WP1 Plasma chemical etching for c-Si photovoltaics
    WP3 Structuring of TCO layers for TF-Photovoltaics
    WP5 Infection control: Process and Materials studies
    WP7 Energy storage – Process and materials R&D
    WP9 Interface technologies for durable adhesion
    WP11 Cross-cutting equipment development

Double layer capacitors (DLCs) are seen as key components for energy storage systems, e.g. for economic hybrid electric vehicles. Due to their high power density and outstanding cycle stability, as compared to batteries, DLCs are advantageous in applications like energy recuperation from braking. However, comparatively low energy density and high costs limit their application and performance improvement is required. Within various possible electrode materials, vertical aligned carbon nanotubes are expected to provide many advantageous properties towards next generation DLCs due to their unique structure and their electrical properties. Only their costly production and unsuitable substrates (most used: silicon wafer) are limitations for a broad application. Therefore, the main objective of this WP is the development of economic growth processes for aligned carbon nanotubes on metal electrode surfaces.  Further objectives are the development of dedicated catalyst seed layer with controlled 3D nano-structure to stimulate growth of high aspect conducting CNT material and the development of electrochemical cell configurations with high dual layer capacity, energy density and power density.



The main achievements of the first 18 month work include the development of facile and scalable deposition methods. Nanostructured catalytic thin films were deposited by a chemical solution dip coating process and CNT growth was performed in a thermal atmospheric pressure CVD reactor. Both methods could be adjusted and transferred to metallic substrates, such as stainless steel and nickel foils and also carbon based substrates such as carbon cloth and paper. As a result dense films of vertical aligned CNT on metal foils with a height of up to 120 mm were obtained. A sandwich-cell was designed for the measurements of the electrochemical performance and first results from cyclic voltammetry and impedance spectroscopy indicate a significant contribution of the CNTs on the dual layer capacitance which lead to substantially improved power density.