Ultrafast Sodium Full Batteries Derived from XFe (X = Co, Ni, Mn) Prussian Blue Analogs

Abstract

redox pair of Fe 2+ /Fe 3+ . In order to further improve the electrochemical capability of PB-type cathodes, the evolved manners, containing size-controlled, crystalline increased, and elements substituted, are usually employed. [5] Note that size reduction could broaden the energy distribution of surface and induce more ions adsorbing that brought them more to participate in the redox reaction. [6] As shown by previous reports, [7] high crystallinity always indicated that less coordinated water would occupy the [Fe(CN) 6 ] vacancies, giving rise to the stability of FeCNFe bridge, followed by the considerable capacity at large current density. Importantly, through the replacement of Fe atoms by metal ions (Ni, Co, and Mn), the evolution of physical-chemical features could be effectively tuned, like the morphology, crystalline, and internal pore structure, etc. [5b] For example, the Nidoped PB structure was investigated with the different contents of Ni-doped, and it is obvious that the optimized sample could deliver a capacity of ≈55 mAh g −1 . [5b] It should be noted that the substitutions of heteroatoms (Ni, Co, and Mn substituted Fe ions of PBs) have not been systemically investigated on the effect of the physicalchemical traits in details.Alternatively, restricted by weak Na-storage capacity of traditional anodes, the explorations of new materials with both satisfactory capacity and ultrafast rate ability are urgent. [8] Meanwhile, PBs as a controllable precursor have been utilized to provide great architecture with various element component such as hollow Fe 2 O 3 microboxes and NiS nanoframes, etc. [2b] Notably, compared to metal-oxide/sulfur, metal-selenides show lower energy consumption of conversion reaction, owing to its weak electronegativity (2.5) and high electronic kinetics (1 × 10 −5 S m −1 ). [9] However, their electrochemical properties are still limited by the similar issues of conversion-type materials, containing the volume swelling and the dissolution of polysulfide/polyselenide during cycling. [10] Fortunately, in the process of transformation from cathodes to anodes of PBs, the CN groups would be effectively turned into nitrogen-doped carbon, which boosts the alleviation of volume change and the stabilization of by-products. Moreover, it is found that foreign cations assisted metal-selenide would bring about more active defects and exposed edge sites. [11] Bestowed by the experiences Exploring high-rate electrode materials with excellent kinetic properties is imperative for advanced sodium-storage systems. Herein, novel cubic-like XFe (X = Co, Ni, Mn) Prussian blue analogs (PBAs), as cathodes materials, are obtained through as-tuned ionic bonding, delivering improved crystallinity and homogeneous particles size. As expected, Ni-Fe PBAs show a capacity of 81 mAh g −1 at 1.0 A g −1 , mainly resulting from their physical-chemical stability, fast kinetics, and "zero-strain" insertion characteristics. Considering that the combination of elements incorporated with carbon may increase ...

Interfacial Bonding of Metal‐Sulfides with Double Carbon for Improving Reversibility of Advanced Alkali‐Ion Batteries

“…And, the peak located at about 150 cm −1 is detected, which was indexed to the stretching vibration of SbSb bonds. [ 13e,14 ] Interestingly, with the introduction of carbon, the location of M‐Sb 2 S 3 @DC has a shift toward high wavenumbers than that of M‐Sb 2 S 3 , preliminarily verifying the formation of SbC bonds. That is to say, bonding carbon atoms with Sb could render the enhanced vibration of SbSb bond with blue shift, which would serve as electrons‐diffusion bridge to improve ion‐storage performances.…”

“…[ 3a,4d,12 ] Moreover, it is found that the peak intensity of M‐Sb 2 S 3 is stronger than that of M‐Sb 2 S 3 @DC, perhaps ascribed that introducing carbon could inhibit the exposure of basic material. [ 2f,13 ] But, the peaks of carbon were not observed, mainly derived from the high crystalline of M‐Sb 2 S 3 . Further exploring the crystal structure, Raman spectrum was displayed in Figure 1b,c.…”

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

“…Full cells using PBA cathodes have been investigated and demonstrate their potential as well 137. Dehydrated air‐stable rhombohedral Na 1.92 Fe 2 (CN) 6 with few Fe(CN) 6 vacancies showed an initial discharge capacity of 119.4 mAh g −1 , but the initial Coulombic efficiency was only 78% 131.…”

Nonaqueous Sodium‐Ion Full Cells: Status, Strategies, and Prospects

“…Additionally, a major problem with such materials is the presence of interstitial water, which often results in poor cycle stability. Related studies have found that the removal of interstitial water can increase the average voltage and energy density of the full cell to a certain extent (Figure c,d) …”