NiFeZnP Nanosheets with Enriched Phosphorus Vacancies for Supercapattery Electrodes

Designing and fabricating outstanding electrode materials via simple preparation routes are viable ways for improving the performance of electrochemical supercapacitors. We report on the synthesis of NiFeZn phosphide interconnected nanosheets with abundant phosphorus vacancies (P v -NiFeZnP) via a facile reduction route at room temperature. The fabricated P v -NiFeZnP was fully characterized using energy-dispersive spectroscopy, field emission scanning electron microscopy, electron paramagnetic resonance, and X-ray photoelectron spectroscopy techniques. Owing to the porous interconnected nanosheet structure and the superior stability enabled by the direct binder-free growth on Ni foam, the P v -NiFeZnP electrode, with optimized phosphorus vacancy formation, exhibits a superb electrochemical performance of 631.8 mC/cm 2 (equivalent to 1579.5 mF/cm 2 ), which is significantly higher than those reported in the literature. Also, the P v -NiFeZnP||activated carbon asymmetric device exhibits a very high Coulombic efficiency (∼100%) and excellent long-term stability (98.8% capacity retention after 7500 cycles). The fabricated device can deliver 122.1 μWh/cm 2 energy density at a power density of 750 μW/cm 2 . The fabricated NiFeZnP electrode is therefore a promising candidate for supercapacitor applications.