Electrochemo-Mechanics insights of Sn foil anode in Sodium-Ion batteries.

The development of high-performance sodium-ion batteries (SIBs) is crucial to meeting the growing demand for low-cost, sustainable energy storage alternatives to lithium-ion batteries (LIBs). However, achieving stable cycling performance in SIBs is challenging, particularly with tin (Sn) foil anodes, which suffer from issues like sodium trapping and structural degradation due to significant volume changes during sodiation and desodiation. In this study, we investigate the electrochemo-mechanical behavior of Sn foil anodes, focusing on the mechanisms of sodium trapping and structural evolution that impair battery performance. We demonstrate that sodiation forms a porous coral-like structure in Sn, which, while increasing surface area, also contributes to severe volume expansion, crack formation, and diffusive sodium trapping. We further explore zinc (Zn)-doped Sn foils, revealing that Zn-rich phases create additional fast sodium diffusion channels, significantly reducing sodium retention and enhancing the anode's structural integrity. Based on these insights, we propose several improvement strategies, including electrolyte additives, optimized electrode architecture, microstructural defect engineering, and artificial solid-electrolyte interface (SEI) coatings, all aimed at enhancing cycle stability and performance. This work provides a comprehensive understanding of Sn-based anodes and offers practical pathways for advancing SIBs technology.