Mechanochemical treatment of maricite-type NaFePO₄ for achieving high electrochemical performance

In order to satisfy a growing demand for energy storage devices and to create safer and less expensive batteries with high capacity, materials based on easily accessible and environmentally friendly elements with comparatively low atomic weights, such as sodium and iron, have to be used. A thermodynamically stable maricite-type phase of sodium iron phosphate NaFePO₄ (m-NFP) has been considered electrochemically inactive; however, recent studies have questioned this assertion. In this paper, we propose two facile approaches to a scalable synthesis of nanosized m-NFP and its composites with carbon. Initially low capacity of the nanocomposites (15–27 mA h g⁻¹) increases up to ∼150 mA h g⁻¹ after planetary ball-milling, which leads to the formation of defects and electrochemically active amorphous phases.