Metal-Organic Framework-Derived NiS₂ Nanoflowers Supported on Carbon Nanotube Fibers for Aqueous Rechargeable Nickel-Zinc Batteries

The flourishing progression of flexible and wearable electronics has driven the ever-growing demand for high-performance fiber-based energy-storage devices. Meanwhile, metal-organic frameworks (MOFs) with high specific surface area and porosity are promising to act as the precursors and templates for high-performance battery’s materials. Herein, MOF-derived NiS₂ nanoflower arrays (NFAs) grown on carbon nanotube fibers (NiS₂ NFAs/CNTFs) were successfully demonstrated to be the cathodes for advanced fiber-shaped aqueous rechargeable (FAR) Ni//Zn batteries. Density functional theory simulation results confirmed that the introduction of sulfur significantly decreased the band gap, achieving an increased conductivity of the materials. Benefiting from the involvement of sulfur and preserved array morphology, at a current density of 4 mA cm^-2, the NiS₂ NFAs/CNTF electrode can exhibit an extraordinary capacity of 0.45 mAh cm^-2 and an ultrahigh discharge plateau of up to 0.41 V. Additionally, the assembled FAR Ni//Zn batteries deliver an energy density of 219.6 mWh cm^-3 at a power density of 2.4 W cm^-3 and a significant long-term cycling stability. This approach affords some innovative opinions for the design of electrode materials from the aspect of MOF derivatives via restructuring and modification for high-performance energy-storage devices.