Structure and electrochemical properties of the cathode materials Na3Fe2(PO4)3 and Na3Fe2(PO4)3/C

Abstract

This article presents a comparative assessment of the structures and electrochemical properties of Na₃Fe₂(PO₄)₃ and Na₃Fe₂(PO₄)₃/C_x polycrystals obtained by a solid-phase synthesis method.  It has been established that, as a result of carbon doping, the structures of α- Na₃Fe₂(PO₄)₃/C_x polycrystals exhibit changes in symmetry and unit cell parameters compared with those of Na₃Fe₂(PO₄)₃. It has been shown that the use of Na₃Fe₂(PO₄)₃/C_x polycrystals as cathode materials in lithium-ion batteries is more effective than that of Na₃Fe₂(PO₄)₃. Moreover, as the concentration of carbon atoms in the Na₃Fe₂(PO₄)₃/C_x cathode materials increases, the specific capacity of the SIB increases, although this is accompanied by a decrease in structural stability during cycling. The use of Na₃Fe₂(PO₄)₃/C_x compositions (0 < x < 0.5) is advisable as cathode materials in SIB, as this improves the battery’s specific capacity whilst ensuring that the structural stability of the cathodes remains at an acceptable level.