Detailed investigation of a NaTi₂(PO₄)₃ anode prepared by pyro-synthesis for Na-ion batteries

NaTi₂(PO₄)₃ nanoparticles were synthesized by a facile polyol-assisted pyro-synthetic reaction. The nitrogen sorption isotherm of the synthesized material shows a surface area of 110.787 m² g⁻¹, in comparison to 20.984 m² g⁻¹ for pristine material obtained by a solid state method. Moreover, the as-prepared material exhibits much higher capacity, better rate performance and lower electrochemical polarization, of which the excellent electrochemical performance is mainly attributed to uniform particle distribution, good structural stability, high specific surface area, significantly enhanced diffusion coefficient and good conductivity. Through systematic studies using a galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) at different states of charge and discharge, the Na⁺ diffusion coefficient shows a minimum value at the end of the two-phase region.