Highly Flexible Energy Storage Electrodes Based on In Situ Synthesis of Graphene/Polyselenophene Nanohybrid Materials
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Highly Flexible Energy Storage Electrodes Based on In Situ Synthesis of Graphene/Polyselenophene Nanohybrid Materials Jin Wook Park1 and Jyongsik Jang1 1 School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul, Korea. ABSTRACT A new class of graphene–polyselenophene (PSe) hybrid nanocomposite was successfully synthesized using an in situ synthetic method. The synthesized graphene–PSe nanocomposite exhibited unique properties including a large voltage window, high conductivity, and good mechanical properties. The graphene–PSe nanohybrid reduced the dynamic resistance of electrolyte ions and enabled high charge–discharge rates, thereby enabling high-performance supercapacitance. The results were attributed to synergetic effects between graphene and conducting polymers (CPs), which enhanced charge transport, surface area, and hybrid supercapacitance by combining the properties of electrolytic double-layer capacitors (EDLCs) with those of psedocapacitors. Additionally, a flexible supercapacitor based on the graphene–PSe nanohybrid was successfully demonstrated. To fabricate binder-free supercapacitors, chemical vapor deposition (CVD) and vapor deposition polymerization (VDP) methods were employed. The fabricated all-solid-state supercapacitor exhibited outstanding mechanical and electrochemical performance, even after several bending motions. The novel graphene–PSe nanocomposite material is promising for new energy storage and conversion applications. INTRODUCTION The development of portable, flexible, and lightweight energy-storage devices has attracted attention in a wide range of emerging applications, such as wearable electronics, electronic newspapers, and other devices.[1-2] Supercapacitor, also known as electrochemical capacitors, is one of the most promising energy-storage devices due to their high power, high energy density, and long cycle life.[3-4] Supercapacitors are generally divided into two main classes: electrochemical double-layer capacitors (EDLCs) and pseudocapacitors. In general, EDLCs provide lower energy densities than redox supercapacitors because charge is stored only on the surface area of an active EDLC electrode. In contrast, pseudocapacitors use the entire mass of an electrode. For this reason, recent supercapacitor research has focused on the development of redox-active materials with high specific capacitance and sufficient stability for use in pseudocapacitors. Conducting polymers (CPs) are widely recognized as promising electrode materials due to their high specific capacitance and rapid redox-based charge–discharge behavior.[5-6] Among of those materials, Polythiophene (PT) is the most studied material because of their facile electrochemical synthesis and good chemical stability.[7] However, few examples of its close analogue, polyselenophene (PSe), have been reported. PSe is expected to show various unique properties compared with other conducting polymers, particularly PT, such as lower bandgap, greater polarizability, planarity, an
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