TY - THES

T1 - Synthesis and characterization of novel carbon-based nanoporous materials for energy storage applications

AU - Natter, Nikolas Rupert

N1 - embargoed until null

PY - 2020

Y1 - 2020

N2 - Rapid population growth and an increased desire for goods and comfort will lead to a strong increase of worlds energy consumption over the next decades. To overcome this challenge, existing energy systems need to become more efficient and new even more efficient technologies have to to be discovered. A very promising group of energy storage devices are supercapacitors due to their high energy output and long life-cycles. A supercapacitor consists of two electrodes that feature ultrahigh surface areas. The most common material for these applications is activated carbon. Recent studies emphasized the use of activated carbon cloth (ACC) that combines the advantages of activated carbon (e.g. high surface area) with the advantages of a cloth (i.e. flexibility and elasticity). Polymer-derived ceramics (PDCs) have been the subject of considerable research due to their performance properties such as extraordinary resistance towards oxidation and creep even at ultrahigh temperatures and their low energy consumption during synthesis. Depending on the chosen synthesis route, PDCs can show several other interesting characteristics such as catalytic or nanoporous properties. Therefore, by combining PDCs with ACC it could be possible to obtain nanocomposites (i.e. composites where at least one phase shows dimensions on the nanometric scale) that are very well suited for energy storage applications such as hydrogen storage or as electrodes in supercapacitors. In this thesis, a laboratory synthesized ACC and a commercially available ACC have been impregnated with different PDCs. The PDCs consist of polysilazane that was mixed with different organometallics in toluene reflux in different ratios. Subsequent pyrolysis transformed the impregnated cloths into the final nanocomposites. Several characterization methods were used along the fabrication process to study the microstructural and morphological changes. Electrochemical studies were carried out to check the suitability of the created nanocomposites for energy storage applications. Porosity studies were performed to link the electrochemical performance to the porosity properties of the material. It was found that the specific surface area as well as the total pore volume decreased compared to the pure ACC. This is attributed to potential pore blocking as a result of the impregnation process. The impregnation route also led to a very inhomogeneous impregnation. The electrochemical studies indicate that the produced nanocomposites are not suitable as electrodes for supercapacitors as a result of a decreased hysteresis loop (i.e. energy storage capability).

AB - Rapid population growth and an increased desire for goods and comfort will lead to a strong increase of worlds energy consumption over the next decades. To overcome this challenge, existing energy systems need to become more efficient and new even more efficient technologies have to to be discovered. A very promising group of energy storage devices are supercapacitors due to their high energy output and long life-cycles. A supercapacitor consists of two electrodes that feature ultrahigh surface areas. The most common material for these applications is activated carbon. Recent studies emphasized the use of activated carbon cloth (ACC) that combines the advantages of activated carbon (e.g. high surface area) with the advantages of a cloth (i.e. flexibility and elasticity). Polymer-derived ceramics (PDCs) have been the subject of considerable research due to their performance properties such as extraordinary resistance towards oxidation and creep even at ultrahigh temperatures and their low energy consumption during synthesis. Depending on the chosen synthesis route, PDCs can show several other interesting characteristics such as catalytic or nanoporous properties. Therefore, by combining PDCs with ACC it could be possible to obtain nanocomposites (i.e. composites where at least one phase shows dimensions on the nanometric scale) that are very well suited for energy storage applications such as hydrogen storage or as electrodes in supercapacitors. In this thesis, a laboratory synthesized ACC and a commercially available ACC have been impregnated with different PDCs. The PDCs consist of polysilazane that was mixed with different organometallics in toluene reflux in different ratios. Subsequent pyrolysis transformed the impregnated cloths into the final nanocomposites. Several characterization methods were used along the fabrication process to study the microstructural and morphological changes. Electrochemical studies were carried out to check the suitability of the created nanocomposites for energy storage applications. Porosity studies were performed to link the electrochemical performance to the porosity properties of the material. It was found that the specific surface area as well as the total pore volume decreased compared to the pure ACC. This is attributed to potential pore blocking as a result of the impregnation process. The impregnation route also led to a very inhomogeneous impregnation. The electrochemical studies indicate that the produced nanocomposites are not suitable as electrodes for supercapacitors as a result of a decreased hysteresis loop (i.e. energy storage capability).

KW - Activated carbon cloth

KW - Characterization

KW - Energy storage

KW - Nanocomposites

KW - Polymer-derived ceramics

KW - Supercapacitor

KW - Activated carbon cloth

KW - Charakterisierung

KW - Energiespeicher

KW - Nanokomposite

KW - Polymer-derived ceramics

KW - Superkondensatoren

M3 - Master's Thesis

ER -