Ultrastable Cu Intercalation Chemistry Based on a Niobium Sulfide Nanosheet Cathode for Advanced Aqueous Storage Devices.

Exploring stable and durable cathodes for cost-effective reversible aqueous batteries is highly desirable for grid-scale energy storage applications, but significant challenges remain. Herein, we disclosed an ultrastable Cu intercalation chemistry in mass-produced exfoliated NbS nanosheets to build ultralong lifespan aqueous batteries with cost advantages. Anisotropic interplanar expansion of NbS lattices balanced dynamic Cu incorporation and the highly reversible redox reaction of Nb/Nb couple were illuminated by operando synchrotron X-ray diffraction and energy dispersive X-ray absorption spectroscopy, affording an extraordinary capacity of approximately 317 mAh g at 1 A g and a good stability of 92.2% capacity retention after 40000 cycles at 10 A g. Impressively, a budget NbS||Fe hybrid ion cell involving an aqueous electrolyte/Fe-metal anode is established and provides a reliable energy supply of 225.4 Wh kg at 750 W kg, providing insights for building advanced aqueous battery systems for large-scale applications.