"The cathode plays a crucial role for the economic success of our battery"

16 January 2025

In this latest feature, we speak with Julian Seiler from the German Aerospace Center (DLR), a key partner in the HIPERZAB project. As a renowned expert in the field of zinc-air battery technology, Julian Seiler and his team at DLR bring advanced methodologies to the development and optimization of gas diffusion electrodes on the cathode side of Electrically Rechargeable Zinc-Air Batteries (ERZABs). Through innovative operando techniques, physical models, and a focus on scalable, sustainable solutions, DLR is making significant strides toward overcoming the challenges of cathode development and electrolyte integration in ERZAB technology. Seiler shares his insights into the critical role of operando techniques and the development of next-generation cathodes that can enable long-term, high-efficiency energy storage.

 

Which operando techniques will you develop?

To generate a deeper understanding of the processes within the zinc-air-battery, we need to combine physical characterization techniques with electrochemical methods and modelling. Also, not only operando technologies, but also ex situ and post mortem methods.

In HIPERZAB, the DLR is mainly focusing on studying the gas diffusion electrode on the cathode side of the battery. We already have quite advanced techniques under development to get insights into its wetting behaviour in liquid electrolyte systems under applied potential that we will further develop in the project. But as we move towards the gel polymer electrolyte system, it becomes even more critical to understand where the reaction zone is located both during charging and discharging to tailor electrode architecture and optimize the distribution of the polymer electrolyte. With FIB-SEM we will analyse the distribution of the gel polymer electrolyte in the gas diffusion electrode. Operando UV-Vis combined with in situ gas analysis in a custom cell setup will help us to assess the stability of the new electrolyte components as a function of the applied potential while with electrochemical impedance spectroscopy we will monitor how the limiting processes in the electrodes and degradation phenomena evolve with cycling. We will work closely together with IREC which is doing material-level studies of the catalyst stability under operating conditions with advanced spectroscopic techniques, namely operando spectroscopic ellipsometry and Raman spectroscopy.

During scale-up of the cell to 100cm² electrode surface at the later stage of the project we want to evaluate optimal cell design and operating conditions. For that purpose, we will adapt our proprietary segmented cell technology to the HIPERZAB specifications and use it to obtain information on inhomogeneities in operation and degradation along the electrode surface via recording of current density distribution and localized impedance spectroscopy. Throughout the work, we will develop and use physical models that allow us to interpret the experimental findings and to gain additional insights.

 

What is your role in the cathode development?

The cathode plays a crucial role for the economic success of our battery. State-of-the-art electrodes show a limited round trip efficiency and durability, which limits the application of the system as a long-term storage technology. The development has therefore to start from the materials to the components and their integration into the full cell.

While IREC will focus on the development of the bi-functional catalyst and ADVENST will provide a strongly hydrophobic gas diffusion layer, these components have to be integrated into a suitable bi-functional electrode architecture, to unfold their full potential. At the DLR, we will identify suitable and stable materials that can withstand the harsh conditions during cycling and design an ideal pore system with adequate distribution of the gel-polymer-electrolyte which optimizes both reaction and transport of reactants and products. For that purpose, we have a range of different production methods at hand that can yield the desired properties, from which we will focus on solvent-free methods that are advantageous in terms of cost, scalability and environmental aspects. Ultimately, we need to find a compromise between the different requirements of oxygen evolution and oxygen reduction which are two and three-phase reactions, respectively, as well as between cost, stability and performance.

 

As Julian Seiler highlights, the German Aerospace Center´s expertise in operando characterization and cathode optimization is pivotal to the success of the HIPERZAB project. By leveraging cutting-edge technologies such as operando UV-Vis spectroscopy, FIB-SEM analysis, and their proprietary segmented cell technology, DLR is gaining unprecedented insights into the processes within zinc-air batteries. Combined with a strong focus on scalable and eco-friendly production methods, these efforts are laying the foundation for efficient, durable, and economically viable zinc-air battery systems. Through their collaborative approach with project partners such as IREC and ADVENST, DLR is advancing the boundaries of sustainable energy storage, ensuring that ERZAB technology is ready to meet the demands of a greener future.

 

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