Preparation and electrochemical performance of nanowire-shaped Na3Mn2−xFex(P2O7)(PO4) for sodium-ion and lithium-ion batteries

Abstract

A series of Fe-doped Na₃Mn_2−xFe_x(P₂O₇)(PO₄) (x = 0, 0.2, 0.4) (abbreviated as NMFP-0/NMFP-0.2/NMFP-0.4) compounds have been successfully prepared using the sol–gel method. The Rietveld refinement results indicate that single-phase Na₃Mn_2−xFe_x(P₂O₇)(PO₄) with an orthorhombic structure can be obtained. Our results reveal that by controlling the raw materials, the molar ratio of the reactants, the stirring rate of the precursor, the annealing temperature rate, and the reaction time, the proportion of nanowires in the morphology increases as the Fe component rises, and the NMFP-0.4 nanowire-shaped compounds show the best electrochemical activity when used as a cathode material for SIBs. Additionally, its specific capacity is enhanced to ∼126 mA h g⁻¹ in the first cycle when operated at 0.1 C and a working potential window of 1.8–4.3 V (vs. Na/Na⁺). The material can also be applied in lithium-ion batteries as an anode and achieves ∼600 mA h g⁻¹ specific capacity at a current density of 0.1 C (1 C = 1000 mA g⁻¹) in a working potential window of 0.01–3 V (vs. Li/Li⁺).