Exploring Sodium Ion Storage: Combining a MOF Derived Carbon Core with a Sieving Carbon Shell to Illuminate Adsorptive Site Influences
- Unlike lithium-ion batteries (LIBs) where crystalline graphite is commonly used as the negative electrode material, disordered carbons are regarded as more promising forsodium-ion batteries (SIBs). However, further advances towards better reversibility and higher specific capacity are still needed to match or even exceed the properties of graphite in LIBs. The main challenge is the complex and unpredictable Na+ storage mechanism in disordered carbons. [1] Method: Recently, Matsukawa et al. have reported that the reversibility of (de)sodiation processes of disordered carbons is better for ultra microporous carbons.[2] Ultra micropores are accessible only to Na+ ions and not to solvent molecules. Therefore, the ultra micopores can be used for Na-storage, however, do not significantly contribute to side reactions caused by solid-electrolyte interphase (SEI) formation, which reduces the related irreversible capacity loss. Building on this concept, the origins of specific capacity andUnlike lithium-ion batteries (LIBs) where crystalline graphite is commonly used as the negative electrode material, disordered carbons are regarded as more promising forsodium-ion batteries (SIBs). However, further advances towards better reversibility and higher specific capacity are still needed to match or even exceed the properties of graphite in LIBs. The main challenge is the complex and unpredictable Na+ storage mechanism in disordered carbons. [1] Method: Recently, Matsukawa et al. have reported that the reversibility of (de)sodiation processes of disordered carbons is better for ultra microporous carbons.[2] Ultra micropores are accessible only to Na+ ions and not to solvent molecules. Therefore, the ultra micopores can be used for Na-storage, however, do not significantly contribute to side reactions caused by solid-electrolyte interphase (SEI) formation, which reduces the related irreversible capacity loss. Building on this concept, the origins of specific capacity and irreversible losses were further explored by modifying the chemical composition of zeolitic imidazolate framework (ZIF-8) derived carbons, while maintaining comparable porosity. This involved adjusting the nitrogen content through temperature variation. Additionally, these ZIF-8 derived carbons were enhanced with a protective ion sieving carbon shell formed by chemical vapor deposition. This shell enables effective distinction between reversible and irreversible Na+ storage. Results: The tailor-made core-shell carbons with higher nitrogen content demonstrate greater capacity in the sloping region, but lower capacity in the plateau region of the voltage profile. In addition, they show reduced specific capacities compared to materials with lower nitrogen content. Lastly, it is important to highlight that the incorporation of sieving carbons results in a significant overall increase in capacity compared to materials without sieving carbons. The highest capacities were obtained for the core shell carbon pyrolyzed at 1000°C reaching reversible capacities of 381 +/- 4 mAh g–1 . Discussion: The nitrogen active sites in the as-synthesized materials facilitate the adsorption of Na+ ions, indicating that Na+ ions preferentially adhere to these active sites during the sodiation process. Moreover, the relatively low capacity observed in materials with higher nitrogen content may be attributed to their lower electrical conductivity.…


| Autor*innen: | Shu-Han WuORCiD |
|---|---|
| Koautor*innen: | Paul Alexander AppelORCiD, J. Geisler, A. Freytag, Simon Dietzmann, Jian Liang LowORCiD, Jonas Krug von NiddaORCiD, P. Adelhelm, Tim-Patrick FellingerORCiD |
| Dokumenttyp: | Posterpräsentation |
| Veröffentlichungsform: | Präsentation |
| Sprache: | Englisch |
| Jahr der Erstveröffentlichung: | 2025 |
| Organisationseinheit der BAM: | 3 Gefahrgutumschließungen; Energiespeicher |
| 3 Gefahrgutumschließungen; Energiespeicher / 3.6 Elektrochemische Energiematerialien | |
| DDC-Klassifikation: | Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Angewandte Physik |
| Freie Schlagwörter: | Core-shell materials; Hard carbon; Sodium-ion batteries |
| Themenfelder/Aktivitätsfelder der BAM: | Energie |
| Energie / Elektrische Energiespeicher und -umwandlung | |
| Veranstaltung: | Batterieforum 2025 |
| Veranstaltungsort: | Berlin, Germany |
| Beginndatum der Veranstaltung: | 21.01.2025 |
| Enddatum der Veranstaltung: | 23.01.2025 |
| Verfügbarkeit des Dokuments: | Datei im Netzwerk der BAM verfügbar ("Closed Access") |
| Datum der Freischaltung: | 15.12.2025 |
| Referierte Publikation: | Nein |

