Super-conductive silver nanoparticles functioned three-dimensional Cu_xO foams as a high-pseudocapacitive electrode for flexible asymmetric supercapacitors

Highlights

• Cu_xO nanowires are vertically grown on Cu foam via a facile surface oxidation.

• Ag nanoparticles are then decorated Cu_xO nanowires via a replacement reaction.

• The electrode shows a maximum specific capacitance of 1192 mF cm⁻² at 2 mA cm⁻².

• The contribution ratio of pseudocapacitance for capacitive process is discussed.

• A 2V LED is lighted up for 90 s by two ASC in series.

Abstract

Copper oxide has aroused great concern in energy storage fields due to its properties of high theoretical capacitance, low cost and mild toxicity. However, its wide application still remains challenges owing to its poor electrical conductivity and unstable cycling life. Binder-free foam electrodes possess abundant porous structures and high specific surface area, which could get good contact with electrolyte. Herein, we demonstrate Ag nanoparticles decorated Cu_xO nanowires grown spontaneously on copper foam (CF) electrode for asymmetric supercapacitor. The skeleton structure of CF provides large amounts of active sites for the growth of Cu_xO nanowires. Moreover, Ag nanoparticles further decrease the internal resistance and enhance the electrochemical performance. Ag/Cu_xO/CF-40 electrode presents a high area specific capacitance of 1192 mF cm⁻² at 2 mA cm⁻² and the influence of surface capacitance-dominated process and diffusion-controlled process are discussed in detail. Besides, the energy density of the as-prepared asymmetric supercapacitor (ASC) reaches 46.32 μWh cm⁻² at a power density of 3.00 mW cm⁻². A 2V LED is lighted successfully by two ASC in series. This work provides a new strategy to prepare low internal resistance and binder-free flexible Ag/Cu_xO/CF electrode, which demonstrates a good potential application in flexible supercapacitors or other wearable electronic devices.