High-Energy Sn-Ni and Sn-Air Aqueous Batteries via Stannite-Ion Electrochemistry

Tin is promising for aqueous batteries (ABs) due to its multiple electrons' reactions, high corrosion resistance, large hydrogen overpotential, and excellent environmental compatibility. However, restricted to the high thermodynamic barrier and the poor electrochemical kinetics, efficient alkaline Sn plating/stripping at facile conditions has not yet been realized. Here, for the first time, we demonstrate a highly reversible stannite-ion electrochemistry and construct a novel paradigm of high-energy Sn-based ABs. Combined spectroscopic characterization, electrochemical evaluation, and theoretical computation reveal the thermodynamic merits with a low reaction energy barrier and feasible H2O participation in Sn-ion reduction as well as the kinetic merits with fastened surface charge transfer and SnO22- diffusion. The resultant alkaline Sn anode delivers a low potential of -1.07 V vs Hg/HgO, a specific capacity of 450 mA h g-1, a Coulombic efficiency of near 100%, superb rate capability at 45.5 A g-1, and excellent cycling durability without dendrite and dead Sn. As a proof of concept, we developed new high-energy Sn-based ABs, including 1.45 V Sn- Ni with 314 W h kg-1 (58 kW kg-1 and over 15,000 cycles) and 1.0 V Sn-air with 420 W h kg-1 (lifespan over 1900 h), on the basis of masses from cathode and anode active materials. The findings prove the feasibility of the alkaline Sn metal anode, and the new suite of high-energy Sn-based ABs may be of immediate benefit toward safe, reliable, and affordable energy storage.

Automated summary

Tin shows promising potential for aqueous batteries due to its multiple electron reactions, high corrosion resistance, large hydrogen overpotential, and excellent environmental compatibility. However, the efficient alkaline tin plating/stripping process has not been achieved due to high thermodynamic barrier and poor electrochemical kinetics. In this study, a highly reversible stannite-ion electrochemistry was demonstrated for the first time, leading to the development of a novel paradigm of high-energy Sn-based aqueous batteries. The alkaline tin anode exhibited low potential, high specific capacity, superb rate capability, and excellent cycling durability, which proves the feasibility of the alkaline Sn metal anode and suggests the potential of high-energy Sn-based aqueous batteries for safe, reliable, and affordable energy storage.