TY - JOUR A1 - Schutjajew, K. A1 - Pampel, Jonas A1 - Zhang, W. A1 - Antonietti, M. A1 - Oschatz, M. T1 - Influence of pore architecture and chemical structure on the sodium storage in nitrogen‐doped hard carbons T2 - Small N2 - Hard carbon is the material of choice for sodium ion battery anodes. Capacities comparable to those of lithium/graphite can be reached, but the understanding of the underlying sodium storage mechanisms remains fragmentary. A two‐step process is commonly observed, where sodium first adsorbs to polar sites of the carbon (“sloping region”) and subsequently fills small voids in the material (“plateau region”). To study the impact of nitrogen functionalities and pore geometry on sodium storage, a systematic series of nitrogen‐doped hard carbons is synthesized. The nitrogen content is found to contribute to sloping capacity by binding sodium ions at edges and defects, whereas higher plateau capacities are found for materials with less nitrogen content and more extensive graphene layers, suggesting the formation of 2D sodium structures stabilized by graphene‐like pore walls. In fact, up to 84% of the plateau capacity is measured at potentials less than 0 V versus metallic Na, that is, quasimetallic sodium can be stabilized in such structure motifs. Finally, gas physisorption measurements are related to charge discharge data to identify the energy storage relevant pore architectures. Interestingly, these are pores inaccessible to probe gases and electrolytes, suggesting a new view on such “closed pores” required for efficient sodium storage. PB - Wiley Online Library KW - Sodium Ion Batteries KW - Hard Carbon KW - Storage Mechanism KW - Anode PY - 2021 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/52252 AN - OPUS4-52252 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-522529 VL - 17 IS - 48 SP - 2006767 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany