Scalable Production of Nickel-Cobalt Based Anode Materials for Alkaline Electrolysis: A Multi-Technique Approach from Micro Powder Analysis to Electrochemical Performance
Authors: Vinayakumar Vineetha , Jain Adarsh , Chatwani Mohit , Wagner Timo , Marcks Christian , Wöhrl Nicolas , Mechler Anna K. , Segets Doris 
Published: February 2024

The growing concern about environmental degradation caused by the use of conventional fossil fuels has triggered a significant paradigm shift in the research and development of sustainable energy sources such as hydrogen. Water electrolysis is a promising approach for achieving efficient energy conversion and storage [1]. While this process has made significant advancements recently, an in-depth understanding of the entire process chain from commercial powder materials to electrodes and their electrocatalytic activity with useful correlations between involved steps are still underexplored.

Here our research aims toward a thorough and continuous evaluation of Ni-Co-O-based electrocatalysts to parameterize the process chain to unravel interdependencies and understand the correlation between the material, manufacturing process, electrode structure and final cell performance. The applied methodology incorporates various complementary techniques to analyze the physical and chemical properties of the materials involved consistently throughout the entire process chain. After preliminary characterization of commercial Ni-Co-O micropowder using transmission electron microscopy and energy-dispersive X-ray spectroscopy, ink formulations, obtained from the powder, were optimized using analytical centrifugation [2] and Hansen parameter calculations [3]. Then selected inks were transferred to electrodes by coating these inks on Ni plates via ultrasonic spray deposition. Effect of post-treatments such as vacuum annealing and surface plasma treatment on the electrode stability against delamination was also investigated. To quantify micro features of large electrode areas and analyze their surface characteristics, we developed a framework by employing atomic force microscopy. So evaluated electrodes were finally tested for their functionality as anodes for alkaline water electrolysis where useful correlations were established between the properties of the catalyst ink/ coated electrodes and their electrochemical activity/ stability. In agreement to the identified structural features, our preliminary results indicate that plasma treated Ni-Co-O electrodes show lower overpotentials and higher stabilities in comparison with the pristine and vacuum annealed electrodes due to increased adhesion and surface properties (roughness etc.) induced by plasma.

This study highlights the need for careful evaluation of the entire process chain at various stages with knowledge feedback from previous steps for continuous electrode improvisation. Optimization of each individual step is crucial to enhance the final performance of the catalyst. In our future attempts, we plan to scale-up our approach to larger electrode areas (up to 100x100 cm2) where a systematical analysis and optimization of all involved steps can be easily adapted closer to industrial settings.

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Bapat, S., et al., On the state and stability of fuel cell catalyst inks. Advanced Powder Technology, 2021. 32(10): p. 3845-3859.

Anwar, O., et al., Hansen parameter evaluation for the characterization of titania photocatalysts using particle size distributions and combinatorics. Nanoscale, 2022. 14(37): p. 13593-13607.

Figure 1