Sodium uptake in cell construction and subsequent in operando electrode behaviour of Prussian blue analogues, Fe[Fe(CN)6]1−x·yH2O and FeCo(CN)6

Pramudita, James C.; Schmid, Siegbert; Godfrey, Thomas; Whittle, Thomas A.; Alam, Moshiul; Hanley, Tracey; Brand, Helen E. A.; Sharma, Neeraj

doi:10.1039/c4cp02676d

Cited by 65 publications

(58 citation statements)

References 43 publications

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“…The fraction of the Li‐poor phase continually decreases upon discharge; however not all of it converts at the end, which prevents the material from achieving full capacity (a 1.8 e − transfer with the insertion of 1.8 Li ions). Similar phase separation has been observed during Na + insertion into Fe[Fe(CN)] 6 ] 1− x · y H 2 O, where part of the material does not uptake Na + at all 47. Interestingly, in 23‐PBA, the majority phase exhibits the major change in lattice parameter; conversely, in the case of the dried sample, the majority phase maintains an almost constant cell parameter.…”

Section: Resultssupporting

confidence: 62%

Prussian Blue MgLi Hybrid Batteries

2016

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The major advantage of Mg batteries relies on their promise of employing an Mg metal negative electrode, which offers much higher energy density compared to graphitic carbon. However, the strong coulombic interaction of Mg2+ ions with anions leads to their sluggish diffusion in the solid state, which along with a high desolvation energy, hinders the development of positive electrode materials. To circumvent this limitation, Mg metal negative electrodes can be used in hybrid systems by coupling an Li+ insertion cathode through a dual salt electrolyte. Two “high voltage” Prussian blue analogues (average 2.3 V vs Mg/Mg2+; 3.0 V vs Li/Li+) are investigated as cathode materials and the influence of structural water is shown. Their electrochemical profiles, presenting two voltage plateaus, are explained based on the two unique Fe bonding environments. Structural water has a beneficial impact on the cell voltage. Capacities of 125 mAh g−1 are obtained at a current density of 10 mA g−1 (≈C/10), while stable performance up to 300 cycles is demonstrated at 200 mA g−1 (≈2C). The hybrid cell design is a step toward building a safe and high density energy storage system.

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Section: Resultssupporting

confidence: 62%

Prussian Blue MgLi Hybrid Batteries

2016

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“…The formation of the OP4-phase is a result of increasing oxide layer repulsion as the sodium content in the interlayer space is reduced. 15,[31][32][33] Herein, we report the current-dependent in situ synchrotron XRD analysis of P2-phase Na 2/3 Fe 2/3 Mn 1/3 O 2 . 13,22 Based on these studies, it is necessary to perform in situ structural characterisation at relatively high cycling rates to gain insight into the dependence of structural evolution at these rates, since structure is directly linked with battery performance.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive picture of the current rate dependence of the structural evolution of P2-Na_2/3Fe_2/3Mn_1/3O₂

Sharma

Han²,

Pramudita

et al. 2015

J. Mater. Chem. A

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Cathodes that feature a layered structure are attractive reversible sodium hosts for ambient temperature sodium-ion batteries which may meet the demands for large-scale energy storage devices. However, crystallographic data on these electrodes are limited to equilibrium or quasi-equilibrium information.Here we report the current-dependent structural evolution of the P2-Na 2/3 Fe 2/3 Mn 1/3 O 2 electrode during charge/discharge at different current rates. The structural evolution is highly dependent on the current rate used, e.g., there is significant disorder in the layered structure near the charged state at slower rates and following the cessation of high-current rate cycling. At moderate and high rates this disordered structure does not appear. In addition, at the slower rates the disordered structure persists during subsequent discharge. In all rates examined, we show the presence of an additional two-phase region that has not been observed before, where both phases maintain P6 3 /mmc symmetry but with varying sodium contents. Notably, most of the charge at each current rate is transferred via P2 (P6 3 / mmc) phases with varying sodium contents. This illustrates that the high-rate performance of these electrodes is in part due to the preservation of the P2 structure and the disordered phases appear predominantly at lower rates. Such current-dependent structural information is critical to understand how electrodes function in batteries which can be used to develop optimised charge/discharge routines and better materials.

