Nanostructured H2V3O8 is a promising high‐capacity cathode material, suitable not only for Li+ but also for Na+, Mg2+, and Zn2+ insertion. However, the full theoretical capacity for Li+ insertion has not been demonstrated experimentally so far. In addition, improvement of cycling stability is desirable. Modifications like substitution or prelithiation are possibilities to enhance the electrochemical performance of electrode materials. Here, for the first time, the substitution of vanadium sites in H2V3O8 with molybdenum was achieved while preserving the nanostructure by combining a soft chemical synthesis approach with a hydrothermal process. The obtained Mo‐substituted vanadate nanofibers were further modified by prelithiation. While pristine H2V3O8 showed an initial capacity of 223 mAh g−1 and a retention of 79 % over 30 cycles, combining Mo substitution and prelithiation led to a superior initial capacity of 312 mAh g−1 and a capacity retention of 94 % after 30 cycles.
Vanadate compounds, such as V3O7·H2O, are of high interest due to their versatile applications as electrode material for metal-ion batteries. In particular, V3O7·H2O can insert different ions such as Li+, Na+, K+, Mg2+ and Zn2+. In that case, well resolved crystal structure data, such as crystal unit-cell parameters and atom positions, are needed in order to determine the structural information of the inserted ions in the V3O7·H2O structure. In this work, fundamental crystallographic parameters, i.e. atomic displacement parameters, are determined for the atoms in the V3O7·H2O structure. Furthermore, vanadium ions were substituted by molybdenum in the V3O7·H2O structure [(V2.85Mo0.15)O7·H2O] and the crystallographic positions of the molybdenum ions and their oxidation state are elucidated.
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 H2V3O8 by preintercalation and composite formation, improved electrochemical properties were obtained in LIBs. In analogy, a scalable soft chemistry synthesis is developed, to chemically presodiate H2V3O8 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 H2V3O8) at a practical current density of 100 mA ⋅ g−1, demonstrating that H2V3O8 is a promising cathode material for SIBs and LIBs.
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