Exploration of Na7Fe4.5(P2O7)4 as a cathode material for sodium-ion batteries

Abstract

A novel Na₇Fe_4.5(P₂O₇)₄ compound was fabricated as a cathode for sodium-ion batteries by a mechanical milling assisted solid state method for the first time. The as-prepared material exhibits superior electrochemical performance based on half-cell testing. After uniform carbon coating, it exhibits lower electrochemical polarization, better conductivity and faster sodium ion diffusion kinetics. Benefiting from these advantages, the Na₇Fe_4.5(P₂O₇)₄ was endowed with higher charge–discharge capacity, better cycle life and outstanding rate performance. The high rate capability and good cyclability of this material in non-aqueous electrolytes are advantageous for low-cost and safe battery systems.