Structure and Electrochemical Properties of NaCu0.2Fe0.8-XMnxO2 Samples (x= 0.4; 0.5; 0.6; 0.7)

Layered oxides, NaxMO2 (M = transition metal ions), have extensively whetted the interest. They have been used as cathode materials for sodium ion batteries in view of the multiple merits they display. In this context, the NaCu0.2Fe0.8-xMnxO2 (x= 0.4; 0.5; 0.6; 0.7) samples are used to be a candidate as battery electrode for sodium ion batteries. These compounds were synthesized using conventional solid states method. Analyzing the DXR measurement corroborated that they crystallize in hexagonal system in the R-3m space group. The refinement of the crystalline structure revealed the O3 structure type for compounds whose x =0.4 and x=0.5 and the P3 structure type for compounds whose x =0.6 and x=0.7. Furthermore, analysis of the valence state of iron, using Mössbauer spectroscopy, reveals high spin Fe3+ in octahedral ligand fields. They are located at two distinct sites. Furthermore, electrochemical measurements of cathodes NaCu0.2Fe0.8−xMnxO2 were undertaken using coin cell type as well as NaPF6 as sodium salt electrolyte. Rate capability tests were evaluated at C/20, C/10, C/5 and C/2 rates. It was proved that the Mn substitution enhances the specific capacity at slow rates as at fast rates.