The 28th New Dresden Vacuum Technology Colloquium (NDVaK) on 5 and 6 October 2022 in Dresden focused on "Coating, Modification and Characterization of Polymer Surfaces" with a focus on "Surface Technologies for the Energy Transition". Four of the 20 presentations were canceled due to illness. The time was used by the 40 or so participants for in-depth discussions.
In addition to the long-standing organizers Leibniz-Institut für Polymerforschung Dresden e.V. (Dresden), Europäische Forschungsgesellschaft Dünne Schichten e.V. (Dresden) and Deutsche Forschungsgesellschaft für Oberflächenbehandlung e.V. (Neuss), Creavac GmbH (Dresden) and Coating Consulting (Markkleeberg) played a key role in the organization of the event. With presentations on material efficiency, energy saving, conversion and storage with the aid of surface technologies, the colloquium aims to contribute to shaping the energy transition, preferably towards the use of naturally renewable energy sources, which has become even more urgent in the recent past. This applies to both atmospheric and vacuum-based processes.
Based on the results of studies, e.g. for the VCI, Andreas Holländer (Fraunhofer IAP, Potsdam) uses the actual and expected energy demand in Germany up to 2050 to illustrate the problem of a possible supply gap in the course of the energy transition. Meeting the demand and either neutralizing, reducing or even avoiding greenhouse gas emissions, especiallyCO2 emissions, is of the highest economic relevance. He poses the question: What can surface technologies do to achieve this and names fields of application such as construction glass coating, the generation and storage of renewable energy, wear and corrosion protection, energy saving and resource conservation. TheCO2 footprint of vacuum technology processes will be discussed.
Konstantin Livanow (OrelTech GmbH, Berlin) will present the company's range of services and describe the deposition of functional residue-free metal layers (silver, gold, palladium, iridium; possibly also others) from 30 to 2000 nm by plasma hardening of layers of self-developed nanoparticle-free metallization liquids in low-pressure argon plasma. This innovative process is a promising alternative to electrochemical and vacuum processes for almost any substrate material and substrate design (e.g. also powders and foams), especially for temperature-sensitive substrates. Compared to electrochemical and vacuum processes, the equipment and material costs are lower and save up to 95% process energy. Successful applications include printed electronics, catalytic and antibacterial coatings, biochips and medical sensors and coating of plastics and textiles. The energy transition requires the provision of green hydrogen from renewable sources far beyond the current level. For water electrolysis, which currently accounts for around 5% of this, gas diffusion, electrode and ion-conducting membrane layers of the stack components must be provided faster and more cost-effectively. Michael Rentzsch (Papiertechnische Stiftung, Heidenau) reports on development results for lignocellulosic-based functional components for PEM water electrolysis. The substrates are functionalized by impregnation, coating and lamination. The highly productive potential of paper production is used for this. The results are also of interest for fuel cells and energy storage (PtX, H2tX).
A similar challenge is the cost-effective production of bipolar plates for fuel cells. In some cases, this is still carried out in individual production with a cost share of up to 30%. One research focus in the H2GO- National Action Plan Fuel Cell Production (start on September 13, 2022) - is increasing productivity and minimizing costs in the coating, forming and joining of stainless steel sheet (1.4404) using the roll-to-roll process. Teja Roch (Fraunhofer IWS, Dortmund) reports on investigations into the suitability of known roll-to-roll processes instead of batch processes. The coatings applied using PVD coil coating with GLC or chromium showed comparable results for contact resistance and corrosion behavior to the gold coatings currently used.
Lisa Ehrlich from the Leibnitz Institute IPF Dresden reported on the synthesis of polymer electrolytes for solid-state batteries. The aim of the work presented is to switch to polymer redox systems as active materials for electrolysis instead of lithium-ion batteries, which have a limited resource potential due to the rare earths required. Polymer systems for suitable polymer electrolytes must be chloride-ion conductive. Such systems, which were produced by means of anionic polymerization and subsequent functionalization via polymer-analogous reactions, have shown that they have the potential to represent a real alternative here. The systems shown have good ionic conductivity and the mobility of the charge carriers also enables the cells to perform well. In addition, the electrolytes are stable in air.
