Synthesis, characterization and application of rGO-SnO2-Fe2O3-TiO2 AND rGO-Fe2O3-SnO2-TiO2 ternary nano-composite as electrodes in sodium-ion batteries

Abstract: Rechargeable batteries are an integral part of modern life and technology development as energy sources and energy storage systems. Currently, lithium batteries’ (both rechargeable and non-rechargeable) features and consequently its performance surpasses those of its counterparts by far. For that reason, lithium batteries are leading the battery market. However, their rapid growth and demand is projected to exceed the limited recoverable resources of lithium. Therefore, sourcing equivalent battery types and/or technologies is crucial. Sodium-ion rechargeable batteries are the most credible alternative mainly due to the abundance, even distribution and feasible recovery of this resource. In addition, sodium and lithium have similar physical and chemical properties and thus similar energy storing / supplying mechanisms. However, the larger and heavier sodium-ion has inherently slower diffusion rates and thus experiences a few challenges with the lithium cell configuration such as compatible active electrode material. Therefore, the development of sodium-ion electrode material is the key to the success and commercialization of sodium-ion batteries. The SnO2 and Fe2O3 metal oxides have been reported to exhibit high capacities when used as anode material in sodium-ion batteries although at short life cycles due to the extreme volume expansion they experience during cycling. On the other hand, graphene oxide and TiO2 have been reported to exhibit moderate reversible capacity but for long life cycles due to their insignificant volume change during cycling. Hybrids of the four materials in different combinations have been reported to exhibit high reversible capacities and long-life cycles. For that reason, in this study the rGO-SnO2-Fe2O3-TiO2 and rGO-Fe2O3-SnO2-TiO2 ternary nanocomposites were synthesized, characterized and evaluated as anode material in sodium-ion battery half cells. Graphene oxide was synthesized by chemical exfoliation of graphite and coated with layers of SnO2, Fe2O3, and TiO2 metal oxides in different combinations by means of the solvothermal and/or hydrothermal and/or co-precipitation methods. When the synthesized nanomaterial were analyzed with the FTIR, Raman spectroscopy, SEM, TEM, TGA, BET, UV-Vis spectroscopy, and XRD analytical techniques; their physical, chemical and optical properties were positively matched to their pure compounds. The electrochemical performance of the rGO-SnO2-Fe2O3-TiO2 and rGO-Fe2O3-SnO2-TiO2 ternary nanocomposites was evaluated using sodium-ion battery half cells. The half cells consisted of a counter and reference electrode made from sodium metal, 1 M NaClO4/PC electrolyte solution in addition to the ternary nanocomposites as the active material in the working electrodes. The cells were assembled in a nitrogen filled glove box with oxygen and moisture concentration of ≤0.5 ppm and 62 ppm — 69 ppm respectively. The ternary nanocomposites exhibited uncharacteristically low...M.Tech. (Chemistry