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“…To date, some in situ X-ray diffraction studies of materials in Na-ion batteries have been published, both from laboratory [15][16][17] and synchrotron X-ray sources [18][19][20] , but none of these have focused on the degradation mechanisms of the electrode materials by overcharge or midterm cycling, until now. In particular, the mechanisms that appear under cell stress or aging conditions, such as overcharging and mid-term cycling are of practical importance to manufacturers.…”

Section: Introductionmentioning

confidence: 99%

Structural evolution of mixed valent (V³⁺/V⁴⁺) and V⁴⁺ sodium vanadium fluorophosphates as cathodes in sodium-ion batteries: comparisons, overcharging and mid-term cycling

et al. 2015

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Sodium vanadium fluorophosphates belonging to the Na3V2O2x(PO4)2F3-2x family of compounds have recently shown very good electrochemical performance versus Na/Na + providing high working voltages (3.6 and 4.1 V) and good specific capacity values. In this work the electrochemical behaviour and structural evolution of two compositions, Na3V2O1.6(PO4)2F1.4 (V 3.8+ ) and Na3V2O2(PO4)2F (V 4+ ), are detailed using time-resolved in-situ synchrotron X-ray powder diffraction. For the first time in sodium-ion batteries the effects of overcharging and mid-term cycling are analyzed using this technique. Differences in the composition of both materials lead to different combinations of biphasic and singlephase reaction mechanisms while charging up to 4.3 V and overcharging up to 4.8 V. Moreover, the analysis of particle size broadening of both samples reveals the higher stress suffered by the V 4+ compared to the more disordered V 3.8+ sample. The more "flexible" structure of the V 3.8+ sample allows for maximum sodium extraction when overcharging up to 4.8 V while in the case of the V 4+ sample no evidence is shown of more sodium extraction between 4.3 V and 4.8 V. Furthermore, the analysis of both materials after 10 cycles shows the appearence of secondary phases due to the degradation of the material or the battery itself (e.g. electrolyte degradation). This study shows examples of the possible degradation mechanisms (and phases) while overcharging and mid-term cycling which is in turn crucial to making better electrodes, either based on these materials or generally in cathodes for sodium-ion batteries.

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Sodium uptake in cell construction and subsequent in operando electrode behaviour of Prussian blue analogues, Fe[Fe(CN)₆]_1−x·yH₂O and FeCo(CN)₆

Cited by 65 publications

References 43 publications

Prussian Blue MgLi Hybrid Batteries

Prussian Blue MgLi Hybrid Batteries

A comprehensive picture of the current rate dependence of the structural evolution of P2-Na_2/3Fe_2/3Mn_1/3O₂

Structural evolution of mixed valent (V³⁺/V⁴⁺) and V⁴⁺ sodium vanadium fluorophosphates as cathodes in sodium-ion batteries: comparisons, overcharging and mid-term cycling

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Sodium uptake in cell construction and subsequent in operando electrode behaviour of Prussian blue analogues, Fe[Fe(CN)6]1−x·yH2O and FeCo(CN)6

Cited by 65 publications

References 43 publications

Prussian Blue MgLi Hybrid Batteries

Prussian Blue MgLi Hybrid Batteries

A comprehensive picture of the current rate dependence of the structural evolution of P2-Na2/3Fe2/3Mn1/3O2

Structural evolution of mixed valent (V3+/V4+) and V4+ sodium vanadium fluorophosphates as cathodes in sodium-ion batteries: comparisons, overcharging and mid-term cycling

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Sodium uptake in cell construction and subsequent in operando electrode behaviour of Prussian blue analogues, Fe[Fe(CN)₆]_1−x·yH₂O and FeCo(CN)₆

A comprehensive picture of the current rate dependence of the structural evolution of P2-Na_2/3Fe_2/3Mn_1/3O₂

Structural evolution of mixed valent (V³⁺/V⁴⁺) and V⁴⁺ sodium vanadium fluorophosphates as cathodes in sodium-ion batteries: comparisons, overcharging and mid-term cycling