Polymer-derived silicon carbonitride ceramic (SiCN) is used as an electrode material to prepare cylindrical sodium/sodium ion cells for solid-state NMR investigations. During galvanostatic cycling structural changes of the environment of sodium/ sodium ions are investigated by applying 23 Na in-situ solid-state NMR. Changes of the signals assigned to sodium metal, intercalated sodium cation and sodium cation originating from the electrolyte are monitored as well as the occurrence of an additional signal in the region of metallic sodium. The intensity of this additional signal changes periodically with the cycling process indicating the reversibility of structures formed and deformed during the galvanostatic cycling. To identify interactions of sodium/sodium ions with the SiCN electrode materials, the cycled SiCN material is studied by 23 Na ex-situ MAS NMR at high spinning rates of 20 and 50 kHz to obtain appropriate spectral resolution.

Polymer‐derived silicon oxycarbide ceramics (SiCO) have been considered as potential anode materials for lithium‐ and sodium‐ion batteries. To understand their electrochemical storage behavior, detailed insights into structural sites present in SiCO are required. In this work, the study of local structures in SiCO ceramics containing different amounts of carbon is presented. 13C and 29Si solid‐state MAS NMR spectroscopy combined with DFT calculations, atomistic modeling, and EPR investigations, suggest significant changes in the local structures of SiCO ceramics even by small changes in the material composition. The provided findings on SiCO structures will contribute to the research field of polymer‐derived ceramics, especially to understand electrochemical storage processes of alkali metal/ions such as Na/Na+ inside such networks in the future.