FeTiO3 as anode material for sodium ion batteries: from morphology control to decomposition

Ilmenite, general formula FeTiO3, has been proposed as possible conversion anode material for lithium- and sodium-ion batteries, with theoretical capacity of 530 mAhg−1. Experimentally, the observed specific capacity for pristine ilmenite is far away from the theoretical value; for this reason, the control of morphology via alkaline hydrothermal treatment has been proposed as possible strategy to improve the electrochemical performance. At the same time FeTiO3 is prone to react with sodium and potassium hydroxide, as already demonstrated by studies on the degradation of ilmenite for the extraction of TiO2. In this paper we demonstrate that the alkaline treatment does not induce a morphological modification of the FeTiO3 powders but involved the degradation of the precursor material with the formation of different phases. A complete physicochemical and electrochemical characterization is performed with the aim of correlating structural and functional properties of the obtained products.