Pseudocapacitance Powered Nickel Molybdenum Nitride Nanocomposite Reactively Cosputtered on Stainless-Steel Mesh toward Advanced Flexible Supercapacitors

Ternary transition metal nitrides are emerging pseudocapacitive materials for the development of high-energy-density flexible supercapacitors. The present report demonstrates a facile, scalable, and binderless fabrication of unique nickel molybdenum nitride (Ni-Mo-N) nanocomposite directly on stainless-steel mesh (SSM) via reactive magnetron cosputtering technology for flexible symmetric supercapacitor (FSSC) application. Benefiting from the advanced synergism between multiple integrated phases, the ternary Ni-Mo-N/SSM electrode exhibits highly pseudocapacitive characteristics and delivers a maximum specific capacitance of ∼43.11 mF cm–2 in comparison to pristine Ni3N/SSM (∼2.32 mF cm–2) and Mo2N/SSM (∼34.94 mF cm–2) electrodes. An extensive b-value and Dunn's investigation reveal the dominance of surface-limited capacitive and pseudocapacitive mechanisms over diffusion-limited redox processes at the Ni-Mo-N nanocomposite. The as-assembled FSSC device (Ni-Mo-N/SSM||Ni-Mo-N/SSM) attains an impressive cell capacitance of ∼37.89 mF cm–2 (or 229.64 F g–1) at 0.15 mA cm–2 together with remarkable cycling performance, retaining ∼95.12% capacitance after 10,000 continuous galvanostatic charge–discharge (GCD) cycles. Moreover, the FSSC renders a superior combination of high energy, ∼4.26 μWh cm–2 (or 25.83 Wh kg–1), and power density, ∼1.07 mW cm–2 (or 6.50 kW kg–1), while displaying state-of-the-art stable flexibility, maintaining ∼95.3% and ∼94.5% capacitance after 1500 GCD cycles at +90 and −90° bending angles, respectively. Therefore, the current fabrication strategy of reactively cosputtering a Ni-Mo-N nanocomposite presents a promising avenue for developing high-energy-density and ultrastable flexible supercapacitors.