Alexander Plettig (Brandenburg University of Technology Cottbus-Senftenberg) will present the results of the extensive project "Process-integrative production and integration of complex-shaped hybrid multilayer composites with high functional density for rail vehicle construction - HIKOM Pro". In vehicle construction, reducing weight can make a sustainable contribution to saving energy. By combining thermoplastic lightweight cores or fiber-reinforced plastics with thin metal sheets to create function-integrating lightweight elements, the composite has achieved the strength required for variable shaping and specific mechanical stresses (e.g. in rail vehicles).
By means of function-integrative sensor technology in the composite, concepts for localizing the forces that occur can be implemented for material-specific monitoring of the components both in production and in operation in order to ensure maximum safety.
On the one hand, the global increase in plastic waste is a problem; on the other hand, only a fraction of the waste - around 25% in the EU - is recycled, i.e. reprocessed into products. Dirk Hegemann (Empa, Dübendorf) shows that an adapted plasma-guided or plasma-assisted coating of products made from recyclates can contribute to reuse. This immediately raises the question of the reuse of recycled material. Recycled PET can be pre-treated in an Ar/O2 plasma in such a way that it can be metallized with high adhesion. Plasma polymer layers can act as adhesion promoters. Packaging material (e.g. made of polypropylene) can be provided with SiOx-based diffusion barriers and equipped with hydrophobic plasma polymer layers, whereby the layer thickness should also remain below 50 nm due to recyclability. Industrial applications will be discussed together with technological information for atmospheric and low-pressure plasma treatments for recycled and single-origin plastics.
R. Palitzsch (LuxCemtech GmbH, Freiberg) impressively demonstrates how valuable materials can be economically recovered from the thin functional semiconducting and metallic layers in mass-produced electronic products at the end of their service life or from the development phase.
The layer structure in photocells, displays and PCBs, which is usually produced using vacuum technology, poses a particular challenge for reuse. In photocells (e.g. of the CIGS type), the "sandwich structure" is opened thermally (laser) and the semiconductor material is detached from the carrier (glass) using wet chemistry and then cadmium, copper, molybdenum, selenium, indium and gallium are isolated. A similar process is used for LCD displays to obtain ITO, liquid crystal and spacer material. Shredding of the entire composite is also avoided in the case of silicon photovoltaic modules. After separation, silicon (then further processed into targets or SiC), silver, indium, tin and polyalumium chloride [Aln(OH)mCl3n-m] are extracted, depending on the cell type.
Estefania Arrazola Martínez will present standard and customized low-pressure plasma systems from Pink GmbH, Wertheim. After a brief description of the interaction of plasma with a solid surface, in this case with microwave excitation, the energy-saving use of plasma as a substitute or supplement to other treatments for cleaning and etching is discussed using examples. Finally, the consumption of operating materials, gas consumption and costs for an oxygen process are estimated and the advantages of plasma technology are summarized.
Martin Fischer (Pfeiffer Vacuum GmbH) also deals with energy savings in connection with the use of vacuum pumps. He sees potential savings in the drive technology, in the selection of the pump principle and in the setting of the operating mode of the pumps. He demonstrates the former for the rolling bearing pumps in the HiLobe series. With regard to the pumping principle, oil diffusion and turbomolecular pumps as well as process screw pumps and multi-stage roots are compared. Finally, an energy-saving standby can be set up when high pumping capacities are no longer required.
Andreas Holländer (Fraunhofer IAP, Potsdam) addressed the still current problem of adhesive-free bonding of plastics. The functional groups formed by cleaning and activating the bonding partners in a plasma (corona, low pressure) enable covalent formations to form through acceptor-donor interactions. Pressure, temperature and elastic properties determine the achieved strength of the composite. Process parameters, procedure and results are discussed for PMMA-PMMA composites. This adhesive-free bonding also works for PE-PE, PE-PET, PET-ABS and PC-SiO2.
