In Situ Constructing Solid Electrolyte Interphase and Optimizing Solvation Shell for a Stable Zn Anode

The development of aqueous zinc ion batteries is restricted by the unstable Zn metal anode, which comes from the dendrite and hydrogen evolution reaction on the Zn electrode-electrolyte interface. Here, melamine additive is introduced into the electrolyte to build a stable Zn anode. The melamine additive supplies two functions: one is optimizing the Zn2+ solvation structure to produce [Zn(H2O)m(melamine)n]2+; the other is in situ constructing a C,N-solid electrolyte interphase layer. The bifunction of the additive reduces the hydrogen evolution reaction, induces a uniform Zn deposition without dendrite, and protects Zn from electrolyte corrosion. As a result, the Zn anode in ZnSO4 + melamine shows a lower overpotential, higher coulombic efficiency, and longer cycle life, in contrast with the pure ZnSO4 electrolyte, thus proving that this bifunctional additive is an effective method to achieve a stable Zn anode.