Rational construction of porous marigold flower-like nickel molybdenum phosphates via ion exchange for high-performance long-lasting hybrid supercapacitors

Abstract

Recently, many development efforts towards energy storage materials by researchers have resulted in the design and fabrication of various electrode materials for efficient energy storage applications. Transition metal phosphates have attracted much interest among the reported materials due to their superior properties. Herein, we report urea-based nickel molybdenum phosphate nanopetals embedded microspheres (UNMP NPs@MSs) with a morphology closely resembling a marigold flower via an ion exchange synthesis technique. The addition of phosphorus leads to the procedural enhancement of transition metal oxides. Furthermore, this work also specifies the necessity of a suitable morphology to push the working material to its maximum limit. In a three-electrode configuration, the UNMP NPs@MSs-coated nickel foam (UNMP NPs@MSs/NF) electrode delivers an areal capacity value of 166.6 μAh cm⁻², accompanied by a capacity retention of 99.5% after 50 000 cycles. Additionally, the hybrid supercapacitor (HSC) device is assembled with UNMP NPs@MSs/NF as a positive electrode and activated carbon as a negative electrode. The HSC device exhibits an areal capacitance value of 453.95 mF cm⁻² with energy and power density values of 34.34 Wh kg⁻¹ and 5106.38 W kg⁻¹, respectively. Remarkably, the as-assembled HSC shows outstanding long-term cycling stability with 109% retention even after the completion of 100 000 cycles. Finally, the fabricated HSC device is employed to power electronic components to verify its real-time utilization and the results are reported.