A weakly solvating electrolyte towards practical rechargeable aqueous zinc-ion batteries.

Structure deterioration and side reaction, which originated from the solvated H2O, are the main constraints for the practical deployment of both cathode and anode in aqueous Zn-ion batteries. Here we formulate a weakly solvating electrolyte to reduce the solvating power of H2O and strengthen the coordination competitiveness of SO42- to Zn2+ over H2O. Experiment results and theoretical simulations demonstrate that the water-poor solvation structure of Zn2+ is achieved, which can (i) substantially eliminate solvated-H2O-mediated undesirable side reactions on the Zn anode. (ii) boost the desolvation kinetics of Zn2+ and suppress Zn dendrite growth as well as structure aberration of the cathode. Remarkably, the synergy of these two factors enables long-life full cells including Zn/NaV3O8·1.5H2O, Zn/MnO2 and Zn/CoFe(CN)6 cells. More importantly, practical rechargeable AA-type Zn/NVO cells are assembled, which present a capacity of 101.7 mAh and stability of 96.1% capacity retention after 30 cycles at 0.66 C.

Highly Reversible Tin Film Anode Guided via Interfacial Coordination Effect for High Energy Aqueous Acidic Batteries.

Sn metal is a preferable choice as anode material for aqueous acidic batteries due to its acid-tolerance, non-toxicity, and ease of recycling. However, the large size and irregular deposition morphology of polyhedral Sn particles are bad for constructing stable and high-capacity Sn metal anode because of severe hydrogen evolution and metal shedding. To tackle this critical issue, 4-tert-octylphenol pentaethoxylate (POPE) is used as an electrolyte additive to generate a thin-film Sn anode with reversible stripping/plating behavior. POPE can not only induce homogeneous surface chemistry by adsorbing on the Sn surface via coordination bonds but also inhibit hydrogen evolution by modulating the solvation shell of Sn2+. The Sn film anode delivers improved electrochemical stability over 480 h with satisfactory rate performance and low polarization. Moreover, the as-assembled PbO2//Sn battery can also provide outstanding durability at 10 mAh cm-2. This work offers new inspiration for developing a reversible Sn metal film anode.