Solvent-Driven Na\nStorage in SnS<sub>2</sub> Anodes:\nAtomistic Simulation-Guided Strategies for Reversible Reactions, Solid\nElectrolyte Interphase, and Morphological Transformation

Crystalline\nSnS<sub>2</sub> accommodates Na ions through\nintercalation–conversion–alloying\n(ICA) reactions, exhibiting a natural potential for high energy storage,\nwhile its layered structure facilitates rapid charging. However, these\nintrinsic advantages are not fully realized in practical battery applications.\nHerein, utilizing an innovative integration of machine-learning-based\nthermodynamics, artificial-neural-network-assisted molecular dynamics,\nand density functional theory, specific solvents are demonstrated\nto effectively tailor the reaction pathways. This strategy not only\nsteers phase transition pathways but also significantly reduces the\nformation of the solid electrolyte interphase (SEI), which is a common\nissue in recent battery research. These characteristics of solvents\nenable reversible ICA reactions and also aid the transformation of\nmicrosized SnS<sub>2</sub> particles into 3D porous nanostructures\nwith minimal SEI formation. The performance of our Na–SnS<sub>2</sub> half-cells achieve 1100 mAh g<sup>–1</sup> (97% of\nthe theoretical capacity) at 0.5 C, placing them among the top performers\nfor Na storage. By moving beyond the traditional view of electrolyte\nsolvents as a simple medium for ion transport, this work highlights\nthe critical impact of solvent selection on enabling reversible reactions\nand morphological transformation of SnS<sub>2</sub> anodes with minimal\nSEI formation and setting benchmarks for anode performance in energy\nstorage systems based on ICA reactions.