Controlled synthesis of FeCo2O4@NiMoO4 core-shell nanostructures as a binder-free electrode for high-performance asymmetric supercapacitor with enhanced density and rate capability

FeCo 2 O 4 @NiMoO 4 /NF composites were synthesized by two-step hydrothermal method. • The core-shell nanosheet structure offers abundant active sites and ion diffusion. • The electrode delivers a high surface capacitance of 5210 mF cm −2 at 1 mA cm −2 . • An asymmetric supercapacitor achieves an extended voltage window of 1.7 V. • FeCo 2 O 4 @NiMoO 4 /AC supercapacitor achieves excellent energy density of 0.27 mWh cm −2 . The development of binder-free electrodes is critical for advancing high-performance supercapacitors, yet achieving both high areal capacitance and long-term stability remains a challenge. Herein, the core-shell FeCo 2 O 4 @NiMoO 4 /NF (FCO@NMO/NF) composite material was synthesized on nickel foam by a simple two-step hydrothermal method as the positive electrode for asymmetric supercapacitors. The prepared electrode leverages the advantages of porous nanosheets' abundant reactive sites and multimetallic synergistic effects. Consequently, the FCO@NMO/NF electrode delivers an exceptional areal capacitance of 5210 mF cm −2 at 1 mA cm −2 , which is 4.5 times higher than that of the pristine FeCo 2 O 4 electrode. Furthermore, an assembled asymmetric supercapacitor (ASC) with FCO@NMO/NF and activated carbon electrode (AC/NF) achieves a wide voltage window of 1.7 V, a high energy density of 0.27 mWh cm −2 , and outstanding cycling stability with 97.4% capacitance retention after 6500 cycles. Overall, the FCO@NMO/NF is a promising binder-free electrode material for next-generation energy storage devices. Download: Download high-res image (223KB) Download: Download full-size image