Highly controlled nanoporous Ag electrode by vaporization control of 2‑Ethoxyethanol for a flexible supercapacitor application

Fine-tuning the surface morphology of the electrode on the nanoscale has attracted much attention in various fields, because the surface morphology of a material allows the functionalization in diverse areas of studies. In... [ view full abstract ]

Fine-tuning the surface morphology of the electrode on the nanoscale has attracted much attention in various fields, because the surface morphology of a material allows the functionalization in diverse areas of studies. In this study, we report a simple and cost-effective process to control the surface morphology and fabricate controlled nanopores on the silver electrode by employing 2-ethoxyethanol and two successive heat treatments. Varying a couple parameters, concentration of 2-ethoxyethanol in Ag organometallic ink and annealing temperature, serves to control the size, depth and morphology of nanopores. As a proof-of-concept, a high-performance supercapacitor was fabricated based on nanoporous silver electrode by electrodepositing MnO2.

To analyze the surface morphology, we utilized SEM and AFM characterization, and XRD confirmed the absence of oxidation in nanoporous silver. After electrodepositing MnO2 on NPS, various electrochemical examinations such as cyclic voltammetry, galvanostatic charge−discharge measurement, and electro- chemical impedance spectroscopy were conducted to investigate the practicality of device. High electrical conductivity and mechanical robustness of nanoporous silver, which were examined with four-point probe test and bending test respectively, substantiate its prospect to be utilized in a variety of applications demanding a certain extent of flexibility. A supercapacitor was fabricated to illustrate the potential practicality of the silver nanoporous electrode herein. The energy density and specific capacitance of supercapacitor based upon the silver nanoporous electrode was measured to be 19.8Wh/kg and 327F/kg respectively at scan rate of 1mV/s. This value was almost three times higher than that of supercapacitor without any pore.

The results demonstrate a simple and economical method to highly control the surface morphology and create nanopores on the Ag electrode. This method is expected to be employed not only in energy storage device but also in other fields by developing a certain surface morphology suitable for each electronic application.