Synthesis and capacitive properties of two-dimensional organic-inorganic hybrid frameworks

Abstract

Due to the large variety and unique physiochemical properties, such as high electrical conductivity, adjustable interlayer spacing, intercalation chemistry and so on, two-dimensional (2D) materials have attracted tremendous attention for their suitability in the development of high-performing supercapacitors. Despite that great progress has been made, there is still no single 2D material that can perfectly meet all the requirements to replace the existing material, mainly activated carbon, used in commercial supercapacitors. Therefore, continuing efforts for exploring novel, high-performing 2D materials with low cost are desirable. In this dissertation, the prior studies on the development of 2D materials ranging from layered inorganic materials to organic-inorganic hybrids for supercapacitors are first reviewed. As an emerging type of 2D material, layered organic-inorganic hybrids start to show promising results to be used to fabricate high-density, nonporous, and thick electrodes for compact capacitive energy storage. However, the studies in this area are still lacking. Thus, the goal here is to explore the opportunities of 2D organic-inorganic hybrids for applications in supercapacitors. The relevant techniques and methods used throughout the study are then outlined. Next, three research chapters supporting the main findings of the investigation are included. The first research chapter describes a facile mechanical strategy to improve the kinetics and rate performance of 2D organic-inorganic hybrid electrodes at ultrahigh mass loadings (up to 30 mg cm-2). The second research chapter reports the synthesis of a new layered organic-inorganic hybrid material with excellent volumetric and areal capacitances even at mass loadings reaching 50 mg cm-2, highlighting the good electrode kinetics. The third research chapter presents the wafer-scale electrochemical deposition synthesis of 2D organic-inorganic composite films with controlled size and thickness, which are promising for the development of flexible and transparent electrochemical energy storage devices. Finally, conclusions and recommendations are given at the end of this dissertation.