Electrodeposition of the MnO2 on the Ag/Au Core-Shell Nanowire and Its Application to the Flexible Supercapacitor.

Wonbin Seo,Dongwoo Kim,Shihyeong Kim,Habeom Lee

doi:10.3390/ma14143934

Abstract

Supercapacitors have received considerable attention as energy storage devices owing to their high power density, fast charge/discharge rate, and long cyclic life. Especially with an increasing demand for flexible and wearable devices, research on flexible supercapacitors has surged in recent years. The silver nanowire (Ag NW) network has been used as a flexible electrode owing to its excellent mechanical and electrical properties; however, its use as an electrode for flexible supercapacitors has been limited due to insufficient electrochemical stability. In this study, we proposed a method to resolve this issue. We employed a solution process that enabled the coating of the surface of Ag NW by a thin Au shell of ≈ 5 nm thickness, which significantly improved the electrochemical stability of the Ag NW network electrodes. Furthermore, we confirmed for the first time that MnO2, which is one of the most widely used capacitive materials, can be directly electroplated on the AACS NW network electrode. Finally, we fabricated a high-performance and flexible solid-state supercapacitor using the suggested Ag/Au/MnO2 core–shell NW network electrodes.

Highlights

Supercapacitors are energy storage devices that exhibit a high power density, fast charge/discharge rate, and long cyclic life; they have received considerable research interest [1,2,3,4]
The Ag/Au core–shell NW (AACS NW) were prepared by an Au layer coating on the surface of commercial Ag NWs (20 nm in diameter, 20 μm in length)
The prepared Ag/Au/MnO2 core–shell NW electrode exhibited excellent capacitive properties (4.3–12.2 mF/cm2 ) and a fast charge–discharge rate in Na2 SO4 aqueous electrolyte, which was mainly due to the adequate electrical connection between the NW network and MnO2 nanostructures

Summary

Introduction

Supercapacitors are energy storage devices that exhibit a high power density, fast charge/discharge rate, and long cyclic life; they have received considerable research interest [1,2,3,4]. The most basic components of energy storage devices such as supercapacitors are a current collector, a passage for electrons, and an active layer capable of storing electrical energy. In some cases of electrical double-layer capacitors (EDLCs), one electrode simultaneously serves as both the current collector and the active layer. In the most cases of pseudocapacitors, which can achieve a larger storage capacity based on reversible redox reactions, the current collector and active layer are clearly distinguished. The fabrication of a flexible supercapacitor with high storage capacity requires the flexible electrode as a current collector and a technique capable of applying an active layer on the electrode. Pseudocapacitors have a higher energy storage capacity than EDLCs due to their energy storage mechanisms based on reversible redox reactions [17,18,19] in the active layer. There are some limitations to depositing MnO2 on the Ag NW network using the electroplating process, because the electrochemically unstable Ag NWs are damaged during the electroplating process

Methods

Results

Conclusion