Activating Progressive Sn²⁺ Nucleation by Micellar Structure Electrolyte for Dead-Sn-Free Aqueous Batteries

The instantaneous nucleation of Sn originating from the uncontrolled diffusion of Sn²⁺ ions typically forms large, electrochemically inactive "dead Sn" that severely constraints the plating/stripping reversibility of Sn anode for acidic aqueous batteries. Herein, nanoscale spatial confinement of Sn²⁺ ions is realized in SnSO₄ electrolyte by strategically dictating spontaneous assembly of nanomicelles with amphipathic sulfolane. The as-constructed locally heterogeneous environment ensures the sustainable release of Sn²⁺ ions, which reprograms the nucleation manner from instantaneous to progressive modes. The consequent progressive formation of Sn nuclei triggers size refinement of electrodeposited Sn, thereby alleviating the "dead Sn" issue. Meanwhile, the reaction competitivity of Sn²⁺ reduction over hydrogen evolution side reaction is effectively strengthened as the consecutive hydrogen bonding network among bulk water is disrupted by the micellar structure. Consequently, Sn anode exerts an unprecedently high average Coulombic efficiency of 99.97% and witnesses a prominent life span extension from 710 to 8400 h (~ 11-fold enhancement). In a dual-plating configuration, the Sn||Mn full battery delivers a 1.6 V discharge plateau and sustains 790 cycles, demonstrating practical feasibility. Our findings underscore the decisive role of the very initial nucleation behavior in regulating metal electrochemistry, applicable to other multivalent anodes.