The Cell‑Fill project, carried out by the Technical University of Munich (TUM) from 1 October 2019 to 31 March 2023, was funded by the German Federal Ministry of Education and Research under grant number 03XP0237B. Its central aim was to deepen the scientific understanding of electrolyte filling and wetting in large‑format lithium‑ion batteries and to develop a quantitative, simulation‑based strategy that could reduce the filling time by up to 30 %. The project focused on process‑structure‑property relationships for third‑generation battery materials, innovative cell and process designs, and the identification of material‑level optimisation opportunities.

A key technical outcome was the systematic study of process parameters on pouch and hard‑case cells with diverse material systems. By varying the electrolyte volume in multi‑layer pouch cells, the team demonstrated improvements in both cycle life and energy density, although specific numerical gains were not disclosed in the brief. Crucially, the research established that a wetting degree of 98 % is required for optimal cell performance; this threshold was confirmed through the construction of test cells, electrochemical characterisation, and post‑mortem analysis. The project also produced a comprehensive simulation model that captures the dosing and wetting dynamics across multiple scales. This model, developed in collaboration with Fraunhofer ITWM, enables the derivation of actionable recommendations for process optimisation and has been validated against experimental data.

In addition to the experimental work, the project delivered a set of quantitative models that link process parameters such as pressure and temperature to wetting time and product quality. These models form the basis for a future, time‑ and cost‑optimised filling strategy that can be implemented in industrial production lines. The simulation framework also supports the exploration of novel materials and cell geometries, thereby extending the applicability of the findings beyond the specific cell formats studied.

Collaboration was a cornerstone of the project. The consortium included the Institute for Machine Tools and Operations Science (iwb) at TUM, the Institute of Work and Process Engineering (IWF) at TU Braunschweig, the Mechanical Engineering and Energy Technology (MEET) group at Westfälische Wilhelms‑Universität Münster, and Fraunhofer Institute for Production Technology (ITWM). Experiments on process and cell design were benchmarked against results from the IWF, while electrolyte‑quantity studies benefited from test and analysis methods exchanged with MEET. The Fraunhofer ITWM partnership supplied multi‑scale simulation tools that were integrated into the project’s modelling effort. Outside the core consortium, the team also collaborated with the elania Institute at TU Braunschweig, whose forming plan contributed to a joint publication.

The project’s outputs include several peer‑reviewed publications, conference presentations, and detailed technical reports. It also served as a training ground for doctoral candidates—Dr. Ing. Florian Günter and Jan Hagemeister—who contributed to the research and later defended their theses. Moreover, the Cell‑Fill findings were incorporated into the TUM curriculum through a lecture and a practical course on battery production, engaging roughly 50 students per semester.

Overall, the Cell‑Fill project advanced the scientific knowledge of electrolyte filling and wetting, produced validated simulation tools, and established a collaborative framework that bridges academia and industry. These achievements position Germany as a leading contributor to the global research landscape in battery cell manufacturing.