| Autor: |
Kosova, Nina V., Podugolnikov, Vladislav R., Bobrikov, Ivan A., Balagurov, Anatoly M. |
| Zdroj: |
ECS Transactions; November 2014, Vol. 62 Issue: 1 |
| Abstrakt: |
A series of the mixed sodium-lithium iron fluorophosphates Na2-xLixFePO4F with 0≤x≤1 has been synthesized by mechanochemically assisted solid-state route. Their crystal and local structure, and electrochemical properties were investigated by X-ray and neutron powder diffraction, 57Fe Mössbauer spectroscopy and electrochemical measurements with GITT. Three single-phase compounds Na2FePO4F, Na1.5Li0.5FePO4F and NaLiFePO4F were obtained. The former crystallize with space group Pbcn, while the latter - with Pnma, differing by Na+/Li+distribution. All as-prepared Na2-xLixFePO4F samples are electrochemically active in Li cell pointing to the occurrence of a gradual Na+/Li+ion exchange. Ex situXRD and EDX study indicates that it results in the formation of lithium rich phases: NaLiFePO4F (S.G. Pbcn) for Na2FePO4F and Na0.3Li1.7FePO4F (S.G. Pnma) for Na1.5Li0.5FePO4F. Charge-discharge curves exhibit sloping profiles with an average potential of 3.3-3.4 V vs.Li/Li+. The average value of DLidetermined by GITT is 10-15and 10-16cm2s-1for NaLiFePO4F and Na0.3Li1.7FePO4F, respectively. |
| Databáze: |
Supplemental Index |
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