Principals and strategies for constructing a highly reversible zinc metal anode in aqueous batteries

Among all the electrochemical energy storage systems, zinc-based batteries, such as zinc-air, zinc-metal, zinc-ion batteries, etc., have been recognized as an important group of candidates that could be potential alternatives to the currently dominant lead-acid and lithium-ion battery systems, because they have many unbeatable merits, including direct use of zinc metal as electrode; compatible with low cost, non-flammable, and environement-friendly aqueous electrolyte; assembly in ambient conditions; environmental benignity; and high safety. Currently, however, the capacitance, cycle life, and safety of zinc-based batteries were significantly degraded by zinc-water interaction problems that took place on the zinc metal electrode, including corrosion, passivation, shape change, and dendrite formation. This review gives a specific, comprehensive and in-depth summary of the mechanisms behind these problems; as well as state-of-the-art progress in the protection of the zinc electrode via intrinsic zinc alloy, zinc surface coating and electrolyte engineering in full pH range aqueous electrolyte. Future development trends, perspective and outlooks on the further blossom of these strategies are also presented.