A Key to Material's Stability: Tuning Pyrolysis Temperature in SnSx@C Anodes for Sodium-Ion Batteries

• Published in: Small (Weinheim an der Bergstrasse, Germany) p. e04485
• Main Authors: Zarach, Zuzanna, Sawczak, Mirosław, Dosche, Carsten, Trzciński, Konrad, Szkoda, Mariusz, Graczyk-Zając, Magdalena, Riedel, Ralf, Wittstock, Gunther, Nowak, Andrzej P
• Format: Journal Article
• Language: English
• Published: 31.07.2025
• ISSN: 1613-6829; 1613-6829
• DOI: 10.1002/smll.202504485

Developing robust and efficient anodes is essential for advancing sodium-ion battery technology. Herein, a systematic investigation of SnSx@C composites prepared at different pyrolysis temperatures to elucidate how their structural, surface, and electrochemical properties govern sodium-ion storage is reported. The study reveals that a lower synthesis temperature traps extra sulfur within the carbon matrix, which hampers the complete SnS conversion reaction and Na+ intercalation processes. In contrast, pyrolysis at 800 °C facilitates more thorough sulfur release, yielding a defect-rich but stable carbon matrix that supports enhanced sodiation/desodiation reversibility. Operando Raman spectroscopy and X-ray photoelectron spectroscopy depth profiling confirm that the pyrolysis temperature strongly affects the formation and stability of the solid electrolyte interphase. The SnSx@C material pyrolyzed at 800 °C not only possesses superior ion transport characteristics but also delivers enhanced electrochemical performance, maintaining a stable capacity of ≈500 mAh g-1 at C/10 and retaining a substantial fraction of its capacity over 100 cycles, in contrast to the rapidly decaying capacity of the material pyrolyzed at 600 °C.Developing robust and efficient anodes is essential for advancing sodium-ion battery technology. Herein, a systematic investigation of SnSx@C composites prepared at different pyrolysis temperatures to elucidate how their structural, surface, and electrochemical properties govern sodium-ion storage is reported. The study reveals that a lower synthesis temperature traps extra sulfur within the carbon matrix, which hampers the complete SnS conversion reaction and Na+ intercalation processes. In contrast, pyrolysis at 800 °C facilitates more thorough sulfur release, yielding a defect-rich but stable carbon matrix that supports enhanced sodiation/desodiation reversibility. Operando Raman spectroscopy and X-ray photoelectron spectroscopy depth profiling confirm that the pyrolysis temperature strongly affects the formation and stability of the solid electrolyte interphase. The SnSx@C material pyrolyzed at 800 °C not only possesses superior ion transport characteristics but also delivers enhanced electrochemical performance, maintaining a stable capacity of ≈500 mAh g-1 at C/10 and retaining a substantial fraction of its capacity over 100 cycles, in contrast to the rapidly decaying capacity of the material pyrolyzed at 600 °C.