Structure and electrochemistry of NaFePO4 and Na2FePO4F cathode materials prepared via mechanochemical route

Косова, Н. В.; Podugolnikov, Vladislav R.; Devyatkina, E. T.; Slobodyuk, A. B.

doi:10.1016/j.materresbull.2014.09.081

Cited by 69 publications

(35 citation statements)

References 17 publications

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“…In the spectral region of internal modes of the phosphate anion, the symmetric ν 1 and asymmetric ν 3 stretching modes are located in the high‐wavenumber region (900–1100 cm −1 ). They are well separated from the bands resulting from the asymmetric ν 4 and symmetric ν 2 bending vibrations that appear in the low‐wavenumber region (500–650 cm −1 ) . The Raman spectrum (Figure b) shows distinct D (≈1345 cm −1 ) and G (≈1595 cm −1 ) bands for both NaFePO 4 and KFePO 4 proving the formation of the carbon coating on the final products, which is consistent with the TGA and TEM studies.…”

Section: Resultsmentioning

confidence: 99%

Earth‐Abundant Alkali Iron Phosphates (AFePO₄) as Efficient Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Solution

et al. 2018

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Water‐splitting systems are essential for clean energy production. The oxygen reduction reaction (ORR) is a key reaction involved in water splitting, which requires a catalyst. The current work explores the possible application of sodium and potassium iron phosphates (AFePO4, A=Na and K) as electrocatalysts for ORR activity. These earth‐abundant iron phosphates were synthesized by the solution combustion synthesis (SCS) technique by using ascorbic acid both as fuel and reducing agent for Fe. The crystal structure was analyzed by Rietveld refinement. The formation of carbon coating was identified by thermogravimetric analysis and Raman spectroscopy. Electrocatalytic properties of AFePO4 were investigated in alkali electrolytes for the first time by using linear sweep voltammetry with a rotating disk electrode (RDE). The ORR activities of these alkali iron phosphates are comparable to that of the Pt/C system. The Tafel slope and electron transfer number of the alkali iron phosphates were calculated. The ORR activity of NaFePO4 was found to be better than KFePO4 and FePO4. This work demonstrates alkali iron phosphates as alternate cost‐effective, novel electrocatalysts for productive ORR activity in alkaline solution.

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Section: Resultsmentioning

confidence: 99%

Earth‐Abundant Alkali Iron Phosphates (AFePO₄) as Efficient Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Solution

et al. 2018

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“…Several promising sodium based cathode materials such as NaFePO 4 4–6 , Na 2 FePO 4 F 7,8 , Na 3 V 2 (PO 4 ) 3 9,10 and Na x TMO 2 (TM = Ti, V, Cr, Mn, Fe, Co and Ni) 11–13 were reported in the experimental studies. Discovery of novel cathode materials is still active to produce high capacity battery to satisfy the growing demand.…”

Section: Introductionmentioning

confidence: 99%

Defects, Dopants and Sodium Mobility in Na2MnSiO4

Kuganathan

Chroneos

2018

Sci Rep

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Sodium manganese orthosilicate, Na2MnSiO4, is a promising positive electrode material in rechargeable sodium ion batteries. Atomistic scale simulations are used to study the defects, doping behaviour and sodium migration paths in Na2MnSiO4. The most favourable intrinsic defect type is the cation anti-site (0.44 eV/defect), in which, Na and Mn exchange their positions. The second most favourable defect energy process is found to be the Na Frenkel (1.60 eV/defect) indicating that Na diffusion is assisted by the formation of Na vacancies via the vacancy mechanism. Long range sodium paths via vacancy mechanism were constructed and it is confirmed that the lowest activation energy (0.81 eV) migration path is three dimensional with zig-zag pattern. Subvalent doping by Al on the Si site is energetically favourable suggesting that this defect engineering stratergy to increase the Na content in Na2MnSiO4 warrants experimental verification.

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“…This is significantly lower than the~50% exchange observed for other Na-based cathodes, such as Na 2 FePO 4 F [32] and Na 2 FeP 2 O 7 [33] when cycled in hybrid-ion cells, showing that the properties of hybrid-ion batteries can be varied based on the alkali-ion selectivity of electrode materials. To increase the degree of the Na/Li electrochemical exchange in Na 3 V 2 (PO 4 ) 2 F 3 , it first needs to be desodiated in a Na cell, and then cycled in a Li cell with the electrolyte enriched with Li ions.…”

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confidence: 66%

Na1+yVPO4F1+y (0 ≤ y≤ 0.5) as Cathode Materials for Hybrid Na/Li Batteries

Косова

Rezepova

2017

Inorganics

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Using Rietveld-refined X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electrochemical cycling, it was established that among sodium vanadium fluorophosphate compositions Na 1+y VPO 4 F 1+y (0 ≤ y ≤ 0.75), the single-phase material Na 1.5 VPO 4 F 1.5 or Na 3 V 2 (PO 4 ) 2 F 3 with a tetragonal structure (the P4 2 /mnm S.G.) is formed only for y = 0.5. The samples with y < 0.5 and y > 0.5 possessed different impurity phases. Na 3 V 2 (PO 4 ) 2 F 3 could be considered as a multifunctional cathode material for the fabrication of lithium-ion and sodium-ion high-energy batteries. The reversible discharge capacity of 116 mAh·g −1 was achieved upon cycling Na 3 V 2 (PO 4 ) 2 F 3 in a hybrid Na/Li cell. Decrease in discharge capacity for the other samples was in accordance with the amount of the electrochemically active phase Na 3 V 2 (PO 4 ) 2 F 3 . Na 3 V 2 (PO 4 ) 2 F 3 showed good cycleability and a high rate of performance, presumably due to operation in the mixed Na/Li electrolyte. The study of the structure and composition of charged and discharged samples, and the analysis of differential capacity curves showed a negligible Na/Li electrochemical exchange, and a predominant sodium-based cathode reaction. To increase the degree of the Na/Li electrochemical exchange in Na 3 V 2 (PO 4 ) 2 F 3 , it needs to be desodiated first in a Na cell, and then cycled in a lithium cell. In this case, the electrolyte would be enriched with the Li ions.

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Structure and electrochemistry of NaFePO4 and Na2FePO4F cathode materials prepared via mechanochemical route

Cited by 69 publications

References 17 publications

Earth‐Abundant Alkali Iron Phosphates (AFePO₄) as Efficient Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Solution

Earth‐Abundant Alkali Iron Phosphates (AFePO₄) as Efficient Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Solution

Defects, Dopants and Sodium Mobility in Na2MnSiO4

Na1+yVPO4F1+y (0 ≤ y≤ 0.5) as Cathode Materials for Hybrid Na/Li Batteries

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Structure and electrochemistry of NaFePO4 and Na2FePO4F cathode materials prepared via mechanochemical route

Cited by 69 publications

References 17 publications

Earth‐Abundant Alkali Iron Phosphates (AFePO4) as Efficient Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Solution

Earth‐Abundant Alkali Iron Phosphates (AFePO4) as Efficient Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Solution

Defects, Dopants and Sodium Mobility in Na2MnSiO4

Na1+yVPO4F1+y (0 ≤ y≤ 0.5) as Cathode Materials for Hybrid Na/Li Batteries

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Product

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Earth‐Abundant Alkali Iron Phosphates (AFePO₄) as Efficient Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Solution

Earth‐Abundant Alkali Iron Phosphates (AFePO₄) as Efficient Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Solution