High Performance Full Sodium-Ion Cell Based on a Nanostructured Transition Metal Oxide as Negative Electrode.

A novel design of a sodium-ion cell is proposed based on the use of nanocrystalline thin films composed of transition metal oxides. X-ray diffraction, Raman spectroscopy and electron microscopy were helpful techniques to unveil the microstructural properties of the pristine nanostructured electrodes. Thus, Raman spectroscopy revealed the presence of amorphous NiO, α-Fe2O3 (hematite) and γ-Fe2O3 (maghemite). Also, this technique allowed the calculation of an average particle size of 23.4 Å in the amorphous carbon phase in situ generated on the positive electrode. The full sodium-ion cell performed with a reversible capacity of 100 mA h g−1 at C/2 with an output voltage of about 1.8 V, corresponding to a specific energy density of about 180 W h kg−1. These promising electrochemical performances allow these transition metal thin films obtained by electrochemical deposition to be envisaged as serious competitors for future negative electrodes in sodium-ion batteries. [ABSTRACT FROM AUTHOR]