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

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 CuxO 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 CuxO nanowires.Moreover,Ag nanoparticles further decrease the internal resistance and enhance the electrochemical performance.Ag/CuxO/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 mWh 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/CuxO/CF electrode,which demonstrates a good potential application in flexible supercapacitors or other wearable electronic devices.

Tripotassium citrate monohydrate derived carbon nanosheets as a competent assistant to manganese dioxide with remarkable performance in the supercapacitor

Production cost,capacitance,and electrode materials safety are the key factors to be concerned about for supercapacitors.In this work,a type of carbon nanosheets was produced through the carbonization of tripotassium citrate monohydrate and nitric acidification.Subsequently,a well-designed manganese dioxide/carbon nanosheets composite was synthesized through hydrothermal treating.The carbon nanosheets served as the substrate for growing the manganese dioxide,regulating its distribution,and preventing it from inhomogeneous dimensions and severe agglomeration.Many manganese dioxide nanosheets grew vertically on the numerous functional groups generated on the surface of the carbon nanosheets during acidification.The synergistic combination of carbon nanosheets and manganese dioxide tailors the electrochemical performance of the composite,which benefits from the excellent conductivity and stability of carbon nanosheets.The carbon nanosheets derived from tripotassium citrate monohydrate are conducive to the remarkable performance of manganese dioxide/carbon nanosheets electrode.Finally,an asymmetric supercapacitor with active carbon as the cathode and manganese dioxide/carbon nanosheets as the anode was assembled,achieving an outstanding energy density of 54.68 Wh·kg^(−1) and remarkable power density of 6399.2 W·kg^(−1) superior to conventional lead-acid batteries.After 10000 charge-discharge cycles,the device retained 75.3%of the initial capacitance,showing good cycle stability.Two assembled asymmetric supercapacitors in series charged for 3 min could power a yellow light emitting diode with an operating voltage of 2 V for 2 min.This study may provide valuable insights for applying carbon materials and manganese dioxide in the energy storage field.