Chemical Preintercalation of H 2 V 3 O 8 ‐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 2 V 3 O 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 2 V 3 O 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 2 V 3 O 8 ) at a practical current density of 100 mA ⋅ g −1 , demonstrating that H 2 V 3 O 8 is a promising cathode material for SIBs and LIBs.