Chemical Preintercalation of H2V3O8-reduced Graphene Oxide Composites for Improved Na- and Li-ion Battery Cathodes

Due to a growing demand for sustainable electrical energy storage alternatives to Li-ion batteries (LIBs), Na-ion batteries (SIBs) are of great interest because of the abundance of Na ⁺. By modifying layered H ₂V ₃O ₈ by preintercalation and composite formation, improved electrochemical properties were obtained in LIBs. In analogy, a scalable soft chemistry synthesis is developed, to chemically presodiate H ₂V ₃O ₈ for the first time, in addition to a composite formation reaction with reduced graphene oxide (rGO). Crystal structure and morphology of all compounds are determined and their electrochemical properties as cathode are evaluated with respect to both Na ⁺ and Li ⁺ intercalation. The combination of preintercalation and composite formation leads to excellent initial capacities of 96 mAh ⋅ g ⁻¹ for SIBs and 371 mAh ⋅ g ⁻¹ for LIBs (58 % and 48 % higher than unmodified H ₂V ₃O ₈) at a practical current density of 100 mA ⋅ g ⁻¹, demonstrating that H ₂V ₃O ₈ is a promising cathode material for SIBs and LIBs.