1.87 Na ions per lattice unit cell), which will be favorable for full cell fabrication and large-scale electric storage applications.

Prussian Blue Analogs as Battery Materials

“…47 More sophisticated methods include the use of a single transition-metal source 23,48 and chelating agents such as citrate. 49,50 Yang and coworkers have used the citrateassisted synthesis to achieve vacancies as low as 1% in a cobalt hexacyanoferrate for sodium ion, with a reversible specific capacity of 150 mA hr g À1 , which is approaching the theoretical maximum. 51 They also reported improved cycle life compared with the high-vacancy material, which they attributed to higher electronic conductivity.…”

Hollow Structures Based on Prussian Blue and Its Analogs for Electrochemical Energy Storage and Conversion

“…[49][50][51][52][53][54][55][56][57] For example, when applied in rechargeable batteries, the available channels and rigid structure of the open framework make PBA materials a kind of excellent cathode materials with fast charge transfer kinetics and long cycle life. [59,60] On the other hand, metal oxides and other inorganic materials derived from PB and PBAs have attracted more and more attention. [36] Specifically, PBA has a capable of storing two sodium ions with a theoretical capacity up to 170 mAh g −1 , which is higher than that of another open framework-based cathode material Na 3 V 2 (PO 4 ) 3 (117 mAh g −1 ).…”

Na 3 V 2 (PO 4 ) 3 @NC composite derived from polyaniline as cathode material for high‐rate and ultralong‐life sodium‐ion batteries

“…Similar to LIBs, the performance of SIBs largely depends on the cathode materials. At present, the study on cathode materials of SIBs is mainly concentrated on transition metal oxides, phosphates, pyrophosphate, and Prussian blues . However, the intrinsic properties of these materials, such as serious capacity decay and voltage platform receding because of structural variations during Na + ‐intercalation/removal process or occurring the side reaction, hinder their application in SIBs.…”

“…and Prussian blues. [24][25][26] However, the intrinsic properties of these materials, such as serious capacity decay and voltage platform receding because of structural variations during Na + -intercalation/removal process or occurring the side reaction, hinder their application in SIBs. Compared with them, Na 3 V 2 (PO 4 ) 3 (NVP) with NASICON structure and higher theoretical specific capacity is considered as an ideal cathode material for SIBs.…”