A Quasi-Solid-State Asymmetric Supercapacitor Device Based on Honeycomb-like Nickel-Copper-Carbonate Hydroxide as a Positive and Iron Oxide as a Negative Electrode with Superior Electrochemical Performances

Here, we have fabricated a high performance asymmetric supercapacitor (ASC) device consisting of honeycomb-like nickel-copper-carbonate-hydroxide (NC) coated stainless steel (SS) as a positive and iron oxide nanoparticle (Fe2O3 NPs) coated SS as a negative electrode, separated by a poly(vinyl alcohol)-potassium hydroxide (PVA-KOH)-based gel membrane. Both of the component electroactive materials were synthesized via substrate free polyvinylpyrrolidone (PVP) assisted facile hydrothermal protocols. The as synthesized NC with numerous interconnected nanoflakes and mesoporous Fe2O3 NPs exhibits superior electrochemical properties. As an outcome, NC and Fe2O3 display specific capacitance (C-sp) values of similar to 1706.2 and 221.5 F g(-1) (at 1 A g(-1) current density), respectively, accompanied by an improved retention of their inherent C-sp (similar to 94.4% for NC and similar to 95.7% for Fe2O3) after 3000 galvanostatic charge-discharge (GCD) cycles at 1 A g(-1). Finally, our assembled ASC device reveals an energy density value of similar to 40.03 Wh kg(-1) with a power density of similar to 325.4 W kg(-1) at 1 A g(-1). Noticeably, the ASC retains an energy density of similar to 27.2 Wh kg(-1) (with a power density of similar to 3250 W kg(-1)) even at 10 A g(-1). Moreover, the ASC retains similar to 88.1% of its original Csp after 10 000 successive GCD cycles. Thus, the ASC device with adequate electrochemical performance is highly promising for portable and flexible electronics.