摘要
Affordable energy storage is crucial for a variety of technologies. One option is sodium-ion batteries (NIBs) for which, however, suitable anode materials are still a problem. We report on the application of a promising new class of materials, polyoxometalates (POMs), as an anode in NIBs. Specifically, Na 6 [V 10 O 28 ]·16H 2 O is being synthesized and characterized. Galvanostatic tests reveal a reversible capacity of approximately 276 mA h g -1 with an average discharge potential of 0.4 V vs. Na/Na + , as well as a high cycling stability. The underlying mechanism is rationalized to be an insertion of Na + in between the [V 10 O 28 ] 6- anions rather than an intercalation into a crystal structure; the accompanying reduction of V +V to V +IV is confirmed by X-ray Photoelectron Spectroscopy. Finally, a working full-cell set-up is presented with the POM as the anode, substantiating the claim that Na 6 [V 10 O 28 ]·16H 2 O is a promising option for future high-performing sodium-ion batteries.