Functional Ceramic Nanostructures and Hybrids from Preceramic Polymer Route for Energy Applications

Abstract

Materials used in advanced functional applications often demand distinct microstructures and morphologies, which can be achieved within single-phase or multi-phase nanostructures. For instance, lithium-ion batteries (LIBs) and supercapacitors—currently the leading energy storage devices—are widely utilized in various equipment of different sizes and purposes. These devices rely on electrode materials with tailored microstructures to achieve improved energy and power density. Consequently, there has been a growing focus on developing innovative material chemistries, morphologies, and nanostructures, particularly among oxides, alloys, and hybrid materials.

Preceramic polymer-derived ceramics (PDC) have emerged as a promising option for next-generation energy technologies. These materials are renowned for their outstanding properties, including high heat resistance, zero creep strain, piezoresistivity, photoluminescence, and their ability to intercalate lithium ions. A key advantage of PDC materials lies in their ability to be processed from liquid precursors, which facilitates the fabrication of materials in various forms. The distinct nanostructure of SiOC materials—comprising SiO₂ nanodomains, graphene-like carbon layers, and mixed-bond tetrahedral regions—offers significant potential for the development of advanced functional materials.

In this presentation, several approaches will be highlighted. Firstly, the fabrication of a porous Si-C nanostructure using a preceramic polymer processing route will be discussed. These hybrid materials, suitable for use as anodes in high-energy-density lithium-ion batteries (LIBs), demonstrate exceptional performance. Specifically, the formation of pores and turbostratic carbon coatings around nanoparticulate Si enables the structure to retain approximately 80% of its initial specific capacity even after 200 charge-discharge cycles. By achieving a more uniform microstructure and better control of the pore space, these materials hold the potential to attain even higher specific capacities. Another approach involves the combination of nanocarbon and SiOC, followed by etching the SiOC matrix to create a highly porous carbon hybrid with a remarkable specific surface area of 1800 m² g⁻¹ and a micropore volume of 0.9 cc g⁻¹. Additionally, the incorporation of transition metals, such as vanadium, enables the utilization of both faradaic and non-faradaic charge storage mechanisms. Cyclic voltammetry studies reveal classical supercapacitive behavior along with redox peaks associated with the reactions of vanadium carbide nanocrystals formed during the pyrolysis of preceramic polymers doped with molecular additives containing transition metals. These composites exhibit remarkable stability, showing no specific capacitance decay even under high current discharge rates.

These examples underscore the versatility of preceramic polymers in processing nanostructures with diverse chemistries. The insights gained pave the way for further exploration of advanced materials using preceramic polymer-based approaches.