Unravelling Hidden Parameters during Electrode Processing: The Role of Coherent Workflows in Electrocatalysis

Micron and nano-sized functional materials play a key role for future technologies that are currently developed in the field of energy conversion (electrolysers, fuel cells) and electrocatalysis. While new materials with outstanding properties are continuously developed, they rarely find their way into – urgently needed – large scale production and industrial applications [1]. One reason for this are hidden parameters that occur during ink formulation, coating (and decal transfer), cell assembly, and operation. We propose the development of coherent workflows that help us to identify reliable correlations. These should be developed for each electrocatalyst, bridging synthesis, electrode and gas diffusion electrode (GDE)/membrane electrode assembly (MEA) fabrication, and testing. All information, including “negative” results like crack formation, delamination, structural ageing and dissolution, must be reported until the relevant hidden parameters are deciphered, and the design chain is understood. Then, materials and electrodes derived from complementary processes and exhibiting subtle variations in composition and structure, can be evaluated against each other.<br/>However, this implies to fill the “blackbox” between technical catalysts and electrochemical testing in flow cells, GDEs or MEAs, with quantitative data on powders, ink formulations and coating properties. In the past years, we developed a toolbox of methods that starts from key control characteristics for technical catalysts, i.e., ball-milled pentlandites for hydrogenation reactions, that thereon enable the in situ analysis of ink formulations and pastes during the dispersion process and at application concentration [2,3]. This is followed by the assessment of the resulting coatings from large-area crack analysis down to the level of surface roughness and pore size characteristics [4]. Finally, this input is connected with performance and stability testing results to enable the comparison of different materials, the assessment of structure property relations, and ultimately to establish inline process control during electrode manufacturing. In this contribution, the developed methods will be summarized and related to their current limitations and prospects, in particular for unraveling hidden parameters during GDE assembly as well as in line process control.<br/><br/><b>References</b><br/>[1] Siegmund, Daniel; Metz, Sebastian; Peinecke, Volker; Warner, Terence E.; Cremers, Carsten; Grevé, Anna; Smolinka, Tom; Segets, Doris; Apfel, Ulf-Peter, JACS Au 1 (2021), 527 – 535.<br/>[2] Bapat, Shalmali; Segets, Doris, ACS Applied Nano Materials 3 (2020), 7384 – 739.<br/>[3] Bapat, Shalmali; Giehl, Christopher; Kohsakowski, Sebastian; Peinecke, Volker; Schäffler, Michael; Segets, Doris, Advanced Powder Technology 32 (2021), 3845 – 3859.<br/>[4] Jaster, Theresa; Albers, Simon; Leonhard, Armin; Kräenbring, Mena-Alexander; Lohmann, Heiko; Zeidler-Fandrich, Barbara; Özcan, Fatih; Segets, Doris; Apfel, Ulf-Peter, JPhys Energy 5 (2023), 024001.