Facile synthesis and cycling performance maintenance of iron hexacyanoferrate cathode for sodium-ion battery

Xi, Yuming; Lu, Yangcheng

doi:10.1016/j.jpowsour.2021.230554

Cited by 11 publications

(18 citation statements)

References 24 publications

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“…37,38 As will be discussed in the next section, it is K + intercalation, instead of Na + intercalation, that is responsible for the voltage increase, 18,19,22 even though the amount of Na + in the electrolyte is several fold higher than the amount of K + in KFeRT, and such a difference is caused by the difference anion vacancy contents in the two samples. Interestingly, KFe60 exhibits an extra pair of peaks at 2.73 and 3.02 V. The intercalation voltage (2.73 V) agrees with the voltage at which HS Fe is reduced in NaFeFe-PBA cathodes, 12,22 which suggests that an extra process of Na + intercalation may have occurred.…”

Section: Resultssupporting

confidence: 64%

“…As a result, Na-PBAs have delivered some of the best cathode performance for NIBs so far. [10][11][12][13] Interestingly, bigger K + -filled PBAs (K-PBAs), with a similar formula KxM[Fe(CN)6]1-y•zH2O, was initially studied as cathode materials for K-ion batteries (KIBs), [14][15][16] but have also been demonstrated to be appealing cathode materials for NIBs, [17][18][19][20] delivering a comparable capacity to Na-PBAs.…”

Section: Introductionmentioning

confidence: 99%

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Anion vacancy regulated cation intercalation in potassium Prussian blue analogue cathodes for hybrid sodium ion batteries

Wei

Zhai

Tinker

et al. 2022

Preprint

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Fe-based potassium Prussian blue analogues (K-PBAs) are traditionally used as K-ion battery cathodes. Interestingly, K-PBAs are appealing cathodes for Na-ion batteries (NIBs), due to the increased cation intercalation voltage compared to Na-PBAs. In such a hybrid NIB cell, where Na+ is in the electrolyte and K+ is in the PBA cathode, cation intercalation and electrochemical performance of the cathode can be significantly affected by [Fe(CN)6]4- anion vacancy. This work studies the effect of [Fe(CN)6]4- anion vacancy in K-PBAs on regulating K+/Na+ intercalation mechanism in hybrid NIB cells, by comparing two K-PBA cathodes with different vacancy contents. Experimental and computational results demonstrate that introducing a level of anion vacancy can maximize the number of K+ intercalation sites and enhance K+ diffusion in the PBA framework. This facilitates K+ intercalation and suppresses Na+ intercalation, resulting in a K+-dominated and high-discharge-voltage ion storage process in the hybrid NIB cell. The K-PBA cathode with 25% anion vacancy delivers 127 mAh g-1 at 50 mA g-1 and 63 mAh g-1 at 500 mA g-1, as well as retains 87% and 77% capacity after 100 and 300 cycles, respectively. It completely outperforms the counterpart with 7% anion vacancy, which exhibits increased Na+ intercalation but overall deteriorated ion storage. Our results show the promise of hybrid battery systems and the crucial role of vacancy regulation in designing electrode materials for these systems.

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Section: Resultssupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Anion vacancy regulated cation intercalation in potassium Prussian blue analogue cathodes for hybrid sodium ion batteries

Wei

Zhai

Tinker

et al. 2022

Preprint

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“…Stage I was located between 2 and 3.2 V, corresponding to the redox couple of the high-spin Fe 2+/3+ coordinated with N. Stage II showed a slope charge curve between 3.4 and 3.8 V, which could be inferred as a solid-solution mechanism during the extraction/insertion of Na ion, that is, Fe and Mn shared the same M position where Fe atoms partially replace the nitrogen-coordinated Mn atoms in the framework. 11 , 20 Stage III was at 4.0–4.2 V, assigned to the redox couple of low-spin Fe 2+/3+ coordinated with C. Stages I and III could be both attributed to the formation of FeHCF, 21 which contributed half of the total capacity. Noteworthy, the structure after ion exchange exhibited a high capacity of 150 mAh/g at 1 C, almost the same with the MnHCF.…”

