Hydrogen-bond-mediated interfacial chemistry enables reversible anodes for durable Sn–air batteries

Tin (Sn)–air batteries promise high capacity and environmentally benign chemistry, but their progress is fundamentally constrained by the poor reversibility of Sn anodes. The key intermediate Sn(OH) 3 − is electrostatically excluded from the Helmholtz layer, resulting in poor stripping/plating reversibility. Herein, we propose a urea-enabled interfacial regulation strategy to improve the reversibility of Sn anodes in which urea stabilizes the interfacial adsorption of the intermediate via hydrogen-bond binding to Sn(OH) 3 − and van der Waals coupling with carbon substrates. Molecular dynamics (MD) simulations revealed that the strong (urea)N-H···O(Sn(OH) 3 − ) hydrogen bonding regulated the local solvation environment and reduced the desolvation free energy. In parallel, urea reorganized the electrical double layer (EDL) to form a more hydrophobic interfacial microenvironment, which suppressed hydrogen evolution. This achieved highly reversible Sn deposition/stripping, allowing symmetric cells to operate stably for >1000 h at 5 mA cm −2 and full cells to deliver 381.2 mWh g −1 with a cycling life of 769 h. This work establishes a hydrogen bond regulation strategy for Sn–air batteries to regulate the interfacial chemistry of anodes. Urea interacts with Sn(OH) 3 − through N–H···O hydrogen bonds, which facilitates its interfacial adsorption and desolvation. At the same time, urea helps reconstruct a more hydrophobic electric double-layer environment and suppresses the hydrogen evolution side reaction. These effects together lead to more reversible Sn deposition/stripping and improved cycling performance of the Sn–air battery. Download: Download high-res image (115KB) Download: Download full-size image