Structural, electrical and electrochemical properties of Na2NixMn2−xFe(PO4)3as positive electrode material for sodium-ion batteries

The design of synthetic Alluaudite cathode materials has attracted much interest. However, their poor electrochemical activity and the limited kinetics have prevented them from practical applications, both stationary and mobile. Therefore, we provide in this work, a comprehensive study on the effect of combining 3d multivalent elements (Ni2+, Mn2+, Fe2+) and small particle sizes on structural, electrical and electrochemical properties of a series of Na2NixMn2−xFe(PO4)3 Alluaudite phases using a plethora of techniques. We systematically investigated the impact of the crystal structure, morphology and the density of the samples on Na-ion transport and the associated activation energies. Electrochemical performances of the prepared phases were investigated as positive electrode on a Na-ion battery by means of galvanostatic charge/discharge technique. An enhanced electrochemical performance was obtained by improving the composition of the slurry and the optimization of the electrolyte formulation, thus, affecting the electrochemical performances and cycling stability.