O3-type layered oxides are promising cathode materials for sodium-ion batteries because of their low cost and high energy density. Nevertheless, beside the capacity degradation during extended cycling, the processability at atmosphere remains a major challenge. In this study, different particle coating strategies are presented to mitigate these issues. In addition, the coating strategies are demonstrated at both laboratory scale and kilogram-scale pilot production, highlighting their scalability.
Through particle coating screenings on NFM111 as a model type material, a variety of different coatings like boric acid, aluminum oxide, magnesium hydroxide and their effects on the electrochemistry in sodium coin cells were studied. In addition, the processability of the coated cathode active materials under humid conditions was examined using thermogravimetric analysis.
The scale-up was accomplished using high-shear mixers at pilot scale, followed by subsequent oven sintering. The potential impact of high sintering temperatures on the crystal structure was monitored using X-ray diffraction measurements. The detailed characterization of the particle coatings and their influence on particle morphology was carried out using scanning electron microscopy (SEM).
The resulting scalable materials exhibited enhanced humidity resistance for typical pilot line time spans and a reduced amount of alkaline surface species, resulting in an improvement of up to 30% in cyclic stability after 50 cycles in the electrochemical analytics.
In summary, the results highlight that particle coating strategies not only improve humidity tolerance but also significantly boost the cyclic stability of O3-type layered oxide cathodes, offering a scalable route to pilot-line production of cathode materials in sodium-ion batteries.

ACKNOWLEDMENT:
This work was supported by the German Federal Ministry of Education and Research (BMBF) in the project SIB:DE (03XP0627E).

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