Electrochemical performance of doped hematite/reduced graphene oxide nanocomposites as anode materials for Na-ion batteries

Although lithium-ion batteries (LIBs) still currently represent the dominant electrochemical energy storage systems, the limited availability and geographically uneven distribution of Lisources in the Planet could raise their price and hinder their large-scale implementation. Sodium has a similar chemistry to lithium. Benefiting from the greater abundance and wide geographical distribution of its sources, sodium-ion batteries (SIBs) are emerging as a more sustainable alternative to LIBs, but the development of the SIB technology needs of highly performing electrode materials. Thanks to its chemical stability, high theoretical specific capacity (1007 mAh/g), easy synthesis and environmental friendliness, hematite -Fe2O3) is gathering attention as SIB anode material. However, it suffers from poor electronic transport properties and large volume change during sodiation/de-sodiation cycles. It has been shown that doping the oxide with aliovalent elements [1] or combining it with a conductive additive (e.g. graphene) [2] are successful strategies to partly overcome these limits. In this work, -Fe2O3 -Fe2O3 nanoparticles anchored on reduced graphene oxide (rGO) are synthesized by one-step solvothermal method. The effect of the nominal rGO content of the nanocomposites (50 or 30 wt%) and of the type of dopant (titanium or manganese) on their physicochemical properties and electrochemical performance as active SIB anode materials is investigated. The results indicate that, for fixed rGO content, Ti-doping improves the rate capability at lower rates, whereas Mn-doping enhances the electrode stability at higher rates. Nanocomposites with higher rGO content exhibit better electrochemical performance.