Synthesis of Ni-based catalyst materials for AEM electrolysers Noah Bryan , Mark Copley, Ivana Hasa Warwick Manufacturing Group, University of Warwick, UK The global drive towards sustainable energy generation and storage has prompted increasing academic and commercial interest in electrochemical systems, such as batteries and electrolysers/ fuel cells. These systems are intrinsically complex in their manufacturing and operation due to the high degree of co-dependence of variables from molecular to macroscopic scales [1]. Importantly, their overall performance strongly relies on the properties of the active materials used to store or convert energy. Traditional fuel cell and electrolyser systems have utilised platinum group metals (PGMs) to boast long-term stability and high catalytic activity. Despite this, as the demand for hydrogen and the cost of PGMs continue to rise, the search for alternative catalyst materials is necessary. Nickel is considered a viable alternative for certain electrolyser applications due to its chemical likeliness to platinum, however, significant challenges are yet to be overcome in its synthesis at a large scale. Nickel-based oxides have already proved useful in commercial Li-ion batteries as the standard cathode material – NMC, LiNi x Mn y Co z O 2 (x+y+z=1) – and researchers have indicated promising performance in electrolyser/fuel cells at smaller scales [2]. Current industrial synthesis methods utilise solid-state or ‘batch’ co-precipitation reactions in a continuously stirred tank reactor (CSTR) but suffer from limitations, including long reaction times, inhomogeneous mixing, and challenges controlling the particle’s size, morphology and elemental distribution [3]. The Laminar Couette- Taylor Reactor (LCTR) reactor enables a continuous co-precipitation reaction that achieves high-purity, spherical particles faster than industrial methods while capable of intricate particle designs, including core-shell and concentration-gradient particles [4]. Promising results have been reported at the lab-scale level, however, the use of LCTR for industrially relevant scale is still limited, therefore further research is needed to demonstrate the method’s feasibility at scale [5]. The LCTR series ranges from research (>20mL) to commercial (<1000L) applications, thus offering a viable solution to bridge the gap between academia and industry. Building on previous reports on various Ni-based materials, this work focuses first on adapting and optimising the synthesis of such Ni-based catalysts, formerly explored using lab-scale industrial synthesis methods, before developing a procedure to implement best practices to the LCTR and testing in operating electrolysers. Acknowledgements: EPSCR is acknowledged for funding the EngD studentship as well as Johnson Matthey for providing an industrial sponsorship.
Figure 1. Graphical Abstract of my EngD project. The top left illustration of the electrolyser system is sourced from Chen et al. [6]. The top right XRD spectra show the effect of calcination temperature and time transforming the precursor into the desired spinel phase. The bottom bar shows a synthesis overview: process parameters and characterisation techniques used within the project.
References 1. Malik et al., Materials Today Energy , 2022, 28 2. Jiang et al., Advanced Functional Materials , 2022, 32 3. Schmuch et al., Material Matters , 2020, 15 (2) 4. Kim and Kim, Crystal Growth and Design , 2017, 17 , p3677-3686 5. Zhang et al., Nature , 2022, 610 (67-73) 6. Chen et al., Energy & Environmental Science 2021 , 2021, 14 (6338)
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