Section: Resultsmentioning

confidence: 99%

How Does Ion Exchange Construct Binary Hexacyanoferrate? A Case Study

2022

ACS Omega

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In this work, using electrochemical active Fe as an ion-exchange element (attack side) and the Na x MnFe(CN) 6 slurry with a high solid content (MnHCF) as a template (defensive side), a series of binary hexacyanoferrates are prepared via a simple Mn/Fe ion-exchange process, in which Na x FeFe(CN) 6 (FeHCF) and solid solution Na x (FeMn)Fe(CN) 6 are concentrated on the shell and the core, respectively. The proportions of the two structures are mainly controlled by the competition between the ion-exchange rate in the bulk material and dissolution-reprecipitation rate. Slowing down the attacking rate, such as the use of a chelating agent complexed with the attacker Fe, is advantageous to form a thermodynamically metastable state with homogeneous distribution of elements since the diffusion of Fe 2+ in the solid MnHCF is relatively fast. The shell FeHCF could be adjusted by the dissolution-reprecipitation rate, which is driven by the solubility difference. Adding the chelating agent in the defensive side will promote the dissolution of MnHCF and reprecipitation of FeHCF on the surface. Meanwhile, with the increase of Fe sources, the thickness of the shell FeHCF increases, and correspondingly the content of solid solution decreased due to FeHCF is more stable than solid solutions in thermodynamics. Finally, such a design principle in this case study could also be generalized to other ion-exchange processes. Considering the difference of two components in solubility, the larger difference can make the core/shell structure more clear due to the enhancement of dissolution–reprecipitation route.

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“…We further tested the electrochemical performance of three samples to recognize the effects of interstitial water. The cycling process followed the optimized procedure as previously reported, 18 that is, activating at 1 C within a voltage window of 2−4.2 V first and then cycling within 2−3.8 V. As for the activation process of three samples, region I (2−3.2 V) and II (3.2−4.0 V) corresponded to the Fe HS 3+ /Fe HS 2+ redox site that was influenced by a small amount of Mn doping, and region III (4.0−4.2 V) corresponded to the Fe LS 3+ /Fe LS 2+ redox site with a highly dynamic characteristic. As the interstitial water was removed, the capacity contribution of regions I and II was evidently activated corresponding to the decrease of capacity in region III (Figure 3a).…”

Section: Effects Of Interstitialmentioning

confidence: 99%

“…15−17 Moreover, such a method suffers from low yields that makes it difficult to realize industrial applications. Recently, our group developed a facile method to prepare sodium-rich iron hexacyanoferrate with excellent rate performance, 18 but we still desired to improve the energy density. R e c e n t l y , C h o u 1 9 r e p o r t e d a c u b i c s t r u c t u r e Na 1.60 Mn 0.833 Fe 0.167 [Fe(CN) 6 ] that helped alleviate stress distortion during cycling compared with MnHCF.…”

Section: Introductionmentioning

confidence: 99%

Electrochemically Active Mn-Doped Iron Hexacyanoferrate as the Cathode Material in Sodium-Ion Batteries

2022

ACS Appl. Mater. Interfaces

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In this work, for the performance enhancement of iron hexacyanoferrate, an electrochemically active Mn-doped iron hexacyanoferrate cathode is fabricated via a bottom-up approach. It is found that the pre-treatment of interstitial water and appropriate Mn doping are two keys to achieving higher capacity and higher stability. The interstitial water has a trade-off effect between the alleviation of volume expansion upon Na+ (de)intercalation and the retardation of Na-ion diffusion. The moisture-tailored iron hexacyanoferrate with appropriate Mn doping exhibits a high initial Coulombic efficiency of 94.8%, enhanced capacity and rate performance, and excellent cycling stability. These results benefit from the fact that the extraction/insertion of Na ions from/into the lattice via a solid-solution mechanism correspond to both the slight volume expansion and fast sodium diffusion rate; otherwise, the removal of interstitial water and a higher Mn content might lead to poor cycling stability due to excessive volume expansion resulting from rhombohedral to cubic phase transformation. Finally, the less demand on the control of air humidity for the fabrication of electrodes and the potential for the full cell coupled with hard carbon are also demonstrated, which shows great potential for practical applications.

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Facile synthesis and cycling performance maintenance of iron hexacyanoferrate cathode for sodium-ion battery

Cited by 11 publications

References 24 publications

Anion vacancy regulated cation intercalation in potassium Prussian blue analogue cathodes for hybrid sodium ion batteries

Anion vacancy regulated cation intercalation in potassium Prussian blue analogue cathodes for hybrid sodium ion batteries

How Does Ion Exchange Construct Binary Hexacyanoferrate? A Case Study

Electrochemically Active Mn-Doped Iron Hexacyanoferrate as the Cathode Material in Sodium-Ion Batteries

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