Highly rechargeable aqueous Sn-metal-based hybrid-ion batteries

Tin (Sn) metal, with its intrinsic resistance to the hydrogen evolution reaction (HER), holds great promise as an anode for safe and rechargeable aqueous Sn-metal batteries (ASBs). However, the major challenges for their practical deployment include uneven Sn deposition and low Sn²⁺/Sn⁴⁺ reaction reversibility. To mitigate these challenges, we design ASBs from both anode and electrolyte. First, a stannophilic silver-coated vertical graphene (Ag-VG) host improves the nucleation kinetics and uniform Sn deposition. Second, a biphasic H₂O/ionic liquid (IL) electrolyte confines Sn²⁺ within the aqueous phase, suppressing the formation of Sn⁴⁺ at the cathode side and eliminating the usage of an ion exchange membrane. The biphasic electrolyte and Ag-VG host are coupled with various types of cathodes (herein, halogens, LiCoO₂, and Li₂MnO₄) to fabricate full ASBs. Improved cycling stability and Coulombic efficiency are clearly observed. This work highlights a facile strategy for advancing ASBs.