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Alloying‐type antimony (Sb) with high theoretical capacity is a promising anode candidate for both lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs). Given the larger radius of Na+ (1.02 Å) than Li+ (0.76 Å), it was generally believed that the Sb anode would experience even worse capacity degradation in SIBs due to more substantial volumetric variations during cycling when compared to LIBs. However, the Sb anode in SIBs unexpectedly exhibited both better electrochemical and structural stability than in LIBs, and the mechanistic reasons that underlie this performance discrepancy remain undiscovered. Here, using substantial in situ transmission electron microscopy, X‐ray diffraction, and Raman techniques complemented by theoretical simulations, we explicitly reveal that compared to the lithiation/delithiation process, sodiation/desodiation process of Sb anode displays a previously unexplored two‐stage alloying/dealloying mechanism with polycrystalline and amorphous phases as the intermediates featuring improved resilience to mechanical damage, contributing to superior cycling stability in SIBs. Additionally, the better mechanical properties and weaker atomic interaction of Na−Sb alloys than Li−Sb alloys favor enabling mitigated mechanical stress, accounting for enhanced structural stability as unveiled by theoretical simulations. Our finding delineates the mechanistic origins of enhanced cycling stability of Sb anode in SIBs with potential implications for other large‐volume‐change electrode materials. [ABSTRACT FROM AUTHOR]

Rechargeable batteries that make renewable energy resources feasible for electrification technologies have been extensively investigated. Their corresponding performance is strongly dependent on the structural characteristics and chemical dynamics of internal electrode and electrolyte materials under operating conditions. To enhance battery performance and lifetime, a comprehensive understanding of the structure‐dynamics‐performance correlation of such materials under different working conditions is of great significance. Fortunately, in situ transmission electron microscopy (TEM) encompassing high‐resolution imaging, diffraction, and spectroscopic analysis, offers unprecedented insights into the nano/atomic scale structural changes and degradation pathways of rechargeable battery materials under operational conditions. Such insights are pivotal for a deep‐rooted understanding of reaction mechanisms and the structure‐activity interplay within battery materials. This work, therefore, highlights the advances in in situ TEM's utility in unveiling dynamic chemical and physical changes in real‐time within battery materials of rechargeable batteries. Electrochemical processes and degradation mechanisms are systematically explored and summarized. Moreover, the technical progress, challenges, and valuable insights provided by in situ TEM techniques for addressing critical issues in battery materials are underscored. The work concludes with a discussion of emerging research directions that hold the potential to revolutionize the renewable energy field in the near future. [ABSTRACT FROM AUTHOR]

Alloying-type antimony (Sb) with high theoretical capacity is a promising anode candidate for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Given the larger radius of Na + (1.02 Å) than Li + (0.76 Å), it was generally believed that the Sb anode would experience even worse capacity degradation in SIBs due to more substantial volumetric variations during cycling when compared to LIBs. However, the Sb anode in SIBs unexpectedly exhibited both better electrochemical and structural stability than in LIBs, and the mechanistic reasons that underlie this performance discrepancy remain undiscovered. Here, using substantial in situ transmission electron microscopy, X-ray diffraction, and Raman techniques complemented by theoretical simulations, we explicitly reveal that compared to the lithiation/delithiation process, sodiation/desodiation process of Sb anode displays a previously unexplored two-stage alloying/dealloying mechanism with polycrystalline and amorphous phases as the intermediates featuring improved resilience to mechanical damage, contributing to superior cycling stability in SIBs. Additionally, the better mechanical properties and weaker atomic interaction of Na-Sb alloys than Li-Sb alloys favor enabling mitigated mechanical stress, accounting for enhanced structural stability as unveiled by theoretical simulations. Our finding delineates the mechanistic origins of enhanced cycling stability of Sb anode in SIBs with potential implications for other large-volume-change electrode materials., (© 2024 Wiley-VCH GmbH.)