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
Aswini Bera, Anirban Maitra, Amit Kumar Das, Lopamudra Halder, Sarbaranjan Paria, Suman Kumar, Anurima De, Suparna Ojha, Bhanu Bhusan Khatua
Abstract
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 (Csp) values of ∼1706.2 and 221.5 F g–1 (at 1 A g–1 current density), respectively, accompanied by an improved retention of their inherent Csp (∼94.4% for NC and ∼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 ∼40.03 Wh kg–1 with a power density of ∼325.4 W kg–1 at 1 A g–1. Noticeably, the ASC retains an energy density of ∼27.2 Wh kg–1 (with a power density of ∼3250 W kg–1) even at 10 A g–1. Moreover, the ASC retains ∼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.