Stefan Saatmann gives an insight into the activities of Siemens AG to make energy generation in Germany greenhouse gas-free by 2050 and to secure the energy supply of private and industrial users, which is endangered by the sanctions on natural gas supplies from Russia, by decentralizing the energy supply and thus contributing to Germany's energy independence and national security. It describes a sustainable energy concept in the Blankenburg Energy Park for the production of green hydrogen using renewable energy and water electrolysis in combination with battery storage. As a technology and implementation partner, Siemens AG is providing holistic project support from analysis and planning to implementation, operation and service. The stakeholders to be involved range from industry and public utilities to municipal decision-makers.
Martin Hager will provide an insight into extensive work on electrodes and electrolytes for fully polymer-based batteries at the Friedrich Schiller University Jena. Among other things, polymer active materials enable the production of thin and flexible batteries that can also be manufactured using printing techniques. In the case of electrolytes, for example, ionic liquids were investigated and printable gel polymer electrolytes were developed.
Philipp Schlee (Skeleton, Großröhrsdorf) provided information on the current and future activities of the German-Estonian company Skeleton Technologies for supercapacitors for energy storage. The first-generation supercapacitors (2017) with graphite electrodes have energy densities of 9.3 Wh/kg with charging times of less than 1 s. The use of bent graphene with significantly smaller pores (less than 1 nm) almost doubles the energy density (second-generation supercapacitors, from 1923 in Markranstädt). Superbatteries with 65 Wh/kg and charging times of less than 60 s are expected for 2024. With these energy storage systems up to the MWs range, the entire traffic and transportation system can be brought closer to the set goal of zero-emission electrification.
Transparent conductive oxides (TCO) such as indium oxide (In2O3), tin oxide (SnO2), zinc oxide (ZnO) or titanium oxide (TiO2) are also of interest for solar cells. Klaus Ellmer (OUT e. V., Berlin) describes for In2O3 how doping with hydrogen (IO:H) and annealing at more than 160 °C can increase the electron mobility to over 100 cm2/Vs. The deposition is carried out by reactive magnetron sputtering at a water partial pressure of up to 8.10-2 mbar. The lower grain boundary scattering due to the recrystallization of the amorphously deposited indium oxide by annealing the grains formed at more than 160 °C (lateral dimension up to 700 nm at 100 nm layer thickness) is essential for the resulting properties. The hydrogen acts as a donor. The high mobilities are achieved at a few 10-2 mbar and a hydrogen content of around 5 at-%.
Great efforts are being made worldwide to replace lithium-ion batteries with more powerful and safer solid-state batteries in the future. Christoph Tammer (Fraunhofer IGCV, Braunschweig) explains the ongoing Di-BATMA-pro project. It aims to demonstrate that the development times for battery materials and new cell technologies can be significantly reduced with the help of digitalized process chains in the synthesis of battery materials, laboratory and pilot production of solid-state cells, high-throughput testing of the cells and recycling, and with the help of automated processes and a sophisticated digital infrastructure. A pilot line for the production of solid-state cells with polymer solid electrolyte is described in detail.
Figure 2: Biogas plant with Heliatek solar films, Pfaffenhofen/Germany
Karsten Walzer introduces the Dresden-based company Heliatek GmbH, which now has 200 employees, as a pioneer in the field of organic layers for solar energy and as an innovation leader in optical photovoltaics. Thin, flexible organic solar films (HeliaSol) are produced on the basis of a layer structure developed in-house using organic semiconductors vapor-deposited in a high vacuum. These films are also the perfect solution for retrofitting and integrated products and are available in customer-specific sizes, colors and degrees of transparency. Finally, globally realized applications of the first truly clean solar technology with a carbon footprint below 10gCO2e/kWhwill be shown - see Figure 1 and Figure 2.
In an evening event, Claudia Hinz ("weather fairy" on the Wendelstein in Upper Bavaria) will delight the audience in an endearingly humorous way with her lecture "From rainbow to aurora borealis" with a large number of her own photos of atmospheric light phenomena taken in her home environment.
