Rapid preparation of nickel fluoride motif via solution-free plasma route for high-energy aqueous hybrid supercapacitor

Abstract

New and more accurate nano-material fabrication technologies are necessary to tackle the limitations of a conventional solution-based synthesis procedure for an efficient, sustainable, and carbon-free energy future. We devised a rapid, room-temperature yet solution-free dry carbon tetrafluoride (CF4) plasma strategy to cultivate the self-assembled nickel fluoride (NiF) motif nanostructure for a high-energy hybrid supercapacitor (HSC). The high reactivity of the CF4 plasma permitted the low temperature and rapid foundation of the NiF motif directly on the 3D Ni foam. The developed NiF motif nanostructure on the Ni foam delivers high electrochemical activity in terms of the specific capacity (1.18 mAh/cm2 at 1 mA/cm2), cycling stability (89.58 % retentions over 10,000 cycles), and rate capability (84.22 % at 10 mA/cm2) in conventional aqueous electrolytes. The ordered growth of the NiF motif nanostructure linked with high fluorine concentration (51.33 at%) provides large electroactive accessible sites and high electronic conductivity for the facial and reversible charge transport process. To further explore the potential of the NiF motif nanostructure, an aqueous HSC cell was assembled by using the NiF motif and activated carbon (AC) as positive and negative electrodes, respectively. The constructed NiF//AC HSC brings an energy density of 0.96 mWh/cm2 at a specific power of 3.18 mW/cm2 with excellent cycling durability (87.98 % over 12,000 cycles) and rate capability (84.55 %). The superior electrochemical parameters of the NiF motif and developed HSC cell indicate that the described synthetic approach can be extended to prepare a wide range of electrode materials rapidly and solution-free dryly.