Item

Abstract

This thesis investigates the potential of carbon xerogel as an electrocatalyst for electrodes and a minor conductive nanofiller for bipolar plates in vanadium redox flow batteries. Spectroscopic, microscopic, and tomographic methods were employed to map the chemical composition and microstructure at different scales in carbon-based nanomaterials and nanocomposites.
The carbonization of resorcinol-formaldehyde-based organic xerogel in an ammonia atmosphere was explored to incorporate nitrogen into the carbon backbone structure. The mechanism of nitrogen doping was elucidated by tracking the structural and chemical transformations in nitrogen-doped carbon xerogels carbonized ex-situ at different temperatures. Results revealed changes in local ordering and chemical structure, including reduced oxidation sites, expansion of sp² carbon network structures, and nitrogen incorporation. Additionally, pyrolysis in ammonia influenced the porous structure, leading to a partial loss of mesopores and increased micropore volume. However, the electrocatalytic property of the studied nitrogen-doped carbon xerogel for the VO₂⁺/VO²⁺ reaction did not significantly improve.
Next, the impact of minor conductive nanofiller on the structure and properties of carbon-polymer composite bipolar plates was assessed using plates with and without commercial carbon black. While carbon black addition enhanced electrical conductivity, its excessive content exacerbated corrosion in bipolar plates, underscoring the importance of carbon nanofiller and, even more, the careful composition selection for achieving desired bipolar plate properties. Lastly, carbon xerogel was introduced as a minor conductive filler in bipolar plates, exhibiting superior conductivity with the potential for even greater improvement, highlighting its suitability as a nanofiller for conductive bipolar plates in vanadium redox flow batteries.