Eco-friendly synthesis of vanadium metal-organic frameworks from gasification waste for wearable Zn-ion batteries

To meet the ever-increasing energy storage demands, there is an urgent need for developing next-generation batteries with high energy densities from an eco-friendly and sustainable resource. Vanadium metal-organic frameworks (V-MOFs) are regarded as important electrode materials for aqueous Zn-ion batteries (ZIBs) due to their large specific surface areas, synthetic tenability, and high theoretical capacities. However, V-MOFs usually suffer from vanadium-induced toxicity and poor cation diffusivities, limiting their practical applications in ZIBs. Herein, an eco-friendly strategy is demonstrated to extract toxic vanadium from gasification waste to synthesize various vanadium oxides, which are the essential precursors for V-MOFs. By screening 11 V-MOF candidates through molecular dynamics simulation, MIL-47 was selected for the waste-derived synthesis because of its facile Zn²⁺ de-/intercalation. The waste-derived MIL-47 with cone-like microstructures is directly grown on a carbon nanotube fiber (w-MIL-47@CNT fiber), which can be used as the binder-free cathode for a fiber-shaped ZIB. Our fiber-shaped ZIB delivers high-rate performance (81.0% of capacity retention after 50-time current density increase), an ultrahigh stack volumetric energy density of 82.3 mWh cm^–3, superior cycling performance over 2000 cycles (88.5% retention), and high mechanical stability, all of which meet wearable and portable battery requirements. Finally, life cycle assessments are performed to evaluate the environmental impact of each synthesis/fabrication step across 17 different categories, providing valuable optimization guidelines for producing ZIBs from gasification waste.