The project, carried out from January 2020 to December 2022, aimed to develop a prototype aluminium‑based battery and to lay the groundwork for its integration into industrial production. The core of the work focused on the preparation and handling of aluminium foil as the active material, the optimisation of cutting, folding and winding processes, and the assessment of the resulting cell structure for safety and performance.
A specialised cutting machine supplied by Frolyt was used to slice aluminium, polymer and copper foils in the 20 µm to 200 µm range. Initial trials revealed that the knives originally in use were worn and produced rough edges, which could lead to short‑circuits in the finished cells. To address this, new precision knives were ordered from the Japanese company JCCE. These knives, made from a harder steel and featuring a finer edge, produced cleaner cuts and reduced the risk of stray metal fragments. The improved edge quality was confirmed by visual inspection and by the absence of short‑circuit incidents during subsequent folding and winding tests.
The cutting process required a minimum foil length of 10 m, but the samples supplied by the Institute for Experimental Physics at the TU Bergakademie Freiberg were only a few centimetres long. Consequently, the foils had to be spliced between additional sheets, increasing handling time and the potential for contamination. After each cutting run, the machine was cleaned to remove any shed material, as the presence of debris could compromise the integrity of the battery. Similar precautions were taken during folding tests, which required a minimum length of 6 m. The folding and winding trials were conducted on the same machines used for cutting, and the resulting wound structures were examined in the incoming laboratory for suitability. The tests demonstrated that the foils could be wound into stable coils, but the process was still time‑consuming due to the need for splicing and cleaning.
The scientific literature consulted during the project covered polymer electrolytes, aluminium anode–organic cathode batteries, and hybrid polymer–aluminium electrolytic capacitors. Key references included works by Schoetz (2017), Bitnec et al. (2019), and patents such as US 7497879 B2 and DE 102016125733 A1. A personal interview with a former employee involved in tantalum‑capacitor manufacturing provided additional practical insights into capacitor production.
Collaboration was central to the project. Frolyt Kondensatoren und Bauelemente GmbH supplied the aluminium foils, performed the cutting, folding and winding operations, and managed the project’s day‑to‑day execution. The Institute for Experimental Physics at the TU Bergakademie Freiberg supplied foil samples, conducted mechanical tests, and evaluated the wound structures. Rovak and Filk received additional foil samples, although their results were not shared with Frolyt. Wilhelm Bilstein GmbH & Co. KG, a long‑time partner of Frolyt, provided knife sharpening services and supplied the initial set of cutting knives. The Japanese firm JCCE supplied the precision knives that improved the cutting quality. Funding was provided for the years 2021 and 2022, covering material costs, personnel, and the procurement of new knives; no funding was received in 2020.
By the end of the project, a functional prototype aluminium battery had been assembled, and the key process steps—cutting, folding, winding—had been demonstrated on a laboratory scale. However, the project did not deliver the detailed information required to design and build an industrial‑scale production machine, and the prototype remained a proof of concept rather than a ready‑for‑manufacturing solution.