An electrochemical study of Fe1.18Sb1.82 as negative electrode for sodium ion batteries

摘要: Abstract The mechanism of the electrochemical reaction between FeSb2 and sodium in half cells has been very recently reported [1,L.Baggetto, H.-Y. Hah, C. E. Johnson, A. Bridges, J. G. M. Veith, Phys.Chem.Chem.Phys. 16 (2014) 9538]. Its activity, initially limited, seems based on an incomplete desodiation Na3Sb formed during first discharge occurrence a “Fe4Sb” alloy inactive cell. However, no more than two charge/discharge cycles were shown. With this work we shed light ion battery electrode properties another solid Fe-Sb system (Fe1.18Sb1.82). Capacity retention different electrolyte configurations containing NaClO4 as salt by setting cycling voltage limits are A discussion about impact additive such fluoroethylene carbonate (FEC) performance is assisted applying impedance spectroscopy electrode/electrolyte interfaces. When not present electrolyte, surface film onto particles due to decomposition noticed at low values (0.3 V vs. Na/Na+). Further leads growth layer conversely decrease charge transfer resistance several well dispersed metallic products discharged electrode. Upon charging, firstly decomposed and/or dissolved increases. Beyond 1.05 V Na/Na+, second film, nature from one appears fresh antimony or FexSby poorly crystallized Na3Sb. FEC added interface influenced each stage charge. suppresses voltages decreases any stage. charging beyond films less resistive absence FEC. Therefore, constructive effect cell capacity upon cycling. Finally lowest limit 0.2 V Na/Na+ does result improvement cycling, but halves compared ones obtained 0 V voltage.