Morphology-Diversified Sn Growth for Aqueous Acidic Batteries

Aqueous acidic batteries utilizing corrosion-resistant Sn metal anodes have emerged as promising candidates for safe energy storage systems. However, uncontrolled dendritic growth under high-rate operation remains a major obstacle. Here we showed that artificial layers acting solely as a physical barrier are insufficient to regulate Sn deposition. We instead introduced an active-site-rich porous carbon (PC) layer with abundant N-defect sites that simultaneously governs the interfacial charge distribution and Sn nucleation. This architecture enabled highly uniform Sn deposition both within the PC layer and on the underlying substrate. Crucially, we identified the formation of an H3O+-enriched electric double layer in acidic electrolytes as the key factor driving Sn nanoparticle deposition within the carbon layer. Consequently, this artificial layer strategy significantly improved the reversibility and stability of Sn anodes, achieving a high average Coulombic efficiency of 99.72% for 16,000 cycles in asymmetric cells and maintaining 83.5% capacity retention after 20,000 cycles in pouch cells.