Synthesis of Vanadium‐Incorporated, Polyoxometalate‐Based Open Frameworks and Their Applications for Cathode‐Active Materials

The tuning of the chemical composition of polyoxometalate (POM)-based open framework materials with the same structure, leading to a property change of the materials, is interesting. Here, we report the synthesis of a series of vanadium-incorporated, ϵ-Keggin polyoxometalate-based open framework materials by using a hydrothermal method. The resulting materials were characterized by powder X-ray diffraction, FTIR spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis. Our results indicate that V is successfully incorporated into the frameworks of the materials. The introduced amount of V can be adjusted by controlling the addition of the precursor V compounds. The performances of these materials as cathode materials for Li-ion batteries have been tested. Incorporation of V can improve the cycle performance. After the 20th cycle of the charge–discharge process, the materials were transformed to the Li2MoO4 phase.